JP2015075019A - Engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine control device which accurately determines whether or not abnormality combustion inhibitory control is necessary without using an in-cylinder pressure sensor.SOLUTION: An engine control device calculates: estimated maximum combustion pressure on the basis of a detection signal of a knock sensor when the same is larger than a predetermined value (Step S12); and a distribution of the estimated maximum combustion pressure (Step S14). The engine control device also learns a distribution pattern of the estimated maximum combustion pressure (Step S15). Then, the engine control device calculates cumulative combustion pressure of a plurality of estimated maximum combustion pressure on the basis of the distribution pattern of the estimated maximum combustion pressure and determines whether or not abnormality combustion inhibitory control is necessary on the basis of the cumulative combustion pressure.

Description

  The present invention relates to an engine control device that determines whether or not abnormal combustion suppression control is necessary.

  When it is determined that abnormal combustion such as knocking adversely affects the durability of the engine, the engine control device starts abnormal combustion suppression control that is control for suppressing abnormal combustion. The engine control device described in Patent Document 1 calculates a regression line from the maximum in-cylinder pressure data for a certain number of days in the past, and determines the occurrence frequency of the in-cylinder pressure that deviates from the threshold line set based on this regression line. Based on this, a sign of abnormal combustion is determined.

JP 2009-203882 A

  The engine control device of Patent Document 1 detects the maximum pressure in the cylinder using an in-cylinder pressure sensor that is an in-cylinder pressure detector. In general, the in-cylinder pressure sensor is expensive because it has a configuration for detecting pressure in a high temperature and high pressure environment.

  An object of the present invention is to provide an engine control device that accurately determines whether or not abnormal combustion suppression control is necessary without using an in-cylinder pressure sensor.

  One form of this engine control apparatus has the following matters. An engine control device for an engine including a knock sensor, wherein the engine control device calculates an estimated maximum combustion pressure based on a detection signal of the knock sensor, and based on the estimated maximum combustion pressure, A pressure distribution is calculated, a cumulative combustion pressure of the plurality of estimated maximum combustion pressures is calculated based on the estimated maximum combustion pressure distribution, and the necessity of abnormal combustion suppression control is determined based on the cumulative combustion pressure.

  According to this engine control apparatus, the cumulative combustion pressure is calculated based on the estimated maximum combustion pressure distribution of the estimated maximum combustion pressure calculated based on the detection signal of the knock sensor. For this reason, even if the distribution shape of the estimated maximum combustion pressure distribution changes, the cumulative combustion pressure corresponding to the changed distribution shape can be calculated. For this reason, even when the environment in which the engine is used is different or when the engine characteristics fluctuate, the necessity of the abnormal combustion suppression control can be accurately determined without using the in-cylinder pressure sensor.

The block diagram of the vehicle of an embodiment. The graph which shows the relationship between the crank rotation angle and combustion pressure of embodiment. The accumulation combustion pressure optimization processing flowchart of an embodiment. (A) The histogram which shows an example of the estimated maximum combustion pressure distribution of embodiment. (B) A histogram showing another example of the estimated maximum combustion pressure distribution.

The block configuration of the vehicle 1 will be described with reference to FIG.
The vehicle 1 includes an engine 10 and an engine control device 20 that controls the engine 10 in an integrated manner. The engine 10 has a knock sensor 11.

  The engine control device 20 outputs various control signals for controlling the fuel injection, the intake air amount, the ignition timing, and the like of the engine 10 to the engine 10. Knock sensor 11 outputs a detection signal that changes according to the magnitude of vibration generated by engine 10 to engine control device 20.

  When abnormal combustion occurs in the engine 10, the combustion pressure in the cylinder becomes excessively high. If abnormal combustion continues, the durability of parts such as the piston and piston ring of the engine 10 may be adversely affected. For this reason, the engine control device 20 determines whether or not abnormal combustion with an excessively high combustion pressure in the cylinder is continued, and when it is determined that the combustion is continuing, starts the abnormal combustion suppression control. As an example of this control, the engine control device 20 starts control with the ignition timing changed.

The calculation of the estimated maximum combustion pressure when abnormal combustion occurs will be described with reference to FIG.
The engine control device 20 calculates the estimated maximum combustion pressure based on the detection signal of the knock sensor 11.

  Knock sensor 11 has a non-saturated operating region and a saturated operating region. Knock sensor 11 outputs a detection signal that changes in accordance with the magnitude of vibration generated by engine 10 in the non-saturated operation region. When the vibration of the engine 10 exceeds the detection limit, the knock sensor 11 becomes a saturated operation region, and the magnitude of the detection signal is saturated.

  As the combustion pressure due to abnormal combustion increases and the fluctuation of the combustion pressure increases, the vibration of the engine 10 increases. Therefore, it is estimated that the longer the period in which the vibration of the engine 10 exceeds the detection limit of the knock sensor 11 and the magnitude of the detection signal is saturated, the greater the maximum value of the combustion pressure caused by abnormal combustion, that is, the maximum combustion pressure. it can.

  The first rotation angle θ1 and the second rotation angle θ2 in FIG. 2 are crank rotation angles at which the detection output of the knock sensor 11 becomes the upper limit of the unsaturated operation region. The engine control device 20 calculates a maximum estimated combustion pressure that is an estimated value of the maximum combustion pressure based on the first rotation angle θ1 and the second rotation angle θ2.

  For example, the engine control device 20 estimates an increase curve of the combustion pressure based on the length of a period from when the vibration detection of the knock sensor 11 starts until the crank rotation angle reaches the first rotation angle θ1, and the crank rotation angle is A downward curve of the combustion pressure is estimated based on the length of the period from when the two rotation angles θ2 are reached until the end of vibration detection. Then, as shown in FIG. 2, the transition of the combustion pressure during the period in which the detection signal from the first rotation angle θ1 to the second rotation angle θ2 is saturated is extended until these ascending and descending curves cross each other. And the estimated combustion pressure (dotted line in FIG. 2) in the saturation operation region of the knock sensor 11 is calculated. The estimated maximum combustion pressure is the maximum value of the estimated combustion pressure thus calculated by the engine control device 20.

  In the case where the above ascending curve and descending curve are obtained in advance, the saturation operation region of the knock sensor 11 is determined only from the time until the crank rotation angle reaches the second rotation angle θ2 from the first rotation angle θ1. An estimated combustion pressure can be calculated.

  The engine control device 20 calculates an accumulated combustion pressure by accumulating the estimated maximum combustion pressure that may adversely affect the durability of the engine 10. The engine control device 20 starts the abnormal combustion suppression control when the accumulated combustion pressure becomes larger than a predetermined specified value.

  The characteristics of the engine 10 vary depending on the environment in which the engine 10 is used, the accumulated operation time of the engine 10, and the like. For this reason, the engine control device 20 optimizes the value of the estimated maximum combustion pressure used for calculation of the cumulative combustion pressure based on the cumulative combustion pressure optimization process during the operation of the engine 10.

The accumulated combustion pressure calculation optimization process will be described with reference to FIG.
The engine control device 20 repeatedly executes this cumulative combustion pressure optimization process at regular intervals during the operation of the engine 10.

  In step S11, the engine control device 20 determines whether or not abnormal combustion has occurred. The engine control device 20 determines that abnormal combustion has occurred when the detection signal of the knock sensor 11 is greater than a predetermined value. The engine control device 20 repeats step S11 until it is determined in step S11 that abnormal combustion has occurred. The engine control device 20 counts the number of occurrences of abnormal combustion. When it is determined in step S11 that the abnormal combustion has occurred, the engine control device 20 counts up the abnormal combustion cumulative number, which is a value obtained by counting the number of occurrences of the abnormal combustion. When it is determined in step S11 that abnormal combustion has occurred, the engine control device 20 calculates an estimated maximum combustion pressure in step S12.

  In step S13, the engine control device 20 determines whether or not the abnormal combustion accumulation count has reached a predetermined value. In step S13, the engine control device 20 repeats steps S11 to S13 until the cumulative number of abnormal combustion reaches a specified value. When it is determined in step S13 that the cumulative number of abnormal combustion has reached the specified value, the engine control device 20 calculates an estimated maximum combustion pressure distribution (see FIG. 4) in step S14. In step S15, the engine control device 20 learns a new estimated maximum combustion pressure distribution and optimizes the cumulative combustion pressure.

An example of learning for optimizing the cumulative combustion pressure will be described below.
FIG. 4 shows the estimated maximum combustion pressure distribution when abnormal combustion occurs.
The engine control device 20 calculates an estimated maximum combustion pressure histogram corresponding to the cumulative number of abnormal combustions of a predetermined specified value as the estimated maximum combustion pressure distribution. FIG. 4A is an estimated maximum combustion pressure histogram when the accumulated operation time of the engine 10 is extremely short, for example. FIG. 4B is an estimated maximum combustion pressure histogram after elapse of a long cumulative operation time, for example.

  The engine control device 20 defines an estimated maximum combustion pressure region of D to H in which the estimated maximum combustion pressure is larger than a predetermined value as a component damage occurrence region that may adversely affect the durability of the engine.

  The engine control device 20 gives a weighting coefficient to each estimated maximum combustion pressure. The engine control device 20 changes the weighting factor according to the distribution shape of the estimated maximum combustion pressure histogram by performing the cumulative combustion pressure optimization process.

  When the distribution shape of the estimated maximum combustion pressure histogram shown in FIG. 4A is set, for example, the engine control device 20 sets the weight coefficient of each of the plurality of estimated maximum combustion pressures to “1”. The engine control device 20 changes the value of the weighting coefficient according to the amount of deviation from the distribution shape of the estimated maximum combustion pressure histogram from FIG.

  For example, when the estimated maximum combustion pressure histogram shown in FIG. 4B has a distribution shape, the engine control device 20 determines that the occurrence frequency of abnormal combustion in the part damage occurrence region is high. The engine control device 20 sets the weight coefficient of each of the plurality of estimated maximum combustion pressures in the part damage occurrence region to a value less than “1” and greater than “0”.

  Further, the engine control device 20 determines that the occurrence frequency of abnormal combustion that becomes the estimated maximum combustion pressure of E is prominent in the distribution shape shown in FIG. The engine control device 20 sets the weight coefficient of the estimated maximum combustion pressure of E to a smaller value.

  The engine control device 20 calculates the cumulative combustion pressure by multiplying each estimated maximum combustion pressure included in the part damage occurrence region of the estimated maximum combustion pressure histogram by the weighting factor set by the cumulative combustion pressure calculation optimization process. The engine control device 20 determines whether or not the abnormal combustion suppression control is necessary based on the calculated cumulative combustion pressure value.

The engine control device 20 has the following effects.
The engine control device 20 calculates the estimated maximum combustion pressure distribution based on the estimated maximum combustion pressure calculated based on the detection signal of the knock sensor 11. The engine control device 20 sets a weighting factor according to the distribution shape of the estimated maximum combustion pressure distribution, and calculates the cumulative combustion pressure. The engine control device 20 determines whether or not abnormal combustion suppression control is necessary based on the accumulated combustion pressure. For this reason, even if the distribution shape of the estimated maximum combustion pressure distribution changes, the engine control device 20 can learn the changed distribution shape and calculate the cumulative combustion pressure according to the new distribution shape. For this reason, the engine control device 20 can accurately determine whether or not the abnormal combustion suppression control is necessary even when the environment in which the engine 10 is used is different or when the engine characteristics fluctuate without using the in-cylinder pressure sensor. Can be determined.

  DESCRIPTION OF SYMBOLS 10 ... Engine, 11 ... Knock sensor, 20 ... Engine control apparatus.

Claims (1)

An engine control device for an engine equipped with a knock sensor,
The engine control device
Calculate the estimated maximum combustion pressure based on the detection signal of the knock sensor,
Based on the estimated maximum combustion pressure, calculate an estimated maximum combustion pressure distribution,
Based on the estimated maximum combustion pressure distribution, calculate a cumulative combustion pressure of a plurality of the estimated maximum combustion pressure,
An engine control device that determines whether or not abnormal combustion suppression control is necessary based on the cumulative combustion pressure.