JPH05332284A - Vacuum pump - Google Patents

Abstract

PURPOSE:To achieve compactness and low cost of a vacuum pump, and also increase reliability of it. CONSTITUTION:In a vacuum pump which is provided with a cascade in which multiple rotary disks 1A and static disks 2A are arranged alternately and drive mechanisms 4 and 10, and in which the rotary disks 1A are connected to a rotating shaft 3 with the drive mechanism 4, at least one stage of the rotary disks 1A is formed separately from the other rotary disks 1A, and the static disks 2A of integral construction are arranged on the drive mechanism side near the separately formed rotary disk 1A. Because the static disks 2A are of integral construction, counterflow of gas from the drive mechanism side to the side opposite to the mechanism is eliminated. Therefore, a feed capacity of the vacuum pump [exhaust velocity S: volumetric flow per unit of time (1/s)] is increased to obtain large exhaust velocity, and the necessity to increase the diameter and number of stages of the disks of the vacuum pump is eliminated to achieve compactness and low cost of the vacuum pump.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vacuum pump, for example, a jig burn type vacuum pump.

[0002]

2. Description of the Related Art A conventional jig burn type vacuum pump is shown in FIG.
Explaining with reference to FIG. 9, 1 in FIG. 8 is a multi-stage rotating disk,
The respective rotary disks 1 are integrally formed. 3 is a rotating shaft, and the rotating shaft 3 and each of the rotating discs 1 are integrally fastened together by a nut 5, and a bearing 6 connects the rotating shaft 3 and each of the rotating discs 1 in a casing 8 and a housing 9. It is rotatably supported by.

Reference numeral 2 is a multistage stationary disk, and 7 is each stationary disk 2.
By fixing the casing 8 to the housing 9 with a spacer interposed between the stationary disk 2 and the spacer 7, the stationary disk 2 and the spacer 7 are fixed to the inner peripheral surface of the casing 8. Are opposed to the rotary discs 1 with a narrow gap. Reference numeral 4 denotes a motor rotor mounted on the rotary shaft 3, and 10 denotes a motor stator mounted in the housing 9 so as to face the motor rotor 4. The motor rotor 4 and the motor stator 10 constitute a drive mechanism for the rotary shaft 3. Has been done.

At least one of the rotating disk 1 and the stationary disk 2 facing each other as described above is provided with the grooves 2a and the ridges 2b alternately as shown in FIG. A ball bearing having steel balls is used as the bearing 6, and a lubricating oil 13 is used as a lubricating material. The lubricating oil 13 is stored in a lubricating oil tank 16 provided in the lower part of the housing 9, and the lubricating oil 13 is pump 14 → lubricating oil pipe 15 →
While supplying the lubricating oil to the ball bearing 6 through the lubricating oil passage provided in the housing 9, the lubricating oil discharged from the ball bearing 6 is dropped in the direction of the arrow and returned to the lubricating oil tank 16 to cool the ball bearing 6. I have to.

There is a narrow gap between each of the rotating discs 1 and the stationary disc 2, and when the rotating shaft 3 and each of the rotating discs 1 are rotated, the rotating disc 1 and the stationary disc 2 are separated from each other. Due to the hydrodynamic action, the gas flows from the side opposite to the driving mechanism to the side of the driving mechanism as shown by the arrow in FIG. 10, and as a result, the gas is transferred from the intake port 11 to the exhaust port 12 in FIG. A container (not shown) is provided on the intake port 11 side, the exhaust port 12 is open to the atmosphere, and when the pump is operated, the inside of the container becomes a vacuum.
The pressure reaches 10 ⁻⁵ to 10 ⁻⁶ Torr. Here, the multi-stage rotary disc 1 is integrally formed as a whole. On the other hand, a stationary disc 2 arranged between the rotating discs 1
As will be described later, is divided into two left and right with a central portion as a boundary from the viewpoint of assembly, as shown in FIG.

[0006] A multi-stage rotating disc 1 formed integrally with the above,
At the time of assembling each stationary disk 2 having the above-mentioned divided structure and each spacer 7, since the inner diameter d of the stationary disk 2 is smaller than the outer diameter D of the rotating disk 1 as shown in FIG. The stationary disk 2 is inserted from the left and right between the upper and lower rotating disks 1, while the spacer 7 is interposed between the stationary disks 2 to assemble these parts.

[0007]

The conventional jig-burn type vacuum pump shown in FIGS. 8 and 9 has the following problems. That is, (1) a rotating disc 1 which is multi-staged and integrated with each other, and each stationary disc 2 which can be divided into left and right sides with a central portion as a boundary as shown in FIG.
In between, the gas flows from the counter drive mechanism side to the drive mechanism side as shown in FIG. If the pressure on the drive mechanism side at this time is PL and the pressure on the opposite drive mechanism side is PU, PL> PU
Therefore, a part of the gas flows backward from the drive mechanism side to the counter drive mechanism side through the dividing surface of the stationary disk 2 as indicated by the broken line arrow in FIG. 10, and the transfer capacity of the vacuum pump (exhaust speed S: unit time Per volume flow rate [l / s]) decreases.

In order to compensate for this decrease in exhaust speed, it is necessary to increase the exhaust speed in the conventional vacuum pump, and therefore, measures such as increasing the disc diameter and increasing the number of stages are taken. A jig-burn type vacuum pump becomes large and costly for its pumping speed. (2) Further, the conventional jig burn type vacuum pump shown in FIGS. 8 and 9 requires a lubricating oil system in order to cool the ball bearing 6 having steel balls. This lubricating oil system includes a lubricating oil tank 16, a pump 14, a lubricating oil pipe 15, and the like. In addition, this lubricating oil system requires a sequence control circuit or the like for stopping the operation of the vacuum pump when these lubricating oil devices fail. Therefore, one of the features of the jig burn type vacuum pump, that is, miniaturization and cost reduction is hindered from the above point, and the size and cost are increased.

Further, since the lubricating oil 13 is used, regular inspection and maintenance are troublesome, and the mounting posture is restricted due to the arrangement of the lubricating oil tank 16 and the like, which considerably restricts the application. was there. The present invention is proposed in view of the above problems, and an object thereof is to provide a vacuum pump that can achieve downsizing, cost reduction, reliability improvement, and further expansion of applications. There is a point to do.

[0010]

In order to achieve the above object, the present invention provides a rotating shaft having a drive mechanism, a bearing for rotatably supporting the rotating shaft, a plurality of rotating disks and a stationary member. In a vacuum pump having blade rows in which discs and discs are alternately arranged, the rotary discs being fastened to the rotary shaft, at least one stage of each of the rotary discs is separated from other rotary discs. In addition to the above, the stationary disk of the integral structure is arranged on the side of the drive mechanism near the separately formed rotating disk.

The present invention also provides the above vacuum pump,
Each rotating disk and each stationary disk are opposed and arranged with a narrow gap between them, and either one or both of the facing surfaces of the pair of rotating disk and stationary disk combination. A spiral groove is provided on the. Further, according to the present invention, in the vacuum pump, a ball bearing having a ceramic ball is used as a bearing.

[0012]

According to the vacuum pump of the present invention, at least one stage of each rotary disc is formed separately from the other rotary discs as described above, and on the drive mechanism side near the separately formed rotary disc. Since the stationary disk having an integral structure is arranged and the stationary disk is an integral structure, there is no backflow of gas from the drive mechanism side to the counter drive mechanism side. Therefore, the transfer capacity of the vacuum pump (exhaust rate S: volume flow rate per unit time [l / s]) is improved, a large exhaust rate is obtained, and it is necessary to increase the disk diameter of the vacuum pump and increase the number of stages. Is eliminated, the vacuum pump is downsized,
Cost reduction is achieved. In addition, although the back flow rate of the stationary disc of the split structure had individual differences among products, the static disc is an integrated structure, and since the above back flow is eliminated, there is no variation in the exhaust speed between products, and the vacuum pump Improves reliability.

As described above, the vacuum pump of the present invention uses a ball bearing having a ceramic ball as a bearing, and has a specific gravity smaller than that of a conventional steel ball (steel: about 7.8, ceramics. : About 3.2), the centrifugal force generated during rotation becomes small. For this reason, the heat generation of the ball bearing having the ceramic balls is also small, cooling with grease is sufficient, and cooling with lubricating oil is no longer necessary. As a result, a large-scale lubricating oil system is not required, and the vacuum pump Miniaturization and cost reduction are achieved.

Further, the need for periodical inspection and maintenance of the lubricating oil system is eliminated, and the mounting posture is not restricted by the arrangement of the lubricating oil tank or the like, and the application is expanded.

[0015]

【Example】

(First Embodiment) Next, a vacuum pump according to the present invention will be described with reference to a first embodiment shown in FIGS. 1 and 2. 1A of FIG. Is a rotary shaft, and the rotary discs 1A and the rotary shaft 3 are integrally fastened by a nut 5, and the rotary shaft 3 and the rotary discs 1 are rotated in a casing 8 and a housing 9 by a bearing 6. Supported as possible.

2A in FIGS. 1 and 2 are multistage stationary discs, and these stationary discs 2A are not divided as shown in FIG. 2 and have an integral structure. Reference numeral 7 is a spacer interposed between the stationary disks 2A, and the casing 8 is a housing 9
The stationary discs 2A and the spacers 7 are fixed to the inner peripheral surface of the casing 8 by fixing the stationary discs 2A to the rotating discs 1A with a slight gap therebetween. Are facing each other.

The spiral grooves 2a and the ridges 2b are alternately provided on either or both facing surfaces of the pair of combinations of the rotating disks 1A and the stationary disks 2A. Reference numeral 4 in FIG. 1 denotes a motor rotor mounted on the rotary shaft 3,
Reference numeral 10 denotes a motor stator mounted in the housing 9 so as to face the motor rotor 4, and the motor rotor 4
The motor stator 10 constitutes a drive mechanism for the rotating shaft 3.

As described above, there is a narrow gap between each rotating disc 1A and each stationary disc 2A. Moreover, each rotating disk 1
Of the pair of combinations of A and each stationary disk 2A, spiral grooves 2a and peaks 2b are alternately provided on either or both facing surfaces, and the rotary shaft 3 and each rotary disk 1A.
When is rotated, gas flows from the side opposite to the drive mechanism to the drive mechanism as shown by the arrow in FIG. 3 due to the hydrodynamic action of the rotating disc 1A and the stationary disc 2A, and as a result, the intake port of FIG. 1
The gas is transferred from 1 to the exhaust port 12.

A container (not shown) is provided on the intake port 11 side, the exhaust port 12 is open to the atmosphere, and when the pump is operated, the inside of the container becomes a vacuum. The pressure is 10
^{Reach -5} to 10 ^-6 Torr. If the pressure on the drive mechanism side at this time is PL and the pressure on the opposite drive mechanism side is PU, PL
> PU, but since the stationary disk 2A has an integral structure, no backflow of gas occurs (see FIG. 3). Therefore, compared with the case where the stationary disk 2A is divided, a large exhaust speed can be obtained despite the same groove condition.

Next, the procedure for assembling each rotating disc 1A and each stationary disc 2A will be described with reference to FIG. The assembly is performed by alternately stacking the rotating disks 1A and the stationary disks 2A from the drive mechanism side to the counter drive mechanism side. That is, FIG.
(A) shows that the hole provided in the central portion of the rotary disc 1A on the drive mechanism side is engaged with the rotary shaft 3 to assemble the rotary disc 1A to the rotary shaft 3, while the spacer 7 on the drive mechanism side is attached. The housing 9
It shows a state of being placed on the upper surface of.

From this state, the stationary disk 2A is placed on the spacer 7 as shown in FIG. 4 (b). At this time, since the rotary disc 1A on the side opposite to the drive mechanism is not yet assembled to the rotary shaft 3, the stationary disc 2A having the integral structure has an inner diameter d.
Is smaller than the outer diameter D of the rotating disc 1A,
The stationary disc 2A can be easily placed on the spacer 7.

Next, as shown in FIG. 4 (c), a hole provided at the center of the next rotating disk 1A is engaged with the rotating shaft 3 to assemble the rotating disk 1A to the rotating shaft 3. Next, as shown in FIG. 4D, the next spacer 7 is placed on the spacer 7. As described above, one cycle of assembling is completed, and thereafter, the rotating disk 1A, the stationary disk 2A, and the spacer 7 are sequentially stacked in the same manner.

Even if all of the rotating discs 1A are not individually formed, if at least one rotating disc 1A is formed individually, the stationary disc 2 on the side of the driving mechanism near the rotating disc 1A is formed.
A can be made into an integral structure, and the object of the present invention can be achieved. (Second Embodiment) Next, a vacuum pump of the present invention will be described with reference to a second embodiment shown in FIGS. 5 and 6. The same parts as those in the first embodiment are designated by the same reference numerals. 1C is the intake port 1
The first and second stage rotating discs counting from 1
The stage and the second stage rotating discs 1C are integrally formed. 1
A is a rotating disc of the third stage to the fifth stage, and these rotating discs 1
Each of A is individually formed.

On the other hand, the stationary disc 2 of the second stage has a divided structure, but the other stationary discs 2A have an integral structure, and no backflow of gas occurs in this portion.
In each of the above-mentioned embodiments, an example of a grooved rotary disk is shown, but in addition to this, a rotary disk used in general rotary machines such as centrifugal type, spiral type, axial flow type, etc. may be used instead. It doesn't matter.

(Third Embodiment) Next, a vacuum pump of the present invention will be described with reference to a third embodiment shown in FIG. 6 is a ball bearing that rotatably supports the rotating shaft 3, and the ball bearing 6 includes an outer race 6A, an inner race 6B, and a plurality of ceramic balls 6C interposed between the outer race 6A and the inner race 6B. It is composed of and. Then, the inner race 6B is fitted and fixed to the rotary shaft 3 by shrink fitting, etc., and the outer race 6A is attached to the housing 9.

During the operation of the vacuum pump, the rotational force of the rotary shaft 3 is passed through the inner race 6B and the ceramic balls 6C.
Be transmitted to. Since the centrifugal force of the ceramic balls 6C at this time is proportional to the weight, if a ceramic having a small specific gravity (for example, Si ₃ N ₄ : 3.2) is used, the centrifugal force of the ball bearing 6 using the steel balls is increased. Smaller than if. Further, the frictional force proportional to the centrifugal force is also small in the case of the ceramic ball 6C, so that the heat generation accompanying it is small. When the heat generation is small, it is sufficient to cool with grease lubrication.

As the ball bearings, there are a so-called deep groove type shown in FIG. 7, an angular type, a type with a retainer, and the like. What type of action does the ceramic ball 6C reduce in centrifugal force? But it will be achieved.

[0028]

According to the present invention, as described above, the vacuum pump has a blade row in which a plurality of rotating disks and stationary disks are alternately arranged, and each rotating disk is fastened to a rotating shaft having a drive mechanism. In the above, at least one stage of each of the rotating discs is formed separately with respect to the other rotating discs, and the integrally formed stationary disc is arranged near the separately formed rotating discs on the drive mechanism side. Since the stationary disk is an integral structure, it is possible to eliminate the backflow of gas from the drive mechanism side to the counter drive mechanism side, and the following effects can be achieved. That is, (1) the transfer capacity of the vacuum pump (exhaust rate S: volume flow rate per unit time [l / s]) can be improved, a large exhaust rate can be obtained, the disk diameter of the vacuum pump increases, and the number of stages increases. It is possible to eliminate the need for the above, and it is possible to reduce the size and cost of the vacuum pump. (2) There were individual differences in the reverse flow rate of the stationary disc with the split structure, but since the stationary disc is an integrated structure and backflow can be eliminated, it is possible to eliminate variations in the exhaust speed between products. It is possible to improve the reliability of the vacuum pump.

The vacuum pump of the present invention uses the ball bearing having the ceramic balls as the bearing as described above, and the following effects can be achieved. (3) Compared with the conventional steel balls, the specific gravity is small (steel: about 7.8, ceramics: about 3.2) and the centrifugal force generated during rotation is small. For this reason, the heat generation of the ball bearing having the ceramic balls is also small, cooling with grease is sufficient, and cooling with lubricating oil is not necessary. As a result, a large-scale lubricating oil system can be eliminated, and the vacuum pump Miniaturization and cost reduction can be achieved. (4) The need for periodical inspection and maintenance of the lubricating oil system is eliminated, and the mounting posture is not restricted by the arrangement of the lubricating oil tank or the like, and the application can be expanded.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view showing a first embodiment of a vacuum pump of the present invention.

FIG. 2 is a plan view showing a stationary disc of the vacuum pump.

FIG. 3 is an operation explanatory view of the vacuum pump.

4 (a) to (d) are explanatory views showing an assembling procedure of the vacuum pump.

FIG. 5 is a vertical sectional side view showing a second embodiment of the vacuum pump.

FIG. 6 is a plan view showing a stationary disk of the vacuum pump.

FIG. 7 is a perspective view showing a third embodiment of the vacuum pump.

FIG. 8 is a vertical cross-sectional side view showing a conventional vacuum pump.

FIG. 9 is a plan view showing a stationary disk of the vacuum pump.

FIG. 10 is an operation explanatory view of the vacuum pump.

FIG. 11 is an explanatory view showing an assembling procedure of the vacuum pump.

[Explanation of symbols]

 1A rotating disc 1C 〃 2 stationary disc 2A 〃 2a groove 2b mountain 3 rotating shaft 4 motor rotor (rotating side drive mechanism) 5 nut 6 ball bearing 6A outer race 6B inner race 6C ceramic ball 7 spacer 8 casing 9 housing 10 motor stator ( Stationary drive mechanism) 11 Inlet port 12 Exhaust port 13 Lubricating oil 14 Pump 15 Lubricating oil pipe 16 Lubricating oil tank

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hitoshi Yamada 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries Hiroshima Works

Claims (3)

[Claims] 1. A rotary shaft having a drive mechanism, a bearing rotatably supporting the rotary shaft, and a blade row in which a plurality of rotary disks and stationary disks are alternately arranged. In a vacuum pump in which a rotating disc is fastened to the rotating shaft, at least one stage of each rotating disc is formed separately from other rotating discs, and a drive mechanism near the separately formed rotating discs. A vacuum pump characterized in that a stationary disk with an integral structure is placed on the side. 2. The rotating disk and the stationary disk are opposed to each other with a narrow gap therebetween and are arranged, and any one of a pair of combinations of the rotating disk and the stationary disk is provided. The vacuum pump according to claim 1, wherein a spiral groove is provided on one or both opposing surfaces. 3. The vacuum pump according to claim 1, wherein a ball bearing having ceramic balls is used as the bearing.