Multistage type biaxial rotary pump and multistage type claw pump

Abstract

Provided are a multistage type biaxial rotary pump and a multistage type claw pump in which pump chambers and rotors provided in multiple stages can be efficiently cooled by air or water. The multistage type biaxial rotary pump has pump chambers provided in multiple stages, and comprises two rotary shafts 20A, 20B and two rotors 21A, 21B, 22A, 22B of each stage disposed inside pump chambers 11, 12 of each stage. A front-rear inter-stage section 30 is provided between a front-stage pump exhaust side end wall 11a where an exhaust port 11b of a front-stage pump chamber 11 is provided and a rear-stage pump intake side end wall 12a where an intake port 12b of a rear-stage pump chamber 12 is provided. The front-rear inter-stage section 30 comprises an inter-stage communication chamber 33 communicating the exhaust port 11b with the intake port 12b in the middle in the left-right direction, a one-side inter-stage liquid cooling passage 31 that allows cooling air or cooling liquid to flow from below to above on one side in the left-right direction, and an other-side inter-stage liquid cooling passage 32 that allows cooling air or cooling liquid to flow from below to above on the other side in the left-right direction.

Description

Multistage two-shaft rotary pump and multistage claw pump

[0001] The present invention relates to a multi-stage two-shaft rotary pump having multiple stages of pump chambers, each having a cross-sectional shape formed by overlapping parts of two circles in the left-right direction, two rotating shafts arranged parallel to each other in the pump chamber of each stage and rotated at the same speed in opposite directions by a pair of gears, and two rotors for each stage arranged in the pump chamber of each stage corresponding to the two rotating shafts and configured so that they can rotate without contacting each other and discharge the sucked gas.

[0002] A conventional rotary pump proposed by the present applicant is one in which a rotor that rotates in a pump chamber 10 is attached to one end of a rotating shaft and supported in a cantilevered state, and the pump body is divided so that a cooling gap is formed between a pump chamber body portion that is formed by a cylinder portion and end wall portions that are provided on each of both end faces of the cylinder portion to form the pump chamber, and a bearing portion body portion that is provided with a bearing portion that bears the rotating shaft so that the rotor is attached to one end of the rotating shaft and supported in a cantilevered state (see Patent Document 1).

[0003] According to this conventional rotary pump, the transmission of heat generated by driving to the body of the bearing portion is reduced by air cooling, thereby achieving the effect of extending the life of functional parts that make up the bearing portion and the like.

[0004] Furthermore, the present applicant has proposed a conventional double-shaft rotary pump and claw pump that includes a pump chamber body portion having a cylinder portion, one end wall portion, and the other end wall portion to form a pump chamber, two rotary shafts, two rotors that rotate without contacting each other, and a bearing body portion that constitutes a structural wall portion in which a bearing portion is provided and also constitutes a structural wall portion that serves as a gearbox, wherein the pump body is partitioned into a pump chamber body portion and a bearing body portion so that a cooling gap is formed between the pump chamber body portion and the bearing body portion, and a bearing coolant flow path is provided in the structural wall portion that is located on the pump chamber body portion side of the bearing body portion (see Patent Document 2).

[0005] According to the conventional biaxial rotary pump and claw pump, the overheating of the pump body can be more effectively prevented by using a coolant, and the reliability of the pump operation can be significantly improved.

[0006] JP 2021-67246 A (page 1, FIG. 2) JP 2023-13385 A (page 1, FIG. 1)

[0007] The problem to be solved with respect to multi-stage biaxial rotary pumps and multi-stage claw pumps is that, while for single-stage biaxial rotary pumps, configurations have been proposed in the aforementioned prior art documents to appropriately prevent the pump body from overheating by air or water cooling, no appropriate configuration has been proposed for multi-stage biaxial rotary pumps, which require high vacuum performance, etc. For example, in a single-stage biaxial rotary pump (single-stage water-cooled vacuum pump) such as that shown in the aforementioned Patent Document 2, it is effective to cool the exhaust port side (exhaust side) of the pump chamber in the rotor to prevent contact between the rotors, and in this single-stage water-cooled vacuum pump, efficient cooling is achieved by adding a water-cooling cooling circuit to the exhaust side, but there is a problem that the number of parts is increased and costs are high.

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a multi-stage two-shaft rotary pump and a multi-stage claw pump that can rationally prevent the rotor and the pump body from overheating by air or water cooling.

[0009] In order to achieve the above object, the present invention has the following configuration: In one aspect of the multistage two-shaft rotary pump according to the present invention, a multistage two-shaft rotary pump is provided with pump chambers each having a cross-sectional shape formed by overlapping parts of two circles in the left-right direction, two rotary shafts arranged in parallel in the pump chamber of each stage and rotated at the same speed in opposite directions by a pair of gears, and two rotors for each stage arranged in the pump chamber of each stage corresponding to the two rotary shafts and formed so as to rotate without contacting each other and to discharge sucked gas, and the multistage two-shaft rotary pump has an exhaust side end wall of a front-stage pump provided with an exhaust port of the front-stage pump chamber, and a rear-stage pump. In the front and rear interstage section provided between the intake side end walls of the rear-stage pumps where the intake ports of the pump chambers are provided, the system comprises: an interstage communication chamber provided midway between the two rotating shafts in the left-right direction as a passage that communicates between the exhaust port of the front-stage pump chamber and the intake port of the rear-stage pump chamber; a one-side interstage air-cooling flow path formed on one side of the two rotating shafts in the left-right direction as a flow path that allows cooling air to flow from the bottom to the top; and a other-side interstage air-cooling flow path formed on the other side of the two rotating shafts in the left-right direction as a flow path that allows cooling air to flow from the bottom to the top.

[0010] Furthermore, according to one aspect of the multi-stage two-shaft rotary pump of the present invention, the front and rear inter-stage section can include an exhaust-side end wall of the front-stage pump and an intake-side end wall of the rear-stage pump, and the front and rear inter-stage sections are integrally provided so as to form the inter-stage communication chamber, the one-side inter-stage air-cooling passage, and the other-side inter-stage air-cooling passage.

[0011] Furthermore, according to one embodiment of the multi-stage two-shaft rotary pump of the present invention, a cooling gap is provided between a pump chamber body portion in which the multi-stage pump chambers are provided and a bearing body portion in which bearings are provided that support the two rotary shafts on the side to which the driving force is transmitted, in a region corresponding to the periphery of the two rotary shafts, allowing cooling air to flow from the lower side to the upper side.

[0012] Furthermore, according to one aspect of the multi-stage two-shaft rotary pump of the present invention, a centrifugal blower fan is attached to a coupling provided for transmitting the driving force of a drive motor on one of the two rotary shafts, and a cooling air guide portion is provided for using the airflow generated by the centrifugal blower fan as cooling air and guiding the airflow through the one-side interstage air cooling flow passage, the other-side interstage air cooling flow passage, and the cooling gap between the body portion from below to above.

[0013] Furthermore, according to one aspect of the multi-stage claw pump of the present invention, of the one-side interstage air-cooling passage and the other-side interstage air-cooling passage, the one-side interstage air-cooling passage is provided closer to the exhaust port of the front-stage pump chamber that is eccentrically arranged as a claw pump.

[0014] According to one embodiment of the multistage two-shaft rotary pump of the present invention, a multistage two-shaft rotary pump is provided with pump chambers each having a cross-sectional shape obtained by overlapping parts of two circles in the left-right direction, two rotary shafts arranged in parallel in the pump chamber of each stage and rotated at the same speed in opposite directions by a pair of gears, and two rotors arranged in the pump chamber of each stage corresponding to the two rotary shafts and formed so as to be able to rotate without contacting each other and discharge the sucked gas, and the multistage two-shaft rotary pump has an exhaust side end wall of a front stage pump provided with an exhaust port of the front stage pump chamber, and an intake port of a rear stage pump chamber provided with an intake port of the rear stage pump chamber. In the front and rear interstage section provided between the intake side end walls of the rear-stage pumps, there are provided: an interstage communication chamber provided as a passageway communicating between the exhaust port of the front-stage pump chamber and the intake port of the rear-stage pump chamber, midway between the two rotating shafts in the left-right direction and passing vertically between the two rotating shafts; a one-side interstage liquid-cooling flow path formed on one side of the two rotating shafts in the left-right direction as a flow path through which coolant can flow from below to above; and a other-side interstage liquid-cooling flow path formed on the other side of the two rotating shafts in the left-right direction as a flow path through which coolant can flow from below to above.

[0015] Furthermore, according to one aspect of the multi-stage two-shaft rotary pump of the present invention, the upper side of the one-side interstage liquid-cooling flow passage and the lower side of the other-side interstage liquid-cooling flow passage are connected by a coolant communicating passage so that the coolant is introduced from the lower side of the one-side interstage liquid-cooling flow passage and discharged at the upper side, and subsequently introduced from the lower side of the other-side interstage liquid-cooling flow passage and discharged from the upper side.

[0016] Furthermore, according to one aspect of the multi-stage two-shaft rotary pump of the present invention, a bearing portion liquid-cooling flow passage is provided in the bearing portion so that the cooling liquid is introduced into the one-side inter-stage liquid-cooling flow passage after cooling the bearing portion that supports the two rotary shafts.

[0017] Furthermore, according to one aspect of the multi-stage two-shaft rotary pump of the present invention, the front and rear inter-stage section can include an exhaust-side end wall of the front-stage pump and an intake-side end wall of the rear-stage pump, and the front and rear inter-stage sections are integrally provided so as to form the inter-stage communication chamber, the one-side inter-stage liquid-cooled flow passage, and the other-side inter-stage liquid-cooled flow passage.

[0018] Furthermore, according to one aspect of the multi-stage two-shaft rotary pump of the present invention, the one-side interstage liquid-cooling flow passage and the other-side interstage liquid-cooling flow passage are provided as flow passages through which cooling liquid flows by having their upper and lower ends closed by upper and lower closing plates, respectively, and by removing the upper and lower closing plates, the one-side interstage air-cooling flow passage and the other-side interstage air-cooling flow passage through which cooling air flows can be formed.

[0019] Furthermore, according to one aspect of the multi-stage claw pump of the present invention, the multi-stage two-shaft rotary pump is a claw pump, and of the one-side interstage liquid-cooling flow passage and the other-side interstage liquid-cooling flow passage, the one-side interstage liquid-cooling flow passage is arranged as a side to which the coolant is introduced first, and is provided close to the exhaust port of the previous-stage pump chamber which is provided eccentrically as a claw pump.

[0020] The multi-stage two-shaft rotary pump and the multi-stage claw pump according to the present invention have the particularly advantageous effect of being able to rationally prevent the rotors and the pump body from overheating by air cooling or water cooling.

[0021] 1. A perspective view showing an example of a multistage two-shaft rotary pump (claw pump) with a water-cooling function according to the present invention. 1. An exploded view of the example of FIG. 1. 2. A side view of the example of FIG. 1. 3. A cross-sectional view of the example of FIG. 1 taken along line A-A in FIG. 3. 4. A cross-sectional view of the example of FIG. 1 taken along line B-B in FIG. 3. 5. A front view of the example of FIG. 1. 6. A plan view of the example of FIG. 1. 7. A rear view of the example of FIG. 1. 8. A perspective view showing an example of a multistage two-shaft rotary pump (claw pump) with an air-cooling function according to the present invention. 9. A plan view of the example of FIG. 9. 10. A cross-sectional view of the example of FIG. 9 taken along line A-A in FIG. 11. 12. A cross-sectional view of the example of FIG. 9 taken along line B-B in FIG. 11. 13. A front view of the example of FIG. 9. 14. A cross-sectional view showing an example in which a cooling air guide member is provided in the example of FIG. 9.

[0022] Two embodiments of a multistage two-shaft rotary pump (multistage claw pump) according to the present invention will now be described in detail with reference to the accompanying drawings (Figs. 1 to 15). (Figs. 1 to 8 show a water-cooled two-stage two-shaft rotary pump as a first embodiment, and Figs. 9 to 15 show an air-cooled two-stage two-shaft rotary pump as a second embodiment.) While these embodiments are water-cooled or air-cooled vacuum pumps, the present invention is not limited thereto and can also be used as a blower or gas compressor that uses exhaust gas as a product gas. Furthermore, it goes without saying that a cooling liquid other than water or a cooling gas other than air can be used as a cooling means.

[0023] First, a first embodiment will be described with reference to Figures 1 to 8. The multi-stage two-shaft rotary pump according to the present invention has a basic configuration (two-stage configuration in this embodiment) in which pump chambers 11, 12, each having a cross-sectional shape formed by overlapping portions of two circles in the left-right direction, are provided in multiple stages (two stages). Two rotating shafts 20A, 20B are arranged parallel to each other in the pump chambers 11, 12 of each stage and rotated at the same speed in opposite directions by a pair of gears (not shown). Two rotors 21A, 21B, 22A, 22B are arranged in each stage in correspondence with the two rotating shafts 20A, 20B in the pump chambers 11, 12 of each stage, and are configured so that they can rotate without contacting each other and discharge the drawn-in gas. One of the pair of gears is attached to the driving-side rotating shaft 20A, and the other is attached to the driven-side rotating shaft 20B. The gears mesh within a bearing body 40, which also serves as a gearbox.

[0024] As shown in FIG. 5 and other figures, the multi-stage biaxial rotary pump according to the present invention has the following configuration in a front-to-rear inter-stage section 30 provided between an exhaust-side end wall 11a of the front-stage pump, where an exhaust port 11b of the front-stage pump chamber is provided, and an intake-side end wall 12a of the rear-stage pump, where an intake port 12b of the rear-stage pump chamber is provided.

[0025] That is, the system is provided with an inter-stage communication chamber 33 that is provided midway between the two rotating shafts 20A, 20B in the left-right direction and serves as a passage that connects the exhaust port 11 b of the front-stage pump chamber and the intake port 12 b of the rear-stage pump chamber so as to pass up and down between the two rotating shafts; a one-side inter-stage liquid-cooling flow path 31 that is formed on one side of the two rotating shafts 20A, 20B in the left-right direction as a flow path through which coolant can flow from the bottom to the top; and a other-side inter-stage liquid-cooling flow path 32 that is formed on the other side of the two rotating shafts 20A, 20B in the left-right direction as a flow path through which coolant can flow from the bottom to the top.

[0026] This allows the direction of the upward flow of the coolant to be aligned with the direction in which the coolant rises as it is heated, allowing the coolant to flow smoothly and making it easier to evacuate bubbles that form as the coolant flows upward, thereby achieving and maintaining a high level of cooling performance. Therefore, the multi-stage biaxial rotary pump according to the present invention has the advantageous effect of rationally preventing the rotor and pump body from overheating due to water cooling.

[0027] Furthermore, in this embodiment, the first-side interstage liquid-cooling flow passage 31 and the second-side interstage liquid-cooling flow passage 32 are flat, wide in the left-right direction and narrow in the front-rear direction, and are flow passages (openings) with a larger cross-sectional area than the piping (coolant liquid communication passage 35, etc.). This increases the surface area over which the coolant comes into contact with the exhaust-side end wall 11a of the front pump and the intake-side end wall 12a of the rear pump, thereby efficiently cooling the pump chambers 11, 12. Note that the "front-rear direction" in this embodiment refers to the direction in which the front-stage pump chamber 11 and the rear-stage pump chamber 12 overlap in the front and rear, and is the direction along the axial lines of the rotating shafts 20A, 20B. Furthermore, the first-side interstage liquid-cooling flow passage 31 and the second-side interstage liquid-cooling flow passage 32 are formed in a single layered portion between the front-stage pump chamber 11 and the rear-stage pump chamber 12, and both the front and rear surfaces of these flow passages are used for cooling, resulting in a structure in which condensation is less likely to occur on the surfaces. Therefore, compared to a single-stage two-shaft rotary pump, it is possible to eliminate the need for dedicated parts to prevent condensation, and costs can also be reduced.

[0028] As described above, according to the present invention, the pump chambers 11 and 12 can be cooled by water cooling, thereby efficiently cooling the front rotors 21A and 21B and the rear rotors 22A and 22B simultaneously, thereby appropriately preventing contact between the two rotating rotors due to thermal expansion (rotor-to-rotor contact). Furthermore, due to the efficient cooling effect, cooling related to the pump exhaust, which is required in the single-stage water-cooled pump described in Patent Document 2, is not required, thereby reducing the number of parts and achieving cost reduction. In the semiconductor manufacturing industry, cooling the front exhaust section (the section including the exhaust port 11b of the front pump chamber) can cause a concern of precipitation of a sublimation reaction by-product (ammonium chloride). However, this precipitation can be suppressed by, for example, using a bypass circuit or adjusting the flow rate of the cooling water in the front exhaust section's cold water circuit by inverter control to prevent excessive cooling.

[0029] The upstream pump chamber 11 is made up of a upstream pump chamber cylinder portion 11c having an upstream pump chamber suction port 11e at its top, a upstream pump bearing-side end wall 11d, and a upstream pump exhaust-side end wall 11a having an upstream pump chamber exhaust port 11b (see FIG. 2, etc.). The downstream pump chamber 12 (see FIG. 2) is made up of a downstream pump suction-side end wall 12a (see FIG. 5) having an downstream pump chamber suction port 12b (see FIG. 5), a downstream pump chamber cylinder portion 12c (see FIG. 2), and a downstream pump exhaust-side end wall 12d (see FIG. 2) having an downstream pump chamber exhaust port 12e (see FIG. 2).

[0030] 5 , the upper side of one side interstage liquid-cooling flow passage 31 and the lower side of the other side interstage liquid-cooling flow passage 32 are connected by a coolant communicating passage 35 so that the coolant is introduced from the lower side of one side interstage liquid-cooling flow passage 31 through coolant inlet connecting portion 31 f and discharged at the upper side, and then introduced from the lower side of the other side interstage liquid-cooling flow passage 32 and discharged to the upper side. More specifically, the coolant communicating passage 35 formed by piping is connected from the liquid-cooling flow passage connecting portion 31 d provided on the closing plate 31 b at the top of one side interstage liquid-cooling flow passage 31 to the coolant inlet connecting portion 32 f provided at the lower part of the other side interstage liquid-cooling flow passage 32, forming a flow passage through which the coolant flows from one side interstage liquid-cooling flow passage 31 through the other side interstage liquid-cooling flow passage 32.

[0031] This allows a water-cooled cooling circuit to be set up so that cooling water is circulated away from the part that is more likely to become hot (for example, the part on the drive side rotating shaft 20A side) to be cooled preferentially, thereby preventing the rotor and pump body from overheating in a more balanced manner.

[0032] In addition, bubbles may be generated as the coolant circulates. The upward flow of the coolant has the effect of pushing up the bubbles. Because the bubbles are gaseous and lightweight, they exert an upward force within the coolant, and the upward movement of the bubbles is in the same direction as the upward flow of the coolant. This facilitates the upward movement of the bubbles. Therefore, the provision of exhaust valves 31e and 32e (see FIG. 5 ), which serve as exhaust means for discharging (exhausting) the bubbles to the outside from the upper ends of the first interstage liquid-cooling flow passage 31 and the second interstage liquid-cooling flow passage 32, allows for easy and proper exhaust. In this embodiment, the exhaust valve 31e is connected to the upper part of the liquid-cooling flow passage connection 31d provided on the upper side of the upper closure plate 31b, and the exhaust valve 32e is connected to the upper part of the liquid-cooling flow passage connection 32d provided on the upper side of the upper closure plate 32b. In this embodiment, the upper closure plate 31b, the upper closure plate 32b, and the upper closure plate 33b that closes the upper end of the inter-stage communication chamber 33 between them are integrally formed as a single plate as shown in Figures 2 and 5, but of course they may also be formed separately, such as in the case of compatibility with the air-cooled type described below.

[0033] In this embodiment, as shown in FIG. 4 , a bearing liquid-cooling passage 42 is provided in the bearing 41 so that the coolant can be introduced into the one-side interstage liquid-cooling passage 31 after cooling the bearing 41, which supports the two rotating shafts 20A, 20B on the side to which the driving force is transmitted. The bearing liquid-cooling passage 42 in this embodiment has a flat opening that is wide in the vertical direction and narrow in the front-to-rear direction, thereby increasing the surface area and enabling efficient cooling. Furthermore, the bearing liquid-cooling passage 42 is provided below the bearing body 40 (bearing 41), which is the gearbox, thereby efficiently cooling the lubricating oil in the gearbox. The coolant is introduced from an external coolant source into the bearing liquid-cooling passage 42 through a coolant inlet 45 (see FIGS. 6 and 7 ), and is then connected from the bearing liquid-cooling passage 42 to the coolant inlet connector 31f of the one-side interstage liquid-cooling passage 31 via a coolant connecting pipe 43 (see FIG. 4 ). The cooling liquid that has passed through the other-side interstage liquid-cooling flow passage 32 is discharged from the device through a flow passage (pipe) connected to the liquid-cooling flow passage connection portion 32d.

[0034] With this, the coolant first flows through the bearing liquid-cooling passage 42 and then through the one-side interstage liquid-cooling passage 31, so that a coolant with a lower temperature flows through the bearing liquid-cooling passage 42, thereby enabling the entire multi-stage biaxial rotary pump to be cooled in a balanced, rational, and efficient manner. That is, the bearing 41 is a portion that is kept at a lower temperature than the heated pump chambers 11 and 12, and by flowing the coolant through this portion first, it is possible to rationally cool it with the coolant at a lower temperature. In addition, an exhaust valve 44 is connected to the upper part of the passages that make up the coolant connecting pipe 43, so that bubbles generated in the passages including the bearing liquid-cooling passage 42 can be properly exhausted, thereby improving cooling efficiency.

[0035] In this embodiment, as shown in FIG. 2 and other figures, the front and rear interstage section 30 includes the exhaust side end wall 11 a of the front-stage pump and the intake side end wall 12 a of the rear-stage pump, and the front and rear interstage section 30 is integrally provided with an interstage communication chamber 33, one-side interstage liquid-cooling flow path 31, and the other-side interstage liquid-cooling flow path 32.

[0036] By integrating them in this manner, the cooling circuit having as its components the one-side interstage liquid-cooling flow path 31 and the other-side interstage liquid-cooling flow path 32 can be integrated with the rear-stage cylinder portion 12c of the rear-stage pump chamber that constitutes the rear-stage pump chamber 12, as shown in FIG. 2, for example, which makes it possible to reduce the number of parts and thereby the number of assembly steps, thereby achieving cost reduction.

[0037] 5 and 13, the one-side interstage liquid-cooling flow passage 31 and the other-side interstage liquid-cooling flow passage 32 are provided as flow passages through which the coolant flows by being closed at their upper and lower ends by upper and lower closing plates 31b, 31c, 32b, and 32c, respectively (see FIG. 5), and are provided so that by removing the upper and lower closing plates 31b, 31c, 32b, and 32c, they become the one-side interstage air-cooling flow passage 31A and the other-side interstage air-cooling flow passage 32A through which cooling air flows (see FIG. 13). Note that in this embodiment, the upper closing plate 33b and the lower closing plate 33c of the interstage communicating chamber 33 close the upper and lower ends of the interstage communicating chamber 33, respectively, in both the water-cooled and air-cooled cases.

[0038] This allows parts to be shared with a two-stage air-cooled vacuum pump configured to cool the pump chambers 11, 12 and the rotors 21A, 21B, 22A, 22B with cooling gas, thereby reducing total costs. Also, as in this embodiment, the openings that form the flow paths of the one-side interstage liquid-cooling flow path 31 and the other-side interstage liquid-cooling flow path 32, which are components of the cooling circuit, are widened, which has the advantage that cooling air (cooling gas) can be effectively circulated when a chilled water circuit is not required.

[0039] Furthermore, in this embodiment, the multistage two-shaft rotary pump described above is a multistage claw pump, and as shown in Fig. 5, of the one-side interstage liquid-cooling flow passage 31 and the other-side interstage liquid-cooling flow passage 32, the one-side interstage liquid-cooling flow passage 31 is provided as the side to which the coolant is introduced first, and is provided close to the exhaust port 11b (see Fig. 2) of the previous-stage pump chamber which is arranged eccentrically as a claw pump. In other words, this is a multistage claw pump in which the lower part of the one-side interstage liquid-cooling flow passage 31 on the side to which the coolant is introduced first is provided below the exhaust-side end wall 11a (see Fig. 2) of the previous-stage pump, offset to one side in the left-right direction, and close to the part where the exhaust port 11b (see Fig. 2) of the previous-stage pump chamber is provided.

[0040] This allows a water-cooled cooling circuit to be provided so that cooling liquid (such as cooling water) is circulated from the area that is likely to become hot (for example, the area of ​​the exhaust port 11b of the front-stage pump chamber, which is located on one side) to provide preferential cooling, thereby preventing the rotor and the pump body from overheating in a more balanced manner.In this embodiment, the exhaust gas discharged from the exhaust port 12e of the rear-stage pump chamber (see FIG. 2) is configured to pass through the exhaust port 61 (see FIG. 8) of the muffler 60, the exhaust pipe 62 (see FIG. 15), the second muffler 63, and the exhaust port 64 (see FIG. 15).

[0041] Next, a second embodiment (an air-cooled two-stage two-shaft rotary pump) will be described with reference to Figures 9 to 15. The same reference numerals will be used to designate components equivalent to those of the first embodiment (a water-cooled two-stage two-shaft rotary pump), and descriptions thereof will be omitted.

[0042] In the multistage two-shaft rotary pump according to the present invention, as shown in FIG. 10, a front-rear interstage section 30 is provided between an exhaust side end wall 11a of the front pump where an exhaust port 11b of the front pump chamber is provided and an intake side end wall 12a of the rear pump where an intake port 12b of the rear pump chamber is provided. In the front-rear interstage section 30, a passage is provided in the middle of the two rotary shafts 20A, 20B in the left-right direction, which connects the exhaust port 11b of the front pump chamber with the intake port 12b of the rear pump chamber. an inter-stage communication chamber 33 (see FIG. 13 ), a one-side inter-stage air-cooling flow passage 31A (see FIGS. 10 and 13 , etc.) formed on one side of the two rotating shafts 20A, 20B in the left-right direction as a flow passage through which cooling air can flow from the bottom to the top, and an other-side inter-stage air-cooling flow passage 32A (see FIGS. 10 and 13 , etc.) formed on the other side of the two rotating shafts 20A, 20B in the left-right direction as a flow passage through which cooling air can flow from the bottom to the top.

[0043] This allows the direction of the upward flow of cooling air to be aligned with the direction in which the cooling air rises as it is heated, allowing the cooling air to flow smoothly and maintaining a high level of cooling performance. Therefore, the multi-stage biaxial rotary pump according to the present invention has the advantageous effect of rationally preventing the rotor and pump body from overheating due to air cooling.

[0044] Furthermore, similar to the first embodiment, the one-side interstage air-cooling passage 31A and the other-side interstage air-cooling passage 32A are flat passages (openings) that are wide in the left-right direction and narrow in the front-rear direction, and have a larger cross-sectional area than the piping. Therefore, the surface area over which the cooling air comes into contact with the exhaust-side end wall 11 a of the front-stage pump and the intake-side end wall 12 a of the rear-stage pump is increased, enabling efficient cooling of the pump chambers 11, 12.

[0045] As described above, according to the present invention, the front rotors 21A, 21B and the rear rotors 22A, 22B can be efficiently cooled simultaneously by air cooling, which makes it possible to effectively prevent the two rotating rotors from coming into contact with each other due to thermal expansion (inter-rotor contact).

[0046] In this embodiment, the front and rear inter-stage section 30 includes the front-stage pump exhaust-side end wall 11 a and the rear-stage pump suction-side end wall 12 a, and the inter-stage communication chamber 33, the one-side inter-stage air-cooling passage 31A, and the other-side inter-stage air-cooling passage 32A are integrally formed in the front and rear inter-stage section 30. This reduces the number of parts and reduces manufacturing costs, as in the first embodiment.

[0047] In addition, in this embodiment, a cooling gap 50 (see Figures 12, 14, 15, etc.) between the body parts is provided in a region corresponding to the periphery of the two rotating shafts 20A, 20B between the pump chamber body part 10 in which the multi-stage pump chambers 11, 12 are provided and the bearing body part 40 in which the bearing part 41 is provided for supporting the two rotating shafts 20A, 20B on the side to which the driving force is transmitted (the drive motor 25 side), allowing cooling air to flow from the bottom to the top.

[0048] This allows the direction of the upward flow of cooling air to be aligned with the direction in which the cooling air rises as it is heated, allowing the cooling air to flow smoothly and maintaining a high level of cooling performance. Therefore, the multi-stage biaxial rotary pump according to the present invention has the advantageous effect of rationally preventing the pump chamber body 10 and the bearing body 40 from being overheated by air cooling.

[0049] In this embodiment, a centrifugal blower fan 26 is attached to a coupling 25a provided to transmit the driving force of a drive motor 25 on one of the two rotating shafts 20A, 20B, and a cooling air guide 55 (see FIG. 15) is provided to guide the airflow generated by the centrifugal blower fan 26 as cooling air so that it flows from the bottom to the top through the one-side interstage air-cooling passage 31A, the other-side interstage air-cooling passage 32A, and the cooling gap 50 between the body portions. The centrifugal blower fan 26 is disposed inside a fan cover 27, and is configured to discharge the cooling airflow from an air outlet 27a (see FIG. 12, etc.) provided below. The pump body of this embodiment is mounted on and supported by a base portion 16, as shown in FIG. 15, and is covered by a pump body cover 15.

[0050] This cooling air guide section 55 can appropriately guide the cooling air generated by the centrifugal blower fan 26 and send the cooling air to the one-side interstage air cooling passage 31A, the other-side interstage air cooling passage 32A, and the cooling gap 50 between the body portions, thereby efficiently cooling the multi-stage two-shaft rotary pump according to the present invention. Therefore, the front-stage rotors 21A, 21B and the rear-stage rotors 22A, 22B can be efficiently cooled simultaneously, and contact between the two rotating rotors due to thermal expansion (inter-rotor contact) can be preferably prevented.

[0051] Furthermore, the multi-stage two-shaft rotary pump of this embodiment is a multi-stage claw pump, and as shown in FIG. 13 , of the one-side interstage air-cooling flow passage 31A and the other-side interstage air-cooling flow passage 32A, the one-side interstage air-cooling flow passage 31A is provided closer to the exhaust port 11b (see FIG. 10 ) of the previous-stage pump chamber, which is arranged eccentrically as a claw pump.

[0052] 13, the exhaust port 11b of the front-stage pump chamber (see FIG. 10), which is the part that is heated the most, is located close to the one-side interstage air-cooling passage 31A, so heat exchange is performed efficiently and the multistage claw pump can be cooled in a well-balanced manner as a whole, achieving the same effects as those described above. Also, in this embodiment, the thickness of the front and rear interstage section 30 that forms the one-side interstage air-cooling passage 31A is thin (see FIG. 13) in accordance with the shape of the exhaust port 11b of the front-stage pump chamber (see FIG. 10), which also allows efficient cooling by the cooling air flowing through the one-side interstage air-cooling passage 31A.

[0053] In the two embodiments described above, the two-stage rotors 21A, 21B, 22A, 22B are supported in a cantilevered manner via the two rotating shafts 20A, 20B, but the present invention is not limited to this and can also be effectively applied to multi-stage two-shaft rotary pumps, including multi-stage claw pumps, in which the two rotating shafts 20A, 20B are supported from both sides.

[0054] The present invention has been described above in various ways using preferred embodiments, but the present invention is not limited to these embodiments, and it goes without saying that many modifications can be made within the scope of the invention without departing from the spirit of the invention.

[0055] DESCRIPTION OF SYMBOLS 10 Pump chamber body 11 Forward stage pump chamber 11a Forward stage pump exhaust side end wall 11b Forward stage pump chamber exhaust port 11c Forward stage pump chamber cylinder portion 11d Forward stage pump bearing side end wall 11e Forward stage pump chamber suction port 12 Rear stage pump chamber 12a Rear stage pump suction side end wall 12b Rear stage pump chamber suction port 12c Rear stage pump chamber cylinder portion 12d Rear stage pump exhaust side end wall 12e Rear stage pump chamber exhaust port 15 Pump body cover 16 Base portion 20A Rotating shaft (driving side rotating shaft) 20B Rotating shaft (driven side rotating shaft) 21A Forward stage rotor 21B Forward stage rotor 22A Rear stage rotor 22B Rear stage rotor 25 Drive motor 25a Coupling 26 Centrifugal blower fan 27 Fan cover portion 27a Air outlet 30 Front and rear interstage section 31 One-side interstage liquid cooling flow passage 31A One-side interstage air cooling flow passage 31b Upper closing plate 31c Lower closing plate 31d Liquid cooling flow passage connection portion 31e Exhaust valve 31f Cooling liquid inlet connection portion 32 Other-side interstage liquid cooling flow passage 32A Other-side interstage air cooling flow passage 32b Upper closing plate 32c Lower closing plate 32d Liquid cooling flow passage connection portion 32e Exhaust valve 32f Cooling liquid inlet connection portion 33 Interstage communication chamber 33b Upper closing plate 33c Lower closing plate 35 Cooling liquid communication passage 40 Bearing portion body portion (gear box) 41 Bearing portion 42 Bearing portion liquid cooling flow passage 43 Cooling liquid connection pipe 44 Exhaust valve 45 Cooling liquid inlet 50 Cooling gap between body portions 55 Cooling air guide portion 60 Muffler 61 Muffler outlet 62 Exhaust pipe 63 Second muffler 64 Exhaust outlet

Claims

1. A multistage two-shaft rotary pump comprising: multiple stages of pump chambers, each having a cross-sectional shape formed by overlapping portions of two circles in the left-right direction; two rotary shafts arranged in parallel within the pump chamber of each stage and rotated at the same speed in opposite directions by a pair of gears; and two rotors for each stage arranged in the pump chamber of each stage corresponding to the two rotary shafts and formed so as to rotate without contact with each other and discharge sucked gas; wherein, in a front-rear interstage section provided between an exhaust side end wall of the front-stage pump where an exhaust port of the front-stage pump chamber is provided and an intake side end wall of the rear-stage pump where an intake port of the rear-stage pump chamber is provided, an interstage communication chamber provided midway in the left-right direction between the two rotary shafts as a passage communicating the exhaust port of the front-stage pump chamber with the intake port of the rear-stage pump chamber; and a one-side interstage air-cooling flow path formed on one side in the left-right direction of the two rotary shafts as a flow path through which cooling air can flow from the lower side to the upper side. a second interstage air-cooling flow passage formed on the other side of the two rotary shafts in the left-right direction as a flow passage for flowing cooling air from the lower side to the upper side.

2. A multi-stage two-shaft rotary pump according to claim 1, characterized in that the front and rear inter-stage section includes an exhaust side end wall of the front-stage pump and an intake side end wall of the rear-stage pump, and the front and rear inter-stage section is integrally formed so as to form the inter-stage communication chamber, the one-side inter-stage air-cooling flow passage, and the other-side inter-stage air-cooling flow passage.

3. A multi-stage two-shaft rotary pump according to claim 1, characterized in that a cooling gap is provided between the pump chamber body portion in which the multi-stage pump chambers are provided and the bearing body portion in which the bearing portions that support the two rotating shafts are provided, in a region corresponding to the periphery of the two rotating shafts, allowing cooling air to flow from the bottom to the top.

4. A multi-stage two-shaft rotary pump according to claim 3, characterized in that a centrifugal blower fan is attached to a coupling provided to transmit the driving force of a drive motor on one of the two rotary shafts, and a cooling air guide is provided to use the air flow generated by the centrifugal blower fan as cooling air and to guide it from the bottom to the top through the one-side interstage air cooling flow passage, the other-side interstage air cooling flow passage, and the cooling gap between the body portion.

5. A multi-stage claw pump wherein the multi-stage two-shaft rotary pump according to claims 1 to 4 is a multi-stage claw pump, and of the one-side interstage air-cooling passage and the other-side interstage air-cooling passage, the one-side interstage air-cooling passage is provided closer to the exhaust port of the front-stage pump chamber, which is eccentrically arranged as a claw pump.

6. A multistage two-shaft rotary pump comprising: multiple stages of pump chambers, each having a cross-sectional shape formed by overlapping portions of two circles in the left-right direction; two rotary shafts arranged in parallel within the pump chamber of each stage and rotated at the same speed in opposite directions by a pair of gears; and two rotors arranged in each stage corresponding to the two rotary shafts and formed so as to rotate without contact with each other and discharge sucked gas; wherein the pump comprises, in a front-rear interstage section provided between the exhaust side end wall of the front-stage pump where the exhaust port of the front-stage pump chamber is provided, and the intake side end wall of the rear-stage pump where the intake port of the rear-stage pump chamber is provided, an interstage communication chamber provided as a passage communicating the exhaust port of the front-stage pump chamber with the intake port of the rear-stage pump chamber, midway in the left-right direction between the two rotary shafts and passing vertically between the two rotary shafts; and a one-side interstage liquid cooling flow path formed on one side of the two rotary shafts in the left-right direction as a flow path through which coolant can flow from below to above. a second interstage liquid-cooling flow passage formed on the other side of the two rotary shafts in the left-right direction as a flow passage through which a cooling liquid can flow from the lower side to the upper side.

7. A multi-stage two-shaft rotary pump according to claim 6, characterized in that the upper side of the one-side interstage liquid-cooled flow passage and the lower side of the other-side interstage liquid-cooled flow passage are connected by a coolant communicating passage so that the coolant is introduced from the lower side of the one-side interstage liquid-cooled flow passage and discharged at the upper side, and then introduced from the lower side of the other-side interstage liquid-cooled flow passage and discharged from the upper side.

8. A multi-stage two-shaft rotary pump according to claim 6, characterized in that a bearing liquid cooling passage is provided in the bearing section so that the cooling liquid is introduced into the one-side interstage liquid cooling passage after cooling the bearing section that supports the two rotating shafts.

9. A multi-stage two-shaft rotary pump according to claim 6, characterized in that the front and rear interstage sections include an exhaust side end wall of the front stage pump and an intake side end wall of the rear stage pump, and the front and rear interstage sections are integrally formed so as to form the interstage communication chamber, the one-side interstage liquid-cooled flow passage, and the other-side interstage liquid-cooled flow passage.

10. A multi-stage two-shaft rotary pump according to claim 6, characterized in that the one-side interstage liquid-cooling flow passage and the other-side interstage liquid-cooling flow passage are provided as flow passages through which cooling liquid flows by having their upper and lower ends closed by upper and lower closing plates, respectively, and that by removing the upper and lower closing plates, they become one-side interstage air-cooling flow passages and other-side interstage air-cooling flow passages through which cooling air flows.

11. A multi-stage claw pump wherein the multi-stage two-shaft rotary pump according to any one of claims 6 to 10 is a multi-stage claw pump, and wherein, of the one-side interstage liquid-cooling flow path and the other-side interstage liquid-cooling flow path, the one-side interstage liquid-cooling flow path is provided as the side to which the cooling liquid is introduced first, and is provided adjacent to the exhaust port of the previous-stage pump chamber which is eccentrically arranged as a claw pump.

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