JPH08223994A - Drive method of steeping motor for driving damping force characteristics modifying means - Google Patents

Abstract

PURPOSE: To prevent a stepping motor from stepping out due to hydraulic force while preventing increase of the system cost and deterioration of the system response. CONSTITUTION: The system comprises a stepping motor for modifying the damping force characteristics on the expanding and contracting sides by turning a rotary valve 14 stepwise to regulate the opening of variable restrictors R1 , R2 on the expanding and contracting sides, and means for controlling the drive speed of the stepping motor. The drive speed control means controls the drive speed of the stepping motor variably such that the hydraulic force of fluid flowing between first, second lateral holes 1a, 1b and a communication groove 14a on the contracting side or between third, fourth lateral holes 1c, 1d and a communication groove 14a on the expanding side and acting on the rotary valve 14 in the rotational direction thereof is increased during the stroke of a shock absorber SA among respective rotary positions of the rotary valve 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving method of a stepping motor for driving damping force characteristic changing means in a shock absorber of a vehicle.

[0002]

2. Description of the Related Art Conventionally, as a driving method of a stepping motor for driving a damping force characteristic changing means, for example, an actual opening 63
There is a "vehicle suspension" as described in Japanese Patent Publication No.-112914.

In this "vehicle suspension", a piston is provided which defines the inside of a cylinder into an upper chamber and a lower chamber, a piston rod (cylindrical member) with the piston attached to the lower end, and the piston. A rotary valve rotatably provided in the hollow portion of the rod, a port formed by penetrating the peripheral wall of the piston rod, and an outer periphery of the rotary valve matching the port,
A communication hole that forms a variable throttle portion with the port based on the rotation of the rotary valve, and a flow path that communicates between the upper chamber and the lower chamber via the port, the communication hole, and the hollow portion of the piston rod. In a shock absorber including a stepping motor that changes the damping force characteristic by adjusting the throttle opening degree of the variable throttle portion by rotating the rotary valve in steps, the target step TP obtained from the behavior of the vehicle and the current step Compare step CP, TP>
When CP is stepped up, when TP <CP is stepped down to step drive until the target step TP is reached. This step drive is always performed at a constant speed.

[0004]

However, the above-mentioned conventional driving method of the stepping motor for driving the damping force characteristic changing means has the following problems.

That is, the pre-initialized stepping motor is driven as described above. However, depending on the rotary position of the rotary valve, the fluid flowing between the port and the communication hole of the rotary valve is moved by the stroke of the shock absorber. May generate a fluid force to rotate the stepping motor in the direction opposite to the rotation direction of the stepping motor.Therefore, depending on the rotating position, the drive torque loses the fluid force, causing the stepping motor to step out and be initialized. The wrong position will go wrong. As a result, the subsequent positioning becomes erratic, and the damping force characteristic control of the shock absorber according to the behavior of the vehicle cannot be performed, which may impair the running stability and the riding comfort of the vehicle.

With respect to the above problems, by driving the stepping motor at a low speed, the driving torque of the stepping motor can be increased, and thus, it is also possible to prevent step-out during the action of fluid force. But,
Since the driving speed of the stepping motor during the step driving is always constant, if the driving speed is uniformly low, the system responsiveness is sacrificed, and another problem that the control according to the vehicle behavior cannot be performed occurs. Although it is possible to solve the above problems by increasing the driving torque of the stepping motor, the system cost will be increased.

The present invention has been made by paying attention to the above-mentioned conventional problems, and prevents the stepping motor from being out of step due to fluid force while preventing the system cost from rising and the system response from decreasing. An object of the present invention is to provide a driving method of a stepping motor for driving a damping force characteristic changing means that can be performed.

[0008]

In order to achieve the above object, the driving method of the damping force characteristic changing means driving stepping motor according to the first aspect of the present invention is provided such that the inside of the cylinder is divided into two chambers. A valve body, a tubular member provided on the valve body, a rotary valve rotatably provided in a hollow portion of the tubular member, and a port formed by penetrating a peripheral wall of the tubular member, A communication groove formed on the outer circumference of the rotary valve that matches the port and forming a variable throttle portion with the port based on the rotation of the rotary valve, and the two chambers through the port and the communication groove. A flow path and a stepping motor that changes the damping force characteristic by adjusting the throttle opening of the variable throttle part by rotating the rotary valve stepwise, and the driving of the stepping motor. And a drive speed control means capable of controlling the degree of rotation of the rotary valve, wherein the drive speed control means causes the fluid flowing between the port and the communication groove to move relative to the rotary valve according to the stroke of the shock absorber among the rotary positions of the rotary valve. According to the means, the driving speed of the stepping motor is variably controlled to be reduced in accordance with the increase of the fluid force acting in the rotation direction.

According to a second aspect of the present invention, in the driving method of the stepping motor for driving the damping force characteristic changing means, the driving speed control means stores the number of steps by which the stepping motor is driven, and the stepping motor is indexed based on this storage. Further, the fluid force corresponding to the rotational position of the rotary valve is obtained, and at the rotational position where the fluid force becomes large, the driving speed of the stepping motor is variably controlled to be decreased.

According to a third aspect of the present invention, in the driving method of the stepping motor for driving the damping force characteristic changing means, the driving speed control means stores the number of steps of driving the stepping motor, and the step number is calculated based on this storage. The direction of the fluid force corresponding to the rotary position of the rotary valve and the direction of the fluid force acting on the rotary valve are obtained, and when the direction of the fluid force opposes the direction of rotation of the stepping motor at the rotary position where the fluid force increases. Only the means for variably controlling the driving speed of the stepping motor is used.

[0011]

In the driving method of the stepping motor for driving the damping force characteristic changing means according to the first aspect of the present invention, as described above, the flow between the port and the communication groove is caused by the stroke of the shock absorber in each rotational position of the rotary valve. The fluid to be rotated is variably controlled in a direction to reduce the driving speed of the stepping motor at the time of driving according to the magnitude of the fluid force acting on the rotary valve in the rotation direction, that is, when the fluid force does not act The motor is driven at normal speed, which prevents the system cost from rising and the system responsiveness from decreasing, and, conversely, when fluid force acts,
The stepping motor is controlled so as to decrease the driving speed of the stepping motor in accordance with the magnitude of the fluid force, which increases the driving torque and prevents the stepping motor from being out of step due to the fluid force.

Further, according to the second aspect, the number of steps for driving the stepping motor is stored, and the fluid force corresponding to the rotary position of the rotary valve, which is indexed based on this memory, is obtained.

Further, in the third aspect, the direction is required in addition to the fluid force acting on the rotary valve, and when the direction of the fluid force opposes the rotation direction of the stepping motor at the turning position where the fluid force becomes large. It is variably controlled to reduce the driving speed of the stepping motor, so that even if the fluid force is large, the normal driving speed can be maintained when the direction of the fluid force matches the rotation direction of the stepping motor. , The decrease in responsiveness is suppressed to a minimum.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. (First Embodiment) FIG. 2 is a partially cutaway cross-sectional view showing a damping force characteristic type shock absorber SA to which a driving method of a damping force characteristic changing means driving stepping motor of a first embodiment of the present invention is applied. As shown in this figure, the shock absorber SA of variable damping force characteristic type includes a cylinder 2, a piston P defining the inside of the cylinder 2 into an upper chamber A and a lower chamber B, and a reservoir chamber on the outer periphery of the cylinder 2. An outer cylinder 11 that forms C, a base 17 that defines a lower chamber B and a reservoir chamber C, a guide member 18 that guides the sliding of the piston rod 1 connected to the piston P, the outer cylinder 11, and the vehicle body. A suspension spring 19 and a bumper bar 20 which are interposed between the piston rod 1 and the rotary valve 14 which constitutes a damping force characteristic changing means. The shock absorber SA stepping motor 21 for driving the step rotating the rotary valve 14 through the control rod 15 to the upper end of the
Has a structure attached.

Next, FIG. 1 is an enlarged sectional view showing the structure of the piston P portion of the shock absorber SA. This piston P is composed of a piston body (valve body) 3 and a pressure side installed in series above and below the piston body (valve body) 3. The piston body 3 includes a sub body 4 and an extension side sub body 5.
A piston ring 6 that seals slidably with the cylinder 2 is mounted on the outer peripheral surface of the.

As shown in detail in FIGS. 3 and 4, the piston body 3 has a pressure side communicating hole 3a for ensuring a flow from the lower chamber B to the upper chamber A and an upper chamber A to the lower chamber. Four expansion side communication holes 3b for ensuring the flow in the B direction are provided alternately in the circumferential direction, and the piston body 3
A pressure side seat surface 3c that forms a pressure side intermediate pressure receiving chamber 3e that communicates with the pressure side communication hole 3a is formed to project from the upper surface of the, and a lower surface of the piston body 3 that communicates with the extension side communication hole 3b. The extension side seat surface 3d forming 3f is formed to project. A compression side high damping valve 7 that abuts on the compression side seat surface 3c and allows the flow of the compression side communication hole 3a in a restricted manner is provided on the upper surface of the piston body 3, and the expansion side seat is provided on the lower surface of the piston body 3. An expansion-side high damping valve 8 is provided which abuts on the surface 3d and allows the flow of the expansion-side communication hole 3b to be restricted.

A pressure side pressure receiving chamber 4a is formed on the upper surface of the pressure side sub-body 4, and a pressure side seat surface 4b is formed in a protruding manner.
A pressure side low damping valve 9 is provided in contact with the pressure side seat surface 4b. Further, an expansion side pressure receiving chamber 5a is formed on the lower surface of the expansion side sub-body 5 to form an expansion side seat surface 5b, and an expansion side low damping valve 10 is provided in contact with the expansion side seat surface 5b. ing.

The piston rod 1 has washers 12a, 12 to allow the valves 7, 8, 9, 10 to bend in the valve opening direction and to keep the amount of deflection to a predetermined amount.
b, 12c, 12d and retainers 13a, 13b are provided.

A substantially cylindrical rotary valve 14 is rotatably inserted into a through hole 1e formed through the piston rod 1 in the axial direction. The rotary valve 14 is radially opposed to the outer circumference of the rotary valve 14. And the pressure side communication grooves 14a, 14a formed in the axial direction and the piston rod 1 respectively.
The pressure side high damping valve 7 is bypassed by the first lateral hole (port) 1a and the second lateral hole (port) 1b formed in the radial direction, and the pressure side intermediate pressure receiving chamber 3e formed in the upper end surface of the piston body 3. And a compression-side bypass flow path II that communicates between the compression-side communication hole 3a and the upper chamber A. Also, the expansion-side communication grooves 14b are formed on the outer circumference of the rotary valve 14 in the axial direction so as to face each other in the radial direction. , 14b, the third lateral hole (port) 1c and the fourth lateral hole (port) 1d formed in the piston rod 1 in the radial direction, and the expansion side intermediate pressure receiving chamber 3f formed in the lower end surface of the expansion side sub-body 5, An expansion side bypass flow passage I is formed that bypasses the expansion side high damping valve 8 and communicates between the expansion side communication hole 3b and the lower chamber B.

A pressure side variable aperture R ₂ is formed between the pressure side communication groove 14a and the first lateral hole 1a and the second lateral hole 1b, and the extension side communication groove 14b, the third lateral hole 1c and the third lateral hole 1c. The expansion side variable diaphragm R ₁ is formed between the four lateral holes 1d and the diaphragm opening can be independently changed by rotating the rotary valve 14. The rotary valve 14 has a through hole 1e as described above.
A control rod 15 extending inward is connected so that the driving force from the stepping motor 21 can be input. Also, at the lower position of the rotary valve 14,
A retaining plug 16 is provided by being fitted into the through hole 1e.

In the present embodiment, because of the above-mentioned structure, the upper chamber A is used as the flow passage through which the fluid can flow in the extension stroke.
From the expansion side communication hole 3b to the expansion side intermediate pressure receiving chamber 3f, and the expansion side high damping valve 8 is opened at that position to flow into the lower chamber B, and the expansion side main flow path D and the expansion side. The extension side high damping valve 8 is bypassed from the communication hole 3b, and the extension side bypass flow path I
There is an expansion side sub-flow path E that opens the expansion side low damping valve 10 and flows into the lower chamber B through, and as a flow path through which the fluid can flow in the pressure stroke, the lower chamber B is connected to the compression side communication. The pressure-side high damping valve 7 is placed at the position of the pressure-side intermediate pressure receiving chamber 3e via the hole 3a.
To bypass the pressure side main flow path F flowing into the upper chamber A and the pressure side high damping valve 7 from the pressure side communication hole 3a, and to open the pressure side low damping valve 9 through the pressure side bypass flow path II. There is a pressure side auxiliary flow path G flowing into the chamber A.

Further, the rotary valve 14 has three damping force characteristic positions (HS characteristic position, SS characteristic position,
It is possible to switch to any position within the range of SH characteristic position). 7 shows the damping force characteristic switching characteristic and the opening / closing state of each flow path D, E, F, G.

First, at the SS characteristic position of FIG. 5 (of FIG. 7), the expansion side variable aperture R ₁ and the compression side variable aperture R ₂ are all open, and as shown in the SS column of FIG. Side main flow path D, extension side sub flow path E, pressure side main flow path F, pressure side sub flow path G
Are all available for distribution. Therefore, during the extension stroke, in the low piston velocity range, the fluid flows through the extension side sub-channel E with a small flow resistance, and when the piston velocity increases, the fluid flows through the extension side main channel D, whereby the damping force of the extension stroke is generated. The characteristics are soft. Further, during the pressure stroke, in the low piston velocity range, the fluid flows through the pressure side sub-flow passage G with a small flow resistance, and when the piston velocity increases, the fluid flows through the pressure side main flow passage F,
As a result, the damping force characteristic of the pressure stroke becomes soft (SS characteristic).

Further, in the HS characteristic position of FIG. 5 (of FIG. 7), the pressure side variable throttle R ₂ is opened and the expansion side variable throttle R ₁ is opened.
Is closed, and only the expansion side main flow path D, the compression side main flow path F, and the compression side sub flow path G are allowed to flow, as shown in the H-S column of FIG. Therefore, the damping force characteristic of the compression stroke is in the soft state, but the damping force characteristic of the extension stroke is in the hard state (HS characteristic).

Further, in the SH characteristic position of FIG. 5 (of FIG. 7), contrary to the above, the expansion side variable restrictor R ₁ is opened and the pressure side variable restrictor R ₂ is closed. As shown in, only the compression side main flow path F, the expansion side main flow path D, and the expansion side sub flow path E are allowed to flow. Therefore, the damping force characteristic of the extension stroke is in the soft state, but the damping force characteristic of the pressure stroke is in the hard state (SH characteristic).

From the SS characteristic position of FIG. 5, HS
When the rotary valve 14 is stepwise rotated counterclockwise in order to switch to the characteristic position direction, the throttle opening of the expansion side variable throttle R ₁ is narrowed and the flow passage cross-sectional area of the expansion side auxiliary flow passage E is reduced. Therefore, only the damping force characteristic of the extension stroke gradually increases while the pressure stroke remains soft (HS characteristic area).

Also, from the SS characteristic position of FIG.
When the rotary valve 14 is rotated stepwise in the clockwise direction to switch to the characteristic position direction, the throttle opening of the pressure side variable throttle R ₂ is narrowed and the flow passage cross-sectional area of the pressure side auxiliary flow passage G is reduced. Therefore, the damping force characteristic of the compression stroke gradually increases while the extension stroke remains soft (SH characteristic region).

Next, the structure of the control unit for controlling the damping force characteristic of the shock absorber SA will be described with reference to the system block diagram of FIG. 8. In the figure, 22 is a control unit. , The interface circuit 22a,
It has a CPU 22b and a drive circuit 22c.

Then, the interface circuit 22a
The signals from the sprung vertical acceleration sensor (G sensor) 23, the steering sensor 24, the vehicle speed sensor 25, and the brake sensor 26 are input to the CPU 22b.
Then, a control signal for optimally controlling the damping force characteristic of each shock absorber SA in the vehicle is obtained based on each signal from the interface circuit 22a, and
Based on this control signal, a step drive signal for step-driving the stepping motor 21 in each shock absorber SA to the target step position (target rotation position of the rotary valve 14) is the drive circuit 2 described above.
2c is output.

Since the stepping motor 21 can be open-controlled and the step position of the stepping motor 21 (rotational position of the rotary valve 14) can be stored in the CPU 22b, if the stepping motor 21 is initialized in advance. The drive speed of the stepping motor 21 is variably controlled according to the fluid force acting on the rotary valve 14 at the turning position at that time.

That is, the fluid force means, for example, in the pressure stroke of the shock absorber SA, the pressure side bypass passage II.
When the fluid passes between the second lateral hole 1b forming the pressure side variable throttle R ₂ and the pressure side communication groove 14a of the rotary valve 14, the rotary valve 14 is rotated depending on the throttle opening of the variable throttle R _2. It is the force of the fluid that acts in the direction that causes it. That is, as shown in (b), (c) in FIG. 9, the variable throttle R ₂
In the state in which the narrowing is not performed, the direction of the fluid flowing from the second lateral hole 1b into the pressure side communication groove 14a is in the axial direction of the rotary valve 14, so that the fluid force for rotating the rotary valve 14 does not act. But in Figure 9
As shown in (a) and (d), when the variable throttle R ₂ is narrowed down, the direction of fluid flow is inclined toward the direction of rotation of the rotary valve 14, so the rotary valve 14 is rotated. The fluid force indicated by the dotted arrow acts in the direction of the action.

Therefore, as described above, the rotation position of the rotary valve 14 is detected from the step position of the stepping motor 21 stored in the CPU 22b, and a driving torque larger than the fluid force acting at each rotation position is generated. First, the drive speed is set for each rotational position. That is, the solid line in FIG. 10 indicates the rotational positions (−6 to −6) of the rotary valve 14 during the pressure stroke.
0-10) shows the change characteristics of the fluid force acting on the rotary valve 14, and the dotted line in FIG. 10 shows the target drive torque of the stepping motor 21 at each rotational position that can oppose each fluid force shown by the solid line. ing.
Then, FIG. 11 shows the drive speed of the stepping motor 21 corresponding to the target drive torque, and based on both of the above characteristics, as shown in Table 1, the rotary positions of the rotary valve 14 (-6 to 0 to 0). The driving speed in 10) is variably set. That is, in this embodiment, the drive speed control means in the claims is incorporated in the CPU 22b.

[0033]

[Table 1]

The drive circuit 22c outputs the drive signal controlled to the drive speed set as described above.
A drive signal is output to the drive circuit 22c, and each stepping motor 21 is driven by the drive circuit 22c.

Next, the contents of drive control of the stepping motor 21 will be described with reference to the flowchart of FIG.

First, in step 101, the timer count TCNT is incremented by 1, and then the following step 1
In 02, it is determined whether the timer count TCNT has counted up to the set driving speed data T1.
If S, the process proceeds to step 103, and if NO, this ends one flow.

In step 103, the current step CP and target step TP of the stepping motor 21 are set.
Read out. In the following step 104, the current step CP of the stepping motor 21 is revised to drive speed data T1 corresponding to the rotational position of the rotary valve 14 as shown in Table 1 above.

In the following step 105, it is judged whether or not the target step TP is larger than the current step CP in the stepping motor 21, and YES (TP> C)
If P), go to step 106 and present step C
After stepping up from P by one step, the process proceeds to step 110. If NO, the process proceeds to step 107.

In step 107, it is judged whether or not the current step CP in the stepping motor 21 is not the same as the target step TP. If YES (TP <CP), the routine proceeds to step 108, where 1 is subtracted from the current step CP.
After stepping down, go to step 110,
If NO (TP = CP), the process proceeds to step 109.

In step 109, the timer count TCNT and the driving speed data T1 are cleared, and then the process proceeds to step 110. In step 110, the excitation pattern of the stepping motor 21 is set from the current step CP, and in the subsequent step 111, the excitation pattern is set. The pattern is output to the stepping motor 21, and the step 10
The stepping motor 21 is driven at a speed based on the driving speed data T1 revised in 4, and the one-time flow is completed. After that, the above flow is repeated.

As described above, according to the method of driving the stepping motor of this embodiment, the driving speed of the stepping motor 21 is controlled as high as possible at the rotation position where the fluid force does not act during driving. As a result, while the system responsiveness is improved, the drive position is variably controlled in the direction in which the drive speed of the stepping motor 21 is decreased according to the strength of the fluid force at the rotational position where the fluid force acts. By increasing the torque, it is possible to prevent stepping out of the stepping motor 21 due to the fluid force.

(Second Embodiment) Next, a second embodiment of the present invention will be described. In addition, in this embodiment, the stepping motor 21 is included in the control contents of the control unit 4.
Since the contents of the drive control of (1) are different from those of the first embodiment, and other configurations are almost the same as those of the first embodiment, only the differences will be described.

FIG. 13 is a flow chart showing the drive control contents of the stepping motor 21 in this embodiment. First, at step 201, the timer count TCN is set.
After T is counted up by 1, in the subsequent step 202, it is determined whether or not the timer count TCNT has counted up to the set drive speed data T1. If YES, the process proceeds to step 203, and if NO, this End the flow of times.

In step 203, the current step CP and target step TP of the stepping motor 21 are set.
Read out. In the following step 204, it is determined whether or not the target step TP is larger than the current step CP in the stepping motor 21, and if NO, the process proceeds to step 205. Then, in step 205, it is determined whether or not the current step CP in the stepping motor 21 is the same as the target step TP, and NO (T
When P = CP), the routine proceeds to step 206, where the timer count TCNT and the driving speed data T1 are cleared and then the routine proceeds to step 212. And this step 21
2, the stepping motor 2 from the current step CP
The excitation pattern of 1 is set, and in the following step 213,
The excitation pattern is output to the stepping motor 21, and this completes one flow.

YES in step 204 (TP> C
If it is determined to be P), the process proceeds to step 207, and the current step CP is increased by one step, and then step 2
Go to 08. Then, in this step 208, it is judged whether or not the direction of the fluid force acting on the rotary valve 14 in the current step CP is the direction opposite to the step-up direction, and if NO, the process directly proceeds to step 212. If YES, the process proceeds to step 211, and the current step CP of the stepping motor 21 is revised to drive speed data T1 corresponding to the rotational position of the rotary valve 14 as shown in Table 1 above. Then, the process proceeds to step 212.

YES in step 205 (TP <C
If it is determined to be P), the process proceeds to step 209, and the current step CP is lowered by one step, and then step 2
Go to 10. Then, in this step 210, it is determined whether or not the direction of the fluid force acting on the rotary valve 14 in the current step CP is the direction opposite to the step-down direction. If NO, the process directly proceeds to step 212. If YES, the process proceeds to step 211, and the current step CP of the stepping motor 21 is revised to drive speed data T1 corresponding to the rotational position of the rotary valve 14 as shown in Table 1 above. Then, the process proceeds to step 212.

After that, the above flow is repeated.

That is, in this embodiment, the drive speed control means of the control unit 4 stores the number of steps for driving the stepping motor 21 and corresponds to the rotary position of the rotary valve 14 which is indexed based on this memory. The direction of the fluid force acting on the rotary valve 14 and the direction of the fluid force acting on the rotary valve 14 are obtained, and only when the direction of the fluid force opposes the direction of rotation of the stepping motor 14 at the turning position where the fluid force becomes large,
Therefore, even if the fluid force is large, the normal drive speed is maintained when the direction of the fluid force matches the direction of rotation of the stepping motor 21. Therefore, in addition to the effect of the first embodiment, it is possible to obtain the effect that the deterioration of the system responsiveness can be suppressed to a minimum.

The embodiment has been described above with reference to the drawings. However, the specific configuration is not limited to this embodiment, and the present invention is applicable even if there are design changes and the like without departing from the gist of the present invention. include.

For example, in the embodiment, the case where the valve body is formed of the piston body is taken as an example, but the present invention can be applied to the case where the valve body is formed of other base bodies. The magnitude of the fluid force changes depending on the rotating position as in the present embodiment, and also changes depending on the flow rate of the variable throttle portion. Therefore, the drive speed may be changed according to the piston speed (relative speed between sprung and unsprung).

[0051]

As described above, in the driving method of the stepping motor for driving the damping force characteristic changing means according to the first aspect of the present invention, the step of the shock absorber in each rotational position of the rotary valve is used. The fluid flowing between the port and the communication groove is variably controlled so as to reduce the driving speed of the stepping motor according to the magnitude of the fluid force acting on the rotary valve in the rotation direction. It is possible to obtain an effect that it is possible to prevent stepping out of the stepping motor due to fluid force while preventing soaring and lowering of system responsiveness.

Further, in the driving method of the stepping motor for driving the damping force characteristic changing means according to the third aspect, the driving speed control means stores the number of steps of driving the stepping motor, and based on this storage. The direction of the fluid force corresponding to the determined rotary position of the rotary valve and the direction of the fluid force acting on the rotary valve are obtained, and at the rotary position where the fluid force increases, the direction of the fluid force is the direction of rotation of the stepping motor. Even if the fluid force is large, the normal drive speed is maintained when the direction of the fluid force matches the direction of rotation of the stepping motor, by variably controlling the drive speed of the stepping motor only when facing. Because it can be
In addition to the effect of the first aspect of the present invention, it is possible to obtain the effect that it is possible to suppress the decrease in system responsiveness to a minimum.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an essential part of a damping force variable type shock absorber to which a driving method of a damping force characteristic changing means driving stepping motor of a first embodiment of the present invention is applied.

FIG. 2 is a partially cutaway cross-sectional view showing an entire damping force characteristic type shock absorber to which the driving method of the damping force characteristic changing means driving stepping motor of the first embodiment of the present invention is applied.

FIG. 3 is a plan view of a piston body of the shock absorber of the first embodiment.

FIG. 4 is a bottom view of the piston body of the shock absorber of the first embodiment.

FIG. 5 is a cross-sectional explanatory view for explaining the operation of the rotary valve in the shock absorber of the first embodiment.

FIG. 6 shows the HS characteristics of the shock absorber of the first embodiment,
FIG. 4 is a cross-sectional view showing a fluid flow with SS characteristics and SH characteristics.

FIG. 7 is a diagram showing the damping force characteristic switching characteristic of the shock absorber of the first embodiment and the open / closed state of each flow path.

FIG. 8 is a system block diagram showing a configuration of a control unit in a damping force variable shock absorber to which the driving method of the damping force characteristic changing means driving stepping motor of the first embodiment of the present invention is applied.

FIG. 9 is an enlarged sectional view of an essential part for explaining a fluid force acting on a rotary valve in a damping force variable shock absorber to which a driving method of a damping force characteristic changing unit driving stepping motor of a first embodiment of the invention is applied. Is.

FIG. 10 is a diagram illustrating a damping force variable type shock absorber to which the driving method of the damping force characteristic changing unit driving stepping motor according to the first embodiment of the present invention is applied, and the flow acting on the rotary valve at each rotary position of the rotary valve during the pressure stroke. It is a characteristic view which shows the target drive torque corresponding to a physical force and a fluid force.

FIG. 11 is a characteristic diagram showing a driving torque corresponding to a driving speed of a stepping motor in a damping force variable type shock absorber to which the driving method of the damping force characteristic changing means driving stepping motor of the first embodiment of the present invention is applied.

FIG. 12 is a flow chart showing the drive control contents of the stepping motor in the variable damping force type shock absorber to which the driving method of the damping force characteristic changing means driving stepping motor of the first embodiment of the present invention is applied.

FIG. 13 is a flow chart showing the drive control content of the stepping motor in the variable damping force type shock absorber to which the driving method of the damping force characteristic changing means driving stepping motor of the second embodiment of the present invention is applied.

[Explanation of symbols]

SA Shock absorber A Upper chamber B Lower chamber R ₁ Extension side variable throttle (variable throttle section) R ₂ Pressure side variable throttle (variable throttle section) I Extension side bypass flow path II Pressure side bypass flow path 1 Piston rod (cylindrical member) 1a 1st lateral hole (port) 1b 2nd lateral hole (port) 1c 3rd lateral hole (port) 1d 4th lateral hole (port) 2 Cylinder 3 Piston body (valve body) 14 Rotary valve 14a Pressure side communicating groove 14b Extension side Communication groove 21 Stepping motor

Claims (3)

[Claims] 1. A valve body having a cylinder defined by two chambers, a tubular member provided on the valve body, and a rotary valve rotatably provided in a hollow portion of the tubular member. And a port formed by penetrating the peripheral wall of the tubular member and a communication which is formed on the outer periphery of a rotary valve matching the port and forms a variable throttle portion with the port based on rotation of the rotary valve. Stepping for adjusting damping force characteristics by adjusting the throttle opening of the variable throttle unit by stepwise rotating the rotary valve and the groove, the flow path communicating between the two chambers via the port and the communication groove. A motor and a drive speed control means capable of controlling the drive speed of the stepping motor are provided, and the drive speed control means controls the rotation position of the rotary valve. According to the stroke of the absorber, the fluid flowing between the port and the communication groove is variably controlled to decrease the driving speed of the stepping motor in accordance with the increase of the fluid force acting on the rotary valve in the rotation direction. A driving method of a stepping motor for driving a damping force characteristic changing means. 2. The drive speed control means stores the number of steps for driving the stepping motor, obtains a fluid force corresponding to the rotary position of the rotary valve which is indexed based on the stored memory, and the fluid force is calculated. 2. The method of driving a stepping motor for driving damping force characteristic changing means according to claim 1, wherein the driving speed of the stepping motor is variably controlled to decrease in accordance with the increase. 3. The drive speed control means stores the number of steps for driving the stepping motor, and the fluid force corresponding to the rotary position of the rotary valve indexed based on this memory and the flow acting on the rotary valve. The direction of the physical force is obtained, and at the turning position where the fluid force becomes large, the variable control is performed so as to reduce the driving speed of the stepping motor only when the direction of the fluid force faces the rotation direction of the stepping motor. The driving method of a stepping motor for driving the damping force characteristic changing means according to claim 1 or 2.