阅读说明：本技术 执行器的动作检测装置 (Actuator operation detection device ) 是由 近藤健元 于 2019-08-21 设计创作，主要内容包括：本发明提供一种不论动作节拍的速度如何都能准确地监视活塞的动作、而且能防止信息处理的延迟的执行器的动作检测装置。本发明的执行器的动作检测装置(20)监视执行器(10)中的活塞(102)的动作,所述执行器(10)的双作用气压缸(101)内被活塞(102)划分为第1压力作用室(103)和第2压力作用室(104),在活塞(102)的第2压力作用室侧端面(102b)连结有活塞杆(105),该执行器的动作检测装置(20)具备：第1压力检测器(202)及第2压力检测器(203),所述第1压力检测器(202)检测第1压力作用室(103)的压力,所述第2压力检测器(203)检测第2压力作用室(104)的压力；差动放大电路(205),其根据第1压力检测器(202)和第2压力检测器(203)检测到的压力以及活塞(102)的受压面积来算出作用于活塞(102)的推力(F)；以及微电脑(201),其根据推力(F)来监视活塞(102)的动作。(The invention provides an actuator motion detection device capable of accurately monitoring the motion of a piston regardless of the velocity of the motion beat and preventing the delay of information processing. An actuator motion detection device (20) according to the present invention monitors the motion of a piston (102) in an actuator (10), wherein the interior of a double-acting pneumatic cylinder (101) of the actuator (10) is divided by the piston (102) into a 1 st pressure acting chamber (103) and a 2 nd pressure acting chamber (104), and a piston rod (105) is connected to a 2 nd pressure acting chamber side end surface (102b) of the piston (102), the actuator motion detection device (20) comprising: a 1 st pressure detector (202) and a 2 nd pressure detector (203), wherein the 1 st pressure detector (202) detects the pressure of the 1 st pressure acting chamber (103), and the 2 nd pressure detector (203) detects the pressure of the 2 nd pressure acting chamber (104); a differential amplification circuit (205) that calculates a thrust force (F) acting on the piston (102) from the pressures detected by the 1 st pressure detector (202) and the 2 nd pressure detector (203) and the pressure receiving area of the piston (102); and a microcomputer (201) for monitoring the operation of the piston (102) on the basis of the thrust force (F).)

1. An actuator motion detection device that monitors the motion state of a piston in an actuator, the actuator comprising: a double-acting pneumatic cylinder; a piston slidably retained within the double acting pneumatic cylinder dividing a space within the double acting pneumatic cylinder into a 1 st pressure apply chamber and a 2 nd pressure apply chamber; and a piston rod coupled to an end surface of the piston on a side facing the 2 nd pressure acting chamber; the actuator operation detection device is characterized by comprising:

a 1 st pressure detector that detects a pressure of the 1 st pressure application chamber;

a 2 nd pressure detector that detects a pressure of the 2 nd pressure acting chamber;

a calculator that calculates a thrust force acting on the piston from the pressure detected by the 1 st pressure detector, the pressure detected by the 2 nd pressure detector, and a pressure receiving area of the piston; and

and a monitor for confirming the operating state of the piston based on the thrust.

2. The actuator motion detection device according to claim 1,

the calculator calculates the thrust force in consideration of a fact that a pressure receiving area of an end surface of the piston facing the 2 nd pressure acting chamber is smaller than a pressure receiving area of an end surface of the piston facing the 1 st pressure acting chamber by an outer diameter of the piston rod,

the monitor confirms the action state of the piston according to the sign of the thrust.

3. The actuator motion detection device according to claim 1 or 2,

the monitor confirms the action state of the piston according to the change rate of the thrust.

4. The actuator motion detection device according to any one of claims 1 to 3,

the monitor determines whether the piston has started moving or has stopped moving, and, in the case where it is determined that the piston has started moving, determines whether the piston is moving toward the end face of the double-acting pneumatic cylinder on the side facing the 1 st pressure acting chamber or the side facing the 2 nd pressure acting chamber.

Technical Field

The present invention relates to a motion detection device of an actuator which monitors a motion state of a piston in the actuator, the actuator having a double-acting pneumatic cylinder, a space in the double-acting pneumatic cylinder being divided into a 1 st pressure acting chamber and a 2 nd pressure acting chamber by a piston slidably held in the double-acting pneumatic cylinder, a piston rod being coupled to an end surface (2 nd piston end surface) of the piston on a side facing the 2 nd pressure acting chamber.

Background

The control of mechanical arms used in food factories and the like generally uses actuators having double-acting pneumatic cylinders. The interior of the double-acting pneumatic cylinder is divided by the piston into a 1 st pressure acting chamber and a 2 nd pressure acting chamber, and one end of a pipe for feeding or discharging compressed air is connected to each of the 1 st pressure acting chamber and the 2 nd pressure acting chamber. A compressed air supply source is connected to the other end of the pipe via a switching valve, and the switching valve switches between the intake air to the 1 st pressure acting chamber and the intake air to the 2 nd pressure acting chamber, thereby reciprocating the piston in the pneumatic cylinder.

Here, the piston rod is connected to the 2 nd piston end surface of the piston. Further, the movement of the piston toward the end surface of the double-acting pneumatic cylinder facing the 2 nd pressure acting chamber (the 2 nd cylinder end surface) and the movement of the piston rod in the direction protruding from the double-acting pneumatic cylinder are regarded as forward movement, and the movement of the piston toward the end surface of the double-acting pneumatic cylinder facing the 1 st pressure acting chamber (the 1 st cylinder end surface) and the movement of the piston rod in the direction of being housed in the double-acting pneumatic cylinder are regarded as backward movement.

In the double-acting pneumatic cylinder as described above, conventionally, a magnet is incorporated in a piston rod, and a magnetic detection sensor is disposed at one end and the other end of a double-acting pneumatic cylinder main body, thereby detecting whether or not a piston has reached the 1 st cylinder end face or the 2 nd cylinder end face of the double-acting pneumatic cylinder main body and monitoring the reciprocating motion of the piston.

However, in a food factory, there is a possibility that a cleaning liquid for food or the like adheres to the double-acting pneumatic cylinder main body, and when the adhesion of the cleaning liquid occurs, there is a possibility that the magnetic detection sensor or the line of the magnetic detection sensor is corroded.

Therefore, as shown in patent document 1, an operation detection device using an actuator is used which detects a 1 st pressure value of a fluid in a pipe connected to a 1 st pressure operation chamber and a 2 nd pressure value of a fluid in a pipe connected to a 2 nd pressure operation chamber, and monitors whether a differential pressure between the 1 st pressure value of the 1 st pressure operation chamber and the 2 nd pressure value of the 2 nd pressure operation chamber is a positive value or a negative value, thereby monitoring whether a piston has reached a 1 st cylinder end face or a 2 nd cylinder end face of a double-acting cylinder main body.

That is, since the 1 st pressure value is larger than the 2 nd pressure value during the forward movement of the piston and the 2 nd pressure value is larger than the 1 st pressure value during the backward movement of the piston, the differential pressure obtained by subtracting the 2 nd pressure value from the 1 st pressure value is a positive value during the forward movement of the piston and a negative value during the backward movement of the piston. Therefore, when the differential pressure is a positive value, it can be determined that the piston is moving forward, and when the differential pressure is a negative value, it can be determined that the piston is moving backward. Further, since the differential pressure abruptly changes when the piston reaches one end of the double-acting pneumatic cylinder and completes the forward movement or the backward movement, it can be determined that the piston has reached one end of the double-acting pneumatic cylinder by capturing the abrupt change of the differential pressure.

Therefore, by observing whether the differential pressure is a positive value or a negative value before the differential pressure abruptly changes, it is possible to determine which end of the double-acting pneumatic cylinder the piston has reached.

Further, when the double-acting pneumatic cylinder is relatively small, since the volumes of the 1 st pressure acting chamber and the 2 nd pressure acting chamber are small, pressure fluctuations of the 1 st pressure value and the 2 nd pressure value at the time of switching between the pressing (push) operation and the pulling (pull) operation of the piston may be relatively small, and erroneous detection may occur due to noise. Therefore, as shown in patent document 2, an actuator operation detection device is used which performs time differentiation on the pressure value to monitor the rate of change in the pressure value and to monitor whether or not the piston has reached the 1 st cylinder end face or the 2 nd cylinder end face of the double-acting cylinder main body.

According to the operation detection device of the actuator, it is not necessary to dispose the magnetic detection sensor and the line for the magnetic detection sensor near the double-acting pneumatic cylinder, and there is no fear that the magnetic detection sensor or the line of the magnetic detection sensor is corroded by the cleaning liquid used in the food factory.

[ Prior art documents ]

[ patent document ]

[ patent document 1 ] International patent publication No. 2017/187934

[ patent document 2 ] Japanese patent laid-open No. 2018-59549

Disclosure of Invention

[ problem to be solved by the invention ]

However, the above-described prior art has, for example, the following problems.

< problem 1 >

The applicant of the present application has found that, in the operation detection device of the actuator for monitoring the operation of the piston based on the pressure value disclosed in patent document 1, when the operation beat (operating beat) is slowed down by the speed controller, the operation of the piston cannot be monitored accurately.

For example, the switching cycle of the switching valve is 1sec, whereas the exhaust gas amount is limited by the speed controller to slow down the operation cycle of the piston to 900msec, at this time, as shown in fig. 5, an electric signal is sent to the solenoid of the switching valve (time t0), the switching valve is switched (time t1), intake to the 1 st pressure operation chamber is started, the 1 st pressure value P1 starts to rise, exhaust of the 2 nd pressure operation chamber is started, the 2 nd pressure value P2 starts to decrease, but the 1 st pressure value P1 and the 2 nd pressure value P2 are not inverted, and the forward movement of the piston is started in a state where the 2 nd pressure value P2 is greater than the 1 st pressure value P1 (time t 3).

The reason why the piston starts the forward movement in the state where the 2 nd pressure value P2 is larger than the 1 st pressure value P1 is that when the displacement is limited by the speed controller, the 2 nd pressure value P2 of the 2 nd pressure operation chamber on the displacement side is maintained higher than in the case where the displacement is not limited, and the pressure receiving area of the 2 nd piston end surface of the piston is smaller than the other end surface (the 1 st piston end surface) of the piston by the connection area of the piston rod, so that even in the state where the 2 nd pressure value P2 is higher than the 1 st pressure value P1, the force acting on the 2 nd piston end surface of the piston (hereinafter referred to as the 2 nd acting force F2) can advance while being lower than the force acting on the 1 st piston end surface (hereinafter referred to as the 1 st acting force F1).

Then, when the forward movement of the piston is completed (time t4), the 1 st pressure value P1 rises and the 2 nd pressure value P2 decreases, but immediately after that, an electric signal is sent to the solenoid of the switching valve (time t5), the switching valve switches, and the air intake to the 2 nd pressure acting chamber and the air exhaust from the 1 st pressure acting chamber are started (time t 6). Then, the decrease of the 2 nd pressure value P2 is stopped, and the 1 st pressure value P1 starts to decrease, so that the piston starts the backward movement without the 1 st pressure value P1 and the 2 nd pressure value P2 being reversed.

In the whole forward movement and the backward movement of the piston, the 1 st pressure value P1 and the 2 nd pressure value P2 are not reversed, so the 1 st pressure value P1 is always smaller than the 2 nd pressure value P2, and the differential pressure obtained by subtracting the 2 nd pressure value P2 from the 1 st pressure value P1 is always negative. Therefore, it is impossible to determine whether the piston is moving forward or backward from the sign of the differential pressure, and the operation of the piston cannot be monitored accurately.

The applicant of the present application therefore thought that the motion of an object was dependent on the thrust acting on the object, and there was a limit to monitoring the motion of the piston based on the pressure value, leading to the conclusion that it is desirable to monitor the motion of the piston based on the thrust acting on the piston. Because the following relationship exists: the 1 st force F1 of the piston is greater than the 2 nd force F2 when the piston is moving forward and the 2 nd force F2 of the piston is greater than the 1 st force F1 when the piston is moving backward. This relationship does not change at any beat of motion, and it is clear whether the thrust acts in the forward direction or the reverse direction of the piston.

< problem 2 >

In the actuator operation detection device disclosed in patent document 2, there is a possibility that a delay occurs in information processing by a microcomputer incorporated in the actuator operation detection device.

For example, when the 1 st pressure value P1 and the 2 nd pressure value P2 are subjected to time differentiation to monitor the rate of change in pressure value and monitor whether or not the piston has reached the 1 st cylinder end face or the 2 nd cylinder end face of the double-acting cylinder main body, as shown in fig. 6, the time differential value dP1 of the 1 st pressure value P1 in the 1 st pressure working chamber greatly changes in the positive direction (from the negative side to the positive side) immediately before the start of the operation of the piston (time t3), while the change at the end of the operation (time t4) is small, so that the detection at the start of the operation is relatively easy, but the detection at the end of the operation may be erroneously detected due to noise. As shown in fig. 7, the time differential dP2 of the 2 nd pressure value P2 of the 2 nd pressure working chamber varies little immediately before the start of the operation of the piston (time t3), but varies greatly in the negative direction immediately before the end of the operation (time t4), and therefore detection at the end of the operation is relatively easy, but detection at the start of the operation may be erroneously detected due to noise.

In order to reliably detect the start and end of the operation and prevent erroneous detection due to the noise, it is necessary to monitor both the rate of change of the 1 st pressure value P1 and the rate of change of the 2 nd pressure value P2 in parallel so as to detect the start of the operation by the rate of change of the 1 st pressure value P1 and the end of the operation by the rate of change of the 2 nd pressure value P2, and there is a possibility that the information processing of the microcomputer incorporated in the operation detecting device of the actuator is delayed.

The present invention has been made to solve the above problems 1 and 2, and an object of the present invention is to provide an actuator operation detection device capable of accurately monitoring the operation of a piston regardless of the speed of the operation tempo and preventing a delay in information processing.

[ MEANS FOR SOLVING PROBLEMS ] A method for producing a semiconductor device

(1) In order to solve the above-described problems, according to one aspect of the present invention, there is provided a motion detection device for an actuator that monitors a motion state of a piston in the actuator, the actuator including a double-acting pneumatic cylinder, a space in the double-acting pneumatic cylinder being partitioned into a 1 st pressure acting chamber and a 2 nd pressure acting chamber by the piston slidably held in the double-acting pneumatic cylinder, and a piston rod being connected to an end surface of the piston on a side facing the 2 nd pressure acting chamber, the motion detection device for the actuator comprising: a 1 st pressure detector that detects a pressure of the 1 st pressure acting chamber; a 2 nd pressure detector that detects a pressure of the 2 nd pressure acting chamber; a calculator that calculates a thrust force acting on the piston from the pressure detected by the 1 st pressure detector, the pressure detected by the 2 nd pressure detector, and the pressure receiving area of the piston; and a monitor for confirming the operating state of the piston based on the thrust.

According to the above configuration (1), the 1 st pressure detector and the 2 nd pressure detector detect the pressure of the 1 st pressure operation chamber and the pressure of the 2 nd pressure operation chamber, respectively, and the calculator calculates the thrust force acting on the piston from the pressure of the 1 st pressure operation chamber, the pressure of the 2 nd pressure operation chamber, and the pressure receiving area of the piston. Then, the monitor can confirm the operating state of the piston from the calculated thrust. The following relationships exist: when the piston moves forwards, the 1 st acting force of the piston is larger than the 2 nd acting force, and when the piston moves backwards, the 2 nd acting force is larger than the 1 st acting force. Since this relationship does not change with the speed of the operation tempo, the forward movement or the backward movement of the piston becomes clear by calculating the thrust force acting on the piston, and the piston operation can be accurately monitored regardless of the speed of the operation tempo.

The respective US/EP applications only recite the independent claims

(2) The actuator operation detection device according to (1) above, wherein the calculator calculates the thrust force in consideration of the fact that the pressure receiving area of the end surface of the piston facing the 2 nd pressure operation chamber is smaller than the pressure receiving area of the end surface of the piston facing the 1 st pressure operation chamber by the outer diameter of the piston rod, and the monitor confirms the operation state of the piston from the sign of the thrust force.

According to the above configuration (2), since the piston rod is connected to the end surface of the piston facing the 2 nd pressure acting chamber (the 2 nd piston end surface), the thrust force is calculated in consideration of the fact that the pressure receiving area is smaller than the pressure receiving area of the end surface of the piston facing the 1 st pressure acting chamber (the 1 st piston end surface) by the outer diameter of the piston rod.

Here, the thrust force is a value obtained by subtracting a product value of the 2 nd pressure value and the pressure receiving area ratio from the 1 st pressure value.

The pressure receiving area ratio is a ratio of a pressure receiving area of the 2 nd piston end surface of the piston to a pressure receiving area of the 1 st piston end surface, and for example, in the case of a piston diameter of 25mm and a piston rod diameter of 12mm, the ratio of the pressure receiving area of the 2 nd pressure acting chamber side to the pressure receiving area of the 1 st pressure acting chamber side of the piston is about 0.75. That is, the value obtained by subtracting the product of the 2 nd pressure value and 0.75 from the 1 st pressure value becomes the thrust acting on the piston. The pressure receiving area ratio varies according to the specifications inherent to the actuator, such as the piston diameter and the piston rod diameter.

When the piston is monitored for reciprocation according to the pressure, when the piston moves forward in a state where the displacement is controlled by the speed controller, the pressure receiving area of the 2 nd piston end surface of the piston is smaller than the connecting area of the piston rod, and therefore, even in a state where the 2 nd pressure value of the 2 nd pressure operation chamber is higher than the 1 st pressure value of the 1 st pressure operation chamber, the force acting on the 2 nd piston end surface can move forward lower than the force acting on the 1 st piston end surface of the piston. Therefore, there may be a case where the reciprocating motion of the piston cannot be accurately monitored based on the magnitude relationship between the 1 st pressure and the 2 nd pressure. On the other hand, the thrust force acting on the piston is obtained by taking the pressure receiving area into consideration, and the thrust force is always a positive value when the piston is moving forward and a negative value when the piston is moving backward.

Then, whether the piston is moving forward or backward is clear depending on whether the thrust force is a positive value or a negative value, and therefore, the monitor can accurately monitor what kind of operation the piston is performing depending on the sign of the thrust force.

(3) The actuator motion detection device according to (1) or (2), wherein the monitor confirms the motion state of the piston based on the rate of change of the thrust.

According to the above configuration (3), the monitor only needs to perform information processing based on the change rate which is the time differential value of the thrust force, and there is no need to perform information processing in parallel with the conventional technique on both the change rate of the 1 st pressure value of the 1 st pressure working chamber and the change rate of the 2 nd pressure value of the 2 nd pressure working chamber, and therefore, the possibility of delay in information processing by the microcomputer incorporated in the operation detection device of the actuator can be eliminated.

(4) The motion detecting device of the actuator according to any one of (1) to (3), wherein the monitor determines whether the piston has started moving or stopped moving, and determines whether the piston is moving toward the end surface of the double-acting pneumatic cylinder on the side facing the 1 st pressure acting chamber or the end surface of the double-acting pneumatic cylinder on the side facing the 2 nd pressure acting chamber.

According to the above configuration (4), for example, if the operation detection device of the actuator is provided with a display device, and the display device displays information obtained by the judgment of the monitor, the user can grasp the accurate operation state of the actuator, and therefore, it becomes easy to perform an operation of setting the operation tempo desired by the user while adjusting the pressure of the fluid to be fed, the speed controller, or the like.

Drawings

Fig. 1 is a circuit diagram of an actuator monitoring system using a motion detection device for an actuator.

Fig. 2 is a block diagram showing a configuration of a motion detection device of an actuator.

Fig. 3(a) is a graph showing the behavior of the 1 st pressure value and the 3 rd pressure value with the passage of time, fig. 3(b) is a graph showing the behavior of the thrust force acting on the piston with the passage of time, and fig. 3(c) is a graph showing the behavior of the time differential value of the thrust force with the passage of time.

FIG. 4 is a flowchart of the microcomputer determining the operation of the piston.

Fig. 5 is a graph showing the behavior of the 1 st pressure value and the 2 nd pressure value with the passage of time in the related art.

Fig. 6 is a graph showing the behavior of the time differential value of the 1 st pressure value with the passage of time in the conventional art.

Fig. 7 is a graph showing the behavior of the time differential value of the 2 nd pressure value with the passage of time in the conventional art.

Detailed Description

An embodiment of the actuator motion detection device 20 according to the present invention will be described in detail with reference to the drawings.

Fig. 1 is a circuit diagram of an actuator monitoring system 1 using an actuator motion detection device 20. The actuator operation detection device 20 functions as a device for monitoring the operating state of a piston 102 slidably held in a double-acting pneumatic cylinder 101 constituting the actuator 10.

The interior of double acting pneumatic cylinder 101 is divided by piston 102 into 1 st pressure acting chamber 103 and 2 nd pressure acting chamber 104. Further, a piston rod 105 is connected to an end surface (2 nd piston end surface) 102b of the piston 102 on the side facing the 2 nd pressure acting chamber 104, and the piston rod 105 extends to the outside of the double-acting pneumatic cylinder 101 through an insertion hole 101c of an end surface (2 nd cylinder end surface) 101b of the double-acting pneumatic cylinder 101 on the side facing the 2 nd pressure acting chamber 104.

One end of the 1 st pipe 11 for feeding or discharging compressed air is connected to the 1 st pressure acting chamber 103, and the other end of the 1 st pipe 11 is connected to the 1 st connection port 131 of the switching valve 13.

Also, one end of the 2 nd pipe 12 for feeding or discharging the compressed air is connected to the 2 nd pressure acting chamber 104, and the other end of the 2 nd pipe 12 is connected to the 2 nd connection port 132 of the switching valve 13.

Further, the 1 st duct 11 and the 2 nd duct 12 are provided with speed controllers 14, respectively.

The switching valve 13 has an input port 133 to which compressed air is input, one end of the intake duct 15 is connected to the input port 133, and the other end of the intake duct 15 is connected to the compressed air supply source 16.

In the present embodiment, the switching valve 13 is a solenoid-type solenoid valve, and an internal valve body (not shown) is driven by applying an electric signal to the solenoids 134A and 134B from the outside.

When an electric signal is applied to the solenoid 134A, the spool of the switching valve 13 is attracted to the solenoid 134A side, the input port 133 communicates with the 1 st connection port 131, and the 2 nd connection port 132 is opened to the outside.

The input port 133 communicates with the 1 st connection port 131 so that the compressed air supplied from the compressed air supply source 16 is input from the input port 133 to the switching valve 13 and is output from the 1 st connection port 131. The compressed air output from the 1 st connection port 131 is fed through the 1 st pipe 11 to the 1 st pressure acting chamber 103 of the double-acting pneumatic cylinder 101.

The compressed air is fed to the 1 st pressure acting chamber 103 so that the pressure inside the 1 st pressure acting chamber 103 rises, the end surface (1 st piston end surface) 102a of the piston 102 on the side facing the 1 st pressure acting chamber 103 is pressed, and the piston 102 moves in the forward direction (arrow X in the drawing). The exhaust of the 2 nd pressure acting chamber 104 is started while the piston 102 is moved in the forward direction, and the compressed air previously fed to the 2 nd pressure acting chamber 104 is exhausted to the outside via the 2 nd pipe 12, the 2 nd connection port 132, and the switching valve 13.

On the other hand, when an electric signal is applied to the solenoid 134B, the spool of the switching valve 13 is attracted to the solenoid 134B side, the input port 133 communicates with the 2 nd connection port 132, and the 1 st connection port 131 is opened to the outside.

The input port 133 communicates with the 2 nd connection port 132 so that the compressed air supplied from the compressed air supply source 16 is input from the input port 133 to the switching valve 13 and is output from the 2 nd connection port 132. The compressed air output from the 2 nd connecting port 132 is fed to the 2 nd pressure acting chamber 104 of the double acting pneumatic cylinder 101 through the 2 nd pipe 12.

The compressed air is supplied to the 2 nd pressure operation chamber 104 to increase the pressure inside the 2 nd pressure operation chamber 104, the 2 nd piston end surface 102b of the piston 102 is pressed, and the piston 102 moves in the retreating direction (arrow Y in the figure). The piston 102 moves in the retreating direction, and the 1 st pressure operation chamber 103 starts to be exhausted, and the compressed air previously fed to the 1 st pressure operation chamber 103 is exhausted to the outside through the 1 st pipe 11, the 1 st connection port 131, and the switching valve 13.

By driving the spool by energization of the solenoids 134A, 134B of the switching valve 13, feeding of the compressed air to the 1 st pressure acting chamber 103 and feeding of the compressed air to the 2 nd pressure acting chamber 104 can be switched, and by repeating this switching, the piston 102 can be reciprocated. Then, the piston rod 105 connected to the 2 nd piston end surface 102b of the piston 102 reciprocates as the piston 102 reciprocates.

An actuator operation detection device 20 is connected to the 1 st and 2 nd pipes 11 and 12 and between the speed controller 14 and the actuator 10, and sequentially detects the 1 st pressure value P1 of the 1 st pipe 11 and the 2 nd pressure value P2 of the 2 nd pipe 12, and monitors the operation of the piston 102 of the actuator 10.

Next, the configuration of the actuator operation detection device 20 will be described. Fig. 2 is a block diagram showing the configuration of the actuator operation detection device 20.

The actuator operation detection device 20 includes a microcomputer 201, a 1 st pressure detector 202, a 2 nd pressure detector 203, a differential amplifier circuit 205, a display unit 206, a setting unit 207, a communication unit 208, and a signal output circuit 209.

The 1 st pressure detector 202 is connected to the 1 st pipe 11, and detects the pressure of the compressed air in the 1 st pipe 11, i.e., the 1 st pressure value P1. The 2 nd pressure detector 203 is connected to the 2 nd pipe 12, and detects a 2 nd pressure value P2, which is the pressure of the compressed air in the 2 nd pipe 12. Since the pressure in the 1 st line 11 varies according to the pressure in the 1 st pressure operation chamber 103 and the pressure in the 2 nd line 12 varies according to the pressure in the 2 nd pressure operation chamber 104, the pressure values detected in the 1 st line 11 and the 2 nd line 12 are synonymous with the pressure values detected in the 1 st pressure operation chamber 103 and the 2 nd pressure operation chamber 104.

The 1 st pressure detector 202 is connected to the differential amplifier circuit 205, and outputs a signal corresponding to the 1 st pressure value P1 detected by the differential amplifier circuit 205.

The 2 nd pressure detector 203 is connected to the differential amplifier circuit 205 via a voltage divider 204, and a signal corresponding to the 2 nd pressure value P2 detected by the 2 nd pressure detector 203 is divided by the voltage divider 204 and input to the differential amplifier circuit 205. That is, since the piston rod 105 is connected, the pressure receiving area of the 2 nd piston end surface 102b of the piston 102 is smaller than the pressure receiving area of the 1 st piston end surface 102a by the degree of the outer diameter (i.e., the degree of the sectional area) of the piston rod 105. The pressure divider 204 divides a signal corresponding to the 2 nd pressure value P2 according to the ratio of the pressure receiving area of the 1 st piston end surface 102a to the pressure receiving area of the 2 nd piston end surface 102b, and outputs the signal as the 3 rd pressure value P3.

For example, in the case of a piston diameter of 25mm and a piston rod diameter of 12mm, the ratio of the pressure receiving area of the 2 nd piston end surface 102b to the pressure receiving area of the 1 st piston end surface 102a of the piston 102 is about 0.75. Therefore, the value obtained by multiplying the 2 nd pressure value P2 by 0.75 becomes the 3 rd pressure value P3.

Then, the differential amplifier circuit 205 calculates the difference obtained by subtracting the 3 rd pressure value P3 from the 1 st pressure value P1. This difference becomes a thrust force F acting on the piston 102. The differential amplifier circuit 205 is an example of the calculator of the present invention.

The following relationships exist: the force acting on the 1 st piston end surface 102a of the piston 102 is larger than the force acting on the 2 nd piston end surface 102b during the forward movement of the piston 102, and the force acting on the 2 nd piston end surface 102b is larger than the force acting on the 1 st piston end surface 102a during the backward movement of the piston 102. This relationship does not change with the speed of the action beat.

Regarding the thrust force F, which is the difference obtained by subtracting the 3 rd pressure value P3 from the 1 st pressure value P1, the thrust force F is always a positive value when the piston 102 is moving forward, and the thrust force F is always a negative value when the piston 102 is moving backward.

The differential amplifier circuit 205 is connected to the microcomputer 201, and the thrust force F acting on the piston 102 calculated by the differential amplifier circuit 205 is input to the microcomputer 201. Then, the microcomputer 201 monitors the operation of the piston 102 based on the thrust force F. The microcomputer 201 is an example of the monitor of the present invention.

More specifically, the microcomputer 201 performs a process of determining whether the piston 102 is moving forward or backward, based on the sign of the thrust force F input from the differential amplifier circuit 205. Since it becomes clear whether the piston 102 is moving forward or backward depending on whether the thrust force F is a positive value or a negative value, the piston operation can be accurately monitored regardless of the speed of the operation beat.

Further, the microcomputer 201 can determine whether the piston 102 has started moving or stopped moving based on the rate of change of the thrust force F input from the differential amplifier circuit 205.

The microcomputer 201 time-differentiates the thrust force F input from the differential amplifier circuit 205, and calculates a differential value dF which is a change rate of the thrust force F.

The microcomputer 201 monitors whether or not the differential value dF rapidly changes in the positive direction or the negative direction with the passage of time, and determines whether the movement of the piston 102 has started or stopped when the rapid change in the differential value dF is captured. Since the microcomputer 201 determines the operation of the piston 102 based on the differential value dF of the thrust force F, it is not necessary to perform information processing on both the differential value of the 1 st pressure acting chamber and the differential value of the 2 nd pressure acting chamber in parallel as in the conventional technique. Therefore, the delay in the information processing of the microcomputer 201 can be eliminated.

The display unit 206, the communication unit 208, and the signal output circuit 209 are connected to the microcomputer 201, and information obtained by the determination processing performed by the microcomputer 201 can be displayed on the display unit 206 or can be output to the outside via the communication unit 208 or the signal output circuit 209.

Since the information obtained by the determination process performed by the microcomputer 201 is displayed on the display unit 206 or is output to the outside, the user can grasp the exact operating state of the actuator 10, and therefore, it is easy to perform an operation of setting the operating tempo desired by the user while adjusting the pressure of the fluid to be fed or the speed controller 14.

Further, the microcomputer 201 is connected to a setting unit 207, which allows a user to input and set information necessary for the determination process in the microcomputer 201, such as the piston diameter. Further, information necessary for the microcomputer 201 to perform the judgment processing of the movement of the piston 102 may be inputted from the outside via the communication unit 208.

Next, the behavior of the 1 st pressure value P1 and the 3 rd pressure value P3 with respect to the elapse of time will be described. Fig. 3(a) is a graph showing the behavior of the 1 st pressure value P1 and the 3 rd pressure value P3 in the following cases: the switching cycle of the switching valve 13 is 1sec, whereas the displacement is adjusted by the speed controller 14 to set the operation cycle of the piston 102 to 900 msec.

At a time point t0 in fig. 3, an electric signal is applied to the solenoid 134A. When an electric signal is applied to the solenoid 134A, the spool of the switching valve 13 is attracted to the solenoid 134A side, the input port 133 communicates with the 1 st connection port 131, and the 2 nd connection port 132 is opened to the outside (time point t1 in fig. 3).

The input port 133 communicates with the 1 st connection port 131 so that the compressed air supplied from the compressed air supply source 16 is input from the input port 133 to the switching valve 13 and is output from the 1 st connection port 131. The compressed air output from the 1 st connection port 131 is fed to the 1 st pressure acting chamber 103 through the 1 st pipe 11.

On the other hand, the 2 nd pressure operation chamber 104 communicates with the atmosphere via the 2 nd pipe 12 and the switching valve 13, and the discharge of the compressed air is started (time point t1 in fig. 3).

The 1 st pressure operation chamber 103 is supplied with air so that the 1 st pressure value P1 of the 1 st pipe 11 connected to the 1 st pressure operation chamber 103 rises rapidly. On the other hand, starting the exhaust of the 2 nd pressure acting chamber 104 causes the 2 nd pressure value P2 of the 2 nd piping 12 connected to the 2 nd pressure acting chamber 104 to decrease, and therefore the 3 rd pressure value P3 also decreases.

Then, at the time point t2 in fig. 3, the 1 st pressure value P1 and the 3 rd pressure value P3 are reversed, and thereafter, at the time point t3, the piston 102 starts to advance.

As piston 102 begins its forward motion, pressure value 1P 1 and pressure value 3P 3 slowly rise until point in time t4 at which piston 102 reaches cylinder end face 2b of double-acting pneumatic cylinder 101.

When piston 102 reaches cylinder 2 end face 101b of double acting cylinder 101, piston 102 stops. When the piston 102 stops, the 1 st pressure value P1 slowly rises and the 2 nd pressure value P2 sharply decreases.

Next, at a time point t5 in fig. 3, an electric signal is applied to the solenoid 134B. When an electric signal is applied to the solenoid 134B, the spool of the switching valve 13 is attracted to the solenoid 134B side, the input port 133 communicates with the 2 nd connection port 132, and the 1 st connection port 131 is opened to the outside (time point t6 in fig. 3).

The input port 133 communicates with the 2 nd connection port 132 so that the compressed air supplied from the compressed air supply source 16 is input from the input port 133 to the switching valve 13 and is output from the 2 nd connection port 132. The compressed air output from the 2 nd connection port 132 is fed to the 2 nd pressure acting chamber 104 through the 2 nd pipe 12.

On the other hand, the 1 st pressure operation chamber 103 communicates with the atmosphere via the 1 st pipe 11 and the switching valve 13, and the discharge of the compressed air is started.

The 2 nd pressure operation chamber 104 is supplied with air so that the 2 nd pressure value P2 of the 2 nd pipe 12 connected to the 2 nd pressure operation chamber 104 rapidly rises, and therefore the 3 rd pressure value P3 also rapidly rises. On the other hand, starting the exhaust of the 1 st pressure acting chamber 103 causes the 1 st pressure value P1 of the 1 st pipe 11 connected to the 1 st pressure acting chamber 103 to decrease.

Then, at the time point t7 in the figure, the 1 st pressure value P1 and the 3 rd pressure value P3 are reversed, and thereafter, at the time point t8, the piston 102 starts the backward movement.

When the piston 102 starts the retreating movement, the 1 st pressure value P1 and the 3 rd pressure value P3 slowly rise until a time point t9 at which the piston 102 reaches the end surface (1 st cylinder end surface) 101a of the double-acting pneumatic cylinder 101 on the side facing the 1 st pressure acting chamber.

When the piston 102 reaches the 1 st cylinder end face 101a of the double acting cylinder 101, the piston 102 stops. When the piston 102 stops, the 3 rd pressure value P3 slowly rises and the 1 st pressure value P1 sharply decreases.

Then, at a time point t10 in fig. 3, an electric signal is applied to the solenoid 134A, and thereafter, the behavior is the same as that of t0 to t10 in fig. 3.

The thrust force F acting on the piston 102 is obtained from the behavior of the 1 st pressure value P1 and the 3 rd pressure value P3 as described above with the passage of time, and is shown as a graph in fig. 3 (b). Specifically, the thrust force F is obtained by subtracting the 3 rd pressure value P3, which is the product of the 2 nd pressure value P2 and the pressure receiving area ratio, from the 1 st pressure value P1. The pressure receiving area ratio is a ratio of the pressure receiving area of the 2 nd piston end surface 102b of the piston 102 to the pressure receiving area of the 1 st piston end surface 102a, and is considered to be a content that the pressure receiving area of the 2 nd piston end surface 102b of the piston 102 is smaller than the 1 st piston end surface 102a by the connecting area of the piston rod 105. For example, when the piston diameter is 25mm and the piston rod diameter is 12mm, the pressure receiving area ratio is about 0.75.

The behavior of the thrust force F with the passage of time will be specifically described. At a time point t0 when an electric signal is sent to the solenoid 134A of the selector valve 13, the thrust force F takes a negative value since the piston 102 performs the backward movement before that. At time t1, the switching of the switching valve 13 starts the intake to the 1 st pressure acting chamber 103 and the exhaust to the 2 nd pressure acting chamber 104, and the thrust force F acting on the piston 102 sharply increases in the positive direction. At a time point t2, the thrust force F exceeds 0, and thereafter from a time point t3, the piston 102 starts advancing movement. After the forward movement of the piston 102 is started, the thrust force F gradually decreases until a time point t4 when the forward movement of the piston 102 is completed, and after the forward movement of the piston 102 is completed, an electric signal is sent to the solenoid 134B (time point t5), and the thrust force F rises until a time point t6 when the switching valve 13 is switched.

When the switching valve 13 is switched, the intake to the 2 nd pressure acting chamber 104 is started and the exhaust from the 1 st pressure acting chamber 103 is started, so that the thrust force F acting on the piston 102 abruptly changes in the negative direction. Then, at time t7, the thrust force F becomes 0 or less, and from time t8, the piston 102 starts moving backward. Thereafter, the thrust force F slowly decreases until a time point t9 at which the rearward movement of the piston 102 is completed. Then, when the retreat movement of the piston 102 is completed, the thrust force F sharply drops.

Since the thrust force F when the piston 102 is moving forward is a positive value and the thrust force F when the piston 102 is moving backward is a negative value, the microcomputer 201 can determine whether the piston 102 is moving forward or backward based on whether the thrust force F is a positive value or a negative value, and can accurately monitor the movement of the piston 102 regardless of the speed of the movement beat.

The time differential value dF of the thrust force F is obtained, and the graph of fig. 3(c) shows the behavior of the differential value dF with the passage of time.

The behavior of the differential value dF with the passage of time will be specifically described.

In the period from the switching time point (t0) of the switching valve 13 to the time point (t3) at which the forward movement of the piston 102 starts, the differential value dF changes abruptly toward the positive direction (from the negative side toward the positive side) with an abrupt increase in the thrust force F. The differential value dF is maintained at substantially 0 from the start of the forward movement of the piston 102 to just before the time t4 at which the forward movement is completed, and abruptly changes in the negative direction after the completion of the forward movement.

Thereafter, the differential value dF gradually rises toward 0 until t5 when the electric signal is sent to the solenoid 134B, and rapidly changes in the positive direction at time t 5. Thereafter, the piston 102 is lowered substantially toward 0 until a time point t8 at which the piston starts the backward movement. The reverse movement of the piston 102 is maintained at substantially 0 immediately before the time point t9 at which the reverse movement is completed, and the direction thereof is abruptly changed to the positive direction after the reverse movement is completed. Thereafter, the temperature is gradually decreased toward 0 until a switching time t10 of the switching valve 13.

The microcomputer 201 calculates a time differential value dF with respect to the thrust force F sequentially input from the differential amplifier circuit 205, and determines whether the piston 102 has started moving or stopped moving by capturing a sudden change in the positive direction or the negative direction of the differential value dF. Since it is not necessary to perform information processing on both the differential value of the 1 st pressure operation chamber and the differential value of the 2 nd pressure operation chamber in parallel as in the conventional technique, the delay in information processing by the microcomputer 201 can be eliminated.

Fig. 4 is a flowchart for determining the operation of the piston 102 based on the sign of the thrust force F and the time differential value dF.

The microcomputer 201 calculates the time differential value dF from the thrust force F sequentially input, and determines whether or not the calculated time differential value dF is abruptly changed (S1). When the time differential value dF changes abruptly (S1: yes), the microcomputer 201 determines that the piston 102 has started moving from one end of the double-acting pneumatic cylinder 101 to the other end (S2), and the microcomputer 201 displays the determination result on the display unit 206 and notifies the user of the determination result (S3).

Thereafter, the microcomputer 201 determines whether the thrust force F is a positive value (S4). When the thrust force F is a positive value (S4: YES), the microcomputer 201 determines that the piston 102 is moving forward (S5), and the microcomputer 201 displays the determination result on the display unit 206 and notifies the user of the determination result (S6).

Next, the microcomputer 201 determines whether or not the time differential dF has abruptly changed (S7). When the time differential value dF changes abruptly (S7: yes), the microcomputer 201 determines that the piston 102 has reached one end of the double-acting pneumatic cylinder 101 and stopped moving (S8), and the microcomputer 201 displays the determination result on the display unit 206 and notifies the user of the determination result (S9).

On the other hand, when the microcomputer 201 determines in S4 that the thrust F is not a positive value (S4: no), the microcomputer 201 determines whether the thrust F is a negative value (S10). When the thrust force F is a negative value (S10: YES), the microcomputer 201 determines that the piston 102 is moving backward (S11), and the microcomputer 201 displays the determination result on the display unit 206 and notifies the user of the determination result (S12).

Next, the microcomputer 201 determines whether or not the time differential dF has abruptly changed (S13). When the time differential value dF changes abruptly (S13: yes), the microcomputer 201 determines that the piston 102 has reached one end of the double-acting pneumatic cylinder 101 and stopped moving (S14), and the microcomputer 201 displays the determination result on the display unit 206 and notifies the user of the determination result (S15).

Since the thrust force F when the piston 102 is moving forward is a positive value and the thrust force F when the piston 102 is moving backward is a negative value, the microcomputer 201 can determine whether the piston 102 is moving forward or backward based on whether the thrust force F is a positive value or a negative value, and can accurately monitor the movement of the piston 102 regardless of the speed of the movement beat.

The microcomputer 201 calculates a time differential value dF with respect to the thrust force F sequentially input from the differential amplifier circuit 205, and determines whether the piston 102 has started moving or stopped moving by capturing a sudden change in the positive direction or the negative direction of the differential value dF. Since it is not necessary to perform information processing on both the differential value of the 1 st pressure operation chamber and the differential value of the 2 nd pressure operation chamber in parallel as in the conventional technique, the delay in information processing by the microcomputer 201 can be eliminated.

(1) As described above, the actuator operation detection device 20 according to the present embodiment has the following configuration. An actuator operation detection device 20 for monitoring an operation state of a piston 102 in an actuator 10, the actuator 10 having a double-acting pneumatic cylinder 101, a space in the double-acting pneumatic cylinder 101 being partitioned into a 1 st pressure acting chamber 103 and a 2 nd pressure acting chamber 104 by the piston 102 slidably held in the double-acting pneumatic cylinder 101, a piston rod 105 being connected to a 2 nd piston end surface 102b of the piston 102, the actuator operation detection device 20 comprising: a 1 st pressure detector 202 that detects the pressure of the 1 st pressure operation chamber 103; a 2 nd pressure detector 203 that detects the pressure of the 2 nd pressure operation chamber 104; a differential amplifier circuit 205 that calculates a thrust force F acting on the piston 102 from the pressure (1 st pressure value P1) detected by the 1 st pressure detector 202, the pressure (2 nd pressure value P2) detected by the 2 nd pressure detector 203, and the pressure receiving area of the piston 102; and a microcomputer 201 for confirming the operating state of the piston 102 based on the thrust force F. Thus, the 1 st pressure detector 202 and the 2 nd pressure detector 203 detect the pressure of the 1 st pressure operation chamber 103 and the pressure of the 2 nd pressure operation chamber 104, respectively, and the differential amplifier circuit 205 calculates the thrust force F acting on the piston 102 from the pressure of the 1 st pressure operation chamber 103, the pressure of the 2 nd pressure operation chamber 104, and the pressure receiving area of the piston 102. Then, the microcomputer 201 can confirm the operating state of the piston 102 based on the calculated thrust force F. The following relationships exist: the force acting on the 1 st piston end surface 102a of the piston 102 is larger than the force acting on the 2 nd piston end surface 102b during the forward movement of the piston 102, and the force acting on the 2 nd piston end surface 102b is larger than the force acting on the 1 st piston end surface 102a during the backward movement of the piston 102. Since this relationship does not change with the speed of the operation tempo, it becomes clear whether the piston 102 is moving forward or backward by calculating the thrust force F acting on the piston 102, and the operation of the piston 102 can be accurately monitored.

(2) In the actuator operation detection device 20 according to (1), the differential amplifier circuit 205 is configured to calculate the thrust force F in consideration of the fact that the pressure receiving area of the 2 nd piston end surface 102b of the piston 102 is smaller than the pressure receiving area of the 1 st piston end surface 102a of the piston 102 by the outer diameter of the piston rod 105, and the microcomputer 201 is configured to check the operation state of the piston 102 based on the sign of the thrust force F. Since the piston rod 105 is connected to the 2 nd piston end surface 102b of the piston 102, the thrust force F is calculated in consideration of the fact that the pressure receiving area of the 2 nd piston end surface 102b of the piston 102 is smaller than the pressure receiving area of the 1 st piston end surface 102a of the piston 102 by the outer diameter of the piston rod 105.

Here, the thrust force F is a value obtained by subtracting a product (the 3 rd pressure value P3) of the pressure of the 2 nd pressure operation chamber 104 (the 2 nd pressure value P2) and the pressure receiving area ratio from the pressure of the 1 st pressure operation chamber 103 (the 1 st pressure value P1).

The pressure receiving area ratio is a ratio of the pressure receiving area of the 2 nd piston end surface 102b of the piston 102 to the pressure receiving area of the 1 st piston end surface 102 a. For example, in the case where the diameter of the piston 102 is 25mm and the diameter of the piston rod 105 is 12mm, the ratio of the pressure receiving area of the 2 nd piston end surface 102b to the pressure receiving area of the 1 st piston end surface 102a of the piston 102 is about 0.75. That is, the value obtained by subtracting the product of the 2 nd pressure value P2 and 0.75 (the 3 rd pressure value P3) from the 1 st pressure value P1 becomes the thrust force F acting on the piston 102.

If the reciprocating motion of the piston 102 is monitored based on the pressure, when the piston 102 advances in a state where the displacement is controlled by the speed controller 14, the pressure receiving area of the 2 nd piston end surface 102b of the piston 102 becomes smaller by the connection area of the piston rod 105, and therefore, even in a state where the 2 nd pressure value P2 of the 2 nd pressure operation chamber 104 is higher than the 1 st pressure value P2 of the 1 st pressure operation chamber 103, the force acting on the 2 nd piston end surface 102b of the piston 102 can advance in a smaller amount than the force acting on the 1 st pressure operation chamber side end surface 102 a. Therefore, there may be a case where the reciprocating motion of the piston 102 cannot be accurately monitored based on the magnitude relationship between the 1 st pressure value and the 2 nd pressure value. On the other hand, by obtaining the thrust force F acting on the piston 102 in consideration of the pressure receiving area of the piston 102, the thrust force F is always a positive value when the piston 102 is moving forward, and the thrust force F is always a negative value when the piston 102 is moving backward.

Further, since the microcomputer 201 can confirm the operating state of the piston 102 based on the sign of the thrust force F, the microcomputer 201 can determine whether the piston 102 is moving forward or backward based on whether the thrust force F is a positive value or a negative value. Therefore, whether the piston 102 is moving forward or backward is clear, and therefore, the operation of the piston 102 can be accurately monitored.

(3) The actuator operation detection device 20 according to (1) or (2), wherein the microcomputer 201 is configured to check the operating state of the piston 102 based on the rate of change of the thrust force F. Thus, the microcomputer 201 only needs to perform information processing based on the rate of change of the thrust force F, and there is no need to perform information processing in parallel with the conventional technique on both the rate of change of the 1 st pressure value in the 1 st pressure operation chamber 103 and the rate of change of the 2 nd pressure value in the 2 nd pressure operation chamber 104, and therefore the possibility of delay in information processing of the microcomputer 201 built in the actuator motion detection device 20 is eliminated.

(4) The actuator motion detecting device 20 according to any one of (1) to (3), wherein the microcomputer 201 is configured to determine whether the piston 102 has started moving or stopped moving, and whether the piston 102 is moving toward the 1 st cylinder end face 101a of the double acting cylinder 101 (is performing a backward movement) or moving toward the 2 nd cylinder end face 101b of the double acting cylinder 101 (is performing an forward movement). Therefore, since the display unit 206 is provided in the actuator operation detection device 20, and the information determined by the microcomputer 201 can be displayed on the display unit 206, so that the user can grasp the exact operating state of the actuator 10, the operation of setting the operation tempo desired by the user while adjusting the pressure of the fluid to be fed, the speed controller 14, and the like can be easily performed.

The present embodiment is merely an example, and the present invention is not limited to the embodiment. Therefore, it is needless to say that various improvements and modifications can be made to the present invention without departing from the scope of the invention.

For example, although the present embodiment has been described with respect to the state in which the exhaust gas amount is limited by the speed controller 14, the same effects as those of the present embodiment can be obtained even in the state in which the intake air amount is controlled by the speed controller.

Description of the symbols

10 actuator

20 actuator operation detection device

101 double-acting pneumatic cylinder

102 piston

103 1 st pressure action chamber

104 2 nd pressure acting chamber

105 piston rod

201 micro computer

202 st pressure detector

203 nd 2 nd pressure detector

204 voltage divider

205 differential amplifier circuit