Power plants – Pressure fluid source and motor – Pulsator
Patent
1980-05-23
1982-08-10
Hershkovitz, Abraham
Power plants
Pressure fluid source and motor
Pulsator
60413, 91517, B60T 1126
Patent
active
043431550
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The invention relates to hydraulic circuits for maintaining a fluid level in an element of the circuit. More particularly, the invention relates to initiating a pressure differential through fluid pathways and across the element to maintain the fluid level.
2. Background Art
In hydraulic circuits leakage of the hydraulic fluid can be a problem, particularly when desired fluid levels must be maintained to insure proper and effective operation of work elements which depend upon a fluid supply contained in some type of accumulator, master cylinder or the like. For example, brake systems commonly have a master cylinder which has a reservoir containing a fluid supply for the closed circuit brake system. Optimum operation of the associated brakes requires that the fluid level in the master cylinder reservoir be maintained at a sufficient level to supply fluid throughout the hydraulic lines and other components as operation of the system expands or contracts the fluid volume of the system.
Leakage in the master cylinder or at other locations in the brake system is difficult to eliminate completely owing to the numerous components and connections between the components in the hydraulic circuits associated with such brake systems. Also, work vehicles which contain such brake systems sometimes are operated under harsh conditions which create vibration or can damage the brake system components and tend to promote leakage.
Under such conditions it may be desirable to draw supplemental fluid into the master cylinder reservoir to maintain the fluid level. A syphon or ejector device for supplementing fluid to cool brakes is shown in U.S. Pat. No. 3,101,815 which issued to J. W. Thompson et al on Aug. 27, 1963. Similar devices, utilized for other purposes, are also shown in U.S. Pat. No. 3,358,442 which issued to J. R. Cryder on Dec. 19, 1967, U.S. Pat. No. 3,713,295 which issued to Haak et al on Jan. 30, 1973, and U.S. Pat. No. 3,877,224 which issued to Johnson on Apr. 15, 1975.
Where supplemental fluid is provided to, for example, the master cylinder reservoir, the flow must be sufficient to maintain the level against reasonable leakage in the brake system. However, overfill can also create problems and, therefore, any supplemental fluid supply system preferably will be flexible enough to operate effectively under the potentially wide differences in leakage from brake system to brake system or in one brake system itself.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF INVENTION
In one aspect of the present invention, a hydraulic circuit has a pressurized fluid source and a first fluid pathway in fluid communication with the fluid source and positionable in fluid communication with a second fluid pathway and a first work element. First means initiates a first pressure condition in a third fluid pathway. Second means initiates a second pressure condition in a fourth fluid pathway. A second work element is positioned in fluid communication with the third and fourth fluid pathways. A preselected fluid level in the second work element is maintained in response to a fluid flow initiated by the pressure conditions in the third and fourth fluid pathways.
The preselected fluid level represents, for example, the proper fluid level in a master cylinder reservoir of a brake system. By creating pressure conditions in fluid pathways which communicate with the master cylinder, a fluid flow is induced at a desired magnitude across its reservoir. The fluid is supplied from the first fluid pathway, which is used to pass fluid from the fluid source to the first work element, such as a hydraulic cylinder of an associated vehicle. The flow thus created is used to maintain the fluid level against leakage in the brake system to substantially overcome problems related thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of one embodiment of the present invention showing a hydraulic circuit having venturis positioned be
REFERENCES:
patent: 2820343 (1958-01-01), Berthiez
patent: 3137369 (1964-06-01), Stromberg
patent: 3713295 (1971-04-01), Haak
patent: 3877224 (1973-12-01), Johnson
patent: 4070858 (1978-01-01), Hand
patent: 4174018 (1979-11-01), Liebert
patent: 4215720 (1980-08-01), Becker
Caterpillar Tractor Co.
Heming William B.
Hershkovitz Abraham
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