Drive components with integrated cooling

Abstract

A drive assembly for an electric vehicle includes an electric motor having a stator, the stator defining a stator duct. The drive assembly also includes a housing, the housing defining a gear chamber and a heat chamber fluidly separated from the gear chamber. The drive assembly also includes a cooling conduit disposed in the heat chamber. The electric motor is coupled to the housing and disposed in the gear chamber, and a rotor is disposed adjacent to the heat chamber. One of the cooling conduit and the heat chamber may be fluidly coupled to the stator duct to transfer thermal energy therebetween.

Description

Background Art

[0001] There is a growing need to reduce or eliminate the emissions generated by vehicles during operation. Vehicle manufacturers have increasingly turned to hybrid and all-electric propulsion systems to reduce vehicle emissions and improve efficiency. Typically, the electric motor is integrated into a drive assembly that is positioned near the vehicle's drive wheels.

[0002] Therefore, there is a need to provide a drive assembly that provides enhanced cooling for an electric motor enclosed within a gearbox housing. Summary of the invention

[0003] A drive assembly for an electric vehicle, the drive assembly comprising an electric motor having a motor shaft defining a motor axis and comprising one or more rotors coupled to the motor shaft. The electric motor may also include a stator arranged about the motor axis, the stator defining a stator conduit having a conduit inlet and a conduit outlet. The drive assembly may also include a cooling conduit having a conduit inlet and a conduit outlet fluidly coupled to the conduit outlet. The drive assembly may also include a pump fluidly coupled to the conduit outlet and the conduit inlet. The stator conduit, the cooling conduit, and the pump cooperate to define a stator cooling circuit. The drive assembly may also include a gear arrangement operably engaged with the electric motor for transmitting the rotation of the motor shaft to one or more wheels of the electric vehicle. The drive assembly may also include a housing defining a gear chamber and a heat chamber fluidly separated from the gear chamber. The heat chamber may contain a second heat transfer fluid. The electric motor may be coupled to the housing so that the rotor is arranged adjacent to the heat chamber and the gear arrangement is arranged in the gear chamber. The cooling conduit may be disposed in the heat chamber for transferring heat energy between a first heat transfer fluid and a second heat transfer fluid. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Advantages of the present disclosure will be readily appreciated as they may be better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings.

[0005] Figure 1 is an environmental view of an electric vehicle showing a drive assembly coupled thereto for transmitting rotation to one or more wheels of the electric vehicle.

[0006] Figure 2 yes Figure 1 A partial perspective view of an electric vehicle chassis with one of the wheels removed to show the drive shaft and brake assembly and the four drive assemblies.

[0007] Figure 3 It is based on the first construction Figure 2 A perspective view of one of the drive assemblies of the embodiment of the present invention, showing the outer side of the housing, with a broken line portion of the housing showing the heat chamber and cooling duct defined by the housing.

[0008] Figure 4 is a partial cross-sectional view of one side of the housing showing the heat chamber and cooling ducts.

[0009] Figure 5 is an exploded perspective view of the drive assembly illustrating a heat chamber, a gear chamber further defined in the housing, a motor, and a gear arrangement operably engaged with the gear arrangement.

[0010] Figure 6 yes Figure 5 An exploded view of the housing and part of the motor, showing the cooling ducts and pump.

[0011] Fig. 7A is along Figure 4 A cross-sectional view of the drive assembly taken along line 7-7 in FIG. 1 shows the heat chamber, gear chamber and stator of the motor.

[0012] Figure 7B yes Fig. 7A Magnified detailed view of a portion of.

[0013] Figure 8 is a perspective, partially cut-away view of a cooling duct and a stator of an electric machine according to a first configuration.

[0014] Fig. 9 is a partial cross-sectional view of one side of the housing showing the heat chamber and cooling conduits according to a second configuration of the drive assembly.

[0015] Fig.10 yes Fig. 9 Exploded view of the housing and parts of the motor, showing the cooling ducts and pump.

[0016] Fig.11 is a perspective, partially cut-away view of a cooling duct and a stator of an electric machine according to a second configuration. DETAILED DESCRIPTION

[0017] Referring to the drawings, wherein like reference numerals refer to like parts throughout the several views, the present disclosure includes a vehicle 30 having a chassis 32 supported on one or more wheels 34 capable of propelling the vehicle 30. The chassis 32 defines a centerline or longitudinal axis A3 that is generally parallel to the direction of travel of the vehicle 30. Figure 1The vehicle 30 shown in FIG. 1 is configured as a vocational truck that can be used in different applications, such as a delivery truck, a passenger car, a highway transport tractor for trailer towing, and other assembly applications. In order to provide the vehicle 30 with an increased payload capacity, the chassis 32 can be configured in a tandem configuration with two axles 36 for propelling the vehicle 30. More specifically, the chassis 32 includes two frame rails 38, each extending parallel to the longitudinal axis A3 between the front and rear of the vehicle 30. Near the rear of the vehicle 30, the axles 36 can be coupled to the frame rails 38 and spaced longitudinally from each other. The chassis 32 can be configured for "single wheel" applications (not shown) and "two wheel" applications. In the "single wheel" application, a single wheel is coupled to each lateral side of the vehicle 30. Similarly, in the "two wheel" application, the wheels 34 are arranged in pairs on each lateral side of the vehicle 30. Vehicles that require increased payload or towing capacity are an example where the "two wheel" configuration may be preferred. Because these vehicles are intended to be adapted to a variety of uses with specific requirements, the chassis 32 and frame rails 38 are adaptable so that the number of axles 36 and the number of wheels 34 are best suited for a specific use. This can include the use of tandem axles 36 having one two-wheel axle and one single-wheel axle. In addition, one of the axles 36 can be selectively moved relative to the chassis 32 to a raised position, wherein the wheels 34 are spaced apart from contact with the ground when the vehicle 30 is operating unloaded, to improve efficiency.

[0018] Now turn to Figure 2 The chassis 32 may also include suspension components, such as springs 40 or dampers 42, to optimize the performance of the vehicle 30 during operation. The suspension components movably couple the axle 36 to the frame rails 38 to maintain contact between the wheels 34 and the ground. The suspension components allow the axle 36 to move relative to the frame rails 38 and push the wheels 36 toward the ground when the vehicle 30 encounters imperfections in the ground. More specifically, the springs 40 and dampers 42 absorb the movement of the axle 36 and improve the ride quality. The vehicle 30 may also include brake components, such as cylinders, brake calipers 44, brake rotors, brake drums, brake hoses, etc., which cooperate to slow down and / or stop the vehicle 30. The brake components may be coupled to the axle 36 and / or the frame rails 38, as will be discussed in further detail below.

[0019] Typically, the vehicle 30 is propelled by transferring kinetic power to one or more wheels 34 in contact with the ground. To this end, a drive assembly 100 capable of rotating the wheels 34 may be coupled to the axle 36. In the case of an electric vehicle 30, such as Figure 1 and Figure 2As shown, the drive assembly 100 transfers the rotation of the motor to the wheels 34. Here, each axle 36 may include two drive assemblies 100 coupled to the bridge portion 46 and disposed on opposite lateral sides of the vehicle 30, wherein each drive assembly 100 provides rotation to a pair of wheels 34.

[0020] According to the first construction, Figure 3 5 shows one of the drive assemblies 100 removed from the axle 36 and details of the cooling system, as will be discussed in further detail below. The drive assembly 100 generally includes at least one motor 106 and a gear arrangement 108, each of which is disposed in a housing 104. During operation, the drive assembly 100 generates heat primarily through friction in the gear arrangement 108 and current flowing through the motor 106. The performance of the motor 106 can be improved by reducing the excess heat generated during operation. To this end, the drive assembly 100 also includes a cooling conduit 196 having a conduit inlet 198 and a conduit outlet 200. The cooling conduit 196 is disposed in a heat chamber 154 defined by the housing 104. As will be discussed below, the cooling conduit 196 is configured to transfer thermal energy between two fluids within the drive assembly 100. The heat chamber 154 is configured to absorb thermal energy from the cooling conduit 196, the gear chamber 152, the motor 104, the lubricant, and the brake components (e.g., the brake caliper 44) to transfer away from the drive assembly 100, thereby reducing the temperature.

[0021] The motor 106 is coupled to the housing 104 and is operably engaged with the gear arrangement 108 to transmit power to the wheels 34. The motor 106 includes a stator 130, rotors 132A, 132B, and a motor shaft 134 coupled to the rotors 132A, 132B. The rotors 132A, 132B and the motor shaft 134 are supported to rotate relative to the stator 130 about a motor axis A1 defined by the motor shaft 134. An output pinion 136 is coupled to the motor shaft 134 to engage with the gear arrangement 108. The gear arrangement 108 generally includes a series of gears and shafts that are supported to rotate within the housing 104.

[0022] The drive assembly 100 may also include a wheel end 105 coupled to the housing 104 and extending toward the wheel 34 to rotatably support the wheel 34. The wheel end 105 may include an axle shaft (not shown) that engages with the gear arrangement 108 and is rotatably coupled to the wheel 34 to transfer rotation therebetween. The housing 104 and the wheel end 105 may be constructed and coupled in various ways, such as using fasteners to couple the wheel end 105 to the housing. In alternative embodiments, the wheel end 105 may be integrally formed with the housing 104.

[0023] As described above, the gear arrangement 108 may include a series of gears and shafts, such as an idler shaft 110, an intermediate shaft 112, and an output shaft 114 defining a drive axis A2. Each shaft is supported by a bearing for rotation within the housing 104; an idler bearing 140 supports the idler shaft 110, an intermediate bearing 142 supports the intermediate shaft 112, and an output bearing 144 supports the output shaft 114. Bearings 140, 142, 144 may be used to reduce friction between the rotating components of the gear arrangement 108. Depending on the requirements of the application, various types of bearings may be used, such as journal (sliding) bearings, roller bearings, ball bearings, etc. Friction may be further reduced by using a lubricant such as gear oil. Lubricants are supplied to contact surfaces between components such as gear teeth and bearings 140, 142, 144 to prevent wear and reduce heat generated by friction. In addition to reducing the amount of heat generated, lubricants cool components of the drive assembly 100 by transferring thermal energy away from heat generating sources.

[0024] Power is transferred from the motor 106 to the wheels 34 via the gear arrangement 108. Figure 5 In the illustrated gear arrangement 108, the motor 106 can drive an idler shaft 110, which in turn can drive an intermediate shaft 112, which can further drive an output shaft 114. The shafts are driven by rotating engagement gears of various tooth counts to convert torque in one or more ratios. More specifically, the idler shaft 110 supports an idler gear 116 and an idler pinion 118; the intermediate shaft 112 supports an intermediate gear 120, a first intermediate pinion 122, and a second intermediate pinion 124; and the output shaft 114 supports a first output gear 126 and a second output gear 128.

[0025] Continue to refer Figure 5 , the gear arrangement 108 is generally configured such that the pinion(s) of one shaft engages the corresponding gear(s) of the adjacent shaft. Specifically, the idler gear 116 engages with the output pinion 136 to rotate the idler shaft 110 and the idler pinion 118. The idler pinion 118 engages with the intermediate gear 120 to rotate the intermediate shaft 112, the first intermediate pinion 122 and the second intermediate pinion 124. The first intermediate pinion 122 and the second intermediate pinion 124 engage the respective first output gear 126 and the second output gear 128 to rotate the output shaft 114. More specifically, the first output gear 126 engages with the first intermediate pinion 12, and the second output gear 128 engages with the second intermediate pinion 124.

[0026] In order to improve the starting and speed performance of the vehicle 30, the gear arrangement 108 is implemented as a dual-speed reduction, which can be selectively switched between a first ratio and a second ratio. The first ratio corresponds to the pairing of the first output gear 126 and the first intermediate pinion 122. Similarly, the second ratio corresponds to the pairing of the second output gear 128 and the second intermediate pinion 124. To this end, the gear arrangement 108 can include a shift assembly 138, which is operable to selectively engage the first ratio and the second ratio. The operation of the shift assembly 138 moves a shift fork (not shown) to rotationally couple and / or separate the first output gear 126 and the second output gear 128 from the output shaft 114. When the first output gear 126 is rotationally coupled to the output shaft 114, torque and rotation can be transmitted through the gear arrangement 108 at a first ratio, and when the second output gear 128 is rotationally coupled to the output shaft 114, torque and rotation can be transmitted through the gear arrangement 108 at a second ratio.

[0027] Referring again to the housing 104, the gear arrangement 108 is disposed in an interior 146 defined in the housing 104. The housing 104 may include a first body 148 and a second body 150 coupled to the first body 148 to define the interior 146. The first body 148 and the second body 150 may be manufactured from a variety of known materials using processes suitable for the selected materials. For example, an aluminum alloy that has been formed using a die casting process may be used.

[0028] The interior 146 may include a gear chamber 152 and a heat chamber 154. In other words, the housing 104 defines the gear chamber 152 and the heat chamber 154, wherein the heat chamber 154 is fluidly separated from the gear chamber 152. The gear chamber 152 and the heat chamber 154 are each defined by the housing 104 and are arranged such that there is no fluid communication therebetween. The first body 148 and the second body 150 cooperate to define the gear chamber 152. At least a portion of the gear chamber 152 may be defined by the first body 148 and the second body 150, such that the gear chamber 152 is substantially enclosed by coupling the second body 150 to the first body 148. The second body 150 may at least partially define the gear chamber 152 so as to allow the gear arrangement 108 to be disposed within the first body 148 and the second body 150 when the drive assembly 100 is assembled.

[0029] The motor 106 is disposed in the gear chamber 152, wherein the motor axis A1 is spaced apart from the drive axis A2. The motor axis A1 and the drive axis A2 are generally oriented perpendicular to the longitudinal axis A3 of the vehicle 30, and therefore, the motor axis A1 is spaced apart from the drive axis A2 along the longitudinal axis A3. The motor 106 and the output shaft 114 are therefore spaced apart from each other along the longitudinal axis A3. The spaced arrangement of the motor 106 and the output shaft 114 defines two corresponding sides of the housing 104, namely the motor side 158 and the output side 160. Similarly, the housing 104 defines an outboard side 162 and an inboard side 164 based on a relative distance from the longitudinal axis A3 or the centerline of the vehicle. The inboard side 164 generally faces the longitudinal axis A3 and is closer to the longitudinal axis A3 than the outboard side 162. In contrast, the outboard side 162 generally faces away from the longitudinal axis A3 and is further away from the longitudinal axis A3 than the inboard side 164.

[0030] As described above, the interior 146 may include a heat chamber 154 that is fluidly separated from the gear chamber 152. The heat chamber 154 is defined in the housing 104 and is disposed adjacent to the rotor 132A of the motor 106. More specifically, the heat chamber 154 is defined in the first body 148 and is disposed on the outward side 162 of the outward rotor 132A. The heat chamber 154 may have a generally cylindrical volume aligned with the motor axis A1, and may also have a diameter similar to the diameter of the motor 106.

[0031] The gear chamber 152 may also include a sump 156 defined in the housing 104 to store lubricant for the gear arrangement 108. The sump 156 is positioned at the lowest point of the gear chamber 152 to collect lubricant that has been dispersed throughout the gear chamber 152. The dispersed lubricant is drained into the sump 156 for cooling and degassing. Figure 5 In the illustrated housing 104, the reservoir 156 is disposed proximate the motor side 158 of the housing 104 and below the motor 106. To prevent portions of the gear arrangement 108 from protruding into the reservoir 156 and contacting the free surface of the lubricant disposed therein, a windage wall 166 is disposed above the reservoir 156 and coupled to the housing 104. Additionally, a slosh baffle 168 may protrude from the windage wall 166 into the reservoir 156 to reduce the ability of the lubricant to flow in response to braking, acceleration, and cornering of the vehicle 30. When the slosh baffle 168 contacts the lubricant, the slosh baffle acts as a heat sink to transfer heat from the lubricant to the housing 104 and the thermal chamber 154.

[0032] The details of the motor 106 are Fig. 7A Specifically, Fig. 7AThe axial arrangement of the motor 106 within the gear chamber 152 is shown. The motor 106 is axially spaced from the heat chamber 154 toward the inboard side 164 of the housing 104. The motor 106 is axially spaced such that a gap 262 is defined between the first rotor 132A and the heat chamber 154, thereby allowing lubricant disposed in the gear chamber 152 to enter. The stator 130 is coupled to the housing 104 between the rotors 132A, 132B, which in turn are coupled to the motor shaft 134 for rotation relative to the stator 130. The rotors 132A, 132B are disposed in the gear chamber 152 and are axially spaced from the stator 130 along the motor axis A1.

[0033] Each rotor 132A, 132B has a generally annular shape with a motor shaft 134 extending through each rotor 132A, 132B and coupled with a series of fasteners 184. In addition, each rotor 132A, 132B includes a series of magnets 186 radially arranged about the motor axis A1 with the magnetic poles oriented parallel to the motor axis A1.

[0034] The motor shaft 134 extends between the first body 148 and the second body 150 in the motor side 158 of the housing 104. Two motor bearings 218A, 218B support the motor shaft 134 for rotation about the motor axis A1, the first motor bearing 218A in the first body 148 and the second motor bearing 218B in the second body 150. As described above, the output pinion 136 and the rotors 132A, 132B are each coupled to the motor shaft 134. The output pinion 136 may be arranged adjacent to the second bearing 218B, and the rotors 132A, 132B may be arranged between the output pinion 136 and the first bearing 218A. In order to couple the rotors 132A, 132B to the motor shaft 134, the motor shaft 134 may have a shoulder portion 220 arranged adjacent to the output pinion 136. The motor shaft 134 may include a rotor hub 222 for spacing the rotors 132A, 132B, abutting the shoulder portion 220 and coupled with a fastener 224 extending into the shoulder portion 220. The rotors 132A, 132B may be directly coupled to the rotor hub 222 via the rotor fasteners 184 described above. In addition to the shoulder portion 220, the motor shaft 134 may define a hole 226 that extends the length of the motor shaft 134 along the motor axis A1. The rotors 132A, 132B, the rotor hub 222, and the motor shaft 134 are thermally coupled so as to conduct thermal energy therebetween. Specifically, any heat from the rotors 132A, 132B will be transferred to the rotor hub 222 and the motor shaft 134. As will be discussed in further detail below, heat may be transferred away from the motor shaft 134 via the hole 226.

[0035] Continue to refer Fig. 7A-8, the stator 130 has a first side 170 and a second side 172. The stator 130 can be arranged so that the first side 170 is oriented away from the longitudinal axis A3 of the vehicle 30 and the second side 172 is oriented toward the longitudinal axis A3. Here, the first side 170 can be toward the outside and the second side 172 can be toward the inside. The stator 130 includes a stator body 174, which has a generally annular shape with an outer edge 176 and an inner edge 178. The stator body 174 is coupled to the housing 104 via a series of holes 180 defined in the stator body 174 near the outer edge 176. Each hole 180 is configured to receive a fastener 182, which can engage with the first body 148 and / or the second body 150 to secure the stator body 174 to the housing 104. The stator body 174 may further define a return passage 244 extending through the stator body 174 between the first side 170 and the second side 172 , as will be discussed in greater detail below.

[0036] The stator 130 also includes a plurality of coils 188, each coupled to the stator body 174 and arranged radially around the motor axis A1. Each coil 188 may be wound to form a generally trapezoidal ring defining a magnetic flux vector. The coils 188 are coupled to the stator body 174, wherein the magnetic flux vector is oriented parallel to the motor axis A1. When electricity passes through each coil 188, a magnetic field is generated that interacts with the magnets 186 coupled to the rotors 132A, 132B, causing the motor shaft 134 to rotate. When current flows through the coils 188, heat is generated, which may affect the performance of the motor 106.

[0037] like Fig. 7A As shown in Figure 8, according to a first configuration of the drive assembly 100, the stator 130 defines a stator conduit 190 having a conduit inlet 192 and a conduit outlet 194. The stator conduit 190 is a cavity within the stator body 174 that is configured to distribute the first heat transfer fluid throughout the stator body 174 in response to a pressure difference between the conduit inlet 192 and the conduit outlet 194. Each coil 188 is at least partially disposed in the stator conduit 190 in contact with the first heat transfer fluid flow. The stator conduit 190 distributes the first heat transfer fluid flow to each coil 188 coupled to the stator body 174. The contact between the coils 188 and the first heat transfer fluid allows the coils 188 to exchange thermal energy between them, and the first heat transfer fluid flow increases the rate at which thermal energy can be removed.

[0038] Because the first heat transfer fluid is in contact with the coils 188 of the motor 106, electrical conductivity is an important consideration. Due to the relatively large amount of energy required to move the fully loaded vehicle 30 and thus operate the drive assembly 100, the voltage and / or current in the coils 188 are also relatively high. In addition, the efficient operation of the synchronous motor benefits from the precise control of the electrical signal supplied to the coils 188. The electrical insulation of the coils 188 reduces the possibility of short circuits and other potential undesirable effects. In the first construction, one type of the first heat transfer fluid is a dielectric oil (insulating oil), which is non-conductive and therefore prevents current from flowing between the coils 188. For example, the first heat transfer fluid can be a mineral oil or a silicone oil. In some embodiments (discussed below), the first heat transfer fluid can have a lubricating additive for reducing friction between the components of the gear arrangement 108. Alternatively, in the second construction to be described, the first heat transfer fluid can be a water / ethylene glycol mixture. Alternative fluids are contemplated.

[0039] Now turn to Figure 5 and 6 , according to the first configuration of the drive assembly 100, the cooling conduit 196 is further shown in detail together with the details of the stator cooling circuit 228. The stator cooling circuit 228 can be defined by the cooperation of the cooling conduit 196, the stator pipe 190 and the pump 230 to circulate the first heat transfer fluid. Generally, the stator cooling circuit 228 is substantially disposed within the interior 146 of the housing 104. More specifically, the cooling conduit 196, the stator pipe 190 and the pump 230 are each arranged in the interior 146 so that the first heat transfer fluid does not circulate outside the housing 104. The drive assembly 100 can be configured so that the stator cooling circuit 228 is fluidly separated from the gear chamber 152 and the heat chamber 154, and portions of the stator cooling circuit 228 are disposed in both the gear chamber 152 and the heat chamber 154. The first heat transfer fluid can be sealed within the housing 104 and is not mixed or contaminated by other fluids that can be used with the drive assembly 100. The drive assembly 100 may also be configured such that the stator cooling circuit 228 is fluidly separated from the heat chamber 154 but in fluid communication with the gear chamber 152 .

[0040] exist Fig. 9-11, a second configuration of the drive assembly 100' is shown. In many respects, the drive assembly 100' can be similar to the first configuration of the drive assembly 100 described herein, with the same reference numerals corresponding to the same components (plus a prime, such as 100'). Here, the stator cooling circuit 228' can be defined by the cooperation of the heat chamber 154' and the stator duct 190'. Generally, the stator cooling circuit 228' is fluidly coupled to a heat exchanger, which can be part of the vehicle cooling system of the electric vehicle 30. More specifically, the heat chamber 154' is fluidly coupled to the stator duct 190', which are fluidly coupled to transfer thermal energy therebetween. The stator cooling circuit 228' is fluidly separated from the gear chamber 152' so that a first heat transfer fluid, here a water / ethylene glycol mixture, flows between the heat chamber 154' and the stator duct 190'. In this second configuration, the cooling conduit 196' contains a lubricant that is circulated via a lubricant pump (described below) between the gear chamber 152' to cool the lubricant.

[0041] Referring again to the first configuration of the drive assembly 100 and the stator cooling circuit 228, further details of the first configuration of the heat chamber 154 are described in Figure 4 As described above, the cooling conduit 196 is disposed in the heat chamber 154 for exchanging thermal energy therebetween. Thermal energy is exchanged with the cooling conduit 196 by means of a second heat transfer fluid contained in the heat chamber 154 and in contact with the cooling conduit 196. The heat chamber 154 includes a heat chamber inlet 202 and a heat chamber outlet 204 that cooperate to define a flow path for the second heat transfer fluid. The heat chamber inlet 202 and the heat chamber outlet 204 are defined in the housing 106 and are configured to be in fluid communication with a heat exchanger (not shown) of the vehicle 30.

[0042] The flow path of the second heat transfer fluid is affected by a guide wall 206 disposed in the heat chamber 154 and protruding from the first body 148. The guide wall 206 has two curved sections that cooperate to define a convoluted path between the heat chamber inlet 202 and the heat chamber outlet 204. When the second heat transfer fluid flows from the heat chamber inlet 202 to the heat chamber outlet 204, the flow path follows the convoluted path defined by the guide wall 206. The curved sections increase the surface area of ​​the guide wall 206 that contacts the second heat transfer fluid. In addition, the shape of the convoluted path increases the length of the flow path between the heat chamber inlet 202 and the heat chamber outlet 204. By increasing the surface area of ​​the guide wall 206 and the length of the flow path, conduction between the second heat transfer fluid and the housing 104 is increased.

[0043] The flow of the second heat transfer fluid through the heat chamber inlet 202 and into the heat chamber 154 is promoted via an inlet fitting (not shown), which is coupled to the housing 104 and configured to be coupled to a cooling system circulating in the vehicle 30. Similarly, the flow of the second heat transfer fluid through the heat chamber outlet 204 and out of the heat chamber 154 is promoted via an outlet fitting (not shown), which is coupled to the housing 104 and configured to be coupled to a cooling system. The inlet fitting and the outlet fitting may include a threaded portion that seals the fitting to the housing 104, or a gasket flange that is fastened to the housing 104 may be used. Similarly, the inlet and outlet fittings may include hose barbs or other fluid couplings to interface with the cooling system in the vehicle. One type of fluid for the second heat transfer fluid is a water-based coolant, which may be treated to inhibit corrosion and reduce freezing point. For example, glycol-type antifreeze / coolant common in automotive applications may be used.

[0044] like Figure 3 and 4 , an exemplary arrangement of the heat chamber 154 is shown, wherein the heat chamber inlet 202 may be positioned in a portion of the swirling path of the heat chamber 154 corresponding to the conduit outlet 200. In this exemplary configuration of the heat chamber 154, the heat chamber outlet 204 may be positioned in a portion of the swirling path of the heat chamber 154 corresponding to the conduit inlet 198. Thus, the flow path of the second heat transfer fluid is arranged in a counter-flow configuration relative to the flow path of the first heat transfer fluid through the cooling conduit 196. In the counter-flow configuration, the first heat transfer fluid flows through the cooling conduit 106 in a direction opposite to the flow of the second heat transfer fluid through the heat chamber 154. The heat chamber 154 may also be arranged in a parallel flow configuration, wherein the heat chamber inlet 202 may be positioned in a portion of the swirling path of the heat chamber 154 corresponding to the conduit inlet 198, and the heat chamber outlet 204 may be positioned in a portion of the swirling path of the heat chamber 154 corresponding to the conduit outlet 200. In the parallel flow configuration, the first heat transfer fluid flows through the cooling conduits 106 in the same direction as the second heat transfer fluid flows through the heat chamber 154 .

[0045] To prevent cross contamination of the second heat transfer fluid with the lubricant, fluid communication between the heat chamber 154 and the gear chamber 152 is prevented. To prevent fluid communication, the drive assembly 100 also includes an interface plate 208 coupled to the first body 148 between the gear chamber 152 and the heat chamber 154. The interface plate 208 has a generally annular body 210 and a circular outer flange 212 extending between the annular body 210 and a lip 214. The interface plate 208 may define a hole 216 that allows the cooling conduit 196 to enter the heat chamber 154.

[0046] The interface plate 208 is disposed within the interior 146 of the housing 104, wherein the annular body 210 engages the guide wall 206. The outer flange 212 engages the first body 148 to enclose the heat chamber 154. The lip 214 is clamped between the stator 130 and the first body 148 to secure the interface plate 208. The interface plate 208 may be manufactured from a sheet material that is stamped to form the outer flange 212 and the lip 214. Here, the engagement of the outer flange 212 and the first body 148 is sufficient to contain the second heat transfer fluid within the heat chamber 154, but a gasket and / or sealant (not shown) may also be used to further seal the heat chamber 154.

[0047] like Fig. 7A As shown, one side of the interface plate 208 is in direct contact with the second heat transfer fluid in the heat chamber 154. The opposite side of the interface plate 208 is in direct contact with the gear chamber 152. During operation of the drive assembly 100, the cooling flow of the second heat transfer fluid entering the heat chamber 154 removes heat from the heat chamber facing side of the interface plate 208, which reduces the temperature of the gear chamber facing side of the interface plate 208, thereby allowing the annular body 210 to act as a cold wall. The annular body 210, which has a diameter similar to that of the heat chamber 154 and the motor 106, can advantageously cool the gear chamber 152 and the motor 106 due to its close proximity to the rotor 132A. Removing excess thermal energy from the rotor 132A allows efficient operation of the motor 106 and prevents overheating of the magnets 186 coupled to the rotor 132A.

[0048] On the opposite side of the motor 106, the drive assembly 100 may also include a rotor shroud 270 disposed in the gear chamber 152. The rotor shroud 270 is adjacent to the inward rotor 132B and is axially spaced toward the inward side 164 of the housing 104. Because the rotors 132A, 132B rotate relatively fast compared to the other components of the gear arrangement 108, the drag losses from the lubricant may be the greatest. The rotor shroud 270 prevents excess lubricant dispersed within the gear chamber 152 from accumulating on the inward rotor 132B. In addition, in order to maximize the efficiency of the motor 106, the distance between the rotors 132A, 132B and the stator 130 is relatively small. By preventing the dispersed lubricant from entering between the rotors 132A, 132B and the stator 130, the losses caused by viscous effects are greatly reduced.

[0049] To achieve the flow of the first heat transfer fluid, the pump 230 is fluidly coupled between the cooling conduit 196 and the stator duct 190. The pump 230 includes a motor and a pumping element (not shown) that can be disposed inside a pump housing 232. The pump 230 also includes a pump inlet 234 and a pump outlet 236 that are fluidly connected to the pumping element and disposed on the pump housing 232. When power is supplied to the motor to drive the pumping element, the pump operates, thereby generating a pressure difference between the pump inlet 234 and the pump outlet 236. The pump 230 may include an alternative component in addition to or in place of the motor and / or the pumping element, which is operable to achieve a pressure difference between the pump inlet 234 and the pump outlet 236. In an exemplary embodiment of the pump 230, the pumping element may be a cycloid positive displacement pump that is operably coupled to the motor 106 to rotate the rotor. Alternatively, the pumping element may be implemented as an axial piston pump that is driven by an electric motor in the pump housing 232. Other pumping elements are also contemplated.

[0050] like Figure 6 As shown, a pump inlet 234 and a pump outlet 236 can be defined by the pump housing 232 for receiving a suction line 238 and a pressure line 240, respectively. The suction line 238 is fluidly coupled to the pump inlet 234 to direct the first heat transfer fluid into the pumping element, and the pressure line 240 is fluidly coupled to the pump outlet 236 to direct the first heat transfer fluid out of the pumping element. In addition, the pump housing 232 may include a pump flange 242, which may define a hole for receiving a fastener to couple the pump 230 to the housing 104. When coupled to the housing 104, the pump 230 may be partially or completely disposed within the interior 146. Fig. 7A 1 , pump 230 is shown having a pump housing 232 disposed substantially within interior 146 having a pump inlet 234 and a pump outlet 236 disposed in gear chamber 152 , and a pump flange 242 coupled externally to housing 104 .

[0051] As described above, the cooling conduit 196, the stator duct 190, and the pump 230 cooperate to define a first configuration of the stator cooling circuit 228. To this end, the cooling conduit 196 is in fluid communication with the stator duct 190 and the pump 230 so that the first heat transfer fluid can flow therebetween. Specifically, as part of the stator cooling circuit 228, the cooling conduit 196 allows thermal energy generated in the stator 130 and transferred to the first heat transfer fluid to be further transferred to the heat chamber 154 and the second heat transfer fluid. More specifically, the cooling conduit 196 has a conduit inlet 198 and a conduit outlet 200, whereby the conduit inlet 198 is fluidly coupled to the conduit outlet 194 of the stator duct 190, and the conduit outlet 200 is fluidly coupled to the pump 230. In some cases, such as here, the cooling conduit 196 may include a suction line 238, which is fluidly coupled to the pump inlet 234.

[0052] The cooling conduit 196 is composed of a tubular material that has been bent or otherwise formed into a desired shape. An exemplary material that can be used to construct the cooling conduit 196 is an aluminum tube, which can be drawn, extruded, welded or otherwise manufactured using known methods. Other materials such as copper, as well as material enhancement processes such as anodizing and / or alternative coatings are also envisioned. The cooling conduit 196 can be assembled from one or more sections, which are connected during manufacturing to form a continuous path between the conduit inlet 198 and the conduit outlet 200. In addition, these sections can be connected in series, wherein the first heat transfer fluid flows sequentially through each section as a whole, or can be connected in parallel, wherein the first heat transfer fluid flow is divided between multiple sections. The cooling conduit 196 may include a plurality of nested sections 246, including an innermost section 248 and an outermost section 250 connected in series. The cooling conduit 196 may also include a plurality of axially stacked sections 252 connected in parallel with a manifold 254. The various segments of the cooling conduit 196 may be coupled together via welding, soldering, brazing, swaging, gluing, and other joining processes appropriate to the particular material of the cooling conduit 196. Alternatively, couplings or clamps (not shown) may be used to couple each segment.

[0053] Due to the arrangement of the heat chamber 154 within the housing 104, the stator cooling circuit 228 turns around the outer rotor 132A when routed from the stator duct 190 to the heat chamber 154 and passes through the hole 216 in the interface plate 208. The stator cooling circuit 228 follows a convoluted path defined by the guide wall 206 in the heat chamber 206. More specifically, the cooling conduit 196 defines an axially centered convoluted shape. The axially centered convoluted shape of the cooling conduit 196 is generally aligned with the motor axis A1. The conduit inlet 198 is radially spaced from the motor axis A1 to receive a flow of the first heat transfer fluid that has turned around the outer rotor 132A and entered the heat chamber 154.

[0054] The aforementioned plurality of nested segments 246 are arranged to form an axially centered spiral shape of the cooling conduit 196. The plurality of nested segments 246 are further arranged in the heat chamber 154 to follow a spiral path defined by the guide wall 206. The innermost segment 248 is positioned closer to the motor axis A1, while the outermost segment 250 is positioned further away from the motor axis A1. The innermost segment 248 is coupled to the conduit inlet 198 so that when the first heat transfer fluid enters the conduit inlet 248, the flow is directed generally toward the motor axis A1. As the first heat transfer fluid continues to flow through the cooling conduit 196, the flow travels through the nested segments 246 in a semicircular path with alternating radii. The outermost segment 250 is coupled to the conduit outlet 200 so that the first heat transfer fluid exiting the conduit outlet 250 is directed away from the motor axis A1 and exits the heat chamber 154 around the outer rotor 132A.

[0055] Reference is again made to the plurality of axially stacked segments 252 of the cooling conduit 196. In contrast to the nested segments 246 arranged in an axially centered spiral shape aligned with the motor axis A1, the axially stacked segments 252 are spaced apart along the motor axis A1. The axially stacked segments 252 are fluidly coupled in parallel via a manifold 254 that divides the flow of the first heat transfer fluid between each of the axially stacked segments 252. Fig. 7A and 7B As shown, the cooling conduit 196 includes three axial sections 252, each axial section 252 being formed by a plurality of nested sections 246. The nested sections 246 forming each axial section 252 are coupled in series, and each set of series-coupled nested sections 246 are coupled in parallel. The increased surface area provided by the plurality of axially stacked sections 252 provides increased heat transfer between the first heat transfer fluid and the second heat transfer fluid.

[0056] Reference now Figure 8 and the routing of the stator cooling circuit 228 between the hot chamber 154 and the pump 230. As described above, the duct inlet 198 is fluidly coupled to the duct outlet 194, which is disposed on the first side 170 of the stator 130. In order to route the duct outlet 200 to the pump inlet 234, the duct outlet 200 and the suction line 238 are disposed in a return channel 244 defined in the stator 130. The return channel 244 reduces the space required to route the duct outlet 200 and the suction line 238 around the stator 130 and the inner rotor 132B.

[0057] The first heat transfer fluid that has been discharged by the pump 230 exits the pump outlet 236 into a pressure line 240 that is fluidly coupled to both the pump outlet 236 and the conduit inlet 192. The pressure line 240 is disposed in the gear chamber 152 and extends between the pump outlet 236 and the conduit inlet 192 to direct the first heat transfer fluid around the inward rotor 132B. The pressure line 240 may be implemented as a solid tubular material formed in a substantially similar process to the cooling conduit 196, or as a flexible hose that facilitates increased maintainability of the pump 230 and / or the stator cooling circuit 228.

[0058] In addition to the stator cooling circuit 196 discussed herein, the drive assembly 100 may also include a lubrication system for providing a pressurized supply of lubricant to the contact surfaces of the various gears and bearings throughout the gear arrangement 108. To this end, the lubrication system may include a lubricant pump 256, which may be coupled to the housing 104 with a pick-up tube and a lubricant adapter (not shown). The pick-up tube is positioned in the sump 156 to collect lubricant that has been discharged from the gear chamber 152. The lubricant pump 256 discharges the lubricant from the sump 156 through a suction tube and into a lubricant passage defined in the housing 104. Fig. 7A146. A first lubricant passage 258 is shown in the drawings to supply oil to the motor bearings 218A, 218B. Similar to the pump 230 described above for the first heat transfer fluid, the lubricant pump 256 may include a lubricant pump housing 266, which may have a lubricant pump flange 268 to couple the lubricant pump 256 to the housing 104. When coupled to the housing 104, the lubricant pump 256 may be partially or completely disposed within the interior 146.

[0059] As described above, certain configurations of the drive assembly 100 may utilize a stator cooling circuit 228 in fluid communication with the gear chamber 152. To this end, the stator cooling circuit 228 and the lubrication system may be integrated so that the first heat transfer fluid also serves as a lubricant. Here, only one pump will be used to achieve the flow of the lubricating heat transfer fluid into the stator 130 and the cooling conduit 196 and into the lubricant passage 258.

[0060] A first lubricant passage 258 is defined in the second body 150 and extends between the lubricant adapter and a passage tap 260 adjacent to the second motor bearing 218B. Lubricant discharged from the lubricant pump 256 flows through the lubricant adapter and enters the first lubricant passage 258 to the passage tap 260. Because the lubricant tap 260 is arranged adjacent to the second motor bearing 218B, part of the lubricant flows between the inner race and the outer race of the second motor bearing 218B, and part of the lubricant flows into the hole 226 of the motor shaft 134. Heat from the rotors 132A, 132B that has been transferred to the motor shaft 134 can be absorbed by the lubricant flowing through the hole 226. The lubricant that has been pumped through the second motor bearing 218B and the hole 226 exits through the first motor bearing 218A, further lubricating and reducing the heat of the contact surface. During operation of the motor 106, the lubricant flows through the first motor bearing 218A into the gap 262 between the interface plate 208 and the outward rotor 132A.

[0061] refer to Fig. 7A and 7B , the lubricant entering the gap 262 will contact the interface plate 208 and the outward rotor 132A. During operation of the motor 106, the rotors 132A, 132B rotate about the motor axis A1 relative to the interface plate 208. The lubricant in contact with the rotating outward rotor 132A is carried and accelerated away from the motor axis A1 around the motor axis A1 until it reaches the edge of the outward rotor 132A and is dispersed into the gear chamber 152. The dispersed lubricant settles and collects on the windage wall 166. However, when the lubricant contacts the outward rotor 132A, the heat energy generated in the outward rotor 132A during operation is absorbed. In addition, the lubricant forms a conductive interface between the outward rotor 132A and the interface plate 208 for transferring heat energy to the heat chamber 154.

[0062] In order to return the lubricant collected on the windage wall 166 to the sump 156, where it can be cooled and degassed, a drain hole 264 is defined in the windage wall 166. The windage wall 166 is positioned in the gear chamber 152 below the gap 262 between the outward rotor 132A and the interface plate 208. Lubricant that drains from the gap 262 and onto the windage wall 166 is directed toward the drain hole 264. The flow of lubricant across the windage wall 166 further transfers heat into the housing 104, and thus into the heat chamber 154, and degases the lubricant.

[0063] As mentioned above and Fig. 9 -11, in the second configuration of the stator cooling circuit 228', the heat chamber 154' and the stator duct 190' cooperate to transfer thermal energy therebetween. Specifically, as a part of the stator cooling circuit 228', the heat chamber 154' allows the thermal energy generated in the stator 130' and transferred to the first heat transfer fluid to be further transferred out of the drive assembly. More specifically, the first heat transfer fluid from the vehicle cooling system is received in the housing port 274', which extends through the housing 104' into the duct inlet 192'. The duct inlet 192' is arranged on the outer edge 176' of the stator body 174' and allows the first heat transfer fluid to flow from the housing port 274' into the stator duct 190'. The first heat transfer fluid in the stator duct 190' absorbs thermal energy from the coil 188 and then flows out of the duct outlet 194'.

[0064] Here, the heat chamber inlet 202' is fluidly coupled to the duct outlet 194' to receive a flow of the first heat transfer fluid heated by the coil 188'. To route the first heat transfer fluid around the rotor 132A', the duct outlet 194' is defined in the first side 170' of the stator body 174', proximate the outer edge 176' between the fasteners 182' that secure the stator 130' to the housing 104'. The heat chamber inlet 202' is defined in the outer flange 212' of the interface plate 208', which seals against the duct outlet 194'. The first heat transfer fluid entering the heat chamber 154' follows a circling path around the motor axis A1, cooling the lubricant contained in the cooling conduit 196' toward the heat chamber outlet 204'. The first heat transfer fluid in the heat chamber 154' absorbs thermal energy from the cooling conduit 196', the housing 104', and the rotor 132A' and then flows out of the heat chamber outlet 204'. Flow of the first heat transfer fluid out of the heat chamber 154' may be facilitated via an outlet fitting (not shown) coupled to the housing 104' and configured to couple to a cooling system.

[0065] As used herein, spatial relative terms are used to describe the relationship of one element to another element for ease of description, which is not intended to be restrictive. On the contrary, these terms are only used to distinguish one element from another element. It has been described relative to the flow direction of the fluid contained in certain elements (i.e., entering at the inlet and leaving at the outlet). It should be understood that the negative pressure gradient will cause the fluid to flow in the opposite direction (i.e., entering at the outlet and leaving at the inlet), and therefore the terms used to describe these elements are only for the purpose of explanation. For example, the terms "inlet" and "outlet" are only used to explain the interconnection of elements, rather than to limit the direction of fluid flow. More specifically, although the second configuration of the stator cooling circuit 228' has been described so that the first heat transfer fluid is received in the shell port 274 and the pipe inlet 192' and leaves at the hot chamber outlet 204', the first heat transfer fluid can be alternatively received by the hot chamber outlet 204' and leave at the pipe inlet 192' and the shell port 274'.

[0066] Several examples have been discussed in the foregoing description. However, the examples discussed herein are not intended to be exhaustive or to limit the invention to any particular form. The terms used are intended to be descriptive rather than restrictive. In view of the above teachings, many modifications and variations are possible, and the invention may be practiced in ways other than those specifically described.

Claims

1. A drive assembly for an electric vehicle, the drive assembly comprising: an electric machine having a motor shaft defining a motor axis and including a rotor coupled to the motor shaft, and also including a stator disposed about the motor axis, wherein the stator defines a stator duct having a duct inlet and a duct outlet; a cooling conduit having a conduit inlet and a conduit outlet, wherein the cooling conduit contains a first heat transfer fluid; a gear arrangement operatively engaged with the electric motor for transmitting rotation of the motor shaft to one or more wheels of the electric vehicle; a housing defining a gear chamber and a heat chamber fluidly separated from the gear chamber, wherein the heat chamber has a heat chamber inlet and a heat chamber outlet and contains a second heat transfer fluid; wherein the motor is coupled to the housing such that the rotor is arranged adjacent to the heat chamber and the gear arrangement is disposed in the gear chamber; wherein one of the cooling conduit and the heat chamber is fluidly coupled to the stator duct to transfer thermal energy therebetween; and Wherein, the cooling conduit is at least partially disposed in the heat chamber for transferring heat energy between the first heat transfer fluid and the second heat transfer fluid.

2. The drive assembly according to claim 1, characterized in that: The conduit inlet is fluidly coupled to the duct outlet of the stator duct.

3. The drive assembly according to claim 2, characterized in that: Also included is a pump fluidly coupled to the conduit outlet and the duct inlet, wherein the stator duct, the pump, and the cooling duct cooperate to define a stator cooling circuit.

4. The drive assembly according to claim 3, characterized in that: The stator cooling circuit is fluidly separated from the gear chamber.

5. The drive assembly according to any one of claims 1 to 4, characterized in that: The other of the cooling conduit and the heat chamber is configured to be fluidly coupled to a heat exchanger on the electric vehicle.

6. The drive assembly according to any one of claims 1 to 4, characterized in that: The other of the cooling conduit and the heat chamber is in fluid communication with the gear chamber.

7. The drive assembly according to any one of claims 1 to 4, characterized in that: Also included is a pump fluidly coupled to the conduit inlet.

8. The drive assembly according to claim 7, characterized in that: The conduit inlet is fluidly coupled to the hot cell outlet.

9. The drive assembly according to claim 7, characterized in that: The conduit outlet is fluidly coupled to the hot cell inlet.

10. The drive assembly according to any one of claims 1 to 4, characterized in that: The electric machine also includes a plurality of coils coupled to the stator and at least partially disposed in the stator conduit for contacting the first heat transfer fluid.

11. The drive assembly of any one of claims 1-4, further comprising an interface plate coupled to the housing between the gear chamber and the thermal chamber, and wherein the interface plate is configured to prevent fluid communication between the gear chamber and the thermal chamber.

12. The drive assembly according to claim 11, characterized in that A guide wall is disposed in the heat chamber and extends between the interface plate and the housing to define a swirling path for the second heat transfer fluid.

13. The drive assembly according to any one of claims 1 to 4, characterized in that: The housing includes a first body and a second body coupled to the first body and at least partially defining the gear chamber.

14. The drive assembly according to claim 13, characterized in that Also included is a brake component coupled to the first body for decelerating the electric vehicle, wherein the heat chamber is disposed in the first body for absorbing heat from the brake component.

15. The drive assembly according to claim 3, characterized in that The cooling conduit defines an axially centered convoluted shape such that the first heat transfer fluid follows the axially centered convoluted shape between the conduit outlet and the pump inlet.

16. The drive assembly according to any one of claims 1 to 4, characterized in that: The cooling duct includes a plurality of nested sections coupled in series, and wherein the duct inlet is coupled to an innermost section and the duct outlet is coupled to an outermost section.

17. The drive assembly according to claim 16, characterized in that The plurality of nested segments define an axially-centered convoluted shape such that the first heat transfer fluid flowing from the conduit inlet to the conduit outlet follows the axially-centered convoluted shape.

18. The drive assembly according to claim 17, characterized in that The plurality of nested segments are arranged in the heat chamber such that a center of convolution of the axially-centered convoluted shape is aligned with the motor axis.

19. The drive assembly according to any one of claims 1 to 4, characterized in that: A gap is defined between the rotor and the heat chamber, and wherein the gap opens to the gear chamber to allow lubricant disposed in the gear chamber to enter.

20. The drive assembly according to claim 19, characterized in that The motor shaft defines a bore in fluid communication with the gap such that lubricant flowing through the bore is directed into the gap to cool the lubricant.

21. The drive assembly according to any one of claims 1 to 4, characterized in that: The cooling duct includes a plurality of axially stacked sections coupled in parallel and arranged along the motor axis.

22. The drive assembly according to any one of claims 1 to 4, characterized in that: The first heat transfer fluid is sealed within the housing.

23. The drive assembly according to any one of claims 1 to 4, characterized in that: The electric machine further comprises an output pinion coupled to the motor shaft and disposed in the gear housing connected to the gear arrangement.

24. The drive assembly according to any one of claims 1 to 4, characterized in that: The motor is configured such that the rotor is axially spaced apart from the stator.

25. The drive assembly according to claim 24, characterized in that The stator has a first side and a second side, and wherein the rotor is disposed between the first side of the stator and the cooling duct.

26. The drive assembly according to claim 25, characterized in that The rotor is further defined as an inward rotor and an outward rotor, and wherein the outward rotor is disposed on the first side of the stator and the inward rotor is disposed on the second side of the stator.

27. The drive assembly according to claim 25, characterized in that The stator further defines a return passage extending between the first side and the second side, and wherein the conduit outlet is disposed in the return passage.

28. The drive assembly according to any one of claims 1 to 4, characterized in that: The heat chamber is arranged in the housing adjacent to the gear chamber.

29. The drive assembly according to any one of claims 1 to 4, characterized in that: The first heat transfer fluid is further defined as a dielectric oil.

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