JPS61157789A - Unlubricated scroll hydraulic machine - Google Patents

Abstract

PURPOSE:To discharge the atmosphere confined during assembly of pump quickly by communicating the low pressure chamber on the backface of rolling scroll type vacuum pump through a gas vent with an enclosed chamber formed with the crankshaft and the boss section on the backface of the rolling scroll member. CONSTITUTION:The backface of a rolling scroll member 2a in scroll-type vacuum pump is formed into a low pressure chamber 5 communicated to the suction path 11. While a crankshaft 10 is fitted over the boss section 2c on the backface of the rolling scroll member and grease is filled in said section. When assembling a pump, the atmosphere encapsulated together with the grease may cause flow-out of grease through differential pressure against the low pressure chamber 5 under normal operation, but since a gas vent 14 communicatable with the low pressure chamber 5 is formed at the tip of the crankshaft, flow-out of grease can be prevented.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to an oil-free scroll fluid machine, and in particular to an oil-free scroll fluid machine having an orbiting scroll drive section suitable for application as a vacuum pump. It's about machines.

[Background of the invention]

The conventional oil-free scroll fluid machine is disclosed in Japanese Patent Application Laid-open No.
As described in Japanese Patent No. 58188, the connecting portion between the orbiting scroll and the driving element is constituted by a rolling bearing, and this bearing portion is filled with grease.

However, no consideration was given to degassing the bearing.

Therefore, when operating this scroll fluid machine as a vacuum pump, if the suction port is connected to the vacuum container that is to be vacuumed, and the orbiting scroll is coupled to the driving element to perform orbiting motion, the suction pressure will be reduced to the vacuum pressure. However, due to leakage from the end plate sliding part of the orbiting scroll, the back pressure chamber on the back surface of the orbiting scroll also becomes vacuum pressure.

If an oil-free scroll fluid machine is used in a vacuum pump,
The ultimate vacuum level can be as small as 10-”Torr, but in conventional configurations, the atmosphere sealed in by grease in the bearings gradually leaks, so even though the volume is small, gas It takes a long time for the gas to completely escape, which causes unsatisfactory results from the standpoint of vacuum pumping performance.

Another problem is that when the atmosphere leaks out of the bearing, the lubricating grease is also taken out.

This would have resulted in a significant loss in bearing life.

As another example of prior art, Japanese Patent Application Laid-open No. 160192/1987 discloses a radial hole in the end plate of an orbiting scroll that communicates with the inside of the orbiting bearing.
This is for supplying lubricating oil from the oil supply hole provided in the drive shaft to the sliding surface of the orbiting scroll end plate.The radial hole is a hole for oil supply, and its opening is located on the sliding surface. positioned.

When such a scroll fluid machine is operated as a vacuum pump, there is a problem in that a high ultimate vacuum cannot be obtained unless the gas in the motor chamber is also completely exhausted.

Furthermore, since the opening is closed by the end plate of the fixed scroll, a problem arises in that no gas venting effect can be expected.

However, the two above-mentioned publications shown here do not mention that the scroll fluid machine is operated in a vacuum, and the gas trapped in the grease in the bearing during assembly is extracted when the vacuum pump starts operating. No consideration was given to this point at all. In other words, since the above-mentioned prior art is a measure for forcibly supplying lubricating oil to sliding parts, it is almost impossible to make the oil-free scroll fluid machine function as an oil-free vacuum pump. Ta.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned problems in the prior art, and in a system that uses an oil-free scroll fluid machine as a vacuum pump, the present invention quickly removes the atmosphere trapped during assembly by starting the vacuum pump action. The object of the present invention is to provide an oil-free scroll fluid machine that is equipped with a means for evacuation and has high evacuation performance.

[Summary of the invention]

The structure of the oil-free scroll fluid machine according to the present invention is such that a fixed scroll and an orbiting scroll each having an end plate and a scroll wrap that stands upright on the end plate and is formed in a spiral shape are arranged with the scroll wrap inside. The fixed scroll is provided with an inlet and an outlet, and the orbiting scroll is coupled to a driving element via a rolling bearing to perform an orbiting motion, thereby closing the closed space formed by both scroll wraps. In an oil-free scroll fluid machine that compresses the working gas by gradually reducing the pressure, the suction port is connected to a vacuum container, and a back pressure chamber whose pressure is equal to the suction pressure of the suction port is provided at the back of the end plate of the orbiting scroll. In addition, a degassing means is provided at the joint between the orbiting scroll and the driving element.

Additionally, the idea behind developing the present invention is as follows.

JP-A-59-58, which has been disclosed as prior art
When operating the oil-free scroll fluid machine described in Publication No. 188 as a vacuum pump, in order to obtain high evacuation performance, it is necessary to properly maintain the gap between the scroll wraps and prevent leakage from the casing.

It is necessary to take measures to prevent leakage from the drive shaft. Although these techniques can be achieved by combining already known techniques, no consideration is given to reducing gas generation from the sealed part inside the pump or to simultaneously exhaust the air with the suction chamber, etc. Ta.

Regarding these two points, regarding the former viewpoint of reducing gas generation from the sealed portion, the simple sealing means conventionally used cannot prevent leakage under high vacuum. Therefore, in the present invention, as a result of taking into consideration the latter method, that is, the gas can be exhausted in the same manner as in the suction chamber, as in the embodiment described below, a hermetic seal constructed at the joint between the orbiting scroll and the driving element is used. We believe that using a gas vent hole in the space so that this space can be evacuated at the same time is a very effective means for achieving high vacuum pumping performance.

In addition, in the case of an oil-free scroll fluid machine, the joint between the orbiting scroll and the driving element is lubricated with grease to avoid lubrication, but it is necessary to prevent this grease from leaking, and as a solution to this problem, Venting the trapped gas during assembly was considered a very effective measure.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 6.

First, FIG. 1 is a longitudinal sectional view of an oil-free scroll fluid machine according to an embodiment of the present invention.

In FIG. 1, 1 is a fixed scroll, which includes an end plate 1a,
A scroll wrap 1b is provided with a scroll wrap 1b that stands upright on the end plate 1a and is formed in a spiral shape using an involute curve or the like 62 is an orbiting scroll that stands upright on the end plate 2a and is formed in a spiral shape using an involute curve or the like. The scroll wrap 2b is provided with a scroll wrap 2b. 3- is a frame, and the fixed scroll 1 is fixed to the frame 3. Reference numeral 4 denotes an orbiting scroll support member provided on the frame 3, which supports the orbiting scroll 2.

The fixed scroll 1 and the orbiting scroll 2 are engaged with each other with their scroll wraps lb and 2b facing inward to form a compression working chamber.

The fixed scroll 1 has a suction port 11 and a discharge port 13 communicating with the suction chamber 12 of the compression working chamber.

The frame 3, which fixes the fixed scroll 1 and rotatably supports the rotating frame 2, is further fixed to the casing 8, and there is a seal from the atmosphere between the three elements of the fixed frame 1, the frame 3, and the casing 8. For this purpose, a sealing means such as a ring 17 is provided.

Further, a plurality of pin cranks 6 are arranged on the same circumference of the fixed scroll 1, and are connected to the end plate 2a of the orbiting scroll 2 so as to prevent the orbiting scroll 2 from rotating.

Reference numeral 10 denotes a drive shaft for driving the orbiting scroll 2. The drive shaft 10 is connected to a drive motor (not shown) to constitute a driving element of the orbiting scroll 2, and includes a ball bearing 9 related to a rolling bearing.
It is supported by the casing 8 via a and 9b. Further, a shaft sealing means 18 for the drive shaft is provided inside the casing 8 to keep the back pressure chamber 5 on the back surface of the orbiting scroll 2 sealed.

The tip portion 10a of the drive shaft 10 (the hatched portion in FIG. It is connected within the boss 2c. The rolling bearing 15 is
Grease lubrication is used to eliminate the need for lubrication of scroll fluid machinery.

7 has an orbiting scroll 2 and a drive shaft 1 at the tip of an eccentric shaft 10a.
It is a closed space formed by combining with 0.

Reference numeral 14 denotes a gas venting hole, which is provided in the eccentric shaft 10a and has one end opened into the sealed space 7 and the other end opened into the back pressure chamber 5.

The back pressure chamber 5 is a sealed space area formed on the opposite wrap side of the orbiting scroll 2, that is, at the back of the end plate 2a. The pressure is equalized with the pressure. However, in reality, although there is an orbiting scroll support member 4 in the end plate 2a of the orbiting scroll 2), there is a small gap in the end plate 2a of the orbiting scroll 2).
Even without 9, it is possible to equalize the pressure between the back pressure chamber 5 and the suction chamber 12.

In order to operate such an oil-free scroll fluid machine as a vacuum pump, the suction port 11 is connected to a vacuum container (not shown) related to the object to be vacuumed, and the discharge port 13 is connected to a processing tank (not shown) through a duct or the like. (not shown) or open to atmosphere.

Next, the operation of the oil-free scroll fluid machine having such a configuration will be explained.

When the drive shaft 10 is rotated by a driving element such as a motor, only the orbiting motion is transmitted without the orbiting scroll 2 rotating.

Gas is sucked in from the suction port 11 connected to the vacuum container, and the fixed scroll 1. The closed space formed by both scroll wraps 1b and 2b of the orbiting scroll 2 is gradually reduced toward the center of both scroll wraps 1b and 2b, and the suction gas is compressed and discharged from the discharge port 13 to the processing tank or the atmosphere. be discharged.

At this time, the gas in the back pressure chamber 5 is also sucked in at the same time, and the suction port 1
The same vacuum pressure as in 1 is reached. And orbiting scroll 2
The gas accumulated in the sealed space 7 formed at the joint between the drive shaft 10 and the drive shaft 10 is also evacuated via the gas vent hole 14 almost simultaneously with the back pressure chamber 5 .

In this way, each part that functions as a pump chamber for the vacuum pump of a scroll fluid machine is brought to vacuum pressure almost simultaneously, so the time it takes to reach the ultimate pressure is shortened, and high vacuum evacuation performance can be maintained. I can do it.

Another effect is that even during vacuum operation, there is no differential pressure between the inside and outside of the bearing, so the grease is retained for a long period of time.As a result, the grease always provides good lubrication, extending the life of the bearing. It can be improved significantly.

It also prevents grease from flowing out.
It also has the effect of reducing grease consumption.

Next, another embodiment of the present invention will be described with reference to FIG.

Here, FIG. 2 is a longitudinal cross-sectional view of an oil-free scroll fluid machine according to another embodiment of the present invention. In the figure, the same reference numerals as in FIG. 1 are equivalent parts, so explanation thereof will be omitted. Omitted.

The embodiment shown in FIG. 2 has an orbiting scroll 2A and a drive shaft 1.
The means for coupling 0A to the eccentric shaft portion 10'a is different from the embodiment shown in FIG.

That is, the protruding shaft 2d of the orbiting scroll 2A and the hole in the eccentric shaft portion 10'a are coupled via the bearing 15A. 7A is a sealed space formed in this joint portion.

14A has one end opened in this closed space 7A.

This is a gas vent hole whose other end opens into the back pressure chamber 5A.

Reference numeral 16 denotes an Oldham ring serving as means for preventing rotation of the orbiting scroll 2A.

According to the embodiment shown in FIG. 2, the same effects as the embodiment shown in FIG. 1 can be expected, and the gas vent hole 14A is shorter than that in FIG. There is.

Next, FIG. 3 is a longitudinal cross-sectional view of an oil-free scroll fluid machine according to yet another embodiment of the present invention, and in the figure, the same reference numerals as in FIG. 1 refer to the embodiment of FIG. 1. Since they are equivalent parts, their explanation will be omitted.

The difference between the embodiment shown in FIG. 3 and the embodiment shown in FIG. 1 is as follows.
One end of the gas vent hole 14B is in the sealed space 7.

The other end is a fixed scroll 1. A closed space 20 formed by both scroll wraps lb and 2b of the orbiting scroll 2
This means that it is open to the public.

The sealed space 20 in which the gas vent hole 14B opens is desirably located as close to the suction chamber 12 as possible from the viewpoint of evacuation performance.

According to the embodiment shown in FIG. 3 having such a configuration.

In addition to the expected effects similar to those of the embodiment shown in FIG. It can completely function as an oil-free vacuum pump without leaking into the vacuum container (not shown).

Next, FIG. 4 is a longitudinal sectional view of an oil-free scroll fluid machine according to yet another embodiment of the present invention, and in the figure, the same reference numerals as those in FIG. 1 refer to the embodiment of FIG. 1. Since they are equivalent parts, their explanation will be omitted.

The difference between the embodiment shown in FIG. 4 and the embodiment shown in FIG. 1 is as follows.
One end of the gas vent hole 14c is in the closed space 7.

The other end is open to the outer peripheral portion 2c of the end plate of the orbiting scroll 2.

According to the embodiment shown in FIG. 4, the same effects as those of the embodiment shown in FIG. It can also be effectively evacuated.

What can be said about all of the embodiments shown in FIGS. 1 to 4 above is that the position where the gas vent hole communicates with the closed space 7 of the joint between the orbiting scroll 2 and the drive shaft 10, that is, the rolling bearing 15 is , it is best to locate it in the center of the part 6 because.

Grease is sealed in the bearing for lubrication, but during operation, the centrifugal force of the eccentric portion 10a of the drive shaft 10 causes the grease in the sealed space 7 to collect on the outer periphery of the rolling bearing 15. , the effective degassing position is in the center.

Next, a gas venting means according to still another embodiment of the present invention will be described with reference to FIGS. 5 and 6.

5 and 6 are enlarged cross-sectional views showing examples of the configuration of the gas vent portion of the oil-free scroll fluid machine in each of the above-mentioned embodiments of the present invention. The numbers correspond to those in the example.

First, in the embodiment shown in FIG. 5, a filter or porous material 22 is provided in the gas vent hole 14.

With this configuration, even if grease 21 is accidentally overfilled during assembly and enters the gas vent hole 14, it will be captured by the filter 22, preventing it from leaking into the vacuum pressure space. It has a preventive effect.

Next, in the embodiment shown in FIG. 6, a throttle element 23 is provided in the gas vent hole 14.In the embodiment shown in FIG. It can be made small and prevent the grease 20 from leaking.

In this case, the gas vent hole 14 may be formed into a tubular shape, and a part of the gas vent hole 14 may be crushed to narrow the flow path.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to use an oil-free scroll fluid machine as a vacuum pump,
It is possible to provide an oil-free scroll fluid machine that has a high evacuation performance and is equipped with a means for quickly evacuating the atmosphere trapped during assembly upon startup of the vacuum pump action.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of an oil-free scroll fluid machine according to an embodiment of the present invention, and FIG. 2 is a longitudinal cross-sectional view of an oil-free scroll fluid machine according to another embodiment of the present invention. 3 and 4 are longitudinal cross-sectional views of oil-free scroll fluid machines according to still other embodiments of the present invention, and FIGS. It is an enlarged sectional view showing an example of composition of a gas vent hole part of an oil-free scroll fluid machine. 1, IA...fixed scroll, la...end plate, 1b
...Scroll wrap, 2,2A...Orbiting scroll, 2a...End plate, 2b...Scroll wrap, 2
c... End plate outer periphery, 2d... Protruding shaft, 3, 3A...
·flame. 4... Orbiting scroll support member, 5, 5A... Back pressure chamber. 6...pink crank, 7,7A...closed space, 8.
...Casing, 9, 9a, 9b-ball bearing, 10. IO
A... Drive shaft, 10a+10'a... Eccentric shaft, 11
... Suction port, 12... Suction chamber, 13... Outlet port,
14, 14A. 14B, 14G... gas vent hole, 15, 15A...
Rolling bearing, 16... Oldham ring, 17... 0 ring, 18... shaft sealing means, 19... pressure equalizing hole, 20...
...Closed space, 21...Grease, 22...Filter, 23...Aperture element. brown) eyes

Claims (1)

[Claims] 1. A fixed scroll and an orbiting scroll each having an end plate and a scroll wrap formed in a spiral shape upright on the end plate are engaged with each other with the scroll wrap facing inward, and the fixed scroll is The scroll is provided with an inlet and an outlet, and the orbiting scroll is coupled to a driving element via a rolling bearing to perform orbiting motion, thereby gradually reducing the sealed space formed by both scroll wraps. In an oil-free scroll fluid machine that compresses working gas, the suction port is connected to a vacuum container, and a back pressure chamber whose pressure is equal to the suction pressure of the suction port is provided at the back of the end plate of the orbiting scroll. An oil-free scroll fluid machine characterized in that a gas venting means is provided at the joint between the scroll and the driving element. 2. In the device described in claim 1, the degassing means has one end opened in the closed space formed at the joint between the orbiting scroll and the driving element, and the other end opened in the space to be evacuated. An oil-free scroll fluid machine with a gas vent opening in the area. 3. The oil-free scroll fluid machine according to claim 2, wherein the gas vent hole opens the other end into the back pressure chamber. 4. An oil-free scroll fluid machine according to claim 2, wherein the gas vent hole opens the other end into a suction chamber or a suction passage. 5. The oil-free scroll fluid machine according to claim 2, wherein the gas vent hole opens at the other end into a closed space formed by both scroll wraps. 6. An oil-free scroll fluid machine according to any one of claims 1 to 5, wherein the gas venting means is provided with a member having a filter function in the gas venting hole. 7. An oil-free scroll fluid machine according to any one of claims 1 to 5, wherein the gas venting means includes a throttle element provided in the gas venting hole.