JP7212926B2 - scroll vacuum pump - Google Patents

Description

The present invention relates to a scroll-type vacuum pump having a drive scroll member and a driven scroll member, and sucking gas from a suction port by changing a space defined by the drive scroll member and the driven scroll member.

Patent Document 1 (Japanese Patent Publication No. 2002-527670) discloses a scroll type vacuum pump. This scroll type vacuum pump has an expander and a compressor which are arranged in the same housing as two stages in series and driven by the same shaft, whereby the re-expansion and compression processes are to allow for the overheating normally associated with This patent document 1 discloses that in a scroll type vacuum pump, the first stage is a scroll type expander and the second stage is a scroll type compressor.

Japanese translation of PCT publication No. 2002-527670

When the expander is used as a vacuum pump, as disclosed in U.S. Pat. No. 5,400,402, the air pressure in the discharge pocket is significantly lower than the ambient air pressure, causing the ambient air to re-expand towards the discharge pocket. This re-expansion of ambient air consumes energy and causes overheating. Also, if the compressor is used as a vacuum pump and the inlet air to the compressor is at atmospheric pressure during start-up or due to leaks to the atmosphere, there is usually no lubrication or internal cooling, so the re-expansion/compression process will not be possible. The accompanying heat damages the compressor, and the re-expansion/compression heat causes an excessive heat increase in the scroll element, resulting in galling between the tip and base of the scroll element. Further, the scroll-type vacuum pump disclosed in Patent Document 1 has a two-stage structure consisting of an expander and a compressor, which causes a problem of increasing the size of the apparatus itself.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a scroll type vacuum pump that employs an expansion type that does not generate heat of compression and has a structure that enables efficient suction and discharge.

The present invention comprises a housing defining therein a working space communicating with a discharge port, a pair of rotating shafts rotatably held in the housing, and fixed to the respective rotating shafts arranged in the working space. a driven scroll member arranged between the pair of driven scroll members; and a pair of driven scroll receivers rotatably holding the driven scroll member in the housing. In a scroll-type vacuum pump in which a movement space is defined by driven scroll wraps erected on both sides of a member and drive scroll wraps of drive scroll members meshing with the driven scroll wraps, the movement space is defined by the rotation The central side of the shaft communicates with a suction port formed on one of the rotating shafts, and the outermost peripheral end communicates with the working space, and the volume expands from the central side toward the outer peripheral direction to provide a predetermined space for the outermost peripheral wrap. To reduce its volume in range.

As a result, in the scroll type vacuum pump described above, when the rotating shaft is rotated by an external power source such as an electric motor, the driving scroll member and the driven scroll member rotate at high speed, and at the same time, the driven scroll member rotates relative to the driving scroll member. Since the fluid is swirling, the fluid sucked from the suction port formed on the rotating shaft is sucked into the moving space whose volume expands from the center side toward the outer circumference and is decompressed, and moves in the outer circumference direction. On the other hand, the volume of the outermost wrap is reduced and compressed, and can be discharged from the discharge port through the working space.

In addition, it is preferable that each of the drive scroll wraps has a large width in the range where the outermost wrap undergoes the compression stroke. Thus, the driving scroll wrap and the driven scroll wrap according to the present invention are the outermost circumferential wraps of the driving scroll wrap and the driven scroll wrap (specifically, the range of 270° from the outermost circumferential end or 3π/2 [rad]). By increasing the width of the scroll wrap in the range of ), it is possible to withstand the centrifugal force applied to the outermost wrap and to withstand the pressure when the fluid is compressed.

It is preferable that the driven scroll member located at the outermost end of the movement space is formed with a discharge hole, and a check valve is provided in the discharge hole. As a result, it is possible to prevent backflow when the fluid is discharged, so that the sucked fluid can be reliably discharged. The check valve is desirably a reed valve formed to cover the discharge hole. Furthermore, the reed valve is desirably installed on the center line of the driven scroll member in order to reduce the influence of centrifugal force.

Each drive scroll member is desirably connected at its outer peripheral portion as a pressure counteracting mechanism. Specifically, it is desirable that the outer peripheral portion of the drive scroll wrap of one of the drive scroll members is fitted into a groove formed in the portion corresponding to the other drive scroll member. As a result, since the vacuum pressure can be supported by the strength of the drive scroll wrap, the strength of the drive scroll member can be increased. In addition, this structure prevents the vacuum pressure from acting on the bearings, thereby extending the life of the bearings.

Moreover, it is desirable to provide a shaft seal or a magnetic fluid seal at the end of the rotating shaft where the suction port is formed, depending on the degree of vacuum to be achieved. In the structure described above, only the end portion of the rotating shaft where the suction port is formed needs to be sealed with, for example, a magnetic fluid, so the structure is simple and the cost can be reduced.

According to the present invention, since the gas is sucked from the suction port while being expanded, heat of compression is not generated, so there is an effect that a cooling mechanism is not required. Moreover, since it is sufficient to seal only the peripheral edge of the rotary shaft having the suction port, the structure is simple and the cost can be reduced. Furthermore, since there is only one sealing portion, there is an effect that a high vacuum can be obtained. Furthermore, even if the fluid is a condensable gas such as water vapor, it can be separated by centrifugal force, so there is an effect that a mechanism such as a gas ballast is not required. Furthermore, due to the pressure offset mechanism, there is also the effect that the vacuum pressure does not act on the bearings. Furthermore, since the vacuum portion is only the moving space on the central side, there is an effect that the ultimate vacuum can be obtained quickly.

BRIEF DESCRIPTION OF THE DRAWINGS It is cross-sectional explanatory drawing which showed the structure of the scroll-type vacuum pump based on the Example of this invention. FIG. 4 is an explanatory diagram showing states of expansion and compression according to the embodiment of the present invention; FIG. 2 is an explanatory diagram showing a check valve structure according to an embodiment of the present invention; It is an explanatory view showing a pressure offset mechanism according to an embodiment of the present invention.

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

As shown in FIG. 1, a scroll type vacuum pump 1 according to an embodiment of the present invention is provided with a discharge port 2 and comprises a housing 5 defining therein a working space 3 communicating with the discharge port 2. . A vacuum pump mechanism 4 is arranged in the working space 3 . In addition, the housing 5 includes a cylindrical side surface portion 5a provided with the discharge port 2, a housing lid portion 5b that rotatably holds the first rotating shaft 7 having the suction port 6 formed thereon through a bearing 9, A housing bottom portion 5 c that rotatably supports a second rotating shaft 8 connected to an external power source such as an electric motor 60 via a bearing 10 . An end portion of the first rotary shaft 7 is provided with a shaft seal or a magnetic fluid seal 40 depending on the degree of vacuum achieved. Also, the second rotating shaft 8 and the electric motor 60 are connected via a coupling 50 .

A first end plate 11 is formed integrally with the first rotating shaft 7, and a side surface of the first end plate 11 opposite to the first rotating shaft 7 is radially outward from the center direction. A spirally extending first driven scroll wrap 12 is provided. A first driving scroll member 13 is composed of the first rotating shaft 7 , the first end plate 11 and the first driving scroll wrap 12 . A second end plate 14 is formed integrally with the second rotating shaft 8, and on the side opposite to the second rotating shaft 8 of the second end plate 14, radially outward from the center direction. A second driven scroll wrap 15 is provided which spirals out toward. A second drive scroll member 16 is composed of the second rotating shaft 8 , the second end plate 14 and the second drive scroll wrap 15 .

A driven scroll member 17 is arranged between the first drive scroll member 13 and the second drive scroll member 16 . The driven scroll member 17 is formed with an end plate 18 and first and second driven scroll wraps 19 and 20 spirally expanding radially outward from the center direction on both sides of the end plate 18 . First and second driven scroll receivers 24 and 25 are connected to the outer peripheral portion of the driven scroll member 17, and the first driven scroll receiver 24 rotates to the housing lid portion 5b via a bearing 26. The second driven scroll receiver 25 is rotatably supported by the housing bottom portion 5c via a bearing 27. As shown in FIG. An Oldham ring 28 is provided between the driven scroll receiver 25 and the second end plate 14 of the second drive scroll member 16 to prevent the driven scroll member 17 from rotating.

With this configuration, the first movement space 21 is defined by the first drive scroll wrap 12 of the first drive scroll member 13 and the first driven scroll wrap 19 of the driven scroll member 17, and the second drive scroll is provided. A second movement space 22 is defined by the second driven scroll wrap 15 of the member 16 and the second driven scroll wrap 20 of the driven scroll member 17 . Also, the first movement space 21 and the second movement space 22 communicate with each other through a through hole 23 formed in the central side of the end plate 18 of the driven scroll member 16 .

Also in accordance with the present invention, the first and second driven scroll wraps 12, 15 and the driven scroll wraps 19, 20 adjust their involute curves so that the first and second While the moving spaces 21 and 22 move from the center side to the vicinity of the outer periphery, the volume is increased and the volume is decreased within a predetermined range of the outermost periphery wrap (270° (3π/2) from the outer periphery). be. Further, the outermost peripheral wrap 12a of the first drive scroll wrap 12 is formed wider than the drive scroll wraps 12b, 15b that control the expansion stroke, as shown in FIGS. 4(a) and 4(e). The outermost peripheral wrap 12a is integrally formed with the first and second driving scroll wraps 12 and 15, and the second driving scroll member 16 has a fitting groove into which the outermost peripheral wrap 12a is fitted. 15a is formed, and the first driving scroll member 13 and the second driving scroll member 16 are connected at their outer peripheral portions.

Accordingly, when the electric motor 60 is driven, the first and second driving scroll members 13 and 16 rotate via the second rotating shaft 8, and at the same time, the driven scroll member 17 rotates via the Oldham ring 28. While rotating together with the first and second driving scroll members 13 and 16, it performs a turning motion relative to the first and second driving scroll members 13 and 16 to move the first and second movement spaces. 21 and 22 move radially outward from the center side to expand their volume. As a result, the moving space 21a on the center side of the first and second moving spaces 21 and 22 expands in volume as shown in FIG. 2(d)→(c)→(a)→(b). Therefore, the fluid can be sucked from the suction port 6, and the moving space 21a moves radially outward to expand its volume from the moving spaces 21b to 21c, thereby reducing the pressure of the moving space 21a on the center side.

In a predetermined range (for example, 270° (3π/2) from the final end) of the outermost peripheral wraps 12a of the first and second drive scroll wraps 12, 15, the first and second movement spaces 21, 22 The movement space 21d located at the outermost circumferential wrap of is formed so as to reduce the volume of the moving space 21d, and has a structure for compressing and discharging the fluid that has been sucked and expanded.

In this way, the first and second moving spaces 21 and 22 are expanded in a predetermined range from the central side to suck the fluid, and the first and second moving spaces 21 and 22 are expanded in a predetermined range on the outer peripheral side. 22 is contracted to compress and discharge the fluid, a reed valve 30 as a check valve mechanism is provided in a discharge hole 29 formed in the outer peripheral portion of the driven scroll member 17, as shown in FIG. It is to be established. This can prevent backflow of the discharged fluid. The discharge hole 29 is positioned near the innermost peripheral side of the outermost peripheral end portion 31 (shown in FIGS. 2 and 3) of the driven scroll wraps 19 and 20 of the driven scroll member 17. The fluid compressed by the outermost peripheral edge 32 (shown in FIG. 2) of the wrap 12a can be reliably discharged. Further, the outermost peripheral end portions 31 of the driven scroll wraps 19 and 20 are formed in an arc shape having a radius R, and this radius R is defined by, for example, 2R=t+2Ror+α. Here, t is the wrap width of the wide drive scroll wrap 12a shown in FIG. is the dimension of the gap. Furthermore, the symbol c shown in FIG. 2(b) indicates the outermost peripheral sealing point of the conventional driven scroll wrap. It made the process possible.

In addition, as described above, the first scroll member 13 and the second scroll member 16 are configured so that the outermost circumferential wrap 12a of the first scroll member 13 passes through the penetrating portion 18a formed in the driven scroll member 17 to the second scroll member 16. Since the two scroll members 16 are connected by being fitted into the fitting grooves 15a of the scroll members 16, a pressure canceling mechanism is formed, and the vacuum pressure can be supported by the strength of the wide outermost circumferential wrap 12a, thereby increasing the strength. It becomes

REFERENCE SIGNS LIST 1 scroll type vacuum pump 2 discharge port 3 working space 4 vacuum pump mechanism 5 housing 6 suction port 7 first rotary shaft 8 second rotary shaft 9, 10, 26, 27 bearing 11 first end plate 12 first drive scroll wrap 13 first drive scroll member 14 second end plate 15 second drive scroll wrap 15a outermost periphery wrap 16 second scroll member 17 driven scroll member 18 end plate 19 first driven scroll wrap 20 second driven scroll Lap 21 first movement space 22 second movement space 23 through hole 24 first driven scroll receiver 25 second driven scroll receiver 29 discharge hole 30 reed valve 40 magnetic fluid seal 50 coupling 60 electric motor

Claims (3)

a housing defining therein a working space communicating with the discharge port; a pair of rotating shafts rotatably held in the housing; and a second driving scroll member, a driven scroll member disposed between the first and second driving scroll members, and first and second driven scrolls rotatably holding the driven scroll member to the housing. first and second driven scroll wraps erected on both sides of the driven scroll member; and a second driven scroll wrap defining first and second travel spaces, wherein
The first and second moving spaces communicate with a suction port formed in one of the rotating shafts on the center side of the rotating shaft, communicate with the working space at the outermost peripheral end, and extend radially outward from the center side. The first and second driven scroll wraps and the first and second drive scroll wraps are arranged to expand their volume toward the direction to suck the fluid, and to reduce their volume in a predetermined range of the outermost wrap to compress and discharge the fluid. A scroll type vacuum pump, characterized in that a second driven scroll wrap is formed . The range in which the volumes of the first and second movement spaces of the outermost circumferential wrap are reduced and the compression is performed is based on the fact that the first and second drive scroll wraps are formed integrally and the maximum of the range in which the compression is performed. 2. The scroll type vacuum pump according to claim 1, wherein the radial width of the outer peripheral wrap is wider than the radial width of the driving scroll wrap that controls expansion from the center side to the vicinity of the outer periphery. 3. The scroll type vacuum pump according to claim 2, wherein a discharge hole is formed in the driven scroll member located at the outermost end of the movement space, and a reed valve is provided as a check valve in the discharge hole. .

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