Control arrangement for at least two hydraulic consumers

Details Control arrangement for at least two hydraulic consumers Control arrangement for at least two hydraulic consumers

1996-11-20

1998-05-19

Lopez, F. Daniel

Power plants

Pressure fluid source and motor

Having condition responsive control in a system of distinct...

60452, 91447, F16D 3102

Patent

active

057523843

DESCRIPTION:

BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION

The present invention is based on a control arrangement or system for at least two hydraulic consumers having a positive displacement pump which is adjusted by a load-sensing regulator responsive to a load-signaling line with the highest load pressure of the plural consumers, on which there are superimposed a maximum-pressure and an output regulation. The system includes two displaceable metering throttles, the first of which is connected between the positive displacement pump and a first hydraulic consumer and the second of which is connected betweeen the positive displacement pump and a second hydraulic consumer. The system further comprises two pressure compensators, the first one of which is connected behind the first metering throttle and the second of which is connected behind the second metering throttle and, wherein, regulating pistons of the compensators are activated on a front side by the pressure behind the corresponding metering throttle in an opening direction and on a rear side of the piston by the pressure in the load-signaling line in the closing direction.
Such a control arrangement is known from EP 0 566 449 A1. It comprises a positive displacement pump which can be so adjusted as to produce at its output a pressure which lies a given amount above the highest load pressure of all hydraulic consumers. A load-sensing regulator is present for this so-called load-sensing regulation which can be acted on by the pump pressure for a reduction of the displacement volume of the positive displacement pump and by the highest load pressure and a compression spring for an increase in the displacement volume of the pump. The difference between the pump pressure and the highest load pressure corresponds to the force of this compression spring.
The pressure compensator which is arranged downstream of each displaceable metering diaphragm maintains the pressure drop over the metering diaphragm constant so that the amount of pressurized fluid flowing to a hydraulic consumer is dependent solely on the opening cross section of the metering diaphragm and not on the load pressure of the consumer or on the pump pressure. At the same time, by means of the pressure compensators, the result is obtained that, in a case in which the hydraulic pump has been displaced up to the maximum displacement volume and the stream of pressurized fluid is not sufficient to maintain the pre-established pressure drop over the metering diaphragms, the pressure compensators of all actuated hydraulic consumers are displaced in closing direction so that all streams of pressurized fluid to the individual loads are reduced by the same percentage. On the basis of this load-independent distribution of flow, all actuated consumers move with a speed which is reduced percentually by the same value.
A load-sensing-regulated variable displacement pump is ordinarily equipped also with a pressure regulation by which the maximum possible pump pressure is pre-established, and with an output regulation which determines the maximum output which can be provided by the pump. Pressure regulation and output regulation are superimposed on the load-sensing regulation.
With a control arrangement of the type described, the following manner of actuation of two hydraulic consumers is now possible. The one hydraulic consumer is moved up to a stop and is to be held against this stop. For instance, a clamp which clamps an object fast between its jaws can be moved by the consumer. After the clamping fast of the object, another hydraulic consumer is actuated in order to move the object from one place to another. The two hydraulic consumers can be present, for instance, on a mobile working machine, in particular an excavator. Upon the clamping fast of the object, a pressure builds up on the corresponding hydraulic consumer, this pressure corresponding to the maximum pressure predetermined by the pressure regulation. Because of this high pressure, the output regulation of the variable displacement pump responds even in the case

REFERENCES:
patent: 4938023 (1990-07-01), Yoshino
patent: 5305789 (1994-04-01), Rivolier
patent: 5347811 (1994-09-01), Hasegawa et al.
patent: 5460000 (1995-10-01), Kropp
N.N.: An Den Bedarf Anpassen In: fluid, Oct. 1988 pp. 18, 23, 24.

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