JPH0668703B2 - Automatic setting constant flow valve - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a valve for controlling the amount of fluid flowing in a pipe, and more particularly to a constant flow valve used for maintaining a constant flow rate regardless of pressure fluctuations.

<Prior Art> In general, a constant flow valve grasps the pressure difference between before and after the valve, and adjusts the opening and closing of the valve to a set flow rate, thereby self-adjusting the fluid flow through the valve.

When the flow rate is set to a desired value, various kinds of forces of springs that urge the valve seat and the valve element are selected to obtain a valve through which the desired flow rate flows. Therefore, it is extremely inconvenient to change the set flow rate frequently. Also, remote control and automatic control are not possible.

Therefore, conventionally, in such a case, an automatic control valve is used. An automatic control valve controls the operation part such as an electric motor or a fluid actuator that operates a valve body by detecting a control amount of a controlled object, comparing it with a target value, judging based on a deviation, and processing a command in a signal manner. Is.

When used as a constant flow valve, a flow meter that outputs an electrical signal detects the flow rate in the pipe, compares it with the target value input through the setting mechanism, and processes it signalically to drive it through an actuator such as an electric motor. , Proportional, differential, integral operation, so-called PID control.

<Problems to be Solved by the Invention> However, when the above-mentioned PID control is performed, it is difficult to determine the constants of P, I, and D for determining the manipulated variable of the valve. Is required. Further, in this control method, since the valve is operated while comparing the two so that the actually measured value approaches the target value, the responsiveness is very poor, and it takes time to reach the set flow rate or goes too far. This is because it is not the flow rate that is being controlled, but the flow rate is controlled as a result of adjusting the opening of the valve, so there is no linear relationship between the operation amount given to the valve by the operation unit such as an actuator and the flow rate, This is because the control becomes complicated.

Moreover, the automatic control valve is expensive. This is because it is necessary to operate the valve body directly and constantly in small steps quickly with an actuator such as an electric motor, so that a high output actuator and a control device for performing complicated signal processing are required.

Therefore, a technical problem of the present invention is to provide an automatic setting constant flow valve which can be remotely operated and automatically controlled to easily change the set flow rate, has a simple control method, has a quick response, and is inexpensive. It is in.

<Means for Solving the Problem> The technical means of the present invention taken to solve the above-mentioned problems is a valve casing having an inlet and an outlet, and a conical valve body that is temporarily expanded to the outlet side. An annular valve seat that surrounds the valve body and slides in the flow direction of the fluid is arranged in the valve casing, one end of which is fixed in the valve casing and the other end of which is provided to urge the valve seat toward the inlet direction. In a self-adjusting constant flow valve equipped with a spring, a drive means for changing the position of the means for changing the position of the valve body is attached to the valve casing,
By storing the relationship between the set flow rate and the displacement amount of the valve body in a controller equipped with setting input means and inputting a desired set flow rate from the setting input means, the controller calculates the optimum valve body position. The driving means is driven by the calculated adjustment amount.

<Operation> The operation of the above technical means is as follows.

Generally, the amount of fluid passing through a valve is determined by the valve opening area (fluid passage area) of the valve and the differential pressure before and after that, and in this case as well, an arbitrary differential pressure before and after the constant flow valve. When the fluid flows due to the fluid, the fluid displaces the valve seat in the direction of the outlet against the biasing force of the spring due to the flow resistance, and stops at the point where the fluid balances with the spring force. Then, at this time, a certain fluid passes through the valve opening area formed between the valve seat and the valve body.

Next, if the pressure on the inlet side of the valve increases and the differential pressure across the valve increases, the flow rate that passes through the valve opening will increase, but due to the increase in flow resistance due to the increase in flow rate, the valve seat will also increase. Furthermore, it is displaced toward the exit side. If the valve seat is displaced, the distance from the conical valve body becomes shorter and the valve opening area becomes smaller.
Therefore, even if the differential pressure increases, the valve opening area decreases accordingly, so that the flow rate does not increase and remains constant.

To change the set flow rate, if the displacement of the valve body or the spring force that urges the valve seat is changed, the distance between the valve seat and the valve body changes, and the flow rate can be changed even with the same pressure difference. Therefore, if the relationship between the adjustment amount (position) of the valve body and the set flow rate is stored in the storage device in the controller and the desired set flow rate is input from the setting input means, the above relationship is calculated by the arithmetic unit in the controller. From this, the optimum adjustment amount of the valve body is calculated. A control signal based on the calculated adjustment amount is sent to the drive unit for operation, and the valve body moves to a desired value and stops. In order to move and stop the driving means by the calculated adjustment amount, a position detecting means such as a potentiometer is used. However, the stepping motor controls the position of the valve body or the operating shaft of the driving means itself.

<Effects of the Invention> The present invention produces the following unique effects.

The automatic setting constant flow valve of the present invention does not need to determine the constants of P, I, and D, so that the control is simple and, moreover, the valve opening is controlled via the drive unit while comparing the target value and the measured value. Since it is not a control method to operate, the required amount of drive is operated all at once toward the target value, the valve is mechanically operated quickly as in the past, quick response control is possible, and the set flow rate can be easily changed. be able to.

Further, when the initial setting is completed, the drive unit has no operating machine until the next set pressure is changed, and its operating time is short, so that it has a longer life than the automatic control valve.

<Example> An example showing a specific example of the above technical means will be described.
(See FIG. 1) This embodiment comprises a constant flow valve section 2 and a drive section 4. A cylindrical valve chamber 12 is provided in a main body 10 that forms an inlet 6 and an outlet 8, and a cylindrical valve seat 14 is slidably accommodated between the protrusion 18 and the valve seat 14 at the rear of the valve chamber 12. The spring 20 is arranged and the valve seat 1
4 is always urged toward the entrance side. Then, it is locked by the ring 16 so as to regulate its movement.

A bellows chamber 22 is provided in the upper portion of the main body 10, and a bellows 24 is housed in the bellows chamber 22. The lower end surface of the bellows 24 is formed integrally with the conical valve body 26, and its valve shaft 28 slides while being guided by the bearing 30, so that the valve body 26 moves in the fluid flow direction in the valve chamber 12. It is displaced as the bellows 24 expands and contracts. The bellows 24 is always urged upward by a spring 34 interposed between the bellows 24 below the bellows 24.

On the other hand, the flange 36 of the drive unit 4 and the upper flange portion of the bellows chamber 22 are attached by bolts with the heat insulating material 38, the female screw member 40, and the flange 42 of the bellows 24 sandwiched therebetween. The drive unit 4 includes a motor 44, a potentiometer 46, and a speed reducer 4.
8 and electronic components for driving the motor (not shown).

The output shaft 50 of the speed reducer 48 is spline-connected with the adjusting screw 56. The spline fitting portion 52 is provided with rollers 54a and 54b on a roller shaft that penetrates the output shaft 50 in the radial direction.
On the other hand, the upper portion of the adjusting screw 56 is formed into a cylindrical shape, grooves 56a and b are formed in the cylindrical portion in the axial direction, and the rollers 54a and 54b are fitted into the grooves. Further, the adjusting screw 56 and the female screw member 40 are screwed together. Therefore, output shaft 5
When 0 rotates to the left and right, rollers 54a, b and grooves 56a,
b meshes with each other and transmits the rotation to the adjusting screw 56. The adjustment screw 56 is axially displaced by the screw connection with the female screw member 40, and the displacement is slid in the grooves 56a and 56b. The member numbers 58 and 60 are frust bearings. The lower end of the adjusting screw 56 is brought into contact with the inner lower end of the bellows 24, and the displacement thereof is transmitted to the valve body 26.

The operation of the constant flow valve unit 2 is as follows. When the fluid is flowing at an arbitrary differential pressure with an inlet and an outlet, the valve seat 14 is displaced to the position shown in FIG. 1 by the flow resistance,
At that time, the flow rate is determined by the opening area according to the distance X from the valve body 26. Next, if the inlet pressure rises and the differential pressure before and after the valve mouth increases, the flow rate tends to increase, but the flow rate resistance also increases and the valve seat 14 is further displaced. When the valve seat 14 is displaced, the valve body 26 has a conical shape, so that the distance Y becomes smaller,
That is, the opening area is also reduced, and as a result, even if the differential pressure increases, the flow rate does not increase and is kept constant.

Here, when it is desired to change the set flow rate, the valve body 26 can be moved to adjust the distance from the valve seat 14 and the opening area can be arbitrarily changed. Therefore, the relationship between the displacement of the valve body 26 and the set flow rate can be determined by an experiment. Can be found at.

A computer in the controller 62 stores the relationship between the set flow rate and the adjustment amount (position) of the valve body 26. Therefore, if the set flow rate is input from the setting input device 64, the adjustment amount of the valve body 26 is calculated from the relationship stored in the controller 62, and the motor 44 is driven by the control signal based on the calculated adjustment amount. The adjusting screw moves the valve body 26 via the bellows 24. The displacement of the adjusting screw 56 is detected by the potentiometer 46, and if this signal matches the calculated control signal, the motor 44 stops. Thus, by simply inputting an arbitrary set flow rate, it is possible to easily flow a constant flow rate of fluid without complicated control.

If more precise control is required, the flow rate in the pipe is detected by a flow meter that can be electrically output, and if there is a deviation by constantly comparing it with the target value, it is equivalent to the pressure difference from the above relationship. The correction amount can be re-calculated by recalculating the adjustment amount of the valve body to be operated.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the automatic setting constant flow valve of the present invention. 2: Constant flow rate valve part, 4: Driving part 6: Inlet, 8: Outlet 14: Valve seat, 24: Bellows 26: Valve body, 44: Motor 62: Controller, 64: Setting input device

Claims (1)

[Claims] 1. In a valve casing forming an inlet and an outlet,
There is a conical valve element that spreads to the outlet side for a while, and an annular valve seat that surrounds the valve element and slides in the fluid flow direction inside the valve casing.One end is fixed in the valve casing and the other end is the valve. In a self-adjusting constant flow valve equipped with a spring that biases the seat toward the inlet, a drive means for changing the position of the means for changing the position of the valve body is attached to the valve casing to set the flow rate. And the amount of displacement of the valve disc is stored in a controller equipped with setting input means, and if a desired set flow rate is input from the setting input device, the optimal valve disc position is calculated by the controller, An automatically set constant flow valve which drives the drive means by the calculated adjustment amount.