JPH03175208A - Automatic air/fuel ratio correction device - Google Patents

Abstract

PURPOSE:To provide an ideal air/fuel ratio by detecting the pressure and temperature of supplied preheated air and by installing a pressure sensor and temperature sensor to an air duct and regulating fuel pressure by the calculation in a calculation circuit based on the detected values. CONSTITUTION:A pressure sensor 5 and temperature sensor 6 that are installed to an air duct 2 convert detected values to electric signals, and those converted electric signals are sent from amplifiers 16 and 17 to converters 18 and 19, and there they are converted from analog signals to digital signals. Then they are inputted to a calculation circuit 9 via an input port 20. In the calculation circuit 9 they are compared with constant and coefficient terms according to a program, and ideal fuel supply pressure for the temperature and pressure are calculated at once, and the calculated ideal fuel supply pressure is outputted as an output via an output port 21 to select a line for an actuator with an air regulating valve 22 that is installed to a pressure equalizing valve actuating pressure pipe 13, and the output signal is converted from digital to analog by a converter 23, amplified by an amplifier 24, and a signal of a level capable of operating an actuator 25. And here for the first time the signal drives the actuator as a control signal to regulate the fuel gas pressure.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an automatic air-fuel ratio correction system used in a combustion device that uses exhaust heat to preheat combustion air to improve efficiency. (m adjustment) device.

[Prior art] In combustion equipment that uses preheated air for combustion, fluctuations in the temperature of the preheated air cause fluctuations in the air-fuel ratio, making it impossible to achieve ideal combustion and causing problems such as reduced efficiency and exhaust gas pollution. It is known to do.

Therefore, in the past, in order to maintain a constant air-fuel ratio when a fluctuation occurred in the preheated air temperature, the air flow rate was measured and the air flow rate or the fuel flow rate, or both were corrected and controlled based on this measured value. is being carried out.

However, it has been pointed out that in the above adjustment means, temperature fluctuations cause fluctuations in combustion air pressure, and this pressure fluctuation causes fluctuations in the air-fuel ratio, but this point is not taken into account.

Therefore, as a means to solve this problem, a proposal has been made to grasp the expansion or contraction effect of the thermal expansion fluid due to the temperature change of the combustion air, and control the fuel control means based on the degree of expansion or contraction to maintain the air-fuel ratio constant. be.

[Problems with the Prior Art] However, in the air-fuel ratio adjusting means using the expansion fluid, the device becomes complicated, and there are problems with the heat resistance of the expansion fluid, management, and ability to follow air temperature fluctuations.

It is an object of the present invention to propose an automatic air-fuel ratio correcting device that simplifies and downsizes the air-fuel ratio correcting device, has a wide range of application to air temperatures, is easy to manage, and has excellent followability.

Means for Solving Problem E] The present invention proposes the following automatic air-fuel ratio correction device as a means for achieving the above object.

Pressure detection and temperature detection sensors are attached to the combustion air blast pipe, and based on the input from these sensors, a calculation circuit is used to calculate the ideal pressure (relative to air) of the supplied fuel, and based on this calculated value, An automatic air-fuel ratio correction device configured to control a fuel pressure regulator attached to a fuel supply pipe to correct the ratio of air to fuel.

[Function] In the above device, when detected values are input from the pressure and temperature sensors attached to the combustion air blast pipe,
The calculation circuit performs calculations based on a pre-memorized program, sends a control signal based on this calculation value to the fuel pressure regulator attached to the combustion supply pipe, and adjusts the fuel pressure to achieve the ideal air pressure. It adjusts the fuel ratio.

[Examples and their effects] FIG. 1 shows the concept of a correction device according to the present invention.

1 is a blower, 2 is a blow pipe (air line) leading from the blower l to the burner 3, and 4 is a heat exchanger in a part of the blow pipe 2 for heating (preheating) the blown air using exhaust heat. , 5 is a pressure sensor attached to the downstream side of the heat exchanger 4 in the blast pipe 2, and this pressure sensor 5
A piezoelectric type is used.

Numeral 6 is a temperature sensor attached to the blast pipe 2 in the same way as the pressure sensor 5, and this temperature sensor 6 is of a thermocouple type.

7 is the fuel supply pipe (gas line) leading to burner 3,
A pressure equalizing valve 8 is attached to a part of this fuel supply pipe 7.

9 is an arithmetic circuit, and when the static pressure of the air detected by the pressure sensor 5 and the temperature detected by the temperature sensor 6 are input from the signal lines io and it, it calculates the calculation formula and constant value stored in advance. etc., to calculate the static pressure in fuel supply #-7 to achieve the set air ratio, and control the pressure equalizing valve 8 based on this calculated value. Equalizing valve 8
is a pressure equalizing valve operating pressure pipe 1 which is partially branched from the blast pipe 2;
4, and this pressure is controlled by an actuator in response to a control signal from an arithmetic circuit 9. 14 is an output tube.

FIG. 2 is for explaining the embodiment of the present invention in more detail.

Now, to describe the operation of the embodiment in detail based on this figure, the operation instruction is set to "automatic air ratio correction" on the operation panel 15. The program of the arithmetic circuit 9 requests an instruction to set the air ratio, and if there is an input, it immediately switches to the air ratio calculation program.

The pressure sensor 5 and temperature sensor 6 attached to the air pipe 2 convert the detected values into electrical signals, and the converted electrical signals are sent from the amplifier 1617 to the converters 18 and 19, where they are converted from analog to digital signals. After that, it is input to the arithmetic circuit 9 via the input port 20.

In accordance with the program, the arithmetic circuit 9 immediately calculates the ideal fuel supply pressure for temperature and pressure by comparing it with constants and coefficient items, and outputs the air that is attached to the pressure equalization valve operating pressure pipe 13 via the output boat 21. The line for the actuator with the regulating valve 22 is selected, the output signal is converted from digital to analog type by the converter 23, and after being amplified by the amplifier 24, the actuator 25 is outputted at an electrical signal level that can be operated, and control is performed for the first time. The actuator 25 is driven as a signal to adjust the pressure of the fuel gas.

Note that 26 is a piezoelectric pressure sensor attached to the pressure equalization valve actuating pressure pipe 13, and the pressure signal detected here is also sent to the arithmetic circuit 9 via the amplifier 27, A/D converter 28, and input port 20. is input.

[Effects of the present invention] As described above, the present invention detects the supply pressure and temperature of preheated air by attaching a pressure sensor and a temperature sensor to the air blow pipe, and uses an arithmetic circuit to determine the ideal temperature based on the detected values. The fuel pressure was adjusted by calculating the fuel supply pressure (to air ratio).As a result, the following effects can be expected.

a. Conventional methods using thermal expansion fluid required manual operation techniques such as specifying appropriate positions of governors, valves, etc., but this is not necessary in the case of the present invention.

b. The ideal fuel-to-air ratio can be immediately calculated using the arithmetic circuit, resulting in good responsiveness.

By using a microcomputer in the C0 calculation circuit.

Overall, it can be simplified and quantified, is easy to manage, is accurate, and has fewer failures.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing an embodiment of the present invention, and FIG. 2 is a flow sheet explaining the operation of the embodiment. l...Blower 2...Air blast pipe 3...Burner 4...Heat exchanger 5...Pressure detection sensor 6... ... Temperature detection sensor 7 ... Fuel supply pipe 8 ... Pressure equalization valve 9 ... Arithmetic circuit 10.11 ... Signal line 13 ... Pressure equalization valve operating pressure Pipe 14...Pressure equalization valve control pressure output pipe

Claims (1)

[Claims] Pressure detection and temperature detection sensors are attached to the combustion air blast pipe, and based on the input from these sensors, a calculation circuit is used to calculate the ideal pressure (relative to air) of the supplied fuel, and based on this calculated value, An automatic air-fuel ratio correction device configured to control a fuel pressure regulator attached to a fuel supply pipe to correct the ratio of air to fuel.