JPH07247965A - Device for controlling displacement of scroll type compressor - Google Patents

Abstract

PURPOSE:To improve the wear resistance of a screw part of a bypass piston of a scroll type compressor having the bypass piston. CONSTITUTION:A device for controlling the displacement is provided with a bypass hole provided in an end plate of a fixed stroke to allow the outflow of the fluid from a compression chamber to a suction chamber, a bypass piston 130 to open/close the bypass hole, and a motor connected to the bypass piston 130 so as to slide the bypass piston 130 by the rotation of a motor shaft provided with screws. A screw hole 141 on the bypass piston 130 side where a ferrous screw shaft of a motor is fitted is provided in a bush made of bronze bearing material fitted with the bypass piston 130.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacity control device for a scroll compressor.

[0002]

2. Description of the Related Art FIG. 2 is a partial sectional view of a first example of a conventional scroll type compressor with a capacity control device. In the figure, 13 is a cylindrical housing, 42 is a fixed scroll fixed to the housing, 41 is an end plate of the fixed scroll, 52 is a movable scroll, 58 is a suction chamber, and 54 is a tip seal. The end plates of both scrolls are provided with scroll tooth profiles each having an involute curve shape. When the scrolls are engaged with each other, the compression chambers 110, 111,
112 is formed. By rotating the movable scroll 52 with respect to the fixed scroll 42 and causing it to revolve around the axis of rotation, the fluid is taken from the suction chamber 58 into the compression chamber, compressed, and gradually moved to the central portion of the scroll, and discharged (not shown). Discharge fluid from the port into the discharge chamber.

This compressor is provided with a capacity control device having a bypass piston in order to control the capacity of the fluid to be compressed. 121 and 122 are bypass holes provided in the end plate 41 of the fixed scroll, 123x is a bypass cylinder, 124 is a bypass piston, 125 is a spring, 100 is a piston wake chamber, 101 is a bypass piston head chamber, and 126 is an automatic type. It is a pressure control valve.

The capacity control is performed from the suction chamber 58 to the compression chamber 11
This is performed by opening and closing the bypass holes 121 and 122 provided in the compression chambers of the fluids sucked into the suction chambers 0, 111, and 112 by the bypass pistons 124 to the suction chamber 58 side. The position control of the bypass piston 124 guides the control pressure generated by the automatic pressure control valve 126 or the electric pressure control valve from the discharge pressure gas and the suction pressure gas to the bypass piston head chamber 101, and the control pressure and the spring 125. And bypass piston wake chamber 10
The pressure is zero (actually, it can be approximated to the suction pressure). When the compressor is not in operation, discharge pressure = suction pressure = control pressure, and the spring force causes the bypass hole to be fully opened as shown in FIG.

However, in the conventional method, since the control valve for generating the control pressure from the discharge pressure gas and the suction pressure gas is used, the bypass hole area and the bypass hole position are sufficient in order to obtain a highly efficient and wide range capacity control rate. With a large and widely installed compressor, most of the fluid drawn into the compression chamber flows out from the bypass hole at low speed start-up at low outside air temperature.
Discharge pressure ≈ suction pressure (suction pressure ≈ control pressure), causing an uncontrollable region. Therefore, in order to make the uncontrollable region as narrow as possible, the efficiency and the capacity control rate may actually be sacrificed to some extent. Further, in the conventional method, since the control valve that generates the control pressure from the discharge pressure gas and the suction pressure gas is used, the influence of the state of the discharge pressure gas flowing into the control valve, that is, the amount of oil mixed, the discharge pressure pulsation, etc. In some cases, the control pressure characteristic changed and deviated from the required control characteristic.

In order to solve this problem, the applicant of the present invention previously proposed a structure in which a drive motor is directly coupled to a bypass piston via a motor shaft and the bypass piston is directly operated by an electric signal. Annual patent application 1026
Filed under No. 45. FIG. 3 is a partial cross-sectional view of the proposed scroll type compressor, which is a second example of the prior art. This compressor is a scroll type compressor with a displacement control device that operates by directly connecting a drive motor and a bypass piston.

In the drawing, 123 is a bypass cylinder,
130x is a bypass piston slidably mounted in the cylinder, 130a is a screw hole provided in the piston, 130b is a pin hole into which a pin for stopping rotation is inserted, 131 is a drive motor, and 131a is the same. Is the axis of rotation of the motor, extended to drive the bypass piston,
The extension has a screw. This screw is rotatably engaged with the screw hole 130a of the bypass piston.
The rotary shaft of the motor is made of iron-based material. 1
Reference numeral 31b is a rotation preventing pin attached to an eccentric position of the motor, and is a pin hole 130b of the bypass piston.
It is slidably inserted in. Reference numeral 132 denotes a snap ring for preventing and fixing the motor in the radial direction, and 13
Reference numeral 3 is a fixing member for preventing rotation of the motor and fixing, 134 and 135 are terminals, and 136 is a lead wire for supplying a current to the motor. FIG. 4 is an enlarged sectional view of the bypass piston 130x. The configuration other than the above is the same as that of the first example (FIG. 2) of the prior art.

A pulse motor is used as the drive motor 131, and the rotational position of the rotor can be arbitrarily set according to the sign and number of pulses. This rotation is the rotation of the drive shaft of the motor, and the radial position of the bypass piston is controlled via the screw of the screw hole. This controls the opening degree of the bypass holes 121 and 122.

[0009]

In such a scroll-type compressor with a capacity control in which the drive motor and the bypass piston are directly connected to operate, the material of the bypass piston keeps the piston clearance constant during operation. A material having a coefficient of linear expansion equivalent to that of the material is used, and usually an aluminum alloy is used. Therefore, since the screw hole of the piston that is screwed into the drive shaft of the motor is also made of aluminum alloy, wear resistance is poor. The present invention is intended to provide a capacity control device in which the wear resistance of this portion is improved.

The present invention is intended to improve the wear resistance of the thread portion of the bypass piston.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a fixed scroll having an end plate and an involute curved scroll tooth profile and a movable scroll are meshed with each other to form a scroll tooth profile of both scrolls. A closed compression chamber is formed between the fixed scroll and the movable scroll so as to prevent them from rotating and revolve, thereby taking in fluid from the suction chamber into the compression chamber and compressing it gradually toward the center of the scroll. The present invention relates to a displacement control device for a scroll compressor, which has the following features, in a displacement control device for a scroll compressor that moves and discharges from a central portion. (1) A bypass hole provided in the end plate of the fixed scroll to allow the fluid to flow from the compression chamber to the suction chamber, a bypass piston for opening and closing the bypass hole, and a motor shaft provided with a screw. A bronze-based bearing material having a motor connected to the bypass piston so as to slide by rotation and having a screw hole on the side of the bypass piston on which the iron screw shaft of the motor is mounted It was provided on the bush made. (2) In the capacity control device for a scroll compressor according to the item (1), the bush is mounted and fixed to the bypass piston by press fitting, casting, caulking, bonding, or welding. (3) In the displacement control device for a scroll compressor according to the item (1), the bypass piston is made of an aluminum alloy material.

[0012]

In the present invention, since a bush made of a bronze-based bearing material having good slidability, wear resistance, and seizure resistance is used for the screw portion that operates the bypass piston, it is possible to improve reliability. it can.

[0013]

1 is a sectional view of a bypass piston according to an embodiment of the present invention. In the figure, reference numeral 130 is a bypass piston, 140 is a bush mounted and fixed to the piston, 141 is a screw hole provided in the bush, and is a portion to which a screw of an extension portion of a rotation shaft of a motor is screwed. .

A bush 1 made of a bronze-based bearing material is provided in a portion of the bypass piston 130 which constitutes the screw hole 141.
40 is integrally attached to the piston 130 by press fitting, casting, caulking, bonding, welding or the like, and the bush is provided with a screw hole 141. This bypass piston 1
Numeral 30 is incorporated in a scroll type compressor with capacity control as in FIG. The configuration other than the above is the same as that of the second example (FIG. 3) of the prior art.

In this embodiment, the screw portion for operating the bypass piston is made of a material having good slidability, abrasion resistance and seizure resistance, so that reliability can be improved.

[0016]

In the capacity control device of the scroll compressor of the present invention, the bypass hole provided in the end plate of the fixed scroll so as to allow the fluid to flow from the compression chamber to the suction chamber, and the bypass hole. Bypass piston that opens and closes
A motor connected to the bypass piston so that the bypass piston is slid by rotation of a motor shaft provided with a screw, and a screw hole on the bypass piston side in which the iron-based screw shaft of the motor is mounted is used as the bypass piston. Provided on the mounted bush made of bronze bearing material. Alternatively, the bush is press-fitted into the bypass piston, cast,
Since it is attached and fixed by caulking, bonding, or welding, the wear resistance of the threaded portion of the bypass piston can be increased and the reliability can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a bypass piston according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a first example of a conventional scroll type compressor with a capacity control device.

FIG. 3 is a partial cross-sectional view of a second example of a conventional scroll type compressor with a capacity control device.

FIG. 4 is a partial cross-sectional view of a bypass piston of a second example of the conventional scroll compressor with a capacity control device.

[Explanation of symbols] 130 bypass piston 140 bush 141 screw hole

Claims (3)

[Claims] 1. A fixed scroll having an end plate and a scroll tooth profile having an involute curve and a movable scroll are meshed with each other to form a sealed compression chamber between the scroll tooth profiles of both scrolls. In the displacement control device of the scroll compressor, which blocks the rotation of the orbiting movable scroll and causes it to revolve, and gradually moves to the scroll central portion while taking in and compressing the fluid from the suction chamber to the scroll central portion, By a bypass hole provided in the end plate of the fixed scroll to allow the fluid to flow out from the compression chamber to the suction chamber, a bypass piston for opening and closing the bypass hole, and a motor shaft provided with a screw to rotate the bypass shaft. And a motor connected to the bypass piston so as to slide the bypass piston. The bypass piston side screw hole in which the iron type screw shaft is mounted is provided in a bush made of a bronze-based bearing material mounted in the bypass piston. 2. The capacity control device for a scroll compressor according to claim 1, wherein the bush is mounted and fixed to the bypass piston by any one of press fitting, casting, caulking, bonding, and welding. 3. The capacity control device for a scroll compressor according to claim 1, wherein the bypass piston is made of an aluminum alloy material.