Dust boot, method of manufacturing dust boot, and shock absorber

Abstract

A dust boot includes a tubular boot body and an annular flange portion linked to an upper end of the boot body. In an outer side of the flange portion, an angle between the flange portion and a line perpendicular to an axis of the boot body is set to be larger than 0 and smaller than 90.

Claims

1. A method of manufacturing a dust boot for a shock absorber, the shock absorber comprising: a cylinder; a rod configured to move into and out of the cylinder; a rod-side spring seat installed in the rod; a cylinder-side spring seat installed in the cylinder; a suspension spring interposed between the rod-side spring seat and the cylinder-side spring seat; and the dust boot, wherein the dust boot has a tubular boot body provided with an extendable/contractible bellows portion to cover the rod, and an annular flange portion linked to an upper end of the boot body and held between the rod-side spring seat and the suspension spring, wherein the shock absorber further comprises a rubber seat installed in an upper end of the suspension spring and interposed between the flange portion and the suspension spring, and wherein an angle between the flange portion and a line perpendicular to an axis of the boot body in an outer side of the flange portion is set to be larger than 0 degrees and smaller than 90 degrees, said method comprising: forming both the boot body and the flange portion through blow molding.

2. The method of claim 1, the method comprising: inserting a tubular resin material into a mold for integrally molding the boot body and the flange portion; and blowing gas into the resin material to press the resin material to the mold in order to form the dust boot.

3. The method of claim 1, wherein the angle is set to 30 degrees or larger and 60 degrees or smaller.

4. A shock absorber, comprising: a cylinder; a rod configured to move into and out of the cylinder; a rod-side spring seat installed in the rod; a cylinder-side spring seat installed in the cylinder; a suspension spring interposed between the rod-side spring seat and the cylinder-side spring seat; and a dust boot, wherein the dust boot has a tubular boot body provided with an extendable/contractible bellows portion to cover the rod, and an annular flange portion linked to an upper end of the boot body and held between the rod-side spring seat and the suspension spring, wherein an angle between the flange portion and a line perpendicular to an axis of the boot body in an outer side of the flange portion is set to be larger than 0 degrees and smaller than 90 degrees, and wherein the shock absorber further comprises a rubber seat installed in an upper end of the suspension spring and interposed between the flange portion and the suspension spring.

5. The shock absorber according to claim 4, wherein the boot body has a cutaway hole, and the rubber seat has a protrusion fitted to the cutaway hole.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a side view illustrating a shock absorber provided with a dust boot according to an embodiment of the invention;

(2) FIG. 2 is a vertically cross-sectional view illustrating the dust boot; and

(3) FIG. 3 is a diagram for describing a method of manufacturing the dust boot.

DESCRIPTION OF EMBODIMENTS

(4) Embodiments of the present invention will now be described with reference to the accompanying drawings.

(5) As illustrated in FIG. 1, the shock absorber 100 includes a cylinder 4, a rod 5 configured to move into and out of the cylinder 4, a rod-side spring seat 6 installed in the rod 5, a cylinder-side spring seat 7 installed in the cylinder 4, a suspension spring 8 interposed between the rod-side spring seat 6 and the cylinder-side spring seat 7 and disposed in the outer circumferential sides of the cylinder 4 and the rod 5, and a dust boot 1.

(6) The dust boot 1 has a tubular boot body 2 provided with a partially extendable/contractible bellows portion 2a and an annular flange portion 3 linked to an upper end of the boot body 2.

(7) The dust boot 1 is installed in the rod 5 by holding the flange portion 3 between the rod-side spring seat 6 and the suspension spring 8. The dust boot 1 covers the rod 5 while the boot body 2 is disposed in the outer circumferential side of the rod 5.

(8) The cylinder 4 is partitioned into an extension-side chamber and a contraction-side chamber by a piston (not shown) slidably inserted into the inside. A liquid is filled in the extension-side chamber and the contraction-side chamber.

(9) The cylinder-side spring seat 7 is installed in the outer circumference of the cylinder 4. In addition, a cap-shaped bump stopper 9 is fixed to an upper end of the cylinder 4 in FIG. 1.

(10) A lower end of the rod 5 is movably inserted into the cylinder 4 and is connected to the piston inside the cylinder 4. A mount 110 for mounting the shock absorber 100 onto the chassis is installed in the upper end of the rod 5 in FIG. 1.

(11) The rod-side spring seat 6 is rotatably installed in an outer circumference of the mount 110 by interposing a bearing 120. In this manner, the rod-side spring seat 6 can be installed in the rod 5 using the mount 110. Alternatively, the rod-side spring seat 6 may be directly installed in the rod 5.

(12) The rod-side spring seat 6 includes an inner tube 6a and an annular seat portion 6b extending from the upper end of the inner tube 6a in FIG. 1 to the outer circumference. The rod-side spring seat 6 is configured to receive a load from the suspension spring 8 on the seat portion 6b.

(13) A slide ring 11 of the bearing 120 is installed in the upper end of the seat portion 6b in FIG. 1. In addition, a holder 12 configured to rotatably hold the slide ring 11 is installed in the mount 110 side of the seat portion 6b. The bearing 120 includes the sliding ring 11 and the holder 12.

(14) The suspension spring 8 is a coil spring. The suspension spring 8 is interposed between the rod-side spring seat 6 and the cylinder-side spring seat 7 and is disposed in the outer circumferential sides of the cylinder 4 and the rod 5 in order to bias the cylinder 4 and the rod 5 to a mutually separating direction.

(15) Further, a rubber seat 10 is installed in the upper end of the suspension spring 8 in FIG. 1. The rubber seat 10 includes a tubular insertion 10a inserted into the suspension spring 8, an annular seat portion 10b extending from an upper end of the insertion 10a to the outer circumferential side, and a plurality of hook portions 10c hooked from the lower end of the insertion 10a to the outer circumference of the seat portion 10b.

(16) The rubber seat 10 can be installed in the rod-side spring seat 6 by fitting the insertion 10a to the outer circumference of the inner tube 6a of the rod-side spring seat 6. In addition, the inner circumference of the insertion 10a is provided with four protrusions 10d arranged circumferentially at equal intervals.

(17) In order to install the rubber seat 10 in the upper end of the suspension spring 8 in FIG. 1, the wire of the suspension spring 8 is inserted into each hook portion 10c through screwing. In this manner, by inserting the wire of the suspension spring 8 into each hook portion 10c, it is possible to hold the suspension spring 8 without falling even when the suspension spring 8 is broken in the middle.

(18) The shock absorber 100 is provided with a damping passage (not shown) through which the liquid passes between the extension-side chamber and the contraction-side chamber. The shock absorber 100 is configured to apply resistance to a flow of the liquid passing through the damping passage.

(19) In the shock absorber 100, when the rod 5 moves into and out of the cylinder 4, the liquid flows from a compressed chamber to an expanded chamber between the extension-side chamber and the contraction-side chamber by the piston. In this case, a pressure difference is generated between the extension-side chamber and the contraction-side chamber by a pressure loss generated as the liquid passes through the damping passage. As a result, the shock absorber 100 generates a damping force corresponding to this pressure difference to suppress axial movement of the rod 5 relative to the cylinder 4.

(20) Note that a bump stopper rubber 13 is provided on the upper outer circumference of the rod 5 in FIG. 1 beneath the mount 110 oppositely to the bump stopper 9. When the shock absorber 100 is contracted at a certain level, the bump stopper rubber 13 abuts on the bump stopper 9 and is compressed to exert an elastic force for suppressing further contraction of the shock absorber 100.

(21) Subsequently, the dust boot 1 will be described in more detail.

(22) The dust boot 1 is formed of resin and has the boot body 2 and the flange portion 3 as illustrated in FIGS. 1 and 2. The boot body 2 has the bellows portion 2a and a tubular portion 2b provided in the upper end of the bellows portion 2a in FIG. 2. In addition, the tubular portion 2b is provided with four cutaway holes 2c arranged circumferentially at equal intervals.

(23) The flange portion 3 has an annular shape and is linked to the upper end of the tubular portion 2b. In the outer side of the flange portion 3, an angle between the flange portion 3 and a horizontal line H perpendicular to the axis of the boot body 2 is set to 30 according to this embodiment.

(24) The dust boot 1 is installed in the rod 5 by holding the flange portion 3 between the rod-side spring seat 6 and the suspension spring 8. When the flange portion 3 is held between the rod-side spring seat 6 and the suspension spring 8, the flange portion 3 is widened and pressed to match the seat portion 6b of the rod-side spring seat 6.

(25) More specifically, according to this embodiment, the dust boot 1 is installed in the rubber seat 10 by inserting and fitting the tubular portion 2b into the rubber seat 10. The cutaway holes 2c are provided to face the protrusions 10d of the rubber seat 10.

(26) Therefore, when the tubular portion 2b of the boot body 2 is inserted into the insertion 10a of the rubber seat 10, each protrusion 10d is fitted to each corresponding cutaway hole 2c. As a result, the dust boot 1 is installed in the rubber seat 10 in a retaining state. Note that the number of the protrusions 10d and the number of the cutaway holes 2c may be set to any number.

(27) If the insertion 10a of the rubber seat 10 is fitted to the outer circumference of the inner tube 6a of the rod-side spring seat 6 while the dust boot 1 is placed, the rubber seat 10 tightly holds the inner tube 6a such that the tubular portion 2b is pressed to the inner tube 6a. As a result, the dust boot 1 is installed in the rod-side spring seat 6.

(28) The flange portion 3 is interposed between the seat portion 10b of the rubber seat 10 and the seat portion 6b of the rod-side spring seat 6. If the suspension spring 8 installed with the rubber seat 10 is interposed between the rod-side spring seat 6 and the cylinder-side spring seat 7, the flange portion 3 is pressed to the seat portion 6b through the seat portion 10b by virtue of a spring force of the suspension spring 8. As a result, the flange portion 3 is fixed to the rod-side spring seat 6 while it tightly abuts on the seat portion 6b.

(29) Alternatively, the rubber seat 10 may also be removed. However, using the rubber seat 10, it is possible to prevent a termination end of the suspension spring 8 from coming into direct contact with the flange portion 3 and allow the entire flange portion 3 to tightly abut on the seat portion 6b of the rod-side spring seat 6. Furthermore, it is possible to facilitate positioning of the dust boot 1 relative to the rod-side spring seat 6.

(30) The lower end of the boot body 2 in FIG. 1 corresponding to the lower end of the dust boot 1 is fitted to the outer circumference of the bump stopper 9. Therefore, during an extending/contracting of the shock absorber 100 in which the rod 5 is vertically moved with respect to the cylinder 4 in FIG. 1, the dust boot 1 extends or contracts in response to the extension or contraction of the shock absorber 100 to cover the rod 5 at all times. As a result, it is possible to protect a sliding surface of the outer circumferential surface of the rod 5.

(31) Subsequently, a process of manufacturing the dust boot 1 will be described.

(32) The dust boot 1 is manufactured through blow molding. A mold for manufacturing the dust boot 1 is divided into a pair of halves 20 and 20 as illustrated in FIG. 3. Inside the mold 20, recesses 20a are formed to match the shape of the dust boot 1 in order to mold both the boot body 2 and the flange portion 3 of the dust boot 1 at once.

(33) A heated tubular resin material J is inserted into the mold 20, and air is blown inside of the resin material J to inflate it. As a result, the resin material J is pressed to the recesses 20a, so that the dust boot 1 is molded.

(34) As described above, the flange portion 3 is linked to the boot body 2 at an angle of 30 with respect to the horizontal line H. For this reason, the amount of the resin material J used to form the flange portion 3 increases even by forming the dust boot 1 through the blow molding, compared to a case where the flange portion 3 has an angle of 0 with respect to the horizontal line H, that is, the flange portion 3 is in parallel with the horizontal line H. Therefore, it is possible to increase the thickness of the flange portion 3 enough to secure the strength.

(35) In this manner, if the dust boot 1 is manufactured through blow molding by setting the angle between the flange portion 3 and the horizontal line H to be larger than 0 and smaller than 90, it is possible to increase the thickness of the flange portion 3, compared to a case where the angle between the flange portion 3 and the horizontal line H is set to 0. Therefore, it is possible to secure the strength of the flange portion 3.

(36) In this regard, as the angle between the flange portion 3 and the horizontal line H approaches zero, deformation of the flange portion 3 widened to match the seat portion 6b of the rod-side spring seat 6 by holding the flange portion 3 between the rod-side spring seat 6 and the suspension spring 8 is reduced. For this reason, it is possible to facilitate an assembly work for holding the flange portion 3 between the rod-side spring seat 6 and the suspension spring 8. Meanwhile, the thickness of the flange portion 3 tends to decrease.

(37) In contrast, as the angle between the flange portion 3 and the horizontal line H approaches 90, deformation of the flange portion 3 widened to match the seat portion 6b of the rod-side spring seat 6 by holding the flange portion 3 between the rod-side spring seat 6 and the suspension spring 8 becomes serious. For this reason, an assembly work for holding the flange portion 3 between the rod-side spring seat 6 and the suspension spring 8 becomes difficult. Meanwhile, the thickness of the flange portion 3 tends to increase. This is advantageous in terms of the strength.

(38) That is, a tradeoff relationship is established between the easiness of the assembly work and the strength of the flange portion 3. However, if the angle between the flange portion 3 and the horizontal line H in the outer side of the dust boot 1 is set to be 30 and larger and 60 or smaller, it is possible to secure both the easiness of the assembly work for holding the flange portion 3 between the rod-side spring seat 6 and the suspension spring 8 and the strength of the flange portion 3. That is, it is possible to guarantee both the easiness of the assembly work and the strength of the flange portion 3.

(39) As described above, in the dust boot 1 according to this embodiment, the angle between the flange portion 3 and the horizontal line is set to be larger than 0 and smaller than 90. As a result, it is possible to secure the thickness of the flange portion 3 even by forming the dust boot 1 through blow molding. Therefore, it is possible to employ inexpensive blow molding in manufacturing of the dust boot 1 while securing the strength.

(40) Using the method of manufacturing the dust boot 1 according to this embodiment, it is possible to employ inexpensive blow molding in manufacturing of the dust boot 1 while securing the strength.

(41) In addition, the shock absorber 100 according to this embodiment has the dust boot 1 manufactured through inexpensive blow molding while securing the strength. Therefore, it is possible to manufacture the shock absorber 100 at a low cost as well.

(42) Embodiments of this invention were described above, but the above embodiments are merely examples of applications of this invention, and the technical scope of this invention is not limited to the specific constitutions of the above embodiments.

(43) This application claims priority based on Japanese Patent Application No. 2014-67925 filed with the Japan Patent Office on Mar. 28, 2014, the entire contents of which are incorporated into this specification.