Tailgate lift apparatus and method

Description

This US non-provisional patent application is related to U.S. Provisional Patent Application No. 61/830,112 filed Jun. 2, 2013, and claims the benefit of that filing date.

BACKGROUND

Field of Invention

The current invention relates to an apparatus and method for a truck tailgate lift apparatus.

Prior Art

The prior art includes various hydraulic, pneumatic, and motor-driven lift devices. U.S. Pat. No. 3,688,649 to Hostetler describes A hydraulically actuated lift unit wherein a vertical hydraulic cylinder is mounted for guided vertical movement relative to fixed supporting structure, the piston rod associated with the cylinder extending downwardly there from and resting upon the support structure. Means is provided for guiding vertical movement of an elongated lift column, the latter having horizontally extending load carrying means at its lower end. A pulley is mounted on the exterior of the cylinder for rotation about a horizontal axis, and a cable is entrained over the pulley and has depending ends secured to the column and the fixed supporting structure whereby vertical movement of the column is twice that of the cylinder. The relatively fixed piston rod has a passageway there through whereby hydraulic fluid can be introduced into the cylinder to force upward movement of the latter. A pair of such units can be mounted on a truck bed with the load carrying means being common to both units and pivotally mounted thereon to serve as an end gate.

U.S. Pat. No. 4,813,842 to Morton describes a tailgate apparatus for a pick-up truck comprising a frame assembly adapted to be mounted around the preexisting bumper of a vehicle after removal of the conventional tail gate. The assembly does not require removal of the truck bumper and maintains the visibility of the license plate. Lifting and raising of the tail gate is provided by spool wound flexible straps on each side powered by a geared motor. A drive shaft under the platform interconnecting the side housings is driven by the motor rotating a first spool in one of the housings so that the spools rotate together. The apparatus is light weight and reliable in operation.

U.S. Pat. No. 6,164,895 to Croswell describes a lifting attachment is disclosed for use in conjunction with a trailer hitch mounted to a vehicle. The lifting attachment includes a support assembly which is detachably connected to the trailer hitch and this support assembly includes a vertically extending support beam. The attachment includes a platform having a generally planar top and an elongated arm having one end pivotally connected to the platform and a second end pivotally connected to the support beam. A hydraulic piston and cylinder assembly is pivotally connected between the support beam and an intermediate point on the arm so that extension and retraction of the piston within the cylinder selectively raises and lowers the platform.

U.S. Pat. No. 6,893,203 to Anderson describes a liftgate/tailgate assembly for a vehicle having a chassis and a cargo area, such cargo area comprising a bed and one or more vertical sidewalls mounted to the vehicle chassis, such liftgate/tailgate assembly comprising a tailgate which, when rotated into an open tailgate position, forms a liftgate/tailgate platform to support a load to be lifted, and one or more linkage assemblies pivotably mounted to the tailgate which permit the liftgate/tailgate platform to be translated both vertically and horizontally relative to the cargo area of the vehicle, while permitting rear impact protection to be mounted on the vehicle and method for lifting a load into a vehicle cargo area.

SUMMARY OF INVENTION

In one embodiment, an Electric Powered Lift Mechanism (EPLM) Assembly is attached to a pick-up truck box rear structure, with no body modification, to create a powered up-down lift function utilizing the box's tailgate as a load platform.

In one unique example, the EPLM concept provides for the use of the standard tailgate, in the unlatched horizontal position, to move up and down within one minute carrying a maximum load of 1000 pounds. A switch via the vehicle's electric system controls the movement.

In one embodiment, the unique truck box installation process provide for the quick and simple installation with no box structure rework for fixed attachment. The installation process is as follows:

• • Disconnect the two (2) tailgate cables from the cargo box and remove the tailgate. No tools are required.
  • Insert each Side Assembly's lower collar into the cargo box's tailgate pivot pins and pivot to the vertical position at the cargo box sticker pins. Secure the lock latch to the striker pins via two (2) via attached nuts each side (FIG. 1)
  • Install the Floor Pan and secure to the lower support bracket via two (2) screws one each side.
  • Attach the Lower Support Bar via two (2) bolts one each side.
  • Connect the right side Wire Harness Assembly to the lift side Wire Harness Assembly and secure to the Floor Pan lower clips.
  • Insert the total Wire Harness Assembly to the truck trailer electrical receptacle for the system's 12-Volt system.
  • Re-install the Tailgate to the Side Assemblies. Attach the cables on each side and check closed and open load positions.

This embodiment provides for a pick-up truck tailgate power up-down lift system via electrical/mechanical components comprising an electric motor, a set of gears and a bearing screw drive shaft enclosed in two (2) assembled tubular vertical pillars each side. One portion of each pillar assembly is affixed to the Cargo Box; and one moveable tube in each assembly is attached to the Tailgate to provide for a thirty (30) inch vertical travel. In this example, the power source is from the vehicle's electric 12-volt system. The Tailgate's up-down travel is packaged rearward of the Cargo Box structure to provide clearance to the vehicle's rear bumper. A Floor Pan extension is installed to eliminate the opening between the Tailgate and the Cargo Box floor pan.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1-16 are subassembly drawings of one embodiment of the current invention as referenced in the element list below.

FIG. 17 is a side view of an EPLM device with a tailgate in a raised position.

FIG. 18 is a side view of an EPLM device with a tailgate in a lowered position.

FIG. 19 is a rear perspective view of a right side assembly of an EPLM device with a tailgate in a raised position.

FIG. 20 is a rear perspective view of a right side assembly of an EPLM device with a tailgate in a lowered position.

FIG. 21 is a schematic of the left side wire harness assembly.

FIG. 22A is rear view of the right side assembly of FIG. 16 with a motor and gear assembly.

FIG. 22B is cross section view of the right side assembly of FIG. 16 with a motor and gear assembly.

FIG. 23 is a rear perspective view of an EPLM device with a tailgate in a lowered position.

DESCRIPTION OF EMBODIMENT

Electric Powered Lift Mechanism (EPLM)

This embodiment provides an Electric Powered Lift Mechanism (EPLM).

The following element numbers are referenced in the figures.

• Pick-up 60
• rear bumper 70
• tailgate 80
• tailgate cable 81
• cargo box 85
• tailgate pivot 95
• upper cable anchor pin 96
• Electric Powered Lift Mechanism (EPLM) 100
• side assembly pivot mounting notch 101
• side assembly striker mounting slot 102
• new tailgate pivot 104
• new tailgate striker 105
• 1000 VEHICLE INSTALLATION—POWER LIFT—FIG. 1
• 2300 INNER/OUTER TUBE ASY (FINAL)
• 2300a right side INNER/OUTER TUBE ASY
• 2260 PANEL—FLOOR
• 2544 SCREW—FLOOR ATT.
• 2261 BRACE—LOWER SUPPORT
• 2262 SCREW—SUPPORT ATT.
• 2000 ELECTRICAL COMPONENT SCHEMATIC DIAGRAM—FIG. 2
• 2858 PCU CONTROL UNIT
• 2859 SWITCH—TAILGATE UP-DOWN FUNCTION
• 2860 TAIL LIGHT—LED STOP/TURN/TAIL LIGHT
• 2861 SWITCH—TAILGATE HORIZONTAL LOAD POSITION
• 2272 PANEL ASY—SIDE COLLAR ATT.—FIG. 3
• 2733 PANEL ASY—SIDE (WELD)
• 2267 COLLAR—LOWER BODY
• 2801 RIVET—COLLAR ATT
• 2300 OUTER—INNER TUBE ASY (FINAL)—FIG. 4
• 2526 INNER TUBE/DRIVE PLATE ASY
• 2700 TUBE ASY—OUTER (FINAL)
• 2564 SCREW—GEAR/TUBE/PLATE ASY ATT.
• 2467 CAP—OUTER TUBE CLOSURE
• 2633 NYLON SHEET
• 2523 SCREW—NYLON SHEET ATT.
• 2722 BEARING—ROLLER
• 2772 PIN—ROLLER
• 2777 SPACER—CENTER
• 2776 SPACER—OUTER
• 2753 CIRCLIP—RETAINER PIN
• 2325 PLATE ASY—MAIN SCREW DRIVE—FIG. 5
• 2524 PLATE—BALL NUT MOUNT
• 2301 SCREW—MAIN DRIVE
• 2302 NUT—MAIN SCREW DRIVE
• 2303 SCREW—SET MAIN SCREW
• 2654 PIN—DOWEL ROLLER
• 2622 BEARING—ROLLER
• 2406 NUT—PLATE STOP
• 2400 MOTOR/PLATE/GEAR ASY—DRIVE—FIG. 7
• 2413 MOTOR ASY—DRIVE
• 2475 GEAR—PINION MOTOR MOUNT
• 2408 PLATE—MOTOR MOUNT
• 2410 SCREW—MOTOR/PLATE ATT.
• 2412 SCREW—SET GEAR ATT
• 2401 GEAR BOX/TUBE/DRIVE ASY—FIG. 6
• 2514 GEAR WHEEL TRANSMISSION
• 2520 HOUSING—GEAR BOX
• 2521 SCREW—GEAR BOX ATT.
• 2517 BEARING—NEEDLE
• 2773 CAP—BEARING STOP
• 2526 inner tube/drive plate assy
• 2474 PLATE ASY—GEAR SHAFT MOUNT—FIG. 8
• 2471 PLATE—TUBE OUTER
• 2245 PIN—DOWEL GEAR SHAFT
• 2522 BEARING—TRUST
• 2573 SWITCH—LIMIT (UP STOP)
• 2472 SCREW—SWITCH ATT.
• 2500 GEAR/PLATE ASY—MAIN DRIVE SHAFT—FIG. 9
• 2474 PLATE ASY—GEAR SHAFT MOUNT
• 2325 PLATE ASY—MAIN SCREW DRIVE
• 2470 GEAR—WHEEL
• 2518 PIN—DOWEL GEAR LOCK
• 2526 INNER/TUBE DRIVE PLATE ASY—FIG. 10
• 2675 TUBE ASY—INNER (FINAL)
• 2677 SCREW—GEAR/PLA/TUBE ATT
• 2600 TUBE ASY—INNER (WELD)—FIG. 11
• 2625 TUBE—INNER
• 2626 PLATE—INNER SUPPORT
• 2627 PLATE—OUTER SUPPORT
• 2634 TUBE ASY—REAR REINF (WELD)
• 2634 tube assembly—rear reinforcement (welded)—FIG. 12
• 2635 TUBE—REAR REINFORCEMENT
• 2636 NUT—WELD BRACE SUPPORT ATT
• 2675 TUBE ASY—INNER (FINAL)—FIG. 13
• 2600 TUBE ASY—INNER (WELD)
• 2632 SOCKET—TAILGATE PIVOT RH
• 2649 SOCKET—TAILGATE PIVOT LH
• 2549 BUMPER & SCREW ASY—ALIGNMENT
• 2679 PLUG RC COVER—REAR REINF
• 2647 SCRIBET & SCREW ASY—CABLE ATT
• 2860 NUT—SOCKET ATTACHMENT
• 2700 TUBE ASY—OUTER (FINAL)—FIG. 14
• 2268 LATCH—UPPER LOCK
• 2269 SCREW—LATCH ATT
• 2648 BUMPER OVERSLAM/SCREW
• 2828 STRICKER ASY
• 2272 NUT—STRICKER ATT
• 2751 J-NUT—FLOOR ATT
• 2701 TUBE ASY—OUTER (WELD)
• 2701 TUBE ASY—OUTER (WELD)—FIG. 15
• 2738 TUBE—OUTER
• 2272 PANEL ASY—SIDE COLLAR ATT
• 2242 BRACKET—FLOOR SUPPORT
• 2771 BRACKET—STRICKER SUPPORT
• 2733 PANEL ASY—SIDE (WELD)—FIG. 16
• 2740 PANEL—SIDE
• 2741 REINF—SIDE PANEL
• 2270 NUT—WELD M—10×1.5

OVERVIEW

FIG. 18 is a side view of an EPLM device 100 with a tailgate in a lowered position. FIG. 17 is a side view of an EPLM device with a tailgate in a raised position. FIG. 20 is a rear perspective view of a right side assembly of an EPLM device with a tailgate in a lowered position. FIG. 19 is a rear perspective view of a right side assembly of an EPLM device with a tailgate in a raised position. In this example, an EPLM device 100 is attached to the rear portion of a pickup truck 60. The EPLM device has a right side inner/outer tube assembly 2300a, a left side inner/outer tube assembly, and a floor panel 2260. In this embodiment, electric motors are provided in each side assembly, and the motors raise and lower an inner tube/drive plate assembly 2526. The vehicle tailgate is attached to the drive plate assembly so that the tailgate, and a load place on the tailgate, is raised or lowered as the drive plate assembly is raised and lowered.

Each side inner/outer tube assembly includes an side panel assembly 2733 which extends the inner/outer tube assembly past the bumper, and permits the lifting elements and tailgate to move without obstruction from the rear bumper 70. The EPLM device raises or lowers the tailgate 80.

The vehicle tailgate attaches to the side assemblies in the same manner that it attaches to the truck. In this embodiment, the EPLM device is operated from the vehicles electric system, and the electrical connections are made at a single connector provided by the vehicles rear bumper or hitch. The side assemblies are easily removed, so that the truck may be operated in either its standard configuration or with the EPLM device installed.

FIG. 1 is an exploded side perspective view of a right side inner/outer tube assembly 2300a; a left side inner/outer tube assembly; and a floor panel 2260.

Side Assembly and Tailgate Mounting

The side assemblies are mounted over the existing tailgate pivot 95 and upper cable anchor pin 96 so that the side assembly pivot mounting notch 101 in the side panel assembly 2733 is positioned over the tailgate pivot, and the side assembly striker mounting slot 102 is mounted over the cable anchor pin.

A new tailgate pivot 104 and new tailgate striker 105 are provided on the inner tube drive plate assembly 2526 so that the tailgate may be opened and closed with respect to the side assemblies in the same manner that it is opened and closed with respect to the cargo box.

As shown in FIG. 1, the floor panel 2260 and brace 2261 may be quickly installed with four screws 2262 and 2544. When installed, the floor panel acts to secure the side assemblies in a mounted position over the tailgate pivot and upper cable anchor pin.

FIG. 3A is a side view of a side panel assembly 2733. FIG. 3B is a front view of the side panel assembly. FIG. 3C is an isometric view of the side panel assembly.

FIG. 8A is a side view of an inner tube and lift plate assembly 2600. In this example, welded components of the inner tube and lift plate assembly comprise an inner tube 2625, an inner plate support 2626, an outer plate support 2627, and a tube-rear reinforcement 2635. FIG. 8B is a front view of the inner tube assembly of the embodiment of FIG. 8A. FIG. 8C is an isometric view of the inner tube assembly of the embodiment of FIG. 8A.

FIG. 4 is an exploded side perspective view of a right side inner tube drive plate assembly 2526 and the outer tube 2700. In this example, the inner tube drive plate assembly 2526 comprises a nylon sheet 2633 with attachment screw 2523; an outer tube closure cap 2467; a roller bearing 2722; a roller pin 2772; center spacer 2777; outer spacer 2776; and retainer pin 2753.

FIG. 14A is a side view of the outer tube assembly 2700 of the embodiment of FIG. 1. FIG. 14B is a top view of the outer tube assembly of the embodiment of FIG. 14A. FIG. 14C is a front view of the outer tube assembly of the embodiment of FIG. 14A. FIG. 14D is an isometric view of the outer tube assembly of the embodiment of FIG. 14A.

FIG. 15A is a side view of the outer tube 2738 assembly and floor support bracket 2742 of the embodiment of FIG. 1. FIG. 15B is a top view of the outer tube assembly and floor support bracket of the embodiment of FIG. 15A. FIG. 15C is a front view of the outer tube assembly and floor support bracket of the embodiment of FIG. 15A. FIG. 15D is an isometric view of the outer tube assembly and floor support bracket of the embodiment of FIG. 15A.

Motor and Gear Assembly

FIG. 22A is rear view of the right side assembly of FIG. 19 with a motor and gear assembly.

FIG. 22B is cross section view of the right side assembly of FIG. 16 with a motor and gear assembly which shows the outer tube 2738, the inner tube 2625, with the motor mounted with respect to the outer tube.

A gear and motor mounting plate 2410 supports an electric motor and a gear assembly. The electric motor and gears turn a threaded shaft which raises and lowers the inner tube and tailgate support with respect to the inner tube.

FIG. 6 is an exploded view of a motor/plate/gear drive assembly 2400 of the embodiment of FIG. 1. FIG. 7 is an exploded view of the plate and gear assembly 2325 of FIG. 6. The motor/plate/gear assembly drive 2400 comprise a drive motor assembly 2413, a gear-pinion motor mount, and a motor mount plate 2408. The gear box/tube/drive assembly 2401 comprises a gear wheel transmission 2514, a gear box housing 2520, a gear box attachment screw, a needle bearing 2517, and a bearing stop cap 2773. The gear plate assembly 2500 of the main drive shaft 2500 includes a gear shaft mount plate assembly 2474, a main screw drive plate assembly, a wheel gear 2470 and a dowel gear lock.

FIG. 5 is an exploded view of a top portion of the main screw drive plate assembly 2325 which comprises a ball nut mount plate 2524, a main drive screw 2301 with main screw drive nut 2302 and set screw 2303, a dowel roller pin 2654, a roller bearing 2622, and a stop plate nut 2406.

Electrical Components

FIG. 2 is an electrical schematic 2000 of one embodiment of the current invention.

The following review is a functional description of electrical components and wire harnesses and how they are utilized, installed, attached and harness connected into the example tailgate assembly.

Switch-Limit Up-Stop 2573:

This switch is used to shut down the electrical system when the tailgate reaches the up horizontal load position. The switches, two required, are connected via the left/right wire harnesses to the PCB unit and pre-assembled. (See Plate assembly-Gear Shaft Mount 2474 for attachment.)

Switch-Up/Down Control 2474:

This switch controls the up and down tailgate load movement by an operator. When the tailgate reaches the up position, the system is automatically stopped as noted above and the switch reverts to the off position. The operator controls the down movement to a desired load level. A lower stop mechanism attached to the drive screw shaft 2325 is controls the lowest tailgate position. If this occurs the operator shuts down the system. The Switch, one required, is located on the outer side of the left side assembly 2701 and is pre-assembled to the left side harness assembly to communicate to the PCB unit. No remote control is required.

Switch-Tailgate Horizontal Load Position 2861:

This plunger switch indicates to the PCB unit that the tailgate is in the horizontal load open position prior to operating the tailgate downward movement. If the tailgate is in the upper closed lock position, the system will not function. The switch, one required, is pre-assembled to the left side harness assembly and nut attached to the left side tube assembly striker bracket 2771.

Tail Light-LED Stop/Turn/Tail Light 2860:

The light assembly wire attachment is not included in the wire harness assembles. The lighting system wire is attached to the wire harness as shown in attached sketch. A separate wire is required in the left and right wire harnesses to provide its connection to the vehicle's 12-voltage electrical system. The lighting system is independent of the PCB control system. This wire connect is similar to the current trailer vehicle connection. The final light assembly screw attachment to the outer tube is as shown 2000.

PCB Control Unit 2858:

The PCB Unit is utilized to monitor/control an Igarashi Motor/Encoder (Sensor) Assembly 2413 sequence parallel movement of the tailgate. The PCB unit is also monitors the three (3) switch functions as noted above. The unit, one required, shall require a self contained cover which shall be located in the space provided in the inner side of the left side tailgate assembly. The PCB unit is typically included in the lift side wire harness assembly.

Harness Asy-RH:

The limit switch, motor/encoder and LED tail light are socket attached during harness installation process. The harness assembly lower floor attachment is fastened by a series of Xmas clips. The harness is socket connected to the left side harness assembly and attached to the floor pan during the customer installation of the tailgate lift assembly.

Harness Asy-LH 2857:

The left side harness assembly comprise the above components where noted with the motor, limit switch and LED tail light connected in the same manner as the right side. The lower attachment is the same as the right side with a socket connect to the right side harness. A socket lead from the harness to the vehicle's 12-volt trailer hitch system is required.

Installation

In one example, the end customer receives the Tailgate assembly in three (3) containers, one for each side assembly and one for the floor pan with fasteners. The customer installs the tailgate assemblies as follows. No modification to the truck cargo box 85 is required:

• • Inspect if all components are enclosed in the boxes and read the installation instructions.
  • Disconnect the two (2) tailgate cables from the cargo box and remove the tailgate. No tools are required.
  • Insert each side assembly's lower collar into the cargo box tailgate pivot pins and pivot to the vertical position at the cargo box striker pins. Secure the lock latch 2268 to the striker pins via two (2) nuts 2272 on each side.
  • Install the floor pan and secure to the lower support bracket 2261 via two (2) screws 2544.
  • Connect the right side wire harness assembly to the left side wire harness assembly and secure to the floor pan clips.
  • Insert the total wire harness assembly to the truck trailer electrical receptacle for the systems 12-volt system.
  • Install the tailgate to the side assemblies, attach the cables on each side and check closed lock and open load positions.
  • Inspect the lift system's operational performance prior to usage.
  • Disengage the tailgate support cables from the top end and remove the tailgate.
  • Install each side assembly by first inserting the lower side assembly collar system into the truck cargo box tailgate pivot pin and pivot into the vertical position until the side assembly contacts the cargo.

FIG. 12 is a rear perspective view of an EPLM device 100 with a tailgate 80 in a lowered position. (This is a test device which includes a testing support stand).

It is to be understood that the specific embodiments and examples described above are by way of illustration, and not limitation. Various modifications may be made by one of ordinary skill, and the scope of the invention is as defined in the appended claims.