Dual volume pump

Abstract

The present invention provides a dual-capacity pump capable of carrying out pressure compensation in the dual-capacity pump which may switch the discharge capacity into large capacity or small capacity. The dual-capacity pump comprises: a pump body (12) used for rotatablely driving to suck in or discharge water; a capacity variable mechanism (14) capable of changing discharge capacity of each unit rotation of the pump body (12); a capacity switching valve (16) selectively communicating a high-pressure side flow path and a low-pressure side flow path to a pressure guide path, the pressure guide path may communicate with the capacity variable mechanism (14); and a pressure compensation valve (18) as a pressure compensation mechanism. The dual-capacity pump may switch the discharge capacity into any one of the large capacity and the small capacity with the capacity switching valve (16), further, the pressure compensation valve (18) reduces the discharge capacity of the pump body into less than above capacity by switching act when the discharge pressure of the pump body reaches set pressure.

Description

technical field [0001] The present invention relates to a dual capacity pump which is a variable capacity type pump capable of switching its discharge capacity to any of a large capacity and a small capacity, and capable of switching between a large capacity and a small capacity. work stably. Background technique [0002] Conventionally, a dual displacement pump described in Patent Document 1 is known as such a dual displacement pump. The dual capacity pump is as Figure 12 The structure shown in the circuit diagram and structural cross-sectional view of the pump body 50 includes: a pump main body 50, which is rotationally driven to suck and discharge liquid; a variable capacity mechanism 52, which can change the discharge capacity per unit rotation of the pump main body 50; and switch The valve 54 selectively communicates the high-pressure side flow path of the discharge pressure and the low-pressure side flow path of the suction pressure with a pressure guiding path that ...

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Problems solved by technology

[0008] However, in the double displacement pump described in Patent Document 1, there is a problem that the displacement of the pump cannot be set to zero because the position of the swash plate 50a is restricted by the abutment position adjustment screw mechanism 52b to define a small displacement.

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