JPS59147134A - Variable damping force type shock absorber - Google Patents

Abstract

PURPOSE:To achieve correct control for damping force by constituting the captioned apparatus so that an equal hydraulic pressure is always acts onto the both edges in the stroke direction of a valve body, thus permitting the pressure applied in the stroke direction of the valve body to be always balanced. CONSTITUTION:The spool-shaped valve body 16 is installed in slidable ways into a yoke 14, and the both edges of the valve body are set contiguous to chambers 17 and 18, and a coil 19 is set to surround the valve body 16. The both chambers 17 and 18 are allowed to communicate through the center penetration hole 16a of the valve body 16 and allowed to communicate to a pressure chamber 4 through the transverse hole 8a in a piston 8. A striped groove 16b is formed on the outer peripheral surface of the valve body 16, and a transverse hole 16c for allowing the striped groove to communicate to the penetration hole 16a is formed, and the valve body 16 is supported onto an edge cover 15 by a spring 20. A striped groove 2a is formed on the inner peripheral surface of the piston 2 into which the valve body 16 is fitted, and the communication part 21 for damping vibration whose opening degree is varied by the stroke of the valve body 16 is constituted of the striped grooves 2a and 16b, and the striped groove 2a is allowed to communicate to a pressure chamber 3 through the communication hole 2b on the piston 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shock absorber, and particularly to a variable damping force type shock absorber in which vibration damping force can be automatically controlled one by one according to operating conditions.

This type of shock absorber is usually used, for example, in
As shown in Japanese Patent No. 158111, a piston is slidably abutted in a cylinder, pressure chambers are set on both sides of the piston, and the working fluid is replaced in a limited manner between the surface pressure chambers during relative movement of the histone and the cylinder. It has a communication section that causes a flow to obtain a vibration damping effect, and is configured so that the degree of opening of the communication section can be automatically controlled by a solenoid valve to change the damping force.

However, in this case, the electromagnetic valve receives different pressures from the pressure chambers at both ends of the valve body in the stroke direction, and the pressures in these pressure chambers change one by one in a manner specific to each other during the operation of the shock absorber. , the valve body receives a force due to the difference H between the two. Therefore, is the solenoid valve controlled? The opening degree of the manual communication portion by the solenoid valve, which can be accurately responded to by TLI et al., is made inaccurate, and accurate damping force control cannot be obtained.

According to the present invention, it is possible to constantly balance the pressures applied in the stroke direction of the valve body, so that the same hydraulic pressure always acts on both ends of the valve body in the stroke direction. From the viewpoint of achieving the above-mentioned problem and solving the above-mentioned problems, the present invention aims to provide a variable shock absorber with a damping force of 0.0 cm that embodies this idea.

Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments. 11J to 3 show embodiments of the present invention, and the shock absorber of the present invention is constructed in a cylinder 1 as shown in FIGS. 1 and 2. Slideably fit the piston 2 into the piston 2.
Pressure chambers 3 and 4 are set on both sides of the cylinder 1, and a free piston 5 is slidably fitted inside the cylinder 1 to form a gas chamber 6 isolated from the pressure chamber 3. Pressure chambers 3, 4
・A non-bicompressive working fluid is inserted inside, and high-pressure gas is filled in the gas chamber 6. A piston rod 8 is connected to the piston 2 with a bolt 7, and this piston rod penetrates into the pressure chamber 4 and is slidably projected from the corresponding end of the cylinder 1 in a liquid-tight state.

A sensor 9 made of a high-quality magnetic material such as ferrite or alnico is partially exposed and embedded in the protrusion of the piston rod 8 extending in the longitudinal direction thereof, and a multipolar magnet is magnetized in the sensor. A magnetically sensitive element 10 such as a pole' element or a magnetoresistive element is provided adjacent to the sensor 9, and is attached to the cylinder l by an arm 11. The sensor 9 and the magnetic sensing element 10 constitute a stroke detector 12 for the shock absorber, and the magnetic sensing element 10 detects the sensor 9 during the relative reciprocating movement between the cylinder 1, the piston 2, and the piston rod 8, that is, during the reciprocating stroke of the shock absorber. It detects the magnetic flux possessed by the sensor and generates a sine waveform output, and this output is outputted from the lead wire 13 after passing through a waveform shaping processing circuit (not shown) and converting it into positive and negative pulse signals as shown in FIG. Pulse beliefs a and b are determined by selecting the polarity of the magnetic sensing element JO. For example, pulse signal a is output first on the extension side of the shock absorber, pulse signal A is output first on the contraction side of the shock absorber, and then pulse signals are output alternately. a and b are output.

A coil yoke 4 is protruded from the end face of the piston 2, which is faster than the piston rod 8, and its tip opening is closed with an end cover 15. Inside the yoke 14, as shown in FIG. 2, a spool-shaped valve body 16 is slidably provided at the center of the yoke 14.
A C filter 19 is provided so that both ends of the valve body 6 face the chambers 17 and 18, and are arranged to surround the valve body 16. Room 17.18
The center through hole 16a of the valve body 16 communicates between the chambers 1 and 1.
7 is communicated with the pressure chamber 4 through the horizontal hole 8a of the piston 8.

A groove 16b is formed on the outer periphery of the valve element 16, and a horizontal hole 160 is formed through the groove through the through hole 1 (ia). It is supported in the position shown in the figure.

The valve body 16 is 115: Is there a line on the inner peripheral surface of the mated piston 2? f
1\2a is provided, and the opening degree is changed by the stroke of the valve body 16 by this and the groove 16b.
section 2], the groove 2a is connected to the communication hole 2b of the piston 2.
The pressure chamber 3 is vented by this.

f, K O, lead wire 22 for energizing the coil 19
is passed through a hole 8b provided in the piston rod 8 and taken out to the outside. Further, communication holes 2C92d are formed in the piston 2, and IJ'J valves 23 and 24, which are arranged in opposite directions and also serve as a check function, are inserted into these communication holes 20.2d, respectively.

When the shock absorber of the present invention having the above-mentioned structure is used, for example, as a suspension string for a vehicle, the protruding end of the piston rod 8 is attached to the vehicle body side, and the end of the cylinder l far from this piston rod is attached to the wheel side. Although it is practical,
The power supply to the coil 19 is controlled by the circuit shown in FIG. 3, for example, and functions as follows.

That is, in FIG. 8, the shock 7' absorber stroke detector J2 outputs, for example, pulse numbers a and b shown in FIG. , this is supplied to the AND gate 25. On the other hand, the force wave generation circuit 26
In the figure, a Nokuzu square wave signal C is output, which is also an AND
The signal is supplied to the gate 25. Therefore, the AND gate 25 inputs only the H level pulse signal a to the counter circuit 27 only during the time when the square wave signal C is at the H level. The counter circuit 27 starts counting the response signal a for each chamber of the square wave signal C, and ends this counting at each falling edge of the square wave signal C. Stroke speed of each shock absorber (Xi Iis
This count (+ri is stored in memory for σ from each fall of the square wave signal C to the next fall of the launch circuit 28 of the next stage) and is supplied to the D/A conversion circuit 21 by -1°.
Ru.

The D/A converter circuit 29 converts the count value into an analog signal and inputs a signal sentence regarding the shock absorber's stroke iM+ to the arithmetic circuit 80.

Pulses a and b from the shock absorber stroke detector 12 are also supplied to a counter circuit 31), and this counter circuit counts the positive pulses (when the m number a is manually applied first). The pulse number IFt of the pulse IFt of the shock absorber pulse is 5i: When the manual force is applied first, the count value is 1. The count value corresponds to the stroke h of the shock absorber, )D
/ A conversion circuit 82 converts it into an analog signal to obtain a signal X related to the stroke amount of the shock absorber, and this signal is supplied to the calculation circuit 30 (Jj).

The arithmetic circuit 30 receives the shock absorber's stroke speed signal and stroke rate signal X, as well as the running state of the vehicle, such as rolling (steering) and hi.

Sensor 3 that detects the presence or absence of twisting (acceleration/deceleration), vehicle speed, etc.
3, and the optimum target damping force of the shock absorber is calculated from these inputs.

On the other hand, the triangular wave generating circuit 34 generates a triangular wave signal d shown in FIG.
The comparator 85 outputs a signal related to the target damping force from the arithmetic circuit 30, for example, L□, L2 or L in the 7th V.
8 signal and the triangular wave signal d from the circuit 34 are input, and as a result of their comparison, the target damping force signal is Ll,
At L2 and L8, 8. is shown in FIG. 7, respectively. Output <Rusui No. 3, indicated by f and g. These pulse signals e, f or g
When at the H level, the active transistor 36 is turned on to energize the coil 19, and the opening degree of the communicating portion 21, which is stroked by the valve body 16, is controlled by this coil as follows.

That is, when the coil 9 is de-energized, the valve body 16 is held down by the spring 20 to the position shown in FIG.
Since there is no passage between the openings of the communicating portions 21, the opening degree of the communicating portions 21 is set to zero. When the f1 state of the coil 19 is activated, the valve body 16 is attracted to one side of FIG.
The communication section 21 is opened by allowing communication between Gb and Gb. At this time, the hydraulic fluid flows from the pressure chamber 8 to the communication hole 2b, the communication part 21, and the horizontal holes 1 and 6C.
! , @pressure chamber 4 via through hole 16a, chamber 17, and side hole 8a. Alternatively, the pressure chamber 3 can be accessed from the pressure chamber 4 via the reverse route.

By the way, the opening degrees of the communication portion 21 are shown in e and f in FIG.

It is determined by the duty cycle % (proportion of H level time) of the valve switch [ ) which changes as shown in g, and when the pulse signal is e, f, and g, the average opening degree of the communicating part 21 is A.
□, A2 + A3. Therefore, the damping force of the shock absorber, which is determined by the opening degree of the 4+ passage portion 21, can be set to 1] the damping force calculated by the calculation circuit 30.

In the shock absorber of the present invention, in which the damping force is automatically controlled in this manner, when the shock absorber is stroked by an external force, the hydraulic fluid is displaced and flows under restriction through the communication portion 21 between the pressure chambers 3 and 4. The mlJ limit is determined by the opening degree of the communication portion 21, and operation with the target damping force can be performed.

That is, when the vehicle is traveling on a good road, the stroke amount signal X and the stroke speed signal are naturally small, and the arithmetic circuit 30 lowers the target damping force signal as shown by L□ in the seventh V. At this time, the output pulse signal from the comparator 35 is reduced in duty→quickle % as shown by g in FIG. do. Therefore, the vehicle can run stably. Also, at this time, the arithmetic circuit 30 also corrects the target damping force based on the signal from the sensor 33, so the damping force during turning and acceleration/deceleration is increased.
The vehicle body posture change at this time is optimized.

On the other hand, when driving on a rough road or at high speed, the stroke signal X and the stroke speed signal become large, and the calculation circuit 30 increases the target damping force signal as shown by L0 in FIG. At this time, the duty cycle % of the pulse signal from the comparator 35 is reduced as shown by e in FIG. ,. Therefore, the vehicle can run with good riding comfort even on rough roads and at high speeds. Also, at this time, the sensor 33
Since the calculation circuit 3o also corrects the target damping force based on the signal from can.

During the operation of the shock absorber, the piston rod 8 enters and protrudes from the cylinder 1, and this volume causes a change in volume within the cylinder 1, but this change in volume is usually 1j(j)l, Fat is compensated by compression and expansion of the gas in the chamber 6.

Here, when the duty control system of the coil 19 is activated and the valve body 16 keeps the communication portion 21 closed, the pressure inside the pressure chamber 3 or 4 generated during the stroke of the shock absorber is IJ 'J - The valve 23 or 24 is opened to allow hydraulic fluid to flow between the pressure chambers 3 and 4, and to prevent the shock absorber from becoming inoperable. In addition, these relief valves 23 and 24 function so that the differential pressure between the pressure chambers 8 and 4 does not exceed a certain level, so even when one of the pressure chambers 3 or 4 becomes abnormally high pressure, they will open even when there is no malfunction. It is possible to prevent the component parts of the shock absorber from being damaged and the ride comfort and handling of the vehicle from becoming extremely poor due to excessive damping force.

In addition, in the present invention, one end in the stroke direction of the valve body 16 (the chamber 17
The pressure acting on the end facing the valve body 16 is guided to the chamber 18 through the center through hole 16a, and is also applied to the other end of the valve body 16 in the stroke direction, so that the pressure applied to the valve body 16 is balanced. The valve body 16 is not subjected to any force due to the pressure applied thereto. Therefore, i71! Since the opening degree of the passage portion 21 can be controlled accurately, the damping force of the shock absorber can always be accurately controlled to the target value il+lJ, and the reliability of the variable damping force type shock absorber can be improved.

Fig. 4 shows another example of the present invention, in which the same (]; parts as in Fig. 2 are replaced by 7J''< with the same 7, 1:, 3.).

In this example, a valve guide 37 is provided protrudingly on the side of the piston 2 that is far from the piston rod 8, a groove 37a is formed on the outer periphery of the valve guide 37, and a valve body 3 made of an annular non-magnetic material is provided.
8 are slidably rotated, and these constitute a communication portion 39 that is opened and closed by the stroke of the valve body 38. The groove 87a communicates with the chamber 7 through a communication hole 87b provided in the valve guide 37, and as a result, the bottom of the east mantle 37a is connected to the communication hole 37b.
, chamber] 7 and the pressure chamber 4 through the horizontal hole 8a, and the groove 37.
The openings of a are made to pass through the pressure chambers 3, respectively.

The valve body 38 is held by the spring 4.0 as shown in the figure.
Communication part 3 covers N737a! N is 1? A pair of permanent stones 41, 4 and 2 are fitted onto the outer periphery of the valve body 38, spaced apart in the axial direction. Permanent stone 4.1 has its outer periphery magnetized to S 1jlji and its inner periphery magnetized to N pole, and permanent stone 42 has its outer periphery magnetized to N pole.
The inner periphery of hIfi is magnetized to the S pole, and a cylinder 43 made of a ferromagnetic material is fitted onto the outer periphery of these permanent magnets 41, 4, and 2. A cylindrical coil yoke 44 is arranged concentrically around the cylindrical body 43, and is attached to the piston 2 with screws 45. A pair of annular fills 4.6 are provided on the inner circumference of the yoke 44.
, 47 are attached one piece apart in the axial direction so as to face the outer periphery of the permanent magnets 4, 1, 7I, 2, and these m I #46, 4
．． 7 is surrounded by a case 48°49 of ferromagnetic material. The winding directions of the coils 46 and 47 are reversed so that when energized, adjacent ends become N poles and opposite ends become S poles.
The energizing lead wires 5o of these coils are connected to the piston rod 8.
through the hole 8b and take it out to the outside.

In the shock absorber of this example having such a configuration, the reducing force is adjusted to the target value as shown below by restricting the energization to the coils 4 and 6.47 using a circuit as shown in FIG. 5, which is similar to FIG. 3. be able to.

That is, in FIG. 5, the pulse signal e from the comparator 35
, f or g (see FIG. 7) is the transistor 51. during the H level time. , 52 are electrically connected, the coils 46.4 and 7 are energized, and the 1/14 degree angle of the communication portion 39 is controlled. That is, when the coils 46 and 47 are deenergized, the valve body 38 is moved to the position shown in FIG.
a is isolated from the pressure chamber 8. By the way, the coil 46,
470 is energized, as described above, the adjacent ends become N pole and the other end becomes S pole, so the coil 46 becomes the permanent magnet 4.1, and the coil 47 becomes the permanent magnet 42. 4
Applying a downward magnetic force in the figure, the valve body 38 is stroked in the same direction against the spring 4.0. At this time, the valve body 38 is
a to the pressure chamber 3, and open the communication part 39 to connect the W force chamber 8.
, 4. Allows hydraulic fluid to flow between.

By the way, the opening degree of the connecting part 89 is the same as in the example described above.
, is determined by the duty cycle % of the pulse signal that changes as illustrated by e, f + g in Fig. 7,
The damping force of the shock absorber, which is determined by the opening degree of the communication portion 39, can be controlled to a target value calculated by the calculation circuit 30.

In the configuration of this example as well, since the damping force control valve body 38 receives the same sweat and pressure in the force chamber 3 at both ends in the stroke direction, the force due to the pressure does not reach the valve body 88, and the damping force control described above is not performed. can be obtained accurately at all times.

In addition, if the permanent magnets 41 and 4.2 are arranged as a set of two as in this example, and the coils 46 and 47 are also arranged as a set of two, the operating force of the valve body 38 will increase. The required driving force is small, making it possible to use l1IJtt for the permanent magnets 4, 1, 4, 2 and lowering the inductance of the coil, improving the responsiveness of the damping force control action and speeding up the action. 1φ is convenient.

[Brief explanation of the drawing]

Fig. 1 is a vertical sectional side view of the shock absorber of the present invention, Fig. 2 is an enlarged sectional view of the main parts thereof, Fig. 3 is an electronic control circuit diagram of the shock absorber shown in Fig. 1, and Fig. 4 is a diagram of the shock absorber of the present invention. Figure 5 is an electronic control circuit diagram of the shock absorber shown in Figures 4 and 7. Figures 6 and 7 are shown in Figures 3 and 5. This is a time chart of each tl (signal) in the control circuit shown.■...Cylinder 2...Piston 3.4.
...Pressure '4 s... Piston four strokes 9
...Shock absorber stroke sensor 10...
Magnetic sensing element 12...Shock absorber stroke detector 14...
...Coil yoke J5...End cover 16...Valve body 19...Fill 20...Spring
21... Communication portion 23.24... Relief valve 25... AND gate 26... Square wave generation circuit 27.31... Counter circuit 2B... Launch circuit 29.32... D/ A conversion circuit 30...
Target damping force vector circuit 33...Vehicle running state detection sensor 35...Ratio 'tffl device 36. 5
1. 52...Transistor 37...Valve guide 38...Valve body 89...Communication part 4
・0...Springs 41, 42...Permanent magnet 43・
...Cylinder body 4 4...Fill yoke 46.47...Fill 4, 8, 49...Fill case. Patent applicant Nissan Motor Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] A piston is slidably fitted into the L cylinder, pressure chambers are provided on both sides of the piston, and during relative movement of the piston and cylinder, limited displacement flow of hydraulic fluid is performed between the surface pressure chambers to generate vibrations. It has a communication part that obtains a damping effect, and
In a shock absorber in which the damping force can be changed by changing the opening degree of the communicating portion by the stroke of the valve body which is automatically controlled, the pressure is constantly balanced at both ends of the valve body in the stroke direction. A variable damping force shock absorber characterized by being configured to apply the same hydraulic pressure.