JPH11190286A - Scroll type vacuum pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extend the service life of a bearing used between a crankshaft and a turning scroll in a scroll type vacuum pump which uses a crankshaft. SOLUTION: A shielded or sealed radial ball bearing is employed as a bearing 8 for use between a crankshaft 5 and a turning scroll 2. A hole 14 by which a space 13 surrounded by the turning scroll 2, the crankshaft 5, and the bearing 8 is connected to a space 12 surrounded by the turning scroll 2, a fixed scroll 3 or a fixed scroll 4, and the crankshaft 5 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing between a orbiting scroll and a crankshaft and a structure around the bearing in a scroll type vacuum pump.

[0002]

2. Description of the Related Art In a conventional scroll type vacuum pump, as shown in FIG. 1, air sucked from a suction port 9 is used to convert a head plate 2c of a revolving scroll 2 and a spiral scroll wrap 2a to a head plate 3c of fixed scrolls 3 and 4. , 4c and the spiral wraps 3a, 4a, the orbiting scroll 2 revolves with respect to the fixed scroll to continuously reduce the volume of the compression space, thereby compressing the compressed space near the crankshaft 5. The suction port 9 is evacuated by exhausting air from the provided feed exhaust port 10. At this time, in order to revolve the orbiting scroll 2, an eccentric crankshaft 5 transmitting the rotational motion from the motor 11 and a crankpin 6 eccentric in the same manner as the crankshaft 5 are used.

The crankshaft 5 rotated by the motor 11 is provided with an eccentric portion 5a, and the eccentric portion 5a is rotatably engaged with the orbiting scroll 2 via a bearing 8. On the other hand, a plurality of crank pins 6 having substantially the same eccentricity as the crank shaft 5 are provided around the orbiting scroll 2, and the crank pins 6 are also rotatably engaged via bearings 7. Due to the eccentricity of the crankshaft 5 and the crankpin 6, the orbiting scroll 2 revolves with the fixed scroll 4 without rotating.

The position of the crank pin 6 is generally set outside the orbiting scroll 2 (on the suction port 9 side) in order to make the orbiting scroll 2 small, further increase the displacement, and increase the compression ratio. , Inside the vacuum pump).

Conventionally, a plurality of radial needle roller bearings 16 have been used as bearings between the orbiting scroll 2 and the crankshaft 5 as shown in FIG.

[0006]

In the scroll type vacuum pump, the air which is sucked from the suction port of the scroll type vacuum pump and compressed between the orbiting scroll and the fixed scroll and has the maximum pressure in the region near the crankshaft is originally exhausted. It is discharged from the mouth, but the seal between the fixed scroll and the orbiting scroll is not complete, and the space surrounded by the spiral wrap of the fixed scroll and the spiral wrap of the orbiting scroll, the fixed scroll, the orbiting scroll, the crankshaft, and If there is a leak in the space surrounded by the bearing between the orbiting scroll and the crankshaft, the space surrounded by the fixed scroll, the orbiting scroll and the crankshaft, and the bearing between the orbiting scroll and the crankshaft if the maximum pressure is equal to or higher than the atmospheric pressure. The pressure of the orbiting scroll and crankshaft If the maximum pressure is lower than the atmospheric pressure, the pressure of the space surrounded by the fixed scroll, the orbiting scroll, the crankshaft, and the bearing between the orbiting scroll and the crankshaft becomes higher than the atmospheric pressure. And the pressure in the space surrounded by the crankshaft and the bearing is reduced, and the grease sealed in the bearing flows out of the bearing due to the difference in these pressures.
The lubrication failure of the bearing is caused, so that the bearing has a short life (approximately 3 to 6 months) and has a disadvantage that it has to be replaced. This is because conventionally, a radial roller bearing is used as a bearing, and the grease applied to the radial roller bearing flows out of the bearing in a relatively short time due to an air flow due to a low pressure difference. This is largely due to this.

When a plurality of radial roller bearings are used as bearings, a rubber seal ring or the like may be installed between the orbiting scroll and the crankshaft to prevent foreign matter from entering. Becomes higher than 100 ° C due to the structure of the scroll vacuum pump,
Since the seal ring slides on the crankshaft in this high temperature state, the seal is easily broken by the temperature, and it is difficult to prevent the grease from flowing out due to the pressure difference.
The same applies to the case where a radial needle roller bearing and one radial ball bearing are used.

[0008]

In order to solve the above-mentioned problems, it is necessary to use a grease-enclosed type bearing which prevents grease from flowing out as much as possible. A shielded radial ball bearing in which a metallic shield plate extending from the V-groove to a position leaving a small gap is pressed to the outer ring, or a seal plate in which a V-groove is formed in the inner ring and synthetic rubber is fixed to a steel plate is attached to the outer ring. , And both side surfaces at the tip of the seal plate are arc-shaped concave surfaces, forming a narrow-wide-narrow-wide-narrow gap along the seal surface of the inner ring V-shaped groove. It is only necessary to use a radial ball bearing and prevent the grease from flowing out by sealing the shield plate or seal plate of the radial ball bearing.

In addition, since the outflow of the grease becomes remarkable when the pressure difference between the two sides becomes equal to or more than a certain level, attention should be paid to reducing the pressure difference between both ends of the bearing as much as possible. By providing a hole (air passage) that connects the space surrounded by the orbiting scroll, the crankshaft, and the bearing, and the space surrounded by the orbiting scroll, the fixed scroll, and the crankshaft, the pressure difference is reduced as much as possible to prevent grease from flowing out. Is also good.

[0010] By any of these means, a scroll type vacuum pump which can double the life of the bearing between the orbiting scroll and the crankshaft or more can be easily obtained. Also, by using these means together, a scroll type vacuum pump which can increase the life of the bearing by 3 to 4 times can be easily obtained.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is an overall external view (partially sectional view) of a scroll type vacuum pump to which the present invention is applied, and FIGS. 2 to 4 are partial sectional views near a crankshaft showing an embodiment of the present invention. .

First, referring to FIG. 1, a scroll type vacuum pump 1 includes a orbiting scroll 2, a spiral wrap 2a of the orbiting scroll 2, two fixed scrolls 3 and 4 sandwiching the orbiting scroll 2, and a spiral of the fixed scrolls 3 and 4. Wraps 3a, 4a, and tip seals 2b, 3b, 4b, crankshafts 5, crankpins 6 provided at the tips of the spiral wraps 2a of the orbiting scroll 2 and the spiral wraps 3a, 4a of the fixed scrolls 3, 4. , Shielded radial ball bearing 7 for crankpin 6, one-sided shielded radial ball bearing 8 for crankshaft 5, suction port 9, exhaust port 1
0, consisting of a motor 11.

The scroll type vacuum pump constructed as described above has a fluid pocket formed by connecting the suction port 9 to an object (chamber or the like) to be evacuated and the orbiting scroll 2 revolving with respect to the fixed scroll 3. 16
By sequentially moving the scrolls 2 and 3 from the outside to the center while compressing them, the air captured by the fluid pockets 12 is sequentially moved to the exhaust port 10.

Therefore, at the beginning of the operation, the object connected to the suction port 9 is in an atmospheric pressure state, so that the final stage 16a of the fluid pocket 16 has a considerably high pressure. Air flows into the space 13 surrounded by the shaft 5 and the bearing 8.

When a predetermined time has elapsed after the start of the operation, the object connected to the suction port 9 is in a vacuum state (for example, about 1 Pa).
Even in the final stage 12a, the air pressure is extremely low as compared with the atmospheric pressure. From the space 13 in which the pressure is increased by the air flowing at the beginning of the operation, the final stage of the fluid pocket 16 is passed over the tip seal 2b. Air flows to 16a.

Here, it is only necessary that the sealing force of the tip seal 2b be increased to completely seal the space between the final stage 16a of the fluid pocket 16 and the space 13. In this case, the tip seal 2b must be pressed against the fixed scroll 3 with a considerably strong force, and this sealing force becomes a large resistance in rotating the motor 11, which leads to waste of power consumption. Further, since the tip seal 2b is a portion that slides with respect to the fixed scroll 3, wear occurs, and it is impossible to completely seal the space between the final step 16a of the fluid pocket 16 and the space 13 for a long period of time. Have difficulty.

Therefore, first, if a grease-filled type bearing is used to prevent the grease from flowing out as much as possible, the bearing 8
Grease-filled type even if a certain degree of pressure difference occurs in both end spaces (a space 13 surrounded by the orbiting scroll 2, the crankshaft 5, and the bearing 8 and a space 12 in which the fluid leaks from the final stage 16a of the fluid pocket 16). With this bearing, leakage of grease can be reduced to some extent.

The grease-enclosed type bearing is, for example, a shield type in which a V-groove is formed in the inner ring of a bearing, and a metallic shield plate extending from the V-groove to a position leaving a small gap is pressed to the outer ring. A radial ball bearing, or a seal plate in which a V groove is formed in the inner ring and synthetic rubber is fixed to a steel plate is fixed to the outer ring. Narrow along the surface
A seal-type radial ball bearing forming a wide-narrow-wide-narrow gap is desirable.

FIG. 2 shows an example in which four single-shielded radial ball bearings 8 for the crankshaft 5 are press-fitted into the orbiting scroll 2 provided with a tip seal 2b at the tip of the spiral wrap 2a. FIG. 2 shows that the crankshaft 5 is inserted into a single-shielded radial ball bearing 8 for the crankshaft 5.
FIG. 4 is a partial cross-sectional view showing a state in which both sides are sandwiched between two fixed scrolls 3 and 4 in which tip seals 3b and 4b are provided at the tips of spiral wraps 3a and 4a, and two single-shielded radial ball bearings 8; The grease can be prevented from leaking out even in the single shield type by incorporating the shield so that the shield side is on the outside, and the life of the bearing can be extended.
A similar effect can be obtained with a single-seal radial ball bearing.
Further, when the double shield type and double seal type are used, the number of seals is reduced, and the influence of the pressure difference is weakened, so that the life can be further extended. That is, even if the air flow due to the pressure difference as described above occurs in the space at both ends of the bearing 8, the grease in the bearing can be prevented from leaking as much as possible, and the life of the bearing can be extended (so that the scroll type The life of the vacuum pump can be prolonged.

The use of a grease-enclosed bearing for the bearing 8 provides a certain effect (extended life).
However, since the grease sealing input of the grease-enclosed type bearing is not perfect, when the pressure difference between both end spaces of the bearing 8 becomes considerably large, the grease gradually leaks. (However, the leakage is considerably lower than that of the conventional radial roller bearing.) In order to suppress such leakage, the applicant has made the orbiting scroll 2 so as to minimize the pressure difference between both end spaces of the bearing 8. A space 13 surrounded by the rotary shaft 2, the crankshaft 5, and the bearing 8, and holes 14, 15 (air passages) connecting the orbiting scroll 2, the fixed scroll 3, and the space 12 surrounded by the crankshaft 5, thereby minimizing a pressure difference. Devised. Naturally, the flow path resistance of the holes 14 and 15 is considerably lower than the flow path resistance of the bearing 8, so that most of the air does not pass through the bearing 8 but passes through the holes 14 and 15 in the space at both ends of the bearing 8. Pressure difference is reduced.

FIG. 3 shows four single-shielded radial ball bearings 8 for the crankshaft 5 pressed into the orbiting scroll 2 provided with a tip seal 2b at the tip of the spiral wrap 2a. FIG. 4 is a partial cross-sectional view showing a state in which a crankshaft 5 is inserted into a bearing 8, and both sides of the crankshaft 5 are sandwiched between two fixed scrolls 3, 4 having tip seals 3 b, 4 b provided at the tips of spiral wraps 3 a, 4 a. Space 12 surrounded by scroll 3 or 4, orbiting scroll 2, crankshaft 5, and single-shielded radial ball bearing 8 for crankshaft 5, single-shielded radial ball bearing 8 for orbiting scroll 2, crankshaft 5, and crankshaft 5. A space 13 surrounded by a hole is formed by a through hole 14 provided in an eccentric portion of the crankshaft 5. It wants.

FIG. 4 also shows four single-shielded radial ball bearings 84 for the crankshaft 5 pressed into the orbiting scroll 2 in which a tip seal 2b is provided at the tip of the spiral wrap 2a. The crankshaft 5 is inserted into the ball bearing 8, and the tip ends of the spiral wraps 3 a, 4 a are attached to the tip ends of the spiral seals 3 b, 4 b on both sides thereof.
Is a partial cross-sectional view showing a state where the fixed scroll is sandwiched between two fixed scrolls 3 and 4 provided with the fixed scroll 3 or 4, the orbiting scroll 2, the crankshaft 5, and the crankshaft 5.
Space 1 surrounded by a shielded radial ball bearing 8
2, the orbiting scroll 2, the single-shielded radial ball bearing 8 for the crankshaft 5, and a space 13 surrounded by the crankshaft 5 are provided with holes 15 provided in the orbiting scroll 2.
a, 15b, and 15c.

3 and 4, the pressure and swirl of the space 12 surrounded by the fixed scroll 3 or 4, the orbiting scroll 2, the crankshaft 5, and the single shielded radial ball bearing 8 for the crankshaft 5. The pressure in the space 12 surrounded by the scroll 2, the single-shielded radial ball bearing 8 for the crankshaft 5, and the crankshaft 5 is generated by the hole 14 provided in the crankshaft 5 or the holes 15 a, 15 b, 15 c provided in the orbiting scroll. Although the pressure difference on both sides of the single-shielded radial ball bearing 8 for the crankshaft 5 is equalized and the grease of the radial ball bearing 8 does not flow out, the life of the radial ball bearing 8 can be extended, but as shown in FIG. Drilling holes in the crankshaft 5 will drill holes in the orbiting scroll 2 shown in FIG. Practical in terms of drilling ease of shallow and can the same direction processing, etc. The depth of the machined hole than in law preferred.

[0025]

As described above, according to the present invention, the space surrounded by the orbiting scroll, the crankshaft, and the bearing,
The space enclosed by the bearing between the orbiting scroll and the fixed scroll and the crankshaft, and between the orbiting scroll and the crankshaft can be made tighter, or the space surrounded by the orbiting scroll and the crankshaft and the bearing, and the orbiting scroll and the fixed Because the space surrounded by the scroll and crankshaft can be made almost the same pressure,
The bearing between the orbiting scroll and the crankshaft can have a long life.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional overall view of a scroll type vacuum pump according to an embodiment of the present invention.

FIG. 2 is a partial sectional view showing one embodiment of the present invention.

FIG. 3 is a partial sectional view showing another embodiment of the present invention.

FIG. 4 is a partial sectional view showing still another embodiment of the present invention.

FIG. 5 is a partial cross-sectional view showing a conventional example.

[Explanation of symbols]

1 is a scroll type vacuum pump, 2 is a revolving scroll, 2
a is the spiral wrap of the orbiting scroll, 2b is the tip seal of the orbiting scroll, 2c is the end plate of the orbiting scroll,
3 and 4 are fixed scrolls, 3a and 4a are spiral wraps of fixed scrolls, 3b and 4b are tip seals of fixed scrolls, 3c and 4c are end plates of fixed scrolls, 5 is a crankshaft, 6 is a crankpin, 7a and 7b. , 7c are bearings for crankpins, 8 are bearings for crankshafts, 9
Is an intake port, 10 is an exhaust port, 11 is a motor, 12 is a space surrounded by a fixed scroll, a revolving scroll, a crankshaft and a single shield type radial ball bearing for a crankshaft, 13 is a revolving scroll and a single shield type for a crankshaft. A space surrounded by the radial ball bearing and the crankshaft, 14 is a hole provided in the eccentric portion of the crankshaft, 15a, 15b, 15c are holes provided in the orbiting scroll, and 16 is a radial needle roller bearing.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Mitsuo Ogura, Inventor, Hitachi Koki Co., Ltd., 1060 Takeda, Hitachinaka-shi, Ibaraki Prefecture

Claims (8)

[Claims] A first spiral scroll wrap provided to stand up from the end plate of the orbiting scroll; a second spiral scroll wrap provided to stand up from the end plate of the fixed scroll; The orbiting scroll is connected to an electric motor by an eccentric crankshaft, and the crankshaft rotates when the electric motor rotates, so that the crankshaft rotates. In a scroll-type vacuum pump in which rotational motion is transmitted to the orbiting scroll by a bearing installed between a crankshaft and the orbiting scroll and converted into orbital motion by a crankpin, two or more bearings are used as bearings between the orbiting scroll and the crankshaft. Use shielded or sealed radial ball bearings. Scroll type vacuum pump. 2. A hole is provided to connect a space surrounded by the orbiting scroll, the crankshaft, and the radial ball bearing, and a space surrounded by the orbiting scroll, the fixed scroll, the crankshaft, and the space surrounded by the radial ball bearing between the orbiting scroll and the crankshaft. The scroll type vacuum pump according to claim 1, wherein: 3. A hole connecting a space surrounded by the orbiting scroll, the crankshaft and the radial ball bearing, and a hole connecting a space surrounded by the orbiting scroll, the fixed scroll and the crankshaft, and the space surrounded by the radial ball bearing between the orbiting scroll and the crankshaft. 3. The scroll type vacuum pump according to claim 2, wherein the scroll type vacuum pump is provided. 4. An orbiting scroll having a hole connecting a space surrounded by an orbiting scroll, a crankshaft, and a radial ball bearing, and a space connected by a space surrounded by a radial ball bearing between the orbiting scroll, a fixed scroll, a crankshaft, and the orbiting scroll and a crankshaft. 3. The scroll type vacuum pump according to claim 2, wherein the scroll type vacuum pump is provided. 5. The apparatus according to claim 1, further comprising a first spiral scroll wrap so as to stand up from the end plate of the orbiting scroll, a second spiral scroll wrap so as to stand up from the end plate of the fixed scroll, and said first spiral. The orbiting scroll is connected to an electric motor by an eccentric crankshaft, and the crankshaft rotates when the electric motor rotates, so that the crankshaft rotates. In a scroll type vacuum pump in which rotational motion is transmitted to the orbiting scroll by a bearing installed between a crankshaft and the orbiting scroll and converted into orbital motion by a crankpin, a space surrounded by the orbiting scroll, the crankshaft, and the bearing; Orbiting scroll, fixed scroll and crankshaft And a hole connecting the space surrounded by the bearing between the orbiting scroll and the crankshaft. 6. A crankshaft is provided with a hole connecting a space surrounded by the orbiting scroll, the crankshaft, and the bearing, a space surrounded by the bearing between the orbiting scroll, the fixed scroll, the crankshaft, and the bearing between the orbiting scroll and the crankshaft. The scroll type vacuum pump according to claim 5, wherein: 7. The orbiting scroll has a hole connecting the space surrounded by the orbiting scroll, the crankshaft and the bearing, and the space surrounded by the bearing between the orbiting scroll, the fixed scroll and the crankshaft, and the bearing between the orbiting scroll and the crankshaft. The scroll type vacuum pump according to claim 5, wherein: 8. The scroll type vacuum pump according to claim 6, wherein two or more shielded or sealed radial ball bearings are used as bearings between the orbiting scroll and the crankshaft.