U.S. patent application number 11/551032 was filed with the patent office on 2008-04-24 for vehicle restraint with bi-directional sensor.
This patent application is currently assigned to RITE-HITE HOLDING CORPORATION. Invention is credited to Jonathan Andersen, Timothy Cotton, Kurt Lessard, Ben Wieberdink.
Application Number | 20080095598 11/551032 |
Document ID | / |
Family ID | 39204045 |
Filed Date | 2008-04-24 |
United States Patent
Application |
20080095598 |
Kind Code |
A1 |
Cotton; Timothy ; et
al. |
April 24, 2008 |
VEHICLE RESTRAINT WITH BI-DIRECTIONAL SENSOR
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.
Inventors: |
Cotton; Timothy; (Milwaukee,
WI) ; Andersen; Jonathan; (Grafton, WI) ;
Lessard; Kurt; (S. Milwaukee, WI) ; Wieberdink;
Ben; (Cedar Grove, WI) |
Correspondence
Address: |
HANLEY, FLIGHT & ZIMMERMAN, LLC
150 S. WACKER DRIVE, SUITE 2100
CHICAGO
IL
60606
US
|
Assignee: |
RITE-HITE HOLDING
CORPORATION
Milwaukee
WI
|
Family ID: |
39204045 |
Appl. No.: |
11/551032 |
Filed: |
October 19, 2006 |
Current U.S.
Class: |
414/401 ; 188/31;
414/396; 414/402; 414/584; 414/809 |
Current CPC
Class: |
B65G 69/003
20130101 |
Class at
Publication: |
414/401 ;
414/396; 414/402; 414/584; 188/31; 414/809 |
International
Class: |
B65G 67/00 20060101
B65G067/00; B60T 1/00 20060101 B60T001/00; B65F 9/00 20060101
B65F009/00 |
Claims
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 of claim 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 of claim 1, further comprising illuminating a light
in response to sensing that the front surface is no longer
horizontally adjacent the barrier.
4. The method of claim 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 of claim 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 of claim 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 of claim 7, further comprising moving the distal end
vertically and horizontally in response to sensing horizontal
movement of the RIG.
9. The method of claim 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 of claim 7, further comprising illuminating a light
in response to sensing horizontal movement of the RIG.
11. The method of claim 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 of claim 12, wherein the barrier
comprises a rotating hook.
14. The vehicle restraint of claim 12, wherein the barrier
comprises a vertically elongate member.
15. The vehicle restraint of claim 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 of claim 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 of claim 16, wherein the barrier assembly
comprises a rotating hook.
19. The vehicle restraint of claim 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 of claim 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 of claim 21, further comprising a
resilient member coupled to the track follower, wherein the
resilient member urges the track follower upward.
23. The vehicle restraint of claim 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 of claim 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 of claim 21, wherein the powered drive
unit is an electric motor.
26. The vehicle restraint of claim 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 of claim 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 of claim 21, wherein the RIG sensor
includes an optical beam that helps define the RIG-receiving throat
area.
29. The vehicle restraint of claim 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 of claim 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.
Description
FIELD OF THE DISCLOSURE
[0001] 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
[0002] 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.
[0003] 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.
[0004] 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.
[0005] 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.
[0006] 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.
[0007] 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
[0008] 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.
[0009] 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.
[0010] In some examples, the vehicle restraint includes a
dual-plate barrier with a RIG sensor protectively interposed
between the two plates.
[0011] In some examples, the RIG sensor includes an optical
device.
[0012] In some examples, the RIG sensor includes a pivotal arm.
[0013] 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.
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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
[0018] FIG. 1 is a right side view of a vehicle restraint with its
track follower raised and its barrier in a stored position.
[0019] FIG. 2 is a right side view of the vehicle restraint of FIG.
1 but showing a vehicle lowering the track follower.
[0020] FIG. 3 is a right side view of the vehicle restraint of FIG.
1 but showing the vehicle's RIG on top of the track follower.
[0021] FIG. 4 is a right side view similar to FIG. 3 but showing
the barrier at its blocking position.
[0022] FIG. 5 is a right side view similar to FIG. 4 but showing
the RIG having moved away from the barrier.
[0023] FIG. 6 is a right side view similar to FIG. 5 but showing
the vehicle restraint's response to the RIG's horizontal movement
away from the barrier.
[0024] FIG. 7 is a front view of FIG. 1 but with a ramp extension
omitted to show other features of the restraint more clearly.
[0025] FIG. 8 is a right side view similar to FIG. 3 but
illustrating an alternate example.
[0026] FIG. 9 is a right side view showing another operating
position of the vehicle restraint of FIG. 8.
[0027] FIG. 10 is a right side view showing another operating
position of the vehicle restraint of FIG. 8.
[0028] FIG. 11 is a right side view showing another operating
position of the vehicle restraint of FIG. 8.
[0029] FIG. 12 is a right side view showing another operating
position of the vehicle restraint of FIG. 8.
[0030] FIG. 13 is a right side view showing another operating
position of the vehicle restraint of FIG. 8.
[0031] FIG. 14 is a right side view similar to FIG. 3 but
illustrating yet another example.
[0032] FIG. 15 is a right side view showing another operating
position of the vehicle restraint of FIG. 14.
[0033] 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.
[0034] FIG. 17 is a right side view of the vehicle restraint of
FIG. 16 but showing the vehicle's RIG engaged by the barrier
assembly, wherein the barrier assembly is in its blocking
position.
[0035] FIG. 18 is similar to FIG. 17, but shows an enlarged view of
the barrier assembly in its blocking position.
[0036] FIG. 19 is similar to FIG. 18, but shows another mechanism
for horizontally positioning the barrier.
DETAILED DESCRIPTION
[0037] To help prevent a vehicle 10 (e.g., truck, trailer, etc.)
from accidentally pulling too far away from a dock face 12 of a
loading dock 14, a vehicle restraint 16 includes a barrier 18 for
engaging or capturing a RIG 20, or ICC bar, of vehicle 10 as the
vehicle is being loaded or unloaded of its cargo. Because vehicle
10 typically has some incidental movement during loading and
unloading operations, vehicle restraint 16 includes a RIG sensor 22
and other structure that enables restraint 16 to properly respond
to such movement. FIGS. 1-6 are right side views illustrating the
operating sequence of vehicle restraint 16, and FIG. 7 is a front
view of FIG. 1 (looking toward dock face 12). A ramp extension 24
is omitted in FIG. 7 to show other features of restraint 16 more
clearly.
[0038] To vertically position vehicle restraint 16 relative to RIG
20, restraint 16 comprises a track follower 26 that is movable
between a raised position (FIGS. 1 and 7) and various lowered
positions (FIGS. 2-6). The vertical movement of track follower 26
is guided by a track 28 that can be mounted to dock face 12. A
tension spring 30, or some other type of resilient member, biases
track follower 18 to its raised position (FIGS. 1 and 7), thus
urging track follower 26 up against the underside of RIG 20 when
RIG 20 is positioned above track follower 26 as shown in FIGS.
3-6.
[0039] In order to capture RIG 20 and thus limit its movement away
from dock face 12, track follower 26 carries rotatable barrier 18
that a powered drive unit 32 (e.g., an electric motor, hydraulic
motor, piston/cylinder, etc.--see FIG. 7) can rotate between a
stored position (FIGS. 1, 2, 3 and 7) and various blocking
positions (FIGS. 4, 5 and 6).
[0040] Although the actual operation of vehicle restraint 16 may
vary, FIGS. 1-6 illustrate an example. Operation may begin as shown
in FIG. 1, where vehicle 10 is backing into dock 14 while track
follower 26 is at its raised position, and barrier 18 is at its
stored position.
[0041] In FIG. 2, vehicle 10 continues backing into dock 14, which
forces RIG 20 to slide over a ramp 34 or to engage some other type
of mechanical structure that enables vehicle 10 to force track
follower 26 down underneath RIG 20. In this example, the
interaction between ramp 34 and RIG 20 forces track follower 26
downward against the upward urging of spring 30.
[0042] In FIG. 3, vehicle 10 is shown having backed RIG 20 over
track follower 26 such that RIG 20 passes over the top of a distal
end 36 of barrier 18. RIG 20 is now in a position where barrier 18
can rise to capture RIG 20.
[0043] In FIG. 4, power unit 32 (FIG. 7) rotates barrier 18 from
its stored position to a blocking position to help contain RIG 20
at a location that ensures a certain amount of lip purchase 42 or
overlap between a lip 38 of a conventional dock leveler 40 and a
rear edge 44 of vehicle 10. Once barrier 18 rises to its blocking
position, dock leveler 40 can be operated in a conventional manner
to set lip 38 upon the vehicle's truck bed as shown in FIG. 4.
[0044] Although the initial energizing of power unit 32 to raise
barrier 18 could be done automatically in response to some type of
sensor that senses the arrival of vehicle 10 or RIG 20, in some
cases the initial energizing of power unit 32 is simply triggered
by a conventional manually operated switch. Once energized, power
unit 32 continues raising barrier 18 until RIG sensor 22 determines
that RIG 20 is within a RIG-receiving throat area 44, or preferred
capture area, of barrier 18. Once RIG sensor 22 determines that RIG
20 is within the RIG-receiving throat area 22, or preferred capture
area, power unit 32 is de-energized, thereby stopping upward
movement of barrier 18. RIG sensor 22 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.
[0045] 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.
[0046] 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
of RIG sensor 22 may vary, the sensor will provide the
aforementioned benefits. In some examples, RIG sensor 22 comprises
a sensing arm 46 pivotally coupled to barrier 18 by way of a shaft
48 or some other pivotal connection. RIG sensor 22 may further
comprise a spring 50, a mechanical stop 52, and a limit switch 54
(proximity switch, electromechanical switch, etc.). In this example
of RIG sensor 22, arm 46 can pivot between mechanical stop 52 and
switch 54, while spring 50 biases arm 46 toward stop 52. Switch 54
provides a make or break signal 56 (FIG. 7) whose on/off states are
determined by whether arm 46 is adjacent switch 54.
[0047] In FIG. 3, arm 46 is up against stop 52, so signal 56 allows
power unit 32 to be energized via the manually operated switch
mentioned earlier. Once energized, barrier 18 continues to rise
until the engagement between arm 46 and RIG 20 forces arm 46 to
trigger switch 54. This causes switch 54 to change state such that
signal 56 now de-energizes power unit 32 to stop barrier 18 at its
blocking position of FIG. 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.
[0048] With barrier 18 restraining RIG 20 and lip 38 safely resting
upon the vehicle's truck bed, as shown in FIG. 4, vehicle 10 can
now be safely loaded or unloaded of its cargo using dock leveler 40
as a bridge for personnel and material handling equipment to travel
to and from vehicle 10. Switch 54 and signal 56 can also be
electrically coupled to a signaling system, such as lights or
audible alarms. For example, engagement between arm 46 and RIG 20
forces arm 46 to trigger switch 54, thereby causing it to change
state such that signal 56 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.
[0049] 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 allow vehicle 10
to rise and descend accordingly. Track follower 26 can readily
follow such vertical movement and stay in contact with the
underside of RIG 20 by virtue of spring 30, which urges track
follower 26 upward.
[0050] In the position shown in FIG. 4, distal end 36 of barrier 18
is a horizontal distance 58 from track 28. According to an
advantageous feature of this design, the length of distance 58 may
vary. Vehicle 10, for instance, could subsequently move
horizontally away from its position shown in FIG. 4 to its position
shown in FIG. 5 where RIG 20 is up against a dock bumper 60. To
eliminate the horizontal gap between barrier 18 and RIG 20, the
depicted restraint can sense the gap and re-position barrier 18 to
eliminate it. In this example, the horizontal movement would allow
arm 46 to return to its position against stop 52, whereby signal 56
would re-energize power unit 32 to once again rotate barrier 18
toward RIG 20. Barrier 18 would continue rotating until RIG 20
forces arm 46 away from stop 52 to re-trigger switch 54, whereby
signal 56 would then stop barrier 18 at its newly adjusted blocking
position of FIG. 6. Horizontal distance 58' of FIG. 6 is less than
distance 58 of FIG. 5, so RIG 20 is more constrained in FIG. 6 than
in FIG. 5. Reducing or eliminating the horizontal backlash of RIG
20 within restraint 16 may reduce the possibility of RIG 20
hammering against barrier 18 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.
[0051] 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.
[0052] Although these functions could be accomplished by various
structures, FIGS. 1-7 illustrate one example. In the illustrated
example, track follower 26 comprises two side plates 26a and 26b
attached to a base 62. Rollers 64 or slide members extending from
side plates 26a and 26b and protruding into two vertical channels
of track 28 help guide the vertical movement of track follower 26.
To urge track follower 26 upward, one or more springs 30 extend
between base 62 and an upper anchor 66 affixed to track 28.
Although barrier 18 could be a single hook-shaped member, barrier
18 comprises two plates 18a and 18b that help protect RIG sensor 22
therebetween. Plates 18a and 18b can be keyed to shaft 48 to
provide a positive drive connection to drive unit 32. A chain 68
and two sprockets 70 and 72 can couple the output of drive unit 32
to shaft 48. For overload protection, a slip clutch 74 can be
installed somewhere in the drive train between shaft 48 and drive
unit 32, although the current sensing configuration may allow the
slip clutch to be eliminated. One end 74 of spring 50 can be
attached to plate 18b, and an opposite end 76 can be attached to
arm 46. Stop 52 can be a pin or some other suitable structure
extending from barrier 18. At least part of RIG sensor 22 can be
attached at an appropriate location on barrier 18. Restraint 16
also may include a barrier sensor 78 coupled to track follower 26.
Barrier sensor 78 provides a stored-signal 80 (FIG. 7) that
triggers powered drive unit 32 to stop lowering barrier 18 when the
barrier reaches its stored position.
[0053] In the example of FIGS. 1-7, barrier 18 is keyed or
otherwise solidly fixed to shaft 48 while arm 46 can rotate about
shaft 48. In an alternate example, however, generally the opposite
is true. More specifically, FIGS. 8-13 show a vehicle restraint 82
whose barrier 84 can rotate relative to a shaft 86, but an arm 88
is rigidly fixed to shaft 86. A tension spring 90, which extends
between arm 88 and barrier 84, urges barrier 84 upward relative to
arm 88. In this case, spring 90 is sufficiently strong to support
the barrier's weight. The operation of vehicle restraint 82 may be
as follows:
[0054] FIG. 8 corresponds to FIG. 3. Vehicle 10 just placed its RIG
20 upon vehicle restraint 82. Barrier 84 is at its stored position,
and arm 88 is resting upon stop member 91. The tension in spring 90
holds barrier 84 slightly above arm 88.
[0055] In FIG. 9, drive unit 32 (FIG. 7) is raising arm 88 via
shaft 86, and barrier 84 rises with arm 88 due to spring 90.
[0056] In FIG. 10, barrier 84 makes initial contact with RIG 20;
however, drive unit 32 (FIG. 7) continues raising arm 88 because
arm 88 has not yet tripped switch 54.
[0057] FIG. 11 shows arm 88 having tripped switch 54, which
de-energizes power unit 32 (FIG. 7). The tripping of switch 54
indicates that RIG 20 is in the preferred capture area, that is,
properly positioned relative to barrier 84. Tripping of switch 54
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 this point
vehicle restraint 82 remains substantially stationary as long as
RIG 20 remains still. In this situation, the tension in spring 90
causes barrier 84 to maintain some spring loaded-pressure against
RIG 20. To prevent RIG 20 from forcing barrier 84 down past the
elevation of arm 88, barrier 84 includes a stop block 55 that
limits the relative rotation between barrier 84 and arm 88.
[0058] If RIG 20 moves slightly closer to dock face 12, as shown in
FIG. 12, barrier 84 will tend to follow that movement due to the
urging of spring 90. If the movement of RIG 20 and the relative
movement of arm 88 are small, such that RIG 20 remains in the
preferred capture area, then barrier 84 may be able to follow the
RIG's movement without drive unit 32 having to be re-energized by
switch 54. If, however, the movement of RIG 20 and the relative
movement of arm 88 are sufficient to trip switch 54, indicating
that a horizontal gap has developed between barrier 84 and RIG 20
(i.e., RIG 20 has moved out of the preferred capture area), then
drive unit 32 is re-energized by switch 54 to force arm 88 and
barrier 84 back up against the RIG, in its new position, as shown
in FIG. 13. Thus, vehicle restraint 82 can closely follow
incidental movement of RIG 20 by spring force alone and follow
greater movement by automatically energizing power unit 32 when a
horizontal gap forms between barrier 84 and RIG 20 such that RIG 20
moves out of the preferred capture area. With this design, drive
unit 32 could be energized less often. Also, arm 88 never needs to
actually contact RIG 20, so arm 88 could be completely hidden
inside or underneath barrier 84. 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.
[0059] FIGS. 14 and 15 illustrate yet another example of a vehicle
restraint 92 that is similar vehicle restraint 16 of FIGS. 1-7,
wherein FIGS. 14 and 15 correspond to FIGS. 3 and 4 respectively.
With vehicle restraint 92, RIG sensor 22 is replaced by an optical
beam 94 or comparable electromagnetic field emitted and/or received
by a field type sensor 96 mounted to a barrier 98. A beam reflector
100 may or may not be needed depending on the chosen style of
sensor 96. With vehicle restraint 92, the presence of RIG 20 in the
preferred capture area can be detected by RIG 20 interrupting beam
94 rather than by displacing arm 46.
[0060] Yet another example of a vehicle restraint 102 is shown in
FIGS. 16-18. Like the previous examples, vehicle restraint 102 is
intended to help prevent a vehicle 10 (e.g., truck, trailer, etc.)
from accidentally pulling too far away from a dock face 12 of a
loading dock 14. 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 restraint 102, as shown in FIGS. 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-moving barrier assembly 104. Barrier assembly 104
comprises a barrier 114, a sliding barrier 116, a RIG sensor 118, a
RIG sensor extension 122, and a RIG sensor switch 124. FIGS. 16-18
are right side views illustrating the operating sequence of vehicle
restraint 102.
[0061] FIG. 16 shows barrier assembly 104 in a stored position,
wherein the barrier assembly is protected by housing 106. Barrier
assembly position sensor 108 is also protected by housing 106 and
senses when barrier assembly 104 is in its stored position. After
vehicle 10 is backed into a loading/unloading position against
loading dock bumper 60, as shown in FIG. 17, the vehicle restraint
may be actuated, energizing lifting cylinder 110 and causing it to
extend. As lifting cylinder 110 extends, it exerts a force against
barrier assembly 104 causing rollers 112 to travel upward within
roller track 134, which can be mounted to dock face 12. Barrier
assembly 104 can be attached to rollers 112 such that barrier
assembly 104 moves with rollers 112. Barrier assembly 104 continues
to travel upward until barrier 114 contacts RIG 20. Contact with
RIG 20 prevents barrier assembly 104 from moving any further
upward, thereby causing the pressure in lifting cylinder 110 to
rise. Once the internal pressure of lifting cylinder 110 reaches a
pre-determined threshold, a second cylinder, sliding cylinder 120,
is energized. Once energized, sliding cylinder 120 retracts,
causing sliding barrier 116 to move horizontally toward dock face
12. Sliding barrier 116 moves horizontally toward dock face 12
until RIG sensor 118 contacts RIG 20. RIG sensor 118 is pivotally
mounted to sliding barrier 116 and biased to the rest position
shown in FIG. 16, such that continued horizontal movement of
sliding barrier toward dock face 12 causes RIG sensor 118 to rotate
until RIG sensor extension 122 actuates RIG sensor switch 124. 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 of RIG sensor
switch 124 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. When RIG sensor switch
124 detects that the RIG is in a preferred capture area, it causes
both sliding cylinder 120 and lifting cylinder 110 to cease
extending, resulting in the barrier assembly in the engaged
position shown in FIGS. 17 and 18. Furthermore, RIG sensor switch
124 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.
[0062] As shown best in FIGS. 17 and 18, sliding barrier 116
includes an extension tip 126 that extends over the top of a
portion of the RIG. Like the rotating hook restraint shown in FIGS.
1-15, but unlike a traditional vertically-moving barrier, extension
tip 126 provides a barrier to upward movement of the RIG. Thus, in
the event that the trailer's landing gear collapses, extension tip
116 will help prevent the RIG (and the rear of the trailer) from
rapidly moving upward. As detailed above, RIG sensor 118 acts to
ensure that RIG 20 is consistently positioned relative to sliding
barrier 116 and extension tip 126 (with RIG 20 in the preferred
capture area), such that extension tip 126 extends over a portion
of RIG 20.
[0063] 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 allow barrier assembly 104 to follow RIG 20 as it
floats slightly, the lower end 130 of lifting cylinder 110 is
slidably mounted and attached to float spring 128. If RIG 20 moves
slightly downward, float spring 128 allows barrier assembly 104 to
follow such movement, and if RIG 20 moves back upward to its
original position, float spring 128 urges barrier 114 upward, in
contact with RIG 20. Thus, if the RIG moves a relatively small
amount, barrier assembly 104 may be able to follow the RIG's
movement without the need for lifting cylinder 110 to be
re-energized.
[0064] However, vertical movement of the RIG is typically
accompanied by horizontal movement of the RIG. If RIG 20 moves
horizontally closer to dock face 112, then a horizontal gap would
result between the barrier and RIG 20, such that RIG 20 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,
RIG 20 may lose contact with RIG sensor 118, resulting in RIG
sensor 118 returning to its rest position and RIG sensor extension
122 losing contact (e.g., magnetic contact or physical contact)
with RIG sensor switch 124. When engagement between RIG sensor
extension 122 and RIG sensor switch 124 is lost (indicating that
the RIG is no longer in the preferred capture area), lifting
cylinder 110 is re-energized and, once its internal pressure
reaches the pre-determined level (as detailed above), sliding
cylinder 120 is re-energized. Re-energizing sliding cylinder 120
causes it to retract, which, in turn, causes sliding barrier 116 to
move horizontally toward dock face 12 to minimize the horizontal
gap that has formed between RIG 20 and sliding barrier 116. Sliding
barrier continues to move horizontally until RIG sensor 118
contacts RIG 20 and RIG sensor extension 122 is re-engaged with RIG
sensor switch 124. Barrier assembly 104 is thereby returned to its
engaged position, wherein RIG 20 is in the preferred capture area.
Thus, RIG sensor 118 helps ensure that RIG 20 is consistently and
properly positioned relative to sliding barrier 116 and extension
tip 126 (i.e., in the preferred capture area). Furthermore, RIG
sensor 118 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 to RIG
sensor 118 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.
[0065] As described, when the RIG is properly positioned relative
to the barrier assembly, float is accommodated via float spring
128, pullout protection is provided via barrier 114, and vertical
movement of the trailer and RIG is prevented by extension tip
126.
[0066] 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).
[0067] FIG. 19 shows an example that is similar to that shown in
FIGS. 16-18, but in this version, sliding cylinder 120 has been
replaced by compression spring 132. As in the previous examples,
when the vehicle restraint is actuated, lifting cylinder 110 is
energized, causing it to extend. As lifting cylinder 110 extends,
it exerts a force that has both a horizontal and a vertical
component. The vertical force component is exerted against barrier
assembly 104, whereas the horizontal force component is exerted
against spring 132. Spring 132 has a spring constant that is
sufficient to temporarily resist the horizontal force component
exerted by lifting cylinder 110, thereby allowing the vertical
force component exerted on barrier assembly 104 to cause rollers
112 to travel upward within roller track 134. Barrier assembly 104
can be attached to rollers 112 such that barrier assembly 104 moves
with rollers 112, as in previous examples. Barrier assembly 104
continues to travel upward until barrier 114 contacts RIG 20.
Contact with RIG 20 resists the vertical force component exerted by
lifting cylinder 110 and prevents barrier assembly 104 from moving
any further upward, thereby causing the pressure in lifting
cylinder 110 to rise and the horizontal force component to
increase. Eventually, the horizontal force component exerted by
lifting cylinder 110 reaches a level that can no longer be resisted
by spring 132 and spring 132 is compressed. As spring 132 is
compressed, sliding barrier 116 moves horizontally toward dock face
12 until RIG sensor 118 contacts RIG 20. RIG sensor 118 is
pivotally mounted to sliding barrier 116 and biased to the rest
position shown in FIG. 16, such that continued horizontal movement
of sliding barrier toward dock face 12 causes RIG sensor 118 to
rotate until RIG sensor extension 122 actuates RIG sensor switch
124. Actuation of RIG sensor switch 124 causes lifting cylinder 110
to cease extending, resulting in the barrier assembly in its
engaged position as shown in FIG. 19. As in the example of FIGS.
16-18, RIG sensor 118 helps ensure that RIG 20 is consistently and
properly positioned relative to sliding barrier 116 and extension
tip 126 (i.e., RIG 20 is in the preferred capture area, such that
extension tip 126 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 via float spring 128,
pullout protection is provided via barrier 114, and vertical
movement of the trailer and RIG is prevented by extension tip
126.
[0068] 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 to vehicle restraints 16, 82 and 92 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:
* * * * *