Switchably-controlled, liquid sealed-type vibration isolator

Abstract: The present invention relates to a liquid sealed type vibration isolator provided in the interior thereof with a partition 10 dividing an inner chamber into a main liquid chamber 7 and two, i.e. first and second auxiliary liquid chambers 8, 9, first and second orifices 13, 14 communicating the two auxiliary liquid chambers and main liquid chamber with each other, and first and second diaphragms 4, 11 forming parts of walls of the two auxiliary liquid chambers, a movement of the second diaphragm 11 being controlled by switching the introduction into a change-over chamber 12, which is adjacent to the second diaphragm 11, of a negative pressure and atmospheric pressure from one to the other. The partition 10 is formed so that it can be assembled tentatively in the air, in which it is rendered possible to combine plural constituent parts together easily without causing the dislocation thereof to occur, minimise the relative displacement of the constituent parts ascribed to variation thereof with the lapse of time, and retain the sealability of the same parts at a high level. To attain such a structure, the partition 10 is formed of a main partition member 15 forming the first orifice 13 on an outer circumferential portion thereof and provided with the second diaphragm 11 on the portion thereof which is on the side of the main liquid chamber 7, a partition plate member 16 engaged with and fitted firmly around an outer circumference of the main partition member 15 by a caulking device and pressing a circumferential edge portion of the second diaphragm 11 to form the second auxiliary liquid chamber 9 and second orifice 14, and a partition receiving plate 17 fixed to a lower surface of the main partition member 15 by a press fitting device. This partition 10 is fitted firmly in a main metal member 1, and an outer circumferential edge portion of the partition receiving plate 17 is caulked to the main metal member 1.

Description: BACKGROUND OF THE INVENTION: FIELD OF THE INVENTION: This invention relates to a switchably controlled liquid sealed vibration isolator used to support a power unit, such as an automobile engine in a vibration isolating manner. DESCRIPTION OF THE RELATED ART: A switchably controlled liquid sealed vibration isolator adapted to switch the vibration isolating characteristics thereof in accordance with two kinds of vibrations in different frequency regions, such as shaking vibration and idling vibration has been proposed as a liquid sealed type vibration isolator which is used as a mount for supporting a vibrating body, such as an automobile engine, etc. so as not to have the vibration of the vibrating body transmitted to a body of a vehicle. For example, the closest prior art, Japanese Patent Laid-Open No. 173372/1999 proposes a switchably controlled liquid sealed type vibration isolator including a metal fixing member on the side of a vibration source, an outer cylindrical metal member on the side of a support, a vibration isolating base member interposed between the two metal members and formed of an elastic rubber member, a first diaphragm fixed to the outer cylindrical metal member so as to be opposed to the vibration isolating base member, and a partition provided between the diaphragm and vibration isolating base member, the partition and vibration isolating base member defining a main liquid chamber therebetween, the partition and first diaphragm forming therebetween a first auxiliary liquid chamber communicating with the main liquid chamber via a first orifice, the partition being provided at a main liquid chamber-side portion thereof with a second auxiliary liquid chamber communicating with the main liquid chamber via a second orifice, and an atmospheric pressure and negative pressure change-over chamber separated from the second auxiliary chamber via a second diaphragm. In this proposed liquid sealed type vibration isolator, the partition is formed of a main partition member defining the first orifice on an outer circumference thereof, and a partition plate member defining the second auxiliary chamber and orifice, the main partition member to which the second diaphragm is fixed so as to form the change-over chamber on the main liquid chamber-side portion thereof being fitted in an inner circumference of the outer cylindrical metal member, the partition plate member being fitted around the diaphragm so as to hold a circumferential edge portion thereof, both of these main partition member and partition plate member being installed so as to be held between a main liquid chamber-side surface of the vibration isolating base member and a liquid chamber-side stepped portion of the outer cylindrical metal member. However, in this partition of the above-mentioned construction, the main partition member and partition plate member have to be installed in a liquid in order by a press fitting method as orifice-communicating openings of both thereof are positioned. Therefore, the structure to be assembled becomes complicated, and, moreover, a high stability of the structure is rarely obtained due to a scatter of the accuracy of other parts. The main partition member and partition plate member are held between the vibration isolating base member and the liquid chamber-side stepped portion of the outer cylindrical metal member and thereby retained in a mere contacting state. Therefore, the predetermined functions become unable to be fulfilled due to changes with the lapse of time in the condition of the parts during the use of the vibration isolator in a vehicle-mounted state, which changes are ascribed to the fluctuation of a liquid pressure caused by the vibration of the vibration isolating base member, or permanent set in fatigue and slip of the rubber portions between the parts caused by the heat, and cause the sealability thereof to become insufficient, and the passages working as the orifices to be short-circuited. SUMMARY OF THE INVENTION: It is an object of the invention to provide a switchably controlled liquid sealed vibration isolator having a structure which permits an inner partition, by which an inner hollow space is divided into a main liquid chamber and two auxiliary liquid chambers, to be assembled tentatively in the air, plural constituent parts to be combined together reliably and easily without causing them to be dislocated, and, moreover, the relative displacement of the constituent parts which occurs due to changes with the lapse of time of themselves in a vehicle-mounted state to be reduced to a low level, whereby the retention of an excellent sealed condition among the parts and the improvement of the durability of the same parts are attained. This object is solved by the vibration isolator of claim 1. The subclaims relate to preferred embodiments of the invention. An embodiment provides a switchably controlled liquid sealed vibration isolator including a vibration isolating base member formed of an elastic rubber member, a first metal fixing member combined with one of upper and lower portions of the vibration isolating base member, a main cylindrical metal member combined with the other portion of the vibration isolating base member, a first diaphragm fixed to the main metal member so as to be opposed to the vibration isolating base member, a partition provided between the vibration isolating base member and first diaphragm, a main liquid chamber formed between the partition and vibration isolating base member, a first auxiliary liquid chamber formed between the partition and first diaphragm, a second auxiliary liquid chamber formed on a main liquid chamber-side portion of the partition, a change-over chamber separated from the second auxiliary chamber via the second diaphragm and capable of introducing thereinto an atmospheric pressure and a negative pressure in a switchable manner, and first and second orifices communicating the main liquid chamber with the first and second auxiliary chambers respectively, the vibration isolator further having the following structure: The partition has at an outer circumferential portion thereof a main partition member forming the first orifice, and the second diaphragm is provided on a main liquid chamber-side portion of the main partition member so as to form the change-over chamber in a diametrically inner portion thereof. A partition plate member pressing a circumferential portion of the second diaphragm toward the main partition member to form the second auxiliary liquid chamber between the partition plate member and the second diaphragm is engaged with and fitted firmly around an outer circumferential portion of the main partition member by a caulking device for this outer circumferential portion. A portion defined by the main partition member and partition plate member on an outer side of the second auxiliary liquid chamber is formed as the second orifice. A partition receiving plate having an outer circumferential edge portion extending outward beyond an outer end of the main partition member is fixed by a press fitting device with respect to the main partition member to the portion of the main partition member which is on the side of the first auxiliary liquid chamber. The partition plate member is fitted liquid-tightly in an inner circumferential portion of the main metal member, and the outer circumferential edge portion of the partition receiving plate is fixed with the first diaphragm to the main metal member by a caulking member. According to the liquid-sealed type vibration isolator of this construction, the structural parts of the partition incorporated in an inner portion thereof, i.e. the main partition member on an outer circumferential side of which the first orifice is formed, the second diaphragm forming the change-over chamber on the portion thereof which is on the side of the main liquid chamber, the partition plate member forming the second auxiliary chamber and orifice, and parts of the partition receiving plate can be combined together in the air temporarily with ease and separately from the main metal member without causing these members and parts to be dislocated. Therefore, after such a temporary combining operation, plural structural parts can be combined accurately by press fitting the partition plate member of the partition firmly into an inner circumference of the main metal member, and then caulking the outer circumferential portion of the partition receiving plate with the first diaphragm to the main metal member, whereby a liquid sealed type vibration isolator provided with two auxiliary liquid chambers, two orifices and two diaphragms can be assembled easily. Especially, since the partition plate member pressing the second diaphragm to form the second auxiliary liquid chamber and orifice is fitted firmly in an engaged state around the outer circumference of the main partition member by a caulking device for the same outer circumference, the main partition member and the main partition plate member are combined with each other without a fear of their being separated from each other. This enables the second diaphragm to be pressed reliably, and can prevent an excessive decrease in the sealability of the parts and the short-circuiting of the passage as an orifice which are ascribed to changes with the lapse of time in the vibration isolating base member during the use thereof. In this liquid sealed type vibration isolator, a second metal fixing member covering a space on the outer side of the first diaphragm is provided, which is caulked with the partition receiving plate and first diaphragm to the main metal member, and these parts can also be combined together easily just as the above-mentioned parts. In the above-described vibration isolators, the main partition member is provided on the portion of an outer circumference thereof which is on the side of the first auxiliary liquid chamber with an orifice-forming recess, which are defined by the partition receiving plate and main metal member to form the first orifice. Therefore, the main partition member can be manufactured easily, and is suitable for practicing the vibration isolator. The partition plate member is preferably formed by fitting firmly the outer circumferential portion thereof around the outer circumference of the portion of the main partition member which is on the side of the main liquid chamber, bending at least a part of a circumferential end portion of the partition plate member inward in the above-mentioned orifice-forming recess, and caulking this bent portion to the main partition member. This enables the partition plate member to be caulked by utilizing the orifice-forming recess. The circumferential end portion of the partition plate member can be caulked at plural circumferentially spaced parts thereof to the main partition member, and also at substantially all parts of the circumference thereof to the same member. BRIEF DESCRIPTION OF THE DRAWINGS: Fig. 1 is a longitudinal sectional view showing one embodiment of the switchably controlled liquid sealed type vibration isolator according to the present invention; Fig. 2 is a perspective view showing constituent parts, which are in a mutually separated state, of a partition in the same embodiment; Fig. 3 is a sectional view of the same constituent parts which have not yet temporarily combined together; Fig. 4 is a sectional view of the same constituent parts which have been temporarily combined together; and Fig. 5 is a sectional view of a partition in another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS: Preferred embodiments of the switchably controlled liquid sealed type vibration isolator according to the present invention will now be described with reference to the drawings but the present invention is not limited to these embodiments. In this liquid sealed type vibration isolator A, a vibration isolating base member 2 formed of an elastic rubber member which receives a load of a power unit, such as an engine, etc. is joined to an upper opened side of a cylindrical main metal member 1, and a first metal fixing member 3 an upper end portion of the vibration isolating base member 2, as shown in the drawings. That is, the main metal member 1 is joined to the first metal fixing member 3 via the vibration isolating base member 2. In the illustrated vibration isolator, the vibration isolating base member 2 is formed to a substantially trapezoid-conical shape, and fixed air-tightly at an upper smaller-diameter end portion and a lower larger-diameter outer circumferential portion to the first metal fixing member 3 and the opened portion of the main metal member 1 respectively by a vulcanization bonding device. A first diaphragm 4 opposed to the vibration isolating base member 2 and formed of a rubber film, and a second metal fixing member 5 covering a space on the outer side of this diaphragm are fixed in a sealed state to a lower opened side of the main metal member 1 by a caulking device to be described later. A reference numeral 41 denotes an annular reinforcing member vulcanization bonded to the diaphragm 4. The first metal fixing member 3 is substantially disc-shaped, and a fixing bolt 31 fixed to a central portion of the first metal fixing member by a press fitting device or a welding device projects upward therefrom, by which fixing bolt 31 the first metal fixing member 3 is secured to a power unit of an automobile. A second metal fixing member 5 has a bottomed substantially cylindrical shape, and a flange-like opened edge portion 51 thereof is caulked with a partition, which will be described later, to a lower end portion 1a of the main metal member 1. A bottom wall portion 52 of the second metal fixing member 5 has a fixing bolt 53 fitted therein by a press fitting device so that the fixing bolt project downward therefrom. The second metal fixing member is positioned with respect to and secured to a vehicle body-side member by this fixing bolt 53. A space between the second metal fixing member 5 and first diaphragm 4 is formed as an air chamber 6. This air chamber is communicated with the atmosphere in some cases, and formed as an air-tight chamber in some cases. A partition 10 is air-tightly fitted in an inner circumference of the portion of the main metal member 1 which is between the vibration isolating base member 2 and first diaphragm 4, via a seal rubber layer 2a integral with the vibration isolating base member 2. An incompressible liquid, such as water or ethylene glycol is sealed in an inner chamber between the vibration isolating base member 2 and first diaphragm 4. This inner chamber is divided by the partition 10 so as to form a space between the vibration isolating base member 2 and partition 10 as a main liquid chamber 7, and a space between the first diaphragm 4 and partition 10 as a first auxiliary liquid chamber 8. The portion of the partition 10 which is on the side of the main liquid chamber 7 is provided therein with a second auxiliary liquid chamber 9, a change-over chamber 12 which is separated from the second auxiliary liquid chamber 9 by a second diaphragm 11, and which permits an atmospheric pressure and a negative pressure to be introduced thereinto switchably, and first and second orifices 13, 14 which communicate the main liquid chamber 7 with the first and second auxiliary liquid chambers 8, 9 respectively, and which have different liquid passage resistances. In the illustrated embodiment, the first auxiliary liquid chamber 8 communicates with the first orifice 13 having a higher liquid passage resistance (smaller cross-sectional area), and the second auxiliary chamber 9 communicates with the second orifice 14 having a lower liquid passage resistance (larger cross-sectional area). As shown in Figs. 1-4, the partition 10 includes a main partition member 15, a partition plate member 16 and a partition receiving plate 17, and has the following structure. The main partition member 15 is made integral of a metal material, such as aluminum, or a rigid material, such as a synthetic resin, and has an annular shape as shown in Fig. 2. The main partition member 15 is provided in the portion of an outer circumference thereof which is on the side of the first auxiliary liquid chamber 8 with an orifice-forming recess 19 so that a portion 18 on the side of the main liquid chamber 7 remains as a flange-shaped portion. The recess 19 is defined by the partition receiving plate 17 and main metal member 1, whereby the recess 19 is formed as the first orifice 13 which communicates the main liquid chamber 7 and the first auxiliary liquid chamber 8 with each other. The flange-shaped portion 18 is provided with a recessed communication section 13a which communicates the first orifice 13 and main liquid chamber 7 with each other. An upper inner portion, which is on the side of the main liquid chamber, of the main partition member 15 has a second diaphragm 11 to an outer circumferential portion of which an annular metal collar 20 is fixed by a vulcanization bonding device. The second diaphragm 11 is fixed coaxially with the central axis by press fitting the metal collar 20 into the main partition member 15. A clearance between the diaphragm 11 and main partition member 15 is formed as the change-over chamber 12 having a predetermined height. A reference numeral 12a denotes a projection for maintaining the clearance of not smaller than a predetermined height. In the illustrated embodiment, the central portion of an upper surface which corresponds to the change-over chamber 12 of the main partition member 15 is recessed curvilineally, and a groove 15b for press fitting the metal collar thereinto is formed around this recessed portion 15a. The diaphragm 11 is fixed to the main partition member so as to cover the recessed portion 15a by press fitting the metal collar 20 into the groove 15b. The change-over chamber 12 is joined to a change-over device (not shown), such as a valve, etc. which can be switchably connected to either a negative pressure source or an atmospheric pressure source via a communication passage 21 extending through an inner portion of the main partition member 15 and communicating at a side surface of the main metal member 1 with an outer portion thereof. Thus, either a negative pressure or an atmospheric pressure can be introduced into the change-over chamber by operating the change-over device in accordance with an instruction signal, etc. from a control unit. Owing to this arrangement, the second diaphragm 11 can be controlled in a switching manner to an operating condition and a non-operating condition. In order to work mainly the second orifice 14 of a lower liquid passage resistance (larger cross-sectional area), the second diaphragm 11 is maintained in a movable condition. In order to work the first orifice 13 of a higher liquid passage resistance, the movement of the second diaphragm 11 is stopped so as not to operate the second orifice 14 of a larger cross-sectional area. Thus, a sufficient damping effect can be displayed with respect to vibrations in different frequency regions, by the respective orifices 13, 14. The partition plate member 16 is a pressure molded product of mainly a steel plate, and has an annular projection 16a on a lower surface thereof. The partition plate member 16 is engaged with and fitted firmly in the main liquid chamber 7 of the main partition member 15 by a caulking device for the outer circumference of the main partition member 15 so as to seal the circumferential edge portion 11a of the second diaphragm 11 by pressing the same by the projection 16a. Thus, a space between the partition plate member 16 and the diaphragm 11 on the inner side of the projection 16a is formed as the second auxiliary liquid chamber 9, and a space on the outer side of this second auxiliary liquid chamber and defined by the main partition member 15 and partition plate member 16 as the second orifice 14 communicating the main liquid chamber 7 and second auxiliary liquid chamber 9 with each other via communication ports 23, 24 and having a comparatively large cross-sectional area. The first orifice 13 communicates with the main liquid chamber 7 through the communication port 23 of the second orifice 14. Namely, the first and second orifices 13, 14 have a common exit with respect to the main liquid chamber 7. The partition plate member 16 is engaged with and fitted firmly around the main partition member 15 by bending the outer circumferential portion 26 of the partition plate member 16 into a cylindrical portion of such a diameter that permits the cylindrical bent portion to be press fitted in the inner circumference of the main metal member 1, fitting firmly the outer circumferential portion 26 around the outer circumference of the flange-shaped portion 18 which is on the side of the main liquid chamber 1 of the main partition member 15, and bending inward in the orifice-forming recess 19 at least a part of the circumferential end section 26a of the outer circumferential portion 26 to thereby caulk the circumferential end section 26a to the flange-shaped portion 18. The caulking of the circumferential end section 26a is done preferably at substantially all parts of the circumference thereof, i.e., over the whole circumferential length of the recess 19 as shown in the drawings but the circumferential end section 26a can also be caulked partially at plural portions thereof spaced from one another at predetermined intervals to the main partition member 15. In this case, the portions to be caulked can be formed like projecting claws, and such claw-like members can be caulked. The outer circumferential portion 26 is provided with one or plural circumferentially spaced openings 22 for carrying out easily the replacement of the air and a liquid with each other when the partition plate member 16 is incorporated into the main metal member 1. The openings 22 are closed with a seal rubber layer 2a when the outer circumferential portion 26 of the partition plate member 16 is fitted firmly in the inner circumference of the main metal member 1. The partition receiving plate 17 is a pressure molded product obtained from a steel plate identical with the steel plate mentioned above, having an opening in the central portion thereof and formed of a doughnut-shaped disc of a diameter slightly larger than that of the main partition member 15. The partition receiving plate 17 positioned on the portion of the main partition member 15 which is on the side of the first auxiliary liquid chamber 8 is press fitted at an opened edge portion 28 in a central section thereof into the recess 25 provided in a lower surface of the main partition member 15, whereby the outer circumferential edge portion 27 is fixed firmly in the condition, in which the outer circumferential edge portion 27 projects outward beyond an outer edge of the main partition member 15, to the main partition member 15. In this condition, a recess 13b continuing from the recess 19 and an opening 17a are aligned with each other, so that the first orifice 13 communicates with the first auxiliary liquid chamber 8. In this structure, the partition 10 is in a temporarily assembled state as shown in Fig. 4, in which the outer circumferential portion 26 of the partition plate member 16 is press fitted liquid-tightly in the inner circumference of the main metal member 1 up to a position in which the outer circumferential portion 26 engages a circumferential edge portion 2b of the surface (lower surface in the drawing) on the side of the main liquid chamber of the vibration isolating base member 2. In addition, the outer circumferential edge portion 27 of the partition receiving plate 17 is caulked with the reinforcing member 41 of the first diaphragm 4 and opened edge portion 51 of the second metal fixing member 5 to the lower end portion 1a of the main metal member 1. In the case of the illustrated embodiment, a larger-diameter portion of the vibration isolating base member 2 has at a part of a circumferential section thereof a projection 2c reinforced with a part of the main metal member 1, and a part of a stabilizer 29 fixed to the first metal fixing member 3 with a common tightening member, etc. formed of a nut is disposed so as to extend near upper and lower surfaces of the projection 2c, and produce an effect of a stopper for restricting excessive vertical displacement of the projection 2c when the projection 2c is greatly displaced. In order to assemble the liquid sealed type vibration isolator 1 constructed as described above, the metal collar 20 is press fitted into the press fitting groove 15b first, in the recess 15a in the upper surface of the main partition member 15 in the atmospheric air, whereby the second diaphragm 11 is fixed so as to form the change-over chamber 12 between the second diaphragm 11 and main partition member 15. The partition plate member 16 opposed to the main liquid chamber-side portion of the main partition member 15 is press fitted in an engaged state at the outer circumferential portion 26 thereof around the outer circumference of the flange-shaped portion 18 of the main partition member 15, and caulked thereto by a caulking member provided at the circumferential end section 26a of the outer circumferential portion 26. Thus, the circumferential edge portion of the second diaphragm 11 is pressed by the projection 16a of the partition plate member 16, and the second auxiliary liquid chamber 9 and second orifice 14 are formed. The partition receiving plate 17 is fixed firmly at the press fitting portion in the central portion thereof to the portion of the main partition member 15 which is on the side (lower side) of the first auxiliary liquid chamber 8, whereby the partition 10 is tentatively assembled as shown in Fig. 4. During this time, the parts can be positioned as the positions of the orifice-forming openings and communication ports are ascertained visually with ease, and the tentative combining of the parts can be done reliably and easily without causing the parts to be displaced. Next, the partition 10 assembled tentatively as described above is press fitted and combined in a liquid tank into and with the main metal member 1, which is vulcanization bonded to the vibration isolating base member 2 into a unitary body, as the air is discharged. During this time, the outer circumferential portion 26 of the partition plate member 16 is press fitted firmly and liquid-tightly in the inner circumference of the main metal member 1 via the seal rubber layer 2a up to the position in which the outer circumferential portion 26 engages the circumferential edge portion 2b of the main liquid chamber-side surface (lower surface in the drawings) of the vibration isolating base member 2. After the air is extracted, the outer circumferential edge portion 27 of the partition receiving plate 17 may be caulked with the reinforcing member 41 for the first diaphragm 4 and the opened edge portion 51 of the second metal fixing member 5 to the lower end portion 1a of the main metal member 1. A liquid entering the change-over chamber 12 can be discharged by taking out the same from the liquid tank. When a rubber plug is inserted into the communication passage 21 before the assembling of the vibration isolator, the change-over chamber 12 can be secured usably by removing the rubber plug after the liquid is taken out from the liquid tank. This enables the switchably controlled liquid sealed type vibration isolator of Fig. 1 to be assembled easily which is formed so that a movement of the second diaphragm 11 on the side of the second auxiliary chamber 9 can be switchably controlled to a moving condition and a non-moving condition by a switching regulating operation for the introduction of a negative pressure and an atmospheric pressure into the change-over chamber 12, which is provided with the main liquid chamber 7, two, i.e. first and second auxiliary liquid chambers 8, 9, two, i.e. first and second orifices 13, 14, and two, i.e. first and second diaphragms 4, 11, and which is adjacent to the second auxiliary liquid chamber 9 joined to the second orifice 11 of a lower liquid passage resistance. In the vibration isolator thus assembled, the partition plate member 16 in particular which presses the second diaphragm 11 to form the second auxiliary liquid chamber 9 and second orifice 14 is fitted firmly in an engaged state around the outer circumference of the main partition member 15 by a caulking device for the same outer circumference. Therefore, the main partition member 15 and partition plate member 16 are combined together without a fear of their being separated from each other, and the second diaphragm 11 can be retained in a pressed state reliably. Accordingly, even when the fluctuation of the liquid pressure ascribed to the vibration of the vibration isolating base member, and permanent set in fatigue of parts due to heat occur, there is not the possibility that the deficiency of the sealability of parts and the short-circuiting of passages as orifices occur. When the partition plate member 16 is caulked to the main partition member 15 as mentioned above, the circumferential edge portion of the second diaphragm 11 can be held in a clamped state by the projection 16a between the projection 16a and the main partition member 15. Therefore, as shown in, for example, Fig. 5, this vibration isolator can also be practiced by clamping the circumferential edge portion of the second diaphragm 11 by the projection 16a and main partition member 15 with the metal collar 20 of the second diaphragm 11 omitted. As described above, in the switchably controlled liquid sealed type vibration isolator according to the present invention, the inner partition dividing the inner chamber into the main liquid chamber and two auxiliary liquid chambers is formed so that the partition can be assembled temporarily in the air. This enables the plural constituent parts to be combined together reliably and easily without causing the parts to be dislocated, the relative displacement of the constituent parts in a vehicle-mounted state due to the variation thereof with the lapse of time to be reduced, and the sealed condition of the parts to be retained in an excellent condition, and can contribute to the improvement of the durability of the vibration isolator.

Claims: A switchably controlled liquid sealed vibration isolator comprising a vibration isolating base member (2) formed of an elastic rubber member, a first metal fixing member (3) combined with one of upper and lower portions of the vibration isolating base member (2), a main cylindrical metal member (1) combined with the other portion of the vibration isolating base member (2), a first diaphragm (4) fixed to the main metal member so as to be opposed to the vibration isolating base member (2), a partition (10) provided between the vibration isolating base member (2) and first diaphragm (4), a main liquid chamber (7) formed between the partition (10) and vibration isolating base member (2), a first auxiliary liquid chamber (8) formed between the partition (10) and first diaphragm (4), a second auxiliary liquid chamber (9) formed on a main liquid chamber-side portion of the partition (10), a change-over chamber (12) separated from the second auxiliary chamber (9) via a second diaphragm (11) and capable of introducing thereinto an atmospheric pressure and a negative pressure in a switchable manner, and first and second orifices (13, 14) communicating the main liquid chamber (7) with the first (8) and second (9) auxiliary chambers respectively, the partition (10) having at an outer circumferential portion thereof a main partition member (15) forming the first orifice (13), and the second diaphragm (11) being provided on a main liquid chamber-side portion of the main partition member (15) so as to form the change-over chamber (12) in a diametrically inner portion thereof, characterized by a partition plate member (16) which presses a circumferential portion of the second diaphragm (11) toward the main partition member (15) to form the second auxiliary liquid chamber (9) between the partition plate member and the second diaphragm (11) and is engaged with and fitted firmly around an outer circumferential portion of the main partition member (15) by a caulking device of this outer circumferential portion, a portion defined by the main partition member (15) and partition plate member (16) on an outer side of the second auxiliary liquid chamber (9) being formed as the second orifice (14), and a partition receiving plate (17), an outer circumferential edge portion of which extends outward beyond an outer end of the main partition member (15) and which is fixed by a press fitting device with respect to the main partition member (15) to the portion of the main partition member (15) which is on the side of the first auxiliary liquid chamber (8), the partition plate member (16) being fitted liquid-tightly in an inner circumferential portion of the main metal member (1), and the outer circumferential edge portion of the partition receiving plate (17) being fixed with the first diaphragm (4) to the main metal member (1) by a caulking member. A vibration isolator according to claim 1, wherein a second metal fixing member (5) covering a space on the outer side of the first diaphragm (4) is provided, the second metal fixing member being caulked with the partition receiving plate (17) and first diaphragm (4) to the main metal member (1). A vibration isolator according to claim 1 or 2, wherein the main partition member (15) is provided on the portion of an outer circumference thereof which is on the side of the first auxiliary liquid chamber (8) with an orifice-forming recess (13), which is defined by the partition receiving plate (17) and main metal member (1) to form the first orifice (13). A vibration isolator according to any of claims 1 to 3, wherein the partition plate member (16) is fitted firmly at an outer circumferential portion thereof around an outer circumference of the portion of the main partition member (15) which is on the side of the main liquid chamber (7), at least a part of a circumferential end portion of the partition plate member (16) being bent in the orifice-forming recess in the inward direction and thereby caulked to the main partition member (15). A vibration isolator according to claim 4, wherein the circumferential end portion of the partition plate member (16) is caulked at plural circumferentially spaced parts thereof to the main partition member (15). A vibration isolator according to claim 4, wherein the circumferential end portion of the partition plate member (16) is caulked at substantially all circumferential parts thereof to the main partition member (15).

Inventors: HASHIMOTO TSUTOMU, TAKASHIMA YUKIO, HASHIMOTO, TSUTOMU, TAKASHIMA, YUKIO, Hashimoto, Tsutomu, Toyo Tire &amp; Rubber Co., Ltd., Takashima, Yukio, Toyo Tire &amp; Rubber Co., Ltd.
Applicants: TOYO TIRE & RUBBER CO, TOYO TIRE & RUBBER CO., LTD .
Application year: 2000
Main classification: F16F13
IPC codes: F16F13, B60K5