JPH05321706A - Control device of two cycle engine - Google Patents

Abstract

PURPOSE:To transfer operating condition to load operation smoothly while ensuring stable combustion under a proper air fuel ratio by operating firstly a part of cylinder in all cylinders when CONSTITUTION:In an engine 1, a supercharger 12 is arranged on an intake passage 8, and an inter cooler 13 and a throttle valve 14 are arranged in order on the downstream side thereof. A bypass valve 17 for regulating the return amount of supercharging air is arranged in a return passage 16 for returning remaining supercharging air to the upstream side of the supercharger 12. The throttle valve 14 and the bypass valve 17 are driving controlled by a controller 23 through each actuator 28, 29 on the basis of detecting signals of various kinds of sensors 25 to 30 for detecting operating condition of the engine 1 respectively. In the abovementional constitution, firstly, only a part of cylinder is operated when starting of the engine 1 is detected, in the controller 23. The number of cylinder for operating next is increased, stepwise up until total number of cylinders.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control system for a V-type two-cycle engine, and more particularly, to a multi-cylinder two-cycle engine which controls the number of cylinders at engine start.
The present invention relates to a control device for a cycle engine.

[0002]

2. Description of the Related Art Conventionally, various types of two-cycle engines have been proposed (for example, JP-A-59-4931).
6, JP-A-59-79040, JP-A-62-113.
820, JP-A-63-248915, JP-A-64-
63617, JP-A-62-135655, etc.).

In such a two-cycle engine, the cylinder before starting the engine is generally substantially occupied by fresh air. When the engine is started, a small amount of fuel is injected into the cylinder and ignited, and subsequently the engine is operated under no load at a low boost pressure and a high dilution rate.

[0004]

However, if fuel is injected into a cylinder that has no residual combustion gas and is completely occupied by fresh air, lean combustion or lean combustion is not possible unless ideal fuel stratification is achieved. Due to non-uniform mixing of fuel and air, misfire and high torque shock are likely to occur.

The present invention has been made in view of the above circumstances, and provides a two-cycle engine capable of smoothly shifting to load operation while ensuring stable combustion under an appropriate air-fuel ratio when the engine is started. The purpose is to provide a control device.

[0006]

In order to solve the above-mentioned problems, the present invention is constructed as follows. That is, the engine according to the present invention is a multi-cylinder two-cycle engine, and the control device includes a start detection means for detecting the start of the engine and only a part of all cylinders receiving the output of the start detection means. And a second operating means for gradually increasing the number of operating cylinders to the total number of cylinders after operating some of the cylinders by the first operating means.

According to the above configuration of the present invention, the first operating means operates only some of the cylinders immediately after the engine is started, and the second operating means gradually increases the number of operating cylinders. Finally, activate all cylinders. Therefore, immediately after the engine is started, only some of the cylinders operate at a relatively high load,
The engine produces a lower torque than if all cylinders were operating in unison. Then, all the cylinders are operated with a slight delay after the operation of some of the cylinders, and the engine shifts to the load operation. Under such control of the number of cylinders, an appropriate air-fuel ratio of each cylinder can be secured and a sudden increase in engine rotation can be avoided.

In a preferred embodiment of the present invention, the engine includes a supercharger for performing intake supercharging and pressure control means for controlling supercharging pressure by the supercharger, and only some cylinders are in operation. The supercharging pressure during the operation is set to be relatively higher than that when all the cylinders are operating. With this configuration, it is possible to smoothly increase the rotation of the engine while suppressing an increase in the rotation of the engine caused by the increase in the number of operating cylinders.

In another preferred embodiment of the present invention, an exhaust gas recirculation device for recirculating exhaust gas and an exhaust gas recirculation control means for activating the exhaust gas recirculation device at engine startup are provided. According to this configuration, the fresh air in the cylinder that is in the non-operating state is partially replaced with the exhaust gas before operating. Therefore, the engine does not cause a sudden torque increase during the operation of such cylinders.

In a further preferred embodiment of the invention, the cylinder number control and / or exhaust gas recirculation described above is prohibited if the engine has been off for a relatively short period of time.
That is, in general, when the so-called engine is restarted, the burned gas still remains in each cylinder. Therefore, if unreasonable cylinder number control or excessive EGR is performed, so-called engine stall may occur. All cylinders are operated promptly without control, and responsiveness at restart is secured.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of a two-cycle engine to which the present invention is applied, and FIG. 2 is a vertical sectional view showing the structure of the engine shown in FIG. The engine 1 of this example is configured as a V-type 4-cylinder two-cycle engine having a so-called uniflow type scavenging structure. A cylinder bore 2 is formed in each of the left and right banks. In the bank on the left side in FIG. 2, the first and third banks are provided.
The cylinders are provided, and the banks located on the right side of FIG. 2 are provided with the second and fourth cylinders. The ignition order of the engine 1 is set in the order of the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder. A piston 3 is slidably arranged in each cylinder bore 2. The piston 3 is connected via a connecting rod 4 to a crankshaft 6 in a crank chamber 5 that takes out combustion energy as rotational power.

The upper space defined by the upper portion of the cylinder bore 2 and the upper surface of the piston 3 constitutes a combustion chamber 7. The cylinder wall 11 (FIG. 2) that defines the cylinder bore 2 is provided with a large number of scavenging ports 9 that are circumferentially spaced from each other. The scavenging port 9 is arranged so that the intake air is introduced into the combustion chamber 7 almost uniformly over the entire circumference of the cylinder bore 2. An intake passage 8 is formed around the scavenging port 9, and the intake passage 8 communicates with the combustion chamber 7 via the scavenging port 9.

At the tip of the intake passage 8, that is, at the most upstream side,
An air cleaner 10 is arranged, and an air flow meter 11 that detects an intake air amount is provided downstream of the air cleaner 10.
The supercharger 12 that supercharges the intake air is the air flow meter 11
An intercooler 13 that cools the supercharged air is provided downstream of the supercharger 12. A throttle valve 14 is provided downstream of the intercooler 13,
An intake chamber 15 is provided further downstream, and thus an intake system of the engine 1 is configured. Further, in the configuration of this example, the return passage 16 for returning the excess supercharged air to the upstream side of the supercharger 12 is provided. The take-out portion of the return passage 16 includes an intercooler 13 and a throttle valve 14.
It is provided in the area between and. The return passage 16 is provided with a bypass valve 17 for adjusting the return amount of supercharged air.

An exhaust passage 18 is connected to the upper portion of the combustion chamber 7, and an exhaust valve 20 is attached to the opening, that is, the exhaust port 19. The engine 1 of this example is of a cylinder injection type, and an injector 21 for injecting fuel is attached near the exhaust passage 18. Further, a spark plug 22 is attached to the upper part of the combustion chamber 7. The upstream end of the EGR (exhaust gas recirculation) passage 40 is connected to the exhaust passage 18. The EGR passage 40 has an EGR passage provided at its downstream end.
It is connected to the intake chamber 15 via a valve 41.

Above the scavenging port 7, there is a cylinder bore 2
A cooling water passage 31 is arranged so as to surround the entire circumference of the exhaust gas, and an exhaust passage 18 is connected to the upper portion of the combustion chamber 7.
As shown in FIG. 2, the engine 1 includes a horizontal partition plate 32 that defines the upper end of the intake chamber 15, and the partition plate 32 is disposed so as to bridge the left and right cooling water passages 31. .. The intake chamber 15 includes a main passage 15a having a V-shaped cross section, which is formed by the partition plate 32 and inner walls of both banks.
It is composed of an extension passage 15b extending from the main passage 11a to the outer periphery of the cylinder bore 2. The extension passage 15b extends along the outer periphery of the cylinder wall 11, and all the scavenging ports 9 communicate with the main passage 15a or the extension passage 15b.

The partition plate 32 is connected to the downstream end of the EGR passage 40 (shown in phantom line) via the EGR valve 41 (shown in phantom line). Further, above the partition plate 32, the supercharger 1
2 is arranged, the discharge port of the supercharger 12 is connected to the intercooler 13 (FIG. 1) via the pipe 8a, and the intercooler 13 is connected to the intake chamber 15 as shown in FIG.

As shown in FIG. 1, in order to control the engine 1, a controller 23 preferably including a microcomputer is provided. The controller 23 includes a distributor 24 and a throttle valve 1
4, an intake pressure sensor 25 that detects the pressure in the intake passage 8, an accelerator position sensor 27 that detects the depression amount of the accelerator pedal 26, a crank angle sensor 28 that detects the crank angle of the crankshaft 5, and a cooling water temperature. Each detection result from the water temperature sensor 43 for detection is input.

The controller 23 performs a predetermined calculation based on the detection results of these sensors to output a throttle opening signal to the actuator 28 of the throttle valve 14 and a bypass opening signal to the actuator 29 of the bypass valve 17. Is output to control the opening of the throttle valve 14 and the opening of the bypass valve 17. As a result, the boost pressure downstream of the throttle valve 14, that is, the intake pressure is controlled. Further, the controller 23 controls the number of operating cylinders, the intake pressure, and the EGR amount when the engine is started.

FIG. 3 is a flow chart showing an operation control routine for starting the engine, which is executed by the controller. When the starter signal is input and the controller 23 is instructed to start the engine 1 (S1), the controller 23 executes the illustrated control routine. The controller 23 first reads the cooling water temperature from the detection result of the water temperature sensor 43 (S2), and when the cooling water temperature Tw is lower than the predetermined cooling water temperature Tw1, sets the supercharging pressure and sets the target value of the idle speed. R is set (S3 to S5). Controller 2
3 is the only cylinder among the four cylinders (first cylinder in this example).
(Cylinder) is supplied with fuel, and only this cylinder, that is, the first cylinder is operated (S6). Therefore, the other cylinders are not supplied with fuel and do not operate. Thus, engine 1
Is started by operating only the first cylinder.

The controller 23 also opens the EGR valve 41 to recirculate the exhaust gas to the intake chamber 15. Therefore, exhaust gas is introduced into the other three cylinders that are not operating,
The proportion of fresh air in these cylinders is reduced. If the engine speed is higher than the target value R, the controller 23 further reduces the boost pressure (S8, S9). The supercharging pressure can be reduced by monitoring the intake pressure detected by the intake pressure sensor 25 and activating the actuator 29 of the bypass valve 17.
The bypass opening signal is output to increase the opening degree of the bypass valve 17. In this case, the opening of the throttle valve 14 may be reduced in order to reduce the boost pressure.

When the engine speed is equal to or lower than the target value R, the controller 23 reduces the supercharging pressure and increases the number of operating cylinders by one, and the engine 1 operates by operating two cylinders ( S10). The second cylinder to be operated is set to the third cylinder in order to make the combustion intervals even. The controller 23 reduces the boost pressure when the engine speed is higher than the target value R (S1).
1, S12). As described above, the supercharging pressure is reduced by controlling the opening degree of the bypass valve 17 or the opening degree of the throttle valve 14.

After that, like the second cylinder, one of the other two cylinders, for example, the second cylinder is operated, and then the last cylinder, for example, the fourth cylinder is operated. Thus, when all the cylinders are in operation (S13), the controller 23
Closes the EGR valve 41 and ends the exhaust gas recirculation operation mode (S14). At this point, if the engine speed is higher than the target value R, the boost pressure is reduced by the above method (S
15, 16), on the other hand, the engine speed R is the target value R
If it is below, the boost pressure is increased until the engine speed reaches the target value R (S17, S18).

The change in the amount of fresh air in the cylinder at the time of engine start obtained by such control is illustrated in the time chart of FIG. As shown in FIG. 4, the total amount V of fresh air in all the cylinders when only one cylinder is operated is halved when two cylinders are operated, and as three cylinders and all cylinders are sequentially operated. , Gradually decrease.
In the time chart of FIG. 4, for convenience of drawing, EG
The R amount is ignored.

The case where the cooling water temperature Tw is lower than the predetermined cooling water temperature Tw1, that is, the case where the engine 1 is considered to have been stopped for a relatively long period of time has been described above. If it can be determined that the engine 1 is stopped for a relatively short period of time in the temperature range equal to or higher than the water temperature Tw1, the controller 2
No. 3 emphasizes the responsiveness at the time of starting the engine 1, and does not perform the above-described operating cylinder number control. That is, the controller 23
Sets the supercharging pressure, sets the target value R of the idle speed (S20, S21), and operates all the first to fourth cylinders (S22).

In this way, the engine 1 of this embodiment has four
It is a cylinder two-cycle engine, and when the engine starts,
The controller 23 is configured to gradually increase the number of operating cylinders to a total number of cylinders after operating only some of the cylinders. Controller 23
Since only one cylinder is operated first when the engine is started, the engine 1 produces a lower torque than in the case where all the cylinders are operated simultaneously. Then the controller 2
In No. 3, the other three cylinders are sequentially operated to gradually shift the engine to the load operation.

Under the control of the number of cylinders, an appropriate air-fuel ratio of each cylinder can be secured and a sudden increase in engine rotation can be avoided. Further, the engine 1 includes a supercharger 12 that performs intake supercharging, and a bypass valve 17 or a throttle valve 14 that controls supercharging pressure by the supercharger 12, and the controller 23 operates only some cylinders. During this period, the supercharging pressure of the intake system is set relatively higher than when all cylinders are operating. Therefore, it is possible to smoothly increase the rotation of the engine while suppressing the increase of the rotation of the engine caused by the increase in the number of operating cylinders.

[0027]

According to the above configuration of the present invention, it is possible to provide a control system for a two-cycle engine that can smoothly shift the engine to a load operation while ensuring stable combustion under an appropriate air-fuel ratio at the time of engine startup. It will be possible.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a two-cycle engine to which the present invention is applied.

FIG. 2 is a vertical cross-sectional view showing the structure of the engine shown in FIG.

FIG. 3 is a flowchart showing an operation control routine at engine start.

FIG. 4 is a time chart showing changes in the fresh air amount in the cylinder when the engine is started.

[Explanation of symbols]

 1 Engine 2 Cylinder Bore 3 Piston 4 Connecting Rod 5 Crank Chamber 6 Crank Shaft 7 Combustion Chamber 8 Intake Passage 9 Scavenging Port 10 Air Cleaner 11 Air Flow Meter 12 Supercharger 13 Intercooler 14 Throttle Valve 15 Surge Tank 16 Return Passage 17 Bypass Valve 18 Exhaust Passage 19 Exhaust port 20 Exhaust valve 21 Injector 22 Spark plug 23 Controller 24 Distributor 25 Intake pressure sensor 26 Accelerator pedal 27 Accelerator position sensor 28 Throttle actuator 29 Bypass valve actuator 30 Crank angle sensor 31 Cooling water passage 32 Partition plate 40 EGR passage 41 EGR Valve 43 Water temperature sensor

Claims (4)

[Claims] 1. A start detecting means for detecting the start of an engine, a first operating means for receiving only the output of the start detecting means and operating only some of the cylinders, and the first operating means. And a second operating means for gradually increasing the number of operating cylinders up to the total number of cylinders after operating some of the cylinders. 2. The engine comprises a supercharger for performing intake air supercharging, and pressure control means for controlling supercharging pressure by the supercharger, wherein the pressure control means operates only some of the cylinders. 2. The control device for a two-cycle engine according to claim 1, wherein the supercharging pressure during the operation is set relatively higher than that when all the cylinders are operating. 3. An exhaust gas recirculation device for recirculating exhaust gas,
The control system for a two-cycle engine according to claim 1 or 2, further comprising: an exhaust gas recirculation control unit that operates the exhaust gas recirculation device when the engine is started. 4. The engine starting after the operation of the exhaust gas recirculation device by the control of the number of cylinders and / or the exhaust gas recirculation control means at the time of starting by the first and second operating means is stopped for a relatively short period of time. The control device for a two-cycle engine according to any one of claims 1 to 3, wherein the control is prohibited in such a case.