JPS626183B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an oxygen concentration detector testing device for testing the voltage output from an oxygen concentration detector provided in the exhaust system of an internal combustion engine.

[Prior art] An oxygen concentration detector is installed in the exhaust system of an automobile engine, etc., and the mixture ratio of fuel supplied to the engine is measured based on this signal, and the fuel supply to the intake system is controlled to maintain a predetermined air-fuel ratio. A system is known that efficiently purifies exhaust gas using a catalyst device provided in the system.

In this system, the detection accuracy of the oxygen concentration detector has a major impact on exhaust gas purification, and testing equipment is required to check whether the oxygen concentration detector is accurately detecting the oxygen concentration. .

This is especially required to be easy to use in general service factories, etc.
Conventionally, oscilloscopes etc. have been used, but they are large and
It was expensive and complicated to handle, requiring specialized knowledge, and was not suitable for use in the general market.

For this reason, an inspection device has been devised that uses a microcomputer or the like to make the inspection device compact and easy to handle, and that can be easily installed in a vehicle. This inspection device constantly diagnoses the oxygen concentration detector, and when a defect occurs due to deterioration or the like of the oxygen concentration detector, a warning device or the like is used to notify the passenger.

However, if the reaction of the oxygen concentration detector is delayed due to deterioration etc., it can be determined that it is defective, but if there is always a certain difference between the output of this oxygen concentration detector and the signal corresponding to the actual oxygen concentration, Even if the actual oxygen concentration is dilute, a signal indicating a high concentration is output may lead to a false diagnosis.

[Problems to be Solved by the Invention] Taking these facts into consideration, the present invention provides an oxygen concentration detector that can easily and accurately determine the quality of an oxygen concentration detector and that can be easily installed in automobiles. The present invention provides an inspection device.

[Means for solving the problem] The oxygen concentration detector inspection device according to the present invention controls the amount of fuel supplied to the intake system by comparing the input voltage with a reference voltage corresponding to an appropriate oxygen concentration. An oxygen concentration detector inspection device for inspecting an oxygen concentration detector that inputs a voltage that changes according to the oxygen concentration of an exhaust system to an oxygen concentration control device, comprising: a voltmeter for indicating an output voltage of the oxygen concentration detector; a comparator that compares the output voltage of the oxygen concentration detector with a reference voltage; a display that displays the output of the comparator; and a voltage that is higher or lower than the reference voltage and is sent to the oxygen concentration control device. and a signal generator for inputting the signal.

[Function] The voltage detected by the oxygen concentration detector is input to the comparator and voltmeter. The comparator compares this detection voltage with the reference voltage and outputs a low-level or high-level signal depending on whether the oxygen concentration is dilute or concentrated and displays this on the display, making it easy to operate the oxygen concentration detector. You can check the status. Furthermore, the voltmeter can directly indicate the detected voltage in detail, making it easy to measure the oxygen concentration in the exhaust system.

Further, in the present invention, by inputting voltages whose values are determined in advance (voltages higher and lower than the reference voltage) to the control device using the signal generating device,
The output voltage value from the signal generator can be compared with the indication from the voltmeter, and it can be determined whether the oxygen concentration detector is operating normally or not based on changes in the display on the comparator.

[Example] An example in which the present invention is applied to an automobile engine will be described below with reference to the drawings.

In FIG. 1, an intake system 11 of an engine 10 is provided with a fuel injection valve 12 to supply a necessary amount of fuel to the engine 10, and an exhaust system 1
3 is opened to the atmosphere via a catalyst device 14 to purify exhaust gas.

In addition, the exhaust system 13 includes an engine 10 and a catalyst device 1.
An oxygen concentration detector 15 whose output voltage is increased in proportion to the oxygen concentration is provided between the oxygen concentration detector 15 and the oxygen concentration detector 15 and connected to the oxygen concentration control device 16, which is connected to the injection valve 12. As a result, a signal is sent to the injection valve 12 in order to correct the fuel supplied to the engine 10 to an appropriate value based on the oxygen concentration detected by the oxygen concentration detector 15.

Here, an inspection device 25 consisting of a voltmeter 21, a comparator 22, a lamp 23, and a signal generator 24 is connected to an oxygen concentration detector 15 and a control device 16 to display the oxygen concentration as well as to control the oxygen concentration detector 15 and control device. Diagnosis is performed by determining whether the device 16 is good or bad.

One end of this voltmeter 21 is grounded, and the other end is connected to the output side of an amplifier 27 via a resistor 26, and the + side input terminal of this amplifier 27 is connected to the oxygen concentration detector 15 via a resistor 28. connected to. Further, the negative terminal of this amplifier 27 is connected to the output terminal.

This causes the voltmeter 21 to indicate a voltage proportional to the oxygen concentration in the exhaust system 13 detected by the oxygen concentration detector 15.

The comparator 22 is provided with a differential amplifier 31, and the output terminal of the differential amplifier 31 is connected to a resistor 3.
The positive input terminal is connected to the oxygen concentration detector 15 via a resistor 34. Further, a constant voltage corresponding to the optimum oxygen concentration in the exhaust system is applied to the negative input terminal of the differential amplifier 31, and this constant voltage is applied to the constant voltage diode 3.
5 and resistors 36, 37, 38 connected in series. That is, one end of the resistor 36 is connected to the battery 39,
One end of the resistor 38 is grounded, one end of the voltage regulator diode 35 is connected to the intermediate connection point between the resistors 36 and 37, and the other end is connected to the ground.
The intermediate connection point of 8 is connected to the negative input terminal of the differential amplifier 31.

Further, one end of the lamp 23 is connected to a battery 39.
, the other end is connected to the transistor 3 via the resistor 41.
The transistor 33 is connected to the collector terminal of the transistor 33.
The emitter terminal of is grounded.

With this configuration, the detection voltage corresponding to the oxygen concentration in the exhaust system 13 detected by the oxygen concentration detector 15 is detected by the constant voltage diode 35.
If the voltage is higher than the reference voltage determined by , the transistor 33 is turned on and the lamp 23
It is designed to light up. In other words, if the detected oxygen concentration is higher than the optimum value, the lamp 23 is turned on, and the exhaust system 13 is turned on.
Since the oxygen concentration in the exhaust system is controlled by the control device 16, the oxygen concentration in the exhaust system is normally diluted and overconcentrated repeatedly at a frequency of 1 to 2 Hz.
3 will also continue to blink.

It is possible to visually detect that the supplied air-fuel mixture has been appropriately corrected by blinking the lamp 23, but it is of course possible to use an indicator such as a light emitting diode or liquid crystal instead of the lamp 23. It is. In addition to the blinking of the lamp 23, if you want to know the voltage value in more detail, use the voltmeter 2.
With the instruction 1, the output of the oxygen concentration detector 15 can be reliably read. Further, by using the voltmeter 21 in combination, it is also possible to detect abnormal lighting caused by disconnection of the connector of the oxygen concentration detector 15 or the like.

Next, the signal generator 24 has a movable contact 43 and a fixed contact 4 connected to the control device 16, respectively.
By connecting the movable contact 43 to one or the other of the fixed contacts 44 and 45, it is possible to apply a voltage corresponding to excessive concentration or dilution of the exhaust system oxygen concentration to the control device 16, respectively. I'm starting to be able to do it. That is, regardless of the output of the oxygen concentration detector 15, the control device 16 controls the amount of fuel injected by the injection valve 12 according to the output voltage from the signal generator 24.

Here, the voltage indicated to the voltmeter 21 by the voltage output from the signal generator 24 is determined in advance, and the voltage output from the signal generator 24 and the voltage indicated by the voltmeter from the oxygen concentration detector 15 are determined in advance. Oxygen concentration detector 1
5 is operating normally.

Further, when a signal indicating that the oxygen concentration is high is sent from the signal generating device 24 to the control device, the control device controls the fuel injection amount, and the oxygen concentration in the exhaust system becomes lean. Here, if the lamp 23 goes out, it can be determined that the oxygen concentration detector is a good product.

In this way, the inspection device 25 has been made compact and easy to handle, so it can be mounted on a vehicle, and when determining the quality of the oxygen concentration detector 15, it can be used in conjunction with other inspection devices at a maintenance shop, etc. There is no need to prepare etc. Further, by using the signal generator, it is possible to easily determine whether the oxygen concentration detector 15 is good or bad in a short time, and the reliability of air-fuel ratio control is increased.

Next, the embodiment shown in FIG. 2 is obtained by adding a counter 50 to the above embodiment, one input terminal of the counter 50 is connected to the output terminal of the comparator 22, and the other input terminal is connected to the output terminal of the comparator 22. It is connected to stable multi 51. Further, the output terminal of the counter 50 is connected via a driver 52 to a display section 52 including a 7-segment display element.

As a result, the counter 50 is
The frequency generated by the oxygen concentration detector 15 during the gate open time is counted by the gate signal and displayed on the display section 53. Here, when the oxygen concentration detector 15 deteriorates, its responsiveness decreases (referred to as the Z characteristic of the response), so the degree of deterioration can be determined based on the magnitude of the counted frequency. Here, since the responsiveness of the oxygen concentration detector 15 changes depending on the ambient temperature, it is preferable to determine the temperature at the time of measurement and measure the degree of deterioration.

In addition to the configuration of the present invention, FIG. 3 shows a voltmeter 2.
1. A signal generator 60 that applies a simulated signal to the lamp 23 is provided, and this signal generator 60
is a movable contact 61 similar to the signal generator 24,
Consisting of fixed contacts 62 and 63, the movable contact 61 is connected to the + side input terminal of the amplifier 27, the fixed contact 62 is connected to the intermediate connection point between the lamp 23 and the battery 39 via a resistor 64, and the fixed contact 63 is connected to the + side input terminal of the amplifier 27. It is grounded. Although not shown, the amplifier 27 is connected to the oxygen concentration detector 15 as in FIGS. 1 and 2.

With this configuration, by connecting the contacts 61 and 63, the input potential of the amplifier 27 and the differential amplifier 31 is set to the installation potential, the reading on the voltmeter 21 is zero, the lamp 23 is turned off, and the contacts 61 and 62 are connected. On the contrary, when the connection is made, the indication on the voltmeter 21 fluctuates greatly and the lamp 23 lights up. Therefore, by operating the signal generator 60, the voltmeter 21, lamp 23
It becomes possible to diagnose. In fact, it is preferable that this diagnosis be performed before performing the oxygen concentration display and diagnosis shown in FIGS. 1 and 2.

[Effects of the Invention] As explained above, in the oxygen concentration detector testing device according to the present invention, predetermined voltages higher and lower than the reference voltage can be selected from the signal generator and input to the control device. The output value of the oxygen concentration detector can be easily and accurately diagnosed by comparing the true output value calculated according to the output value of the oxygen concentration detector with the output of the oxygen concentration detector.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the oxygen concentration detector testing device according to the present invention, Fig. 2 is a circuit diagram showing another embodiment, and Fig. 3 is a circuit diagram showing a predetermined signal input to a voltmeter and a comparator. It is a circuit diagram when a signal generator is added. 10...Engine, 13...Exhaust system, 15...
Oxygen concentration detector, 16...Oxygen concentration control device, 2
1... Voltmeter, 22... Comparator, 23... Lamp, 24... Signal generator, 50... Counter,
60...Signal generator.

Claims (1)

[Claims] 1 Oxygen concentration input voltage that changes according to the oxygen concentration in the exhaust system to the oxygen concentration control device that controls the amount of fuel supplied to the intake system by comparing the input voltage with a reference voltage corresponding to the appropriate oxygen concentration An oxygen concentration detector testing device for testing a detector, comprising: a voltmeter that indicates the output voltage of the oxygen concentration detector; a comparator that compares the output voltage of the oxygen concentration detector with a reference voltage; and this comparator. An oxygen concentration detector testing device comprising: a display that displays the output of the oxygen concentration detector; and a signal generator that selects a voltage higher or lower than the reference voltage and inputs the selected voltage to the oxygen concentration control device.