Wirelessly operated hydraulic tail gate system

A truck having a truck body with lift track and a battery electrically connected to the body and a platform for moving along the lift track. A box holding a hydraulic unit with solenoid valves for moving the platform is attached to the truck body. A movable wireless switch having an internal power source is on the platform. When a user operates a switch the movable wireless switch emits a movement signal from a movable antenna electrically connected to the truck body. A fixed wireless switch is on the truck body. When a user operates a switch the fixed wireless switch emits a movement signal from an antenna electrically connected to the body. A wireless receiver receives the movement signal and then applies control signals to the hydraulic unit. The wireless receiver also receives a sensor signal and emits an alert if the hydraulic unit has a problem.

FIELD OF THE INVENTION

The presently disclosed subject matter is directed to hydraulic tail gates. More particularly, it is directed to wireless hydraulic tail gates.

BACKGROUND OF THE INVENTION

One of the most difficult problems when making deliveries with a truck is loading and unloading the truck. Some locations have loading docks at the same height as the truck bed to facilitate loading and unloading. Such locations support fast loading, stacking and unloading of cargo being carried on the truck by using pallet jacks, lift trucks and other cargo handling equipment.

Properly configured loading docks are highly useful and efficient. But not all locations have such docks. Almost all local deliveries and cargo pickups are performed at ground level. This leaves a gap of several feet from moving cargo from the truck bed to ground or from the ground to the truck bed. In some particular applications it has been found useful to simply carry a lift truck on the back of the cargo truck to assist loading and unloading cargo. Unfortunately this involves a significant amount of money, difficulty in using the lift truck, difficulty in carrying the lift truck so that is can be rapidly positioned at ground level, and it can be dangerous. Furthermore such an approach is useless at some locations where the ground is less than ideal or in operations not suitable for carried lift trucks.

One solution to the problem of loading and unloading cargo onto and from trucks is the use of hydraulically powered tail gates (also referred to as lift gates). Such tail gates are platforms that are attached to the back of the truck and which can hydraulically raise or lower a load to and from ground onto and from the truck bed. Tail gates have proven themselves as highly valuable devices that greatly ease the difficulty of loading and unloading trucks.

While tail gates are widely used they are not without problems. One serious problem with prior art tail gates is that they require wired electrical switches to operate and control the hydraulic pump unit that actually moves the tail gate. For convenience at least some of those wires and electrical switches are located proximate the tail gate itself. Given the rugged conditions that exist in moving cargo it is not surprising that damage to the wiring or electrical switches is very common. Such damage can be costly and time consuming to repair while resulting in some cargo not being loaded or unloaded until the damage is fixed.

In view of the problems with prior art hydraulic tail gates a hydraulic tail gate system having increased reliability would be beneficial. Beneficially such a hydraulic tail gate system would enable simplification of the electrical system required for its operation. In practice such a hydraulic tail gate system would be particularly useful if it eliminated the need for expensive high current switches and wires. Preferably such a hydraulic tail gate system could be incorporation into new trucks or implemented as a retrofit kit for existing hydraulic tail gates. Such a hydraulic tail gate system would be even better if it implemented a sensor system for checking system status and failure diagnostics.

BRIEF SUMMARY OF THE INVENTION

The principles of the present invention provide for wirelessly operated truck hydraulic tail gate systems having increased reliability and which can simplify the electrical wiring of a hydraulic tail gate by eliminating wires, switches, and possibly relays. The wirelessly operated hydraulic truck tail gate system enables replacement of high current switches and wires with lower current switches and wires. The wirelessly operated truck hydraulic tail gate system is suitable for incorporation into new vehicles or as a retrofit kit for existing hydraulic tail gates.

A truck in accord with the present invention includes a truck body having a truck power source in electrical communication with said truck body. The truck further includes a vertical lift track attached to the truck body, a movable platform for moving along the lift track, a box attached to the truck body and a hydraulic system having a hydraulic unit within the box with the hydraulic unit including internal solenoid valves that operate in accord with control signals. A movable wireless switch is attached to the platform. The movable wireless switch includes a movable switch power source that powers both a movable switch controller and a movable switch RF transmitter having a movable antenna. The movable wireless switch further includes a user-accessible movable switch that is operatively connected to the movable switch controller. When the movable switch is switched the movable switch controller causes the movable switch RF transmitter to emit a movement signal from the movable antenna. In addition, the truck includes a fixed wireless switch on said body and having a fixed switch power source that powers both a fixed switch controller and a fixed switch RF transmitter having a fixed antenna. The fixed wireless switch includes a user-accessible fixed switch that is operatively that is connected to the fixed switch controller. When the fixed switch is switched the fixed switch controller causes the fixed switch RF transmitter to emit a movement signal from the fixed antenna. In addition, the truck also includes a wireless receiver powered by the truck power source. The wireless receiver having a receiver controller operatively connected to a receiver having a receiver antenna. When the receiver antenna receives a movement signal the receiver applies the movement signal to the receiver controller which decodes the movement signal and applies decoded switching signals as the control signals.

Beneficially, the movable antenna and/or the fixed antenna are operatively connected to the truck body. The box may include relays and the control signals are then applied to the relays. Alternatively the control signals are applied to the hydraulic unit. In practice the truck power source is a battery which may be in the box. The movement signal may cause the platform to rise or fold up. Preferably the movable switch is at least a three position switch and the fixed switch is at least a three position switch. Usefully the movable antenna is bolted to the truck body. In addition there may be at least one sensor that is operatively connected to the receiver controller wherein the at least one sensor provides the receiver controller with an operating condition of the hydraulic system. If so, the truck may then further include alert, typically an audio alarm, is operatively connected to the receiver controller to provide an alarm when the operating condition is faulty.

A hydraulic lift that is in accord with the present invention includes a metallic truck body; a lift track attached to the truck body, a metallic platform for moving along the lift track and which is electrically connected to the truck body. Also included are a metallic box attached to the truck body, a truck power source within the box, and a hydraulic system that includes a hydraulic unit within the box. That hydraulic unit includes solenoid valves that operate in accord with control signals. A movable switch device is attached to the platform. The movable switch device has a movable power source that powers both a movable controller and a movable RF transmitter having a movable antenna which attached to the metallic platform. The movable switch device further includes a user-accessible movable switch that is operatively connected to the movable controller. When the movable switch is switched the movable controller causes the movable RF transmitter to emit a movement signal from the movable antenna. Also included is a fixed switch device on said the truck body. The fixed switch device has a fixed switch power source that powers both a fixed controller and a fixed RF transmitter having a fixed antenna that is electrically connected to the truck body. The fixed switch device further includes a user-accessible fixed switch that is operatively connected to the fixed controller. When the fixed switch is switched the fixed controller causes the fixed RF transmitter to emit a movement signal from the fixed antenna. Also included is a receiver device powered by the truck power source. The receiver device has a receiver controller operatively connected to a receiver having a receiver antenna. When the receiver antenna receives a movement signal the receiver applies the movement signal to the receiver controller which decodes the movement signal and applies decoded switching signals as control signals.

In practice the box may include relays and wherein the control signals are applied to the relays. Alternatively, the control signals may be are applied to the hydraulic unit. The movement signal causes the platform to lower or it may cause the platform to unfold.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is depicted inFIGS. 2 through 7whileFIG. 1illustrates a prior art system which is useful for illustrating how the present invention differs from the prior art. However, the invention is not limited to the specifically described and illustrated embodiments. A person skilled in the art will appreciate that many other embodiments of the invention are possible without deviating from the basic concept of the invention. Any such work around will also fall under the scope of this invention.

The terms “a” and “an” as used herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. In addition, unless otherwise denoted all directional signals such as in, out, up, down, left, and right are taken with reference toFIG. 1.

FIG. 1illustrates a typical prior art tail gate system10. The tail gate system10includes a vertically movable metal platform12that is mounted on lift tracks13at the rear of a truck16. The platform12can be folded down, folded up, raised or lowered along the tracks13by power provided by a hydraulic pump unit18. The hydraulic pump unit18typically is housed in a metal box20that is mounted to the side of the truck16.

The hydraulic pump unit18is a typical hydraulic pump unit that includes a hydraulic unit21having an internal electric motor, a hydraulic pump, and solenoid valves. As the electric motor turns it operates the hydraulic pump. Meanwhile, electric relays26selectively energize the solenoid valves using electric power from a battery27. In operation the hydraulic unit21pressurizes a hydraulic system through the actions of its solenoid valves. This pressurizes one or more hydraulic cylinders (not shown) which raises, lowers, folds up, and folds down the platform12. As the operation of the hydraulic pump unit18is well known in the art a more detailed description is not required for the understanding of the present invention.

However, it should be understood that “hard-wired” electrical circuitry operates the relays26in the rather complex pattern required to operate the solenoid valves within the hydraulic unit21to develop the hydraulic pressures. In the prior art tail gate system10the relays26are activated by manually operated switches. Typically there are at least two sets of electric switches, one is a movable switch set36and the other is a fixed switch set38. The movable switch set36is attached to the platform12and moves up and down with that platform12. This enables operation of the platform by a person standing on the platform12. The fixed switch set38is attached to the frame of the truck16. The fixed switch set38enables operation by a person standing beside the truck16. In the tail gate system10the movable switch set36and the fixed switch set38are connected to the relays26by an electrical wiring harness40.

As noted the relays26control the solenoid valves within the hydraulic unit21. The relays26operate whenever the movable switch set36or the fixed switch set38is activated. Also as noted rather complex circuitry associated with the relays26act as a hard wired program to produce the appropriate sequence of solenoid valve actuations. Since the movable switch set36and the fixed switch set38initiate the operations of the relays12a break in the electrical wiring harness40prevents proper operation of the hydraulic unit21.

Still referring toFIG. 1, the electrical wiring harness40is typically folded into a 180 degree loop within the tracks13. This enables vertical motion of the movable switch set36and the platform12while the electrical wiring harness40remains attached to the movable switch set36. This results in repeated bending and flexing of the wires making up the electrical wiring harness40as the platform is moved. Such bending and flexing induces breaks in the wires of the electrical wiring harness40which can render the hydraulic pump unit18inoperable. In prior art the flexing of the wire harness40when the tail gate is in motion causes constant wear on the harness and leads rapidly to failure.

Compounding the wear problems with the wire harness40is that due to the complexity of the wiring required for proper switch actions the wire harness40becomes a thick set of wires that must be installed into the interior of the chassis. This makes the wire harness40expensive to manufacture, expensive to install, prone to failure, and expensive to repair.

Refer now toFIG. 2. To address the problems associated with the electrical wiring harness40the present invention provides for a hydraulic tail gate system100without a wiring harness40. Rather than incorporate a wiring harness40the hydraulic tail gate system100respectively replaces the movable switch set36and the fixed switch set38with a movable wireless switch set102and a fixed wireless switch set104that communicate with a wireless receiver106in a hydraulic assembly105. The hydraulic assembly105includes the hydraulic unit21and the battery27as described above. In one embodiment (shown inFIGS. 2 and 6) the hydraulic assembly105also includes relays26while in another embodiment (shown inFIG. 7) the hydraulic assembly105has no relays26.

By ordinary means a wireless signal would not successfully connect wireless switches to a wireless receiver configured as inFIG. 2. This is because the metal confines of the truck16would block wireless signals. As described in more detail subsequently, to overcome that problem the movable wireless switch set102and the fixed wireless switch set104use the truck16chassis as an antenna.

The movable wireless switch set102and the fixed wireless switch set104transmit encrypted movement signals by radio frequency (RF) to the wireless receiver106. The wireless receiver106is powered by the battery27which is connected through bus117with wires199. Turning toFIG. 5, the wireless receiver106includes a microcontroller113(seeFIG. 6) that decodes the encrypted movement signals received by a receiver115via its antenna187. The microcontroller113then outputs operating electrical signals on a bus117. In the embodiment shown inFIGS. 2 and 6the operating electrical signals on the bus117are applied to the relays26. The relays26then selectively energize the solenoid valves of the hydraulic unit21using electric power from the battery27to initiate the production of hydraulic pressure. In the embodiment shown inFIG. 7the operating electrical signals on the bus117are directly applied to the solenoid valves. The prior art “hard-wired” program of operation being replaced by software programming of the operating electrical signals.

The embodiment shown inFIGS. 2 and 6mimics the signals that would have existed on the replaced electrical wiring harness40. This leaves the prior art system of relays26intact. This approach is highly beneficial for retrofitting the present invention into existing hydraulic tail gates. The embodiment shown inFIG. 7directly activates the solenoid valves. This eliminates the relays26and the complex hardwired programming they implement. This approach is well suited for use on new trucks16and is highly beneficial in reducing cost and improving reliability by eliminating the relays26while also simplifying changes to solenoid valve operations.

The wireless receiver106may be attached outside the box20or for protection against physical damage inside the box20. If mounted inside the box20either the box20will include a non-metallic section that allows radio reception or an external antenna111(seeFIG. 5).

Turning now toFIG. 3, the movable wireless switch set102includes an internal power source110such as a battery or a super capacitor or battery super capacitor hybrid charged in some manner such as with a solar panel (not shown). The internal power source110supplies electrical power to a microcontroller board121via wires111. The microcontroller board121includes an on-board microcontroller. The movable wireless switch set102also includes a transmitter125(or transceiver) having an antenna180. The transmitter125may be part of the microcontroller board121. The microcontroller board121receives inputs from a user accessible three (3) position toggle switch131. The switch antenna180is specially designed to integrate with the metal frame of the truck16. This connection is facilitated by a bolt137that connects the antenna180to the truck16. This enables the wireless communication system to overcome the Faraday cage effect of the vehicle frame which would otherwise block the signals.

When a user operates the switch131to cause the platform12to raise, a first switch input133goes HIGH. The microcontroller on the microcontroller board121senses this state and causes the transmitter125to send an encoded “raise” movement signal to the wireless receiver106. When a user operates the switch131to cause the platform12to lower a second switch input135goes HIGH. The microcontroller on the microcontroller board121senses this state and causes the transmitter125to send an encoded “lower” movement signal to the wireless receiver106. When no motion is needed switch131is left in its “OFF” state and all inputs to the microcontroller board121are LOW and the transmitter125is controlled to not send anything. The HIGH signal is achieved by way of a wire201applied to the switch by the microcontroller board121. The microcontroller board does not draw power when in the “off position.” This greatly extends the life of the power source110.

Turning now toFIG. 4, the fixed wireless switch set104also includes an internal power source110which supplies electrical power via wires111to a microcontroller board121with an on-board microcontroller. The fixed wireless switch set104also includes a transmitter125(or transceiver) having an antenna182connected to the frame of the truck16. This connection is facilitated by a bolt137that connects the antenna to the frame of the truck16. The nature of this antenna configuration enables wireless communications in a manner that overcomes the Faraday cage effect of the truck frame which would otherwise block signals. The microcontroller board121receives four (4) inputs from two different user accessible three position toggle switches143and145.

When a user operates the switch143to cause the platform12to raise a first switch input147goes HIGH. The microcontroller on the microcontroller board121senses this state and causes the transmitter125to send an encoded “raise” movement signal to the wireless receiver106. When a user operates the switch145to cause the platform12to lower a second switch input149goes HIGH. The microcontroller on the microcontroller board121senses this state and causes the transmitter125to send an encoded “lower” movement signal to the wireless receiver106. When a user operates the switch143to fold the platform12up a third switch input151goes HIGH. The microcontroller on the microcontroller board121senses this state and causes the transmitter125to send an encoded “fold” movement signal to the wireless receiver106. When a user operates the switch145to unfold the platform12a fourth switch input153goes HIGH. The microcontroller on the microcontroller board121senses this state and causes the transmitter125to send an encoded “unfold” movement signal to the wireless receiver106. When no motion is needed all inputs to the microcontroller board121are LOW and the transmitter125is controlled to send anything. Switching power for the switches143and145are supplied by the microcontroller board121via wires156. The microcontroller board does not draw power when in the “off position.” This greatly extends the life of the power source110.

Turning toFIG. 5, in response to encoded movement signals from either the movable wireless switch set102or the fixed switch set104the receiver115of the wireless receiver106receives the encoded movement signal and causes its microcontroller113to take appropriate action to cause the appropriate sequence of operation of the hydraulic valves to cause the of the hydraulic assembly105to raise, lower, fold, or unfold the platform12.

The respective antennas180and182of the movable wireless switch set102and the fixed wireless switch set104are both attached to the frame of the truck16as shown inFIGS. 3 and 4. This enables a reliable, low-power RF signal to communicate with the wireless receiver106. This is possible because the electric power of the movable wireless switch set102and the fixed wireless switch set104produced by the internal power source110are isolated from the electrical system of the truck16. By attaching the antennas180and182to the frame of the truck16the truck itself becomes the antenna, broadcasting a reliable signal from the movable wireless switch set102and the fixed wireless switch set104to the antenna187of the wireless receiver106. Thus the movable wireless switch set102and the fixed wireless switch set104can be covered and thus protected in the metal frame of the truck16which would otherwise function as a Faraday cage that would trap the RF signal thereby making communications with the wireless receiver106in the box20impossible.

The wireless receiver106is in or on the box20, gets its power from the vehicle electric system via the battery27, it therefore is not isolated from the vehicle electric system. Therefore the antenna187of the wireless receiver106is a regular antenna which for reliability is preferably mounted outside the box20or at least runs through the box20.

As previously discussed the microcontroller113generates appropriate signals either for the relays26or for the solenoid valves of the hydraulic pump21. In addition, the microcontroller113has additional inputs which are used for monitoring a sensor system191that senses operating parameters of the hydraulic pump21via wires199and a connector117. Operating parameters may include the conductivity of the solenoid coils, the voltage of the battery27, operating current, hydraulic pressures or the RF signal strengths from the movable wireless switch set102and from the fixed wireless switch set104. The outputs of the sensor system191are analyzed in real time to determine the status of the system. Should a problem be found the microcontroller113operates an internal alarm to warn of an existing or pending problem. An alarm code can be used to identify the problem. For example, short audio burst may signal a defective solenoid while a set of one (1) second long audio bursts might signal loss of hydraulic pressure. Other patterns would then signal other issues.