Wireless liftgate control system

A wireless control system can be used to selectively adjust the position of a liftgate platform with respect to a vehicle cargo hold. The wireless control system includes a transmitter for use in transmitting a wireless control signal, a receiver that receives the wireless control signal transmitted by the transmitter and communicates a corresponding control signal to an actuation device to adjust the platform and, a transmitter detection system that prevents the actuation device from operating unless the transmitter is positioned in a predetermined location.

I. BACKGROUND OF THE INVENTION

A. Field of Invention

This invention pertains to the art of methods and apparatuses for vehicle liftgates, and more specifically to a wireless control system for a vehicle liftgate.

B. Brief History

It is well known in the art to provide a liftgate on the rear of a vehicle having a cargo hold or bed. The liftgate raises and lowers on demand by engaging actuators that power the liftgate. When the liftgate is in a raised position, the liftgate platform is at the level height of the vehicle bed, and cargo can be loaded and/or unloaded from the bed. When the liftgate is in a lowered position, cargo can be loaded and/or unloaded onto the liftgate platform. Typically, the liftgate is operated with a controller that includes buttons and/or switches that, when manipulated, engage the actuators to raise and lower the liftgate.

Applicants believe that, for safety precautions, it is better to have the liftgate operator positioned relatively close to the liftgate as the liftgate platform is raised and lowered. This makes it easy for the liftgate operator to observe the operation of the liftgate and, for example, to immediately stop the motion of the liftgate platform if the cargo appears to be unsecured. Furthermore, liftgates often do not include side panels. This permits the liftgate to fold into a compact configuration during periods of non-use. Because of the open sides on the liftgate, and particularly as the liftgate is being raised, the cargo needs to be carefully watched and handled to prevent it from falling off of the liftgate. To achieve these results, it is advantageous to fix the position the liftgate control at the rear of the vehicle so that the operator is required to be relatively close to the liftgate and can easily view the cargo while operating the liftgate.

Another known aspect of liftgates relates to the wiring typically used in connecting the components of a liftgate assembly. Typically, wire harnesses or other conductors are routed through the frame structure of the vehicle and connected to a power supply and the actuators of the liftgate. This can be a cumbersome installation process particularly in after-market installations. It would be advantageous to utilize a wireless control to send signals to the actuators of the liftgate thereby reducing or eliminating conductors that may be prone to damage during use of the liftgate.

What is needed, therefore, is a liftgate control that can be easily installed without the use of cumbersome wire harnesses and that is positioned relatively close to the liftgate. Additionally, it would advantageous to provide a wireless control that can only be operated if the operator is in plain view of the liftgate.

II. SUMMARY OF THE INVENTION

According to one aspect of this invention, a wireless control system is used with a vehicle that has a cargo hold and a liftgate assembly. The liftgate assembly has a platform and an actuation mechanism for use in selectively adjusting the position of the platform with respect to the cargo hold. The wireless control system includes: (a) a transmitter for use in transmitting a wireless control signal, the transmitter having controls for selectively adjusting the platform; (b) a receiver that receives the wireless control signal transmitted by the transmitter and communicates a corresponding control signal to the actuation device to adjust the platform; and, (c) a transmitter detection system that prevents the actuation device from operating unless the transmitter is positioned in a predetermined location.

According to another aspect of the invention, the transmitter detection system includes an electric circuit that is closed only when the transmitter is in the predetermined location.

According to another aspect of the invention, the transmitter cannot transmit the wireless control signal when the electric circuit is open.

According to another aspect of the invention, the actuation device is inoperative regardless of the wireless control signal when the electric circuit is open.

According to another aspect of the invention, the wireless control system also includes a jumper circuit for use in selectively overriding the electric circuit.

According to another aspect of the invention, the wireless control signal has a unique address data and the receiver communicates the corresponding control signal to the actuation device responsive to the unique address data.

According to still another aspect of this invention, the transmitter has a self-contained power supply.

One advantage of this invention is that there is no need to route a wire harness through the vehicle structure.

Still another advantage of this invention is that the control is positioned relatively close to the liftgate so that the liftgate operator can easily observe the operation of the liftgate and the status of the associated cargo.

IV. DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein the showings are for purposes of illustrating one or more embodiments of the invention only, and not for purposes of limiting the same,FIG. 1shows a liftgate assembly, shown generally at10, mounted in one of its usual environments, on the rear vertical corner posts14of the rear end opening16of a truck5having a cargo hold17. The liftgate assembly10includes a platform24and an actuation mechanism18for use in selectively adjusting the position of the platform24with respect to the cargo hold17. The platform24is shown in its full down position inFIGS. 1 and 4and it is shown partially folded inFIG. 3. The actuation mechanism18and thus the platform24and other liftgate assembly components may be controlled using a control system51according to this invention. It is to be understood that this invention will work equally well with liftgates positioned in any conventional manner including on vans and on the sides of truck trailers.

With reference now toFIGS. 1 and 3, the actuation mechanism18may include a right hand or curb side columnar power assembly19and a left hand or street side columnar power assembly21. The curb side columnar assembly19may include a downwardly extendable and upwardly retractable runner assembly25. The street side columnar assembly21may include a companion downwardly extendable and vertically retractable runner assembly27. As will be discussed in a subsequent paragraph, the telescopically mounted runner assemblies25,27may be hydraulically operable in unison for raising and lowering the platform24between a ground level (shown inFIG. 1) and the level of a bed30of the body6. Another component of the liftgate assembly10may include a threshold plate32that is secured in a horizontally extending position to the rear edge of the bed30. The columnar assemblies19,21may be mirror image assemblies having substantially identical components. The curb side assembly19may differ in that the lower end portion of its runner assembly25may be fitted with a hydraulically powered crank mechanism, not shown, to effect movement of the platform24sections through the various stages. It should be noted that while the present embodiment discusses hydraulic actuation, this invention will also work well with any other type of actuation mechanisms18chosen with sound engineering judgment including electric actuation and pneumatic actuation. It should be further noted that while the present embodiment discusses a large platform liftgate, this invention may be applied to any type or size of liftgate.

With continuing reference toFIGS. 1 and 3, under a box-like column cap44, the upper end of each column19,21rigidly mounts a parallel, spaced apart pair of substantially vertical power cylinder support plates46oriented parallel to the major axis of the column profile and having opposite ends resting on the column front and rear walls. The support plates46may be used to support a fluid powered linear actuator or cylinder49that is suspended from a pin, located adjacent the upper end of each column19,21not shown, as to hang within the cavity of the columns19,21respectively. The lower end of the hydraulic cylinder49may be displaceable in a direction parallel to the major axis of the column19,21. It should be noted that any quantity of hydraulic cylinders49may be used. However, in this embodiment one cylinder49is used in each of the columns19,21. The cylinder49may be of either the single or double acting type and may be controlled by valves, not shown. Electrical solenoids integrated into the valves may be used to shift spools, also not shown, as is very well known in the art. Shifting of the spools may cause hydraulic fluid to flow into and out of the cylinders49for use in providing a lifting force used to raise and lower the platform24and associated cargo. An entire hydraulic system including hydraulic pump control valves, operated by electrical solenoids and associate fluid power lines may be included. In that the make up of hydraulic systems is well known in the art, no further explanation will be offered at this time.

With reference now toFIGS. 1,2and3, the actuation mechanism18may be controlled using the control system51. The control system51may comprise an electrical control54including a wire harness56that may be directly connected to the solenoids of the hydraulic system. In this manner, the electrical control54may send control signals through the wire harness56to engage the valve solenoids and subsequently the hydraulic cylinders49. In one embodiment, the control system51may be a wireless control system52. By “wireless” it is meant that the components of the control system52communicate electrically by electromagnetic signals transmitted through the air. In one embodiment, the wireless control system52may include a transmitter59for transmitting wireless signals, and a receiver63for receiving wireless signals.

With reference now toFIGS. 1 and 2, the receiver63, which may be contained in a control housing65, receives the wireless signals transmitted by the transmitter59and communicates corresponding control signals to the actuation device18to move the platform24, as described above. The receiver63may include an antenna74to aid in receiving the wireless signals sent by the transmitter59. The receiver63may include a wiring harness56, which may include electrical wires56′ for obtaining power from the vehicle5and output wiring56″ for actuating the solenoids and switches of the actuation mechanism18to adjust the platform24as described above. The receiver63may be mounted anywhere on the vehicle5or liftgate assembly10as chosen with sound engineering judgment.

With continuing reference toFIGS. 1-2, the transmitter59may generate an R.F. (Radio Frequency) signal, which may be FM (Frequency Modulated) modulated. The modulation may be a 120 bit data stream with start and stop bits, information concerning the selected switch being activated, and a specialized algorithm developed to ensure the validity of the transmission. The transmitter59may also transmit address information to enable the transmitter to “talk” to the receiver63. This address information may be set so that no two devices will be the same. The receiver63may receive the radio signal transmitted by the transmitter59, decode the data stream, and check for validity of the address and the start and stop bits of the received data. If this information is “correct,” a software algorithm may perform to accept or reject the information to be passed on to the receiver outputs. If for any reason this test fails, no output will be sent from the receiver63to activate the actuation mechanism18.

Still referring toFIGS. 1-2, the transmitter59may require a power supply, which can be a battery pack72. The battery pack72may be located within a housing74of the transmitter59, or the transmitter59may obtain its power directly from a vehicle power source. For example, power supply wires76extending from the transmitter59may be adapted to be plugged into the auxiliary power outlet or cigarette lighter of vehicle5. The transmitter59may further include an antenna74′, for purposes of aiding in the transmission of control signals to the receiver63. The transmitter59may include a plurality of joysticks, switches and/or toggle switches79for controlling the movement and positioning of the platform24or any other liftgate assembly10component. Any number and configuration of switches79may be chosen as is appropriate for use in controlling the liftgate assembly10.

With continuing reference toFIGS. 1-2, the transmitter59should be easily accessible to the operator of the liftgate assembly10. For safety precautions the transmitter59should be positioned in a convenient proximate location to the liftgate assembly10so that the operator may continuously observe movement of the platform24and any associated cargo. In one embodiment, the transmitter59is mounted permanently to the vehicle5, either within the cab of the vehicle5or at a location outside of the vehicle cab. In an alternate embodiment, the transmitter b is not permanently attached to the liftgate assembly10or the vehicle5, but instead may be portable. In this case, the transmitter59may be positioned in any desired location, including a location exterior to the vehicle5without the encumbrance wire harnesses or other electrical conductors. This is shown inFIG. 1. Of course, the transmitter59must be located within a predetermined range of receiver63so that the signals transmitted can reach the receiver b.

With reference now toFIGS. 1-2and5-6, in order to assure that the operator is physically present to observe and oversee operation of the liftgate assembly10when it is being operated, the control system51may include a transmitter detection system61that prevents the actuation device18from operating to in any way adjust the liftgate assembly10unless the transmitter59is positioned in a predetermined location. The transmitter detection system61may include an electric circuit62that is closed or completed only when the transmitter59is in the correct predetermined location. The transmitter59may be electrically connected to the circuit62so that the transmitter59can only send a wireless signal to the receiver63if the circuit62is completed. In this case, when the transmitter59is not in the predetermined location, the transmitter59cannot send a control signal (regardless of the adjustment of controls79) to the receiver63. As a result, no signal is sent by the receiver63and operation of the actuation mechanism18is prevented. In an alternate embodiment, the transmitter detection system61may not affect the transmission of the wireless signal but rather the circuit62may prevent one or more portions of the actuation mechanism18from operating. In either case, the liftgate assembly10cannot be operated unless the transmitter59is positioned in the predetermined location.

With reference now toFIGS. 1-2,5and7as noted above, the transmitter59may be mounted directly to the vehicle5, as shown inFIG. 1, in any conventional manner. The mount may be permanent or may be temporary, permitting the transmitter59to be portable, as will be discussed further below. In one embodiment, the transmitter59may have two open contacts64on the back surface of the transmitter59, as shown inFIG. 5.FIG. 7shows the circuit62for this embodiment including a battery or power source80(which could be the previously noted battery pack72), an open portion82defined by the open contacts64, a ground84and a space86which can contain other electric components as may be required. As is well known, an electric circuit is only complete (or closed) when current can flow from the power source80to ground84. When the circuit is not complete (or open) current cannot flow. As the operation of an electric circuit is well known, other details will not be provided here. For this embodiment, when the transmitter59is mounted to the vehicle5, the two open contacts64contact the metal surface of the vehicle5which bridges the open contacts64and thus completes or closes the circuit62. In this closed circuit condition, the transmitter59can be used to send a control signal to operate the actuation mechanism18. When the transmitter59is not mounted to the vehicle5, however, the open contacts64are not bridged and the circuit62remains open. In this open circuit condition, the transmitter59cannot send a control signal (or alternately, the actuation mechanism18cannot be operated).

With reference now toFIGS. 1-2,6and7-8, in another embodiment, the transmitter59may have one or more magnetic contacts67on the back surface of the transmitter59, as shown inFIG. 6. For this embodiment, the circuit62ofFIG. 7applies except that the open portion82ofFIG. 7is replaced with the open portion82ofFIG. 8. For this embodiment, when the transmitter59is mounted to the vehicle5, the magnetic contact67contacts the metal surface of the vehicle5which bridges the open portion82and thus completes or closes the circuit62. In this closed circuit condition, the transmitter59can be used to send a control signal to operate the actuation mechanism18. When the transmitter59is not mounted to the vehicle5, however, the open portion82is not bridged and the circuit62remains open. In this open circuit condition, the transmitter59cannot send a control signal (or alternately, the actuation mechanism18cannot be operated).

With reference now toFIGS. 2-4and7, in yet another embodiment, the wireless control system52may include a cradle60that holds the transmitter59in place during use. The cradle60may be constructed from metal, plastic or other material that resists corrosion from exposure to the environment. Any configuration of cradle60may be chosen that securely receives the transmitter59. The cradle60may be permanently affixed to the vehicle5, as shown, and accordingly the transmitter59may be permanently received within the cradle60. The cradle60may include an opening that allows access to the battery compartment of the transmitter59. This allows the operator to change the battery of the transmitter59as needed without removing the transmitter59from the cradle60. In one embodiment, the cradle60may be fixed in place via fasteners. Alternatively, the cradle60could be fashioned as part of the liftgate assembly10or the vehicle5. In any case, the transmitter59may be locked in place into the cradle60via a lockable latch that can only be removed for repairs or replacement of the transmitter59by an authorized individual. Still any manner of locking the transmitter59in place may be chosen with sound engineering judgment. The cradle60may include a set of contacts66. For this embodiment, the circuit62ofFIG. 7applies except that the contacts64ofFIG. 7are replaced with the contacts66ofFIG. 3. The circuit62is only closed when the transmitter59is properly seated in the cradle60to electrically connect the contacts66. In this way, if the operator removes the transmitter59from the cradle60in attempt to operate the transmitter59from a remote location, the circuit62will open and the actuation mechanism18will be prevented from operating.

With reference now toFIGS. 1-2, in another embodiment, the transmitter detection system61narrows, in proximity and direction, the effective range of transmission to the receiver63. The transmitter59may include a proximity detection device that allows transmission of the wireless signal only if the transmitter59is in direct line of sight of and proximate to the receiver63. An Infrared transmitter and detector may be incorporated into the electric circuit62and permit the circuit62to be closed (completed) only when the transmitter59, and hence the operator, is within a predetermined distance from the liftgate assembly10.

With reference now toFIGS. 1-4,7and9, in still another embodiment, the transmitter detection system61may include a jumper circuit100. The jumper circuit100can be used to override some of the electric circuit62requirements noted above. For this embodiment, the circuit62ofFIG. 7applies except that the open portion82ofFIG. 7is replaced with the open portion82ofFIG. 9. In one embodiment, the jumper circuit100is placed within the transmitter59and is selectively adjustable by an electric switch into an “on” (or closed) condition and an “off” (or open) condition. When the jumper circuit100is switched on (closed), the open contacts64are closed (as is the circuit62) by the jumper circuit100and the transmitter59can be used even when the transmitter is not mounted to the vehicle5. This permits the flexibility of manufacturing essentially the same transmitter59for use as either a permanent mount control or as a portable hand held control. In another embodiment, the jumper circuit100is placed within the cradle60and is selectively adjustable by an electric switch into an “on” (or closed) condition and an “off” (or open) condition. When the jumper circuit100is switched on (closed), the previously mentioned contacts66are closed (as is the circuit62) by the jumper circuit100and the transmitter59can be used even when the transmitter is not placed within the cradle60. This also provides flexibility of manufacturing the same transmitter59for use as either a cradle mount control or as a portable hand held control. It should be noted that when a jumper circuit100is used it is still possible to limit the distance from which the transmitter59can be used using, for example, the previously described proximity detection device.

With reference now to all the FIGURES, the wireless control system52described above has been used with a liftgate assembly10. However, it should be noted that the wireless control system52of this invention could be used with other apparatuses in other applications as well; especially when it is desirable to require that the transmitter (and thus the operator) be at a predetermined location. Non-limiting examples of other uses for the wireless control system52are cranes, car haulers, tow trucks, electric winches used at marinas to lower boats into the water, and the like.

The preferred embodiments have been described, hereinabove. It will be apparent to those skilled in the art that the above methods may incorporate changes and modifications without departing from the general scope of this invention. For example, the wireless control51, including the transmitter59and receiver63, may wirelessly operate on any type and configuration of signal modulation. Additionally, it should be understood that any form of wireless communication may be used to communicate signals from the transmitter59to the receiver63including, but not limited to, infrared, and other frequency ranges of electromagnetically generated signals. It should also be noted that any type and configuration of electrical or electronic circuitry may be utilized to construct the receiver63transmitter59and overall control system51as chosen with sound engineering judgment. It is intended to include all such modifications and alterations in so far as they come within the scope of the appended claims or the equivalents thereof.