JP2010203547A - Liquid-filled vibration isolator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a high damping effect over a wide frequency range like never before by exercising ingenuity to the structure of liquid chambers or orifice channels in a liquid-filled vibration isolator. <P>SOLUTION: The liquid-filled vibration isolator includes the first orifice channel P1 providing communication between a pressure receiving chamber f1 and a balancing chamber f2 and a second orifice channel P2 providing communication between the pressure receiving chamber f1 and an intermediate liquid chamber f3. A communicating hole 42a of a predetermined size is formed in a member 42 separating the balancing chamber f2 and the intermediate liquid chamber f3. A movable plate 43 is arranged in an inner member 41 of an orifice disk 4 separating the pressure receiving chamber f1 and the intermediate liquid chamber f3. A high damping effect is obtained with an imaginary orifice channel combined from the two orifice channels P1 and P2. As the vibration frequency increases, a gradual transition is made to the damping characteristic of the second orifice channel P2 only. A sufficient damping effect can be therefore obtained over a wide frequency range like never before. Liquid pressure fluctuations of the pressure receiving chamber f1, etc. are absorbed by the movable plate 43 and a so-called jump of the dynamic stiffness is solved. <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 communicating the main liquid chamber and the first sub liquid chamber is subjected to shake vibration around 10 Hz, and the second orifice passage communicating the main liquid chamber and the second sub liquid chamber is 20 to 30 Hz. Each is tuned to the nearby idle vibration.
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. .

  Then, as in the conventional example (Patent Documents 1 and 2) described above, the second sub-channel communicated with either one of the main liquid chamber or the first sub-liquid chamber by a second orifice passage. A liquid chamber, and when the second orifice passage is at least one shorter than the first orifice passage or larger in cross-sectional area, the other of the main liquid chamber and the first sub liquid chamber The liquid chamber and the second sub-liquid chamber are partitioned by an elastic film member, and the elastic film member has a communication hole of a predetermined size so as to communicate the other liquid chamber and the second sub-liquid chamber. Form. Furthermore, a movable plate is disposed on the partition wall between the one liquid chamber and the second sub-liquid chamber so as to move by receiving the liquid pressure of these liquid chambers and absorb the fluctuation of the liquid pressure. ing.

  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 main liquid chamber and the first sub liquid chamber through the second orifice passage and the second sub liquid chamber. This is because the flow rate of the liquid generated by the low-frequency vibration input is relatively low. At this time, the two liquid chambers partitioned by the elastic film member are substantially communicated with each other through the communication hole. It 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 communication hole of the elastic membrane member also becomes difficult to flow. The damping action by the passage is gradually lost, and the damping action by 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. As shown by the solid line and the broken line in FIG. 4, 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. A high damping effect that has not been obtained 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, according to the above configuration, the movable plate is disposed on the partition wall between the liquid chamber of either one of the main liquid chamber or the first sub liquid chamber and the second sub liquid chamber. The movement of the movable plate absorbs fluctuations in the hydraulic pressure in the one liquid chamber or the second auxiliary liquid chamber, so that a so-called dynamic spring jump does not occur for a vibration input having a relatively small amplitude. Can be.

  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 that partitions the main liquid chamber and the first sub liquid chamber is provided, the first and second orifice passages are formed in the partition member, the movable plate is also disposed, The partition member is formed with a recess that faces the first sub-liquid chamber, and the opening is covered with the elastic film member to form a second sub-liquid chamber (Claim 2).

  In this way, the first and second orifice passages and the second auxiliary liquid chamber are formed in the partition member, and the movable plate is disposed, thereby simplifying the structure. In addition, providing the second sub liquid chamber on the first sub liquid chamber side of the partition member and partitioning the sub liquid chambers by the elastic film member is effective in preventing cavitation. That is, if the main liquid chamber and the second sub liquid chamber are partitioned by the elastic film member, the liquid flows between the main liquid chamber and the second sub liquid chamber through the communication hole of the elastic film member. This is because a strong turbulent flow is generated when the gas is discharged, and there is a possibility that bubbles are generated in the main liquid chamber in the vicinity of the communication hole.

  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 chamber is defined on the other side. And while forming a communicating hole in the approximate center of the elastic membrane member covering the opening of the recess of the partition member, the bottom wall of the recess serves as a partition wall that divides the main liquid chamber and the second sub liquid chamber A movable plate may be disposed here (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 damping action inherent in the present invention as described above. Specifically, the larger the cross-sectional area of the communication hole, the virtual orifice passage. On the other hand, 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.

  Further, for vibration input with a relatively small amplitude, fluctuations in the hydraulic pressure caused by this can be absorbed by the movable plate, and so-called dynamic spring jumps can be eliminated.

  Therefore, for example, when used as an engine mount of an automobile, vibrations of the engine and the like can be effectively absorbed and attenuated over a wide frequency range such as from shake to idle vibration, and the ride quality of the vehicle can be greatly 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.

  Further, an intermediate liquid chamber f3 (second sub liquid chamber) is formed on the lower side on the inner peripheral side of the orifice plate 4, and the membrane 42 (elastic film member) is partitioned from the equilibrium chamber f2. On the other hand, a movable plate 43 is accommodated in a partition wall that divides the intermediate liquid chamber f3 from the upper pressure receiving chamber f1, and an annular second orifice passage P2 is formed surrounding the accommodation chamber of the movable plate 43. Thus, the intermediate liquid chamber f3 is communicated with the pressure receiving chamber f1.

  As will be described later, the vibration from the power train is effective when the liquid flows between the pressure receiving chamber f1, the equilibrium chamber f2, and the intermediate liquid chamber f3 through the first and second orifice passages P1 and P2. Are absorbed and attenuated. Further, the movement of the movable plate 43 absorbs the fluid pressure fluctuations in the pressure receiving chamber f1 and the intermediate fluid chamber f3.

  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 that opens toward the lower equilibrium chamber f2, and the lower end opening of the recess is covered with the membrane 42 to form an 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.

  Further, the inner member 41 of the orifice board 4 has a cross-section in which a cylindrical wall portion 41b having a smaller diameter is erected on the upper surface of a substantially disc-shaped bottom plate portion 41a and opens upward inward. A circular recess 41c is formed. The movable plate 43 is accommodated in the recess 41c, and the lid member 44 is attached so as to cover the upper portion of the recess 41c. And in the site | part near the center of the bottom plate part 41a of the inner member 41 which is a floor part of this accommodating chamber, it attaches and shows only the code | symbol in FIG. On the other hand, the through-holes 44a, 44a,... Are also formed in the lid member 44 that becomes the ceiling portion of the storage chamber.

  Furthermore, a flange 41d protrudes from the upper end of the outer peripheral surface of the cylindrical wall 41b of the inner member 41, and opens to the outside over the entire circumference between the portion near the outer periphery of the bottom plate 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, the inner member 41 having the movable plate 43 and the lid member 44 attached thereto is fitted into the outer member 40 from above, and the upper surface of the flange portion 41d of the inner member 41 is the upper flange portion of the outer member 40 as shown in the figure. After assembling them so as to be substantially flush with the upper surface of 40b, if these are fitted into the outer metal fitting 3, the openings of the annular grooves 40e, 40f of the outer member 40 are extended from the rubber elastic body 2, as shown in FIG. A spiral first orifice passage P1 is formed which is covered by the portion 21 and is doubled up and down.

  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 pressure receiving chamber f1 on the upper surface of the flange 41d of the inner member 41 (notch portion 41f also shown in FIG. 1), while the lower end is the bottom plate. The lower surface of the portion 41a opens toward the intermediate liquid chamber f3 (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 pressure receiving chamber f1 is passed through this. When the liquid flows between the intermediate liquid chambers f3, liquid resonance 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 equilibrium chamber f2 and the intermediate liquid chamber f3, and substantially in a frequency region where the flow rate of the liquid is relatively low. Both chambers f2, 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 peripheral edge of the opening at the lower end of the recess of the orifice plate 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 equilibrium chamber f2 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, schematically showing the structure of the engine mount A, as shown in FIG. 3, the pressure receiving chamber f1 is communicated with the equilibrium chamber f2 and the intermediate liquid chamber f3 by the first and second orifice passages P1 and P2, respectively. A communication hole 42a is formed in the membrane 42 between the two chambers f2, f3.

  The first orifice passage P1 is tuned to a frequency of, for example, about 5 Hz, which is lower than the shake vibration, and the second orifice passage P2 is tuned to, for example, about 20-25 Hz in accordance with idle vibration. Further, since the movable plate 43 is provided in parallel with the second orifice passage P2, the vibration damping action by the second orifice passage P2 is lowered depending on the frequency.

  For convenience of explanation, first, the effect of the two orifice passages P1 and P2 will be described, ignoring the influence of the movable plate 43. First, assuming that the communication hole 42a of the membrane 42 is not provided, since this is a general double orifice type structure, the frequency characteristic of the damping action of the mount A (hereinafter, also simply referred to as a damping characteristic). 4), as indicated by the one-dot chain line in FIG. 4, due to the resonance of the liquid in the two orifice passages P1 and P2, the peak of attenuation is independently generated near the respective resonance frequencies (5 Hz and 23 Hz in the example in the figure). Appears.

  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 first orifice passage P1 and the equilibrium chamber f2 through the first orifice passage P1, and also through the second orifice passage P2 and the intermediate liquid chamber f3 as shown by a 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 increases with increasing frequency up to about 20 Hz, and in the broken line graph b1 up to about 15 Hz.

  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 blocked, and the flow of the liquid mainly takes place through the second orifice passage P2 and the pressure receiving chamber f1. And the intermediate liquid chamber f3, the damping action (indicated by the one-dot chain line) by the second orifice passage P2 is considered to be dominant.

  That is, when the frequency of the input vibration is relatively low due to the interaction between the first and second orifice passages P1 and P2, a damping action by the virtual one orifice passage is obtained, and the frequency of the vibration is obtained. As the value becomes higher, it gradually shifts to the damping action of the second orifice passage P2 alone, and in the example shown in the figure, a high damping action can be obtained over a wide frequency range of approximately 10 to 30 Hz.

  In the example shown in the figure, both the graphs a and b1 show somewhat lower attenuation than the one-dot chain line graph in the frequency range of 20 Hz or higher. Particularly, the large broken line graph b1 of the communication hole 42a is attenuated. It is low. 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.

−Vibration absorption by movable plate−
In addition to the above-described damping action by the two orifice passages P1 and P2, in this embodiment, the movable plate 43 is provided on the inner member 41 (partition wall) of the orifice plate 4 that partitions the pressure receiving chamber f1 and the intermediate liquid chamber f3. The fluid pressure fluctuations of the pressure receiving chamber f1 and the intermediate liquid chamber f3 can be absorbed by the movement.

  That is, as described above with reference to FIG. 2, the inner member 41 of the orifice board 4 is formed with a housing chamber for the movable plate 43, and is viewed from above through the through holes 44 a, 44 a,. While the fluid pressure in the pressure receiving chamber f1 acts, the fluid pressure in the intermediate fluid chamber f3 acts from below through the through holes 41h, 41h,... In the bottom plate portion 41a, and the fluid pressures in the fluid chambers f1, f3 fluctuate. In other words, the movable plate 43 moves up and down.

  Therefore, for example, when vibration with a relatively small amplitude such as idle vibration is input, the hydraulic pressure fluctuation in the pressure receiving chamber f1 is absorbed by the vertical movement of the movable plate 43, and so-called jump of the dynamic spring is eliminated. can do. However, since the moving amount of the movable plate 43 cannot be increased so as to sufficiently secure the damping action by the orifice passages P1 and P2, the action of the movable plate 43 is limited when the amplitude of the input vibration is large. Become.

  As described above, according to the engine mount A (anti-vibration device) according to this embodiment, the first orifice passage P1 is tuned to a predetermined low frequency (for example, 5 Hz), and the second orifice passage P2 is adjusted to 20 in accordance with idle vibration. By tuning to about ˜25 Hz, a sufficient vibration damping action can be obtained over a wide frequency range covering from so-called shake vibration to idle vibration by the interaction of the two orifice passages P1 and P2.

  Further, for vibration input with a relatively small amplitude such as idle vibration, for example, the fluctuation of the hydraulic pressure due to this can be absorbed by the movement of the movable plate 43, and so-called jump of the dynamic spring can be eliminated. Therefore, vibrations of the engine or the like can be effectively absorbed and attenuated over a wide frequency range such as from shake to idle vibration, and the riding comfort of the vehicle can be greatly improved.

  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.

  First, the solid line graph shown in FIG. 4B is the same as the solid line graph a in FIG. 4 although the scale is different, and the conventional type shown by the broken line in the figure due to the interaction of the two orifice passages P1 and P2. It can be seen that a high damping effect can be obtained in a much wider frequency range than the liquid ring mount. 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.

  Further, the one-dot chain line in the figure shows the case where the movable plate 43 is added as in this embodiment, and the vibration damping action by the orifice passages P1 and P2 is slightly reduced due to the influence of the movable plate 43. However, the reduction width is small, and it can be seen that a high attenuation effect can be obtained in a wide frequency range as in the solid line graph.

  On the other hand, since the orifice passages P1 and P2 function over a wide frequency range of 10 to 30 Hz as described above, as shown in the graph of the solid line and the alternate long and short dash line in FIG. There is no dynamic spring jump (shown in broken lines). In particular, in the graph indicated by the alternate long and short dash line, the rise of the dynamic spring is more gentle, due to the fact that the fluctuation of the hydraulic pressure is absorbed by the movement of the movable plate 43.

  For vibration input with such a relatively large amplitude, if the dynamic spring falls as in the conventional example (broken line graph), there is a concern that the entire powertrain may become wobbled. There is no drop in the graph and there is no such worry.

  Further, FIG. 6 shows characteristics when vibration is applied with a relatively small amplitude (± 0.05 mm) corresponding to idle vibration. For such a relatively small amplitude, the vibration is absorbed by the movement of the movable plate 43, so that the dynamic spring has a low and flat characteristic from low frequency to high frequency as shown by a dashed line in FIG. Will come to show. Therefore, it is possible to effectively absorb idle vibration or the like and suppress vibration transmission to the vehicle body.

  As shown by the solid line graph in the figure, if the movable plate 43 is not provided, the bottom of the dynamic spring is generated at about 20 Hz. This can be used to reduce idle vibration as much as possible. In some cases, the dynamic spring rises at 30 to 40 Hz or higher, and there is a concern about the adverse effects caused by this. Further, although the vibration damping action by the second orifice passage P2 is reduced by the influence of the movable plate 43 as shown in FIG. 5B, still higher damping is obtained as compared with the conventional example (shown by a broken line).

-Modification-
FIG. 7 shows a modification of the first embodiment. In this modified example, the specific structure of the orifice plate 4 is different from that of the above-described embodiment. Specifically, the orifice plate 4 includes a substantially disc-shaped main body member 45 and a circular top plate member 46 assembled thereto. The orifice board 4 is configured. The main body member 45 is formed by removing the flange portion 40b from the outer member 40 in the above embodiment and similarly removing the flange portion 41d from the inner member 41 and integrally molding them with, for example, a metal material (or a resin material). It is a structure like this.

  On the other hand, the top plate member 46 has a lid member 44 attached to the flange portion 40b removed from the outer member 40 and the flange portion 41d removed from the inner member 41, and is made of, for example, a metal material (or a resin material). The structure is as if it were integrally molded. By assembling the top plate member 46 to the main body member 45 from above as shown in the figure, the first and second orifice passages P1 and P2 and the accommodating chamber for the movable plate 43 are formed.

  The top plate member 46 may be a molded product such as die-cast, but can also be produced by sheet metal processing. Moreover, in the example of the figure, a ring member 42b made of metal (or resin) is provided on the outer peripheral edge of the membrane 42 and is fitted into the main body member 45. In this way, the membrane 42 can also be bonded.

(Embodiment 2)
FIG. 8 shows an engine mount A according to Embodiment 2 of the present invention, and this mount A is the same as the same member because the orifice plate 4 is inverted upside down in Embodiment 1 described above in terms of structure. Are denoted by the same reference numerals, and the description thereof is omitted.

  That is, in the mount A of the second embodiment, the inner member 41 is turned upside down and fitted from the lower side inside the outer member 40 constituting the orifice plate 4 of the first embodiment, and the flange portion 41d of the inner member 41 is fitted. The lower surface of the outer member 40 is assembled so as to be substantially flush with the lower surface of the flange 40d at the lower end of the outer member 40. In the combined orifice plate body, a recess is formed that faces the upper equilibrium chamber f2, and the upper end opening of the recess is covered with the membrane 42 to form an intermediate liquid chamber f3.

  In the orifice plate 4, the second orifice passage P2 does not connect the pressure receiving chamber f1 and the intermediate liquid chamber f3 as in the first embodiment, but connects the equilibrium chamber f2 and the intermediate liquid chamber f3. Further, the intermediate liquid chamber f3 is provided on the pressure receiving chamber f1 side in the orifice plate 4, and the membrane 42 is partitioned from the pressure receiving chamber f1. On the other hand, a movable plate 43 is accommodated in the inner member 41 that divides the intermediate liquid chamber f3 and the equilibrium chamber f2, and is moved in response to fluctuations in the hydraulic pressure in both the chambers f2, f3.

  Also in the engine mount A of the second embodiment, a high damping action can be obtained over a wide frequency range by the interaction of the first and second orifice passages P1 and P2 as in the first embodiment described above. A vibration having a small amplitude is effectively absorbed by the movement of the movable plate 43, and so-called jump of the dynamic spring is eliminated.

  However, if the communication hole 42a of the membrane 42 is opened facing the pressure receiving chamber f1 as in the second embodiment, the fluid pressure in the pressure receiving chamber f1 greatly fluctuates due to the input of vibration with a large amplitude, and the communication hole 42a When the liquid flows to and from the intermediate liquid chamber f3, a strong turbulent flow is generated in the pressure receiving chamber f1, and bubbles may be generated (cavitation) particularly in the vicinity of the communication hole 42a. Considering this point, it can be said that the structure as in the first embodiment is preferable.

  Although illustration is omitted, it is also possible to use an orifice board 4 like the modified example of the first embodiment (see FIG. 7) and to invert it upside down.

(Embodiment 3 and its modifications)
Next, FIG. 9 shows a longitudinal cross-sectional view of an engine mount A ′ according to Embodiment 3 of the present invention and its modification. Since the mount A ′ is generally structured such that the mount A of the first and second embodiments is inverted, members having the same function are denoted by the same reference numerals even if the shapes are different. Is attached.

  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 conical bowl shape whose diameter increases upward. Then, the orifice plate 4 and the diaphragm 5 are assembled to the main spring portion 20 from above to partition 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 pressure receiving chamber f1 and the intermediate liquid chamber f3. A communication hole 42a is formed in the membrane 42 between the equilibrium chamber f2 and the intermediate liquid chamber f3, so that the equilibrium chamber f2 and the intermediate liquid chamber f3 are substantially communicated with respect to a low frequency vibration input. ing. A movable plate 43 is accommodated inside the inner member 41 that divides the intermediate liquid chamber f3 and the pressure receiving chamber f1 so as to absorb fluid pressure fluctuations in the pressure receiving chamber f1 and the like.

  The engine mount A ′ according to the third embodiment can obtain the same effects as those of the first and second embodiments, and absorb and attenuate vibrations in a wide frequency range covering from shake vibration to idle vibration. Thus, the ride comfort of the vehicle can be improved.

  In the modification shown in FIG. 5B, the orifice plate 4 is turned upside down in the mount A ′ shown in FIG. 6A, and the intermediate liquid chamber f3 is provided on the pressure receiving chamber f1 side.

(Other embodiments)
The configuration of the vibration isolator according to the present invention is not limited to the above-described first to third embodiments, 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.

  Further, since the size of the communication hole 42a formed in the membrane 42 is an important factor affecting the characteristics of the engine mount as described above, the size, thickness, rubber hardness, etc. of the membrane 42 are taken into consideration. However, if the thickness of the membrane 42 is about 1.0 to 5.0 mm, the diameter of the communication hole 42a is 2.0 to 10.0 mm. It can be considered that the range should be set, and it can be said that the range of approximately 3.0 to 6.0 mm is particularly preferable from the example of FIG. The communication hole 42 a is not necessarily provided at the center of the membrane 42.

  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.

  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 ′. However, the present invention is not limited to this, and may be applied to a horizontal engine mount. It can be applied not only to the engine mount but also to a suspension bush, etc. Not only that, but it is also considered to be applicable to a vibration isolator other than an automobile.

  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 modification of the first embodiment. FIG. 3 is a diagram corresponding to FIG. 1 according to a second embodiment. It is a longitudinal cross-sectional view which shows the structure of the mount concerning Embodiment 3 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)
40 Outer member 41 Inner member (partition wall)
42 Membrane (elastic membrane member)
42a Communication hole 43 Movable plate

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 liquid chamber of either the main liquid chamber or the first sub liquid chamber is provided with a second sub liquid chamber communicated by a second orifice passage, and the second orifice passage is provided with the first orifice. It is at least one of shorter than the passage or larger in cross-sectional area,
The other liquid chamber of the main liquid chamber or the first sub liquid chamber and the second sub liquid chamber are partitioned by an elastic film member. The elastic film member includes the second liquid chamber and the second sub liquid chamber. A communication hole of a predetermined size is formed so as to communicate with the two sub liquid chambers,
Further, a partition wall is provided between the one liquid chamber and the second sub liquid chamber, and the partition wall moves under the pressure of the one liquid chamber and the second sub liquid chamber. A liquid-filled vibration damping device, wherein a movable plate is disposed so as to absorb fluctuations in fluid pressure in both chambers. A partition member for partitioning the main liquid chamber and the first sub liquid chamber; the first and second orifice passages are formed in the partition member; and the movable plate is also disposed.
Furthermore, the said partition member is formed with the recessed part opened facing the said 1st subliquid chamber, and this opening is covered with the said elastic film member, The 2nd subliquid chamber is formed. A liquid-filled vibration isolator as described in 1. 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 communication hole is formed at the approximate center of the elastic membrane member covering the opening of the concave portion of the partition member, while the bottom wall of the concave portion is a partition wall that partitions the main liquid chamber and the second sub liquid chamber, The liquid-filled vibration isolator according to claim 2, wherein a movable plate is disposed on the partition wall.   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