Power transmission devices and expansion valves

Abstract

This power transmission device comprises: a magnetic gear (60b) having an input axis magnet (20) to which rotational driving force is input, a magnetic modulation unit (25) for modulating magnetic fluxes, a multi-pole magnet (40) having a larger number of poles than that of the input axis magnet, and an output axis (41) that rotates integrally with the magnetic modulation unit or the multi-pole magnet; and a magnetic circuit (MC) in which the magnetic fluxes from the input axis magnet flow in parallel. The magnetic circuit forms: a torque generation path (φ1) in which the magnetic fluxes flow from the N-pole (20n) of the input axis magnet to the S-pole (20s) of the input axis magnet via the magnetic modulation unit and the multi-pole magnet, thereby generating torque; and a short-circuit magnetic flux path (φ2) in which the magnetic fluxes flow from the N-pole of the input axis magnet to the S-pole of the input axis magnet in a short-circuit manner without via the magnetic modulation unit.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Patent Application No. 2022-103445 filed on June 28, 2022, the contents of which are incorporated herein by reference. [Technical Field]

[0002] The present disclosure relates to a power transmission device having a magnetic gear that transmits power using magnetic force, and an expansion valve including the same. [Background technology]

[0003] A conventional power transmission device of this type is described in Patent Document 1. This conventional technology includes cylindrical first and second movers arranged coaxially with each other, and a cylindrical intermediate yoke arranged between the first and second movers.

[0004] The first and second movers have a predetermined number of magnetic pole pairs arranged along the circumferential direction. The intermediate yoke has a plurality of magnetic bodies arranged along the circumferential direction. The number of magnetic bodies in the intermediate yoke is the same as the total number of magnetic pole pairs in the first mover and the second mover.

[0005] When one of the first and second movers rotates, the other mover rotates due to magnetic interaction between the magnetic pole pairs of the first mover and the second mover. In other words, torque is generated between the first and second movers and the intermediate yoke, transmitting power. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5958466 Summary of the Invention

[0007] In a power transmission device having a magnetic gear such as the above-mentioned conventional technology, it is desirable to maximize the transmission torque by effectively utilizing the magnetic forces of the first and second movers.

[0008] In view of the above, an object of the present disclosure is to improve transmission torque in a power transmission device having a magnetic gear and an expansion valve including the same.

[0009] The present disclosure 1st The power transmission device according to the present invention includes a magnetic gear and a magnetic circuit. A short-circuit magnetic flux forming member The magnetic gear includes an input shaft magnet, a magnetic modulation portion, a multi-pole magnet, and an output shaft.

[0010] A rotational driving force is input to the input shaft magnet. The magnetic modulation unit modulates the magnetic flux. The multi-pole magnet has more poles than the input shaft magnet. The output shaft rotates integrally with the magnetic modulation unit or the multi-pole magnet.

[0011] In the magnetic circuit, magnetic flux from the input shaft magnet flows in parallel. The magnetic circuit forms a torque generation path and a short-circuit magnetic flux path. In the torque generation path, magnetic flux flows from the north pole of the input shaft magnet via the magnetic modulation unit and multi-pole magnet to the south pole of the input shaft magnet, generating torque. In the short-circuit magnetic flux path, magnetic flux flows from the north pole of the input shaft magnet, short-circuiting to the south pole of the input shaft magnet without passing through the magnetic modulation unit. The short-circuit magnetic flux forming member is disposed between the input shaft magnet and the magnetic modulation unit, and has a magnetic permeability higher than that of a vacuum to form a short-circuit magnetic flux path. The permeability of the short-circuit magnetic flux forming member differs by ±20% from the permeability at which torque is maximized.

[0012] According to this, by forming a short-circuited magnetic flux path, it is possible to increase the magnetic flux flowing through the torque generating path, thereby improving the transmitted torque. 。

[0013] A power transmission device according to a second aspect of the present disclosure includes a magnetic gear, a magnetic circuit, and a short-circuit magnetic flux generating member. The magnetic gear includes an input shaft magnet, a magnetic modulation unit, a multi-pole magnet, and an output shaft. Magnetic flux from the input shaft magnet flows in parallel through the magnetic circuit. The magnetic circuit forms a torque generation path and a short-circuit magnetic flux path. In the torque generation path, magnetic flux flows from the north pole of the input shaft magnet via the magnetic modulation unit and the multi-pole magnet to the south pole of the input shaft magnet, generating torque. In the short-circuit magnetic flux path, magnetic flux flows from the north pole of the input shaft magnet to the south pole of the input shaft magnet, bypassing the magnetic modulation unit. The short-circuit magnetic flux generating member is disposed between the input shaft magnet and the magnetic modulation unit and has a magnetic permeability higher than that of a vacuum, forming the short-circuit magnetic flux path. The magnetic permeability of the short-circuit magnetic flux generating member is within ±10% of the magnetic permeability at which torque is maximized. This allows for the same effects as those of the first aspect.

[0014] A power transmission device according to a third aspect of the present disclosure includes a magnetic gear, a magnetic circuit, and a short-circuit magnetic flux forming member. The magnetic gear includes an input shaft magnet, a magnetic modulation unit, a multi-pole magnet, and an output shaft. Magnetic flux from the input shaft magnet flows in parallel in the magnetic circuit. The magnetic circuit forms a torque generation path and a short-circuit magnetic flux path. In the torque generation path, magnetic flux flows from the north pole of the input shaft magnet via the magnetic modulation unit and the multi-pole magnet to the south pole of the input shaft magnet, generating torque. In the short-circuit magnetic flux path, magnetic flux flows from the north pole of the input shaft magnet to the south pole of the input shaft magnet, bypassing the magnetic modulation unit. The short-circuit magnetic flux forming member is disposed between the input shaft magnet and the magnetic modulation unit and has a magnetic permeability higher than that of a vacuum, forming the short-circuit magnetic flux path. The short-circuit magnetic flux forming member is made of austenitic stainless steel and contains martensite. This allows for the same effects as those of the first aspect.

[0015] A power transmission device according to a fourth aspect of the present disclosure includes a magnetic gear, a magnetic circuit, and a short-circuit magnetic flux forming member. The magnetic gear has an input shaft magnet, a magnetic modulation unit, a multi-pole magnet, and an output shaft. Magnetic flux from the input shaft magnet flows in parallel in the magnetic circuit. The magnetic circuit forms a torque generation path and a short-circuit magnetic flux path. In the torque generation path, magnetic flux flows from the north pole of the input shaft magnet via the magnetic modulation unit and the multi-pole magnet to the south pole of the input shaft magnet, generating torque. In the short-circuit magnetic flux path, magnetic flux flows from the north pole of the input shaft magnet to the south pole of the input shaft magnet, short-circuiting it without passing through the magnetic modulation unit. The short-circuit magnetic flux forming member is disposed between the input shaft magnet and the magnetic modulation unit and forms the short-circuit magnetic flux path, having a magnetic permeability higher than that of a vacuum. The short-circuit magnetic flux forming member is a partition wall that separates the drive-side space, which is the space on the input shaft magnet side, from the driven-side space, which is the space on the magnetic modulation unit side. The short-circuit magnetic flux generating member forms part of a pressure vessel that seals the driven-side space so as to have pressure resistance, thereby achieving the same effects as those of the first aspect. [Brief explanation of the drawings]

[0017] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. [Figure 1] 1 is an overall configuration diagram of a vehicle air conditioner according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of a first expansion valve of the first embodiment. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. [Figure 4] 1 is a block diagram showing an electronic control unit of a vehicle air conditioner according to a first embodiment. [Figure 5] FIG. 2 is a circuit diagram showing a magnetic circuit formed by the magnetic gear of the first embodiment. [Figure 6] 4 is a graph showing the relationship between magnetic permeability and transmission torque in the magnetic gear of the first embodiment. [Figure 7] FIG. 10 is a cross-sectional view of a magnetic gear according to a second embodiment. [Figure 8] FIG. 10 is an exploded perspective view of a magnetic gear according to a third embodiment. [Figure 9] FIG. 10 is a cross-sectional view schematically showing a magnetic gear according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] Hereinafter, several embodiments for carrying out the present disclosure will be described with reference to the drawings. In each embodiment, parts corresponding to matters described in the preceding embodiment will be assigned the same reference numerals, and duplicated explanations may be omitted. In each embodiment, when only a part of the configuration is described, other previously described embodiments may be applied to the other parts of the configuration. In addition to combinations of parts that are specifically specified as being combinable in each embodiment, it is also possible to partially combine embodiments even if not specified, as long as there is no particular problem with the combination.

[0019] A first embodiment of the present disclosure will be described with reference to Figures 1 to 7. A power transmission device 1 of this embodiment is applied to a first expansion valve 113 and a second expansion valve 115 of a vapor compression refrigeration cycle 110. The vapor compression refrigeration cycle 110 is applied to a vehicle air conditioner 100 shown in Figure 1. The vehicle air conditioner 100 is applied to an electric vehicle that obtains driving power for running the vehicle from an electric motor for running the vehicle.

[0020] The vehicle air conditioner 100 has three operating modes: a cooling mode for cooling the vehicle interior, a heating mode for heating the vehicle interior, and a dehumidifying and heating mode for heating and dehumidifying the vehicle interior. In Fig. 1, the refrigerant flow in the cooling mode is indicated by a solid arrow, the refrigerant flow in the heating mode is indicated by a dashed arrow, and the refrigerant flow in the dehumidifying and heating mode is indicated by a two-dot chain arrow.

[0021] The vehicle air conditioner 100 includes a vapor compression refrigeration cycle 110 and a vehicle interior air conditioning unit 120 .

[0022] The vapor compression refrigeration cycle 110 has a compressor 111 , an indoor heat exchanger 112 , a first expansion valve 113 , an outdoor heat exchanger 114 , a second expansion valve 115 , an evaporator 116 , an electromagnetic on-off valve 117 , and an accumulator 118 .

[0023] The compressor 111 is an electric compressor that draws in, compresses, and discharges a refrigerant. The vapor compression refrigeration cycle 110 is a subcritical cycle in which the high-pressure side refrigerant pressure does not exceed the critical pressure of the refrigerant, and a fluorocarbon refrigerant (e.g., R134a) is used as the refrigerant circulating through the vapor compression refrigeration cycle 110.

[0024] The indoor heat exchanger 112 condenses the refrigerant discharged from the compressor 111 by exchanging heat with the air flowing inside the vehicle interior air conditioning unit 120. The first expansion valve 113 decompresses and expands the refrigerant condensed in the indoor heat exchanger 112. The outdoor heat exchanger 114 exchanges heat between the refrigerant flowing out from the first expansion valve 113 and outside air.

[0025] The second expansion valve 115 reduces the pressure and expands the refrigerant that has flowed out from the exterior heat exchanger 114. The evaporator 116 evaporates the refrigerant that has been reduced in pressure and expanded by the second expansion valve 115 by exchanging heat with the air flowing inside the interior air conditioning unit 120.

[0026] The electromagnetic on-off valve 117 is a solenoid valve that opens and closes a refrigerant flow path that leads the refrigerant flowing out from the outdoor heat exchanger 114 to the accumulator 118, bypassing the second expansion valve 115 and the evaporator 116. The accumulator 118 separates the refrigerant evaporated in the evaporator 116 and the refrigerant that has passed through the electromagnetic on-off valve 117 into gas and liquid.

[0027] The vehicle interior air conditioning unit 120 is disposed in the vehicle interior and forms an air passage therein. In the air passage in the vehicle interior air conditioning unit 120, a blower 121, an evaporator 116, an interior heat exchanger 112, and an air mix door 122 are disposed.

[0028] The blower 121 is an electric blower that blows air into an air passage in the vehicle interior air conditioning unit 120. The evaporator 116 is arranged downstream of the blower 121 in the air flow. The interior heat exchanger 112 is arranged downstream of the evaporator 116 in the air flow. The air mix door 122 adjusts the flow rate ratio between the air flowing to the interior heat exchanger 112 and the air flowing bypassing the interior heat exchanger 112. The vehicle interior air conditioning unit 120 blows air whose temperature has been adjusted by the air mix door 122 into the vehicle interior.

[0029] In the cooling mode of the vehicle air conditioner 100, the electromagnetic on-off valve 117 is closed, and the air mix door 122 closes the air flow path to the indoor heat exchanger 112. Therefore, the refrigerant discharged from the compressor 111 passes through the indoor heat exchanger 112 without undergoing heat exchange therein, flows through the first expansion valve 113, the outdoor heat exchanger 114, the second expansion valve 115, the evaporator 116, and the accumulator 118 in this order, and returns from the accumulator 118 to the compressor 111.

[0030] At this time, the first expansion valve 113 is fully opened so as not to throttle the refrigerant flow, and the second expansion valve 115 is opened to throttle the refrigerant flow, so that the refrigerant is condensed in the outdoor heat exchanger 114 and evaporated in the evaporator 116.

[0031] In the heating mode of the vehicle air conditioner 100, the electromagnetic on-off valve 117 is opened, the second expansion valve 115 is closed to block the flow of refrigerant, and the air mix door 122 is opened to allow air to flow to the indoor heat exchanger 112. Therefore, the refrigerant discharged from the compressor 111 flows sequentially through the indoor heat exchanger 112, the first expansion valve 113, the outdoor heat exchanger 114, the electromagnetic on-off valve 117, and the accumulator 118, and then returns from the accumulator 118 to the compressor 111. At this time, the first expansion valve 113 is opened to a degree that throttles the refrigerant flow, and the second expansion valve 115 is closed, so that the refrigerant is condensed in the indoor heat exchanger 112, evaporated in the outdoor heat exchanger 114, and does not flow to the evaporator 116.

[0032] In the dehumidifying and heating mode of the vehicle air conditioner 100, the electromagnetic on-off valve 117 is closed, and the air mix door 122 is opened to allow air to flow to the indoor heat exchanger 112. Therefore, the refrigerant discharged from the compressor 111 flows in this order through the indoor heat exchanger 112, the first expansion valve 113, the outdoor heat exchanger 114, the second expansion valve 115, the evaporator 116, and the accumulator 118, and then returns to the compressor 111 from the accumulator 118.

[0033] At this time, the first expansion valve 113 and the second expansion valve 115 are opened to a degree that restricts the flow of refrigerant, so that the refrigerant is condensed in the indoor heat exchanger 112 and evaporated in the outdoor heat exchanger 114 and the evaporator 116.

[0034] 2, the first expansion valve 113 has the power transmission device 1, the drive-side mechanism unit 10, and the driven-side mechanism unit 35. The first expansion valve 113 is disposed longitudinally in the vehicle. The longitudinal disposition means that the axial direction of the valve body 48 is approximately parallel to the vertical direction of the vehicle, and the drive-side mechanism unit 10 is disposed above the driven-side mechanism unit 35.

[0035] The power transmission device 1 transmits the rotational driving force generated by the drive-side mechanism portion 10 to the driven-side mechanism portion 35 using magnetic force.

[0036] The drive-side mechanism section 10 has a motor section 11 and a motor case 15. The motor section 11 is a motor that can be driven by speed feedback control, and has a stator 12, a rotor 13, and a shaft 14. The motor section 11 is, for example, a three-phase brushless motor or a DC brush motor.

[0037] The shaft 14 is the output shaft of the motor unit 11 and also the input shaft of the power transmission device 1, and rotates integrally with the rotor 13. The motor case 15 houses the motor unit 11.

[0038] The stator 12 is fixed to a motor case 15. The stator 12 has a stator coil 12a. In this example, the number of slots Ns of the stator 12 is six.

[0039] The rotor 13 is cylindrical, and the stator 12 is disposed inside the rotor 13. As shown in Fig. 3, the rotor 13 has multiple pairs of magnets, each consisting of an N pole 13n and an S pole 13s, arranged along the circumferential direction. In this example, there are four N poles 13n and four S poles 13s, so the number of poles Pr of the rotor 13 is eight. The stator 12 and the rotor 13 output a driving force that rotates the shaft 14 by electromagnetic force.

[0040] The motor case 15 is formed with an axis alignment portion 15a for axial alignment (so-called centering) between the shaft 14 of the drive-side mechanism portion 10 and the rotating member 41 of the driven-side mechanism portion 35. The axis alignment portion 15a is fitted into the main body portion 50 of the driven-side mechanism portion 35.

[0041] A circuit section 70 is housed within the motor case 15. The circuit section 70 has a circuit board on which a plurality of electronic components for controlling the motor section 11 are mounted.

[0042] The driven side mechanism portion 35 has a rotating member 41, a valve body 48, a bearing member 49, and a main body portion 50.

[0043] The rotating member 41, the valve element 48, and the bearing member 49 are housed in a main body 50. The main body 50, together with the motor case 15, constitutes the housing of the first expansion valve 113. The main body 50 is formed with a valve chamber 52, an inlet-side connection port 53, an outlet-side connection port 54, and a valve seat 55. The main body 50 is a valve port forming member that forms the valve port 52a of the valve chamber 52.

[0044] The rotating member 41 is the output shaft of the power transmission device 1, and is rotated by the driving force transmitted from the drive-side mechanism 10. The rotating member 41 is a rod-shaped member, and is arranged coaxially with the shaft 14. An engagement groove 41a is formed at the end of the rotating member 41 opposite the drive-side mechanism 10. The rotating member 41 is rotatably supported by a bearing member 49 fixed to the main body 50.

[0045] The valve element 48 is a rod-shaped member disposed within the valve chamber 52. The valve element 48 is disposed coaxially with the rotating member 41. A protruding piece 48a of the valve element 48 meshes with the meshing groove 41a of the rotating member 41. As a result, the rotational force of the rotating member 41 is transmitted to the valve element 48.

[0046] The protruding piece 48a is formed at one end of the valve body 48. A male screw is formed on the outer peripheral surface of the valve body 48. The male screw of the valve body 48 is threaded into a screw hole 50a formed in the main body 50 to form a screw mechanism. As a result, when the valve body 48 rotates, the valve body 48 moves in the axial direction.

[0047] The valve element 48 is formed of a plurality of members. Specifically, the valve element 48 is composed of a male thread member 481 located on the rotating member 41 side and having the male thread formed thereon, a valve seat side member 482 located on the valve seat 55 side, and a ball 483 disposed between the two members 481 and 482. By disposing the ball 483 between the two members 481 and 482, the valve seat side member 482 of the valve element 48 moves in the axial direction without rotating.

[0048] A valve seat side member 482 of the valve body 48, which serves as a ball receiving member, is biased by a coil spring 47 in a direction away from the valve seat 55 in the axial direction of the valve body 48.

[0049] As the valve element 48 moves in the axial direction, the valve element 48 comes into contact with or separates from the valve seat 55, thereby opening and closing the valve port 52a of the valve chamber 52. When the valve element 48 separates from the valve seat 55 in the valve chamber 52, the refrigerant flows through the valve port 52a from the inlet-side connection port 53 to the outlet-side connection port 54, where it is decompressed and expanded.

[0050] The power transmission device 1 includes a non-contact coupling portion 60. The non-contact coupling portion 60 includes a magnetic gear 60b and a partition wall 51. The magnetic gear 60b includes a drive-side magnet 20, a pole piece 25, and a fixed magnet 40.

[0051] The drive-side magnet 20 is an input shaft magnet that rotates integrally with the shaft 14 of the motor unit 11. The pole piece 25 is a magnetic modulation unit that modulates magnetic flux between the drive-side magnet 20 and the fixed magnet 40, and rotates integrally with the rotating member 41. The fixed magnet 40 is fixed to the main body 50 of the first expansion valve 113.

[0052] The driving-side magnet 20 is cylindrical and is joined to the outer peripheral surface of the rotor 13 of the motor unit 11 via a cylindrical intervening member 21. In other words, the motor unit 11 is disposed inside the driving-side magnet 20. The intervening member 21 is made of a magnetic material.

[0053] The driving-side magnet 20 has at least one pair of magnets, each consisting of an N pole 20n and an S pole 20s, arranged along the circumferential direction. In this example, there is one N pole 20n and one S pole 20s, so the number of poles Pin of the driving-side magnet 20 is two.

[0054] The number of poles Pin of the drive-side magnet 20 is equal to the number of poles Pr of the rotor 13 minus the number of slots Ns of the stator 12. In this example, the number of poles Pr of the rotor 13 is 8, and the number of slots Ns of the stator 12 is 6, so the number of poles Pin of the drive-side magnet 20 is 2.

[0055] The partition wall 51 is a sealing member that divides the internal space of the first expansion valve 113 into a driving-side space 113a and a driven-side space 113b, and seals the driven-side space 113b. The driving-side space 113a is a space on the driving-side mechanism unit 10 side, and the driven-side space 113b is a space on the driven-side mechanism unit 35 side.

[0056] The partition wall 51 prevents the refrigerant (high-pressure refrigerant) present in the driven-side space 113b from leaking into the drive-side space 113a. In this example, the partition wall 51 is a member having a predetermined magnetic permeability. For example, the partition wall 51 is made of stainless steel that has been imparted with magnetism by transforming austenitic stainless steel such as SUS305 into martensite through work hardening.

[0057] The partition wall 51 is connected to the main body 50. The partition wall 51 and the main body 50 form a pressure vessel having pressure resistance.

[0058] The partition wall 51 is disk-shaped with a central portion recessed downward, and has a sealing upper surface portion 51a, a sealing cylindrical portion 51b, and a sealing bottom surface portion 51c. The sealing upper surface portion 51a is annular plate-shaped, and its outer edge is fixed to the main body portion 50 of the first expansion valve 113. The sealing cylindrical portion 51b is cylindrical and is located on the outer diameter side of the drive-side magnet 20. The sealing bottom surface portion 51c is located below the drive-side magnet 20 and blocks the sealing cylindrical portion 51b from the drive-side space 113a side.

[0059] The sealing bottom surface portion 51c is a disk-shaped portion whose center is curved downward. The corners forming the boundary between the sealing cylindrical portion 51b and the sealing bottom surface portion 51c are not right angles but are rounded with a predetermined radius of curvature, thereby improving pressure resistance.

[0060] In order to improve pressure resistance, the partition wall 51 has a sealing upper surface portion 51a, a sealing cylindrical portion 51b, and a sealing bottom surface portion 51c integrally molded.

[0061] The sealing bottom surface portion 51c is disposed in the gap between the shaft 14 and the rotating member 41 in the axial direction of the shaft 14 and the rotating member 41. That is, the sealing bottom surface portion 51c is disposed in a location where there are few torque generation points, which makes it easy to ensure that the partition wall 51 has torque resistance and pressure resistance.

[0062] The pole piece 25 is cylindrical, and is disposed on the outer diameter side of the sealed cylindrical portion 51b of the partition wall 51. The pole piece 25 is joined to the rotating member 41 of the driven-side mechanism portion .

[0063] The fixed magnet 40 is cylindrical and is disposed on the outer diameter side of the pole piece 25. The fixed magnet 40 is fitted into a cylindrical main body cylindrical portion 50b (in other words, the cylindrical portion of the housing) of the main body portion 50 (in other words, the housing) via a cylindrical back yoke 56. The back yoke 56 and the main body cylindrical portion 50b are formed of a magnetic material.

[0064] The fixed magnet 40 is a multi-pole magnet with a greater number of pairs of magnets, each consisting of an N pole 40n and an S pole 40s, arranged at approximately equal intervals along the circumferential direction. The number of poles Pf of the fixed magnet 40 is greater than the number of poles Pin of the drive-side magnet 20. In this example, there are 20 N poles 40n and 20 S poles 40s, so the number of poles Pf of the fixed magnet 40 is 40. The fixed magnet 40 is a multi-pole magnet with a greater number of poles than the drive-side magnet 20.

[0065] The pole piece 25 has a plurality of magnetic material portions 25a and a plurality of non-magnetic material portions 25b. The magnetic material portions 25a and the non-magnetic material portions 25b are frustum-shaped, and the magnetic material portions 25a are arranged at approximately equal intervals along the circumferential direction. The non-magnetic material portions 25b are arranged between the magnetic material portions 25a. For example, the magnetic material portions 25a are made of a soft magnetic material (e.g., an iron-based metal), and the non-magnetic material portions 25b are made of a non-magnetic material (e.g., stainless steel or resin).

[0066] The number of poles Pp of the pole piece 25 is the same as the sum of the number of poles Pin of the drive-side magnet 20 and the number of poles Pf of the fixed magnet 40. In this example, the number of poles Pin of the drive-side magnet 20 is 2, and the number of poles Pf of the fixed magnet 40 is 40, so the number of poles Pp of the pole piece 25 is 42. That is, there are 21 magnetic material portions 25a and 21 non-magnetic material portions 25b. That is, the number Npp of magnetic material portions 25a has the following relationship with the number of poles Pin of the drive-side magnet 20 and the number of poles Pf of the fixed magnet 40: Npp=(Pin+Pf) / 2 The axial length of the pole piece 25 is shorter than the axial length of the fixed magnet 40. This reduces axial magnetic flux leakage at the pole piece 25, improving transmission torque.

[0067] The configuration of the second expansion valve 115 is similar to that of the first expansion valve 113, and therefore a detailed description of the configuration of the second expansion valve 115 will be omitted.

[0068] Next, an overview of the electrical control unit of this embodiment will be described. The air conditioning control device 80, first expansion valve control device 81, and second expansion valve control device 82 shown in Fig. 4 are electronic control units having a well-known microcomputer including a CPU, ROM, RAM, etc., and peripheral circuits. The air conditioning control device 80, first expansion valve control device 81, and second expansion valve control device 82 perform various calculations and processes based on control programs stored in the ROM, and control the operation of various controlled devices connected to the output side.

[0069] The first expansion valve control device 81 and the second expansion valve control device 82 are connected to the air conditioning control device 80 via a harness so that they can communicate with each other. Therefore, based on a detection signal or an operation signal input to one of the control devices, the operation of a controlled device connected to the output side of the other control device can be controlled.

[0070] The air conditioning control device 80 controls the operation of the compressor 111 of the vapor compression refrigeration cycle 110, the electromagnetic on-off valve 117, the blower 121 of the vehicle interior air conditioning unit 120, the actuator for driving the air mix door 122, and the like.

[0071] The first expansion valve control device 81 controls the operation of the first expansion valve 113 of the refrigeration cycle 110. Specifically, it calculates the value of the drive current to be output to the motor unit 11 of the first expansion valve control device 81, and outputs the drive current to the motor unit 11 based on the calculation result. The first expansion valve control device 81 is composed of the circuit unit 70 of the first expansion valve 113.

[0072] The second expansion valve control device 82 controls the operation of the second expansion valve 115 of the vapor compression refrigeration cycle 110. Specifically, the second expansion valve control device 82 calculates the value of the drive current to be output to the motor unit 11 of the second expansion valve control device 82, and outputs the drive current to the motor unit 11 based on the calculation result. The second expansion valve control device 82 is composed of the circuit unit 70 of the second expansion valve 115.

[0073] A group of control sensors, such as an inside air temperature sensor 83, an outside air temperature sensor 84, a solar radiation sensor 85, an air conditioning air temperature sensor 86, a high-pressure side refrigerant sensor 87, and a low-pressure side refrigerant sensor 88, are connected to the input side of the air conditioning control device 80. Detection signals from these sensors are input to the air conditioning control device 80. These sensors are included in the components that make up the refrigeration cycle.

[0074] The interior air temperature sensor 83 is an interior air temperature detection unit that detects the interior air temperature Tr, which is the temperature inside the vehicle cabin. The exterior air temperature sensor 84 is an exterior air temperature detection unit that detects the exterior air temperature Tam, which is the temperature outside the vehicle cabin. The solar radiation sensor 85 is an solar radiation amount detection unit that detects the amount of solar radiation As irradiated into the vehicle cabin. The air conditioning air temperature sensor 86 is an air conditioning air temperature detection unit that detects the temperature TAV of the conditioned air blown into the vehicle cabin from the interior air conditioning unit 120.

[0075] The high-pressure side refrigerant sensor 87 is a high-pressure side refrigerant detection unit that detects the pressure and temperature of the high-pressure side refrigerant of the vapor compression refrigeration cycle 110. The low-pressure side refrigerant sensor 88 is a low-pressure side refrigerant detection unit that detects the pressure and temperature of the low-pressure side refrigerant of the vapor compression refrigeration cycle 110.

[0076] The input side of the air conditioning control device 80 is also connected to various operation switches provided on the air conditioning operation panel. The air conditioning operation panel is located near the instrument panel at the front of the vehicle interior. The instrument panel is located near the front of the vehicle interior directly in front of the driver's seat. The instrument panel displays various information such as the electric vehicle's traveling speed and operating status. If an abnormality or failure occurs in any of the electric vehicle's equipment, the instrument panel will warn the occupants by display, audio, etc.

[0077] Operation signals from various operation switches on the air conditioning operation panel are input to the air conditioning control device 80. Specific examples of the various operation switches provided on the air conditioning operation panel include an auto switch, an air conditioner switch, an air volume setting switch, and a temperature setting switch.

[0078] The auto switch is an operation unit that allows the occupant to activate or deactivate automatic control operation of the cabin air conditioning. The air conditioning switch is an operation unit that allows the occupant to request air cooling by the cabin evaporator. The air volume setting switch is an operation unit that allows the occupant to manually set the air volume of the blower 121. The temperature setting switch is an operation unit that allows the occupant to set the set temperature Tset in the cabin.

[0079] A first current / voltage sensor 90 and a first rotation angle sensor 91 are connected to the input side of the first expansion valve control device 81. The first current / voltage sensor 90 is a first expansion valve current / voltage detection unit that detects the current and voltage supplied to the motor unit 11 of the first expansion valve 113. The first rotation angle sensor 91 is a first rotation angle detection unit that detects the rotation angle (in other words, the rotation position) of the motor unit 11 of the first expansion valve 113.

[0080] The first current / voltage sensor 90 is attached to the first expansion valve 113. In the first current / voltage sensor 90, the current detection section and the voltage detection section are integrated, but the current detection section and the voltage detection section may also be configured as separate sections.

[0081] A second current / voltage sensor 92 and a second rotation angle sensor 93 are connected to the input side of the second expansion valve control device 82. The second current / voltage sensor 92 is a second expansion valve current / voltage detection unit that detects the current and voltage supplied to the motor unit 11 of the second expansion valve 115. The second rotation angle sensor 93 is a second rotation angle detection unit that detects the rotation angle (in other words, the rotation position) of the motor unit 11 of the second expansion valve 115.

[0082] The second current / voltage sensor 92 is attached to the second expansion valve 115. In the second current / voltage sensor 92, the current detection section and the voltage detection section are integrated, but the current detection section and the voltage detection section may be configured as separate sections.

[0083] Next, an outline of the operation of the vehicle air conditioner 100 in this embodiment will be described. The air conditioning control device 80 determines which operating mode to execute among the cooling mode, heating mode, and dehumidifying heating mode based on detection signals from a group of control sensors, such as an inside air temperature sensor 83, an outside air temperature sensor 84, a solar radiation sensor 85, an air conditioning air temperature sensor 86, a high-pressure side refrigerant sensor 87, and a low-pressure side refrigerant sensor 88.

[0084] The air conditioning control device 80 controls the opening and closing of the electromagnetic on-off valve 117, the first expansion valve 113, and the second expansion valve 115, and switches to the determined operation mode.

[0085] In the cooling mode, the solenoid on-off valve 117 is closed, the first expansion valve 113 is fully open so as not to throttle the refrigerant flow, and the second expansion valve 115 is opened to throttle the refrigerant flow. At this time, the air conditioning control device 80 determines a target throttle opening for the second expansion valve 115 based on detection signals from the control sensors and outputs the determined target throttle opening to the second expansion valve control device 82. The second expansion valve control device 82 controls the second expansion valve 115 so that the opening of the second expansion valve 115 becomes the target throttle opening output from the air conditioning control device 80.

[0086] In the heating mode, the solenoid on-off valve 117 is opened, the first expansion valve 113 is opened to throttle the flow of refrigerant, and the second expansion valve 115 is closed to block the flow of refrigerant. At this time, the air conditioning control device 80 determines a target throttle opening for the first expansion valve 113 based on detection signals from the control sensors and outputs the determined target throttle opening to the first expansion valve control device 81. The first expansion valve control device 81 controls the first expansion valve 113 so that the opening of the first expansion valve 113 becomes the target throttle opening output from the air conditioning control device 80.

[0087] In the dehumidifying heating mode, the solenoid on-off valve 117 is closed, and the first expansion valve 113 and the second expansion valve 115 are set to valve openings that throttle the flow of refrigerant. At this time, the air conditioning control device 80 determines the target throttle openings of the first expansion valve 113 and the second expansion valve 115 based on detection signals from the control sensors, and outputs the determined target throttle openings to the first expansion valve control device 81 and the second expansion valve control device 82. The first expansion valve control device 81 controls the first expansion valve 113 so that the opening of the first expansion valve 113 becomes the target throttle opening output from the air conditioning control device 80. The second expansion valve control device 82 controls the second expansion valve 115 so that the opening of the second expansion valve 115 becomes the target throttle opening output from the air conditioning control device 80.

[0088] Next, a description will be given of the operation of the first expansion valve 113 in this embodiment. The operation of the second expansion valve 115 is similar to that of the first expansion valve 113, so a description of the operation of the second expansion valve 115 will be omitted.

[0089] When a drive current is output from the first expansion valve control device 81 to the motor unit 11 of the first expansion valve 113, the rotor 13 of the motor unit 11 rotates, and the shaft 14 of the motor unit 11 also rotates integrally. When the shaft 14 of the motor unit 11 rotates and the drive-side magnet 20 also rotates integrally, the magnetic interaction between the drive-side magnet 20 and the fixed magnet 40 causes the pole piece 25 to rotate in the same direction as the rotation of the drive-side magnet 20.

[0090] The reduction ratio at this time is equal to the value obtained by dividing the number of poles Pp of the pole piece 25 by the number of poles Pin of the drive-side magnet 20. Since the number of poles Pp of the pole piece 25 is greater than the number of poles Pin of the drive-side magnet 20, the rotation speed of the pole piece 25 is smaller than the rotation speed of the drive-side magnet 20.

[0091] In this example, the number of poles Pp of the pole piece 25 is 42, and the number of poles Pin of the drive-side magnet 20 is 2, so the reduction ratio is 21.

[0092] In contrast, in a configuration in which the pole piece 25 is fixed and a magnet with the same number of poles as the fixed magnet 40 is joined to the rotating member 41 of the driven side mechanism part 35 and rotated (hereinafter, this configuration will be referred to as the comparative example), the reduction ratio is 20.

[0093] Since the number of poles Pp of the pole piece 25 is greater than the number of poles Pf of the fixed magnet 40, in this embodiment in which the pole piece 25 is rotated, the reduction ratio is greater than in the comparative example in which a magnet with the same number of poles as the fixed magnet 40 is rotated.

[0094] In this embodiment in which the pole piece 25 is rotated, the pole piece 25 is a member independent from the partition wall 51. Therefore, the pressure resistance of the partition wall 51 can be improved compared to the conventional structure in which the pole piece does not rotate and is embedded in the sealing plate.

[0095] The partition wall 51 has a cylindrical sealing portion 51b and a bottom sealing portion 51c, and thus has a disk-like shape with a central portion recessed toward the driven-side mechanism portion 35. Therefore, the partition wall 51 can be disposed as a member independent from the pole piece 25, and the pressure resistance of the partition wall 51 can be improved.

[0096] The number Npp of magnetic material portions 25a of the pole piece 25 has the following relationship with the number of poles Pin of the drive-side magnet 20 and the number of poles Pf of the fixed magnet 40: Npp=(Pin+Pf) / 2 This allows the rotational force of the drive-side magnet 20 to be transmitted to the pole piece 25. When the rotational force of the drive-side magnet 20 is transmitted to the pole piece 25, the rotating member 41, which is the output shaft of the power transmission device 1, rotates, and when the rotational force of the rotating member 41 is transmitted to the valve element 48, the valve element 48 moves in the axial direction. When the valve element 48 moves in the axial direction, the valve port 52a of the valve chamber 52 is opened or closed, and the flow rate of the refrigerant passing through the valve port 52a is adjusted.

[0097] At this time, in non-contact connecting portion 60, because partition wall 51 is magnetized, a magnetic circuit MC is formed in which magnetic flux flows in parallel as shown in Fig. 5. That is, as paths through which magnetic flux flows, a torque generation path φ1 shown by the solid arrows in Fig. 3 and Fig. 5 and a short-circuit magnetic flux path φ2 shown by the dashed arrows in Fig. 3 and Fig. 5 are formed.

[0098] In the torque generation path φ1, the magnetic flux flows in the order of the N pole 20n of the drive-side magnet 20, the partition wall 51, the magnetic material portion 25a of the pole piece 25, the fixed magnet 40, the back yoke 56, the fixed magnet 40, the magnetic material portion 25a of the pole piece 25, the partition wall 51, and the S pole 20s of the drive-side magnet 20. In the short-circuit magnetic flux path φ2, the magnetic flux flows in the order of the N pole 20n of the drive-side magnet 20, the partition wall 51, and the S pole 20s of the drive-side magnet 20.

[0099] The torque generation path φ1 carries magnetic flux that contributes to the generation of torque between the pole piece 25 and the fixed magnet 40. The short-circuit magnetic flux path φ2 carries magnetic flux that is short-circuited and does not contribute to the generation of torque.

[0100] 6 is a graph showing the relationship between the magnetic permeability of partition wall 51 and the torque (hereinafter referred to as the transmission torque) generated between pole piece 25 and fixed magnet 40. The magnetic permeability of partition wall 51 is between the magnetic permeability of a vacuum and that of iron. This graph is convex upward, and the transmission torque is maximized when the magnetic permeability is a predetermined value (approximately 30% in the example of FIG. 6).

[0101] In the low permeability region, the higher the permeability of the partition wall 51, the larger the transmission torque. This is because more magnetic flux penetrates the partition wall 51, and more magnetic flux flows through the torque generation path φ1. On the other hand, in the high permeability region, the higher the permeability of the partition wall 51, the smaller the transmission torque. This is because the amount of magnetic flux flowing through the short-circuit magnetic flux path φ2 increases significantly, and less magnetic flux flows through the torque generation path φ1.

[0102] From the above, it is preferable that the magnetic permeability of partition wall 51 is within ±20% (about 10% to about 50% in the example of FIG. 6) of the magnetic permeability at which the transmission torque is maximized (about 30% in the example of FIG. 6), since a large transmission torque can be generated. It is even more preferable that the magnetic permeability of partition wall 51 is within ±10% (about 20% to about 40% in the example of FIG. 6) of the magnetic permeability at which the transmission torque is maximized, since a torque that is nearly the maximum can be generated.

[0103] To provide the partition wall 51 with the desired magnetic permeability, the partition wall 51 is made of stainless steel that is made magnetic by transforming austenitic stainless steel such as SUS305 into martensite through work hardening, thereby improving the pressure resistance of the partition wall 51.

[0104] In this embodiment, a magnetic circuit MC is provided in which magnetic flux from the drive-side magnet 20 flows in parallel, and the magnetic circuit MC forms a torque generation path φ1 and a short-circuit magnetic flux path φ2. In the torque generation path φ1, magnetic flux flows from the north pole 20n of the drive-side magnet 20 via the pole piece 25 and the fixed magnet 40 to the south pole 20s of the drive-side magnet 20, generating torque. In the short-circuit magnetic flux path φ2, magnetic flux flows from the north pole 20n of the drive-side magnet 20 to the south pole 20s of the drive-side magnet 20, short-circuiting, without passing through the pole piece 25.

[0105] According to this, by forming the short-circuit magnetic flux path φ2, it is possible to increase the magnetic flux flowing through the torque generation path φ1, thereby making it possible to improve the transmission torque.

[0106] In this embodiment, the partition wall 51 is disposed between the drive-side magnet 20 and the pole piece 25, and has a magnetic permeability higher than that of a vacuum, forming the short-circuit magnetic flux path φ2. This allows the short-circuit magnetic flux path φ2 to be formed well.

[0107] In this embodiment, the magnetic permeability of the partition wall 51 is between the magnetic permeability of a vacuum and the magnetic permeability of iron. Specifically, the difference between the magnetic permeability of the partition wall 51 and the magnetic permeability at which the torque is maximized is within ±20%. More specifically, the difference between the magnetic permeability of the partition wall 51 and the magnetic permeability at which the torque is maximized is within ±10%.

[0108] This allows the amount of magnetic flux flowing through the torque generation path φ1 to be appropriate, thereby increasing the magnetic flux flowing through the torque generation path φ1, thereby improving the transmission torque.

[0109] In this embodiment, the partition wall 51 is made of austenitic stainless steel and has martensite, which makes it possible to easily form the partition wall 51 with appropriate magnetic permeability and increase the strength of the partition wall 51.

[0110] In this embodiment, the partition wall 51 divides the space into a drive-side space 113a, which is the space on the drive-side magnet 20 side, and a driven-side space 113b, which is the space on the pole piece 25 side. This allows the number of parts to be reduced compared to when the member that forms the short-circuit magnetic flux path φ2 is a separate member from the partition wall 51.

[0111] In this embodiment, the partition wall 51 forms part of a pressure vessel that seals the driven-side space 113b to have pressure resistance, which reduces the number of parts compared to when the member that forms the short-circuit magnetic flux path φ2 is a separate member from the pressure vessel.

[0112] (Second embodiment) In the first embodiment, the partition wall 51 is formed of stainless steel obtained by transforming austenitic stainless steel such as SUS305 into martensite through work hardening to impart magnetism to the stainless steel. However, in the present embodiment, as shown in FIG. 7 , the partition wall 51 is formed by laminating a non-magnetic layer 511 and a magnetic layer 512.

[0113] The non-magnetic layer 511 is made of a non-magnetic material. The magnetic layer 512 is made of a magnetic material. By appropriately setting the ratio between the non-magnetic layer 511 and the magnetic layer 512, the magnetic permeability of the partition wall 51 can be appropriately set. In this embodiment, the same effects as those in the first embodiment can be achieved.

[0114] In this embodiment, the partition wall 51 is formed of multiple layers, namely, the non-magnetic layer 511 and the magnetic layer 512, and of the multiple layers, the magnetic layer 512 is made of a magnetic material. This makes it possible to easily form the partition wall 51 having appropriate magnetic permeability.

[0115] (Third embodiment) The magnetic gear 60b in the first embodiment is a radial type magnetic gear 60b in which the drive side magnet 20, the pole piece 25, and the fixed magnet 40 are stacked radially, but the magnetic gear 60b in this embodiment is an axial type magnetic gear 60b in which the drive side magnet 20, the pole piece 25, and the fixed magnet 40 are stacked axially, as shown in Figure 8.

[0116] In this embodiment, as in the first embodiment, a magnetic circuit MC is formed having a torque generation path φ1 and a short-circuit magnetic flux path φ2 that are parallel to each other, and therefore, by imparting a desired magnetic permeability to the partition wall 51, a large transmission torque can be generated.

[0117] (Fourth embodiment) The magnetic gear 60b in the first embodiment is a radial type magnetic gear 60b in which the drive side magnet 20, pole piece 25, and fixed magnet 40 are stacked radially, but the magnetic gear 60b in this embodiment is a linear type magnetic gear 60b in which the drive side magnet 20, pole piece 25, and fixed magnet 40 are formed in the shape of long plates and stacked so as to face each other, as shown in Figure 9.

[0118] In this embodiment, as in the first embodiment, a magnetic circuit MC is formed having a torque generation path φ1 and a short-circuit magnetic flux path φ2 that are parallel to each other, and therefore, by imparting a desired magnetic permeability to the partition wall 51, a large transmission torque can be generated.

[0119] The present disclosure is not limited to the above-described embodiments, and various modifications can be made as follows within the scope of the present disclosure.

[0120] In the first embodiment, the partition wall 51 is formed of stainless steel obtained by transforming austenitic stainless steel such as SUS305 into martensite through work hardening to impart magnetism, but the partition wall 51 may also be formed of a magnetic metal obtained by reducing the magnetic permeability by distorting a magnetic metal such as an electromagnetic steel plate. The partition wall 51 may also be formed of a resin mixed with iron powder.

[0121] In the first embodiment described above, the pole piece 25 and the fixed magnet 40 are arranged radially outside the driving side magnet 20, but the pole piece 25 and the fixed magnet 40 may also be arranged radially inside the driving side magnet 20.

[0122] In the above embodiment, the present disclosure is applied to an expansion valve of a vapor compression refrigeration cycle, but the present disclosure is not limited to the expansion valve and can be applied to various motor-operated valves that open and close a valve port through which a fluid passes using a valve element. In addition to motor-operated valves, the present disclosure can be applied to power transmission devices that transmit power from various driving devices to various driven devices.

[0123] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

[0124] The power transmission device and expansion valve disclosed in this specification have the following features:

[0125] (Item 1) a magnetic gear (60b) having an input shaft magnet (20) to which a rotational driving force is input, a magnetic modulation section (25) that modulates magnetic flux, a multi-pole magnet (40) having a larger number of poles than the input shaft magnet, and an output shaft (41) that rotates integrally with the magnetic modulation section or the multi-pole magnet; a magnetic circuit (MC) through which magnetic flux from the input shaft magnet flows in parallel, The magnetic circuit comprises: a torque generation path (φ1) through which magnetic flux flows from the north pole (20n) of the input shaft magnet via the magnetic modulation unit and the multi-pole magnet to the south pole (20s) of the input shaft magnet, generating torque; A power transmission device that forms a short-circuit magnetic flux path (φ2) in which magnetic flux flows from the N pole of the input shaft magnet to the S pole of the input shaft magnet without passing through the magnetic modulation section.

[0126] (Item 2) Item 1. The power transmission device according to item 1, further comprising: a short-circuit magnetic flux forming member (51) between the input shaft magnet and the magnetic modulation unit, the short-circuit magnetic flux forming member having a magnetic permeability higher than that of a vacuum and forming the short-circuit magnetic flux path.

[0127] (Item 3) 3. The power transmission device according to item 2, wherein the magnetic permeability of the short-circuit magnetic flux forming member is between the magnetic permeability of a vacuum and the magnetic permeability of iron.

[0128] (Item 4) 4. The power transmission device according to item 2 or 3, wherein the difference between the magnetic permeability of the short-circuit magnetic flux forming member and the magnetic permeability at which the torque is maximized is within ±20%.

[0129] (Item 5) 5. The power transmission device according to any one of items 2 to 4, wherein the difference between the magnetic permeability of the short-circuit magnetic flux generating member and the magnetic permeability at which the torque is maximized is within ±10%.

[0130] (Item 6) 6. The power transmission device according to any one of items 2 to 5, wherein the short-circuit magnetic flux generating member is formed of a plurality of layers, some of which are made of magnetic material.

[0131] (Item 7) 6. The power transmission device according to any one of items 2 to 5, wherein the short-circuit magnetic flux forming member is an austenitic stainless steel having martensite.

[0132] (Item 8) 8. The power transmission device according to any one of items 2 to 7, wherein the short-circuit magnetic flux forming member is a partition wall (51) that separates the drive side space (113a), which is a space on the input shaft magnet side, from a driven side space (113b), which is a space on the magnetic modulation unit side.

[0133] (Item 9) 9. The power transmission device according to item 8, wherein the short-circuit magnetic flux generating member forms a part of a pressure vessel (50, 51) that seals the driven-side space so as to have pressure resistance.

[0134] (Item 10) A power transmission device (1) according to any one of items 1 to 9; a valve opening forming member (50) that forms a valve opening (52a) through which a refrigerant of a vapor compression refrigeration cycle (110) flows; and a valve body (48) that adjusts the opening of the valve port by the torque transmitted by the power transmission device.

Claims

1. a magnetic gear (60b) having an input shaft magnet (20) to which a rotational driving force is input, a magnetic modulation section (25) that modulates magnetic flux, a multi-pole magnet (40) having a larger number of poles than the input shaft magnet, and an output shaft (41) that rotates integrally with the magnetic modulation section or the multi-pole magnet; a magnetic circuit (MC) through which magnetic flux from the input shaft magnet flows in parallel, The magnetic circuit comprises: a torque generation path (φ1) through which magnetic flux flows from the north pole (20n) of the input shaft magnet via the magnetic modulation unit and the multi-pole magnet to the south pole (20s) of the input shaft magnet to generate torque; a short-circuit magnetic flux path (φ2) in which magnetic flux flows by short-circuiting from the N pole of the input shaft magnet to the S pole of the input shaft magnet without passing through the magnetic modulation unit; The magnetic modulation unit further includes a short-circuit magnetic flux forming member (51) that is disposed between the input shaft magnet and the magnetic modulation unit, has a magnetic permeability higher than that of a vacuum, and forms the short-circuit magnetic flux path, A power transmission device, wherein the difference between the magnetic permeability of the short-circuit magnetic flux forming member and the magnetic permeability at which the torque is maximized is within ±20%.

2. a magnetic gear (60b) having an input shaft magnet (20) to which a rotational driving force is input, a magnetic modulation section (25) that modulates magnetic flux, a multi-pole magnet (40) having a larger number of poles than the input shaft magnet, and an output shaft (41) that rotates integrally with the magnetic modulation section or the multi-pole magnet; a magnetic circuit (MC) through which magnetic flux from the input shaft magnet flows in parallel, The magnetic circuit comprises: a torque generation path (φ1) through which magnetic flux flows from the north pole (20n) of the input shaft magnet via the magnetic modulation unit and the multi-pole magnet to the south pole (20s) of the input shaft magnet to generate torque; a short-circuit magnetic flux path (φ2) in which magnetic flux flows by short-circuiting from the N pole of the input shaft magnet to the S pole of the input shaft magnet without passing through the magnetic modulation unit; The magnetic modulation unit further includes a short-circuit magnetic flux forming member (51) that is disposed between the input shaft magnet and the magnetic modulation unit, has a magnetic permeability higher than that of a vacuum, and forms the short-circuit magnetic flux path, A power transmission device, wherein the difference between the magnetic permeability of the short-circuit magnetic flux forming member and the magnetic permeability at which the torque is maximized is within ±10%.

3. a magnetic gear (60b) having an input shaft magnet (20) to which a rotational driving force is input, a magnetic modulation section (25) that modulates magnetic flux, a multi-pole magnet (40) having a larger number of poles than the input shaft magnet, and an output shaft (41) that rotates integrally with the magnetic modulation section or the multi-pole magnet; a magnetic circuit (MC) through which magnetic flux from the input shaft magnet flows in parallel, The magnetic circuit comprises: a torque generation path (φ1) through which magnetic flux flows from the north pole (20n) of the input shaft magnet via the magnetic modulation unit and the multi-pole magnet to the south pole (20s) of the input shaft magnet to generate torque; a short-circuit magnetic flux path (φ2) in which magnetic flux flows by short-circuiting from the N pole of the input shaft magnet to the S pole of the input shaft magnet without passing through the magnetic modulation unit; The magnetic modulation unit further includes a short-circuit magnetic flux forming member (51) that is disposed between the input shaft magnet and the magnetic modulation unit, has a magnetic permeability higher than that of a vacuum, and forms the short-circuit magnetic flux path, The power transmission device, wherein the short-circuit magnetic flux forming member is an austenitic stainless steel having martensite.

4. a magnetic gear (60b) having an input shaft magnet (20) to which a rotational driving force is input, a magnetic modulation section (25) that modulates magnetic flux, a multi-pole magnet (40) having a larger number of poles than the input shaft magnet, and an output shaft (41) that rotates integrally with the magnetic modulation section or the multi-pole magnet; a magnetic circuit (MC) through which magnetic flux from the input shaft magnet flows in parallel, The magnetic circuit comprises: a torque generation path (φ1) through which magnetic flux flows from the north pole (20n) of the input shaft magnet via the magnetic modulation unit and the multi-pole magnet to the south pole (20s) of the input shaft magnet to generate torque; a short-circuit magnetic flux path (φ2) in which magnetic flux flows by short-circuiting from the N pole of the input shaft magnet to the S pole of the input shaft magnet without passing through the magnetic modulation unit; The magnetic modulation unit further includes a short-circuit magnetic flux forming member (51) that is disposed between the input shaft magnet and the magnetic modulation unit, has a magnetic permeability higher than that of a vacuum, and forms the short-circuit magnetic flux path, the short-circuit magnetic flux forming member is a partition wall (51) that divides the space into a drive-side space (113a) that is a space on the input shaft magnet side and a driven-side space (113b) that is a space on the magnetic modulation unit side, The power transmission device, wherein the short-circuit magnetic flux generating member forms part of a pressure vessel (50, 51) that seals the driven-side space so as to have pressure resistance.

5. 5. The power transmission device according to claim 1, wherein the magnetic permeability of the short-circuit magnetic flux generating member is between the magnetic permeability of a vacuum and the magnetic permeability of iron.

6. 5. The power transmission device according to claim 3, wherein the magnetic permeability of the short-circuit magnetic flux generating member has a difference of ±20% or less from the magnetic permeability at which the torque becomes maximum.

7. 5. The power transmission device according to claim 3, wherein the magnetic permeability of the short-circuit magnetic flux generating member has a difference of ±10% or less from the magnetic permeability at which the torque becomes maximum.

8. 5. The power transmission device according to claim 1, wherein the short-circuit magnetic flux generating member is formed of a plurality of layers, and a portion of the plurality of layers, namely, a layer (512), is made of a magnetic material.

9. 3. The power transmission device according to claim 1, wherein the short-circuit magnetic flux forming member is made of austenitic stainless steel and contains martensite.

10. 4. The power transmission device according to claim 1, wherein the short-circuit magnetic flux forming member is a partition wall (51) that separates the drive space (113a), which is a space on the input shaft magnet side, from a driven space (113b), which is a space on the magnetic modulation unit side.

11. 11. The power transmission device according to claim 10, wherein the short-circuit magnetic flux generating member forms a part of a pressure vessel (50, 51) that seals the driven-side space so as to have pressure resistance.

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