JP2008088928A - Variable valve timing control device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve both of excellent starting characteristics and stability in idling operation in an engine equipped with a variable valve timing mechanism for adjusting the opening/closing timing of an intake valve. <P>SOLUTION: This variable valve timing control device is provided with a torsion coil spring (an advance energizing spring) 110 advancing the rotation phase of an intake camshaft 12 against the cam torque of the intake camshaft 21, and a motor-driven oil pump (a sub-oil pump) 20 assisting oil pressure supplied to the variable valve timing mechanism 100. When starting the engine 1, the opening/closing timing of the intake valve 13 is held into a predetermined advance position by the energizing force of the torsion coil spring 110. An actual compression ratio in starting is thereby improved to secure excellent starting characteristics. During idling operation after the start of the engine, the motor-driven oil pump 20 is driven to delay the opening/closing timing of the intake valve 13 with respect to the starting advance position. Valve overlap is thereby reduced to secure stable idling operation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a variable valve timing control device for an internal combustion engine that controls opening / closing timing of an engine valve of the internal combustion engine in accordance with an engine operating state.

  In an internal combustion engine (hereinafter also referred to as an engine) mounted on a vehicle or the like, rotation of a crankshaft is transmitted to a camshaft via a timing belt or the like. The engine valve (intake valve / exhaust valve) of the engine is periodically pushed down by the cam of the camshaft and reciprocates to open and close the intake passage and the exhaust passage. In this type of engine, the rotational phase of the camshaft relative to the crankshaft is always constant. On the other hand, in recent years, a variable valve timing (VVT: Variable Valve Timing) mechanism is mounted on the engine (see, for example, Patent Documents 1 and 2). The variable valve timing mechanism is a mechanism for changing the opening / closing timing of the engine valve by changing the rotational phase of the camshaft relative to the crankshaft for the purpose of improving engine output, improving fuel consumption, and reducing exhaust emissions.

Examples of the variable valve timing mechanism include a helical spline type and a vane type mechanism. Among these, the vane type variable valve timing mechanism includes, for example, a vane housing having a recess formed on the inner peripheral surface and two recesses in the vane housing (a retarded-side hydraulic chamber and an advanced-side hydraulic chamber). A vane rotor having vanes partitioned into a vane rotor, a vane housing connected to a crankshaft via a timing belt or the like, and the vane rotor connected to a camshaft, the retard angle side hydraulic chamber and the advance angle side hydraulic chamber By controlling the hydraulic pressure to be supplied by an oil control valve (OCV), the opening / closing timing of the engine valve is continuously changed by shifting the rotational phase of the crankshaft and the camshaft.
JP 2002-227621 A JP-A-10-68306

  Incidentally, at the time of starting the engine, it is desirable to make the intake valve closing timing earlier in order to increase the actual compression ratio and ensure good startability. On the other hand, during idle operation, it is desirable to reduce the valve overlap between the intake valve and the exhaust valve in order to ensure a stable engine operation state. However, in the conventional variable valve timing control device, the rotational phase at the engine start and the idling operation is set to the same phase, so that both conditions suitable for starting and conditions suitable for idling are satisfied. I can't. For this reason, in the past, it was necessary to make a compromise between engine startup and idle operation.

  Here, with respect to improving the startability of the engine, in Patent Documents 1 and 2 described above, an advance angle assist spring (advance angle biasing spring) for advancing the rotational phase of the intake camshaft is provided in the variable valve timing mechanism. It is described that the opening / closing timing of the intake valve is held at the advance position at the start. However, when the method of holding the advance angle state at the start by the advance angle assist spring is adopted, it is difficult to perform the retard angle control during the idle operation after the start. In other words, when the engine speed is in the low speed range, such as during idle operation, the discharge pressure of the mechanical oil pump driven by the engine rotation is low, so variable valve timing against the urging force of the advance assist spring. The hydraulic pressure required to retard the mechanism cannot be obtained, and it is difficult to perform reliable retardation control.

  The present invention has been made in view of such circumstances, and in an internal combustion engine having a variable valve timing mechanism that makes the intake valve opening and closing timing variable, both good startability and stability during idle operation are achieved. An object of the present invention is to provide a variable valve timing control device for an internal combustion engine that can be realized.

  The present invention relates to a hydraulically driven variable valve timing mechanism that adjusts the opening / closing timing of an intake valve by changing the rotational phase of an intake camshaft with respect to a crankshaft of the internal combustion engine, and mechanical oil driven by the rotation of the internal combustion engine In a variable valve timing control device comprising a pump and hydraulic control means (for example, an oil control valve) for controlling the hydraulic pressure supplied from the mechanical oil pump to the variable valve timing mechanism, the variable valve timing control device resists the cam torque of the intake camshaft. An advance bias spring for advancing the rotational phase of the intake camshaft and a sub oil pump driven by power other than the rotation of the internal combustion engine, and at the start of the internal combustion engine, the advance bias The opening and closing timing of the intake valve is held at a predetermined advance position by the biasing force of the spring, During idling after start of the engine, the drives the sub oil pump, the closing timing of the intake valve, is characterized in that retarded relative to the advance position at the start.

  An example of the sub oil pump that is driven by power other than the rotation of the internal combustion engine is an electric oil pump.

  According to the present invention, an advance bias spring that advances the rotational phase of the intake camshaft against the cam torque of the intake camshaft, and a variable valve timing mechanism that is driven by power other than the rotation of the internal combustion engine. Since the sub oil pump for assisting the hydraulic pressure is provided, it is possible to achieve both good startability of the internal combustion engine and stability during idling. This point will be described below.

  First, in the present invention, an advance biasing spring (for example, a torsion coil) that advances the rotational phase of the intake camshaft against the cam torque of the intake camshaft is added to a variable valve timing mechanism that makes the intake valve open / close timing variable. When the internal combustion engine is started, the opening / closing timing of the intake valve is held at a predetermined advance position (for example, the most advanced position) by the urging force of the advance urging spring, and the closing timing of the intake valve is advanced. As a result, the actual compression ratio at the start of the internal combustion engine is increased to ensure good startability.

  Next, during idle operation after start-up, retard angle control is performed to reduce the valve overlap between the intake valve and the exhaust valve, but an advance bias spring is provided to advance the rotation phase of the intake camshaft. In order to perform retard control in the variable valve timing mechanism, it is necessary to apply a hydraulic pressure larger than the difference between the bias force of the advance bias spring and the cam torque of the intake camshaft to the retard side pressure chamber of the variable valve timing mechanism. There is. However, during idle operation, since the discharge pressure of the mechanical oil pump (pump driven by the rotation of the internal combustion engine) is low, the variable valve timing mechanism cannot be retarded.

  Therefore, in the present invention, a sub oil pump (for example, an electric oil pump) driven by power other than the rotation of the internal combustion engine is provided, and the hydraulic pressure supplied to the variable valve timing mechanism is driven by driving the sub oil pump during idle operation. By making it higher, it is possible to achieve retard control during idle operation. Such retard control makes it possible to eliminate valve overlap between the intake valve and the exhaust valve during idle operation, thereby ensuring a stable idle operation state.

  In the present invention, the sub oil pump is driven during the stop operation of the internal combustion engine (between the ignition switch is turned off and the rotation of the engine is completely stopped) to advance the opening / closing timing of the intake valve to a predetermined advance position. You may do it. With this advance angle control during the stop operation, the intake valve opening and closing timing can be reliably controlled to a predetermined advance angle position (for example, the most advanced angle position). The internal combustion engine can be started with the timing held at a predetermined advance position.

  According to the present invention, an advance bias spring that advances the rotational phase of the intake camshaft against the cam torque of the intake camshaft, and a variable valve timing mechanism that is driven by power other than the rotation of the internal combustion engine. And a sub oil pump for assisting the hydraulic pressure to maintain the intake valve opening / closing timing at a predetermined advance position by the urging force of the advance urging spring at the start of the internal combustion engine. Since the oil pump is driven so that the opening and closing timing of the intake valve is retarded with respect to the advance position at the start, both good startability and stability during idle operation can be realized. it can.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  First, an engine (internal combustion engine) to which the variable valve timing control device of the present invention is applied will be described.

-Engine-
FIG. 1 is a diagram showing a schematic configuration of an engine to which a variable valve timing control device of the present invention is applied. FIG. 1 shows only the configuration of one cylinder of the engine.

  The engine 1 is a port injection type multi-cylinder gasoline engine mounted on a vehicle, and a piston 1c that reciprocates in a vertical direction is provided in a cylinder block 1a constituting each cylinder. The piston 1c is connected to the crankshaft 15 via the connecting rod 16, and the reciprocating motion of the piston 1c is converted into rotation of the crankshaft 15 by the connecting rod 16. The crankshaft 15 of the engine 1 is connected to the transmission.

  A signal rotor 17 is attached to the crankshaft 15. A plurality of protrusions (teeth) 17a... 17a are provided on the outer peripheral surface of the signal rotor 17 at equal angles. A crank position sensor (engine speed sensor) 37 is disposed near the side of the signal rotor 17. The crank position sensor 37 is, for example, an electromagnetic pickup, and generates a pulsed signal (output pulse) corresponding to the protrusion 17a of the signal rotor 17 when the crankshaft 15 rotates.

  A water temperature sensor 31 for detecting the cooling water temperature is disposed in the cylinder block 1 a of the engine 1. A cylinder head 1b is provided at the upper end of the cylinder block 1a, and a combustion chamber 1d is formed between the cylinder head 1b and the piston 1c. A spark plug 3 is disposed in the combustion chamber 1 d of the engine 1. The ignition timing of the spark plug 3 is adjusted by the igniter 4. The igniter 4 is controlled by an ECU (electronic control unit) 300.

  An oil pan 1e for storing lubricating oil is provided below the cylinder block 1a of the engine 1. The lubricating oil stored in the oil pan 1e is pumped up by a mechanical oil pump 19 through an oil strainer 18 (see FIG. 2) that removes foreign matters when the engine 1 is operated, and the piston 1c, the crankshaft 15, It is supplied to the connecting rod 16 and used for lubrication and cooling of each part. Then, the lubricating oil supplied in this way is used for lubrication and cooling of each part of the engine 1, then returned to the oil pan 1 e, and again in the oil pan 1 e until it is pumped up by the mechanical oil pump 19. Stored. In this example, the lubricating oil stored in the oil pan 1e is also used as hydraulic oil for a variable valve timing mechanism (hereinafter referred to as VVT) 100 described later. The mechanical oil pump 19 is driven by the rotation of the crankshaft 15 of the engine 1.

An intake passage 11 and an exhaust passage 12 are connected to the combustion chamber 1 d of the engine 1. The intake passage 11 includes an air cleaner 7, a hot-wire air flow meter 32, an intake air temperature sensor 33 (built in the air flow meter 32), an electronically controlled throttle valve 5 for adjusting the intake air amount of the engine 1, and the like. Has been placed. The throttle valve 5 is driven by a throttle motor 6. The opening degree of the throttle valve 5 is detected by a throttle position sensor 36. In the exhaust passage 12 of the engine 1, an O ₂ sensor 34 for detecting the oxygen concentration in the exhaust gas, the three-way catalyst 8, and the like are arranged.

  An intake valve 13 is provided between the intake passage 11 and the combustion chamber 1d. By opening and closing the intake valve 13, the intake passage 11 and the combustion chamber 1d are communicated or blocked. Further, an exhaust valve 14 is provided between the exhaust passage 12 and the combustion chamber 1d. By opening and closing the exhaust valve 14, the exhaust passage 12 and the combustion chamber 1d are communicated or blocked. The opening / closing drive of the intake valve 13 and the exhaust valve 14 is performed by each rotation of the intake camshaft 21 and the exhaust camshaft 22 to which the rotation of the crankshaft 15 is transmitted via a timing belt or the like. A VVT 100 is provided at the end of the intake camshaft 21. The structure of the VVT 100 will be described later.

  A cam position sensor 38 is disposed in the vicinity of the intake camshaft 21. The cam position sensor 38 is, for example, an electromagnetic pickup, and is disposed so as to face one protrusion on the outer peripheral surface of the rotor that is integrally provided on the intake camshaft 21, and when the intake camshaft 21 rotates. Outputs a pulse signal. Since the intake camshaft 21 (exhaust camshaft 22) rotates at a half rotational speed of the crankshaft 15, the cam position sensor 38 generates one pulse signal each time the crankshaft 15 rotates 720 °. Is generated.

  A fuel injection injector (fuel injection valve) 2 is disposed in the intake passage 11. Fuel of a predetermined pressure is supplied from the fuel tank to the injector 2 by a fuel pump, and the fuel is injected into the intake passage 11. This injected fuel is mixed with intake air to form an air-fuel mixture and introduced into the combustion chamber 1 d of the engine 1. The air-fuel mixture (fuel + air) introduced into the combustion chamber 1d is ignited by the spark plug 3 and combusted / exploded. The piston 1c reciprocates due to combustion / explosion of the air-fuel mixture in the combustion chamber 1d, and the crankshaft 15 rotates. The operation state of the engine 1 is controlled by the ECU 300.

-VVT-
The VVT 100 is a mechanism that varies the rotational phase of the intake camshaft 21 with respect to the crankshaft 15 of the engine 1. As shown in FIGS. 2 and 3, the VVT 100 has a substantially hollow disk-shaped vane housing 101 and the vane housing 101. A vane rotor 104 rotatably accommodated therein is provided. A plurality (four in this example) of vanes 105 are integrally formed on the vane rotor 104. The vane rotor 104 is fixed to the intake camshaft 21 by a center bolt 106 and rotates integrally with the intake camshaft 21.

  The front side of the vane housing 101 is covered with a front cover 107. The vane housing 101 and the front cover 107 are fixed to the timing pulley 109 with bolts 108, and the vane housing 101 and the front cover 107 rotate integrally with the timing pulley 109. The timing pulley 109 is connected to the crankshaft 15 via a timing belt.

  Further, the VVT 100 of this example is provided with a torsion coil spring (advance biasing spring) 110 that advances the rotational phase of the intake camshaft 21 against the cam torque at the start of the intake camshaft 21. . The torsion coil spring 110 is accommodated in a spring guide 107 a formed integrally with the front cover 107. One end of the torsion coil spring 110 is locked to a locking pin 107 b fixed to the front cover 107, and the other end is locked to the vane rotor 104. The cam torque of the intake camshaft 21 is torque generated due to the reaction force of the valve spring of the intake valve 13 and the dragging torque of the journal.

  Next, each part of the VVT 100 will be described.

  First, the same number of convex portions 102 as the vanes 105 of the vane rotor 104 are formed inside the vane housing 101, and the vanes 105 of the vane rotor 104 are accommodated in the concave portions 103 formed between the convex portions 102. ing. The front end surface of each vane 105 is slidably in contact with the inner peripheral surface of the recess 103. The vane rotor 104 rotates relative to the vane housing 101 by receiving the pressure of the hydraulic oil by the vane 105. Due to this relative rotation, the rotational phase of the intake camshaft 21 with respect to the crankshaft 15 changes.

  In each recess 103 of the vane housing 101, two spaces defined by the vanes 105 of the vane rotor 104 are formed. Of these two spaces, the space behind the vane 105 in the camshaft rotation direction (in the direction of the arrow in FIG. 3) forms the advance side hydraulic chamber 111, and the front space in the camshaft rotation direction is delayed. A corner side hydraulic chamber 112 is configured.

  A stepped through hole 114 is formed in one of the vanes 105 of the vane rotor 104. A lock pin 113 with a flange is slidably accommodated in the through hole 114. The lock pin 113 is biased toward the timing pulley 109 by the elastic force of the compression coil spring 115. On the other hand, the timing pulley 109 is formed with a locking hole 116 at a position corresponding to the lock pin 113, and when the lock pin 113 is aligned with the locking hole 116 due to relative rotation of the vane rotor 104, the compression coil spring 115. The lock pin 113 protrudes due to the elastic force, and the tip of the lock pin 113 enters the locking hole 116.

  The relative rotation of the vane rotor 104 with respect to the vane housing 101 is restricted by the entry of the lock pin 113 into the locking hole 116, and the intake camshaft 21 and the timing pulley 109 are maintained in a state where the relative rotation phase in the restricted state is maintained. And rotate together. In this example, the lock pin 113 and the locking hole 116 are configured to coincide with each other when the lock phase, that is, the rotation phase of the intake camshaft 21 becomes the most advanced angle phase.

  In order to unlock the lock pin 113, an oil passage 117 is provided in the vane 105 having the lock pin 113. The oil passage 117 communicates with the advance side hydraulic chamber 111 and the locking hole 116, and the hydraulic pressure supplied to the advance side hydraulic chamber 111 is introduced into the locking hole 116. An annular oil space 118 is formed between the flange portion of the lock pin 113 and the step portion of the through hole 114. The annular oil space 118 communicates with the retarded-side hydraulic chamber 112 through the oil passage 119, and the hydraulic pressure supplied to the retarded-side hydraulic chamber 112 is also introduced into the annular oil space 118. When the hydraulic pressure in the locking hole 116 or the annular oil space 118 overcomes the urging force of the compression coil spring 115, the lock pin 113 is released from the locking hole 116, and the locking of the lock pin 113 is released. By releasing the lock pin 113, relative rotation between the vane housing 101 and the vane rotor 104 is allowed, and based on the hydraulic pressure supplied to the advance side hydraulic chamber 111 and the retard side hydraulic chamber 112, The rotational phase of the vane rotor 104 with respect to the vane housing 101 can be adjusted.

  In the VVT 100 having the above structure, the vane rotor 104 rotates relative to the vane housing 101 by the respective hydraulic pressures in the advance side hydraulic chamber 111 and the retard side hydraulic chamber 112. That is, when the hydraulic pressure in the advance hydraulic chamber 111 is made higher than the hydraulic pressure in the retard hydraulic chamber 112, the vane rotor 104 rotates relative to the vane housing 101 in the rotation direction of the intake camshaft 21. At this time, the rotational phase of the intake camshaft 21 is advanced with respect to the rotational phase of the crankshaft 15 (advance angle). On the other hand, when the hydraulic pressure in the retarded-side hydraulic chamber 112 is made higher than the hydraulic pressure in the advanced-side hydraulic chamber 111, the vane rotor 104 is relative to the vane housing 101 in the direction opposite to the rotation direction of the intake camshaft 21. The rotation phase of the intake camshaft 21 is delayed with respect to the rotation phase of the crankshaft 15 (retard angle). The valve timing of the intake valve 13 can be made variable by adjusting the rotational phase.

  Next, the configuration of a hydraulic control system that controls the pressure of hydraulic fluid supplied to the advance side hydraulic chamber 111 and the retard side hydraulic chamber 112 will be described with reference to FIG.

  First, in the cylinder head 1b, the intake camshaft 21, the vane rotor 104, and the like, an advance side passage 121 that communicates with the advance side hydraulic chamber 111 and a retard side passage 122 that communicates with the retard side hydraulic chamber 112 are formed. Has been. An oil control valve (hereinafter referred to as OCV) 200 is connected to the advance side passage 121 and the retard side passage 122. An oil supply passage 131 and an oil discharge passage (drain passage) 132 are connected to the OCV 200. The oil supply passage 131 is connected to an electric oil pump 20 that is driven by electric power from a battery or the like mounted on the vehicle. The oil supply passage 131 is connected to a bypass passage 133 that bypasses the electric oil pump 20. A check valve (one-way valve) 134 is provided in the bypass passage 133.

  The suction port of the electric oil pump 20 communicates with the inside of the reserve tank 140. The reserve tank 140 is supplied with lubricating oil (hydraulic oil) pumped from the oil pan 1 e by the mechanical oil pump 19 described above. The reserve tank 140 is a simple sealed tank, and when the electric oil pump 20 is not driven, the hydraulic oil pumped up by the mechanical oil pump 19 from the oil pan 1e is stored in the reserve tank 140 and the bypass passage 133 (reverse). It is supplied to the OCV 200 through the stop valve 134). When the electric oil pump 20 is driven, a hydraulic pressure obtained by adding the hydraulic pressure of the electric oil pump 20 to the hydraulic pressure of the mechanical oil pump 19 is supplied to the OCV 200. In this example, the electric oil pump 20 is driven in “after start / idle operation” and “during stop operation” which will be described later, but it is necessary to increase the hydraulic pressure supplied to the OCV 200 even during normal operation. In some cases, the electric oil pump 20 is driven to assist the hydraulic pressure. In some cases, only the electric oil pump 20 is driven while the mechanical oil pump 19 is stopped.

  The OCV 200 is a four-port three-position switching valve that drives a spool valve by an electromagnetic solenoid 201 and a compression coil spring 202. The OCV 200 controls the position of the spool valve to apply hydraulic pressure to the advance side passage 121 (advance side hydraulic chamber 111). Select a position to supply, a position to supply hydraulic pressure to the retard side passage 122 (retard side hydraulic chamber 112), or a position to supply no hydraulic pressure to either the advance side passage 121 or the retard side passage 122 It is designed to switch. The voltage applied to the electromagnetic solenoid 201 of the OCV 200 is duty-controlled by the ECU 300, and the rotational phase of the vane rotor 104 can be arbitrarily adjusted in the range from the most advanced angle phase to the most retarded angle phase by the duty control. In this example, when the energization of the electromagnetic solenoid 201 is stopped (at 0 duty), the spool valve is set to a position for supplying hydraulic pressure to the advance side passage 121 by the elastic force of the compression coil spring 202.

-ECU-
The ECU 300 includes a CPU 301, a ROM 302, a RAM 303, a backup RAM 304, and the like as shown in FIG. The ROM 302 stores various control programs, maps that are referred to when the various control programs are executed, and the like. The CPU 301 executes arithmetic processing based on various control programs and maps stored in the ROM 302. A RAM 303 is a memory for temporarily storing calculation results in the CPU 301 and data input from each sensor. A backup RAM 304 is a non-volatile memory for storing data to be saved when the engine 1 is stopped. is there. These ROM 302, CPU 301, RAM 303, and backup RAM 304 are connected to each other via a bus 307 and are also connected to an input interface 305 and an output interface 306.

The input interface 305 includes a water temperature sensor 31, an air flow meter 32, an intake air temperature sensor 33, an O ₂ sensor 34, an accelerator position sensor 35 that detects the accelerator opening, a throttle position sensor 36, a crank position sensor 37, a cam position sensor 38, Various sensors such as a shift position sensor 39 for detecting the operation position of the shift lever of the transmission are connected. Connected to the output interface 306 are the injector 2, the igniter 4 of the spark plug 3, the throttle motor 6 of the throttle valve 5, the OCV 200, the electric oil pump 20, and the like.

  The ECU 300 executes various controls of the engine 1 including the injection timing control of the injector 2 and the ignition timing control of the spark plug 3 based on the detection signals of the various sensors described above. Further, the ECU 300 executes the control of the VVT 100 (OCV 200) and the control of the electric oil pump 20 including the following "control at stop / start", "control after start / idle operation", and "control during stop operation". .

-Control at stop and start-
When the engine 1 is stopped or started, the opening / closing timing of the intake valve 13 is set to the most advanced position (FIG. 5A) by the biasing force of the torsion coil spring 110, and the most advanced position is set by the lock pin 113. It is mechanically locked. Therefore, when the engine is started, the engine 1 can be started in a state where the opening / closing timing (closing timing) of the intake valve 13 is held at the most advanced position, so that the actual compression ratio at the time of starting can be increased, which is favorable. Startability can be ensured. If the closing timing of the intake valve 13 is made earlier, the valve overlap between the intake valve 13 and the exhaust valve 14 increases. However, when the engine 1 is started, the negative pressure of the intake pipe is small. There is no problem.

-After startup / idle operation-
When the engine 1 is started and the operation state of the engine 1 is stabilized (after the start), the electric oil pump 20 is driven quickly and the OCV 200 is controlled to retard the opening / closing timing of the intake valve 13. Specifically, by driving the electric oil pump 20, hydraulic pressure is supplied to the retard side pressure chamber 112 of the VVT 100 to release the advance lock by the lock pin 113 and at the same time retard the rotation phase of the intake camshaft 21; As shown in FIG. 5B, retard control is performed to retard the opening / closing timing of the intake valve 13 by a predetermined retard amount with respect to the most advanced position. At this time, immediately after the engine 1 is started, even if the discharge pressure of the mechanical oil pump 19 is low, the hydraulic pressure of the electric oil pump 20 is applied, so the intake camshaft 21 resists the biasing force of the torsion coil spring 110. It is possible to reliably retard the rotation phase of the engine, and by such retardation control, it is possible to eliminate the valve overlap between the intake valve 13 and the exhaust valve 14 and to ensure stability during idle operation. can do.

-During normal operation-
The OCV 200 is driven in accordance with the operating state of the engine 1 to perform advance / retard angle control of the VVT 100, thereby setting an appropriate opening / closing timing of the intake valve 13 in accordance with the operating state of the engine 1. When the throttle valve 5 is fully closed when the vehicle is stopped or the like, and the engine 1 shifts from the normal operation state to the idle operation, the control during the idle operation, that is, the opening / closing timing of the intake valve 13 is set with respect to the most advanced position. Then, control for retarding by a predetermined retard amount (FIG. 5B) is performed.

-Control during stop operation-
During the stop operation of the engine 1 (between the ignition switch is turned off and the rotation of the engine 1 is completely stopped), the oil pressure is supplied to the advance side passage 121 (advance side hydraulic chamber 111) with respect to the position of the spool valve of the OCV 200. The hydraulic pressure is supplied to the advance side hydraulic chamber 111 by setting the position and driving the electric oil pump 20 to a complete stop. By driving the electric oil pump 20 as described above, the hydraulic pressure in the advance side hydraulic chamber 111 acts on the vane rotor 104 (that is, the intake camshaft 21) in addition to the biasing force of the torsion coil spring 110. The timing can be reliably set to the most advanced position, and the VVT 100 is reliably locked to the lock phase by the protrusion of the lock pin 113 at the most advanced position. Therefore, at the next start, the engine 1 can be started in a state where the opening / closing timing (closing timing) of the intake valve 13 is securely held (locked) at the most advanced position, and good startability is ensured. Can do.

  As described above, according to this example, the torsion coil spring 110 that advances the rotational phase of the intake camshaft 21 against the cam torque of the intake camshaft 21 and the electric oil pump that assists the hydraulic pressure supplied to the VVT 100. 20, the opening / closing timing of the intake valve 13 can be held at the most advanced angle phase by the biasing force of the torsion coil spring 110 when the engine 1 is started, and the electric oil pump is operated during idle operation. By driving 20, the opening / closing timing of the intake valve 13 can be delayed to eliminate valve overlap. As a result, it is possible to ensure good startability when the engine 1 is started and to ensure a stable idle operation state.

-Other embodiments-
In the above example, the VVT is provided on the intake camshaft. However, the present invention is not limited to this, and the present invention is also applicable to an engine provided with VVT on both the intake camshaft and the exhaust camshaft. Can do.

  In the above example, the control of the engine equipped with the vane type VVT has been described. Instead, the present invention is also applied to the control of the engine equipped with another type of VVT such as a helical spline type VVT. Can do.

  In the above example, an example in which the present invention is applied to a variable valve timing control device for a port injection type gasoline engine has been shown, but the present invention is not limited to this, and variable valve timing control for a direct injection gasoline engine in a cylinder. It is also applicable to the device. In addition to the in-line multi-cylinder gasoline engine, the variable valve timing control device of the present invention can be applied to a V-type multi-cylinder gasoline engine.

It is a schematic block diagram which shows an example of the engine to which the variable valve timing control apparatus of this invention is applied. FIG. 2 is a view illustrating a VVT mounted on the engine of FIG. 1 and a schematic configuration diagram of a hydraulic control system. It is XX sectional drawing of VVT of FIG. It is a block diagram which shows the structure of control systems, such as ECU. It is a figure which shows together the figure (A) which shows the opening / closing timing of the intake valve at the time of a stop and starting, and the figure (B) which shows the opening / closing timing of the intake valve at the time of idle operation.

Explanation of symbols

1 Engine 13 Intake valve 14 Exhaust valve 15 Crankshaft 18 Oil strainer 19 Mechanical oil pump 20 Electric oil pump (sub oil pump)
21 Intake camshaft 22 Exhaust camshaft 100 VVT (Variable valve timing mechanism)
101 vane housing 104 vane rotor 105 vane 107 front cover 107a spring guide 107b locking pin 109 timing pulley 110 torsion coil spring 111 advance side hydraulic chamber 112 retard side hydraulic chamber 113 lock pin 121 advance side passage 122 retard side passage 131 Oil supply passage 132 Oil discharge passage 133 Bypass passage 134 Check valve 140 Reserve tank 200 OCV (oil control valve)
300 ECU

Claims (3)

A hydraulically driven variable valve timing mechanism that adjusts the opening / closing timing of the intake valve by changing the rotation phase of the intake camshaft with respect to the crankshaft of the internal combustion engine, the mechanical oil pump driven by the rotation of the internal combustion engine, In a variable valve timing control device comprising a hydraulic control means for controlling the hydraulic pressure supplied from the mechanical oil pump to the variable valve timing mechanism,
An internal combustion engine comprising: an advance bias spring that advances the rotational phase of the intake camshaft against the cam torque of the intake camshaft; and a sub oil pump that is driven by power other than the rotation of the internal combustion engine. When the engine is started, the opening / closing timing of the intake valve is held at a predetermined advance position by the urging force of the advance urging spring. During idle operation after the internal combustion engine is started, the sub oil pump is driven. A variable valve timing control device for an internal combustion engine, wherein the opening / closing timing of the intake valve is retarded with respect to the advance angle position at the time of starting. The variable valve timing control device for an internal combustion engine according to claim 1,
A variable valve timing control device for an internal combustion engine, wherein the sub oil pump is driven during the stop operation of the internal combustion engine to advance the opening / closing timing of the intake valve to a predetermined advance position. The variable valve timing control device for an internal combustion engine according to claim 1 or 2,
The variable valve timing control device for an internal combustion engine, wherein the sub oil pump is an electric oil pump.

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