JP2009127485A - Internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an internal combustion engine capable of properly avoiding knocking in response to an operation state. <P>SOLUTION: This internal combustion engine includes: an intake passage 62 comprising an intake port 19 communicating with a combustion chamber 18 and freely opened-closed by an intake valve 21 and provided with a throttle valve 39; an intake flow control means 63 arranged in the intake passage 62 downstream of the throttle valve 39 in the intake direction and capable of opening-closing the intake passage 62; a cylinder inside gas temperature detecting means capable of detecting the cylinder inside gas temperature being the gas temperature in the combustion chamber 18, a rotating seed detecting means 57 capable of detecting an engine speed of the internal combustion engine; a load detecting means 55 capable of detecting a load of the internal combustion engine; and a control means 51 controlling opening of the intake flow control means 63 based on the internal combustion engine load and the cylinder inside gas temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an internal combustion engine, and more particularly to an internal combustion engine having an intake flow control valve in an intake passage.

  Some conventional internal combustion engines include an intake device having an intake flow control valve mounted in an intake pipe, and the air flow introduced into the combustion chamber is controlled by opening and closing the intake flow control valve. As such a conventional internal combustion engine, for example, an internal combustion engine described in Patent Document 1 is configured to warm up the engine by opening the intake flow control valve halfway when the engine output torque is higher than the reference output torque. The output of unnecessary output torque during operation is suppressed.

JP 11-287134 A

  By the way, in an internal combustion engine equipped with such an intake flow control valve, for example, the ignition timing is set to an optimal ignition timing corresponding to the opening of the intake flow control valve. At this time, when switching the opening of the intake flow control valve, the ignition timing is changed stepwise or with a limit on the range of change, and when the ignition timing is changed to the advance side, knock occurrence data is changed. Feedback is made and the ignition timing is changed under the condition that knock does not occur. That is, for example, in the knock generation region, the ignition timing is gradually retarded or advanced in accordance with the learning value (update width) by the knock control system (KCS) to advance to the optimum value, the so-called limit at which knocking occurs. The occurrence of knocking is suppressed by converging to the Trace Knock ignition timing, which is the ignition timing in the state (knock limit) made to occur. However, in this case, for example, the ignition timing at which the torque that can be extracted from the internal combustion engine is maximum in order to obtain a high shaft torque, that is, the so-called MBT ignition timing (minimum advance for best torque) is the ignition timing. The more the angle is retarded, the lower the shaft torque and the lower the engine efficiency. That is, in order to avoid knocking, there is a possibility that engine efficiency is lowered and fuel consumption is deteriorated.

  Therefore, an object of the present invention is to provide an internal combustion engine that can appropriately avoid knocking according to the operating state.

  In order to achieve the above object, an internal combustion engine according to a first aspect of the present invention includes an intake port that is connected to a combustion chamber and that can be opened and closed by an intake valve and that is provided with a throttle valve, and an intake direction. An intake flow control means provided in the intake passage downstream of the throttle valve and capable of opening and closing the intake passage, and an in-cylinder gas temperature detecting means capable of detecting an in-cylinder gas temperature that is a gas temperature in the combustion chamber A rotation speed detection means capable of detecting an internal combustion engine rotation speed; a load detection means capable of detecting an internal combustion engine load; and the intake air based on the internal combustion engine rotation speed, the internal combustion engine load, and the in-cylinder gas temperature. And a control means for controlling the opening degree of the flow control means.

  In the internal combustion engine according to a second aspect of the present invention, the control means controls the intake air flow so that the in-cylinder gas temperature decreases in an operating state in which knocking may occur when operating at an optimal ignition timing at which the maximum torque that can be taken out. The opening degree of the control means is controlled.

  In the internal combustion engine according to a third aspect of the invention, the control means controls the opening degree of the intake flow control means so that the in-cylinder gas temperature is lowered in a transient operation state in which knocking is likely to occur. And

  In an internal combustion engine according to a fourth aspect of the present invention, the control means opens the intake flow control means so that the in-cylinder gas temperature rises in an operating state where warm-up is not completed and knocking is unlikely to occur. It is characterized by controlling the degree.

  According to the internal combustion engine of the present invention, the opening of the intake air flow control means is controlled by the control means based on the in-cylinder gas temperature, the internal combustion engine rotational speed, and the internal combustion engine load. Can be avoided.

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

  1 is a schematic configuration diagram showing an engine according to an embodiment of the present invention, FIG. 2 is a partial cross-sectional view including a combustion chamber of the engine according to the embodiment of the present invention, and FIG. 3 is according to the embodiment of the present invention. FIG. 4 is a diagram showing an example of the relationship between the TCV opening of the engine and the in-cylinder gas temperature, and FIG. 4 is a diagram showing an example of the relationship between the TCV opening of the engine and the engine efficiency according to the embodiment of the present invention. FIG. 5 is a flowchart for explaining TCV opening control of the engine according to the embodiment of the present invention. FIG. 6 is a main part including a TCV opening calculation unit and a torque calculation unit of the ECU included in the engine according to the embodiment of the present invention. FIG. 7 is a schematic diagram showing an example of the configuration, and FIG. 7 is a schematic diagram showing an example of a map of the engine speed, air amount (load), IVC timing in-cylinder gas temperature and TCV opening degree of the engine according to the embodiment of the present invention. 8 and 8 are related to the embodiment of the present invention. FIG. 9 is a flowchart for explaining the TCV opening control of the engine according to the modified example 1 of the present invention, and FIG. FIG. 11 is a schematic diagram illustrating an example of a TCV opening map of a conventional engine. FIG. 11 is a flowchart for explaining engine TCV opening control according to a second modification of the invention.

  As shown in FIGS. 1 and 2, an engine 10 as an internal combustion engine according to the present embodiment is mounted on a vehicle such as a passenger car or a truck, and a piston 14 provided in a cylinder bore 13 so as to be capable of reciprocating is reciprocated twice. In addition, the engine is a so-called four-cycle engine that performs a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke.

  The engine 10 is of a multi-cylinder type, and a cylinder head 12 is fastened on a cylinder block 11. Pistons 14 are respectively fitted to a plurality of cylinder bores 13 formed on the cylinder block 11 so as to be vertically movable. ing. A crankcase 15 is fastened to the lower part of the cylinder block 11, and a crankshaft 16 is rotatably supported in the crankcase 15. Each piston 14 is connected to the crankshaft 16 via a connecting rod 17. Has been. Note that oil supplied to each part of the engine 10 is stored at the bottom of the crankcase 15.

  The combustion chamber 18 is constituted by the wall surface of the cylinder bore 13 in the cylinder block 11, the lower surface of the cylinder head 12, and the top surface of the piston 14, and the combustion chamber 18 has an upper portion, that is, a central portion of the lower surface of the cylinder head 12. It has a pent roof shape that is inclined so as to be higher. In the combustion chamber 18, a mixture of fuel and air can be combusted, and an intake port 19 and an exhaust port 20 are formed on the upper portion of the combustion chamber 18 so as to face each other. On the other hand, the lower ends of the intake valve 21 and the exhaust valve 22 are positioned. The intake valve 21 and the exhaust valve 22 are supported by the cylinder head 12 so as to be movable in the axial direction, and are urged and supported in a direction (upward in FIG. 1) for closing the intake port 19 and the exhaust port 20. ing. An intake camshaft 23 and an exhaust camshaft 24 are rotatably supported on the cylinder head 12, and the intake cam 25 and the exhaust cam 26 are in contact with upper ends of the intake valve 21 and the exhaust valve 22.

  Although not shown, an endless timing chain is wound around the crankshaft sprocket fixed to the crankshaft 16 and the camshaft shaft sprockets fixed to the intake camshaft 23 and the exhaust camshaft 24, respectively. The crankshaft 16, the intake camshaft 23, and the exhaust camshaft 24 can be interlocked.

  Accordingly, when the intake camshaft 23 and the exhaust camshaft 24 rotate in synchronization with the crankshaft 16, the intake cam 25 and the exhaust cam 26 move up and down the intake valve 21 and the exhaust valve 22 at a predetermined timing. 19 and the exhaust port 20 can be opened and closed so that the intake port 19 and the combustion chamber 18 can communicate with the combustion chamber 18 and the exhaust port 20, respectively. In this case, the intake camshaft 23 and the exhaust camshaft 24 are set to rotate once (360 degrees) while the crankshaft 16 rotates twice (720 degrees). Therefore, the engine 10 executes the four strokes of the intake stroke, the compression stroke, the expansion stroke, and the exhaust stroke while the crankshaft 16 rotates twice. At this time, the intake camshaft 23 and the exhaust camshaft 24 are set to one. It will rotate.

  Further, the valve mechanism of the engine 10 is a variable valve timing-intelligent (VVT) mechanism 27 or 28 that controls the intake valve 21 and the exhaust valve 22 at an optimal opening / closing timing according to the operating state. It has become. The intake / exhaust variable valve mechanisms 27, 28 as variable valve means are configured by providing VVT controllers 29, 30 at the shaft ends of the intake camshaft 23 and the exhaust camshaft 24. 32, the phase of the camshafts 23 and 24 with respect to the cam sprocket is changed by causing the hydraulic pressure from 32 to act on the advance chamber and retard chamber (not shown) of the VVT controllers 29 and 30, and the opening / closing timing of the intake valve 21 and the exhaust valve 22 is changed. Can be advanced or retarded. In this case, the intake / exhaust variable valve operating mechanisms 27, 28 advance or retard the opening / closing timing while keeping the operating angle (opening period) of the intake valve 21 and the exhaust valve 22 constant. Further, the intake camshaft 23 and the exhaust camshaft 24 are provided with cam position sensors 33 and 34 for detecting their rotational phases.

  A surge tank 36 is connected to the intake port 19 via an intake manifold 35, and an intake pipe 37 is connected to the surge tank 36. An air cleaner 38 is attached to an air intake port of the intake pipe 37. . An electronic throttle device 40 as a load adjusting means having a throttle valve 39 is provided downstream of the air cleaner 38 in the air flow direction. Further, the cylinder head 12 is provided with an injector (fuel injection valve) 41 as fuel injection means capable of injecting fuel into the intake port 19 (see FIG. 2). The injector 41 is provided such that the fuel injection port opens into the intake port 19. An injector 41 attached to each cylinder is connected to a delivery pipe 42, and a high-pressure fuel pump (fuel pump) 44 is connected to the delivery pipe 42 via a high-pressure fuel supply pipe 43. Further, a spark plug 45 is mounted on the cylinder head 12 as ignition means for igniting the air-fuel mixture located above the combustion chamber 18.

  Further, the engine 10 serves as an intake flow control means in the intake passage 62, and controls an intake flow flowing through the intake passage 62 to generate a swirl flow such as a swirl flow or a tumble flow. (Hereinafter abbreviated as “TCV”) 63 is provided. The intake passage 62 includes an intake pipe 37, an intake manifold 35, an intake port 19, and the like, and is a passage through which air supplied to the combustion chamber 18 flows. The TCV 63 is provided in the intake passage 62 downstream of the throttle valve 39 and upstream of the injector 41 with respect to the air flow direction, that is, the intake direction.

  The TCV 63 can open and close the intake passage 62 by a valve body, and changes the passage cross-sectional area through which the intake passage 62 can be opened and air can pass, that is, the tumble flow to the combustion chamber 18 by changing the opening degree. Controls the strength of the vortex. The TCV 63 is connected to an ECU 51 described later, and the ECU 51 controls the driving of the TCV 63, that is, the opening degree of the TCV 63, according to the operating state of the engine 10. In the present embodiment, the intake flow control means of the present invention is described as being the TCV 63. However, for example, a swirl control valve (SCV) that generates a swirl flow such as a swirl flow in the air supplied to the combustion chamber 18 is used. It may be.

  On the other hand, an exhaust pipe 47 is connected to the exhaust port 20 via an exhaust manifold 46. The exhaust pipe 47 is a three-way element that purifies harmful substances such as HC, CO, and NOx contained in the exhaust gas. Catalysts 48 and 49 are mounted. Further, the engine 10 is provided with a starter motor 50 that performs cranking. When an unillustrated pinion gear meshes with the ring gear when the engine is started, the rotational force is transmitted from the pinion gear to the ring gear to rotate the crankshaft 16. Can do.

  By the way, the vehicle is equipped with an electronic control unit (ECU) 51 as a control means that is configured around a microcomputer and can control each part of the engine 10, and this ECU 51 includes an injector 41, a spark plug 45, a TCV 63, and the like. Can be controlled. An air flow sensor 52 and an intake air temperature sensor 53 are mounted on the upstream side of the air flow direction of the intake pipe 37, and an intake pressure sensor 54 is provided in the surge tank 36, and the measured intake air amount, intake air temperature, The atmospheric pressure (intake pipe negative pressure) is output to the ECU 51. The electronic throttle device 40 is equipped with a throttle position sensor 55 as load detecting means, and outputs the current throttle opening to the ECU 51. Here, the ECU 51 can calculate the engine load (load factor) as the internal combustion engine load based on the detected throttle opening and intake air amount. The accelerator position sensor 56 outputs the current accelerator opening to the ECU 51. Further, a crank angle sensor 57 as a rotational speed detecting means for detecting the crank angle of the engine 10 outputs the detected crank angle of each cylinder to the ECU 51, and the ECU 51 performs an intake stroke in each cylinder based on the detected crank angle. In addition to determining the compression stroke, the expansion stroke, and the exhaust stroke, the engine speed as the internal combustion engine speed is calculated. Here, the engine speed corresponds to the rotational speed of the crankshaft 16 in other words. If the rotational speed of the crankshaft 16 increases, the rotational speed of the crankshaft 16, that is, the engine rotational speed of the engine 10 also increases. Get higher.

  The cylinder block 11 is provided with a water temperature sensor 58 that detects the engine cooling water temperature, and outputs the detected engine cooling water temperature to the ECU 51. The delivery pipe 42 communicating with each injector 41 is provided with a fuel pressure sensor 59 that detects the fuel pressure, and outputs the detected fuel pressure to the ECU 51. On the other hand, the exhaust pipe 47 is provided with an A / F sensor 60 that detects the air-fuel ratio of the engine 10 upstream of the three-way catalyst 48 in the exhaust gas flow direction, and an oxygen sensor 61 downstream of the exhaust gas flow direction. The A / F sensor 60 detects the exhaust gas air-fuel ratio of the exhaust gas before being introduced into the three-way catalyst 48, outputs the detected air-fuel ratio to the ECU 51, and the oxygen sensor 61 is discharged from the three-way catalyst 48. Thereafter, the oxygen concentration of the exhaust gas is detected, and the detected oxygen concentration is output to the ECU 51. The air-fuel ratio (estimated air-fuel ratio) detected by the A / F sensor 60 is used for feedback control of the air-fuel ratio (theoretical air-fuel ratio) of the mixed gas composed of intake air and fuel. That is, the A / F sensor 60 detects the exhaust air-fuel ratio from the rich range to the lean range from the oxygen concentration in the exhaust gas and the unburned gas concentration, and feeds this back to the ECU 51 to correct the fuel injection amount. Thus, the combustion can be controlled to an optimum combustion state that matches the operating state.

  Therefore, the ECU 51 drives the high-pressure fuel pump 44 based on the detected fuel pressure so that the fuel pressure becomes a predetermined pressure, and also detects the detected intake air amount, intake air temperature, intake pressure, throttle opening, accelerator opening. The fuel injection amount (fuel injection period), the injection timing, the ignition timing, etc. are determined based on the engine operating state such as the engine speed and the engine cooling water temperature, and the injector 41 and the spark plug 45 are driven to perform the fuel injection and ignition. Execute. Further, the ECU 51 feeds back the detected oxygen concentration of the exhaust gas to correct the fuel injection amount so that the air-fuel ratio becomes stoichiometric (theoretical air-fuel ratio).

  The ECU 51 can control the intake / exhaust variable valve mechanisms 27 and 28 based on the engine operating state. That is, when the temperature is low, the engine is started, the engine is idle, or the load is light, the exhaust gas blows back into the intake port 19 or the combustion chamber 18 by eliminating the overlap between the exhaust valve 22 closing timing and the intake valve 21 opening timing. Reduce the amount to enable stable combustion and improved fuel efficiency. Further, at the time of medium load, by increasing the overlap, the internal EGR rate is increased to improve the exhaust gas purification efficiency, and the pumping loss is reduced to improve the fuel consumption. Further, at the time of high-load low-medium rotation, the closing timing of the intake valve 21 is advanced, thereby reducing the amount of intake air that blows back to the intake port 19 and improving the volume efficiency. At the time of high load and high rotation, the closing timing of the intake valve 21 is retarded in accordance with the rotation speed, so that the timing is adjusted to the inertial force of the intake air and the volume efficiency is improved.

  In the engine 10 configured as described above, the fuel injected from the injector 41 and the air sucked through the intake port 19 are mixed to form an air-fuel mixture, and the piston 14 descends in the cylinder bore 13. Thus, this air-fuel mixture is sucked into the combustion chamber 18 (intake stroke). Then, the air-fuel mixture is compressed by the piston 14 going up in the cylinder bore 13 through the intake stroke bottom dead center (compression stroke), and when the piston 14 approaches the vicinity of the compression stroke top dead center, the mixture is made into the air-fuel mixture by the spark plug 45. It is ignited, the air-fuel mixture burns, and the piston 14 is lowered by the combustion pressure (expansion stroke). The air-fuel mixture after combustion is discharged as exhaust gas through the exhaust port 20 when the piston 14 rises again toward the top dead center of the intake stroke via the expansion stroke bottom dead center (exhaust stroke). The reciprocating motion of the piston 14 in the cylinder bore 13 is transmitted to the crankshaft 16 through the connecting rod 17, where it is converted into a rotational motion and taken out as an output. When 16 further rotates due to inertial force, the cylinder bore 13 reciprocates as the crankshaft 16 rotates. By rotating the crankshaft 16 twice, the piston 14 reciprocates the cylinder bore 13 twice, during which a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke is performed, and once in the combustion chamber 18. Explosion takes place.

  At this time, the ECU 51 controls the opening of the TCV 63 and opens and closes the intake passage 62 to generate a vortex flow such as a tumble flow in the air supplied to the combustion chamber 18, thereby improving the combustion efficiency of the fuel. Can do.

  By the way, in the engine 10, for example, in a knock generation region where knocking occurs, the ignition timing is gradually retarded or advanced according to the learning value (update width) by the knock control system (KCS), so-called optimum value. If the occurrence of knocking is suppressed by converging to the Trace Knock ignition timing, which is the ignition timing in a state advanced to the limit at which knocking occurs (knock limit), the engine efficiency may be reduced. Here, the trace knock ignition timing is a limit ignition timing at which knocking occurs, and knocking occurs when ignited on the advance side of the trace knock ignition timing, while knocking occurs when ignited on the retard side. Does not occur. That is, for example, the ignition timing is delayed with respect to the ignition timing at which the torque that can be extracted from the engine 10 is maximized in order to obtain high shaft torque, that is, the so-called MBT ignition timing (minimum advance for best torque). The more the angle is set, the lower the shaft torque and the lower the engine efficiency. As a result, in order to avoid knocking, the engine efficiency may decrease and the fuel efficiency may deteriorate.

  Therefore, in the engine 10 of the present embodiment, the ECU 51 controls the opening degree of the TCV 63 based on the in-cylinder gas temperature at the closing timing of the intake valve 21, the engine speed, and the engine load, so that the engine 10 according to the operating state. Properly avoiding knocking.

  Here, the in-cylinder gas temperature at the closing timing of the intake valve 21 is the in-cylinder gas temperature at the timing when the intake valve 21 is closed, that is, a so-called intake valve closed (hereinafter abbreviated as “IVC”) timing. That is, the combustion chamber 18, in other words, the inside of the cylinder becomes a closed system from other systems after the IVC period. And if the in-cylinder gas temperature at the IVC timing when the cylinder is closed from another system is greater than or equal to the predetermined temperature, the crank angle has advanced and the unburned gas temperature in the cylinder has increased. At this time, the temperature reaches the temperature at which the unburned fuel in the cylinder self-ignites, and at this time, if the amount of unburned fuel in the combustion chamber 18 remains large enough to cause knocking, knocking occurs. In other words, if the IVC timing in-cylinder gas temperature is sufficiently low, even if the crank angle advances and the unburned gas temperature in the cylinder increases, the temperature at which the unburned fuel self-ignites does not reach and knocking does not occur. Furthermore, knocking can be avoided by appropriately controlling the IVC timing cylinder interior gas temperature.

  The IVC timing cylinder interior gas temperature is equal to the TCV opening degree of the TCV 63 that controls the intake flow flowing through the intake passage 62 as shown in a diagram showing an example of the relationship between the TCV opening degree and the cylinder interior gas temperature in FIG. It can be controlled by adjusting the degree. In other words, the engine 10 can reduce the IVC timing in-cylinder gas temperature and suppress knocking by adjusting the opening of the TCV 63 even with the same amount of intake air. That is, the engine 10 including the TCV 63 of the present embodiment can adjust the in-cylinder gas temperature according to the opening of the TCV 63 by adjusting the opening of the TCV 63, and this in-cylinder gas according to the operating state. By adjusting the temperature, as shown in FIGS. 3 and 4, the knock characteristic (ease of occurrence of knocking) can be changed. Therefore, the knock characteristic can be controlled by controlling the opening of the TCV 63. .

  For this reason, the engine 10 of the present embodiment controls the opening of the TCV 63 based on the IVC timing cylinder interior gas temperature, the engine speed, and the engine load by the ECU 51, for example, the MBT that maximizes the torque that can be extracted. By controlling the opening of the TCV 63 so that the IVC timing in-cylinder gas temperature decreases in an operating state in which knocking may occur when operating at the ignition timing (optimum ignition timing), the IVC timing in-cylinder gas temperature is reduced. It is possible to reduce knocking and avoid the knocking, and to set the ignition timing to the MBT ignition timing without delaying from the MBT ignition timing. In other words, the engine 10 can reduce the IVC timing in-cylinder gas temperature and avoid knocking by controlling the opening of the TCV 63. The engine 10 can reduce the IVC timing in-cylinder gas temperature by controlling the opening degree of the TCV 63 to avoid knocking, so that a line representing an example of the relationship between the TCV opening degree and the engine efficiency in FIG. As shown in the figure, the knock occurrence region, in other words, the trace knock ignition timing, which is the ignition timing at the knock limit, can be moved to the advance side (efficient ignition timing side), and the ignition timing can be changed to the MBT ignition timing. It is possible to increase the operating range that can be set to, thus improving the engine efficiency. That is, the engine 10 can avoid knocking and suppress deterioration in engine efficiency and suppress deterioration in fuel consumption. As a result, knocking can be appropriately avoided according to the driving state.

  Next, TCV opening control of the engine 10 according to the present embodiment will be described with reference to the flowchart of FIG.

  First, the ECU 51 receives the intake air amount, intake air temperature, intake pressure, throttle opening, accelerator opening, engine speed, valve timing, valve lift amount, engine cooling water temperature, oil temperature, air fuel ratio, fuel injection from the various sensors. Various parameters relating to the current operating conditions of the engine 10 such as the amount (fuel injection period), injection timing, and ignition timing are acquired (S100). Next, the ECU 51 determines the required torque Td (driver required torque + auxiliary load required torque + friction +) to be output to the drive shaft based on the accelerator opening degree, the vehicle speed, etc. corresponding to the depression amount of the accelerator pedal by the driver. .) Is calculated (S102), and the target torque Tp is set based on the required torque Td (S104). For example, the ECU 51 calculates a torque that can be generated under the current operating conditions, and sets a realizable target torque Tp. The ECU 51 sets the maximum torque that can be generated as the target torque Tp when the torque that can be generated is lower than the required torque Td.

  Next, the ECU 51 sets target operation values (throttle opening, fuel injection amount (fuel injection period), injection timing, ignition timing, air-fuel ratio, intake valve 21 and exhaust valve for each part of the engine 10 for realizing the target torque Tp. 22 is calculated, and the normal engine efficiency ηt, which is the engine efficiency when the ignition timing is retarded as usual by KCS under these operating conditions, is calculated (S106). For example, the ECU 51 predicts the intake air amount from the throttle opening, etc., and calculates the shaft torque by estimating the fuel injection amount, A / F, etc. of the injector 41 based on the intake air amount and ignition timing, The normal engine efficiency ηt is calculated by dividing the shaft torque by the fuel injection amount.

  Next, the ECU 51 sets the limit trace knock ignition timing Stk [deg.] At which knocking occurs under the target operating condition corresponding to the target operation value calculated in S106. BTDC] is the MBT ignition timing Smbt [deg. It is determined whether or not the angle is delayed from BTDC] (S108). In the target operating condition, when the trace knock ignition timing Stk is not retarded from the MBT ignition timing Smbt (S108: No), that is, when the MBT ignition timing Smbt is outside the knocking occurrence region, the ignition timing is set to the MBT ignition as usual. Since the timing Smbt can be set, the ECU 51 shifts to the next control cycle.

  When the trace knock ignition timing Stk is retarded from the MBT ignition timing Smbt under the target operating conditions (S108: Yes), that is, when the MBT ignition timing Smbt is within the knocking occurrence region under the target operating conditions. Since the ignition timing is set to be retarded from the MBT ignition timing Smbt, there is a possibility that the engine efficiency may be lowered. Therefore, the ECU 51 reduces the IVC timing in-cylinder gas temperature in order to avoid knocking. A knock avoidance maximum torque Tk that is the maximum torque when the opening degree of the TCV 63 is controlled is calculated, and a knock avoidance engine efficiency ηk that is an engine efficiency at this time is calculated (S110).

  FIG. 6 is a schematic configuration diagram illustrating an example of a main configuration including a TCV opening calculation unit and a torque calculation unit of the ECU 51. Specifically, the ECU 51 is configured to calculate the knock avoidance maximum torque Tk, and here, an in-cylinder gas temperature calculation unit 71 as an in-cylinder gas temperature detection unit, and an air amount (load) calculation unit 72. And a TCV opening calculation unit 73 and a torque calculation unit 74.

  The in-cylinder gas temperature calculation unit 71 can detect the in-cylinder gas temperature that is the gas temperature in the combustion chamber 18. Here, the in-cylinder gas temperature calculation unit 71 stores an in-cylinder gas temperature map created in advance by experiments or the like according to the operating conditions, and includes the target torque Tp and the engine speed NE calculated in S104. Various target operating conditions are input, and the IVC timing in-cylinder gas temperature Tivc is calculated and output based on the in-cylinder gas temperature map. The IVC timing in-cylinder gas temperature Tivc, which is the output of the in-cylinder gas temperature calculation unit 71, is input to the air amount calculation unit 72 and the TCV opening degree calculation unit 73. Here, the in-cylinder gas temperature detection means will be described as being an in-cylinder gas temperature calculation unit 71 that calculates the in-cylinder gas temperature based on an in-cylinder gas temperature map created in advance through experiments or the like. For example, a sensor that can directly detect or indirectly estimate the in-cylinder gas temperature may be used.

  The air amount calculation unit 72 can calculate the amount of air taken into the combustion chamber 18 as a value corresponding to the engine load. Here, the air amount calculation unit 72 stores an air amount calculation map created in advance by experiments or the like according to operating conditions, and the target torque Tp, engine speed NE, cylinder gas temperature calculated in S104 are stored. Various target operating conditions such as the IVC timing in-cylinder gas temperature Tivc calculated by the calculation unit 71 are input, and the target air amount KLt is calculated and output based on the air amount calculation map. The target air amount KLt, which is the output of the air amount calculation unit 72, is input to the TCV opening degree calculation unit 73.

  The TCV opening calculation unit 73 can calculate the TCV opening of the TCV 63. Here, the TCV opening calculation unit 73 stores a TCV opening map created in advance by experiments or the like according to the operating conditions, and the IVC calculated by the engine speed NE and the in-cylinder gas temperature calculation unit 71. Various target operating conditions such as the timing in-cylinder gas temperature Tivc and the target air amount KLt calculated by the air amount calculation unit 72 are input, and the TCV opening instruction value A is calculated and output based on the TCV opening map. Here, the TCV opening calculation unit 73 also calculates the maximum air amount (load) KLmax, which is the maximum air amount (load) that can achieve the required IVC timing in-cylinder gas temperature Tivc, based on a map or the like. And output. The TCV opening instruction value A and the maximum air amount (load) KLmax, which are outputs of the TCV opening calculation unit 73, are input to the torque calculation unit 74.

  Here, FIG. 7 is a schematic diagram illustrating an example of a map of the engine speed, the air amount (load), the IVC timing cylinder interior gas temperature, and the TCV opening degree of the engine 10 according to the present embodiment. On the other hand, FIG. 11 is a schematic diagram showing an example of a TCV opening map of a conventional engine. Here, the TCV opening degree of the conventional engine shown in FIG. 11 is determined based on the air amount (load) KL and the engine speed NE, and is set to be closed as much as possible within a range where the volumetric efficiency is not lowered. Therefore, the TCV opening cannot be controlled according to the in-cylinder gas temperature, and the in-cylinder gas temperature cannot be controlled according to the TCV opening, that is, the IVC timing in-cylinder gas can be appropriately controlled by controlling the TCV opening. The temperature could not be lowered. On the other hand, the TCV opening of the engine 10 of this embodiment is determined based on the engine speed NE, the air amount (load) KL, and the IVC timing in-cylinder gas temperature Tivc, as shown in FIG. The TCV opening can be controlled according to the gas temperature and the in-cylinder gas temperature can be controlled according to the TCV opening, that is, the IVC timing in-cylinder gas temperature can be appropriately reduced by controlling the TCV opening. it can. The TCV opening degree calculation unit 73 uses the three-dimensional TCV opening degree map based on the engine speed NE, the air amount (load) KL, and the IVC timing in-cylinder gas temperature Tivc as shown in FIG. The value A is calculated and output.

  The lower part of FIG. 7 illustrates a TCV opening degree map when the IVC timing cylinder interior gas temperature Tivc is 400K. The TCV 63 tends to have a stronger tumble flow and a lower in-cylinder gas temperature and become difficult to knock as the opening is reduced and the throttle is increased. On the other hand, if the opening is too small, the intake flow in the TCV 63 is reduced. Increasing pressure loss tends to increase the in-cylinder gas temperature and facilitate knocking. Therefore, the TCV opening degree map based on the engine speed NE, the air amount (load) KL, and the IVC timing in-cylinder gas temperature Tivc of the present embodiment is prepared in advance by experiments or the like according to the operating conditions. It is good to create it based on the tendency.

  Further, the TCV opening calculation unit 73 further uses the TCV opening instruction value A calculated by using the TCV opening map to further retard or advance the opening / closing timing of the intake valve 21 and the exhaust valve 22 by the VVTs 27 and 28 ( You may correct | amend using a correction formula according to various target operation conditions, such as in / exVVT) and valve lift amount (VL). In this case, a more appropriate TCV opening instruction value A can be calculated.

  Returning to FIG. 6, the torque calculator 74 can calculate the torque of the engine 10. Here, the torque calculation unit 74 stores a torque map created in advance by experiments or the like according to operating conditions, and the TCV opening degree instruction value A calculated by the TCV opening degree calculation unit 73 and the maximum air amount ( Load) Various target operating conditions such as KLmax are input, and the above-described knock avoiding maximum torque Tk is calculated and output based on the torque map.

  FIG. 8 is a schematic configuration diagram illustrating an example of a main configuration including the engine efficiency calculation unit 76 of the ECU 51. Specifically, the ECU 51 includes a torque calculation unit 75 and an engine efficiency calculation unit 76 as a configuration for calculating the engine efficiency ηk at the time of knock avoidance.

  The torque calculation unit 75 is capable of calculating the torque of the engine 10 and may also be used as the torque calculation unit 74 described above. Here, the torque calculation unit 75 stores a torque map created in advance by experiments or the like according to operating conditions, and various target operating conditions such as a target air amount KLt and an air-fuel ratio (A / F) are input. Then, the estimated torque Tk ′ is calculated and output based on the torque map. The estimated torque Tk ′ that is the output of the torque calculation unit 75 is input to the engine efficiency calculation unit 76.

  The engine efficiency calculation unit 76 can calculate the engine efficiency of the engine 10. Here, the engine efficiency calculation unit 76 calculates the engine efficiency from, for example, [engine efficiency = estimated torque / fuel consumption] and [fuel consumption = air amount (KL) / air-fuel ratio (A / F)]. Can do. The engine efficiency calculation unit 76 receives various target operating conditions such as the target air amount KLt, the air-fuel ratio (A / F), the estimated torque Tk ′ calculated by the torque calculation unit 75, and calculates the engine efficiency ηk at the time of knock avoidance. Calculate and output.

  Returning to FIG. 5, the ECU 51 determines whether or not the knock avoidance maximum torque Tk calculated in S110 is equal to or greater than the target torque Tp (S112). When it is determined that the maximum torque Tk for avoiding knocking is smaller than the target torque Tp (S112: No), the maximum when the opening degree of the TCV 63 is controlled so as to lower the IVC timing in-cylinder gas temperature to avoid knocking. Since the target torque Tp is not reached even with the maximum knock avoidance torque Tk that is torque, the ECU 51 shifts to the next control cycle without executing the opening degree control of the TCV 63.

  When it is determined that the maximum torque Tk at the time of knock avoidance is equal to or greater than the target torque Tp (S112: Yes), that is, the opening degree of the TCV 63 is controlled so as to lower the IVC timing in-cylinder gas temperature in order to avoid knocking. Even in this case, when the target torque Tp can be reached, the ECU 51 determines whether or not the knock avoidance engine efficiency ηk calculated in S110 is higher than the normal engine efficiency ηt (S114). When knock avoidance engine efficiency ηk is equal to or less than normal engine efficiency ηt (S114: No), knock avoidance when the opening of TCV 63 is controlled so as to lower the IVC timing in-cylinder gas temperature to avoid knocking Since the engine efficiency ηk is lower than the normal engine efficiency ηt that is the engine efficiency when the ignition timing is retarded as usual by KCS, the ECU 51 does not execute the opening degree control of the TCV 63 and shifts to the next control cycle. .

  When it is determined that the engine efficiency ηk at the time of knock avoidance is higher than the normal engine efficiency ηt (S114: Yes), that is, the opening degree of the TCV 63 is controlled so as to reduce the IVC timing in-cylinder gas temperature in order to avoid knocking. In this case, when the engine efficiency can be improved from the normal engine efficiency ηt when the ignition timing is retarded as usual by the KCS, the ECU 51 performs the TCV opening instruction value calculated in S110 as the knock avoidance operation. The opening degree control of the TCV 63 is executed based on A (S116). Therefore, by controlling the opening of the TCV 63 so as to reduce the IVC timing cylinder gas temperature, the ignition timing can be set to the MBT ignition timing Smbt after the IVC timing cylinder gas temperature is decreased. As a result, after realizing the target torque Tp (requested torque Td), it is possible to prevent the engine efficiency from being lowered as compared with the case where the ignition timing is retarded as usual, and to appropriately avoid knocking. it can.

  According to the engine 10 according to the embodiment of the present invention described above, the intake passage 62 that includes the intake port 19 that communicates with the combustion chamber 18 and can be opened and closed by the intake valve 21 and that is provided with the throttle valve 39. The TCV 63 provided in the intake passage 62 downstream of the throttle valve 39 with respect to the intake direction and capable of opening and closing the intake passage 62 and the in-cylinder gas temperature of the ECU 51 capable of detecting the in-cylinder gas temperature as the gas temperature in the combustion chamber 18 Gas temperature calculation unit 71, crank angle sensor 57 capable of detecting the engine speed, throttle position sensor 55 capable of detecting the engine load, and in-cylinder gas at the closing speed of the engine speed, the engine load and the intake valve 21 ECU51 which controls the opening degree of TCV63 based on temperature.

  Therefore, the ECU 51 controls the opening degree of the TCV 63 based on the engine speed, the engine load, and the in-cylinder gas temperature at the closing timing of the intake valve 21, thereby suppressing a decrease in engine efficiency and the like and opening the TCV 63. By adjusting the degree, the in-cylinder gas temperature at the closing timing of the intake valve 21 can be adjusted, so that knocking can be appropriately avoided according to the operating state.

  Further, according to the engine 10 according to the embodiment of the present invention described above, the ECU 51 reduces the in-cylinder gas temperature in an operating state in which knocking may occur if the ECU 51 is operated at the optimal ignition timing at which the torque that can be extracted is maximized. Thus, the opening degree of the TCV 63 may be controlled. In this case, the IVC timing cylinder is controlled by controlling the opening of the TCV 63 so that the IVC timing cylinder interior gas temperature decreases in an operating state where knocking may occur when operating at the MBT ignition timing (optimum ignition timing). The internal gas temperature can be reduced to avoid knocking, and the knock generation region, in other words, the trace knock ignition timing, which is the ignition timing at the knock limit, can be moved to the advance side (efficient ignition timing side). The ignition timing can be set to the MBT ignition timing without being retarded from the MBT ignition timing.

  In addition, the internal combustion engine which concerns on embodiment of this invention mentioned above is not limited to embodiment mentioned above, A various change is possible in the range described in the claim. In the above description, the control means may control the opening degree of the intake air flow control means so that the in-cylinder gas temperature is lowered in an operating state in which knocking may occur when operating at the optimal ignition timing at which the maximum torque that can be extracted is operated. However, the present invention is not limited to this, and knocking such as when the learned value (update width) of the ignition timing by the knock control system (KCS) is greater than or equal to a predetermined value set in advance or when the operating state is a transient operating state, etc. The opening degree of the intake air flow control means may be controlled so that the in-cylinder gas temperature is lowered in an operating state in which the generation of the intake gas is likely to occur. Also in this case, knocking can be appropriately avoided according to the operating state. Examples of the case where the learning value (update range) of the ignition timing by the knock control system (KCS) is greater than or equal to a predetermined value set in advance include, for example, when the intake air temperature and humidity are relatively high, There are cases where the detected value is deviated, or deposits attached to the intake valve 21 and the exhaust valve 22 are increased. For example, when the operation state is a transient operation state, for example, during acceleration (fluctuation in air pulsation due to fluctuations in rotational speed), air-fuel ratio fluctuation, fuel property change (fuel vaporization characteristic fluctuation), in-cylinder temperature fluctuation, etc. There are cases where the knock characteristics change due to the above.

  That is, for example, the ECU 51 as the control unit may control the opening of the TCV 63 as the intake air flow control unit so that the in-cylinder gas temperature decreases in a transient operation state in which knocking is likely to occur.

  In this case, the ECU 51 of the engine 10, first, for example, as shown in the flowchart explaining the TCV opening control of the engine 10 according to Modification 1 of the present invention in FIG. (S200), and the current operation state is changed to a transient operation state (acceleration (air pulsation fluctuation due to fluctuations in rotational speed), air-fuel ratio fluctuation, fuel property change (fuel vaporization) by various known determination methods. It is determined whether or not the knock characteristics change due to fluctuations in characteristics) and in-cylinder temperature fluctuations (S202). When it is determined that the current operation state is not the transient operation state (S202: No), the ECU 51 proceeds to the next control cycle.

  When it is determined that the current operation state is the transient operation state (S202: Yes), the ECU 51 calculates the required torque Td (S204), and sets the target torque Tp based on the required torque Td (S206). . Then, three-dimensional based on the engine speed NE, the air amount (load) KL and the in-cylinder gas temperature T according to various target operating conditions such as the target torque Tp, the engine speed NE, and the air amount (load) KL. The TCV opening instruction value A is calculated using the TCV opening map, and the knock avoidance maximum torque Tk2 is calculated (S208).

  Then, it is determined whether the knock avoidance maximum torque Tk2 is equal to or greater than the target torque Tp (S210). If it is determined that the knock avoidance maximum torque Tk2 is smaller than the target torque Tp (S210: No), The ECU 51 shifts to the next control cycle without executing the opening degree control. When it is determined that the knock avoidance maximum torque Tk2 is equal to or greater than the target torque Tp (S210: Yes), the ECU 51 performs TCV63 based on the TCV opening instruction value A calculated in S208 as a transient knock avoidance operation. The opening degree control is executed (S212). Therefore, by controlling the opening of the TCV 63 so as to lower the in-cylinder gas temperature and lowering the IVC timing in-cylinder gas temperature, the target torque Tp (required torque Td) is realized, and at the time of acceleration (rotational speed fluctuation) The TCV opening is controlled following the fluctuations in knock characteristics during transient operation such as fluctuations in air pulsation), air-fuel ratio fluctuations, fuel property changes (fuel vaporization characteristics fluctuations), and in-cylinder temperature fluctuations. And knocking at the time of transition can be avoided appropriately. Further, it is possible to increase the operating range in which the ignition timing can be set to the MBT ignition timing. If priority is given to avoiding knocking, knocking can always be avoided by setting the maximum torque Tk2 for avoiding knocking to the target torque Tp in S210.

  In the above description, the control means has been described as controlling the opening of the intake flow control means so that the in-cylinder gas temperature decreases in an operation state in which knocking is likely to occur. Even in the case of an amount, warming up of the internal combustion engine can be promoted while avoiding knocking by utilizing the fact that the in-cylinder gas temperature can be adjusted by adjusting the opening of the intake air flow control means.

  That is, the ECU 51 as the control means controls the opening of the TCV 63 as the intake air flow control means so that the in-cylinder gas temperature rises, for example, in an operating state in which warm-up is incomplete and knocking is unlikely to occur. You may do it.

  In this case, the ECU 51 of the engine 10 starts with various parameters relating to the current operating conditions of the engine 10, as shown in the flowchart for explaining the TCV opening control of the engine 10 according to the second modification of the present invention in FIG. (S300), for example, by determining whether or not the engine coolant temperature is equal to or lower than a predetermined temperature set in advance, it is determined whether or not the warm-up is incomplete at the current time (S302). When it is determined that the warm-up is completed at the current time (S302: No), the ECU 51 proceeds to the next control cycle.

  When it is determined that the warm-up is not completed at the current time (S302: Yes), the ECU 51 calculates the required torque Td (S304), and sets the target torque Tp based on the required torque Td (S306). . Then, three-dimensional based on the engine speed NE, the air amount (load) KL and the in-cylinder gas temperature T according to various target operating conditions such as the target torque Tp, the engine speed NE, and the air amount (load) KL. The warm-up operation which is the maximum torque when the TCV opening degree instruction value A is calculated using the TCV opening degree map and the opening degree of the TCV 63 is controlled so as to increase the in-cylinder gas temperature in order to promote warm-up. Hour maximum torque Tw is calculated (S308).

  Then, it is determined whether or not the maximum torque Tw during warm-up operation is equal to or greater than the target torque Tp (S310), and when it is determined that the maximum torque Tw during warm-up operation is smaller than the target torque Tp (S310: No), The ECU 51 shifts to the next control cycle without performing the opening degree control of the TCV 63. When it is determined that the maximum torque Tw during the warm-up operation is equal to or greater than the target torque Tp (S310: Yes), the ECU 51 performs TCV63 based on the TCV opening instruction value A calculated in S308 as the warm-up promotion operation. The opening degree control is executed (S312). Therefore, in an operation state in which knocking is unlikely to occur, the target torque Tp (required torque Td) is achieved by controlling the opening of the TCV 63 so as to increase the in-cylinder gas temperature and thereby increasing the in-cylinder gas temperature. It is possible to increase the amount of heat transfer to the wall surface of the cylinder bore 13 etc. after avoiding it properly, and to increase the engine coolant temperature and promote the warm-up of the engine 10. As a result, the warm-up property of the catalyst can be improved, the emission property at the time of starting the engine can be improved, the warm-up property of the oil can be improved, and the friction can be reduced.

  As described above, the internal combustion engine according to the present invention is suitable for use in various internal combustion engines having an intake air flow control valve in the intake passage.

It is a schematic structure figure showing an engine concerning an embodiment of the present invention. It is a fragmentary sectional view containing the combustion chamber of the engine which concerns on embodiment of this invention. It is a diagram showing an example of the relationship between the TCV opening degree of the engine which concerns on embodiment of this invention, and in-cylinder gas temperature. It is a diagram showing an example of the relationship between the TCV opening degree of the engine which concerns on embodiment of this invention, and engine efficiency. It is a flowchart explaining the TCV opening degree control of the engine which concerns on embodiment of this invention. It is a schematic block diagram which shows an example of a principal part structure including the TCV opening calculation part of the ECU with which the engine which concerns on embodiment of this invention is equipped, and a torque calculation part. It is the schematic showing an example of the map of the engine speed of the engine which concerns on embodiment of this invention, air quantity (load), IVC time cylinder gas temperature, and TCV opening degree. It is a schematic block diagram which shows an example of a principal part structure including the engine efficiency calculation part of ECU with which the engine which concerns on embodiment of this invention is provided. It is a flowchart explaining the TCV opening degree control of the engine which concerns on the modification 1 of this invention. It is a flowchart explaining the TCV opening degree control of the engine which concerns on the modification 2 of this invention. It is the schematic showing an example of the TCV opening degree map of a conventional engine.

Explanation of symbols

10 Engine (Internal combustion engine)
14 Piston 18 Combustion chamber 19 Intake port 20 Exhaust port 21 Intake valve 22 Exhaust valve 39 Throttle valve 41 Injector 45 Spark plug 51 ECU (control means)
55 Throttle position sensor (load detection means)
57 Crank angle sensor (rotational speed detection means)
62 Intake passage 63 TCV (intake flow control means)
71 In-cylinder gas temperature calculation unit (in-cylinder gas temperature detection means)

Claims (4)

An intake passage that is configured to include an intake port that communicates with the combustion chamber and can be opened and closed by an intake valve, and is provided with a throttle valve;
An intake flow control means provided in the intake passage downstream of the throttle valve with respect to the intake direction and capable of opening and closing the intake passage;
In-cylinder gas temperature detecting means capable of detecting an in-cylinder gas temperature that is a gas temperature in the combustion chamber;
A rotational speed detecting means capable of detecting the rotational speed of the internal combustion engine;
Load detection means capable of detecting the internal combustion engine load;
Control means for controlling the opening degree of the intake air flow control means based on the internal combustion engine rotation speed, the internal combustion engine load, and the in-cylinder gas temperature,
Internal combustion engine. The control means controls the opening degree of the intake air flow control means so that the in-cylinder gas temperature is lowered in an operating state in which knocking may occur when operating at an optimum ignition timing at which the torque that can be taken out is maximized. And
The internal combustion engine according to claim 1. The control means controls the opening degree of the intake air flow control means so that the in-cylinder gas temperature is lowered in a transient operation state in which knocking is likely to occur.
The internal combustion engine according to claim 1 or 2. The control means controls the opening degree of the intake air flow control means so that the in-cylinder gas temperature rises in an operating state where warm-up is incomplete and knocking is unlikely to occur.
The internal combustion engine according to any one of claims 1 to 3.

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