JPH03244804A - Reciprocating type driving device - Google Patents

Abstract

PURPOSE:To reduce shock in the reversal of a fluid cylinder by carrying out pressure feedback so that each pressing force on the head side and rod side of the fluid cylinder is balanced, and generating the pressure damping effect. CONSTITUTION:The outlet pressure of a three-port servovalve 5 is detected by a pressure sensor 31, and the pressure difference between the above-described signal and the signal 30 for making the pressing force for a piston equal is calculated in a calculation circuit 33. The pressure difference signal 35, signal of the position detector 7 of a hydraulic cylinder 3, signal passing through a differentiation circuit 12, and a position instruction signal 16 are inputted into a servo controller 40, and used for the output control of the three-port servovalve 5. Accordingly, the pressure feedback for constant speed movement is carried out for the feedback control for position and speed, and the shock due to the reversal of the hydraulic cylinder 3 is reduced, and the stick slip in the low speed operation can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a reciprocating drive device for driving a heavy object or the like.

<Prior Art> Conventionally, there are the following types of reciprocating drive devices of this type. As shown in FIG.
A differential circuit 6 is formed by connecting a port servo valve 5 and connecting the 3-port servo valve 5 and the pressure source 1 to the rod side port 3b of the hydraulic cylinder 3. and,
A position signal I from a position detector 7 that detects the position of the heavy object 2, that is, the position of the piston rod 3c of the hydraulic cylinder 3.
I, a signal created by differentiating this position signal II with a differentiating circuit 12, and a position command signal 16 are input to the servo controller 15 to create a control signal 18, which is input to the 3-port servo valve 5. There is.

FIG. 4 is a block diagram of the reciprocating drive device.

The subtraction circuits 21 and 23 and the voltage/current conversion circuit 25 in FIG. 4 constitute a part of the servo controller 15. The position of the piston rod 3c of the hydraulic cylinder 3 is detected by a position detector 7, and the position signal from the position detector 7 is input to a subtraction circuit 2J to create a position deviation signal 22 representing the deviation from the position command signal 16. be done. Then, the difference between this position error signal 22 and the speed signal created by differentiating the position signal 11 from the position detector 7 with the differentiation circuit 12 is calculated in the subtraction circuit 23, and the control signal 24 representing this difference is / current is input to the 3-port servo valve 55 via the current converter 25, and foot bank control of the position and speed of the hydraulic cylinder 3 is performed.

<Problems to be Solved by the Invention> By the way, in the reciprocating drive device shown in Fig. 3.4, the position and speed of the hydraulic cylinder 3 are controlled by a position and speed feedback loop, but the differential circuit 6, the speed of the hydraulic cylinder 3 is high, and the heavy object 2 is being driven, so if the 3-port servo valve 5 is switched to reverse the operating direction of the cylinder 3, an extremely large shock will occur. There's a problem. That is,
While maintaining high loop gain for position control and speed control,
Moreover, it is not possible to reduce fluctuations in the fluid pressure of the head side port 3a. As a result, the heavy object 2 undergoes rapid acceleration and deceleration movements, which increases the shock upon reversal.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to perform pressure feedback in a reciprocating drive device having a fluid cylinder driven by a differential circuit so as to balance the pressing force due to the fluid force between the head side and the rod side against the piston of the fluid cylinder. By creating a pressure damping effect, the shock when the fluid cylinder is reversed is reduced.
The purpose is to enable smooth reversal.

Means for Solving the Problems> In order to achieve the above object, the present invention connects a 3-port servo valve between the head side port of a fluid cylinder and a pressure source, and connects the 3-port servo valve to the pressure source and the 3-port servo valve. and the rod side port of the fluid cylinder to form a differential circuit, and detect the deviation between the position signal from the position detector that detects the position of the piston rod of the fluid cylinder and the position command signal. In the reciprocating drive device that controls the 3-port servo valve using a position deviation signal from a subtraction circuit for position deviation to be calculated, a pressure sensor detects fluid pressure at a head side port of the fluid cylinder, and a pressure sensor for detecting the fluid pressure at the head side port of the fluid cylinder; For pressure deviation, which calculates the pressure deviation between the signal representing the fluid pressure on the head side and the output signal from the pressure casenosa, which equalizes the pressing force from the head side against the piston with the pressing force due to the fluid from the rod side. The difference between the pressure deviation signal output from the pressure deviation subtraction circuit and the position deviation signal output from the position deviation subtraction circuit is calculated, and a signal representing this deviation is sent to the three ports. A subtraction circuit is provided to output an output to the servo valve, and pressure feedback is performed so that the pressing force on the piston due to the fluid pressure on the piston rod side of the fluid cylinder and the pressing force on the piston due to the fluid pressure on the head side are equal. It is characterized by what it did.

<Operation> The position of the piston rod of the fluid cylinder is detected by a position detector, and the position signal from this position detector is input to a subtraction circuit for position deviation, and in this subtraction circuit for position deviation, the position command signal and position are The positional deviation is calculated from the signal, and the positional deviation signal is output. On the other hand, the pressure at the head side port of the fluid cylinder is detected by a pressure sensor, and the pressure signal from this pressure case sensor is input to a subtraction circuit for pressure deviation. This subtraction circuit for pressure deviation includes:
A signal representing the fluid pressure on the head side that equalizes the pressing force of the fluid against the piston from the head side with the pressing force of the fluid against the piston of the fluid frinzo from the rod side, and the signal from the pressure sensor are input, A pressure deviation signal is output. The pressure deviation signal is used to restore the original balance when the pressing force of the fluid against the piston from the piston rod side of the fluid frinzo and the pressing force of the fluid against the piston from the head side are out of balance. be. The output signal from the subtraction circuit for position deviation and the signal from the subtraction circuit for pressure deviation are further subtracted by another subtraction circuit, and a control signal is output from this subtraction circuit to the three-port servo valve.

Therefore, the 3-port servo valve controls the fluid frinzo according to the position command signal, and makes sure that the pressing force of the fluid frinzo on the piston due to the fluid pressure on the piston rod side is equal to the pressing force on the piston due to the fluid pressure on the head side. As a result, the position of the fluid and heavy objects can be controlled without any sudden acceleration or deceleration. Looking at it from another perspective, this pressure feedback applies pressure braking to the fluid cylinder. Therefore, even if the operating direction of the fluid cylinder is switched, the switching can be performed smoothly, and noise can be reduced. Furthermore, since pressure braking is applied in this manner, stick-slip of the fluid cylinder at low speeds can be prevented.

<Example> Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

In FIG. 1, ■ is a pressure source, 2 is a heavy workpiece, 3 is a hydraulic cylinder as an example of a fluid cylinder, 5 is a 3-port servo valve, 6 is a differential circuit, 7 is a position detector, 1
Reference numeral 2 denotes a differential circuit, which has exactly the same configuration as the conventional example shown in FIG.

Further, 31 is a pressure sensor for detecting the fluid pressure of the head side port 3a of the hydraulic flip 3, and 33 is the head side port 3a for equalizing the pressing force of the fluid pressure on the head side and the rod side against the piston 3d of the hydraulic flip 3. A pressure deviation subtraction circuit 40 is a servo controller that calculates the deviation between a signal representing the fluid pressure of the pressure sensor 31 and a pressure signal from the pressure case sensor 31.

FIG. 2 is a block diagram showing the reciprocating drive device shown in FIG. 1. Subtraction circuits 2+, 23 . shown in FIG.
37 and the voltage/current conversion circuit 25 constitute the servo controller 40.

According to the above configuration, the piston rod 3 of the hydraulic cylinder 2
The position of c is detected by a position detector 7, and a position signal 11 from this position detector 7 is input to a subtraction circuit 21. This subtraction circuit 21 is a subtraction circuit that outputs a position command signal 16 and a position signal 11.
A position deviation signal 22 is created and output from the above. The above position signal 11 is input manually to a differentiating circuit 12, and this differentiating circuit 12 outputs a signal 39 representing the speed. A difference between the signal 39 representing the speed from the differentiation circuit 12 and the position error signal 22 is created by the subtraction circuit 23, and a signal 42 representing this deviation is input to the subtraction circuit 37. On the other hand, the pressure at the head side port 3a of the hydraulic flip 3 is detected by a pressure sensor 31, and a signal 32 from this pressure sensor 3I is input to a subtraction circuit 33 for pressure deviation. In addition, a hydraulic flip 3 is included in the subtraction circuit 33 for pressure deviation.
A signal 30 is input such that the pressing force due to the fluid pressure from the head side and the pressing force due to the fluid pressure from the piston rod 3c side on the piston 3d are equal. This signal 30 is expressed by the following equation, where Ah is the pressure receiving area on the head side of the piston 3d of the hydraulic flip, and Ar is the hydraulic area on the piston rod 3c side of the piston 3d.

((Ar)/(Ah))
This is a signal that attempts to restore balance when the pressing force exerted by the fluid acting on it is out of balance. Looking at it from a different perspective, this is a signal that always causes the piston 3h to move at a constant velocity. The deviation between this pressure deviation signal 35 and the signal 42 from the subtraction circuit 23 is calculated by the subtraction circuit 37, and a signal 44 representing this deviation is inputted to the 3-port surf valve 5 via the voltage/current conversion circuit 25, and the signal 42 is inputted to the hydraulic cylinder. 3 is controlled.

In this way, in addition to position and speed feedback, this reciprocating drive device performs pressure feedback so that the hydraulic cylinder 3 moves at a constant velocity to obtain a pressure damping effect, so that the hydraulic cylinder 3 that drives a heavy object can Even if the operating direction of No. 3 is reversed, slippage can be reduced, and stick-slip can also be prevented at low speeds.

In the embodiments described above, velocity foot banking may also be performed, velocity feedback may be removed, or acceleration feedback may be added.

The point is to control the fluid cylinder driven by the differential circuit by position feedback, and at the same time to perform pressure feedback to obtain a pressure damper effect on the fluid cylinder.

<Effects of the Invention> As is clear from the above, the reciprocating drive device of the present invention has the following effects:
A fluid cylinder driven by a differential circuit having a 3-port surf valve is controlled by position feedback, and a subtraction circuit is used to control the fluid cylinder from sudden acceleration motion based on the pressure signal of the head side port detected by a pressure sensor. Since pressure feedback is performed to prevent this, even if the fluid cylinder is operated at high speed by the differential circuit, it will operate smoothly without sudden acceleration or deceleration, and it will also reduce the pressure damping effect. As a result, even if the operating direction of the fluid cylinder is reversed, yoke can be reduced, and stick-slip can be eliminated at low speeds.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a reciprocating drive device according to an embodiment of the present invention;
FIG. 2 is a block diagram of the above embodiment, FIG. 3 is a circuit diagram of a conventional reciprocating drive device, and FIG. 4 is a block diagram of a conventional reciprocating drive device. ■...Pressure source, 2...Heavy object, 3...Hydraulic cylinder,
5-3 port servo valve, 6... Differential circuit, 31 ・Pressure horn sensor, 21, 23, 33.37... Subtraction circuit,
40 ・Servo controller.

Claims (1)

[Claims] (1) Head side port of fluid cylinder (3) and pressure source (
1), and also connect between the pressure source (1) and the 3-port servo valve (5) and the rod side port of the fluid cylinder (3). a position deviation subtraction circuit (1) which calculates the deviation between the position signal from the position detector (7) for detecting the position of the piston rod of the fluid cylinder (3) and the position command signal; 21) in a reciprocating drive device that controls the 3-port servo valve (5) by a position deviation signal from the fluid cylinder (3); (3) A signal representing the fluid pressure on the head side that makes the pressing force on the piston from the head side equal to the pressing force of the fluid on the piston from the rod side, and the output signal from the pressure sensor (31). Subtraction circuit for pressure deviation (33) that calculates the pressure deviation of
and calculate the deviation between the pressure deviation signal output from the pressure deviation subtraction circuit (33) and the position deviation signal output from the position deviation subtraction circuit (21), and generate a signal representing this deviation. A subtraction circuit (37) is provided to output to the 3-port servo valve (5), and a pressing force on the piston due to fluid pressure on the piston rod side of the fluid cylinder (3) and a pressing force on the piston due to fluid pressure on the head side. A reciprocating drive device characterized in that pressure feedback is performed so that