Liquid-cooled motor

Abstract

The present invention includes: a housing; a rotor that rotates about an axis with respect to the housing; a stator that is fixed to the housing and that generates a magnetic force for rotation with respect to the rotor, at least a portion thereof being formed of a material having a linear expansion coefficient different from that of the housing; a flow path that is provided so as to extend across the end surfaces of the housing and the stator in the axial direction, that is formed in the housing, and through which the cooling liquid passes; an end plate that is disposed facing the flow path; and a fastening member that generates fastening force in a direction in which the end plate is brought into close contact with the housing and the stator.

Description

Liquid-cooled motor CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority from Japanese Patent Application No. 2024-010018, the disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a liquid-cooled motor in which a stator is cooled with a cooling liquid.

[0003] In recent years, the electrification of aircraft and automobiles has led to a demand for lightweight, high-output (high power density) motors for driving them. As a result, the heat generation density of the stator core and coils has increased, causing problems with motor temperature rise. To address this issue, a method has been adopted in which cooling oil is circulated inside the motor to directly cool the stator core and coils.

[0004] An example of the cooling method is shown in Figure 6 of Japanese Patent No. 3882637. In this method, a stator cooling passage is formed by a case (housing), a stator core (stator), and seal rings that are held in place by snap rings at both axial ends of the stator core, and cooling oil is passed through the stator cooling passage to cool the stator core and coils.

[0005] To fix the stator core to the case, spline teeth are intermittently arranged at equal angular positions in the circumferential direction on both the case and the stator core, and the spline teeth are aligned and fitted together.

[0006] Japanese Patent No. 3882637

[0007] A method of fixing a stator core to a case by shrink fitting is known. In particular, when a case (housing) that houses a motor is made of, for example, aluminum or resin to achieve the lightweight requirements for electric aircraft applications, a difference in linear expansion occurs between the case and a stator core made of a different material, a magnetic material. This can cause the stator core to become loose when used over a wide temperature range. For this reason, it has been necessary to tighten the interference of the shrink fitting to prevent the loosening of the fixation.

[0008] However, if the shrink fit interference is too tight, the stator core cannot withstand the stress caused by the interference, which can lead to deformation or buckling of the stator core. To prevent this, it is possible to increase the radial thickness of the stator core and the thickness of the housing, thereby designing the stator core to withstand the stress caused by the interference. However, this results in an increase in the motor mass. Incidentally, one problem with increasing the thickness is that the thermal resistance due to heat conduction in the stator core increases, resulting in a deterioration in cooling efficiency.

[0009] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a liquid-cooled motor that can suppress an increase in motor mass even when the housing and stator are made of different materials.

[0010] The liquid-cooled motor of the present invention comprises a housing, a rotor that rotates around an axis relative to the housing, and a stator that is fixed to the housing and generates a magnetic force for the rotor to rotate, with at least a portion of the stator being formed from a material with a linear expansion coefficient different from that of the housing, a flow path formed within the housing through which a cooling liquid flows, an end plate that is arranged across the end faces of the housing and the stator in the axial direction and faces the flow path, and a fastening member that generates a fastening force in a direction that presses the end plate tightly against the housing and the stator.

[0011] In addition, the liquid-cooled motor of the present invention may further include a partition wall arranged along the axial direction between the rotor and the stator to divide the flow path, the stator having a coil, the stator having coil slots extending in the axial direction to hold the coil, the coil slots having an intra-slot space extending over the entire axial length of the stator, and the intra-slot space constituting part of the flow path through which the cooling liquid passes.

[0012] Furthermore, in the liquid-cooled motor of the present invention, the flow path may have a buffer portion in which the cross-sectional area of ​​a cross section perpendicular to the direction in which the cooling liquid flows is enlarged.

[0013] The liquid-cooled motor of the present invention may further include a sealing member between the housing and the end plate for preventing leakage of the cooling liquid.

[0014] The flow path may be formed inside the housing and facing the stator.

[0015] The stator may be fixed between the housing and the end plate, so that the flow path is formed surrounded by the stator, the housing, and the end plate.

[0016] The fastening member may also be configured to generate the fastening force in the direction of the axis.

[0017] The housing may also comprise a housing main body having a side wall portion at one end in the axial direction and an opening at the other end, and a lid body that closes the opening of the housing main body, the lid body having an inlet-side through hole and an outlet-side through hole provided at a position different from the inlet-side through hole, the inlet-side through hole being a portion through which a supply pipe that supplies the cooling liquid to the flow path from outside the motor passes, and the outlet-side through hole being connected to the flow path and being a portion through which the cooling liquid that has passed through the flow path is discharged to the outside of the motor.

[0018] In addition, an end space may be formed between the end of the stator in the axial direction and the housing, and the housing may have a cutout portion that connects the flow path and the end space.

[0019] The fastening member may have a length that extends across both ends of the stator in the axial direction.

[0020] The stator may have a bulging portion that protrudes radially outward.

[0021] The housing may also have a recessed portion on the radially outer side of the bulging portion, the recessed portion facing the bulging portion.

[0022] The housing may also be configured to have an inlet and an outlet for the cooling liquid, with the inlet connected to a guide pipe that guides the cooling liquid supplied by a pump from an external storage section that stores the cooling liquid, and the outlet connected to a discharge pipe that returns the cooling liquid that has cooled the stator to the storage section via a heat exchanger.

[0023] FIG. 1 shows a liquid-cooled motor according to a first embodiment of the present invention, with the exception of the rotor, in cross section. FIG. 2 shows a liquid-cooled motor according to a second embodiment of the present invention, with the exception of the rotor, in cross section. FIG. 3 shows a liquid-cooled motor according to a third embodiment of the present invention, with the exception of the rotor, in cross section. FIG. 4 shows a liquid-cooled motor according to a fourth embodiment of the present invention, with the exception of the rotor, in cross section. FIG. 5 shows another embodiment in which an adhesive layer is added to a main portion of the liquid-cooled motor according to the first embodiment of the present invention. FIG. 6 shows another liquid-cooled motor in which bolt through holes are formed in the stator core, with the exception of the rotor, in cross section. FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 6. FIG. 8 shows another liquid-cooled motor in which the stator cooling passages are used as bolt through holes, with the exception of the rotor, in cross section. FIG. 9A is a cross-sectional view of a main portion of the housing shown in FIG. 7, with a modified shape. FIG. 9B is a cross-sectional view of a main portion of the housing shown in FIG. 7, with a modified shape. FIG. 10 is a block diagram showing a system that combines a liquid-cooled motor according to each embodiment of the present invention with a configuration for supplying cooling liquid to the liquid-cooled motor.

[0024] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid-cooled motor (hereinafter simply referred to as a motor) according to an embodiment of the present invention will be described with reference to the accompanying drawings.

[0025] First Embodiment As shown in Fig. 1, a motor 1 includes a housing 3 for housing a motor unit 2 that generates power. A partition wall 4 for covering a stator 9, which will be described later, is provided inside the housing 3. To achieve weight reduction, the housing 3 is made of, for example, aluminum, an aluminum alloy, a titanium alloy, a magnesium alloy, a metal composite material, a carbon fiber composite (CFRP), or a synthetic resin. In the following description, the direction along the axis X of a rotating shaft 5, which will be described later, in Fig. 1 is defined as the axial direction, and the direction perpendicular to the axial direction (the up-down direction in Fig. 1) is defined as the radial direction.

[0026] The housing 3 is provided with an inlet IN and an outlet OUT for the cooling liquid. As shown in Fig. 10 (block diagram), a guide pipe 103 is connected to the inlet IN, which guides the cooling liquid supplied by a pump 102 from a tank 101, which is an external storage unit for storing the cooling liquid, and a discharge pipe 104 is connected to the outlet OUT, which returns the cooling liquid heated by cooling the stator 9 (described below) to the tank 101 via a heat exchanger 105 that performs cooling. In this embodiment, cooling oil is used as the cooling liquid, but water or various other cooling media may also be used.

[0027] The motor 1 is configured as an inner rotor type, with a rotor 8 (described later) attached radially inside a stator 9 (described later) so as to rotate integrally with a rotary shaft 5 that is rotatably supported approximately at the center of the housing 3. The motor 1 may be used, for example, as an electric motor for aircraft or a driving source for automobiles, as a driving source for actuators such as robots, as a driving source for pumps and compressors, as a flywheel power storage device, or for other purposes.

[0028] As shown in FIG. 1 , the housing 3 includes a cylindrical housing body 32 having a sidewall 31 at one axial end (the right end in FIG. 1 ), and a lid 33 that closes an opening at the other axial end (the left end in FIG. 1 ) of the housing body 32. In this embodiment, as shown in FIG. 1 , an inlet (IN) for the cooling liquid is formed at the other axial end (left side) of the lower part of the housing body 32 (it may be at the upper part, the middle part in the vertical direction, or other parts other than the lower part), and an outlet (OUT) for the cooling liquid is formed at the one axial end (right side) of the lower part of the housing body 32. The cooling liquid that enters through the inlet (IN) for the cooling liquid flows through an annular flow path 6 formed within the housing 3 toward the one axial end (the right side) in FIG. 1 and is discharged to the outside through the outlet (OUT). The flow path 6 forms a stator cooling passage 61 that cools a stator core 91 (described below). In this embodiment, by arranging the inlet (IN) and outlet (OUT) for the cooling liquid at both axial ends of the stator, more space is created for the cooling liquid to flow toward the right in the axial direction, thereby achieving a cooling effect due to the flow of the cooling liquid.

[0029] The flow path 6 is formed by the radial inner surface 32A of the housing body 32, the end plate 10 described later, the radial outer surface 91b of the stator core 91 described later, and the vertical surface 323a of the annular step portion 323 formed to protrude from the side wall portion 31 of the housing body 32 toward one axial end (the right end in Figure 1) of the stator core 91 described later, which is perpendicular to the axial direction, among the vertical surfaces 323a and horizontal surfaces 323b.

[0030] A through-hole 31A is formed in the radial center of the side wall 31 of the housing main body 32, passing through one axial end (the right end in FIG. 1 ) of the rotating shaft 5 in the axial direction. Furthermore, a through-hole 33A is formed in the radial center of the cover 33, passing through the other axial end (the left end in FIG. 1 ) of the rotating shaft 5 in the axial direction. One end of the rotating shaft 5 passing through one of the through-holes 31A is rotatably supported by the side wall 31 of the housing main body 32 via a bearing 7A. The other end of the rotating shaft 5 passing through the other through-hole 33A is rotatably supported by the cover 33 via a bearing 7B.

[0031] The housing body 32 includes a thin-walled portion 321, a thick-walled portion 322, and a step portion 323. The thin-walled portion 321 has an opening at its left axial end. The thick-walled portion 322 is thicker than the thin-walled portion 321 and has a space therein for accommodating a stator core 91 (described later). The step portion 323 is formed so that the right axial end of the stator core 91 (described later) abuts against the end of the housing body 32 on the side wall portion 31 side. It is preferable that the left axial end face 91c of the stator core 91 (described later) accommodated in the thick-walled portion 322 protrudes slightly axially outward (to the left in FIG. 1 ) relative to the left axial end face 322a of the thick-walled portion 322. This allows the end plate 10 to bend and transmit axial force to the stator core 91 when the end plate 10 is bolted to the housing body 32, as described later. This seals the gap between the end plate 10 and the stator core 91.

[0032] The motor unit 2 includes a rotor 8 and a stator 9. The rotor 8 is fitted onto the rotating shaft 5 so as to rotate integrally with the housing 3 about the axis X. The stator 9 is disposed between the partition wall 4 and the housing main body 32. In other words, the stator 9 is positioned radially outward of the rotor 8. The rotor 8 has a plurality of permanent magnets (not shown) arranged along the circumferential direction. In this embodiment, a permanent magnet rotor is used, but any type of rotor may be used, such as a wound rotor or a cage rotor for an induction machine.

[0033] The stator 9 generates a magnetic force to rotate the rotor 8 and includes a stator core 91, coils 92, and an insulating member (not shown). The stator core 91 has multiple magnetic poles. The coils 92 are attached to the stator core 91. The insulating member provides insulation between the stator core 91 and the coils 92. The stator core 91 extends axially and includes teeth (not shown) arranged circumferentially. Coil slots (not shown; see coil slots 93 in FIG. 3 for the third embodiment) are formed between adjacent teeth in the axial direction to hold the coils 92. The coil slots have multiple intra-slot spaces (not shown; see intra-slot spaces 15 in FIG. 3 for the third embodiment) extending over the entire axial length of the stator core 91. As described below, the multiple intra-slot spaces form part of a flow path through which a cooling liquid passes. The stator core 91 is also composed of a laminate of electromagnetic steel sheets formed of a material (e.g., a soft magnetic material) different from that of the housing 3. That is, the stator core 91 is made of a material with a linear expansion coefficient different from that of the housing 3 (the aforementioned material (metal) containing aluminum, synthetic resin, etc.). In this embodiment, the stator core 91 is made of a laminate of electromagnetic steel sheets, but it can also be made of a material such as silicon steel sheet, permendur (cobalt steel), or permalloy.

[0034] The partition wall 4 is made of glass fiber reinforced plastic (GFRP), which is nonmagnetic and can be formed into a thin-walled cylindrical shape. Among plastics, glass fiber reinforced plastic (GFRP) has a low linear expansion coefficient. The axial length of the partition wall 4 is longer than the axial length (axial length) of the stator core 91. More specifically, the partition wall 4 is configured to protrude axially outward beyond the axially outer ends of the coils 92, which protrude axially outward from the stator core 91. One axial end (the right end in FIG. 1 ) of the partition wall 4 abuts against the end surface 31 a of the side wall portion 31 of the housing main body 32, and the other axial end (the left end in FIG. 1 ) of the partition wall 4 abuts against the end surface 33 a of the cover 33. This separates the space housing the stator 9 from the space housing the rotor 8 by the partition wall 4. The partition wall 4 is also fixed to the entire inner surface 91 a of the stator core 91 with an adhesive (not shown). This ensures the rigidity of the partition wall 4.

[0035] To form the flow path 6, an end plate 10 is disposed facing the flow path 6. The end plate 10 is made of a metal material (iron, stainless steel, aluminum, etc.) and is configured as a disk with a circular through-hole 10A in the center. A bolt hole 10a is formed on the radially outer side of the end plate 10, through which the shank of a bolt 11 (described later) can pass. The end plate 10 may also be made of synthetic resin. The end plate 10 is disposed so as to extend between the axial left end surface 322a of the thick-walled portion 322 of the housing body 32 and the axial left end surface 91c of the stator core 91. The end plate 10 is fastened by inserting the shank of a bolt 11 (as a fastening member) through the bolt hole 10a and threading it into a threaded portion 322N formed in the thick-walled portion 322 of the housing body 32, thereby tightly adhering the end plate 10 to the housing 3 and the stator core 91 with a fastening force. This prevents leakage of the cooling liquid from the flow path 6 due to the fastening force applied to the end plate 10. This eliminates the need to form spline teeth to form flow paths in the case and the stator core. Furthermore, shrink fitting to secure the end plate 10 to the housing 3 is also unnecessary. This eliminates the need to increase the radial thickness of the motor 1, thereby suppressing an increase in motor mass. The number of bolts 11 may be one, or any number of bolts equal to or greater than two. When there is one bolt 11, it is desirable to use it in combination with other means such as fitting. When there are multiple bolts 11, it is desirable to arrange them evenly in the circumferential direction.

[0036] 2, the second embodiment differs from the first embodiment (FIG. 1) in that a sealing member 12 is provided between the housing 3 and the end plate 10 to prevent leakage of the cooling liquid due to temperature changes, etc. A part of the sealing member 12 is fitted into an annular groove 322M formed in the thick portion 322 of the housing body 32 of the housing 3.

[0037] The sealing member 12 is an annular sealing member (e.g., an O-ring) made of, for example, a rubber-like elastic material. By providing the sealing member 12, even if a gap occurs between the housing 3 and the end plate 10 due to temperature changes caused by the motor operating conditions or the temperature outside the motor, the sealing member 12 fills the gap, thereby preventing leakage of the cooling liquid, which is preferable.

[0038] 2, the sealing member 12 is provided only between the housing 3 and the end plate 10, but it is preferable to provide a sealing member (not shown) between the stator core 91 and the end plate 10 in addition to this. Also, a plurality of sealing members 12 (for example, a plurality of O-rings arranged concentrically) may be provided in the circumferential direction between the housing 3 and the end plate 10. Note that parts not described in FIG. 2 are the same as those in FIG. 1, and are therefore denoted by the same reference numerals as in FIG. 1, and description thereof will be omitted.

[0039] Third Embodiment The third embodiment is shown in FIG. 3 . This embodiment differs from the first embodiment ( FIG. 1 ) in that cooling liquid is supplied to the inlet of one longitudinal end (the left end in FIG. 3 ) of the stator cooling passage 61, which constitutes the flow path 6, in the same direction as the cooling liquid flowing through the stator cooling passage 61. This ensures smooth flow of the cooling liquid. This reduces pressure loss and the discharge pressure of the pump that supplies the cooling liquid, thereby improving system efficiency. The cooling liquid is also configured to flow from the stator cooling passage 61 to the coil cooling passage 62 (described below). Therefore, the partition 4 is provided to prevent cooling liquid from leaking radially inward from both axial ends of the partition 4. The cooling liquid is supplied to the flow path 6 through a cylindrical oil supply port (oil supply pipe) 13 that penetrates a through-hole 33K formed in the cover 33 and has its right axial end connected to a through-hole 10K formed in the end plate 10. The supplied cooling liquid moves from one end side (the right end side in FIG. 3 ) of the flow path 6 in the direction of flow, through a notch 323K formed in part of the circumferential direction of the step 323 of the housing main body 32, to an annular first space 14 about the axis X formed by the stator core 91, the step 323, the side wall 31, and the partition wall 4. In other words, the notch 323K has a space communicating with the stator cooling passage 61 and the first space 14. The cooling liquid that has moved to the first space 14 enters the intra-slot spaces 15 formed in each of the multiple coil slots 93 formed in the stator core 91, moves to an annular second space 16 about the axis X formed at the left end in FIG. 3 , and is discharged to the outside from an outlet 33B formed in the lid 33.

[0040] The slot space 15 forms a coil cooling passage 62 that cools the coil 92 with a cooling liquid. A cylindrical oil drain port (oil drain pipe, not shown) may be connected to the outlet 33B. It is desirable to provide two or more notches 323K in the circumferential direction, but one notch may also be provided. The flow path 6 includes a stator cooling passage 61 formed outside the stator core 91 and a plurality of coil cooling passages 62 formed inside the stator core 91.

[0041] The cooling liquid moves into the first space 14 and comes into contact with the surface of the coil end portion 92A of the coil 92, and then moves further into the slot space 15 and comes into contact with the surface of the coil 92 in the coil cooling passage 62. As a result, the heat generated by copper loss in the coil 92 is directly absorbed by the cooling liquid, thereby enabling efficient cooling.

[0042] 3, the cooling liquid flows through the stator cooling passage 61 and then through the coil cooling passage 62. This allows the flow paths inside and outside the stator core 91 to be integrated into a single flow path. This allows the piping of the stator cooling passage 61 and the coil cooling passage 62 to be shared, resulting in a smaller, lighter, and more simplified configuration. Furthermore, the pump for supplying the cooling liquid can be integrated into a single system, resulting in a smaller and lighter system including the tank, pump, and motor.

[0043] 3, the pipe connection surfaces for connecting the oil supply pipe that supplies the cooling liquid and the oil drain pipe that discharges the supplied cooling liquid are on the same surface (the outer surface of the lid 33), simplifying piping work. Furthermore, since there are no pipe connection points on the housing main body 32, the outer diameter of the housing 3 can be reduced. Even if the cooling liquid in the flow path 6 leaks from the end plate 10 to the left in the axial direction in FIG. 3, it simply moves to the second space 16 for discharging the cooling liquid and does not directly leak outside the housing 3, improving the reliability of the sealing structure. Note that parts not described in FIG. 3 are the same as those in FIG. 1, and are therefore designated by the same reference numerals as in FIG. 1, and their description will be omitted.

[0044] Fourth Embodiment The fourth embodiment is shown in FIG. 4 . The fourth embodiment is a partial modification of the third embodiment ( FIG. 3 ). The fourth embodiment differs from the third embodiment in that the annular stator cooling passage 61 constituting the flow path 6 includes an annular buffer portion 17. The buffer portion 17 is a passage having an enlarged cross-sectional area in a cross section perpendicular to the direction in which the cooling liquid flows. In the fourth embodiment, the cooling liquid that flows through the stator cooling passage 61 toward one axial end (right side) does not flow toward the coil 92 as shown in FIG. 3 , but flows to a cooling liquid outlet OUT (the same as in FIG. 1 ) formed at one axial end (right side) of the lower part of the housing main body 32 and is discharged to the outside of the housing 3.

[0045] The buffer portion 17 is formed around the entire circumference of the inlet end of the stator cooling passage 61, which receives the cooling liquid. The cross-sectional area of ​​the buffer portion 17 may be any size as long as it is larger than the cross-sectional area of ​​the remaining portions of the stator cooling passage 61. Furthermore, the length of the buffer portion 17 in the direction in which the cooling liquid flows (depth direction (axial direction)) is not limited to the length shown in FIG. 4 . The provision of the buffer portion 17 creates a retention space with lower fluid resistance than the flow path portions of the stator cooling passage 61 with smaller cross-sectional areas. The cooling liquid is retained in the buffer portion 17 before flowing into the stator cooling passage 61. This allows a uniform flow rate of the cooling liquid to be supplied to the stator cooling passage 61, which is a flow path connected through the buffer portion 17. Furthermore, providing the buffer portion 17 at the inlet end of the stator cooling passage 61 in FIG. 3, which receives the cooling liquid, allows the cooling liquid to flow relatively evenly through the multiple coil cooling passages 62, which are flow paths with high fluid resistance (e.g., flow paths within the coil slots). In this embodiment, the cross-sectional area of ​​the buffer section 17 is constant from the start to the end in the direction of the flow of the cooling liquid, but the cross-sectional area may be configured to increase or decrease from the start to the end. If the cross-sectional area changes in the direction of the flow of the cooling liquid in this way, heat transfer may be improved. Note that parts not described in Figure 4 are the same as those in Figures 1 and 3, and are denoted by the same reference numerals as in Figures 1 and 3, and their description will be omitted.

[0046] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0047] For example, in the first embodiment ( FIG. 1 ), a core laminate having a large outer diameter is formed by stacking multiple flat electromagnetic steel plates at the axial left end of the stator core 91. The large-diameter core laminate is then sandwiched between the axial left end face 322 a of the thick-walled portion 322 and the end plate 10. Each electromagnetic steel plate has a through-hole through which a bolt 11 passes. In this sandwiched state, the bolt 11 may be passed through the core laminate and then screwed into the threaded portion 322N of the thick-walled portion 322 to fix the end plate 10 to the housing 3. By interposing the core laminate between the thick-walled portion 322 and the end plate 10 in this manner, no gap is generated between the end plate 10 and the axial left end face 322 a of the thick-walled portion 322, thereby suppressing stress on the end plate 10. This reduces the amount of deformation of the end plate 10, allowing the end plate 10 to be made thinner, leading to a reduction in the weight of the end plate 10.

[0048] Alternatively, a configuration as shown in Fig. 5 may be used. In the configuration shown in Fig. 5, an adhesive layer 18 is formed between the radially outer surface 10B of the end plate 10 and the radially inner surface 321A of the thin-walled portion 321 in Fig. 1, thereby preventing radial displacement of the end plate 10. This adhesive layer 18 may be formed around the entire periphery of the end plate 10, or may be formed only in a specific portion in the circumferential direction.

[0049] In the first to fourth embodiments, an inner rotor motor is used, but an outer rotor motor may also be used. In the case of an outer rotor motor, the radial inner / outer relationship between the rotor and the stator is reversed from that in the above embodiments.

[0050] In the first and second embodiments, the partition wall 4 is provided, but it may be omitted.

[0051] In the third embodiment (FIG. 3), the cooling liquid flows through the stator cooling passage 61 and then into the coil cooling passage 62. However, the cooling liquid may alternatively flow through the coil cooling passage 62 and then into the stator cooling passage 61. In this case, by first flowing the cooling liquid at a lower temperature into the coil cooling passage 62, it is possible to more effectively cool the coil 92, which generates more heat than other parts.

[0052] In the third embodiment ( FIG. 3 ), the piping for the stator cooling passage 61 and the coil cooling passage 62 are shared so that the cooling liquid flows from the stator cooling passage 61 to the coil cooling passage 62. However, a piping (not shown) for forming the coil cooling passage or a cooling passage (not shown) for flowing a separate cooling liquid that does not intersect with the cooling liquid in the stator cooling passage 61 may be provided within the housing 3. In this case, if the housing 3 is configured to exchange heat between the stator cooling passage 61 and the piping or cooling passage within the housing 3, the housing 3 can function as a heat exchanger, thereby reducing the size and weight of the system (see FIG. 10 ) including the tank 101, pump 102, and motor 1. Furthermore, because the housing 3 itself serves as a heat exchanger, heat exchange efficiency can be improved by reducing piping losses compared to a system in which a separately provided heat exchanger is connected by piping.

[0053] Alternatively, the stator core 91 may be configured as shown in FIGS. 6 and 7 . That is, in the configurations shown in FIGS. 6 and 7 , bulging portions 91T bulging radially outward from the outer peripheral surface of the stator core 91 in an arc shape (which may be triangular, trapezoidal, rectangular, or the like) are provided at multiple locations around the circumferential direction (four locations in FIG. 7 , but any number of locations greater than two is acceptable). Bolt through holes 322A are formed in the bulging portions 91T, allowing the shanks 11A of the bolts 11 to pass through. A threaded hole 323N for threading the threaded portion 11N formed at the tip of the bolt 11 through the bolt through holes 322A is formed in a step portion 323 of the housing 3 (the right end portion in FIG. 6 ). Forming the bolt through holes 322A in this manner allows the shanks of the bolts 11 to be elongated, thereby enabling the bolts 11 to elastically deform and preventing the bolts 11 from loosening. Furthermore, by forming the bulging portion 91T, it is not necessary to increase the outer diameter of the stator core 91 to form the bolt through holes 322A, thereby preventing an increase in the weight of the stator core 91. The housing body 32 may also be configured as shown in FIG. 9A . Specifically, in FIG. 9A , a recess 32B recessed radially outward is formed on the inner surface of the housing body 32 shown in FIG. 7 , corresponding to the bulging portion 91T of the stator core 91. This allows the housing body 32 to be closer to the outer surface of the stator core 91, thereby reducing the outer dimensions of the housing body 32 and reducing the weight of the housing body 32. Furthermore, the housing body 32 may also be configured as shown in FIG. 9B . In FIG. 9B , a protrusion 32T bulging radially outward is formed on the housing body 32 to allow the bulging portion 91T of the stator core 91 to escape. In this case, the thickness of the housing body 32 between adjacent protrusions 32T, 32T in the circumferential direction can be made approximately equal to the thickness of the protrusion 32T, so the housing body 32 can be made even lighter than in Figure 9A.

[0054] 2, the sealing member 12 is disposed radially inward of the bolt 11 (between the housing 3 and the end plate 10), but the sealing member 12 may be disposed radially outward of the bolt 11 (or both radially inward and outward of the motor). Furthermore, if the sealing member covers the outer periphery of the bolt hole 10a and is disposed in a ring shape with a hole through which the shank of the bolt 11 can be inserted, the space required for disposing the sealing member can be reduced, thereby reducing the radial thickness of the housing and further reducing the weight. The components not described in FIGS. 6 and 7 are the same as those in FIG. 1, and are therefore denoted by the same reference numerals and will not be described again.

[0055] Alternatively, a configuration as shown in FIG. 8 may be used. That is, FIG. 8 illustrates a case where the flow passage 6 (stator cooling passage 61) shown in FIG. 1 also serves as a bolt through hole. This configuration has the advantage of being easier to manufacture than when the bolt through hole is formed separately from the flow passage 6. As in FIG. 6 , a threaded hole 323N is formed in the step portion 323 of the housing 3 (the right end portion in FIG. 8 ) to threadably engage the threaded portion 11N formed at the tip of the bolt 11 that passes through the flow passage 6. Although FIG. 8 illustrates one bolt 11, it is preferable to provide multiple bolts (two or more). Note that components not described in FIG. 8 are the same as those in FIG. 1, and are therefore denoted by the same reference numerals and will not be described again.

[0056] Furthermore, in the first to fourth embodiments, the housing 3 is made of a single metal material. However, a portion of the housing 3 including the step 323, which is positioned relative to the stator core 91 such that a force due to a difference in linear expansion may be generated, may be made of a material with a linear expansion coefficient different from that of the material constituting the stator core 91, and the remaining portions of the housing 3 may be made of a different material. In some cases, the housing 3 may be made of a synthetic resin. Furthermore, in the first to fourth embodiments, the stator core 91 is also made of a single metal material. However, a portion of the housing 3 including the step 323, which is positioned relative to the stator core 91 such that a force due to a difference in linear expansion may be generated, may be made of a material with a linear expansion coefficient different from that of the material constituting the housing. In other words, a portion of the housing 3 including the step 323 may be made of a material with a linear expansion coefficient different from that of the material constituting the stator core 91, and the remaining portions of the stator core 91 except for the one axial end portion may be made of a material different from that material.

[0057] The configurations and operations of the above-described embodiments are summarized below. The liquid-cooled motor 1 of the above-described embodiment (1) includes a housing 3, a rotor 8 that rotates about an axis X relative to the housing 3, a stator 9 that is fixed to the housing 3 and generates a magnetic force for the rotor 8 to rotate, the stator 9 having at least a portion formed of a material with a linear expansion coefficient different from that of the housing 3, a flow path 6 formed within the housing 3 through which a cooling liquid flows, an end plate 10 that is provided across end faces 322 a, 91 c of the housing 3 and the stator 9 in the direction of the axis X and is disposed facing the flow path 6, and a fastening member 11 that generates a fastening force in a direction that tightly contacts the end plate 10 with the housing 3 and the stator 9.

[0058] According to the present embodiment (1), the flow path 6 through which the cooling liquid flows is formed by arranging the end plate 10 across the end faces of the housing 3 and the stator 9 in the direction of the axis X. By fastening the end plate 10 to the housing 3 and the stator 9 with fastening members in a direction that brings the end plate 10 into close contact with the housing 3 and the stator 9, even if the housing 3 and the stator 9 are made of different materials, the fastening force applied to the end plate 10 prevents the cooling liquid from leaking from the flow path 6. This eliminates the need to increase the radial thickness of the motor 1, and can suppress an increase in the motor mass.

[0059] Furthermore, the liquid-cooled motor 1 of the present embodiment (2) may further include a partition wall 4 provided between the rotor 8 and the stator 9 along the direction of the axis X to partition the flow path 6 in the embodiment (1), the stator 9 having a coil 92, the stator 9 having coil slots 93 extending in the axial direction and holding the coils 92, the coil slots 93 having intra-slot spaces 15 extending over the entire axial length of the stator 9, and the intra-slot spaces 15 constituting a part of the flow path 6 through which the cooling liquid passes.

[0060] According to the above configuration, the flow paths through which the cooling liquid flows inside and outside the stator 9, that is, the flow path formed between the stator 9 and the housing 3, and the flow path formed in the slot space 15 can be combined into a single flow path 6.

[0061] Furthermore, the liquid-cooled motor of this embodiment (3) may be configured such that, in the embodiment (1) or (2), the flow path 6 has a buffer section 17 in which the cross-sectional area of ​​the cross section perpendicular to the direction in which the cooling liquid passes is enlarged.

[0062] According to the above configuration, the fluid resistance in the buffer portion 17 is small (low), so that the cooling liquid can flow relatively evenly through the flow paths with large (high) fluid resistance (for example, the flow paths within the coil slots 93).

[0063] Furthermore, the liquid-cooled motor of this embodiment (4) may be any of the embodiments (1) to (3) provided with a sealing member 12 between the housing 3 and the end plate 10 to prevent leakage of the cooling liquid.

[0064] According to the above configuration, even if a gap occurs between the housing 3 and the end plate 10 due to a difference in the linear expansion coefficient between the stator 9 and the housing 3 in the axial direction due to temperature changes, etc., the gap can be filled with the sealing member 12, thereby effectively preventing leakage of the cooling liquid.

[0065] Furthermore, in the liquid-cooled motor 1 of this embodiment (5), in any of the embodiments (1) to (4), the flow path 6 may be formed inside the housing 3 and facing the stator 9.

[0066] Furthermore, in the liquid-cooled motor 1 of this embodiment (6), in any of the embodiments (1) to (5), the stator 9 may be fixed by being sandwiched between the housing 3 and the end plate 10, so that the flow path 6 is formed surrounded by the stator 9, the housing 3, and the end plate 10.

[0067] Furthermore, the liquid-cooled motor 1 of this embodiment (7) may be configured in any of the embodiments (1) to (6) such that the fastening member 11 generates the fastening force in the direction of the axis X.

[0068] Furthermore, the liquid-cooled motor 1 of this embodiment (8) is any of the embodiments (1) to (7), in which the housing 3 comprises a housing main body 32 having a side wall portion at one end in the direction of the axis X and an opening at the other end, and a lid body 33 that closes the opening of the housing main body 32, and the lid body 33 is formed with an inlet-side through hole 10K and an outlet-side through hole 10A provided at a position different from the inlet-side through hole 10K, and the inlet-side through hole 10K is a portion through which a supply pipe 13 that supplies the cooling liquid from outside the motor to the flow path 6 passes, and the outlet-side through hole 10A is connected to the flow path 6 and may be a portion through which the cooling liquid that has passed through the flow path 6 is discharged to the outside of the motor.

[0069] Furthermore, the liquid-cooled motor 1 of this embodiment (9) may be configured in any of the embodiments (1) to (8) such that an end space 14 is formed between the end of the stator 9 in the direction of the axis X and the housing 3, and the housing 3 has a cutout portion 323K that connects the flow path 6 and the end space 14.

[0070] Furthermore, the liquid-cooled motor 1 of this embodiment (10) may be configured such that, in any of the embodiments (1) to (9), the fastening member 11 has a length that extends to both ends of the stator 9 in the direction of the axis X.

[0071] Furthermore, the liquid-cooled motor 1 of this embodiment (11) may be configured such that, in any of the embodiments (1) to (10), the stator 9 has a bulge portion 91T that protrudes radially outward.

[0072] Furthermore, the liquid-cooled motor 1 of this embodiment (12) may be configured such that, in the embodiment (11), the housing 3 has a recess 32B facing the bulge portion 91T radially outside the bulge portion 91T.

[0073] Furthermore, the liquid-cooled motor 1 of this embodiment (13) may be configured such that, in any of the embodiments (1) to (12), the housing 3 has an inlet IN and an outlet OUT for the cooling liquid, the inlet IN is connected to a guide pipe 103 that guides the cooling liquid supplied by a pump 102 from a storage section 101 that stores the cooling liquid provided externally, and the outlet OUT is connected to a discharge pipe 104 that returns the cooling liquid that has cooled the stator 9 to the storage section 101 via a heat exchanger 105.

[0074] As described above, according to this embodiment, the end plate 10 can be tightly attached to the housing 3 and the stator 9 using the fastening member 11, so that a liquid-cooled motor 1 can be provided that can suppress an increase in motor mass even if the housing 3 and the stator 9 are made of different materials.

[0075] 1...motor, 2...motor section, 3...casing, 4...partition wall, 5...rotating shaft, 6...flow path, 7A, 7B...bearings, 8...rotor, 9...stator, 10...end plate, 10A...through hole, 10B...outer surface, 10K...through hole, 10a...bolt hole, 11...bolt (fastening member), 11A...shaft section, 11N...threaded section, 12...sealing member, 13...oil supply port (oil supply pipe), 14...first space, 15...intra-slot space, 16...second space, 17...buffer section, 18...adhesive layer, 31...side wall section, 31A...through hole, 31a...end surface, 32...casing main body, 32A...radial inner surface, 32B...recess, 32T...protrusion, 33...lid body, 33A...through hole, 33B...discharge port, 33K...through hole, 33a...end surface, 61...stator cooling passage, 62...coil cooling passage, 91...stator core, 91T...bulge portion, 91a...inner surface, 91b...radial outer surface, 91c...axial left end surface, 92...coil, 92A...coil end portion, 93...coil slot, 101...storage portion (tank), 102...pump, 103...guiding pipe, 104...discharge pipe, 105...heat exchanger, 321...thin portion, 321A...inner surface, 322...thick portion, 322A...bolt through hole, 322M...groove, 322N...threaded portion, 322a...axial left end surface, 323...step portion, 323K...notch, 323N...screw hole, 323a...vertical surface, 323b...horizontal surface, IN...inlet, OUT...outlet, X...axis

Claims

1. A liquid-cooled motor comprising: a housing; a rotor that rotates about an axis with respect to the housing; a stator that is fixed to the housing and generates a magnetic force for the rotation with respect to the rotor, the stator being formed of a material having a different linear expansion coefficient from that of the housing at least in part; a flow path formed in the housing through which a cooling liquid passes; an end plate provided so as to extend across end faces of the housing and the stator in the direction of the axis and disposed facing the flow path; and a fastening member that generates a fastening force in a direction to bring the end plate into close contact with the housing and the stator.

2. Further comprising a partition wall provided along the direction of the axis between the rotor and the stator for partitioning the flow path, the stator having a coil, the stator comprising a coil slot that extends in the axial direction and holds the coil, the coil slot having a slot inner space that extends over the entire axial length of the stator, the slot inner space constituting a part of the flow path through which the cooling liquid passes, the liquid-cooled motor according to claim 1.

3. The liquid-cooled motor according to claim 1, wherein the flow path has a buffer portion in which a cross-sectional area of a cross-section orthogonal to the direction in which the cooling liquid passes is enlarged.

4. The liquid-cooled motor according to claim 1, further comprising a sealing member between the housing and the end plate for preventing leakage of the cooling liquid.

5. The liquid-cooled motor according to claim 1, wherein the flow path is formed facing the inside of the housing and the stator.

6. The liquid-cooled motor according to claim 1, wherein the stator is sandwiched and fixed between the housing and the end plate, and thus the flow path is formed surrounded by the stator, the housing, and the end plate.

7. The liquid-cooled motor according to claim 1, wherein the fastening member generates the fastening force in the direction of the axis.

8. The housing includes a housing body having a side wall portion at one end in the direction of the axis and an opening at the other end, and a lid body for closing the opening of the housing body. An inlet-side through hole and an outlet-side through hole provided at a position different from the inlet-side through hole are formed in the lid body. The inlet-side through hole is a portion through which a supply pipe for supplying the cooling liquid from outside the motor penetrates into the flow path. The outlet-side through hole communicates with the flow path and is a portion where the cooling liquid that has passed through the flow path is discharged to the outside of the motor. The liquid-cooled motor according to claim 1.

9. An end space is formed between an end portion of the stator in the direction of the axis and the housing. The housing has a notch portion that communicates the flow path and the end space. The liquid-cooled motor according to claim 1.

10. The fastening member has a length extending across both ends of the stator in the direction of the axis. The liquid-cooled motor according to claim 1.

11. The stator has a bulging portion that protrudes radially outward. The liquid-cooled motor according to claim 1.

12. The housing has a recess portion facing the bulging portion on the radially outer side of the bulging portion. The liquid-cooled motor according to claim 11.

13. The housing includes an inlet and an outlet for the cooling liquid. A guiding pipe for guiding the cooling liquid supplied by a pump from a storage portion provided outside for storing the cooling liquid is connected to the inlet. A discharging pipe for returning the cooling liquid that has cooled the stator to the storage portion via a heat exchanger is connected to the outlet. The liquid-cooled motor according to claim 1.

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