JP6951180B2 - Engine piston - Google Patents

Description

The present invention relates to engine pistons.

Conventionally, there is known a technique of driving an electric supercharger while the engine is stopped to compress and raise the temperature of air to warm up the engine (for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2003-307134

In the technique described in Patent Document 1, the air compressed by the electric supercharger is introduced into the cylinder via the intake passage and the intercooler, but the progress of warm-up varies depending on the position of the piston in the cylinder. there is a possibility.

Therefore, an object of the present invention is to provide an engine piston capable of suppressing variation in the progress of warm-up when air for warm-up is introduced into the engine.

In order to solve the above problems, the piston of the engine of the present invention has a communication passage that connects the crown surface facing the combustion chamber and the back surface facing the crank chamber, and an open position that opens the communication passage when the engine is stopped. It includes a movable member that moves between a closed position that closes the communication passage when the engine is driven, and the movable member is moved from the open position to the closed position by the hydraulic pressure of the engine oil .

Further, a hydraulic chamber formed so as to intersect the continuous passage and to which engine oil is supplied when the engine is driven may be provided, and the movable member may be housed in the hydraulic chamber.

Further, it is provided in the hydraulic chamber and includes an elastic member that urges the movable member in the direction from the closed position to the open position. The movable member resists the urging force of the elastic member by the hydraulic pressure of the engine oil when the engine is driven. The engine may be moved from the open position to the closed position, and may be moved from the closed position to the closed position by the urging force of the elastic member when the engine is stopped.

Further, the oil circuit may include an oil circuit for communicating the hydraulic chamber and the piston pin hole into which the piston pin is inserted, and the oil circuit may circulate engine oil to the hydraulic chamber.

Further, in order to solve the above problems, the piston of the engine of the present invention has a communication passage for communicating the crown surface facing the combustion chamber and the back surface facing the crank chamber, and the communication passage is opened when the engine is stopped to open the engine. It is provided with a movable member that closes the communication passage when the vehicle is driven.

According to the present invention, it is possible to suppress variations in the progress of warm-up when warm-up air is introduced into the engine.

It is the schematic explaining the engine warm-up system in 1st Embodiment. It is a figure for demonstrating the crankshaft. It is a figure for demonstrating the connecting rod. It is a figure for demonstrating a piston pin. It is a figure for demonstrating a piston. It is a schematic cross-sectional view (VI-VI cross-sectional view in FIG. 5B) of a piston. It is explanatory drawing which shows the air flow in warm-up. It is a figure which shows the map of efficiency at the time of driving an electric supercharger. It is a flowchart explaining the engine warm-up process at the time of engine stop. It is a flowchart explaining the engine warm-up process at the time of starting an engine. It is a flowchart explaining the engine warm-up process at the time of starting an engine in 2nd Embodiment. It is a figure which shows the modification in 1st Embodiment.

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. The dimensions, materials, other specific numerical values, etc. shown in the embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are designated by the same reference numerals to omit duplicate description, and elements not directly related to the present invention are not shown. do.

(First Embodiment)
FIG. 1 is a schematic diagram illustrating an engine warm-up system 100 according to the first embodiment. In FIG. 1, the signal flow is indicated by a broken line arrow.

As shown in FIG. 1, the engine 1 is provided in the engine warm-up system 100. The engine 1 is a horizontally opposed 4-cylinder engine in which cylinder bores 3a formed in two cylinder blocks 3 are arranged so as to face each other with the crankshaft 2 interposed therebetween.

A crankcase 4 is integrally formed in the cylinder block 3, and a cylinder head 5 is fixed to the side opposite to the crankcase 4. The crankshaft 2 is rotatably supported in a crank chamber 6 formed by two crankcases 4.

A piston 8 connected to the crankshaft 2 via a connecting rod 7 is slidably housed in the cylinder bore 3a. Then, in the engine 1, a space surrounded by the cylinder bore 3a, the cylinder head 5, and the crown surface 8a of the piston 8 (see FIG. 5) is formed as the combustion chamber 9.

The cylinder head 5 is formed so that the intake port 10 and the exhaust port 11 communicate with the combustion chamber 9. The tip of the intake valve 12 is located between the intake port 10 and the combustion chamber 9, and the tip of the exhaust valve 13 is located between the exhaust port 11 and the combustion chamber 9.

Further, the engine 1 is provided with an intake valve cam 15 and an exhaust valve cam 16 in a cam chamber surrounded by the cylinder head 5 and the head cover 14. The intake valve cam 15 is in contact with the other end of the intake valve 12, and rotates to move the intake valve 12 in the axial direction. As a result, the intake valve 12 opens and closes between the intake port 10 and the combustion chamber 9. The exhaust valve cam 16 is in contact with the other end of the exhaust valve 13, and rotates to move the exhaust valve 13 in the axial direction. As a result, the exhaust valve 13 opens and closes between the exhaust port 11 and the combustion chamber 9.

An intake flow path 18 including an intake manifold 17 is communicated with the upstream side of the intake port 10. Further, an exhaust flow path 20 including an exhaust manifold 19 is communicated with the downstream side of the exhaust port 11. The exhaust gas discharged from the combustion chamber 9 is collected by the exhaust manifold 19 via the exhaust port 11 and guided to the exhaust flow path 20.

The intake flow path 18 is provided with an air cleaner 21, an intake control valve 25, a compressor impeller 22c of an electric supercharger 22, which will be described later, an intercooler front valve 28, an intercooler 23, a throttle valve 24, and an intake manifold 17 in this order from the upstream side. Be done. Here, of the intake flow paths 18, the upstream side of the compressor impeller 22c is referred to as an upstream intake flow path 18a, and the downstream side of the compressor impeller 22c is referred to as a downstream intake flow path 18b.

The electric supercharger 22 includes a motor 22a, a shaft 22b, and a compressor impeller 22c. The motor 22a is driven by being supplied with electric power. The shaft 22b is connected to the motor 22a and is rotated by the drive of the motor 22a. The compressor impeller 22c is connected to the shaft 22b and rotates integrally with the shaft 22b.

Further, the compressor impeller 22c is rotated by driving the motor 22a to compress the air (intake air) from which impurities such as dust and dirt have been removed by the air cleaner 21 and supply the air (intake air) to the downstream intake flow path 18b.

The intercooler 23 cools the air compressed and heated by the compressor impeller 22c. The cooled air is guided to the combustion chamber 9 via the throttle valve 24, the intake manifold 17, and the intake port 10.

The opening degree of the throttle valve 24 is adjusted by an actuator (not shown) to change the flow rate of air supplied to the combustion chamber 9.

The intake control valve 25 is in an open state while the engine 1 is being driven, and is passed through the air cleaner 21 to the downstream side without adjusting the flow rate of air sucked from the outside. Further, the intake control valve 25 adjusts the flow rate of air (intake) sucked from the outside by adjusting the opening degree during engine warm-up, which will be described in detail later.

Further, the intake flow path 18 is provided with an air bypass flow path 26 that bypasses the compressor impeller 22c. One end of the air bypass flow path 26 is connected between the intake control valve 25 and the compressor impeller 22c in the upstream intake flow path 18a. The other end of the air bypass flow path 26 is connected between the intercooler 23 and the throttle valve 24 in the downstream intake flow path 18b.

An air bypass valve 27 is interposed in the air bypass flow path 26. The air bypass valve 27 adjusts the flow rate of the compressed air flowing through the air bypass flow path 26 by adjusting the opening degree. The air bypass valve 27 is opened when the driver releases the accelerator and the throttle valve 24 is closed when the engine 1 is driven, to prevent the pressure in the downstream intake flow path 18b from becoming excessive. The detailed control of the air bypass valve 27 during the warm-up of the engine 1 will be described later.

The downstream intake flow path 18b is provided with a crankcase flow path 29 that introduces air compressed by the electric supercharger 22 into the crankcase 4 (inside the crankcase 6). One end of the crankcase flow path 29 is connected to the upstream side of the valve before the intercooler 28 in the downstream intake flow path 18b. Further, the other end of the crankcase flow path 29 is connected to the crankcase 4 and communicates with the crankcase 6.

Further, the engine warm-up system 100 is provided with a crankcase valve mechanism 200 including an intercooler front valve 28 and a crankcase valve 30.

The intercooler front valve 28 is provided on the upstream side of the intercooler 23 in the downstream intake flow path 18b. The intercooler front valve 28 is in an open state while the engine 1 is being driven, and is passed to the downstream side without adjusting the air flow rate. Further, the valve 28 in front of the intercooler is closed during engine warm-up, which will be described in detail later, so that air is not circulated to the downstream side (intercooler 23 side).

The crankcase valve 30 is interposed at the upstream end (compressor impeller 22c side) of the crankcase flow path 29. The crankcase valve 30 is in a closed state while the engine 1 is being driven, and does not allow air (intake) to flow through the crankcase flow path 29. Further, the crankcase valve 30 adjusts the flow rate of air flowing through the crankcase flow path 29 by adjusting the opening degree during engine warm-up, which will be described in detail later. The detailed control of the intercooler front valve 28 and the crankcase valve 30 will be described later.

In the engine 1, a mixture of the intake air guided to the combustion chamber 9 and the fuel injected from an injector (not shown) is ignited at a predetermined timing by an ignition plug (not shown) provided in the cylinder head 5 and burned. Will be done. Due to such combustion, the piston 8 reciprocates in the cylinder bore 3a, and the reciprocating motion is converted into the rotational motion of the crankshaft 2 through the connecting rod 7.

Further, the exhaust gas generated by combustion is discharged to the outside of the vehicle through the exhaust port 11 and the exhaust flow path 20. The exhaust flow path 20 is provided with a catalyst 31 on the upstream side and a catalyst 32 on the downstream side. The catalyst 31 on the upstream side and the catalyst 32 on the downstream side purify the exhaust gas flowing through the exhaust flow path 20. The catalyst 31 on the upstream side and the catalyst 32 on the downstream side may be a filter device having a catalyst function.

Further, one end of the EGR (Exhaust Gas Recirculation) flow path 33 is connected between the catalyst 31 on the upstream side and the catalyst 32 on the downstream side in the exhaust flow path 20. The other end of the EGR flow path 33 is connected between the intake control valve 25 and the compressor impeller 22c in the upstream intake flow path 18a. The EGR flow path 33 recirculates a part of the exhaust gas flowing through the exhaust flow path 20 to the upstream intake flow path 18a (hereinafter, the recirculated exhaust gas (air) is referred to as "EGR gas").

The EGR cooler 34 and the EGR valve 35 are provided in the EGR flow path 33 in this order from the upstream side. The EGR cooler 34 cools the EGR gas. The EGR valve 35 adjusts the flow rate of the EGR gas flowing through the EGR flow path 33 by adjusting the opening degree. The detailed control of the EGR valve 35 will be described later.

Further, the EGR flow path 33 is provided with a bypass flow path 36 that bypasses the EGR cooler 34. A flow path switching valve 37 is provided at a position connecting the upstream side of the bypass flow path 36 and the EGR flow path 33. The flow path switching valve 37 switches the flow path so that the EGR gas (air) flows through either the EGR cooler 34 or the bypass flow path 36.

Further, the engine warm-up system 100 is provided with an in-cylinder communication mechanism 38 that communicates and shuts off the inside of the crankcase 4 and the combustion chamber 9.

The in-cylinder communication mechanism 38 is composed of a crankshaft 2, a connecting rod 7, a piston 8, and a piston pin 40 (see FIG. 4) that rotatably supports the piston 8 with respect to the connecting rod 7. Here, the in-cylinder communication mechanism 38 will be described with reference to FIGS. 2 to 6.

FIG. 2 is a diagram for explaining the crankshaft 2. As shown in FIG. 2, the crankshaft 2 is integrally formed with a crank journal 2a, a crank arm 2b, and a crank pin 2c. The crank journal 2a is rotatably supported by the crankcase 4 via bearings. The crank arm 2b is provided between the crank journal 2a and the crank pin 2c, and eccentricizes the crank pin 2c with respect to the crank journal 2a. As many crankpins 2c as the number of pistons 8 (here, four) are provided to rotatably support the connecting rod 7.

In the crankpin 2c, an oil hole 2e is formed in the center of the crankshaft 2 in the axial direction so as to penetrate from the oil flow path through which the engine oil flows inside the crankshaft 2 to the outer peripheral surface 2d. The oil hole 2e guides the engine oil flowing through the oil flow path to the outer peripheral surface 2d. Further, on the outer peripheral surface 2d of the crank pin 2c, an oil groove 2f is formed in the center of the crankshaft 2 in the axial direction along the circumferential direction. The oil groove 2f is connected to the oil hole 2e on the outer peripheral surface 2d of the crank pin 2c. Therefore, the oil groove 2f is filled with the engine oil that has passed through the oil hole 2e and reached the outer peripheral surface 2d of the crankpin 2c.

FIG. 3 is a diagram for explaining the connecting rod 7. As shown in FIG. 3, in the connecting rod 7, the big end 7a, the small end 7b, and the connecting rod shaft 7c are integrally formed. The big end 7a is rotatably supported by the crankshaft 2 by forming a coupling hole 7d having a diameter slightly larger than the outer diameter of the crankpin 2c on the crankshaft 2 and coupling the crankpin 2c to the coupling hole 7d. Will be done. The small end 7b is formed with an insertion hole 7e having a diameter slightly larger than the outer diameter of the piston pin 40, and the piston pin 40 is inserted into the insertion hole 7e so that the piston 8 can be rotated through the piston pin 40. To support. The connecting rod shaft 7c is located between the big end 7a and the small end 7b and connects the big end 7a and the small end 7b.

An oil circuit 7f is formed in the connecting rod shaft 7c to communicate the coupling hole 7d of the big end 7a and the insertion hole 7e of the small end 7b. The oil circuit 7f is formed at the center of the connecting rod shaft 7c in the width direction (axial direction of the crankshaft 2). In the oil circuit 7f, when the connecting rod 7 is supported by the crankshaft 2, one end 7g is opened at a position facing the oil groove 2f formed in the crankpin 2c. As a result, the engine oil filled in the oil groove 2f of the crankpin 2c is guided from one end 7g to the other end 7h through the oil circuit 7f.

Further, in the oil circuit 7f, when the piston 8 is supported via the piston pin 40 described later, the other end 7h opens at a position facing the piston pin groove 40f (see FIG. 4) formed in the piston pin 40. doing.

FIG. 4 is a diagram for explaining the piston pin 40. As shown in FIG. 4, the piston pin 40 is formed in a substantially cylindrical shape having a hollow inside (hollow portion). An oil circuit 40a is provided along the axial direction between the inner peripheral surface and the outer peripheral surface of the piston pin 40. The oil circuit 40a is formed by scraping from one side surface 40b of the piston pin 40 so as not to reach the other side surface 40c along the axial direction, and one side surface 40b side is sealed with a plug 40d. NS.

Further, the piston pin 40 is formed with a communication hole 40e and a piston pin groove 40f at the center in the axial direction. The communication hole 40e penetrates from the oil circuit 40a to the outer peripheral surface. Further, the piston pin groove 40f is formed on the outer peripheral surface of the piston pin 40 in the circumferential direction. The communication hole 40e and the piston pin groove 40f are connected to each other on the outer peripheral surface of the piston pin 40. Therefore, the engine oil that has passed through the oil circuit 7f of the connecting rod 7 is discharged from the other end 7h of the oil circuit 7f into the piston pin groove 40f, and is guided to the oil circuit 40a through the piston pin groove 40f and the communication hole 40e.

Further, the piston pin 40 is provided with two communication holes 40g penetrating from the oil circuit 40a to the outer peripheral surface. The two communication holes 40g are formed at positions symmetrical with respect to the center in the axial direction of the piston pin 40.

Further, the piston pin 40 is provided with two piston pin grooves 40h. The piston pin groove 40h is formed on the outer peripheral surface of the piston pin 40 over the circumferential direction. The piston pin groove 40h is connected to the communication hole 40g on the outer peripheral surface of the piston pin 40. Therefore, the piston pin groove 40h is filled with engine oil that has passed through the oil circuit 40a and the communication hole 40g and reached the outer peripheral surface of the piston pin 40. By penetrating the communication hole 40e and the communication hole 40g to the hollow portion of the piston pin 40 and sealing both ends of the hollow portion with plugs without providing the oil circuit 40a, the hollow portion can be used as a substitute for the oil circuit 40a. You may use it.

FIG. 5 is a diagram illustrating the piston 8. FIG. 5A is a cross-sectional view (perspective view) of the piston 8. FIG. 5B is a schematic view of the piston 8 as viewed from the crown surface 8a side (in FIG. 5A, from above in the height direction). In addition, in FIG. 5A, the elastic member 41 is shown without having a cross section. Further, in FIG. 5B, in order to clarify the positional relationship, the outer shape of the piston 8 is shown by a thin line, and the structure and parts related to the inside of the piston 8 are shown by a thick line. Further, in the following, as shown in FIG. 5, the sliding direction of the piston 8 is the height direction, the direction in which air flows from the intake port 10 to the exhaust port 11 is the moving direction, and the direction perpendicular to the moving direction is the width direction. It is explained as.

The piston 8 is a two-stage cavity piston having a first cavity 8b and a second cavity 8c. The first cavity 8b and the second cavity 8c are recesses formed in the crown surface 8a. The first cavity 8b has a substantially circular shape when viewed from the crown surface 8a side, and is formed at the center of the axis of the piston 8. The second cavity 8c is a recess deeper than the first cavity 8b. The second cavity 8c has a substantially elliptical shape that is long in the moving direction when viewed from the crown surface 8a side, and the center (center when viewed from the height direction) is located on the intake port 10 side with respect to the first cavity 8b. There is. The first cavity 8b functions as an intake guide that promotes the formation of a tumble flow, and the second cavity 8c functions as a guide that guides the sprayed fuel to a spark plug (not shown).

Further, the piston 8 is formed with a piston pin hole 8e, an oil circuit 8f, a hydraulic chamber 8g, and a communication passage 39. The piston pin hole 8e has a diameter slightly larger than the outer diameter of the piston pin 40, and the piston pin 40 is inserted through the piston pin hole 8e. One end of the oil circuit 8f communicates with the piston pin hole 8e, and the other end communicates with the hydraulic chamber 8g.

The oil circuit 8f is formed at a position communicating with the piston pin hole 8e at a position facing the piston pin groove 40h of the piston pin 40 when the piston pin 40 is inserted into the piston 8 (for example, FIG. 5 (see FIG. 5). Two) as shown in b). Therefore, the engine oil filled in the piston pin groove 40h is guided to the hydraulic chamber 8g through the oil circuit 8f.

The hydraulic chamber 8g is formed along a moving direction orthogonal to the sliding direction of the piston 8 (in the height direction in FIGS. 5A and 5B). Specifically, the hydraulic chamber 8g is composed of the same width portion 8h and the narrowed width portion 8j. The same width portion 8h is formed in a cubic shape that is long in the moving direction. One end 8k of the hydraulic chamber 8g is formed in a square shape. The narrowed width portion 8j is continuously formed at the other end of the same width portion 8h. The narrowed width portion 8j is formed in a triangular prism shape in which the width direction becomes shorter as the width portion 8j is separated from the same width portion 8h in the moving direction. The piston 8 is cut once in the radial direction (in the moving direction and the width direction in FIGS. 5A and 5B) at the position where the piston ring groove 8p is formed, and the hydraulic chamber 8g is formed. .. Then, the cut portion is welded by electron beam welding after the hydraulic chamber 8 g is formed (after the elastic member 41 and the movable member 42 are accommodated).

In the hydraulic chamber 8g, the oil circuit 8f is communicated with the other end 8n side (narrowed width portion 8j). Specifically, in the hydraulic chamber 8g, the narrowed width portion 8j communicates with the oil circuit 8f. Further, the hydraulic chamber 8g intersects (orthogonally) the communication passage 39 at a position separated from one end 8k in the moving direction by a predetermined distance.

Further, an elastic member 41 and a movable member 42 are provided in the hydraulic chamber 8g. One end of the elastic member 41 is provided in contact with one end 8k in the hydraulic chamber 8g. The elastic member 41 is a stretchable member, and for example, a spring is used. Further, the length of the elastic member 41 (the length in the moving direction in FIG. 5A) exceeds the continuous passage 39 from one end 8k in the hydraulic chamber 8g when it is not expanded and contracted (natural length). Has a length of up to.

The movable member 42 is movably provided in the direction in which the hydraulic chamber 8g extends (moving direction in FIG. 5A) within the hydraulic chamber 8g. The movable member 42 is formed in a cubic shape. The movable member 42 is formed so that the length in the height direction and the length in the width direction are substantially the same as the length in the height direction and the length in the width direction of the same width portion 8h (hydraulic chamber 8g). Therefore, the movable member 42 does not enter the narrowed width portion 8j when moving in the hydraulic chamber 8g.

Further, the length of the movable member 42 in the width direction and the moving direction is formed to be at least longer than the diameter of the communication passage 39 described later. The detailed function (movement) of the movable member 42 will be described later.

Further, an oil circuit 42a is formed inside the movable member 42. The oil circuit 42a is formed in an L shape extending in the height direction and the moving direction. One end 42b of the oil circuit 42a is open to the bottom surface of the movable member 42 (the surface of FIG. 5A facing the back surface 8m). Further, one end 42b of the oil circuit 42a is provided at the center of the movable member 42 in the width direction and at a position separated from the side surface 42e of the movable member 42 facing the elastic member 41 by a predetermined distance, and details will be described later. In addition, when the engine 1 is driven, it communicates with the communication passage 39.

The other end 42c of the oil circuit 42a is open to the side surface 42d of the movable member 42 facing the other end 8n of the hydraulic chamber 8g. The other end 42c of the oil circuit 42a is provided at the center of the side surface 42d of the movable member 42. The diameter of the oil circuit 42a may be any size as long as the movable member 42 can move against the urging force of the elastic member 41.

The communication passage 39 is formed so as to communicate the crown surface 8a facing the combustion chamber 9 and the back surface 8m facing the crank chamber 6. The communication passage 39 is on the exhaust port 11 side in the moving direction on the crown surface 8a, and is at a position different from, for example, a place where the second cavity 8c is formed (it does not overlap the place where the second cavity 8c is formed). Is formed in. Further, the communication passage 39 is provided so as to be orthogonal to the hydraulic chamber 8g. The communication passage 39 is formed to have a diameter shorter than the length of the hydraulic chamber 8g in the width direction, and as shown in FIG. It intersects the hydraulic chamber 8g so that everything is located within the width of the chamber 8g (in the width direction in FIG. 5B).

FIG. 6 is a schematic cross-sectional view of the piston 8 (VI-VI cross-sectional view in FIG. 5B). FIG. 6A shows a state when the engine 1 is driven, and FIG. 6B shows a state when the engine 1 is stopped. As in FIG. 5A, the elastic member 41 is shown without having a cross section.

When the engine 1 is being driven, the engine oil is circulated in the order of the crank shaft 2, the oil circuit 7f of the connecting rod 7, the oil circuit 40a of the piston pin 40, and the oil circuit 8f of the piston 8 by the in-cylinder communication mechanism 38. , Guided into the hydraulic chamber 8g. Then, the engine oil guided to the hydraulic chamber 8g has the movable member 42 at one end of the hydraulic chamber 8g against the urging force of the elastic member 41 by the electric pressure (indicated by the white arrow in FIG. 6A). It is moved to the 8k side (elastic member 41 side). Then, the movable member 42 moves to a position (blocking position) at which the communication passage 39 is closed (blocked). The urging force of the elastic member 41 is set to be weaker than the force received from the movable member 42 by the flood control.

When the movable member 42 moves to the closed position, the communication passage 39 is closed. As a result, the piston 8 can prevent the combustion chamber 9 and the crank chamber 6 from communicating with each other when the engine 1 is being driven.

Further, one end 42b of the oil circuit 42a communicates with the communication passage 39 below the hydraulic chamber 8g. Then, the engine oil is discharged to the outside of the piston 8 via the oil circuit 8f, the oil circuit 42a, and the communication passage 39, as shown by the black arrows in FIG. 6A. By discharging the engine oil to the outside of the piston 8, new engine oil is always guided to the oil circuit 8f while the engine 1 is being driven. As a result, the piston 8 (particularly the crown surface 8a) is constantly cooled by the engine oil circulating in the piston 8.

Then, when the engine 1 is stopped, the supply of the engine oil is stopped, so that the engine oil stored in the hydraulic chamber 8g is discharged to the outside of the piston 8. Therefore, as shown in FIG. 6B, the movable member 42 is on the other end 8n side of the hydraulic chamber 8g due to the urging force of the elastic member 41 (indicated by the white arrow in FIG. 6B). It moves to a position (open position) where the communication passage 39 is opened (communication). That is, the communication passage 39 is opened (communication). As a result, the piston 8 can communicate with the inside of the crankcase 4 and the combustion chamber 9 as shown by the black arrows in FIG. 6B.

As described above, the in-cylinder communication mechanism 38 can shut off the crank chamber 6 and the combustion chamber 9 by closing (blocking) the communication passage 39 when the engine 1 is being driven.

On the other hand, the communication mechanism 38 in the cylinder can open (communicate) the communication passage 39 when the engine 1 is stopped, and allow the crank chamber 6 and the combustion chamber 9 to communicate with each other.

By the way, it is essentially undesirable for the combustion chamber 9 to be provided with a hole such as a communication passage 39. Therefore, if the communication passage 39 is provided in the piston 8 which is a part of forming the combustion chamber 9, the combustion efficiency may deteriorate.

On the other hand, if the engine is warmed up inefficiently, the warm-up of the engine 1 may be slowed down, the engine 1 may not be warmed up sufficiently, and the exhaust gas may be deteriorated or the fuel consumption may be deteriorated. .. That is, when the communication passage 39 is provided, the combustion efficiency of the combustion chamber 9 and the engine warm-up are in a trade-off relationship. Therefore, the communication passage 39 of the present embodiment is located at a position other than the second cavity 8c, which is a portion of the crown surface 8a of the piston 8 that does not adversely affect the combustion efficiency (so as not to overlap with the second cavity 8c). ) Provided. As a result, the influence on the combustion efficiency in the combustion chamber 9 can be minimized, and the efficiency of engine warm-up, which will be described later, can be improved.

Returning to FIG. 1, the engine warm-up system 100 is provided with a control device 110. The control device 110 includes a first pressure sensor (pressure sensor) 50, a second pressure sensor 52, a first temperature sensor 54, a second temperature sensor 56, a third temperature sensor 58, a fourth temperature sensor 60, and an engine start switch sensor. 62 is connected.

The first pressure sensor 50 is provided between the intercooler 23 and the throttle valve 24 in the downstream intake flow path 18b, and measures the pressure in the downstream intake flow path 18b. Further, the first pressure sensor 50 transmits a detection signal corresponding to the pressure (pressure P1) in the downstream intake flow path 18b to the control device 110.

The second pressure sensor 52 is provided on the downstream side of the connection point of the EGR flow path 33 in the upstream side intake flow path 18a, and measures the pressure in the upstream side intake flow path 18a. Further, the second pressure sensor 52 transmits a detection signal corresponding to the pressure (pressure P2) in the upstream intake flow path 18a to the control device 110.

The first temperature sensor 54 is provided in the cylinder block 3 and measures the temperature of the cooling water flowing in the engine 1. Further, the first temperature sensor 54 transmits a detection signal corresponding to the temperature (temperature T1) in the engine 1 to the control device 110.

The second temperature sensor 56 is provided on the upstream side of the intake control valve 25 in the upstream intake flow path 18a, and measures the temperature of the intake air (intake). Further, the second temperature sensor 56 transmits a detection signal corresponding to the temperature (temperature T2) of the intake air (outside air) to the control device 110.

The third temperature sensor 58 is provided in the intake manifold 17 and measures the temperature of the air flowing through the intake manifold 17. Further, the third temperature sensor 58 transmits a detection signal corresponding to the temperature (temperature T3) in the intake manifold 17 to the control device 110.

The fourth temperature sensor 60 is provided on the catalyst 31 on the upstream side and measures the temperature of the air (exhaust) flowing through the catalyst 31 on the upstream side. Further, the fourth temperature sensor 60 transmits a detection signal corresponding to the temperature (temperature T4) in the catalyst 31 on the upstream side to the control device 110.

When the engine start switch (not shown) is turned on, the engine start switch sensor 62 transmits an engine start switch on signal indicating that the engine start switch is turned on to the control device 110. Further, when the engine start switch is turned off, the engine start switch sensor 62 transmits an engine start switch off signal indicating that the engine start switch is turned off to the control device 110.

The control device 110 is, for example, an ECU (Engine Control Unit), and is composed of a central processing unit (CPU), a ROM in which a program or the like is stored, a semiconductor integrated circuit including a RAM as a work area, and the like, and constitutes the entire engine 1. Control. In addition to controlling the operation of the entire vehicle including the engine 1, the control device 110 also controls the drive control unit 112, the intake / exhaust valve control unit 114, the valve control unit 116, the flow path switching valve control unit 118, and the electric supercharger. It also functions as a unit 120. Hereinafter, the specific operation of the engine warm-up system 100 will be described.

FIG. 7 is an explanatory diagram showing the flow of air during warm-up. In FIG. 7, black arrows indicate the flow of air flowing through the intake system. In FIG. 7, white arrows indicate the flow of air flowing through the exhaust system. Here, the intake system refers to the intake port 10, the intake flow path 18, and the air bypass flow path 26, and the exhaust system refers to the exhaust port 11, the exhaust flow path 20, the EGR flow path 33, and the bypass flow path 36. Point to.

Here, when the engine start switch is turned on (receives the engine start switch on signal), the drive control unit 112 starts the engine 1, but when the engine 1 is at a low temperature, the viscosity of the engine oil Is high, and the startability of the engine 1 is lowered. Therefore, in the engine warm-up system 100, when the engine start switch is turned on, if the engine warm-up execution condition is satisfied, the engine warm-up is executed. The engine warm-up execution condition is that the temperature (temperature T1) in the engine 1 is lower than a predetermined temperature which is a preset low temperature. The warm-up by the engine warm-up system 100 is performed for the first purpose of stabilizing the combustion at the time of starting even when the outside air temperature is low by warming up the combustion chamber 9 of the engine 1.

When the drive control unit 112 receives the engine start switch off signal sent from the engine start switch sensor 62, the drive control unit 112 stops the engine 1. At this time, in the intake / exhaust valve control unit 114, both the intake valve 12 and the exhaust valve 13 are in an open state regardless of whether or not the engine warm-up is executed at the start of the engine 1 as a step before the engine warm-up is executed. The engine 1 is stopped and controlled so as to be in the (overlapping state). As a result, in the engine 1, the state in which the intake port 10 and the combustion chamber 9 are communicated with each other is maintained. Further, in the engine 1, the state in which the exhaust port 11 and the combustion chamber 9 are communicated with each other is maintained. Further, when the engine 1 is stopped, the in-cylinder communication mechanism 38 communicates the crank chamber 6 and the combustion chamber 9 with each other via the communication passage 39.

After that, when the engine start switch is turned on (the engine start switch on signal is received), the drive control unit 112 determines whether the engine warm-up execution condition is satisfied. Then, when it is determined that the engine warm-up execution condition is satisfied, the drive control unit 112 causes each unit of the control device 110 to execute the engine warm-up without starting the engine 1.

When the engine warm-up is started, the valve control unit 116 opens the throttle valve 24, the air bypass valve 27, the crankcase valve 30, and the EGR valve 35. Further, the valve control unit 116 closes the intake control valve 25 and the intercooler front valve 28.

Further, the flow path switching valve control unit 118 controls the flow path switching valve 37 so that air flows through the bypass flow path 36.

Then, the electric supercharger control unit 120 drives the electric supercharger 22 with a predetermined constant electric power. At this time, when the electric supercharger 22 is driven by the intake control valve 25 in the closed state and the air bypass valve 27 and the EGR valve 35 in the open state, the compressor impeller 22c enters the air bypass flow path 26. And air is taken in from the EGR flow path 33.

In this way, the intake valve 12 and the exhaust valve 13 are maintained in the open state, and the open / closed state of each valve is controlled, so that the inside of the engine 1 (combustion) is shown by the black arrow and the white arrow in FIG. A circulation flow path through which air circulates, including the chamber 9), will be formed.

Here, the compression ratio of the electric supercharger 22 will be described. FIG. 8 is a diagram showing a map of efficiency when the electric supercharger 22 is driven. In FIG. 8, the vertical axis shows the pressure ratio and the horizontal axis shows the flow rate. The pressure ratio is a ratio of the pressure of the air flowing through the electric supercharger 22 to the pressure of the air compressed by the electric supercharger 22. The flow rate is the mass flow rate of air compressed by the electric supercharger 22. The control of the crankcase valve 30 will be described with reference to FIG. Further, in FIG. 8, the broken line indicates the efficiency (power efficiency) of the electric supercharger 22. The power efficiency lines a to d show the same power efficiency. Further, in FIG. 8, the alternate long and short dash line indicates the electric power input to the electric supercharger 22. The power line indicated by each alternate long and short dash line indicates equal power.

As shown in FIG. 8, the power efficiency of the electric supercharger 22 increases toward the center of the figure. For example, in the inner region surrounded by the power efficiency line a, the electric supercharger 22 is driven with an efficiency of 85% or more. Further, the electric supercharger 22 is powered with an efficiency of 80% to 85% in the inner region surrounded by the power efficiency line b and a efficiency of 75% to 80% in the inner region surrounded by the power efficiency line c. The inner region surrounded by the efficiency line d is driven with an efficiency of 70% to 75%.

The inner region A surrounded by the power efficiency line a indicates the power efficiency when the electric supercharger 22 is normally driven. As described above, in the inner region surrounded by the power efficiency line a, the electric supercharger 22 is driven with an efficiency of, for example, 85% or more. At that time, the heat generated by driving the electric supercharger 22 is about 10%. Therefore, the electric supercharger 22 can efficiently compress the air by driving it in the region A.

On the other hand, as the distance from the power efficiency line a increases in the order of the power efficiency line b, the power efficiency line c, and the power efficiency line d, the amount of heat generated by driving the electric supercharger 22 increases. Although the power efficiency of the electric supercharger 22 deteriorates as the amount of heat generated increases, the energy generated by the heat generation is transmitted to the air flowing through the intake flow path 18, and the temperature of the air rises.

Here, in FIG. 8, the region surrounded by the solid line shown by low is inefficient (low) with respect to the region surrounded by the solid line shown by high (when the electric supercharger 22 is normally driven). Area of efficiency. In FIG. 8, the left side region is referred to as region B, and the right side region is referred to as region C. However, in the area B and the area C, the efficiencies of the electric supercharger 22 are substantially the same.

In the area B and the area C, the amount of heat generated from the electric supercharger 22 is substantially the same. However, when the electric power supplied to the electric supercharger 22 is the same, in the region B, the air is compressed more and the flow rate is reduced as compared with the region A. On the other hand, in the region C, the air is not compressed and the flow rate increases as compared with the region A. Therefore, driving the electric supercharger 22 in the region B can raise the temperature of the air by the amount of the temperature rise due to compression, as compared with the case of driving the electric supercharger 22 in the region C.

Therefore, the crankcase valve 30 is set to a valve diameter such that the electric supercharger 22 is driven in the region B. As a result, the engine warm-up system 100 drives the electric supercharger 22 in the region B where the air temperature is highest, and the engine 1 can be warmed up at an early stage.

Further, since the electric supercharger 22 is driven, the pressure inside the EGR flow path 33 becomes negative. Since the pressure inside the EGR flow path 33 is negative, air is less likely to be discharged downstream from the exhaust flow path 20 (downstream from the catalyst 32 on the downstream side). Therefore, the air once warmed can be used for warming up again without being cooled by the outside air.

Further, in the piston 8, the communication passage 39 is provided so as not to overlap the second cavity 8c. That is, the communication passage 39 is provided on the exhaust port 11 side. Therefore, the air compressed and warmed by the electric supercharger 22 can stay in the combustion chamber 9 for a long time as compared with the case where the air is provided on the intake port 10 side, and the engine 1 can be warmed up earlier. can.

Further, the air compressed and warmed by the electric supercharger 22 by the crankcase flow path 29 flows through the crankcase flow path 29 and is directly guided into the engine 1 (inside the crank chamber 6). Then, the engine 1 is warmed by the heat of the guided air. The air that has passed through the engine 1 flows through the air bypass flow path 26, the exhaust flow path 20 and the EGR flow path 33, and is returned to the upstream intake flow path 18a. Further, the air that has passed through the engine 1 is returned to the upstream intake flow path 18a by bypassing the EGR cooler 34 in the process of flowing through the exhaust flow path 20 and the EGR flow path 33.

By introducing the warmed air directly into the engine 1 in this way, it is possible to warm the engine 1 faster (efficiently) than through the intake flow path 18, the intercooler 23, or the intake manifold 17. can. Further, since the air warmed by the piston 8 (air for warming up) passes through the communication passage 39, it is less likely to be affected by the position of the piston 8 during warming up, and the progress of warming up varies. Can be suppressed.

Then, the electric supercharger control unit 120 warms up the engine 1 until the temperature (temperature T3) in the intake manifold 17 becomes equal to or higher than the threshold value Th1 based on the temperature of the outside air (temperature T2). The threshold Th1 is a value higher than the temperature of the outside air (temperature T2) and differs depending on the temperature of the outside air (temperature T2), and the threshold Th1 when the temperature of the outside air (temperature T2) is low. Is relatively lower than that when the temperature of the outside air (temperature T2) is high.

By the way, when warming up the engine 1, the catalyst 31 on the upstream side can be warmed up at the same time as the engine 1. By warming the catalyst 31 on the upstream side, it is possible to reduce the fuel injection amount immediately after the engine 1 is driven and to accelerate the warm-up, which leads to improvement of fuel efficiency and exhaust gas purification performance.

Therefore, in the engine warm-up system 100, when the engine warm-up heat-retaining condition, which is said to have warmed up the engine 1 and the intake system, is satisfied, the catalyst 31 on the upstream side is warmed up. The engine warm-up heat retention condition is such that the temperature (temperature T3) in the intake manifold 17 is a temperature equal to or higher than the threshold Th1 and the temperature (temperature T4) of the catalyst 31 on the upstream side is set from the preset threshold Th2. Is also low.

When the valve control unit 116 determines that the engine warm-up heat retention condition is satisfied, the valve control unit 116 closes the air bypass valve 27, assuming that the engine 1 and the intake system have been warmed up.

As a result, the air compressed and warmed by the electric supercharger 22 is not circulated to the intake system (black arrow in FIG. 7), but only to the exhaust system (white arrow in FIG. 7). Become. Therefore, the catalyst 31 on the upstream side can be concentrated and warmed up.

Then, the electric supercharger control unit 120 warms the catalyst 31 on the upstream side until the temperature (temperature T4) of the catalyst 31 on the upstream side reaches a temperature equal to or higher than the threshold value Th2.

Then, when the temperature (temperature T3) in the intake manifold 17 becomes the temperature of the threshold Th1 or more and the temperature (temperature T4) of the catalyst 31 on the upstream side becomes the threshold Th2 or more, the drive control unit 112 warms the engine. Assuming that the machine termination condition is satisfied, the upstream catalyst 31 and the engine warm-up are terminated, and the engine 1 is driven (started).

(Engine warm-up process)
Next, the flow of the engine warm-up process by the engine warm-up system 100 will be described. FIG. 9 is a flowchart illustrating an engine warm-up process when the engine 1 is stopped.

First, the drive control unit 112 determines whether or not the engine start switch has been turned off based on the signal transmitted from the engine start switch sensor 62 (S10). Then, if it is determined that the engine start switch is turned off (YES in step S10), the intake / exhaust valve control unit 114 controls the intake valve 12 and the exhaust valve 13 in an open state (overlap state) (S12). After that, the drive control unit 112 stops the engine 1 (S14), and ends the engine warm-up process when the engine 1 is stopped.

On the other hand, when the drive control unit 112 determines that the engine start switch is not turned off (NO in step S10), the drive control unit 112 repeats the process of step S10 until it is determined that the engine start switch is turned off.

FIG. 10 is a flowchart illustrating an engine warm-up process at the time of starting the engine 1. The engine warm-up process at the time of starting the engine 1 is a process executed when the engine start switch is turned on.

When the engine start switch is turned on, the drive control unit 112 determines whether or not the engine warm-up execution condition is satisfied (S20). The temperature T2 may be added to determine whether or not the engine warm-up execution condition is satisfied. In this case, it is determined that the engine warm-up execution condition is satisfied when the temperature T1 and the temperature T2 are equal to or lower than the temperature (threshold value) set for each.

Then, if it is determined that the engine warm-up execution condition is satisfied (YES in step S20), the valve control unit 116 opens the throttle valve 24, the air bypass valve 27, the crank case valve 30, and the EGR valve 35. , The intake control valve 25 and the intercooler front valve 28 are closed (S22). Further, the flow path switching valve control unit 118 controls the flow path switching valve 37 so that air flows through the bypass flow path 36. Then, the electric supercharger control unit 120 drives the electric supercharger 22 with a predetermined electric power (S24).

Then, the valve control unit 116 determines whether or not the temperature T3 is equal to or higher than the threshold value Th1 (S28). Then, if it is determined that the temperature T3 is equal to or higher than the threshold value Th1 (YES in step S28), the valve control unit 116 determines whether or not the temperature T4 is lower than the threshold value Th2 (S30). That is, the valve control unit 116 determines in steps S28 and S30 whether or not the engine warm-up heat retention condition is satisfied.

On the other hand, if it is determined that the temperature T3 is not equal to or higher than the threshold Th1 (less than the threshold Th1) (NO in step S28), it means that the engine 1 has not been warmed up to a sufficient temperature, and the engine 1 is sufficient. The process of step S28 is repeated until it is determined that the temperature has been warmed up to a certain temperature (the temperature T3 becomes the threshold value Th1 or more).

Further, if it is determined that the temperature T4 is not less than the threshold value Th2 (NO in step S30), it means that the catalyst 31 on the upstream side has been warmed up to a sufficient temperature, and the drive control is performed. The unit 112 ends the engine warm-up. Then, the valve control unit 116 closes the crankcase valve 30 and the EGR valve 35, and opens the intake control valve 25 and the intercooler front valve 28. Further, the flow path switching valve control unit 118 controls the flow path switching valve 37 so that air flows through the EGR cooler 34 (S36).

Then, the drive control unit 112 drives (starts) the engine 1 (S38), and ends the engine warm-up process at the time of starting the engine. That is, since the catalyst 31 on the upstream side is also sufficiently warmed up in the process of warming up the engine (because the condition for ending the warm-up of the engine is satisfied), the engine 1 is driven without keeping the engine 1 warm.

Then, if it is determined that the engine warm-up heat retention condition is satisfied (YES in step S28 and step S30), the valve control unit 116 closes the air bypass valve 27 (S32). Next, the valve control unit 116 determines whether or not the temperature T4 is equal to or higher than the threshold value Th2 (S34). Then, if it is determined that the temperature T4 is equal to or higher than the threshold value Th2 (YES in step S34), the drive control unit 112 ends the engine warm-up. Then, the valve control unit 116 closes the crankcase valve 30 and the EGR valve 35, and opens the intake control valve 25 and the intercooler front valve 28. Further, the flow path switching valve control unit 118 controls the flow path switching valve 37 so that air flows through the EGR cooler 34 (S36). Then, the drive control unit 112 drives (starts) the engine (S38), and ends the engine warm-up process at the time of starting the engine 1. That is, the valve control unit 116 determines in steps S28, S30, and S34 whether or not the engine warm-up end condition is satisfied.

On the other hand, if it is determined that the temperature T4 is less than the threshold value Th2 (NO in step S34), the valve control unit 116 repeats the process of step S34. During warm-up by the engine warm-up system 100 before starting the engine, it is difficult to accurately grasp the temperature of the combustion chamber 9 based on the temperature T1 indicating the temperature inside the engine 1 (cooling water temperature). be. Therefore, in the present embodiment, the temperature T3 in the intake manifold 17, in other words, the temperature of the air supplied to the combustion chamber 9, is used to determine the end of engine warm-up. Further, in consideration of the heat capacity of the combustion chamber 9, the elapsed time after the temperature T3 reaches the threshold value Th1 is confirmed. The end of the engine warm-up may be determined based on the temperature T3 and the flow rate history (integrated value of the air flow rate after the start of the engine warm-up).

Further, if it is determined that the engine warm-up execution condition is not satisfied (NO in S20), the electric supercharger control unit 120 starts the engine 1 (S38) and warms up the engine at the time of starting the engine. End the process. The fact that the engine warm-up execution condition is not satisfied means that the engine 1 is not in the cold state. Therefore, since it is not necessary to warm the inside of the engine 1, the drive control unit 112 ends the engine warm-up process at the time of starting the engine without performing the engine warm-up.

With this configuration, the engine warm-up system 100 controls the opening and closing of each valve when the engine 1 is driven in a cold state, and drives the electric supercharger 22. As a result, the air compressed (supercharged) and warmed by the electric supercharger 22 can be directly introduced into the engine 1 (inside the crank chamber 6) by the communication mechanism 38 in the cylinder. In addition, the control of each valve makes it possible to circulate the compressed and warmed air. Therefore, the engine 1 can be warmed up efficiently and early by controlling the communication mechanism 38 in the cylinder and each valve.

(Second Embodiment)
FIG. 11 is a flowchart illustrating an engine warm-up process at the time of starting the engine in the second embodiment. The second embodiment is configured by the engine warm-up system 100 described above, but the control of the valve control unit 116 is different. The description of the control substantially equal to that of the engine warm-up system 100 described above will be omitted.

When it is determined that the engine warm-up execution condition is satisfied (YES in step S20), the valve control unit 116 opens the throttle valve 24, the air bypass valve 27, and the crankcase valve 30. Further, the valve control unit 116 closes the intake control valve 25, the intercooler front valve 28, and the EGR valve 35 (S40).

In this way, the intake valve 12 and the exhaust valve 13 are maintained in the open state, and the open / closed state of each valve is controlled, so that a circulation flow path including the intake system is formed as shown by the black arrow in FIG. Will be done. On the other hand, the circulation flow path including the exhaust system indicated by the white arrow in FIG. 7 is not formed.

Then, the electric supercharger control unit 120 drives the electric supercharger 22 (S24) to warm up the engine. In this case, the air compressed (supercharged) and warmed by the electric supercharger 22 is circulated more through the intake system (black arrows in FIG. 7). Therefore, the intake system can be warmed faster (priority).

Then, when the valve control unit 116 determines that the engine warm-up heat retention condition is satisfied (YES in step S28 and step S30), the valve control unit 116 closes the air bypass valve 27 and opens the EGR valve 35 (S42). Further, the flow path switching valve control unit 118 controls the flow path switching valve 37 so that air flows through the bypass flow path 36. As a result, the circulation flow path including the intake system is closed, while the circulation flow path including the exhaust system is formed, and the catalyst 31 on the upstream side can be concentrated and warmed up.

Therefore, in the engine warm-up system 100 of the second embodiment, the engine 1 and the catalyst 31 on the upstream side can be warmed up intensively. This makes it possible to finish the engine warm-up process earlier.

(Modification example)
FIG. 12 is a diagram showing a modification of the first embodiment. The description of the configuration substantially the same as that of the engine warm-up system 100 described above will be omitted. As shown in FIG. 12, the engine 1 is provided with an engine warm-up system 300. Specifically, the engine warm-up system 300 is newly configured to include an exhaust control valve 302, a heating heater 304, and a control device 310.

The exhaust control valve 302 is provided on the downstream side of the exhaust flow path 20 where the EGR flow path 33 is connected, and on the upstream side of the catalyst 32 on the downstream side. The exhaust control valve 302 is in an open state while the engine 1 is being driven, and is downstream of the exhaust control valve 302 without adjusting the flow rate of air flowing from the upstream side of the exhaust control valve 302 in the exhaust flow path 20. Let it pass to the side. Further, the exhaust control valve 302 adjusts the flow rate of air discharged to the outside through the exhaust flow path 20 by adjusting the opening degree during engine warm-up, which will be described in detail later.

The heating heater 304 is provided on the upstream side of the catalyst 31 on the upstream side in the exhaust flow path 20. The heating heater 304 warms the air (exhaust gas) flowing through the exhaust flow path 20.

In addition to the functions of the control device 110 described above, the control device 310 also newly functions as an exhaust control valve control unit 312 and a heater / heater control unit 314.

The exhaust control valve control unit 312 controls the opening degree of the exhaust control valve 302. The exhaust control valve control unit 312 closes the exhaust control valve 302 after it is determined that the engine warm-up execution condition is satisfied. Therefore, the air flowing through the exhaust flow path 20 is not discharged to the downstream side (outside the engine warm-up system 300) of the catalyst 32 on the downstream side. Therefore, the warmed air can be used again for engine warm-up without being cooled by the outside air (without being discharged to the outside of the engine warm-up system 100). Therefore, the engine 1 can be warmed up more effectively (more aggressively) and at an early stage.

The heating heater control unit 314 heats the heating heater 304. The heater control unit 314 heats the heater 304 after it is determined that the engine warm-up execution condition is satisfied. The temperature of the air compressed and warmed by the electric supercharger 22 drops as it passes through the engine 1. Therefore, the temperature of the air flowing through the exhaust flow path 20 is lower than that of the air passing through the crankcase flow path 29. Therefore, the heating heater 304 is provided in the exhaust flow path 20 to warm the flowing air, thereby raising the temperature of the refluxing air. By raising the temperature of the refluxing air, when the air is compressed again by the electric supercharger 22, it is compressed to a higher temperature. By warming and circulating the recirculated air in this way, the engine 1 can be warmed up more effectively (more aggressively) and at an early stage.

Further, by providing the heating heater 304 on the upstream side of the catalyst 31 on the upstream side in the exhaust flow path 20, the catalyst 31 on the upstream side can be warmed. By warming the catalyst 31 on the upstream side, the catalyst 31 on the upstream side can be activated at an early stage.

Although the preferred embodiment of the present invention has been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such an embodiment. It is clear that a person skilled in the art can come up with various modifications or modifications within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present invention. Will be done.

For example, in the above embodiment, the case where the engine warm-up process is executed when the engine 1 is in the cold state has been described, but the engine warm-up process may be executed even when the engine 1 is not in the cold state.

Further, in the above embodiment, the case where the hydraulic chamber 8g is provided with the same width portion 8h and the narrowed width portion 8j so that the movable member 42 does not block the oil circuit 8f has been described. However, instead of providing the hydraulic chamber 8g with a narrowed width portion 8j whose length in the width direction is shortened, a funnel portion in which both the length in the height direction and the length in the moving direction are shortened may be provided. Alternatively, a protruding portion protruding into the hydraulic chamber 8g may be provided between the connection point with the oil circuit 8f and the movable member 42 in the hydraulic chamber 8g. Alternatively, an elastic member 41 that can be expanded and contracted may be provided at the other end 8n of the hydraulic chamber 8g.

Further, in the above embodiment, the case where the piston pin 40 is provided with two piston pin grooves 40h and the piston 8 is provided with two oil circuits 8f correspondingly has been described. However, the piston pin groove 40h provided on the piston pin 40 and the oil circuit 8f provided on the piston 8 do not necessarily have to be two, and one or three or more may be provided. At least one or more equal number of piston pin grooves 40h and oil circuit 8f may be provided in the piston pin 40 and the piston 8.

Further, in the above embodiment, the case where the hydraulic chamber 8g is provided in the piston 8 at a position (moving direction in FIGS. 5A and 5B) orthogonal to the piston pin 40 has been described. However, the hydraulic chamber 8g may be provided at a position parallel to the piston pin 40 (in the width direction in FIGS. 5A and 5B).

Further, in the above embodiment, the case where the engine warm-up systems 100 and 300 are provided with the bypass flow path 36 bypassing the EGR cooler 34 in the EGR flow path 33 has been described. However, the bypass flow path 36 is not an essential configuration.

Further, in the above embodiment, the case where the first pressure sensor 50 and the second pressure sensor 52 are provided in the engine warm-up systems 100 and 300 and the opening degree of the throttle valve 24 is controlled based on the pressure ratio has been described. .. However, instead of the pressure sensor, the flow rate sensor may be used to derive the flow rate and control the opening degree of the crankcase valve 30.

Further, in the above embodiment, in the engine warm-up systems 100 and 300, the valve control unit 116 controls to close the air bypass valve 27 when it is determined that the engine warm-up heat retention condition is satisfied (step S32 and step). S42) The case has been described. However, when the valve control unit 116 determines that the engine warm-up heat retention condition is satisfied instead of closing the air bypass valve 27, the temperature (temperature T3) in the intake manifold 17 is maintained at a temperature equal to or higher than the threshold Th1. Therefore, the opening degree of the air bypass valve 27 may be controlled (the opening degree may be narrowed down). In this case, the air compressed and warmed by the electric supercharger 22 also flows to the intake system. Therefore, since the warmed-up engine 1 can be kept warm, the engine warm-up process at the time of starting the engine 1 can be completed earlier.

Further, in the above embodiment, the case where the crankcase valve mechanism 200 is composed of the intercooler front valve 28 and the crankcase valve 30 has been described. However, instead of the intercooler front valve 28 and the crankcase valve 30, a crank valve may be provided at a branch position with the crankcase flow path 29 in the downstream intake flow path 18b. In this case, the crank valve switches the flow path so that the intake air (air) flows through either the downstream intake flow path 18b or the crankcase flow path 29, and the intake air (air) flows through the crankcase flow path 29. ) Adjust the flow rate. Then, the valve control unit 116 controls the crank valve, and as described above, circulates the air compressed and warmed by the electric supercharger 22 through the crankcase flow path 29.

Further, in the above modification, the case where the engine warm-up system 300 is further provided with the exhaust control valve 302 and the heating heater 304 has been described. However, it is not necessary to include both the exhaust control valve 302 and the heater 304. At least one of the exhaust control valve 302 and the heater 304 may be provided.

Further, in the above embodiment, the valve diameter of the crankcase valve 30 is set so that the electric supercharger 22 is driven in the region B. However, if the electric supercharger 22 can be driven in the region B, the valve control unit 116 may control the opening degree of the crankcase valve 30, or may adjust the diameter of the communication passage 39.

Further, in the above embodiment, when the intake valve 12 and the exhaust valve 13 are controlled to overlap, the case where the engine 1 is stopped at the crank angle where the intake valve 12 and the exhaust valve 13 overlap has been described. However, for example, a VVT (Variable Valve Timing system) may be used to move the intake valve 12 and the exhaust valve 13 to bring them into an overlapping state when or after the engine 1 is stopped. In that case, when controlling the opening and closing of each valve (step S36), the intake / exhaust valve control unit 114 sets the intake valve 12 and the exhaust valve 13 according to the crank angle when the engine start switch is turned off. Control to return to the opening.

The present invention can be used in an engine warm-up system for warming up an engine.

1 Engine 6 Crank chamber 8 Piston 8a Crown surface 8e Piston pin hole 8f Oil circuit 8g Hydraulic chamber 8m Back surface 9 Combustion chamber 39 Communication chamber 40 Piston pin 41 Elastic member 42 Movable member

Claims (4)

A communication passage that connects the crown surface facing the combustion chamber and the back surface facing the crank chamber,
A movable member that moves between an open position that opens the communication passage when the engine is stopped and a blockade position that closes the communication passage when the engine is driven.
Equipped with a,
The movable member is
An engine piston that is moved from the open position to the closed position by the oil pressure of the engine oil. It is provided with a hydraulic chamber formed so as to intersect the communication passage and to which the engine oil is supplied when the engine is driven.
The movable member is
The piston of the engine according to claim 1 , which is housed in the hydraulic chamber. An elastic member provided in the hydraulic chamber and urging the movable member in a direction from the closed position to the open position is provided.
The movable member is moved from the open position to the closed position by the hydraulic pressure of the engine oil when the engine is driven, against the urging force of the elastic member, and by the urging force of the elastic member when the engine is stopped. The engine piston according to claim 2 , which is moved from the closed position to the open position. An oil circuit that communicates the hydraulic chamber with the piston pin hole into which the piston pin is inserted.
With
The oil circuit
The engine piston according to claim 2 or 3 , wherein the engine oil is circulated to the hydraulic chamber.

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