JPH055432A - Intake and exhaust structure for engine - Google Patents

Abstract

PURPOSE:To contrive compatibility with fuel consumption while eliminating deterioration of an emission property due to decrease of exhaust gas temperature according to stratified combustion for improving the fuel consumption. CONSTITUTION:An engine having a plurality of cylinders is constituted by providing a fuel supply device 20 for stopping supply of fuel to some cylinders to cease combustion therein in a light load region of predetermined load or less and a communication path 42 for introducing intake air of increasing a pressure from a compressed combustion chamber 17 of the ceased cylinder into an intake combustion chamber 17 of the operating cylinder.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake / exhaust structure for an engine, which improves fuel efficiency while ensuring exhaust purification performance.

[0002]

2. Description of the Related Art A lean air-fuel ratio is effective in improving the fuel efficiency of an engine. For this reason, uneven distribution of fuel in the combustion chamber to carry out stratified combustion has been described, for example, It is publicly known as seen in Japanese Laid-Open Patent Publication No. 56534. In the fuel stratification in this prior art example, a fuel injection valve for directly supplying the fuel to the compression combustion chamber is arranged, and the fuel is unevenly distributed in the vicinity of the spark plug to secure good ignitability while maintaining the air-fuel ratio as a whole. It aims to achieve leanness.

[0003]

However, the above-described stratified combustion technique has the following problem of emission characteristics, and it is difficult to obtain a significant improvement in fuel efficiency.

That is, first, since the air-fuel mixture goes out of the stoichiometric air-fuel ratio region as the air-fuel ratio becomes leaner, the conventional three-way catalyst cannot be used, and excellent NOx purification can be performed even under lean conditions. NOx unless a high-performance catalyst is put to practical use
However, the amount of NOx generated must be suppressed by engine combustion, because the purification is insufficient and the amount of emission increases. Secondly, in order to significantly improve the fuel efficiency, it is necessary to make it extremely lean, but with this leaning, the exhaust gas temperature drops extremely, and the catalyst reaches the activation temperature for carrying out the oxidation reaction. As a result, unburned components cannot be sufficiently purified.

In order to solve the above problems, the intake closing timing is delayed to lower the pressure and temperature of the combustion chamber at the compression top dead center to suppress combustion and reduce the amount of NOx produced. It is possible to raise the exhaust gas temperature by promoting combustion, or raise the exhaust gas temperature by restricting the intake air to suppress the air filling amount in the combustion chamber. However, with the improvement of the emission performance by these methods, the combustion deteriorates from the idle region to the light load region where the most improvement in fuel efficiency performance is expected, so it is necessary to increase the fuel amount to ensure smooth drivability. There is a problem that improvement in fuel efficiency is insufficient.

In view of the above circumstances, therefore, the present invention reduces the generation of NOx without causing deterioration of combustion and raises the temperature of exhaust gas to improve the fuel efficiency significantly by stratified combustion. It is intended to provide an exhaust structure.

[0007]

In order to achieve the above object, an engine intake / exhaust structure of the present invention is an engine having a plurality of cylinders, and supplies fuel to some cylinders in a light load region of a predetermined load or less. And a communication passage for introducing intake air whose pressure has increased from the compression combustion chamber of the idle cylinder into the intake combustion chamber of the operating cylinder.

Further, it is preferable to install a one-way valve that opens at a predetermined pressure difference or more in the communication passage, and further install a fuel injection valve that directly injects fuel into the combustion chamber of each cylinder.

[0009]

In the intake / exhaust structure of the engine as described above, in the light load region, some cylinders are set as idle cylinders in which fuel supply is stopped by the fuel supply device to obtain a predetermined output by other operating cylinders. The fuel efficiency is improved by improving the combustion efficiency to obtain the same output, and the intake air whose pressure and temperature have been increased by adiabatic compression in the compression combustion chamber of the idle cylinder is introduced into the intake air of the operating cylinder through the communication passage. By pumping to the combustion chamber, this rise in intake air temperature raises the combustion temperature and improves the combustibility, as well as the exhaust gas temperature, which increases the catalyst temperature and enhances the purification performance by activation. As a result, it becomes possible to make lean by stratified combustion in the operating cylinder, and it is possible to improve fuel efficiency while ensuring emission characteristics through good purification of NOx, HC, CO, etc. Than it is.

If a one-way valve that opens at a predetermined pressure difference or more is installed in the communication passage, intake air with an increased pressure can be reliably pumped, and further, fuel injection for injecting fuel directly into the combustion chamber of each cylinder is possible. If a valve is installed, stratified charge combustion can be easily performed due to uneven distribution of fuel.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 and FIG. 2 show a structure including an intake / exhaust structure of an embodiment 2
Fig. 1 shows the overall structure of a cylinder rotary piston engine.
Then, the two cylinders are shown expanded to the left and right.

The casing of the rotary piston engine E includes rotor housings 11 and 11 whose inner peripheral surfaces are formed in a trochoid shape and are arranged in parallel, and side housings 12 and 11 located on both sides of the rotor housings 11 and 11, respectively. 12 and an intermediate intermediate housing 13, which are used as a first cylinder A (operating cylinder described later) and a second cylinder B.
(The same idle cylinder) is formed. Each of these cylinders A,
The space in B accommodates substantially triangular rotors 15 and 15, respectively, and each rotor 15 is supported by an eccentric shaft 16 so as to make a planetary rotational movement. And this each rotor 15
As a result, the space inside each cylinder A, B has three combustion chambers.
It is divided into 17 (working chambers), and the intake, compression, explosion, and exhaust strokes are performed as the rotor 15 rotates. The rotor 15 is linked so that an internal gear formed on the inner periphery of one side surface meshes with an external gear fixed to the side housings 12 at both ends so as to make a planetary rotational movement with a predetermined phase difference (180 °). There is.

Although not shown in detail, in order to seal between the combustion chambers 17, the rotor 15 has apex seals abutting against the inner peripheral surface of the rotor housing at the tops of the rotors 15 on both sides. Side seals are attached in an arc shape connecting the tops along the top, corner seals are attached to both sides of each top, and oil seals are attached to the inner peripheral side surface.

The side housing 12 or the intermediate housing 13 is formed with an intake port 21 which opens into the combustion chamber 17 at a position where an intake stroke is to be performed for each cylinder A, B. Independent intake passages 22a and 22b are respectively connected to the intake ports 21 of the cylinders A and B, the independent intake passages 22a and 22b on both sides are gathered in the surge tank 23, and the main throttle valve is provided in the upstream gathered intake passage 22.
An air flow sensor 26 for detecting the amount of intake air is provided in the intake passage 22 further upstream. Manifold injection valves 27a and 27b are provided in the independent intake passages 22a and 22b for the cylinders on both sides, and
An intake cut valve 29 for opening / closing the independent intake passage 22a for the first cylinder A (operating cylinder) is provided downstream of the manifold injection valve 27a.

Also, the rotor housing 11 of each cylinder A, B
An exhaust port 31 that opens into the combustion chamber 17 is formed at a position where an exhaust stroke should be performed, and an ignition plug 32 is disposed at a position where an explosion stroke should be performed. Further, first and second in-cylinder high pressure injection valves 33a and 33b are installed adjacent to the respective ignition plugs 32 of the first and second cylinders A and B, and the combustion chamber 17 is provided by these in-cylinder high pressure injection valves 33a and 33b. Fuel is directly injected and supplied to. Exhaust port 31 of each cylinder A, B
The exhaust passages 35 are connected to the exhaust passages 35 on both sides.
Are assembled on the downstream side, and the catalyst device 36 is interposed in this assembled portion. Further, an exhaust cut valve 37 is provided in the exhaust port 31 (or the exhaust passage 35) of the second cylinder B (rest cylinder). The first and second cylinders A and B
A fuel passage from a high-pressure fuel injection pump 38 is connected to each in-cylinder high-pressure injection valve 33a, 33b, and pressurized fuel is supplied.

On the other hand, on the inner surface of the intermediate housing 13 (or side housing 12) on the side of the first cylinder A, an auxiliary intake port 40 communicating with the combustion chamber 17 in the intake stroke near the intake port 21 is provided. On the inner side surface of the intermediate housing 13 (which may be the side housing 12) on the second cylinder B side, which is opened, air is communicated with the combustion chamber 17 in the vicinity of the intake port 21 from the intake stroke to the compression stroke. Port 41 is open. And the auxiliary intake port
40 and the air supply port 41 are communicated with each other by a communication passage 42, and the one-way opening operation is performed in the communication passage 42 when the pressure on the air supply port 41 side becomes higher than a pressure on the auxiliary intake port 40 side by a predetermined value or more. A valve 43 is provided, and an air supply cut valve 44 that opens and closes the communication passage 42 is provided on the auxiliary intake port 40 side of the one-way valve 43. The communication passage 42 is
As shown in FIG. 2, it is formed through the inside of the intermediate housing 13.

Both of the manifold injection valves 27a and 27b, the first
Further, the fuel supply device 20 including the second in-cylinder high pressure injection valves 33a and 33b and the high pressure fuel injection pump 38 and performing the fuel injection control has the first load in the light load region where the engine load is equal to or lower than a predetermined value.
Fuel injection is performed only by the in-cylinder high-pressure injection valve 33a, fuel injection by the other injection valves 27a, 27b, 33b is stopped to cut off fuel supply to the second cylinder B, and the second cylinder B is deactivated. 1
The operation is performed only by the cylinder A. A part of the fuel supply control by the fuel supply device 20 is constituted by a controller 50 that controls the entire engine.

A throttle motor 51 is connected to the main throttle valve 25, and is opened / closed to a predetermined throttle opening by the operation of the throttle motor 51. Further, the intake cut valve 29, the exhaust cut valve 37, and the air cut valve 44 have actuators 52, 5 respectively.
3, 54 are installed, and the cut valves 29, 37, 44 are opened and closed by operating the actuators 52 to 54. Then, the throttle motor 51, each cut valve 29, 37, 44
For the actuators 52 to 54 of
A control signal is output from 50, and its operation is controlled according to the operating state.

The controller 50 includes an intake air amount signal from the air flow sensor 26, an accelerator opening signal from an accelerator sensor 55 for detecting an accelerator operation amount (engine load), and an engine rotation speed in order to detect an operating state. A rotation speed signal or the like is input from a rotation sensor 56 that detects the number of rotations.

The intake and fuel control by the controller 50 will be described with reference to the flowchart of FIG. After the control is started, detection signals from various sensors are read in step S1, and it is determined in step S2 whether or not the current operating state is in the light load region. For example, as shown in FIG. 3, this control map is set by the engine speed and the accelerator opening degree, the operating state of the low accelerator opening degree and the low rotation speed area is set to the light load area L, and other than that is set. It is set to the medium / high load region H.

If the determination in step S2 is YES and the vehicle is in the light load region L, the process proceeds to step S3 to open the main throttle valve 25 to the fully open state, and at step S4, the intake cut valve 29 and the exhaust cut valve are opened. While closing 37, the air cut valve 44 is opened in step S5. Further, in step S6, the fuel injection by the in-cylinder high pressure injection valve 33b to the second cylinder B is stopped, and
The fuel injection by the manifold injection valves 27a, 27b for both cylinders A, B is stopped.

Then, in step S7, various corrections are made to the basic injection amount based on the accelerator opening to calculate the fuel injection amount, and in step S8 a signal corresponding to this fuel injection amount is output to the high pressure fuel injection pump 38. , The fuel is injected into the first cylinder A by the first in-cylinder high-pressure injection valve 33a, and the load is controlled by this injection amount.

On the other hand, if the determination in step S2 is NO and the vehicle is in the medium / high load region H, the process proceeds to step S9 to calculate the opening of the main throttle valve 25 based on the accelerator opening. The load is controlled in degrees. Then, in step S10, a control signal corresponding to the throttle opening is output to the throttle motor 51 to drive the main throttle valve 25. Further, the intake cut valve 29 and the exhaust cut valve 37 are opened in step S11, while the air supply cut valve 44 is closed in step S12.

Regarding fuel injection, firstly in step S13
While the fuel injection by the first and second in-cylinder high pressure injection valves 33a, 33b to the second cylinders A, B is fixed to a predetermined value, the intake air amount and the basic injection amount based on the engine speed are set in step S14. The fuel injection amount is calculated by performing various corrections, and a signal corresponding to this fuel injection amount is output in step S15 to the manifold injection valves for the first and second cylinders A and B.
27a, 27b to supply fuel to both cylinders from the intake passages 22a, 22b.

Explaining the operation of the above-mentioned processing, when in the light load region L, the first cylinder A is the operating cylinder and the second cylinder B is the idle cylinder. That is, first, in the light load region L, the intake cut valve 29 is closed and the air feed cut valve 44 is opened. Therefore, the intake air passes through the fully open main throttle valve 25 and from the independent intake passage 22b for the second cylinder B. When it flows into the intake combustion chamber 17 of the second cylinder B through the intake port 21, this combustion chamber 17 shifts to the compression stroke, the pressure due to compression in the latter period rises, and the one-way valve 43 opens, The intake air, which has been adiabatically compressed and whose pressure and temperature have risen, is pressure-fed to the intake combustion chamber 17 of the first cylinder A through the communication passage 42.

The in-cylinder high pressure injection valve 33 of the first cylinder A is also used.
By a, fuel corresponding to the load is injected so as to be unevenly distributed in the vicinity of the spark plug 32, and stratified charge combustion is performed. The exhaust gas after combustion is discharged from the exhaust port 31 to the exhaust passage 35,
After being purified by the catalyst device 36, it is released into the atmosphere. that time,
Since the exhaust cut valve 37 is closed, the first cylinder A
Exhaust gas from the second cylinder B where the pressure is not high in the idle cylinder
From flowing into the combustion chamber 17 from the exhaust port 31 of the second cylinder B, and preventing the air remaining in the combustion chamber 17 in the posture of the exhaust stroke of the second cylinder B from being discharged to the exhaust passage 35. ..

In the light load operation as described above, the intake air whose temperature has risen due to adiabatic compression in the second cylinder B from the auxiliary intake port 40 flows into the first cylinder A, which is the operating cylinder. , The combustion temperature in stratified combustion becomes higher,
The exhaust gas whose temperature has risen flows into the catalyst device 36 from the exhaust port 31 and raises the catalyst temperature to fully activate the NO gas.
Performs good purification of x, HC, CO, etc. In addition, as the number of operating cylinders is reduced, when operating with both cylinders, the amount of heat generated is small and the exhaust gas temperature decreases with the supply of a small amount of fuel to each cylinder. The amount of fuel supplied to the first cylinder A in order to obtain it in the cylinder is large, and the exhaust gas temperature becomes high.

Further, since the main throttle valve 25 is fully opened and the load control is performed by the injection amount of the first in-cylinder high pressure injection valve 33a, the pumping loss is reduced and the fuel consumption performance is further enhanced in addition to the lean combustion by stratified combustion. Become.

On the other hand, in the medium to high load operation, the required output is ensured by operating with both cylinders A and B. That is, the intake air that has flowed in through the main throttle valve 25 that is opened to the degree of opening corresponding to the load is opened from the intake cut valve 29, and therefore, from the independent intake passages 22a, 22b on both sides through the intake port 21 and each cylinder. The air flows into the intake combustion chambers 17 of A and B, and the air cut valve 44 is closed so that there is no flow of intake air through the communication passage 42, and the intake air is compressed and explosively exhausted in each cylinder. Then, the fuel is mainly supplied by the manifold injection valves 27a, 27b, and is mixed with the intake air in the intake passage in advance to promote vaporization and atomization to obtain good combustibility, and the in-cylinder high pressure injection valves 33a, 33b. In this way, a predetermined amount of fuel is injected, and operation reliability is obtained by cooling the injection valve and preventing clogging. Also, exhaust cut valve
37 is opened, the exhaust gas burned in each cylinder is discharged to the exhaust passage 35, and is purified by the catalyst device 36.

According to the above-described embodiment, it is possible to maintain the good purification performance of the catalyst device 36 by raising the intake air temperature and the exhaust gas temperature by the pre-stage compression of the intake air and to secure the emission performance. At the same time, it is possible to achieve compatibility with fuel efficiency by implementing stratified combustion.

Although the example of the rotary piston engine has been described in the above embodiments, the present invention can be applied to other multi-cylinder engines.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a two-cylinder rotary piston engine having an intake / exhaust structure according to an embodiment of the present invention.

FIG. 2 is a schematic vertical sectional view of the engine.

FIG. 3 is a map diagram showing a setting example of a control area.

FIG. 4 is a flow chart diagram for explaining processing of a controller.

[Explanation of symbols]

 E engine A operating cylinder B idle cylinder 17 combustion chamber (working chamber) 20 fuel supply device 21 intake port 22 intake passage 27a, 27b manifold injection valve 29 intake cut valve 33a, 33b in-cylinder high pressure injection valve 35 exhaust passage 36 catalyst device 37 Exhaust cut valve 40 Auxiliary intake port 41 Air supply port 42 Communication passage 43 One-way valve 44 Air supply cut valve 50 Controller

Claims (1)

Claim: What is claimed is: 1. An engine having a plurality of cylinders,
A fuel supply device that stops the supply of fuel to some cylinders in the light load region of a predetermined load or less to stop combustion in the cylinders, and a cylinder that operates intake air with increased pressure from the compression combustion chamber of the idle cylinder. An intake and exhaust structure for an engine, comprising: a communication passage that is introduced into the intake and combustion chamber of the engine. 2. The intake / exhaust structure for an engine according to claim 1, wherein the communication passage includes a one-way valve that opens at a predetermined pressure difference or more. 3. The intake / exhaust structure for an engine according to claim 1, wherein the fuel supply device includes a fuel injection valve for directly injecting fuel into the combustion chamber of each cylinder.