JPH01103715A - Control valve device - Google Patents

Abstract

PURPOSE:To prevent hunting and to improve the responsiveness by providing a controller with plural characteristics indicating relations between the manipulated variable of a valve and the deviation signal between a detector and a setter. CONSTITUTION:When the set value of a temperature setter 31 is changed to a high temperature, the temperature deviation detected by a thermistor 30 is changed. A controller 32 which receives this deviation controls a valve part 33 through a driving part 34 at a uniform speed independently of the temperature deviation. When the temperature deviation is reduced to a prescribed value or smaller, the controller 32 controls the valve part 33 by a driving force proportional to the temperature deviation. When the set temperature approximates a target temperature, the controller 32 controls the valve part 33 at a low speed independently of the temperature deviation; and when it reaches the target temperature, the control of the valve part 33 is stopped. Since the characteristic is switched in accordance with the condition of the deviation signal in this manner, hunting is prevented and the responsiveness is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control valve device that controls fluid using a drive device.

2. Description of the Related Art Conventionally, there have been control valve devices of this type as shown in FIGS. 5 and 6.

FIG. 5 shows a hot water mixing device, in which a hot water side valve body 5 and a water side valve body 6 are provided inside a valve frame body 4 having a hot water inlet 1, a water inlet 2, and a mixing hot water outlet 3. The mixing ratio is adjusted by controlling the amounts of hot water and water in inverse proportion.

The hot water side valve body 5 and the water side valve body 6 are fixedly provided on a shaft 7, and this shaft 7 is connected to an external screw mechanism 8 and a gear 9.
It is driven by a DC type motor 1o via.

The temperature of the mixed hot water is detected by a temperature detector 11, and the temperature deviation from the temperature setting device 12 is determined by a control device 13.
control is performed so that the temperature of the mixed water set by the temperature setting device 12 is obtained by rotating forward or reverse depending on the temperature deviation.

FIG. 6 shows the concept of this conventional control method. Region where the temperature deviation is large on both the positive and negative sides (8)
In this case, the motor rotation speed is constant regardless of temperature deviation. In the region (B) where the temperature deviation is medium,
The drive is performed in proportion to the temperature deviation. In addition, in the region (C) where the temperature deviation is small, that is, close to the target temperature,
Rotation of motor 10 is stopped. The idea behind this control method is that the temperature detected by the temperature detector 11 is
By lowering the rotation speed of the motor 10 and slowly driving the motor 10 as it approaches the target temperature set in , so-called hunting, in which the temperature fluctuates around the target value, is prevented. Region (A) sets an upper limit on the rotation speed in order to obtain a predetermined driving force, and region (C) allows temperature fluctuations due to disturbances in a predetermined range near the target value, and controls the control operation. This is to prevent the motor 10 from continuously performing correction operations due to excessive sensitivity. The relationship between temperature deviation and motor rotation speed shown in Figure 6 shows an ideal state; in reality, the required driving force differs depending on the pressure difference between hot water pressure and water pressure and the valve position, so the difference will vary depending on the conditions. It gives rise to

Problems to be Solved by the Invention However, the conventional control valve device as described above has the following problems.

(1) Although the motor rotation speed was controlled in proportion to the temperature deviation, the flow of hot water and water also has inertia, and in the case of a mixing valve, the amounts of hot water and water change simultaneously, so the valve sensitivity is 2
If the temperature is doubled, it will be the same as when the temperature setting is changed significantly, and hunting may still occur because the change in flow rate will be large. It was necessary to reduce the proportionality constant.

(2) Therefore, by widening the area (C), the area that is not controlled will expand, and the discrepancy from the set target temperature will increase, and no correction will be made even if disturbances occur, resulting in large temperature fluctuations. became.

(3) Furthermore, if the proportionality constant is made small, the driving speed becomes slow, resulting in the disadvantage that it takes time to reach the target temperature, especially when the set temperature is changed.

As described above, conventional control valve devices do not satisfy the ideal control state of a control valve device, which is no hunting and good responsiveness.

The present invention provides a control valve device that solves these conventional problems, and an object of the present invention is to provide a control valve device that prevents hunting and has excellent responsiveness.

Means for Solving the Problems To achieve this object, the present invention provides a valve, a drive device,
A control valve device is composed of a control device that controls this, a detector that detects the state of the fluid, and a setter that sets the state of the fluid. It has a plurality of characteristics representing the relationship with the amount of operation of the valve. Furthermore, after the control is stabilized, a characteristic with a small gain is selected.

Operation The present invention satisfies the conflicting demands of switching the characteristics depending on the situation of the deviation signal, preventing hunting, and improving responsiveness by using the above-described configuration.

Embodiment Next, an embodiment of the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 shows an example in which a hot water mixing valve device according to an embodiment of the present invention is applied to a hot water supply system.

21 is a mixing valve that controls fluid, and distributes water introduced from the water supply 22 to a hot water side flow path 26 on the heat source device 25 side, which is composed of a burner 23 and a heat exchanger 24, and a water side flow path 27. ing. The hot water heated through the heat exchanger 24 is combined with water from the water side flow path 27 and mixed. The mixed hot water is sent to the terminal faucet 29 through the mixing vortex flow path 28, and hot water is supplied. The temperature of the mixed hot water is detected by a thermistor 30, which is a temperature detector provided in the mixing vortex flow path 28. The signal from the thermistor 30 is taken into the control device 32 together with a signal set by a temperature setting device 31, which is a setting device provided near the faucet 29 and setting the temperature of the mixed water. Control device 32 controls mixing valve 21 . Here, mixing valve 2
1 is constructed as shown in FIG. Mixing valve 21
is composed of a valve section 33 and a drive section 34. Inside the valve portion 33, a hot water side valve body 34 and a water side valve body 35 are provided that distribute water from the tap 22 into a hot water side flow path 26 and a water side flow path 27.

The hot water side valve body 34 and the water side valve body 35 are moved in parallel from side to side in the figure by a shaft 36, and change the ratio of flow rates to the hot water side and the water side in inverse proportion. The shaft 36 is driven by a step motor 39 via a screw mechanism 37 and a gear box 38, which are components of the external drive unit 34. A microswitch 40 detects the positions of the hot water side valve body 34 and the water side valve body 35.

This hot water mixing valve device is controlled as shown in the block diagram of FIG. The difference between the mixed water temperature detected by the thermistor 30 and the mixed water temperature set by the temperature setting device 31 is transmitted as a signal to the drive unit 34 calculated by the control device 32 as the number of drive pulses per hour.

In the drive section 34, a step motor 39 is driven, and as a result, the valve section 33 is driven and controlled, and continuously driven until the mixed water temperature reaches a set value.

The relationship between the temperature deviation and the number of driving pulses (resultingly, the number of motor rotations) is as shown in FIG.

Since the relationship between the temperature deviation and the number of driving pulses is point symmetrical with respect to the zero point, it will be explained in order from the range with the largest absolute value of the temperature deviation to the range with the smallest absolute value.

The control consists of a first region in which the number of driving pulses, which is the operating amount of the mixing valve 21, is constant regardless of the temperature deviation, a second region in which the temperature deviation and the number of driving pulses are proportional, and a temperature deviation and the number of driving pulses. The second region has a proportionality constant that is different from the second region in steps, and the second region has a drive pulse number of zero regardless of temperature deviation. Also, from the small range of temperature deviation to the large range,
As shown in the 2nd region where the temperature deviation is expanded, and the 2nd region where the temperature deviation is shifted from the Two characteristics are provided for the case where the signal changes from the state to the larger state, and the case where the signal moves toward a larger state. Hysteresis is provided.

The operation of the mixing valve 21 controlled in this manner will be explained. First, it is assumed that the range of each area is represented by the range of numerical values (unit: d e g) written in FIG. 4.

It is now assumed that a low temperature of 35° C. is set on the temperature setting device 31 and that mixed hot water at the specified temperature is being supplied from the faucet 29. In this state, if a high temperature is required and the setting value of the temperature setting device 31 is changed from 35°C to 60°C, the temperature deviation currently detected by the temperature setting device 31 and the thermistor 30 will be 60 - 35 = 25 degrees. , the temperature deviation falls within the positive region (■). For this reason, the step motor 3
9 rotates in the positive direction at a high speed constant pulse number determined in the first region. As a result, the hot water side valve body 34 opens the hot water side flow path 26, and the water side valve body 35 closes the water side flow path 27.

The reason for driving with a constant number of pulses in the first region is to ensure a predetermined driving force with a safety factor in mind, since if the number of pulses is increased too much, the driving torque will drop. Temperature deviation is l
When it falls below Qdeg, it enters the second region. Therefore, the number of drive pulses takes on a value proportional to the temperature deviation, and the speed is gradually reduced as the target temperature of 60° C. is approached. If the temperature deviation falls within 2688, the number of driving pulses will be 2 de.
The temperature deviation decreases rapidly from 2deg to lde
In the range of g, the step motor 39 is driven with a constant low number of pulses. In this region, the hot water side valve body 34 is rapidly opened and the water side valve body 35 is throttled, and the inertia of the flow of hot water and water, which has been changing, has an effect similar to that of temporarily applying a brake. This results in a reduction. Therefore, it is possible to take a large proportionality constant in the region (2). And the temperature deviation is lde
When reaching the second region below g, the number of drive pulses becomes zero and the drive of the step motor 39 is stopped. If you change the setting from this state back to the original 35°C using the temperature setting device 31,
Since the temperature deviation is 335-6O--25de, the motor rotates in the opposite direction to perform control to decrease the amount of hot water and increase the amount of water. The same control as above is performed depending on the following area.

Here, a description will be given of the provision of a plurality of characteristics for the same temperature deviation in the regions (1), (2), and (2), (2) and (2), and hysteresis. - It is assumed that the changed temperature reaches the target value and the mixed hot water temperature falls within the region (2) centered around the set value. Here, if hot water and water are not mixed sufficiently, the hot water temperature detected by the thermistor 30 may fluctuate even if the average mixed water temperature is as set. . In such a state, if a corrective action is applied just because a certain local temperature fluctuation of the thermistor 30 exceeds the region (2), the average temperature will fluctuate instead. Hysteresis is provided to prevent this, and once the target value is reached, the area is shifted to eliminate malfunctions.

In addition, if the mixed hot water temperature changes greatly from a stable state and exceeds ■゛ due to transient temperature fluctuations that occur when starting hot water supply or changing the flow rate, etc., the characteristics shift to quickly move the motor 39. . Then, as a result of operating the motor 39, when the temperature deviation decreases and reaches the state of region (①),
The characteristic returns to slowly moving the motor 39. Control words like this.

In position 32, the characteristic changes when a specific deviation is exceeded, and the characteristic shifts to a characteristic that quickly moves the motor 39, and when the deviation is heading toward a small state and falls below another specific deviation, the characteristic moves the motor 39 slowly. is switching to

In the above example, some of the characteristics have a plurality of characteristics and a hysteresis characteristic is provided, but in addition to this, all the regions other than the region [rvi] have a plurality of characteristics, but the region There are many other methods, including having multiple characteristics. The point is that there are parts that have multiple valve operation amounts for the same deviation signal, and a transition between characteristics is performed at a specific temperature deviation, especially when controlling fluids such as water. In the case of valves, depending on the inertia of the fluid, pressure, temperature, etc.
Although it is often difficult to perform good control with one characteristic, better characteristics can be obtained by setting certain switching conditions and using a plurality of characteristics.

Furthermore, since it has a plurality of characteristics, it is possible to deal with completely different control situations.

To give a practical example, in the case of an electric mixing valve combined with a gas instantaneous water heater, one characteristic could be used to control the mixing valve by adjusting the motor speed to adjust the temperature of the mixing valve in response to typical temperature deviations. , an example of using other characteristics for control to maintain the overall flow rate while maintaining the mixing ratio of the mixing valve and maintain the exit water temperature when the inlet water temperature of a gas instantaneous water heater falls and the exit water temperature falls below the mixing setting temperature in the winter. There is.

In the second region, the number of driving pulses of the step motor 39 is constant regardless of the temperature deviation in this embodiment, but it may be proportional to the temperature deviation. Further, although the second region has a first-order proportional relationship, it may have a second-order, third-order, or other proportional relationship, for example.

Furthermore, although the above embodiment uses an example in which the mixing valve is controlled according to the temperature deviation, the present invention can also be applied to a normal control valve, and the deviation can be controlled not only by the temperature deviation but also by the flow rate deviation and the pressure. Valve control using deviation can also improve controllability using a similar concept.

The main point of the above embodiment is that since the control device 32 switches the characteristics when a specific deviation is exceeded, the control device 32 quickly controls the motor only when a large transient temperature fluctuation exceeding the normal temperature control range occurs. 39, the normal slow characteristic is good and then shifts to the fast characteristic, and conversely, so-called stationary minute temperature fluctuations that cause hunting are not picked up and amplified.

Further, the value of the deviation to switch the characteristic to move the motor 39 quickly when going from a state with a small deviation to a state with a large deviation is as follows:
Since the value of the deviation is set larger than the value of the deviation which switches the motor 39 to a characteristic that moves slowly when the deviation goes from a large state to a small state, the result has hysteresis, and the average temperature changes due to local temperature fluctuations. This eliminates the occurrence of

Also, in the case of a mixing valve that changes the amount of hot water and water in inverse proportion,
With a normal valve, the result is similar to that of doubling the valve sensitivity, and the result is sensitive, but by controlling as in this embodiment, it is possible to obtain a stable mixed water temperature.

Effects of the Invention Since the control valve device of the present invention is configured as described above, it has the following effects.

(1) Since it has a plurality of characteristics representing the relationship between the deviation signal of the detector and setting device and the amount of operation of the valve by the drive device, a plurality of amounts of operation can be selected depending on the control conditions, and accurate control can be performed.

(2) After the temperature deviation between the detector and the setting device is large and falls within a predetermined deviation, select the characteristic with the smaller gain of multiple characteristics to temporarily stabilize the temperature and avoid small disturbances. control will not become unstable.

[Brief explanation of the drawing]

Fig. 1 is a diagram of a hot water supply system using an embodiment of the control valve device of the present invention, Fig. 2 is a sectional view of a mixing valve used in the system, and Fig. 3 is a control method used in the system. 4 is a control characteristic diagram of the system, FIG. 5 is a sectional view showing the configuration of a conventional valve device, and FIG. 6 is a control characteristic diagram of the conventional valve device. 21... Mixing valve, 30... Thermistor (detector), 31... Temperature setting device (setting device),
32... Control device, 33... Valve section (valve), 34... Drive section (drive device). Name of agent: Patent attorney Shigetaka Awano
To town) 恢Qco 恢Fig. 5 Fig. 6+

Claims (2)

[Claims] (1) A control valve that controls fluid, a drive device that drives the valve, a detector that detects the state of the fluid, a setting device that sets the state of the fluid, and a deviation signal between the detector and the setting device. A control valve device comprising: a control device that has a plurality of characteristics representing a relationship with the amount of operation of the valve by the drive device at the same deviation, and makes a transition between the characteristics. (2) After the temperature deviation between the detector and the setting device is large and falls within a predetermined deviation, the control according to claim 1 selects the characteristic with the smaller gain among the plurality of characteristics. Valve device.