JP2008002442A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of effectively reducing pumping loss over a whole rotation speed range. <P>SOLUTION: The internal combustion engine is provided with a plurality of cylinder bores in which a piston 2 can reciprocatingly move respectively, a plurality of combustion chambers 5 provided on one side in a movement direction of the piston 2 and having a suction port 6 and an exhaust port 7 connected thereto, a plurality of crank chambers 4 provided on another side in the movement direction of the piston 2, a crankshaft 10 provided with passing through the plurality of crank chambers 4 and rotatable with interlocking with reciprocating motion of the piston 2, a communication passage 20 establishing communication among the plurality of crank chambers 4 with openings 20a, an opening adjusting means 21 capable of adjusting opening of the communication passage 20, and a control means 22 controlling the communication passage 20 by the opening adjusting means 21 according to rotation speed of the crank shaft 10. Consequently, pumping loss can be effectively reduced over the whole rotation speed range. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine having a plurality of crank chambers.

  As an internal combustion engine mounted on a vehicle such as a passenger car or a truck, an internal combustion engine having a plurality of cylinders in which pistons can reciprocate, and a plurality of crank chambers corresponding to the cylinders are independently partitioned by a bulkhead. The institution is known. In such an internal combustion engine, during its operation, a pumping loss occurs due to pressure fluctuations in the crank chamber (including the internal space of the cylinder continuous with the crank chamber) that accompanies the reciprocating motion of the piston, and this is a resistance during operation of the internal combustion engine. It is one of. In recent years, demands for higher output and improved fuel efficiency of internal combustion engines have increased, and in order to meet these demands, it is important to reduce this pumping loss. Therefore, as a conventional internal combustion engine, by forming a communication hole in the bulkhead that defines each crank chamber, the air that is pressed toward the crank chamber as the piston descends, for example, the crank angle is adjacent to each other by 180 degrees. In some cases, the pressure generated in the crank chamber is released by releasing the pressure into the crank chamber, thereby relaxing the pressure fluctuation in the crank chamber and reducing the pumping loss.

  By the way, when the communication hole is provided in the bulkhead of the crank chamber as described above, this pumping loss becomes the maximum when the predetermined communication hole area is reached. This predetermined communication hole area is the rotational speed of the internal combustion engine. Depends on. In other words, the optimal communication hole area for reducing the pumping loss varies depending on the rotational speed of the internal combustion engine. Therefore, even if the optimal communication hole area is set for a certain rotational speed, it is effective over the entire rotational range. It has been difficult to reduce the pumping loss.

  In addition, as such an internal combustion engine, there exists an engine of patent document 1, for example. This engine includes a scavenging chamber common to each cylinder extending in the crankshaft direction, and this scavenging chamber communicates with each crank chamber by a scavenging adjustment opening. The scavenging adjustment opening can be opened and closed by a scavenging control valve provided inside (for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-238383

  However, the engine described in Patent Document 1 described above is a two-cycle diesel engine in which an intake manifold is connected to the crank chamber, and the air sucked into the crank chamber is introduced into the main combustion chamber for combustion. By changing the crank chamber volume by opening and closing the scavenging control valve, the scavenging air pressure is changed to vary the amount of intake air into the crank chamber. Loss cannot be reduced.

  Therefore, an object of the present invention is to provide an internal combustion engine that can effectively reduce the pumping loss over the entire rotation range.

  In order to achieve the above object, an internal combustion engine according to a first aspect of the present invention is provided with a plurality of cylinder bores, each of which is capable of reciprocating, and an intake port and an exhaust port in communication with each other. A plurality of combustion chambers, a plurality of crank chambers provided on the other side of the piston in the moving direction, and a crank that is provided through the plurality of crank chambers and is rotatable in conjunction with the reciprocating motion of the pistons A shaft, a communication passage communicating the plurality of crank chambers with openings, an opening adjustment means capable of adjusting an opening of the communication passage, and the communication by the opening adjustment means according to the rotational speed of the crankshaft. And a control means for controlling the opening of the passage.

  An internal combustion engine according to a second aspect of the invention includes a bore wall surface that forms the plurality of cylinder bores, and a cylinder block that has a crank chamber wall surface that is continuous with a lower end portion of the bore wall surface and forms the plurality of crank chambers, The opening of the communication path is provided at the lower end portion of the bore wall surface.

  An internal combustion engine according to a third aspect of the present invention is characterized in that the opening of the communication path faces the rotation direction of the crankshaft.

  In the internal combustion engine according to the invention according to claim 4, the control means controls the opening degree of the communication path by the opening degree adjusting means to be maximized when the rotational speed of the crankshaft is in a low speed range, When the rotational speed of the crankshaft is in a high speed range, control is performed so that the opening degree of the communication path by the opening degree adjusting means is minimized.

  In the internal combustion engine according to the fifth aspect of the invention, the maximum opening of the communication path by the opening adjusting means is set according to the strength of the wall surface on which the opening is formed, and the minimum opening is within the crank chamber. It is set according to the negative pressure.

  In the internal combustion engine according to a sixth aspect of the present invention, the opening degree adjusting means is formed in a cylindrical shape, and is provided with a rotary valve provided in the communication path so as to be rotatable in the circumferential direction and provided with a communication hole in the outer peripheral surface. And the opening area of the communication path can be changed by closing and opening the opening of the communication path through the outer peripheral surface and the communication hole.

  In the internal combustion engine according to a seventh aspect of the invention, the opening degree adjusting means includes a flapper valve having a base end portion fixed to the rotating shaft and a tip end portion rotatable along the inner surface of the communication path. The flapper valve can change the passage area in the opening of the communication passage by rotating with the rotation of the rotary shaft.

  In the internal combustion engine according to an eighth aspect of the present invention, the opening degree adjusting means has a slide valve that can move up and down over the opening of the communication path, and the slide valve moves up and down to move the opening of the communication path. The opening area of the opening can be changed.

  In the internal combustion engine according to the ninth aspect of the present invention, the opening degree adjusting means is fixed to the rotating shaft, the length from the rotating shaft to one end portion is different from the length to the other end portion, and the butterfly is bent at the fixed portion. It has a valve | bulb, The opening area can be changed by closing the opening of the said communicating path by the said one end part side or the said other end part side of this butterfly valve.

  According to the internal combustion engine of the present invention, the communication passage that communicates the plurality of crank chambers with openings, the opening adjustment means that can adjust the opening of the communication passage, and the opening adjustment means according to the rotational speed of the crankshaft. Therefore, the pumping loss can be effectively reduced over the entire rotation range.

  Embodiments of an internal combustion engine according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments. In addition, constituent elements in the following embodiments include those that can be easily replaced by those skilled in the art or those that are substantially the same.

  1 is a schematic cross-sectional view of an engine according to Embodiment 1 of the present invention, FIG. 2 is a side view of a cylinder block of the engine according to Embodiment 1 of the present invention, and FIG. 3 is Embodiment 1 of the present invention. FIG. 4 is a partial sectional view showing the maximum opening degree of the communication passage of the engine according to the first embodiment of the present invention, and FIG. 5 is a first embodiment of the present invention. FIG. 6 is a partial sectional view showing the minimum opening of the communication passage of the engine according to the first embodiment of the present invention, and FIG. 7 shows the main opening of the communication passage of the engine according to the first embodiment. FIG. 8 is a front view showing an opening at the minimum opening of a communication passage of an engine according to Embodiment 1 of the invention, and FIG. 8 is a line showing a relationship between the opening of the communication passage of the engine and pumping loss according to Embodiment 1 of the present invention. FIG.

  As shown in FIG. 1, an engine 1 as an internal combustion engine according to the first embodiment is an engine mounted on a vehicle such as a passenger car or a truck, and the piston 2 provided in the cylinder bore 3 so as to be capable of reciprocating is reciprocated twice. In addition, the engine is a so-called four-cycle engine that performs a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke.

  The engine 1 includes a plurality of cylinder bores 3 in which pistons 2 can reciprocate, a plurality of combustion chambers 5 provided on one side of the piston 2 in the moving direction, and a plurality of cylinders 3 provided on the other side of the piston 2 in the moving direction. A crank chamber 4 is provided. Here, the moving direction of the piston 2 is the axial direction of the cylinder bore 3 formed in a cylindrical shape. That is, the combustion chamber 5 is provided on one side in the axial direction of the cylinder bore 3 with the piston 2 in between, and the crank chamber 4 is provided on the other side. As shown in FIG. 2, the engine 1 is a four-cylinder engine having four crank chambers 4, combustion chambers 5, pistons 2 (see FIG. 1), and four cylinder bores 3 (see FIG. 1). However, the number of cylinders is an example and is not necessarily limited to four cylinders.

  Further, as shown in FIG. 1, the engine 1 includes an intake port 6 and an exhaust port 7 that communicate with the combustion chamber 5, an injector 8 that can directly inject fuel into the combustion chamber 5, A spark plug 9 is located above and ignites the air-fuel mixture, and a crankshaft 10 that can rotate in conjunction with the reciprocating motion of the piston. The engine 1 further includes a cylinder head 11, a cylinder block 12, and an oil pan 13.

  The cylinder head 11 is fastened on the cylinder block 12, and the oil pan 13 is fastened to the lower part of the cylinder block 12. The cylinder block 12 has a cylindrical cylinder bore 3 formed therein. The cylinder block 12 has a bore wall surface 3a that forms a plurality of cylinder bores 3 and a crank chamber wall surface 4a that forms a plurality of crank chambers 4. The bore wall surface 3a and the crank chamber wall surface 4a are formed on the bore wall surface 3a. It is continuous at the lower end 3b and the upper end 4b of the crank chamber wall surface 4a.

  The piston 2 is fitted to the cylinder bore 3 so as to be movable up and down. The plurality of crank chambers 4 communicate with the plurality of cylinder bores 3 respectively, and are further partitioned independently by a bulkhead 16 as a partition as shown in FIG. More specifically, each crank chamber 4 includes, as shown in FIG. 1, a bulkhead 16, a crank chamber wall surface 4a, an oil pan 13, and a bottom surface 2b which is one end surface of the piston 2. It is partitioned by the bore wall surface 3a. That is, the volume of each crank chamber 4 changes due to the reciprocating motion of the piston 2, and when the piston 2 is located on the top dead center side (cylinder head 11 side), the internal space of the cylinder bore 3 is also part of it. included. The oil pan 13 has a baffle plate 13a mounted therein and stores lubricating oil.

  The crankshaft 10 is provided so as to pass through the plurality of crank chambers 4 and the bulkhead 16, and each piston 2 is connected to the crankshaft 10 via a connecting rod 17. The crankshaft 10 has a counterweight 10a around its axis. The reciprocating motion of each piston 2 is transmitted to the crankshaft 10 via the connecting rod 17, where it is converted into rotational motion and taken out as the output of the engine 1. In this engine 1, the crankshaft 10 and the counterweight 10a rotate clockwise as indicated by arrows in FIG.

  The combustion chamber 5 is provided on the opposite side of the crank chamber 4 with the piston 2 in between. A plurality of combustion chambers 5 are formed corresponding to the plurality of cylinder bores 3, and are defined by the lower surface 11 a of the cylinder head 11, the bore wall surface 3 a of the cylinder bore 3, and the top surface 2 a which is the other end surface of the piston 2. Two intake ports 6 and two exhaust ports 7 are formed in the upper portion of the combustion chamber 5, that is, in the lower surface 11 a of the cylinder head 11. An intake valve 14 and an exhaust valve 15 are provided at the openings of the intake port 6 and the exhaust port 7. The intake valve 14 and the exhaust valve 15 can open and close the intake port 6 and the exhaust port 7, respectively, and can connect the intake port 6 and the combustion chamber 5, and the combustion chamber 5 and the exhaust port 7, respectively. The intake port 6 is connected to an intake passage (intake pipe) 18 that introduces air upstream in the intake direction, and the exhaust port 7 is provided with an exhaust passage (exhaust pipe) 19 that discharges exhaust gas downstream in the exhaust direction. Connected.

  The injector 8 is attached to the intake port 6 side of the cylinder head 11. In addition, the injector 8 is provided with a tip inclined toward the center line of the cylinder bore 3 by a predetermined angle with respect to the vertical direction. The injector 8 injects fuel spray toward the top surface 2 a of the piston 2. The spark plug 9 is attached to the ceiling portion of the combustion chamber 5, that is, between the intake port 6 and the exhaust port 7 on the lower surface 11 a of the cylinder head 11.

  In the engine 1, when the piston 2 descends in the cylinder bore 3, air is sucked into the combustion chamber 5 through the intake passage 18 and the intake port 6 (intake stroke). It mixes with the fuel injected into it to form an air-fuel mixture. The air-fuel mixture is compressed by the piston 2 ascending in the cylinder bore 3 through the intake stroke bottom dead center (compression stroke), and when the piston 2 approaches the vicinity of the compression stroke top dead center, the mixture is made into the air-fuel mixture by the spark plug 9. It is ignited, the air-fuel mixture burns, and the piston 2 is lowered by the combustion pressure (expansion stroke). The air-fuel mixture after combustion is released as exhaust gas through the exhaust port 7 and the exhaust passage 19 as the piston 2 rises again toward the top dead center of the intake stroke via the expansion stroke bottom dead center (exhaust stroke). . The reciprocating motion of the piston 2 in the cylinder bore 3 is transmitted to the crankshaft 10 via the connecting rod 17, where it is converted into a rotational motion and taken out as an output. As the shaft 10 further rotates due to the inertial force, the cylinder 10 reciprocates in the cylinder bore 3 as the crankshaft 10 rotates. By rotating the crankshaft 10 twice, the piston 2 reciprocates the cylinder bore 3 twice, and during this time, a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke are performed, and once in the combustion chamber 5. Explosion takes place.

  By the way, in such an engine 1, during its operation, a pumping loss occurs due to pressure fluctuation in each crank chamber 4 due to the reciprocating motion of the piston 2, and this is one of the resistances during operation of the engine. However, as shown in FIGS. 1 and 2, the engine 1 according to this embodiment includes a communication passage 20 that communicates a plurality of crank chambers 4 with openings 20 a, and an opening adjustment that can adjust the opening of the communication passage 20. As shown in FIG. 3, an opening degree adjusting unit 21 as means and an electronic control unit (hereinafter referred to as control means) for controlling the opening degree of the communication path 20 by the opening degree adjusting unit 21 according to the rotational speed of the crankshaft 10. (Referred to as “ECU”) 22 allows air that is pressed toward the crank chamber 4 side as the piston 2 moves to flow out to the crank chamber 4 having a low internal pressure through the communication passage 20, and is effective over the entire rotation range. The pumping loss is reduced.

  As shown in FIG. 1, the communication passage 20 has a shape in which the wall surface swells outside the portion where the lower end portion 3b of the bore wall surface 3a of the cylinder block 12 and the upper end portion 4b of the crank chamber wall surface 4a intersect and continue. Provided. The communication path 20 is provided substantially parallel to the crankshaft 10 along the longitudinal direction of the crankshaft 10, and an opening 20a for each crank chamber 4 is formed in the lower end portion 3b. As a result, each opening 20a of the communication passage 20 can be positioned in the vicinity of the bottom surface 2b at the bottom dead center position of the piston 2 where the pressure fluctuation is most likely to increase in each crank chamber 4. Here, the opening 20a of the communication passage 20 is formed so as to cover the lower end portion 3b of the bore wall surface 3a and the upper end portion 4b of the crank chamber wall surface 4a, and when the piston 2 is at the bottom dead center position, The opening 20 a is formed so as not to overlap the piston 2. That is, the opening 20a is not closed by the piston 2.

  Moreover, each opening 20a of the communicating path 20 is formed so as to face the rotation direction of the crankshaft 10 and the counterweight 10a. That is, each opening 20a of the communication path 20 is formed in the left crank chamber wall surface 4a with respect to the crankshaft 10 and the counterweight 10a that rotate clockwise in FIG. Thereby, even if the lubricating oil in the crank chamber 4 is scraped up by the connecting rod 17 or the counterweight 10a, each opening 20a of the communication passage 20 does not face the scraped-up lubricating oil, Lubricating oil does not easily enter the communication path 20 through the opening 20a.

  As shown in FIG. 2, the opening adjustment unit 21 is formed in a cylindrical shape, and is provided with a rotary valve 23 that is rotatably provided in the circumferential direction in the communication path 20, and a bearing 24 that rotatably supports the rotary valve 23. Have The bearing 24 supports both ends of the rotary valve 23. The rotary valve 23 is provided along the longitudinal direction of the communication path 20, and is rotationally driven by an opening adjustment drive unit 25 having a vacuum actuator 26.

  As shown in FIG. 3, the opening adjustment drive unit 25 includes the above-described vacuum actuator 26, a vacuum switching valve (hereinafter referred to as “VSV”) 27, and a vacuum tank 28. The vacuum actuator 26 includes a movable plate 26a that divides the internal space into two spaces, a positive pressure portion 26c and a negative pressure portion 26d, and a connecting rod 26b fixed to the movable plate 26a. The connecting rod 26 b connects the surface on the positive pressure part 26 c side of the movable plate 26 a and the end face edge 23 a of the rotary valve 23. Further, in the vacuum actuator 26, the atmosphere is introduced into the positive pressure part 26c, while the VSV 27 is connected to the negative pressure part 26d via a pipe. The VSV 27 is electrically connected to the ECU 22. The VSV 27 can inhale the atmosphere inside by receiving a control signal from the ECU 22. The VSV 27 is connected to the vacuum tank 28 through a pipe. The vacuum tank 28 is further connected to the intake manifold of the engine 1 so that the inside is maintained at a negative pressure.

  When the VSV 27 does not receive a control signal from the ECU 22, the opening adjustment drive unit 25 configured in this way is negative in the negative pressure unit 26d of the vacuum actuator 26, the VSV 27, the vacuum tank 28, and the piping connecting them. Maintained at pressure. During this time, the movable plate 26a is sucked toward the negative pressure portion 26d. Here, when the VSV 27 receives a control signal from the ECU 22, the atmosphere is sucked into the VSV 27, and the pressure difference between the positive pressure part 26c and the negative pressure part 26d of the vacuum actuator 26 becomes smaller. The movable plate 26a that has been sucked toward the negative pressure part 26d moves to the positive pressure part 26c side. That is, the movable plate 26a reciprocates in accordance with a change in pressure difference between the positive pressure part 26c and the negative pressure part 26d in the vacuum actuator 26. Since the end face edge 23a of the rotary valve 23 is connected to the movable plate 26a via the connecting rod 26b, the rotary valve 23 can be rotated in the circumferential direction in conjunction with the reciprocating motion of the movable plate 26a. The rotary valve 23 is biased by the return spring 25a in the direction of rotation (the clockwise direction in the figure) when the pressure difference between the positive pressure part 26c and the negative pressure part 26d becomes small with respect to the circumferential direction. ing. Thereby, the rotary valve 23 can rotate quickly when the pressure difference between the positive pressure part 26c and the negative pressure part 26d becomes small.

  As shown in FIGS. 4 and 5, the rotary valve 23 of the opening adjustment unit 21 is provided with a communication hole 30 on the outer peripheral surface 29. One communication hole 30 is provided corresponding to the plurality of openings 20 a of each crank chamber 4 of the communication passage 20. Each communication hole 30 is formed at a position that coincides with the position of each opening 20 a with respect to the axial direction of the rotary valve 23. Further, both the opening 20 a and each communication hole 30 are formed in an elliptical shape that is long in the axial direction of the rotary valve 23 and has substantially the same size.

  When the rotary valve 23 is rotated by the above-described opening adjustment drive unit 25, the opening adjustment unit 21 closes and opens the opening 20a of the communication path 20 by the outer peripheral surface 29 and the communication hole 30 to reduce the opening area. Thus, the opening degree of the communication passage 20 can be adjusted in synchronization with each crank chamber 4.

  That is, the opening degree adjusting unit 21 opens the entire opening 20a by overlapping the opening 20a of the communication passage 20 and the communication hole 30 of the rotary valve 23 at all portions. As a result, the amount of air that flows into the rotary valve 23 through the opening 20 a and the communication hole 30, that is, into the communication passage 20 and goes back and forth in each crank chamber 4 increases. On the other hand, as shown in FIGS. 6 and 7, the opening degree adjusting unit 21 is configured such that the opening 20 a of the communication passage 20 and the communication hole 30 of the rotary valve 23 partially overlap each other, so that the remaining of the opening 20 a is caused by the outer peripheral surface 29. Close the part. As a result, the opening area of the opening 20a is reduced, and the amount of air flowing into and out of each crank chamber 4 through the opening 20a and the communication hole 30 into the rotary valve 23, that is, into the communication passage 20, is small. Become.

  As shown in FIG. 3, the ECU 22 is configured around a microcomputer, and controls each part of the engine 1. The ECU 22 is electrically connected to the VSV 27 of the opening adjustment drive unit 25 and is connected to the crank angle sensor 31. Also electrically connected. The crank angle sensor 31 detects the crank angle of each cylinder. The crank angle sensor 31 transmits the detected crank angle to the ECU 22. The ECU 22 determines the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke in each cylinder based on the received crank angle, and the engine 1 of the engine 1. Calculate the number of revolutions (rpm). Here, in other words, the engine speed corresponds to the rotational speed of the crankshaft 10, and as the rotational speed of the crankshaft 10 increases, the rotational speed of the crankshaft 10 and the engine rotational speed also increase.

  When the plurality of crank chambers 4 are communicated with each other through the communication path 20 as described above, the pumping loss becomes maximum when the communication path 20 has a predetermined opening as shown in FIG. However, the opening degree of the communication path 20 at which the pumping loss is maximized varies depending on the rotational speed of the engine 1. That is, the optimal opening of the communication passage 20 for reducing the pumping loss differs depending on the rotational speed of the internal combustion engine, so that even if the optimal opening of the communication passage 20 for a certain rotational speed is set, There is a possibility that the pumping loss cannot be effectively reduced over the rotation range.

  Therefore, the ECU 22 transmits a control signal to the VSV 27 of the opening adjustment drive unit 25 according to the engine speed, and controls the opening of the communication path 20 by the opening adjustment unit 21. Specifically, as shown in FIG. 8, the ECU 22 controls the driving of the opening adjustment driving unit 25 when the engine speed is in a low rotation range, for example, 1000 rpm or less (including an idle state), As shown in FIGS. 4 and 5, control is performed so that the opening degree of the communication path 20 by the opening degree adjusting unit 21 is maximized. Furthermore, the ECU 22 controls the drive of the opening adjustment drive unit 25 when the engine speed is in a high rotation range, for example, 6000 rpm or more. As shown in FIGS. It controls so that the opening degree of the communicating path 20 becomes the minimum. Further, in this embodiment, the ECU 22 controls the driving of the opening adjustment drive unit 25 even when the engine speed is in the middle rotation range, for example, about 3000 rpm, and the communication path 20 of the communication path 20 by the opening adjustment unit 21 is controlled. Control so that the opening is minimized.

  That is, in this embodiment, the ECU 22 maximizes the opening degree of the communication path 20 when the engine speed is in the low rotation range, and sets the opening degree of the communication path 20 when the engine speed is other than the middle / high rotation range. Minimize. As a result, the pumping loss is more effectively reduced by maximizing the opening degree of the communication passage 20 when the engine speed is in the low rotation range than when the opening degree is minimized in the low rotation range. In addition, the pumping loss can be reduced by minimizing the opening degree of the communication passage 20 when the engine speed is in the middle / high speed range as compared with the case where the opening degree is maximized in the middle / high speed range. It can reduce more effectively.

  Here, as shown in FIG. 8, when the opening of the communication path 20 is theoretically zero, the pumping loss approaches each crank chamber 4 to be in a completely closed state as the system, and the piston 2 moves to the crank chamber. Since most of the energy for compressing the air in 4 returns to the piston 2, the pumping loss approaches zero as much as possible. By increasing the opening from here, the energy that goes out of the system of each crank chamber 4 increases, so that the pumping loss increases toward the maximum value. Further, by further increasing the opening degree, the energy itself that the piston 2 compresses the air in the crank chamber 4 is reduced, so that the pumping loss is reduced again.

  Here, the maximum opening degree of the communication path 20 by the opening degree adjusting unit 21 shown in FIGS. 4 and 5 is set according to the strength of the wall surface on which the opening 20a is formed. As described above, theoretically, the larger the opening degree of the communication path 20 is, the more the pumping loss is reduced. However, the strength of the wall surface of the cylinder block 12 that forms the opening 20a of the communication path 20 is actually increased. Therefore, the opening 20a cannot be made infinitely large. Further, by increasing the wall surface of the cylinder block 12 forming the opening 20a, the area ratio of the opening 20a to the wall surface can be reduced, and the strength of the wall surface can be ensured while increasing the opening area of the opening 20a. In this case, the cylinder block 12 itself is increased in size, and the inner diameter of the communication path 20 needs to be increased, so that the engine 1 is increased in size. Since the reduction rate of the pumping loss by increasing the opening area of the opening 20a is small as shown in FIG. 8, it is not possible to reduce the pumping loss to meet the increase in size of the engine 1. Therefore, it is preferable to set the maximum opening of the communication path 20 according to the strength of the wall surface on which the opening 20a is formed.

  On the other hand, the minimum opening of the communication passage 20 by the opening adjusting unit 21 shown in FIGS. 6 and 7 is set according to the negative pressure in the crank chamber 4. As described above, theoretically, when the opening degree of the communication passage 20 is set to 0, the pumping loss is also substantially 0. However, in reality, when each crank chamber 4 is completely closed as a system, The pressure fluctuation of the engine 1 becomes too large, causing problems in the durability of the engine 1 such as breakage of the crank oil seal and breakage of the baffle plate 13a. That is, there is a limit value for the minimum opening of the communication passage 20 that can be used substantially from the viewpoint of durability of the engine 1, and therefore this minimum opening depends on the negative pressure in the crank chamber 4. It is preferable to set.

  Here, the volume of the above-described communication path 20 may be a volume necessary for air to pass back and forth between the crank chambers 4, and a volume larger than that is not necessary. As described above, when the volume of the communication path 20 is too large when the ECU 22 changes the opening degree of the communication path 20 by the opening degree adjusting unit 21 according to the engine speed, the response becomes worse. Because it ends up.

  In the engine 1 configured as described above, when the piston 2 reciprocates the cylinder bore 3, when the piston 2 moves from the bottom dead center side to the top dead center direction, the volume of the crank chamber 4 increases with the movement. Along with this, the internal pressure of the crank chamber 4 decreases. Further, when the piston 2 moves from the top dead center side toward the bottom dead center side, the volume of the crank chamber 4 decreases with the movement, and accordingly, the internal pressure of each crank chamber 4 increases. The internal pressure of each crank chamber 4 changes as described above due to the reciprocating motion of the piston 2, and each crank chamber 4 is provided with a communication passage 20 that communicates with each crank chamber 4. Thus, when the internal pressure of each crank chamber 4 changes, the air in the crank chamber 4 moves through the communication path 20 from the crank chamber 4 side where the pressure is high to the crank chamber 4 side where the pressure is low. . That is, when a pressure difference occurs in the internal pressure between the crank chambers 4 communicating with each other via the communication passage 20, air flows in a direction in which the pressure difference is reduced according to the pressure difference, and the crank chamber 4 The pressure generated in is released and the pumping loss is reduced.

  Under the control of the ECU 22, when the engine speed is in the low rotation range, the opening degree adjusting unit 21 maximizes the opening degree of the communication path 20 and increases the amount of air traveling between the crank chambers 4. The pumping loss in the rotation range is more effectively reduced, and the air flowing back and forth between the crank chambers 4 is minimized by the opening adjustment unit 21 when the engine speed is in the middle / high rotation range. By reducing the amount, the pumping loss in the middle / high rotation range is more effectively reduced.

  According to the engine 1 according to the first embodiment of the present invention described above, the piston 2 is provided on each side of the plurality of cylinder bores 3 in which the piston 2 can reciprocate, the intake port 6 and the exhaust port. 7, a plurality of combustion chambers 5, a plurality of crank chambers 4 provided on the other side in the moving direction of the piston 2, and a plurality of crank chambers 4 are provided so as to be linked to the reciprocating motion of the piston 2. A rotatable crankshaft 10, a communication passage 20 that communicates the plurality of crank chambers 4 with openings 20a, an opening adjustment portion 21 that can adjust the opening of the communication passage 20, and the rotational speed of the crankshaft 10, that is, The ECU 22 controls the opening degree of the communication passage 20 by the opening degree adjusting unit 21 according to the rotational speed of the engine 1.

  Therefore, since the plurality of crank chambers 4 that are partitioned independently are communicated with each other by the communication passage 20, when a change occurs in the internal pressure of each crank chamber 4 due to the reciprocating movement of the piston 2, The air moves through the communication passage 20 from the crank chamber 4 side where the pressure is high to the crank chamber 4 side where the pressure is low, and releases the pressure generated in the crank chamber 4. Further, the opening degree of the communication path 20 is adjusted by the opening degree adjustment unit 21, and the opening degree of the communication path 20 by the opening degree adjustment unit 21 is controlled by the ECU 22 according to the rotational speed of the engine 1. The opening can be set to an optimum opening for reducing the pumping loss according to the rotation range of the engine 1, and the pumping loss having different characteristics according to the rotation range can be effectively reduced over the entire rotation range.

  Furthermore, according to the engine 1 according to the first embodiment of the present invention described above, the ECU 22 has the maximum opening of the communication path 20 by the opening adjustment unit 21 when the rotational speed of the engine 1 is in the low rotation range. When the rotational speed of the engine 1 is in the middle / high rotation range, the opening degree of the communication path 20 by the opening degree adjusting unit 21 is controlled to be minimum. Therefore, the ECU 22 maximizes the opening degree of the communication passage 20 when the engine speed is in the low rotation range, thereby increasing the amount of air traveling between the crank chambers 4 and reducing the opening degree in the low rotation range. The pumping loss is reduced more effectively than when it is minimized, and the opening and closing of the communication passage 20 is minimized when the engine speed is in the middle / high engine speed range, so that each crank chamber 4 is traversed. Since the pumping loss is more effectively reduced compared to the case where the amount of air is reduced and the opening degree is maximized in the middle / high rotation range, the pumping loss is reduced in both the low rotation range and the middle / high rotation range. Both reductions can be achieved and the total pumping loss can be greatly reduced.

  Furthermore, according to the engine 1 according to the first embodiment of the present invention described above, the maximum opening degree of the communication path 20 by the opening degree adjusting unit 21 is set according to the strength of the wall surface on which the opening 20a is formed. . Therefore, the strength of the wall surface on which the opening 20a is formed can be sufficiently ensured while ensuring the opening area of the opening 20a necessary for reducing the pumping loss without increasing the size of the cylinder block 12, and hence the engine 1. . Further, the minimum opening of the communication passage 20 by the opening adjusting unit 21 is set according to the negative pressure in the crank chamber 4. Therefore, the opening 20a can be made to have an opening area close to an ideal value for reducing the pumping loss without causing the pressure fluctuation in the crank chamber 4 to become too large and reducing the durability of the engine 1.

  Furthermore, according to the engine 1 according to the first embodiment of the present invention described above, the bore wall surface 3a forming the plurality of cylinder bores 3 and the lower end portion 3b of the bore wall surface 3a are connected to the plurality of crank chambers 4. The cylinder block 12 having the crank chamber wall surface 4a to be formed is provided, and the opening 20a of the communication passage 20 is provided in the lower end portion 3b of the bore wall surface 3a. Therefore, the communication passage 20 communicates with each crank chamber 4 through the opening 20a at a position where the pressure fluctuation is most likely to occur in each crank chamber 4, so that air can be efficiently transferred between the crank chambers 4 through the communication passage 20. The pressure difference between the crank chambers 4 via the communication passage 20 can be reduced more quickly without unnecessarily increasing the area of the opening 20a.

  Furthermore, according to the engine 1 according to the first embodiment of the present invention described above, the opening 20a of the communication path 20 faces the rotation direction of the crankshaft 10. Therefore, each opening 20a of the communication path 20 does not face the lubricating oil scraped up by the connecting rod 17 or the counterweight 10a, so that the lubricating oil enters the communication path 20 through each opening 20a. Therefore, it is possible to prevent the ECU 22 from being out of control because the opening degree of the communication passage 20 is substantially reduced.

  Furthermore, according to the engine 1 according to the first embodiment of the present invention described above, the opening degree adjusting unit 21 is formed in a cylindrical shape, is provided in the communication passage 20 so as to be rotatable in the circumferential direction, and has an outer peripheral surface 29. The rotary valve 23 is provided with a communication hole 30, and the rotary valve 23 rotates to close and open the opening 20 a of the communication path 20 by the outer peripheral surface 29 and the communication hole 30, thereby changing the opening area. Therefore, by rotating the rotary valve 23, the opening area of the opening 20a corresponding to each crank chamber 4 can be changed synchronously, and the opening 20a of the communication passage 20 and the communication hole 30 overlap in all portions. Thus, since the entire opening 20a is opened and the opening degree of the communication passage 20 is increased, the amount of air traveling between the crank chambers 4 can be increased, while the opening 20a of the communication passage 20 and the communication hole 30 Are partially overlapped, so that a part of the opening 20a is closed by the outer peripheral surface 29 and the opening degree of the communication passage 20 is reduced, so that the amount of air traveling between the crank chambers 4 can be reduced. In addition, for example, the position of the communication hole 30 is shifted in the circumferential direction according to each crank chamber 4, so that the timing of closing and opening of the opening 20 a is appropriately set by a slight change according to the characteristics of the engine 1. Can do.

  FIG. 9 is a partial cross-sectional view showing the maximum opening of the communication passage of the engine according to the second embodiment of the present invention, and FIG. 10 shows the opening at the maximum opening of the communication passage of the engine according to the second embodiment of the present invention. FIG. 11 is a partial cross-sectional view showing the minimum opening of the communication path of the engine according to the second embodiment of the present invention, and FIG. 12 shows the minimum of the communication path of the engine according to the second embodiment of the present invention. It is a front view which shows the opening at the time of an opening degree.

  The engine according to the second embodiment has substantially the same configuration as the engine according to the first embodiment, but differs from the engine according to the first embodiment in that the opening degree adjusting means includes a flapper valve instead of the rotary valve. In addition, about the structure, effect | action, and effect which are common in the Example mentioned above, while overlapping description is abbreviate | omitted as much as possible, the same code | symbol is attached | subjected.

  As shown in FIG. 9, in the engine 201 according to the second embodiment, the opening degree adjusting unit 221 serving as the opening degree adjusting unit is configured such that the base end 233 a is fixed to the rotating shaft 232 and the tip end 233 b is connected to the communication path 20. It has a plate-shaped flapper valve 233 that can rotate along the inner surface. Here, the cross section of the communication path 20 of the present embodiment is formed in a semicircular shape, and the communication path 20 is formed so that the curved surface of the semicircular cross section faces the outside of the cylinder block 12. The opening 20a of the communication path 20 is formed so that only one radius is opened in the straight portion of the semicircular cross section of the communication path 20. In the present embodiment, the opening 20a is formed in a rectangular shape.

  The rotation shaft 232 is provided along the longitudinal direction of the communication path 20 at a substantially central portion of the semicircular cross section of the communication path 20. Further, the rotary shaft 232 can be rotated in the circumferential direction by the opening adjustment drive unit 25 described with reference to FIG. 3 in substantially the same manner as the rotary valve 23 of the first embodiment. One flapper valve 233 is provided corresponding to the plurality of openings 20 a of each crank chamber 4, and is fixed to the rotating shaft 232. Thereby, the opening area of the opening 20a corresponding to each crank chamber 4 can be changed synchronously. And this flapper valve 233 can change the passage area in the opening 20a of the communication path 20 by rotating with rotation of the rotating shaft 232, and thereby the opening degree of the communication path 20 can be adjusted. It is.

  That is, as shown in FIGS. 9 and 10, the opening degree adjusting unit 221 maximizes the passage area in the opening 20 a of the communication passage 20 by the flapper valve 233 falling to the opposite side of the opening 20 a around the rotation shaft 232. To. As a result, the amount of air that flows into the communication passage 20 through the opening 20a and travels between the crank chambers 4 increases. On the other hand, as shown in FIGS. 11 and 12, the opening degree adjusting unit 221 is configured such that the rotating shaft 232 is rotated by the opening degree adjusting driving unit 25, and the tip end part 233 b of the flapper valve 233 is opened along the inner surface of the communication path 20. By rotating in the circumferential direction toward 20a, the passage area in the opening 20a of the communication passage 20 is reduced. As a result, the amount of air that flows into the communication passage 20 through the opening 20a and goes back and forth between the crank chambers 4 is reduced.

  According to the engine 201 according to the second embodiment of the present invention described above, the opening degree adjusting unit 221 has the base end portion 233a fixed to the rotating shaft 232 and the tip end portion 233b rotating along the inner surface of the communication path 20. A movable flapper valve 233 is provided, and the flapper valve 233 rotates with the rotation of the rotary shaft 232, whereby the passage area of the communication passage 20 can be changed. Accordingly, since the rotation shaft 232 rotates and the flapper valve 233 falls to the opposite side of the opening 20a around the rotation shaft 232, the passage area in the opening 20a of the communication passage 20 is increased. While the amount of air to be increased can be increased, the tip end portion 233b of the flapper valve 233 rotates along the inner surface of the communication path 20 in the circumferential direction toward the opening 20a, whereby the passage area of the communication path 20 at the opening 20a. Therefore, it is possible to reduce the amount of air going back and forth between the crank chambers 4. And, for example, compared with the opening degree adjusting unit 21 of the first embodiment in which the rotary valve 23 is used, the opening degree of the communication passage 20 is appropriately set with the opening degree adjusting unit 221 having a relatively simple structure. In addition, since it is not necessary to provide high accuracy for providing it at a predetermined position like the communication hole 30 described above, it is possible to reduce a portion that requires high processing accuracy. Furthermore, by using the opening degree adjusting unit 221 by the flapper valve 233, it is not necessary to make the passage section of the communication passage 20 circular as in the first embodiment, and a semicircular shape or the like according to the installation space of the communication passage 20 or the like. Therefore, the engine 201 can be further miniaturized and the degree of freedom in design can be improved.

  FIG. 13 is a partial cross-sectional view showing the maximum opening of the communication passage of the engine according to Embodiment 3 of the present invention, and FIG. 14 shows the opening at the maximum opening of the communication passage of the engine according to Embodiment 3 of the present invention. FIG. 15 is a partial cross-sectional view showing the minimum opening degree of the communication path of the engine according to the third embodiment of the present invention, and FIG. 16 shows the minimum of the communication path of the engine according to the third embodiment of the present invention. It is a front view which shows the opening at the time of an opening degree.

  The engine according to the third embodiment has substantially the same configuration as the engine according to the first embodiment, but differs from the engine according to the first embodiment in that the opening degree adjusting means includes a slide valve instead of the rotary valve. In addition, about the structure, effect | action, and effect which are common in the Example mentioned above, while overlapping description is abbreviate | omitted as much as possible, the same code | symbol is attached | subjected.

  As shown in FIG. 13, in the engine 301 according to the third embodiment, the opening adjustment unit 321 serving as the opening adjustment means has a plate-like slide valve 334 that can move up and down on the opening 20 a of the communication path 20. . Here, the passage cross section of the communication passage 20 of the present embodiment is formed in a semicircular shape as in the second embodiment, and the communication passage 20 is formed so that the curved surface of the semicircular cross section faces the outside of the cylinder block 12. Is done. The opening 20a of the communication path 20 is formed so that only one radius is opened in the straight portion of the semicircular cross section of the communication path 20. Furthermore, a slide surface member 336 that forms a slide surface with the slide valve 334 is provided in the remaining portion of the straight portion of the semicircular cross section. In the present embodiment, the opening 20a is formed in a rectangular shape.

  One slide valve 334 is provided corresponding to the plurality of openings 20a of each crank chamber 4, and is fixed to the drive shaft 335 on the surface opposite to the slide surface. Thereby, the opening area of the opening 20a corresponding to each crank chamber 4 can be changed synchronously. The drive shaft 335 is provided along the longitudinal direction of the communication path 20. Further, the end surface of the drive shaft 335 is connected to the connecting rod 26b of the opening adjustment drive unit 25 described with reference to FIG. 3, and the slide valve 334 can be moved up and down in conjunction with the reciprocating motion of the movable plate 26a. . The slide valve 334 can change the opening area of the opening 20a of the communication path 20 by moving up and down on the opening 20a of the communication path 20, and thereby the opening degree of the communication path 20 can be adjusted.

  That is, as shown in FIGS. 13 and 14, the opening degree adjusting unit 321 maximizes the opening area of the opening 20 a of the communication path 20 by moving the slide valve 334 up and down on the slide surface member 336. As a result, the amount of air that flows into the communication passage 20 through the opening 20a and travels between the crank chambers 4 increases. On the other hand, as shown in FIGS. 15 and 16, the opening adjustment unit 321 moves the drive shaft 335 by the opening adjustment drive unit 25 and moves the slide valve 334 up and down on the opening 20 a of the communication path 20. The opening area of the opening 20a is reduced. As a result, the amount of air that flows into the communication passage 20 through the opening 20a and goes back and forth between the crank chambers 4 is reduced.

  According to the engine 301 according to the third embodiment of the present invention described above, the opening degree adjusting unit 321 includes the slide valve 334 that can move up and down on the opening 20a of the communication path 20, and the slide valve 334 is moved up and down. By moving, the opening area of the opening 20a of the communication path 20 can be changed. Accordingly, since the slide valve 334 moves up and down on the slide surface member 336, the opening area of the opening 20a of the communication passage 20 is maximized, the amount of air traveling between the crank chambers 4 can be increased. Since the slide valve 334 moves up and down on the opening 20a of the communication passage 20 to reduce the opening area of the opening 20a, the amount of air traveling between the crank chambers 4 can be reduced. And, for example, compared with the opening degree adjusting unit 21 of the first embodiment that uses the rotary valve 23, the opening degree of the communication passage 20 is appropriately set with this opening degree adjusting unit 321 having a relatively simple structure. In addition, since it is not necessary to provide high accuracy for providing it at a predetermined position like the communication hole 30 described above, it is possible to reduce a portion that requires high processing accuracy. Furthermore, by using the opening degree adjusting unit 321 by the slide valve 334, the cross section of the communication path 20 does not need to be circular as in the first embodiment, and a semicircular shape or the like according to the installation space of the communication path 20 Therefore, the engine 301 can be further downsized and the degree of freedom in design can be improved. Further, unlike the flapper valve 233 of the second embodiment, the tip end portion 233b does not rotate along the inner surface of the communication passage 20, so that high dimensional accuracy of the slide valve 334 is not required, and the manufacturing efficiency is also improved in this respect. Can be improved.

  FIG. 17 is a partial cross-sectional view showing the maximum opening degree of the communication passage of the engine according to the fourth embodiment of the present invention, and FIG. 18 shows the opening at the maximum opening degree of the communication passage of the engine according to the fourth embodiment of the present invention. FIG. 19 is a partial cross-sectional view showing the minimum opening of the communication path of the engine according to the fourth embodiment of the present invention, and FIG. 20 shows the minimum of the communication path of the engine according to the fourth embodiment of the present invention. It is a front view which shows the opening at the time of an opening degree.

  The engine according to the fourth embodiment has substantially the same configuration as the engine according to the first embodiment, but is different from the engine according to the first embodiment in that the opening degree adjusting unit includes a butterfly valve instead of the rotary valve. In addition, about the structure, effect | action, and effect which are common in the Example mentioned above, while overlapping description is abbreviate | omitted as much as possible, the same code | symbol is attached | subjected.

  As shown in FIG. 17, in the engine 401 according to the fourth embodiment, the opening degree adjusting unit 421 as the opening degree adjusting means is fixed to the rotary shaft 440, and the cross-sectional shape is bent into a dogleg shape at this fixed portion. A butterfly valve 439 is provided. Here, the passage cross section of the communication passage 20 of the present embodiment is formed in a semicircular shape as in the second embodiment, and the communication passage 20 is formed so that the curved surface of the semicircular cross section faces the outside of the cylinder block 12. Is done. In the present embodiment, the opening 20a is formed in a rectangular shape.

  The rotating shaft 440 is provided along the longitudinal direction of the communication path 20 at a substantially central portion of the semicircular cross section of the communication path 20. Further, the rotation shaft 440 can be rotated in the circumferential direction by the opening adjustment drive unit 25 described with reference to FIG. 3 in substantially the same manner as the rotary valve 23 of the first embodiment. In the butterfly valve 439, the length from the rotation center of the rotary shaft 440 to the one end 437a and the length from the other end 438a are different. That is, the butterfly valve 439 includes a long side portion 437 having a relatively long length from the rotation center of the rotation shaft 440 to the end portion 437a, and a short side portion 438 having a relatively short length from the rotation center to the end portion 438a. Have One butterfly valve 439 is provided corresponding to the plurality of openings 20 a of each crank chamber 4, and is fixed to the rotating shaft 440. Thereby, the opening area of the opening 20a corresponding to each crank chamber 4 can be changed synchronously. The butterfly valve 439 rotates with the rotation of the rotation shaft 440, so that the long side 437 on the one end 437a side or the short side 438 on the other end 438a opens the opening 20a of the communication path 20. The opening area can be changed by closing, and thereby the opening degree of the communication path 20 can be adjusted.

  That is, as shown in FIGS. 17 and 18, the opening adjustment portion 421 is configured such that the short side portion 438 of the butterfly valve 439 falls toward the opening 20 a around the rotation shaft 440 and closes a part of the opening 20 a. By opening the remaining part, the opening area of the opening 20a is maximized. As a result, the amount of air that flows into the communication passage 20 through the opening 20a and travels between the crank chambers 4 increases. On the other hand, as shown in FIGS. 19 and 20, the opening degree adjusting unit 421 is configured such that the rotating shaft 440 is rotated by the opening degree adjusting driving unit 25, and the long side portion 437 of the butterfly valve 439 is opened around the rotating shaft 440. The opening area of the opening 20a is reduced by opening the portion where the short side portion 438 is closed and closing the remaining portion. As a result, the amount of air that flows into the communication passage 20 through the opening 20a and goes back and forth between the crank chambers 4 is reduced. The butterfly valve 439 is provided so that the long side portion 437 and the short side portion 438 are always located in the communication path 20, and the long side portion 437 and the short side are also rotated when being rotated by the opening adjustment drive unit 25. The portion 438 is prevented from protruding from the opening 20a to the crank chamber 4 side. Thereby, the clearance from the track | orbit of the connecting rod 17 and the counterweight 10a rotating in the crank chamber 4 to the opening 20a can be made small, and the engine 401 can be reduced in size.

  According to the engine 401 according to the fourth embodiment of the present invention described above, the opening degree adjusting unit 421 is fixed to the rotating shaft 440, and the length from the rotating shaft 440 to the one end 437a and the other end 438a. The butterfly valve 439 has a different length and is bent at a fixed portion, and the opening 20a of the communication path 20 is formed by the long side 437 on the one end 437a side or the short side 438 on the other end 438a side of the butterfly valve 439. The opening area can be changed by closing. Accordingly, the rotating shaft 440 rotates, the short side portion 438 of the butterfly valve 439 falls toward the opening 20a around the rotating shaft 440, and a part of the opening 20a is closed by the short side portion 438, whereby the opening 20a Therefore, the amount of air traveling back and forth in each crank chamber 4 can be increased, while the long side portion 437 falls toward the opening 20a around the rotation shaft 440, and the short side portion 438 By opening the closed part and closing the remaining part, the opening area of the opening 20a is reduced, so that the amount of air traveling between the crank chambers 4 can be reduced. And, for example, compared with the opening degree adjusting part 21 of the first embodiment that uses the rotary valve 23, the opening degree of the communication path 20 is appropriately set with this opening degree adjusting part 421 having a relatively simple structure. In addition, since it is not necessary to provide high accuracy for providing it at a predetermined position like the communication hole 30 described above, it is possible to reduce a portion that requires high processing accuracy. Furthermore, by using the opening degree adjustment part 421 by the butterfly valve 439, it is not necessary to make the cross section of the communication path 20 circular as in the first embodiment, and a semicircular shape or the like according to the installation space of the communication path 20 Therefore, the engine 401 can be further downsized and the degree of freedom in design can be improved.

  Further, when the clearance from the track of the connecting rod 17 and the counterweight 10a rotating in the crank chamber 4 to the opening 20a is sufficiently secured, the butterfly valve 439 is connected to the short side portion 438 (or the long side portion 437). ) Can be rotated until it comes out to the crank chamber 4 side. In this case, as shown by a broken line in FIG. 17, the butterfly valve 439 is rotated until the short side portion 438 comes out to the crank chamber 4 side to open the entire surface of the opening 20 a, so that the maximum opening is achieved according to the characteristics of the engine 401. The degree can be further increased. Furthermore, in this case, since the length from the rotation center of the rotating shaft 440 to the end portion 437a in the long side portion 437 can be further shortened, the passage cross section of the communication passage 20 can be made flatter, and the communication can be made. Since the protrusion of the passage 20 to the outside of the cylinder block 12 can be further reduced, the engine 401 can be further downsized.

  The engine according to the embodiment of the present invention described above is not limited to the embodiment described above, and various modifications can be made within the scope described in the claims. In the above description, the engines 1, 201, 301, and 401 have been described as direct injection engines, but may be port injection engines. In the above description, the opening adjustment drive unit 25 has been described as having the vacuum actuator 26 and the like and mechanically driving the opening adjustment units 21, 221, 321, and 421. May be driven. In the above description, the opening 20a has been described as being formed in an elliptical shape or a rectangular shape, but may be formed in other shapes.

  In the above description, the opening 20a of the communication passage 20 communicating with each crank chamber 4 is described as being formed so as to cover the lower end portion 3b of the bore wall surface 3a and the upper end portion 4b of the crank chamber wall surface 4a. Not limited to this. Further, the opening 20a does not have to face the rotation direction of the crankshaft 10. Further, in the above description, the ECU 22 maximizes the opening degree of the communication path 20 when the engine speed is in the low rotation range, and sets the opening degree of the communication path 20 when it is in the other medium / high rotation range. Although described as a minimum, according to the characteristics of the communication passage opening-pumping loss graph of the engine to which the present invention is applied, for example, the opening of the communication passage 20 is maximized in the middle rotation range. May be. In the above description, the opening degree of the communication path 20 has been described as using two stages of the maximum opening degree and the minimum opening degree. The opening degree may be adjusted linearly. Further, the communication path 20 may be provided so as to penetrate the bulkhead 16. Further, the opening degree adjustment units 21, 221, 321, 421 may individually adjust the opening degree of the communication passage 20 corresponding to each crank chamber 4.

  As described above, the internal combustion engine according to the present invention communicates the crank chambers with the communication passages, and effectively adjusts the opening degree of the communication passages according to the engine speed, thereby effectively reducing the pumping loss over the entire rotation range. This is suitable for a so-called four-cycle internal combustion engine that performs a series of four strokes consisting of an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke while the piston reciprocates twice.

It is typical sectional drawing of the engine which concerns on Example 1 of this invention. It is a side view of the cylinder block of the engine which concerns on Example 1 of this invention. It is a schematic diagram which shows the opening degree adjustment drive part of the engine which concerns on Example 1 of this invention. It is a fragmentary sectional view which shows the time of the maximum opening degree of the communicating path of the engine which concerns on Example 1 of this invention. It is a front view which shows opening at the time of the maximum opening degree of the communicating path of the engine which concerns on Example 1 of this invention. It is a fragmentary sectional view which shows the time of the minimum opening degree of the communicating path of the engine which concerns on Example 1 of this invention. It is a front view which shows the opening at the time of the minimum opening degree of the communicating path of the engine which concerns on Example 1 of this invention. It is a diagram which shows the relationship between the communicating path opening degree of an engine which concerns on Example 1 of this invention, and a pumping loss. It is a fragmentary sectional view which shows the time of the maximum opening degree of the communicating path of the engine which concerns on Example 2 of this invention. It is a front view which shows the opening at the time of the maximum opening degree of the communicating path of the engine which concerns on Example 2 of this invention. It is a fragmentary sectional view which shows the time of the minimum opening degree of the communicating path of the engine which concerns on Example 2 of this invention. It is a front view which shows the opening at the time of the minimum opening degree of the communicating path of the engine which concerns on Example 2 of this invention. It is a fragmentary sectional view which shows the time of the maximum opening degree of the communicating path of the engine which concerns on Example 3 of this invention. It is a front view which shows the opening at the time of the maximum opening degree of the communicating path of the engine which concerns on Example 3 of this invention. It is a fragmentary sectional view which shows the time of the minimum opening degree of the communicating path of the engine which concerns on Example 3 of this invention. It is a front view which shows the opening at the time of the minimum opening degree of the communicating path of the engine which concerns on Example 3 of this invention. It is a fragmentary sectional view which shows the time of the maximum opening degree of the communicating path of the engine which concerns on Example 4 of this invention. It is a front view which shows the opening at the time of the maximum opening degree of the communicating path of the engine which concerns on Example 4 of this invention. It is a fragmentary sectional view which shows the time of the minimum opening degree of the communicating path of the engine which concerns on Example 4 of this invention. It is a front view which shows the opening at the time of the minimum opening degree of the communicating path of the engine which concerns on Example 4 of this invention.

Explanation of symbols

1, 201, 301, 401 Engine 2 Piston 3 Cylinder bore 3a Bore wall surface 3b Lower end portion 4 Crank chamber 4a Crank chamber wall surface 4b Upper end portion 5 Combustion chamber 6 Intake port 7 Exhaust port 8 Injector 9 Spark plug 10 Crankshaft 11 Cylinder head 12 Cylinder Block 16 Bulkhead 20 Communication path 20a Openings 21, 221, 321, 421 Opening adjustment unit (opening adjustment means)
22 ECU (control means)
23 Rotary valve 25 Opening adjustment drive portion 29 Outer peripheral surface 30 Communication hole 232 Rotating shaft 233 Flapper valve 233a Base end portion 233b Tip end portion 334 Slide valve 335 Drive shaft 437a, 438a End portion 437 Long side portion 438 Short side portion 439 Butterfly valve 440 rotation axis

Claims (9)

A plurality of cylinder bores each capable of reciprocating pistons;
A plurality of combustion chambers provided on one side of the moving direction of the piston and communicating with an intake port and an exhaust port;
A plurality of crank chambers provided on the other side of the moving direction of the piston;
A crankshaft provided through the plurality of crank chambers and rotatable in conjunction with reciprocation of the piston;
A communication passage communicating the plurality of crank chambers with openings;
Opening degree adjusting means capable of adjusting the opening degree of the communication path;
Control means for controlling the opening degree of the communication path by the opening degree adjusting means according to the rotational speed of the crankshaft,
Internal combustion engine. A bore wall surface forming the plurality of cylinder bores, and a cylinder block having a crank chamber wall surface continuous with a lower end portion of the bore wall surface and forming the plurality of crank chambers,
The opening of the communication path is provided in the lower end portion of the bore wall surface,
The internal combustion engine according to claim 1. The opening of the communication path is directed to the rotation direction of the crankshaft,
The internal combustion engine according to claim 1 or 2. The control means controls the opening degree of the communication path by the opening degree adjusting means to be maximized when the rotation speed of the crankshaft is in a low speed range, and the rotation speed of the crankshaft is in a high speed range. Sometimes it is controlled so that the opening degree of the communication path by the opening degree adjusting means is minimized,
The internal combustion engine according to any one of claims 1 to 3. The maximum opening of the communication path by the opening adjustment means is set according to the strength of the wall surface on which the opening is formed, and the minimum opening is set according to the negative pressure in the crank chamber. And
The internal combustion engine according to claim 4. The opening adjusting means has a rotary valve formed in a cylindrical shape and provided rotatably in the circumferential direction in the communication path and provided with a communication hole in the outer peripheral surface. The opening area can be changed by closing and opening the opening of the communication path by an outer peripheral surface and the communication hole,
The internal combustion engine according to any one of claims 1 to 5. The opening degree adjusting means includes a flapper valve having a base end portion fixed to a rotation shaft and a tip end portion rotatable along the inner surface of the communication path, and the flapper valve is rotated along with the rotation of the rotation shaft. It is possible to change the passage area in the opening of the communication passage by rotating,
The internal combustion engine according to any one of claims 1 to 5. The opening degree adjusting means has a slide valve that can move up and down on the opening of the communication path, and the opening area of the opening of the communication path can be changed by the vertical movement of the slide valve. Characterized by the
The internal combustion engine according to any one of claims 1 to 5. The opening degree adjusting means includes a butterfly valve fixed to a rotating shaft, having a different length from the rotating shaft to one end and a length from the other end and being bent at the fixed portion, and the one end of the butterfly valve The opening area can be changed by closing the opening of the communication path on the part side or the other end side,
The internal combustion engine according to any one of claims 1 to 5.

Images