JP2010069909A - Resin steering boot for center-takeoff type steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of deep wear by preventing a valley portion of a compressed-side bellows from strongly interfering with an axial end edge portion of an elongated hole in a gear housing. <P>SOLUTION: A center-takeoff type steering boot includes: a cylindrical section 2 fixed to a rack shaft via a joint 9 for connecting a tie rod which slides inside the elongated hole 5 formed in the gear housing along the axially longitudinal direction of the rack shaft accommodated in the gear housing 4; and a pair of bellows sections 3 which are disposed on both sides of the cylindrical section 2, with the end portion 6 thereof on the opposite side of the cylindrical section 2 being fixed to the gear housing 4, and which contract and extend following the movement of the cylindrical section 2 fixed to the joint 9; wherein the inside diameter of the valley portion 11 in the vicinity of the center of the bellows sections is smaller than the inside diameter of the valley portion 13 on the cylindrical section side. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a resin steering boot. More specifically, the present invention is fixed to the rack shaft via a tie rod coupling tool that slides in a long hole formed in the gear housing along the axial direction of the rack shaft accommodated in the gear housing. A pair of tubular portions that are disposed on both sides of the tubular portion and that extend opposite to the tubular portion and that extend and contract following the movement of the tubular portion that is fixed to the gear housing and fixed to the tie rod connector. The present invention relates to an improvement in the structure of a resin-made steering boot for a center take-off type steering device.

  A conventional steering boot used in a center take-off type steering device is an integral structure including a cylindrical portion and a bellows portion having a uniform diameter and a thickness disposed on both sides of the cylindrical portion, A cylindrical portion at the center is fixed to a connector that connects the rack shaft in the gear housing and an outer tie rod through the long hole of the gear housing, and the end portions of the bellows portions at both ends serve as attachment portions of the gear housing. The gear housing is covered by being fixed, and a seal structure is formed in which the left and right bellows portions expand and contract following the movement of the cylindrical portion interlocked with the movement of the rack shaft in the gear housing. It is provided to prevent dust and the like from entering.

  The cylindrical portion at the center of the boot is formed in a D-shaped cross section that constitutes a flat mounting surface, and two through holes are formed through the mounting surface to pass the connector. Each through hole is penetrated by a tie rod coupling connector that couples a T-shaped coupling member that couples the ball joints of the left and right tie rods arranged outside the gear housing and an inner rack shaft of the gear housing. . The tie rod connector includes, for example, a bolt, a stepped collar, and a guide shoe, and is spaced apart by an interposition of a stepped collar disposed on the inside of the boot. It is provided so that a shape connection member may be connected with a bolt. On the other hand, a guide shoe that slides in the through hole of the gear housing is fitted and supported on the shoulder portion of the stepped collar. Accordingly, the through hole of the cylindrical portion of the boot and the mounting surface around the through hole are sandwiched between the T-shaped connecting member and the guide shoe, the periphery of the through hole is sealed, and the cylindrical portion itself is fixed to the rack shaft.

JP 2001-187965 A JP 2001-151120 A

  However, in the structure of the conventional center take-off type steering boot, the tie rod coupler that slides in the long hole of the gear housing and the tubular portion at the center of the boot are coupled at one place on the circumference. Since the axial force applied to the cylindrical portion acts only at one location on the circumference of the cylindrical portion, it is impossible to maintain the complete posture of the cylindrical portion. For this reason, since the compression force acts only on one side of the bellows portion without acting as a parallel force that compresses the bellows uniformly in the axial direction in the bellows on the compression side, the bellows portion tends to buckle and deform meanderingly. is there. Since this buckling bends with the side where the force is applied inward, the bellows on the compression side is deformed so that the side fixed by the tie rod connector approaches the gear housing. If the meandering deformation due to the pressure increase in the boot accompanying the increase in the ambient temperature (engine room temperature) is added to this, the deformation of the compression side bellows further increases. For this reason, the trough portion of the compression side bellows strongly interferes and rubs with the axial end edge portion of the long hole of the gear housing, so that the trough portion may be locally worn and repeated, which may lead to penetration.

  Further, when the meandering deformation of the bellows portion increases, there is a problem that the central portion of the bellows protrudes most and causes interference with peripheral parts. In order to avoid this, peripheral parts must be kept away, but in reality, there are many parts that are not easy to move or change shape, such as subframes. On the other hand, making the entire bellows tight in order to suppress meandering deformation at the bellows portion, that is, reducing the gap with the gear housing increases the risk of wear.

  Therefore, the present invention provides a resin steering boot for a center take-off type steering device that prevents the trough portion of the compression side bellows from strongly interfering with the axial end edge of the long hole of the gear housing and prevents the occurrence of deep wear. The purpose is to provide.

  In order to achieve such an object, the invention described in claim 1 is a tie rod connecting tool that slides in a long hole formed in the gear housing along the axial direction of the rack shaft accommodated in the gear housing. Movement of the cylindrical part fixed to the rack shaft via the cylindrical part, and the cylindrical part arranged on both sides of the cylindrical part and fixed to the tie rod connector with the opposite end of the cylindrical part fixed to the gear housing In the resin take-up boot for the center take-off type steering apparatus, the inner diameter of the valley portion near the center of the bellows portion is made smaller than the inner diameter of the valley portion on the cylindrical portion side. I have to.

  Further, the invention according to claim 2 is the steering boot according to claim 1, wherein the trough near the center is located more than the edge of the long hole in the longitudinal direction when the tie rod connector is disposed at the neutral position. Is also positioned outside in the axial direction.

  According to a third aspect of the present invention, in the steering boot according to the first or second aspect, the bellows portion is gradually formed from a cylindrical portion at one end and an end portion fixed to the gear housing at the other end toward a trough near the center. It has a drum shape with a small valley diameter.

  According to a fourth aspect of the present invention, in the steering boot according to any one of the first to third aspects, the mountain diameter is reduced in accordance with the valley diameter.

  According to the resin-made steering boot for the center take-off type steering device according to claim 1, in the bellows on the compression side, when the bellows near the center is formed in the gear housing at the time of bellows deformation due to pressure increase in the boot or the operation of the steering device By abutting, in order to prevent deformation of the bellows part and prevent the valley of the bellows part near the cylindrical part from contacting or strongly interfering with the edge part of the long hole, Occurrence can be prevented. In other words, the bellows valley portion close to the cylindrical portion is supported by the valley portion near the center that is brought into contact with the gear housing at an early stage, and does not generate large deformation, and the bellows valley diameter (clearance) near the cylindrical portion is originally reduced. Since it is large, interference is reduced with respect to the axial end edge of the long hole that causes the most wear. Therefore, a boot having excellent durability (wearability) can be obtained.

  Further, when the bellows near the center is brought into contact with the gear housing at an early stage when the bellows is deformed due to the pressure increase in the boot or the operation of the steering device, the meandering deformation of the bellows can be suppressed. Moreover, it is possible to obtain a boot that does not have to worry about wearing even if it is not thick and has a thick bellows. Therefore, since the deformation amount of the bellows part due to pressure fluctuations is small and the interference with the peripheral members is small, the space can be saved and the vehicle mountability is excellent.

  According to the steering boot of claim 2, the valley portion near the center of the bellows on the compression side is surely brought into contact with the gear housing beyond the axial end edge of the elongated hole, so that the valley portion near the center. Since there is no danger of contact with the edge portion of the long hole, a boot having superior durability (wearability) can be obtained.

  Further, according to the steering boot according to claim 3, the change in the diameter of the bellows valley is formed in the hourglass shape in which the valley diameter gradually increases toward the both ends centering around the center, thereby avoiding a sudden change in diameter. Since the gradual change is made, sudden bending / deformation can be prevented even if the bellows part receives a biased compressive force.

  Further, according to the steering boot according to claim 4, since not only the valley diameter but also the mountain diameter is further reduced, the amount of bulge on the outer side of the compression side bellows warp (the side not fixed by the tie rod connector) Therefore, it can be accommodated with a small deformation, and interference with peripheral members is further reduced.

  Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.

  1 to 4 show an embodiment of a resin steering boot for a center take-off type steering apparatus according to the present invention. A resin boot 1 for a center take-off type steering apparatus according to this embodiment penetrates a long hole 5 of a gear housing 4 and connects a rack shaft (not shown) in the gear housing 4 and an outer tie rod (not shown). A cylindrical portion 2 fixed to the rack shaft via a connecting tool for connecting tie rods, and an end 6 on the opposite side of the cylindrical portion 2 disposed on both sides of the cylindrical portion 2 is fixed to the gear housing 4 and is cylindrical. And a pair of bellows portions 3 that expand and contract following the movement of the shape portion 2.

  As shown in FIGS. 3 and 4, the cylindrical portion 2 at the center of the boot is formed in a D-shaped cross section that constitutes a flat mounting surface 7, and two tie rod connecting tools are passed through the mounting surface 7. A through hole 8 is opened. The tie rod coupler includes, for example, a bolt (not shown), a stepped collar, and a guide shoe, and a rack shaft inside the gear housing 4 is spaced apart by a stepped collar disposed inside the boot. The outer tie rod T-shaped connecting member is connected with a bolt. On the other hand, a guide shoe that slides in the long hole 5 of the gear housing 4 is fitted and supported on the shoulder portion of the stepped collar. Accordingly, the through-hole 8 of the cylindrical portion 2 of the boot 1 and the peripheral mounting surface 7 are sandwiched between the T-shaped connecting member and the guide shoe, the periphery of the through-hole is sealed, and the cylindrical portion 2 itself is used as the rack shaft. Fixed. Although not shown, each through hole 8 is connected to a T-shaped connecting member that connects the ball joints of the left and right tie rods arranged outside the gear housing 4 and an inner rack shaft of the gear housing. Bolts constituting the tie rod connector are penetrated. In FIGS. 1 and 5, the contours of the stepped collar and the guide shoe in a combined state are indicated by imaginary lines and are denoted by reference numeral 9 as representing a tie rod coupling tool.

  On the other hand, a bellows attachment end 6 fixed to a predetermined attachment portion of the gear housing 4 is provided at an end of the bellows portion 3 opposite to the cylindrical portion 2. Therefore, by fixing the bellows mounting end 6 to the gear housing 4, the left and right bellows portions 3 expand and contract following the movement of the cylindrical portion 2 interlocked with the movement of the rack shaft in the gear housing. By configuring the seal structure, dust or the like is prevented from entering the gear housing 4 from the long hole 5.

  Here, the bellows portion 3 has an inner diameter of the valley portion 11 near the center smaller than an inner diameter of the valley portion 13 on the cylindrical portion side. Further, the trough portion 11 near the center is longer than the longitudinal edge 10 of the long hole 5 of the bellows portion 2 when the connecting tool 9 for connecting the tie rod is disposed at the neutral position (as shown in FIG. 1). Is also provided so as to be located outside in the axial direction. The axial position of the valley 11 near the center is such that the valley 11 does not contact the edge 10 of the long hole 5 when the bellows is compressed. It may be on the shape part side.

  The trough 11 near the center of the bellows and the trough 13 on the cylindrical portion side avoid a sudden change in diameter and gently change the inner diameter, so that the trough near the center of the trough 13 on the cylindrical portion side. The valley on the side is preferably changed so as to increase the inner diameter gradually or stepwise. Therefore, in the case of the present embodiment, the bellows portion 3 is gradually moved from the end portion of the cylindrical portion 2 at one end and the end portion fixed to the gear housing 4 at the other end, that is, the bellows mounting end portion 6 toward the trough portion 11 near the center. It is formed so as to form a drum shape with a small valley diameter. Furthermore, it is preferable to reduce the peak diameter in accordance with the valley diameter. In this case, the bellows portion 3 has a drum shape that gradually decreases from the bellows attachment end 6 on the opposite side to the cylindrical portion 2 toward the small-diameter mountain portion 12.

  In the case of this embodiment, the valley diameter in the middle of the bellows portion 3 is formed slightly smaller than the valley diameters at both ends. More specifically, it is formed to be about 2 mm smaller in diameter. If the clearance is set too small, the bellows portion and the gear housing are always rubbed when the steering device is operated, which is not preferable. On the other hand, if the clearance is too large, there is a problem that meandering deformation cannot be suppressed.

  Specifically, the bellows of the present embodiment is formed as an inner diameter X4> X3> X2> X1> X of a valley near the cylindrical portion 2, and further X <X1 <X2 <X3 toward the mounting portion at the end. <X4 is formed. That is, the bellows portion 3 has a drum shape that gradually decreases in diameter from the cylindrical portion 2 at one end and the bellows attachment end portion 6 at the other end toward the valley portion 11 near the center. Here, six valleys having a valley diameter X to be the valley portion 11 near the center are formed, and each of the valleys X1, X2, X3, and X4 is one valley. In addition, the peak diameter is reduced in accordance with the valley diameter. Specifically, the outer diameters of the peaks Y3> Y2> Y1> Y are formed, and further, Y <Y1 <Y2 <Y3 <Y4 is formed toward the end mounting portion. In this case, seven peaks of the outer diameter Y that become the minimum diameter portion 12 are formed, and each of the peaks Y1, Y2, Y3, and Y4 is one. It should be noted that at least one valley having a valley diameter X that becomes the valley portion 11 near the center and one having an outer diameter Y that becomes the small-diameter peak portion 12 may be one or more. Is preferred.

  Further, the width B of the mountain group on both sides of the valley group of the valley part 11 near the center is formed smaller than the width A of the mountain group of the small-diameter mountain part 12 (B <A). That is, the pitch B of the adjacent peaks is slightly narrower than the pitch of the peaks in the minimum diameter portion 11 (interval between the top of the peaks and the peak of the peaks: the width of the peaks) A. Thereby, it becomes a drum shape while ensuring rigidity. Further, the pitch of the peaks of the mountain group near the cylindrical portion is slightly widened again and formed with a pitch A. Thereby, a required stroke can be earned.

  The steering boot 1 is formed so that the cylindrical portion 2 has a strength that prevents at least the periphery of the holes 8 and 8 from being deformed when subjected to a reaction force due to deformation of the bellows portions 3 and 3. For example, deformation is reduced by providing axial and circumferential ribs and convex portions on the periphery of the flat portion 7, the periphery of the hole 8, and the cylindrical portion.

  According to the steering boot 1 configured as described above, when the bellows is deformed due to the pressure increase in the boot or the operation of the steering device, as shown in FIG. Near the bellows attachment end 6 side that is fixed to the gear housing 4 beyond the edge 10 (that is, outside the axial end edge 10 of the long hole 5), the trough 11 near the center quickly contacts the gear housing. By doing so, the valley group 13 closer to the cylindrical portion 2 than the valley portion 11 near the center is prevented from coming into contact with or strongly interfering with the edge 10 portion of the long hole 5 and rubbing. That is, the bellows valley portion 13 near the cylindrical portion 2 is supported by the valley portion of the valley portion 11 in the vicinity of the center that is brought into contact with the gear housing at an early stage and does not generate a large deformation. The interference is reduced with respect to the axial end edge 10. In addition, the amount of overhang on the outer side of the warping of the bellows on the compression side (the side not fixed by the tie rod connecting tool) is also suppressed. In addition, since the peak diameter is also formed in a drum shape like the valley diameter, the valley portion 11 near the center of the bellows where the displacement is the most can be accommodated with a small deformation, so that there is almost no overhang.

  The above-described embodiment is an example of a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the scope of the present invention. For example, in the present embodiment, the bellows portion has a drum shape in which the valley diameter gradually decreases from one end toward the valley near the center, and gradually increases from the valley near the center toward the other end again. However, in some cases, the inner diameter may be changed stepwise.

1 is a longitudinal end view showing an embodiment of a resin steering boot for a center take-off type steering apparatus according to the present invention, showing a state in which a tie rod connector is arranged at a neutral position. It is explanatory drawing which shows the relationship between the valley diameter of the bellows part of the steering boot, and a crest diameter. It is an enlarged front view of the cylindrical part of the steering boot. It is a cross-sectional view which crosses the through-hole part of the cylindrical part of the steering boot. It is explanatory drawing which shows the deformation | transformation state of the trough and the mountain of the bellows part by the side of the compression of the steering boot.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Steering boot 2 Cylindrical part 3 Bellows part 4 Gear housing 5 Long hole 6 End part fixed to the gear housing 4 of a bellows part (bellows attachment end part)
8 Through hole 9 Tie rod connector (only the guide shoe and collar outline are shown)
DESCRIPTION OF SYMBOLS 10 Axial edge edge of long hole provided in gear housing 11 Valley part near center 12 Small diameter mountain part 13 Valley group near cylindrical part 2 14 Valley group near bellows attachment end part 6

Claims (4)

A cylindrical portion fixed to the rack shaft via a tie rod connecting tool that slides in a long hole formed in the gear housing along the axial length direction of the rack shaft housed in the gear housing; A pair of ends that are disposed on both sides of the cylindrical portion and that are opposite to the cylindrical portion are fixed to the gear housing and expand and contract following the movement of the cylindrical portion fixed to the tie rod connector. In the resin take-up boot for the center take-off type steering apparatus provided with the bellows portion, the center take-off type characterized in that the inner diameter of the valley portion near the center of the bellows portion is smaller than the inner diameter of the valley portion on the cylindrical portion side. Resin steering boots for steering devices. The trough near the center is located on the axially outer side from the longitudinal edge of the elongated hole when the tie rod connector is disposed at the neutral position. 1. A resin steering boot for a center take-off type steering device according to 1. The bellows portion has a drum shape that gradually decreases in diameter from the cylindrical portion at one end and the end fixed to the gear housing at the other end toward the trough near the center. A resin steering boot for a center take-off type steering apparatus according to claim 1 or 2. The resin steering boot for a center take-off type steering device according to any one of claims 1 to 3, wherein a mountain diameter is reduced in accordance with the valley diameter.

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