JPH06221366A - Shock absorber - Google Patents

Abstract

PURPOSE:To provide a shock absorber which can be adjusted according to damping force to generate the damping coefficient of the shock absorber without adopting an expensive electronic control method. CONSTITUTION:As a damper element 11 whose damping coefficient is variable, and a spring element 13 are connected to each other in series, the resistance force of the damper element 11, that is, the damping force, and the extension/ contraction quantity of the spring element 13 are proportional to each other, and the spring element 13 detects the damping force of the damper element 11. A control mechanism 2, on the basis of control force according to the detected extension/contraction quantity (the damping coefficient of the damper element 11) of the spring element 13, conducts the feedback control of the damping force of the damper element 11. As a result, the damping coefficient of the damper element 11 is decided at a proper characteristic by means of the control mechanism 2.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a shock absorber.

[0002]

2. Description of the Related Art Conventionally, for example, a shock absorber used for a suspension of an automobile has a constant damping coefficient C and a relative speed (dx ₂ / dt) between a vehicle body and a tire as shown in FIG. -Dx ₁ / dt), that is, a damping force, that is, a resistance Fd of the shock absorber is generated. Therefore, if the damping coefficient is increased in order to quickly damp the vibration dx ₂ / dt of the heavy vehicle body, the tire vibration dx ₁ due to the unevenness of the road surface
The force due to / dt also increases, which is transmitted to the vehicle body, resulting in a very bad ride. Conversely, if the damping coefficient is reduced in order to improve the riding comfort, the vehicle body vibration dx ₂
There is a problem that / dt is not easily attenuated and a sufficient vibration damping effect cannot be obtained.

Damping force: Fd = −C (dx ₂ / dt−dx ₁ / dt) Formula a In order to solve this problem, Japanese Patent Laid-Open No. 59-97337 discloses a spring-mass system in a shock absorber. We proposed to improve the riding comfort by incorporating a vibrating body and opening and closing the flow path according to this vibration characteristic to reduce the damping coefficient value outside the resonance frequency band of the vehicle body and tires. ing.

Further, JP-A-64-67407 discloses
Using an electronically controlled damping force variable shock absorber,
When the change rate signal of the damping force becomes larger than the set value, the switching control is performed so that the damping coefficient is reduced for a certain period of time. Thus, the damping force of the vehicle body vibration dx ₂ / dt is sufficiently secured, and the tire vibration dx due to the unevenness of the road surface.
It proposes to reduce the force due to ₁ / dt and improve the riding comfort.

[0005]

However, in the method disclosed in Japanese Patent Laid-Open No. 59-97337, the resonance of the spring-mass system is used to open the passage, so that when traveling on a road surface of a single frequency. Although there is a certain effect, when traveling on an actual road surface with various frequencies combined, there is a time delay until reaching resonance, so in reality it was not possible to achieve a sufficient improvement in riding comfort.

On the other hand, since the method disclosed in Japanese Patent Laid-Open No. 64-67407 is an electronic control method, an electronic control unit, a damping force sensor for each wheel, and an actuator capable of high-speed response are used.
However, the complexity of the configuration was brought about, and there was a problem in economical efficiency and reliability. The present invention has been made in view of the above problems, without employing an expensive electronic control system,
It is an object of the present invention to provide a shock absorber that can be adjusted according to the damping force that generates the damping coefficient of the shock absorber.

[0007]

In order to achieve the above object, a shock absorber according to the present invention comprises a spring element and a damper element having a variable damping coefficient, which are connected in series, and the damper according to the expansion / contraction amount of the spring element. And a control mechanism for changing the damping coefficient of the element. In a preferred aspect, the spring element, the damper element and the control mechanism are internally provided in the same casing.

In a preferred aspect, the control mechanism sets the damping coefficient for a low frequency component, which corresponds to the resonance frequency component of the mass, and the damping coefficient for other frequency components, among the changes in the expansion and contraction amount of the spring element. It is set relatively larger.

[0009]

[Function] Since the damper element having the variable damping coefficient and the spring element are connected in series, the resistance force of the damper element, that is, the damping force and the expansion / contraction amount of the spring element are proportional to each other, and the spring element detects the damping force of the damper element. Will be done. The control mechanism feedback-controls the damping coefficient of the damper element based on the detected expansion / contraction amount of the spring element, that is, the control force corresponding to the damping force of the damper element. This determines the damping force of the shock absorber of the present invention.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the shock absorber of the present invention will be described below with reference to the drawings. FIG. 1 shows a basic configuration when the shock absorber of the present invention is applied to an automobile suspension. As a matter of course, even if the spring element 13 and the damper element 11 are reversely arranged in FIG. 1, the operation is the same.

A mass 3 on the vehicle body side having a mass of M ₂ and a mass of M
_The tire side mass 4, which is ₁ , is connected by a spring element 13 and a damper element 11 which are connected in series to each other, and
It is connected by a spring element 5. K ₁ is the elastic coefficient of the tire, K ₂ is the elastic coefficient of the spring element 5, and K ₃
Is the elastic coefficient of the spring element 13. The control mechanism 2 causes the damper element 11 to exert a control force according to the expansion / contraction amount (X ₂ −X ₃ ) of the spring element 13 which is a change in the positions of both ends of the spring element 13, and the damper element 11 according to the control force. Damping coefficient C
Change.

An example of the control mechanism 2 of FIG. 1 will be described with reference to the control procedure diagram block diagram of FIG. In this example, according to the low frequency component (mainly the vibration of the vehicle body side mass 3) of the expansion / contraction amount of the spring element 13 (the vibration of the mass 3 and the mass 4),
The damping coefficient C of 1 is increased. First, the spring element 1 proportional to the damping force (resistance of the damper element 11) Fd
The expansion / contraction amount e = (x ₂ −x ₃ ) of ₃ is enlarged by the proportional constant α in the mechanism 201 and converted into the stroke m required for the control mechanism 2. Secondly, the stroke m is passed through the primary low-pass filter mechanism 202 to extract a low frequency component (usually 1 to 2 [Hz]) near the resonance frequency of the vehicle body as a stroke l. Thirdly, the mechanism 203 increases the value of the damping coefficient C of the damper element 11 in proportion to the magnitude of the stroke 1 representing the resonance of the vehicle body. In the mechanism 203, first 20
At 4, the stroke 1 is converted into an absolute value. Next, at 205, the value of the flow path resistance (attenuation coefficient) Cv of the sub flow path provided in the damper element 11 is increased in proportion to the absolute value 1. Finally, at 206, the flow path resistance (damping coefficient) C ₀ of the damper element 11 as a whole is combined with the flow path resistance (damping coefficient) C _{0 of} the main flow path also provided in the damper element 11. .

Next, another example of the control mechanism 2 of FIG. 1 will be described with reference to the control procedure diagram block diagram of FIG. In this example, the expansion / contraction amount of the spring element 13 (vibration of the mass 3 and the mass 4)
In accordance with the high frequency component (mainly the vibration of the tire side mass 4)
The damping coefficient C of the damper element 11 is reduced.
First, similarly to FIG. 2, the spring element 13 proportional to the damping force Fd is used.
The expansion / contraction e = (x ₂ −x ₃ ) is expanded by the mechanism 211 by the proportional constant α and converted into the required stroke m. Second,
The stroke m is passed through the primary high-pass filter mechanism 212, and a high frequency component (normally 4 [Hz] or more) that deteriorates the riding comfort due to the unevenness of the road surface is extracted as the stroke h. Thirdly, the mechanism 213 reduces the value of the damping coefficient C of the damper element 11 in proportion to the size of h representing the protrusion on the road surface. The mechanism 213 first converts the stroke h into an absolute value at 214. Next, at 215, the value of the flow path resistance (attenuation coefficient) Cv of the sub flow path provided in the damper element 11 is decreased in proportion to the absolute value h. Finally, at 216, this is combined with the flow path resistance (damping coefficient) C _{0 of} the main flow path also provided in the damper element 11 to obtain the flow path resistance (damping coefficient) C of the damper element 11 as a whole. .

Next, the operation of the apparatus shown in FIGS.
explain. 1, the displacement of the road surface is r, the tire and the vehicle
Vertical displacement of the body x₁, X ₂, Damper element 11 and
X is the vertical displacement of the connecting portion of the spring element 13.₃far. Do
And the damping force Fd of the shock absorber 1 as a whole is
It can be expressed by the following equation b. Fd = -C (dx₃/ Dt-dx₁/ Dt) =-K₃(X₂-X₃) Expression b Here, the spring constant K of the spring element 13₃The value of is known
Therefore, from equation b, the damping force Fd of the shock absorber 1 is
Expansion amount e = (x of element 13₂-X₃)
Become. That is, whether the spring element 13 expands or contracts without a sensor.
And the damping force Fd of the shock absorber 1 is known.
It

Further, as shown in FIG. 1, the desired component is extracted from the expansion amount e of the spring element 13 proportional to the damping force Fd by an appropriate control mechanism 2, and the damper element 1 is extracted by this extracted component.
The damping coefficient C of 1 is changed. This allows
With respect to the damping coefficient C of the shock absorber 1, it is possible to give an arbitrary adjusting function according to the damping force Fd within a range that can be realized by the control mechanism 2.

As described above, according to the above embodiment,
It becomes possible to realize control mechanically or mechanically according to the damping force Fd itself generated by the shock absorber 1 without performing electronic control using an electronic control unit, a sensor, and an actuator. Note that, for example, when considering a shock absorber of an automobile, the damping force Fd
Of the (normally several 100N to several 1000N), the spring element 1
It is clear that even if the force (about several N to several tens N) for changing the damping coefficient C is taken out by the control mechanism 2 via 2, there is almost no effect on the whole.

Next, the control mechanism 2 of FIGS. 2 and 3 in which this is applied to an automobile suspension will be described. First, the mechanism of FIG. 2 will be described. As described above, it is possible to realize control to increase the value of the damping coefficient C only when the damping force Fd has a low-frequency component near the resonance frequency of the vehicle body. Therefore, when the vehicle body resonates, the value of the damping coefficient C increases and the vibration dx ₂ / dt of the vehicle body can be quickly damped. Further, when the vehicle body does not resonate, the value of the damping coefficient C remains small, and the force resulting from the tire vibration dx ₁ / dt due to the unevenness of the road surface can be reduced and the riding comfort can be improved.

Next, the mechanism of FIG. 3 will be explained. As described above, control for reducing the value of the damping constant C can be realized only when a high frequency component is generated in the damping force Fd due to the unevenness of the road surface. Therefore, normally, the vibration dx ₂ / dt of the vehicle body due to resonance can be quickly attenuated while the value of the damping coefficient C remains large, and when the vehicle passes through an uneven road surface, the value of the damping coefficient C becomes small, resulting in unevenness. It is possible to reduce the force caused by the tire vibration dx ₁ / dt due to the above and to improve the riding comfort.

As described above, in the present embodiment, it is possible to reliably and inexpensively provide the damping function of the shock absorber with the adjusting function suitable for the suspension of the automobile. Hereinafter, an example of an actual mechanism for realizing the shock absorber 1 described with reference to FIGS. 1 to 2 will be described with reference to FIGS. 4 to 7. The inner space of the cylinder 101 of the shock absorber 1 is divided into an upper space and a lower space by a main piston 111 that can slide in the cylinder 101.
a and 1b. A piston rod 220 is arranged along the axis of the cylinder 101, and the main piston 111 is mounted on the piston rod 220 by a screw 104.
Is fitted to the lower end of the. The upper end of the piston rod 220 is attached to the lower end of the shaft 103 extending upward through a spring 131 so as to be vertically slidable.

Further, the main piston 111 is fixed on the contraction side which vertically penetrates the outer peripheral portion thereof to communicate the hydraulic chambers 1a and 1b (closed when the main piston 111 rises).
A main flow passage 112 and a main flow passage 113 fixed to the extension side (closed when the main piston 111 descends) are formed.
The main flow passages 112 and 113 are provided on the upper surface and the lower surface of the main piston 111, respectively.
It is opened and closed by 14,115. Piston rod 22
In FIG. 0, the sub-flow passage 11 that runs from the side surface facing the upper hydraulic chamber 1a to the lower end of the piston rod 220 along the rod center
6 is formed, and the flow passage cross-sectional area of the sub-flow passage 116 is changed by the annular groove on the outer circumference of the valve (229 in FIG. 4, 231 in FIG. 6) that operates up and down.

The specific portion of FIG. 4 will be described below. An oil chamber is provided in the upper end of the piston rod 220, and a lower end 221 of the shaft 103 is formed in a piston shape. The lower end 221 of the shaft 103 is slidably fitted in the oil chamber. The oil chamber is divided into oil chambers 2a and 2b. The oil in the oil chamber 2a communicates with the oil chamber 1a through a hole 222 formed in the piston rod 220. Oil chamber 2
b is sealed by a piston rod 220, a lower end 221 of the shaft and a plunger 223.

On the other hand, a sliding hole 250, a shaft hole 251, and a sliding hole 252 are formed in this order from the top along the axis of the piston rod 220. The sliding hole 250 includes the oil chamber 2b and the shaft hole 25.
1 and the shaft hole 251 communicates with the sliding holes 250 and 252. The sliding hole 252 communicates with the sub flow path 116. The plunger 223 described above is slidably fitted in the sliding hole 250, and the lower end of the plunger 223 divides the shaft hole 251 into an upper oil chamber 2c and a lower oil chamber 2d. A spring 224 provided in the oil chamber 2c urges the plunger 223 downward, and a spring 225 provided in the oil chamber 2d urges the plunger 223 upward. The oil chamber 2c communicates with the hydraulic chamber 1a through a hole 226, and the oil chamber 2d communicates with the hydraulic chamber 1a through a hole 227.

A valve 229 is slidably fitted in the sliding hole 252, and the plunger 223 and the valve 229 are connected via a spring 228. Valve 2
29 slides up and down to change the flow passage cross-sectional area of the sub flow passage 116, and at the lower end of the sliding hole 252, the oil chamber 2e.
Is formed. The oil in the oil chamber 2e communicates with the oil chamber 2d through a small hole 230 penetrating the axial center of the valve 229.

Next, the specific portion of FIG. 5 will be described below.
The valve 231 operates up and down to change the flow passage cross-sectional area of the auxiliary flow passage 116, and at the same time, the springs 232 and 233.
Hole 2 supported in the piston rod 220 and provided in the piston rod 220.
54 is divided into oil chambers 2f and 2g. The oil in the oil chamber 2f communicates with the oil chamber 2b through a hole 234 formed in the piston rod 220. The oil in the oil chamber 2g communicates with the oil chamber 1a through a hole 235 formed in the piston rod 220, and further communicates with the oil chamber 2f through a small hole 236 penetrating the axial center of the valve 231.

The correspondence with FIG. 1 will be described below.
In both FIG. 4 and FIG. 5, the flow path resistance by the main flow paths 112, 113 provided in the main piston 111 and the sub flow path 116 formed in the piston rod 220 serves as the damper element 11. Next, the spring constant of the spring 131 brings about the effect of the spring element 13 inserted in series between the damper element 11 and the vehicle body 3, and the expansion / contraction amount e of the spring element 13 of the lower end portion 221 of the shaft 103 formed in a piston shape. Extracted as vertical movement. Further, the lower end portion 2 of the shaft 103
The mechanism in the piston rod 220 that changes the flow passage resistance of the sub flow passage 116 based on the vertical movement of the sub passage 21 corresponds to the control mechanism 2. As a result, the damping coefficient C of the damper element 11 is adjusted based on the expansion and contraction of the spring element 13.

Correspondence between the control mechanism of FIG. 2 and FIG. 4 will be further described. The vertical movement e of the lower end 221 of the shaft 103, which is obtained by extracting the expansion and contraction of the spring element 13, is caused by the closed oil chamber 2
It is converted into vertical movement m of the plunger 223 via b.
At this time, the plunger 22 is changed depending on the ratio of the upper and lower sectional areas of the oil chamber 2b.
The vertical movement m of 3 is enlarged. This is mechanism 2 of proportional constant α
Hit 01.

The vertical movement m of the plunger 223 is converted into the vertical movement 1 of the valve 229 via the spring 228.
However, in this case, as the valve 229 moves up and down, the oil chamber 2e
Oil must enter and exit the small holes 230. Therefore, a viscous resistance acts on the valve 229, and its vertical movement l cannot follow the instantaneous and rapid movement of the vertical movement m of the plunger 223. This corresponds to the first-order low-pass filter mechanism 202.

An annular groove is formed on the outer circumference of the valve 229, and the flow passage cross-sectional area of the sub-flow passage 116 in the piston rod 220 changes with the vertical movement l thereof. At this time, valve 2
The expansion / contraction amount e of the spring 131 is normally 0 in the annular groove 29.
In the case of, due to the balance of the springs 224 and 225,
It coincides with the sub-channel 116. Therefore, when the valve 229 moves up or down, the flow passage cross-sectional area of the sub flow passage 116 changes similarly. This action corresponds to 204 which performs the absolute value of the vertical movement l. Further, in this case, regardless of whether the valve 229 moves up or down, the flow passage cross-sectional area of the sub flow passage 116 decreases and the damping constant Cv of the sub flow passage 116 increases. This action increases the damping coefficient Cv in proportion to the absolute value l 205
Hit Since the damping constant Cv of the sub-flow passage 116 is increased, the damping coefficient C of the damper element 11 as a whole is also increased. This corresponds to 206.

Next, the correspondence between the control mechanism of FIG. 3 and FIG. 6 will be described. The vertical movement e of the lower end portion 221 of the shaft 103, which is obtained by extracting the amount of expansion and contraction of the spring element 13, is expanded to the vertical movement m by the vertical sectional area ratio of the oil chamber 2b. This vertical movement m
Does not appear in the mechanism inside the piston rod 220, but is transmitted as the movement of the oil in the oil chamber 2b. This corresponds to the mechanism 211 of the proportional constant α.

The vertical movement m of the oil in the oil chamber 2b is converted into the vertical movement h of the valve 231 through the hole 234. However, the valve 231 has a small hole 236 connecting the oil chambers 2f and 2g, and the springs 232 and 233 always exert a force to return to the equilibrium position. Therefore, the vertical movement of the valve 231 h
Of the oil moves up and down in the vertical movement m of the oil in the oil chamber 2b, but is gradually pushed back to the equilibrium position by the springs 232 and 233 with viscous resistance of the fine hole 236. This corresponds to the first-order high-pass filter mechanism 212.

The valve 231 is formed with two annular grooves on the outer periphery, and the piston rod 22 is moved along with the vertical movement l thereof.
The flow passage cross-sectional area of the sub flow passage 116 within 0 changes. At this time, when the expansion / contraction e of the spring 131 is 0, the two annular grooves of the valve 231 are offset vertically from the sub-flow passage 116 due to the balance of the springs 232 and 233. Therefore, when the valve 231 moves up or down, the flow passage cross-sectional area of the sub flow passage 116 changes similarly. This action corresponds to 214 which makes the vertical movement h an absolute value.

Further, regardless of whether the valve 231 moves up or down, the flow passage cross-sectional area of the sub flow passage 116 increases, and the sub flow passage 116 is
The damping constant Cv of is decreased. This action corresponds to 215 that reduces the damping coefficient Cv in proportion to the absolute value h. Then, since the damping constant Cv of the sub-flow passage 116 is reduced, the damping coefficient C as a whole is also reduced. This corresponds to 216.

As described above, the embodiment shown in FIGS. 4 to 7 shows the concrete constitution of FIG. 1 showing the basic constitution when the shock absorber of the present invention is applied to the suspension of the automobile, and further, FIGS. By realizing the control mechanism shown in FIG. 3, it is possible to realize, at a low cost, an adjusting function suitable for the suspension of the automobile with respect to the damping coefficient of the shock absorber.

Further, since the spring element 13, the damper element 11 and the control mechanism 2 are provided inside the casing 101, they are compact.

[0035]

As described above, the shock absorber of the present invention changes the damping coefficient of the damper element based on the mechanical quantity that changes according to the expansion / contraction amount of the spring element that expands / contracts according to the damping force of the damper element. Since it has a control mechanism to
The damping coefficient of the damper element can be mechanically adjusted without using the electronic detection means, the electronic adjustment means, and the electric drive actuator that operates based on the electric signal thereof, and the damping coefficient variable shock is simple in structure. An absorber can be realized.

Further, when this shock absorber is applied to an automobile suspension, the damping force of the shock absorber is in the low frequency range (usually 1 to 2) which is the resonance frequency of the vehicle body.
[Hz]), and a high frequency (normally 4 [Hz] or more), which is a problem for ride comfort, can be reduced, which provides a sufficient damping effect on the resonance of the vehicle body. At the same time, the transmission of high frequency vibrations due to the unevenness of the road surface can be reduced, and a dramatic improvement in riding comfort can be realized.

Further, it is possible to reduce power consumption and facilitate maintenance management as compared with the electronic control method.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of the present invention.

FIG. 2 is a block diagram showing an example of a control mechanism shown in FIG.

FIG. 3 is a block diagram showing another example of the control mechanism of FIG.

FIG. 4 is a cross-sectional view of essential parts showing a specific configuration example of the control mechanism of FIG.

5 is a cross-sectional view of a main part taken along the line BB of FIG.

6 is a cross-sectional view of a main part showing a specific configuration example of the control mechanism of FIG.

FIG. 7 is a cross-sectional view of the main part taken along the line BB of FIG.

FIG. 8 is a configuration diagram showing a conventional automobile shock absorber.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Shock absorber, 11 ... Damper element, 13 ... Spring element, 111 ... Main piston, 112 ... Main channel of fixed contraction side, 113 ... Main channel of fixed expansion side, 116 ... Sub flow channel, 131 ... Spring, 2 ... Control mechanism, 220 ... Piston rod, 229 and 231 ... Valve, 3 ... Car body (mass of), 4 Tire (mass of), 5 ... Spring, 6 ...
Tire spring element.

Claims (3)

[Claims] 1. A shock comprising a spring element and a damper element with variable damping coefficient connected in series, and a control mechanism for changing the damping coefficient of the damper element according to the expansion and contraction amount of the spring element. Absorber. 2. The shock absorber according to claim 1, wherein the spring element, the damper element and the control mechanism are internally provided in the same casing. 3. The control mechanism uses the damping coefficient for a low frequency component, which corresponds to a resonance frequency component of the mass, among the changes in the expansion and contraction amount of the spring element, as compared with the damping coefficient for other frequency components. The shock absorber according to claim 1, which is set to a large value.