JP2010196874A - Liquid-filled vibration isolator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high damping action over an unconventionally wide frequency area, by elaborating a device in a structure of a liquid chamber and an orifice channel in a liquid-filled vibration isolator. <P>SOLUTION: This liquid-filled vibration isolator includes a first orifice channel P1 communicating between a pressure receiving chamber f1 and a balancing chamber f2 and a second orifice channel P2 communicating between the balancing chamber f2 and an intermediate liquid chamber f3. A communicating hole 42a of a predetermined dimension is arranged in a membrane 42 for partitioning the pressure receiving chamber f1 and the intermediate liquid chamber f3. The pressure receiving chamber f1 and the intermediate liquid chamber f3 are substantially communicated to vibration of a relatively low frequency, and the high damping action is provided by a virtual orifice channel where the two orifice channels P1 and P2 are put together. A gradual transition is made to a damping characteristic of the second orifice channel P2 only, as a vibration frequency increases. Thus, the sufficient damping action is provided over the novel wide frequency area. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid-filled vibration isolator that damps vibrations by the flow resistance of the liquid sealed inside, and particularly relates to the structure of a liquid chamber and an orifice passage.

  Conventionally, an automobile engine mount is well known as this type of vibration isolator. The basic structure is that the first connection fitting on the engine side (supported side) and the second connection fitting on the vehicle body side (support side) are connected by a rubber elastic body, and the volume is increased as the rubber elastic body is deformed. A plurality of liquid chambers are formed between the two connecting metal fittings so as to change, and they are communicated by the orifice passage. By utilizing the resonance phenomenon of the liquid flowing through the orifice passage, engine vibrations in a predetermined frequency range can be effectively absorbed and attenuated.

  Here, in general, since an engine for an automobile is used over a wide driving range, an engine mount is required to have an anti-vibration effect against vibration inputs having different frequencies and amplitudes. The frequency of vibration that is effectively absorbed and attenuated by the flow of liquid in the orifice passage is largely determined by the cross-sectional area and length of the orifice passage, and only one orifice passage is sufficient for several types of vibration inputs. It is not possible to obtain an effective anti-vibration effect.

  Thus, for example, Patent Documents 1 and 2 disclose that two orifice passages having different cross-sectional areas and lengths are provided and tuned to different frequency ranges. That is, the vibration isolator described in the literature 1 forms the second sub liquid chamber on the main liquid chamber side of the partition member that partitions the main liquid chamber and the first sub liquid chamber, The first orifice passage communicating with the first sub-liquid chamber is, for example, shake vibration with a frequency of less than 15 Hz, and the second orifice passage communicating with the first and second sub-liquid chambers is, for example, with a frequency of 20-40 Hz. Each is tuned to idle vibration.

  Further, for example, for vibration input exceeding a frequency of 40 Hz, the fluid pressure fluctuation in the main liquid chamber is absorbed by deformation of the elastic membrane member (membrane) that partitions the main liquid chamber and the second sub liquid chamber. As a result, it is possible to reduce the noise of the vehicle interior.

In the liquid-filled vibration isolator described in Patent Document 2, the second sub-liquid chamber in the partition member that partitions the main liquid chamber and the first sub-liquid chamber is the first opposite to that of Patent Document 1. It is formed on the side of the secondary liquid chamber and is partitioned from the first secondary liquid chamber by a rubber second diaphragm. The first orifice passage is tuned to shake vibration around 10 Hz, and the second orifice passage is tuned to idle vibration around 20 to 30 Hz.
Japanese Patent No. 3461913 Japanese Patent No. 3563309

  Incidentally, in recent years, in order to further improve the ride comfort of automobiles, there is a demand for increasing the attenuation in the frequency range higher than the conventional shake vibration in the engine mount. If it is shifted slightly to the high frequency side, this merely changes the frequency range having a high damping action, and the damping action of the shake vibration is reduced, so that it is not very effective.

  If a third orifice passage having characteristics intermediate between the first and second orifice passages is provided, the dynamic spring rapidly rises in the frequency range of idle vibration due to the influence of the resonance of the liquid here (so-called dynamic movement). In the first place, it is not practical to provide three sub liquid chambers and three orifice passages in a limited space of the engine mount.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a liquid-filled vibration isolator suitable for, for example, an automobile engine mount and the like, which has a high damping action over a wide frequency range that has not been conventionally available. It is to provide the resulting structure.

  In order to achieve the above-described object, the present invention includes first and second orifice passages, which are not simply switched depending on the frequency of the input vibration, but have a wide frequency range by the interaction described below. A damping action is obtained over the entire area.

  Specifically, in the first aspect of the invention, the volume of the first connection fitting on the supported side, the second connection fitting on the support side connected to the first connection fitting by the rubber elastic body, and the volume of the rubber elastic body change as the rubber elastic body is deformed. In this way, a liquid-filled vibration isolator including a main liquid chamber formed between both metal fittings and a first sub liquid chamber communicated with the main liquid chamber by a first orifice passage is an object. .

  And like the above-mentioned conventional example (patent documents 1), it is provided with the 2nd subfluid chamber connected with the 1st subfluid chamber by the 2nd orifice passage, and the 2nd orifice passage is At least one of the first orifice passage and the cross-sectional area is shorter than the first orifice passage, and the main liquid chamber and the second sub liquid chamber are partitioned by an elastic film member. A communication hole having a predetermined size is provided so as to allow the two liquid chambers to communicate with each other.

  With this configuration, in the above-described vibration isolator, first, when the rubber elastic body is deformed by a relatively low-frequency vibration input and the volume of the main liquid chamber changes periodically, this causes the first orifice passage to pass through. Thus, the liquid flows between the first sub liquid chamber and the liquid flows between the first sub liquid chamber and the second sub liquid chamber via the second sub liquid chamber and the second orifice passage. This is because the flow rate of the liquid generated by the low-frequency vibration input is relatively low. At this time, the main liquid chamber and the second sub liquid chamber are substantially communicated with each other through the communication hole of the elastic membrane member. Will be.

  This state can be considered that the main liquid chamber and the first sub liquid chamber are communicated with each other by one virtual orifice passage including the first and second orifice passages. Due to the resonance of the liquid, as shown in phantom lines in FIG. 4, the first and second orifice passages each have a higher attenuation in the middle frequency range of each single peak (indicated by the dashed line in the figure) than either of them. The peak of action appears.

  That is, although the original damping action cannot be obtained near the resonance frequency of the first orifice passage, a high damping action can be obtained in a wide range from there to the high frequency side. However, as the frequency increases, the liquid gradually becomes difficult to flow through the first orifice passage (so-called clogging), and the elastic membrane member that communicates the main liquid chamber and the second sub liquid chamber. Since the communication hole also becomes difficult to flow, the damping action due to the virtual orifice passage is gradually lost, and the damping action due to the resonance of the liquid in the second orifice passage becomes dominant.

  Thus, the present invention gradually shifts from the damping characteristic of the virtual orifice passage combining the first and second orifice passages to the damping characteristic of the second orifice passage alone according to the frequency of the input vibration. Thus, as shown by the solid line and the broken line in the figure, the conventional method can be obtained only in the vicinity of the resonance frequency of the orifice passage over a wide range from the vicinity of the resonance frequency of the first orifice passage to the vicinity of the resonance frequency of the second orifice passage. High damping effect can be obtained.

  Therefore, when the vibration isolator of the present invention is applied to an engine mount of an automobile, the first orifice passage is tuned to a frequency range lower than the shake vibration, for example, around 5 Hz, while the second orifice passage is subjected to idle vibration as in the prior art. By tuning together, a sufficient vibration damping action can be obtained over a wide frequency range covering from shake vibration to idle vibration.

  In addition, since the orifice passage functions over a wide frequency range, so-called dynamic spring jump does not occur in this frequency range. Therefore, it is possible to effectively absorb and attenuate vibrations in the intermediate frequency range while absorbing and attenuating shakes, idle vibrations, and the like more than before, thereby improving the riding comfort of the vehicle.

  Preferably, a partition member for partitioning the main liquid chamber and the first sub liquid chamber is provided, and the second sub liquid chamber and the first and second orifice passages are formed in the partition member ( In this way, the structure of the vibration isolator can be simplified.

  More specifically, one of the first and second connection fittings has a columnar shape extending in the main load input direction, and the other has a cylindrical shape separated from the outer peripheral side of the one connection fitting. The partition member is fitted inside the other connecting fitting, and a main liquid chamber is defined on one side of the main load input direction, and a first sub liquid chamber is defined on the other side. Then, the partition member is formed with a recess that faces the main liquid chamber, and the opening is covered with the elastic film member to form the second sub liquid chamber. It is preferable to form a communication hole in (Claim 3).

  In this way, it is easy to ensure a relatively large area of the elastic membrane member, and the cross-sectional area of the communication hole formed at the approximate center is too large even if the elastic membrane member is deformed due to fluctuations in hydraulic pressure. Since it does not fluctuate, it is advantageous in obtaining the above-described effects of the invention stably.

  That is, the cross-sectional area of the communication hole has a great influence on the appearance of the above-described damping action. Specifically, the larger the cross-sectional area of the communication hole is, the closer to the attenuation characteristic by the virtual orifice passage, The smaller the cross-sectional area of the communication hole, the closer to the characteristics of the first and second orifice passages. As a result of the experiment, the inventor has obtained the above-described effect of the invention by obtaining a diameter of the communication hole of 2.0 to 10.0 mm when the thickness of the elastic membrane member is about 1.0 to 5.0 mm. It has been found that the thickness is preferably about 3.0 to 6.0 mm (claim 4).

  As described above, according to the liquid-filled vibration isolator according to the present invention, when the frequency of the input vibration is relatively low due to the interaction between the first and second orifice passages, a virtual combination of both is provided. Since the damping action by the orifice passage is obtained, and the frequency of the input vibration is gradually increased, the damping action of the second orifice passage is gradually shifted. Therefore, it is sufficient over an unprecedented wide frequency range. A damping action can be obtained.

  Therefore, for example, when used as an engine mount of an automobile, engine vibration can be effectively absorbed and attenuated from so-called shake vibration to idle vibration, and the riding comfort of the vehicle can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. It should be noted that the following description of the preferred embodiment is merely illustrative in nature, and is not intended to limit the present invention, its application, or its use.

(Embodiment 1)
FIG. 1 shows an embodiment in which a liquid-filled vibration isolator according to the present invention is applied to an engine mount A for an automobile. The engine mount A includes an automobile engine and a transmission (not shown). It is interposed between the power plant) and the vehicle body to support those static loads and absorb or attenuate vibrations from the power plant to suppress transmission to the vehicle body.

  Moreover, the engine mount A of Embodiment 1 supports the substantially columnar inner metal fitting 1 (1st connection metal fitting) attached to a power plant via the bracket etc. which are not shown in figure, and this from the downward direction via the rubber elastic body 2. FIG. A pair of leg portions 30 each having a cylindrical outer metal fitting 3 (second connecting metal fitting) and welded to the front and rear sides of the vehicle on the lower outer periphery of the outer metal fitting 3 (only one is shown in the figure). By this, it is fixed to a vehicle body side frame or the like.

  The inner metal fitting 1 has a thick collar portion 10 in the middle portion in the column axis Z direction, a tapered portion 11 narrowed downward on the lower side, and a shaft portion 12 on the upper side, Each is formed. In the illustrated example, stopper rubber layers 13 and 14 are provided on the upper surface and the outer peripheral surface of the collar portion 10 so as to cooperate with a stopper fitting 6 described later. Further, a bracket on the power plant side is attached to the shaft portion 12, and a bolt for fastening it is screwed into the bolt hole 12a.

  In the example shown in the figure, the axis Z extends in the direction of inputting the static load of the power plant (main load input direction), and extends further downward from the lower end of the bolt hole 12a of the inner metal fitting 1 along the axis Z. In addition, a vertical hole 15 is drilled. The vertical hole 15 is open at the lower end of the inner metal fitting 1 and is used for enclosing a liquid in a liquid chamber F described later. After the liquid is sealed, the vertical hole 15 is sealed with a steel ball 16.

  The rubber elastic body 2 is vulcanized and bonded at its upper portion to cover the tapered portion 11 on the lower side of the inner metal fitting 1, and an umbrella-shaped main spring portion 20 extending obliquely downward while expanding radially therefrom. It consists of a cylindrical extension portion 21 that extends downward continuously from the lower end of the spring portion 20, and is connected to the inner periphery of the outer metal fitting 3 at this extension portion 21. That is, in the illustrated example, the outer metal fitting 3 has a double structure composed of an inner cylinder 31 and an outer cylinder 32, and the inner cylinder 31 is embedded and integrated in the extending portion 21 of the rubber elastic body 2. In addition, the outer peripheral surface of the extending portion 21 is bonded and fixed to the inner peripheral surface of the outer cylinder 32.

  In addition, the inner circumference of the extending portion 21 of the rubber elastic body 2 is expanded on the lower side to form an annular stepped portion, and the orifice disc 4 is fitted from below as a receiving portion, A rubber diaphragm 5 is attached so as to cover the orifice plate 4 from below. A reinforcing metal fitting is embedded in the outer peripheral portion of the diaphragm 5 and is caulked from below by a flange formed at the lower end of the inner cylinder 31 of the outer metal fitting 3.

  Then, the lower end opening of the outer metal fitting 3 is closed by the diaphragm 5, and the liquid chamber F is formed. The liquid chamber F is vertically divided by an orifice panel 4 (partition member), and the upper side thereof, that is, one side in the main load input direction is the pressure receiving chamber f1 (main liquid chamber), and the lower side is the equilibrium chamber f2 ( 1st sub-liquid chamber). Although the structure of the orifice board 4 will be described in detail later, in the example shown in the drawing, a first orifice passage P1 having a double upper and lower structure is formed on the outer periphery thereof, and the pressure receiving chamber f1 and the equilibrium chamber f2 are communicated with each other.

  In addition, an intermediate liquid chamber f3 (second sub-liquid chamber) is formed on the inner peripheral side of the orifice plate 4 and is partitioned from the pressure receiving chamber f1 by a membrane 42 (elastic film member). An annular second orifice passage P2 is formed so as to surround the intermediate liquid chamber f3, and the intermediate liquid chamber f3 communicates with the equilibrium chamber f2. As the liquid flows between the equilibrium chamber f2, the pressure receiving chamber f1 and the intermediate liquid chamber f3 through the first and second orifice passages P1 and P2, vibrations from the power train are effectively absorbed and attenuated. The

  On the other hand, an inverted cup-shaped stopper fitting 6 is disposed on the top of the mount A so as to cover the main spring portion 20 of the rubber elastic body 2 and the lower end thereof is fixed by caulking to the upper end of the outer fitting 3. ing. The peripheral wall of the stopper fitting 6 forms a stopper mechanism in the front-rear direction of the vehicle in cooperation with the stopper rubber layer 14 of the flange portion 10 of the inner fitting 1. Similarly, the upper end wall of the stopper fitting 6 is the stopper rubber layer 13. The stopper mechanism in the vertical direction is configured in cooperation with the above.

  FIG. 1 shows a state in which the static load of the power plant is not acting on the mount A, and the gap between the stopper rubber layer 13 and the upper end wall of the stopper fitting 6 is small, but the engine mount A is attached to the automobile. In the 1G state where the power plant is supported and the static load is applied, the rubber elastic body 2 is bent and the inner metal fitting 1 is displaced downward, so that the gap is enlarged.

-Orifice board structure-
Next, the structure of the orifice plate 4 will be described in detail. The orifice plate 4 of this embodiment includes a donut-shaped outer member 40 fitted into the outer metal fitting 3, as shown in an enlarged view in FIG. The inner member 41 is fitted into the inner member 41 to form a thick disk as a whole. The combined orifice plate body is formed with a recess opening toward the upper pressure receiving chamber f1, and the upper end opening of the recess is covered with the membrane 42 to form the intermediate liquid chamber f3. ing.

  The outer member 40 is made of, for example, metal (may be made of resin), and the flange portions 40b to 40d protrude from the upper end, the lower end, and the intermediate portion thereof on the outer peripheral surface of the cylindrical main body portion 40a, and between them. Two upper and lower annular grooves 40e and 40f are formed so as to open outward. 2, one end of the upper annular groove 40e communicates with a long hole 40g penetrating the flange portion 40b, while the other end of the annular groove 40e is connected to the lower annular portion by the inclined groove portion 40h. It communicates with one end of the groove 40f. Further, the other end of the lower annular groove 40f communicates with a narrow slot 40i that penetrates a portion closer to the inner periphery of the flange portion 40d.

  On the other hand, the inner member 41 of the orifice plate 4 is a recess having a circular cross section which is provided with a cylindrical wall portion 41b having a smaller diameter on the upper surface of a substantially disc-shaped bottom plate portion 41a and which opens upward inward. 41c is formed, while a flange 41d protrudes from the upper end of the outer peripheral surface of the cylindrical wall portion 41b, and opens to the outside over almost the entire periphery between the portion near the outer periphery of the bottom plate portion 41a. An annular groove 41e is formed. One end of the annular groove 41e communicates with a notch 41f provided in the flange 41d in the circumferential portion shown in the front of FIG. 2, and opens upward, while the other end of the annular groove 41e is the bottom plate portion 41a. It communicates with a notch 41g provided at the bottom and opens downward.

  Then, as shown in the figure, the inner member 41 is fitted into the outer member 40 from below so that the lower surface of the bottom plate portion 41a of the inner member 41 is substantially flush with the lower surface of the flange 40d at the lower end of the outer member 40. After the assembly, when these are fitted into the outer metal fitting 3, the openings of the annular grooves 40e, 40f of the outer member 40 are covered with the extending portion 21 of the rubber elastic body 2 as shown in FIG. A spiral first orifice passage P1 is formed.

  The upper end of the first orifice passage P1 thus formed opens toward the pressure receiving chamber f1 on the upper surface of the flange portion 40b of the outer member 40 of the orifice panel 4 (the long hole 40g shown in FIG. 1), while the lower end is An opening is formed facing the equilibration chamber f2 at a portion near the inner periphery of the lower surface of the flange portion 40d (the long hole 40i). The first orifice passage P1 circulates around the outer periphery of the orifice plate 4 twice, and is considerably long. Therefore, when the liquid flows between the pressure receiving chamber f1 and the equilibrium chamber f2 through this, the first orifice passage P1 is considerably low. The liquid resonance occurs at a set frequency (for example, about 5 Hz).

  Similarly, the second orifice passage P2 of the inner member 41 also opens at the upper end facing the intermediate liquid chamber f3 on the upper surface of the flange 41d (notch portion 41f), while the lower end is the bottom plate portion 41a of the inner member 41. The lower surface is opened facing the equilibrium chamber f2 (notch portion 41g), and the length of the second orifice passage P2 is shorter than that of the first orifice passage P1, so that the equilibrium chamber f2 and the intermediate liquid are passed through this. When the liquid flows between the chambers f3, resonance of the liquid occurs at a second set frequency (for example, about 20 to 25 Hz) higher than the first set frequency.

  That is, the mount A of this embodiment is basically a double-orifice type having two first and second orifice passages P1, P2, one of which is in a relatively low frequency range, The other is tuned to a relatively high frequency range. In addition, in this embodiment, a communication hole 42a having a predetermined size is provided in the membrane 42 that divides the pressure receiving chamber f1 and the intermediate liquid chamber f3, and substantially in a frequency region where the flow rate of the liquid is relatively low. Both chambers f1, f3 are communicated with each other.

  Specifically, the membrane 42 is formed into a disk shape having a diameter of about 30 to 60 mm and a thickness of about 1.5 to 3.0 mm using various rubber materials such as NR, NR / BR, IIR and silicone rubber. The rubber hardness is set to approximately 40 to 80 degrees (JIS K6253 A). The outer peripheral edge of the membrane 42 is bonded to the opening peripheral edge of the upper end of the recess of the orifice board body (outer member 40 and inner member 41), and preferably has a circular cross section so as to penetrate the vicinity of the center. The hole 42a is formed, and the diameter is set to about 4.0 mm as an example.

  As will be described in detail below, the larger the communication hole 42a and the higher the hardness of the rubber of the membrane 42, the easier the liquid flows through the communication hole 42a. Also, if the membrane 42 itself is large, the size (cross-sectional area) of the communication hole 42a does not vary so much when the membrane 42 is elastically deformed due to fluctuations in the fluid pressure in the pressure receiving chamber f1 and the intermediate liquid chamber f3. The liquid flow state through the communication hole 42a is stabilized. In this regard, it is advantageous to form the communication hole 42 a at the approximate center of the membrane 42.

-Damping action by the first and second orifice passages-
The damping action by the first and second orifice passages P1, P2 having such a configuration will be described in detail below. First, the structure of the engine mount A is schematically shown. As shown in FIG. 3, the pressure receiving chamber f1 is communicated with the equilibrium chamber f2 by the first orifice passage P1, and the equilibrium chamber f2 is intermediated by the second orifice passage P2. It communicates with the liquid chamber f3. A communication hole 42a is formed in the membrane 42 between the intermediate liquid chamber f3 and the pressure receiving chamber f1. The first orifice passage P1 is tuned to a frequency of, for example, about 5 Hz lower than the shake vibration, and the second orifice passage P2 is tuned to, for example, about 20 to 25 Hz in accordance with the idle vibration.

  If the communication hole 42a of the membrane 42 is not provided, the structure is the same as that of a conventionally known double orifice type (see, for example, Patent Document 1). The frequency characteristics of the action (hereinafter also simply referred to as attenuation characteristics) are simply around the respective resonance frequencies (in the example shown in the figure) by the resonance of the liquid in the two orifice passages P1 and P2, as indicated by the one-dot chain line in FIG. Attenuation peaks appear independently at 5 Hz and 23 Hz).

  On the other hand, if there is no membrane 42, it can be considered that the pressure receiving chamber f1 and the equilibrium chamber f2 are communicated with each other through a virtual one orifice passage including the first and second orifice passages P1 and P2. . The attenuation characteristic due to the resonance of the liquid in the virtual orifice passage is as shown by a virtual line (two-dotted line) in FIG. 4, and the frequency range between the peaks of the first and second orifice passages P1 and P2 (in the figure). A peak of attenuation higher than any of them appears at about 15-20 Hz.

  When the communication hole 42a is provided in the membrane 42 as in this embodiment, as shown by the solid line and the broken line in the figure, it is as if the two characteristics are combined, and the size of the communication hole 42a ( Depending on the cross-sectional area, intermediate characteristics between the two are exhibited. That is, the graph indicated by the solid line a in the same figure is the case where the diameter of the communication hole 42a is 4.0 mm as in this embodiment, the broken line b1 is 6.0 mm in diameter, while the broken line b2 is 2.5 mm in diameter. Each case is shown.

  From the same figure, it can be seen that, as the overall trend, the smaller the diameter of the communication hole 42a, the closer to the characteristics of the double orifice type, and the larger the diameter, the closer to the characteristics of the virtual orifice passage. Further, when the graphs a and b1 are compared, the attenuation action on the low frequency side (10 to 20 Hz in the example in the figure) increases as the hole diameter increases, whereas the attenuation action decreases on the high frequency side (20 Hz or more). I understand that.

  More specifically, when a relatively low frequency vibration of approximately less than 15 Hz is input to the mount A having the characteristics as shown in the graphs a and b1, the volume of the pressure receiving chamber f1 is periodically changed, and FIG. As shown by a solid line arrow, the liquid flows between the equilibrium chamber f2 through the first orifice passage P1, and also through the intermediate liquid chamber f3 and the second orifice passage P2 as shown by the broken line arrow. Liquid flows to and from the equilibrium chamber f2. That is, since the flow velocity of the liquid generated by the low frequency vibration input is relatively low, this liquid flows through the communication hole 42a without any problem, and the equilibrium chamber f2 and the intermediate liquid chamber f3 are substantially communicated. It comes to be.

  In this state, since the liquid flows even through the shorter second orifice passage P2, the damping effect due to the resonance of the liquid in the first orifice passage P1 is reduced, but from there to the high-frequency side, the above-described virtual orifice passage is used. A high damping action is obtained, and this damping action becomes higher as the frequency increases. In the illustrated solid line graph a, the damping action is increased up to about 20 Hz, and in the broken line graph b1 up to about 15 Hz, the damping action is increased as the frequency increases.

  However, as the frequency of the input vibration increases, the liquid gradually becomes difficult to flow through the first orifice passage P1 (so-called clogging), and the communication hole 42a of the membrane 42 also becomes difficult to flow. The solid line graph a starts from about 10 Hz, and the broken line graph b1 starts from about 13 Hz, and the high attenuation effect due to the virtual orifice passage is gradually lost. Each of the graphs a and b1 is obtained from the virtual line graph. Go away.

  In the example shown in the figure, in the relatively high frequency range exceeding 20 Hz, the communication hole 42a of the membrane 42 is substantially closed, and the liquid flow is balanced mainly through the second orifice passage P2. Since it occurs only between the chamber f2 and the intermediate liquid chamber f3, it is considered that the damping action (indicated by a one-dot chain line) by the second orifice passage P2 is dominant.

  In the example shown in the figure, both of the graphs a and b1 show lower attenuation than the one-dot chain line graph in a frequency region of 20 Hz or higher, and in particular, the large broken line graph b1 of the communication hole 42a has lower attenuation. It has become. This is because the liquid flow through the communication hole 42a does not completely disappear even in a relatively high frequency range, and this reduces the damping action by the second orifice passage P2.

  Therefore, according to the engine mount A (anti-vibration device) according to this embodiment, when the frequency of vibration to be input is relatively low, the interaction between the first and second orifice passages P1 and P2 causes a virtual Thus, a high damping action due to the resonance of the liquid in one orifice passage is obtained, and as the frequency of the vibration increases, the damping action gradually shifts to the damping action by the second orifice passage P2. A high damping effect can be obtained over a wide frequency range.

  Therefore, if the first orifice passage P1 is tuned to a predetermined frequency (for example, 5 Hz) lower than the shake vibration and the second orifice passage P2 is tuned to about 20 to 25 Hz in accordance with idle vibration as in this embodiment, As shown by the solid line “a” or the broken line “b1” in FIG. 4, a sufficient vibration damping action can be obtained over a wide frequency range covering from so-called shake vibration to idle vibration.

  In addition, since the first and second orifice passages P1 and P2 function over a wide frequency range, a so-called dynamic spring jump does not occur in this frequency range, and as a result, shake or While absorbing and attenuating idle vibrations and the like, vibrations in the intermediate frequency range can also be effectively absorbed and attenuated to improve the riding comfort of the vehicle.

  Specifically, FIG. 5 shows a vibration input having a relatively large amplitude correlated with the ride comfort of the vehicle such as shake vibration (in the example shown in the figure, a preload of 963 N is applied and an amplitude of ± 0.5 mm is applied. The result of examining the dynamic spring and the damping of the mount A of this embodiment for the vibration) is shown in comparison with a conventional single orifice type liquid ring mount.

  The solid line graph in FIG. 4B is the same as the solid line graph a in FIG. 4 although the scale is different. Compared with the conventional liquid ring mount shown by the broken line in the figure, the so-called shake vibration region (around 10 Hz) However, the required attenuation can be ensured, and a high attenuation effect is obtained over a very wide range from about 30 to 40 Hz. As a result, not only shake vibration but also vehicle body vibration due to pitching or the like can be sufficiently suppressed, and riding comfort is improved.

  In addition, as shown by the solid line graph in FIG. 6A, the jump of the dynamic spring (shown by the broken line in the figure) does not occur over a wide frequency range of 10 to 30 Hz, and the idle vibration is not generated. There is no risk of adverse effects on absorption. In addition, for vibration input with a relatively large amplitude, if the dynamic spring falls as shown by the broken line graph, there is a concern that the whole powertrain may become wobbled, but the solid line graph has no drop. There is no such worry.

  On the other hand, FIG. 6 shows the characteristics when the vibration is applied with a relatively small amplitude (± 0.05 mm) corresponding to the idle vibration. As shown in FIG. In this example, the bottom of the dynamic spring is seen at 15 to 25 Hz), so it can be seen that the mount A of this embodiment can effectively absorb idle vibration and the like and sufficiently suppress the transmission of vibration to the vehicle body.

  Moreover, in the wide frequency range, a very high attenuation is obtained as shown by the solid line graph in FIG. (B), which not only effectively absorbs idle vibrations as described above, but also Attenuating effect can also be expected.

-Modification-
7 to 9 show modifications of the first embodiment. The mount A of this modification is different from the above-described embodiment only in the specific structure of the orifice board 4.

  First, in the modification 1 shown in FIG. 7, the orifice disk 4 is comprised by the substantially disc-shaped main body member 45 and the cover member 46 assembled | attached to this. The main body member 45 has a structure as if the inner member 41 in the embodiment is removed from the inner member 41 and combined with the outer member 40, for example, integrally formed with a metal material (or a resin material).

  On the other hand, the lid member 46 has a structure in which the membrane 42 is attached so as to close the opening of the flange 41d removed from the inner member 41, and the lid member 46 is disposed above the main body member 45 as shown in the figure. As a result, the second orifice passage P2 and the intermediate liquid chamber f3 are formed. In the illustrated example, the lid member 46 is also a molded product of a metal material (or resin material), but the lid member 46 may be formed by sheet metal processing.

  Moreover, in modification examples 2 and 3 shown in FIGS. 8 and 9, respectively, the entire lid member 46 is formed of a rubber material, and a portion closer to the center functions as a membrane, and a communication hole 46a is formed at the center. It is. In FIG. 8, a metal (or resin) ring member 46 b is provided on the outer peripheral edge of the lid member 46, and the lid member 46 is fitted into the main body member 45. In FIG. 9, a separate locking member 47 is inserted later, and a portion near the outer periphery of the lid member 46 is sandwiched between the locking member 47 and the main body member 40.

(Embodiment 2 and its modifications)
Next, FIG. 10 shows a longitudinal sectional view of an engine mount A ′ according to the second embodiment of the present invention and its modification. Since this engine mount A ′ is generally structured such that the mount A of the first embodiment is inverted, members having the same function are given the same reference numerals even if their shapes are different. Therefore, the description is omitted.

  In the mount A ′ shown in FIG. 5A, the inner metal fitting 1 is connected to the vehicle body side (support side), while the cast outer metal fitting 3 is connected to the power train side (supported side). The main spring portion 20 of the rubber elastic body 2 that connects them has a bowl shape that expands in diameter upward. Then, the orifice plate 4 and the diaphragm 5 are assembled to the main spring portion 20 from above, thereby dividing the liquid chamber F, that is, the lower pressure receiving chamber f1 and the upper equilibrium chamber f2.

  The structure of the orifice board 4 is the same as that of the first embodiment described above with reference to FIG. 2, and is arranged upside down. That is, the orifice platen 4 is constituted by an outer member 40, an inner member 41 and a membrane 42. A first orifice passage P1 having a double upper and lower structure is provided on the outer periphery thereof, and an intermediate liquid chamber f3 is provided on the inner peripheral side thereof. An annular second orifice passage P2 is formed so as to surround it.

  The first orifice passage P1 communicates the pressure receiving chamber f1 and the equilibrium chamber f2, and the second orifice passage P2 communicates the equilibrium chamber f2 and the intermediate liquid chamber f3. A communication hole 42a is formed in the membrane 42 between the pressure receiving chamber f1 and the intermediate liquid chamber f3, and the pressure receiving chamber f1 and the intermediate liquid chamber f3 are substantially communicated with respect to low frequency vibration input. ing.

  The engine mount A ′ according to the second embodiment also obtains the same effects as those of the first embodiment and its modifications, and absorbs vibrations in a wide frequency range covering from shake vibration to idle vibration. Attenuating can improve the ride comfort of the vehicle.

  In the modification shown in FIG. 2B, the orifice plate 4 is constituted by a disc-shaped main body member 48 and an annular member 49 combined therewith, and a first orifice passage P1 having a double inner / outer structure is formed therein. In addition, the intermediate liquid chamber f3 is partitioned by the membrane 42.

  Further, a metal (or resin) ring member 51 is provided on the outer peripheral edge of the diaphragm 5 so as to be fitted into the outer metal fitting 3, and a second orifice passage P2 is formed inside the ring member 51. ing.

  The modified example shown in FIG. 7C is obtained by using the orifice plate 4 having the same structure as that of the modified example 3 of the first embodiment (see FIG. 9) in the mount A ′ of the second embodiment. is there.

-Other embodiments-
The configuration of the vibration isolator according to the present invention is not limited to the above-described first and second embodiments and modifications thereof, and includes various other configurations. For example, in each of the above-described embodiments, the second orifice passage P2 of the first and second orifice passages P1 and P2 is formed to be relatively long. In short, the second orifice passage P2 only needs to be tuned to the higher frequency side.

  In addition, the size of the communication holes 42a and 46a formed in the membrane 42 and the lid member 46 is important as it affects the characteristics of the mounts A and A 'as described above. In consideration of the rubber hardness and the like, it should be set by experiment according to the characteristics required for the mount. For example, when the thickness of the membrane 42 is about 1.0 to 5.0 mm, the communication hole It is considered that the diameters of 42a and 46a may be set in the range of 2.0 to 10.0 mm. From the example of FIG. 4, it can be said that the range of about 3.0 to 6.0 mm is particularly preferable. The communication holes 42a and 46a are not necessarily provided at the center of the membrane 42 or the like.

  In each of the above-described embodiments, the pressure receiving chamber f1 and the equilibrium chamber f2 are partitioned by the orifice plate 4, and the intermediate liquid chamber f3 is provided in the orifice plate 4. However, the present invention is not limited to this, and both chambers f1 are provided. , F2 may be provided separately from the orifice members P1 and P2 and the intermediate liquid chamber f3.

  Further, in each of the above-described embodiments, the intermediate liquid chamber f3 is provided on the pressure receiving chamber f1 side of the orifice plate 4, and the chambers f1, f3 are partitioned by the membrane 42 and the like, and the communication holes 42a, However, the present invention is not limited to this, and the intermediate liquid chamber f3 may be provided on the equilibrium chamber f2 side, and the chambers f2 and f3 may be partitioned by the membrane 42 or the like.

  Furthermore, in each of the above-described embodiments, the vibration isolator of the present invention is applied to the so-called vertical engine mounts A and A ′. It can also be applied to suspension bushes as well as engine mounts, and it is considered that it can also be applied to vibration isolation devices other than those for automobiles.

  As described above, since the vibration isolator according to the present invention can obtain a high damping action over a wide frequency range by the interaction of the two orifice passages, it can be applied to an engine mount for automobiles. It is extremely effective in improving ride comfort.

It is a perspective view which shows the structure of the engine mount which concerns on Embodiment 1 in part and a cross section. It is a disassembled perspective view which shows the structure of the same orifice board. It is a schematic diagram of the mount for demonstrating the interaction of an orifice channel | path. It is a graph which shows the change of the attenuation | damping property by changing the magnitude | size of the communicating hole of a membrane. It is a graph which shows the dynamic spring and damping | damping characteristic when an amplitude is relatively large. FIG. 6 is a diagram corresponding to FIG. 5 when the amplitude is relatively small. FIG. 6 is a view corresponding to FIG. 1 according to a first modification of the first embodiment. FIG. 10 is a view corresponding to FIG. 1 according to the second modification. FIG. 10 is a view corresponding to FIG. It is a longitudinal cross-sectional view which shows the structure of the mount concerning Embodiment 2 and its modification.

A, A 'engine mount (liquid-filled vibration isolator)
F liquid chamber f1 pressure receiving chamber (main liquid chamber)
f2 Equilibrium chamber (first auxiliary liquid chamber)
f3 Intermediate liquid chamber (second auxiliary liquid chamber)
P1 First orifice passage P2 Second orifice passage Z Axis (main vibration input direction)
1 Inner bracket (connection bracket)
2 Rubber elastic body 3 Outer metal fitting (connection metal fitting)
4 Orifice panel (partition member)
42 Membrane (elastic membrane member)
42a Communication hole 46 Lid member (elastic film member)
46a Communication hole

Claims (4)

A first coupling fitting on the supported side, a second coupling fitting on the support side coupled to the rubber elastic body, and a main coupling formed between the metal fittings so that the volume changes with deformation of the rubber elastic body. A liquid-filled vibration isolator comprising a liquid chamber and a first sub liquid chamber communicated with the main liquid chamber by a first orifice passage,
A second sub liquid chamber communicated with the first sub liquid chamber by a second orifice passage, and the second orifice passage is at least one of shorter or larger in cross-sectional area than the first orifice passage; And
The main liquid chamber and the second sub liquid chamber are partitioned by an elastic film member, and a communication hole having a predetermined size is formed in the elastic film member so as to communicate the two liquid chambers. A liquid-filled vibration isolator characterized by   The partition member that partitions the main liquid chamber and the first sub liquid chamber is provided, and the second sub liquid chamber and the first and second orifice passages are formed in the partition member. Liquid filled vibration isolator. One of the first and second connection fittings is a columnar shape extending in the main load input direction, and the other is a cylindrical shape spaced apart on the outer peripheral side of the one connection fitting,
The partition member is fitted inside the other coupling fitting, and partitions the main liquid chamber on one side of the main load input direction and the first sub liquid chamber on the other side,
The partition member is formed with a concave portion that opens to face the main liquid chamber. The opening is covered with the elastic film member to form a second sub liquid chamber, and at the substantially center of the elastic film member. The liquid-filled vibration isolator according to claim 2, wherein a communication hole is formed.   The liquid-filled vibration isolating apparatus according to any one of claims 1 to 3, wherein the elastic membrane member has a thickness of 1.0 to 5.0 mm and a communication hole diameter of 2.0 to 10.0 mm. apparatus.

Images