Power plants – Pressure fluid source and motor – Expansible chamber type volumetric responsive measuring...
Patent
1996-09-27
1998-06-30
Lopez, F. Daniel
Power plants
Pressure fluid source and motor
Expansible chamber type volumetric responsive measuring...
60387, F16D 3102
Patent
active
057716927
DESCRIPTION:
BRIEF SUMMARY
A steering device is described in the British Printed Patent Document GB-A-2014096, which steering device does not exhibit this disadvantage. For this purpose, this steering device is furnished with an auxiliary, secondary line, which branches off from the main line downstream of the adjustable input throttle and which leads through a load-signal throttle to the discharge connector. In addition, two adjustable throttles are disposed in parallel arrangement in this auxiliary, secondary line. The two throttles are closed in the neutral position, and the two throttles are opened with the adjustable input throttle in the same direction. One of the two throttles closes in case of a certain deflection angle, whereas the second throttle remains opened. Since the two throttles are operating synchronously over the complete deflection region, the opening characteristics of the two throttles have to be precisely coordinated to each other. These production requirements are therefore very high and associated with substantial cost and cannot be realized under the conditions of series production such that it leads to an undefinable steering behavior of the individual steering devices. Such behavior is not acceptable in connection with these devices.
The invention relates to a hydraulic steering device employed in mobile plants, which include a steering circuit and a work circuit and where both the steering circuit and the work circuit are supplied by a common pump, wherein the steering circuit is furnished with priority.
Such plants comprise mainly a common supply pump and a flow divider valve, as well as a steering device and a steering cylinder on the one hand and a work circuit on the other hand. The flow divider valve is provided as a spring-loaded valve and receives its control signal as a so-called load signal from the hydraulic steering device. According to this load signal, the flow divider valve automatically controls its passage flow cross-sections in such a way that the steering circuit is supplied with precedence and according to need and that the work circuit is supplied with the excessive compression oil. It is known to condition the load signal statically or dynamically. Based on the high reaction capability of a dynamic load signal, this kind of conditioning predominates more and more in practice.
For example, a steering device with the dynamic load signal is known from the European Patent 0 096 963. This steering device is furnished with a load-signal path, which branches off from the main current flow line from the steering device and is led, on the one hand, to the spring-loaded side of the flow divider valve and, on the other hand, to a separate connection of the steering device; wherein the load-signal path joins again to the main current flow line within the steering device after the first adjustable throttle, and leads from there simultaneously to the return line. In the part of the load-signal path, leading to the return line, there is disposed an adjustment throttle, operating proportional inversely to the first adjustable throttle and actuatable by the steering device. This steering device is associated with the disadvantage that, even in case of high steering speeds and thus high flow volumes, there is required an automatic control spring with a relatively high spring stiffness level for maintaining a preferred and required supply of the steering aggregate. One always has to work against this strong automatic control spring in the neutral position, i.e. in case of a non-actuated steering device, in order to supply the work circuit. This requires high energy losses and high power losses of the hydraulic plant.
It is the object to raise the load-signal pressure level to meet the requirement in connection with steering devices of the recited kind.
The steering device according to the invention contributes to the improvement of the energy balance of the hydraulic plants of this kind. The application of a weaker, the load-signal-supporting pressure spring becomes possible with the increase, meeting
REFERENCES:
patent: Re25126 (1962-02-01), Charison
patent: 4096883 (1978-06-01), Yip
patent: 4665695 (1987-05-01), Rau et al.
patent: 4759182 (1988-07-01), Haarstad
patent: 4838314 (1989-06-01), Gage
Bergmann Erhard
Schildmann Manfred
Voss Gerhard
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