Bearing assembly and in-wheel working device comprising the same and manufacturing method of bearing assembly

Abstract

The present invention relates to a bearing assembly, an in-wheel drive device including the same, and a method for manufacturing a bearing assembly. The in-wheel drive device according to the present invention comprises a motor shaft, an inner ring portion including a first inner ring and a second inner ring mounted on the radial outer surface of the central axis of the motor shaft and arranged along the central axis, an outer ring portion mounted spaced outwardly in the radial direction from the inner ring portion, and a rolling element provided between the inner ring portion and the outer ring portion. The first inner ring is provided to be inserted into the space between the motor shaft and the rolling element to apply a preload to the rolling element.

Description

Technology Field

[0001] The present invention relates to a bearing assembly, an in-wheel drive device including the same, and a method for manufacturing a bearing assembly. More specifically, the invention relates to a bearing assembly in which a preload is applied stably to improve stability and reliability, an in-wheel drive device including the same, and a method for manufacturing a bearing assembly. Background Technology

[0002] Generally, a vehicle's in-wheel drive system refers to a vehicle system in which a motor is installed inside the wheel, allowing each wheel to be driven directly by the motor. Bearings are installed in the motor assembly of the vehicle's in-wheel drive system. A bearing includes a shaft portion as a rotating element, an inner ring fixed to the shaft portion, an outer ring as a non-rotating element, and rolling elements (bearing balls) provided between the inner and outer rings.

[0003] Generally, bearings can be installed with a preload applied to the rolling elements by generating an axial force on the inner ring. Preload refers to the load applied to the rolling elements in advance to increase the bearing's stiffness and maintain proper clearance. Since preload has a significant impact on bearing life, it is important to apply an appropriate preload to the bearing.

[0004] A conventional bearing installation structure includes a nut member that applies an appropriate preload to the rolling element and fixes the inner ring to the shaft, and a washer installed between the nut member and the bearing to prevent the nut member from loosening. According to the conventional bearing installation structure, there was a problem in that axial force loss occurred at multiple locations such as the nut member, washer, and bearing, and the axial force was scattered in proportion to the contact area at the contact portion of each member.

[0005] If the dispersion of axial force—that is, the error range of the axial force—expands, it becomes difficult to generate a constant preload on the rolling elements. Furthermore, if an appropriate preload is not consistently applied to the bearings, it adversely affects the bearing lifespan, leading to a problem of reduced durability.

[0006] Therefore, there is a need for technology that can generate a more stable preload on the rolling elements equipped in the bearing, thereby promoting bearing stability, quality improvement, and reliability. The problem to be solved

[0007] The present invention is devised to solve the aforementioned problems and aims to provide a bearing assembly that mounts an inner ring portion to a motor shaft by means of a first inner ring and simultaneously applies a preload directly to a rolling element while in contact with the rolling element, an in-wheel drive device including the same, and a method for manufacturing the bearing assembly.

[0008] In addition, the present invention aims to provide a bearing assembly that stably applies preload to a rolling element by reducing axial force and minimizing the dispersion of axial force, an in-wheel drive device including the same, and a method for manufacturing the bearing assembly.

[0009] In addition, the present invention aims to provide a bearing assembly that implements stability, reliability, and quality improvement, an in-wheel drive device including the same, and a method for manufacturing the bearing assembly. means of solving the problem

[0010] To achieve the above objective, the in-wheel drive device according to the present invention comprises a motor shaft, an inner ring portion including a first inner ring and a second inner ring mounted on the radially outer surface of the central axis of the motor shaft and arranged along the central axis, an outer ring portion mounted spaced outwardly from the inner ring portion in the radial direction, and a rolling element provided between the inner ring portion and the outer ring portion, wherein the first inner ring is inserted into the space between the motor shaft and the rolling element to apply a preload to the rolling element.

[0011] The motor shaft may include a shaft portion provided in the direction of the central axis and into which the inner ring portion is fitted, and a flange portion protruding radially from the shaft portion, provided to face the first inner ring with the second inner ring in between, and provided to support the second inner ring.

[0012] The first inner ring may include a contact portion provided on the radial inner side of the outer ring portion and configured to contact the rolling element, and a control portion that extends from the contact portion in the direction of the central axis and is configured to be exposed to the outside of the outer ring portion in the direction of the central axis.

[0013] The first inner ring may further include a plurality of adjustment protrusions that are formed to protrude radially from the outer surface of the adjustment part and are spaced apart in the circumferential direction of the adjustment part.

[0014] The first inner ring can be press-fitted and fixed to the outer surface of the motor shaft.

[0015] A first screw thread is formed on the outer surface of the motor shaft, and a second screw thread corresponding to the first screw thread may be formed on the inner surface facing the motor shaft so as to be screw-coupled to the motor shaft.

[0016] The first inner ring may include an oil supply groove formed to be recessed to guide the supplied lubricant into the space between the outer ring portion and the inner ring portion.

[0017] The above oil supply groove may include a first flow groove that is continuously formed along the outer surface of the first inner ring from the upper surface of the first inner ring to form a first oil flow path for supplying lubricant to the rolling element.

[0018] The first flow grooves are formed in a plurality of spaced-apart locations along the circumferential direction of the first inner ring, and may be arranged between adjacent control protrusions.

[0019] The above oil supply groove may include a second flow groove that is continuously formed along the inner surface of the first inner ring from the lower surface of the first inner ring to form a second oil flow path for supplying lubricant to the rolling element.

[0020] The second flow grooves are formed spaced apart in the circumferential direction of the first inner ring, and may be formed at a position corresponding to the adjustment projection on the inner surface of the first inner ring.

[0021] The above rolling element may include a first rolling element provided between the first inner ring and the outer ring portion, and a second rolling element provided between the second inner ring and the outer ring portion and spaced apart from the first rolling element in the direction of the central axis.

[0022] Meanwhile, the bearing assembly according to the present invention is mounted on the radial outer surface of the central axis of a motor shaft and comprises an inner ring portion including a first inner ring and a second inner ring arranged along the central axis, an outer ring portion mounted spaced outwardly from the inner ring portion in the radial direction, and a rolling element provided between the inner ring portion and the outer ring portion, wherein the first inner ring may be provided to be inserted into the space between the motor shaft and the rolling element to apply a preload to the rolling element.

[0023] Meanwhile, the method for manufacturing a bearing assembly according to the present invention may include a first step of mounting a second inner ring, an outer ring portion spaced radially outward from the second inner ring, and a rolling element provided between the second inner ring and the outer ring portion on the radial outer surface of the central axis of a motor shaft, and a second step of inserting a first inner ring into the space between the motor shaft and the rolling element and fixing the first inner ring to the motor shaft so that a preset preload is applied to the rolling element.

[0024] The first inner ring includes a contact portion and a control portion extending from the contact portion in the direction of the central axis, and the second step may be performed such that the contact portion is inserted into the radially inner side of the outer ring portion to contact the rolling element, and the control portion is exposed to the outside of the outer ring portion in the direction of the central axis. Effects of the invention

[0025] In accordance with an embodiment of the present invention, the first inner ring is formed integrally with the adjustment part and the contact part, thereby enabling it to simultaneously perform the function of a conventional inner ring and the function of a nut member that fixes the inner ring and applies preload. Accordingly, the first inner ring according to an embodiment of the present invention can directly apply preload to the rolling element while in contact with the rolling element.

[0026] Accordingly, according to an embodiment of the present invention, compared to a structure in which axial force is transmitted in multiple stages through a conventional nut member and a washer member, the loss of axial force can be reduced and the dispersion of axial force can be minimized, thereby allowing preload to be applied more stably to the rolling element.

[0027] By utilizing the present invention, the stability, reliability, and quality improvement of the bearing assembly can be achieved.

[0028] In addition, by using the present invention, there is no need to separately assemble nut members and washer members, etc., so costs can be reduced and installation can be performed smoothly even in confined spaces. Brief explanation of the drawing

[0029] FIG. 1 is a cross-sectional perspective view of a bearing assembly according to one embodiment of the present invention. FIG. 2 is an exploded perspective view illustrating an inner ring and an outer ring according to one embodiment of the present invention. FIG. 3 is a perspective view illustrating an inner ring portion according to one embodiment of the present invention. Figure 4 is an enlarged cross-sectional perspective view illustrating part B of Figure 2. FIG. 5 is a partially enlarged perspective view showing an enlarged portion of a bearing assembly according to one embodiment of the present invention. FIG. 6 is a drawing for explaining an oil supply groove according to an embodiment of the present invention, and is a drawing of the inner ring viewed from above. FIG. 7 is a cross-sectional perspective view of a bearing assembly according to one embodiment of the present invention, and is a drawing for explaining the first flow groove. FIG. 8 is an enlarged cross-sectional perspective view illustrating part A of FIG. 1, and is a drawing for explaining the second flow groove. Specific details for implementing the invention

[0030] Hereinafter, embodiments of the present invention will be described in detail according to the attached drawings.

[0031] First, the embodiments described below are suitable for illustrating the technical features of the bearing assembly of the present invention, the in-wheel drive device including the same, and the method for manufacturing the bearing assembly. However, the present invention is not limited to the embodiments described below, nor are the technical features of the present invention limited by the described embodiments; various modifications are possible within the technical scope of the present invention.

[0033] FIG. 1 is a cross-sectional perspective view of a bearing assembly according to one embodiment of the present invention, FIG. 2 is an exploded perspective view showing an inner ring and an outer ring according to one embodiment of the present invention, FIG. 3 is a perspective view showing an inner ring according to one embodiment of the present invention, FIG. 4 is an enlarged cross-sectional perspective view showing part B of FIG. 2, and FIG. 5 is a partially enlarged perspective view showing an enlarged part of a bearing assembly according to one embodiment of the present invention.

[0034] FIG. 6 is a drawing for explaining an oil supply groove according to an embodiment of the present invention, and is a drawing of the inner ring portion viewed from above; FIG. 7 is a cross-sectional perspective view of a bearing assembly according to an embodiment of the present invention, and is a drawing for explaining a first flow groove; FIG. 8 is an enlarged cross-sectional perspective view showing portion A of FIG. 1 enlarged, and is a drawing for explaining a second flow groove.

[0035] Referring to FIGS. 1 to 8, a bearing assembly (100) according to one embodiment of the present invention includes a motor shaft (200), an inner ring portion (300), an outer ring portion (400), and a rolling element (500). For example, a bearing assembly (100) according to one embodiment of the present invention may be applied to an in-wheel drive device (10), but is not limited thereto, and may be applied to various structures for rotatably supporting a rotating element with respect to a non-rotating element.

[0036] The motor shaft (200) is provided in a motor part located inside the in-wheel drive unit and can rotate by the driving force provided by the motor part. A hollow may be formed inside the motor shaft (200), and a drive shaft that transmits engine power to a wheel hub (not shown) may be assembled in the hollow, but is not limited thereto.

[0037] The inner ring portion (300) is mounted on the radial outer surface of the central axis of the motor shaft (200) and includes a first inner ring (310) and a second inner ring (320) arranged along the central axis. The first inner ring (310) and the second inner ring (320) can be arranged along the axial direction of the central axis of the motor shaft (200) by being sequentially fitted onto the motor shaft (200). For example, the first inner ring (310) can be mounted on the vehicle body side, and the second inner ring (320) can be mounted on the wheel side. A track surface in which the rolling element (500) contacts can be formed on the outer surface of the inner ring portion (300).

[0038] As in the illustrated embodiment, the inner ring portion (300) may consist of two inner rings, but is not limited thereto, and depending on the arrangement of the rolling element (500), a plurality of second inner rings (320) may be provided to provide three or more inner rings.

[0039] The outer ring portion (400) is mounted so as to be spaced radially outward from the inner ring portion (300). The outer ring portion (400) is a non-rotating element that is fixedly coupled to the vehicle body directly or indirectly, and may have a track surface on its radial inner circumference that contacts the rolling element (500). The track surface formed on the inner circumference of the outer ring portion (400) may be installed to face the track surface formed on the outer circumference of the inner ring portion (300).

[0040] The rolling element (500) is provided between the inner ring portion (300) and the outer ring portion (400). Specifically, the rolling element (500) is positioned between the track surface formed on the inner circumference of the outer ring portion (400) and the track surface formed on the outer circumference of the inner ring portion (300), so that the inner ring portion (300) and the motor shaft (200) can be connected to rotate relative to the outer ring portion (400).

[0041] For example, the electric element (500) may include a first electric element (510) and a second electric element (520).

[0042] The first rolling element (510) may be provided between the first inner ring (310) and the outer ring portion (400). Additionally, the second rolling element (520) may be provided between the second inner ring (320) and the outer ring portion (400) and may be arranged spaced apart from the first rolling element (510) in the direction of the central axis. However, the structure of the rolling element (500) is not limited to the above description and may be modified according to the configuration of the inner ring portion (300), etc.

[0043] Here, the first inner ring (310) is inserted into the space between the motor shaft (200) and the rolling element (500) to apply a preload to the rolling element (500).

[0044] Here, preload refers to a load applied in advance to the rolling element (500) to increase the rigidity of the bearing assembly (100) and maintain an appropriate clearance. Since preload has a significant effect on the lifespan of the bearing, it is important to apply an appropriate preload to the bearing.

[0045] A conventional bearing installation structure includes a nut member that applies an appropriate preload to the rolling element and fixes the inner ring to the motor shaft, and a washer member installed between the nut member and the bearing to prevent the nut member from loosening. According to the conventional bearing installation structure, there was a problem in that axial force loss occurred at multiple locations, such as the nut member, the washer member, and the inner ring, and the axial force was scattered in proportion to the contact area of ​​the contact portion between each member.

[0046] Specifically, in a conventional bearing structure, a bearing is press-fitted into the shaft of a motor shaft, and a washer member and a nut member are sequentially installed on the shaft. As the nut member is screw-fastened to the wheel shaft, a fastening torque is generated, which can cause an axial force to be generated in the nut member. Then, an axial force is generated in the inner ring by the axial force of the nut member, and this can cause a preload to be generated in the rolling element of the bearing.

[0047] According to such conventional bearing installation structures, there is a problem of axial force loss because force is transmitted at the contact area between the nut member and the washer member and at the contact area between the washer member and the inner ring. In addition, there was a problem of axial force being distributed in proportion to the contact area between the nut member and the washer member and the contact area between the washer member and the inner ring.

[0048] If the dispersion of axial force—that is, the error range of the axial force—expands, the range of preload can also widen. In other words, if the axial force is dispersed, it is difficult to generate a constant preload on the rolling element. If a constant preload is not applied to the rolling element, it adversely affects the lifespan of the bearing, leading to a problem where the stability and reliability of the bearing assembly are reduced. An embodiment of the present invention can solve this problem by applying a preload directly to the rolling element through a first inner ring, without using intermediaries such as a nut member and a washer member as in the prior art. An embodiment of the present invention will be described in detail below.

[0049] First, referring to FIG. 1, the motor shaft (200) may include a shaft portion (210) and a flange portion (220).

[0050] The shaft portion (210) is provided with the central axis direction extended in the longitudinal direction, and the inner ring portion (300) can be fitted. Specifically, the inner ring portion (300) can be fitted on the outer surface of the shaft portion (210), and the drive shaft of the motor portion can be inserted in the central axis direction of the shaft portion (210).

[0051] The flange portion (220) may be provided to protrude radially from the shaft portion (210), face the first inner ring (310) with the second inner ring (320) in between, and support the second inner ring (320). That is, the flange portion (220) may protrude from the outer surface of the shaft portion (210) and serve to support the second inner ring (320).

[0052] The first inner ring (310) may include a contact portion (313) and a control portion (311).

[0053] The contact portion (313) may be provided on the radial inner side of the outer ring portion (400) to be able to contact the rolling element (500). The adjustment portion (311) may be provided so as to extend from the contact portion (313) in the direction of the central axis and be exposed to the outside of the outer ring portion (400) in the direction of the central axis.

[0054] Specifically, the first inner ring (310) is divided into a contact portion (313) and an adjustment portion (311), and the contact portion (313) and the adjustment portion (311) are formed integrally. The contact portion (313) is mounted on the motor shaft (200) and contacts the rolling element (500), and the adjustment portion (311) extends from the contact portion (313) toward the vehicle body and is provided to be exposed to the outside of the outer ring portion (400). Since the adjustment portion (311) is provided to be exposed to the outside of the outer ring portion (400), a tool for mounting can be attached when mounting the first inner ring (310) to the motor shaft (200). The operator can mount the first inner ring (310) to the motor shaft (200) through the adjustment portion (311), and at this time, the mounting position of the first inner ring (310) can be adjusted so that an appropriate preload is applied to the rolling element (500).

[0055] In this way, the first inner ring (310) according to the embodiment of the present invention has the adjustment part (311) and the contact part (313) formed integrally, thereby enabling it to simultaneously perform the function of a nut member for applying a conventional preload and the function of a conventional inner ring. Accordingly, the first inner ring (310) according to the embodiment of the present invention can directly apply a preload to the rolling element (500) while in contact with the rolling element (500).

[0056] Accordingly, according to an embodiment of the present invention, compared to a structure in which axial force is transmitted in multiple stages through a conventional nut member and a washer member, the loss of axial force when applying preload can be reduced and the dispersion of axial force can be minimized, so that preload can be applied more stably to the rolling element (500).

[0057] By using the present invention, the stability, reliability, and quality improvement of the bearing assembly (100) can be achieved. In addition, by using the present invention, there is no need to assemble the nut member and washer member separately, so costs can be reduced and installation can be performed smoothly even in confined spaces.

[0058] Meanwhile, the first inner ring (310) may further include a plurality of adjustment protrusions (312) that are formed to protrude radially from the outer surface of the adjustment part (311) and are spaced apart in the circumferential direction of the adjustment part (311).

[0059] For example, a plurality of adjustment protrusions (312) may be formed on the outer surface of the adjustment part (311) at equal intervals. However, the number and shape of the adjustment protrusions (312) are not limited to the illustrated embodiment and may be modified to have various numbers and shapes. When mounting the first inner ring (310) to the motor shaft (200), the adjustment protrusions (312) may make it easier to attach a mounting mechanism to the adjustment part (311) or for an operator to grip the adjustment part (311).

[0060] If the first inner ring (310) according to an embodiment of the present invention can be fixed in position while in close contact with the motor shaft (200), it can be mounted on the motor shaft (200) in various ways.

[0061] For example, the first inner ring (310) can be press-fitted and fixed to the outer surface of the motor shaft (200).

[0062] Specifically, the inner diameter of the first inner ring (310) can be formed to correspond to the outer diameter of the motor shaft (200). The first inner ring (310) can be fitted onto the motor shaft (200) and press-fitted to the outer surface of the motor shaft (200) by means of an interference fit method. At this time, an axial force may be generated in the first inner ring (310) by the press-fitting of the first inner ring (310), and thereby a preload may be applied to the rolling element (500).

[0063] When the first inner ring (310) is press-fitted and fixed to the motor shaft (200), the process of machining screw threads on the motor shaft (200) and the first inner ring (310) is omitted, thereby reducing machining costs and shortening the time required to mount the first inner ring (310).

[0064] In another embodiment, the first inner ring (310) may be screw-coupled to the outer surface of the motor shaft (200). Specifically, a first screw thread may be formed on the outer surface of the motor shaft (200), and a second screw thread may be formed on the inner surface facing the motor shaft (200) to correspond to the first screw thread so that the first inner ring (310) is screw-coupled to the motor shaft (200).

[0065] The first inner ring (310) can be fixed to the motor shaft (200) by screwing the second thread to the first thread, and at the same time, a fastening torque can be generated. An axial force can be generated in the first inner ring (310) by the fastening torque, and thereby a preload can be applied to the rolling element (500). At this time, the torque can be measured and adjusted so that an appropriate amount of preload is applied to the rolling element (500).

[0066] Meanwhile, referring to FIGS. 3 to 8, the first inner ring (310) may include an oil supply groove (315). The oil supply groove (315) may be formed to be recessed to guide the supplied lubricant into the space between the outer ring portion (400) and the inner ring portion (300). The oil supply groove (315) may form a passage for supplying lubricant to the rolling element (500).

[0067] Specifically, the oil supply groove (315) may include a first flow groove (316). The first flow groove (316) may be formed continuously from the upper surface of the first inner ring (310) along the outer surface of the first inner ring (310) to form a first oil passage for supplying lubricant to the rolling element (500).

[0068] For example, the first flow groove (316) may include an upper groove formed on the upper surface of the first inner ring (310) and an outer groove formed on the outer surface of the first inner ring (310) and communicating with the upper groove. The first oil passage may be formed by the upper groove and the outer groove. The lubricant supplied to the motor shaft (200) may be supplied to the rolling element (500) through the first oil passage.

[0069] Here, the first flow grooves (316) are formed spaced apart in the circumferential direction of the first inner ring (310) and may be arranged between adjacent control protrusions (312). However, the arrangement of the first flow grooves (316) and control protrusions (312) is not limited to the above and can be varied in many ways.

[0070] Additionally, the oil supply groove (315) may include a second flow groove (317). The second flow groove (317) may be formed continuously along the inner surface of the first inner ring (310) from the lower surface of the first inner ring (310) to form a second oil passage for supplying lubricant to the rolling element (500).

[0071] For example, the second flow groove (317) may include an inner groove formed on the inner surface of the first inner ring (310) and a lower groove formed on the lower surface of the first inner ring (310) and communicating with the inner groove. The second oil passage may be formed by the inner groove and the lower groove. The lubricant supplied to the motor shaft (200) may be supplied to the rolling element (500) through the second oil passage.

[0072] The second flow groove (317) is formed in a plurality of spaced-apart locations along the circumferential direction of the first inner ring (310), and may be formed at a position corresponding to the control projection (312) on the inner surface of the first inner ring (310). However, the arrangement of the second flow groove (317) and the control projection (312) is not limited to the above and can be varied in various ways.

[0073] Additionally, for example, the present invention may further include a retainer member (530) provided between the inner ring portion (300) and the outer ring portion (400) for mounting a rolling element (500). The retainer member (530) may include a first retainer on which a first rolling element (510) is mounted and a second retainer on which a second rolling element (520) is mounted. The first retainer and the second retainer may be installed at a predetermined distance apart. Lubricant supplied to the first oil passage or the second oil passage may be supplied to the space between the outer ring portion (400) and the rolling element (500) through the space between the first retainer and the second retainer. By doing so, the lubrication performance of the bearing assembly (100) may be further improved. However, the mounting structure of the rolling element (500) and the shape of the retainer are not limited to those described above and may be modified in various ways.

[0075] Meanwhile, a bearing assembly (100) according to an embodiment of the present invention is described below. The bearing assembly (100) according to an embodiment of the present invention may include a configuration included in the in-wheel drive device (10) described above, and redundant descriptions of the same configuration are omitted below.

[0076] A bearing assembly (100) according to an embodiment of the present invention includes a motor part (not shown) and a bearing assembly (100).

[0077] A bearing assembly (100) is mounted on the radial outer surface of the central axis of a motor shaft (200) and includes an inner ring portion (300) comprising a first inner ring (310) and a second inner ring (320) arranged along the central axis, an outer ring portion (400) mounted radially outwardly spaced from the inner ring portion (300), and a rolling element (500) provided between the inner ring portion (300) and the outer ring portion (400).

[0078] Here, the first inner ring (310) is inserted into the space between the motor shaft (200) and the rolling element (500) to apply preload to the rolling element (500).

[0080] Meanwhile, a method for manufacturing a bearing assembly (100) according to an embodiment of the present invention will be described below. The method for manufacturing a bearing assembly (100) according to an embodiment of the present invention is for manufacturing the bearing assembly (100) described above, and redundant descriptions of identical components will be omitted below.

[0081] A method for manufacturing a bearing assembly (100) according to an embodiment of the present invention includes a first step and a second step.

[0082] The first step is to mount a second inner ring (320), an outer ring portion (400) spaced apart from the radial outer side of the second inner ring (320), and a rolling element (500) provided between the second inner ring (320) and the outer ring portion (400) on the radial outer surface of the central axis of the motor shaft (200).

[0083] Specifically, in the first step, the second inner ring (320), the rolling element (500), and the outer ring part (400) can be mounted on the motor shaft (200) in an assembled state. At this time, the second inner ring (320) can be pressed into the outer surface of the motor shaft (200).

[0084] The second step is to insert a first inner ring (310) into the space between the motor shaft (200) and the rolling element (500), and to fix the first inner ring (310) to the motor shaft (200) so that a preset preload is applied to the rolling element (500).

[0085] Specifically, in the second step, the first inner ring (310) can be fixed to the motor shaft (200) by press-fitting or screw fastening. When the first inner ring (310) is fixed to the motor shaft (200), an axial force may be generated in the first inner ring (310), and thereby a preload may be applied to the rolling element (500).

[0086] The first inner ring (310) may include a contact portion (313) and a control portion (311) extending in the direction of the central axis from the contact portion (313).

[0087] And the second step can be performed such that the contact portion (313) is inserted into the radial inner side of the outer ring portion (400) and contacts the rolling element (500), and the adjustment portion (311) is exposed to the outside of the outer ring portion (400) in the direction of the central axis.

[0088] Accordingly, in the second stage, the first inner ring (310) can be fixed to the motor shaft (200) using the adjustment unit (311), and at the same time, an appropriate preload can be applied to the rolling element (500).

[0089] As such, the first inner ring according to the embodiment of the present invention has a control portion and a contact portion formed integrally, thereby enabling it to simultaneously perform the function of a conventional inner ring and the function of a nut member that fixes the inner ring and applies preload. Accordingly, the first inner ring according to the embodiment of the present invention can directly apply preload to the rolling element while in contact with the rolling element.

[0090] Accordingly, according to an embodiment of the present invention, compared to a structure in which axial force is transmitted in multiple stages through a conventional nut member and a washer member, the loss of axial force can be reduced and the dispersion of axial force can be minimized, thereby allowing preload to be applied more stably to the rolling element. By utilizing the present invention, the stability, reliability, and quality improvement of the bearing assembly can be realized.

[0091] Although specific embodiments of the present invention have been described above, the spirit and scope of the present invention are not limited to these specific embodiments, and various modifications and variations are possible by those skilled in the art without altering the gist of the invention as described in the claims. Explanation of the symbols

[0092] 10: In-wheel drive unit 100: Bearing assembly. 200: Motor shaft 210: Shaft part 220: Flange section 300: Inner ring section 310: 1st inner ring 311: Adjustment part 312: Adjustment projection 313: Contact part 315: Oil supply groove 316: First flow groove 317: Second fluid groove 320: Second inner ring 400: Outer ring 500: Rolling element 510: 1st rolling element 520: 2nd rolling element 530: Retainer absence

Claims

Claim 1 An in-wheel drive device comprising: a motor shaft; an inner ring portion including a first inner ring and a second inner ring mounted on the radial outer surface of the central axis of the motor shaft and arranged along the central axis; an outer ring portion mounted spaced outwardly from the inner ring portion in the radial direction; and a rolling element provided between the inner ring portion and the outer ring portion, wherein the first inner ring is inserted into the space between the motor shaft and the rolling element and fixed to the motor shaft, and is arranged to be in direct contact with the rolling element to apply preload to the rolling element. Claim 2 An in-wheel drive device according to claim 1, wherein the motor shaft is provided in the direction of the central axis and the inner ring portion is fitted therein; and a flange portion protruding radially from the shaft portion, provided to face the first inner ring with the second inner ring in between, and provided to support the second inner ring. Claim 3 In claim 1, the first inner ring comprises: a contact portion provided on the radial inner side of the outer ring portion and configured to contact the rolling element; and a control portion extending from the contact portion in the direction of the central axis and configured to be exposed to the outside of the outer ring portion in the direction of the central axis, thereby forming an in-wheel drive device. Claim 4 In paragraph 3, the first inner ring further comprises a plurality of adjustment protrusions formed to protrude radially from the outer surface of the adjustment part and spaced apart in the circumferential direction of the adjustment part. Claim 5 In claim 1, the first inner ring is an in-wheel drive device that is press-fitted and fixed to the outer surface of the motor shaft. Claim 6 In paragraph 3, an in-wheel drive device having a first screw thread formed on the outer surface of the motor shaft, and a second screw thread formed on the inner surface facing the motor shaft so as to correspond to the first screw thread so as to be screw-coupled to the motor shaft. Claim 7 In claim 4, the first inner ring is an in-wheel drive device comprising an oil supply groove formed to be recessed to guide the supplied lubricant into the space between the outer ring portion and the inner ring portion. Claim 8 In claim 7, the oil supply groove is formed continuously from the upper surface of the first inner ring along the outer surface of the first inner ring to form a first flow groove for supplying lubricant to the rolling element, in a wheel drive device. Claim 9 In claim 8, the first flow groove is formed spaced apart in the circumferential direction of the first inner ring, and is an in-wheel drive device disposed between adjacent adjustment protrusions. Claim 10 In claim 7, the oil supply groove is formed continuously along the inner surface of the first inner ring from the lower surface of the first inner ring to form a second flow groove for supplying lubricant to the rolling element, in a wheel drive device. Claim 11 In item 10, the second flow groove is formed spaced apart in the circumferential direction of the first inner ring, and is formed at a position corresponding to the adjustment projection on the inner surface of the first inner ring in an in-wheel drive device. Claim 12 In claim 1, the in-wheel drive device comprises: a first rolling element provided between the first inner ring and the outer ring portion; and a second rolling element provided between the second inner ring and the outer ring portion and spaced apart from the first rolling element in the direction of the central axis. Claim 13 A bearing assembly comprising: an inner ring portion including a first inner ring and a second inner ring that are mounted on the radially outer surface of the central axis of a motor shaft and arranged along the central axis; an outer ring portion mounted spaced apart from the inner ring portion in the radial direction; and a rolling element provided between the inner ring portion and the outer ring portion, wherein the first inner ring is inserted into the space between the motor shaft and the rolling element and fixed to the motor shaft, and is arranged to be in direct contact with the rolling element to apply a preload to the rolling element. Claim 14 A method for manufacturing a bearing assembly comprising: a first step of mounting a second inner ring, an outer ring portion spaced radially outward from the second inner ring, and a rolling element provided between the second inner ring and the outer ring portion on the radial outer surface of the central axis of a motor shaft; and a second step of inserting a first inner ring into the space between the motor shaft and the rolling element, and fixing the first inner ring to the motor shaft so that the first inner ring is positioned to come into direct contact with the rolling element, thereby applying a preset preload to the rolling element. Claim 15 A method for manufacturing a bearing assembly according to claim 14, wherein the first inner ring comprises a contact portion and a control portion extending from the contact portion in the direction of the central axis, and the second step is performed such that the contact portion is inserted into the radially inner side of the outer ring portion to contact the rolling element, and the control portion is exposed to the outside of the outer ring portion in the direction of the central axis.

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