JPH08109941A - Damping force variable damper - Google Patents

Abstract

PURPOSE: To finely and widely adjust the damping force by a simple constitution, and to realize miniaturization, weight reduction and cost reduction of a damping force variable damper. CONSTITUTION: Two fluid chambers 24, 25 whose volume is changed by the external force are communicated with each other by a flow passage 26 whose sectional area. Is sufficiently smaller than that of these fluid chambers 24, 25, and the working fluid C is filled in the fluid chambers 24, 25 and the flow passage 26. An inserting member 27 which is inserted/drawn along the longitudinal direction is provided on the flow passage 26 to change the flow area of the working fluid C in the flow passage 26.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damper used to reduce shock or vibration by dissipating energy by utilizing viscous resistance and turbulent resistance of working fluid.

[0002]

2. Description of the Related Art Hitherto, as a damper of this type, a viscous damper using a silicone oil having a high viscosity and a small temperature change as a working fluid has been widely used. As this viscous damper, for example, there is a viscous damper of a direct-acting piston type as shown in FIG. In this viscous damper 1, two fluid chambers 4 and 5 partitioned in a cylinder 3 by a piston head 2 are in communication with each other by a flow passage 6 provided in the piston head 2 and having a sufficiently small cross-sectional area.

When the piston head 2 is moved in one direction by the external force transmitted through the rod 7, the volumes of the two fluid chambers 4 and 5 are changed accordingly, and this volume change is caused. Along with this, the working fluid C is moved from one fluid chamber 4 to the other fluid chamber 5 through the flow passage 6. As a result, a damping force proportional to the speed of the piston head 2 is generated by viscous resistance and turbulent flow resistance when the working fluid C flows through the flow passage 6.

[0004]

By the way, in such a damper 1, since the cross-sectional area of the flow passage 6 is fixed, the damping force thereof is proportional to only the velocity under the same temperature condition. Will change. In other words, under low-speed use conditions, the damper 1 can exert only a low damping force, and it is difficult to obtain a desired damping force according to the use conditions.

For example, taking a suspension of an automobile as an example, when the damper 1 is used, when the rod 7 of the damper 1 is displaced at a low speed, such as when the vehicle body is rolling in a curve, the damper 1 has a low damping force. It could not be exhibited, and rolling could not be effectively prevented. Further, in order to avoid this, if the cross-sectional area of the flow passage 6 is set to be small to increase the damping force as a whole, high damping is achieved when the damper 1 is displaced at a medium speed such as when traveling on a highway. There was an inconvenience that it generated force and deteriorated the riding comfort. Furthermore, if the damping coefficient of the damper 1 is set with an emphasis on comfortable riding comfort,
There is an inconvenience that a high damping force cannot be generated under a traveling condition in which the rod 7 of the damper 1 is displaced at a high speed such as when traveling on a rough road.

As a means for avoiding such inconvenience, development of a damping force variable damper using an electrorheological fluid whose viscosity is changed by applying a voltage as a working fluid C is under way. This damping force variable damper 10 is, for example, as shown in FIG.
Upper and lower fluid chambers 13 and 14 composed of 1 and 12,
A flow passage 15 that connects these fluid chambers 13 and 14 is provided. The rod 16 fixed to the bottom surface of the lower fluid chamber 13 penetrates the flow passage 15 and the fluid chamber 14 on the other side.
Is projected from the upper surface to the outside to transmit the outer force acting in the vertical direction.

The fluid chambers 13 and 14 and the flow passage 15 are filled with an electrorheological fluid (working fluid) C. As the electrorheological fluid C, for example, one in which carbonaceous particles are dispersed in silicon oil and which can change the viscosity by causing interfacial polarization by the movement of electrons when a voltage is applied is used. Has been done.

Further, the rod 16 and the wall surface 17 of the flow passage 15 facing the rod 16 are provided so as to form electrodes, respectively, and the electric power arranged in the cylindrical flow passage 15 formed by these electrodes is formed. The viscosity of the viscous fluid C can be changed. According to this, there is an advantage that the damping coefficient of the damping-force variable damper 10 can be changed by applying a voltage according to the use condition, and an optimal damping force can be exhibited. In this case, when the damping force variable damper 10 using the electrorheological fluid C is used to further finely adjust the damping force, it is possible to change the voltage applied to the electrodes.

However, since the voltage value to be applied to the electrorheological fluid C is as large as several kV, when a high voltage and variable voltage power supply is used, the structure becomes complicated and the device becomes There is an inconvenience that it becomes a large-scale one. Therefore, it is difficult to apply the above in-vehicle device in terms of size, weight and cost.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to finely and widely adjust the damping force with a simple structure and to achieve compactness, weight reduction and cost reduction. The purpose is to provide a variable damping force damper.

[0011]

In order to achieve the above-mentioned object, the present invention connects two fluid chambers whose volumes are changed by an external force by a flow passage having a cross-sectional area sufficiently smaller than those of the fluid chambers. Damping in which working fluid is filled in the fluid chamber and the flow passage, and an insertion member is provided in the flow passage to change the flow area of the working fluid in the flow passage by inserting and removing the working fluid. A force variable damper is proposed.

Further, in the above damping force variable damper, it is effective that the insertion member is provided with a plurality of insertion portions having different cross-sectional areas along the longitudinal direction of the flow passage. Further, it is more effective if the working fluid is an electrorheological fluid and the wall surface and the insertion member forming the flow passage are electrodes for applying a voltage to the electrorheological fluid.

[0013]

According to the damping force variable damper of the present invention, when the insertion member is inserted into the flow passage, the sectional area of the flow passage is reduced. Further, when the insertion member is pulled out from the flow passage, the cross-sectional area of the flow passage is enlarged. This gives, for example,
If the insertion member is displaced by an external force that changes the volume of the fluid chamber, the damping force can be changed according to the magnitude of the external force. Further, even if the insertion member is displaced by another actuator, it is possible to operate in the same manner as above.

Further, in the above damping force variable damper, if the insertion member is formed in a rod shape having a plurality of insertion portions having different cross-sectional areas, the cross-sectional area of each insertion portion inserted into the flow passage is adjusted. It is possible to change the distribution area. Therefore, the damping force can be changed more finely.

Moreover, the working fluid is an electrorheological fluid,
If a voltage is applied to the electrorheological fluid arranged in the flow passage by using the insertion member and the wall surface of the flow passage facing the insertion member as an electrode, in addition to the change in the damping force due to ON / OFF of the power supply, Since the viscosity is changed by the change of the cross-sectional area of the flow passage and the change of the length, width and the distance between the electrodes, it is possible to finely and widely adjust the damping force.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a damping force variable damper according to the present invention will be described below with reference to FIGS. The damping force variable damper 20 according to the present embodiment also uses an electrorheological fluid as the working fluid C, and as shown in FIG. 1, a casing 21 fixed to a structure such as a vehicle body (not shown), Two upper and lower fluid chambers 24 and 25 formed by rubber sleeves 22 and 23 fixed to the casing 21 and opposed to each other, and a flow passage 26 provided in the vertical direction so as to connect these fluid chambers 24 and 25 to each other. , A rod 27 fixed to the bottom surface 24a of the lower fluid chamber 24 and penetrating the flow passage 26 and the upper surface 25a of the upper fluid chamber 25 and having a tip arranged upward. Have in common. Further, the damping force variable damper 20 of this embodiment is
In the conventional configuration, the rod 27 and the wall surface forming the flow passage 26 are formed of electrodes that form the cylindrical flow passage 26 and apply a voltage to the electrorheological fluid C disposed in the flow passage 26. It is common with the example.

However, the damping force variable damper 20 according to the present embodiment differs from the conventional damping force variable damper 10 in the shape of the rod 27. That is, as shown in FIG. 2, the rod 27 of the damping force variable damper 20 according to the present embodiment has two insertion portions 29a having different cross-sectional areas.
-Has 29b arranged in the axial direction. These insertion portions 29a and 29b are arranged, for example, along the axial direction of the rod 27 so as to sequentially increase the cross-sectional area from the bottom. As a result, the rod 27 is formed in a shape having a step.

Damping force variable damper 2 constructed in this way
The operation of 0 will be described below. First, when no voltage is applied between the electrodes, the viscosity of the electrorheological fluid C is maintained at a small value and the damping force variable damper 20 having a small damping force F is maintained.
Function as

That is, when the rod 27 is displaced downward by an external force, the bottom surface 24a of the lower fluid chamber 24 is displaced downward by the rod 27, and the volume of the lower fluid chamber 24 is increased. The electrorheological fluid C flows downward in the flow passage 26, and the volume of the upper fluid chamber 25 is reduced. Then, the viscous resistance and the turbulent resistance generated when the electrorheological fluid C passes through the flow passage 26 having a small flow cross-sectional area generates a damping force F proportional to the moving speed of the rod 27, thereby damping the external force. Will be done.

In this case, the rod 2 having a certain size or more
When 7 is displaced and an external force is applied,
The rod 27 is further displaced, and the upper insertion portion 29b having a large cross-sectional area is arranged in the flow passage 26 in an inserted state, as shown by a chain line in FIG. As a result, the gap size between the rod 27 and the wall surface 28 of the flow passage 26 becomes H ₁
Since the flow cross-sectional area of the flow passage 26 is reduced by narrowing the flow path 26 from H ₂ to H ₂ , the generated viscous resistance and turbulent flow resistance are increased, and the damping force F is increased.

Next, the case where a voltage is applied between the electrodes will be described. In this case, the viscosity of the electrorheological fluid C is increased to a large value and the damping force variable damper 20 having a large damping force F is caused to function. The action of the damping force variable damper 20 in this case is basically the same as that when no voltage is applied between the electrodes except that the magnitude of the damping force F is different, but the insertion portion having a large cross-sectional area. 29b acts differently when inserted into the flow passage 26.

That is, the damping force F of the damping force variable damper 20 is expressed by the following equation (1). F = 12 × A ² × L × V × η / (B × H ³ ) + 3 × A × L × τ _y / H (1) where the symbol F is damping force and A is fluid chamber disconnection Area, V is the velocity of the rod 27, L is the electrode length, B is the electrode width, H is the electrode gap, η is the viscosity of the electrorheological fluid C, and τ _y is the electrorheological fluid C.
Is the yield stress.

In the above equation (1), the first term represents the viscous damping force, and the second term represents the damping force obtained when a voltage is applied. According to this equation (1), since the damping force F also changes depending on the dimensions L, B, and H of the electrodes, the electrode gap H decreases from H ₁ to H ₂ in the second term. The damping force F of the generated second term also increases,
In addition to the increase of the damping force F in the first term due to the reduction of the flow area, the damping force F can be increased or decreased more effectively.

As described above, according to the damping force variable damper 20 of this embodiment, since the electrorheological fluid C is used, the damping force F according to the use condition can be obtained by turning the voltage ON / OFF. In addition, the damping force F can be adjusted by changing the electrode gap by using the rod 27 whose cross-sectional area changes as an electrode. Therefore,
Since it is possible to perform the stepwise adjustment of the damping force F without using a high-voltage and variable-voltage power source for changing the voltage, it is possible to prevent the apparatus from increasing in size and weight and increasing the weight of the apparatus. The application can be facilitated and the cost can be reduced.

In this embodiment, the damping force variable damper 20 in which the shape of the rod 27 as an electrode is changed while adopting the same structure as the conventional one is adopted.
The structure is not limited to this. That is,
Although the rod 27 that transmits the external force is used as one of the electrodes, the present invention is not limited to this, and the electrode is separated from the rod 27,
Only the electrodes may be inserted into and removed from the flow passage 26, and external force may be applied to the lower fluid chamber 24 via another member or directly.

Further, the rod 27 is moved by the external force to the flow passage 2
Instead of the structure in which the rod 27 is inserted and removed, a structure in which the rod 27 is displaced independently of the action of the external force or incidentally by another arbitrary actuator may be adopted. Further, the insertion portions 29a and 29b provided on the rod 27
The outer diameter dimension can be appropriately set according to the damping force F to be adjusted, and the number and length of the insertion portions 29a and 29b can be arbitrarily set. Also, the cross-sectional shape is gradually increased along the longitudinal direction of the rod 27,
The cross-sectional shape may be smoothly changed with a taper shape or another arbitrary curved surface.

In the above embodiment, the rod 27 has a shape in which the cross-sectional area is changed in two steps. However, the shape is not limited to this, and it may be changed in three or more steps. Also,
Although the damping force variable damper 20 using the electrorheological fluid C is described in the above embodiment, instead of this, a cross-sectional area of the rod 27 is used for a damping force variable damper using a normal working fluid such as silicon oil. The damping force F can be adjusted by changing the distribution area even with the configuration in which is changed.

[0028]

As described in detail above, the damping force variable damper according to the present invention can change its volume by an external force.
The two fluid chambers are connected by a flow passage having a cross-sectional area sufficiently smaller than those of the fluid chambers, the working fluid is filled in the fluid chambers and the flow passages, and the flow passages are inserted and removed along the longitudinal direction. Since the insertion member that changes the flow area of the working fluid in the flow passage is provided, the flow area of the flow passage is changed by inserting and removing the insertion member into the flow passage, and the viscous resistance of the working fluid is changed to reduce the damping force. The effect is that it can be adjusted.

In the damping force variable damper, if the insertion member is formed in a rod shape having a plurality of insertion portions having different cross-sectional areas along the longitudinal direction of the flow passage, the operation in the flow passage is performed. There is an effect that the flow area of the fluid can be changed for each insertion portion arranged in the flow passage, and the damping force can be adjusted in multiple steps.

Further, the working fluid is an electrorheological fluid, and the wall surface and the insertion member forming the flow passage are
In addition to the above effects, the viscosity of the working fluid is changed stepwise by turning the voltage ON / OFF to provide an appropriate damping force according to the use condition, in addition to the above-mentioned effects. Can be caused,
There is an effect that the damping force can be finely and widely adjusted with a simple configuration without using a high-voltage and variable-voltage power supply facility and its control device.

Moreover, since the above effects can be more efficiently exhibited in accordance with changes in the electrode gap and changes in the electrode dimensions, it is possible to achieve compactness, weight reduction and cost reduction, and various devices. Can be applied to.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a damping force variable damper according to the present invention.

FIG. 2 is an enlarged cross-sectional view showing the shape of a rod of the damping force variable damper of FIG.

FIG. 3 is a vertical cross-sectional view showing a conventional example of a damping force variable damper.

FIG. 4 is a vertical sectional view showing another conventional example of the damping force variable damper.

[Explanation of symbols]

C ... Electrorheological fluid (working fluid), 20 ... Damping force variable damper, 24/25 ... Fluid chamber, 26 ... Flow passage, 27
.... Rods (insertion members), 29a, 29b, ... Insertion parts

Claims (3)

[Claims] 1. A fluid passage (26) communicating with two fluid chambers (24, 25) whose volume can be changed by an outer chamber and having a cross-sectional area sufficiently smaller than these fluid chambers. Is filled with the working fluid (C), and the flow passage is provided with an insertion member (27) which is inserted / removed along the longitudinal direction thereof to change the flow area of the working fluid. Variable damping force damper. 2. The damping according to claim 1, wherein the insertion member is formed in a rod shape having a plurality of insertion portions (29a, 29b) having different cross-sectional areas along the longitudinal direction of the flow passage. Variable force damper. 3. The working fluid is an electrorheological fluid, and the wall surface and the insertion member forming the flow passage are electrodes for applying a voltage to the electrorheological fluid. The damping force variable damper described in 2.