JPH0454414A - Air/fuel ratio measuring instrument - Google Patents

Abstract

PURPOSE:To measure the flow rate in a main flow passage with high accuracy and to shorten the setting and stabilization time of the flow rate by setting the flow rate continuously by an acoustic velocity nozzle which has variable sectional area. CONSTITUTION:Target values of suction negative pressure and a flow rate are inputted to a personal computer 12. The maximum flow rate of air flowing through the acoustic velocity nozzle 4 is calculated from them to calculate the current sectional area of the acoustic velocity nozzle 4. Consequently, the movement distance of a valve 5 is calculated to output the number of driving pulses of an actuator 6. Consequently, the valve 5 moves and the current sectional area of the acoustic velocity nozzle 4 varies to vary the air flow rate. The suction negative pressure also varies correspondingly, but a throttle valve is controlled by an actuator 7 so that the suction negative pressure reach the target value; when the target value is reached, data on the suction negative pressure, the movement distance of the value, and a fuel flow are inputted, sent to the personal computer, and printed out.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is applicable to a device for measuring the air-fuel ratio of an air-fuel ratio control device. Since air flow rate can be measured continuously, measurement time is shortened and it is suitable for mass production measurement.

[Conventional technology]

Conventional devices combine multi-stage sonic nozzles with different flow cross-sectional areas to set the maximum air flow rate. In this method, the flow rate is set in steps according to the flow rate of the sonic nozzle with the minimum cross-sectional area. Furthermore, it is not possible to measure the characteristics of the air-fuel ratio control device by changing the flow rate continuously from zero to the maximum flow rate. Furthermore, since multiple nozzles are switched, it takes time for the main flow amount to stabilize.

Incidentally, related devices of this type include, for example, Japanese Utility Model Application No. 56-41210 and Japanese Utility Model Application No. 61-119721.

[Problem to be solved by the invention]

1. Conventionally, when measuring the air flow rate of an air-fuel ratio control device,
Multiple stages of sonic nozzles were prepared, and the maximum flow rate was determined by their combination. This means that the air flow rate changes step by step in increments of the smallest nozzle and cannot be changed steplessly. Therefore, the aim is to change the air flow rate steplessly using a variable cross-sectional area sonic nozzle.

2. The purpose is to continuously measure the air-fuel ratio of an air-fuel ratio control device by changing the air flow rate steplessly using a variable cross-sectional area sonic nozzle.

[Means to solve the problem]

In order to achieve the above object, a variable cross-sectional area sonic nozzle is provided in the flow path of the air-fuel ratio control device, and the air flow rate is controlled by changing the cross-sectional area of the nozzle.

In order to control the air flow rate steplessly, a target value is set in minute increments, and the cross-sectional area of the variable cross-sectional area sonic nozzle is changed according to the target value.

[Effect]

Variable cross-sectional area sonic nozzles change the flow cross-sectional area to change the air flow rate in the flow path.

The actuator moves the valve of the variable cross-sectional area sonic nozzle in the axial direction, thereby changing the flow cross-sectional area of the sonic nozzle.

The microcomputer controls the position of the valve via an actuator to change the flow cross-sectional area of the sonic nozzle, thereby changing the maximum air flow rate through the sonic nozzle. Furthermore, the throttle valve of the air-fuel ratio control device is controlled to set the suction negative pressure to a target value. Additionally, the valve position, pressure upstream of the sonic nozzle, and fuel flow rate are measured and transferred to a computer.

The personal computer inputs approximate values of air flow rate and suction negative pressure, and sets control target values through interpolation calculations. The target value is transferred to the microcomputer and measured. It receives the measurement results from the microcomputer, calculates the air-fuel ratio, and displays the results as well as a graph.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. 1 indicates the main channel through which air flows. 2 is a vacuum pump for flowing air into the main flow path 1; 3 is an object to be measured (vaporizer). 4 is a sonic nozzle provided in the main flow path 1. The flow cross-sectional area of the sonic nozzle is determined based on the required maximum flow rate.

5 is a valve that changes the flow cross-sectional area of the sonic nozzle 2.

The valve 5 has a conical shape, is installed coaxially with the sonic nozzle 4, and changes the flow cross-sectional area of the sonic nozzle 4 by moving in the axial direction. The taper of the valve 5 takes into consideration the change in the flow cross-sectional area of the sonic nozzle 4 with respect to the moving distance of the valve 5. 6 is an actuator 1 that moves the valve 5. 7 is an actuator 2 that moves the throttle valve of the object to be measured 3
It is. Reference numeral 8 denotes a position/lateral ratio sensor for detecting the position of the valve 5, which detects the moving distance of the valve 5 with reference to the fully closed state of the sonic nozzle 4. 9 is a pressure sensor that detects the upstream pressure of the sonic nozzle 2. 10 is a fuel flow meter that measures the fuel flow rate of the object 3 to be measured. 11 is a microcomputer that controls the throttle valve and valve 5 and measures the upstream pressure fuel flow rate of the sonic nozzle 4 and the distance traveled by the valve. 12 is a personal computer for inputting target values (inhalation negative pressure, air flow rate) and displaying measurement results.

The procedure for determining the air-fuel ratio of the object to be measured 3 is as follows, and the flowchart I~ is shown in FIG.

Enter 20 target values for suction negative pressure and air flow rate into the computer 12. Interpolate the target value and obtain data for 300 measurement points. Calculate the maximum air flow rate through the sonic nozzle from the suction negative pressure and air flow rate. Calculate the flow cross-sectional area of the sonic nozzle from the maximum air flow rate6Furthermore, calculate the travel distance of the valve from the flow cross-sectional area. Determine the number of actuator drive pulses from the distance traveled by the valve.

Transfer the target value of suction negative pressure and the number of actuator drive pulses from the computer to the microcontroller.

The microcomputer outputs the given number of pulses to the actuator. This causes the valve to move, changing the flow cross-sectional area of the sonic nozzle and changing the air flow rate.

Since the suction negative pressure also changes as the air flow rate changes, the actuator is driven and the throttle valve is controlled so that the suction negative pressure matches the target value. When the suction negative pressure reaches the target value, data on the suction negative pressure, valve travel distance, and fuel flow rate are captured.

After measuring 300 points.

Data on suction negative pressure, valve travel distance, and fuel flow rate are transferred to a computer.

The computer calculates the air flow rate and air-fuel ratio based on the transferred data. The calculation results are output to a printer and plotter.

According to this embodiment, since the amount of change in the ventilation flow rate of the sonic nozzle can be set steplessly by changing the number of measurement points, the flow rate in the main flow path can be measured with high accuracy.

Furthermore, since the flow rate can be set continuously, the stabilization time of the flow path is shortened.

〔Effect of the invention〕

According to the present invention, since the flow rate can be set steplessly using the variable cross-sectional area sonic nozzle, the flow rate in the main flow path can be measured with high accuracy.

Furthermore, since the flow rate of the variable cross-sectional area sonic nozzle can be continuously controlled, an air-fuel ratio measuring device can be provided in which the flow rate setting and stabilization time are shortened.

[Brief explanation of drawings]

FIG. 1 is a system configuration diagram of an embodiment of the present invention, FIG. 2 is a control flowchart of the personal computer and microcomputer shown in FIG. 1, and FIG. 3 is a diagram showing the measurement results of the air-fuel ratio. DESCRIPTION OF SYMBOLS 1...Main flow path, 2...Vacuum pump, 3...Measurement object, 4...Sonic nozzle, 5...Valve, 6...Actuator 1.7...Actuator 2.8・position Detection sensor, 1o... fuel flow meter, 11... microcomputer,
12...PC, 13...Printer, plotter,
14...Fuel supply device.

Claims (1)

[Claims] 1. Air flow rate is controlled by a variable cross-sectional area sonic nozzle provided in the main flow path, a valve that controls the flow cross-sectional area of this nozzle, and the air flow rate is measured from the position of the valve. An air-fuel ratio measuring device characterized by: 2. The air-fuel ratio measuring device according to claim 1, wherein the air-fuel ratio measuring device continuously controls the air flow rate by minutely changing the flow cross-sectional area of the variable cross-sectional area sonic nozzle. 3. The air-fuel ratio measuring device according to claim 2, characterized in that the air-fuel ratio is continuously measured by measuring the fuel flow rate with respect to the continuously changing air flow rate.