JPS5822945A - Valuation apparatus for capability of oxygen sensor - Google Patents

Abstract

PURPOSE:To improve the measuring accuracy, by providing a master sensor near an oxygen sensor and carrying out the feedback control of the air-fuel ratio of test gas basing on a detection signal of the master sensor. CONSTITUTION:Air from an air bomb 3 and gas from a propane bomb 4, are burned by a burner tester 7. Burned gas is supplied by the volume in accordance with opening and shutting of an electromagnetic valve 12 from a propane bomb for control 10 controlling the air-fuel ratio of combustion gas. Produced test gas is introduced into a piping 16 attached an oxygen sensor 1 and a master sensor 19. Detected signal of the sensor 19 is fed back to a triangular wave controlling device 20. An electromagnetic driving circuit 13 is ordered by the device 20 by increasing and decreasing a portion of a direct electric current of a triangular wave signal basing on the detected signal and opening and shutting control of the valve 12 is carried out. A capability valuation apparatus decreased the difference remarkably by this feedback control is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for evaluating (inspecting) the performance of an oxygen sensor, and generally relates to an oxygen sensor that detects oxygen concentration in exhaust gas from an engine, etc., and feeds it back to air-fuel ratio control. requires relatively high-precision detection performance.

For this reason, in the past, F, 1, for example, a device as shown in FIG. The performance of the oxygen sensor 1 is evaluated and determined using a tube, and non-defective products are selected.

2 in the figure is a combustion gas generator, in which the air and propane from the air tank 3 are converted into gas from the pump 4, and the flow rate or pressure control valves 5 and 6 installed in the middle of the piping.
It is supplied in a predetermined amount to the paddle-natester 7, and when ignited by the igniter 8 generates combustion gas.

Burner tester 7KFi, air from control air damper 9 and propane for control are supplied as appropriate via gas from pump 10 or electromagnetic valves 9pH and 12 with linear opening characteristics, respectively. Among these, the solenoid valve 12 (also till) is opened and closed by the solenoid valve drive circuit 13, and its opening/closing time and opening degree are as follows.
It is controlled by a signal from a triangular wave generator 14. Since it is fc, at this time solenoid valve 11 (also Fil 2)
Fi, fully closed, fully open, or kept at a constant opening.

The triangular wave generator 14 outputs a triangular wave signal with a waveform and period T as shown in the left side of FIG. It can be controlled so that it opens as the upper peak value Q increases and becomes fully open at the upper peak value Q.

In the combustion gas of burner tester 7, propane gas (
(or air) is supplied while increasing and decreasing in a triangular waveform with a period of t1 to generate a test gas. This constitutes an air-fuel ratio control device 15't-.

In this case, the test gas is supplied to the central value R (average value of the upper and lower peak values P and Q) of the signal from the triangular wave generator 114, and the above-mentioned flow rate (t or pressure) control valve The opening degree of 5.6 and the opening of the solenoid valve 11 are set.

Then, this test gas is introduced into the tester piping 16,
An oxygen sensor 1 to be inspected is attached on the way.

The oxygen sensor 1 outputs a signal according to the change in the air-fuel ratio of the test gas, and the signal is sent to the data processing device f1117 and the recording device f.
Sent to It18.

In the data processing device 117, the signal station 03 in Fig. 2)
The signal is processed into a waveform as shown in , and the time t of a signal whose output is higher than the average reference value S of the upper peak output and the lower peak output is measured and recognized as data.

On the other hand, this data processing device! At t17, a triangular wave signal (
The prisoner in Figure 2) is input.

Then, the data processing device 17 compares the period T of the triangular wave signal and the signal time t after waveform processing from the oxygen sensor 1, and detects the ratio t/T.

Specifically, the fc average was measured over multiple periods of t/T1r,
The performance of the oxygen sensor 1 is evaluated based on the results.

In this case, the closer it is to t/T or 1/2, the better the product is determined.

However, in this conventional device, the air-fuel ratio of the test gas was controlled by flow rate control or mechanical pressure control of groton gas, etc., making it difficult to set the air-fuel ratio, and setting the air-fuel ratio due to changes in the environment. An error occurs in the air-fuel ratio,
There was a problem in that the error in evaluating the performance of the oxygen sensor became large.

Therefore, the present invention provides a master safety f1i near the oxygen sensor.
By installing and controlling the air-fuel ratio of the test gas based on the detection signal from this master sensor,
The purpose of the present invention is to provide an oxygen sensor performance evaluation device with increased setting precision and significantly reduced measurement errors.

EMBODIMENT OF THE INVENTION Hereinafter, a second embodiment of the present invention will be described based on the drawings.

In Figure 3, 2 is a device that generates combustion gas by burning the air from the air tank 3 and the propane gas J:ki4-tf from the propane gas pipe 4, and the burner tester is 7 yen. In order to increase or decrease the air-fuel ratio of the combustion gas, propane gas from the control propane tank 10 (or control air from the pump 9) is supplied in an amount according to the opening and closing of the solenoid valve 12. I'm trying to make it happen.

The test gas thus generated is introduced into the tester pipe 16 to which the oxygen sensor 1 to be tested is attached. A sensor 19 is installed.

The master sensor 19 detects the air-fuel ratio of the test gas in the same way as the oxygen sensor 1, and feeds back the detection signal to the triangular wave control device 20.

Triangular wave control device 2 (1) outputs a triangular signal sound with a waveform and period T as shown in (4) in Fig. 2, and also increases or decreases the DC component (center value R) of the triangular wave signal by t based on the detection signal. , to the electromagnetic valve drive circuit 13 to control the opening and closing of the electromagnetic valve 12. Accordingly, the air-fuel ratio is set by adjusting the supply amount of the control proton gas, and the air-fuel ratio feedback control means is configured. be done.

Specifically, the detection signal from the master sensor 19 is first processed in the triangular wave control unit 20 into a waveform as shown in (■) in FIG. Then, from the signal after this processing, the signal time to where the output is higher than the average reference value So of the upper peak output and the lower peak output is measured over the past several cycles, and this time 1. For example, the center value R of the triangular wave signal is set so that the time ratio of the period T of the triangular wave signal is always constant (1:2 is good).
t sub-control to open and close the solenoid valve 12.

That is, the triangular wave signal output from the triangular wave control device 120 relatively increases or decreases based on the detection signal of the master sensor 19 to control the air-fuel ratio. The fuel ratio is maintained at a constant level, and the air-fuel ratio is evenly increased or decreased at regular intervals in accordance with the triangular wave signal, with the stoichiometric air-fuel ratio as the boundary.

As a result, it is possible to always supply the test gas with the set air-fuel ratio.

Note that the detection signal of the oxygen sensor i to be tested is sent to the data processing device 1 together with the triangular wave signal from the triangular wave control device @20.
17 and a recording device 18, and the performance is evaluated in the same manner as in the conventional example.

In this way, in this embodiment, the master sensor 19t is installed near the oxygen sensor 1 to be tested, and the air-fuel ratio of the test gas is feedback-controlled based on the detection signal from the master sensor 19. Therefore, the air-fuel ratio can be set accurately and easily, and even if the environment or atmosphere changes, the air-fuel ratio will not go out of order.The performance of oxygen sensor 1 can be evaluated with extremely high accuracy, and it can be used as an inspection load. reliability is significantly improved.

Furthermore, even if the flow rate settings of the combustion gas generator &2 for the gas and air are not very accurate, this can be compensated for, the influence of which is eliminated, and the setup of the equipment is simplified. Simplified.

As explained above, according to the present invention, a master sensor is installed near the oxygen sensor to be tested, and the air-fuel ratio of the test gas is feedback-controlled based on the detection signal of the master sensor. This has the advantage that the air-fuel ratio can be obtained and the performance of the oxygen sensor can be evaluated accurately.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a conventional device, Fig. 2 is a graph showing an AJFi triangular wave signal, Fig. 2 (6) is a graph showing a waveform-processed output signal of an oxygen sensor, and Fig. 3 is an embodiment of the present invention. It is a configuration diagram showing 1. Oxygen sensor, 2. Combustion gas generation amount, 3.
··air? Power, 4... Propane, power, 5.6...
・Flow rate or pressure control valve, 7.../4-Na tester, 8
...Ignition device, 9...Control air generator, lO・-
・Control armrest, 11.12...Solenoid valve,
13... Solenoid valve drive circuit, 14... Triangular wave generator, 15... Air-fuel ratio control device, 16... Tester piping,
17...Data processing device, 1 g-...Recording device, 1
9... Master sensor, 20... Triangular wave control device. Patent applicant Nippon Motor Co., Ltd.

Claims (1)

[Claims] 1. A combustion gas generator and an air-fuel ratio control device that increases or decreases the air-fuel ratio of the gas at regular intervals generate test gas for the oxygen sensor to be inspected, and adjust the air-fuel ratio. In a device that evaluates the performance of an oxygen sensor by inputting a sensor signal tube output according to a data processing device and a recording device, a master sensor is provided near the oxygen sensor, and a test is performed based on the detection signal of this master sensor. An oxygen sensor performance evaluation device characterized by having a means for feedback controlling the air-fuel ratio of gas. 2. The control means is a device for determining the time kfillJ during which the detection signal of the master sensor is higher than the average reference value, and controlling the air-fuel ratio so that this time becomes a constant ratio with respect to a certain time period. The oxygen sensor performance evaluation device according to scope 1.