FLOW METER FOR VARIABLE DISPLACEMENT COMPRESSOR

Abstract

A flow meter for a variable displacement compressor comprises a movable body operable to move by differential pressure, a magnet provided in the movable body, a magnetic sensor for detecting change of magnetic flux density of the magnet, a flow passage for refrigerant gas which is discharged from cylinder bores to flow therethrough, a sealed chamber connected perpendicularly to the flow passage and accommodating therein the movable body, an urging member for urging the movable body into the flow passage, a clearance formed between a movable body and an inner wall surface of the flow passage, a by-pass passage opened and closed as the movable body is moved in an axial direction of the movable body, and a communication passage for introducing into the sealed chamber the refrigerant gas in a downstream flow passage of the flow passage which is located downstream of the movable body.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The features of the present invention that are believed to be novel are set forth with particularity in the appended claims. The invention together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIG. 1 is a longitudinal cross-sectional view of a variable displacement compressor of a first preferred embodiment according to the present invention;

FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1;

FIG. 3 is a partially enlarged cross-sectional view of a flow meter of the first preferred embodiment in a low flow rate region;

FIG. 4 is a cross-sectional view taken along the line B-B in FIG. 3;

FIG. 5 is a partially enlarged cross-sectional view of the flow meter of the first preferred embodiment in an intermediate flow rate region;

FIG. 6 is a partially enlarged cross-sectional view of the flow meter of the first preferred embodiment in a high flow rate region;

FIG. 7 is a diagram showing a relation between differential pressure and flow rate;

FIG. 8 is a partially enlarged cross-sectional view of a flow meter of a second preferred embodiment;

FIG. 9 is a partially enlarged cross-sectional view of a flow meter of a third preferred embodiment;

FIG. 10A is a partially enlarged cross-sectional view of a flow meter of a fourth preferred embodiment in a low flow rate region;

FIG. 10B is a partially enlarged cross-sectional view of the flow meter of the fourth preferred embodiment in an intermediate flow rate region; and

FIG. 10C is a partially enlarged cross-sectional view of the flow meter of the fourth preferred embodiment in a high flow rate region.

Claims

1. A flow meter for a variable displacement compressor which comprises a housing having a plurality of cylinder bores, a drive shaft provided in the housing, pistons disposed in the cylinder bores and a swash plate provided on the drive shaft, the pistons being driven by the swash plate, an inclination angle of the swash plate being controlled for controlling a displacement of the compressor, the flow meter comprising: a movable body operable to move by differential pressure;a magnet provided in the movable body;a magnetic sensor for detecting change of magnetic flux density of the magnet;a flow passage for refrigerant gas which is discharged from the cylinder bores to flow therethrough;a sealed chamber connected perpendicularly to the flow passage and accommodating therein the movable body;an urging member for urging the movable body into the flow passage;a clearance formed between a movable body and an inner wall surface of the flow passage;a by-pass passage opened and closed as the movable body is moved in an axial direction of the movable body; anda communication passage for introducing into the sealed chamber the refrigerant gas in a downstream flow passage of the flow passage which is located downstream of the movable body.

2. The flow meter according to claim 1, wherein a plurality of the by-pass passages are provided and spaced in the axial direction of the movable body.

3. The flow meter according to claim 1, wherein an annular groove is formed on an outer peripheral surface of the movable body and opened and closed by a partition which defines the by-pass passage.

4. The flow meter according to claim 3, wherein a position of the groove in the outer peripheral surface of the movable body is set so that the groove is closed by the partition when the movable body is fully urged into the flow passage.

5. The flow meter according to claim 1, wherein a projection is formed on a lower end surface of the movable body, the projection being brought into contact with the inner wall surface of the flow passage when the movable body is fully urged into the flow passage.

6. The flow meter according to claim 1, wherein the housing has a flange for forming the sealed chamber.

7. The flow meter according to claim 6, wherein the magnetic sensor is spaced at a predetermined clearance from the flange.

8. The flow meter according to claim 1, wherein the movable body is cylindrical.

9. The flow meter according to claim 1, wherein the movable body is a spool.

10. The flow meter according to claim 1, wherein the movable body is arranged perpendicularly to the flow passage.

11. The flow meter according to claim 1, wherein the differential pressure is created by a pressure in the sealed chamber and a pressure in the flow passage.

12. The flow meter according to claim 1, wherein the urging member is a coil spring which is disposed in the sealed chamber.