KR101143022B1 - Confluent control system - Google Patents

Abstract

Provided is a joining control system that can be smoothly shifted without shock when switching between single operation and joined operation. When the flow rate decreases below the necessity due to the cut-off characteristic, the operation of the second variable flow rate control device 2 is stopped to achieve energy saving. When the manipulated variable Vq from the pressure flow control unit 40 is equal to or less than the maximum speed Vmax1 of the first motor 12, the manipulated variable distribution unit 51 controls the first motor 12 through the first driver 13. ) Is driven by the first speed signal V1, while the manipulated variable Vq exceeds the maximum speed Vmax1 of the first motor 12, the first motor 12 is peaked through the first driver 13. While driving at the speed Vmax1, the second motor 22 is driven with the second speed signal V2 (V2 = Vq-Vmax1) through the second driver 23. As a result, it is possible to smooth the transition from the single operation to the combined operation so that no shock is generated.

Description

Confluence Control System {CONFLUENT CONTROL SYSTEM}

TECHNICAL FIELD This invention relates to the joining control system used for hydraulic systems, such as an injection molding machine and a press machine, for example.

Conventionally, as this kind of confluence control system, there is one shown in Fig. 5 (see Japanese Patent Laid-Open No. 4-78306).

This confluence control system connects the electromagnetic proportional valve 110 to the discharge line 103 of the variable displacement pump 101, and discharge line 103a of the fixed displacement pump 104 to the discharge line 103. Are joining. The check valve 105 is provided in this discharge line 103a, and the unload valve 106 is connected. The unload valve 106 is controlled by the output from the comparator 111.

On the other hand, the inclined plate drive cylinder 108 for driving the inclined plate of the variable displacement pump 101 is controlled by the inclined plate control valve 109.

When the flow rate command value qref input to the comparator 111 is smaller than a predetermined value, the unload valve 106 is turned off to the position N1, and the oil discharged by the fixed displacement pump 104 is Returning to the tank 102, only the oil discharged by the variable displacement pump 101 is sent to the actuator. At this time, the electromagnetic proportional valve 110 is opened according to the flow command value qref, and the inclined plate control valve 109 operates so that the differential pressure before and after the electromagnetic proportional valve 110 becomes constant, thereby driving the inclined plate. The discharge amount of the variable displacement pump 101 is controlled via the cylinder 108.

On the other hand, when the flow rate command value qref becomes large and the discharge amount of the variable displacement pump 101 reaches the maximum flow rate which is the limit value, the unload valve 106 is turned on by a signal from the comparator 111. It becomes the position N2. Thereby, between the fixed displacement pump 104 and the tank 102 is cut off, and the oil discharged by the fixed displacement pump 104 is sent to the discharge line 103 through the check valve 105, and the variable displacement pump The pump 101 merges with the oil discharged.

By controlling the unload valve 106 in this manner, as shown in FIG. 6, the discharge flow rate of the oil continuously up to the total capacity of the capacity of the variable displacement pump 101 and the capacity of the fixed displacement pump 104 ( q) can be controlled.

However, in the conventional merging control system, after the discharge amount of the variable displacement pump 101 reaches the limit, the oil from the variable displacement pump 101 and the oil from the fixed displacement pump 104 merge. Therefore, as shown in FIG. 6, the flow rate of oil rapidly increases immediately after confluence. That is, from the supply state of oil by only the variable displacement pump 101 to the transition region 50 shifting to the supply state of oil by both the variable displacement pump 101 and the fixed displacement pump 104. In this case, the flow rate and pressure of the oil are rapidly increased and shock is generated. Such a problem may occur even when the oil is supplied by both the variable displacement pump 101 and the fixed displacement pump 104 from the oil supply state to the oil supply state by the variable displacement pump 101 alone. .

Accordingly, an object of the present invention is to provide a confluence control system that can smoothly shift without shock when switching between single operation and confluence operation, in a confluence control system for condensing liquids discharged from a plurality of pumps. Is in.

In order to solve the above problems, the joining control system of the present invention,

A first variable flow control device capable of discharging the liquid to the first discharge line by controlling the flow rate;

A second variable flow control device capable of discharging the liquid by controlling the flow rate to the second discharge line joining the first discharge line;

A check valve installed in the second discharge line such that the flow from the second variable flow control device to the first discharge line is in a forward direction;

A pressure sensor for detecting a pressure of the first discharge line;

A pressure flow controller which receives one pressure command, one flow command, and a signal indicating the detected pressure from the pressure sensor, and outputs an operation amount for obtaining the pressure and the flow rate according to the pressure command and the flow rate command;

When the operation amount is received from the pressure flow control unit, and the operation amount is equal to or less than a predetermined set value, the first variable flow control device discharges a liquid whose flow rate continuously changes in accordance with the operation amount, and the second variable flow rate. In order to prevent the control device from discharging the liquid, first and second speed signals are generated based on the operation amount and output to the first and second variable flow rate control devices, respectively, while the operation amount exceeds the set value. In this case, the first and second variable flow rate control devices generate the first and second speed signals based on the manipulated amount so as to discharge the liquid so that the total flow rate continuously changes in accordance with the manipulated amount. A manipulated-variable distribution part which outputs each to a 2nd variable flow control apparatus is provided, It is characterized by the above-mentioned.

According to the said structure, the said pressure flow control part receives the signal which shows one pressure command, one flow rate command, and the detected pressure from the said pressure sensor, and the operation amount for obtaining the pressure and flow volume according to the said pressure command and a flow rate command. Is output to the manipulated variable distributor.

The said manipulated variable distribution part discharges the liquid of the flow volume which changes continuously according to the said manipulated quantity, when the said manipulated variable is below a predetermined set value, and the said 2nd variable flow control apparatus is liquid. The first and second speed signals are generated on the basis of the operation amount and output to the first and second variable flow rate control devices, respectively, so as not to discharge the liquid crystal, while the operation amount exceeds the set value. The first and second variable flow rate control devices generate the first and second speed signals based on the manipulated amount so that the first and second variable flow rate control devices discharge the liquid whose total flow rate continuously changes in accordance with the manipulated amount. Output each to the device.

As described above, according to the present invention, the discharge flow rate from the first variable flow rate control device and the discharge flow rate from the second variable flow rate control device are joined together, and the first and second speeds created by distributing the manipulated value in the manipulated variable distribution unit. Since the first and second variable flow rate control devices are controlled by the signal, no shock occurs at the time of switching between the single operation and the combined operation, so that the transition between the single operation and the combined operation can be smoothed.

Further, according to the present invention, since the operation amount distribution unit is provided at the rear end of the pressure flow control unit, the operation of the second variable flow control device is stopped when the pressure flow control unit is in a state where the flow rate is reduced to be less than or equal to a predetermined set value. Therefore, energy saving can be achieved.

In one embodiment,

When the manipulated variable is less than or equal to the set value, the manipulated variable distribution unit outputs the manipulated variable as a first speed signal to the first variable flow control device, and outputs a second speed signal that is zero to the second variable flow control device. When the manipulated value exceeds the set value, the set value is outputted to the first variable flow rate control device as a first speed signal, and the value obtained by subtracting the set value from the manipulated value. Is output as the second speed signal to the second variable flow control device.

According to the said embodiment, when the said operation amount is below the said setting value, it is set as the 1st speed signal, the 2nd speed signal is set to 0, and when the said operation amount exceeds the said setting value, the setting value Since the value obtained by subtracting the set value from the manipulated variable is the second speed signal, the first and second speed signals can be generated by a simple calculation.

In one embodiment,

The said 1st and 2nd variable flow control apparatus is comprised with the fixed displacement pump and the servomotor which drives the fixed displacement pump.

According to the said embodiment, since the said 1st and 2nd variable flow control apparatus is comprised from the fixed displacement pump and the servomotor which drives the fixed displacement pump, the structure is simple and inexpensive.

In one embodiment,

The pressure flow control section limits the value calculated by the pressure control calculation based on the pressure command and the signal indicating the detected pressure from the pressure sensor so as not to exceed the value according to the flow rate command.

According to the said embodiment, since the value calculated by the said pressure control calculation does not exceed the value according to the said flow volume command, flow rate control is automatically performed when a pressure is lower than a target value by simple calculation.

One embodiment,

A control signal indicating a stop when the control signal indicating the start or stop of the first variable flow control device is received and a signal indicating the operation amount is received from the pressure flow control unit, and the operation amount is equal to or less than a threshold value smaller than the set value. A control signal distribution unit for outputting a signal to the second variable flow control device and outputting a control signal indicating driving to the second variable flow control device when the operation amount exceeds the threshold.

According to the said embodiment, since the said control signal distribution part outputs the control signal which shows stop of control to a 2nd variable flow control apparatus, when the said operation amount is below the threshold value smaller than the said set value, power consumption will be reduced. While the energy saving can be achieved by reducing the amount, the control signal indicating the start of control is output to the second variable flow control device when the operation amount exceeds the threshold value, so that the second variable flow rate is entered. Responsiveness is good at startup of the control device, and no shock occurs.

According to one embodiment,

The pressure flow control unit,

Based on the pressure command, the flow rate command, and a signal indicating the amount of operation from the pressure flow rate control unit, the cutoff characteristic of the pressure override in the pressure flow rate characteristic diagram is set, and the pressure command to which the cutoff characteristic is given is output. And a cutoff characteristic setting unit.

According to the said embodiment, since the said pressure flow volume control part contains the cut-off characteristic setting part which outputs the pressure command to which the cut-off characteristic was provided, it is possible to improve the stability of a system by adjusting a cut-off width freely.

According to one embodiment,

The cutoff characteristic setting unit calculates the pressure command to which the cutoff characteristic is given by the following equations (1) and (2).

Where Pi_C is the pressure command given the cutoff characteristic,

Vq is an operation amount output from the pressure flow control unit,

Pi is the pressure command,

Qi is the flow rate command,

CF is a predetermined constant and represents the cutoff width.

According to the said embodiment, since cutoff characteristic is provided by the said Formula (1), the cutoff characteristic can be provided by simple calculation.

According to the present invention, the discharge flow rate from the first variable flow rate control device and the discharge flow rate from the second variable flow rate control device are joined together, and the first and second speed signals are generated by distributing the manipulated value in the manipulated variable distribution unit. Since the first and second variable flow control devices are continuously controlled, the transition between the single operation and the combined operation can be performed smoothly without generating shock.

Further, according to the present invention, since the operation amount distribution unit is provided at the rear end of the pressure flow control unit, the operation of the second variable flow control device is stopped when the pressure flow control unit is in a state where the flow rate is reduced to be less than or equal to a predetermined set value. Therefore, energy saving can be achieved.

1 is a block diagram of a confluence control system of one embodiment of the present invention;
2 is a diagram showing a flow rate characteristic between a flow rate command and a flow rate.
3 shows pressure flow rate characteristics between pressure and flow rate.
4 is an enlarged view of FIG. 3.
5 is a hydraulic circuit diagram of a conventional joining control system.
6 is a graph showing a relationship between a flow rate command value and a discharge flow rate of a conventional confluence control system.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment which shows this invention is demonstrated in detail.

As shown in FIG. 1, the confluence control system includes a first variable flow control device 1, a second variable flow control device 2, a pressure flow control unit 40, and a signal distribution unit 50. Equipped with.

The first variable flow control device 1 includes a first fixed displacement pump 11, a first motor 12 that drives the first fixed displacement pump 11, and the first motor 12. And a encoder 14 for detecting the rotational angle of the first motor 12, and controlling the rotational speed of the first motor 12, as an example of liquid. The hydraulic fluid is discharged by controlling the flow rate from the first fixed displacement pump 11. The first motor 12, the first driver 13, and the encoder 14 constitute an example of a servo motor.

In addition, the second variable flow control device 2 includes a second fixed displacement pump 21, a second motor 22 for driving the second fixed displacement pump 21, and the second motor. A second driver 23 for driving the 22 and an encoder 24 for detecting a rotation angle of the second motor 22 are provided to control the rotation speed of the second motor 22, thereby operating oil. The flow rate is controlled and discharged from the second fixed displacement pump 21. The second motor 22, the second driver 23, and the encoder 24 constitute an example of a servo motor.

Thus, in this embodiment, the 1st and 2nd fixed displacement pumps 11 and 21 are used for the 1st and 2nd variable flow control apparatuses 1 and 2, without using a variable displacement pump. Therefore, the structure is simplified.

On the other hand, the 1st fixed displacement type pump 11 of the said 1st variable flow control apparatus 1 discharges hydraulic oil to the 1st discharge line 10, and supplies it to the main machine hydraulic circuit 5. The pressure of the hydraulic oil of the first discharge line 10 is detected by the pressure sensor 7. In addition, the second fixed displacement pump 21 of the second variable flow control device 2 discharges the hydraulic oil to the second discharge line 20 joined to the first discharge line 10. The second discharge line 20 has a check valve 6 in which the flow from the second fixed displacement pump 21 of the second variable flow control device 2 to the first discharge line 10 becomes a forward direction. It is provided so that the hydraulic oil does not flow back from the first discharge line 10 to the second discharge line 20.

On the other hand, the pressure flow control unit 40 receives a signal indicating a pressure command Pi, one flow command Qi, and a detected pressure from the pressure sensor 7, and receives the pressure command Pi. ) And the operation amount Vq for obtaining the pressure and the flow rate according to the flow rate command Qi are calculated and output to the signal distribution unit 50.

Specifically, the pressure flow control unit 40 includes a cutoff characteristic setting unit 41, an addition point 42, a pressure control calculating unit 43, and a speed limiter 45.

The cutoff characteristic setting unit 41 receives the pressure command Pi, the flow rate command Qi, and the operation amount Vq, and the detected pressure (load pressure) detected by the pressure sensor 7 is determined. If the maximum command pressure (highest target pressure) exceeds 90%, for example, as shown in Figs. 3 and 4, the pressure command (cut-off control such that the flow rate command Qi is substantially cut off is performed. Based on Pi, the flow rate command Qi, and the operation amount Vq, the pressure command Pi_C given the cutoff characteristic is calculated and output to the addition point 42.

The pressure command Pi_C to which this cutoff characteristic was given is computed by following formula (1) and (2).

&Quot; (1) "

<Equation 2>

Where Pi_C is the pressure command given the cutoff characteristic,

Vq is the operation amount output from the pressure flow control unit 40,

Pi is the pressure command,

Qi is the flow rate command,

CF is a predetermined constant and represents the cutoff width.

In this manner, the pressure command Pi_C to which the cutoff characteristic is given can be obtained by a simple calculation according to Equations 1 and 2 described above.

3 and 4, the cutoff width (difference between the target pressure and the pressure for starting the cutoff control) CF is set to 10% of the maximum target pressure. The cutoff width CF is generally set to 5 to 10% of the highest target pressure, but if it is smaller than that, the control is likely to be unstable.

In the above Equation 1, Vq < 0 in Vq &lt; 0 means that in the pressure holding state (in the main machine hydraulic circuit 5, the hydraulic cylinder (not shown) is pressed toward the load at a high pressure, but it is not moving. Not in the state], when the pressure command Pi is issued to lower the pressure of the first discharge line 10, the first motor 12 is rotated in reverse to correspond to a state in which the load pressure is lowered.

In addition, in FIG.3 and FIG.4, both a pressure axis and a flow axis are represented by% with respect to the highest value, a broken line shows the flow volume of the 1st fixed displacement pump 11, and a dashed-dotted line shows the 2nd fixed capacity. The flow rate of the type | mold pump 21 is shown, and the solid line has shown the total flow volume of the 1st and 2nd fixed displacement pumps 11 and 21. FIG. 4 is an enlarged view of a main part of FIG. 3.

The method for imparting the cutoff characteristic is not limited to the above-described Equations 1 and 2, and various known methods are possible. For example, unlike the said cutoff characteristic setting part 41, based on the flow volume command, the pressure command, and the detection value from a pressure sensor, the operation amount as which control along the solid line of FIG. 3 and FIG. 4 is performed is obtained. A calculation formula may be used or a storage device that stores a look-up table that draws solid lines in FIGS. 3 and 4 may be used. Alternatively, the cutoff characteristic setting section itself may be omitted, and the cutoff characteristic may be provided by characteristics such as a relief valve.

On the other hand, the addition point 42 outputs the signal obtained by subtracting the detection signal from the pressure sensor 7 from the pressure command Pi_C given the cutoff characteristic to the pressure control calculation unit 43.

The said pressure control calculating part 43 receives the signal from the addition point 42, for example, performs PID (proportional integral derivative) control calculation, and outputs the obtained pressure signal Vp to the speed limiter 45, for example. . However, the pressure control calculation unit 43 may perform other known pressure control calculations such as PI (proportional integral) control calculation.

The speed limiter 45 restricts the pressure signal Vp from the pressure control calculating section 43 so as not to exceed the value according to the flow rate command Qi, and outputs the operation amount Vq.

In this way, since the operation amount Vq is obtained by restricting the pressure signal Vp from the pressure control calculating section 43 so as not to exceed the value according to the flow rate command Qi, the pressure is a target value by a simple calculation. If it is lower than the flow rate, the flow rate is automatically controlled.

On the other hand, the signal distributor 50 includes a manipulated variable distributor 51 and a control signal distributor 52. The manipulated variable distributor 51 distributes the manipulated variable Vq into a first speed signal V1 and a second speed signal V2 on the basis of a rule to be described later. The first speed signal V1 and the second speed signal V2 are distributed. The speed signal V2 is output to the first driver 13 of the first variable flow control device 1 and the second driver 23 of the second variable flow control device 2, respectively. Moreover, the said control signal distribution part 52 receives the control signal S1 and the operation amount Vq, produces | generates the control signal S2 by the rule which is later described, and it is the 1st variable flow control apparatus 2 of the 2nd variable flow control apparatus 2; 2 is distributed to the driver 23, that is, output.

When the operation amount Vq is equal to or less than a predetermined set value, for example, the maximum speed Vmax1 of the first motor 12, the operation amount distribution unit 51 sets the operation amount Vq as the first speed signal. Outputs the second speed signal V2, which is 0, to the first driver 13 of the first variable flow control device 1 as V1, and the second driver of the second variable flow control device 2 ( 23 and outputs the set value Vmax1 as the first speed signal V1 when the manipulated value Vq exceeds the set value Vmax1. While outputting to the first driver 13, the second variable flow control device (Vq-Vmax1) obtained by subtracting the set value Vmax1 from the manipulated variable Vq as the second speed signal V2 ( Output to the 2nd driver 23 of 2).

More specifically, the manipulated variable distributor 51 generates the first and second speed signals V1 and V2 with the following speed distribution algorithm.

Where Vq is the manipulated variable,

Vmax1 is the maximum speed of the first motor 12 of the first variable flow control device 1,

V1 is the first speed signal,

V2 is the second speed signal.

In this manner, the manipulated variable distributor 51 is configured to generate a first speed signal when the manipulated variable Vq is equal to or less than the maximum speed Vmax1 of the first motor 12, that is, when the flow rate command is 40% or less in FIG. 2. Let V1 be the manipulation amount Vq and the second speed signal V2 be 0, and only the first motor 12 will be the first speed signal V1 (V1 = Vq) and the first driver 13. Is driven through, and the second motor 22 is stopped with the second speed signal V2 (V2 = 0) to achieve energy saving.

In Fig. 2, both the flow rate command and the flow rate are expressed in% of the highest value, the broken line indicates the flow rate of the first fixed displacement pump 11, and the dashed line indicates the flow rate of the second fixed displacement pump 21. The flow rate is shown, and the solid line indicates the total flow rate of the first and second fixed displacement pumps 11 and 21.

On the other hand, the manipulated variable distributor 51 has a first speed when the manipulated variable Vq exceeds the maximum speed Vmax1 of the first motor 12, that is, when the flow rate command exceeds 40% in FIG. With the signal V1 at the maximum speed Vmax1, the first motor 12 is driven at the maximum speed Vmax1 through the first driver 13, and the second motor 22 is driven by the second driver ( It drives with the 2nd speed signal V2 (V2 = Vq-Vmax1) via 23.

In this way, when the manipulated variable Vq is equal to or less than the maximum speed Vmax1 of the first motor 12, the manipulated variable distributor 51 removes only the first motor 12 through the first driver 13. While driving with one speed signal V1, while the operation amount Vq exceeds the maximum speed Vmax1 of the first motor 12, the first motor 12 is driven through the first driver 13 to the maximum speed Vmax1. Drive the second motor 22 with the second speed signal V2 (V2 = Vq-Vmax1) through the second driver 23, and thus the first fixed displacement pump 11 As shown in Fig. 2, the transition from the single operation in which the hydraulic oil is discharged only from the first and the second fixed displacement pumps 11 and 21 to the conjoining operation in which the hydraulic oil is joined is smooth and shock is generated. You can do it.

Further, as described above, the manipulated variable distributor 51 can obtain the first and second speed signals V1 and V2 by a simple calculation.

In addition, the said control signal distribution part 52 is the agent which shows ON or OFF that makes the 1st driver 13 of the 1st variable flow control apparatus 1 into a starting state or a stop state. 1 control signal S1 and the signal which shows the operation amount Vq from the pressure flow control part 40 are received. Here, the first control signal S1 being off does not mean that the speed of the first motor 12 is controlled to zero, but the control itself of the first motor 12 is stopped. And when the 1st control signal S1 is off, the said control signal distribution part 52 will give the 2nd control signal S2 of the off state which shows a stop state, and the 2nd of the 2nd variable flow control apparatus 2 Output to the driver 23. Further, the control signal distribution unit 52 is configured to have a predetermined threshold value smaller than the set value Vmax1 when the operation amount Vq received from the pressure flow controller 40 is on when the first control signal S1 is on. Vmax1) / 2] or less, outputs the second control signal S2 that is turned off to the second driver 23 of the second variable flow control device 2, while the operation amount Vq is equal to the threshold value [(Vmax1). / 2], the 2nd control signal S2 of the ON which shows a starting state is output to the 2nd driver 23 of the 2nd variable flow control apparatus 2. As shown in FIG. The threshold value [(Vmax1) / 2] is a value corresponding to 1/2 of the maximum speed Vmax1 of the first motor 12 corresponding to the set value.

In more detail, the said control signal distribution part 52 produces | generates the 2nd control signal S2 with the following control signal distribution algorithm, and the 2nd driver 23 of the 2nd variable flow control apparatus 2 is carried out. Will output

Where Vq is the manipulated variable,

Vmax1 is the maximum speed of the first motor 12 of the first variable flow control device 1.

In this way, the control signal distribution unit 52 turns off the second control signal S2 when the operation amount Vq is 1/2 or less of the maximum speed Vmax1 of the first motor 12, Energy saving can be achieved by turning off the second driver 23 of the second variable flow control device 2 so as not to consume power.

In the second variable flow control device 2, the second driver 23 receives the second speed signal V2 (V2) until the manipulated variable Vq exceeds the maximum speed Vmax1 of the first motor 12. Since the hydraulic fluid is not discharged without rotating the second fixed displacement pump 21 because it is 0), the operating amount Vq is essentially until the maximum speed Vmax1 of the first motor 12 is exceeded. The second control signal S2 may be off. However, in this embodiment, the said control signal distribution part 52 supplies a 2nd control signal S2, when the said operation amount Vq exceeds 1/2 of the maximum speed Vmax1 of the 1st motor 12. FIG. Since it turns on and enters the standby state by turning on the 2nd driver 23 of the 2nd variable flow control apparatus 2, as soon as the operation amount Vq exceeds the maximum speed Vmax1 of the 1st motor 12, The second driver 23 may operate by receiving the second speed signal V2 (V2 = Vq-Vmax1) to drive the second motor 22 in a responsive manner. Therefore, the 1st fixed displacement pump 11 of the 1st variable flow control apparatus 1 from the single operation which discharges hydraulic fluid only from the 1st fixed displacement pump 11 of the 1st variable flow control apparatus 1. ) And the second variable flow rate control device 2 can be quickly shifted to the confluence operation in which the hydraulic fluid from the second fixed displacement pump 21 is joined, and smoothly without steps as shown in FIG. 2. .

In the confluence control system having the above configuration, when one pressure command Pi and one flow command Qi are input to the pressure flow rate control unit 40, the cutoff characteristic setting unit 41 is configured to perform the pressure. Based on the command Pi, the flow rate command Qi, and the operation amount Vq, the pressure command Pi_C given the cutoff characteristic is calculated by the following equations (1) and (2).

&Quot; (1) &quot;

<Equation 2>

When the detected pressure (load pressure) detected by the pressure sensor 7 exceeds the value of (Pi-CF) by the pressure command Pi_C, as shown in FIG. 3 and FIG. 4, the flow rate command Qi. The cutoff control is performed as if the cutoff was substantially cut off.

The pressure command Pi_C is input to the addition point 42 from the cutoff characteristic setting section 41. At this addition point 42, the detection signal from the pressure sensor 7 is subtracted from the said pressure command Pi_C, and the obtained signal is input into the pressure control calculation part 43 from the addition point 42. FIG.

The pressure control calculation unit 43 receives a signal from the addition point 42, performs PID (proportional integral differential) control, and the obtained pressure signal Vp is input to the speed limiter 45.

In the speed limiter 45, a limit is applied to the pressure signal Vp from the pressure control calculating section 43 so as not to exceed the value according to the flow rate command Qi, so as to obtain an operation amount Vq. ) Is output to the signal distribution unit 50.

The operation amount distribution unit 51 of the signal distribution unit 50 is the first speed distribution algorithm based on the operation amount Vq and the maximum speed Vmax1 of the first motor 12 as a set value. And second speed signals V1 and V2.

In this manner, the manipulated variable distributor 51 is configured to generate a first speed signal when the manipulated variable Vq is equal to or less than the maximum speed Vmax1 of the first motor 12, that is, when the flow rate command is 40% or less in FIG. 2. Let V1 be the manipulation amount Vq and the second speed signal V2 be 0, and only the first motor 12 will be the first speed signal V1 (V1 = Vq) and the first driver 13. Drive through, and the second motor 22 is stopped by the second speed signal V2 (V2 = 0), thereby achieving energy saving.

Further, the manipulated variable distribution unit 51 has a first speed when the manipulated variable Vq exceeds the maximum speed Vmax1 of the first motor 12, that is, when the flow rate command exceeds 40% in FIG. 2. With the signal V1 at the maximum speed Vmax1, the first motor 12 is driven at the maximum speed Vmax1 through the first driver 13, and the second motor 22 is driven by the second driver ( It drives with the 2nd speed signal V2 (V2 = Vq-Vmax1) via 23.

In this way, when the manipulated variable Vq is equal to or less than the maximum speed Vmax1 of the first motor 12, the manipulated variable distributor 51 removes only the first motor 12 through the first driver 13. While driving with one speed signal V1, while the operation amount Vq exceeds the maximum speed Vmax1 of the first motor 12, the first motor 12 is driven through the first driver 13 to the maximum speed Vmax1. Drive the second motor 22 with the second speed signal V2 (V2 = Vq-Vmax1) through the second driver 23, and thus the first fixed displacement pump 11 As shown in Fig. 2, the transition from the single operation in which the hydraulic oil is discharged only from the first and the second fixed displacement pumps 11 and 21 to the conjoining operation in which the hydraulic oil is joined is smooth and shock is generated. You can do it.

Moreover, in this confluence control system, the operation amount distribution part 51 is provided in the rear end of the pressure flow control part 40, the operation amount Vq from the said pressure flow control part 40 is distributed, and the 1st speed signal V1 is carried out. ), Since the second speed signal V2 is created and input to the first and second drivers 13 and 23, as can be seen from FIG. 4, which is an enlarged view of the main part of FIG. 3, in the cutoff characteristic, When the pressure exceeds the value of (Pi-CF), the rotation speed of the second motor 22 gradually decreases, the discharge flow rate of the second fixed displacement pump 21 gradually decreases from 60%, and the pressure is 96% And the discharge flow rate becomes zero. On the other hand, the first motor 12 rotates at a constant rotational speed until the pressure reaches 96%, and the discharge flow rate of the first fixed displacement pump 11 is constant at 40%, but if the pressure exceeds 96% The rotational speed of the first motor 12 gradually decreases, the discharge flow rate of the first fixed displacement pump 11 gradually decreases from 40%, the pressure is 100%, and the discharge flow rate becomes zero.

In this way, the manipulated variable distribution unit 51 provided at the rear end of the pressure flow control unit 40 distributes the manipulated variable Vq from the pressure flow control unit 40 so that the first speed signal V1 and the second speed signal ( Since V2) is made, the operation of the second fixed displacement pump 21 stops when the flow rate is reduced to a high pressure of 96% or more due to the cutoff characteristic, that is, the second fixed displacement pump ( Since the discharge amount of 21) is set at 0 in the range of 96 to 100%, energy saving can be achieved.

If, for example, the flow rate command Qi is distributed at the front end of the pressure flow control part 40, the pressure is transferred immediately to 100% of both the first fixed displacement pump 11 and the second fixed displacement pump 21. It will run until then, and energy saving will not be achieved.

In addition, the said control signal distribution part 52 produces | generates the 2nd control signal S2 with the following control signal distribution algorithm, and outputs it to the 2nd driver 23 of the 2nd variable flow control apparatus 2. .

Where Vq is the manipulated variable,

Vmax1 is the maximum speed of the first motor 12 of the first variable flow control device 1.

Thus, when the said control amount Vq is 1/2 or less of the maximum speed Vmax1 of the 1st motor 12, the said control signal distribution part 52 turns off the 2nd control signal S2, Energy saving is achieved by turning off the second driver 23 of the second variable flow control device 2 so as not to consume power.

The control signal distribution unit 52 turns on the second control signal S2 when the operation amount Vq exceeds 1/2 of the maximum speed Vmax1 of the first motor 12. Since the second driver 23 of the second variable flow control device 2 is turned on to enter the standby state, the second driver (as soon as the operation amount Vq exceeds the maximum speed Vmax1 of the first motor 12). 23 may operate by receiving the second speed signal V2 (V2 = Vq-Vmax1) to drive the second motor 22 in a responsive manner. Therefore, the 1st fixed displacement pump 11 of the 1st variable flow control apparatus 1 from the single operation which discharges hydraulic fluid only from the 1st fixed displacement pump 11 of the 1st variable flow control apparatus 1. ) And the second variable flow rate control device 2 can be quickly shifted to the confluence operation in which the hydraulic fluid from the second fixed displacement pump 21 is joined, and smoothly without steps as shown in FIG. 2. .

In the said embodiment, although the 1st variable flow control apparatus 1 and the 2nd variable flow control apparatus 2 were used, these 3rd variable flow control apparatus, the 4th variable flow control apparatus, etc. are further used, Discharge hydraulic oils, such as a 3 variable flow control apparatus and a 4th variable flow control apparatus, may respectively join the 1st discharge line 10 via a check valve.

Moreover, in the said embodiment, the manipulated-variable distribution part 51 is based on the manipulated variable Vq and the maximum speed Vmax1 of the 1st motor 12 as a predetermined setting value,

Although the 1st and 2nd speed signals V1 and V2 were produced | generated by the speed distribution algorithm, the said setting value may be set to a value slightly smaller than the maximum rotational speed Vmax1 of the said 1st motor 12. As shown in FIG.

The speed distribution algorithm of the manipulated variable distributor is not limited to the example described above. In short, when the manipulated variable is less than or equal to a predetermined set value, the first variable flow rate controller 1 continuously changes the flow rate according to the manipulated amount. The first and second speed signals are generated based on the operation amount so that the second variable flow rate control device 2 does not discharge the liquid while discharging the changing liquid, and the operation amount changes the set value. When exceeding, the first and second variable flow rate control devices 1 and 2 generate the first and second speed signals based on the operation amount so as to discharge the liquid so that the total flow rate is changed continuously according to the operation amount. It is not limited to the above-mentioned example as long as it is created, and the characteristic may be represented by the broken line, a curve, etc. which have many bending points.

In the above embodiment, the ratio of the maximum rotational speed Vmax1 of the first motor 12 and the maximum rotational speed Vmax2 of the second motor 22 is 4: 6, and the first fixed displacement pump 11 Since the discharge capacity (Vcc) of the second fixed displacement pump 21 is the same, the switching between single operation and confluence operation is performed by the flow rate command of 40% divided by Vmax1 × Vcc: Vmax2 × Vcc = 4: 6. In part. However, each of the maximum rotational speeds Vmax1 and Vmax2 of the first and second motors 12 and 22 or the respective discharge capacities Vcc1 and Vcc2 of the first and second fixed displacement pumps 11 and 21 It can be any value. In that case, switching between single operation and confluence operation is performed at the portion of the flow rate command divided by the ratio of Vmax1 × Vcc1: Vmax2 × Vcc2.

In addition, the pressure flow control part 40 and the signal distribution part 50 of the said embodiment may be comprised by software, a digital circuit, or may be comprised by an analog circuit.

Moreover, in the said embodiment, although the 1st and 2nd fixed displacement pumps 11 and 21 were used, it is also possible to control discharge amount by using one as a variable displacement pump.

It is also possible to use an inverter as a driver.

As the pressure sensor, a current sensor that detects the drive current of the first motor 12 and indirectly detects the pressure of the first discharge line 10 may be used.

In addition, in the said embodiment, although the liquid was hydraulic fluid, it is not limited to hydraulic fluid, Any liquid can be used, and this invention is applicable to all hydraulic systems.

Claims (7)

A first variable flow rate control device 1 capable of discharging the liquid by controlling the flow rate on the first discharge line 10,
A second variable flow rate control device 2 capable of discharging the liquid by controlling the flow rate to the second discharge line 20 joined to the first discharge line 10;
A check valve (6) provided in the second discharge line (20) such that the flow from the second variable flow control device (2) to the first discharge line (10) is in a forward direction;
A pressure sensor 7 detecting a pressure of the first discharge line 10,
Receiving a signal indicating a pressure command Pi, a flow rate command Qi, and a detected pressure from the pressure sensor 7, the pressure and flow rate according to the pressure command Pi and the flow rate command Qi are received. A pressure flow controller 40 for outputting an operation amount Vq for obtaining
When the operation amount Vq is received from the pressure flow rate control unit 40 and the operation amount Vq is equal to or less than a predetermined set value, the first variable flow rate control device 1 continuously changes the flow rate according to the operation amount Vq. While discharging the liquid to be discharged, the first and second speed signals V1 and V2 are generated based on the operation amount Vq so that the second variable flow control device 2 does not discharge the liquid. And output to the second variable flow control devices 1 and 2, respectively, and when the manipulated variable Vq exceeds the set value, the first and second variable flow control devices 1 and 2 total flow rate. The first and second variable flow rate control devices (1) and the second speed signal (V1 and V2) are created based on the manipulated value (Vq) to discharge the liquid so as to continuously change in accordance with the manipulated value (Vq). And a manipulated variable distributor 51 for outputting to 1 and 2), respectively. Control systems that join. 2. The first variable flow rate control device (1) according to claim 1, wherein the manipulated variable distribution unit (51) uses the manipulated variable (Vq) as the first speed signal (V1) when the manipulated variable (Vq) is equal to or less than the set value. Output the second speed signal V2 to the second variable flow control device 2, and when the manipulated value Vq exceeds the set value, the set value is While outputting to the said 1st variable flow control apparatus 1 as a 1st speed signal V1, the value obtained by subtracting the said set value from the said operation amount Vq is obtained as said 2nd speed signal V2. The confluence control system, which outputs to the variable flow control apparatus (2). The servo motor according to claim 1 or 2, wherein the first and second variable flow control devices (1 and 2) drive a fixed displacement pump (11 and 21) and its fixed displacement pump (11 and 21). Joining control system, characterized in that consisting of a motor. The said flow volume flow control part 40 is a value calculated by the pressure control calculation based on the pressure command Pi and the signal which shows the detected pressure from the said pressure sensor 7, The said flow volume flow control part 40 has the said flow volume A joining control system, characterized in that the limit is not exceeded according to the command Qi. The method according to claim 1, wherein the control amount indicating the start or stop of the first variable flow rate control device 1 is received, and a signal indicating the operation amount Vq is received from the pressure flow rate control part 40, and the operation amount ( When Vq) is less than or equal to the threshold value smaller than the set value, a control signal indicating stop is output to the second variable flow control device 2, while when the manipulated variable Vq exceeds the threshold value, driving is performed. And a control signal distributor (52) for outputting the control signal to the second variable flow control device (2). The method of claim 1, wherein the pressure flow control unit 40,
Based on the pressure command Pi, the flow rate command Qi, and a signal indicating the operation amount Vq from the pressure flow rate control unit 40, the cutoff characteristic of the pressure override in the pressure flow rate characteristic diagram is set; And a cutoff characteristic setting section (41) for outputting a pressure command to which the cutoff characteristic has been applied. 7. The joining control system according to claim 6, wherein the cutoff characteristic setting section (41) calculates a pressure command to which the cutoff characteristic is given by the following equations (1) and (2).
<Equation 1>

&Quot; (2) &quot;

Where Pi_C is the pressure command given the cutoff characteristic,
Vq is the operation amount output from the pressure flow control unit 40,
Pi is the pressure command,
Qi is the flow rate command,
CF is a predetermined constant and represents the cutoff width.

Images