Motor

Abstract

The present subject matter provides an electric machine (100) comprising a stator (111), a rotor (113), a first end cap (114) and a cover (132). A first end cap (114) is thermally connected to the stator (111). The first end cap (114) includes an outer wall (115) and an end cap annular portion (116). The outer wall (115) is a first distance from the end cap annular portion (116) and forms a radially closed portion. The outer wall is provided with one or more ports (122, 123) to deliver coolant to the radially closed portion. The radially closed portion is covered by a base surface (120), where the base surface (120) is thermally connected to the stator (111) and the base surface (120) prevents leakage of the coolant to the stator (111).

Description

Technical Field

[0001] The present subject matter relates generally to electric machines, and particularly, but not exclusively, to electric machines such as electric motors. Background Art

[0002] Typically, electrical machines such as motors and generators are used to convert electrical energy into mechanical energy or vice versa, respectively. Electric motors produce linear or rotational force (torque) depending on the electrical input they receive. Typically, an electric motor consists of a rotor, a stator, one or more windings, and a commutator. The stator is usually the stationary part of the motor and consists of field magnets. Typically, the field magnets are either electromagnets consisting of wire windings around a ferromagnetic core, or multiple permanent magnets. The magnetic field generated passes through the armature of the rotor. The rotor is the moving part of the motor that turns the shaft to transmit mechanical power. The rotor is usually composed of conductors that can carry current applied by the stator magnetic field, forcing the shaft to rotate. Alternatively, some motors carry the field magnets and the stator holds the conductors. Some motors also include Hall effect sensors on the stator of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The detailed description is described with reference to an embodiment of a motor assembly for a vehicle and the accompanying drawings. The same numerals are used throughout the drawings to refer to the same features and components.

[0004] Figure 1 An exploded perspective view of the electric machine is shown.

[0005] Figure 2 A perspective view of a stator of an electric machine is shown.

[0006] Figure 3 A perspective view of a first end cap of an electric machine is shown.

[0007] Figure 4 A perspective view of a cover of the electric machine is shown.

[0008] Figure 5 A perspective view of a second end cap of the electric machine is shown. DETAILED DESCRIPTION

[0009] Typically, a motor or generator generates a lot of heat during the process of converting electrical energy to mechanical energy or mechanical energy to electrical energy. One or more windings are usually used in the stator of the motor to generate the magnetic field. In order to produce torque, current is forced through the motor windings, causing the temperature of the motor windings to steadily increase. In addition, as the temperature of the motor windings increases, the resistance of the windings also increases. The motor winding resistance (Rmt) is one of the main sources of heat generation.

[0010] In order to check the heat or temperature rise within the electric motor, various thermal management techniques are used. The two most prominent thermal management techniques are air cooling of the electric motor and liquid cooling of the electric motor. In air cooling of the electric motor, surface fins are provided on the electric motor, which dissipate heat through natural convection or forced convection (for example, by a fan mounted on the motor shaft). However, due to layout space limitations, forced cooling mechanisms are generally undesirable in vehicles. This is particularly challenging in compact two- or three-wheeled vehicles, which, unlike four-wheeled vehicles, may not have enough space, and adding a forced cooling system would undesirably increase the weight and cost of the entire vehicle. Such vehicles typically have a compact powertrain, so air cooling of the electric motor is achieved through multiple radial fins around the electric motor.

[0011] Another method of achieving effective cooling of the electric motor is liquid cooling of the electric motor. In the configuration of a liquid cooling system, features such as pumps, radiators, and hoses are used. The heat of the electric motor is removed by the flow of coolant and discharged or dissipated through the radiator.

[0012] In the prior art, a plurality of pipes through which coolant passes are provided in the stator of the electric motor. The coolant passes through the frame of the stator in axial partitions. In another prior art, tangential partitions are created on the stator frame to allow coolant to pass through them.

[0013] In another prior art, the motor housing has a cooling channel connected to an external coolant supply source. The rotor is provided with an injection port facing the stator, and the rotor has a shaft coolant path connected to the cooling channel on the motor housing. The stator core is cooled by a cooling jacket, and direct internal cooling is also applied to the stator winding by fixed-point injection of the cooling jacket and rotating injection of the magnetic isolation plate. This results in cooling the stator winding by forced liquid cooling.

[0014] In another prior art, a liquid cooling system includes a manifold extending above the stator, which receives liquid under pressure and has openings that direct jets of liquid to the ends of the stator and rotor. In addition, trays are provided on the stator and rotor that take the liquid coolant from the manifold injectors and distribute the gravity-fed coolant to other parts. In this topology, the rotor and stator are directly cooled by the liquid.

[0015] In existing liquid cooling systems, the coolant actively contacts the stator windings. This interaction limits the operation of the stator windings. The coolant that reaches the stator can negatively affect the life of the stator windings. In addition, when the coolant reaches the stator windings, the user cannot use different kinds of coolants in the motor. In this cooling system, only a single type of coolant can be used. Any change in the coolant can damage the stator windings. In this cooling system, any cleaning of the cooling channels requires opening the entire motor. In addition, in the event that any impurities pass through the coolant, these impurities can reach the stator windings or the rotor, which can seriously damage the operation of the motor.

[0016] In addition, in other known or existing liquid cooling systems, the coolant passes through the frame of the motor / stator. This cooling system requires modification of the motor design. In addition, the modification of the stator design limits the motor to a liquid cooling mechanism. The modification of the motor design to the external frame will limit the motor to cooling only by coolant. In this motor, an air cooling system is not feasible because the outer surface of the motor cannot accommodate both the fins and the liquid cooling chamber at the same time. In addition, if a coolant chamber and fins are provided, the cooling will be limited because the fins for air cooling will be insufficient. In addition, in the case of only a liquid cooling system, the cooling of the motor is limited. The coolant only reaches a limited hot area of ​​the motor. In addition, the motor with a manifold complicates the motor design and limits the cooling of the motor to liquid cooling. In designs that provide both air cooling and liquid cooling, the air cooling fins are not utilized to the maximum extent due to design constraints. The motor frame cannot accommodate fins as well as a coolant chamber or a coolant manifold.

[0017] Therefore, there is a need to provide an improved electric motor cooling system that is capable of cooling most of the hot areas of the electric motor while overcoming all of the previously mentioned problems and other problems of the known art. More specifically, sufficient cooling is to be provided for the hot areas where the highest heat is generated. In addition, damage to the stator windings due to liquid coolant needs to be prevented. In addition, the electric motor should be configured to accommodate a variety of coolants. In addition, the electric motor should be configured to fully optimize air cooling and liquid cooling systems.

[0018] In one aspect of the present invention, an improved electric machine is disclosed, the electric machine comprising: a stator, a rotor, a first end cap and a cover. The rotor is coupled to the stator. The first end cap is thermally connected to the stator. The cover closes the first end cap from one side of the electric machine. The first end cap comprises: an outer wall and an end cap annular portion. The end cap annular portion is spaced a first distance from the outer wall to form a radially closed portion. The radially closed portion is covered by a base surface, which is thermally connected to the stator. The radially closed surface receives coolant from the outer wall, and the base surface is configured to prevent any leakage of the coolant.

[0019] The summary provided above explains the basic features of the subject matter and does not limit the scope of the invention. The nature and other characteristic features of the subject matter will become more apparent from the following description made with reference to the accompanying drawings.

[0020] An exemplary embodiment of the pedal assembly features detailed according to the present subject will be described below with reference to the accompanying drawings. Various aspects of the different embodiments of the present subject will become discernible from the following description. Specifically, the following description provides a convenient description for implementing an exemplary embodiment of the present subject. In addition, it should be noted that, unless otherwise specified, the terms "upper", "lower", "right", "left", "front", "forward", "backward", "downward", "upward", "top", "bottom" and similar terms are used in this article based on the vehicle state shown or the vehicle standing state with the driver sitting on it. In addition, the vertical axis refers to the upper and lower axis relative to the vehicle, defining the vertical direction of the vehicle; and the transverse axis refers to the side-to-side axis or the left-right axis relative to the vehicle, defining the transverse direction of the vehicle. In addition, the longitudinal axis refers to the longitudinal direction relative to the front-to-back axis of the vehicle, defining the vehicle. In addition, it should be understood that the words and terms used herein are used for descriptive purposes only and should not be regarded as limiting.

[0021] The present subject matter is further described with reference to the accompanying drawings. It should be noted that the specification and the accompanying drawings illustrate only the principles of the present subject matter. Although not explicitly described or illustrated herein, various arrangements that encompass the principles of the present subject matter may be designed. In addition, all statements of the principles, aspects, and examples of the present subject matter and their specific examples herein are intended to encompass their equivalents.

[0022] Figure 1 An exploded perspective view of a motor 100 according to an exemplary embodiment of the present invention is shown. The motor 100 includes a stator 111, a rotor 113, a first end cover 114, a cover 132, and a second end cover 127. The stator 111 is a stationary part, the rotor 113 is a moving part, and the two are electromagnetically coupled to each other. The stator 111 is enclosed in a housing 110, and the first end cover 114 covers a first side of the stator 111 and the rotor 113. The first end cover 114 is locked to the housing 110 from one side, and the second end cover 127 is locked to the housing 110 on the opposite side of the housing 110. In addition, the cover 132 is fixed to the first end cover 114 and the housing 110 through a plurality of mounting holes (130, 131), thereby covering the first end cover 114.

[0023] In an embodiment, the housing 110 includes one or more fins 128 on an outer surface. The one or more fins 128 are configured to cool the stator 111 through an air cooling mechanism.

[0024] Figure 2A perspective view of a stator 111 is shown. The stator 111 comprises a cylindrical surface (111') on the outside of the stator 111 and transverse end side surfaces (111s) on each side of the cylinder. One or more stator teeth 111A are provided on an inner cylindrical surface (not shown) of the stator 111. The teeth 111A are covered by one or more field windings 112, and when current is passed through the windings, the stator becomes a field magnet or electromagnet.

[0025] Figure 3 A perspective view of the first end cap 114 is shown. The first end cap 114 includes a base (120), an annular outer wall 115 and an end cap inner annular portion 116, which is coaxially arranged with the outer wall 115 relative to the rotor axis R-R'. The annular outer wall 115 and the end cap inner annular portion 116 protrude orthogonally to the base 120, and the protrusion is along the rotor axis R-R'. The outer peripheral annular surface (115') of the outer wall 115 is provided with one or more open ports 122, 123, which are inlet ports 122 and outlet ports 123 for flowing a cooling medium. The end cap inner annular portion 116 is spaced apart from the outer wall 115 by a first radial distance (a). In addition, the outer wall 115, the end cap inner annular portion 116 and the base 120 together form a radial closed channel 120', which receives coolant from one or more ports 122, 123. The radial closed channel 120' is covered by the base 120, one end surface of the base 120 is configured to be in thermal contact with the coolant, and the other end surface of the base 120 is in thermal contact with the teeth 111A and the lateral end surface 111s of the stator 111 for transferring heat from the stator 111 to the base 120 by conduction.

[0026] Furthermore, in an embodiment, the outer wall 115 includes one or more locking portions 119 having one or more outer wall locking openings 119 ′ for locking the first end cap 114 to the housing 110 .

[0027] In an embodiment, the end cover inner annular portion 116 is formed in a middle region of the first end cover 114 and has a hollow portion at the center of the end cover inner annular portion 116. The rotor axis RR' passes through the hollow portion at the center of the end cover inner annular portion 116. In addition, the end cover inner annular portion 116 includes a radial surface 118. The radial surface 118 forms an outer boundary of the end cover inner annular portion 116. In addition, the radial surface 118 and the outer wall 115 form a radial closed channel 120', which is configured to receive a cooling fluid from one or more ports 122, 123.

[0028] In another additional embodiment, the base surface 120 includes one or more protrusions 121. The one or more protrusions 121 are uniformly shaped baffles. In another embodiment, the one or more protrusions 121 are non-uniformly shaped baffles, wherein the baffles can enhance heat conduction to the cooling medium.

[0029] Figure 4 A perspective view of the lid 32 is shown. The lid 32 includes an inner planar base 126 and a lid annular wall portion 125 protruding from the base 126. The lid annular portion 125 includes a radial annular surface 125A that fits tightly to the radial surface 118 of the end cap inner portion 116 to serve as a guide for positioning the lid 132. In addition, the lid 132 is provided with one or more lid locking portions 124 having one or more lid locking openings 124' that are aligned with the one or more locking portions 119 of the end cap 114 and attached by suitable locking means to seal the closure portion 120' between the outer wall 115 and the inner annular portion 116.

[0030] Figure 5 A second end cover 127 is shown, which covers the housing 110 and the stator 111 from a side opposite to the second side of the first end cover 114 and the stator 111. The second end cover 127 includes one or more second locking portions 130, which have one or more second end cover locking openings 130', which enable the second end cover 127 to be locked with the housing 110. The second end cover 127 is provided with a second annular protruding wall portion 131 in a middle area of ​​the second end cover 127. In addition, the second cover 127 includes an inner annular plane 129 adjacent to the annular portion 131. In an embodiment, the second end cover 127 includes one or more Hall sensors for determining the annular position of one or more teeth 111A of the stator 111.

[0031] In an embodiment of the present subject matter, the stator 111 is a stationary electrical component configured to have one or more teeth 111A inside the stator 111. The rotor 113 is coaxially located within the stator 111 and is mounted to the shaft of the motor 100 along the rotor axis R-R'. The rotor 113 rotates due to the magnetic interaction between the stator 111 and the rotor 113. The rotation of the rotor 113 in turn rotates the shaft of the motor 100. In the motor 100, all electrical components generate heat. However, the stator 111 and the rotor 113 are the main heat-generating elements. In order to cool the main heat-generating elements, the present subject matter provides a liquid cooling mechanism that can effectively cool the stator 111 and the rotor 113. According to an embodiment, when air cooling passes through the fins, the liquid cooling can be controlled by one or more controllers capable of actuating one or more ports (122, 123).

[0032] According to an exemplary embodiment of the present subject matter, the first end cover 114 receives coolant from the inlet port 122, which is received by the radially closed passage 120' defined by the base 120. One end surface of the base 120 is in thermal contact with the teeth 112 of the stator 111. In addition, the base 120 is configured to prevent coolant from leaking from the radially closed passage 120' to the field magnets 112. In this configuration, the base 120 acts as a partition wall between the radially closed portion 120' and the field winding 112. The thermal contact between the base 120 and the stator 111 ensures that the heat generated by the field winding 112 is effectively conducted to the base 120, which is then cooled by the coolant in the radially closed portion 120'. The base 120 also ensures that the heat is confined to the stator 111 and is not transferred to the end of the motor 100. In addition, the base 120 provides a larger effective surface area for the coolant, thereby ensuring that the entire area is in thermal contact and the base 120 is effectively cooled. The coolant passes out of the radially enclosed portion through the outlet port 123 .

[0033] In another embodiment, the base surface 120 is provided with one or more protrusions 121, which are also referred to as one or more baffles. According to the configuration, the one or more protrusions 121 collect heat from the stator 111, which is then effectively cooled by the coolant. When the heat is confined within a specified cross-sectional area (which is an area increased due to the baffles), the coolant works more effectively in the one or more protrusions 121. In addition, the one or more protrusions 121 provide effective flow for the coolant. The one or more protrusions 121 ensure continuous flow of the coolant in the radially enclosed portion and minimize the formation of vortices.

[0034] In an embodiment, the shape of the one or more protrusions 121 is uniform so that vortices are not formed during the continuous flow of the coolant and the flow of the coolant is uniform.

[0035] In another embodiment, the shape of one or more protrusions 121 is non-uniform, thereby generating minimal eddy currents. In this configuration, the flow of the coolant is generally non-uniform, however, the cooling efficiency is not affected due to the continuous movement of the coolant.

[0036] The motor 100 according to the present invention is cooled by a combination of a liquid cooling mechanism and an air cooling mechanism. In this configuration, the housing 100 is provided with one or more fins 128, which ensure continuous air cooling of the stator 111. In addition, liquid cooling is provided by the coolant in the radially closed portion 120' and the base 120, and the base 120 serves as a partition wall between the field winding 112 of the stator 111 and the coolant. In this configuration, liquid cooling can be enabled or controlled as needed. In the case where the motor 100 is only air-cooled, the inlet port 122 and the outlet port 123 can be blocked or sealed. However, in the case where it is desired to cool the motor 100 by both air cooling and liquid cooling, the inlet port 122 and the outlet port 123 can be released.

[0037] Although the subject matter has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. It should be understood that the appended claims are not necessarily limited to the features described herein. Rather, these features are disclosed as embodiments of the subject matter.

[0038] Reference numerals list

[0039] 100: Motor 120': Closed channel

[0040] 110: Shell 121: Protruding part

[0041] 111: Stator 20 122: Inlet port

[0042] 111': Stator cylindrical surface 123: Outlet port

[0043] 111A: stator teeth 124: cover locking part

[0044] 111s: Transverse end surface of stator 124': Cover locking opening

[0045] 112: Field winding 125: Cover annular wall portion

[0046] 113: Rotor 25 125A: Radial annular surface

[0047] 114: first end cap 126: flat base

[0048] 115: Outer wall 127: Second end cover

[0049] 115': Circumferential annular surface 128: Fins

[0050] 116: Inner annular portion of the end cap 129: Inner annular plane

[0051] 118: Radial surface 30 130: Second locking portion

[0052] 119: Locking portion 130': Second end cover locking opening

[0053] 119': outer wall locking opening 131: second annular wall portion

[0054] 120: base 132: cover

Claims

1. A motor (100), comprising: stator (111); a rotor (131) electrically coupled to the stator (111); a first end cover (114), the first end cover (114) being in thermal contact with the stator (111) on a first side of the stator (111); and a cover (132) attached to the first end cover (114) from one side of the motor (100) to seal a coolant within the first end cover (114); The first end cover (114) comprises: an outer wall (115) having one or more ports (122, 123) for receiving the coolant; an end cap annular portion (116), the end cap annular portion (116) and the outer wall (115) being spaced apart by a first predetermined distance "a"; The base (120), the outer wall (115) and the end cover annular portion (116) protrude orthogonally to the base (120), thereby forming a radial closed channel 120'; wherein The radial closed channel 120' is in thermal contact with the stator (111) to transfer heat to the base (120); The radially closed channel 120' is configured to receive the coolant to extract heat from the base (120) to cool the stator (111).

2. The electric machine (100) according to claim 1, wherein: The end cover annular portion (116) has a radial surface (118), and the cover (132) includes a cover annular wall portion (125); wherein the cover annular wall portion (125) is tightly abutted against the radial surface (118) of the end cover annular portion (116).

3. The electric machine (100) according to claim 1, wherein: The base (120) includes one or more protruding portions (121).

4. The electric machine (100) according to claim 3, wherein: The one or more protrusions (121) are baffles of uniform shape.

5. The electric machine (100) according to claim 3, wherein: The one or more protrusions (121) are baffles of uneven shape.

6. The electric machine (100) according to claim 1, wherein: The outer wall (115) has one or more locking portions (119), and the locking portions (119) are configured to be attached to a housing (110) of the stator (111).

7. The electric machine (100) according to claim 1, wherein: The one or more ports (122, 123) include an inlet port (122) and an outlet port (123).

8. The electric machine (100) according to claim 1, wherein: The lid (132) has one or more lid locking portions (124).

9. The electric machine (100) according to claim 1, wherein: The stator (111) is connected to a second end cover (127) at a second side of the stator (111); wherein the second end cover (127) covers the stator (111) from an opposite side of the first end cover (114).

10. The electric machine (100) according to claim 1, wherein: The stator (111) is configured to be air-cooled via a plurality of fins (128) on a housing (110) of the stator (111).

11. The electric machine (100) according to claim 1, wherein: The stator (111) is configured to have one or more teeth (111A) on an inner surface (not shown) of the stator (111), and the one or more teeth (111A) are covered by one or more field windings (112).

12. The electric machine (100) according to claim 1, wherein: The opening and closing of the one or more ports (122, 123) are electronically controlled by one or more controllers.

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