JP2000179322A - Crankcase emission control system for variable valve train engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ventilate crankcase ideally in a variable valve train engine that performs non-throttle operations. SOLUTION: Pipings 18, 20 are used to provide a dual circuit to connect, at respective different points, a portion in an engine body 1, at which blow-by gas stagnates, to an air intake passageway 12. One-way valves 19, 21 are placed in pipings 18, 20, respectively, in a direction opposite to each other. That is, a first piping 18, in which the one-way valve 19 that allows gas to flow in the direction toward the air intake passageway 12 is placed, is connected from part C in a crankcase of the engine body 1, at which there are large fluctuations in pressure caused by blow-by gas from a piston, to part A near an air intake valve with a large air intake pulsation in the air intake passageway 12. A second piping 20, in which the one-way valve 21 that allows gas to flow in the direction toward the engine body 1 is placed, is connected from part B near an air cleaner with a small air intake pulsation in the air intake passageway 12 to part D in a rocker cover of the engine body 1, at which there are small fluctuations in pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a blow-by gas reducing apparatus for a variable valve engine that controls the operation of an intake valve to control the amount of intake air.

[0002]

2. Description of the Related Art Heretofore, there has been a conventional one that drives an intake valve and an exhaust valve by using a variable valve operating device, for example, an electromagnetic drive device, and controls the opening and closing operations of these valves arbitrarily (JP-A-8-20).
0025).

Further, in recent years, in order to improve fuel efficiency by reducing pump loss, the operation of the intake valve is controlled, for example, the opening timing of the intake valve is fixed near the top dead center, and the closing timing of the intake valve is controlled (earlier). Attention has been paid to a device that performs a non-throttle operation by controlling the intake air amount by performing a closing control), and its development is being promoted.

[0004]

In a normal engine, a throttle valve is used to control the amount of intake air. Therefore, a negative pressure is generated downstream of the throttle valve, and the negative pressure reduces blow-by gas. Ventilation in the crankcase).

However, in a variable valve engine that performs non-throttle operation, since the intake air amount is controlled using a variable valve device, there is no throttle valve, and no negative pressure can be expected. Ventilation cannot be performed, which has a large effect on engine oil deterioration.

[0006] In view of such circumstances, an object of the present invention is to provide a blow-by gas reducing apparatus capable of suitably performing ventilation in a crankcase in a variable valve engine.

[0007]

According to the first aspect of the present invention, there is provided a variable valve engine in which the operation of an intake valve is controlled to control the amount of intake air. The passages are connected at different positions by two lines of piping, and a one-way valve (check valve) is interposed in each piping in a direction opposite to each other to constitute a blow-by gas reduction device of a variable valve engine.

[0008] In the invention according to claim 2, the first pipe provided with a one-way valve that allows a flow toward the intake passage is connected to the vicinity of the intake valve, which is greatly affected by intake pulsation, in the intake passage. A second pipe provided with a one-way valve that allows a flow toward the blow-by gas retaining portion in the inside is connected to the vicinity of an air cleaner that is less affected by intake pulsation in an intake passage.

According to the third aspect of the present invention, the first pipe provided with the one-way valve allowing the flow toward the intake passage is connected to the pressure fluctuation due to the blow-by gas from the piston in the blow-by gas retaining portion in the engine body. A second pipe connected with a large crankcase and having a one-way valve for allowing a flow toward the blow-by gas retaining portion in the engine main body is connected to the second pipe having a small pressure fluctuation in the blow-by gas retaining portion in the engine main body. It is characterized in that it is connected to a part (for example, inside a rocker cover or cylinder head).

[0010]

According to the first aspect of the present invention, the blow-by gas retaining portion and the intake passage in the engine main body are connected at different positions by two pipes, and the first pipe is connected from inside the engine main body. By providing a one-way valve to recirculate blow-by gas to the intake passage,
The blow-by gas in the engine body can be sucked out when a pressure difference from the engine body due to pulsation in the intake passage is generated.

The second pipe connects the intake passage to the inside of the engine main body in order to supply fresh air from the intake passage to the inside of the engine main body. The volume in the engine main body damps pulsation in the intake passage. By providing a one-way valve also in this pipe in order to prevent the occurrence of reverse flow (pulsation damping) due to pulsation can be prevented.

Therefore, even in a variable valve engine that generates almost no negative pressure, ventilation in the crankcase can be performed by utilizing the pulsation in the intake passage, and deterioration of engine oil and the like can be prevented.

According to the second aspect of the present invention, the first pipe for guiding the blow-by gas from the inside of the engine body is connected to the vicinity of the intake valve, which is greatly affected by the intake pulsation, in the intake passage to supply fresh air into the engine body. The ventilation effect can be increased by connecting the second pipe to the vicinity of the air cleaner where the influence of the intake pulsation is small in the intake passage.

According to the third aspect of the present invention, the first pipe for guiding the blow-by gas to the intake passage is provided with a large pressure fluctuation due to the blow-by gas from the piston in the blow-by gas retaining portion in the engine body (in other words, high pressure). A second pipe, which is connected to the crankcase and supplies fresh air from the intake passage side, is connected to the crankcase to increase pressure in the blow-by gas stagnation portion in the engine body. By connecting to a small portion (a portion that is not easily affected by pressure fluctuation), the above-described ventilation effect can be increased.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall view of a blow-by gas reducing device for a variable valve engine according to an embodiment of the present invention,
FIG. 2 is a sectional view of a main part in the engine body.

The engine body 1 includes a cylinder block 2,
It comprises a cylinder head 3 and a rocker cover 4.
As shown in FIG. 2, a combustion chamber 6 is formed in the cylinder block 2 and the cylinder head 3 by a piston 5 of each cylinder.

On the cylinder head 3 side of each combustion chamber 6, an intake port 8 and an exhaust port 9 are opened so as to surround the ignition plug 7, and the electromagnetically driven intake valve 10 and the exhaust A valve 11 is provided.

FIG. 3 shows the basic structure of an electromagnetic drive device (variable valve device) for the intake valve 10 and the exhaust valve 11. A plate-shaped mover 32 is attached to a valve shaft 31 of the valve body 30, and the mover 32 is biased to a neutral position by springs 33 and 34. The valve opening electromagnetic coil 35 is disposed below the movable element 32, and the valve closing electromagnetic coil 36 is disposed above the movable element 32.

Therefore, when the valve is opened, the power supply to the upper valve closing electromagnetic coil 36 is stopped, and then the current is supplied to the lower valve opening electromagnetic coil 35 to attract the movable element 32 to the lower side. As a result, the valve body 30 is lifted to open the valve. vice versa,
When closing the valve, the power supply to the lower valve opening electromagnetic coil 35 is stopped, and then the upper valve closing electromagnetic coil 36 is energized to attract the movable element 32 to the upper side.
Is seated on the seat and the valve is closed.

The engine body 1 has an intake port 8
An intake passage (intake manifold) 12 is attached to communicate with the exhaust port 9, and an exhaust passage (exhaust manifold) 13 is attached to communicate with the exhaust port 9.

The intake passage 12 has an inlet side (intake duct).
An air cleaner 14 is provided in each of the cylinders, and an electromagnetically driven fuel injection valve 16 is provided for each cylinder at a branch portion to each cylinder downstream of a surge tank (volume portion of the intake manifold) 15.

Here, a first pipe 18 is provided for connecting the inside of the crankcase 17 of the cylinder block 2 and the vicinity of the intake valve 10 in the intake passage 12, and the first pipe 18 is connected to the intake passage from the crankcase 17 side. A one-way valve (check valve) 19 that allows only the flow toward the side 12 is interposed.

A second pipe 20 for connecting the vicinity of the air cleaner 14 in the intake passage 12 (downstream of the filter element) with the inside of the rocker cover 4 is provided.
Is provided with a one-way valve (check valve) 21 that allows only a flow from the air cleaner 14 side to the rocker cover 4 side.

That is, the blow-by gas stagnation portion in the engine body 1 and the intake passage 12 are connected to two systems of pipes 18 and 20.
At different positions, and each pipe 18, 2
At 0, one-way valves 19 and 21 are interposed in opposite directions.

A first pipe 18 provided with a one-way valve 19 for allowing a flow toward the intake passage 12 is connected to the intake passage 12 near the intake valve 10 (A) where the influence of intake pulsation is large. A second pipe 20 provided with a one-way valve 21 that allows a flow toward the blow-by gas retaining portion side in the engine body 1 is connected to the vicinity (B) of the air cleaner 14 in the intake passage 12 where the influence of intake pulsation is small. is there.

A first pipe 18 provided with a one-way valve 19 allowing a flow toward the intake passage 12 is connected to a blow-by gas from the piston 5 in the blow-by gas stagnation portion of the engine main body 1 to reduce pressure fluctuation due to blow-by gas from the piston 5. A second pipe 20 connected to the inside (C) of the large crankcase 17 and having a one-way valve 21 interposed therein to allow a flow toward the blow-by gas retaining portion in the engine main body 1 is connected to the blow-by gas retaining in the engine main body 1. The portion is connected to the inside (D) of the rocker cover 4 which is a portion where pressure fluctuation is small.

In other words, the first pipe 18 provided with the one-way valve 19 that allows the flow toward the intake passage 12 is
In the engine body 1, a connection is made from the inside of the crankcase 17 where pressure fluctuation due to blow-by gas from the piston 5 is large to the vicinity of the intake valve 10 where intake pulsation is large in the intake passage 12. A second pipe 20 provided with a one-way valve 21 that allows a flow toward the engine body 1 is connected to the intake passage 12.
Is connected from the vicinity of the air cleaner 14 with small intake pulsation to the inside of the rocker cover 4 with small pressure fluctuation in the engine body 1.

The inside of the cylinder block 2 (crankcase 17), the inside of the cylinder head 3, and the inside of the rocker cover 4 are communicated by a blow-by internal passage 22. In this engine, the control unit 23 opens and closes the electromagnetically driven intake valve 10 and the exhaust valve 11 based on engine operating conditions (mainly, accelerator opening and engine speed) for the purpose of improving fuel efficiency by reducing pump loss. The non-throttle operation is performed by controlling the operation, in particular, by fixing the opening timing IVO of the intake valve 5 near the top dead center and variably controlling the closing timing IVC of the intake valve 5 to control the amount of intake air.

The fuel injection timing and fuel injection amount of the fuel injection valve 16 are controlled based on the engine operating conditions. The fuel injection amount is basically based on the intake air amount measured by an air flow meter (not shown). Thus, the air-fuel ratio is controlled to a desired value.

The ignition timing of the ignition plug 7 is controlled based on the engine operating conditions, and the optimal ignition timing (MB
T) or control to knock limit. In this engine, the blow-by gas retaining portion in the engine body 1 and the intake passage 12 are connected at different positions by two pipes 18 and 20, respectively, and the first pipe 18 is connected from the engine body 1 to the intake passage 12. By providing the one-way valve 19 so as to recirculate the blow-by gas, the blow-by gas in the engine main body 1 is sucked when a pressure difference between the blow-by gas and the engine main body 1 is generated due to the pulsation in the intake passage 12.

The second pipe 20 connects the intake passage 12 with the inside of the engine main body 1 in order to supply fresh air from the intake passage 12 into the engine main body 1. In order to prevent pulsation in the passage 12 from being damped, a one-way valve 21 is also provided in the pipe 20 to prevent backflow (pulsation damping) due to pulsation.

Therefore, even in a variable valve engine that generates almost no negative pressure, ventilation in the crankcase 17 can be performed by utilizing the pulsation in the intake passage 12, and deterioration of engine oil and the like can be prevented.

A first pipe 18 for guiding blow-by gas from inside the engine body 1 is connected to the intake valve 12 near the intake valve 10 having a large intake pulsation (A) in the intake passage 12 to supply fresh air into the engine body 1. 2 The pipe 20 is connected to the intake passage 12
Near the air cleaner 14 with small intake pulsation (B)
4, the above effect can be increased and the ventilation performance of the crankcase 17 can be improved, as can be seen from the image of the pressure fluctuations of the parts A and B shown in FIG.

The first pipe 18 for guiding the blow-by gas toward the intake passage 12 is connected to the blow-by gas from the piston 5 in the blow-by gas stagnation portion of the engine main body 1 where the pressure fluctuation due to the blow-by gas from the piston 5 is large. A second pipe 20 connected to the inside (C) of the crankcase 17 for supplying fresh air from the intake passage 12 side of the blow-by gas retaining portion in the engine body 1 is likely to become a positive pressure due to an increase in the amount of generated gas. By connecting to the inside of the rocker cover 4 (D) where pressure fluctuation is small, as can be seen from the pressure fluctuation image of each part C and D shown in FIG. Can be improved.

Incidentally, a portion of the blow-by gas stagnation portion in the engine main body 1 to which the second pipe 20 is connected, where the pressure fluctuation is small, may be formed in the cylinder head 3. The variable valve operating device is not limited to the electromagnetically driven type, but may be a hydraulically driven type.

[Brief description of the drawings]

FIG. 1 is an overall view of a blow-by gas reduction device for a variable valve engine according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part in an engine body.

FIG. 3 is a basic structural diagram of an electromagnetic drive device of the intake and exhaust valves.

FIG. 4 is an image diagram of pressure fluctuation of each part of the engine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine main body 2 Cylinder block 3 Cylinder head 4 Rocker cover 5 Piston 6 Combustion chamber 7 Spark plug 8 Intake port 9 Exhaust port 10 Electromagnetically driven intake valve 11 Electromagnetically driven exhaust valve 12 Intake passage 13 Exhaust passage 14 Air cleaner 15 Surge Tank 16 Fuel injection valve 17 Crankcase 18 First pipe 19 One-way valve 20 Second pipe 21 One-way valve 22 Blow-by internal passage 23 Control unit

Claims (3)

[Claims] 1. A variable valve engine in which the operation of an intake valve is controlled to control an amount of intake air, wherein a blow-by gas stagnation section in an engine body and an intake passage are connected at different positions by two pipes. A blow-by gas reducing device for a variable valve engine, wherein a one-way valve is interposed in each pipe in a direction opposite to each other. 2. A first pipe provided with a one-way valve for allowing a flow toward the intake passage is connected to a vicinity of the intake valve in the intake passage so as to permit a flow toward the blow-by gas retaining portion in the engine body. The blow-by gas reducing device for a variable valve engine according to claim 1, wherein a second pipe provided with a one-way valve is connected near an air cleaner in an intake passage. 3. A first pipe provided with a one-way valve for allowing a flow toward an intake passage is disposed in a crankcase in which a pressure fluctuation due to blow-by gas from a piston in a blow-by gas retaining portion in an engine body is large. Connecting, connecting a second pipe interposed with a one-way valve that allows a flow toward the blow-by gas retaining portion side in the engine body to a portion of the blow-by gas retaining portion in the engine body where pressure fluctuation is small. The blow-by gas reducing device for a variable valve engine according to claim 1 or 2, wherein: