Coil spring mounting structure for suspension strut

[0001] 1. Field of the Invention

[0002] The present invention relates to a suspension strut for a car in which a coil spring is integrated and assembled with a shock-absorber.

[0003] 2. Background of the Related Art

[0004] FIG. 1 is a perspective view showing a conventional car suspension strut (laid-opened Utility Model publication No. 2000-16340).

[0005] As shown in FIG. 1, a car suspension strut 100 consists of a shock-absorber 110 for generating a damping force by reciprocating a valve in the interior of the shock-absorber within which oil is filled, and a coil spring 140 located in the outside of the shock-absorber 110 in order to restore a compressed shock-absorber to the former state.

[0006] The shock-absorber 110 consists of an external case 111 for receiving the valve (not shown) and a rod 120 connected to the valve (not shown).

[0007] To connect a knuckle and a strut, a knuckle bracket 112 is mounted on the external case 111. A lower spring seat 150 is fixed to the external case 111 upper the knuckle bracket 112. According to the fixed location of the strut, instead of the knuckle bracket 112, a cylindrical shape of bracket may be mounted on the lower portion of the external case 111.

[0008] A lower spring pad 152 consisting of rubber material is rested upper the lower spring seat 150 and a coil spring 140 is mounted upper the lower spring pad 152.

[0009] Also, an upper spring pad 162 is mounted upper the coil spring 140 and then an upper spring seat 160 is inserted to the rod 120 of the shock-absorber 110.

[0010] An insulator 130 is mounted on the upper spring seat 160 in such a manner that the upper spring seat 160 and the insulator 130 are fixed to the rod 120 of the shock-absorber through a nut 125. In case of the strut installed in the front of a car, a bearing (not shown) may be installed in the inside of the insulator 130 so that the strut is rotated to a car body upon steering.

[0011] A bolt 132 mounted on the insulator 130 is a member for fixing the strut 100 to the car body.

[0012] That is, the conventional suspension strut for the car has adopted a structure in which the lower spring seat 150 is fixed to the external case 111 of the shock-absorber through a welding and then the coil spring 140 is installed in the lower spring seat 150. Accordingly, a portion (hereinafter, referring to a left winding part) at which the coil spring 140 is contacted to the lower spring seat 150 is necessary.

[0013] The left winding part is commonly set to 0.75 turns on the basis of a winding turns number of the coil spring 140. In the case that a lower spring pad 152 is installed between the coil spring 140 and the lower spring seat 150, the left winding part is likewise installed in the coil spring 140.

[0014] Likewise, the coil spring 140 mounted on the conventional car suspension strut has such a structure in which the left winding part contacted with the upper spring seat 160 is installed in the coil spring.

[0015] In the above-described conventional art, there was a problem in that the setting of the left winding part having 0.75 turns length is required and a material cost of the coil spring is high as the left winding part does not have the spring function.

[0016] Further, to avoid that the coil located at the region neighboring the left winding part is contacted with the spring seat to generate a stress concentration in the case that the coil spring is subject to an overload, a lower spring pad or an upper spring pad may be adopted. However, there was also a problem in that the spring pad for receiving the left winding part of the coil spring is enlarged in size, thereby increasing a manufacturing cost.

[0017] An object of the invention is to solve at least the above problems and/or disadvantages and to provide at least the advantages described hereinafter.

[0018] Accordingly, one object of the present invention is to solve the foregoing problems by providing a coil spring mounting structure of a suspension strut for minimizing a left winding part of a coil spring, reducing a material cost of the coil spring and simplifying a structure of a bush mounted between the coil spring and the shock-absorber.

[0019] To achieve the above object, a coil spring mounting structure for a suspension strut of the present invention comprises a spring bracket fixed to a shock-absorber and having a coupling hole; a coil spring inserted to the coupling hole, having screw threads formed on an end thereof, and nuts screw-coupled with the screw threads for fixing the coil spring to the spring bracket.

[0020] Also, the coil spring mounting structure for the suspension strut of the present invention further comprises a second bracket fixed to the shock-absorber; a clamp located on the surface of the second bracket; bolts and nuts for fixing the second bracket and the clamp; and a bush inserted between the clamp and the coil spring, having a through hole.

[0021] The invention will be described in detail with reference to the following drawings in which like reference numerals refer to like elements wherein:

[0022] FIG. 1 is a perspective view showing a conventional strut;

[0023] FIG. 2 is a perspective view showing a mounting structure of a coil spring in accordance with the present invention;

[0024] FIG. 3 is a sectional view taken along line A-A of FIG. 2;

[0025] FIG. 4 is a sectional view taken along line B-B of FIG. 2; and

[0026] FIG. 5 is a perspective view of a bush.

[0027] Now, a preferred embodiment of the present invention will be described in reference with the accompanying FIGS. 2 to 5. Same elements as those used in the conventional art are not omitted in the figures.

[0028] Referring to FIG. 2, a spring bracket 220 and a second bracket 210 are fixed to an external case 111 of a shock-absorber 110 through a welding.

[0029] A coupling hole for receiving a screw thread 141 of a coil spring (will be described hereinafter) 140 is formed in the spring bracket 220.

[0030] The screw thread 141 is formed at one end of the coil spring 140.

[0031] The screw thread portion 141 formed on the coil spring 140 is inserted into the coupling hole of the spring bracket 220 and then fixes the coil spring 140 and the spring bracket 220 through a nut 230.

[0032] A second bracket 210 neighboring the spring bracket 220 is fixed to the shock-absorber 110. The second bracket 210 has a U shape of section. Preferably, the second bracket 210 is mounted so that the longitudinal direction thereof is same with the longitudinal direction of the shock-absorber.

[0033] A clamp 300 is located on the surface of the second bracket 210, and the clamp 300 and the second bracket 210 are fixed by a bolt 310 and a nut 330.

[0034] A bush 400 is inserted between the coil spring 140 and the clamp 300.

[0035] As shown in FIG. 5, the bush 400 has projection jaws 410 formed on both side ends of a main body in which a through hole is formed. A slit 420 is formed between the through hole and a bottom.

[0036] The second bracket 210 and the spring bracket 220 of the present invention may be formed in the external case 111 of the shock-absorber and also may be formed in the rod 120 located upper the strut. That is, the brackets can be applied to a lower mounting structure as well as an upper mounting structure of the coil spring of the present invention.

[0037] As the remaining structures of the car suspension strut of the present invention excepting for the above-described parts in reference with FIGS. 1 to 5 are same with those of the conventional art shown in FIG. 1, the description for parts such as a knuckle bracket, an insulator 130, etc., is omitted.

[0038] Now, an operation of the present invention will be described.

[0039] Firstly, the nut 230 is screw-coupled with the screw portion 141 formed on the end of the coil spring 140, and the remaining portion of the screw portion 141 is inserted into the coupling hole of the spring bracket 220. Another nut 230 is screw-coupled with the end of the coil spring 140. The nut 230 is tightened with a defined coupling torque to fix the coil spring 140 to the spring bracket 220.

[0040] Because the coil spring 140 is fixed to the spring bracket 220 by the nuts 230 and 230, it is not required that the 0.75 turns of left winding part are formed as in the conventional art. That is, most of coils excepting for the screw portion 141 of the coil spring 140 act with effective turns number.

[0041] In case of controlling a location at which the coil spring 140 is mounted on the spring bracket 220 by tightening the nuts 230 and 230, the effective turns number of the coil spring 140 is changed and accordingly a spring coefficient is also changed. That is, because the spring coefficient is changed when the locations of the nuts 230 and 230 screw-coupled on the coil spring 140 are changed, it is possible that a characteristic device of the coil spring 140 are tuned finely.

[0042] The coil spring 140 fixed to the shock-absorber may be mounted through the bush 400. That is, after widening the slit 420 formed in the bush 400, the coil spring 140 is inserted into the slit and then the clamp 300 is covered thereon. The clamp 300 and the second bracket 210 formed in the shock-absorber are fixed through the bolts 310 and the nuts 330. The projection jaws 410 formed in the bush 400 act to prevent the bush 400 from being separated from the clamp 300.

[0043] Because the bush 400 is made of rubber material, when the load applied to the coil spring 140 is transferred to the shock-absorber, the bush performs a vibration-proof function.

[0044] As the present invention adopts a structure in which a screw is formed on an end of a coil spring and the screw is fixed to a spring bracket through nuts, a material loss due to the existing of the left winding part as in the conventional art does not occur. That is, because the portion which does not act as an effective turns number in the portion at which the coil spring and the spring bracket are coupled to each other, is minimized, the coil spring are decreased in material cost and weight by those of the left winding part corresponding to the 0.75 turns number.

[0045] Also, in accordance with the present invention, because the location of the portion at which the end of the coil spring and the spring bracket are coupled is controlled by the nuts, it is possible that the spring coefficient of the coil spring is controlled finely.

[0046] Also, because the present invention adopts the structure in which the coil spring is fixed to the shock-absorber using the clamp and bush, a large lower spring pad or a large upper spring pad as in the conventional art is not required thereby reducing a material cost.

[0047] Further, in accordance with the present invention, the projection jaws and the slit are formed in the bush, thereby facilitating an assembly of the bush and preventing the bush from being separated from the clamp.

[0048] While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.