JP2019065761A - Piston of engine - Google Patents

Abstract

To prevent variation in progression of warming-up upon introducing air for warming-up into an engine.SOLUTION: A piston 8 of an engine 1 comprises: a communication passage 39 communicating between a crestal plane 8a facing a combustion chamber 9 and a back face 8m facing a crank chamber 6; and a movable member 42 configured to move between an open position of opening the communication passage 39 in stop of the engine 1 and a blockage position of blocking the communication passage 39 in drive of the engine 1. Consequently, a piston of the engine is configured to prevent variation in progression of warming-up upon introducing air for warming-up into the engine.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a piston of an engine.

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

JP 2003-307134 A

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

  Then, an object of this invention is to provide the piston of the engine which can suppress that dispersion | variation arises in progress of warm-up when air for warming-up is introduce | transduced into an engine.

  In order to solve the above problems, the piston of the engine according to the present invention has a communication passage communicating the crown surface facing the combustion chamber with the back surface facing the crank chamber, an open position opening the communication passage when the engine is stopped, And a movable member that moves between a closed position that blocks the communication passage when the engine is driven.

  Also, the movable member may be moved from the open position to the closed position by the hydraulic pressure of the engine oil.

  In addition, the communication passage may be formed to intersect the communication passage, and may be provided with a hydraulic chamber to which engine oil is supplied when the engine is driven, and the movable member may be accommodated in the hydraulic chamber.

  The movable member further includes an elastic member provided in the hydraulic chamber and urging the movable member in a direction from the closed position toward 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. It may be moved from the open position to the closed position and from the closed position to the open position by the biasing force of the elastic member when the engine is stopped.

  The hydraulic circuit may further include an oil circuit for communicating the hydraulic pressure chamber with the piston pin hole into which the piston pin is inserted. The oil circuit may cause engine oil to flow through the hydraulic pressure chamber.

  Further, in order to solve the above problems, the piston of the engine of the present invention opens the communication passage when the engine is stopped, and the communication passage connecting the crown surface facing the combustion chamber with the back surface facing the crank chamber And a movable member that closes the communication passage when the motor is driven.

  ADVANTAGE OF THE INVENTION According to this invention, when air for warming-up is introduce | transduced into an engine, it can suppress that dispersion | variation arises in progress of warming-up.

It is a schematic diagram explaining an engine warm-up system in a 1st embodiment. It is a figure for demonstrating a crankshaft. It is a figure for demonstrating a connecting rod. It is a figure for demonstrating a piston pin. It is a figure for demonstrating a piston. It is a schematic sectional drawing (VI-VI sectional drawing in FIG.5 (b)) of a piston. It is explanatory drawing which shows the flow of the air in warming up. It is a figure which shows the map of the efficiency at the time of a motor-driven supercharger driving. It is a flow chart explaining engine warm-up processing at the time of engine stop. It is a flow chart explaining engine warm-up processing at the time of engine starting. It is a flow chart explaining engine warm-up processing at the time of engine starting in a 2nd embodiment. It is a figure which shows the modification in 1st Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values and the like shown in this embodiment are merely examples for facilitating the understanding of the invention, and do not limit the present invention unless otherwise specified. In the specification and the drawings, elements having substantially the same functions and configurations will be denoted by the same reference numerals to omit repeated description, and elements not directly related to the present invention will not be illustrated. Do.

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

  As shown in FIG. 1, the engine warm-up system 100 is provided with an engine 1. The engine 1 is a horizontally opposed four-cylinder engine in which cylinder bores 3a respectively formed in two cylinder blocks 3 sandwiching a crankshaft 2 are opposed to each other.

  A crankcase 4 is integrally formed with 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 accommodated in the cylinder bore 3a. In the engine 1, a space surrounded by the cylinder bore 3 a, the cylinder head 5, and the crown surface 8 a (see FIG. 5) of the piston 8 is formed as a combustion chamber 9.

  An intake port 10 and an exhaust port 11 are formed in the cylinder head 5 so as to 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.

  In the engine 1, an intake valve cam 15 and an exhaust valve cam 16 are provided 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 moves the intake valve 12 in the axial direction by rotating. Thereby, 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 moves the exhaust valve 13 in the axial direction by rotating. Thereby, the exhaust valve 13 opens and closes between the exhaust port 11 and the combustion chamber 9.

  An intake passage 18 including an intake manifold 17 is in communication with the upstream side of the intake port 10. Further, an exhaust flow passage 20 including an exhaust manifold 19 is in communication with the downstream side of the exhaust port 11. Exhaust gas discharged from the combustion chamber 9 is collected by the exhaust manifold 19 through the exhaust port 11 and is led to the exhaust flow passage 20.

  An air cleaner 21, an intake control valve 25, a compressor impeller 22c of the electric supercharger 22 described later, an intercooler front valve 28, an intercooler 23, a throttle valve 24 and an intake manifold 17 are provided in order from the upstream side in the intake passage 18 Be Here, in the intake passage 18, the upstream side of the compressor impeller 22c is referred to as the upstream intake passage 18a, and the downstream side of the compressor impeller 22c is referred to as the downstream intake passage 18b.

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

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

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

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

  The intake control valve 25 is in an open state during operation of the engine 1 and passes downstream without adjusting the flow rate of air sucked from the outside through the air cleaner 21. Further, the intake control valve 25 adjusts the flow rate of air (intake air) sucked from the outside by adjusting the opening degree during engine warm-up described later in detail.

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

  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 passage 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, and prevents the pressure in the downstream side intake passage 18 b from becoming excessive. The detailed control of the air bypass valve 27 during warm-up of the engine 1 will be described later.

  The downstream intake passage 18b is provided with a crankcase passage 29 for introducing the air compressed by the electric turbocharger 22 into the crankcase 4 (inside the crank chamber 6). One end of the crankcase passage 29 is connected upstream of the intercooler front valve 28 in the downstream side intake passage 18b. Further, the other end of the crankcase flow passage 29 is connected to the crankcase 4 and is communicated with the crank chamber 6.

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

  The intercooler front valve 28 is provided upstream of the intercooler 23 in the downstream side intake passage 18b. The intercooler front valve 28 is open during operation of the engine 1, and passes downstream without adjusting the flow rate of air. Further, the intercooler front valve 28 does not flow air downstream (to the intercooler 23 side) by closing during the engine warm-up described later in detail.

  The crankcase valve 30 is interposed at the upstream end (the compressor impeller 22 c side) of the crankcase flow passage 29. The crankcase valve 30 is closed during operation of the engine 1 and does not allow air (intake air) to flow through the crankcase flow passage 29. Further, the crankcase valve 30 adjusts the flow rate of the air flowing through the crankcase flow passage 29 by adjusting the opening degree during engine warm-up described later in detail. 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 intake air introduced to the combustion chamber 9 and fuel injected from an injector (not shown) is ignited at a predetermined timing by an ignition plug (not shown) provided on the cylinder head 5 and burnt. Be done. By this combustion, the piston 8 reciprocates in the cylinder bore 3 a, and the reciprocation is converted to the rotational motion of the crankshaft 2 through the connecting rod 7.

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

  Further, one end of an EGR (Exhaust Gas Recirculation) channel 33 is connected between the upstream catalyst 31 and the downstream catalyst 32 in the exhaust channel 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 side intake flow path 18a. The EGR flow passage 33 causes part of the exhaust gas flowing through the exhaust flow passage 20 to be returned to the upstream intake flow passage 18a (hereinafter, the returned exhaust gas (air) is referred to as "EGR gas").

  In the EGR passage 33, an EGR cooler 34 and an EGR valve 35 are sequentially provided from the upstream side. The EGR cooler 34 cools the EGR gas. The EGR valve 35 adjusts the opening degree to adjust the flow rate of the EGR gas flowing through the EGR passage 33. The detailed control of the EGR valve 35 will be described later.

  Further, the EGR flow passage 33 is provided with a bypass flow passage 36 for bypassing the EGR cooler 34. A flow path switching valve 37 is provided at a position where the upstream side of the bypass flow path 36 and the EGR flow path 33 are connected. The flow path switching valve 37 switches the flow path so as to flow the EGR gas (air) to 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 for communicating and blocking the inside of the crankcase 4 and the combustion chamber 9.

  The in-cylinder communication mechanism 38 is configured by the crankshaft 2, the connecting rod 7, the 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.

  FIG. 2 is a view 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 crankpin 2c. The crank journal 2a is rotatably supported by the crankcase 4 via a bearing. The crank arm 2b is provided between the crank journal 2a and the crankpin 2c, and eccentricizes the crankpin 2c with respect to the crank journal 2a. The crank pins 2 c are provided in the same number (four in this case) as the pistons 8 and rotatably support the connecting rod 7.

  In the crank pin 2c, an oil hole 2e is formed at the center of the crankshaft 2 in the axial direction, from the oil flow path through which the engine oil flows in the crankshaft 2 to the outer peripheral surface 2d. The oil hole 2e leads the engine oil having flowed through the oil flow path to the outer peripheral surface 2d. Further, an oil groove 2f is formed on the outer peripheral surface 2d of the crank pin 2c at the center in the axial direction of the crankshaft 2 so as to extend in the circumferential direction. The oil groove 2f is connected to the oil hole 2e at the outer peripheral surface 2d of the crank pin 2c. Therefore, the oil groove 2f is filled with the engine oil which has flowed through the oil hole 2e and reached the outer peripheral surface 2d of the crank pin 2c.

  FIG. 3 is a view 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 formed with a connecting hole 7d having a diameter slightly larger than the outer diameter of the crank pin 2c in the crankshaft 2, and the crank pin 2c is connected to the connecting hole 7d, thereby rotatably supporting the crankshaft 2 Be done. The small end 7 b is formed with an insertion hole 7 e 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 7 e to freely rotate the piston 8 via 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.

  The connecting rod shaft 7c is formed with an oil circuit 7f that causes the coupling hole 7d of the big end 7a and the insertion hole 7e of the small end 7b to communicate with each other. 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). One end 7g of the oil circuit 7f opens at a position facing the oil groove 2f formed on the crankpin 2c when the connecting rod 7 is supported by the crankshaft 2. As a result, the engine oil filled in the oil groove 2f of the crank pin 2c is led from the one end 7g to the other end 7h through the oil circuit 7f.

  In addition, when the oil circuit 7f supports the piston 8 via a 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 view for explaining the piston pin 40. As shown in FIG. As shown in FIG. 4, the piston pin 40 is formed in a substantially cylindrical shape whose inside is hollow (hollow part). An oil circuit 40 a is provided along the axial direction between the inner and outer peripheral surfaces of the piston pin 40. The oil circuit 40a is formed by scraping the side surface 40b of the piston pin 40 in the axial direction so as not to reach the other side surface 40c, and the side surface 40b is sealed by the plug 40d. Ru.

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

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

  The piston pin 40 is also provided with two piston pin grooves 40 h. The piston pin groove 40 h is formed along the circumferential direction on the outer peripheral surface of the piston pin 40. The piston pin groove 40 h is connected to the communication hole 40 g on the outer peripheral surface of the piston pin 40. Therefore, the piston pin groove 40 h is filled with the engine oil which has flowed through the oil circuit 40 a and the communication hole 40 g and reached the outer peripheral surface of the piston pin 40. The hollow portion can be used as a substitute for the oil circuit 40a by penetrating the communication hole 40e and the communication hole 40g to the hollow portion of the piston pin 40 without providing the oil circuit 40a and sealing both ends of the hollow portion with plugs. It may be used.

  FIG. 5 is a view for explaining 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 side of the crown surface 8a (from above in the height direction in FIG. 5A). In addition, in FIG. 5A, the elastic member 41 is shown without making it a cross section. Moreover, in FIG.5 (b), in order to clarify positional relationship, the external shape of piston 8 is shown by a thin line, and the structure and components regarding the inside of piston 8 are shown by a thick line. 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 movement direction, and the direction perpendicular to the movement direction is the width direction Explain as.

  The piston 8 is a two-stage cavity piston having a first cavity 8 b and a second cavity 8 c. The first cavity 8 b and the second cavity 8 c are depressions formed in the crown surface 8 a. The first cavity 8 b has a substantially circular shape when viewed from the crown surface 8 a side, and is formed at the axial center of the piston 8. The second cavity 8c is a depression 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 viewed from the height direction) is located closer to the intake port 10 than the first cavity 8b. There is. The first cavity 8b functions as a guide for intake air that promotes the formation of tumble flow, and the second cavity 8c functions as a guide for guiding the sprayed fuel to a spark plug (not shown).

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

  The oil circuit 8 f is formed at a position facing the piston pin groove 40 h of the piston pin 40 when the piston pin 40 is inserted into the piston 8 at a position communicating with the piston pin hole 8 e (for example, 2) as shown in b). Therefore, the engine oil filled in the piston pin groove 40h is led to the hydraulic pressure 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 (the height direction in FIGS. 5A and 5B). Specifically, the hydraulic pressure chamber 8g includes the same width portion 8h and the reduced width portion 8j. The same width portion 8h is formed in a cube shape long in the movement direction. One end 8k of the hydraulic chamber 8g is formed in a square. The narrowed portion 8j is formed continuously to the other end of the same width portion 8h. The narrowed portion 8j is formed in a triangular prism shape whose width direction is shortened as it is separated from the same width portion 8h in the moving direction. The piston 8 is once cut in the radial direction (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 pressure chamber 8g is formed (after the elastic member 41 and the movable member 42 are accommodated).

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

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

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

  Further, the length in the width direction and the movement direction of the movable member 42 is formed longer than at least 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 42 a is formed inside the movable member 42. The oil circuit 42a is formed in an L shape extending in the height direction and the movement direction. One end 42 b of the oil circuit 42 a is opened at the bottom surface (the surface facing the back surface 8 m in FIG. 5A) of the movable member 42. Further, one end 42b of the oil circuit 42a is provided at a position separated by a predetermined distance from the center in the width direction of the movable member 42 and the side surface 42e of the movable member 42 opposed to the elastic member 41. And communicates with the communication passage 39 when the engine 1 is driven.

  The other end 42 c of the oil circuit 42 a is opened at a side surface 42 d opposite to the other end 8 n of the movable chamber 42 in the hydraulic chamber 8 g. 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 biasing force of the elastic member 41.

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

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

  When the engine 1 is driven, the engine oil is circulated by the cylinder internal communication mechanism 38 in the order of the crankshaft 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 , Led to the hydraulic chamber 8g. The engine oil introduced to the hydraulic chamber 8g is hydraulically (shown by a white arrow in FIG. 6A) against the biasing force of the elastic member 41 to move the movable member 42 to one end of the hydraulic chamber 8g. It is moved to the 8 k side (elastic member 41 side). Then, the movable member 42 moves to a position (closed position) where the communication passage 39 is closed (blocked). The biasing force of the elastic member 41 is set to be weaker than the force received from the movable member 42 by the hydraulic pressure.

  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 driven.

  Further, one end 42b of the oil circuit 42a communicates with the communication passage 39 below the hydraulic pressure chamber 8g. Then, the engine oil is discharged to the outside of the piston 8 through the oil circuit 8f, the oil circuit 42a and the communication passage 39 as shown by the solid arrows in FIG. 6A. By discharging the engine oil out of the piston 8, a new engine oil is always introduced to the oil circuit 8f while the engine 1 is in operation. As a result, the piston 8 (particularly the crown surface 8 a) is always cooled by the engine oil flowing in the piston 8.

  Then, when the engine 1 stops, the supply of engine oil is stopped, so the engine oil stored in the hydraulic pressure chamber 8g is discharged out of the piston 8. Therefore, as shown in FIG. 6 (b), the movable member 42 is on the other end 8n side of the hydraulic chamber 8g by the biasing force of the elastic member 41 (indicated by a white arrow in FIG. 6 (b)) The communication passage 39 is moved to the open position (open position). That is, the communication passage 39 is opened (communicated). Thus, the piston 8 can communicate the inside of the crankcase 4 with the combustion chamber 9 as shown by the solid arrows in FIG. 6B.

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

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

  By the way, the provision of a hole such as the communication passage 39 for the combustion chamber 9 is inherently undesirable. Therefore, if the communication passage 39 is provided in the piston 8 which is a part forming the combustion chamber 9, the combustion efficiency may be deteriorated.

  On the other hand, if the inefficient engine warm-up is performed, warm-up of the engine 1 may be delayed or the engine 1 may not be sufficiently warmed, which may cause deterioration of exhaust gas, fuel efficiency, etc. . 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 according to the present embodiment is located at a position other than the second cavity 8c which is the place which does not adversely affect the combustion efficiency among the crown surface 8a of the piston 8 (not to overlap with the second cavity 8c). ) Provided. Thereby, the influence on the combustion efficiency in the combustion chamber 9 can be minimized, and the efficiency of the engine warm-up described later can be improved.

  Referring back 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 are connected.

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

  The second pressure sensor 52 is provided downstream 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 passage 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 according 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 side intake flow passage 18a, and measures the temperature of the air (intake air) taken in. The second temperature sensor 56 also transmits a detection signal to the control device 110 according to the temperature (temperature T2) of the intake air (outside air).

  The third temperature sensor 58 is provided in the intake manifold 17 and measures the temperature of the air flowing in 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 upstream catalyst 31 and measures the temperature of air (exhaust gas) flowing in the upstream catalyst 31. Further, the fourth temperature sensor 60 transmits a detection signal corresponding to the temperature (temperature T4) in the upstream catalyst 31 to the control device 110.

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

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

  FIG. 7 is an explanatory view showing the flow of air during warm-up. Black arrows in FIG. 7 indicate the flow of air flowing through the intake system. White arrows in FIG. 7 indicate the flow of air flowing through the exhaust system. Here, the intake system refers to the intake port 10, the intake passage 18, and the air bypass passage 26, and the exhaust system refers to the exhaust port 11, the exhaust passage 20, the EGR passage 33, and the bypass passage 36. Point to.

  Here, when the engine start switch is turned on (the engine start switch on signal is received), 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 reduced. Therefore, in the engine warm-up system 100, when the engine warm-up execution condition is satisfied when the engine start switch is turned on, 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 at which the temperature is preset. The warm-up by the engine warm-up system 100 is performed by warming up the combustion chamber 9 of the engine 1 as a first object to stabilize the combustion at the start even when the outside air temperature is low.

  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, both the intake valve 12 and the exhaust valve 13 are open regardless of whether or not the engine warm-up is performed at the start of the engine 1 as a step before the engine warm-up. The engine 1 is controlled to stop so as to be in the (overlap state). Thereby, in the engine 1, the state where the intake port 10 and the combustion chamber 9 are in communication is maintained. Further, in the engine 1, the state in which the exhaust port 11 and the combustion chamber 9 are in communication is maintained. Further, when the engine 1 is stopped, the in-cylinder communication mechanism 38 causes the crank chamber 6 and the combustion chamber 9 to communicate 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 part of the control device 110 to perform engine warm-up without starting the engine 1.

  When 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 the air flows in the bypass flow path 36.

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

  As described above, the intake valve 12 and the exhaust valve 13 are maintained in the open state, and the open / close state of each valve is controlled, whereby the inside of the engine 1 is A circulation channel through which air circulates is formed, including the chamber 9).

  Here, the compression ratio of the electric turbocharger 22 will be described. FIG. 8 is a diagram showing a map of the efficiency when the electric supercharger 22 is driven. In FIG. 8, the vertical axis indicates the pressure ratio, and the horizontal axis indicates the flow rate. The pressure ratio is the ratio of the pressure of the air flowing through the electric turbocharger 22 to the pressure of the air compressed by the electric turbocharger 22. The flow rate is the mass flow rate of the air compressed by the electric supercharger 22. Control of the crankcase valve 30 will be described with reference to FIG. Moreover, the broken line in FIG. 8 indicates the efficiency (power efficiency) of the electric turbocharger 22. The respective power efficiency lines a to d show equal power efficiency. Further, in FIG. 8, an alternate long and short dash line indicates the power input to the electric supercharger 22. Power lines shown by respective one-dotted lines indicate equal power.

  As shown in FIG. 8, the power efficiency of the electric turbocharger 22 becomes higher toward the center in the figure. For example, in the inner area surrounded by the power efficiency line a, the electric supercharger 22 is driven at an efficiency of 85% or more. In addition, the electric supercharger 22 is motive power with an efficiency of 80% to 85% in the inner area surrounded by the power efficiency line b and an efficiency of 75% to 80% in the inner area surrounded by the power efficiency line c. In the inner region surrounded by the efficiency line d, driving is performed with an efficiency of 70% to 75%.

  An inner area A surrounded by the power efficiency line a indicates the power efficiency when the electric supercharger 22 is driven normally. As described above, in the inner region surrounded by the power efficiency line a, the electric turbocharger 22 is driven at 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 air by driving in the region A.

  On the other hand, as the power efficiency line b, the power efficiency line c, and the power efficiency line d become farther from the power efficiency line a in this order, the amount of heat generated by the drive of the electric supercharger 22 increases. Although the power efficiency of the electric supercharger 22 deteriorates with the rise of the calorific value, the energy due to the heat generation is transmitted to the air flowing through the intake flow passage 18, and the temperature of the air rises.

  Here, in FIG. 8, the area surrounded by the solid line indicated by low is not efficient (low) with respect to the area surrounded by the solid line indicated by high (when the electric supercharger 22 is driven normally). Efficiency) area. In FIG. 8, the region on the left side is referred to as region B, and the region on the right side is referred to as region C. However, in the region B and the region C, the efficiencies of the electric turbocharger 22 are approximately equal.

  In the area B and the area C, the calorific value generated from the electric supercharger 22 is substantially the same. However, if the electric power supplied to the electric turbocharger 22 is the same, air is compressed more in area B than in area A, and the flow rate decreases. On the other hand, in the region C, air is not compressed as compared with the region A, and the flow rate increases. Therefore, driving the electric supercharger 22 in the area B can make the temperature of the air higher by the temperature increase due to compression than in the case where the electric supercharger 22 is driven in the area C.

  Therefore, the crankcase valve 30 is set to such a valve diameter that the electric turbocharger 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 temperature of the air is the highest, and the engine 1 can be warmed up early.

  In addition, since the electric turbocharger 22 is driven, the inside of the EGR passage 33 has a negative pressure. The negative pressure in the EGR passage 33 makes it difficult for the air to be discharged downstream of the exhaust passage 20 (downstream of the downstream catalyst 32). 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, 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 it is provided on the intake port 10 side, and the engine 1 can be warmed up earlier. it can.

  Further, the air compressed and heated by the electric turbocharger 22 by the crankcase flow passage 29 flows through the crankcase flow passage 29 and is directly introduced into the engine 1 (in the crank chamber 6). Then, the engine 1 is warmed by the heat of the introduced air. The air having passed through the engine 1 flows through the air bypass flow passage 26 or the exhaust flow passage 20 and the EGR flow passage 33, and is returned to the upstream side intake flow passage 18a. Further, the air that has passed through the engine 1 bypasses the EGR cooler 34 and is recirculated to the upstream side intake flow passage 18 a in the process of flowing through the exhaust flow passage 20 and the EGR flow passage 33.

  Thus, by introducing the warmed air directly into the engine 1, the engine 1 can be warmed up more efficiently (efficiently) than in the case where the intake flow passage 18, the intercooler 23, and the intake manifold 17 are used. it can. In addition, since the air warmed in the piston 8 (air for warm-up) passes through the communication passage 39, it becomes difficult to be affected by the position of the piston 8 at the time of warm-up, and the progress of warm-up is uneven. 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 Th1 based on the temperature (temperature T2) of the outside air. The threshold Th1 is a value higher than the temperature of the outside air (temperature T2), and is different 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 outside air temperature (temperature T2) is high.

  By the way, when the engine 1 is warmed up, the upstream catalyst 31 can be warmed up simultaneously with the engine 1. By warming the catalyst 31 on the upstream side, it is possible to reduce the fuel injection amount immediately after driving of the engine 1 and to accelerate the warm-up, leading to the improvement of the fuel efficiency and the improvement of the exhaust gas purification performance.

  Therefore, in the engine warm-up system 100, the warm-up of the upstream catalyst 31 is executed when the engine warm-up keeping condition is satisfied, in which the engine 1 and the intake system are warmed up. The engine warm-up keeping condition is 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 preset from the threshold Th2. Is also low.

  If the valve control unit 116 determines that the engine warm-up keeping condition is satisfied, the valve control unit 116 closes the air bypass valve 27 on the assumption that the engine 1 and the intake system are warmed up.

  As a result, the air compressed and heated by the electric turbocharger 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 upstream catalyst 31 can be concentrated and warmed up.

  Then, the electric turbocharger control unit 120 warms up the upstream catalyst 31 until the temperature (temperature T4) of the upstream catalyst 31 becomes a temperature equal to or higher than the threshold Th2.

  Then, when the temperature in the intake manifold 17 (temperature T3) is equal to or higher than the threshold Th1 and the temperature (temperature T4) of the upstream catalyst 31 is equal to or higher than the threshold Th2, the drive control unit 112 The upstream catalyst 31 and engine warm-up are terminated on condition that the engine termination condition is satisfied, 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 the engine start switch is 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 has been turned off (YES in step S10), the intake and exhaust valve control unit 114 controls the intake valve 12 and the exhaust valve 13 to the open state (overlap state) (S12). Thereafter, 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 process of step S10 is repeated until it is determined that the engine start switch is turned off.

  FIG. 10 is a flow chart for explaining an engine warm-up process at the start of the engine 1. The engine warm-up process at the start of the engine 1 is a process that is executed when the engine start switch is turned on.

  When the engine start switch is turned on, the drive control unit 112 determines whether the engine warm-up execution condition is satisfied (S20). The temperature T2 may be added to the determination as to whether 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 temperatures (threshold values) set for the respective temperatures.

  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 crankcase valve 30, and the EGR valve 35. 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 the air flows in the bypass flow path 36. And the electric supercharger control part 120 drives the electric supercharger 22 by predetermined electric power (S24).

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

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

  Further, if it is determined that the temperature T4 is not less than the threshold Th2 (equal to or higher than the threshold Th2) (NO in step S30), the upstream catalyst 31 is 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 the 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 engine warming up completion condition is satisfied), the engine 1 is driven without keeping the engine 1 warm.

  Then, if it is determined that the engine warm-up keeping 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 the temperature T4 is equal to or higher than the threshold Th2 (S34). Then, if it is determined that temperature T4 is equal to or higher than threshold value Th2 (YES in step S34), drive control unit 112 ends 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 the 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 step S28, step S30, and step S34 whether or not the engine warm-up termination condition is satisfied.

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

  Further, when it is determined that the engine warm-up execution condition is not satisfied (NO in S20), electric supercharger control unit 120 starts engine 1 (S38), and warms up the engine at the time of start of the engine. End the process. The fact that the engine warm-up execution condition is not established 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 processing at the time of starting the engine without performing the engine warm-up.

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

Second Embodiment
FIG. 11 is a flow chart for explaining an engine warm-up process at engine start-up 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. Description of control substantially equivalent to that of the above-described engine warm-up system 100 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).

  As described above, the intake valve 12 and the exhaust valve 13 are maintained in the open state, and the open / close state of each valve is controlled, thereby forming a circulation flow path including the intake system as shown by the solid arrows in FIG. It will be done. On the other hand, the circulation flow path including the exhaust system shown 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 by the intake system (indicated by the solid arrows in FIG. 7). Therefore, it is possible to warm the intake system earlier (preferentially).

  When the valve control unit 116 determines that the engine warm-up keeping condition is satisfied (YES in steps S28 and 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 the air flows in 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 upstream catalyst 31 can be concentrated and warmed up.

  Therefore, in the engine warm-up system 100 of the second embodiment, it is possible to warm up the engine 1 and the upstream catalyst 31 with emphasis. This makes it possible to finish the engine warm-up process more quickly.

(Modification)
FIG. 12 is a diagram showing a modification of the first embodiment. Description of the configuration substantially equivalent to that of the above-described engine warm-up system 100 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 heater 304, and a control device 310.

  The exhaust control valve 302 is provided downstream of a point where the EGR passage 33 in the exhaust passage 20 is connected, and on the upstream side of the downstream catalyst 32. The exhaust control valve 302 is in an open state during operation of the engine 1, and does not adjust the flow rate of air flowing from the upstream side of the exhaust control valve 302 in the exhaust flow passage 20, but downstream of the exhaust control valve 302. Pass it to the side. Further, the exhaust control valve 302 adjusts the flow rate of air discharged to the outside through the exhaust flow passage 20 by adjusting the opening degree during engine warm-up described later in detail.

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

  The control device 310 newly functions as the exhaust control valve control unit 312 and the heater control unit 314 in addition to the function of the control device 110 described above.

  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 passage 20 is not discharged to the downstream side (outside of the engine warm-up system 300) than 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 out of the engine warm-up system 100). Therefore, the engine 1 can be warmed up more effectively (more aggressively) and at an earlier time.

  The heater control unit 314 heats the 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 air compressed and heated by the electric supercharger 22 is lowered in temperature by passing through the inside of the engine 1. Thus, the air flowing through the exhaust flow passage 20 has a lower temperature than the air passing through the crankcase flow passage 29. Therefore, the heater 304 is provided in the exhaust flow path 20, and the temperature of the air to be recirculated is raised by warming the circulating air. By raising the temperature of the recirculating air, the air is compressed to a higher temperature when it is again compressed by the electric supercharger 22. Thus, the engine 1 can be warmed up more effectively (more aggressively) and earlier by warming and circulating the air to be recirculated.

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

  Although the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to such embodiments. It is obvious that those skilled in the art can conceive of various changes or modifications within the scope of the claims, and it is naturally understood that they are also within the technical scope of the present invention. Be done.

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

  In the above embodiment, the hydraulic chamber 8g is provided with the same width portion 8h and the reduced width portion 8j so that the movable member 42 does not block the oil circuit 8f. However, instead of providing the hydraulic chamber 8g with the reduced width portion 8j in which the length in the width direction is shortened, a funnel portion in which both the length in the height direction and the length in the movement direction are shortened may be provided. Alternatively, in the hydraulic pressure chamber 8g, a projection may be provided between the connecting portion with the oil circuit 8f and the movable member 42 so as to protrude into the hydraulic pressure chamber 8g. Alternatively, the elastic member 41 may be provided at the other end 8n of the hydraulic chamber 8g.

  In the above embodiment, the piston pin 40 is provided with two piston pin grooves 40h, and correspondingly, the piston 8 is provided with two oil circuits 8f. However, the piston pin groove 40 h provided in the piston pin 40 and the oil circuit 8 f provided in the piston 8 are not necessarily limited to two, and one or three or more oil circuits may be provided. At least one or more piston pin grooves 40 h and an oil circuit 8 f having the same number may be provided in the piston pin 40 and the piston 8.

  Further, in the above embodiment, the case where the hydraulic pressure chamber 8g is provided in the piston 8 at a position orthogonal to the piston pin 40 (moving direction in FIG. 5A and FIG. 5B) 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 system 100, 300 has the bypass flow passage 36 for bypassing the EGR cooler 34 in the EGR flow passage 33 has been described. However, the bypass flow path 36 is not an essential configuration.

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

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

  Further, in the above embodiment, the case where the crankcase valve mechanism 200 is configured by 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 of the downstream intake flow passage 18b with the crankcase flow passage 29. In this case, the crank valve switches the flow path so that the intake (air) flows to either the downstream side intake flow path 18b or the crankcase flow path 29, and the intake air flowing through the crankcase flow path 29 (air Adjust the flow rate of). Then, the valve control unit 116 controls the crank valve and, as described above, causes the air compressed and heated by the electric turbocharger 22 to flow through the crankcase passage 29.

  Further, in the above-described modification, the case where the engine warm-up system 300 is further provided with the exhaust control valve 302 and the heater 304 has been described. However, both the exhaust control valve 302 and the heater 304 may not be provided. 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 turbocharger 22 is driven in the region B. However, as long as 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 be adjusted by the diameter of the communication passage 39.

  In the above embodiment, when controlling the intake valve 12 and the exhaust valve 13 in the overlap state, the case where the engine 1 is stopped at a crank angle at which the intake valve 12 and the exhaust valve 13 overlap is described. However, for example, a variable valve timing system (VVT) may be used to move the intake valve 12 and the exhaust valve 13 to an overlap state when the engine 1 is stopped or after it is stopped. In that case, when controlling the opening and closing of each valve (step S36), the intake / exhaust valve control unit 114 controls 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 degree.

  The present invention is applicable to an engine warm-up system for warming up an engine.

DESCRIPTION OF SYMBOLS 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 path 40 piston pin 41 elastic member 42 movable member

Claims (6)

A communication passage for communicating the crown surface facing the combustion chamber with the back surface facing the crank chamber;
A movable member moving between an open position for opening the communication passage when the engine is stopped and a closed position for closing the communication passage when the engine is driven;
Engine piston with a. The movable member is
The engine piston according to claim 1, wherein the piston is moved from the open position to the closed position by oil pressure of engine oil. And a hydraulic chamber formed crossing the communication passage and supplied with the engine oil when the engine is driven.
The movable member is
The engine piston according to claim 2, housed in the hydraulic chamber. It comprises an elastic member provided in the hydraulic chamber and biasing the movable member in a direction from the closed position toward the open position.
The movable member is moved from the open position to the closed position against the biasing force of the elastic member by the hydraulic pressure of the engine oil when the engine is driven, and by the biasing force of the elastic member when the engine is stopped. The engine piston of claim 3, wherein the piston is moved from the closed position to the open position. An oil circuit that brings the hydraulic chamber into communication with a piston pin hole into which a piston pin is inserted;
Equipped with
The oil circuit is
The engine piston according to claim 3 or 4, wherein the engine oil is circulated in the hydraulic pressure chamber. A communication passage for communicating the crown surface facing the combustion chamber with the back surface facing the crank chamber;
A movable member that opens the communication passage when the engine is stopped and closes the communication passage when the engine is driven;
Engine piston with a.

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