JPS58224226A - Combustion control device - Google Patents

Abstract

PURPOSE:To get a control device having a high fuel adjusting ratio by a method wherein the upstream side pressure at the air throttle and the upstream side pressure of the gas throttle are alternatively sensed by the same pressure sensor through a pressure changing-over unit, and the gas proportional valve is controlled in such a way as the difference in output signals becomes zero. CONSTITUTION:In air fuel ratio control circuit 31, an output of amplifier 32 for amplifying an output signal of a pressure sensor is fed to an air pressure analogue meter 34 and a gas pressure analogue memory 35 through a change-over switch 4 which is changed over by a change-over signal generator 33 and then each of the values is stored and updated in synchronous with the changing-over signal. An electric current is fed from the changing-over signal generator to the solenoid coil 23. A difference between the output signals from each of the memories 34 and 35 is multiplied and amplified by a proportional valve driving circuit 36, and the electric current in the solenoid coil for the gas proportional valve 13 is adjusted in such a way as it becomes zero and then the volume of gas is controlled under a feed-back operation.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention automatically varies the combustion power (combustion power) according to the load, and the ratio of combustion air amount to gas (hereinafter referred to as air heat ratio) This invention relates to a high-load gas combustion control device used particularly in household appliances to maintain constant combustion stability and high efficiency.

The first conventional combustion control device for this type of high-load combustor.
The pressure equalization valve system (or zero governor system) shown in the figure is well known. That is, the combustion air sent by the blower 1 passes through the air-side throttle 2 to the mixing section 3, and the gas passes through the pressure equalizing valve 4.
The air passes through the gas-side throttle 5 and enters the mixing section 3, where the air and gas are mixed and combusted at a temperature 6.

In the back pressure chamber 7 of the pressure equalization valve, the pressure upstream of the air 1111 and the air 2 is at the center, and the pressure equalization valve 4 makes the pressure of the gas that does not come out equal to the pressure in the back pressure chamber. Here, the pressure upstream of the air side restriction 'fPAl (air), 1 is QA, the pressure of the '1st flow of the gas side restriction 'c pc, gas Fi
If i', 'jf Q' + the pressure of the mixing section is 4Pv, there is a constant relationship between the air-fuel ratio AQ=1: + and K2.

If the pressure equalizing valve can ideally be adjusted to Pc = Pm, the above equation will be obtained, and the air-fuel ratio will always remain constant even if the air-fuel ratio is changed.
Since the total differential pressure of is what moves the skeleton valve 9 mechanically,
A pressure setting error ΔPG always occurs due to the rigidity of the diaphragm, the change in the effective area of the diaphragm accompanying the displacement V, and the like.

That is, Pc=PA+ΔPc. That is, the error in the air-fuel ratio due to the error ΔPG becomes more serious as the absolute value of PA - PM becomes smaller.

Therefore, combustion h within a certain air-fuel ratio error range; in order to increase the adjustment ratio, PA-Pui must be increased or
The diaphragm of the pressure equalizing valve must be made thicker to reduce ΔPG.

For this reason, if you try to keep the fuel volume control ratio at ``Ao'', you will need an extremely large blower and pressure equalizing valve, which will result in large-sized equipment. When the generated differential pressure (PA-PM) is increased,
It was difficult to apply it to household combustion equipment (6), as it could not be used with household gas fuel such as city gas, which has a low gas supply pressure.

The present invention eliminates such conventional drawbacks, and provides a combustion control device with a large combustion h; control ratio and good air-fuel ratio stability without making the blower or valve device humanoid. purpose.

In order to achieve this object, the present invention provides a wind fan 1 which generates electricity according to the temperature of a heated body detected by a temperature detector.
The amount of combustion air is adjusted by controlling the variable mechanism, and the absolute pressure type or relative pressure type is controlled via the pressure switching device upstream of the air side restriction and gas side restriction respectively provided upstream of the mixing section. Measurements are taken alternately by the detector and switched in conjunction with the operation of the pressure switch of the pressure sensor. One word each is stored in the air pressure memory and gas pressure memory, and the difference between the respective signals read from each memory is determined. The gas proportional valve is controlled in accordance with the pressure difference signal generated by the pressure difference signal so that the pressure difference signal becomes zero.

Depending on its configuration, the combustion amount is automatically adjusted according to the load, and the air-fuel ratio is kept stable. Also, two pressure chips can be measured with the same pressure detector.1. By taking the difference between the stored pressure signals, errors such as temperature drift and variation of the temperature sensor itself are canceled out from the single pressure difference.

Embodiments of the present invention will be described in detail below with reference to the drawings. In the figure, parts that are the same as those in FIG. 1 are given the same numbers.

FIG. 2 is a block diagram showing one embodiment of the present invention, and only the main parts are shown in detail in cross section.

In the figure, 1 is a blower that supplies combustion air, and here, by controlling the rotation speed of the blower, a variable speed mechanism,
It consists of Reference numeral 2 denotes an air restrictor provided in the air passage, which generates a pressure difference at both ends according to the amount of air. Reference numeral 5 denotes a gas side throttle provided in the gas passage, and a pressure difference corresponding to the gas meter is generated at both ends of the throttle. Reference numeral 3 denotes a mixing section where air and gas meet, where the gas and air are mixed and the mixed gas is guided to the burner 6.

11 is a heat exchanger that heats the water passed through the vibrator.

12 is a thermistor that generates an electric signal according to the hot water temperature of the heat exchanger. 13 is a gas proportional valve and is a throttle on the gas side.
A movable iron core placed in the coil is placed in the first-flow gas passage and continuously adjusts the opening of the gas valve in accordance with the current flowing through the electromagnetic coil. 14(c) This is an eccentricity setting device, and the full width of tap water can be set by manually rotating the variable resistor. Reference numeral 16 denotes a hot water tapping control circuit, which amplifies the signal from the thermistor 12 and the temperature setting device 14 with a difference sound amplifier 41, and increases or decreases the rotation speed of the blower 1 with a rotation speed control circuit 42 to automatically adjust the necessary combustion air. .

It is a 16-piece semiconductor diffusion type pressure sensor, which introduces pressure.
21 is connected to the output hole 22 of the pressure switching device 17. The pressure switching device 17 is supported by the case 25 via the plate spring 24 by applying a current to the electromagnetic coil 23.
When the J' moving iron piece 26 is attracted to the fixed iron core 27, the gas pressure introduction hole 29 is opened by the elastic valve body 28 attached to the tip of the leaf spring.
is closed, and the air introduction hole 30 is opened.

When the electricity is not energized, the air pressure introduction hole 30 is closed by the restoring force of the plate screw 24, and the gas pressure introduction hole 29 is opened. However, the air-side throttle...upstream pressure is introduced into the air introduction hole, and the two pressures are alternately applied to the pressure sensor 16 in accordance with the timing of energizing the electromagnetic coil 23. Ru.

31 is an air-fuel ratio control circuit, and the output of an amplifier 32 that amplifies the output signal of the pressure sensor is sent to an air pressure analog memory 34 and a gas side pressure analog memory 35 via a reno switch isoner switched by a switching signal generator 33. The respective values are stored and updated in synchronization with the guided switching signal fL. The electromagnetic coil 23VC of the pressure switch 17 is also supplied with current from the switching generator 1d. Each memo 1734,
The difference between the output signals from the gas proportional valve 13 is integrally calculated and amplified by the proportional valve drive circuit 36, and the current of the electromagnetic coil of the gas proportional valve 13 is increased or decreased so that the difference between the output signals of the memo IJ34.35 becomes zero. is feedback controlled.

FIG. 3 is a graph showing an example of applied pressure versus output voltage of a semiconductor diffusion type pressure sensor.

Figure a shows the bH offset in the relationship between the output and the applied pressure in steady state, and is the output voltage when the applied pressure is zero. There are variations in pressure between these products. Figure c
This is an example of the characteristics of an H-pressure sensor when the ambient temperature changes, and the sensitivity to offset and pressure also changes. This
1- depends on the temperature characteristics of the semiconductor element, and generally varies much more greatly than the level of the pressure difference to be measured here. Although it can be corrected to some extent by trimming external circuits and internal elements, it cannot be completely corrected considering the increased cost.

In this embodiment, when detecting the difference in the royal forces between the applied pressures d and e, the same pressure sensor is used to alternately switch over a short period of time to detect the difference, so the difference between the outputs No. 13 of the memory circuit is
Therefore, both offset b) and its fluctuations are canceled out], ru. Furthermore, an air-fuel ratio control circuit with an integral element controls f and g.
Since the pressure is controlled to be as small as possible, it is almost unaffected by fluctuations in the pressure applied by the pressure sensor or fluctuations in linearity, etc. With a configuration of 0 or less, the accuracy of differential pressure detection can be increased. The air-fuel ratio can be kept stable even if the combustion amount adjustment ratio is increased without increasing the pressure difference between the air and gas side throttles.

As described below, according to the gas combustion control device of the present invention, an air-side throttle and a gas-side throttle are provided upstream of the air-gas mixing section, and a total pressure switch is installed upstream of each throttle. (1) By alternately detecting the pressure signals with the same pressure detector and storing the respective pressure signals in the memory, the gas proportional valve is set so that the difference between the output signals becomes zero (1) Since the error component of the pressure detector is canceled out, it is possible to control the air-fuel ratio as high as 4°/i degrees using an inexpensive pressure detector that does not require error correction, and the combustion i+f' and RM4 node ratios can be increased. . 1: The structure of the pressure sensor is simple because there is no skin necessary for a differential pressure type.

(b) Since the pressure generated by the restriction of the air and gas passages can be reduced as described above, the blower can be downsized and can also be applied to household gas fuels with low gas supply pressure.

(3) By adding an integral element, the effect of item 1 is further increased.

The above-mentioned process 11111 can be used with semiconductor pressure sensors with large characteristic fluctuations, so the dimensions of the pressure sensor can be found and the device can be downsized, and the 11111 of component arrangement can be made smaller.
Effects such as increased degree are dogs.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional gas combustion control device, FIG. 2 is a block diagram showing a gas combustion control device according to an embodiment of the present invention,
FIG. 3 is a graph showing applied pressure versus output voltage +1° of a semiconductor diffusion type pressure sensor used in an embodiment of the present invention. 1...Blower, 3...・Mixing section, 2...
... Air side throttle, 6... Gas side throttle, 6.
... Burner, 11 ... Heat exchanger, 13 ...
...Gas proportional valve, 12...Thermistor, 1
6...Pressure sensor, 17...Pressure switch, 34...Pneumatic pressure memory, 35...Gas pressure memory, 42...Rotation speed control circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure q) 2 Figures [53 Figures

Claims (1)

[Scope of Claims] (1) The mixing section includes a blower that supplies combustion well air, a mixing section that completely mixes gas and combustion air, a burner, and a heat exchanger that heats an object to be heated. An air-side throttle and a gas-side throttle are installed in the upstream air passage and gas passage, respectively, and a gas proportional valve in the gas passage that continuously varies the amount of gas supplied in response to an electrical signal, and a gas proportional valve that continuously varies the amount of air supplied in response to an electrical signal. an air star variable mechanism, an absolute pressure type or relative pressure type pressure detector,
A pressure switch which alternately switches between the pressure upstream of the air side throttle 9 and the gas side pressure and guides the pressure to the pressure detector; an air pressure memory and a gas pressure memory that electrically store pressure signals, respectively; a temperature detector that detects the temperature of the heated body at the outlet of the heat exchanger; and a temperature setting that sets the temperature of the heated body at the heat exchanger outlet. and controls the sound of the air volume variable mechanism according to the difference between the signal of the temperature detector and the temperature setting device No. 12, and according to the difference between the signal of the air pressure memory and the signal of the gas pressure memory. A combustion control device that controls the gas proportional valve so that the difference becomes zero. ? ) The combustion control device according to claim 1, wherein the pressure detector is a semiconductor diffusion type pressure sensor. (3) The combustion control device according to claim 1 or 2, wherein the gas proportional valve is controlled via an integral element.