JP2007107407A - Engine system and vehicle equipped therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine system for performing stable self-igniting combustion even in high speed revolution, and to provide a vehicle equipped therewith. <P>SOLUTION: The engine system 200 comprises an ECU 50 and an engine 100. When the engine 100 performs HCCI combustion, the ECU 50 controls each part of the engine system 200 to perform self-igniting combustion at a target combustion timing. The target combustion timing is set to be longer as the revolution speed of the engine 100 is higher while keeping a time from a compression top dead center to the target combustion timing always constant. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an engine system and a vehicle including the same.

  A method to reduce engine heat loss and pump loss by reducing the fuel concentration in the air-fuel mixture (lean air-fuel ratio) or reintroducing exhaust gas into the cylinder to improve engine thermal efficiency It has been known.

  However, in a spark ignition engine that uses a spark plug to ignite an air-fuel mixture, when the air-fuel ratio is made lean or a large amount of exhaust gas is reintroduced, the combustion speed of the air-fuel mixture decreases and the combustion state becomes unstable. become. For this reason, the thermal efficiency of the engine cannot be significantly improved.

  As a technique for preventing instability of the combustion state as described above, an HCCI (Homogeneous-Charge Compression-Ignition Combustion) system is known. The HCCI method increases the in-cylinder temperature by compressing the air-fuel mixture, and self-ignites the air-fuel mixture without spark ignition. According to the HCCI method, a combustion reaction occurs from a plurality of locations of the air-fuel mixture, so that the combustion speed does not decrease and stable combustion is possible.

By the way, in the combustion reaction of the air-fuel mixture, it is known that the combustion becomes unstable when the combustion period is excessively prolonged, and the hitting sound and knocking vibration increase when the combustion period is excessively short. Therefore, for example, in the compression self-ignition internal combustion engine of Patent Document 1, the main combustion time and the main combustion period are defined, and the combustion time is set so that the main combustion period falls between the first limit period and the second limit period. And controlling the combustion period.
JP 2001-355484 A

  Here, in Patent Document 1, the main combustion period is a long-term first limit period determined by combustion stability with respect to the main combustion time, and a short-term second limit period determined by sounding or knocking. Must be set between. Further, the retard limit of the main combustion timing is set so as to change to the advance side as the engine speed increases. In this case, as the engine speed increases, the establishment range of the main combustion period and the main combustion time decreases. That is, in the compression self-ignition internal combustion engine of Patent Document 1, the region where self-ignition combustion is possible becomes narrower as the engine speed increases.

  An object of the present invention is to provide an engine system capable of performing stable self-ignition combustion even at high revolutions, and a vehicle including the same.

  (1) An engine system according to a first aspect of the present invention is an engine system that drives a mechanical device, includes an engine that has a cylinder, and an air-fuel mixture in the cylinder performs self-ignition combustion, and detects an engine speed. And a control means for controlling the timing of the self-ignition of the air-fuel mixture when the engine is performing self-ignition combustion. The control means determines the engine speed detected by the speed detection means. The self-ignition timing of the air-fuel mixture is controlled so that the self-ignition timing of the air-fuel mixture is retarded with the increase.

  In the engine system according to the present invention, the engine speed is detected by the engine speed detecting means. The control means retards the timing of the self-ignition of the air-fuel mixture as the engine speed increases.

  In this case, since the combustion timing is retarded as the engine speed increases, the combustion period of the air-fuel mixture is prevented from being shortened even when the engine operates at a high speed. As a result, even when the engine is operating at a high speed, stable self-ignition combustion in which hitting sound and knocking are prevented can be achieved, and damage to the engine can be prevented.

  (2) The control means may control the self-ignition timing of the air-fuel mixture so that the time from compression top dead center to self-ignition is always equal.

  In this case, the temperature and pressure in the cylinder and their holding time are also maintained substantially constant. Combustion stability in self-ignited combustion is greatly affected by the temperature and pressure in the cylinder and their retention time. Therefore, it is possible to always obtain good combustion stability by controlling the timing of the self-ignition of the air-fuel mixture so that the time from compression top dead center to self ignition is always equal.

  (3) The engine system further includes combustion timing measuring means for measuring the combustion timing of the air-fuel mixture, and storage means for storing the optimal combustion timing of the air-fuel mixture according to the engine speed, and the control means includes combustion The self-ignition timing of the air-fuel mixture may be controlled so that the error between the combustion timing measured by the timing measuring means and the optimum combustion timing stored in the storage means becomes small.

  In this case, the self-ignition timing of the air-fuel mixture is controlled so as to approach the optimum combustion timing stored in the storage means. Thereby, more stable self-ignition combustion becomes possible, and damage to the engine can be surely prevented.

  (4) The engine system may further include ignition means for spark-igniting the air-fuel mixture, and the control means may cause the air-fuel mixture to undergo spark ignition combustion by the ignition means when the absolute value of the error is larger than a predetermined value.

  In this case, when the combustion timing actually measured by the combustion timing measuring means is greatly different from the optimum combustion timing stored in the storage means, spark ignition combustion is performed. Thereby, irregular combustion such as early ignition and misfire of the air-fuel mixture can be prevented.

  (5) The optimal combustion timing may be determined based on nitrogen oxides contained in the exhaust gas discharged from the cylinder, the maximum value of the rate of change of pressure in the cylinder, and the combustion stability of the air-fuel mixture.

  In this case, self-ignition combustion with good combustion stability and reduced nitrogen oxides, hammering sound and knocking becomes possible.

  (6) The engine system includes an intake passage that introduces air into the cylinder as intake air, a recirculation passage that introduces at least part of the exhaust discharged from the cylinder into the cylinder as intake air, and an air passage that is introduced into the cylinder through the intake passage. Information on the amount of exhaust and the amount of exhaust guided to the cylinder through the recirculation passage, the amount of exhaust adjusting means for adjusting the amount of exhaust discharged from the cylinder, and information on the operating state of the machine Driving information detecting means for detecting the control information, and the control means controls at least one of the intake air amount adjusting means and the exhaust gas amount adjusting means based on the information on the operating state detected by the operating information detecting means, Before self-ignition combustion, the amount of air that is guided into the cylinder through the intake passage and into the cylinder through the recirculation passage It controls the amount and the amount of burned gas remaining in the cylinder of the exhaust gas, the air-fuel ratio of the mixture may be set to the stoichiometric air-fuel ratio.

  In this engine system, at least a part of the burned gas in the cylinder is discharged from the cylinder as exhaust gas after the self-ignition combustion of the air-fuel mixture. At this time, the amount of exhaust discharged from the cylinder is adjusted by the exhaust amount adjusting means. Then, air is introduced into the cylinder through the intake passage, and at least a part of the exhaust discharged from the cylinder is introduced into the cylinder through the recirculation passage. At this time, at least one of the amount of air guided into the cylinder through the intake passage and the amount of exhaust guided into the cylinder through the recirculation passage is adjusted by the intake amount adjusting means.

  Thereafter, the air introduced into the cylinder through the intake passage, the exhaust introduced into the cylinder through the recirculation passage, and the burned gas remaining in the cylinder are compressed in the cylinder. As a result, the inside of the cylinder becomes a high-temperature and high-pressure state, and the air-fuel mixture composed of air and fuel is self-ignited and combusted.

  In this case, information related to the operating state of the mechanical device is detected by the operation information detecting means, and at least one of the intake air amount adjusting means and the exhaust air amount adjusting means is controlled by the control means based on the detected information. Thereby, before the self-ignition combustion, the amount of air guided into the cylinder through the intake passage, the amount of exhaust gas guided into the cylinder through the recirculation passage, and the amount of burned gas remaining in the cylinder are controlled.

  The burned gas remaining in the cylinder is in a high temperature state immediately after combustion. On the other hand, the exhaust gas introduced into the cylinder through the recirculation passage is at a lower temperature than the burned gas remaining in the cylinder.

  Therefore, by controlling the amount of burned gas remaining in the cylinder and the amount of exhaust gas introduced into the cylinder through the recirculation passage, the inside of the cylinder can be controlled to an optimum temperature. Thereby, the self-ignition timing of the air-fuel mixture can be easily adjusted. As a result, thermal efficiency is improved and stable self-ignition combustion can be performed.

  Further, the air-fuel ratio of the air-fuel mixture in the cylinder is set to the stoichiometric air-fuel ratio. In this case, the oxygen concentration in the burned gas generated by the self-ignition combustion of the air-fuel mixture becomes almost zero. That is, the oxygen concentration in the exhaust discharged from the cylinder becomes almost zero. Therefore, by using a catalyst, it becomes possible to sufficiently reduce nitrogen oxides in the exhaust gas, and the amount of nitrogen oxides in the exhaust gas can be reduced. As a result, it is possible to expand the operation range by self-ignition combustion while suppressing an increase in the amount of nitrogen oxides in the exhaust gas.

  (7) The intake air amount adjusting unit includes a first intake air amount adjusting unit that adjusts the flow rate in the intake passage, and a second intake air amount adjusting unit that adjusts the flow rate in the recirculation passage. By controlling at least one of the first intake air amount adjusting means, the second intake air amount adjusting means, and the exhaust air amount adjusting means based on the information on the operation state detected by the operation information detecting means, the self-ignition combustion is performed. In addition, the amount of air guided into the cylinder through the intake passage, the amount of exhaust guided into the cylinder through the recirculation passage, and the amount of burned gas remaining in the cylinder may be controlled.

  In this case, the amount of air guided into the cylinder through the intake passage is adjusted by the first intake air amount adjusting means, and the amount of exhaust gas guided into the cylinder through the recirculation passage is adjusted by the second intake air amount adjusting means. . By controlling at least one of the first intake air amount adjusting means, the second intake air amount adjusting means, and the exhaust air amount adjusting means, the amount of air guided into the cylinder through the intake passage, and into the cylinder through the recirculation passage. The amount of exhausted gas and the amount of burned gas remaining in the cylinder are controlled. Thereby, the temperature in the cylinder is controlled. As a result, the timing of the self-ignition combustion of the air-fuel mixture can be easily adjusted.

  (8) The intake air amount adjusting means includes third intake air amount adjusting means for adjusting the amount of intake air including the air guided into the cylinder through the intake passage and the exhaust gas guided into the cylinder through the recirculation passage, and the control means Is configured to control at least one of the third intake air amount adjusting unit and the exhaust gas amount adjusting unit based on the information on the operation state detected by the operation information detecting unit, so that the self-ignition combustion is performed in the cylinder through the intake passage. The amount of air introduced to the cylinder, the amount of exhaust introduced into the cylinder through the recirculation passage, and the amount of burned gas remaining in the cylinder may be controlled.

  In this case, the amount of intake air including the air guided into the cylinder through the intake passage introduced into the cylinder and the exhaust guided into the cylinder through the recirculation passage is adjusted by the third intake air amount adjusting means. By controlling at least one of the third intake amount adjusting means and the exhaust amount adjusting means, the amount of air guided into the cylinder through the intake passage, the amount of exhaust guided into the cylinder through the recirculation passage, and the inside of the cylinder The amount of remaining burnt gas is controlled. Thereby, the temperature in the cylinder is controlled. As a result, the timing of the self-ignition combustion of the air-fuel mixture can be easily adjusted.

  (9) The intake air amount adjusting means is guided into the cylinder through the first intake air amount adjusting means for adjusting the flow rate in the intake passage, the second intake air amount adjusting means for adjusting the flow rate in the recirculation passage, and the intake passage. And a third intake air amount adjusting means for adjusting the amount of intake air including the air to be discharged and the exhaust gas introduced into the cylinder through the recirculation passage, and the control means is based on the information on the operating state detected by the operating information detecting means. By controlling at least one of the first intake air amount adjusting means, the second intake air amount adjusting means, the third intake air amount adjusting means, and the exhaust air amount adjusting means, the cylinder is passed through the intake passage before the self-ignition combustion. The amount of air introduced into the interior, the amount of exhaust introduced into the cylinder through the recirculation passage, and the amount of burned gas remaining in the cylinder may be controlled.

  In this case, air that is guided into the cylinder through the intake passage is controlled by controlling at least one of the first intake air amount adjusting unit, the second intake air amount adjusting unit, the third intake air amount adjusting unit, and the exhaust air amount adjusting unit. , The amount of exhaust introduced into the cylinder through the recirculation passage, and the amount of burned gas remaining in the cylinder. Thereby, the temperature in the cylinder is controlled more accurately. As a result, the timing of the self-ignition combustion of the air-fuel mixture can be easily adjusted.

  (10) A vehicle according to a second invention includes the engine system according to the first invention and a transmission mechanism that transmits power generated by the engine system to drive wheels.

  In the vehicle according to the present invention, the power generated by the engine system according to the first invention is transmitted to the drive wheels by the transmission mechanism, and the drive wheels are driven.

  In this case, the combustion timing of the air-fuel mixture is prevented from being shortened even if the engine operates at a high speed because the combustion timing is retarded as the engine speed increases by the engine system according to the first aspect of the invention. The As a result, even when the engine is operating at a high speed, stable self-ignition combustion in which hitting sound and knocking are prevented can be achieved, and damage to the engine can be prevented.

  According to the present invention, since the combustion timing is retarded as the engine speed increases, the combustion period of the air-fuel mixture is prevented from being shortened even when the engine operates at a high speed. As a result, even when the engine is operating at a high speed, stable self-ignition combustion in which hitting sound and knocking are prevented can be achieved, and damage to the engine can be prevented.

  Hereinafter, an engine system according to an embodiment of the present invention will be described with reference to the drawings. The engine system according to the present embodiment performs combustion by an HCCI (Homogeneous-Charge Compression-Ignition combustion) method and a spark ignition method.

(1) Configuration of Engine System FIG. 1 is a schematic diagram showing an engine system according to an embodiment of the present invention. As shown in FIG. 1, the engine system 200 includes an ECU 50 (Electronic Control Unit), an engine 100, an intake pipe 11, an exhaust pipe 12, and an exhaust recirculation device 13.

  The engine 100 has a cylinder 1, and a piston 2 is provided in the cylinder 1 so as to be movable up and down. A combustion chamber 3 is provided in the upper part of the cylinder 1. The combustion chamber 3 communicates with the outside of the engine 100 via the intake port 4 and the exhaust port 5. An intake valve 6 is disposed at the intake port of the combustion chamber 3 so as to be freely opened and closed, and an exhaust valve 7 is disposed at the exhaust port of the combustion chamber 3 so as to be freely opened and closed. An intake valve driving device 6 a for driving the intake valve 6 is provided at the upper end of the intake valve 6. An exhaust valve driving device 7 a for driving the exhaust valve 7 is provided at the upper end of the exhaust valve 7. An ignition plug 8 for performing spark ignition in the combustion chamber 3 is provided on the upper portion of the combustion chamber 3.

  The cylinder 1 is provided with an injector 9 for injecting fuel into the cylinder 1 and a combustion timing measuring device 10 for measuring the combustion timing of the air-fuel mixture in the cylinder 1.

  An intake pipe 11 is attached to the engine 100 so as to communicate with the intake port 4, and an exhaust pipe 12 is attached so as to communicate with the exhaust port 5. An exhaust gas recirculation device 13 is provided in the intake pipe 11 and the exhaust pipe 12. The exhaust gas recirculation device 13 includes a pipe 13a for communicating the intake pipe 11 and the exhaust pipe 12, and an exhaust gas recirculation valve 13b provided in the pipe 13a.

  When the engine 100 is operated, air is sucked into the cylinder 1 from the intake port 4 through the intake pipe 11. Burned gas generated by the combustion of the air-fuel mixture in the cylinder 1 is discharged from the exhaust port 5 through the exhaust pipe 12. At this time, at least a part of the exhaust gas passing through the exhaust pipe 12 is guided to the intake pipe 11 by the exhaust gas recirculation device 13. The flow rate of the exhaust led from the exhaust pipe 12 to the intake pipe 11 is adjusted by the exhaust gas recirculation valve 13b.

  In addition, a throttle valve 14 is provided in the intake pipe 11 on the upstream side of the junction with the pipe 13a. By operating an accelerator (not shown), the opening of the throttle valve 14 is adjusted directly or indirectly. Thereby, the flow rate of air is adjusted. In the present embodiment, the driver can determine the required torque by adjusting the amount of operation of the accelerator (hereinafter referred to as accelerator opening). Therefore, when it is desired to increase the torque of engine 100, that is, during high load operation, the accelerator opening is increased, and when it is desired to decrease the torque of engine 100, that is, during low and medium load operation, the accelerator opening is decreased. In the present embodiment, the opening degree of the throttle valve 14 is also adjusted by the ECU 50.

  The ECU 50 includes an operation region determination unit 51, a spark ignition combustion control unit 52, an HCCI combustion control unit 53, a fuel property determination unit 54, and a storage unit 55. In addition, in FIG. 1, ECU50 is shown by the block diagram which shows a functional structure. The operation region determination unit 51, the spark ignition combustion control unit 52, the HCCI combustion control unit 53, the fuel property determination unit 54, and the storage unit 55 may be realized by a microcomputer and its control program, and some of these functional units. Alternatively, all may be realized by hardware such as an electronic circuit.

  The ECU 50 is given an engine speed ER from the engine speed sensor 31, an accelerator opening AO from the accelerator opening sensor 32, an oil temperature OT from the oil temperature sensor 33, and a water temperature WT from the water temperature sensor 34. And the combustion timing BP is given from the combustion timing measuring instrument 10. The ECU 50 is given a throttle opening TO from a throttle opening sensor (not shown). The throttle opening TO indicates the opening angle of the throttle valve 14.

  The ECU 50 provides the intake valve drive device 6a with the intake valve control signal IV, the exhaust valve drive device 7a with the exhaust valve control signal EV, the exhaust gas recirculation valve 13b with the exhaust gas recirculation valve control signal EGR, and the spark plug 8 Is given an ignition signal SI, an injection control signal FI is given to the injector 9, and a throttle valve control signal TV is given to the throttle valve 14. Thus, the ECU 50 controls the intake valve driving device 6a, the exhaust valve driving device 7a, the spark plug 8, the injector 9, the exhaust gas recirculation valve 13b, and the throttle valve 14.

(2) Engine Operation Next, the operation of the engine 100 will be described. In the present embodiment, combustion by the HCCI method (hereinafter referred to as HCCI combustion) and combustion by the spark ignition method (hereinafter referred to as spark ignition combustion) are selectively performed according to the designated load region. The operation of the engine 100 is controlled by the ECU 50. Hereinafter, the spark ignition combustion, the HCCI combustion, and the control operation by the ECU 50 will be described.

(2-1) Spark Ignition Combustion First, spark ignition combustion will be described. FIG. 2 is a diagram for explaining the operation of spark ignition combustion of engine 100.

  As shown in FIG. 2A, the intake valve 6 closes the intake port, the exhaust valve 7 lifts downward, and the piston 2 moves from approximately BDC (Bottom Dead Center) to approximately TDC (Top Ascends to Dead Center. Thereby, the burned gas in the cylinder 1 is discharged from the exhaust port 5. Hereinafter, the stroke shown in FIG. 2A is referred to as an exhaust stroke.

  Next, as shown in FIG. 2B, the exhaust valve 7 closes the exhaust port, the intake valve 6 is lifted downward, and the piston 2 is lowered from about TDC to about BDC. Thereby, air is sucked into the cylinder 1 from the intake port 4.

  At this time, fuel is injected into the cylinder 1 by the injector 9, and an air-fuel mixture comprising air and fuel is formed. Hereinafter, the stroke shown in FIG. 2B is referred to as an intake stroke.

  Here, in the spark ignition combustion, a period is provided in which both the intake valve 6 and the exhaust valve 7 are in a lifted state when shifting from the exhaust stroke of FIG. 2A to the intake stroke of FIG. 2B. . Such a period is generally called an overlap period.

  Next, as shown in FIG. 2 (c), with the intake port and the exhaust port closed, the piston 2 rises and the air-fuel mixture in the cylinder 1 is compressed. Hereinafter, the above-described process illustrated in FIG. 2C is referred to as a compression process.

  Next, as shown in FIG. 2D, in a state where the piston 2 rises to near TDC and the air-fuel mixture in the cylinder 1 is sufficiently compressed, sparks are generated in the air-fuel mixture in the cylinder 1 by the spark plug 8. Ignited. Thereby, the air-fuel mixture in the cylinder 1 burns. The piston 2 is driven downward by the combustion energy. Hereinafter, the stroke shown in FIG. 2D is referred to as a combustion stroke.

  After the piston 2 descends to approximately BDC, the process proceeds to the exhaust stroke shown in FIG. 2 (a), and the combustion stroke shown in FIG. 2 (d) is repeated from the exhaust stroke shown in FIG. 2 (a).

(2-2) HCCI combustion Next, HCCI combustion will be described. FIG. 3 is a diagram for explaining the operation of HCCI combustion of engine 100.

  As shown in FIG. 3A, the intake valve 6 closes the intake port, the exhaust valve 7 lifts downward, and the piston 2 rises from approximately BDC. Thereby, the burned gas in the cylinder 1 is discharged from the exhaust port 5. The stroke shown in FIG. 3A is called an exhaust stroke, like the stroke shown in FIG.

  Here, in HCCI combustion, as shown in FIG. 3B, the exhaust valve 7 is exhausted before the piston 2 rises to the TDC of the cylinder 1, that is, in a state where the burned gas remains in the cylinder 1. Close the mouth. For this reason, the burned gas in the cylinder 1 is compressed when the piston 2 rises to approximately TDC.

  At this time, fuel is injected into the burned gas in the cylinder 1 by the injector 9. Since the burned gas in the cylinder 1 is compressed by the piston 2, it is in a high temperature and high pressure state. As a result, the fuel injected into the burned gas undergoes a reaction under high temperature and pressure, and is reformed into a highly reactive state. Hereinafter, as shown in FIG. 3B, the above-described period in which both the intake port and the exhaust port are closed after the exhaust stroke is referred to as a sealed period. Further, the fuel reaction in the sealed period is called a fuel pre-reaction.

  Next, as shown in FIG. 3C, the piston 2 descends from about TDC, and the intake valve 6 lifts downward. For this reason, intake air is drawn into the cylinder 1 from the intake port 4. Here, the intake air includes air guided to the intake port 4 through the intake pipe 11 and exhaust gas (hereinafter referred to as recirculated exhaust gas) guided from the exhaust pipe 12 into the intake pipe 11 through the pipe 13a. Thereby, an air-fuel mixture composed of air and fuel is formed in the cylinder 1. The stroke shown in FIG. 3C is called an intake stroke, similar to the stroke shown in FIG. Thereafter, the piston 2 descends to approximately BDC, and the intake valve 6 closes the intake port.

  Next, as shown in FIG. 3 (d), with the intake port and the exhaust port closed, the piston 2 rises and the air-fuel mixture in the cylinder 1 is compressed. The stroke shown in FIG. 3D is referred to as a compression stroke, similar to the stroke shown in FIG.

  Next, as shown in FIG. 3E, when the piston 2 rises to the vicinity of TDC and the air-fuel mixture in the cylinder 1 is sufficiently compressed, self-ignition occurs in the air-fuel mixture. At this time, self-ignition occurs almost simultaneously at a plurality of locations in the combustion chamber 3. Thereby, the air-fuel mixture in the combustion chamber 3 burns instantaneously. The piston 2 is driven downward by the combustion energy. The stroke shown in FIG. 3 (e) is called a combustion stroke, similar to the stroke shown in FIG. 2 (d).

  In particular, in this example, since the sealing period of FIG. 3B is provided, burned gas that is in a high temperature state after combustion remains in the cylinder 1. Thereby, the temperature of the air-fuel mixture in the cylinder 1 becomes higher than that in the case of spark ignition combustion. Further, during the sealing period, the fuel in the cylinder 1 is reformed to a highly reactive state. As a result, self-ignition easily occurs in the combustion stroke of FIG.

  After the piston 2 descends to approximately BDC, the process proceeds to the exhaust stroke shown in FIG. 3 (a), and the combustion stroke shown in FIG. 3 (e) is repeated from the exhaust stroke shown in FIG. 3 (a).

  Thus, in the HCCI combustion, unlike the spark ignition combustion described above, both the intake port and the exhaust port are closed between the exhaust stroke of FIG. 3A and the intake stroke of FIG. 3C. A sealing period of 3 (b) is provided.

  In the spark ignition combustion, air is sucked into the cylinder 1 from the intake port 4 and fuel is injected into the cylinder 1 by the injector 9 in the intake stroke of FIG. Is formed. On the other hand, in the HCCI combustion, after the fuel is injected into the cylinder 1 by the injector 9 in the sealing period of FIG. 3B, the intake air including the air and the recirculated exhaust is injected into the cylinder in the intake stroke of FIG. 1 is inhaled. As a result, in the cylinder 1, a mixture of air and fuel, recirculation exhaust, and burned gas are mixed.

(2-3) Valve Lift during Spark Ignition Combustion and HCCI Combustion FIG. 4 is a diagram showing valve lift amounts of the intake valve 6 and the exhaust valve 7 in each stroke of the spark ignition combustion of FIG. 2 and the HCCI combustion of FIG. It is. FIG. 4A shows a case where the maximum value of the valve lift amount in HCCI combustion is equal to the maximum value of the valve lift amount in spark ignition combustion, and FIG. 4B shows the maximum valve lift amount in HCCI combustion. This shows a case where the value and the maximum value of the valve lift amount in spark ignition combustion are different.

  In FIG. 4, the vertical axis represents the valve lift amount, and the horizontal axis represents the crank angle. A curve a1 represents the valve lift amount of the exhaust valve 7 in spark ignition combustion, and a curve a2 represents the valve lift amount of the intake valve 6 in spark ignition combustion. A curve b1 indicates the valve lift amount of the exhaust valve 7 in HCCI combustion, and a curve b2 indicates the valve lift amount of the intake valve 6 in HCCI combustion.

  In FIG. 4, the period of each stroke in the spark ignition combustion is indicated by a solid arrow, and the period of each stroke in the HCCI combustion is indicated by a dotted arrow.

  As shown in FIG. 4A, in the spark ignition combustion, there is no sealing period in which the lift amounts of the intake valve 6 and the exhaust valve 7 are both zero between the exhaust stroke and the intake stroke. Before the lift amount becomes zero, the lift amount of the intake valve 6 becomes a positive value. That is, the lift amounts of the intake valve 6 and the exhaust valve 7 are both positive in the vicinity of the TDC.

  In HCCI combustion, the lift amount of the exhaust valve 7 takes a positive value during the exhaust stroke, and the lift amount of the intake valve 6 takes a positive value during the intake stroke. During the sealing period between the exhaust stroke and the intake stroke, the lift amounts of the intake valve 6 and the exhaust valve 7 are zero.

  In the compression stroke after the intake stroke, the lift amounts of the intake valve 6 and the exhaust valve 7 are both 0, and the combustion stroke is entered in the vicinity of the TDC.

  In the example shown in FIG. 4B, the intake valve 6 and the exhaust valve 7 are driven so that the valve lift amount in HCCI combustion is smaller than the valve lift amount in spark ignition combustion.

  In this case, when the engine 100 performs the HCCI combustion during the middle / low load operation, the amount of intake air sucked into the cylinder 1 and discharged from the cylinder 1 is compared with that during the high load operation where the engine 100 performs the spark ignition combustion. The amount of exhaust is reduced.

  As a device for switching the valve lift amount according to the load of the engine 100, for example, a cam switching mechanism that switches between two types of cams for high load and low load with different cam nose lengths according to the load, or electromagnetic force An electromagnetically driven valve that controls opening and closing of the intake valve 6 and the exhaust valve 7 is used.

(2-4) Control Operation by ECU Next, the control operation of the ECU 50 in FIG. 1 will be described.

  FIG. 5 is a flowchart showing the control operation of the ECU 50.

  First, as shown in FIG. 5, the ECU 50 acquires driving information (step S1). Here, the operation information is information related to the operating state of the engine system 200. For example, the accelerator opening AO, the engine speed ER, the oil temperature OT, the water temperature WT, the injection control signal FI, the throttle opening TO, the intake valve 6 and the opening / closing timing of the exhaust valve 7 and the opening degree of the exhaust gas recirculation valve 13b.

  Next, the driving region determination unit 51 of the ECU 50 determines whether or not the accelerator opening AO acquired in step S1 is within a specified range (step S2). The specified range used in step S2 can be arbitrarily determined so that engine 100 can perform stable HCCI combustion.

  When the accelerator opening AO is within the specified range, the HCCI combustion control unit 53 of the ECU 50 performs the HCCI combustion process (step S3). Then, it returns to step S1.

  In step S2, if the accelerator opening AO is outside the specified range, the spark ignition combustion control unit 52 of the ECU 50 performs a spark ignition combustion process (step S4). In this case, the spark ignition combustion is controlled by a normal stoichiometric air-fuel ratio. Then, it returns to step S1.

  Hereinafter, the HCCI combustion process in step S3 will be described in more detail. In the present embodiment, a target combustion timing (hereinafter referred to as target combustion timing) is determined in advance according to the rotational speed of engine 100, and combustion timing BP detected by combustion timing measuring instrument 10 is the target. Each part is controlled to be equal to the combustion timing. The target combustion timing is stored in the storage unit 55 (see FIG. 1).

  First, the combustion timing BP and the target combustion timing will be described.

  As described above, the combustion timing BP is detected by the combustion timing measuring instrument 10. For example, the combustion time BP is the time when the heat generation rate in the cylinder 1 is maximized (the time when dQ / dθ is maximized), or the time when the rate of change of the pressure in the cylinder 1 due to combustion is maximized (dP / dθ). Can be detected as any one of the periods when becomes the maximum. Q indicates the amount of heat generated in the cylinder 1, P indicates the pressure in the cylinder 1, and θ indicates the crank angle.

  Further, a time when the combustion mass ratio becomes 50% may be used as the combustion time BP. FIG. 6 shows an example of the relationship between the crank angle and the heat generation rate in the cylinder 1 and the relationship between the crank angle and the fuel mass ratio. The timing when the combustion mass ratio becomes 50% is slightly retarded as compared with the time when dP / dθ is maximum, but as shown in FIG. 6, the timing when the combustion mass ratio becomes 50% and dQ / The time when dθ is maximized is almost the same. Therefore, the time when the combustion mass ratio becomes 50% may be set as the combustion time BP.

  Further, when the ion current in one cycle of engine 100 is integrated, the time when the integrated value becomes 50% is almost the same as the time when the combustion mass ratio becomes 50%. % May be the combustion timing BP.

  In the present embodiment, as the combustion timing measuring instrument 10, for example, an apparatus that can measure an ion current using an ion probe or the like is used. And the time of 50% of the integrated value of the measured ion current is set as the combustion time BP.

Here, the present inventors have found that by various experiments or the like, combustion timing relationship between BP and NO _X, the relationship between the change rate of the pressure of the cylinder 1 due to combustion and combustion timing BP, and combustion timing BP and combustion The relationship with stability was derived as follows.

FIG. 7 is a diagram showing the relationship between the combustion timing BP and NO _x exhausted from the engine 100 when the engine 100 is operating at a certain rotational speed. In FIG. 7, the horizontal axis indicates the combustion timing BP, and the vertical axis indicates the amount of NO _x discharged. As shown in FIG. 7, the amount of NO _x discharged from the engine 100 is large when the combustion timing BP is in the vicinity of the compression top dead center, and decreases as it becomes retarded from the compression top dead center. . In other words, by setting the combustion timing BP retarded, it can be seen that can reduce the NO _X discharged from the engine 100.

  FIG. 8 is a diagram showing the relationship between the combustion timing BP and the maximum value of the rate of change of pressure in the cylinder 1 when the engine 100 is operating at a certain rotational speed. In FIG. 8, the horizontal axis represents the combustion timing BP, and the vertical axis represents the maximum value of the rate of change of pressure in the cylinder 1. As shown in FIG. 8, the maximum value of the change rate of the pressure in the cylinder 1 is large when the combustion timing BP is near the compression top dead center, and decreases as the compression top dead center is retarded. Yes. Here, in order to reduce the hitting sound and knocking due to combustion, it is necessary to reduce the maximum value of the rate of change of the pressure in the cylinder 1. That is, by setting the combustion timing BP to the retard side, it is possible to reduce the hitting sound and knocking caused by the combustion.

  FIG. 9 is a diagram showing the relationship between the combustion timing BP and the combustion stability when the engine 100 is operating at a certain rotational speed. In FIG. 9, the horizontal axis represents the combustion timing BP, and the vertical axis represents the combustion stability. As shown in FIG. 9, the combustion stability is poor when the combustion timing BP is in the vicinity of the compression top dead center, and becomes better as the combustion timing BP is retarded from the compression top dead center. It gets worse again when it comes to the side. The combustion stability can be calculated based on, for example, the fluctuation rate of the indicated thermal efficiency or the fluctuation rate of the peak value of the pressure in the cylinder 1, but is not limited to this, and the combustion stability can be calculated based on other factors. Stability may be calculated.

In the present embodiment, in consideration of the relationships shown in FIGS. 7 to 9, the optimum target combustion timing is determined so that the combustion stability is good and NO _x , sound and knocking can be reduced. To do.

  In the present embodiment, the target combustion timing is changed according to the rotational speed of engine 100 so that the time from compression top dead center to target combustion timing is constant. In this case, the target combustion timing changes to the retard side as the engine speed increases as shown in FIG.

  That is, in the present embodiment, first, a basic target combustion timing is determined at an arbitrary number of revolutions of engine 100, and a time from the compression top dead center to the target combustion timing is calculated. Then, the target combustion timing corresponding to the rotational speed of engine 100 is determined so that the time from the calculated compression top dead center to the target combustion timing is maintained. Here, the combustion stability in the HCCI combustion is greatly influenced by the temperature and pressure in the cylinder 1 and the holding time thereof. Therefore, it is possible to always obtain good combustion stability by always controlling the time from the compression top dead center to the target combustion timing to be constant as in the present embodiment. The basic target combustion timing is preferably obtained, for example, at the rotational speed at which engine 100 is used most frequently.

  Next, the control operation of the ECU 50 during the HCCI combustion process will be described.

  FIG. 11 is a flowchart showing details of the HCCI combustion process shown in step S3 of FIG.

  As shown in FIG. 11, the HCCI combustion control unit 53 (see FIG. 1) of the ECU 50 reads from the storage unit 55 the target combustion timing according to the engine speed ER (operation information) acquired in step S1 of FIG. (Step S11).

  Next, the HCCI combustion control unit 53 determines the fuel injection amount and the air amount based on the operation information acquired in step S1 of FIG. 5 (step S12). The amount of air is determined so that the air-fuel ratio of the air-fuel mixture becomes the stoichiometric air-fuel ratio (about 14.5: 1).

  Next, the HCCI combustion control unit 53 determines the burned gas amount and the recirculated exhaust amount based on the target combustion timing read in step S11 and the air amount determined in step S12 (step S13). In this process, the temperature in the cylinder 1 can be adjusted by adjusting the burnt gas amount and the recirculation exhaust amount. Details will be described later.

  Next, the HCCI combustion control unit 53 determines whether or not a correction coefficient has been calculated in the process one cycle before (step S14). The correction coefficient is calculated in the process of step S20 described later.

  When the correction coefficient is calculated, the HCCI combustion control unit 53 multiplies the burned gas amount and the recirculated exhaust gas amount determined in step S13 by the correction coefficient (step S15).

  Next, the HCCI combustion control unit 53 determines the opening / closing timing of the intake valve 6 and the exhaust gas based on the fuel injection amount and air amount determined in step S12 and the burned gas amount and recirculation exhaust amount calculated in step S15. The opening / closing timing of the valve 7, the opening degree of the exhaust gas recirculation valve 13b, and the opening degree of the throttle valve 14 are determined (step S16). When the correction coefficient is not calculated in step S14, the intake valve 6 is based on the fuel injection amount and air amount determined in step S12 and the burned gas amount and recirculation exhaust amount determined in step S13. Open / close timing, exhaust valve 7 open / close timing, exhaust recirculation valve 13b opening, and throttle valve 14 opening are determined.

  Next, the HCCI combustion control unit 53 performs mixing based on the opening / closing timing of the intake valve 6, the opening / closing timing of the exhaust valve 7, the opening degree of the exhaust recirculation valve 13b, and the opening degree of the throttle valve 14 determined in step S16. While the self-ignition combustion is performed, the actual combustion timing BP is acquired from the combustion timing measuring instrument 10 (step S17).

  Next, the HCCI combustion control unit 53 calculates an error between the target combustion timing read in step S11 and the actual combustion timing BP acquired in step S16 (step S18). Next, the HCCI combustion control unit 53 determines whether or not the absolute value of the error calculated in step S18 is greater than or equal to a preset threshold value (step S19).

  When the absolute value of the error is less than or equal to the threshold value, the HCCI combustion control unit 53 calculates a correction coefficient for the recirculated exhaust gas amount and the burned gas amount (step S20). Thereafter, the HCCI combustion control unit 53 returns to step S1 in FIG.

  If the absolute value of the error is larger than the threshold value in step S19, the spark ignition combustion control unit 52 (see FIG. 1) performs a spark ignition combustion process (step S21). Then, it returns to step S1 of FIG. By providing the processing of step S19 and step S21, when the actual combustion timing BP is greatly different from the target combustion timing, spark ignition combustion can be performed without performing HCCI combustion. Thereby, irregular combustion such as early ignition and misfire of the air-fuel mixture can be prevented.

  Note that the correction coefficient for the recirculated exhaust gas amount and the burned gas amount calculated in step S20 is calculated so that the error between the target combustion timing and the actual combustion timing BP becomes small. Specifically, when the actual combustion timing is later than the target combustion timing, the ratio of burned gas to the recirculated exhaust is increased, and when the actual combustion timing is earlier than the target combustion timing, A correction coefficient is calculated so as to increase the ratio of recirculation exhaust.

  Here, the combustion timing depends on the temperature in the cylinder 1, and the combustion timing becomes earlier as the temperature in the cylinder 1 becomes higher.

  The burned gas remaining in the cylinder 1 is in a high temperature state immediately after combustion. On the other hand, the intake air sucked into the cylinder 1 from the intake port 4 is the air sucked into the cylinder 1 from the intake port 4 through the intake pipe 11 and the recirculated exhaust gas sucked into the cylinder 1 through the exhaust gas recirculation device 13. including. Since the exhaust gas has been exhausted for a predetermined time from the combustion stroke, it has a lower temperature than the burned gas.

  In the present embodiment, the temperature in the cylinder 1 can be adjusted by adjusting the ratio of the air amount, the burned gas amount, and the recirculation exhaust amount. The amount of air is determined so that the air-fuel mixture becomes the stoichiometric air-fuel ratio, and the intake valve 6, the exhaust valve 7, and the exhaust gas are optimized so that the burned gas amount and the recirculated exhaust amount are optimized with respect to the determined air amount. By controlling the recirculation valve 13b and the throttle valve 14, the temperature in the cylinder 1 can be adjusted. As a result, the combustion timing in the cylinder 1 can be adjusted.

  A temperature sensor for detecting the temperature of the burned gas remaining in the cylinder 1 and a temperature sensor for detecting the temperature of the intake air introduced into the cylinder 1 may be provided at predetermined positions. In this case, the ECU 50 can determine the ratio between the burned gas amount and the intake air amount based on the temperature detected by the temperature sensor. Thereby, the temperature in the cylinder 1 can be adjusted more accurately.

  Also, a temperature sensor for detecting the temperature of air sucked into the cylinder 1 from the intake pipe 11 and a temperature sensor for detecting the temperature of exhaust gas sucked into the cylinder 1 by the exhaust gas recirculation device 13 are separated. May be provided. In this case, the temperature in the cylinder 1 can be adjusted more accurately.

(2-5) Setting of the theoretical air-fuel ratio As described above, in the present embodiment, the amount of air in the cylinder 1 is determined in step S12 so that the air-fuel ratio in the cylinder 1 becomes the stoichiometric air-fuel ratio in HCCI combustion. ing. The reason for this will be described below.

  First, the relationship between the thermal efficiency in the case of performing HCCI combustion and the oxygen concentration in the cylinder 1 during the sealing period will be described.

  FIG. 12 is a diagram showing the relationship between the oxygen concentration and the heat generation amount during the sealing period. In FIG. 12, the horizontal axis indicates the oxygen concentration in the burned gas in the cylinder 1, and the vertical axis indicates the heat generation amount during the sealing period.

  In the sealed period, as shown in FIG. 3B, fuel pre-reaction occurs in the sealed cylinder 1. Thereby, reaction heat is generated in the cylinder 1. Further, the increase in the oxygen concentration in the cylinder 1 facilitates the pre-reaction of fuel. Accordingly, as shown in FIG. 12, the amount of heat generated by the pre-reaction of the fuel increases as the oxygen concentration increases.

  FIG. 13 is a diagram showing the relationship between the crank angle and the pressure in the cylinder 1.

  In the sealing period, the compression stroke, and the combustion stroke, the lift amount of the intake valve 6 and the exhaust valve 7 becomes 0 as shown in FIGS. The intake port 4 and the exhaust port 5 are closed. Since the gas in the cylinder 1 is compressed by the piston 2, as shown in FIG. 13, the pressure in the cylinder 1 increases during the sealing period, the compression stroke, and the combustion stroke.

  As shown in FIG. 3, the position of the piston 2 when shifting from the exhaust stroke of FIG. 3 (a) to the sealing period of FIG. 3 (b) is from the intake stroke of FIG. 3 (c) to FIG. 3 (d). ) In the state closer to TDC than the position of the piston 2 when shifting to the compression stroke. Thereby, the pressure in the cylinder 1 in the sealing period becomes smaller than the pressure in the cylinder 1 in the compression stroke and the combustion stroke (hereinafter referred to as the compression combustion stroke). That is, the actual compression ratio in the cylinder 1 during the sealing period is smaller than the actual compression ratio in the cylinder 1 during the compression combustion stroke. Here, the actual compression ratio refers to the volume of the space formed above the piston 2 in the cylinder 1 when moving to the sealing period or the compression stroke, and the piston in the cylinder 1 when the piston 2 is located at TDC. 2 is a ratio with the volume of the space formed above 2 (the volume of the combustion chamber 3).

  As the actual compression ratio is reduced, the thermal efficiency is lowered, so that the thermal efficiency of the closed stroke is lower than the thermal efficiency of the compression combustion stroke.

  FIG. 14 is a diagram showing the relationship between the heat generation amount during the sealing period and the thermal efficiency in HCCI combustion.

  In the cylinder 1, heat is generated by the fuel pre-reaction in the closed period and the combustion of the air-fuel mixture in the combustion stroke. The piston 2 is driven by this heat. That is, the fuel injected into the cylinder 1 is converted into thermal energy by pre-reaction and combustion reaction, and this thermal energy performs work on the piston 2. At this time, the higher the thermal efficiency in the cylinder 1, the more work can be performed on the piston 2. That is, the higher the thermal efficiency of the engine 100, the larger the driving force of the piston 2 can be obtained.

  As described above, since the thermal efficiency of the compression combustion stroke is higher than that of the closed stroke, the piston 2 can obtain a driving force more efficiently from the thermal energy in the compression combustion stroke.

  Further, since the heat energy obtained from the fuel is constant, the sum of the heat generation amount due to the pre-reaction and the heat generation amount due to the combustion is constant.

  Therefore, as shown in FIG. 14, the heat generation amount during the sealing period increases, so that the thermal efficiency of the entire HCCI combustion including the sealing period and the compression combustion stroke decreases.

  As shown in FIG. 12, the heat generation amount during the sealing period increases as the oxygen concentration increases. Therefore, the thermal efficiency in HCCI combustion decreases as the oxygen concentration increases during the sealing period.

  In the present embodiment, the air-fuel ratio in the cylinder 1 in the compression combustion stroke is set to be the stoichiometric air-fuel ratio. In this case, almost all oxygen in the air is consumed by combustion. As a result, the oxygen concentration in the burned gas remaining in the cylinder 1 during the sealing period becomes substantially zero. Therefore, it is possible to prevent a decrease in thermal efficiency in HCCI combustion.

(2-6) Effects of the Present Embodiment As described above, in the engine system 200 according to the present embodiment, the target combustion timing is set and set so as to be retarded as the engine speed increases. Each part of the engine system 200 is controlled so that self-ignition combustion is performed at the target combustion timing. In this case, the combustion period of the air-fuel mixture is prevented from being shortened even when the engine 100 operates at a high speed. As a result, even when engine 100 is operating at a high speed, stable HCCI combustion in which hammering sound and knocking are prevented can be achieved, and damage to engine 100 can be prevented.

  Further, the target combustion timing is set so that the time from the compression top dead center to the target combustion timing is always constant. Thereby, it is possible to obtain good combustion stability in a wider range of operation.

  In the above embodiment, when it is desired to perform HCCI combustion in a wider range of operation, the designated range in step S2 in FIG.

  Further, in the HCCI combustion, the ECU 50 controls the intake valve drive device 6a, the exhaust valve drive device 7a, the exhaust gas recirculation valve 13b, and the throttle valve 14 so that the error between the target combustion timing and the actual combustion timing BP becomes small. . Thereby, the ratio of the burned gas amount and the recirculated exhaust amount is adjusted, and the temperature in the cylinder 1 is adjusted. Therefore, the optimal combustion time in HCCI combustion can be obtained. As a result, thermal efficiency is improved and stable HCCI combustion can be performed.

  In HCCI combustion, the air-fuel ratio in the cylinder 1 in the compression combustion stroke is set to be the stoichiometric air-fuel ratio. In this case, almost all oxygen in the air-fuel mixture is consumed by combustion. Thereby, the oxygen concentration in the burned gas remaining in the cylinder 1 during the sealing period becomes substantially zero. Therefore, it is possible to prevent a decrease in thermal efficiency in HCCI combustion.

Further, by performing HCCI combustion at the stoichiometric air-fuel ratio, the oxygen concentration in the exhaust discharged from the cylinder 1 becomes almost zero. Therefore, NO _x in the exhaust can be reduced by using the three-way catalyst. As a result, it becomes possible to expand the operation range by HCCI combustion.

  Further, in the present embodiment, air and recirculated exhaust are simultaneously sucked into the cylinder 1. Normally, the air amount is adjusted by the intake valve driving device 6a and the throttle valve 14, but in the case of the present embodiment, the recirculation exhaust amount is further adjusted by adjusting the flow rate of the recirculation exhaust gas by the exhaust gas recirculation valve 13b. The ratio of the air amount to can be adjusted more accurately.

(Configuration of the entire vehicle)
FIG. 15 is a schematic diagram of a motorcycle including the engine system 200 according to the above embodiment.

  In the motorcycle 600, a head pipe 602 is provided at the front end of the main body frame 601. A front fork 603 is provided on the head pipe 602 so as to be swingable in the left-right direction. A front wheel 604 is rotatably supported at the lower end of the front fork 603. A handle 605 is attached to the upper end of the head pipe 602.

  The engine system 200 of FIG. 1 is provided at the center of the main body frame 601. FIG. 15 shows the engine 100, the intake pipe 11, the exhaust pipe 12 and the exhaust gas recirculation device 13 included in the engine system 200. A fuel tank 606 is provided at the top of the engine system 200, and a seat 607 is provided behind the fuel tank 606.

  A rear arm 608 is connected to the main body frame 601 so as to extend rearward of the engine system 200. The rear arm 608 rotatably holds the rear wheel 609 and the rear wheel driven sprocket 610. A three-way catalyst 616 is inserted in the exhaust pipe 12 of the engine system 200, and a muffler 612 is attached to the rear end of the exhaust pipe 12.

  A drive shaft 613 is attached to the engine 100 of the engine system 200, and a rear wheel drive sprocket 614 is attached to the drive shaft 613. The rear wheel drive sprocket 614 is coupled to the rear wheel driven sprocket 610 via the chain 615.

  Since the motorcycle 600 includes the engine system 200 according to the above-described embodiment, even when the engine 100 is operating at a high speed, stable self-ignition combustion that prevents knocking and knocking is possible. In addition, the engine 100 can be prevented from being damaged.

  Further, the target combustion timing is set so that the time from the compression top dead center to the target combustion timing is always constant. Thereby, it becomes possible to always obtain good combustion stability.

  Further, the temperature in the cylinder 1 is adjusted in the HCCI combustion, and the optimum combustion time can be obtained. As a result, thermal efficiency is improved and stable HCCI combustion can be performed.

  Further, in the operation by HCCI combustion, the air-fuel ratio in the cylinder 1 in the compression combustion stroke is set to be the stoichiometric air-fuel ratio. In this case, almost all oxygen in the air-fuel mixture is consumed by combustion. Thereby, the oxygen concentration in the burned gas remaining in the cylinder 1 during the sealing period becomes substantially zero. Therefore, it is possible to prevent a decrease in thermal efficiency in HCCI combustion.

Further, by performing HCCI combustion at the stoichiometric air-fuel ratio, the oxygen concentration in the exhaust discharged from the cylinder 1 becomes almost zero. Therefore, NO _x in the exhaust can be reduced by using the three-way catalyst. As a result, it becomes possible to expand the operation range by HCCI combustion.

(Correspondence between each component of claim and each part of embodiment)
In the above embodiment, the motorcycle 600 corresponds to a mechanical device, the engine speed sensor 31 corresponds to a speed detection means, the ECU 50 corresponds to a control means, and the combustion timing measuring device 10 serves as a combustion timing measuring means. The storage unit 55 corresponds to storage means, and the spark plug 8 corresponds to ignition means.

  The intake pipe 11 corresponds to the intake passage, the pipe 13a corresponds to the recirculation passage, the intake valve 6, the intake valve drive device 6a, the exhaust recirculation valve 13b, and the throttle valve 14 correspond to the intake air amount adjusting means. The exhaust valve 7 and the exhaust valve driving device 7a correspond to the exhaust amount adjusting means, the operation information corresponds to information related to the operation state, the engine speed sensor 31, the accelerator opening sensor 32, the oil temperature sensor 33, the water temperature sensor 34, and The throttle opening sensor corresponds to the operation information detecting means, the throttle valve 14 corresponds to the first intake air amount adjusting means, the exhaust gas recirculation valve 13b corresponds to the second intake air amount adjusting means, the intake valve 6 and the intake air The valve driving device 6a corresponds to a third intake air amount adjusting means.

  The rear wheel 609 corresponds to a drive wheel, and the rear wheel driven sprocket 610, the drive shaft 613, the rear wheel drive sprocket 614, and the chain 615 correspond to a transmission mechanism.

(Modification)
In the above embodiment, the operation information includes the accelerator opening AO, the engine speed ER, the oil temperature OT, the water temperature WT, the injection control signal FI, the fuel amount, the throttle opening TO, the intake valve 6 and the exhaust valve 7. Any one or more of information such as opening / closing timing and the opening degree of the exhaust gas recirculation valve 13b may be acquired, or other information such as engine temperature or fuel type may be acquired as operation information. Good.

  In the above embodiment, the accelerator opening AO is used as a parameter for determining the load of the engine 100. However, the present invention is not limited to this, and other conditions such as the engine speed ER or the engine temperature may be used. . Also, the load on engine 100 may be determined using a plurality of these conditions.

  In step S2 in FIG. 5, it is determined whether to perform HCCI combustion or spark ignition combustion based on the accelerator opening AO (requested torque). Based on the load (torque), it may be determined whether to perform the HCCI combustion process or the spark ignition combustion process.

  Further, in step S2 of FIG. 5, it may be further determined whether to perform HCCI combustion processing or spark ignition combustion processing based on the rotational speed of engine 100, the warm-up state of engine 100, and the like.

  The exhaust gas recirculation device 13 may be provided with a cooling device for adjusting the temperature of the exhaust gas in the pipe 13a. In this case, the temperature of the exhaust gas contained in the intake air can be adjusted. Thereby, the temperature in the cylinder 1 can be adjusted more accurately.

  In the above embodiment, spark ignition by the spark plug 8 is not performed in the combustion stroke of HCCI combustion, but spark ignition by the spark plug 8 may be performed. Thereby, the ignition of fuel is more reliably performed in the combustion stroke.

  In the above embodiment, the amount of air sucked into the cylinder 1 is adjusted by the intake valve driving device 6a and the throttle valve 14, but is not limited to this, and other devices such as a supercharger are used. It may be used to adjust the amount of air.

  In the above embodiment, each functional unit of the ECUs 50 and 50a shown in FIG. 2 is realized by a program. However, part or all of each functional unit may be realized by hardware such as an electronic circuit.

  In the above-described embodiment, an in-cylinder fuel direct injection engine in which fuel is directly injected into the cylinder 1 is used. However, the present invention is not limited to this, and a structure in which fuel is injected into the intake port 4 is used. You may use the engine which has. In this case, fuel is not injected during the sealing period between the exhaust stroke and the intake stroke, so that no pre-reaction of fuel is performed.

  Further, in the compression stroke of HCCI combustion shown in FIG. 3D, the injector 9 may perform the second fuel injection.

  In the example of FIG. 15, the case where the engine system 200 of the above embodiment is applied to a motorcycle has been described. However, the engine system 200 is applied to other vehicles such as a four-wheeled vehicle, a ship, a generator, or the like. Also good.

  The present invention can be used for various vehicles, ships, generators and the like equipped with engines such as two-wheeled vehicles and four-wheeled vehicles.

It is a mimetic diagram showing an engine system concerning one embodiment of the present invention. It is a figure for demonstrating the operation | movement of the spark ignition combustion of an engine. It is a figure for demonstrating operation | movement of the HCCI combustion of an engine. FIG. 4 is a diagram showing valve lift amounts of intake valves and exhaust valves in each stroke of the spark ignition combustion of FIG. 2 and the HCCI combustion of FIG. 3. It is a flowchart which shows the control action of ECU. It is a figure which shows an example of the relationship between the crank angle in a cylinder, and a heat release rate. When operating at a constant rotational speed with the engine is a diagram showing a relationship between the NO _X discharged from the combustion timing and an engine. It is the figure which showed the relationship between a combustion time and the maximum value of the rate of change of the pressure in a cylinder when an engine is operate | moving with a fixed rotational speed. It is the figure which showed the relationship between a combustion time and combustion stability in case an engine is operate | moving with a fixed rotational speed. It is the figure which showed the relationship between an engine speed and target combustion time. It is a flowchart which shows the detail of the HCCI combustion process shown by step S3 of FIG. It is a figure which shows the relationship between the oxygen concentration and heat generation amount in a sealing period. It is a figure which shows the relationship between a crank angle and the pressure in a cylinder. It is a figure which shows the relationship between the heat generation amount in a sealing period, and the thermal efficiency in HCCI combustion. 1 is a schematic diagram of a motorcycle including an engine system according to the present embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Intake port 5 Exhaust port 6 Intake valve 6a Intake valve drive device 7 Exhaust valve 7a Exhaust valve drive device 8 Spark plug 9 Injector 10 Combustion timing measuring device 11 Intake pipe 12 Exhaust pipe 13 Exhaust gas recirculation device 13b Exhaust gas recirculation valve 14 Throttle valve 31 Engine speed sensor 32 Accelerator opening sensor 33 Oil temperature sensor 34 Water temperature sensor 50 ECU
DESCRIPTION OF SYMBOLS 100 Engine 200 Engine system 609 Rear wheel 610 Rear wheel driven sprocket 613 Drive shaft 614 Rear wheel drive sprocket 615 Chain 616 Three-way catalyst

Claims (10)

An engine system for driving a mechanical device,
An engine having a cylinder, and an air-fuel mixture in the cylinder performs self-ignition combustion;
A rotational speed detection means for detecting the rotational speed of the engine;
Control means for controlling the timing of self-ignition of the air-fuel mixture when the engine is performing self-ignition combustion,
The control means controls the timing of self-ignition of the air-fuel mixture so that the timing of self-ignition of the air-fuel mixture is retarded as the engine speed detected by the speed detection means increases. A featured engine system. The engine system according to claim 1, wherein the control means controls the timing of self-ignition of the air-fuel mixture so that the time from compression top dead center to self-ignition is always equal. Combustion timing measuring means for measuring the combustion timing of the mixture,
Storage means for storing an optimal combustion timing of the air-fuel mixture corresponding to the engine speed,
The control means controls the self-ignition timing of the air-fuel mixture so that an error between the combustion timing measured by the combustion timing measuring means and the optimum combustion timing stored in the storage means becomes small. The engine system according to claim 1 or 2, characterized in that Further comprising ignition means for spark ignition combustion of the air-fuel mixture,
The engine system according to claim 3, wherein the control means causes the air-fuel mixture to undergo spark ignition combustion by the ignition means when the absolute value of the error is larger than a predetermined value. The optimum combustion timing is determined based on nitrogen oxides contained in exhaust discharged from the cylinder, a maximum value of a rate of change in pressure in the cylinder, and combustion stability of the air-fuel mixture. The engine system according to claim 3 or 4. An intake passage for introducing air into the cylinder as intake air;
A recirculation passage for guiding at least part of the exhaust discharged from the cylinder into the cylinder as intake air;
An intake air amount adjusting means for adjusting at least one of the amount of air guided into the cylinder through the intake passage and the amount of exhaust gas guided into the cylinder through the recirculation passage;
Exhaust amount adjusting means for adjusting the amount of exhaust discharged from the cylinder;
And further comprising driving information detecting means for detecting information relating to the driving state of the mechanical device,
The control means controls at least one of the intake air amount adjusting means and the exhaust gas amount adjusting means on the basis of information related to the operating state detected by the operating information detecting means, so that before the self-ignition combustion, Controls the amount of air introduced into the cylinder through the intake passage, the amount of exhaust introduced into the cylinder through the recirculation passage, and the amount of burned gas remaining in the cylinder, and the air-fuel ratio of the air-fuel mixture 6. The engine system according to claim 1, wherein the engine system is set to a stoichiometric air-fuel ratio. The intake air amount adjusting means includes first intake air amount adjusting means for adjusting the flow rate in the intake passage, and second intake air amount adjusting means for adjusting the flow rate in the recirculation passage,
The control means is at least one of the first intake air amount adjusting means, the second intake air amount adjusting means, and the exhaust air amount adjusting means based on information related to the operating state detected by the operating information detecting means. By controlling the amount of air introduced into the cylinder through the intake passage, the amount of exhaust introduced into the cylinder through the recirculation passage, and the burned gas remaining in the cylinder before the self-ignition combustion. The engine system according to claim 6, wherein the amount of the engine is controlled. The intake air amount adjusting means includes third intake air amount adjusting means for adjusting the amount of intake air including air guided into the cylinder through the intake passage and exhaust gas guided into the cylinder through the recirculation passage,
The control means controls at least one of the third intake air amount adjusting means and the exhaust air amount adjusting means on the basis of information related to the operating state detected by the operating information detecting means, so that the pre-ignition combustion And controlling the amount of air introduced into the cylinder through the intake passage, the amount of exhaust introduced into the cylinder through the recirculation passage, and the amount of burned gas remaining in the cylinder. The engine system according to claim 6. The intake air amount adjusting means includes a first intake air amount adjusting means for adjusting a flow rate in the intake passage, a second intake air amount adjusting means for adjusting a flow rate in the recirculation passage, and the cylinder through the intake passage. A third intake air amount adjusting means for adjusting the amount of intake air including air guided to the exhaust and exhaust gas guided into the cylinder through the recirculation passage;
The control means, based on the information on the driving state detected by the driving information detecting means, the first intake air amount adjusting means, the second intake air amount adjusting means, the third intake air amount adjusting means, By controlling at least one of the exhaust amount adjusting means, the amount of air guided into the cylinder through the intake passage, the amount of exhaust guided into the cylinder through the recirculation passage before self-ignition combustion, and The engine system according to claim 6, wherein the amount of burnt gas remaining in the cylinder is controlled. Driving wheels,
An engine system according to any one of claims 1 to 9,
A vehicle comprising: a transmission mechanism that transmits power generated by the engine system to the drive wheels.

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