JP2004360459A - Valve timing control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a valve timing control device for an internal combustion engine capable of holding both a combustion state and exhaust gas characteristics in excellent states by accurately and finely controlling intake air quantity. <P>SOLUTION: This valve timing control device 1 of the internal combustion engine variably controlling a valve closing timing relative to the valve opening timing of an intake valve 6 through a variable intake air valve driving device 40 comprises an ECU2. The ECU2 determines the base value θmsi_base of a target auxiliary intake air cam phase according to the requested drive torque TRQ_eng of the internal combustion engine 3 (step 74) and calculates a controlled input DUTY_msi into the variable intake air valve drive device 40 so that a cylinder intake air quantity Gcyl can be converged to a target intake air quantity Gcyl_cmd and the auxiliary intake air cam phase θmsi can be arrested by the base value θmsi_base (steps 75 and 78). <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a valve timing control device for an internal combustion engine that controls the valve timing of an intake valve of the internal combustion engine.
[0002]
[Prior art]
BACKGROUND ART Conventionally, as a valve timing control device for an internal combustion engine that controls the valve timing of an intake valve of an internal combustion engine, for example, a device described in Patent Document 1 is known. The internal combustion engine includes a rocker arm for opening and closing an intake valve, two low-load and high-load cams provided for each intake valve, and a low-load cam or a high-load cam for driving the rocker arm. And an actuator for switching to. The two cams are arranged on the camshaft adjacent to each other, and the cam profile of the low-load cam has the same valve opening timing and the valve closing timing is later than that of the high-load cam. It is formed as follows. Further, the rocker arm is provided on the rocker shaft so as to be slidable in the axial direction, and the actuator is slid by an actuator between a position where one end abuts the low load cam and a position where the one end abuts the high load cam. Is driven. That is, the cam that drives the intake valve is switched to the low-load cam or the high-load cam by the actuator.
[0003]
In this valve timing control device, by controlling the actuator, the cam that drives the intake valve becomes a low-load cam when the load of the internal combustion engine is in a low-load region, and becomes a high-load cam when the load of the internal combustion engine is in a high-load region. Accordingly, the intake valve closing timing is switched so that the closing timing of the intake valve is later in the low load range than in the high load range. The reason for switching the valve closing timing is as follows. That is, the amount of air to be taken into the cylinder is smaller in the low load range than in the high load range, and if this is performed by reducing the opening of the throttle valve, due to the decrease in the negative pressure in the intake pipe, Pumping loss occurs, leading to deterioration of fuel efficiency. In order to avoid this, the valve timing control device switches the valve closing timing of the intake valve in the low load range so as to be later than in the high load range, so that the intake air blows back from the cylinder. Therefore, the amount of intake air is reduced without reducing the opening of the throttle valve.
[0004]
Conventionally, as a valve timing control device for an internal combustion engine that controls the valve timing of an intake valve of an internal combustion engine, for example, one described in Patent Document 2 is known. In this valve timing control device, the phase of the intake cam that drives the intake valve is controlled so as to change with respect to the crankshaft, so that the intake valve keeps its opening time constant, The valve opening and closing timing is changed.
[0005]
[Patent Document 1]
Japanese Utility Model Publication No. 56-9045 (pages 1-2, FIG. 1-4)
[Patent Document 2]
JP-A-7-269380 (pages 2-3, FIG. 7)
[0006]
[Problems to be solved by the invention]
According to the valve timing control device of Patent Document 1, the cam for driving the intake valve is merely switched to a low-load cam or a high-load cam. It is only possible to switch to two timings determined by the cam profile. Therefore, the intake air amount cannot be precisely and precisely controlled, and if the intake air amount is excessive or insufficient, the combustion state may become unstable, the fuel efficiency may deteriorate, or the exhaust gas characteristics may deteriorate. . When the valve timing of the intake valve is controlled by the valve timing control device of Patent Document 2 to control the intake air amount, the valve opening and closing are performed in a state where the opening time of the intake valve is kept constant. Since the valve closing timing is changed, the intake air amount cannot be finely controlled by changing the valve overlap, and at the same time, the internal EGR amount changes, which may lead to deterioration of the combustion state and the exhaust gas characteristics. There is.
[0007]
The present invention has been made in order to solve the above-mentioned problems, and it is possible to precisely and precisely control an intake air amount, thereby maintaining an excellent combustion state and an exhaust gas characteristic in an internal combustion engine. It is an object to provide a valve timing control device.
[0008]
[Means for Solving the Problems]
In order to achieve this object, the invention according to claim 1 variably controls the valve closing timing with respect to the valve opening timing of the intake valve 6 via a variable valve timing device (variable intake valve driving device 40). A valve timing control device 1 for the internal combustion engine 3, a load detecting means (ECU 2, a crank angle sensor 20, an accelerator opening sensor 35, step 11) for detecting a load (required drive torque TRQ_eng) of the internal combustion engine 3; Valve closing timing determining means (ECU 2, first SPAS controller 221, step 74) for determining the valve closing timing of intake valve 6 (basic value θmsi_base of target auxiliary intake cam phase) according to the determined load of the internal combustion engine. Valve timing variable device (variable intake valve driving device 40) according to the closed valve timing of intake valve 6 Control controlling means (ECU 2, step 75, 78) and, characterized in that it comprises a.
[0009]
According to this valve timing control device for an internal combustion engine, the closing timing of the intake valve is determined by the valve closing timing determining means according to the detected load of the internal combustion engine, and the variable valve timing device is controlled by the controlling means. The control is performed in accordance with the determined closing timing of the intake valve, whereby the amount of intake air taken into the internal combustion engine via the intake valve is controlled. As described above, the intake air amount is controlled according to the load of the internal combustion engine, so that the intake air amount can be controlled more precisely and more precisely than in the past, and excess or deficiency of the intake air amount can be avoided. As a result, both the combustion state and the exhaust gas characteristics can be maintained in a favorable state.
[0010]
According to a second aspect of the present invention, in the valve timing control apparatus 1 for the internal combustion engine 3 according to the first aspect, the valve closing timing determining means may be configured such that the load of the internal combustion engine is in a predetermined first load region (TRQ_idle ≦ TRQ_eng <TRQott). , The closing timing of the intake valve is determined to be later than a predetermined timing at which the expansion ratio during the combustion cycle of the internal combustion engine 3 becomes equal to the compression ratio (θmsi_base <θmsiott), and the load of the internal combustion engine is reduced to a predetermined value. When it is in a predetermined second load range (TRQott <TRQ_eng <TRQ4) higher than the first load range, the closing timing of the intake valve 6 is determined to be earlier than the predetermined timing (θmsiott <θmsi_base). And
[0011]
According to this valve timing control device for an internal combustion engine, when the load of the internal combustion engine is in the predetermined first load range, the closing timing of the intake valve is such that the expansion ratio during the combustion cycle of the internal combustion engine is equal to the compression ratio. Since the timing is determined to be later than the predetermined timing (ie, the valve closing timing in the Otto cycle operation), the internal combustion engine can be operated in a high expansion ratio cycle (ie, a Miller cycle) in which the expansion ratio is higher than the compression ratio. . Thus, by setting the predetermined first load region to a low load region where pumping loss due to throttle valve throttling becomes a problem, it is not necessary to throttle the intake air amount with the throttle valve in the low load region. Thus, while avoiding pumping loss, the intake air amount can be set to an appropriate value corresponding to a low load, and fuel efficiency can be improved. In addition to this, in general, when the intake air temperature or the engine temperature is low, if the valve closing timing of the intake valve is set to a timing earlier than the above-mentioned predetermined timing in a low load region, adiabatic expansion of the air-fuel mixture in the cylinder may occur. Due to the lowering of the in-cylinder temperature, liquefaction of the fuel may occur, and the combustion state may become unstable. On the other hand, according to the valve timing control device, as described above, in the predetermined first load range, the closing timing of the intake valve is determined to be later than the predetermined timing. By setting the load region to the low load region where liquefaction of fuel occurs, a better combustion state can be ensured than at the earlier timing.
[0012]
Also, in general, when the closing timing of the intake valve is set to a predetermined timing at which the expansion ratio becomes equal to the compression ratio in a high load region, fuel blows back into the intake manifold and stays in the intake manifold. When the amount of fuel increases or the amount of fuel attached to the inner wall of the intake manifold increases, control accuracy such as air-fuel ratio control and torque control, particularly control accuracy in a transient operation state, is reduced. More specifically, the air-fuel ratio of the air-fuel mixture shifts to the rich side, which may cause an unnecessary increase in torque and an increase in unburned HC in exhaust gas. In addition, the fuel that has been blown back adheres to a device such as an intake valve in a carbonized state, which may shorten the life of the device of the intake system. The above problems are more remarkable because, in a high load range, when the closing timing of the intake valve is set to a timing later than the predetermined timing, the amount of fuel blown back into the intake manifold increases. Become. For example, when the degree of enrichment of the air-fuel mixture becomes excessive, misfire of the internal combustion engine may be caused. On the other hand, according to this valve timing control device, in the predetermined second load range where the load of the internal combustion engine is higher than the predetermined first load range, the closing timing of the intake valve is earlier than the predetermined timing. When the predetermined second load region is set to a high load region in which the fuel blows back as described above, the fuel is blown into the intake manifold in such a high load region. No return occurs. As a result, the control accuracy of the air-fuel ratio control and the torque control in a high load region can be improved, and in particular, the control accuracy in a transient operation state can be significantly improved. As a result, exhaust gas characteristics and operability can be improved, and the life of the intake system device can be extended.
[0013]
According to a third aspect of the present invention, in the valve timing control device 1 of the internal combustion engine 3 according to the first or second aspect, the variable valve timing device is a hydraulically driven variable valve timing device driven by supplying hydraulic pressure. The control means controls the hydraulic pressure Psd supplied to the hydraulically driven variable valve timing device.
[0014]
According to this valve timing control device for an internal combustion engine, since the variable valve timing device is constituted by a hydraulic drive type driven by supply of hydraulic pressure, for example, the valve body of the intake valve is controlled by the electromagnetic force of a solenoid. The intake valve can be reliably opened and closed even in a higher load range as compared with the case of using a variable valve timing device of a driving type, and the power consumption can be reduced and the operation sound of the intake valve can be reduced. .
[0015]
The invention according to claim 4 is the valve timing control device 1 for the internal combustion engine 3 according to claim 1 or 2, wherein the variable valve timing device is configured to be able to change the valve lift amount of the intake valve 6 freely. Features.
[0016]
According to this valve timing control device for an internal combustion engine, the variable valve timing device is configured to be able to change the valve lift amount of the intake valve. Therefore, for example, by controlling the lift amount to a smaller value side, the combustion chamber is controlled. The flow velocity of the intake air flowing into the cylinder can be increased, and the in-cylinder flow can be further increased. Thereby, the combustion efficiency can be improved.
[0017]
According to a fifth aspect of the present invention, in the valve timing control device 1 for the internal combustion engine 3 according to the first aspect, the variable valve timing device is configured to be capable of changing a valve lift amount of the intake valve 6, and a valve of the intake valve 6. When the load of the internal combustion engine 3 is in a predetermined third load region (TRQ_eng <TRQott) lower than the predetermined load, the valve lift determining means (ECU2) determines the lift amount to be smaller than when the load is equal to or higher than the predetermined load. And the valve closing timing determining means sets the valve closing timing of the intake valve 6 when the load of the internal combustion engine 3 is in the predetermined third load range so that the expansion ratio during the combustion cycle of the internal combustion engine 3 becomes the compression ratio. The control means determines the timing earlier than the predetermined timing at which the valve timing becomes equal, and determines the valve timing according to the determined valve closing timing and the valve lift amount of the intake valve 6. And controlling the ring variable device.
[0018]
As described above, when the intake air temperature or the engine temperature is low, in the low load region, the closing timing of the intake valve is set to a timing earlier than the predetermined timing at which the expansion ratio during the combustion cycle of the internal combustion engine becomes equal to the compression ratio. If it is set, fuel may be liquefied due to a decrease in cylinder temperature due to adiabatic expansion of the air-fuel mixture in the cylinder, and the combustion state may be unstable. On the other hand, according to this valve timing control device, when the valve lift amount of the intake valve is in the predetermined third load region where the load on the internal combustion engine is smaller than the predetermined load, the valve lift amount is smaller than when the load is equal to or more than the predetermined load. Therefore, the flow rate of the intake air flowing into the combustion chamber is increased as compared with the case where the load is equal to or more than the predetermined load, and the in-cylinder flow is increased, so that the combustion can be accelerated. Therefore, by setting the predetermined third load region as a low load region, liquefaction of the fuel can be avoided even in the low load region, whereby the combustion state can be stabilized.
[0019]
According to a sixth aspect of the present invention, in the valve timing control device 1 of the internal combustion engine 3 according to the fourth or fifth aspect, the variable valve timing device is rotatably supported by a pivot (pin 51c) and pivots. Between the first and second intake camshafts, the first and second intake camshafts (main and sub intake camshafts 41 and 42) rotating at the same rotational speed as the intake rocker arm 51 for driving the intake valve 6 to open and close by the rotation of the intake camshaft. And a first intake camshaft (main intake camshaft 41) for changing a relative phase (sub intake cam phase θmsi) of the intake camshaft (main intake camshaft 41). A first intake cam (main intake cam 43) that rotates the intake rocker arm 51 about a pivot point by rotating with the rotation of the camshaft; A second intake cam (sub intake cam 44) that is provided on the (sub intake camshaft 42) and that rotates with the rotation of the second intake camshaft to move the rotation fulcrum of the intake rocker arm 51. It is characterized by the following.
[0020]
According to this valve timing control device for an internal combustion engine, in the variable valve timing device, the first rocker rotates along with the rotation of the first camshaft, thereby rotating the intake rocker arm around the rotation fulcrum. The intake valve is driven to open and close. At this time, the second cam rotates along with the rotation of the second camshaft to move the rotation fulcrum of the intake rocker arm, so that the valve lift of the intake valve can be freely changed, and furthermore, Since the relative phase between the first and second intake camshafts is changed by the variable intake cam phase mechanism, both the closing timing of the intake valve and the valve lift can be freely changed. That is, by using two cams, two camshafts, and a variable cam phase mechanism, it is possible to realize a variable valve timing device that can freely change the valve closing timing and the valve lift of the intake valve.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a valve timing control device for an internal combustion engine according to an embodiment of the present invention will be described with reference to the drawings. FIGS. 1 and 2 show a schematic configuration of an internal combustion engine (hereinafter, referred to as “engine”) 3 to which a valve timing control device (hereinafter, simply referred to as “control device”) 1 of the present embodiment is applied, and FIG. 1 shows a schematic configuration of a control device 1. As shown in FIG. 3, the control device 1 includes an ECU 2. The ECU 2 performs various control processes including a valve timing control of the intake valve 6 according to an operation state of the engine 3 as described later. Execute
[0022]
The engine 3 is an in-line four-cylinder gasoline engine mounted on a vehicle (not shown), and includes first to fourth four cylinders # 1 to # 4 (see FIG. 5). Further, in the engine 3, a main fuel injection valve 4 and a spark plug 5 are provided for each cylinder (only one is shown), and each of the main fuel injection valve 4 and the spark plug 5 is a cylinder head. 3a. Each main fuel injection valve 4 is connected to the ECU 2, and the amount of fuel injection and the timing of fuel injection are controlled by a control input from the ECU 2, whereby fuel is directly injected into the combustion chamber of the corresponding cylinder.
[0023]
Each ignition plug 5 is also connected to the ECU 2, and discharges when a high voltage is applied from the ECU 2 at a timing corresponding to the ignition timing, thereby burning the air-fuel mixture in the combustion chamber.
[0024]
Further, the engine 3 is provided for each cylinder and is provided with an intake valve 6 and an exhaust valve 7 for opening and closing an intake port and an exhaust port, respectively, and a variable type for opening and closing the intake valve 6 and simultaneously changing its valve timing and valve lift amount. The apparatus includes an intake valve driving device 40 and a variable exhaust valve driving device 90 that opens and closes the exhaust valve 7 and changes the valve timing and the valve lift amount at the same time. Details of the variable intake driving device 40 and the variable exhaust valve driving device 90 will be described later. The intake valve 6 and the exhaust valve 7 are urged in the valve closing direction by valve springs 6a, 7a, respectively.
[0025]
On the other hand, a magnet rotor 20a is attached to a crankshaft 3b of the engine 3. The magnet rotor 20a, together with the MRE pickup 20b, constitutes a crank angle sensor 20 (load detecting means). The crank angle sensor 20 outputs a CRK signal and a TDC signal, both of which are pulse signals, to the ECU 2 as the crankshaft 3b rotates.
[0026]
As the CRK signal, one pulse is output every predetermined crank angle (for example, 30 deg). The ECU 2 calculates the rotation speed NE of the engine 3 (hereinafter referred to as “engine rotation speed”) according to the CRK signal. Further, the TDC signal is a signal indicating that the piston 3c of each cylinder is at a predetermined crank angle position slightly before the TDC position in the intake stroke, and every predetermined crank angle (180 deg in the example of the present embodiment). Is output.
[0027]
The intake pipe 8 of the engine 3 is provided with a turbocharger device 10, an intercooler 11, a fuel evaporative cooling device 12, a throttle valve mechanism 16, and the like in this order from the upstream side.
[0028]
The turbocharger device 10 includes a compressor blade 10a housed in a compressor housing in the middle of the intake pipe 8, a turbine blade 10b housed in a turbine housing in the middle of the exhaust pipe 9, and two blades 10a and 10b. , And a wastegate valve 10d.
[0029]
In the turbocharger device 10, when the turbine blade 10b is driven to rotate by the exhaust gas in the exhaust pipe 9, the compressor blade 10a integrated therewith is also rotated, so that the intake air in the intake pipe 8 is pressurized. You. That is, a supercharging operation is performed.
[0030]
The wastegate valve 10d opens and closes a bypass exhaust passage 9a that bypasses the turbine blade 10b of the exhaust pipe 9, and is constituted by an electromagnetic control valve connected to the ECU 2 (see FIG. 3). The opening of the wastegate valve 10d changes according to the control input Dut_wg from the ECU 2, thereby changing the flow rate of the exhaust gas flowing through the bypass exhaust passage 9a, in other words, the flow rate of the exhaust gas driving the turbine blade 10b. . Thereby, the supercharging pressure Pc by the turbocharger device 10 is controlled.
[0031]
On the other hand, an airflow sensor 21 is provided upstream of the compressor blade 10a of the intake pipe 8. The air flow sensor 21 is configured by a hot wire air flow meter, and outputs a detection signal indicating an intake air amount Gth (hereinafter, referred to as “TH passage intake air amount”) Gth passing through the throttle valve 17 to be described later to the ECU 2.
[0032]
The intercooler 11 is a water-cooled type, and cools the intake air whose temperature has increased due to the supercharging operation (pressurizing operation) of the turbocharger device 10 when the intake air passes through the inside of the intercooler 11.
[0033]
Further, a supercharging pressure sensor 22 is provided between the intercooler 11 of the intake pipe 8 and the fuel evaporative cooling device 12. The supercharging pressure sensor 22 is configured by a semiconductor pressure sensor or the like, and outputs a detection signal representing the intake pressure in the intake pipe 8 pressurized by the turbocharger device 10, that is, a supercharging pressure Pc (absolute pressure) to the ECU 2. I do.
[0034]
On the other hand, the fuel evaporative cooling device 12 evaporates the fuel to generate the air-fuel mixture and at the same time lowers the temperature of the intake air, and is provided in the middle of the intake pipe 8 as shown in FIG. The housing 13 includes a housing 13, a large number of lipophilic film plates 14 (only six are shown) housed in the housing 13 in parallel with each other and at a predetermined interval, an auxiliary fuel injection valve 15 and the like.
[0035]
The auxiliary fuel injection valve 15 is connected to the ECU 2, and its fuel injection amount and fuel injection timing are controlled by a control input from the ECU 2, thereby injecting fuel toward a large number of lipophilic film plates 14. . As will be described later, the total fuel injection amount TOUT to be injected from both the sub fuel injection valve 15 and the main fuel injection valve 4 is determined by the ECU 2 according to the operating state of the engine 3, and The ratio of the fuel injection amount from the main fuel injection valve 4 to the fuel injection amount TOUT (main fuel injection rate Rt_Pre described later) and the ratio of the fuel injection amount from the sub fuel injection valve 15 to the operating state of the engine 3 Determined accordingly. On the surface of the lipophilic film plate 14, a lipophilic film having an affinity for fuel is formed.
[0036]
With the above configuration, in the fuel vaporization cooling device 12, the fuel injected from the auxiliary fuel injection valve 15 is thinned on the surface of each lipophilic film plate 14 due to its lipophilicity, and then vaporized by the heat of the intake air. Thereby, an air-fuel mixture is generated, and the intake air is cooled by the heat of vaporization at that time. Due to the cooling effect of the fuel vaporization cooling device 12, the charging efficiency can be increased and the knocking limit of the engine 3 can be increased. For example, at the time of high-load operation of the engine 3, the limit ignition timing at which knocking starts to occur can be extended toward the advance side by a predetermined crank angle (for example, 2 deg), thereby improving the combustion efficiency. it can.
[0037]
The above-described throttle valve mechanism 16 includes a throttle valve 17, a TH actuator 18 for opening and closing the throttle valve 17, and the like. The throttle valve 17 is provided rotatably in the middle of the intake pipe 8, and changes the TH-passing intake air amount Gth according to a change in the opening accompanying the rotation. The TH actuator 18 is a combination of a motor connected to the ECU 2 and a gear mechanism (both not shown). The TH actuator 18 controls the opening degree of the throttle valve 17 by being controlled by a control input DUTY_th described later from the ECU 2. Change.
[0038]
The throttle valve 17 is provided with two springs (both not shown) for urging the throttle valve 17 in the valve opening direction and the valve closing direction, respectively. Is maintained at a predetermined initial opening TH_def when the control input DUTY_th is not input to the TH actuator 18. The initial opening TH_def is set to a value (for example, 7 °) that is close to the fully closed state and that can secure the intake air amount necessary for starting the engine 3.
[0039]
Further, a throttle valve opening sensor 23 composed of, for example, a potentiometer is provided near the throttle valve 17 of the intake pipe 8. The throttle valve opening sensor 23 outputs a detection signal representing the actual opening TH of the throttle valve 17 (hereinafter referred to as “throttle valve opening”) to the ECU 2.
[0040]
Further, a portion of the intake pipe 8 downstream of the throttle valve 17 is a surge tank 8a, and the surge tank 8a is provided with an intake pipe absolute pressure sensor 24. The intake pipe absolute pressure sensor 24 is composed of, for example, a semiconductor pressure sensor, and outputs a detection signal indicating an absolute pressure (hereinafter, referred to as “intake pipe absolute pressure”) PBA in the intake pipe 8 to the ECU 2.
[0041]
On the other hand, on the downstream side of the turbine blade 10b of the exhaust pipe 9, first and second catalytic devices 19a and 19b are provided in order from the upstream side. NOx, HC and CO are purified.
[0042]
An oxygen concentration sensor (hereinafter referred to as “O2 sensor”) 26 is provided between the first and second catalyst devices 19a and 19b. The O2 sensor 26 is composed of zirconia and platinum electrodes, and outputs a detection signal to the ECU 2 based on the oxygen concentration in the exhaust gas downstream of the first catalyst device 19a.
[0043]
Further, an LAF sensor 25 is provided between the turbine blade 10 b of the exhaust pipe 9 and the first catalyst device 19. The LAF sensor 25 is configured by combining a sensor similar to the O2 sensor 26 and a detection circuit such as a linearizer, and detects the oxygen concentration in the exhaust gas in a wide range of the air-fuel ratio from a rich region to a lean region. It detects linearly and outputs a detection signal proportional to the oxygen concentration to the ECU 2. The ECU 2 executes air-fuel ratio control based on the detection signals of the LAF sensor 25 and the O2 sensor 26.
[0044]
Next, the above-described variable intake valve driving device 40 (variable valve timing device) will be described. As shown in FIGS. 2, 5, and 6, the variable intake valve driving device 40 includes a main intake camshaft 41 and a sub intake camshaft 42 (first and second intake camshafts) for driving intake valves. An intake valve driving mechanism 50 (only one is shown), which is provided for each cylinder, and drives the opening and closing of the intake valve 6 with the rotation of the main and sub intake camshafts 41 and 42; A variable auxiliary intake cam phase mechanism 70 (variable intake cam phase mechanism), three inter-intake cam phase variable mechanisms 80, and the like are provided.
[0045]
The main intake camshaft 41 is rotatably attached to the cylinder head 3a, and extends along the direction in which the cylinders are arranged. The main intake camshaft 41 includes a main intake cam 43 (first intake cam) provided for each cylinder, a sprocket 47 provided at one end, and a main intake cam 43 and a sprocket 47 for the first cylinder # 1. And a main gear 45 provided therebetween. The main intake cam 43, the main gear 45, and the sprocket 47 are all mounted on the main intake camshaft 41 so as to rotate coaxially and integrally. The sprocket 47 is connected to the crankshaft 3b via a timing chain 48, so that the main intake camshaft 41 rotates clockwise in FIG. 6 (indicated by an arrow Y1 in FIG. 6) every two rotations of the crankshaft 3b. Direction).
[0046]
The variable main intake cam phase mechanism 60 is provided at an end of the main intake camshaft 41 on the sprocket 47 side. The variable main intake cam phase mechanism 60 controls the relative phase of the main intake camshaft 41 with respect to the sprocket 47, that is, the relative phase of the main intake camshaft 41 with respect to the crankshaft 3b (hereinafter referred to as “main intake cam phase”) θmi. Is steplessly changed to the advance side or the retard side, and the details will be described later.
[0047]
Further, a main intake cam angle sensor 27 is provided at an end of the main intake camshaft 41 opposite to the sprocket 47. The main intake cam angle sensor 27 is composed of a magnet rotor and an MRE pickup similarly to the crank angle sensor 20, and transmits a main intake cam signal, which is a pulse signal, to a predetermined cam as the main intake camshaft 41 rotates. It outputs to ECU2 for every angle (for example, 1 deg). The ECU 2 calculates (detects) the main intake cam phase θmi based on the main intake cam signal and the CRK signal.
[0048]
On the other hand, the sub intake camshaft 42 is rotatably supported by the cylinder head 3a similarly to the main intake camshaft 41, and extends in parallel with the main intake camshaft 41. The sub intake camshaft 42 has a sub intake cam 44 (second intake cam) provided for each cylinder, and a sub gear 46 having the same number of teeth and the same diameter as the main gear 45. 46 rotates coaxially and integrally with the auxiliary intake camshaft 42.
[0049]
The main gear 45 and the sub gear 46 are both pressed by a pressing spring (not shown) so as to always mesh with each other, and are configured so that backlash is not generated by a backlash compensation mechanism (not shown). Due to the engagement of the gears 45 and 46, the sub intake camshaft 42 rotates counterclockwise in FIG. 6 (in the direction indicated by arrow Y2) at the same rotational speed as the main intake camshaft 41 rotates clockwise. .
[0050]
The auxiliary intake cam phase variable mechanism 70 is provided at the end of the auxiliary intake camshaft 42 on the timing chain 48 side, and the relative phase of the auxiliary intake camshaft 42 with respect to the main intake camshaft 41, in other words, the first The relative phase (hereinafter referred to as “sub intake cam phase”) θmsi of the sub intake cam 44 for the cylinder # 1 with respect to the main intake cam 43 is steplessly changed. Details of the sub intake cam phase variable mechanism 70 will be described later.
[0051]
Further, a sub intake cam angle sensor 28 is provided at an end of the sub intake cam shaft 42 opposite to the variable sub intake cam phase mechanism 70. Similarly to the main intake cam angle sensor 27, the auxiliary intake cam angle sensor 28 is also composed of a magnet rotor and an MRE pickup, and generates a pulse signal of the auxiliary intake cam signal as the auxiliary intake camshaft 42 rotates. Is output to the ECU 2 for each cam angle (for example, 1 deg). The ECU 2 calculates the sub intake cam phase θmsi based on the sub intake cam signal, the main intake cam signal, and the CRK signal.
[0052]
Further, among the four sub intake cams 44, the sub intake cam 44 for the first cylinder # 1 is attached so as to rotate integrally and coaxially with the sub intake cam shaft 42, and the other second to fourth cylinders # 1 to # 4. Each of the sub-intake cams 44 for # 2 to # 4 is connected to the sub-intake camshaft 42 via the inter-intake cam phase variable mechanism 80. The variable phase mechanism between intake cams 80 is used to control the relative phase of the auxiliary intake cams 44 for the second to fourth cylinders # 2 to # 4 with respect to the auxiliary intake cam 44 for the first cylinder # 1 (hereinafter referred to as “intake air”). Θssi # i), which is steplessly changed independently of each other, and will be described in detail later. The symbol #i in the inter-intake cam phase θssi # i represents the cylinder number, and is set to # i = # 2 to # 4. This is the same in the following description.
[0053]
Further, three # 2 to # 4 sub intake cam angle sensors 29 to 31 are electrically connected to the ECU 2 (see FIG. 3). These # 2 to # 4 sub intake cam angle sensors 29 to 31 are pulse signals of # 2 to # 4 sub intake cams 44 for rotation of the sub intake cams 44 for the second to fourth cylinders # 2 to # 4, respectively. An intake cam signal is output to the ECU 2 at every predetermined cam angle (for example, 1 deg). The ECU 2 calculates the inter-intake cam phase θssi # i based on these # 2 to # 4 sub intake cam signals, sub intake cam signals, main intake cam signals, and CRK signals.
[0054]
On the other hand, the intake valve drive mechanism 50 includes main and auxiliary intake cams 43 and 44, an intake rocker arm 51 that opens and closes the intake valve 6, a link mechanism 52 that supports the intake rocker arm 51, and the like. The cam profiles of the main and sub intake cams 43 and 44 will be described later.
[0055]
The link mechanism 52 is of a four-bar link type, and includes a first link 53 extending substantially parallel to the intake valve 6, two second links 54 and 54 provided vertically above and below each other, and a bias spring 55. , A return spring 56 and the like. At the lower end of the first link 53, the center of the intake rocker arm 51 is rotatably attached via a pin 51c, and a rotatable roller 53a is provided at the upper end.
[0056]
The intake rocker arm 51 is provided with a rotatable roller 51a at an end on the main intake cam 43 side, and an adjust bolt 51b is attached on an end on the intake valve 6 side. The valve clearance between the lower edge of the adjustment bolt 51b and the upper edge of the intake valve 6 is set to a predetermined value as described later. The bias spring 55 has one end attached to the intake rocker arm 51 and the other end attached to the first link 53. By the biasing force of the bias spring 55, the intake rocker arm 51 is biased clockwise in FIG. 6, so that it is always in contact with the main intake cam 43 via the roller 51a.
[0057]
With the above configuration, when the main intake cam 43 rotates clockwise in FIG. 6, the intake rocker arm 51 changes the cam profile of the main intake cam 43 by the rollers 51 a rolling on the cam surface of the main intake cam 43. In response, the pin 51c rotates clockwise and counterclockwise about the rotation fulcrum. By the rotation of the intake rocker arm 51, the adjustment bolt bolt 51b reciprocates in the vertical direction, and opens and closes the intake valve 6.
[0058]
One end of each second link 54 is rotatably connected to the cylinder head 3a via a pin 54a, and the other end is rotatably connected to a predetermined portion of the first link 53 via a pin 54b. Are linked. Further, one end of the return spring 56 is attached to the upper second link 54, and the other end is attached to the cylinder head 3a. Due to the urging force of the return spring 56, the upper second link 54 is urged counterclockwise in FIG. 6, whereby the first link 53 is always connected to the sub intake cam 44 via the roller 53a. Abut.
[0059]
With the above configuration, when the sub intake cam 44 rotates counterclockwise in FIG. 6, the first link 53 causes the roller 53 a to roll on the cam surface of the sub intake cam 44, thereby causing the cam of the sub intake cam 44 to rotate. Move up and down according to profile. This causes the pin 51c, which is the pivot point of the intake rocker arm 51, to move vertically between the lowermost position (the position shown in FIG. 6) and the uppermost position (the position shown in FIG. 15). Accordingly, when the intake rocker arm 51 rotates as described above, the position of the reciprocating movement of the adjust bolt bolt 51b changes.
[0060]
The height of the cam ridge of the main intake cam 43 is higher than that of the sub-intake cam 44, and the ratio of the height of the cam ridge between the main intake cam 43 and the sub-intake cam 44 is determined by adjusting the adjustment bolt 51b from the roller. It is set to a value equal to the ratio of the distance from the center of the adjustment bolt 51b to the center of the pin 51c. That is, when the intake rocker arm 51 is driven by the main / sub intake cams 43 and 44, the amount of vertical movement of the adjustment bolt 51 b due to the cam peak of the main intake cam 43 and the adjustment bolt bolt due to the cam peak of the sub intake cam 44. The fluctuation amounts in the vertical direction of 51b are set to be the same as each other.
[0061]
Next, the variable main intake cam phase mechanism 60 will be described. As shown in FIG. 7, the main intake cam phase changing mechanism 60 includes a housing 61, a three-blade vane 62, a hydraulic pump 63, an electromagnetic valve mechanism 64, and the like.
[0062]
The housing 61 is formed integrally with the above-described sprocket 47, and includes three partition walls 61a formed at equal intervals from each other. The vane 62 is coaxially attached to the end of the main intake camshaft 41 on the sprocket 47 side, extends radially outward from the main intake camshaft 41, and is rotatably accommodated in the housing 61. In the housing 61, three advance chambers 65 and three retard chambers 66 are formed between the partition wall 61a and the vane 62.
[0063]
The hydraulic pump 63 is a mechanical pump connected to the crankshaft 3b. When the crankshaft 3b rotates, the oil for lubrication stored in the oil pan 3d of the engine 3 is supplied to the oil passage 67c. The oil is suctioned through the oil passage 67, and is supplied to the electromagnetic valve mechanism 64 via the oil passage 67c in a state where the pressure is increased.
[0064]
The solenoid valve mechanism 64 is a combination of a spool valve mechanism 64a and a solenoid 64b, and is connected to the advance chamber 65 and the retard chamber 66 via an advance oil passage 67a and a retard oil passage 67b, respectively. At the same time, the hydraulic pressure supplied from the hydraulic pump 63 is output to the advance chamber 65 and the retard chamber 66 as the advance hydraulic pressure Pad and the retard hydraulic pressure Prt, respectively. The solenoid 64b of the solenoid valve mechanism 64 is electrically connected to the ECU 2, and when the control input DUTY_mi from the ECU 2 is input, moves the spool valve element of the spool valve mechanism 64a by a predetermined amount according to the control input DUTY_mi. By moving within the range, both the advance hydraulic pressure Pad and the retard hydraulic pressure Prt are changed.
[0065]
In the main intake cam phase variable mechanism 60 described above, during operation of the hydraulic pump 63, the electromagnetic valve mechanism 64 operates in accordance with the control input DUTY_mi, so that the advance hydraulic pressure Pad is supplied to the advance chamber 65, and the retard hydraulic pressure Prt is supplied to the advance chamber 65. Each is supplied to the retard chamber 66, whereby the relative phase between the vane 62 and the housing 64 is changed to the advance side or the retard side. As a result, the aforementioned main intake cam phase θmi is steplessly changed to the advance side or the retard side within a predetermined range (for example, a range of 45 degrees to 60 degrees of cam angle). The main intake cam phase variable mechanism 60 is provided with a lock mechanism (not shown), which locks the operation of the main intake cam phase variable mechanism 60 when the hydraulic pressure supplied from the hydraulic pump 63 is low. Is done. That is, the change of the main intake cam phase θmi by the variable main intake cam phase mechanism 60 is prohibited, and the main intake cam phase θmi is locked to a value suitable for idling or engine start.
[0066]
Next, the sub intake cam phase variable mechanism 70 will be described. As shown in FIG. 8, the auxiliary intake cam phase changing mechanism 70 includes a housing 71, a single vane 72, a hydraulic piston mechanism 73, a motor 74, and the like.
[0067]
The housing 71 is formed integrally with the gear 46 of the sub intake camshaft 42, and has a vane chamber 75 having a fan-shaped cross section formed therein. The vane 72 is coaxially attached to the end of the auxiliary intake camshaft 42 on the timing chain 48 side, extends outward from the auxiliary intake camshaft 42, and is rotatably housed in the vane chamber 75. The vane 72 partitions the vane chamber 75 into first and second vane chambers 75a and 75b.
[0068]
One end of a return spring 72 a is attached to the vane 72, and the other end of the return spring 72 is attached to the housing 71. The return spring 72a urges the vane 72 in a counterclockwise direction in FIG. 8, that is, in a direction to reduce the volume of the first vane chamber 75a.
[0069]
On the other hand, the hydraulic piston mechanism 73 includes a cylinder 73a and a piston 73b. The internal space of the cylinder 73a communicates with the first vane chamber 75a via an oil passage 76, and hydraulic oil is supplied to the internal space of the cylinder 73a, the oil passage 76, and the first vane chamber 75a. Is filled. The second vane chamber 75b communicates with the atmosphere.
[0070]
A rack 77 is attached to the piston 73b, and a pinion 78 that meshes with the rack 77 is attached coaxially to the rotation shaft of the motor 74. The motor 74 is electrically connected to the ECU 2. When a control input DUTY_msi from the ECU 2 is input, the motor 74 drives the pinion 78 to rotate, so that the piston 73 b slides in the cylinder 73 a via the rack 77. Let it. Accordingly, the oil pressure Psd in the first vane chamber 75a changes, and the vane 72 rotates clockwise or counterclockwise due to the balance between the oil pressure Psd thus changed and the urging force of the return spring 72a. As a result, the sub intake cam phase θmsi is continuously changed to the advance side or the retard side within a predetermined range (a range of a cam angle of 180 deg described later).
[0071]
As described above, in the sub intake cam phase variable mechanism 70, the hydraulic piston mechanism 73 and the motor 74 are used instead of the hydraulic pump 63 and the solenoid valve mechanism 64 of the main intake cam phase variable mechanism 60 described above, so that The intake cam phase θmsi is changed. This is because the sub intake cam phase variable mechanism 70 is used for adjusting the amount of intake air to each cylinder, and therefore requires higher responsiveness than the main intake cam phase variable mechanism 60. Therefore, when high responsiveness is not required in the variable sub-intake cam phase mechanism 70 (for example, when only one of the late closing control and the early closing control needs to be executed in the valve timing control of the intake valve 6 described later). Instead of the hydraulic piston mechanism 73 and the motor 74, a hydraulic pump 63 and an electromagnetic valve mechanism 64 may be used as in the main intake cam phase variable mechanism 60.
[0072]
As shown in FIG. 9, a return spring 72b for urging the vane 72 in the clockwise direction in FIG. 9 is provided in the variable sub-intake cam phase mechanism 70, and the urging force of the return spring 72b is used as the return spring 72a. In addition to setting the same value, the neutral position of the vane 72 shown in the figure may be set to a position corresponding to a value at which the sub intake cam phase θmsi is most frequently controlled. With this configuration, during operation of the variable sub-intake cam phase mechanism 70, the time during which the vane 72 is held at the neutral position becomes longer, so that a longer operation stop time of the motor 74 can be ensured, thereby reducing power consumption. Can be reduced.
[0073]
Next, the above-described phase variable mechanism between intake cams 80 will be described. Since the three inter-intake cam phase variable mechanisms 80 have the same configuration, the inter-intake cam phase for changing the inter-intake cam phase θssi # 2 of the sub intake cam 44 for the second cylinder # 2 will be described below. A description will be given taking the variable mechanism 80 as an example. The inter-intake cam phase variable mechanism 80 is for adjusting the steady variation of the intake air amount among the cylinders, and does not require high responsiveness. The configuration is the same as that of 60 except for a part. That is, as shown in FIG. 10, the intake cam phase variable mechanism 80 includes a housing 81, a vane 82, a hydraulic pump 83, an electromagnetic valve mechanism 84, and the like.
[0074]
The housing 81 is integrally formed with the sub intake cam 44 for the second cylinder # 2, and has one partition 81a. The vane 82 is mounted coaxially in the middle of the auxiliary intake camshaft 42 and is rotatably accommodated in the housing 81. Further, in the housing 81, an advance chamber 85 and a retard chamber 86 are formed between the partition wall 81a and the vane 82.
[0075]
The hydraulic pump 83 is a mechanical pump connected to the crankshaft 3b, similarly to the hydraulic pump 63 described above. When the crankshaft 3b rotates, the lubrication stored in the oil pan 3d of the engine 3 is generated. Oil is sucked in through the oil passage 87c and is supplied to the electromagnetic valve mechanism 84 through the oil passage 87c in a state where the oil is pressurized.
[0076]
The electromagnetic valve mechanism 84 is a combination of the spool valve mechanism 84a and the solenoid 84b, similarly to the above-described electromagnetic valve mechanism 64, and is provided with the advance chamber 85 and the advance chamber 85 via the advance oil passage 87a and the retard oil passage 87b. The hydraulic pressure supplied from the hydraulic pump 83 and connected to the retard chamber 86 is output to the advance chamber 85 and the retard chamber 86 as an advance hydraulic pressure Pad and a retard hydraulic pressure Prt, respectively. The solenoid 84b of the solenoid valve mechanism 84 is electrically connected to the ECU 2, and when a control input DUTY_ssi # 2 is input from the ECU 2, the solenoid valve 84 changes the spool valve body of the spool valve mechanism 84a according to the control input DUTY_ssi # 2. Thus, both the advance hydraulic pressure Pad and the retard hydraulic pressure Prt are changed by moving within the predetermined movement range.
[0077]
In the above-described phase variable mechanism between intake cams 80, during operation of the hydraulic pump 83, the electromagnetic valve mechanism 84 operates according to the control input DUTY_ssi # 2, so that the advance hydraulic pressure Pad is transferred to the advance chamber 85 and the retard hydraulic pressure Prt is supplied to each of the retard chambers 86, whereby the relative phase between the vane 82 and the housing 84 is changed to the advance side or the retard side. As a result, the above-described intake cam phase θssi # 2 is steplessly changed to the advance side or the retard side within a predetermined range (for example, a range of a cam angle of 30 deg). The inter-intake cam phase variable mechanism 80 is provided with a lock mechanism (not shown), which locks the operation of the inter-intake cam phase variable mechanism 80 when the hydraulic pressure supplied from the hydraulic pump 83 is low. Is done. That is, the change of the inter-intake cam phase θssi # 2 by the inter-intake cam phase variable mechanism 80 is prohibited, and the inter-intake cam phase θssi # 2 is locked to the control target value (value 0 described later) at that time.
[0078]
When it is necessary to control the internal EGR amount and the intake air amount of each cylinder with high responsiveness and high accuracy as in the case of a compression ignition type internal combustion engine, the intake cam phase variable The configuration may be similar to that of the variable intake cam phase mechanism 70.
[0079]
Next, the operation of the variable intake valve driving device 40 configured as described above will be described. In the following description, the main / sub intake cams 43 and 44 will be described as an example for the first cylinder # 1. FIG. 11 is a view for explaining the cam profiles of the main and sub intake cams 43 and 44. The operation state when the sub intake cam phase variable mechanism 70 sets the sub intake cam phase θmsi = 0deg, that is, An operation state when there is no phase difference between the sub intake cam 44 and the main intake cam 43 is shown.
[0080]
A curve shown by a one-dot chain line in the figure indicates a contact point between the main intake cam 43 and the intake rocker arm 51 when the main intake cam 43 rotates, that is, a variation amount of the roller 51a and its variation timing. The curve shown by represents the amount of fluctuation of the first link 53, that is, the pin 51c, when the sub intake cam 44 rotates, and the fluctuation timing thereof. This is the same in FIGS. 12 to 16 below.
[0081]
Further, a curve shown by a two-dot chain line in FIG. 11 shows, for comparison, an intake cam (hereinafter, referred to as an engine) of a general engine operated in an Otto cycle, that is, an engine operated so that the expansion ratio and the compression ratio are the same. This indicates the amount and timing of the change of the adjustment bolt 51b due to “Otto intake cam”. Since a curve obtained by adding the valve clearance to this curve corresponds to a valve lift curve of the intake valve by the Otto intake cam, this curve is appropriately referred to as a valve lift curve in the following description.
[0082]
As shown in the drawing, the main intake cam 43 has the same lift start timing, that is, the valve opening timing, and the lift end timing, that is, the valve closing timing, is a later timing of the compression stroke than the Otto intake cam. It is configured as a closed cam, and has a cam profile in which the maximum valve lift is maintained in a predetermined range (for example, a cam angle of 150 deg). In the following description, a state in which the intake valve 6 is closed at a timing later and earlier than the Otto intake cam is referred to as “slowly closed” or “early closed” of the intake valve 6, respectively.
[0083]
Further, the auxiliary intake cam 44 has a cam profile in which the valve opening timing is earlier than the main intake cam 43 and the state in which the maximum valve lift amount is maintained in the above-mentioned predetermined range (for example, a cam angle of 150 deg). are doing.
[0084]
The operation when the intake valve 6 is actually driven by the main / sub intake cams 43 and 44 having the above-described cam profiles will be described with reference to FIGS. FIG. 12 shows an operation example when the sub intake cam phase θmsi = 0 deg. The curve shown by the solid line in FIG. 6B shows the actual variation amount and the variation timing of the adjustment bolt 51b. As described above, the value obtained by taking the valve clearance into account is the intake valve 6b. Corresponds to a valve lift curve indicating the actual valve lift amount and valve timing. Therefore, in the following description, this curve is appropriately referred to as a valve lift curve of the intake valve 6, and the fluctuation amount of the adjustment bolt 51 b and its fluctuation timing are referred to as a valve lift amount and valve timing of the intake valve 6. This is the same in FIGS. 13B to 16B.
[0085]
As shown in FIG. 12A, when the sub intake cam phase θmsi = 0deg, during the period when the main intake cam 43 is in contact with the intake rocker arm 51 at a position where the cam ridge is high, the sub intake cam 44 is The first link 53 comes into contact with the high portion of the mountain. That is, during the valve opening operation by the main intake cam 43, the pivot of the intake rocker arm 51 is held at the lowest position. As a result, as shown in FIG. 12 (b), the valve lift amount and valve timing of the intake valve 6 have the same valve opening timing and later valve closing timing as compared to the Otto intake cam, and the late closing cam The intake valve 6 is being driven.
[0086]
FIGS. 13 to 15 show operation examples when the auxiliary intake cam phase θmsi is set to 90 deg, 120 deg, and 180 deg by the auxiliary intake cam phase variable mechanism 70, respectively. In other words, an operation example in which the phase of the sub intake camshaft 42 is shifted to the advance angle side by 90 degrees, 120 degrees, and 180 degrees of the cam angles with respect to the main intake camshaft 41 is shown. FIG. 16 shows an operation example when the sub intake cam phase θmsi is changed from 120 deg to 180 deg.
[0087]
As shown in FIG. 13A, when θmsi = 90 deg (a value equal to θmsiott, which will be described later), in the latter half of the period when the main intake cam 43 is in contact with the intake rocker arm 51 at a portion where the cam ridge is high, The sub-intake cam 44 comes into contact with the first link 53 not at a high portion of the cam peak but at a low portion. As a result, as shown in FIG. 3B, the closing timing of the intake valve 6 is earlier than when θmsi = 0 deg, and has the same valve timing as the Otto intake cam described above.
[0088]
When θmsi is larger than 90 deg, for example, when θmsi = 120 deg shown in FIG. 14A, the sub intake cam 44 is in contact with the intake rocker arm 51 at a position where the main intake cam 43 has a high cam ridge. The contact time of the first link 53 at the high point of the cam peak is shorter than when θmsi = 90 deg. As a result, as shown in FIG. 3B, the closing timing of the intake valve 6 is further earlier than when the above-mentioned θmsi = 90 deg, and the valve opening timing is the same as that of the Otto intake cam and the valve closing timing is the same. The timing becomes earlier, and the intake valve 6 is driven by the early closing cam.
[0089]
Further, as shown in FIG. 16, when the auxiliary intake cam phase θmsi is changed from the above 120 deg to 180 deg, the auxiliary intake cam 43 is in contact with the intake rocker arm 51 at a position where the peak of the main intake cam 43 is high. The time during which the 44 abuts on the first link 53 at a high portion of the cam peak gradually decreases, as a result, the closing timing of the intake valve 6 gradually advances, and the valve lift of the intake valve 6 gradually decreases from its maximum value. . As described above, when the auxiliary intake cam phase θmsi is set by the variable auxiliary intake cam phase mechanism 70 so that the valve lift amount of the intake valve 6 becomes smaller than the maximum value, the flow velocity of the intake air flowing into the combustion chamber is increased. And the in-cylinder flow can be further increased. Thereby, the combustion efficiency can be improved.
[0090]
Finally, when θmsi = 180 deg, as shown in FIG. 15A, during the period when the main intake cam 43 is in contact with the intake rocker arm 51 at a position where the cam ridge is high, the auxiliary intake cam 43 Reference numeral 44 denotes a state in which the lower part of the cam peak comes into contact with the first link 53. As a result, as shown in FIG. Is slightly smaller than the valve clearance. As a result, when θmsi = 180 deg, the intake valve 6 is not driven by the adjustment bolt 51b, so that the intake valve 6 is kept closed.
[0091]
In the variable intake valve driving device 40 described above, the valve lift curve of the intake valve 6 is the same as that of the Otto intake cam when the auxiliary intake cam phase θmsi = 90 deg. The value of the sub intake cam phase θmsi at which the valve lift curve of the valve 6 becomes the same as the Otto intake cam can be changed as appropriate by changing the cam profiles of the main and sub intake cams 43 and 44.
[0092]
Next, the variable exhaust valve driving device 90 will be described. The variable exhaust valve driving device 90 has substantially the same configuration as the above-described variable intake valve driving device 40, and includes a main exhaust cam shaft 91 and a sub exhaust cam shaft 92 for driving an exhaust valve, and a An exhaust valve driving mechanism 100 (only one is shown in FIG. 2) that opens and closes the exhaust valve 7 with the rotation of the main and sub exhaust camshafts 91 and 92; A variable sub-exhaust cam phase mechanism 120 and three variable phase inter-exhaust cam mechanisms 130 are provided.
[0093]
The main exhaust camshaft 91 includes a main exhaust cam 93 provided for each cylinder, a main gear 95 attached integrally, and a sprocket 97 provided at one end. The sprocket 97 is connected to the crankshaft 3b via the above-described timing chain 48, similarly to the sprocket 47 of the main exhaust camshaft 41. Thus, the main exhaust camshaft 91 makes one rotation every two rotations of the crankshaft 3b.
[0094]
The main exhaust cam phase variable mechanism 110 controls the relative phase of the main exhaust camshaft 91 with respect to the sprocket 97, that is, the relative phase of the main exhaust camshaft 91 with respect to the crankshaft 3b (hereinafter referred to as “main exhaust cam phase”). θme is steplessly changed to the advance side or the retard side. The variable main exhaust cam phase mechanism 110 is specifically configured in the same manner as the main intake cam phase variable mechanism 60 described above, and a description thereof will be omitted here.
[0095]
Further, a main exhaust cam angle sensor 32 is provided at an end of the main exhaust camshaft 91 opposite to the sprocket 97. The main exhaust cam angle sensor 32, like the main intake cam angle sensor 27, is composed of a magnet rotor and an MRE pickup, and generates a pulse signal of the main exhaust cam signal as the main exhaust cam shaft 91 rotates. Is output to the ECU 2 for each cam angle (for example, 1 deg). The ECU 2 calculates the main exhaust cam phase θme based on the main exhaust cam signal and the CRK signal.
[0096]
On the other hand, the sub exhaust camshaft 92 has a sub exhaust cam 94 provided for each cylinder, and a sub gear 96 having the same number of teeth as the main gear 95. Like the main and sub gears 45 and 46, the main and sub gears 95 and 96 are pressed by a pressing spring (not shown) so as to always mesh with each other. It is configured so that rush does not occur. The meshing of the gears 95 and 96 causes the auxiliary exhaust camshaft 92 to rotate in the opposite direction at the same rotational speed as the main exhaust camshaft 91 rotates.
[0097]
In addition, the auxiliary exhaust cam phase variable mechanism 120 controls the relative phase of the auxiliary exhaust camshaft 92 with respect to the gear 96, that is, the relative phase of the auxiliary exhaust camshaft 92 with respect to the main exhaust camshaft 91 (hereinafter referred to as “auxiliary exhaust cam phase”). ) It changes θmse steplessly. The variable sub-exhaust cam phase mechanism 120 is specifically configured in the same manner as the variable sub-intake cam phase mechanism 70 described above, and a description thereof will be omitted.
[0098]
On the other hand, a sub exhaust cam angle sensor 33 is provided at an end of the sub exhaust cam shaft 92 opposite to the sub exhaust cam phase variable mechanism 120. Like the main exhaust cam angle sensor 32, the sub-exhaust cam angle sensor 33 includes a magnet rotor and an MRE pickup. Is output to the ECU 2 for each cam angle (for example, 1 deg). The ECU 2 calculates the sub exhaust cam phase θmse based on the sub exhaust cam signal, the main exhaust cam signal, and the CRK signal.
[0099]
Further, the sub-exhaust cam 94 for the first cylinder # 1 is mounted so as to rotate coaxially and integrally with the sub-exhaust camshaft 92, and is used for the other second to fourth cylinders # 2 to # 4. Each of the sub exhaust cams 94 is connected to the sub exhaust cam shaft 92 via the inter-exhaust cam phase changing mechanism 130. The variable phase mechanism 130 between the exhaust cams is used to control the relative phase of the sub exhaust cams 94 for the second to fourth cylinders # 2 to # 4 with respect to the sub exhaust cam 94 for the first cylinder # 1 (hereinafter referred to as “exhaust”). Θmse # 2 to # 4 are independently and steplessly changed independently of each other. Specifically, since it is configured in the same manner as the intake cam phase variable mechanism 80 described above, The description is omitted here.
[0100]
On the other hand, the exhaust valve drive mechanism 100 has the same configuration as the intake valve drive mechanism 50, and includes main and auxiliary exhaust cams 93 and 94, an exhaust rocker arm 101 that opens and closes the exhaust valve 7, and a link that supports the exhaust rocker arm 101. It is composed of a mechanism 102 and the like. The main / sub exhaust cams 93, 94 have the same cam profile as the main / sub intake cams 43, 44, respectively. Further, the exhaust rocker arm 101 and the link mechanism 102 are configured in the same manner as the intake rocker arm 51 and the link mechanism 52 described above, respectively. An adjusting bolt 101b similar to the adjusting bolt 51b described above is attached to the end of the adjusting bolt 101b. Further, the exhaust rocker arm 101 is rotatably supported by the first link 103.
[0101]
Next, the operation of the variable exhaust valve driving device 90 configured as described above will be described. In the following description, the main / sub exhaust cams 93 and 94 will be described as an example for the first cylinder # 1. FIG. 17 is a view for explaining the cam profiles of the main and sub exhaust cams 93 and 94, and shows an operation example when the sub exhaust cam phase θmse = 0 deg is set by the sub exhaust cam phase variable mechanism 120. ing.
[0102]
The curve shown by the one-dot chain line in the figure represents the amount and timing of the change of the contact point between the main exhaust cam 93 and the exhaust rocker arm 101 when the main exhaust cam 93 rotates, and the curve shown by the broken line in the figure is , The amount of fluctuation of the first link 103 when the auxiliary exhaust cam 94 rotates and the fluctuation timing thereof. This is the same in FIGS. 18 to 21 described below.
[0103]
Further, a curve shown by a two-dot chain line in FIG. 5 shows, for comparison, the fluctuation amount of the adjustment bolt 101b due to the exhaust cam of a general engine operated in the Otto cycle (hereinafter referred to as “Otto exhaust cam”) and the fluctuation thereof. It shows the timing. A curve obtained by adding the valve clearance to this curve corresponds to a valve lift curve of the exhaust valve by the Otto exhaust cam, and this curve is appropriately referred to as a valve lift curve in the following description.
[0104]
As shown in the drawing, the main exhaust cam 93 is configured as a so-called early opening cam, which has the same valve closing timing as the Otto exhaust cam and the valve opening timing is opened earlier in the expansion stroke. And a cam profile in which a state in which the maximum valve lift amount is maintained in a predetermined range (for example, a cam angle of 90 degrees).
[0105]
Further, the auxiliary exhaust cam 94 has a cam profile in which the valve opening time is longer than that of the main exhaust cam 93 and the state in which the maximum valve lift amount is maintained in a longer predetermined range (for example, a cam angle of 150 deg). are doing.
[0106]
The operation when the exhaust valve 7 is actually driven by the main / sub exhaust cams 93 and 94 having the above-described cam profiles will be described with reference to FIGS. FIG. 18 shows an operation example when the sub exhaust cam phase θmse = 0 deg. It should be noted that the curve shown by the solid line in the figure shows the actual fluctuation amount of the adjustment bolt 101b and its fluctuation timing, and substantially corresponds to the valve lift curve of the exhaust valve 7 as described above. . Therefore, in the following description, this curve is appropriately referred to as a valve lift curve of the exhaust valve 7, and the actual fluctuation amount of the adjustment bolt 101b and its fluctuation timing are referred to as the valve lift amount and valve timing of the exhaust valve 7. This is the same in FIGS.
[0107]
As described above, the case where the sub exhaust cam phase θmse = 0 deg corresponds to the case where the main intake cam phase θmsi = 180 deg. Therefore, the period in which the main exhaust cam 93 is in contact with the exhaust rocker arm 101 at a high portion of the cam peak. In the middle, the sub exhaust cam 94 comes into contact with the first link 103 at a lower portion of the cam peak. As a result, as shown in FIG. 18, the fluctuation amount of the adjustment bolt 101b is extremely small, and the maximum value is slightly smaller than the valve clearance. Therefore, when θmse = 0 deg, the exhaust valve 7 is not driven by the adjustment bolt 101b, so that the exhaust valve 7 is maintained in the closed state.
[0108]
FIGS. 19 to 21 show operation examples when the sub exhaust cam phase θmse is set to 45 deg, 90 deg, and 150 deg by the sub exhaust cam phase variable mechanism 120, respectively. In other words, an operation example in which the phase of the sub exhaust camshaft 92 is shifted to the advance angle side by 45 degrees, 90 degrees, and 150 degrees with respect to the main exhaust camshaft 91 with respect to the main exhaust camshaft 91 is shown.
[0109]
With the configuration of the exhaust valve driving mechanism 100 described above, as θmse increases, that is, as the phase of the sub exhaust camshaft 92 is advanced with respect to the main exhaust camshaft 91, the main exhaust cam 93 becomes higher in the portion where the cam peak is higher. During the period in which the auxiliary exhaust cam 94 is in contact with the exhaust rocker arm 101, the time during which the sub exhaust cam 94 contacts the first link 103 at a portion where the cam peak is high becomes longer. As a result, as shown in FIGS. 19 to 21, as θmse increases, the valve opening timing of the exhaust valve 7 becomes earlier.
[0110]
Specifically, when θmse = 45 deg shown in FIG. 19, the valve closing timing is the same and the valve opening timing is later than that of the Otto exhaust cam, and the exhaust valve 7 is driven by the slow opening cam. It becomes. When θmse = 90 deg shown in FIG. 20, the valve timing of the exhaust valve 7 is the same as the valve timing of the Otto exhaust cam. Further, when θmse is larger than 90 deg, for example, when θmse = 150 deg shown in FIG. The valve 7 is driven. Although not shown, in the range of θmse = 0 to 60 deg, the valve lift of the exhaust valve 7 is configured to increase as θmse increases.
[0111]
On the other hand, as shown in FIG. 3, the ECU 2 is connected to an intake pipe temperature sensor 34, an accelerator opening sensor 35 (load detecting means), and an ignition switch (hereinafter referred to as "IG-SW") 36. The temperature sensor 34 in the intake pipe outputs a detection signal indicating the air temperature TB in the intake pipe 8 to the ECU 2, and the accelerator opening sensor 35 outputs a depression amount of an accelerator pedal (not shown) of the vehicle (hereinafter referred to as "accelerator opening"). ) Output a detection signal indicating the AP to the ECU 2. Further, the IG / SW 36 is turned on / off by operating an ignition key (not shown), and outputs a signal representing the ON / OFF state to the ECU 2.
[0112]
Next, the ECU 2 will be described. The ECU 2 includes a microcomputer including an I / O interface, a CPU, a RAM, a ROM, and the like. The ECU 2 responds to the detection signals of the various sensors 20 to 35 and the output signal of the IG / SW 36 to control the engine 3. In addition to discriminating the operating state, various control processes to be described later are executed in accordance with a control program stored in the ROM or data stored in the RAM. In the present embodiment, the ECU 2 constitutes a load detecting unit, a valve closing timing determining unit, and a control unit.
[0113]
As shown in FIG. 22, the control device 1 includes a DUTY_th calculation unit 200, a Gcyl calculation unit 210, a sub-intake cam phase controller 220, and an intake cam phase controller 230. It consists of. In the DUTY_th calculation unit 200, a target opening TH_cmd, which is a target value of the throttle valve opening TH, is calculated according to a target intake air amount Gcyl_cmd, and further according to the target opening TH_cmd, as described later. The control input DUTY_th to the throttle valve mechanism 16 is calculated.
[0114]
The Gcyl calculation unit 210 calculates the cylinder intake air amount Gcyl estimated to have been taken into the cylinder by the equation (1) shown in FIG. In this equation (1), VB represents an intake pipe volume, and R represents a predetermined gas constant. The symbol n represents the discretized time, and each discrete data (time-series data) with the symbols (n), (n-1), etc. has a predetermined period (for example, input synchronization or a constant value of a TDC signal). Indicates that the data is sampled by. The data with the symbol (n) indicates the current value, and the data with the symbol (n-1) indicates the previous value. This applies to other discrete data in the following description. Further, in the description in this specification, symbols (n), (n-1) and the like representing discrete data are appropriately omitted.
[0115]
The sub intake cam phase controller 220 calculates a control input DUTY_msi to the sub intake cam phase variable mechanism 70 in accordance with the cylinder intake air amount Gcyl calculated by the Gcyl calculation unit 210 and the like. Will be described later.
[0116]
Further, the intake cam phase controller 230 is for correcting variations in the intake air amount between the cylinders, and a detailed description thereof is omitted here. The phase θssi # i_cmd (# i = # 2 to # 4) is calculated, and the control inputs DUTY_ssi # 2 to # 4 are calculated accordingly. By outputting these control inputs DUTY_ssi # 2 to # 4 to the three intake cam phase variable mechanisms 80, respectively, the phase between the intake cams of the second to fourth cylinders # 2 to # 4 with respect to the first cylinder # 1 is output. θssi # 2 to # 4 are controlled.
[0117]
Next, the auxiliary intake cam phase controller 220 will be described. As shown in FIG. 23, the auxiliary intake cam phase controller 220 includes a first SPAS controller 221 (valve closing timing determining means) for calculating a target auxiliary intake cam phase θmsi_cmd. , A second SPAS controller 225 for calculating the control input DUTY_msi.
[0118]
The first SPAS controller 221 uses the adaptive prediction type response assignment control algorithm (Self-tuning Prediction Control Assignment) algorithm described below to perform cylinder suction based on the cylinder intake air amount Gcyl, the target intake air amount Gcyl_cmd, and the required drive torque TRQ_eng. The target sub intake cam phase θmsi_cmd is calculated such that the air amount Gcyl converges to the target intake air amount Gcyl_cmd and the sub intake cam phase θmsi is restricted to a basic value θmsi_base described later. It comprises an on-board identifier 223 and a sliding mode controller 224.
[0119]
First, the state predictor 222 will be described. The state predictor 222 predicts (calculates) a predicted intake air amount Pre_Gcyl which is a predicted value of the cylinder intake air amount Gcyl by a prediction algorithm described below.
[0120]
First, a control object having a cylinder intake air amount Gcyl and a sub intake cam phase θ msi as an input and an output, respectively, is an ARX model (auto-regressive model with exogenous input: an autoregressive model having an external input) which is a discrete time system model. By modeling, the equation (2) shown in FIG. 24 is obtained. In the equation (2), d represents a dead time determined by the characteristics of the control target. Also, a1, a2, and b1 represent model parameters, and are sequentially identified by the on-board identifier 223 as described later.
[0121]
Next, when the equation (2) is shifted to the future side by the discrete time [d-1], the equation (3) in FIG. 24 is obtained. Further, the matrices A and B are defined using the model parameters a1, a2, and b1 as shown in equations (4) and (5) shown in FIG. 24, and the future value [Gcyl ( n + d-2), Gcyl (n + d-3)], the equation (3) is transformed by repeatedly using the recurrence equation of the above equation (3), and the equation (6) shown in FIG. 24 is obtained. Can be
[0122]
Although it is possible to calculate the predicted intake air amount Pre_Gcyl by using the equation (6), the steady-state error and the predicted intake air amount Pre_Gcyl are caused by the shortage of the model order and the nonlinear characteristic of the control target. Modeling errors can occur.
[0123]
In order to avoid this, the state predictor 222 of the present embodiment calculates the predicted intake air amount Pre_Gcyl by using Expression (7) shown in FIG. 24 instead of Expression (6). This equation (7) is obtained by adding a compensation parameter γ1 for compensating for the steady-state error and the modeling error to the right side of the equation (6).
[0124]
Next, the on-board identifier 223 will be described. The on-board identifier 223 uses an iterative identification algorithm described below so that the identification error ide, which is the deviation between the predicted intake air amount Pre_Gcyl and the cylinder intake air amount Gcyl, is minimized (that is, the predicted intake air amount). In order to make the amount Pre_Gcyl coincide with the cylinder intake air amount Gcyl), the matrix components α1, α2, βj of the model parameters and the vector θs of the compensation parameter γ1 in equation (7) are identified.
[0125]
Specifically, the vector θs (n) is calculated by the equations (8) to (13) shown in FIG. The transpose of the vector θs (n) is defined as shown in equation (12) of FIG. In equation (8), KPs (n) represents a vector of a gain coefficient, and this gain coefficient KPs (n) is calculated by equation (9). In Expression (9), Ps (n) is a d + 2 square matrix defined by Expression (10), and ζs (n) is a vector whose transposed matrix is defined as Expression (13). is there. Further, the identification error ide (n) in Expression (8) is calculated by Expression (11).
[0126]
In the above-described identification algorithm, one of the following four identification algorithms is selected by setting the weight parameters λ1 and λ2 in Expression (10).
That is,
λ1 = 1, λ2 = 0; fixed gain algorithm
λ1 = 1, λ2 = 1; Least squares algorithm
λ1 = 1, λ2 = λ; decreasing gain algorithm
λ1 = λ, λ2 = 1; weighted least squares algorithm
Here, λ is a predetermined value set to 0 <λ <1.
In the present embodiment, a weighted least squares algorithm is employed in order to optimally secure both the identification accuracy and the convergence speed of the vector θs to the optimum value.
[0127]
Next, the sliding mode controller (hereinafter, referred to as “SLD controller”) 224 will be described. The SLD controller 224 operates based on the sliding mode control algorithm so that the cylinder intake air amount Gcyl converges to the target intake air amount Gcyl_cmd and the sub intake cam phase θmsi is restricted to the basic value θmsi_base. The phase θ msi_cmd is calculated. Hereinafter, the sliding mode control algorithm will be described.
[0128]
First, in this sliding mode control algorithm, Expression (14) shown in FIG. 26 is used as a control target model. This equation (14) is obtained by shifting equation (6) of FIG. 24 described above to the future side by the discrete time “1”.
[0129]
When the control target model shown in Expression (14) is used, the switching function σs is set as follows. That is, if the following error Es is defined as a deviation between the cylinder intake air amount Gcyl and the target intake air amount Gcyl_cmd as shown in the equation (15) in FIG. 26, the switching function σs is as shown in the equation (16) in FIG. Is set as a linear function of the time series data (discrete data) of the tracking error Es. Note that Ss shown in Expression (16) represents a switching function setting parameter.
[0130]
In the sliding mode control algorithm, when the switching function s is composed of two state variables [Es (n) and Es (n-1)] as in the present embodiment, as shown in FIG. The phase space composed of variables is a two-dimensional phase plane having these as the vertical axis and the horizontal axis. On this phase plane, the combination of the values of the two state variables satisfying σs = 0 is expressed by the formula [Es (N) = − Ss · Es (n−1)] on a straight line called a switching straight line.
[0131]
Since this equation [Es (n) = − Ss · Es (n−1)] represents a first-order lag system with no input, the switching function setting parameter Ss is set to, for example, −1 <Ss <1, and When this first-order lag system is stabilized, the combination of the two state variables [Es (n), Es (n-1)] converges to an equilibrium point where the value becomes 0 with the passage of time. That is, by causing the tracking error Es to converge to the value 0, the cylinder intake air amount Gcyl can converge to the target intake air amount Gcyl_cmd. Note that a period until the two state variables [Es (n), Es (n-1)] asymptotically approaches the switching straight line is called a reaching mode, and a behavior in which they slide to an equilibrium point is called a sliding mode.
[0132]
In this case, if the switching function setting parameter Ss is set to a positive value, the first-order lag system represented by the equation [Es (n) =-Ss · Es (n-1)] becomes a vibration stable system. This is not preferable as the convergence behavior of [Es (n), Es (n-1)]. Therefore, in the present embodiment, the switching function setting parameter Ss is set as shown in Expression (17) of FIG. When the switching function setting parameter Ss is set in this manner, as shown in FIG. 29, as the absolute value of the switching function setting parameter Ss becomes smaller, the convergence speed of the following error Es to the value 0, that is, the cylinder intake air amount Gcyl becomes smaller. The convergence speed to the target intake air amount Gcyl_cmd increases. As described above, in the sliding mode control, the convergence behavior and the convergence speed of the cylinder intake air amount Gcyl to the target intake air amount Gcyl_cmd can be arbitrarily specified by the switching function setting parameter Ss.
[0133]
The control input Uspas (n) [= θmsi_cmd (n)] for placing a combination of these state variables [Es (n), Es (n−1)] on the switching line is represented by the equation (18) in FIG. ), It is defined as the sum of the equivalent control input Ueq (n), the reaching law input Urch (n), and the valve control input Uvt (n).
[0134]
This equivalent control input Ueq (n) is for keeping the combination of [Es (n), Es (n-1)] on the switching line, and specifically, the equation shown in FIG. It is defined as (19). This equation (19) is derived as follows. That is, when the equation (22) shown in FIG. 27 is modified based on the above-mentioned equation (16), the equation (23) shown in FIG. 27 is obtained. When it is deformed by using, equation (24) shown in FIG. 27 is obtained. Further, when the term of the sub intake cam phase θmsi in the equation (24) is collectively deformed, the equation (25) shown in FIG. 27 is obtained. Next, in the equation (25), the sub intake cam phase θmsi (n) on the left side is replaced with the equivalent control input Ueq (n), and at the same time, based on the relationship of Pre_Gcyl (n) ≒ Gcyl (n + d−1), The above expression (19) is derived by replacing the future value Gcyl (n + d-1) of the cylinder intake air amount on the right side with the predicted value Pre_Gcyl.
[0135]
In addition, when the combination of [Es (n), Es (n-1)] deviates from the switching straight line due to disturbance, modeling error, or the like, the reaching law input Urch (n) places these on the switching straight line. This is for convergence, and is specifically defined as Expression (20) shown in FIG.
[0136]
Further, the valve control input Uvt (n) is a feedforward input for restricting the sub intake cam phase θmsi to its basic value θmsi_base. Specifically, as shown in the equation (21) in FIG. It is defined as a value equal to the value θmsi_base. Note that this basic value θmsi_base is calculated according to the required drive torque TRQ_eng (a parameter representing the load), as described later.
[0137]
As described above, in the first SPAS controller 221, in the state predictor 222, the predicted intake air amount Pre_Gcyl is calculated by the state prediction algorithm to which the compensation parameter γ1 is added, and the compensation parameter γ1 is calculated by the on-board identifier 223. Thus, the predicted intake air amount Pre_Gcyl can be calculated with high accuracy while compensating for the above-described steady-state deviation and modeling error.
[0138]
Further, in the SLD controller 224, the following error Es can be made to converge to the value 0 by the reaching law input Urch and the equivalent control input Ueq. That is, the cylinder intake air amount Gcyl can be made to converge to the target intake air amount Gcyl_cmd, and at the same time, the convergence behavior and the convergence speed can be arbitrarily specified by setting the switching function setting parameter Ss. Therefore, the convergence speed of the cylinder intake air amount Gcyl to the target intake air amount Gcyl_cmd can be set to an appropriate value according to the characteristics of the control target (the intake system including the sub intake cam phase variable mechanism 70 and the like). Thereby, controllability can be improved.
[0139]
In addition to this, the auxiliary intake cam phase θmsi can be restricted to its basic value θmsi_base by the valve control input Uvt, and at the same time, the compensation control parameter γ1 is included in the equivalent control input Ueq. The cylinder intake air amount Gcyl can be appropriately converged to the target intake air amount Gcyl_cmd while compensating for the influence of Uvt.
[0140]
Next, the second SPAS controller 225 will be described. The second SPAS controller 225 calculates the control input DUTY_msi in accordance with the sub intake cam phase θmsi and the target sub intake cam phase θmsi_cmd by a control algorithm similar to that of the first SPAS controller 221 except for a part. As shown in FIG. 30, it comprises a state predictor 226, an on-board identifier 227, and a sliding mode controller 228.
[0141]
The state predictor 226 predicts (calculates) a predicted auxiliary intake cam phase Pre_θmsi which is a predicted value of the auxiliary intake cam phase θmsi using the same prediction algorithm as the state predictor 222 described above.
[0142]
Specifically, equation (26) shown in FIG. 31 is used as the control target model. In the equation (26), dx represents a dead time determined by the characteristics of the control target, and a1 ', a2', and b1 'represent model parameters. In addition, the symbol m represents the discretized time, and indicates that each discrete data with the symbol (m) is data sampled at a predetermined cycle shorter than the discrete data with the symbol (n) described above. ing. The same applies to other discrete data in the following description of the present specification, and in the description of the present specification, the symbol (m) indicating that the data is the discrete data is appropriately omitted. As described above, the reason why the sampling cycle of each discrete data in the equation (26) is set to be shorter than the cycle of each discrete data in the aforementioned equation (2) is that the second SPAS controller 225 uses If the convergence speed of the cam phase θmsi to the target auxiliary intake cam phase θmsi_cmd is slower than the convergence speed of the cylinder intake air amount Gcyl to the target intake air amount Gcyl_cmd by the first SPAS controller 221, controllability is reduced. This is to avoid this and ensure good controllability.
[0143]
The matrices A ′ and B ′ are defined using the model parameters a1 ′, a2 ′ and b1 ′ as shown in equations (27) and (28) shown in FIG. By performing the deformation in the same manner as in the case of 222, Expression (29) shown in FIG. 31 is derived. In this equation (29), γ ′ is a compensation parameter for compensating for the steady-state deviation and the modeling error, similar to the compensation parameter γ described above.
[0144]
Also, the on-board identifier 227 also minimizes the identification error ide ', which is the deviation between the predicted auxiliary intake cam phase Pre_θmsi and the auxiliary intake cam phase θmsi, by the same sequential identification algorithm as the above-described on-board identifier 223. As described above (that is, so that the predicted auxiliary intake cam phase Pre_θmsi matches the auxiliary intake cam phase θmsi), the vectors of the matrix components α1 ′, α2 ′, βj ′ and the compensation parameter γ1 ′ of the model parameters in the above equation (29) θs ′ is identified.
[0145]
Specifically, the vector θs ′ (m) is calculated by the equations (30) to (35) shown in FIG. Equations (30) to (35) are configured in the same manner as Equations (8) to (13) described above, and a description thereof will be omitted.
[0146]
Next, the sliding mode controller (hereinafter, referred to as “SLD controller”) 228 will be described. The SLD controller 228 calculates the control input DUTY_msi based on the sliding mode control algorithm such that the sub intake cam phase θmsi converges to the target sub intake cam phase θmsi_cmd.
[0147]
Specifically, the control input DUTY_msi is calculated by the algorithm shown in equations (36) to (41) in FIG. That is, as shown by the equation (36) in the figure, if the following error Es' is defined as a deviation between the sub intake cam phase θmsi and the target sub intake cam phase θmsi_cmd, the switching function σs' and the switching function setting parameter Ss' Are defined as shown in equations (37) and (38) in FIG. The control input DUTY_msi is defined as the sum of the equivalent control input Ueq ′ and the reaching law input Urch ′, as shown in Expression (39) of FIG. It is defined as shown in equations (40) and (41) in FIG. As shown in Expression (39), the SLD controller 228 may control the sub intake cam phase θmsi to converge to the target sub intake cam phase θmsi_cmd. Therefore, the above-described valve control input Uvt is equal to the control input DUTY_msi. Omitted from the input component.
[0148]
As described above, also in the second SPAS controller 225, in the state predictor 226, the predicted auxiliary intake cam phase Pre_θmsi is calculated by the state prediction algorithm to which the compensation parameter γ1 ′ is added, and the compensation parameter γ1 ′ is identified by on-board identification. Therefore, the predicted auxiliary intake cam phase Pre_θmsi can be accurately calculated while compensating for the steady-state error and the modeling error.
[0149]
In addition, in the SLD controller 227, the auxiliary intake cam phase θmsi can be made to converge to the target auxiliary intake cam phase θmsi_cmd by the reaching law input Urch ′ and the equivalent control input Ueq ′, and at the same time, the convergence behavior and the convergence speed are It can be arbitrarily specified by setting the switching function setting parameter Ss'. Therefore, the convergence speed of the sub intake cam phase θmsi to the target sub intake cam phase θmsi_cmd can be set to an appropriate value according to the characteristics of the control target (system including the variable sub intake cam phase mechanism 70). Thereby, controllability can be improved.
[0150]
When the two switching function setting parameters Ss and Ss 'are set to values that satisfy the relationship of -1 <Ss <Ss'<0, the responsiveness of the control by the second SPAS controller 225 is reduced by the first SPAS. The control by the controller 221 can be enhanced, and the controllability of the sub intake cam phase controller 220 can be improved.
[0151]
Hereinafter, the engine control process including the valve timing control of the intake valve 6, which is executed by the ECU 2, will be described with reference to FIG. This figure shows the main control contents of the engine control processing. In this program, first, in step 1 (abbreviated as "S1" in the figure, the same applies hereinafter), the fuel control processing is executed. In this fuel control process, the required driving torque TRQ_eng, the main fuel injection rate Rt_Pre, the cylinder intake air amount Gcyl, the target intake air amount Gcyl_cmd, the fuel injection amounts TOUT_main, TOUT_sub, and the like are calculated according to the operating state of the engine 3. Yes, and the specific contents will be described later.
[0152]
Next, at step 2, a supercharging pressure control process is executed. This supercharging pressure control processing is for calculating a control input Dut_wg to the wastegate valve 10d according to the operating state of the engine 3, and the specific contents thereof will be described later.
[0153]
Next, at step 3, an intake valve control process is executed. This intake valve control process is for calculating the various control inputs DUTY_mi, DUTY_msi and DUTY_ssi # 2 to # 4 described above according to the operating state of the engine 3, and the specific contents thereof will be described later.
[0154]
Next, at step 4, an exhaust valve control process is executed. Although the detailed description of the exhaust valve control process is omitted, the above-described main exhaust cam phase variable mechanism 110, sub exhaust cam phase variable mechanism 120, and exhaust cam phase variable mechanism 130 vary depending on the operating state of the engine 3. The control inputs DUTY_me, DUTY_mse, and DUTY_sse # 2 to # 4 are calculated.
[0155]
Next, in step 5, a throttle valve control process is executed. This throttle valve control processing is for calculating the above-mentioned control input DUTY_th according to the operating state of the engine 3, and the specific contents thereof will be described later.
[0156]
Next, at step 6, after executing the ignition timing control processing, the program is terminated. Although the detailed description of the ignition timing control processing is omitted, the ignition timing of the air-fuel mixture by the ignition plug 5 is calculated in accordance with the operating state of the engine 3.
[0157]
Next, the fuel control process in step 1 will be described with reference to FIG. As shown in the drawing, in this program, first, in step 10, it is determined whether or not the intake / exhaust valve failure flag F_VLVNG or the throttle valve failure flag F_THNG is “1”. The intake / exhaust valve failure flag F_VLVNG is set to “1” when the variable intake valve drive device 40 or the variable exhaust valve drive device 90 has failed, and is set to “0” when both are normal. It is. The throttle valve failure flag F_THNG is set to “1” when the throttle valve mechanism 16 has failed, and is set to “0” when the throttle valve mechanism 16 is normal.
[0158]
If the result of the determination in step 10 is NO and the variable intake valve driving device 40, the variable exhaust valve driving device 90, and the throttle valve mechanism 16 are all normal, the process proceeds to step 11, and the required driving torque TRQ_eng is reduced by the engine speed. It is calculated by searching a map shown in FIG. 36 according to the number NE and the accelerator pedal opening AP.
[0159]
The predetermined values AP1 to AP3 of the accelerator opening AP in the figure are set so that the relationship of AP1>AP2> AP3 is established, and the predetermined value AP1 is set to the maximum value of the accelerator opening AP, that is, the maximum depression amount. Is set. As shown in the figure, in this map, in the range of NE ≦ NER2 (predetermined value), the required drive torque TRQ_eng is set to a larger value as the engine speed NE is higher and the accelerator opening AP is larger. Have been. This is because the required engine torque increases as the load on the engine 3 increases. When AP = AP1, the required drive torque TRQ_eng is set to its maximum value in the range of NER1 (predetermined value) <NE ≦ NER2. Further, in the range of NER2 <NE, the required drive torque TRQ_eng is set to a larger value as the accelerator opening AP is larger, and is set to a smaller value as the engine speed NE is higher. . This is due to the output characteristics of the engine torque with respect to the engine speed NE.
[0160]
In step 12 following step 11, it is determined whether or not the required drive torque TRQ_eng calculated in step 11 is smaller than a predetermined stratified combustion operation threshold value TRQ_disc. Note that the stratified combustion operation refers to an operation in which the main fuel injection valve 4 performs fuel injection into the cylinder during the compression stroke to perform stratified combustion of the air-fuel mixture.
[0161]
If the determination result in step 12 is YES and the engine 3 is to perform stratified charge combustion operation, the process proceeds to step 13 in which a target air-fuel ratio KCMD_disc for stratified charge combustion operation is searched in a table (not shown) according to the required drive torque TRQ_eng. It is calculated by the following. In this table, the target air-fuel ratio KCMD_disc for stratified charge combustion operation is set to a value in a predetermined extremely lean region (for example, A / F = 30 to 40).
[0162]
Next, the routine proceeds to step 14, in which the target air-fuel ratio KCMD is set to the target air-fuel ratio KCMD_disc for stratified charge combustion operation, and in step 15, the main fuel injection rate Rt_Pre is set to a predetermined maximum value Rtmax (100%). Thus, the fuel injection by the auxiliary fuel injection valve 15 is stopped, as described later. Proceeding to step 16, the cylinder intake air amount Gcyl and the target intake air amount Gcyl_cmd are calculated.
[0163]
The cylinder intake air amount Gcyl and the target intake air amount Gcyl_cmd are specifically calculated by a program shown in FIG. That is, first, in step 30 of the figure, the cylinder intake air amount Gcyl is calculated by the aforementioned equation (1).
[0164]
Next, at step 31, the basic value Gcyl_cmd_base of the target intake air amount is calculated by searching a map shown in FIG. 38 according to the engine speed NE and the required drive torque TRQ_eng. It should be noted that the predetermined values TRQ_eng1 to TRQ_eng1 of the required driving torque in this map are set such that the relationship of TRQ_eng1>TRQ_eng2> TRQ_eng3 is satisfied. As shown in the figure, the basic value Gcyl_cmd_base of the target intake air amount is set to a larger value as the engine speed NE is higher or the required drive torque TRQ_eng is larger. This is because a larger engine output is required as the load on the engine 3 is larger, so that a larger intake air amount is required.
[0165]
Next, in step 32, the air-fuel ratio correction coefficient Kgcyl_af is calculated by searching a table shown in FIG. 39 according to the target air-fuel ratio KCMD. In this table, the air-fuel ratio correction coefficient Kgcyl_af is set to a larger value as the target air-fuel ratio KCMD is on the rich side. This is because the required intake air amount becomes smaller as the air-fuel ratio of the air-fuel mixture is controlled to be richer. The value KCMDST in the figure is a value corresponding to the stoichiometric air-fuel ratio.
[0166]
Next, the routine proceeds to step 33, where the product of the basic value of the target intake air amount and the air-fuel ratio correction coefficient (Kgcyl_af · Gcyl_cmd_base) is set as the target intake air amount Gcyl_cmd, and then this program ends.
[0167]
Referring back to FIG. 35, after executing step 16 as described above, the process proceeds to step 17, where a fuel injection control process is executed. In the fuel injection control process, specifically, control inputs to the main and auxiliary fuel injection valves 4 and 15 are calculated as follows.
[0168]
First, a main fuel injection amount TOUT_main which is a fuel injection amount of the main fuel injection valve 4 and a sub fuel injection amount TOUT_sub which is a fuel injection amount of the sub fuel injection valve 15 are calculated. That is, the final total fuel injection amount TOUT for each cylinder is calculated for each cylinder based on the operating state of the engine 3 and the aforementioned target air-fuel ratio KCMD, and then the main fuel injection amount TOUT is calculated by the following equations (42) and (43). Calculate the auxiliary fuel injection amounts TOUT_main and TOUT_sub, respectively.
TOUT_main = [TOUT · Rt_Pre] / 100 (42)
TOUT_sub = [TOUT · (100−Rt_Pre)] / 100 (43)
Referring to this equation (43), when Rt_Pre = Rtmax (100%), TOUT_sub = 0, and it can be seen that the fuel injection by the auxiliary fuel injection valve 15 is stopped.
[0169]
Next, a control input to the main / sub fuel injection valves 4 and 15 is calculated by searching a table (not shown) according to the calculated main / sub fuel injection amounts TOUT_main and TOUT_sub. After executing step 17 as described above, the present program ends.
[0170]
On the other hand, if the decision result in the step 12 is NO, it is determined that the engine 3 should be the premixed lean operation of the uniform combustion operation instead of the stratified charge combustion operation, and the process proceeds to a step 18, where the target empty for the premixed lean operation is performed. The fuel ratio KCMD_lean is calculated by searching a table (not shown) according to the required drive torque TRQ_eng. In this table, the target air-fuel ratio KCMD_lean for the premixed lean operation is set to a value in a predetermined lean region (for example, A / F = 18 to 21).
[0171]
Next, proceeding to step 19, after setting the target air-fuel ratio KCMD to the target air-fuel ratio KCMD_lean for the premixed lean operation, in step 20, the main fuel injection rate Rt_Pre is shown in FIG. 40 according to the required drive torque TRQ_eng. It is calculated by searching the table. In the following tables and maps including the same figure, various predetermined values TRQ_idle, TRQ_disc, TRQott, and TRQ1 to TRQ4 of the required drive torque TRQ_eng have a relation of TRQ_idle <TRQ_disc <TRQ1 <TRQott <TRQ2 <TRQ3 <TRQ4, respectively. It is set to a value that holds. TRQ_idle represents a predetermined idle operation value (a value that defines a predetermined first load region).
[0172]
As shown in the drawing, in this table, in the range of TRQ1 <TRQ_eng <TRQ4, the main fuel injection rate Rt_Pre is set to a smaller value as the required drive torque TRQ_eng is larger. This is for the following reason. That is, by controlling the supercharging pressure Pc to increase as the required driving torque TRQ_eng increases, the temperature of the intake air increases, and knocking is more likely to occur. Accordingly, in order to avoid such knocking, it is necessary to increase the fuel injection amount TOUT_sub of the auxiliary fuel injection valve 15 to increase the cooling effect of the intake air by the fuel vaporization cooling device 12 described above. The fuel injection rate Rt_Pre is set as described above.
[0173]
In this table, the main fuel injection rate Rt_Pre is set to a predetermined minimum value Rtmin (10%) when the required driving torque TRQ_eng is equal to or greater than a predetermined value TRQ4, and is set to a maximum value when the required driving torque TRQ_eng is equal to or less than the predetermined value TRQ1. The value is set to the value Rtmax.
[0174]
After the execution of step 20, the program ends after executing steps 16 and 17 described above.
[0175]
On the other hand, if the decision result in the step 10 is YES and one of the variable intake valve driving device 40, the variable exhaust valve driving device 90 and the throttle valve mechanism 16 is out of order, the process proceeds to a step 21, and the required driving torque TRQ_eng. Is set to a predetermined value TRQ_fs for failure. Thereafter, the routine proceeds to step 22, where the main fuel injection rate Rt_Pre is set to the aforementioned maximum value Rtmax. Next, as described above, after executing steps 16 and 17, the program is terminated.
[0176]
Next, the above-described supercharging pressure control processing will be described with reference to FIG. As shown in the figure, in this program, first, in step 40, it is determined whether or not the above-described intake / exhaust valve failure flag F_VLVNG or the throttle valve failure flag F_THNG is “1”.
[0177]
When the result of this determination is NO and the variable intake valve driving device 40, the variable exhaust valve driving device 90 and the throttle valve mechanism 16 are all normal, the routine proceeds to step 41, where the engine start flag F_ENGSTART is "1". It is determined whether or not. The engine start flag F_ENGSTART is set by determining in an unillustrated determination process whether or not the engine is being started, that is, whether cranking is being performed, in accordance with the engine speed NE and the output signal of the IG · SW 36. Yes, specifically, it is set to "1" when it is determined that the engine is being started, and to "0" otherwise.
[0178]
If the decision result in the step 41 is YES and the engine is being started, the process proceeds to a step 43, wherein the control input Dut_wg to the wastegate valve 10d is set to a predetermined full opening value Dut_wgmax, and then the present program is ended. Thereby, the wastegate valve 10d is controlled to the fully open state, and the supercharging operation by the turbocharger device 10 is substantially stopped.
[0179]
On the other hand, if the decision result in the step 41 is NO and the engine is not being started, the process proceeds to a step 42, where it is determined whether or not the catalyst warm-up flag F_CATHOT is "1". The catalyst warm-up flag F_CATHOT is set to “1” when the catalyst warm-up control is being performed after the engine is started, and is set to “0” otherwise. This catalyst warm-up control is for rapidly activating the catalyst after the engine is started, and is started immediately after the end of the engine start. In the catalyst warm-up control, when the execution time Tcat reaches a predetermined value, the control ends, and the catalyst warm-up flag F_CATHOT is set to “0”.
[0180]
If the determination result in step 42 is YES and the catalyst warm-up control is being performed, the process proceeds to step 44, in which the control input Dut_wg to the wastegate valve 10d is set to the above-described full-open value Dut_wgmax as in step 43. Then, the program ends.
[0181]
On the other hand, if the decision result in the step 42 is NO and the engine is not being started and the catalyst warm-up control is not being performed, the process proceeds to a step 45, wherein the basic value Dut_wg_bs of the control input Dut_wg is changed according to the required drive torque TRQ_eng as shown in FIG. It is calculated by searching the indicated table.
[0182]
As shown in the drawing, in this table, the basic value Dut_wg_bs is set to a smaller value as the required drive torque TRQ_eng becomes larger in the range of TRQ1 <TRQ_eng <TRQ2. This is because, as the required drive torque TRQ_eng is larger, it is necessary to further increase the supercharging pressure Pc for the purpose of increasing the charging efficiency due to supercharging. The basic value Dut_wg_bs is set to a predetermined fully-closed value Dut_wgmin in the range of TRQ2 ≦ TRQ_eng ≦ TRQ3, which increases the supercharging effect in accordance with the load of the engine 3 being in a high load range. To get the most out of it. Further, the basic value Dut_wg_bs is set to a smaller value as the required drive torque TRQ_eng is larger in a range of TRQ3 <TRQ_eng, in order to avoid occurrence of knocking.
[0183]
Next, at step 46, the target supercharging pressure Pc_cmd is calculated by searching a table shown in FIG. 43 according to the required drive torque TRQ_eng. As shown in the drawing, in this table, the target supercharging pressure Pc_cmd is set to a larger value as the required drive torque TRQ_eng is larger in the range of TRQ_idle <TRQ_eng <TRQ2. This is to further increase the charging efficiency due to supercharging as described above. Further, the target supercharging pressure Pc_cmd is set to a predetermined fully closed value Dut_wgmin in a range of TRQ2 ≦ TRQ_eng ≦ TRQ3, in order to maximize the supercharging effect as described above. Further, in the range of TRQ3 <TRQ_eng <TRQ4, the target supercharging pressure Pc_cmd is set to a smaller value as the required drive torque TRQ_eng is larger, in order to avoid occurrence of knocking. In addition, Patm in the figure shows the atmospheric pressure, and this point is the same in the following.
[0184]
Next, the process proceeds to a step 47, wherein the control input Dut_wg is calculated by the IP control algorithm shown in the following equation (44), and the program is terminated. As a result, feedback control is performed so that the supercharging pressure Pc converges to the target supercharging pressure Pc_cmd.
Dut_wg = Dut_wg_bs + Kpwg · Pc + Kiwg · (Pc−Pc_cmd) (44)
Here, Kpwg represents a P-term gain, and Kiwg represents an I-term gain.
[0185]
On the other hand, if the decision result in the step 40 is YES and one of the variable intake valve driving device 40, the variable exhaust valve driving device 90 and the throttle valve mechanism 16 is out of order, the process proceeds to a step 48, and the step 43 is executed. , 44, the control input Dut_wg to the wastegate valve 10d is set to the fully open value Dut_wgmax, and then this program is ended.
[0186]
Next, the above-described intake valve control process in step 3 will be described with reference to FIGS. As shown in the figure, in this program, first, in step 60, it is determined whether or not the above-described intake / exhaust valve failure flag F_VLVNG is “1”. When both the device 40 and the variable exhaust valve driving device 90 are normal, the routine proceeds to step 61, where it is determined whether or not the above-described engine start flag F_ENGSTART is “1”.
[0187]
If the determination result is YES and the engine is being started, the routine proceeds to step 62, where a target main intake cam phase θmi_cmd which is a target value of the main intake cam phase θmi is set to a predetermined idle value θmi_idle.
[0188]
Next, the routine proceeds to step 63, where the target auxiliary intake cam phase θmsi_cmd is set to a predetermined starting value θmsi_st. This start value θmsi_st is set as a predetermined value for the late closing of the intake valve 6. Thereafter, the routine proceeds to step 64, where the target inter-intake cam phase θssi # i_cmd (# i = # 2 to # 4) is set to a value of 0.
[0189]
Next, the routine proceeds to step 65 in FIG. 45, where the control input DUTY_mi to the main intake cam phase variable mechanism 60 is calculated by searching a table (not shown) according to the target main intake cam phase θmi_cmd. Thereafter, in step 66, the control input DUTY_msi to the variable sub intake cam phase mechanism 70 is calculated by searching a table (not shown) according to the target main intake cam phase θmi_cmd. In this step 66, the control input DUTY_msi may be calculated in the same manner as in step 74 described later.
[0190]
Next, in step 67, the control input DUTY_ssi # i to the inter-intake cam phase variable mechanism 80 is calculated by searching a table (not shown) according to the target inter-intake cam phase θssi # i_cmd, and then this program ends. I do.
[0191]
Returning to FIG. 44, if the decision result in the step 61 is NO and the engine is not being started, the routine proceeds to a step 68, where it is determined whether or not the above-mentioned catalyst warm-up flag F_CATHOT is "1". If the determination result is YES and the catalyst warm-up control is being performed, the routine proceeds to step 69, where the target main intake cam phase θmi_cmd is set to the above-mentioned predetermined idling value θmi_idle.
[0192]
Next, the routine proceeds to step 70, where the catalyst warm-up value θmsi_cw of the target auxiliary intake cam phase is calculated by searching a table shown in FIG. 46 according to the execution time Tcat of the above-mentioned catalyst warm-up control. The value θmsiott in the figure indicates the Otto phase value (= cam angle 90 deg) of the sub intake cam phase θmsi at which the valve timing of the intake valve 6 becomes the same as the Otto intake cam, and this point is the same in the following description. It is.
[0193]
Next, in step 71, the target auxiliary intake cam phase θmsi_cmd is set to the catalyst warm-up value θmsi_cw, and in step 72, similarly to step 64, the target inter-intake cam phase θssi # i_cmd (# i = #) 2 to # 4) are all set to the value 0.
[0194]
Then, the process proceeds to a step 73 in FIG. 45, wherein a control input DUTY_mi to the main intake cam phase variable mechanism 60 is calculated according to the target main intake cam phase θmi_cmd and the main intake cam phase θmi. This control input DUTY_mi is calculated by the same algorithm as the control algorithm by the second SPAS controller 225 described above.
[0195]
Next, at step 74, a control input DUTY_msi to the sub intake cam phase variable mechanism 70 is calculated by the control algorithm of the second SPAS controller 225. That is, the control input DUTY_msi is calculated by applying the above-described prediction algorithm of Expression (29), the identification algorithm of Expressions (30) to (35), and the sliding mode control algorithm of Expressions (36) to (41). I do.
[0196]
Next, in step 75, a control input DUTY_ssi # i (# i = # i) to the inter-intake cam phase variable mechanism 80 according to the target inter-intake cam phase θssi # i_cmd and the inter-intake cam phase θssi # i calculated in step 72. After calculating (# 2 to # 4), this program ends. The control input DUTY_ssi # i is calculated by the same algorithm as the control algorithm used for calculating the control input DUTY_msi.
[0197]
Returning to FIG. 44, if the determination result in step 68 is NO and the engine is not being started and the catalyst warm-up control is not being performed, the process proceeds to step 76, in which the normal operation value θmi_drv of the target main intake cam phase is calculated by requesting the required drive torque TRQ_eng and It is calculated by searching a map shown in FIG. 47 according to the engine speed NE.
[0198]
In the figure, the predetermined values NE1 to NE3 of the engine speed NE are set so that the relationship of NE1>NE2> NE3 is satisfied, and this point is the same in the following. In this map, the normal operation value θmi_drv is set to a more advanced value as the required drive torque TRQ_eng is larger or the engine speed NE is higher. This is to ensure the engine output appropriately by advancing the main intake cam phase θmi and advancing the opening and closing timing of the intake valve 6.
[0199]
Next, in step 77, after setting the target main intake cam phase θmi_cmd to the above-mentioned normal operation value θmi_drv, the routine proceeds to step 78, where the basic value θmsi_base of the sub intake cam phase described above is calculated according to the required driving torque TRQ_eng. This is calculated by searching the table shown in FIG.
[0200]
As shown in the drawing, in this table, the basic value θmsi_base is set to a constant value on the late closing side in the range of TRQ_eng <TRQ_disc, that is, in the stratified combustion operation range of the engine 3. This is to stabilize the combustion state in a low load region where the stratified combustion operation is performed. Further, in the range of TRQ_disc ≦ TRQ_eng ≦ TRQott, the basic value θmsi_base is set such that the larger the required driving torque TRQ_eng, the smaller the degree of late closing is. This is because the larger the required drive torque TRQ_eng is, the larger the amount of fuel blown back into the intake manifold due to the degree of the late closing of the intake valve 6 is, so as to avoid this. Further, when TRQ_eng = TRQott (thresholds of the first and second load regions), the basic value θmsi_base is set to the Otto phase value θmsiott (a value corresponding to the predetermined timing).
[0201]
Further, the basic value θmsi_base is set such that the larger the required driving torque TRQ_eng is, the larger the degree of early closing becomes in the range of TRQott <TRQ_eng <TRQ2. This increases the combustion efficiency by the high expansion ratio cycle operation. That's why.
[0202]
In the range of TRQ2 ≦ TRQ_eng <TRQ4, the basic value θmsi_base is set such that the larger the required driving torque TRQ_eng, the smaller the degree of early closing of the intake valve 6 becomes. This is for the following reason. That is, in a high load region such as TRQ2 ≦ TRQ_eng <TRQ4, as described later, the supercharging operation is restricted in order to avoid the occurrence of knocking. If the degree of early closing of the intake valve 6 is controlled to be large in this state, the generated torque is reduced. Therefore, in order to compensate for such a decrease in the generated torque, the degree of early closing of the intake valve 6 is set to be smaller as the required drive torque TRQ_eng is larger.
[0203]
In a step 79 following the step 78, the target auxiliary intake cam phase θmsi_cmd is calculated by the control algorithm of the first SPAS controller 221 described above. That is, by applying the above-described prediction algorithm of Expression (7), the identification algorithm of Expressions (8) to (13), and the sliding mode control algorithm of Expressions (15) to (21), the target auxiliary intake cam phase θmsi_cmd Is calculated.
[0204]
Next, at step 80, the target inter-intake cam phase θssi # i_cmd (# i = # 2 to # 4) is calculated by the control algorithm of the inter-intake cam phase controller 230 described above. Next, after executing steps 73 to 75 in FIG. 45 as described above, the present program is terminated.
[0205]
Returning to FIG. 44, if the determination result in step 60 is YES and the variable intake valve driving device 40 or the variable exhaust valve driving device 90 has failed, the process proceeds to step 81, where the target main intake cam phase θmi_cmd is set to a predetermined value. After setting to the idling value θmi_idle, the routine proceeds to step 82, where the target auxiliary intake cam phase θmsi_cmd is set to a predetermined failure value θmsi_fs.
[0206]
Then, the process proceeds to a step 83, wherein the target inter-intake cam phase θssi # i_cmd (# i = # 2 to # 4) is set to a value of 0, similarly to the steps 64 and 72 described above. Thereafter, as described above, after executing steps 65 to 67 in FIG. 45, the program ends.
[0207]
Next, the throttle valve control processing in step 5 described above will be described with reference to FIG. As shown in the drawing, in this program, first, in step 120, it is determined whether or not the above-described intake / exhaust valve failure flag F_VLVNG is “1”. When both the device 40 and the variable exhaust valve driving device 90 are normal, the routine proceeds to step 121, where it is determined whether or not the aforementioned engine start flag F_ENGSTART is “1”.
[0208]
If the determination result is YES and the engine is being started, the routine proceeds to step 122, where the target opening TH_cmd is set to a predetermined starting value THcmd_st. This predetermined start value THcmd_st is set to a value slightly larger than an idle value THcmd_idle described later. Next, the routine proceeds to step 123, where the control input DUTY_th to the throttle valve mechanism 16 is calculated, followed by terminating the present program. The control input DUTY_th is specifically calculated by searching a table (not shown) according to the target opening TH_cmd.
[0209]
On the other hand, if the decision result in the step 121 is NO and the engine is not being started, the routine proceeds to a step 124, where it is determined whether or not the above-mentioned catalyst warm-up flag F_CATHOT is "1". If the determination result is YES and the catalyst warm-up control is being performed, the process proceeds to step 125, and the catalyst warm-up value THcmd_ast of the target opening is set to the value shown in FIG. 50 according to the catalyst warm-up control execution time Tcat described above. It is calculated by searching the indicated table.
[0210]
The value THcmd_idle in the figure indicates an idle value used during idle operation. As shown in the drawing, in this table, the catalyst warm-up value THcmd_ast is set to a larger value as the execution time Tcat is shorter until the execution time Tcat reaches the predetermined value Tcat1, and the execution time Tcat Has reached the predetermined value Tcat1, the idle value THcmd_idle is set.
[0211]
Next, the routine proceeds to step 126, where the target opening TH_cmd is set to the catalyst warm-up value THcmd_ast, and then, as described above, step 123 is executed, followed by terminating the present program.
[0212]
On the other hand, if the decision result in the step 124 is NO, that is, the engine is not being started and the catalyst warm-up control is not being performed, the routine proceeds to a step 127, where the normal operation value THcmd_drv of the target opening is set to the required drive torque TRQ_eng and the engine speed NE. Accordingly, the calculation is performed by searching the map shown in FIG.
[0213]
As shown in the figure, in this map, the normal operation value THcmd_drv is set to a larger value as the required drive torque TRQ_eng is larger or as the engine speed NE is higher. This is because a higher load of the engine 3 requires a larger amount of intake air to secure a larger engine output.
[0214]
Next, in step 128, the target opening TH_cmd is set to the normal operation value THcmd_drv, and then, as described above, step 123 is executed, and then the program is terminated.
[0215]
On the other hand, if the decision result in the step 120 is YES and the variable intake valve driving device 40 or the variable exhaust valve driving device 90 is out of order, the process proceeds to a step 129, in which the failure value THcmd_fs of the target opening is set to the accelerator opening. It is calculated by searching a map shown in FIG. 52 according to the degree AP and the engine speed NE. As shown in the figure, in this map, the failure value THcmd_fs is set to a larger value as the accelerator opening AP is larger or the engine speed NE is higher. This is based on the same reason as described in the calculation of the normal operation value THcmd_drv.
[0216]
Next, the routine proceeds to step 130, where the target opening TH_cmd is set to the above-mentioned failure value THcmd_fs. Next, as described above, step 123 is executed, and then this program is terminated.
[0219]
By the above control processing, various control inputs DUTY_mi, DUTY_msi, DUTY_ssi # i, DUTY_me, DUTY_mse, DUTY_sse # i, and DUTY_th are any of a pulse signal, a current signal, and a voltage signal having a duty ratio according to the calculation result. Set to one.
[0218]
The operation when the above-described engine control is executed will be described with reference to FIG. 53 for each of the following ranges of the required drive torque TRQ_eng of (L1) to (L6).
[0219]
(L1) TRQ_iddle ≦ TRQ_eng <TRQ_disc range
In this range, the sub intake cam phase θmsi is controlled to a substantially constant value on the late closing side by setting the basic value θmsi_base described above. Further, by controlling the intake air amount so as not to be throttled by the throttle valve 17, the intake pipe absolute pressure PBA is controlled to a substantially constant value slightly lower than the atmospheric pressure Patm. Further, the cylinder intake air amount Gcyl is controlled to a substantially constant value, and the intake pipe absolute pressure PBA is controlled to a substantially constant value lower than the atmospheric pressure Patm. Further, the main fuel injection rate Rt_Pre is set to the maximum value Rtmax, the target air-fuel ratio KCMD is set to a value in the extremely lean region, and the stratified charge combustion operation is executed.
[0220]
(L2) TRQ_disc ≦ TRQ_eng ≦ TRQ1
In this range, by setting the above-described basic value θmsi_base, the auxiliary intake cam phase θmsi is controlled to a value on the close side much later than the value in the range of (L1), and the required drive torque TRQ_eng is large. The more the degree of late closing is controlled, the smaller the degree of late closing becomes. Further, the cylinder intake air amount Gcyl is controlled to a value smaller than the value in the range of (L1), and is controlled to be larger as the required drive torque TRQ_eng is larger. Further, the target air-fuel ratio KCMD is controlled so as to maintain the above-described lean range value richer than the value in the above (L1) range, and the intake pipe absolute pressure PBA and the main fuel injection rate Rt_Pre are both Control is performed so as to maintain the value in the range of (L1).
[0221]
(L3) TRQ1 <TRQ_eng ≦ TRQott
In this range, the sub intake cam phase θmsi is controlled to have the same tendency as in the range of (L2) by setting the basic value θmsi_base described above. In particular, when TRQ_eng = TRQott, the sub intake cam phase θmsi is controlled to be the Otto phase value θmsiott. That is, the engine 3 is operated in an Otto cycle. Further, the target air-fuel ratio KCMD and the cylinder intake air amount Gcyl are also controlled in the same tendency as in the range of (L2). Further, in this range, the supercharging operation by the turbocharger device 10 is executed, whereby the intake pipe absolute pressure PBA is controlled to be higher as the required drive torque TRQ_eng is larger. Further, the main fuel injection rate Rt_Pre is controlled to be smaller as the required drive torque TRQ_eng is larger. That is, the fuel injection amount TOUT_sub of the auxiliary fuel injection valve 15 is controlled to be a larger value as the required drive torque TRQ_eng is larger. This is for obtaining the cooling effect of the intake air by the fuel vaporization cooling device 12.
[0222]
(L4) TRQott <TRQ_eng <TRQ2
In this range, the sub intake cam phase θmsi is controlled such that the greater the required drive torque TRQ_eng, the greater the early closing degree. This is because the combustion efficiency is increased by the high expansion ratio cycle operation as described above. Further, the cylinder intake air amount Gcyl, the target air-fuel ratio KCMD, the main fuel injection rate Rt_Pre, and the intake pipe absolute pressure PBA are controlled so as to show the same tendency as in the range of (L3). In particular, similarly to the above, the intake pipe absolute pressure PBA is controlled to be higher as the required drive torque TRQ_eng is larger. This is because if the auxiliary intake cam phase θmsi is controlled to the early closing side, the generated torque is reduced. Therefore, the charging efficiency is increased by supercharging and the generated torque is increased for the purpose of compensation.
[0223]
(L5) TRQ2 ≦ TRQ_eng <TRQ4
In this range, the auxiliary intake cam phase θmsi is controlled such that the greater the required drive torque TRQ_eng, the earlier the degree of closing becomes smaller, and as a result, the effective compression volume increases. This is because, as described above, if the degree of early closing of the intake valve 6 is controlled to be large in a state where the charging efficiency is reduced due to the limitation of the supercharging operation, the generated torque is reduced. This is because the reduction of the generated torque is compensated by controlling the sub intake cam phase θmsi.
[0224]
Further, the intake pipe absolute pressure PBA is controlled to maintain a constant value in a range of TRQ2 ≦ TRQ_eng ≦ TRQ3, and becomes a lower value in a range of TRQ3 <TRQ_eng <TRQ4 as the required drive torque TRQ_eng is larger. Is controlled as follows. Further, similarly to the range of (L3), the main fuel injection rate Rt_Pre is controlled to be smaller as the required drive torque TRQ_eng is larger. As described above, in the range of (L5), as the required driving torque TRQ_eng is larger, the supercharging operation by the turbocharger device 10 is restricted, and the cooling effect by the fuel vaporization cooling device 12 is increased. Thus, occurrence of knocking can be avoided without performing retard control of the ignition timing. In the case of a conventional engine with a turbocharger device, knocking occurs unless retard control of the ignition timing is performed in the range of (L5).
[0225]
(L6) TRQ4 ≦ TRQ_eng range
In this range, the extremely high load range prevents the occurrence of knocking with the above-described restriction of the supercharging operation by the turbocharger device 10 and the cooling effect by the fuel vaporization cooling device 12, so that the ignition timing retard control is performed. Is executed. That is, the target air-fuel ratio KCMD is controlled to be richer as the required drive torque TRQ_eng is larger. At the same time, the sub intake cam phase θmsi is controlled to be the Otto phase value θmsiott, the cylinder intake air amount Gcyl is controlled to be substantially constant, the main fuel injection rate Rt_Pre is controlled to the minimum value Rtmin, The intake pipe absolute pressure PBA is controlled to maintain a substantially constant value.
[0226]
As described above, according to the valve timing control device 1 of the present embodiment, when the basic value θmsi_base of the target auxiliary intake cam phase is in the range of TRQ_idle ≦ TRQ_eng <TRQott (predetermined first load range), that is, in the low load range, In the range of TRQott <TRQ_eng <TRQ4 (predetermined second load range), that is, in the high load range, the value is set to the value on the early closing side in accordance with the required driving torque TRQ_eng. Is set. Then, the sub intake cam phase controller 220 controls the sub intake cam phase θmsi to be the basic value θmsi_base. That is, the closing timing of the intake valve 6 is controlled to the late closing side or the early closing side in accordance with the required drive torque TRQ_eng. As a result, the amount of air sucked into the cylinder via the intake valve 6 is controlled. You. As described above, the intake air amount is controlled in accordance with the load of the engine 3, so that the intake air amount can be controlled more precisely and more precisely than in the past, and the excess and deficiency of the intake air amount can be avoided. As a result, both the combustion state and the exhaust gas characteristics can be maintained in a favorable state.
[0227]
In the low load range, the engine 3 is operated in a high expansion ratio cycle in which the expansion ratio is higher than the compression ratio due to the late closing of the intake valve 6, so that it is not necessary to reduce the intake air amount with the throttle valve 17, for example. Thus, while avoiding pumping loss, the intake air amount can be set to an appropriate value corresponding to a low load, and fuel efficiency can be improved. In addition, unlike the case where the intake valve 6 is driven by the Otto intake cam and the case where the intake valve is quickly closed in the low load range, even when the intake temperature or the engine temperature is low, the generation and combustion of the fuel in the cylinder are performed. Instability of the state can be avoided, and a favorable combustion state can be ensured.
[0228]
Further, in the high load range, the engine 3 is operated at a high expansion ratio cycle due to the early closing of the intake valve 6, so that unlike the case where the intake valve 6 is driven by the Otto intake cam or the case where the intake valve 6 is closed late, the intake valve 6 is moved into the intake manifold. Of fuel blow-back and fuel adhesion to the intake manifold inner wall, etc., and as a result, control accuracy of air-fuel ratio control and torque control can be improved, and exhaust gas characteristics and operability are improved. In addition, the life of the intake system device such as the intake valve 6 can be extended.
[0229]
In addition to this, since the variable intake valve driving device 40 is constituted by a hydraulically driven type, for example, a variable intake valve driving device of a type that drives the valve body of the intake valve 6 by the electromagnetic force of a solenoid is used. The intake valve 6 can be reliably opened and closed even in a higher load region as compared with the case where the intake valve 6 is used, power consumption can be reduced, and the operation sound of the intake valve 6 can be reduced.
[0230]
Further, the variable intake valve driving device 40 is configured such that not only the closing timing of the intake valve 6 but also the valve lift can be freely changed in the range of the sub intake cam phase θmsi = 120 to 180 deg. By controlling the lift amount to a smaller value, the flow velocity of the intake air flowing into the combustion chamber can be increased, and the in-cylinder flow can be further increased. Thereby, the combustion efficiency can be improved.
[0231]
Furthermore, the combination of the main / sub intake cams 43 and 44, the main / sub intake camshafts 41 and 42, the link mechanism 50 and the intake valve drive mechanism 50 including the intake rocker arm 51, and the sub intake cam phase variable mechanism 70 provide It is possible to realize a configuration in which the sub intake cam phase θmsi can be freely changed, that is, a configuration in which the valve closing timing and the valve lift of the intake valve 6 can be freely changed.
[0232]
Further, in the embodiment, the intake valve 6 is controlled to the late closing side in the range of TRQ_eng <TRQott (predetermined third load range). Instead, the intake valve 6 is controlled to the early closing side in this range. May be. In this case, the ECU 2 (valve lift amount determining means) sets the above-described auxiliary intake cam phase θmsi in the range of θmsi = 120 to 180 deg in accordance with the required drive torque TRQ_eng, thereby setting the valve lift amount to What is necessary is just to control to a value smaller than the maximum value. More specifically, the control may be performed such that the smaller the required driving torque TRQ_eng is, the smaller the valve lift amount is. In the case of such control, the combustion can be accelerated by increasing the flow velocity of the intake air flowing into the combustion chamber and increasing the in-cylinder flow. As a result, even when the intake air temperature or the engine temperature is low, it is possible to avoid the above-described liquefaction of fuel due to the early closing of the intake valve 6 in a low load region. Thereby, the combustion state can be stabilized.
[0233]
In the case where high responsiveness is not required in the variable sub-intake cam phase mechanism 70 (for example, in the above-described intake valve control process, the intake valve 6 needs to be controlled to only one of the late closing side and the early closing side). Instead of the hydraulic piston mechanism 73 and the motor 74, a hydraulic pump 63 and an electromagnetic valve mechanism 64 may be used similarly to the main intake cam phase variable mechanism 60. In that case, the control device 1 may be configured as shown in FIG.
[0234]
As shown in the figure, the control device 1 includes a DUTY_msi calculator 300 and a throttle valve opening controller 301 instead of the DUTY_th calculator 200 and the sub intake cam phase controller 220 in the embodiment. The DUTY_msi calculating section 300 calculates a target auxiliary intake cam phase θmsi_cmd by searching a table according to the required drive torque TRQ_eng, and then searches the table according to the calculated target auxiliary intake cam phase θmsi_cmd. Thus, the control input DUTY_msi is calculated. In addition, the throttle valve opening controller 301 calculates the target opening TH_cmd according to the cylinder intake air amount Gcyl and the target intake air amount Gcyl_cmd by the same control algorithm as the first SPAS controller 221 described above, and then calculates the calculated target target TH_cmd. According to the opening TH_cmd, the control input DUTY_th is calculated by the same control algorithm as that of the second SPAS controller 225. With the above configuration, even when the response of the variable sub intake cam phase mechanism 70 is low, it is possible to appropriately control the sub intake cam phase θmsi while avoiding the influence thereof.
[0235]
Further, the embodiment is an example in which both the first SPAS controller 221 and the second SPAS controller 225 are provided as the auxiliary intake cam phase controller 220, but instead, a controller having only the first SPAS controller 221 is used. Is also good. In that case, the control input DUTY_msi may be calculated according to the target auxiliary intake cam phase θmsi_cmd calculated by the first SPAS controller 221 by referring to a table, for example.
[0236]
【The invention's effect】
As described above, according to the valve timing control device of the present invention, the intake air amount can be precisely and finely controlled, so that both the combustion state and the exhaust gas characteristics can be maintained in a favorable state.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an internal combustion engine to which a valve timing control device according to one embodiment of the present invention is applied.
FIG. 2 is a diagram showing a schematic configuration of a variable intake valve driving device and a variable exhaust valve driving device of an internal combustion engine.
FIG. 3 is a diagram showing a schematic configuration of a valve timing control device.
FIG. 4 is a diagram showing a schematic configuration of a fuel vaporization cooling device.
FIG. 5 is a schematic plan view showing a schematic configuration of a variable intake valve driving device and a variable exhaust valve driving device.
FIG. 6 is a diagram showing a schematic configuration of an intake valve driving mechanism of the variable intake valve driving device.
FIG. 7 is a diagram showing a schematic configuration of a main intake cam phase variable mechanism.
FIG. 8 is a diagram showing a schematic configuration of a sub intake cam phase variable mechanism.
FIG. 9 is a diagram showing a schematic configuration of a modified example of the sub intake cam phase variable mechanism.
FIG. 10 is a view showing a schematic configuration of a variable phase mechanism between intake cams.
FIG. 11 is a diagram for explaining cam profiles of a main intake cam and a sub intake cam.
12A is a diagram illustrating an operation state of an intake valve driving mechanism when the auxiliary intake cam phase θmsi = 0 deg, and FIG. 12B is a diagram illustrating a valve lift curve and the like for explaining the operation of the intake valve.
13A is a diagram illustrating an operation state of an intake valve driving mechanism when the auxiliary intake cam phase θmsi = 90 deg, and FIG. 13B is a diagram illustrating a valve lift curve and the like for explaining the operation of the intake valve.
14A is a diagram illustrating an operation state of an intake valve driving mechanism when the auxiliary intake cam phase θmsi = 120 deg, and FIG. 14B is a diagram illustrating a valve lift curve and the like for explaining the operation of the intake valve.
15A is a diagram illustrating an operation state of an intake valve driving mechanism when the auxiliary intake cam phase θmsi = 180 deg, and FIG. 15B is a diagram illustrating a valve lift curve and the like for explaining the operation of the intake valve.
FIG. 16 is a diagram showing changes in valve lift and valve timing for explaining the operation of the intake valve when the auxiliary intake cam phase θmsi is changed from 120 deg to 180 deg.
FIG. 17 is a view for explaining cam profiles of a main exhaust cam and a sub exhaust cam.
FIG. 18 is a diagram showing a valve lift curve and the like for explaining the operation of the exhaust valve when the sub exhaust cam phase θmse = 0 deg.
FIG. 19 is a view showing a valve lift curve and the like for explaining the operation of the exhaust valve when the sub exhaust cam phase θmse = 45 deg.
FIG. 20 is a diagram showing a valve lift curve and the like for explaining the operation of the exhaust valve when the sub exhaust cam phase θmse = 90 deg.
FIG. 21 is a view showing a valve lift curve and the like for explaining the operation of the exhaust valve when the sub exhaust cam phase θmse = 150 deg.
FIG. 22 is a block diagram showing a configuration for controlling a throttle valve mechanism, a sub intake cam phase variable mechanism, and an intake cam phase variable mechanism in the valve timing control device.
FIG. 23 is a block diagram showing a schematic configuration of a sub intake cam phase controller.
FIG. 24 is a diagram showing a calculation formula of a cylinder intake air amount Gcyl and a formula of a prediction algorithm of a state predictor in the first SPAS controller.
FIG. 25 is a diagram showing a mathematical expression of an identification algorithm of an onboard identifier in the first SPAS controller.
FIG. 26 is a diagram showing a mathematical expression of a sliding mode control algorithm of the sliding mode controller in the first SPAS controller.
FIG. 27 is a diagram showing a mathematical expression for describing a method of deriving Expression (19) in FIG. 26;
FIG. 28 is a diagram illustrating a phase plane and a switching line for explaining a sliding mode control algorithm.
FIG. 29 is a diagram illustrating an example of a convergence behavior of a tracking error Es when the switching function setting parameter Ss is changed in the sliding mode controller.
FIG. 30 is a block diagram illustrating a schematic configuration of a second SPAS controller.
FIG. 31 is a diagram showing a mathematical expression of a prediction algorithm of a state predictor in the second SPAS controller.
FIG. 32 is a diagram showing a formula of an identification algorithm of an onboard identifier in the second SPAS controller.
FIG. 33 is a diagram showing a mathematical expression of a sliding mode control algorithm of the sliding mode controller in the second SPAS controller.
FIG. 34 is a flowchart showing main control contents of an engine control process.
FIG. 35 is a flowchart showing a fuel control process.
FIG. 36 is a diagram showing an example of a map used for calculating a required drive torque TRQ_eng.
FIG. 37 is a flowchart showing a calculation process of a cylinder intake air amount Gcyl and a target intake air amount Gcyl_cmd.
FIG. 38 is a diagram showing an example of a map used for calculating a basic value Gcyl_cmd_base of a target intake air amount.
FIG. 39 is a diagram showing an example of a table used for calculating an air-fuel ratio correction coefficient Kgcyl_af.
FIG. 40 is a diagram showing an example of a table used for calculating a main fuel injection rate Rt_Pre.
FIG. 41 is a flowchart showing a supercharging pressure control process.
FIG. 42 is a diagram illustrating an example of a table used for calculating a basic value Dut_wg_base of a control input to the wastegate valve.
FIG. 43 is a diagram showing an example of a table used for calculating a target supercharging pressure Pc_cmd.
FIG. 44 is a flowchart showing intake valve control processing.
FIG. 45 is a flowchart showing a continuation of FIG. 44.
FIG. 46 is a diagram showing an example of a table used for calculating a catalyst warm-up value θmsi_cw of a target auxiliary intake cam phase.
FIG. 47 is a diagram illustrating an example of a table used for calculating a normal operation value θmi_drv of a target main intake cam phase.
FIG. 48 is a view showing an example of a map used for calculating a basic value θmsi_base of a target auxiliary intake cam phase.
FIG. 49 is a flowchart showing a throttle valve control process.
FIG. 50 is a diagram illustrating an example of a table used for calculating a catalyst warm-up value THcmd_ast of a target opening degree.
FIG. 51 is a diagram illustrating an example of a map used for calculating a normal operation value THcmd_drv of a target opening.
FIG. 52 is a diagram showing an example of a map used for calculating a failure value THcmd_fs of the target opening.
FIG. 53 is a diagram illustrating an operation example of engine control by the valve timing control device.
FIG. 54 is a block diagram showing a schematic configuration of a modified example of the valve timing control device;
[Explanation of symbols]
1 Valve timing control device
2 ECU (load detecting means, valve closing timing determining means, control means, valve lift determining means)
3 Internal combustion engine
6 Intake valve
20 Crank angle sensor (load detection means)
35 Accelerator opening sensor (load detection means)
40 Variable intake valve drive (variable valve timing device)
41 Main intake camshaft (first intake camshaft)
42 Sub intake camshaft (second intake camshaft)
43 Main intake cam (first intake cam)
44 Sub intake cam (second intake cam)
51 Intake rocker arm
51c pin (rotation fulcrum)
70 Variable auxiliary intake cam phase mechanism (variable intake cam phase mechanism)
221 first SPAS controller 221 (valve closing timing determining means)
θmsi Sub intake cam phase (relative phase between first and second intake camshafts)
θmsi_base Basic value of target auxiliary intake cam phase (value that determines closing timing of intake valve)
θmsiott Otto phase value (value corresponding to predetermined timing)
TRQ_eng Required drive torque (parameter representing load)
TRQott predetermined value (threshold value of predetermined first to third load regions)
Psd oil pressure

Claims (6)

A valve timing control device for an internal combustion engine that variably controls a valve closing timing with respect to a valve opening timing of an intake valve via a variable valve timing device,
Load detection means for detecting the load of the internal combustion engine,
Valve closing timing determining means for determining a valve closing timing of the intake valve according to the detected load of the internal combustion engine;
Control means for controlling the variable valve timing device according to the determined closing timing of the intake valve;
A valve timing control device for an internal combustion engine, comprising: When the load of the internal combustion engine is in a predetermined first load range, the valve closing timing determining means sets the valve closing timing of the intake valve to a predetermined value at which an expansion ratio during a combustion cycle of the internal combustion engine becomes equal to a compression ratio. When the load of the internal combustion engine is in a predetermined second load range higher than the predetermined first load range, the closing timing of the intake valve is set earlier than the predetermined timing. The valve timing control device for an internal combustion engine according to claim 1, wherein the timing is determined. The valve timing variable device is configured by a hydraulically driven valve timing variable device driven by supply of hydraulic pressure,
The valve timing control device for an internal combustion engine according to claim 1, wherein the control unit controls a hydraulic pressure supplied to the hydraulically driven variable valve timing device. 3. The valve timing control device for an internal combustion engine according to claim 1, wherein the variable valve timing device is configured to be capable of changing a valve lift amount of the intake valve. The valve timing variable device is configured to be capable of changing a valve lift amount of the intake valve,
When the load of the internal combustion engine is in a predetermined third load range lower than a predetermined load, the valve lift amount determining means for determining the valve lift amount of the intake valve to a value smaller than when the load is equal to or higher than the predetermined load is further provided. Prepare,
The valve closing timing determining means sets the valve closing timing of the intake valve such that an expansion ratio during a combustion cycle of the internal combustion engine becomes equal to a compression ratio when the load of the internal combustion engine is in the predetermined third load range. Determined earlier than the predetermined timing,
2. The valve timing control device for an internal combustion engine according to claim 1, wherein the control unit controls the variable valve timing device according to the determined valve closing timing and valve lift amount of the intake valve. 3. . The variable valve timing device,
An intake rocker arm that is rotatably supported at a pivot point and that opens and closes the intake valve by the rotation;
First and second intake camshafts rotating at the same rotational speed with each other;
A variable intake cam phase mechanism for changing a relative phase between the first and second intake camshafts;
A first intake cam provided on the first intake camshaft and rotating with the rotation of the first intake camshaft to rotate the intake rocker arm around the rotation fulcrum;
A second intake cam that is provided on the second intake camshaft and that rotates with the rotation of the second intake camshaft to move the rotation fulcrum of the intake rocker arm;
The valve timing control device for an internal combustion engine according to claim 4 or 5, further comprising:

Images