Wheel motor unit

Abstract

To provide a wheel motor unit which constitutes a rational drive part inside a wheel and is superior in steering stability.SOLUTION: A wheel motor unit U includes: a housing H to which an axle Xt supporting a wheel of a vehicle is mounted and which is supported by a vehicle body; and a plurality of motors M mounted to the housing H. In the wheel motor unit U, each of the motors M performs any of a steering function of changing a posture of the axle Xt, or a drive function of rotating the axle Xt, or a braking function of regulating rotation of the axle Xt. Further, extension directions of rotation axes of the motors M are configured to be in parallel to each other.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The wheel motor unit of the present invention has a housing that is supported by a vehicle body and has an axle, and this housing is provided with a plurality of motors that individually perform the steering function, driving function or braking function of the axle. [Background technology]

[0002] Conventionally, an example of such a wheel motor unit is shown in Patent Document 1 (see

[0010] to

[0011] and FIG. 1).

[0003] In this steering module 10, a steering shaft 12 is fixed to a fixed support part 14 provided on the vehicle body, and a swingable main body 18 is supported on the steering shaft 12 so as to be capable of swinging in a steerable manner. A wheel support part 20 is attached to the exterior of the swingable main body 18 and supports the rotation of wheels 110. The swingable main body 18 is freely steerable with respect to the steering shaft 12 by the drive of a steering motor unit 22. In this conventional technology, in particular, the steering motor unit 22 applies torque to the steering shaft 12 so as to maintain the straight-ahead state of the wheels 110.

[0004] This technology can improve the degree of freedom in designing the steering module 10. For example, changing the position of the steering shaft 12 of the steering module 10 increases the scrub radius. As a result, torque is generated around the steering shaft 12 when the vehicle is traveling, making the direction of the wheels unstable.

[0005] Therefore, in the conventional technology, the steering motor unit applies a torque to the steering shaft 12 to keep the wheels moving straight. This increases the steering stability of the wheels. This reduces the need to shorten the scrub radius, and increases the design freedom of the steering module 10, such as by expanding the allowable range of the installation position of the steering shaft 12. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] WO2021 / 044469 A1 publication Summary of the Invention [Problem to be solved by the invention]

[0007] In the above-mentioned conventional steering module 10, the wheel steering motor unit 22 is arranged inside the wheel 110, thereby saving space. However, since the steering shaft 12 is installed in a state where it protrudes to the side of the wheel 110, it is necessary to apply torque to the steering shaft 12 in order to maintain the steering stability of the wheel. Therefore, a torque generating mechanism is necessary for this purpose, and the configuration of the steering module 10 becomes complicated and large.

[0008] In addition, because the steering shaft 12, i.e., the kingpin, is offset to the side of the tire, a certain steering resistance is generated during steering of the wheel according to the distance from the intersection of the extension of the kingpin and the road surface to the ground contact position of the wheel. Therefore, there was a risk that the durability of the steering module 10 would be impaired due to the wear of each component of the steering module 10, causing rattling.

[0009] As described above, conventional wheel motor units still have problems to be solved, and there has been a demand for a wheel motor unit that has a rational drive section inside the wheel and provides excellent steering stability. [Means for solving the problem]

[0010] (Features) The wheel motor unit according to the present invention has the following characteristic configuration: a housing to which an axle supporting a wheel of a vehicle is attached and which is supported by a vehicle body; a plurality of motors attached to the housing; Each of the motors performs either a steering function for changing the attitude of the axle, a driving function for rotating the axle, or a braking function for restricting the rotation of the axle, The rotation shafts of the motors extend in parallel to each other.

[0011] (effect) If the rotational axes of all the motors are parallel, as in this configuration, the configuration of the mechanism connected to the drive shaft of the motor can be set rationally. For example, if each motor is used as a separate functional part, if the axial directions are parallel, each accessory can be installed in the space on the same side of the motor. As a result, the accessories are less likely to interfere with each other, making the device configuration easier.

[0012] Furthermore, when it is desired to use a plurality of motors in cooperation for driving, for example, if the axial directions of the motors are parallel, the structure of the mechanism for extracting rotational force can be simplified.

[0013] Furthermore, the direction in which the motor body is attached or the direction in which various gears are attached to the drive shaft of the motor is often along the direction of the drive shaft. Therefore, with this configuration, assembly and maintenance of the wheel motor unit can be performed efficiently.

[0014] (Features) In the wheel motor unit according to the present invention, the housing can be configured so that the entire housing fits within the inner diameter of the wheel of the vehicle.

[0015] (effect) This configuration makes the wheel motor unit extremely compact, greatly expanding the design freedom of the wheel support structure, which in turn allows for more space to be secured in the vehicle body, simplifies the installation of various auxiliary devices in the vehicle body, and increases the effective utilization of the vehicle, such as expanding the living space for personnel.

[0016] Furthermore, since the entire housing, including the motor with steering function, fits within the inner diameter of the wheel, the intersection point between the extension of the steering shaft and the ground can be brought closer to the point where the wheel touches the ground. In other words, the scrub radius is smaller and no unnecessary resistance is generated during steering. This allows the steering motor to be configured more compactly, resulting in a more rational wheel motor unit.

[0017] (Features) In the wheel motor unit of the present invention, a gear train that transmits the driving rotation of the output shaft of the motor can be provided in the housing, and one of the meshing gears can be provided with a biasing portion that presses the other gear toward the other gear.

[0018] (effect) The motors of this configuration are attached to the housing in the same direction, which is parallel to the direction in which the output shafts extend. Therefore, the position of each output shaft depends on the machining position of the bearing parts provided on the wall of the housing. In that case, if there is a machining error, the meshing state between the gears is not necessarily optimal. Therefore, in this configuration, one of the gears is made movable in a direction perpendicular to the axial direction, and a biasing part is provided that presses one gear against the other gear.

[0019] By providing a biasing portion as in this configuration, rattle does not occur when the drive is transmitted between the gear trains, making it possible to drive smoothly and quietly. Furthermore, as a result of suppressing rattle, the gears are kept in proper contact with each other, preventing problems such as uneven wear of the gears and reduced durability.

[0020] (Features) In the wheel motor unit of the present invention, a link is provided between a left housing provided on the left wheel as the housing, and a right housing provided on the right wheel as the housing, and it is convenient that the motor provided in the left housing or the right housing and performing the steering function, the driving function or the braking function is configured to perform the steering function, the driving function or the braking function for the other wheel.

[0021] (effect) With this configuration, a single motor installed on either the left or right wheel can operate the wheel on the opposite side via a link, which allows for a more streamlined device configuration, such as reducing the number of motors installed on the entire vehicle.

[0022] In addition, the space created by the simplification in the motor mounting location can be used to add a motor for driving functions, for example, to one of the left and right sides, thereby enhancing various functions of the vehicle as a whole. [Brief description of the drawings]

[0023] [Figure 1] FIG. 1 is an external view of a vehicle using a wheel motor unit according to a first embodiment; [Diagram 2] FIG. 1 is a front view showing the configuration of a wheel motor unit; [Diagram 3] FIG. 3 is a cross-sectional view showing the configuration of a drive unit provided in the wheel motor unit; [Figure 4] FIG. 3 is a cross-sectional view showing a configuration of a braking unit provided in a wheel motor unit; [Diagram 5] FIG. 1 is a cross-sectional view showing a configuration of a steering unit provided in a wheel motor unit; [Figure 6] 1 is a cross-sectional view showing a configuration example of a housing of a wheel motor unit; [Figure 7] FIG. 1 is an explanatory diagram showing a configuration example of a wheel motor unit; [Figure 8] FIG. 11 is a cross-sectional view showing a configuration example of a wheel motor unit according to a second embodiment; [Figure 9] FIG. 13 is an explanatory diagram showing a configuration example of a wheel motor unit according to a third embodiment; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] [First embodiment] (overview) The wheel motor unit U according to the present invention (hereinafter simply referred to as "unit U") is used in a vehicle V such as a small electric low-speed vehicle as shown in FIG. 1, and is configured so that a drive motor M1 and a brake motor M2 of the vehicle V are arranged inside the wheel Ta of the wheel T as shown in FIG. 2. This allows each wheel T to be rotated and braked, and also steers the wheel T. By using the wheel motor unit U according to the present invention, independent control of the four wheels is possible, and various driving states such as diagonal driving, extremely small radius turning, and even on-the-spot turning can be obtained in addition to normal straight-line driving and turning driving. In addition, a large cargo space can be secured in the vehicle body Va, and the transport capacity can be increased, and automatic driving with various driving routes set is also possible. Hereinafter, a first embodiment of the wheel motor unit U will be described with reference to FIGS. 1 to 7.

[0025] 2(a) and 2(b), the unit U according to the present invention has a housing H interposed between the vehicle body Va and the wheels T, and an axle Xt supporting the wheels T is attached to the center of the housing H. The unit U has multiple functions, such as a steering function for changing the attitude of the axle Xt, a driving function for rotating the axle Xt, and a braking function for restricting the rotation of the axle Xt. To perform these functions, a motor M corresponding to each purpose is attached to the housing H.

[0026] 2 shows an example in which four motors M are provided. Specifically, there are two drive motors M1 for driving the wheels T, a braking motor M2, and a steering motor M3. These will be described in detail later.

[0027] The housing H is provided with an upper knuckle N1 and a lower knuckle N2 that support the housing H on the vehicle body Va. As shown in FIG. 2(b), the upper knuckle N1 and the lower knuckle N2 are formed to have dimensions that fit within the inner diameter of the wheel Ta. With this configuration, the unit U becomes extremely compact, and the design freedom of the support structure of the wheel T is greatly expanded. For example, the steering axis Xk formed between the upper knuckle N1 and the lower knuckle N2, i.e., the kingpin, is provided at a position that penetrates the housing H. Therefore, when the wheel T is viewed from the front, the intersection of the extension of the kingpin and the road surface coincides with the ground contact area of ​​the wheel T.

[0028] This reduces the scrub radius and eliminates unnecessary resistance during steering. This allows the steering motor M to be configured more compactly, resulting in a rational unit U. Furthermore, if the unit U is sized to fit within the inner diameter of the wheel Ta, a large loading space and the like of the vehicle body Va can be secured, making it easy to mount various auxiliary devices on the vehicle body Va, and increasing the effective utilization rate of the vehicle V, such as by expanding the living space for personnel.

[0029] (Drive unit) 3 shows a cross-sectional configuration of the drive unit 1 that performs the drive function in this embodiment. The drive unit 1 is equipped with two drive motors M1 at symmetrical positions around the axle Xt. It also includes a gear train that transmits rotational drive force from the drive motor M1 to the wheels. Since the two drive motors M1 and the gear trains have the same configuration, only one of the drive motors M1 will be explained.

[0030] The drive motor M1 is attached to the housing H from the outside of the vehicle V with its drive output shaft X1 parallel to the axle Xt. Therefore, when the drive motor M1 is to be attached to or detached from the housing H, the wheel Ta is removed.

[0031] Various types of motors M can be used as the drive motor M1. However, it is preferable to use one that is equipped with an encoder or the like and can calculate the rotation speed of the wheel T. The drive motor M1 is attached to the housing H with bolts or the like. A drive helical gear G1a with a small number of teeth is attached to the tip of the drive output shaft X1, and meshes with a large-diameter drive driven gear G1b that is provided to rotate integrally with the axle Xt. The use of helical gears improves the meshing ratio between the gears, resulting in smooth rotation transmission.

[0032] Furthermore, since the driving driven gear G1b is driven by the driving output shaft X1 at two symmetrical positions centered on the axle Xt, eccentricity and rattling of the driving driven gear G1b are suppressed, which also ensures smooth driving rotation.

[0033] The drive motor M1 is controlled by signals from a control unit 4 (not shown). As shown in Fig. 3, the ECU board Ea of the drive motor M1 is provided on the opposite side of the drive helical gear G1a from the drive motor M1. An IC chip and other components that obtain rotation information about the drive output shaft X1 are also mounted here.

[0034] (braking part) Fig. 4 shows a cross-sectional configuration of the braking unit 2 which exerts a braking function in this embodiment. The braking unit 2 is composed of a braking motor M2 and a clutch C. As shown in Fig. 4, the two are configured as a single assembly in a braking case 2a which is attached to a housing H. In the braking case 2a, the braking motor M2 and the clutch C are arranged in parallel, and the rotational drive of the braking motor M2 is transmitted to the clutch C via a spur gear.

[0035] The braking motor M2 is controlled by, for example, the control unit 4, and is driven to rotate when braking the wheel T. A small-diameter first spur gear G2a is provided on the braking output shaft X2, and the rotation of this gear is transmitted to a clutch gear G2c of the clutch C via a first intermediate gear G2b. The rotation of the clutch gear G2c is further transmitted to the clutch shaft Xc. A clutch pressure plate C1 is screwed onto the clutch shaft Xc. The clutch pressure plate C1 has a cylindrical portion C1b that screws onto the clutch shaft Xc, and a disk-shaped pressure portion C1a provided at the end of the cylindrical portion C1b.

[0036] The outer peripheral surface of the cylindrical portion C1b is surrounded by a cylindrical receiving portion 2a1 that protrudes from a part of the brake case 2a. At least one protruding guide 2ag is formed on the inner surface of the receiving portion 2a1 in parallel with the extension direction of the clutch shaft Xc, and a groove portion C1c that engages with the protruding guide 2ag to thrust-move the clutch pressure plate C1 is formed on the outer peripheral surface of the cylindrical portion C1b. In other words, the clutch shaft Xc is rotated by the brake motor M2, so that the clutch pressure plate C1 thrusts.

[0037] On the outer peripheral surface of the receiving portion 2a1 provided on the brake case 2a, for example, three first clutch plates C2 are arranged, which are non-rotatable with respect to the receiving portion 2a1 and can move in parallel along the protruding direction of the receiving portion 2a1. In addition, a second clutch plate C3 is interposed between these first clutch plates C2. The second clutch plate C3 is provided on the inner surface of the brake drum C4, which rotates coaxially with the clutch shaft Xc, so as to be non-rotatable relative to the brake drum C4 and to be movable along the rotation axis of the brake drum C4. The brake drum shaft Xc2 is connected to one end of the brake drum C4 by serration engagement, and a first brake gear G2d composed of a helical gear is provided on this brake drum shaft Xc2. On the other hand, a second brake gear G2e, with which the first brake gear G2d meshes, is provided on the outer surface of the axle Xt.

[0038] In other words, when the axle Xt rotates, the brake drum C4 rotates in response via the second brake gear G2e and the first brake gear G2d. In contrast, when the brake motor M2 is in a non-operating state, the clutch pressure plate C1 does not operate, and no frictional force is generated between the first clutch plate C2 and the second clutch plate C3. On the other hand, when the brake motor M2 is driven, the first clutch plate C2 is pressed against the second clutch plate C3, increasing the frictional force, and the axle Xt is braked via the brake drum C4.

[0039] (Steering section) 5 shows a cross-sectional configuration of the steering unit 3 which performs the steering function in this embodiment. The steering unit 3 includes a steering motor M3 and a gear train extending from the steering motor M3 to a steering shaft Xk provided in a housing H.

[0040] Specifically, a first steering gear G3a is provided at an end of a steering output shaft X3 of the steering motor M3, and meshes with a first steering intermediate gear G3b provided in the housing H. A first steering helical gear G3c having a small number of teeth is provided on the shaft of the first steering intermediate gear G3b. Furthermore, a rod-shaped second steering intermediate gear G3d meshes with the first steering helical gear G3c, and the other end of the second steering intermediate gear G3d meshes with a steering gear G3e attached to the exterior of the steering shaft Xk.

[0041] The steering motor M3 does not rotate and remains stationary when the vehicle V continues to travel in a straight line or turn. On the other hand, when transitioning to another steering state, the steering motor M3 rotates by a predetermined angle based on a control signal from the control unit 4. Therefore, it is preferable that the steering motor M3 is equipped with an encoder or the like so as to be able to detect the rotation angle.

[0042] When the steering gear G3e is driven, the steering second intermediate gear G3d tends to move away from the steering gear G3e due to the reaction force between the gears. Also, there may be a backlash between the gears from the beginning. In that case, when the steering rotation direction is reversed, the steering becomes inoperative, the steering operation becomes unstable, and the steering feel becomes worse. Furthermore, the wheel will vibrate in response to the input from the wheel by the amount of the backlash. To prevent this, it is advisable to provide a biasing portion 3a adjacent to the steering second intermediate gear G3d.

[0043] The need for such biasing of the gears is related to mounting the drive motor M1, the brake motor M2, etc. in the same direction relative to the housing H. Holding the position of the drive output shaft X1, etc. depends on the machining position of the bearing part provided in the wall of the housing H, etc. If there is a machining error, the gears will not necessarily mesh optimally. Therefore, a biasing part 3a is provided, configured to press the second steering intermediate gear G3d against the steering gear G3e.

[0044] Specifically, the bearing 3b that rotatably supports the end of the steering second intermediate gear G3d is spring-biased in a direction perpendicular to the axis of the steering second intermediate gear G3d and toward the steering gear G3e. For this purpose, a coil spring 3c having a predetermined spring constant may be provided in a part of the housing H. If the steering second intermediate gear G3d is a worm in this way, it is easy to ensure the distance between the meshing position with respect to the steering gear G3e and the spring-biased position, and the effect of maintaining the meshed state is improved.

[0045] By providing the biasing portion 3a as in this configuration, no rattle occurs during the drive transmission between the gear trains, allowing for smooth and quiet drive. In addition, as a result of suppressing rattle, the gears are kept in proper contact with each other, preventing problems such as uneven wear of the gears and reduced durability.

[0046] As shown in FIG. 2, in this embodiment, the output shafts of all the motors M, ie, the drive motor M1, the braking motor M2, and the steering motor M3, are parallel to each other and are provided parallel to the axle Xt.

[0047] If the extending directions of the rotation shafts of all the motors M are parallel, it is possible to rationally set the configuration of the mechanism connected to the output shaft of each motor M. For example, if the axial directions of each motor M are parallel, it is possible to install each auxiliary device in the space on the same side of the motor M.

[0048] In addition, various gear trains are often engaged with the motor M, and if the output shafts are parallel, it is easy to avoid interference between the gear trains attached to each of them. For example, since the various gears that engage with the output shaft of the motor M are often aligned along the direction of the output shaft, the mounting position of the gears can be adjusted along the axial direction. Therefore, with this configuration, the assembly and maintenance work of the unit U becomes efficient.

[0049] (Housing configuration) The housing H of this embodiment can be a box-shaped one-piece structure as shown in Fig. 6. Such a housing H can be formed by, for example, injection molding using aluminum, cutting out from a block material, or casting using iron.

[0050] This makes it possible to maintain high overall rigidity even if the thickness of the housing H is set thin. It also makes it easier to position and fix the motors M, making assembly more efficient. Also, covering many parts of the unit U improves the dustproof effect.

[0051] Although not shown in the drawings, the housing H can be constructed as a single unit, or can be constructed of a housing body having an outer peripheral wall, and a flat front cover and back cover perpendicular to the axle Xt to close the housing body. The front cover and back cover are fixed to the housing body using bolts or the like. With this configuration, the motors M, gears, and other components can be attached and detached from two directions along the axle Xt, improving workability.

[0052] (Functional variations of wheel motor units) By using the unit U having the above configuration, it is possible to configure a vehicle V with various variations, for example, as shown in Fig. 7. In other words, various types of units U can be applied as the front and rear wheels of a four-wheeled vehicle V.

[0053] For example, if both the front and rear wheels are configured with a unit U (A in FIG. 7) equipped with a drive motor M1, a braking motor M2, and a steering motor M3, the wheel T supported by the unit U can turn with a small radius, as well as travel diagonally and turn on the spot. In this case, for example, it can be used as a factory transport vehicle or mobility in a commercial facility.

[0054] Also, as shown in FIG. 7B, if the front wheels are provided with the three motors M and the rear wheels are provided with only a drive motor M1 and a braking motor M2, it becomes a general four-wheel drive vehicle.

[0055] As shown in FIG. 7C, if the rear wheels are not provided with a drive motor M1, but instead with a braking motor M2 and a steering motor M3, the vehicle can travel in the same manner as the vehicle V configured in paragraph

[0046] .

[0056] Furthermore, as shown in Fig. 7D, the rear wheels may be provided with only the braking motor M2. With this configuration, it is possible to obtain a vehicle V with a simple configuration, such as a factory transport vehicle.

[0057] Furthermore, a braking motor M2 and a steering motor M3 can be provided for the front wheels, and all of the motors M can be provided for the rear wheels (Figure 7, center), or a drive motor M1 and a braking motor M2 can be provided for the rear wheels (Figure 7, center), resulting in a general rear-wheel drive vehicle.

[0058] In addition, as shown in Fig. 7G, a three-wheeled vehicle V can be configured. With this configuration, an extremely small and maneuverable vehicle V can be configured. Since the three-wheeled vehicle V has small body dimensions, by using the unit U of this embodiment, the effect of expanding the vehicle mounting space is remarkable.

[0059] Second Embodiment The unit U shown in Figure 8 does not include the brake motor M2. The motors visible on the left and right are the drive motors M1, and the steering motor M3 is in a different position from this cross section. In this example, a drum brake B is provided in the center of the drive driven gear G1b provided on one side of the axle Xt.

[0060] A recess Ba is formed on the rear side of the driving driven gear G1b, and its inner peripheral surface serves as the abutment surface Bf of the brake shoe Bb. The brake shoe Bb can be driven in various ways, such as by the rider's operation or by a braking mechanism (not shown). With this configuration, the meshing positions of the driving helical gear G1a and the driving driven gear G1b and the abutment surface Bf are in a substantially front-rear positional relationship. Therefore, the length of the driving driven gear G1b along the extension direction of the axle Xt is reduced, resulting in space saving.

[0061] In addition, in this configuration, the ECU board Ea of the drive motor M1 is provided on the outside of the vehicle V relative to the drive motor M1. This shortens the distance from the drive motor M1 to the bus bar Eb, making it easier to connect the wiring. Furthermore, by providing the rotation sensor and the like on the ECU board Ea, twisting of the drive output shaft X1 is less likely to occur compared to the case where the rotation sensor is located further beyond the drive helical gear G1a. This improves the accuracy of identifying the rotation phase of the drive output shaft X1.

[0062] Third embodiment When the unit U of the present invention is used in a four-wheeled vehicle V, it is not necessary to arrange units U of the same configuration for the left and right wheels T. For example, in the example shown in Fig. 9, the steering motor M3 may be provided only in the left unit UL arranged on the left wheel TL, and the steering link L may be provided across the left housing HL and the right housing HR.

[0063] In this configuration, the driving force of the steering motor M3 provided on one of the left wheels TL must be transmitted to the other right wheel TR, and factors such as a relatively strong driving force of the steering motor M3 or low steering resistance of the wheel T against the road surface are required. However, if these conditions are met, the total number of steering motors M3 can be reduced, and the device configuration related to the entire vehicle V can be further streamlined. [Industrial Applicability]

[0064] The wheel motor unit of the present invention can be widely used in vehicles in which driving and braking are performed for each individual wheel. [Explanation of symbols]

[0065] 3a Biasing part H Housing HR Right Housing HL Left housing L Link Medium motor T-wheel Ta Wheel TR right wheel TL Left Wheel U Wheel motor unit V Vehicle Va Body X output shaft xt axle

Claims

1. a housing to which an axle supporting a wheel of a vehicle is attached and which is supported by a vehicle body; a plurality of motors attached to the housing; Each of the motors performs either a steering function for changing the attitude of the axle, a driving function for rotating the axle, or a braking function for restricting the rotation of the axle, A wheel motor unit in which the extending directions of the rotation shafts of the motors are parallel to each other.

2. The wheel motor unit according to claim 1 , wherein the housing is configured so that the entire housing fits within an inner diameter of the wheel of the vehicle.

3. 2. The wheel motor unit according to claim 1, wherein a gear train for transmitting the driving rotation of the output shaft of the motor is provided in the housing, and a biasing portion is provided on one of the meshing gears for pressing against the other gear.

4. A wheel motor unit as described in any one of claims 1 to 3, wherein a link is provided between a left housing provided on a left wheel as the housing and a right housing provided on a right wheel as the housing, and the motor provided in the left housing or the right housing and performing the steering function, the driving function or the braking function is configured to perform the steering function, the driving function or the braking function for the other wheel.

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