CN221162967U

CN221162967U - Worm support structure and electric steering mechanism

Info

Publication number: CN221162967U
Application number: CN202322864971.8U
Authority: CN
Inventors: 张瑞; 刘鹏
Original assignee: Bosch Automotive Steering Jinan Co Ltd
Current assignee: Bosch Automotive Steering Jinan Co Ltd
Priority date: 2023-10-24
Filing date: 2023-10-24
Publication date: 2024-06-18
Anticipated expiration: 2033-10-24

Abstract

The utility model provides a worm support structure and an electric steering mechanism, wherein the worm support structure can be used for the electric steering mechanism of a vehicle, and comprises a worm, a needle bearing and a shell, wherein the worm is supported on the shell through the needle bearing, the worm is provided with a rod body and a raceway part which is constructed on the outer periphery of the rod body and extends along the axial direction, a raceway for circulating balls is constructed in the raceway part, the worm support structure further comprises a support piece, and the end face of the raceway part of the worm in the axial direction is abutted against the support piece and then abutted against the needle bearing.

Description

Worm support structure and electric steering mechanism

[ Field of technology ]

The utility model relates to the technical field of transmission mechanism arrangement of an electric steering mechanism, in particular to a worm support structure of the electric steering mechanism and the electric steering mechanism.

[ Background Art ]

With the popularity of electric vehicles and vehicle electronic systems, pure electric steering mechanisms are increasingly being used in vehicles, especially electric vehicles, instead of hydraulic power steering mechanisms. Compared with the traditional hydraulic power steering mechanism, the pure electric steering mechanism has the advantages of compact structure, rapid response, high steering stability and the like.

In many of the existing hydraulic power steering systems for commercial vehicles, recirculating ball steering systems are used, in which a worm is used as the drive for the steering system. In the hydraulic power-assisted steering mechanism, torque is input through a torque input shaft to a worm, then the worm rotates to drive a circulating ball on the worm to roll, the circulating ball drives a piston to translate, and the piston drives a sector shaft to rotate through a gear rack, so that steering torque is output. During the torque transmission, the worm is subjected to a reaction force in the axial direction, and if the worm is not fixedly supported in the axial direction, the worm is displaced in the axial direction. Therefore, a worm support structure is generally configured in such a hydraulic power steering mechanism to support the worm.

Referring to fig. 1, there is shown a schematic structural view of a worm support structure 100 of a known hydraulic power steering mechanism. The hydraulic power steering mechanism is generally suitable for use with heavy vehicles. The worm support structure 100 in fig. 1 includes a worm 110, a needle bearing 120, and a housing 130, and the worm 110 is supported on both ends by the needle bearing 120 on the housing 130, thereby achieving axial fixation thereof. Referring to fig. 2 and 3, there are shown enlarged views of the worm support structure according to fig. 1 at the right and left ends of the worm, respectively. As can be seen from fig. 2 and 3, in the worm support structure 100 of fig. 1, the worm 110 is directly supported on the needle bearings 120 with its left and right ends, respectively. A washer 140 is disposed between the needle bearing 120 and the housing 130. In such a hydraulic power steering mechanism, because of the hydraulic power applied during operation, the worm 100 is required to bear a smaller axial load, so that the needle bearing 120 is also required to be smaller, and a sufficient needle bearing support surface can be provided directly through the end of the worm 100.

For electric power steering mechanisms that also use a worm as the transmission, the axial load that the worm bears is generally greater than in hydraulic power steering mechanisms, and in particular for electric power steering mechanisms for heavy vehicles, the steering torque that the worm needs to output generally needs to exceed 8000Nm, so that the axial load that the worm needs to bear is also greater, up to 150kN, and thus the needle bearing that is required is also greater, in a manner that directly supports the end of the worm on the needle bearing is insufficient to ensure axial support of the worm.

[ utility model ]

According to a different aspect, one of the purposes of the present utility model is to ensure axial support of the worm when it is required to carry a large axial load.

In addition, the utility model aims to solve or alleviate other technical problems in the prior art.

According to an aspect of the present utility model, there is provided:

The utility model provides a worm bearing structure, it includes worm, bearing and casing that can be used to electric steering mechanism of vehicle, the worm passes through bearing support on the casing, the worm has the body of rod and constructs on the outer periphery of the body of rod and along the raceway portion that extends of axial direction, is constructed in the raceway portion and is used for circulating the ball, wherein, worm bearing structure still includes support piece, the terminal surface of raceway portion of worm in the axial direction is supported against on the support piece, and then is supported against bearing.

According to another aspect of the present utility model, there is provided an electric power steering mechanism for a vehicle, wherein the electric power steering mechanism includes an electric control unit input shaft connected to an end of the worm and inputting a driving torque thereto to rotate the worm, a recirculating ball disposed in the raceway and driven by the rotational movement of the worm to roll along the raceway, and the worm support structure described above.

[ Description of the drawings ]

The above and other features of the present utility model will become apparent with reference to the accompanying drawings, in which,

FIG. 1 shows a schematic structural view of a worm support structure of a known hydraulic power steering mechanism;

fig. 2 shows an enlarged view of the worm support structure according to fig. 1 at the right end of the worm;

fig. 3 shows an enlarged view of the worm support structure according to fig. 1 at the left end of the worm;

FIG. 4 shows a schematic structural view of a proposed worm support structure according to one embodiment of the utility model;

fig. 5 shows an enlarged view of the worm support structure according to fig. 4 at the right end of the worm;

fig. 6 shows an enlarged view of the worm support structure according to fig. 4 at the left end of the worm.

[ Detailed description ] of the invention

It is to be understood that, according to the technical solution of the present utility model, those skilled in the art may propose various alternative structural modes and implementation modes without changing the true spirit of the present utility model. Accordingly, the following detailed description and drawings are merely illustrative of the utility model and are not intended to be exhaustive or to limit the utility model to the precise form disclosed.

Terms of orientation such as up, down, left, right, front, rear, front, back, top, bottom, etc. mentioned or possible to be mentioned in the present specification are defined with respect to the configurations shown in the drawings, which are relative concepts, and thus may be changed according to different positions and different use states thereof. These and other directional terms should not be construed as limiting terms. Furthermore, the terms "first," "second," "third," and the like are used for descriptive and distinguishing purposes only and are not to be construed as indicating or implying a relative importance of the corresponding components or a sequential or assembly order of the components.

Referring to fig. 4, a schematic structural view of a worm support structure 200 according to one embodiment of the present utility model is shown. The worm support structure 200 may be used in an electric steering mechanism for a vehicle, such as an electric steering mechanism for a heavy-duty commercial vehicle. The worm support structure 200 includes a worm 210, a needle bearing 220, and a housing 230. The worm 210 is used as a transmission member in the electric power steering mechanism, receives driving torque input from the input shaft of the electric control unit, and drives the recirculating ball mounted thereon to roll, thereby converting rotational movement of the input shaft of the electric control unit into rolling movement of the recirculating ball. The worm 210 is supported on the housing 230 by a needle bearing 220 to prevent the axial load to which the worm 210 is subjected from displacing the worm 210 in the axial direction. The worm 210 has a rod body 211 and a raceway portion 212 which is formed on an outer peripheral edge of the rod body 211 and extends in an axial direction, and a raceway for circulating a ball is formed in the raceway portion 212. As the worm 210 rotates, the recirculating ball rolls along the raceway. A support 240 is provided between the end of the raceway portion 212 of the worm 210 in the axial direction and the needle bearing 220, so that the end of the raceway portion 212 is abutted against the support 240 and thus the needle bearing 220.

According to this embodiment of the utility model, the worm 210 is no longer directly supported by its end against and on the needle bearing 220 as in the known structure, but with the end of the raceway 212 against the support 240, thereby indirectly supporting on the needle bearing 220. The bearing surface against and bearing on the needle bearing 220 is thus no longer the end face of the worm in the known construction, but the contact surface of the support 240 with the needle bearing 220. The support surface can be designed to be larger than the end surface area of the worm 210, so that the bearing of larger axial load can be realized, and when the support surface 240 fails or is damaged, the whole worm 210 does not need to be replaced, only the support piece 240 needs to be replaced, and the maintenance cost is reduced.

Referring to fig. 5 and 6, there are shown enlarged views of the worm support structure according to fig. 4 at the right and left ends of the worm, respectively. In the embodiment according to fig. 5, the support 240 is configured as a spacer structure which is fitted over the rod body 211 and which has an annular first end face 241 and a second end face 242, the first end face 241 bearing against the end face of the raceway 212 and the second end face 242 bearing against the needle bearing 220. The second end face 242 has an area greater than that of the first end face 241. By this construction of the support 240, it is achieved that the area of the support surface supported on the needle bearing 220 is greater than the area of the worm 210 supported on the support 240, and that the worm 210 is in fact supported on the needle bearing 220 via the second end face 242, which can take up a large axial load.

In one embodiment of the present utility model, the first end surface 241 is connected to the second end surface 242 by a first connecting surface 243 and a second connecting surface 244 adjacent to each other, the first connecting surface 243 being configured as a tapered curved surface that is smooth and curved toward the worm 210, and the second connecting surface 244 being configured as a cylindrical curved surface coaxial with the worm 210. The shape of the connection surface of the first end surface 241 and the second end surface 242 of the gasket affects the load bearing properties of the gasket. In this embodiment, particularly, the first connection surface 243 is configured as a smooth conical curved surface bent toward the worm 210, which can make the strength of the gasket as a whole higher when supported, make the gasket less deformable and have a longer service life, and also can prevent damage and cracking of the gasket to a great extent.

In one embodiment of the present utility model, the area of the first end surface 241 is equal to or larger than the area of the end surface of the track portion 212; the area of the second end face 242 is equal to or greater than the area of the needle envelope surface of the needle bearing 220. This way of constructing the spacer is mainly to enable the spacer itself to more uniformly carry the axial load, and if the areas of the first end face 241 and the second end face 242 of the spacer are too small, that is, the area of the first end face 241 is smaller than the area of the end face of the raceway portion 212, or the area of the second end face 242 is smaller than the area of the needle envelope surface of the needle bearing 220, stress concentration on the end face of the raceway portion 212 and the needle envelope surface of the needle bearing 220 may be caused, thereby causing damage to the surfaces of the worm 210 and the needle bearing 220. The first end face 241 and the second end face 242 are both configured in a larger manner, so that the stress generated by the axial load is concentrated to the gasket, the strength of the gasket is higher, and the replacement is convenient, thereby reducing the maintenance cost of the worm support structure 100.

In one embodiment of the utility model, the gasket is made of hardenable steel. The hardenable steel has the advantages of good shock resistance, high surface hardness, good wear resistance, fatigue resistance and good impact resistance, and the gasket manufactured by the hardenable steel has higher fatigue strength and longer service life when bearing axial load.

In one embodiment of the present utility model, the raceway portion 212 has planar annular end faces 2121, 2122 at both ends thereof, respectively, and the worm 210 is supported on the needle bearing 220 with the two annular end faces 2121, 2122, respectively, via the support 240. That is, the raceway portion 212 does not extend over the entire axial direction length of the rod body 211. It should be understood that, when the worm is initially molded, the raceway portion 212 extends over the entire axial length of the rod body 211, and the rod body 211 and the raceway portion 212 are integrally molded. However, in this embodiment, the worm is machined, and at both ends of the worm 210, the raceway portions 212 are turned with a part of the material in the circumferential direction, that is, the raceway portions at the outer circumferential edges of both ends of the worm 211 are removed when the worm is initially formed, so that the worm herein also forms the rod body 211. Thus, the diameter at the end of the worm 210 (i.e., the diameter of the rod body 211) is smaller than the diameter of the raceway portion 212, and the end face of the raceway portion 212 is no longer on the same plane as the end face of the worm 210 (i.e., the end face of the rod body 211), but annular end faces 2121, 2122 are formed. The worm 210 in this embodiment has portions of the raceway portions removed at both ends thereof, as compared with the worm in the known structure, so that the worm 210 can be abutted against the washers by the two annular end faces 2121, 2122 of the raceway portions 212, respectively, to be supported against the two needle bearings 220, respectively. The structure in which part of the raceway portions are removed at the two ends of the worm 210 can also reduce the weight of parts of the worm 210, thereby reducing the weight of the whole electric steering mechanism and contributing to the reduction of the energy consumption of the whole electric steering mechanism.

In one embodiment of the utility model, the distance from one annular end face 2121 to the end 213 of the worm 210 adjacent thereto is the same as the distance from the other annular end face 2122 to the end 214 of the worm 210 adjacent thereto. That is, the worm screw at the time of initial molding removes the same axial length of material at both ends thereof, forming the raceway portion 212 in this embodiment. At this time, the rod body 211 and the raceway portion 212 constructed thereon form a completely symmetrical structure, which not only enables to omit a separate finishing process during the machining of the raceway portion 212, thereby saving the machining time, but also saves the step of error proofing during the assembly, thereby saving the assembly time of the worm 210.

In one embodiment of the present utility model, a washer 250 is configured between the needle bearing 220 and the housing 230, and the needle bearing 220 is supported against the housing 230 by the washer 250. An annular thickened washer is typically employed between the needle bearing 220 and the housing 230 to disperse the pressure of the needle bearing 220 against the housing 230 and prevent damage to the housing 230.

In one embodiment of the present utility model, both ends of the worm 210, i.e., the rod body 211, penetrate into the outer wall of the housing 230 through the support 240, the needle bearing 220, and the washer 250. That is, in addition to being supported to the housing 230 by the support 240 for axial fixation, both ends of the worm 210 also protrude into the outer wall of the housing 230, whereby a certain radial load can be carried, and radial fixation is achieved.

Another aspect of the present utility model also proposes an electric steering mechanism comprising an electric control unit input shaft, a recirculating ball and the above-mentioned worm support structure 200. An input shaft of the electronic control unit is connected to an end of the worm 210 and inputs driving torque thereto to rotate the worm, and the circulating ball is disposed in the raceway and is driven by the rotational movement of the worm 210 to roll along the raceway.

It should be appreciated that the electric steering mechanism of the present utility model may be mounted on a variety of vehicles, including cars, vans, buses, electric vehicles, hybrid vehicles, and the like.

It should be understood that all of the above preferred embodiments are exemplary and not limiting, and that various modifications or variations of the above-described specific embodiments, which are within the spirit of the utility model, should be made by those skilled in the art within the legal scope of the utility model.

Claims

1. A worm support structure (200) usable in an electric power steering mechanism of a vehicle, comprising a worm (210), a needle bearing (220) and a housing (230), the worm (210) being supported on the housing (230) by the needle bearing (220), the worm (210) having a rod body (211) and a raceway portion (212) configured on an outer peripheral edge of the rod body (211) and extending in an axial direction, a raceway for circulating a ball being configured in the raceway portion (212), characterized in that the worm support structure (200) further comprises a support (240), an end face of the raceway portion (212) of the worm (210) in an axial direction being abutted against the support (240) and thereby being abutted against the needle bearing (220).

2. The worm support structure (200) according to claim 1, characterized in that the support (240) is configured as a spacer which is fitted over the rod body (211) and has a ring-shaped first end face (241) and a second end face (242) opposite to the first end face (241), the first end face (241) being abutted against the end face of the raceway portion (212), the second end face (242) being abutted against the needle bearing (220), and the area of the second end face (242) being larger than the area of the first end face (241).

3. The worm support structure (200) according to claim 2, characterized in that the first end face (241) is connected to the second end face (242) by a first connection face (243) and a second connection face (244) that are adjacent to each other, the first connection face (243) being configured as a conical curved surface that is smooth and curved towards the worm (210), the second connection face (244) being configured as a cylindrical curved surface coaxial with the worm (210).

4. The worm support structure (200) according to claim 2, wherein the area of the first end surface (241) is equal to or larger than the area of the end surface of the raceway portion (212), and the area of the second end surface (242) is equal to or larger than the area of the needle envelope surface of the needle bearing (220).

5. The worm support structure (200) of claim 2, wherein the shim is made of hardenable steel.

6. The worm support structure (200) according to claim 2, wherein the raceway portion (212) has planar annular end faces at both ends thereof, respectively, and the worm (210) abuts on the spacer with the two annular end faces, respectively.

7. The worm support structure (200) of claim 6, wherein a distance from one of the annular end faces to an end of the worm (210) adjacent thereto is the same as a distance from another of the annular end faces to an end of the worm (210) adjacent thereto.

8. The worm support structure (200) according to any one of claims 1 to 7, characterized in that a washer (250) is configured between the needle bearing (220) and the housing (230), the needle bearing (220) being abutted against the housing (230) by the washer (250).

9. The worm support structure (200) of claim 8, wherein both ends of the rod body (211) penetrate into an outer wall of the housing (230) through the support (240), the needle bearing (220) and the washer (250).

10. An electric steering mechanism for a vehicle, characterized by comprising an electric control unit input shaft connected to an end of the worm (210) and inputting a driving torque thereto to rotate, a recirculating ball disposed in the raceway and driven by the rotational movement of the worm (210) to roll along the raceway, and a worm support structure (200) according to any one of claims 1 to 9.