JP2009210076A - Dust cover - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dust cover capable of restraining separation of painting on a housing surface of a shock absorber. <P>SOLUTION: Since the lowest end part of the dust cover 1 is constituted in a tapered shape of expanding an inner diameter for separating from a stopper holding part 22, a position of a connecting part P1 between a tapered straight line part 27c and a second circular arc part 27b in a lower end part in the suspending direction of a cylindrical part 24, can be retreated to the outer peripheral surface 24c side by that extent. Thus, even when the lower end part in the suspending direction of the dust cover 1 rocks longitudinally and laterally by vibration when a vehicle travels, the connecting part P1 can be restrained from interfering with a cylinder 5, and as a result of it, the separation of the painting of the cylinder 5 can be restrained. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a dust cover, and more particularly, to a dust cover that can suppress peeling of paint on a housing surface of a shock absorber.

In automobile suspension mechanisms, oil-type shock absorbers using liquid viscous resistance are used for the purpose of damping vibrations due to spring elasticity of the suspension system. A dust cover is attached to the shock absorber. The dust cover is formed from a rubber-like elastic body into a cylindrical shape, and by surrounding the outer periphery of the piston rod and the housing with such a cylindrical body, the oil seal part malfunctions due to adhesion of foreign matters such as dust, stepping stones, etc. Damage to the surface of the piston rod due to can be suppressed.
JP 11-325160 A JP 2003-56634 A Japanese Utility Model Publication No. 05-052396

  However, in the conventional dust cover described above, the upper end of the dust cover is held on the bottom surface of the vibration isolator and the cylindrical body is suspended from its holding position by its own weight. Swings back and forth and left and right. For this reason, the lower end of the oscillating dust cover interferes with the housing of the shock absorber, and the coating on the housing surface is peeled off.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a dust cover that can suppress peeling of paint on the housing surface of a shock absorber.

  In order to achieve this object, the dust cover according to claim 1 is a suspension in which a shock absorber housing is connected to a wheel side and a piston rod of the shock absorber is connected to a vehicle body frame side via a vibration isolator. It is attached to the mechanism and is composed of a rubber-like elastic body, and surrounds the outer periphery of the main body portion attached to the vibration isolator, the piston rod of the shock absorber and the housing hanging downward from the main body portion. A cylindrical cover portion, and the cover portion includes a bellows portion connected to the main body portion and configured in a bellows shape, and a cylindrical portion connected to the bellows portion and configured in a cylindrical shape, The cylindrical portion is on the inner peripheral surface side of the cylindrical portion and is located at the lower end portion in the hanging direction, and the taper whose inner diameter increases as the distance from the main body portion increases. And a configured tapered surfaces.

  According to a second aspect of the present invention, in the dust cover according to the first aspect, the cylindrical portion is configured as a protrusion that protrudes radially inward from the inner peripheral surface of the cylindrical portion and continues in the circumferential direction. A lip portion is provided, and the tapered surface is formed by one side surface of the lip portion, and the inner diameter at the end of the tapered surface is configured to be larger than the inner diameter of the inner peripheral surface of the cylindrical portion.

  The dust cover according to claim 3 is the dust cover according to claim 2, wherein the tapered surface is configured in a straight line in a cross-sectional view including the axis of the cylindrical portion, and the tip portion of the lip portion is the tip portion. It is configured to be curved in a convex arc shape in the axial direction of the cylindrical portion.

  The dust cover according to claim 4 is the dust cover according to claim 2 or 3, wherein the cylindrical portion includes a connecting surface that connects an outer peripheral surface of the cylindrical portion and the tapered surface, and the connecting surface; The crossing angle formed with the outer peripheral surface is configured to be larger than the crossing angle formed between the virtual line extending the tapered surface and the outer peripheral surface in a cross-sectional view including the axial center of the cylindrical portion. Yes.

  According to the dust cover of the first aspect, when the suspension cover is mounted, the main body is attached to the vibration isolator, and the cylindrical cover is suspended downward from the main body. Thus, the piston rod of the shock absorber and the outer periphery of the housing are surrounded by the cover portion. As a result, adhesion of foreign matters such as dust and collision with stepping stones can be suppressed, and the occurrence of malfunction of the oil seal portion and the occurrence of damage to the piston rod surface can be suppressed.

  In this case, according to the present invention, the cylindrical portion includes a tapered surface located on the inner peripheral surface side of the cylindrical portion and at the lower end portion in the hanging direction, and the tapered surface has an inner diameter that increases as the distance from the main body portion increases. Therefore, the position of the inner peripheral surface at the lower end portion in the hanging direction of the cylindrical portion can be retreated to the outer peripheral surface side accordingly.

  Therefore, even when the lower end of the cylindrical portion swings forward, backward, left and right due to vibration during traveling of the vehicle, the inner peripheral surface of the lower end of the swinging cylindrical portion interferes with the shock absorber housing. As a result, it is possible to suppress peeling of the coating on the housing surface.

  According to the dust cover of claim 2, in addition to the effect of the dust cover of claim 1, the cylindrical portion protrudes radially inward from the inner peripheral surface of the cylindrical portion and continues in the circumferential direction. Since the lip portion configured as described above is provided, the inner peripheral surface at the lower end portion in the hanging direction of the cylindrical portion can be prevented from sticking to the housing surface of the shock absorber.

  For example, in the case of a bellows-like bellows portion in which peaks and valleys are alternately arranged, even if it interferes with the housing surface of the shock absorber, the contact area is small, so that the bellows portion sticks to the housing surface. It is hard to do. However, when the cylindrical part is configured in a cylindrical shape, durability can be improved and the protection effect of the shock absorber can be improved, while the inner peripheral surface of the lower end of the hanging direction interferes with the housing surface of the shock absorber. Since the contact area is large, it is easy to stick to the housing surface especially when the inner peripheral surface is wet.

  When this sticking occurs, the housing surface is rubbed by the inner peripheral surface of the dust cover (cylindrical portion) with the expansion and contraction of the shock absorber during traveling, and the paint peels off. Also, as the shock absorber expands and contracts, the dust cover itself is also greatly deformed, causing cracks in the deformed and bent parts, resulting in a decrease in durability, and bending with deformation In this state, the initial shape cannot be maintained, so that the exposure of the shock absorber is increased and the protection function is deteriorated.

  On the other hand, according to the present invention, since the lip portion is provided so as to project radially inward from the inner peripheral surface of the cylindrical portion, the inner peripheral surface of the cylindrical portion interferes with the housing surface of the shock absorber. Even in this case, by bringing the lip portion into contact with the housing surface, the contact area where the inner peripheral surface of the cylindrical portion contacts the housing surface can be reduced, and as a result, the inner peripheral surface of the cylindrical portion sticks to the housing surface. This can be suppressed.

  Moreover, since this lip | rip part is comprised as a protrusion continuous in the circumferential direction, even if a dust cover (cylindrical part) rocks | fluctuates in any direction of front and rear, right and left by the vibration during driving | running | working of a vehicle, this lip | rip part Can be reliably brought into contact with the housing surface of the shock absorber. Accordingly, there is an effect that the inner peripheral surface of the cylindrical portion can be reliably suppressed from sticking to the housing surface.

  Furthermore, as described above, the lip portion is configured as a continuous ridge in the circumferential direction, so that the strength of the lip portion is ensured compared to the configuration in which the lip portion is intermittently disposed in the circumferential direction. Further, it is possible to suppress damage to the lip portion due to contact with the housing surface of the shock absorber. As a result, the durability can be improved and the effect of suppressing sticking can be maintained.

  In addition, as described above, the lip portion is configured as a continuous protrusion in the circumferential direction, so that the lip portion is removed from the vulcanization mold as compared with the configuration in which the lip portion is intermittently disposed in the circumferential direction. Therefore, the yield can be improved by suppressing the chipping of the lip portion during mold removal.

  Here, according to the present invention, since the tapered surface is formed by one side surface of the lip portion, the durability and the yield are improved as compared with the case where the tapered surface and the lip portion are positioned apart from each other. There is an effect that it can be improved.

  That is, when the taper surface and the lip portion are positioned apart from each other, the portion where the taper surface is formed becomes a thin film, and the strength is reduced. For this reason, when the vehicle is swung back and forth and left and right due to vibrations while the vehicle is running, some of the chips are cracked or cracked, resulting in a decrease in durability. Similarly, even when demolding from the vulcanizing mold, chipping and cracking occur due to a decrease in strength, leading to a decrease in yield.

  On the other hand, according to the present invention, the tapered surface is formed by one side surface of the lip portion, that is, the tapered surface and the lip portion are integrated. Can be reinforced by the lip portion, and accordingly, the strength can be secured and the occurrence of chips and cracks can be suppressed. As a result, durability and yield can be improved.

  In addition, as described above, by forming the tapered surface by one side surface of the lip portion, the lip portion can be positioned on the inner peripheral surface at the lower end portion in the hanging direction of the cylindrical portion. In other words, the dust cover (cylindrical portion) swings back and forth and left and right due to vibration during traveling of the vehicle, and the lip portion can be disposed at a position where it is most likely to stick to the housing surface of the shock absorber. As a result, as described above, there is an effect that it is possible to effectively suppress the inner peripheral surface of the cylindrical portion from sticking to the housing surface while improving the durability and the yield.

  Furthermore, according to the present invention, since the inner diameter at the end of the tapered surface is larger than the inner diameter of the inner peripheral surface of the cylindrical portion, the position of the inner peripheral surface at the lower end in the hanging direction of the cylindrical portion is set to the outer peripheral surface. Can be fully retracted to the side. Therefore, even when the lower end in the hanging direction of the cylindrical portion swings back and forth and left and right due to vibration during running of the vehicle, the inner peripheral surface (tapered surface) at the lower end in the hanging direction of the swung cylindrical portion is the housing of the shock absorber. Can be reliably suppressed, and as a result, it is possible to suppress peeling of the coating on the housing surface.

  According to the dust cover of the third aspect, in addition to the effect produced by the dust cover of the second aspect, the taper surface is configured linearly in a cross-sectional view including the axial center of the cylindrical portion. Interference between the inner peripheral surface at the lower end and the housing surface of the shock absorber can be suppressed, and in the event of interference, the linear taper surface makes full contact with the housing surface, reducing contact pressure. There is an effect that it is possible to suppress peeling of the paint on the housing surface.

  On the other hand, as described above, the lip portion is a portion for suppressing the inner peripheral surface of the cylindrical portion from sticking to the housing surface of the shock absorber. This is a part for reducing the contact area between the inner peripheral surface and the housing surface. Therefore, if the shape of the lip is linear in a cross-sectional view including the axial center of the cylindrical portion, the effect of reducing the contact area described above when contacting the housing surface is reduced, and the cylindrical portion is reduced. In addition to incurring a problem that the inner peripheral surface of the lip sticks to the housing surface, the lip portion itself contacts the entire surface and sticks to the housing surface.

  On the other hand, according to the present invention, since the tip end portion of the lip portion is configured to be curved in a convex arc shape in the axial direction of the cylindrical portion, the lip portion curved in the arc shape comes into contact with the housing surface. Thereby, a contact area can be made small and it can suppress that the internal peripheral surface in the drooping direction lower end part of a cylindrical part sticks to the housing surface.

  In addition, if the tip of the lip portion is curved in the shape of a convex arc in the axial direction of the cylindrical portion in this way, for example, the lower end in the hanging direction of the cylindrical portion swung by vibration during traveling of the vehicle Even if the inner peripheral surface of the part strongly collides with the housing of the shock absorber, the lip part itself can be caused to collide gently by being deformed, so that peeling of the coating on the housing surface can be suppressed. effective.

  According to the dust cover of the fourth aspect, in addition to the effect produced by the dust cover according to the second or third aspect, the cylindrical portion includes a connection surface that connects the outer peripheral surface of the cylindrical portion and the tapered surface, The crossing angle formed between the connecting surface and the outer peripheral surface is configured to be larger than the crossing angle formed between the virtual line extending the tapered surface and the outer peripheral surface in a cross-sectional view including the axial center of the cylindrical portion. Therefore, there is an effect that it is possible to secure the thickness dimension of the lower end part in the hanging direction of the cylindrical part, that is, the thickness dimension of the end part where the tapered surface is formed, and to improve the yield.

  That is, in a configuration in which the outer peripheral surface and the tapered surface are not directly connected to each other and the outer peripheral surface and the tapered surface are directly connected, the connecting portion between the outer peripheral surface and the tapered surface is thin (in cross-sectional view). Sharp shape). On the other hand, even if the connecting surface is provided between the outer peripheral surface of the cylindrical portion and the tapered surface, the intersection angle between the connecting surface and the outer peripheral surface is an intersection between the virtual line extending the tapered surface and the outer peripheral surface. Similarly, if the angle is smaller than the angle, the outer peripheral surface, the connecting surface, and the connecting portion are thin (a sharp shape in a sectional view).

  Therefore, at the time of demolding from the vulcanization mold, molding failure such as chipping is likely to occur in the above-mentioned connecting portion that is thin, and the yield is reduced. In addition, even if there is no molding failure such as chipping when removing from the vulcanizing mold, if there is a part that is thin (acute angle in cross-sectional view), damage such as chipping after mounting on the vehicle This is likely to occur, and the damaged part is the starting point, causing a problem that the crack progresses.

  On the other hand, according to the present invention, a connecting surface is provided between the outer peripheral surface and the tapered surface, and the intersecting angle of the tapered surface and the connecting surface with respect to the outer peripheral surface is set to a predetermined intersecting angle as described above. A portion that is thin (a sharp angle in a cross-sectional view) can be eliminated. As a result, molding defects such as chipping during demolding can be suppressed and yield can be improved. Further, even after mounting on the vehicle, it is possible to suppress damage such as chipping and improve durability.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. First, the structure of the suspension mechanism 100 in which the dust cover 1 is incorporated will be described with reference to FIG. FIG. 1 is a cross-sectional view of a suspension mechanism 100 incorporating a dust cover 1 according to the first embodiment of the present invention.

  As shown in FIG. 1, the suspension mechanism 100 supports a wheel (not shown) so as to be relatively movable with respect to a vehicle body (not shown), and absorbs an impact transmitted from the wheel, thereby driving the vehicle body. This is for ensuring stability and ride comfort of the occupant, and includes a strut mount 2, a piston rod 4, a cylinder 5, a bound stopper 6, and a dust cover 1.

  The strut mount 2 is a member for supporting the piston rod 4 and preventing transmission of vibrations transmitted through the piston rod 4 to a vehicle body (not shown), a plate 11 having a through hole, A cup fitting 12 mounted on the plate 11 (upper in FIG. 1) by spot welding and configured to project outward from one end side (lower side in FIG. 1) of the substantially cylindrical body (outward in the left-right direction in FIG. 1). And a holding metal fitting 13 configured in a substantially cylindrical shape, which is attached to the surface on the back side (lower side in FIG. 1) of the surface of the plate 11 to which the cup metal fitting 12 is attached, and vulcanized and bonded to the cup metal fitting 12. The flange bracket 14 is provided.

  The flange metal fitting 14 is a member for attaching the piston rod 4 to the strut mount 2, and includes a flange portion that has an axial center and is formed by projecting in a flange shape radially outward from the upper end of the substantially cylindrical shape. The rubber elastic member G is vulcanized and bonded to the flange portion and the inner peripheral surface of the cup fitting 12. Therefore, the flange metal member 14 is connected to the cup metal member 12 in an inclinable state by the deformation of the rubber elastic member G.

  The flange fitting 14 is inserted through the through hole of the plate 11, and the upper end portion of the dust cover 1 is sandwiched between the outer peripheral surface of the flange fitting 14 and the holding fitting 13.

  As shown in FIG. 1, the piston rod 4 has a shaft O and is formed in a substantially rod shape, and one end side (upper end side in FIG. 1) is fastened to the flange metal fitting 14, and below the plate 11 (lower side in FIG. 1). It is extended to.

  The cylinder 5 is connected to an arm (not shown) that supports a wheel (not shown) so as to be relatively movable with respect to a vehicle body (not shown), and interlocks with a relative movement between the wheel and the vehicle body (not shown). The member moves relative to the piston rod 4 and exhibits a damping function. The member has an axis O and is formed in a substantially cylindrical shape and is externally fitted to the piston rod 4.

  Further, the piston rod 4 and the cylinder 5 are arranged in a state of being inclined in a range of 0 degrees or more and 3 degrees or less with respect to the vertical direction (downward direction in FIG. 1).

  Further, since the arm (not shown) swings while being supported at one place, the portion where the cylinder 5 is attached moves circularly. Therefore, the part of the cylinder 5 opposite to the part where the piston rod 4 is fitted is circularly moved.

  The cylinder 5 is slidable in the direction of the axis O (vertical direction in FIG. 1) with respect to the piston rod 4, and is a portion of both ends of the piston rod 4 where the cylinder 5 is externally fitted. The opposite part is pivotally supported by a flange fitting 14 vulcanized and bonded to the rubber elastic member G.

  In this way, the parts at both ends of the cylinder 5 that are opposite to the parts into which the piston rod 4 is fitted circularly move, and the parts at both ends of the piston rod 4 that are fitted outside the cylinder 5 Is supported by a flange fitting 14 that is vulcanized and bonded to the rubber elastic member G. Therefore, when the arm (not shown) swings, the cylinder 5 moves relative to the piston rod 4. Meanwhile, the axis O of the cylinder 5 and the piston rod 4 changes the inclination with respect to the vehicle body (not shown).

  As shown in FIG. 1, the bound stopper 6 is a member that exerts a stopper function by being pressed by a cylinder 5 that moves toward the vehicle body side (upper side in FIG. 1). It is configured in a shape and is fitted in the dust cover 1. The dimension value of the bound stopper 6 in the direction of the axis O (vertical direction in FIG. 1) is the height H8.

  The dust cover 1 is a member mainly for protecting the piston rod 4 from dust such as sand and stones scattered from the road surface. The dust cover 1 has an axis O and is viewed from the rubber-like elastic body in the direction of the axis O (see FIG. 1 Viewed in the vertical direction) It is configured in a substantially cylindrical shape, and includes an inner fitting portion 21, a stopper holding portion 22, a bellows portion 23, and a cylindrical portion 24.

  As shown in FIG. 1, the inner fitting portion 21 is a portion that is fixed to the strut mount 2 side by the holding bracket 13, has an axis O, and is substantially annular as viewed in the direction of the axis O (viewed in the vertical direction in FIG. 1). And is fitted in the holding metal fitting 13.

  The stopper holding part 22 is a part for holding the bound stopper 6, and is formed in a substantially cylindrical shape from the outer edge of the lower end side (lower side in FIG. 1) of the inner fitting part 21 toward the wheel side (lower side in FIG. 1). The dimension value in the axial center O direction (vertical direction in FIG. 1) is set to a height H6.

  Here, the height H6 of the stopper holding portion 22 is preferably set in a range of 0.3 to 0.5 times the height H8 of the bound stopper 6 (0.3 × H8 <H6 <0. 5 × H8). In this case, since the fitting allowance of the bound stopper 6 and the stopper holding part 22 can be ensured, the stopper holding part 22 can hold the bound stopper 6 reliably.

  As shown in FIG. 1, the bellows portion 23 is a portion that absorbs deformation of the dust cover 1 by deformation of the bellows portion 23 itself, and has a substantially cylindrical shape and a side surface that is bent into a bellows shape. The stopper holding portion 22 extends from the inner edge of the lower end side (lower side in FIG. 1) toward the wheel side (lower side in FIG. 1). The dimension value of the bellows portion 23 in the axis O direction (vertical direction in FIG. 1) is the height H1.

  Here, the height H1 of the bellows portion 23 is set so that the sum of the height H6 of the stopper holding portion 22 is in the range of 0.8 times to 1.1 times the height H8 of the bound stopper 6. It is preferable (0.8 × H8 <H6 + H1 <1.1 × H8).

  In this case, the bellows portion 23 does not contact the bound stopper 5 but contacts only the bound stopper 6, so that the problem of peeling off of the cylinder 5 by the bellows portion 23 does not occur. In addition, since the bound stopper 6 is an unpainted member, the problem of paint peeling does not occur even if the bellows portion 23 is brought into contact.

  Therefore, when force is applied to the bellows portion 23 from the direction perpendicular to the axis O direction (left and right direction in FIG. 1) (when the dust cover 1 swings in the left and right direction due to vibration while the vehicle is traveling), the bound stopper 6 There is no problem even if it touches. Therefore, the lateral rigidity of the bellows part 23 (the rigidity in the direction orthogonal to the direction of the axis O) can be made lower than the lateral rigidity of the cylindrical part 24. As a result, the bellows portion 23 is deformed before the cylindrical portion 24 and the deformation amount of the cylindrical portion 24 can be reduced.

  The interval between the substantially cylindrical inner surface and the outer surface of the bellows portion 23 is a thickness T8, which is approximately the same size as a thickness T3 of a cylindrical portion 24 described later. Therefore, since the bellows portion 23 is formed in a bellows shape with respect to the cylindrical portion 24, rigidity can be kept low with respect to the cylindrical portion 24.

  As shown in FIG. 1, the cylindrical portion 24 is a portion for protecting the piston rod 4 from dust such as sand and stones scattered from the road surface, and has an axial center O and is configured in a substantially cylindrical shape. The bellows portion 23 extends from the lower end side (lower side in FIG. 1) toward the wheel side (lower side in FIG. 1). The dimension value of the cylindrical portion 24 in the direction of the axis O (vertical direction in FIG. 1) is the height H2, and the axis between the inner peripheral surface 24a that is the cylindrical inner surface and the outer peripheral surface 24c that is the outer surface. The interval in the direction orthogonal to the center O direction (left and right direction in FIG. 1) is the thickness T3.

  Further, as shown in FIG. 1, the cylindrical portion 24 is a portion that houses the piston rod 4, a part of the cylinder 5, and the bound stopper 6, and a plurality (eight in this embodiment) of linear rib portions 25. And a plurality (three in the present embodiment) of annular rib portions 26 and lip portions 27 are provided.

  As shown in FIG. 1, the linear rib portion 25 is a portion for suppressing deformation of the cylindrical portion 24, and is projected on the outer peripheral surface 24 c of the cylindrical portion 24 at an interval of approximately 45 degrees (FIG. 5 ( a)), extending from the upper end (upper end of FIG. 1) to the lower end (lower end of FIG. 1) of the cylindrical portion 24 along the axis O of the cylindrical portion 24.

  That is, the dimension value of the linear rib portion 25 in the axial center O direction (the vertical direction in FIG. 1) is the height H2. Therefore, the lateral rigidity (stiffness in the direction orthogonal to the axis O direction) of the cylindrical portion 24 can be made uniform along the axis O direction. Therefore, the shape of the cylindrical portion 24 is easily maintained.

  Here, when the lateral stiffness of the bellows portion 23 (the stiffness in the direction orthogonal to the axial center O direction) is set to be smaller than the lateral stiffness of the cylindrical portion 24, as described above, it is orthogonal to the axial center O direction. When force is applied to the cylindrical portion 24 from the direction (left and right direction in FIG. 1), the bellows portion 23 is deformed before the cylindrical portion 24 is deformed, and the deformation amount of the cylindrical portion 24 can be reduced.

  Therefore, when a force acts on the cylindrical portion 24 from a direction orthogonal to the direction of the axis O (the left-right direction in FIG. 1) (when the dust cover 1 swings in the left-right direction due to vibration during traveling of the vehicle), the cylindrical portion 24. Is moved in the direction orthogonal to the direction of the axis O (the left-right direction in FIG. 1) by the amount of deformation of the bellows portion 23 while maintaining the shape.

  That is, since the shape of the cylindrical portion 24 is maintained, the deviation between the portion where the cylinder 5 and the cylindrical portion 24 actually contact and the contact portion assumed from the shape of the cylinder 5 and the cylindrical portion 24 is reduced. The contact portion between the cylinder 5 and the cylindrical portion 24 can be examined on the drawings of the cylinder 5 and the cylindrical portion 24.

  As shown in FIG. 1, the annular rib portion 26 is outward (from the left-right direction in FIG. 1) on the outer peripheral surface 24 c that is the outer peripheral surface of the cylindrical portion 24 and intersects with a virtual plane orthogonal to the straight rib portion 25. While projecting outwardly, the outer peripheral surface 24c is continuously extended over the entire circumference, and the dimension value in the axial center O direction (vertical direction in FIG. 1) is the width H3, orthogonal to the axial center O direction. The dimension value in the direction (the left-right direction in FIG. 1) is the height T6. Further, a plurality (three in the present embodiment) of the annular rib portions 26 are disposed at a distance H4 along the axial center O direction (vertical direction in FIG. 1).

  Here, the width H3 of the annular rib portion 26 is preferably set in a range of 2.0 to 3.0 times the height T6 of the annular rib portion 26 (2.0 × T6 <H3 <3. 0xT6). In this case, the rigidity of the cylindrical portion 24 can be improved efficiently by forming the annular rib portion 26 in the cylindrical portion 24.

  For example, when the width H3 is set to be 2.0 times or less of the height T6, the ratio that contributes to the rigidity of the cylindrical portion 24 becomes smaller toward the tip side of the annular rib portion 26, resulting in poor efficiency. A point arises.

  Further, when the width H3 is set to 3.0 times or more of the height T6, the ratio of the annular rib portion 26 contributing to the rigidity of the cylindrical portion 24 is increased, but the increase in the rubber-like elastic body to be used is remarkably increased. A problem arises in that the weight of the annular rib portion 26 increases and the weight of the dust cover 1 increases.

  On the other hand, in the annular rib portion 26 in the present embodiment, the width H3 of the annular rib portion 26 is set in the range of 2.0 times to 3.0 times the height T6 of the annular rib portion 26. This problem can be solved.

  Here, the width H3 of the annular rib portion 26 is preferably set in a range of 0.1 to 0.2 times the distance H4 (0.1 × H4 <H3 <0.2 × H4). H1 of the accordion portion 23 is preferably set in a range of 0.8 to 1.2 times the distance H4 (0.8 × H4 <H1 <1.2 × H4). The thickness T3 of the portion 24 is preferably set in the range of 0.9 to 1.1 times the thickness T8 of the bellows portion 23 (0.9 × T8 <T3 <1.1 × T8).

  In this case, since the lateral rigidity (right and left direction in FIG. 1) of the cylindrical portion 24 can be higher than the lateral rigidity of the bellows portion 23, a force is applied to the cylindrical portion 24 from a direction orthogonal to the axis O direction (left and right direction in FIG. 1). When acted (when the dust cover 1 swings in the left-right direction due to vibration while the vehicle is running), the bellows portion 23 is in a direction perpendicular to the direction of the axis O before the cylindrical portion 24 (left-right direction in FIG. 1). Since deformation occurs, deformation in the direction perpendicular to the direction of the axis O of the cylindrical portion 24 can be reduced.

  Further, the annular rib portion 26 disposed at the lowest end of the cylindrical portion 24 (the lowest end in the vertical direction in FIG. 1) has a distance H5 from the adjacent annular rib portion 26 along the axis O direction (the vertical direction in FIG. 1). They are spaced apart.

  Here, the distance H5 is preferably set in a range of 0.3 to 0.4 times the distance H4 (0.3 × H4 <H5 <0.4 × H4). That is, the distance H5, which is the length of the portion of the cylindrical portion 24 formed below the lowermost annular rib portion 26, is disposed between each of a plurality (four in the present embodiment) of the annular rib portions 26. By forming the portion shorter than the distance H4 which is the length of the portion to be formed, the rigidity of the portion of the cylindrical portion 24 formed below the lowermost annular rib portion 26 is plural (four in the present embodiment). By making it equal to the rigidity of the part arrange | positioned between each annular rib part 26, the rigidity of the cylindrical part 24 whole can be kept uniform.

  The lip portion 27 protrudes inward (inward in the left-right direction in FIG. 1) from the surface on the inner peripheral surface 24a that is the inner peripheral surface of the cylindrical portion 24 and intersects with a virtual plane orthogonal to the linear rib portion 25. On the other hand, it extends continuously over the inner peripheral surface 24a.

  Thus, since the lip portion 27 is projected inward (inward in the left-right direction in FIG. 1) from the inner peripheral surface 24 a of the cylindrical portion 24, the lip portion 27 is brought into contact with the outer peripheral surface of the cylinder 5. The area where the inner peripheral surface 24 a contacts the outer peripheral surface of the cylinder 5 can be reduced to prevent the inner peripheral surface 24 a from sticking to the outer peripheral surface of the cylinder 5.

  When this sticking occurs, the outer peripheral surface of the cylinder 5 is rubbed by the inner peripheral surface 24a of the dust cover 1 as the piston rod 4 and the cylinder 5 are moving (stretching and contracting), and the paint is peeled off. appear.

  Here, a configuration in which the lip portion 27 is omitted will be described. For example, when water enters between the outer peripheral surface of the cylinder 5 and the inner peripheral surface 24a of the cylindrical portion 24 due to rain, or when oil leaks from the inside of the cylinder 5 and the inner surface of the cylindrical portion 24 When oil enters between the peripheral surface 24 a and the inner peripheral surface 24 a of the cylindrical portion 24 may stick to the outer peripheral surface of the cylinder 5 with water or oil.

  When the inner peripheral surface 24a of the cylindrical portion 24 sticks to the outer peripheral surface of the cylinder 5 due to water or oil, the cylinder 5 moves relative to the piston rod 4 and the dust cover 1 moves in the vertical direction (the vertical direction in FIG. 1). When the dust cover 1 is moved, the dust cover 1 is pulled or compressed, and the inner peripheral surface 24a and the outer peripheral surface 24c of the cylindrical portion 24 are distorted to generate cracks, or the cracks are enlarged and the dust cover 1 is broken. There is a fear.

  Further, since the dust cover 1 is held in a bent state with the deformation of the dust cover 1 and the initial shape cannot be maintained, the exposure of the piston rod 4 increases, leading to a problem that the protection function is lowered.

  If the cylindrical portion 24 is formed in a bellows shape in which peaks and valleys are alternately arranged, the contact area with the cylinder 5 can be reduced and sticking to the outer peripheral surface of the cylinder 5 can be suppressed.

  However, the cylindrical portion 24 is configured in a cylindrical shape to improve the rigidity and maintain the shape, thereby improving the protective effect of the cylinder 5, while in contact with the outer peripheral surface of the cylinder 5, Compared to the bellows shape, the contact area is large and the cylinder 5 is easily stuck to the outer peripheral surface.

  On the other hand, in the dust cover 1 according to the present embodiment, the lip portion 27 is formed so as to protrude inward (inward in the left-right direction in FIG. 1) from the inner peripheral surface 24a of the cylindrical portion 24. The point can be solved. As a result, it is possible to prevent cracks in the dust cover 1, breakage, and deterioration of the protective function.

  Further, the dust cover 1 has an upper end (upper end in FIG. 1) solidified by the holding metal 13, and a lower end (lower end in FIG. 1) swings back and forth and left and right due to vibration during traveling of the vehicle (not shown). The lower end of 1 is the position where it is most likely to contact the cylinder 5.

  Therefore, since the lip portion 27 is formed at the lower end (lower end in FIG. 1) of the cylindrical portion 24, it is possible to efficiently prevent the inner peripheral surface 24a of the cylindrical portion 24 from sticking to the outer peripheral surface of the Linder 5.

  Further, when the lip portion 27 is continuously projected in the circumferential direction of the cylindrical portion 24, the dust cover 1 swings in any of the front, rear, left and right directions due to vibration during traveling of the vehicle (not shown). However, the lip portion 27 can be reliably brought into contact with the outer peripheral surface of the cylinder 5. Therefore, the inner peripheral surface 24 a of the cylindrical portion 24 can be reliably suppressed from sticking to the outer peripheral surface of the cylinder 5.

  Furthermore, as described above, the lip 27 is intermittently disposed in the circumferential direction of the cylindrical portion 24 by projecting the lip portion 27 continuously in the circumferential direction of the cylindrical portion 24. Compared to the configuration, the strength of the lip portion 27 can be ensured, and damage to the lip portion 27 due to contact with the outer peripheral surface of the cylinder 5 can be suppressed. As a result, the durability of the dust cover 1 can be improved and the function of suppressing sticking can be maintained.

  Further, as described above, the lip portion 27 is continuously provided in the circumferential direction of the cylindrical portion 24 so that the lip portion 27 is intermittently disposed in the circumferential direction of the cylindrical portion 24. As a result, it is possible to ensure the demoldability from the vulcanizing mold 90 (see FIG. 6), so that the chipping of the lip portion 27 at the time of demolding is suppressed and the yield in the manufacturing process of the dust cover 1 is reduced. Improvements can be made.

  Next, the detailed structure of the lip portion 27 will be described with reference to FIGS. 2 is a partially enlarged cross-sectional view of the lip portion 27 shown by enlarging the portion A in FIG. 1, and FIG. 3 is a portion of the second arc portion 27b shown by enlarging the portion B in FIG. FIG. 4 is an enlarged cross-sectional view, and FIG. 4 is a partial enlarged cross-sectional view of the second arc portion 27b showing a state in which the cylinder 5 is in contact with the end portion P2 of the lip portion 27.

  In FIG. 2, the outer peripheral surface of the cylinder 5 inclined by the expansion and contraction of the cylinder 5 with respect to the piston rod 4 is indicated by a two-dot chain line. Further, in order to facilitate understanding of the shape of the lip portion 27, the extension lines along the arc shapes of the first arc portion 27a and the second arc portion 27b are illustrated using thin lines.

  FIG. 3 shows the outer peripheral surface of the cylinder 5 with the tilt angle changed (three patterns) by a two-dot chain line. 4 shows a state in which the lip portion 27 is deformed by the cylinder 5 being abutted against the lip portion 27, and also shows a state before being deformed by a two-dot chain line. Corresponding to

  As shown in FIG. 2, the outer peripheral surface of the lip portion 27 is connected to an inner peripheral surface 24a, which is an inner surface of the cylindrical portion 24, and is formed outwardly (leftward in FIG. 2) into a concave cross-sectional arc shape. The first circular arc portion 27a, the tapered linear portion 27c that is connected to the lower end surface 24b of the cylindrical portion 24 and formed linearly, and is disposed between the tapered linear portion 27c and the first circular arc portion 27a. And a second arc portion 27b formed in an inwardly convex cross-sectional arc shape.

  Further, the curvature of the first arc portion 27a is set to the curvature r1, and the curvature of the second arc portion 27b is set to the curvature r2 that is larger than the curvature r1 (r2> r1). When the curvature r1 and the curvature r2 are set in this way, the tension applied to the lip portion 27 at the time of mold release in the manufacturing process is distributed in a balanced manner.

  Therefore, since the distortion of the outer peripheral surface of the lip portion 27 can be dispersed throughout, the occurrence of cracks on the outer peripheral surface of the lip portion 27 can be suppressed. Details will be described later with reference to FIG.

  In the taper straight portion 27c, the inclination angle with respect to the axis O direction (vertical direction in FIG. 2) is an angle θ1, and the inclination angle of the lower end surface 24b with respect to the outer peripheral surface 24c is an angle θ3. The angle θ1 is preferably set in the range of 30 degrees to 60 degrees. In that case, the inclination angle θ4 formed by the lower end surface 24b and the taper straight portion 27c in the cross section including the axis O in the connection portion P1 is 120 ° to 150 °. The angle θ3 is preferably set in the range of 90 degrees to 150 degrees.

  The taper straight portion 27c has a planar cross-sectional shape configured in a substantially annular shape, and has an inner diameter on the upper end (upper end in FIG. 2) side of the taper straight portion 27c. Corresponds to the inner diameter on the lower end (lower end in FIG. 2) side of the outer peripheral surface 24c (corresponding to “the inner diameter at the end of the tapered surface” according to claim 2). is doing.

  Therefore, when a force is applied from a direction orthogonal to the direction of the axis O (left and right direction in FIG. 2) (when the dust cover 1 swings in the left and right direction due to vibration during traveling of the vehicle), the taper straight portion 27c is connected to the cylinder 5. It can suppress contacting with the outer peripheral surface of. As a result, paint peeling of the cylinder 5 can be suppressed.

  As shown in FIG. 2, the inner peripheral surface 24a is formed in a linear cross section and is formed at a position away from the outer peripheral surface 24c in the radial direction of the cylindrical portion 24 (right direction in FIG. 2) by a thickness T3. The lower end surface 24b is connected to the outer peripheral surface 24c, which is the outer surface of the cylindrical portion 24, and the tapered straight portion 27c. The dimension of the cylindrical portion 24 in the radial direction (left-right direction in FIG. 2) is the thickness T1. Is set to

  That is, the connecting portion P1 between the lower end surface 24b and the taper straight portion 27c is located on the outer peripheral surface 24c side (left side in FIG. 2) in the radial direction (left and right direction in FIG. 2) of the cylindrical portion 24 from the extension line of the inner peripheral surface 24a. Yes. The thickness T1 is preferably set in the range of 0.5 to 0.8 times the thickness T3 (0.5 × T3 <T1 <0.8 × T3).

  For example, when the lip portion 27 is omitted and the inner peripheral surface 24a and the lower end surface 24b are directly connected, the inner peripheral surface 24a and the cylindrical portion are provided at the lower end (lower end in FIG. 2) of the inner peripheral surface 24a. A connecting portion with 24b is formed. Therefore, when the cylinder 5 and the cylindrical portion 24 are relatively inclined, the connecting portion first comes into contact with the outer peripheral surface of the cylinder 5, which causes a problem that the cylinder 5 is peeled off.

  On the other hand, in the present embodiment, the connecting portion P1 between the lower end surface 24b and the taper straight portion 27c is positioned on the outer peripheral surface 24c side in the radial direction of the cylindrical portion 24 (the left direction in FIG. 2) from the extension line of the inner peripheral surface 24a. Since it is located in the left side of FIG. 2, it can be made easy to avoid that the cylinder 5 contacts the connection part P1. As a result, the paint peeling of the cylinder 5 can be made difficult to occur.

  Further, when the lip portion 27 is omitted and the inner peripheral surface 24a and the lower end surface 24b are directly connected, a connecting portion between the inner peripheral surface 24a and the cylindrical portion 24b at the lower end of the inner peripheral surface 24a. Are formed in a right-angled shape.

  Therefore, when the cylinder 5 and the cylindrical part 24 are relatively inclined and the cylinder 5 and the connecting part come into contact with each other, the painted surface of the cylinder 5 and the right-angled corner come into contact with each other. The maximum value of the pressure applied to the cylinder 5 is increased, and there arises a problem that paint peeling of the cylinder 5 is promoted.

  Here, in the present embodiment, the angle formed between the lower end surface 24b and the tapered straight portion 27c in the cross section including the axis O in the connection portion P1 is 120 degrees to 150 degrees, so that the right angle (90 degrees) Compared with the case where it is done, the maximum value of the pressure applied to the painted surface of the cylinder 5 can be suppressed. As a result, paint peeling of the cylinder 5 can be suppressed.

  Further, since the taper straight part 27c is formed in a straight line shape, when the taper straight part 27c is provided on the outer peripheral surface of the cylinder 5, the entire straight line comes into contact with each other, so that the maximum value of the contact pressure is reduced. The paint peeling of 5 can be suppressed.

  Further, in the case where the cross-sectional shape of the lip portion 27 is rectangular, when the outer peripheral surface of the cylinder 5 is abutted against a rectangular flat surface, the contact area between the lip portion 27 and the outer peripheral surface of the cylinder 5 is increased. When the outer peripheral surface of the cylinder 5 hits a rectangular corner, the contact area becomes small and sticking is difficult to occur. The pressure on the surface in contact with the cylinder 5 becomes high, causing a problem that paint peeling of the cylinder 5 occurs.

  On the other hand, in the present embodiment, the second arc portion 27b is formed in an inwardly convex cross-sectional arc shape (right direction in FIG. 2), and the curvature of the arc is set to the curvature r1. Therefore, as shown in FIG. 4, when the cylinder 5 comes into contact with the lip portion 27 and the lip portion 27 is deformed by a distance T9 in the radial direction (left and right direction in FIG. 4) of the cylindrical portion 24, the axial center of the cylindrical portion 24 is obtained. The dimension of the contact portion in the O (see FIG. 1) direction (vertical direction in FIG. 4) can be expanded to a length H9.

  In addition, when the force which presses the 2nd circular arc part 27b to the cylinder 5 is constant, length H9 is a value which increases or decreases according to the magnitude | size of the value of curvature r1, and it is so large that the value of curvature r1 is large. The value of the length H9 also increases (L1∝r1).

  Therefore, it is possible to secure a wide contact area between the end portion P2 of the second arc portion 27b and the cylinder 5 and reduce the maximum value of the pressure applied to the contact surface between the cylinder 5 and the second arc portion 27b. it can.

  As a result, the pressure applied to the painted surface of the cylinder 5 can be reduced to prevent the paint peeling of the cylinder 5 and the size of the contact area between the lip portion 27 and the outer peripheral surface of the cylinder 5 can be set appropriately. The sticking between the lip portion 27 and the cylinder 5 is reduced.

  Further, as shown in FIG. 2, the distance in the radial direction (left and right direction in FIG. 2) of the cylindrical portion 24 between the distal end portion P2 and the connecting portion P1 that protrudes inwardly (right side in FIG. 2) of the second arc portion 27b. The distance T2 is set so that the sum of the thickness T1 and the distance T2 is larger than the thickness T3. That is, the second arc portion 27b protrudes from the inner peripheral surface 24a inward in the radial direction of the cylindrical portion 24 (right side in FIG. 2).

  Also, since the second arc portion 27b is formed in an inwardly convex cross-sectional arc shape (rightward in FIG. 2), the relative angle between the cylinder 5 and the lip portion 27 changes as shown in FIG. However, the cylinder 5 contacts the arc of the second arc portion 27b.

  Therefore, even when the relative angle between the cylinder 5 and the lip portion 27 changes, it is possible to secure a wide contact area between the end portion P2 of the second arc portion 27b and the cylinder 5 and reduce the maximum value of the contact pressure. it can. As a result, the pressure applied to the painted surface of the cylinder 5 can be reduced, and the paint peeling of the cylinder 5 can be prevented.

  As described above, since the connecting portion P1 is located closer to the outer peripheral surface 24c than the inner peripheral surface 24a, the thickness of the lower end of the cylindrical portion 24 becomes thin, and it is difficult to ensure a predetermined strength. Therefore, when the dust cover 1 swings back and forth and left and right due to vibration during traveling of the vehicle (not shown), a part thereof is chipped or cracked, resulting in a decrease in durability. Similarly, even when the mold is removed from the vulcanization mold 90 (see FIG. 6), chipping and cracking occur due to the decrease in strength, leading to a decrease in yield in the manufacturing process of the dust cover 1.

  On the other hand, in the present embodiment, since the second arc portion 27b protrudes inward (right side in FIG. 2) from the inner peripheral surface 24a of the cylindrical portion 24, the thickness of the lower end of the cylindrical portion 24 is reduced. Can compensate for the wall thickness. Accordingly, the strength of the cylindrical portion 24 can be ensured and the occurrence of chipping and cracking can be suppressed. As a result, it is possible to improve the durability of the dust cover 1 and improve the yield.

  When the lower end surface 24b is omitted and the outer peripheral surface 24c and the tapered straight portion 27c are directly connected, the crossing angle between the tapered straight portion 27c and the outer peripheral surface 24c is an acute angle (from 90 degrees). Small angle), and the connecting portion is thin.

  On the other hand, even if the lower end surface 24b is provided between the outer peripheral surface 24c of the cylindrical portion 24 and the tapered straight portion 27c, the intersection angle between the lower end surface 24b and the outer peripheral surface 24c extends the tapered straight portion 27c. Similarly, if the angle is smaller than the intersection angle between the imaginary line and the outer peripheral surface 24c, the outer peripheral surface 24c, the lower end surface 24b, and the connecting portion are thin.

  Therefore, at the time of demolding from the vulcanizing mold 90 (see FIG. 6), molding defects such as chipping are likely to occur in the connecting portion that is thin, and the yield is reduced in the manufacturing process of the dust cover 1. Further, even if there is no molding failure such as chipping when demolding from the vulcanizing mold 90, if there is a portion that is thin (acute angle in cross-sectional view), it should be mounted after mounting on a vehicle (not shown). Accompanied by this, damage such as chipping is likely to occur, and a defect that the crack starts from the damaged part is caused.

  In contrast, in the present embodiment, a lower end surface 24b is provided between the outer peripheral surface 24c and the taper straight portion 27c, and the angle of intersection of the taper straight portion 27c with respect to the outer peripheral surface 24c is set to an angle θ3 and a lower angle with respect to the outer peripheral surface 24c. By setting the crossing angle of the end face 24b to the angle θ1, it is possible to eliminate the part that becomes thin by eliminating the part that becomes an acute angle.

  As a result, molding defects such as chipping at the time of demolding can be suppressed, and the yield can be improved in the manufacturing process of the dust cover 1. In addition, even after mounting on a vehicle (not shown), damage such as chipping can be suppressed, and the durability of the dust cover 1 can be improved.

  As shown in FIG. 2, the inner peripheral surface 24a is in contact with the first arc portion 27a, the first arc portion 27a is in contact with the second arc portion 27b, and the second arc portion 27b is tapered linearly. The part 27c is in contact.

  That is, the connected part from the inner peripheral surface 24a to the taper linear part 27c is smoothly connected. Therefore, it is possible to prevent the lip portion 27 from being caught on the vulcanization mold 90 (see FIG. 6) at the time of mold release in the manufacturing process.

  Therefore, since the distortion of the outer peripheral surface of the lip portion 27 (the first arc portion 27a, the second arc portion 27b, and the tapered straight portion 27c) can be dispersed throughout, the outer peripheral surface of the lip portion 27 is cracked. Can be suppressed. Details will be described later with reference to FIG.

  Further, it is preferable that the curvature r1 of the first arc portion 27a is set to be approximately three times or more the curvature r2 of the second arc portion 27b (r2 ≧ 3 × r1).

  For example, if the curvature r1 of the first arc portion 27a is made too small with respect to about three times the curvature r2 of the second arc portion 27b (for example, equivalent to the curvature r2 of the second arc portion 27b), the first arc is released at the time of mold release. The arc portion 27a is easily caught on the vulcanization mold 90 (see FIG. 6), and the cylindrical portion 24 is pulled in the direction in which the vulcanization mold 90 is extracted (downward direction in FIG. 7). This is because the distortion of 24a and the outer peripheral surface 24c increases.

  That is, when the curvature r1 of the first arc portion 27a is set to a dimension value smaller than about three times the curvature r2 of the second arc portion 27b, a large force is applied to the cylindrical portion 24 and the inner peripheral surface 24a of the cylindrical portion 24 is applied. And the distortion which outer peripheral surface 24c produces will increase.

  The ratio of the curvature r1 of the first arc portion 27a and the curvature r2 of the second arc portion 27b is more preferably set such that the ratio r1: r2 is in the range of 4.5: 1 to 3.5: 1. Most preferably, the ratio r2: r1 is set to a value in the vicinity of 4: 1.

  As described above, when the ratio r2: r1 is set to a value in the vicinity of 4: 1, when the lip portion 27 is deformed, the distortion of the outer peripheral surface (the first arc portion 27a and the second arc portion 27b) is made uniform throughout. This is because it can be dispersed.

  Further, the end P2 of the second arc portion 27b has a distance T4 in a direction perpendicular to the axis O (see FIG. 1) from the inner peripheral surface 24a and inward of the inner peripheral surface 24a (right direction in FIG. 2). The first arc portion 27a is disposed at a position that is perpendicular to the axis O (see FIG. 1) from the inner peripheral surface 24a and inward of the inner peripheral surface 24a (right direction in FIG. 2). The inclination angle with respect to the axis O of the part separated by the distance T5 is set to the angle θ2.

  The distance T5 is preferably set to 1/4 of the distance T4, and the angle θ2 is preferably set in the range of 25 degrees to 35 degrees. Therefore, when the dust cover 1 is released from the vulcanization mold 90 (see FIG. 6), it is possible to avoid applying an excessive force to the dust cover 1. Details will be described later with reference to FIG.

  In addition, the taper straight portion 27c is set to an angle θ1 with respect to the direction of the axis O (see FIG. 1) (vertical direction in FIG. 2), and the angle θ1 is set in the range of 30 degrees to 60 degrees. Is preferred. In this case, when the dust cover 1 is released from the vulcanization mold 90 (see FIG. 6), it is possible to avoid applying an excessive force to the dust cover 1. Details will be described later with reference to FIG.

  Next, the straight rib portion 25 and the annular rib portion 26 formed on the outer peripheral surface of the cylindrical portion 24 will be described with reference to FIG. 5A is a cross-sectional view of the dust cover 1 taken along the line Va-Va of FIG. 1, and FIG. 5B is an annular rib at a position on the back surface of the lip portion 27 on the outer peripheral surface of the dust cover 1. It is sectional drawing of the dust cover 1 in case the part 26 is formed, and respond | corresponds to Fig.5 (a).

  In FIG. 5A, the state where the dust cover 1 is in contact with the cylinder 5 and deformed to the maximum is indicated by a solid line, and the state before being deformed is indicated by a two-dot chain line. Similarly, in FIG. 5B, the state where the dust cover 1 is in contact with the cylinder 5 and deformed to the maximum is indicated by a solid line, and the state before being deformed is indicated by a two-dot chain line.

  As shown in FIG. 5A, the annular rib portion 26 is not provided on the outer peripheral surface 24 c of the cylindrical portion 24 and on the back side of the lip portion 27, and the linear rib portion 25 is replaced with the cylindrical portion 24. Are disposed at equal intervals in the circumferential direction at an angle θ5.

  That is, the rigidity of the lip portion 27 in the radial direction (the direction toward the axis O shown in FIG. 5A) is set to be low as the annular rib portion 26 is omitted. Therefore, when the lip portion 27 comes into contact with the outer peripheral surface of the cylinder 5, the shape of the lip portion 27 is easily deformed following the outer shape of the cylinder 5.

  Therefore, when the lip portion comes into contact with the shock absorber, it is easily deformed in the radial direction of the lip portion 27 (the direction toward the axis O shown in FIG. 5A). Therefore, since the lip portion 27 is deformed following the outer periphery of the cylinder 5, a wide contact area between the second arc portion 27b of the lip portion 27 and the outer peripheral surface of the cylinder 5 is secured, and the maximum value of the contact pressure is reduced. can do.

  As a result, the maximum value of the pressure applied to the painted surface of the cylinder 5 can be reduced, and the peeling of the cylinder 5 can be suppressed.

  In this case, the straight rib portion 25 is formed at a portion on the back side of the lip portion 27, and the straight rib portion 25 extends over the entire range in the axial direction of the cylindrical portion 24 (the vertical direction in FIG. 5A). Therefore, the cylindrical portion 24 can be prevented from being bent with respect to the axis O.

  Therefore, the shape change of the cylindrical part 24 in the direction perpendicular to the axis O can be suppressed, and the paint peeling of the cylinder 5 can be suppressed while maintaining the protection function of the piston rod 4.

  Next, with reference to FIG.6 and FIG.7, the structure of the vulcanization mold 90 which shape | molds the dust cover 1 is demonstrated. FIG. 6 is a cross-sectional view of the first mold 91, the second mold 92, and the third mold 93 in a closed state. FIG. 7 is a cross-sectional view of the first mold 91, the second mold 92, and the third mold 93 in a state where the mold is divided.

  As shown in FIGS. 6 and 7, a first die 91 that mainly molds the inner peripheral shape of the dust cover 1, and a rubber-like member inside the vulcanizing mold 90 that mainly molds the outer peripheral shape of the dust cover 1. A vulcanizing mold 90 for molding the dust cover 1 is composed of a second mold 92 having an injection hole 94 for injecting an elastic body and a third mold 93 for mainly molding the outer peripheral shape of the dust cover 1. The second mold 92 and the third mold 93 are moved with respect to the first mold 91 and divided by the mold closing mold.

  As shown in FIG. 7, the mold closing mold splitting direction is a direction perpendicular to the axial direction (vertical direction in FIG. 6) of the dust cover 1 to be molded (horizontal direction in FIG. 6). The third mold 93 is moved in the opposite direction.

  Next, the process of releasing the lip portion 27 of the dust cover 1 will be described with reference to FIG. FIG. 8 is a state transition diagram showing a state where the lip portion 27 of the dust cover 1 is released. The second mold 92 and the third mold 93 have the same configuration as the third mold 93 except that the second mold 92 has an injection hole 94 for injecting a rubber-like elastic body. Therefore, the second mold 92 will be described, and the description of the third mold 93 will be omitted.

  FIG. 8A is a state transition diagram showing a state where the vulcanization mold 90 for molding the dust cover 1 is clamped, and FIG. 8B is a second mold of the vulcanization mold 90. FIG. 8C is a state transition diagram showing a state where the mold 92 and the third mold 93 are opened with respect to the first mold 91, and FIG. 8C is a state where the dust cover 1 is about to be extracted from the first mold 91. FIG. 8D is a state transition diagram illustrating a state in which the lip portion 27 of the dust cover 1 is removed from the first mold 91. In addition, the arrow shown in FIG.8 (c) and FIG.8 (d) has shown the flow of the air pumped.

  As shown in FIG. 8A, the outer peripheral surface 24 c of the dust cover 1 is formed by the molding surface 92 a of the second mold 92, and the lower end surface 24 b of the dust cover 1 is the molding surface of the first mold 91. The lip portion 27 of the dust cover 1 is molded with a molding surface 91b.

  As shown in FIG. 8 (b), the second mold 92 is divided from the state of FIG. 8 (a) and moved in a direction away from the first mold 91 (left direction in FIG. 8 (b)). The molding surface 92a is released from the surface 24c. In this case, the outer peripheral surface 24c may stick to the molding surface 92a.

  In particular, at the lower end of the cylindrical portion 24 (lower end in FIG. 8B), the force tends to concentrate, and when the force is applied by sticking to the molding surface 92a at the time of releasing, it tends to break or chip, resulting in a molding failure. It is a part. In addition, when a molding defect occurs, there is a problem that the yield deteriorates in the manufacturing process of the dust cover 1.

  As described above, in the present embodiment, the lower end surface 24b is provided between the outer peripheral surface 24c and the tapered linear portion 27c, and the angle of intersection of the tapered linear portion 27c with the outer peripheral surface 24c is set to the angle θ3 and the outer peripheral surface 24c. By setting the crossing angle of the lower end surface 24b to the angle θ1, a portion that becomes thin by eliminating an acute portion is eliminated. Therefore, even when stuck to the molding surface 92 a of the second mold 92, molding defects such as chipping at the time of demolding can be suppressed, and the yield can be improved in the manufacturing process of the dust cover 1.

  As shown in FIG. 8 (c), the mold splitting of the vulcanizing mold 90 is completed from the state of FIG. 8 (b), and the dust cover 1 is released from the first mold 91. When releasing the dust cover 1 from the first mold 91, the dust cover 1 is pulled out from the first mold 91 while air is pumped between the dust cover 1 and the first mold 91 to increase the inner diameter of the dust cover 1. In this case, at the time of diameter expansion, first, the cylindrical portion 24 is released from the molding surface 91a of the first mold 91, and the lip portion 27 is released from the molding surfaces 91a and 91b while being pulled by the cylindrical portion 24. .

  That is, the first arc portion 27a and the second arc portion 27b are pulled by the inner peripheral surface 24a, and the first arc portion 27a and the second arc portion 27b are located above the molding surface 91b (FIG. 8 (c) above). The mold is released while shifting to). Accordingly, a tensile force acts on the first arc portion 27a and the second arc portion 27b.

  Here, for example, when a portion having a large change in shape is formed in the connecting portion between the first arc portion 27a and the second arc portion 27b and the connecting portion between the first arc portion 27a and the inner peripheral surface 24a. In some cases, the force concentrates on the part where the shape has changed, and the lip portion 27 cracks and breaks.

  Here, in this Embodiment, it has comprised in the shape which connected smoothly the site | part connected from the internal peripheral surface 24a to the taper linear part 27c. Therefore, it is possible to prevent the lip portion 27 from being cracked and broken by the pulling force when the dust cover 1 is released from the first mold 91.

  Further, the connected portions from the inner peripheral surface 24a to the taper straight portion 27c are configured to be smoothly connected. Therefore, it is possible to suppress the lip portion 27 from being caught on the molding surface 91b.

  Therefore, the distortion of the outer peripheral surface of the lip portion 27 (the first arc portion 27a, the second arc portion 27b, and the taper straight portion 27c) is dispersed throughout, and the catch on the first mold 91 is suppressed and the outer periphery of the lip portion 27 is suppressed. It is possible to suppress the occurrence of cracks on the surface.

  As shown in FIG. 8D, the dust cover 1 is extracted from the first mold 91 in a state where the cylindrical portion 24 is separated from the first mold 91.

  The present invention has been described above based on the embodiments. However, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the spirit of the present invention. It can be easily guessed.

  For example, the numerical values (for example, the number, size, angle, etc. of each component) given in the above embodiments are merely examples, and other numerical values can naturally be adopted.

  In each of the above-described embodiments, the case where the single lip portion 27 is formed only at the lower end of the cylindrical portion 24 has been described. However, the present invention is not necessarily limited to this, and a plurality of lips are arranged on the axis O of the cylindrical portion 24. They may be formed at predetermined intervals in the direction.

  In this case, by increasing the number of locations that come into contact with the outer peripheral surface of the cylinder 5, it is possible to reduce the progress of the peeling of the coating at one location on the outer peripheral surface of the cylinder 5.

  In each of the above-described embodiments, the case where the lower end surface 24b and the taper straight portion 27c are configured in a linear shape has been described. However, the present invention is not necessarily limited to this, and the lower end surface 24b and the taper straight portion 27c are arranged in the vertical direction. You may form in the convex one circular arc shape.

  In this case, since the connecting portion P1 between the lower end surface 24b and the taper straight portion 27c is disposed on the curved surface, the pressure on the contact surface increases when the outer peripheral surface of the cylinder 5 contacts the connecting portion P1. Can be suppressed. Therefore, paint peeling of the cylinder 5 can be suppressed.

It is sectional drawing of the suspension mechanism in which the dust cover in 1st Embodiment of this invention was integrated. It is the elements on larger scale of the lip | rip part which expanded and showed the part of A of FIG. It is the elements on larger scale of the 2nd circular-arc part which expanded and showed the part of B of FIG. It is the elements on larger scale of the 2nd circular arc part showing the state where the cylinder contacted the end of the lip part. (A) is sectional drawing of the dust cover in the Va-Va line | wire of FIG. 1, (b) is an outer peripheral surface of a dust cover, and the case where an annular rib part is formed in the position on the back side of a lip | rip part It is sectional drawing of a dust cover. It is sectional drawing of the 1st type | mold, a 2nd type | mold, and a 3rd type | mold in the state where the type | mold was closed. It is sectional drawing of the 1st type | mold, 2nd type | mold, and 3rd type | mold in the state where the mold was divided. It is a state transition diagram showing a state where the lip portion of the dust cover is released, (a) is a state transition diagram showing a state where the vulcanization mold for molding the dust cover is clamped, (B) is a state transition diagram showing a state in which the second mold and the third mold of the vulcanization mold are opened relative to the first mold, and (c) is a diagram illustrating the dust cover from the first mold. It is a state transition diagram showing the state which is going to be extracted, (d) is a state transition diagram which showed the state where the lip part of the dust cover was extracted from the 1st type.

Explanation of symbols

100 Suspension mechanism 1 Dust cover 2 Strut mount (vibration isolation device)
4 Piston rod (piston rod, part of shock absorber)
5 Cylinder (housing, part of shock absorber)
21 Internal fitting (part of the main body)
22 Stopper holder (part of the main body)
23 Bellows (a part of the bellows and cover)
24 Cylindrical part (cylindrical part, part of cover part)
24b Lower end surface (connection surface)
24c outer peripheral surface (the outer peripheral surface of the cylindrical portion)
27 Lip part 27b Second arc part (tip part of lip part)
27c Tapered straight section (taper cross section)
θ1 angle (intersection angle between the imaginary line with the tapered surface extended and the outer peripheral surface)
θ3 angle (intersection angle between connecting surface and outer peripheral surface)

Claims (4)

In a dust cover composed of a rubber-like elastic body, a shock absorber housing is connected to a wheel side and a piston rod of the shock absorber is attached to a vehicle body frame side via a vibration isolation device.
A main body attached to the vibration isolator;
A cylindrical cover part that hangs downward from the main body part and surrounds the outer periphery of the piston rod and housing of the shock absorber,
The cover portion includes a bellows portion connected to the main body portion and configured in a bellows shape, and a cylindrical portion connected to the bellows portion and configured in a cylindrical shape,
The cylindrical portion includes an inner peripheral surface side of the cylindrical portion and a tapered surface that is positioned at a lower end portion in the hanging direction and has a tapered shape that increases in inner diameter as the distance from the main body portion increases. Features dust cover. The cylindrical portion includes a lip portion configured as a protrusion that protrudes radially inward from the inner peripheral surface of the cylindrical portion and is continuous in the circumferential direction.
The tapered surface is constituted by one side surface of the lip portion, and an inner diameter at an end of the tapered surface is configured to be larger than an inner diameter of an inner peripheral surface of the cylindrical portion. The dust cover according to 1.   In a cross-sectional view including the axial center of the cylindrical portion, the tapered surface is configured in a straight line, and the tip portion of the lip portion is configured to be curved in an arc shape convex in the axial direction of the cylindrical portion. The dust cover according to claim 2.   The cylindrical portion includes a connecting surface that connects the outer peripheral surface of the cylindrical portion and the tapered surface, and the crossing angle formed by the connecting surface and the outer peripheral surface is a cross-sectional view including the axial center of the cylindrical portion. 4. The dust cover according to claim 2, wherein the dust cover is configured to have an angle larger than an intersection angle formed by an imaginary line obtained by extending the tapered surface and the outer peripheral surface.

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