JP2011214400A - Ignition control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ignition control device for an internal combustion engine improved by balancing avoidance of outbreaks of a knock with lowering of engine output.SOLUTION: This ignition control device for an internal combustion engine includes: a knock control means (S14) which retards the ignition time by a predetermined quantity when outbreaks of a knock in the engine is detected; and an air pressure compensating means (S15) which corrects the predetermined quantity so as to be reduced as the air pressure is lower. With this structure, since the amount of ignition lag by the knock control means is restricted as the air pressure is lower, the sureness of avoidance of a knock by the knock control means is reduced, but remarkable lowering of the engine output can be prevented. In other words, a balance between the sureness of avoidance of a knock due to an ignition lag and the improvement of engine output by restricting the amount of ignition lag can be optimized.

Description

  The present invention relates to an ignition control device for an internal combustion engine provided with knock control means for retarding an ignition timing when a knock occurs in the internal combustion engine.

  There is a knock control in which the ignition timing is retarded by a predetermined amount every time the occurrence of knock in the internal combustion engine is detected, and the ignition timing is advanced by a predetermined amount every time a state where no knock occurrence is detected continues for a predetermined time. Conventionally known (see Patent Document 1). According to this knock control, the ignition timing can be advanced to the limit at which knock does not occur, and the ignition timing can be brought close to the optimum ignition timing (MBT: Minimum advance for the Best Torque) that maximizes the engine output efficiency. .

Japanese Patent No. 2920222

  By the way, when the internal combustion engine is operated at a high altitude with a low atmospheric pressure, the mass flow rate of air sucked into the combustion chamber is reduced. Therefore, if the conditions such as the throttle valve opening and the fuel injection amount are the same, the engine output is lower than that in the low altitude when operating in the high altitude.

  Therefore, when the above-described knock control is performed at a high altitude, if the ignition timing is retarded due to the occurrence of the knock, the engine output decreases due to the high altitude, and further the ignition retard As a result, the engine output decreases, and the engine output decreases significantly.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an ignition control device for an internal combustion engine that improves the balance between avoidance of knocking and reduction in engine output.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  According to the first aspect of the present invention, the knock control means for retarding the ignition timing by a predetermined amount when the occurrence of knock in the internal combustion engine is detected, and the lower the atmospheric pressure at the location where the internal combustion engine is located, the lower the position. And an atmospheric pressure correcting means for correcting so as to reduce the quantification.

  According to this, the lower the atmospheric pressure at the place where the internal combustion engine is located, the smaller the ignition delay amount by the knock control means, so the reliability of knock avoidance by the knock control means is reduced, but the engine output is remarkably high. It can suppress that it falls. In other words, it is possible to optimize the balance between the certainty of knock avoidance due to the ignition retard and the improvement in engine output due to suppression of the ignition retard amount.

  However, knocking is more likely to occur as the temperature of the internal combustion engine increases. Therefore, at such a high temperature, it is desirable to change the balance so as to reduce the effect of improving engine output and improve the reliability of knock avoidance. In view of this point, in the invention according to claim 2, when the temperature of the internal combustion engine is higher than a predetermined upper limit value, the correction by the atmospheric pressure correction means is prohibited regardless of the magnitude of the atmospheric pressure. Features. According to this, at a high temperature at which knocking is likely to occur, the balance is changed to the side where priority is given to avoiding knocking as described above, so that optimization of the balance can be promoted.

  According to a third aspect of the present invention, when the temperature of the internal combustion engine is equal to or lower than the upper limit value, the correction amount by the atmospheric pressure correction means is set to be small as the temperature of the internal combustion engine approaches the upper limit value. Features. According to this, as the temperature of the internal combustion engine approaches the upper limit value, the correction amount by the atmospheric pressure correcting means is set to be small, so that the balance is gradually changed to a side that gives priority to knock avoidance as the temperature becomes higher. Therefore, the balance can be finely optimized.

  On the other hand, knocking is less likely to occur as the temperature of the internal combustion engine becomes lower. Therefore, at such a low temperature, even if the ignition retard amount is suppressed to improve the engine output, the reliability of knock avoidance does not decrease so much. In view of this point, in the invention according to claim 4, when the temperature of the internal combustion engine is lower than a predetermined lower limit value, the predetermined amount is made zero regardless of the magnitude of the atmospheric pressure, and the knock control means The retard is stopped. According to this, at a low temperature at which knocking is difficult to occur, the balance is changed to the side for improving the engine output as described above, so that the optimization of the balance can be promoted.

  According to a fifth aspect of the invention, there is provided temperature correction means for correcting so that the predetermined amount is decreased as the temperature of the internal combustion engine is lower. Since the knock is less likely to occur as the temperature of the internal combustion engine is lower, according to the above invention in which the ignition delay amount is suppressed as the temperature is lower, the optimization of the balance can be promoted.

The figure which shows the whole engine control system to which the ignition control apparatus concerning one Embodiment of this invention is applied. The timing chart which shows the one aspect | mode at the time of performing knock control by ECU of FIG. The flowchart which shows the process sequence of the ignition timing control and knock control by ECU of FIG. The map used for calculation of the correction coefficient C by the process of FIG.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.

  First, a schematic configuration of the entire engine control system will be described with reference to FIG. The engine 11 (internal combustion engine) is mounted on a vehicle and functions as a travel drive source, and is an ignition type gasoline engine. It is also a multi-cylinder engine having a plurality of cylinders. A fuel injection valve 12 for injecting fuel is attached to an intake pipe 13, and a port injection type engine is adopted. An ignition plug 14 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each ignition plug 14.

  The cylinder block of the engine 11 includes a water temperature sensor 15 that detects the temperature of engine cooling water, a knock sensor 16 that detects knock vibration, and a crank that outputs a pulse signal each time the crankshaft of the engine 11 rotates a predetermined crank angle. An angle sensor 17 is attached. Based on the output signal of the crank angle sensor 17, the crank angle and the engine rotation speed are detected. Furthermore, in this embodiment, the atmospheric pressure sensor 18 for detecting the atmospheric pressure is mounted.

  Outputs of these various sensors are input to an engine control device (hereinafter referred to as “ECU 19”). The ECU 19 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), thereby allowing the fuel injection amount of the fuel injection valve 12 and the ignition timing of the spark plug 14 to be executed. To control.

  Regarding the ignition timing by the spark plug 14, the ECU 19 calculates a basic ignition timing based on the engine load and the engine speed. Specifically, the basic ignition timing is advanced as the engine speed increases, and the basic ignition timing is advanced as the engine load increases. Various corrections are performed on the basic ignition timing by warm-up correction and knock control described below to calculate a target ignition timing. Then, the operation of the spark plug 14 is controlled (ignition timing control) so as to be ignited at the target ignition timing.

  The ECU 19 performs warm-up correction that retards the ignition timing by a predetermined amount during the warm-up operation of the engine 11 in which the engine coolant is at a predetermined temperature or lower. This stabilizes the combustion state and promotes an increase in combustion temperature, thereby promoting warm-up operation.

  Further, the ECU 19 calculates the vibration intensity from the output signal of the knock sensor 16 for each ignition, and determines that knock has occurred when the vibration intensity is higher than the knock determination value KC. When it is determined that knocking has occurred, the ignition timing is retarded to suppress the knocking, and when the state without knocking continues, the knocking control is performed to advance the ignition timing. As a result, the ignition timing is advanced within the range of the knocking sound that is permissible for audibility to improve the engine output (engine output) and fuel consumption. According to this knock control, the ignition timing can be advanced to the limit at which knock does not occur, and the target ignition timing can be brought close to the optimum ignition timing MBT.

  FIG. 2 is a timing chart showing one mode when the knock control is executed. (A) shows a change in the knock determination signal output when it is determined that there is a knock, and (b) shows the ignition timing. Shows changes. Thus, each time the knocking determination is made, the ignition timing is retarded by a predetermined amount (see symbol D1 in the drawing), and when the knocking determination continues for a predetermined number of times, the ignition timing is a predetermined amount (see symbol D2 in the drawing). It has been advanced. The retard amount D1 and the advance amount D2 are set to the same amount.

  By the way, when the engine 11 is operated at a high altitude with a low atmospheric pressure, the mass flow rate of the air sucked into the combustion chamber 11a decreases. Therefore, if the conditions such as the throttle valve opening and the fuel injection amount are the same, the engine output is lower than that in the lowland when operating in the highland. Therefore, when the above-described knock control is performed at a high altitude, if the ignition timing is retarded due to the occurrence of the knock, in addition to the engine output decreasing due to the high altitude, the ignition retard is further reduced. As a result, the engine output decreases, so the engine output decreases significantly.

  In the present embodiment in view of this point, atmospheric pressure correction is performed to correct the retard amount D1 by knock control so that the retardation amount D1 decreases as the atmospheric pressure decreases. In addition, the lower the temperature of the engine 11, the lower the combustion temperature, so that knocking is less likely to occur. Therefore, in the present embodiment, temperature correction is performed so that the retard amount D1 is decreased as the engine temperature is lower.

  Next, processing procedures of the ignition timing control and the knock control described above will be described with reference to the flowchart of FIG. This process is repeatedly executed at a predetermined cycle by a microcomputer included in the ECU 19.

  First, in step S10 of FIG. 3, based on the engine load (for example, accelerator operation amount, intake air amount, intake pressure, etc.), the engine rotational speed NE calculated based on the detected value of the crank angle sensor 17, and the detected value of the water temperature sensor 15. The atmospheric pressure calculated based on the calculated coolant temperature and the detected value of the atmospheric pressure sensor 18 is acquired.

  In the subsequent step S11, the basic ignition timing is calculated based on the engine load and engine speed NE acquired in step S10. Specifically, the optimal ignition timing corresponding to the engine load and the engine rotational speed NE is tested in advance, and the basic ignition timing is calculated based on a map created based on the test result.

  In a succeeding step S12, it is determined whether or not the engine is warming up when starting the engine. For example, if the cooling water temperature acquired in step S10 is equal to or lower than a predetermined temperature, it is determined that the warm-up operation is being performed. When the warm-up operation is being performed (S12: YES), in the following step S13, the warm-up delay amount related to the warm-up correction described above is calculated. This warm-up delay amount may be a retarded constant value set in advance, or may be variably set so as to be retarded more as the coolant temperature is lower.

  In the subsequent step S14 (knock control means) and steps S15 and S16 (atmospheric pressure correction means, temperature correction means), the knock retardation amount related to the knock control described above is calculated.

  First, in step S14, the base value Tb of the knock retardation amount is calculated based on the retardation amount D1 and the advance amount D2 described above with reference to FIG. That is, the base value Tb is retarded by a predetermined amount (retard amount D1) every time a knocking determination is made, and the base value Tb is advanced by a predetermined amount (advance amount D2) every time the non-knock determination continues a predetermined number of times. Calculated by letting go.

  In subsequent step S15, a correction coefficient C for the base value Tb is calculated. This correction coefficient C includes the above-described temperature correction and atmospheric pressure correction. That is, as the cooling water temperature acquired in step S10 is lower, the knock retardation amount is decreased (temperature correction), and as the atmospheric pressure acquired in step S10 is lower, the knock retardation amount is decreased (atmospheric pressure correction). In step S16, the correction coefficient C is calculated, and the base value Tb is multiplied by the correction coefficient C (Tb × C) to calculate the knock retardation amount.

  Specifically, an optimum correction coefficient C corresponding to the coolant temperature and atmospheric pressure is tested in advance, and the correction coefficient C is calculated based on a map (see FIG. 4) created based on the test result. The solid line in FIG. 4 is the relationship between the cooling water temperature and the correction coefficient C when the atmospheric pressure is 100 kPa, the broken line in FIG. 4 is the atmospheric pressure is 90 kPa, and the alternate long and short dash line in FIG. Respectively.

  As shown in FIG. 4, the correction coefficient C is set to a smaller value as the cooling water temperature is lower (temperature correction), and is set to a smaller value as the atmospheric pressure is lower (atmospheric pressure correction). Therefore, even if the cooling water temperature is the same (for example, 70 ° C.), if the vehicle is traveling on a high altitude and the atmospheric pressure is lower than normal (100 kPa) (90 kPa, 70 kPa), the pressure is reduced. Only the correction coefficient C is reduced. That is, ΔC1 and ΔC2 in FIG. 4 correspond to the correction amount for the atmospheric correction.

  However, when the cooling water temperature is higher than a predetermined upper limit value T1 (for example, about 80 ° C.), the correction coefficient C is set to 1, so that the base value Tb is set to the knock retardation amount as it is. That is, the atmospheric pressure correction and the temperature correction are prohibited so that the knock retardation amount is set regardless of the magnitude of the atmospheric pressure.

  On the other hand, when the cooling water temperature is lower than a predetermined lower limit value T2 (for example, about 50 ° C.), the knock retardation amount is set to zero by setting the correction coefficient C to zero. That is, the knock control is stopped regardless of whether or not the knock has occurred. Incidentally, the lower limit value T2 is set to a temperature higher than a predetermined temperature used for the warm-up operation determination in step S12.

  In short, the temperature correction and the atmospheric correction are performed on the condition that the cooling water temperature is in the temperature range of the upper limit value T1 or lower and the lower limit value T2 or higher. The above-described atmospheric pressure correction amounts ΔC1, ΔC2 are higher than a predetermined value in the temperature region (70 ° C. in the example of FIG. 4), and the atmospheric pressure correction amounts ΔC1, ΔC1, as the coolant temperature approaches the upper limit value T1. Set ΔC2 small. On the lower temperature side than the predetermined value (70 ° C.), the atmospheric pressure correction amounts ΔC1 and ΔC2 are set to be smaller as the coolant temperature approaches the lower limit value T2. Regardless of the magnitude of the atmospheric pressure, the upper limit value T1 and the lower limit value T2 are set to the same value.

  In the subsequent step S17, the target ignition timing is calculated by correcting the basic ignition timing calculated in step S11 based on the warm-up delay amount calculated in step S13 and the knock delay amount calculated in step S16.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) Since the retard amount D1 by the knock control is decreased as the atmospheric pressure is lower, it is possible to avoid the engine output from rapidly decreasing with one retard amount D1 during high altitude traveling. In other words, although the reliability of knock avoidance by knock control is reduced, it is possible to suppress a significant decrease in engine output, so the reliability of knock avoidance due to ignition retard and the engine output due to suppression of the ignition delay amount associated with high altitude travel. The balance with improvement can be optimized.

  (2) Focusing on the fact that knocking is less likely to occur as the cooling water temperature is lower, and the retard amount D1 required for knock control is reduced as the cooling water temperature is lower. Therefore, the knock retardation amount is excessively increased at low temperatures. Can be avoided.

  (3) When the cooling water temperature is higher than the upper limit value T1, it is regarded as a high temperature state in which knocking is likely to occur, and atmospheric pressure correction is prohibited, so that knock avoidance is prioritized (the correction coefficient C is increased). Side) to change the balance. Therefore, optimization of the balance can be promoted.

  (3) By setting the atmospheric pressure correction amounts ΔC1 and ΔC2 to be smaller as the cooling water temperature approaches the upper limit value T1, on the condition that the cooling water temperature is in the temperature range of the upper limit value T1 or lower and the lower limit value T2 or higher, As the temperature rises, the balance is gradually changed to the side that gives priority to knock avoidance (the side that increases the correction coefficient C). Therefore, the balance can be finely optimized.

  (4) When the cooling water temperature is lower than the lower limit value T2, the engine output is improved by setting the knock retardation amount to zero (disabling the knock control) on the assumption that it is in a low temperature state where knocking hardly occurs. The balance is changed to the side to be corrected (the side to reduce the correction coefficient C). Therefore, optimization of the balance can be promoted.

(Other embodiments)
The present invention is not limited to the description of the above embodiment, and may be modified as follows. Moreover, you may make it combine the characteristic structure of each embodiment arbitrarily, respectively.

  In calculating the basic ignition timing in step S11 in FIG. 3, the basic ignition timing may be calculated based on the atmospheric pressure in addition to the engine load and the engine speed NE. For example, the ignition timing is advanced as the atmospheric pressure is lower. That is, apart from the atmospheric pressure correction related to the knock control in step S16, the atmospheric pressure correction is also performed for the basic ignition timing.

  In the map shown in FIG. 4, the upper limit value T1 and the lower limit value T2 are set to the same value regardless of the magnitude of the atmospheric pressure, but the upper limit value T1 and the lower limit value T2 are set to different values according to the atmospheric pressure. It may be set. In this case, it is desirable to increase the upper limit value T1 and the lower limit value T2 as the atmospheric pressure is lower.

  In the map shown in FIG. 4, the atmospheric pressure correction amounts ΔC1 and ΔC2 are set to be smaller as the cooling water temperature approaches the upper limit value T1 and the lower limit value T2, but the atmospheric pressure correction amounts ΔC1 and ΔC2 are set regardless of the cooling water temperature. May be fixed to a constant value. In the map shown in FIG. 4, the upper limit value T1 and the lower limit value T2 are set to the same value regardless of the atmospheric pressure. However, the upper limit value T1 and the lower limit value T2 can be changed to higher values as the atmospheric pressure decreases. It may be set.

  D1 ... predetermined amount, S14 ... knock control means, S15, S16 ... atmospheric pressure correction means, temperature correction means, T1 ... predetermined upper limit value, T2 ... predetermined lower limit value.

Claims (5)

A knock control means for retarding the ignition timing by a predetermined amount when knocking of the internal combustion engine is detected;
Atmospheric pressure correction means for correcting so that the predetermined amount decreases as the atmospheric pressure at the location where the internal combustion engine is located is lower;
An ignition control device for an internal combustion engine, comprising:   2. The ignition of the internal combustion engine according to claim 1, wherein when the temperature of the internal combustion engine is higher than a predetermined upper limit value, correction by the atmospheric pressure correction unit is prohibited regardless of the magnitude of the atmospheric pressure. Control device.   3. The correction amount by the atmospheric pressure correction means is set to be small as the temperature of the internal combustion engine approaches the upper limit value when the temperature of the internal combustion engine is equal to or lower than the upper limit value. An ignition control device for an internal combustion engine.   2. The retard by the knock control means is stopped when the temperature of the internal combustion engine is lower than a predetermined lower limit value, regardless of the magnitude of the atmospheric pressure, and the predetermined amount is set to zero. The ignition control device for an internal combustion engine according to any one of?   The ignition control device for an internal combustion engine according to any one of claims 1 to 4, further comprising a temperature correction unit that corrects the predetermined amount to decrease as the temperature of the internal combustion engine decreases.

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