JP5594218B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine control apparatus, and more particularly to an apparatus for controlling the ignition timing of an internal combustion engine.

  In general, the basic ignition timing (for example, MBT (Minimum advance for Best Torque)) that is set for specific performance corresponding to various operating conditions is pre-adapted using a product tolerance center product. The ignition timing map is stored in an ECU (Electronic Control Unit). Then, ignition timing control according to the operating conditions is performed according to the ignition timing map.

Further, as disclosed in, for example, Patent Document 1, an internal combustion engine that controls ignition timing based on a heat loss amount (heat loss rate: RQw = 1−Q / Q _fuel ) calculated from an output value of the in-cylinder pressure sensor. A control device is known. The correction of the basic ignition timing is facilitated by using the heat loss amount as a parameter.

JP 2008-025406 A JP 2005-233113 A

  By the way, the heat loss is composed of various losses such as exhaust loss, cooling loss, unburned loss, pump loss and the like. In particular, the exhaust loss and the cooling loss are highly sensitive to the ignition timing. Therefore, when the hard state changes due to secular change, deposit accumulation, etc., and the optimal ignition timing deviates from the basic ignition timing stored in the ignition timing map, the cooling loss and the exhaust loss change with high sensitivity. In the control device for a conventional internal combustion engine, since the exhaust loss and the cooling loss are not distinguished, it is impossible to judge the influence of these changes on the ignition timing. Therefore, it cannot be said that the ignition timing can be properly corrected, and there is a possibility that fuel consumption and drivability deteriorate.

  The present invention has been made to solve the above-described problems, and appropriately corrects the ignition timing in response to changes in the optimal ignition timing due to secular change, deposit accumulation, etc., and deteriorates fuel consumption and drivability. It is an object of the present invention to provide a control device for an internal combustion engine that can suppress the above-described problem.

In order to achieve the above object, a first invention is a control device for an internal combustion engine,
Basic ignition timing determination means for determining basic ignition timing according to the operating conditions of the internal combustion engine;
A loss amount calculating means for calculating a loss amount of at least one of an exhaust loss amount and a cooling loss amount when ignited at the basic ignition timing;
Basic ignition timing correction means for correcting the basic ignition timing based on a change amount of the loss amount with respect to a basic loss value determined according to the basic ignition timing.

The second invention is the first invention, wherein
The loss amount calculating means calculates at least the exhaust loss amount,
The basic loss value includes a basic exhaust loss value determined according to the basic ignition timing,
The basic ignition timing correction means corrects the basic ignition timing to a retard side as the exhaust loss amount becomes smaller than the basic exhaust loss value, and advances the basic ignition timing as the exhaust loss amount becomes larger than the basic exhaust loss value. Correction to the side.

The third invention is the first or second invention, wherein
The loss amount calculating means calculates at least the cooling loss amount,
The basic loss value includes a basic cooling loss value determined according to the basic ignition timing,
The basic ignition timing correction means corrects the basic ignition timing to the retard side as the cooling loss amount becomes larger than the basic cooling loss value, and advances the basic ignition timing as the cooling loss amount becomes smaller than the basic cooling loss value. Correction to the side.

Moreover, 4th invention is set in 1st invention,
The loss amount calculating means calculates the exhaust loss amount and the cooling loss amount,
The basic loss value is a ratio of a basic exhaust loss amount to a basic cooling loss amount determined according to the basic ignition timing,
The basic ignition timing correction means corrects the basic ignition timing to an advance side as the ratio of the exhaust loss amount to the cooling loss amount becomes larger than the basic loss value, and as the smaller the basic loss value becomes, the basic ignition timing correction unit corrects the basic ignition timing. The basic ignition timing is corrected to the retard side.

  According to the first aspect of the invention, the amount of loss when ignition is performed at the basic ignition timing corresponding to the current operating conditions is calculated, and the basic loss value at the basic ignition timing corresponding to the current operating conditions and the amount of change in the loss amount are calculated. The basic ignition timing can be corrected. Therefore, according to the present invention, it is possible to appropriately correct the basic ignition timing in response to changes in the optimal ignition timing due to secular change, deposit accumulation, and the like, and to suppress deterioration in fuel consumption and drivability.

  According to the second invention, the basic ignition timing is corrected to the retard side as the exhaust loss amount becomes smaller than the basic exhaust loss value, and the basic ignition timing is corrected to the advance side as it becomes larger than the basic exhaust loss value. Can do. For this reason, according to the present invention, the basic ignition timing can be corrected so as to approach the optimal ignition timing using exhaust loss with high sensitivity to the ignition timing.

  According to the third invention, the basic ignition timing is corrected to the retard side as the cooling loss amount becomes larger than the basic cooling loss value, and the basic ignition timing is corrected to the advance side as it becomes smaller than the basic cooling loss value. Can do. For this reason, according to the present invention, the basic ignition timing can be corrected so as to approach the optimum ignition timing by using a cooling loss with high sensitivity to the ignition timing.

  According to the fourth aspect of the invention, the basic ignition timing can be corrected so as to approach the optimal ignition timing using the exhaust loss and the cooling loss that are highly sensitive to the ignition timing.

It is a schematic block diagram for demonstrating the system configuration | structure of Embodiment 1 of this invention. It is a figure which shows the relationship between the exhaust loss in a predetermined | prescribed operating condition, and a cooling loss. It is a flowchart of the control routine which ECU50 performs in Embodiment 1 of this invention. It is a figure which shows the relationship between the breakdown of the calorie | heat amount of all the fuel supplied, and the heat generation amount for every crank angle (theta).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
[System Configuration of Embodiment 1]
FIG. 1 is a schematic configuration diagram for explaining a system configuration according to the first embodiment of the present invention. The system shown in FIG. 1 includes an internal combustion engine (hereinafter simply referred to as an engine) 10. The engine 10 is a spark ignition type four-stroke engine.

  Although only one cylinder is depicted in FIG. 1, the vehicle engine 10 is generally composed of a plurality of cylinders. Each cylinder is provided with a piston that reciprocates inside thereof. The space from the piston upper surface of each cylinder to the cylinder head forms a combustion chamber 12. A direct injection valve 14 that directly injects fuel into the combustion chamber 12 is attached to each cylinder. A spark plug 16 is attached to each cylinder. Each cylinder is provided with a cylinder pressure sensor (CPS) 18 for detecting the cylinder pressure (combustion pressure) in the combustion chamber 12. The reciprocating motion of the piston is converted into the rotational motion of the crankshaft. A crank angle sensor 19 for detecting a rotation angle of the crankshaft (hereinafter referred to as a crank angle θ) is attached in the vicinity of the crankshaft.

  An intake passage 20 connected to each cylinder is provided in the intake system of the engine 10. An air cleaner 22 is provided at the inlet of the intake passage 20. An air flow meter 24 for detecting a flow rate of air taken into the intake passage 20 (hereinafter referred to as intake air amount) is attached downstream of the air cleaner 22. An electronically controlled throttle valve 26 is provided downstream of the air flow meter 24. A throttle opening sensor 27 for detecting the opening of the throttle valve 26 (hereinafter referred to as the throttle opening) is attached in the vicinity of the throttle valve 26. A surge tank 28 is provided downstream of the throttle valve 26. An intake pressure sensor 30 for measuring intake pressure is attached in the vicinity of the surge tank 28.

  An exhaust passage 32 connected to each cylinder is provided in the exhaust system of the engine 10. A catalyst 34 is provided in the exhaust passage 32. As the catalyst, for example, a three-way catalyst is used.

  An ECU (Electronic Control Unit) 50 is provided in the control system of the engine 10. In addition to the in-cylinder pressure sensor 18, the crank angle sensor 19, the air flow meter 24, the throttle opening sensor 27, the intake pressure sensor 30, a water temperature sensor for detecting the coolant temperature of the engine 10 is provided at the input portion of the ECU 50. Various sensors for detecting the operation state, such as 52, are connected. Various actuators for controlling the operation state of the direct injection valve 14, the ignition plug 16, the throttle valve 26 and the like described above are connected to the output portion of the ECU 50.

  The ECU 50 controls the operating state (ignition timing, fuel injection amount, throttle opening, etc.) of the engine 10 by operating various actuators according to a predetermined program based on the outputs of the various sensors described above. Further, the ECU 50 can calculate the in-cylinder volume determined by the engine speed and the piston position from the crank angle θ.

  Further, the ECU 50 stores a map (hereinafter referred to as an ignition timing map) that defines an ignition timing (ignition timing for MBT) that realizes optimal combustion according to various operating conditions. The ignition timing map is determined in advance by performing fitting using a product tolerance center product. Ignition timing control according to the operating conditions is performed according to the ignition timing map. In the following description, the ignition timing determined in this ignition timing map is referred to as basic ignition timing.

  However, if the hardware conditions are different from the ones that have been adapted due to aging, deposit accumulation, or large product variations, the ignition timing for achieving optimal combustion (ignition timing for MBT) is the ignition timing. It will deviate from the basic ignition timing set in the map. If optimal combustion is not realized, there is a concern about deterioration of fuel consumption and drivability.

[Characteristic Control in Embodiment 1]
(Outline of characteristic control)
An outline of characteristic control of the present embodiment that solves such problems will be described. There is a relationship expressed by the equation (1) between the amount of heat of all the fuel supplied by the direct injection valve 14 and the illustrated work and main loss.
Calorie of all supplied fuel = work shown + exhaust loss + cooling loss + unburnt loss + pump loss
... (1)

  In equation (1), the ignition timing at which the illustrated work is maximum, that is, the ignition timing at which the sum of various losses is minimum is the most efficient ignition timing (MBT). Among the various losses in equation (1), the variables that are highly sensitive to the ignition timing are the exhaust loss and the cooling loss, and the ignition timing that minimizes the sum of the exhaust loss and the cooling loss is the most efficient ignition. It is considered the time.

  FIG. 2 is a diagram illustrating the relationship between exhaust loss and cooling loss under predetermined operating conditions. Dashed lines 60a, 62a, and 64a represent the cooling loss, exhaust loss, and their sum (hereinafter also simply referred to as initial values) at the time of adaptation. Solid lines 60b, 62b, and 64b represent the cooling loss, the exhaust loss, and the sum thereof, which have changed due to secular change or the like. In FIG. 2, the cooling loss changes from the broken line 60a to the solid line 60b, the exhaust loss changes from the broken line 62a to the solid line 62b, and the sum of the exhaust loss and the cooling loss changes from the broken line 64a to the solid line 64b. In this example, the ignition timing at which MBT is changed and the ignition timing at which MBT is advanced is advanced from the basic ignition timing α defined in the ignition timing map to the ignition timing β.

  As described above, the smaller the cooling loss is (the larger the exhaust loss is), the ignition timing at which MBT tends to be advanced. This is because the longer the ignition timing is retarded from the ignition timing at which MBT is reached, the lower the maximum combustion temperature, and the shorter the heat transfer time, the smaller the cooling loss, and the burned heat is used for work. This is because the exhaust loss increases because it is exhausted. Similarly, as the exhaust loss decreases (the cooling loss increases), the ignition timing at which MBT tends to be changed to the retard side.

  Therefore, in the system of the present embodiment, exhaust loss and cooling loss are calculated when ignition is performed at the basic ignition timing, and when the cooling loss is smaller than the basic cooling loss value, or the exhaust loss is lower than the basic exhaust loss value. If the value is also larger, the basic ignition timing is corrected to the advance side. On the other hand, when the exhaust loss is smaller than the basic exhaust loss value, or when the cooling loss is larger than the basic cooling loss value, the basic ignition timing is corrected to the retard side. The basic cooling loss value and the basic exhaust loss value described above refer to the cooling loss and exhaust loss when the basic ignition timing is an ignition timing at which MBT is achieved (when the hard conditions are the same as those at the time of adaptation).

(Control routine)
FIG. 3 is a flowchart of a control routine executed by the ECU 50 in order to realize the above-described operation. In the starting state of this routine, the ECU 50 acquires the basic ignition timing corresponding to the operating conditions such as the engine speed and the load from the above ignition timing map, and controls the spark plug 16 based on the basic ignition timing. . In the routine shown in FIG. 3, first, in step S100, the exhaust loss and the cooling loss are calculated. A specific method for calculating the exhaust loss and the cooling loss will be described with reference to FIG.

  First, a heat generation amount Q generated in one cycle is calculated. FIG. 4 shows the heat generation amount (solid line 70) for each crank angle θ. The amount of heat generated Q is the cylinder pressure (combustion pressure) P detected by the cylinder pressure sensor 18, the cylinder volume V determined by the piston position for each crank angle θ, the specific heat ratio κ, and the intake valve closing in the compression stroke. The crank angle range from the time until the exhaust valve opening in the exhaust stroke can be calculated based on the equation (2) as an integration interval. The calculation method of the heat generation amount Q is described in, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2008-025406) and the like, and thus detailed description thereof is omitted.

・・・（２）

... (2)

  Next, the heat quantity of all the supplied fuel is calculated. The amount of heat of all supplied fuel can be calculated, for example, from the product of the lower heating value of the fuel and the fuel injection amount.

  Subsequently, exhaust loss and cooling loss are calculated (step S100). As shown in FIGS. 4 and (1), the amount of heat of all the supplied fuel is represented by the sum of pump loss, illustrated work, exhaust loss, cooling loss, and unburned loss. Among these, the pump loss and the illustrated work can be calculated from the area of the bag-like loop drawn on the PV diagram representing the relationship between the in-cylinder pressure (combustion pressure) P and the in-cylinder volume V. Since these calculation methods are known, the description thereof is omitted. Further, the ECU 50 stores a map in which unburned loss is determined according to operating conditions (engine speed, load, intake air temperature, etc.). Unburned loss is obtained from this map according to the operating conditions.

  In step S100, the exhaust loss can be calculated by subtracting the pump loss and the illustrated work from the heat generation amount Q generated in one cycle. The cooling loss can be calculated by subtracting the heat generation amount Q generated in one cycle and the unburned loss from the heat amount of all the supplied fuel.

  Next, in step S110, (exhaust loss / cooling loss) -initial value is calculated and compared with threshold values A and B. This initial value is the ratio between the basic cooling loss and the basic exhaust loss when ignition is performed at the basic ignition timing corresponding to the current operating conditions under the same hardware conditions as when the ignition timing map is adapted. The ECU 50 stores in advance a map that defines initial values (basic exhaust loss / basic cooling loss) for each operating condition and basic ignition timing. The ECU 50 acquires an initial value from the map according to the same operation condition as the current operation condition. The threshold A is a value equal to or higher than the threshold B. For example, the threshold A is a positive value and the threshold B is a negative value. Both may be 0.

  In step S110, when (exhaust loss / cooling loss) -initial value is smaller than threshold A and larger than threshold B, it is determined that the condition is not satisfied, and the processing of this routine is terminated. On the other hand, if (exhaust loss / cooling loss) -initial value is not less than threshold A or not more than threshold B in step S110, it is determined that the condition is satisfied, and the ignition timing map is uniformly corrected in step S120. .

  Specifically, (exhaust loss / cooling loss) —when the initial value is equal to or greater than the threshold value A, the ignition timing map is uniformly corrected to the advance side. The correction to the advance side is set to a larger value as the difference from the threshold A is larger. Further, when the (exhaust loss / cooling loss) -initial value is equal to or less than the threshold value B, the ignition timing map is uniformly corrected to the retard side. The correction to the retard side is set to a larger value as the difference from the threshold B is larger. These corrections are determined by experiments or the like so as not to exceed the ignition timing for MBT.

  As described above, according to the routine shown in FIG. 3, the ignition timing map can be uniformly corrected to the retard side as the exhaust loss decreases or the cooling loss increases. Further, the ignition timing map can be uniformly corrected to the advance side as the exhaust loss increases or the cooling loss decreases. Therefore, it is possible to correct the basic ignition timing and bring it closer to the ignition timing at which MBT has changed due to secular change or the like. According to the system of the present embodiment, it is possible to realize an ignition timing that becomes MBT in the next cycle and thereafter. Therefore, deterioration of fuel consumption and drivability can be suppressed.

  By the way, in the system of the first embodiment described above, the exhaust loss and the cooling loss are calculated and the basic ignition timing is corrected based on these ratios, but the basic ignition timing correction method is limited to this. It is not something. Specifically, the correction may be performed as follows. First, the ECU 50 determines the basic ignition timing according to the current operating conditions from the ignition timing map. Next, at least one of the exhaust loss and the cooling loss when ignited at this basic ignition timing is calculated. Further, the ECU 50 stores a basic exhaust loss value and a basic cooling loss value according to the operating conditions in advance as a map, and acquires a basic exhaust loss value and a basic cooling loss value according to the current operating condition from this map. The basic cooling loss value and the basic exhaust loss value refer to cooling loss and exhaust loss when the basic ignition timing is an ignition timing at which MBT is achieved (when the hard conditions are the same as those at the time of adaptation). The ignition timing map is uniformly corrected to the retard side as the exhaust loss becomes smaller than the basic exhaust loss value or as the cooling loss becomes larger than the basic cooling loss value. On the other hand, the ignition timing map is uniformly corrected to the advance side as the exhaust loss becomes larger than the basic exhaust loss value or as the cooling loss becomes smaller than the basic cooling loss value. According to such a method, the basic ignition timing can be corrected based on one or both of the exhaust loss and the cooling loss, and can be brought close to the ignition timing at which the MBT has changed due to secular change or the like.

Moreover, in the system of Embodiment 1 mentioned above, it is supposed that the heat release rate Q will be calculated based on Formula (2) (step S100), but the calculation method of the heat release rate Q is limited to this. is not. Since the change pattern of the heat generation amount Q with respect to the crank angle and the change of the product value ^PVκ with respect to the crank angle have a correlation, the heat generation amount Q may be calculated based on this. Such a calculation method of the heat generation amount Q is described in, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2008-025406) and the like, and thus description thereof is omitted.

  Further, the engine to which the present invention is applied is not limited to the in-cylinder direct injection engine as in the above-described embodiment. The present invention can also be applied to a port injection type engine.

  In the first embodiment described above, the ECU 50 and the ignition timing map correspond to the “basic ignition timing determining means” in the first invention. In addition, here, the ECU 50 executes the process of step S100, so that the “loss amount calculating means” in the first invention executes the process of steps S110 to S120, so that the first invention is executed. The “basic ignition timing correction means” in FIG.

10 Engine 12 Combustion chamber 14 Direct injection valve 16 Spark plug 18 In-cylinder pressure sensor 19 Crank angle sensor 24 Air flow meter 26 Throttle valve 27 Throttle opening sensor 30 Intake pressure sensor 34 Catalyst 52 Water temperature sensor

Claims (1)

Basic ignition timing determination means for determining basic ignition timing according to the operating conditions of the internal combustion engine;
A loss amount calculating means for calculating a loss amount of at least one of an exhaust loss amount and a cooling loss amount when ignited at the basic ignition timing;
Basic ignition timing correction means for correcting the basic ignition timing based on a change amount of the loss amount with respect to a basic loss value determined according to the basic ignition timing ,
The loss amount calculating means calculates the exhaust loss amount and the cooling loss amount,
The basic loss value is a ratio of a basic exhaust loss amount to a basic cooling loss amount determined according to the basic ignition timing,
The basic ignition timing correction means corrects the basic ignition timing to an advance side as the ratio of the exhaust loss amount to the cooling loss amount becomes larger than the basic loss value, and as the smaller the basic loss value becomes, the basic ignition timing correction unit corrects the basic ignition timing. Correcting the basic ignition timing to the retarded side,
A control device for an internal combustion engine.

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