In-wheel motor system

Abstract

An in-wheel motor system is disclosed. The in-wheel motor system may comprise: a wheel hub including a hub disk portion defining one surface thereof and a hub cylindrical portion extending from the outer diameter end of the hub disk portion in the wheel axis direction, the other surface opposite to the one surface being opened; a wheel hub cover coupled to the other surface of the wheel hub and including a driven gear provided on an outer diameter portion thereof; and a driving motor assembly disposed in the wheel hub and configured to provide driving power.

Description

In-wheel motor system

[0001] The present invention relates to a wheel drive system, and more particularly, to an in-wheel motor system suitable for a future mobility platform that can improve vehicle loadability and expand the interior space of a vehicle by providing a drive motor, a reduction gear, a brake device, and a cooling system within the space of a wheel hub.

[0002] Due to recent strengthened environmental and fuel efficiency regulations, the use of eco-friendly vehicles such as hybrid and electric vehicles is increasing. Eco-friendly vehicles incorporate electric motors as their power source, and various types of eco-friendly vehicle drive systems can be implemented depending on the arrangement of the electric motor and reducer.

[0003] One of the various powertrain layouts for eco-friendly vehicles is the wheel drive system, which places the powertrain within or near the wheel hub. Conventional wheel drive systems are bulky, with portions protruding beyond the wheel hub. This can interfere with vehicle components such as suspension and braking systems. Consequently, installing conventional wheel drive systems necessitates changes to the body or chassis design.

[0004] To address these issues, the in-wheel motor system was developed. This system places the electric motor and reduction gear within the wheel hub.

[0005] In conventional in-wheel motor systems, oil for cooling the drive motor and operating oil for the brake system were supplied by an oil cooling system and brake control system installed in the body or chassis. Additionally, the parking brake for parking was mounted outside the wheel.

[0006] Therefore, hydraulic hoses to supply the hydraulic pressure generated from the oil cooling system and brake control system outside the wheel to the wheel's drive motor and brake device, as well as wires for operating the parking brake, had to be provided at the point connecting the wheel to the body or chassis. In other words, when installing an in-wheel motor, hydraulic hoses and wires had to be all placed at the connection point between the in-wheel motor system and the body, making vehicle installation difficult. Furthermore, the application of by-wire technology, which is controlled solely by electricity, was limited due to the hydraulic hoses, etc.

[0007] The information contained in this background section is intended to enhance understanding of the background of the invention and may include matters that are not prior art and are already known to those of ordinary skill in the art.

[0008] An embodiment of the present invention provides a compact in-wheel motor system that includes a drive motor, a reduction gear, a brake, a parking brake, and a cooling system all within the space of a wheel hub, thereby improving vehicle loadability and expanding interior space, and providing an in-wheel motor system to which by-wire technology can be applied.

[0009] An in-wheel motor system according to an embodiment of the present invention comprises: a wheel hub including a hub disk portion defining one side, a hub cylindrical portion extending in the direction of a wheel axis from an outer diameter end of the hub disk portion, and an opposite side, which is an open side; a wheel hub cover coupled to the opposite side of the wheel hub and including a driven gear provided on the outer diameter portion; And a drive motor assembly disposed within the wheel hub and configured to provide driving force, the drive motor assembly comprising a cylindrical motor housing, a stator fixed within the motor housing and generating a magnetic field, a rotor rotatably disposed radially inward of the stator with a gap set from the stator, a rotor shaft coupled to the rotor and rotating together with the rotor and extending in the axial direction, a brake shaft including a rear end operatively coupled to a front end of the rotor shaft and a front end provided with a drive gear meshed with the driven gear, a brake housing mounted on the brake shaft and including a front and side surfaces, a friction disc pack disposed within the brake housing and selectively connecting the brake housing and the brake shaft, a brake including a piston forming a piston chamber between the front of the brake housing and the front end of the friction disc pack and compressing and coupling the friction disc pack toward the drive motor, and a booster lever disposed at the rear end of the friction disc pack and configured to compress the friction disc pack toward the piston, and an actuator configured to apply a force for compressing the friction disc pack to the booster lever. It may include a parking brake.

[0010] The rotor shaft is configured as a hollow shaft, and the rear end of the brake shaft can be inserted into the front end of the rotor shaft and spline-joined.

[0011] The above motor housing includes an open front, a side, and an open rear, and a front motor cover is coupled to the open front, a rear motor cover is coupled to the open rear, a brake housing is coupled to the front of the front motor cover, and the rotor shaft and the brake shaft can be spline-coupled to each other while penetrating the front motor cover.

[0012] A hub hole is formed in the center of the hub disc portion, a hub cover hole is formed in the center of the wheel hub cover, and the motor housing further includes an outer arm that protrudes from one side toward the wheel axis and is inserted into the hub hole of the hub disc portion, and an inner arm that protrudes from the other side toward the wheel axis and penetrates the hub cover hole, and a bearing can be arranged between the outer arm and the inner surface of the hub disc portion and between the inner arm and the inner surface of the wheel hub cover, respectively.

[0013] The brake further comprises a disc hub operatively coupled to the brake shaft so as to rotate with the brake shaft, wherein a portion of the friction disc pack is spline-coupled to the disc hub and another portion is spline-coupled to the brake housing such that the portion of the friction disc pack and the other portion are frictionally coupled to each other by a force acting axially of the brake shaft.

[0014] The piston presses the friction disc pack against the front motor cover by the operating pressure supplied to the piston chamber to frictionally engage the friction disc pack, and the power lever receives force from the actuator to press the friction disc pack against the front of the brake housing to frictionally engage the friction disc pack.

[0015] The above parking brake further includes a plunger link hinge-connected to the actuator and the power lever to transmit the force of the actuator to the power lever, one side of the power lever being hinge-connected to the front motor cover, and the other side of the power lever protruding outward from the brake housing, to which the plunger link can be connected.

[0016] A convex-shaped boost lever shoe may be provided on the rear side of the friction disc pack, and a concave-shaped boost lever shoe groove may be provided at a position of the boost lever corresponding to the boost lever shoe.

[0017] The inside of the wheel hub and the wheel hub cover, which are coupled to each other, are filled with oil, and the in-wheel motor system may further include a funnel having one side opened to receive oil by oil churning when the wheel hub and the wheel hub cover, which are coupled to each other, are mounted on the rear side of the rear motor cover.

[0018] The above in-wheel motor system may further include a hydraulic control module configured to generate operating pressure and supply it to the brake or to generate cooling flow for cooling and supply it to the drive motor and brake.

[0019] The hydraulic control module may further include an oil pump configured to suck oil within the wheel hub to generate operating pressure or cooling flow rate; a control block provided with first and second outlets; and at least one solenoid valve configured to select at least one of the first and second outlets and to regulate the pressure and flow rate of oil discharged through the selected outlet.

[0020] The first outlet can supply oil to the piston chamber through a connecting pipe connected to the first outlet and a brake operating oil passage formed in the brake housing.

[0021] The second outlet can supply cooling fluid into the motor housing and the rotor shaft through a cooling oil supply passage formed in the motor housing and a rear motor cover oil passage formed in the rear motor cover.

[0022] An oil distributor may be provided inside the motor housing corresponding to the rear motor cover oil passage, and the oil distributor may be configured to send the cooling flow to the cooling channel between the motor housing and the stator and the gap between the rotor and the stator.

[0023] The cooling flow passing through the cooling channel between the motor housing and the stator and the gap between the rotor and the stator can be discharged to the outside of the motor housing through the first cooling oil outlet formed at the front part of the motor housing.

[0024] Cooling flow supplied into the rotor shaft can be supplied to the friction disc pack through the interior of the brake shaft and the disc hub.

[0025] The cooling fluid passing through the friction disc pack can be discharged to the outside of the brake housing through a second cooling fluid outlet formed on the side of the brake housing.

[0026] A funnel oil passage is formed on the opposite side of one side of the above funnel, and the funnel oil passage can be communicated with the rear motor cover oil passage and the inside of the rotor shaft.

[0027] The above drive motor assembly is positioned so that the brake is close to the ground, so that the oil collected by the funnel can flow into the interior of the drive motor and the brake by its own weight, thereby cooling the drive motor and the brake.

[0028] Depending on the position of the brake and the oil level setting, the brake may be immersed in oil within the wheel hub when the vehicle is stopped or driving at low speeds, and may be exposed to air when driving.

[0029] According to the present invention, a drive motor assembly, a reduction gear set, a brake device, a parking brake device, and a cooling system are provided within the space of a wheel hub, thereby improving vehicle loadability and expanding the interior space of the vehicle.

[0030] Additionally, weight and cost can be reduced by sharing the friction disc pack between the brake and parking brake.

[0031] Additionally, the cooling system of the drive motor and brakes installed inside the wheel allows the elimination of hydraulic hoses connected to the body.

[0032] The oil that cools the drive motor and brake is discharged through the first coolant outlet and the second coolant outlet and collected in the lower space of the wheel hub. The oil collected in the lower space of the wheel hub comes into contact with the wheel hub and the wheel hub cover and rotates together, is cooled by the air flowing around the wheel, and is circulated back to the funnel and the hydraulic control module.

[0033] By adjusting the position of the above brakes and the oil level within the wheel hub, the brakes can be immersed in oil when the vehicle comes to a stop after braking, thereby rapidly transferring the heat of the brakes to the oil. In addition, when the brakes are released and the vehicle is driven, the oil level in the lower space of the wheel hub is lowered as the oil is churned by centrifugal force, thereby exposing the brakes to the air. This minimizes drag loss due to oil viscosity in the friction disc pack of the brakes during driving, thereby improving driving efficiency.

[0034] In addition, the effects that can be obtained or expected from embodiments of the present invention will be disclosed directly or implicitly in the detailed description of the embodiments of the present invention. That is, the various effects expected according to embodiments of the present invention will be disclosed in the detailed description that follows.

[0035] Embodiments of the present disclosure may be better understood by reference to the following description taken in conjunction with the accompanying drawings in which like reference numerals refer to identical or functionally similar elements.

[0036] FIG. 1 is a front perspective view of an in-wheel motor system according to an embodiment of the present invention.

[0037] FIG. 2 is a rear perspective view of an in-wheel motor system according to an embodiment of the present invention.

[0038] FIG. 3 is another rear perspective view of an in-wheel motor system according to an embodiment of the present invention without a tire.

[0039] FIG. 4 is an exploded view of an in-wheel motor system according to an embodiment of the present invention without a tire.

[0040] FIG. 5 is a front view of a drive motor assembly of an in-wheel motor system according to an embodiment of the present invention.

[0041] Figure 6 is a cross-sectional view taken along line AA of Figure 5.

[0042] Figure 7 is an exploded view of the brake and parking brake of the drive motor assembly according to an embodiment of the present invention.

[0043] Figure 8 is a perspective view of a brake and a parking brake according to an embodiment of the present invention.

[0044] Figure 9 shows the operation of a parking brake according to an embodiment of the present invention.

[0045] FIG. 10 is a perspective view of a hydraulic control module of an in-wheel motor system according to an embodiment of the present invention.

[0046] FIG. 11 is a cross-sectional view of a drive motor assembly of an in-wheel motor system according to an embodiment of the present invention, showing a brake operating oil passage.

[0047] Figure 12 shows the path through which operating oil is supplied to the piston chamber in Figure 11.

[0048] Figure 13 shows the oil path by oil churning for cooling the drive motor.

[0049] Figure 14 shows the oil path by oil churning for cooling the brakes.

[0050] Figure 15 shows the oil path by the hydraulic control module for cooling the drive motor.

[0051] Figure 16 shows the oil path by the hydraulic control module for cooling the brakes.

[0052] Figure 17 shows the oil inside the wheel hub when stopped or driving at low speed.

[0053] Figure 18 shows the oil inside the wheel hub when the vehicle is driving.

[0054] The drawings referenced above are not necessarily drawn to scale, but should be understood to present rather simplified representations of various preferred features that illustrate the basic principles of the present invention. For example, specific design features of the present invention, including specific dimensions, orientations, locations, and shapes, will be determined in part by the specific intended application and usage environment.

[0055] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly dictates otherwise. It should also be understood that the terms "comprises" and / or "comprising," as used herein, indicate the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. The term "coupled" indicates a physical relationship between two components in which the components are directly connected to one another or are indirectly connected through one or more intervening components.

[0056] The term "joining means" or similar terms means a means for joining at least two members so that they rotate together. Examples of joining means include, but are not limited to, bolts, nuts, welding, press-fitting, bonding, splines, etc.

[0057] The term "operably connected" or similar means that at least two elements are directly or indirectly connected to each other and capable of transmitting power. However, two operably connected elements do not always rotate at the same speed or in the same direction.

[0058] As used herein, the terms "vehicle" or "vehicle" or other similar terms are generally understood to include passenger cars, buses, trucks, various commercial vehicles, including sports utility vehicles (SUVs), as well as hybrid electric vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel (e.g., fuel derived from sources other than petroleum). As referenced herein, an electric vehicle (EV) is a vehicle that has, as part of its motive power, electric power derived from a rechargeable energy storage device (e.g., one or more rechargeable electrochemical cells or other type of battery). Additionally, a hybrid vehicle is a vehicle that has two or more power sources, e.g., a gasoline-based power source and an electric-based power source (e.g., a hybrid electric vehicle (HEV).

[0059]

[0060] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings.

[0061] FIG. 1 is a front perspective view of an in-wheel motor system according to an embodiment of the present invention, FIG. 2 is a rear perspective view of an in-wheel motor system according to an embodiment of the present invention, FIG. 3 is another rear perspective view of an in-wheel motor system according to an embodiment of the present invention without a tire, and FIG. 4 is an exploded view of an in-wheel motor system according to an embodiment of the present invention without a tire.

[0062] As illustrated in FIGS. 1 to 4, an in-wheel motor system (10) according to an embodiment of the present invention includes a wheel hub (20), a wheel hub cover (30), and a drive motor assembly (40). The drive motor assembly (40) is arranged in a space within the wheel hub (20) formed by the combination of the wheel hub (20) and the wheel hub cover (30) and configured to provide a driving force for rotating the wheel. A tire (12) is mounted on the outer periphery of the wheel hub (20) to increase contact with the road surface. A knuckle adapter (16) is mounted on a portion of the drive motor assembly (40) protruding from one surface of the wheel hub cover (30) through a coupling means, and a knuckle (14) is mounted on one surface of the knuckle adapter (16) through a coupling means, so that the in-wheel motor system (10) is connected to a vehicle body or a chassis through the knuckle adapter (16) and the knuckle (14).

[0063] Hereinafter, with reference to FIGS. 1 to 6, the in-wheel motor system (10) according to an embodiment of the present invention will be described in more detail.

[0064] FIG. 5 is a front view of a drive motor assembly of an in-wheel motor system according to an embodiment of the present invention, and FIG. 6 is a cross-sectional view taken along line AA of FIG. 5.

[0065] As illustrated in FIGS. 1 to 6, the wheel hub (20) forms a space for mounting the drive motor assembly (40) and is formed in a generally cylindrical shape surrounding the drive motor assembly (40). The wheel hub (20) includes a hub disc portion (22) and a hub cylindrical portion (26).

[0066] The hub disc portion (22) is formed in a generally disc shape on one side of the in-wheel motor system (10). A hub hole (23) is formed in the center of the hub disc portion (22), and a first bearing seat (24) is provided on the inner surface of the hub disc portion (22). The outer arm (44) of the drive motor assembly (40) is inserted into the hub hole (23), and the outer peripheral surface of the outer arm (44) faces the first bearing seat (24). A bearing (100) is arranged between the first bearing seat (24) and the outer peripheral surface of the outer arm (44) to assist smooth rotation of the wheel hub (20) with respect to the drive motor assembly (40).

[0067] The hub cylindrical portion (26) is formed into a cylindrical shape by extending generally in the direction of the wheel axis from the outer diameter end of the hub disc portion (22). Accordingly, a drive motor assembly (40) can be mounted within a space surrounded by the hub cylindrical portion (26). Both ends of the hub cylindrical portion (26) protrude radially outward to form a tire coupling portion (28), and the tire (12) is mounted on the tire coupling portion (28). The tire (12) may be a rubber tire, a non-pneumatic tire, a urethane wheel, or the like.

[0068] The other side of the wheel hub (20) is open, and a wheel hub cover (30) is coupled to the opened other side of the wheel hub (20). The wheel hub cover (30) is formed in a generally circular shape and has a hub cover hole (32) formed in the center. The outer end of the wheel hub cover (30) is in contact with the other end of the hub cylindrical portion (26) and is coupled using a coupling means such as a bolt. A sealing member (27) is arranged between the outer end of the wheel hub cover (30) and the other end of the hub cylindrical portion (26) to prevent oil (O) inside the wheel hub (20) from leaking out to the outside of the wheel hub (20).

[0069] A second bearing seat (34) is provided on the inner surface of the wheel hub cover (30). The second bearing seat (34) forms the hub cover hole (32), and the hub cover hole (32) is used to connect and fix the drive motor assembly (40) to a vehicle body (chassis) or a suspension device. More specifically, the inner arm (45) of the drive motor assembly (40) protrudes outward from the in-wheel motor system (10) through the hub cover hole (32) and is fixed to the vehicle body (chassis) or the suspension device. A bearing (102) is arranged between the outer surface of the second bearing seat (34) and the inner arm (45), so that the wheel hub cover (30) can rotate with respect to the drive motor assembly (40).

[0070] A driven gear (36) is provided on one surface of the outer diameter of the wheel hub cover (30) (i.e., the surface facing the wheel hub (20). The driven gear (36) may be manufactured separately from the wheel hub cover (30) and joined to the wheel hub cover (30) through a joining means such as bolts, splines, and / or welding, or may be formed integrally with the wheel hub cover (30). In one example, the driven gear (36) may be formed as a ring gear of a spiral bevel gear, but is not limited thereto.

[0071] The above-described driven gear (36) is engaged with the driving gear (58) in the direction of the wheel axis. Accordingly, the wheel hub cover (30) receives power from the driving motor assembly (40) and rotates around the wheel axis, and the wheel hub (20) operatively coupled to the wheel hub cover (30) also rotates around the wheel axis by the power. In addition, a bearing (100) is arranged between the first bearing seat (24) and the outer arm (44), and a bearing (102) is arranged between the second bearing seat (34) and the inner arm (45), so that the driving motor assembly (40) is fixed to the chassis, body, or suspension, while the wheel hub (20) and the wheel hub cover (30) can rotate smoothly.

[0072] Since the number of gear teeth of the driven gear (36) is greater than the number of gear teeth of the driving gear (58), the rotational speed thereof is reduced during the process of transmitting power from the driving motor assembly (40) to the wheel hub cover (30). That is, according to the embodiment of the present invention, a reduction ratio required for starting or high-speed driving of the vehicle can be obtained through the driving gear (58) and the driven gear (36) that mesh with each other. Therefore, a compact and lightweight in-wheel motor system (10) can be implemented due to a reduction device with a simple structure.

[0073] As shown in FIGS. 5 and 6, the drive motor assembly (40) is connected to a power source (not shown) such as a battery and a control system (not shown) via a wire (120) to generate power for driving the vehicle, and includes a drive motor (41), a brake (70), a parking brake (80), a funnel (90), and a hydraulic control module (130).

[0074] The drive motor (41) may be an electric motor including a motor housing (42), a stator (46), a rotor (48), a rotor shaft (50), a brake shaft (56), and a resolver (60). The rotor shaft (50) and the brake shaft (56) are operatively connected to each other.

[0075] The motor housing (42) has a hollow cylindrical shape including an open front, side surfaces, and an open rear surface. A front motor cover (52) is coupled to the open front surface using a coupling means such as a bolt, and a rear motor cover (54) is coupled to the open rear surface using a coupling means such as a bolt. A front motor cover hole (53) is formed in the center of the front motor cover (52), and the rotor shaft (50) and the brake shaft (56) can be operatively coupled to each other by passing through the front motor cover hole (53). The inner surface of the front motor cover (52) forming the front motor cover hole (53) acts as a bearing seat, and a bearing (106) is arranged between the inner surface of the front motor cover (52) and the outer surface of the front end of the rotor shaft (50). Similarly, a rear motor cover hole (55) is formed in the center of the rear motor cover (54), and the rear end of the rotor shaft (50) passes through the rear motor cover hole (55). The inner surface of the rear motor cover (54) forming the rear motor cover hole (55) above acts as a bearing seat, and a bearing (104) is arranged between the inner surface of the rear motor cover (54) and the outer surface of the rear end of the rotor shaft (50). By means of the bearings (104, 106), the rotor shaft (50) can rotate smoothly around its central axis.

[0076] The outer arm (44) protrudes from one side of the motor housing (42) toward one side in the direction of the wheel axis and is inserted into the hub hole (23) of the hub disc portion (22), and a bearing (100) is arranged between the first bearing seat (24) of the hub disc portion (22) and the outer surface of the outer arm (44). The inner arm (45) protrudes from the other side of the motor housing (42) toward the other side in the direction of the wheel axis and is inserted into the hub cover hole (32) of the wheel hub cover (30), and a bearing (102) is arranged between the second bearing seat (34) of the wheel hub cover (30) and the outer surface of the inner arm (45). The inner arm (45) protrudes from the wheel hub cover (30) by penetrating the hub cover hole (32), and a knuckle adapter (16) is mounted on the inner arm (45) protruding from the wheel hub cover (30) through a connecting means such as a bolt, and a knuckle (14) is mounted on one side of the knuckle adapter (16) through a connecting means such as a bolt, so that the inner arm (45) is connected to a chassis, a body, or a suspension device through the knuckle adapter (16) and the knuckle (14). Accordingly, the motor housing (42) of the drive motor assembly (40) is fixed to the chassis, the body, or the suspension device, while the wheel hub (20), the wheel hub cover (30), and the tire (12) mounted on the wheel hub (20) can rotate smoothly with respect to the motor housing (42), the chassis, the body, or the suspension device by the bearings (100, 102).

[0077] The above knuckle adapter (16) is mounted on the inner arm (45) on the other side of the bearing (102) and is spaced apart from the wheel hub cover (30). A sealing member (33) is arranged between the knuckle adapter (16) and the wheel hub cover (30) to prevent oil (O) that lubricates and cools the bearing (102) from leaking to the outside of the drive motor assembly (40).

[0078] A wire (120) is arranged inside the inner arm (45). That is, the wire (120) for supplying current to the drive motor (41) or transmitting a control signal is arranged inside the inner arm (45) fixed to the chassis, body, or suspension device, thereby preventing the wire (120) from being twisted or damaged.

[0079] The stator (46) is fixed to the motor housing (42) within the motor housing (42). The stator (46) is connected to a power source via a wire (120) to form a magnetic field, and includes a stator core and a stator coil surrounding the stator core. The structure of the stator (46) is well known to those skilled in the art, so a further detailed description will be omitted.

[0080] The rotor (48) is positioned radially inside the stator (46) with a gap (49) set therebetween. The rotor (48) is configured to rotate by a magnetic field generated by the stator (46). In one example, a permanent magnet may be attached or embedded in the outer diameter of the rotor (48). A drive motor assembly (40) including such a rotor (48) is called a permanent magnet synchronous motor (PMSM). However, it will be understood that the present invention is not limited to the type of the drive motor (41) exemplified in the present specification.

[0081] The rotor shaft (50) is a hollow shaft extending in the axial direction, and the outer surface of the rotor shaft (50) is coupled to the rotor (48) so as to rotate together with the rotor (48). In one example, the rotor (48) may be coupled to the rotor shaft (50) by a spline or a key, but is not limited thereto.

[0082] The front end of the rotor shaft (50) passes through the front motor cover hole (53) of the front motor cover (52), and a bearing (106) is arranged between the inner surface of the front motor cover (52) and the outer surface of the front end of the rotor shaft (50). The rear end of the rotor shaft (50) passes through the rear motor cover hole (55) of the rear motor cover (54), and a bearing (104) is arranged between the inner surface of the rear motor cover (54) and the outer surface of the rear end of the rotor shaft (50).

[0083] The brake shaft (56) is arranged coaxially with the rotor shaft (50), and the rear end of the brake shaft (56) passes through the front motor cover hole (53) of the front motor cover (52), and the front end of the brake shaft (56) crosses the brake (70) and passes through the brake housing hole (73) of the front of the brake housing (72) and protrudes to the outside of the brake housing (72). The front end of the brake shaft (56) protruding from the front of the brake housing (72) is provided with a drive gear (58) that meshes with the driven gear (36). The drive gear (58) may be manufactured separately from the brake shaft (56) and connected to the front end of the brake shaft (56) through a connecting means such as a fixing bolt and / or a spline, or may be formed integrally with the brake shaft (56). The drive gear (58) may be formed as a pinion gear of a spiral bevel gear.

[0084] The rear end of the brake shaft (56) is operatively coupled to the front end of the rotor shaft (50). More specifically, the rear end of the brake shaft (56) is operatively coupled to the front end of the rotor shaft (50) via splines or keys so as to be rotatable together with the rotor shaft (50). For example, splines may be formed on the inner surface of the front end of the rotor shaft (50) and the outer surface of the rear end of the brake shaft (56), respectively, so that the rear end of the brake shaft (56) may be inserted into the front end of the rotor shaft (50) and spline-coupled to each other. However, the operative coupling of the brake shaft (56) and the rotor shaft (50) is not limited thereto, and may include various operative couplings such as key coupling, welding, and adhesion.

[0085] A bearing (108) is arranged between the outer surface of the rear end of the brake shaft (56) and the inner surface of the front motor cover (52), and a bearing (110) is arranged between the outer surface of the front end of the brake shaft (56) and the inner surface of the front end of the brake housing (72). By means of the bearings (108, 110), the brake shaft (56) can rotate smoothly around its central axis.

[0086] In this way, by connecting the brake shaft (56) and the rotor shaft (50) separately rather than forming them as one piece, the shock from the road surface generated when the vehicle is driven or the sudden change in load when the brake (70) is operated are not transmitted to the drive motor (41), thereby improving the durability and lifespan of the drive motor (41).

[0087] When current is supplied to the stator (46) of the drive motor (41), the rotor (48) rotates, and the rotor shaft (50) operatively coupled to the rotor (48) and the brake shaft (56) operatively coupled to the rotor shaft (50) also rotate together with the rotor (48). In this case, the drive gear (58) operatively coupled to the front end of the brake shaft (56) also rotates and transmits driving force to the driven gear (36) meshed with the drive gear (58), and accordingly, the wheel hub (20), the wheel hub cover (30), and the tire (12) mounted on the wheel hub (20) rotate around the wheel axis direction, and the vehicle runs.

[0088] The resolver (60) is configured to measure the rotational speed of the rotor shaft (50), i.e., the rotational speed of the drive motor (41), by generating a change in a physical value (e.g., a change in a magnetic field or a stimulus) corresponding to the rotational speed of the rotor shaft (50). The resolver (60) may include, but is not limited to, a resolver rotor mounted on the rear end of the rotor shaft (50) and a resolver stator mounted on the rear motor cover (54).

[0089] FIG. 7 is an exploded view of a brake (70) and a parking brake (80) of a drive motor assembly (40) according to an embodiment of the present invention, FIG. 8 is a perspective view of a brake (70) and a parking brake (80) according to an embodiment of the present invention, and FIG. 9 shows the operation of a parking brake (80) according to an embodiment of the present invention.

[0090] As shown in FIGS. 5 to 9, the brake (70) is mounted on the brake shaft (56) to implement braking by slowing down the rotation of the brake shaft (56). The brake (70) includes a disc hub (71), a brake housing (72), a friction disc pack (74), and a piston (76).

[0091] The disc hub (71) is operatively coupled to the outer surface of the brake shaft (56) through splines or keys and rotates together with the brake shaft (56).

[0092] The brake housing (72) has a cylindrical shape with an open rear end, and the rear end of the brake housing (72) functions as a fixed element by being connected to the front motor cover (52) through a connecting means such as a bolt. The front of the brake housing (72) is generally shaped like a disk, and a brake housing hole (73) is formed in the center, so that the front end of the brake shaft (56) passes through the brake housing hole (73) and protrudes to the outside of the brake housing (72). A bearing (110) is arranged between the outer circumferential surface of the front end of the brake shaft (56) and the inner circumferential surface of the front of the brake housing (72).

[0093] A friction disc pack (74) is mounted between the outer surface of the disc hub (71) and the inner surface of the brake housing (72) and is configured to selectively connect the disc hub (71) to the brake housing (72). More specifically, the friction disc pack (74) includes a plurality of first friction discs operatively connected to the outer surface of the disc hub (71), and a plurality of second friction discs alternately arranged with the plurality of first friction discs and operatively connected to the inner surface of the brake housing (72), and the plurality of first and second friction discs rub against each other by an operating force applied through a piston (76) and operatively connect the disc hub (71), i.e., the brake shaft (56), to the brake housing (72). Thereby, the rotational speed of the brake shaft (56) is reduced. If the plurality of first and second friction discs are completely engaged with each other by friction, the rotation of the brake shaft (56) stops, and accordingly, the vehicle stops. A convex-shaped power lever shoe (75) may be provided on the rear side of the friction disc pack (74).

[0094] The piston (76) is generally disk-shaped and is arranged to be axially movable between the front surface of the brake housing (72) and the front surface of the friction disc pack (74) of the brake shaft (56). A piston chamber (78) is formed between the piston (76) and the front surface of the brake housing (72). When oil (O) is supplied to the piston chamber (78), the piston (76) moves axially rearward by the oil (O) and pushes the first and second friction discs axially rearward. Then, the rear surface of the friction disc pack (74) is supported by the front motor cover (52), and the first and second friction discs begin to rub against each other. Accordingly, the rotational speed of the brake shaft (56) begins to decrease. If sufficient oil pressure is supplied to the piston chamber (78), the piston (76) frictionally engages the first and second friction discs, thereby stopping the brake shaft (56). Meanwhile, when the oil (O) supplied to the piston chamber (78) is discharged from the piston chamber (78), the piston (76) moves axially forward, and the first and second friction discs that were frictionally engaged begin to disengage. To facilitate the axial forward movement of the piston (76), a return spring may be arranged between the brake housing (72) and the piston (76). When the oil (O) is completely discharged from the piston chamber (78), the first and second friction discs move to their initial positions and do not rub against each other. Accordingly, the braking of the brake shaft (56) is released.

[0095] As illustrated in FIGS. 5 to 9, the parking brake (80) is configured to mechanically frictionally engage a friction disc pack (74) to perform braking during parking or to function as an auxiliary brake means. The parking brake (80) includes an actuator (82), a plunger link (84), and a power lever (86).

[0096] The actuator (82) is located outside the motor housing (42) and can be fixedly mounted on the outer surface of the motor housing (42) using a connecting means such as a bolt. The actuator (82) includes an actuator plunger (83). The actuator (82) is configured to push the actuator plunger (83) when parking and to pull the actuator plunger (83) in other cases.

[0097] The plunger link (84) is hinge-connected to the tip of the actuator plunger (83). When the actuator (82) pushes the actuator plunger (83), the plunger link (84) is also pushed together, and the first and second friction discs are frictionally engaged (the friction disc pack (74) is engaged) through the power lever (86). Conversely, when the actuator (82) pulls the actuator plunger (83), the plunger link (84) is also pulled together, and the first and second friction discs are released (the friction disc pack (74) is released).

[0098] The power lever (86) is generally circular in shape and has a lever hole (85) formed in the center. The power lever (86) is mainly arranged inside the brake housing (72), and the brake shaft (56) passes through the lever hole (85). One side of the power lever (86) protrudes radially and is hinge-connected to the front motor cover (52) via a hinge pin (88). Accordingly, the power lever (86) can pivot based on the hinge pin (88). The other side, which is opposite to one side of the power lever (86), protrudes radially and protrudes outward from the brake housing (72) and is hinge-connected to the front end of the plunger link (84). Accordingly, when the actuator (82) pushes the plunger link (84) through the actuator plunger (83), the plunger link (84) rotates the power lever (86) clockwise in the drawing with respect to the hinge pin (88) to push the friction disc pack (74) axially forward. Then, the front portion of the friction disc pack (74) is axially supported by the piston (76) and the front surface of the brake housing (72), so that the friction disc pack (74) is frictionally engaged. Accordingly, the brake shaft (56) and the drive motor assembly (40) are braked. In contrast, when the actuator (82) pulls the plunger link (84), the plunger link (84) rotates the power lever (86) counterclockwise in the drawing with respect to the hinge pin (88). Then, the friction disc pack (74) that was frictionally engaged moves axially rearward to its original position, thereby releasing the friction disc pack (74). Accordingly, the braking of the brake shaft (56) and the drive motor assembly (40) is released.

[0099] Meanwhile, since the friction disc pack (74) is pressurized by rotating the power lever (86) based on the hinge pin (88), the position of the friction disc pack (74) receiving the operating force of the power lever (86) changes according to the rotation of the power lever (86), and the operating force may be concentrated at a specific position of the friction disc pack (74). In order to prevent this problem, a power lever shoe (75) having a gently convex shape is provided on the rear side of the friction disc pack (74), and a power lever shoe groove (87) having a gently concave shape is provided at a position of the power lever (86) corresponding to the power lever shoe (75).

[0100] Since the friction disc pack (74) is engaged by rotating the power lever (86) based on the hinge pin (88), the operating force of the power lever (86) is multiplied by the lever principle. If the distance from the hinge pin (88) to the power lever shoe (75) is L1, the distance from the power lever shoe (75) to the connection point of the plunger link (84) and the power lever (86) is L2, the force applied by the actuator (82) to the power lever (86) is F1, and the operating force applied by the power lever (86) to the friction disc pack (74) is F2, then F2 satisfies the following equation.

[0101] (L1 + L2) * F1 = L1 * F2

[0102] F2 = F1 * (L1 + L2) / L1

[0103] Therefore, F2 is multiplied by (L1 + L2) / L1.

[0104] In an embodiment of the present invention, by using the same friction disc pack (74) for the operation of the brake (70) and the parking brake (80), the weight and cost of the in-wheel motor system (10) can be reduced, while a more compact in-wheel motor system (10) can be implemented.

[0105] Meanwhile, in this embodiment, a case where a power lever (86) is used as a power boosting device of an actuator (82) is shown, but the present invention is not limited thereto, and includes a case where a power boosting device known to those skilled in the art, such as a wedge (not shown) or a ball ramp (not shown) operated by an actuator is used. That is, this embodiment includes a case where the operating force of the actuator is boosted using a device such as a wedge or a ball ramp to pressurize the friction disk pack (74).

[0106] The funnel (90) may be mounted on the rear of the rear motor cover (54) and positioned at the rearmost position in the drive motor assembly (40). However, the present invention is not limited thereto, and the position of the funnel (90) may vary depending on the mounting position of the drive motor assembly (40) within the space of the wheel hub (20). For example, when the drive motor assembly (40) is mounted close to horizontal to the ground, it may be positioned at a position where it is easy to collect oil from the side of the motor housing (42).

[0107] The above funnel (90) is formed in a cylindrical or square shape with one side open so as to easily receive oil by oil churning when the wheel hub (20) and the wheel hub cover (30) rotate. The oil (O) collected in the funnel (90) by oil churning flows into the interior of the drive motor assembly (40) and can cool the drive motor (41) and the brake (70). The cooling of the drive motor (41) and the brake (70) by oil churning will be described in more detail below.

[0108] FIG. 10 is a perspective view of a hydraulic control module (130) of an in-wheel motor system (10) according to an embodiment of the present invention.

[0109] As illustrated in Fig. 10, the hydraulic control module (130) can hydraulically actuate or release the brake (70). In addition, the hydraulic control module (130) can supply oil for cooling the drive motor (41) and the brake (70) when necessary. The hydraulic control module (130) is mounted in the motor housing (42) and includes an oil filter (132), an oil pump (136), and a control block (138).

[0110] The oil filter (132) is designed to filter out foreign substances present in the oil. An oil absorption portion (133) is formed at one end (e.g., the lower end) of the oil filter (132), and an intake pipe (142) is connected to the other end of the oil filter (132). One end of the oil filter (132) provided with the oil absorption portion (133) is always immersed in oil (O) within the wheel hub (20), so that the oil (O) flows into the oil filter (132) through the oil absorption portion (133), passes through the oil filter (132), and then flows out through the intake pipe (142).

[0111] The oil pump (136) includes a suction port and a discharge port connected to the suction pipe (142). In addition, the oil pump (136) includes an oil pump motor (134). When the oil pump motor (134) operates, the oil pump (136) is configured to suck oil (O) inside the wheel hub (20) through the oil filter (132), the suction pipe (142), and the suction port, and to use the sucked oil (O) to generate brake operating pressure or cooling flow rate for the drive motor (41) and the brake (70) according to the braking state of the vehicle, and to discharge the oil (O) through the discharge port.

[0112] The control block (138) is connected to the discharge port of the oil pump (136) and includes a solenoid valve (140). In addition, the control block (138) is provided with first and second outlets (144, 146), and the first and second outlets (144, 146) are connected to the motor housing (42). The first outlet (144) is an outlet through which oil for operating the brake (70) is discharged, and the second outlet (146) is an outlet through which oil for cooling the drive motor (41) and the brake (70) is discharged. Within the control block (138), flow paths connecting the discharge port to the first and second outlets (144, 146) are formed, and the solenoid valve (140) is configured to control the connection or blocking of the flow paths and the pressure and flow rate of the oil (O) discharged through the first and second outlets (144, 146). That is, the solenoid valve (140) is configured to discharge the hydraulic pressure generated by the oil pump (136) and to control the flow rate of oil (O) discharged through the outlet. If necessary, a plurality of solenoid valves (140) may be used so that each of the plurality of solenoid valves (140) performs a different function.

[0113] The above hydraulic control module (130) further includes a temperature sensor (148) and a pressure sensor (150). The temperature sensor (148) detects the temperature of oil (O) sucked into the oil filter (132), and the pressure sensor (150) detects the hydraulic pressure generated by the oil pump (136). Based on the temperature and hydraulic pressure of the oil (O), the hydraulic control module (130) can control the operating pressure of the brake (70) or the cooling flow rate of the drive motor (41) and the brake (70).

[0114] The above in-wheel motor system (10) further includes a passage for supplying operating pressure to the brake (70). FIG. 11 is a cross-sectional view of a drive motor assembly of the in-wheel motor system according to an embodiment of the present invention, showing a brake operating oil passage, and FIG. 12 shows a path through which operating oil is supplied to the piston chamber in FIG. 11. As shown in FIGS. 11 and 12, the passage for supplying operating pressure to the brake (70) includes a connecting pipe (152) and a brake operating oil passage (154). The brake operating oil passage (154) is formed in the brake housing (72) and is connected to the piston chamber (78). The connecting pipe (152) connects the motor housing (42) and the brake housing (72). More specifically, the connecting pipe (152) connects the first outlet connecting hole (145) formed in the motor housing (42) and the brake operating oil passage (154) of the brake housing (72). When the oil pump (136) generates the operating pressure of the brake (70), the operating pressure is discharged to the first outlet (144) under the control of the solenoid valve (140) of the control block (138). Then, the operating pressure is supplied to the piston chamber (78) through the first outlet connecting hole (145), the connecting pipe (152), and the brake operating oil passage (154), and the piston (76) pressurizes the friction disc pack (74) against the front motor cover (52) to frictionally engage the friction disc pack (74). Accordingly, the brake shaft (56) is operatively connected to the brake housing (72) to implement braking.

[0115] The above in-wheel motor system (10) further includes a cooling device for cooling the drive motor (41) and the brake (70). The cooling device circulates oil (O) within the wheel hub (20) to cool the drive motor (41) and the brake (70), and the oil (O) that has been heated while cooling the drive motor (41) and the brake (70) comes into contact with the wheel hub (20) and the wheel hub cover (30) by churning, and the heat of the oil (O) transferred to the wheel hub (20) and the wheel hub cover (30) is cooled by the air flow around the wheel generated when the vehicle is driven. The wheel hub (20) and the wheel hub cover (30) may be provided with a plurality of cooling fins (not shown) to improve cooling performance.

[0116] In an embodiment of the present invention, the drive motor (41) and the brake (70) are cooled using oil churning and a hydraulic control module (130).

[0117] Fig. 13 shows the path of oil by oil churning for cooling the drive motor (41), and Fig. 14 shows the path of oil by oil churning for cooling the brake (70). As shown in Fig. 13, oil (O) by oil churning is collected in a funnel (90). A funnel oil passage (159) is formed on the opposite side of one side of the funnel (90) on which an opening is formed, and the funnel oil passage (159) is connected to a rear motor cover oil passage (161) formed on a rear motor cover (54), so that a portion of the oil (O) collected in the funnel (90) by oil churning flows into the motor housing (42) through the funnel oil passage (159) and the rear motor cover oil passage (161).

[0118] An oil distributor (158) is provided inside the motor housing (42) corresponding to the rear motor cover oil passage (161), and the oil distributor (158) is configured to send the oil (O) to the outer surface of the stator (46) and the gap (49) between the rotor (48) and the stator (46). More specifically, a plurality of cooling channels (156) are formed between the motor housing (42) and the stator (46), and a first passage (157) communicating with the cooling channels (156) is formed in the oil distributor (158). In addition, a second passage (163) communicating with the gap (49) between the rotor (48) and the stator (46) is formed in the oil distributor (158). Accordingly, a portion of the oil (O) that has flowed into the oil distributor (158) flows into the cooling channel (156) through the first passage (157), and the remaining portion of the oil (O) that has flowed into the oil distributor (158) flows into the gap (49) between the rotor (48) and the stator (46) through the second passage (163). The oil (O) flows down due to its own weight and cools the stator (46) and the rotor (48).

[0119] A first cooling oil outlet (160) is formed on the front of the motor housing (42). Oil (O) that cools the stator (46) and the rotor (48) and moves to the front of the motor housing (42) collects on the front motor cover (52) and is discharged to the outside of the motor housing (42) through the first cooling oil outlet (160). The oil (O) collects on the lower part of the wheel hub (20), and is cooled (air-cooled) through the wheel hub (20) and the wheel hub cover (30) by oil churning, and moves into the funnel (90) or is sucked into the oil filter (132) by the operation of the oil pump (136).

[0120] As illustrated in Fig. 14, the funnel oil passage (159) formed on the opposite surface of the funnel (90) is also connected to the rotor shaft oil passage (162) formed in the rotor shaft (50). In addition, the rotor shaft oil passage (162) is connected to the brake shaft oil passage (164) formed in the brake shaft (56), and the brake shaft oil passage (164) is connected to the disc hub oil passage (166) formed in the disc hub (71). Therefore, a portion of the oil (O) collected in the funnel (90) by oil churning flows downward through the rotor shaft oil passage (162) and the brake shaft oil passage (164) by its own weight, and passes through the friction disc pack (74) through the disc hub oil passage (166) by centrifugal force. A plurality of second coolant outlets (168) are formed on the side of the brake housing (72) so that the oil (O) that passes through the friction disc pack (74) and cools the friction disc pack (74) is discharged to the outside of the brake housing (72) through the second coolant outlets (168). The oil (O) is collected in the lower space of the wheel hub (20), cooled (air-cooled) through the wheel hub (20) and the wheel hub cover (30) by oil churning, and moves into the funnel (90) or is sucked into the oil filter (132) by the operation of the oil pump (136).

[0121] In the above, for the convenience of explanation, the state in which the oil (O) collected in the funnel (90) by oil churning flows to the drive motor (41) and the state in which it flows to the brake (70) are shown separately through FIGS. 13 and 14, but in reality, the cooling of the drive motor (41) and the brake (70) is performed simultaneously. That is, the oil collected in the funnel (90) is simultaneously supplied to the cooling channel (156), gap (49), rotor shaft oil passage (162) and brake shaft oil passage (164) of the drive motor (41).

[0122] Fig. 15 shows the oil path by the hydraulic control module (130) for cooling the drive motor (41), and Fig. 16 shows the oil path by the hydraulic control module (130) for cooling the brake (70).

[0123] As illustrated in Fig. 15, a cooling oil supply passage (170) is formed in the motor housing (42), and the cooling oil supply passage (170) communicates the second outlet (146), the second outlet connection hole (147), and the rear motor cover oil passage (161) with each other. When the oil pump (136) generates cooling flow for cooling, the cooling flow is discharged to the second outlet (146) under the control of the solenoid valve (140) of the control block (138). Then, the cooling flow is introduced into the motor housing (42) through the second outlet connection hole (147), the cooling oil supply passage (170), and the rear motor cover oil passage (161).

[0124] The cooling flow introduced into the motor housing (42) flows into the oil distributor (158). A portion of the cooling flow that has flowed into the oil distributor (158) flows into the cooling channel (156) through the first passage (157), and a portion of the cooling flow that has flowed into the oil distributor (158) flows into the gap (49) between the rotor (48) and the stator (46) through the second passage (163). The cooling flow flows down due to its own weight and cools the stator (46) and the rotor (48). Thereafter, the cooling flow is discharged to the outside of the motor housing (42) through the first cooling oil outlet (160).

[0125] As shown in Fig. 16, the rear motor cover oil passage (161) is also connected to a rotor shaft oil passage (162) formed within the rotor shaft (50). In addition, the rotor shaft oil passage (162) is connected to a brake shaft oil passage (164), and the brake shaft oil passage (164) is connected to a disc hub oil passage (166). When the oil pump (136) generates a cooling flow for cooling, the cooling flow is discharged to the second outlet (146) under the control of the solenoid valve (140) of the control block (138). Then, the cooling flow flows into the rotor shaft oil passage (162) through the second outlet connection hole (147), the cooling oil supply passage (170), and the rear motor cover oil passage (161), flows through the rotor shaft oil passage (162) and the brake shaft oil passage (164), and passes through the friction disc pack (74) through the disc hub oil passage (166) by centrifugal force. Thereafter, the cooling flow is discharged to the outside of the brake housing (72) through the second cooling oil outlet (168).

[0126] In the above, for the convenience of explanation, the state in which the cooling flow rate by the hydraulic control module (130) is supplied separately to the drive motor (41) and the brake (70) is shown through FIGS. 15 and 16, but in reality, the oil supply and cooling to the drive motor (41) and the brake (70) can be performed simultaneously.

[0127] Figures 17 and 18 illustrate the oil level within a wheel hub (20) when the drive motor assembly (40) is positioned vertically or nearly vertically with respect to the ground in one embodiment of the present invention. Figure 17 illustrates the oil level within the wheel hub when the vehicle is stopped or driving at low speed, and Figure 18 illustrates the oil level within the wheel hub when the vehicle is driving.

[0128] As illustrated in Fig. 17, when the brake (70) is positioned so as to be below the driving motor assembly (40), the brake (70) is immersed in the oil (O) when the vehicle is stopped or driving at low speed, so that the heat generated in the brake (70) can be quickly transferred to the oil (O). More specifically, the inside of the wheel hub (20) is filled with oil (O) up to the first oil level (O.L1), and the first oil level (O.L1) is positioned higher than the top of the brake (70). Therefore, when the centrifugal force is not applied or is small (for example, when the vehicle is stopped or driving at low speed), the brake (70) is completely immersed in the oil (O), so that the heat generated in the brake (70) can be quickly transferred to the oil (O).

[0129] As illustrated in Fig. 18, when the vehicle is driven, the oil (O) is positioned in a circular shape along the inner diameter of the wheel hub (20) by centrifugal force, so that the oil level is lowered to the second oil level (O.L2), and the brake (70) is exposed to the air. This minimizes the drag loss of the friction disc pack (74) due to the viscosity of the oil (O), thereby increasing the driving efficiency of the in-wheel motor system (10).

[0130] In the embodiment of the present invention described above, an example is given in which the brake (70) of the drive motor assembly (40) is positioned so that it is vertical or nearly vertical downward with respect to the ground, so that the churning oil collected in the funnel (90) is supplied to the cooling path of the drive motor (41) and the cooling path of the brake (70) by its own weight, thereby cooling the drive motor (41) and the brake (70). However, the embodiment of the present invention is not limited thereto.

[0131] For example, the drive motor assembly (40) may be placed horizontally or nearly horizontally with respect to the ground, and the opening of the funnel (90) may be formed vertically or nearly vertically in an upward direction away from the ground, so that oil collected in the funnel (90) by churning may flow into the cooling passage inside the drive motor (41) and the brake (70) by its own weight, thereby cooling the drive motor (41) and the brake (70). It should be construed that the embodiments of the present invention also include such examples.

[0132] In an embodiment of the present invention, when the temperature of the oil inside the wheel hub (20) is low, such as during low-speed or coasting driving, the drive motor (41) and the brake (70) are naturally cooled only by churning of the oil, and when the temperature of the oil rises, such as during high-speed driving or sudden braking, the hydraulic control module (130) is operated to supply additional cooling oil to the drive motor (41) and the brake (70), thereby forcibly cooling them. Accordingly, the power consumption of the hydraulic control module (130) can be reduced while also improving cooling performance.

[0133] In an embodiment of the present invention, the oil that cools the drive motor (41) and the brake (70) is collected into the lower space of the wheel hub (20) through the first and second cooling oil discharge ports (160, 168), and the oil collected in the lower space of the wheel hub (20) rotates together with the wheel hub (20) and the wheel hub cover (30) due to viscosity, is cooled by the air flowing around the wheel, and is circulated back to the funnel (90) or the hydraulic control module (130).

[0134] Therefore, in embodiments of the present invention, unlike conventional in-wheel motor systems, an oil cooling device provided on a vehicle body can be omitted, so that hydraulic hoses connecting the in-wheel motor and the cooling device can be deleted, thereby implementing a by-wire in-wheel motor system that can be driven and controlled using only wires.

[0135]

[0136] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and includes all changes that can be easily modified by a person having ordinary skill in the art to which the invention pertains and are recognized as equivalent.

Claims

1. A wheel hub comprising a hub disc portion defining one side and a hub cylindrical portion extending in the direction of the wheel axis from an outer diameter end of the hub disc portion, and having an opposite side of the one side, which is an open side; A wheel hub cover coupled to the other surface of the wheel hub and including a driven gear provided on the outer diameter; and A drive motor assembly disposed within the wheel hub and configured to provide driving force; , and the drive motor assembly comprises A drive motor comprising a cylindrical motor housing, a stator fixed within the motor housing and generating a magnetic field, a rotor rotatably disposed radially inside the stator with a set gap from the stator, a rotor shaft coupled to the rotor and rotating together with the rotor and extending in the axial direction, and a brake shaft including a rear end operatively coupled to a front end of the rotor shaft and a front end provided with a drive gear meshed with the driven gear. A brake comprising a brake housing mounted on a brake shaft and including a front and side surfaces, a friction disc pack disposed within the brake housing and selectively connecting the brake housing and the brake shaft, and a piston disposed at the front of the friction disc pack and forming a piston chamber between the front surface of the brake housing and the front surface of the friction disc pack to pressurize and engage the friction disc pack toward the drive motor, and A parking brake comprising a power lever arranged at the rear end of a friction disc pack and configured to pressurize the friction disc pack toward a piston, and an actuator configured to apply a force for pressing the friction disc pack to the power lever. In-wheel motor system including.

2. In paragraph 1, The rotor shaft is composed of a hollow shaft, An in-wheel motor system in which the rear end of the brake shaft is inserted into the front end of the rotor shaft and spline-coupled.

3. In paragraph 2, The above motor housing includes an open front, side, and open rear, A front motor cover is attached to the above open front, and a rear motor cover is attached to the above open rear. The front of the above front motor cover is coupled with a brake housing, An in-wheel motor system in which the rotor shaft and the brake shaft are spline-coupled to each other through the front motor cover.

4. In paragraph 3, A hub hole is formed in the center of the above hub disc, and a hub cover hole is formed in the center of the wheel hub cover. The above motor housing further includes an outer arm that protrudes from one side in the direction of the wheel axis and is inserted into a hub hole of the hub disc, and an inner arm that protrudes from the other side in the direction of the wheel axis and penetrates a hub cover hole. An in-wheel motor system in which bearings are arranged between the inner surface of the outer arm and the hub disc portion and between the inner arm and the inner surface of the wheel hub cover.

5. In paragraph 3, The brake further comprises a disc hub operatively coupled to the brake shaft so as to rotate with the brake shaft; An in-wheel motor system in which a portion of the friction disc pack is spline-coupled to a disc hub and another portion is spline-coupled to a brake housing, such that a portion of the friction disc pack and the other portion are frictionally coupled to each other by a force acting in the axial direction of a brake shaft.

6. In paragraph 5, The piston pressurizes the friction disc pack against the front motor cover by the operating pressure supplied to the piston chamber, thereby frictionally engaging the friction disc pack. The above-mentioned power lever is an in-wheel motor system that receives force from an actuator and presses the friction disc pack against the front of the brake housing to frictionally engage it.

7. In paragraph 6, The above parking brake further includes a plunger link hingeably connected to the actuator and the power lever to transmit the force of the actuator to the power lever, An in-wheel motor system in which one side of the power lever is hingedly connected to the front motor cover, the other side of the power lever protrudes outside the brake housing, and the plunger link is connected.

8. In paragraph 7, An in-wheel motor system in which a convex-shaped boost lever shoe is provided on the rear side of the friction disc pack, and a concave-shaped boost lever shoe groove is provided at a position of the boost lever corresponding to the boost lever shoe.

9. In paragraph 5, The inside of the wheel hub and wheel hub cover that are joined together are filled with oil, The above in-wheel motor system further includes a funnel having one side opened to receive oil by oil churning when the wheel hub and the wheel hub cover are rotated and coupled to each other, and is mounted on the rear of the rear motor cover.

10. In paragraph 9, An in-wheel motor system further comprising a hydraulic control module configured to generate operating pressure and supply it to the brake or to generate cooling flow for cooling and supply it to the drive motor and the brake.

11. In paragraph 10, The above hydraulic control module An oil pump configured to suck oil within a wheel hub to generate operating pressure or cooling flow; A control block provided with first and second exits; and At least one solenoid valve configured to select at least one of the first and second outlets and to control the pressure and flow rate of oil discharged through the selected outlet; An in-wheel motor system including:

12. In paragraph 11, The first outlet is an in-wheel motor system that supplies oil to the piston chamber through a connecting pipe connected to the first outlet and a brake operating oil passage formed in the brake housing.

13. In paragraph 11, The second outlet is an in-wheel motor system that supplies cooling fluid into the motor housing and the rotor shaft through a cooling oil supply passage formed in the motor housing and a rear motor cover oil passage formed in the rear motor cover.

14. In paragraph 13, An oil distributor is provided inside the motor housing corresponding to the rear motor cover oil passage above. An in-wheel motor system wherein the above oil distributor is configured to send the cooling flow to the cooling channel between the motor housing and the stator and the gap between the rotor and the stator.

15. In paragraph 14, An in-wheel motor system in which the cooling flow passing through the cooling channel between the motor housing and the stator and the gap between the rotor and the stator is discharged to the outside of the motor housing through the first cooling oil outlet formed at the front part of the motor housing.

16. In paragraph 13, An in-wheel motor system where cooling flow supplied into the rotor shaft is supplied to the friction disc pack through the interior of the brake shaft and the disc hub.

17. In paragraph 16, An in-wheel motor system in which the cooling fluid passing through the friction disc pack is discharged to the outside of the brake housing through a second cooling fluid outlet formed on the side of the brake housing.

18. In paragraph 13, An in-heel motor system in which a funnel oil passage is formed on the opposite side of one side of the funnel, and the funnel oil passage is connected to the rear motor cover oil passage and the rotor shaft.

19. In paragraph 9, An in-wheel motor system in which the above drive motor assembly is positioned so that the brake is close to the ground, so that oil collected by the funnel flows into the interior of the drive motor and brake by its own weight to cool the drive motor and brake.

20. In paragraph 19, An in-wheel motor system in which the brakes are immersed in oil within the wheel hub when the vehicle is stopped or driving at low speeds, and exposed to the air when driving, depending on the position of the brakes and the setting of the oil level.

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