US20020005780A1 - Anti-lock brake system for a vehicle, such as a truck or a trailer, including back-up alarm and/or lamps - Google Patents

Abstract

An anti-lock brake system (ABS) or an electro-pneumatic brake system (EBS) for a vehicle, such as a trailer, is used to perform a function of the vehicle when it is in reverse such as sounding an audible back-up alarm and/or lighting a back-up lamp. A sensor member is mounted on an axle of the vehicle is used to determine the speed of rotation of the wheel and to determine the direction of rotation of the wheel by sensing an exciting ring which rotates with the wheel. A controller processes information from the sensor member regarding the wheel speed and the direction of wheel rotation. A circuit causes the function on the vehicle to be performed when it is activated by the controller.

Description

• This application claims the priority of provisional application Serial No. 60/171,741, filed on Dec. 22, 1999, and entitled “Sensing System For a Trailer Wheel”.[0001]
BACKGROUND OF THE INVENTION
• This invention is generally directed to an anti-lock brake system (ABS) or an electro-pneumatic brake system (EBS) for a vehicle, such as a trailer, which is used to perform a function of the vehicle when it is in reverse. More particularly, the invention contemplates an ABS or EBS which is used to power an audible back-up alarm and/or a back-up lamp when a trailer is in reverse.[0002]
• Historically in the North American trucking industry, there has been a limited number of electrical connections available between a tractor and a trailer. One connector is available. This is defined by the Society of Automotive Engineers (SAE) J560 standard and the following circuits are available:[0003]
• 1 White Ground return to tractor[0004]
• 2 Black Clearance, side marker and identification lamps[0005]
• 3 Yellow Left turn signal and hazard lamps[0006]
• 4 Red Stop lamps (and anti-lock brake system power)[0007]
• 5 Green Right turn signal and hazard lamps[0008]
• 6 Brown Tail and license plate lamps[0009]
• 7 Blue Auxiliary[0010]
• [0011]Pin7 has been considered a general purpose pin which was used as the particular vehicle operator required. For example,Pin7 can be used to light an interior lamp (dome lamp) in the trailer or to light a back-up lamp. Two disadvantages become apparent. First, if the owner wanted both back-up lamps and dome lamps, this could not be accommodated. Second, since tractors and trailers are constantly intermixed, incompatibility becomes an issue. For example, if a tractor is wired to turn on trailer back-up lamps automatically, this would just light the interior lamps on a trailer which used the auxiliary circuit for this purpose.
• Since March of 1997 for tractors, and since March of 1998 for trailers, the use of this circuit on[0012]Pin7 has largely been standardized to supply power, but only when the ignition is switched on. This circuit powers the ABS on the trailer. The circuit onPin7 may also be utilized by other devices. This has helped to standardize the use of this circuit. The downside, however, is that there is now no circuit available for functions.
• It should be noted that if an operator wants to have an additional connector to handl one or more auxiliary functions, this is entirely possible. This works well for a particular tractor-trailer combination, or at best within a particular small fleet. It is not a mainstream solution because tractors and trailers are constantly intermixed. Even if tractors and trailers always stayed within the same fleet, it would still be practically impossible to re-equip an entire large fleet which could easily have more than ten thousand trailers.[0013]
• Concentrating in particular on audible back-up alarms and back-up lamps, these are very desirable to have on trailers. There is an obvious advantage when backing up at night. An audible back-up alarm is very desirable, even during daytime when backing up in areas busy with pedestrian traffic. A construction site is a good example of this type of environment. An alarm at the back of the trailer is preferable to an alarm mounted on the tractor which may be forty-five feet forward and may not be heard in a noisy environment.[0014]
• ABS technology provides a mechanism by which an audible back-up alarm and/or a back-up lamp can be practically and economically implemented on a trailer. It should also be noted that, in the future, more advanced brake controls known as Electro-pneumatic Brake Systems (EBS) may replace the basic ABS of today. EBS generally incorporate the ABS function and also require wheel speed sensors.[0015]
• As shown in FIG. 1, the wheel speed sensors provide wheel speed information to the electronic control module (ECM) of the anti-lock brake system. The ECM signals the pneumatic control module (PCM) of the anti-lock brake system to modify air pressure level at the brake chambers. The braking level is controlled so that the wheels continue to rotate, or at least rotate most of the time, even during heavy braking. The overall process is described in detail in numerous patents and in the pending U.S. patent application Ser. No. 09/306,921, which is commonly owned by the assignee herein.[0016]
• The current industry standard sensing mechanism uses a variable reluctance (VR) sensor together with a toothed ring which is fitted to the back of the wheel hub. The sensor consists of a magnet, a coil of wire and a metal pole piece, all of which are enclosed in a cylindrical casing of about 2½ inches long and ⅝ inches diameter. The toothed ring generally has 100 teeth.[0017]
• As the wheel rotates, magnetic flux through the coil in the sensor is present to a greater or lesser degree depending on whether a tooth is directly over the pole piece in the face of the sensor. This changing flux induces an alternating voltage in the coil which is approximately sinusoidal. The frequency is proportional to the speed of the wheel and the proportionality relationship is about 14 Hertz (cycles per second) per mph. The frequency signal is used by the ECM to determine the speed of the wheel. The amplitude of the signal is highly dependent on the gap between the face of the sensor and the toothed ring and it also increases with wheel speed. Generally the amplitude information is not used directly by the ECM.[0018]
• The sensor is located in a bore in a metal block which is welded to the axle behind the hub. A sleeve within the bore retains the sensor so that its face remains close to the toothed ring.[0019]
• The VR sensors do not measure “zero” speed. The VR sensors generate voltage in response to changing magnetic flux but the VR sensors do not respond to absolute flux levels. As such, the VR sensors cannot determine whether the pole of the sensor is opposite a tooth or a gap if the ring is stationary. Very slow rates of rotation, for example below one mile per hour depending on the sensor gap, do not generate enough alternating voltage for the ECM to determine that rotation is actually occurring.[0020]
• Passenger car ABS sensing technology sometimes uses “active” sensors. The active sensors have a semiconductor-type element to replace the coil in conventional VR sensors. This semiconductor-type element measures the actual level of magnetic flux, not a rate of change. These active sensors can measure close to “zero” speed as the active sensors respond to each change from a tooth to a gap, or vice versa, regardless of speed. For active sensors, the toothed ring can be replaced by a circular multi-pole magnet which may be considered to be an exciting ring.[0021]
• In addition to the sensing element, active sensors also require integrated electronic circuitry to amplify the signal to reasonable levels for transmission to the ECM. Hence, active sensors use several “active” electronic components. Either a two or a three-wire connection to the ECM is required. An approximate square wave signal with levels of zero and five volts would be typical for a three-lead design. The three leads are power, ground and signal. For a two-lead design, two different current levels with typical values of seven mamps and fourteen mamps would be used. The two leads are power and ground, with current variation being sensed by the interface electronics.[0022]
• From a functional perspective, “zero” speed sensing of itself, does not provide a significant advantage for a simple trailer ABS product. In certain circumstances, however, this active technology provides implementation advantages. Also, as will be discussed here, and in related patent applications owned by the assignee herein, this technology allows easier implementation of certain features which can be added to a basic trailer ABS product.[0023]
• As noted, prior art ABS have wheel speed information available to them. Prior art ABS do not have information as to whether rotation is forward or reverse.[0024]
• In the production machine industry, such as forging machines, reverse speed sensing arrangements have been used. Reverse speed sensing is frequently implemented using a pair of sensors with a technique known as quadrature. Essentially, the sensors are placed an integral number of tooth spacings away plus one-fourth of a tooth spacing. If a tooth spacing is considered to be 360 degrees, then the one-fourth corresponds to 90 degrees. By checking whether a positive edge follows a positive edge, or whether a negative edge follows a positive edge, the direction of rotation of the wheel can be detected. Techniques for doing this are well-known to those familiar with the state of the art.[0025]
• FIG. 2 is a suitable logic circuit which implements this function. Signals A and B show two square waveforms in quadrature. Signals A and B are assumed to originate from two separate sensors appropriately spaced on the toothed ring. Square waves like those shown can be produced directly by active sensors. A high level represents when the approximately sinusoidal voltage from the sensor is positive, and a low level represents when the approximately sinusoidal signal from the sensor is negative. Suitable signal conditioning circuits for VR sensors are in common use and are well-known to those skilled in the art.[0026]
• Assuming suitable square wave signals, A and B, the circuit of FIG. 2 provides a possible implementation of the electronics required to interpret the quadrature signals. The flip-flop clocks the information from input to output when there is a positive edge at its clock input. Thus, the flip-flop clocks on positive edges of the A waveform. It will be seen that the output C is low for forward rotation, and the output C is high for reverse rotation. The C line is fed to a controller which operates under stored program control. The stored program makes the decision to provide power to the alarms and lamps, or for other purposes.[0027]
• While conventional VR sensors are acceptable for determining direction, some issues arise. First, two separate sensors are required. Second, precise mounting of the sensors are required, particularly in relation to each other. There is also the issue that two separate signal conditioning circuits are required. Speed sensitivity of the output of a VR sensor is also a concern. At a very low speed, there is only a very low amplitude signal and it would be desirable to power the alarm and/or lamps, even when moving at very slow speed.[0028]
• The present invention provides novel structure for sensing the direction of the trailer using ABS or EBS. Other features and advantages of the present invention will become apparent upon reading the attached specification in combination with a study of the drawings.[0029]
OBJECT AND SUMMARY OF THE INVENTION
• A general object of the present invention is to provide an anti-lock brake system (ABS) or an electro-pneumatic brake system (EBS) for performing a function of a vehicle when the vehicle is in reverse.[0030]
• Another object of the present invention is to provide an ABS or EBS which is used to power an audible back-up alarm and/or a back-up lamp when the vehicle is in reverse.[0031]
• Briefly, and in accordance with the foregoing, the present invention discloses an ABS or EBS for a vehicle, such as a trailer or a truck, which activates a function on the vehicle, such as an audible back-up alarm and/or a back-up lamp, when the vehicle is reversing. A sensor member is mounted on an axle of the vehicle is used to determine the speed of rotation of the wheel and to determine the direction of rotation of the wheel by sensing an exciting ring which rotates with the wheel. A controller processes information from the sensor member regarding the wheel speed and the direction of wheel rotation. A circuit causes the function on the vehicle to be performed when it is activated by the controller.[0032]
BRIEF DESCRIPTION OF THE DRAWINGS
• The organization and manner of the structure and operation of the invention, together with further objects and advantages thereof, may best be understood by reference to the following description, taken in connection with the accompanying drawings, wherein like reference numerals identify like elements in which:[0033]
• FIG. 1 is a block diagram of a prior art anti-lock brake system;[0034]
• FIG. 2 is a prior art schematic for sensing direction;[0035]
• FIG. 3 is a block diagram of an anti-lock brake system (ABS) or an electro-pneunmatic brake system (EBS) which incorporates the features of the present invention;[0036]
• FIG. 4 is a side elevational view of a trailer and a partial side elevational view of a tractor on which the ABS or EBS which incorporates the features of the present invention is used;[0037]
• FIG. 5 is a partial cross-sectional view of a wheel mounting apparatus which includes a wheel speed sensor which incorporates the features of the invention;[0038]
• FIG. 6 is an enlarged section of FIG. 5;[0039]
• FIG. 7 is a perspective view of a portion of the wheel speed sensor;[0040]
• FIG. 8 is an enhancement circuit which is used in the present invention;[0041]
• FIG. 9 is an electronic schematic of an implementation of the present invention;[0042]
• FIG. 10 is a schematic of the overall implementation of the present invention; and[0043]
• FIG. 11 is a schematic of the schematic of the wheel speed sensor and ABS.[0044]
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT
• While the invention may be susceptible to embodiment in different forms, there is shown in the drawings, and herein will be described in detail, a specific embodiment with the understanding that the present disclosure is to be considered an exemplification of the principles of the invention, and is not intended to limit the invention to that as illustrated and described herein.[0045]
• A block diagram for an anti-lock brake system (ABS) or an electro-pneumatic brake system (EBS) for a[0046]trailer26 in accordance with the present invention is shown in FIG. 3. The present invention provides a wheel sensing arrangement, more specifically described with respect to FIG. 9, which provides speed and direction information to a controller, such as an electronic control module (ECM). Power (12 Volts) to the ECM is supplied frompin7 of theJ560 connector18 between thetractor16 and thetrailer26. The ECM controls a pneumatic control module (PCM) which controls the air brake mechanism on thetrailer26. The ECM also controls the function of circuitry, such as a back-up system which is used to sound an audible back-up alarm, which is performed using suitable means, and/or light a back-up lamp, as described herein. The ECM of the ABS or EBS signals the PCM of the ABS or EBS to modify air pressure level at the brake chambers. The braking level is controlled so that the wheels continue to rotate, or at least rotate most of the time, even during heavy braking. The overall process is described in detail in numerous patents and in the pending U.S. patent application Ser. No. 09/306,921, which is commonly owned by the assignee herein and which is incorporated by reference. The present invention uses a wheel speed anddirection sensor20 which is mounted in the end of anaxle22 of awheel mounting apparatus24 of thetrailer26 as described herein.
• The[0047]wheel mounting apparatus24 generally includes theaxle22, awheel hub assembly28 and an air brake mechanism. The air brake mechanism is of known construction and as such is not described in detail herein.
• The[0048]axle22 is fixedly mounted on the body of thetrailer26 by suitable means and is formed from a hollow tube (only one end of which is shown). The ends of thehollow axle22 have a thread form on the exterior surface thereof. The inner surface of each end of theaxle22 has aportion30 which has an increased inner diameter relative to an inner diameter of a central portion of theaxle22. Theaxle22 is formed from a suitable strong rigid material.
• The[0049]wheel hub assembly28 is mounted on the end of theaxle22 and generally surrounds theaxle22. Thewheel hub assembly28 includes awheel hub32, a plurality ofinner bearings34, a plurality ofouter bearings36, and ametal hub cap38. Thewheel hub32 is attached to the brake drum by suitable known means, such as bolts. Thewheel hub32 has aportion33 which is precisely machined in the end thereof.
• The inner and[0050]outer bearings34,36 are mounted between thewheel hub32 and theaxle22 by respective bearing cups40 and bearingcones42 and allow for rotation between the fixedaxle22 and the rotatingwheel hub assembly28 and air brake mechanism. Theouter bearings36 are mounted in theportion33 such that the bearing cups40 abut against a shoulder formed by theportion33. This precisely mounts theouter bearings36 on thewheel hub32 and therefore, relative to theaxle22. The inner andouter bearings34,36 are mounted at locations which are spaced apart from each other along the length of theaxle22 such that acavity44 is provided between thewheel hub32, theaxle22 and thebearings34,36. A bath of oil or semi-fluid synthetic grease is contained within thecavity44. Thebearings34,36 are lubricated by the bath of oil or semi-fluid synthetic grease contained therewithin.
• The[0051]hub cap38 surrounds the end of theaxle22 and prevents the oil or grease from leaking out of the end of thewheel hub assembly28. Thehub cap38 includes anouter end wall46, afirst side wall48, asecond side wall50, athird side wall52 and aninner end wall54. Thewalls46,48,50,52,54 are integrally formed with each other. Theouter end wall46 is circular. Thefirst side wall48 is generally perpendicular to theouter end wall46 and has a first end connected to theouter end wall46 and tapers from its first end to its second, larger end. Thesecond side wall50 has a first end connected to the second end of thefirst side wall48 and tapers from its first end to its second, larger end. Thethird side wall52 has a first end connected to the second end of thesecond side wall50 and tapers from its first end to its second, larger end. Theinner end wall54 is annular and is generally perpendicular to thethird side wall52 and has a first end connected thereto and extends outwardly therefrom. Theinner end wall54 is parallel to theouter end wall46. A plurality of apertures are provided through theinner end wall54 through which thehub cap38 is attached to the end of thewheel hub32 by suitable means, such asbolts56.
• The[0052]third side wall52 has anend portion55 which extends past theinner end wall54. When thehub cap38 is mounted on thewheel hub32, theend portion55 seats within theportion33 of thewheel hub32 and abuts against thecones40 of theouter bearings36. This locates thehub cap38 precisely on thewheel hub32 and on theaxle22.
• A washer[0053]58 is mounted on the threaded end of theaxle22 and bears against the bearingcones42 of theouter bearings36. An inner adjusting nut is60 threaded onto the threaded end of theaxle22 and bears against the washer58. The adjusting nut60 is locked onto theaxle22 by threading anouter jam nut62 on the threaded end of theaxle22. The adjusting nut60 is used for properly positioning the bearing cups42 of theouter bearings36. The washer58, the inner adjusting nut60 and theouter jam nut62 are proximate to thethird side wall52 of thehub cap38. The washer58, the inner adjusting nut60 and theouter jam nut62 do not completely fill the space between theaxle22 and thehub cap38 such that a space is formed therebetween. It is to be understood that other components can be threaded on the end of theaxle22 to position theouter bearings36.
• A[0054]freeze plug64 sits within and fills theend portion30 of theaxle22. The freeze plug64 has a circularcentral portion66 and anannular skirt68 which depends therefrom. Theskirt68 tightly engages with the inner surface of theend portion30 of theaxle22. Acentral aperture70 and a second aperture (not shown) therethrough which is offset from thecentral aperture70 are provided through thecentral portion66 of thefreeze plug64. A grommet (not shown) is provided within the second aperture. The freeze plug64 prevents oil or grease from entering into theaxle22 and prevents debris from going from within theaxle22 outwardly therefrom.
• The wheel speed and[0055]direction sensor20 includes asensor member72 and anexciting ring74. Thesensor member72 is mounted in the end of theaxle22 and is spaced from thefreeze plug64. Theexciting ring74 is mounted on thehub cap38 by a mountingwheel75.
• The[0056]sensor member72 includes aplastic body76 which extends partially into the end of theaxle22 and extends outwardly therefrom, and aplastic cover78 which covers the section of thebody76 which extends outwardly from the end of theaxle22. Thecover78 is suitably secured to thebody76. A recess is formed between thebody76 and thecover78. Acentral aperture80 is provided through thebody76 and thecover78 and aligns with thecentral aperture70 through thefreeze plug64. A plurality of L-shapedvents81 are provided through the periphery ofbody76 to provide an air passageway from the space between thefreeze plug64 and thebody76 and the space between thesensor member72 and thehub cap38.
• The[0057]body76 of thesensor member72 is fastened to theaxle22 by abolt82 which is mounted in thecentral aperture80 through thebody76. Thebolt82 threads with thecentral aperture70 through thefreeze plug64. The thread form in thefreeze plug64 may be pre-tapped or may be generated using a thread forming bolt.
• The[0058]central aperture80 in thebody76 allows for the possibility of an air passage through thebody76 if ahollow bolt82 is utilized as shown. This allows for the incorporation of a central tire inflation (CTI) in the present system. CTI systems automatically keep tires inflated by passing air from a compressed air reservoir mounted on thetrailer26 to the tires. One possible implementation of a CTI system with the present invention passes air through a tube in thehollow axle22, then through a swivel connection with a rotating seal to air fittings on the outside of thehub cap38. The air is then piped to the inflation valves for the tires. A suitably designedhollow bolt82 allows for the air to pass from the tube in thehollow axle22 to the rotating seal in thehub cap38. Thesensor member72 of the present invention allows for CTI but does not economically penalize the majority of applications where CTI is not used.
• To protect the[0059]bearings36,38, the entire axle end area is sealed from moisture, dirt and other contaminants. Suitable venting is provided so that the seals within thewheel mounting apparatus24 are not subjected to excessive pressure buildup. Depending on the wheel end construction, different methodologies may be used which use suitable vents in thehub cap38, seals and/or thefreeze plug64. Thesensor member72 of the present invention is compatible with all such approaches. Consequently, the periphery of the body includes the L-shapedventing slots81 such that pressure on both the front and back of thesensor member72 remains equalized. As for a conventional wheel end construction, venting and sealing are controlled by the hub cap, freeze plug and bearing seals. It should be noted that, depending on the application and the method of lubrication of the bearings, all parts of thesensor member72 may be subject to oil splash. The design and material of thesensor member72 of the present invention allows for operation in this environment.
• An[0060]electronic circuit assembly84 is provided between thebody76 and thecover78 of thesensor member72. Theelectronic circuit assembly84 includes a printedcircuit board86 mounted on thebody76 by suitable means such that the printedcircuit board86 is positioned between thebody76 and thecover78 of thesensor member72.Wires90 extend from the printedcircuit board86 through the grommet in thefreeze plug64, through thehollow axle22 to a current supplyingcontroller92. Thecontroller92 is preferably the ECM of the ABS or EBS of thetrailer26. If desired, a second controller can be provided.
• Wheel speed and[0061]direction sensing elements94,96 are provided on the printedcircuit board86 in the form of an application specific integrated circuit (ASIC)88. The preferred embodiment of the present invention uses “active” technology. The wheel speed anddirection sensing elements94,96 are preferably a pair of hall effect semiconductor elements. The halleffect semiconductor elements94,96 can be soldered to the printedcircuit board86 at the outermost end thereof and at spaced locations from each other. Preferably, however, the halleffect semiconductor elements94,96 are located on the same silicon chip. This aids in overall economy and, because of the use of standard integrated circuit fabrication techniques, relative location can be controlled. The face of each hall effectsemiconductor sensing element94,96 is parallel to the axis of rotation of theaxle22.
• The[0062]second side wall50 of thehub cap38 is machined to provide a recess in which the mountingwheel75 is located. To secure the mountingwheel75 to the inside of thesecond side wall50, the metalsecond side wall50 is deformed. This precisely locates the mountingwheel75 on thehub cap38. Because thehub cap38 is precisely mounted on thewheel hub32 andaxle22 as discussed herein, the mountingwheel75 is precisely mounted on thewheel hub32 andaxle22.
• The[0063]exciting ring74 is mounted on the inner surface of the mountingwheel75 and is proximate to, but spaced from the hall effectsemiconductor sensing elements94,96. Because the mountingwheel75 is precisely mounted on thewheel hub32 andaxle22, theexciting ring74 is precisely mounted on thewheel hub32 andaxle22. Theexciting ring74 and thesensor member20 are concentric with each other when mounted. As such, a defined radial gap is provided between theexciting ring74 and the hall effectsemiconductor sensing elements94,96. The hall effectsemiconductor sensing elements94,96 are mounted on the printedcircuit board86 so as to precisely line up with theexciting ring74 when thehub cap38 is mounted on thewheel hub32.
• Because the face of each hall effect[0064]semiconductor sensing element94,96 is parallel to the axis of rotation of theaxle22, a constant gap is maintained by thebearings36. Axial movement of thewheel hub32 does not have a significant effect and no gap adjustment is required. The gap is set by design, and gap variation is directly controlled by thebearings36. The gap is dependent on the concentricity of the mounting of theexciting ring74 within thehub cap38.
• In the preferred implementation, the[0065]exciting ring74 is a multi-pole magnet fabricated using ferrite in a plastic matrix material. Because theexciting ring74 is carried on the mountingwheel75 mounted inside thehub cap38, the magnet poles can be located precisely both circumferentially around thesensor member72 and radially relative to thesensor member72. This positioning eliminates many of the difficulties associated with the prior art stamped exciting ring. As such, the gap between theexciting ring74 and the hall effectsemiconductor sensing elements94,96 is radial so that the gap is directly controlled by the position of thebearings36 and is not influenced by axial movement of thewheel hub32. Alternatively, a stamped, toothed ring can be used as theexciting ring74.
• The hall effect[0066]semiconductor sensing elements94,96 are spaced apart from each by an integral number of pole pairs or teeth, depending on the type ofexciting ring74 that is used, plus or minus approximately ninety degrees.
• To allow for overall optimization of the[0067]sensor member72 and for ABS function or EBS function, when the present invention is used in an ABS or EBS as described herein, the preferred embodiment of theexciting ring74 does not conform to the present industry standard of one hundred teeth. Instead, the present invention uses twenty-five pole pairs in theexciting ring74. These pole pairs are precisely located so that with use of suitable electronic resolution enhancement techniques, an information rate equivalent to fifty pole pairs using standard techniques is achieved.
• FIG. 8 illustrates a circuit which implements this resolution enhancement technique. Signals A and B originate from the hall effect[0068]semiconductor sensing elements94,96. Signals A and B are input into anXOR gate118. The resulting waveform is generated as output C. Other suitable circuits can be used.
• The details of the implementation of the sensor electronics using an available[0069]integrated circuit120 is shown in FIG. 9. The circuit as shown in FIG. 9 includesintegrated circuit120,resistors122,124, andcapacitors126,128,130. A suitableintegrated circuit120 is an Allegro A3422LKA integrated circuit. The two halleffect semiconductor elements94,96 are embedded on one piece of silicon in theintegrated circuit120 such that the two halleffect semiconductor elements94,96 are spaced a suitable distance for quadrature implementation. The Vcc pin1 ofintegrated circuit120 is a voltage input. TheDIR pin2 ofintegrated circuit120 outputs direction information using high/low logic. TheGND pin3 ofintegrated circuit120 is connected to ground. TheSPD pin5 ofintegrated circuit120 outputs a frequency signal proportional to wheel speed. TheSPD pin5 ofintegrated circuit120 implements the resolution enhancement functionality described earlier and shown in FIG. 8.Resistor124 is connected to pin5. The EI pin4 ofintegrated circuit120 is connected to ground byresistor122.
• In operation, the[0070]wheel hub32, thehub cap38, the mountingwheel75 and theexciting ring74 rotate relative to the fixedaxle22 and thesensor member72 mounted thereon. Thecontroller92 supplies electric current to thesensor member72 which is a current sink. The hall effectsemiconductor sensing elements94,96 sense whether a north pole or a south pole of theexciting ring74 is present.
• If a multi-pole magnet is used as the[0071]exciting ring74, if a north pole is present, the hall effectsemiconductor sensing elements94,96 sink14 mamps, for example, from thecontroller92, and if a south pole is present, the hall effectsemiconductor sensing elements94,96sink 7 mamps, for example, from thecontroller92. This information is conveyed to another part of theASIC 88, to obtain a square wave as the poles are going by. Thecontroller92 determines how many times thesensor member72 switches between 14 mamps and 7 mamps. This change happens fifty times every revolution of the tire.
• If a toothed wheel is used as the[0072]exciting ring74 and a tooth is present, the hall effectsemiconductor sensing elements94,96 sink 14 mamps, for example, from thecontroller92. On the other hand, if a space is present, the hall effectsemiconductor sensing elements94,96sink 7 mamps, for example, from thecontroller92. This information is conveyed to another part of theASIC 88, to obtain a square wave as the poles are going by. Thecontroller92 determines how many times thesensor member72 switches between 14 mamps and 7 mamps. This change happens fifty times every revolution of the tire.
• The frequency of the change is proportional to the wheel speed. This information is used by the ABS or EBS to function in a like manner to how a conventional wheel speed sensor information is used to slow the[0073]trailer26, if necessary.
• The frequency output on the[0074]SPD pin5 ofintegrated circuit120 is implemented using high/low voltage levels. As implemented in the circuit shown in FIG. 9, this voltage signal is converted into a two level current signal by the presence ofresistor124.SPD pin5 pulls current throughresistor124 whenSPD pin5 is low. WhenSPD pin5 is high, current is not pulled throughresistor124. The interface electronics then senses the current variation. This keeps the overall wiring interface to three leads, power, ground and direction. Current pulses in the power lead correspond to the passage of poles as theexciting ring74 rotates or to the passage of teeth if a toothed ring is used. The E1 signal output on pin4 fromintegrated circuit120 from the integrated circuit is not required in this application and is held at ground byresistor122. Thecapacitors126,128,130 provide noise suppression.
• The integrated[0075]circuit120 does not output a current, such that a low is provided, onDIR pin2 when thetrailer26 is backing up. Thecontroller92, which is the ECM of the ABS or EBS, detects that theintegrated circuit120 is not outputting current and determines that thetrailer26 is backing up. This information is used by thecontroller92 of the ABS or EBS to activate the circuitry to perform the desired function or functions, such as sounding an audible back-up alarm and/or lighting a back-up lamp. Because the forward and reverse wheel speed information is available to thecontroller92, the information can be used to provide enhanced functionality over and above that of ABS or EBS without the forward and reverse wheel speed information.
• [0076]Auxiliary pin7 of the J560 connector can be used, for example, to power an audible back-up alarm and/or a back-up lamp. Thecontroller92 has an electrical switching element which provides power to the audible back-up alarm and the back-up lamp when thetrailer26 is moving in reverse. FIG. 10 shows an implementation of the overall system. Thecontroller92, in addition to being connected to theintegrated circuit120, is connected to pin7 of the J560 connector through avoltage regulator132. As such, when the ignition is turn on, power is supplied to pin7 and thus to thecontroller92. Thecontroller92 is also connected to aresistor134 which is connected to the base of atransistor136. The emitter of thetransistor136 is connected to ground. The collector of thetransistor136 is connected to an inductor of a coilinclusive relay138. The opposite side of the inductor of the coilinclusive relay138 is connected to thevoltage regulator132. Adiode140 is connected to both sides of the inductor of the coilinclusive relay138.Pin7 is connected to one side of the relay of the coilinclusive relay138. The other side of the relay of the coilinclusive relay138 provides 12V for the audible back-up alarm and the back-up lamp.
• In operation, the[0077]controller92 utilizes the direction input from theDIR pin2 of theintegrated circuit120 to turn on thetransistor136. The allows the current fromPin7 of the J560 connector to flow through thetransistor136, thereby closing the relay. Because the relay is closed, power flows through the relay fromPin7 of the J560 connector to provide power for the audible back-up alarm and back-up lamp, or for any other purposes.
• As noted earlier many tractors have power available on[0078]Pin7 of the auxiliary connector. In all cases, on new trailers,Pin7 is connected to the ECM of the ABS or EBS. It should also be noted that this power supply, under current mandated requirements, is not required to be dedicated solely to the ABS function or EBS function.
• In a preferred implementation, the power is not activated solely on the basis of whether the direction sensor gives an indication of reverse movement. The[0079]controller92, under stored program control, implements delays before switching on or off power. This avoids the irritation of flashing back-up lamps and ensures that the back-up lamps remain on when the driver stops briefly during a back-up maneuver. Such stops are very common, particularly when backing up tractor-trailer combinations. The light level is also sensed by a suitable sensor (not shown) mounted on thetrailer26 and in communication with thecontroller92 so that the back-up lamps do not illuminate if they are not required. These and other variations will be apparent to those skilled in the art.
• Individual active sensors are the preferred sensors for the present invention. The chips which implement the Hall effect function are small. Relative location can be tightly controlled by mounting on the same printed circuit board. The two hall[0080]effect semiconductor elements94,96 can be located on the same silicon chip. This aides overall economy and, because of the use of standard integrated circuit fabrication techniques, relative location becomes almost a non-issue. Two integrated circuits can be provided on the silicon chip, each having a hall effect element thereon.
• It is to be understood that conventional VR sensors can be used instead of hall effect[0081]semiconductor sensing elements94,96.
• While a preferred embodiment of the present invention is shown and described, it is envisioned that those skilled in the art may devise various modifications of the present invention without departing from the spirit and scope of the appended claims.[0082]

Claims (32)

The invention claimed is:

1. A braking and back-up warning system for a vehicle having at least one wheel, said system comprising:

a brake mechanism;

a pneumatic control module connected to said brake mechanism;

electronic structure configured to perform a back-up warning function;

an electronic control module connected to said pneumatic control module and to said electronic structure; and

a wheel sensing arrangement connected to said electronic control module, said wheel sensing arrangement configured to sense movement of the wheel of the vehicle and configured to communicate information relating to that which is sensed by said wheel sensing arrangement to said electronic control module, said electronic control module configured to operate said pneumatic control module based on information which is received from said wheel sensing arrangement relating to a speed of the wheel which is sensed by said wheel sensing arrangement, said electronic control module configured to operate said electronic structure based on information which is received from said wheel sensing arrangement relating to a direction of the wheel which is sensed by said wheel sensing arrangement.

2. A system as defined inclaim 1, said electronic structure comprising at least one of structure for sounding an audible alarm and a lamp.

3. A system as defined inclaim 1, said wheel sensing arrangement comprising a circuit which includes at least one sensor configured to sense movement of the wheel, said circuit configured to provide at least one signal to said electronic control module relating to the speed of the wheel which is sensed by the circuit and provide at least one signal to said electronic control module relating to the direction of the wheel which is sensed by the circuit.

4. A system as defined inclaim 3, wherein said circuit comprises an integrated circuit which includes at least one sensor configured to sense movement of the wheel.

5. A system as defined inclaim 1, further comprising a voltage source, said electronic control module comprising a relay and configured to selectively operate said relay to connect said voltage source to said electronic structure which is configured to perform said back-up warning function.

6. A system as defined inclaim 5, said electronic control module further comprising a controller which is configured to receive said information from said wheel sensing arrangement relating to the speed and direction of the wheel which is sensed by said wheel sensing arrangement.

7. A system as defined inclaim 6, said electronic control module further comprising a transistor connected to said controller, said controller configured to actuate said transistor based on said information which is received from said wheel sensing arrangement relating to the direction of the wheel which is sensed by said wheel sensing arrangement, said transistor connected to said relay and configured to close said relay upon being actuated by said controller.

8. A system as defined inclaim 5, wherein said voltage source is 12 volts provided by a J560 connector.

9. A system as defined inclaim 1, further comprising a voltage source, said electronic control module configured to selectively connect said voltage source to said electronic structure which is configured to perform said back-up warning function, depending on the information which is received from said wheel sensing arrangement relating to the direction of the wheel which is sensed by said wheel sensing arrangement.

10. A system as defined inclaim 9, wherein said voltage source is 12 volts provided by a J560 connector.

11. A braking and back-up warning system for a vehicle having at least one wheel, said system comprising:

a brake mechanism;

a pneumatic control module connected to said brake mechanism;

at least one of structure for sounding an audible alarm and a lamp;

an electronic control module connected to said pneumatic control module and to at least one of said structure for sounding an audible alarm and said lamp;

a voltage source connected to said electronic control module; and

a circuit which includes at least one sensor configured to sense movement of the wheel, said circuit configured to provide at least one signal to said electronic control module relating to the speed of the wheel which is sensed by said circuit and provide at least one signal to said electronic control module relating to the direction of the wheel which is sensed by said circuit, said electronic control module configured to operate said pneumatic control module based on said at least signal which is received from said circuit relating to a speed of the wheel which is sensed by said circuit, said electronic control module configured to selectively connect said voltage source to at least one of said structure for sounding an audible alarm and said lamp, depending on the at least one signal which is received from said circuit relating to the direction of the wheel which is sensed by said circuit.

12. A system as defined inclaim 11, wherein said circuit comprises an integrated circuit which includes at least one sensor configured to sense movement of the wheel.

13. A system as defined inclaim 11, said electronic control module comprises a relay and is configured to selectively operate said relay to connect said voltage source to at least of said structure for sounding an audible alarm and said lamp.

14. A system as defined inclaim 11, said electronic control module further comprising a controller which is configured to receive said at least one signal from said wheel sensing arrangement relating to the speed and direction of the wheel which is sensed by said circuit.

15. A system as defined inclaim 14, said electronic control module further comprising a transistor connected to said controller, said controller configured to actuate said transistor based on said at least one signal which is received from said circuit relating to the direction of the wheel which is sensed by said circuit, wherein said transistor is connected to said relay and is configured to close said relay upon being actuated by said controller.

16. A system for a vehicle comprising:

an axle;

a wheel mounting assembly surrounding said axle;

a wheel mounted on said wheel mounting assembly;

an exciting element mounted on said wheel mounting assembly;

a sensor member mounted on said axle, said sensor member having at least one sensing element mounted thereon for use in determining the speed of rotation of said wheel and for determining the direction of rotation of said wheel by sensing said exciting ring; and

a controller for processing information from said sensor member regarding the speed of said wheel and the direction said wheel is rotating;

circuit means for performing a function on the vehicle, said controller being capable of activating said circuit means.

17. A system as defined inclaim 16, wherein two sensing elements are provided on said sensor member and are spaced apart from each other a predetermined distance.

18. A system as defined inclaim 16, wherein said at least one sensing element sinks current from said controller, and wherein the frequency at which said at least one sensing element sinks current from said controller is proportional to the speed of said wheel.

19. A system as defined inclaim 16, wherein said exciting element includes a plurality of magnet poles.

20. A system as defined inclaim 19, wherein two sensing elements are provided on said sensor member and are spaced apart from each other by an integral number of poles plus or minus approximately 90 degrees.

21. A system as defined inclaim 16, wherein said circuit means includes a relay.

22. A system as defined inclaim 16, wherein said controller is part of an anti-lock brake system or an electro-pneumatic brake system for the vehicle.

23. A system as defined inclaim 16, wherein said controller includes a stored program which is capable of providing constant power to said circuit means to perform said function on said vehicle.

24. A system as defined inclaim 23, wherein said function is a lamp being lit on the vehicle and/or an alarm being sounded on the vehicle.

25. A system as defined inclaim 16, wherein said function is a lamp being lit on the vehicle and/or an alarm being sounded on the vehicle.

26. A system as defined inclaim 16, wherein said at least one sensing element uses active sensing technology.

27. A system as defined inclaim 26, wherein said at least one sensing element is a pair of hall effect semiconductor elements.

28. A system as defined inclaim 27, wherein said pair of hall effect semiconductor elements are provided on one integrated circuit chip.

29. A system as defined inclaim 27, wherein said exciting element is a ferrite magnet in a plastic carrier matrix.

30. A system as defined inclaim 16, wherein power is supplied to said controller through a J560 connector.

31. A method of performing a function on a vehicle, such as lighting a lamp and/or sounding an alarm, comprising the steps of:

sensing the direction of rotation of a wheel of said vehicle; and

activating the function on said vehicle when said vehicle is in reverse.

32. A method as defined inclaim 31, further including the step of sensing the speed of the wheel of said vehicle prior to activating the function on said vehicle when said vehicle is in reverse.

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