Suspension system

Abstract: A suspension system includes a shock absorber (1), a coil spring (8), a tubular dust cover (3), and an insulator (7). The shock absorber is provided with a first seat and a second seat at the opposite ends. The insulator (7) is disposed between the first seat and the coil spring, and includes a body for holding the coil spring, and a contact projecting from the body in a centripetal direction and having a portion (76) being brought into contact with one of the opposite ends of the dust cover. The insulator forms a space between the first seat and an outer portion with respect to the portion of the contact. Thus, the insulator reduces the wear of the first seat resulting from the contact with the dust cover, inhibits the first seat from corroding, and keeps the strength of the first seat from decreasing.

Description: The present invention relates to a suspension system which is applicable to automobiles. A suspension system has been interposed between a wheel and an automobile body in order to damp vibrations which are transmitted from the wheel to the automobile body. As illustrated in Fig. 4, such a suspension has been known to comprise a shock absorber 11, a coil spring 18, and a tubular dust cover 13. The shock absorber 11 includes a tubular member 11a, and a piston rod 11b. The tubular member 11a is connected to a wheel. The piston rod 11b is disposed so as to advance and retract with respect to the tubular member 11a, and is connected to an automobile body. The coil spring 18 is disposed outside the shock absorber 11 by a predetermined space, and has opposite ends. One of the opposite ends of the coil spring 18 is held on a first seat 16, which is installed to the tubular member 11a, by way of an insulator 17. Another one of the opposite ends of the coil spring 18 is held on a second seat 15, which is installed to the piston rod 11b. The dust cover 13 is disposed between the shock absorber 11 and the coil spring 18, and has opposite ends. One of the opposite ends of the dust cover 13 is held by the piston rod 11b. The piston rod 11b is held sildably on the tubular member 11a. In order to reliably protect the upper-end sealing portion of the tubular member 11a, the dust cover 13 accordingly tends to be longer in the downward direction. As a result, the lower end of the dust cover 13 is placed in proximity with the first seat 16, and consequently contacts with the first seat 16 with an increasing frequency when bounding occurs. The first seat 16 is usually made from metal, and is subjected to a cationic painting, etc, for ensuring an adequate rust-proof on the surface. However, the cationic paint film is worn out by being repeatedly brought into contact with the dust cover 13. As a result, the first seat 16 is corroded, or its metallic substrate is come off to decrease the strength. Japanese Unexamined Utility Model Publication (KOKAI) No. 60-173,406 discloses a technique for coping with the problem. According to the publication, the dust cover 13 is provided with a projection at the lower end, thereby decreasing the contacting area between the dust cover 13 and the first seat 16. However, if projection is formed at the lower end of the dust cover 13 as disclosed in the publication, the entire load of the dust cover 13 is transmitted as a whole to the first seat 16 by way of the projection when the dust cover 13 contacts with the first seat 16. As a result, the first seat 16 is subjected to a concentrated load at the contact with the projection, and may possibly be worn out quickly. Furthermore, EP-A-0 407 360 showing all of the features of the preamble of claim 1 describes a suspension system, in which a tubular bellows member 16 is interposed between one end of a helical spring and the inner face of a corresponding supporting plate 9, 15 at the tubular member. The present invention has been developed in view of the aforementioned problems. It is therefore an object of the present invention to provide a suspension system which enables to reduce the wear of a first seat resulting from the contact with a dust cover, to inhibit it from corroding, and to keep its strength from decreasing. A suspension system according to the present invention carries out the object, and comprises by having the characterizing features defined in claim 1. Thus, the insulator reduces the wear of the first seat resulting from the contact with the dust cover, inhibits the first seat from corroding, and keeps the strength of the first seat from decreasing. In a modified version of the present suspension system, the contact is free from contacting with the first seat when it is kept from contacting with another one of the opposite ends of the dust cover. In the present suspension system, the shock absorber contracts against the urging force of the coil spring when bounding occurs. The dust cover descends together with the piston rod, and contacts with the contact of the insulator at the lower end. At this moment, when the contact itself is rigid, the contact receives the load of the dust cover. Thus, the load is little transmitted to the first seat. Moreover, when the contact is somewhat rigid, the contact flexes. Accordingly, the load is relieved, and the relieved load is transmitted to the first seat. As a result, the load of the dust cover is hardly transmitted to the first seat as it is. Therefore, it is possible to reduce the wear of the first seat, to inhibit the first seat from corroding, and to keep the strength of the first seat from decreasing. Further, when the contact and another one of the opposite ends of the dust cover are brought into contact with each other, the insulator forms a space between the first seat and an outer portion with respect to the portion of the contact, portion which is brought into contact with another one of the opposite ends of the dust cover. As a result, the contact contacts with the surface of the first seat over a reduced area, and foreign materials, such as water, etc., are less likely to reside between the contact and the first seat. Hence, it is possible to securely inhibit the first seat from corroding. Furthermore, in the modified version of the present suspension system, when the contact is free from contacting with another one of the opposite ends of the dust cover, the contact is kept from contacting with the first seat. Therefore, in the modified version, it is possible to further relieve the load being transmitted from the dust cover to the first seat by way of the contact, and to further securely inhibit the first seat from corroding. In accordance with the present suspension system, the insulator includes the body for holding the coil spring, and the contact. The contact projects from the body in a centripetal direction, and has the portion being brought into contact with another one of the opposite ends of the dust cover. When the contact and another one of the opposite ends of the dust cover are brought into contact with each other, the insulator forms the space between the first seat and an outer portion with respect to the portion of the contact, portion which is brought into contact with another one of the opposite ends of the dust cover. The thus constructed insulator enables to reduce the wear of the first seat resulting from the contact with the dust cover, to inhibit the first seat from corroding, and to keep the strength of the first seat from decreasing. Moreover, in the modified version of the present suspension system, when the contact is kept from contacting with another one of the opposite ends of the dust cover, the contact is free from contacting with the first seat. The thus constructed contact enables to further relieve the load being transmitted from the dust cover to the first seat by way of the contact, and to further securely inhibit the first seat from corroding. A more complete appreciation of the present invention and many of its advantages will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings and detailed specification, all of which forms a part of the disclosure: Fig. 1 is a cross-sectional view of a Preferred Embodiment of a suspension system according to the present invention; Fig. 2 is a plan view of an insulator in the Preferred Embodiment of the present suspension system; Fig. 3 is a cross-sectional view taken along line "3"-"3" of Fig. 2; Fig. 4 is a cross-sectional view of the conventional suspension system; and Fig. 5 is a modified version of the insulator in the Preferred Embodiment of the present suspension system. Having generally described the present invention, a further understanding can be obtained by reference to the specific preferred embodiments which are provided herein for the purpose of illustration only and not intended to limit the scope of the appended claims. Fig. 1 illustrates a cross-sectional view of a Preferred Embodiment of the present suspension system. Fig. 2 illustrates a plan view of an insulator in the Preferred Embodiment. Fig. 3 illustrates a cross-sectional view taken along line "3"-"3" of Fig. 2. As illustrated in Fig. 1, the Preferred Embodiment of the present suspension system is provided with a shock absorber 1. The shock absorber 1 includes a tubular member la, and a piston rod 1b. The tubular member la is connected with a wheel. The piston rod 1b is connected with a vehicle body operably so as to advance and retract with respect to the tubular member la. The piston rod 1b has opposite ends, and is provided with a rubber stopper 2 and a holder fitting 4 at the leading end. The rubber stopper 2 inhibits the piston rod 1b from excessively displacing downward. The holder fitting 4 holds a dust cover 3 which covers around the piston rod 1b. The holder fitting 4 is formed as a cylindrical shape having opposite ends. The lower end of the holder fitting 4 is opened, and the upper end thereof is opened so as to form an installation hole by its inner peripheral surface. Into the installation hole, the piston rod 1b is fitted at the upper leading end which is provided with a male-threaded portion, and which is fastened to the holder fitting 4 by a nut 1c. The rubber stopper 2 is formed virtually as a cylindrical shape having bellows. When the rubber stopper 2 is disposed on the outer periphery of the piston rod 1b, it is fastened to the upper-end inner peripheral surface of the holder fitting 4 at the upper end. The dust cover 3 is formed substantially as a cylindrical shape having bellows, and has a diameter slightly larger than that of the tubular member la of the shock absorber 1. The dust cover 3 is fastened to an outer periphery of the holder fitting 4 at the upper end. The male-threaded upper end of the piston rod 1b is provided with an upper seat or so called second seat 5 (i.e., the second seat) which is disposed so as to superimpose on the upper end of the holder fitting 4. The upper seat 5 includes a cylinder-shaped installation fitting 5a, a ring-shaped reinforcement fitting 5b, and a ring-shaped rubber block 5c. The reinforcement fitting 5b is disposed outside the installation fitting 5a coaxially therewith. The rubber block 5c is bonded integrally with the installation fitting 5a and the reinforcement fitting 5b by vulcanization, and is formed virtually as a disk In addition, the rubber block 5c is provided with a ring-shaped seat surface 5d on the lower surface. A lower seat or so called first 6 (i.e., the first seat) is fastened by welding to a lower outer peripheral surface of the tubular member la of the shock absorber 1. The lower seat 6 is made from metal, and is formed substantially as a dish shape having a central hole. The shock absorber 1 is fitted into the central hole of the lower seat 6, and fastened thereto by welding. A coil spring 8 having upper and lower ends is interposed between the lower seat 6 and upper seat 5. The coil spring 8 is held by the lower seat 6 at the lower end by way of an insulator 7, and is held by the seat surface 5d of the upper seat 5. As illustrated in Fig. 2, the insulator 7 includes a ring-shaped body 7a, and three contacts 7b. The body 7a holds the coil spring 8. As shown in Fig. 2, the contacts 7b project from an inner peripheral surface of the body 7a in a centripetal direction, and are spaced equally by a predetermined angle in a circumferential direction. As can be appreciated from Fig. 1, the contacts 7b project up to a position where their leading end goes slightly beyond the lower-end inner peripheral surface of the dust cover 3. Accordingly, the leading end of the contacts 7b can contact with the lower end of the descending dust cover 3. Moreover, as illustrated in Figs. 1 and 3, the contacts 7b are provided with a projection 7c on their lower surface of their leading end. The projection 7c forms a space 7d between the lower surface of the contacts 7b and the upper surface of the lower seat 6 when the lower end of the dust cover 3 contacts with the contacts 7b. For instance, Fig. 1 illustrates a situation, in which the piston rod 1b moves downward, and thereby the dust cover 3 descends to contact with the contacts 7b. Note that, when the lower end of the dust cover 3 can contact with the contacts 7b so as to produce a space between the lower surface of the contacts 7b and the upper surface of the lower seat 6, it is unnecessary to provide the projections 7c for the insulator 7. The thus constructed Preferred Embodiment of the present suspension system is connected to a wheel at the tubular member la of the shock absorber 1, and is connected to a vehicle body at the leading end of the piston rod 1b by way of the holder fitting 4 and the upper seat 5. When bounding occurs, the piston rod 1b contracts downward against the urging force of the coil spring 8. The dust cover 3 descends together with the piston rod 1b, and contacts with the contacts 7b of the insulator 7 at the lower end. Accordingly, the load of the dust cover 3 is transmitted to the lower seat 6 by way of the contacts 7b which are flexed by elastic deformation. As a result, the load of the dust cover 3 is hardly transmitted to the lower seat 6 as it is. Hence, the lower seat 6 is worn less, is inhibited from corroding, and its strength is kept from decreasing. There is formed the space 7d between the lower surface of the contacts 7b and the upper surface of the lower seat 6 by the projections 7b which are provided on the lower surface of the contacts 7b. Thus, the contacts 7b and the lower seat 6 contact with each other with a reduced contact area. Therefore, the foreign materials, such as water, are less likely to reside at the contact. As having been described so far, the Preferred Embodiment of the present suspension system includes the insulator 7 which is provided with the contacts 7b. The contacts 7b project from the body 7a of the insulator 7 in a centripetal direction, and are disposed so as to be present at positions where they contact with the lower end of the descending dust cover 3. Thus, the insulator 7 enables to reduce the wear of the lower seat 6 resulting from the contact with the dust cover 3, to inhibit the lower seat 6 from corroding, and to keep the strength of the lower seat 6 from decreasing. In addition, the contacts 7b of the insulator 7 are provided with the projection 7c on their lower surface. The projections 7c form the space 7d between the lower surface of the contacts 7b and the upper surface of the lower seat 6. Thus, the contacts 7b contact with the upper surface of the lower seat 6 with a reduced area, and accordingly the foreign materials, such as water, are less likely to reside therebetween. As a result, the insulator 7 can inhibit the lower seat 6 from corroding further reliably. Instead of providing the projection 7c on the lower surface of the contacts 7b, or in addition to the provision, the contacts 7b can be made from materials which have such rigidity that frees the contacts 7b from contacting with the lower seat 6 when the contacts 7b are kept from contacting with the lower end of the dust cover 3. With this arrangement, the insulator 7 can effect the advantages similarly to the provision of the projections 7c, or can produce a further shock-relieving effect. In the present suspension system, the insulator 7 can be provided with the contacts 7b in a quantity of three at least when the contacts 7b are spaced equally by a predetermined angle in a circumferential direction. Note that the insulator 7 can be provided with three or more of the contacts 7b. Moreover, a single ring-shaped portion of a contact can substitute for the portion of the contacts 7b. For instance, the single ring-shaped portion of the contact covers all the area, with which the lower end of the descending dust cover 3 contacts, in a circumferential direction as illustrated in Fig. 5. Having now fully described the present invention, it will be apparent to one of ordinary skill in the art that many changes and modifications can be made thereto without departing from the spirit or scope of the present invention as set forth herein including the appended claims.

Claims: Suspension system, comprising a shock absorber (1) including a tubular member (1a), a piston rod (1b) disposed so as to advance and retract in the tubular member (1a), a first seat (6) installed to the tubular member (1a), and a second seat (5) installed to the piston rod (1b); a coil spring (8) disposed outside said shock absorber (1) by predetermined space, and having opposite ends, one of the opposite ends held on the first seat (6) by way of an insulator (7), another one of the opposite ends held on the second seat (5); and a tubular dust cover (3) having opposite ends, and disposed between said shock absorber (1) and said coil spring (8), one of the opposite ends held by the piston rod (1b); said insulator (7) including a body (7a) for holding said coil spring (8), characterised in that said insulator (7) includes an axially elastically flexible contact portion (7b) projecting from said body (7a) in a centripetal direction such that it can be brought into contact with the other one of said opposite ends of said dust cover (3) due to relative movement of said piston rod (1b) and said tubular member (1a), opposite the dust cover (3) said contact portion (7b) forming an axial space (7d) between said first seat (6) and said contact portion (7b) to allow axial displacement of the latter (7b) due to its flexibility such that it is brought in contact with said first seat (6) against the force applied by said other one of said opposite ends of said dust cover (3). Suspension system according to claim 1, wherein said contact portion (7b) is free from contacting with said first seat (6) when it is kept from contacting with said other one of the opposite ends of said dust cover (3). Suspension system according to claim 1, wherein said contact portion (7b) is provided with a projection (7c) on its lower surface, wherein said projection (7c) is brought into contact with an upper surface of said first seat (6). Suspension system according to claim 1, wherein said contact portion (7b) is such firm that it is free from contacting with said first seat (6) when it is kept from contacting with said other one of the opposite ends of said dust cover (3). Suspension system according to claim 1, wherein said insulator (7) is provided with said contact portions (7b), which are spaced equally by a predetermined angle in a circumferential direction, in a quantity of three at least. Suspension system according to claim 1, wherein said portion of said contact portion (7b) is formed as a single ring-shaped portion.

Inventors: HAYASHI NAOKI, KOBA HIROYUKI, TSUKAMOTO YOSHIKAZU, HAYASHI, NAOKI, KOBA, HIROYUKI, TSUKAMOTO, YOSHIKAZU
Applicants: TOKAI RUBBER IND LTD, TOYOTA MOTOR CO LTD, TOKAI RUBBER INDUSTRIES, LTD., TOYOTA JIDOSHA KABUSHIKI KAISHA
Application year: 1996
Main classification: F16F9
IPC codes: B60G11, F16F9, B60G15