JP6826391B2 - Dust cover and ball joint - Google Patents

Description

The present invention relates to a tubular dust cover attached between a stud portion of a ball stud and a housing along the vertical direction in the axial direction, and a ball joint provided with the tubular dust cover.

Conventionally, in order to protect a ball joint used for a suspension device of a vehicle such as an automobile from flying stones and muddy water, a tubular dust cover made of synthetic resin or rubber is used. The dust cover is attached between the housing and a mating member (such as a knuckle arm) to which the stud portion of the ball stud is attached. In this dust cover, for example, a lip portion is set on the inner edge of the opening on one end side that is in sliding contact with the stud portion of the ball stud in order to ensure the followability and adhesion to the swing of the ball stud. (See, for example, Patent Document 1.).

Since the environment in which the ball joint is used varies, the opening side of the dust cover may fall downward due to icing in cold regions and a decrease in binding force due to aging (deterioration of material), and the sealability may be maintained. It can be difficult. As a countermeasure, for example, a reinforcing ring embedded in the opening of the dust cover (see, for example, Patent Document 2), a backup ring in which the reinforcing ring is embedded in the opening of the dust cover and the vicinity of the opening is supported from below. Those provided (see, for example, Patent Document 3) or those provided with a convex portion for preventing a drop (see, for example, Patent Document 4) are known.

Japanese Unexamined Patent Publication No. 62-13408 (Page 2, Fig. 1-2) JP-A-2009-14064 (Page 5-6, FIG. 1) Registered Utility Model No. 253348 (Pages 2-3, Fig. 1) Jikkenhei 5-19633 (pages 7-8, FIG. 1)

However, in the case of each of the configurations of Patent Documents 2 to 4 described above, all of them may cause an increase in the cost of the dust cover and may affect the swing of the ball stud. Then, such a problem occurs not only in the dust cover of the ball joint for a vehicle but also in the dust cover of the ball joint used at an arbitrary place.

The present invention has been made in view of these points, and provides a dust cover capable of suppressing a drop in the upper side while suppressing an influence on the swing of a ball stud at low cost, and a ball joint provided with the dust cover. The purpose is.

The dust cover according to claim 1 includes the stud portion of a ball stud having a ball portion and a stud portion protruding from the ball portion and fixed to a mating member, and a housing for rotatably holding the ball portion. It is a tubular dust cover that is attached along the vertical direction in the axial direction between the two, and it protrudes along the axial direction and the tip side is on the outer surface of the stud portion by elastic force without using a separate member. The lip portion includes a lip portion to be pressure-welded, and the lip portion has a first surface that is inclined upward at a predetermined positive value toward the direction away from the stud portion with respect to the axial direction. It is located on the lower side with respect to the first surface, and is inclined downward in a direction away from the stud portion with respect to the axial direction at a predetermined second angle smaller than the first angle. It has a second surface, and the second angle of the second surface is set to a negative value .

Ball joint請Motomeko 2 described, a ball stud having a stud portion which is fixed to the ball portion and the mating member protruding from the ball portion, a housing for holding the ball portion rotatably, the ball is obtained by and a dust cover according to claim 1, wherein attached to and along the axial direction in the vertical direction over between the stud portion of the stud and the housing.

According to the dust cover according to the first aspect, with respect to this first surface rather than the first angle which is the inclination angle of the upper first surface of the lip portion which repeatedly deforms and returns due to the swing of the stud portion. the second angle is rather small the inclination angle of the second surface located on the lower Te, a second angle inclination of the second surface minus value to the lower side facing away from the second stud portion By doing so, the upward frictional force with respect to the outer surface of the stud portion becomes smaller than the downward frictional force generated by the first and second surfaces, and the upper side of the dust cover is in the direction opposite to the dip direction. Since the propulsive force is generated, the downward depression of the upper side can be suppressed without using a separate member. Therefore, at low cost, it is possible to suppress the depression of the upper side while suppressing the influence on the swing of the ball stud.

請According to Motomeko 2 ball joint according, by providing the dust cover of claim 1, wherein, for example, to maintain the sealability with suppressed upper drop of the dust cover due to aging for a long time, reliability The sex can be secured.

(a) is an enlarged cross-sectional view showing the upper side of the dust cover of one related technique of the present invention, and (b) is an explanatory view schematically showing the shape of the lip portion. It is a side view which shows the ball joint provided with the dust cover by cutting out a part. (a) is a cross-sectional view, (b) is an explanatory view showing the shape of the lip portion schematically showing an enlarged upper dust cover of one embodiment of the present invention.

Hereinafter, the configuration of one related technique of the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 2, reference numeral 11 denotes a ball joint, and the ball joint 11 is used for a vehicle such as an automobile. The ball joint 11 is a so-called lower ball joint that movably connects the knuckle arm 12 as a mating member (attached portion) on the steering wheel (front wheel) side, which is a wheel (not shown), and the lower arm. The ball joint 11 has a socket 16 which is a housing (receiving side member), a ball stud 17 which is a ball side member, and a dust cover 18 attached between the knuckle arm 12 and the socket 16. I have. Further, the ball joint 11 may include, for example, a substantially cylindrical ball sheet 19 which is a bearing sheet that holds a part of the ball stud 17 slidably (rotatably) and is housed in the socket 16. .. Hereinafter, the lower side in the drawing will be described as a lower side which is one end side, and the upper side will be described as an upper side which is the other end side.

The knuckle arm 12 is formed of, for example, a rigid metal, is connected to the steering wheel via a hub (not shown), and is connected to the steering device via a tie rod (not shown).

The socket 16 is made of metal formed into a bottomed cylinder (covered cylinder) by, for example, (cold) forging or casting. Inside the socket 16, an inner chamber 21, which is an accommodating portion, is partitioned. Further, a socket opening 22 which is a housing opening for communicating the inner chamber 21 and the outside of the socket 16 is opened at the upper end of the socket 16. Further, a cover mounting portion 23 for mounting and fixing the upper end portion of the dust cover 18 is formed on the outer peripheral portion on the upper end side of the socket 16. The socket 16 may be formed into a bottomed cylinder by closing the lower end of the housing body (socket body) formed in a cylindrical shape with a closing member (plug), or may be formed into a bottomed cylinder in advance. You may be.

The ball stud 17 is made of steel, for example, and integrally includes a spherical ball portion 25 and a shaft-shaped stud portion 26 connected to the ball portion 25.

A part of the outer peripheral surface of the ball portion 25 is slidably (rotated) held by the ball sheet 19 via a lubricant (grease). That is, the ball portion 25 is housed in the inner chamber 21 of the socket 16 together with the ball sheet 19.

The stud portion 26 is a portion attached to the external knuckle arm 12 to which a load is applied. The stud portion 26 projects outward (upward) from the socket 16. Further, the stud portion 26 is fixed by a fixing member 28 such as a nut in a state of being inserted into the knuckle arm 12. Therefore, for example, a screw portion 29 as a fastening portion to be fastened to the fixing member 28 is provided on the tip end side of the stud portion 26.

The dust cover 18 is also called a dust seal or a boot, and covers the socket opening 22 of the socket 16 regardless of the swing of the ball stud 17, and keeps moisture and dust inside the socket 16 or the ball sheet 19. It prevents invasion. The dust cover 18 is formed in a substantially cylindrical shape by an elastic member such as synthetic resin or rubber. Further, the dust cover 18 is arranged along the vertical direction in the axial direction. Further, in the present related technology , the dust cover 18 has a flat shape having a larger diameter than the vertical dimension, which is the axial dimension. Further, the dust cover 18 includes an upper, in the related art upper side is brought into close contact with the outer peripheral surface 26a and the knuckle arm 12 is the outer surface of the stud portion 26 of the ball stud 17, on the lower side, the related art lower end socket 16 at Be in close contact. Further, a first opening 31 is opened at the upper end of the dust cover 18 facing the knuckle arm 12. Further, a second opening 32 is opened at the lower end of the dust cover 18. Further, the vertical intermediate portion of the dust cover 18 is a bulging portion 33 that bulges in the radial direction. That is, the dust cover 18 is formed in a bell shape or a spindle shape. A first mounting portion 34 is provided on the upper side of the dust cover 18, or on the upper end side in the present related technology . Further, a second mounting portion 35 is provided on the lower side of the dust cover 18 and on the lower end side in this related technology . Further, a contact portion 36 is provided at the upper end portion of the dust cover 18. Further, a lip portion 37 is provided on the upper side of the dust cover 18 and on the upper end side in this related technology .

The first opening 31 is an opening through which the stud portion 26 of the ball stud 17 is inserted in the related technology . Therefore, in the present related art , the first opening 31 is a small diameter side opening having an opening diameter smaller than that of the second opening 32, and the second opening 32 is a large diameter side opening. It has become.

The first mounting portion 34 is mounted on the knuckle arm 12 and the socket 16 located relatively on the upper side. In the present art , the first mounting portion 34 is brought into close contact with the outer peripheral surface 26a of the stud portion 26 of the ball stud 17 and the knuckle arm 12.

The second attachment portion 35 is attached to the knuckle arm 12 and the socket 16 located relatively lower. In the related art , the second mounting portion 35 is fitted to the cover mounting portion 23 of the socket 16. The second mounting portion 35 is fastened and fixed to the cover mounting portion 23 by, for example, a ring-shaped fixing ring 39.

The contact portion 36 is located on the upper end surface of the dust cover 18. That is, the contact portion 36 is provided in the first mounting portion 34 in the present related technology . For example, in the present related technology , the contact portion 36 is provided in a plane shape along the axial direction (orthogonal direction) D of the dust cover 18, but is provided in a lip shape that protrudes upward, for example. May be good.

The lip portion 37 is provided in the first mounting portion 34 in the present related technology . The lip portion 37 projects along the axial direction D of the dust cover 18. That is, the lip portion 37 projects toward the central axis of the dust cover 18. Further, the lip portion 37 includes a first surface 41, a second surface 42, and a sliding contact surface 43. The lip portion 37 may be provided in only one stage, or may be provided in a plurality of stages above and below. In the present related technology , the lip portion 37 is provided in two stages, for example, upper and lower.

As shown in FIG. 1A, the first surface 41 is a surface forming the upper side of the lip portion 37. As shown in FIG. 1 (b), the first surface 41 faces upward in the direction (diameter direction) away from the stud portion 26 (central axis of the dust cover 18) with respect to the axial direction D of the dust cover 18. It is tilted at the first angle α.

As shown in FIG. 1A, the second surface 42 is a surface forming the lower side of the lip portion 37. That is, the second surface 42 is located below the first surface 41, or on the socket 16 side in the related art . Then, as shown in FIG. 1 (b), the second surface 42 is in a direction (diameter direction) away from the stud portion 26 (central axis of the dust cover 18) with respect to the axial direction D of the dust cover 18. It is inclined to the lower side at a predetermined second angle β.

Then, in the lip portion 37, the first angle α of the first surface 41 is a predetermined positive value (α> 0), and the second angle β of the second surface 42 is larger than the first angle α. It is set to a small predetermined value (α> β). In this related technique , the second angle β is set to a positive value (α>β> 0). When the lip portions 37 are provided in a plurality of stages above and below as in the related technology , the first angles α and the first angles α of all or any one or more of the lip portions 37 are provided. Any angle β of 2 may satisfy the above relationship.

The sliding contact surface 43 shown in FIG. 1A is a surface that is pressed against the outer peripheral surface 26a of the stud portion 26 of the ball stud 17. The sliding contact surface 43 may be, for example, a continuous cylindrical surface between the first surface 41 and the second surface 42, as long as it is pressure-contacted with the outer peripheral surface 26a of the stud portion 26 of the ball stud 17. The shape may be such that it projects in an arc shape in a cross section from a position continuous with the surface 41 and the second surface 42 toward the outer peripheral surface 26a of the stud portion 26.

Further, the ball sheet 19 shown in FIG. 2 is formed in a substantially cylindrical shape, for example, made of synthetic resin having excellent wear resistance, and is fitted and held in the inner chamber 21 of the socket 16. Inside the ball sheet 19, a spherical sliding contact surface portion 45 that rotatably holds the ball portion 25 is formed.

Next, the assembly operation of the above-mentioned one related technique will be described with reference to the drawings.

First, a separately molded ball portion 25 is press-fitted into the ball sheet 19 previously formed by injection molding using a molding die (mold) (not shown). The stud portion 26 may be integrally formed with the ball portion 25, or may be later connected to the ball portion 25 by welding or the like. Then, the ball sheet 19 holding the ball portion 25 is press-fitted into the inner chamber 21 of the socket 16 separately formed by forging or casting.

After that, the dust cover 18 is inserted into the stud portion 26 of the ball stud 17, and the second attachment portion 35 on the lower end side of the dust cover 18 is tightened and fixed to the cover attachment portion 23 by the fixing ring 39, and the dust is fixed. The ball joint 11 is completed by fixing the first mounting portion 34 on the upper side of the cover 18 to the outer peripheral surface 26a of the stud portion 26 of the ball stud 17.

In this state, the dust cover 18 is compressed in the axial direction, so that the contact portion 36 of the first mounting portion 34 is pressed against the lower surface of the knuckle arm 12 by the elastic force in the axial direction, and the first and second As the mounting portions 34 and 35 are expanded in the axial direction D, the sliding contact surface 43 on the tip side of the lip portion 37 of the first mounting portion 34 is a stud of the ball stud 17 due to the elastic force in the axial direction D. The outer peripheral surface 26a of the portion 26 is pressure-welded, and the second mounting portion 35 is pressure-welded and held by the cover mounting portion 23 of the socket 16.

In the ball joint 11 formed in this way, when a load from the vehicle body side is applied to the ball stud 17, the ball portion 25 held by the sliding contact surface portion 45 of the ball seat 19 smoothly rotates (slides). The ball stud 17 swings back and forth and left and right. Since the lip portion 37 is pressed against the outer peripheral surface 26a of the stud portion 26, the dust cover 18 repeatedly deforms (deflects) and returns (extends) due to the swing of the stud portion 26. For example, in FIG. 1A, when the ball stud 17 swings to the left, the first surface 41 side of the lip portion 37 that deforms following the outer peripheral surface 26a of the stud portion 26 is in sliding contact with the outer peripheral surface 26a. When the ball stud 17 swings to the right due to frictional force, the second surface 42 side of the lip portion 37 that deforms following the outer peripheral surface 26a of the stud portion 26 slides in contact with the outer peripheral surface 26a and rubs. Generate force. At this time, since the inclinations of the first surface 41 and the second surface 42 of the lip portion 37 are different, the frictional force generated on the outer peripheral surface 26a of the stud portion 26 when the lip portion 37 is deformed and when the lip portion 37 is returned is generated. Is different.

Specifically, in the present related technology , a second surface located below the first surface 41, which is an inclination angle of the first surface 41 located above the lip portion 37, is located below the first angle α. Since the second angle β, which is the inclination angle of the surface 42, is small, the stud portion 26 is directed upward from the downward frictional force generated by the first and second surfaces 41 and 42 with respect to the outer peripheral surface 26a. The frictional force becomes smaller. For this reason, a propulsive force is generated on the upper side (upper end side) of the dust cover 18 in the upward direction, in other words, in the direction opposite to the dip direction. It can be suppressed without using a member such as. Therefore, at low cost, it is possible to suppress the depression of the upper side (upper end side) while suppressing the influence of the ball stud 17 on the swing.

Moreover, since the lip portion 37 is located on the upper side (upper end side) of the dust cover 18, the moisture that tries to enter the inside of the dust cover 18 from the outside does not easily collect on the upper part of the dust cover 18, and the moisture enters the inside. Can be made more difficult to invade, and airtightness can be ensured.

As a result, it is possible to suppress the separation of the upper end side (contact portion 36) of the dust cover 18 from the knuckle arm 12 due to aged deterioration (deterioration of the material), etc., and the sealability can be maintained for a long period of time, reliability. It is possible to provide a ball joint 11 that secures the above.

In the above-mentioned one related technique , the second angle β of the second surface 42 may be set to 0 or less (α> 0 ≧ β). More preferably, the second angle β of the second surface 42 may be set to a negative value as in one embodiment shown in FIGS. 3 (a) and 3 (b) (α> 0). > Β). That is, the second surface 42 is inclined downward with an angle of 0 or a negative value toward the direction away from the stud portion 26 (the central axis of the dust cover 18), in other words, substantially parallel to the axial direction D or axially linear. It may be formed so as to incline upward with respect to the direction D. In this case, the frictional force generated by the second surface 42 with respect to the outer peripheral surface 26a of the stud portion 26 becomes larger downward than above, which is opposite to the dip direction generated on the upper side (upper end side) of the dust cover 18. Since the propulsive force in the direction can be made larger, the downward depression of the upper side (upper end side) can be more reliably suppressed without using a member such as a separate reinforcing ring.

In the above-mentioned one related technique and one embodiment, the ball joint 11 is arranged with the socket 16 on the lower side and the stud portion 26 connected to the mating member (knuckle arm 12) on the upper side. The ball joint 11 may be arranged with the stud portion 26 on the upper side and the stud portion 26 on the lower side. In this case, for example, the lip portion 37 and the contact portion 36 are provided on the second mounting portion 35 located on the upper side (upper end side) of the dust cover 18, and the tip end side of the lip portion 37 is the stud portion 26 of the ball stud 17. By making the contact portion 36 press-contact with the outer peripheral surface 26a and press-contact the contact portion 36 with respect to the lower end portion of the socket 16 from below, it is possible to obtain the same effects as those of the above-mentioned one related technique and one embodiment. ..

Therefore, the ball joint 11 of the above-mentioned one related technique and one embodiment is appropriately used not only for a vehicle suspension device but also for any other device such as a steering device in which the axial direction of the dust cover 18 is arranged along the vertical direction. Can be used.

The present invention can be suitably used for, for example, a suspension device for a vehicle such as an automobile.

11 ball joint
12 Knuckle arm as a mating member
16 housing socket
17 ball stud
18 Dust cover
25 ball part
26 Stud part
26a Outer outer surface
37 Lip part
41 First side
42 Second surface D Axis perpendicular direction α First angle β Second angle

Claims (2)

The axial direction is moved up and down between the ball portion and the stud portion of the ball stud provided with the stud portion protruding from the ball portion and fixed to the mating member, and the housing that rotatably holds the ball portion. A tubular dust cover that can be attached along the direction.
The outer surface of the stud portion is provided with a lip portion that protrudes along the axial direction and whose tip side is pressure-welded by elastic force without using a separate member.
The lip part
A first surface that is inclined upward at a predetermined positive value toward the direction away from the stud portion with respect to the axial direction, and a first surface.
It is located on the lower side with respect to the first surface, and is inclined downward in a direction away from the stud portion with respect to the axial direction at a predetermined second angle smaller than the first angle. and a second surface,
A dust cover characterized in that the second angle of the second surface is set to a negative value . A ball stud having a ball portion and a stud portion protruding from the ball portion and fixed to a mating member,
A housing that rotatably holds the ball portion and
The ball joint according to claim 1 , further comprising a dust cover according to claim 1, which is attached between the stud portion of the ball stud and the housing along the axial direction in the vertical direction.

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