JPH0516637A - Attenuator - Google Patents

Abstract

PURPOSE:To obtain an optimum damping force without delay to the road surface condition a vehicle is passing, by controlling the damping force by using a predicted stroke signal of at least at the end of the control delay time. CONSTITUTION:A control signal to generate an optimum damping force depending on the stroke signal of a piston 30 is found in an attenuator 24, and damping force is controlled by the control signal. In this case, a CPU 82 predicts the stroke signal of the attenuator 24 at least at the end of the control delay time by using the detected stroke signal. And the CPU 82 controls the damping force by using the predected stroke signal. Consequently, an optimum damping force to the road surface condition the vehicle is passing can be obtained with no delay.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a damper for controlling a damping force based on at least one of a stroke position and a stroke speed of a piston.

[0002]

BACKGROUND OF THE INVENTION In vehicles such as automobiles and motorcycles, it is desirable to be able to change the damping force according to running conditions. Therefore, the applicant proposes one that detects the expansion / contraction amount (stroke) or expansion / contraction speed of a cushion unit in which a damper and a coil spring are integrated, and controls the opening / closing of an oil passage provided in the piston of the damper by a linear solenoid. (See, for example, Japanese Patent Application No. 1-1233).

The attenuator used here includes a piston that defines two main oil chambers in a cylinder, and a switching valve that is provided in the piston and defines first and second auxiliary oil chambers in the piston. And an orifice interposed between the first and second sub oil chambers to guide the hydraulic pressure of the high pressure side main oil chamber to the first sub oil chamber,
When the pressure in the second sub-oil chamber exceeds the pressure set by the linear solenoid, the pressure in the second sub-oil chamber is reduced, and the switching valve is moved by the difference in the internal pressures in the two sub-oil chambers so that the pressure between the two main oil chambers is increased. The oil passage is opened to control the damping force.

According to this attenuator, it is possible to freely set the damping characteristic during expansion or contraction of the attenuator by changing the exciting current of the linear solenoid.
However, in the case of using this attenuator, conventionally, the optimum damping force was obtained by using the detected values of the stroke position and stroke speed of the piston, and then the exciting current of the linear solenoid was obtained. Therefore, there is a time delay between the time when the stroke position / speed is detected and the time when the damping force is generated with respect to this detected value. In other words, the damping force for the passing road surface is set with a delay, and the optimum damping force for the passing road surface cannot be obtained.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an attenuator capable of obtaining an optimum damping force without delaying the road surface condition during passage. To do.

[0006]

According to the present invention, an object of the present invention is to obtain a control signal for generating an optimum damping force on the basis of a stroke signal including at least one of a stroke position and a stroke speed of a piston, and to obtain a damping signal by this control signal. In the attenuator for controlling the force, using the detected stroke signal, a predictive calculation means for predicting the stroke signal at least a control delay time ahead of the attenuator is provided, and the damping force is calculated using the predicted stroke signal. Achieved by an attenuator characterized by controlling.

[0007]

1 is a conceptual diagram showing an embodiment in which the present invention is applied to a motorcycle, FIG. 2 is a sectional view showing a cushion unit for rear wheel suspension, and FIG. 3 is an explanatory view of the principle of a stroke sensor thereof. is there.

In FIG. 1, reference numeral 10 is a body frame, 1
2 is an engine, 14 is a fuel tank, and 16 is an operating seat. 18 is a rear arm, the front end of which is the engine 1
It is connected to the body frame 10 in the vicinity of the rear of 2 so as to be vertically swingable. A rear wheel 20 is provided at the rear end of the rear arm 18.
Is held. The output of the engine 12 is transmitted to this rear wheel 20 by a chain (not shown).

Reference numeral 22 denotes a cushion unit, which is a combination of a cylindrical attenuator 24 and a coil spring 26, which are integrated. This attenuator 24 has the structure disclosed in Japanese Patent Application No. 1-1233. An upper end of the cushion unit 22 is pivotally supported by a pin on a cross member suspended on a seat rail (not shown) that supports the driving seat 16, and a lower end thereof is pivotally supported by the rear arm 18 by a pin.

The attenuator 24 includes a cylinder 18 axially supported on the rear arm 18, a piston 30 sliding in the cylinder 28, and a piston rod 32 connected to the piston 30 and extending upward. An upper bracket 34 is fixed to the upper end of the piston rod 32, and is pivotally supported on the seat rail side. 36 and 38 are caps attached to the upper opening of the cylinder 28,
The piston rod 32 penetrates the caps 36 and 38.

Seals 40 and 42, which are in close contact with the cylinder 28 and the piston rod 32, are attached to the lower cap 36. Linear solenoid 4 on piston 30
4 are accommodated. The oil chamber below the cylinder 28 is connected to a reservoir (not shown) by a pipe 46.

The stroke sensor used in this embodiment uses the Wiedemann effect. The effect is that a magnetic field (longitudinal magnetic field) is applied to a magnetic rod (magnetostrictive rod) in the longitudinal direction.
This is a phenomenon in which the rod is twisted when a magnetic field in the circumferential direction (circular magnetic field) is applied at the same time. Next, this phenomenon will be described.

In FIG. 3, reference numeral 50 denotes a magnetic cylindrical rod, which is the rod portion of the present invention. This magnetic rod 5
A conducting wire 52 is passed over the center line of 0 while being insulated from the rod 50. One end of this conductor is a DC pulse power source 54
, And the other end is grounded. Therefore, the pulse passing through the lead wire 52 forms a circumferential magnetic field M _{C on} the cylindrical rod 50. Reference numeral 56 is a permanent magnet that serves as an annular portion of the present invention, and the rod 50 is inserted through the circular hole of the magnet 56. The magnet 56 is a magnetic field that passes through the hole, that is, a magnetic field M _L in the lengthwise direction of the bar 50.

Therefore, a helical magnetic field is locally generated in a portion where the two magnetic fields M _L and M _C are superposed, and as a result, local twist, that is, distortion is generated by the Wiedemann effect. This distortion propagates through the magnetic rod 50 toward both ends, one of which is absorbed by the elastic wave absorber 58, and the other is detected by the pickup 60 as an electric pulse. The pickup 60 includes, for example, a permanent magnet, movable levers 64 and 64 that sandwich the magnet, and the levers 64 and 64.
And a coil 66 wound around the
The tips of Nos. 4 and 64 are fixed to the outer peripheral surface of the magnetic rod 50.

Therefore, when the elastic strain generated in the magnetic rod 50 is transmitted to the lever 64 of the pickup 60, the coil 66 vibrates together with the lever 64 and outputs an electric pulse. After the pulse current used as the trigger for generating this elastic wave is output from the pulse power supply 54, the pickup 6
The delay time until 0 detects an electric pulse is measured by the position detection circuit 68, and the position of the permanent magnet 56 can be determined from this delay time.

In this embodiment, the piston rod 32 is made of a non-magnetic material such as aluminum, copper, brass and ceramics in the shape of a pipe, and the magnetic rod 50 is inserted and accommodated therein. On the other hand, the annular permanent magnet 56 is the cap 3
I attached it to 8. The upper bracket 34 at the upper end of the piston rod 32 holds a pickup 60 connected to the upper end of the magnetic rod 50.

As described above, the stroke sensor is used as the permanent magnet 5.
When the position 6 is detected, that is, the stroke position of the attenuator 24, the position signal p is detected by the low-pass filter (LPF).
It is input to the CPU 82 via 80. The CPU 82
First, in the lever ratio correction means 84, this position signal p ₀
From the swing amount of the rear arm 18 and the cushion unit 22
The ratio of the expansion / contraction amount, that is, the lever ratio is corrected. CPU8
In the case of 0, the speed detection means 86 time-differentiates the corrected stroke position signal p to obtain the stroke speed v of the piston 30. Further, the direction discriminating means 88 obtains the expansion / contraction direction from the positive / negative of this time derivative.

In the present invention, the position P and the speed V after the elapse of the predetermined time Δt are calculated and calculated based on the stroke position p and the stroke speed v. This time Δt is at least a time corresponding to the operation delay of this attenuator. Various mathematical methods can be used as the prediction method, and for example, the rate of change ΔP, Δ in the position P and the velocity V can be used.
A method of predicting that V is constant, a method of using a Lagrange's interpolation polynomial, or a method of Newton's interpolation polynomial can be used, and this method will be described later. This prediction calculation is performed by the prediction calculation means 84A and 86A (FIG. 1).

By these means 84A and 86A, time t
The predicted values P _{i + 1} and V _{i + 1} of the stroke position / velocity obtained at _i at time t _{i + 1} are input to the duty ratio calculation means 90. The duty calculation means 90 stores in advance the duty ratio of the exciting current of the linear solenoid 44 that generates the optimum damping force with respect to the stroke position P, the speed V, and the expansion / contraction direction in the form of a map. CPU
Reference numeral 82 reads the signal d indicating the corresponding duty ratio from this map based on the position P, the speed V, and the direction.

The pulse width control means (PWM) 92 outputs a pulse width control signal D based on the signal d of this duty ratio. When this signal D is output from the CPU 82, the integrating circuit 94 outputs a current command signal i whose voltage changes according to the duty ratio. The current control circuit 96 outputs the exciting current I of the linear solenoid 44 based on this signal i.

Next, a method of predicting the stroke position P and the speed V will be described. FIG. 4 is an explanatory diagram of a method of predicting using the change rates ΔP and ΔV, and FIG. 5 is an operation flow chart in that case.

The actual position p _i-1 before prediction and the velocity v _i-1 at the present time t _{i- 1} are obtained and stored (step 100 in FIG. 5). In FIG. 4, only the position p is shown and the speed v is omitted for simplification. Δt is the time required for the attenuator to detect the position p ₀ and generate the corresponding damping force, that is, the operation delay time. Next, time t after Δt
position p ⁱ of _i, determine the velocity v _i (Step 10
2) The rate of change Δp _i , Δv _i during this time Δt is calculated by the following equation (step 104). Δp _i = (p _i −p _i−1 ) / Δt Δv _i = (v _i −v _i−1 ) / Δt

Next, using the change rates Δp _i and Δv _i , Δ
The position p _{i + 1} and the velocity v _{i + 1} at t _{i + 1} after t are predicted (step 106). p _{i + 1} = p _i + Δp _i · Δt v _{i + 1} = v _i + Δv _i · Δt The predicted new positions P _i and V _i are input to the duty ratio calculation means 90, and linearized as described above. The exciting current I of the solenoid is obtained (step 108).
According to this method, for the error when no prediction is made,
It can be seen from FIG. 4 that the error is very small.

The method using the Lagrange's interpolation polynomial is described in many documents relating to interpolation, and therefore detailed description thereof will be omitted. For example, when a fifth-order polynomial is used, the values of the past four points and the present point are The differential value of the present point can be obtained using to predict the value of the future point.

For example, the delay Δt of the control system is set to 20 msec,
Further, since the section average of 40 msec is obtained when measuring the relative position so as not to respond to vibration of a frequency higher than the unsprung resonance point, a delay of 20 msec is further generated. Relative displacement is measured at 2 mec intervals and stored in memory to create a data string for 5 consecutive points, that is, 100 msec. This data string is updated sequentially.

[0026] t _i 20msec before and after the time of the relative displacement t _i at the time of
The data (21 pieces) of is obtained by averaging and is set as U _i .
Similarly to t _i-1 ~t _i-4 the average of data for each _{U i-1, U i-} 2, U i-3, U i-4. U ′ _i = 1 / (12 · Δt) {3U _i-1 −16U _i-3 +
36U _i-2 −48U _i-1 + 25U _i } U ″ _i = 1 / (12Δt ² ) {11U _i-4 −56U _{i-3 according to the} second derivative calculation formula.
+ 114U _i-2 −104U _i-1 + 35U _i } Δt after the relative displacement U _{i + 1} is U _{i + 1} = U _i + U ′ _i × Δt Similarly, the relative velocity U ′ _{i + 1} is U ′ _{i + 1} = Each can be predicted by U ′ _i + U ″ _i × Δt.

It should be noted relative displacement U _i at t _i in this example t
_i time 20msec delay sought from, because delay 20msec of the control system is applied to it, the control performed on the basis of the relative displacement until t _i will be executed as it delayed 40msec from the time t _i. Therefore, the delay of the control system can be compensated for by the averaging process by predicting and controlling the state 40 msec ahead from the time t _i based on the relative displacement up to the time t _i . Further, in each of the above embodiments, the damping force is obtained using both the stroke position and the velocity, but the present invention may obtain the damping force based on either the position or the velocity.

[0028]

As described above, the present invention predicts the stroke signal indicating at least one of the stroke position and the speed of the piston in consideration of the operation delay of the attenuator, and the predicted stroke position and speed. Since the damping force is generated by using, it becomes possible to generate the damping force corresponding to the road surface condition during traveling.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an embodiment in which the present invention is applied to a motorcycle.

FIG. 2 is a sectional view showing a cushion unit for rear wheel suspension.

FIG. 3 is an explanatory diagram of the principle of the stroke sensor.

FIG. 4 is an explanatory diagram of an example of a prediction method.

FIG. 5 is an operation explanatory diagram of this prediction method.

[Explanation of symbols]

30 pistons 84A, 86A prediction calculation means Δt delay time Stroke position as p stroke signal v Stroke speed as a stroke signal

[Procedure amendment]

[Submission date] October 22, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

The attenuator 24 includes a cylinder 28 that is axially supported on the rear arm 18, a piston 30 that slides in the cylinder 28, and a piston rod 32 that is connected to the piston 30 and extends upward. An upper bracket 34 is fixed to the upper end of the piston rod 32, and is pivotally supported on the seat rail side. 36, 38
Is a cap attached to the upper opening of the cylinder 28, and the piston rod 32 penetrates the caps 36 and 38.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

In this embodiment, the piston rod 32 is made of a non-magnetic material such as aluminum, stainless steel, copper , brass, ceramics or the like in a pipe shape, and the magnetic rod 50 is inserted and accommodated therein. On the other hand, the annular permanent magnet 56
Was attached to the cap 38. The magnetic rod 50 is attached to the upper bracket 34 at the upper end of the piston rod 32.
Holds a pickup 60 connected to the upper end of the.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

In the present invention, the stroke position p
Based on the stroke speed v and the stroke speed v, the position P and the speed V after a predetermined time Δt has elapsed are calculated and predicted. This time Δt is at least a time corresponding to the operation delay of this attenuator. For example, the speed V at a plurality of time points before a predetermined time
Of the velocity V after the lapse of Δt from the change of
After obtaining the estimated speed V and the current position P, Δt elapses
The position P of is calculated by the prediction calculation means 84A. Various mathematical methods can be used for this prediction,
For example, a method of predicting the rate of change ΔP and ΔV of the position P and the speed V as constant, a method of using a Lagrange's interpolation polynomial or a Newton's interpolation polynomial, and the like can be used, and this method will be described later. This prediction calculation is performed by the prediction calculation means 84A and 86A (FIG. 1).

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

The actual position p _i-1 before prediction and the velocity v _i-1 at time t _{i- 1} are obtained and stored (step 100 in FIG. 5). In FIG. 4, only the position p is shown and the speed v is omitted for simplification. Δt is the position p of this attenuator
_This is the time required from the detection of _O to the generation of the corresponding damping force, that is, the operation delay time. Next, the position p _i and the velocity v _i at time t _i after Δt are calculated (step 1
02), the rate of change Δp _i , Δv _i during this time Δt
Is calculated by the following equation (step 104). _{Δp i = p i -p i-} 1 Δv i = Ap i / Δt

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0023

[Correction method] Change

[Correction content]

Next, this change rate Δp_i, Δv_iUsing
t after t_{i + 1}Position p at_{i + 1}, Speed v_{i + 1}To
Predict (step 106).       v _{i + 1} = Δv _i + (Δv _i −Δv _i−1 ) = 2 · Δvi _i−1 Δv _i−1       p _{i + 1} = p _i + Δv _{i + 1} × Δt New position P that predicted this_i, V_iAs duty
Input to the ratio calculation means 90, and the linear
The exciting current I of the solenoid is obtained (step 108).
According to this method, for the error when no prediction is made,
It can be seen from FIG. 4 that the error is very small.

[Procedure correction 6]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

For example, the delay of the control system is set to 20 msec,
Further, since the section average of 40 msec is obtained when measuring the relative position so as not to respond to vibration of a frequency higher than the unsprung resonance point, a delay of 20 msec is further generated. Relative displacement is measured at 2 mec intervals and stored in memory to create a data string for five consecutive points, that is, 200 msec. This data string is updated sequentially.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

[0026] t the relative displacement of the time _{i t i} at the time of before and after 20m
The data (21 data) of sec is averaged to obtain U _i . Similarly, time points t _{i-1 to} t at 40 msec intervals
The average of the data for _i-4 is U _i-1 , U, respectively.
_i-2 , U _i-3 , and U _i-4 . U ′ _i = 1 / (12 · Δt) {3 U _i −4−16U
_i-3 + 36U _i- 2-48U _i-1 + 25U _i } U ″ _i = 1 / (12Δt ² ) {11U _i- 4-56U according to the operation formula of the second derivative.
_i-3 + 114U _i-2 -104U _i-1 + 35U _i } Relative displacement after Δt time U _{i + 1} is U _{i + 1} = U _i + U ′ _i × Δt Similarly, relative velocity U ′ _{i + 1} is U ′ _{i + 1} = U ′ _i + U ″. Each can be predicted by _i × Δt.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

It should be noted relative displacement _{U i} at _{t i} in this example t
_The delay is obtained 20 msec after _i o'clock, and the control system delay of 20 msec is added. Therefore, the control based on the relative displacement until t _i o is executed at a time 40 msec later than t _i o. Therefore, the delay of the averaging process and the control system can be compensated by predicting and controlling the state 40 msec ahead from the time t _i based on the relative displacement up to the time t _i . Further, in each of the above embodiments, the damping force is obtained using both the stroke position and the velocity, but the present invention may obtain the damping force based on either the position or the velocity.

[Procedure Amendment 9]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Claims (2)

[Claims] 1. A control signal for generating an optimum damping force is obtained based on a stroke signal including at least one of a stroke position and a stroke speed of a piston, and the control signal is detected by an attenuator which controls the damping force by the control signal. An attenuator, comprising: a prediction calculation unit that predicts the stroke signal at least ahead of the control delay time of the attenuator by using the stroke signal described above, and controls the damping force using the predicted stroke signal. . 2. The attenuator according to claim 1, wherein the prediction calculation means predicts the stroke signal using a Lagrangian interpolation polynomial.