Shock absorber, manufacturing method therefor, and front fork

Abstract

A shock absorber (10) has a bracket (20) in which a columnar hole (22b), which is a cylindrical hole, is formed, and a cylindrical tube (31) that is supported by the bracket (20) and extends downward from the columnar hole (22b). A fixing part (F1) in which the tube (31) is fixed to the bracket (20) is formed at a position avoiding the lower end of the bracket (20). Preferably, the fixing part (F1) is configured by welding the upper end of the tube (31) to the bracket (20).

Description

Shock absorber, manufacturing method thereof, and front fork

[0001] The present invention relates to a manufacturing technique for a shock absorber including a front fork.

[0002] 2. Description of the Related Art A conventional technique relating to a shock absorber, particularly a front fork of a saddle-ride type vehicle, is disclosed in Japanese Patent Application Laid-Open No. 2003-222999.

[0003] The front fork as shown in Patent Document 1 includes a bracket that rotates together with the handle pipe when it is rotated, and a shock absorber body whose upper end is inserted into the bracket and capable of generating a damping force. The front wheel is connected to the lower end of the shock absorber body.

[0004] The shock absorber body includes a cylindrical tube at its upper end, which is inserted into a bracket. The portion of the bracket where the tube is inserted is welded, thereby fixing the tube to the bracket.

[0005] Japanese Patent Application Publication No. 8-295278

[0006] When a saddle-type vehicle is traveling, front-rear and left-right forces may be applied to the front wheel due to road irregularities, etc. These front-rear and left-right forces act to bend the tube relative to the bracket. Applying a large load to the portion where the tube is joined to the bracket is undesirable from the perspective of extending the life of the tube. In other words, it is desirable to reduce the load on the fixing portion where the tube is fixed to the bracket.

[0007] An object of the present invention is to provide a shock absorber that can reduce the load on the fixed portion.

[0008] As a result of extensive research, the inventors have found that the load on the fixing portion can be reduced by forming the fixing portion at a position that avoids the lower end of the bracket. The present invention was completed based on this finding.

[0009] The present disclosure will be described below.

[0010] According to the present disclosure, there is provided a shock absorber having: a bracket having a cylindrical hole portion which is a cylindrical hole; and a cylindrical tube supported by the bracket and extending downward from the cylindrical hole portion, wherein a fixing portion where the tube is fixed to the bracket is formed at a position that avoids the lower end of the bracket.

[0011] According to the present invention, it is possible to provide a shock absorber that can reduce the load applied to the fixed portion.

[0012] Fig. 3 is a front view showing a main part of a shock absorber according to Example 1. Fig. 4 is an enlarged view of a main part of Fig. 1. Fig. 5 is a diagram for explaining a manufacturing method of the shock absorber shown in Fig. 2. Fig. 6 is an enlarged cross-sectional view of a main part of a shock absorber according to Example 2. Fig. 7 is an enlarged cross-sectional view of a main part of a shock absorber according to Example 3. Fig. 8 is an enlarged cross-sectional view of a main part of a shock absorber according to Example 4. Fig. 9 is an enlarged cross-sectional view of a main part of a shock absorber according to Example 5.

[0013] An embodiment of the present invention will be described below with reference to the accompanying drawings. In the description, left and right refer to the left and right relative to the occupant of the saddle-ride type vehicle, and front and rear refer to the front and rear relative to the traveling direction of the saddle-ride type vehicle. In the drawings, Fr indicates the front, Rr indicates the rear, Le indicates the left as seen from the occupant, Ri indicates the right as seen from the occupant, Up indicates the top, and Dn indicates the bottom. The embodiment shown in the accompanying drawings is an example of the present invention, and the present invention is not limited to this embodiment.

[0014] <Example 1> Please refer to Figure 1. Figure 1 shows the main parts of a shock absorber 10. The shock absorber 10 is used, for example, as a front fork of a saddle-ride type vehicle on which a rider sits astride. The shock absorber 10 has a bracket 20 that rotates in conjunction with the rider operating the handlebars, and shock absorber bodies 30, 30 that are supported by the bracket 20 and connected to the front wheel.

[0015] The number of shock absorber bodies 30, 30 supported by the bracket 20 may be one.

[0016] The bracket 20 has a round rod-shaped upper bracket 21 connected to the handlebars, and a lower bracket 22 into which the lower end of the upper bracket 21 is inserted and which supports the shock absorber bodies 30, 30.

[0017] The lower bracket 22 is formed with an upper bracket insertion hole 22a into which the upper bracket 21 is inserted, and a shock absorber body insertion hole 22b into which the shock absorber body 30 is inserted. The upper bracket insertion hole 22a and the shock absorber body insertion hole 22b are both cylindrical holes. Hereinafter, the shock absorber body insertion hole 22b may be referred to as the cylindrical hole 22b.

[0018] The upper bracket insertion hole 22a does not necessarily have to be a cylindrical through-hole, but may be a hole with a bottom, an elliptical hole, or a polygonal hole.

[0019] See Figure 2. The shock absorber body 30 is shown only in the form of a cylindrical tube 31 and a lid 32 that closes the upper end of the tube 31 as its essential parts. As long as the shock absorber body 30 generates a damping force when it expands and contracts, the fluid filled inside the tube 31 and the relative positions of the upper and lower tubes, such as an upright type or an inverted type, can be selected arbitrarily.

[0020] In addition to the tube 31 and the cover 32, the shock absorber body 30 has a lower cylinder positioned below the tube 31 that can move up and down relative to the tube 31, a piston located inside either the upper or lower tube that generates a damping force when fluid passes through, a spring that acts to return the tube 31, etc. to a predetermined position, and any of these known configurations can be adopted.

[0021] The upper end of the tube 31 is located substantially flush with the upper surface of the bracket 20, and the tube 31 is joined to the bracket 20 by welding. The portion where the tube 31 is fixed to the bracket 20 is hereinafter referred to as the "fixed portion F1." In FIG. 2 , the fixed portion F1 is formed by welding the upper end of the tube 31 to the bracket 20. The fixed portion F1 is formed continuously on the upper surface of the bracket 20 and the upper end surface of the tube 31, and is formed around the entire upper end of the tube 31. It can also be said that the fixed portion F1 is formed at a position that avoids the lower end of the bracket 20.

[0022] The upper end of the tube 31 may be located below or above the upper surface of the bracket 20. When the upper end of the tube 31 is located below the upper surface of the bracket 20, a fixing portion is formed from the cylindrical hole 22b to the upper end surface of the tube 31. When the upper end of the tube 31 is located above the upper surface of the bracket 20, a fixing portion is formed from the upper surface of the bracket 20 to the side surface of the tube 31.

[0023] The upper surface of the lid 32 is positioned substantially flush with the upper surface of the bracket 20 and the upper end of the tube 31, and the lid 32 is joined to the tube 31 by welding.

[0024] The upper surface of the lid 32 may be located below the upper end surface of the tube 31 or may be located above the upper end surface of the tube 31 .

[0025] Please refer to Figure 3. A manufacturing method of the shock absorber 10 (see Figure 2) will be described. To manufacture the shock absorber 10, a lid insertion process is performed in which the lid 32 is inserted into the upper end of the tube 31 by press-fitting, and a tube insertion process is performed in which the tube 31 is inserted into the upper end of the bracket 20. Either the lid insertion process or the tube insertion process may be performed first.

[0026] The lid inserting step and the tube inserting step may be performed by a method other than press fitting. Also, the lid inserting step and the tube inserting step may be performed by different insertion methods.

[0027] Next, a welding process is performed in which the lid 32 is welded to the tube 31 and the tube 31 is welded to the bracket 20. The welding process is performed by laser welding using, for example, a laser welder 41. The lid 32 and the tube 31 are preferably welded over their entire circumferences. Either the lid 32 or the tube 31 may be welded first, but it is preferable to perform these welding processes consecutively or simultaneously.

[0028] The welding may be performed by a welding method other than laser welding. That is, any welding method may be selected. The lid 32 or the tube 31 may be welded by an intermittent welding method.

[0029] Second Embodiment Next, a second embodiment will be described with reference to the drawings.

[0030] Please refer to Figure 4. In the shock absorber 10A according to the second embodiment, the position at which the tube 31A of the shock absorber main body 30A is fixed is different from that of the shock absorber 10 described in Figure 2. The other basic configuration is the same as that of the shock absorber 10. For the configuration that is the same as that of the shock absorber 10, the same reference numerals will be used and detailed description will be omitted as appropriate.

[0031] The upper end of the tube 31A is located at a position lower than the upper surface of the bracket 20. On the other hand, the upper surface of the lid 32A is located at approximately the same height as the upper surface of the bracket 20. The area surrounded by the bracket 20, the tube 31A, and the lid 32A is filled with a bead. The fixing portion F2 is formed by welding the tube 31A to the bracket 20.

[0032] Third Embodiment Next, a third embodiment will be described with reference to the drawings.

[0033] See Figure 5. The shock absorber 10B according to the third embodiment uses fall suppression members 51B and 52B that suppress the tube 31B from falling off the bracket 20B. The other basic configuration is the same as that of the shock absorber 10. The same reference numerals are used for the components that are the same as those of the shock absorber 10, and detailed descriptions thereof will be omitted as appropriate.

[0034] The lower bracket 22B constituting the bracket 20B is formed with a first through-hole portion 22Bc penetrating radially from the outer peripheral surface toward the axis, a second through-hole portion 22Bd penetrating tangentially to the outer peripheral surface, and a seal storage groove 22Be for storing the seal member 53B.

[0035] The outer surface of the tube 31B that constitutes the shock absorber main body 30B is formed with a first tube side hole portion 31Ba, which is a bottomed hole that continues from the first through hole portion 22Bc and has the same inner diameter as the first through hole portion 22Bc, and a second tube side hole portion 31Bb that is opened along the second through hole portion 22Bd and is formed in a circular shape that continues from the second through hole portion 22Bd.

[0036] The fall suppression member 51B is formed of a cylindrical pin that passes through the first through-hole 22Bc and has a tip that reaches the first tube-side hole 31Ba.

[0037] The other fall-preventing member 52B is formed of a cylindrical pin and passes through both the second through-hole 22Bd and the second tube-side hole 31Bb.

[0038] By inserting the fall suppression members 51B and 52B, the tube 31B can be prevented from falling even if a load is applied to the tube 31B in the falling direction. At least one of the fall suppression members 51B and 52B needs to be used. The fall suppression members 51B and 52B can also be configured with set screws or the like. Furthermore, different types of fall suppression members 51B and 52B can be combined.

[0039] The fixing portion F3 at which the tube 31B is fixed to the bracket 20B is composed of fall suppression members 51B and 52B.

[0040] Fourth Embodiment Next, a fourth embodiment will be described with reference to the drawings.

[0041] See Fig. 6. A shock absorber 10C according to the fourth embodiment has a shock absorber main body 30C screwed to a bracket 20C. The other basic configuration is the same as that of the shock absorber 10. The same reference numerals will be used for the components common to the shock absorber 10, and detailed descriptions will be omitted as appropriate.

[0042] A lower bracket 22C constituting the bracket 20C has a female screw formed along a cylindrical hole 22Cb.

[0043] The outer peripheral surface of the upper end of the tube 31C is formed with a male screw, and the upper end of the tube 31C is fastened to the cylindrical hole portion 22Cb.

[0044] A ring-shaped positioning ring 54C is fixed to the upper end of the cylindrical hole 22Cb to restrict upward movement of the tube 31C and determine the mounting position of the tube 31C. A ring lid 55C is provided on the inner periphery of the positioning ring 54C to prevent water droplets and the like from entering the interior. The positioning ring 54C and the ring lid 55C may be welded to the bracket 20C.

[0045] The fixing portion F4 at which the tube 31C is fixed to the bracket 20C is formed by fastening the tube 31C to the bracket 20C with screws.

[0046] Fifth Embodiment Next, a fifth embodiment will be described with reference to the drawings.

[0047] See Figure 7. A shock absorber 10D according to the fifth embodiment has a configuration in which a shock absorber body 30 is adhered to a bracket 20 with an adhesive. Other basic configurations are common to the shock absorber 10. For configurations common to the shock absorber 10, the same reference numerals are used and detailed descriptions are omitted as appropriate.

[0048] The shock absorber 10D is manufactured by applying adhesive to the outer peripheral surface of the lid 32, press-fitting it onto the upper end of the tube 31, and then applying adhesive to the outer peripheral surface near the upper end of the tube 31 and press-fitting it into the cylindrical hole 22b. In other words, the shock absorber 10D is manufactured through an adhesive application process and a press-fitting process.

[0049] The fixing portion F5 at which the tube 31 is fixed to the bracket 20 is formed by adhesively bonding the tube 31 to the bracket 20.

[0050] The shock absorber 10 described above will be summarized below.

[0051] Referring to Figure 2, shock absorber 10 has bracket 20 having cylindrical hole 22b, which is a cylindrical hole, and tube 31 that is supported by bracket 20 and extends downward from cylindrical hole 22b. Fixing portion F1 where tube 31 is fixed to bracket 20 is formed at a position that avoids the lower end of bracket 20.

[0052] A large load is applied to the lower end of the portion of the bracket 20 where the tube 31 is inserted. The fixing portion F1 is provided to avoid this portion where a large load is applied. This reduces the load applied to the fixing portion F1. The same applies to the shock absorbers 10A, 10B, 10C, and 10D (see FIGS. 4 to 7).

[0053] Second, in the first shock absorber 10, the fixing portion F1 is configured by welding the upper end of the tube 31 to the bracket 20. This allows the tube 31 to be fixed to the bracket 20 with high strength. In addition, the bead fills the gap between the tube 31 and the bracket 20, preventing water from entering. The same applies to the shock absorber 10A (see FIG. 4).

[0054] Thirdly, in the second shock absorber 10, the upper end of the tube 31 is positioned on approximately the same plane as the upper surface of the bracket 20. Various welding methods such as laser welding can be employed, and are preferable.

[0055] Fourth, the third shock absorber 10 further includes a lid 32 that closes the upper end of the tube 31, and the upper surface of the lid 32 is positioned approximately flush with the upper surface of the bracket 20. The bracket 20, the tube 31, and the lid 32 can be easily arranged nearby and welded together.

[0056] See Fig. 5. Fifth, in any of the first to fourth shock absorbers 10B, the fixing portion F3 is configured with a fall-prevention member 51B that is inserted from the bracket 20B to the tube 31B and prevents the tube 31B from falling off the bracket 20B. The portion into which the fall-prevention member 51B is inserted does not suffer from distortion due to heat that may occur during welding.

[0057] See Figure 6. Sixth, in any of the first to fifth shock absorbers 10C, the fixing portion F4 is configured by fastening the tube 31C to the bracket 20C with screws. This simplifies the attachment of the tube 31C to the bracket 20C, and prevents distortion of the screw-fastened portion due to heat that may occur during welding.

[0058] See Figure 7. Seventh, in any of the first to sixth shock absorbers 10D, the fixing portion F5 is configured by bonding the tube 31 to the bracket 20. This simplifies the attachment of the tube 31 to the bracket 20, and prevents distortion of the bonded portion due to heat that may occur during welding.

[0059] See Figure 3. Eighth, in the manufacturing method for a shock absorber for manufacturing any one of the first to fourth shock absorbers 10, the tube insertion step of inserting the tube 31 into the cylindrical hole portion 22b is performed by press-fitting. Since there is no need to perform splitting or threading, the manufacturing cost of the shock absorber 10 can be reduced. The same applies to the shock absorbers 10A, 10B, and 10D.

[0060] Ninth, in the shock absorber manufacturing method for manufacturing any one of the first to fourth shock absorbers 10 or the eighth shock absorber manufacturing method, the welding step of welding the tube 31 to the bracket 20 is performed by laser welding. By using laser welding, the welding step can be completed in a short time, and the shock absorber 10 can be manufactured in a short time. The same applies to the shock absorbers 10B and 10D.

[0061] Tenth, in the ninth shock absorber manufacturing method, the welding process is performed around the entire circumference of the upper end of the tube 31. This makes it possible to prevent water from entering between the bracket 20 and the tube 31.

[0062] Eleventh, any one of the first to seventh shock absorbers 10 is a front fork that is connected to the front wheel of a saddle-ride type vehicle.

[0063] Although the shock absorber according to the present invention has been described as being mounted on a front fork, it can also be applied to a rear shock absorber and is not limited to these types. In other words, the present invention is not limited to the embodiments as long as the functions and effects of the present invention are achieved.

[0064] The shock absorber of the present invention is suitable for a front fork.

[0065] 10, 10A, 10B, 10C, 10D... Shock absorber 20, 20B, 20C... Bracket 22b, 22Cb... Shock absorber body insertion hole portion (cylindrical hole portion) 31, 31A, 31B, 31C... Tube 32, 32A... Cover body F1, F2, F3, F4, F5... Fixing portion

Claims

1. A shock absorber comprising: a bracket with a cylindrical hole; and a tubular tube supported by the bracket and extending downward from the cylindrical hole, wherein the fixing portion where the tube is fixed to the bracket is formed at a position that avoids the lower end of the bracket.

2. The shock absorber according to claim 1, wherein the fixing portion is formed by welding the upper end of the tube to the bracket.

3. The shock absorber according to claim 2, wherein the upper end of said tube is positioned on approximately the same plane as the upper surface of said bracket.

4. The shock absorber according to claim 3, further comprising a lid that closes the upper end of said tube, the upper surface of said lid being positioned substantially flush with the upper surface of said bracket.

5. A shock absorber according to claim 1, wherein the fixing portion is constituted by a fall prevention member that is inserted from the bracket to the tube and prevents the tube from falling from the bracket.

6. The shock absorber according to claim 1, wherein the fixing portion is formed by fastening the tube to the bracket with screws.

7. The shock absorber according to claim 1, wherein the fixing portion is formed by bonding the tube to the bracket.

8. A method for manufacturing a shock absorber according to claim 3, wherein the tube insertion step of inserting the tube into the cylindrical hole is carried out by press-fitting.

9. A method for manufacturing a shock absorber according to claim 3, wherein the welding step of welding the tube to the bracket is performed by laser welding.

10. The method for manufacturing a shock absorber according to claim 9, wherein the welding step is performed around the entire circumference of the upper end of the tube.

11. The shock absorber described in claim 1 is a front fork used by connecting it to the front wheel of a saddle-ride type vehicle.

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