JPH0650444A - Flow rate control device - Google Patents

Abstract

PURPOSE:To improve he stability and the responsiveness of the flow rate feedback control by a flow rate sensor and a DC motor in a flow rate control device to execute the opening/closing control and the flow rate adjustment of the fluid. CONSTITUTION:Two valve bodies 22, 24 connected to one valve shaft 6 are provided in a passage having two inlets 18, 19 and one outlet 20, and two valve elements 22, 24 are closed at the center position of the valve shaft 6, and either of the valve elements 22, 24 is selectively opened due to the movement of the valve shaft 6 from the center position, and a flow rate control device consists of a gain switching part 30 which independently switches the gain respectively in the opening and closing direction corresponding to two valve elements 22, 24 and a feedback control part 15 which receives the signal from the gain switching part and controls a motor 12 to open/close the valve so as to keep the flow rate at the preset value. Separate setting of gains of the valve elements 22, 24 in the opening and closing direction absorbs the changes in the torque of the valve shaft 6 due to the spring force, the hydrostatic force or the like and keeps the control characteristics to constant values, and the responsive speed can be improved without damaging the stability of the flow control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate control device for keeping hot water and water out of a bathroom, washbasin, kitchen, etc., and for obtaining a desired flow rate.

[0002]

2. Description of the Related Art Conventionally, a flow rate control device of this type is shown in FIG.
There was something like that.

A valve seat 4 is provided on the body 1 between a flow passage inlet 2 and a flow passage outlet 3, and a valve shaft 6 and a valve body 5 which are loosely fitted and connected to a valve body 5 facing the valve seat. A spring 7 for urging is provided. The thread portion 8 of the valve shaft 6 is screwed into the rotation straight line conversion screw 9 of the body 1. Further, the valve shaft 6 is a gear 10
And a DC motor 12 that is rotationally driven via a gear 11.
Is combined with. The DC motor 12 is controlled by the flow rate sensor 13, the flow rate calculation unit 14, and the feedback control unit 15 according to the difference between the flow rate signal from the flow rate calculation unit 14 and the set flow rate. Reference numeral 16 denotes a cam integrated with the gear 11, which is a motor 1
It has two position detectors 17.

FIG. 5 shows the characteristics of the feedback control unit 15. The motor 12 is driven by a voltage proportional to the flow rate error which is the difference between the flow rate signal and the set flow rate, and the valve shaft 6 is moved left and right to open the valve body 5. Alternatively, when the flow rate signal is adjusted to the close direction and the flow rate signal substantially matches the set flow rate, the DC motor 12 is stopped and the flow rate is adjusted to be equal to the set flow rate. In the range where the flow rate error in Fig. A is small, the voltage is proportional to the error,
In the range of flow rate error above a certain level in FIG.
Since there is a limit to the voltage applied to the motor, the motor voltage becomes constant.

[0005]

However, the conventional structure as described above has the following problems.

In the above structure, the force of the spring 7 is applied to the valve body 5 in the direction of closing the valve body 5, and the water pressure applied to the inlet 2 of the flow passage is also applied in the direction of closing the valve body 5. Therefore, the torque for moving the valve shaft 6 is large when the valve body 5 is opened and is small when the valve body 5 is closed. When the voltage for driving the DC motor 12 is controlled so as to have the same voltage absolute value with respect to the same flow rate error in the opening and closing directions as shown in FIG. The direction will move fast.

FIG. 6 shows the change characteristics of the flow rate when the set flow rate is increased or decreased as shown in FIG. C, and when the set flow rate is increased, the speed of the DC motor 12 becomes slower, so that the response as shown in FIG. On the contrary, when the set flow rate is decreased, the set flow rate is too fast, resulting in an oscillating response as shown in FIG. Therefore, when quick response is required for opening and closing the outlet of hot water or water and adjusting the flow rate, increasing the gain of the feedback control unit to move the DC motor 12 faster will cause an oscillating vibration when reducing the flow rate. There was a limit to how fast it became responsive.

The present invention is intended to solve the above problems and to realize a flow rate control device having good operability by improving the stability when the flow rate is decreased and the overall responsiveness.

[0009]

In order to achieve the above object, the present invention is provided with a feedback control section for switching the gain for each opening and closing directions of the valve body.

[0010]

With this structure, the gain is increased in the opening direction with a large torque to increase the voltage applied to the motor to increase the speed, while the gain is decreased in the closing direction with a small torque to decrease the voltage applied to the motor. Acts to stabilize the operation.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, the first inlet 18 into which hot water flows
A second inlet 19 through which water flows and one outlet 20,
Between the first inlet 18 and the outlet 20, the first valve seat 21 and the first
And a second valve seat 23 and a second valve body 24 are provided in the flow path body 1 between the second inlet 19 and the outlet 20, respectively. The first valve body 22 and the second valve body 24 are respectively provided with a first spring 25 and a second spring 26 that bias in the closing direction, and the valve shaft 6 is the second valve body 24.
Is slidably passed through, and its tip is slidably connected to the hole 27 of the first valve body 22, and further abuts on the second valve body 24 by a retaining ring 28. An O-ring 29 is provided in the penetrating portion between the second valve body 24 and the valve shaft 6 to seal the sliding portion. A flow rate sensor 13 is provided at the outlet 20, and a signal of the flow rate sensor 13 has its period measured by a flow rate calculation unit 14 to calculate a flow rate signal. This flow rate signal is compared with the set flow rate signal, and the feedback control unit 1 to which the deviation signal is input
A DC motor 12 drives a DC motor 12 to rotate a valve shaft 6 by a gear 11 and a gear 10, and a valve shaft 6 is driven in a thrust direction by a screw portion 8 of the valve shaft 6 and a rotation straight conversion screw 9. Gear 11
The cam 16 and the position detector 17 are provided on the valve shaft 6
Detect the center position of. A tap / stop switch 31 and a tap / stop switch 32 are connected to the gain switching unit 30, and the gain switching unit 30 switches the gain of the feedback control unit 15.

With the above structure, when the valve shaft 6 is at the center position, both the first and second valve bodies 22 and 24 are in contact with the first valve seat 21 and the second valve seat 23, respectively, and the outlet 20 There is no mixed water flowing in.

FIG. 2 shows the characteristics of flow rate error versus motor voltage in this embodiment. When the hot water supply / stop switch 31 is operated, the gain switching unit 31 selects the gain characteristic shown in FIG. 7C, and the feedback control unit 15 drives the DC motor 12 to move the valve shaft 6 to the left. While the second valve body 24 is in contact with the second valve seat 23, the valve shaft 6 slides on the O-ring 29 to oppose the force of the first spring 25 and the hydraulic force of the first inlet 18. The first valve body 22 is opened to supply hot water to the outlet 20. The flow rate sensor 13 generates a pulse signal having a frequency proportional to the flow rate, the flow rate calculation unit 14 calculates the flow rate, and the feedback control unit 15 controls the flow rate to be equal to the set flow rate. When the flow rate exceeds the set flow rate, the polarity of the flow rate error changes in response to the signal, and the gain switching unit 31 selects the gain of D in FIG.
Is driven to the right to keep the flow rate constant. At this time, the force of the first spring 25 and the force of water pressure push the first valve body 22 to the right, so the rotational torque of the valve shaft becomes extremely smaller than when the valve is opened. Therefore, the gain (slope) of D is set smaller than the gain of C. That is, by changing the gain according to the magnitude of the torque in the opening direction and the closing direction of the valve, the speed of the DC motor 12 is set to be the same for the same flow rate error.

FIG. 3 is a flow rate response characteristic when the set flow rate is increased or decreased as shown in FIG. G, and the response H when the set flow rate is increased can be made faster than the response D of the conventional example. The response when the set flow rate is reduced becomes stable by suppressing vibration as shown in FIG.

On the other hand, when the water discharge / stop switch 32 is operated, the valve shaft 6 is driven to the right, the first valve body 22 abuts on the first valve seat 21, and the valve shaft 6 has a hole 27. The slide ring 28 pushes the second valve body 24 open to the right by the stop ring 28,
The water at the inlet 19 is supplied to the outlet 20. At this time, the force of the second spring 26 and the hydraulic force of the second inlet 19 act in the same manner as described above. E in the wavy line in FIG. 2 is a gain characteristic when the second valve body is opened, and F in the same figure is a gain characteristic when the second valve body is closed. Since the sliding direction of the valve shaft 6 is opposite to the above, the motor voltage polarity is opposite to that in the case of the solid line in the figure. Further, when the second valve body 24 is driven to the right, there is no sliding of the valve shaft 6 and the O-ring 29, and therefore the torque is smaller than when the first valve body 22 is driven. The gain is smaller than the gain in Figure C,
Further, the gain of F in the figure is set smaller than the gain of D in the figure.

According to this embodiment, the feedback controller 15 sets independent gains C, E, D and F in the opening and closing directions of the first and second valve bodies 22 and 24, respectively. By absorbing the force due to the springs 25 and 26, the force due to the water pressure, and the torque change of the valve shaft 6 due to the sliding friction of the O-ring 29, in any case, the relationship between the flow rate error and the speed of the DC motor 12 is made constant. It is possible,
The same flow response characteristic can be obtained and the overall response speed can be increased.

[0018]

As described above, according to the flow rate control device of the present invention, the valve element and the spring for biasing the valve element, the motor for driving the valve shaft, the flow rate sensor, the opening and closing of the valve element, and Since it is configured with a feedback control unit that switches the gain depending on the closing direction, it absorbs the change in the valve shaft torque in the opening and closing directions due to the force of the spring, the force of water pressure, etc. Since it acts so as to maintain the same response characteristics in both the open and closed directions, the overall response speed can be increased while maintaining stable operation.

Further, in a flow path having two inlets and one outlet, two valve bodies connected to one valve shaft are provided, and the two valve bodies are closed at the center position of the valve shaft. By selecting one of the two valve bodies to open by the movement from the center position of the shaft, the feedback control unit independently switches the gain in the opening and closing directions corresponding to the two valve bodies. The difference in the torque of the valve shaft when driving the valve body is absorbed to act to make the relationship of the motor speed to the flow rate error constant, and the same flow response speed can be obtained in each opening and closing direction of each valve body. The selective opening / closing and flow rate adjustment of two fluids can be realized with good stability and operability at low cost.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a flow rate control device according to an embodiment of the present invention.

FIG. 2 is a gain characteristic diagram of feedback control of the device.

FIG. 3 is a flow response characteristic diagram of the device.

FIG. 4 is a block diagram of a conventional flow control device.

FIG. 5 is a gain characteristic diagram of conventional feedback control.

FIG. 6 is a conventional flow response characteristic diagram.

[Description of Reference Signs] 6 valve shaft 12 DC motor 13 flow rate sensor 15 feedback control unit 18 first inlet 19 second inlet 20 outlet 21 first valve seat 22 first valve body 23 second valve seat 24 second 2 valve body 25 1st spring 26 2nd spring 30 Gain switching part

Claims (3)

[Claims] 1. A flow passage body having an inlet and an outlet, a valve seat and a valve body provided in the flow passage body, a valve shaft connected to the valve body, and a biasing force of the valve body in a closing direction. A spring, a motor that drives the valve shaft to open and close the valve element, a flow rate sensor provided in the flow path of the outlet, and controls the motor according to the difference between the signal of the flow rate sensor and the signal of the set flow rate. A flow rate control device including a feedback control unit that switches the gain depending on the opening and closing directions of the valve body. 2. The gain is increased when the valve body is opened,
The flow rate control device according to claim 1, further comprising a feedback control unit that reduces a gain in the closing direction. 3. A flow path body having two inlets and one outlet, two sets of valve seats and valve bodies facing each other corresponding to the two inlets, and the two valve bodies being valved by one valve shaft. The two valve bodies are closed at the center position of the shaft, the valve shaft connected so as to open the two valve bodies independently by the movement from the center position, and the spring for urging the valve body in the closing direction. A flow rate sensor provided in a flow path that merges with one outlet downstream of one valve body,
While controlling the motor that drives the valve shaft to open and close the valve according to the difference between the signal of the flow sensor and the signal of the set flow rate,
A flow rate control device comprising a feedback control unit for independently switching the gains in the opening and closing directions corresponding to the two valve bodies.