JPS6341689A - Screw compressor - Google Patents

Abstract

PURPOSE:To restrain the vertical movement and rotation of a slide valve and prevent the wear of a screw rotor by bringing the end face of said slide valve into whole-face contact with the wall face of a casing when said slide valve is fully opened. CONSTITUTION:Both the discharge side end face 14 of a casing 4 and the discharge side end face 15 of a slide valve 7 are vertically formed and are brought into whole-face contact with each other when the slide valve 7 is fully opened. By this structure, the vertical movement and the rotation of the slide valve 7 is restrained due to the whole-face contact of the discharge side end face 15 of the slide valve 7 with the discharge side end face 14 of the casing 4, and the contact between a screw rotor 1 and a slide valve 7 can be prevented, thereby, preventing the generation of unusual sound and the wear of the screw rotor 1 resulting from said contact.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a screw compressor having a slide valve.

[Conventional technology]

In conventional screw compressors, as described in Japanese Patent Publication No. Sho 56-17557, a slide valve system is often used for the first rock structure on the capacity side. Then, during the operation Vi, the slide valve opens and closes depending on the load, and a portion of the compressed gas is returned to the suction side to perform capacity control operation. The slide valve is configured to be moved by a piston that is operated by hydraulic pressure, and a part of the slide valve has an arc shape that follows the semicircle of the rotating screw rotor. Some of the parts may come into contact with the rotating screw rotor and generate abnormal noise. If such a situation occurs, the screw rotor will wear more severely, leading to a decrease in performance.

In particular, when starting up, it is common practice to fully open the slide valve and start-up, but when starting up, liquid refrigerant? In some cases, suction sludge is compressed, and in such a case, large pressure fluctuations occur inside the screw rotor and in the discharge chamber.

Since the slide valve placed in such an environment has no stopper etc., it is in a free state, and bending stress is generated in the rod that connects the piston and the slide valve, and the range of the gap on the outer periphery of the slide valve is You can freely move up and down and rotate inside. For this reason, sufficient consideration has not been given to the fact that the rotating screw rotor and a portion of the slide valve come into contact with each other, causing wear on the screw rotor.

[The problem that the invention is trying to solve]

The above-mentioned conventional technology does not give sufficient consideration to the fact that the slide valve comes into contact with the rotating screw rotor and causes the screw rotor to wear out, and there is a problem in that the performance deteriorates due to the wear of the screw rotor.

The object of the present invention is to eliminate contact with the screw rotor of the slide valve and to eliminate wear on the screw rotor.

[Failure to solve the problem]

The above object is achieved by providing means for completely restraining the vertical and rotational movements of the slide valve between the slide valve and the discharge side wall surface of the casing.

[Operation] When the slide valve is fully opened VC, the slide valve moves furthest toward the discharge side of the casing, and is positioned so that the end surface of the slide valve comes into contact with the discharge side wall surface of the casing. The vertical and rotational movements of the slide valve are restricted by the contact friction between the two.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

A screw rotor 1 is rotatably supported in a casing 4 by a radial bearing and a thrust bearing (not shown). Reference numeral 6 denotes a discharge chamber, which is connected to the entire compression chamber of the screw rotor 1, and is also tangential to the discharge pipe.

A slide valve 7 is integrally formed with a piston 9 by a rod 8. The slide valve element is slidably housed with an appropriate gap maintained between the screw rotor 1 and the inner wall 41 of the casing 4. 1
0 is an end face on the suction side of the slide valve, which comes into close contact with the end face 42 of the casing 4 during full load operation to close the slide valve. It communicates with the low pressure side through an 11 bypass passage. 12 is a cover of the hydraulic cylinder 13. 14 is a discharge side end face of the casing 4, and 15 is a discharge side end face of the slide valve 7. These end surfaces are vertically formed and in full contact with each other to constitute a means for restraining the vertical and rotational movements of the slide valve 7. FIG. 2 shows a case where the discharge side end face 17 of the slide valve 16 and the discharge end face 19 of the casing 18 are inclined and brought into full contact with each other. Figure 3 shows slide valve 1
The discharge side surface 20 of 9 is formed into a protruding shape and is formed only on the side of the screw rotor 1 from the axis of the rod 8, that is, on the lower side of the rod 8 in the figure.

Next, its effect will be explained.

The figure shows a state in which the slide valve is activated and moved to the farthest discharge side. This state corresponds to the minimum capacity of the compressor, and the discharge side end surface 15 of the slide valve 7 is connected to the casing 4.
The entire surface is in contact with the discharge side end surface 14 of. At this time, the piston 9 is some distance from the cover 12. By determining the position of the slide valve in this manner, when the screw compressor is started, the slide valve is moved to the discharge side end surface 15 of the casing 4 by the driving force acting in the right direction in the drawing of the piston 9. The vertical movement and rotational movement of the slide valve 7 are restricted. Therefore, there is an effect of completely preventing the generation of abnormal noise due to contact between the screw rotor 1 and the slide valve 7 and the wear of the screw rotor 1. Further, since the slide valve 7 is restrained, the stress acting on the rod 8 is only the tensile stress due to the driving force of the piston/9, and the excessive bending stress that has been a problem in the past does not occur.

Further, as shown in FIG. 2, the discharge side end surface 17 of the slide valve 16
By tilting the discharge side end surface 19 of the casing 18 so that they are in full contact with each other, the reaction force acting on the contact surface of the discharge side end surface 17 of the slide valve 16 against the driving force of the piston 9 is applied along the contact surface. Since the tangential component acts in the direction of pushing up the slide valve 16, contact between the slide valve 16 and the screw rotor 1 can be more reliably prevented.

In addition, as shown in FIG. 3, the discharge side end surface 2 of the slide valve 21
If 0 is made into a protruding shape, the slide valve 19 will be moved clockwise due to the difference in the position of action between the driving force of the piston 9 acting on the axis of the rod 8 and the reaction force on the discharge side end surface of the slide valve 21. A rotational force is generated to rotate the slide valve 2.
1 is pushed upward and the inner wall 41 of the casing 4
Contact with and restrict vertical and rotational movements.

〔Effect of the invention〕

According to the present invention, since it is possible to eliminate contact between the slide valve and the screw rotor, wear of the screw rotor can be prevented.

[Brief explanation of the drawing]

1 to 3 are partial cross-sectional views of one embodiment of the present invention. 1...Screw rotor 4...Casing"/
, +6, 2 +...Slide valve 8=-rod 9...Piston +5,17.20...Discharge side end face of slide valve 14.19...Discharge side end face of casing.

Claims (1)

[Claims] 1. In a screw compressor having a slide valve, when the slide valve is fully opened, the vertical movement and rotational movement of the slide valve in which the end face of the slide valve and the wall surface of the casing come into contact are controlled. A screw compressor characterized by being provided with a means for restraining. 2. The screw compressor according to claim 1, wherein the restraining means is such that the end face of the slide valve and the wall face of the casing are in full contact with each other in a vertical or inclined manner.