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Position: Home >> Hydraulic valve mechanism
A hydraulic valve mechanism has a housing with first and second bores, a control valve element in the first bore, a pressure compensation valve in the second bore, and a non-return valve cooperating with motor parts, wherein control edges for direction control are arranged on the control valve element only at one side of throttle means, the non-return valve is also arranged in the second bore of the housing, and the longitudinal valve element of the pressure compensation valve also forms a closing member of the non-return valve.
The present invention relates to hydraulic valve mechanisms.
Hydraulic valves are known and widely utilized.
One hydraulic valve is disclosed in the German Offenlegungsschrift No. 2,252,772, in which the functions of the pressure compensation of a pressure compensation valve are performed by a longitudinal valve element, whereas the functions of the throttle means and the direction control of the pressure medium stream to the motor ports are performed by a control valve element. For the functions of a load-maintaining non-return valve, a non-return valve separate from both the above-mentioned control elements is provided. Such a construction has the disadvantage that, for the above-mentioned four functions, three control elements are provided so that the valve is relatively expensive. In addition, the longitudinal axis of the non-return valve extends normal to the longitudinal axis of the control valve element so that the housing of the valve has a relatively great height. Moreover, in the known valve the control edges for the direction control are formed on the control valve element at both sides of the throttle means, which leads to the fact that downstream of the non-return valve for the pressure medium control to and from the motor ports, altogether six working chambers are necessary. This also increases the space consumption for the control valve. By the arrangement of the control edges for the direction control at both sides of the throttle means, the return chamber associated with the control valve element is arranged so far outwardly that a special return chamber must be provided for unloading of the control pressure medium in the region of the throttle means. Thereby, a compact construction of the valve in longitudinal direction of the control valve element is undesirably affected.
Further, a hydraulic valves is disclosed in the German Offenlegungsschrift No. 1,751,934 which is suitable for load-independent control. In this valve, the control edges for the direction control are arranged at one side of the throttle means on the control valve element; however, the throttle means here cooperate with a pressure compensating valve as bypass-flow control unit. This valve has the disadvantage that it does not have a non-return valve which protects the motor ports. In addition, this valve is poorly suitable for a parallel connection of several such valves.
Accordingly, it is an object of the present invention to provide a hydraulic valve mechanism which avoids the disadvantages of the prior art.
More particularly, it is an object of the present invention to provide a hydraulic valve mechanism which performs the same functions as known valves, but is less expensive than the latter.
In keeping with these objects, and with others which will become apparent hereinafter, one feature of the present invention resides, briefly stated, in a hydraulic valve mechanism having a housing, a control valve element in a first bore, a pressure compensating valve, and a non-return valve, wherein control edges for the direction control arranged on the control valve element are located only at one side of throttle means, the non-return valve is arranged in a second bore in which the pressure compensation valve is arranged, and a longitudinal valve element of the pressure compensation valve also forms a closing member of the non-return valve.
When the hydraulic valve mechanism is designed in accordance with the present invention, the required four functions are performed by only two control elements which not only simplify the construction of the valve mechanism, but also reduces the space consumption. The combination of the non-return valve with the pressure compensation valve in one axis provides for a considerably smaller housing of the valve mechanism. By performing the respective two functions to each valve element axis, the available space can be better utilized. The valve mechanism can be designed with five chambers for the direction control. The valve mechanism is better suited for parallel connection of several identical valve mechanisms.
In accordance with another advantageous feature of the present invention, the control valve element have control edges controlling communication from a chamber located downstream of the throttle means and upstream of the non-return valve, to the return chamber located near the motor chamber. In such a construction for unloading of the control pressure medium and for working pressure medium, the same return chamber can be utilized. This contributes to the compact construction of the valve mechanism.
The novel features which are considered characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawing.
