Coupling device

Abstract: A coupling device is disclosed which comprises an elongated plate-shaped synthetic resin-made rod body (1), a synthetic resin-made cylindrical portion (2) formed integrally at at least one end of the rod body (1), and a joint piece (3) provided inside the cylindrical portion (2) and which is to be coupled to a mating object; the rod body (1) consisting of a plate member (6) ribbed orthogonally (5), and along each longitudinal perimeter, thereof; each rib (5) being recessed in an opposite direction to the projecting direction thereof and along at least a portion of the length thereof to provide a pair of outer (5A) and inner (5B) ribs which form together a double structure (4).

Description: The present invention relates to a coupling device such as a link rod used as a suspension link for automobiles, an engine mount which couples an automobile engine and a chassis, or the like, in accordance to the preambles of claims 1 and 10. Such coupling devices are known from EP-A-0176934. Other well-known coupling devices include a link rod shown by way of example in FIGS. 1 to 3 of the accompanying drawings. As best shown in FIGS. 1 to 3, the link rod comprises an elongated plate-like rod body 100 made of a synthetic resin. The rod body 100 has a cylindrical end portion 101 formed integrally at each end thereof. Each cylindrical portion 101 has a cylindrical joint piece 102 disposed therein. A rubber-made elastic joint piece 103 is formed between the cylindrical portion 101 and joint piece 102. The rod body 100 consists of a plate member 105 ribbed as indicated with a reference numeral 104 to reinforce the plate member 105 and hence the rod body 100 as a whole. The ribs 104 are formed in two pairs, upper and lower, on the plate member 105. The ribs 104 in each pair extrude in opposite directions orthogonal to the plate member 105. They extend along the longitudinal perimeters, upper and lower, respectively, of the plate member 105 as well as between the cylindrical portions 101. If such a link rod is used as a suspension link of an automobile, the rod body 100 or any other synthetic resin-made portion thereof is likely to be broken by a stone or the like thrown from the road surface by the wheel of the running automobile or by a curb with which the rod body 100 will possibly collide when the automobile comes too close to the sidewalk. If the rod body or cylindrical end portion is cracked or damaged, the link rod itself will be damaged or loose its strength due to stress concentration at such a cracked or damaged Accordingly, the present invention has an object to overcome the above-mentioned drawbacks of the prior art by providing a coupling device of which a synthetic resin-made portion likely to collide with such a stone or other object is improved in strength. The above object can be accomplished by providing coupling devices according to claims 1 and 10. In the coupling device according to the present invention, since at least a portion of the cylindrical portion of the coupling device has a double structure, the outer rib will protect the inner one. Even if the outer rib or the perimeter is damaged by a stone or the like as mentioned above, the inner rib can be protected by the outer rib so that the strength of the coupling device can be maintened. The invention will be further described with reference to one accompanying drawings, in which: FIG. 1 is a partially fragmentary front view of a conventional coupling device; FIG. 2 is a plan view of the coupling device shown in FIG. 1; FIG. 3 is a sectional view taken along the line X-X in FIG. 2. FIG. 4 is a plan view of an embodiment of a coupling device which is not covered by one claims; FIG. 5 is a sectional view taken along the line A-A in FIG. 4; FIG. 6 is a front view of the embodiment shown in FIG. 4; FIG. 7 is a plan view of a first embodiment of a coupling device of the present invention; FIG. 8 is a sectional view taken along the line B-B in FIG. 7; FIG. 9 is a sectional view taken along the line C-C in FIG. 7; FIG. 10 is a plan view of a second embodiment of a coupling device of the present invention; FIG. 11 is a sectional view taken along the line D-D in FIG. 10; FIG. 12 is a sectional view taken along the line E-E in FIG. 10; FIG. 13 is a front view of the second embodiment shown in FIG. 10; FIG. 14 is a plan view of a third embodiment of a coupling device of the present invention; FIG. 15 is a sectional view taken along the line F-F in FIG. 14; and FIG. 16 is a front view of the third embodiment shown in FIG. 14. FIG. 4 illustrates an embodiment which is not covered by the claims. As shown, it is comprised of an elongated plate-like synthetic resin-made rod body 1, a synthetic resin-made cylindrical portion 2 formed integrally on either end of the rod body 1, a joint piece 3 disposed within the cylindrical portion 2 and which is to be connected to a mating object, and a rubber-made elastic member 4 disposed between the cylindrical portion 2 and joint piece 3. In this embodiment, the joint piece 3 is a metallic cylinder through which a bolt is penetrated. The rod body 1 is formed from a plate member 6 ribbed as indicated with a reference numeral 5 along the perimeter thereof defining the profile thereof. The ribs 5 protrude in opposite directions orthogonal to the plate member 6. That is, the rod body 1 has an "H-shaped" cross section. According to said embodiment, one of the upper and lower pairs of ribs 5 is recessed as indicated with a reference numeral 7 longitudinally thereof. Thus, the rib 5 consists of an outer rib portion 5A and inner rib portion 5B which form together a double structure. FIG. 5 is a sectional view taken along the line A-A in FIG. 4. FIG. 5 best shows the above-mentioned double structure of the rib 5. As will be seen, the rod body 1 is formed so that upper and lower halves thereof divided by a horizontal line L passing through the vertical mid point thereof are generally equal in area to each other. In this embodiment, the recess 7 is formed to extend to either cylindrical portion 2. However, the double structure of the rod body 1 may be formed to extend along an appropriate length of the rod body 1 as necessary. Also, since the outer and inner rib portions 5A and 5B in the double structure of the rod body 1 are so thin because of the recess 7 that a synthetic resin material will flow slowly during injection molding of the product, it is possible to adjust the position of a weld taking place in the molded product. When a gate 8 is located as shown, welds will take place off the upper right of the right-hand cylindrical portion 2 and off the upper left of the left-hand cylindrical portion 2, respectively. FIG. 6 is a front view, from below, of the coupling device on the assumption that FIG. 4 is a plan view. The coupling device shown in FIGS. 4 to 6 is produced by setting the joint piece 3 made of a metallic cylinder in a vulcanization injection mold, injecting and vulcanizing a rubber material about the joint piece 3, and then fitting the rubber-made elastic member 4 onto the joint piece 3. Next, two assemblies thus made of the joint piece 3 and rubber-made elastic member 4 are set in an injection mold, and a molten resin is injected from the gate 8 into a cavity defined between the two rubber-made elastic members 4 thus set while the resin is fed to around the respective rubber-made elastic members 4. In this way, the cylindrical portions 2 made of the synthetic resin are formed about the rubber-made elastic member 4, and the synthetic resin-made rod body 1 is thus molded between the cylindrical portions 2. The rubber-made elastic member 4 is compressed under the injection pressure of the molten resin. The link rod for vehicles is 10 to 100 cm long. The link rod 1 in the above-mentioned embodiment is 60 cm in total length, the width of the portion connecting the two cylindrical portions 2, namely the length along the line A-A in FIG. 4, is 40 mm, the width of the recess 7 is 3 mm, the width of each of the outer and inner ribs 5A and 5B is also 3 mm, and the width of the rib 5 in which the recess 7 is not formed is 6 mm. The width of the recess 7 is a minimum of 2 mm because of the mold's geometry. If this recess width is too large, the intended purpose cannot be attained. FIG. 7 shows the first embodiment of the present invention in which a similar recess 7,71 to the recess 7 in the previous embodiment is formed in each rib 5 in one pair of the opposite ribs 5 as well as in the other pair. According to this embodiment, a recess 72 is formed in a part of the cylindrical portion 2 as well. Thus, the part of the cylindrical portion 2 has a double structure. In this embodiment, the recesses 7,71 are formed in the ribs, except for a part thereof, which are joined to the rod body 1. FIG. 8 is a sectional view taken along the line B-B in FIG. 7. As shown, the rod body 1 is so formed that upper and lower halves thereof divided by a line L passing through the vertical mid point thereof are generally equal in area to each other. FIG. 9 is a sectional view taken along the line C-C in FIG. 7. The cylindrical portion 2 has the recesses 72 formed in an opposite direction to the projecting direction thereof and concentrically from either end thereof.. Thus, a peripheral part of the cylindrical portion 2 has a double structure. FIG. 10 is a plan view of a second embodiment in which the recess 7 is formed only in one pair of the ribs 5 to form a similar double structure to that shown in FIG. 7. Also, the recess 72 is formed in a part of the cylindrical portion 2 in a same direction as that of the recess 7 in the rod body 1 (upper rib in the plane of the drawing). Thus the cylindrical portion 2 has a double structure. In the second embodiment shown in FIGS. 10 and 11, a projection 9 is provided to position a gate therein for use during an injection molding. A gate is located in either of the two positions indicated with the reference numeral 8. Also, in this embodiment, the rod body 1 has a double structure formed only along one longitudinal perimeter thereof as seen from FIG. 11. As shown in FIG. 12, the partial double structure has the recesses 72 formed above and below the axial direction of the cylindrical portion 2. FIG. 13 is a front view of the coupling device shown in FIG. 10. In the foregoing, the present invention has been described concerning a coupling device using the joint piece 3 made of a metallic cylinder. However, it should be appreciated that a ball joint may be used in place of the cylindrical joint piece 3 as in a stabilizing link rod. In this case, the rubber-made elastic member 4 is not formed but the ball joint will be enclosed directly by the synthetic resin-made cylindrical portion 2. FIG. 14 shows the third embodiment of the present invention. This embodiment is not used as a coupling device but as a bush used in an engine mount to connect an automobile engine and a chassis as well as in various links. This coupling device comprises a cylindrical member 2 made of a synthetic resin in which a joint piece 3 is disposed. A rubber-made elastic member 4 is provided between the joint piece 3 and cylindrical member 2. The cylindrical member 2 has formed axially therein a recess 73 from both ends thereof. The recess 73 may be provided at only one end of the cylindrical member 2. Thus, the cylindrical member 2 has a double structure as shown in FIG. 15. Of this coupling device, the upper half above a horizontal line L and the lower half below the line L are generally equal in sectional area to each other. FIG. 16 is a front view of the coupling device shown in FIG. 14. This is a bottom view of the coupling device. It should be noted that a pair of fixtures 10 is formed integrally on the cylindrical member 2 for installation to any other equipment. By means of a hole 11 formed in the fixture 10, the coupling device can be fixed to any other unit than that to which the joint piece 3 is fixed. It should also be noted that the ribs 5 may be formed to provide a triple or multiple structure of the coupling device. Also, only the right or left half of each of the embodiments of the coupling device shown in FIGS. 5, 11, 12 and 15, respectively, may be formed to have a double structure. Furthermore, the outer and inner ribs 5A and 5B may be different in height from each other.

Claims: A coupling device, comprising: an elongated plate-shaped synthetic resin-made rod body (1), a synthetic resin-made cylindrical portion (2) formed integrally at at least one end of the rod body, and a joint piece (3) provided inside the cylindrical portion and which is to be coupled to a mating object; the rod body (1) including a plate member (6) having a longitudinally extending rib along each perimeter of said plate member, each of said ribs projecting in opposite directions orthogonal to the plate member; characterized in that on at least one of opposite faces of said plate member at least a portion of the length of each longitudinally extending rib comprises a pair of outer and inner ribs (5A,5B) spaced-apart from one another over said length portion with a recess (7) formed therebetween in an opposite direction to a projecting direction thereof to form together a double structure, and the cylindrical portion (2) including axial end faces of a concentric circle, at least one of said axial end faces being recessed concentrically along at least a portion of the concentric circle to thereby define two projecting regions spaced apart from one another within said portion to form together a double structure. A coupling device as claimed in claim 1, characterized in that a gate (8) for injection molding is positioned at one of the longitudinally extending ribs. A coupling device as claimed in claim 2, characterized in that a projection (9) is formed laterally of the rod body for positioning the gate (8). A coupling device as claimed in any of claims 1 to 3, characterized in that said two projecting regions are peripherally located on the axial end face corresponding to one of said opposite faces of said plate member which includes said pair of outer and inner ribs (5A,5B). A coupling device as claimed in any of claims 1 to 4, characterized in that only the longitudinally extending rib along one of the perimeters of the plate member (6) is recessed. A coupling device as claimed in claim 5, characterized in that both the inner and outer ribs (5B,5A) of the longitudinally extending rib which is recessed are smaller in thickness than the longitudinally extending rib on a remaining one of said perimeters which is not recessed. A coupling device as claimed in any of claims 1 to 4, characterized in that all portions of said longitudinally extending ribs are recessed to present inner and outer ribs (5B,5A). A coupling device as claimed in claim 7, characterized in that said rib structure further includes at least one rib in addition to, and spaced apart from, said first and second ribs (5A,5B). A coupling device as claimed in claim 8, characterized in that said first and second ribs (5A,5B) extend to different heights from said plate member. A coupling device, comprising: an elongated plate-shaped synthetic resin-made rod body (1), a synthetic resin-made cylindrical portion (2) formed integrally at at least one end of the rod body presenting axial end faces, a joint piece (3) provided inside the cylindrical portion and which is to be coupled to a mating object, and a rubber-made elastic member (4) provided between the cylindrical portion and joint piece; characterised by at least one of said axial faces of the cylindrical portion (2) being recessed concentrically along at least a portion of a concentric circle thereof to define two projecting regions spaced apart from one another within said portion to form together a double structure.

Inventors: IWASAKI KENICHIRO, IWASAKI, KENICHIRO
Applicants: BRIDGESTONE CORP, BRIDGESTONE CORPORATION
Application year: 1998
Main classification: F16C7
IPC codes: F16F1, B60G7, F16C7