JPS626152B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flow rate control device that automatically controls the flow rate of various fluids according to the amount of demand.

Taking a water heater as an example, the flow rate of fuel supplied to the burner needs to be controlled depending on the magnitude of the heat demand.

Generally, the flow rate is controlled by a proportional valve that compares the temperature of the water in the heat exchanger with a set value, and proportionally changes the valve opening depending on the size of the difference between the two. This is done by using .

However, simply using a proportional valve means,
When the valve opening is at a certain value, if the fuel source pressure changes, the fuel supply amount will also change automatically.

Therefore, conventionally, a regulator means having a function of keeping the pressure in the outlet passage constant even if the source pressure fluctuates is disposed in front of the proportional valve means. However, this configuration requires the above-mentioned two means, resulting in a problem that the device becomes complicated and expensive.

This invention was made to solve the above problems, and when the pressure in the output passage fluctuates, the opening of the valve is automatically adjusted to compensate for this fluctuation and maintain the pressure constant. The object of the present invention is to obtain a flow rate control device having a function of adjusting the flow rate.

In order to achieve the above object, the present invention provides an actuator including an electromagnetic pressure feeding device for force-feeding fluid to a pressure chamber, a responsive body that senses the pressure within the pressure chamber and displaces the fluid, and a responsive body that responds to the displacement of the responsive body. A valve body that changes the size of the opening of a port formed between the inlet passage and the outlet passage, a pressure sensor that generates an output signal corresponding to the pressure in the outlet passage, and a detection of the pressure sensor. and an actuator drive circuit that controls the actuator so that the pressure in the outlet passage always remains at a constant value based on a comparison signal between the value and the set value.

The actuator drive circuit according to the present invention controls the actuator based on a comparison signal between the detection value of the pressure sensor that detects the pressure in the outlet passage and a set value, and changes the pressure in the pressure chamber of the actuator to maintain the pressure. By adjusting the opening degree of the valve body using the responding body and keeping the pressure in the outlet passage constant, the fuel can flow out from the outlet passage even if the source pressure fluctuates without using a regulator means. can be kept constant at all times.

Next, an embodiment of the present invention will be described with reference to the drawings. The valve body designated by reference numeral 1 in FIG. ,
The pressure of the fuel gas in the outlet passage 4 is controlled. In order to detect this pressure, a pressure sensor 6 is provided which generates an output signal corresponding to the pressure within the outlet passage 4.

The actuator 2 is an electromagnetic pump 2 housed in a casing 21, as shown in detail in FIG.
It has 2. This electromagnetic pump 22 receives a drive signal supplied to a coil 23 from a drive circuit 14 to be described later, and transfers a liquid (for example, oil) contained in a first chamber 24 formed in the casing 21 to a second chamber. This second chamber 25
The pressure inside displaces a responsive body 27 connected to the valve body 1 via a rod 26. Further, a communication passage 28 for returning the fluid in the second chamber 25 to the first chamber 24 is provided, and this communication passage 28
The orifice 29 provides a predetermined resistance to the fluid flowing therein.

Therefore, when a drive signal is supplied from the drive circuit 14, the electromagnetic pump 22 pumps the liquid in the first chamber 24 to the second chamber 25 to increase the internal pressure, and senses this increase in pressure. The response body 27 moves downward in the figure. Due to this movement of the response body 27,
The valve body 1 descends against the spring 7 and opens the port 5.
Increase the opening area. Further, when the pressure in the second chamber 25 decreases, the valve body 1 rises together with the responsive body 27 due to the action of the spring 7, thereby reducing the opening area of the port 5. This movement of the valve body 1 controls the gas pressure within the outlet passage 4, and this gas pressure is detected by the pressure sensor 6. Under normal conditions,
Gas pressure is proportional to the amount of gas supplied.

FIG. 3 shows another form of actuator 2 applicable to the present invention. In this example, an electromagnetic compressor 32 for pumping air into a pressure chamber 31 corresponding to the second chamber 25 is used instead of the electromagnetic pump 22 shown in FIG. This electromagnetic compressor 32 has a coil 33 to which a drive signal is supplied, and a cylindrical body 35 that supports a plunger 34 that reciprocates at the center of the coil 33. A piston 36 movable within a cylinder 35 is connected to the plunger 34.
By the reciprocating motion of 6, the inside of the cylinder chamber 37 formed in the cylinder 35 is alternately pressurized and depressurized. This cylinder chamber 37 has a check valve 38 and a check valve 38, respectively.
The suction chamber 40 communicates with a suction chamber 40 and a discharge chamber 41 containing a
Further, the discharge chamber 41 is connected to the pressure chamber 31 through the communication hole 43.
are connected to each other. The discharge chamber 41 also includes a passage 44 having a flow rate restricting means such as an orifice.
It also communicates with the outside via. Further, the check valve 38 is pressed by a spring 45 in the direction of closing the suction hole 42, and the check valve 39 is pressed by the spring 46 in the direction of closing the passage between the cylinder chamber 37 and the discharge chamber 41. There is.

A plunger 34 and a piston 36 connected thereto are driven by a drive signal supplied to the coil 33.
When the pressure chamber 31 reciprocates, air sucked through the suction hole 42 is forced into the pressure chamber 31, and the pressure inside the chamber 31 increases. That is, when the piston 36 moves upward in FIG. Air is inhaled. Also piston 36
In the process of descending, the air in the cylinder chamber 37 and the suction chamber 40 is compressed, so the check valve 38 is held in the position where the suction hole 42 is closed.
The check valve 39 moves against the spring 46 and opens a passage between the cylinder chamber 37 and the discharge chamber 41. As a result, the air in the cylinder chamber 37 is
Pressure chamber 31 through discharge chamber 41 and communication hole 46
A portion of the fluid flows into the interior and a portion is discharged to the exterior through the passage 44. When the pressure inside the pressure chamber 31 increases due to this operation, the responsive body 27 is pushed down, and the valve body 1 connected to the responsive body 27 via the rod 26 moves in the opening direction, as in the case of FIG. .

The gas flowing into the outlet passage 4 from the inlet passage 3 through the port 5 is supplied to the burner 8 through normal piping and is used as fuel for heating the heat exchanger 9. Further, a temperature sensor 10 is provided to detect the temperature of water in the heat exchanger 9.

The comparator 11 sets a set value SP indicating the desired water temperature.
and the actual temperature of the water in the heat exchanger 9 detected by the temperature sensor 10, that is, generates an output signal corresponding to the magnitude of the heat demand, and this heat demand signal is sent to the signal conversion circuit. After being subjected to predetermined signal processing at step 12, the signal is sent to a second comparator 13. This comparator 13 has a function of comparing the output of the signal conversion circuit 12 and the output signal of the pressure sensor 6, and sending an output corresponding to the difference to the drive circuit 14. The output of the second comparison circuit 13 therefore corresponds to the difference between the magnitude of the heat demand and the gas pressure in the outlet passage 4, ie the flow rate of the fuel gas supplied to the burner 8. The drive circuit 14 supplies a drive signal according to the output of the comparator 13 to the actuator 2, and controls the position of the valve body 1 so that the output of the pressure sensor 6 becomes a value commensurate with the magnitude of the heat request. Such control is achieved by changing the frequency, voltage level, or duty ratio of the drive signal supplied to the actuator 2, thereby changing the flow rate of the fluid pumped by the electromagnetic pump 22 or the electromagnetic compressor 32. It's easy to do.

An example of a specific circuit configuration of the drive circuit 14 is shown in the fourth example.
As shown in the figure. This drive circuit 14 includes a multivibrator 51 that generates a sawtooth wave of a constant frequency;
Based on this sawtooth wave, a variable pulse width one-shot multivibrator 52 generates a pulse output whose frequency is constant but whose pulse width changes.
and a transistor Q1 which is repeatedly turned on and off in response to this pulse output, and an actuator 2 is connected as a load of this transistor Q1.

The multivibrator 51 has a PUT element Q2, and a constant voltage determined by a resistor R1, a Zener diode D1, and resistors R2 and R3 is applied to its gate. Also, PUT element Q2
A terminal voltage of a capacitor C1, which receives charging current through a resistor R4, is applied to the anode of the capacitor C1. Immediately after power is turned on, capacitor C1 is not charged, so the anode potential of PUT element Q2 is lower than the gate potential, and PUT element Q2 is non-conductive. Then, as charging of the capacitor C1 progresses and the anode potential rises to the gate potential,
PUT element Q2 suddenly conducts and capacitor C1
The charge is instantly discharged through PUT element Q2 and resistor R5. This operation is continuously repeated at a constant period, and as a result, a sawtooth wave with a constant frequency appears on the anode side of the PUT element Q2.

On the other hand, the variable pulse width one-shot multivibrator 52 has an inverting amplifier 53 which receives at its inverting input the sawtooth wave output appearing on the anode side of the PUT element Q2, and its non-inverting inputs include a resistor R6 and a variable resistor VR. A set voltage determined by is applied. Therefore, at the output terminal of the inverting amplifier 53,
A pulse output whose level changes every time the potential of the inverting input crosses the potential of the non-inverting input is obtained, and this output is applied to the base of the transistor Q1 via the resistor R7. This results in transistor Q1
A pulse current flows through the actuator 2, which is the load. The set voltage applied to the non-inverting input of the inverting amplifier 53 is variable by a variable resistor VR, and by changing this voltage,
The slice level for the sawtooth signal changes,
The pulse width of the output signal changes. The resistance value of the variable resistor VR is configured to be adjusted by the output of the comparator 13 in FIG. changes depending on the output of the comparator 13.

As described above, according to the flow rate control device of the present invention, the position of the valve body 1 is automatically controlled so that the pressure in the outlet passage 4 is always at a desired constant value, and this value is equal to the set value. It is determined by the heat demand signal, which is the difference between the temperature of the load and the temperature of the load. Therefore, gas is stably supplied to the burner 8 at a flow rate that meets the actual heat requirement, and control accuracy is greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a flow rate control device according to an embodiment of the present invention, FIG. 2 is a vertical sectional view of an actuator used in the flow rate control device, and FIG. 3 is a vertical sectional view of another actuator. , FIG. 4 is a circuit diagram of the drive circuit. 1... Valve body, 2... Actuator, 3... Inlet passage,
4... Outlet passage, 6... Pressure sensor, 8... Burner, 9
...Heat exchanger, 10...Temperature sensor, 11...Comparator,
12... Signal conversion circuit, 13... Comparator, 14... Drive circuit, 22... Electromagnetic pump, 23... Coil, 24...
1st chamber, 25...2nd chamber, 26...rod, 27...response body, 31...pressure chamber, 32...electromagnetic compressor,
33... Coil, 36... Piston, 51... Multivibrator, 52... Pulse width variable one shot multivibrator, 53... Inverting amplifier.

Claims (1)

[Claims] 1. An actuator equipped with an electromagnetic force-feeding device for force-feeding fluid to a pressure chamber and a responsive body that senses the pressure in the pressure chamber and displaces, and an inlet passage and an outlet passage according to the displacement of the responsive body. a valve body that changes the size of an opening of a port formed in the outlet passage, a pressure sensor that generates an output signal corresponding to the pressure in the outlet passage, and a signal that compares a detected value of the pressure sensor with a set value. and an actuator drive circuit that controls the actuator so that the pressure in the outlet passage is always at a constant value.