Power supply unit and bearing unit

Abstract

To provide a power supply unit and a bearing unit that can ensure a stable power supply state. [Solution] The current-carrying unit 1 is configured to have a conductive annular case body 2 having a gap that opens radially inward, a conductive current-carrying member 3 provided in the gap and protruding radially inward from the case body 2, and a current-carrying auxiliary member 4 provided between the case body 2 and the current-carrying member 3 to assist in current flow between the case body 2 and the current-carrying member 3. The bearing unit A is configured to have a current-carrying unit 1, an outer ring 14, an inner ring 15 arranged on the inner diameter side of the outer ring 14, rolling elements 16 provided between the outer ring 14 and the inner ring 15, and a cage 17 that holds the rolling elements 16 at predetermined intervals in the circumferential direction, and a bearing 7 arranged so that the outer ring 14 abuts against the current-carrying unit 1.

Description

Technical Field

[0001] The present invention relates to an energization unit and a bearing unit in which the energization unit and a bearing are integrated.

Background Art

[0002] As a bearing that supports a rotating shaft such as a motor shaft of an automotive e-axle, a rolling bearing, particularly a ball bearing, is generally used. In recent years, in order to efficiently operate a motor, inverter control is generally adopted. Particularly in the case of an in-vehicle motor, miniaturization has been achieved from the viewpoint of mounting on a vehicle, and in order to use the miniaturized motor more efficiently, finer control is being performed.

[0003] It has been found that shaft current and shaft voltage occur in this rotating shaft. When this current passes through the inside of the bearing, electric corrosion may occur in the raceway ring and rolling elements made of metal. Therefore, for example, in Patent Document 1 below, a sliding contact brush assembly 25 is provided near a countershaft 3c to which the rotation of a motor shaft 1b is transmitted, and a brush contact 5a protruding from a brush holder 5c of the sliding contact brush assembly 25 is brought into contact with a shaft end portion 3c' of the countershaft 3c to release electricity to a housing 3a, so that current does not pass through a ball bearing 13 (see FIG. 2 of Patent Document 1, etc.).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The configuration shown in Patent Document 1 is configured such that the brush contact 5a contacts a predetermined position on the shaft end 3c'. However, due to tilting of the sliding brush assembly 25 (brush contact 5a) caused by mounting errors, the contact state between the shaft end 3c' and the brush contact 5a may become unstable, making it impossible to ensure a stable current supply.

[0006] Therefore, the object of the present invention is to provide a power supply unit and a bearing unit that can ensure a stable power supply state. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides: A conductive annular case body portion having a gap that opens radially inward, A conductive current-carrying member is provided within the gap and protrudes radially inward from the case body, A power supply assisting member is provided between the case body and the power supply member to assist in the conduction of power between the case body and the power supply member, A power supply unit having the following was constructed (first configuration).

[0008] In this way, by assisting the conduction between the case body and the conduction member with the conduction assisting member, it is possible to prevent a gap from forming between the case body and the conduction member, which would reduce the conduction state, and to ensure a stable conduction state.

[0009] In the first configuration, the current-carrying auxiliary member can be configured as a biasing member provided adjacent to the current-carrying member in the axial direction and biasing the current-carrying member toward the case body from the axial direction (second configuration), as a conductive elastic member that biases the current-carrying member radially inward (third configuration), or as a conductive conductor that connects the case body and the current-carrying member (fourth configuration). In this way, a radial or axial current-carrying path is secured between the case body and the current-carrying member, making the current-carrying state more stable.

[0010] In the first to fourth configurations, a fifth configuration can be provided in which a bent portion is formed on at least one of a pair of axially opposing wall portions of the case body, which bends inward toward the inside of the gap as it moves from the outer diameter side toward the inner diameter side. In this way, when the conductive member is projected radially inward, the conductive member can be brought into contact with the bent portion, thereby making the current flow between the case body and the conductive member more stable.

[0011] In configurations 1 through 5, a configuration (sixth configuration) can be adopted in which multiple current-carrying members are provided in the circumferential direction. In this configuration, even if the current-carrying performance of some of the current-carrying members is impaired, it can be compensated for by the other current-carrying members, thereby ensuring stable current-carrying performance.

[0012] In the first to sixth configurations, the case body can be configured to have an annular outer ring portion having a flange extending in one axial direction on its outer edge, and a retainer that fits axially into the outer ring portion and has a flange extending in the opposite direction to the aforementioned axial direction on its outer edge (seventh configuration). In this way, conductive members and elastic members can be easily housed in the gap of the case body.

[0013] In configurations 1 through 7, the conductive member can be made of a conductive material formed from metal, carbon, or a resin, rubber, ceramics, or a composite thereof, with a volume resistivity of 10 Ω·cm or less (configuration 8). In this way, the conductive function of the conductive unit can be ensured with a simple configuration.

[0014] In the first through eighth components, A configuration (9th configuration) can be provided in which an annular elastic member is arranged in an outer groove formed on the outer surface of the current-carrying member and biases the current-carrying member radially inward.

[0015] The energizing unit according to the first to ninth configurations can be applied to a bearing unit having the energizing unit, an outer ring, an inner ring disposed on the inner diameter side of the outer ring, rolling elements provided between the outer ring and the inner ring, and a cage that holds the rolling elements at predetermined intervals in the circumferential direction, wherein the outer ring is disposed in contact with the energizing unit (tenth configuration). [Effects of the Invention]

[0016] In the current supply unit of the present invention, a current supply assisting member is provided between the case body and the current supply member that protrudes radially inward from the case body, thereby preventing a gap from forming between the case body and the current supply member and reducing the current supply state, and ensuring a stable current supply state. [Brief explanation of the drawing]

[0017] [Figure 1] Cross-sectional view showing a first example of the current supply unit according to the present invention. [Figure 2] Cross-sectional view of the main part of the power supply unit shown in Figure 1. [Figure 3] Cross-sectional view along line III-III in Figure 1 [Figure 4] Cross-sectional view along line IV-IV in Figure 3 [Figure 5] Cross-sectional view along the VV line in Figure 1 [Figure 6] Cross-sectional view taken along line VI-VI in FIG. 5 Cross-sectional view [Figure 7] Cross-sectional view showing the free state of the biasing member (plate spring) of the energization unit shown in FIG. 1 [Figure 8] Perspective view showing a push nut as a biasing member [Figure 9] Perspective view showing a wave washer as a biasing member [Figure 10] Cross-sectional view of the main part of the second example of the energization unit according to the present invention [Figure 11] Cross-sectional view of the main part of the third example of the energization unit according to the present invention [Figure 12] Cross-sectional view of the main part of the fourth example of the energization unit according to the present invention [Figure 13] Cross-sectional view of a bearing unit to which the energization unit shown in FIG. 1 is applied

Mode for Carrying Out the Invention

[0018] A first example of the energization unit 1 according to the present invention will be described based on the drawings. As shown in FIGS. 1 to 7, this energization unit 1 mainly includes a case main body portion 2, an energization member 3, and an energization auxiliary member 4. This energization unit 1 is provided between the motor shaft 5 and the housing 6 so as to be adjacent to a bearing 7 that supports the motor shaft 5 between the motor shaft 5 such as an e-axle and the housing 6. The housing 6 is electrically grounded.

[0019] From the viewpoint of the electric corrosion prevention effect, as shown in FIG. 1, it is preferable to provide the energization unit 1 and the bearing 7 in contact with each other in the axial direction, but a configuration in which a gap is provided between the two is also acceptable. Hereinafter, the direction along the axis of the motor shaft 5 is referred to as the axial direction, the direction perpendicular to the axis is referred to as the radial direction, and the direction along the circumference that makes one round around the axis is referred to as the circumferential direction.

[0020] The case body portion 2 is a conductive, annular member that is fitted into the inner diameter surface of the housing 6. As shown in Figure 2, the case body portion 2 consists of an annular outer ring portion 8 having a flange extending in one axial direction on its outer circumference, and a retainer 9 having a flange extending in the opposite direction to the aforementioned axial direction on its outer circumference. The outer ring portion 8 and the retainer 9 are integrated by press-fitting the flange formed on the retainer 9 into the flange formed on the outer ring portion 8.

[0021] Both the outer ring portion 8 and the retainer 9 are made of steel. Between the fitted outer ring portion 8 and the retainer 9, a gap is formed that opens toward the inner diameter, capable of accommodating the energizing member 3 and the energizing auxiliary member 4. The outer ring portion 8, which is one of a pair of axially opposed wall portions that constitute this gap, has a bent portion 10 formed thereon that bends toward the inside of the gap as it moves from the outer diameter side toward the inner diameter side. As shown in Figure 4, the retainer 9 has a plurality of bent portions 11 (four in this embodiment) that extend from its inner edge in the other axial direction (the same direction as the flange formed on the retainer 9) at predetermined angular intervals (every 90 degrees in this embodiment).

[0022] The conductive member 3 is a conductive member that extends circumferentially, protruding radially inward from the case body 2 and slidingly contacting the motor shaft 5 supported by the bearing 7. As shown in Figure 2, both axial end faces of the conductive member 3 are parallel to each other and inclined with respect to the axial direction (inclination angle: 1 to 5 degrees, preferably 1.5 to 2.5 degrees). The inclination angle of these inclined surfaces is approximately the same as the inclination angle of the bent portion 10 formed on the outer ring portion 8, and one axial end face of the conductive member 3 and the inner surface of the bent portion 10 of the outer ring portion 8 are in surface contact.

[0023] As shown in Figure 3, the inner circumferential surface of the conductive member 3 that contacts the motor shaft 5 is formed in an arc shape when viewed axially. The radius of curvature of this inner circumferential surface is approximately the same as the radius of curvature of the outer circumferential surface of the motor shaft 5, and the inner circumferential surface of the conductive member 3 and the outer circumferential surface of the motor shaft 5 are in surface contact. In addition, an outer circumferential groove 12 is formed on the outer circumferential surface of the conductive member 3 along the circumferential direction.

[0024] The conductive members 3 are housed one at a time between adjacent circumferentially bent portions 11 formed in the retainer 9. In this embodiment, four conductive members 3 are arranged at equal intervals in the circumferential direction. The number of conductive members 3 can be changed as appropriate, but it is preferable to have multiple members. The number of bent portions 11 formed in the retainer 9 is determined in accordance with the number of conductive members 3.

[0025] The material for the conductive member 3 can be metal, carbon, or resins such as polytetrafluoroethylene (PTFE) or polyetheretherketone (PEEK) with conductive materials such as carbon added, rubber, ceramics, or composite materials thereof. The volume resistivity of the conductive member 3 should preferably be 10 Ω·cm or less. The volume resistivity can be measured by the method described in JIS K 7194 (Resistivity Test Method for Conductive Plastics by Four-Probe Method). In addition, the surface of the conductive member 3 (especially the inner circumferential surface that slides against the motor shaft 5) can be treated with a coating to improve conductivity and wear resistance (for example, a conductive diamond-like carbon (DLC) film, a metal film (plating layer, etc.)).

[0026] As shown in Figure 3, an annular elastic member 13 is stretched across the outer peripheral groove 12 formed on the outer peripheral surface of each energizing member 3. The annular elastic member 13 is a member that biases the energizing member 3 radially inward toward the motor shaft 5 (see the arrow in Figure 3). In this embodiment, a garter spring made by processing a coiled steel wire into a ring shape is used as the annular elastic member 13. As an annular elastic member 13 other than a garter spring, for example, a circlip (C-type retaining ring) with a slit in part of the ring or an annular piece of rubber can also be used.

[0027] The current-carrying auxiliary member 4 is provided between the case body 2 and the current-carrying member 3 and is a member that assists in the conduction of current between the case body 2 and the current-carrying member 3. In the first example, the current-carrying auxiliary member 4 is provided so as to be adjacent to the current-carrying member 3 in the axial direction and uses a biasing member 4a that biases the current-carrying member 3 from the axial direction toward the case body 2 (outer ring portion 8). Specifically, the biasing member 4a is a leaf spring (hereinafter, the same reference numeral as the biasing member 4a is used). As shown in Figures 2, 6 and 7, the leaf spring 4a is a V-shaped member having an annular base portion 4a1 that contacts the inner surface of the retainer 9 and a biasing portion 4a2 that biases the current-carrying member 3 in the axial direction. As shown in Figure 5, the biasing portion 4a2 is formed corresponding to the circumferential position of the current-carrying member 3.

[0028] The shapes of the case body 2 (outer ring portion 8, retainer 9), the conductive member 3, and the annular elastic member 13 that constitute the energizing unit 1 can be determined as appropriate. However, as an example, if the shaft diameter of the motor shaft 5 is 35 mm, it is particularly preferable that the inner diameters of the outer ring portion 8 and the retainer 9 be 36.5 mm or larger in order to prevent the motor shaft 5 from coming into contact with the case body 2 (outer ring portion 8, retainer 9) due to wear of the conductive member 3 during long-term use. This is because the inner diameters of the outer ring portion 8 and the retainer 9 should be larger than the shaft diameter in order to prevent contact with the motor shaft 5. In this embodiment, the inner diameter of the outer ring portion 8 is 39 mm and the inner diameter of the retainer 9 is 40.6 mm. Also, as an example, if the axial width of the conductive member 3 is 2.5 mm, the coil diameter of the annular elastic member 13 (garter spring) can be 2 mm and the annular diameter can be 35 mm. The conductive component 3 is designed to have an initial radial width that is sufficient to withstand long-term use even if wear occurs over time.

[0029] The bearing 7, which is provided adjacent to the energizing unit 1, is a ball bearing as shown in Figure 1, comprising an outer ring 14, an inner ring 15 positioned on the inner diameter side of the outer ring 14, balls serving as rolling elements 16 provided between the outer ring 14 and the inner ring 15, and a cage 17 that holds the rolling elements 16 at predetermined intervals in the circumferential direction.

[0030] When using the power supply unit 1, the motor shaft 5 is inserted through the inner circumference of the power supply unit 1 (power supply member 3), and the outer circumference of the power supply unit 1 (case body 2) is fitted into the housing 6. The power supply member 3 of the power supply unit 1 is pressed radially inward against the motor shaft 5 by the biasing force of the annular elastic member 13. Furthermore, the power supply member 3 is pressed axially against the bent portion 10 formed on the outer ring portion 8 by the biasing force of the leaf spring 4a which is provided adjacent to the power supply member 3 in the axial direction.

[0031] In the first example of the current supply unit 1, a biasing member 4a (leaf spring 4a) acting as a current supply auxiliary member 4 assists in the current supply between the case body 2 and the current supply member 3. This prevents a gap from forming between the case body 2 and the current supply member 3, which would reduce the current supply state, and ensures a stable current supply state from the motor shaft 5 through the current supply member 3, the case body 2 (outer ring 8), to the housing 6. In particular, in the above-described current supply unit 1, the biasing member 4a (leaf spring 4a) is provided so as to be adjacent to the current supply member 3 in the axial direction, and the current supply member 3 is biased toward the case body 2 from the axial direction. This ensures an axial current supply path between the case body 2 and the current supply member 3, and further stabilizes the current supply state. By ensuring a stable current supply state in the current supply unit 1 in this way, electrolytic corrosion of the bearing 7 can be effectively suppressed.

[0032] Furthermore, the current-carrying unit 1 according to the first example has a configuration in which a bent portion 10 is formed on the outer ring portion 8, which is one of a pair of axially opposing wall portions that constitute the gap, and which bends inward toward the inside of the gap as it moves from the outer diameter side toward the inner diameter side. As a result, when the current-carrying member 3 is projected radially inward, the current-carrying member 3 can be brought into contact with the bent portion 10, and the current-carrying state between the case body portion 2 (outer ring portion 8) and the current-carrying member 3 can be made more stable.

[0033] Furthermore, the energizing unit 1 in the first example, by providing multiple energizing members 3, ensures that even if a problem occurs where the energizing function of some of the energizing members 3 is impaired, the energizing function of the other energizing members 3 can be maintained, thus reliably exhibiting an anti-corrosion effect. In addition, the self-aligning function of the multiple energizing members 3 stabilizes the contact state between the motor shaft 5 and each energizing member 3, further improving the anti-corrosion effect.

[0034] In the above, a configuration using a leaf spring 4a as the biasing spring 4a was shown, but a push nut as shown in Figure 8 or a wave washer as shown in Figure 9 can also be used as this biasing spring 4a (hereinafter, the push nut and wave washer will be denoted by the same reference numerals as the biasing member 4a). The push nut 4a is a member having an annular base portion 4a1 that contacts the inner surface of the retainer 9, and a biasing portion 4a2 that extends radially inward from the base portion 4a1 and is inclined in the axial direction, biasing the energizing member 3 in the axial direction. The wave washer 4a is an annular member with a wavy shape in the axial direction. In either configuration, similar to the leaf spring 4a, the energizing member 3 is biased from the axial direction toward the case body portion 2, and the effect of stabilizing the energized state of the energizing unit 1 is achieved.

[0035] Figure 10 shows a second example of the current-carrying unit 1 according to the present invention. The current-carrying unit 1 according to the second example has the same basic configuration as the current-carrying unit 1 according to the first example, but the current-carrying auxiliary member 4 is different. Specifically, in the second example, the current-carrying auxiliary member 4 is an elastic member 4b that has conductivity and is provided between the case body 2 and the current-carrying member 3, and biases the current-carrying member 3 toward the motor shaft 5. This elastic member 4b is a compression spring made of steel (hereinafter, the same reference numeral as the elastic member 4b is used). A pocket 18 is formed on the outer circumferential surface of the current-carrying member 3, and the compression spring 4b is attached to this pocket 18.

[0036] In the second example of the energizing unit 1, a conductive compression spring 4b is provided interposed between the case body 2 (retainer 9) and the energizing member 3, biasing the energizing member 3 radially toward the motor shaft 5. This ensures a radial energizing path between the case body 2 and the energizing member 3 via the compression spring 4b, thereby stabilizing the energized state.

[0037] Figure 11 shows a third example of the current-carrying unit 1 according to the present invention. The current-carrying unit according to the third example has the same basic configuration as the current-carrying unit 1 according to the first example, but the current-carrying auxiliary member 4 is different. Specifically, in the third example, a conductive wire 4c is used as the current-carrying auxiliary member 4 to connect the case body 2 and the current-carrying member 3. The end of the wire 4c on the case body 2 (retainer 9) side is fixed to the case body 2 by a conductive fixing means such as soldering or conductive adhesive. On the other hand, the end of the wire 4c on the current-carrying member 3 side is sandwiched between the case body 2 and the current-carrying member 3, and is in a state where it can slide radially relative to the current-carrying member 3. A deflection is formed in the middle part of the wire 4c, allowing the wire 4c to be displaced slightly in the radial direction.

[0038] In the third example, the power supply unit 1 is configured to directly connect the case body 2 and the power supply member 3 with a conductor 4c. This ensures a power supply path between the case body 2 and the power supply member 3 via the conductor 4c, thereby stabilizing the power supply state.

[0039] Figure 12 shows a fourth example of the current-carrying unit 1 according to the present invention. The current-carrying unit 1 according to the fourth example shares the same basic configuration as the current-carrying unit 1 according to the second example, but differs in that, in addition to the conductive elastic member 4b (compression spring 4b) as a current-carrying auxiliary member 4, a biasing spring 4a (leaf spring 4a) used in the first example is also added. In the current-carrying unit 1 according to the fourth example, a radial current-carrying path is secured between the case body 2 and the current-carrying member 3 via the compression spring 4b, and an axial current-carrying path is secured between the case body 2 and the current-carrying member 3 by the action of the leaf spring 4a, so the current-carrying state can be made more stable.

[0040] In the above embodiments, the motor shaft 5 is inserted through the axis of the energizing unit 1, and the energizing member 3 is biased radially inward by the annular elastic member 13 to slide against the motor shaft 5. However, conversely, if the motor shaft 5 is located on the outer diameter side of the energizing unit 1 and the housing 6 is located on the inner diameter side of the energizing unit 1, the energizing member 3 can also be biased radially outward by the annular elastic member 13.

[0041] Furthermore, in each of the above embodiments, a bent portion 10 was formed on the outer ring portion 8. However, if a stable energizing state can be ensured solely by the action of the energizing auxiliary member 4, the inner diameter edge of the outer ring portion 8 can be extended radially inward parallel to the inner diameter edge of the retainer 9 without forming a bent portion 10.

[0042] Figure 13 shows one embodiment of the bearing unit A according to the present invention. This bearing unit A is constructed by integrating the energizing unit 1 and the bearing 7 according to the first example. The flange formed on the outer ring portion 8 of the energizing unit 1 extends in the axial direction and is fitted to the outer diameter surface of the outer ring 14 of the bearing 7. By integrating the energizing unit 1 and the bearing 7 in this way to form the bearing unit A, weight reduction and narrowing of the width can be achieved. Furthermore, by making the size of this bearing unit A the same as the main bearing dimensions standardized in the Japanese Industrial Standard (JIS B 1512-1:2011), existing bearings can be replaced with the bearing unit A which has an anti-corrosion effect.

[0043] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0044] 1 Power supply unit 2. Case body 3. Conductive components 4. Power supply auxiliary member 4a. Biasing members (leaf springs, push nuts, wave washers) 4b Elastic component (compression spring) 4c conductor 7 Bearings 8 Outer ring 9 Litena 10. Bending section 12 Outer perimeter groove 13 Annular elastic member 14 Outer ring 15 Inner circle 16 Rolling elements 17 Cage A Bearing Unit

Claims

1. A conductive annular case body (2) having a gap that opens radially inward, A conductive current-carrying member (3) is provided within the gap and protrudes radially inward from the case body (2), A power supply assisting member (4) is provided between the case body (2) and the power supply member (3) to assist in the conduction of power between the case body (2) and the power supply member (3), A power supply unit having

2. The current-carrying auxiliary member (4) is provided so as to be adjacent to the current-carrying member (3) in the axial direction, and is a biasing member (4a) that biases the current-carrying member (3) toward the case body (2) from the axial direction, as described in claim 1.

3. The current-carrying unit according to claim 1, wherein the current-carrying auxiliary member (4) is a conductive elastic member (4b) that biases the current-carrying member (3) radially inward.

4. The current-carrying unit according to claim 1, wherein the current-carrying auxiliary member (4) is a conductive wire (4c) that connects the case body (2) and the current-carrying member (3).

5. The energizing unit according to claim 1, wherein at least one of a pair of axially opposing wall portions of the case body portion (2) has a bent portion (10) formed thereon that bends inward toward the inside of the gap as it moves from the outer diameter side toward the inner diameter side.

6. The current-carrying unit according to claim 1, wherein a plurality of the current-carrying members (3) are provided in the circumferential direction.

7. The energizing unit according to claim 1, wherein the case body portion (2) comprises an annular outer ring portion (8) having a flange extending in one direction in the axial direction on its outer peripheral edge, and a retainer (9) that fits axially into the outer ring portion (8) and has a flange extending in the opposite direction to the one side in the axial direction on its outer peripheral edge.

8. The current-carrying unit according to claim 1, wherein the current-carrying member (3) is made of a conductive material formed from a metal, carbon, or a resin, rubber, ceramics, or a composite material thereof to which a conductive material has been added, and its volume resistivity is 10 Ω·cm or less.

9. The current-carrying unit according to claim 1, wherein an annular elastic member (13) is provided, which is arranged in an outer peripheral groove (12) formed on the outer peripheral surface of the current-carrying member (3) and biases the current-carrying member (3) radially inward.

10. A power supply unit (1) according to any one of claims 1 to 9, A bearing (7) having an outer ring (14), an inner ring (15) disposed on the inner diameter side of the outer ring (14), rolling elements (16) provided between the outer ring (14) and the inner ring (15), and a cage (17) that holds the rolling elements (16) at predetermined intervals in the circumferential direction, wherein the outer ring (14) is positioned to contact the energizing unit (1), A bearing unit having

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