Dry vacuum pump and dry vacuum pump system

Abstract

A dry vacuum pump (2) has formed therein a pump chamber (S1), a motor chamber (S2), and a gear chamber (S3), and comprises: a motor chamber connection port (2c) that connects the interior and exterior of the motor chamber (S2) so as to enable piping to be coupled to the exterior side; and a gear chamber connection port (2d) that connects the interior and exterior of the gear chamber (S3) so as to enable piping to be coupled to the exterior side. The dry vacuum pump is configured to be capable of evacuating the interior of the motor chamber (S2) and the interior of the gear chamber (S3) through the coupled piping by means of an external pump (3) connected to the motor chamber connection port (2c) and the gear chamber connection port (2d) via said piping. With this configuration, it is possible to perform gas replacement in a pump within a short period of time.

Description

Dry Vacuum Pumps and Dry Vacuum Pump Systems

[0001] The present invention relates to a dry vacuum pump and a dry vacuum pump system, and more particularly to a dry vacuum pump having an exhaust structure that enables gas replacement inside the pump to be performed in a short time, and a dry vacuum pump system that also includes peripheral equipment connected to the dry vacuum pump for gas replacement.

[0002] Dry vacuum pumps are used to circulate gases at semiconductor device manufacturing sites, etc. For example, Patent Document 1 describes that it is preferable to use a dry vacuum pump as an oil-free pump to circulate gases in a reaction chamber when processing wafers in a semiconductor manufacturing method (see paragraph 0022 of Patent Document 1).

[0003] Here, the dry vacuum pump includes a pump chamber that houses a rotor for transporting gas, a motor chamber that houses a motor for applying rotational power to the rotor, and a gear chamber that houses gears for rotating the pair of rotors in opposite directions. The motor chamber and the gear chamber are adjacent to the pump chamber and isolated from the pump chamber by a seal member. To use such a dry vacuum pump to circulate high-purity gas, such as in semiconductor device manufacturing sites, it is necessary to evacuate the entire pump and replace the air with the circulating gas.

[0004] Japanese Patent Application Laid-Open No. 2000-068212

[0005] However, in conventional pumps, when replacing the gas inside the entire pump with a circulating gas, the motor chamber and gear chamber are evacuated by drawing a vacuum through a pump chamber exhaust pipe connected to the pump chamber's intake and exhaust ports. That is, because the motor chamber and gear chamber are isolated from the pump chamber by a seal member, the motor chamber and gear chamber are evacuated through the pump chamber through a small gap in the seal member. As a result, it takes time to evacuate the entire pump, and it takes time to replace the gas inside the pump.

[0006] In view of the above, an object of the present invention is to provide a dry vacuum pump having an exhaust structure that enables gas replacement inside the pump to be performed in a short time, and to provide a dry vacuum pump system for such a dry vacuum pump that enables gas replacement in a short time.

[0007] In order to solve the above problems, the dry vacuum pump of the present invention comprises a pump chamber, a motor chamber, and a gear chamber, which are arranged adjacent to each other but isolated from each other by sealing members and each surrounded by walls to define an internal space, the pump chamber accommodating a pair of rotors for transporting gas, the motor chamber accommodating a motor for applying rotational power to the rotors, and the gear chamber accommodating gears for rotating the pair of rotors in mutually opposite directions in an interlocking manner, the dry vacuum pump comprising: a motor chamber connection port which connects the inside of the motor chamber to the outside and allows piping to be connected to the outside, and a gear chamber connection port which connects the inside of the gear chamber to the outside and allows piping to be connected to the outside, and the interiors of the motor chamber and the gear chamber can be evacuated by an external pump via the piping connected to the motor chamber connection port and the gear chamber connection port.

[0008] This dry vacuum pump further includes a motor chamber connecting pipe, which is a pipe connected to the motor chamber connecting port, a gear chamber connecting pipe, which is a pipe connected to the gear chamber connecting port, a motor chamber / gear chamber junction that connects the motor chamber connecting pipe and the gear chamber connecting pipe, and a motor chamber / gear chamber exhaust pipe, which is a pipe drawn out from the motor chamber / gear chamber junction to exhaust air from the motor chamber and the gear chamber.

[0009] In addition, in this dry vacuum pump, an orifice is arranged midway in the gear chamber connecting pipe to narrow the flow passage area and adjust the gas flow rate.

[0010] In addition, in this dry vacuum pump, an on-off valve capable of shutting off the flow of gas is disposed midway in the piping between the motor chamber connection port and the gear chamber connection port.

[0011] This dry vacuum pump also includes a cover in the gear chamber that extends from the wall on the pump chamber side to the vicinity of the gear chamber connection port and covers the outer periphery of the gear.

[0012] This cover covers at least the outer periphery of the gear from the top of the gear to the side in the direction in which the cutting edge of the gear rises.

[0013] A dry vacuum pump system according to the present invention comprises: a dry vacuum pump having a pump inlet and a pump outlet communicating with an internal space for compressing and transferring gas, the dry vacuum pump having a pump inlet and a pump outlet that transfers the gas while compressing it in the internal space and then discharging it from the pump outlet; an external pump that is appropriately connected via piping to at least either the pump inlet or the pump outlet to evacuate the inside of the dry vacuum pump; and a gas storage container that stores gas to be supplied into the dry vacuum pump and is appropriately connected via piping to at least either the pump inlet or the pump outlet, wherein the dry vacuum pump according to any one of claims 1 to 6 is used as the dry vacuum pump, and a motor chamber connecting pipe and a gear chamber connecting pipe are appropriately connected to the piping that appropriately connects at least either the pump inlet or the pump outlet to the external pump and the gas storage container, so that the motor chamber and the gear chamber can be evacuated by the external pump via the motor chamber connecting pipe or the gear chamber connecting pipe, and gas stored in the gas storage container can be supplied to the motor chamber and the gear chamber via the motor chamber connecting pipe or the gear chamber connecting pipe.

[0014] According to the present invention, it is possible to provide a dry vacuum pump having an exhaust structure that allows gas replacement inside the pump to be performed in a short time, and also to provide a dry vacuum pump system that allows gas replacement in a short time for such a dry vacuum pump.

[0015] 1 is a block diagram showing a configuration of a dry vacuum pump system according to an embodiment of the present invention; 2 is a flowchart showing a gas replacement procedure in the dry vacuum pump system according to an embodiment of the present invention;

[0016] Fig. 1 is a block diagram showing the configuration of a dry vacuum pump system 1 according to an embodiment. The dry vacuum pump system 1 according to an embodiment of the present invention will be described below with reference to the drawings. Note that Fig. 1 does not necessarily accurately reflect the entire actual configuration. Furthermore, in this specification, a gas having a specified component is referred to as a "gas" rather than a "vapor," but this is not intended to be limited to a gas having a specified component.

[0017] (Overall Configuration of Dry Vacuum Pump System 1) As shown in FIG. 1, the dry vacuum pump system 1 has a pump suction port 2a and a pump discharge port 2b that communicate with an internal space (pump chamber S1) for compressing and transferring gas, and is equipped with a dry vacuum pump 2 that transfers gas sucked in from the pump suction port 2a while compressing it in the internal space (pump chamber S1) and discharges it from the pump discharge port 2b.

[0018] Here, the dry vacuum pump 2 is operated to circulate high-purity gas within a vacuum system VS, primarily at semiconductor device manufacturing sites and the like (hereinafter referred to as "normal operation"). When operating the dry vacuum pump 2 normally, it is first necessary to replace the entire interior of the pump with the gas to be circulated (hereinafter referred to as "gas replacement"). Gas replacement is performed by drawing a vacuum to exhaust the gas contained within the entire interior of the dry vacuum pump 2, and then supplying the gas to be circulated. In FIG. 1, the pipes that are disconnected or not connected during normal operation and that are connected or connected during gas replacement are indicated by dashed dotted lines.

[0019] The dry vacuum pump system 1 is a system that is also capable of such gas replacement, and further comprises an external pump 3, which is a suction pump for drawing a vacuum inside the dry vacuum pump 2 and is appropriately connected via piping to the pump suction port 2a and the pump exhaust port 2b, and a gas storage container 4, which is a gas cylinder that contains gas to be supplied into the dry vacuum pump 2 and is appropriately connected via piping to the pump suction port 2a and the pump exhaust port 2b. The dry vacuum pump 2 will be further described.

[0020] (Configuration of Dry Vacuum Pump 2) As shown in FIG. 1 , the dry vacuum pump 2 is formed with a pump chamber S1, a motor chamber S2, and a gear chamber S3, which are adjacent to each other but separated by sealing members and surrounded by walls to define an internal space. The motor chamber S2 and the gear chamber S3 are located on either side of the pump chamber S1, sandwiching the pump chamber S1. The pump chamber S1 houses a pair of rotors R for transporting gas. The motor chamber S2 houses a motor M for applying rotational power to the rotors R. The gear chamber S3 houses a gear G for interlockingly rotating the pair of rotors R in opposite directions. In the dry vacuum pump 2, the pair of rotors R, which are connected by the gear G to rotate in opposite directions, are rotated by the power of the motor M. As described above, the dry vacuum pump 2 also has a pump suction port 2a and a pump discharge port 2b that communicate the inside of the pump chamber S1 with the outside. As a result, during normal operation, the dry vacuum pump 2 can transfer gas drawn into the pump chamber intake pipe L1 connected to the pump intake port 2a while compressing it by rotating the pair of rotors R, and discharge it through the pump chamber exhaust pipe L2 connected to the pump exhaust port 2b. Although not particularly limited, the dry vacuum pump 2 has pairs of rotors R arranged in multiple stages, and transfers the gas drawn into the pump intake port 2a toward the pump exhaust port 2b while increasing the degree of compression through the first stage pair of rotors R, the second stage pair of rotors R, the third stage, and so on. Because the dry vacuum pump 2 has each internal space isolated by a sealing member, even if water or oil is used in internal spaces other than the pump chamber S1, the water or oil will not diffuse into or backflow into the pump chamber S1, making it a vacuum pump that can obtain a clean vacuum.

[0021] When performing gas replacement, if an external pump 3 (described later) is connected to the pump intake port 2a and the pump exhaust port 2b via piping, the external pump 3 can evacuate the pump chamber S1 through the connected piping. If a gas storage container 4 (described later) is connected to the pump intake port 2a and the pump exhaust port 2b via piping while the pump chamber S1 is depressurized, the gas in the gas storage container 4 can be supplied to the pump chamber S1 through the connected piping.

[0022] The dry vacuum pump 2 further includes a motor chamber connection port 2c that connects the motor chamber S2 to the outside and allows piping to be connected to the outside, and a gear chamber connection port 2d that connects the gear chamber S3 to the outside and allows piping to be connected to the outside. By connecting an external pump 3 (described below) to the motor chamber connection port 2c and the gear chamber connection port 2d via piping, the dry vacuum pump 2 can directly evacuate the motor chamber S2 and the gear chamber S3 through the connected piping without using the pump chamber S1. Furthermore, by connecting a gas storage container 4 (described below) to the motor chamber connection port 2c and the gear chamber connection port 2d via piping while the motor chamber S2 and the gear chamber S3 are depressurized, the dry vacuum pump 2 can supply gas from the gas storage container 4 to the motor chamber S2 and the gear chamber S3 directly through the connected piping without using the pump chamber S1.

[0023] The dry vacuum pump 2 also uses oil in the gear chamber S3 to lubricate the gear G. In order to prevent oil from scattering from the gear G and flowing out of the gear chamber connection port 2d, the dry vacuum pump 2 has the gear chamber connection port 2d provided on the upper side of the gear chamber S3, and is also provided with a cover 2e in the gear chamber S3 that extends from the wall surface on the pump chamber S1 side to the vicinity of the gear chamber connection port 2d and covers the outer periphery of the gear G. This cover 2e covers at least the outer periphery of the gear G from the top of the gear G to the side in the direction in which the cutting edge of the gear G rises.

[0024] (Piping Configuration of Dry Vacuum Pump System 1) Next, the piping connections for performing gas replacement in the dry vacuum pump system 1 will be described. As shown in FIG. 1 , the dry vacuum pump system 1 includes a pump chamber intake pipe L1, a pump chamber exhaust pipe L2, a motor chamber connecting pipe L3, a gear chamber connecting pipe L4, a motor chamber / gear chamber exhaust pipe L5, a first route connecting pipe L6 (inlet-side first route connecting pipe L6A and outlet-side first route connecting pipe L6B), a second route connecting pipe L7, an external device connecting pipe L8, an external pump connecting pipe L9, and a gas storage container connecting pipe L10. These pipes have flow paths formed therein, and when performing gas replacement, they interconnect the dry vacuum pump 2, the external pump 3, and the gas storage container 4. Valves and the like for controlling the flow of gas flowing through the pipes are appropriately arranged along the pipes. An example of a piping configuration for carrying out specific gas replacement will be described in detail below, divided into a piping configuration connected to the dry vacuum pump 2 side and a piping configuration connected to the external pump 3 and gas storage container 4 side (external equipment side).

[0025] First, the piping configuration connected to the dry vacuum pump 2 will be described. A pump chamber intake pipe L1 is connected to the pump intake port 2a of the dry vacuum pump 2, and the tip of the pump chamber intake pipe L1 forms an intake-side first route replacement connection 11A, which serves as a connection part of the first route (intake side) connecting the pump chamber S1 to the external device side during gas replacement. A pump chamber exhaust pipe L2 is connected to the pump exhaust port 2b of the dry vacuum pump 2, and the tip of the pump chamber exhaust pipe L2 forms an exhaust-side first route replacement connection 11B, which serves as a connection part of the first route (exhaust side) connecting the pump chamber S1 to the external device side during gas replacement. This allows the dry vacuum pump 2 to connect the first route replacement connection 11 (11A, 11B) to the external device side during gas replacement, thereby enabling direct gas replacement of the pump chamber S1 by the external device.

[0026] The pump chamber intake pipe L1 branches at an intake pipe branching section 21 into a normal operation branch intake pipe L1', which is a separate flow path from the flow path leading to the external equipment side, and the tip of the normal operation branch intake pipe L1' is connected to the vacuum system VS. Similarly, the pump chamber exhaust pipe L2 branches at an exhaust pipe branching section 22 into a normal operation branch exhaust pipe L2', which is a separate flow path from the flow path leading to the external equipment side, and the tip of the normal operation branch exhaust pipe L2' is connected to the vacuum system VS. A first on-off valve V1 and a second on-off valve V2 are installed in the flow path leading to the external equipment side branching from the pump chamber intake pipe L1 at the intake pipe branching section 21 and the flow path of the normal operation branch intake pipe L1', respectively. Furthermore, a third on-off valve V3 and a fourth on-off valve V4 are installed in the flow path leading to the external equipment side branching from the pump chamber exhaust pipe L2 at the exhaust pipe branching section 22 and the flow path of the normal operation branch exhaust pipe L2', respectively. As a result, in the dry vacuum pump system 1, during normal operation, the first on-off valve V1 and the third on-off valve V3 are closed and the second on-off valve V2 and the fourth on-off valve V4 are opened, thereby connecting the pump chamber S1 of the dry vacuum pump 2 to the vacuum system VS and circulating gas in the vacuum system VS. During replacement operation, the first on-off valve V1 and the third on-off valve V3 are opened and the second on-off valve V2 and the fourth on-off valve V4 are closed, thereby connecting the pump chamber S1 of the dry vacuum pump 2 to an external device and replacing the gas in the pump chamber S1.

[0027] The motor chamber connection port 2c of the dry vacuum pump 2 is connected to the motor chamber connection pipe L3, and the gear chamber connection port 2d is connected to the gear chamber connection pipe L4. The ends of the motor chamber connection pipe L3 and the gear chamber connection pipe L4 are connected at a motor chamber-gear chamber junction 23. An orifice 13 is disposed midway along the gear chamber connection pipe L4 to narrow the flow path area and adjust the gas flow rate. This orifice 13 is provided to prevent the gear chamber S3 from suddenly depressurizing, causing the oil inside to boil and foam, which may then enter the gear chamber connection pipe L4. Its specifications are appropriately selected taking into consideration the amount of oil in the gear chamber S3, the evacuation time during use, and other factors. Furthermore, a fifth on-off valve V5 capable of shutting off the gas flow is disposed midway along the gear chamber connection pipe L4 between the orifice 13 and the motor chamber-gear chamber junction 23. As a result, the gear chamber connecting pipe L4 consists of a first gear chamber connecting pipe portion L4a on the gear chamber S3 side relative to the orifice 13, a second gear chamber connecting pipe portion L4b between the orifice 13 and the fifth opening / closing valve V5, and a third gear chamber connecting pipe portion L4c between the fifth opening / closing valve V5 and the motor chamber / gear chamber junction 23.

[0028] A motor chamber / gear chamber exhaust pipe L5 is drawn out from the motor chamber / gear chamber junction 23, and the tip of the motor chamber / gear chamber exhaust pipe L5 forms a second route substitution connection part 12 which serves as a junction exhaust port for the motor chamber S2 and the gear chamber S3.

[0029] Next, a description will be given of the piping configuration connected to the external pump 3 and the gas storage container 4. When performing gas replacement, the suction port side first route connecting pipe L6A is connected to the suction port side first route replacement connecting part 11A, the outlet side first route connecting pipe L6B is connected to the outlet side first route replacement connecting part 11B, and the second route connecting pipe L7 is connected to the second route replacement connecting part 12. An end of the suction port side first route connecting pipe L6A and an end of the outlet side first route connecting pipe L6B are connected at a first route junction 24, and an end of the first route connecting pipe L6 and an end of the second route connecting pipe L7 are connected at a second route junction 25.

[0030] An external equipment connecting pipe L8 is drawn out from the second route junction 25 and extends to the external equipment branching part 26. A sixth on-off valve V6 capable of blocking the flow of gas is disposed midway along the external equipment connecting pipe L8. As a result, the external equipment connecting pipe L8 is made up of a first external equipment connecting pipe portion L8a between the second route junction 25 and the sixth on-off valve V6, and a second external equipment connecting pipe portion L8b between the sixth on-off valve V6 and the external equipment branching part 26.

[0031] An external pump connecting pipe L9 extends from the external equipment branching section 26. The external pump 3 is connected to one end of the external pump connecting pipe L9. A seventh on-off valve V7 capable of blocking the flow of gas is disposed midway along the external pump connecting pipe L9. As a result, the external pump connecting pipe L9 is made up of a first external pump connecting pipe section L9a between the external equipment branching section 26 and the seventh on-off valve V7, and a second external pump connecting pipe section L9b between the seventh on-off valve V7 and the external pump 3.

[0032] Furthermore, a gas storage container connecting pipe L10 is drawn out from the external equipment branching portion 26 separately from the external pump connecting pipe L9. The gas storage container 4 is connected to an end of the gas storage container connecting pipe L10. An eighth on-off valve V8 capable of blocking the flow of gas is disposed midway along the gas storage container connecting pipe L10. As a result, the gas storage container connecting pipe L10 is made up of a first gas storage container connecting pipe portion L10a between the external equipment branching portion 26 and the eighth on-off valve V8, and a second gas storage container connecting pipe portion L10b between the eighth on-off valve V8 and the gas storage container 4.

[0033] In the dry vacuum pump system 1 having such a piping configuration, when the first on-off valve V1, the third on-off valve V3, the fifth on-off valve V5, the sixth on-off valve V6, and the seventh on-off valve V7 are opened and the second on-off valve V2, the fourth on-off valve V4, and the eighth on-off valve V8 are closed, the pump chamber S1 and the external pump 3 are communicated via the pump suction port 2a, the pump chamber intake pipe L1, the suction port side first route connecting pipe L6A, the external equipment connecting pipe L8, and the external pump connecting pipe L9, and also via the pump discharge port 2b, the pump chamber exhaust pipe L2, the discharge port side first route connecting pipe L6B, the external equipment connecting pipe L8, and the external pump connecting pipe L9. At the same time, the motor chamber S2 and the external pump 3 are communicated via the motor chamber connection port 2c, the motor chamber connecting pipe L3, the motor chamber / gear chamber exhaust pipe L5, the second route connecting pipe L7, the external equipment connecting pipe L8, and the external pump connecting pipe L9. At the same time, the gear chamber S3 and the external pump 3 are communicated via the gear chamber connection port 2d, the gear chamber connecting pipe L4, the motor chamber / gear chamber exhaust pipe L5, the second route connecting pipe L7, the external equipment connecting pipe L8, and the external pump connecting pipe L9. In other words, when the external pump 3 is driven in this state, the pump chamber S1, the motor chamber S2, and the gear chamber S3 of the dry vacuum pump 2 are directly evacuated by the external pump 3 along the route indicated by the dashed line D1 in FIG. 1 .

[0034] Furthermore, in the dry vacuum pump system 1 having such a piping configuration, when the first on-off valve V1, the third on-off valve V3, the fifth on-off valve V5, the sixth on-off valve V6, and the eighth on-off valve V8 are opened and the second on-off valve V2, the fourth on-off valve V4, and the seventh on-off valve V7 are closed, the pump chamber S1 and the gas storage container 4 are communicated with each other via the pump suction port 2a, the pump chamber intake pipe L1, the suction port side first route connecting pipe L6A, the external equipment connecting pipe L8, and the gas storage container connecting pipe L10, and also via the pump exhaust port 2b, the pump chamber exhaust pipe L2, the exhaust port side first route connecting pipe L6B, the external equipment connecting pipe L8, and the gas storage container connecting pipe L10. 1 , the motor chamber S2 and the gas storage container 4 are communicated with each other via the motor chamber connection port 2c, the motor chamber connecting pipe L3, the motor chamber / gear chamber exhaust pipe L5, the second route connecting pipe L7, the external equipment connecting pipe L8, and the gas storage container connecting pipe L10. The gear chamber S3 and the gas storage container 4 are communicated with each other via the gear chamber connection port 2d, the gear chamber connecting pipe L4, the motor chamber / gear chamber exhaust pipe L5, the second route connecting pipe L7, the external equipment connecting pipe L8, and the gas storage container connecting pipe L10. In other words, when the eighth on-off valve V8 is opened and the seventh on-off valve V7 is closed while the dry vacuum pump 2 is depressurized, the gas in the gas storage container 4 is supplied to the pump chamber S1, the motor chamber S2, and the gear chamber S3 of the dry vacuum pump 2 via the route indicated by the dashed line D2 in FIG.

[0035] In the dry vacuum pump system 1 having such a piping configuration, as described above, the on-off valves are switched so that the pump chamber S1, motor chamber S2, and gear chamber S3 of the dry vacuum pump 2 are directly evacuated by the external pump 3, and the dry vacuum pump 2 is brought into a depressurized state. After that, the seventh on-off valve V7 and the eighth on-off valve V8 are switched so that the gas in the gas storage container 4 is supplied into the dry vacuum pump 2, thereby performing gas replacement.

[0036] During normal operation, the dry vacuum pump 2 compresses gas toward the gear chamber S3, which tends to increase the pressure in the gear chamber S3, located on the compression side of the pump chamber S1, compared to the pressure in the motor chamber S2, located on the opposite side. When the fifth on-off valve V5 is not closed, the motor chamber S2 and the gear chamber S3 communicate with each other via the motor chamber connection port 2c, the motor chamber connection pipe L3, the gear chamber connection pipe L4, and the gear chamber connection port 2d. When the motor chamber S2 and the gear chamber S3 are connected, the pressure difference between the motor chamber S2 and the gear chamber S3 causes gas to move, potentially causing oil mist in the gear chamber S3 to enter the motor chamber S2 via the piping. For this reason, the dry vacuum pump system 1 is provided with the fifth on-off valve V5 to block the airflow between the motor chamber S2 and the gear chamber S3 during normal operation, thereby maintaining a cleaner environment within the dry vacuum pump 2.

[0037] In the above description of the configuration, the piping configuration is described separately from the configuration of the dry vacuum pump 2, but the piping of the motor chamber connecting pipe L3, the gear chamber connecting pipe L4, and the motor chamber / gear chamber exhaust pipe L5 are connected to the dry vacuum pump 2 even during normal operation, and may be circulated separately from the dry vacuum pump 2 as piping of the dry vacuum pump system 1, or may be circulated integrally as a component of the dry vacuum pump 2. Similarly, the pump chamber exhaust pipe L2 may be circulated separately from the dry vacuum pump 2 as piping of the dry vacuum pump system 1, or may be circulated integrally as a component of the dry vacuum pump 2.

[0038] (Gas Replacement by Dry Vacuum Pump System 1) Fig. 2 is a flowchart showing a gas replacement procedure in the embodiment of the dry vacuum pump system 1. In the dry vacuum pump system 1, before normal operation, as shown in Fig. 2, gas replacement is performed through a replacement preparation step ST1, a vacuuming step ST2, and a gas supply step ST3.

[0039] First, in the replacement preparation step ST1, the first route connecting pipe L6 is connected to the first route replacement joint 11, and the second route connecting pipe L7 is connected to the second route replacement joint 12, resulting in the piping state shown in Fig. 1 (a state in which the piping indicated by the dashed dotted lines is also connected). At this stage, it is preferable to close at least the sixth opening / closing valve V6 and the eighth opening / closing valve V8.

[0040] Next, in the evacuation step ST2, the fifth on-off valve V5, the sixth on-off valve V6, and the seventh on-off valve V7 are opened, and the eighth on-off valve V8 is closed, and the external pump 3 is operated. As described above, the external pump 3 directly evacuates the pump chamber S1 of the dry vacuum pump 2 via the first route (both the first route on the suction port side and the first route on the outlet side) through the suction port 2a and the outlet port 2b, and the motor chamber S2 and the gear chamber S3 via the second route (the second route) through the pump chamber exhaust pipe L2, the motor chamber connecting pipe L3, and the gear chamber connecting pipe L4, thereby reducing the pressure in each chamber. Note that the openings of the fifth on-off valve V5, the sixth on-off valve V6, and the seventh on-off valve V7, the timings at which each on-off valve is opened, and the timing at which the external pump is operated are not limited to the above order and may be changed or adjusted as appropriate to prevent a sudden reduction in the pressure in each chamber.

[0041] Next, in the gas supply step ST3, the fifth on-off valve V5, the sixth on-off valve V6, and the eighth on-off valve V8 are switched to an open state, and the seventh on-off valve V7 is switched to a closed state, so that the gas in the gas storage container 4 is supplied to the pump chamber S1, the motor chamber S2, and the gear chamber S3, which have been evacuated in the evacuation step ST2, from the pump chamber exhaust pipe L2, the motor chamber connecting pipe L3, and the gear chamber connecting pipe L4, respectively.

[0042] This completes the gas replacement in the dry vacuum pump system 1. After the gas replacement is completed, the first on-off valve V1 and the third on-off valve V3 are closed, and the second on-off valve V2 and the fourth on-off valve V4 are opened to switch to a circulation route that circulates gas within the vacuum system VS, and the dry vacuum pump 2 can be operated normally.

[0043] (Operations and Effects) The dry vacuum pump 2 of this embodiment includes a motor chamber connection port 2c that connects the motor chamber S2 to the outside and allows piping to be connected to the outside, and a gear chamber connection port 2d that connects the gear chamber S3 to the outside and allows piping to be connected to the outside, and is configured so that the motor chamber S2 and the gear chamber S3 can be evacuated by the external pump 3 via the piping connected to the motor chamber connection port 2c and the gear chamber connection port 2d. In other words, the dry vacuum pump 2 can evacuate the motor chamber S2 and the gear chamber S3 directly without using the pump chamber S1, thereby shortening the evacuation time during gas replacement. Therefore, the dry vacuum pump 2 has an evacuation structure that allows gas replacement inside the pump to be performed in a short time.

[0044] The dry vacuum pump 2 further includes a cover 2e in the gear chamber S3 that extends from the wall on the pump chamber S1 side to the vicinity of the gear chamber connection port 2d and covers the outer periphery of the gear G. This cover 2e covers the outer periphery of the gear G at least from the top of the gear G toward the direction in which the cutting edge of the gear G rises. This makes it difficult for oil in the gear chamber S3 to scatter and flow out of the gear chamber connection port 2d, and therefore a cleaner environment can be maintained.

[0045] The dry vacuum pump system 1 or the dry vacuum pump 2 further includes a motor chamber connecting pipe L3 that is a pipe connected to the motor chamber connecting port 2c, a gear chamber connecting pipe L4 that is a pipe connected to the gear chamber connecting port 2d, a motor chamber / gear chamber junction 23 that connects the motor chamber connecting pipe L3 and the gear chamber connecting pipe L4, and a motor chamber / gear chamber exhaust pipe L5 that is a pipe drawn out from the motor chamber / gear chamber junction 23. Therefore, with the dry vacuum pump system 1 or the dry vacuum pump 2, the motor chamber S2 and the gear chamber S3 can be evacuated with a single external pump 3 during gas replacement, making it possible to perform gas replacement in a compact, low-cost manner and in a short time.

[0046] Furthermore, in the dry vacuum pump system 1 or the dry vacuum pump 2, an orifice 13 that narrows the flow path area and adjusts the gas flow rate is arranged midway through the gear chamber connecting pipe L4. Therefore, with the dry vacuum pump system 1 or the dry vacuum pump 2, it is possible to suppress the risk of the gear chamber S3 being suddenly depressurized, causing the oil inside to boil and foam, which may then enter the gear chamber connecting pipe L4.

[0047] Furthermore, in the dry vacuum pump system 1 or the dry vacuum pump 2, a fifth on-off valve V5 capable of blocking the flow of gas is disposed midway in the piping between the motor chamber connection port 2c and the gear chamber connection port 2d. Therefore, according to the dry vacuum pump system 1 or the dry vacuum pump 2, the airflow between the motor chamber S2 and the gear chamber S3 can be blocked by the fifth on-off valve V5, and therefore, during normal operation, it is possible to prevent oil mist in the gear chamber S3 from entering the motor chamber S2 due to the pressure difference between the motor chamber S2 and the gear chamber S3.

[0048] The dry vacuum pump system 1 also includes a dry vacuum pump 2 that provides the above-described effects. The dry vacuum pump system 1 also includes an external pump 3 that is appropriately connected via piping to the pump suction port 2a and the pump exhaust port 2b to evacuate the dry vacuum pump 2, and a gas storage container 4 that stores gas to be supplied to the dry vacuum pump 2 and is appropriately connected via piping to the pump suction port 2a and the pump exhaust port 2b. The dry vacuum pump system 1 is a system that combines the dry vacuum pump 2, which has an exhaust structure that can perform gas replacement within the pump in a short time, with the external pump 3 for exhausting the pump and the gas storage container 4 that can supply gas into the pump. Therefore, the above-described effects of the dry vacuum pump 2 enable gas replacement within the pump in a short time. Therefore, the dry vacuum pump system 1 is a dry vacuum pump system that can perform gas replacement with a dry vacuum pump in a short time.

[0049] Although the present invention has been described based on the above embodiment, the present invention is not limited to the above embodiment and can be embodied in various forms without departing from the spirit of the present invention, and for example, the following modifications are also possible.

[0050] (1) The positions, shapes and numbers of components, piping configurations, positions of valves, etc., operating procedures, etc. described in the above embodiments are examples and can be changed within the scope that does not impair the effects of the present invention.

[0051] (2) In the above embodiment, the fifth on-off valve V5 capable of blocking the gas flow between the motor chamber connection port 2c and the gear chamber connection port 2d is disposed between the orifice 13 in the gear chamber connection pipe L4 and the motor chamber-gear chamber junction 23. However, the present invention is not limited to this. The fifth on-off valve V5 may be disposed between the motor chamber connection port 2c and the gear chamber connection port 2d to prevent oil mist from inside the gear chamber S3 from entering the motor chamber S2. For example, the fifth on-off valve V5 may be disposed between the motor chamber connection port 2c and the motor chamber-gear chamber junction 23.

[0052] (3) In the above embodiment, an external device for gas replacement is connected to the pump suction port 2 a and the pump discharge port 2 b via piping, but the present invention is not limited to this. It is sufficient that at least one of the pump suction port 2 a and the pump discharge port 2 b is connected to an external device for gas replacement.

[0053] (4) In the above embodiment, the pump chamber S1, the motor chamber S2, and the gear chamber S3 are evacuated by a single external pump 3 by joining the pipes communicating with the respective internal spaces. However, the present invention is not limited to this. A plurality of external pumps may be provided corresponding to the internal spaces of the pump chamber S1, the motor chamber S2, and the gear chamber S3, respectively, and each internal space may be evacuated using the corresponding external pump.

[0054] (5) In the above embodiment, the piping connecting the first route replacement connection part 11 and the second route replacement connection part 12 is changed between during gas replacement and during normal operation. However, the present invention is not limited to this. For example, a piping configuration may be adopted in which a three-way valve or the like is used as a switching valve, and the route during gas replacement and the route during normal operation are always connected, and the communication route of the switching valve is switched.

[0055] (6) In the above-described embodiment, the dry vacuum pump 2 is connected to either the external pump 3 or the gas storage container 4 during gas replacement by switching the on-off valve. However, it is also preferable to electrically perform such switching so that it can be performed automatically.

Claims

1. A dry vacuum pump having a pump chamber, a motor chamber, and a gear chamber arranged adjacent to each other but isolated from each other by sealing members, each surrounded by walls to define an internal space, wherein the pump chamber houses a pair of rotors for transporting gas, the motor chamber houses a motor for applying rotational power to the rotors, and the gear chamber houses gears for rotating the pair of rotors in mutually opposite directions in an interlocking manner, the dry vacuum pump comprising: a motor chamber connection port that connects the inside of the motor chamber to the outside and allows piping to be connected to the outside, and a gear chamber connection port that connects the inside of the gear chamber to the outside and allows piping to be connected to the outside, wherein the motor chamber and the gear chamber can be evacuated by an external pump via the piping connected to the motor chamber connection port and the gear chamber connection port.

2. A dry vacuum pump according to claim 1, further comprising: a motor chamber connecting pipe which is a pipe connected to the motor chamber connecting port; a gear chamber connecting pipe which is a pipe connected to the gear chamber connecting port; a motor chamber-gear chamber junction which connects the motor chamber connecting pipe and the gear chamber connecting pipe; and a motor chamber-gear chamber exhaust pipe which is a pipe drawn out from the motor chamber-gear chamber junction to exhaust air from the motor chamber and the gear chamber.

3. A dry vacuum pump according to claim 2, wherein an orifice is disposed midway along the gear chamber connecting pipe to restrict the flow area and adjust the gas flow rate.

4. A dry vacuum pump according to claim 2, wherein an open / close valve capable of shutting off the flow of gas is disposed midway in the piping between the motor chamber connection port and the gear chamber connection port.

5. A dry vacuum pump according to claim 2, further comprising a cover within the gear chamber, the cover extending from the wall surface on the pump chamber side to the vicinity of the gear chamber connection port and covering the outer periphery of the gear.

6. A dry vacuum pump according to claim 5, wherein the cover covers at least the outer periphery of the gear from the top of the gear to the side in the direction in which the cutting edge of the gear rises.

7. A dry vacuum pump having a pump inlet and a pump outlet communicating with an internal space for compressing and transferring gas, which transfers gas taken in from the pump inlet while compressing it in the internal space and then discharges it from the pump outlet; an external pump which is appropriately connected via piping to at least one of the pump inlet and the pump outlet in order to evacuate the inside of the dry vacuum pump; and a gas storage container which stores gas to be supplied into the dry vacuum pump and which is appropriately connected via piping to at least one of the pump inlet and the pump outlet. a motor chamber connecting pipe and a gear chamber connecting pipe are appropriately connected to piping that appropriately connects at least one of the pump suction port and the pump discharge port to the external pump and the gas storage container, thereby enabling the motor chamber and the gear chamber to be evacuated by the external pump via the motor chamber connecting pipe or the gear chamber connecting pipe, and enabling gas stored in the gas storage container to be supplied to the motor chamber and the gear chamber via the motor chamber connecting pipe or the gear chamber connecting pipe.

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