JPH11101293A - Damper using electrorheological fluid - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent damping force from becoming excessive at the start of operation of a damper and improve damping force characteristics and reliability. A rotary shaft is rotatably provided in a casing of a rotary damper, and a mounting arm is provided on the rotary shaft. The electrorheological fluid contained in the casing 1 generates a damping force when the rotating shaft 7 rotates relatively to the casing 1. Further, the rotation angle sensor 2
4. The acceleration sensor 25 detects a relative rotation displacement between the rotation shaft 7 and the casing 1. And controller 2
6 controls the damping force of the rotary damper by changing the electric field applied to the electrorheological fluid, and when the rotating shaft 7 starts rotating relative to the casing 1, the damping force of the rotary damper is controlled. Is temporarily reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damper using an electrorheological fluid which is suitably used for, for example, damping the vibration of a vehicle.

[0002]

2. Description of the Related Art In general, a damper using an electrorheological fluid is provided with a casing containing the electrorheological fluid therein, and slidably provided in the casing, and first and second liquid chambers are provided in the casing. And a flow path means for flowing an electrorheological fluid between the first and second liquid chambers when the movable partition is displaced relative to the casing, and the flow path It comprises a pair of electric field cylinders provided opposite to each other in the middle of the means and applying an electric field to the electrorheological fluid, and is constituted as a rotary damper used for a vehicle such as an automobile (Japanese Patent Laid-Open No. 8-177939). ).

[0003] In a rotary damper of this kind in the prior art, a rotating shaft is rotatably provided in a cylindrical casing, and a movable vane as a movable partition is attached to the rotating shaft. The movable vane defines first and second liquid chambers with a fixed vane or the like mounted in the casing.

On the inner peripheral side of the casing and on the outer peripheral side of the rotating shaft, inner and outer electrode tubes are disposed so as to be coaxial with each other. An annular flow path that forms a part is formed. Further, each electrode tube is connected to a controller for controlling a damping force, and this controller variably controls an electric field applied between each electrode tube.

Here, the electrorheological fluid is obtained by dispersing colloidal fine particles or the like in a liquid, and is configured so that the substantial viscosity changes according to the magnitude of the electric field.
The electrorheological fluid is a fluid (a so-called Bingham fluid) that maintains a constant shear stress even when the shear rate is zero when an electric field is applied.

[0006] The rotary damper thus configured is
For example, a rotating shaft is fixed to a vehicle body side of an automobile or the like, and a casing is fixed to a swing arm or the like that swingably supports a wheel side. When the swing arm swings up and down with respect to the vehicle body side due to vibrations during traveling, the rotating shaft is relatively displaced relative to the casing, so that the electrorheological fluid is displaced in each electrode tube. The liquid flows between the first and second liquid chambers through a flow path between them. Thereby, between the casing and the rotating shaft,
A damping force is generated due to the viscous resistance of the electrorheological fluid, and the damping force buffers vibrations of the vehicle body.

[0007]

By the way, in the above-mentioned prior art, since the vibration or the like of the vehicle is attenuated by always applying an electric field to the electrorheological fluid, for example, when the rotary damper starts the damper operation. In addition, there is a problem that the damping force becomes excessively large and the riding comfort of the vehicle cannot always be improved.

That is, the electrorheological fluid becomes a Bingham fluid when an electric field is applied, and an electric field is always applied between the electrode cylinders to maintain a constant shear stress even when the shear rate is zero. In this state, a relatively large flow resistance is generated in the electrorheological fluid at the start of the damper operation, and the damping force becomes excessive, so that there is a problem that vibrations from the road surface are easily transmitted to the vehicle body.

The present invention has been made in view of the above-mentioned problems of the prior art, and the present invention can prevent the damping force of the damper from becoming excessive when the movable partition starts relative displacement with respect to the casing. It is an object of the present invention to provide a damper using an electrorheological fluid which can satisfactorily buffer vibrations and the like and can improve the reliability as a damper.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a casing for containing an electrorheological fluid therein, a slidably provided casing, and first and second casings inside the casing. A movable partition defining a second liquid chamber, and a flow path means for flowing an electrorheological fluid between the first and second liquid chambers when the movable partition relatively slides and displaces with respect to the casing. An electric field providing means for providing an electric field to the electrorheological fluid, a displacement detecting means for detecting a relative displacement of the movable partition with respect to the casing, and a detection signal from the displacement detecting means. Displacement determining means for determining whether or not the movable partition has started relative displacement with respect to the casing in accordance with the following; and temporarily reducing the electric field applied to the electric field applying means when the displacement determining means determines that relative displacement has started. It adopts a configuration comprising a field control unit.

With this configuration, when the movable partition wall is slid relative to the casing, the electrorheological fluid in the casing is transferred between the first and second liquid chambers through the flow path means. At this time, by applying an electric field to the electrorheological fluid from the electric field control means via the electric field applying means, the viscosity of the electrorheological fluid can be changed and the damping force of the damper can be variably controlled. The displacement determining means determines whether or not the relative displacement between the casing and the movable partition has started based on a detection signal from the displacement detecting means. At the start of the relative displacement, the electric field applied to the electric field applying means by the electric field control means is determined. The damping force can be temporarily reduced, and the damping force can be kept low at the start of the operation of the damper.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to FIGS. 1 to 8 by taking a rotary damper used for a vehicle such as an automobile as an example.

Reference numeral 1 denotes a casing serving as a main body of the rotary damper. As shown in FIGS. 1 to 4, the casing 1 is attached to a substantially cylindrical casing main body 2 and both ends of the casing main body 2 in the axial direction. And disk-shaped lid plates 3 and 4 that seal the inside of the casing body 2.
Are provided with bearings 3A and 4A.

Here, the rotary damper is a casing 1
Is integrally attached to, for example, a swing arm (not shown) provided on a wheel (axle) side of the vehicle, and a rotating shaft 7 described later.
Is mounted on the vehicle body side via the mounting arm 8. A plurality of fixed vanes 5, 5,... Protruding radially inward are provided in the casing body 2,
Each fixed vane 5 has its protruding end side slidingly in contact with the outer peripheral side of a rotating cylinder 9 described later, and extends between the cover plates 3 and 4 in the axial direction.

Reference numeral 6 denotes an electrorheological fluid accommodated in the casing 1. The electrorheological fluid 6 is obtained by dispersing colloidal fine particles in a liquid.
In this configuration, the substantial viscosity changes according to the electric field given by the device. The electrorheological fluid 6 is a Bingham fluid when an electric field is applied.

Numeral 7 designates a bearing 3 located in the casing 1.
A, 4A, which is rotatably supported on the rotating shaft 7
, Both ends in the axial direction protrude from the casing 1 to the outside,
For example, it is integrally mounted on the vehicle body side of the vehicle via a substantially U-shaped mounting arm 8. Then, when vibration or the like from the road surface acts, the rotating shaft 7 is relatively displaced relative to the casing 1 in directions indicated by arrows R1 and R2 in FIG.

Reference numeral 9 denotes a rotating cylinder which constitutes a movable partition wall together with a movable vane 11 which will be described later. The rotating cylinder 9 is coaxially arranged in the casing 1 as shown in FIGS. It is fixed to the outer peripheral side of the rotating shaft 7 via annular partition plates 10, 10. Also, on the outer peripheral side of the rotating cylinder 9, a plurality of movable vanes 11, 11,.
Each of the movable vanes 11 has a protruding end side in sliding contact with the inner peripheral side of the casing body 2 and extends axially between the cover plates 3 and 4.

Here, each movable vane 11 defines first and second liquid chambers A1 and A2 each having a fan-shaped cross section between each movable vane 11 and each fixed vane 5, respectively. , A2 is
The casing body 2 and the rotating cylinder 9 are alternately arranged along the circumferential direction. And the rotating shaft 7 is the casing 1
4, the volumes of the liquid chambers A1 and A2 decrease and increase, respectively, when the rotary shaft 7 relatively rotates in the direction of arrow R2. ,
The volume of A2 increases and decreases respectively.

The rotating cylinder 9 has a plurality of flow holes 9A, 9A.
B is formed, and the liquid chamber A1 communicates with a later-described circulation chamber B1 through a circulation hole 9A, and the liquid chamber A2 communicates with the circulation chamber B2 through a circulation hole 9B.

Reference numerals 12 and 13 denote stepped cylindrical valve seat members provided between the partition plates 10 so as to be spaced apart in the axial direction. The valve seat members 12 and 13 are, as shown in FIG. The annular flow chambers B1 and B2 are fixed between the rotary cylinder 7 and the rotary cylinder 9 and define annular flow chambers B1 and B2 between the partition plates 10 respectively. In addition, the valve seat member 12
Are provided with a plurality of liquid holes 12A for communicating the flow chamber B1 and a flow chamber C to be described later, and a damping valve 14 for opening and closing the respective liquid holes 12A. Liquid hole 1
3A, a damping valve 15 is provided.

The damping valves 14 and 15 give a constant throttle resistance to the electrorheological fluid 6 flowing into the flow chamber C from the flow chambers B1 and B2, and regulate the reverse flow of the flow. The valve seat member 12 has a communication passage 12B opened to a flow chamber D described later, and the valve seat member 13 also has a communication passage 13B.

Reference numerals 16 and 17 denote electrode cylinders as electric field applying means for applying an electric field to the electrorheological fluid 6.
As shown in FIG. 5, both ends are attached to the outer peripheral sides of the valve seat members 12 and 13 via the support member 18 and the insulating member 19 and face each other with the annular throttle passage 20 therebetween. Insulated from each other.

Here, the electrode tube 16 on the outer peripheral side is
And an annular circulation chamber C is defined between them and is connected to, for example, the ground side. Further, the electrode cylinder 17 on the inner peripheral side is
And a controller 26 to be described later via a lead wire 21 and the like disposed in the rotating shaft 7.
Is connected to the output side. Furthermore, the distribution rooms C and D
Communication holes 16A, 17A formed in electrode tubes 16, 17
And the throttle passage 20.

The flow chambers C and D are provided with flow holes 9A and 9
B, the liquid holes 12A and 13A, the communication paths 12B and 13B, the communication holes 16A and 17A, the throttle path 20, and the flow path means provided between the first and second liquid chambers A1 and A2 together with the flow chambers B1 and B2. Make up.

Reference numerals 22 and 23 denote check valves provided on the valve seat members 12 and 13, respectively.
3, permits the electrorheological fluid 6 to flow from the flow chamber D into the flow chambers B1 and B2 via the communication paths 12B and 13B, and regulates a reverse flow to this flow.

On the other hand, reference numeral 24 denotes a rotation angle sensor as displacement detection means provided on the rotation shaft 7.
As shown in FIG. 1 and FIG.
5 together with the input side of the controller 26.
The rotation angle sensor 24 determines that the rotation shaft 7 is movable vane 1.
1 and the like, for example, when the casing 1 is displaced relative to the casing 1 by a pivot angle θ shown in FIG.
Output a detection signal.

Reference numeral 25 denotes an acceleration sensor provided on the mounting arm 8. The acceleration sensor 25 detects acceleration acting on the vehicle body due to vibration from the road surface or the like, and outputs a detection signal to the controller 26. .

Reference numeral 26 denotes a controller for performing damping force control. As shown in FIG. 2, the controller 26 includes an arithmetic processing unit (not shown) including a microcomputer and the like.
The storage unit 26A includes a ROM, a RAM, and the like.
The storage unit 26A stores a damping force control processing program shown in FIGS. 6 and 7 and a correction coefficient f described later.
(N) characteristic line data (see FIG. 8) and the like are stored in advance. Further, on the input side of the controller 26, for example, various sensors such as a vehicle speed sensor, a vehicle height sensor, and a steering angle sensor (none of which are shown) provided in the vehicle are provided with the rotation angle sensor 2.
4. Connected with the acceleration sensor 25.

The controller 26 performs a damping force control process described later using the input signals from the rotation angle sensor 24, the acceleration sensor 25, and the above-mentioned sensors, thereby controlling the electrode cylinders 16 and 17 with control signals. And an electric field having a magnitude corresponding to the control signal is generated between the electrode tubes 16 and 17. Thereby, the controller 26 changes the viscosity of the electrorheological fluid 6 between the electrode tubes 16 and 17 and variably controls the damping force of the rotary damper according to the driving state of the vehicle.

The rotary damper according to the present embodiment has the above-described configuration, and its operation will be described next.

First, when vibration from the road surface or the like acts on the casing 1 via a swing arm or the like of the vehicle, the rotating shaft 7 moves together with the movable vane 11 with respect to the casing 1 in a direction indicated by an arrow R1 in FIG. Is relatively displaced. As a result, the volume of each liquid chamber A1 decreases and the volume of each liquid chamber A2 increases, so that the electrorheological fluid 6 in each liquid chamber A1 flows through the flow holes 9
A, distribution chamber B1, liquid hole 12A, distribution chamber C and communication hole 1
6A, flows into the throttle passage 20, and from the throttle passage 20, the communication hole 17A, the flow chamber D, the communication path 13B, the flow chamber B2
And flows into each liquid chamber A2 through the flow holes 9B.

When the rotating shaft 7 is relatively rotated in the direction of arrow R2 in FIG. 4, the electrorheological fluid 6 in each liquid chamber A2 is rotated.
Flows through the flow chamber B2, the flow chamber C, the throttle passage 20, the flow chamber D, the flow chamber B1 and the like in the opposite direction to the respective liquid chambers A1.
Since a constant flow resistance is generated in the electrorheological fluid 6 by the damping valves 14 and 15 when flowing between the liquid chambers A 1 and A 2, a road surface is provided between the casing 1 and the rotating shaft 7. As a result, a damping force is generated against vibrations and the like, and the vibrations and the like can be buffered.

During the damping force control process by the controller 26, the electric field generated by the electrode tubes 16 and 17 causes
It is provided to the electrorheological fluid 6 within 0, and its viscosity changes according to the magnitude of the electric field. Thereby, the flow resistance when the electrorheological fluid 6 flows between the liquid chambers A1 and A2 increases or decreases, and the damping force of the rotary damper is adjusted.

Next, a damping force control process by the controller 26 will be described with reference to FIGS.

First, in step 1 in FIG. 6, initialization of a microcomputer or the like is performed to start the damping force control process, and a timer t provided in the microcomputer and a damping force correction calculation process described later are performed. Is cleared to zero.

Then, in step 2, since the damping force control process is performed every predetermined time T, it is determined whether or not the timer t has exceeded the time T.
It waits until the timer t becomes equal to or longer than the time T. Here, the time T is stored in advance in the storage unit 26A of the controller 26, and is set to a value of, for example, about 5 to 50 ms, preferably about 10 ms.

On the other hand, if "YES" is determined in the step 2, the process proceeds to the steps 3 to 7 to perform an arithmetic process for damping force control. Then, during the operation of the controller 26,
The processing of steps 3 to 7 is repeatedly executed at every time T.

Next, in step 3, a control signal such as a voltage corresponding to the command value S is calculated by using the command value S of the previous (the time T before) damping force calculated in steps 5 and 6 described later. Is applied between the electrode tubes 16 and 17.

Next, in step 4, input signals from the rotation angle sensor 24, the acceleration sensor 25 and other sensors are read in order to calculate the current damping force command value S. Then, in this case, the relative rotation angle θ between the casing 1 and the rotation shaft 7 is read from the rotation angle sensor 24, and the rotation angle Is calculated.

Next, in step 5, by using the relative speed v of the rotating shaft 7 in step 4 and the input signal from each sensor, the command of the damping force to be held by the rotary damper according to the driving state of the vehicle is provided. Calculate the value S. For example, when the vehicle is running at a high speed, turning, or the like, the command value S of the damping force is set large in order to keep the vehicle body stable against vibrations from the road surface and the like.

Thus, in the next step (after a lapse of time T), a control signal corresponding to the command value S is output to the electrode cylinders 16 and 17 so that the rotation between the rotating shaft 7 and the casing 1 is established. Generates a damping force substantially equal to the command value S, and the rotary damper appropriately buffers vibrations from the road surface and the like according to the driving state of the vehicle.

However, since the electrorheological fluid 6 becomes a Bingham fluid by applying an electric field in step 3, when the control signal corresponding to the command value S of the damping force is output in step 3, the rotating shaft 7 is thereafter rotated. When the relative rotation with respect to the casing 1 is started due to vibration from the road surface or the like, the actual damping force generated in the damper may temporarily become larger than the command value S due to the Bingham flow of the electrorheological fluid 6. .

Therefore, in step 6, damping force correction calculation processing is performed in steps 11 to 19 described later. And
In this damping force correction calculation processing, the rotating shaft 7 is
The command value S is temporarily reduced over a plurality of damping force correction calculation processes until a predetermined time has elapsed since the start of relative rotation with respect to.

Next, in step 7, it is determined whether or not it is time to end the damping force control process due to, for example, stopping the engine or the like.
In step 8, the damping force control processing ends. If "NO" is determined in the step 7, the timer t is cleared to zero in a step 9, and then the process returns to the step 2 and waits until a timing for performing the next arithmetic processing.

Next, the damping force correction calculation processing shown in FIG. 7 will be described. First, in step 11, the relative speed v of the rotating shaft 7 calculated in step 4 and the relative speed v stored in the storage unit 26A of the controller 26 are previously stored. By comparing with the determination value v0, it is determined whether the rotating shaft 7 is relatively stationary with respect to the casing 1. In this case, the judgment value v0 is
For example, when the relative speed v is set to zero or a small value of about 0.05 m / s and the relative speed v is equal to or less than the determination value v0, it can be determined that the rotating shaft 7 is substantially stationary with respect to the casing 1. It is.

Then, if "YES" is determined in the step 11, the counter N is first cleared to zero in a step 12. Here, the counter N is held at zero when the rotating shaft 7 is stationary, and when the rotating shaft 7 starts relative rotation, the counter N is incremented by "1" every time the damping force correction calculation processing is performed. You. The counter N increments until it becomes equal to a final value N0, which will be described later, and measures a fixed time determined by the final value N0 after the rotation shaft 7 starts relative rotation.

Next, at step 13, it is determined whether or not the damping force command value S is equal to or greater than the correction reference value S0. In this case, the correction reference value S0 is a reference value for determining whether or not the correction calculation of the command value S should be performed in step 14 described later, and is stored in the storage unit 26A of the controller 26 in advance.

When it is determined "YES" in step 13, the command value S of the damping force is relatively large.
If the actual damping force is larger than the command value S, the rigidity of the damper becomes too high. Further, when it is determined “NO” in step 13, since the command value S of the damping force is small, even if the actual damping force becomes larger than the command value S, the influence on the damping function of the damper is small. The process proceeds to step 15 described below without performing the above operation.

Next, in step 14, the damping force command value S is corrected by the following equation using the correction reference value S0 and the correction coefficient f (N) stored in the storage section 26A of the controller 26 in advance. Perform correction calculation.

[0050]

S = S0 × f (N)

Here, as shown by a characteristic line 27 in FIG. 8, when the counter N is incremented from zero to the final value N0, the correction coefficient f (N) is between 0 and 1 accordingly. Is a coefficient set to increase gradually. Immediately after the rotation shaft 7 starts to rotate relative to the casing 1, the initial value of the counter N is zero and f (0) becomes zero. The command value S thus set also becomes zero.

Next, at step 15, the counter N is incremented by “1” in order to perform the next damping force correction calculation process, and then the process returns to step 16. This allows
The counter N increases by “1” every time T.

On the other hand, if "NO" is determined in the step 11, the counter N is first started in the step 17 because the rotating shaft 7 has started to rotate relative to the casing 1 or is rotating relatively. It is determined whether it is equal to “255”. Here, “255” is a value that is set in the counter N when a certain time has elapsed from the start of the relative rotation. If this set value is larger than the final value N0, it is set to “255”. It is not limited.

If "YES" is determined in the step 17, the routine returns to the step 16 without performing a new correction operation since a fixed time has elapsed from the start of the relative rotation. If “NO” is determined in step 17, the process proceeds to step 18 because a fixed time has not elapsed since the start of the relative rotation.

Subsequently, at step 18, it is determined whether or not the counter N is equal to or smaller than the final value N0. In this case, the final value N0 determines the time during which the correction calculation of the command value S is continued from the start of the relative rotation, and is stored in the storage unit 26A of the controller 26 in advance, for example, as a value of about 5 to 20. .

If the determination at step 18 is "YES", since the correction calculation is being continued, the process returns after performing the correction calculation of the command value S at steps 13 to 16. As a result, the correction result of the command value S is calculated based on the correction coefficient f (N) from zero to the correction reference value S0 while the counter N is incremented from zero to the final value N0 in the damping force correction process repeated every time T. ) And increase slowly.

If the determination in step 18 is "NO", the counter N is larger than the final value N0.
It is determined that a predetermined time has elapsed from the start of the relative rotation, and the counter N is set to "255" in step 19, and the process returns in step 16.

Thus, in the present embodiment, the relative rotation displacement of the rotation shaft 7 with respect to the casing 1 is detected by the rotation angle sensor 24 and the acceleration sensor 25. When the relative rotation is started, the command value S of the damping force is temporarily reduced, so that when the rotation shaft 7 starts the relative rotation, the electrorheological fluid 6 is in the Bingham flow state. Even
The actual damping force generated in the damper can be reliably reduced.

That is, when the rotation shaft 7 starts relative rotation with respect to the casing 1, the relative rotation can be detected by the rotation angle sensor 24 and the acceleration sensor 25. The start can be reliably determined. When the command value S of the damping force is equal to or more than the correction reference value S0 in this state, the correction result of the command value S can be rapidly reduced by the first damping force correction calculation process from the start of the relative rotation. In particular, when the command value S is a large value equal to or more than the correction reference value S0, it is possible to reliably prevent vibrations and the like from the road surface from being easily transmitted to the vehicle body.

In the second and subsequent damping force correction calculation processing, the correction result of the command value S can be gradually increased from zero to the correction reference value S0, similarly to the characteristic line 27 shown in FIG. As a result, the damping force of the rotary damper can be gradually returned over a certain period of time.
Correction calculation of the command value S can be completed smoothly, sudden change in damping force during traveling can be reliably prevented, and vibrations and the like can be stably buffered by the rotary damper.

Therefore, according to the present embodiment, it is possible to prevent the damping force from becoming excessive at the start of operation of the rotary damper, to surely improve the riding comfort of the vehicle, and to enhance the reliability of the damper. Can be.

When the correction calculation of the command value S is completed, the counter N is set to "255". Therefore, once the correction result of the command value S returns to the correction reference value S0, the relative value of the rotation shaft 7 is reduced. As long as the rotation does not stop, the correction calculation of the command value S is not newly performed. As a result, the damping force correction calculation processing can be performed only within a certain period of time after the rotation shaft 7 starts the relative rotation. Unnecessary correction calculation can be prevented from being performed on the value S.

In the embodiment, step 11 in FIG. 7 shows a specific example of the displacement determination means, and step 14 shows a specific example of the electric field control means.

In the embodiment, the correction coefficient f (N)
Has been described as having the characteristic line 27 in FIG. 8, but the present invention is not limited to this, and an arbitrary characteristic line may be given to the correction coefficient f (N), and f (0) is set to a value other than zero. May be set to a value.

Further, in the embodiment, it has been described that the command value S of the damping force is temporarily reduced and then increased to the correction reference value S0, but the present invention is not limited to this, and the command value S is not limited to this.
May be gradually increased from zero or a value close to zero to the command value S.

Further, in the embodiment, at the start of the operation of the rotary damper, the command value S of the damping force is temporarily reduced by the equation (1) using the correction reference value S0 and the correction coefficient f (N). However, the present invention is not limited to this, and when the operation of the rotary damper starts, the command value S
As long as the command value S is temporarily reduced, the command value S may have an arbitrary decreasing characteristic.

Further, in the embodiment, the description has been made assuming that the rotating shaft 7 is mounted on the vehicle body side and the casing 1 is mounted on the wheel side. However, the present invention is not limited to this, and the rotating shaft 7 is mounted on the wheel side. Alternatively, the casing 1 may be attached to the vehicle body.

Further, in the embodiment, the rotary damper having the casing 1 and the rotating shaft 7 has been described as an example. However, the present invention is not limited to this.
The present invention may be applied to a damper using an electrorheological fluid similar to the reciprocating damper described in Japanese Patent No. 334 or the like.

Furthermore, in the embodiment, the case where the rotary damper is applied to a vehicle such as an automobile has been described as an example. However, the present invention is not limited to this, and may be applied to a motorcycle, a train, a ship, an aircraft, and the like. The present invention may be applied to agricultural machines, industrial machines, precision instruments, and the like.

[0070]

As described above in detail, according to the present invention, the damper is provided with the displacement detecting means, the displacement determining means, and the electric field control means. When the displacement is started, the relative displacement of the movable partition can be detected by the displacement detecting means, the start of the relative displacement can be reliably determined by the displacement determining means, and the electric field can be temporarily reduced by the electric field control means. Thereby, at the time of starting the operation of the damper, for example, even when the electrorheological fluid is in a Bingham flowing state, the actual damping force generated in the damper can be temporarily suppressed low. Thus, it is possible to prevent vibrations and the like from the road surface from being easily transmitted to the vehicle body, and it is possible to surely improve the riding comfort of the vehicle. When a certain period of time has elapsed after the start of the operation of the damper, the damping force of the damper can be smoothly increased, and the vibration and the like can be stably buffered by the damper, and the reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a rotary damper according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a control system of a rotary damper.

FIG. 3 is a vertical sectional view of the rotary damper as viewed from a direction indicated by arrows III-III in FIG. 1;

FIG. 4 is a sectional view as seen from the direction of arrows IV-IV in FIG. 3;

FIG. 5 is an enlarged view of a main part in FIG. 3;

FIG. 6 is a flowchart showing a damping force control process of a rotary damper.

FIG. 7 is a flowchart showing damping force correction calculation processing in FIG. 6;

FIG. 8 is a characteristic diagram showing a relationship between a correction coefficient and a counter.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 casing 6 electrorheological fluid 9 rotating cylinder (movable partition) 9A, 9B flow hole (flow path means) 11 movable vane (movable partition) 12, 13 valve seat member 12A, 13A liquid hole (flow path means) 12B, 13B Communication path (flow path means) 16, 17 Electrode cylinder (electric field applying means) 16A, 17A Communication hole (flow path means) 20 Restriction passage (flow path means) 24 Rotation angle sensor (displacement detection means) 26 Controller A1, A2 First and second liquid chambers B1, B2, C, D Flow chamber (flow path means)

Claims (1)

[Claims] 1. A casing accommodating an electrorheological fluid therein, a movable partition slidably provided in the casing, and defining first and second liquid chambers in the casing; A channel means for flowing an electrorheological fluid between the first and second liquid chambers when the liquid crystal slides relative to the casing; and Electric field applying means for applying an electric field to the electrorheological fluid; displacement detecting means for detecting relative displacement of the movable partition relative to the casing; and whether or not the movable partition has started relative displacement with respect to the casing in accordance with a detection signal from the displacement detecting means. And electric field control means for temporarily reducing the electric field applied to the electric field applying means when it is determined that the relative displacement has started by the displacement judgment means. Damper using viscous fluid.