JPS61104184A - Device for detecting abnormality of rotary compressor - Google Patents

Abstract

PURPOSE:To substantially lengthen the life of a compressor, by providing a bushing fitted with a temperature sensor, at a plate where a bearing of shortest life is inserted and the bushing faces the discharge end face of a rotor and the peripheral surface of the shaft of the rotor. CONSTITUTION:A bushing 13 fitted with a temperature sensor 14 is provided at a place where a bearing 5 of shortest life is inserted in a casing 3 and the bushing faces the discharge end face of a rotor 1 and the peripheral surface of the shaft of the rotor. As a result, the shaft vibrates when the bearing 5 is worn out. Since the vibration causes sliding heat on the bushing 13, the abnormality of the bearing 5 is detected through the temperature sensor 14 so that a rotary compressor can be operated until the end of its life, without deteriorating the function of the compressor. Therefore, the period of proper operation of the compressor is maximized and an effective means for making the compressor free from maintenance is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a screw compressor, and more particularly to a method for detecting abnormality in a bearing suitable for making a rotary screw compressor composed of a plurality of bearings maintenance-free.

[Background of the invention]

Conventional maintenance standards for replacing rotary compressor bearings were managed based on the time set by the manufacturer. Due to warranty liability, etc., there is no choice but to replace it, which has the disadvantage that the costs required for replacement (parts cost, replacement procedure) are incurred in a short period of time.

An example of this type of device is Japanese Patent Application Laid-Open No. 59-70895.

[Purpose of the invention]

The purpose of the present invention is to eliminate the method of periodically replacing the bearings of a rotary compressor, and to provide a highly reliable rotary compressor that can be used for the maximum life of the bearing, which has the function of a compressor. It's about doing.

[Summary of the invention]

A rotary compressor composed of a male rotor and a female rotor is composed of four sets of bearings. The lifespan of the four sets of bearings is determined by the rotational speed of each rotor and the shared load generated during the compression stroke, but it is theoretically difficult to design the four sets of bearings with the same lifespan. Furthermore, the length of life of the four sets of bearings differs depending on the discharge pressure in load operation, which is the operating condition of the compressor, and the pressure condition and frequency in no-load operation. However, under any of the above operating conditions, the life span determined by the design calculation among the four sets of bearings is proportional to the operating conditions. It also has the shortest lifespan. Therefore, if we focus only on the bearing with the weakest lifespan among the four sets of bearings and can use it until it reaches the limit where it no longer functions as a rotary compressor, then the best way to understand the lifespan of a rotary compressor is to This is an economical way to use it.

Therefore, in the present invention, as a means to capture the phenomenon that the bearing with the weakest life has reached the end of its life, it is sufficient to stop the compressor without damaging it and replace the bearing at that point. A temperature sensor detects an abnormality in the shaft vibration caused by the wear of the bushes and the generation of frictional heat caused by the sliding of the bushes, and the compressor is stopped for one revolution.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings. First, the structure of the rotary compressor main body will be explained using Fig. 1.The zero-rotation compressor is a positive displacement compressor that applies the principle that the volume generated by the meshing of the male rotor 1 and the female rotor 2 is reduced by the rotation of the rotors. Both rotors are supported by bearings 5 and 6 and bearings 7 and 8, respectively, and are housed in the recasing 3 and the D casing 4. Other main parts that make up the rotary compressor are a mechanical seal cover 10 that isolates the inside of the compressor from the outside air, a bearing cover 11 that isolates the inside of the bearing box from the outside air, and a V-pulley 12 that is a device that transmits drive to the male rotor 9. be.

Figure 1 shows a bush 13 and a temperature sensor in an embodiment according to the present invention, which is close to bearing 4, which has the weakest life among the four sets of bearings, for the purpose of detecting whirling and changes in the axial direction of the shaft. 14 is attached to the D casing 10.

When the male rotor 1 is driven by the drive machine via the V-pulley 12, the female rotor 2 also rotates because it is not meshed with the male rotor 1. When each of the four sets of bearings is new and has not suffered losses such as wear, the normally open rotor rotates normally within vibration amplitudes of 20μ or less in both the d-axis direction and the axis-perpendicular direction. In this state, there is a one-sided gap δ between the outer diameter of the shaft of the male rotor 1 and the inner diameter of the portion of the D casing 4 into which the shaft of the male rotor 1 is inserted, as shown in FIG.
The gap δ3 between the male rotor 1 and the discharge side end face of the male rotor 1 is maintained at a regular size (normally δ□, δ are several tens of microns).

On the other hand, if bearing 5, which has the weakest life among the four sets of bearings that make up the rotary compressor, reaches the end of its life after long-term operation, the radial and axial gaps of the bearing itself will increase. Then, the male rotor rotates while being displaced in the axial direction and in the axial direction by a width corresponding to the gap, and the gaps δ and δ inevitably change. When the gaps δ1 and δ reach 0, the shaft and the D casing come into contact with each other, resulting in seizing and eventually fatal burnout.

According to FIG. 2 of this embodiment, in which a bushing 13 and a temperature sensor 14 are attached to the D casing 4 so as to face the discharge side end face and shaft of the male rotor 1, the bearing at its weakest life has reached a worn state. In this case, the gap δ2 between the inner diameter of the bushing 13 and the outer diameter of the shaft of the male rotor 1 inserted in the D casing 4 is machined to be smaller than δ, and at the same time the male rotor 1
The gap δ4 between the discharge side end face of the male rotor 1 and the end face of the bushing 13 is the gap δ4 between the discharge side end face of the male rotor 1 and the D casing 4.
, the discharge side end face and shaft of the male rotor 1 contact the bushing 13 before contacting the D casing 4. The contact generates wear heat, and the temperature of the bushing 13 reaches a higher temperature than under normal operating conditions. In a normal oil-cooled rotary air compressor, during steady operation with a discharge pressure cuff kgf/=s&g, the temperature of the bush 13 is 90° C., which is approximately the same value as the discharge air temperature. In the case of abnormal conditions due to bearing wear, the temperature reaches 100°C or more. Therefore, the temperature can be detected by the temperature sensor 14 and the compressor can be stopped beforehand, so that the compressor does not suffer from burnout such as seizing, and the bearing, which is the weakest point of life, can reach its maximum potential. The rotary compressor can be operated reliably up to On the other hand, when the discharge air temperature of the oil-cooled rotary air compressor increases due to an increase in oil temperature, etc., a discharge air temperature relay (usually set at 95° C.) operates to protect the compressor. The temperature of the bush 13 exhibits a value lower than the discharge air temperature unless a bearing abnormality occurs.

In addition, in the oil-supplied rotary compressor, lubricating oil is supplied to the bushing 13, and the bushing material is a bearing material, so even if the discharge side end face of the male rotor 1 and the shaft surface come into contact, there will be no damage. In addition, in an oil-free rotary compressor where lubricating oil is not supplied to the pushbutton 13,
A self-lubricating material (for example, carbon, Teflon, etc.) is used for the material, which does not cause loss even if the shaft of the male rotor 1 comes into contact with it.

〔Effect of the invention〕

As described above, according to the present invention, the compressor can be operated to its maximum lifespan without impairing the functions of the rotary compressor caused by burnout such as wear of the bearings, which is the weakest part of the lifespan. , the periodic bearing replacement time, which was conventionally set to less than half of the calculated bearing life, can be extended to the bearing's own life, and detection is possible, making it effective in extending the life of single-rotation compressors and making them maintenance-free. This is economical because the number of overhauls of the screw compressor can be reduced and the costs incurred can be reduced accordingly.

Furthermore, since the bushings and sensors to be attached in the present invention need only be limited to the bearings with the weakest lifespan, the product does not become complicated.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a screw compressor main body according to an embodiment of the present invention, and FIG. 2 is an enlarged view of the portion of FIG. 1 relating to the present invention. DESCRIPTION OF SYMBOLS 1... Male rotor, 2... Female rotor, 3... Casing, 4... D casing, 5, 6, 7, 8... Bearing, 9... Mechanical seal, 10... Mechanical seal cover. 11...Bearing cover, 12...■Pulley, 13
...BUTSUSH, 14...Temperature sensor.

Claims (1)

[Claims] In a rotary compressor, this is the position where the bearing with the weakest life is inserted in the casing that supports multiple bearings, facing the discharge end of the rotor and the surface of the rotor shaft. An abnormality detection device for rotary compressors that has a bush inserted in the position and a temperature sensor attached to the bush.