JP5663797B2 - Rotary pump - Google Patents

Description

  According to the present invention, a rotary shaft including a rotor rotating in a cylinder is supported in a cantilever state by a bearing disposed on one side of the rotor so that a tip end side of the rotary shaft becomes a free end, and gas is supplied to the cylinder. The present invention relates to a rotary pump that exhausts gas compressed by intake air into the cylinder.

  As a rotary pump, there is a claw pump which is a non-contact type vacuum pump equipped with a claw rotor. For example, according to the claw pump exhaust structure and exhaust method previously proposed by the present applicant, the cylinder forming the pump chamber, one side plate that closes the end face of the cylinder, and the other side plate are parallel to each other in the cylinder. The two rotating shafts arranged to be positioned at each other and rotated in opposite directions, and integrally fixed to each of the two rotating shafts, are in contact with each other and inhaled gas Two rotors with hook-shaped claws formed so that they can be compressed, a rotary drive device, an intake port communicating with a portion of the pump chamber where the gas in the cylinder is not compressed, one side plate and the other side plate Both are provided with an exhaust port that opens to a portion of the pump chamber where the gas in the cylinder is compressed (see Patent Document 1). According to this, the pump performance of the claw pump can be improved by increasing the exhaust efficiency.

  In such a claw pump, there is a compression step, and the exhaust efficiency is improved by compressing the intake gas (air). During the reaching operation of such a rotary pump, since there is no intake air amount, in principle, there is no pneumatic transport and compression of the pump, and work as a pump is zero. However, in reality, intake air exists due to leakage from a small gap even during ultimate operation, and the space (sealed space) immediately before the exhaust opening formed by the rotor and cylinder is externally (largely exhausted from the inside of the pump) through the exhaust port. When communicating with a space having air above the atmospheric pressure), the exhaust air above the atmospheric pressure flows back into the pump because the space just before the exhaust opening is negative. The backflowed air is recompressed and discharged to the outside again. Here, useless processes occur, and the power load and the pump internal temperature rise. The ultimate operation is the operation at the ultimate pressure, and the ultimate pressure is when the suction port of the vacuum pump, which is the maximum capacity for creating the vacuum of the pump, is closed (the exhaust flow rate becomes zero). Is the pressure that can be reached.

  That is, according to the exhaust air that flows back into the pump at the time of this reaching operation, the power load increases and the operation efficiency deteriorates. Further, the exhaust air flowing backward increases the internal temperature of the pump, so that deterioration of important parts such as rotor contact, oil seals and bearings due to thermal expansion tends to occur, and the reliability of the pump device is lowered. On the other hand, if the volume immediately before the exhaust opening is simply reduced so as to suppress the amount of backflow air, the air opening side when the exhaust flow rate is high (in the state where the pressure of the sucked air is close to the atmospheric pressure) Is overcompressed). Further, there arises a problem that the flow rate is reduced due to the reduction of the pump internal volume. As long as there is a volume immediately before the exhaust is released, backflow air is always generated, and it becomes a problem to rationally mitigate the above problems. Conventionally, this problem has been dealt with by restricting the operating conditions, and the operating efficiency has not been improved.

Note that the present applicant has previously proposed the following configuration of a rotary vacuum pump (vane pump) having a vane. The vacuum pump is provided with a gas exhaust hole, and the exhaust hole is provided with a first check valve. In addition, a pressure relief hole is provided to release the gas compressed above the atmospheric pressure in the vacuum pump into the outside air, and to reduce the power loss of the vacuum pump, and the pressure relief hole includes A second check valve is provided. The exhaust hole and the pressure relief hole constitute a gas exhaust port of a vacuum pump (see Patent Document 2).
According to this, the escape hole is provided in the peripheral wall part of the wall part which forms a cylinder, and it can suppress that the inside of the pump to be compressed becomes overcompressed and the temperature rises.

JP 2011-38476 A (first page) JP 2001-289167 A ([0020])

The problems to be solved with respect to the rotary pump are to prevent the exhaust gas from flowing back into the pump as much as possible, to improve the operating efficiency and suppress the temperature rise inside the pump, and to prevent the inside of the pump from being overcompressed. A rational configuration for suppression is that no rotary pump has been proposed.
Accordingly, an object of the present invention is to prevent the exhaust gas from flowing back into the pump as much as possible and to prevent the pump from becoming overcompressed as much as possible, to suppress the temperature rise inside the pump and to improve the reliability. An object of the present invention is to provide a rotary pump that can improve operating efficiency.

The present invention has the following configuration in order to achieve the above object.
According to one aspect of the rotary pump according to the present invention, a rotor that is provided on the cantilever end surface side of the rotating shaft and rotates in the cylinder is cantilevered via the rotating shaft by a bearing disposed on one side of the rotor. In the rotary pump that is supported by the gas and sucks compressed gas into the cylinder and exhausts the compressed gas from the cylinder, the cantilever in which the rotating shaft is not inserted among the end wall portions constituting both ends in the axial direction of the cylinder the end wall of the end face, partially relief can escape hole of the compressed gas and opens provided we are in the axial direction of the rotary shaft, from the exhaust port for exhausting the compressed gas in the cylinder And a silencer part that forms a space for silencing the exhaust gas from the exhaust hole and the exhaust gas from the escape hole .

According to one aspect of the rotary pump according to the present invention, a unit pump configuration including the cylinder and the rotor is provided in a plurality of stages in the axial direction of a rotary shaft including a rotor that rotates in the cylinder, and the unit of each stage is provided. Regarding the pump configuration, in the rotary pump that sucks gas into the cylinder and exhausts the compressed gas from the cylinder, the cantilever end side of the rotary shaft in the unit pump configuration of the final stage that compresses the gas to the highest pressure A last stage rotor provided in a cantilever state via the rotary shaft by a bearing disposed between the last stage unit pump structure and the previous unit pump structure, and the last stage unit pump A part of the compressed gas is released to the end wall portion on the free end side where the rotation shaft is not inserted among the end wall portions constituting both ends in the axial direction of the cylinder. An escape hole that can be opened in the axial direction of the rotating shaft is provided, and a space that silences the exhaust gas from the exhaust port that exhausts the compressed gas of the cylinder and the exhaust gas from the escape hole is silenced. The silencer part to be formed is provided .
Moreover, according to one form of the rotary pump which concerns on this invention, the said escape hole can be provided with two or more by the end wall part by the side of the said free end .

Further, according to one aspect of the rotary pump according to the present invention, the relief hole opens when the pressure in the cylinder is higher than a predetermined pressure, and when the pressure in the cylinder is lower than the predetermined pressure. A non-return check valve may be provided.
Moreover, according to one form of the rotary pump which concerns on this invention, the said non-return valve can be a reed valve.

  According to the rotary pump of the present invention, the exhaust gas is prevented from flowing back into the pump as much as possible, and the pump is prevented from being over-compressed as much as possible, and the temperature rise inside the pump is suppressed and reliability is improved. It is possible to improve the operation efficiency, and it is possible to improve the driving efficiency.

It is sectional drawing which shows the example of a form as a high-order concept of the rotary pump which concerns on this invention. It is a perspective view which shows the example of a form of the biaxial rotary pump which concerns on this invention. FIG. 3 is a central cross-sectional view of the embodiment of FIG. 2. It is a center longitudinal cross-sectional view of the form example of FIG. It is XX sectional drawing of the example of a form of FIG. It is a side view which shows the end wall part which removed the muffler case of FIG. It is a side view which shows the state which removed the relief valve of the end wall part of FIG. It is the perspective view which looked at the state which removed the escape box of the example of a form of Drawing 2 from the bottom face side. It is the perspective view which looked at the state which removed the cover part of the connection case of the form example of FIG. 2 from the upper surface side. It is sectional drawing explaining the arrangement | positioning relationship between the two rotors of the example of FIG. 2, and a some escape hole. It is sectional drawing explaining the change of the ratio of the compression state of the gas by the two rotors of the example of FIG. 2, and the opening by several escape holes.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view with reference numerals so as to show an example of a superordinate concept of a rotary pump according to the present invention. First, an example of a superordinate concept of the present invention will be described based on FIG. .

  This embodiment is a positive displacement pump among the rotary pumps, and belongs to the biaxial rotary pump. Examples of the biaxial rotary pump include a claw pump that is a rotor non-contact type pump, a screw pump, and a roots pump. Moreover, there exists a vane pump etc. as a uniaxial rotary pump. Such a rotary pump is driven by, for example, an electric motor and used as a pneumatic device such as a vacuum pump or a blower.

  In this embodiment, the two rotors 30 and 30 are rotated in a non-contact manner while maintaining a minute clearance, and the two rotors 30 and 30 are rotated in a non-contact manner while maintaining a minute clearance on the inner surface of the cylinder 50. As shown, the two rotary shafts 20, 20 including the rotors 30, 30 are supported by the bearings 40, 40, and the compressed gas is discharged from the cylinder 50 by sucking gas into the cylinder 50. It is a biaxial rotary pump.

This biaxial rotary pump is a claw pump, and the rotors 30 and 30 are provided with hook-shaped claw portions (see FIG. 5). In the rotor 30 of this embodiment, two (plural) hook-shaped claw portions are provided. However, the shape of the claw pump rotor is not limited to this. In some cases, the above-described claw portion may be provided. In addition, since the claw pump can compress the gas to a high pressure, the temperature inside the pump tends to rise.
Further, the claw pump of the present embodiment is a multistage in which the unit pump configuration 10 including the cylinder 50 and the two rotors 30 and 30 is provided in a plurality of stages (two stages) in the axial direction of the two rotary shafts 20 and 20. This is a biaxial rotary pump.

For at least one of the plurality of unit pump configurations 10, an escape hole 70 is provided so that a part of the compressed gas can escape to at least one of the end wall portions 52, 52 constituting both ends of the cylinder 50. (Refer to FIGS. 4 and 7) are provided so as to be opened in the axial direction of the rotary shafts 20 and 20.
In this embodiment, a plurality of escape holes 70 (see FIGS. 4 and 7) are provided in the end wall portion 52. Further, an exhaust port for exhausting the compressed gas of the cylinder 50 (rear-stage exhaust gas) into an end wall part (the other end wall part 52D of the rear-stage cylinder (see FIGS. 4 and 7)) provided with the escape hole 70. A mouth 55B (see FIGS. 4 and 7, etc.) is provided.
In addition, forms, such as a shape, a magnitude | size, a quantity, arrangement | positioning, etc. which concern on the escape hole 70 are not limited to this form example. For example, at least a part (plurality) of the large number of escape holes 70 is opened on the inner bottom surface of a groove-shaped recess formed and formed in a groove shape so as to be continuous with the inner surface of the cylinder 50, The plurality of escape holes 70 may be integrated with each other on the inner surface side of the cylinder 50 so as to communicate with the band-shaped recess and function as one large hole. Even in this case, a check valve (reed valve 71), which will be described later, may be individually provided on the outer surface (exhaust side surface) of the cylinder 50 so as to correspond to each relief hole 70.

  According to the escape hole 70, over-compression on the air release side can be suppressed in a rotary pump such as a non-contact type vacuum pump equipped with a claw rotor. Since over-compression can be suppressed, it is possible to increase the compression ratio by reducing the exhaust port (rear exhaust port 55B) so as to reduce the volume immediately before the exhaust is released. By reducing the volume immediately before the exhaust is released, the amount of exhaust gas flowing back into the pump can be suppressed. By controlling the amount of gas that flows backward, it is possible to save energy by reducing the power load during the ultimate operation of the vacuum pump, and to suppress an increase in the internal temperature of the pump during the ultimate operation, thereby suppressing thermal expansion and extending the life of important parts. Can be realized.

Since the relief hole 70 provided in the end wall portion 52 is formed to open in the axial direction of the rotary shafts 20 and 20, the depth thereof is short corresponding to the thickness of the end wall portion 52. The responsiveness as the escape hole 70 is excellent. That is, the overcompressed gas can be exhausted sequentially with a short time lag. In addition, the escape hole 70 can be easily disposed at the optimum position on the surface of the end wall portion 52 and can be provided so as to optimally exert its function.
In addition, by providing a plurality of escape holes 70 in the end wall portion 52, the overcompressed gas can be exhausted in a timely manner in a well-balanced manner during the gas compression process, and its functionality can be further improved.

  Reference numeral 11 denotes an oil bath cover, which is a driving gear 21 integrally fixed to a driving side rotating shaft 20A (see FIG. 3) and a driven gear integrally fixed to a driven side rotating shaft 20B (see FIG. 3). 22 constitutes an oil bath portion. In addition, 11a is an oil gauge and is arrange | positioned so that the amount of lubricating oil in an oil bath part can be confirmed.

  Reference numeral 23 denotes a driven pulley, which is integrally fixed to one end of the drive side rotating shaft 20A. A drive belt is wound around the driven pulley 23 to transmit power from, for example, an electric motor, so that the biaxial rotary pump of this embodiment is driven. The drive force transmission means is not limited to this, and for example, the drive-side rotary shaft 20A and the drive shaft of the electric motor may be arranged in series and coupled by coupling.

In this embodiment, the oil cover 11, the front pump body 12, the front side plate 13, the rear pump body 15, the rear side plate 16, and the muffler case 17 are connected in the axial direction of the rotary shaft 20. An outer shell is provided. The oil bath portion formed by the oil cover 11 of the present embodiment is provided on the power transmission side, and the drive gear 21 and the driven gear 22 are each supported by a bearing 40 in a cantilever manner. The shaft 20 is integrally fixed to the rear end side.
Each cylinder 50 provided in the front-stage pump main body 12 and the rear-stage pump main body 15 is formed by end wall portions 52 and 52 and peripheral wall portions 53 at both ends.

Reference numeral 60 denotes a silencer unit, which exhausts air from an exhaust port (exhaust port 55B (see FIGS. 4 and 7, etc.) at the rear stage) for exhausting the compressed gas of the cylinder 50 and escape holes 70 (see FIGS. 4, 7 and so on). A muffler case 17 is formed as a space for joining and exhausting the exhaust air. According to this, exhaust noise can be effectively merged and silenced.
In other words, the structure of the silencer portion is that normal exhaust from an exhaust port that is always open (for example, the exhaust port 55B at the rear stage), and over-compression prevention exhaust that is exhausted from the relief hole 70 when the check valve 71 is open. The two exhaust systems are combined into a single muffler that silences and has a rational and inexpensive construction.

Next, based on FIGS. 2 to 10, a specific example of a biaxial rotary pump having a multi-stage (two-stage) unit pump configuration according to the present invention, which is a claw pump, will be described.
In the present embodiment, at least one (unit pump configuration 10A) of a plurality (two stages) of unit pump configurations 10A and 10B includes rotors 30A and 30B with respect to two rotating shafts 20A and 20B as shown in FIG. Both ends are supported by arranging bearings 40A, 40B, 40C and 40D on both sides. In addition, according to the present embodiment, the unit pump configuration 10A is arranged at the front stage of the gas flow, and the unit pump configuration 10B is arranged at the rear stage of the gas flow.

  Moreover, in this embodiment, as shown in FIG. 3, at least one (unit pump configuration 10B) located on both end surfaces in the axial direction of the rotation shafts 20A and 20B among the plurality of unit pump configurations 10A and 10B is two The rotary shafts 20A and 20B are configured to be supported in a cantilevered manner by bearings 40C and 40D disposed on one side of the rotors 30C and 30D and adjacent to the unit pump configuration 10A. As the bearings 40C and 40D, angular double row ball bearings can be used.

  According to this, on the basis of the bearings 40C and 40D, the rotors 30A and 30B are arranged on one side, and the rotors 30C and 30D are arranged on the other side. For this reason, the thermal expansion occurs separately on both sides in the axial direction of the rotating shaft with reference to the bearings 40C and 40D. Therefore, the influence of thermal expansion related to the side clearance, which is the clearance between the rotor 30 and the end wall portion 52 of the cylinder, is distributed to one rotor 30A, 30B side and the other rotor 30C, 30D side. For this reason, compared to the conventional multi-stage pump in which a rotary shaft having a plurality of rotors in the axial direction is supported at both ends so that the plurality of rotors are sandwiched between two bearings, the thermal expansion related to the side clearance is reduced. The impact will be small. Therefore, the side clearance can be made smaller, and the occurrence of gas leakage can be made smaller, and the pump performance can be improved.

  Further, in the present embodiment, the final stage rotors 30C and 30D provided on the cantilever end face side of the rotary shafts 20A and 20B in the unit pump configuration 10B of the final stage that compresses the gas to the highest pressure are the final stage. The bearings 40C and 40D arranged between the unit pump configuration 10B and the preceding unit pump configuration 10A are supported in a cantilever state via the rotary shafts 20A and 20B.

That is, the unit pump configuration 10B including the rotors 30C and 30D provided on the rotary shafts 20A and 20B and supported in a cantilever state is a final unit pump configuration that compresses gas to the highest pressure.
When the unit pump configuration 10B is in the final stage as described above, the rotors 30A and 30B of the first unit pump configuration 10A have a large width because a large volume of gas is introduced into the cylinder 50A in the previous stage. It has a large mass and is supported at both ends. The rotors 30C and 30D of the unit pump configuration 10B in the final stage (second stage in this embodiment) are narrow in width and smaller in mass because of the relationship in which the gas is compressed and introduced into the cylinder 50B in the subsequent stage. It is supported in a cantilevered state.
In both end support, since the load is dispersed and it can easily cope with a large mass, the both end support is suitable for the first stage rotors 30A and 30B. Compared to this, the cantilever support is difficult to deal with a large mass, so that the cantilever support is suitable for the rotors 30C and 30D in the final stage having a smaller mass. Therefore, as in this embodiment, a multistage pump structure can be rationally configured.

Further, in the present embodiment, the final stage unit pump configuration 10B is a cantilevered end face side through which the rotary shafts 20A and 20B are not inserted among the end wall parts 52C and 52D constituting both ends of the rear cylinder 50B. An escape hole 70 (see FIGS. 4 and 7, etc.) through which a part of the compressed gas can escape is provided in the end wall portion 52D so as to open in the axial direction of the rotary shafts 20A and 20B.
According to the relief hole 70, even if the exhaust port is made small in order to reduce the volume immediately before the exhaust is released, over-compression on the atmosphere open side can be suppressed. Therefore, the escape hole 70 is an example of a component of an overcompression suppressing mechanism that can suppress overcompression on the atmosphere opening side.

Further, since the rotary shafts 20A and 20B are not inserted into the end wall portion 52D, there are almost no restrictions on the arrangement of the escape holes 70 on the surface of the end wall portion 52D, and the escape holes 70 can be appropriately and easily placed at a required position. Can be provided. This also improves the pump performance.
That is, in the case of a conventional both-end support structure in which the rotary shafts 20A and 20B (shafts) pass through the side plates, even if the relief hole 70 can be arranged, the shaft interferes and the check valve 71 is set to the optimum position. It is difficult to place. On the other hand, when a cantilever support structure in which the shaft does not pass through the side plate is used, the check valve 71 can be suitably arranged and configured without such restriction. If the pump configuration is multistage, the final stage of the multistage pump may be a cantilever support structure that does not allow the shaft to penetrate the side plate.

  The relief hole 70 opens when the pressure in the cylinders 50A and 50B is higher than a predetermined pressure, and closes when the pressure is lower than the predetermined pressure (see FIGS. 4 and 6). ) Is provided. The check valve 71 functions as a backflow suppression mechanism that suppresses exhaust gas that flows back from the escape hole 70 into the high vacuum cylinder. Since the backflow of the exhaust gas into the high vacuum can be prevented as much as possible, the pump efficiency can be improved.

  The check valve of this embodiment is configured by a reed valve 71. The reed valve 71 is formed in a semicircular strip plate shape at the front end, is held and fixed in a cantilever state at the rear end side, and the front end side is a free end so that the relief hole 70 can be opened and closed. Yes. The reed valve 71 is fixed by a check valve fixing bolt 72 that is screwed into the bolt hole 72a. The reed valve 71 is a check valve fixed to the exhaust side of the relief hole 70, and the differential pressure between the pressure on the exhaust side and the pressure in the compression space exceeds the spring force (elasticity) of the reed valve. Open when The check valve using the reed valve 71 has a simple structure, can be configured compactly and inexpensively, can be easily mounted, and can be easily maintained. Further, the check valve is not limited to the reed valve 71 as in the present embodiment, and for example, a check valve that uses an elastic body such as rubber or silicon, or a valve that opens and closes using a spring (spring) is used. Can do.

  The above configuration can also be applied to a single-shaft rotary pump having a single-stage unit pump configuration. That is, the rotor 30 provided on the cantilever end face side of the rotating shaft 20 and rotating in the cylinder 50 is supported in a cantilever state by the bearing 40 disposed on one side of the rotor 30 via the rotating shaft 20, The present invention can also be suitably applied to a rotary pump that exhausts gas compressed into the cylinder 50 by being sucked into the cylinder 50.

Also in this case, part of the compressed gas may be released to the end wall portion 52D on the side of the cantilevered end surface where the rotation shaft is not inserted among the end wall portions 52, 52 constituting both ends in the axial direction of the cylinder 50. A possible escape hole 70 can be provided in the axial direction of the rotary shaft 20.
Since the rotation shaft 20 is not inserted into the end wall portion 52D, there is almost no restriction on the arrangement of the escape holes 70 on the surface of the end wall portion 52D, and the escape holes 70 can be provided appropriately and easily at a required position. it can. This also improves the pump performance.

  The above configuration can also be applied to a single-shaft rotary pump having a multistage unit pump configuration. That is, even when the unit pump configuration 10 including the cylinder 50 and the rotor 30 is provided in a plurality of stages in the axial direction of the rotating shaft 20, the cantilever constituting the final stage cylinder 50B that compresses the gas to the highest pressure. An escape hole 70 can be provided in the end wall portion 52D on the end surface side. This also has the same effect as described above.

  Further, in the present embodiment, an escape hole 70 that allows a part of the compressed gas to escape is provided in the peripheral wall portion 53A (see FIG. 5) of the cylinder constituting the cylinder portion of the cylinder 50A of the preceding stage. Yes. The escape gas from the escape hole 70 is discharged to an escape box 61 provided outside the peripheral wall portion 53A of the cylinder, and further, the escape box outlet 61a (see FIG. 4) and the escape pipe connection port 17c of the muffler case 17 are provided. Is discharged to the silencer unit 60 through an escape pipe 62 connecting between the two. Then, the exhaust gas is silenced by being merged with exhaust gas from exhaust ports 55A and 55B, which will be described later, by the silencer unit 60, and discharged to the outside from the exhaust port 17a (see FIG. 2) of the muffler case.

As described above, the escape hole 70 provided in the peripheral wall portion 53A of the cylinder can also prevent the compression space 51A inside the pump from being overcompressed and improve the pump performance.
However, when the relief hole 70 is provided in the peripheral wall portion 53A of the cylinder, the depth becomes longer than that in the case where it is provided in the end wall portion 52 as described above, so that the responsiveness as the relief hole 70 is slightly inferior. It is done. Further, when the escape hole 70 is provided in the peripheral wall portion 53A of the cylinder, the drilling position is easily restricted, and there are some difficulties compared to the case where the escape wall 70 is provided in the end wall portion 52 as described above. For example, when the rotor width is small, the number of escape holes 70 that can be secured is small and may not be sufficiently applied.

  Further, in the present embodiment, a connection air passage 65 (see FIG. 4) connected from the exhaust port 55A of the preceding unit pump configuration 10A to the intake port (rear intake port 35B) of the subsequent unit pump configuration 10B is configured. The vent passage wall 66a is provided with an escape hole 70 through which a part of the compressed gas can escape. The connection air passage 65 is a connection case formed of a connection case base 66b having a connection case inlet 66c and a connection case outlet 66d, and a lid plate-like portion constituting the air passage wall 66a. The main body 66 is provided.

  The escape gas from the escape hole 70 is discharged into the cover part 67 of the connection case fixed to the outside of the air passage wall part 66a, and further, the escape outlet 67a (see FIG. 4) of the connection case and the muffler case 17 It is discharged to the silencer part 60 via an escape hose 68 (see FIG. 2) that connects the escape hose connection port 17b (see FIG. 2). Then, the exhaust gas is merged with the exhaust gas from the exhaust ports 55A and 55B by the silencer unit 60, muffled, and discharged to the outside from the exhaust port 17a of the muffler case.

  Reference numeral 36 denotes an intake case, and reference numeral 36a denotes an intake port of the intake case, which communicates with the upstream intake port 35A that opens to the upstream unit pump structure 10A. 43 is an oil seal and 45 is a shaft seal.

Next, based on FIG.10 and FIG.11, the example in the case of providing the several escape hole 70 is demonstrated in detail. 10 shows the configuration of the claw pump and the exhaust state, FIG. 11 (a) shows the initial state of the gas compression process in the claw pump of FIG. 10, and FIG. 11 (b) shows the compression of the gas. FIG. 11C shows a state immediately before the end of the gas compression process, in which the exhaust port 55B is closed with a margin by the side surface of the rotor 30C in the middle of the process. Moreover, the arrow described in FIG. 11 has shown the rotation direction of the rotor.
In the present embodiment, the cylinder walls (one end wall 52C of the rear cylinder, the other end wall 52D of the rear cylinder, and the peripheral wall 53B of the rear stage) constituting the cylinder (the rear cylinder 50B) are gas. A plurality of escape holes 70 through which a part of the compressed gas can be released are provided in a portion of the wall portion constituting the compression space in the compression step (a part of the other end wall portion 52D of the rear cylinder). Yes. The escape hole 70 of the present embodiment is provided so as to be opened in the axial direction of the rotation shafts 20A and 20B.

  Then, through the compression process inside the cylinder (the latter cylinder 50B), it faces the cylinder in which a plurality of escape holes 70 are opened with respect to the volume of the compression space that decreases as the compression ratio of the compression process increases. The plurality of escape holes 70 are arranged so that the ratio of the total area gradually increases. That is, the product of the compression ratio of the gas and the total open area of the escape holes gradually increases from the start of compression to the end of compression in the compression process, and maximizes at the end of compression. A plurality of escape holes 70 are arranged. Note that the maximum compression ratio of gas is the ratio of the volume at the moment when compression starts to the volume at the moment when exhaust starts.

  In order to arrange the plurality of escape holes 70 in this way, the area opened by the escape holes 70 in the range closer to the exhaust port 55B becomes larger than the area opened by the escape holes 70 in the range far from the exhaust port 55B. It should be set as follows. Therefore, in the case where a plurality of escape holes 70 having the same size (same diameter) are arranged, it is preferable that the number of the escape holes 70 is increased as the portion is closer to the exhaust port 55B of the end wall portion 52D. . In other words, the closer to the exhaust port 55B, the higher the density at which the escape holes 70 are present. Furthermore, it is also possible to satisfy the above condition by increasing the size of the escape hole 70 in a portion closer to the exhaust port 55B of the end wall portion 52D.

  In this embodiment, the total number of the plurality of escape holes 70 applied to the rear cylinder 50B is provided in the other end wall portion 52D of the rear cylinder. However, as long as the above-described conditions are satisfied, the present invention is not limited to this, and the end walls in which a part of the plurality of escape holes 70 constitute both ends of the cylinder (the front cylinder 50A and the rear cylinder 50B). (At one end wall 52A of the front cylinder, the other end wall 52B of the front cylinder, one end wall 52C of the rear cylinder, and the other end wall 52D of the rear cylinder). Form may be sufficient. Furthermore, through the compression process inside the cylinder 50, the ratio of the total area in which the plurality of escape holes 70 are opened gradually increases with respect to the volume of the compression space that decreases as the compression ratio of the compression process increases. If the above condition is satisfied, a plurality of escape holes 70 may be provided in the peripheral wall portion 53 of the cylinder.

  The check valve 71 attached to the relief hole 70 is provided so as to open in a state where the pressure inside the pump becomes positive before the exhaust port 55B is opened. Here, “positive pressure” means a pressure in which the pressure in the compression space exceeds the pressure on the exhaust side of the escape hole 70, and is not limited to a pressure higher than the atmospheric pressure. When the differential pressure between the pressure on the exhaust side and the pressure in the compression space exceeds the spring force (elasticity) of the check valve (reed valve 71), the reed valve 71 is opened. In the vacuum pump, the sucked negative pressure air is compressed by the claw-shaped rotor, the check valve 71 is opened by positive pressure (pressure at which the check valve 71 operates), and exhaust from the escape hole 70 is performed. Therefore, it is necessary to arrange the escape hole 70 at a position where the inside of the pump becomes a positive pressure in the compression process of the rotary track formed by the rotor shape. Since the compression process proceeds closer to the exhaust port and the inside is in a high pressure state, the check valve 71 is easier to operate, and the longer the compression process time is, the longer the operation time of the check valve 71 is. The over-compression suppressing effect on the open side is great. Further, in this embodiment, the check valve 71 is constituted by a reed valve, and the operating pressure can be changed / adjusted by changing its hardness / thickness.

As described above, by optimally setting the arrangement conditions of the relief holes 70 for suppressing overcompression on the atmosphere opening side, it is possible to maximize the effect of suppressing overcompression on the atmosphere opening side. .
Further, for the escape hole 70, the shape such as the number of holes, the hole diameter, and the chamfering of the holes may be selectively optimized as appropriate.

According to the present embodiment, a rotary pump such as a non-contact type vacuum pump equipped with a claw rotor is provided with a mechanism for suppressing overcompression by the escape hole 70. Regarding the effect of the escape hole 70, attention is paid to the chain of action. This will be described in detail below.
According to this overcompression suppressing mechanism (relief hole 70), it is possible to suppress overcompression on the atmosphere opening side where the exhaust gas flow rate is large (when operation is performed in a state where the pressure of the sucked air is close to atmospheric pressure). The entrance of exhaust gas that flows backward from the escape hole 70 into the vacuum cylinder can be suppressed by a backflow suppression mechanism using a check valve 71 that closes the escape hole 70.

  According to this, since over-compression can be suppressed as described above, it is possible to increase the compression ratio by reducing the exhaust port so as to reduce the volume immediately before the exhaust is opened. By reducing the volume immediately before the exhaust is released, the amount of exhaust gas flowing back into the pump can be suppressed. By suppressing the amount of gas that flows backward, it is possible to suppress an increase in the power load and the temperature inside the pump during the reaching operation of the vacuum pump.

  That is, according to the present embodiment, the volume of the backflow gas can be suppressed by reducing the volume immediately before the exhaust is released, the power load and the temperature increase can be suppressed, and the overcompression suppressing mechanism (relief hole 70) can be opened to the atmosphere. The inside of the cylinder, which is over-compressed on the side and is in a high vacuum, is controlled by the backflow suppression mechanism (check valve 71) to suppress the backflow gas from the escape hole 70, so that the flow rate is not reduced and A high-efficiency pump structure on the high vacuum pressure side that can use the full pressure range of a stage pump can be realized, and the effect can be maximized.

  In order to reduce the volume immediately before the exhaust is released, it is preferable to make the exhaust port small and provide the exhaust port at a position where the air inside the pump is compressed as much as possible. That is, the exhaust port is provided so as to increase the compression ratio. In order to suppress the amount of the exhaust gas flowing backward, there are other methods in which the exhaust from the front-stage pump is pulled by the rear-stage pump by a multistage structure and a check valve is attached to the exhaust port.

  Furthermore, to explain the above effects from the opposite viewpoint, by increasing the compression ratio in order to reduce the volume immediately before the exhaust is released, it is possible to suppress over-compression on the open side where the exhaust flow rate is high as a result. An escape hole 70 is provided as an over-compression suppressing mechanism. In addition, a check valve 71 is provided as a backflow suppression mechanism that suppresses exhaust gas that flows back from the escape hole 70 into the cylinder in a high vacuum.

  As described above, the present invention has been described in various ways with preferred embodiments. However, the present invention is not limited to these embodiments, and many modifications can be made without departing from the spirit of the invention. That is.

10 Unit pump configuration 10A Front unit pump configuration 10B Rear unit pump configuration 11 Oil bath cover 11a Oil gauge 12 Front pump body 13 Front side plate 15 Rear pump body 16 Rear side plate 17 Muffler case 17a Muffler case Exhaust port 17b Escape hose connection port 17c Escape pipe connection port 20 Rotary shaft 20A Drive rotary shaft 20B Driven rotary shaft 21 Drive gear 22 Driven gear 23 Driven pulley 30 Rotor 30A Front drive rotary shaft side rotor 30B Previous driven rotary shaft side Rotor 30C Rear rotor 30D Rear driven rotor side rotor 35A Front air inlet 35B Rear air inlet 36 Air intake case 36a Air intake case air inlet 40 Bearing 40A One drive rotary shaft side shaft 40B Bearing on one driven rotating shaft side 40C Bearing on the other driven rotating shaft side 40D Bearing on the other driven rotating shaft side 43 Oil seal 45 Shaft seal 50 Cylinder 50A Front cylinder 50B Rear cylinder 51A Front compression space 51B Rear stage 52 End wall portion 52A One end wall portion of the front stage cylinder 52B The other end wall portion of the front stage cylinder 52C One end wall portion of the rear stage cylinder 52D The other end wall portion of the rear stage cylinder 53 The peripheral wall portion 53A The front peripheral wall Portion 53B Rear peripheral wall portion 55A Front exhaust port 55B Rear exhaust port 60 Silencer unit 61 Escape box 61a Escape box outlet 62 Escape pipe 65 Connection air passage 66 Connection case body 66a Air passage wall portion 66b Base of connection case Portion 66c Connection case entrance 66d Connection Connection case outlet 67 Connection case cover 67a Connection case escape outlet 68 Escape hose 70 Relief hole 71 Check valve (reed valve)
72 Check valve fixing bolt 72a Bolt hole

Claims (5)

A rotor that is provided on the cantilever end surface side of the rotating shaft and rotates in the cylinder is supported in a cantilever state via the rotating shaft by a bearing disposed on one side of the rotor, and sucks gas into the cylinder. In a rotary pump that exhausts compressed gas from the cylinder,
Of the end wall portions constituting both ends in the axial direction of the cylinder, an end hole on the cantilever end surface side where the rotation shaft is not inserted has an escape hole through which a part of the compressed gas can escape. provided we are open in the axial direction,
A rotary pump, comprising: a silencer section that forms a space for silence by combining exhaust from an exhaust port for exhausting compressed gas of the cylinder and exhaust from the escape hole. A unit pump configuration including the cylinder and the rotor is provided in a plurality of stages in the axial direction of the rotary shaft including a rotor rotating in the cylinder, and gas is sucked into the cylinder for each unit pump configuration in each stage. In a rotary pump that exhausts compressed gas from the cylinder,
In the final stage unit pump configuration for compressing gas to the highest pressure, a final stage rotor provided on the cantilever end side of the rotary shaft is disposed between the final stage unit pump configuration and the previous unit pump configuration. Supported in a cantilevered state via the rotating shaft by a bearing ,
In the final stage unit pump configuration, a part of the compressed gas escapes to the end wall portion on the free end side where the rotating shaft is not inserted among the end wall portions constituting both ends in the axial direction of the cylinder. An escape hole that can open in the axial direction of the rotating shaft,
A rotary pump, comprising: a silencer section that forms a space for silence by combining exhaust from an exhaust port for exhausting compressed gas of the cylinder and exhaust from the escape hole .   The rotary pump according to claim 1 or 2, wherein a plurality of the escape holes are provided in an end wall portion on the free end side.   The relief hole is provided with a check valve that opens when the pressure in the cylinder is higher than a predetermined pressure and closes when the pressure is lower than the predetermined pressure. Item 4. A rotary pump according to any one of Items 1 to 3.   The rotary pump according to claim 4, wherein the check valve is a reed valve.

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