Differential lock control system for articulated work vehicle

Details Differential lock control system for articulated work vehicle Differential lock control system for articulated work vehicle

1999-10-05

2001-01-16

Marmor, Charles A. (Department: 3681)

Planetary gear transmission systems or components

Fluid drive or control of planetary gearing

Control of differential planetary gearing

C180S235000

Reexamination Certificate

active

06174255

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is directed to an automatic differential lock which is actuated when the wheels on one side of the differential slip in relation to wheels on the other side of the differential more than a programmed amount.
2. Description of the Prior Art
Off road vehicles may be provided with differentials that can be selectively locked and unlocked. Typically the differential lock is controlled by a solenoid operated differential lock control valve that is controlled by a single manually operated foot pedal. To actuate the differential lock the operator must continually depress the foot pedal. Because the differential lock may interfere with steering the differential lock may be disengaged when the vehicle is steered either by application of left or right brakes, or the steering system itself. See U.S. Pat. Nos. 4,523,494 and 4,570,509.
In another differential lock control system, the left and right brakes and the speed of the vehicle can disengage an applied differential lock. The differential lock can be reengaged in response to signals from a steering sensor, a wheel slippage sensor and a draft load sensor. See U.S. Pat. No. 4,549,448.
SUMMARY OF THE INVENTION
An articulated four wheel drive work vehicle is provided with a front assembly having a front axle and left and right front wheels, and a rear assembly having a rear axle and left and right rear wheels. The front assembly and the rear assembly are pivotally coupled to one another by an vertical articulation joint. The front axle is provided with a front differential having a hydraulically actuated front differential lock. The rear axle is provided with a rear differential having a hydraulically actuated rear differential lock. The axles are driven by a transmission having a front mechanical output and a rear mechanical output that are operatively coupled to receiving mechanical inputs on the front and rear differentials.
The front and rear differential locks are coupled to a differential control valve having a front solenoid control valve for directing pressurized hydraulic fluid to the front differential lock and a rear solenoid control valve for directing pressurized hydraulic fluid to the rear differential lock. The solenoid control valves are electrically coupled to a microprocessor which can independently activate the front and rear solenoid control valves. The microprocessor is electrically coupled to a transmission speed sensor located on the transmission, a front axle speed sensor located on the front axle, and a rear axle speed sensor located on the rear axle. The transmission speed sensor senses the output speed of the transmission. The front and rear axle sensors measure the speed of either the left or right axles on either side of the respective differential. The microprocessor is programmed to calculate a predicted axle speed based on the transmission output speed signal from the transmission speed sensor. The microprocessor then compares the predicted output speed to the actual front axle speed signal from the front axle speed sensor. If the actual front axle speed signal differs from the predicted speed more than a programmed amount the microprocessor applies the front differential lock. The same is true for the rear differential lock. The microprocessor compares the predicted output speed to the actual rear axle speed signal from rear axle speed sensor. If the actual rear axle speed signal differs from the predicted speed more than a programmed amount the microprocessor applies the rear differential lock.
An articulation angle sensor senses how much the front assembly and the rear assembly are articulated relative to one another. This sensor sends an articulation angle signal to the microprocessor. If the articulation is greater than a programmed amount the solenoid locks are released.
A two position MAN/AUTO switch is also coupled to the microprocessor and directs the microprocessor to either work in the manual mode or the automatic mode. If the switch is in the manual position both differential locks are manually applied by the operator depressing a foot pedal switch in the cab of the vehicle.


REFERENCES:
patent: 4062420 (1977-12-01), Stedman
patent: 4070924 (1978-01-01), Moreno et al.
patent: 4113044 (1978-09-01), Williams et al.
patent: 4320813 (1982-03-01), Manna
patent: 4523494 (1985-06-01), Sparks et al.
patent: 4549448 (1985-10-01), Kittle
patent: 4559847 (1985-12-01), Newendorp et al.
patent: 4570509 (1986-02-01), Nighswonger
patent: 4895217 (1990-01-01), Hueckler et al.
patent: 5505267 (1996-04-01), Orbach et al.
patent: 5535124 (1996-07-01), Hosseini et al.
patent: 5927422 (1999-07-01), Schakel
patent: 6009969 (2000-01-01), Salcher et al.
John Deere brochure entitled “Loaders 544G 624G 644G”, pp. 1-22, printed in the U.S., 1996.
John Deere brochure entitled “Loaders 444H 544H”, pp. 1-20, printed in the U.S, 1999.

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