JPH09317705A - Actuator speed control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a speed control device for a hydraulic actuator with which precise operation speed can be finely set correspondingly to each step of displacement of a hydraulic actuator irrespective of a stroke amount of the hydraulic actuator, a device can be simplified, a cost is reduced and maintenance is facilitated. SOLUTION: A speed control device controls operation speed of a hydraulic cylinder correspondingly to displacement of the cylinder. In such a device, the displacement of the hydraulic cylinder is obtained by integrating a valve passing flow rate Q through a proportional solenoid valve 2 arranged between the hydraulic cylinder and a hydraulic source, and dividing the resultant operation oil supply amount by a speed flow rate conversion factor. The speed flow rate conversion factor is obtained through a pressure receiving area of the hydraulic cylinder, or a value prepared by dividing the operation oil supply amount when the hydraulic cylinder is at a full-stroke by the length of the full stroke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a speed control device that controls the operating speed of a hydraulic actuator in response to its displacement.

[0002]

2. Description of the Related Art As a speed control device for controlling an operating speed of an actuator according to a displacement amount of a hydraulic actuator, there is one using a limit switch as shown in FIG. 7, for example.

As shown in FIG. 7, a hydraulic cylinder 1 which is an actuator is supplied with hydraulic oil from a hydraulic pressure source 3 through a flow control valve 8 and expands and contracts a rod 4 at a speed according to the flow rate of the supplied hydraulic oil. Let The displacement of the hydraulic cylinder 1 (displacement of the rod 4) is detected by a plurality of limit switches 9 arranged at predetermined intervals, and this detection signal is input to the controller 7.

The controller 7 outputs a valve control signal to the flow rate control valve 8 in accordance with a flow rate command value preset corresponding to the displacement of the hydraulic cylinder 1 to adjust the valve opening degree of the flow rate control valve 8. Thus, the flow rate of the hydraulic oil supplied to the hydraulic cylinder 1 (that is, the operating speed of the hydraulic cylinder 1) is controlled.

Further, FIG. 8 uses a displacement sensor 10 instead of the limit switch 9 of FIG. 7, and the displacement of the hydraulic cylinder 1 is detected by the displacement sensor 10.
As in the case of FIG. 8, the hydraulic cylinder 1 accordingly follows.
The operating speed of is controlled.

[0006]

However, the conventional hydraulic actuator speed control device as shown in FIGS. 7 and 8 has the following disadvantages.

That is, as shown in FIG. 7, in the speed control device using the limit switches 9, the displacement of the hydraulic cylinder 1 is detected by each limit switch 9 at predetermined intervals where a plurality of limit switches 9 are arranged. To be done.

For this reason, if the speed control of the hydraulic cylinder 1 is to be divided into smaller sections, the total number of limit switches 9 arranged is increased to set the operating speed of the hydraulic cylinder 1 set for each limit switch 9. However, this not only causes the cost to increase, but also complicates the electric wiring and causes troublesome maintenance. Further, since the number of input ports for inputting the detection signal from each limit switch 9 to the controller 7 is limited in the first place, the total number of limit switches 9 cannot be increased beyond this limit.

On the other hand, in the speed control device using the displacement sensor 10 as shown in FIG. 8, fine control can be performed, but the stroke of the displacement sensor 10 is limited.
It cannot be applied to the hydraulic cylinder 1 having a large stroke length.

The present invention focuses on such a problem,
Regardless of the stroke of the hydraulic actuator, it is possible to precisely set the operating speed that corresponds to each stage of the displacement of the hydraulic actuator, simplify the device, reduce the cost, and make maintenance easy. An object is to provide a speed control device for an actuator.

[0011]

A first aspect of the present invention is directed to a hydraulic actuator which operates by receiving hydraulic oil from a hydraulic source, a proportional control valve interposed between the hydraulic actuator and the hydraulic source, In a speed control device for a hydraulic actuator, comprising: an operating speed control means for controlling an operating speed of a hydraulic actuator by adjusting a valve passing flow rate passing through a proportional control valve per unit time; The operating speed control includes: a passage flow rate detecting means; an actuator displacement calculating means for calculating the displacement of the hydraulic actuator from the valve passing flow rate; and a speed command setting means for setting a speed command pattern according to the displacement of the hydraulic actuator. The means is proportional so that the flow rate command value set corresponding to the actuator displacement and the actual flow rate through the valve match. To control the valve.

In the second invention, the actuator displacement is calculated as a value obtained by dividing the hydraulic oil supply amount to the hydraulic actuator obtained by integrating the valve passage flow rate by a predetermined velocity flow rate conversion coefficient.

In the third invention, the hydraulic actuator is a hydraulic cylinder that expands and contracts within a predetermined stroke,
The velocity flow rate conversion coefficient is the pressure receiving area.

In the fourth invention, the hydraulic actuator is a hydraulic cylinder that expands and contracts within a predetermined stroke.
A speed flow rate conversion coefficient calculating means for calculating the speed flow rate conversion coefficient as a value obtained by dividing the amount of hydraulic oil supplied to the hydraulic cylinder when the hydraulic cylinder makes a full stroke by the length of the full stroke is provided.

In the fifth invention, the hydraulic actuator is a hydraulic motor, and the velocity / flow rate conversion coefficient is displacement thereof.

[0016]

In the first aspect of the present invention, the displacement amount of the hydraulic actuator has a certain correlation with the supply flow rate (valve passage flow rate). Therefore, by using this correlation, the actuator is based on the valve passage flow rate. Is calculated. Therefore, by determining the stroke position of the hydraulic actuator based on the calculated displacement, regardless of the stroke length of the displacement of the hydraulic actuator, the precise operating speed can be set accurately corresponding to each stage of displacement over the entire stroke. It becomes possible to perform accurate speed control. Further, a device for measuring the displacement of the hydraulic actuator is not required, and electric wiring or the like for them is not required, so that the device can be simplified and cost reduction and maintenance can be facilitated.

In the second aspect of the invention, since the actuator displacement of the hydraulic actuator is easily calculated from the valve passing flow rate by using the velocity flow rate conversion coefficient, each stage of the displacement is finely handled over the entire stroke of the displacement of the hydraulic actuator. Accurate operating speed can be set, accurate speed control can be performed, and a device for measuring the displacement of the hydraulic actuator is not required, which simplifies the device and reduces cost and facilitates maintenance. Can be planned.

In the third aspect of the invention, since the pressure receiving area of the hydraulic cylinder becomes the velocity flow rate conversion coefficient, the displacement of the hydraulic cylinder can be easily calculated from the valve passing flow rate, and the displacement of each stage of the displacement of the hydraulic cylinder can be calculated over the entire stroke. It is possible to set the precise operating speed in a finely tuned manner, to perform accurate speed control, and to eliminate the need for a device for measuring the displacement of the hydraulic cylinder, simplifying the device and reducing costs and maintenance. Can be facilitated.

In the fourth aspect of the present invention, the speed-flow rate conversion coefficient is calculated based on the hydraulic oil supply amount at the full stroke of the actuator. As a result, an appropriate speed-flow rate conversion coefficient can be obtained without using the data on the shape of the actuator. Even if the calculation can be performed and the hydraulic oil is leaked, the speed-flow rate conversion coefficient can be calculated and updated accurately, so that the actuator displacement can be accurately calculated and the speed of the hydraulic actuator can be appropriately controlled. it can.

In the fifth aspect of the invention, since the displacement of the hydraulic motor becomes the velocity / flow rate conversion coefficient, the displacement of the hydraulic motor can be easily calculated from the valve passing flow rate, and the displacement of the hydraulic motor can be precisely adjusted in each stage. The operating speed can be set, precise speed control can be performed, and a device for measuring the displacement of the hydraulic motor is not required, which simplifies the device and reduces costs and facilitates maintenance. obtain.

[0021]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

As shown in FIG. 1, the hydraulic cylinder 1 which is a hydraulic actuator operates by receiving the supply of hydraulic oil from a hydraulic pressure source 3 via a proportional electromagnetic flow control valve 2.

A pair of limit switches 5 and 6 are provided on the rod 4 side of the hydraulic cylinder 1 at a predetermined interval S. These limit switches 5 and 6 are used for the hydraulic cylinder 1.
When the displacement of the hydraulic cylinder 1 reaches the lower end of the stroke, a signal LS from the limit switch 5 on the lower end of the stroke is detected.
When A reaches the upper end of the stroke, the signal LSB from the limit switch 6 on the upper end side of the stroke is input to the controller 7, and the controller 7 stops the operation of the hydraulic cylinder 1.

The activation of the hydraulic cylinder 1 is performed by a start switch signal RU input to the controller 7 by the operator.
The hydraulic cylinder 1 at the lower end of the stroke is driven toward the upper end of the stroke, and the hydraulic cylinder 1 at the upper end of the stroke is driven toward the lower end of the stroke to reach the upper end or the lower end of the stroke and stop.

The proportional solenoid control valve 2 includes a displacement sensor 11 for detecting the valve displacement X, and pressures (P and P) at two ports (A port and B port) on the upstream side and the downstream side of the proportional solenoid control valve 2.
A and PB) for detecting a pair of pressure sensors 12, 13
Are built in, and the detection signals (valve displacement X, A port pressure PA, B port pressure PB) from these sensors are input into the controller 7.

Based on these detected values, the controller 7 calculates a valve passage flow rate Q which is a flow rate of the hydraulic oil passing through the proportional electromagnetic control valve 2 per unit time, as will be described later, and from this, the hydraulic cylinder 1 Calculate displacement. Further, the controller 7 outputs a valve control signal SIG to the proportional electromagnetic control valve 2 so that the flow rate command value QR set in advance corresponding to the displacement of the hydraulic cylinder 1 and the actual valve passing flow rate Q match. By doing so, the valve displacement X of the proportional electromagnetic control valve 2 is controlled, and finally the operating speed of the hydraulic cylinder 1 proportional to the valve passage flow rate Q is controlled.

The measurement of the valve passing flow rate Q is not limited to such a calculating means, and may be directly measured by using, for example, a flow rate sensor.

FIG. 2 shows the internal structure of the controller 7 in detail.

The valve passage flow rate calculation circuit 21 calculates the valve passage flow rate Q.
Is a circuit for calculating the valve displacement X from the displacement sensor 11.
Opening area A of the proportional solenoid control valve 2 calculated as a function of
And the valve differential pressure P = PA-PB calculated from the detection signals PA and PB from the pressure sensors 11 and 12, the valve passage flow rate Q is Q = CA · (2│P│ / ρ) 1/2 ... (1) is calculated. However, C is a flow coefficient and ρ is hydraulic oil density.

In the actuator displacement calculating circuit 22, the actuator displacement Y is calculated as Y = (1 / D) Qdt ... (2) based on the valve passing flow rate Q.

Here, D is a velocity flow rate conversion coefficient that is set and input according to the specifications of the actuator. In the case of the hydraulic cylinder 1 as in the present embodiment, the hydraulic cylinder 1
Is the pressure receiving area. A hydraulic motor may be provided instead of the hydraulic cylinder 1 to control the relationship between the rotation amount and the rotation speed. In this case, the displacement volume corresponds to the velocity flow rate conversion coefficient D.

Further, since the actuator displacement Y is reset by switching the start switch signal RUN, the integration of the equation (2) is performed from the time of this reset, and the upper end of the stroke of the hydraulic cylinder 1 or the stroke. As a result of starting the integration from the stopped state of the lower end, the movement displacement from the stop position (the upper stroke end or the lower stroke end) is calculated as the actuator displacement Y.

The flow rate command value calculation circuit 23 uses the flow rate command value QR
As shown in detail in FIG. 3, the speed command value determining circuit 31 provided therein determines the speed command value VR based on the speed command pattern table 25 and the actuator displacement Y. . This speed command value V
The flow rate command value QR is calculated by multiplying R by the velocity flow rate conversion coefficient D.

The speed command pattern table 25 is
7 is a diagram defining a speed command value VR of the operating speed of the hydraulic cylinder with respect to the displacement of the hydraulic cylinder 1.
It is stored in advance.

Further, the flow rate command value calculation circuit 23 includes a stop determination circuit 32 which determines whether or not the hydraulic cylinder 1 has reached the stop position from the start switch signal RUN and the limit switch signals LSA and LSB. As a result, if it is determined that the hydraulic cylinder 1 has reached the stop position, the flow rate command value QR is switched to zero and the proportional electromagnetic control valve 2 is fully closed.

The control compensation calculation circuit 25 is a circuit that operates the valve control signal SIG so that the valve passage flow rate Q and the flow rate command value QR match. This control method is, for example, PID compensation or phase lead / lag compensation, but is not limited to these.

Next, the operation will be described.

In order to operate the hydraulic cylinder 1, a start switch signal RUN is externally input to the controller 7. As a result, the hydraulic cylinder 1 located on the lower end side of the stroke (the limit switch 5 side) is activated and its rod 4
Extend to the upper end of the stroke (the limit switch 6 side).

At this time, the controller 7 calculates the amount of hydraulic oil supplied to the hydraulic cylinder 1 by integrating the valve passage flow rate Q of the proportional electromagnetic control valve 2, and then calculates the displacement of the hydraulic cylinder 1. In order to obtain the operating speed of the hydraulic cylinder 1 corresponding to the displacement of the hydraulic cylinder 1,
The controller 7 outputs a valve control signal SIG to control the valve displacement X of the proportional electromagnetic control valve 2.

As described above, according to the present invention, it is not necessary to dispose a limit switch or a displacement sensor in the expansion / contraction process of the rod 4 in order to measure the displacement of the hydraulic cylinder 1, and the cost for these can be reduced. The device can be simplified without increasing the number of electric wirings and the maintenance can be easily performed.

Further, since the displacement of the hydraulic cylinder 1 can be continuously detected in the entire width of the expansion and contraction stroke of the rod 4, the displacement of the hydraulic cylinder 1 can be finely adjusted regardless of the stroke length of the hydraulic cylinder 1. It is possible to precisely control the operating speed.

FIG. 4 shows another embodiment of the present invention.

In this embodiment, the controller 7 of FIG.
Is provided with a velocity flow rate conversion coefficient calculation circuit 26. The speed / flow rate conversion coefficient calculation circuit 26 calculates the speed / flow rate conversion coefficient D.
Is a circuit for automatically calculating, and therefore, in order to set the velocity flow rate conversion coefficient D, it is necessary to know detailed information of the actuator, and there is internal leakage of hydraulic oil in the hydraulic cylinder 1. In this case, the inconvenience that the set velocity flow rate conversion coefficient D is not appropriate is eliminated.

The speed / flow rate conversion coefficient calculation circuit 26 calculates the distance S between the limit switches 5 and 6 (the length of the full stroke of the hydraulic cylinder 1) and the displacement S between the limit switches 5 and 6 of the hydraulic cylinder 1. (That is, calculated by the valve passage flow rate calculation circuit 21 during the operation of the hydraulic cylinder 1), the speed is calculated by using the integral value IQ of the valve passage flow rate Q (when the hydraulic cylinder 1 makes a full stroke). The flow rate conversion coefficient D is calculated by D = IQ / S (3), and this value is updated every time the hydraulic cylinder 1 is stopped. As a result, the appropriate velocity flow rate conversion coefficient D
Can be set, and the characteristics of the speed control according to the present invention are improved.

5 and 6 show still another embodiment of the present invention, in which the present invention is applied to an actuator (double-acting cylinder 41) capable of reciprocating operation.

In this case, in order to selectively supply the working oil to the oil chambers 42 and 43 on both the expansion side and the contraction side of the double-acting cylinder 41, in FIG. A switching valve 44 is arranged on the cylinder 41 side. Further, in FIG. 6, the switching valve 44 is arranged closer to the hydraulic pressure source 3 than the proportional electromagnetic control valve 2A on the expansion side and the proportional electromagnetic control valve 2B on the contraction side.

As a result, the oil chambers 42, 43 have the switching valve 4
4 is selectively connected to the hydraulic power source 3 or the tank 45, and the proportional electromagnetic control valve 2 or 2A, 2B is controlled by the controller 7, so that the expansion direction or the contraction direction is different from that in FIG. Similarly, the speed of the double-acting cylinder 41 which is displaced between the limit switches 5 and 6 can be controlled.

[0048]

According to the first aspect of the present invention, the displacement amount of the hydraulic actuator has a certain correlation with the supply flow rate (valve passage flow rate). Based on this, the displacement of the actuator is calculated.
Therefore, by determining the stroke position of the hydraulic actuator based on the calculated displacement, regardless of the stroke length of the displacement of the hydraulic actuator, the precise operating speed can be set accurately corresponding to each stage of displacement over the entire stroke. It becomes possible to perform accurate speed control. Further, a device for measuring the displacement of the hydraulic actuator is not required, and electric wiring or the like for them is not required, so that the device can be simplified and cost reduction and maintenance can be facilitated.

According to the second aspect of the present invention, the actuator displacement of the hydraulic actuator is easily calculated from the valve passing flow rate by using the velocity flow rate conversion coefficient. It is possible to set an appropriate operating speed correspondingly, to perform accurate speed control, and to eliminate the need for a device for measuring the displacement of the hydraulic actuator, simplifying the device and reducing costs and maintenance. It can be facilitated.

According to the third invention, since the pressure receiving area of the hydraulic cylinder becomes the velocity flow rate conversion coefficient, the displacement of the hydraulic cylinder can be easily calculated from the valve passing flow rate, and the displacement of each of the displacements of the hydraulic cylinder can be calculated over the entire stroke. It is possible to set an accurate operating speed that corresponds to each stage in detail, it is possible to perform accurate speed control, and a device for measuring the displacement of the hydraulic cylinder is not required, which simplifies the device.
It is possible to reduce costs and facilitate maintenance.

According to the fourth invention, as a result of being calculated on the basis of the hydraulic oil supply amount at the full stroke of the actuator, an appropriate velocity flow rate conversion coefficient can be calculated without depending on the data on the shape of the actuator, and Even if the hydraulic oil leaks or the like, the velocity-flow rate conversion coefficient can be accurately calculated and updated, so that the actuator displacement can be accurately calculated and the speed of the hydraulic actuator can be appropriately controlled.

According to the fifth aspect of the invention, since the displacement of the hydraulic motor becomes the velocity flow rate conversion coefficient, the displacement of the hydraulic motor can be easily calculated from the valve passing flow rate, and the displacement of the hydraulic motor can be finely adjusted. Accurate operating speed can be set, accurate speed control can be performed, and a device for measuring the displacement of the hydraulic motor is not required, which simplifies the device and reduces cost and facilitates maintenance. Can be planned.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram similarly.

FIG. 3 is a configuration diagram of the same.

FIG. 4 is a configuration diagram showing another embodiment of the present invention.

FIG. 5 is a configuration diagram showing still another embodiment of the present invention.

FIG. 6 is a configuration diagram showing still another embodiment of the present invention.

FIG. 7 is a configuration diagram showing a conventional speed control device.

FIG. 8 is a configuration diagram of the same.

[Explanation of symbols]

 1 Hydraulic Cylinder 2 Proportional Electromagnetic Control Valve 3 Hydraulic Source 7 Controller 11 Displacement Sensor 12 Pressure Sensor 13 Pressure Sensor 21 Valve Passage Flow Rate Calculation Circuit 22 Actuator Displacement Calculation Circuit 23 Flow Rate Command Value Calculation Circuit 24 Speed Command Pattern Table 25 Control Compensation Calculation Circuit 26 Velocity flow rate conversion coefficient calculation circuit

Claims (5)

[Claims] Claim: What is claimed is: 1. A hydraulic actuator which operates by receiving hydraulic oil from a hydraulic source, a proportional control valve interposed between the hydraulic actuator and the hydraulic source, and the proportional control valve which is passed per unit time. An operating speed control means for controlling an operating speed of a hydraulic actuator by adjusting a valve passing flow rate, and a valve passing flow rate detecting means for detecting the valve passing flow rate, comprising: An actuator displacement calculation means for calculating the displacement of the hydraulic actuator from the flow rate, and a speed command setting means for setting a speed command pattern according to the displacement of the hydraulic actuator are provided, and the operating speed control means corresponds to the actuator displacement. The proportional control valve is controlled so that the set flow rate command value and the actual flow rate through the valve match. A speed control device for hydraulic actuators. 2. The actuator displacement is calculated as a value obtained by dividing a hydraulic oil supply amount to the hydraulic actuator obtained by integrating the valve passage flow rate by a predetermined velocity flow rate conversion coefficient. 1. A speed control device for a hydraulic actuator according to 1. 3. The speed control device for a hydraulic actuator according to claim 2, wherein the hydraulic actuator is a hydraulic cylinder that expands and contracts within a predetermined stroke, and the speed / flow rate conversion coefficient is a pressure receiving area thereof. 4. The hydraulic actuator is a hydraulic cylinder that expands and contracts within a predetermined stroke, and the speed / flow rate conversion coefficient is the hydraulic oil supply amount to the hydraulic cylinder when the hydraulic cylinder makes a full stroke. 3. The speed control device for a hydraulic actuator according to claim 2, further comprising speed flow rate conversion coefficient calculation means for calculating as a value divided by. 5. The speed control device for a hydraulic actuator according to claim 2, wherein the hydraulic actuator is a hydraulic motor, and the speed / flow rate conversion coefficient is a displacement thereof.