JPH0849554A - Biaxial supercharger - Google Patents

Abstract

PURPOSE:To suppress the distance change between bearing coupling sections and improve durability by integrally inserting a spectacle-like bearing support member into a casing when bearings supporting the shafts of a pair of male and female rotors are coupled with the casing. CONSTITUTION:A pair of male and female rotors 11, 13 having screw-like teeth are arranged in the rotor casing 3 of a screw type supercharger to be meshed in no contact with each other at a gap. The rotors 11, 13 are formed integrally with rotor shafts 15, 17, and both end sections of the rotors 11, 13 are rotatably supported by the bearings 25a, 15b of a bearing section 23 and the bearings 21a, 21b of a bearing section 19. The bearing section 19 is made of a low- expansion member, and a bearing support member 27 formed with a pair of bearing coupling sections 29, 29 into a spectacle-like shape via a junction 31 to be coupled with the bearings 21a, 21b is integrally inserted into the rotor casing 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a twin-screw supercharger for supercharging, for example, an automobile engine.

[0002]

2. Description of the Related Art As a conventional two-shaft type supercharger of this type,
For example, FIG. 4 described in Japanese Patent Laid-Open No. 2-153285.
There is something like the screw type supercharger shown in.

This screw type turbocharger has a casing 1
01, a pair of female and male rotors 103 and 105 having screw type teeth are meshed with each other, and both end portions of rotor shafts 107 and 109 integrated with the rotors 103 and 105 are constituted by ball bearings or the like. Bearings 111,1
It is rotatably supported by 13, 115, 117.

Timing gears 119 and 121, which overhang the discharge sides of the rotors 103 and 105, are provided on the rotor shafts 107 and 109, respectively, in a chamber 123 defined by a bearing casing 101a which is a partition wall. There is. The timing gears 119 and 121 are meshed with each other with a very small backlash.

Further, a small gear 125 of a speed increasing gear is provided at the tip of the timing gear 119 of the female rotor shaft 107, and this small gear 125 is a speed increasing gear provided at one end of the input shaft 127. It is meshed with the large gear 129.

The input shaft 127 is rotatably supported by the casing 101 via a bearing 131 composed of a ball bearing or the like, and a pulley 133 is provided at the other end thereof.

When a rotational force is input from the engine to the pulley 133, the rotational force is transmitted from the pulley 133 to the input shaft 127 and is increased by the speed increasing gears 129 and 125 to the female rotor 103 via the female rotor shaft 107. And transmitted from the female rotor shaft 107 to the timing gears 119, 12
1 and the male rotor shaft 109 to be transmitted in synchronization with the male rotor 105.

Then, a pair of male and female rotors 103, 105
Rotates while meshing with each other without coming into contact with the casing 101, and the air sucked from the suction side is compressed by the rotors 103 and 105 and discharged from the discharge side to supercharge the engine.

In the screw type supercharger having such a structure, the casing 101 is generally made of an aluminum material to reduce the weight.

[0010]

By the way, in such a screw type supercharger, an extremely large temperature difference occurs between the suction side and the discharge side of the rotor during operation, for example, 20 to 30 on the suction side. While the temperature is normal temperature of ℃, it becomes as high as about 180 ℃ on the discharge side.

On the other hand, since there is a difference in thermal expansion between the aluminum material and the iron material, when the iron bearing is fitted in the aluminum casing, the aluminum casing is better than the iron bearing at high temperature. Since the thermal expansion is large, the bearing fitting hole of the casing also extends in the radial direction, and a gap is created between the bearing and the outer ring of the bearing, so that the fitting of the both is loosened, causing play, and slipping between them.

Therefore, in the screw type supercharger as described above. During operation, the suction side of the rotors 103 and 105 has a normal temperature and the discharge side has a high temperature, so that the thermal expansion of the casing 101 on the discharge side with respect to the suction side increases, and the casing
01 bearing fitting hole and ball bearing 111, 1
A gap is formed between the rotor shaft 107 and the rotor shaft 13 and the rotor shafts 107 and 109 supported by the ball bearings 111, 113, 115 and 117 are tilted.

When both rotor shafts 107 and 109 are tilted, the axial distance between the timing gears 119 and 121 changes, and the backlash changes accordingly. Therefore, the meshing noise of the timing gears 119 and 121 changes. Becomes larger, which in turn lowers the durability.

Further, since the rotors 103 and 105 also incline with the inclination of the rotor shafts 107 and 109, both rotors 10 and
3, 105 may come into contact with each other, and galling may occur.

Therefore, according to the present invention, the bearings for supporting the respective shafts of the pair of male and female rotors are fitted in the casings made of different materials, but the change in the axial distance between the rotor shafts due to the difference in thermal expansion is suppressed. The purpose of the present invention is to provide a twin-screw supercharger that can perform

[0016]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention has a structure in which a bearing supporting each shaft of a pair of male and female rotors is fitted in a casing made of a different material, A two-shaft turbocharger in which a timing gear meshing with each other is provided, and the air sucked from the suction side by the rotation of the rotor is pressure-fed and discharged from the discharge side, and a low expansion is provided at least on the discharge side of the casing. A pair of bearing fitting portions formed of a member, which fits the bearings, and a bearing supporting member in the shape of a spectacle, which is formed by connecting both bearing fitting portions with a connecting portion, is integrated by casting. It has a feature.

[0017]

Even if the casing has a larger thermal expansion than the bearing support member, the change in the distance between the bearing fitting portions is suppressed, and the fitting between the bearing fitting portion and the bearing does not loosen. A change in inter-axis distance between axes is suppressed.

As a result, the change in the backlash of the timing gear is suppressed, the meshing noise of both gears can be reduced, and the durability of the gear is improved.

Further, the inclination of the rotor due to the difference in thermal expansion is suppressed, the gap between the rotors can be kept minute, and the performance can be improved.

[0020]

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

FIG. 1 is a front sectional view of a screw type supercharger as a two-shaft type supercharger according to an embodiment of the present invention.

The casing 1 is composed of a rotor casing 3, a gear casing 5 and left and right covers 7 and 9 which are made of an aluminum material, and is configured to be axially separable.

In the rotor casing 3, a pair of male and female rotors 11 and 13 having screw-shaped teeth are arranged in mesh with each other with a slight clearance so as not to contact the rotor casing 3 and each other.

The rotors 11 and 13 integrally have rotor shafts 15 and 17, respectively, and both ends of the rotor shafts 15 and 17 are bearings 21a and 21b of a bearing portion 19 provided in the rotor casing 3, and gears. It is rotatably supported via bearings 25a and 25b of a bearing portion 23 provided in the casing 5.

The bearing portion 19 is integrally formed by casting a bearing support member 27 formed of a material having a small thermal expansion (low expansion member), for example, an iron material, in the rotor casing 3.

The bearing support member 27, as shown in FIG.
A pair of bearing fitting portions 29 into which the bearings 21a and 21b can be fitted are provided at both ends, and both fitting portions 29 are connected by a connecting portion 31 to form a pair of glasses.

The bearings 21a and 21b are needle bearings or the like.

The bearing portion 23 is formed integrally with the gear casing 5 by casting a bearing support member 33 formed of a material having a small thermal expansion (low expansion member), for example, an iron material.

The bearing support member 33, as shown in FIG.
It has a pair of bearing fitting portions 35 capable of fitting the bearings 25a and 25b at both ends, and is formed into a spectacle shape in which both fitting portions 35 are connected by a connecting portion 37.

The bearings 25a and 25b are ball bearings or the like.

The rotor casing 3 includes rotors 11, 1
A suction port (not shown) for sucking air by the rotation of the rotors 11 and 13 is formed on one end side (bearing 21a, 21b side in FIG. 1) of 3 and the other end side (bearing 25a, 25b side in FIG. 1). ) Is a discharge port (not shown) for discharging the compressed air pressure-fed by the rotation of the rotors 11 and 13.
Are formed.

Rotor shafts 15 and 17 of the rotors 11 and 13
One end side (bearing 25a, 25b side in FIG. 1) of the rotor is overhung in the gear casing 5, and the female rotor shaft 15 is provided with a timing gear 39 and a small gear 41 as a speed increasing gear by a key 43 and a nut 45. It is fixed. Meanwhile, the timing gear 39 is attached to the male rotor shaft 17.
The timing gear 47 that meshes with the backlash is extremely small is fixed by the reamer pin 49 and the nut 51.

The small gear 41 is meshed with a large gear 55 as a speed increasing gear provided at one end of the input shaft 53.

The input shaft 53 is rotatably supported by the cover 7 via a bearing 57 composed of a ball bearing or the like, and an input pulley 59 is attached to the other end by a bolt 61.

The input pulley 59 has a cover 63 and a bolt 63.
Is rotatably supported integrally with the input shaft 53 through a bearing 67 composed of a ball bearing or the like on a support member 65 attached by.

Next, the operation of the screw type supercharger according to the above embodiment will be described.

When a rotational force is input to the input pulley 59 from an engine (not shown), the input shaft 59 is fed from the input pulley 59.
Is transmitted to the large gear 55 via, and further transmitted from the large gear 55 to the small gear 41 to be accelerated.

When the large gear 55 rotates in the clockwise direction, the small gear 41 meshing with the large gear 55 rotates in the counterclockwise direction, and the female rotor 11 is rotated counterclockwise from the small gear 41 via the female rotor shaft 15. Rotate to.

At the same time, since the timing gear 39 also rotates counterclockwise, the timing gear 47 meshing therewith rotates clockwise, and the male rotor 13 is synchronized with the female rotor 11 from the timing gear 47 via the male rotor shaft 17. And rotate clockwise.

The pair of male and female rotors 11 and 13 are
The rotor casing 3 and the rotor casing 3 rotate while meshing with each other without coming into contact with each other, and the air sucked from the suction port (not shown) is compressed by the rotors 11 and 13 and discharged from the discharge port to supercharge the engine.

When the rotors 11 and 13 are rotationally driven in this way, the temperature on the discharge side of the rotors 11 and 13 rises to a high temperature (about 180 ° C.).

At high temperature, a gap is created between the gear casing 5 made of an aluminum material and the bearing support member 33 made of an iron material due to a difference in thermal expansion between them, but the bearing support member 33 is made of an iron material which is a low expansion member, Since the pair of fitting portions 35 are connected by the connecting portion 37, the change in the distance between the fitting portions 35 due to thermal expansion is small. Further, since the bearings 25a and 25b fitted in the fitting portion 35 are also made of an iron material which is a low expansion member, there is no difference in thermal expansion between the bearing support member 33 and the bearings 25a and 25b. The fitting does not loosen.

Therefore, the change in the axial distance between the rotor shafts 15 and 17 supported by the bearings 25a and 25b is suppressed.

As a result, the change in the backlash of the timing gears 39 and 47 provided on the rotor shafts 15 and 17 is suppressed, so that the meshing noise of both gears 39 and 47 is reduced and the durability thereof is improved. .

Further, since the rotors 11 and 13 are not tilted, the gap between the rotors 11 and 13 can be kept small and the performance can be improved. The same effect can be obtained by applying the present invention to a two-axis roots type supercharger.

[0046]

As is apparent from the above description, according to the present invention, when the bearings for supporting the respective shafts of the pair of male and female rotors are fitted in the casing made of different materials, the casing is made to have a low Since the spectacle-shaped bearing support member formed of the expansion member is cast around and integrated, and the bearing is fitted to the bearing fitting portion provided on the bearing support member, the casing is expanded more thermally than the bearing support member. Even if it is large, the change in the distance between the bearing fitting portions is suppressed, and since the fitting between the bearing fitting portion and the bearing does not loosen, the change in the axial distance between both rotor shafts is suppressed. . As a result, the change in the backlash of the timing gear is suppressed, it is possible to prevent an increase in the meshing sound of both gears, and it is possible to improve the durability of the gear.

Further, the inclination of the rotor due to the difference in thermal expansion is suppressed, the gap between the rotors can be kept minute, and the performance can be improved.

[Brief description of drawings]

FIG. 1 is a front sectional view of a screw type supercharger according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line II-II of FIG.

FIG. 3 is a sectional view taken along the line III-III of FIG.

FIG. 4 is a front sectional view of a screw type supercharger according to a conventional example.

[Explanation of symbols]

 1 Casing 11 Female rotor 13 Male rotor 15 Female rotor shaft 17 Male rotor shaft 21a, 21b, 25a, 25b Bearing 27, 33 Bearing support member 29, 35 Bearing fitting part 31, 37 Connecting part 39, 47 Timing gear

Claims (1)

[Claims] 1. A bearing for supporting each shaft of a pair of male and female rotors is fitted in a casing made of a different material, a timing gear meshing with each rotor shaft is provided, and a suction side is provided by rotation of the rotor. A two-shaft turbocharger for pumping air sucked in from a discharge side and discharging the air from a discharge side. A pair of bearing fittings formed by a low expansion member on at least a discharge side of the casing and fitted with the bearings. A two-shaft turbocharger characterized in that a spectacle-shaped bearing support member having a portion and connecting both bearing fitting portions with a connecting portion is integrally formed by casting.