Insulated rolling bearing and its insulating ring

Abstract

To eliminate the need for masking and cleaning to prevent dust from entering the interior during the manufacturing of insulated rolling bearings. [Solution] A rolling bearing comprising an outer ring 1, an inner ring 2, and a ball 3 interposed between them, wherein an annular insulating ring 4 is fitted to surround both sides of the outer circumferential surface of the outer ring 1, the insulating ring 4 consists of two symmetrically shaped semi-ring members 5 divided in the circumferential direction, the semi-ring members 5 being elastically deformable and having alternating engaging claws 6 protruding in the circumferential direction and engaging grooves 7 recessed at both ends thereof, the semi-ring members 5 being inserted radially into the outer ring 1, and the pair of semi-ring members 5 being joined by the engagement of one engaging claw 6 and the other engaging groove 7, thereby fixing the insulating ring 4 to the outer ring 1.

Description

Technical Field

[0001] This invention relates to a rolling bearing having an insulating function for blocking the flow of electricity and an insulating ring for exerting its function.

Background Art

[0002] In electric motors mounted on electric vehicles such as electric vehicles (EVs) and hybrid vehicles (HEVs), and in speed reducers (e-axles) integrated with electric motors, rolling bearings having an insulating function for blocking the flow of electricity between components are required.

[0003] As a rolling bearing having such an insulating function, Patent Document 1 below describes one as shown in FIG. 10.

[0004] This rolling bearing is a deep groove ball bearing including an outer ring 51, an inner ring 52, and a plurality of balls 53 as rolling elements interposed therebetween. Insulating films 54, 55 are formed on the outer ring 51 and the inner ring 52 at portions where the balls 53 and their retainers do not contact. These insulating films 54, 55 are formed by insert molding in which, in a process before assembling the rolling bearing, the outer ring 51 and the inner ring 52, which are metal parts, are previously placed inside a mold, and a highly insulating resin is injected and adhered around the outer ring 51 and the inner ring 52, respectively.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in the method of forming an insulating coating by insert molding as described above, if debris enters the inside of the rolling bearing, the bearing's function will be impaired. Therefore, it is necessary to mask the raceway surfaces that the rolling elements of the outer and inner rings contact during gate removal or post-processing after insert molding, or to clean the inside after processing, which contributes to increased costs.

[0007] Therefore, the objective of this invention is to eliminate the need for masking and cleaning to prevent the ingress of debris into the interior during the manufacturing of rolling bearings equipped with insulating properties. [Means for solving the problem]

[0008] To solve the above-mentioned problems, the rolling bearing according to this invention comprises an outer ring, an inner ring, and rolling elements interposed between them, and an annular insulating ring is fitted so as to surround the outer circumferential surface and both sides of the outer ring, The insulating ring consists of a plurality of arc-shaped members divided in the circumferential direction, and each of the plurality of arc-shaped members is elastically deformable and has alternating engaging claws protruding in the circumferential direction and engaging grooves that engage with them at both ends. The plurality of arc-shaped members are arranged to cover the outer ring, and the plurality of arc-shaped members are joined together by the engagement of one of their engaging claws and the other of their engaging grooves, thereby fixing them to the outer ring (Configuration 1).

[0009] Furthermore, in the insulated rolling bearing of configuration 1, the arc-shaped member is a symmetrical semi-ring member divided into two in the circumferential direction (configuration 2).

[0010] Furthermore, in the insulated rolling bearing of configuration 1, the engaging claws of the semi-ring member of the insulating ring protrude from both ends that serve as the reference ends for the abutting of the pair of semi-ring members, with a central angle of 5° or less in the circumferential direction (configuration 3).

[0011] Furthermore, in the insulated rolling bearing of configuration 3, the semi-ring member of the insulating ring has a guide surface formed at the tip of the engaging claw that is inclined to cut in from the outer diameter side to the inner diameter side (configuration 4).

[0012] Furthermore, in the arc-shaped member of the insulating ring of configuration 1, side walls are provided extending radially inward from both sides of the peripheral wall along the outer circumferential surface of the outer ring, so as to be along the side surface of the outer ring, and a snap fit or flange is provided on the inner diameter portion of the side wall, and the snap fit or flange fits onto the inner circumferential surface of the end of the outer ring (configuration 5).

[0013] Furthermore, in any of the insulated rolling bearings of configurations 1 to 5, the material of the insulating ring includes polyamide resin, polyetheretherketone resin, or polyphenylene sulfide resin (configuration 6).

[0014] Furthermore, in any of the insulated rolling bearings of configurations 1 to 6, which are applied to motors, transmissions, or reducers, the insulating ring prevents electricity from flowing from the outer ring to the inner ring, or from the inner ring to the outer ring (configuration 7).

[0015] Furthermore, the insulating ring for an insulated rolling bearing according to this invention is an insulating ring applied to an insulated rolling bearing that has an outer ring, an inner ring, and rolling elements interposed between them, It consists of multiple arc-shaped members divided in the circumferential direction, and each arc-shaped member is elastically deformable and has alternating engaging claws protruding in the circumferential direction and engaging grooves recessed therein at both ends. The arc-shaped member is inserted radially into the outer ring, and the pair of arc-shaped members are joined together by the engagement of one engaging claw and the other engaging groove, thereby fixing them to the outer ring (Configuration 8).

[0016] Furthermore, in the insulating ring of Configuration 8, the member having the arc shape is a semi-ring member with a symmetrical shape that is divided into two in the circumferential direction (Configuration 9).

Advantages of the Invention

[0017] According to this invention, by inserting a member having an arc shape (semi-ring member) divided in the circumferential direction of the insulating ring into the outer ring from the radial direction and coupling the members having an arc shape (semi-ring members) to each other by engaging the engaging claws and the engaging grooves at both ends thereof, it is possible to block the electric current flowing through the rolling bearing from the housing on the outer ring side to the shaft on the inner ring side or vice versa.

[0018] Therefore, in manufacturing, processes such as masking the raceway surfaces where the rolling elements of the outer ring and the inner ring come into contact or cleaning the interior after processing, as in the method of forming an insulating film by insert molding, become unnecessary, and it can be manufactured at a low cost. Also, the insulation performance is stable, and it is possible to prevent the electric corrosion of each component of the rolling bearing.

[0019] In addition, since the insulating ring according to this invention can be fitted later to a completed rolling bearing, there is no need to change the manufacturing process of the conventional rolling bearing, and no dust enters the interior during the manufacturing process of the rolling bearing.

Brief Description of the Drawings

[0020] <小 [Figure 1] Perspective view showing the state of mounting the insulating ring of the rolling bearing according to an embodiment of this invention [Figure 2] Perspective view showing the semi-ring member of the insulating ring described above [Figure 3] Vertical front view showing the semi-ring member of the insulating ring described above [Figure 4] Perspective view showing the mounting process of one of the semi-ring members described above [Figure 5] Vertical front view schematically showing the mounting process of one of the semi-ring members described above [Figure 6] Perspective view showing the mounted state of one of the semi-ring members described above [Figure 7]A schematic longitudinal front view showing the process of attaching the other semi-ring member as shown above. [Figure 8] A perspective view showing a semi-ring member of another insulating ring according to an embodiment of this invention. [Figure 9] Partial cross-sectional view showing a rolling bearing fitted with the same semi-ring member. [Figure 10] Partial cross-sectional view showing a rolling bearing having an insulating coating as described in Patent Document 1. [Modes for carrying out the invention]

[0021] Hereinafter, embodiments of this invention will be described based on the attached drawings.

[0022] As shown in Figure 1, this rolling bearing is a deep groove ball bearing comprising an outer ring 1, an inner ring 2, and a cage containing multiple balls 3 as rolling elements interposed between them, with an annular insulating ring 4 fitted around both sides of the outer ring 1 from the outer circumference. Here, the direction around the axis of rotation of the deep groove ball bearing is called the circumferential direction, and the direction perpendicular to the axis of rotation is called the radial direction. Furthermore, this insulating ring 4 can be used not only for deep groove ball bearings, but also for other rolling bearings such as angular contact ball bearings and cylindrical roller bearings.

[0023] The insulating ring 4 is made of polyamide resin, polyetheretherketone resin, or polyphenylene sulfide resin, and consists of a symmetrical semi-ring member 5 that is divided into two parts in the circumferential direction. This material is not limited to being made solely of the materials described above, but may be made of materials other than the resins described above, as long as they have insulating properties and contain other components.

[0024] Furthermore, it may contain fiber reinforcement materials. The type of reinforcement material can be glass fiber, carbon fiber, etc., or it may contain both.

[0025] The reinforcing material used in this formulation preferably has a number-average fiber length of 100 μm to 600 μm. If it is less than 100 μm, the decrease in strength, expressed as flexural modulus or Young's modulus, becomes significant. If it exceeds 600 μm, the strength decreases, potentially leading to fatigue failure. When the number-average fiber length is within the above range, deformation can be suppressed and the material can be used even in environments with high loads.

[0026] Furthermore, it is preferable that the standard deviation of fiber length is 500 μm or less. A smaller standard deviation is preferable because it results in fewer irregularly long fibers and thus a higher reinforcing effect.

[0027] Furthermore, the number-average fiber diameter of the reinforcing material is preferably between φ4μm and φ18μm. If it is thinner than φ4μm, the strength-enhancing effect as a reinforcing material may be insufficient. On the other hand, if it exceeds φ18μm, it is too thick and becomes difficult to handle as a reinforcing material.

[0028] Furthermore, the reinforcing material content is preferably between 15% by mass and 50% by mass. Below 15% by mass, even if the reinforcing material is within the above range, there is a high risk that the strength-enhancing effect will be insufficient. On the other hand, above 50% by mass, the resin becomes difficult to handle.

[0029] As shown in Figures 2 and 3, the semi-ring member 5 is elastically deformable and has alternating engagement claws 6 that protrude circumferentially and engagement grooves 7 that are recessed at both ends. At one end of the semi-ring member 5, one engagement groove 7 is formed between two engagement claws 6, and at the other end, one engagement claw 6 is formed between two engagement grooves 7. By increasing the number of engaging claws 6 and engaging grooves 7 in a comb-like pattern, it is possible to accommodate rolling bearings with a wider axial width. Furthermore, this comb-like arrangement reduces the rigidity of each engaging claw 6, making them more easily deformable. As a result, when mounting them onto the outer ring 1, as described later, they can be easily inserted radially into the outer ring 1.

[0030] In this semi-ring member 5, the central angle α of the side walls 5b that extend radially inward along the side surface of the outer ring 1 from both sides of the peripheral wall 5a along the outer circumferential surface of the outer ring 1 is set to 180°.

[0031] If the side wall 5b extends inward from the side of the outer ring 1, it will not only provide insulation but also function as a non-contact sealing plate to prevent dust from entering.

[0032] Furthermore, the engaging claws 6 protrude from both ends of the side wall 5b, which serves as the reference end for the abutting of the pair of semi-ring members 5, so that the central angle β is 5° or less in the circumferential direction. The tip of the engaging claw 6 has a guide surface 6a that is inclined to cut inward from the outer diameter side to the inner diameter side.

[0033] The reason why the central angle β of the protruding portion of the engaging claw 6 is set to 5° or less is that, as will be described later, when the semi-ring member 5 is attached to the outer ring 1, if the central angle β is greater than 5°, the amount of deformation of the outer ring 1 will increase, stress will concentrate at the base of the engaging claw 6, and there is a risk that the engaging claw 6 may break.

[0034] Furthermore, if the central angle β is too small, the engaging claws 6 at both ends of the semi-ring member 5 may not be able to sufficiently grip the outer ring 1, potentially resulting in insufficient fixing force of the semi-ring member 5 to the outer ring 1.

[0035] To attach such a semi-ring member 5 to the outer ring 1, as shown in Figures 4 and 5, first, one of the semi-ring members 5 is inserted radially into the outer ring 1 while deforming it so that the radial distance between its ends widens.

[0036] At this time, the guide surface 6a of the engaging claw 6 slides smoothly along the outer circumferential surface of the outer ring 1, and the semi-ring member 5 deforms on its own, allowing insertion into the outer ring 1 to proceed. Therefore, there is no need to apply force to the semi-ring member 5 to expand its diameter. For this reason, assembly can be easily performed manually without requiring much force. Furthermore, the assembly process of fitting the insulating ring 4 onto the outer ring 1 can be performed not only manually but also automatically by an assembly device.

[0037] Then, when the engaging claws 6 at both ends extend beyond half the circumference of the outer ring 1, as shown in Figure 6, the semi-ring member 5 returns to its elastic state, and the engaging claws 6 at both ends grip the outer ring 1, holding it in a position that covers the outer ring 1.

[0038] Subsequently, as shown in Figure 7, when the other semi-ring member 5 is inserted radially into the outer ring 1 while being deformed in the same way as the first semi-ring member 5 so that the radial distance between its ends widens, the pair of semi-ring members 5 are joined together by the engagement of one of their engaging claws 6 and the other engaging groove 7, and the insulating ring 4 is fixed to the outer ring 1 (see Figure 1).

[0039] Incidentally, as shown in Figure 8, multiple snap-fits 8 may be provided at circumferential intervals on the inner diameter portion of the side wall 5b of the semi-ring member 5, and as shown in Figure 9, these snap-fits 8 may be fitted onto the inner circumferential surface 9 (outer portion of the seal groove) of the end of the outer ring 1.

[0040] This improves the fixing force of the semi-ring member 5 to the outer ring 1, preventing the insulating ring 4 from falling off the rolling bearing.

[0041] Furthermore, if a flange portion extending axially inward and continuous in the circumferential direction is provided on the inner diameter portion of the side wall 5b of the semi-ring member 5, and this flange portion is fitted to the inner circumferential surface 9 of the end of the outer ring 1, the fixing force of the semi-ring member 5 to the outer ring 1 is improved, and the insulating ring 4 is prevented from falling off the rolling bearing.

[0042] In the rolling bearing described above, the semi-ring members 5, which are divided in the circumferential direction of the insulating ring 4, are inserted radially into the outer ring 1, and the pair of semi-ring members 5 are connected by the engagement of the engaging claws 6 and engaging grooves 7 at both ends of them, thereby preventing the flow of electricity from the housing on the outer ring 1 side through the shaft on the inner ring side or the rolling bearing in the opposite direction.

[0043] Specifically, without forming an insulating coating on the outer ring 1 or inner ring 2, the volume resistivity of the insulating ring 4 is set to 10. 6The resistance can be set to Ωcm or higher, the insulation resistance value of the rolling bearing as a product can be set to 1MΩ or higher, and the withstand voltage can be set to 200V or higher.

[0044] Therefore, during manufacturing, processes such as masking the raceway surfaces in which the rolling elements of the outer ring 1 and inner ring 2 make contact, or cleaning the inside after processing, are unnecessary, as is done in methods where an insulating coating is formed by insert molding, allowing for low-cost manufacturing. In addition, the insulating performance is stable, and galvanic corrosion of each component of the rolling bearing can be prevented.

[0045] The evaluation of electrolytic corrosion resistance is performed using a measuring device that includes a power supply unit capable of applying voltage to a rolling bearing and changing the magnitude of that voltage, a voltage measuring unit for measuring the voltage between the inner and outer rings, and a current measuring unit for measuring the current flowing between the inner and outer rings. With the inner and outer rings rotating relative to each other, a voltage is applied to the rolling bearing by the power supply unit and the voltage is gradually increased to generate a single discharge between the inner or outer ring racing surface and the rolling element. Based on the test results, it is determined whether or not ridge marks (striped irregularities) due to electrolytic corrosion may occur on the inner or outer ring racing surface of the rolling element.

[0046] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. Accordingly, the scope of the invention is indicated by the claims and all modifications within the meaning and scope equivalent to the claims are intended. [Explanation of symbols]

[0047] 1 Outer ring 2 Inner ring 3 Balls (rolling elements) 4 Insulating rings 5. Semi-ring member (member having an arc shape) 5a Peripheral wall 5b side wall 6. Engaging claws 6a Guidance surface 7. Engagement groove 8 Snap-Fit 9 End inner circumferential surface α Central angle (sidewall of semi-ring component) β central angle (coupling claw)

Claims

1. An insulated rolling bearing comprising an outer ring, an inner ring, and rolling elements interposed between them, wherein an annular insulating ring is fitted so as to surround the outer circumferential surface and both sides of the outer ring, The insulating ring consists of a plurality of arc-shaped members divided in the circumferential direction, and each of the plurality of arc-shaped members is elastically deformable and has alternating engaging claws protruding in the circumferential direction and engaging grooves that engage with them at both ends. An insulated rolling bearing characterized in that the plurality of arc-shaped members are arranged to cover the outer ring, and the plurality of arc-shaped members are connected to the outer ring by the engagement of one of their engaging claws and the other of their engaging grooves.

2. The insulating rolling bearing according to claim 1, characterized in that the member having the arc shape is a symmetrical semi-ring member divided into two in the circumferential direction.

3. The insulating rolling bearing according to claim 2, characterized in that the engaging claws of the semi-ring member of the insulating ring protrude from both ends that serve as the reference ends for the abutting of the pair of semi-ring members, such that the central angle is 5° or less in the circumferential direction.

4. The insulating rolling bearing according to claim 3, characterized in that, in the semi-ring member of the insulating ring, a guide surface is formed at the tip of the engaging claw that is inclined to cut in from the outer diameter side to the inner diameter side.

5. The insulating rolling bearing according to claim 1, wherein the member having the arc shape of the insulating ring is provided with side walls extending radially inward from both sides of a circumferential wall along the outer circumferential surface of the outer ring so as to be along the side surface of the outer ring, a snap fit or flange is provided on the inner diameter portion of the side wall, and the snap fit or flange fits onto the inner circumferential surface of the end portion of the outer ring.

6. The insulating rolling bearing according to any one of claims 1 to 5, characterized in that the material of the insulating ring includes a polyamide resin, a polyetheretherketone resin, or a polyphenylene sulfide resin.

7. The insulated rolling bearing according to claim 6, which is applied to a motor, transmission, or reducer, and is characterized in that the insulating ring prevents electricity from flowing from the outer ring to the inner ring, or from the inner ring to the outer ring.

8. An insulating ring applicable to an insulated rolling bearing comprising an outer ring, an inner ring, and rolling elements interposed between them, It consists of multiple arc-shaped members divided in the circumferential direction, and each arc-shaped member is elastically deformable and has alternating engaging claws protruding in the circumferential direction and engaging grooves recessed therein at both ends. An insulating ring characterized in that the arc-shaped member is inserted radially into the outer ring, and the pair of arc-shaped members are joined together by the engagement of one engaging claw and the other engaging groove, thereby being fixed to the outer ring.

9. The insulating ring according to claim 8, characterized in that the member having the arc shape is a symmetrical semi-ring member divided into two in the circumferential direction.

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