JPS5733261A - Pressure controller for hydraulic circuit - Google Patents

Abstract

PURPOSE: To stabilize the pressure control characteristics by controlling the displacement of a hydraulic pump in respect to an instruction value obtained through a multiplication of a displacement instructing value by an increment value which is in inverse proportion to a pressure controlling gain and is given by arithmetic operation with reference to an engine speed instructing value.

CONSTITUTION: The manipulated variable signal XL of a manipulating lever 15, a pressure signal P and an output speed signal ω are read in, and an increment value ΔX₁ of tilt angle of a swash plate, which is stored in a function generator 24, is referred to as a temporary increment value with respect to the pressure signal P. Further, a reciprocal number ω^-1 stored in the function generator 26 is referred to with respect to the output speed signal ω. Arithmetic operation is made to obtain an increment value ΔX₂ of tilt angle of the swash plate which is a multiplication of the increment value X₁ by the reciprocal number ω^-1 and to obtain a variation Z between the manipulated variable signal XL and the instructing signal X of tilt angle of the swash plate which is outputted in the preceding cycle. The variation Z is then fed to a tilt angle control circuit 20 of the swash plate for controlling a displacement control mechanism 2a.

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