Fluid-filled mount

Abstract: A fluid-filled mount using an elastic body and a viscous fluid to obtain a great damping force has for its object to facilitate the filling of the viscous fluid and to considerably improve the sealability, and comprises a case having a mounting plate (16) with mounting holes and fixing claws (13C) together with a cup (13), a cylindrical case having a mounting plate with mounting holes together with a cylinder, a stud (18) having an axial through hole (14A) for viscous fluid filling and also having a tapped hole provided in one end of its axial through hole and a damping plate is fixed to its other end, and an elastic body (17) having the said cylindrical case (16) embedded in it and the said stud secured in its center hole.

Description: BACKGROUND OF THE INVENTION This invention relates to an anti-vibration fluid-filled mount which, in an industrial vehicle or construction equipment, such as dump truck or power shovel, serves to hold the cab as a vibration protector on the body frame subjected directly to vibrations. At present, cabs of industrial vehicles, such as dump trucks, and those of construction equipment, such as power shovels, need comfortable roominess and high operability, and even a gentle-to-operator, roundish design. Further, as the traveling speed of such vehicles and equipment is made increasingly high, a higher-performance cab mount surpassing a rubber-made mount is also needed to improve the cab vibrations. In the accompanying drawings, FIG. 17 is a view in section showing a conventional fluid-filled mount 100. In this figure, 101 is a case which comprises a mounting plate 102, a cylinder 103 having a flange 103A at its bottom, and a cup 105 containing a viscous fluid 104, such as silicone oil. The said mounting plate 102 has a coupling hole 102A at its center, as well as mounting holes 102B. In the said coupling hole 102A, the top end of the cylinder 103 is inserted and solidly secured to the said mounting plate by means of welds 106. The said cup 105 has its brim 105A solidly fixed to the flange 103A of the said cylinder 103, for example by caulking. 107 is a stud bolt, to the bottom end of which a damping plate 108 is secured by means of a nut 109. On the rim of the said damping plate 108, elastic stops 108A are provided. 110 is a plug which is fitted in a filling hole 105B provided to fill the said cup 105 with the said viscous fluid 104. 111 is a cylindrical elastic body having a central hole 111A, where the said stud bolt 107 is inserted and secured by heat glueing. The girth of the said cylindrical elastic body 111 is secured to the bore of the said cylinder 103 by heat glueing. The bottom surface of the overhang 111B of the said cylindrical elastic body 111 is secured onto the top surface of the said mounting plate 102 by heat glueing. On the top end of the stud bolt 107 of such fluid-filled mount 100, such cab 5 of a dump truck 1 as shown in FIG. 18 and FIG. 19 is fitted. FIG. 18 shows the setup of a common dump truck 1 as an example of industrial vehicles, while FIG. 19 is a detail of P in FIG. 18. Brackets 3, 8 are fastened to the frame 2 of the dump truck 1, and the cab 5 has its floor 6 fitted to each of the brackets 3, 8 through the aforesaid fluid-filled mount 100 so as to prevent the transmission of vibrations from road surface and others directly to the cab 5. In such case, to each of the said brackets 3, 8, the mounting plate 102 of the fluid-filled mount 100 is fastened by means of bolts 128 and nuts 129, using the aforesaid mounting holes 102B, while the the stud bolt 107 of the fluid-filled mount 100 is fastened to the floor 6 by means of a nut 131 to mount the cab 5 in a vibration-proof manner. In FIG. 18, 7 is a tire of the dump truck. In the following, the buffer operation of the fluid-filled mount 100 of the above-mentioned setup is described. When the aforesaid dump truck 1 is driven, vibrations are exerted on the truck body from the tires 7. Such vibrations are then transmitted to the aforesaid case 101. As the case 101 moves under the vibrations transmitted, the viscous fluid 104 is stirred, and the viscous resistance of the viscous fluid 104, coupled with the damping plate 108, affords a buffer action to damp the vibrations. Thus, the vibrations transmitted to the cab 5 can be reduced. The load of the cab 5 can be supported by the cylindrical elastic body 111. However, the conventional fluid-filled mount 100 has an inconvenience. If it is given an impact from the outside or dropped onto a floor because of mishandling, the plug 110, which is located on the bottom of the case 101, may come out to allow the viscous fluid 104 to leak, or the caulking securing the brim 105A of the cup 105 to the flange 103A of the cylinder 103 may come loose to reduce the sealability. Another inconvenience of the conventional fluid-filled mount is that, when great shocks are exerted on it from the outside, the pressure of the viscous fluid contained in it increases so abruptly that it cannot absorb the first great shock to transmit such shock to the cab 5. FR-A 2 356 847 discloses a fluid-filled mount according to the precharacterizing part of claim 1. SUMMARY OF THE INVENTION This invention is made to eliminate such inconveniences of prior arts. The object of this invention is to provide a fluid-filled mount which is simplified in construction for easier filling of viscous fluid while permitting to greatly improve the sealability. In order to achieve such object, there is provided a fluid-filled mount according to claim 1. The further claims are related to adventageous aspects of the invention. According to such setup, the viscous fluid filling can be made easier and the sealability can greatly be improved. Another object of this invention is to improve the shock absorbing characteristics of a fluid-filled mount. In order to achieve such object, the fluid-filled mount according to this invention comprises a damping plate being provided at a given location with at least one through hole, and a valve for high impact on the said damping plate. According to such setup, when a great impact is exerted on the fluid-filled mount from the outside, the abrupt rise of pressure of the viscous fluid during the first one of the corresponding vibrations can be prevented. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view in section showing an embodiment of the fluid-filled mount according to this invention. FIG. 2 is a plan view showing the fluid-filled mount of FIG. 1. FIG. 3 is a perspective view showing in detail the case of the fluid-filled mount of FIG. 1. FIG. 4(A) is a view in section showing in detail the stud and the damping plate of the fluid-filled mount of FIG. 1. FIG. 4(B) is a plan view showing in detail the stud and the damping plate of the fluid-filled mount of FIG. 1. FIG. 5(A) is a perspective view showing in detail the cylindrical case of the fluid-filled mount of FIG. 1 as seen from the top. FIG. 5(B) is a perspective view showing in detail the cylindrical case of the fluid-filled mount of FIG. 1 as seen from the bottom. FIG. 6 is a view in section showing the elastic body of the fluid-filled mount of FIG. 1 as integrated with the he stud fitted with the damping plate and also integrated with the cylindrical case. FIG. 7 is a view in section showing another embodiment of the fluid-filled mount according to this invention. FIG. 8 (A) is a view in section showing in detail the stud, the damping plate and the valve for high impact of the fluid-filled mount of FIG. 7. FIG. 8(B) is a plan view showing in detail the stud, the damping plate and the valve for high impact of the fluid-filled mount of FIG. 7. FIG. 9 is a plan view showing in detail the valve for high impact of the fluid-filled mount of FIG. 7. FIG. 10 is a view in section showing the elastic body of the fluid-filled mount of FIG. 7 as integrated with the he stud fitted with the damping plate and the valve for high impact, and also integrated with the cylindrical case. FIG. 11 is a view in section for description of the operation of the fluid-filled mount of FIG. 7. FIG. 12 is a plan view showing in detail another embodiment of the valve for high impact of FIG. 9. FIG. 13 is a plan view showing in detail the third embodiment of the valve for high impact of FIG. 9. FIG. 14 is a diagram showing the load and displacement of the damping plate for the fluid-filled mount of FIG. 7 and for the conventional fluid-filled mount. FIG. 15 is a view in section showing the third embodiment of the fluid-filled mount of this invention. FIG. 16 is a view in section showing the fourth embodiment of the fluid-filled mount of this invention. FIG. 17 is a view in section showing in detail the conventional fluid-filled mount. FIG. 18 shows the setup of a dump truck. FIG. 19 is a detail of P in FIG. 18. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following, the embodiments of this invention is described in detail with reference to the accompanying drawings. FIG. 1 is a view in section showing an embodiment of the fluid-filled mount 10 of this invention. In this figure, 13 is a case. As can be seen in its perspective view given in FIG. 3, this case 13 comprises a cup 13A and a mounting plate 13D which has mounting holes 13B and fixing claws 13C. 14 is a stud. As can be seen in its detailed view in section and plan view given in FIG. 4(A) and FIG. 4(B), respectively, this stud 14 is provided axially with a through hole 14A for filling of viscous fluid 4 and a tapped hole 14B. 15 is a damping plate. As shown in FIG. 1 and FIG. 4, this damping plate 15 is provided at its center with an opening 15A. In this opening 15A, one end of the said stud 14 is inserted and solidly fixed by caulking or other means. 16 is a cylindrical case. As can be seen in its detailed perspective views given in FIG. 5(A) and FIG. 5(B), this cylindrical case comprises a cylinder 16A and a mounting plate 16C which has mounting holes 16B. 17 is an elastic body, such as rubber. As shown in FIG. 1 and FIG. 6, the said cylindrical case 16 is enveloped in this elastic body 17. The bottom surface of the elastic body 17 has a cavity 17A serving to complicate the flow of the viscous fluid 4. 18 is a stud bolt. On one end of this stud bolt 18, a thread 18A is cut. This thread 18A is used to secure a vibration protector which is a cab 5 shown in FIG. 18 and FIG. 19. On the other end of the stud bolt 18, another thread 18B is cut. This thread 18B is screwed in the tapped hole 14B of the stud 14. 19 is an anti-rotation pin. This anti-rotation pin is fitted on the top of the stud 14. The aforesaid elastic body 17 has its girth 17B tapered as shown in FIG. 6. Such taper allows the elastic body to come in tight contact with the inside wall surface of the cup 13A of the aforesaid case 13. The top rim of of the elastic body 17 acts as a stop for the cab 5, while its bottom rim, as a stop for the damping plate. In the following, the procedure for assembling the fluid-filled mount of the above-mentioned setup is described. First, the elastic body 17 is formed while enveloping the cylindrical case 16 therein and then, the stud 14 is inserted into the center hole of the elastic body 17 and secured there by heat glueing or other means. The stud 14, the damping plate 15, the cylindrical case 16 and the elastic body 17 are thus integrated into an subassembly. This subassembly is inserted into the cup 13A of the case 13 in such manner that the tapered girth comes in tight contact with the inside wall surface of the cup 13A. By bending and caulking the fixing claws 13C of the case 13 so as to securely clamping the edges of the mounting plate 16C of the cylindrical case 16, the case 13 and the cylindrical case 16 can be fixed together solidly. Since the top end 17B1 of the tapered girth 17B of the elastic body 17 is then pinched and compressed in between the bend in the form of curved surface of the cylindrical case 16 and the bend in the form of curved surface of the cup 13B of the case 13, the tight contact of the elastic body 17 is ensured and the fluid leakage can completely be prevented. Then, the viscous fluid 4 is injected through the center hole 14A provided in the center of the stud 14. Thereafter, the bolt 18 is screwed in the tapped hole 14B of the stud 14 to seal the viscous fluid 4. On the other end of the stud 14, the cab 5 is fitted in such manner as shown in FIG. 19. Since the mounting holes 13B in the mounting plate 13D of the case 13 are in register with the mounting holes 16B in the mounting plate 16C of the cylindrical case 16, the fluid-filled mount 100 can be fitted to the bracket 8 of the dump truck 1 by means of the aforesaid bolts 128 and nuts 129 in such manner as shown in FIG. 19. Thus, the case 13 and the cylindrical case 16 can firmly be held together, including the fixing claws 13C. In addition, because the mounting plate 13D of the case 13 and the mounting plate 16C of the cylindrical case 16 become integral with each other, the strength is increased. This makes it unnecessary to use a thick mounting plate as is the case with the conventional fluid-filled mount. As described above, according to the fluid-filled mount 10 of this invention, the viscous fluid 4 can be injected through the center hole of the stud 14. This means that the setup of the cup 13A of the case 13 can be simplified and that its manufacturing cost can be reduced. Further, because of excellent sealability, the leakage of the viscous fluid 4 can dependably be prevented. In the following, the fluid-filled mount 10 of another embodiment of this invention as shown in FIG. 7 to FIG. 14 is described. In this embodiment, as shown in FIG. 7 and FIG. 8(A) and (B), the damping plate 15 has, in addition to the central opening 15A, four openings 15B therearound, for example. And, in the central opening 15A, one end of the stud 14 is inserted and, at the same time, a valve for high impact 20 as hereinafter described is solidly secured on the damping plate 15 by co-fastening or other means. In the following, the procedure for assembling the fluid-filled mount 10 of this embodiment (FIG. 7) is described. First, the elastic body 17 in which the stud 14 and the cylindrical case 15 are enveloped is formed in the same manner already described for the aforesaid embodiment. Then, the valve for high impact 20 and the damping plate 15 are secured by the above-mentioned co-fastening or other means to integrate the stud 14, the damping plate 15, the cylindrical case 16, the elastic body 17 and the valve for high impact into a subassembly as shown in FIG. 10. This subassembly is inserted into the cup 13A of the case 13 in such manner that the tapered girth of the elastic body 17 comes into tight contact with the inside wall surface of the cup 13A. The description of the next and succeeding steps is omitted because they are similar to those already described for the aforesaid embodiment (FIG. 1). In the following, the damping operation of the fluid-filled mount of FIG. 7 is described. During driving of the aforesaid dump truck 1, when high impact is applied from the tires 7 directly to the truck body, such impact is transmitted to the case 13 to stir the viscous fluid 4. As a result, the viscous resistance of the viscous fluid 4 and the damping plate 15 afford a shock absorbing action to damp the impact vibrations. Thus, vibrations transmitted to the cab 5 can be reduced. In the initial period of such impact, the pressure of the viscous fluid 4 rises abruptly, but this viscous fluid 4 under increased pressure lifts the arm 20B of the valve 20 for high impact made of spring material, through the four openings 15B in the damping plate 15, as shown in FIG. 11. As a result, the viscous fluid flows through the four openings 15B in the damping plate 15 into the cavity on the opposite side to allow considerable absorption of the first shot of impact vibration. Such action is described with reference to FIG. 14, in comparison with the conventional fluid-filled mount. FIG. 14 shows the relation between the load and the displacement of the damping plate of fluid-filled mount during impact compression (by a solid line for the fluid-filled mount of this invention and by a dot-and-dash line for the conventional fluid-filled mount). When impact is exerted on the damping plate, this plate moves in the compression direction (that is, direction in which the damping plate is thrusted into the viscous fluid). At the maximum speed of this damping plate, the load on it becomes maximum. In the damping plate 15 of the fluid-filled mount of this invention, the valve 20 for high impact is provided to reduce the fluid pressure. This means that the maximum load is smaller in the fluid-filled mount of this invention that in the conventional one. Then, under the fluid pressure, the damping plate speed is slowed down. The point where this speed becomes zero corresponds to the maximum displacement of the damping plate in the compression direction. In order to reduce the rate of transmission of steady-state vibrations during resonance of the fluid-filled mount, it is preferred to get greater damping of displacement of the damping plate 15. In general, this can be achieved by restricting the fluid flow path (clearance between the elastic body 17 and the damping plate 15). However, for such high impact as may be encountered for example when a tire falls into a big depression, if the fluid flow path is restricted excessively, the fluid pressure under the damping plate 15 becomes too high and the instantaneous load becomes greater. Notwithstanding, according to this invention, since the damping plate 15 is provided with the valve 20 for high impact to reduce the fluid pressure in the compression direction (direction in which the damping plate 15 is thrusted into the viscous fluid 4) as described above, damping can be moderated so as to reduce the instantaneous load (which is the maximum load shown in FIG. 14). On the other hand, during tension (that is, in the direction in which the damping plate 15 is pulled up from the viscous fluid 4), practically the same magnitude of damping as that in the conventional fluid-filled mount can be maintained. An example of the damping plate 15 wherein four openings 15B are provided is given in the above description. Naturally, the embodiment of this invention of FIG. 7 is not limited only to such example, and either one to three, or five or more openings 15B may be provided in the damping plate 15 according to the desired damping characteristics. From this, it follows that the arms 20B of the valve 20 for high impact are provided correspondingly to the number of such openings 15B. As for the shape of the valve for high impact 20, it may naturally be either a disk with slits 21 as shown in FIG. 12 or a mere disk as shown in FIG. 13. Further, the construction of the fluid-filled mount 10 referred to in the above description features a case 13 comprising mounting holes 13B and fixing claws 13C, damping plate 15 and cup 13A containing viscous fluid 4, and directly receiving vibrations from the outside; a cylindrical case 16 comprising mounting plate 16C having mounting holes 16B, and cylinder 16A; a stud 14 having an axial through hole 14A for filling of viscous fluid 4, a tapped hole 14B being provided in the said through hole 14B at one end of the said stud 14, and the said damping plate 15 being fixed to the other end of the said stud 14; and an elastic body 17 having the said cylindrical case 16 embedded in it and the said stud 14 secured in its center; the said clastic body 17 fitted solidly with the said stud 14 having the said damping plate 15 fixed to its end, and also with the said cylindrical case 16, being locked in the said cup 13A of the said case 13; and the said fixing claws of the said case 13 being bent onto the mounting plate 16C of the said cylindrical case 16. However, this invention is not limited only to such construction and can naturally be applied to various constructions of fluid-filled mount. As described above, according to the fluid-filled mount 10 of FIG. 7, when such mount receives a high impact from the outside, the abrupt pressure rise of the viscous fluid 4 during the first shot of impact vibration can be prevented, so that the cab 5 can effectively be protected from vibration. In the following, such other embodiments of the fluid-filled mount 10 of this invention as shown in FIG. 15 and FIG. 16 are described. A taper formed on its edge realizes this in the embodiment of FIG. 15. In these figures, 23 is a cup-like plug which is fitted in the through hole 14A of the stud 14 to enhance the sealability. As for the shock absorbing operation of the fluid-filled mount 10 of such setup, its damping ability can effectively be maintained even during continuous application of wide-amplitude vibrations. To be more exact, when the damping plate 15 moves downwards, the viscous fluid 4 smoothly flows toward the top surface side of the damping plate 15 thanks to the taper formed on its edge and, when the damping plate 15 moves upwards, it holds the viscous fluid 4 on its top surface. In this way, the pressure in the upper and lower fluid chambers is equalized. Thus, the damping plate 15 can always be in the viscous fluid 4 to effectively maintain its damping ability. FIG. 16 is a view in section showing the fourth embodiment of the fluid-filled mount 10 according to this invention. It is natural that the same damping operation described for FIG. 15 is obtained in the fluid-filled mount 10 of FIG. 16. The stepped damping plate 15 may naturally be made by sticking two plates of different diameters together. According to such setup, the damping ability for wide-amplitude vibrations can effectively be maintained by only changing the shape of the edge of the damping plate 15.

Claims: A fluid-filled mount (10) for obtaining a damping force, comprising a case (13) having a mounting plate (13D) with first mounting holes (13C) and fixing claws (13C), and a cup (13A) containing a viscous fluid (4); a stud (14) having an axial through hole (14A) for filling of said viscous fluid (4), a tapped hole (14B) provided at one end of the axial through hole (14A) and a damping plate (15) fixed to the other end of the stud (14); and an elastic body (17) sealingly locked in the cup (13A) and integral with said stud (14), the stud (14) being secured in a center hole of the elastic body (17); characterized in that an inner case (16) having a cylindrical portion (16A) and a second mounting plate (16C) is integrally embedded in the elastic body (17); said second mounting plate (16C) comprises second mounting holes (16B) and is arranged adjoining the first mounting plate (13D) so that said first and second mounting holes (13B, 16B) are in register with each other; and the first mounting plate (13D) comprises said fixing claws (13C) bent onto the second mounting plate (16C) to fix the outer and inner cases (13, 16) together. The fluid-filled mount of claim 1 wherein the elastic body (17) has its lateral surface tapered and its top fringe surface acts as a stop of a vehicle cab (5), while its bottom fringe surface acts as a stop for the damping plate (15). A fluid-filled mount of claim 1 wherein said damping plate (15) is provided with at least one through hole (15B) at a given position and a valve (20) for high impact is provided on the said damping plate. The fluid-filled mount of claim 3 wherein said valve (20) for high impact is made of spring material. The fluid-filled mount of claim 1 wherein a cup-like plug (23) is fitted in the through hole (14A) of the stud (14) to enhance the sealability. The fluid-filled mount of claim 1, wherein the damping plate (15) is flat and has on its radially outer and bottom surface area a surface of reduced diameter forming a stepped edge, whereas the upper surface area is flat. The fluid-filled mount of claim 1, wherein a radially outer portion of the flat damping plate (15) has a cup-like form opened towards the top with a flat radially outermost surface connecting the tapered surface of the radially outermost bottom surface of the cup-like shaped damping plate (15) with the tapered top surface of the cup-like shaped damping plate (15).

Inventors: KUZUKAWA MITSUO, TANAKA TATSUO, KUZUKAWA, MITSUO, TANAKA, TATSUO
Applicants: FUKOKU KK, FUKOKU CO., LTD.
Application year: 1995
Main classification: F16F13
IPC codes: F16F13, B62D27