JPH07224885A - Vibration absorbing device - Google Patents

Abstract

PURPOSE:To perform effective absorption of high frequency vibration by locating magnetic fluid between the electromagnetic coil and the moving plate of a vibration absorbing device to control the position of the moving plate by the passage of a flow substance in a resilient body through a buffering hole and an electromagnetic coil. CONSTITUTION:When coil 4a and 4b are charged with a current 0, a magnetic flux is returned to a permanent magnet 6 through the permanent magnet 6, magnetic fluid 13, a moving plate 7, the magnetic fluid 13, and a yoke 5. Since, when a current is +1, the attraction force of the permanent magnet 6 is high and a gap between the moving plate 7 and the permanent magnet 6 is reduced, the magnetic fluid 13 flows between the coils 4a and 4b and the moving plate 7 and a leak magnetic flux not passing the magnetic flux described above and the moving plate 7 is present. Since the more the moving plate 7 approaches the permanent magnet 6, the more the leakage magnetic flux is increased, the increase of an attraction force when the moving plate 7 approaches the permanent magnet 6 is suppressed. Thus, when positive and negative currents the absolute values of which are equal to each other are caused to flow, displacement amounts of the moving plates 7 on the positive side and the negative side are approximately equal to each other, the displacement amounts of the moving plates 7 are properly controllable and vibration of a high frequency is effectively absorbed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration absorbing device such as an engine mount for supporting an engine on a vehicle body in a vibration-proof manner.

[0002]

2. Description of the Related Art A conventional vibration absorbing device is disclosed in Japanese Patent Laid-Open No. Hei 3
No. 24338 has been disclosed. In this vibration absorbing device, the working fluid enclosed in the working chamber passes through the buffer holes due to the vibration to keep the internal hydraulic pressure constant, and the movable plate that constitutes the working chamber can accommodate a change in hydraulic pressure that cannot be absorbed by this means. It is absorbed by being displaced by an electromagnet.

FIG. 7 is a sectional view showing a conventional engine mount having the above-mentioned structure, and FIG. 8 is a view showing a control device for the engine mount shown in FIG. As shown in the figure, a mounting member 15 is mounted on a support body 1 to which an engine (not shown) is to be mounted, and the pressure control chamber 11 formed by the support body 1 and the mounting member 15 has flexibility. A wall 12 is provided, a rubber spring 2 made of elastic rubber having a hollow conical shape is attached to a mounting member 15, a metal outer shell 3 to which a vehicle body (not shown) is to be attached to the rubber spring 2, and an outer shell 3 Is provided with a yoke 5, coils 5a, 4b and a permanent magnet 6 are provided on the yoke 5, and the yoke 5, coils 4a, 4b and the permanent magnet 6 constitute an electromagnet 14. Further, a movable plate 7 is provided in the outer shell 3 via a support spring 8 made of elastic rubber, the movable plate 7 faces the permanent magnet 6, and the movable plate 7 and the permanent magnet 6 are provided.
A space is provided between and. Also, the mounting member 1
5, the rubber spring 2, the movable plate 7 and the like form a working chamber 9, a mounting member 15 is provided with a buffer hole 10 for communicating the working chamber 9 and the pressure adjusting chamber 11, and a working fluid is enclosed in the working chamber 9. ing. Further, a crank angle sensor 21 for detecting the crank angle of the engine and an acceleration sensor 22 for detecting the vibration of the vehicle body are connected to the CPU 23.
Drive circuits 24a and 24b for driving 4b are connected.

In this engine mount, when vibration from the engine is applied to the support plate 1, the support plate 1 moves relative to the outer shell 3 via the rubber spring 2. At this time, when the vibration has a relatively low frequency, a part of the hydraulic fluid in the working chamber 9 compressed by the deformation of the rubber spring 2 is accommodated in the pressure regulating chamber 11 via the buffer hole 10 without pressure. The hydraulic pressure of the working fluid in the working chamber 9 does not change. Then, when the vibration has a high frequency, the same state as when the buffer hole 10 is closed and the hydraulic pressure of the working fluid in the working chamber 9 fluctuates. Therefore, the current determined by the CPU 23 based on the signals from the crank angle sensor 21 and the acceleration sensor 22 is applied to the drive circuits 24a and 24b.
By flowing through the coils 4a and 4b through the magnets, the magnetic force of the permanent magnet 6 is increased or decreased according to the crank angle of the engine and the vibration of the vehicle body, the movable plate 7 is displaced, and the hydraulic pressure of the hydraulic fluid in the working chamber 9 is increased. It prevents it from fluctuating.

[0005]

By the way, in FIG. 9, currents + I (A), 0 (A), -I (A) are applied to the coils 4a, 4b.
The relationship between the gap distance between the permanent magnet 6 and the movable plate 7 and the attraction force of the electromagnet 14 to the movable plate 7 when the current flows, that is, the attraction force characteristic, the gap distance between the permanent magnet 6 and the movable plate 7, and the support spring 8 6 is a graph showing a relationship with a force acting on the movable plate 7, that is, a thrust characteristic. Here, the current that strengthens the magnetic force of the permanent magnet 6 is a positive current. As is clear from this graph, the attraction force of the movable plate 7 by the electromagnet 14 is 2
The attraction force characteristic curves are not parallel because they are inversely proportional to the power. The gap distance when the current + I (A) is passed, that is, the maximum displacement on the positive side of the movable plate 7 (when the movable plate 7 is displaced to the permanent magnet 6 side) is the intersection of the attractive force characteristic curve and the thrust characteristic line. It becomes Xa corresponding to a, and when the current -I (A) is passed, the gap distance, that is, the maximum displacement on the negative side of the movable plate 7 (when the movable plate 7 is displaced to the side opposite to the permanent magnet 6) is the attraction force characteristic. It becomes Xb corresponding to the intersection point b between the curve and the thrust force characteristic line, and the gap distance when the current 0 (A) is passed, that is, the initial position of the movable plate 7 corresponds to the intersection point 0 between the attraction force characteristic curve and the thrust force characteristic line. It becomes X0. Therefore, the current is -I
The moving amount of the movable plate 7 when changing from (A) to + I (A) is (Xb-Xa), but the maximum positive displacement amount (X0-Xa) of the movable plate 7 is Maximum negative displacement (X
b-X0). Thus, as shown in FIG. 10, when positive and negative currents having the same absolute value are passed through the coils 4a and 4b, the displacement amount of the movable plate 7 on the positive side is larger than the displacement amount of the movable plate 7 on the negative side.

Therefore, in the engine mount shown in FIGS. 7 and 8, even if the magnetic force of the electromagnet 14 is increased or decreased according to the crank angle of the engine and the vibration of the vehicle body, the magnetic field of the engine crank angle and the vehicle body vibration are changed. Since it is impossible to properly control the displacement amount of the movable plate 7, it is impossible to effectively prevent the hydraulic pressure of the working fluid in the working chamber 9 from varying, and therefore it is possible to effectively absorb the high frequency vibration. I can't.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a vibration absorber capable of effectively absorbing high frequency vibration.

[0008]

To achieve this object, in the present invention, a working chamber and a pressure adjusting chamber are formed inside a hollow elastic body, and the working chamber and the pressure adjusting chamber are communicated with each other. A buffer hole is provided, a part of the working chamber is formed by a movable plate, and an electromagnetic coil and a permanent magnet are provided so as to face the movable plate. A magnetic fluid is provided between the electromagnetic coil and the movable plate in a vibration absorber that absorbs the vibration of the vibrating body by controlling the position of the movable plate by the electromagnetic force of the coil.

[0009]

In this vibration absorbing device, when the movable plate approaches the permanent magnet side, the magnetic fluid collected by the magnetic force of the permanent magnet enters between the electromagnetic coil and the movable plate to short-circuit the magnetic path of the permanent magnet. Since the path is formed, the amount of leakage flux that does not pass through the movable plate increases, and the magnetic force of the permanent magnet on the movable plate decreases. On the other hand, when the movable plate is separated from the permanent magnet, the magnetic fluid does not enter between the electromagnetic coil and the movable plate, so that a path that short-circuits the magnetic path of the permanent magnet is not formed and leakage flux that does not pass through the movable plate is generated. It is possible to suppress the decrease in the magnetic force of the permanent magnet with respect to the movable plate. Accordingly, the suction force applied to the movable plate can be adjusted depending on the position of the movable plate, so that the displacement amount according to the position of the movable plate can be made substantially equal.

[0010]

1 is a sectional view showing an engine mount according to the present invention. The engine mount control device according to the present embodiment is the same as that shown in FIG. 7, and therefore its section name is omitted here. As shown in the figure, a magnetic fluid 13 is provided between the electromagnet 14 and the movable plate 7, and the magnetic fluid 13 includes the yoke 5 and the coil 4 of the electromagnet 14.
a, 4b, in contact with the permanent magnet 6, and the magnetic fluid 1
3 is also in contact with the movable plate 7.

In this engine mount, when a current of 0 (A) is applied to the coils 4a and 4b, the magnetic flux is a permanent magnet 6, a magnetic fluid 13, a movable plate 7, a magnetic fluid 13 and a yoke as shown in FIG. Return to the permanent magnet 6 through 5. When a current + I (A) is applied to the coils 4a and 4b, the attractive force of the permanent magnet 6 increases and the gap between the movable plate 7 and the permanent magnet 6 decreases, as shown in FIG. Since the fluid 13 enters between the coils 4a and 4b and the movable plate 7 to form a path that short-circuits the magnetic path of the permanent magnet 6, the permanent magnet 6, the magnetic fluid 13 as described above,
Permanent magnet 6 through movable plate 7, magnetic fluid 13 and yoke 5.
There is a magnetic flux returning to the permanent magnet 6, a magnetic flux passing through the permanent magnet 6, the magnetic fluid 13, and the yoke 5, that is, a leakage magnetic flux not passing through the movable plate 7. The leakage magnetic flux becomes larger as the movable plate 7 approaches the permanent magnet 6. For this reason,
It is possible to suppress an increase in attraction force when the movable plate 7 approaches the permanent magnet 6. On the other hand, the coils 4a, 4
When a current -I (A) is applied to b, the absorption force of the permanent magnet 6 becomes small and the gap between the movable plate 7 and the permanent magnet 6 becomes large as shown in FIG. ,
The leakage flux that returns to the permanent magnet 6 through the magnetic fluid 13, the movable plate 7, the magnetic fluid 13, and the yoke 5 and does not pass through the movable plate 7 is extremely reduced. Therefore, it is possible to suppress a decrease in the attractive force when the movable plate 7 moves away from the permanent magnet 6. From the above, as shown in FIG. 5, since the attraction force characteristic curves are substantially parallel to each other, the positive side maximum displacement amount (X0-Xa) of the movable plate 7 and the negative side maximum displacement amount of the movable plate 7 ( Xb-X
0), and as shown in FIG. 6, when positive and negative currents having the same absolute value are applied to the coils 4a and 4b, the displacement amount of the movable plate 7 on the positive side and the displacement amount of the movable plate 7 on the negative side are equal to each other. Is almost equal to. Therefore, in the engine mount shown in FIG. 1, since the displacement amount of the movable plate 7 can be appropriately controlled according to the crank angle of the engine and the vibration of the vehicle body, the hydraulic pressure of the working fluid in the working chamber 9 is reduced. Since the fluctuation can be effectively prevented, the high frequency vibration can be effectively absorbed. Further, in the engine mount shown in FIG. 1, heat generated when an electric current is applied to the coils 4a and 4b is radiated to the movable plate 7 side through the magnetic fluid 13, so that the permanent magnet 6 and the coils 4a and 4b. Since it is possible to prevent the temperature from rising, it is possible to prevent the performance of the electromagnet 14 from decreasing and the power consumption from increasing.

Although the engine mount has been described in the above embodiment, it is obvious that the present invention can be applied to other vibration absorbing devices. Further, in the above embodiment, the rubber spring 2 is used as the hollow elastic body, but another hollow elastic body may be used.

[0013]

As described above, in the vibration absorbing device according to the present invention, it is possible to prevent the attraction force from increasing when the movable plate approaches the electromagnetic coil side, and to reduce the attraction force when the movable plate moves away. Since it can be suppressed, the amount of displacement corresponding to the position of the movable plate can be made substantially equal, so that fluctuations in the hydraulic pressure of the working fluid in the working chamber can be effectively prevented, and high-frequency vibrations can be effectively absorbed. it can.

[Brief description of drawings]

FIG. 1 is a sectional view showing an engine mount according to the present invention.

FIG. 2 is an operation explanatory view of the engine mount shown in FIG.

FIG. 3 is an operation explanatory view of the engine mount shown in FIG.

FIG. 4 is an operation explanatory view of the engine mount shown in FIG.

5 is a graph showing attraction force characteristics and thrust force characteristics of the engine mount shown in FIG.

6 is a graph showing characteristics of an electromagnet section of the engine mount shown in FIG.

FIG. 7 is a cross-sectional view showing a conventional engine mount.

8 is a diagram showing a control device for the engine mount shown in FIG. 7. FIG.

9 is a graph showing attraction force characteristics and thrust force characteristics of the engine mount shown in FIG.

10 is a graph showing characteristics of an electromagnet section of the engine mount shown in FIG.

[Explanation of symbols]

 2 ... Rubber spring 7 ... Movable plate 9 ... Working chamber 10 ... Buffer hole 11 ... Pressure adjusting chamber 13 ... Magnetic fluid 14 ... Electromagnet

Claims (1)

[Claims] 1. A working chamber and a pressure adjusting chamber are formed inside a hollow elastic body, a buffer hole is provided to connect the working chamber and the pressure adjusting chamber, and a part of the working chamber is a movable plate. An electromagnetic coil and a permanent magnet are provided facing the movable plate.
In a vibration absorber that absorbs vibration of the vibrating body by passing the fluid in the elastic body through the buffer hole and controlling the position of the movable plate by the electromagnetic force of the electromagnetic coil, between the electromagnetic coil and the movable plate. A vibration absorbing device provided with a magnetic fluid.