JPH0244117Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an electromagnetic valve drive device in a fluid pressure shock absorber that changes damping force by controlling an electromagnetic valve having an electromagnetic solenoid.

[Conventional example]

In this type of variable damping force type fluid pressure shock absorber, the responsiveness when changing the damping force largely depends on the responsiveness of the electromagnetic valve. Therefore, in order to obtain a fluid pressure shock absorber with good responsiveness, a solenoid valve with improved responsiveness is required.

By the way, in order to improve the responsiveness of the electromagnetic valve, it is necessary to improve the response characteristics of the electromagnetic solenoid that operates the valve body. As an electromagnetic solenoid drive device that meets such demands, there is a conventional one disclosed in, for example, Japanese Patent Laid-Open No. 15165/1983. This device uses a single drive power source to chopper drive a solenoid that operates on DC with a pulse width modulation signal, inserts a small resistance in series with the solenoid, and uses this terminal voltage difference as a current feedback signal to drive the solenoid. It is characterized by controlling the flowing drive current so that an excessive current several times the rated value flows only at the beginning of the drive, thereby increasing the drawing speed of the solenoid. In this case, the pulse width modulation signal is formed by comparing the discharge voltage of the discharge capacitor charged to a predetermined voltage with the current feedback signal.

However, in such conventional electromagnetic solenoid drive devices, the pulse width modulation signal that drives the electromagnetic solenoid is formed using the discharge voltage of the capacitor, so it is difficult to use pulse width modulation. The electromagnetic solenoid is driven by a basic pulse when it starts operating, and when the electromagnetic solenoid finishes operating, the basic pulse is changed to a holding pulse to improve power efficiency. In this case, the holding pulse Since the holding current value is controlled to a constant value, it cannot cope with temperature rises of the electromagnetic solenoid, changes in driving voltage, etc., and these factors cause variations in the rise time of the electromagnetic solenoid. There were problems such as inability to perform accurate control and inability to ensure high-speed response.

[Purpose of invention]

This idea was created by focusing on these conventional problems, and is based on a basic pulse signal for starting the solenoid valve operation and an external signal representing factors that affect the response of the electromagnetic solenoid. By performing chopper control on a drive pulse signal formed from a holding pulse signal formed by pulse width modulation using a solenoid valve actuation command signal formed with a pulse width modulation signal based on a desired external control signal, the above-mentioned The purpose is to solve the problems of the conventional example.

[Structure of the idea]

In order to achieve the above object, this invention includes a piston that is slidably housed in a cylinder, pressure chambers defined on both sides of the piston, and a fluid passage that communicates between the two pressure chambers formed in the piston. , in a fluid pressure shock absorber in which a solenoid valve having an electromagnetic solenoid is disposed in the fluid passage and the damping force is changed by controlling the opening and closing of the solenoid valve, a basic pulse signal for starting the operation of the solenoid valve is generated. A pulse generation circuit and a first
a holding pulse signal generation circuit that generates a holding pulse signal by modulating the pulse width based on an external control signal, and a solenoid valve driving circuit that outputs a holding pulse signal following the basic pulse signal; The electromagnetic valve operation command circuit controls the circuit with an operation command signal that is pulse width modulated based on a second external control signal, and performs stepwise control of the electromagnetic solenoid.

〔Example〕

This invention will be explained below based on the drawings.

1 to 4 are diagrams showing an embodiment of this invention.

In FIG. 1, reference numeral 1 denotes a variable damping force shock absorber, in which a piston 4 attached to the tip of a piston rod 3 and a free piston 5 are slidably disposed in a cylinder 2. Pressure chamber P ₁ by piston 5,
P ₂ and P ₃ have a defined configuration. Pressure chamber P ₁
and P ₂ are each filled with incompressible hydraulic fluid,
High pressure gas is sealed in the pressure chamber _P3 . As shown in FIG. 2, the piston 4 has a central opening 7 which communicates with the pressure chamber _P1 through a liquid passage 6 bored in the piston rod 3, and a pressure chamber P2 which communicates with the central opening ₇ . A liquid passage 8 is drilled to
A spool-shaped valve element 10 having a center opening 9a and a through hole 9b, which communicates the interior of the center opening 7 with the liquid passage 8, is slidably disposed within the center opening 7. The valve body 10 is normally urged downward by the return spring 11 and is regulated by its lower end coming into contact with the bottom. In this state, the through hole 9 faces the open end of the liquid passage 8. Adopt a colander position, and then
The center opening 7 and the liquid passage 8 are in a non-communicating state. Further, the valve body 10 is moved upward by energizing and energizing the electromagnetic solenoid 12 disposed around the valve body 10, and the center opening 7 and the liquid passage 8 face each other and are in communication with each other. . and,
The valve body 10 and the electromagnetic solenoid 12 constitute a solenoid valve 13. Note that 14a and 14b are orifices on the contraction side and expansion side, and 15 is a lead wire of the exciting coil 12a of the electromagnetic solenoid 12.

Thus, the excitation coil 12a of the electromagnetic solenoid 12 of the variable damping force shock absorber 1 is driven by the drive transistor 17 driven by the drive circuit 16.
It is connected in series to the battery 19 via. Note that 20 is a surge absorbing diode connected in parallel with the exciting coil 12a.

As shown in FIG. 3, the drive circuit 16 includes a solenoid valve operation command circuit 21 that commands the operation of the solenoid valve 13.
and a solenoid valve drive circuit 22.

The electromagnetic valve operation command circuit 21 outputs a command signal A (the output waveform is shown with the same symbol in FIG. 4, and the same applies to each signal B to K below), which is a DC signal at a predetermined level. The circuit 23 and the triangular wave generating circuit 24 which outputs a triangular wave signal B of a predetermined amplitude at a relatively long predetermined cycle compare the command signal A and the triangular wave signal B, and when the triangular wave signal B exceeds the command signal A, A comparison circuit 25 outputs a comparison output with a logical value of "1" as an operation command signal C, and these constitute a pulse width modulation circuit that performs chopper control of the solenoid valve 13. Here, the command circuit 23 is configured to control the load of the vehicle, the turning of the vehicle,
A second damping force for the shock absorber 1 with a variable damping force determined by factors that affect riding comfort and steering stability such as kinematic characteristics such as pitching or rolling of the vehicle during acceleration, deceleration, sudden stopping, etc., and the environment. external signals are supplied, and a command signal A of a predetermined level is output based on these signals.

The electromagnetic valve drive circuit 22 is a basic pulse generation circuit 2.
6 and a holding pulse generation circuit 27, and supplies the basic pulse signal D of the basic pulse generation circuit 26 directly to one input side of the OR circuit 28, and also supplies it to one input side of the AND circuit 30 via an inverter 29. and the holding pulse signal H of the holding pulse generation circuit 27 is supplied to the other input side of the AND circuit 30, and its output signal I is supplied to the other input side of the OR circuit 28, and The output signal J of 28 is supplied to the other input side of an AND circuit 31 to which the operation command signal C of the solenoid valve operation command circuit 21 is supplied to one input side, and this AND circuit 2
The output signal K of 9 is supplied to the drive transistor 17 via the transistor drive circuit 32.

The basic pulse generation circuit 26 has a monostable circuit configuration that is triggered at the rising edge of the operation command signal C from the electromagnetic valve operation command circuit 21, and is a basic pulse signal for starting operation that is a rectangular wave pulse signal of a predetermined width. It is configured to output D.

The holding pulse generation circuit 27 is connected to the electromagnetic solenoid 1
Detection signals E such as the temperature rise of 2a, the temperature of the working fluid sealed in pressure chambers P ₁ and P ₂ , and battery voltage are supplied as the first external signals, and based on these, a command signal consisting of a DC signal at a predetermined level is generated. A command circuit 33 outputs a triangular wave signal F, a triangular wave generating circuit 34 outputs a triangular wave signal G of a predetermined amplitude at a predetermined period shorter than the period of the triangular wave signal B, and a triangular wave signal G is generated by comparing the command signal F and the triangular wave signal G. A comparison circuit 35 that outputs a comparison output of logical value "1" as a holding pulse signal H when the signal G becomes equal to or higher than the command signal F.
These constitute a pulse width modulation circuit.

Next, the effect will be explained. Now, an external signal is supplied to the command circuit 23 of the operation command circuit 21 to maintain the variable damping force shock absorber 1 at a low damping force, for example when driving straight on a good road. In FIG. 4a, a relatively low level command signal A is output as shown by the chain line, and this is sent to the comparison circuit 25 and sent to the triangular wave generation circuit 2.
4 is compared with the triangular wave signal B shown by the solid line in FIG.
Assume that is output. Further, a predetermined detection output E is supplied to the holding pulse generation circuit 27,
In response to this, it is assumed that the command signal F of a predetermined level is outputted from the command circuit 33 as shown by the chain line in FIG. It is assumed that the holding pulse signal H having a predetermined duty ratio shown in FIG. 4d is outputted from the comparison circuit 35 since it is compared with the triangular wave signal G shown by the solid line at point c.

For example, the operation command signal A has a logical value of "0".
At a certain time t1, the basic pulse signal D of the basic pulse generating circuit 26 also has a logical value of "0" as shown in FIG. 4e. Therefore, from the AND circuit 30, the fourth
As shown in FIG.
It is supplied to the AND circuit 31. however,
Since the operation command signal C supplied to one input side of the AND circuit 31 has a logical value of "0", this
The output signal K of the AND circuit 31 maintains the logical value "0" as shown in FIG.
7 is maintained in the off state, and the electromagnetic solenoid 12
The excitation coil 12a is in a non-excited state.

As a result, the electromagnetic solenoid 12 is maintained in a non-energized state, so that the valve body 10
Due to this force, it assumes a sliding position in which it slides downward as shown in FIG. 2, and the liquid passages 7 and 8 become misaligned, and the liquid passages 7 and 8 are cut off. Therefore, the pressure chambers _P1 and _P2 are communicated only through the orifices 14a and 14b.
The fluid resistance between the pressure chambers _P1 and _P2 increases, and the damping force of the variable damping force shock absorber 1 becomes the highest.

From this state, when the operation command signal C becomes a logical value "1" at time t2, the basic pulse generation circuit 26 is triggered at this rising time, and the basic pulse signal D becomes a logical value "1" as shown in FIG. 4e. 1”. Therefore, the output signal I of the AND circuit 30 has a logical value of "0" as shown in FIG.
The OR circuit 28 outputs an output signal J having a logical value of "1" based on the basic pulse signal D as shown in FIG. 4g. Therefore, the AND circuit 31 outputs an output signal K with a logical value of "1" as shown in FIG. Ru. As a result, the electromagnetic solenoid 12
Since the excitation current from the battery 19 is applied to the excitation coil 12a, the electromagnetic solenoid 12 is excited, and the valve body 10 of the electromagnetic valve 13 is attracted with its flange portion 10a against the return spring 11. and start moving upward. At this time, the exciting current from the battery 19 is continuously supplied to the exciting coil 12a, so the electromagnetic solenoid 12a
The driving force for moving the valve body 10 against the return spring 11 is set to be large, so that the valve body 10 can be moved quickly.

Then, when a predetermined time sufficient to complete the movement of the valve body 10 of the solenoid valve 13 has elapsed, the basic pulse signal D of the basic pulse generating circuit 26 returns to the logical value "0" at time t3, and therefore, the AND The holding pulse signal H from the holding pulse generation circuit 27 is output again from the circuit 30, and this is passed through the OR circuit 28.
Since the signal is supplied to the AND circuit 31, the output signal K based on the holding pulse signal H instead of the basic pulse signal D is supplied from the AND circuit 31 as shown in FIG. 4h.
is output. As a result, a pulse drive signal is output from the transistor drive circuit 32, and the drive transistor 17 is subjected to chopper control. For this reason,
As shown in FIG. 4i, the current flowing through the exciting coil 12a is at a low level compared to the current value when the solenoid valve 13 starts operating, and the valve body 10 of the solenoid valve 13 is held against the return spring 11. The current is kept at a minimum value sufficient for In this way, the solenoid valve 13
When the valve body 10 is moved upward against the return spring 11, the liquid passages 7 and 8 are communicated with each other through the through hole 9, so that the fluid resistance between the pressure chambers _P1 and _P2 is reduced. , the damping force of the variable damping force shock absorber 1 is reduced.

Thereafter, when the operation command signal C from the electromagnetic valve operation command circuit 21 changes to the logical value "0" at time t4 as shown in FIG. 4b, the output signal K of the AND circuit 31
becomes the logical value "0" as shown in FIG.
The damping force of the variable damping force shock absorber 1 is increased.

In this way, the variable damping force shock absorber 1
As described above, the damping force of the solenoid valve 13 is changed by operating the solenoid valve 13 based on the operation command signal C from the operation command circuit 21, and the damping force of the solenoid valve 13 is changed according to the duty ratio of the operation command signal C. When the valve opening degree is determined and the duty ratio of the operation command signal is large as described above, the valve opening degree of the solenoid valve 13 is determined as shown in FIG.
As shown by the chain line, the damping force of the variable damping shock absorber 1 is controlled to about 75% of the fully open state, thereby reducing the damping force of the variable damping force shock absorber 1 and improving the ride comfort of the vehicle.

From this state, for example, at time ta, when the vehicle turns, suddenly accelerates or decelerates, and it is necessary to increase the damping force of the variable damping force shock absorber 1, an external signal representing this is supplied to the command circuit 23. Ru. Therefore, the command signal A of the command circuit 23
is at a high level as shown by the chain line in FIG. 4a, so the comparator circuit 25 outputs an operation command signal C with a small duty ratio as shown in FIG. The valve opening is set to about 25%, and the overall damping force of the variable damping force shock absorber 1 is increased.

Further, when the holding current supplied to the excitation coil 12a by the holding pulse signal H from the holding pulse generation circuit 27 maintains a constant value, the attraction force of the solenoid valve 13, the spring force of the return spring 11, and the valve body 10 The balance point with frictional resistance, etc. is the solenoid valve 1.
Due to the influence of the temperature rise of the excitation coil 12a of No. 3, changes in fluid temperature, voltage fluctuations of the battery 19, etc.
As a result, the falling time of the electromagnetic solenoid 12 varies. Therefore, in this invention, in order to prevent the above-mentioned variations in the falling time of the electromagnetic solenoid 12, factors that affect the operation of the electromagnetic solenoid are detected by a predetermined detector, and the detection signal E is detected. The command signal F is input to the command circuit 33 of the holding pulse generation circuit 27, and the command circuit 33 outputs the command signal F, which is a DC level signal corresponding to the detection signal E. For example, the command signal F is input at time ta. When the level becomes high as shown by the chain line in FIG. 4c, the duty ratio of the holding pulse signal H output from the comparator circuit 35 becomes small as shown in FIG. 4d, and the holding current value is lowered to optimize it. The value can be controlled.

Further, a variation in the responsiveness of the electromagnetic valve 13 can be considered to be a flow force expressed by a component force in the valve element operating direction of a force corresponding to the momentum of the fluid passing through the valve element 10.

Generally, the flow force of a valve body like the one in this embodiment can be expressed as in the following equation.

F _f = ρ・Q/V・cosθ Where, F _f ; Steady fluid force component of flow force (acts in the direction of closing the valve body) ρ : Working fluid density Q; Flow rate passing through the valve body opening V; Jet flow at the valve body opening Velocity (V=Q/A, A; Valve body opening area) θ; Jet angle (θ≒69°, cosθ≒constant) Now, let the piston speed in the shock absorber 1 be V _p and the pressure receiving area be A _p . For example, Q=A _p・V _p・α where α; valve body 10 and orifice 14a, 1
Distribution of flow rate flowing through 4b (α≦1.0) Therefore, the relationship between the flow force of the valve body 10 and the piston speed is as shown in the following equation.

F _f = ρ・(A _p・V _p・α) ・[A _p・V _p・α/A]・cosθ =ρ・A _p ²・α ²・cosθ/A・V _p ² ≒k・V _p ² (k is a constant) In other words, the flow force is expressed as a function of the piston speed, and has variations depending on the piston speed.

Therefore, the response time of the valve body 10 also varies depending on the piston speed, so by detecting the piston speed and supplying it to the command circuit 33, the response time can be made to depend on the piston speed. The holding current may also be controlled.

Note that in the above embodiment, the basic pulse signal D
Although the case where is a rectangular wave signal having a predetermined pulse width (here, rectangular wave signal means that the pulse width is defined by a certain time width) has been described, the present invention is not limited to this. A pulse signal with a larger duty ratio than the holding pulse signal H of the holding pulse generation circuit 27 (the pulse signal here is a pulse signal having the same period as the holding pulse signal H, and is defined by the duty ratio of the pulse width) 1 first pulse signal (herein, 1 first pulse signal means the first pulse of a pulse signal with a large duty ratio that rises after the rise of the command signal)
can also be used as the basic pulse signal D of the above embodiment, and as a result, a drive current waveform similar to that of this embodiment can be obtained.

Furthermore, the AND circuit 31 of the solenoid valve drive circuit 22 is
It may be provided between the holding pulse generation circuit 27 and the AND circuit 30 or between the AND circuit 30 and the OR circuit 28, and the circuit configuration is equivalent, and as a result, a drive current waveform similar to that of this embodiment can be obtained.

Furthermore, the variable damping force shock absorber 1 as a liquid pressure shock absorber is not limited to the above-mentioned configuration, and the variable damping force shock absorber 1 is not limited to the above-mentioned configuration, but has a pressure chamber defined by a piston.
Needless to say, this invention can be applied to any structure in which the electromagnetic valve 13 is disposed in the fluid passage communicating between P ₁ and P ₂ .

[Effect of idea]

As explained above, according to this invention, the drive current supplied to the electromagnetic solenoid constituting the electromagnetic valve is adjusted so as to obtain the desired valve opening according to the actuation command signal from the electromagnetic valve actuation command circuit. At the same time, the operation command signal itself is formed by a basic pulse signal for starting solenoid valve operation and a holding pulse signal following this, and the holding pulse signal is converted into an external input signal representing a factor that affects the operation of the electromagnetic solenoid. Since the electromagnetic solenoid is formed by pulse width modulation based on the pulse width modulation, it improves power efficiency while preventing the effects of internal resistance due to temperature rise of the electromagnetic solenoid, fluctuations in drive voltage, and fluctuations in fluid temperature. The holding current can be controlled to an optimum value, the fall time of the solenoid valve can be shortened, and the responsiveness of the hydraulic shock absorber can be improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of this invention.
Fig. 2 is an enlarged sectional view of the piston portion, Fig. 3 is a block diagram showing one embodiment of the drive circuit, and Fig. 4 is a block diagram showing an embodiment of the drive circuit.
The figure is a signal waveform diagram of each part to explain the operation of this invention. 1... variable damping force shock absorber, 12...
...Electromagnetic solenoid, 12a...Excitation coil, 13
... Solenoid valve, 16 ... Drive circuit, 17 ... Drive transistor, 19 ... Battery, 21 ... Operation command circuit, 22 ... Solenoid valve drive circuit, 23 ...
Command circuit, 24...triangular wave generation circuit, 25...comparison circuit, 26...basic pulse generation circuit, 27...
Holding pulse generation circuit, 33... Command circuit, 34...
...Triangular wave generation circuit, 35... Comparison circuit.

Claims (1)

[Scope of utility model registration request] A piston is slidably housed in a cylinder to define pressure chambers on both sides thereof, a fluid passage communicating between both pressure chambers is formed in the piston, and an electromagnetic valve having an electromagnetic solenoid is installed in the fluid passage. The hydraulic shock absorber is arranged to change the damping force by controlling the opening and closing of the solenoid valve, a basic pulse generating circuit generating a basic pulse signal for starting the solenoid valve operation, and a first external control signal. a holding pulse signal generation circuit that generates a holding pulse signal by pulse width modulation based on the basic pulse signal, and a solenoid valve driving circuit that outputs a holding pulse signal following the basic pulse signal; 1. A solenoid valve drive device for a fluid pressure shock absorber, comprising: a solenoid valve operation command circuit that performs stepwise control of the electromagnetic solenoid by controlling the solenoid valve with an operation command signal that is pulse width modulated based on an external control signal.