Motors: expansible chamber type – Plural relatively movable or rigidly interconnected working... – Condition responsive means for modifying working member...
Patent
1980-06-02
1982-08-24
Hershkovitz, Abraham
Motors: expansible chamber type
Plural relatively movable or rigidly interconnected working...
Condition responsive means for modifying working member...
91517, F15B 1120
Patent
active
043455085
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
This invention relates generally to a control system and more particularly to a transmission control system which prevents the engagement of a fluid actuated clutch until one of a pair of fluid actuated clutches has been engaged.
BACKGROUND ART
Some hydraulic controls for power shift transmissions automatically provide for the sequential engagement of specific clutches after the transmission is shifted from one speed to another. For example, the system disclosed in U.S. Pat. No. 3,091,976 which issued to Johnson et al. on June 4, 1963 causes the speed clutches to be fully engaged before either one of the directional clutches is engaged so that the directional clutches absorb the shock of transmitting power through the transmission. With that system both the selector valve and directional control valve are directly controlled by the operator through a mechanical linkage. However, the control system of many of the industrial vehicles are being designed to incorporate pilot control circuits to control the shifting of the main control valves. Those pilot control circuits can be either totally hydraulic or a combination of electrical and hydraulic components. In either case, while the sequential engagement system taught by the above-noted patent has functioned satisfactory in the direct operator controlled arrangement in which it is used, that specific system is not readily convertible to a pilot operated control circuit.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
In one aspect of the present invention a control system adapted for sequentially actuating first, second and third fluid actuators has a pump and a drain line connected to a tank, a supply line connected to the pump, and a selector valve connected to the supply line and to the first and second fluid actuators. The selector valve is movable between a first position at which the supply line is communicated with the first fluid actuator and a second position at which the supply line is communicated with the second fluid actuator. A fluid actuated valve is connected to the supply line, the drain line and the third fluid actuator and has a valve element movable between a first position at which the third fluid actuator is communicated with the drain line and a second position at which the supply line is communicated with the third fluid actuator, a spring biasing the valve element to the first position, and a fluid chamber at one end of the valve element. The valve element is moved to the second position in response to fluid pressure in the fluid chamber exceeding a preselected value and to the first position in response to the fluid pressure in the fluid chamber dropping below the preselected value. A means is provided for dumping the fluid in the fluid chamber of the fluid actuated valve to the drain line for dropping the fluid pressure in the fluid chamber below the preselected value responsive to shifting the selector valve between the first and second positions. An orifice connecting the supply line to the fluid chamber delays the filling of the fluid chamber with fluid until the selected one of the first and second fluid actuators is filled with fluid.
The control system of the present invention provides a system in which one of a pair of fluid actuated clutches is engaged prior to engagement of a third fluid actuated clutch so that the third clutch always absorbs the shock of transmitting power through the transmission when the transmission is shifted. The valves utilized to control the engagement and disengagement of the fluid actuated clutches are fluid actuated valves and are controlled by directing pressurized fluid thereto from the control system by selectively operable valves. The components of the system causing the selected one of the pair of clutches to be engaged prior to the engagement of the third clutch utilizes the characteristic of many power shift transmissions wherein the fluid pressure in the control system drops drastically due
REFERENCES:
patent: 2713246 (1955-07-01), Dall
patent: 3217726 (1965-11-01), Rohweder
patent: 3349670 (1967-10-01), Bahl
patent: 3490338 (1970-01-01), Faust
patent: 3934742 (1976-01-01), Tennis
patent: 3944035 (1976-03-01), McRay
patent: 3967534 (1976-07-01), Cryder
patent: 3990237 (1976-11-01), Van Gerpen
patent: 3998111 (1976-12-01), Blake
patent: 4024797 (1977-05-01), Johnson
patent: 4070858 (1978-01-01), Hand
Caterpillar Tractor Co.
Grant John W.
Hershkovitz Abraham
LandOfFree
Control system for sequentially actuating fluid actuators does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Control system for sequentially actuating fluid actuators, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Control system for sequentially actuating fluid actuators will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1432469