JPS6323394B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for preventing noise in screw compressors for compressing refrigerant used in refrigerators, air conditioners, etc.

[Conventional technology]

As shown in FIG. 1, the screw compressor consists of a male rotor 1 having a spiral ridge and a female rotor 2 having a spiral groove that engages with the spiral ridge, both ends of which are closed by a front case 3 and a rear case 4. When rotating within the working chamber 6, which consists of two parallel and overlapping cylindrical cavities formed in the case 5, the limit is set by the interlocking spiral ridges, spiral grooves, and the inner surface of the working chamber 6. During this time, gas is sucked into the sealed action space 7 from the suction passage 8 communicating with an inlet (not shown), compressed, and discharged from the discharge port 18 via the discharge passage 9. It is configured.

Furthermore, the discharged gas passes through an oil separator element 10 for separating oil contained therein, is discharged from a discharge port 11 into the housing 12, and is sent out to the outside of the compressor via a discharge pipe 13. There is. Further, the oil separated by the element 10 accumulates in the lower part of the housing 12 from the oil drain hole 19 of the element 10. Reference numeral 14 denotes oil stored in the lower part of the housing 12, which is injected from an oil injection orifice 15 provided in the rear case 4 through a groove 16 into the sealed working space 7.

[Problem that the invention seeks to solve]

As described above, in a screw compressor having a sealed working space 7 that changes sequentially as the rotors 1 and 2 rotate, when the discharge gas pressure at the outlet of the discharge passage 9 and the pressure inside the discharge pipe 13 are different, Large pressure fluctuations occur due to gas flowing backwards or blowing out, which causes the housing 12 to
Excite the internal space. For this reason, rear case 4
a transverse annular cavity 17 with a protrusion and a separator element 10 and a housing 12 surrounding it;
When the resonance frequency of the cavity 17 matches the frequency of the pressure fluctuation, there is a problem in that very loud noise is generated.

The present invention attempts to reduce the above-mentioned compressor noise.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention is directed to a male rotor having a helical ridge and a female rotor having a helical groove, which are limited by a helical ridge, a helical groove, and an inner surface of the working chamber that engage when the rotor rotates within the working chamber. The oil-containing gas discharged from the closed working space passes through the oil separator element to separate the oil, and then exits the housing through a transverse annular cavity bounded by the element and the housing surrounding it. The screw compressor is characterized in that the liquid level of the oil separated by the element and stored in the housing is set to be higher than the lower surface of the element.

[Effect]

The resonant frequency of the annular cavity described above depends on the amount of oil in the housing, and the cavity resonance that occurs when the amount of oil does not come into contact with the lower surface of the oil separator element is different from that when it does come into contact with it. In other words, when the amount of oil does not touch the bottom surface of the oil separator element, the resonance mode of the annular cavity occurs.On the other hand, when the amount of oil comes into contact with the bottom surface of the oil separator element, the cavity becomes a horseshoe shape. The noise of the compressor when these resonance phenomena occur depends on the volume of the cavity in which resonance occurs, so the latter resonance mode of the horseshoe-shaped cavity is smaller.

Therefore, if the oil level in the housing is always set above a certain value, that is, above the bottom surface of the oil separator element, the compressor noise can be reduced even if resonance occurs.

〔Example〕

The present invention will be explained below based on examples. The configuration of the screw compressor is as described above, and here, the oil level of the oil 14 stored in the horizontal annular cavity 17 bounded by the oil separator element 10 and the housing 12 during compressor operation is The amount of oil to be charged to the compressor is determined so that the amount is equal to or higher than the bottom surface of the oil separator element 10, or the volume of the cavity 17 is determined so that the above relationship is maintained, or the volume of the oil injection orifice 15 determine the position of

In this way, when the oil level of the oil 14 stored in the annular cavity 17 is made to be higher than the lower surface of the oil separator element 10, the cavity 17
Since the lower part is divided by the oil level, it presents a horseshoe-shaped cavity. Here, the resonance frequency in the cavity depends on the amount of oil in the housing 12, and the cavity resonance that occurs when the oil level does not touch the lower surface of the oil separator element 10 is different from that when it does. To explain this using Figure 3,
(A) shows the resonance mode of the annular cavity when the oil surface does not touch the bottom surface of the oil separator element 10, and (B) shows the resonance mode of the horseshoe-shaped cavity when the oil surface comes into contact with the bottom surface of the oil separator element 10. ,
The noise of the compressor when these resonance phenomena occur depends on the volume of the cavity in which resonance occurs, so the resonance mode of the horseshoe-shaped cavity shown in (b) is smaller. That is, in FIG. 4, the noise in the resonance mode (a) of FIG. 3 is shown by a solid line, and the noise in the resonance mode (b) of FIG. 3 is shown by a broken line.

Therefore, if the oil amount is determined so that the oil level in the housing 12 is always above a certain value, the compressor noise will be low even if cavity resonance occurs.

Note that the resonance frequency of the horseshoe-shaped cavity changes depending on the oil level, but by determining the oil level so that this does not match the frequency of pressure fluctuations of the discharged gas, compressor noise can be further reduced. Ru.

As mentioned above, the oil level is determined by the amount of oil charge,
Alternatively, it can be easily changed by appropriately determining the volume of the cavity 17 or the position of the oil injection orifice 15.

〔Effect of the invention〕

As described above, according to the present invention, the male rotor having a helical ridge and the female rotor having a helical groove are bounded by the helical ridge, the helical groove, and the inner surface of the working chamber that engage when rotating in the working chamber. The oil-containing gas discharged from the closed working space passes through the oil separator element to separate the oil, and then exits the housing through a transverse annular cavity bounded by the element and the housing surrounding it. In a screw compressor configured to discharge oil, the liquid level of the oil separated by the element and stored in the housing is set to be higher than the bottom surface of the element, so that the noise of the screw compressor can be reduced by an extremely simple means. We were able to reduce it.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view of a screw compressor to which the present invention can be applied, FIG. 2 is a sectional view taken along line AA in FIG. 1, and FIG. 3 is a diagram showing the mode of cavity resonance.
FIG. 4 is a diagram showing the relationship between frequency and noise level. Male rotor…1, female rotor…2, working chamber…6, sealed working space…7, oil separator element…
10, Housing...12, Oil...14.

Claims (1)

[Claims] 1 Contains oil delivered from a closed working space bounded by the helical ridges and grooves and the inner surface of the working chamber that interlock when the male rotor with helical ridges and the female rotor with helical grooves rotate within the working chamber. A screw compressor, wherein the gas flows through an oil separator element to separate oil and then is discharged out of the housing through a transverse annular cavity bounded by the element and the housing surrounding it, A method for preventing noise in a screw compressor, characterized in that the liquid level of oil separated by the element and stored in the housing is set to be higher than the lower surface of the element.