JP2008111397A - Cycle variable stroke engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cycle variable stroke engine suitable for reducing cylinder residual gas. <P>SOLUTION: The cycle variable stroke engine is equipped with a cycle variable stroke mechanism that rotates a crankshaft 9 by a reciprocating piston 22 and causes the piston stroke characteristic to be different between an exhaust top dead center position (TDC) and a compression top dead center position (TDC) of the piston 22 in one cycle, and with a variable valve mechanism capable of control for simultaneously and continuously varying the lift and operation angle of an intake valve 61, and is adapted to retard the closing timing of the intake valve 61 to the proximity of the intake bottom dead center by the variable valve mechanism when the height of the exhaust top dead center (exhaust TDC) is set to be higher than the height of the compression top dead center (compression TDC) by the cycle variable stroke mechanism. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cycle variable stroke engine having piston stroke characteristics in which an exhaust top dead center position (TDC) and a compression top dead center position (TDC) of a piston in one cycle are different, and in particular, to reduce in-cylinder residual gas. It relates to a suitable cycle variable stroke engine.

  In order to make it possible to change the engine compression ratio, a cycle variable stroke engine has been proposed in which the piston position at the exhaust top dead center is different from the piston position at the compression top dead center (see Patent Document 1).

This is because the upper link connected to the piston pin of the piston and the lower link connected to the crank pin of the crankshaft are connected to each other, and one end of a control link that restricts the freedom of the upper link and the lower link to the lower link. And the other end of this control link is fitted to the eccentric shaft portion of the rotary shaft so as to be rotatable around the center of oscillation, and the rotational angular speed of this rotary shaft is set to 1/2 of the rotational angular speed of the crankshaft. Configured. As a result, the piston position at the exhaust top dead center is set lower than the piston position at the compression top dead center, avoiding interference between the piston and the intake and exhaust valves near the exhaust top dead center, and increasing the compression ratio. I try to figure it out.
Japanese Patent Laid-Open No. 2003-13764

  However, in the above-described conventional example, the piston position at the exhaust top dead center is set lower than the piston position at the compression top dead center, thereby reducing the fuel loss by reducing the pump loss due to the increase in cylinder residual gas and the high expansion ratio. Although it can be improved, the amount of residual gas in the cylinder is large, so that the combustion tends to become unstable during idling / low load, especially during cold operation.

  The present invention has been made in view of the above problems, and an object thereof is to provide a cycle variable stroke engine suitable for reducing in-cylinder residual gas.

  The present invention relates to a cycle variable stroke mechanism in which a crankshaft is rotated by a reciprocating piston and piston stroke characteristics differ between an exhaust top dead center position (TDC) and a compression top dead center position (TDC) of the piston in one cycle. And a variable valve mechanism that can simultaneously and continuously expand and reduce the lift and operating angle of the intake valve, and the cycle top stroke (exhaust TDC) height is compressed top dead by the cycle variable stroke mechanism. When set higher than the point (compression TDC) height, the variable valve mechanism retards the closing timing of the intake valve to the vicinity of the intake bottom dead center.

  Therefore, according to the present invention, when the exhaust top dead center (exhaust TDC) height is set higher than the compression top dead center (compression TDC) height by the cycle variable stroke mechanism, the intake valve closing timing is determined by the variable valve mechanism. By retarding in the vicinity of the bottom dead center, the in-cylinder residual gas can be reduced, and combustion is performed even under conditions where the effective compression ratio is low such that the closing timing of the intake valve is close to or after the bottom dead center. Can be stabilized, and the exhaust temperature when cold can be raised.

  Hereinafter, a cycle variable stroke engine of the present invention will be described based on an embodiment. 1 and 2 show a cycle variable stroke mechanism constituting a cycle variable stroke engine according to the present invention.

  1 and 2, a plurality of cylinders 21 are formed along a cylinder row in a cylinder block 20 constituting a part of the engine body, and pistons 22 are disposed in the respective cylinders 21 so as to be moved up and down. The piston pin 1 of each piston 22 is mechanically linked to the crankpin 2 of the crankshaft 9 by a plurality of links, specifically, the upper link 3 and the lower link 4. One end of the upper link 3 is rotatably connected to the piston pin 1, the lower link 4 is rotatably connected to the crank pin 2, and the other end of the upper link 3 and the lower link 4 are connected via a first connecting pin 24. They are connected to each other in a rotatable manner. The crankshaft 9 is provided with a counterweight 9a.

  One end 5 a of a control link 5 is rotatably connected to the lower link 4 via a second connecting pin 25, and the other end 5 b of the control link 5 is around a swing center 5 c provided in the cylinder block 20. It is supported so that it can swing. The connecting positions of the crank pin 2, the first connecting pin 24, and the second connecting pin 25 that are connected to the lower link 4 are not arranged on the same straight line but are arranged in a substantially triangular shape.

  The support center of the swing center 5c of the control link 5 with respect to the cylinder block 20 is configured to be changed by the rotating shaft 6 that rotates in conjunction with the rotation of the crankshaft 9. That is, the rotating shaft 6 extends in the cylinder row direction, and is rotatably supported by the plurality of journal portions 8 on the cylinder block 20 side via the bearing bracket 26. The rotating shaft 6 has a cylindrical or columnar eccentric shaft portion (eccentric portion) 7 which is eccentric with respect to the axial center of the journal portion 8 which is the rotation center 6a of the rotating shaft 6 itself. The other end 5 b of the control link 5 is rotatably fitted on the outer peripheral surface of each eccentric shaft portion 7. That is, the other end 5b of the control link 5 is rotatably supported by the eccentric shaft portion 7, and the shaft center of the eccentric shaft portion 7 becomes the swing center 5c of the control link 5 with respect to the engine body.

  Further, the drive shaft 12A fixed to one end of the crankshaft 9, the driven pulley 12B fixed to one end of the rotary shaft 6, and the pulley belt 13 spanned between the pulleys 12A and 12B, are separated from the crankshaft 9. A rotational power transmission mechanism that transmits rotational power to the rotary shaft 6 is configured. The radius of the driven pulley 12B is set to be twice the radius of the drive pulley 12A so that the rotational speed of the rotary shaft 6 with respect to the crankshaft 9 is halved. Since the reduction ratio of the rotational motion transmitted from the crankshaft 9 to the rotary shaft 6 is set to 1/2, the rotary shaft 6 makes one rotation during one cycle of the engine.

  Therefore, when the rotary shaft 6 rotates in conjunction with the crankshaft 9, the support position of the swing center 5c of the control link 5 moves via the eccentric shaft portion 7 for each cycle, so that it is twice in one cycle. The piston stroke characteristics of the piston reciprocating motion can be different from each other. That is, the piston stroke characteristics can be different between the exhaust-intake stroke and the compression-expansion stroke.

  FIG. 3 shows that the crankshaft 9 is rotated away from the top dead center from the rotary shaft 6 and the support position of the swing center 5c of the control link 5 via the eccentric shaft portion 7 The rotary shaft 6 is rotated so that the position is lowered from the rotation center 6a of the rotary shaft 6 during the intake stroke, and the position is raised from the rotation center 6a of the rotary shaft 6 during the compression-expansion stroke including the compression top dead center. The piston stroke characteristic in the case of being made is shown. A characteristic indicated by a thin broken line is a piston stroke characteristic in a conventional engine in which the heights of the exhaust top dead center and the compression top dead center are set to be the same.

  The swing center 5c of the control link 5 is the lowest position at the exhaust top dead center during the exhaust-intake stroke, i.e., raises the piston position via the lower link 4, and the compression-expansion stroke. The position at which the compression top dead center rises most, that is, the piston position is lowered with the lower link 4 interposed therebetween, and the piston height position at the exhaust top dead center becomes higher than the piston height position at the compression top dead center. I am doing so.

  Further, accompanying the increase in the vertical position of the piston 22 at the exhaust top dead center, the piston speed from the bottom dead center position to the top dead center in the exhaust stroke is relatively increased by the stroke increase, Also, in the intake stroke starting from the exhaust top dead center, the piston speed to the intake bottom dead center is relatively increased. On the contrary, the piston speed from the bottom dead center position to the top dead center in the compression stroke is relatively decreased by the stroke reduction accompanying the downward movement of the piston 22 at the compression top dead center. Also, in the expansion stroke starting from the compression top dead center, the piston speed to the expansion bottom dead center is relatively reduced.

  FIG. 4 shows the piston stroke characteristic exaggerated so that the characteristic of the piston stroke characteristic in FIG. 3 becomes clear. This piston stroke characteristic is that when the crankshaft 9 is rotated away from the piston top dead center in the direction away from the rotary shaft 6, the intake bottom dead center ( BDC) is slightly advanced, and the intake top dead center (BDC) to compression top dead center (TDC) position is determined from the crank angle from the exhaust top dead center (TDC) to the intake bottom dead center (BDC) piston position. The crank angle up to can be increased.

  By setting the exhaust top dead center (exhaust TDC) height higher than the compression top dead center (compression TDC) height, the in-cylinder residual gas is reduced, and the compression stroke after the intake bottom dead center is started. Combustion can be stabilized even under such a low effective compression ratio that the intake valve closes at the time.

  Further, the crank angle from the exhaust top dead center (exhaust TDC) to the intake bottom dead center (intake BDC) is smaller than the crank angle from the intake bottom dead center (intake BDC) to the compression top dead center (compression TDC). Combustion can be improved by enhancing the in-cylinder gas flow by increasing the piston speed in the intake stroke.

  Moreover, since the exhaust top dead center (exhaust TDC) height is set higher than the compression top dead center (compression TDC) height, the piston speed in the vicinity of the compression top dead center can be increased by a general single link piston crank. Since it becomes moderate around 20% compared with the mechanism, it is possible to stabilize the combustion by assisting the generation and growth of the initial flame kernel even in the cold machine where the combustion speed is slow.

  Returning to FIGS. 1 and 2, a rotational power transmission path from the driven gear 10 </ b> B to the rotational shaft 6 is provided with a rotational phase changing mechanism 11 that changes the rotational phase of the rotational shaft 6 relative to the rotational phase of the crankshaft 9. The rotation phase change mechanism 11 can be applied with a known valve timing adjustment mechanism (VTC) structure using a helical gear or vane that changes the phase of the camshaft with respect to the rotation phase of the crankshaft 9, for example, It is driven by an electromagnetic solenoid or the like. The rotation phase change mechanism 11 is operated based on a control signal from an engine control unit (not shown), and the phase of the rotation shaft 6 with respect to the crankshaft 9 is variably controlled according to the operating state of the engine.

  The rotation phase change mechanism 11 supports the swing center 5c of the control link 5 via the eccentric shaft portion 7 by changing the rotation phase of the rotation shaft 6 with respect to the rotation phase of the crankshaft 9 according to the engine operating state. The engine compression ratio can be changed by changing the position and changing the posture of the links 3 and 4.

  Next, a variable valve mechanism that makes the intake valve closing timing variable, which is applied to the cycle variable stroke engine of the present embodiment, will be described with reference to FIG. The intake valve side variable valve mechanism of the internal combustion engine includes a lift / operation angle variable mechanism 51 that changes the lift / operation angle of the intake valve, and a phase (phase with respect to a crankshaft (not shown)) of the lift is advanced or The phase variable mechanism 71 for retarding the angle is combined.

  The lift / operating angle variable mechanism 51 will be described first. The lift / operating angle variable mechanism 51 has been previously proposed by the applicant of the present application. However, since it has been publicly known, for example, in Japanese Patent Application Laid-Open No. 11-107725, only the outline thereof will be described. The lift / operating angle variable mechanism 51 includes a drive shaft 52 rotatably supported by a cam bracket (not shown) above the cylinder head, an eccentric cam 53 fixed to the drive shaft 52 by press-fitting, and the like. A control shaft 62 that is rotatably supported by the same cam bracket at a position above the drive shaft 52 and arranged in parallel to the drive shaft 52, and a rocker arm that is swingably supported by an eccentric cam portion 68 of the control shaft 62. 56 and a swing cam 59 that abuts against the tappet 60 disposed at the upper end of each intake valve 61.

  The eccentric cam 53 and the rocker arm 56 are linked by a link arm 54, and the rocker arm 56 and the swing cam 59 are linked by a link member 58. The drive shaft 52 is driven by the crankshaft of the engine via a timing chain or a timing belt. The eccentric cam 53 has a circular outer peripheral surface centered at a point offset from the shaft center of the drive shaft 52 by a predetermined amount, and an annular portion of the link arm 54 is rotatably fitted to the outer peripheral surface. Yes.

  The rocker arm 56 has a substantially central portion supported by the eccentric cam portion 68 so as to be swingable. The one end portion of the rocker arm 56 is linked to the arm portion of the link arm 54 via a connecting pin 55 and the other end portion. Further, the upper end portion of the link member 58 is linked via the connecting pin 57. The eccentric cam portion 68 is eccentric from the axis of the control shaft 62, and the rocking center of the rocker arm 56 changes according to the angular position of the control shaft 62.

  The swing cam 59 is fitted to the outer periphery of the drive shaft 52 and is rotatably supported, and a lower end portion of the link member 58 is linked to an end portion extending sideways through a connecting pin 67. . On the lower surface of the swing cam 59, a base circle surface concentric with the drive shaft 52 and a cam surface extending in a predetermined curve from the base circle surface are continuously formed. The base circle surface and the cam surface come into contact with the upper surface of the tappet 60 according to the swing position of the swing cam 59. In other words, the base circle surface is a section where the lift amount becomes 0 as a base circle section, and when the swing cam 59 swings and the cam surface contacts the tappet 60, the base circle section lifts gradually. A slight lap section is provided between the base circle section and the lift section.

  The control shaft 62 is configured to rotate within a predetermined angle range by a lift / operating angle control actuator 63 provided at one end. The lift / operating angle control actuator 63 includes, for example, a servo motor that drives the control shaft 62 via the worm gear 65, and is controlled by a control signal from the engine control unit 69. The rotation angle of the control shaft 62 is detected by the control shaft sensor 64.

  When the drive shaft 52 rotates, the lift / operating angle variable mechanism 51 configured as described above moves the link arm 4 up and down by the cam action of the eccentric cam 53, and the rocker arm 56 swings accordingly. The swing of the rocker arm 56 is transmitted to the swing cam 59 via the link member 58 to swing the swing cam 59. By the cam action of the swing cam 59, the tappet 60 is pressed and acts to lift the intake valve 61.

  When the angle of the control shaft 62 is changed via the lift / operation angle control actuator 63, the initial position of the rocker arm 56 changes and the initial swing position of the swing cam 59 changes. For example, if the eccentric cam portion 68 is positioned upward in the figure, the rocker arm 56 is positioned upward as a whole, and the end of the swing cam 59 on the side of the connecting pin 67 is relatively lifted upward. Become. That is, the initial position of the swing cam 59 is inclined in a direction in which the cam surface is separated from the tappet 60. Therefore, when the swing cam 59 swings with the rotation of the drive shaft 52, the base circle surface is kept in contact with the tappet 60 for a long time, and the period during which the cam surface is in contact with the tappet 60 is short. Therefore, the lift amount is reduced as a whole, and the angle range from the opening timing to the closing timing, that is, the operating angle is also reduced.

  On the contrary, if the eccentric cam portion 68 is positioned downward in the figure, the rocker arm 56 is positioned downward as a whole, and the end portion on the connecting pin 67 side of the swing cam 59 is pushed downward relatively. It becomes a state. That is, the initial position of the swing cam 59 is inclined in a direction in which the cam surface approaches the tappet 60. Therefore, when the swing cam 59 swings with the rotation of the drive shaft 52, the portion that contacts the tappet 60 immediately shifts from the base circle surface to the cam surface. Therefore, the lift amount is increased as a whole, and the operating angle is increased.

  Since the initial position of the eccentric cam portion 68 can be continuously changed, the valve lift characteristic is continuously changed accordingly. That is, the lift and the operating angle can be continuously expanded and reduced simultaneously. Depending on the layout of each part, for example, the opening timing and closing timing of the intake valve 61 change substantially symmetrically with the change in the lift and operating angle.

  The phase variable mechanism 71 includes a sprocket 72 provided at a front end portion of the drive shaft 52, and a phase control actuator 73 that relatively rotates the sprocket 72 and the drive shaft 52 within a predetermined angle range. , Is composed of. The sprocket 72 is linked to the crankshaft via a timing chain or timing belt (not shown). The phase control actuator 73 is composed of, for example, a hydraulic or electromagnetic rotary actuator, and is controlled by a control signal from the engine control unit 69. Due to the action of the phase control actuator 73, the sprocket 72 and the drive shaft 52 rotate relatively, and the lift center angle in the valve lift is retarded.

  That is, the lift characteristic curve itself does not change, and the whole advances or retards. This change can also be obtained continuously. The control state of the phase variable mechanism 71 is detected by a drive shaft sensor 66 that responds to the rotational position of the drive shaft 52. The lift / operating angle variable mechanism 51 and the phase variable mechanism 71 are optimally controlled by the ECU in accordance with the engine operating conditions. The cycle variable stroke engine of this embodiment provided with the variable valve mechanism described above on the intake valve side can also control the intake air amount by variable control of the intake valve 61 without depending on the throttle valve.

  Next, control of the valve lift characteristics of the intake valve under typical operating conditions will be described based on FIG. FIG. 6 shows a valve lift control region in which the intake air amount is controlled mainly focusing on the lift amount in the operation region, and a valve timing control region in which the intake air amount control is mainly focused on the valve timing. And. The valve lift control region corresponds to an extremely low load region including idle.

  In the cycle variable stroke engine of the present embodiment, the exhaust top dead center (exhaust TDC) height is set higher than the compression top dead center (compression TDC) height, so that the in-cylinder residual gas can be reduced, resulting in a knock limit. Can be expanded. In addition, the intake stroke amount can be increased and the piston speed in the intake stroke can be increased, so that the gas flow in the cylinder can be strengthened, combustion can be stabilized, and the output can be improved. Can do.

  When the load is low, including idling at the time of cooling such as immediately after starting, the lift amount of the intake valve 61 is set to a minimum lift, and the phase of the lift center angle by the phase variable mechanism 71 is further delayed by a broken line in the figure. As shown, the closing timing is delayed so that the intake valve 61 is closed when the compression stroke after the intake bottom dead center is started. By further delaying the phase of the lift center angle, the opening timing of the intake valve 61 is similarly delayed.

  However, as described above, since the exhaust top dead center (exhaust TDC) height is set higher than the compression top dead center (compression TDC) height, the residual gas is reduced. Combustion can be stabilized even under a condition where the effective compression ratio is low such that the intake valve 61 closes when the compression stroke starts.

  Moreover, the crank angle from the exhaust top dead center (exhaust TDC) to the intake bottom dead center (intake BDC) is smaller than the crank angle from the intake bottom dead center (intake BDC) to the compression top dead center (compression TDC). Combustion can be improved by enhancing the in-cylinder gas flow by increasing the piston speed in the intake stroke.

  Therefore, the pumping loss is increased by delaying the closing timing of the intake valve 61 after the intake bottom dead center (BDC), and the exhaust gas temperature can be raised by the working gas UP. Further, the ignition timing can be delayed (retarded), and the exhaust temperature can be further increased. Therefore, the catalyst during cold operation can be activated early.

  Moreover, since the exhaust top dead center (exhaust TDC) height is set higher than the compression top dead center (compression TDC) height, the piston speed in the vicinity of the compression top dead center can be increased by a general single link piston crank. Since it becomes moderate around 20% compared with the mechanism, it is possible to stabilize the combustion by assisting the generation and growth of the initial flame kernel even in the cold machine where the combustion speed is slow.

  In an extremely low load range such as idle after warm-up, the lift amount of the intake valve 61 is set to a minimum lift. In particular, the lift amount is so small that the phase of the lift center angle does not affect the intake air amount. Then, the phase of the lift center angle by the phase variable mechanism 71 is set to the most retarded position, so that the closing timing is set to the position immediately before the bottom dead center.

  By setting the minimum lift in this way, the intake flow becomes choked in the gap between the intake valves 61, and a minute flow rate required in an extremely low load region can be stably obtained. And since the closing time is near bottom dead center, even in an operating state where the effective compression ratio is not sufficiently high, relatively good combustion can be ensured in combination with the improvement of gas flow by the minimal lift. . Moreover, the exhaust top dead center (exhaust TDC) height is set to be higher than the compression top dead center (compression TDC) height, and the piston speed in the intake stroke is increased, thereby further promoting the gas flow. To do.

  In addition, since the exhaust top dead center (exhaust TDC) height is set higher than the compression top dead center (compression TDC) height, the residual gas is reduced, so the compression stroke after the intake bottom dead center starts. Combustion can be stabilized even under a condition where the effective compression ratio is low such that the intake valve 61 is closed at the time when the intake valve 61 is closed. Moreover, the crank angle from the exhaust top dead center (exhaust TDC) to the intake bottom dead center (intake BDC) is smaller than the crank angle from the intake bottom dead center (intake BDC) to the compression top dead center (compression TDC). Combustion can be improved by enhancing the in-cylinder gas flow by increasing the piston speed in the intake stroke.

  In a low load region (including idle states where auxiliary load is applied) that is greater than the extremely low load region such as idle, the lift / operating angle is increased and the lift center angle is set to the advanced position. . At this time, as described above, the intake air amount control is performed in consideration of the valve timing, and the intake air amount is controlled to a relatively small amount by advancing the intake valve closing timing. As a result, the lift / operating angle becomes somewhat large, and the pumping loss due to the intake valve 61 is reduced.

  In addition, since the exhaust top dead center (exhaust TDC) height is set higher than the compression top dead center (compression TDC) height, the residual gas is reduced, so the compression stroke after the intake bottom dead center starts. Combustion can be stabilized even under a condition where the effective compression ratio is low such that the intake valve closes at the time when the intake valve is closed. Moreover, the crank angle from the exhaust top dead center (exhaust TDC) to the intake bottom dead center (intake BDC) is smaller than the crank angle from the intake bottom dead center (intake BDC) to the compression top dead center (compression TDC). Combustion can be improved by enhancing the in-cylinder gas flow by increasing the piston speed in the intake stroke.

  Note that in the case of a minimal lift in an extremely low load range such as idle, the intake air amount hardly changes even if the phase is changed, as described above, so when shifting from the very low load range to the low load range, Prior to the change, it is necessary to enlarge the lift and operating angle. The same applies when a load of auxiliary equipment such as an air conditioning compressor is applied.

  In the middle load range where the load further increases and the combustion becomes stable, the lift / operating angle of the intake valve 61 is further expanded while the phase of the lift center angle is advanced. The phase of the lift center angle is the most advanced state at a certain point in the middle load region. Thereby, internal EGR is utilized and the pumping loss can be further reduced.

  In addition, at the maximum load, the phase variable mechanism 71 is controlled so that the lift / operation angle is further expanded and the optimum valve timing is obtained. As shown in the figure, the optimum valve lift characteristic varies depending on the engine speed. Since the combustion state is greatly affected by the fuel atomization and compression stroke temperature, it is easy to detect the engine temperature.

  In the above embodiment, as the variable valve mechanism that makes the intake valve closing timing variable, the lift / operation angle variable mechanism 51 that changes the lift / operation angle of the intake valve and the phase of the center angle of the lift (not shown) The phase variable mechanism 71 for advancing or retarding the phase with respect to the crankshaft has been described. However, as shown in FIG. 7, the electromagnetic valve that opens and closes the intake valve and the exhaust valve by an electrical signal is used. It may be configured.

  Note that this variable valve mechanism has been previously proposed by the applicant of the present invention. However, since this variable valve mechanism is publicly known, for example, in Japanese Patent Application Laid-Open No. 2001-173470, only the outline thereof will be described. In this electromagnetic drive device (variable valve operating device) for the intake valve 61 and the exhaust valve, a plate-like movable element 82 is attached to a valve shaft 81 of a valve body 80, and this movable element 82 is attached to a neutral position by springs 83 and 84. It is fast. A valve opening electromagnetic coil 85 is disposed below the movable element 82, and a valve closing electromagnetic coil 86 is disposed above the movable element 82.

  When opening the valve, after energizing the upper valve closing electromagnetic coil 86, the lower valve opening electromagnetic coil 85 is energized to attract the mover 82 downward, The valve body 80 is lifted and opened. Conversely, when closing the valve, by energizing the lower valve opening electromagnetic coil 85 and then energizing the upper valve closing electromagnetic coil 86 to attract the mover 82 upward, The valve body 80 is seated on the seat portion and closed. With the variable valve mechanism having such a configuration, the intake air amount can be controlled according to the load by the variable control of the intake valve closing timing or the lift amount in the low and medium load region.

  Moreover, in the said embodiment, what transmits to the rotating shaft 6 via the rotational power transmission mechanism which makes the rotational power from the crankshaft 9 1/2 rotation as a drive mechanism of the rotating shaft 6 of a cycle variable stroke engine is demonstrated. However, although not shown in the figure, it is very good that the rotary shaft 6 is rotated at 1/2 the number of revolutions of the crankshaft by a driving actuator independent of the crankshaft 9. In this case, the top dead center position and the bottom dead center position and the crank angle position thereof can be adjusted in a free mode within the cycle, instead of being uniquely linked with the rotation of the crankshaft 9. .

  In the present embodiment, the following effects can be achieved.

  (A) Rotation of the crankshaft 9 by the reciprocating piston 22 makes the cycle variable so that the piston stroke characteristics differ between the exhaust top dead center position (TDC) and the compression top dead center position (TDC) of the piston 22 in one cycle. In addition to a stroke mechanism, it also has a variable valve mechanism that can simultaneously and continuously change the lift and operating angle of the intake valve 61. The cycle variable stroke mechanism compresses the exhaust top dead center (exhaust TDC) height. When the height is set higher than the dead point (compression TDC) height, the closing timing of the intake valve 61 is retarded to the vicinity of the intake bottom dead center by a variable valve mechanism. For this reason, in-cylinder residual gas can be reduced, combustion can be stabilized even under conditions where the effective compression ratio is low such that the closing timing of the intake valve 61 is in the vicinity of the intake bottom dead center or after the bottom dead center, By setting the intake valve closing timing (IVC) after the intake bottom dead center (BDC), the pump loss increases, the exhaust gas temperature is increased by the working gas UP, and the catalyst during cold operation can be activated early.

  (A) The crank angle from the exhaust top dead center to the intake bottom dead center of the cycle in which the exhaust top dead center (exhaust TDC) height is set higher than the compression top dead center (compression TDC) height by the cycle variable stroke mechanism is By making it smaller than the crank angle from the intake bottom dead center to the compression top dead center, the cylinder gas flow can be strengthened by increasing the piston speed in the intake stroke, combustion can be improved, and the ignition timing can be retarded. This makes it possible to raise the exhaust temperature.

  (C) The cycle variable stroke mechanism includes a multi-link type piston-crank device in which the piston pin 1 of the piston 22 and the crank pin 2 of the crankshaft 9 are linked by a plurality of links 3, 4. The control link 5 that regulates the degree of freedom of 4 is rotatably connected at one end to one of the plurality of links 3 and 4 and the other end of the control link 5 is rotatable around the swing center 5C. The piston position at the exhaust top dead center is set higher than the piston position at the compression top dead center by being rotated synchronously at a rotational speed of 1/2 with respect to the rotation of the crankshaft 9. Piston stroke characteristics close to vibration are obtained, and the piston speed around the compression top dead center (TDC) is 20% compared to a general single link piston crank mechanism. Becomes the rear gentle, even when slow burning rate cold, generation of the initial flame kernel, the help growth combustion can be stabilized.

1 is a cross-sectional view of a cycle variable stroke engine showing an embodiment of the present invention. The schematic block diagram of a cycle variable stroke mechanism similarly. The characteristic view which shows the piston stroke characteristic of the cycle variable stroke engine of this embodiment. Explanatory drawing of the piston stroke characteristic of the cycle variable stroke engine of this embodiment. The perspective view which shows a variable valve mechanism. The characteristic view which shows a valve lift control area and a valve timing control area. Schematic which shows another Example of a variable valve mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piston pin 2 Crank pin 3 Upper link 4 Lower link 5 Control link 5C Oscillation center 6 Rotating shaft 7 Eccentric shaft part 9 Crank shaft 11 Rotation phase change mechanism 51 Lift / operation angle variable mechanism 52 ... Drive shaft 53 ... Eccentric cam 56 ... Rocker arm 58 ... Link member 59 ... Swing cam 61 ... Intake valve 62 ... Control shaft 69 ... Engine control unit 71 ... Phase variable mechanism

Claims (3)

A crankshaft is rotated by a reciprocating piston, and a cycle variable stroke mechanism having different piston stroke characteristics at an exhaust top dead center position (TDC) and a compression top dead center position (TDC) of the piston in one cycle is provided. Equipped with a variable valve mechanism that can simultaneously and continuously expand and reduce the lift and operating angle of the intake valve,
When the exhaust top dead center (exhaust TDC) height is set higher than the compression top dead center (compression TDC) height by the cycle variable stroke mechanism, the closing timing of the intake valve is made close to the intake bottom dead center by the variable valve mechanism. A cycle variable stroke engine characterized by retarding.   The crank angle from the exhaust top dead center to the intake bottom dead center of the cycle in which the exhaust top dead center (exhaust TDC) height is set higher than the compression top dead center (compression TDC) height by the cycle variable stroke mechanism is The cycle variable stroke engine according to claim 1, wherein the engine is smaller than a crank angle from a dead center to a compression top dead center. The cycle variable stroke mechanism includes a multi-link type piston-crank device in which a piston pin of a piston and a crank pin of a crankshaft are linked by a plurality of links,
The control link that regulates the degree of freedom of the plurality of links, one end of which is rotatably connected to one of the plurality of links, and the other end of the control link is rotatably supported around the swing center, The piston position at the exhaust top dead center is made higher than the piston position at the compression top dead center by being rotated synchronously at a rotational speed of 1/2 with respect to the rotation of the crankshaft. The cycle variable stroke engine according to claim 2.