Vehicle body with powered lift type tailgate

Abstract

A tailgate is hinged to a passenger van type vehicle body above a substantially vertical rear access opening for swinging movement about a horizontal hinge axis. The tailgate is counterbalanced through its range of movement by spring devices and is opened and closed by a powered actuator mounted on a rear vehicle body pillar. The actuator includes a reversible electric motor driving a worm shaft that drives a worm gear to pivot a crankarm about an axis parallel to the hinge axis. A roller mounted on the crankarm is received in a guide channel that is fixed to the tailgate and extends at right angles to the hinge axis with the pivoting movement of the crankarm thereby translated into swinging tailgate opening and closing movement. The motor is connected with torque sensing circuitry that detects an excessive motor torque demand when the tailgate encounters an obstacle and stops the motor. A normally engaged clutch maintains drive connection between the worm gear and the crankarm to effect normal tailgate opening and closing by the motor and slips to allow manually applied force on the tailgate to open and close same when the motor is not operating.

What is claimed is: 
     
       1. In combination, a vehicle body having a rear opening, a tailgate adapted to open and close said rear opening, a hinge pivotally mounting said tailgate on said vehicle body for swinging movement about a horizontal hinge axis located adjacent an upper edge of said tailgate so that said tailgate on upward lifting movement is moveable from a closed position closing said rear opening to an open position completely opening said rear opening, a pair of counterbalance devices operatively connected between said vehicle body and said tailgate substantially counterbalancing the weight of said tailgate as it swings to open and close said rear opening, a singular tailgate actuator mechanism mounted on said vehicle body adjacent said upper edge of said tailgate and operatively connected to said tailgate, said actuator mechanism comprising a reversible electric motor, a crankarm pivotal in an arc transverse to said hinge axis, torque multiplying drive means including a normally engaged clutch operatively connecting said motor to said crankarm, a guide channel mounted on and extending along an inner side of said tailgate transfer to said hinge axis, a roller mounted on said crankarm and received and retained in said guide channel, said guide channel having opposing guide rails engaged by said roller at diametrically opposite locations thereby to effect movement of said tailgate between said closed and open positions by said roller rolling in said guide channel on pivotal movement of said crankarm in opposite directions by said motor, said clutch having a load capacity sufficient to effect normal tailgate opening and closing by said motor and to slip to allow an external force on said tailgate to open and close same independent of motor operation, and a controller controlling said motor that detects an excessive amount of motor torque demand when said tailgate encounters an obstacle during motor powered movement and stops the motor before slippage in the clutch occurs. 
     
     
       2. In combination, a vehicle body having a substantially vertical rear opening, a tailgate adapted to open and close said rear opening, a hinge pivotally mounting said tailgate on said vehicle body for swinging movement about a horizontal hinge axis located adjacent an upper edge of said tailgate so that said tailgate on upward lifting movement is moveable from a closed substantially vertical position closing said rear opening to an open upwardly angled position above horizontal completely opening said rear opening, a pair of gas springs operatively connected between said vehicle body and said tailgate substantially counterbalancing the weight of said tailgate as it swings to open and close said rear opening, a singular tailgate actuator mechanism mounted on said vehicle body adjacent said upper edge of said tailgate and operatively connected to said tailgate, said actuator mechanism comprising a reversible DC constant speed motor, a crankarm pivotal in an arc at right angles to said hinge axis, drive means operatively connecting said crankarm to said motor including a worm shaft connected to be driven by said motor, a worm gear driven by said worm shaft, a torque multiplying gear train operatively connected to pivot said crankarm, a normally engaged clutch connecting said worm gear to said gear train, a guide channel mounted on and extending along an inner side of said tailgate at right angles to said hinge axis, a roller mounted on said crankarm and received and retained in said guide channel, said guide channel having opposing guide rails extending longitudinally at right angles to said hinge axis and extending width wise parallel to said hinge axis and engaged by said roller at diametrically opposite locations thereby to effect movement of said tailgate between said closed and open positions by said roller rolling in said guide channel on pivotal movement of said crankarm in opposite directions by said motor, said clutch having a load capacity sufficient to effect normal tailgate opening and closing by said motor and to slip against the reaction force of said worm shaft to allow an external force on said tailgate to open and close same, and a controller controlling said motor that detects an excessive amount of motor torque demand when said tailgate encounters an obstacle during motor powered movement by sensing motor current load and stops the motor before slippage in the clutch occurs. 
     
     
       3. A combination as set forth in claim 2, and said vehicle body having a rear pillar adjacent said rear opening, said rear pillar having an upper end, and said actuator mechanism except for said guide channel wholly mounted on said rear pillar near said upper end. 
     
     
       4. A combination as set forth in claim 3, and said tailgate having a window and said guide channel mounted between a side edge of said tailgate and said window. .Iadd. 
     
     
       5.  A powered lift tailgate mechanism in combination with a vehicle body and a tailgate comprising: an electric motor drive coupled to said vehicle body;   a gear train system coupled to said motor drive and to said tailgate for transferring mechanical forces from said motor drive to said tailgate to thereby open said tailgate;   a clutch mechanism integrated with said gear train system and operable to permit manual movement of said tailgate through a manually applied force and to inhibit the transfer of said manually applied force to said motor drive;   electronic controller for supplying operating current to said motor drive, said controller including system for electrically sensing torque produced by said motor drive and for automatically inhibiting the supplying of operating current to said motor drive when said torque produced exceeds a first predetermined torque; and   said first predetermined torque required to inhibit a supply of operating current to said motor is slightly greater than an amount of torque required to cause said clutch mechanism to slip. .Iaddend..Iadd.6. A powered life tailgate mechanism as claimed in claim 5, wherein said clutch mechanism further comprises:   a clutch pad mechanically communicating with said motor drive;   a clutch pressure plate mechanically communicating with said tailgate, said clutch pressure plate being adjacent to said clutch pad; and   a clutch spring forcing said clutch pressure plate to engage said clutch pad, said clutch spring maintaining said clutch pressure plate and said clutch pad in a locked condition when said motor drive has a torque output less than a second predetermined amount of torque, said clutch spring allowing said clutch pad and said clutch pressure plate to slip when said motor drive has a torque output greater than said second predetermined amount of torque. .Iaddend..Iadd.7. A powered lift tailgate mechanism as claimed in claim 6, wherein said second predetermined amount of torque is a value greater than an amount of torque required by said motor drive to   
     
     
        move said tailgate. .Iaddend..Iadd.8.  A powered lift tailgate mechanism as claimed in claim 5, wherein said electronic controller further comprises: at least one actuator control circuit, said actuator control circuit being in electrical communication with said motor drive; and   a switch electrically connected to said actuator control circuit, said switch having at least one position, said one position stopping said motor drive from moving said tailgate at any given position of said tailgate. .Iaddend..Iadd.9. A powered lift tailgate mechanism as claimed in claim 5, further comprising at least one gas spring with a first end and a second end, said first end of said gas spring being pivotally connected to a vehicle frame and said second end of said gas spring being pivotally connected to said tailgate, said gas spring being adjusted to counterbalance the weight of said tailgate and minimize the amount of torque of said motor drive required to open and close said tailgate. .Iaddend..Iadd.10. A powered lift tailgate mechanism as claimed in claim 5, wherein said tailgate is hingedly attached to said vehicle body by at least one hinge. .Iaddend..Iadd.11. A powered lift tailgate mechanism as claimed in claim 5, further comprising a latch, said latch having a solenoid operated latching mechanism on a bottom edge of said tailgate and a locking bolt affixed to said vehicle body. .Iaddend.