JPH11338548A - Gas flow rate controller and combustion controller equipped with the controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a gas flow rate controller which is suitable for gas flow rate control of a large flow rate and to carry out precise air-fuel ratio control by using the gas flow rate controller. SOLUTION: The opening extent of a hydraulic control valve 25 is adjusted by driving a piston 20a where a valve 18 is coupled by generating the oil pressure of a hydraulic actuator 20 by a hydraulic pump 23 according to a detection signal generated by a mass-flow sensor 15 to control the flow rate of gas 14. Gaseous fuel and an air amount are controlled by using this gas flow rate controller to perform accurate air-fuel ratio control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas flow control device and a combustion control device provided with the gas flow control device.

[0002]

2. Description of the Related Art Conventionally, a gas flow control device driven by a solenoid coil has been known (Japanese Unexamined Patent Publication No.
-219616, etc.). FIG. 6 is a diagram showing the configuration of such a conventional gas flow control device driven by a solenoid coil. In FIG. 6, reference numeral 1 denotes a gas flow control valve for controlling the flow of gas 2; , 3
a is an upstream passage, 3b is a downstream passage, 3c is a partition wall,
3d is an opening, 4 is a drive solenoid, 4a is a valve plug,
4b is a guide ring, 5 is a flow rate sensor, 5a is a suction pipe,
5b is an exhaust pipe, 5c is a thermal IC sensor, 5d is a filter, and 6 is a controller.

Next, the operation of the conventional gas flow control device will be described. The flow rate of the gas 2 is determined by the thermal IC sensor 5
c, and a detection signal is input to the controller 6. A drive signal is output to the drive solenoid 4 based on this detection signal, the valve plug 4a moves up and down, and the opening degree of the opening 3d is changed. Then, the flow rate of the gas 2 flowing from the upstream passage 3a to the downstream passage 3b is controlled. Such a gas flow control device is also used in a combustion control device to accurately control the air-fuel ratio.

[0004]

The conventional gas flow control device is configured as described above, and there is a limit to the driving force of the valve in driving a solenoid coil. On the other hand, a large gas flow control device used in the combustion control device is required, and a conventional solenoid-driven device is not suitable for adjusting a large flow gas flow. The conventional one has a problem that it is desired to eliminate such inconvenience. Furthermore,
There is also a demand for a gas flow control device having a function as a safety shut-off valve for instantaneously shutting off fuel in an emergency.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a gas flow control device suitable for controlling a large flow of gas.

Another object of the present invention is to provide a combustion control device having such a gas flow control device and capable of performing precise air-fuel ratio control.

[0007]

A gas flow control device according to the present invention comprises a hydraulic actuator having a cylinder filled with oil and a piston driven by hydraulic pressure in the cylinder; Hydraulic control means for controlling the hydraulic pressure, a flow path through which the gas flows, a gas control valve connected to a piston of a hydraulic actuator for controlling the flow rate of the gas flowing through the flow path, and a flow rate of the gas flowing through the flow path And a gas flow control means for controlling the opening of the gas control valve by giving a command to the hydraulic control means so that the flow rate of the gas becomes a predetermined value based on the detection signal from the gas flow meter It is provided with.

In the gas flow control device according to the present invention, a relief valve for lowering the oil pressure in the cylinder and a gas control valve are connected so as to cut off the gas flow as the oil pressure in the cylinder decreases. And a spring for biasing the piston.

A gas flow control device according to the present invention includes a diagnosis means for diagnosing a hydraulic system based on a relationship between a control signal for controlling a hydraulic control means and a detection signal from a gas flow meter. is there.

[0010] A combustion control device according to the present invention includes the gas flow control device, controls the flow rate of gaseous fuel supplied to the burner to a predetermined value, and detects the amount of air in a ventilation passage for feeding air. A mass flow meter, and an air amount control means for controlling an amount of air supplied to the burner so as to have a predetermined air-fuel ratio in the burner based on an air amount detected by the mass flow meter. is there.

The combustion control device according to the present invention comprises a storage means for storing an air-fuel ratio in accordance with a degree of heat demand, and a temperature adjusting means for inputting a heat demand value. The means reads out the air-fuel ratio stored in the storage means and controls the flow rates of gaseous fuel and air in accordance with the heat demand value input from the temperature control means.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 In FIG. 1, 11 is a gas flow control valve,
Reference numeral 12 denotes an upstream passage (flow passage) of the gas flow control valve 11 into which the gas 14 flows, reference numeral 13 denotes a downstream passage (flow passage) from which the gas 14 flows, and reference numeral 15 denotes a mass flow sensor for detecting the flow amount of the gas 14 ( Gas flow meter), 16 is a partition wall, 17 is an opening of the partition wall 16, 18 is a valve body (gas control valve) that closes or opens the opening 17, 19 is a valve body 18, and the opening 17 is closed. 20 is a hydraulic actuator, 20a is a piston of the hydraulic actuator 20 connected to the valve body 18, 20b is a cylinder filled with oil to guide the piston 20a up and down,
In order to prevent oil from flowing through a gap between the piston 20a and the cylinder 20b, the outer circumference of the piston 20a is
The hydraulic actuator 20 is configured so that the inner periphery of the hydraulic actuator 0b closely slides smoothly. The cylinders 20 and 22 both extend from a position above the top dead center of the piston 20a to a position below the bottom dead center of the piston 20a.
b, a hydraulic pump (hydraulic control means) interposed in the communication pipe 21 to generate hydraulic pressure in the cylinder 20b; 24, a relief valve connected to the communication pipe 21 in parallel with the pump 23; Reference numeral 25 denotes a hydraulic control valve (hydraulic control means) interposed in the communication pipe 22. In the first embodiment, an on-off valve is used as the relief valve 24 and a proportional valve is used as the hydraulic control valve 25. However, other types of valves are selected so as to obtain optimal characteristics in design. It does not matter.

Reference numeral 31 denotes a controller including a CPU (gas flow control means, diagnostic means, air flow control means) 32, a memory (storage means) 33, and an I / O interface 34.

As the mass flow sensor 15, for example, the one shown in FIG. 6 disclosed in the specification of Japanese Patent Application No. 9-287180 is used. Most (mainstream) of the combustion gas flowing from the inlet side of the mass flow meter passes through a plurality of holes provided in the orifice plate 5 (in this case, the reference numerals in this publication are used, the same applies hereinafter). However, only a small part of the combustion gas is split and flows to the branch pipe 11, and after passing through the detector 14, merges with the main stream and flows out of the outlet side. Since the main stream and the branch stream are provided so as to have a predetermined relationship in advance, the flow rate of the main stream can be known by measuring the flow rate of the branch stream. In applications where the flow rate of the gas to be measured is large, such a split flow type mass flow meter is used. As the detector 14, for example, a diaphragm type thermal flow sensor disclosed in Japanese Patent Application Laid-Open No. Hei 4-23808 (Japanese Patent Application No. Hei 3-106528) is used. It is known that a thermal flow sensor can obtain a detection signal corresponding to a mass flow rate in principle.

The detector for detecting the mass flow rate is as follows.
In addition to the above-mentioned diaphragm type, a type in which a heat-sensitive coil is wound around a thin tube and a type called a hot-wire type are known, and these can also be adopted.

Next, the operation will be described. Relief valve 2
When the valve 4 is open, the oil can freely flow through the relief valve 24, so that the oil pressure in the cylinder 20b does not increase regardless of the driving state of the pump 23. Therefore, the valve element 18 is urged by the spring 19 to open the opening 17.
Is closed. When the hydraulic pump 23 is driven by closing the relief valve 24 and the hydraulic control valve 25, the hydraulic pressure below the piston 20a in the cylinder 20b increases, and the piston 20a
Lifts the valve element 18 upward against the urging force of the spring 19. As a result, the opening 17 is opened, and the gas 14 flows from the upstream passage 12 to the downstream passage 13.

The flow rate of the gas 14 is determined by the mass flow sensor 1
5 and the detection signal is
It is input to PU32. The CPU 32 calculates the flow rate of the gas 14 based on the detection signal.

When the flow rate of the gas 14 exceeds the upper limit of the range to be controlled, the controller 31 opens the hydraulic control valve 25 by an amount corresponding to the difference between the detected value of the gas flow rate and the set value. By opening the hydraulic control valve 25, the oil below the piston 20a flows through the hydraulic control valve 25 to the upper side of the piston 20a, and the hydraulic pressure below the piston 20a decreases. The piston 20a is pushed down by the urging force of the spring 19 by the decrease in the oil pressure, the opening 17 is narrowed, and the gas flow rate is reduced. As described above, when the detected gas flow rate value matches the set value, control is performed so that the force between the hydraulic pressure and the urging force of the spring 19 is balanced.

Next, when the flow rate of the gas 14 becomes less than the lower limit of the range to be controlled, the operation in the opposite direction is performed, the opening 17 widens, and the gas flow rate increases. In this way, the gas flow rate is controlled to be within the predetermined range.

Here, an example in which the hydraulic pressure is controlled by changing the opening of the hydraulic control valve 25 has been described. However, the opening and closing of the hydraulic control valve 25 can be controlled in a time-division manner.
That is, the hydraulic pressure can be controlled by opening and closing the hydraulic control valve 25 at a certain cycle and changing the ratio between the open time and the close time.

Although an example using the hydraulic control valve 25 as the hydraulic control means has been described here, other means may be used. For example, if the drive motor for the hydraulic pump 23 is controlled by inverter speed control without providing the hydraulic control valve 25, and the motor speed is controlled by the controller 31, the discharge of the hydraulic pump 23 according to this speed is controlled. Pressure can be obtained. Further, in an emergency, if the oil pressure applied to the piston 20a is released by opening the relief valve 24, the opening 17 can be shut off, for example, within one second.

As described above, according to the first embodiment, since a large driving force can be obtained by the hydraulic actuator 20, an effect that a large gas flow rate can be accurately controlled can be obtained.

Second Embodiment In a second embodiment, a diagnosis of a hydraulic system is performed in the gas flow control device in the first embodiment. The configuration of the second embodiment is different from that of the first embodiment. Is the same. Incidentally, the memory 33, the threshold L ₂ for determining the fault to a threshold L1 for determining the deterioration of the hydraulic system in the signal level X of the control signal output to the hydraulic control valve 25 (L _1> L ₂₎ Are stored.

Next, the operation will be described with reference to the flowchart of FIG. In step ST1, the hydraulic control valve 2
The signal level of the control signal output to 5 is fixed at X.

In step ST2, the mass flow sensor 1
5, a detection signal corresponding to the flow rate detection value is input, and the signal level L of the detection signal is compared with a threshold L ₁ at the signal level X of the control signal output to the hydraulic control valve 25.
As shown in FIG. 3, in the initial state, the signal level L of the detection signal of the mass flow sensor 15 when the signal level of the control signal is X is L _0, and the hydraulic system is normal. However, the hydraulic system is subject to oil leakage and hydraulic pump 2
3 may occur.

[0026] be lower than the signal level L is a threshold L ₀ of the detection signal, when the threshold L ₁ greater than the step ST
Proceeding to 3, it is determined that the hydraulic system is normal. Further, when the signal level L of the detection signal becomes the threshold value L ₁ or less, the process proceeds to step ST4, comparing the signal level L of the detection signal with the threshold value L _2.

[0027] When the signal level L of the detection signal exceeds the threshold value L _2, the process proceeds to step ST5, for example, hydraulic system degradation occurring oil leakage and the hydraulic pump 23 is determined to be deteriorated. Also when the signal level L of the detection signal is threshold L ₂ following the process proceeds to step ST6, determines a failure.

As described above, according to the second embodiment, the signal level L of the detection signal is changed to the signal level X of the control signal.
Since the diagnosis of the hydraulic system is performed in comparison with the threshold values L ₁ and L _{2 at} the time of ( ₁₎ , an effect that oil leakage, deterioration of the hydraulic pump 23, and the like can be diagnosed is obtained.

Embodiment 3 Embodiment 3 is an embodiment in which the gas flow control device according to Embodiment 1 is applied to a combustion control device.

Conventionally, there has been known a combustion control apparatus for accurately controlling the air-fuel ratio by controlling the flow rates of gaseous fuel and air. However, in the conventional combustion control apparatus, a damper motor for air is used in accordance with a heat demand. , The air pressure is once received by the diaphragm, the ball valve is opened and closed, and the position of the hydraulic cylinder is controlled to control the pressure of the gaseous fuel.

However, in such a combustion control device, since the flow rate of the gaseous fuel is controlled alternately by the pressure, the air-fuel ratio cannot be controlled accurately, and it is possible to completely prevent misfire, incomplete combustion, and the like. Can not. In addition, since the air-fuel ratio cannot be accurately controlled, an excessive amount of air has to be set, and the turndown ratio, which is the Hi / Lo combustion ratio, is at most 2 or 3.

In general, a burner is designed to improve the combustion efficiency at the time of high combustion, and at the time of low combustion, incomplete combustion tends to occur unless the air amount is large.
It is desirable to change the air-fuel ratio according to the amount of combustion. Therefore, in the third embodiment, the gas flow rate control device of the first embodiment is used, the flow rate is adjusted without passing through the diaphragm, and accurate air-fuel ratio control according to the combustion amount is performed.

In FIG. 4, 41 is a burner, 42 is a gas fuel supply path for guiding gaseous fuel to the burner 41, 43 is an air supply path for guiding air to the burner 41, and 44 is a fan motor for feeding air (air flow control). Means, 45 a damper (air amount control means) for adjusting the amount of air, 46 a mass flow meter for detecting the amount of air, 47 a temperature controller (temperature adjusting means) for inputting a heat demand value. is there. The same elements as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

Next, the operation will be described. Gaseous fuel is
The gas fuel is supplied to the burner 41 through the gas fuel supply path 42, the flow rate of the gas fuel is detected by the mass flow sensor 15, and the detection signal is input to the controller 31.
The air is supplied to the air supply passage 43 by a fan motor 44.
The air amount is sent to the burner 41 via the mass flow meter 46, and the detection signal is input to the controller 31.

The required heat value is inputted from the temperature controller 47 and inputted to the controller 31. Controller 3
The air-fuel ratio (how many times the stoichiometric air amount) corresponds to the degree of heat demand as shown in FIG.
Is stored. For example, in FIG. 5, when the degree of the heat demand is Y, the optimum air-fuel ratio is 1.2%
Is selected.

The controller 31 reads the air-fuel ratio, controls the valve element 18 based on the detection signal from the mass flow sensor 15 so that the flow rate of the gaseous fuel becomes a predetermined value based on the air-fuel ratio, and controls the air-fuel ratio. The damper 45 is controlled based on the detection signal from the mass flow meter 46 so that the amount becomes a predetermined amount.
Control the opening degree. In this way, the air-fuel ratio is accurately controlled to a predetermined value, and the gas fuel burns in the burner 41 at this air-fuel ratio. Here, although the air amount is controlled by the opening degree of the damper 45, the air amount may be controlled by changing the rotation speed of the fan motor 44 without using the damper 45.

As described above, according to the third embodiment, the hydraulic actuator 2 is provided in the gas flow control valve 11.
Since a driving force greater than 0 is obtained, it can be sufficiently used for flow control of a large flow rate such as gaseous fuel, and the air-fuel ratio is controlled according to the combustion amount based on the actual flow rate. It can accurately control the air-fuel ratio, prevent the excessive flow of cold air and prevent heat loss, suppress the generation of carbon monoxide and nitrided oxide, and improve the combustion efficiency. Can be improved.

Further, the response speed is faster than that of the conventional diaphragm type combustion control device, and it can cope with furnace pressure fluctuations due to wind pressure, temperature changes of air and gaseous fuel, and easy zero adjustment and span adjustment. Then, the turndown ratio (Hi
/ Lo combustion ratio) is also increased, and the fuel / air ratio at each point in the proportional band can be programmed.

Further, the air-fuel ratio according to the degree of the heat demand is temporarily stored in the memory 33, and the air-fuel ratio is read out according to the heat demand from the temperature controller 47 to control the flow rates of the gaseous fuel and the air. Therefore, the effect that more precise combustion control can be performed can be obtained.

[0040]

As described above, according to the present invention, a large driving force can be obtained by the hydraulic actuator,
There is an effect that a large gas flow rate can be accurately controlled.

According to the present invention, the flow of a large amount of gas can be instantaneously interrupted in an emergency.

According to the present invention, there is an effect that it is possible to diagnose oil leakage, deterioration of the hydraulic pump, and the like.

According to the present invention, it is possible to adapt to a flow rate control of a large flow rate, and it is possible to accurately control the air-fuel ratio based on the actual flow rate. Accordingly, it is possible to suppress the generation of carbon monoxide and nitride oxide, and to prevent the flow of excessive air (cool air), thereby preventing a decrease in the amount of heat in the combustion chamber and improving the combustion efficiency.

According to the present invention, combustion can be performed at an optimum air-fuel ratio according to the amount of combustion, and in particular, incomplete combustion during low combustion can be prevented.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of a first embodiment according to a gas flow control device of the present invention.

FIG. 2 is a flowchart showing a diagnostic operation according to a second embodiment of the gas flow control device of the present invention.

FIG. 3 is an explanatory diagram of the diagnostic operation of FIG. 2;

FIG. 4 is a configuration diagram showing a configuration of a third embodiment according to the combustion control device of the present invention.

FIG. 5 is an explanatory diagram showing the operation of FIG. 4;

FIG. 6 is a configuration diagram showing a configuration of a conventional gas flow control device.

[Explanation of symbols]

Reference Signs List 12 upstream passage (flow passage) 13 downstream passage (flow passage) 15 mass flow sensor (gas flow meter) 18 valve body (gas control valve) 19 spring 20 hydraulic actuator 20a piston 20b cylinder 23 hydraulic pump (hydraulic control means) 24 Relief valve 25 Hydraulic control valve (hydraulic control means) 32 CPU (gas flow control means, diagnostic means, air flow control means) 33 Memory (storage means) 41 Burner 44 Fan motor (air flow control means) 45 Damper (air flow control) Means) 46 Mass flow meter 47 Temperature controller (Temperature control means)

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Koichi Iwase 2-12-19 Shibuya, Shibuya-ku, Tokyo Inside Yamatake Ha Newel Co., Ltd.

Claims (5)

[Claims] A hydraulic actuator having a cylinder filled with oil and a piston driven by hydraulic pressure in the cylinder; hydraulic control means for controlling the hydraulic pressure in the cylinder of the hydraulic actuator; A gas control valve connected to a piston of a hydraulic actuator to control a flow rate of gas flowing through the flow path; a gas flow meter that detects a flow rate of gas flowing through the flow path; A gas flow control device, comprising: gas flow control means for controlling a degree of opening of a gas control valve by giving a command to a hydraulic control means so that a gas flow rate becomes a predetermined value based on a detection signal. 2. A relief valve for lowering the oil pressure in the cylinder, and a spring for urging a piston to which a gas control valve is connected so as to cut off the flow of gas as the oil pressure in the cylinder decreases. The gas flow control device according to claim 1, further comprising: 3. A diagnostic device for diagnosing a hydraulic system based on a relationship between a control signal for controlling the hydraulic control device and a detection signal from a gas flow meter. Item 3. The gas flow control device according to Item 2. 4. An air flow control device comprising the gas flow control device according to claim 1, wherein the air flow is controlled by controlling the flow rate of gaseous fuel supplied to the burner to a predetermined value and sending air. A mass flow meter for detecting the amount of air in the road; and an air amount for controlling the amount of air supplied to the burner so as to have a predetermined air-fuel ratio in the burner based on the air amount detected by the mass flow meter. A combustion control device, comprising: a control unit. 5. A storage device for storing an air-fuel ratio in accordance with a degree of heat demand, and a temperature adjustment means for inputting a heat demand value, wherein the gas flow rate control means and the air flow rate control means comprise a temperature adjustment means. 5. The combustion control device according to claim 4, wherein the air-fuel ratio stored in the storage unit is read out to control the flow rates of the gaseous fuel and the air in accordance with the heat demand value input from the control unit.