JPH0285568A - Protective bellows for rack pinion mechanism - Google Patents

Abstract

PURPOSE:To extend the life of protective bellows by making the thickness on the rack pinion side smaller than the thickness of the bellows in the range of the sway motion on the tie rod side connected to a rack bar. CONSTITUTION:Protective bellows 5 made or rubber or the like are arranged between a rack housing 1 and a tie rod 4. When the rack bar 2 is moved in the axial direction, circular ridge sections 7 and valley sections 8 located at the thin portion of the bellows 5 on the rack pinion side are mainly shrunk or expanded to follow the axial movement of the rack bar 2. On the other hand, when the tie rod 4 is swayed centering a ball joint 3, ridge sections and valley sections located at the thick portion 5a of the bellows 5 on the tie rod 4 side are bent to follow the sway. No large stress is concentrated at one position of the bellows, and the partial deterioration phenomenon of the bellows themselves can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a protective bellows for a rack and pinion mechanism in the steering of a motor vehicle.

2. Description of the Related Art As shown in FIG. 3, a tie rod 4 is attached to one end of a rack bar 2 that is disposed within a rack bar housing 1 and projects from the rack bar housing 1 through a ball joint 3. and the other end of the rack bar 2 is connected to a rack and pinion mechanism (not shown) to transmit the rotational motion of the steering shaft from the rack bar 2 to the tie rod 4 via the ball joint 3. The wheels are steered by movement of the tie rod 4 in the axial direction.

In such a rack and pinion mechanism, a bellows 5 made of an elastic material such as rubber is surrounded and fixed, and this prevents moisture and soot from entering the rack bar housing 1 and the ball joint 3, and preventing dust from adhering to the rack bar housing 1 and the ball joint 3. Care has been taken to ensure that there are no

As shown in the figure, the bellows 5 has a structure in which annular peaks 7.7 and valleys 8, 8 are alternately connected in the axial direction, and one end of the bellows 5 is connected to the rack bar. A tie rod 4 is fixed to the end 1a of the housing 1, while the other end of the bellows 5 is connected via a ball joint 3 to the end of the rank par 2 disposed within the rack bar housing. It is fixed to the joint side end 4a and completely surrounds the end 1a of the rack bar housing 1 to the end 4a of the tie rod 4.

In the bellows 5, the annular peaks 7 and troughs 8 expand and contract in response to the axial movement of the rack bar 2 to follow the axial movement of the rank par 2, while the ball joint 3
Even when the tie opening swings around arrows 1 and 4, these peaks 7 and troughs 8 bend to follow the swing, thereby controlling the operation of the rack bar 2 and tie rod 4. A structure is provided that does not impose extra loads.

Regarding the above, Japanese Patent Application Laid-Open No. 134277/1983 describes the forming radius of the crests 7 and troughs 8 of the rack bar housing 1 in the range that involves the rocking movement of the tie rod connecting portion of the bellows 5. A configuration is disclosed in which the number is gradually increased from the connecting portion side to the tie rod connecting portion side.

Furthermore, Japanese Patent Application Laid-Open No. 55-20966 discloses that thick portions, protrusions, etc. are formed on one or both of the outer circumferential surface of the peak portion 7 and the inner circumferential surface of the valley portion 8, or the application of a wear-resistant material, etc. A structure is disclosed in which the abrasion resistance of the bellows 5 itself is increased by implementing the following measures.

Problems to be Solved by the Invention However, in the structure of the protective bellows of such a conventional rack and pinion mechanism, stress is concentrated in a specific part of the bellows 5 during operation, and the rubber constituting the bellows 5 is damaged. There has been a problem in that the deterioration of the material may be accelerated and the life of the bellows 5 itself may be shortened. That is, among the rubber materials constituting the bellows 5, the rubber material on the rack/binion side is subjected to only expansion and contraction movement in the axial direction, whereas the rubber material on the tie rod 4 side shown in range Q In addition to the above-mentioned expansion and contraction movement, the swinging movement shown by the arrow A accompanying the operation of the ball joint 3 is added, so that the swinging movement causes severe deterioration of the bellows portion constituting the bellows 5, which reduces the durability of the bellows 5. will decrease.

In order to deal with the above, as described in the above-mentioned Japanese Patent Application Laid-Open No. 58-134277, the forming radii of the crests 7 and troughs 8 in the range where the tie rod connecting portion of the bellows 5 oscillates are determined. Even if the rack bar housing l is gradually increased in size from the connecting part side to the tie rod connecting part side, it is not necessarily possible to prevent the deterioration of the bellows part caused by rocking, and furthermore, in Japanese Patent Laid-Open No. 55 As described in Japanese Patent Application Publication No. 20966, means such as forming thick parts, protrusions, etc. on one or both of the outer circumferential surface of the peak portion 7 and the inner circumferential surface of the valley portion 8, or applying a wear-resistant material, etc. By applying
Although the wear resistance of the bellows 5 itself can be improved, it is less effective in preventing deterioration of the rubber material due to the swinging movement of the bellows 5.
It is difficult to form protrusions and the like, resulting in an increase in cost.

Therefore, the present invention solves various problems that the protective bellows of the conventional rack and binion mechanism have, and
It is an object of the present invention to provide a protective bellows which has a simple structure, can eliminate stress concentration on a specific part of the bellows during operation, and can extend the life of the rubber material constituting the bellows. It is.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention has annular peaks and valleys connected alternately in the axial direction, and one end of which is connected to a rack bar.
One end is fixed to the end of the housing, and the other end is fixed to the joint side end of a tie rod connected via a ball joint to the end of the rack bar disposed in the rack bar housing. A protective bellows for a rack and binion mechanism, which is made of an elastic material and is disposed from the end of the rack bar housing to a portion surrounding the ball joint, is connected to the rack bar and is in a range that involves swinging movement on the tie rod side. The wall thickness of the bellows on the rack/binion side connected to the rack bar is smaller than the wall thickness of the bellows.

According to this configuration, when the rack bar moves in the axial direction, the annular peaks and valleys located in the thin walled portion of the bellows mainly on the rack/binion side expand and contract.
While following the axial movement of the rack bar, when the tie rod swings around the ball joint, the peaks and valleys of the thick portion of the bellows on the tie rod side bend. , it is possible to follow the above-mentioned rocking motion. Therefore, there is no partial concentration of stress on the bellows due to swinging of the tie rod, and an effect is obtained in which no unnecessary load is applied to the operation of the rack bar and tie rod. In other words, when the rack bar expands and contracts, most of the stress is applied to the thin part of the bellows, and this stress can be absorbed, while when the tie rod swings, most of the stress is applied to the thick part of the bellows. Since the stress of
The stress caused by this rocking is absorbed by the thick portion, so that large stress is not concentrated in one place on the bellows, and local deterioration of the bellows itself is prevented.

EXAMPLE Referring to FIGS. 1 and 2 in the drawings, an example of a protective bellows for a rack and pinion mechanism according to the present invention will be described, with the same reference numerals being given to the same components as in the conventional structure. This will be explained in detail.

FIG. 1 shows a basic embodiment of the present invention. In the figure, 1 is a rack bar housing.
A tie rod 4 is connected to one end of a rack bar 2 disposed in the housing 1 via a ball joint 3, and the other end of the rack bar 2 is connected to a rack (not shown).
It is connected to a pinion mechanism to transmit the rotational motion of the steering shaft from the rack bar 2 to the tie rod 4 via the ball joint 3, and the wheels are steered by the axial movement of the tie rod 4.

5 is a telescopic bellows made of elastic material such as rubber;
One end of the bellows 5 is fixed to the end 1a of the rack bar housing l, while the other end of the bellows 5 is fixed to the joint side end 4a of the tie rod 4. The area from the end la of the rack part/housing l to the joint side end 4a of the tie rod 4 is surrounded to prevent moisture and splash from entering the rack bar housing 1 and the ball joint 3, and from dust adhering. I try not to.

As shown in the figure, the bellows 5 has a structure in which annular peaks 7.7 and valleys 8, 8 are alternately connected in the axial direction, and is located on the tie rod 4 side shown in range a. The wall thickness of the other bellows 5 on the rack and pinion side connected to the rack bar 2 is greater than the wall thickness of the bellows 5 in the range where the rubber material, i.e., the swinging motion of the tie rod 4' is shown in the arrow. In other words, the feature of the present invention is that the thick portion 5a is formed in the rubber material shown in the range g.

According to this configuration, when the rack bar 2 moves in the axial direction, the annular peaks 7 and troughs 8 located in the thin walled portions of the bellows 5 mainly on the rack and pinion side expand and contract, and the rack bar 2 expands and contracts. -2, and when the tie rod 4 swings around the ball joint 3, the tie rod 4 shown in the range Q of the bellows 5
The peak portions 7 and valley portions 8 of the thick wall portion 5a located on the side are bent and can follow the above-mentioned rocking motion. Therefore, the partial stress concentration on the bellows 5 caused by the swinging of the tie rod 4 is eliminated, and the back bar 2. A protective bellows structure is provided that does not impose an extra load on the operation of the tie rod 4. In other words, when the rack bar 2 expands and contracts, most of the stress is applied to the thin walled portion of the bellows 5, and this stress can be absorbed, while when the tie rod 4 swings, the thickness of the bellows 5 Since most of the stress is applied to the thick portion 5a, the stress caused by the rocking can be absorbed by the thick portion 5a. Therefore, in any case, a large stress will not be concentrated in one place on the bellows 5, and it becomes possible to prevent the phenomenon of partial deterioration of the bellows 5 itself.

FIG. 2 shows a modification of the present invention, the basic configuration of which is the same as that of FIG. 1, and is indicated by the same reference numerals. That is, in this example, the above range Q
Among the thick portions 5a on the tie rod 4 side shown by , the height of a portion of the ridge portion 7' is lower than the height of the other ridge portion 7. According to such a configuration, the mountain portion 7'
The elasticity of the rubber material in this part further decreases, and when the lever 2 expands and contracts, the elasticity of the thin walled part of the bellows 5 on the rack and pinion side increases, and when the tie rod 4 swings. This brings about the effect that the resistance component of the bellows 5 can be lowered.

Effect of the invention As explained in detail above, the present invention is applicable.

According to the protective bellows of the rack and pinion mechanism, the annular peaks and valleys are alternately connected in the axial direction, and the - end is fixed to the end of the rack bar housing, while the other end is fixed to the end of the rack bar housing. It is fixed to the joint side end of a tie rod connected to the end of the rack bar disposed in the rack bar housing via a ball joint, and extends from the rack par 7 to the housing end to a portion surrounding the ball joint. In the protective bellows of the rack and pinion mechanism, which is made of an elastic material, the thickness of the bellows is greater than the thickness of the bellows that is connected to the rack bar and is within the range where the tie rod side oscillates.
Since the protection bellows of the rack and pinion mechanism is configured such that the wall thickness of the bellows on the rack and pinion side connected to the rack bar is smaller, the following effects are brought about. That is, when the rack bar moves in the axial direction, the annular peaks and valleys located in the thin walled portion of the bellows mainly on the rack and pinion side expand and contract to follow the axial movement of the rack bar. When the tie rod swings about the ball joint, the peaks and valleys of the thicker portion of the bellows on the tie rod side bend to follow the swing. Therefore, the partial concentration of stress on the bellows due to the swinging of the tie rod is eliminated, resulting in the effect that no unnecessary load is applied to the operation of the rack bar and tie rod. That is, when the rack bar expands and contracts, most of the stress is applied to the thin walled part of the bellows, which can absorb this stress, while the stress caused by the swinging is applied to the tie rod side part and the stress caused by the swinging is absorbed by the thick wall. Since the support can be stopped by the part, large stress is prevented from concentrating in one place on the bellows, and the life of the rubber material that makes up the bellows can be extended.

Furthermore, the protective bellows according to the present invention has a simple structure and can be manufactured by integral molding means, so that it exhibits the advantage that manufacturing costs are reduced.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a main part showing one embodiment of the protective bellows for a rack and pinion mechanism according to the present invention, FIG. 2 is a cross-sectional view of a main part showing another embodiment of the present invention, and FIG. FIG. 2 is a sectional view of a main part of an example of a protective bellows. l...Rack bar housing, 2...Rack bar 1
3... Ball joint, 4... Tie rod, 5...
...Bellows, 5a...Thick wall part, 7...Mountain part, 8.
・・Tanibe, 2 others

Claims (1)

[Claims] (1) A rack in which annular peaks and valleys are alternately connected in the axial direction, one end is fixed to the end of the rack bar housing, and the other end is disposed within the rack bar housing. A rack and pinion mechanism made of an elastic material fixed to the joint side end of a tie rod connected to the end of the bar via a ball joint, and disposed at a portion surrounding the ball joint from the end of the rack bar housing. In the protective bellows, the wall thickness of the bellows on the rack and pinion side connected to the rack bar is greater than the wall thickness of the bellows on the rack and pinion side connected to the rack bar and in the range that involves rocking movement on the tie rod side. A protective bellows for a rack and pinion mechanism characterized by being formed to be small.