JPH01114733A - Automatic certificating device for internal cylinder pressure sensor - Google Patents

Abstract

PURPOSE:To replace a sensor by holding in advance the maximum value of the cylinder internal pressure in which the boost and the speed of revolution of an engine are preliminarily made parameters, in a map, calibrating the cylinder internal pressure whenever the engine is started, and deciding when the deviation exceeds a prescribed value. CONSTITUTION:A cylinder internal pressure sensor 2, and a suction negative pressure sensor 4 are provided on each cylinder of an engine body 1, and a suction manifold 3, respectively, and connected to an electronic control unit 9 through a charge amplifier 8 together with a crank angle sensor 5, etc. provided on the body 1. Also, a map is constituted by storing the maximum cylinder internal pressure value Pmax which is derived in advance by setting the speed of revolution of an engine and suction negative pressure at the time of flanking as parameters, in a memory of the unit 9. In such a state, whenever the engine is started, a calibration of the cylinder internal pressure sensor is executed from a comparison with Pmax, and when a deviation of a calibration coefficient obtained from a statistical calculating means has exceeded, a replacement time of the sensor is informed.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an automatic verification device for a cylinder pressure sensor.

[Conventional technology]

When performing engine operation control such as ignition timing control, fuel injection amount control, intake air amount control, etc. One known method for obtaining this information is, for example, as disclosed in Japanese Patent Application Laid-Open No. 59-136634, in which a cylinder pressure sensor is provided in each cylinder of an engine. However, since the cylinder pressure sensor described above is subject to deterioration over time due to being placed under harsh conditions, the sensor output must be constantly calibrated. For this reason, for example, a calibrating device for a cylinder pressure sensor has been proposed, as disclosed in Japanese Patent Laid-Open No. 59-193326.

[Problems to be Solved by the Invention] However, even if the output value of the cylinder pressure sensor is corrected using the above calibration device, if the deterioration over time becomes significant or if a failure occurs, the cylinder pressure sensor must be replaced. However, the above-mentioned calibration device cannot determine at what point it should be replaced. Note that the method described in Japanese Patent Application Laid-Open No. 58-5628 is for determining the stability of the engine from the cylinder pressure, and is not for determining and displaying changes over time, abnormalities, etc. of the cylinder pressure sensor itself. do not have. Therefore, the present invention sets the degree of calibration at each engine start, without taking into account the deterioration of the cylinder pressure sensor over time, and issues an alarm when the deviation of the calibration exceeds a predetermined value. The present invention attempts to provide an automatic verification device for a cylinder pressure sensor that indicates when it is time to replace the internal pressure sensor. [Means for Solving the Problems] Therefore, in the present invention, the maximum cylinder pressure value P 1 lax with intake negative pressure and engine speed as parameters is stored in a memory to form a map, and the cylinder pressure sensor is Maximum output value VI! means for detecting laX before the first explosion when starting the engine; means for determining the maximum cylinder pressure PnaX from the map from the intake negative pressure and engine rotational speed at the time of detection by the detection means; and cylinder pressure from PlaX and V lax. The sensor includes means for determining a calibration coefficient of the sensor and means for issuing an abnormality alarm when the deviation of the calibration coefficient exceeds a predetermined value.

[For production]

Therefore, by setting a calibration coefficient each time the engine is started, not only can the cylinder pressure sensor be calibrated, but also when the difference in the calibration coefficient exceeds a predetermined value, the cylinder pressure sensor has reached its end of life. Alternatively, it is possible to determine that a failure has occurred and issue an abnormality alarm to indicate that it is time to replace the cylinder pressure sensor.

【Example】

Hereinafter, one embodiment of the present invention will be specifically described with reference to the drawings. In the figure, reference numeral 1 is an engine main body, and a cylinder pressure sensor 2 is installed in each cylinder. Further, an intake negative pressure sensor 4 is provided at the base end of the intake manifold 3. Further, a crank angle (rotation) sensor 5 is installed in the engine body 1, and if necessary, an atmospheric pressure sensor 6, an intake air temperature sensor 7, etc. are also installed. The output signals of the respective detection means are supplied to the electronic control unit 9 via the charge amplifier 8, and from the control unit 9, the fuel injection valves 10. Control signals are given to required locations such as the idle speed control valve 11. In particular, regarding the automatic verification of the cylinder pressure sensor, the memory in the control unit 9 is configured in advance with a map of the internal maximum pressure 1iiPmax determined using the engine speed during cranking and the intake negative pressure as parameters (3rd
(see figure) and memorize it. The control unit 9 also includes a motoring detection means 91 for detecting the maximum output value VIax of the cylinder pressure sensor 2 before the first pitch when starting the engine. When the motoring detecting means 91 obtains the detected value Vnax, a map reference means 92 calculates the cylinder pressure maximum value P IaX from the map from the intake negative pressure and engine rotational speed at that time. P nax/V 1 from the above PlaX and V l1aX
Coefficient setting means 93 for calculating the calibration coefficient of the cylinder pressure sensor 2 by calculating 1a×. Means 94 for storing the output value as data. Statistical calculation means 95 for calculating the standard deviation from the data in the data storage means. When the accumulated amount of data exceeds a predetermined value and the deviation of the output value at that time exceeds a predetermined value with respect to the standard deviation, an alarm display means 96 is provided that displays %irl@, The coefficient setting means 93
The output value of is given to the control circuit 97. In such a configuration, the cylinder pressure sensor 2 is calibrated in the control unit 1-9 using a routine as shown in FIG. That is, step 51
In 01, it is determined whether the engine has been started or not, or before the first explosion of the engine (this is
By not igniting for a given cycle,
), the process moves to step 5102 and the engine rotational speed at that time is determined. Next, in step 5103, a boost is detected, and in step 51
Move to 04. Here, the maximum cylinder pressure P n corresponding to the engine speed and boost is determined by the map reference means 92.
Find ax. Next, in step 5105, the maximum output value Vl'la× obtained from the cylinder pressure sensor 2 is taken in, and in step 8106, the coefficient setting means 93 sets P ma
Calculate x/v nax to find the calibration coefficient of the cylinder pressure sensor. The calibration coefficient is used for calibrating the cylinder pressure sensor during subsequent cranking. Then, in step 5107, the calibration coefficient is
The data is stored in the data storage means 94. Step 31
In 08, the statistical calculation means 95 calculates an average value as a standard deviation from the accumulated data. and,
In step 5109, it is determined whether or not the amount of accumulated data exceeds a predetermined value. If it exceeds the predetermined value, in step 5110, the standard deviation is compared with the output value of the coefficient setting means 93 at that time. , if it exceeds the predetermined value, the process moves to step 5111, and the VM display means 96 displays,
This indicates that the cylinder pressure sensor 2 is due for replacement. Note that if it is determined in step 5101 that cranking is in progress (after the first explosion), the process returns without going through the above routine. Incidentally, the output value of the cylinder pressure sensor may be corrected based on atmospheric pressure or temperature by inserting an appropriate step between steps 5104 and 8105, and performing correction on the output value from the map.

【Effect of the invention】

The present invention has been described in detail above, and the maximum cylinder pressure value determined in advance using the booth 1 and engine speed as parameters is stored in a map, and each time the engine is started,
The cylinder pressure sensor is calibrated by comparing it with the maximum output value indicated by the cylinder pressure sensor at that time to obtain the value to be calibrated. We caught it as a deviation and started issuing an abnormality alarm from now on, so when the deterioration over time becomes significant,
Alternatively, when an abnormality is detected, the driver can be automatically notified that it should be replaced.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing one embodiment of the present invention, Fig. 2 is a professional diagram showing the internal configuration of the electronic control unit, Fig. 3 is a graph showing specifications for the configuration of the map, and Fig. 4 is a diagram showing the internal configuration of the electronic control unit. It is a flowchart for verification of a cylinder pressure sensor. 2... Cylinder pressure sensor, 4... Suction negative pressure sensor, 5...
...Crank angle sensor, 9...Electronic control unit, 9
DESCRIPTION OF SYMBOLS 1... Motoring detection means, 92... Map reference means, 93... Coefficient setting means, 94... Data storage means, 95... Statistical calculation means, 96... Alarm display means, 97...For control circuits Patent attorney Murai
Figure 2

Claims (1)

[Claims] A means for configuring a map by storing a maximum cylinder pressure value Pmax using intake negative pressure and engine rotational speed as parameters in a memory, and detecting a maximum output value Vmax of a cylinder pressure sensor before the first explosion upon starting the engine; At the time of detection by the means, means for determining the maximum cylinder pressure Pmax from the map from the intake negative pressure and engine rotational speed at that time, means for determining a calibration coefficient of the cylinder pressure sensor from Pmax and Vmax, and a deviation of the calibration coefficient to a predetermined value. An automatic verification device for a cylinder pressure sensor, characterized in that it is equipped with means for issuing an abnormality alarm when the pressure exceeds the limit.