US20120296543A1 - Automatic work brake - Google Patents

Abstract

A vehicle, air brake system is presented with an improved service work brake arrangement. The arrangement may provide a service work brake function or both a service work brake function and a parking brake function for the vehicle. The arrangement may provide an improved service work brake arrangement disposed within a housing for reducing the number of components and plumbing required to achieve this functionality versus prior known systems. The arrangement may utilizes a pneumatic latching valve to deliver pressurized air for applying a vehicle's service brakes. The pneumatic latching valve opens upon receiving a pneumatic control signal from an electronically controlled valve and closes upon receiving a pneumatic control signal from another source. In addition, a controller and control logic may be provided for controlling the arrangement.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application is a continuation of prior U.S. application Ser. No. 12/709,891, filed Feb. 22, 2010, which is a divisional of prior U.S. application Ser. No. 11/433,249, filed May 12, 2006, now U.S. Pat. No. 7,690,735, the entire contents of each of which is herein fully incorporated by reference.
BACKGROUND OF THE INVENTION
• Commercial vehicles, such as for example tractor trailers, often utilize air brake systems. A typical air brake system is capable of performing a service brake function and a park brake function. Service braking or normal braking refers to actuating the vehicle's brakes by depressing a brake pedal to deliver compressed air to a brake actuator. Service braking is used to slow the vehicle or bring the vehicle to a stop. Once stopped, the driver may wish to apply the park brakes to prevent the vehicle from rolling. Typical vehicle air brake systems utilize spring brakes to perform the park brake function. Spring brakes, as are known in the art, utilize spring force to engage the brakes and hold the vehicle stationary. Air pressure is used to disengage the brakes by compressing the spring in order to allow the vehicle to move.
• Some vehicle air brake systems also include a work brake function for commercial vehicles that stop and start frequently, such as for example waste collection vehicles. Work braking refers to using a service brake application to perform a temporary park brake function. In other words, utilizing compressed air to apply the service brakes to keep the vehicle from roiling while the vehicle is parked. Utilizing service brakes in applications with frequent stopping and starting is preferable to utilizing park brakes because the service brakes are more durable and use less compressed air.
• Typical work brake systems, however, are either not fail safe or have complicated fail safe systems. A fail safe work brake system will apply the park brakes if a particular vehicle condition exists or a contemplated specific system failure occurs, such as loss of compressed air. An example of a complex fail sale work brake system can be found in U.S. Pat. No. 5,458,402.
• Furthermore, electro-pneumatic brake systems for commercial vehicles have been developed, though presently are not widely used. Present work brake systems, including known systems with complex pneumatic fail safe systems, have no provisions for providing fail safe operation in case of an electrical failure or driver error (e.g. the driver turns the ignition off while the work brake is engaged).
SUMMARY
• The present invention relates generally to vehicle air brake systems. In particular the present invention relates to a vehicle air brake system with an improved service work brake arrangement. The arrangement improves the work brake system for either a pneumatic failure or an electrical failure. Thus, the logic of the system and method of the present invention may include both electrical and pneumatic components. The arrangement may provide a service work brake function or both a service work brake function and a parking brake function for the vehicle. The arrangement may provide an improved service work brake arrangement disposed within a housing for reducing the number of components and plumbing required to achieve this functionality versus prior known systems.
• Furthermore, the invention may include a controller and control logic for controlling the arrangement. The controller and control logic may control the work brake and park brake functions, as well as other vehicle functions, based on data received from a variety of input sources. Thus, the controller may enable or disable certain vehicle functions as a function of the data received or inferences made from the data.
• In one embodiment, the arrangement utilizes a pneumatic latching valve to deliver pressurized air for applying a vehicle's service brakes. The pneumatic latching valve opens upon receiving a pneumatic control signal from an electronically controlled valve and closes upon receiving a pneumatic control signal from another source or via spring return in absence of supply pressure. In another embodiment, an electronic control unit is employed to automatically engage and disengage the work brake function based on receiving input indicative of one or more of: the status of the vehicle, the status of the driver, the intent of the driver, and the plausibility of the driver's intent.
BRIEF DESCRIPTION OF THE DRAWINGS
• The foregoing features of aspects of the present invention will become apparent to one skilled in the art to which the present invention relates upon consideration of the following description of the invention with reference to the accompanying drawings, in which:
• FIG. 1 is a partial schematic representation of a prior art air brake system for a vehicle;
• FIG. 2 is a partial schematic representation of an exemplary embodiment of an air brake system for a vehicle according to the principles of present invention.
• FIG. 3 is a schematic representation clan exemplary embodiment of a valve arrangement of the system ofFIG. 2;
• FIG. 4 is a schematic representation of a valve arrangement of a second exemplary embodiment of the air brake system according to the principles of present invention;
• FIG. 5 is a schematic representation of a valve arrangement of a third exemplary embodiment of the airbrake system according to the principles of present invention;
• FIG. 6 is schematic representation of an exemplary embodiment of a controller for the system ofFIG. 2; and
• FIG. 7 is a flow chart of an exemplary embodiment of control logic for the controller ofFIG. 6.
DETAILED DESCRIPTION
• While various aspects and concepts of the invention are described and illustrated herein as embodied in combination in the exemplary embodiments, these various aspects and concepts may be realized in many alternative embodiments, either individually or in various combinations and sub-combinations thereof. Unless expressly excluded herein all such combinations and sub-combinations are intended to be within the scope of the present invention. Still further, while various alternative embodiments as to the various aspects and features of the invention, such as alternative materials, structures, configurations, methods, devices, software, hardware, control logic and so on may be described herein, such descriptions are not intended to be a complete or exhaustive list of available alternative embodiments, whether presently known or identified herein as conventional or standard or later developed. Those skilled in the art may readily adopt one or more of the aspects, concepts or features of the invention into additional embodiments within the scope of the present invention even if such embodiments are not expressly disclosed herein. Additionally, even though some features, concepts or aspects of the invention may be described herein as being a preferred arrangement or method, such description is not intended to suggest that such feature is required or necessary unless expressly so stated. Still further, exemplary or representative values and ranges may be included to assist in understanding the present invention however, such values and ranges are not to be construed in a limiting sense and are intended to be critical values or ranges only if so expressly stated.
• To distinguish the characteristics of the present invention from a current state of the art air brake system.FIG. 1 provides a partial schematic representation of a prior artair brake system100. The priorart brake system100 includes a primary air reservoir112 (typically for supplying a rear or trailer brake circuit) and secondary air reservoir114 (typically for supplying a front or tractor brake circuit). The primary andsecondary air reservoirs112,114 supply pressurized air to apply a set of frontservice brake assemblies116aand rearservice brake assemblies116b,and for releasing a set ofspring brake assemblies118. A set ofair lines119 communicate the pressurized air from thereservoirs112,114 to the brake assemblies116a,116b,and118.
• Service brakes generally refer to the brake assembly located on the axles of a commercial vehicle, which are actuated via the application of pressurized air, as is known in the art. The spring brakes generally refer to the brake assembly located on the axles that utilizes a spring to apply the vehicle's parking brakes. Air pressure is used to keep the spring compressed and the parking brakes released, as is known in the art.
• Theair brake system100 may also include abrake valve120 and aparking control valve122. Thebrake valve120 includes afoot pedal124, which opens the valve when the pedal is depressed. When open, thebrake valve120 allows pressurized air to flow from thereservoirs112,114 to arelay valve126 for actuating the service brakes, as is known in the art. Theparking control valve122, which may be opened manually, allows pressurized air to flow fromreservoirs112,114 to arelay valve128 for releasing the parking brakes, as is known in the art. A typical prior art air brake system may also include a variety of additional valves and components, as is known in the art. For example, tractor protection valves, quick release valves, spring brake valves, etc. are often employed. These valves and components are known in the art and are omitted from the discussion and illustration of the prior art and exemplary embodiments of the present invention for simplicity. The brake system according to the present invention, however, may utilize these and other valves and components.
• FIG. 2 illustrates an exemplary embodiment of apneumatic brake system150 according to the present invention. Similar to the prior artpneumatic brake system100 ofFIG. 1, the pneumatic brake system embodiment inFIG. 2 may include aprimary air reservoir152 andsecondary air reservoir154 to supply pressurized air for applying a set of frontservice brake assemblies156aand rearservice brake assemblies156b,and for releasing a set ofspring brake assemblies158. In the context of this invention, control or pilot air generally refers to a pneumatic signal for opening or closing a pneumatically actuated valve, while supply or delivery air generally refers to the pressurized air routed by valves and used to apply or release a terminal device, such as a spring brake or service brake.
• Theair brake system150 may also include abrake valve160 having afoot pedal164, which opens the valve when the pedal is depressed. Thebrake valve160 communicates with theprimary air reservoir152 and thesecondary air reservoir154 viaair lines166 and168, respectively. When open, thebrake valve120 allows pressurized air to flow fromreservoirs152,154 to theservice brake assemblies156a,156bviaair lines170 and to the rearservice brake assemblies156bviaair lines172 and174 for actuating the service brakes. A relay valve176 (FIG. 2) may be installed between the rearservice brake assemblies156band thebrake valve160 such that the air from the brake valve acts as control air for the relay valve, as is known in the art. Theair lines172 and174 communicate with a two-way check valve178 mounted to the control port of therelay valve176. Thus, air from the reservoir with the higher air pressure exits the check valve to apply therear service brakes156b.
• Thepneumatic brake system150 inFIG. 2 replaces thepark control valve122 of theprior art system100 ofFIG. 1 with avalve arrangement200 that may perform the work brake control, park brake control, or both parking brake and service work brake control.
• FIG. 3 is a schematic representation of an exemplary embodiment of avalve arrangement200 according to the present invention. For ease of explanation, thevalve arrangement200 may be described in two sections: a servicework brake section202 and apark brake section204. The servicework brake section202 includes afirst valve206 and asecond valve208 within ahousing209. Thehousing209 may allow thefirst valve206 and thesecond valve208, or the functionality of the first and second valve, to be consolidated within single unit, thus reducing the number of components and plumbing within thepneumatic brake system150.
• Thefirst valve206 is adapted to open in response to an electronic signal and close when the electronic signal is discontinued. For example, thefirst valve206 may be an electric control valve or a solenoid valve. In the exemplary embodiment ofFIG. 3, thefirst valve206 is a three-way, two-position, normally closed to delivery, normally open to exhaust, solenoid valve. However, other electrically controllable valves or pneumatic valves may be used, including, but not limited to, piezoelectric valves and micro machine valves.
• Thefirst valve206 includes apneumatic inlet210, apneumatic outlet212, and anexhaust port214. The two operational positions or modes of theelectric control valve206, are null or closed, and energized, delivery or open. When energized, thefirst valve206 allows air flow through the valve from theinlet210 to theoutlet212. When closed, thefirst valve206 closes the path from theinlet210 to theoutlet212, but opens the path from theoutlet212 to theexhaust port214. Thus, when thefirst valve206 is closed, any delivery air immediately downstream from the first valve may vent out of theexhaust port214.
• Thesecond valve208 is adapted to open in response to a first pneumatic signal and remain open when or if the first signal is discontinued. Further, thesecond valve208 may be adapted to close in response to receiving a second pneumatic signal and remain closed when or if the second signal is discontinued. Thus, thesecond valve208 may be a pneumatic latching valve. In the exemplary embodiment ofFIG. 3, thesecond valve208 is a three-way, two position, normally closed to delivery, normally open to exhaust, air-piloted latching valve with an automatic return to close feature, such as for example a spring return. Other valve types, styles, or models, however, may be employed. The automatic return to close capability of thesecond valve208 will automatically move the valve from the delivery position to the closed position as supply pressure at aninlet220 is reduced to a predetermined minimum. This capability greatly reduces the chance of the vehicle rolling between the time that air pressure is declining and the time that the park brakes are applied autonomously (i.e. pneumatically fail safe). The minimum can be influenced by selection of the spring installed, for example. An example of a suitable valve is a Bendix PP-5 Push-Pull Type Control Valve, adapted to be air-piloted. Other valve variants may also be used forsecond valve208.
• Thesecond valve208 includes aninlet220, anoutlet222, a firstcontrol signal port224, a secondcontrol signal port226, and anexhaust port228. Thesecond valve208 possesses the same two operational positions or modes as thefirst valve206, although the input signal for thesecond valve208 is pneumatic pressure, not electric current. When open, thesecond valve208 allows air to flow through the valve from theinlet220 to theoutlet222. When closed, thesecond valve208 closes the path from theinlet220 to theoutlet220, but opens a path from the outlet to theexhaust port228. Thus, when thesecond valve208 is closed, any delivery air immediately downstream from the second valve may vent out of theexhaust port228.
• Thefirst valve206 is in circuit communication with a device capable of sending or relaying an electronic signal. The device may be, for example, a manual, pneumatic, orelectrical switch unit229 and/or a controller or electronic processing unit230 (shown inFIG. 2 and 6 and discussed in detail below). Thebrake system150 includes a source of pressurized control air not shown) and a source of pressurized supply air (not shown). Theprimary air reservoir152 andsecondary air reservoir154 may serve as the sources for the control and supply air, or separate sources may be provided. The source of pressurized control air and the source of pressurized supply air may be a single source or may be separate sources of pressurized air. In the exemplary embodiment of thevalve arrangement200, the source of pressurized signal air and the source of pressurized supply air are the same source. In particular, apneumatic line231 from theprimary air reservoir112 and apneumatic line232 from thesecondary air reservoir114 connect to adouble check valve234. Thus, air from the reservoir with the higher air pressure will flow through the double check valve to supply the pressurized control air and supply air to thevalve arrangement200.
• Theinlet210 of thefirst valve206 and theinlet220 of thesecond valve208 communicate with the pressurized air exiting thedouble check valve234 viapneumatic lines236. The first pneumaticcontrol signal port224 of thesecond valve208 communicates with thepneumatic outlet212 of thefirst valve206 via apneumatic line236. Theoutlet222 of thesecond valve208 communicates with the rearservice brake assemblies156bvia apneumatic line240. As shown inFIG. 2, thepneumatic line240 may connect to an additionaldouble check valve241 which communicates with the control port of therelay valve176 to access the service brake system. Thus, the pneumatic signal from thesecond valve208 via thepneumatic line240 can function as a supply signal to actuate a terminal device such as theservice brakes156bor may function as a control signal to control another device, such as for example therelay valve176 or a brake valve actuator, that results in application of the service brakes. Furthermore, in the embodiment ofFIG. 2, the pneumatic signal from thesecond valve208 controls only therear service brakes156b. Thebrake system150, however, could also be configured to allow the pneumatic signal to operate thefront service brakes156a.
• An optional pressure regulating or reducingdevice242, such as for example, a pressure regulator, may be included in thework brake section202 to restrict the amount of air pressure being delivered through thesecond valve208 when open from exceeding a predetermined amount. For example, the full pressure available from the source of pressurized supply air may be 100 psi. Thepressure regulating device242 may reduce the pressure actually delivered to
• The secondcontrol signal port226 of thesecond valve208 communicates with a source of a pneumatic signal (described further below). Thus, while thefirst valve206 supplies a pneumatic signal to thesecond valve208 to open the second valve, a second pneumatic signal from a second source may be utilized to close thesecond valve208. The source of the second pneumatic signal may be any source capable of sending a pneumatic signal to actuate thesecond valve208, such as for example, an electronically or pneumatically actuated valve adapted to deliver a pneumatic signal.
• Thepark brake section204 of thevalve arrangement200 includes athird valve250, afourth valve252, and afifth valve254 within asecond housing255. Thus, as with thefirst housing209, thesecond housing255 may allow thethird valve250, thefourth valve252, and thefifth valve254, or the functionality of the valves, to be consolidated within single unit to, reduce the number of components and plumbing within thepneumatic brake system150. Thefirst housing209 and thesecond housing255 may form a single common housing for both the servicework brake section202 and thepark brake section204. Thefirst housing209 and thesecond housing255, however, may be separate housings forming separate assemblies. The separate assemblies, however, may be connected in a fixed manner, for example by one or more fittings, such that the first andsecond housing209,255 form a single assembly.
• The third andfourth valves250,252 are substantially similar to thefirst valve206 of the servicework brake section202 and thefifth valve254 is substantially similar to thesecond valve208 of the servicework brake section202. Thus, thethird valve250 includes apneumatic inlet256, apneumatic outlet258, and anexhaust port260 and thefourth valve252 includes apneumatic inlet262, apneumatic outlet264, and anexhaust port266. Further, thefifth valve254 includes aninlet268, anoutlet270, a firstcontrol signal port272, a secondcontrol signal port274, and anexhaust port276. The valves of thepark brake section204 possess the same two operational positions or modes as the valves of the servicework brake section202.
• The third andfourth valves250,252 are in circuit communication with a device capable of sending or relaying an electronic signal. For example, the device may include a manual, pneumatic, or electrical switch unit, a controller or an electronic processing unit, such as for example theswitch unit229 and theprocessing unit230 ofFIG. 2.
• Thepneumatic inlet256 of thethird valve250, thepneumatic inlet262 of thefourth valve252 and theinlet268 of thefifth valve254 communicate with pressurized air from thedouble check valve234 via thepneumatic lines236. For the third andfourth valves250,252, this air represents control air and for thefifth valve254, this air represents supply air.
• The firstcontrol signal port272 of thefifth valve254 communicates with thepneumatic outlet264 of thefourth valve252 via apneumatic line278. The secondcontrol signal port274 of thefifth valve254 communicates with thepneumatic outlet258 of thethird valve250 via apneumatic line280. Theoutlet270 of thefifth valve254 communicates withspring brake assemblies158 via apneumatic line282. Arelay valve283 may be installed between thespring brake assemblies158 and thefifth valve254 such that air from theparking brake section204 acts as control air for therelay valve283. Furthermore, the secondcontrol signal port226 of thesecond valve208 communicates with theoutlet264 of thefourth valve252 via apneumatic line284.
• The operation of thevalve arrangement200 can best be described in relations to the operation of a commercial vehicle, such as for example, a tractor trailer. In an initial state, the vehicle is parked with the parking brakes applied and the service work brakes not applied. The first, third, andfourth valves206,250,252 are not energized, and the second andfifth valves208,254 are closed, such that pressurized supply air is not supplied to either thespring brake assembly158 or theservice brake assembly156b.
• To unpark the vehicle, thefourth valve252 is energized, which supplies pressurized air in the form of a first pneumatic control signal to the firstcontrol signal port272 of thefifth valve254, and a second pneumatic control signal to the secondcontrol signal port226 of thesecond valve208. As a result, if the supply air pressure is greater than a predetermined amount, thefifth valve254 opens allowing pressurized supply air to flow through the fifth valve to the spring brake assembly22, releasing the spring applied parking brakes.
• At the same time, the second pneumatic control signal received by thesecond valve208 closes the second valve and opens the valve'sexhaust port226. As a result, any air in thepneumatic line240 vents to atmosphere. Air would be present in thepneumatic line240 if the service work brakes were applied. Thus, the act of releasing the parking brakes automatically releases the service work brakes, if applied. Because thesecond valve208 and thefifth valve254 latch into position, the first, third, andfourth valves206,250,252 can be de-energized without impacting the position of either latchingvalve208,254. The vehicle is now in a unparked mode. Thus, because the first, third, andfourth valves206,250,252 can be de-energized yet the vehicle may still be rolling with the parking brakes released, loss of electrical power or an electrical connection does not impact the status of the park brakes.
• While in the rollable, unparked mode, the driver may desire to stop the vehicle and apply the service work brakes. To do so, the driver stops the vehicle by a normal service brake application. In this position, thefifth valve254 is stilled latched in the open or delivering position, which keeps the park brakes released. Thethird valve250 and thefourth valve252 may be de-energized, which allows any air inpneumatic lines278 and280 to be relieved.
• Once stopped, to hold the vehicle still, the driver may engage the service work brakes by energizing thefirst valve206. As a result, thefirst valve206 allows pressurized air to flow through the first valve to the first pneumaticcontrol signal port224 of thesecond valve208 via thepneumatic line238. The first pneumatic control signal to thesecond valve208 opens the valve allowing pressurized, air to flow through the second valve to theservice brake assembly156bviaair line240, thus applying the brakes in a service work brake application.
• Because thesecond valve208 latches into the open position, the driver may de-energize thefirst valve206 without affecting the application of the service work brakes. Thus, if an electrical failure occurred while the service work brakes were applied, the service work brakes would remain applied despite the electrical failure. Thesecond valve208 does not change position as a result of discontinuing the electronic signal to thefirst valve206.
• Any of the air lines, such asair line240, may be routed redundantly (i.e. two or more lines) if desired. Furthermore, thesecond valve208 and thefifth valve254 can be optionally equipped with status sensor. Thus, in the event of afailure air line240, the vehicle can be parked autonomously or manually by energizing thethird valve250.
• To transition from a mode where the service work brakes are applied to the rollable, unparked mode, the driver would follow the same steps used to unpark the vehicle, as described above. In particular, the driver would energize thefourth valve252 as if desiring to remove the park brakes. Even if the park brakes are not applied, the act of energizing thefourth valve252 releases both the park brakes (if applied) and the service work brakes (if applied).
• When the vehicle has been stopped, the driver may wish to apply the park brakes to hold the vehicle still, as opposed to applying the service work brakes. To do so, the driver opens or energizes thethird valve250. Opening thethird valve250 allows pressurized air to flow through the third valve to the second pneumaticcontrol signal port274 of thefifth valve254 via thepneumatic line280. The second pneumatic control signal closes thefifth valve254, which discontinues the pneumatic supply signal from the fifth valve to thespring brake assembly158, thus applying the spring brakes. In addition, closing thefifth valve254 opens theexhaust port276 allowing pressurized air in thepneumatic line282 to vent to atmosphere.
• FIG. 4 is a second exemplary embodiment of thevalve arrangement300 according to the present invention. Thevalve arrangement300 ofFIG. 4 is substantially similar to thevalve arrangement200 ofFIG. 3 in that it includes a servicework brake section302 within afirst housing303 and apark brake section304 within asecond housing305. Thevalve arrangement300 also includes afirst valve306, asecond valve308, athird valve310, afourth valve312, and afifth valve314, which communicate with a source of pressurized control air and a source of pressurized supply air as described according to thevalve arrangement200 ofFIG. 3. Apressure reducing device315 may be included in thevalve arrangement400 to reduce the pressure delivered to theservice brakes156b.
• Thevalve arrangement300 ofFIG. 4, however, modifies the source of a second pneumatic control signal for the second valve308 (i.e. the pneumatic signal for closing the second valve). In thevalve arrangement200 ofFIG. 3, thefourth valve252 delivers the second pneumatic control signal to thesecond valve208. Thus, the pneumatic control signal that opens thefifth valve254 also closes thesecond valve208. In thevalve arrangement300 ofFIG. 4, the pneumatic control signal to close thesecond valve308 is the pneumatic supply signal from thefifth valve314. Therefore, when thefifth valve314 is open, it sends a pneumatic signal to the spring brake assembly to release the spring brakes while at the same time sending a pneumatic control signal to thesecond valve308 to close the valve, thus releasing the service work brakes, if applied.
• FIG. 5 is a third exemplary embodiment of avalve arrangement400 according to the present invention. Thevalve arrangement400 ofFIG. 5 includes a servicework brake section402 within ahousing403 that is substantially similar to the servicework brake section202 of the embodiment ofFIG. 3. In particular, the servicework brake section402 includes afirst valve404 adapted to open in response to an electronic signal and close when the electronic signal is discontinued. When open, thefirst valve404 delivers a pneumatic signal via anair line406.
• The servicework brake section402 also includes asecond valve408, which is adapted to open in response to first pneumatic signal and remain open when or if the first signal is discontinued. Further, thesecond valve408 is adapted to close in response to receiving a second pneumatic signal and remain closed when or if the second signal is discontinued. When open, thesecond valve408 delivers a pneumatic supply signal to a servicework brake assembly156bvia anair line410. Apressure regulating device411 may be included in thevalve arrangement400 to reduce the pressure delivered to the
• Thevalve arrangement400 ofFIG. 5, however, illustrates how the servicework brake section402 may integrate with a purely pneumaticpark control valve412, such as for example, thepark control valve122 of the prior art brake system ofFIG. 1. Theparking control valve412 may be a push-pull, manually operable on/off valve with an integral double check valve, however, other variants are possible. An example of a suitable park control valve is PP-DC Park Control Valve available from Bendix Commercial Vehicle Systems, LLC.
• Theparking control valve412 communicates with theprimary air reservoir112 and the secondary air reservoir114 (seeFIG. 2) viaair lines414 and416, respectively. When the parking control valve is open, the valve delivers pressurized air from either theprimary reservoir112 orsecondary reservoir114, whichever is higher pressure.
• When open, theparking control valve412 delivers a pneumatic supply signal to thespring brake assemblies158 via anair line418 to release the park brakes. Thepark control valve412 may also communicate with thesecond valve408 viaair line420 to supply a pneumatic supply signal to close thesecond valve408, similar to the arrangement ofFIG. 4.
• Referring toFIG. 6, thecontroller230, as discussed previously, may be capable of sending or relaying an electronic signal to thevalve arrangement200 for engaging and/or disengaging the work brake function and/or parking brake functions. Thecontroller230 may be, for example a vehicle electronic control unit (ECU), such as an antilock brake ECU, in communication with avoltage source428 for supplying power to the controller. Thecontroller230, however, can be a wide variety of control devices, such as for example, a controller integral to a valve.
• In an exemplary embodiment, thecontroller230 may include one ormore inputs429 for receiving input data or signals indicative of the status or condition of the vehicle and/or operator from one or more input sources430. The one ormore input sources430 may include a wide variety of input devices. For example, a firstmanual switch432 may be provided to send a signal to thecontroller230 to engage and/or disengage the park brakes on the tractor and trailer and a second manual switch434 may be provided to send a signal to the controller to engage and/or disengage the work brakes. Furthermore, one or more sensors and/or switches436 may be provided capable of sending signals to thecontroller230 indicative of, for example, an operating condition or status of the vehicle, the status, intent, or request of the driver/operator, vehicle diagnostic information, or any other relevant information.
• Based on the input signals, thecontroller230 may include one ormore outputs437 for automatically delivering control signals to thevalve arrangement200 and/or one or moreother output devices438. The one ormore output devices438 may include for example, but not be limited to, devices capable or actuating or controlling an engine throttle, a vehicle transmission, a speed governor, and status enunciators (indicator lights, displays, audible devices, etc).
• Thecontroller230 may include control logic, which may be stored inmemory440, and a processor for applying thelogic442. Thememory440 may or may not be integral to thecontroller230. Thecontroller230 may implement the control logic to analyze the information from theinput devices430 in order to determine a proper course for action, which may include intervening in the operation of the vehicle to automatically enable, disable, or control a vehicle system or device.
• FIG. 7 presents a flowchart of an exemplary embodiment of the logic of thecontroller230. The logic may include the steps of inferring the status of thevehicle450, inferring the status of the driver oroperator452, enabling appropriate vehicle functions454, interring the driver/operator intent456, checking the plausibility of the driver/operator intent458, activating the driver-intendedfunction460, enforcing afailsafe function462, and enunciating thestatus464. The logic may be configured to continually repeat the steps while the controller/vehicle is powered on.
• In the step of intoning the status of thevehicle450, thecontroller230 may receive data from the one ormore input sources430, and based on the data received, the controller may determine whether the vehicle is in a SAFE or UNSAFE status. The data from the one ormore input sources430 may include, but not be limited to, vehicle speed, engine rotational speed, transmission gear engaged, vehicle voltage, and air brake system supply pressure (park brake circuit air pressure and service brake circuit air pressure). One of ordinary skill in the art will appreciate that thecontroller230 may utilize a wide variety of data configured in a wide variety of ways. For example, thecontroller230 may receive an indication of vehicle speed directly from a vehicle speed sensor or may infer/determine vehicle speed from data indicative of engine rotational speed and throttle position.
• A SAFE status and an UNSAFE status may depend on a variety of factors, such as user preference, vehicle configuration, vehicle options, and the specific embodiment of the present invention being employed. These factors may be predetermined and stored inmemory440 or may be inferred from input data received.
• A SAFE vehicle status may include, but not be limited to, a determination that one or more vehicle systems are diagnostically sound (e.g. air pressure and electrical integrity of an air brake system are sufficient), the vehicle being stopped or moving very slowly, and the auxiliary and/or Power-Take-Off functions being turned off or properly stowed. Thus, an UNSAFE vehicle status may include, but not be limited to, one or more systems or components being diagnosed as faulty, the vehicle being in motion, and the auxiliary and/or Power-Take-Off functions (e.g. a refuse compactor, passenger doors, etc.), not being disabled or properly stowed. One of ordinary skill in the art will appreciate that the combination of input data indicative of a SAFE or UNSAFE status may be predetermined at the user's discretion and stored in memory to be referenced by thecontroller230 to make the status determination.
• If the vehicle status is determined to be UNSAFE, thecontroller230 may enforce afailsafe function462. Failsafe functions may include any action taken by thecontroller230 to alter the vehicle status from a state determined to be unsafe or inappropriate to a state determined by the controller to be safer or more appropriate. For example, thecontroller230 may prohibit an unsafe stationary vehicle from moving, may automatically brake a vehicle rolling away without a driver present, may place the vehicle into a Limp-To-Roadside mode by allowing timed durations of low-speed maneuvers to move the vehicle from an unsafe or undesired location, may prohibit brake drag that could lead to risk of fire, may enunciate the unsafe condition while the vehicle is moving, and may disable one or more functions when stopped. Other failsafe functions, however, are possible and may be implemented by thecontroller230.
• The failsafe functions may be effectuated in a variety of ways. Some possible actions by thecontroller230 in order enforce a failsafe function include, but are not limited to, automatically applying the park brakes, prohibiting, manual release of the park brakes, automatically applying the work brake, automatically releasing the work brake, prohibiting engagement of a non-neutral transmission gear, disabling a vehicle starter motor, disabling a vehicle throttle, operating a speed governing device, and disabling an auxiliary function or Power-Take-Off function.
• If thecontroller230 determines that the vehicle is in a SAFE status, then the controller may execute the step of inferring thedriver status452. One of ordinary skill in the art, however, will appreciate that the logic steps illustrated inFIG. 7, may be accomplished in a different order than presented. The steps are presented in the order shown inFIG. 7 for convenience only.
• Thecontroller230 may receive data from one or more input sources430. Based on the data received, thecontroller230 may determine whether the driver is QUALIFIED or UNQUALIFIED. Inferring the driver status may include identifying, that the operator is present and is authorized to operate the vehicle. The data received from the one ormore input sources430 may be indicative of, but not be limited to, vehicle door status, ignition key status, driver restraint status, the status of various switches, the control status of various vehicle systems, and time histories for each of the status mentioned.
• A QUALIFIED driver status may include, for example, but not be limited to, the driver being present in the vehicle, which may be indicated by a seat switch or driver restraint switch, the driver being in control of the vehicle (i.e. driver control input sensed), the driver successfully enabling the vehicle (e.g. ignition has been keyed-on), and the driver passing an identification verification (e.g. a proper identification badge has been swiped or a proper code has been entered). Other criteria, however, may also be used to define a QUALIFIED status. For example, the identification verification may include the qualification level of an individual operator (e.g. driver-in-training, fully trained, service personnel). An UNQUALIFIED status, therefore, may be defined as a failure to meet one or more criteria for a QUALIFIED status.
• If thecontroller230 determines that the driver status is UNQUALIFIED, then the controller may enforce afailsafe function462. If thecontroller230 determines that the driver status is QUALIFIED, then the controller may execute the step of enablingappropriate functions454. Based on the vehicle status and driver status inferred insteps450 and452, respectively, thecontroller230 may enable only those functions determined to be APPROPRIATE and disable those functions determined to be INAPPROPRIATE. Thecontroller230 may enable or disable any vehicle functions which it may control. Examples of functions thecontroller230 may control include, but are not limited to, the park brake function, the work brake function, transmission gear change, and speed governing.
• As an example, for a SAFE vehicle status and a QUALIFIED driver status, thecontroller230 may enable the work brake arrangement. As discussed above, a SAFE vehicle status may include a verification that the vehicle is stopped or only moving slowly and that the air brake system supply pressure is adequate. Thus, the overall condition of the vehicle may be appropriate for utilizing a work brake function. Furthermore, the functions considered appropriate may depend on the level of qualification of the operator. For example, service personnel, tow truck drivers, and drivers-in-training may have different vehicle functions enabled for them, thus thecontroller230 may offer different operational capabilities based on the level of qualification of the operator. As shown by the dashed line inFIG. 7, inappropriate functions may be disabled via the step of enforcing afailsafe function462 as described above.
• For those APPROPRIATE functions, thecontroller230 may execute the step of inferring the driver'sintent456. Thecontroller230 may receive data from the one ormore input sources430 that may be indicative of driver actuation. For example, a door switch may indicate that the driver has opened or closed the door, or a driver restraint switch may indicate that the driver has fastened or released the seat belt. Based on data indicative of driver actuation, thecontroller230 may infer the driver's intent. Examples of the driver intent may include, but are not limited to, the intent to leave the vehicle, the intent to move the vehicle, the intent to park the vehicle, and the intent of the driver to work brake the vehicle. Thus, in order to infer driver intent, thecontroller230 may, for example, utilize data indicative of the door being opened or closed, the ignition key being turned on or off, the engine being started or stopped, the park brake switch being actuated, and a certain transmission gear being selected.
• Thecontroller230 may infer that the driver's intent is UNSAFE. For example, combinations of driver intent that may be deemed UNSAFE may include, but not be limited to, the driver intending to park a moving vehicle, the driver intending to work brake a vehicle while the park brakes are applied, or the driver intending to leave a moving vehicle. If thecontroller230 determines that the driver's intent is UNSAFE, the controller may enforce afailsafe function452.
• If thecontroller230 determines that the driver's intent is SAFE, then the controller may execute the step of checking the plausibility/safety of the driver'sintent458. Thecontroller230, thus, may cross check the inferred intent of the driver as a plausible request in order to rule out erroneous sensor readings not able to be detected. In addition, thecontroller230 may execute a safety check that may include, but not be limited to, checking for switch or sensor failure, checking for electronic control unit failure, checking for low system voltage or air pressure, and checking for failure of a communication link.
• Furthermore, during the step of checking the plausibility of the driver's intent, thecontroller230 may check for attempts by the driver to defeat/override the system, such as for example, the driver taping a door switch to indicate that it is closed when the door is actually open. As an example, thecontroller230 may infer that a qualified driver intends to move the vehicle by selecting a forward gear and opening the throttle. The intent of the driver may be cross-checked with the status of the park brake and the work brake. If the park brake or work brake are engaged, thecontroller230 may determine that the driver's intent is not plausible (e.g. the vehicle should not/cannot be operated when the park brake or work brake are engaged). As a result, thecontroller230 may disable the throttle until the driver releases the park brake or work brake. Thus, if thecontroller230 determines that the driver's intent is not plausible, then the controller may enforce afailsafe function462, as described above. Alternatively, thecontroller230 may automatically release the park brake or work brake if input data indicates additional conditions are met, such as for example, the seat is occupied, the door is shut, the restraint is buckled, the throttle demand is high (possibly indicating an emergency condition).
• If thecontroller230 determines that the driver's intent is plausible, then the controller may activate the driver-intendedfunctions460. Driver-intended functions may be any functions that the driver/operator would request the vehicle to perform that thecontroller230 may discern or have a priori knowledge of. Driver-intended functions that thecontroller230 may potentially activate (i.e. allow the driver to manually request) may include, but not be limited to, applying/releasing the park brake, applying/releasing the work brake, engaging a non-neutral transmission gear, actuating the vehicle throttle, operating an auxiliary function or Power-Take Off function, and cranking the starter motor.
• Thecontroller230 may also send an output signal to enunciate the status of the vehicle during any of the steps performed by the controller. Thus, output devices capable of enunciating the vehicle status may be provided in communication with thecontroller230. Status enunciators may include, but not be limited to, LCD text messages, indicator lights, and audible devices. For example, operational status indicators, such as a park brake indictor light or a work brake indicator light, may be provided. Thecontroller230 may toggle the operational status indicators on and off with each successful state transition (e.g. park brake is released), thus the meaning of the indicators may be self-teaching to the operator/driver. Audible indicators, such as for example a pleasant chime, may also accompany visual indicators or stand alone to reassure the operator that a successful operation has been completed.
• In addition, fault indicators, such as a park brake fault light, a work brake fault light arid/or a Limp-to-Roadside indicator light may be provided. The fault indicators may be tested during each key-on of the vehicle, but may generally remain off unless thecontroller230 detects a fault or enters the Limp-to-Roadside mode. Audible indicators (e.g. a disconcerting buzz) may accompany the visual fault indicators or stand alone to reinforce that some risk has been detected.
• The invention has been described with reference to the preferred embodiments. Modification and alterations will occur to others upon a reading and understanding of this specification. It is intended to include all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (28)

1. A controller for an automatic work brake on a vehicle, the controller comprising:

at least one input receiving at least one input signal indicative of a status of the vehicle representing a speed of the vehicle and a service brake pedal position;

a processor determining, based on the input signal, whether to automatically apply the automatic work brake; and

an output delivering a control signal for automatically engaging the work brake based on the determination of the processor.

2. The controller for an automatic work brake on a vehicle as set forth inclaim 1, wherein:

the at least one input signal indicative of a status of the vehicle represents at least one of a driver present, a fault status of a vehicle system, a rotational speed of an engine of the vehicle, a throttle demand of the engine of the vehicle, a transmission gear engaged, a voltage of the vehicle, and a supply pressure of a vehicle brake system.

3. The controller for an automatic work brake on a vehicle as set forth inclaim 1, wherein:

the processor determines if the vehicle is in one of a SAFE status and an UNSAFE status based on the at least one input signal.

4. The controller for an automatic work brake on a vehicle as set forth inclaim 3, wherein:

the processor determines the vehicle is in the SAFE status if the speed of the vehicle is less than a predetermined speed and the service brake pedal is depressed.

5. The controller for an automatic work brake on a vehicle as set forth inclaim 4, wherein:

if the processor determines the vehicle is in the SAFE status, the processor determining to automatically apply the work brake.

6. The controller for an automatic work brake on a vehicle as set forth inclaim 4, wherein:

if the processor determines the vehicle is in the SAFE status, the processor determining to automatically release the work brake if a throttle demand of the engine is above a predetermined level.

7. The controller for an automatic work brake on a vehicle as set forth inclaim 3, wherein:

if the work brake is applied, the processor determines the vehicle is in the UNSAFE status if a fault status of the vehicle system is faulted; and

if the processor determines the vehicle is in the UNSAFE status, the processor enforcing a failsafe function.

8. The controller for an automatic work brake on a vehicle as set forth inclaim 1, wherein:

if the processor determines to automatically apply the work brake, the output delivers a control signal for activating a valve to engage the work brake.

9. A system for automatically applying a work brake, the system comprising:

a first valve controlling pressure delivered to a service brake;

a controller, including:

at least one input signal indicative of a status of the vehicle representing a speed of the vehicle and a service brake pedal position;

a processor determining, based on the input signal, whether to automatically apply the automatic work brake; and

an output delivering a control signal to the first valve, for automatically engaging the service brake as the work brake, based on the determination of the processor.

10. The system for automatically applying as work brake as set forth inclaim 9, the system further including:

a second valve including an outlet fluidly communicating with the service brake.

11. The system for automatically applying a work brake as set forth inclaim 10, wherein:

the controller delivers an electronic control signal to the first valve; and

the first valve delivers a pneumatic open control signal to the second valve.

12. The system for automatically applying a work brake as set forth inclaim 11, wherein:

the second valve is set to an open state for delivering fluid pressure to the service brake upon receiving the pneumatic open control signal from the first valve.

13. The system for automatically applying a work brake as set forth inclaim 12, wherein:

the second valve latches in the open state and remains in the open state even after the pneumatic open control signal from the first valve ceases; and

the service brake acts as the work brake While the second valve is latched in the open state.

14. The system for automatically applying a work brake as set forth inclaim 12, wherein:

the second valve is set to a closed state for not delivering fluid pressure to the service brake upon receiving a pneumatic close control signal from as fourth valve;

the second valve latches in the closed state and remains in the closed state even after the pneumatic close control signal ceases.

15. The system for automatically applying a work brake as set forth inclaim 14, wherein:

the outlet of the fourth valve fluidly communicates with a closing control port of the second valve.

16. The system for automatically applying a work brake as set forth inclaim 14, wherein:

the control signal delivered by the controller to the first valve is a first electronic control signal;

the controller also delivers a second electronic control signal the fourth valve based on the determination of the processor; and

the respective electronic control signals delivered to the first valve and the fourth valve, based on the determination of the processor, control the first valve and the fourth valve for automatically engaging and releasing the service brake as the work brake.

17. The system for automatically applying a work brake as set forth inclaim 6, wherein:

the processor determines to automatically engage the service brake as the work brake if the service brake pedal is in a depressed position and the speed of the vehicle is less than a predetermined speed.

18. The system for automatically applying a work brake as set forth inclaim 17, wherein:

the processor determines to automatically release the work brake if a throttle demand of the engine is above a predetermined level.

19. The system for automatically applying a work brake as set forth inclaim 16, wherein:

if the processor determines to automatically apply the service brake as the work brake, the controller delivers the first electronic control signal to the first valve for setting the first valve to an open state;

while in the open state, the first valve delivers a pneumatic control signal to the opening control port of the second valve for setting the second valve to an open state; and

while in the open state, the outlet of the second valve fluidly communicates with the inlet of the second valve so that pressure from the inlet of the second valve is fluidly communicated to the service brake for actuating the service brake.

20. The system for automatically applying, a work brake as set forth inclaim 19, wherein:

if the processor determines to automatically release the service brake as the work brake, the controller ensures the first electronic control signal is no longer delivered to the first valve while delivering the third electronic control signal to the fourth valve for setting the fourth valve to an open state;

while in the open state, the fourth valve delivers a pneumatic control signal to the closing control port of the second valve for setting the second valve to a closed state; and

while in the closed state, the outlet of the second valve does not fluidly communicate with the inlet of the second valve so that pressure from the inlet of the second valve is not fluidly communicated to the service brake so the service brake is not actuated.

21. A controller for an automatic work brake on a vehicle, the controller comprising:

at least one input receiving at least one input signal indicative of a status of the vehicle representing a speed of the vehicle and a service brake pedal position;

a processor determining an intent of the driver, based on the at least one input signal, to automatically apply the automatic work brake when the speed of the vehicle is less than a predetermined speed and the service brake pedal is depressed; and

an output delivering a control signal for automatically engaging the work brake based on the intent of the driver.

22. The controller for an automatic work brake on a vehicle as set forth inclaim 21, wherein:

the processor determines the intent of the driver is to automatically release the work brake if the at least one input signal indicates a throttle demand of the engine is greater than a predetermined level.

23. A system for automatically at least one of applying and releasing a work brake, the system comprising:

means for determining whether to at least one of automatically apply and release the work brake; and

means for controlling pressure delivered to a service brake, the pressure being continuously fluidly communicated to the service brake for causing the service brake to act as the work brake when it is determined to automatically apply the work brake, and the pressure being not fluidly communicated to the service brake for releasing the work brake when it is determined to automatically release the work brake.

24. The system for automatically at least one of applying and releasing a work brake as set forth inclaim 23, further including:

means for determining an intent of a driver;

the means for determining whether to automatically at least one of apply and release the work brake being based on the intent of the driver.

25. A method controlling an automatic work brake on a vehicle, the method comprising:

receiving at least one input signal indicative of a status of the vehicle representing at least one of a speed of the vehicle and a service brake pedal position;

determining to automatically apply the automatic work brake based on the at least one input signal; and

delivering a control signal for automatically applying the work brake based on the determination to automatically apply the automatic work brake.

26. The method controlling an automatic work brake on a vehicle as set forth inclaim 25, further including:

determining an intent of the driver based on the at least one input signal.

27. The method controlling an automatic work brake on a vehicle as set forth inclaim 25, wherein the step of determining to automatically apply the automatic work brake includes:

determining to automatically apply the automatic work brake when the speed of the vehicle is less than a predetermined speed and the service brake pedal is depressed.

28. The method controlling an automatic work brake on a vehicle as set forth inclaim 25, further including:

determining to automatically release the automatic work brake when a throttle demand of the engine is above a predetermined level.

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