JPH05133360A - Nonlubricated screw compressor - Google Patents

Abstract

PURPOSE:To prevent a thrust bearing from bearing a radial load by providing a spring of coil spring, belleville spring, etc. between the thrust bearing and a bearing retainer or in both sides of the thrust bearing, and fixing the thrust bearing by spring tension. CONSTITUTION:A compressor provides male/female rotors 1, 2 meshed with each other, casing 3 for storing both the rotors, radial bearings 5a, 5b for supporting both the rotors, thrust bearings 6, 6a, 6b and bearing retainers 13a, 13b for fixing both the bearings. A coil spring 16 is provided between the thrust bearings 6, 6a, 6b and the bearing retainers 13a, 13b to fix the thrust bearings 6, 6a, 6b by spring tension. Further, the coil spring 16 is arranged concentrically in a plural quantity. In this way, the thrust bearings 6, 6a, 6b can be prevented from bearing a radial load, and a circular part clearance can be prevented from decreasing due to deformation of a thrust bearing outer ring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing fixing structure for a screw type compressor such as an oilless screw compressor.

[0002]

2. Description of the Related Art A prior art related to a bearing fixing device for an oilless compressor is disclosed in Japanese Patent Laid-Open No. 61-103013, in which a plate for fixing an outer ring of an angular bearing is provided with a spigot and an outer ring of the bearing is assembled. It prevents the unbalanced load from acting on.

In this prior art, the plate for fixing the outer ring of the thrust bearing, that is, the bearing retainer is fixed by means of several tightening bolts to fix the thrust bearing. In this case, a force proportional to the tightening torque for tightening the bolt is used. Acts on the end face of the thrust bearing outer ring. Therefore, if the tightening torque is large, the frictional force on the end surface of the outer ring of the thrust bearing will be large, and the thrust bearing will not be able to slide against the gas load perpendicular to the rotor axis, that is, the radial load, and the thrust bearing will bear the radial load. Will be done. Further, in this case, the compressive force acting on the outer ring of the thrust bearing becomes large, the amount of deformation of the outer ring of the thrust bearing becomes large, the internal clearance thereof decreases, and the life of the bearing is shortened. Further, when the tightening torque of each bolt is not constant and varies, the bearing retainer is likely to be in a partially tightened state, which may reduce the internal clearance of the thrust bearing and increase the misalignment with respect to the bearing mounting position.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to prevent a thrust bearing from bearing a radial load, and
The purpose of this is to prevent the reduction of the internal clearance due to the deformation of the outer ring of the thrust bearing and to prolong the life of the thrust bearing. Further, it is to prevent the bearing retainer from being in a partially tightened state, and to prevent the internal clearance of the thrust bearing from decreasing and misalignment with respect to the bearing mounting position to increase.

[0005]

To achieve the above object, the present invention fixes a male rotor, a female rotor, a casing accommodating both rotors, a radial bearing supporting both rotors, a thrust bearing, and both bearings, which mesh with each other. In an oil-free screw compressor composed of a bearing retainer, etc., a spring such as a coil spring or a flat spring is provided between the thrust bearing and the bearing retainer or on both sides of the thrust bearing, and the thrust bearing is supported by the spring force. To fix.

[0006]

When the thrust bearing is fixed by the spring force, the desired bearing outer ring tightening force can be obtained by appropriately selecting the spring constant, the deflection, and the number of arrangements. On the other hand, on the end surface of the thrust bearing outer ring, a sliding friction force proportional to the bearing outer ring tightening force is generated. If the bearing outer ring tightening force is determined so that the radial load becomes larger than this sliding frictional force, the thrust bearing can slide in the radial load direction, the radial bearing bears the radial force, and the thrust bearing only has the thrust force. Works.

Next, when the thrust bearing is fixed by using steel balls, rolling frictional force is generated on the end surface of the outer ring of the thrust bearing. Since the rolling frictional force is sufficiently smaller than the sliding frictional force, it is possible to cause the thrust bearing to slide in the radial load direction even with a large bearing outer ring tightening force.

Next, when the thrust bearing is fixed by the spacer coated with the fixed lubricating coating agent, the friction coefficient of the solid lubricating coating agent can be reduced. Therefore, the thrust bearing can slide in the radial load direction even with a relatively large bearing outer ring tightening force.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. Male rotor 1 and female rotor 2 that mesh with each other
Is stored in the casing 3 and the S casing 4,
Further, the male rotor 1 and the female rotor 2 respectively have cylindrical roller bearings 5a and 5b and a combination angular bearing 6 on the discharge side.
a, 6b, and the suction side is supported by cylindrical roller bearings 7a, 7b. A pinion gear 8 is fitted to the suction side shaft end of the male rotor 1, a timing gear 9a is fitted to the discharge side shaft end, and a timing gear 9b is fitted to the discharge side shaft end of the female rotor 2.

The shaft power transmitted to the pinion gear 8 causes the male rotor 1 to rotate, and further the two pairs of timing gears 9
The female rotor is synchronously rotated via a and 9b. As a result, the lobe portion 1a of the male rotor 1 and the lobe portion 2a of the female rotor 2 maintain a small clearance and rotate synchronously, and the suction port 10
The air drawn in from the outlet is boosted to a specified pressure
It is discharged from 1.

When the male rotor 1 and the female rotor 2 rotate to compress the air, a gas load perpendicular to the rotor axial direction, that is, a radial force, is applied to each of the male rotor 1 and the female rotor 2, so that the rotor is sucked in the axial direction. A gas load or thrust force that pushes in acts. The bearings provided for bearing the radial force acting on the rotor are cylindrical roller bearings 5a and 5b.
The bearings provided for bearing the thrust force are the combination angular bearings 6a and 6b. In the discharge side bearing portion, the cylindrical roller bearing 5, the oil supply spacer 12 for supplying lubricating oil to the bearing, and the combination angular bearing 6 are arranged in this order, and the bearing retainer 13 is provided on the outer ring side surface of the combination angular bearing 6, The structure is such that the cylindrical roller bearing 5, the oil supply spacer 12, and the combined angular bearing 6 are fixed by tightening with several bolts 14. Incidentally, the cylindrical roller bearing 5, the refueling spacer 12
Are fitted to the casing 3 by an interference fit or an intermediate fit, and the combined angular bearings 6 are fitted by a clearance fit. Further, a spigot portion is provided in a portion where the casing 3 and the bearing retainer 13 are adjacent to each other, so that when the compressor body is assembled,
The bearing retainer 11 is prevented from moving and an unbalanced load does not act on the outer ring of the combined angular bearing 6.

The above is the same as the configuration and operation of the prior art. In this embodiment, a coil spring 16 and a spacer 17 are further provided between the bearing retainer 13 and the combined angular bearing outer ring 15. Bearing clamp end face 1
Each bearing is fixed via the coil spring 16 by tightening until 3a contacts the casing end surface 18.
A plurality of coil springs 16 are arranged concentrically.

The desired bearing outer ring tightening force can be obtained by appropriately selecting the spring constant, the deflection, and the arrangement quantity of the coil spring 16. On the other hand, a sliding frictional force proportional to the bearing outer ring tightening force is generated on the combined angular bearing outer ring end surface 18. Therefore,
If the bearing outer ring tightening force is determined so that the radial load becomes larger than this sliding frictional force, the combined angular bearing can slide in the radial load direction, and the combined angular bearing 6
The radial force does not act on, but only the thrust force acts on.

On the other hand, when a helical gear is used as the pinion gear 8, when the compressor is started, a reverse thrust force that pushes the rotor toward the discharge side acts on the male rotor 1 in proportion to the starting torque.
If this thrust force is larger than the bearing outer ring tightening force, the male rotor 1 is displaced so that the discharge end face gap becomes smaller and there is a possibility of contact between the discharge end faces. A coil spring or the like is configured to be large.

With this structure, when the compressor is in operation, the combined angular bearing does not act on the radial force but only the thrust force, so that the life of the combined angular bearing can be significantly increased. ..

In the prior art, as shown in FIG. 3, the bearing retainer is tightened with several tightening bolts 14 to fix each bearing, but the bearing retainer end face 18 does not contact the casing end face.
The bearing outer ring tightening force is proportional to the tightening torque of the bolt 14.
Therefore, when the tightening torque increases, the load transmitted to the casing 3 via the bearing outer ring also increases, and the amount of deformation inside the casing 3 also increases. Further, when the bolt tightening torque increases, the amount of deformation of the combined angular bearing outer ring 18 increases, and the internal clearance decreases. Further, when the tightening torque of each bolt 14 varies, an unbalanced load acts on the combined angular bearing outer ring 18, and the internal clearance thereof may decrease and misalignment with respect to the bearing position may increase.

In this embodiment, by fixing the combined angular bearing through a plurality of coil springs, the surface pressure on the side surface of the bearing outer ring becomes uniform, and it is possible to prevent an unbalanced load from acting on the combined angular bearing outer ring. Therefore, it is possible to prevent a decrease in the internal clearance of the combined angular bearing and an increase in misalignment with respect to the bearing mounting position. Further, the bearing outer ring tightening force becomes constant regardless of the bolt tightening torque, and the value of this tightening force can be reduced, so that the amount of deformation inside the casing can be reduced, and the bearing clearance can be prevented from decreasing due to the bearing outer ring deformation. be able to.

Next, a second embodiment of the present invention will be described with reference to FIG. This embodiment uses a flat spring 19 instead of the coil spring in the first embodiment, and the operation and effect are the same as those in the first embodiment. When using flat springs, the number is at least one, which simplifies the structure and improves assembly.

Next, a third embodiment will be described with reference to FIG.
In this embodiment, steel balls are used in place of the springs such as coil springs and flat springs in the first and second embodiments. From the compressor suction side, cylindrical roller bearing 5, refueling spacer 1
2, the spacer 21a for holding the steel ball, the steel ball 20, the combined angular bearing 6, the spacer 21b, the steel ball 20, and the bearing retainer 13 are arranged in this order, and the entire structure is fixed by the fixing screw 22. A plurality of steel balls 20 are concentrically arranged.

In such a structure, rolling friction force proportional to the bearing tightening force is generated in the spacers 21 on both sides of the combined angular bearing 6. In this case, since the rolling frictional force is sufficiently smaller than the sliding frictional force, the frictional force can be made smaller than the radial force even for a large bearing tightening force,
The combined angular bearing 6 can slide together with the spacer 21 in the radial load direction. The compressive stress generated in the steel ball, that is, the Hertz stress value is set within the allowable value. As a result, when the compressor is in operation, the combined angular bearing does not act on the radial force but only the thrust force, and the life of the combined angular bearing can be significantly increased.

Next, a fourth embodiment will be described with reference to FIG. In this embodiment, a thrust ball bearing is used instead of the steel balls and the spacer of the third embodiment. From the compressor suction side, the cylindrical roller bearing 5, the oil supply spacer 12, the thrust ball bearing 23, the combination angular bearing 6, Thrust ball bearing 23, bearing retainer 1
It is arranged in the order of 3, and the whole structure is fixed by the fixing screw 22. Further, a thrust ball bearing is selected so that the thrust ball bearing 23 shaft fitting portion has a gap with respect to each rotor 1, 2.
The bearing tightening force should be less than the static load rating of the thrust ball bearing. The action and effect are similar to those of the third embodiment. In this case, when assembling the compressor body, if the thrust ball bearing in the assembled state (commercially available) is used, the assemblability is improved as compared with the third embodiment.

Next, a fifth embodiment will be described with reference to FIG.
In this embodiment, instead of the coil spring in the first embodiment, a spacer having a solid lubricant coating agent applied on one side is used. From the suction side of the compressor body, the cylindrical roller bearing 5, the oil supply spacer 12, the spacer 24a, the combined angular bearing 6, the spacer 24b, and the bearing retainer 13 are arranged in this order, and the stop screw 22
The whole structure is fixed with. Spacers 24a, 25b
Solid lubricant coating agent 2 on the surface in contact with angular bearing 6
Apply 5. As the solid lubricating coating agent, for example, CFC metal is used. Since the friction coefficient of the solid lubricant coating agent can be made small, the frictional force at the outer surface of the outer surface of the combined angular bearing becomes small. Therefore, the radial force can be made larger than the frictional force even with a relatively large bearing outer ring tightening force. Therefore, when the compressor is in operation, no radial force acts on the combined angular bearings, but only thrust force acts, and the life of the combined angular bearings can be significantly increased.

Next, a sixth embodiment will be described with reference to FIG.
This embodiment is an improvement of the fifth embodiment, in which a spacer coated with a solid lubricant coating agent on one side is arranged only on the bearing holding side with respect to the combined angular bearing. From the suction side of the compressor body, the cylindrical roller bearing 5, the oil supply spacer 12, the combined angular bearing 6, the spacer 24 coated with the solid lubricant coating agent 25 on one side, and the bearing retainer are arranged in this order, and the spacer tightening bolt 26 is used to The structure is to fix. Further, a mechanism is provided to prevent the spacer tightening bolt 26 from loosening. As an example of this loosening prevention, the set screw 27 is used in the present embodiment, but it is also possible to apply an adhesive for screw fixing to the thread portion of the spacer tightening bolt to fix it. In the case of this structure, the combined angular bearing outer ring tightening force and the combined angular bearing outer ring end face friction force are proportional to the tightening torque of the spacer tightening bolt. Therefore, the tightening torque of the spacer tightening bolt is controlled so that the frictional force becomes smaller than the radial load. The smaller the tightening torque, the easier the combined angular bearing slips with respect to the radial load, but the spacer tightening bolt may loosen. If the spacer tightening bolt becomes loose, the entire combined angular bearing moves relative to the casing, possibly causing rotor contact. In this embodiment, since the tightening bolt loosening prevention mechanism is provided, the combined angular bearing can slide with respect to the radial load without causing this problem.

[0024]

According to the present invention, the radial load is not applied to the thrust bearing, the internal clearance is prevented from decreasing due to the deformation of the outer ring of the thrust bearing, and the life of the thrust bearing can be extended. Further, it is possible to prevent the bearing retainer from being in a partially tightened state, and to prevent the internal clearance of the thrust bearing from decreasing and the misalignment with respect to the bearing mounting position from increasing.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an oil-free screw compressor showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the discharge side shaft portion of FIG.

FIG. 3 is a cross-sectional view of a discharge side shaft portion of a conventional oil-free screw compressor.

FIG. 4 is a sectional view of a discharge side shaft portion of an oilless screw compressor according to a second embodiment.

FIG. 5 is a sectional view of a discharge side shaft portion of an oil-free screw compressor showing a third embodiment.

FIG. 6 is a sectional view of a discharge side shaft portion of an oil-free screw compressor showing a fourth embodiment.

FIG. 7 is a sectional view of a discharge side shaft portion of an oil-free screw compressor showing a fifth embodiment.

FIG. 8 is a sectional view of a discharge side shaft portion of an oil-free screw compressor showing a fifth embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Male rotor, 2 ... Female rotor, 3 ... Casing, 5 ... Cylindrical roller bearing, 6 ... Combination angular bearing, 13 ... Bearing retainer, 16 ... Coil spring.

Claims (1)

[Claims] 1. A male rotor and a female rotor which mesh with each other, a casing for housing the male rotor and the female rotor, a radial bearing for supporting the male rotor and the female rotor,
In an oil-free screw compressor composed of a slight bearing and a bearing retainer for fixing the radial bearing and the thrust bearing, a spring is provided between the thrust bearing and the bearing retainer or on both sides of the thrust bearing. An oil-free screw compressor in which the thrust bearing is fixed.