JPH02142939A - Double cylinder type hydraulic shock absorber - Google Patents

Abstract

PURPOSE:To eliminate welding work, and thereby obtain a hydraulic shock absorber excellent in reliability at low cost by monolithically forming a suspension spring receiving projection on the circumferential wall of an outer cylinder at its out side in the radial direction. CONSTITUTION:A lower spring receiving projection 20A which supports the lower end of a coil spring acting as a suspension spring 9 is monolithically formed on the wall surface of an outer cylinder 20. The projection 20 is formed in such a way that a part of the outer cylinder 20 is projected outward in the radial direction by means of water pressure forming, squeeze forming, press forming and the like. By this constitution, it is possible to eliminate welding work, to contrive to reduce cost so as to obtain a double cylinder type hydraulic shock absorber which is excellent in wear resistance, heat radiating property and reliability.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a double-tube hydraulic shock absorber suitable for use in a vehicle suspension system.

[Conventional technology]

Generally, a double-tube hydraulic shock absorber is used to provide a damping function to a suspension system, and when this double-tube hydraulic shock absorber is used in a vehicle suspension system, for example, as shown in Fig. 8, will be installed on the The suspension system shown in this figure is used for the rear wheels of a vehicle, and 1 in the figure indicates a trailing arm, and one end of the trailing arm 1 is attached to a vehicle body panel 2.
is rotatably attached to. The other end of the trailing arm 1 rotatably supports an axle shaft 4 that drives wheels 3. Reference numeral 5 indicates a double-tube hydraulic shock absorber, whose lower end is supported by the other end of the trailing arm 1, and whose upper end is supported by the vehicle body panel 2.
supported on the side. Reference numeral 7 indicates a lower spring receiver that supports the lower side of a coil spring 9, which will be described later.The lower spring receiver 7 is installed due to a reduction in space as suspension systems become more complex, such as in recent multi-link suspensions. Correspondingly, to save space,
It is directly fixed to the hydraulic shock absorber 5. Reference numeral 8 indicates an upper spring receiver that supports the upper side of the coil spring 9, and the upper spring receiver 8 is fixed to the vehicle body panel 2. And 9
indicates a coil spring as a suspension spring, and the coil spring 9 is supported between the hydraulic shock absorber 5 and the vehicle body panel 2 with its upper and lower ends supported by the upper spring receiver 8 and the lower spring receiver 7. is attached to. In general, the double cylinder hydraulic shock absorber 5 includes an outer cylinder lO, an inner cylinder 11 mounted inside the outer cylinder 10 and filled with hydraulic oil, and an inner cylinder 10, as shown in FIG. It is slidably provided inside the cylinder 11 and has a damping valve (not shown) inside, and the inside of the inner cylinder 11 is connected to an upper liquid chamber 11A and a lower liquid chamber 11.
A piston 12 partitioned into B and one end side is the piston 12.
a piston rod 13 fixed to and extending upward from the outer cylinder 10 at the other end; a surrounding liquid chamber 14 formed between the outer cylinder lO and the inner cylinder 11 and filled with hydraulic oil; It is comprised of a bottom valve (not shown) provided at the lower end of the outer cylinder 10 to regulate movement of hydraulic oil between the lower liquid chamber 11B and the surrounding liquid chamber 14. In addition, 1
Reference numeral 5 indicates an attachment eye for attaching the hydraulic shock absorber 5 to the trailing arm l. As shown in FIG. 8, the upper end of the piston rod 13 of the hydraulic shock absorber 5 is swingably attached to an upper spring receiver 8 fixed to the vehicle body panel 2 via a bushing 16. The lower end of the hydraulic shock absorber 5 is swingably attached to the other end of the trailing arm l via an eye 15. The structure of the lower spring receiver 7 that supports the lower side of the coil spring 9 is, for example,
As described in Publication No. 7606 (see FIG. 9), the outer cylinder 1
There is a known device that is integrally attached to the 0 by welding (first conventional example). Further, as described in Japanese Utility Model Application No. 62-170844 (see Fig. 10), a plurality of engagement protrusions 17 are formed on the outer periphery of the outer cylinder 10', and the engagement protrusions 17 are provided with a lower spring receiver. 7′
There is one that is attached by press-fitting (second conventional example). Furthermore, as shown in FIG. 11, a device in which a cylindrical lower spring receiver 7'' is provided on the outer cylinder 10'' is also known. The lower spring receiver 7'' is formed into a cylindrical shape with a lid, and has an insertion hole 7''B into which the piston rod 13 is inserted.
``C'' and a flange portion 7-D formed at the lower end of the cylindrical portion 7''C. (Third Conventional Example). [Problems to be Solved by the Invention] However, each of the above-mentioned conventional techniques has its own problems. In the case of the first conventional example, the lower spring Welding work must be performed to fix the receiver 7 to the outer cylinder 10, which increases the work cost.Furthermore, the welded part is prone to rust, and if the welded part is uneven, the installation of the lower spring receiver 7 will be difficult. becomes weaker,
Inferior in terms of durability. Therefore, there is a problem that the reliability of the hydraulic shock absorber 5 is poor. In the case of the second conventional example, a process of forming the engagement protrusion 17 on the outer cylinder 10' and a process of press-fitting the lower spring receiver 7' into the engagement protrusion 17 are required, and in some cases correction painting may be applied. In some cases, it may be necessary to do so, which increases work costs. Also,
Since the lower spring receiver 7' is simply press-fitted into the engagement protrusion 17, there is a problem in that it may come off upward in some cases. In the case of the third conventional example, since the shape of the lower spring receiver 7'' is complicated and large, there is a problem that the manufacturing cost of this part increases.The present invention has been made in view of the problems of the above-mentioned conventional technology. An object of the present invention is to provide a double-tube hydraulic shock absorber that is low in cost and has excellent durability and reliability. [Means for Solving the Problems] The present invention is adopted to solve the above-mentioned problems. The feature of this structure is that a spring receiving protrusion that protrudes radially outward and serves as a spring receiver for the suspension spring is integrally formed on the peripheral wall of the outer cylinder. Since the receiving protrusion is integrally formed with the outer cylinder, there is no need to attach a spring receiver made of a separate member to the outer cylinder, welding work, etc., and the strength is increased, improving the reliability of the hydraulic shock absorber. [Example] Embodiments of the present invention will be described below based on FIGS. 1 to 7. The suspension system to which the double-tube hydraulic shock absorber of this embodiment is mounted is based on the prior art described based on FIG. 8. Also, since the structure of the double-tube hydraulic shock absorber is almost the same as that of the prior art, the same reference numerals are given to the same members and the explanation is omitted. First, in FIG. In the outer cylinder in this embodiment, a lower spring receiving projection 2OA that supports the lower end of the coil spring 9 as a suspension spring is integrally molded on the peripheral wall of the outer cylinder 20. 2OA is formed by protruding a part of the outer cylinder 20 outward in the radial direction. Methods for forming the lower spring receiving protrusion 2OA include a hydraulic molding method, a squeezing molding method, a press molding method, etc. First, FIGS. 2(A) and 2(B) show the case where the outer cylinder 20 is molded by the water pressure forming method as the first manufacturing method. A pipe material 21 that is longer in diameter than the outer cylinder 20 is used.For the hydroforming method, two pipe materials are used, each having a cylindrical space and an annular groove 22A in a portion corresponding to the lower spring receiving projection 2OA. The split outer mold 22.22 and the outer mold 2
A lower compression member 23 and an upper compression member 24 are disposed above and below the tubes 2 and 22 and compress the tube material 21 from above and below. Next, a hydroforming method using the above material and mold will be described. First, as shown in FIG. 2(A), the tube material 21 is placed in the outer mold 2
2 and 22 and placed on the lower compression member 23. Then, the liquid 25 is injected into the tube material 21, and the upper compression member 24 is brought into contact with the upper side of the tube material 21. Or the pipe material 21
is supported between the lower compression member 23 and the upper compression member 24, and a liquid 25 is injected into the inside thereof, and the two-split outer molds 22, 22 are arranged so as to surround the pipe material 21. Next, as shown in FIG. 2(B), the tube material 21 is compressed from above and below by the lower compression member 23 and the upper compression member 24 while supporting the outer mold 22°22. At this time, the tube material 21 that is longer than the outer molds 22, 22 is
2, the length above and below 22, hl (see Figure 2 (A))
This length is hl. The tube material 21 is pushed into the outer molds 22, 22 by 62 minutes. At the same time, the liquid 25 inside the tube 21 is compressed to a high pressure, and tries to spread the tube 21 open. Then, this pressure pushes the pipe material 21 outward in the radial direction in the portion of the annular groove 22A of the pipe material 21 that is not supported from the outside by the outer mold 22.22, and the lower spring receiving protrusion 2OA is formed. . At this time, the tube material 21 is pushed into the outer mold 21 by a length corresponding to the amount pushed and expanded by the annular groove 22A, so that the wall thickness of the portion of the tube material 21 that forms the lower spring receiving protrusion 2OA is can be molded to approximately the same thickness as the other parts. Next, the squeeze molding method as the second manufacturing method is shown in Figure 3 (
The explanation will be based on A), (B), and (C). When this squeeze forming method is used, a tube material 31 having a larger diameter than the outer cylinder 20 and longer than the outer cylinder 20 is used. Because of the squeezing molding method, a lower squeeze is formed in which the inner diameter t is the same size as the outer diameter of the outer cylinder 20, and the upper opening 32A is formed in the same shape as the lower part of the lower spring receiving projection 2OA. The mold 32 has an inner diameter t2 the same size as the outer diameter of the outer cylinder 20, and a lower opening 33A is formed in the same shape as the upper part of the lower spring receiving protrusion 2OA. An upper squeeze die 33 is used which forms the outer diameter of the lower spring receiving projection 2OA when the squeeze die 32 is aligned with the upper opening 32A. Next, a squeeze molding method using the above material and mold will be described. First, as shown in FIG. 3(A), the upper opening 32A of the lower squeeze mold 32 and the lower opening 33 of the upper squeeze mold 33
A tube material 31 is installed between the A and A. Next, the lower squeeze mold 32 and the upper squeeze mold 33 are compressed together to squeeze the tube material 31 from above and below, and as shown in FIG.
(At this time, the length Ll of the tube material 31 is the sum of the length L2 of the lower squeeze mold 32 and the length L3 of the upper squeeze mold 33. The portions longer than the squeeze lengths Li and Lx are pushed out by the upper opening 32A and the lower opening 33A of each squeeze mold 32, 33.Then, each opening of the tube 31 As shown in FIG. 3(C), the portions that are pushed apart by 32A and 33A are the openings 32 when the squeeze dies 32 and 33 come into contact with each other.
A. The lower spring receiving protrusion 2OA is molded to match the shape of 33A. Note that in this case, the diameter of the tube material 31 is reduced and its wall thickness increases, so a material with a wall thickness that takes this into account is selected. Further, in this molding method, the lower spring receiving protrusion 2OA is squeeze-molded in one stage, but it may be squeeze-molded in multiple stages, for example, by sequentially finding and squeezing in three stages using three squeeze molds. Next, a press molding method as a third manufacturing method will be explained. This press forming method includes a divided press method and a non-divided press method. In the case of the split press method shown in FIG. 4, a plate material is used which is flat and has a bulge in the portion that will become the lower spring receiving projection 2OA. Then, a press machine is used to form half members 41 and 42 in which the outer cylinder 20 is cut in half from the above-mentioned plate material. Next, a divisional press working method using the above-mentioned plate material and press machine will be described. First, as shown in FIG. 4, a plate material having a bulge in the portion that will become the spring receiving projection 2OA is molded into two half members 41 and 42 using a press machine. These half members 41 and 42 each have portions 41A and 42A that become the lower spring receiving protrusion 2OA of the outer cylinder 20,
Half-split cylinder parts 41B and 42B are the upper part of the outer cylinder 20 bordering on the lower spring receiving projection 2OA, and half-split cylinder parts 41B and 42B are the lower part of the outer cylinder 20 bordering on the lower spring receiving projection 2OA. It is composed of cylindrical parts 41C and 42C. Then, these half members 41 and 42 are aligned with each other, and the joint parts are joined by seam welding or the like, and the outer cylinder 20 of the hydraulic shock absorber 5 is assembled.
to form. Next, a non-divided press working method will be explained as a fourth manufacturing method. In the case of the non-divided press working method shown in FIGS. 5 to 7, a flat plate material 51 having a flat plate shape and having a flat bulge 51A in a portion that will become the lower spring receiving protrusion 2OA is used. Then, a press machine is used to press the flat plate material 51 into a cylindrical shape having a bulge corresponding to the lower spring receiving projection 2OA. Next, a non-dividing press working method using the flat plate material 51 and a press machine will be described. First, make a flat bulge 5 on the part that will become the spring receiving protrusion 2OA.
A flat plate material 51 having a diameter of 1A is punched and formed. Next, the center part (solid line 52 in FIG. 5(B)) of the flat plate material 51 is squeezed inward (upper side in FIGS. 6(B) and 7(B)), and both side parts (see FIG. 5(B)) are squeezed. (B) Solid line 53.5
3) Squeeze it outward (lower side in Figures 6(B) and 7(B)). Then, the whole is shown in Figures 5 (C) and 6 (
As shown in FIG. 5(D), FIG. 6(D), and FIG. 7(D),
After squeezing it until it has a circular cross section, the joint part 54 is joined by seam welding or the like, and the hydraulic shock absorber 5 is assembled.
An outer cylinder 20 is formed. (Thus, according to the double cylinder hydraulic shock absorber 5 of this embodiment,
Since the peripheral wall of the outer cylinder 20 is made to protrude outward in the radial direction to form the lower spring receiver protrusion 2OA, there is no need to remove the lower spring receiver 7 in the prior art and make it 1 inch wider, improving work efficiency. In addition to reducing costs, it is possible to reliably prevent problems caused by uneven installation work during the stroke, as in the case of the lower spring receiver 7 of the prior art. In addition, since the lower spring receiving protrusion 2OA is integrally molded with the cylindrical body that becomes the outer cylinder 20, due to its structure, the lower spring receiving protrusion 2OA is
The OA will not fall off (excellent durability and improved safety). On the other hand, by forming the lower spring receiving protrusion 2OA, the volume of the surrounding liquid chamber 14 increases, and the hydraulic shock absorber increases by that amount. The amount of hydraulic oil in the container 5 can be increased, and the rate of temperature rise can be suppressed by the increased amount of oil.Furthermore, the lower spring receiving protrusion 2OA of the surrounding liquid chamber 14 serves as a radiation fin. The cooling efficiency of the hydraulic oil improves, and the temperature rise of the hydraulic oil can be actively suppressed.This makes it possible to reliably suppress the decrease in viscosity due to the temperature rise of the hydraulic oil. Hydraulic shock absorber 5
damping force characteristics can be maintained in excellent condition. As a result of the above, the reliability of the double-tube hydraulic shock absorber 5 can be significantly improved. In this embodiment, the lower spring receiving protrusion 2OA is formed by protruding the circumferential wall of the outer cylinder 20 outward in the radial direction in an annular shape. The lower spring receiving protrusion 20 may be formed by forming a plurality of protrusions in the shape or around the outer cylinder 20. [Effects of the Invention] As detailed above, according to the present invention, the lower spring receiving protrusion is formed by protruding radially outward from the peripheral wall of the outer cylinder, so that the work for attaching the lower spring receiving protrusion is not necessary. The process becomes unnecessary and costs can be reduced. Furthermore, since the lower spring receiver protrusion is integrally formed with the outer cylinder, the lower spring receiver will not fall off (it has excellent durability and heat dissipation, and improves safety and reliability).

[Brief explanation of the drawing]

Figure 1 is a side view showing the double-tube hydraulic shock absorber of the present invention, and Figures 2 (A) and (B) are Vertical cross-sectional views showing different processes when the molding method is applied, FIGS. 3(A) and 3(B),
(C) is a vertical cross-sectional view showing the different processes when applying the squeeze forming method to form the outer cylinder of the double-tube hydraulic shock absorber shown in Figure 1; FIGS. 5(A) and 5(B) are perspective views showing the molding state when the split press method is applied to mold the outer cylinder of the cylindrical hydraulic shock absorber;
(C) and (D) are front views showing different processes when applying the non-divided press working method, and Fig. 6 (A) and (B)
), (C). (D) is Fig. 5 (A), (B), and (C), respectively. (D) (7) VIA-VIA, VIB-VIB,
VIC-VIG. 7th cross-sectional view seen from the arrow direction of VI D - MI D
Figures (A), (B), (C), and (D) are respectively shown in Figure 5 (
A), (B), (C), (D) ■A-■A. ■B-■B, ■C-■C1 ■D-■A sectional view seen from the arrow direction of Figure 9 is the first
FIG. 10 is a partially broken sectional view showing a conventional example, FIG. 10 is a sectional view showing a second conventional example, and FIG. 11 is a sectional view showing a third conventional example. 5... Double cylinder hydraulic shock absorber, 9... Coil spring as a suspension spring, 11... Inner cylinder, 12... Piston, 13... Piston rod, 20... Outer cylinder ,
2OA...Lower spring receiving protrusion.

Claims (1)

[Claims] an outer cylinder, an inner cylinder provided within the outer cylinder, a piston slidably provided within the inner cylinder, and a piston rod having one end fixed to the piston and the other end extending from the outer cylinder. A double-tube hydraulic shock absorber comprising: a spring receiving protrusion that projects radially outward and serves as a spring receiver for a suspension spring; and a spring receiving projection is integrally formed on the peripheral wall of the outer cylinder. Double cylinder hydraulic shock absorber.