JP2021156240A - Single cylinder internal combustion engine or piston synchronization-type multicylinder internal combustion engine - Google Patents

Abstract

To make a blowby gas recirculate to an intake system by using a structure which is easy and high in reliability, in a sing cylinder internal combustion engine, or a 4-cycle 2-cylinder internal combustion engine in which a pressure variation occurs in a crank chamber.SOLUTION: A control valve 28 which operates by the negative pressure of a surge tank 15 is interposed in a ventilation passage 24 for making fresh air recirculate to a dynamic valve chamber 26 and a crank chamber 27 from an air cleaner 18. Since an opening of the control valve 28 is proportional to the negative pressure of the surge tank 15, even if the crank chamber 27 is liable to be in a tendency of negative pressure due to the lift of a piston 7, the negative pressure is erased or suppressed by the flow-in of fresh air to the crank chamber 27. Therefore, by maintaining a state that the surge tank 15 is relatively decompressed more than the crank chamber 27, a PCV valve 22 can be open-operated. Since the control valve 28 is simple in a structure of a negative-pressure operation type, a cost can be suppressed, and reliability becomes high.SELECTED DRAWING: Figure 1

Description

The present invention relates to a single-cylinder internal combustion engine or a multi-cylinder internal combustion engine in which a plurality of pistons move up and down in synchronization, and is particularly characterized by a blow-by gas processing technique.

Internal combustion engines are classified into single-cylinder and multi-cylinder engines according to the number of cylinders (cylinder bores). Occurs. On the other hand, in a 4-cycle 2-cylinder internal combustion engine, the stroke is generally shifted by 360 degrees by moving the two pistons up and down in synchronization, but in this case as well, pressure fluctuations occur in the crank chamber as in the case of a single cylinder. ..

In the reciprocating internal combustion engine, there is a phenomenon that a part of the combustion gas blows into the crankcase regardless of the number of cylinders, so the blow-by gas blown into the crankcase is passed through the oil separator chamber to collect the oil here. , The blow-by gas from which the oil is removed is returned to the intake system (intake manifold) by the PCV passage.

In this case, the return control of blow-by gas is performed by a PCV valve that opens by negative pressure, and in a naturally aspirated internal combustion engine that is not equipped with a supercharger, the blow-by gas is returned to the intake system at any time and the supercharger. In the internal combustion engine equipped with the above, the supercharging is cut and the engine returns to a negative pressure state as in the case of deceleration.

However, in a single-cylinder internal combustion engine or a 4-cycle 2-cylinder internal combustion engine in which pressure fluctuations occur in the crankcase as described above, there is a phenomenon that the negative pressure in the crankcase becomes smaller than the negative pressure in the intake system. Even if the intake manifold of the system has a negative pressure, the PCV valve may not open and the blow-by gas may not return to the intake manifold.

Regarding this point, Non-Patent Document 1 provides a ventilation passage for sending intake air to the crankcase from a portion of the intake system upstream of the throttle valve, and allows the intake air to flow only to the crankcase to prevent backflow. A one-sided valve (check valve) and an electromagnetic on-off valve (flow control valve) are provided, and when the crank chamber becomes negative pressure, the on-off valve is opened to send intake air to the crank chamber to open and operate the PCV valve. Is disclosed.

Honda R & D Technical Review Vol.16 No.2 pp. 165-170

In Non-Patent Document 1, it can be said that while pressure fluctuation in the crankcase is unavoidable, the operation of the PCV valve can be ensured even when the crankcase is in a negative pressure state, and the return of the throttle valve can be ensured. There is a problem that the cost increases because an expensive electromagnetic on-off valve is required and a control circuit is also required, and if the cable breaks or the control circuit breaks down, blow-by gas cannot be eliminated. rice field.

The present invention has been made to solve this problem.

The present invention relates to a single-cylinder internal combustion engine or a multi-cylinder internal combustion engine in which a plurality of pistons move up and down in synchronization.
"It is equipped with a PCV passage that returns the blow-by gas that has blown through the crankcase to the downstream side of the throttle valve in the intake system, and a ventilation passage that communicates with the part of the intake system that is upstream of the throttle valve and the crankcase. Crankcase
The PCV passage is provided with a PCV valve that opens by negative pressure, while
In the ventilation passage, a control valve that operates by a negative pressure on the downstream side of the throttle valve in the intake system is arranged so that the closing amount increases in proportion to the negative pressure on the downstream side of the throttle valve. ing"
It is configured as.

In the present invention, the intake system and the crank chamber may be connected by a pipeline as a ventilation passage, or the intake system and the valve chamber are connected by an external ventilation passage, while the valve chamber and the crank chamber are connected to the cylinder head and the crank chamber. It is also possible to communicate with the cylinder block by an internal ventilation passage and insert a control valve into the external ventilation passage. Further, in the present invention, it is preferable to provide a one-sided valve for preventing backflow in the ventilation passage.

In the present invention, when a portion of the intake system downstream of the throttle valve such as the intake manifold (for example, the intake manifold) becomes a negative pressure state or the negative pressure becomes higher toward the vacuum side, the control valve opens or opens. Can be increased, and fresh air can be introduced into the crank chamber or the amount of introduction can be increased.

Therefore, even if the crank chamber tends to have a negative pressure type due to the rise of the piston, the negative pressure can be prevented or the degree of the negative pressure can be suppressed by introducing fresh air. As a result, the PCV valve can be opened and operated while maintaining the state in which the intake manifold is relatively depressurized with respect to the crankcase. As a result, the return of blow-by gas can be ensured even in a single-cylinder internal combustion engine or a piston-synchronized multi-cylinder internal combustion engine.

And since the control valve operates by the negative pressure of the intake system, the structure is simple and no circuit is required. Therefore, the cost can be significantly reduced compared to the solenoid valve, and it cannot be operated due to cable disconnection or circuit breakage. The reliability can be improved by eliminating such a situation. In addition, since no electric power is used, there is an advantage that the load on the battery does not increase.

It is an overall schematic diagram of an embodiment. It is a figure which shows the structure of the control valve, (A) is the sectional view seen from the direction of FIG.

Next, an embodiment in which the present invention is embodied in a 4-cycle 2-cylinder internal combustion engine for automobiles will be described with reference to the drawings. In the following, the front-back and left-right terms are used to specify the direction, but the front-back direction is the crank axis direction, and the left-right direction is the direction orthogonal to the crank axis and the cylinder bore axis. Regarding the front and the back, the side where the timing chain is arranged is the front, and the side where the mission case is arranged is the back.

(1). Overview The basic structure of the internal combustion engine is the same as the conventional one, and as the engine body, the cylinder block 1 and the cylinder head 2 fixed to the upper surface thereof, the head cover 3 fixed to the upper surface of the cylinder head 2, and the cylinder block 1 It is provided with an oil pan 4 fixed to the lower surface of the cylinder. The front surfaces of the cylinder block 1 and the head cover 3 are covered with a front cover (not shown), and a timing chain is arranged in a space surrounded by the front cover, the cylinder block 1 and the head cover 3.

A crankshaft 5 is rotatably held in the cylinder block 1 via a crankcap, and a piston 7 slidably inserted into the cylinder bore 6 and a crankpin 8 of the crankshaft 5 are relative to each other by a connecting rod 9. It is connected freely.

The cylinder head 2 has an intake port 10 having a start end opened to the intake side surface 2a and an end opening to the cylinder bore 6, and an exhaust port 11 having the start end opened to the cylinder bore 6 and the end opening to the exhaust side surface 2b. It is formed. The intake valve 12 of the intake port 10 is opened and closed, and the exhaust port 11 is opened and closed by the exhaust valve 13.

An intake manifold 14 is fixed to the intake side surface 2a of the cylinder head 2, and an exhaust manifold or an exhaust turbocharger (neither is shown) is fixed to the exhaust side surface 2b of the cylinder head 2. The intake manifold 14 includes a surge tank 15 and two branch passages 16 branched from the surge tank 15. A throttle valve 17 is fixed to the surge tank 15, and the branch passage 16 is connected to an intake port 10.

The internal combustion engine includes an air cleaner 18 as a member of the intake system, a duct-shaped intake passage 19 is connected to the clean chamber 18a of the air cleaner 18, and the intake passage 19 is connected to the throttle valve 17. To be precise, the throttle valve 17 includes a tubular throttle body, a butterfly type valve body, and a motor (actuator) for driving the valve body, and the opening degree of the valve body is set to an ECU (engine control unit). It is controlled by the unit).

A PCV separator chamber 20 into which blow-by gas flows is provided on one side of the cylinder block 1, and the PCV separator chamber 20 and the surge tank 15 are connected by a PCV passage 21. Although the PCV separator chamber 20 is provided with a PCV valve 22 that opens under negative pressure, the PCV valve 22 can be provided at any part of the PCV passage 21. The PCV separator chamber 20 may be provided in the head cover 3.

(2). Ventilation structure While the clean chamber 18a of the air cleaner 18 and the head cover 3 are connected by an external ventilation passage 24, an internal ventilation passage 25 is formed in the cylinder head 2 and the cylinder block 1 to allow intake air. It flows into the crank chamber 27 via the valve chamber 26. A control valve 28 that opens due to the negative pressure of the surge tank 15 and a valve 29 that prevents backflow to the air cleaner 18 are interposed in the external ventilation passage 24. On the other hand, the valve 29 is arranged on the upstream side of the control valve 28. The starting end of the external ventilation passage 24 may be connected to the intake passage 19.

The structure of the control valve 28 is shown in FIG. The control valve 28 includes a valve cylinder 31 in which a rod-shaped (plunger-shaped) valve body 30 is slidably fitted so as not to rotate, and an inlet port 32 and an outlet port 33 that communicate with the valve cylinder 31 and open in opposite directions. And have. An input port 34 is opened at one end of the valve cylinder 31, one end of an input passage 35 made of a hose or a tube is connected to the input port 34, and the other end of the input passage 35 is connected to a surge tank 15. There is.

The other end of the valve cylinder 31 is closed by the lid 36, and the valve body 30 is urged in the direction of the lid 36 by a spring (compression coil spring) 37. Then, when the surge tank 15 becomes negative pressure, the valve body 30 is pulled toward the input passage 35 against the spring 37. Therefore, the valve body 30 is provided with a communication hole 38 opened in a direction orthogonal to the axis thereof.

In the state where the valve body 30 is fully advanced by the spring 37 (when it hits the lid 36), the communication hole 38 as a whole is separated from the inlet port 32 and the outlet port 33, and therefore the valve chamber 26 and the crank chamber 27. There is no supply of fresh air to. On the other hand, when the valve body 30 is pulled by the negative pressure and retreats against the spring 37, the communication area between the communication hole 38 and the inlet port 32 and the outlet port 33 increases in proportion to the degree of retreat, and the valve When the body 30 is fully retracted, the communication hole 38 and the inlet port 32 and the exit port 33 are fully communicated with each other.

Since the strokes of the two pistons 7 are shifted by 360 degrees but move up and down in synchronization with each other, the internal pressure of the crank chamber 27 tends to fluctuate alternately between positive pressure and negative pressure at 180 degree intervals. On the other hand, in the intake manifold 14, a negative pressure increase due to the intake stroke and a negative pressure decrease due to the compression stroke occur at 360-degree intervals. Therefore, the cycle of pressure fluctuation differs between the intake manifold 14 and the crank chamber 27.

However, in the present embodiment, when the intake manifold 14 is in a negative pressure state (or the negative pressure increases toward the vacuum side), the ventilation volume to the crank chamber 27 increases, and the crank chamber 27 tends to have a negative pressure. In this case, the negative pressure can be eliminated or reduced to maintain the relatively depressurized state of the intake manifold 14. Therefore, the PCV valve 22 can be opened and operated to return the blow-by gas to the intake manifold 14.

Since the control valve 28 has a simple structure in which the valve body 30 is urged by a spring 37, the cost can be significantly suppressed as compared with the solenoid valve, the operation can be ensured, and the reliability is excellent. .. The control valve 28 can be attached to the head cover 3 or the surge tank 15, and has excellent flexibility in mounting position.

Although the embodiments of the present invention have been described above, the present invention can be embodied in various ways. For example, the control valve is not limited to the rod-shaped valve body type, but a needle valve type or a butterfly valve type can also be adopted. It is also possible to directly connect the air cleaner or the intake passage and the crank chamber by the ventilation passage without providing the internal ventilation passage. Further, when the internal ventilation passage is provided, the chain arrangement space surrounded by the front cover can also be used as the internal ventilation passage.

The present invention can be embodied in a single-cylinder internal combustion engine or a multi-cylinder internal combustion engine in which a plurality of pistons move up and down in synchronization. Therefore, it can be used industrially.

1 Cylinder block 2 Cylinder head 3 Head cover 7 Piston 10 Intake port 11 Exhaust port 14 Intake manifold 15 Surge tank 16 Branch passage 17 Throttle valve 18 Air cleaner 19 Intake passage 20 Oil separator chamber 21 PCV passage 22 PCV valve 24 External ventilation passage 25 Internal ventilation Passage 28 Control valve 29 One-sided valve 30 Valve body 31 Valve cylinder 37 Spring

Claims (1)

A single-cylinder internal combustion engine or a multi-cylinder internal combustion engine in which multiple pistons move up and down in synchronization.
It is equipped with a PCV passage that returns the blow-by gas that has blown through the crankcase to the downstream side of the throttle valve in the intake system, and a ventilation passage that communicates with the part of the intake system that is upstream of the throttle valve and the crankcase. ,
The PCV passage is provided with a PCV valve that opens by negative pressure, while
In the ventilation passage, a control valve that operates by a negative pressure on the downstream side of the throttle valve in the intake system is arranged so that the closing amount increases in proportion to the negative pressure on the downstream side of the throttle valve. ing,
Single-cylinder or piston-synchronized multi-cylinder internal combustion engine.

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