Oil rotary vacuum pump

Abstract

To provide an oil rotary vacuum pump capable of easily performing failure determination from the outside.SOLUTION: An oil rotary vacuum pump according to an embodiment includes a casing, a pump body, a backflow prevention mechanism, an oil pressure generating unit, and an oil pressure detecting unit. The casing has an intake port, an exhaust port, and an oil reservoir chamber for reserving lubricating oil. The pump body has a pump chamber having a rotating body for transferring gas sucked from the intake port toward the exhaust port. The backflow prevention mechanism has a check valve provided between the intake port and the pump chamber, and a valve chamber for movably supporting the check valve between a first position at which the intake port is opened and a second position at which the intake port is closed. The oil pressure generating unit includes a hydraulic pump which pressure-feeds the lubricating oil from the oil reservoir chamber to the pump chamber interlockingly with driving of the rotating body and supplies an oil pressure for holding the check valve at the first position to the valve chamber. The oil pressure detecting unit detects the oil pressure in the valve chamber.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to an oil rotary vacuum pump equipped with a function for preventing backflow of pump oil. [Background technology]

[0002] An oil-sealed rotary vacuum pump performs the desired pumping function by sucking in, compressing, and discharging gas in a vacuum chamber through an intake pipe while rotating a rotor in the pump chamber. In this case, pump oil is used to lubricate the rotor that slides on the inner circumferential surface of the pump chamber and to ensure a certain level of sealing function in the pump chamber. However, if the oil-sealed rotary vacuum pump is stopped while the vacuum chamber is kept under vacuum, the pump oil in the pump chamber may flow back into the intake pipe and the vacuum chamber as the pressure in the pump chamber increases, causing contamination of these. To address this issue, a check valve is known that blocks the intake port to prevent the backflow of pump oil when the vacuum pump is stopped.

[0003] For example, Patent Document 1 discloses an inlet valve as a check valve having a valve member that is movable between a first position that blocks the inlet and a second position that opens the inlet, and is configured so that when the vacuum pump is operating, the valve member is moved to the second position by oil pressure from the oil pump supplied via an oil line, and when the vacuum pump is stopped, the oil line is cut off and the valve member is moved to the first position by the biasing force of a spring. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 6-200889 Summary of the Invention [Problem to be solved by the invention]

[0005] Conventionally, in this type of oil-sealed rotary vacuum pump, when the operating oil-sealed rotary vacuum pump stops, there has been a problem that it is difficult to externally determine whether the cause of the stop is due to a failure. For example, although it is possible to externally determine a failure based on the motor current value, since the current setting value serving as the criterion for failure determination often varies depending on the motor and the model, it is necessary to determine the current setting value for each motor and model. On the other hand, in the case of a magnetic coupling pump, when out-of-phase occurs, although the pump head side has stopped, the motor remains rotating normally, making it difficult to determine a failure based on the motor current value.

[0006] In view of the above circumstances, an object of the present invention is to provide an oil-sealed rotary vacuum pump capable of easily performing failure determination from the outside.

Means for Solving the Problem

[0007] The oil-sealed rotary vacuum pump according to one embodiment of the present invention includes a casing, a pump body, a backflow prevention mechanism, a hydraulic pressure generation unit, and a hydraulic pressure detection unit. The casing has an intake port, an exhaust port, and a storage chamber for storing lubricating oil. The pump body has a pump chamber having a rotating body that transfers the gas sucked from the intake port toward the exhaust port. The backflow prevention mechanism includes a backflow prevention valve provided between the intake port and the pump chamber, and a valve chamber that movably supports the backflow prevention valve between a first position for opening the intake port and a second position for closing the intake port. The hydraulic pressure generation unit includes a hydraulic pump that pumps the lubricating oil from the storage chamber to the pump chamber in conjunction with the drive of the rotating body, and supplies hydraulic pressure for holding the backflow prevention valve in the first position to the valve chamber. The hydraulic pressure detection unit detects the hydraulic pressure in the valve chamber.

[0008] In the above oil-sealed rotary vacuum pump, since it is provided with a hydraulic pressure detection unit that detects the hydraulic pressure in the valve chamber of the backflow prevention mechanism, for example, it is possible to determine the presence or absence of a failure of the pump based on whether the detected hydraulic pressure is equal to or higher than a reference value.

[0009] The hydraulic pressure generating unit may have an oil supply passage that connects the reservoir chamber and the pump chamber, and a hydraulic pressure introduction passage that connects the reservoir chamber and the valve chamber. The hydraulic pressure detecting unit may include a pressure sensor attached to the casing, and a hydraulic pressure detection line that connects the hydraulic pressure introduction passage and the pressure sensor.

[0010] The hydraulic pressure detection unit may further include a determination unit that determines a drive state of the pump body based on an output of the pressure sensor.

[0011] The hydraulic pressure generating unit may further include a hydraulic pressure discharge passage that connects the hydraulic pressure introduction passage and the reservoir chamber, and a first check valve that is provided in the hydraulic pressure discharge passage and controls the flow of the lubricating oil in a forward direction from the valve chamber side to the reservoir chamber side. The first check valve may be a hydraulic pressure regulating valve that opens when the hydraulic pressure in the valve chamber is equal to or higher than a predetermined value.

[0012] The hydraulic pressure generating section may further include an auxiliary flow passage provided between the hydraulic pressure introduction flow passage and the reservoir chamber and bypassing the hydraulic pressure discharge flow passage. The auxiliary flow passage may include a throttle passage having a flow passage cross-sectional area smaller than a flow passage cross-sectional area of ​​the first check valve when the first check valve is open.

[0013] The hydraulic pressure generating unit may further include a second check valve that is provided in the hydraulic pressure introduction passage and allows the lubricating oil to flow from the valve chamber and the hydraulic pressure introduction passage to the reservoir chamber when the hydraulic pressure in the valve chamber and the hydraulic pressure introduction passage is less than the predetermined value.

[0014] The oil pressure generating section may further include a third check valve that is provided in the oil supply passage and directs the flow of the lubricating oil in a forward direction from the reservoir chamber side to the pump chamber side.

[0015] The check valve mechanism may further include a biasing member disposed in the valve chamber and configured to bias the check valve toward the second position. Effect of the Invention

[0016] According to the present invention, a malfunction of an oil rotary vacuum pump can be easily determined from the outside. [Brief description of the drawings]

[0017] [Figure 1] 1 is a perspective view of a main part of an oil rotary vacuum pump according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a schematic cross-sectional side view of the oil rotary vacuum pump. [Diagram 3] FIG. 2 is an explanatory diagram of a hydraulic circuit constituting the above-mentioned oil rotary vacuum pump, showing the state of the pump during operation. [Figure 4] 3A and 3B are enlarged views of the main part of the backflow prevention mechanism shown in FIG. 2, in which (A) shows the backflow prevention function inactive, and (B) shows the backflow prevention function active. [Diagram 5] FIG. 2 is an explanatory diagram of a hydraulic circuit constituting the oil rotary vacuum pump, showing a state when the pump is stopped. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0019] Fig. 1 is a perspective view of a main part of an oil rotary vacuum pump 1 according to an embodiment of the present invention, and Fig. 2 is a schematic side cross-sectional view thereof. Fig. 3 is an explanatory diagram of a hydraulic circuit constituting the oil rotary vacuum pump 1, showing the state of the pump 1 during operation. In Fig. 1 and Fig. 2, the X-axis, Y-axis, and Z-axis indicate three axial directions perpendicular to each other, the X-axis and Y-axis indicate the horizontal direction, and the Z-axis indicates the height direction.

[0020] [Overall configuration] The oil rotary vacuum pump 1 of this embodiment includes a casing 10, a drive unit 20, a pump body 30, a backflow prevention mechanism 40, a hydraulic pressure generating unit 50, and a hydraulic pressure detecting unit 60.

[0021] (Casing) The casing 10 has a first casing 101 and a second casing 102 .

[0022] The first casing 101 constitutes a main part of the casing 10, and is supported by the base 2. The first casing 101 has a valve accommodating section 14 that accommodates a check valve 41, which will be described later, and accommodates a flow path forming member 15 that forms various passages that communicate with the check mechanism 40.

[0023] The second casing 102 is attached to one end (the left side in FIG. 2) of the first casing 101, and houses the pump body 30, while having a storage chamber 13 that stores pump oil (lubricating oil) O. A level gauge 103 (see FIG. 1) for checking the liquid level Ps of the pump oil O in the storage chamber 13 is attached to a predetermined position of the second casing 102.

[0024] The casing 10 has an intake pipe 11 and an exhaust pipe 12. The intake pipe 11 is attached to an intake port P1 provided in the first casing 101, and is connected to a vacuum chamber or the like via an intake pipe connection part (not shown). The exhaust pipe 12 is attached to an exhaust port P2 provided in the second casing 102, and is an exhaust passage that communicates the storage chamber 13 with the outside air, and discharges the gas G sucked in by the pump body 30 via the intake pipe 11 to the outside of the device. The exhaust pipe 12 is connected to an exhaust pipe connection part (not shown), or the like.

[0025] (Drive unit) The driving unit 20 is composed of a motor that drives the pump body 30, a motor case that houses the motor, and the like, and is attached to the casing 10 (first casing 101). The driving unit 20 has a rotating shaft 21 extending in the X-axis direction, and rotates the rotating shaft 21 about its axis. The rotating shaft 21 may be a shaft member connected to a driving shaft of the motor. In this case, the shaft member may be directly connected to the driving shaft, or may be connected to the driving shaft via a rotation transmission mechanism such as a magnetic coupling, a belt, or a gear. The rotating shaft is rotatably supported by, for example, a sliding bearing or the like.

[0026] (Pump body) The pump body 30 is a two-stage Goethe type pump unit. As shown in FIG.

[0027] The first pump body 31 includes a first pump chamber 311 and a first rotor 312 disposed eccentrically within the first pump chamber 311. The rotating shaft 21 is inserted into the first rotor 312, and a vane 313 is attached so as to slide on the inner periphery of the first pump chamber 311, and the first pump chamber 311 is divided into a plurality of spaces by the vane 313 (see FIG. 3).

[0028] Similarly, the second pump body 32 includes a second pump chamber 321 and a second rotor 322 disposed eccentrically within the second pump chamber 321. The rotary shaft 21 is inserted into the second rotor 322, and a vane 323 is attached to slide on the inner periphery of the second pump chamber 321, and the second pump chamber 321 is divided into a plurality of spaces by the vane 323.

[0029] The first pump body 31 and the second pump body 32 are fixed integrally within the second casing 102. The first rotor 312 and the second rotor 322 are journalled on the rotating shaft 21 so as to rotate within the first pump chamber 311 and the second pump chamber 321.

[0030] The flow path forming member 15 is provided with a first gas introduction path 34 communicating with the first pump chamber 311 and the valve housing portion 14, and the first pump body 31 is provided with a first gas discharge path 35 communicating with the first pump chamber 311 and the storage chamber 13. The second pump body 32 is provided with a second gas introduction path 36 communicating with the first pump chamber 311 and the second pump chamber 321, and a second gas discharge path 37 communicating with the second pump chamber 321 and the storage chamber 13.

[0031] The first rotor 312 and the second rotor 322 correspond to the "rotating body" of the present invention that transfers gas sucked from the intake port P1 toward the exhaust port P2, and the first pump chamber 311 and the second pump chamber 321 correspond to the "pump chamber" of the present invention that houses the above-mentioned rotating body.

[0032] The first gas discharge path 35 and the second gas discharge path 37 are each provided with a discharge valve 38. Each discharge valve 38 is a reed valve having one end supported by the first pump body 31 and the second pump body 32, respectively, and is configured to open when the pressure of the gas compressed in each of the first and second pump chambers 311 and 321 exceeds a predetermined value (atmospheric pressure).

[0033] A gas flow path is formed in the flow path forming member 15, the first pump body 31, and the second pump body 32, which includes the intake port P1, the valve housing portion 14, the first gas introduction path 34, the second gas introduction path 36, the first gas discharge path 35, the second gas discharge path 37, the storage chamber 13, and the exhaust port P2. As a result, when the first rotor 312 and the second rotor 322 are driven, gas is introduced from the intake port P1, and the gas is introduced into the first pump chamber 311 via the valve housing portion 14 and the first gas introduction path 34. A part of the gas is compressed by the rotation of the first rotor 312 and is discharged to the outside from the exhaust port P2 via the first gas discharge path 35 and the storage chamber 13. The remainder of the gas is introduced into the second pump chamber 321 via the second gas inlet passage 36, compressed by the rotation of the second rotor 322, and discharged to the outside from the exhaust port P2 via the second gas exhaust passage 37 and the storage chamber 13.

[0034] (Hydraulic pressure generating section) The hydraulic pressure generating section 50 includes a hydraulic pump 51. The hydraulic pump 51 is typically a trochoid pump having an inner rotor (internal teeth) 51a fixed to the tip of the rotating shaft 21 and an outer rotor (external teeth) 51b meshing with the inner rotor 51a. The hydraulic pump 51 has a pump case 53 that rotatably supports the inner rotor 51a and the outer rotor 51b. The pump case 53 is attached to the second pump body 32 via an attachment member 55 and fixed by a pressing member 56. The hydraulic pump 51 is configured to operate in conjunction with the first rotor 312 and the second rotor 322.

[0035] A lubricating oil introduction passage 54 is formed in the pump case 53, which communicates the hydraulic pump 51 with the bottom of the storage chamber 13. The lubricating oil introduction passage 54 opens to the lower part of the pump case 53, and the pump oil O stored in the storage chamber 13 by the rotation of the hydraulic pump 51 is sucked into the hydraulic pump 51 via the lubricating oil introduction passage 54. The pump oil O sucked into the hydraulic pump 51 is pumped to the lubricating oil passages 57 formed in the pump case 53, the mounting member 55, the second pump body 32, and the first pump body 31, respectively, and is supplied to the rotating shaft 21 and the first and second pump chambers 311 and 312. The lubricating oil passage 57 corresponds to the "oil supply passage" of the present invention, which connects the storage chamber 13 with each of the pump chambers 311 and 312.

[0036] The hydraulic pump 51 is also driven by driving the pump body 30 (first pump body 31, second pump body 32). Operation of this hydraulic pump 51 supplies pump oil O to the first pump chamber 311, the second pump chamber 321 and the rotating shaft 21, thereby lubricating the rotors 312, 322 sliding on the inner circumferential surfaces of the pump chambers 311, 321 and ensuring a certain level of sealing function within the pump chambers 311, 321. This allows the first and second pump bodies 31, 32 to operate smoothly, and the capacity of the oil rotary vacuum pump 1 is stably provided.

[0037] The hydraulic pressure generating section 50 further has a first hydraulic pressure introduction flow passage 58 and a second hydraulic pressure introduction flow passage 59 that communicate between the storage chamber 13 and the valve chamber 42 of the backflow prevention mechanism 40. The first hydraulic pressure introduction flow passage 58 is formed across the pump case 53, the mounting member 55, the second pump body 32, the first pump body 31, and the flow passage forming member 15. The second hydraulic pressure introduction flow passage 59 is formed in the flow passage forming member 15 and communicates between the first hydraulic pressure introduction flow passage 58 and the valve chamber 42. The pump oil O in the storage chamber 13 sucked through the lubricating oil introduction passage 54 by the drive of the hydraulic pump 51 is supplied to the valve chamber 42 through the hydraulic pressure introduction passage 58, and the backflow prevention valve 41 of the backflow prevention mechanism 40 is maintained in an open state (see FIG. 4(A)), as described later.

[0038] (backflow prevention mechanism) Next, a description will be given of the backflow prevention mechanism 40. Fig. 4 is an enlarged view of a main part of the backflow prevention mechanism 40 shown in Fig. 2, where (A) shows the backflow prevention function inactive and (B) shows the backflow prevention function active.

[0039] The check valve 40 has a check valve 41 and a valve chamber 42. The check valve 41 is disposed in a valve housing portion 14 provided between the intake port P1 and the first pump chamber 311. The valve chamber 42 supports the check valve 41 movably between a first position (FIG. 4(A)) where the intake port P1 is opened and a second position (FIG. 4(B)) where the intake port P1 is closed.

[0040] The check valve 41 has a valve body 411 located in the valve housing portion 14, a leg portion 412 located in the valve chamber 42, and a shaft portion 413 connecting the valve body 411 and the leg portion 412. The shaft portion 413 is slidably inserted into a through hole 44a formed in a valve chamber forming member 44 that separates the valve housing portion 14 and the valve chamber 42.

[0041] The valve body 411 has a disk shape, and is provided on its periphery with an annular valve portion 41a that protrudes toward the intake port P1. The valve portion 41a is formed in an annular shape with a diameter larger than the opening diameter of the intake port P1. The inner surface of the first casing 101, near the periphery of the intake port P1, is formed as a valve seat 43 that comes into contact with the valve portion 41a when the check valve 41 moves to the second position (FIG. 4(B)).

[0042] The leg portion 412 is formed in a cylindrical shape that is slidable against the inner wall surface of the cylindrical valve chamber 42. The valve chamber 40 is defined between the valve chamber forming member 44 and the leg portion 412 of the check valve 41, and is in communication with the second hydraulic pressure introduction flow path 59.

[0043] The check valve 41 is urged toward the second position (FIG. 4(B)). ...

[0044] In this way, during operation of the oil rotary vacuum pump 1, the backflow prevention mechanism 40 receives hydraulic pressure from the hydraulic pump 51 linked to the pump body 30 to the valve chamber 42, and moves the backflow prevention valve 41 to the valve open position (first position) shown in Fig. 4(A) against the biasing force of the biasing member 45. This allows communication between the intake port P1 and the pump chambers (the first pump chamber 311 and the second pump chamber 321), making it possible to perform the desired vacuum evacuation operation.

[0045] On the other hand, when the oil rotary vacuum pump 1 is stopped, the introduction of hydraulic pressure from the hydraulic pump 51 to the valve chamber 42 is stopped, and the check valve 41 moves to the valve closed position (second position) shown in Fig. 4(B) by the biasing force of the biasing member 45. This blocks communication between the intake port P1 and the pump chambers (first pump chamber 311 and second pump chamber 321), making it possible to prevent the pump oil in the pump chambers from flowing back to the intake port P1 as the pressure in the pump chambers increases.

[0046] (Oil pressure detector) The hydraulic pressure detection unit 60 is configured to be capable of detecting the hydraulic pressure in the valve chamber 42. The hydraulic pressure detection unit 60 includes a pressure sensor 61 attached to the first casing 101, and a hydraulic pressure detection line 62 connecting the second hydraulic pressure introduction passage 59 and the pressure sensor 61 (see FIG. 3).

[0047] The hydraulic pressure detection line 62 is provided in the flow passage forming member 15, and inputs the hydraulic pressure introduced into the valve chamber 42 to the pressure sensor 61. The pressure sensor 61 is attached to the outer surface of the side wall of the first casing 101 (see FIG. 1), and measures the hydraulic pressure input via the hydraulic pressure detection line 62. Note that the hydraulic pressure detection line 62 is not limited to being connected to the second hydraulic pressure introduction flow passage 59, and may be connected to the first hydraulic pressure introduction passage 58 or to the valve chamber 42. In other words, the position at which the hydraulic pressure detection line 42 is provided is not particularly limited as long as it is on a hydraulic line that has the same pressure as the valve chamber 42.

[0048] The hydraulic pressure detection unit 60 further includes a determination unit 63 that determines the operating state of the pump body 30 (first pump body 31 and second pump body 32) based on the output of the pressure sensor 61 (see FIG. 1). The determination unit 63 stores, for example, the hydraulic pressure in the valve chamber 42 required for the check valve 41 to maintain the closed state (FIG. 4(B)) as a reference value, and determines whether the measured value of the pressure sensor 61 is equal to or greater than the reference value. When it is determined that the measured value is equal to or greater than the reference value, it can be determined that the pump body 30 is operating, and when it is determined that the measured value is less than the reference value, it can be determined that the operation of the pump body 30 has stopped.

[0049] The oil pressure detection unit 60 may further have a display unit that displays the result of the determination by the determination unit 63 to the outside. This allows the user to check from the outside whether the oil rotary vacuum pump 1 is operating or stopped, and allows the operating state to be constantly monitored. In addition, it also becomes easy to check whether the oil rotary vacuum pump 1 has a malfunction.

[0050] The display unit may be configured as a device separate from the hydraulic pressure detection unit 60. Similarly, the determination unit 63 may be configured as a device separate from the hydraulic pressure detection unit 60. In this case, the measurement result of the pressure sensor 61 is transmitted to the determination unit 63 by wire or wirelessly.

[0051] Conventionally, in this type of oil rotary vacuum pump, when the oil rotary vacuum pump stops during operation, it is difficult to judge from the outside whether the cause of the stop is a malfunction. For example, it is possible to judge a malfunction from the outside based on the motor current value, but since the current setting value that is the basis for malfunction judgment often differs depending on the motor and the model, it is necessary to determine the current setting value for each motor and the model. On the other hand, in the case of a magnetic coupling pump, when a step-out occurs, the pump head side stops but the motor continues to rotate normally, so it is difficult to judge a malfunction based on the motor current value.

[0052] In contrast, according to this embodiment, since the pressure sensor 61 that detects the pressure in the valve chamber 42 via the pressure detection line 61 is provided, it is possible to easily determine whether or not there is a malfunction in the oil rotary vacuum pump 1 based on whether or not the detected oil pressure is equal to or greater than the above-mentioned reference value. In particular, in the case of a magnetic coupling pump, it can be determined that step-out has occurred if the detection value of the pressure sensor 61 is less than the above-mentioned reference value.

[0053] [Other configurations of the hydraulic pressure generating section] 3, the hydraulic pressure generating section 50 further includes a first check valve V1, a second check valve V2, and a third check valve V3. The first to third check valves V1 to V3 are provided, for example, in the flow path forming member 15. However, without being limited thereto, some of the first to third check valves V1 to V3 may be provided in the first pump body 31 or the second pump body 32.

[0054] The first to third check valves V1 to V3 are valve devices whose open / closed states are switched between when the oil rotary vacuum pump 1 is operating and when it is stopped, and Fig. 3 shows the state when the pump 1 is operating. On the other hand, Fig. 4 shows the open / closed states of the first to third check valves V1 to V3 when the pump 1 is stopped.

[0055] (First check valve) The first check valve V1 is provided in a hydraulic pressure discharge passage 59A that connects the second hydraulic pressure introduction passage 59 and the reservoir chamber 13. In this embodiment, the hydraulic pressure discharge passage 59A is configured as a part of the second hydraulic pressure introduction passage 59, but is not limited to this, and a hydraulic pressure discharge passage may be provided in the first hydraulic pressure introduction passage 58.

[0056] The first check valve V1 is a valve device that allows the flow of pump oil O in the forward direction from the valve chamber 42 side to the storage chamber 13 side, and more specifically, is a hydraulic pressure regulating valve that opens when the hydraulic pressure in the valve chamber 42 is equal to or higher than a predetermined value.

[0057] As described above, the check valve 41 is maintained in the open state shown in Fig. 4(A) by receiving hydraulic pressure from the hydraulic pump 51 that is introduced into the valve chamber 42. Meanwhile, since the hydraulic pump 51 is linked to the driving of the pump body 30, hydraulic pressure from the pump 51 continues to be introduced into the valve chamber 42 at all times when the oil rotary vacuum pump 1 is in operation. In general, if the hydraulic pressure in the valve chamber exceeds a pressure value sufficient to maintain the check valve in the open state, problems such as damage to the check valve, such as deformation, a decrease in pump performance due to an increase in the load on the pump body, and further, when a magnetic coupling is used to connect the pump body and the driving unit, problems such as loss of synchronization may occur.

[0058] Therefore, in this embodiment, the first check valve V1 functions as a relief valve, and when the hydraulic pressure introduced into the valve chamber 42 is equal to or higher than a predetermined value, the hydraulic pressure discharge passage 59A is opened, thereby preventing the pressure in the valve chamber 42 from exceeding the predetermined value. This protects the check valve 41, suppresses a decrease in the pump performance of the pump body 30, and further prevents the magnetic coupling from losing synchronization. The magnitude of the above-mentioned predetermined value, which is the valve opening pressure of the first check valve V1, is not particularly limited and can be set arbitrarily within a range in which the above-mentioned effects are obtained.

[0059] (Second check valve) The second check valve V2 is a valve device provided in the first hydraulic pressure introduction passage 58, and allows the flow of pump oil O from the valve chamber 42, the first hydraulic pressure introduction passage 58, and the second hydraulic pressure introduction passage 59 to the storage chamber 13 when the hydraulic pressures in the valve chamber 42, the first hydraulic pressure introduction passage 58, and the second hydraulic pressure introduction passage 59 are less than the above-mentioned predetermined value.

[0060] The second check valve V2 has a passage 58A that communicates between the first hydraulic pressure introduction passage 58 and the storage chamber 13 (see Figs. 3 and 5). The passage 58A is configured to be blocked when the second check valve V2 is open and to be opened when the second check valve V2 is closed. The second check valve V2 is set to a valve opening pressure that is smaller than the valve opening pressure of the first check valve V1.

[0061] In this way, the second check valve V2 performs the function of introducing the hydraulic pressure generated in the hydraulic pump 51 into the valve chamber 42 by opening the first hydraulic pressure introduction passage 58 and closing the passage portion 58A when the hydraulic pressure in the valve chamber 42, the first hydraulic pressure introduction passage 58, and the second hydraulic pressure introduction passage 59 is equal to or higher than a predetermined value (see FIG. 3), and performs the function of releasing the hydraulic pressure in the valve chamber 42 to the storage chamber 13 by blocking the first hydraulic pressure introduction passage 58 and opening the passage portion 58A when the hydraulic pressure in the valve chamber 42, the first hydraulic pressure introduction passage 58, and the second hydraulic pressure introduction passage 59 is less than a predetermined value (see FIG. 5).

[0062] (Third check valve) The third check valve V3 is provided in the lubricating oil flow path (oil supply flow path) 57, and is a valve device that controls the flow of the pump oil O in the forward direction from the reservoir chamber 13 side to the first pump chamber 311 and the second pump chamber 321 side. The third check valve V3 closes when the oil rotary vacuum pump 1 is stopped, and serves to prevent the pump oil O from flowing back from the first pump chamber 311 and the second pump chamber 321 to the reservoir chamber 13 side (see FIG. 5).

[0063] (Auxiliary flow path) The hydraulic pressure generating section 50 further has an auxiliary flow passage 59B provided between the second hydraulic pressure introduction flow passage 59 and the reservoir chamber 13. The auxiliary flow passage 59B is a flow passage that bypasses the hydraulic pressure discharge flow passage 59A, and is provided between the second hydraulic pressure introduction flow passage 59 and the hydraulic pressure discharge flow passage 59A in this embodiment (see FIG. 3). The auxiliary flow passage 59B includes a throttle passage 591.

[0064] When the oil rotary vacuum pump 1 stops operating, the first check valve V1 and the second check valve V2 close, and hydraulic pressure equal to or higher than a predetermined value in the valve chamber 42, the first hydraulic pressure introduction passage 58, and the second hydraulic pressure introduction passage 59 is released mainly through the passage 58A of the second check valve V2 to the reservoir chamber 13. However, immediately after the oil rotary vacuum pump 1 stops operating, hydraulic pressure is released from the first check valve V1, the hydraulic pump 51, the inside of the first pump chamber 311, and the inside of the second pump chamber 321 until the passage 58A is opened, but it takes time for the hydraulic pressure to reach a level at which the passage 58A of the second check valve V2 is opened, and the check valve 41 cannot be quickly moved to the valve closed position (FIG. 4(B)).

[0065] Therefore, in this embodiment, by providing an auxiliary flow path 59B that bypasses the hydraulic pressure discharge flow path 59A, the hydraulic pressure in the valve chamber 42 and the hydraulic pressure introduction flow paths 58, 59 is released to the storage chamber 13 via the auxiliary flow path 59B until the passage portion 58A is opened. This shortens the time it takes for the passage portion 58A to be opened, so that the check valve 41 can be quickly moved to the closed position and the check mechanism 40 can be made to function early.

[0066] According to an experiment conducted by the present inventor, the time from when the operation of the oil rotary vacuum pump 1 during operation was stopped until the check valve 41 was in the closed state was measured. As a result, it was confirmed that while the time was about 30 seconds in the absence of the auxiliary flow path 59B, the time was significantly reduced to about 2 seconds in the present embodiment having the auxiliary flow path 59B.

[0067] Although the flow path diameter of the throttle passage 591 is not particularly limited, if the flow path diameter of the throttle passage 591 is too large, the time until the passage portion 58 opens immediately after the operation of the oil rotary vacuum pump 1 is stopped is shortened, but the amount of pump oil supplied from the hydraulic pump 51 must be increased in order to introduce into the valve chamber 42 the hydraulic pressure required to maintain the check valve 41 in an open state during operation of the pump 1. For this reason, the flow path diameter of the throttle passage 591 is preferably adjusted according to the capacity of the hydraulic pump 51, the flow path length of the hydraulic pressure introduction flow paths 58, 59, the spring force of the biasing member 45, the valve opening pressure of the check valves V1, V2, etc., and is set so as to limit the flow rate of the pump oil O discharged from the second hydraulic pressure introduction flow path 59 to the hydraulic pressure discharge flow path 59A within a range in which a hydraulic pressure sufficient to maintain the check valve 41 in an open state (FIG. 4(A)) during operation of the oil rotary vacuum pump 1 can be secured in the valve chamber 42.

[0068] The auxiliary flow passage 59B may include an expansion chamber 592. The throttle passage 591 is provided between the expansion chamber 592 and the hydraulic pressure discharge flow passage 59A. The expansion chamber 592 functions as a buffer (accumulator), but may be omitted as necessary.

[0069] Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and various modifications can be made, as a matter of course.

[0070] For example, in the above embodiment, a two-stage oil rotary vacuum pump has been described as an example, but the present invention is not limited to this and can also be applied to a one-stage oil rotary vacuum pump. [Explanation of symbols]

[0071] 1...Oil rotary vacuum pump 10…Casing 13...Storage chamber 20...Drive unit 21...Rotation axis 30…Pump body 311,321…Pump room 321, 322...Rotor (rotating body) 40...Backflow prevention mechanism 41...Check valve 42…Valve chamber 45... Urging member 50...Hydraulic pressure generating section 51...Hydraulic pump 58, 59...Hydraulic pressure introduction passage 59A…Hydraulic discharge passage 59B...Auxiliary flow path 60...Oil pressure detector 61...Pressure sensor 62...Oil pressure detection line 63…Judgment section V1: First check valve V2: Second check valve V3: Third check valve

Claims

1. a casing having an intake port, an exhaust port, and a storage chamber for storing lubricating oil; a pump body disposed within the casing and having a pump chamber including a rotor that transfers gas sucked through the intake port toward the exhaust port; a check valve provided between the intake port and the pump chamber, and a valve chamber supporting the check valve movably between a first position for opening the intake port and a second position for closing the intake port; a hydraulic pressure generating unit including a hydraulic pump that pumps the lubricating oil from the storage chamber to the pump chamber in cooperation with the driving of the rotor and supplies hydraulic pressure to the valve chamber for holding the check valve at the first position; a hydraulic pressure detection unit that detects hydraulic pressure in the valve chamber; An oil rotary vacuum pump comprising:

2. 2. The oil rotary vacuum pump according to claim 1, The hydraulic pressure generating unit has an oil supply passage that communicates between the storage chamber and the pump chamber, and a hydraulic pressure introduction passage that communicates between the storage chamber and the valve chamber, The hydraulic pressure detection unit includes a pressure sensor attached to the casing, and a pressure detection line connecting the hydraulic pressure introduction passage and the pressure sensor. Oil rotary vacuum pump.

3. 3. The oil rotary vacuum pump according to claim 2, The hydraulic pressure detection unit further includes a determination unit that determines a drive state of the pump body based on an output of the pressure sensor. Oil rotary vacuum pump.

4. 3. The oil rotary vacuum pump according to claim 2, The hydraulic pressure generating unit further includes a hydraulic pressure discharge flow path that connects the hydraulic pressure introduction flow path and the storage chamber, and a first check valve that is provided in the hydraulic pressure discharge flow path and directs the flow of the lubricating oil from the valve chamber side to the storage chamber side in a forward direction. The first check valve is a hydraulic pressure adjusting valve that opens when the hydraulic pressure in the valve chamber is equal to or higher than a predetermined value. Oil rotary vacuum pump.

5. 5. The oil rotary vacuum pump according to claim 4, The hydraulic pressure generating unit further has an auxiliary flow path that is provided between the hydraulic pressure introduction flow path and the storage chamber and bypasses the hydraulic pressure discharge flow path, The auxiliary flow passage includes a throttle passage having a flow passage cross-sectional area smaller than a flow passage cross-sectional area of ​​the first check valve when the first check valve is open. Oil rotary vacuum pump.

6. 5. The oil rotary vacuum pump according to claim 4, The hydraulic pressure generating unit further includes a second check valve provided in the hydraulic pressure introduction passage and configured to allow the lubricating oil to flow from the valve chamber and the hydraulic pressure introduction passage to the reservoir chamber when the hydraulic pressure in the valve chamber and the hydraulic pressure introduction passage is less than the predetermined value. Oil rotary vacuum pump.

7. 7. The oil rotary vacuum pump according to claim 6, The hydraulic pressure generating unit further includes a third check valve that is provided in the oil supply passage and directs the flow of the lubricating oil from the reservoir chamber side to the pump chamber side in a forward direction. Oil rotary vacuum pump.

8. 2. The oil rotary vacuum pump according to claim 1, The check valve mechanism further includes a biasing member disposed in the valve chamber and biasing the check valve to the second position. Oil rotary vacuum pump.

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