JP2862776B2 - Flow control method and device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a flow rate of a working fluid in a pneumatic or hydraulic equipment.

[0002]

2. Description of the Related Art Conventionally, as a method of controlling the flow rate of a working fluid in equipment using a working fluid such as air or oil,
A method of changing the passage area of the valve and a method of changing the opening time while opening and closing the valve at a high frequency have been considered. The former is realized by a proportional control valve, a servo valve, or the like, and the latter is, for example, PWM (Pulse Width Modulatio).
(n: pulse width modulation) is realized by a two-position operation valve driven by control.

[0003]

By the way, the flow rate control method of changing the flow path area such as a proportional control valve has an advantage that a smooth flow control can be performed by continuously changing the flow path area. is there. However, such a valve utilizes a middle opening degree of the valve, that is, a state in which the valve element is disposed at an intermediate position between the fully opened state and the fully closed state of the valve. Inconveniences such as a decrease in degree are likely to occur.

On the other hand, in the flow control method utilizing the PWM control, a two-position operation valve which is always fully opened or fully closed is used. Control can be implemented. However, on the contrary, the PWM control presupposes the use of the two-position operation valve, so that the weight of the valve body cannot be increased due to the necessity of switching between opening and closing at a high speed. Since the state is discontinuously switched from the open state to the fully open state, there is a disadvantage that a large flow rate fluctuation is accompanied. Therefore, in order to avoid this inconvenience, it is necessary to reduce the size of the two-position operation valve itself, and it has been difficult to apply PWM control as a flow control of a large flow rate.

Further, even when the flow rate is controlled at a small flow rate, if the PWM control is performed by a small two-position operation valve capable of realizing the flow rate, the frequency characteristic in a high frequency range is deteriorated. However, there is a problem that it is not possible to realize flow control with desired accuracy.

The present invention has been made in view of the above circumstances, and has as its object to realize high-accuracy and large-flow rate control using PWM control.

[0007]

In order to achieve the above object, the present invention proposes the following two means. The first means is to switch one two-position operation valve serving as a reference valve from a plurality of two-position operation valves combined in parallel at a constant switching period.
In the switching period, the opening time of the reference valve is changed within the switching period based on the indicated flow rate. When the indicated flow rate is smaller than the maximum flow rate of the reference valve, the two-position operation other than the reference valve is performed. A flow control method is proposed in which the valve is closed, and when large, one or more two-position operation valves are continuously opened until the reference valve is opened , in the order of switching from the next switch to the reference valve. ing.

The second means includes a plurality of two-position operation valves combined in parallel, and control means for opening and closing the two-position operation valve, wherein the control means is provided in the two-position operation valve. Reference valve selecting means for sequentially and periodically selecting one two-position operation valve to be a reference valve, opening time setting means for setting the opening time of the selected reference valve based on the indicated flow rate, and a value of the indicated flow rate Is greater than the maximum flow rate of the reference valve, and selects one or more other two-position operation valves that are continuously opened from the reference valve next to the reference valve in order of switching. A flow control device comprising a selection means is proposed.

[0009]

According to the flow control method according to the first aspect of the present invention, one reference valve is selected from a plurality of two-position operation valves combined in parallel, and the two-position operation valve serving as the reference valve is selected. Is periodically switched, and the opening time is changed based on the indicated flow rate, so that the PWM control is performed for the entire plurality of two-position operation valves. In this case, when the indicated flow rate is smaller than the maximum flow rate of the reference valve, each two-position operation valve is selected as a reference valve only once while all the two-position operation valves are selected, and the other time. Is in the closed state, the operation cycle is the time obtained by multiplying the number of the two-position operation valves by the switching cycle, and it is possible to avoid the characteristic deterioration in the high frequency range.

Further, when the indicated flow rate is larger than the maximum flow rate of the reference valve, the flow rate is increased by opening other two-position operation valves in addition to the two-position operation valve selected as the reference valve. It is possible to do. In this case, the two-position operation valves other than the reference valve are selected in the order of switching from the next reference valve, and are opened until selected as the reference valve. The cycle is
The same as the case where the indicated flow rate is small, and similarly,
Characteristic degradation is avoided.

Further, according to the flow control device according to the second means of the present invention, when the indicated flow rate is input, the control means is operated and the two-position operating valves which are combined in parallel open and close as follows. Let me do. First, the opening time setting means is operated, and the opening time is set based on the indicated flow rate. And
By operation of the reference valve selecting means, one two-position operation valve is sequentially and periodically selected as a reference valve, and each reference valve is opened for a set opening time. As a result, the flow rate control by the PWM control is realized for the plurality of two-position operation valves as a whole, and the same flow rate as the indicated flow rate is circulated with high accuracy.

Further, when the indicated flow rate is larger than the maximum flow rate of the reference valve, the fully open valve selecting means is operated, and the two-position operation valves other than the reference valve are opened to increase the flow rate. In this case, one or more two-position operation valves are selected in the order of switching from the next reference valve, and are continuously opened until selected as the reference valve. A large flow rate can be controlled without shortening the operation cycle of the position operation valve.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the flow control method according to the present invention will be described below with reference to FIGS. The flow control method according to the present embodiment is applied to, for example, an active suspension in a railway vehicle as shown in FIG.

The active suspension has a body 1
And a plurality of cylinders 3 and 4 arranged between the trolley 2 and the bogie 2. By adjusting the air pressure supplied to the cylinders 3 and 4 in accordance with the sway of the vehicle body 1, the sway of the body 1 is controlled in real time. It is to suppress. In this embodiment, as shown in FIG. 2, a double-acting cylinder 3 driven in a vertical direction is
By arranging a double-acting cylinder 4 driven in the left-right direction at the center position of the vehicle body 1, the left and right cylinders 3 suppress the vertical movement and rolling of the body 1 by the left and right cylinders 3. The cylinder 4 can suppress left-right swinging, yawing, and the like.

The air pressure to the active suspension is adjusted and supplied to each cylinder 3 by, for example, a flow control device 5 shown in FIG. 3 provided for each cylinder 3. The flow control device 5 includes:
A plurality of solenoid valves 6 (two-position operation valves) combined in parallel, and a control device 7 (control means) for driving the solenoid valves 6
It is composed of The solenoid valve 6 includes pressure chambers 3a and 3b on the head side and the rod side of the cylinder 3, respectively.
, And four of them are configured to function as the pressure-increasing and pressure-reducing-side solenoid valves 6. In addition, the code | symbol 8 in a figure is an air pressure source.

The control device 7 controls the pressure chamber 3 of the cylinder 3
The calculator 10 calculates the air flow rate to be flowed into each of the pressure chambers 3a and 3b or the air flow rate to be flowed out from each of the pressure chambers 3a and 3b based on the pressure values from the pressure sensors 9 provided in the pressure chambers 3a and 3b. Each solenoid valve 6 is connected and opened and closed based on a flow rate command S ₁ output from the computer 10.

Hereinafter, a case in which the flow rate is controlled by the _four pressure increasing solenoid valves V _{1 to} V ₄ will be described. The flow control device 5 of the present embodiment, when it is desired to flow the air in the maximum flow rate within the flow rate of the solenoid valves 6, selects only one solenoid valve out of the four electromagnetic valves V ₁ ~V ₄ (Hereinafter, the selected solenoid valve 6 is referred to as a reference valve.) Then, the sequentially switching the solenoid valve 6 to be the reference valve at a constant period (switching period = control period) T _1, by adjusting the basis of the opening time T ₂ of the said reference valve flow command S _1, in parallel PWM control is so carried out as a whole an electromagnetic valve V ₁ ~V ₄ which are combined. That is, the indicated flow rate is Q, the solenoid valve 6
When the maximum flow rate of a single and q _max, opening time ratio w becomes w = Q / q _max (see FIG. 4).

Further, when it is desired to flow air having a flow rate larger than the maximum flow rate of each solenoid valve 6, the above-mentioned PWM control is performed while the solenoid valves 6 other than the reference valve are opened. ing. That is, the open time ratio w
Is: w = Q / q _max -i i = INT (Q / q _max ), and the i solenoid valves 6 other than the reference valve are opened at an open time ratio of 10
0% (fully open state) (see FIG. 5).

Specifically, in order to perform such a flow rate control, as shown in FIG. 3, the control unit 7 outputs a reference clock generation unit 11 for generating a reference clock, and an output from the computer 10. A logic unit 12 for converting the flow rate command S ₁ into an opening time and a switching order of each solenoid valve 6 based on the reference clock, and an output from the logic unit 12
And an amplifying unit 13 for amplifying for driving.

The reference clock generator 11 includes a reference pulse generator 11a generated at an accurate interval, and a counter 11b that counts and outputs the number of reference pulses generated by the reference pulse generator 11a. Is provided. Counter 11b includes, for example, a 9 bits, of which upper 2 bits indicate the selection information A ₁ of the reference valve, the lower 7
Bit is adapted to indicate the opening time setting information A ₂ of the reference valve. The selection information A ₁ of the reference valve and the 2 bits, because the solenoid valve 6 is composed of four set to be driven in parallel.

[0021] That is, the upper two bits of the counter 11b is, the solenoid valve _{V 1} was when "00", the solenoid valve _{V 2} is at "01", the solenoid valve V ₃ at the time of "10", "1
1 "solenoid valve V ₄ when the, selected as respective reference valve. Hereinafter, this selection order is referred to as a switching order. In addition, when increasing or decreasing the number of solenoid valves 6 may be accommodated by increasing or decreasing the number of bits of selection information A _1. And when the most significant bit switches from "1" to "0",
The computer 10 sends an interrupt signal S _2, is to request the input to the logic section 12 of the new flow command S _1.

From the computer 10 that has received the interrupt signal S ₂ , the flow rate command S ₁ calculated from information from the pressure sensor 9 and the like is converted into 9-bit designated flow rate information S ₃ by the linearization table 14. Input to the logic unit 12. The indicated flow rate information S _3, the lower 7 bits are essentially electromagnetic valve 6 single flow information B _2, and the number of fully open valve is fully opened to the upper 2 bits to realize the flow rate command S ₁ information B ₁ Is shown. That is, only the reference valve is opened and closed when the number of fully open valve information B ₁ is "00", "01", "10", when "11", the solenoid valve 6 other than the reference valve and 1-3 fully opened It is supposed to be. In the flow control device 5 of the present embodiment, a set of four solenoid valves 6 is provided on each of the pressure-increasing and pressure-reducing sides of the cylinders 3, 4, so that one bit of information for switching between them is provided. May be prepared.

The logic unit 12 stores the open time setting information A ₂ input from the reference clock generation unit 11 and the computer 10
By comparing the flow information B ₂ inputted from the side, the comparator 15 outputs an open command signal S ₄ only when the open time setting information A ₂ is smaller than the flow rate information B ₂ and (open time setting means) ,
A reference valve selector 16 to the selection information A ₁ of the reference valve based on outputs a selection signal S ₅ of the reference valve (reference valve selecting means), a selection information A ₁ Prefecture fully open valve number information B ₁ and the reference valve A full-opening selector 17 (full-opening selecting means) for selecting the solenoid valve 6 to be fully opened is provided. In FIG. 1, reference numeral 18 denotes AN.
The D circuit 19 is an OR circuit, and the entire logic unit 12 is constituted by, for example, a PLD (Programmable Logic Device).

[0024] The fully open valve selector 17, the selection information A ₁ of the solenoid valve 6 to be selected on the basis valve according switching order from the solenoid valve 6 is then selected based valve, fully open valve number information B ₁ Are selected. For example, a selection information A ₁ is "10", when fully open valve number information B ₁ is a "10", the solenoid valve 6 is then selected based valve is an electromagnetic valve V _4, it is fully opened Since the number of solenoid valves 6 is two, V ₄ and V ₁ are selected.

The amplifying section 13 is constituted by, for example, an OP amplifier circuit, and the TTL output from the OR circuit 19 is provided.
Amplify the open / close command signal S ₆ of the solenoid valve 6 at the signal level,
Is adapted to an electromagnetic valve drive signal S _7.

The operation of the flow control device 5 configured as described above will be described below. When the counter 11b highest bit falls in, the counter 11b together with the initial state, the interrupt signal S ₂ is emitted to the computer 10. When the interrupt signal S ₂ is input to the computer 10,
The flow command S ₁ from the computer 10 is input to the logic unit 12 via the linearization table 14 as 9-bit command flow information S ₃ .

First, the flow command S ₁ from the computer 10 is:
When less than the maximum flow rate of each solenoid valve 6 alone, the upper 2 bits (full open valve number information) of the indicated flow rate information S ₃ B ₁ is "0
0 ", and there is no output signal from the full-opening selection unit 17,
The solenoid valves 6 other than the reference valve are kept closed. Counter lower seven bits (open time setting information) of 11b A ₂ and the lower 7 bits of the instruction flow rate information S ₃ (flow rate information) B ₂ is compared by being inputted to the comparator 15, the opening time setting information A ₂ There only is smaller than the flow rate information B _2, open command signal S ₄ is outputted from the comparing unit 15. Meanwhile, A ₁ (selection information of the reference valve) upper two bits of the counter 11b is inputted to the reference valve selector 16, based on the selection information A _1, of one out of the solenoid valve V ₁ ~V ₄ The reference valve is selected. The reference valve selector 16 is configured to control the solenoid valve 6 selected as the reference valve.
And it outputs the reference valve selection signal S ₅ to the output terminal corresponding to.

The open / close command signal S ₆ is output from the AND circuit 18 to which the open command signal S ₄ and the reference valve selection signal S ₅ are simultaneously inputted to the amplifying unit 13, and the corresponding electromagnetic valve 6
Is opened. In this case, opening command signal S _4, since the opening time setting information A ₂ is output only when less than the flow rate information B _2, only time period based on the flow rate information B _2, reference valve is in the open state Will be. Thereafter, every time the up repeatedly the most significant bit of the opening time setting information A _2, selection information A ₂ is updated, the reference valve in accordance switching order, are sequentially switched (FIG. 4). As a result, the PWM control in the flow rate region equal to or less than the maximum flow rate of each of the solenoid valves 6 alone is performed in the entirety of the solenoid valves V _{1 to} V ₄ combined in parallel (the bottom row in FIG. 4).

Here, as shown in FIG. 4, the control cycle T ₁ of the PWM control by the flow rate control method of the present embodiment coincides with the switching cycle T ₁ of the reference valve. The cycle T ₃ is a value obtained by multiplying the switching cycle T ₁ by the number of the solenoid valves 6, so that the accuracy of the flow rate control is not affected by the performance of the solenoid valves 6 in a high frequency range, and is highly accurate. Will be maintained.

When the flow rate command S ₁ is larger than the maximum flow rate of each solenoid valve 6 alone, the above-described PWM control is performed, and based on the information B _{1 on the} number of fully opened valves and the selection information A ₁ on the reference valve. fully open valve selection signal S ₈ from the fully open valve selector 17 to the output terminal corresponding to the solenoid valve 6 Te is output, the corresponding solenoid valve 6 is fully opened. Thus, as shown in FIG. 5, in addition to the reference valve whose opening time is adjusted, the solenoid valve 6 that is fully opened over the entire switching time is provided, and the solenoid valves V ₁ to V ₁ combined in parallel are provided. as a whole V _4, of the large flow rate P
The WM control is performed (the lower part in FIG. 5).

Here, in the flow control method of the present embodiment, the solenoid valve 6 to be fully opened is selected according to the switching order from the solenoid valve 6 to be switched to the next reference valve. The selected solenoid valve 6 is continuously opened until it is closed after a predetermined opening time has elapsed after being selected as the reference valve. Accordingly, the operation cycle T ₃ of the solenoid valve 6 is the same as the operation period T ₃ in the case of the small flow rate, it is possible to implement the flow control with high accuracy.

As described above, according to the flow rate control method of the present embodiment, since the electromagnetic valve 6 that is opened and closed at a high speed is used, there is no change in characteristics over time. In addition, by combining a plurality of small flow rate solenoid valves 6 in parallel, a flow rate control of a large flow rate can be performed, and a large operation cycle T ₃ with respect to the control cycle T _{1 is provided} over the entire flow rate range. Since it is ensured, it is possible to perform smooth and highly accurate flow rate control.

In the above description, one cylinder 3.
Although only the control on the pressure increasing side of the cylinder 4 has been described, an active suspension can be constructed by applying the same thing to the pressure reducing side of the cylinders 3 and 4 and all the cylinders 3 and 4. Therefore,
The active suspension controlled by such a flow control method is driven smoothly and accurately without changing over time, effectively attenuating the vibration of the vehicle body 1, and realizing a comfortable ride comfort and durability. Is what you can do.

FIG. 6 shows an embodiment in which the flow control method according to the present invention is applied to brake pressure control. In this embodiment, which controls the flow rate of the working fluid to the brake cylinder 23 for urging the brake pad 22 on the brake disk 21 that rotates together with the wheel 20, a brake force command S ₁₀ inputted to the control device 7 , based on the sliding information S ₁₁ of the wheel 20 so as to actuate the solenoid valve 6 which is combined in parallel. In the figure,
Reference numeral 24 denotes a pressure sensor, and 25 denotes an encoder for detecting sliding.

If the flow control method of the present invention is applied to such a brake pressure control, the pressure of the brake cylinder 23 can be controlled smoothly, so that the sliding of the wheels 20 can be effectively suppressed. Become. In addition, by using the high-speed solenoid valve 6, good transient characteristics can be obtained, and the braking pressure can be changed quickly to reduce the braking force before the gliding becomes large.

As described above, the flow control method and apparatus according to the present invention are not limited to the application examples shown in the above embodiments, but are widely applied to apparatuses for performing smooth and highly accurate flow control over a wide flow rate range. What can be applied. Also, an application example using air as a working fluid has been described,
Instead, the present invention may be applied to a device that uses another working fluid such as a hydraulic pressure. Furthermore, although four solenoid valves 6 are configured to be combined in parallel, an arbitrary number of solenoid valves may be combined in parallel instead. Note that any other two-position operation valve may be used instead of the solenoid valve.

[0037]

As described above in detail, the flow control method and apparatus according to the present invention sequentially and periodically switches one reference valve selected from a plurality of two-position operation valves combined in parallel. The opening time is changed within the switching cycle, and when the flow rate is small, only the reference valve is opened, and when the flow rate is large, the reference valve is opened continuously in the order of switching from the next reference valve, so that the following effects are obtained. Since a two-position operation valve is used without using a proportional control valve that uses an intermediate opening, there is no durable change in characteristics or decrease in cleanliness of the working fluid, and durable high control performance is maintained. can do. The two-position operation valve is combined in parallel, and one reference valve whose opening time is adjusted is periodically switched, so that the operation cycle with respect to the control cycle can be secured long, and the two-position operation valve is not affected by the high frequency characteristics. Without
High-precision flow control can be performed. The two-position operation valves other than the reference valve are opened according to the flow rate, and even in the case of a large flow rate, the operation cycle of each two-position operation valve can be secured long, so that the flow rate from the small flow rate to the large flow rate High-precision flow control in a wide flow range can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a flow control method according to the present invention.

FIG. 2 is a schematic diagram showing a vehicle to which the flow control method of FIG. 1 is applied.

FIG. 3 is a view showing the active suspension of FIG. 2;

4 is a diagram showing a time chart at the time of a small flow rate in the active suspension of FIG. 3;

FIG. 5 is a diagram showing a time chart at the time of a large flow rate in the active suspension of FIG. 3;

FIG. 6 is a diagram showing another embodiment of the flow control method of the present invention.

[Explanation of symbols]

Q indicated flow rate q _max the maximum flow rate w chosen information A ₂ Open time setting information B ₁ fully open valve number information B ₂ flow rate information of the open-time ratio A ₁ reference valve S ₁ flow command S ₂ interrupt signal S ₃ indicated flow rate information S ₄ open command signal S ₅ reference valve selection signal S ₆ switching command signal S ₇ solenoid valve driving signal S ₈ fully open valve selection signal S ₁₀ braking force command S ₁₁ runway information T ₁ switching cycle, the control period T ₂ open time T ₃ operating cycle 5 flow control device 6 · V ₁ ~V ₄ solenoid valve (two-position operation valve) 7 control unit 10 computer 11 reference clock generator 12 logic 13 amplification unit 15 comparing unit (open time setting means) 16 reference valve selector ( Reference valve selection means) 17 Fully open valve selection section (Fully open valve selection means)

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G05D 7/06 G05B 11/28

Claims (2)

(57) [Claims] 1. A fixed two-position operation valve serving as a reference valve is fixedly switched from a plurality of two-position operation valves combined in parallel.
Select and open to switch sequentially in the replacement cycle ,
The opening time of the reference valve is changed within the switching cycle based on the indicated flow rate, and when the indicated flow rate is smaller than the maximum flow rate of the reference valve, the two-position operation valve other than the reference valve is closed, and when the indicated flow rate is larger, the next A flow control method, wherein one or more two-position operation valves are continuously opened until they are opened as a reference valve, in the order of switching from the one that is switched to the reference valve. 2. A two-position operation valve which is combined in parallel, and a control means for opening and closing the two-position operation valve, wherein the control means comprises one of the two-position operation valves serving as a reference valve. Reference valve selecting means for sequentially and periodically selecting the two-position operation valve, opening time setting means for setting the opening time of the selected reference valve based on the indicated flow rate, and the value of the indicated flow rate being the maximum flow rate of the reference valve. Fully open valve selecting means for selecting another one or more two-position operation valves which are continuously opened when they are larger than the reference valve next to the reference valve in the order of switching. A flow control device characterized in that: