CN107640209B

CN107640209B - Steering column

Info

Publication number: CN107640209B
Application number: CN201610581390.5A
Authority: CN
Inventors: 董雪飞; 高玫; 刘云; 高明; 赵鑫日; 张辰晟; 张成一; 任斌
Original assignee: Robert Bosch Automotive Steering GmbH
Current assignee: Robert Bosch Automotive Steering System Co Ltd
Priority date: 2016-07-22
Filing date: 2016-07-22
Publication date: 2021-10-26
Anticipated expiration: 2036-07-22
Also published as: CN107640209A

Abstract

A steering column is disclosed in which an injection molded bushing is installed in a gap between an outer tube and an inner tube. The outer peripheral surface of the bush is provided with a plurality of convex strips and a plurality of guide parts, the guide parts are positioned between the convex strips and the inner connecting end, and the radial height of the guide parts is gradually increased from the position of the guide parts close to the inner connecting end to the direction of the convex strips closest to the guide parts. The ratio of the axial length of the guide portion to the radial height thereof is not less than 0.5 and not more than 1.8. The inner peripheral surface of the bush contacts the inner pipe, the raised strips contact the inner wall of the outer pipe in an interference fit mode, and the outer peripheral surface faces the inner wall at intervals in the radial direction. The steering column is easy to manufacture and the collapsing force is easy to meet the requirement.

Description

Steering column

Technical Field

The present application relates to a steering system for a vehicle, and more particularly to a collapsible steering column.

Background

When the automobile collides, the driver always rushes forward because the automobile stops moving suddenly, and the chest of the human body collides with the steering wheel. The collapsible steering column can collapse and deform according to the pre-design, and the damage caused by the impact of the steering column on the chest of a driver is reduced. At present, some collapsible steering columns adopt a squeeze riveting point or a convex rib mode to realize collapse energy absorption, and some inner and outer tubes adopt a bush in interference fit to realize collapse energy absorption, but the modes are sensitive to the processing and manufacturing tolerance of the column tube, have high requirement on the tolerance and are not easy to control the collapse energy to a proper range.

Accordingly, there is a need for improvement to overcome the technical problems in the prior art.

Disclosure of Invention

The application mainly aims to solve the problem that the collapse force of the steering column is difficult to control.

In order to solve the above technical problem, the present application provides a steering column, which includes:

an inner tube having an inner connection end at one axial end;

an outer tube having an outer connecting end at one axial end, the outer connecting end of the outer tube being coaxially sleeved outside the inner tube in an axial direction through the inner connecting end with a radial gap therebetween to allow mutual movement thereof in a direction to shorten an axial length of the steering column; and

the injection-molded bushing is installed in the gap and comprises a cylindrical body, the body is provided with an inner circumferential surface and an outer circumferential surface which are opposite in the radial direction, the inner circumferential surface is contacted with the inner pipe, the outer circumferential surface of the bushing is provided with a plurality of convex strips and a plurality of guide portions, the convex strips are contacted with the inner wall of the outer pipe in an interference fit mode, the outer circumferential surface faces the inner wall in the radial direction at intervals, the guide portions are located between the convex strips and the inner connecting end, the radial height of the guide portions is gradually increased from the positions, close to the inner connecting end, of the guide portions to the direction, closest to the convex strips, of the guide portions, and the ratio of the axial length of the guide portions to the radial height of the guide portions is not less than 0.5 and not more than 1.8.

Because the outer peripheral surface of the bush has a specially configured guide portion, when the outer pipe is mounted to the bush on the inner pipe, the outer pipe can be mounted in place while maintaining a preferred degree of coaxiality. Before the bushing is installed in the outer pipe, the radial height of the convex strips relative to the outer peripheral surface is larger than the gap between the inner pipe and the outer pipe, and the outer pipe can remove the allowance at the tops of the convex strips, so that the bushing has proper interference in the gap between the outer pipe and the inner pipe, and proper collapse force is obtained. Therefore, the steering column is easy to manufacture and the collapse force is easy to meet the requirement.

Drawings

The present application will be more fully understood by reference to the following detailed description of specific embodiments in conjunction with the accompanying drawings. Wherein:

FIG. 1 shows an exploded schematic view of a steering column according to one embodiment of the present application;

FIG. 2 shows a schematic cross-sectional view of a steering column in which a steering rod connected to a steering wheel (not shown) is also mounted;

FIG. 3 shows a schematic view of a bushing; and

fig. 4 shows an enlarged partial cross-sectional view of the steering column.

Detailed Description

A specific embodiment of the present application is described in detail below with reference to fig. 1 to 4.

The steering column 100 includes an inner tube 1, an outer tube 2, and a bushing 3 therebetween. Fig. 2 shows a schematic cross-sectional view in which the steering column 100 is further equipped with a steering rod 8 connected to a steering wheel (not shown).

The inner pipe 1 and the outer pipe 2 are hollow pipes which are axially through, one of two axial ends of the inner pipe 1 is an inner connecting end 10, and one of two axial ends of the outer pipe 2 is an outer connecting end 20. The outer connecting end 20 of the outer tube 2 is coaxially sleeved outside the inner tube 1 in the axial direction through the inner connecting end 10, and a radial gap is left between the outer tube 2 and the inner tube 1 to allow the two to move relative to each other in a direction to shorten the axial length of the steering column 100.

The bush 3 is formed by injection molding, and is fitted in the gap between the outer pipe 2 and the inner pipe 1. The bush 3 has a cylindrical body 30, and the body 30 has an inner peripheral surface 31 and an outer peripheral surface 32 which are diametrically opposed to each other. That is, the inner wall of the body 30 is an inner peripheral surface 31, and the outer wall of the barrel is an outer peripheral surface 32. The inner peripheral surface 31 contacts the inner pipe 1, and the outer peripheral surface 32 of the bush 3 has a plurality of ridges 33 and a plurality of guide portions 34 formed integrally therewith. As shown in the figure, the bush 3 is provided with three circles of raised strips 33 at intervals in the axial direction, and the number of two circles close to the two ends in the axial direction is larger, at least 6, for example, 8 in each; the number of the middle circles is relatively small, and is not more than 6, for example, 4. The ribs 33 in each turn are equally spaced. The guiding portion 34 is located between the protruding strip 33 and the inner connection end 10. For example, the guide portion 34 is integrally formed in front of the convex strip 33, and the guide portion 34 is connected to the convex strip 33 with no space in the axial direction. The outer tube 2 will contact the guide 34 and then the rib 33 when mounted. The guide portion 34 gradually increases in radial height from a position thereof near the inner connection end 10 toward the closest projection 33. The ribs 33 contact the inner wall 21 of the outer tube 2 with an interference fit, and the outer peripheral surface 32 faces the inner wall 21 with a radial spacing. The radial height refers to the radial dimension of the guide portion 34 relative to the outer peripheral surface 32. In a particular embodiment, the ratio of the axial length of the guide 34 to its radial height is not less than 0.5 and not more than 1.8; possibly, the ratio is not less than 0.8; it is feasible that the ratio is not more than 1.

In the particular embodiment shown, the body 30 is circumferentially discontinuous, that is, the body 30 is an open-ring cylindrical shape. When mounting, if the inner diameter of the body 30 is slightly smaller than the outer diameter of the inner tube 1, the open-ring cylindrical body 30 can be freely opened without generating a large tension, and thus can be easily mounted to the outside of the inner tube 1. If the inner diameter of the body 30 is slightly larger than the outer diameter of the inner pipe 1, the body 30 can be freely contracted by the pressing of the inner wall 21 of the outer pipe 2 against the convex strips 33, so that the inner peripheral surface is in close contact with the inner pipe 1. Therefore, the scheme allows for relatively large errors and is easy to manufacture.

The bush 3 has axially opposite first and

second ends

36, 38, the inner peripheral surface 31 of the first end 36 having an inwardly projecting inner flange 37, the inner flange 37 contacting the inner connecting end 10 of the inner tube 1. The outer peripheral surface 32 of the second end 38 has an outwardly projecting outer flange 39. The outer flange 39 has a radial height relative to the outer peripheral surface 32 that is greater than the gap between the inner and

outer tubes

1, 2, so that the outer flange 37 blocks axial movement of the outer tube 2 when the outer connecting end 20 of the outer tube 2 is brought towards the second end 38 of the liner 3. In a possible embodiment, the outer tube 2 has an axial distance from the outer flange 39, which may be no greater than 15 mm, or no greater than 10 mm, or no greater than 5 mm, or no less than 1 mm.

The liner 3 is also provided with a break 45, the break 45 being located between the first end 36 and the second end 38, which is the location where the liner 3 is subjected to tensile forces during collapse. The tensile strength of the fracture 45 is lower than that of the other portions. As shown, the breaking portion 45 is provided with a plurality of notches 46, the notches 46 are distributed at intervals along the circumferential direction, and the cumulative circumferential dimension of the notches 46 is not less than 40% of the circumferential dimension of the bush 3.

The outer circumferential surface 32 of the bush 3 is also provided with a plurality of projections 41, the projections 41 contacting the outer tube 2. The raised points 41 are located between the breaking portion 45 and the outer flange 39, while all of the ribs 33 are located between the breaking portion 45 and the first end 36, or, in an axial position, all of the ribs 33 are located between the breaking portion 45 and the inner flange 37. As the name implies, it will be readily understood by those skilled in the art that the volume of the protrusion 41 is small, and the contact surface of the protrusion 41 with the inner wall 21 of the outer tube 2 is much smaller than the contact surface of the rib 33 with the inner wall 21, for example, less than one tenth. The contact surface of the projection 41 is small enough to hold the bushing 3 in the gap accurately in position and also to hold the bushing in the gap after breaking, leading the direction of the break well.

The outer peripheral surface 32 of the first end 36 has an outer guide surface 43, and the outer guide surface 43 has a radial dimension that gradually decreases from the proximal end thereof toward the first end 36. That is, the radial dimension of the outer guide surface 43 decreases closer to the first end 36. Therefore, the outer tube 2 can be easily mounted on the liner 3 guided by the outer guide surface 43. The inner peripheral surface 31 of the second end 38 has an inner guide surface 44, and the inner guide surface 44 has a radial dimension that gradually increases from the proximal end thereof toward the second end 38. That is, the radial dimension of the inner guide surface 44 increases closer to the second end 38. When the bush 3 is axially mounted on the inner pipe 1, it can be easily mounted in place by the guiding action of the inner guide surface 44. The inner circumferential surface 31 is further provided with a stopper 42 extending from the inner flange 37 to the second end 38, the inner connecting end 10 is provided with a stopper groove 12, the stopper 42 is installed in the stopper groove 12, and the stopper 42 and the stopper groove 12 are matched with each other to limit the inner pipe 1 to rotate relative to the bushing 3.

Before the bush 3 is fitted into the clearance, the radial height of the rib 33 with respect to the outer peripheral surface 32 is larger than the clearance, that is, the rib 33 has a margin larger than the interference with which the bush 3 is fitted into the clearance. For convenience of illustration, the margin is shown as 33' in fig. 4. In the actual product, the margin 33' is cut off as described below. Since the outer circumferential surface 32 of the bush 3 has the specially configured guide portion 34, when the outer tube 2 is mounted to the bush 3 on the inner tube 1, the outer tube 2 can be mounted in place while maintaining a preferable coaxiality under the guidance of the guide portion 34, and the outer tube 2 can cut off the margin 33' of the top of the convex strip 33, so that the bush 3 has a proper interference in the gap between the outer tube 2 and the inner tube 1, and a proper collapsing force is obtained. Therefore, the steering column 100 is easy to manufacture and the collapse force is easy to meet the requirement.

The above detailed description is for the purpose of illustration only and not for the purpose of limitation, and various changes and modifications may be made by those skilled in the art without departing from the scope of the present disclosure. All equivalent solutions are therefore intended to be included within the scope of the present application, whose scope is defined in the following claims.

Claims

1. Steering column (100), characterized in that it comprises:

an inner tube (1) having an inner connection end (10) at one axial end;

an outer tube (2) having an outer connecting end (20) at one axial end, the outer connecting end (20) of the outer tube (2) being axially coaxially sleeved outside the inner tube (1) through the inner connecting end (10), and the outer tube (2) and the inner tube (1) having a radial gap therebetween to allow mutual movement thereof in a direction to shorten an axial length of the steering column (100); and

an injection molded bushing (3) installed in the gap, the bushing (3) having a cylindrical body (30), the body (30) having an inner circumferential surface (31) and an outer circumferential surface (32) which are diametrically opposed to each other, the outer circumferential surface (32) of the bushing (3) having a plurality of ribs (33) and a plurality of guide portions (34), the ribs (33) having a margin larger than an interference with the clearance of the bushing (3) before the bushing (3) is installed in the gap, the guide portions (34) being located between the ribs (33) and the inner connection end (10), the guide portions (34) gradually increasing in radial height from a position thereof near the inner connection end (10) toward the ribs (33) nearest thereto, a ratio of an axial length of the guide portions (34) to the radial height thereof being not less than 0.5 and not more than 1.8, the inner circumferential surface (31) contacts the inner pipe (1), at least part of the convex strips (33) are removed in the process of installation into the outer pipe (2), the convex strips (33) contact the inner wall (21) of the outer pipe (2) in an interference fit mode, and the outer circumferential surface (32) faces the inner wall (21) at intervals in the radial direction.

2. The steering column (100) according to claim 1, wherein the bushing (3) has axially opposite first and second ends (36, 38), an inner circumferential surface (31) of the first end (36) having an inwardly projecting inner flange (37), the inner flange (37) contacting the inner connection end (10) of the inner tube (1).

3. The steering column (100) according to claim 2, wherein the outer circumferential surface (32) of the second end (38) has an outwardly projecting outer flange (39), the outer flange (39) having a radial height relative to the outer circumferential surface (32) that is greater than the gap.

4. Steering column (100) according to claim 3, wherein the bushing (3) is further provided with a break (45), the break (45) being located between the inner flange (37) and the outer flange (39), the break (45) having a lower tensile strength than other locations subjected to tensile forces.

5. The steering column (100) according to claim 4, wherein the fracture (45) is provided with a plurality of notches (46), the notches (46) being circumferentially spaced apart, the cumulative circumferential dimension of the notches (46) being no less than 40% of the circumferential dimension of the bushing (3).

6. The steering column (100) according to claim 4, wherein the outer peripheral surface (32) of the bushing (3) is further provided with a plurality of protruding points (41), the protruding points (41) contacting the outer tube (2), the protruding points (41) being located between the breaking portion (45) and the outer flange (39).

7. The steering column (100) according to claim 2, wherein the outer peripheral surface (32) of the first end (36) has an outer guide surface (43), the outer guide surface (43) having a radial dimension that tapers from its proximal end in a direction toward the first end (36).

8. The steering column (100) according to claim 1, wherein a stopper (42) is further disposed on the inner circumferential surface (31), the inner connecting end (10) is provided with a stopper groove (12), the stopper (42) is mounted in the stopper groove (12), and the stopper (42) and the stopper groove (12) cooperate with each other to limit the inner tube (1) from rotating relative to the bushing (3).

9. The steering column (100) according to claim 3, wherein the outer tube (2) and the outer flange (39) have an axial spacing of not more than 15 mm.

10. The steering column (100) according to claim 1, wherein a radial height of the rib (33) relative to the outer circumferential surface (32) is greater than the gap before the bushing (3) is fitted into the gap.