JP6743654B2 - Fuel injection amount determination method and fuel injection amount determination device - Google Patents

Description

The present invention relates to a fuel injection amount determination method and a fuel injection amount determination device that determine the fuel injection amount of each cylinder in a two-cylinder engine.

The following Patent Document 1 describes a fuel injection control device that controls the fuel injection amount of each cylinder of a two-cylinder engine. An intake manifold is connected to each of the two cylinders of the two-cylinder engine described in Patent Document 1. Further, fuel injection valves are attached downstream of these intake manifolds. Further, these intake manifolds are connected by a communication pipe, and an intake pressure sensor for detecting the intake pressure in the communication pipe is provided in the middle of the communication pipe.

Further, an engine control circuit is provided in this two-cylinder engine. The engine control circuit calculates the fuel injection amount of the first cylinder using the bottom pressure of the intake pressure in the communication pipe that decreases due to the intake stroke on the second cylinder side, and reduces the fuel injection amount in the communication pipe on the first cylinder side to reduce the fuel injection amount in the communication pipe. The fuel injection amount of the second cylinder is calculated using the bottom pressure of the intake pressure of.

Japanese Patent Laid-Open No. 10-280995

In the fuel injection control device described in Patent Document 1, the fuel injection amount of each cylinder is calculated using the bottom pressure of the intake pressure in the communication pipe, which decreases due to the intake stroke of the cylinder on the opposite side. However, the change amount of any bottom pressure with respect to the throttle operation is small. Therefore, it is difficult to calculate the fuel injection amount of each cylinder according to the throttle operation with high accuracy.

Further, for example, due to an assembly error of the throttle valve or the throttle body, dust accumulation in the throttle body, or the like, the balance of the intake air amount between the two cylinders is disturbed, and the characteristic of the intake pressure in the communication pipe is a normal characteristic (or ideal Characteristic (hereinafter referred to as "tuning deviation") may occur. When the misalignment occurs, the bottom pressure may change under the influence of the misalignment, and as a result, there is a problem that the calculation accuracy of the fuel injection amount decreases.

The present invention has been made in view of, for example, the problems described above, and an object of the present invention is to increase the fuel injection amount of each cylinder by using the intake pressure in the communication passage that communicates between the intake passages of two cylinders. An object of the present invention is to provide a fuel injection amount determination method and a fuel injection amount determination device that can be determined with accuracy.

In order to solve the above-mentioned problems, a fuel injection amount determination method of the present invention is an engine having a first cylinder and a second cylinder having a phase difference in operation cycle, the first cylinder and the second cylinder. A first intake passage and a second intake passage for supplying air to the first cylinder, a first fuel injection device for supplying fuel to the first cylinder, and a second fuel injection device for supplying fuel to the second cylinder, respectively. Used for an engine system including a communication passage that connects the first intake passage and the second intake passage, and an intake pressure sensor that detects a communication passage intake pressure that is an intake pressure in the communication passage. A method for determining a fuel injection amount of the first fuel injection device and a fuel injection amount of the second fuel injection device based on the communication passage intake pressure and the engine speed, A crank angle range in which both the intake valve of the first cylinder and the intake valve of the second cylinder are closed within the operation cycle period is specified as a detection value acquisition range, and within the one operation cycle period, The crank angle range in which the intake valve of the first cylinder or the intake valve of the second cylinder is opened is specified as the reference value acquisition range, and when the characteristic of the communication passage intake pressure is normal, the communication passage intake pressure is determined. The crank angle within the detection value acquisition range and the crank angle within the reference value acquisition range that are the same as each other are previously specified as the detection value acquisition angle and the reference value acquisition angle, respectively, and the detection is performed within the one operation cycle period. The communication passage intake pressure of the value acquisition angle is acquired as an intake pressure detection value, the communication passage intake pressure of the reference value acquisition angle is acquired as an intake pressure reference value, and the intake pressure detection value and the engine speed are set to The fuel injection amount of the first fuel injection device is determined based on the above, and the intake pressure calculation value calculated using the difference between the intake pressure detection value and the intake pressure reference value, and the engine speed based on the engine speed. The fuel injection amount of the second fuel injection device is determined.

Further, in order to solve the above-mentioned problems, the fuel injection amount determination device of the present invention is an engine having a first cylinder and a second cylinder having a phase difference in operation cycle, the first cylinder and the second cylinder. First intake passage and second intake passage for supplying air to the respective cylinders, and a first fuel injection device and second fuel injection for supplying fuel to the first cylinder and the second cylinder, respectively. An engine system including a device, a communication passage that communicates the first intake passage and the second intake passage, and an intake pressure sensor that detects a communication passage intake pressure that is an intake pressure in the communication passage. A fuel injection amount determination device which is used to determine the fuel injection amount of the first fuel injection device and the fuel injection amount of the second fuel injection device based on the communication passage intake pressure and the engine speed, respectively. , A storage unit and a calculation processing unit, and a crank angle range in which both the intake valve of the first cylinder and the intake valve of the second cylinder are closed within one operation cycle period is referred to as a detection value acquisition range, When the crank angle range in which the intake valve of the first cylinder or the intake valve of the second cylinder is opened within the one operation cycle period is referred to as a reference value acquisition range, the characteristic of the communication passage intake pressure is normal. In the state, the crank angle in the detection value acquisition range and the crank angle in the reference value acquisition range in which the communication passage intake pressure is the same are stored in the storage unit as a detection value acquisition angle and a reference value acquisition angle, respectively. The arithmetic processing unit acquires the communication passage intake pressure of the detection value acquisition angle stored in the storage unit as an intake pressure detection value within the one operation cycle period, and acquires the reference value stored in the storage unit. The intake air pressure at the corner is acquired as an intake pressure reference value, the fuel injection amount of the first fuel injection device is determined based on the intake pressure detection value and the engine speed, and the intake pressure detection value is determined. And the intake pressure reference value, the fuel injection amount of the second fuel injection device is determined based on the intake pressure calculated value and the engine speed.

According to the present invention, the fuel injection amount of each cylinder can be determined with high accuracy by using the intake pressure in the communication passage that communicates between the intake passages of the two cylinders.

It is explanatory drawing which shows the engine system using the fuel injection amount determination method of the Example of this invention. It is explanatory drawing which shows each intake passage in the engine system in FIG. 1, and its peripheral part. FIG. 2 is an explanatory diagram showing an operation cycle of each cylinder, a relationship between a crank angle and an intake pressure of each cylinder, and a relationship between a crank angle and a communication passage intake pressure in the engine system in FIG. 1. 6 is a flowchart showing steps performed before actual use of the engine system in the fuel injection amount determination method according to the embodiment of the present invention. 6 is a flowchart showing steps performed when the engine system is actually used in the fuel injection amount determination method according to the embodiment of the present invention. 3 is a graph showing a relationship between a crank angle and a communication passage intake pressure in the engine system in FIG. 1. When the balance of the intake air amount between the two cylinders is broken in the direction in which the intake air amount of the first cylinder becomes larger than the intake air amount of the second cylinder due to the misalignment, the crank angle and the communication passage intake pressure are It is a graph which shows a relationship etc. When the balance of the intake air amount between the two cylinders is broken in the direction in which the intake air amount of the second cylinder becomes larger than the intake air amount of the first cylinder due to the misalignment, the crank angle and the communication passage intake pressure are It is a graph which shows a relationship etc.

A fuel injection amount determination method according to an embodiment of the present invention includes an engine having a first cylinder and a second cylinder that have a phase difference in operation cycle, and a first cylinder and a second cylinder that supply air to the second cylinder. A first intake passage and a second intake passage, a first fuel injection device and a second fuel injection device for supplying fuel to the first cylinder and the second cylinder, respectively, a first intake passage and a second intake passage Used for an engine system including a communication passage that communicates with the intake passage of the vehicle and an intake pressure sensor that detects the communication passage intake pressure, which is the intake pressure in the communication passage, and is based on the communication passage intake pressure and the engine speed. This is a method of determining the fuel injection amount of the first fuel injection device and the fuel injection amount of the second fuel injection device, respectively.

In the fuel injection amount determination method according to the embodiment of the present invention, the following steps are performed before the engine system is actually used, for example, when the engine system is tested, simulated, or maintained.

That is, the crank angle range in which both the intake valve of the first cylinder and the intake valve of the second cylinder are closed within one operation cycle period is specified as the detection value acquisition range. In such a crank angle range, the amount of change in the communication passage intake pressure with respect to the throttle operation (change in throttle opening) is larger than in other crank angle ranges. Note that this fuel injection amount determination method is assumed to be used in a four-stroke engine, and one operation cycle period corresponds to a period in which the crankshaft of the engine makes two revolutions.

Further, within one operation cycle period, the crank angle range in which the intake valve of the first cylinder or the intake valve of the second cylinder is open is specified as the reference value acquisition range. In such a crank angle range, the characteristic of the communication passage intake pressure changes from the normal characteristic (or the ideal characteristic) due to the imbalance of the intake air amount between the first cylinder and the second cylinder. When the misalignment occurs, the amount of change in the characteristic of the communication passage intake pressure due to the misalignment becomes smaller than in other crank angle ranges. The characteristic of the communication passage intake pressure means the relationship between the crank angle and the communication passage intake pressure in one operation cycle period.

Further, when there is no synchronization deviation and the characteristic of the communication passage intake pressure is in a normal state, the crank angle and the crank angle within the detection value acquisition range where the communication passage intake pressure is the same within one operation cycle period The crank angle within the reference value acquisition range is specified as the detected value acquisition angle and the reference value acquisition angle, respectively.

Further, in the fuel injection amount determination method according to the embodiment of the present invention, the following steps are performed when the engine system is actually used.

That is, within one operation cycle period, the communication passage intake pressure at the detection value acquisition angle is acquired as the intake pressure detection value, and the communication passage intake pressure at the reference value acquisition angle is acquired as the intake pressure reference value.

Then, the fuel injection amount of the first cylinder (first fuel injection device) is determined based on the intake pressure detection value and the engine speed. Further, the intake pressure calculated value is calculated using the difference between the intake pressure detected value and the intake pressure reference value, and the fuel of the second cylinder (second fuel injection device) is calculated based on the intake pressure calculated value and the engine speed. Determine the injection amount.

When the engine system is actually used, a misalignment may occur due to, for example, an assembly error of the throttle valve or the throttle body or dust accumulation in the throttle body.

If the intake air amount of the first cylinder becomes unbalanced in the direction in which the intake air amount of the first cylinder becomes larger than the intake air amount of the second cylinder, the communication passage intake is lost. The characteristic of the atmospheric pressure changes from the normal characteristic, and the communication passage intake pressure of the detection value acquisition angle, that is, the intake pressure detection value increases as compared with the normal state. The degree of increase in the detected intake pressure value increases as the degree of imbalance in the intake air amount between the two cylinders increases. On the other hand, when the balance of the intake air amount between the two cylinders is disturbed in the direction in which the intake air amount of the second cylinder becomes larger than the intake air amount of the first cylinder due to the misalignment, the communication passage intake pressure The characteristic changes from the normal characteristic. In this case, the detected intake pressure value decreases as compared to the normal state. The degree of decrease in the intake pressure detection value increases as the degree of imbalance in the intake air amount between both cylinders increases. However, even if the characteristic of the communication passage intake pressure changes due to such misalignment, the communication passage intake pressure at the reference value acquisition angle, that is, the intake pressure reference value hardly changes. Therefore, the difference between the detected intake pressure value and the reference value of the intake pressure depends on the degree to which the balance of the intake air amount between both cylinders is disturbed (the degree of synchronization deviation) and the balance of the intake air amount between both cylinders. Whether the intake air amount of the cylinder is larger than the intake air amount of the second cylinder, or the intake air amount of the second cylinder is larger than the intake air amount of the first cylinder. It is a value indicating (direction of misalignment).

If the balance of the intake air amount between the two cylinders is disturbed in the direction in which the intake air amount of the first cylinder becomes larger than the intake air amount of the second cylinder due to the misalignment, the intake pressure detection value is The absolute value of the difference between the intake pressure detection value and the intake pressure reference value is larger than the intake pressure detection value when there is no deviation (that is, the intake pressure reference value). Further, in this case, for example, the intake pressure calculated value calculated by using the following mathematical expression (1) is the intake pressure detection value and the intake pressure reference value more than the intake pressure calculated value when the synchronization deviation does not occur. The absolute value of the difference becomes a small value.
Intake pressure detection value-(Intake pressure detection value-Intake pressure reference value) x 2 (1)
Therefore, by determining the fuel injection amount of the first cylinder based on the intake pressure detection value and the engine speed, the direction in which the fuel injection amount of the first cylinder increases as compared to when the misalignment does not occur Adjusted to. Further, by determining the fuel injection amount of the second cylinder based on the calculated intake pressure value and the engine speed, the fuel injection amount of the second cylinder decreases in comparison with the case where there is no misalignment. Adjusted to. Then, each adjustment amount is determined according to the absolute value of the difference between the intake pressure detection value and the intake pressure reference value.

On the other hand, when the balance of the intake air amount between the two cylinders is disrupted in the direction in which the intake air amount of the second cylinder becomes smaller than the intake air amount of the second cylinder due to the misalignment, the detected intake pressure value The absolute value of the difference between the intake pressure detection value and the intake pressure reference value is smaller than the intake pressure detection value (that is, the intake pressure reference value) when there is no misalignment. Further, in this case, for example, the intake pressure calculated value calculated by the above mathematical expression (1) is an absolute value of the difference between the intake pressure detected value and the intake pressure reference value, rather than the intake pressure calculated value when there is no synchronization deviation. The value becomes larger. Therefore, by determining the fuel injection amount of the first cylinder based on the detected intake pressure value and the engine speed, the direction in which the fuel injection amount of the first cylinder decreases as compared to when the misalignment has not occurred Adjusted to. Further, by determining the fuel injection amount of the second cylinder based on the intake pressure calculated value and the engine speed, the direction in which the fuel injection amount of the second cylinder increases as compared with the case where there is no misalignment Adjusted to. Then, each adjustment amount is determined according to the absolute value of the difference between the intake pressure detection value and the intake pressure reference value.

As described above, according to the fuel injection amount determination method of the embodiment of the present invention, the fuel injection amount of the first cylinder and the fuel injection amount of the second cylinder are respectively adjusted according to the degree and direction of the misalignment. You can Therefore, the fuel injection amount of each cylinder can be determined with high accuracy.

Further, the fuel injection amount determination device of the embodiment of the present invention determines the fuel injection amount of each cylinder by the above-described fuel injection determination method of the embodiment of the present invention. That is, the fuel injection amount determination device includes a storage unit and a calculation processing unit, and the detection value acquisition angle and the reference value acquisition angle are stored in the storage unit. The arithmetic processing unit acquires the intake pressure detection value and the intake pressure reference value by using the detection value acquisition angle and the reference value acquisition angle stored in the storage unit, and further calculates the intake pressure calculated value and The fuel injection amount of is determined. According to such a fuel injection amount determination device, the fuel injection amount of each cylinder can be determined with high accuracy.

(Engine system)
FIG. 1 shows an engine system 1 in which a fuel injection amount determination method according to an embodiment of the present invention is used. In the engine system 1 shown in FIG. 1, the engine 11 is a two-cylinder engine having a cylinder C1 as a first cylinder and a cylinder C2 (see FIG. 2) as a second cylinder. Intake passages 13 and 14 (see FIG. 2) are connected to the intake ports 12 of the cylinders C1 and C2, respectively. Each intake passage 13, 14 is specifically an intake pipe. The upstream side of each intake passage 13, 14 is connected to a single air box 15. An air filter 16 is provided inside the air box 15. The combustion air that has flowed into the air box 15 is cleaned by the air filter 16, is then distributed from the air box 15 to the intake passages 13 and 14, and is sucked into the intake ports 12 of the cylinders C1 and C2. It Further, the air box 15 is provided with an intake air temperature sensor 17 that detects the temperature of the intake air. Further, throttle valves 18, 19 (see FIG. 2) are provided in the middle of the intake passages 13, 14 and a throttle opening sensor 20 for detecting the opening of the throttle valves 18, 19 is provided near the throttle valves 18, 19. Is provided.

Further, in the intake passages 13 and 14, fuel injection valves 21 and 22 (see FIG. 2) as fuel injection devices are provided on the downstream side of the throttle valves 18 and 19, respectively. The fuel stored in the fuel tank 25 is pumped up by the fuel pump 26 and sequentially supplied through the fuel pipe 27, the fuel filter 28, the fuel pipe 29 and the delivery pipe 30 to the fuel injection valves 21 and 22. Further, a pressure regulator 31 that adjusts the fuel pressure in relation to the intake pressure in the vicinity of each fuel injection valve 21, 22 and fuel that returns fuel from the delivery pipe 30 to the fuel tank 25 according to the operation of the pressure regulator 31 A pipe 32 is provided.

An ignition plug 33 is provided on the cylinder head of each cylinder C1 and C2, and an ignition coil 34 for igniting the ignition plug 33 is connected to each ignition plug 33. An intake valve 44 is provided in the cylinder head of each cylinder C1, C2. Further, the engine 11 is provided with an engine speed sensor 35 that outputs a pulse signal for each predetermined crank angle in order to detect the engine speed. Further, the engine 11 is provided with a cylinder discrimination sensor 36 for discriminating the cylinder and a water temperature sensor 37 for detecting the temperature of the cooling water. Further, an atmospheric pressure sensor 38 for detecting the atmospheric pressure is provided at a position facing the atmosphere away from the engine 11, for example. Further, the engine system 1 is provided with a gear position sensor 39 that detects the gear position of a transmission provided in a power transmission mechanism that transmits the power of the engine 11 to wheels and the like.

FIG. 2 shows the intake passages 13 and 14 and their peripheral portions. As shown in FIG. 2, a communication passage 41 is provided between the intake passages 13 and 14, and the intake passages 13 and 14 communicate with each other via the communication passage 41. The communication passage 41 connects the portion of the intake passage 13 between the throttle valve 18 and the fuel injection valve 21 and the portion of the intake passage 14 between the throttle valve 19 and the fuel injection valve 22. The communication passage 41 is a narrow passage as compared with the intake passages 13 and 14. The intake air flowing through the intake passages 13 and 14 can pass through the communication passage 41. An intake pressure sensor 42 that detects an intake pressure in the communication passage 41 (hereinafter, referred to as “communication passage intake pressure”) is provided in the middle of the communication passage 41.

Further, as shown in FIG. 1, the engine system 1 is provided with an ECU (engine control unit) 45 that controls the engine 11. The ECU 45 includes a CPU (central processing unit) and can perform various processes related to engine control. The ECU 45 executes the fuel injection amount determination method according to the embodiment of the present invention. The ECU 45 is a specific example of the arithmetic processing unit of the fuel injection amount determination device. Further, an intake air temperature sensor 17, a throttle opening sensor 20, an engine speed sensor 35, a cylinder discrimination sensor 36, a water temperature sensor 37, an atmospheric pressure sensor 38, a gear position sensor 39 and an intake pressure sensor 42 are connected to the ECU 45. There is. The detection signals output from these sensors are input to the ECU 45. Further, the fuel pump 26, the fuel injection valves 21, 22 and the ignition coil 34 are connected to the ECU 45. The ECU 45 outputs control signals to these devices and controls these devices.

Further, the ECU 45 is provided with a storage unit 46 having, for example, a semiconductor storage element. The storage unit 46 stores maps M1, M2 and the like. The map M1 is data for calculating the fuel injection amount of the cylinder C1, and is the difference between the communication passage intake pressure (intake pressure detection value P1) and the atmospheric pressure, the engine speed, and the fuel injection of the fuel injection valve 21. It is data showing the relationship with time. The map M2 is data for calculating the fuel injection amount of the cylinder C2, and the difference between the communication passage intake pressure (intake pressure calculation value P2) and the atmospheric pressure, the engine speed, and the fuel injection of the fuel injection valve 22. It is data showing the relationship with time.

FIG. 3 shows the operation cycle of the cylinders C1 and C2, the characteristic of the intake pressure of the cylinder C1, the characteristic of the intake pressure of the cylinder C2, and the characteristic of the communication passage intake pressure. The engine 11 is a four-stroke engine, and each cylinder C1 and C2 performs a series of operations of intake stroke→compression stroke→combustion/expansion stroke→exhaust stroke while the crankshaft rotates 720 degrees. repeat. The operation cycle means a cycle in which this series of operations is repeated. Further, the phases of the operation cycles are different between the cylinders C1 and C2. In the present embodiment, as shown in FIG. 3, the operation cycle of the cylinder C2 is delayed by 270 degrees with respect to the operation cycle of the cylinder C1.

Further, the characteristic of the intake pressure of the cylinder C1 means the relationship between the crank angle and the intake pressure of the cylinder C1, and the characteristic of the intake pressure of the cylinder C2 means the relationship between the crank angle and the intake pressure of the cylinder C2. To do. Further, the characteristic of the communication passage intake pressure means the relationship between the crank angle and the communication passage intake pressure. Crank angles are different between the operation cycles of the cylinders C1 and C2 shown in the upper side of FIG. 3 and the intake pressure characteristics of the cylinder C1, the intake pressure characteristics of the cylinder C2, and the communication passage intake pressure characteristics shown in the lower side of FIG. 3, respectively. It corresponds. As can be seen from FIG. 3, the communication passage intake pressure is generally a value obtained by averaging the intake pressure of the cylinder C1 and the intake pressure of the cylinder C2.

(Fuel injection amount determination method)
The fuel injection amount determination method according to the embodiment of the present invention is used in the engine system 1 as described above. Hereinafter, the fuel injection amount determination method will be described with reference to FIGS. 4 to 8. The fuel injection amount determination method is a method of determining the fuel injection amount of the cylinder C1 (fuel injection valve 21) and the fuel injection amount of the cylinder C2 (fuel injection valve 22) based on the communication passage intake pressure and the engine speed. .. The steps of the method for determining the fuel injection amount according to the embodiment of the present invention include the steps performed before the actual use of the engine system 1 and the steps performed during the actual use of the engine system 1.

First, the steps performed before the actual use of the engine system 1 will be described. FIG. 4 shows steps performed before the actual use of the engine system 1 in the fuel injection amount determination method according to the embodiment of the present invention. FIG. 6 shows the characteristic of the communication passage intake pressure in the engine system 1.

Before the actual use of the engine system 1, it is assumed that the engine system 1 is tested, simulated, or maintained, for example. Further, in the fuel injection amount determination method according to the embodiment of the present invention, the steps performed before the actual use of the engine system 1 are executed by, for example, a designer, a manufacturer, a maintenance worker or the like of the engine system 1.

First, the engine system 1 in a state where no synchronization deviation occurs (state in which communication passage intake pressure is normal) is prepared. For example, the engine system 1 in which there is no assembly error in the throttle valve 18 or the throttle body and dust or the like is not accumulated in the intake passage 13, the communication passage 41 or the throttle body does not cause misalignment. Such an engine system 1 is prepared.

Next, such an engine system 1 is operated, and as shown in FIG. 4, the gear of the engine system 1 is set to neutral, the throttle opening is set to the reference opening or less, and the engine speed is set to the reference rotation. It is set to be equal to or less than the number (step S1). By setting in this way, the engine 11 is brought into a state in which the intake pressures of the cylinders C1 and C2 are stable, for example, in the idling state in which the engine 11 is sufficiently warmed up. The reference opening degree and the reference rotation speed are set to values at which the engine is in such a state.

Next, within one operation cycle period of the engine, the crank angle range in which both the intake valve 44 of the cylinder C1 and the intake valve 44 of the cylinder C2 are closed is specified as the detection value acquisition range R1 (step S2). In this crank angle range, the amount of change in the communication passage intake pressure with respect to the throttle operation (change in throttle opening) is larger than in other crank angle ranges. In the crank angle range in which both the intake valve 44 of the cylinder C1 and the intake valve 44 of the cylinder C2 are closed, the change amount of the communication passage intake pressure with respect to the throttle operation is significantly increased as compared with the other crank angle ranges. It is preferable to specify such a range as the detection value acquisition range R1. In the present embodiment, as shown in FIG. 6, the crank angle range from approximately 380 degrees to approximately 600 degrees is specified as the detection value acquisition range R1. Note that one operation cycle period corresponds to a period in which the crankshaft of the engine 11 makes two revolutions.

Next, within one operation cycle period, the crank angle range in which the intake valve 44 of the cylinder C1 or the intake valve 44 of the cylinder C2 is closed is specified as the reference value acquisition range R2 (step S3). In this crank angle range, the amount of change in the characteristic of the communication passage intake pressure due to misalignment is smaller than in other crank angle ranges. In the crank angle range in which the intake valve 44 of the cylinder C1 or the intake valve 44 of the cylinder C2 is closed, it is remarkable that the amount of change in the characteristic of the communication passage intake pressure due to the misalignment becomes smaller than that in other crank angle ranges. It is preferable to specify such a range as the reference value acquisition range R2. Here, in FIG. 6, the solid characteristic line shows the characteristic of the communication passage intake pressure in the state where no synchronization deviation occurs, that is, the normal characteristic (or ideal characteristic) of the communication passage intake pressure. Further, the dashed characteristic line indicates a communication passage in the case where the balance of the intake air amount between the cylinders C1 and C2 is disturbed in the direction in which the intake air amount of the cylinder C1 becomes larger than the intake air amount of the cylinder C2 due to misalignment. The characteristic of the intake pressure is shown. Hereinafter, this characteristic may be referred to as “first deformation characteristic”. Further, the dotted characteristic line indicates a communication path in the case where the balance of the intake air amount between the cylinders C1 and C2 is disrupted in the direction in which the intake air amount of the cylinder C2 becomes larger than the intake air amount of the cylinder C1 due to the misalignment. The characteristic of the intake pressure is shown. Hereinafter, this characteristic may be referred to as a "second deformation characteristic". As can be seen from FIG. 6, in the present embodiment, the three characteristic lines, that is, the solid line, the broken line, and the dotted line, approximately overlap in the crank angle range of approximately 240 degrees to 290 degrees. That is, in this crank angle range, the amount of change in the characteristic of the communication passage intake pressure due to the misalignment is extremely small compared to other crank angle ranges. Therefore, in the present embodiment, this crank angle range is specified as the reference value acquisition range R2. The execution order of steps S2 and S3 may be reversed.

Next, within one operation cycle period, the crank angle within the detection value acquisition range R1 and the crank angle within the reference value acquisition range R2 at which the communication passage intake pressures are the same are detected value acquisition angle A1 and reference value acquisition angle A2. Respectively (step S4). The detection value acquisition angle A1 and the reference value acquisition angle A2 can be specified as follows, for example. That is, according to the solid characteristic line (the characteristic line showing the normal characteristic of the communication passage intake pressure) in FIG. 6, the maximum communication passage intake pressure is Q1 and the minimum communication passage intake pressure is in the reference value acquisition range R2. The atmospheric pressure is Q2. Then, in the detected value acquisition range R1, the crank angle range in which the communication passage intake pressure changes from Q2 to Q1 is R3. Therefore, first, any one crank angle within the crank angle range R3 is specified as the detection value acquisition angle A1. Next, within the reference value acquisition range R2, the crank angle at which the communication passage intake pressure Pb is the same as the communication passage intake pressure of the detection value acquisition angle A1 is specified as the reference value acquisition angle A2. The specified detection value acquisition angle A1 and the reference value acquisition angle A2 are stored in the storage unit 46 of the engine system 1.

Next, steps performed when the engine system 1 is actually used will be described. FIG. 5 shows steps performed when the engine system 1 is actually used in the fuel injection amount determination method according to the embodiment of the present invention. FIG. 7 is a characteristic of the communication passage intake pressure when the balance of the intake air amount between the cylinders C1 and C2 is disturbed in the direction in which the intake air amount of the cylinder C1 becomes larger than the intake air amount of the cylinder C2 due to the misalignment. (First deformation characteristic) and the normal characteristic of the communication passage intake pressure are shown. FIG. 8 shows the characteristic of the communication passage intake pressure when the balance of the intake air amount between the cylinders C1 and C2 is disturbed in the direction in which the intake air amount of the cylinder C2 becomes larger than the intake air amount of the cylinder C1 due to the misalignment. (Second deformation characteristic) and the normal characteristic of the communication passage intake pressure are shown.

When the engine system 1 is actually used, for example, a vehicle equipped with the engine system 1 is generally used, and it is assumed that such an engine system 1 is in operation. However, when the engine system 1 is actually used, this includes not only the period in which the vehicle equipped with the engine system 1 is running, but also the period in which the vehicle is stopped in the idling state. In the fuel injection amount determination method according to the embodiment of the present invention, the steps performed when the engine system 1 is actually used are executed by the ECU 45.

As shown in FIG. 5, when the engine system 1 is actually used, the ECU 45 first acquires the engine speed of the engine 11 from the detection signal output from the engine speed sensor 35 (step S11). Subsequently, the ECU 45 acquires the throttle opening of the throttle valves 18 and 19 from the detection signal output from the throttle opening sensor 20 (step S12). Subsequently, the ECU 45 acquires the gear position of the transmission from the detection signal output from the gear position sensor 39 (step S13).

Subsequently, the ECU 45 acquires the intake pressure detection value P1 (see FIG. 7 or 8) which is the communication passage intake pressure of the detection value acquisition angle A1 from the detection signal output from the intake pressure sensor 42 (step S14). ..

Subsequently, the ECU 45 determines whether the engine speed acquired in step S11 is equal to or lower than the reference speed (step S15). The reference rotation speed used here is the same as the reference rotation speed used in step S1 in FIG. When the engine speed is equal to or lower than the reference speed (step S15: YES), subsequently, the ECU 45 determines whether the throttle opening obtained in step S12 is equal to or lower than the reference opening (step S16). ). The reference opening used here is the same as the reference opening used in step S1 in FIG. When the throttle opening is equal to or less than the reference opening (step S16: YES), the ECU 45 subsequently determines whether the gear position acquired in step S13 is neutral (step S17).

When the gear position is in neutral (step S17: YES), the ECU 45 then determines from the detection signal output from the intake pressure sensor 42, the intake pressure reference value that is the communication passage intake pressure at the reference value acquisition angle A2. P0 (see FIG. 7 or 8) is acquired (step S18).

Subsequently, the ECU 45 calculates the intake pressure difference value ΔP by performing the calculation of the following mathematical expression (11) (step S19).

ΔP=P1-P0 (11)
Subsequently, the ECU 45 calculates the intake pressure calculated value P2 (see FIG. 7 or 8) by performing the calculation of the following mathematical expression (12) (step S20).

P2=P1-ΔP×2 (12)
On the other hand, when the engine speed acquired in step S11 is not lower than the reference speed (step S15: NO), the throttle opening acquired in step S12 is not lower than the reference opening (step S16: NO), or step S13. When the gear position acquired in step S21 is not neutral (step S17: NO), the ECU 45 calculates the intake pressure calculation value P2 using the previously calculated intake pressure difference value ΔP (step S21). In order to enable this process, the latest value of the intake pressure difference value ΔP calculated in step S19 is stored in the storage unit 46.

Subsequently, the ECU 45 determines the fuel injection amount of each of the cylinders C1 and C2 using the intake pressure detection value P1 acquired in step S14 and the intake pressure calculation value P2 calculated in step S20 or S21 (step S22). Specifically, the ECU 45 calculates the difference between the intake pressure detection value P1 acquired in step S14 and the atmospheric pressure value detected by the atmospheric pressure sensor 38 as the intake pressure input value for the cylinder C1. Subsequently, the ECU 45 refers to the map M1 for the cylinder C1 stored in the storage unit 46, and identifies the fuel injection valve 21 specified by the intake pressure input value for the cylinder C1 and the engine speed acquired in step S11. The fuel injection time of is read from the map M1. Further, the ECU 45 calculates the difference between the intake pressure calculation value P2 calculated in step S20 or S21 and the atmospheric pressure value detected by the atmospheric pressure sensor 38 as the intake pressure input value for the cylinder C2. Subsequently, the ECU 45 refers to the map M2 for the cylinder C2 stored in the storage unit 46, and identifies the fuel injection valve 22 specified by the intake pressure input value for the cylinder C2 and the engine speed acquired in step S11. The fuel injection time of is read from the map M2.

Thereafter, the ECU 45 controls the fuel injection time of the fuel injection valve 21 of the cylinder C1 based on the fuel injection time read from the map M1, and the fuel of the cylinder C2 based on the fuel injection amount read from the map M2. The fuel injection time of the injection valve 22 is controlled. When performing these controls, the fuel injection time of each fuel injection valve 21, 22 is determined based on the cooling water temperature detected by the water temperature sensor 37, the intake air temperature detected by the intake air temperature sensor 17, and the like. to correct.

According to the fuel injection amount determination method of the embodiment of the present invention, the fuel injection amount of the cylinder C1 and the fuel injection amount of the cylinder C2 can be determined with high accuracy as described below.

That is, as shown in FIG. 7, when the balance of the intake air amount between the cylinders C1 and C2 is destroyed due to the misalignment, the intake air amount of the cylinder C1 becomes larger than the intake air amount of the cylinder C2. , The first deformation characteristic in which the characteristic of the communication passage intake pressure is changed from the normal characteristic. In FIG. 7, the solid characteristic line shows the normal characteristic (or ideal characteristic) of the communication passage intake pressure, and the two-dot chain line characteristic curve shows the first deformation characteristic of the communication passage intake pressure.

When the characteristic of the communication passage intake pressure changes from the normal characteristic to the first deformation characteristic, the communication passage intake pressure of the detection value acquisition angle A1, that is, the intake pressure detection value P1 increases. The degree of increase of the intake pressure detection value P1 increases as the degree of imbalance in the intake air amount between the cylinders C1 and C2 increases. However, even if the characteristic of the communication passage intake pressure changes from the normal characteristic to the first deformation characteristic, the communication passage intake pressure of the reference value acquisition angle A2, that is, the intake pressure reference value P0 hardly increases or decreases. Therefore, the magnitude of the absolute value of the intake pressure difference value ΔP calculated by the above equation (11) represents the degree to which the balance of the intake air amount between both cylinders C1 and C2 is broken (the degree of synchronization deviation), That the intake pressure difference value ΔP is a positive value means that the balance of the intake air amount between the cylinders C1 and C2 collapses in the direction in which the intake air amount of the cylinder C1 becomes larger than the intake air amount of the cylinder C2 ( It indicates the direction of misalignment).

Further, as shown in FIG. 7, when the characteristic of the communication passage intake pressure becomes the first deformation characteristic due to the misalignment, the intake pressure detection value P1 is the intake pressure detection value when the misalignment does not occur. (That is, the intake pressure reference value P0) is larger by the absolute value of the intake pressure difference value ΔP. Further, in this case, the intake pressure calculation value P2 calculated by the above equation (12) is an absolute value of the intake pressure difference value ΔP more than the intake pressure calculation value (intake pressure reference value P0) when the synchronization deviation is not generated. , Becomes a small value. Therefore, by determining the fuel injection amount of the cylinder C1 on the basis of the detected intake pressure value P1 and the engine speed, the fuel injection amount of the cylinder C1 is adjusted to increase in comparison with the case where there is no misalignment. It Further, by determining the fuel injection amount of the cylinder C2 on the basis of the intake pressure calculated value P2 and the engine speed, the fuel injection amount of the cylinder C2 is adjusted in a direction in which the fuel injection amount decreases as compared with the case where there is no misalignment. It Then, the respective adjustment amounts of the fuel injection amount of the cylinder C1 and the fuel injection amount of the cylinder C2 are determined according to the magnitude of the absolute value of the intake pressure difference value ΔP.

On the other hand, as shown in FIG. 8, when the balance of the intake air amount between the cylinders C1 and C2 is destroyed in the direction in which the intake air amount of the cylinder C2 becomes larger than the intake air amount of the cylinder C1 due to the misalignment, , A second deformation characteristic in which the characteristic of the communication passage intake pressure is changed from the normal characteristic. In FIG. 8, the solid characteristic line indicates the normal characteristic (or ideal characteristic) of the communication passage intake pressure, and the two-dot chain line characteristic curve indicates the second deformation characteristic of the communication passage intake pressure.

When the characteristic of the communication passage intake pressure changes from the normal characteristic to the second deformation characteristic, the communication passage intake pressure of the detection value acquisition angle A1, that is, the intake pressure detection value P1 decreases. The degree of decrease of the intake pressure detection value P1 increases as the degree of imbalance in the intake air amount between the cylinders C1 and C2 increases. However, even if the characteristic of the communication passage intake pressure becomes the second deformation characteristic, the communication passage intake pressure of the reference value acquisition angle A2, that is, the intake pressure reference value P0 hardly increases or decreases. Therefore, the magnitude of the absolute value of the intake pressure difference value ΔP calculated by the above equation (11) represents the degree to which the balance of the intake air amount between both cylinders C1 and C2 is broken (the degree of synchronization deviation), The fact that the intake pressure difference value ΔP is a negative value means that the balance of the intake air amount between the cylinders C1 and C2 collapses in the direction in which the intake air amount of the cylinder C2 becomes larger than the intake air amount of the cylinder C1 ( It indicates the direction of misalignment).

Further, as shown in FIG. 8, when the characteristic of the communication passage intake pressure becomes the second deformation characteristic due to the misalignment, the intake pressure detected value P1 is the intake pressure detected value when the misalignment does not occur. (That is, the intake pressure reference value P0) is smaller by the absolute value of the intake pressure difference value ΔP. Further, in this case, the intake pressure calculated value P2 calculated by the above equation (12) is an absolute value of the intake pressure difference value ΔP more than the intake pressure calculated value (intake pressure reference value P0) when there is no misalignment. , A large value. Therefore, by determining the fuel injection amount of the cylinder C1 based on the intake pressure detection value P1 and the engine speed, the fuel injection amount of the cylinder C1 is adjusted so as to decrease as compared with the case where there is no misalignment. It Further, by determining the fuel injection amount of the cylinder C2 on the basis of the intake pressure calculated value P2 and the engine speed, the fuel injection amount of the cylinder C2 is adjusted in a direction in which the fuel injection amount increases as compared with the case where the misalignment does not occur. It Then, the respective adjustment amounts of the fuel injection amount of the cylinder C1 and the fuel injection amount of the cylinder C2 are determined according to the magnitude of the absolute value of the intake pressure difference value ΔP.

On the other hand, when there is no misalignment, the communication passage intake pressure characteristic becomes normal. In this case, the intake pressure detection value P1 and the intake pressure reference value P0 are the same, so the intake pressure difference value ΔP is 0, and therefore the intake pressure calculation value P2 is the same as the intake pressure detection value P1. Therefore, the fuel injection amount of the cylinder C1 and the fuel injection amount of the cylinder C2 are respectively determined based on the same communication passage intake pressure value, and as a result, the fuel injection amounts of the cylinders C1 and C2 are not adjusted.

As described above, according to the fuel injection amount determination method of the embodiment of the present invention, the degree and direction of the misalignment can be recognized, and the fuel injection amount of the cylinder C1 The fuel injection amount of the cylinder C2 can be adjusted respectively. Therefore, the fuel injection amount of each cylinder C1, C2 can be determined with high accuracy.

Further, in the fuel injection amount determination method of the embodiment of the present invention, the fuel injection amount of each cylinder C1, C2 is determined based on the communication passage intake pressure of the detected value acquisition angle A1. The detected value acquisition angle A1 is a crank angle at which the amount of change in the communication passage intake pressure with respect to the throttle operation is large compared to other crank angle ranges. Therefore, by detecting the communication passage intake pressure at the detection value acquisition angle A1, it is possible to clearly detect a change in the communication passage intake pressure due to a minute throttle operation. Therefore, the fuel injection amount of each cylinder C1, C2 according to the throttle operation can be determined with high accuracy.

Further, since the detection value acquisition range R1 to which the detection value acquisition angle A1 belongs is set to the crank angle range in which the intake valves of the cylinders C1 and C2 are both closed, the crank having a large change amount of the communication passage intake pressure with respect to the throttle operation. The angle can be reliably set as the detection value acquisition angle A1. Therefore, it is possible to surely realize highly accurate determination of the fuel injection amount of each cylinder C1, C2.

Further, according to the fuel injection determination method of the embodiment of the present invention, the communication passage intake pressure of the detected value acquisition angle A1 having a large increase/decrease range due to the synchronization deviation and the communication passage intake pressure of the reference value acquisition angle A2 having a small increase/decrease range due to the synchronization deviation. The synchronization deviation is detected based on the difference between and. Therefore, the degree and direction of the misalignment can be detected with high accuracy.

Further, in the fuel injection determination method according to the embodiment of the present invention, the intake pressure detection obtained when the engine speed is equal to or lower than the reference speed, the throttle opening is equal to or lower than the reference opening, and the gear position is neutral. The intake pressure difference value ΔP is calculated using the value P1 and the intake pressure reference value P0. When the engine speed is equal to or lower than the reference speed, the throttle opening is equal to or lower than the reference opening, and the gear position is in neutral, the engine 11 is in the idling state, fluctuations in the engine speed, and intake due to throttle operation. There is little fluctuation in atmospheric pressure. The intake pressure difference value ΔP is calculated with high accuracy by calculating the intake pressure difference value ΔP using the intake pressure detection value P1 and the intake pressure reference value P0 acquired when the operation of the engine 11 is stable. be able to. Therefore, it is possible to detect the misalignment and determine the fuel injection amount with high accuracy.

In the fuel injection amount determination method of the embodiment of the present invention, when the engine speed is not lower than the reference speed, the throttle opening is not lower than the reference opening, or the gear position is not neutral, the intake pressure difference calculated last time is calculated. The intake pressure calculation value P2 is calculated using the value ΔP. As a result, even when the operation of the engine may not be stable, the intake pressure calculation value P2 can be highly accurately calculated using the latest intake pressure difference value ΔP calculated when the engine operation was stable. Can be calculated.

In the above-described embodiment, when the engine speed is equal to or lower than the reference speed, the throttle opening is equal to or less than the reference opening, and the gear position is neutral, the following three conditions are satisfied: The case where the intake pressure reference value P0 is acquired and the intake pressure difference value ΔP is calculated has been described as an example. However, if it is possible to specify the timing at which the intake pressure reference value P0 is acquired and the intake pressure difference value ΔP can be calculated with high accuracy, any one or any two of these three condition items can be specified. When the above condition is satisfied, the intake pressure reference value P0 may be acquired and the intake pressure difference value ΔP may be calculated.

Further, in the above-described embodiment, the intake pressure difference value ΔP is stored in the storage unit 46, and when the engine speed is not lower than the reference speed, the throttle opening is not lower than the reference opening, or the gear position is not neutral. In some cases, the intake pressure difference value ΔP stored in the storage unit 46 is used as the previously calculated intake pressure difference value ΔP to calculate the intake pressure calculated value P2. However, the intake pressure detection value P1 and the intake pressure reference value P0 acquired in the same operation cycle are stored in the storage unit 46, and when the engine speed is not lower than the reference speed, the throttle opening is lower than the reference opening. If not, or if the gear position is not neutral, the previous intake pressure difference value ΔP is calculated using the intake pressure detection value P1 and the intake pressure reference value P0 stored in the storage unit 46, and the previous intake pressure difference value ΔP is calculated. The intake pressure calculation value P2 may be calculated using this.

Further, the calculation method of the intake pressure calculated value using the mathematical expression (1) in the above-described embodiment and the calculation method of the intake pressure calculated value using the mathematical expressions (11) and (12) in the above-described embodiments are examples. Therefore, the intake pressure calculation value may be calculated using another mathematical expression.

Further, in the above-described embodiment, the engine 11 in which the phase of the operation cycle of the cylinder C2 is delayed by 270 degrees with respect to the phase of the operation cycle of the cylinder C1 is taken as an example. However, the phase difference of the operation cycle between the cylinders may be different from each other, and the magnitude of the phase difference is not limited.

Further, the cylinders of the engine 11 to which the fuel injection amount determination method and the fuel injection amount determination device of the present invention can be applied may be arranged in series, in parallel, in a V-shape, in a horizontal plane, or in any other arrangement. Also, the inclination angle of each cylinder is not limited.

Further, although the intake passages 13 and 14 of the above-described embodiment have their upstream ends separated from each other, the upstream ends of the two intake passages may be joined. In this case, the throttle valve may be arranged at the portion where the two intake passages merge. It should be noted that in the case of such a configuration, the intake pressure can be detected at the portion where the two intake passages merge, but this may be difficult due to various circumstances. In such a case, the fuel injection amount of each cylinder can be determined with high accuracy by applying the present invention.

Further, the fuel injection amount determination method and the fuel injection amount determination device of the present invention can be widely applied to engine systems for four-wheeled vehicles, two-wheeled vehicles, ships, and the like.

Further, the present invention can be appropriately modified without departing from the scope or spirit of the invention that can be read from the claims and the entire specification, and the fuel injection amount determination method and the fuel injection amount determination that involve such changes. The device is also included in the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 1 engine system 11 engine 13, 14 intake passage 18, 19 throttle valve 20 throttle opening sensor 21, 22 fuel injection valve (fuel injection device)
35 engine speed sensor 39 gear position sensor 41 communication passage 42 intake pressure sensor 45 ECU (arithmetic processing unit)
46 Memory C1, C2 Cylinder M1, M2 Map

Claims (4)

An engine having a first cylinder and a second cylinder having a phase difference in operation cycle, a first intake passage and a second intake passage for supplying air to the first cylinder and the second cylinder, respectively. , A first fuel injection device and a second fuel injection device that respectively supply fuel to the first cylinder and the second cylinder, and the first intake passage and the second intake passage are communicated with each other. The first fuel is used in an engine system including a communication passage and an intake pressure sensor that detects a communication passage intake pressure that is an intake pressure in the communication passage, and the first fuel is based on the communication passage intake pressure and the engine speed. A fuel injection amount determination method for determining a fuel injection amount of an injection device and a fuel injection amount of the second fuel injection device, respectively.
In one operation cycle period, a crank angle range in which both the intake valve of the first cylinder and the intake valve of the second cylinder are closed is specified as a detection value acquisition range,
In the one operation cycle period, the crank angle range in which the intake valve of the first cylinder or the intake valve of the second cylinder is opened is specified as the reference value acquisition range,
When the characteristic of the communication passage intake pressure is normal, the crank angle within the detection value acquisition range and the crank angle within the reference value acquisition range where the communication passage intake pressure is the same are detected value acquisition angle and reference value. Specify the acquisition angle in advance,
In the one operation cycle period, the communication passage intake pressure of the detection value acquisition angle is acquired as an intake pressure detection value, and the communication passage intake pressure of the reference value acquisition angle is acquired as an intake pressure reference value,
The intake pressure calculated by determining the fuel injection amount of the first fuel injection device based on the intake pressure detection value and the engine speed, and using the difference between the intake pressure detection value and the intake pressure reference value. A fuel injection amount determination method, characterized in that the fuel injection amount of the second fuel injection device is determined based on a calculated value and the engine speed. The intake pressure calculation value is calculated using the difference between the intake pressure detection value and the intake pressure reference value acquired when all the predetermined condition items are satisfied, and the condition item is that the transmission is in neutral. The engine speed is equal to or lower than a reference speed, and the throttle opening is equal to or lower than a reference opening, or any two or all of them. The method for determining the fuel injection amount according to claim 1. When at least one of the condition items is not satisfied, the difference between the intake pressure detection value and the intake pressure reference value acquired in the past time when all of the condition items are satisfied, and the current acquisition The fuel injection amount determination method according to claim 2, wherein the intake pressure calculated value is calculated using the detected intake pressure value. An engine having a first cylinder and a second cylinder having a phase difference in operation cycle, a first intake passage and a second intake passage for supplying air to the first cylinder and the second cylinder, respectively. , A first fuel injection device and a second fuel injection device that respectively supply fuel to the first cylinder and the second cylinder, and the first intake passage and the second intake passage are communicated with each other. The first fuel is used in an engine system including a communication passage and an intake pressure sensor that detects a communication passage intake pressure that is an intake pressure in the communication passage, and the first fuel is based on the communication passage intake pressure and the engine speed. A fuel injection amount determination device that determines a fuel injection amount of an injection device and a fuel injection amount of the second fuel injection device, respectively.
A storage unit and an arithmetic processing unit are provided,
A crank angle range in which both the intake valve of the first cylinder and the intake valve of the second cylinder are closed within one operation cycle period is referred to as a detection value acquisition range. If the crank angle range in which the intake valve of the cylinder is open or the intake valve of the second cylinder is opened is referred to as a reference value acquisition range, the communication passage intake pressures are the same when the characteristics of the communication passage intake pressure are normal. The crank angle in the detection value acquisition range and the crank angle in the reference value acquisition range are respectively stored in the storage unit as a detection value acquisition angle and a reference value acquisition angle,
The arithmetic processing unit acquires the communication passage intake pressure of the detection value acquisition angle stored in the storage unit as an intake pressure detection value within the one operation cycle period, and acquires the reference value stored in the storage unit. Obtaining the communication passage intake pressure of the corner as the intake pressure reference value,
The intake pressure calculated by determining the fuel injection amount of the first fuel injection device based on the intake pressure detection value and the engine speed, and using the difference between the intake pressure detection value and the intake pressure reference value. A fuel injection amount determination device, which determines a fuel injection amount of the second fuel injection device based on a calculated value and the engine speed.

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