JPH0874748A - Dry screw fluid machine - Google Patents

Abstract

PURPOSE: To enhance performance by maintaining each gap optimum between rotors and between each rotor and a casing when the machine is in operation. CONSTITUTION: Each rotor tooth crest 4 and each rotor tooth root 5 of a screw rotor 1 are made gradually thin from its suction side 9 toward its discharging side 10, a chip 3 is provided for each rotor tooth crest, and each distance between the tip end of each chip and the axial center of each rotor is identical at its suction side 9 and its discharging side 10. Therefore, since this constitution thereby allows each gap between the rotors and between each rotor and the casing to be kept optimum when the machine is in operation, performance can thereby be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry screw fluid machine in which a male rotor and a female rotor rotate while meshing in a non-contact manner.

[0002]

2. Description of the Related Art In the prior art, for example, an actual Kaihei 3-
As described in Japanese Patent No. 77084, the outer diameter of the rotor is tapered from the suction side to the discharge side in accordance with the axial distribution of the amount of thermal deformation of the rotor so that the gap between the rotors in the operating state is optimally maintained. I was doing.

[0003]

However, in the taper rotor as described above, the clearance between the rotors during operation can be made small, but the clearance between the rotor and the casing is not taken into consideration, and other than thermal deformation of the rotor. For example, due to elastic deformation of the rotor when centrifugal force is applied due to unbalance, bending of the rotor due to gas pressure in the rotor tooth groove, play and elastic deformation of the bearing, and difference in the amount of thermal deformation of the rotor and the casing, the diameter of the tapered rotor increases. There was a possibility that the outer diameter of the rotor and the inner wall of the casing would come into contact with each other. Further, in order to prevent this, it is necessary to reduce the taper amount of the tooth profile of the rotor, it is not possible to sufficiently compensate for the thermal deformation of the rotor, and there is a problem that the clearance between the rotors cannot be reduced and the performance deteriorates.

An object of the present invention is to obtain a dry screw fluid machine having a screw rotor in which a clearance between rotors during operation and a clearance between a rotor and a casing are optimized.

Another object of the present invention is to manufacture a rotor at low cost.

Still another object of the present invention is to obtain a dry screw fluid machine having a screw rotor having a reduced difference in rotor temperature between the suction side and the discharge side and a reduced taper amount.

[0007]

The above object is to rotatably support a male rotor and a female rotor in a casing,
In a dry screw fluid machine in which the two rotors rotate while meshing without contacting each other, the two rotors are formed in consideration of elastic deformation during operation, and a tip is provided on a tooth tip of at least one of the rotors. This chip is achieved by molding in consideration of thermal deformation of the chip during operation.

Another object of the present invention is to provide a dry screw fluid machine in which a male rotor and a female rotor having a screw shape are rotatably supported in a casing, and the rotors are rotated while meshing with each other without coming into contact with each other. The tip diameter and the root diameter of the rotor are increased on the low temperature side relative to the high temperature side of the rotor during operation, and a tip is provided on the tooth tip of at least one of the rotors, and the tip of this tip and this tip are provided. This is achieved by keeping the distance from the rotor axis from the high temperature side to the low temperature side.

A further object of the present invention is to provide a dry screw fluid machine in which a male rotor and a female rotor, which are screw-shaped, are rotatably supported in a casing and rotate while meshing without contact between the rotors. The tip diameter and the root diameter of the rotor are made larger on the suction side with respect to the discharge side, a tip is provided on the tooth tip of at least one of the rotors, and the tip of this tip and the axial center of the rotor having this tip Is achieved by keeping the distance from the suction side to the discharge side constant.

Further, the above object is to provide a dry screw fluid in which a male rotor and a female rotor in a screw shape are rotatably supported by bearings attached to both ends of the rotor, and the rotor rotates while meshing with each other without contact in the casing. In the machine, the two rotors are formed in consideration of the amount of thermal expansion during operation, tips are provided on the tooth tips of at least one of the rotors, and the tips of the tips and the axial center of the rotor having the tips are formed. The distance is the amount of elastic deformation of the rotor during operation,
This is achieved by setting at least one of the play and elastic deformation amount of the bearings supporting the rotors and the thermal deformation amount of the inner diameter of the casing.

A further object of the present invention is to provide a dry screw fluid machine in which a screw-shaped male rotor and a female rotor are rotatably supported in a casing, and both rotors rotate while meshing with each other without making contact with each other. At this time, the rotor temperature at the time of discharge, the discharge side, the thermal expansion amount of both rotors is obtained with reference to the rotor temperature at the time of load operation, this rotor is molded, and chips are provided on the tooth tips of at least one of the rotors. The distance between the tip of the tip and the shaft center of the rotor having the tip is set to be constant between the suction side and the discharge side.

[0012]

[Operation] In the operating state, the clearance between rotors can be optimally maintained by the taper rotor, and the clearance between the rotor and casing can be optimally maintained by the tips of the rotor tooth tips, reducing air leakage from the clearances and improving performance. it can. Even when the design condition temperature of the taper rotor is not reached in the operating state, the wear of the tip is reduced, and the clearance between the rotor and the casing is maintained optimally, so that the performance is not deteriorated.

Further, by preliminarily processing the tip outer diameter into a shape that takes into consideration the deflection of the rotor, the play of the bearing, the elastic deformation, and the thermal deformation of the casing, it is possible to reduce the amount of wear of the tip during operation and improve the reliability. improves.

Next, by making the difference between the tip diameter of the rotor and the diameter of the bottom of the rotor the same on the suction side and the discharge side, the rotor can be processed with one kind of cutter, so that the rotor can be manufactured at low cost. it can. In this case, the outer diameter processing of the tip portion is performed separately, but the processing in the width direction of the tip may be performed simultaneously. Further, if the reduction rate of the root diameter from the suction side to the discharge side is made constant, taper processing can be performed by increasing the cutter drive amount at a constant rate in the axial direction, so that the rotor can be easily processed. it can.

Further, if a cooling hole is provided in the rotor so that the cooling fluid flows in from the discharge side rotor shaft end and is discharged from the low temperature side rotor shaft, the rotor temperature difference between the suction side and the discharge side can be reduced. Therefore, since the taper amount can be reduced, the change in performance can be reduced even when the rotor temperature distribution changes when the operating condition changes, and stable and high performance can be obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows the shapes of the male rotor 1 and the female rotor 2 in detail, and FIG. 2 shows the tooth shape of one tooth of the tooth portion of the male rotor 1 at right angles to the axis. 3 is shown in FIG.
FIG. 4 is an enlarged view showing the shape of the tip portion of the tooth tip of FIG. 4, and FIG. 4 shows the entire structure of the dry screw compressor and the rotor cooling oil system according to an embodiment of the present invention.

In FIG. 4, the male rotor 1 and the female rotor 2 are rotatably supported by bearings 14, and the casing 13
It is housed so that the respective tooth portions mesh with each other.
A timing gear 15 is provided on the shaft ends of the male rotor 1 and the female rotor 2.
Is mounted, and a small backlash timing is set so that the male rotor 1 and the female rotor 2 mesh with each other in a non-contact manner, and a driving torque is transmitted from the male rotor 1 as a driving example to the female rotor 2. A rotor cooling hole 11 is provided in the center of each of the male rotor 1 and the female rotor 2, and a cooling fluid such as cooling oil is injected from the nozzle 19 into the cooling hole 11 to cool the rotor. A part of the lubricating oil of the bearing 14 and the timing gear 15 is used as the cooling oil, and the oil pump 17
After being sent to the oil cooler 18 by the rotor and cooled, it is injected from the shaft end on the discharge side 10 of the rotor into the rotor cooling hole 11, and after cooling the rotor is discharged from the shaft end on the suction side 9 to the oil tank 16 Return to.

In the operating state of the compressor, air enters from the air intake port provided in the casing 13 from the intake side 9 into the working chamber formed by the teeth of the male rotor 1 and the female rotor 2 and the inner wall of the casing 13, and the It is compressed by rotation and becomes high temperature and high pressure, and is discharged from the discharge side 10 through a discharge port provided in the casing 13. The casing 13 is cooled by the water jacket 20.

In the dry screw compressor, since the discharge air becomes hot due to the heat of compression of air, the rotor is heated by heat transfer with the air. At this time, the temperature of the rotor is higher on the discharge side than on the suction side. Therefore, the amount of thermal deformation gradually increases from the suction side to the discharge side. Therefore, the diameter of the discharge side is made smaller than the diameter of the suction side in advance during molding of the rotor by an amount corresponding to the difference in thermal expansion amount, and the clearance between the rotors during operation is made uniform from the suction side to the discharge side to improve performance. A tip for this is provided on the outer peripheral portion of the taper rotor, and the distance between the tip of the tip and the axial center of the rotor is the same on the suction side and the discharge side. The tip provided on the outer periphery of the rotor has a width extremely smaller than the rotor diameter, and is provided so as to slightly project from the tip of the tooth profile, and even if it contacts the inner wall of the casing due to thermal deformation deflection etc. Therefore, the clearance between the outer circumference of the rotor and the casing is kept to a minimum during operation. For example, the width of the tip is about 0.5 mm, and the height of the tip from the tip of the tooth profile is about 0.2 mm. The amount of elastic deformation of the rotor during operation (radial direction at the center of the rotor)
Is estimated to be about 1 / 10,000 of the total rotor length. The clearance between the outer circumference of the rotor and the casing cannot be determined only by thermal deformation of the rotor. Factors will influence, but as the chip wears out according to the actual operating condition,
The clearance between the outer circumference of the rotor and the inner wall of the casing is maintained optimally, leakage of air passing through the clearance can be minimized, and the performance of the compressor is improved. Further, the tip of the rotor tooth portion may not come into contact with the rotor casing, and a sufficient taper amount can be obtained. The rotor and the tip may be made of different materials. For example, the material of the tip may be a material that is more easily worn than the rotor and the casing.

FIG. 1 shows a male rotor 1 and a female rotor 2 shown in FIG.
The shape of the rotor will be described in detail.
7 and the tooth bottoms 5 and 8 are machined so as to taper from the suction side 9 toward the discharge side 10.
The distance between the tip of the rotor and the axis of the rotor is 1
0 is the same.

FIG. 2 shows the tooth shape of one tooth of the male rotor 1 at right angles to the axis. In the figure, the broken line shows the discharge side tooth profile 12a at the room temperature, and the solid line the suction side tooth profile. 12b
Indicates. Since the distance between the tip of the tip 3 and the axial center of the rotor is the same for the discharge side tooth profile 12a and the suction side tooth profile 12b,
The height of the tip 3 from the tooth tip is higher in the discharge side tooth profile 12a than in the suction side tooth profile 12b.

FIG. 3 is an enlarged view showing the shape of the tip portion of the tooth tip of FIG.

In the operating state of the compressor, the air temperature rises as it is compressed from the suction side 9 to the discharge side 10, and therefore the temperature of the rotor is also transferred from the suction side 9 to the discharge side by heat transfer from this air. It goes up to 10. In the present embodiment, the rotor temperature under various operating conditions such as the loaded operation and the unloaded operation of the compressor is obtained, the maximum rotor temperature is obtained for each of the suction side 9 and the discharge side 10 of the rotor tooth portion, and the maximum rotor temperature for the room temperature state The amount of thermal expansion is set as the amount of cutter pushing in of the rotor tooth portion, and the amount of cutter pushing in is linearly changed from the suction side 9 to the discharge side 10 to process the tooth portion. At this time, the tip 3 is provided on the outer periphery of the tooth portion and separately processed so that the distance between the tip of the tip 3 and the axial center of the rotor is the same on the suction side 9 and the discharge side 10. The distance between the tip of the tip 3 of one of the rotors and the axial center of the rotor is such that it does not come into contact with the bottom of the mating rotor. Further, the inner diameter of the rotor housing portion of the casing 13 is determined by the thermal expansion of the rotor during compressor operation,
Considering the elastic deformation due to the residual unbalance of the rotor, the radial play of the bearing 14 and the elastic deformation amount, it is determined so that the teeth do not come into contact and the tip 3 is not completely worn.

By using the rotors as described above, the minimum clearance between the male rotor 1 and the female rotor 2 is maintained from the suction side 9 to the discharge side 10 while the compressor is operating, and the outer circumference of each rotor is kept. The clearance of the inner wall of the casing 13 can form a minimum clearance by abrading the chips.

In this embodiment, the suction side 9 and the discharge side 10
Although the difference between the tip diameter and the root diameter of the tooth portion between the two is constant and changed linearly, the difference between the tip diameter and the root diameter changes in the rotor axial direction, and the change in each diameter is Instead of being linear, the shape may be close to the axial temperature curve of the rotor.

[0027]

According to the present invention, the following effects can be obtained.

(A) Since the clearance between the rotor and the clearance between the rotor and the casing can be optimally maintained in the operating state, air leakage from the clearance can be reduced and the performance can be improved.

(B) By making the difference between the tip diameter of the rotor and the diameter of the bottom of the rotor the same on the suction side and the discharge side, the rotor can be processed with one kind of cutter, so that the rotor can be manufactured at low cost. it can. Furthermore, if the reduction rate of the root diameter from the suction side to the discharge side is made constant, taper processing can be performed by increasing the amount of the cutter driven in at a constant rate in the axial direction.
The rotor can be easily processed.

(C) By providing cooling holes in the rotor, the difference in rotor temperature between the suction side and the discharge side can be reduced, and the taper amount can be reduced. Therefore, the rotor temperature distribution when operating conditions change It is possible to reduce the change in performance even with a change in, and stable high performance can be obtained.

[Brief description of drawings]

FIG. 1 is an outline view of a screw rotor with a tip according to an embodiment of the present invention.

FIG. 2 is a vertical sectional view of a tooth portion of a male rotor according to an embodiment of the present invention.

FIG. 3 is an enlarged view of the tip portion of FIG.

FIG. 4 is an overall structural diagram of a screw compressor according to an embodiment of the present invention.

[Explanation of symbols]

1 ... Male rotor, 2 ... Female rotor, 3
… Male rotor tip, 4… Male rotor tip,
5 ... Male rotor root, 6 ... Male rotor tip, 7 ... Male rotor tip, 8 ... Female rotor root, 9 ... Suction side, 10 ... Discharge side, 11 ... Rotor cooling hole, 13 ... Casing, 14 ... Bearing ,

Claims (12)

[Claims] 1. In a dry screw fluid machine in which a screw-shaped male rotor and a female rotor are rotatably supported in a casing, and the rotors rotate while meshing with each other without contacting each other, the rotors are elastically deformed during operation. In consideration of the above, the dry screw fluid machine is characterized in that at least one rotor of the both rotors is provided with a tip at a tooth tip, and the tip is formed in consideration of thermal deformation of the tip during operation. 2. A dry screw fluid machine in which a screw-shaped male rotor and a female rotor are rotatably supported in a casing, and the rotors rotate while meshing without contacting each other. The diameter and the root diameter are larger on the low temperature side than on the high temperature side of the rotor during operation,
A tip is provided on the tooth tips of at least one of the two rotors, and the distance between the tip of the tip and the shaft center of the rotor having the tip is constant between the high temperature side and the low temperature side. Screw fluid machinery. 3. A dry screw fluid machine in which a screw-shaped male rotor and a female rotor are rotatably supported in a casing, and the rotors rotate while meshing with each other without making contact with each other. The diameter and the root diameter are larger on the suction side with respect to the discharge side, a tip is provided on the tooth tip of at least one of the rotors, and the distance between the tip of this tip and the axial center of the rotor having this tip is A dry screw fluid machine characterized by being constant between the suction side and the discharge side. 4. A dry screw fluid machine in which a screw-shaped male rotor and a female rotor are rotatably supported by bearings attached to both ends of the rotor, and the rotors rotate while meshing without contacting each other in a casing, The two rotors are formed in consideration of the amount of thermal expansion during operation, tips are provided on at least one rotor tip of the two rotors, and the distance between the tip of the tips and the axial center of the rotor having the tips is A dry screw fluid machine characterized in that at least one of elastic deformation of the rotor during operation, play and elastic deformation of bearings supporting the rotors, and thermal deformation of the inner diameter of the casing is taken into consideration. 5. A dry screw fluid machine in which a screw-shaped male rotor and a female rotor are rotatably supported in a casing, and the rotors rotate while meshing without contacting each other. On the temperature side and the discharge side, the amount of thermal expansion of both rotors is obtained on the basis of the rotor temperature during load operation to form this rotor, and a tip is provided on the tooth tip of at least one of the rotors, and the tip of this tip The dry screw fluid machine characterized in that the distance between the rotor and the shaft center of the tip is constant between the suction side and the discharge side. 6. The method according to claim 3, wherein the difference between the tooth tip diameter and the tooth bottom diameter of the male rotor and the female rotor is constant between the suction side and the discharge side. The dry screw fluid machine described in. 7. The dry according to claim 2, wherein the difference between the tip diameter and the root diameter of the male rotor and the female rotor is constant between the high temperature side and the low temperature side during operation. Screw fluid machinery. 8. The method according to any one of claims 1 to 7, characterized in that both the axial change rate of the tooth tip diameters of the male rotor and the female rotor and the axial change rate of the tooth root diameters are constant. The dry screw fluid machine according to Item 1. 9. A hole penetrating the rotor is provided at an axial center of at least one of the male rotor and the female rotor,
9. The dry screw fluid machine according to claim 1, wherein a cooling fluid is circulated through the hole to cool the rotor. 10. A timing gear is rotatably supported by bearings attached to both ends of the male and female rotors, and the timing gears are provided at one end of both rotors so that the rotors rotate while meshing without contacting each other. In the dry screw fluid machine having a casing for accommodating these devices, the tip diameter and the root diameter of both rotors at room temperature decrease linearly from the suction side to the discharge side, and The difference between the tip diameter of the rotor and the root diameter is constant between the suction side and the discharge side, and tips are provided on the tooth tips of both rotors,
The dry screw fluid machine characterized in that the distance between the tip of this tip and the axis of the rotor is constant between the suction side and the discharge side. 11. The material of the rotor has a linear expansion coefficient of 6 × 1.
The dry screw fluid machine according to any one of claims 1 to 10, wherein the material is 0 to ⁶ / K or less. 12. The dry screw fluid machine according to claim 1, wherein the material of the rotor is stainless steel.