Electric valve timing control device and electric valve timing control method

Abstract

The electric valve timing control apparatus of the present application controls an electric valve timing apparatus which changes valve timing by changing a relative rotation phase of a camshaft with respect to a crankshaft of an internal combustion engine using a motor coupled to the camshaft, and includes a control section which, when changing the relative rotation phase of the camshaft using the electric valve timing apparatus after a stop process of the internal combustion engine, changes a phase changing method for changing the camshaft from a current phase to a target phase based on a relationship between the current phase and the target phase of the camshaft.

Description

TECHNICAL FIELD

[0001] The present application relates to an electric valve timing control apparatus and an electric valve timing control method that vary the valve timing (opening / closing timing) of an intake valve or an exhaust valve driven by a motor. BACKGROUND

[0002] In the related art, as a driving force transmission mechanism for synchronously rotating an intake camshaft or an exhaust camshaft with respect to a crankshaft that is an output shaft of an internal combustion engine, there are synchronous pulleys, sprockets, or gears. Further, there is known a variable valve timing apparatus that is assembled in them and adjusts the valve timing of an intake valve according to an operating state of an internal combustion engine.

[0003] In recent years, replacement from an oil pressure type valve timing apparatus to an electric type valve timing apparatus is progressing, and there is a tendency that a controllable temperature and a controllable engine speed increase. However, in the conventional electric valve timing apparatus, control at a low engine speed is difficult, and in particular, it is difficult to control the phase of an intake valve at an arbitrary timing at the time of engine stop of an automobile. In fact, a method of controlling the intake valve at a so-called default position of the electric valve timing apparatus and a mechanically reached position, and waiting for the next engine start is adopted.

[0004] The electric valve timing apparatus has a mechanism that varies the phase of a camshaft that drives an intake valve or an exhaust valve. The mechanism is configured such that an output from a motor of the electric valve timing apparatus is amplified by a reducer and transmitted to the camshaft. In a case where it is intended to start from an arbitrary valve timing at the next start (also referred to as startup) of an internal combustion engine, the phase of the camshaft can be shifted by energizing the motor after the stop of the internal combustion engine.

[0005] However, in a case where the electric valve timing apparatus is driven after the stop of the internal combustion engine, friction increases compared to a case where the electric valve timing apparatus is driven during the operation of the internal combustion engine. Therefore, in the driving of the electric valve timing apparatus after the stop, a large current is applied as an impact current of the motor at the start of the driving, and there is a concern that a large load is applied to a drive circuit and a wiring of the electric valve timing apparatus. Therefore, in the variation of the phase of the camshaft after the stop of the internal combustion engine, there is a problem that a method of suppressing the use of a current value must be adopted.

[0006] As a control method of the electric valve timing apparatus against such a problem, for example, there is a technology disclosed in Patent Literature 1. In the technology disclosed in Patent Literature 1, when the electric valve timing apparatus is operated during the stop of the internal combustion engine, a current that energizes the motor of the electric valve timing apparatus is increased compared to normal, and the electric valve timing apparatus can be easily operated even at the time of the stop of the internal combustion engine.

[0007] Further, in Patent Literature 2, when the electric valve timing device is operated at the time of stopping the internal combustion engine, a mode is adopted in which the camshaft is temporarily operated to the stop position of the decelerator, and thereafter, controlled to an arbitrary phase. Thereby, even in a region in which the signal from the cam angle sensor is interrupted, high-precision phase change operation of the camshaft can be performed.

[0008] Prior Art Documents

[0009] Patent Literature

[0010] Patent Literature 1: Japanese Patent Application Publication No. 2011-94581

[0011] Patent Literature 2: Japanese Patent Application Publication No. 2007-198314 SUMMARY

[0012] PROBLEMS TO BE SOLVED BY THE INVENTION

[0013] However, in Patent Literature 1, when the electric valve timing device is operated at the time of stopping the internal combustion engine, the energization amount of the motor is increased. Therefore, since the consumption amount of the current itself is deteriorated, there still remains a technical problem that the suppression of the current value cannot be achieved.

[0014] Further, in Patent Literature 2, once the stop position is passed, the electric valve timing device is caused to perform an invalid operation, and therefore, is not in harmony with the purpose of suppressing the current value.

[0015] In view of the above circumstances, it is desirable to achieve a technical solution in which the current of the motor can be suppressed and the electric valve timing device can be controlled to an arbitrary valve timing from the time of stopping the internal combustion engine until after the stopping.

[0016] TECHNICAL SOLUTION TO SOLVE THE PROBLEMS

[0017] To solve the above-described technical problem, an electric valve timing control device of one embodiment of the present application controls an electric valve timing device that changes a valve timing by changing a relative rotation phase of a camshaft with respect to a crankshaft of an internal combustion engine using a motor that is linked to the camshaft. The electric valve timing control device includes a control portion that, when changing the relative rotation phase of the camshaft using the electric valve timing device after a stop process of the internal combustion engine, changes a phase change method of changing the camshaft from a current phase to a target phase based on a relationship between the current phase and the target phase of the camshaft.

[0018] EFFECT OF THE INVENTION

[0019] According to at least one aspect of the present application, the current of the motor can be suppressed and the electric motor-driven valve timing apparatus can be controlled to an arbitrary valve timing from when the internal combustion engine is about to stop to after the internal combustion engine is stopped. Thus, the generation of excessive current can be prevented from causing overheating of the motor and the motor driver, and the phase of the valve (valves) can be controlled to an arbitrary phase from when the internal combustion engine is about to stop to after the internal combustion engine is stopped.

[0020] The technical problems, configurations and effects other than the above can be made more clear through the following description of the embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a schematic diagram showing a configuration example of an engine having an electric motor-driven valve timing apparatus.

[0022] Figure 2 is a side view showing a configuration example of the electric motor-driven valve timing apparatus.

[0023] Figure 3 is a cross-sectional view showing an example of a speed reducer in the electric motor-driven valve timing apparatus.

[0024] Figure 4 is a block diagram of a control system including an ECU to which the electric motor-driven valve timing apparatus is applied.

[0025] Figure 5 is a chart showing the definition of the action name for each engine state in the engine stop processing.

[0026] Figure 6 is a graph showing the profile curve of the intake valve in the case where the intake valve is set to the maximum advance (maximum advance angle) phase in the late-closing (delayed closing) Miller cycle of the first embodiment of the present application.

[0027] Figure 7 is a graph showing the profile curve of the intake valve in the case where the intake valve is set to the maximum retard (maximum retard angle) phase in the late-closing Miller cycle of the first embodiment of the present application.

[0028] Figure 8 is a schematic view showing the state in the cylinder of the engine when the engine cycle is operated in accordance with Figure 7 the intake profile curve.

[0029] Figure 9 is a graph showing the relationship between the angle and the rotational direction of the intake cam at the time of engine stop and the motor drive current.

[0030] Figure 10 is a block diagram showing an internal configuration example of the ECU of the first embodiment of the present application.

[0031] Figure 11An example of "single action" as a first phase change method after engine stop of the first embodiment of the application.

[0032] Figure 12 An example of "double action" as a second phase change method after engine stop of the first embodiment of the application.

[0033] Figure 13 A flowchart showing a sequence example of the electric valve timing control method of the first embodiment of the application.

[0034] Figure 14 A graph showing a profile curve of the intake valve in a case where the intake valve is set to the maximum advance phase in the early closing (early closing) Miller cycle of the second embodiment of the application.

[0035] Figure 15 A graph showing a profile curve of the intake valve in a case where the intake valve is set to the maximum retard phase in the early closing Miller cycle of the second embodiment of the application.

[0036] Figure 16 A flowchart showing a sequence example of the electric valve timing control method of the second embodiment of the application. DETAILED DESCRIPTION

[0037] Hereinafter, examples of modes for carrying out the application will be described with reference to the accompanying drawings. In the present specification and drawings, the same reference numerals are assigned to the same components having substantially the same functions or structures, and repeated descriptions will be omitted.

[0038] FIRST EMBODIMENT

[0039] First, the structure of an engine equipped with an electrically variable valve timing device will be described with reference to FIG. 1. In the present embodiment, an example in which an internal combustion engine is used as the engine will be described. Hereinafter, a case where the application is applied to a vehicle of a hybrid type having two powers of a traction motor and an engine will be described, but the application can also be applied to a vehicle having only the engine as the power. Figure 1 [Engine Structure]

[0040]

[0041] Figure 1 An example of the structure of an engine 50 having an electrically variable valve timing device is shown in FIG. 1. Figure 1 ​The illustrated engine 50 is configured as a naturally aspirated engine of a series 3-cylinder (three-cylinder in-line). In the engine 50, a combustion chamber is formed by the cylinder head 1 and the cylinder block 2, and the pistons 3 inserted in the cylinder block 2. The pistons 3 are linked to the crankshaft 5 via the connecting rods 4. A crank angle sensor 6 provided in the vicinity of the crankshaft 5 detects the rotational speed (engine speed) of the crankshaft 5.

[0042] The intake pipe 7 and the exhaust pipe 8 are each branched into two and connected toward the combustion chamber of one cylinder. Two intake valves 9 and two exhaust valves 10 are respectively provided to open and close the opening portions of the respective connecting portions of the combustion chamber and the intake pipe 7 and the exhaust pipe 8. An intake cam 11 is provided in the upper portion of the intake valve 9, and an exhaust cam 12 is provided in the upper portion of the exhaust valve 10. The intake valve 9 is opened and closed by the rotation of the intake cam 11, and the exhaust valve 10 is opened and closed by the rotation of the exhaust cam 12.

[0043] An intake cam pulley linked to the intake cam 11, an exhaust cam pulley linked to the exhaust cam 12, and a crank pulley linked to the crankshaft 5 are provided in the side portion of the engine 50, and are connected via a timing belt, which is not illustrated here. Thus, when the engine 50 is operated, the intake cam 11 and the exhaust cam 12 are rotated by the rotation of the crankshaft 5. The intake cam pulley and the exhaust cam pulley are set in such a manner that the intake cam 11 and the exhaust cam 12 are rotated one revolution during two revolutions of the crankshaft 5.

[0044] An electric valve timing device 27 capable of changing (varying) the phase of the intake cam 11 (intake valve 9) is provided in the intake cam 11 (see the electric valve timing device 27 described later Figure 2 ). In addition, an electric generator-motor is provided in the crankshaft 5 to operate as a generator during power generation, and to operate as a motor during the start (i.e., the startup) and the stop of the engine 50. The change in the angle of the intake cam 11, i.e., the rotational speed of the intake cam 11, is detected by an intake cam angle sensor 13 provided in the intake cam 11.

[0045] An injector 14 is provided on the intake side of the combustion chamber, and a spark plug 15 and an ignition coil 16 are provided in the upper portion of the combustion chamber. Fuel is stored in a fuel tank 17, and is delivered to a high-pressure fuel pump 19 via a fuel piping by a feed pump 18. The high-pressure fuel pump 19 is driven by the exhaust cam 12, and the fuel after pressure-boosting is delivered to a common rail 20. A fuel pressure sensor 21 is provided in the common rail 20, and can detect the fuel pressure (denoted as "fuel pressure"). The common rail 20 is connected to the injectors 14 provided in the respective cylinders via fuel piping.

[0046] A collector 7c having a larger diameter than the air flow path of the other portions is provided upstream of the intake pipe 7. The intake pipe 7 is connected to each cylinder from the collector 7c. In addition, a throttle valve (not shown) that can change the amount of air drawn into the cylinder is provided on the upstream side of the collector 7c.

[0047] A three-way catalyst 22 is provided on the downstream side of the exhaust pipe 8, and an oxygen sensor 23 is provided downstream thereof. A temperature sensor 24 that detects the temperature of the three-way catalyst 22 is provided on the three-way catalyst 22. A water temperature sensor 25 that measures the temperature of water that flows around the cylinder block 2 is provided on the cylinder block 2.

[0048] The signals of the water temperature, engine speed, and the like output from each sensor are input to an engine control unit (ECU: Engine Control Unit) 26. The ECU 26 controls the on / off of fuel injection and the phase of an electrically driven valve timing device 27 (camshaft, intake cam 11) on the basis of information obtained from these signals. Hereinafter, the electrically driven valve timing device will be sometimes referred to as VTC (Valve Timing Control).

[0049] [Structure and driving principle of electrically driven valve timing device]

[0050] Next, the structure and driving principle of the electrically driven valve timing device 27 will be described.

[0051] By inputting the rotational speed signals of the crankshaft 5, intake cam 11, and exhaust cam 12 detected by the crank angle sensor 6 and the intake cam angle sensor 13 to the ECU 26, the relative phase difference of the crankshaft 5 and the intake camshaft is calculated. In the structure of the engine 50 of the present embodiment, the crank angle sensor 6 detects a signal at every 6 deg. CA (Crank Angle), and the intake cam angle sensor 13 detects a signal at every 180 deg. CA.

[0052] Hereinafter, in the present specification, the relative rotational phase of the intake camshaft with respect to the crankshaft 5 will be referred to as "relative phase". In addition, there are cases where the relative phase with respect to the crankshaft 5 is described using the intake cam 11 instead of the intake camshaft.

[0053] Figure 2 is a side view showing an example of the structure of the electrically driven valve timing device 27.

[0054] Figure 3 is a cross-sectional view showing an example of the speed reducer 27a in the electrically driven valve timing device 27.

[0055] In Figure 2In the embodiment, the electric valve timing apparatus 27 is composed of a speed reducer 27a having a sprocket 27d, an electric motor 27b for driving the intake cam 11, and a UVW control unit 27c in this order from the intake cam 11 side. The sprocket 27d, the speed reducer 27a, and the electric motor 27b rotate by a common rotation shaft. Inside the UVW control unit 27c, a general-purpose IC 271 and a motor driver 272 are provided as an arithmetic unit for driving the electric motor. For the structure and operation of the UVW control unit 27c, reference is made to the description of the UVW control unit 27c described later. Figure 4 The description will be made.

[0056] Here, the method of changing the phase of the intake cam 11 and the crankshaft 5 based on the electric valve timing apparatus 27 will be described.

[0057] As shown in FIG. 2, the electric valve timing apparatus 27 is composed of a speed reducer 27a having a sprocket 27d, an electric motor 27b for driving the intake cam 11, and a UVW control unit 27c in this order from the intake cam 11 side. The sprocket 27d, the speed reducer 27a, and the electric motor 27b rotate by a common rotation shaft. Inside the UVW control unit 27c, a general-purpose IC 271 and a motor driver 272 are provided as an arithmetic unit for driving the electric motor. For the structure and operation of the UVW control unit 27c, reference is made to the description of the UVW control unit 27c described later. Figure 3 As shown in FIG. 3, the speed reducer 27a of the electric valve timing apparatus 27 is composed of a driving rotation body 28 having a recess 28a and a driven rotation body 29 having a protrusion 29a in the internal structure. The recess 28a is formed in a part of the outer periphery of the driving rotation body 28 along the circumferential direction, and the protrusion 29a is formed in a part of the inner periphery of the driven rotation body 29 along the circumferential direction. The recess 28a of the driving rotation body 28 is inserted into the protrusion 29a of the driven rotation body 29. The mechanism for physically determining the maximum advance position and the maximum retard position with respect to the above-described intake valve 9 is constituted by the end portion 28b or the end portion 28c of the recess 28a of the driving rotation body 28 butting against the end portion of the protrusion 29a of the driven rotation body 29. Figure 3 The respective arrows of (1) and (2) indicate the rotation direction of the driving rotation body 28 when the end portion 28b and the end portion 28c of the recess 28a butt against the protrusion 29a.

[0058] In Figure 3 (1), the end portion 28b of the recess 28a of the driving rotation body 28 is in abutment with the protrusion 29a of the driven rotation body 29, indicating that the intake cam 11 is in the maximum advance position. In Figure 3 (2), the end portion 28c of the recess 28a of the driving rotation body 28 is in abutment with the protrusion 29a of the driven rotation body 29, indicating that the intake cam 11 is in the maximum retard position.

[0059] With such a structure, the relative phase of the driving rotation body 28 and the driven rotation body 29 can be changed within the range of the physically maximum advance position (corresponding to the end portion 28b) and the maximum retard position (corresponding to the end portion 28c). Also, by making the relative phase of the driving rotation body 28 and the driven rotation body 29 deviate, the relative phase of the intake cam 11 supported by the intake camshaft connected to the driving rotation body 28 and the crankshaft 5 connected to the driven rotation body 29 via the timing belt is changed.

[0060] [Control system including ECU]

[0061] Next, with respect to the control system including the ECU 26, reference is made to Figure 4 for an explanation.

[0062] Figure 4 is a block diagram showing the control system including the ECU 26 to which the electric valve timing apparatus 27 is applied. With reference to Figure 4 , the path by which the ECU 26 acquires the actual rotational speed and rotational direction of the motor 27b of the electric valve timing apparatus 27 is explained.

[0063] First, the Hall IC circuit (an example of a motor sensor) provided in the general-purpose IC 271 of the UVW control unit 27c detects a Hall voltage generated by the rotation of the motor (the "VTC motor" in the figure) 27b of the electric valve timing apparatus 27. Also, the general-purpose IC 271 acquires a Hall IC signal (a digital output) corresponding to the Hall voltage from the Hall IC circuit. The general-purpose IC 271 converts the Hall IC signal into the rotational speed and rotational direction of the motor 27b and outputs them to the ECU 26, whereby the ECU 26 acquires the rotational speed and rotational direction of the motor 27b.

[0064] Further, the optimum phase of the intake cam 11 is calculated step by step to control the phase of the intake cam 11 at an appropriate phase. Then, the ECU 26 calculates an appropriate valve timing in accordance with the required engine rotational speed and required engine torque on the basis of the calculation result of the actual phase of the intake cam 11. The ECU 26 converts the calculated appropriate valve timing into the target rotational direction and target rotational speed of the motor 27b of the electric valve timing apparatus 27 and sends it to the UVW control unit 27c of the electric valve timing apparatus 27 as a PWM signal based on duty control.

[0065] In the UVW control unit 27c, the target rotational speed and target rotational direction of the motor 27b are received by the general-purpose IC 271 via a target motor speed reception section not shown. In the general-purpose IC 271, the actual rotational speed and actual rotational direction of the motor 27b of the electric valve timing apparatus 27 are acquired, feedback control is implemented in accordance with the signals of the target rotational direction and target rotational speed of the motor 27b, and then a control signal is sent to the motor driver 272 so as to become an appropriate motor rotational speed. The motor driver 272 converts this control signal into a three-phase AC signal of UVW using the supply power from the battery and outputs it to the motor 27b as a UVW drive signal, whereby the motor 27b is driven.

[0066] If the crankshaft 5 and the intake camshaft do not rotate by more than a certain angle, the crank angle sensor 6 and the intake cam angle sensor 13 cannot detect the respective rotations. Therefore, the rotation of the motor 27b is detected by the Hall IC circuit, and based on the detection result, the command value to the UVW control unit 27c is interpolated in the ECU 26.

[0067] In the general-purpose IC 271 of the present embodiment, the command signals of the rotation direction and the rotational speed of the motor 27b received from the ECU 26 adopt the following specifications. The rotation in the same direction as the rotation direction of the camshaft is taken as positive rotation, and the rotation in the opposite direction is taken as reverse rotation, and the positive rotation / reverse rotation is distinguished according to the frequency of the input PWM. The frequency of the PWM is 400 Hz in the positive rotation, and the frequency of the PWM is 200 Hz in the reverse rotation.

[0068] Generally, the ratio of (the rotational speed of the crankshaft 5) : (the rotational speed of the intake cam 11) is 2: 1. In order to change the phase of the intake cam 11 with respect to the crankshaft 5 by the electric valve timing apparatus 27, it is necessary to control so that the rotational speed of the intake cam 11 is higher or lower than 1 / 2 times the rotational speed of the crankshaft 5. The rotational speed of the camshaft is instantaneously increased to control the phase of the intake valve 9 or the exhaust valve 10 in the direction of early opening and early closing in the engine cycle, which is called advance control. On the other hand, the rotational speed of the camshaft is instantaneously decreased to control the phase of the intake valve 9 or the exhaust valve 10 in the direction of late opening and late closing in the engine cycle, which is called retard control.

[0069] Among the types of engines in which the Miller cycle is implemented by mounting the electric valve timing apparatus 27, there are a late-closing Miller cycle (refer to the late-closing Miller cycle described later Figure 6 and Figure 7 ), and an early-closing Miller cycle (refer to the early-closing Miller cycle described later Figure 14 and Figure 15 ). In the present embodiment, an engine of the type capable of the late-closing Miller cycle is assumed to be mounted with the electric valve timing apparatus 27 on the intake cam 11. The "late-closing Miller cycle" refers to an engine cycle in which the intake valve 9 is closed after the piston 3 reaches the bottom dead center in the compression stroke of a four-stroke engine. The engine 50 adopted in the present embodiment can make the late-closing Miller cycle stand by making the intake cam 11 change the phase to the retard side using the mounted electric valve timing apparatus 27.

[0070] [Electric valve timing operation sequence and effects at engine stop]

[0071] Next, the operation sequence at engine stop is described based on the phase change driving principle of the electric valve timing apparatus 27. Here, in the present embodiment, the engine 50 is assumed to be mounted with the electric valve timing apparatus 27 on the intake cam 11, and the engine 50 is assumed to be capable of the late-closing Miller cycle. Figure 5The definition in the text represents the action name for each time sequence in the engine stopping sequence, from when the engine is running at low speed until it stops.

[0072] Figure 5 This is a graph representing the defined action names for each engine state during engine stop processing. The horizontal axis represents time [sec], and the vertical axis represents engine speed [rpm].

[0073] The period from receiving the engine stop request from ECU26 and the fuel injector 14 stopping fuel injection until the engine speed reaches zero is defined as "engine stop processing". The period before engine stop processing during engine operation is defined as "engine operation". The period after the engine stop processing period, when the engine speed reaches zero, is defined as "after engine stop".

[0074] The required action of the electric valve timing device 27 when the engine stops is to control the phase of the intake valve 9 (intake cam 11) of the engine 50 so that it is in the maximum lag position before the engine stops. Figure 3 (2)) and keep the phase unchanged to stop the engine 50. If the phase of the intake valve 9 can be kept at the maximum lag position after the engine stops by phase control when the engine stops, the phase of the intake valve 9 can be restarted from the maximum lag position when the engine is restarted again.

[0075] As a result, the valve timing of intake valve 9 is controlled at the maximum lag position ( Figure 3 The effect of restarting the engine 50 in the state of (2) can be explained by the reduction in the intake airflow into the cylinder during the motoring (using a motor to rotate the output shaft) that increases the rotational speed by the generator before the initial detonation. By reducing the intake airflow, the airflow during the compression stroke is reduced, thus reducing pumping loss. Suppressing pumping loss during motoring reduces the load on the piston 3 caused by its up-and-down movement, suppressing speed fluctuations that cause the engine speed to rise. Ultimately, by suppressing these engine speed fluctuations, vibrations during engine restart can be reduced. Therefore, it is required in this embodiment that the phase of the intake valve 9 is at its maximum lag position during engine restart.

[0076] [The relationship between the phase of the intake and exhaust valves and the lift in a delayed Miller cycle]

[0077] Next, the relationship between the phase of the intake and exhaust valves and the rise in the aforementioned delayed-closing Miller cycle will be explained.

[0078] Figure 6 This represents the profile curve 9a of the intake valve 9 when the intake valve 9 is set to the maximum advance phase in the late-closing Miller cycle.

[0079] Figure 7 This refers to the profile curve 9b of the intake valve 9 when the intake valve 9 is set to the maximum lag phase in the delayed Miller cycle.

[0080] exist Figure 6 and Figure 7 The horizontal axis represents the change of engine stroke in the order of expansion stroke, exhaust stroke, intake stroke, and compression stroke, while the vertical axis represents the rise of intake valve 9 and exhaust valve 10 [mm].

[0081] Figure 6 and Figure 7 The outline curves of the intake valve 9 and exhaust valve 10 shown represent the opening and closing times of the intake valve 9 and exhaust valve 10, and the amount of rise in each engine stroke. Figure 6 In the late-closing Miller cycle, profile curve 9a represents the changes in the opening and closing timing (timing) and rise of the intake valve 9 at its maximum advance, and profile curve 9b represents the changes in the opening and closing timing and rise of the intake valve 9 at its maximum lag. Additionally, profile curve 10a represents the changes in the opening and closing timing and rise of the exhaust valve 10 in the late-closing Miller cycle. In the late-closing Miller cycle, the intake valve 9 closes after the piston 3 reaches bottom dead center (BDC) during the compression stroke of a four-stroke engine.

[0082] Profile curve 9b represents the position where the intake valve 9 is physically at its maximum lag in the reducer 27a. Figure 3 The engine cycles under the condition of (2)). The objective of this embodiment is to... Figure 7 In the profile curve 9b of the intake valve 9, that is, the engine 50 is restarted with the valve timing of the intake valve 9 extremely delayed to the maximum advance position. In this embodiment, the action angles of the intake cam 11 (intake camshaft) and the exhaust cam 12 (exhaust camshaft) are 240°CA. When the intake cam 11 is in the phase of maximum delay, the phase of the intake valve 9 is delayed to IVC (Intake Valve Close) 140°CA_ABDC (the valve timing when the intake valve 9 closes 140° after the bottom dead center of the crankshaft 5).

[0083] Here, regarding Figure 7 The profile curve 9b of the intake cam 11 shown represents the state of the engine cylinders during engine cycle, with reference to... Figure 8Please provide an explanation.

[0084] Figure 8 It means according to Figure 7 The profile curve 9b of the intake cam 11 is a schematic diagram of the state inside the engine cylinder during engine cycle, indicating that the intake valve 9 is controlled to the maximum lag position. Figure 3 Examples of the state of the engine cylinder (intake valve 9, exhaust valve 10) during each stroke of the engine cycle (2).

[0085] exist Figure 8 The upper side indicates and Figure 7 The same contour curves 9b and 10a.

[0086] exist Figure 8 The lower side, at each moment (1) to (4), shows the movement of the intake valve 9 and exhaust valve 10 as defined by the profile curves 9b and 10a. Let Figure 8 In the schematic diagram of the intake pipe 7, exhaust pipe 8, and combustion chamber shown on the lower side, the pipe on the left is the intake pipe 7, and the pipe on the right is the exhaust pipe 8. In addition, at times (1) to (4), the thicker area represents the fresh air from the intake pipe 7, and the thinner area represents the exhaust from the exhaust pipe 8.

[0087] (1) At the bottom dead center (BDC) before the exhaust stroke, only exhaust valve 10 is open.

[0088] (2) From the exhaust stroke to IVO (Intake Valve Open) 80deg.CA_ATDC, both intake valve 9 and exhaust valve 10 are closed (the combustion chamber is under negative pressure).

[0089] (3) After the intake stroke begins, the exhaust valve 10 closes at the bottom dead center, and only the intake valve 9 is open.

[0090] (4) During the intake stroke, the piston position decreases and the intake valve 9 closes at IVC140deg.CA_ABDC. In the subsequent compression stroke, it becomes pressurized, and the actual intake volume is 40deg.CA from top dead center.

[0091] In this way, by controlling the phase of the intake valve 9 to IVC140deg.CA_ABDC to start the engine 50, the compression load applied to the piston 3 during the compression stroke can be reduced to about 1 / 3 compared to the existing engine start (IVC60deg.CA_ABDC).

[0092] [Methods for Electric Valve Timing Control and Phase Calculation After Engine Stoppage]

[0093] Such as using Figure 4-8As explained, the phase of the intake cam 11 with respect to the rotation of the crankshaft 5 is calculated substantially based on the signals of the crank angle sensor 6 and the intake cam angle sensor 13 acquired by the ECU 26. In the vehicle equipped with the electric valve timing apparatus 27 of the present embodiment, the frequency of acquiring the signal of the intake cam angle sensor 13 is every 180 deg.CA, and the accuracy is low. Therefore, during the period until the next signal is acquired from the intake cam angle sensor 13, the angle of the intake cam 11 is interpolated based on the signal from the Hall IC circuit of the motor 27b incorporated in the electric valve timing apparatus 27.

[0094] Also, in the case where the motor 27b of the electric valve timing apparatus 27 is driven to change the phase of the intake valve 9 with respect to the crankshaft 5, the speed is reduced in correspondence with the amount of reduction of the reduction ratio of the reduction gear 27a incorporated in the electric valve timing apparatus 27. Therefore, the phase of the intake cam 11 can be calculated by the ECU 26 with higher accuracy. In the case where the engine speed is a certain value or more, the phase of the intake cam 11 can be calculated without problems by the above-described method, but it is difficult to calculate by the above-described method in the engine immediately before the engine is stopped with a lowered engine speed or immediately after the engine is restarted. For example, since the teeth of the crank plate are 6 deg, the rotation of the crankshaft 5 can be detected only every 6 deg by the crank angle sensor 6. Also, the rotation of the intake camshaft can be detected only every 180 deg.CA by the intake cam angle sensor 13. Thus, in the engine low speed rotation region, the number of detection signals input with respect to time is small, and since the interval of the detection signals becomes large, the detection accuracy of the phase of the intake cam 11 is reduced.

[0095] As described above, the phase of the intake valve 9 in the engine operation is calculated substantially by the crank angle sensor 6 and the intake cam angle sensor 13, and is supplemented (interpolated) based on the rotation speed of the motor 27b between the sensor signals. The relative value with respect to the crankshaft 5 is calculated using these three kinds of signals. However, as for the change in the phase of the intake cam 11 after the engine is stopped, the signals of the crank angle sensor 6 and the intake cam angle sensor 13 are not output. Therefore, after the engine is stopped, the phase control is performed substantially by the ECU 26 by monitoring only the rotation speed of the motor 27b in the electric valve timing apparatus 27.

[0096] Further, at the time of engine stop, the cam lobe 11m (refer to Figure 9) or the influence of crank reverse rotation immediately after the engine stops, there is a certain probability that the phenomenon of the phase of the intake valve 9 controlled to the maximum retardation deviating to the advance side. In order to satisfy the above-mentioned operation requirement at the time of engine restart, it is required to change the phase of the intake valve 9 after the engine stops and newly control to the maximum retardation. With respect to the unexpected phase change caused by the above-mentioned disturbance after the engine stops, the amount of phase change of the intake valve 9 can be calculated from the rotational speed of the motor 27b in the electric valve timing apparatus 27.

[0097] In the present application, the amount of unexpected phase change of the intake valve 9 after the engine stops can be acquired by the ECU 26, and the amount of phase change having occurred is intentionally changed to the phase of the maximum retardation (hereinafter "target phase") immediately after the engine stops. At this time, since it is at the time of engine stop, the phase change of the intake valve 9 is performed in a state of large friction.

[0098] [VTC angle and motor drive current]

[0099] Here, with respect to the relationship between the phase of the electric valve timing apparatus 27 (angle of the intake cam 11) and the drive current flowing in the motor 27b for driving the intake valve 9, description will be made with reference to Figure 9

[0100] Figure 9 indicates the relationship between the angle of the intake cam 11 at the time of engine stop, the direction of rotation, and the motor drive current. In the upper layer of Figure 9 , the structure in which the intake cam 11 abuts against the valve spring via the contact piece 90 is schematically indicated. The intake cam 11 is an eccentric cam having an egg-shaped cross section. The intake valve 9 is provided at the front end of the valve spring as a driven member. In addition, in the upper layer of Figure 9 , the angle of the intake cam 11 (VTC angle in the figure) at the time of engine stop, and the direction of engine rotation are indicated. In the middle layer of Figure 9 , the time change in the angle [deg.CA] of the intake cam 11 in the case where the intake cam 11 is rotated from the advance side to the retardation side (counterclockwise) is indicated. In the lower layer of Figure 9 , the time change in the drive current [A] of the motor 27b is indicated. Figure 9 The left side of Figure 9 is an example of operation in which the intake cam 11 does not pass over the cam lobe (cam convex portion) 11m on the major diameter, and the right side of is an example of operation in which the intake cam 11 passes over the cam lobe 11m on the major diameter. The operation of passing over the cam lobe 11m refers to the operation in which the contact piece 90 rides up the cam lobe 11m of the intake cam 11 and comes down from the cam lobe 11m by one phase change, and can also be said to be the operation (compression operation) in which the intake cam 11 presses the valve spring by the contact piece 90.

[0101] When the electric valve timing apparatus 27 is operated in the engine stop, an excessive rotational torque is required compared to the engine rotation. Particularly, depending on the relationship between the stop position of the crankshaft 5 of the engine 50 and the phase of the intake camshaft (intake cam 11), when the phase of the intake cam 11 is changed over the cam lobe 11m to change the electric valve timing apparatus 27, an excessive current is applied to the motor 27b and the motor driver 272. From the viewpoint of heat generation of the circuit and the failure durability of the circuit, generation of a large current is required to be suppressed.

[0102] On the left side of Figure 9 , when the phase of the intake cam 11 is changed to the retard side, since the intake cam 11 does not pass over the cam lobe 11m, the drive current of the motor 27b is lower than the target current (for example, the peak current is 20 A or less) indicated by the broken line. However, on the right side of Figure 9 , when the phase of the intake cam 11 is changed to the retard side, since the intake cam 11 passes over the cam lobe 11m, the drive current of the motor 27b greatly exceeds the target current. Particularly, a larger current is generated when the intake cam 11 starts to act.

[0103] Therefore, the present application, depending on the phase of the intake cam 11 after the engine stop and the phase change direction (rotation direction) of the intake cam 11, implements the phase change of the intake cam 11 by a method of switching from the normal phase change control (refer to Figure 11 ) to the special phase change control (refer to Figure 12 ).

[0104] [Internal structure of ECU]

[0105] Next, the internal structure and operation of the ECU 26 that implements the valve timing control will be described with reference to Figure 10 .

[0106] Figure 10 is a block diagram showing an example of the internal structure of the ECU 26. The ECU 26 (an example of an electric valve timing control apparatus) controls the engine 50 having an electric valve timing apparatus (VTC) 27 capable of changing the phase of the intake valve 9. The ECU 26 implements the electric valve timing control method of the present embodiment, and controls the engine 50 having the electric valve timing apparatus 27.

[0107] The ECU 26 includes a CPU (Central Processing Unit) 30, a RAM (Random Access Memory) 31, and a ROM (Read Only Memory) 32.

[0108] The ECU 26 is inputted with, for example, a primary voltage detected by a voltage sensor (not shown) of the ignition coil 16, a secondary current detected by a current sensor (not shown) of the ignition coil 16, accelerator depression information (accelerator opening degree) detected by an accelerator opening degree sensor (not shown), angle information (crank angle, intake cam angle) detected by the crank angle sensor 6 and the intake cam angle sensor 13, a rotation speed of the engine 50, a throttle opening degree from a throttle valve (not shown), a battery voltage (battery capacity) detected by a battery voltage sensor (not shown), and the like.

[0109] The input information of each sensor inputted to the ECU 26 is temporarily stored in the RAM 31, and is subjected to arithmetic processing by the CPU 30 according to a prescribed control program. Variables, parameters, and the like generated in the middle of the arithmetic processing by the CPU 30 are temporarily written in the RAM 31, and are appropriately read by the CPU 30. However, instead of the CPU 30, an MPU (Micro Processing Unit) can be used.

[0110] The ROM 32 permanently records programs, data, and the like necessary for the operation of the CPU 30, and is used as an example of a computer-readable non-transitory recording medium in which programs executed by the ECU 26 are stored. Therefore, a control program describing the contents of the arithmetic processing by the CPU 30 is written in the ROM 32 in advance, and is executed by being appropriately read by the CPU 30. In addition, for example, map information 321 for selection of the phase change method is stored in the ROM 32. However, a structure in which the map information 321 is stored in a non-volatile storage portion provided in the ECU 26 via a network can also be employed.

[0111] As described above, each of the functions of the engine state judging portion 301, the valve phase detecting portion 302, the phase change method selecting portion 303, and the valve phase changing portion 304 shown in the drawing is realized by the control program executed by the CPU 30. Thereby, the CPU 30 controls the electric valve timing apparatus 27 which changes the valve timing by changing the relative rotation phase of the intake camshaft with respect to the crankshaft 5 of the engine 50 by the motor 27b coupled to the intake camshaft.

[0112] The engine state judging portion 301 judges the state of the engine 50, that is, whether the engine 50 is stopped, and outputs the result of the judgment to the valve phase detecting portion 302.

[0113] The valve phase detecting portion 302 detects the relative rotation phase of the intake valve 9, that is, the intake camshaft (intake cam 11) with respect to the crankshaft 5 in the case where the engine 50 is judged to be stopped by the engine state judging portion 301.

[0114] The phase change method selection section 303 selects a method of changing the relative rotational phase of the intake camshaft from the current phase to the target phase based on the relationship between the current phase and the target phase of the camshaft when the relative rotational phase of the intake camshaft is changed by the electric valve timing apparatus 27 after the engine 50 is stopped. More specifically, the first phase change method and the second phase change method are switched based on the relationship between the current phase and the target phase of the intake camshaft described in the map information 321 when the relative rotational phase of the intake camshaft is changed by the electric valve timing apparatus 27 after the engine 50 is stopped.

[0115] For example, in the map information 321, the current phase of the intake camshaft is set on the first axis, the target phase of the intake camshaft is set on the second axis, and the phase change method is defined at the intersection of the first axis and the second axis. The phase change method selection section 303 switches the phase change method with reference to the map information 321.

[0116] The first phase change method (hereinafter referred to as "single action") is a method of rotating the intake camshaft in a first direction that approaches the target phase from the current phase when the relative rotational phase of the intake camshaft is changed, and changing the intake camshaft to the target phase. The second phase change method (hereinafter referred to as "double action") is a method of rotating the intake camshaft in a second direction that is away from the target phase by a prescribed phase amount by a first action, and then rotating the intake camshaft in the first direction by a second action to change the intake camshaft to the target phase. In the case where the second phase change method is selected, the prescribed phase amount that is rotated by the first action is a value read from the ROM 32. The prescribed phase amount can be constant, or can be set for each combination of the current phase and the target phase. Details of the first phase change method and the second phase change method are described in detail in Figure 11 and Figure 12 Details are described later.

[0117] The valve phase change section 304 changes the intake camshaft from the current phase to the target phase in accordance with the phase change method selected by the phase change method selection section 303.

[0118] Further, in the present embodiment, a structure is adopted in which the engine state determination section 301, the valve phase detection section 302, the phase change method selection section 303, the valve phase change section 304, and the map information 321 are provided in the ECU 26, but the structure is not limited to this. For example, a part or all of the engine state determination section 301, the valve phase detection section 302, the phase change method selection section 303, the valve phase change section 304, and the map information 321 can be installed in another device different from the ECU 26.

[0119] [Phase change control method after engine stop]

[0120] (first phase change method)

[0121] Figure 11 An example of the first phase change method after engine stop, i.e., "single operation", in the first embodiment is shown. In this example, an operation mode in which, when the phase of the intake cam 11 is changed after engine stop, the direction in which the intake cam 11 should be operated (in this case, the maximum retardation direction) is the side in which the current of the motor 27b is smaller is shown. This operation mode is an example of the normal phase change control in which the phase change is completed by one rotation operation.

[0122] In Figure 11 the upper side, the relationship of the intake cam 11, the contact piece 90, and the valve spring, and the lift amount of the intake valve 9 are shown. Figure 11 The horizontal axis shows how the engine stroke changes in the order of expansion stroke, exhaust stroke, intake stroke, and compression stroke, and the vertical axis shows the lift amount [mm] of the intake valve 9.

[0123] An example in which the phase of the intake camshaft is shifted from the maximum retardation stop position 110 to the advanced position 100 on the advanced side due to an unexpected advanced operation after the engine 50 is stopped (phase shift) is assumed. At this time, the valve phase detection section 302 calculates the relative value of the phase of the crankshaft 5 and the intake camshaft (relative positional relationship) from the crank angle sensor 6 calculated at intervals of 6 deg. CA and the rotational speed of the motor 27b in the electric valve timing device 27, and calculates the relative value of the contact piece 90 and the cam lobe 11m of the intake cam 11 at this time.

[0124] In Figure 11 the example shown, it can be confirmed that the phase of the intake cam 11 is changed from the maximum retardation stop position 110 (profile curve 9b) to the advanced position 100 (profile curve 9c) on the advanced side. According to the calculation results described above, in the case where the intake cam 11 is controlled in the direction in which it falls from the cam lobe 11m, i.e., the retardation direction, from the position 100, a large current value is not generated. Therefore, when the intake cam 11 is controlled again to the maximum retardation stop position 110, an instruction for driving the intake cam 11 in the retardation direction (direction close to the maximum retardation stop position 110) is output from the ECU 26 to the electric valve timing device 27, and thus the control in the maximum retardation direction after engine stop can be achieved.

[0125] (second phase change method)

[0126] Figure 12An example of the second phase change method, i.e., "double action", after engine stop in the first embodiment is shown. In this example, when the phase of the intake cam 11 is changed after engine stop, the direction in which the intake cam 11 should act (here, the maximum retardation direction) is the action mode in the case where the current of the motor 27b exceeds the target current on the larger side. This action mode is an example of a special phase change control in which the phase change is completed by secondary rotation action.

[0127] In Figure 12 , it is shown that, although the engine is stopped with the phase of the intake cam 11 at the maximum retardation stop position 110 (profile curve 9b), the phase of the intake cam 11 shifts to the position 101 (profile curve 9d) in the advance direction due to subsequent disturbance. In this case as well, as explained in Figure 11 , the intake cam 11 is driven in the retardation direction (the maximum retardation stop position 110), and the relative positional relationship of the contact piece 90 and the cam lobe 11m is calculated.

[0128] As a result, as shown in the position 101 (profile curve 9d), when the intake cam 11 is rotated in the retardation direction, in the case where the cam lobe 11m and the contact piece 90 abut, an action of temporarily advancing the intake cam 11 to the position 120 (profile curve 9e) away from the maximum retardation stop position 110 (arrow 121) is implemented. Subsequently, an action of retarding from the position 120 where the influence of the cam lobe 11m is small to the maximum retardation stop position 110 (profile curve 9b) (arrow 122) is implemented. The second phase change method can also be said to use the reaction of the first action in the opposite phase direction in the second action.

[0129] Thus, the maximum torque when the electric motor valve timing device 27 is driven can be reduced. That is, the impact current of the motor 27b at the time of phase change control can be suppressed. Therefore, in the case where the direction in which the cam lobe 11m is mounted coincides with the direction (here, the retardation direction) of the region where the target phase exists, when the intake cam 11 is controlled in the advance direction, a large current value is not generated.

[0130] That is, when the intake cam 11 is controlled again to the maximum retardation stop position 110, the electric motor valve timing device 27 is instructed from the ECU 26 to temporarily drive the intake cam 11 in the advance direction (the direction away from the maximum retardation stop position 110), and rotated to an arbitrary position (the relative position of the contact piece 90 and the cam lobe 11m in which the impact current value can be suppressed). Subsequently, the intake cam 11 is instructed to be driven in the retardation direction (the direction close to the maximum retardation stop position 110), and thus control in the maximum retardation direction after engine stop can be achieved.

[0131] In the operation in which the intake cam 11 (intake camshaft) is changed by the prescribed phase amount in the direction away from the target phase (second direction) indicated by the arrow 121, the prescribed phase amount can be set within a range in which the apex of the cam lobe 11m does not abut against the contact piece 90. For example, as the prescribed phase amount, a value in which the contact piece 90 reaches the middle of the cam lobe 11m of the intake cam 11 when the current of the motor 27b does not exceed the target current within a range in which the intake cam 11 is rotated in the direction away from the target phase can be set. The prescribed phase amount of the first operation in the second phase changing method is obtained in advance by experiment or calculation and stored in the ROM 32 (map information 321).

[0132] [Electrically controlled valve timing control method]

[0133] Next, the electrically controlled valve timing control method in the first embodiment will be described with reference to Figure 13 the flowchart shown in FIG. 10.

[0134] Figure 13 is a flowchart showing a sequence example of the electrically controlled valve timing control method of the first embodiment. The sequence shown in this flowchart is realized by the CPU 30 reading and executing the control program recorded in the ROM 32. Here, as the requirement of the phase control at the next engine start, the series of operations from when the engine is stopped to when the phase of the intake valve 9 is changed to the maximum lag position at the next engine start is shown. Hereinafter, the flowchart shown in FIG. 10 will be described for each processing step. In this flowchart, the engine operation is set as the start condition, and the time when the engine is stopped and the next engine start flag becomes ON (on) is set as the control end condition. Figure 13

[0135] <Step S1>

[0136] In the control of the electrically controlled valve timing device 27 in the engine operation, as described above, the CPU 30 in the ECU 26 calculates the PWM signal in which the duty ratio proportional to the engine speed is calculated based on the signal from the crank angle sensor 6 as the normal control. The CPU 30 outputs this PWM signal to the general-purpose IC 271 of the UVW control unit 27c.

[0137] <Step S2>

[0138] The engine state judging section 301 of the CPU 30 confirms the battery (refer to FIG. 1) (Step S2). When the battery is determined to be in the normal state, the CPU 30 proceeds to Step S3. When the battery is determined to be in the abnormal state, the CPU 30 proceeds to Step S4. Figure 4 ​) is reached. When the battery charge capacity has not reached the upper limit value (NO in S2), the engine state judging section 301 returns to step Sl to continue the normal control. The ECU 26 does not stop the engine 50 even if the vehicle stops due to a signal, traffic congestion, or the like, as long as the key is not off. In the case where the key is off, the CPU 30 ends the processing of the present flowchart. Further, as other engine stop conditions, there can be cited an idle stop, air conditioning device use, catalyst temperature reaching a threshold value, and the like.

[0139] Step S3

[0140] The engine state judging section 301 of the CPU 30 judges in the ECU 26 whether the fuel cut command is ON, and when the fuel cut command is ON, moves to step S4 (YES in S3), and when the fuel cut command is OFF, returns to step Sl to continue the normal control (NO in S3). The ECU 26 goes through a process of moving to the fuel cut operation of stopping the fuel injection before stopping the engine 50. At this time, since the engine torque is not needed, the engine 50 enters the fuel cut operation mode, and the fuel injection signal from the CPU 30 to the injector 14 is OFF (turned off), and the supply of fuel to the combustion chamber is stopped. During the fuel cut operation after the fuel cut (in the engine stop processing of the CPU 30), the engine 50 rotates by inertia, and finally the engine speed becomes zero. Therefore, the stop of the fuel injection is confirmed as one of the flags for judging the engine stop. Figure 3

[0141] Step S4

[0142] The valve phase changing section 304 of the CPU 30 controls the electrically driven valve timing device 27 at the same time as the start of the fuel cut to cause the phase of the intake valve 9 to lag (S4). The target phase of the intake valve 9 after the fuel cut is the maximum lag position (the end portion 28c of the driving rotary body 28, the outline curve 9b of the intake valve 9). The completion of the change of the phase to the maximum lag position is confirmed as one of the flags for judging the engine stop. Figure 7

[0143] Step S5

[0144] ​​Further, the CPU 30's valve phase detection section 302 judges whether the phase of the intake valve 9 is maximum lag, and shifts to step S6 when the phase of the intake valve 9 is maximum lag ("Yes" of S5). When the phase of the intake valve 9 is not maximum lag ("No" of S5), the CPU 30's valve phase changing section 304 returns to step S4 to control the phase of the intake valve 9 to maximum lag again. In a case where the engine 50 is being driven in a state where the intake valve 9 is controlled to maximum lag by the electric valve timing apparatus 27, the Hall voltage (Hall IC signal) from the motor 27b of the electric valve timing apparatus 27 is output only when rotated in the advance direction. Therefore, the Hall voltage from the motor 27b of the electric valve timing apparatus 27 is not in the advance direction item, but also serves as one of the flags for judging engine stop.

[0145] <Step S6>

[0146] The CPU 30's engine state judging section 301 judges engine stop through the "Yes" judgment of step S5. In the present embodiment, the condition for judging engine stop is the AND condition (logical product) of four items that the fuel injection signal from the CPU 30 to the injector 14 becomes OFF ("Yes" of S3), the pulse signal from the crank angle sensor 6 is not input to the CPU 30, the phase of the intake valve 9 is controlled to maximum lag (S4, S5), and the pulse signal in the advance direction of the motor sensor in the electric valve timing apparatus 27 is not input to the CPU 30. Among them, the AND condition of the four items is an example, and for example, a combination of one or more items can also be used.

[0147] <Step S7>

[0148] The judgment of engine stop shown in the above step S6 is input to step S7 as a condition. In step S7, a continuation condition of the loop processing from step S8 to step S17 is indicated. The end condition of the loop processing is the time when the engine start judgment flag from the ECU 26 becomes ON next time. That is, the CPU 30's engine state judging section 301 always executes the present loop processing in a state where the motor 27b is energized and the engine 50 is stopped.

[0149] <Step S8>

[0150] After entering the above-described step S7, the CPU 30's valve phase detection section 302 monitors the rotational speed of the motor 27b in the electric valve timing device 27 and the signals of the crank angle sensor 6 and the intake cam angle sensor 13 during the engine 50 is stopped. The valve phase detection section 302 calculates the relative phase of the phase of the intake valve 9 and the phase of the crankshaft 5 at the time of engine stop. In the following, each mode regarding the unexpected phase change of the intake valve 9 at this time is described.

[0151] (Scene A)

[0152] This item is a case where, after the engine 50 is temporarily stopped, the engine start flag is not established, the rotation (pulse signal) is detected by the crank angle sensor 6, and the rotation (pulse signal) of the motor 27b in the advance direction is detected by the motor sensor (Hall IC circuit) in the electric valve timing device 27. At this time, the rotational speed of the motor 27b in the electric valve timing device 27 in the advance direction is the deceleration ratio times the rotational speed detected by the crank angle sensor 6 (converted to the cam rotational speed). However, in the case where the rotational amount of the crankshaft 5 is within 6 deg. CA, there is also a case where the rotation cannot be detected by the crank angle sensor 6 and only the rotation of the motor 27b in the electric valve timing device 27 in the advance direction is detected. In the case where the phase shift amount is small and the crank angle sensor 6 cannot detect, the rotation of the intake camshaft supporting the intake cam 11 can be detected by the motor sensor. For example, the Hall IC sensor used in the present embodiment can detect a rotation of 0.42 degrees.

[0153] (Scene B)

[0154] This item is a case where, after the engine 50 is temporarily stopped, the engine start flag is not established, the rotation (pulse signal) is detected by the intake cam angle sensor 13, and the rotation (pulse signal) of the motor 27b in the advance direction is detected by the motor sensor in the electric valve timing device 27. At this time, the rotational speed of the motor 27b in the electric valve timing device 27 in the advance direction is the deceleration ratio times the rotational speed detected by the intake cam angle sensor 13. However, since the resolution of the intake cam angle sensor 13 is 180 deg. CA per interval, only the mode where the rotation of the motor 27b in the electric valve timing device 27 in the advance direction is detected. In this case, although the phenomenon is different, the detection content is the same as that shown in the latter half of the description of Scene A.

[0155] Step S9

[0156] The valve phase detection section 302 of the CPU 30 determines whether the phase of the intake valve 9 is the maximum lag based on the result of the calculation of step S8. That is, the valve phase detection section 302 determines whether an unexpected phase change (phase shift) of the valve timing has occurred. The valve phase detection section 302 receives a signal that detects Scenario A or Scenario B defined in step S8, and determines that the current phase of the intake valve 9 has not been the maximum lag but has undergone an unexpected phase change.

[0157] Basically, the valve phase detection section 302 determines that an unexpected change has occurred from the maximum lag and calculates that the current phase is not the maximum lag when the rotation of the motor 27b in the electric valve timing apparatus 27 is detected in a state where the engine start flag is not input after the engine is stopped. However, in the case where the rotation signals (pulse numbers) of the crank angle sensor 6 and the motor 27b are input at 2: 1, it is determined that both are following the relative phase, and thus it is not applicable. When the valve phase detection section 302 determines that the phase of the intake valve 9 is not the maximum lag (NO of S9), it proceeds to step S10, and when it determines that the phase of the intake valve 9 is the maximum lag (YES of S9), it proceeds to step S8.

[0158] Step S10

[0159] The valve phase detection section 302 of the CPU 30 calculates the phase shift amount of the intake valve 9 at the engine stop time from the maximum lag position as a relative value based on the signals of the crank angle sensor 6 or the intake cam angle sensor 13 and the rotation signal of the motor 27b in the electric valve timing apparatus 27 when the phase of the intake valve 9 is not the target phase (in this case, the maximum lag).

[0160] Step Sll

[0161] The phase change method selection section 303 of the CPU 30 grasps the relationship between the position of the cam lobe 11m and the operation of the electric valve timing apparatus 27 that changes the phase to the maximum lag side based on the relative phase of the intake valve 9 with respect to the crankshaft 5 calculated in step S10. At this time, as described with reference to FIG. 6, the phase change method selection section 303 determines the phase change method of the electric valve timing apparatus 27 based on the relative phase of the intake valve 9 with respect to the crankshaft 5. Figure 11 and Figure 12As explained, the relationship of the cam lobe 11m and the direction of the phase change of the intake cam 11 is obtained. The phase change method selection section 303 calculates which direction, the advance direction or the retard direction, the phase of the intake cam 11 is changed from the current relative phase of the intake cam 11 with respect to the final required phase (in this case, the maximum retard), at which the current value of the motor 27b becomes smaller, and thereby selects the phase change method. Actually, the phase change method selection section 303 selects the phase change method with reference to the map information 321 based on the current phase and the target phase of the intake cam 11. Here, in a case where the operation of the phase change control to the maximum retard side can be performed with a smaller motor current (YES in Sll), the process proceeds to step S12, and in a case where the operation of the phase change control to the maximum retard side cannot be performed with a smaller motor current (NO in Sll), the process proceeds to step S14.

[0162] <Step S12>

[0163] The phase change method selection section 303 of the CPU 30 selects the single operation (the first phase change method) in a case where the "YES" determination in the above step Sll is made. The flow in a case where the single operation is selected is shown in steps S12 and S13. The single operation, as explained in Figure 11

[0164] <Step S13>

[0165] The valve phase change section 304 of the CPU 30 outputs the instruction (PWM / Duty) of the rotational speed and the rotational direction corresponding to the rotation in the retard direction to the UVW control unit 27c in accordance with the single operation selected in step S12. Thereby, the drive signal for rotating in the retard direction is transmitted to the motor 27b in the electric valve timing apparatus 27 via the general-purpose IC 271 and the motor driver 272. The motor 27b rotates the drive rotor 28 to change the phase of the intake camshaft (the intake valve 9) to the maximum retard.

[0166] <Step S14>

[0167] The phase change method selection section 303 of the CPU 30 selects the double operation (the second phase change method) in a case where the "NO" determination in the above step Sll is made. The flow in a case where the double operation is selected is shown in steps S14 to S16. The double operation, as explained in Figure 12

[0168] <Step S15>​​

[0169] The valve phase changing unit 304 of CPU30, based on the dual action selected in step S14, as the first action, controls the phase of the intake valve 9 towards the opposite phase side (here, the advance side) of the target phase. For example... Figure 12 As shown, when the CPU30 envisions changing the phase of the intake cam 11 in a lag direction, with the apex of the cam lobe angle 11m abutting against the contact member 90—in other words, with the contact member 90 coming down from the cam lobe angle 11m after stepping onto it—the phase of the intake valve 9 is changed in an advanced direction (away from the target phase) that temporarily moves down from the cam lobe angle 11m. For example, the phase of the intake cam 11 can be advanced to the position where the contact member 90 is completely down from the cam lobe angle 11m, i.e., the contact point between the contact member 90 and the cam lobe angle 11m is at the same diameter as the minor diameter of the cam. When the contact point between the contact member 90 and the cam lobe angle 11m is at the same diameter as the minor diameter of the cam, since the intake cam 11 does not press against the contact member 90 and the valve spring, no load generated by the reaction force of the valve spring is applied to the intake cam 11.

[0170] Step S16

[0171] The valve phase change unit 304 of CPU 30, as the second action in a dual operation, controls the phase of the intake valve 9 to move closer to the target phase (here, the lag side). In step S15 above, the phase of the intake valve 9 is temporarily changed from the maximum lag required for the next engine start to the advanced direction on the opposite phase side. At this time, by advancing it to a position where it is completely down from the cam lobe angle 11m, and then changing the phase of the intake cam 11 closer to the target phase, the inrush current applied to the UVW control unit 27c can be suppressed. For example, CPU 30 provides an instruction from ECU 26 to UVW control unit 27c to change the phase of the intake valve 9 from the state where the intake camshaft is at the lowest point of the cam lobe angle 11m (the state where no load is applied to the intake cam 11) to the direction of maximum lag. Thus, CPU 30 performs control to change the phase of the intake valve 9 towards the maximum lag.

[0172] Step S17

[0173] The valve phase detection section 302 of the CPU 30 judges the current phase of the intake valve 9 after the phase change control to the maximum lag of the intake valve 9 in step S13 or step S16. Here, whether the intake valve 9 has changed to the maximum lag before the phase deviation occurs, i.e., the phase calculated in step S8, is taken as a judgment condition by the single action and the double action described above. At this time, the CPU 30 shifts to step S8 in the case where the intake valve 9 is judged to have changed to the maximum lag phase (YES in S17), and prepares for the occurrence of the phase deviation after the engine is stopped. On the other hand, the CPU 30 shifts to step Sll in the case where the phase of the intake valve 9 is judged not to be the maximum lag (NO in S17). Based on the judgment result of the current relative phase of the intake valve 9 in step Sll, the flow of the selective phase change action from step Sll to step S17 is performed again, and thus the phase change of the intake valve 9 to the maximum lag is performed.

[0174] Step S18

[0175] This step indicates the end condition of the change processing flow of the required phase change of the intake valve 9 at the next start after the engine is stopped from step S8 to step S17 described above. The end condition of this loop processing is the timing when the flag "ON" of the next engine start is input to the CPU 30. At this time, the phase of the intake valve 9 is calculated to be the maximum lag stop position 110 (the position where the end portion 28c of the drive rotating body 28 abuts against the convex portion 29a of the driven rotating body 29) by the series of processing steps up to this point.

[0176] As described above, the electric valve timing control device (ECU 26) of the first embodiment controls the electric valve timing device (VTC 27) which changes the valve timing by changing the relative rotation phase of the camshaft (e.g., the intake camshaft) with respect to the crankshaft of the internal combustion engine (engine 50) using the motor (motor 27b) linked to the camshaft. The electric valve timing control device has a control section (CPU 30: valve phase detection section 302, phase change method selection section 303) which changes the phase change method of changing the camshaft from the current phase to the target phase based on the relationship between the current phase and the target phase of the camshaft when the relative rotation phase of the camshaft is changed using the electric valve timing device after the stop processing of the internal combustion engine.

[0177] According to the first embodiment of the above-described structure, from before the internal combustion engine (engine 50) is about to stop to after the internal combustion engine is stopped, by grasping the relationship between the current phase of the camshaft (intake camshaft) (phase of the electric valve timing apparatus (VTC 27)) and the target phase (relative position of the intake camshaft and the cam lobe 11m), the phase change method (single action, double action) that changes the phase of the camshaft is switched. Thus, according to the relationship between the current phase of the camshaft and the target phase, the direction of rotation of the electric motor is instructed by the electric valve timing control apparatus (ECU 26). Therefore, overheat of the electric motor and the electric motor driver due to generation of excessive current is prevented, and the phase of the valve (intake valve 9) is controlled to an arbitrary phase from before the internal combustion engine is about to stop to after the internal combustion engine is stopped.

[0178] As described above, in the electric valve timing control apparatus (ECU 26) of the present embodiment, the control section (CPU 30: valve phase detection section 302, phase change method selection section 303) switches the first phase change method (single action) that rotates the camshaft in a first direction from the current phase toward the target phase to change the camshaft to the target phase and the second phase change method (double action) that rotates the camshaft in a second direction away from the target phase by a prescribed phase amount by a first action and then rotates the camshaft in the first direction by a second action to change the camshaft to the target phase, based on the relationship between the current phase of the camshaft and the target phase (e.g., maximum retard) when the relative rotational phase of the camshaft (intake camshaft) is changed by the electric valve timing apparatus (VTC 27) after the stop process of the internal combustion engine (engine 50).

[0179] According to such a structure, the electric valve timing control apparatus (ECU 26) selects either the first phase change method or the second phase change method according to the relationship between the current phase of the camshaft and the target phase, and the direction of rotation of the electric motor (electric motor 27b) is instructed from the electric valve timing control apparatus (ECU 26).

[0180] As described above, in the electric valve timing control apparatus (ECU 26) of the present embodiment, the control section (CPU 30: valve phase detection section 302, phase change method selection section 303) selects the first phase change method (single action) when the target phase of the camshaft (intake camshaft) is set in a region where the current flowing in the electric motor (electric motor 27b) is below the target current when the camshaft is rotated in a first direction from the current phase, and selects the second phase change method (double action) when the current flowing in the electric motor is above the target current.

[0181] According to such a structure, the electric valve timing control apparatus (ECU 26) selects either the first phase change method or the second phase change method in accordance with the relationship between the current phase of the camshaft and the target phase, and is able to prevent a current exceeding the target current from flowing in the motor (motor 27b).

[0182] As described above, in the electric valve timing control apparatus (ECU 26) of the present embodiment, the control section (CPU 30: valve phase detection section 302, phase change method selection section 303) selects the first phase change method (single action) in the case where the cam (for example, the intake cam 11) supported by the camshaft is rotated in the direction opposite to the direction in which the valve spring is pressed, and selects the second phase change method (double action) in the case where the intake cam or the exhaust cam is rotated in the direction in which the valve spring is pressed, when it is assumed that the camshaft (intake camshaft) is rotated in the first direction from the current phase.

[0183] According to such a structure, the electric valve timing control apparatus (ECU 26) selects the second phase change method (double action) in the case where the cam (intake cam 11) is rotated in the direction in which the valve spring is pressed when the camshaft (intake camshaft) is rotated. Thus, it is possible to suppress the maximum torque when the motor of the electric valve timing apparatus (VTC 27) is driven, and it is possible to reduce the current flowing in the motor.

[0184] As described above, in the electric valve timing control apparatus (ECU 26) of the present embodiment, the control section (CPU 30: valve phase detection section 302, phase change method selection section 303) selects the first phase change method (single action) in the case where the contact member (contact member 90) is rotated in the direction in which the contact member comes down from the cam lobe (cam lobe 11m) of the cam when it is assumed that the camshaft (intake camshaft) is rotated in the first direction from the current phase, and selects the second phase change method (double action) in the case where the contact member is rotated in the direction in which the contact member rides on the cam lobe, the contact member being provided between the cam supported by the camshaft and the valve spring.

[0185] According to such a structure, the electric valve timing control apparatus (ECU 26) selects the second phase change method (double action) in the case where the contact member (contact member 90) rides on the cam lobe (cam lobe 11m) when the camshaft (intake camshaft) is rotated. Thus, it is possible to suppress the maximum torque when the motor of the electric valve timing apparatus (VTC 27) is driven, and it is possible to reduce the current flowing in the motor.

[0186] As described above, in the electric valve timing control apparatus (ECU 26) of the present embodiment, the current phase of the camshaft (intake camshaft) is set on the first axis, the target phase of the camshaft is set on the second axis, and the mapping information (mapping information 321) defining the phase change method (single action, double action) at the intersection of the first axis and the second axis is defined, and the control section (CPU 30: valve phase detection section 302, phase change method selection section 303) switches the phase change method based on the current phase and the target phase of the camshaft, with reference to the mapping information.

[0187] According to such a configuration, the electric valve timing control apparatus (ECU 26) can easily select and switch the phase change method with reference to the mapping information, depending on the relationship between the current phase and the target phase of the camshaft.

[0188] As described above, in the electric valve timing control apparatus (ECU 26) of the present embodiment, the electric valve timing apparatus (VTC 27) includes a control unit (UVW control unit 27c) in which a motor sensor (Hall IC circuit) that outputs a signal corresponding to the rotation of the motor (motor 27b) is built in. The control section (CPU 30: valve phase detection section 302, phase change method selection section 303) receives the output signal of the motor sensor from the control unit of the electric valve timing apparatus as the motor speed and the motor rotation direction, to detect the phase change amount (speed) and the phase change direction (rotation direction) of the electric valve timing apparatus after the stop process of the internal combustion engine (engine 50).

[0189] According to such a configuration, the electric valve timing control apparatus (ECU 26) can obtain the motor speed and the motor rotation direction based on the output signal of the motor sensor even in the case where no signal is obtained from the crank angle sensor 6 and the intake cam angle sensor 13 after the stop process of the internal combustion engine (engine 50). Therefore, the phase of the valve (valves) can be controlled at an arbitrary phase with good accuracy from just before the internal combustion engine is stopped to after the internal combustion engine is stopped.

[0190] <Second Embodiment>

[0191] The basic structure of the engine and its surrounding equipment in the second embodiment is the same as that described in the first embodiment. Figure 1 The engine of the present embodiment is an engine of the type that adopts an early-closing Miller cycle. The early-closing Miller cycle refers to an engine cycle in which the intake valve 9 is closed before the piston 3 reaches the bottom dead center during the intake stroke of a four-stroke engine. The engine described in the present embodiment can establish an early-closing Miller cycle by causing the intake cam 11 to change phase to the advance side by the electric valve timing apparatus 27 mounted thereto.

[0192] Relationship between phase and lift amount of intake valve and exhaust valve in early-closing Miller cycle

[0193] In Figure 14 and Figure 15 , the profile curves of the intake valve 9 and the exhaust valve 10 in the early-closing Miller cycle are shown.

[0194] Figure 14 The profile curve 9f of the intake valve 9 in the case where the intake valve 9 is set at the maximum advance phase in the early-closing Miller cycle is shown.

[0195] Figure 15 The profile curve 9g of the intake valve 9 in the case where the intake valve 9 is set at the maximum retard phase in the early-closing Miller cycle is shown.

[0196] Figure 6 and Figure 7 , the horizontal axis shows the appearance of the engine stroke changing in the order of the expansion stroke, the exhaust stroke, the intake stroke, and the compression stroke, and the vertical axis shows the lift amount [mm] of the intake valve 9 and the exhaust valve 10. In the engine having the function of the early-closing Miller cycle, as the profile curve of the intake cam 11, there is a tendency that the cam width is narrow and the lift amount of the intake valve 9 is small, compared to the intake cam 11 of the engine having the function of the late-closing Miller cycle.

[0197] [Operation of electric valve timing control device]

[0198] In the early-closing Miller cycle, it is preferable to perform the engine restart in a state where the phase of the intake valve 9 is controlled at the maximum advance (profile curve 9f) at the time of the engine restart. In the engine having the early-closing Miller cycle, in contrast to the late-closing Miller cycle, it is possible to be the phase in which the intake valve 9 is opened at the middle of the exhaust stroke and the intake valve 9 is closed at the middle of the intake stroke in the stroke of the four-stroke engine. Therefore, by controlling the phase of the intake valve 9 at the maximum retard (profile curve 9g) at the time of the engine restart, it is possible to reduce the air flow amount in the engine cylinder at the time of the compression stroke. Therefore, at the time of the engine restart, it is possible to reduce the rotational speed variation at the time of the rotational rise of the crankshaft 5 and to suppress the vehicle body vibration (NVH: Noise, Vibration, Harshness) at the time of the engine restart. In the present embodiment, the phase change realized by the electric valve timing device 27 mounted on the intake camshaft makes this operation valid.

[0199] In the present embodiment, an idle stop command is input to the ECU 26, and the phase of the intake valve 9 is changed to the maximum advance after fuel injection is cut off, whereby, as described above, the phase of the intake valve 9 at the time of engine start can be started from the maximum advance. However, as in the first embodiment, after the engine is stopped, a phenomenon in which the phase of the electric valve timing device 27 controlled to the maximum advance is shifted to the retarding side with a certain probability occurs due to the reaction force of the cam lobe 11m, crank reversal immediately after the engine is stopped, and the like. Therefore, it is also required to control the phase of the intake valve 9 by the electric valve timing device 27 after the engine is stopped.

[0200] In the present embodiment, the phase change of the intake valve 9 occurring after the engine is stopped is calculated from the amount of shift from the phase of the intake valve 9 at the time of engine stop. As the direction of phase shift, since the intake valve 9 at the maximum advance phase at the time of engine stop is shifted to the retarding direction, it is required to change the phase of the intake valve 9 to the direction of the maximum advance after the phase shift is detected. Therefore, as the phase change control after the engine is stopped, it is required to rotate the intake camshaft to the advance side in the same direction as the engine rotation direction by the electric valve timing device 27.

[0201] However, as in the first embodiment, depending on the relative positional relationship between the phase of the intake cam 11 after the phase shift occurs and the maximum advance phase, the contact piece 90 passes over the cam lobe 11m due to the phase change. Thereby, in the phase change control, there is a possibility that an excessive current value is applied to the UVW control unit 27c. In the present embodiment, the purpose is to prevent the impact of the excessive current to the UVW control unit 27c.

[0202] [Electric Valve Timing Control Method]

[0203] Next, with respect to the electric valve timing control method in the first embodiment, the flowchart shown in FIG. 10 is described as an example of the sequence of the electric valve timing control method. Figure 16

[0204] Figure 16 is a flowchart showing an example of the sequence of the electric valve timing control method of the second embodiment. Here, as the requirement of the phase control at the time of next engine start, a series of actions from the phase change of the intake valve 9 to the maximum advance position from the time of engine stop to the restart is shown.

[0205] The details of each processing step of Figure 16 are substantially the same as the processing steps of Figure 13 in the first embodiment. The "retard" and "maximum retard" of steps S4, S5, S9, S11, S13, S16, and S17 of Figure 13 are shown in Figure 16 ​the steps S24, S25, S29, S31, S33, S36, S37 of the first embodiment are replaced with "advance" and "maximum advance". In contrast, the "advance" of the step S15 of the second embodiment is replaced with "retard". Figure 13 the step S35 of the second embodiment is replaced with "retard". Figure 16

[0206] [Effects of the Embodiment]

[0207] The second embodiment configured as described above not only can obtain the same effects as the first embodiment, but also can have the following effects. Assuming that the engine stop is encountered in a state where the phase of the intake valve 9 is controlled to the maximum advance at the time of engine stop, and the phase of the intake valve 9 is shifted after the engine stop, by adopting the structure of the embodiment, the relative phase shift amount from the maximum advance can be calculated. Further, based on the embodiment, the phase of the shifted intake valve 9 can be re-controlled to the maximum advance (profile curve 9f), and the engine can be started from the maximum advance even at the next engine restart.

[0208] [Modified Example]

[0209] In the first and second embodiments described above, an example in which the relative rotational phase of the intake camshaft with respect to the crankshaft 5 is changed by the electric valve timing apparatus 27 after the engine 50 is stopped is described, but the situation in which the present application can be applied is not limited to after the engine 50 is stopped. The present application is preferably used in a situation where, when it is assumed that the intake camshaft is rotated in a direction close to the target phase from the current phase, the target phase is set in a region where the current flowing in the motor 27b exceeds the target current. The lower the rotational speed of the engine 50, the more likely the motor current is to exceed the target current. Therefore, the present application can be applied before the engine 50 is about to stop and after the engine 50 is stopped in a state where the engine 50 is implemented after the stop process of the engine 50, i.e., in a state where the rotational speed of the engine 50 is below a predetermined value.

[0210] In the first and second embodiments described above, an example in which the ECU 26 controls the phase of the intake cam 11 (intake valve 9) with respect to the crankshaft 5 is described, but the present application can also be applied in a case where the ECU 26 controls the phase of the exhaust cam 12 (exhaust valve 10).

[0211] ​Further, the present application is not limited to the above-described embodiments, and various other applications and modifications can of course be made without departing from the spirit of the present application as recited in the claims. For example, the above-described embodiments are described in detail and specifically for the structure of the electric valve timing control apparatus in order to easily understand the present application, and are not limited to having all the described components. Also, a part of the structure of one embodiment can be replaced with a component of another embodiment. Also, a component of another embodiment can be added to the structure of one embodiment. Also, a part of the structure of each embodiment can be added, replaced, or deleted with another component.

[0212] Also, a part or all of each of the above-described structures, functions, processing sections, and the like can be realized by hardware using, for example, an integrated circuit or the like. As the hardware, a general-purpose processor device such as an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit) can be used.

[0213] Also, in the flowcharts shown in FIGS. 1 to 8, a plurality of processes can be implemented in parallel or the order of the processes can be changed within a range that does not affect the processing result. Figure 13 and Figure 16 In the flowcharts shown in FIGS. 1 to 8, a plurality of processes can be implemented in parallel or the order of the processes can be changed within a range that does not affect the processing result.

[0214] Explanation of Reference Numerals

[0215] 1…cylinder head, 2…cylinder block, 3…piston, 4…connecting rod, 5…crankshaft, 6…crank angle sensor, 7…intake pipe, 8…exhaust pipe, 9…intake valve, 9a…maximum advance intake valve profile curve (late-closing Miller cycle), 9b…maximum late intake valve profile curve (late-closing Miller cycle), 9c…single-action intake valve profile curve (late-closing Miller cycle), 9d…single-action intake valve profile curve (first action) (late-closing Miller cycle), 9e…single-action intake valve profile curve (second action) (late-closing Miller cycle), 9f…maximum advance intake valve profile curve (early-closing Miller cycle), 9g…maximum late intake valve profile curve (early-closing Miller cycle), 10…exhaust valve, 10a…exhaust valve profile curve (late-closing Miller cycle), 10b…exhaust valve profile curve (early-closing Miller cycle), 11…intake cam, 11m…cam lobe, 12…exhaust cam, 13…intake cam angle sensor, 14…injector, 15…spark plug, 16…ignition coil, 17…fuel tank, 18…intake pump, 19…high-pressure fuel pump, 20…common rail, 21…fuel pressure sensor, 22…three-way catalyst, 23…oxygen sensor, 24…temperature sensor, 25…water temperature sensor, 26…ECU (electronic valve timing control device), 27…electronic valve timing device, 27a…reducer, 27b…motor, 27c…UVW control unit, 27d…sprocket, 28…driving rotary body, 28a…recess, 28b…end portion (maximum advance stop), 28c…end portion (maximum late stop), 29…driven rotary body, 29a…projection, 90…contact piece, 271…general-purpose IC, 272…motor driver, 321…mapping information.

Claims

1. An electric valve timing control apparatus that controls an electric valve timing apparatus that changes valve timing by changing a relative rotation phase of a camshaft with respect to a crankshaft of an internal combustion engine using a motor coupled to the camshaft, characterized by comprising: a control portion that performs: a process of detecting a relationship between a current phase of the camshaft and a target phase after a stop process of the internal combustion engine; and a process of changing a plurality of phase changing methods of changing the camshaft from the current phase to the target phase based on the relationship between the current phase of the camshaft and the target phase when the relative rotation phase of the camshaft is changed using the electric valve timing apparatus, wherein the plurality of phase changing methods include a first phase changing method and a second phase changing method, wherein the first phase changing method, when the relative rotation phase of the camshaft is changed using the electric valve timing apparatus after the stop process of the internal combustion engine, changes the camshaft to the target phase by rotating the camshaft in a first direction that is closer to the target phase from the current phase based on the relationship between the current phase of the camshaft and the target phase, and wherein the second phase changing method changes the camshaft to the target phase by rotating the camshaft in a second direction that is farther from the target phase by a prescribed phase amount by a first action, and then rotating the camshaft in the first direction by a second action, and wherein the control portion selects the first phase changing method when the target phase of the camshaft from the current phase is set in a region in which a target current or less flows in the motor when the camshaft is rotated in the first direction from the current phase, and selects the second phase changing method when the target phase of the camshaft from the current phase is set in a region in which a current that exceeds the target current flows in the motor.

2. An electric valve timing control apparatus that controls an electric valve timing apparatus that changes valve timing by changing a relative rotation phase of a camshaft with respect to a crankshaft of an internal combustion engine using a motor coupled to the camshaft, characterized by comprising: a control portion that performs: a process of detecting a relationship between a current phase of the camshaft and a target phase after a stop process of the internal combustion engine; and a process of changing a plurality of phase changing methods of changing the camshaft from the current phase to the target phase based on the relationship between the current phase of the camshaft and the target phase when the relative rotation phase of the camshaft is changed using the electric valve timing apparatus, wherein the plurality of phase changing methods include a first phase changing method and a second phase changing method, wherein the first phase changing method, when the relative rotation phase of the camshaft is changed using the electric valve timing apparatus after the stop process of the internal combustion engine, changes the camshaft to the target phase by rotating the camshaft in a first direction that is closer to the target phase from the current phase based on the relationship between the current phase of the camshaft and the target phase, and wherein the second phase changing method changes the camshaft to the target phase by rotating the camshaft in a second direction that is farther from the target phase by a prescribed phase amount by a first action, and then rotating the camshaft in the first direction by a second action, and wherein the control portion selects the first phase changing method when the target phase of the camshaft from the current phase is set in a region in which a target current or less flows in the motor when the camshaft is rotated in the first direction from the current phase, and selects the second phase changing method when the target phase of the camshaft from the current phase is set in a region in which a current that exceeds the target current flows in the motor. ​ ​ ​ ​ ​ ​ ​ ​ ​ the first phase changing method, when the relative rotation phase of the camshaft is changed by the electric motor-driven valve timing apparatus after the stop process of the internal combustion engine, based on the relationship between the current phase of the camshaft and the target phase, rotating the camshaft in a first direction from the current phase toward the target phase to change the camshaft to the target phase, the second phase changing method, after rotating the camshaft in a second direction away from the target phase by a predetermined phase amount by a first action, rotating the camshaft in the first direction by a second action to change the camshaft to the target phase, the control section, when it is assumed that the camshaft is rotated in the first direction from the current phase, selecting the first phase changing method in a case where the contact member is rotated in a direction in which the contact member descends from a cam lobe of the cam supported by the camshaft, and selecting the second phase changing method in a case where the contact member is rotated in a direction in which the contact member ascends the cam lobe.

3. An electric motor-driven valve timing control device that controls an electric motor-driven valve timing apparatus that changes valve timing by changing a relative rotation phase of a camshaft with respect to a crankshaft of an internal combustion engine using a motor coupled to the camshaft, the electric motor-driven valve timing control device characterized by comprising: a control section that performs a process of detecting a relationship between a current phase of the camshaft and a target phase after a stop process of the internal combustion engine; and a plurality of phase changing methods for changing the camshaft from the current phase to the target phase based on the relationship between the current phase of the camshaft and the target phase when the relative rotation phase of the camshaft is changed by the electric motor-driven valve timing apparatus, the plurality of phase changing methods including a first phase changing method and a second phase changing method, wherein the first phase changing method, when the relative rotation phase of the camshaft is changed by the electric motor-driven valve timing apparatus after the stop process of the internal combustion engine, based on the relationship between the current phase of the camshaft and the target phase, rotating the camshaft in a first direction from the current phase toward the target phase to change the camshaft to the target phase, the second phase changing method, after rotating the camshaft in a second direction away from the target phase by a predetermined phase amount by a first action, rotating the camshaft in the first direction by a second action to change the camshaft to the target phase, the control section, when it is assumed that the camshaft is rotated in the first direction from the current phase, selecting the first phase changing method in a case where the contact member is rotated in a direction in which the contact member descends from a cam lobe of the cam supported by the camshaft, and selecting the second phase changing method in a case where the contact member is rotated in a direction in which the contact member ascends the cam lobe.

4. The electric motor-driven valve timing control device according to any one of claims 1 to 3, characterized by: The electric valve timing control device has map information that defines the phase change method at a first axis where the current phase of the camshaft is set and a second axis where the target phase of the camshaft is set, at an intersection of the first axis and the second axis, The control section switches the phase change method with reference to the map information based on the current phase and the target phase of the camshaft.

5. The electric valve timing control device according to any one of claims 1 to 3, characterized in that: The electric valve timing device has a control unit in which a motor sensor that outputs a signal corresponding to rotation of the motor is built in, The control section detects the phase change amount and the phase change direction of the electric valve timing device after the stop process of the internal combustion engine by receiving the output signal of the motor sensor from the control unit of the electric valve timing device as the motor rotation speed and the motor rotation direction.

6. An electric valve timing control method that is an electric valve timing control method using an electric valve timing control device that controls an electric valve timing device that changes valve timing by changing a relative rotation phase of a camshaft with respect to a crankshaft of an internal combustion engine using a motor that is linked to the camshaft, the electric valve timing control method being characterized by: A control section of the electric valve timing control device performs the following processes: a process of detecting a relationship between a current phase and a target phase of the camshaft after a stop process of the internal combustion engine; and a phase change process of changing the camshaft from the current phase to the target phase based on a result of the detection when the relative rotation phase of the camshaft is changed using the electric valve timing device, The phase change process includes a first phase change method and a second phase change method, wherein The first phase change method changes the camshaft to the target phase by rotating the camshaft in a first direction that is closer to the target phase from the current phase based on the relationship between the current phase and the target phase of the camshaft when the relative rotation phase of the camshaft is changed using the electric valve timing device after the stop process of the internal combustion engine, The second phase change method changes the camshaft to the target phase by rotating the camshaft in the first direction after rotating the camshaft in a second direction that is farther from the target phase by a predetermined phase amount by a first action and then rotating the camshaft in the first direction by a second action, The first phase change method is executed when the target phase of the camshaft is set in a region where a current that is below a target current flows in the motor when the camshaft is rotated in the first direction from the current phase, and the second phase change method is executed when the target phase of the camshaft is set in a region where a current that exceeds the target current flows in the motor.

7. An electric valve timing control method that is an electric valve timing control method performed by an electric valve timing control device that controls an electric valve timing device that changes valve timing by changing a relative rotation phase of a camshaft with respect to a crankshaft of an internal combustion engine using a motor linked to the camshaft, characterized by: a control section of the electric valve timing control device performing the following processes: a process of detecting a relationship of a current phase of the camshaft with respect to a target phase after a stop process of the internal combustion engine; and a phase changing process of changing the camshaft from the current phase to the target phase based on a result of the detection when the relative rotation phase of the camshaft is changed using the electric valve timing device, the phase changing process including a first phase changing method and a second phase changing method, wherein the first phase changing method, when the relative rotation phase of the camshaft is changed using the electric valve timing device after the stop process of the internal combustion engine, changes the camshaft to the target phase by rotating the camshaft in a first direction that is closer to the target phase from the current phase based on the relationship of the current phase of the camshaft with respect to the target phase, the second phase changing method changes the camshaft to the target phase by rotating the camshaft in the first direction by a second action after rotating the camshaft in a second direction that is farther from the target phase by a first action by a predetermined phase amount, in a case where it is assumed that the camshaft is rotated in the first direction from the current phase, the first phase changing method is performed in a case where the camshaft is rotated in a direction opposite to a direction in which a cam supported by the camshaft presses a valve spring, and the second phase changing method is performed in a case where the cam is rotated in the direction in which the cam presses the valve spring.

8. An electric valve timing control method that is an electric valve timing control method performed by an electric valve timing control device that controls an electric valve timing device that changes valve timing by changing a relative rotation phase of a camshaft with respect to a crankshaft of an internal combustion engine using a motor linked to the camshaft, characterized by: a control section of the electric valve timing control device performing the following processes: a process of detecting a relationship of a current phase of the camshaft with respect to a target phase after a stop process of the internal combustion engine; and a phase changing process of changing the camshaft from the current phase to the target phase based on a result of the detection when the relative rotation phase of the camshaft is changed using the electric valve timing device, the phase changing process including a first phase changing method and a second phase changing method, wherein the first phase changing method, when the relative rotation phase of the camshaft is changed using the electric valve timing device after the stop process of the internal combustion engine, changes the camshaft to the target phase by rotating the camshaft in a first direction that is closer to the target phase from the current phase based on the relationship of the current phase of the camshaft with respect to the target phase, the second phase changing method changes the camshaft to the target phase by rotating the camshaft in the first direction by a second action after rotating the camshaft in a second direction that is farther from the target phase by a first action by a predetermined phase amount, in a case where it is assumed that the camshaft is rotated in the first direction from the current phase, the first phase changing method is performed in a case where the camshaft is rotated in a direction opposite to a direction in which a cam supported by the camshaft presses a valve spring, and the second phase changing method is performed in a case where the cam is rotated in the direction in which the cam presses the valve spring. The first phase changing method, when changing the relative rotation phase of the camshaft using the electric cam timing device after the stop process of the internal combustion engine, changes the camshaft to the target phase by rotating the camshaft in a first direction from the current phase toward the target phase based on the relationship between the current phase and the target phase of the camshaft, The second phase changing method, by changing the camshaft to the target phase by rotating the camshaft in a second direction away from the target phase by a prescribed phase amount by a first action, and then rotating the camshaft in the first direction by a second action, In the case where the contact member is rotated in a direction in which it comes off the cam lobe of the cam, the first phase changing method is executed when it is assumed that the camshaft is rotated in the first direction from the current phase, wherein the contact member is provided between the cam supported by the camshaft and a valve spring, and in the case where the contact member is rotated in a direction in which it rides up the cam lobe, the second phase changing method is executed.

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