JP2020076370A - Scroll-type vacuum pump - Google Patents

Abstract

To provide a scroll type vacuum pump applying an expansion system not generating compression heat, and having a structure enabling efficient suction/discharge.SOLUTION: A scroll type vacuum pump 1 includes a housing 5 defining an operation space 3 inside thereof, a pair of driving scroll members 13, 16 disposed in the operation space 3, and a driven scroll member 17 disposed between the pair of driving scroll members 13, 16. Moving spaces 21, 22 are defined by driven scroll laps 19, 20 vertically disposed at both sides of the driven scroll member 17, and driving scroll laps 12, 15 of the driving scroll members 13, 16 respectively engaged with the driven scroll laps 19, 20, and the moving spaces 21, 22 may enlarge their volumes from a center side toward an outer peripheral direction, and may reduce the volumes in a prescribed range of an outermost peripheral lap 12a.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a scroll-type vacuum pump that includes a drive scroll member and a driven scroll member, and that changes a partition space defined by the drive scroll member and the driven scroll member to suck gas from an intake port.

  Japanese Patent Application Laid-Open No. 2002-527670 discloses a scroll type vacuum pump. This scroll type vacuum pump is provided with an expander (expander) and a compressor (compressor), which are arranged in series in the same housing as two stages and driven by the same shaft, whereby a re-expansion / compression process is performed. It allows the overheating normally associated with. This patent document 1 discloses that in the scroll type vacuum pump, the first stage is a scroll type expander and the second stage is a scroll type compressor.

Japanese Patent Publication No. 2002-527670

  When the expander is used as a vacuum pump, as disclosed in US Pat. No. 6,037,048, ambient air will re-expand toward the discharge pocket because the air pressure in the discharge pocket is significantly lower than the ambient air pressure. This re-expansion of ambient air consumes energy and causes overheating. Also, when the compressor is used as a vacuum pump and the inlet air of the compressor is at atmospheric pressure due to startup or leakage to the atmosphere, lubrication is usually not performed or internal cooling cannot be performed. The accompanying heat damages the compressor, and the heat of re-expansion and compression causes excessive heat increase in the scroll element, resulting in galling between the tip of the scroll element and the base. Further, the scroll-type vacuum pump disclosed in Patent Document 1 has a two-stage structure including an expander and a compressor, and thus causes a problem that the device itself becomes large.

  Therefore, the present invention is to provide a scroll type vacuum pump having an expansion type that does not generate compression heat and having a structure that enables efficient suction / discharge.

  According to the present invention, a housing that defines an operating space that communicates with a discharge port therein, a pair of rotating shafts that are rotatably held in the housing, and a pair of rotating shafts that are arranged in the operating space and are fixed to the respective rotating shafts. A pair of driven scroll members, 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 moving space is defined by driven scroll wraps standing upright on both sides of the member and driving scroll wraps of respective drive scroll members meshing with the respective driven scroll wraps, At the center side of the shaft, it communicates with a suction port formed on one of the rotating shafts, communicates with the working space at the outermost peripheral end, and expands its volume from the center side toward the outer peripheral direction, thereby providing a predetermined outer peripheral wrap. To reduce its volume in the range.

  As a result, in the above scroll-type vacuum pump, when the rotating shaft is rotated by the external power such as the electric motor, the drive scroll member and the driven scroll member rotate at high speed, and at the same time, the driven scroll member moves relative to the drive scroll member. The fluid sucked from the suction port formed on the rotating shaft is sucked into the moving space where the volume is expanded and depressurized from the center side toward the outer peripheral direction and moves in the outer peripheral direction. However, in the outermost wrap, the volume is reduced and compressed, and the wrap can be discharged from the discharge port through the working space.

  Further, it is preferable that each of the drive scroll wraps is formed to have a wide width in a range where the compression stroke of the outermost peripheral wrap is performed. As described above, the driving scroll wrap and the driven scroll wrap according to the present invention are the outermost wraps (specifically, the range of 270 ° from the outermost end or 3π / 2 [rad] of the driving scroll wrap and the driven scroll wrap. In the range []], the scroll wrap is increased in width to withstand the centrifugal force applied to the outermost wrap and to withstand the pressure when the fluid is compressed.

  It is preferable that a discharge hole is formed in the driven scroll member located at the outermost end of the moving space, and a check valve is provided in the discharge hole. As a result, backflow at the time of discharging the fluid can be prevented, so that the sucked fluid can be reliably discharged. The discharge valve is preferably a reed valve formed so as to cover the discharge hole. Further, the reed valve is preferably installed on the center line of the driven scroll member in order to reduce the influence of centrifugal force.

  It is desirable that the respective drive scroll members be connected at their outer peripheral portions as a pressure canceling mechanism. Specifically, it is desirable that the outer peripheral portion of the drive scroll wrap of the one drive scroll member be fitted into a groove portion formed in a portion corresponding to the other drive scroll member. As a result, the vacuum pressure can be supported by the strength of the drive scroll wrap, so that the strength of the drive scroll member can be increased. Further, with this structure, since the vacuum pressure does not act on the bearing, the life of the bearing can be extended.

  Further, it is desirable to provide a shaft seal or a magnetic fluid seal at the end of the rotary shaft where the suction port is formed, depending on the degree of vacuum achieved. In the above-mentioned structure, only the end of the rotary shaft where the suction port is formed needs to be sealed with a magnetic fluid, for example, so that the structure is simplified and the cost can be reduced.

  According to the present invention, since the gas is sucked while being expanded from the suction port, the compression heat is not generated, so that there is an effect that the cooling mechanism is unnecessary. Further, since only the periphery of the rotary shaft having the suction port needs to be sealed, the structure is simple and the cost can be reduced. Further, since there is only one sealing part, there is an effect that a high vacuum can be obtained. Further, even if the fluid is a condensable gas such as water vapor, it can be separated by centrifugal force, so that a mechanism such as a gas ballast is not required. Further, the pressure canceling mechanism has an effect that the vacuum pressure does not act on the bearing. Furthermore, since the vacuum portion is only the moving space on the center side, the ultimate vacuum can be obtained quickly.

It is a section explanatory view showing composition of a scroll type vacuum pump concerning an example of the present invention. It is explanatory drawing which showed the state of expansion and compression which concerns on the Example of this invention. It is explanatory drawing which showed the check valve structure which concerns on the Example of this invention. It is explanatory drawing which showed the pressure cancellation mechanism which concerns on an Example in this 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 a housing 5 which defines an operating space 3 communicating with the discharge port 2 therein. . A vacuum pump mechanism 4 is arranged in the working space 3. Further, the housing 5 includes a cylindrical side surface portion 5a provided with the discharge port 2 and a housing lid portion 5b for rotatably holding the first rotary shaft 7 having the suction port 6 via a bearing 9. For example, it is configured by a housing bottom portion 5c that rotatably supports a second rotating shaft 8 connected to an external power such as an electric motor 60 via a bearing 10. A shaft seal and a magnetic fluid seal 40 are provided at the end of the first rotary shaft 7 depending on the degree of vacuum achieved. The second rotating shaft 8 and the electric motor 60 are connected via a coupling 50.

  A first end plate 11 is integrally formed on the first rotary shaft 7, and a side surface of the first end plate 11 opposite to the first rotary shaft 7 extends radially outward from the center. A first drive scroll wrap 12 is provided that extends spirally. The first rotary shaft 7, the first end plate 11 and the first drive scroll wrap 12 constitute a first drive scroll member 13. Further, a second end plate 14 is integrally formed on the second rotating shaft 8, and a side surface of the second end plate 14 opposite to the second rotating shaft 8 is radially outward from the center direction. A second drive scroll wrap 15 is provided which extends spirally towards. The second rotary shaft 8, the second end plate 14, and the second drive scroll wrap 15 constitute a second drive scroll member 16.

  A driven scroll member 17 is disposed 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 that spirally expand outward from the center in the radial direction on both sides of the end plate 18. Further, the driven scroll member 17 has first and second driven scroll receivers 24 and 25 connected to each other at an outer peripheral portion thereof, and the first driven scroll receiver 24 is rotated by a bearing 26 to the housing lid portion 5b. The second driven scroll receiver 25 is rotatably supported by the housing bottom portion 5c via a bearing 27. An Oldham ring 28 for preventing the driven scroll member 17 from rotating is provided between the driven scroll receiver 25 and the second end plate 14 of the second drive scroll member 16.

  With this configuration, 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 define the first moving space 21 and the second drive scroll. A second moving space 22 is defined by the second driven scroll wrap 20 of the second drive scroll wrap 15 of the member 16 and the second driven scroll wrap 20 of the driven scroll member 17 of the member 16. Further, the first moving space 21 and the second moving space 22 communicate with each other through a through hole 23 formed on the center side of the end plate 18 of the driven scroll member 16.

  Further, according to the present invention, the first and second drive scroll wraps 12 and 15 and the driven scroll wraps 19 and 20 have their involute curves adjusted to define the first and second scroll wraps defined by them. While the moving spaces 21 and 22 move from the center side to the vicinity of the outer circumference, the volume thereof is expanded and at the same time, the volume thereof is reduced within a predetermined range (270 ° (3π / 2) from the outer circumferential end) of the outermost circumferential lap. is there. Further, as shown in FIGS. 4A and 4E, the outermost peripheral wrap 12a of the first drive scroll wrap 12 is formed wider than the drive scroll wraps 12b and 15b that control the expansion stroke. The outermost peripheral wrap 12a is formed by integrally forming the first and second drive scroll wraps 12 and 15, and the second scroll member 16 has a fitting groove 15a into which the outermost peripheral wrap 12a is fitted. Is formed, and the first scroll member 13 and the second scroll member 16 are connected at their outer peripheral portions.

  As a result, when the electric motor 60 is driven, the first and second drive scroll members 13, 16 rotate via the second rotating shaft 8 and, at the same time, the driven scroll member 17 moves through the Oldham ring 28. While rotating together with the first and second drive scroll members 13 and 16, the orbiting motion is relatively performed with respect to the first and second drive scroll members 13 and 16, and the first and second moving spaces 21, 22 move from the center side outward in the radial direction to expand the volume thereof. As a result, the volume of the moving space 21a on the center side of the first and second moving spaces 21 and 22 is expanded as shown in (d) → (c) → (a) → (b) of FIG. Therefore, the fluid can be sucked from the suction port 6, and the moving space 21a moves radially outward to increase the volumes of the moving spaces 21b to 21c and depressurize 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 wrap 12a of the first and second drive scroll wraps 12 and 15, the first and second moving spaces 21 and 22 are provided. Is formed so as to reduce the volume of the moving space 21d located in the outermost peripheral wrap, and has a structure for compressing and discharging the fluid that has been sucked and expanded.

  As described above, the first and second moving spaces 21, 22 are expanded in a predetermined range from the center side to suck the fluid, and the first and second moving spaces 21, 22 are moved in a predetermined range on the outer peripheral side. As shown in FIG. 3, a reed valve 30 as a check valve mechanism is provided in the discharge hole 29 formed in the outer peripheral portion of the driven scroll member 17, as shown in FIG. It is provided. This can prevent backflow of the discharged fluid. The discharge hole 29 is located near the innermost peripheral side of the outermost peripheral end portions 31 (shown in FIGS. 2 and 3) of the driven scroll wraps 19 and 20 of the driven scroll member 17, whereby the drive scroll is formed. The fluid compressed by the outermost peripheral end 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 the radius R is defined by, for example, 2R = t + 2Ror + α. Here, t is the wrap thickness of the wide drive scroll wrap 12a shown in FIG. 2A, Ror is the orbiting radius of the outermost peripheral end 32 of the drive scroll wrap 12a, and α is This is the size of the minute gap. Further, reference numeral c shown in FIG. 2 (b) indicates the outermost peripheral seal point of the conventional driven scroll wrap. In the present invention, the outermost peripheral end portion 32 is extended by π to enable the compression stroke. It was done.

  In addition, as described above, in the first scroll member 13 and the second scroll member 16, the outermost peripheral wrap 12a of the first scroll member 13 is formed through the penetrating portion 18a formed in the driven scroll member 17 and Since the second scroll member 16 is connected by being fitted in the fitting groove 15a of the scroll member 16, a pressure canceling mechanism is formed, and the vacuum pressure can be supported by the strength of the outermost peripheral wrap 12a formed to be wide, and the strength can be increased. It will be.

1 Scroll Type Vacuum Pump 2 Discharge Port 3 Working Space 4 Vacuum Pump Mechanism 5 Housing 6 Suction Port 7 First Rotating Shaft 8 Second Rotating 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 peripheral wrap 16 Second scroll member 17 Driven scroll member 18 End plate 19 First driven scroll wrap 20 Second driven scroll Wrap 21 First moving space 22 Second moving 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 (4)

A housing defining an operating space communicating with the discharge port therein, a pair of rotating shafts rotatably held in the housing, and a pair of rotating shafts arranged in the operating space and fixed to the rotating shafts. A drive scroll member, a driven scroll member arranged between the pair of drive scroll members, and a pair of driven scroll receivers that rotatably hold the driven scroll member in the housing. In a scroll type vacuum pump in which a moving space is defined by an upright driven scroll wrap and a drive scroll wrap of each drive scroll member that meshes with each driven scroll wrap,
The moving space communicates with a suction port formed on one of the rotating shafts on the center side of the rotating shaft, communicates with the working space at the outermost peripheral end, and expands its volume from the center side toward the outer peripheral direction. The scroll-type vacuum pump is characterized in that its volume is reduced in a predetermined range of the outermost wrap.   The scroll type vacuum pump according to claim 1, wherein each of the drive scroll wraps has a wide width in a range where a compression stroke of the outermost wrap is performed.   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 moving space, and a check valve is provided in the discharge hole.   The scroll type vacuum pump according to any one of claims 1 to 3, wherein each of the drive scroll members is connected at its outer peripheral portion as a pressure canceling mechanism.

Images