JPH11210477A - Intake air temperature controlling device for cylinder injection type engine incorporating supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the temperature of intake-air from lowering during stratified charge combustion so as to improve the combustion efficiency. SOLUTION: The upstream and downstream of an intercooler 12 incorporated in an intake-air passage 4, are communicated with each other by means of a bypass passage 13, and a flow change-over valve 14 is incorporated in a branch port of the bypass passage 13. During stratified charge combustion, the upstream of the intercooler 12 is closed by the flow change-over valve 14 so as to supply intake-air into a combustion chamber by way of the bypass passage 13. Since the intake-air is fed, bypassing the intercooler 12 during stratified charge combustion, the lowering of the temperature of the intake-air is restrained, thereby it is possible to improve the combustion efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake air temperature control apparatus for a direct injection engine with a supercharger, which variably sets the temperature of intake air supplied to a combustion chamber according to a combustion mode.

[0002]

2. Description of the Related Art As is well known, the combustion of a gasoline direct injection engine is easily affected by the intake air temperature because fuel is directly injected into a combustion chamber. For example, in stratified charge combustion with a high combustion improvement rate, setting the intake air temperature high increases the compressed air temperature and promotes fuel atomization, thereby improving combustion stability and reducing HC and CO emissions. Reduced. On the other hand, in the operation region where power is required, since the combustion mode is uniform combustion, the charging efficiency is increased by lowering the intake air temperature, and high engine output characteristics are obtained.

A technique for switching the combustion mode of a direct injection engine between stratified combustion and uniform combustion in accordance with the state is disclosed in Japanese Patent Application Laid-Open No. Hei 7-16692, filed earlier by the present applicant.
Since it is described in detail in Japanese Patent Publication No. 7, the description here is omitted.

[0004]

However, many of the direct injection engines provided with a supercharger also have an intercooler for lowering the intake air temperature during uniform combustion. However, the temperature of the intake air is lowered by the intercooler, and the combustion improvement rate cannot be further increased.

In particular, since the intercooler also lowers the temperature of intake air during warm-up operation, the operable area of stratified combustion is narrowed during warm-up operation, so that not only the combustion improvement rate is reduced, but also fuel efficiency is reduced. Gets worse.

In view of the above circumstances, the present invention has a wide operable region by stratified combustion, which not only improves the fuel efficiency, but also increases the combustion improvement rate of the in-cylinder injection engine with a supercharger. It is an object to provide a temperature control device.

[0007]

According to a first aspect of the present invention, there is provided a first direct-injection engine with a supercharger having a supercharger and an intercooler in an intake passage. When the injector is directly facing the combustion chamber, a bypass passage communicating the upstream and downstream of the intercooler is connected to the intake passage. A flow path switching valve is provided for guiding the intake air toward the intercooler during uniform combustion.

[0008] A second intake temperature control apparatus for a direct injection engine with a supercharger includes a supercharger and an intercooler in an intake passage, and an injector directly facing a combustion chamber. A bypass passage connecting the upstream and downstream of the intercooler is connected to the passage, and when the combustion mode is stratified combustion and the warm-up operation is completed, the intake air is guided to the bypass passage so as to perform uniform combustion. Alternatively, a flow path switching valve for guiding the intake air toward the intercooler during the warm-up operation is provided.

In the first intake temperature control apparatus for a direct injection engine with a supercharger, when the combustion mode is stratified combustion, the intake air is guided to the combustion chamber through a bypass passage bypassing an intercooler by a flow path switching valve. When the combustion mode is uniform, the intake air that has passed through the intercooler is guided to the combustion chamber by the flow path switching valve.

In the second intake air temperature control apparatus for a direct injection engine with a supercharger, when the combustion mode is a stratified charge combustion or a warm-up operation, the flow passage switching valve passes through a bypass passage that bypasses an intercooler. The intake air is guided to the combustion chamber, and when the warm-up operation is completed and the combustion mode is uniform combustion, the intake air after passing through the intercooler is guided to the combustion chamber by the flow path switching valve.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 5 show a first embodiment of the present invention.

Reference numeral 1 in FIGS. 1 and 2 denotes an in-cylinder injection engine with a supercharger, and an intake port 1a of the in-cylinder injection engine 1.
Are collected in an air chamber 3 via an intake manifold 2, and an intake passage 4 is communicated upstream of the air chamber 3.

An air cleaner 5 is attached to an air intake of the intake passage 4.
The compressor 6a of the turbocharger 6 is interposed midway. Further, a turbine 6 b of the turbocharger 6 is provided in an exhaust passage 8 that communicates with an exhaust port 1 b of the engine 1 via an exhaust manifold 7. Note that reference numeral 9
Is a catalyst and 10 is a muffler.

A throttle valve 11 is provided upstream of the air chamber 3 in the intake passage 4, and an intercooler 12 is provided upstream of the throttle valve 11. Further, a bypass passage 13 that connects the upstream and downstream of the intercooler 12 is connected to the intake passage 4.

A passage switching valve 14 is provided at a branch of the bypass passage 13 of the intake passage 4. The flow path switching valve 14 selectively switches the flow path of the intake air between the intercooler 12 and the bypass passage 13, and when energized (ON), as shown in FIG. When the power is off (OFF), the intercooler 12 is opened as shown in FIG. As shown in FIG. 3, the in-cylinder high-pressure injector 15 faces the combustion chamber 1a of each cylinder formed in the engine 1.

The switching operation of the flow path switching valve 14 is controlled by a control device (ECU) 21 shown in FIG. An input side of the control device 21 is connected to a crank angle sensor 22, a load detection unit 23, a cooling water temperature sensor 24, and the like as engine operating state detecting means, and the output side is connected to the flow path switching valve 14. I have. The load detecting means 2
As 3, there are a throttle opening sensor, an intake air amount sensor, and the like, and an accelerator opening sensor or an intake pipe pressure sensor may be used instead of the throttle opening sensor or the intake air amount sensor.

Hereinafter, a flow path switching valve control routine executed by the control device 21 will be described with reference to a flowchart shown in FIG. First, in step S1, the engine speed calculated based on the output signal of the crank angle sensor 22, and the parameters indicating the engine load, such as the throttle opening and the intake air amount calculated based on the output signal from the load detecting means 23. Based on the above, the operating state of the engine is checked.

Next, in step S2, it is determined whether the combustion mode is stratified combustion or uniform combustion based on the operation state.

In the case of stratified combustion, step S3
Then, the flow path switching valve 14 is turned ON to exit the routine.

Then, as shown in FIG. 1, the flow path switching valve 14 closes the upstream of the intercooler 12 and opens the bypass passage 13, so that the intake air introduced into the intake passage 4 Through the passage 13, the air is guided to the upstream of the throttle valve 11, bypassing the intercooler 12. As a result, since the intake air is not cooled by the intercooler 12, a decrease in the temperature of the intake air supplied to the combustion chamber 1a is suppressed, good combustion can be obtained, and not only exhaust emission can be reduced. Thus, occurrence of torque shock can be avoided, and drivability is improved.

If it is determined in step S2 that the combustion is uniform, the process proceeds to step S4, where the flow path switching valve 14
Is turned off to exit the routine.

Then, as shown in FIG. 2, the flow path switching valve 14 shuts off the bypass passage 13 and guides the intake air toward the intercooler 12. As a result, the air having a reduced intake air temperature is supplied to the combustion chamber 1a by the intercooler 12, and accordingly, the charging efficiency is increased and a high output is obtained.

FIG. 6 shows a second embodiment of the present invention. In the present embodiment, the intake air is to be supplied to the combustion chamber 1a through the bypass passage 13 even during the warm-up operation. That is, in step S1, the engine operating state is detected, and then in step S11, the cooling water temperature sensor 24
Is compared with the warm-up completion temperature Two. If the warm-up operation of Tw ≧ Two is completed, the process proceeds to step S2 to determine the combustion mode.
When the warm-up operation of Tw <Two is being performed, step S3
Proceed to.

Therefore, in this embodiment, during the warm-up operation,
Alternatively, when the combustion mode after the completion of the warm-up operation is uniform combustion, the flow path switching valve 14 is turned ON to supply the intake air to the combustion chamber 1a through the bypass passage 13. As a result, the intake air temperature during the warm-up operation is not reduced by the intercooler 12, and the operable region by the stratified combustion during the warm-up operation is expanded, so that not only the fuel efficiency can be improved, but also the warm-up can be improved. Shortening of machine time can be promoted.

The present invention is not limited to the above-described embodiment. For example, the combustion mode is changed to the high-pressure injector 15.
May be determined by the fuel injection pulse width with respect to. Further, whether or not the engine is being warmed up may be determined based on oil temperature, exhaust temperature, or the like in addition to the cooling water temperature.

[0026]

As described above, according to the present invention,
Since the intake air at the time of stratified combustion can be supplied without passing through the intercooler, the intake air temperature at the time of stratified combustion is not reduced, and good combustion can be obtained. The possible region is widened, and not only the fuel efficiency is improved, but also the combustion improvement rate can be further increased, and the exhaust emission and the torque shock are reduced, and the drivability is improved.

Further, by supplying the intake air without passing through the intercooler even during the warm-up operation, it is possible to widen the operating range due to the stratified combustion during the warm-up operation, thereby improving the fuel efficiency and improving the warm-up. Shortening of machine time can be promoted.

[Brief description of the drawings]

FIG. 1 is an overall schematic diagram of a direct injection engine with a supercharger during stratified combustion according to a first embodiment.

FIG. 2 is an overall schematic diagram of a direct injection engine with a supercharger during uniform combustion.

FIG. 3 is an enlarged view of the same combustion chamber.

FIG. 4 is a configuration diagram of the control device.

FIG. 5 is a flowchart showing a flow path switching control routine.

FIG. 6 is a flowchart showing a flow path switching control routine according to a second embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... In-cylinder injection engine 1a ... Combustion chamber 4 ... Intake passage 6 ... Supercharger (turbocharger) 12 ... Intercooler 13 ... Bypass passage 14 ... Flow switching valve 15 ... Injector

Claims (2)

[Claims] 1. An in-cylinder injection engine with a supercharger having a supercharger and an intercooler in an intake passage and an injector directly facing a combustion chamber, wherein an upstream and a downstream of the intercooler are provided in the intake passage. And a flow path switching valve that guides intake air to the bypass passage when the combustion mode is stratified combustion and guides the intake air toward the intercooler when uniform combustion is performed. An intake air temperature control device for a direct injection engine with a supercharger. 2. An in-cylinder injection engine with a supercharger having a supercharger and an intercooler in an intake passage and an injector directly facing a combustion chamber, wherein an upstream and a downstream of the intercooler are provided in the intake passage. When the combustion mode is stratified combustion and the warm-up operation has been completed, the intake air is guided to the bypass passage. During uniform combustion or during the warm-up operation, the intake air And a flow path switching valve for guiding the pressure in the direction of the intercooler.