JP3117014B2 - shock absorber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a shock absorber having a variable damping force.

(Prior Art) As a conventional shock absorber with a variable damping force, for example, a shock absorber used in a suspension described in Japanese Utility Model Laid-Open Publication No. 63-112914 is known.

This conventional suspension detects a relative displacement between sprung and unsprung, and if the displacement is a change in a direction away from the neutral position, sets the damping force to a low damping force (soft) and returns to the neutral position. In the case where the change in the direction of the shock absorber is a high damping force (hard) and the relative displacement between the sprung and unsprung conditions requires switching between hard and soft in a shorter time than the switching time of the shock absorber. , The software state is forcibly set to the soft state.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional vehicle suspension, when the hardware is used, both the extension side and the compression side are hardware, and therefore, there is a problem described below.

When the damping force is hard at the time of low frequency vibration, and at the same time the input of medium and high frequency vibration components due to fine irregularities on the surface of the road surface etc., the low frequency vibration is prioritized as hard In this case, both the extension side component and the compression side component of the high frequency vibration component are input to the vehicle body to deteriorate the ride comfort.

If the response to the middle and high frequency components is prioritized and the software is forcibly made soft, the vibration input to the vehicle body is suppressed, but the steering stability is deteriorated.

 That is, it was not possible to achieve both steering stability and ride comfort.

The present invention has been made by paying attention to the conventional problems as described above, and can achieve both steering stability and ride comfort in a state where low-frequency vibration and medium / high-frequency vibration are simultaneously input. It is intended to provide a shock absorber.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a two-liquid chamber in a cylinder defined by a piston sliding in a cylinder in which a working fluid is sealed. Two passages, an extension side passage and a pressure side passage, which communicate the two fluid chambers with each other, are formed independently, and the flow of the hydraulic fluid from one fluid chamber to the other fluid chamber during the extension stroke is formed in the extension side passage. A hydraulic disc valve is provided which allows only the flow of hydraulic fluid from the other fluid chamber to the one fluid chamber during the compression stroke. In the shock absorber, an adjuster traversing the extension-side passage and the compression-side passage is rotatably disposed, and a communication hole that penetrates the adjuster in a diametrical direction is provided. The state of the low pressure passage located in each passage and the position A high-pressure passage state that is not placed can be formed, and two sets of communication holes having the same diameter are formed in the extension-side passage and the compression-side passage, respectively, and one of the two communication holes in the extension-side passage is formed. When only the communication hole is in the low-pressure passage state, the communication hole of the compression-side passage is formed in the high-pressure passage state, and the S / H position in which the expansion side formed with low damping force and the compression side has high damping force, and two sets of expansion-side passages. When another set of the communication holes is in the low-pressure passage state, the pressure-side passage 2
One of the communication holes is formed in a low-pressure passage state, and the S / S position has a low damping force on both the extension side and the compression side. The other one of the communication holes is in a low pressure passage state, and the H / S position of the extension side formed with high damping force and the compression side with low damping force can be sequentially formed. It is characterized in that the position of the communication hole of the passage is offset by 60 degrees.

(Operation) An operation when the shock absorber of the present invention is applied to a vehicle suspension that changes the position in accordance with the sign of the sprung vertical speed and the sign of the sprung-unsprung relative speed will be described.

The control signal output means includes a sprung speed measured by a sprung speed measuring means, a relative speed between sprung and unsprung measured by a relative speed measuring means, The result of the determination as to whether the sign of the speed and the sign of the relative speed match or not is input.

When the sprung speed and the sign of the relative speed match and the relative speed is positive, it is determined that the damping force of the shock absorber is acting in the vibration damping direction and that the stroke is the extension stroke. , High damping force on the extension side and low damping force on the compression side
H / S position.

Further, when the sign of the sprung speed and the relative speed match, and the relative speed is negative, it is determined that the damping force of the shock absorber acts in the vibration damping direction, and that the stroke is the compression side stroke, Low damping force on the extension side and high damping force on the compression side
S / H position.

In this way, when the sign of the sprung speed and the relative speed match, the damping force of the shock absorber acts in the vibration damping direction. In this case, the damping force in the stroke direction is set to a high damping force. By increasing the damping energy with respect to the vibration energy transmitted to the vehicle body, the steering stability can be improved, and the damping force in the direction opposite to the stroke is reduced to a low damping force, so that the vibration is transmitted to the vehicle body. Inside the reverse stroke side
It is capable of absorbing the input of high-frequency components and improving ride comfort.

On the other hand, when the sign of the sprung speed and the sign of the relative speed do not match, the damping force of the shock absorber acts in the exciting direction, so that the S / S position has a low damping force on both the extension side and the compression side.

Therefore, the ride energy is improved by absorbing the vibration energy transmitted to the vehicle body.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

 First, the configuration of the embodiment will be described.

FIG. 2 is a schematic view showing the configuration of a suspension to which the shock absorber of the embodiment of the present invention is applied. As shown in FIG. 2, the suspension A is interposed between a vehicle body B and each wheel W. Strut 10 and this strut
Load sensor 11 and acceleration sensor 12 provided at the base end of 10
And a controller 13 that outputs a control signal s based on input signals d and a from the sensors 11 and 12.

FIG. 2 shows one wheel W and a set of struts 10 and both sensors 11 and 12 corresponding thereto. The set of struts 10 and both sensors 11 and 12 are
It is provided for each wheel W.

 Reference numeral 14 in FIG. 2 denotes a mount insulator.

The strut 10 has a shock absorber 20 of a variable damping force type and a spring 30. The structure of the shock absorber 20 will be briefly described with reference to a cross-sectional view of a main part in FIG.

In the figure, reference numeral 21 denotes a cylindrical cylinder.
The cylinder 21 is filled with a fluid such as oil, and has an upper chamber 23 and a lower chamber 24 defined by a slidably loaded piston 22.

The piston 22 is attached to the tip of a piston rod 25.A compression-side disc 22a is provided on the upper surface of the piston 22, and an extension-side disc valve 22b is provided on the lower surface.
Is provided.

That is, during the compression side stroke, the fluid for opening the compression side disk valve 22a flows from the compression side communication hole 22h in the inner and outer grooves 22j and 22k, and a damping force is generated. Also, at the time of the extension stroke, the fluid for opening the extension-side disc valve 22b is similarly circulated in the inner and outer grooves 22n and 22p from the extension-side communication hole 22m, and a damping force is generated.

22c is a retainer, 22d and 22e are washers, 22f is a spring seat, and 22g is a spring.

The piston 22 and the piston rod 25 have grooves.
A pressure-side flow path 22q connecting the groove 22j and the groove 22k is formed (see FIG. 4), and an expansion-side flow path 22r connecting the groove 22n and the groove 22p is formed. A child 26 is provided.

The adjuster 26 is provided so as to be rotatable in the circumferential direction, and is formed in a cylindrical shape with a bottom having a hollow portion 26a as shown in the figure. A hole 26b is formed, and a growth-side communication hole 26c is formed corresponding to the growth-side flow path 22r.

As shown in FIG. 5 which is a VV cross section of the adjuster 26 and the piston rod 25 and FIG.
The compression-side communication holes 26b have α,
Of the three axes β and γ, the three-axis is formed on two axes of the α-axis and the β-axis, while the extension-side communication hole 22c is formed on two axes of the α-axis and the γ-axis.

That is, the compression-side flow path 22q and the extension-side flow path 22r are
Due to 26b and the extension side communication hole 26c, a low damping force (hereinafter referred to as soft) is obtained when the communication is established, and a high damping force (hereinafter referred to as "hard") when the flow paths 22q and 22r are cut off by the adjuster 26. Becomes

Therefore, when the α axis of the adjuster 26 is matched with both the flow paths 22q and 22r, both the extension side and the compression side are in the soft S / S position, and when the β axis is matched. , The H / S position of the expansion side hardware and compression side software, and when the γ axis is matched, the expansion side software and compression side hardware S / H
Position.

The rotation of the adjuster 26 is controlled by the through hole 25 of the piston rod 25.
a is formed by a control rod 27 provided in a.
The piston rod 25 extends to the upper end thereof, and is provided with a rotational force by an actuator 28 provided on the body mounting portion of the piston rod 25 (see FIG. 2).

The load sensor 11 is fastened together with the mounting portion of the piston rod 25 to the vehicle body B, and can output an electric signal d corresponding to the load input to the mounting portion of the piston rod 25 by a structure having a strain resistance. ing.

That is, the load sensor 11 is provided as relative speed measuring means for measuring the relative speed between sprung and unsprung, and a predetermined load obtained when the shock absorber 20 is in the neutral position is set as a reference value and detected. The relative speed can be determined based on whether the load is higher or lower than the reference value. That is, in the case of the present embodiment, on the extension side where the relative speed is positive, the detected load is equal to or higher than the reference value. In the negative pressure side stroke, the mounting structure is such that the detected load is less than the reference value.

The acceleration sensor 12 is provided in the actuator 28, and outputs an electric signal a corresponding to the vertical acceleration acting on the upper end of the piston rod 25 which is sprung. That is, the acceleration detected by the acceleration sensor 12 is a differential value of the sprung speed, and the acceleration sensor 12 is provided as sprung speed measuring means. In the acceleration sensor 12, the upward acceleration is obtained as a “positive” value, and the downward acceleration is obtained as a “negative” value.

The controller 14 outputs a control signal s to the actuator 28 based on the input signals d and a from the load sensor 11 and the acceleration sensor 12 in order to make the shock absorber 20 have the optimum damping force. Shows the structure.

That is, the controller 13 outputs signals d and a from both the sensors 11 and 12.
An input / output interface circuit 13a, an A / D conversion circuit 13b for converting an input analog signal into a digital signal, a CPU 13d for performing calculations and determinations to be described later based on input signals and numerical values stored in a memory circuit 13c, and the CPU 13d Calculation of
Drive circuits 13e and 13f for outputting a control signal s to the actuator 28 based on the determination result are provided.

Next, the operation of the controller 13 will be described with reference to the flowchart shown in FIG.

First, in step 101, initialization is performed to set the signs of the detected load D and the detected acceleration A to “positive”.

Next, in steps 102 and 103, the A / D conversion circuit 13b performs A / D conversion of the input signal d indicating the load D and the input signal a indicating the acceleration A.

Next, in step 104, it is determined whether or not the acceleration A on the spring is a local maximum. That is, the determination step 104 and the next determination step 105 are to determine the state of the sprung speed based on the sprung acceleration A, and from the time when the acceleration A becomes the maximum to the time when the acceleration A becomes the next minimum, It is determined that the sprung speed is “positive”, and a process of setting the sign of the acceleration A to “positive” is performed in the processing step 106.
During the period from when the minimum value to the next maximum value is reached, it is determined that the sprung speed is “negative”, and a process of setting the sign of the acceleration A to “negative” in processing step 107 is performed.

Next, in step 108, it is determined whether or not the load D is equal to or larger than the reference value. That is, as described above, this load D
Is input in order to measure the relative speed. If the load D is equal to or more than the reference value, it is in a state where the extension side stroke in which the relative speed becomes positive is performed. Is "positive".

On the other hand, when the load D is less than the reference value, it means that the pressure side stroke in which the relative speed becomes negative is performed, and the sign of the load is set to “negative” in step 110.

Next, in step 111, a calculation for multiplying the acceleration A and the load D is performed as a previous step for determining whether the signs of the acceleration A and the load D match. That is, if the two codes match, the multiplied value C is “positive”, and if they do not match, the value C is “negative”.

Then, in the subsequent determination step 112, it is determined whether or not the calculated value C is positive. If the result is “positive” (YES), the process proceeds to the next determination step 113, where the load is “positive”.
It is determined whether it is “positive” (YES). If the answer is “YES”, the routine proceeds to step 114, where the motor actuator 28 is set so that the damping force characteristic of the shock absorber 20 is set to the H / S position of the hard side and the compression side to the soft H / S position. To output a control signal s.

That is, the β axis of the adjuster 26 shown in FIGS. 5 and 6 is matched with the compression-side flow path 22q and the expansion-side flow path 22r, and the compression-side flow path 22q is made to flow, while the expansion-side flow path 22r is shut off. The adjuster 26 is rotated in such a state as to perform the adjustment.

If the load is not “positive” (NO), step 115
Then, the control signal s is output to the motor actuator 28 so that the damping force characteristic of the shock absorber 20 is set to the S / H position where the compression side is hard and the expansion side is software.

That is, the γ-axis (FIGS. 5 and 6) of the adjuster 26 is matched with the compression-side flow path 22q and the expansion-side flow path 22r to shut off the compression-side flow path 22q and connect the expansion-side flow path 22r to the expansion-side communication. The adjuster 26 is rotated so as to communicate with the hole 26c.

On the other hand, if NO is determined in step 112, the process proceeds to step 116, where both the compression side and the extension side are soft S / S
The control signal s is output to set the position. That is, the α-axis (the fifth and sixth axes) of the adjuster 26 with respect to the compression-side flow path 22q and the extension-side flow path 22r.
The regulator 26 is rotated so that both the pressure side flow path 22q and the expansion side flow path 22r are in communication with each other.

Next, the operation of the embodiment in each traveling situation of the vehicle will be described.

(A) Rolling For example, at the time of turning right, the vehicle body B rolls, the right side of the vehicle body is displaced upward, the left side of the vehicle body is displaced downward, and then converges to the neutral position while vibrating.

FIG. 9 is a time chart showing the sprung displacement of the vehicle body left and right, the state of the sign of the acceleration A and the load D detected on the vehicle body left and right, and the damping force characteristics of the shock absorber 20 on the vehicle body left and right during a right turn. It is a chart.

The aRH displacement and the bLH displacement in FIG. 9 indicate the displacement states of the right and left sides of the vehicle body, respectively. The solid line indicates the sprung displacement, and the dotted line indicates the sprung speed. In this case, the road surface is flat.

The cRH acceleration A and the load D thereunder are given by the processing steps 106, 107, 109 and 110 in FIG. 8 based on the input signals from the acceleration sensor 12 and the load sensor 11 on the right side of the vehicle body corresponding to the displacements shown in a and b. The signs of the acceleration A and the load D are shown.

The dLH acceleration A and the load D indicate the same sign of the acceleration A and the load D on the left side of the vehicle body.
Note that the first range of c and d indicates a code corresponding to the initial setting in step 101.

Further, the e-damping force thereunder indicates the damping force characteristic of the shock absorber 20 determined as a result of the calculation and determination of the controller 13 shown in the flowchart of FIG. LH indicates a damping force characteristic (H: hard, S: soft), and LH indicates a damping force characteristic of the shock absorber 20 on the left side of the vehicle body.

Therefore, during such a roll, the shock absorber 20 always repeats the extension stroke and the compression stroke in such a manner that the damping force always acts in the damping direction (the signs match).

Therefore, the shock absorber 20 can always suppress the roll with the stroke direction being hard, and obtain steering stability. Also, at this time, the reverse stroke side is controlled softly, and at the same time when there is a middle or high frequency input from the road surface during such vibration control, the vibration in the reverse stroke direction is absorbed and the riding comfort is improved. Can be done.

(B) Dive and scut At the time of braking and acceleration, dive and scut occur.

In this case as well, control is performed to suppress such a change in posture, as in the case of rolling.

Therefore, the operation in this case is an operation in which the control performed on the left and right during the roll is replaced as it is, that is, the expansion side is made hard and the compression side is made soft,
A state in which the extension side is damped is alternately controlled to a state in which the extension side is soft and the compression side is hard, and the compression side is damped, thereby suppressing scut and dive.

(C) At the time of bouncing FIG. 10 shows a time chart at the time of traveling on a rough road.

When traveling on such a rough road, each shock absorber 20 strokes according to the unevenness of the traveling road surface of each wheel. In FIG. A, the sprung displacement is indicated by a solid line, the sprung displacement, and the displacement speed is indicated by a dotted line. Is shown.

And the road surface displacement b below it indicates the state of the road surface R and the wheels W.

Further, in the relative displacement c below, the relative displacement is indicated by a solid line, and the relative speed is indicated by a dotted line.

In such a case, the sign of the acceleration A (corresponding to the sign of the sprung speed) and the load D (corresponding to the sign of the relative velocity) given by the calculation and determination in the controller 13
Are as shown in FIG.

As a result, the damping force characteristic of the shock absorber 20 controlled by the controller 13 becomes as indicated by e damping force.

FIG. 5F shows the stroke direction of the shock absorber 20.

In other words, in this time chart, in the range of (1), the extension side is hard,
The pressure side is soft (H / S position) (β-axis sign state).

In the range of (2), the sign of the acceleration A and the sign of the load D are different, that is, the damping force acts in the excitation direction, so that both the extension side and the compression side are soft (S / S position). ) Is performed to absorb the input and improve the ride comfort (α-axis matching state).

Next, in the range of (3), the stroke direction is switched to the extension side, and the damping force changes to the state of acting in the damping direction. Therefore, the extension side is hard and the compression side is soft (H / S position).
(Β-axis coincidence state), aiming to improve both steering stability and ride comfort.

Next, in the range of (4), since the damping force is acting in the excitation direction during the extension side stroke, the extension side and the compression side are softened (S / S position) (α axis coincidence state). ), To improve ride comfort.

Next, in the range of (5), the stroke direction is switched to the compression side, and the damping force changes to a state acting in the vibration damping direction. Therefore, the extension side is soft, and the compression side is hard (S / H position).
(Gamma-axis matching state) to achieve both steering stability and ride comfort.

Next, in the range of (6), the compression side stroke is being performed, and the damping force changes to a state in which it acts in the vibration direction.
Both sides of the compression side are made soft (S / S position) (α-axis sign state) to improve ride comfort.

Next, in the range of (7), the stroke direction is switched to the extension side, and the damping force changes to the state of acting in the damping direction, so the extension side is hard and the compression side is soft (H / S position).
(In the state of coincidence with the β-axis), aiming to achieve both steering stability and ride comfort.

As described above, in accordance with the input from the road surface R and the movement on the sprung, the damping force of the shock absorber 20 is controlled in a direction to minimize the rate of change of the energy on the sprung, and the bouncing is damped.

Although the embodiment of the present invention has been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and even if there is a design change or the like without departing from the gist of the present invention, the present invention is not limited thereto. included.

For example, in the embodiment, means for measuring acceleration is provided as means for measuring sprung speed, but other means may be used as long as it can measure sprung speed.

In the embodiment, as means for measuring the relative speed,
Although the load sensor is used, other means such as a means for measuring a sprung-unsprung relative displacement may be used.

(Effects of the Invention) As described above, in the shock absorber of the present invention, when damping force with a high damping force on the stroke direction side,
Since the reverse stroke direction has a low damping force, it is possible to prevent transmission of input of the medium and high frequency components that are input during this vibration suppression on the opposite side to the stroke direction, thereby improving steering stability and ride comfort. The effect that both can be achieved is obtained.

[Brief description of the drawings]

1 is a block diagram showing a basic configuration of the present invention, FIG. 2 is an overall view showing a suspension A of an embodiment of the present invention, FIG. 3 is a cross-sectional view showing a main part of a shock absorber of the suspension of the embodiment, FIG. 4 is a sectional view showing an upper end portion of a piston which is a main part of the embodiment, FIG. 5 is a sectional view taken along line VV of FIG. 3, FIG. 6 is a sectional view taken along line VI-VI of FIG. FIG. 13 is a block diagram showing a controller of the suspension according to the eighth embodiment.
FIG. 9 is a flowchart showing the operation flow of the controller of the embodiment, FIG. 9 is a time chart showing the operation of the embodiment suspension during a right turn, and FIG. 10 is a time chart showing the operation of the embodiment suspension during the bouncing. . DESCRIPTION OF SYMBOLS 1 ... Shock absorber 2 ... Spring speed measuring means 3 ... Relative speed measuring means 4 ... Sign judgment means 5 ... Control signal output means A ... Suspension 11 ... Load sensor (relative speed measuring means) 12 ... ... acceleration sensor (spring speed measurement means) 13 ... controller (sign determination means, control signal output means) 20 ... shock absorber s ... control signal

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Mitsuo Sasaki 1370 Onna, Atsugi-shi, Kanagawa Prefecture Inside Atsugi Automotive Parts Co., Ltd. (72) Inventor Hiroyuki Shimizu 1370 Onna, Atsugi-shi, Kanagawa Prefecture Atsugi Automotive Parts Co., Ltd. (72) Inventor Junichi Emura 1370 Onna, Atsugi City, Kanagawa Prefecture Inside Atsugi Automotive Parts Co., Ltd. (56) References JP-A-61-163011 (JP, A) JP-A-62-253506 (JP, A) JP-A-63-173709 (JP, A) JP-A-60-199710 (JP, A) JP-A-62-198513 (JP, A) Japanese Utility Model Showa 62-70008 (JP, U) (58) (Int.Cl. ⁷ , DB name) B60G 17/015

Claims (1)

(57) [Claims] 1. A two-liquid chamber is defined in a cylinder by a piston that slides in a cylinder in which hydraulic fluid is sealed, and two passages of an extension-side passage and a pressure-side passage connecting the two liquid chambers to each other are independent. The expansion-side passage is provided with an expansion-side disk valve that allows only the flow of hydraulic fluid from one liquid chamber to the other liquid chamber during the expansion-side stroke, and the compression-side passage includes a compression-side In a shock absorber provided with a pressure-side disc valve that allows only the flow of the hydraulic fluid from the other liquid chamber to one of the liquid chambers during a stroke, a regulator that traverses the expansion-side passage and the pressure-side passage is rotatably arranged. A communication hole that penetrates the adjuster in the diameter direction is provided, and a low-pressure passage state in which the communication hole is located in each passage and a high-pressure passage state in which the communication hole is not located can be formed according to the rotational position of the adjuster. With, before When two sets of communication holes having the same diameter are formed in the extension side passage and the compression side passage, respectively, and only one of the two communication holes of the extension side passage is in the low pressure passage state, The communication hole of the passage is in a high-pressure passage state, and the S / H position in which the extension side formed with a low damping force and the compression side has a high damping force, and another of the two communication holes in the extension side passage are in a low-pressure passage state. When one of the two communication holes of the compression-side passage is in the low-pressure passage state, the S / S position of the low damping force is formed on both the extension side and the compression side, and the communication hole of the extension-side passage is in the high-pressure passage state. In addition, the other one of the two communication holes of the compression-side passage is formed into a low-pressure passage state, and the H / S position in which the expansion side formed with high damping force and the compression side with low damping force can be sequentially formed. A shock absorber characterized in that the positions of the communication holes between the extension side passage and the compression side passage are offset by 60 degrees. Soba.