Vehicular power unit

Abstract

To provide a vehicular power unit having a mechanism which prevents or suppresses grease leakage from the inside, corrosion and so forth while avoiding or reducing an increase in torque, in a configuration having measures against the entry of a foreign object from the outside.SOLUTION: A vehicular power unit comprises: a wheel bearing having a fixed ring, a rolling element, and a rotary ring supported via the rolling element in a manner rotatable with respect to the fixed ring; a first electrical component fitted to the fixed ring; and a second electrical component fitted to the rotary ring. The vehicular power unit further comprises: a fixed-side case including the first electrical component; and a rotary-side case including the second electrical component. A seal member is provided between the fixed-side case and the rotary-side case. A gap structure having a minute gap in the radial direction is provided between the fixed ring and the rotary ring.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a vehicle power unit for a vehicle, which includes a fixed ring having a fixed side case, a rotating ring having a rotating side case, and rolling elements interposed between the fixed ring and the rotating ring. [Background technology]

[0002] Bearing devices are used as components for supporting various rotating devices and the rotating shaft of wheels in general industrial machines. A wheel bearing for supporting a wheel includes a fixed ring, a rolling element, and a rotating ring supported rotatably relative to the fixed ring via the rolling element. One of the fixed ring and the rotating ring is a so-called inner ring, and the other is a so-called outer ring. That is, in a vehicle, for example, one of the inner ring and the outer ring is fixed to a vehicle body part (such as a suspension frame part) on the vehicle body side (fixed side) such as a knuckle, and the other rotates relative to the one. As shown in FIG. 1, for example, in a hub bearing BR, the periphery of the rolling element RE (also called a bearing part) between the inner ring IR and the outer ring OR is filled with a lubricant such as grease GR in terms of lubrication during the above-mentioned rotation around the rotation axis C.

[0003] Furthermore, recent vehicles are becoming increasingly electrified, increasing the demand for in-vehicle motors, etc. As part of this trend toward electrification, in-wheel motors, which incorporate motors inside the wheels, are being developed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 11,078,954 Summary of the Invention [Problem to be solved by the invention]

[0005] A typical wheel bearing is provided with a seal member SL as shown in FIG. 1 to prevent grease from leaking out from inside the wheel bearing and foreign matter such as water and dust from entering from the outside. However, the drag resistance of this seal member (hereinafter simply referred to as a seal) increases the torque (hereinafter simply referred to as torque increase). Here, if a structure is adopted in which the seal shown in FIG. 1 is not used in the gap, such as the control gap GC for preventing brinelling in Patent Document 1 as shown in FIG. 2, the above-mentioned drag resistance does not occur, but it is difficult to prevent foreign matter such as water from entering the wheel bearing and grease from leaking out from the hub bearing in a normal usage environment of the hub bearing. In addition, in the structure of Patent Document 1, since the control gap GC is an axial gap, the centrifugal force during rotation makes it easier for grease to scatter to the outside. Note that the structure of Patent Document 1 has a flange on the inner ring, which may increase costs due to increased material and processing parts.

[0006] Even if a structure is provided to prevent the intrusion of water and other foreign matter, without a mechanism to prevent or suppress grease leakage from inside the wheel bearing, poor lubrication around the rolling elements will lead to premature wear of the wheel bearing. Wheel bearings with cases are more difficult to replace than regular wheel bearings, which poses an issue regarding maintainability.

[0007] Here, when the wheel support bearing includes electrical components such as a sensor for detecting rotation or the like and a motor, a unit structure is known in which a vehicle power unit 100 includes a fixed case 7 and a rotating case 6, and a seal member 8 is provided between the fixed case 7 and the rotating case 6 for the purpose of preventing foreign matter such as water and dust from entering from the outside, as shown in FIG. 3. This structure can prevent foreign matter such as water from entering the inside of the wheel support bearing. Here, in a structure in which measures are taken to prevent foreign matter from entering from the outside, if a seal member is further provided around the bearing portion as in a normal wheel support bearing to prevent or suppress the outflow of grease from inside the wheel support bearing, drag resistance increases, resulting in increased torque.

[0008] In addition, if a large amount of grease is scattered from inside the wheel bearing, in addition to the poor lubrication mentioned above, if the unit in Figure 3 includes electrical parts such as the motor rotor 4 and stator 5, or sensors for detecting rotation, etc., if grease adheres to the wiring, etc., it may corrode the resin on the surface of the wiring, causing peeling of the parts and resin, and electric leakage, etc. (hereinafter referred to as corrosion, etc. [of electrical parts, etc.]).

[0009] Therefore, in order to solve the problems of the conventional technology described above, the object of the present invention is to provide a vehicle power unit having a mechanism for preventing or suppressing the occurrence of grease leakage, corrosion, etc. from inside the wheel bearing while avoiding or reducing torque increase in a configuration that has measures in place to prevent the intrusion of foreign matter from the outside. [Means for solving the problem]

[0010] The vehicle power unit according to the present invention comprises: A wheel bearing including a fixed ring, a rolling element, and a rotating ring supported rotatably relative to the fixed ring via the rolling element; A first electrical component attached to the fixed ring; A vehicle power unit including a second electrical component attached to the rotating wheel, a stationary case including the first electrical component; a rotating case including the second electrical component, A seal member is provided between the stationary case and the rotating case, Between the fixed ring and the rotating ring, there is a gap structure having a minute gap in the radial direction.

[0011] According to this configuration, the vehicle power unit of the present invention has a configuration in which measures are taken to prevent the intrusion of foreign matter from the outside by the fixed case, the rotating case, and the seal member, and in addition, the gap structure having a minute gap in the radial direction exists between the fixed ring and the rotating ring, so that grease leakage from inside the wheel bearing is suppressed. Also, the control gap GC of the structure of Patent Document 1 is an axial gap, and while grease and the like tend to actively flow out to the outside due to centrifugal force, this is less susceptible to the influence of this centrifugal force. Therefore, it is possible to prevent or suppress the occurrence of the above-mentioned external leakage and corrosion while avoiding or reducing torque increase. In other words, it is possible to reduce the occurrence of grease leakage and corrosion from the inside (the effects of prevention, avoidance, inhibition, inhibition, reduction, etc. are collectively referred to as reduction, etc.).

[0012] The gap structure may have a minute gap in the axial direction following the minute gap in the radial direction. Therefore, as in the above example, there is a minute gap in the axial direction following the minute gap in the radial direction between the fixed ring and the rotating ring, so that the above-mentioned leakage to the outside, etc. is reduced. In this configuration, the shape of the gap is a stepped structure and has a more complex shape than in the above example, so that the occurrence of the above-mentioned leakage to the outside and corrosion, etc. is further reduced.

[0013] The gap structure may have the minute gap between the fixed ring and the rotating ring, in which the first surface of the fixed ring and the second surface of the rotating ring are forged. Therefore, the occurrence of the above-mentioned external leakage and corrosion can be reduced due to the relationship between the uneven shape of the forged surface and the viscosity of the grease, etc. Note that the uneven shape may be formed by processing, but it is also possible to eliminate the need for processing by leaving the forged surface as it is, thereby reducing costs.

[0014] A grease reservoir may be present between the rolling element and the minute gap, and this grease reservoir can store grease and the like, thereby hindering the flow of grease and the like, thereby reducing the occurrence of leakage to the outside and corrosion, etc.

[0015] The gap structure may have a minute gap having a tapered structure in which the interval L between the fixed ring and the rotating ring narrows toward the rolling element. Thus, the surface tension and capillary phenomenon in the tapered structure can draw grease or the like inward, thereby reducing the occurrence of the above-mentioned external leakage and corrosion.

[0016] The minute gap between the fixed ring and the rotating ring may have a distance L determined by the following formula (1). Dimensional tolerance + geometric tolerance + reduction in the small gap when the assumed load is applied < L ≦ 1.5 (1) This prevents the fixed ring from coming into contact with the rotating ring, and reduces the occurrence of the above-mentioned leakage to the outside and corrosion due to the viscosity of the grease, etc. Effect of the Invention

[0017] The vehicle power unit of the present invention is configured in such a way that measures are taken to prevent the intrusion of foreign matter from the outside, and can prevent or suppress the occurrence of grease leakage, corrosion, etc. from the inside while avoiding or reducing torque increase. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a vertical cross-sectional view showing an example of a conventional hub bearing. [Diagram 2] FIG. 11 is a vertical cross-sectional view showing another example of a conventional hub bearing. [Diagram 3] 1 is a longitudinal sectional view of a vehicle power unit including a wheel support bearing having a clearance structure according to an embodiment of the present invention. [Figure 4] 4 is a vertical cross-sectional view showing another example of a vehicle power unit including the wheel support bearing. FIG. [Diagram 5] 4 is a vertical cross-sectional view showing another example of a vehicle power unit including the wheel support bearing. FIG. [Figure 6] 4 is a partial vertical cross-sectional view showing an upper half of a vehicle power unit equipped with another example of a clearance structure according to the embodiment. FIG. [Figure 7]13 is a partial vertical cross-sectional view showing the upper half of a vehicle power unit equipped with yet another example of a clearance structure. FIG. [Figure 8] 13 is a partial vertical cross-sectional view showing the upper half of a vehicle power unit equipped with yet another example of a clearance structure. FIG. [Figure 9] 13 is a partial vertical cross-sectional view showing the upper half of a vehicle power unit equipped with yet another example of a clearance structure. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] A vehicle power unit according to an embodiment of the present invention will be described with reference to Figs. 3 to 9. As shown in Fig. 3, the vehicle power unit 100 is equipped with a wheel bearing unit to which a wheel is attached by, for example, bolts 13, and which includes an outer ring 3, which is a fixed ring in this embodiment, a double row of rolling elements 12, and an inner ring 2, which is a rotating ring in this embodiment. The inner ring 2 is crimped to the hub ring 1 and is supported rotatably relative to the outer ring 3 via the rolling elements 12. Therefore, the hub ring 1 is a rotating ring that is integrated with the inner ring 2 and rotates together with it, and therefore, in this embodiment, it may be treated as being included in the narrowly defined inner ring 2, which is a rotating ring. The vehicle power unit 100 also includes a motor unit that serves as both an electric motor and a generator, and is composed of a motor rotor 4 (also simply referred to as a rotor) and a motor stator 5 (also simply referred to as a stator), etc.

[0020] The motor unit generates electricity through regenerative braking, and can rotate and drive the wheels by receiving power. In this embodiment, the motor unit is an outer rotor type, and can constitute, for example, a surface permanent magnet motor, that is, an SPM (Surface Permanent Magnet) synchronous motor (or SPMSM (Surface Permanent Magnet Synchronous Motor)), an IPM (Interior Permanent Magnet) synchronous motor (or IPMSM (Interior Permanent Magnet Synchronous Motor)), or a switched reluctance motor. The outer ring 3 includes a motor stator 5 that is a first electrical component that constitutes the electrical unit, and the inner ring 2 includes a motor rotor 4 that is a second electrical component that constitutes the electrical unit. In addition to the above, the motor unit may also include electrical components such as sensors for detecting rotation.

[0021] In the bearing space between the outer ring 3 and the inner ring 2, which in this embodiment is the bearing portion around the rolling elements 12 between the inner ring 2 and the outer ring 3, a lubricant such as grease GR is filled in order to provide lubrication during rotation around the rotation axis C. The outer peripheral surface on the inboard side of the outer ring 3 is fixed by bolts 11 to a vehicle body part 10 (suspension frame part, etc.) such as a knuckle on the vehicle body side (fixed side), which is a suspension frame part. In this specification, when the vehicle power unit 100 is mounted on a vehicle, the side that is closer to the outside in the vehicle width direction of the vehicle is called the outboard side, and the side that is closer to the center in the vehicle width direction of the vehicle is called the inboard side.

[0022] In this embodiment, a seal member 8 is present between the fixed side case 7 and the rotating side case 6. Specifically, the seal member 8 is interposed between the inner peripheral surface on the inboard side of the rotating side case 6 and the outer peripheral surface on the inboard side of the fixed side case 7. The presence of this seal member 8 makes it possible to prevent foreign matter such as water and dust from entering from the outside when the vehicle power unit 100 is mounted to a wheel.

[0023] The rotor 4 in Fig. 3 includes a plurality of permanent magnets provided on the inner circumferential surface of the rotating case 6. For example, a plurality of recesses are formed on the inner circumferential surface of the rotating case 6 at regular intervals in the circumferential direction, and a permanent magnet 14 is fitted into each recess and fixed by adhesion or the like. The rotating case 6 is made of, for example, a soft magnetic material and has a cylindrical shape concentric with the inner ring 2. The rotating case 6 may be manufactured as an integrated metal part by cutting or casting, or may be manufactured from a plurality of divided structures and then these divided structures may be fixed by, for example, welding, adhesion, or the like.

[0024] As described above, in the structure of this embodiment shown in FIG. 3, the wheel bearing section of the vehicle power unit 100 is structured to be housed in a sealed housing (fixed side case 7, rotating side case 6) together with the motor section and the seal member 8. Therefore, the wheel bearing section of the vehicle power unit 100 does not need to be prevented from the outside from entering foreign matter such as water. However, it must be noted that it is necessary to prevent grease from leaking out from inside the wheel bearing in terms of poor lubrication inside the wheel bearing. If a seal member is provided around the bearing section in addition to the seal member 8, as in a normal wheel bearing, in order to prevent or suppress the leakage of grease from inside the wheel bearing, an increase in torque due to drag resistance may occur. Therefore, in order to avoid the increase in torque, it is necessary to suppress drag torque as much as possible at least in a mechanism that prevents or suppresses grease leakage from inside the wheel bearing.

[0025] Therefore, in the wheel bearing of this embodiment, a clearance structure 200 (a dashed rectangular portion in the figure) having a minute clearance (i.e., a space extending in the axial direction) 210 in the radial direction is present between the outer ring 3 as the fixed ring and the inner ring 2 as the rotating ring, which is based on the formation of a radial clearance in order to suppress the drag torque. The clearance structure 200 is provided on at least one of the inboard side and the outboard side of the row of rolling elements 12, but in this embodiment, it is provided on both sides. In Figs. 3 to 9, the structure of the minute clearances 210 to 250, which are characteristic of this embodiment described below, is shown only in the inboard side clearance structure 200, and may not be shown in the outboard side clearance structure 200. In the structure of Patent Document 1, grease and the like are likely to actively flow out due to centrifugal force, but in the structure of this embodiment, the effect of this centrifugal force is reduced, and the above-mentioned outflow to the outside is reduced. The distance L between the outer ring 3 and the inner ring 2 in the minute gap 210 is a dimension that can reduce the outflow of the grease GR due to the relationship between the surface parts of the outer ring 3 and the inner ring 2 and the viscosity of the grease GR, and the above-mentioned outflow to the outside can be reduced. Also, when electrical parts such as the rotor 4 and stator 5 of the motor and sensors for detecting rotation are included, if grease adheres to the wiring, the resin on the wiring surface can corrode, causing peeling of the parts and resin, and electric leakage. However, the above-mentioned configuration can reduce the occurrence of such corrosion. Furthermore, the above-mentioned configuration can reduce the manufacturing costs of the wheel bearing by eliminating the seal. (In the following, when referring to the effect of reducing outflow to the outside, the effect of reducing the occurrence of corrosion and the like and reducing manufacturing costs that are achieved at the same time are also included.)

[0026] 4 and 5 show an example of a vehicle power unit 100 different from the example of Fig. 3, which is a wheel bearing type in which the inner ring 2 is fixed to an inner ring shaft 1A fixed to a vehicle body part (such as a suspension frame part) on the vehicle body side (fixed side) such as a knuckle, and the outer ring 3 rotates. In the example of Fig. 4 and 5, the clearance structure 200 having a minute gap in the radial direction is provided between the inner ring 2 as the fixed ring and the outer ring 3 as the rotating ring, which has the effect of reducing the outflow to the outside.

[0027] In the clearance structure 200 of the vehicle power unit 100 in FIG. 6, not only is there a minute gap 222 in the radial direction between the outer ring 3 as a fixed ring and the inner ring 2 as a rotating ring like the minute gap 210 shown in FIGS. 3 to 5, but there is also one or more minute gaps 220 having an axial minute gap (i.e., a space extending in the radial direction) 221 continuing to the radial minute gap 222 toward the direction of the rolling element 12 (there is only one minute gap 220 in this embodiment). In the example of FIG. 6, the minute gap 220 has an axial minute gap 221 between the outer ring 3 as a fixed ring and the inner ring 2 as a rotating ring as in Patent Document 1, but in this example, as in the example of FIG. 3, there is the clearance structure 200 having the minute gap 222 in the radial direction continuing to the minute gap 221 in the direction opposite to the direction toward the rolling element 12, i.e., in the direction of the outflow outlet 243 which is the opening of the inboard minute gap 220, and the outflow to the outside is reduced, etc. In this structure, the shape of the gap 220 is stepped and has a more complex shape than in the example of FIG. 3, so that the leakage to the outside is further reduced.

[0028] In the clearance structure 200 of the vehicle power unit 100 in FIG. 7, a first surface 233 of the inner peripheral surface of the outer ring 3 and a second surface 232 of the outer peripheral surface of the inner ring 2 between the outer ring 3 and the inner ring 2 have a minute gap 230 in which the forged surface remains. The forged surface refers to the surface portion of the forged product (in this embodiment, the outer ring 3, the inner ring 2, etc.) after forging, and here, it is assumed that the surface has an uneven state after hot forging. In this structure in which the portion forming the minute gap 230 remains as the forged surface, the outflow of the grease GR can be reduced due to the relationship between the surface roughness of the uneven shape of the forged surface and the viscosity of the grease GR. By leaving the forged surface as it is, no processing is required and the uneven shape is utilized to reduce costs, but the uneven shape may be formed by processing.

[0029] In the gap structure 200 of the vehicle power unit 100 in FIG. 8, in addition to the minute gap 240, one or more grease reservoirs 242 are provided between the rolling element 12 and the minute gap 240 (there is one grease reservoir 242 in this embodiment). In detail, the grease reservoir 242 is a space having a cross-sectional area larger than that of the minute gap 240 so as to be capable of storing a small amount of grease GR, and exists between an outlet 243, which is an opening on the inboard side (and / or outboard side) of the minute gap 240, and a grease retaining portion 241 between the outer ring 3 and the rolling element 12 and between the inner ring 2 and the rolling element 12, where the grease GR is retained by viscosity, surface tension, or the like. The grease reservoir 242 temporarily retains and stores the grease GR, thereby hindering the flow of the grease GR and reducing the outflow to the outside. The grease reservoir 242 can be provided at any position between the grease retaining portion 241 and the outflow outlet 243. Furthermore, in a location where the grease reservoir 242 can be formed by forging, forming the grease reservoir 242 by forging eliminates the need for forming by machining, but the grease reservoir 242 may be formed by machining.

[0030] In the gap structure 200 of the vehicle power unit 100 of FIG. 9, the minute gap 250 is tapered. By forming the minute gap 250 into a tapered structure, a force that draws the grease GR in the inboard side gap structure 200 acts in the inboard side direction, that is, in the inboard side direction, due to surface tension and capillary phenomenon in the taper, and a force that draws the grease GR in the inboard side direction acts in the outboard side gap structure 200, so that the outflow of the grease GR is reduced. In detail, the gap structure 200 has the minute gap 250 having a tapered structure in which the interval L between the outer ring 3 and the inner ring 2 narrows from the outflow outlet 243 toward the rolling element 12. Therefore, as described above, the grease GR can be drawn in the inward direction, and the outflow of the grease GR to the outside can be reduced. In addition, if a taper is provided on the outer periphery 252 of the rotating ring having a smaller diameter (the inner ring 2 side), the grease GR can be further drawn inwardly where the rotational diameter becomes larger on the outer periphery surface of the outer periphery 252 due to the centrifugal force during rotation. However, the taper may be formed on the inner periphery 253 of the fixed ring side (the outer ring 3 side), or may be formed on both the outer periphery 252 and the inner periphery 253.

[0031] The distance L (mm) between the outer ring 3 and the inner ring 2 in the minute gaps 210 to 250 is set according to the following formula (1), with the upper limit being 1.5 mm. Dimensional tolerance + geometric tolerance + reduction in the above minute gap when the assumed load is applied <L≦1.5···(1) Here, the "dimensional tolerance" refers to the tolerance of the dimensions of the portions where the minute gaps 210 to 250 are formed, the "geometric tolerance" refers to the tolerance of the geometric characteristics specified for the portions where the minute gaps 210 to 250 are formed, and the "reduction amount of the minute gap when an assumed load is applied" refers to the consideration of the reduction amount of the gap, assuming that the rotating wheel tilts due to the load applied when the vehicle turns, for example. The lower limit in the above formula is set so that the non-rotating side (the outer ring 3 side of the fixed wheel) and the rotating side (the inner ring 2 side of the rotating wheel) do not come into contact even when a load is applied. The upper limit is set as narrow as possible because the narrower the gap L is set, the greater the effect of suppressing and reducing grease outflow. On the other hand, there are other ways to deal with this, such as the above-mentioned case where the forged surface is left to suppress outflow and reduce costs, so in order to provide that range, the upper limit is set to 1.5 mm, taking into consideration the relationship with the viscosity of the grease, etc.

[0032] The above describes the form for carrying out the present invention based on the embodiment, but the embodiment disclosed this time is illustrative in all respects and is not restrictive. The scope of the present invention is indicated by the claims, not by the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims. For example, the wheel bearing part may have an outer ring 3 which is a rotating ring and an inner ring 2 which is a fixed ring. In addition, although the minute gaps 210 to 250 are applied to the inboard side clearance structure 200 in the above, the minute gaps 210 to 250 may be applied to the outboard side clearance structure 200. [Explanation of symbols]

[0033] 1...hub wheel, 2...inner wheel (rotating wheel), 3...outer wheel (fixed wheel), 4...motor rotor, 5...motor stator, 6...rotating case, 7...fixed case, 8...sealing member joint, 9, 11, 13...bolt wheel, 10...body part, 12...rolling body, 100...vehicle power unit, 200...clearance structure, 210, 220, 230, 240, 250...micro gap, C...(rotating) shaft

Claims

1. A wheel bearing including a fixed ring, a rolling element, and a rotating ring supported rotatably relative to the fixed ring via the rolling element; A first electrical component attached to the fixed ring; A second electrical component attached to the rotating wheel, a stationary case including the first electrical component; a rotating case including the second electrical component, A seal member is provided between the stationary case and the rotating case, A gap structure having a minute gap in the radial direction is present between the fixed ring and the rotating ring. Vehicle power unit.

2. 2. The vehicle power unit according to claim 1, The gap structure has an axial microgap following the radial microgap, Vehicle power unit.

3. 2. The vehicle power unit according to claim 1, The gap structure has the minute gap between the fixed ring and the rotating ring, the first surface of the fixed ring and the second surface of the rotating ring being forged surfaces, Vehicle power unit.

4. 2. The vehicle power unit according to claim 1, A grease reservoir exists between the rolling element and the minute gap. Vehicle power unit.

5. 2. The vehicle power unit according to claim 1, The gap structure has a minute gap having a tapered structure in which the distance L between the fixed ring and the rotating ring narrows toward the rolling element, Vehicle power unit.

6. The vehicle power unit according to any one of claims 1 to 5, The distance L between the fixed wheel and the rotating wheel in the minute gap is determined by the following formula (1): Vehicle power unit. Dimensional tolerance + geometric tolerance + reduction in the minute gap when the assumed load is applied < L ≦ 1.5 ... (1)

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