JP2006258159A - Boot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boot capable of inhibiting meandering even upon occurrence of large stress. <P>SOLUTION: The boot is made of resin for covering a boll joint interposed between a mating large-diameter member and a mating small-diameter member and is characterized by comprising a large-diameter attachment part fixedly attached to the mating large-diameter member, a first bellows part following the large-diameter attachment part, a polygonal ridge part interposed between the first bellows part and a second bellows part and separating continuous meandering motion of the first bellows part and the second bellows part, the second bellows part following the first bellows part through the polygonal ridge part, a tapered bellows part following the second bellows part, and a small-diameter attachment part following the tapered bellows part and fixedly attached to the mating small-diameter member. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a boot attached to a steering device of a rack and pinion type steering, for example.

  The steering boot covers a ball joint between the steering gear box and the tie rod. That is, one end of the steering boot is fixed to the end of the steering gear box. The other end of the steering boot is fixed to the tie rod. The steering boot is disposed close to the engine. For this reason, the environmental temperature near the steering boot is relatively high. Therefore, the air sealed inside the steering boot expands.

  FIG. 4 shows an axial side view of the steering boot. As shown in the drawing, when the air inside the steering boot 100 expands, the steering boot 100 expands and deforms. Then, the steering boot 100 meanders so as to wave in an S shape. When the steering boot 100 meanders, the steering boot 100 comes into sliding contact with a built-in ball joint (not shown) or a clamp. For this reason, the steering boot 100 may be defective. The steering boot 100 is made of resin. For this reason, once deformed meandering, it is difficult to restore the original shape even when cooled.

In view of this point, Patent Document 1 introduces a steering boot that suppresses meandering. According to the steering boot described in this document, U-shaped circumferential grooves are recessed in the three bellows valleys counted from the side fixed to the end of the steering gear box 102. For this reason, the radial stiffness of the bellows having these circumferential grooves is higher than the radial stiffness of the bellows of other portions. Therefore, the steering boot described in the document is difficult to meander.
JP-A-10-238629

  However, according to the steering boot described in the same document, the circumferential groove provided to increase the rigidity increases the radial composition as compared with the radial rigidity of the bellows of other parts, and the stress of meandering is reduced. It can be considered that the effect is effective only in a relatively small case.

  The boot of the present invention has been completed in view of the above problems. Therefore, an object of the present invention is to provide a boot that can suppress meandering even when a greater stress occurs.

  In order to solve the above problems, the boot of the present invention is a resin boot that covers a ball joint interposed between a counterpart large diameter member and a counterpart small diameter member, A large-diameter fastening portion to be fastened, a first bellows portion connected to the large-diameter fastening portion, and the first bellows portion and the second bellows portion interposed between the first bellows portion and the second bellows portion. A polygonal peak portion that divides the continuous bellows motion of the bellows portion, a second bellows portion that is continuous with the first bellows portion via the polygonal peak portion, a tapered bellows portion that is continuous with the second bellows portion, And a small-diameter fastening part that is connected to the tapered small-diameter member and is connected to the tapered bellows part. By adopting such a configuration, the high radial rigidity of the polygonal peak portion divides the continuous bellows movement of the first bellows portion and the second bellows portion, and the meandering deformation of the first bellows portion and the second bellows portion is caused. Be regulated.

  Preferably, the outer peripheral shape of the polygonal crest is preferably not less than a quadrangle and not more than an octagon. When the octagon is exceeded, the difference between the distance between one side of the polygon and the central axis and the distance between the vertex of the polygon and the central axis becomes small, making it difficult to obtain shape rigidity due to the polygonal shape. And the difference will disappear. In addition, if it is a triangle, the difference in the distances becomes too large, and there are cases where it is difficult to establish a shape such as interference inside the hypotenuse or interference outside the apex.

  Preferably, the mountain-valley connecting surface of the polygonal peak is preferably formed at a constant inclination angle. By adopting such a configuration, the axial length of the outer peripheral surface of the polygonal crest changes, and the axial length of the outer peripheral surface decreases as the distance from the central axis increases, and shape rigidity is obtained. Moreover, since it is a constant inclined surface, there are few metalworking steps and it can contribute to cost reduction.

  Preferably, the arrangement position of the polygonal mountain portion is preferably arranged at a substantially central position of the axial length of the second bellows portion from the first bellows portion. By arranging at the center position in the axial length, the deformation is shared by both the first bellows part and the second bellows part, and the meandering is suppressed by reducing the deformable amount.

  Preferably, the end of the ball joint is accommodated in the tapered bellows. With such a configuration, the tapered bellows portion comes into contact with the end portion of the ball joint shortly after the deformation. It is restricted by the ball joint, and the taper bellows part is not deformed any more. With this configuration, the bellows movement of the tapered bellows part in addition to the first bellows part and the second bellows part can be suppressed, which further contributes to the suppression of meandering of the entire boot.

According to the present invention, the meandering of the boot can be effectively suppressed against a large stress due to the shape effect of the polygonal ridge and the division effect of the bellows movement.

  Hereinafter, a steering boot (hereinafter abbreviated as “boot”) as an embodiment of the boot of the present invention will be described.

  First, the installation position of the boot of this embodiment is demonstrated. FIG. 1 shows a mounting view of the boot of this embodiment. As shown in the figure, the handle 90 is connected to a steering column 91. The steering column 91 is connected to a pinion (not shown) built in the steering gear box 93 via a universal joint 92. The pinion meshes with a rack (not shown) that is also built in the steering gear box 93. The rack end and the tie rod 94 are connected via a ball joint (not shown). The ball joint is covered with a boot 1.

  When the driver turns the handle 90, the turning force is transmitted to the pinion via the steering column 91 and the universal joint 92. The pinion meshes with the rack. For this reason, the rack reciprocates in the vehicle width direction by the rotational movement of the pinion. The rack protrudes and is immersed in the end of the steering gear box 93. The reciprocating motion of the rack is transmitted to the front wheel 95 (indicated by a one-dot chain line in the figure) via the tie rod 94. Thus, the rudder angle of the front wheel 95 is adjusted.

  Here, the large-diameter fastening portion 2 of the boot 1 is fastened to the end of the stationary steering gear box 93. On the other hand, the small diameter fixing portion 3 of the boot 1 is fixed to a tie rod 94 that reciprocates. For this reason, the boot 1 expands and contracts in the vehicle width direction. Further, as described above, the rack end and the tie rod 94 are connected via the ball joint. For this reason, the boot 1 bends according to the swing of the tie rod 94. The steering gear box 93 is included in the counterpart large-diameter member of the present invention. The tie rod 94 is included in the counterpart small diameter member of the present invention.

Next, the structure of the boot of this embodiment is demonstrated. In FIG. 2, the perspective view of the boot of this embodiment is shown. FIG. 3 shows an axial sectional view of the boot. As shown in these drawings, the boot 1 includes a large-diameter fastening portion 2 and a small-diameter fastening portion 3, a first bellows portion 4, a second bellows portion 5, a tapered bellows portion 6, and a first bellows portion. 4 and the second bellows portion 5 are provided with a polygonal mountain portion 7 arranged so as to be divided in the axial direction. The boot 1 is made of resin and is integrally manufactured by blow molding.
The large-diameter fastening part 2 has a ring shape. A clamp 20 is wrapped around the large-diameter fastening part 2. The large-diameter fastening part 2 is fastened and fixed to the outer peripheral surface of the steering gear box 93 by the clamp 20.

  The first bellows portion 4 has a cylindrical bellows shape continuous with the large-diameter fastening portion 2. The inner peripheral diameters of the four bellows constituting the first bellows portion 4 are substantially the same. Similarly, the valley inner peripheral diameters of the four bellows are almost the same. A part of the rack 930 is coaxially accommodated on the inner peripheral side of the first bellows part 4.

  The 2nd bellows part 5 is exhibiting the cylindrical bellows shape which continues to the 1st bellows part 4 across the polygonal mountain part 7 mentioned later. The inner peripheral diameters of the four bellows constituting the second bellows portion 5 are substantially the same. Similarly, the valley inner diameters of the four bellows are almost the same. On the inner peripheral side of the second bellows portion 5 at the time of the bellows neutral set length, an end portion of the rack 930 and a ball receiving member 961 fixed to the rack 930 are accommodated coaxially. A ball member 960 is rollably accommodated on the inner peripheral side of the concave portion of the ball receiving member 961. A ball joint 96 is constituted by the ball receiving member 961 and the ball member 960. The ball center A of the ball member 960 is accommodated on the inner peripheral side of the second bellows portion 5. The sphere center A is included in the swing center of the present invention.

  Here, the inner diameter of the valley of the first bellows portion 4 of the present embodiment is set to the same dimension as the inner diameter of the valley of the second bellows portion 5, but the inner diameter of the valley of the first bellows portion 4 The inner diameters of the peaks and valleys of the second bellows portion 5 do not have to be the same, and may be set with different dimensions.

  The tapered bellows portion 6 is connected to the second bellows portion 5 and has a tapered cylindrical bellows shape whose diameter is reduced toward the small-diameter fastening portion 3 described later. An end portion 962 of the ball receiving member 961 is accommodated on the inner peripheral side of the tapered bellows portion 6. Further, a part of the tie rod 94 fixed to the ball member 960 is accommodated coaxially.

  The small diameter fastening portion 3 has a ring shape. The small diameter fastening part 3 is connected to the end part on the small diameter side of the tapered bellows part 6. A clamp 30 is wrapped around the small diameter fastening portion 3. The small diameter fixing portion 3 is fastened and fixed to the outer peripheral surface of the tie rod 94 by the clamp 30.

  The polygonal mountain portion 7 has a pentagonal outer peripheral shape, and is arranged so as to divide the first bellows portion 4 and the second bellows portion 5 in the axial direction. Further, the axial position of the polygonal mountain portion 7 is set at a substantially central position from the end of the first bellows portion 4 on the side of the large diameter fastening portion 2 to the end of the second bellows portion 5 on the side of the small diameter fastening portion 3. Has been. Since the polygonal mountain portion 7 is in the center of the axial length of the two bellows portions, the continuous bellows length can be divided into the first bellows portion 4 and the second bellows portion 5. If it does in this way, continuous deformation cannot be performed with a short bellows length, and meandering can be effectively suppressed. Furthermore, since the mountain-valley coupling surface 70 that leads from the valley circular shape to the polygonal peak is at a constant inclination angle, the outer peripheral surface 71 of the polygonal peak 7 has changed in axial length, and from the central axis The longer the distance, the shorter the axial length of the outer peripheral surface 71 and the higher the shape rigidity. For this reason, bellows movement is suppressed and it contributes to suppression of meandering. Moreover, since it is formed with a constant inclined surface, the number of mold processing steps is small and the cost can be reduced.

  Next, the movement of the boot of this embodiment will be described. When the environmental temperature in the vicinity of the boot 1 rises, the air sealed inside the boot 1 expands. For this reason, stress in the direction of expansion / expansion is applied to the boot 1. At this time, the first bellows portion 4 and the second bellows portion 5 start to deform in the radial direction, but the polygonal mountain portion 7 is interposed between the first bellows portion 4 and the second bellows portion 5, and many Due to the high radial rigidity of the square shape, it works to break the continuity of the bellows movement. That is, the first bellows part 4 and the second bellows part 5 will stop soon after the bellows movement is started. Since the polygonal mountain portion 7 is arranged at the center position, the relative deformation amount of the first bellows portion 4 and the second bellows portion 5 can be made the same, and the total deformation amount can be minimized. . Therefore, the meandering deformation of the first bellows portion 4 and the second bellows portion 5 is restricted. Naturally, the stress in the diameter expanding direction is also applied to the tapered bellows portion 6. The taper bellows portion 6 is also deformed by this stress. However, the end portion on the large diameter side of the tapered bellows portion 6 is close to the end portion 962 of the ball receiving member 961. Therefore, the tapered bellows portion 6 abuts against the end portion 962 of the ball receiving member 961 shortly after the start of deformation. For this reason, the deformation | transformation of the taper bellows part 5 is controlled.

  Next, the effect of the boot of this embodiment is demonstrated. According to the boot 1 of the present embodiment, the first bellows portion 4 and the second bellows portion 5 are obtained by a relatively simple means of setting the polygonal portion 7 between the first bellows portion 4 and the second bellows portion 5. The continuity of the bellows movement can be cut off, and the meandering of the boot can be suppressed. For this reason, the number of mold processing steps is small and the cost is low.

Further, according to the boot 1 of the present embodiment, the tapered bellows portion 6 comes into contact with the end portion 962 of the ball receiving member 961 soon after the deformation. For this reason, a deformation | transformation of the taper bellows part 6 can be controlled. Thus, according to the boot 1 of the present embodiment, the first bellows portion 4 and the second bellows portion 5 are separated from the bellows movement by the polygonal mountain portion 7 and the shape effect, and the tapered bellows portion 6 is in contact with the ball joint 96. Each contact can suppress deformation. Therefore, the meandering suppression effect is high.
The embodiment of the boot 1 of the present invention has been described above. However, the embodiment is not particularly limited to the above embodiment. Various modifications and improvements that can be made by those skilled in the art are also possible.

For example, in the above-described embodiment, the position of the polygonal mountain portion 7 is set at a substantially central position of the axial length of the first bellows portion 4 and the second bellows portion 5. However, the position of the polygonal mountain portion 7 is not particularly limited to the above-described setting position, and may be a position biased toward the large-diameter fastening portion 2 or the small-diameter fastening portion 3 side. When the gap between the valley inner diameter of the second bellows portion 5 and the outer diameter of the ball joint 96 is small, the second bellows 5 comes into contact with the ball joint 96 shortly after the start of the bellows deformation, and the deformation is restricted. . In this case, the polygonal peak portion 7 may be arranged at the center position of the length from the first bellows portion 4 to the valley portion of the second bellows portion 5 and the contact axial direction position of the ball joint 96. Moreover, in the said embodiment, the mountain-valley connection surface 70 connected to a polygon-shaped mountain part from a valley circular shape has a fixed inclination angle. However, the inclination angle of the mountain / valley connection surface 70 is not limited to a constant value, and the axial direction length of the outer peripheral surface 71 of the polygonal mountain portion 7 may be constant and the inclination angle of the mountain / valley connection surface 70 may be changed. Moreover, in the said embodiment, the polygonal periphery mountain part 7 is a pentagon. However, the polygonal mountain portion 7 is not particularly limited, and a range from a quadrangular shape to an octagonal shape is preferable.

It is an attachment figure of the boots used as one embodiment of the present invention. It is a perspective view of the boot. It is an axial sectional view of the boot. It is an axial side view of the conventional steering boot.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Boot 2 Large diameter fastening part 3 Small diameter fastening part 4 1st bellows part 5 2nd bellows part 6 Tapered bellows part 7 Polygonal mountain part 20 Clamp 30 Clamp 70 Yamatani connection surface 71 Outer surface 90 Handle 91 Steering column 92 Universal Joint 93 Steering gear box 94 Tie rod 95 Front wheel 96 Ball joint 930 Rack 960 Ball member 961 Sphere receiving member 962 End A Sphere center

Claims (5)

  A resin boot covering a ball joint interposed between a counterpart large diameter member and a counterpart small diameter member, a large diameter fastening portion fastened to the counterpart large diameter member, and the counterpart A small diameter fastening portion fastened to the side small diameter member, a first bellows portion continuous to the large diameter fastening portion, a tapered bellows portion continuous to the small diameter fastening portion, and a second bellows portion continuous to the taper bellows portion And a polygonal mountain portion that is interposed between the first bellows portion and the second bellows portion and divides the continuous bellows movement of the first bellows portion and the second bellows portion. Features boots.   The boot according to claim 1, wherein an outer peripheral shape of the polygonal mountain portion is not less than a quadrangle and not more than an octagon.   The boot according to claim 1, wherein the mountain-valley connection surface of the polygonal peak is formed at a constant inclination angle.   4. The boot according to claim 1, wherein the polygonal mountain portion is disposed at a substantially central position of an axial length of the second bellows portion from the first bellows portion. The boot according to claim 1, wherein an end portion of the ball joint is accommodated in the tapered bellows portion.

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