MOUNTING DEVICE AND PROCESS FOR MANUFACTURE THEREOF

Abstract: A mounting device includes an outer cylinder, an inner cylinder, and an elastic insulator part positioned between said outer cylinder and inner cylinder to connect the outer cylinder and inner cylinder. The outer cylinder is made of a resin and includes a first outer cylinder molded into an annular form having at least one opening therein, and a second outer cylinder molded on the outer circumference of the first outer cylinder and covering the opening in the first outer cylinder.

Description: TITLE MOUNTING DEVICE AND PROCESS FOR MANUFACTURE THEREOF BACKGROUND OF THE INVENTION 1. Field of The Invention The present invention relates to a mounting device which supports and secures an engine, a transmission, a suspension, or the like, to the body of a vehicle, at the same time damping out engine- or suspension-generated vibrations, as well as a process for the manufacture thereof. 2. Description ofthe Related Art Mounting devices which support and secure an engine, a transmission, a suspension, or the like, to the body of a vehicle which have been long used previously have comprised rubber and like insulators held between a large and small metal cylinder. However, to reduce the weight of an automobile and also to reduce cost, the use of a resin has been attempted so as to replace the metal in the outer cylinder with a resin. Such a mounting device having an insulator placed between such a resin outer cylinder is manufactured by molding the insulator part from rubber and then injection molding a resin using the insulator part and the metal inner cylinder as the insert. However, the conventional manufacturing process has faced problems in that injection molding using rubber which is a very elastic material, if carried out under high pressure, deformed the insulator part while molding even under a relatively low pressure not only providing molded articles with poor appearance, but also leading to a failure to obtain the mechanical properties with a resin. Molding a resin insert has also faced problems in that for manufacturing a metal cylinder as an outer cylinder, the insulator part is subjected to sufficient compression behavior to increase its strength by annularly tensioning drawing the metal. But molding an insert from a resin requires providing the insulator part with compression behavior based only on the resin-characteristic shrinkage so that a molded article or an outer cylinder obtained by using a special insulator material had to become a very thick-walled molded article. It is an object of this invention to provide a mounting device which is light weight, excellent in durability and good in appearance and a process for the manufacture thereof. SUMMARY OF THE INVENTION A mounting device includes an outer cylinder, an inner cylinder, and an elastic insulator part positioned between said outer cylinder and inner cylinder to connect the outer cylinder and inner cylinder. The outer cylinder is made of a resin and includes a first outer cylinder molded into an annular form having at least one opening therein, and a second outer cylinder molded on the outer circumference ofthe first outer cylinder and covering the opening in the first outer cylinder. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a plan view showing an embodiment for the manufacturing stage of Example 1 of a mounting device of this invention. Figure 2 is a plan view showing an embodiment for the manufacturing stage of Example 2 of a mounting device of this invention. Figure 3 is a plan view showing the final embodiment of Example 1 of the mounting device of this invention. DETAILED DESCRIPTION The present invention relates to a mounting device that supports and secures an engine, a transmission, a suspension, or the like, to the body of a vehicle while at the same time damping out engine- or suspension- generated vibrations, and a process for the manufacture thereof. Specifically the invention relates to a mounting device having an insulator part placed between a resin outer cylinder and a metal or resin inner cylinder and a process for the manufacture thereof. The process for manufacturing a mounting device by other embodiments of this invention is characterized in that in a process for manufacturing a mounting device comprising an outer cylinder, an inner cylinder, an insulator part which is located between said outer cylinder and inner cylinder, and having an outer annular part which is contact with an inner circumferential face of said outer cylinder, an inner annular part in contact with an outer circumferential surface of said inner cylinder, an insulator part having at least one connector for connecting said outer annular part and said inner annular part, the process of manufacturing the mounting device comprises Step 1 of molding, using said inner cylinder as an insert, the insulator part which has at least one opening in said outer annular part; Step 2 of molding, using the molded above insulator part and the inner cylinder as the insert, a first outer cylinder which has an opening at a position corresponding to the opening; and Step 3 of molding, wherein the opening ofthe said first outer cylinder and the opening ofthe outer annular part of said insulator part are closed, using said first outer cylinder, insulator part, and inner cylinder as the insert, a second outer cylinder from a resin at least on an outer circumference of said first outer cylinder. The manufacturing process of a mounting device by other further embodiments of this invention is characterized in that in the process for manufacture of a mounting device comprising an outer cylinder, an cylinder, an insulator part which is located between said outer cylinder and inner cylinder, and having an outer annular part which is contact with an inner circumferential face of said outer cylinder, an inner annular part in contact with an outer circumferential surface of said inner cylinder, an insulator part having at least one connector for connecting said outer annular part and said inner annular part, the process of manufacturing the mounting device which comprises Step 1 of molding a first outer cylinder having at least one opening from a resin; Step 2 of molding, using said molded first outer cylinder and the the inner cylinder as the insert, an insulator part having an outer annular part with an opening at a position corresponding to the opening provided on the first outer cylinder; and Step 3 of molding, wherein the opening of the said first outer cylinder and the opening ofthe outer annular part of said insulator part are closed, using said first outer cylinder, insulator part, and inner cylinder as the insert, a second outer cylinder from a resin at least on an outer circumference of said first outer cylinder. The mounting device manufacture by this invention comprises molding the outer cylinder separately into a first outer cylinder and a second outer cylinder so as to have it provided with excellent strength and good appearance. A thin walled first outer cylinder is molded under relatively low pressure, and an insulator part is preconnected to the first outer cylinder to secure the insulator part, which allows molding the second outer cylinder under high pressure, resulting in a mounting device with good appearance. Since the openings provided on the first outer cylinder, the outer annular section ofthe insulator are closed off when the second outer cylinder is molded, compression behavior can be applied to the insulator part without depending on the resin-inherent shrinkage alone, so as to permit manufacturing a high strength mounting device. This construction does not require the outer cylinder to be thicker walled than necessary. Since a resin is used instead of metal, the device is light weight and uses an outer cylinder which is not thick walled to make it even lighter weight than the conventional mounting devices made of a resin. Preferred embodiments for this invention are described in detail by referring to the examples described in the attached drawings. These examples are used to explain this invention and in no way do they limit the scope of this invention. EXAMPLES Examples of this invention are described by referring to Figures 1-3. In the figures, 10 is an outer cylinder comprising a first outer cylinder 11 and a second outer cylinder 12 and is molded from a glass fiber reinforced thermoplastic resin. Preferred thermoplastic resins which meet the heat resistance and strength requirements are polyamides, polyesters, or polyphthalamides, and the like. 20 is a metal inner cylinder which can be obtained by machi-ning a steel pipe. The inner cylinder 20 may be an article molded from a resin, such as a polyamide, if excellent sliding properties and high strength are assured. 30 is an insulator part which is molded from a natural rubber, a synthetic rubber, or the like elastomer, preferably molded from a blended rubber based on natural rubber with a diene rubber, such as styrene butadiene rubber, butadiene rubber, and the like, because they are outstanding in vibration isolation, preferably one molded from an ethylene-propylene-diene terpolymer (EPDM rubber) owing to outstanding heat resistance, as well as one molded from a chloroprene rubber owing to its combination of excellent vibration isolation and heat resistance. ICBMIUM The insulator part 30 comprises an outer annular part 31 which is bound to the inner circumferential face of the first outer cylinder 11 of outer cylinder 10, inner annular part 33 bound to the outer circumferential face of inner cylinder 20, link 32 which links the outer annular part 31 to the inner annular part 33. There should be one or more links 32 and their shape, size, and position are arbitrary within the range of not causing any problems in strength as illustrated in Figure 1 or Figure 2 with no particular limitation. Openings 34 and 14 are provided, respectively, on the outer annular part 31 and the first cylinder 11 without any restrictions as to the their numbers and positions, which may be provided at symmetrical positions 180 degrees apart from each other as given in Figure 1 or may be at a single position as shown in Figure 2. Openings are preferably provided as given in Figure 1 or Figure 2 considering the ease of molding and assembling and the strength limitations. In Example 1, for the process for manufacturing a mounting device of this invention, in Step 1, insulator part 30 is molded from a rubber blend of a natural rubber base with a styrene butadiene rubber using a metal inner cylinder 20 as an insert, into a configuration as shown in Figure 1 or Figure 2 so as to have an outer annular part 31 provided with an opening 34. The molding is carried out by compression molding under conditions of a mold temperature of 145-165°C and 20-60 minutes. Molding can also be carried out by injection molding under conditions of a flow temperature of 175-185°C for 60 seconds - 15 minutes- The molding conditions vary somewhat depending on parts, shapes, gate positions, etc. If a metal inner cylinder 20 is used, the surface ofthe inner cylinder 20, that face ofthe inner cylinder 20 coming in contact with the inner annular part 33, is preferably pretreated with an adhesive, such as a phenolic adhesive or the like, so as to increase the adhesion ofthe cylinder to the insulator part 30. Next, in step 2, the insulator part 30 molded in step 1, along with the metal inner cylinder 20, are placed as an insert into a mold followed by injection molding an outer cylinder 11 having an opening 14 at a position corresponding to the opening 34 ofthe insulator part 30. Molding is carried out in this case so as to mold at the same time on the first outer cylinder 11 lugs 15 which project outward in tiie radial direction at both ends adjacent to opening(s) 14. Injection molding is carried out under conditions of injection pressure of 400-450 kgf/cm^ and a mold temperature of 100-120°C. The first outer cylinder is 2-3 mm in wall thickness. In order to increase the adhesion ofthe insulator part 30 to the first outer cylinder 11, the face which comes in contact with the outer annular part 31 of the first outer cylinder is preferably pretreated with an adhesive, such as a phenolic adhesive, or the like. In steps 1 and 2, the first outer cylinder 11 and inner cylinder 20 are linked and integrated via insulator part 30. In step 3, a second outer cylinder 12 is molded using the integrated first cylinder 11, insulator part 30, and inner cylinder 20 as an insert; the integrated first outer cylinder 11, insulator part 30, and inner cylinder 20 are placed, with the two lugs being gripped, into a mold for molding the second outer cylinder 12. This is slightly larger in size than the first outer cylinder 11 with its opening 14 closed and the insulator part 30 with its opening 34 ofthe outer annular part 31 being closed, thereby injection molding the second outer cylinder 12 by applying compression to the insulator part with openings 14 and 34 being closed. The injection molding is carried out under conditions of an injection pressure of 800-1,000 kgf/cm^ and a mold temperature of 110-120°C. The first outer cylinder is 2-3 mm in wall thickness. The resultant molded mounting device is illustrated by Figure 3. In this example, the second outer cylinder 12 is molded not only to envelop the outer circumference ofthe first outer cylinder 11 including lugs 15, but also to extend around the side face ofthe first outer cylinder 11. In terms of the viewpoint ofthe strength alone, it should be sufficient ifthe second outer cylinder 12 is at least present on the outer circumference side ofthe first outer cylinder 11. In another example, in the above first step, the first outer cylinder 11 is molded and then in the second step, insulator part 30 may be molded with the first outer cylinder 11 which has been molded and with the metal inner cylinder 20 as the insert. Step 3 is the same as the above. As described above, the present invention can provide a resin-rubber mounting device which is lighter in weight than the conventional resin-rubber mounting devices, is good in appearance, and is durable as a metal-rubber mounting device. The use ofthe manufacturing process of this invention makes it possible to mold the first outer cylinder and second outer cylinder from different resin materials, for example, using a high flow resin for the first outer cylinder, and a second cylinder may be molded from a resin with more emphasis on chemical resistance, appearance, and heat resistance.

Claims: WHAT IS CLAIMED IS: 1. A mounting device comprising an outer cylinder, an inner cylinder, and an elastic insulator part positioned between said outer cylinder and inner cylinder to connect the outer cylinder and inner cylinder, wherein the improvement comprises said outer cylinder being made of a resin and comprising a first outer cylinder molded, at a first molding, into an annular form having at least one opening therein, and a second outer cylinder molded on the outer circumference ofthe first outer cylinder, at a second molding, in which the opening in the first outer cylinder is closed. 2. A mounting device as set forth in Claim 1 wherein said first outer cylinder is provided with lugs which project outwardly in a radial direction at both ends adjacent to said opening. 3. In a process for manufacturing a mounting device comprising an outer cylinder, an inner cylinder, an insulator part which is located between said outer cylinder and inner cylinder, and having an outer annular part which is contact with the inner circumferential face of said outer cylinder, an inner annular part in contact with the outer circumferential surface of said inner cylinder, an insulator part having at least one connector for connecting said outer annular part and said inner annular part, the process of manufacturing the mounting device which comprises Step 1 of molding, using said inner cylinder as the insert, the insulator part which has at least one opening in said outer annular part; Step 2 of molding, using the above molded insulator part with the inner cylinder as an insert, a first outer cylinder which has an opening at a position corresponding to the opening; and Step 3 of molding, wherin the opening of the said first outer cylinder and the opening ofthe outer annular part of said insulator part are closed, using said first outer cylinder, insulator part, and inner cylinder as an insert, a second outer cylinder from a resin at least on the outer circumference of said first outer cylinder. 4. In the process for manufacture of a mounting device comprising an outer cylinder, an inner cylinder, an insulator part which is located between said outer cylinder and inner cylinder, and having an outer annular part which is contact with an inner circumferential face of said outer cylinder, an inner annular part in contact with an outer circumferential surface of said inner cylinder, an insulator part having at least one connector for connecting said outer annular part and said inner annular part, the process of manufacturing the mounting device which comprises Step 1 of molding a first outer cylinder having at least one opening from a resin; Step 2 of molding, using said molded first outer cylinder and the the inner cylinder as an insert, an insulator part having an outer annular part with an opening at a position corresponding to the opening provided on the first outer cylinder; and Step 3 of molding, wherin the opening ofthe said first outer cylinder and the opening ofthe outer annular part of said insulator part are closed, using said first outer cylinder, insulator part, and inner cylinder as the insert, a second outer cylinder from a resin at least on the outer circumference of said first outer cylinder.

Inventors: FUJITA SUSUMU, FUJITA, SUSUMU
Applicants: DU PONT, FUJITA SUSUMU, E.I. DU PONT DE NEMOURS AND COMPANY, FUJITA, SUSUMU
Application year: 1996
Main classification: F16F1
IPC codes: B29D31, F16F1