JP2024125676A - Spool valve mechanism - Google Patents

Abstract

To provide a spool valve device capable of easily switching response characteristics.SOLUTION: A spool valve device 1 according to one embodiment comprises a spool valve 2 comprising a spool 21, an electric actuator 3 including a motor 5 and a linear motion mechanism 4 that converts rotational motion of the motor 5 into linear motion of the spool 21, and a control device 6 that controls the motor 5. The control device 6 stores a plurality of values as gains to be used in PI control for determining a current command to the motor 5 based on a position command for the motor 5, and switches the gain between the plurality of values.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a spool valve device including a spool valve.

Conventionally, there has been known a spool valve device in which a spool valve is driven by an electric actuator. The electric actuator includes a motor and a linear motion mechanism that converts the rotational motion of the motor into linear motion of the spool of the spool valve.

For example, Patent Document 1 discloses a spool valve device that includes a spool valve, an electric actuator, and a control device that controls the motor of the electric actuator. In Patent Document 1, the control device is called a "drive control unit."

JP 2019-49336 A

Generally, the control device for the spool valve device performs PI control, which determines the current command to the motor based on the position command for the motor. In PI control, multiple gains are used, and the response characteristics of the spool valve device are determined by these gains. For example, the response characteristics can be responsive, which moves the spool to the target position more quickly, or controllable, which moves the spool exactly to the target position.

However, because each gain is stored as a fixed value in the control device, it is not possible to use different spool valve devices depending on the application. Therefore, in order to prepare spool valve devices with different response characteristics, the same number of spool valve devices as the response characteristics are required. Alternatively, it is possible to switch the response characteristics with a single spool valve device by rewriting the control parameters stored as fixed values in the control device. However, this type of work is very difficult for end users.

Therefore, the present disclosure aims to provide a spool valve device that can easily switch response characteristics.

The present disclosure provides a spool valve device that includes a spool valve, a motor, an electric actuator including a linear motion mechanism that converts the rotational motion of the motor into linear motion of the spool, and a control device that controls the motor, the control device storing multiple values as gains to be used in PI control that determines a current command to the motor based on a position command for the motor, and switching the gain between the multiple values.

The present disclosure provides a spool valve device that can easily switch response characteristics.

1 is a schematic configuration diagram of a spool valve device according to a first embodiment. FIG. FIG. 2 is a block diagram of a control device for the spool valve device. 11 is a graph showing the change in the position of a spool over time. FIG. 6 is a schematic configuration diagram of a spool valve device according to a second embodiment. FIG. 2 is a block diagram of a control device for the spool valve device. FIG. 11 is a block diagram of a control device for a spool valve device according to a third embodiment.

First Embodiment
1 shows a spool valve device 1A according to a first embodiment. The spool valve device 1A includes a spool valve 2, an electric actuator 3 that drives the spool valve 2, and a control device 6.

The spool valve 2 is located between the hydraulic pump 11 and the hydraulic actuator 12 in the hydraulic circuit. In other words, hydraulic fluid is supplied from the hydraulic pump 11 to the hydraulic actuator 12 via the spool valve 2.

In this embodiment, the hydraulic actuator 12 is a double-acting cylinder and the spool valve 2 is a three-position valve. However, the hydraulic actuator 12 may also be a hydraulic motor. Alternatively, the hydraulic actuator 12 may be a single-acting cylinder and the spool valve 2 may be a two-position valve.

The spool valve 2 includes a housing 22 having a spool hole, and a spool 21 slidably inserted into the spool hole. A pump passage 23, a tank passage 24, and a pair of supply and discharge passages 25, 26 are formed in the housing 22. In the neutral position, the spool 21 blocks all of the pump passage 23, the tank passage 24, and the supply and discharge passages 25, 26, and when moved from the neutral position to one side or the other in the axial direction, it connects the pump passage 23 to one of the supply and discharge passages 25, 26 and connects the other of the supply and discharge passages 25, 26 to the tank passage 24.

The electric actuator 3 includes a motor 5 and a linear motion mechanism 4 that converts the rotational motion of the motor 5 into linear motion of the spool 21. The motor 5 is, for example, a servo motor. The linear motion mechanism 4 includes a threaded shaft connected to the output shaft of the motor 5, a nut that screws into the threaded shaft, a piston to which the nut is fixed and connected to the spool 21, and a holder that is attached to the housing 22 and holds the piston slidably in the axial direction of the spool 21. The motor 5 is attached to the housing 22 via the holder.

The motor 5 is provided with an angular position detector 7 that detects the angular position of the motor 5. The angular position detector 7 is, for example, a rotary encoder. The motor 5 is controlled by a control device 6.

With respect to the control device 6, the functions of the elements disclosed herein can be performed using circuits or processing circuits, including general purpose processors, special purpose processors, integrated circuits, Application Specific Integrated Circuits (ASICs), conventional circuits, and/or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuits. In this disclosure, a circuit, unit, or means is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. If the hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and/or the processor.

A position command for the motor 5 is input to the control device 6. Instead of inputting a position command for the motor 5 to the control device 6, a position command for the spool 21 may be input to the control device 6, and the control device 6 may convert the position command for the spool 21 into a position command for the motor 5.

The control device 6 is electrically connected to the angular position detector 7 described above. The control device 6 performs PI control to determine a current command to the motor 5 based on a position command for the motor 5. In this embodiment, as shown in FIG. 2, the PI control includes a position control loop to determine a speed command to the motor 5 based on the position command for the motor 5 and the position result, which is the detection result of the angular position detector 7, and a speed control loop to determine a current command to the motor 5 based on the speed command and the speed result obtained by differentiating the detection result of the angular position detector 7.

More specifically, in the position control loop, the control device 6 determines the speed command by adding a proportional term obtained by multiplying the deviation between the position command and the actual position by the P gain Kp to an integral term obtained by multiplying the integral of the proportional term by the I gain Ki. In the speed control loop, the control device 6 determines the current command by adding a proportional term obtained by multiplying the deviation between the speed command and the actual speed by the P gain Kvp to an integral term obtained by multiplying the integral of the proportional term by the I gain Kvi. However, the integral term of the position control loop may be the integral of the deviation between the position command and the actual position by the I gain Ki, and the integral term of the speed control loop may be the integral of the deviation between the speed command and the actual speed by the I gain Kvi.

In this embodiment, the control device 6 stores multiple values as the P gain Kp to be used in the position control loop. The control device 6 switches the P gain Kp between the multiple values. The number of multiple values may be two (large and small), three (large, medium and small), or four or more.

For example, the P gain Kp can be switched between a value α for emphasizing responsiveness, which moves the spool 21 to the target position more quickly, as shown by the solid line in FIG. 3, and a value β, which is smaller than the value α, for emphasizing controllability, which moves the spool 21 exactly to the target position, as shown by the dashed line in FIG. 3. When emphasizing responsiveness, overshooting is more likely to occur, and when emphasizing controllability, overshooting is less likely to occur.

In this embodiment, the control device 6 is also electrically connected to the input device 8. The input device 8 accepts the selection of one of multiple values stored in the control device 6 as the P gain Kp. For example, the input device 8 may be a changeover switch or a touch screen.

When a value for P gain Kp is selected on the input device 8, a switching flag corresponding to that value is input to the control device 6, and the control device 6 sets the P gain Kp to the value selected on the input device 8.

As described above, in this embodiment, multiple values are stored in the control device 6 as the P gain Kp used in the position control loop, so the response characteristics can be easily switched. Moreover, in this embodiment, the input device 8 is used, so the user can select the response characteristics.

<Modification>
The multiple values stored in the control device 6 as the P gain Kp may be determined not from the perspective of whether the spool 21 is moved to the target position sooner or exactly, but from the perspective of whether the flow rate of the hydraulic fluid passing through the spool valve 2 is made to reach the target flow rate sooner or exactly.

In the above embodiment, the control device 6 stores multiple values as the P gain Kp used in the position control loop and switches the P gain Kp between multiple values, but the control device 6 may store multiple values as the I gain Ki used in the position control loop and switch the I gain Ki between multiple values. Alternatively, the control device 6 may store multiple values as the P gain Kvp used in the speed control loop and switch the P gain Kvp between multiple values, or store multiple values as the I gain Kvi used in the speed control loop and switch the I gain Kvi between multiple values. Alternatively, the control device 6 may switch some or all of the P gain Kp and I gain Ki used in the position control loop and the P gain Kvp and I gain Kvi used in the speed control loop between multiple values.

The above modification can also be applied to the second and third embodiments described below.

Second Embodiment
4 shows a spool valve device 1B according to a second embodiment. In this embodiment and a third embodiment described later, the same components as those in the first embodiment are denoted by the same reference numerals, and duplicated explanations will be omitted.

In this embodiment, a detector 9, which is a pressure sensor that detects the pressure of the hydraulic fluid, is used instead of the input device 8 shown in FIG. 1. In the illustrated example, the detector 9 is provided in the pump line between the hydraulic pump 11 and the spool valve 2, but the detector 9 may be provided in one or both of the supply and discharge lines between the spool valve 2 and the hydraulic actuator 12.

As in the first embodiment, the control device 6 stores multiple values as the P gain Kp to be used in the position-velocity loop. However, in this embodiment, as shown in FIG. 5, the control device 6 switches the P gain Kp between the multiple values based on the detection value of the detector 9.

For example, as described in the first embodiment, when the control device 6 stores the responsiveness-oriented value α and the controllability-oriented value β, if the pressure detected by the detector 9 is smaller than a predetermined value, the work performed by the hydraulic actuator 12 is considered to be a secondary work, and the control device 6 sets the P gain Kp to the responsiveness-oriented value α. On the other hand, if the pressure detected by the detector 9 is larger than the predetermined value, the work performed by the hydraulic actuator 12 is considered to be a primary work, and the control device 6 sets the P gain Kp to the controllability-oriented value β.

For example, if the hydraulic actuator 12 raises and lowers the mold of a press device, the pressure detected by the detector 9 during the process of lowering the mold to the press position and the process of raising the mold will be smaller than a predetermined value, and the pressure detected by the detector 9 during the pressurizing process of further lowering the mold from the press position will be greater than the predetermined value.

In this embodiment, as in the first embodiment, multiple values are stored in the control device 6 as the P gain Kp used in the position control loop, so the response characteristics can be easily switched. Moreover, in this embodiment, the user does not need to select the response characteristics, while the P gain Kp can be appropriately switched depending on the operating state.

<Modification>
The detector 9 does not necessarily have to be a pressure sensor, and may be a flow meter that detects the flow rate of the hydraulic fluid. In this case, the flow meter may be provided in the pump line, or in one or both of the supply and discharge lines. When the detector 9 is a flow meter, if the flow rate detected by the detector 9 is greater than a predetermined value, it is considered that high-precision positioning control of the hydraulic actuator 12 is not necessary, and the control device 6 may set the P gain Kp to a value α that prioritizes responsiveness. On the other hand, if the flow rate detected by the detector 9 is less than the predetermined value, it is considered that high-precision positioning control of the hydraulic actuator 12 is necessary, and the control device 6 may set the P gain Kp to a value β that prioritizes controllability.

Alternatively, the detector 9 may detect the operating position of the hydraulic actuator 12. For example, if the hydraulic actuator 12 is a hydraulic cylinder, the detector 9 may be a stroke sensor, and if the hydraulic actuator 12 is a hydraulic motor, the detector 9 may be a rotary encoder.

Third Embodiment
A spool valve device 1C according to a third embodiment will be described with reference to Fig. 6. In this embodiment, similarly to the first embodiment, the control device 6 stores a plurality of values as the P gain Kp to be used in the position-speed loop.

In this embodiment, neither the input device 8 shown in FIG. 1 nor the detector 9 shown in FIG. 4 is used, and the control device 6 switches the P gain Kp between the multiple values based on a position command for the motor 5.

For example, as described in the first embodiment, when the control device 6 stores the responsiveness-oriented value α and the controllability-oriented value β, if the rate of change of the position command is smaller than a predetermined value, an overshoot is unlikely to occur, so the control device 6 may set the P gain Kp to the responsiveness-oriented value α. Conversely, if the rate of change of the position command is larger than the predetermined value, an overshoot is likely to occur, so the control device 6 may set the P gain Kp to the controllability-oriented value β.

In this embodiment, as in the first embodiment, multiple values are stored in the control device 6 as the P gain Kp used in the position control loop, so the response characteristics can be easily switched. Moreover, in this embodiment, the user does not need to select the response characteristics, while the P gain Kp can be appropriately switched in response to the position command.

<Other embodiments>
The present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present disclosure.

<Summary>
In a first aspect, the present disclosure provides a spool valve device comprising: a spool valve including a spool; an electric actuator including a motor and a linear motion mechanism that converts rotational motion of the motor into linear motion of the spool; and a control device that controls the motor, wherein the control device stores a plurality of values as gains to be used in PI control that determines a current command to the motor based on a position command for the motor, and switches the gain between the plurality of values.

With the above configuration, multiple values are stored as gains in the control device, making it easy to switch response characteristics.

In a second aspect, the spool valve device according to the first aspect may further include an input device that accepts a selection of one of the multiple values, and the control device may set the gain to the value selected by the input device. With this configuration, the user can select the response characteristics.

As a third aspect, in the first aspect, hydraulic fluid may be supplied from the hydraulic pump to the hydraulic actuator via the spool valve, and the control device may switch the gain between the multiple values based on the pressure or flow rate of the hydraulic fluid, or a detection value of a detector that detects the operating position of the hydraulic actuator. With this configuration, the user does not need to select a response characteristic, while the gain can be appropriately switched depending on the operating state.

As a fourth aspect, in the first aspect, the control device may switch the gain between the multiple values based on the position command. With this configuration, the user does not need to select a response characteristic, while the gain can be appropriately switched according to the position command.

As a fifth aspect, in any of the first to fourth aspects, the gain may be, for example, at least one of a P gain and an I gain used in a position control loop that determines a speed command based on a position command for the motor, and a P gain and an I gain used in a speed control loop that determines a current command for the motor based on the speed command.

Reference Signs List 1A, 1B, 1C Spool valve device 2 Spool valve 21 Spool 3 Electric actuator 4 Linear motion mechanism 5 Motor 6 Control device 8 Input device 9 Detector

Claims (5)

a spool valve including a spool;
an electric actuator including a motor and a linear motion mechanism that converts a rotational motion of the motor into a linear motion of the spool;
A control device for controlling the motor,
The control device stores a plurality of values as a gain used in PI control that determines a current command to the motor based on a position command for the motor, and switches the gain between the plurality of values. an input device for accepting a selection of one of the plurality of values;
2. The spool valve arrangement of claim 1, wherein said controller sets said gain to a value selected by said input device. Hydraulic fluid is supplied from the hydraulic pump to the hydraulic actuator via the spool valve;
2. The spool valve device according to claim 1, wherein the control device switches the gain between the plurality of values based on a detection value of a detector that detects a pressure or a flow rate of the hydraulic fluid, or an operating position of the hydraulic actuator. The spool valve device according to claim 1, wherein the control device switches the gain between the multiple values based on the position command. 5. The spool valve device according to claim 1, wherein the gain is at least one of a P gain and an I gain used in a position control loop that determines a speed command based on a position command for the motor, and a P gain and an I gain used in a speed control loop that determines a current command to the motor based on the speed command.

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