Motor system

Abstract

This provides a motor system capable of effectively cooling mechanical seals. [Solution] A motor system S for cooling a mechanical seal 30 provided on the rotating shaft 13 of a motor M, comprising a mechanical seal 30, a coolant flow path 41 for guiding coolant L to the vicinity of the mechanical seal 30, and a refrigerant circulation circuit 60 for circulating refrigerant R to the motor M to cool the motor M, wherein a cooling jacket passage 25 is formed in the casing 20 for flowing coolant L so as to pass near a fixed ring 32 and / or secondary seal 33, and the coolant flow path 41 has a coolant heat exchange section 45 for exchanging heat between the coolant L in the coolant flow path 41 and the refrigerant R in the refrigerant circulation circuit 60, and is configured to guide at least the coolant L cooled by the coolant heat exchange section 45 to the cooling jacket passage 25.

Description

Technical Field

[0001] The present invention relates to a motor system, and more particularly to a motor system for cooling a seal member of a rotating shaft of an electric motor.

Background Art

[0002] A configuration using a mechanical seal at the shaft penetration portion of a power electric motor has been proposed (see Patent Document 1). A mechanical seal is generally configured such that two annular members (seal ring, mating ring) slide while being pressed against each other in the axial direction. For this reason, these annular members are heated by the frictional heat generated on the sliding surface, and thus are formed of a material having a high heat resistance temperature (for example, a ceramic-based material).

[0003] On the other hand, secondary seals (O-rings, brackets, etc.) that form part of the mechanical seal are used to attach the annular members to a structure (housing, cover member, etc.) or the rotating shaft. The secondary seal can absorb deformation and vibration of the motor system. The secondary seal is formed of a material having a lower heat resistance temperature (for example, rubber, resin, etc.) than the materials forming the structure (for example, an iron-based material) or the annular member (for example, a ceramic-based material).

[0004] In recent years, with the increase in the rotational speed of power electric motors mounted on vehicles (for example, exceeding 30,000 rpm), when a mechanical seal is used in such a high-speed motor, the peripheral speed or rotational speed at the sliding portion of the mechanical seal becomes higher. In this case, more heat will be generated in the mechanical seal.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the structure described in Patent Document 1, a portion of the annular member of the mechanical seal that is exposed into the motor chamber is cooled by a coolant, which may prevent efficient cooling of the secondary seal (not shown). In particular, in high-speed motors where greater heat is generated in the sliding parts, the temperature of the secondary seal may exceed its heat resistance temperature in the structure described in Patent Document 1. For this reason, the durability of the entire mechanical seal (especially the secondary seal) may be compromised in the conventional structure.

[0007] The present invention was made to solve the above-mentioned technical problems and aims to provide a motor system capable of effectively cooling a mechanical seal. [Means for solving the problem]

[0008] To achieve the above objective, the present invention provides a motor system for cooling a mechanical seal provided on the rotating shaft of a motor, comprising: a rotating ring attached to the rotating shaft and a stationary ring fixed to the motor casing via a secondary seal, wherein the rotating ring and the stationary ring are configured to abut against each other at a predetermined pressure in the axial direction of the rotating shaft; a tank for storing coolant to be supplied to the mechanical seal; a pump for pumping the coolant stored in the tank; a coolant flow path for guiding the coolant pumped by the pump to the vicinity of the mechanical seal; and a refrigerant circulation circuit for circulating refrigerant through the motor to cool the motor, wherein a cooling jacket passage is formed in the casing for allowing the coolant to flow so as to pass near the stationary ring and / or secondary seal, the coolant flow path has a coolant heat exchange section for exchanging heat between the coolant in the coolant flow path and the refrigerant in the refrigerant circulation circuit, and is configured to guide at least the coolant cooled by the coolant heat exchange section to the cooling jacket passage.

[0009] In the present invention configured as described above, a cooling jacket passage for passing coolant to cool the mechanical seal is formed in the casing, and the casing is configured to function as a cooling jacket. Furthermore, in the present invention, the coolant heat exchange section is configured to guide the coolant cooled by the refrigerant in the refrigerant circulation circuit for cooling the motor to the cooling jacket passage. With this configuration, the present invention can effectively cool the mechanical seal and suppress its deterioration.

[0010] Furthermore, in the present invention, preferably, the coolant flow path is configured to guide the coolant into the cooling jacket passage and to spray the coolant onto the mechanical seal. With the present invention configured in this way, the mechanical seal can be cooled and lubricated by the coolant.

[0011] Furthermore, in the present invention, preferably, the cooling jacket passage includes an inlet passage extending axially from the inner surface of the casing to receive a coolant, a cooling passage communicating with the inlet passage and extending around the rotating shaft within the casing to allow the coolant to pass through, and an outlet passage communicating with the cooling passage for discharging the coolant from the cooling passage. With the present invention configured in this way, it is possible to cool the mechanical seal attached to the casing with the coolant passing through the cooling jacket passage while suppressing stress concentration that may occur in the casing due to the formation of the cooling jacket passage.

[0012] Furthermore, in the present invention, the coolant is preferably a lubricating oil. With the present invention configured in this way, the coolant for lubrication and cooling of the mechanical seal can be supplied to the mechanical seal using a common flow path, thus simplifying the device configuration.

[0013] Furthermore, in the present invention, the refrigerant is preferably a CO2 refrigerant. With the present invention configured in this way, it is possible to reduce the environmental burden by using a natural refrigerant.

[0014] Furthermore, in the present invention, preferably, the refrigerant is stored in a tank together with the coolant, and the refrigerant circulation circuit includes a compressor that compresses the refrigerant supplied from the tank, a heat exchanger that dissipates heat from the compressed refrigerant, and an expansion valve that expands the refrigerant that has dissipated heat, and is configured to supply the expanded refrigerant to the motor and the coolant heat exchange section. With the present invention configured in this way, a low-temperature refrigerant can be generated by the refrigerant circulation circuit, and the coolant can be effectively cooled in the coolant heat exchange section.

[0015] Furthermore, in the present invention, preferably, the expansion valve includes at least a first expansion valve and a second expansion valve, and the refrigerant circulation circuit is configured to branch to the first expansion valve and the second expansion valve downstream of the heat exchanger, with the refrigerant expanded by the first expansion valve being supplied to the motor and the refrigerant expanded by the second expansion valve being supplied to the coolant heat exchange section. With the present invention configured in this way, cooling of the motor and cooling of the coolant in the coolant heat exchange section can be effectively performed.

[0016] Furthermore, in the present invention, preferably, the coolant flow path comprises a first branch flow path passing through the coolant heat exchange section, a second branch flow path bypassing the coolant heat exchange section, and a switching valve that selectively switches between the first branch flow path and the second branch flow path. The invention further comprises a temperature sensor for measuring the temperature of the mechanical seal and a controller for controlling the switching valve. The controller is configured to control the switching valve so that the coolant passes through the first branch flow path when the temperature measured by the temperature sensor is above a predetermined threshold temperature. With the present invention configured in this way, when the temperature of the mechanical seal is low and there is no need to cool the coolant with a refrigerant, the operating load of the refrigerant circulation circuit can be reduced, thereby saving power. [Effects of the Invention]

[0017] According to the motor system of the present invention, the mechanical seal can be sufficiently cooled. [Brief explanation of the drawing]

[0018] [Figure 1]This is a schematic configuration diagram of a motor system according to an embodiment of the present invention. [Figure 2] This is an electrical block diagram of a motor system according to an embodiment of the present invention. [Figure 3] This is an explanatory diagram of a refrigeration cycle of a motor system according to an embodiment of the present invention. [Figure 4] This is a cross-sectional view showing an attachment structure of a mechanical seal according to an embodiment of the present invention. [Figure 5] This is a partial cross-sectional view of an end cover according to an embodiment of the present invention. [Figure 6] This is a view taken in the direction of the arrow of line VI-VI in FIG. 5. [Figure 7] This is a partial cross-sectional view of a casing according to an embodiment of the present invention. [Figure 8] This is a flowchart showing a processing flow of a motor system according to an embodiment of the present invention. [Figure 9] This is a graph showing the relationship between the motor rotation speed and the temperature of the mechanical seal. [Figure 10] This is a time chart of various physical quantities accompanying the processing flow of a motor system according to an embodiment of the present invention. [Figure 11] This is a partial cross-sectional view of an end cover according to a modified example of an embodiment of the present invention. [Figure 12] This is a cross-sectional view showing an attachment structure of a mechanical seal according to a modified example of an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, a motor system according to an embodiment of the present invention will be described with reference to the accompanying drawings. [Configuration of the System] First, the overall configuration of the motor system S according to this embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic diagram of the motor system according to this embodiment, and Figure 2 is an electrical block diagram of the motor system. The motor system S shown in Figure 1 is configured to supply coolant to a mechanical seal incorporated in a motor M used to drive a vehicle such as an electric vehicle, and to supply refrigerant to the motor M (particularly the stator and rotor).

[0020] Therefore, the motor system S includes a coolant circulation circuit 40 for circulating coolant L through the mechanical seal 30 to cool the mechanical seal 30, and a refrigerant circulation circuit 60 for circulating refrigerant R within the motor M to cool the motor M. In this embodiment, the coolant L and refrigerant R are different fluids; the coolant L is, for example, lubricating oil, and the refrigerant R is, for example, a natural refrigerant such as CO2 refrigerant.

[0021] The coolant circulation circuit 40 is composed of various components arranged on a pipe (or flow path) 41. The flow path 41 includes a tank 42 for storing coolant L, a pump 43 for pumping the coolant L from the tank 42, two switching valves 44a and 44b, a coolant heat exchange section 45, an optional discharge valve 46, an optional regulator 47, and a motor M. Downstream of the regulator 47 is a coolant temperature sensor 48 for measuring the coolant temperature TL of the coolant L flowing into the motor M. Furthermore, a seal temperature sensor 49 is located inside the motor M for detecting the seal temperature T near the mechanical seal 30.

[0022] The flow path 41 branches into a first branch flow path 41a and a second branch flow path 41b between the switching valves 44a and 44b. The first branch flow path 41a is a cooling flow path where the coolant heat exchange section 45 is located. The second branch flow path 41b is a bypass flow path. The switching valves 44a and 44b are configured to operate selectively in conjunction with the cooling valve position (cooling position) and the bypass valve position (bypass position). The switching valves 44a and 44b allow the coolant L pumped from the pump 43 to pass through the first branch flow path 41a in the cooling position and through the second branch flow path 41b in the bypass position. Note that the switching valves 44a and 44b may normally be set to the bypass position.

[0023] The coolant heat exchange unit 45 is configured to cool the coolant L by performing heat exchange between the refrigerant R flowing through the refrigerant circulation circuit 60 and the coolant L. In other words, in the coolant heat exchange unit 45, the coolant L is cooled by the low-temperature refrigerant R by performing heat exchange while the coolant L and refrigerant R pass through separate pipes.

[0024] The discharge valve 46 is an on / off valve that opens and closes the flow path 41, switching between supplying and stopping the coolant L. The regulator 47 is a pressure regulating valve that reduces the supply pressure by the pump 43 to a predetermined pressure and adjusts the flow rate.

[0025] In the coolant circulation circuit 40, coolant L is supplied from the tank 42 by a pump 43 downstream of the flow path 41. After passing through the first branch flow path 41a or the second branch flow path 41b, the coolant L is supplied into the motor M and cools the mechanical seal 30 inside the motor M. The coolant L that has cooled the mechanical seal 30 returns to the tank 42 from the discharge section of the motor M through the discharge flow path 41c.

[0026] Furthermore, the flow path 41 optionally includes a lubrication branch flow path 41d that branches downstream of the pump 43. The coolant L (lubricating oil) flowing through the lubrication branch flow path 41d is supplied to the motor M bearing 14 without going to the switching valve 44a. The coolant L that has lubricated the bearing 14, together with the coolant L that has cooled the mechanical seal 30, flows from the discharge section into the flow path 41c.

[0027] The refrigerant circulation circuit 60 is configured by sharing some components with the coolant circulation circuit 40. The refrigerant circulation circuit 60 forms a refrigeration cycle using refrigerant R (CO2 refrigerant), and includes a tank 42 for storing coolant L and refrigerant R on a piping (or flow path) 61, a compressor 63 for compressing refrigerant R, a heat exchanger (condenser) 64 including a condenser and fan, an optional discharge valve 65, an optional regulator 66, an expansion valve 67a (first expansion valve), an optional expansion valve 67b (second expansion valve), a motor M as an evaporator, and a coolant heat exchange section 45.

[0028] Tank 42 is configured to store both coolant L and refrigerant R, and within tank 42, the liquid coolant L (lubricating oil) and the gaseous refrigerant R (CO2 refrigerant) are separated into upper and lower parts. Therefore, the coolant circulation circuit 40 can take coolant L from the lower part of tank 42, and the refrigerant circulation circuit 60 can take refrigerant R from the upper part of tank 42.

[0029] In this embodiment, the flow path 61 includes a branch flow path 61a, which branches off from the main flow path 61 downstream of the heat exchanger 64 and rejoins the flow path 61 between the tank 42 and the compressor 63. The refrigerant R flowing through the branch flow path 61a does not go towards the motor M, but flows into the coolant heat exchange section 45 through the expansion valve 67b and exchanges heat with the coolant L (i.e., cools the coolant L).

[0030] In this embodiment, the expansion valves 67a and 67b are electronically controlled expansion valves whose valve opening degree can be electronically controlled. The expansion valve 67a can be attached to the flow path 61 or the casing 20. The expansion valve 67a may also be integrated with the casing 20, in which case the expansion valve 67a may be an electronic expansion valve or a pore provided in the casing 20.

[0031] In this embodiment, an expansion valve 67b is provided, but the embodiment is not limited to this. By providing a branch passage 61a that branches off from downstream of the expansion valve 67a and guides the refrigerant R to the coolant heat exchange section 45, the expansion valve 67b may be omitted.

[0032] Furthermore, in this embodiment, the flow path 61 includes another branch flow path 61b that branches off from the main flow path 61 downstream of the heat exchanger 64. The refrigerant R flowing through the branch flow path 61b is reduced to a predetermined pressure by the regulator 66, and then merges with the coolant L flowing through the lubrication branch flow path 41d, or is supplied separately to the bearing 14 of the motor M. Note that if it is not necessary to cool the bearing 14 with the refrigerant R, the branch flow path 61b and the regulator 66 may be omitted.

[0033] In the refrigerant circulation circuit 60, the refrigerant R in the tank 42 is supplied to the motor M through the compressor 63, heat exchanger 64, and expansion valve 67a, and cools the components inside the motor M (especially the stator and rotor). The refrigerant R that has cooled the motor M returns to the tank 42 through the discharge channel 41c from the discharge port of the motor M, just like the coolant L.

[0034] [Motor Configuration] The motor M according to this embodiment is a high-speed motor, configured to operate at a high rotational speed exceeding, for example, 30,000 rpm. The motor M comprises a rotor 11, a stator 12, a rotating shaft (rotor shaft) 13 fixed to the rotor 11 and extending axially, a pair of bearings (sliding bearings) 14 that rotatably support the rotating shaft 13, a casing 20 that houses and supports the rotor 11, stator 12, rotating shaft 13, and bearings 14, etc., and a mechanical seal 30 that seals the space between the casing 20 and the rotating shaft 13. One end of the rotating shaft 13 is connected to a vehicle transaxle (not shown), etc. The motor M also optionally includes a rotational speed sensor or angle sensor (resolver) 15 for detecting the rotor rotational speed of the rotating shaft 13. The casing 20 includes a housing 21 that houses the rotor 11, etc., and an end cover 23 that closes the opening at the axial end of the housing 21.

[0035] The roughly cylindrical stator 12 is constructed by winding coils around a stator core. The rotor 11 has a rotor core and a plurality of permanent magnets attached to the rotor core. The rotating shaft 13 is fixed to the rotor core. The rotor 11 is configured to rotate within the stator 12 together with the rotating shaft 13.

[0036] The mechanical seal 30 seals the space between the end of the rotating shaft 13 and the end cover 23, preventing the leakage of refrigerant R and coolant L from the inside of the casing 20 to the outside. The casing 20 also has internal passages 41 and 61, which are internal passages that receive coolant L from the outside and guide it to the mechanical seal 30 and bearing 14, internal passages that receive refrigerant R from the outside and guide it to the inside of the motor M and bearing 14, and internal passages that serve as a discharge section that guides coolant L and refrigerant R to the discharge passage 41c.

[0037] As shown in Figure 2, the motor system S includes a controller 50, which is a computer with a processor and memory, and receives signals from various sensors (rotor rotation angle, seal temperature, coolant temperature, etc.) and outputs operation signals to each component of the coolant circulation circuit 40 and the refrigerant circulation circuit 60. In this embodiment, the refrigerant circulation circuit 60 is configured to operate continuously while the motor M is in operation.

[0038] [Refrigerant refrigeration cycle] Next, with reference to Figure 3, the refrigeration cycle of the refrigerant R in this embodiment will be described. Figure 3 is a pH diagram of the CO2 refrigerant, where the horizontal axis represents enthalpy and the vertical axis represents pressure. When the pressure and temperature of the CO2 refrigerant are increased from the ambient environment (room temperature, 1 atmosphere) and exceed the critical point (31°C, 7.4 MPa), it becomes a supercritical fluid.

[0039] First, in the refrigeration cycle (ABCD) of this embodiment, a compression stroke (AB) is performed by the compressor 63. The compressor 63 is a rotary type and receives medium-temperature, low-pressure (e.g., 30°C, 4.2 MPa) CO2 refrigerant R (gas; superheated steam) from the tank 42 via the flow path 61 (point A), compresses the received refrigerant R, and discharges high-temperature, high-pressure (e.g., 120°C, 12 MPa) CO2 refrigerant R (supercritical fluid) (point B).

[0040] Next, a cooling stroke (BC) is performed by the heat exchanger 64. The heat exchanger 64 receives high-temperature, high-pressure CO2 refrigerant R (point B), exchanges heat with the external environment (cold air, cooling water, etc.), and generates medium-temperature, high-pressure (e.g., 35°C, 12MPa) CO2 refrigerant R (supercritical fluid) (point C). Next, an expansion stroke (CD) is performed on the medium-temperature, high-pressure CO2 refrigerant R by the expansion valve 67a (or expansion valve 67b). The CO2 refrigerant R expands during the expansion stroke and becomes low-temperature, low-pressure (e.g., 10°C, 4.2MPa) CO2 refrigerant R (gas-liquid mixture; wet vapor) (point D).

[0041] Furthermore, an evaporation process (DA) takes place inside the motor M (or in the coolant heat exchange section 45). The low-temperature, low-pressure CO2 refrigerant R evaporates within the casing 20 by exchanging heat with the high-temperature part of the motor M (or the coolant L in the coolant heat exchange section 45), becoming a medium-temperature, low-pressure CO2 refrigerant R (gas; superheated vapor). This medium-temperature, low-pressure CO2 refrigerant R is returned to the compressor 63 (point A).

[0042] [Mechanical seal mounting structure] Next, the mounting structure of the mechanical seal in this embodiment will be described with reference to Figures 4 to 7. Figure 4 is a cross-sectional view showing the mounting structure of the mechanical seal, Figure 5 is a partial cross-sectional view of the end cover, Figure 6 is a view taken along the line VI-VI in Figure 5, and Figure 7 is a partial cross-sectional view of the casing.

[0043] As shown in Figure 4, an end cover 23 is fixed to the end of the housing 21, and inside the housing 21, a seal arrangement space F is provided between the bearing 14 and the end cover 23, through which the rotating shaft 13 extends in the axial direction Y. A mechanical seal 30 is arranged in this seal arrangement space F. The end cover 23 is disc-shaped and is screwed to the housing 21 in a sealed state with an O-ring 22a in between. The end cover 23 has a cylindrical bulge 24 in the center that protrudes outward in the axial direction Y. A through hole 23a is formed in the bulge 24 through which the rotating shaft 13 is inserted, and a recess 24a is formed inside the bulge 24 for mounting the mechanical seal 30. The bulge 24 has a peripheral wall 24b extending in the axial direction Y from the base, and a torus-shaped (donut-shaped) cover portion 24c that extends radially inward toward the rotating shaft 13 from the tip of the peripheral wall 24b and has a through hole 23a.

[0044] The rotating shaft 13, rotatably supported by the bearing 14, passes through the seal arrangement space F and extends to the outside of the motor M through a through hole 23a provided in the end cover 23. The mechanical seal 30 is configured to seal the space between the seal arrangement space F and the outside of the motor M (in particular, the gap between the rotating shaft 13 and the through hole 23a).

[0045] The mechanical seal 30 comprises a rotating ring 31 attached to the rotating shaft 13, a secondary seal 33 fitted into a recess 24a formed in the end cover 23, and a stationary ring 32 fixed to the end cover 23 via the secondary seal 33. The rotating ring 31 and the stationary ring 32 are annular components having through holes extending in the axial direction Y, and are made of a highly wear-resistant material (e.g., a ceramic material). The rotating shaft 13 is inserted through these through holes.

[0046] The rotating ring 31 is integrated with a cylindrical sliding member 34 that is slidably mounted on the rotating shaft 13, and together with the sliding member 34, it is movable in the axial direction Y of the rotating shaft 13. The rotating ring 31 is also biased in the axial direction Y toward the outside of the motor M by a biasing member 35 fixed to the rotating shaft 13. The biasing member 35 has a coil spring 35a mounted on the rotating shaft 13 and a cylindrical annular member 35b fixed to the rotating shaft 13. The coil spring 35a is compressed in the axial direction Y between the annular member 35b and the rotating ring 31, constantly pressing the rotating ring 31 against the annular member 35b in the axial direction Y. As a result, the rotating ring 31 and the fixed ring 32 come into contact with a predetermined pressure in the axial direction Y.

[0047] The stationary ring 32 is fitted and attached together with the secondary seal 33 into a recess 24a formed in the end cover 23. The secondary seal 33 is a bottomed cylindrical component that is attached to the stationary ring 32, and like the stationary ring 32, it has a through hole formed at its bottom for the rotating shaft 13 to pass through. The secondary seal 33 is made of a material with a predetermined elasticity (e.g., rubber, resin, etc.). The secondary seal 33 has a lower heat resistance temperature than the ceramic material that forms the rotating ring 31 and the stationary ring 32, and the metallic material (especially iron-based material) that forms the casing 20. The secondary seal 33 seals the space between the stationary ring 32 and the recess 24a of the end cover 23, and also absorbs vibrations of the rotating shaft 13.

[0048] The rotating ring 31 and the stationary ring 32 are in contact with each other at their sliding surfaces with a predetermined surface pressure due to the biasing member 35. When the rotating ring 31 rotates together with the rotating shaft 13, the sliding surfaces of the stationary ring 32 and the rotating ring 31 come into contact with each other under the predetermined surface pressure. As a result, frictional heat is generated on the sliding surfaces, causing the rotating ring 31 and the stationary ring 32 to heat up.

[0049] Furthermore, the housing 21 has internal passages 20a formed at multiple locations in the circumferential direction, which serve as flow paths 41 for the coolant circulation circuit 40, guiding the coolant L to the seal placement space F. In addition, the housing 21 has multiple internal passages 20b formed from the seal placement space F toward the bulge 24. On the other hand, the end cover 23 has a cooling jacket passage 25 formed therein for cooling the stationary ring 32 and the secondary seal 33 with the coolant L guided through the internal passages 20a. Therefore, the bulge 24 functions as a cooling jacket. In this embodiment, the cooling jacket passage 25 is formed along the circumferential wall 24b of the bulge 24.

[0050] In this embodiment, the end cover 23 is configured to support the fixed ring 32 and the secondary seal 33, and therefore the end cover 23 is provided with a cooling jacket passage 25. However, the embodiment is not limited to this configuration, and if the housing 21 is configured to support the fixed ring 32 and the secondary seal 33, the housing 21 can also be provided with a cooling jacket passage 25.

[0051] As shown in Figures 5 and 6, the cooling jacket passage 25 has three inlet passages 25a and one outlet passage 25b, which are holes that communicate with the internal flow path 20b and extend axially Y from the base (the surface on the seal placement space side), and a cooling passage 25c that communicates with the inlet passages 25a and the outlet passage 25b and extends at least circumferentially along the peripheral wall 24b. The cooling passage 25c may be formed to connect from the peripheral wall 24b to the lid portion 24c. Therefore, the cooling passage 25c extends at least circumferentially with respect to the secondary seal 33 or the rotating shaft 13.

[0052] In this embodiment, of the four holes, the inlet passage 25a consists of three holes (12 o'clock, 3 o'clock, and 9 o'clock in a front view) that include the highest position in the vertical direction, and the outlet passage 25b consists of the hole at the lowest position in the vertical direction (6 o'clock in a front view).

[0053] In the example shown in Figure 4, the internal flow path 20a extending from top to bottom opens into the seal placement space F through an injection hole 20A with a tapered tip. Additionally, another internal flow path 20b is formed in the housing 21, leading from the seal placement space F to the peripheral wall 24b of the end cover 23. The injection hole 20A is configured to inject the coolant L with a predetermined directionality.

[0054] The coolant L is directed through the internal passage 20a and injected through the injection holes 20A towards the mechanical seal 30 in the seal arrangement space F (particularly the sliding parts of the rotating ring 31 and the stationary ring 32 and the opening of another internal passage 20b), thereby lubricating the mechanical seal 30. In addition, a portion of the coolant L injected from the injection holes 20A is guided through another internal passage 20b to an inlet passage 25a formed in the end cover 23.

[0055] The coolant L enters the cooling passage 25c from the inlet passage 25a, cools the stationary ring 32 and the secondary seal 33 from the circumferential direction, and is discharged again into the seal arrangement space F through the outlet passage 25b and the internal flow path 20b. As shown in Figure 7, the injection hole 20A is positioned so as not to inject the coolant L toward the outlet passage 25b (and the internal flow path 20b communicating with the outlet passage 25b), and is set to have a directional injection pattern so as not to inject the coolant L toward the outlet passage 25b.

[0056] In this embodiment, the housing 21 blocks the axial base of the peripheral wall 24b of the bulging portion 24 of the end cover 23 with an annular closing portion 21a, and another internal flow path 20b is formed in the closing portion 21a. The other internal flow path 20b communicates with the inlet passage 25a. However, at least a part of the closing portion 21a may be removed so that at least a part of the axial base of the peripheral wall 24b of the bulging portion 24 is not blocked by the housing 21. If configured in this way, it is not necessary to form another internal flow path 20b.

[0057] In this embodiment, the fixed ring 32 fixed to the casing 20 is a mating ring that does not move in the axial direction Y, and the rotating ring 31 attached to the rotating shaft 13 is a seal ring that can move in the axial direction Y. However, the embodiment is not limited to this, and a configuration in which the fixed ring 32 is a seal ring and the rotating ring 31 is a mating ring is also possible.

[0058] [Control Flow] Next, the processing flow of the motor system S of this embodiment will be explained with reference to Figures 8 to 10. Figure 8 is a flowchart showing the processing flow of the motor system, Figure 9 is a graph showing the relationship between motor rotation speed and mechanical seal temperature, and Figure 10 is a time chart of various physical quantities associated with the processing flow.

[0059] The controller 50 repeatedly performs the processing flow shown in Figure 8 for cooling the mechanical seal at predetermined intervals. The controller 50 constantly receives signals from various sensors and determines whether the motor rotation speed N is greater than or equal to a predetermined threshold rotation speed Nth (S11). Specifically, the controller 50 can calculate the motor rotation speed N of the rotating shaft 13 based on the rotor rotation angle signal received from the angle sensor 15. In this embodiment, the threshold rotation speed Nth is set so that a positive judgment is made except at extremely low rotation speeds immediately after starting and immediately before stopping the motor M. The threshold rotation speed Nth is set, for example, in the range of 50 to 100 rpm.

[0060] If the judgment in step S11 is negative (S11; No), the controller 50 terminates the process. On the other hand, if the judgment in step S11 is positive (S11; Yes), the controller 50 operates the pump 43 to pump the coolant L towards the motor M (S12). At this time, the controller 50 maintains the valve positions of the switching valves 44a and 44b in the bypass valve position to pass the coolant L through the second branch passage 41b, keeps the discharge valve 46 open, and operates the regulator 47 to reduce the coolant L to a predetermined pressure.

[0061] Next, the controller 50 determines whether the sealing temperature T of the mechanical seal 30 is above a predetermined threshold temperature Tth (S13). Specifically, the controller 50 can receive the sealing temperature T near the mechanical seal 30 from the sealing temperature sensor 49. The threshold temperature Tth is set lower than the heat resistance temperature Tr (e.g., 150°C) of the secondary seal 33, which has a lower heat resistance temperature among the components of the mechanical seal 30. The threshold temperature Tth is set in a range of, for example, 50 to 140°C, or a range of a predetermined temperature (e.g., 100 to 10°C) lower than the heat resistance temperature Tr.

[0062] In this embodiment, the motor M is a motor that operates at a high rotational speed exceeding 30,000 rpm, and deterioration of the mechanical seal 30 due to temperature rise becomes a problem. Figure 9 shows the measurement results using a predetermined mechanical seal, and it can be seen that, without cooling treatment, the temperature of the mechanical seal rises as the motor rotational speed increases. In Figure 9, for example, at 30,000 rpm, it can be seen that the temperature of the mechanical seal exceeds the heat resistance temperature Tr of the secondary seal.

[0063] Therefore, in this embodiment, when the sealing temperature T of the mechanical seal 30 reaches a threshold temperature Tth that is a predetermined temperature lower than the heat resistance temperature Tr of the secondary seal 33, a cooler coolant L is supplied to the cooling jacket passage 25, thereby preventing the sealing temperature T of the mechanical seal 30 (especially the secondary seal 33) from reaching the heat resistance temperature Tr.

[0064] If the determination in step S13 is negative (S13; No), the controller 50 terminates the process. That is, as long as the sealing temperature T of the mechanical seal 30 is low, the coolant L is supplied to the mechanical seal 30 without being cooled in the coolant heat exchange section 45. This reduces the operating load on the compressor 63 and other components, thereby saving power.

[0065] On the other hand, if the determination in step S13 is affirmative (S13; Yes), the controller 50 switches the valve positions Vs of the switching valves 44a and 44b to the valve position Vc for cooling (S14), and passes the coolant L through the first branch flow path 41a. As a result, the coolant L exchanges heat with the refrigerant R in the coolant heat exchange section 45 and is cooled. Therefore, since the coolant L cooled by the refrigerant R is supplied to the cooling jacket passage 25, the mechanical seal 30 is cooled more efficiently, and the secondary seal 33 is suppressed from reaching the heat-resistant temperature Tr.

[0066] Referring to the time chart of FIG. 10, the rotor 11 is rotating at times t1 to t2. In conjunction with this, the valve opening Vd of the discharge valve 46 is changed from the closed position (CL) to the open position (OP). However, since the seal temperature T of the mechanical seal 30 is low (T < Tth), the valve positions Vs of the switching valves 44a and 44b are maintained at the bypass position Pb.

[0067] Also, the rotor 11 is rotating at another time t3 to t6. In conjunction with this, the valve opening Vd of the discharge valve 46 is maintained at the open position (OP). During this period, when the seal temperature T of the mechanical seal 30 reaches the threshold temperature Tth at time t4, the valve positions Vs of the switching valves 44a and 44b are switched from the bypass position Pb to the cooling position Pc. As a result, the coolant L is cooled by the coolant heat exchange section 45 after time t4, and the coolant temperature TL decreases. Along with this, when the seal temperature T of the mechanical seal 30 drops below the threshold temperature Tth at time t5, the valve positions Vs of the switching valves 44a and 44b are switched back to the bypass position Pb.

[0068] [Modified Example of Cooling Jacket Passage] Next, an embodiment relating to a modified version of the present invention will be described with reference to Figure 11. In the modified end cover 23 of Figure 11, the inlet passage 25a and the outlet passage 25b are connected in the circumferential direction and are formed in an annular shape, similar to the annular cooling passage 25c. Even with this configuration, as shown in Figure 4, the coolant L injected from the injection hole 20A reaches the inlet passage 25a through another internal passage 20b and is discharged to the outside through another internal passage 20b below the outlet passage 25b.

[0069] [Variations in the mounting structure of the mechanical seal] Next, an embodiment relating to a modification of the present invention will be described with reference to Figure 12. In the example of Figure 12, the housing 21 is provided with a second internal passage 20c that branches off from the internal passage 20a, in addition to the internal passage 20a that opens into the seal arrangement space F. The internal passage 20c is in direct communication with the cooling jacket passage 25 to supply coolant L. In this embodiment, the internal passage 20a opens into the seal arrangement space F, and its injection hole 20A is formed to have an injection pattern such that the coolant L is sprayed directly onto the sliding portion. On the other hand, the second internal passage 20c extends through the housing 21, similar to the internal passage 20a, but does not open into the seal arrangement space F, and is directly connected to an inlet passage 25a formed in the end cover 23. As a result, in this embodiment, the mechanical seal 30 (especially the secondary seal 33) can be cooled more efficiently by directly supplying coolant L to the cooling jacket passage 25.

[0070] [Mechanism of Action and Effects] Next, the operation and effects of the motor system S according to this embodiment will be described. The motor system S according to this embodiment is a motor system S for cooling a mechanical seal 30 provided on the rotating shaft 13 of a motor M, and comprises a rotating ring 31 attached to the rotating shaft 13 and a stationary ring 32 fixed to the casing 20 of the motor M via a secondary seal 33, wherein the rotating ring 31 and the stationary ring 32 are configured to abut against each other at a predetermined pressure in the axial direction Y of the rotating shaft 13, a tank 42 for storing coolant L to be supplied to the mechanical seal 30, a pump 43 for pumping the coolant L stored in the tank 2, and the coolant pumped by the pump 43. The device comprises a coolant flow path 41 that guides the coolant L to the vicinity of the mechanical seal 30, and a refrigerant circulation circuit 60 that circulates refrigerant R to the motor M to cool the motor M. The casing 20 has a cooling jacket passage 25 formed therein for the coolant L to flow so as to pass near the stationary ring 32 and / or secondary seal 33. The coolant flow path 41 has a coolant heat exchange section 45 for exchanging heat between the coolant L in the coolant flow path 41 and the refrigerant R in the refrigerant circulation circuit 60, and is configured to guide at least the coolant L cooled by the coolant heat exchange section 45 to the cooling jacket passage 25.

[0071] In this embodiment, a cooling jacket passage 25 is formed in the casing 20 through which a coolant L passes to cool the mechanical seal 30, so that the casing 20 functions as a cooling jacket. Furthermore, in this embodiment, the coolant heat exchange section 45 is configured to guide the coolant L, cooled by the refrigerant R in the refrigerant circulation circuit 60 for cooling the motor M, to the cooling jacket passage 25. With this configuration, in this embodiment, the mechanical seal 30 can be effectively cooled and deterioration of the mechanical seal 30 can be suppressed.

[0072] Furthermore, according to this embodiment, the coolant passage 41 is configured to guide the coolant L into the cooling jacket passage 25 and to spray the coolant L onto the mechanical seal 30. In this embodiment, the mechanical seal 30 can be cooled and lubricated by the coolant L.

[0073] Furthermore, according to this embodiment, the cooling jacket passage 25 includes an inlet passage 25a extending axially Y from the inner surface of the casing 20 to receive the coolant L, a cooling passage 25c communicating with the inlet passage 25a and extending around the rotating shaft 13 within the casing 20 to allow the coolant L to pass through, and an outlet passage 25b communicating with the cooling passage 25c to discharge the coolant L from the cooling passage 25c. In this embodiment configured in this way, the mechanical seal 30 attached to the casing 20 can be cooled by the coolant L passing through the cooling jacket passage 25 while suppressing stress concentration that may occur in the casing 20 due to the formation of the cooling jacket passage 25.

[0074] Furthermore, according to this embodiment, the coolant L is lubricating oil. In this embodiment, the coolant L for lubrication and cooling of the mechanical seal 30 can be supplied to the mechanical seal 30 using a common flow path, thus simplifying the device configuration.

[0075] Furthermore, according to this embodiment, the refrigerant R is a CO2 refrigerant. In this embodiment, which is configured in this way, the environmental impact can be reduced by using a natural refrigerant.

[0076] Furthermore, according to this embodiment, the refrigerant R is stored in the tank 42 together with the coolant L, and the refrigerant circulation circuit 60 includes a compressor 63 that compresses the refrigerant R supplied from the tank 42, a heat exchanger 64 that dissipates heat from the compressed refrigerant R, and expansion valves 67a and 67b that expand the dissipated refrigerant R, and is configured to supply the expanded refrigerant R to the motor M and the coolant heat exchange unit 45. In this embodiment configured in this way, the refrigerant circulation circuit 60 generates refrigerant R in a low-temperature state, and the coolant L can be effectively cooled in the coolant heat exchange unit 45.

[0077] Furthermore, according to this embodiment, the expansion valve includes at least a first expansion valve 67a and a second expansion valve 67b, and the refrigerant circulation circuit 60 branches to the first expansion valve 67a and the second expansion valve 67b downstream of the heat exchanger 64, and the refrigerant R expanded by the first expansion valve 67a is supplied to the motor M, and the refrigerant R expanded by the second expansion valve 67b is supplied to the coolant heat exchange section 45. With this configuration, the motor M and the coolant L in the coolant heat exchange section 45 can be cooled effectively.

[0078] Furthermore, according to this embodiment, the coolant flow path 41 includes a first branch flow path 41a that passes through the coolant heat exchange section 45, a second branch flow path 41b that bypasses the coolant heat exchange section 45, and switching valves 44a and 44b that selectively switch between the first branch flow path 41a and the second branch flow path 41b. The embodiment also includes a temperature sensor 49 that measures the temperature T of the mechanical seal 30, and a controller 50 that controls the switching valves 44a and 44b. The controller 50 is configured to control the switching valves 44a and 44b so that the coolant L passes through the first branch flow path 41a when the temperature T measured by the temperature sensor 49 is equal to or greater than a predetermined threshold temperature Tth (S13; Yes). In this embodiment, when the temperature T of the mechanical seal 30 is low and there is no need to cool the coolant L with the refrigerant R, the operating load of the refrigerant circulation circuit 60 can be reduced, thereby saving power. [Explanation of symbols]

[0079] 13 Rotation axis 20 Casing 20a, 20b, 20c Internal flow path 21 Housing 23 End cover 24 Bulge 25 Cooling jacket passage 25a Entrance passage 25b Exit passage 25c cooling passage 30 Mechanical Seals 31 Rotating Ring 32 Fixed ring 33 Secondary seal 40 Coolant circulation circuit 41 Flow path (coolant flow path) 45 Coolant heat exchange section 60 Refrigerant circulation circuit 61 Flow channels F Seal placement space L Coolant M Motor R refrigerant S Motor System

Claims

1. A motor system for cooling a mechanical seal provided on the rotating shaft of a motor, A mechanical seal having a rotating ring attached to the rotating shaft and a stationary ring fixed to the motor casing via a secondary seal, wherein the rotating ring and the stationary ring are configured to abut against each other with a predetermined pressure in the axial direction of the rotating shaft, A tank for storing the coolant supplied to the mechanical seal, A pump for pumping the coolant stored in the tank, A coolant flow path that guides the coolant pumped by the pump to the vicinity of the mechanical seal, The motor is provided with a refrigerant circulation circuit that circulates a refrigerant to cool the motor, The casing has a cooling jacket passage formed therein for allowing the coolant to flow so as to pass near the stationary ring and / or the secondary seal. A motor system wherein the coolant flow path has a coolant heat exchange section for exchanging heat between the coolant in the coolant flow path and the refrigerant in the refrigerant circulation circuit, and is configured to guide at least the coolant cooled by the coolant heat exchange section to the cooling jacket passage.

2. The motor system according to claim 1, wherein the coolant passage is configured to guide the coolant into the cooling jacket passage and to spray the coolant onto the mechanical seal.

3. The aforementioned cooling jacket passage is An inlet passage extending from the inner surface of the casing along the axial direction to receive the coolant, A cooling passage that communicates with the inlet passage and extends around the rotating shaft within the casing, allowing the coolant to pass through, The motor system according to claim 1, further comprising an outlet passage communicating with the cooling passage and for discharging the cooling liquid from the cooling passage.

4. The motor system according to any one of claims 1 to 3, wherein the coolant is a lubricating oil.

5. The aforementioned refrigerant is CO 2 The motor system according to claim 1, wherein the refrigerant is...

6. The refrigerant is stored in the tank together with the coolant. The motor system according to claim 5, wherein the refrigerant circulation circuit includes a compressor for compressing the refrigerant supplied from the tank, a heat exchanger for dissipating heat from the compressed refrigerant, and an expansion valve for expanding the refrigerant that has been dissipated heat, and is configured to supply the expanded refrigerant to the motor and the coolant heat exchange unit.

7. The expansion valve includes at least a first expansion valve and a second expansion valve, The motor system according to claim 6, wherein the refrigerant circulation circuit is configured to branch into a first expansion valve and a second expansion valve downstream of the heat exchanger, the refrigerant expanded by the first expansion valve is supplied to the motor, and the refrigerant expanded by the second expansion valve is supplied to the coolant heat exchange section.

8. The coolant flow path comprises a first branch flow path passing through the coolant heat exchange section, a second branch flow path bypassing the coolant heat exchange section, and a switching valve that selectively switches between the first branch flow path and the second branch flow path. The system further comprises a temperature sensor for measuring the temperature of the mechanical seal and a controller for controlling the switching valve. The motor system according to claim 1, wherein the controller is configured to control the switching valve so that the coolant passes through the second branch passage when the temperature measured by the temperature sensor is equal to or greater than a predetermined threshold temperature.

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