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 the mechanical seal 30 and a refrigerant circulation circuit 60 that cools the motor M by circulating a refrigerant R in a refrigerant passage 61 passing through the motor M, wherein the refrigerant R is a CO2 refrigerant, and the refrigerant circulation circuit 60 includes a tank 42, a compressor 63, a heat exchanger 64, and an expansion valve 67c, and a cooling jacket passage 25 is formed in the casing 20 for flowing the refrigerant R so as to pass near the stationary ring 32 and / or secondary seal 33, and the refrigerant passage 61 is configured to guide the refrigerant R expanded by the expansion valve 67c to at least 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 in a 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 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 a 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 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 at a predetermined pressure in the axial direction of the rotating shaft; and a refrigerant circulation circuit for cooling the motor by circulating a refrigerant through a refrigerant passage that passes through the motor, wherein the refrigerant is a CO2 refrigerant, and the refrigerant circulation circuit includes a tank for storing the refrigerant, 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 dissipated refrigerant, wherein a cooling jacket passage is formed in the casing for allowing the refrigerant to flow so as to pass near the stationary ring and / or secondary seal, and the refrigerant passage is configured to guide the refrigerant expanded by the expansion valve to at least the cooling jacket passage.

[0009] In the present invention configured as described above, a cooling jacket passage for refrigerant is formed in the casing to cool the mechanical seal, and the casing is configured to function as a cooling jacket. Furthermore, in the present invention, the low-temperature, low-pressure refrigerant expanded by the expansion valve is guided 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 cooling jacket passage includes an inlet passage extending axially from the inner surface of the casing to receive a refrigerant, a cooling passage communicating with the inlet passage and extending around the rotating shaft within the casing to allow the refrigerant to pass through, and an outlet passage communicating with the cooling passage for discharging the refrigerant 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 refrigerant 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.

[0011] Furthermore, in the present invention, preferably, the motor has an oil supply unit that sprays lubricating oil onto the sliding part of the mechanical seal, and the outlet passage opens in a position within the internal space of the motor enclosed by the casing where lubricating oil is not directly sprayed from the oil supply unit. With the present invention configured in this way, the refrigerant discharged from the outlet passage is not obstructed by the lubricating oil sprayed from the oil supply unit, so the refrigerant can flow efficiently through the cooling jacket passage.

[0012] Furthermore, in the present invention, preferably, the refrigerant flow path communicates with the cooling jacket passage via the space in which the mechanical seal is located within the casing. With the present invention configured in this way, the mechanical seal can be cooled in the seal space by the refrigerant before the refrigerant is supplied to the cooling jacket passage.

[0013] Furthermore, in the present invention, preferably, the refrigerant flow path communicates with the cooling jacket passage without passing through the space in which the mechanical seal is located within the casing. With the present invention configured in this way, the refrigerant can be efficiently supplied to the cooling jacket passage, thereby effectively cooling the stationary ring and the secondary seal.

[0014] Furthermore, in the present invention, preferably, the refrigerant circulation circuit is provided with a discharge valve for controlling the flow of refrigerant, and further comprises a temperature sensor for measuring the temperature of the mechanical seal, and a controller for controlling the opening and closing operation of the discharge valve. When the temperature measured by the temperature sensor is above a predetermined threshold temperature, the controller opens the discharge valve and allows the refrigerant to flow toward the mechanical seal. With the present invention configured in this way, when the temperature of the mechanical seal is low and cooling by refrigerant is not required, the operating load of the refrigerant circulation circuit can be reduced, thereby saving power. [Effects of the Invention]

[0015] According to the motor system of the present invention, the mechanical seal can be sufficiently cooled. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic 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 the refrigeration cycle of a motor system according to an embodiment of the present invention. [Figure 4] This is a cross-sectional view showing a mounting structure for 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 from the line VI-VI in Figure 5. [Figure 7] This is a partial cross-sectional view of a casing according to an embodiment of the present invention. [Figure 8] It is a flowchart showing the processing flow of a motor system according to an embodiment of the present invention. [Figure 9] It is a graph showing the relationship between the motor rotation speed and the temperature of the mechanical seal. [Figure 10] It 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] It is a partial cross-sectional view of an end cover according to a modified example of an embodiment of the present invention. [Figure 12] It is a cross-sectional view showing the mounting structure of a mechanical seal according to a modified example of an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0017] 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, referring to FIGS. 1 and 2, the overall configuration of the motor system S according to the present embodiment will be described. FIG. 1 is a schematic configuration diagram of the motor system according to the present embodiment, and FIG. 2 is an electrical block diagram of the motor system. The motor system S shown in FIG. 1 is configured to supply lubricating oil to a mechanical seal incorporated in a motor M used for driving a vehicle such as an electric vehicle, and to supply a refrigerant to the motor M (particularly, the stator and the rotor).

[0018] For this reason, the motor system S includes a refrigerant circulation circuit 60 for circulating the refrigerant R in the motor M to cool the motor M. In the present embodiment, the refrigerant R is a natural refrigerant such as, for example, a CO2 refrigerant. Further, the motor system S includes a lubricating oil circulation circuit 40 for circulating the lubricating oil L to the mechanical seal 30 and the bearing 14 to lubricate the mechanical seal 30 and the bearing 14.

[0019] The lubrication oil 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 lubrication oil L, a pump 43 for pumping the lubrication oil L from the tank 42, two switching valves 44a and 44b, a lubrication oil heat exchange section 45, an optional discharge valve 46, an optional regulator 47, and a motor M. Downstream of the regulator 47 is a lubrication oil temperature sensor 48 for measuring the lubrication oil temperature TL of the lubrication oil 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.

[0020] 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 lubricating oil 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 lubricating oil 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.

[0021] The lubrication oil heat exchange unit 45 is configured to cool the lubrication oil L by performing heat exchange between the refrigerant R flowing through the refrigerant circulation circuit 60 and the lubrication oil L. In other words, in the lubrication oil heat exchange unit 45, the lubrication oil L is cooled by the low-temperature refrigerant R by performing heat exchange between the lubrication oil L and the refrigerant R as they pass through separate pipes.

[0022] The discharge valve 46 is an on-off valve that opens and closes the flow path 41, switching between supplying and stopping the lubricating oil 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.

[0023] In the lubrication oil circulation circuit 40, lubricating oil L is supplied from the tank 42 by a pump 43 toward the downstream of the flow path 41. After passing through the first branch flow path 41a or the second branch flow path 41b, the lubricating oil L is supplied into the motor M and lubricates the mechanical seal 30 inside the motor M. The lubricating oil L that has lubricated the mechanical seal 30 returns to the tank 42 from the discharge section of the motor M through the discharge flow path 41c.

[0024] Furthermore, the flow path 41 has a branching flow path 41d downstream of the pump 43. The lubricating oil L flowing through the flow path 41d is supplied to the motor M bearing 14 without going to the switching valve 44a. The lubricating oil L that has lubricated the bearing 14, together with the lubricating oil L that has lubricated the mechanical seal 30, flows from the discharge section into the flow path 41c.

[0025] The refrigerant circulation circuit 60 is configured by sharing some components with the lubricating oil circulation circuit 40. The refrigerant circulation circuit 60 forms a refrigeration cycle using refrigerant R (CO2 refrigerant) and includes a tank 42 for storing lubricating oil L and refrigerant R, a compressor 63 for compressing refrigerant R, a heat exchanger (condenser) 64 including a condenser and fan, discharge valves 65a and 65c, an optional regulator 66, an expansion valve 67a (first expansion valve), an optional expansion valve 67b (second expansion valve), an expansion valve 67c (third expansion valve), a motor M as an evaporator, a lubricating oil heat exchange section 45, and a cooling jacket passage 25.

[0026] Tank 42 is configured to store both lubricating oil L and refrigerant R, and within tank 42, the liquid lubricating oil L and the gaseous refrigerant R (CO2 refrigerant) are separated into upper and lower parts. Therefore, the lubricating oil circulation circuit 40 can take out lubricating oil L from the lower part of tank 42, and the refrigerant circulation circuit 60 can take out refrigerant R from the upper part of tank 42.

[0027] In this embodiment, the flow path 61 includes a first flow path 61a, a second flow path 61b, and a third flow path 61c, which branch downstream of the heat exchanger 64 toward expansion valves 67a, 67b, and 67c, respectively. The first flow path 61a communicates with the internal space of the motor M and sprays the refrigerant R that has passed through the expansion valve 67a toward the rotor and stator to cool them. The third flow path 61c communicates with the cooling jacket passage 25 for the mechanical seal 30 and cools the mechanical seal 30 with the refrigerant R that has passed through the expansion valve 67c. The refrigerant R that has cooled the motor M and the mechanical seal 30 returns to the tank 42 from the discharge section of the motor M through the discharge flow path 41c, similar to the lubricating oil L.

[0028] Furthermore, the second flow path 61b passes through the expansion valve 67b and the lubrication oil heat exchange section 45 and merges with the flow path 61 between the tank 42 and the compressor 63. The refrigerant R that has passed through the expansion valve 67b exchanges heat with the lubrication oil L in the lubrication oil heat exchange section 45, cooling the lubrication oil L.

[0029] In this embodiment, the expansion valves 67a and 67b are electronically controlled expansion valves whose valve opening can be electronically controlled. Expansion valve 67a can be attached to the flow path 61 or the casing 20. On the other hand, expansion valve 67c is a pore provided in the casing 20. The refrigerant R expands as it flows through the pore into the internal space (seal arrangement space F) inside the motor M. However, expansion valve 67c may also be an electronically controlled expansion valve attached to the flow path 61 or the casing 20. Furthermore, expansion valve 67a may be integrated with the casing 20, in which case expansion valve 67a may be an electronically controlled expansion valve or a pore provided in the casing 20.

[0030] In this embodiment, an expansion valve 67b is provided, but the invention is not limited to this. By providing a first flow path 61a that branches off downstream of the expansion valve 67a and guides the refrigerant R to the lubricating oil heat exchange section 45, the expansion valve 67b may be omitted.

[0031] Furthermore, in this embodiment, the flow path 61 includes a fourth flow path 61d that branches off from the main flow path 61 downstream of the heat exchanger 64. The refrigerant R flowing through the fourth flow path 61d is reduced to a predetermined pressure by the regulator 66, and then merges with the lubricating oil L flowing through the flow path 41d, or is supplied separately to the bearing 14 of the motor M. If it is not necessary to cool the bearing 14 with the refrigerant R, the fourth flow path 61d and the regulator 66 may be omitted.

[0032] 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 valves 67a and 67c, cooling the components inside the motor M (especially the stator and rotor, and the mechanical seal 30). 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, similar to the lubricating oil L.

[0033] [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.

[0034] 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.

[0035] 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 lubricating oil 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 lubricating oil 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 lubricating oil L and refrigerant R to a discharge passage 41c.

[0036] 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, lubricating oil temperature, etc.) and outputs operation signals to each component of the lubricating oil 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.

[0037] [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.

[0038] 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).

[0039] 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).

[0040] Furthermore, an evaporation process (DA) takes place inside the motor M (or in the lubrication oil 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 lubrication oil L in the lubrication oil 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).

[0041] [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.

[0042] 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.

[0043] 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).

[0044] 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] Furthermore, the housing 21 has internal passages 20a formed at multiple locations in the circumferential direction, which serve as passages 41 for the lubricating oil circulation circuit 40 and guide the lubricating oil L to the seal placement space F. Also, the housing 21 has internal passages 22b formed at multiple locations in the circumferential direction, which serve as passages 61 for the refrigerant circulation circuit 60 and guide the refrigerant R to the seal placement space F. In addition, the housing 21 has multiple internal passages 22c 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 refrigerant R guided through the internal passages 22b. 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.

[0049] 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.

[0050] 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 22c 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.

[0051] 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).

[0052] In the example shown in Figure 4, internal passages 20a and 22b extending from top to bottom open into the seal placement space F through injection holes 20A and 20B, respectively, with tapered tips. Additionally, another internal passage 22c 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 holes 20A and 20B are configured to inject lubricating oil L and refrigerant R with predetermined directionality. The refrigerant R injection hole 20B functions as an expansion valve 67c. That is, the medium-temperature, high-pressure refrigerant R expands as it is blown out from the injection hole 20B into the seal placement space F, becoming a low-temperature, low-pressure refrigerant R. However, regardless of the presence or absence of the injection hole 20B, an expansion valve 67c, which is an electronic expansion valve, may be placed outside the seal placement space F, and the low-temperature, low-pressure refrigerant R output from the expansion valve 67c may be supplied through the internal passage 22b.

[0053] Lubricating oil L is directed by injection through the injection holes 20A via the internal passage 20a towards the mechanical seal 30 in the seal arrangement space F (particularly the sliding portion between the rotating ring 31 and the stationary ring 32), thereby lubricating the mechanical seal 30. Additionally, refrigerant R injected from the injection holes 20B via the internal passage 22b is injected in a spray pattern toward the opening of another internal passage 22c, and is guided through the internal passage 22c to the inlet passage 25a formed in the end cover 23.

[0054] The refrigerant R 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 internal flow path 22c from the outlet passage 25b. As shown in Figure 7, the injection hole 20A is positioned so as not to inject lubricating oil L toward the outlet passage 25b (and the internal flow path 22c communicating with the outlet passage 25b), and is set to have a directional injection pattern so as not to inject lubricating oil L toward the outlet passage 25b.

[0055] 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 22c is formed in the closing portion 21a. The other internal flow path 22c 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 22c.

[0056] 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.

[0057] [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.

[0058] 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.

[0059] 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 lubricating oil 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 lubricating oil L through the second branch passage 41b, keeps the discharge valve 46 open, and operates the regulator 47 to reduce the pressure of the lubricating oil L to a predetermined level.

[0060] 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.

[0061] 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.

[0062] 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 low-temperature refrigerant R is supplied to the cooling jacket passage 25, and lubricating oil L cooled in the lubricating oil heat exchange section 45 is injected onto the mechanical seal 30, thereby preventing the sealing temperature T of the mechanical seal 30 (especially the secondary seal 33) from reaching the heat resistance temperature Tr.

[0063] In the case of a negative determination in step S13 (S13; No), the controller 50 ends the process. That is, while the seal temperature T of the mechanical seal 30 is low, the refrigerant R is not provided to the cooling jacket passage 25, and the lubricating oil L is supplied to the mechanical seal 30 without being cooled by the lubricating oil heat exchanger 45. Thereby, the operating load of the compressor 63 or the like can be reduced to achieve power saving.

[0064] On the other hand, in the case of an affirmative determination in step S13 (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 lubricating oil L through the first branch passage 41a. Thereby, the lubricating oil L exchanges heat with the refrigerant R in the lubricating oil heat exchanger 45 and is cooled. Therefore, since the lubricating oil L cooled by the refrigerant R is supplied to the mechanical seal 30, the sliding portion of the mechanical seal 30 is cooled more efficiently, and the secondary seal 33 is suppressed from reaching the heat-resistant temperature Tr.

[0065] Furthermore, the controller 50 switches the valve position of the discharge valve 65c from the closed position to the open position (step S15), and supplies the low-temperature and low-pressure refrigerant R to the cooling jacket passage 25. Thereby, the mechanical seal 30 (particularly, the stationary ring 32 and the secondary seal 33) is effectively cooled, 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 position Ve of the discharge valve 65c of the refrigerant R is maintained at the closed position CL, and the valve positions Vs of the switching valves 44a and 44b are maintained at the bypass position Pb.

[0067] Furthermore, during another period of time t3 to t6, the rotor 11 rotates, and in conjunction with this, the valve opening Vd of the discharge valve 46 is maintained in the open position (OP). During this period, when the sealing temperature T of the mechanical seal 30 reaches the threshold temperature Tth at time t4, the valve position Ve of the refrigerant R discharge valve 65c is switched from the closed position CL to the open position OP, and 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, low-temperature refrigerant R is supplied to the cooling jacket passage 25 after time t4, and the lubricating oil L is cooled by the lubricating oil heat exchange section 45, causing the lubricating oil temperature TL to decrease. Consequently, when the sealing temperature T of the mechanical seal 30 falls below the threshold temperature Tth at time t5, the valve position Ve of the discharge valve 65c is switched back to the closed position CL, and the valve positions Vs of the switching valves 44a and 44b are switched back to the bypass position Pb.

[0068] [Modified example of a 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 refrigerant R injected from the injection hole 20B reaches the inlet passage 25a through another internal passage 22c and is discharged to the outside from the outlet passage 25b through another internal passage 22c below.

[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 internal passage 22b of the housing 21 is in direct communication with the cooling jacket passage 25 to supply lubricating oil L. In this embodiment, the internal passage 22b 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 the inlet passage 25a formed in the end cover 23. The internal passage 22b opens into the inlet passage 25a with an injection hole 20C that tapers to a narrowed tip. The injection hole 20C functions as an expansion valve 67c. That is, the medium-temperature, high-pressure refrigerant R expands when it is blown out from the injection hole 20C into the inlet passage 25a, becoming a low-temperature, low-pressure refrigerant R. As a result, in this embodiment, the mechanical seal 30 (especially the secondary seal 33) can be cooled more efficiently by directly supplying the refrigerant R to the cooling jacket passage 25. As described above, an electronic expansion valve 67c may be used regardless of the presence or absence of the injection hole 20C.

[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 with a predetermined pressure in the axial direction Y of the rotating shaft 13, and a refrigerant circulation circuit 60 that cools the motor M by circulating a refrigerant R through a refrigerant passage 61 passing through the motor M, wherein the refrigerant R is a CO2 refrigerant. The refrigerant circulation circuit 60 includes a tank 42 for storing refrigerant R, a compressor 63 for compressing the refrigerant R supplied from the tank 42, a heat exchanger 64 for dissipating heat from the compressed refrigerant R, and an expansion valve 67c for expanding the dissipated refrigerant R. The casing 20 has a cooling jacket passage 25 formed therein for allowing the refrigerant R to flow so as to pass near the stationary ring 32 and / or secondary seal 33, and the refrigerant flow path 61 is configured to guide at least the refrigerant R expanded by the expansion valve 67c into the cooling jacket passage 25.

[0071] In this embodiment, a cooling jacket passage 25 is formed in the casing 20 through which refrigerant R passes to cool the mechanical seal 30, and the casing 20 is configured to function as a cooling jacket. Furthermore, in this embodiment, the low-temperature, low-pressure refrigerant R expanded by the expansion valve 67c is guided 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 cooling jacket passage 25 includes an inlet passage 25a extending axially Y from the inner surface of the casing 20 to receive the refrigerant R, a cooling passage 25c communicating with the inlet passage 25a and extending around the rotating shaft 13 within the casing 20 to allow the refrigerant R to pass through, and an outlet passage 25b communicating with the cooling passage 25c to discharge the refrigerant R 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 refrigerant R 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.

[0073] Furthermore, according to this embodiment, the motor M has an oil supply unit 20A that sprays lubricating oil L onto the sliding part of the mechanical seal 30, and the outlet passage 25b opens in a position within the internal space F of the motor M surrounded by the casing 20 where the lubricating oil L from the oil supply unit 20A is not directly sprayed. In this embodiment configured in this way, the refrigerant R discharged from the outlet passage 25b is not obstructed by the lubricating oil L sprayed from the oil supply unit 20A, so the refrigerant R can flow efficiently through the cooling jacket passage 25.

[0074] Furthermore, according to this embodiment, the refrigerant flow path 61 communicates with the cooling jacket passage 25 via the arrangement space F in which the mechanical seal 30 is located within the casing 20. In this embodiment, the mechanical seal 30 can be cooled in the seal arrangement space F by the refrigerant R before the refrigerant R is supplied to the cooling jacket passage 25.

[0075] Furthermore, according to this embodiment, the refrigerant flow path 61 communicates with the cooling jacket passage 25 without passing through the arrangement space F in the casing 20 where the mechanical seal 30 is located. In this embodiment, the refrigerant R is efficiently supplied to the cooling jacket passage 25, thereby effectively cooling the stationary ring 32 and the secondary seal 33.

[0076] Furthermore, according to this embodiment, the refrigerant circulation circuit 60 is provided with a discharge valve 65c for controlling the flow of refrigerant R, and further comprises a temperature sensor 49 for measuring the temperature T of the mechanical seal 30, and a controller 50 for controlling the opening and closing operation of the discharge valve 65c. The controller 50 opens the discharge valve 65c and allows the refrigerant R to flow toward the mechanical seal 30 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 configured in this way, when the temperature T of the mechanical seal 30 is low and cooling by refrigerant R is not required, the operating load of the refrigerant circulation circuit 60 can be reduced, thereby saving power. [Explanation of Symbols]

[0077] 13 Rotation axis 20 Casing 20a Internal flow path 21 Housing 23 End cover 22b, 22c Internal flow path 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 Lubrication oil circulation circuit 41 Flow channels 46 Discharge valve 50 controllers 60 Refrigerant circulation circuit 61 Flow channels 65c Discharge valve 67c Expansion valve F Seal placement space L Lubricating Oil 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, The system includes a refrigerant circulation circuit that circulates a refrigerant through a refrigerant passage that passes through the motor to cool the motor, The aforementioned refrigerant is CO 2 It is a refrigerant, The refrigerant circulation circuit includes a tank for storing the refrigerant, 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. A motor system wherein the casing has a cooling jacket passage formed therein for allowing the refrigerant to flow so as to pass near the stationary ring and / or the secondary seal, and the refrigerant flow path is configured to guide the refrigerant, expanded by the expansion valve, to at least the cooling jacket passage.

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

3. The motor has an oil supply unit that sprays lubricating oil onto the sliding part of the mechanical seal. The motor system according to claim 2, wherein the outlet passage opens within the internal space of the motor enclosed by the casing, in a position where the lubricating oil from the oil supply unit is not directly sprayed onto it.

4. The motor system according to claim 1, wherein the refrigerant flow path communicates with the cooling jacket passage via the arrangement space in the casing where the mechanical seal is located.

5. The motor system according to claim 1, wherein the refrigerant flow path communicates with the cooling jacket passage without passing through the arrangement space in the casing where the mechanical seal is located.

6. The refrigerant circulation circuit is provided with a discharge valve for controlling the flow of the refrigerant. The system further includes a temperature sensor for measuring the temperature of the mechanical seal and a controller for controlling the opening and closing operation of the discharge valve. The motor system according to any one of claims 1 to 5, wherein the controller opens the discharge valve and directs the refrigerant toward the mechanical seal when the temperature measured by the temperature sensor is equal to or greater than a predetermined threshold temperature.

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