JP3328747B2 - Engine control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine control device for applying an engine brake during deceleration.

[0002]

2. Description of the Related Art In general, when an engine is decelerated, the throttle valve is fully closed and an engine brake is applied by applying a load to a piston. In an engine having a large intake and exhaust overlap such as a two-cycle engine, the throttle valve is fully closed. The engine brake does not work because there is backflow from the exhaust system. Then, the actual opening 62-9513
In the two-stroke engine described in Japanese Patent Application Publication No. 5 (1990), the engine brake is activated by closing the on-off valve of the bypass passage that bypasses the mechanical supercharger during deceleration to increase the load on the mechanical supercharger. .

[0003]

As described above, when the on-off valve of the bypass passage that bypasses the mechanical supercharger is closed to apply the engine brake during deceleration, only air is introduced into the cylinder during deceleration. Since the gas flows into the exhaust system, the in-cylinder temperature and the catalyst temperature drop, which causes poor fuel vaporization and poor catalyst activity when switching to normal operation. Responsiveness is deteriorated. Further, when the on-off valve of the bypass passage is closed at the time of deceleration, the temperature of the mechanical supercharger sharply rises due to an increase in load, which causes a failure.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and in an engine having a large intake and exhaust overlap, responsiveness at the time of re-acceleration is maintained while maintaining the in-cylinder temperature and the catalyst temperature. An object of the present invention is to enable an engine brake to be effectively applied while suppressing a temperature rise of a mechanical supercharger.

[0005]

SUMMARY OF THE INVENTION The present invention comprises a plurality of exhaust ports of a valve opening / closing type, for example, in two cycles, and comprises a cylinder.
A swirl flow is generated in the exhaust port and the swirl flow is generated in the exhaust port.
In engine <br/> emissions control device that is intended to pass through the combustion chamber side opening lower surface of the bets, a deceleration detecting means for detecting a deceleration of the engine, receives the output of the deceleration detecting means, of the engine Of the exhaust valves that open and close the plurality of exhaust ports at the time of deceleration, the exhaust valve through the lower surface of the opening on the combustion chamber side through which swirl flows passes.
Exhaust valve operation control means for normally opening and closing only the exhaust valve having the smallest excess area and making it difficult for the swirl to flow out, and for closing the remaining exhaust valves in a closed state is provided. .

[0006] In the engine, when a swirl flow is generated in the cylinder and the swirl flow passes through the lower surface of the exhaust port on the combustion chamber side, the exhaust valve operation control means controls the swirl flow during deceleration. It is preferable to normally open and close the exhaust valve of the exhaust port having the smallest passage area on the lower surface of the opening on the combustion chamber side through which the flow passes.

[0007]

[Function] During deceleration, only one of the plurality of exhaust valves is opened and closed as usual, and the rest is stopped in a closed state, so that a portion of air is supplied to the exhaust system while obtaining sufficient engine brake. By allowing the gas to flow out, air is secured together with the residual gas in the cylinder, and an appropriate responsiveness at the time of reacceleration can be maintained. In addition, only the exhaust valve of the exhaust port where swirl is least likely to flow out during deceleration is normally opened and closed, and the remaining exhaust valves are stopped in the closed state, thereby promoting the above-described operation.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a system diagram of the first embodiment of the present invention. In the drawing, reference numeral 1 denotes a uniflow type two-cycle engine, in which a cylinder chamber 3 is provided inside a cylinder block 2.
Is formed, and the cylinder head 4 is connected to the upper part thereof. A combustion chamber recess 5 is formed on the inner surface of the cylinder head 4. FIG. 3 is an explanatory view of the shape of the combustion chamber recess 5 as viewed from the lower surface of the cylinder head 4.

An intake port 7 is formed at a lower portion of the cylinder block 2 so as to be opened and closed at a predetermined timing as the piston 6 moves up and down. On the other hand, the combustion chamber recess 5 of the cylinder head 4 has two exhaust ports 8a,
8b, and exhaust valves 9a and 9b for opening and closing the exhaust ports 8a and 8b. In addition, a fuel injection valve 10 and a spark plug 11 are provided in the combustion chamber recess 5.

The combustion chamber recess 5 has a substantially triangular shape as shown in FIG. 3, and the two exhaust ports 8a and 8b are provided at each corner on the bottom side. When these exhaust ports 8a and 8b are opened, swirl flows into the combustion chamber recess 5 as shown by arrows, and flows out from the exhaust ports 8a and 8b. At this time, the exhaust port 8a located on the upstream side of the swirl flow is located in the area a shaded in FIG. 3 in the range of the valve seat, and the exhaust port 8a is located on the downstream side of the swirl flow. 8b, the swirl flow is shaded in the area b shaded in FIG. 3 also in the range of the valve seat, but the downstream exhaust port 8b is in contrast to the area a in the swirl flow of the upstream exhaust port 8a. The area b behind the swirl flow is small, and therefore, the swirl flow is easier to flow out of the exhaust port 8b on the downstream side.

A surge tank 12 is formed in the cylinder block 2 upstream of the intake port 7. In the intake passage 13 connected to the inlet of the surge tank 12, a throttle valve 14, a mechanical supercharger 15, and an intercooler 16 are installed in order from the upstream. In addition, a bypass passage 17 that branches off from the intake passage 13 downstream of the throttle body 14 and bypasses the mechanical supercharger 15 and the intercooler 16 is provided, and a bypass control valve 18 is installed in the bypass passage 17.

The exhaust valves 9a and 9b are driven by a cam 20 interlocking with a crankshaft 19 of the engine 1 in synchronization with a crank angle. The drive system has a valve stop mechanism 2 that can stop the operation of the exhaust valve 9b on the downstream side of the swirl.
1 is provided. The engine 1 is equipped with a control unit 22 constituted by a microcomputer, and a crank angle sensor 23 for detecting the rotation angle of the crank shaft 19 as engine speed information.
And a throttle sensor 24 for detecting the opening of the throttle valve 14, and a boost sensor 25 for detecting a boost pressure upstream of the surge tank 12.

The exhaust ports 8a and 8b are opened at a predetermined crank angle in the latter half of the expansion stroke and closed at a predetermined crank angle in the early stage of the compression stroke. The intake port 7 is opened at a crank angle after a predetermined period of time after the exhaust port 8 is closed in the expansion stroke, and is closed at a crank angle after a predetermined period of time after the exhaust port 8 is closed in the compression stroke.

The control unit 22 receives an engine rotation signal from the crank angle sensor 23, a boost pressure signal from a boost sensor 25, and a throttle opening signal from a throttle sensor 24. The control unit 22 determines the fuel injection amount based on the engine speed and the boost pressure calculated from the output of the crank angle sensor 23, and outputs an injection signal for obtaining the fuel injection amount to the fuel injection valve 10. Is done. Further, the control unit 22 detects the deceleration of the engine when the condition that the engine speed is equal to or higher than the predetermined speed and the throttle valve opening is fully closed is satisfied.
At the time of deceleration, the fuel is cut, and the exhaust valve 9b on the downstream side of the swirl is stopped in a closed state by the control of the valve stop mechanism 21.

FIG. 4 is a flowchart for executing the control at the time of deceleration of the above embodiment. S1 to S6 indicate the respective steps.

In the flowchart of FIG. 4, when the process is started, the engine speed Ne, boost pressure and throttle valve opening TVO are read in S1. Then, in S2, it is determined whether or not the vehicle is decelerating based on the engine speed Ne and the throttle valve opening TVO.

When it is determined in S2 that the vehicle is decelerating,
Proceeding to S3, a fuel cut is performed, and in S4, the exhaust valve 9b on the downstream side of the swirl is stopped.

If it is determined in S2 that the vehicle is not decelerating, normal fuel injection is executed in S5, and both exhaust valves 9 are executed in S6.
a, 9b are operated.

Although the above embodiment has been described with reference to a uniflow type two-stroke engine in which only the exhaust port is a valve opening / closing type, the present invention relates to a loop scavenging type two-stroke engine in which both the intake port and the exhaust port are valve opening / closing types. The present invention can be applied to other engines such as a cycle engine and a four-cycle engine.

[0021]

As described above, the present invention is configured as described above.
The engine brake can be effectively applied while maintaining the in-cylinder temperature and the catalyst temperature during deceleration.In addition to ensuring responsiveness during re-acceleration after applying the engine brake, mechanical It is possible to prevent a failure from occurring due to a rise in the temperature of the turbocharger.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of the present invention.

FIG. 2 is a system diagram of an embodiment of the present invention.

FIG. 3 is an explanatory view of a shape of a recess of a combustion chamber according to one embodiment of the present invention.

FIG. 4 is a flowchart for executing control according to an embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Uniflow type two-stroke engine 7 Intake port 8a, 8b Exhaust port 9a, 9b Exhaust valve 21 Valve stop mechanism 22 Control unit 23 Crank angle sensor 24 Throttle sensor 25 Boost sensor

──────────────────────────────────────────────────続 き Continuing from the front page Examiner Daiki Inaba (56) References Japanese Utility Model Sho 59-184335 (JP, U) Japanese Utility Model Sho 63-243414 (JP, U) Japanese Utility Model Utility Model Hei 2-126033 (JP, U) ( 58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 13/00-28/00

Claims (2)

(57) [Claims] A plurality of valve opening / closing exhaust ports ;
A swirl flow is generated in the Linda, and the swirl flow is discharged.
An engine control device configured to pass through a lower surface of a combustion chamber-side opening of an air port , comprising: deceleration detecting means for detecting deceleration of the engine; Of the exhaust valves that open and close the plurality of exhaust ports during deceleration ,
The passage area of the lower surface of the opening on the combustion chamber side where the whirl flow passes
An engine control device comprising: an exhaust valve operation control means for normally opening and closing only an exhaust valve which is small and hardly causes a swirl to flow out , and stopping the remaining exhaust valves in a closed state. 2. The engine control device according to claim 1, wherein said engine is a two-stroke engine.