JPH08151986A - Compressor - Google Patents

Abstract

PURPOSE: To attain preventing wearing out a bearing part by arranging a ball bearing in an opposite side of a timing gear, and enabling an inner ring and a rotor shaft of the ball bearing to relatively move in the axial direction, so as to absorb a thermal expansion difference by using the ball bearing. CONSTITUTION: Drive force of an engine, input from a pulley 3, is accelerated in an accelerating gear train 5, to drive an air compressor 9 rotated through a timing gear train 7. Here are slidably loosely fitted an inner ring 63 of a ball bearing 51 of supporting right ends of shafts 39, 45 and each shaft 39, 45, to form a grease chamber 65 and a grease hole 67 in right end parts of the shafts 39, 45, and the grease chamber 65 is charged with grease. When the shafts 39, 45 are rotated, this grease, receiving centrifugal force to pass through the grease hole 67, is supplied to the surface of each shaft 39, 45, to promote sliding between the shafts 39, 45 and the inner ring 63 of the ball bearing 51. Accordingly, even when the temperature of the compressor rises to generate thermal expansion, since thrust force is absorbed, wearing the ball bearing is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw type compressor.

[0002]

2. Description of the Related Art FIGS. 4 and 5 show conventional screw compressors 201 and 203. These are used in superchargers for vehicles.

The screw type compressor 201 shown in FIG. 4 is disclosed in Japanese Utility Model Laid-Open No. 3-110139, and the driving force of the engine is from the input shaft 205 to the timing gear set 20.
The screw rotors 209 and 211 are rotationally driven via 7 to compress the intake air and supply it to the engine. Rotor 20
The shafts 213, 215 of 9, 211 are the timing gear set 20.
It is supported on the compressor casing 221 via a ball bearing 217 on the No. 7 side and a ball bearing 219 on the other side.

The screw type compressor 203 shown in FIG. 5 is referred to as “Preprints 931 199, Academic Conference, Automotive Engineering Society”.
3-5 p. 193 ", FIG. 2 has the same structure as the air compressor described in No. 2, and the shafts 227 and 229 of the screw rotors 223 and 225 are compressed by a ball bearing 233 on the timing gear set 231 side and a roller bearing 235 on the opposite side. It is supported on the casing 237.

Each rotor 209, 211, 223, 225
The shafts 213, 215, 227 and 229 are made of steel, and the compressor casings 221 and 237 are made of aluminum.

[0006]

The temperature of each part of the screw type compressors 201 and 203 rises up to about 150 ° C. However, due to the above material difference, the rotor shaft 21
A difference in thermal expansion occurs between 3, 215, 227, 229 and the compressor casings 221 and 237. In a supercharger using a screw type compressor or a roots type compressor having a long rotor, the difference in thermal expansion becomes large, and the thermal expansion in the thrust direction is caused by the timing gear set 20.
7,231 and ball bearings 217,217,23
Timing gear set 207 constrained by 3, 233, etc.
Ball bearing 21 with weak binding force, not on the 231 side
9. Appears on the roller bearing 235 side.

In the screw type compressor 201, the ball 2 of the ball bearing 219 receives the thrust force.
Since 39 rotates while sliding in the thrust direction, an excessive force is applied to the ball 239, the inner ring 241, and the outer ring 243 to rapidly wear them, and the performance of the device cannot be maintained.

Further, in the screw type compressor 203,
Although the roller bearing 235 is used to release the thrust force due to the difference in thermal expansion to prevent the bearing portion from being worn, the roller bearing 235 is more expensive than the ball bearing.

Therefore, the present invention absorbs the difference in thermal expansion,
An object of the present invention is to provide a compressor which is configured at low cost by using a ball bearing.

[0010]

A compressor of the first invention comprises a rotor housed in a compressor casing and having a convex portion and a concave portion, and a timing gear connected to each rotor and meshing with each other. Of the timing gear set that engages each other without making contact with each other, the first ball bearing arranged between the compressor casing and the rotor shaft on the timing gear set side, and the compressor casing and the rotor shaft on the opposite side of the timing gear set. A second ball bearing, which is disposed between and has an inner ring loosely fitted to the rotor shaft so as to be movable in the axial direction; a grease chamber formed in the rotor shaft and filled with grease; And a grease hole to be supplied to the sliding portion between the rotor shaft and the rotor shaft.

A compressor according to a second aspect of the present invention is characterized in that a grease groove for diffusing grease from the grease hole to the sliding portion is formed on the rotor shaft side or the inner ring side of the sliding portion. Is.

The compressor of the third invention is the compressor according to claim 1 or 2, wherein the grease groove is formed in a spiral shape or a thrust direction.

[0013]

In the compressor of the first aspect of the invention, the inner ring of the second ball bearing arranged on the opposite side of the timing gear set (the direction in which the thrust force due to the difference in thermal expansion escapes) and the rotor shaft can relatively move in the axial direction. In addition to loosely fitting them, a grease chamber and a grease hole are formed in the rotor shaft, and the centrifugal force of the rotor supplies the grease in the grease chamber from the grease hole to the sliding portion between the inner ring and the rotor shaft. The grease is diffused on the surface of the rotor by the grease groove to promote sliding between the inner ring and the rotor shaft.

Therefore, even if the temperature of the compressor rises and thermal expansion in the thrust direction occurs, the thrust force in this case is absorbed by the rotor shaft moving in the thrust direction between itself and the inner ring. Unlike the conventional example, the wear of the ball bearing is prevented and the performance of the compressor is maintained normally.

Further, since the thrust absorbing function is provided, it does not wear even if a ball bearing is used. Therefore, the compressor can be used by using a ball bearing instead of an expensive bearing such as a roller bearing or a needle bearing. The cost can be reduced accordingly.

In the compressor of the second aspect of the invention, since the groove for diffusing the grease in the grease hole to the sliding portion is formed, the grease is smoothly diffused to the sliding portion, the wear of the ball bearing is prevented, and the performance of the compressor is improved. Kept normal.

In the compressor of the third aspect of the present invention, the grease groove is formed, for example, in parallel with the rotor shaft center or in a spiral shape, whereby the rotation of the rotor shaft promotes the grease diffusion effect in the thrust direction, and the lubricating action of the sliding portion. Is improved and the function of absorbing thrust force is improved.

Further, when the rotor shaft is moved, damage to the inner ring and the seal of the ball bearing due to the grease groove is small,
Performance deterioration of the compressor is prevented.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG.
FIG. 1 shows a supercharger 1 using this embodiment. It should be noted that members and the like to which reference numerals are not given are not shown.

As shown in FIG. 1, the supercharger 1 has an input pulley 3,
The speed increasing gear set 5, the timing gear set 7, the screw type air compressor 9 and the like are included.

The input pulley 3 is supported by the compressor casing 13 by a bearing 11 and is spline-connected to the input shaft 15, and the bolt 17 and the washer 1 are connected.
It is fixed at 9 and. The input pulley 3 is connected to a pulley on the crankshaft side via a belt, and is rotationally driven by the driving force of the engine. The input shaft 15 is supported on the casing 13 by a ball bearing 21. A seal 25 is arranged between the sleeve 23 mounted on the input shaft 15 and the casing 13 to prevent oil leakage. The casing 13 is made of aluminum.

The speed-increasing gear set 5 is composed of large-diameter and small-diameter gears 27 and 29 meshing with each other.
Is a large-diameter and small-diameter timing gear 31, which mesh with each other,
It is composed of 33. Further, the air compressor 9 includes male and female screw rotors 35 and 37.

The large-diameter gear 27 of the speed increasing gear set 5 is the input shaft 15
The small-diameter gear 29 is integrally formed with the right end of the, and together with the large-diameter gear 31 of the timing gear set 7, the small-diameter gear 29 is connected to the shaft 39 (rotor shaft) of the screw rotor 37 by the key 41 and fixed by the nut 43. . The small diameter gear 33 of the timing gear set 7 is the shaft 45 (rotor shaft) of the screw rotor 35.
It is fixed by a nut 47 to the. These shafts 39, 45
Is made of steel.

Shafts 45 and 3 of the screw rotors 35 and 37
9 has a ball bearing 49 (first ball bearing) at the left end and a ball bearing 51 (second ball bearing) at the right end.
Ball bearings) and casings 13
Is supported by. A seal 55 is arranged between the sleeve 53 mounted on the left end side of the shafts 39 and 45 and the casing 13, and a seal 57 is arranged between the right end parts of the shafts 39 and 45 and the casing 13. Prevents leakage.

The driving force of the engine input from the pulley 3 is increased in speed by the speed increasing gear set 5 and rotationally drives the air compressor 9 via the timing gear set 7. The timing gear set 7 meshes without contacting the screw rotors 35 and 37. The driven air compressor 9 has a suction hole 59.
The intake air sucked from the engine is pressure-fed in the axial direction between the screw rotors 35 and 37, discharged from the discharge hole 61, and supplied to the engine.

The inner ring 63 of the ball bearing 51 which supports the right ends of the shafts 39 and 45 and the respective shafts 39 and 45 are slidably loosely fitted. Also, as shown in FIG. 1, the shafts 39, 4
A grease chamber 65 and a grease hole 67 are formed at the right end of 5, and the grease chamber 65 is filled with grease. When the shafts 39 and 45 rotate, this grease receives centrifugal force and is supplied to the surfaces of the shafts 39 and 45 through the grease holes 67 to promote sliding between the shafts 39 and 45 and the inner ring 63 of the ball bearing 51.

Next, another embodiment of the present invention will be described with reference to FIGS. This embodiment has the features of the second and third inventions.

In these embodiments, the shafts 81, 83 of the screw rotors 77, 79 are supported by the compressor casing 13 via the ball bearings 51, and the shafts 81, 83
A seal 57 is arranged between 83 and the casing 13. Inner ring 6 of shafts 81 and 83 and ball bearing 51
3 is loosely fitted so as to be slidable. Shaft 81,83
Has a grease chamber filled with grease and a grease hole. The shafts 81 and 83 are made of steel.

In the embodiment shown in FIG. 2, a shaft 81 is provided with a circumferential groove 85, and a spiral grease groove 87 is formed between the circumferential groove 85 and the shaft end. The surface of the shaft 81 that contacts the seal 57 is smooth. The rotation of the spiral grease groove 87 causes the grease to spread widely in the circumferential direction and the thrust direction of the shaft 81, making the shaft 81 and the inner ring 63 easier to slide.

Further, in the embodiment shown in FIG. 3, the shaft 83 has a circumferential groove 8 formed therein.
9 is provided, and a grease groove 91 in the thrust direction parallel to the rotor axis is provided between the circumferential groove 89 and the shaft end. The surface of the shaft 83 that contacts the seal 57 is smooth. Due to the grease groove 91 in the thrust direction, the grease is widely spread in the circumferential direction of the shaft 83 and in the thrust direction.
And the inner ring 63 are made to slide more easily. Grease groove 9
Since 1 is formed in the thrust direction, the inner ring 63 is less damaged by the grease groove 91 when the shaft 83 is moved, and the performance deterioration of the air compressor is prevented.

As described above, since the embodiments shown in FIGS. 2 and 3 have the thrust force absorbing function, the difference in thermal expansion between the casing 13 and the shafts 81 and 83 due to the material difference is caused by the temperature rise of the air compressor. Even if it occurs, the thrust force due to this thermal expansion difference is absorbed by the shafts 81 and 83 moving in the thrust direction with respect to the inner ring 63, and unlike the conventional example of FIG. 51 does not wear, and the performance of the air compressor is kept normal. Therefore, the air compressor can be constructed at low cost by using ball bearings instead of expensive bearings such as roller bearings and needle bearings.

In addition to this, the shaft 8 in contact with the seal 57
Since the surfaces of Nos. 1 and 83 are smooth, even if the shafts 81 and 83 rotate at high speed, the seal 57 is not galled.

By providing such a thrust force absorbing function, unlike the conventional example shown in FIG. 4, the ball bearing 51 is not worn even if a difference in thermal expansion occurs, and the performance of the compressor is kept normal. Therefore, the supercharger 1 can be constructed at a low cost by using a ball bearing instead of an expensive bearing such as a roller bearing or a needle bearing.

Further, in the screw type compressor, which has an internal compression action and is used at a high rotation speed and a high supercharging pressure like the air compressor 9, since a large amount of heat is generated, a thrust force due to a difference in thermal expansion appears remarkably. The thrust absorbing function according to the invention is particularly effective.

Thus, the supercharger 1 is constructed.

The grease groove is not limited to a spiral groove or a groove parallel to the rotor axis, and may have any shape.

Further, even in a roots type compressor having a rotor of cocoon type cross section, even if the rotor is long, the thrust force problem due to the difference in thermal expansion occurs, so the thrust force absorbing function of the present invention is effective. .

The present invention has been described above. However, the number of grease holes is not limited to one, and if a plurality of grease holes are formed, a larger amount of grease can be expected to be introduced. Instead, it may be formed on the inner circumference of the bearing inner race.

[0039]

In the compressor of each invention, the inner ring of the second ball bearing arranged on the opposite side of the timing gear set and the rotor shaft are loosely fitted so as to be capable of relative movement in the axial direction, and centrifugal force is applied. While supplying grease from the rotor grease chamber between the inner ring and the rotor shaft,
The grease is diffused on the surface of the rotor by the grease groove to promote sliding between the inner ring and the rotor shaft.

Therefore, the thrust force due to the difference in thermal expansion is absorbed by the movement of the rotor shaft in the thrust direction,
The wear of the ball bearings is prevented and the performance of the compressor is kept normal.

By virtue of such thrust absorbing function, the compressor can be constructed at low cost by using ball bearings instead of expensive bearings such as roller bearings and needle bearings.

In the compressor of the second aspect of the present invention, since the grease groove for diffusing from the grease hole to the sliding portion is formed in either the rotor shaft or the bearing inner ring which is the sliding portion, the grease is smoothly diffused in the sliding portion. The wear of the ball bearings is prevented and the performance of the compressor can be kept normal.

In the compressor of the third aspect of the invention, since the grease groove is formed in the thrust direction, the rotation of the rotor shaft promotes the grease diffusion effect, and the thrust force absorbing function is improved.

Further, when the rotor shaft is moved, the grease groove does not damage the inner ring of the ball bearing or the seal, and the performance of the compressor can be kept normal for a long period of time.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part showing another embodiment of the present invention.

FIG. 3 is an enlarged view of an essential part showing another embodiment of the present invention.

FIG. 4 is a sectional view of a conventional example.

FIG. 5 is a cross-sectional view of another conventional example.

[Explanation of symbols]

 7 Timing Gear Set 9 Screw Type Air Compressor 13 Compressor Casing 31, 33 Timing Gear 35 Screw Rotor (Male Type) 37 Screw Rotor (Female Type) 39, 45, 81, 83 Shaft (Rotor Shaft) 49 First Ball Bearing 51 Second ball bearing 63 Inner ring 65 Grease chamber 67 Grease hole 87,91 Grease groove 77,79 Screw rotor

Claims (3)

[Claims] 1. A timing gear set comprising a rotor housed in a compressor casing, each having a convex portion and a concave portion, and a timing gear connected to each rotor and meshing with each other, wherein the convex gear portion and the concave portion mesh with each other without contacting each other. ,
A first ball bearing arranged between the compressor casing and the rotor shaft on the timing gear set side, and arranged between the compressor casing and the rotor shaft on the opposite side of the timing gear set, the inner ring of which is arranged on the rotor shaft. A second ball bearing that is loosely fitted so that it can move in any direction;
A compressor, comprising: a grease chamber formed in a rotor shaft and filled with grease; and a grease hole that receives a centrifugal force and supplies the grease to a sliding portion between the inner ring and the rotor shaft. 2. The compressor according to claim 1, wherein a grease groove for diffusing grease from the grease hole to the sliding portion is formed on the rotor shaft side or the inner ring side of the sliding portion. 3. The compressor according to claim 1, wherein the grease groove is formed in the thrust direction.