WO2021002252A1 - Control device for variable valve timing mechanism and control method of same - Google Patents

Abstract

A control device for a variable valve timing mechanism comprises a controller that detects a phase angle of a cam on the basis of a cam angle signal, and controls the phase angle of the cam by using an electric motor. When the cam angle signal is detected, the controller updates the phase angle of the cam from when the cam angle signal was detected the previous time. While the phase angle of the cam is detected, motor rotation velocity is computed on the basis of motor drive current and an engine operation state, and a motor rotation angle is computed on the basis of the motor rotation velocity and the phase angle of the cam is estimated. Also, the controller interpolates the phase angle of the cam from the motor rotation angle, and changes an estimated value of the motor rotation velocity, the value having been calculated on the basis of the motor drive current and the engine operation state, to a computation value based on the cam angle signal and the number of engine revolutions.

Description

Variable valve timing mechanism control device and its control method

The present invention relates to a control device for a variable valve timing mechanism that estimates a VTC (Variable valve Timing Control) angle from a motor drive current, and a control method thereof.

Patent Document 1 describes an electric valve timing adjusting device that adjusts the valve timing of an engine by using the rotational torque of a motor. In Patent Document 1, the phase of the camshaft with respect to the actual crankshaft (camshaft phase) is calculated based on the camshaft angle, crankshaft angle, lubricating oil temperature, cooling water temperature, and motor shaft rotation angle. At the same time, the target camshaft phase is calculated according to the engine operating conditions. At this time, since the camshaft phase is calculated in synchronization with the engine rotation angle, the update is delayed at low rotation speeds. Therefore, the rotation angle of the motor shaft is detected by using the motor rotation angle sensor, and the phase angle of the variable valve timing (VTC) mechanism is interpolated by the measured value.

Japanese Unexamined Patent Publication No. 2013-83187

By the way, for the purpose of reducing the cost of the VTC system, the non-installation of the motor rotation angle sensor is being considered. In order to ensure the controllability of the phase angle of the cam without using a sensor, it is conceivable to interpolate the phase angle with an estimated value. However, if the estimated value deviates from the actual phase angle, the controllability deteriorates according to the degree of dissociation.

The present invention has been made in view of the above circumstances, and an object of the present invention is a control device for a variable valve timing mechanism capable of suppressing a deviation between an actual angle and an estimated angle without using a motor rotation angle sensor. And its control method.

The control device for the variable valve timing mechanism and the control method thereof according to one aspect of the present invention is a variable valve timing mechanism that detects the phase angle of the cam based on the cam angle signal and controls the phase angle of the cam using an electric motor. When the cam angle signal is detected, the phase angle of the cam when the previous cam angle signal is detected is updated, and the motor is driven during the detection of the phase angle of the cam. The motor rotation speed (rotation speed of the electric motor) is calculated based on the current (driving current of the electric motor) and the engine operating state, and the motor rotation angle (rotation angle of the electric motor) is calculated based on the motor rotation speed. The phase angle of the cam is estimated, the phase angle of the cam is interpolated from the motor rotation angle, and the estimated value of the motor rotation speed calculated based on the motor drive current and the engine operating state is used as the cam angle. It is characterized by changing to a calculated value based on a signal and an engine speed.

According to the present invention, the motor rotation angle sensor can be obtained by changing the estimated value of the motor rotation speed calculated based on the motor drive current and the engine operating state to a calculated value based on the cam angle signal and the engine rotation speed. It is possible to suppress the deviation between the actual angle and the estimated angle without using it. As a result, it is possible to reduce the application of an inaccurate operating voltage to the VTC mechanism. As a result, the convergence of the VTC mechanism with respect to the target angle can be improved, and deterioration of vehicle performance can be suppressed.

It is a system block diagram of the internal combustion engine to which the control device of the variable valve timing mechanism which concerns on embodiment of this invention is applied. It is a waveform diagram of the crank angle signal and the cam angle signal in FIG. It is sectional drawing which shows the variable valve timing mechanism in FIG. FIG. 3 is a cross-sectional view taken along the line AA of FIG. FIG. 3 is a cross-sectional view taken along the line BB of FIG. It is a block diagram which extracts and shows the main part related to the control of the variable valve timing mechanism in the control device shown in FIG. It is a schematic diagram for demonstrating the calculation of the motor rotation speed using a crank angle signal and a cam angle signal. It is a waveform diagram for demonstrating the calculation of the cam rotation speed using a crank angle signal and a cam angle signal. It is a functional block diagram of the electric VTC controller shown in FIG. It is a waveform figure for demonstrating the calculation for calculating a motor rotation speed. It is a waveform diagram for demonstrating the example of a cam angle signal and the calculation of a cam rotation speed. It is for demonstrating the calculation method of the engine speed, and is the waveform diagram other than the missing part of the crank angle signal. This is a waveform diagram for explaining a method of calculating the engine speed, and is a waveform diagram when the rising edge of the cam angle signal overlaps with the missing tooth portion of the crank angle signal. This is a waveform diagram for explaining the timing of calculating and calibrating the motor rotation speed, and is a waveform diagram when the period from the previous fall of the crank angle signal to the rise of the cam angle signal is short. It is for explaining the execution timing of calculation and calibration of the motor rotation speed, and is a waveform diagram when the period from the fall of the previous crank angle signal to the rise of the cam angle signal is long and the next update is closer. is there. It is a waveform figure for demonstrating the correction of the estimated value of a motor rotation speed. It is a waveform diagram for demonstrating learning of the period from the fall to the rise of a cam angle signal. It is a waveform diagram for demonstrating the calculation and correction of a motor rotation speed according to an engine rotation speed. It is a waveform diagram which shows the simulation result which compared the difference between the real angle and the estimated angle of the VTC mechanism in the prior art and the present invention. It is an enlarged view of the area surrounded by the broken line in FIG. It is a waveform diagram which shows the simulation result which compared the VTC angle in the prior art and this invention. It is a waveform figure which shows the simulation result which compared the operation voltage in the prior art and this invention. It is an enlarged view of the area surrounded by the broken line in FIG. 19A. It is an enlarged view of the area surrounded by the broken line in FIG. 19B.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system configuration diagram of an internal combustion engine to which the control device of the variable valve timing mechanism according to the embodiment of the present invention is applied.
The internal combustion engine (engine) 100 is mounted on a vehicle and used as a power source. The internal combustion engine 100 may be of various types such as a V type or a horizontally opposed type in addition to the series type shown in the figure.

The intake duct 102 of the internal combustion engine 100 is provided with an intake air amount sensor 103 that detects the intake air flow rate QA of the internal combustion engine 100.
The intake valve 105 opens and closes the intake port of the combustion chamber 104 of each cylinder. A fuel injection valve 106 is arranged for each cylinder at the intake port 102a on the upstream side of the intake valve 105. Here, an example is taken in which the fuel injection valve 106 injects fuel into the intake duct 102, but an in-cylinder direct injection type internal combustion engine that injects fuel directly into the combustion chamber 104 may be used.

The fuel injected from the fuel injection valve 106 is sucked together with air into the combustion chamber 104 through the intake valve 105, ignited and burned by spark ignition by the spark plug 107, and the pressure generated by the combustion causes the piston 108 to the crankshaft 109. The crankshaft 109 is rotationally driven by pushing it down toward it.
Further, the exhaust valve 110 opens and closes the exhaust port of the combustion chamber 104, and when the exhaust valve 110 opens, the exhaust gas in the combustion chamber 104 is discharged to the exhaust pipe 111.

A catalyst converter 112 provided with a three-way catalyst or the like is installed in the exhaust pipe 111, and the exhaust gas is purified by the catalyst converter 112.
The intake valve 105 opens as the intake camshaft 115a, which is rotationally driven by the crankshaft 109, rotates. Further, the exhaust valve 110 opens as the exhaust camshaft 115b, which is rotationally driven by the crankshaft 109, rotates.

The VTC mechanism 114 uses an electric motor (brushed DC motor) as an actuator to change the relative rotation phase angle of the intake camshaft 115a with respect to the crankshaft 109, thereby changing the phase of the valve operating angle of the intake valve 105, that is, intake air. It is an electric VTC mechanism that continuously changes the valve timing of the valve 105 in the advance direction and the retard direction.
Further, an ignition module 116 for supplying ignition energy to the spark plug 107 is directly attached to the spark plug 107 provided for each cylinder. The ignition module 116 includes an ignition coil and a power transistor that controls energization of the ignition coil.

The control device (electronic control unit) 201 includes an electric VTC controller 201a that drives and controls the VTC mechanism 114, and an engine control module (hereinafter referred to as ECM) 201b that controls a fuel injection valve 106, an ignition module 116, and the like. There is. Each of the electric VTC controllers 201a and ECM201b is equipped with a microcomputer including a CPU, RAM, ROM, etc., and performs arithmetic processing according to a program stored in advance in a memory such as ROM to calculate and output the operation amount of various devices. To do. Further, the electric VTC controller 201a includes a drive circuit such as an inverter that drives the electric motor of the VTC mechanism 114.

These electric VTC controllers 201a and ECM201b are configured to be able to transfer data to each other via CAN (Controller Area Network) 201c.
In addition to the electric VTC controllers 201a and ECM201b, an AT controller that controls an automatic transmission combined with an internal combustion engine is connected to the CAN201c as a communication network.

In addition to inputting the intake air flow rate QA output from the intake air amount sensor 103 to the control device 201, the crank angle sensor 203 and the accelerator pedal 207 output the rotation angle signal (referred to as the crank angle signal) POS of the crankshaft 109. The amount of depression, in other words, the accelerator opening sensor 206 that detects the accelerator opening ACC, the cam angle sensor 204 that outputs the rotation angle signal (called the cam angle signal) CAM of the intake camshaft 115a, and the cooling water of the internal combustion engine 100. Water temperature sensor 208 that detects the temperature TW, air-fuel ratio sensor 209 that is installed in the exhaust pipe 111 on the upstream side of the catalytic converter 112 and detects the air-fuel ratio AF based on the oxygen concentration in the exhaust, in the oil pan (or engine oil) The output signal from the oil temperature sensor 210 or the like that detects the oil temperature TO of the engine oil in the circulation path) is input, and further, from the ignition switch (engine switch) 205 that is the main switch for starting and stopping the internal combustion engine 100. The signal IGNSW is input.

FIG. 2 shows an example of the signal patterns of the crank angle signal POS and the cam angle signal CAM. The crank angle signal POS output by the crank angle sensor 203 is a pulse signal for each unit crank angle (for example, 10 deg.CA), and is a crank angle (4-cylinder engine) corresponding to a stroke phase difference (ignition interval) between cylinders. The signal pattern is configured so that one or more pulses are missing for each crank angle (180 deg).
Further, the crank angle sensor 203 outputs a rotation angle signal POS (unit crank angle signal) for each unit crank angle and a reference crank angle signal for each crank angle corresponding to the stroke phase difference (ignition interval) between cylinders. Can be configured as Here, the missing portion of the unit crank angle signal POS or the output position of the reference crank angle signal represents the reference piston position of each cylinder.

The cam angle sensor 204 outputs a cam angle signal CAM for each crank angle corresponding to the stroke phase difference (ignition interval) between cylinders.
Here, since the intake camshaft 115a rotates at half the rotation speed of the crankshaft 109, the internal combustion engine 100 is a 4-cylinder engine, and the crank angle corresponding to the stroke phase difference (ignition interval) between the cylinders is 180 deg. .. In the case of CA, the crank angle is 180 deg. CA corresponds to a rotation angle of 90 deg of the intake camshaft 115a. That is, the cam angle sensor 204 outputs a cam angle signal CAM every time the intake camshaft 115a rotates 90 deg.

The cam angle signal CAM is a signal (cylinder discrimination signal) for discriminating the cylinder located at the reference piston position, and represents the cylinder number for each crank angle corresponding to the stroke phase difference (ignition interval) between the cylinders. It is output as a characteristic pulse.
For example, in the case of a 4-cylinder engine in which the ignition order is the first cylinder, the third cylinder, the fourth cylinder, and the second cylinder, the cam angle sensor 204 has two consecutive pulse signals for every 180 deg crank angle. By outputting one pulse signal, one pulse signal, and two consecutive pulse signals in this order, the cylinder located at the reference piston position can be specified based on the number of pulses. Further, the cam angle signal CAM can represent the cylinder number based on the number of pulses, or can represent the cylinder number based on the pulse width and amplitude.

3 to 5 show an example of the structure of the VTC mechanism 114 in FIG. 1, respectively.
The structure of the VTC mechanism 114 is not limited to that illustrated in FIGS. 3 to 5, and a voltage is applied to the brushed DC motor only during phase conversion to make the motor shaft portion relative to the sprocket portion. Other configurations can be adopted as long as they are rotated to change the phase of the camshaft.

As shown in FIG. 3, the VTC mechanism 114 is rotatably mounted on a cylinder head via a bearing 44 and a timing sprocket (cam sprocket) 1 which is a drive rotating body rotationally driven by a crankshaft 109 of the internal combustion engine 100. An intake camshaft 115a that is supported and rotates by a rotational force transmitted from the timing sprocket 1, a cover member 3 that is arranged in front of the timing sprocket 1 and fixed to the chain cover 40 by bolts, and a timing sprocket 1. A phase changing mechanism 4 which is arranged between the intake camshafts 115a and changes the relative rotation phase angle of the intake camshaft 115a with respect to the timing sprocket 1 is provided.

The timing sprocket 1 is composed of a sprocket body 1a and a gear portion 1b that is integrally provided on the outer periphery of the sprocket body 1a and receives a rotational force from a crankshaft 109 via a wound timing chain 42. ..
Further, the timing sprocket 1 is interposed between the circular groove 1c formed on the inner peripheral side of the sprocket body 1a and the outer periphery of the flange portion 2a integrally provided at the front end portion of the intake camshaft 115a. It is rotatably supported by the intake camshaft 115a by the ball bearing 43.

An annular protrusion 1e is integrally formed on the outer peripheral edge of the front end portion of the sprocket body 1a.
At the front end of the sprocket body 1a, an annular member 19 which is coaxially positioned on the inner peripheral side of the annular protrusion 1e and has internal teeth 19a which are corrugated meshing portions on the inner circumference, and an annular plate 6 Is fastened and fixed together with the bolt 7 from the axial direction.

Further, as shown in FIG. 5, a stopper convex portion 1d, which is an arc-shaped engaging portion, is formed on a part of the inner peripheral surface of the sprocket body 1a up to a predetermined length range along the circumferential direction.
A cylindrical housing 5 projecting forward while covering each component of the speed reducer 8 and the electric motor 12, which will be described later of the phase changing mechanism 4, is fixed to the outer periphery of the plate 6 on the front end side by bolts 11.

The housing 5 is formed of an iron-based metal and functions as a yoke, and has an annular plate-shaped holding portion 5a integrally on the front end side, and the entire outer peripheral side including the holding portion 5a is covered by the cover member 3. It is arranged so as to be covered with a predetermined gap.
The intake camshaft 115a has a drive cam (not shown) that opens and operates the intake valve 105 on the outer periphery thereof, and a driven member 9 that is a driven rotating body at the front end is axially coupled by a cam bolt 10.

Further, as shown in FIG. 5, a stopper concave groove 2b, which is a locking portion in which the stopper convex portion 1d of the sprocket body 1a engages, is formed in the flange portion 2a of the intake camshaft 115a along the circumferential direction. ing.
The stopper concave groove 2b is formed in an arc shape having a predetermined length in the circumferential direction, and both end edges of the stopper convex portion 1d rotated in this length range abut on the opposing edges 2c and 2d in the circumferential direction, respectively. Therefore, the relative rotation positions of the intake camshaft 115a with respect to the timing sprocket 1 on the maximum advance side and the maximum retard side are regulated.

That is, the angle range in which the stopper convex portion 1d can move in the stopper concave groove 2b is the variable range of the relative rotation phase angle of the intake camshaft 115a with respect to the crankshaft 109, in other words, the variable range of the valve timing.
A flange-shaped seating surface portion 10c is integrally formed on the end edge of the head portion 10a of the cambolt 10 on the shaft portion 10b side, and is formed on the outer periphery of the shaft portion 10b in the internal axial direction from the end portion of the intake camshaft 115a. A male screw portion to be screwed to the female screw portion is formed.

The driven member 9 is formed of an iron-based metal material, and as shown in FIG. 4, is composed of a disk portion 9a formed on the front end side and a cylindrical cylindrical portion 9b integrally formed on the rear end side. Has been done.
The disk portion 9a is integrally provided with an annular step protrusion 9c having substantially the same outer diameter as the flange portion 2a of the intake camshaft 115a at a substantially central position in the radial direction of the rear end surface.

The outer peripheral surface of the annular step protrusion 9c and the outer peripheral surface of the flange portion 2a are inserted and arranged on the inner circumference of the inner ring 43a of the third ball bearing 43. The outer ring 43b of the third ball bearing 43 is press-fitted and fixed to the inner peripheral surface of the circular groove 1c of the sprocket body 1a.
Further, a cage 41 for holding a plurality of rollers 34 is integrally provided on the outer peripheral portion of the disk portion 9a.

The cage 41 is formed so as to project from the outer peripheral portion of the disk portion 9a in the same direction as the cylindrical portion 9b, and is formed by a plurality of elongated protrusions 41a having predetermined gaps at positions substantially equally spaced in the circumferential direction. ing.
The cylindrical portion 9b is formed with an insertion hole 9d through which the shaft portion 10b of the cam bolt 10 is inserted in the center, and a first needle bearing 28 is provided on the outer peripheral side of the cylindrical portion 9b.

The cover member 3 is formed of a synthetic resin material and is composed of a cover body 3a that bulges like a cup and a bracket 3b that is integrally provided on the outer periphery of the rear end portion of the cover body 3a.
The cover main body 3a is arranged so as to cover substantially the entire front end side of the phase changing mechanism 4, that is, the housing 5 from the axial holding portion 5b to the rear end portion side with a predetermined gap. On the other hand, the bracket 3b is formed in a substantially annular shape, and bolt insertion holes 3f are formed through the six boss portions, respectively.

Further, a bracket 3b is fixed to the cover member 3 via a plurality of bolts 47 to the chain cover 40, and double inner and outer slip rings 48a and 48b are provided on the inner peripheral surface of the front end portion 3c of the cover body 3a. It is buried and fixed with the end face exposed.
Further, the upper end portion of the cover member 3 is provided with a connector portion 49 in which slip rings 48a and 48b and a connector terminal 49a connected via a conductive member are fixed.

The connector terminal 49a is supplied with power from a battery power source (not shown) via the control device 201.
A large-diameter first oil seal 50, which is a sealing member, is interposed between the inner peripheral surface on the rear end side of the cover body 3a and the outer peripheral surface of the housing 5.

The first oil seal 50 is formed to have a substantially U-shaped cross section, a core metal is embedded inside a synthetic rubber base material, and an annular base portion 50a on the outer peripheral side is inside the rear end portion of the cover body 3a. It is fitted and fixed in the circular groove 3d formed on the peripheral surface.
Further, a seal surface 50b that abuts on the outer peripheral surface of the housing 5 is integrally formed on the inner peripheral side of the annular base portion 50a of the first oil seal 50.

The phase changing mechanism 4 includes an electric motor 12 arranged substantially coaxially on the front end side of the intake camshaft 115a, and a speed reducer 8 that reduces the rotational speed of the electric motor 12 and transmits it to the intake camshaft 115a. ing.
The electric motor 12 is a DC motor with a brush, and has a housing 5 which is a yoke that rotates integrally with the timing sprocket 1, a motor shaft 13 which is an output shaft rotatably provided inside the housing 5, and a housing. A pair of semi-arc-shaped permanent magnets 14 and 15 fixed to the inner peripheral surface of No. 5 and a stator 16 fixed to the inner bottom surface side of the holding portion 5a are provided.

The motor shaft 13 is formed in a tubular shape and functions as an armature. An iron core rotor 17 having a plurality of poles is fixed to the outer periphery at a substantially central position in the axial direction, and an electromagnetic coil 18 is provided on the outer periphery of the iron core rotor 17. It is being wound.
A commutator 20 is press-fitted and fixed to the outer periphery of the front end portion of the motor shaft 13, and an electromagnetic coil 18 is connected to the commutator 20 in each segment divided into the same number as the number of poles of the iron core rotor 17.

The motor shaft 13 is a needle bearing 28, which is the first bearing, and a fourth ball, which is a bearing arranged on the axial side of the needle bearing 28, on the outer peripheral surface of the shaft portion 10b on the head portion 10a side of the cam bolt 10. It is rotatably supported via a bearing 35.
Further, a cylindrical eccentric shaft portion 30 forming a part of the speed reducer 8 is integrally provided at the rear end portion of the motor shaft 13 on the intake camshaft 115a side.

A second oil seal 32, which is a friction member that prevents the lubricating oil from leaking from the inside of the speed reducer 8 into the electric motor 12, is provided between the outer peripheral surface of the motor shaft 13 and the inner peripheral surface of the plate 6. Has been done.
The inner peripheral portion of the second oil seal 32 comes into contact with the outer peripheral surface of the motor shaft 13 to impart frictional resistance to the rotation of the motor shaft 13.

The speed reducer 8 includes an eccentric shaft portion 30 that performs eccentric rotational movement, a second ball bearing 33 that is a second bearing provided on the outer periphery of the eccentric shaft portion 30, and a roller provided on the outer periphery of the second ball bearing 33. It is mainly composed of 34, a cage 41 that allows the roller 34 to move in the radial direction while holding the roller 34 in the rolling direction, and a driven member 9 that is integrated with the cage 41.
The axis of the cam surface formed on the outer peripheral surface of the eccentric shaft portion 30 is slightly eccentric in the radial direction from the axis X of the motor shaft 13. The second ball bearing 33, the roller 34, and the like are configured as planetary meshing portions.

The second ball bearing 33 is formed in a large diameter shape and is arranged so as to substantially overlap at the radial position of the first needle bearing 28, and the inner ring 33a of the second ball bearing 33 is an eccentric shaft portion 30. The roller 34 is always in contact with the outer peripheral surface of the outer ring 33b of the second ball bearing 33 while being press-fitted and fixed to the outer peripheral surface.
Further, an annular gap C is formed on the outer peripheral side of the outer ring 33b, and the entire second ball bearing 33 can move in the radial direction along with the eccentric rotation of the eccentric shaft portion 30, that is, the eccentric movement becomes possible. It has become.

Each roller 34 fits into the internal teeth 19a of the annular member 19 while moving in the radial direction with the eccentric movement of the second ball bearing 33, and is guided in the radial direction by the protrusion 41a of the cage 41 in the radial direction. It is designed to swing.
Lubricating oil is supplied to the inside of the speed reducer 8 from the lubricating oil supply mechanism.

The lubricating oil supply mechanism is formed in the oil supply passage 44a formed inside the bearing 44 of the cylinder head and supplied with lubricating oil from the main oil gallery (not shown), and is formed in the internal axial direction of the intake cam shaft 115a to supply oil. An oil supply hole 48 that communicates with the passage 44a via a groove groove, and one end of the driven member 9 that is formed through the oil supply hole 48 in the internal axial direction and the other end of which is the first needle bearing 28 and the second ball bearing. It is composed of a small-diameter oil supply hole 45 opened in the vicinity of 33, and three large-diameter oil discharge holes (not shown) that are also formed through the driven member 9.

Next, the operation of the VTC mechanism 114 described above will be described.
First, when the crankshaft 109 of the internal combustion engine 100 is rotationally driven, the timing sprocket 1 rotates via the timing chain 42, and the rotational force causes the electric motor 12 to rotate synchronously via the housing 5, the annular member 19, and the plate 6. ..

On the other hand, the rotational force of the annular member 19 is transmitted from the roller 34 to the intake camshaft 115a via the cage 41 and the driven member 9. As a result, the cam of the intake camshaft 115a opens and closes the intake valve 105.
Then, when the VTC mechanism 114 changes the relative rotation phase angle of the intake camshaft 115a with respect to the crankshaft 109, that is, the valve timing of the intake valve 105, the control device 201 energizes the electromagnetic coil 18 of the electric motor 12. The electric motor 12 is driven. When the electric motor 12 is rotationally driven, this motor rotational force is transmitted to the intake camshaft 115a via the speed reducer 8.

That is, when the eccentric shaft portion 30 rotates eccentrically with the rotation of the motor shaft 13, each roller 34 is guided in the radial direction by the protrusion 41a of the cage 41 for each rotation of the motor shaft 13, and is one of the annular members 19. It overcomes the internal teeth 19a and moves while rolling to other adjacent internal teeth 19a, and this is sequentially repeated to transfer in the circumferential direction.
Rotational force is transmitted to the driven member 9 while the rotation of the motor shaft 13 is decelerated by the rolling and contacting of each roller 34. The reduction ratio when the rotation of the motor shaft 13 is transmitted to the driven member 9 can be arbitrarily set depending on the number of rollers 34 and the like.

As a result, the intake camshaft 115a rotates forward and reverse relative to the timing sprocket 1 to convert the relative rotation phase angle, and the opening / closing timing of the intake valve 105 is changed to the advance angle side or the retard angle side.
Here, the forward / reverse relative rotation of the intake camshaft 115a with respect to the timing sprocket 1 is regulated by each side surface of the stopper convex portion 1d coming into contact with either one of the opposite edges 2c or 2d of the stopper concave groove 2b.

That is, the driven member 9 rotates in the same direction as the rotation direction of the timing sprocket 1 with the eccentric rotation of the eccentric shaft portion 30, so that one side surface of the stopper convex portion 1d faces the stopper concave groove 2b on one side. It abuts on the edge 2c and further rotation in the same direction is restricted. As a result, the rotation phase angle of the intake camshaft 115a with respect to the timing sprocket 1 is changed to the maximum on the advance side.

On the other hand, when the driven member 9 rotates in the direction opposite to the rotation direction of the timing sprocket 1, the other side surface of the stopper convex portion 1d comes into contact with the opposite edge 2d on the other side of the stopper concave groove 2b and further in the same direction. Rotation is regulated. As a result, the rotation phase of the intake camshaft 115a with respect to the timing sprocket 1 is changed to the maximum on the retard side.
In this way, the control device 201 variably controls the relative rotation phase angle of the intake camshaft 115a with respect to the crankshaft 109, that is, the valve timing of the intake valve 105 by controlling the energization of the electric motor 12 of the VTC mechanism 114. ..

The control device 201 has a target phase angle (in other words, a target advance amount, a target valve timing, a target conversion angle) based on an operating state of the internal combustion engine 100, for example, an engine load, an engine rotation speed, an engine temperature, a starting state, and the like. ) Is calculated, while the actual relative rotation phase angle of the intake camshaft 115a with respect to the crankshaft 109 is detected.
Then, the control device 201 performs feedback control of the rotation phase by calculating and outputting the operation amount of the electric motor 12 so that the actual relative rotation phase angle approaches the target phase angle. In the feedback control, the control device 201 calculates the operation amount of the electric motor 12 by, for example, proportional integration control based on the deviation between the target phase angle and the actual relative rotation phase angle.

FIG. 6 extracts and shows the main parts related to the control of the VTC mechanism 114 in the control device 201 shown in FIG. The signal IGNSW from the ignition switch 205 connected to the battery VBAT is input to the ECM201b and the electric VTC controller 201a, respectively, and is activated by the ignition on. The ECM201b includes an input circuit 211 and a CPU 212. The cam angle signal CAM from the cam angle sensor 204 and the crank angle signal POS from the crank angle sensor 203 are input to the input circuits 211 and the CPU 212, respectively. The ECM201b controls the fuel injection valve 106, the ignition module 116, and the like based on these signals.

The CPU 212 calculates, for example, the target value (target phase angle) TGVTC (deg.CA) of the rotation phase adjusted by the VTC mechanism 114 based on the engine operating state, and the crank angle signal POS from the crank angle sensor 203 and the intake air. The rotation phase ANG_CAMec (deg.CA) is calculated based on the cam angle signal CAM of the camshaft 115a. Further, it has a function of transmitting the calculated target value TGVTC, the calculated rotation phase ANG_CAMec, and the like to the electric VTC controller 201a by CAN communication.

On the other hand, the electric VTC controller 201a includes a CPU 213, drive circuits 214a and 214b, an internal power supply circuit 215, an input circuit 216, a CAN driver circuit 217, and the like. The power supply terminal and the ground (GND) terminal of the electric VTC controller 201a are connected to the battery VBAT. As a result, power is supplied to the drive circuits 214a and 214b and the internal power supply circuit 215 via the fusible link 219. The internal power supply circuit 215 steps down the voltage of the battery VBAT to generate an internal power supply voltage of, for example, 5V, and supplies it to each circuit in the electric VTC controller 201a including the CPU 213.

The cam angle signal CAM from the cam angle sensor 204 and the crank angle signal POS from the crank angle sensor 203 are input to the input circuit 216 via the input circuit 211 of the ECM201b, and these cam angle signal CAM and the crank angle are input. The signal POS is input to the CPU 213.
The CAN driver circuit 217 is for performing CAN communication between the electric VTC controller 201a and the ECM201b, transmits the transmission information CAN_TX from the CPU 213 to the ECM201b, and receives the reception information CAN_RX from the ECM201b in the CPU 213.

The drive circuits 214a and 214b control energization of the VTC mechanism 114 to the electric motor 12 based on the PWM (Pulse Width Modulation) signals PWM-P and PWP-N output from the CPU 213, respectively. These drive circuits 214a and 214b are provided with current sensors 218a and 218b, respectively, and are adapted to detect the current flowing through the winding of the electric motor 12 and input it to the CPU 213.

FIG. 7 shows the concept of calculating the motor rotation speed using the crank angle signal POS and the cam angle signal CAM. When the phase angle of the cam is constant, the cam rotation speed and half of the engine speed are the same. When the VTC mechanism 114 changes, the phase of the cam changes, so that the rotation speed of the cam and the rotation speed of the engine deviate from each other. In the VTC mechanism 114, since the electric motor 12 produces this deviation, the motor rotation speed can be calculated.
That is, if the rotation speed of the cam and the rotation speed of the engine are known, the motor rotation speed can be calculated, and the motor rotation speed at this time can be obtained by the following equation.
Motor speed = (cam speed- (engine speed / 2)) x reduction ratio

FIG. 8 shows the calculation of the cam rotation speed using the crank angle signal POS and the cam angle signal CAM. The engine speed is calculated from the time from the fall of the crank angle signal POS to the next fall. The cam rotation speed is calculated from the time from the fall to the rise of the cam angle signal CAM. Then, the motor rotation speed is calculated based on the time from the fall to the rise of the cam angle signal CAM and the engine rotation speed, and the estimated value of the motor rotation speed is calibrated.

The fall interval of the crank angle signal POS output from the crank angle sensor 203 is, for example, 10 deg. It is decided in advance by CA, and this 10 deg. The engine speed can be calculated based on how long it took during CA (distance ÷ time). Similarly, on the cam side, the speed can be calculated from "length ÷ time required for signal detection" by using the rising and falling edges of the square wave signal.

With respect to the target angle of the VTC mechanism 114 shown by the alternate long and short dash line in FIG. 8, the real angle connects the changing points of the VTC absolute angle that changes stepwise as shown by the solid line. The response waveform of the VTC angle (= cam phase angle) has an average velocity as shown by the broken line when taken over a long span from the fall of the cam angle signal CAM to the next fall, and matches the target angle. do not do. On the other hand, by calculating the rotation speed of the cam in a short section from the fall to the rise of the cam angle signal CAM and calculating the motor rotation speed from it, the motor rotation speed is calculated accurately and the motor rotation speed is calibrated. can do. As a result, the rotation speed close to the actual angle can be calculated even in the vicinity of the target angle where the error is the largest.

Next, with reference to the functional block diagram of FIG. 9, a specific configuration of the electric VTC controller 201a for calculating the motor rotation speed by using the crank angle signal POS and the cam angle signal CAM described above will be described. The electric VTC controller 201a has a motor torque estimation function (motor torque estimation unit 230), a VTC mechanism model (VTC mechanism model unit 231), a motor rotation speed calibration function (motor rotation speed calibration unit 232), and an integration function (integrator 233). , And a VTC angle calibration function (VTC angle calibration unit 234) and the like.

Then, the motor drive current is input to the motor torque estimation unit 230, and the motor torque (TI characteristic) is estimated based on the physical model of the motor characteristics and parameters such as the torque constant. The estimated motor torque is input to the VTC mechanism model unit 231 to calculate the motor rotation speed based on the physical model of the VTC mechanism 114 and parameters such as moment of inertia, friction and cam torque, and the estimated value of the motor rotation speed is calculated. Input to the motor rotation speed calibration unit 232.

The motor rotation speed calibration unit 232 calculates the cam rotation speed from the length and time from the fall to the rise of the cam angle signal CAM when the cam angle signal CAM rises, and the motor is calculated from the difference between the cam rotation speed and the engine speed. Calculate the rotation speed. Using this calculated motor rotation speed, calibrate the estimated value of the motor rotation speed output from the VTC mechanism model unit 231 (the estimated value of the motor rotation speed calculated based on the motor drive current and the engine operating state is used. It is configured to change to a calculated value based on the cam angle signal CAM and the engine speed).

The corrected estimated value of the motor rotation speed is integrated by the integrator 233 to obtain the VTC angle conversion amount, which is input to the VTC angle calibration unit 234. The VTC angle calibration unit 234 calculates the absolute angle in response to the falling edge of the cam angle signal and calibrates the estimated angle. The estimated angle calibrated from the VTC angle calibration unit 234 is output and fed back to the VTC angle conversion amount.

Next, the calculation of the motor rotation speed will be described in detail with reference to FIG. The motor rotation speed is calculated based on the cam angle signal CAM and the crank angle signal POS, and the estimated value is corrected. Since the difference between the cam rotation speed and the engine rotation speed is the motor rotation speed, more specifically, the motor rotation speed is calculated based on the cam rotation speed and the engine rotation speed, and the estimated value is corrected. The cam rotation speed is calculated from the length and time from the fall to the rise of the cam angle signal. Therefore, the motor rotation speed can be calculated by calculating the motor rotation speed based on the period from the rise to the fall of the cam angle signal and the engine speed and correcting the estimated value.

FIG. 11 is a waveform diagram for explaining an example of the cam angle signal CAM and the calculation of the cam rotation speed. In the present invention, basically, the period Δ1 from the continuous falling edge to the rising edge of the cam angle signal CAM is used. However, the period Δ2 from the fall of the phase angle detection pulse (continuous at equal intervals) in the cam angle signal CAM to the fall of the signal pulse for each cylinder, the period Δ3 until the rise, and even between a plurality of signal pulses. It may be selected and used from the period Δ4 from the falling edge to the next falling edge, the period until the rising edge, or the period Δ5 from the rising edge of the cam angle signal CAM to the falling edge of each cylinder signal.

12A and 12B respectively show a method of calculating the engine speed. As shown in FIG. 12A, the engine speed is calculated for each fall of the crank angle signal POS (10 deg. CA) except for the toothless portion of the crank angle signal POS, and the average value for two times is used (calculation target). ). The cam angle signal CAM is obtained from a falling edge to a rising edge, for example, 20 deg. CA is the calculation target.
The missing tooth portion of the crank angle signal POS can be detected by using, for example, a counter of the crank angle signal POS.

On the other hand, as shown in FIG. 12B, when the rising edge of the cam angle signal CAM overlaps with the missing tooth portion of the crank angle signal POS, the calculated value at the falling edge of the crank angle signal POS after the missing tooth of the crank angle signal POS is calculated. Use. That is, at the rise of the cam angle signal CAM (in this example, 20 deg. CA from the fall of the cam angle signal CAM) and then the fall of the crank angle signal POS (for example, 30 deg. CA after the fall of the crank angle signal POS). , Calculate and calibrate the motor rotation speed. In this way, by aligning the lengths of the cam rotation speed and the calculation target of the engine rotation speed, the calculation accuracy of the motor rotation speed can be ensured.
At the time of this calculation, only the latest value may be used for the engine speed, but the latest value and the average value may be switched according to the behavior of the engine speed. When the engine speed is constant, accuracy can be ensured even if the latest value is used.

13A and 13B show the timing of calculation and calibration of the motor rotation speed, respectively. The calculation and correction of the motor rotation speed are performed at the rise of the cam angle signal CAM or the fall of the crank angle signal POS after the rise of the cam angle signal CAM. This execution timing is determined based on the positional relationship between the rising edge of the cam angle signal CAM and the falling edge of the crank angle signal POS. In this way, the calculation accuracy of the motor rotation speed can be ensured by calculating the motor rotation speed from the calculated values in which the cam rotation speed and the update timing of the engine rotation speed are close to each other.

As shown in FIG. 13A, when the period from the fall of the previous crank angle signal POS to the rise of the cam angle signal CAM is short, after updating the engine speed, the cam rotates at the rise of the cam angle signal CAM. The motor rotation speed is calculated and calibrated at the timing when the speed is calculated. The positional relationship between the rise of the cam angle signal CAM and the fall of the crank angle signal POS is determined from the time t1 from the fall of the crank angle signal POS to the rise of the cam angle signal CAM and the period Δt of the previous crank angle signal POS. To do.
Then, when the time t1 from the fall of the crank angle signal POS to the rise of the cam angle signal CAM is less than half of the period Δt of the previous crank angle signal POS, the cam rotation speed is calculated by the rise of the cam angle signal CAM. Then, the motor rotation speed is calculated and corrected.

On the other hand, as shown in FIG. 13B, when the period from the fall of the previous crank angle signal POS to the rise of the cam angle signal CAM is long and the next update is closer, the rise of the cam angle signal CAM After calculating the cam rotation speed, wait until the next update of the engine speed, and then calculate and calibrate the motor speed at this timing. That is, when the time t2 from the fall of the crank angle signal POS to the rise of the cam angle signal CAM is half or more of the period Δt of the previous crank angle signal POS, the crank angle after the rise of the cam angle signal CAM The engine speed is calculated at the fall of the signal POS, and the motor speed is calculated and corrected.

Regarding this determination, the positional relationship between the rise of the cam angle signal CAM and the fall of the crank angle signal POS is the time from the fall of the crank angle signal POS to the rise of the cam angle signal CAM (t1 or t2) and the previous crank. It is determined from the period Δt of the angular signal POS.

The motor rotation speed may be calculated and calibrated without determining the timing of the cam angle signal CAM and the crank angle signal POS as described above. When the engine speed is constant, accuracy can be ensured without considering the timing.
Further, it may be carried out at a predetermined time interval (ms). As for the fall timing of the crank angle signal POS and the rise timing of the cam angle signal CAM, the interval becomes narrower and an interrupt is inserted when the engine rotation is faster, and the interrupt is inserted slowly when the engine rotation is lower. Therefore, as the engine speed increases, interrupts increase and the calculation load increases. Therefore, by doing so, it is possible to suppress an increase in the calculation load due to an increase in interrupts.

FIG. 14 shows the correction of the estimated value of the rotation speed of the motor. The correction of the estimated value of the motor rotation speed is performed by replacing (calibrating) the estimated value of the motor rotation speed with the calculated value. As shown in FIG. 14, by performing calibration in response to the rise of the cam angle signal CAM, it is possible to correct the estimated value of the motor rotation speed and bring it closer to the actual value. As a result, the amount of erroneous calculation of the motor rotation speed estimated value can be reduced, and the accuracy of the angle estimated value can be improved.
The estimated value of the motor rotation speed this time may be corrected based on the calculated value of the motor rotation speed and the estimated value up to the previous calculation. For example, the estimated value of the motor rotation speed this time is replaced with the average value of the value calculated by the cam angle signal CAM and the previously estimated value.

FIG. 15 is a waveform diagram for explaining learning of the period (length) from the fall to the rise of the cam angle signal CAM. The period (time) from the fall to the rise of the cam angle signal CAM may differ due to manufacturing variations of the cam angle sensor 204 and the like. Therefore, when the engine speed and the phase angle of the cam are constant, the length is learned based on the target time and the engine speed. By learning the variation of the cam angle signal CAM and correcting the calculated value in this way, it is possible to secure the calculation accuracy of the cam rotation speed and the motor rotation speed.

As a calculation method, it is assumed that the length from the fall to the rise of the cam angle signal CAM is ΔL, the time from the fall to the rise of the cam angle signal CAM is Tt, the cam rotation speed is Cr, and the engine speed is Er. , Cam rotation speed Cr
Cr = ΔL ÷ Tt
When the phase angle of the cam is constant
Cr = Er ÷ 2
Therefore, the length ΔL from the fall to the rise of the cam angle signal CAM is
ΔL = (Er ÷ 2) × Tt
Will be.

FIG. 16 is a waveform diagram for explaining the calculation and correction of the motor rotation speed according to the engine speed. As the engine speed increases, the frequency of inputting the cam angle signal CAM increases, so that the frequency of calculating the motor rotation speed increases, and the calculation load increases. Therefore, it is preferable to stop the calculation and correction of the motor rotation speed according to the engine speed (when the engine speed becomes high). As a result, interrupts when the engine is rotating at high speed can be reduced, and the calculation load can be reduced.

Alternatively, the calculation and correction of the motor rotation speed may be thinned out (reduced) according to the engine speed. For example, as shown by the downward arrow in FIG. 16, when the motor rotation speed is equal to or less than the predetermined rotation speed, the motor rotation speed is calculated and corrected in response to the rise of each cam angle signal CAM (including the pulse signal for cylinder discrimination). At a predetermined rotation speed or higher, the motor rotation speed is calculated and corrected every time the cam angle signal rises a predetermined number of times.
Further, the calculation may be corrected according to the engine speed.

FIG. 17 shows a simulation result comparing the difference between the actual angle and the estimated angle of the VTC mechanism 114 in the conventional invention and the present invention, and FIG. 18 is an enlarged view of the region 300 surrounded by the broken line in FIG.
Conventionally, the motor rotation speed has not been calibrated, and only the estimated VTC angle has been corrected in response to the fall of the cam angle signal CAM as shown by the broken line. That is, the absolute angle of the VTC angle is calculated at the fall of the cam angle signal CAM, and the estimated angle is calibrated with the absolute angle. Since the motor rotation speed is estimated based on the physical model and parameters, it does not always match the actual one and an error occurs, and as shown by arrow A2 in FIG. 18, the deviation of the estimated angle from the actual angle of the VTC mechanism 114 is large. It was getting bigger.

On the other hand, in the present invention, in addition to the above-mentioned correction of the estimated VTC angle, the motor rotation speed is calculated in response to the rise of the cam angle signal CAM, and the estimated value of the motor rotation speed is shown by the solid line. Is calibrating. As a result, the deviation of the estimated value of the VTC angle due to the error of the motor rotation speed can be corrected for each rise of the cam angle signal CAM. Therefore, as shown by the arrow A1, the deviation of the estimated angle with respect to the actual angle of the VTC mechanism 114 can be corrected. Can be reduced.

FIG. 19A shows a simulation result comparing the VTC angle between the conventional method and the present invention, and FIG. 19B shows a simulation result comparing the operating voltage between the conventional method and the present invention. 20A is an enlarged view of the area 310 surrounded by the broken line in FIG. 19A, and FIG. 20B is an enlarged view of the area 320 surrounded by the broken line in FIG. 19B.
As described above, the error in the operating voltage can be reduced by reducing the deviation of the estimated angle from the actual angle of the VTC mechanism 114. The operating voltage calculated from the actual angle is shown by a solid line in FIGS. 19B and 20B, and the operating voltage calculated from no calibration of the estimated angle (conventional) is shown by a broken line. In addition, the operating voltage calculated from the calibration of the estimated angle (in the present invention) is shown by a solid line.

As shown by comparing the arrows A1 and A2, according to the present invention, since the operating voltage is calculated from the estimated angle by feedback control, the deviation of the estimated angle from the actual angle can be reduced. As a result, it is possible to reduce the application of an inaccurate operating voltage to the VTC mechanism. As a result, the erroneous operating voltage can be reduced, and the operating voltage can be made closer to the operating voltage calculated from the actual angle as compared with the conventional case. Therefore, the convergence of the VTC mechanism with respect to the target angle can be improved, and deterioration of vehicle performance can be suppressed.

12 ... Electric motor, 100 ... Internal combustion engine (engine), 114 ... VTC mechanism, 201 ... Control device, 201a ... Electric VTC controller, 201b ... Engine control module (ECM), 201c ... CAN, 203 ... Crank angle sensor, 204 ... Cam angle sensor, 205 ... Ignition switch, 230 ... Motor torque estimation unit, 231 ... VTC mechanism model unit, 232 ... Motor rotation speed calibration unit, 233 ... Integrator, 234 ... VTC angle calibration unit, CAM ... Cam angle signal, POS … Crank angle signal

Claims (14)

1. In a control device of a variable valve timing mechanism including a controller that detects a cam phase angle based on a cam angle signal and controls a cam phase angle using an electric motor.
   The controller
   When the cam angle signal is detected, the phase angle of the cam when the previous cam angle signal is detected is updated, and the motor drive current and the engine operating state are updated during the detection of the phase angle of the cam. Calculate the motor rotation speed based on and
   The motor rotation angle is calculated based on the motor rotation speed to estimate the phase angle of the cam.
   Interpolating the phase angle of the cam from the motor rotation angle
   The estimated value of the motor rotation speed calculated based on the motor drive current and the engine operating state is changed to a calculated value based on the cam angle signal and the engine rotation speed.
   A control device for a variable valve timing mechanism that is configured as such.
2. The control device for the variable valve timing mechanism according to claim 1, wherein the controller is further configured to correct an estimated value of the motor rotation speed with a calculated value based on a cam rotation speed and an engine rotation speed.
3. The controller is further configured to replace the estimated value of the motor rotation speed with a calculated value calculated based on the period from the fall to the rise of the cam angle signal and the engine speed. The control device of the variable valve timing mechanism described in 1.
4. The controller is further configured to correct the estimated value of the motor rotation speed this time based on the calculated value calculated using the cam angle signal and the estimated value of the motor rotation speed up to the previous calculation. The control device for the variable valve timing mechanism according to claim 1.
5. The cam angle signal includes a phase angle detection pulse and a signal pulse for each cylinder, and the controller is further configured to be used by selecting from a falling to rising period between a plurality of signal pulses. The control device for the variable valve timing mechanism according to claim 1.
6. The control device for a variable valve timing mechanism according to claim 1, wherein the controller learns a period from a fall to a rise of the cam angle signal and is further configured to calibrate when calculating the motor rotation speed. ..
7. The control device for the variable valve timing mechanism according to claim 1, wherein the controller is further configured to stop the correction of the motor rotation speed according to the engine speed.
8. In the control method of the variable valve timing mechanism that detects the phase angle of the cam based on the cam angle signal and controls the phase angle of the cam using an electric motor.
   When the cam angle signal is detected, the phase angle of the cam when the previous cam angle signal is detected is updated, and the motor drive current and the engine operating state are updated during the detection of the phase angle of the cam. To calculate the motor rotation speed based on
   The motor rotation angle is calculated based on the motor rotation speed to estimate the phase angle of the cam.
   Interpolating the phase angle of the cam from the motor rotation angle and
   A control method for a variable valve timing mechanism, which comprises changing an estimated value of a motor rotation speed calculated based on the motor drive current and an engine operating state to a calculated value based on the cam angle signal and the engine rotation speed. ..
9. The control method for the variable valve timing mechanism according to claim 8, further comprising correcting the estimated value of the motor rotation speed with a calculated value based on the cam rotation speed and the engine rotation speed.
10. The variable valve timing according to claim 8, further comprising replacing the estimated value of the motor rotation speed with a calculated value calculated based on the period from the fall to the rise of the cam angle signal and the engine speed. How to control the mechanism.
11. The eighth aspect of the present invention further comprises correcting the estimated value of the motor rotation speed this time based on the calculated value calculated by using the cam angle signal and the estimated value of the motor rotation speed up to the previous calculation. The method of controlling the variable valve timing mechanism described.
12. The cam angle signal includes a phase angle detection pulse and a signal pulse for each cylinder, and the controller is further provided to be used by selecting from a falling to rising period between a plurality of signal pulses. Item 8. The control method of the variable valve timing mechanism according to Item 8.
13. The control method of the variable valve timing mechanism according to claim 8, further comprising learning the period from the fall to the rise of the cam angle signal and calibrating it at the time of calculating the motor rotation speed.
14. The control method of the variable valve timing mechanism according to claim 8, further comprising stopping the correction of the motor rotation speed according to the engine speed.

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