JP5446706B2 - Internal combustion engine control method and internal combustion engine - Google Patents

Description

  The present invention relates to an internal combustion engine control method and an internal combustion engine. More specifically, the present invention has a fluid pressure type variable valve mechanism capable of improving the control accuracy of lift amounts of intake valves, exhaust valves, or both. The present invention relates to an internal combustion engine control method and an internal combustion engine.

  In the conventional diesel engine, the intake and exhaust valves are opened and closed by cam drive when the intake and exhaust valves are operated for intake into the cylinder and exhaust from the cylinder. Since the camshaft rotates in synchronization with the rotation of the engine, the opening and closing timings of the intake and exhaust valves are always constant at the crank angle base.

By the way, in recent years, exhaust gas regulations and fuel efficiency regulations for diesel engines have become stricter year by year, and in order to achieve the regulation values, not only the improvement of exhaust gas from the engine body due to combustion but also the exhaust pipe after exhausting from the engine body It is necessary to purify the exhaust gas using an exhaust aftertreatment device installed in the factory.

  As an exhaust gas improvement technique by combustion, there is a method using premixed diesel combustion in which fuel is injected at an early stage of the compression stroke and a mixing period is obtained until ignition. However, the premixed diesel combustion has a problem that it is difficult to control the ignition timing and to apply in a high load region because the ignition depends on a chemical reaction.

  Further, the purification of exhaust gas by the exhaust aftertreatment device depends on the temperature of the catalyst, and there is a problem that a certain amount of time is required until the catalyst is activated, especially at the time of cold start.

In response to these problems , the intake and exhaust valves can be opened and closed with fluid pressure instead of conventional cams, and the intake and exhaust valves can be opened and closed arbitrarily. Development of a variable valve mechanism is underway. In this fluid pressure type variable valve mechanism, the opening and closing timings and lift amounts of the intake and exhaust valves are arbitrarily set by controlling the timing and period during which high-pressure working fluid flows into the control chamber ( For example, see Patent Documents 1 and 2).

  When such a fluid pressure type variable valve mechanism is used, an effective compression ratio (compression end) is obtained by retarding the valve closing timing of the intake valve during ignition control of premixed diesel fuel or operation on the high load side. The pressure of the exhaust gas after-treatment device can be increased by advancing the valve opening timing of the exhaust valve until the combustion period.

  However, since the intake and exhaust valves are opened and closed only by the fluid pressure in the fluid pressure type variable valve mechanism, the open and closed states of the intake and exhaust valves are easily affected by disturbance. In particular, when the intake and exhaust valves are opened, the valve thrust required to obtain a preset valve lift amount (set valve lift amount) is increased before and after the intake and exhaust valves (intake and exhaust pipes). There is a problem that the intake amount and the intake composition in the cylinder fluctuate as a result of the actual valve lift amount deviating from the required value (target value).

JP 2003-328713 A JP 2007-321737 A

  An object of the present invention is to provide an internal combustion engine control method and an internal combustion engine capable of improving the control accuracy of lift amounts of intake and exhaust valves and both valves in a hydraulic internal combustion engine.

Ｗ：バルブ推力、Ｆｖ：開弁方向へかかる力、Ｌ：設定したリフト量 In order to achieve the above object, the control method for an internal combustion engine according to the present invention supplies the working fluid to the control chamber, thereby providing valves for intake, exhaust or both at any timing independent of the rotation angle of the crankshaft. Measuring a pressure in a cylinder and an intake / exhaust port of the internal combustion engine at a valve opening timing of the intake or exhaust valve, and the measured Calculating a differential pressure between the pressure in the cylinder and the pressure in the intake / exhaust port based on the pressure, and using the differential pressure, the lift amount in the valve opening process of the intake or exhaust valve obtaining the force applied to the valve opening direction, a step of calculating a valve thrust required to obtain a set lift of the valve for the intake or exhaust from the following equation, the calculated Calculating a necessary supply amount of the working fluid using a valve thrust, and supplying the working fluid to the control chamber according to the calculated necessary supply amount of the working fluid; Opening the valve by the set lift amount.

W: Valve thrust, Fv: Force applied in the valve opening direction, L: Set lift amount

  In the control method for an internal combustion engine, the working fluid is supplied into the control chamber by using the calculated required supply amount of the working fluid at the opening timing of the intake or exhaust valve. Determining a period to be determined by a characteristic map.

Ｗ：バルブ推力、Ｆｖ：開弁方向へかかる力、Ｌ：設定したリフト量 In order to achieve the above object, an internal combustion engine of the present invention opens and closes intake and / or exhaust valves at any timing independent of the rotation angle of a crankshaft by supplying a working fluid to a control chamber. In an internal combustion engine provided with a drive device, a first pressure sensor for measuring a pressure in a cylinder of the internal combustion engine, a second pressure sensor for measuring a pressure of an intake / exhaust port of the internal combustion engine, and the intake or exhaust At the opening timing of the valve, a differential pressure between the pressure in the cylinder measured by the first and second pressure sensors and the pressure at the intake and exhaust ports is calculated, and this differential pressure is used for the intake or the exhaust. of obtaining the force applied to the valve opening direction against the lift in the opening process of the valve, the valve thrust required to obtain a set lift of the valve for the intake or exhaust is calculated from the following equation, the calculation of The required supply amount of the working fluid is calculated using the valve thrust, and the working fluid is supplied to the control chamber according to the calculated required supply amount of the working fluid, so that the intake or exhaust valve is supplied. And a control unit that opens the vehicle with the set lift amount.

W: Valve thrust, Fv: Force applied in the valve opening direction, L: Set lift amount

  Further, in the internal combustion engine, the control unit further uses the calculated necessary supply amount of the working fluid at the valve opening timing of the intake or exhaust valve, and supplies the working fluid to the control chamber. The function is provided with a function for determining the period of supply to the image using the characteristic map.

  According to the control method and the internal combustion engine of the present invention, it is possible to improve the control accuracy of the lift amount of the intake valve, the exhaust valve, or both of them in the internal combustion engine having the fluid pressure type variable valve mechanism. . For this reason, it is possible to realize the expansion of the premixed diesel combustion region, the rapid temperature rise of the exhaust aftertreatment device, the improvement of the combustion efficiency, and the like. Therefore, exhaust gas can be reduced and fuel consumption can be improved.

It is principal part sectional drawing of the internal combustion engine of embodiment of this invention. It is a block diagram of an example of the variable valve system of the internal combustion engine of FIG. It is a flowchart which shows the control process of the internal combustion engine of FIG. It is principal part sectional drawing which shows the pressure state of the internal combustion engine of FIG. FIG. 3 is an enlarged cross-sectional view of a main part showing a pressure state of a variable valve mechanism in the variable valve system of FIG. 2.

  Hereinafter, an internal combustion engine according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows a cross-sectional view of a main part of the internal combustion engine of the present embodiment. The internal combustion engine of the present embodiment is configured as an in-line four-cylinder common rail type diesel engine 1 mounted on an automobile such as a truck, for example. In addition, this invention is not limited to a diesel engine, It can also apply to a gasoline engine etc.

  The diesel engine (hereinafter referred to as engine) 1 supplies fuel to air that has been compressed in a cavity (combustion chamber) 4 that is recessed in the top surface of a piston 3 in a cylinder (cylinder) 2 and that has become hot. The piston 3 is driven by the expanded gas generated by the combustion by the self-ignition at this time.

  The cylinder 2 is a cylindrical part that guides the reciprocating motion of the piston 3 and stores fuel gas. A liner (not shown) is formed on the inner peripheral surface of the cylinder 2. In the cylinder 2, a cooling passage 2 a through which a cooling medium for cooling the cylinder flows is formed in a thick portion outside the liner. In addition, a pressure sensor (first pressure sensor) 2 b for measuring the pressure in the cylinder 2 is installed on the inner upper side of the cylinder 2. The pressure sensor 2b is electrically connected to an electronic control unit (control unit: Engine Control Unit: hereinafter referred to as ECU) described later.

  Inside the cylinder 2, the piston 3 is installed in a state in which the piston 3 can reciprocate along the liner on the inner peripheral surface of the cylinder 2. The lower part of the piston 3 is connected to a crankshaft (not shown) via a connecting rod (not shown). The crankshaft converts the reciprocating motion of the piston 3 into a rotational motion.

  In the cylinder head 5 at the upper part of the cylinder 2, an injector 6 for directly injecting fuel into the cavity 4 is located at a position (on the axis C of the cylinder 2 and the piston 3) facing the center of the top surface of the piston 3. is set up.

  An intake port (intake port) 7 and an exhaust port (exhaust port) 8 are provided on the left and right of the injector 6 in the cylinder head 5. The intake port 7 is connected to the intake pipe 9, and the exhaust port 8 is connected to the exhaust pipe 10.

  The intake port 7 is provided with a pressure sensor (second pressure sensor) 11a for measuring the pressure in the intake port 7, and the exhaust port 8 is provided with a pressure sensor (second pressure) for measuring the pressure in the exhaust port 8. A pressure sensor 11b is installed. The pressure sensors 11a and 11b are electrically connected to the ECU.

  An intake valve 14a (14) is installed on the intake port 7 side, and an exhaust valve 14b (14) is installed on the exhaust port 8 side. The intake valve 14 a opens and closes the intake port 7, and the exhaust valve 14 b opens and closes the exhaust port 8. In the following description, the intake valve 14a and the exhaust valve 14b may be integrated and referred to as an intake / exhaust valve 14 in some cases.

  When the intake / exhaust valve 14 (14a, 14b) is moved downward in FIG. 1, the valve is opened, and when it is moved upward in FIG. 1, the valve is closed. These intake / exhaust valves 14 (14a, 14b) are mechanically connected to variable valve mechanisms (drive devices) 15 (15a, 15b) for driving the valves.

  Next, FIG. 2 shows an example of a variable valve system including the variable valve mechanism 15 of FIG. FIG. 2 illustrates one variable valve mechanism 15 (15a, 15b) and one intake / exhaust valve 14 (14a, 14b). Moreover, the arrow in a figure has shown the flow of hydraulic oil (working fluid).

  First, the fuel injection system will be described. The fuel tank 16 is connected to a feed pump 18 through a filter 17. A relief valve (pressure adjusting valve) 19 is connected to the outlet of the feed pump 18 so that the feed pressure of the feed pump 18 is kept constant. The feed pressure is greater than normal pressure (ie, the fuel is in a pressurized state) but is significantly less than the common rail pressure described below.

  The outlet of the feed pump 18 is connected to the high pressure pump 20. As a result, the fuel in the fuel tank 16 is sucked by the feed pump 18 and then sent to the high-pressure pump 20 while maintaining a constant pressure by the relief valve 19.

  The high-pressure pump 20 is connected to the common rail 21, and fuel is pumped from the high-pressure pump 20 to the common rail 21. The common rail 21 stores high-pressure fuel having a common rail pressure of several tens to several hundreds of MPa. The common rail 21 is connected to a plurality of injectors 6, and the high-pressure fuel is always supplied from the common rail 21 to each injector 6. The common rail 21 is provided with a pressure sensor (not shown) that detects the common rail pressure. This pressure sensor is electrically connected to the ECU 22. The electromagnetic solenoid of the injector 6 is also electrically connected to the ECU 22, and its operation is controlled by the ECU 22.

  The ECU 22 is a microcontroller for comprehensively performing electrical control in the operation of the engine 1. The ECU 22 is electrically connected to a sensor that detects the operating state (crank angle, rotational speed, engine load, etc.) of the engine 1. The ECU 22 grasps the operating state of the engine 1 based on the signal from each sensor, and transmits or drives a corresponding drive signal to the electromagnetic solenoid of the injector 6 to execute or stop fuel injection from the injector 6. To do.

  Next, the variable valve mechanism 15 will be described. The variable valve mechanism 15 supplies and discharges hydraulic oil into a hydraulic control chamber (control chamber) 25 so that intake and exhaust are performed at an arbitrary timing and an arbitrary lift amount that do not depend on the rotation angle of the crankshaft without using a cam. The hydraulic valve 14 has a hydraulic (fluid pressure) type variable valve mechanism for opening and closing the valve 14 for use. Note that only one of the variable valve mechanism parts 15a, 15b of the intake or exhaust valves 14a, 14b is configured as a hydraulic variable valve mechanism part, and the other variable valve mechanism part is configured as a hydraulic mechanism. It may be constituted by a variable valve mechanism of a prior art that does not include.

  An actuator body (housing) 26 of the variable valve mechanism 15 is fixed to the cylinder head 5. A hole 27a extending along the axis is formed in the center of the actuator body 26. The stem portion 14s of the intake / exhaust valve 14 is inserted into the hole 27a in a slidable state while maintaining a sealing property. A flange portion 14g that protrudes in the radial direction of the stem portion 14s is formed around the outer periphery of the stem portion 14s at an intermediate position in the axial direction on the outer periphery of the stem portion 14s of the valve 14.

  Between the bottom surface of the flange portion 14g and the cylinder head 5, a valve spring 28 that biases the valve 14 in the valve closing direction (upward in FIG. 2) surrounds the stem portion 14s and is in a compressed state. It is installed at. A magnet 29 that attracts the valve 14 in the valve closing direction is disposed between the upper surface of the flange portion 14g and the bottom surface of the actuator body 26 so as to surround the stem portion 14s.

  On the other hand, in the hole 27a of the actuator body 26, the above-described hydraulic control chamber 25 is formed on the upper surface side of the stem portion 14s of the intake / exhaust valve 14. By controlling the pressure (hydraulic pressure) in the hydraulic control chamber 25, the opening and closing of the intake / exhaust valve 14 and the lift amount are controlled. For example, when hydraulic oil is supplied into the hydraulic control chamber 25, the intake / exhaust valve 14 is pushed in the opening direction (downward in FIG. 2), and the pushing force exceeds the urging force of the valve spring 28 and the magnet 29. And the intake / exhaust valve 14 opens. On the other hand, when the hydraulic oil is discharged from the hydraulic control chamber 25, the intake / exhaust valve 14 is closed. The bottom surface of the hydraulic control chamber 25, that is, the upper surface of the stem portion 14s is a pressure receiving surface that receives pressure from the hydraulic oil. As the hydraulic oil, for example, light oil common to the fuel of the engine 1 is used.

  The hydraulic control chamber 25 is connected to a valve unit (first operating valve) 31 through a passage 30 that extends from the inner wall surface of the hole 27 a to the outer wall surface of the actuator body 26. The valve unit 31 is connected to the outlet of the low pressure chamber 32. The low-pressure chamber 32 is a supply source of low-pressure hydraulic oil, and an outlet of the feed pump 18 (a position downstream of the relief valve 19 and upstream of the high-pressure pump 20) is connected to the inlet thereof. The electromagnetic solenoid of the valve unit 31 is electrically connected to the ECU 22, and its operation is controlled by the ECU 22.

  In addition, an inlet of a check valve (second operating valve) 33 is connected to the valve unit 31. The outlet of the check valve 33 is connected to the outlet of the feed pump 18 (a position downstream from the relief valve 19 and upstream from the high-pressure pump 20). The check valve 33 opens based on the pressure difference between the inlet side and the outlet side, and opens only when the pressure on the inlet side is higher than the pressure on the outlet side by a preset pressure. Yes. The preset pressure of the check valve 33 is higher than the above-described feed pressure and is significantly lower than the common rail pressure. Accordingly, the check valve 33 does not open when low pressure fuel is present at the inlet, but opens when high pressure fuel is present at the inlet.

  On the other hand, an operating valve (third operating valve) 35 is installed above the hydraulic control chamber 25. The operation valve 35 is a device for switching supply or stop of supply of high-pressure fuel to the hydraulic control chamber 25, and is constituted by, for example, a pressure balance control valve. The actuating valve 35 is not limited to a pressure balance type control valve, and can be variously changed. For example, it may be a spool valve.

  In the upper portion of the actuator body 26, a hole 27b having a diameter larger than that of the hole 27a is formed so as to communicate with the hole 27a. In this hole 27b, the balance valve (valve element) 36 of the actuating valve 35 moves up and down along the axial center with its axial center aligned with the axial center of the intake / exhaust valve 14. Arranged as possible. The balance valve 36 is formed in a needle shape having a diameter larger than that of the hole 27 a, for example, and a conical surface thereof faces the hydraulic control chamber 25.

  A shaft seal portion (not shown) is formed on the upper surface of the balance valve 36. A passage 38 is formed below the shaft seal portion and between the outer wall surface of the balance valve 36 and the inner wall surface of the hole 27b. The passage 38 is connected to the hydraulic control chamber 25 by opening the balance valve 36 (moving upward).

  A valve control chamber 39 is formed above the shaft seal portion. The upper surface of the balance valve 36 is a pressure receiving surface on which the hydraulic oil pressure in the valve control chamber 39 is applied. These passages 38 and the valve control chamber 39 are connected to the common rail 21 which is a supply source of high-pressure hydraulic oil, and high-pressure fuel with a common rail pressure is always supplied.

  A spring 41 that biases the balance valve 36 in the valve closing direction is installed in the valve control chamber 39 in a compressed state. The valve control chamber 39 is connected to the return passage 43 via the orifice 42. An opening / closing valve 44 for opening and closing the orifice 42 is installed above the orifice 42 so as to be movable up and down. Above the on-off valve 44, an electromagnetic solenoid 45 that controls the up-down movement of the on-off valve 44 and a spring 46 that biases the on-off valve 44 in a closing direction are installed. The electromagnetic solenoid 45 is electrically connected to the ECU 22 and its operation is controlled by the ECU 22. Normally, when the electromagnetic solenoid 45 is off, the opening / closing valve 44 is pressed downward by the spring 46 and the orifice 42 is closed. On the other hand, when the electromagnetic solenoid 45 is on, the on-off valve 44 rises against the biasing force of the spring 46 and the orifice 42 is opened. Instead of the electromagnetic solenoid 45, a piezoelectric element (piezo actuator), a giant magnetostrictive element, or the like may be used.

  Next, an operation example of the variable valve mechanism 15 will be described.

  First, when the intake / exhaust valve 14 is changed from the closed state to the open state, the valve unit 31 is closed (the electromagnetic solenoid of the valve unit 31 is turned off), and the operation valve 35 is opened (electromagnetic). The solenoid 45 is turned on). As a result, the on-off valve 44 is raised, the orifice 42 is opened, and the hydraulic oil in the valve control chamber 39 flows through the orifice 42 to the return passage 43 side. For this reason, since the pressure in the valve control chamber 39 becomes low, the balance valve 36 rises and is separated from the valve seat. As a result, the passage 38 communicates with the hydraulic control chamber 25, and the hydraulic control chamber passes through the passage 38 from the common rail 21 side. High pressure hydraulic oil flows through 25. The pressure receiving surface of the intake / exhaust valve 14 is pressed by the high-pressure hydraulic oil.

  Next, when no hydraulic oil enters or leaves the hydraulic control chamber 25, the intake / exhaust valve 14 is maintained stationary. As a result, the intake / exhaust valve 14 can be kept open for an arbitrary period.

Next, when the intake / exhaust valve 14 is closed, the valve 35 is opened (the electromagnetic solenoid of the valve unit 31 is turned on) with the operation valve 35 closed (the electromagnetic solenoid 45 is turned off). To do). As a result, the on-off valve 44 is lowered, the orifice 42 is closed, and the discharge of hydraulic oil from the valve control chamber 39 is stopped. For this reason, since the pressure in the valve control chamber 39 gradually increases, the balance valve 36 is lowered and seated. On the other hand, the hydraulic oil in the hydraulic control chamber 25 flows to the valve unit 31 through the passage 30. At this time, since the valve opening pressure of the check valve 33 is set to a value lower than the common rail pressure, the check valve 33 is automatically opened, and the hydraulic oil is on the outlet side of the feed pump 18 (downstream of the relief valve 19). Thus, the gas is discharged to a position upstream of the high-pressure pump 20. For this reason, the pressure in the hydraulic control chamber 25 decreases, and the intake / exhaust valve 14 is raised and closed by the urging force of the valve spring 28 and the magnet 29.

  Next, a method for controlling the engine 1 according to the present embodiment will be described with reference to FIGS. 1, 2, and 3.

  First, in the engine 1 of the present embodiment, as shown in step 100 of FIG. 3, the intake port 7 (or the exhaust port 8) in the cylinder 2 is opened at the opening timing of the intake or exhaust valves 14a and 14b. The internal pressure is measured by pressure sensors 2b and 11a (11b), respectively.

  Subsequently, as shown in step 101 of FIG. 3, based on the measured pressure, a differential pressure between the pressure in the cylinder 2 and the pressure in the intake port 7 (or the exhaust port 8) is calculated.

Subsequently, as shown in step 102 of FIG. 3, the valve thrust required to obtain the set lift amount of the intake or exhaust valves 14a and 14b is calculated using the calculated differential pressure. That is, what is set to the value of the valve thrust of the intake or exhaust valves 14a and 14b in the pressure state (calculated differential pressure) of the actual intake or exhaust valves 14a and 14b? It is calculated whether the lift amount can be set to the set lift amount (required value).

  Subsequently, as shown in step 103 of FIG. 3, the required supply amount of hydraulic oil supplied into the hydraulic control chamber 25 is calculated using the calculated valve thrust. That is, the supply amount of hydraulic oil necessary to realize the calculated valve thrust is calculated.

  Subsequently, as shown in step 104 of FIG. 3, a period during which the hydraulic oil is supplied into the hydraulic control chamber 25 is determined using the characteristic map, using the calculated required supply amount of the hydraulic oil. That is, how much time is required to supply the calculated required supply amount of hydraulic oil into the hydraulic control chamber 25 is determined by a characteristic map created in advance.

  Thereafter, the hydraulic oil is supplied to the hydraulic control chamber 25 in accordance with the required hydraulic oil supply amount and supply period calculated in this way, thereby opening the intake or exhaust valves 14a and 14b with the set lift amount.

  The valve thrust in the opening operation of the intake / exhaust valve 14 by the variable valve mechanism 15 is obtained by adding the following mechanical physical formula to the logic of the ECU 22. This will be described with reference to FIG. 4 and FIG. 4 is an enlarged cross-sectional view of the main part showing the pressure state of the engine 1 in FIG. 1, and FIG. 5 is an enlarged cross-sectional view of the main part showing the pressure state of the variable valve mechanism 15 in FIG. Here, the intake valve 14a will be described as an example.

As shown in FIG. 4, the force from the intake port 7 side to the intake valve 14a is Fp, the force from the cylinder 2 to the intake valve 14a is Fc, and the hydraulic control as shown in FIG. The force that the high-pressure hydraulic oil in the chamber 25 pushes the intake valve 14a is Fo, the attractive force of the magnet 29 is Fm, and the reaction force of the valve spring 28 is Fs.

In this case, if the force applied to the intake valve 14a in the valve opening direction is Fv, Fv is expressed by the following equation.
Fv = Fo− (Fc−Fp) − (Fm + Fs) (1)

Here, if the pressure of the high-pressure hydraulic oil supplied to the hydraulic control chamber 25 is Po, and the diameter of the upper surface of the intake valve 14a (the upper surface of the stem portion 14s) facing the hydraulic control chamber 25 is Φ1, Fo is expressed as follows.
Fo = Po × (Φ1 / 2) ² × π (2)

Further, (Fc−Fp) on the right side of the expression (1) uses the pressures Pc and Pp measured by the pressure sensors 2b and 11a in the cylinder 2 and the intake port 7, and the seat diameter of the intake valve 14a (valve head) (Diameter) is represented by the following equation.
Fc−Fp = (Pc−Pp) × (Φ2 / 2) ² × π (3)

  However, since (Pc−Pp) fluctuates during the valve opening process of the intake valve 14a, it is necessary to create a characteristic map by an intake / exhaust system simulation such as a wave (WAVE).

  Further, regarding the Pc at the time of valve opening, the responsiveness of the pressure sensor is taken into consideration, and the Pc at the time of valve opening is calculated from the pressure immediately before the valve opening timing as a polytropic change.

For the last term on the right side of equation (1), (Fm + Fs), a characteristic map of Fm is created by investigating the attractive force of the magnet 29 in advance, the spring constant of the valve spring 28 is k, and when installed By measuring the length of, the following equation is obtained.
Fs = k × (lift amount + mounting length) (4)

  By applying the above physical formula to Formula (1), Fv with respect to the lift amount in the valve opening process of the intake valve 14a can be obtained.

Thus, the valve thrust W (J) necessary for opening the intake valve 14a to the set lift amount L is expressed by the following equation.

  The above physical formula is incorporated in the ECU 22 to calculate the supply amount of the high-pressure hydraulic oil necessary for obtaining the calculated required valve thrust, and further, the required high-pressure hydraulic oil supply period is determined based on the characteristic map created in advance. To do.

  Thus, according to the engine 1 of the present embodiment, the pressure applied before and after the intake / exhaust valve 14 (the pressure in the intake port 7 or the exhaust port 8 and the pressure in the cylinder 2) is taken into consideration. Since the valve thrust can be set, the control accuracy of the lift amount of the intake / exhaust valve 14 in the hydraulic variable valve mechanism 15 can be improved. For this reason, the area | region of premixed diesel combustion can be expanded. Further, by advancing the valve opening timing of the exhaust valve 14b until the combustion period, high-temperature exhaust gas can be supplied to the exhaust post-treatment device, so that the temperature of the exhaust post-treatment device can be quickly raised. Can do. Furthermore, since the accuracy of the intake air amount and the intake air composition can be improved, the combustion efficiency can be improved. Therefore, exhaust gas can be reduced and fuel consumption can be improved.

  An internal combustion engine control method and an internal combustion engine according to the present invention measure the pressure of an intake / exhaust port and the pressure in a cylinder, and calculate a valve thrust required to realize a set lift amount in the pressure state. As a result, it is possible to improve the control accuracy of the lift amount of the intake valve, the exhaust valve, or both of the valves in the fluid pressure internal combustion engine, which can be used for a control method of an internal combustion engine such as an automobile and the internal combustion engine.

1 Diesel engine (internal combustion engine)
2 cylinders
2b Pressure sensor (first pressure sensor)
3 Piston 4 Cavity (combustion chamber)
7 Intake port (inlet)
8 Exhaust port (exhaust port)
9 Intake pipe 10 Exhaust pipe 11a, 11b Pressure sensor (second pressure sensor)
14a Intake valve 14b Exhaust valve 14s Stem portion 14g Fence portions 15, 15a, 15b Variable valve mechanism portion 16 Fuel tank 18 Feed pump 20 High-pressure pump 22 Electronic control unit, ECU (control unit)
25 Hydraulic control room (control room)
26 Actuator bodies 27a, 27b Hole 30 Passage 31 Valve unit (first actuating valve)
32 Low pressure chamber 33 Check valve (second operating valve)
35 Actuation valve (3rd actuation valve)
36 Balance valve (valve)
38 Passage 39 Valve control room

Claims (4)

In a control method for an internal combustion engine comprising a drive device that opens and closes valves for intake, exhaust, or both at an arbitrary timing independent of a rotation angle of a crankshaft by supplying a working fluid to a control chamber.
At the opening timing of the intake or exhaust valve,
Measuring the pressure in the cylinder and the intake / exhaust port of the internal combustion engine;
Calculating a differential pressure between the pressure in the cylinder and the pressure in the intake and exhaust ports based on the measured pressure;
Using the differential pressure, it is necessary to obtain the force applied in the valve opening direction with respect to the lift amount in the valve opening process of the intake or exhaust valve, and to obtain the set lift amount of the intake or exhaust valve. Calculating the valve thrust from the following equation ;
Calculating the required supply amount of the working fluid using the calculated valve thrust;
And a step of opening the intake or exhaust valve by the set lift amount by supplying the working fluid to the control chamber according to the calculated required supply amount of the working fluid.

W: Valve thrust, Fv: Force applied in the valve opening direction, L: Set lift amount   A step of determining a period during which the working fluid is supplied into the control chamber by using a characteristic map, using the calculated required supply amount of the working fluid at a valve opening timing of the intake or exhaust valve; The method for controlling an internal combustion engine according to claim 1. In an internal combustion engine provided with a drive device that opens and closes valves for intake, exhaust, or both at an arbitrary timing that does not depend on the rotation angle of the crankshaft by supplying a working fluid to the control chamber.
A first pressure sensor for measuring a pressure in a cylinder of the internal combustion engine;
A second pressure sensor for measuring the pressure at the intake and exhaust ports of the internal combustion engine;
At the opening timing of the intake or exhaust valve, a differential pressure between the pressure in the cylinder measured by the first and second pressure sensors and the pressure at the intake and exhaust ports is calculated, and this differential pressure is used. Then, the force applied in the valve opening direction with respect to the lift amount in the valve opening process of the intake or exhaust valve is obtained, and the valve thrust required to obtain the set lift amount of the intake or exhaust valve is obtained from the following equation: Calculating the required supply amount of the working fluid using the calculated valve thrust, and supplying the working fluid to the control chamber according to the calculated required supply amount of the working fluid. An internal combustion engine comprising a control unit that opens a valve for use or exhaust with the set lift amount.

W: Valve thrust, Fv: Force applied in the valve opening direction, L: Set lift amount   The control unit further uses a characteristic map to indicate a period during which the working fluid is supplied into the control chamber using the calculated required supply amount of the working fluid at the opening timing of the intake or exhaust valve. The internal combustion engine according to claim 3, comprising a function for determining.

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