JP2006300011A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine by which combustion-time loss can be reduced, while reducing the cooling loss throughout from low to high rotation. <P>SOLUTION: In the expansion stroke in the internal combustion engine, the working distance of a piston with respect to a rotational angle of a crankshaft is changed in accordance with a rotational speed of the crankshaft. Since the working distance of the piston with respect to a rotational angle of the crankshaft in an expansion stroke is changed in accordance with the rotational speed of the crankshaft, combustion-time loss can be reduced, while reducing the cooling loss throughout from low to high rotation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an internal combustion engine.

In Patent Document 1, in order to enhance the intake inertia effect when the engine is operating at a low speed, the intake stroke and the expansion stroke are made faster than before by using a link mechanism, and the compression stroke and the exhaust stroke are made faster than before. A longer internal combustion engine is disclosed.
JP 2003-83102 A

  However, in Patent Document 1, when the engine is operating at a low rotation speed, there is a problem that the cooling loss increases and the net efficiency decreases because the time during which the combustion gas contacts the cylinder wall surface becomes long.

  In addition, since the piston motion in the intake stroke and the expansion stroke is substantially constant regardless of the engine speed, when the engine speed is high, the piston is greatly lowered during the combustion period, resulting in a large combustion time loss, that is, combustion. Therefore, there is a problem that the piston is lowered before the in-cylinder pressure is sufficiently increased, and a sufficient combustion pressure cannot be transmitted to the piston.

  Furthermore, since the intake stroke and the expansion stroke are the same piston motion, there is a possibility that the engine control is made suitable only for the intake stroke, and the engine cannot be used efficiently. Further, since the piston descends before the in-cylinder pressure sufficiently rises, there is a problem that the combustion time loss increases.

  Therefore, the internal combustion engine of the present invention is characterized in that the piston operating distance with respect to the rotation angle of the crankshaft is changed in accordance with the rotation speed of the crankshaft in the expansion stroke.

  According to the present invention, since the piston working distance with respect to the rotation angle of the crankshaft in the expansion stroke is changed according to the rotation speed of the crankshaft, the combustion time is reduced while reducing the cooling loss from the low rotation to the high rotation. Loss can be reduced.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  1 and 2 are explanatory views schematically showing a main body 1 (hereinafter referred to as an engine main body 1) of an internal combustion engine in a first embodiment of the present invention.

  The engine body 1 includes an intake compression cylinder 2 that performs an intake stroke and a compression stroke, and an expansion exhaust cylinder 3 that performs an expansion stroke and an exhaust stroke, and the intake compression cylinder 2 and the expansion exhaust cylinder 3 are substantially paired. One cylinder is constructed.

  An intake port 4 in which a fuel injection valve (not shown) is disposed is connected to the intake compression cylinder 2, and an air-fuel mixture is introduced into the intake compression cylinder 2 from the intake port 4 by opening the intake valve 5. Is introduced.

  The intake / compression cylinder 2 is connected to a pair of adjacent expansion and exhaust cylinders 3 via a connecting passage 6. A compression valve 7 is disposed at one end of the connection passage 6, that is, at a connection portion between the intake compression cylinder 2 and the connection passage 6.

  An exhaust port 8 is connected to the expansion exhaust cylinder 3, and exhaust is discharged from the expansion exhaust cylinder 3 by opening the exhaust valve 9.

  An intake compression piston 10 is disposed in the intake compression cylinder 2. The intake compression piston 10 is rotatably connected to a crankpin 12a of a crankshaft 12 that transmits combustion pressure as rotational power via an intake compression connecting rod 11.

  An expansion exhaust piston 14 that is rotatably connected to one end of an expansion exhaust connecting rod 13 is disposed in the expansion exhaust cylinder 3. The expansion / exhaust connecting rod 13 has a cam roller 15 at the other end, and the cam roller 15 is rotatably in contact with a three-dimensional cam 16 mounted on the crank journal 12b of the crankshaft 12. Note that reference numeral 17 in FIG. 1 denotes a spark plug.

  An expansion speed control actuator 18 is disposed at one end of the crankshaft 12. The expansion speed control actuator 18 moves the crankshaft 12 along the longitudinal direction of the crankshaft 12 (the direction perpendicular to the paper surface in FIG. 1 and the left-right direction in FIG. 2) according to the engine speed (number of rotations of the crankshaft 12). Slide. The expansion speed control actuator 18 may be electric or hydraulically driven.

  The three-dimensional cam 16 rotates integrally with the crank journal 12b. A plurality of three-dimensional cams 16 are arranged along the longitudinal direction of the crankshaft 12 as shown in FIG. The cam profile is formed continuously. More specifically, the three-dimensional cam 16 in the present embodiment is formed by continuously forming four cam profiles corresponding to the engine rotational speed, and the one positioned on the other end side of the crankshaft 12 has a lower rotation speed. It is a cam profile for. In addition, between each cam profile is formed in the taper shape, and when the crankshaft 12 is slid to the axial direction, the cam roller 15 of the expansion / exhaust exhaust connecting rod 13 is configured to smoothly follow. In addition, the three-dimensional cam 16 in the present embodiment changes the cam profile in four stages, but can be configured such that the cam profile can be changed steplessly by sliding the crankshaft 12. .

  In the internal combustion engine of the first embodiment, the intake stroke and the compression stroke performed in the intake compression cylinder 2 are performed by one rotation of the crankshaft 12. At the end of the compression stroke, the compression valve 7 is opened, and the compressed air-fuel mixture is introduced into the expansion exhaust cylinder 3. The expansion stroke and the exhaust stroke performed in the expansion / exhaust cylinder 3 are performed by one rotation of the crankshaft 12 as shown in FIG. Since the end of the compression stroke and the end of the exhaust stroke are executed in synchronization, the overall four strokes of intake, compression, expansion, and exhaust are completed with one revolution of the crankshaft 12. FIG. 4 shows an example of a cam profile selected when the engine speed is low.

  FIG. 5 is a timing chart showing the operation of each piston 10, 14 and each valve 5, 7, 9 of the internal combustion engine in the first embodiment.

  The intake valve 5 is opened in accordance with the operation of lowering the intake compression piston 10. When the intake compression piston 10 reaches the bottom dead center and starts to rise again, the intake valve 5 is closed. When the intake compression piston 10 approaches top dead center, the compression valve 7 is opened, and the compressed air-fuel mixture is sent to the expansion / exhaust cylinder 3. When the intake compression piston 10 reaches the top dead center, the compression valve 7 is closed to prevent the compressed air-fuel mixture from flowing backward. The compressed air-fuel mixture is ignited by the spark plug 17 and burned, and the expansion exhaust piston 14 is lowered. At this time, the expansion speed (lowering speed) and the in-cylinder pressure of the expansion / exhaust piston 14 are changed by the profile of the three-dimensional cam 16. When the expansion exhaust piston 14 starts to rise again from the bottom dead center, the exhaust valve 9 is opened and exhausted.

  The opening / closing timing of the intake valve 5 and the opening / closing timing of the exhaust valve 8 are preferably optimized according to the engine speed. Further, a torque amplifier and a torque interrupter may be arranged between the expansion speed control actuator 18 and the crankshaft 12. In the present embodiment, the combustion chamber is set in the expansion / exhaust cylinder 3. However, the combustion chamber may be provided between the intake / compression cylinder 2 and the expansion / exhaust cylinder 3, that is, in the connecting passage 6. .

  As described above, the internal combustion engine in the first embodiment is separated from the cylinder that performs the intake compression stroke and the cylinder that performs the expansion / exhaust stroke, and the expansion speed of the expansion / exhaust piston 14 in the expansion stroke and the inside of the expansion / exhaust cylinder 3 in the expansion stroke. The in-cylinder pressure can be changed and operated by the three-dimensional cam 16.

  6 and 7 are explanatory views schematically showing a main body 31 (hereinafter referred to as the engine main body 31) of the internal combustion engine in the second embodiment of the present invention.

  The engine body 31 includes an intake compression cylinder 32 that performs an intake stroke and a compression stroke, and an expansion exhaust cylinder 33 that performs an expansion stroke and an exhaust stroke, and the intake compression cylinder 32 and the expansion exhaust cylinder 33 are substantially paired. One cylinder is constructed.

  An intake port 34 in which a fuel injection valve (not shown) is disposed is connected to the intake compression cylinder 32, and an air-fuel mixture is supplied to the intake compression cylinder 32 from the intake port 34 by opening the intake valve 35. be introduced.

  The intake and compression cylinder 32 is connected to a pair of adjacent expansion and exhaust cylinders 33 via a connecting passage 36. A compression valve 37 is disposed at one end of the connection passage 36, that is, at a connection portion between the intake compression cylinder 32 and the connection passage 36.

  An exhaust port 38 is connected to the expansion exhaust cylinder 33, and exhaust is discharged from the expansion exhaust cylinder 33 by opening the exhaust valve 39.

  An intake compression piston 40 is disposed in the intake compression cylinder 32. The intake compression piston 40 is rotatably connected to a crank pin (not shown) of the crankshaft 42 via an intake compression connecting rod 41. The crankshaft 42 is connected to a transmission shaft (not shown), and an intake compression first speed gear 45 and an intake compression second speed gear 46 are arranged on one end side. The intake compression first speed gear 45 and the intake compression second speed gear 46 are fixed to the crank journal 42b of the crankshaft 42, and rotate integrally with the crank journal 42b of the crankshaft 42. In addition, 47 in FIG. 6 is a spark plug.

  An expansion exhaust piston 44 is disposed in the expansion exhaust cylinder 33. The expansion exhaust piston 44 is rotatably connected to the crank pin 52 a of the auxiliary crankshaft 52 via the expansion exhaust connecting rod 43. As shown in FIG. 8, the auxiliary crankshaft 52 is arranged in parallel with the crankshaft 42, and has an expansion exhaust first speed gear 48 that engages with the intake compression first speed gear 45 on one end side, An expansion exhaust second speed gear 49 that engages with the compression second speed gear 46 is disposed. The expansion exhaust first speed gear 48 is attached to the crank journal 52 b of the auxiliary crankshaft 52 via the first clutch 50. The expansion / exhaust second gear 49 is attached to the crank journal 52 b of the auxiliary crankshaft 52 via the second clutch 51.

  In the second embodiment, the intake compression first speed gear 45 and the expansion / exhaust first speed gear 48 are set such that the auxiliary crankshaft 52 has a rotational speed twice that of the crankshaft 42. The intake / compression second gear 46 and the expansion / exhaust second gear 49 are set such that the auxiliary crankshaft 52 has the same rotational speed as the crankshaft 42.

  The first clutch 50 is interposed between the expansion exhaust first speed gear 48 and the auxiliary crankshaft 52. The first clutch 50 engages and releases the expansion exhaust first speed gear 48 and the auxiliary crankshaft 52, and is engaged. Sometimes both can rotate integrally, and at the time of release, the expansion exhaust first speed gear 48 is separated from the auxiliary crankshaft 52, and no power is transmitted between the expansion exhaust first speed gear 48 and the auxiliary crankshaft 52. It is like that. The second clutch 51 is interposed between the expansion exhaust second speed gear 49 and the auxiliary crankshaft 52, and engages and releases the expansion exhaust second speed gear 49 and the auxiliary crankshaft 52 to be engaged. Sometimes both of them can rotate together, and at the time of release, the expansion / exhaust second gear 49 is separated from the auxiliary crankshaft 52, and no power is transmitted between the expansion / exhaust second gear 49 and the auxiliary crankshaft 52. It is like that. Here, when one of the first clutch 50 and the second clutch 51 is engaged, the other is released. Specifically, the first clutch 50 and the second clutch 51 are preferably a wet multi-plate clutch or a dog clutch having a sync mechanism. In the second embodiment, the auxiliary crankshaft 52 is switched in two steps so that the rotational speed of the auxiliary crankshaft 52 is the same as or twice the rotational speed of the crankshaft 42 according to the engine rotational speed. The gears (intake / compression first gear 45, expansion / exhaust / exhaust first gear 48, intake / compression / second gear 46, expansion / exhaust 2) so that the number of revolutions of 52 can be switched to two or more stages (multi-stage) according to the engine speed. A configuration in which the number of the speed gears 49) is increased is also possible.

  9 and 10 are timing charts showing the operations of the pistons 40, 44 and the valves 35, 37, 39 of the internal combustion engine according to the second embodiment, and FIG. 9 shows a low engine speed (the crankshaft 42). FIG. 10 is a timing chart when the engine speed is high (the crankshaft 42 is high).

  The intake valve 35 is opened in accordance with the operation of lowering the intake compression piston 40. When the intake compression piston 40 reaches the bottom dead center and starts to rise again, the intake valve 35 is closed. When the intake compression piston 40 approaches top dead center, the compression valve 37 is opened, and the compressed air-fuel mixture is sent to the expansion / exhaust cylinder 33. When the intake compression piston 40 reaches top dead center, the compression valve 37 is closed to prevent the backflow of the compressed air-fuel mixture. The compressed air-fuel mixture is ignited by the spark plug 47 and burned, and the expansion exhaust piston 44 is lowered.

  At this time, when the rotation speed of the crankshaft 42 is low, the auxiliary crankshaft 52 has a rotation speed twice that of the crankshaft 42 (first clutch: engaged, second clutch: release), and the rotation speed of the crankshaft 42 Is high, the rotation speed is controlled to be the same as that of the crankshaft 42 (first clutch: released, second clutch: engaged).

  The expansion speed of the expansion exhaust piston 44 is determined by which of the first clutch 50 and the second clutch 51 is engaged. Also, either the first clutch 50 or the second clutch 51 is fastened so that the intake / compression piston 40 and the expansion / exhaust piston 44 are simultaneously at the top dead center. When the expansion exhaust piston 44 starts to rise again from the bottom dead center, the exhaust valve 39 is opened and exhausted. When the engine speed is low, the first clutch 50 is engaged (the second clutch 51 is disengaged), and the expansion / exhaust piston 44 operates at a cycle twice that of the intake / compression piston 40. At this time, the first clutch 50 is engaged between the top dead center and the bottom dead center when the intake compression piston 40 is lifted from the bottom dead center so that no loss occurs.

  The opening / closing timing of the intake valve 35 and the opening / closing timing of the exhaust valve 39 are preferably optimized according to the engine speed. Further, it is preferable that the first clutch 50 in the engaged state is released when the expansion stroke is completed. Further, the first clutch 50 may be engaged, and the exhaust valve 39 may be opened until the intake compression piston 40 is at top dead center or before the compression valve 37 is opened. When the engine speed is high, the second clutch 51 is preferably engaged regardless of the stroke.

  Thus, the internal combustion engine in the second embodiment separates the cylinder that performs the intake compression stroke and the cylinder that performs the expansion / exhaust stroke, and the expansion speed of the expansion / exhaust piston 44 in the expansion stroke and the expansion / exhaust cylinder 33 in the expansion stroke. The internal cylinder pressure can be changed and operated by gear stages (intake compression first speed gear 45, expansion exhaust first speed gear 48, intake compression second speed gear 46, expansion exhaust second speed gear 49). .

  FIG. 11 is an explanatory view schematically showing an example of an engine system configuration common to the internal combustion engines of the first and second embodiments of the present invention described above.

  The engine system includes an air cleaner 61 for removing dust contained in fresh air, a throttle 62 for adjusting the intake air amount of the engine, an engine 63 (corresponding to the engine body 1 or 31) as a combustion engine, and NOx in the engine exhaust. A catalyst 64 that oxidizes and purifies HC and CO, a muffler 65 that silences exhaust noise, an EGR control valve 66 that adjusts the amount of EGR when the exhaust gas is returned to the intake air and recirculated, An air-fuel ratio sensor 67 that measures the air-fuel ratio in the exhaust, an exhaust temperature sensor 68 that measures the temperature of the exhaust, a water temperature sensor 69 that can detect the coolant temperature as voltage or electrical resistance, and an engine speed that detects the engine speed The number sensor 70 and signals from the above sensors are input to control the engine 63, the throttle 62, and the EGR control valve 66. That ECU has a (engine control unit) 71, a.

  FIG. 12 shows the piston motion in the expansion stroke of the expansion exhaust piston (corresponding to the expansion exhaust piston 14 of the first embodiment and the expansion exhaust piston 44 of the second embodiment) according to the present invention at the engine speed (crankshaft speed) N1. A case and an engine speed (crankshaft speed) N2 are shown. Note that N1 <N2.

  Expressing the piston motion of the expansion / exhaust piston in terms of a holding crank angle (details will be described later) and an expansion crank angle (details will be described later), if the rotation speed is low, the expansion crank angle is made smaller and the holding crank angle is made smaller than the expansion crank angle. Make it smaller.

  Here, the holding crank angle is a crankshaft corresponding to a period in which the position of the expansion / exhaust piston is fixed near the top dead center (corresponding to the crankshaft 12 in the first embodiment and the crankshaft 42 in the second embodiment). The expansion crank angle is a rotation angle of the crankshaft corresponding to a period in which the position of the expansion / exhaust piston changes from the top dead center to the bottom dead center.

  In the expansion stroke, when the operation (movement) distance of the expansion exhaust piston from the top dead center with respect to the rotation angle of the crankshaft is changed according to the rotation speed of the crankshaft, and the rotation speed of the crankshaft is low, The operation (movement) distance of the expansion exhaust piston from the top dead center with respect to the rotation angle of the crankshaft is made relatively long. That is, the piston speed when the expansion exhaust piston descends toward the bottom dead center is increased. On the other hand, when the rotation speed of the crankshaft is high, in the expansion stroke, the operation (movement) distance of the expansion exhaust piston from the top dead center with respect to the rotation angle of the crankshaft is relatively shortened. That is, the piston speed when the expansion exhaust piston descends toward the bottom dead center is relatively slow.

  In the engine according to the first embodiment described above, a holding crank angle and an expansion crank angle corresponding to the engine speed are set for the expansion exhaust piston 14 in the expansion stroke. Further, in the engine according to the second embodiment described above, an expansion crank angle corresponding to the engine speed is set for the expansion exhaust piston 44 in the expansion stroke.

  FIG. 13 shows the correlation between the engine efficiency, the expansion crank angle, and the holding crank angle when the engine speed is low. From FIG. 13, it can be seen that the thermal efficiency is improved when the expansion crank angle and the holding crank angle are appropriately set as in the engines of the first and second embodiments described above.

  The maximum efficiency point in FIG. 13 changes according to the engine speed. When the engine speed increases, the direction of the arrow in FIG. 13, that is, both the expansion crank angle and the holding crank angle are relative. It will change in the direction of increasing. Further, the conventional piston motion has a holding crank angle of zero and an expansion crank angle of 180 deg.

  FIG. 14 is a flowchart showing a control flow common to the internal combustion engines of the first and second embodiments described above.

  In step (hereinafter referred to as S) 1, the coolant temperature is detected. In S2, the engine speed is detected. In S3, the piston motion of the expansion exhaust piston is selected from the coolant temperature and the engine speed. The selection of piston motion by this control flow is repeatedly executed.

  FIG. 15 shows a control block corresponding to the piston motion selection calculation of S3 in FIG.

  In a block (hereinafter referred to as “B”) 1, an engine speed correction value is calculated from a coolant temperature detected using a water temperature correction table (described later).

  The corrected engine speed is obtained by adding the engine speed correction value to the detected engine speed.

  And in B2 which is a piston motion selection part, the piston motion of an expansion exhaust piston is selected using the corrected engine speed (corrected engine speed). That is, in this B2, the driving amount of the expansion speed control actuator 18 is determined in the internal combustion engine in the first embodiment, and either the first clutch 50 or the second clutch 51 in the internal combustion engine in the second embodiment. Is selected.

  As shown in FIG. 16, the water temperature correction table is set such that the engine speed correction value is low when the cooling water temperature is low, and the engine speed correction value is high when the cooling water temperature is high. That is, when the coolant temperature is low, the corrected engine speed is lower than the detected engine speed, and when the coolant temperature is high, the corrected engine speed is higher than the detected engine speed. Become.

  If the combustion gas has the same temperature, when the water temperature is low, the wall temperature in the cylinder is low, so the amount of heat received by the cylinder increases. Conversely, when the water temperature is high, the wall temperature in the cylinder is high, so the amount of heat received by the cylinder is low. Therefore, when the water temperature is high, it is equivalent to the water temperature being higher than the engine speed at normal temperature, and when the water temperature is low, it is equivalent to the water temperature being lower than the engine speed at normal temperature.

  FIG. 17 shows a control block corresponding to the piston motion selection unit B2 in FIG.

  In B11, the expansion crank angle is calculated from the corrected engine speed corrected according to the coolant temperature using an expansion crank angle calculation table (described later). In B12, the holding crank angle is calculated from the corrected engine speed corrected according to the coolant temperature, using a holding crank angle calculation table (described later). In B13, the operation (movement) distance of the expansion exhaust piston from the top dead center with respect to the rotation angle of the crankshaft is determined in accordance with the rotation speed of the crankshaft in the expansion stroke using the calculated expansion crank angle and the holding crank angle. To change. That is, in the internal combustion engine in the first embodiment, the drive amount of the expansion speed control actuator 18 is determined from the calculated expansion crank angle and holding crank angle, and in the internal combustion engine in the second embodiment, the calculated expansion is performed. Which of the first clutch 50 and the second clutch 51 is to be engaged is selected from the crank angle and the holding crank angle.

  FIG. 18 shows the above-described expansion crank angle calculation table. As the engine speed increases, the combustion time loss increases more than the cooling loss, so the expansion crank angle is increased. Conversely, when the engine speed is lowered, the cooling loss is increased more than the combustion time loss, so that the expansion crank angle is decreased.

  FIG. 19 shows the holding crank angle calculation table described above. When the engine speed is low, it is difficult to set the in-cylinder pressure and the amount of heat received by the cylinder with the expansion crank angle alone, so the holding crank angle is set to a value smaller than the expansion crank angle. If the rotation speed increases, the in-cylinder pressure and the amount of heat received by the cylinder can be appropriately set by the expansion crank angle, so that the holding crank angle is increased. In addition, it is preferable to optimize the setting of FIG. 18 and FIG. 19 with the ratio of the stroke volume of the engine and the stroke area.

  As described above, in the present invention, when the cam profile of the three-dimensional cam 16 is switched according to the rotation speed of the crankshaft 12 as in the internal combustion engine of the first embodiment, the expansion crank angle and the holding angle are maintained. A cam profile is selected such that the greater the crank angle, the greater the expansion speed of the expansion exhaust piston in the expansion stroke. That is, in the first embodiment, the expansion speed control actuator 18 is controlled so that the low-rotation cam profile is selected. Further, a cam profile is selected in which the expansion speed of the expansion exhaust piston in the expansion stroke becomes relatively smaller as the expansion crank angle and the holding crank angle are smaller. That is, in the first embodiment, the expansion speed control actuator 18 is controlled so that a cam profile for high rotation is selected.

  On the other hand, when separating the intake compression stroke and the expansion / exhaust stroke as in the internal combustion engine of the second embodiment and switching the gear stage according to the rotation speed of the crankshaft, the larger the expansion crank angle and the holding crank angle, A gear with a relatively high rotational speed of the auxiliary crankshaft is selected so that the expansion speed of the expansion exhaust piston in the expansion stroke is relatively large. That is, in the second embodiment, the first clutch 50 is engaged when the expansion crank angle and the holding crank angle are large. In addition, a gear is selected in which the rotation speed of the auxiliary crankshaft is relatively slow so that the expansion crank angle and the holding crank angle are small, so that the expansion speed of the expansion exhaust piston in the expansion stroke is relatively small. That is, in the second embodiment, the second clutch 51 is engaged when the expansion crank angle and the holding crank angle are small.

  The technical idea of the present invention that can be grasped from the above embodiment will be listed together with the effects thereof.

  (1) In the expansion stroke, the piston working distance with respect to the rotation angle of the crankshaft is changed according to the rotation speed of the crankshaft. As a result, the piston working distance with respect to the crankshaft rotation angle in the expansion stroke is changed according to the rotation speed of the crankshaft, thereby reducing the cooling time loss from the low rotation to the high rotation and reducing the combustion time loss. it can.

  (2) In the internal combustion engine described in (1) above, when the rotation speed of the crankshaft is low, the piston operating distance with respect to the rotation angle of the crankshaft is increased in the expansion stroke. As a result, the contact time between the high-temperature combustion gas and the cylinder wall surface at low rotation can be reduced, and cooling loss can be reduced.

  (3) In the internal combustion engine described in the above (1) or (2), when the rotational speed of the crankshaft is high, the piston working distance with respect to the rotational angle of the crankshaft is shortened in the expansion stroke. As a result, the amount by which the piston descends during combustion at high revolutions can be reduced and the in-cylinder pressure can be set appropriately, reducing combustion time loss.

  (4) In the internal combustion engine according to any one of (1) to (3), in the expansion stroke, the piston at the top dead center position is held at a position near the top dead center for a predetermined period according to the rotational speed of the crankshaft. Is done. As a result, the in-cylinder pressure can be set appropriately from low rotation to high rotation, and combustion time loss can be reduced.

  (5) It has a cooling water temperature detecting means for detecting the cooling water temperature of the internal combustion engine, and changes the piston working distance with respect to the crankshaft rotation angle in the expansion stroke according to the cooling water temperature and the rotation speed of the crankshaft. . Thereby, the in-cylinder pressure can be set in consideration of the amount of heat transfer to the cylinder wall surface, and the cooling loss can be reduced while reducing the combustion time loss.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically the structure in 1st Embodiment of the internal combustion engine which concerns on this invention. BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically the structure in 1st Embodiment of the internal combustion engine which concerns on this invention. Explanatory drawing which showed the three-dimensional cam typically. Explanatory drawing which showed typically the correlation with the expansion stroke and exhaust stroke which are performed with an expansion exhaust cylinder, and a three-dimensional cam. The timing chart which shows the operation | movement of the valve | bulb and piston of an internal combustion engine in 1st Embodiment. Explanatory drawing which showed typically the structure in 2nd Embodiment of the internal combustion engine which concerns on this invention. Explanatory drawing which showed typically the structure in 2nd Embodiment of the internal combustion engine which concerns on this invention. Explanatory drawing which showed typically the structure in 2nd Embodiment of the internal combustion engine which concerns on this invention. The internal combustion engine in 2nd Embodiment WHEREIN: The timing chart which shows the operation | movement of a valve | bulb and piston when an engine speed is low. The internal combustion engine in 2nd Embodiment WHEREIN: The timing chart which shows the operation | movement of a valve | bulb and piston when an engine speed is high. BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which showed typically the engine system structure of the internal combustion engine which concerns on this invention. The internal combustion engine which concerns on this invention WHEREIN: Explanatory drawing which shows the piston motion in the expansion stroke of an expansion exhaust piston. Explanatory drawing which showed the correlation with the engine efficiency, an expansion crank angle, and a holding | maintenance crank angle at the time of engine speed low. The flowchart which shows the flow of control of the internal combustion engine which concerns on this invention. The control block which corresponds to the piston motion selection calculation of S3 in FIG. The water temperature correction table used by B1 of FIG. FIG. 16 is a control block corresponding to a piston motion selection unit of B2 in FIG. FIG. 18 is an expansion crank angle calculation table used in B11 of FIG. FIG. 18 is a holding crank angle calculation table used in B12 of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 ... Intake compression cylinder 3 ... Expansion exhaust cylinder 5 ... Intake valve 7 ... Compression valve 9 ... Exhaust valve 10 ... Intake compression piston 12 ... Crankshaft 14 ... Expansion exhaust piston 16 ... Three-dimensional cam 18 ... Expansion speed control actuator 32 ... Intake compression cylinder 33 ... Expansion exhaust cylinder 35 ... Intake valve 37 ... Compression valve 39 ... Exhaust valve 40 ... Intake compression piston 42 ... Crankshaft 44 ... Expansion exhaust piston 45 ... Intake compression first speed gear 46 ... Intake compression second speed gear 48 ... Expansion exhaust 1st gear 49 ... Expansion exhaust 2nd gear 50 ... 1st clutch 51 ... 2nd clutch 52 ... Auxiliary crankshaft

Claims (5)

  An internal combustion engine characterized in that, in an expansion stroke, a piston working distance with respect to a rotation angle of the crankshaft is changed according to a rotation speed of the crankshaft.   2. The internal combustion engine according to claim 1, wherein when the rotation speed of the crankshaft is low, the piston operating distance with respect to the rotation angle of the crankshaft is increased in the expansion stroke.   3. The internal combustion engine according to claim 1, wherein when the rotation speed of the crankshaft is high, the piston operating distance with respect to the rotation angle of the crankshaft is shortened in the expansion stroke.   The internal combustion engine according to any one of claims 1 to 3, wherein the piston at the top dead center position is held at a position near the top dead center for a predetermined period according to the rotational speed of the crankshaft in the expansion stroke.   A cooling water temperature detecting means for detecting a cooling water temperature of the internal combustion engine is provided, and the piston working distance with respect to the rotation angle of the crankshaft is changed in the expansion stroke in accordance with the cooling water temperature and the rotation speed of the crankshaft. An internal combustion engine.