JPH06159271A - Oil cooling type screw compressor - Google Patents

Abstract

PURPOSE:To restrain tooth surface separation of a female rotor so as to reduce vibration and noise by adding a predetermined correcting value to the lead of either one of female and male rotors so as to make both rotors contact with each other on an advance surface side or a backward surface side in order to have no backlash. CONSTITUTION:A pair of female and male rotors 11, 12 are stored in a casing 13, and are supported by bearings 14, 15; 16, 17 on the intake and compression (discharge) sides thereof. Further, a female rotor 12 is driven for rotation in association with the drive rotation of the male rotor 11 so that air is introduced through a suction port 18 and is compressed, and thereafter, is discharged from a discharge port 19. In this case, a predetermined correcting value is added to the lead of either one of the female and male rotors 11, 12. Further, no backlash is present between the female and male rotors 11, 12 so that tooth surface separation of the female rotor can be eliminated. Further, excessive abrasion of the tooth surface caused by tooth clattering can be eliminated, and lowering of the function caused by leakage of compressed air can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil-cooled screw compressor which can be used as an oil-cooled screw pressure vertical machine and a screw refrigerator.

[0002]

2. Description of the Related Art In an oil-cooled screw compressor composed of a pair of male and female screw rotors, a female rotor rotates following a male rotor on the drive side, and contact is made on the forward side of the meshing portion of each rotor. It rotates in the state of doing.

Since a certain gap is maintained on the backward surface side of the meshing portion, the female rotor is provided with a backlash that can freely rotate in the circumferential direction within the range of this gap.

Machining accuracy error of rotor tooth profile (lead error,
(Profil error, etc.) or the exciting force due to the gas torque fluctuation acting on the female rotor due to the pressure fluctuation during the operation causes the rotational speed of the female rotor to become unequal to cause uneven rotation. This rotation unevenness acts on the advance side of the rotation direction (advancing surface side) or the delay side of the counter rotation direction (reverse surface side). When the rotation unevenness occurs on the advancing side, the female rotor advances in the rotational direction by the amount of backlash, so that the male rotor and the female rotor contact each other on the reverse surface side. On the contrary, when the rotation unevenness occurs on the delay side, the female rotor is delayed in the counter-rotational direction, so that the rotor contacts on the forward side. The direction of uneven rotation does not always act in a fixed direction but changes periodically.

Therefore, in the male and female rotors, the contact on the advancing surface or the reverse surface is continuously repeated at a high frequency, so that the tooth surface separation of the so-called male rotor occurs, and the vibration and noise due to gear ratcheting increase.

This tooth surface separation occurs during no-load operation (when the suction throttle valve is fully closed and the suction pressure is a negative pressure) than during full-load operation (normal discharge pressure of 7 kgf / cm ² · g). Easy to do. As a publicly known example for this countermeasure, there is JP-A-3-992.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the tooth surface separation vibration of the female rotor to reduce the vibration and noise.

[0008]

[Means for Solving the Problems] As a means for suppressing the tooth flank separation of a female rotor, the meshing of male and female rotors is advanced on the suction side end face by adding a certain amount of correction to the rotor lead to a theoretical value. Surface and contact on the discharge side end surface on the reverse side surface side (or vice versa, contact on the suction side end surface on the reverse side side and on the discharge side end surface on the forward side surface side). As a result, the backlash between the male and female rotors is reduced to zero, and the tooth surface separation of the female rotor is suppressed.

[0009]

[Function] Theoretical lead of the female rotor (forward side and reverse side)
On the other hand, the correction amount on the plus side corresponding to the backlash is added to the corresponding lead on the discharge side end face when the suction side end face is used as a reference. As a result, the suction-side end surface makes contact with the forward-moving surface side, and the discharge-side end surface makes contact with the backward-moving surface side.

As an alternative, by setting the lead correction amount to the negative side, the suction side end surface makes contact on the reverse side surface side, and the discharge side end surface makes contact on the advance side surface side.

As a second alternative, with respect to the theoretical lead of the female rotor (advancing surface side and backward moving surface side), the lead on the discharge side end surface when the suction side end surface is used as a reference is corrected on the plus side corresponding to backlash. Add the amount. As a result, the suction-side end surface makes contact with the forward-moving surface side, and the discharge-side end makes contact with the backward-moving surface side.

As an alternative 3, by making the lead correction amount of the alternative 2 negative, the suction side end face is in contact with the reverse side surface side, and the discharge side end face is in contact with the forward side surface side.

By thus adding the correction amount to the theoretical lead, the male and female rotors can be brought into contact with each other on both the advancing face side and the reverse advancing face side, and the backlash can be made zero.

[0014]

Embodiments of the present invention will be described with reference to FIGS.

FIG. 1 shows a flow sheet of an oil-cooled screw compressor unit. The air sucked from the suction throttle valve 1 is pressurized by the compressor 2 to a predetermined pressure, separated by the oil separator 4, and then passed through the pressure regulating valve 5 and the check valve 6 to be cooled by the aftercooler 7. It is ejected later.

The oil accumulated in the oil separator 5 circulates due to the pressure difference between the oil separator 5 and the oil supply port of the compressor 2, is cooled by the oil cooler 8, passes through the oil filter 9, and passes through the compressor 2 Is refueled.

FIG. 2 shows an assembled sectional view of the oil-cooled screw compressor. The pair of male rotor 11 and female rotor 12 is housed in a casing 13, and is supported by bearings 14 and 15 on the suction side and combined bearings 16 and 17 on the discharge side.

By driving the male rotor 11, the female rotor 12 is driven to rotate, and the air sucked from the suction port 18 is compressed as the rotor rotates and is discharged.
It is discharged from 9.

FIG. 3 is a sectional view perpendicular to the axis of the male rotor 11 and the female rotor 12 in FIG. 2, viewed from the suction side. In the case of this example, the male rotor has five teeth and the female rotor has six teeth.

FIG. 4 is a view in which the twist line on the outer circumference of the addendum of the male rotor is developed in the axial direction and the circumferential direction. The horizontal axis represents the developed dimension in the circumferential direction, and the vertical axis represents the deployed dimension in the axial direction.

The distance traveled in the axial direction by one revolution of the teeth of the male rotor is called the lead of the male rotor, and the symbol is L.
Expressed in _M (unit: mm / rev.). The outer diameter of the male rotor is D _M ,
If the total winding angle is ψ _M and the axial length of the rotor is L, the lead L _M = L × 360 / ψ _M , and the twist angle at the outer circumference of the tooth tip is β _M = tan to ¹ (π · D _M / L _M) to become. Here, the full winding angle ψ _M is an angle at which the male rotor tooth tip is twisted and rotated from the suction side end surface to the discharge side end surface of the rotor.

In the figure, when the lead L _M of the male rotor is a theoretical value (when the correction amount is not added), the twist line of the tooth tip of the male rotor is shown by a solid line, whereas the lead correction amount ΔL _M The twisted line of the addendum is shown by a broken line.
In this case, the corresponding lead correction amount ΔL _M ′ at the discharge side end surface
Corresponds to the correction amount at the position where the axial length is L as shown in the figure. As a result, the tooth profile of the male rotor at the end face on the discharge side rotates and moves in the counter-rotational direction by the lead correction of ΔL _M ′ with respect to the end face on the suction side.

FIG. 5 is a sectional view perpendicular to the rotor axis showing the meshing of the tooth profiles of the male rotor and the female rotor on the suction side end face at a certain rotation angle. The male rotor and the female rotor make contact with each other on the advancing surface on the rotation direction side and rotate, and on the reverse surface on the anti-rotation direction side,
There is a gap between the rotors and backlash is maintained.

FIG. 6 is a sectional view perpendicular to the axis of the rotor showing the meshing of the tooth shapes of the male rotor and the female rotor when viewed from the discharge side end surface.

As described above, the end surface on the discharge side is shaped like the tooth profile on the suction side, and the male rotor tooth profile is rotationally moved in the counter-rotational direction side by the amount corresponding to the lead correction amount ΔL _M ′.

By making this rotational movement amount equal to the backlash amount at the suction side end face, it is possible to make contact on the reverse side. That is, the pitch circle diameter PC _M of the male rotor side, when the backlash in the suction end of a pitch circle diameter _{B, ΔL M '= L M} × B / (PC M
X π).

From the above, the suction side makes contact with the advancing surface and the discharge side makes contact with the advancing surface and rotates. For this reason, the female rotor is pressed against both the forward and backward surfaces to be driven to rotate, and the backlash between the rotors becomes zero, so that the tooth profile of the female rotor is not separated.

[0028]

According to the present invention, it is possible to reduce the rattling noise caused by the separation of the tooth flanks of the rotor and the vibration of the rotor. Further, since abnormal wear of the tooth surface due to tooth striking is eliminated, it is possible to prevent performance deterioration due to leakage of compressed air from the worn portion.

[Brief description of drawings]

FIG. 1 is a flow sheet of an oil-cooled screw compressor unit of the present invention.

FIG. 2 is an assembled sectional view of an oil-cooled screw compressor body of the present invention.

FIG. 3 is a sectional view of the present invention in a direction perpendicular to the rotor axis.

FIG. 4 is a development view of a male rotor tooth tip of the present invention.

FIG. 5 is a sectional view of the suction side of the present invention in a direction perpendicular to the rotor axis.

FIG. 6 is a sectional view of the discharge side of the present invention in a direction perpendicular to the rotor axis.

[Explanation of symbols]

1 ... Suction shutoff valve, 2 ... Compressor body, 3 ... Motor, 4 ... Oil separator, 5 ... Pressure regulating valve, 6 ... Check valve, 7 ... After cooler, 8 ... Oil cooler, 9 ... Oil filter, 1
1 ... Male rotor, 12 ... Female rotor, 13 ... Casing, 1
4 ... Bearing, 15 ... Bearing, 16 ... Combined bearing, 17 ... Combined bearing, 18 ... Suction port, 19 ... Discharge port.

Claims (1)

[Claims] 1. An oil-cooled screw compressor comprising a pair of male and female screw rotors, wherein a certain correction amount is added to the lead of either male or female rotor so that the male and female rotors are on the advancing side on the suction side. The oil-cooled screw compressor is characterized in that it makes contact with the reverse side on the discharge side to eliminate backlash between rotors.