JP2002149242A - Flow rate control system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow rate control system which properly control a flow rate according to the load state of an operation part. SOLUTION: In the flow passage 2 from a hydraulic pressure source 1 to the operation part 3, a proportional control valve 42, a first pressure detecting means 43, a differential pressure generation part 44, and a second pressure detecting means 45 are arranged in order and an electronic circuit 41 is also added which detects the flow rate Q according to their detected pressure values P1 and P2 and controls the proportional control valve 42, so that the flow rate Q is determined according to the pressure P2. Thus, flow rate characteristics can optionally be set through the processing of the electronic circuit and the pressure detecting means needed for that are used to reflect the load state of the operation part, so the target flow rate control system is easily actualized. Further, control is so performed that the flow rate Q is made constant as the pressure P2 exceeds a pressure value B and decreased as the pressure drops below the pressure value B, this system is made suitable for the hydraulic pressure driving of a chemical pump, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate control system for controlling a flow rate of a pressure liquid supplied from a hydraulic pressure source to an operation section, and more particularly, to a flow rate control for controlling a flow rate according to a load state of an operation section. About the system.

[0002]

2. Description of the Related Art Conventionally, in order to control the flow rate of a pressure liquid such as hydraulic pressure, a flow control valve is used in many cases. However, depending on the application, it may be difficult to use the flow control valve. For example, when it is desired to variably control the flow rate according to the load state of the operating unit, for example, by connecting a hydraulic motor to a chemical pump and performing a hydraulic drive thereof, a servo valve may be used to perform flow rate control instead. is there.

[0003]

However, the servo valve has a high performance but is expensive. In addition, since the pressure liquid is susceptible to dust and the like, it is necessary to keep the pressure liquid in a clean state at all times, and the maintenance cost tends to be high. For this reason, it is desirable to avoid using servo valves if possible. Therefore, when the flow control valve is difficult to use, in order to substitute flow control using something other than the servo valve, the technical problem is what kind of valve is used and how it is controlled. . The present invention has been made to solve such a problem, and an object of the present invention is to realize a flow control system that appropriately controls a flow according to a load state of an operating unit.

[0004]

Means for Solving the Problems First and second solving means invented to solve such problems are as follows.
The configuration and operation and effect will be described below.

[First Solution] A flow control system according to the first solution is as described in claim 1 at the beginning of the application.
(For supplying the pressurized liquid) from a hydraulic source (operating in response to the pressurized liquid) to a working unit (for supplying the pressurized liquid)
A proportional control valve, a first pressure detecting unit, a differential pressure generating unit, and a second pressure detecting unit are arranged in order with respect to the flow path, and their detected pressures (that is, the first pressure from the first pressure detecting unit) are determined. An electronic circuit for detecting the flow rate (for the pressure liquid in the flow path) based on the detected pressure and the second detected pressure from the second pressure detecting means and controlling the proportional control valve is also provided, (By control of this electronic circuit)
The flow rate is determined according to the pressure detected by the second pressure detecting means.

In such a flow control system of the first solution, the differential pressure in the differential pressure generating section is determined from the first and second detected pressures, and the differential pressure and the characteristics of the differential pressure generating section are determined. The flow rate is detected, a target value of the flow rate is determined from the value and the second detected pressure, and the control content and control amount for the proportional control valve are determined from the detected value and the target value of the flow rate. Done by Then, the necessary pressure is detected by the first and second pressure detecting means before and after the differential pressure generating unit, and the processing result of the electronic circuit is reflected on the actual flow rate via the proportional control valve.

Thus, the flow characteristics can be easily set arbitrarily by appropriately determining the processing content of the electronic circuit. In addition, since the second pressure detecting means is disposed immediately upstream of the operating section, and the second detected pressure reflects the load state of the operating section, the flow rate is detected when determining the processing content of the electronic circuit. In addition to the use of the second detection pressure when determining the target value of the flow rate, as well as taking into account the characteristics of the operating section, it can easily respond to and adapt to changes in the load state of the operating section, etc. Control can be performed. Therefore, according to the present invention, it is possible to easily realize a flow control system that appropriately controls the flow according to the load state of the operating unit.

[Second Solution] A flow control system according to a second solution is the flow control system according to the first solution, wherein the electronic circuit of the electronic circuit is provided. Based on the control, when the detected pressure of the second pressure detecting means exceeds a predetermined threshold value, the flow rate is kept constant, and when the detected pressure of the second pressure detecting means falls below the threshold value, the flow rate is accompanied. Thus, the flow rate is also reduced.

Alternatively, as described in claim 3 at the beginning of the application, a hydraulic pressure source (for supplying the pressurized liquid) to an operating section (for receiving and receiving the pressurized liquid) (for supplying the pressurized liquid). A) a proportional control valve interposed in the flow path, a differential pressure generating section interposed in the flow path on the downstream side thereof, and a differential pressure generating section interposed between the proportional control valve and the differential pressure generating section. A first pressure detecting unit that measures a pressure in the flow path (the pressure liquid in the flow path) and also outputs a signal of a first detection pressure, and a flow path in the flow path between the differential pressure generating unit and the operating unit. A second pressure detecting means for measuring the pressure of the pressure liquid and also outputting a signal of the second detected pressure; and inputting the first detected pressure and the second detected pressure and detecting the pressure in the flow path based on the input. The flow rate of the pressurized liquid) and based on it A control signal for the proportional control valve is generated and sent to the proportional control valve.When the control signal is generated, the flow rate becomes constant when the second detection pressure exceeds a predetermined threshold, and the flow rate becomes constant. (2) an electronic circuit for determining the content of the control signal so that when the detected pressure falls below the threshold value, the flow rate is reduced accordingly.

In the flow control system according to the second solving means, the setting of the flow characteristic is embodied in addition to the above-mentioned second solving means. That is, when the second detection pressure reflecting the load pressure of the operating unit exceeds a predetermined threshold, the flow rate of the pressure liquid supplied to the operating unit is kept constant, and when the pressure falls below the threshold, the As the pressure drops, the flow rate is also reduced.

[0011] In the case where the operating part in which a hydraulic motor is connected to a chemical pump is driven by hydraulic pressure, galling is likely to occur if the chemical pump continues to rotate at a high speed and a constant speed even if there is no liquid to be pumped out. Where there is inconvenience
When the pumping liquid decreases and almost disappears, the load is reduced, which is reflected in the load pressure, that is, the second detection pressure, and the flow rate of the pressure liquid supplied to the hydraulic motor is also reduced accordingly. Since the rotation of the chemical pump also gradually decreases, the pumping operation is completed without generating galling or the like. Before that, i.e., while the pumped liquid remains to a certain extent or more, stable pumping is performed at a constant speed.

As a result, the hydraulic drive of the chemical pump is automatically and accurately performed. In addition, the processing can be easily performed by appropriately determining the processing content of the electronic circuit in accordance with the characteristics of the chemical pump and the like. Therefore, according to the present invention, a flow control system suitable for hydraulic drive of a chemical pump or the like can be easily realized.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Several embodiments for implementing the flow control system of the present invention achieved by such a solution will be described.

[First Embodiment] A first embodiment of the present invention is a flow control system of the above-mentioned solution means as described in claim 4 at the beginning of the application, wherein the proportional control valve is A proportional pressure reducing valve for variably controlling the downstream pressure is employed. Alternatively, a proportional throttle valve for variably controlling the opening is adopted as the proportional control valve.
Thus, the variable control of the flow rate can be easily and accurately performed by the feedback control of the electronic circuit based on the detected pressure without using the flow control valve. In addition, by using such feedback control, the accuracy of the proportionality in the proportional control valve is not required to be strict because the pressure and the opening degree only need to be clearly increased and decreased with the increase and decrease of the control amount.
Inexpensive popular products can also be used for the proportional control valve.

[Second Embodiment] A second embodiment of the present invention is a flow control system according to the above-mentioned solving means, as described in claim 5 at the beginning of the application, wherein the proportional control valve is It has an upstream port, a downstream port, and a return port to a tank or the like to variably control the pressure on the downstream side and at the control limit in the direction of decreasing the pressure on the downstream side, the return port and the downstream port are A proportional pressure reducing valve for communication is employed. Alternatively, the proportional control valve has an upstream port, a downstream port, and a return port to a tank or the like, and variably controls an opening degree in a communication portion between the upstream port and the downstream port, and performs the upstream control. When the communication between the side port and the downstream port is cut off, a proportional three-way valve for communicating the return port with the downstream port is employed.

In this case, if the flow rate is controlled so as to be at the lower limit of the variable range, the excess pressure liquid in the flow path recirculates to the tank and the like, and the driving pressure on the operating portion is completely eliminated. Since the operating part stops in a state of static equilibrium, it is possible to easily and reliably prevent the occurrence of undesired situations such as unnecessary operations being performed at the end of operation or subsequent maintenance work etc. can do.

[Third Embodiment] A third embodiment of the present invention is a flow control system according to the above-mentioned solving means and the embodiment as described in claim 6 at the beginning of the application, wherein the differential pressure That is, a generator in which a variable aperture is connected to a fixed aperture is adopted as the generation unit. When there is a variation in the throttle amount of the fixed throttle for each device embodying the flow control system of the present invention, by adjusting the throttle amount of the variable throttle, the combined value of the throttle in the differential pressure generating unit of each device can be adjusted. It is possible to align. As a result, the adjustment work for eliminating the machine difference regarding the characteristics of the differential pressure generating section can be easily performed.

[Fourth Embodiment] A fourth embodiment of the present invention is the flow control system according to the above-described embodiment, as described in claim 7 at the beginning of the application, wherein the differential pressure generating unit is , And can be collectively attached to and detached from the flow path. This is convenient because the operation of adjusting the throttle amount of the differential pressure generating unit can be performed at a place different from the actual machine that embodies the system, and can be performed collectively. .

With respect to the flow rate control system of the present invention achieved by the above-mentioned solution means and embodiments, specific embodiments for implementing the flow rate control system will be described with reference to the following first to fifth embodiments. The first embodiment shown in FIGS. 1 and 2 is similar to the first and second solving means and the first embodiment described above (the first claim 1 to claim 1).
4) is embodied, and the second embodiment shown in FIG. 3 is the same but another example. In addition, the third embodiment shown in FIG.
The fourth embodiment shown in FIG. 5 embodies the embodiment and (initial claims 1 to 3 and 5). The fourth embodiment shown in FIG. (Initial Claim 1 ~
7) is embodied, and the fifth embodiment in FIG. 6 is a modification thereof. In addition, for the sake of simplicity and the like, a symbolic diagram and a block diagram are frequently used for the illustration,
The hydraulic main line is shown by a thin solid line, the hydraulic pilot line is shown by a thin long broken line, and the electric signal line is shown by a thin two-dot chain line. In addition, illustration of the return line from the hydraulic motor to the tank and the like are omitted.

[0020]

First Embodiment A first embodiment of a flow control system according to the present invention will be described with reference to the drawings. FIG. 1 shows an outline thereof, and FIG. 2 is a more specific example. In each case, (a) is a circuit diagram of a hydraulic circuit or the like showing an entire structure, and (b) shows an operation characteristic. It is a pressure-flow characteristic diagram shown.

In short, this flow control system (FIG. 1)
(A)), when the pressure liquid for driving is supplied from the hydraulic pressure source 1 to the operating section 3, the flow rate Q of the pressure liquid is controlled. The following flow control unit 40 is provided for the flow path 2 for supplying the pressure liquid to 3. That is, the flow control unit 40 is often integrated by an appropriate manifold block or the like, where the proportional control valve 42 is interposed and connected in order from upstream to downstream along the flow path 2, and the first pressure The detecting means 43 is connected so as to be able to receive pressure, the differential pressure generating section 44 is inserted and connected, and the second pressure detecting means 45 is connected so as to be able to receive pressure. Furthermore, an electronic circuit 41 is provided, which comprises a proportional control valve 42, a first pressure detecting means 43 and a second pressure detecting means 4
5 are connected to each other via an appropriate cable or the like so that signals can be transmitted and received.

With the above arrangement and connection, the pressure of the pressure liquid in the flow path 2 between the proportional control valve 42 and the differential pressure generating section 44 is measured by the first pressure detecting means 43, and the detection result is obtained. Is the electronic circuit 41.
And the pressure of the pressurized liquid in the flow path 2 between the differential pressure generating section 44 and the operating section 3 is also measured by the second pressure detecting means 45, and the detected pressure P2
(Second detected pressure) is also sent to the electronic circuit 41 as a signal. Further, the pressures P1 and P2 are input to the electronic circuit 41, and the electronic circuit 41 performs predetermined calculations and the like, and based on the pressures P1 and P2, the flow rate Q in the flow path 2
Is detected, a control signal S for the proportional control valve 42 is generated based on the detected value of the flow rate Q, and the control signal S is sent to the proportional control valve 42. When the pressure P2 exceeds a predetermined pressure value B (threshold value), the proportional control valve 42 performs variable control on the flow rate Q according to the control signal S, so that the flow rate Q becomes a constant flow rate value A.
When the pressure P2 falls below the pressure value B, the flow rate Q also decreases accordingly (see FIG. 1B).

More specifically, as shown in FIG. 2 (a), a typical hydraulic pressure source 1 employs a hydraulic pump driven by an electric motor, a motor, or the like, and an appropriate oil tank or relief valve (not shown). Etc. are also attached. This may be shared with another hydraulic circuit or the like depending on the application. Channel 2
Is an appropriate metal pipe, a rubber hose reinforced with a metal mesh, etc., a perforation formed in the manifold block,
A joint, a passage in the valve, and the like are formed in series, and pass all or a part of the oil, which is the pressure liquid discharged from the hydraulic pressure source 1, to guide the oil to the operating unit 3.

The operating section 3 is provided with a hydraulic motor 3a having an input port connected to the flow path 2 and an output port (not shown) connected to a tank side pipe or the like, and a rotary output shaft of which is connected to an input shaft of the chemical pump 3b. The hydraulic motor 3a and the chemical pump 3 are connected at a rotational speed corresponding to the flow rate Q.
b operates. Chemical pump 3b
Is used that is adapted to the characteristics of the pumping liquid 3c to be pumped out. For example, the pumping liquid 3c is made of a material that does not react to a special chemical or the like even if it is a special chemical.
Since there are many restrictions on the use of the lubricating oil and the like, undesired galling is likely to occur when the rotation is continued at a high speed in an empty state where the pumped liquid 3c has disappeared from the container or the tank.

As the proportional control valve 42, for example, an electromagnetic proportional pressure reducing valve is employed, and the downstream side pressure P1 which is the secondary side pressure thereof is used.
Is variably controlled. That is, the electromagnetic proportional pressure reducing valve uses the secondary pressure as the pilot pressure and balances the pilot pressure with the thrust of the electromagnet which is substantially proportional to the control signal S. An inexpensive fixed throttle is used for the differential pressure generating section 44, and the pressure difference between the front and rear is clearly expressed even when the flow rate Q is equal to or less than the flow rate value A, under the condition that the pressure difference is apparent. In other words, the throttle amount and the throttle amount are such that the differential pressure is as small as possible.

The first and second pressure detecting means 43 and 45 include:
An appropriate pressure gauge can be used if the performance and accuracy are sufficient. However, in order to enable signal output of the pressures P1 and P2, a pressure gauge with piezoelectric conversion means is employed. Although not essential, it is preferable that a differential output amplifier, for example, is incorporated for signal amplification and noise suppression. Electronic circuit 41
May be an analog or digital arithmetic circuit specially designed, but in this example, a general-purpose microprocessor 41
The processing contents can be flexibly determined by a program by adopting b.

That is, the microprocessor 41b includes:
According to the program processing, the flow rate value A, the pressure value B, and the cutoff pressure C are input from each of the setting devices 41a and the like installed on the operation panel and the like, and the pressures P1 and P2 are also transmitted through an appropriate A / D conversion circuit 41c and the like. Input regularly or irregularly,
The control signal S to the proportional control valve 42 is generated based on these values. At the time of the calculation (see FIG. 2B), the flow rate Q is calculated from the differential pressure (P1-P2) based on the characteristics of the differential pressure generating section 44,
The flow control characteristic of the flow rate Q
In order to adapt to the characteristic of b, the proportional control valve 42 changes the pressure P1 according to the control signal S, so that when the pressure P2 exceeds a predetermined pressure value B (threshold), the flow rate Q becomes a constant flow rate value A, When the pressure P2 falls below the pressure value B, the content / value of the control signal S is determined based on the characteristics of the proportional control valve 42 based on the flow rate Q and the pressure P2 so that the flow rate Q decreases accordingly. I have. Further, in the event of an abnormality in which the pressure P1 exceeds the cutoff pressure C, the flow rate Q is quickly reduced in order to prevent an unexpected situation from occurring.

The usage and operation of the flow control system according to the first embodiment will be described.

When the hydraulic pressure source 1 and the flow control unit 40 are operated in the state where the pumped liquid 3c is present, the flow Q increases from zero, and the rotation of the hydraulic motor 3a and the chemical pump 3b is accelerated accordingly. Then, the pumped liquid 3c to be pumped becomes a load, and the pressure P2 increases, and the control signal S and the pressure P1 also increase at a rate exceeding the pressure P2.
Such an increase is repeated until the pressure P2 reaches the pressure value B.

When the pressure P2 reaches the pressure value B,
The increase in the flow rate Q is suppressed, and the flow rate Q is kept constant at the flow rate value A while the pressure P2 is between the pressure value B and the cutoff pressure C. Since the load state of the working unit 3 changes due to a change in the head pressure of the pumping liquid 3c, the pressure P2 increases and decreases, but as long as the pumping liquid 3c is sufficient, the pumping liquid 3c is stably pumped by a fixed amount. .

Eventually, when the pumping liquid 3c is almost pumped out and its head pressure drops considerably, the pressure P2 also drops and falls below the pressure value B. Then, contrary to the start of the operation, the flow rate Q and the pressure P2 interact with each other and descend repeatedly, and finally both become zero. Thus, when the pumping liquid 3c is low and caution is required for the chemical pump 3b, the rotation speed of the chemical pump 3b is automatically reduced in accordance with the degree of danger. Will be completed.

[0032] In addition, in the unlikely event that swelling occurs,
(c) When the load becomes excessively heavy due to the clogging of the feed hose, the pressure P2 also increases greatly reflecting this. Then, when the load state changes so that the pressure P1 exceeds the cutoff pressure C, the flow rate Q is rapidly reduced, and the rotations of the hydraulic motor 3a and the chemical pump 3b are also rapidly reduced. In this way, even if an abnormal situation occurs, it is surely prevented from worsening.

[0033]

Second Embodiment The flow control system of the present invention whose circuit diagram is shown in FIG. 3 is different from that of the first embodiment described above.
The point is that a proportional throttle valve is employed for the proportional control valve 42. The proportional throttle valve is configured such that a movable member such as a spool that determines the throttle opening is connected to an electric member such as a pulse motor so that the throttle opening can be variably controlled by a control signal S. Further, in order to transmit the control signal S as a digital signal suitable for a pulse motor or the like, the electronic circuit 41 employs an appropriate interface or driver such as a digital output circuit 41e.

In this case, the control signal S indicates the opening of the proportional control valve 42 instead of the pressure P1, but the control signal S
Since the relationship that the flow rate Q increases or decreases in response to the increase or decrease is maintained, repeated detailed description is omitted, but the feedback control via the electronic circuit 41 also performs the above-described first embodiment. An operation result similar to that of the example is obtained.

[0035]

Third Embodiment The flow control system of the present invention whose circuit diagram is shown in FIG. 4 is different from that of the above-described first embodiment in that:
The point is that a proportional three-way valve is adopted as the proportional control valve 42. This proportional three-way valve has an electromagnetic drive unit added to a three-way valve having an upstream port, a downstream port, and a return port to a tank or the like, and performs port switching substantially in proportion to the value of the control signal S. The position of the application spool is changed continuously and analogously. When the value of the control signal S is large, the opening degree at the communication portion between the upstream port and the downstream port is variably controlled, and when the value of the control signal S is zero, the connection between the upstream port and the downstream port is The communication is cut off to connect the return port and the downstream port.

In this case, substantially the same operation result as that of the above-described second embodiment can be obtained. However, when the flow rate Q is reduced to zero or close to it at the end of the pumping operation or at the time of other abnormalities, the flow path The pressure liquid trapped in 2 gradually and surely returns to the tank side, thereby releasing excess pressure, so that the hydraulic motor 3a and the chemical pump 3b stop gently in a natural state.

[0037]

Fourth Embodiment A specific configuration of a fourth embodiment of the flow control system of the present invention will be described with reference to the drawings. FIG. 5A is a circuit diagram of a hydraulic circuit or an electronic circuit showing the entire structure, and FIG. 5B is a pressure-flow characteristic diagram showing operating characteristics. This flow control system differs from that of the first embodiment in that the differential pressure generating section 44 is integrated into a separate unit and is detachably attached to the flow control unit 40. And a manual closing valve 46 is inserted and connected downstream of the second pressure detecting means 45 in the flow path 2. Also, the proportional pressure reducing valve used for the proportional control valve 42 and the processing content of the electronic circuit 41 are partially modified.

The differential pressure generating section 44 includes a flow control unit 40
A base block composed of a manifold block or the like in which holes such as a bolt insertion hole for mounting on a hole and a drilled hole forming a part of the flow path 2 are formed, and a fixed throttle 44a capable of flowing a large flow rate.
And a variable restrictor 44b for flowing a small flow rate. The fixed restrictor 44a and the variable restrictor 44b are incorporated in the base block to be in a parallel connection state, and a differential pressure corresponding to the combined restrictor is applied to the flow path 2. Is to occur.

In the pressure reducing valve of the proportional control valve 42, in addition to an upstream port and a downstream port connected to the flow path 2, a return port connected to a tank or the like by an appropriate pipe is formed. When the control signal S is large, the pressure reducing valve variably controls the downstream pressure by flowing the pressure liquid from the upstream port to the downstream port while reducing the pressure so that the secondary pressure becomes the same. When the signal S is at or near zero, that is, at the control limit for decreasing the pressure on the downstream side, the return port and the downstream port are connected.

The electronic circuit 41 has the above set values A to
In addition to the limit pressure D, the limit pressure D is also input. When the pressure P1 exceeds the cutoff pressure C and further exceeds the limit pressure D, the control signal S is continuously forced to zero, and the flow rate Q and the pressure P1 and P2 are irreversibly lowered to the lower limit. Further, at the start of operation / operation, the pressure P
2 is controlled so that the flow rate Q becomes equal to the flow rate value A before the pressure value B reaches the pressure value B. When the pressure P2 temporarily exceeds the pressure value B and performs a steady operation, and the pressure P2 falls below the pressure value B, Control is performed to reduce the flow rate Q accordingly.

In this case, when the operation is started, the pumping speed is rapidly increased, and stable pumping is performed at a constant speed immediately after the start. At the end of the operation, the vehicle is decelerated in the same manner as described above, and safety is ensured. Further, the differential pressure generating section 4
4 is detachable from the flow control unit 40, before being mounted on the flow control unit 40, it is temporarily provided to an adjustment circuit, which is provided separately from the flow control unit 40 and is connected to an accurate flow meter or the like. Attached to the variable aperture 4
By adjusting 4b, an adjustment is made so as to generate a desired differential pressure when a predetermined flow rate is passed. This allows
In a simple manner, the characteristics of the differential pressure generating section 44 are made uniform in all the flow control units 40.

In a state where the closing valve 46 is completely closed,
By performing offset adjustment or the like of the control signal S, the pressure P1 also rises immediately when the control signal S becomes larger than zero, and when the control signal S becomes zero, the pressure P1 also reliably returns to zero or the tank pressure. Manual adjustment but easy. Alternatively, if the electronic circuit 41 is set to the automatic zero point adjustment mode with the closing valve 46 completely closed, the electronic circuit 4
1 increases or decreases the control signal S while monitoring the pressure P1, confirms that the pressure P1 has once become positive and then returns to zero or the tank pressure, and determines the control signal S based on the data collected at that time. The zero point / reference value is calculated, and the zero point / reference value is stored in a nonvolatile memory or the like. And
Thereafter, the control signal S is generated based on the reference. In this way, the zero adjustment can be completed very easily.

[0043]

Fifth Embodiment A specific configuration of a fifth embodiment of the flow control system according to the present invention will be described with reference to the drawings. 6A and 6B show the structure, wherein FIG. 6A is an overall circuit diagram of a hydraulic circuit and an electronic circuit, and FIG. 6B is a block diagram of the electronic circuit. This flow control system differs from that of the above-described fourth embodiment in that the electronic circuit 41 is embodied by a clock synchronous digital circuit, and that the pulse motor which varies the amount of aperture in the variable aperture 44b is used. And an electronic circuit 41 for generating an adjustment signal SS for controlling the operation of the pulse motor and the like.
Has been extended.

In this case, an operation circuit 51 for performing a function operation or the like
From the flow value A, the pressure value B, the shutoff pressure C, the pressure P1, and the pressure P2, a target flow rate Qa corresponding to the above-described pressure-flow rate characteristic (see FIG. 5B) is obtained, and a subtraction circuit and the like are included. The detected flow rate Qb is obtained from the pressures P1 and P2 by the arithmetic circuit 52, and the target flow rate Qa is calculated by the arithmetic circuit 53.
And the detected flow rate Qb, the control command value Sa is calculated. Usually, the control command value Sa is adopted as the control signal S by the selection circuit 55, and the same operation result as described above is obtained.

When the operation mode of the electronic circuit 41 is switched from the normal mode to the automatic differential pressure adjustment mode, the adjustment circuit 54 that is stopped in the normal mode operates. Then, in response to the selection switching signal Sc from the adjustment circuit 54, the selection circuit 55 adopts the control command value Sa from the adjustment circuit 54 as the control signal S, and in that state, the adjustment circuit 54 While changing the adjustment signal SS, the pressure P1,
In addition to inputting the data of P2, the flow rate-differential pressure characteristic in the differential pressure generating section 44 is also calculated based on the least square method so as to be closest to the desired characteristic. decide. When the adjustment amount Sd is stored in the non-volatile memory 56, the automatic differential pressure adjustment mode ends and the mode returns to the normal mode. Then, thereafter, at the time of system startup or other initialization, the adjustment amount Sd is read from the non-volatile memory 56 to generate an adjustment signal SS, thereby adjusting the variable throttle 44b and thus the differential pressure generating unit 44. You. In this way, the characteristic adjustment of the differential pressure generating section 44 is easily performed.

[0046]

[Others] In each of the above embodiments, the chemical pump and the hydraulic motor 3a connected to the chemical pump are used as the operating unit 3. However, the operating unit 3 is not limited to this. Various actuators may be appropriate.
In addition, the liquid is widely used because of its widespread use of hydraulic pressure.However, the liquid is not limited to hydraulic pressure.For example, water, a chemically synthesized liquid, and a mixed liquid of different kinds of liquids depend on the characteristics and restrictions of the application. Alternatively, a mixed liquid of powder and granules may be used.

Further, in the second embodiment, the control signal S
Is a digital signal, and in each of the other embodiments, the control signal S is an analog signal. However, the present invention is not limited to this, and any one may be adopted as the control signal S or the like. It is sufficient that the output circuit of the control signal S and the proportional control valve 42 receiving the control signal S are compatible with each other.
The settings of the values A, B, C, and D are not limited to the setting unit 41a. For example, the values may be input from a keyboard, may be downloaded from a host computer, and may be fixed values. If good, it may be written in a ROM or the like.

[0048]

As is apparent from the above description, in the flow control system according to the first solving means of the present invention, the flow characteristics can be arbitrarily set by the processing of the electronic circuit. Since the required pressure detecting means is also used to reflect the load state of the operating section, a flow control system that appropriately controls the flow rate according to the load state of the operating section can be easily realized. There is an advantageous effect that

In the flow control system according to the second solution of the present invention, the processing contents of the electronic circuit in the flow control system according to the first solution are embodied based on the characteristics of a chemical pump or the like. In addition, there is an advantageous effect that a flow control system suitable for hydraulic driving of a chemical pump or the like can be easily realized.

[Brief description of the drawings]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is for explaining the outline of a first embodiment of a flow control system of the present invention, in which (a) is a circuit diagram of a hydraulic circuit or the like showing an entire structure, and (b) is an operating characteristic. FIG. 4 is a pressure-flow characteristic diagram showing

FIGS. 2A and 2B are diagrams for explaining more specifically, FIG. 2A is a circuit diagram of a hydraulic circuit or an electronic circuit showing an entire structure, and FIG. 2B is a pressure-flow rate diagram showing operating characteristics. .

FIG. 3 is a circuit diagram of a hydraulic circuit and an electronic circuit showing an overall structure of a second embodiment of the flow control system of the present invention.

FIG. 4 is a circuit diagram of a hydraulic circuit and an electronic circuit showing an overall structure of a third embodiment of the flow control system of the present invention.

5A is a circuit diagram of a hydraulic circuit or an electronic circuit showing the entire structure of a fourth embodiment of the flow control system of the present invention, and FIG. 5B is a pressure-flow characteristic diagram showing operating characteristics. is there.

6A and 6B show the structure of a fifth embodiment of the flow control system of the present invention, wherein FIG. 6A is an overall circuit diagram of a hydraulic circuit and an electronic circuit, and FIG. 6B is a block diagram of the electronic circuit.

[Explanation of symbols]

1 Hydraulic pressure source (pump unit, pump + tank unit) 2 Flow path (piping, hose, joint, manifold block perforation) 3 Actuator (actuator) hydraulic motor 3a Hydraulic motor (actuator for driving chemical pump) 3b Chemical Pump (application requiring driving with specific pressure-flow rate characteristics) 3c Pumping liquid (liquid to be pumped out by chemical pump) 40 Flow control unit (hydraulic circuit + electronic circuit, flow control system) 41 Electronic circuit (arithmetic unit, control device) 41a Setter (operation means, input means, setting means) 41b Microprocessor (MPU) 41c A / D conversion circuit (feedback signal input means) 41d D / A conversion circuit (control signal output means) 42 Proportional control valve (electromagnetic Type, pulse drive type, pressure reducing valve, throttle valve, three-way valve) 43 1st pressure detecting means (pressure Gauge, pressure gauge) 44 Differential pressure generating section (throttle section) 44a Fixed throttle (main flow throttle) 44b Variable throttle (adjustment throttle) 45 Second pressure detecting means (pressure gauge, pressure gauge) 46 Closing valve (stop valve, Stop valve) 51, 52, 53 Operation circuit (function operation means) 54 Adjustment circuit (adjustment procedure control means) 55 Selection circuit (selector, switching unit) 56 Nonvolatile memory (adjustment amount holding means) A Flow rate value (constant value) ) B Pressure value (threshold) C Shutoff pressure D Limit pressure P1 pressure (first detection pressure) P2 pressure (second detection pressure) Q Flow rate S Control signal SS Adjustment signal

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroyuki Ishikawa 2-16-46 Minami Kamata, Ota-ku, Tokyo F-term in Tokimec Co., Ltd. (reference) 3H089 AA35 BB15 BB27 CC08 DA02 DA14 DB12 EE06 EE36 FF07 GG02 5H307 BB07 CC05 EE02 EE04 EE06 EE07 EE17 FF09 FF12 FF13 GG04 HH04 HH12 JJ03

Claims (7)

[Claims] 1. A proportional control valve, a first pressure detecting means, a differential pressure generating section, and a second pressure detecting means are sequentially provided in a flow path from a hydraulic pressure source to an operating section, and their detection is performed. A flow control system further comprising an electronic circuit for detecting a flow rate and controlling the proportional control valve based on a pressure, wherein the flow rate is determined according to a detected pressure of the second pressure detecting means. 2. The electronic circuit according to claim 1, wherein said electronic circuit controls said flow rate to be constant when the pressure detected by said second pressure detecting means exceeds a predetermined threshold value, and to reduce the flow rate when the detected pressure falls below the predetermined threshold value. The flow control system according to claim 1, wherein: 3. A proportional control valve interposed in a flow path from a hydraulic pressure source to an operating section, a differential pressure generating section interposed in the flow path at a downstream side of the proportional control valve; A first pressure detecting unit that measures a pressure in the flow path between the valve and the differential pressure generating unit and also outputs a signal of a first detected pressure, between the differential pressure generating unit and the operating unit; A second pressure detecting means for measuring the pressure in the flow path and also outputting a signal of the second detected pressure, and inputting the first detected pressure and the second detected pressure and, based on them, a flow rate in the flow path And generating a control signal for the proportional control valve based on the detected signal and sending the control signal to the proportional control valve.When the control signal is generated, the second detection pressure exceeds a predetermined threshold. When the flow rate becomes constant, the second detection pressure becomes equal to the threshold value. Around the flow control system comprising an electronic circuit for determining the content of the control signal so as to be reduced the flow rate accompanied to it. 4. The proportional control valve according to claim 1, wherein the proportional control valve is one of a proportional pressure reducing valve that variably controls a downstream pressure and a proportional throttle valve that variably controls an opening. Item 4. A flow control system according to any one of Items 3. 5. The control limit in which the proportional control valve has an upstream port, a downstream port, and a return port to a tank or the like to variably control the downstream pressure and decrease the downstream pressure. A proportional pressure reducing valve for communicating the return port with the downstream port, and an opening degree between the upstream port and the downstream port having an upstream port, a downstream port, and a return port to a tank or the like. And a proportional three-way valve for communicating the return port and the downstream port when the communication between the upstream port and the downstream port is cut off. The flow control system according to claim 1. 6. The flow control system according to claim 1, wherein said differential pressure generating section is a fixed throttle connected to a variable throttle. 7. The flow control system according to claim 6, wherein said differential pressure generating section is detachably mounted on said flow path.