JP2567378B2 - Drive cylinder servo controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo control device for controlling the relative movement speed of a piston in a drive cylinder such as a hydraulic cylinder, and more particularly to a drive cylinder. The present invention relates to a control device that brakes and positions relative movement of pistons.

(Prior Art) Methods for controlling a hydraulic cylinder by a flow control valve include, for example, a meter-in method and a meter-out method.

The meter-in system is a system in which the operating speed is controlled by reducing the flow rate in the conduit on the inlet side to the hydraulic cylinder. In this meter-in system, the pipe on the outlet side of the cylinder is generally open to atmospheric pressure, so when the moving direction of the piston in the cylinder and the acting direction of the load are the same, the piston is self-propelled. There is a problem that there is a risk of

The meter-out method is a method of controlling the operating speed by reducing the flow rate in the conduit on the outlet side of the hydraulic cylinder.
In this meter-out system, the back pressure resulting from the throttling of the flow rate acts on the piston in the hydraulic cylinder, so that the piston does not run by itself even if a load acts in the moving direction of the piston.

(Problem to be Solved by the Invention) However, in the conventional method, when the piston is to be stopped at an arbitrary position, if the deceleration is rapidly performed, the flow control valve is rapidly throttled when stopped. As a result, surge pressure is generated, and vibration due to the generation of surge pressure is likely to occur. Further, if the deceleration is performed gently, it takes a long time to stop the piston.

Therefore, the deceleration effect may be increased and a mechanical braking force may be applied to the piston rod in the hydraulic cylinder, but there is a problem that the structure becomes complicated and the positioning control is affected.

(Means for Solving the Problems) In view of the conventional problems as described above, the present invention provides a first and second pressure chambers in the drive cylinder by a piston that is relatively movably installed in the drive cylinder. A first valve is provided between the pressure source and each of the first and second circuits connected to the first and second pressure chambers, the first valve being capable of disconnecting and connecting each of the circuits and the pressure source. The first and second circuits are provided with first and second flow rate control valves which are capable of restricting the flow rate under the control of the control device.
In the bypass circuit to which the circuit of FIG. 3 is connected, a second valve that can freely connect and disconnect the bypass circuit is provided and a third flow control valve that can control the flow rate under the control of the control device is arranged. It will be.

(Operation) In the above configuration, the first and second drive cylinders
Since the first and second flow control valves controlled by the control device are respectively arranged in the first and second circuits connected to the pressure chambers of the first pressure chamber, for example, from the first circuit to the first pressure chamber. When the working fluid is supplied to the piston and the piston in the drive cylinder is moved relatively, the throttle of the second flow control valve arranged in the second circuit is controlled to be discharged from the second chamber of the drive cylinder. By controlling the flow rate of the working fluid, the relative moving speed of the piston can be controlled.

Since the third flow rate control valve is arranged in the bypass circuit that can freely connect and disconnect the first and second circuits, the working fluid is supplied to the first chamber of the drive cylinder as described above,
When the working fluid in the chamber is throttle-controlled by the second flow rate control valve and the relative movement of the piston is controlled, the bypass circuit is connected and the first flow rate control valve is connected via the third flow rate control valve. When a part of the working fluid is introduced from the circuit side to the second circuit side, the relative moving speed of the piston becomes lower.

The pressure in the first chamber of the drive cylinder is slightly larger than the pressure corresponding to the sum of the load due to the pressure in the second chamber due to the restriction of the second flow control valve and the load acting on the piston. Therefore, the piston is relatively moved by the pressure in the first chamber.

Here, the throttle of the second flow control valve is kept constant and the third
When the throttle of the flow control valve is opened gradually,
Since the flow rate of the working fluid flowing into the circuit side gradually increases, the pressure in the second chamber of the drive cylinder 1 also gradually increases.

When the pressure in the second chamber gradually increases as described above, the pressure in the first chamber also gradually increases, but the pressure in the first chamber does not increase more than the pressure applied by the pressure source. When the pressure corresponding to the load due to the pressure and the sum of the loads and the pressure in the first chamber become equal, the piston stops moving.

That is, for example, while controlling the second flow rate control valve to control the movement of the piston of the drive cylinder, by connecting a bypass circuit and appropriately controlling the third flow rate control valve, the piston can be controlled to an arbitrary value. It is something that can be stopped in position.

When the piston is stopped by controlling the third flow rate control valve as described above, a part of the working fluid on the first circuit side is introduced to the second circuit side even when the piston is stopped rapidly. Then, the pressure on the second chamber side is increased, and the piston is not stopped by abruptly reducing the second flow rate control valve. Therefore, surge pressure or the like caused by suddenly reducing the circuit There is no generation and no vibration due to the surge pressure is generated.

(Embodiment) Referring to FIG. 1, a piston 3 is slidably fitted in the drive cylinder 1, and the piston 3 causes a first pressure chamber 5 and a second pressure in the drive cylinder 1. It is divided into a room 7 and a room 7. The piston 3 has a drive cylinder 1
A piston rod 3R protruding outwardly from the piston rod 3R is integrally attached, and a tip end portion of the piston rod 3R is appropriately connected to an appropriate operating portion such as an industrial machine or a machine tool. The actuating section is actuated by the drive cylinder 1, and acts on the drive cylinder 1 as a load PL.

First and second pressure chambers 5, 7 in the drive cylinder 1
Are connected to ports 9 and 11, respectively.
, And the first solenoid valve 15 connected to the pressure source 13 at the 4-port 3-position are connected via the first and second circuits 17 and 19, respectively. The first solenoid valve 15
Energizes the first solenoid SOL1, P port and B
The port is connected and the A port and the T port are connected. When the second solenoid SOL2 is excited, the P port and the A port are connected and the B port and the T port are connected. Then, the first and second solenoids SOL1 and SOL2
When both are non-excited, they are in the neutral position, and the first and second circuits 17 and 19 are locked.

The first and second circuits 17 and 19 are connected to check valves 21 and 23, respectively, which allow the working fluid from the pressure source 13 to flow into the drive cylinder 1 but prevent the backflow, respectively.
Flow control valves 25 and 27 are connected in parallel to the check valves 21 and 23, respectively. Each of the flow rate control valves 25 and 27 is configured so that the opening of the throttle can be adjusted according to the magnitude of the voltage or current applied to the solenoids SOL25 and SOL27 provided therein. Therefore, the flow rate control valves 25 and 27 can appropriately control the opening degree of the throttle by appropriately controlling the voltage or current applied to the solenoids SOL25 and SOL27.

The first circuit 17 and the second circuit 19 include a bypass circuit 29.
The bypass circuit 29 is connected to the second solenoid valve 31 that can freely connect and disconnect the bypass circuit 29.
Is provided. This second solenoid valve 31 becomes a communication state by exciting the solenoid SOL31,
The bypass circuit 29 is normally cut off.

A check valve 33 that allows the flow of the working fluid from the first circuit 17 side is connected between the second solenoid valve 31 and the first circuit 17, and the check valve 33 includes:
A flow rate control valve 35 similar to the flow rate control valves 25 and 27 described above is connected in parallel. Further, a check valve 37 that allows the flow of the working fluid from the second circuit 19 side is connected between the second solenoid valve 31 and the second circuit 19, and the check valve 37 is connected to the check valve 37. Has a flow control valve 39 connected in parallel.

In the above configuration, for example, the first solenoid valve
When the first solenoid SOL1 in 15 is excited, the pressure source
13 and the first circuit 17 are connected, and the second circuit 19 and the tank are connected. Therefore, the working fluid of the pressure source 13 passes through the first circuit 17 and the check valve 21 to drive the drive cylinder 1.
Will be supplied to the first pressure chamber 5 side. Further, the working fluid in the second pressure chamber 7 in the drive cylinder 1 flows out to the tank via the second circuit 19, the flow control valve 27 and the first solenoid valve 15.

Therefore, the piston 3 in the drive cylinder 1 is
It will be understood that it moves to the left in the figure, and its moving speed can be appropriately controlled by adjusting the throttle of the flow control valve 27.

As described above, when the piston 3 moves to the left in FIG. 1 and reaches the predetermined position, when the solenoid SOL31 in the second renoid valve 31 is excited, the first circuit 17 and the second circuit 19 are generated. Will be in communication. Therefore, a part of the working fluid in the first circuit 17 is
Drive cylinder 1 via 29, flow control valve 39, and second circuit 19
The second pressure chamber 7 acts on the second pressure chamber 7.

Here, when the throttle of the second flow control valve 27 is kept constant and the throttle of the flow control valve 39 is gradually opened, the first circuit 17
Side to the second circuit 19 side, the flow rate of the working fluid gradually increases, and the pressure in the second pressure chamber 7 gradually increases.

As described above, when the pressure in the second pressure chamber 7 gradually increases, the pressure in the first pressure chamber 5 also gradually increases, but since it does not increase beyond the pressure applied from the pressure source 13, When the sum of the pressure in the second pressure chamber 7 and the load of the piston 3 and the pressure in the first pressure chamber 5 are balanced, the movement of the piston 3 is stopped.

As described above, when the piston 3 is stopped, the piston 3 can be stopped at an arbitrary position by appropriately controlling the throttles of the flow rate control valves 27, 39. Even when the control action for stopping the piston 3 is performed relatively rapidly, the flow control valve 27 is not suddenly throttled, and the first circuit 17 side to the second circuit 19
Since a part of the working fluid flows through the second pressure chamber 7 of the drive cylinder 1 through the above action, the surge pressure can be prevented from being generated. After the piston 3 is stopped, the first solenoid valve 15 is switched to the neutral position and the second solenoid valve 31 is switched to the cutoff state, so that the drive cylinder 1 is held in the locked state.

The control device for controlling the moving speed and the positioning of the piston 3 in the drive cylinder 1 can be configured as shown in FIG. 2, for example.

First, an appropriate position detector 41 is provided to detect the moving positions of the piston 3 and the piston rod 3R in the drive cylinder 1. As the position detector 41, for example, a linear scale such as a Magnescale can be used,
The present embodiment exemplifies a rotary detector that includes a roller that is rotated in contact with the piston rod 3R and that outputs a pulse when the roller rotates.

The output pulse of the position detector 41 is input to the position calculation unit 43 and the speed calculation unit 45. The position calculator 43 counts the pulses input from the position detector 41 to detect the moving positions of the piston 3 and the piston rod 3R. The speed calculation unit 45 uses the pulse input from the position detector 41 and the clock pulse input from the clock pulse transmitter 47 to determine the piston 3 and the piston rod.
It calculates the moving speed of 3R.

The position data output from the position calculator 43 is the first
Are input to the comparison unit 49 and the second comparison unit 51 of. The first comparison unit 49 compares the position data of the deceleration start position and the stop position input from the position data upper setting unit 53 of the current position input from the position calculation unit 43, and the both position data match. At this time, the solenoid SOL31 of the second solenoid valve 31 acts to excite or demagnetize.

The second comparison unit 51 includes the position data of the current position input from the position calculation unit 43, the current speed data input from the speed calculation unit 45, and the position data input from the setting unit 53.
Compare stroke speed data and deceleration speed data,
It serves to output speed data such as stroke speed and deceleration speed to the valve control units 55 and 57 in order to control the speed to a preset speed corresponding to the moving position of the piston 3 and the piston rod 3R.

The valve control units 55 and 57 correspond to the speed data such as the stroke speed and the deceleration speed input from the second comparing unit 51, and the solenoids SOL27 and SOL39 of the flow control valves 27 and 39, respectively.
To control the throttles of the flow rate control valves 27 and 39.

It should be noted that, as is clear, the setting unit 53 includes the piston 3 and the piston rod which are previously input from the appropriate setting input unit.
The function of storing data such as deceleration start position, stop position, stroke speed and deceleration speed of 3R and the like and outputting them to the comparison units 49 and 51 is provided.

With the above configuration, when the drive cylinder 1 is operated and the piston 3 and the piston rod 3R move as described above, the position detector 41 outputs a pulse in conjunction with the movement of the piston rod 3R. Based on the output pulse of the position detector 41, the position calculator 43 detects the moving positions of the piston 3 and the piston rod 3R, and the speed calculator 45 detects the moving speed. Piston 3 and piston rod 3R
When the preset deceleration start position is reached, the first comparison unit
The control signal is output from 49, and the second solenoid valve 31
The solenoid SOL31 is excited, and as described above, the first
The circuit 17 and the second circuit 19 are connected.

As described above, the piston 3 and the piston rod 3R reach the deceleration start position and the solenoid valve 31 is switched to the communicating state, and at the same time, the control signal is output from the second comparison unit 51 to the valve control units 55 and 57. It Each valve controller 55, 57
In the above, each throttle is appropriately controlled via each solenoid SOL27, SOL39 in each flow control valve 27, 39 corresponding to the control signal.

As described above, by appropriately controlling the throttles of the flow rate control valves 27, 39, after the piston 3 and the piston rod 3R are positioned at the preset stop positions, the solenoids are appropriately commanded by the control unit. By demagnetizing the solenoids of the valves 15 and 31, the drive cylinder 1 is held in the locked state.

It should be noted that the piston 3 and the piston rod 3R can be controlled by the same configuration when moving to the right in FIG.

Further, the present invention is not limited to the above-described embodiments, but can be implemented in other modes by making appropriate changes.

(Effects of the Invention) As will be understood from the above description of the embodiments, the present invention is, in short, the first and the first inside of the drive cylinder 1 by the piston 3 which is relatively movably installed inside the drive cylinder 1. Each of the circuits 17 is provided between the pressure source 13 and the first and second circuits 17, 19 connected to the first and second pressure chambers 5, 7 by dividing the pressure chambers 5, 7. , 19 and the pressure source 13 are provided by arranging a first valve 15 which can freely disconnect and connect the first and second valves.
First and second flow rate control valves 25 and 27, which can control the flow rate under the control of the control device, are provided in the circuits 17 and 19 of FIG.
Bypass circuit 29 connecting the first and second circuits 17 and 19
And a second valve that can freely disconnect the bypass circuit 29.
31 is arranged and provided, and a third flow control valve whose flow rate can be controlled to be throttled is arranged under the control of the control device.

As is apparent from the above configuration, in the present invention, the first and second circuits 17 and 19 connected to the first and second pressure chambers 5 and 7 of the drive cylinder 1 are controlled by the respective control devices. Since the first and second flow rate control valves 25 and 27 are respectively arranged, for example, the working fluid is supplied from the first circuit 17 to the first pressure chamber 5 so that the piston 3 in the drive cylinder 1 is opposed to each other. When the moving cylinder 1 moves, the throttle of the second flow control valve 27 arranged in the second circuit 19 is controlled to drive the drive cylinder 1
The relative moving speed of the piston 3 can be controlled by controlling the flow rate of the working fluid discharged from the second chamber 7.

In the present invention, the first and second circuits 17, 19
Since the third flow rate control valve is arranged in the bypass circuit 29 which can be connected and disconnected, the working fluid is supplied to the first chamber 5 of the drive cylinder 1 and the working fluid in the second chamber 7 is supplied to the first chamber 5 as described above. When the relative movement of the piston 3 is controlled by the throttle control by the second flow control valve 27, the bypass circuit 29 is connected, and the first circuit is connected via the third flow control valve.
When a part of the working fluid is introduced from the 17 side to the second circuit 19 side,
The relative moving speed of the piston 3 becomes slower.

The pressure in the first chamber 5 in the drive cylinder 1 corresponds to the sum of the load due to the pressure in the second chamber 7 due to the restriction of the second flow control valve 27 and the load PL acting on the piston 3. Since the pressure is slightly higher than the pressure applied to the piston 3, the piston 3 is relatively moved by the pressure in the first chamber 5.

Here, if the throttle of the second flow rate control valve 27 is held constant and the throttle of the third flow rate control valve is gradually opened, the flow rate of the working fluid flowing from the first circuit 17 side to the second circuit 19 side gradually. Since the pressure increases, the pressure in the second chamber 7 of the drive cylinder 1 also gradually increases.

When the pressure in the second chamber 7 gradually increases as described above,
Although the pressure in the first chamber 5 also gradually increases, the pressure in the first chamber 5 does not increase more than the pressure applied by the pressure source 13, so the load due to the pressure in the second chamber 7 and the load When the pressure corresponding to the total load of PL and the pressure in the first chamber 5 become equal, the piston 3 stops moving.

That is, according to the present invention, for example, when the second flow control valve 27 is controlled to control the movement of the piston 3 of the drive cylinder 1, the bypass circuit 29 is connected to appropriately control the third flow control valve. By doing so, the piston 3 can be stopped at an arbitrary position.

As described above, the piston 3 is controlled by controlling the third flow control valve.
When stopping the piston 3, even if the piston 3 is stopped rapidly, a part of the working fluid on the side of the first circuit 17 is transferred to the second circuit.
The configuration is such that it is introduced to the 19 side to increase the pressure on the second chamber 7 side, and the piston 3 is not stopped by suddenly reducing the second flow rate control valve 27, so the circuit is sharply reduced. There is no generation of surge pressure or the like due to the above, and no vibration due to the generation of the surge pressure.

[Brief description of drawings]

The drawings show one embodiment of the present invention, and FIG. 1 is an explanatory diagram of a hydraulic circuit embodying the present invention. FIG. 2 is a block diagram of an example of a control circuit. 1 …… Cylinder, 3 …… Piston 5,7 …… Pressure chamber, 17,19 …… Circuit 29 …… Bypass circuit 25,27,35,37 …… Flow control valve

Claims (1)

(57) [Claims] 1. A drive cylinder (1) is divided into first and second pressure chambers (5, 7) by a piston (3) which is relatively movably installed inside the drive cylinder (1). Provided, the first and second pressure chambers (5, 7) connected to the first,
A first valve (15) is arranged between the second circuit (17, 19) and the pressure source (13) so that the circuit (17, 19) and the pressure source (13) can be disconnected. The first and second circuits (17, 19) are provided with the first and second flow rate control valves (25, 27) which can control the flow rate under the control of the controller. The bypass circuit (29), to which the first and second circuits (17, 19) are connected, is provided with a second valve (31) capable of disconnecting the bypass circuit (29). A servo control device for a drive cylinder, characterized in that a third flow control valve for controlling the flow rate is arranged under the control of (3).