US20080095598A1 - Vehicle restraint with bi-directional sensor - Google Patents

Abstract

A vehicle restraint restricts the movement of a vehicle at a loading dock by engaging the vehicle's RIG (rear impact guard). The vehicle restraint includes a barrier carried by a vertically translatable track follower, the barrier being driven by a motor or some other type of power unit. A RIG sensor detects the RIG's horizontal position relative to the barrier and can periodically energize the motor to maintain the barrier in generally continuous contact with the RIG, even if the RIG moves horizontally away from the barrier. Detection of such horizontal movement of the RIG triggers the barrier to move accordingly to reduce a horizontal gap that may have formed between the RIG and the barrier.

Description

FIELD OF THE DISCLOSURE
• The present disclosure generally pertains to a vehicle restraint that engages a truck's rear impact guard (RIG) to help prevent the truck from inadvertently pulling away from a loading dock. More specifically, to a vehicle restraint that senses horizontal movement of the RIG and responds to the sensing by helping to ensure that the restraint is in an acceptable horizontal position relative to the RIG.
BACKGROUND
• When loading or unloading a truck parked at a loading dock, it is generally a safe practice to help restrain the truck from accidentally moving too far away from the dock. This is often accomplished by a vehicle restraint that engages what is referred to, in the industry, as a truck's ICC bar (Interstate Commerce Commission bar) or RIG (Rear Impact Guard). An ICC bar or RIG is a bar or beam that extends horizontally across the rear of a truck, below the truck bed. Its primary purpose is to help prevent an automobile from under-riding the truck in a rear-end collision. A RIG, however, also provides a convenient structure for a vehicle restraint to engage, thereby obstructing the bar's (and thus, the truck's) movement away from the dock. To release the truck, at least a portion of the restraint is lowered to a stored position below the bar, which also allows the next truck to back into the dock.
• There are at least two general types of RIG-engaging vehicle restraints. A first type of RIG-engaging vehicle restraint relies on the power of the truck backing into the dock as the impetus for operating the vehicle restraint. This type of vehicle restraint may use spring force for storing the restraint in a normally raised position. As a truck backs its RIG over the upwardly biased vehicle restraint, the RIG engages a ramp or some other type of mechanical actuator that forces the restraint down, underneath the RIG. When the truck's RIG is properly positioned over the restraint, a relatively small power unit can be actuated to raise a barrier portion of the restraint in front of the RIG. Examples of such truck-powered vehicle restraints that store in a normally raised position are disclosed in U.S. Pat. Nos. 6,190,109; 6,322,310; 5,882,167; 5,702,223 and 5,297,921, all of which are specifically incorporated by reference herein.
• In addition to utilizing the truck's power to operate the vehicle restraint, the spring of such restraints also enables upwardly biased restraints to follow the incidental vertical movement of the RIG as the truck is being loaded or unloaded of its cargo. This can be advantageous in comparison to other types of vehicle restraints.
• A second general type of vehicle restraint stores in a lowered position and typically requires some type of power unit, such as a motor or hydraulic cylinder, to raise the restraint to an elevation where it can capture the RIG. Since the power unit must raise the entire moving portion of the vehicle restraint, lifting such weight may require a power unit of substantial size and horsepower, which can add even more weight to the restraint. The power unit of this vertically moving restraint may include a small spring, or other mechanism, to accommodate slight vertical movement of the truck/RIG, but a vehicle restraint of this type typically has no mechanism for accommodating horizontal movement of the RIG.
• A limitation common to both types of restraint is an inability of the restraint to follow the horizontal movement of the RIG. For example, after a vehicle restraint is initially positioned relative to the RIG, the loading or unloading operation may cause the truck to move both vertically and horizontally. The vehicle restraint's barrier prevents the RIG from moving forward horizontally, in a direction opposite the dock face, but it does not generally accommodate the RIG moving backward in a horizontal direction toward the dock face (away from the restraint's raised barrier). This can leave a horizontal gap between the RIG and the barrier even though the spring or actuator allows for vertical movement and continues to hold the restraint tightly up against the underside of the RIG. If the vehicle later begins to return to its more forward position, the gap provides a backlash in which the RIG can accelerate before striking the barrier with an impact that may be sufficient to bend or otherwise damage the RIG. In the case of a premature truck/trailer departure, this horizontal gap may actually allow a trailer to build up enough momentum to “jump” over the barrier prior to the operator lowering the restraint and releasing the trailer.
• Known prior art restraints included no means for detecting the horizontal position of the RIG relative to the vehicle restraint's barrier. Because the RIG's horizontal position relative to the barrier was not detected, prior art restraints did nothing to eliminate the potentially hazardous horizontal gap that may result from the backward movement of the trailer (and RIG), nor did they do anything to alert workers of such a hazardous condition. Consequently, a need exists for a vehicle restraint that can properly respond not only to vertical movement of a RIG but also to horizontal movement of a RIG to warn of, and preferably minimize, a gap that may form between the barrier and the RIG upon horizontal movement of the RIG.
SUMMARY
• In order to provide a vehicle restraint that can properly respond to horizontal movement of a RIG, a restraint disclosed herein includes a sensor that detects whether a RIG has moved horizontally away from the restraint's barrier.
• In some examples, the vehicle restraint includes a barrier that can rotate to take up both horizontal and vertical slack between the barrier and a RIG.
• In some examples, the vehicle restraint includes a dual-plate barrier with a RIG sensor protectively interposed between the two plates.
• In some examples, the RIG sensor includes an optical device.
• In some examples, the RIG sensor includes a pivotal arm.
• In some examples, a spring moves the vehicle restraint in response to vertical movement of the RIG, and a motor moves the restraint's barrier in response to horizontal movement of the RIG.
• In some examples, a spring biases the vehicle restraint upward, and a motor rotates the restraint's barrier between a protruding blocking position and a retracted stored position.
• In some examples, the vehicle restraint is a vertically moving restraint that includes a sensor to detect whether a RIG has moved horizontally away from a barrier included on the restraint.
• In some examples, the vertically moving restraint responds to the sensor detecting that the RIG has moved horizontally away from a barrier by triggering a signaling system.
• In some examples, the vertically moving restraint responds to the sensor detecting that the RIG has moved horizontally away from a barrier by moving the barrier horizontally toward the RIG.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a right side view of a vehicle restraint with its track follower raised and its barrier in a stored position.
• FIG. 2 is a right side view of the vehicle restraint ofFIG. 1 but showing a vehicle lowering the track follower.
• FIG. 3 is a right side view of the vehicle restraint ofFIG. 1 but showing the vehicle's RIG on top of the track follower.
• FIG. 4 is a right side view similar toFIG. 3 but showing the barrier at its blocking position.
• FIG. 5 is a right side view similar toFIG. 4 but showing the RIG having moved away from the barrier.
• FIG. 6 is a right side view similar toFIG. 5 but showing the vehicle restraint's response to the RIG's horizontal movement away from the barrier.
• FIG. 7 is a front view ofFIG. 1 but with a ramp extension omitted to show other features of the restraint more clearly.
• FIG. 8 is a right side view similar toFIG. 3 but illustrating an alternate example.
• FIG. 9 is a right side view showing another operating position of the vehicle restraint ofFIG. 8.
• FIG. 10 is a right side view showing another operating position of the vehicle restraint ofFIG. 8.
• FIG. 11 is a right side view showing another operating position of the vehicle restraint ofFIG. 8.
• FIG. 12 is a right side view showing another operating position of the vehicle restraint ofFIG. 8.
• FIG. 13 is a right side view showing another operating position of the vehicle restraint ofFIG. 8.
• FIG. 14 is a right side view similar toFIG. 3 but illustrating yet another example.
• FIG. 15 is a right side view showing another operating position of the vehicle restraint ofFIG. 14.
• FIG. 16 is a right side view of a vertically moving vehicle restraint with its track follower lowered and its barrier assembly in a stored position.
• FIG. 17 is a right side view of the vehicle restraint ofFIG. 16 but showing the vehicle's RIG engaged by the barrier assembly, wherein the barrier assembly is in its blocking position.
• FIG. 18 is similar toFIG. 17, but shows an enlarged view of the barrier assembly in its blocking position.
• FIG. 19 is similar toFIG. 18, but shows another mechanism for horizontally positioning the barrier.
DETAILED DESCRIPTION
• To help prevent a vehicle10 (e.g., truck, trailer, etc.) from accidentally pulling too far away from adock face12 of aloading dock14, avehicle restraint16 includes abarrier18 for engaging or capturing aRIG20, or ICC bar, ofvehicle10 as the vehicle is being loaded or unloaded of its cargo. Becausevehicle10 typically has some incidental movement during loading and unloading operations,vehicle restraint16 includes aRIG sensor22 and other structure that enablesrestraint16 to properly respond to such movement.FIGS. 1-6 are right side views illustrating the operating sequence ofvehicle restraint16, andFIG. 7 is a front view ofFIG. 1 (looking toward dock face12). Aramp extension24 is omitted inFIG. 7 to show other features ofrestraint16 more clearly.
• To vertically positionvehicle restraint16 relative to RIG20,restraint16 comprises atrack follower26 that is movable between a raised position (FIGS. 1 and 7) and various lowered positions (FIGS. 2-6). The vertical movement oftrack follower26 is guided by atrack28 that can be mounted to dockface12. Atension spring30, or some other type of resilient member, biases trackfollower18 to its raised position (FIGS. 1 and 7), thus urgingtrack follower26 up against the underside ofRIG20 whenRIG20 is positioned abovetrack follower26 as shown inFIGS. 3-6.
• In order to captureRIG20 and thus limit its movement away fromdock face12,track follower26 carriesrotatable barrier18 that a powered drive unit32 (e.g., an electric motor, hydraulic motor, piston/cylinder, etc.—seeFIG. 7) can rotate between a stored position (FIGS. 1,2,3 and7) and various blocking positions (FIGS. 4,5 and6).
• Although the actual operation ofvehicle restraint16 may vary,FIGS. 1-6 illustrate an example. Operation may begin as shown inFIG. 1, wherevehicle10 is backing intodock14 whiletrack follower26 is at its raised position, andbarrier18 is at its stored position.
• InFIG. 2,vehicle10 continues backing intodock14, which forcesRIG20 to slide over aramp34 or to engage some other type of mechanical structure that enablesvehicle10 to forcetrack follower26 down underneathRIG20. In this example, the interaction betweenramp34 andRIG20 forces trackfollower26 downward against the upward urging ofspring30.
• InFIG. 3,vehicle10 is shown having backedRIG20 overtrack follower26 such thatRIG20 passes over the top of adistal end36 ofbarrier18.RIG20 is now in a position wherebarrier18 can rise to captureRIG20.
• InFIG. 4, power unit32 (FIG. 7) rotatesbarrier18 from its stored position to a blocking position to help containRIG20 at a location that ensures a certain amount oflip purchase42 or overlap between alip38 of aconventional dock leveler40 and arear edge44 ofvehicle10. Oncebarrier18 rises to its blocking position,dock leveler40 can be operated in a conventional manner to setlip38 upon the vehicle's truck bed as shown inFIG. 4.
• Although the initial energizing ofpower unit32 to raisebarrier18 could be done automatically in response to some type of sensor that senses the arrival ofvehicle10 orRIG20, in some cases the initial energizing ofpower unit32 is simply triggered by a conventional manually operated switch. Once energized,power unit32 continues raisingbarrier18 untilRIG sensor22 determines thatRIG20 is within a RIG-receivingthroat area44, or preferred capture area, ofbarrier18. OnceRIG sensor22 determines thatRIG20 is within the RIG-receivingthroat area22, or preferred capture area,power unit32 is de-energized, thereby stopping upward movement ofbarrier18.RIG sensor22 may also be electrically coupled with a signaling system (e.g., visual or audible communication means) to alert interested parties of the position of the barrier relative to the RIG. This arrangement may offer some advantages over prior art rotating hook restraints.
• Prior art rotating hook restraints typically included a timer that was started at the same time the power unit was triggered. The power unit was then energized for a pre-determined period of time, after which the timer cut power to the power unit. The timer's period of time was set as the period of time necessary to ensure that the hook would rotate enough to properly capture the highest RIG in a given service range. If the RIG was lower in elevation, though, the hook would engage the RIG before the timer expired. Because the timer had not expired, the power unit would continue to be energized, even though the hook could not move any further (contact with the RIG prevented further movement). This arrangement required the use of a slip clutch to prevent damage to the system components during the period of time in which the power unit continued to be energized although the hook could move no further. Because this type of rotating hook restraint did not rely on the position of the RIG relative to the restraint, proper RIG-restraint engagement was indirectly measured by detecting the rotational position of the restraint hook. For example, U.S. Pat. No. 4,267,748 discloses a finger or cam attached to the shaft of the rotating hook. When the shaft was rotated, raising the hook to an operational position, the finger or cam would engage a switch, thereby indicating that the hook was in its operational position. As described, this type of system only detects the rotational position of the restraint hook, not the hook's actual position relative to the RIG. Accordingly, prior to the current invention, a rotating hook vehicle restraint's actual engagement with the RIG was not directly sensed or indicated.
• By sensing the actual presence of the rotating hook in a preferred capture area, the current restraint may reduce wear on the power unit, and it may eliminate the need for a timer and a slip clutch, along with other benefits. Although the actual design ofRIG sensor22 may vary, the sensor will provide the aforementioned benefits. In some examples,RIG sensor22 comprises asensing arm46 pivotally coupled tobarrier18 by way of ashaft48 or some other pivotal connection.RIG sensor22 may further comprise aspring50, amechanical stop52, and a limit switch54 (proximity switch, electromechanical switch, etc.). In this example ofRIG sensor22,arm46 can pivot betweenmechanical stop52 andswitch54, whilespring50biases arm46 towardstop52.Switch54 provides a make or break signal56 (FIG. 7) whose on/off states are determined by whetherarm46 isadjacent switch54.
• InFIG. 3,arm46 is up againststop52, so signal56 allowspower unit32 to be energized via the manually operated switch mentioned earlier. Once energized,barrier18 continues to rise until the engagement betweenarm46 andRIG20forces arm46 to triggerswitch54. This causesswitch54 to change state such thatsignal56 now de-energizespower unit32 to stopbarrier18 at its blocking position ofFIG. 4. Accordingly, by detecting the actual position of the RIG relative to the barrier, the current restraint may reduce wear on the power unit (it does not run when the hook is in contact with the RIG) and may eliminate the need for a timer and a slip clutch.
• Withbarrier18 restrainingRIG20 andlip38 safely resting upon the vehicle's truck bed, as shown inFIG. 4,vehicle10 can now be safely loaded or unloaded of its cargo usingdock leveler40 as a bridge for personnel and material handling equipment to travel to and fromvehicle10.Switch54 and signal56 can also be electrically coupled to a signaling system, such as lights or audible alarms. For example, engagement betweenarm46 andRIG20forces arm46 to triggerswitch54, thereby causing it to change state such thatsignal56 changes a light inside the loading dock from red to green, indicating that the vehicle can now be safely loaded or unloaded. By measuring the actual position of the restraint relative to the RIG, a “false lock” indication, based only on the rotational position of the restraint, can be effectively avoided. Although a lighting system may be the most common means of communicating a proper position of the restraint relative to the RIG to dock workers, other forms of communication, or signaling, could readily be incorporated into the system.
• After the restraint is properly positioned relative to the RIG, the vehicle may be safely loaded or unloaded. As cargo or the weight of material handling equipment is added or removed from the vehicle's truck bed, the vehicle's suspension may allowvehicle10 to rise and descend accordingly.Track follower26 can readily follow such vertical movement and stay in contact with the underside ofRIG20 by virtue ofspring30, which urgestrack follower26 upward.
• In the position shown inFIG. 4,distal end36 ofbarrier18 is ahorizontal distance58 fromtrack28. According to an advantageous feature of this design, the length ofdistance58 may vary.Vehicle10, for instance, could subsequently move horizontally away from its position shown inFIG. 4 to its position shown inFIG. 5 whereRIG20 is up against adock bumper60. To eliminate the horizontal gap betweenbarrier18 andRIG20, the depicted restraint can sense the gap and re-positionbarrier18 to eliminate it. In this example, the horizontal movement would allowarm46 to return to its position againststop52, wherebysignal56 would re-energizepower unit32 to once again rotatebarrier18 towardRIG20.Barrier18 would continue rotating untilRIG20forces arm46 away fromstop52 tore-trigger switch54, wherebysignal56 would then stopbarrier18 at its newly adjusted blocking position ofFIG. 6.Horizontal distance58′ ofFIG. 6 is less thandistance58 ofFIG. 5, soRIG20 is more constrained inFIG. 6 than inFIG. 5. Reducing or eliminating the horizontal backlash ofRIG20 withinrestraint16 may reduce the possibility ofRIG20 hammering againstbarrier18 in an early departure situation. Thus, the barrier system according to one example provides sensing based on the actual presence of a RIG relative to the barrier, as opposed to sensing based on the rotational position of the hook. Put slightly differently, the barrier system disclosed herein detects the presence of the RIG in a preferred capture area, wherein the preferred capture area is an area in which the barrier is horizontally adjacent the RIG. In the case of a rotating hook restraint, the preferred capture area may also be referred to in the art as a RIG-receiving throat area. Furthermore, sensing that the RIG is not in the preferred capture area may also cause corrective action and/or signaling.
• Automatically repositioning the barrier in response to detecting that the RIG has moved horizontally away from the barrier offers numerous benefits, but it may not be desirable in all circumstances. For example, if the restraint rarely loses contact with the RIG, then it may be sufficient to sound an alarm or otherwise signal the loss of contact, wherein this alarm or signal alerts an operator that he must take action (e.g., push a button) to move the restraint horizontally toward the RIG. In this manner, the restraint system detects that the RIG has moved away from the barrier and triggers an alarm to alert a dock worker of a potentially unsafe condition that he should take steps to remedy.
• Although these functions could be accomplished by various structures,FIGS. 1-7 illustrate one example. In the illustrated example,track follower26 comprises twoside plates26aand26battached to abase62.Rollers64 or slide members extending fromside plates26aand26band protruding into two vertical channels oftrack28 help guide the vertical movement oftrack follower26. To urgetrack follower26 upward, one ormore springs30 extend betweenbase62 and anupper anchor66 affixed to track28. Althoughbarrier18 could be a single hook-shaped member,barrier18 comprises twoplates18aand18bthat help protectRIG sensor22 therebetween.Plates18aand18bcan be keyed toshaft48 to provide a positive drive connection to driveunit32. Achain68 and twosprockets70 and72 can couple the output ofdrive unit32 toshaft48. For overload protection, a slip clutch74 can be installed somewhere in the drive train betweenshaft48 and driveunit32, although the current sensing configuration may allow the slip clutch to be eliminated. Oneend74 ofspring50 can be attached to plate18b,and anopposite end76 can be attached toarm46.Stop52 can be a pin or some other suitable structure extending frombarrier18. At least part ofRIG sensor22 can be attached at an appropriate location onbarrier18.Restraint16 also may include abarrier sensor78 coupled to trackfollower26.Barrier sensor78 provides a stored-signal80 (FIG. 7) that triggerspowered drive unit32 to stop loweringbarrier18 when the barrier reaches its stored position.
• In the example ofFIGS. 1-7,barrier18 is keyed or otherwise solidly fixed toshaft48 whilearm46 can rotate aboutshaft48. In an alternate example, however, generally the opposite is true. More specifically,FIGS. 8-13 show avehicle restraint82 whosebarrier84 can rotate relative to ashaft86, but anarm88 is rigidly fixed toshaft86. Atension spring90, which extends betweenarm88 andbarrier84, urgesbarrier84 upward relative toarm88. In this case,spring90 is sufficiently strong to support the barrier's weight. The operation ofvehicle restraint82 may be as follows:
• FIG. 8 corresponds toFIG. 3.Vehicle10 just placed itsRIG20 uponvehicle restraint82.Barrier84 is at its stored position, andarm88 is resting upon stop member91. The tension inspring90 holdsbarrier84 slightly abovearm88.
• InFIG. 9, drive unit32 (FIG. 7) is raisingarm88 viashaft86, andbarrier84 rises witharm88 due tospring90.
• InFIG. 10,barrier84 makes initial contact withRIG20; however, drive unit32 (FIG. 7) continues raisingarm88 becausearm88 has not yet trippedswitch54.
• FIG. 11 showsarm88 having trippedswitch54, which de-energizes power unit32 (FIG. 7). The tripping ofswitch54 indicates thatRIG20 is in the preferred capture area, that is, properly positioned relative tobarrier84. Tripping ofswitch54 may also trigger an associated signaling system (lights, sound, or other) to communicate that the RIG is in the preferred capture area and the loading or unloading operation may commence. At thispoint vehicle restraint82 remains substantially stationary as long asRIG20 remains still. In this situation, the tension inspring90causes barrier84 to maintain some spring loaded-pressure againstRIG20. To preventRIG20 from forcingbarrier84 down past the elevation ofarm88,barrier84 includes astop block55 that limits the relative rotation betweenbarrier84 andarm88.
• IfRIG20 moves slightly closer to dockface12, as shown inFIG. 12,barrier84 will tend to follow that movement due to the urging ofspring90. If the movement ofRIG20 and the relative movement ofarm88 are small, such thatRIG20 remains in the preferred capture area, thenbarrier84 may be able to follow the RIG's movement withoutdrive unit32 having to be re-energized byswitch54. If, however, the movement ofRIG20 and the relative movement ofarm88 are sufficient to tripswitch54, indicating that a horizontal gap has developed betweenbarrier84 and RIG20 (i.e.,RIG20 has moved out of the preferred capture area), then driveunit32 is re-energized byswitch54 to forcearm88 andbarrier84 back up against the RIG, in its new position, as shown inFIG. 13. Thus,vehicle restraint82 can closely follow incidental movement ofRIG20 by spring force alone and follow greater movement by automatically energizingpower unit32 when a horizontal gap forms betweenbarrier84 andRIG20 such thatRIG20 moves out of the preferred capture area. With this design,drive unit32 could be energized less often. Also,arm88 never needs to actually contactRIG20, soarm88 could be completely hidden inside or underneathbarrier84. Furthermore, because the position of the restraint relative to the RIG is actually measured, the signaling system (lights or other) can be more accurate, allowing the system to more effectively alert dock workers of a potentially unsafe condition.
• FIGS. 14 and 15 illustrate yet another example of avehicle restraint92 that issimilar vehicle restraint16 ofFIGS. 1-7, whereinFIGS. 14 and 15 correspond toFIGS. 3 and 4 respectively. Withvehicle restraint92,RIG sensor22 is replaced by anoptical beam94 or comparable electromagnetic field emitted and/or received by afield type sensor96 mounted to abarrier98. Abeam reflector100 may or may not be needed depending on the chosen style ofsensor96. Withvehicle restraint92, the presence ofRIG20 in the preferred capture area can be detected byRIG20 interruptingbeam94 rather than by displacingarm46.
• Yet another example of avehicle restraint102 is shown inFIGS. 16-18. Like the previous examples,vehicle restraint102 is intended to help prevent a vehicle10 (e.g., truck, trailer, etc.) from accidentally pulling too far away from adock face12 of aloading dock14. As in the previous examples, the actual position of the RIG relative to the vehicle restraint's barrier is sensed, with the barrier position being altered, if the barrier moves out of the preferred capture area, to bring the barrier back into a proper position relative to the RIG. However, unlike the previous examples,vehicle restraint102, as shown inFIGS. 16-18, does not rely on an upwardly-biased, rotating hook vehicle restraint to provide a barrier to vehicle movement, instead relying on a vertically-movingbarrier assembly104.Barrier assembly104 comprises abarrier114, a slidingbarrier116, aRIG sensor118, aRIG sensor extension122, and aRIG sensor switch124.FIGS. 16-18 are right side views illustrating the operating sequence ofvehicle restraint102.
• FIG. 16shows barrier assembly104 in a stored position, wherein the barrier assembly is protected byhousing106. Barrierassembly position sensor108 is also protected byhousing106 and senses whenbarrier assembly104 is in its stored position. Aftervehicle10 is backed into a loading/unloading position againstloading dock bumper60, as shown inFIG. 17, the vehicle restraint may be actuated, energizing liftingcylinder110 and causing it to extend. As liftingcylinder110 extends, it exerts a force againstbarrier assembly104 causingrollers112 to travel upward withinroller track134, which can be mounted to dockface12.Barrier assembly104 can be attached torollers112 such thatbarrier assembly104 moves withrollers112.Barrier assembly104 continues to travel upward untilbarrier114contacts RIG20. Contact withRIG20 preventsbarrier assembly104 from moving any further upward, thereby causing the pressure in liftingcylinder110 to rise. Once the internal pressure of liftingcylinder110 reaches a pre-determined threshold, a second cylinder, slidingcylinder120, is energized. Once energized, slidingcylinder120 retracts, causing slidingbarrier116 to move horizontally towarddock face12. Slidingbarrier116 moves horizontally towarddock face12 untilRIG sensor118contacts RIG20.RIG sensor118 is pivotally mounted to slidingbarrier116 and biased to the rest position shown inFIG. 16, such that continued horizontal movement of sliding barrier towarddock face12causes RIG sensor118 to rotate untilRIG sensor extension122 actuatesRIG sensor switch124. RIG sensor switch can be a magnetic proximity switch, a physical contact switch, or one of a variety of other switches known and used by those of ordinary skill in the art. Actuation ofRIG sensor switch124 indicates that the RIG is in a preferred capture area, wherein preferred capture area refers to a position in which the RIG is horizontally adjacent the barrier. WhenRIG sensor switch124 detects that the RIG is in a preferred capture area, it causes both slidingcylinder120 and liftingcylinder110 to cease extending, resulting in the barrier assembly in the engaged position shown inFIGS. 17 and 18. Furthermore,RIG sensor switch124 may also be electrically coupled to a signaling system (lights, sound, or other) to accurately communicate information about the position of the restraint relative to the RIG to interested parties.
• As shown best inFIGS. 17 and 18, slidingbarrier116 includes anextension tip126 that extends over the top of a portion of the RIG. Like the rotating hook restraint shown inFIGS. 1-15, but unlike a traditional vertically-moving barrier,extension tip126 provides a barrier to upward movement of the RIG. Thus, in the event that the trailer's landing gear collapses,extension tip116 will help prevent the RIG (and the rear of the trailer) from rapidly moving upward. As detailed above,RIG sensor118 acts to ensure thatRIG20 is consistently positioned relative to slidingbarrier116 and extension tip126 (withRIG20 in the preferred capture area), such thatextension tip126 extends over a portion ofRIG20.
• As a fork truck enters and exits the trailer during the loading/unloading operation, the trailer (and the RIG) tends to move vertically, movement that is often referred to as trailer “float.” To allowbarrier assembly104 to followRIG20 as it floats slightly, thelower end130 of liftingcylinder110 is slidably mounted and attached to floatspring128. IfRIG20 moves slightly downward,float spring128 allowsbarrier assembly104 to follow such movement, and ifRIG20 moves back upward to its original position,float spring128 urgesbarrier114 upward, in contact withRIG20. Thus, if the RIG moves a relatively small amount,barrier assembly104 may be able to follow the RIG's movement without the need for liftingcylinder110 to be re-energized.
• However, vertical movement of the RIG is typically accompanied by horizontal movement of the RIG. IfRIG20 moves horizontally closer to dockface112, then a horizontal gap would result between the barrier andRIG20, such thatRIG20 may no longer be in the preferred capture area. According to an advantageous feature of this design, this gap may be sensed and minimized or eliminated. That is, for such horizontal RIG movement,RIG20 may lose contact withRIG sensor118, resulting inRIG sensor118 returning to its rest position andRIG sensor extension122 losing contact (e.g., magnetic contact or physical contact) withRIG sensor switch124. When engagement betweenRIG sensor extension122 andRIG sensor switch124 is lost (indicating that the RIG is no longer in the preferred capture area), liftingcylinder110 is re-energized and, once its internal pressure reaches the pre-determined level (as detailed above), slidingcylinder120 is re-energized. Re-energizing slidingcylinder120 causes it to retract, which, in turn, causes slidingbarrier116 to move horizontally towarddock face12 to minimize the horizontal gap that has formed betweenRIG20 and slidingbarrier116. Sliding barrier continues to move horizontally untilRIG sensor118contacts RIG20 andRIG sensor extension122 is re-engaged withRIG sensor switch124.Barrier assembly104 is thereby returned to its engaged position, whereinRIG20 is in the preferred capture area. Thus,RIG sensor118 helps ensure thatRIG20 is consistently and properly positioned relative to slidingbarrier116 and extension tip126 (i.e., in the preferred capture area). Furthermore,RIG sensor118 can be electrically coupled to a means for accurately signaling (via lights, sound, or other) when the RIG is properly positioned relative to the barrier assembly. If lights are used to signal, these lights may change state (e.g., change illuminated color, temporarily flash) until the RIG returns to the preferred capture area. Alternatively, a horn could sound in response toRIG sensor118 losing contact with the RIG. In fact, if the restraint rarely loses contact with the RIG, then it may be sufficient to sound an alarm or otherwise signal the loss of contact, wherein this alarm or signal alerts an operator that he must take action (e.g., push a button) to move the restraint horizontally toward the RIG.
• As described, when the RIG is properly positioned relative to the barrier assembly, float is accommodated viafloat spring128, pullout protection is provided viabarrier114, and vertical movement of the trailer and RIG is prevented byextension tip126.
• This arrangement may offer advantages over prior art vertically-moving restraints because it detects the horizontal position of the RIG relative to the barrier and adjusts the position of the barrier, if necessary, to help ensure a consistent horizontal relationship between the two (i.e., that the RIG is in a preferred capture area, such that any horizontal gap between the RIG and the barrier is minimized). Known prior art vertically-moving restraints only detect the vertical position of a RIG relative to the restraint (e.g., through use of a treadle plate mounted on an upper surface of the restraint). Prior to the current disclosure, known vertically moving restraints provided no means for addressing the problems associated with horizontal movement of the trailer (and RIG).
• FIG. 19 shows an example that is similar to that shown inFIGS. 16-18, but in this version, slidingcylinder120 has been replaced bycompression spring132. As in the previous examples, when the vehicle restraint is actuated, liftingcylinder110 is energized, causing it to extend. As liftingcylinder110 extends, it exerts a force that has both a horizontal and a vertical component. The vertical force component is exerted againstbarrier assembly104, whereas the horizontal force component is exerted againstspring132.Spring132 has a spring constant that is sufficient to temporarily resist the horizontal force component exerted by liftingcylinder110, thereby allowing the vertical force component exerted onbarrier assembly104 to causerollers112 to travel upward withinroller track134.Barrier assembly104 can be attached torollers112 such thatbarrier assembly104 moves withrollers112, as in previous examples.Barrier assembly104 continues to travel upward untilbarrier114contacts RIG20. Contact withRIG20 resists the vertical force component exerted by liftingcylinder110 and preventsbarrier assembly104 from moving any further upward, thereby causing the pressure in liftingcylinder110 to rise and the horizontal force component to increase. Eventually, the horizontal force component exerted by liftingcylinder110 reaches a level that can no longer be resisted byspring132 andspring132 is compressed. Asspring132 is compressed, slidingbarrier116 moves horizontally towarddock face12 untilRIG sensor118contacts RIG20.RIG sensor118 is pivotally mounted to slidingbarrier116 and biased to the rest position shown inFIG. 16, such that continued horizontal movement of sliding barrier towarddock face12causes RIG sensor118 to rotate untilRIG sensor extension122 actuatesRIG sensor switch124. Actuation ofRIG sensor switch124causes lifting cylinder110 to cease extending, resulting in the barrier assembly in its engaged position as shown inFIG. 19. As in the example ofFIGS. 16-18,RIG sensor118 helps ensure thatRIG20 is consistently and properly positioned relative to slidingbarrier116 and extension tip126 (i.e.,RIG20 is in the preferred capture area, such thatextension tip126 extends over the top of at least a portion of the RIG). Furthermore, when the RIG is properly positioned relative to the barrier assembly, float is accommodated viafloat spring128, pullout protection is provided viabarrier114, and vertical movement of the trailer and RIG is prevented byextension tip126.
• Although the invention is described with reference to various examples, it should be appreciated by those of ordinary skill in the art that various modifications are well within the scope of the invention. Various cover panels, for instance, can be added tovehicle restraints16,82 and92 to provide a neater appearance, enclose electrical connections, shelter working components from debris, and to cover potential pinch points. Therefore, the scope of the invention is to be determined by reference to the following claims:

Claims (30)

1. A method of operating a vehicle restraint disposed adjacent to a loading dock face, wherein the vehicle restraint includes a movable barrier adapted to prevent movement of a RIG (rear impact guard) of a vehicle in a direction opposite the loading dock face, wherein the RIG includes a front surface and a rear surface, the rear surface being closer to the loading dock face than the front surface, the method comprising:

moving the barrier to a first operative position wherein the barrier is horizontally adjacent the front surface of the RIG;

holding the barrier substantially stationary in the first operative position; and

sensing that the front surface is no longer horizontally adjacent the barrier.

2. The method ofclaim 1, further comprising moving the barrier at least horizontally toward the dock face to a second operative position, wherein the barrier is again horizontally adjacent the front surface, in response to sensing that the front surface is no longer horizontally adjacent the barrier.

3. The method ofclaim 1, further comprising illuminating a light in response to sensing that the front surface is no longer horizontally adjacent the barrier.

4. The method ofclaim 1, further comprising sounding an audible alarm in response to sensing that the front surface is no longer horizontally adjacent the barrier.

5. The method ofclaim 1, wherein moving the barrier to the first operative position comprises moving the barrier in an upward direction and in a horizontal direction toward the loading dock face.

6. The method ofclaim 1, wherein moving the barrier to the first operative position comprises rotating the barrier.

7. A method of operating a vehicle restraint disposed adjacent to a loading dock face, wherein the vehicle restraint includes a rotatable barrier with a distal end, and the rotatable barrier can be used for restricting a RIG (rear impact guard) of a vehicle, the method comprising:

raising the distal end after the RIG has passed thereover;

after raising the distal end, holding the distal end substantially stationary relative to the RIG; and

sensing horizontal movement of the RIG away from the distal end.

8. The method ofclaim 7, further comprising moving the distal end vertically and horizontally in response to sensing horizontal movement of the RIG.

9. The method ofclaim 7, wherein the raising of the distal end after the RIG has passed thereover is carried out by motorized rotation of the rotatable barrier.

10. The method ofclaim 7, further comprising illuminating a light in response to sensing horizontal movement of the RIG.

11. The method ofclaim 7, further comprising sounding an audible alarm in response to sensing horizontal movement of the RIG.

12. A vehicle restraint mountable near a loading dock for engaging a RIG (rear impact guard) of a vehicle, the vehicle restraint comprising:

a barrier that is movable relative to the loading dock;

a powered drive unit coupled to the barrier such that the powered drive unit can move the barrier; and

a RIG sensor coupled to the barrier and providing a signal in response to the RIG's horizontal position relative to the barrier, such that the powered drive unit moves the barrier toward the RIG until it receives the signal from the RIG sensor indicating that the barrier is horizontally adjacent the RIG, upon receiving the signal, the powered drive unit is de-energized, and after the powered drive unit is de-energized, the signal triggers the powered drive unit to be re-energized to further move the barrier toward the RIG to minimize a gap between the barrier and the RIG.

13. The vehicle restraint ofclaim 12, wherein the barrier comprises a rotating hook.

14. The vehicle restraint ofclaim 12, wherein the barrier comprises a vertically elongate member.

15. The vehicle restraint ofclaim 12, wherein the powered drive unit is an electric motor.

16. A vehicle restraint mountable near a loading dock for engaging a RIG (rear impact guard) of a vehicle, wherein the RIG includes an upper surface, a lower surface, a left lateral surface, and a right lateral surface that is closer to the loading dock than the left lateral surface, the vehicle restraint comprising:

a barrier assembly vertically movable relative to the loading dock;

a RIG sensor coupled to the barrier assembly, the RIG sensor providing a signal in response to the RIG being in a preferred capture area relative to the barrier assembly; and

a powered drive unit coupled to the barrier assembly such that the powered drive unit can move the barrier assembly relative to the loading dock, the powered drive unit being responsive to the signal such that:

a) the powered drive unit moves the barrier assembly toward the RIG until it receives the signal from the RIG sensor indicating that the RIG is positioned in the preferred capture area,

b) after receiving the signal, the powered drive unit is de-energized, and

c) after the powered drive unit is de-energized, the signal triggers the powered drive unit to be re-energized to further move the barrier assembly toward the RIG until the RIG is in the preferred capture area.

17. The vehicle restraint ofclaim 16, wherein the preferred capture area is an area in which at least a portion of the barrier assembly is below the lower surface, above the upper surface, and further from the dock face than the left lateral surface.

18. The vehicle restraint ofclaim 16, wherein the barrier assembly comprises a rotating hook.

19. The vehicle restraint ofclaim 16, wherein the barrier assembly comprises a vertical elongate member with an upper tip that extends horizontally toward the loading dock.

20. The vehicle restraint ofclaim 16, wherein the powered drive unit is an electric motor.

21. A vehicle restraint mountable to a loading dock for engaging a RIG (rear impact guard) of a vehicle, wherein the vehicle restraint includes a track mountable to the loading dock and a track follower vertically movable along the track upon interaction with the RIG, the vehicle restraint comprising:

a barrier rotatably coupled to the track follower, wherein the barrier helps define a RIG-receiving throat area in which the RIG may be positioned and the barrier includes a distal end and further defines a variable horizontal distance between the distal end and the track;

a RIG sensor coupled to at least one of the track follower and the barrier, the RIG sensor providing a signal in response to the RIG's position relative to the RIG-receiving throat area; and

a powered drive unit coupled to the barrier such that the powered drive unit can rotate the barrier relative to the track follower between a blocking position and a stored position, the powered drive unit being responsive to the signal such that:

a) the powered drive unit rotates the barrier toward the RIG after the RIG forces the track follower downward,

b) after rotating the barrier toward the RIG, the powered drive unit is de-energized, and

c) after the powered drive unit is de-energized, the signal triggers the powered drive unit to be re-energized to further rotate the barrier upward, thereby reducing the variable horizontal distance between the track and the distal end of the barrier.

22. The vehicle restraint ofclaim 21, further comprising a resilient member coupled to the track follower, wherein the resilient member urges the track follower upward.

23. The vehicle restraint ofclaim 21, further comprising a ramp disposed on the track follower and being engageable by the RIG such that the RIG can force the track follower downward as the vehicle backs the RIG over the ramp.

24. The vehicle restraint ofclaim 21, wherein the barrier comprises a first plate and a second plate that define a space therebetween, and the RIG sensor is movable within that space.

25. The vehicle restraint ofclaim 21, wherein the powered drive unit is an electric motor.

26. The vehicle restraint ofclaim 21, further comprising a barrier sensor in addition to the RIG sensor, the barrier sensor is coupled to at least one of the track follower and the barrier, the barrier sensor provides a stored-signal that triggers the powered drive unit to stop lowering the barrier when the barrier reaches the stored position.

27. The vehicle restraint ofclaim 21, wherein the RIG sensor includes a sensing arm pivotally coupled to the barrier such that the sensing arm can pivot into the RIG-receiving throat area.

28. The vehicle restraint ofclaim 21, wherein the RIG sensor includes an optical beam that helps define the RIG-receiving throat area.

29. The vehicle restraint ofclaim 21, wherein the signal has a first state and a second state, the first state triggers the motor to be energized, and the second state triggers the motor to be de-energized.

30. The vehicle restraint ofclaim 21, wherein when the RIG is captured by the barrier within the RIG-receiving throat area, and the RIG subsequently moves, the barrier responds by:

translating upward under the impetus of the resilient member when the RIG moves upward, and

rotates upward under the impetus of the powered drive unit when the RIG moves horizontally toward the track.

Images