JP5195226B2 - Fuel injection device - Google Patents

Description

  The present invention relates to a fuel injection device applied to an internal combustion engine provided with two intake valves that can be opened and closed with different lift amounts for one cylinder.

  A fuel injection valve that is provided in each of the two intake ports communicating with the combustion chamber and injects fuel into the intake air flowing through the intake port, and the fuel injection amount for each fuel injection valve according to the flow rate of the intake air flowing through the intake port. There is known a fuel injection device including an injection amount control means for controlling (Patent Document 1). In addition, Patent Documents 2 and 3 exist as prior art documents related to the present invention.

JP 2007-292058 A Japanese Utility Model Publication No. 2007-291978 JP 2008-111342 A

  In an internal combustion engine provided with two intake valves that can be opened and closed with different lift amounts for one cylinder, the lift amount of one intake valve is made smaller than the other for the purpose of promoting turbulence in the air flow in the cylinder. It may cause a difference in intake airflow between ports. In this case, if the same amount of fuel is injected into each intake port from the fuel injection valve provided for each intake port, the fuel concentration differs for each intake port. Deterioration may be caused and the generation amount of hydrocarbon (HC) and carbon monoxide (CO) may increase.

  Therefore, an object of the present invention is to provide a fuel injection device that can improve the homogeneity of the fuel concentration in the cylinder.

The fuel injection device for a first internal combustion engine of the present invention is provided with a fuel injection applied to an internal combustion engine in which two intake ports are provided for one cylinder and the intake valve of each intake port can be opened and closed with different lift amounts. In the apparatus, the larger the lift amount difference between the fuel injection valve provided for each intake port and the intake valve, the larger the fuel injection amount ratio of the two intake ports on the side where the lift amount of the intake valve is larger Fuel injection control means for controlling the fuel injection amount for each fuel injection valve so as to increase, and a throttle valve capable of adjusting the intake air amount is provided upstream of the intake port, and the fuel injection control The means corrects the fuel injection amount ratio based on the opening degree of the throttle valve, and is biased toward the air flow guided to the cylinder via the intake port downstream of the throttle valve and upstream of the intake port. Airflow control valve is provided to impart, said fuel injection control means takes into account the degree of opening of the air flow control valve when the correction of the fuel injection amount ratio on the basis of the opening degree of the throttle valve ( Claim 1).

  According to this fuel injection device, the fuel injection amount for each fuel injection valve is controlled such that the larger the lift amount difference between the intake valves of the two intake ports, the larger the fuel injection amount ratio on the side where the lift amount is larger. The As the lift amount of the intake valve increases, the flow rate of the intake air flowing through the intake port increases. Therefore, the fuel concentration of the air-fuel mixture flowing from each intake port to the cylinder can be made uniform by increasing the fuel injection amount ratio on the side where the lift amount is large in accordance with the lift amount difference between the intake valves. Thereby, since the air-fuel mixture having a uniform fuel concentration flows from each intake port into the cylinder, the homogeneity of the fuel concentration in the cylinder can be improved.

Further, even in the lift amount of the intake valves are the same, the amount of fuel required for the fuel density uniformity between the two intake ports when the amount of intake air is changed is changed. For this reason, the fuel concentration between the two intake ports may not be uniform only by increasing the fuel injection amount ratio on the side where the lift amount is large according to the lift amount difference. According to this fuel injection device , since the fuel injection amount ratio is corrected based on the opening degree of the throttle valve, the fuel concentration between the intake ports can be made uniform in accordance with the change in the intake amount.

Furthermore, in the case of this, when correcting the fuel injection amount ratio, because the flow rate of intake air in each intake port which varies in accordance with the opening degree of the air flow control valve is taken into account, to correct the fuel injection amount ratio more accurately Can do.

The fuel injection device for a second internal combustion engine of the present invention is provided with a fuel injection applied to an internal combustion engine in which two intake ports are provided for one cylinder and the intake valve of each intake port can be opened and closed with different lift amounts. In the apparatus, the larger the lift amount difference between the fuel injection valve provided for each intake port and the intake valve, the larger the fuel injection amount ratio of the two intake ports on the side where the lift amount of the intake valve is larger Fuel injection control means for controlling the fuel injection amount for each fuel injection valve so as to increase, and a throttle valve capable of adjusting the intake air amount is provided upstream of the intake port, and the fuel injection control means, based on the opening degree of the throttle valve to correct the fuel injection amount ratio, said internal combustion engine is provided in the exhaust gas recirculation passage and exhaust gas recirculation passage connecting the exhaust passage and upstream of the intake port An exhaust gas recirculation device having an exhaust gas recirculation valve is provided, and the fuel injection control means adjusts the opening degree of the exhaust gas recirculation valve when correcting the fuel injection amount ratio based on the opening degree of the throttle valve. In consideration of this, the fuel injection amount for each fuel injection valve may be controlled (Claim 2 ). According to the second fuel injection device of the present invention, in correcting the fuel injection amount ratio, the flow rate of the intake air in each intake port that changes according to the amount of exhaust gas recirculated to the intake passage is considered. The fuel injection amount ratio can be corrected accurately.

In one aspect of the first and second fuel injection devices of the present invention, the fuel injection control means is configured to cause a predetermined fuel concentration difference between the two intake ports when stratified combustion is performed in the cylinder. the may control the fuel injection amount of each fuel injection valve (claim 3). In this case, a predetermined fuel concentration difference can be generated between the fuel concentrations flowing into the cylinder from the two intake ports. Thereby, since the stratified region can be intentionally created, stratified combustion in the cylinder can be promoted.

In one aspect of the first and second fuel injection devices of the present invention, the fuel injection control means includes a fuel injection amount per time for each fuel injection valve so that a fuel injection period for each fuel injection valve becomes equal. May be controlled (claim 4 ). According to this aspect, the fuel injection period of each fuel injection valve can be made equal regardless of the amount of fuel injection. Thereby, since the mixing period of the fuel and air in each intake port becomes equal, compared with the case where this period differs between intake ports, the homogeneity of the fuel concentration in a cylinder can be raised.

  As described above, according to the present invention, the larger the lift amount difference between the intake valves of the two intake ports, the larger the fuel injection amount ratio on the side where the lift amount of the intake valve is larger. The fuel injection amount is controlled. As a result, the fuel concentration of the air-fuel mixture flowing from each intake port to the cylinder can be made uniform, so that the homogeneity of the fuel concentration in the cylinder can be improved.

(First form)
FIG. 1 is an explanatory view schematically showing a main part of an internal combustion engine to which a fuel injection device according to a first embodiment of the present invention is applied. The internal combustion engine 1A is configured as an in-line four-cylinder internal combustion engine in which four cylinders 2 (only one is shown in FIG. 1) are arranged in one direction. An intake passage 3 and an exhaust passage 4 are connected to each cylinder 2. The intake passage 3 has intake ports 3 a and 3 b that are branched for each cylinder 2 and are provided for each cylinder 2. A throttle valve 6 capable of adjusting the intake air amount is provided upstream of each intake port 3a, 3b. The exhaust passage 4 has two exhaust ports 4 a and 4 b provided for each cylinder 2. A piston (not shown) is inserted into each cylinder 2 in a state where it can reciprocate. Each cylinder 2 is provided with a spark plug (not shown) so that its electrode portion protrudes into the cylinder 2.

  One intake valve 10 is provided in each intake port 3a, 3b. The internal combustion engine 1A is provided with an electromagnetic drive device 11 for opening and closing each intake valve 10. The electromagnetic drive device 11 is a known device that can freely set the valve operating characteristics such as the operating angle, lift amount, and phase of each intake valve 10, and can open and close each intake valve 10 with different lift amounts. The operation of the electromagnetic drive device 11 is controlled by an engine control unit (ECU) 15 configured as a computer for appropriately controlling the operating state of the internal combustion engine 1A. Further, a fuel injection valve 16a is provided in the upper intake port 3a in FIG. 1, and a fuel injection valve 16b is provided in the lower intake port 3b. The fuel injection operation of each fuel injection valve 16a, 16b is controlled by the ECU 15.

  The ECU 15 controls the operation of the electromagnetic drive device 11 and the operations of the fuel injection valves 16a and 16b according to a predetermined program while referring to signals output from various sensors (not shown). As an example, the ECU 15 makes the lift amount between the intake valves 10 of the intake ports 3a and 3b different from each other when it is desired to promote the turbulence of the air flow in the cylinder 2 such as when the internal combustion engine 1A is operating at a low speed. The operation of the electromagnetic drive device 11 is controlled. As a result, the velocity distribution of the airflow taken into the cylinder 2 is biased, and the turbulence of the airflow is promoted. On the other hand, when there is no need to promote airflow turbulence in the cylinder 2, the ECU 15 controls the operation of the electromagnetic drive device 11 so that the lift amounts between the intake valves 10 of the intake ports 3a and 3b are equal to each other.

  FIG. 2 is a flowchart showing an example of a fuel injection amount control routine executed by the ECU 15. A program for this routine is stored in the ECU 15 and is read out in a timely manner and repeatedly executed at predetermined intervals. In step S1, the ECU 15 calculates a target fuel injection amount to be injected per cycle according to the operating state of the internal combustion engine 1A. The target fuel injection amount is calculated based on the engine speed and intake air amount of the internal combustion engine 1A acquired based on a sensor (not shown). The calculation of the target fuel injection amount is realized, for example, by presetting a map that gives the target fuel injection amount with the engine speed and the intake air amount as variables and referring to the map.

  Next, in step S2, the lift amount difference between the intake valves 10 is calculated based on the lift amount information of each intake valve 10 instructed to the electromagnetic drive device 11, and the target fuel injection amount is calculated for each fuel injection based on the lift amount difference. A fuel injection amount ratio for separately blowing by the valves 16a and 16b is calculated. FIG. 3 shows the relationship between the lift amount difference and the fuel injection amounts of the fuel injection valves 16a and 16b. As shown in FIG. 3, when there is no difference in lift amount, the fuel injection amounts of both fuel injection valves 16a and 16b are equal. As the lift amount difference changes from small to large, the fuel injection amount of the fuel injection valve 16b with a large lift amount increases, and conversely, the fuel injection amount of the fuel injection valve 16a with a small lift amount decreases. In other words, the larger the lift amount difference, the larger the fuel injection amount ratio of the fuel injection valve 16b with the larger lift amount, and the smaller the fuel injection amount ratio of the fuel injection valve 16a with the smaller lift amount. In step S2, the fuel injection amount ratio is calculated by referring to a map that provides the fuel injection amount ratios of the fuel injection valves 16a and 16b with the lift amount difference indicating the relationship shown in FIG. .

  In step S3, the opening information of the throttle valve 6 is acquired from a sensor (not shown) provided in the throttle valve 6, and each fuel injection valve 16a calculated in step S2 based on the acquired opening information of the throttle valve 6; The fuel injection amount ratio of 16b is corrected. The correction in step S3 is realized by calculating a correction coefficient by referring to a map that gives a correction coefficient with the opening degree of the throttle valve 6 as a variable, and multiplying the fuel injection amount ratio calculated in step S2 by this correction coefficient. The In the map to which this correction coefficient is given, the fuel injection amount ratio calculated in step S2 is made to correspond to the opening of the throttle valve 6, and the fuel injection between the two intake ports 3a, 3b is made uniform. A correction coefficient for correcting the quantity ratio is set. FIG. 4 is a diagram showing an example of a map that gives the fuel injection amount ratio of the fuel injection valve 16a with the lift amount difference as a variable. FIG. 4 shows the relationship between the lift amount difference after the fuel injection amount ratio calculated in step S2 is corrected in step S3 and the fuel injection amount ratio of the fuel injection valve 16a. As shown in FIG. 4, the fuel injection amount ratio calculated in step S <b> 2 is corrected as indicated by a solid line 17 when the opening degree of the throttle valve 6 is large by executing step S <b> 3, and the throttle valve 6 is opened. As the degree decreases, correction is performed as indicated by a one-dot chain line 18 and a broken line 19.

  In step S4, the fuel injection amount for each of the fuel injection valves 16a and 16b is calculated by multiplying the target fuel injection amount calculated in step S1 by the fuel injection amount ratio corrected in step S3. In step S5, the fuel injection operation of each fuel injection valve 16a, 16b is controlled so that the fuel injection amount of each fuel injection valve 16a, 16b calculated in step S4 is injected, and the current routine ends. The injection rate (fuel injection amount per time) in step S5 is set so that the injection periods of the fuel injection valves 16a and 16b are equal.

  The ECU 15 executes the routine of FIG. 2 so that the larger the lift amount difference between the intake valves 10 provided in the two intake ports 3a and 3b, the larger the fuel injection amount ratio on the side with the larger lift amount. The fuel injection amount of each fuel injection valve 16a, 16b is controlled. As the lift amount of the intake valve 10 increases, the flow rate of the intake air flowing through the intake ports 3a and 3b increases. Therefore, the fuel concentration of the air-fuel mixture flowing from the intake ports 3a and 3b to the cylinder 2 is made uniform by increasing the fuel injection amount ratio on the side where the lift amount is large according to the lift amount difference between the intake valves 10. be able to. In addition, since the air-fuel mixture having a uniform fuel concentration flows from the intake ports 3a and 3b into the cylinder 2, the homogeneity of the fuel concentration in the cylinder 2 can be improved. The ECU 15 functions as fuel injection control means according to the present invention by executing the routine of FIG.

  2 is corrected by the ECU 15 according to the opening degree of the throttle valve 6, the fuel injection amount ratio between the fuel injection valves 16a and 16b is corrected. The amount of intake air flowing through the intake passage 3 changes according to the opening of the throttle valve 6. Even if the lift amount of the intake valve 10 is the same, if the intake amount flowing through the intake passage 3 changes, the fuel amount necessary to make the fuel concentration between the two intake ports 3a, 3b uniform will change. For this reason, the fuel concentration between the intake ports 3a and 3b may not be uniform only by calculating the fuel injection amount ratio according to the lift amount difference. However, according to this embodiment, by executing the routine of FIG. 2, it is possible to correct the fuel injection amount ratio between the fuel injection valves 16a and 16b corresponding to the change in the intake air amount. Accordingly, even if the flow rate of the intake air flowing through the intake ports 3a and 3b changes according to the opening of the throttle valve 6, the fuel concentration between the intake ports 3a and 3b can be made uniform.

  In step S4 of FIG. 2, the injection rates of the fuel injection valves 16a and 16b are set so that the fuel injection periods of the fuel injection valves 16a and 16b are equal. 5 and 6 schematically show the relationship between the injection rate and the fuel injection period. FIG. 5 shows the case where the fuel injection valves 16a and 16b have the same injection rate, and FIG. 6 shows each fuel injection valve 16a. 16b show the cases where the fuel injection period is made equal. The fuel injection period of each fuel injection valve 16a, 16b is set within the intake period in which each intake port 3a, 3b is opened. As shown in FIG. 5, when the injection rates U1 and U2 of the two fuel injection valves 16a and 16b having different fuel injection amounts are equal, the fuel injection amount is small during the injection period T1 of the fuel injection valve 16a where the fuel injection amount is large. This is shorter than the injection period T2 of the valve 16b. On the other hand, in FIG. 6, the injection rate of each fuel injection valve 16a, 16b is lowered according to the fuel injection amount. That is, the injection rate U1 of the fuel injection valve 16a with a small injection amount is lower than the injection rate U2 of the fuel injection valve 16b with a large injection amount. Thus, by setting the injection rate according to the fuel injection amount, the fuel injection periods of the fuel injection valves 16a and 16b can be made equal regardless of the amount of fuel injection. As a result, the mixing period of the fuel and the air in each intake port 3a, 3b becomes equal, so the homogeneity of the fuel concentration in the cylinder 2 is different from the case of FIG. Can be increased.

(Second form)
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 7 is an explanatory view schematically showing a main part of the internal combustion engine 1B to which the fuel injection device according to the second embodiment of the present invention is applied. Below, the same code | symbol is attached | subjected to FIG. 7 for the structure common to a 1st form, and description is abbreviate | omitted.

  As shown in FIG. 7, in the second embodiment, a tumble control valve (as an air flow control valve) that generates a tumble flow in the air flow guided to the cylinder 2 via the intake ports 3a and 3b upstream of the intake ports 3a and 3b. TCV) 20 is provided. The TCV 20 can impart a bias to the airflow such that the flow velocity on the upper side of each intake port 3a, 3b is increased by setting the opening degree to the closed side. Therefore, a tumble flow that turns in the longitudinal direction in the cylinder 2 is formed. Since the strength of the tumble flow depends on this bias, the bias increases as the TCV 20 is closed, and the strength of the tumble flow increases.

  The opening degree of the TCV 20 is controlled by the ECU 15. The ECU 15 controls the opening degree of the TCV 20 so as to generate a necessary tumble flow according to the operating state of the internal combustion engine 1B. In this case, the ECU 15 acquires the opening information of the TCV 20 from a sensor (not shown) provided in the TCV 10, and considers the opening of the TCV 20 when correcting the fuel injection amount ratio in step S3 based on the opening information. . Since the TCV 20 affects the flow rate of each intake port 3a, 3b depending on the opening, the mixture of the air-fuel mixture accompanying the change in the opening of the TCV 20 is corrected by correcting the fuel injection amount ratio according to the degree of the influence. Deterioration of the degree can be prevented. Thereby, more accurate correction of the fuel injection amount ratio can be realized. Such correction can be realized, for example, by multiplying the fuel injection amount ratio corrected in step S3 of FIG. 2 by a correction coefficient calculated according to the opening of the TCV 20.

(Third form)
Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 8 is an explanatory view schematically showing a main part of the internal combustion engine 1C to which the fuel injection device according to the third embodiment of the present invention is applied. Below, the same code | symbol is attached | subjected to FIG. 8 about the structure common to a 1st form, and description is abbreviate | omitted.

  As shown in FIG. 8, in the third embodiment, the internal combustion engine 1 </ b> C includes an exhaust gas recirculation device 30. The exhaust gas recirculation device 30 can adjust the exhaust gas recirculation passage 31 connected downstream of the throttle valve 6 and upstream of the intake ports 3a and 3b, and the amount of exhaust gas provided in the exhaust gas recirculation passage 31 and recirculated to the intake air passage 3. And an exhaust gas recirculation valve 32.

  The opening degree of the exhaust gas recirculation valve 32 is controlled by the ECU 15 in accordance with the operating state of the internal combustion engine 1C. In this case, the ECU 15 acquires the opening degree information of the exhaust gas recirculation valve 32 from a sensor (not shown) provided in the exhaust gas recirculation valve 32, and performs exhaust when correcting the fuel injection amount ratio in step S3 based on the opening degree information. The opening degree of the recirculation valve 32 is taken into consideration. Since the exhaust recirculation valve 32 changes the flow rate of each intake port 3a, 3b depending on its opening, even if the fuel injection amount ratio is corrected according to the opening of the throttle valve 6, the opening of the exhaust recirculation valve 32 does not change. If it changes, it may deviate from the appropriate value. Therefore, by correcting the fuel injection amount ratio in accordance with the flow rate change accompanying the change in the opening degree of the exhaust gas recirculation valve 32, the deterioration of the homogeneity of the air-fuel mixture accompanying the change in the opening degree of the exhaust gas recirculation valve 32 can be prevented. . Thereby, more accurate correction of the fuel injection amount ratio can be realized. Such correction can be realized, for example, by multiplying the fuel injection amount ratio corrected in step S3 of FIG. 2 by a correction coefficient calculated in accordance with the opening degree of the exhaust gas recirculation valve 32.

  However, the present invention is not limited to the above-described embodiments, and can be implemented in various forms within the scope of the gist of the present invention. In each of the above embodiments, the fuel injection amount and the injection rate are controlled so that the fuel concentration of the air-fuel mixture flowing from each intake port into the cylinder becomes uniform. However, when stratified combustion is promoted in the cylinder, The routine 2 may not be executed. In this case, a predetermined fuel concentration difference can be generated between the fuel concentrations flowing into the cylinder from the two intake ports. Thereby, since the stratified region can be intentionally created, stratified combustion in the cylinder can be promoted. Further, the fuel injection amount control routine executed by the ECU 15 is not limited to the routine shown in FIG. For example, in the routine of FIG. 2, the fuel injection amount ratio is corrected by multiplying the fuel injection amount ratio calculated in step 2 by a correction coefficient in step 3, but the present invention is not limited to such a correction method. For example, as shown in FIG. 4, a map that provides a fuel injection amount ratio corrected according to the opening degree of the throttle valve 6 using a lift amount difference as a variable is prepared in advance, and the corrected map is referred to in step S2 with reference to this map. The fuel injection amount ratio may be obtained. In this case, since the fuel injection amount ratio corresponding to the opening of the throttle valve 6 can be calculated in step S2, step S3 can be omitted. In the third embodiment, the TCV 20 is provided in the intake passage 3 as an airflow control valve. However, the present invention is not limited to this. For example, a swirl control valve (SCV) may be provided as an airflow control valve. .

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically the principal part of the internal combustion engine to which the fuel-injection apparatus which concerns on the 1st form of this invention was applied. The flowchart which shows an example of the fuel injection amount control routine which ECU which concerns on this invention performs. The figure which showed the relationship between lift amount difference and the fuel injection amount of each fuel injection valve. The figure which shows an example of the map which gives the fuel injection amount ratio of the fuel injection valve correct | amended according to the throttle opening by making a lift amount difference into a variable. The figure which showed typically the relationship between the injection rate and injection period when the injection rate is made equal for each fuel injection valve. The figure which showed typically the relationship between the injection rate and injection period when the fuel injection period of each fuel injection valve is made equal. Explanatory drawing which showed typically the principal part of the internal combustion engine to which the fuel-injection apparatus which concerns on the 2nd form of this invention was applied. Explanatory drawing which showed typically the principal part of the internal combustion engine to which the fuel-injection apparatus which concerns on the 3rd form of this invention was applied.

Explanation of symbols

1A Internal combustion engine 2 Cylinders 3a, 3b Intake port 10 Intake valve 15 ECU (fuel injection control means)
16a, 16b Fuel injection valve

Claims (4)

In a fuel injection device applied to an internal combustion engine in which two intake ports are provided for one cylinder and an intake valve of each intake port can be opened and closed with different lift amounts,
A fuel injection valve provided for each intake port;
The fuel injection amount for each fuel injection valve is controlled such that the larger the lift amount difference between the intake valves, the larger the fuel injection amount ratio of the two intake ports on the side where the intake valve lift amount is larger. Fuel injection control means for
A throttle valve capable of adjusting the intake air amount is provided upstream of the intake port,
The fuel injection control means corrects the fuel injection amount ratio based on the opening of the throttle valve,
An airflow control valve is provided downstream of the throttle valve and upstream of the intake port to impart a bias to the airflow guided to the cylinder via the intake port,
The fuel injection control device takes into account the opening of the airflow control valve when correcting the fuel injection amount ratio based on the opening of the throttle valve . In a fuel injection device applied to an internal combustion engine in which two intake ports are provided for one cylinder and an intake valve of each intake port can be opened and closed with different lift amounts,
A fuel injection valve provided for each intake port;
The fuel injection amount for each fuel injection valve is controlled such that the larger the lift amount difference between the intake valves, the larger the fuel injection amount ratio of the two intake ports on the side where the intake valve lift amount is larger. Fuel injection control means for
A throttle valve capable of adjusting the intake air amount is provided upstream of the intake port,
The fuel injection control means corrects the fuel injection amount ratio based on the opening of the throttle valve,
The internal combustion engine is provided with an exhaust gas recirculation device having an exhaust gas recirculation passage connecting the exhaust passage and the upstream of the intake port, and an exhaust gas recirculation valve provided in the exhaust gas recirculation passage,
The fuel injection control device takes into account the opening of the exhaust gas recirculation valve when correcting the fuel injection amount ratio based on the opening of the throttle valve. Said fuel injection control means, according to claim 1 or 2 for controlling the fuel injection amount of each fuel injection valve so that a predetermined fuel concentration difference occurs between the two intake ports in the case of stratified charge combustion within the cylinder The fuel injection device described in 1. The fuel according to any one of claims 1 to 3 , wherein the fuel injection control means controls a fuel injection amount per time for each fuel injection valve so that a fuel injection period for each fuel injection valve becomes equal. Injection device.

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