JP4746728B2 - Resin steering boots for center take-off type steering devices - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resin steering boot. More specifically, the present invention relates to a resin steering boot structure for a center take-off type steering device having a cylindrical portion having a hole through which an output take-out means of the steering device passes and an expandable bellows portion disposed on both sides thereof. Regarding improvements.
[0002]
[Prior art]
A conventional steering boot used in a center take-off type steering device (rack and pinion type power steering device) is a uniform meat comprising a circular cylindrical portion that does not expand and contract and bellows portions that are arranged on both sides of the circular cylindrical portion. Thick one-piece structure with a cylindrical part that has a hole through which an output takeout bolt for attaching a mounting plate to which the steering tie rod is connected to the rack, that is, a means for taking out the output to the steering wheel from the center of the rack is provided. It has been.
[0003]
In the case of this center take-off type steering boot, the output take-out is interposed between the mounting plate to which the steering tie rod is connected and the rack so that dust or the like does not enter from the hole through which the output take-out bolt of the cylindrical portion is passed. The hole is closed by a cylindrical spacer covering the periphery of the bolt. The outer circumferential surface of the spacer is provided with an annular groove that fits into the edge of the hole in the cylindrical part, and the edge of the hole is sandwiched between the inside and outside of the edge of the annular groove of the spacer to cover the hole without any gaps. Are provided so as not to invade (see Japanese Utility Model Laid-Open No. 57-124275), and are sandwiched between a rigid body and a mounting plate to cover the periphery of the hole without a gap.
[0004]
[Problems to be solved by the invention]
However, in the conventional center take-off type steering boot structure, the cylindrical part receives the force when the bellows part expands and contracts, and the cylindrical part is deformed and stress is concentrated near the hole. For this reason, there is a possibility that the edge portion around the hole is warped and detached from the annular groove of the spacer to impair the sealing performance. Moreover, in order to improve the sealing performance while maintaining a good fitting state between the spacer and the hole, it is necessary to make the periphery of the hole in the cylindrical part a flat surface. The force from the portion cannot be uniformly distributed over the entire cylindrical portion, but concentrates on the peripheral portion of the hole having the weakest strength, and the peripheral portion of the hole is easily deformed.
[0005]
Accordingly, an object of the present invention is to provide a resin-made steering boot for a center take-off type steering apparatus having a structure in which the cylindrical portion is difficult to deform and the sealing performance of a hole through which an output take-out bolt is passed can be improved. To do.
[0006]
[Means for Solving the Problems]
In order to achieve such an object, the invention described in claim 1 includes a cylindrical portion having a hole through which the output extraction means of the steering device is passed, and a telescopic bellows portion disposed on both sides of the cylindrical portion. In the resin-made steering boot for the center take-off type steering device, the thickness of the cylindrical portion is increased by making the thickness t ′ of the cylindrical portion larger than the thickness t of the bellows portion .
[0007]
Therefore, even if the central cylindrical portion receives force due to expansion and contraction of the bellows portions on both sides during the steering operation, it is harder to deform because it is stronger than the bellows portion, and in particular, deformation at the periphery of the hole occurs. Difficult to warp. For this reason, there is little possibility that the seal | sticker comprised between the output extraction means of a steering device will be impaired. In addition, by changing the thickness of the parison and the blow method slightly without changing the boot manufacturing equipment, especially the blow mold, etc., it can withstand the force that accompanies the deformation of the bellows and prevents at least the periphery of the hole from deforming. The cylindrical portion can be provided with sufficient strength.
Further, in the steering boot according to claim 1, a flat portion that keeps a good fitting state is formed around a hole provided in the cylindrical portion, and at least a side edge portion of the flat portion extending in the axial direction extends in the radial direction. The projecting shape is protruding. Therefore, since the strength of at least the axial direction of the flat portion increases, even if the cylindrical portion receives a force from the bellows portion that expands and contracts due to the operation of the steering device, the deformation of the flat portion in the axial direction is suppressed and contact with the mounting plate Is maintained, and the cylindrical portion is backed up by the mounting plate to reduce deformation of the flat portion, particularly in the vicinity of the hole. Further, since the flat portion can be positioned by contacting the mounting plate, it is easy to position the output take-out means and the spacer and the hole.
[0009]
Here, the wall thickness t ′ of the cylindrical portion is preferably 2 t or more and 3.5 t or less as in the second aspect of the invention. If it is smaller than 2t, sufficient strength cannot be obtained in the cylindrical portion, and if it is larger than 3.5t, the parison thickness ratio differs greatly between the thick portion and the thin portion, and blow molding becomes difficult. Blow-molding boots with moderate strength that will not bend even when subjected to the expansion and contraction of the bellows, by keeping the wall thickness t 'of the cylindrical part within 2 to 3.5 times the wall thickness of the bellows Can be obtained.
[0012]
According to a third aspect of the present invention, in the steering boot according to the first or second aspect , both ends of the cylindrical portion are further thickened. In this case, the thick end portion is unlikely to be deformed by the reaction force received from the bellows portion, so that the reaction force received from the bellows portion is uniformly dispersed and transmitted to the cylindrical portion, thereby reducing the stress concentration. Further, deformation of the hole periphery is prevented.
[0014]
According to a fourth aspect of the present invention, in the steering boot according to any one of the first to third aspects, a protrusion that comes into contact with a mounting plate for attaching an output extraction means of the steering device is provided on the periphery of the flat portion. In this case, the protrusion functions as a seat surface that comes into contact with the mounting plate substantially uniformly and functions as a rib that reinforces the strength of the flat portion, thereby preventing the flat portion from being distorted or warped.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the configuration of the present invention will be described in detail based on an example of an embodiment shown in the drawings.
[0016]
1 to 4 show an embodiment of the present invention. The steering boot 1 of the present invention is a resin boot for a center take-off type steering device, and includes a cylindrical portion 2 having two holes 5 and 5 through which an output take-out means 11 of the steering device is passed, and the cylindrical portion 2. The bellows portions 4 and 4 are extendable and connected to both sides in the axial direction. Here, the output take-out means 11 of the steering device is an output take-off bolt for attaching the mounting plate 10 to which the steering tie rod is connected to the rack 12 in the steering boot 1, that is, the output from the center of the rack 12 to the steering wheel. It is a means for taking out, and includes a spacer 13 provided between the mounting plate 10 and the rack 12 to facilitate positioning of the rack 12 and the like.
[0017]
The steering boot 1 is formed so that the cylindrical portion 2 has a strength that prevents at least the periphery of the holes 5 and 5 from being deformed when subjected to a reaction force due to deformation of the bellows portions 4 and 4. In the present embodiment, the thickness t ′ of the cylindrical portion 2 is made larger than the thickness t of the bellows portion 4 to improve the strength of the cylindrical portion 2 and prevent deformation of the peripheral portions of the holes 5 and 5. ing.
[0018]
As shown in FIG. 3, the cylindrical portion 2 has a substantially cylindrical shape as a whole, and a flat portion 3 is formed that forms a flat surface or a rectangular frame at a portion facing the mounting plate 10. The flat portion 3 of the cylindrical portion 2 is formed with two holes 5 through which an output take-out bolt as the fastening take-out means 11 is passed. The hole 5 does not have to have a special cross-sectional shape, and may have a cross-sectional shape similar to the conventional one or a special shape.
[0019]
Protrusions 8 that come into contact with the mounting plate 10 are provided on the periphery of the flat portion 3 to reinforce the strength of the flat portion 3. For example, in the present embodiment, a protrusion 8 is formed on the periphery of the flat portion 3 like a rectangular frame, and a seating surface that contacts the mounting plate 10 is formed by the protrusion 8. The reinforcement of the flat portion 3 is not necessarily based on the protrusion 8, and the convex portions 9 and 9 are formed on the side edges extending in the axial direction of the flat portion 3, respectively, so that the strength against twisting in the axial direction of the flat portion 3 is increased. Anyway. The deformation and warpage required in the flat part 3 are mainly caused by the axial force accompanying the expansion and contraction of the bellows part 4, and at least the convex part 9 is provided so that the mounting plate 10 in contact with the convex part 9 In combination, the deformation around the hole 5 can be reduced, but more preferably, the protrusion 8 is formed with reinforcement in the tangential direction of the cylindrical portion 2 orthogonal to the convex portion 9.
[0020]
Therefore, in the present embodiment, as shown in FIG. 2, the protrusion 8 including the above-described convex portion 9 has a rectangular shape surrounding the flat portion 3, and as shown in FIG. 1 and FIG. Is formed on a flat surface so as to be in surface contact with the mounting plate 10. For this reason, the cylindrical part 2 contacts the mounting plate 10 through the protrusions 8 in a distributed state of pressure and receives a backup from the mounting plate 10 to prevent the peripheral portions of the holes 5 and 5 from being warped back. Further, the protrusions 8 formed in a rectangular shape around the flat portion 3 further improve the strength against twisting of the flat portion 3 and the like. Further, as shown in FIG. 4, when sealing is performed by sandwiching between the rigid spacer 13 and the mounting plate 10, the mounting plate 10 can be easily mounted at the position of the hole by the protrusion 8 and the convex portions 9 and 9. . As shown in FIG. 3 or FIG. 4, the spacer 13 interposed between the mounting plate 10 and the rack 12 or between the tubular portion 2 and the rack 12 can further improve the strength against twisting of the flat portion 3. .
[0021]
In the present embodiment, the strength of the tubular portion 2 is also improved by forming the tubular portion 2 thicker than the thickness t of the bellows portion 4. In this case, it is preferable that the thickness t ′ of the cylindrical portion 2 is 2 t or more and 3.5 t or less. If it is smaller than 2t, sufficient strength cannot be obtained, and if it is larger than 3.5t, it becomes difficult to form a steering boot by blow molding.
[0022]
In addition to increasing the thickness t ′ of the tubular portion 2, it is possible to improve the strength by providing the tubular portion 2 with ribs 6. In the present embodiment, the ribs 6 are provided on the outer periphery of the cylindrical portion 2 in a lattice shape to improve the strength. In this case, the strength of the cylindrical portion 2 is strengthened both in the axial direction and in the radial direction, and it does not warp in the axial direction or deform the cross-sectional shape into an irregular shape. However, the rib shape is not limited to this. For example, the rib shape may be provided in an oblique lattice shape, or a plurality of linear ribs may be provided along the axial direction of the steering boot 1. It is also possible to form the rib 6 by projecting to the inner peripheral surface side.
[0023]
Furthermore, it is preferable that end portions (hereinafter referred to as “annular portions”) 7 having a circular cross section as shown in FIG. 1 are formed at both ends of the cylindrical portion 2. As described above, the steering boot 1 has a shape in which the flat portion 3 is provided on the substantially cylindrical tubular portion 2, but by providing such an annular portion 7, the tubular portion 2 is formed. The reaction force from the bellows portion 4 to be received is uniformly dispersed, and the stress concentration in the peripheral portions of the holes 5 and 5 can be reduced. In the present embodiment, as shown in FIG. 1, annular portions 7 are provided at both ends in the axial direction of the cylindrical portion 2 to disperse reaction forces from the bellows portions 4 and 4.
[0024]
On the other hand, the shape of the bellows parts 4 and 4 is not particularly limited, and a known bellows shape as required or a bellows shape as shown in FIG. 1 can be adopted. Here, the thickness t of the bellows portion referred to in this specification refers to the thickness of the peak portion in the region excluding the mounting portion to the counterpart member.
[0025]
The steering boot 1 formed as described above is stronger than the bellows portion 4 even when the central cylindrical portion 2 receives force due to expansion and contraction of the bellows portions 4 on both sides during the steering operation. It is difficult to be deformed, and in particular, deformation at the peripheral portion of the hole 5 is difficult to occur and no warping occurs. For this reason, there is little possibility that the seal | sticker comprised between the output extraction means 11 of a steering device will be impaired. Moreover, when the thickness t ′ of the cylindrical portion 2 is increased by making the thickness t ′ of the cylindrical portion 2 larger than the thickness t of the bellows portion 4, the thickness t ′ of the cylindrical portion 2 is particularly increased. When the thickness t of the portion 4 is not less than 2 times and not more than 3.5 times, the cylindrical portion 2 is hardly deformed by application of normal blow molding, and the sealing performance of the hole 5 through which the output extraction means 11 is passed is improved. Boots can be manufactured.
[0026]
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.
[0027]
For example, in this embodiment, in addition to making the thickness t ′ of the cylindrical portion 2 thicker than the thickness t of the bellows portion 4, providing the annular portion 7 at the end of the cylindrical portion 2, ribs 6, forming the flat portion 3, and forming the convex portion 9 on the flat portion 3 or forming the protrusions 8 at the same time, but is not particularly limited to this. Any means can be selected or combined.
[0028]
【The invention's effect】
As is apparent from the above description, according to the steering boot of claim 1 , the strength of the tubular portion is increased by making the thickness t ′ of the tubular portion thicker than the thickness t of the bellows portion. Therefore, even if the central cylindrical portion receives force due to expansion and contraction of the bellows portions on both sides during the steering operation, it is less likely to be deformed because it is stronger than the bellows portion, and is particularly difficult to deform around the hole. Since no warping or the like occurs, there is little possibility that the seal formed between the output take-out means of the steering device is damaged. In addition, by changing the thickness of the parison and the blow method slightly without changing the boot manufacturing equipment, especially the blow mold, etc., it can withstand the force that accompanies the deformation of the bellows and prevents at least the periphery of the hole from deforming. The cylindrical portion can be provided with sufficient strength.
[0029]
In particular, as in the second aspect of the invention, the thickness t ′ of the cylindrical portion is set to be not less than 2 times and not more than 3.5 times the thickness of the bellows portion, thereby receiving the force when the bellows portion is expanded and contracted. However, it is possible to obtain a boot having an appropriate strength that does not bend by blow molding.
In the steering boot according to claim 1, a flat portion that maintains a good fitting state is formed around the hole provided in the cylindrical portion, and at least a side edge portion of the flat portion that extends in the axial direction extends in the radial direction. Since the protruding convex shape increases the strength of at least the axial direction of the flat part, even if the cylindrical part receives a force from the bellows part that expands and contracts due to the operation of the steering device, the deformation of the flat part in the axial direction is suppressed. Thus, contact with the mounting plate is maintained, and the cylindrical portion is backed up by the mounting plate to reduce deformation in the flat portion, particularly in the vicinity of the hole. Further, since the flat portion can be positioned by contacting the mounting plate, it is easy to position the output take-out means and the spacer and the hole.
[0032]
Furthermore, according to the steering boot according to claim 3 , since the thick end portion is unlikely to be deformed by the reaction force received from the bellows portion, the reaction force received from the bellows portion is uniformly distributed and transmitted to the cylindrical portion, Reduce stress concentration.
[0034]
According to the steering boot of claim 4 , since the protrusion functions as a rib for reinforcing the strength of the flat portion, it is possible to prevent the flat portion from being warped and warped, and to prevent the warp and deformation around the hole and to provide a sealing property. Can be held.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a steering boot showing an embodiment of the present invention.
FIG. 2 is a partial plan view showing a shape of a cylindrical portion of the steering boot.
FIGS. 3A and 3B are partial views showing a peripheral structure of a steering boot hole and output take-out means; FIG. 3A is a cross-sectional view seen from the side of a cylindrical portion, and FIG. 3B is a cross-sectional view seen from the axial direction;
FIGS. 4A and 4B are partial views showing a peripheral structure of a steering boot hole and output take-out means according to another embodiment of the present invention, wherein FIG. 4A is a cross-sectional view seen from the side of a cylindrical portion, and FIG. It is sectional drawing.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Steering boot 2 Cylindrical part 3 Flat part 4 Bellows part 5 Hole 6 Rib 7 Ring part (circular edge part of a cylindrical part)
8 Projection 9 Convex shape (convex part)
10 Mounting plate 11 Output extraction means

Claims (4)

In the resin-made steering boot for a center take-off type steering device, the tubular portion includes a cylindrical portion having a hole through which an output take-out means of the steering device passes, and an expandable bellows portion disposed on both sides of the cylindrical portion. And a flat portion that keeps a good fitting state around the hole provided in the tubular portion, and has at least a shaft of the flat portion. A resin-made steering boot for a center take-off type steering device, characterized in that a side edge portion extending in a direction is a convex shape protruding in a radial direction .   The resin steering boot for a center take-off type steering apparatus according to claim 1, wherein a thickness t 'of the cylindrical portion is 2t or more and 3.5t or less.   3. The resin steering boot for a center take-off type steering apparatus according to claim 1, wherein both ends of the tubular portion are thicker. 4. A resin steering boot for a center take-off type steering apparatus according to any one of claims 1 to 3 , wherein a protrusion that contacts an attachment plate for attaching an output take-out means of the steering apparatus is provided on the periphery of the flat portion. .

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