JPS6124225B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle drive system, and more particularly to a fluid drive system for steering a tracked vehicle.

When using tracked vehicles, it is of course important to be able to drive the vehicle effectively in a straight line. Furthermore, it is clear that the vehicle must also be effectively steered in either the forward or reverse direction of vehicle operation. It is generally known to provide two separate hydraulic motor arrangements to drive the wheels or tracks on each side of a vehicle. Such a device is disclosed in US Pat. No. 3,655,004. It will be appreciated that it would be advantageous to provide such a device in which a single pump could be used to provide suitable drive and actuation operations for steering vehicle wheels or tracks.

U.S. Pat. No. 2,560,554 discloses a drive device in which a plurality of shafts can be locked together relative to each other for driving a vehicle via a planetary gear drive. Also, such shafts can be rotated in opposite directions to obtain a steering effect.

It will be appreciated that the above-mentioned patent uses relatively complex electrical and mechanical devices to effect steering of such vehicles.

US Pat. No. 3,672,167 discloses a hydraulic transmission and a motor used to drive a differential for driving a pair of wheels.
However, no steering device is disclosed in that specification.

U.S. Pat. No. 3,782,488 discloses a pair of hydraulic transmissions with a single control device for controlling the displacement of a pair of pumps to obtain steering action. Thus, as in US Pat. No. 3,655,002, a pair of pumps is used to operate the drive and steering device.

SUMMARY OF THE INVENTION Accordingly, one object of the present invention is to provide a tracked vehicle drive and steering system that uses a fluid motor to drive and steer a tracked vehicle.

A further object of the invention is to provide a device which achieves the above objects and which is extremely simple in design and effective to use.

Generally speaking, the present invention includes a first motor and an apparatus for operatively coupling the first motor and the track to drive the track of a vehicle.
Includes a vehicle drive and steering system with a pair of tracks. Additionally, the invention includes a second motor that is a fluid motor. Additionally, the present invention includes an apparatus for selectively supplying pressurized fluid to the second motor to selectively drive the second motor. Additionally, the present invention includes a second motor and at least one of the tracks to provide a relative differential motion between the tracks that is different from the relative differential motion provided by the first motor. Apparatus is included for coupling the and in operative relationship.

These and other objects of the invention will be clearly understood from the following specification and the accompanying drawings, which show schematic illustrations of a vehicle drive and steering system according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the accompanying drawings, there is shown generally a device 10 for driving and steering a tracked vehicle having drive sprockets indicated by reference numerals 12 and 14. As shown, the vehicle's engine 15 drives a pump 16 through a gear train 18 . Pump 16 draws fluid from reservoir 20 and directs the fluid through line 21 and filter 22 to ventilate 24 and from ventilate 24 to orifice 26 and then to vehicle hydraulic control system 28. The engine 15 also drives a reversible variable displacement hydraulic pump 30. Pump 30 is connected to a variable displacement hydraulic motor 32 by conduits 34 and 36. The variable displacement pump 30 is of a known type and is connected to the hydraulic control device 2 by means of a conduit device 38.
8, thereby operating hydraulic control device 28 in a selected manner to vary the displacement of pump 30 and, in turn, drive motor 32 in a selected manner.

Output shaft 40 of motor 32 drives gear 42, which in turn engages gear 44 to drive shaft 46. The opposite ends of the shaft 46 are operatively associated with planetary gear sets 48, 50 of the same type, connecting them to respective sprockets 12, 14 of the vehicle. Therefore, only one planetary gear set 48 and its connection with the end of the shaft 46 will be described in detail below.

A gear 52 is fixed to the end of the shaft 46 on the planetary gear set 48 side, and the gear 52 engages with a plurality of sun gears 54 rotatably mounted on the intermediate member 56. . Intermediate member 56
An outwardly extending shaft 58 is secured to the. A gear 60 is fixed to the shaft 58. Gear 60 engages gear 62 to drive gear 62 which is secured to shaft 64 of sprocket 12. The plurality of gears 54 also include the ring gear 6
It is engaged with 6. Ring gear 66 has outwardly projecting teeth 68. Tooth 6 of ring gear 66
8 is in a pair of gears 70 and 72 which are fixed together by a shaft 74, and engages with the teeth of gear 70. The other gear 72 of the pair of gears is engaged with a gear 76 fixed to a shaft 78.
A bevel gear 80 is fixed to the opposite end of the shaft 78. As mentioned above, planetary gear set 50 is identical in type to planetary gear set 48 and is associated with sprocket 14.

A relief and replenishment valve 82 as generally disclosed in U.S. Pat. No. 3,477,225 is provided in conduit 84,
It is operatively associated with pump 30 and motor 32 by 86, 88 and 90. Relief and refill valve 82 runs from line 21 to line 9
2 to the low pressure side of the conduits 34, 36, and the conduits 34, 36
Additional fluid from the low pressure side conduit in the valve can be aspirated to provide fluid from the relief and replenishment valve 82 into the conduit 94 under the conditions described below.

Conduit 94 communicates with a two-position valve 96, which in turn communicates with a reversible motor 98 via conduits 100 and 102. A bevel gear 106 is fixed to the output drive shaft 104 of the motor 98 . The bevel gear 106 engages the bevel gears 80, 80' thereby causing the bevel gears 80, 80', 106
constitutes a differential gear 108. A conduit 110 extends from the two-position valve 96 to a variable pressure compensated meter flow control valve 112. The flow control valve 112 is not sensitive to vehicle loads which determine the pressure in the drive and can be opened and closed by the control mechanism described below.
If fluid control valve 112 is in the open position, fluid from relief and replenishment valve 82 flows through motor 98 in one direction and the other direction, driving motor 98 in one direction and the other direction, and causing flow control valve 112 to flow through motor 98 in one direction and the other direction. through conduit 92 and back to relief and replenishment valve 82 .

A pair of pilot valves 114, 116 are provided for directing fluid from conduit 118 toward two-position valve 96 to position the two-position valve 96 in one position and the other. This valve 114 is, for example, a steering valve that is operated by operating a lever (not shown) provided in the driver's cab of the vehicle. Valve 114 always occupies one position or the other to direct fluid toward one side or the other of valve 96. However, it will be appreciated that when flow control valve 112 is closed, no fluid flow through motor 98 and valve 96 can occur. As a result, motor 9
8 is held against rotation, so that no steering action occurs. This lever can be selectively operated to occupy a vertical position, for example, to determine the closed position of the flow control valve 112. When the lever is moved in one direction, the flow control valve 1
12 and moves the steering valve 114 to a selected steering position, or if the steering valve 114 already occupies such a selected position, leaves the steering valve 114 in that position.
If you move this lever from the neutral position in the other direction,
Steering valve 114 moves to the other position and opens orifice 112. Moving the lever back to the neutral position leaves the steering valve 114 in the position it occupied and closes the flow control valve 112.

Valve 116 is connected in series with valve 114 to reverse the overall flow of pilot fluid to valve 96.

Under normal operating conditions, with no steering action, engine 15 drives pump 30, which in turn drives motor 32, which in turn drives shaft 46. Relief and replenishment valve 82 supplies fluid to the low pressure side of conduits 34,36. Since the flow control valve 112 is closed,
Fluid cannot flow from conduit 94 through motor 98. Differential gear 108 is thus constrained in motion and shafts 78, 78' are therefore constrained against rotation. Shaft 46 thus rotates gears 52, 52' and thereby rotates sun gears 54, 54'. Shaft 78,7
8' is not rotating, so ring gears 66, 6
6' are held together so that they do not rotate, so that the sun gears 54, 54' are tied to the ring gears 66, 6'.
6' to drive shafts 58, 58' which in turn drive track drive sprockets 12, 14 at the same speed. As a result, the vehicle can be driven in a straight line. It will be appreciated that reversing the pump 30 drives the motor 32 in the opposite direction, thereby driving the track drive sprockets 12, 14 in the opposite direction at a constant speed.

Assuming that the track drive sprockets 12, 14 are driven at exactly the same speed, and that it is desired to steer the vehicle, the aforementioned lever is operated to open the flow control valve 112, and the steering valve 114 selects the vehicle. If the steering valve 114 is not already in a suitable position for steering onto the street.
can be moved to an appropriate position. For example, assuming steering valve 114 is moved upwardly, pilot fluid is supplied to the right side of valve 96 so that valve 96 assumes the first position as shown. Fluid is then pumped from relief and replenishment valve 82 through conduit 94 and valve 96 to rotate motor 98 in one direction. motor 9
By driving shaft 8 in this way, shaft 7
8, 78' to rotate one of said shafts in one direction and the other in the opposite direction, differential motion is transmitted through planetary gearing 48, 50 to the vehicle's track drive sprocket 12 and 14
As a result, one of such drive sprockets will in fact have a relative speed reduction. As a result, it will be appreciated that steering of the vehicle is accomplished through the differential of the tracks driven by the track drive sprockets 12,14.

By moving steering valve 114 to the other position, pilot fluid is supplied to the other side of valve 96 to move valve 96 to its second position, thereby supplying pressurized fluid to motor 98 . It will be understood that driving in the other direction. Therefore,
Tracks that were previously relatively slowed down are sped up to their normal drive speed, and tracks that were previously driven at their normal drive speed are slowed down.

If the vehicle is being driven in the opposite direction, forward/reverse selector valve 116 is actuated and valve 96
Reverse the direction of pilot fluid flow to the This allows the reversal of the output drive of the motor 98, which is necessary when driving the vehicle in the opposite direction, thereby ensuring that the vehicle is steered to the left or right as selected by operating the lever in the same manner. This makes it possible to steer in one direction.

As described above, in the vehicle track drive and steering device according to the present invention, the fluid that drives the track drive hydraulic motor 32 also drives the differential hydraulic motor 98. , and the differential hydraulic motor 98 is operatively coupled to the hydraulic controller 28 of the track drive hydraulic motor 32. That is, the differential hydraulic motor 98 is driven by the power source, ie, the pressure fluid, of the hydraulic motor 32 that is always available for endless track drive in the normal state, and is controlled by the same control device. A special power source and control device for the differential hydraulic motor 98 is not required.

[Brief explanation of the drawing]

The accompanying drawings are schematic illustrations of a vehicle drive and steering device according to the invention. 10... Track type vehicle drive and steering device, 12, 14... Drive sprocket, 15...
Engine, 16...Pump, 18...Gear train, 2
4... Bench lily, 26... Orifice, 28
... Hydraulic pressure control device, 30 ... Variable displacement hydraulic pump, 32 ... Variable displacement hydraulic motor, 40 ... Output shaft, 42, 44 ... Gear, 46 ... Shaft, 48, 50 ... Planet Gear device, 52... Gear, 54, 54'... Sun gear, 56, 56'...
Intermediate member, 58, 58'... Shaft, 60, 6
0', 62, 62'... Gear, 64, 64'... Shaft, 68, 68'... Teeth, 70, 70', 7
2,72'...gear, 74,74'...shaft,
76, 76'... Gear, 78, 78'... Shaft, 80, 80'... Gear, 82... Relief and replenishment valve, 84, 86, 88, 90, 94...
Conduit, 96... 2 position valve, 98... Reversible fluid motor, 100, 102... Conduit, 104... Shaft, 108... Differential gear, 110... Conduit, 1
12...Flow control valve, 114, 116...Pilot valve.

Claims (1)

Claims: 1. A drive and steering device 10 for a vehicle having a pair of endless tracks 12, 14, comprising: a hydraulic transmission having a hydraulic motor 32 and a hydraulic pump 30; .
and a hydraulic control device 28 coupled to the hydraulic transmission for controlling the hydraulic motor.
a reversible hydraulic motor 98; and fluid passage devices 94, 96 for selectively communicating pressure fluid to the reversible hydraulic motor 98 for selectively driving the reversible hydraulic motor 98, the communication (i) The fluid that drives the hydraulic motor 32 is connected to the reversible hydraulic motor 9.
(ii) is operatively coupled to the hydraulic control device 28; The reversible hydraulic motor 98 and the endless track 12, in order to obtain a relative differential motion between the endless tracks 12, 14 that is different from the relative drive motion between the endless tracks 12, 14 obtained by the
14 in operative relationship.
Vehicle track 1 with 0,104,108
2,14 drive and steering devices. 2. The hydraulic control device 28 is operatively coupled to a pilot pump 16 and a valve 96 operatively coupled to the reversible hydraulic motor 98 for selectively reversing the hydraulic motor 98. A vehicle track drive and steering device according to claim 1.