JP5030028B2 - Variable valve timing control device for internal combustion engine - Google Patents

Description

  The present invention relates to a variable valve timing control device for an internal combustion engine that adjusts valve timing by changing a rotational phase of a cam shaft (hereinafter referred to as “cam shaft phase”) with respect to a crankshaft of the internal combustion engine using hydraulic pressure as a drive source. .

  In recent years, in a hydraulically driven variable valve timing device, as described in Patent Document 1 (Japanese Patent Laid-Open No. 9-324613) and Patent Document 2 (Japanese Patent Laid-Open No. 2001-159330), the camshaft phase is changed. An intermediate lock mechanism that locks with an intermediate lock phase located approximately in the middle of the adjustable range is provided to expand the adjustable range of the cam shaft phase. In this system, when the engine is stopped, the hydraulic pressure supplied to the variable valve timing device is reduced while the camshaft phase is controlled to the advance side with respect to the intermediate lock phase, so that the camshaft phase is naturally generated by the cam torque. In this process, when the camshaft phase reaches the intermediate lock phase, the lock pin is pushed out by the spring and fitted into the lock hole, so that the camshaft phase is locked to the intermediate lock phase. It is locked in phase. This system sets the intermediate lock phase to a phase suitable for starting, starts with this intermediate lock phase, releases the lock after the start is completed, and controls the camshaft phase to the target phase set according to the engine operating state Like to do.

In addition, in order to correct the camshaft phase error due to manufacturing variations or aging of the variable valve timing device, the camshaft phase is forced as described in Japanese Patent Laid-Open No. 2001-82190. Then, it is changed to one limit phase (for example, the most retarded angle phase) of the adjustable range of the cam shaft phase, and the limit phase is learned as the reference phase of the cam shaft phase, and the actual cam is based on this reference phase. The shaft phase (for example, the actual advance angle amount from the reference phase) is calculated, and the target phase (for example, the target advance angle amount from the reference phase) is set according to the engine operating state with reference to the reference phase. Variable valve timing control (phase feedback control) for controlling the phase to the target phase is executed.
JP-A-9-324613 JP 2001-159330 A JP 2001-82190 A

  By the way, since the variable valve timing device with an intermediate lock mechanism starts with an intermediate lock phase, in order to learn the reference phase (the most retarded phase or the most advanced angle phase), the lock is released after the start is completed, and then the cam It is necessary to control the shaft phase to the reference phase, but if the lock is released immediately after the start is completed and the control is unconditionally controlled to the reference phase (the most retarded angle phase or the most advanced angle phase), the combustion stability will deteriorate and the engine will rotate. May become unstable or emissions may deteriorate. Therefore, after starting, it is necessary to wait until the engine operation state in which the camshaft phase can be controlled to the reference phase (the most retarded angle phase or the most advanced angle phase) without deteriorating the combustion stability and then learn the reference phase. Therefore, there are fewer opportunities for learning the reference phase, and it may take a long time to complete the learning of the reference phase.

  Since variable valve timing control cannot be performed until the reference phase learning is completed, if it takes a long time to complete the reference phase learning, the time during which the variable valve timing control cannot be performed also increases. The effect of fuel economy saving and output improvement by timing control cannot be obtained.

  In addition, it is conceivable that the intermediate lock phase is learned as a reference phase, and the control is performed based on the learning value of the intermediate lock phase. Since the error for clearance (play) for fitting the lock pin into the lock hole is included, the limit phase (the most retarded angle phase or the most advanced angle phase) of the adjustable range of the cam shaft phase is used as the reference phase. Compared to, the learning accuracy of the reference phase becomes worse.

  The present invention has been made in consideration of these circumstances. Therefore, the purpose of the variable valve timing device with an intermediate lock mechanism is not yet completed in learning of the reference phase (the most retarded phase or the most advanced angle phase). Even in this case, an object of the present invention is to provide a variable valve timing control device for an internal combustion engine that can quickly shift to variable valve timing control (phase feedback control) after starting.

  In order to achieve the above object, an invention according to claim 1 is a variable valve timing device that adjusts a valve timing by changing a rotational phase of a cam shaft (hereinafter referred to as “cam shaft phase”) with respect to a crankshaft of an internal combustion engine. An intermediate lock mechanism that locks the camshaft phase with an intermediate lock phase located approximately in the middle of the adjustable range; and a hydraulic control device that controls the hydraulic pressure that drives the variable valve timing device and the lock pin. In the variable valve timing control device for an internal combustion engine, intermediate lock phase learning that learns the cam shaft phase as the intermediate lock phase when the intermediate lock mechanism determines that the cam shaft phase is locked at the intermediate lock phase. And the camshaft phase has reached the most retarded phase or most advanced angle phase within the adjustable range. A reference phase learning unit that learns the cam shaft phase as a reference phase at a time, and a cam that controls the cam shaft phase to match the target phase by setting a target phase based on a learning value of the reference phase Shaft phase control means, and the cam shaft phase control means, when learning of the reference phase is incomplete and learning of the intermediate lock phase is completed, based on the learning value of the intermediate lock phase. Estimating the reference phase, narrowing the settable range of the target phase compared to when the learning of the reference phase is completed, and setting the target phase with reference to the estimated value of the reference phase to set the cam The axis phase is controlled.

  In a variable valve timing device with an intermediate lock mechanism, the internal combustion engine is started with the cam shaft phase locked at the intermediate lock phase by the intermediate lock mechanism, so learning of the intermediate lock phase can be performed immediately after the start. it can.

  In consideration of this point, in the present invention, when learning of the reference phase is not completed and learning of the intermediate lock phase is completed, the reference phase (the most retarded phase or Since the reference phase can be estimated immediately after starting, the learning value of the intermediate lock phase has a lock pin in addition to errors due to manufacturing variations and changes over time, as described above. Since an error corresponding to a clearance (play) for fitting in the lock hole is included, the estimated value of the reference phase may exceed the limit phase of the actual adjustable range of the cam shaft phase. For this reason, when the target phase is set based on the estimated value of the reference phase, the target phase is within the adjustable range of the actual cam shaft phase when the target phase is near the most retarded phase or the most advanced angle phase. The limit phase may be exceeded. If the target phase is set to a phase outside the adjustable range of the actual cam shaft phase and the cam shaft phase is controlled, the movable part (vane) of the variable valve timing device is the limit phase of the adjustable range of the cam shaft phase. May collide with the wall (stopper) vigorously and generate a loud collision sound, which may cause the driver to feel uncomfortable, or the components of the variable valve timing device may be damaged to deteriorate the durability.

  Therefore, in the present invention, when the target phase is set based on the estimated value of the reference phase estimated from the learned value of the intermediate lock phase, when the learning of the reference phase is completed (that is, the learned value of the reference phase is set). The target phase setting range is made narrower than when the target phase is set with reference. In this way, it is possible to keep the target phase set based on the estimated value of the reference phase within the adjustable range of the actual cam shaft phase, and the target phase is within the adjustable range of the actual cam shaft phase. It is possible to prevent the setting from exceeding the phase, and the movable part (vane) of the variable valve timing device vigorously collides with the limit phase wall (stopper) of the adjustable range of the camshaft phase, generating a loud collision sound. In addition, it is possible to prevent the durability of the variable valve timing device from being damaged due to damage. Thereby, even when learning of the reference phase (the most retarded angle phase or the most advanced angle phase) is not completed, it is possible to immediately shift to the variable valve timing control (phase feedback control) after starting.

  In this case, when the target phase is set based on the estimated value of the reference phase estimated from the learned value of the intermediate lock phase as in claim 2, the settable range of the target phase is the adjustable range of the cam shaft phase. It is preferable that the predetermined amounts A and B (see FIG. 4) are narrowed from both ends of each. Here, the predetermined amounts A and B allow for the estimation error of the reference phase so that the movable part (vane) of the variable valve timing device does not collide with the limit phase wall (stopper) of the adjustable range of the camshaft phase. The target phase may be set within the adjustable range of the actual camshaft phase.

  Further, as in claim 3, the early warm-up control (for example, increasing the internal EGR rate to increase the exhaust gas temperature) that controls the camshaft phase to the advance side or the retard side from the warm-up time at the time of cold start. When the present invention is applied to a system having an early warm-up control means for executing a control for promoting warm-up for a predetermined period, when the learning of the reference phase is not completed and the learning of the intermediate lock phase is completed The target phase for the early warm-up control is set based on the estimated value of the reference phase estimated based on the learning value of the intermediate lock phase, and the early warm-up control is executed. The reference phase may be learned by controlling the axial phase to the reference phase (the most retarded angle phase or the most advanced angle phase). In this way, even when learning of the reference phase (the most retarded angle phase or the most advanced angle phase) has not been completed, the early warm-up that quickly controls the camshaft phase to the advance side or the retard side after the start of cooling. The control can be executed and the reference phase can be quickly learned after the early warm-up control is completed.

  As in claim 4, the hydraulic control device includes a hydraulic control valve for phase control that controls the hydraulic pressure that drives the variable valve timing device, and a hydraulic control for lock control that controls the hydraulic pressure that drives the intermediate lock mechanism. A valve having a separate valve may be used, or, as in claim 5, a hydraulic control valve function for phase control for controlling the hydraulic pressure for driving the variable valve timing device and a hydraulic pressure for driving the intermediate lock mechanism It is also possible to use a hydraulic control valve that is integrated with a lock control hydraulic control valve function for controlling the control.

  Hereinafter, three embodiments 1 to 3 in which the best mode for carrying out the present invention is applied to a variable valve timing control device for an intake valve will be described.

A first embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, in an engine 11 that is an internal combustion engine, power from a crankshaft 12 is transmitted to an intake side camshaft 16 and an exhaust side camshaft 17 via sprockets 14 and 15 by a timing chain 13. It is like that. However, the intake side camshaft 16 is provided with a variable valve timing device 18 that adjusts the advance amount (camshaft phase) of the intake side camshaft 16 with respect to the crankshaft 12.

  A cam angle sensor 19 that outputs a cam angle signal pulse at a specific cam angle for cylinder discrimination is installed on the outer peripheral side of the intake side cam shaft 16, while a predetermined angle is provided on the outer peripheral side of the crank shaft 12. A crank angle sensor 20 that outputs a crank angle signal pulse for each crank angle is provided. The output signals of the cam angle sensor 19 and the crank angle sensor 20 are input to an engine control circuit 21, which calculates the actual valve timing (actual cam shaft phase) of the intake valve and the crank angle sensor. The engine speed is calculated based on the frequency of 20 output pulses (pulse interval). Further, output signals from various sensors (intake pressure sensor 22, water temperature sensor 23, throttle sensor 24, etc.) for detecting the engine operating state are input to the engine control circuit 21.

  The engine control circuit 21 performs fuel injection control and ignition control according to the engine operating state detected by the various sensors, performs variable valve timing control (phase feedback control), and performs actual valve timing (intake side) of the intake valve. The hydraulic pressure for driving the variable valve timing device 18 is feedback-controlled so that the actual cam shaft phase of the cam shaft 16 matches the target valve timing (target phase).

Next, the configuration of the variable valve timing device 18 will be described with reference to FIGS.
A housing 31 of the variable valve timing device 18 is fastened and fixed with bolts 32 to a sprocket 14 that is rotatably supported on the outer periphery of the intake camshaft 16. Thereby, the rotation of the crankshaft 12 is transmitted to the sprocket 14 and the housing 31 via the timing chain 13, and the sprocket 14 and the housing 31 rotate in synchronization with the crankshaft 12.
On the other hand, a rotor 35 is fastened and fixed to one end of the intake side camshaft 16 with a bolt 37. The rotor 35 is housed in the housing 31 so as to be relatively rotatable.

  As shown in FIG. 3, a plurality of oil filling chambers 40 are formed inside the housing 31, and each oil filling chamber 40 is advanced by an advance chamber 42 (advance angle) by a vane 41 formed on the outer peripheral portion of the rotor 35. Hydraulic chamber) and retarding chamber 43 (retarding hydraulic chamber). Stoppers 56 that restrict the relative rotation range of the rotor 35 (vane 41) with respect to the housing 31 are formed on both side portions of the at least one vane 41. The stopper 56 allows the camshaft phase to be adjusted in the latest range. The angular phase and the most advanced angle phase are regulated.

  The variable valve timing device 18 is provided with an intermediate lock mechanism 50 that locks the cam shaft phase with an intermediate lock phase located approximately in the middle of the adjustable range. The configuration of the intermediate lock mechanism 50 will be described. Any one or a plurality of vanes 41 is provided with a lock pin accommodation hole 57, and the lock pin accommodation hole 57 has a relative relationship between the housing 31 and the rotor 35 (vane 41). A lock pin 58 for locking the rotation is accommodated so as to protrude, and the lock pin 58 protrudes toward the sprocket 14 and fits into the lock hole 59 of the sprocket 14, so that the cam shaft phase is substantially within the adjustable range. Locked with an intermediate lock phase located in the middle. This intermediate lock phase is set to a phase suitable for starting the engine 11. The lock hole 59 may be provided in the housing 31.

  The lock pin 58 is urged in the lock direction (projection direction) by the spring 62. Further, between the outer peripheral portion of the lock pin 58 and the lock pin accommodation hole 57, an unlocking hydraulic chamber for controlling the hydraulic pressure for driving the lock pin 58 in the unlocking direction is formed. The housing 31 is provided with a torsion coil spring 55 (see FIG. 2) that assists the hydraulic pressure that relatively rotates the rotor 35 in the advance angle direction with the spring force during the advance angle control.

  In the first embodiment, the hydraulic control device that controls the hydraulic pressure that drives the variable valve timing device 18 and the lock pin 58 of the intermediate lock mechanism 50 is a hydraulic control for phase control that controls the hydraulic pressure that drives the variable valve timing device 18. The valve 25 and the lock control hydraulic control valve 26 for controlling the hydraulic pressure for driving the lock pin 58 of the intermediate lock mechanism 50 are individually provided. The hydraulic pressure control valve 25 for phase control is constituted by, for example, a 5-port, 3-position type spool valve, and the hydraulic pressure control valve 26 for lock control is constituted by, for example, a 3-port, 2-position type spool valve.

  The oil in the oil pan 27 is pumped up by an oil pump 28 driven by the power of the engine 11 and supplied to the hydraulic control valves 25 and 26, and the variable valve timing device 18 is advanced by the hydraulic control valve 25 for phase control. The hydraulic pressure (oil amount) supplied to the corner chamber 42 and the retard chamber 43 is controlled, and the hydraulic pressure (oil amount) for driving the lock pin 58 in the unlocking direction is controlled by the hydraulic control valve 26 for lock control. A check valve 29 for preventing backflow of oil is provided on the inlet port side of the hydraulic control valve 25 for phase control.

  The engine control circuit 21 calculates a target phase (target valve timing) based on engine operating conditions during phase feedback control (variable valve timing control), and calculates the actual cam shaft phase of the intake side camshaft 16 (the actual value of the intake valve). The control duty (control amount) of the hydraulic control valve 25 for phase control is feedback controlled so that the valve timing) matches the target phase (target valve timing), and the advance chamber 42 and the retard chamber of the variable valve timing device 18 are controlled. The hydraulic pressure supplied to 43 is feedback controlled.

  When a lock request is generated during this phase feedback control, lock control is executed to lock the actual camshaft phase with the intermediate lock phase by fitting the lock pin 58 into the lock hole 59 of the sprocket 14 as follows. . First, the lock control hydraulic control valve 26 is switched to the drain port, the hydraulic pressure in the lock release hydraulic chamber in the lock pin accommodation hole 57 is released, and the lock pin 58 is biased by the spring 62 in the lock direction (protrusion direction). However, variable phase control is performed to control the hydraulic control valve 25 for phase control so that the actual cam shaft phase passes the intermediate lock phase, and the actual cam shaft phase moves near the intermediate lock phase during this phase variable control. When the actual cam shaft phase still does not move when the control duty of the hydraulic control valve 25 for phase control is further changed by a predetermined amount in the direction in which the actual cam shaft phase is moved. Is inserted into the lock hole 59 and the actual cam shaft phase is locked at the intermediate lock phase), and the actual cam shaft phase at the time of the lock completion determination is determined as the intermediate lock phase. Stored in a rewritable non-volatile memory of the backup RAM or the like as a learning value (storage means). Note that the learning value of the intermediate lock phase may be stored in a volatile memory such as a RAM.

  Further, in the first embodiment, in order to perform the lock control of the lock pin 58 and the determination of the lock completion more reliably, when the actual camshaft phase stops moving near the intermediate lock phase during the phase variable control, The control duty of the hydraulic control valve 25 is changed alternately by a predetermined amount in the advance direction and the retard direction, and when the actual cam shaft phase does not move in either direction, it is determined that the lock is completed. .

  When the engine 11 is started, the engine 11 is cranked with a starter (not shown) while the actual camshaft phase is locked at the intermediate lock phase by the lock pin 58, and the phase is started from the lock mode after the start. Before shifting to the feedback control mode, the oil filling control for filling the advance chamber 42 and the retard chamber 43 of the variable valve timing device 18 with oil is executed, and the lock pin 58 is kept until the oil filling control is completed after the start. The lock pin 58 is kept in the locked state by prohibiting the unlocking of the lock.

  In the first embodiment, when a predetermined reference phase learning execution condition is satisfied during engine operation, the camshaft phase is forcibly set as one limit phase of the adjustable range of the camshaft phase, for example, the most retarded angle phase. (That is, retard until the vane 41 hits the stopper portion 56), for example, the most retarded angle phase is learned as the reference phase of the cam shaft phase, and the learning value of this reference phase is rewritten to the backup RAM or the like. Store in a possible non-volatile memory (storage means). The learning value of the reference phase may be stored in a volatile memory such as a RAM.

  When variable valve timing control (phase feedback control) is executed after completion of learning of the reference phase, an actual camshaft phase (for example, an actual advance angle amount from the reference phase) is calculated based on the learned value of the reference phase. The target phase (for example, the target advance angle amount from the reference phase) is set according to the engine operating state with reference to the learning value of the reference phase, and the actual camshaft phase is feedback-controlled to the target phase.

  By the way, when the reference phase learning value is stored in the backup RAM using the battery as a backup power source, the stored data of the reference phase learning value is retained even when the engine is stopped, but when the battery is removed from the vehicle. Since the stored data of the learning value of the reference phase disappears and the learning of the reference phase is incomplete, it is necessary to relearn the reference phase. In addition, when the learning value of the reference phase is stored in a volatile memory such as a RAM, the stored data of the learning value of the reference phase is deleted every time the engine is stopped. Need to learn.

  However, if the lock is released immediately after the start is completed and the control is unconditionally controlled to the reference phase (the most retarded angle phase or the most advanced angle phase), the combustion stability deteriorates and the engine rotation becomes unstable, or the emission deteriorates. there is a possibility. Therefore, after starting, it is necessary to wait until the engine operation state in which the camshaft phase can be controlled to the reference phase (the most retarded angle phase or the most advanced angle phase) without deteriorating the combustion stability and then to learn the reference phase. Therefore, there are fewer opportunities for learning the reference phase, and it may take a long time to complete the learning of the reference phase. Since variable valve timing control cannot be performed until the reference phase learning is completed, if it takes a long time to complete the reference phase learning, the time during which the variable valve timing control cannot be performed also increases. The effect of fuel economy saving and output improvement by timing control cannot be obtained.

  Thus, in the first embodiment, when the learning of the reference phase is not completed and the learning of the intermediate lock phase is completed, the reference phase is estimated based on the learning value of the intermediate lock phase, and the learning of the reference phase is performed. The settable range of the target phase is narrower than when the target phase is completed, and the camshaft phase is controlled by setting the target phase based on the estimated value of the reference phase.

  In this case, even if the stored data of the learned value of the intermediate lock phase disappears while the engine is stopped, when the engine 11 is started, the engine 11 is in a state where the actual camshaft phase is locked at the intermediate lock phase by the lock pin 58. Since the engine is started, learning of the intermediate lock phase can be performed promptly after the start.

  In consideration of this point, in the first embodiment, when the learning of the reference phase is not completed and the learning of the intermediate lock phase is completed, the reference phase (the most retarded angle) is based on the learning value of the intermediate lock phase. In order to estimate the phase or the most advanced angle phase), the reference phase can be estimated immediately after starting, but as described above, the learning value of the intermediate lock phase includes errors due to manufacturing variations and changes over time, Since an error for clearance (play) for fitting the lock pin 58 into the lock hole 59 is also included, the estimated value of the reference phase may exceed the limit phase of the actual adjustable range of the cam shaft phase. . For this reason, when the target phase is set based on the estimated value of the reference phase, the target phase is within the adjustable range of the actual cam shaft phase when the target phase is near the most retarded phase or the most advanced angle phase. The limit phase may be exceeded. If the target phase is set to a phase exceeding the adjustable range of the actual cam shaft phase and the cam shaft phase is controlled, the movable part (vane 41) of the variable valve timing device 18 is within the adjustable range of the cam shaft phase. It collides with the limit phase wall (stopper portion 56) vigorously and generates a loud collision sound, which causes the driver to feel uncomfortable, or damages the components of the variable valve timing device 18 to deteriorate the durability. there is a possibility.

  Therefore, in the first embodiment, when the target phase is set based on the estimated value of the reference phase estimated from the learned value of the intermediate lock phase, the learning of the reference phase is completed as shown in FIG. The target phase setting range is narrowed by a predetermined amount A and B from both ends of the cam shaft phase adjustment range, compared to the case (that is, when the target phase is set based on the learning value of the reference phase). . Here, the predetermined amounts A and B allow for an estimation error of the reference phase so that the vane 41 of the variable valve timing device 18 does not collide with the limit phase wall (stopper portion 56) of the adjustable range of the camshaft phase. Set it.

  In this way, it is possible to keep the target phase set based on the estimated value of the reference phase within the adjustable range of the actual cam shaft phase, and the target phase is within the adjustable range of the actual cam shaft phase. It is possible to prevent the phase from being exceeded, and the movable part (vane 41) of the variable valve timing device 18 collides with the wall (stopper portion 56) of the limit phase of the adjustable range of the cam shaft phase. The collision sound can be prevented from being generated, and the durability of the variable valve timing device 18 can be prevented from being damaged due to damage. Thereby, even when learning of the reference phase (the most retarded angle phase or the most advanced angle phase) is not completed, it is possible to immediately shift to the variable valve timing control (phase feedback control) after starting.

The variable valve timing control of the first embodiment described above is executed by the engine control circuit 21 according to the variable valve timing control routine of FIG.
The variable valve timing control routine of FIG. 5 is repeatedly executed at a predetermined cycle during the power-on period of the engine control circuit 21 (when the ignition switch is on), and serves as a cam shaft phase control means in the claims. Fulfill. When this routine is started, first, at step 101, whether or not learning of the reference phase (the most retarded phase or the most advanced angle phase) has been completed (the learning value of the reference phase is stored in a storage means such as a backup RAM). If it is determined that learning of the reference phase is incomplete, the process proceeds to step 102 to determine whether learning of the intermediate lock phase has been completed (such as in the backup RAM). It is determined whether or not storage data of the learning value of the intermediate lock phase exists in the storage means).

  As a result, if it is determined that learning of the intermediate lock phase is incomplete, the process proceeds to step 103 and lock control is executed. As a result, the hydraulic control valve 26 for lock control is switched to the drain port, the hydraulic pressure in the lock release hydraulic chamber in the lock pin accommodation hole 57 is released, and the lock pin 58 is attached in the locking direction (protruding direction) by the spring 62. The variable phase control for controlling the hydraulic control valve 25 for phase control is executed so that the actual camshaft phase passes the intermediate lock phase while the actual camshaft phase is in the vicinity of the intermediate lock phase. When it stops moving, the control duty of the hydraulic control valve 25 for phase control is further changed by a predetermined amount in the direction of moving the actual cam shaft phase. If the actual cam shaft phase still does not move, the lock is completed (lock pin 58 is fitted in the lock hole 59, and the actual camshaft phase is locked at the intermediate lock phase). Stored in storage means such as a backup RAM as the phase of the learning value. This process serves as intermediate lock phase learning means in the claims.

On the other hand, when the learning of the reference phase is not completed and the learning of the intermediate lock phase is completed (when “No” is determined in Step 101 and “Yes” is determined in Step 102), the process proceeds to Step 104. An estimated value of the reference phase is calculated based on the learning value of the lock phase. The estimated value of the reference phase is set to a phase separated from the learning value of the intermediate lock phase by a predetermined amount α toward the retard side.
Reference phase estimated value = intermediate lock phase learning value−α

  Here, as the predetermined amount α, a design value of the phase difference from the intermediate lock phase to the reference phase (the most retarded angle phase or the most advanced angle phase), the median value or the average value of the manufacturing variation range, or the like may be used. Data such as the design value of the predetermined amount α, the median value of the manufacturing variation range, or the average value may be stored in advance in a nonvolatile memory such as a ROM in the vehicle manufacturing process.

Thereafter, the routine proceeds to step 105, where the actual cam shaft phase (actual advance angle amount from the reference phase) is obtained by subtracting the reference phase estimation value from the absolute cam shaft phase (cam shaft phase detection value).
Actual camshaft phase = absolute camshaft phase−reference phase estimated value Thereafter, the routine proceeds to step 106, where the target phase (target advance amount from the reference phase) is determined according to the engine operating state with reference to the estimated value of the reference phase. calculate.

  Thereafter, the process proceeds to step 107, and the target phase is guarded so that the target phase falls within the target phase setting range when the reference phase is not learned as shown in FIG. Specifically, when the calculated value of the target phase calculated in step 106 exceeds the target phase setting range when the reference phase is not learned, the limit phase of the target phase setting range when the reference phase is not learned is finally set. When the target phase calculation value falls within the target phase setting range when the reference phase is not learned, the target phase calculation value is used as it is as the final target phase. Thereafter, the process proceeds to step 108, and phase feedback control is executed with reference to the reference phase estimated value using the final target phase after the guard processing.

Thereafter, when a predetermined reference phase learning execution condition is satisfied, the camshaft phase is forcibly changed to, for example, the most retarded phase that is one of the limit phases of the adjustable range of the camshaft phase (that is, the vane 41 is stopped by the stopper 41). For example, the most retarded angle phase is learned as a reference phase of the cam shaft phase, and the learned value of the reference phase is stored in a storage means such as a backup RAM. This process serves as reference phase learning means in the claims.
After completion of learning of the reference phase, “Yes” is determined in Step 101 described above, and the process proceeds to Step 109 to shift to phase feedback control using the reference phase learning value as a reference.

  In the first embodiment described above, when the learning of the reference phase is not completed and the learning of the intermediate lock phase is completed, the reference phase is estimated based on the learning value of the intermediate lock phase, and the learning of the reference phase is performed. Since the target phase setting range is narrower than when the target phase is completed, the target phase is set based on the estimated reference phase value and the camshaft phase is controlled. It is possible to keep the target phase set as a reference within the adjustable range of the actual cam shaft phase, preventing the target phase from being set beyond the adjustable range of the actual cam shaft phase. The movable part (vane 41) of the variable valve timing device 18 can be prevented from strikingly colliding with the limit phase wall (stopper portion 56) within the adjustable range of the camshaft phase and generating a large collision sound. Ba It is possible to prevent the durability component is damaged the blanking timing device 18 is deteriorated. As a result, even if the learning of the reference phase (the most retarded angle phase or the most advanced angle phase) has not been completed, it is possible to immediately shift to the variable valve timing control (phase feedback control) after the start of the variable valve timing control. The effect of saving fuel consumption and improving output can be obtained.

  Next, Embodiment 2 of the present invention will be described with reference to FIGS. However, description of parts substantially the same as those in the first embodiment will be omitted or simplified, and parts different from those in the first embodiment will be mainly described.

  In the second embodiment, the intake-side camshaft phase is controlled to the advance side (or the exhaust-side camshaft phase is retarded from the warm-up time) when warming up, for example, the internal EGR rate ( The early warm-up control is executed to increase the exhaust gas temperature by increasing the exhaust gas residual rate) and to promote the warm-up of the catalyst.

  Further, in the second embodiment, when the learning of the reference phase (the most retarded phase or the most advanced angle phase) is not completed and the learning of the intermediate lock phase is completed, the learning is performed based on the learned value of the intermediate lock phase. Based on the estimated value of the estimated reference phase, the target phase for the early warm-up control is set and the early warm-up control is executed. After the early warm-up control is finished, the camshaft phase is controlled to the reference phase and The reference phase is learned.

  A control example at the time of cold start of the variable valve timing device 18 of the second embodiment described above will be described with reference to FIG. In the example of FIG. 6, at the time t1, cranking is started while the actual camshaft phase is locked at the intermediate lock phase by the lock pin 58, and at the same time, the control duty of the hydraulic control valve 25 for phase control is advanced. Advance chamber oil filling control for filling the advance chamber 42 with oil is performed by setting, for example, the control duty (0%) of the most advanced angle phase, which is the advance duty on the advance side for filling the chamber 42 with oil. At the time t2 when the advance chamber oil filling control is executed for a predetermined time, the control duty of the hydraulic control valve 25 for phase control is the retard side duty for filling the retard chamber 43 with oil, for example, the most retarded phase. The control duty (100%) is switched to the retard chamber oil filling control for filling the retard chamber 43 with oil. From the start of cranking to the completion of the advance chamber oil filling control and the retard chamber oil filling control, unlocking of the lock pin 58 is prohibited and the lock pin 58 is maintained in the locked state.

  If it is determined at the time t3 when the retarded chamber oil filling control is executed for a predetermined time, if it is determined that the cooler is starting, the lock pin 58 is unlocked and the process proceeds to the early warm-up control. During the early warm-up control, the target phase is controlled to be advanced (or retarded) from the warm-up, and the internal EGR rate is increased to increase the exhaust temperature to promote the warm-up of the catalyst. .

  If the learning of the reference phase (the most retarded phase or the most advanced angle phase) is not completed and the learning of the intermediate lock phase is completed before the start of the early warm-up control, the learning value of the intermediate lock phase The target phase at the time of the early warm-up control is set based on the estimated value of the reference phase estimated based on the above, and the early warm-up control is executed.

  At the time t4 when this early warm-up control is executed for a predetermined time (or until the catalyst warm-up is completed), the target phase is set to the reference phase, for example, the most retarded angle phase, and the camshaft phase is forcibly camped. For example, the most retarded angle phase is changed to the most retarded phase which is one limit phase of the adjustable range of the axis phase (that is, retarded until the vane 41 hits the stopper portion 56), and the most retarded angle phase is set as a reference for the cam shaft phase. Learning is performed as the phase, and the learning value of the reference phase is stored in a storage unit such as a backup RAM.

  During this reference phase learning period, the camshaft phase is controlled to the reference phase (the most retarded angle phase or the most advanced angle phase), so that the combustion stability is reduced. Therefore, the target idle speed during the early warm-up control is reduced. Combustion stability is ensured by setting it higher than the normal target idle rotation speed and increasing the idle rotation speed during the early warm-up control to be higher than normal. At the time t5 when the learning of the reference phase is completed, the control shifts to normal control (lock control or phase feedback control).

  In the example of FIG. 6, the advance chamber oil filling control is performed after cranking is started, and then the retard chamber oil filling control is switched. However, the retard chamber oil filling control is performed on the contrary. May be switched to advance chamber oil filling control.

The variable valve timing control of the second embodiment described above is executed by the engine control circuit 21 according to the variable valve timing control routine of FIG.
The variable valve timing control routine of FIG. 7 is repeatedly executed at a predetermined cycle during the power-on period of the engine control circuit 21 (when the ignition switch is on), and serves as a cam shaft phase control means in the claims. Fulfill. When this routine is started, first, in step 201, it is determined whether or not learning of the reference phase (the most retarded phase or the most advanced angle phase) is completed, and the learning of the reference phase is incomplete. If it is determined, the routine proceeds to step 202, where it is determined whether learning of the intermediate lock phase is completed and the advance chamber / retard chamber oil filling control is completed.

  If it is determined as “No” in step 202 (that is, if it is determined that the learning of the intermediate lock phase is not completed and / or the advance chamber / retard chamber oil filling control is not completed), step Proceeding to step 203, the lock control is executed, the intermediate lock phase is learned, the learning value of the intermediate lock phase is stored in the storage means such as the backup RAM, and the advance chamber / retard chamber oil filling control is executed. .

On the other hand, when the learning of the reference phase is not completed and both the learning of the intermediate lock phase and the advance chamber / retard chamber oil filling control are completed (“No” in step 201 and “Yes” in step 202) If yes, the process proceeds to step 204, and the estimated value of the reference phase is calculated based on the learning value of the intermediate lock phase by the same method as in step 104 of FIG. 5 described in the first embodiment.
Reference phase estimated value = intermediate lock phase learning value−α

Thereafter, the process proceeds to step 205, where the actual cam shaft phase (actual advance angle amount from the reference phase) is obtained by subtracting the reference phase estimation value from the absolute cam shaft phase (cam shaft phase detection value).
Actual camshaft phase = absolute camshaft phase-reference phase estimate

Thereafter, the routine proceeds to step 206, where it is determined whether or not the early warm-up control execution condition is satisfied, for example, by whether or not the following conditions (1), (2) are satisfied.
(1) The engine coolant temperature must be below the specified temperature (when the cooler is started)
(2) Being in idle operation condition If these conditions (1), (2), etc. are all satisfied, the early warm-up control execution condition is satisfied, and if any one of the conditions is not satisfied, the early warm-up is performed. The control execution condition is not satisfied.

  If it is determined in step 206 that the conditions for executing the early warm-up control are satisfied, the process proceeds to step 207, where the target phase for the early warm-up control is determined based on the estimated value of the reference phase calculated in step 204. Is calculated. Thereafter, the process proceeds to step 208, where the lock pin 58 is unlocked, and the early warm-up control is executed.

  When the catalyst warm-up (engine coolant temperature is equal to or higher than the predetermined temperature) is completed by this early warm-up control, it is determined in step 206 that the early warm-up control execution condition is not satisfied, and the early warm-up control is terminated. In step 209, the camshaft phase is forcibly changed to, for example, the most retarded phase that is one of the limit phases of the adjustable range of the camshaft phase (that is, the retarded angle until the vane 41 hits the stopper portion 56). For example, the most retarded angle phase is learned as a reference phase of the cam shaft phase, and the learned value of the reference phase is stored in a storage means such as a backup RAM.

  After completion of the learning of the reference phase, “Yes” is determined in Step 201 described above, and the process proceeds to Step 209 to shift to normal control (phase feedback control or lock control based on the reference phase learning value).

  In the second embodiment described above, when the learning of the reference phase (the most retarded angle phase or the most advanced angle phase) is not completed and the learning of the intermediate lock phase is completed, the learning value of the intermediate lock phase is set. The target phase for the early warm-up control is set based on the estimated value of the reference phase estimated based on this, the early warm-up control is executed, and the camshaft phase is controlled to the reference phase after the early warm-up control is completed. Therefore, even if the learning of the reference phase (the most retarded phase or the most advanced angle phase) has not been completed, the camshaft phase is quickly advanced or retarded immediately after the cold start. It is possible to execute the early warm-up control to be controlled at the same time, and to quickly learn the reference phase after the end of the early warm-up control.

  In the first and second embodiments, the phase control hydraulic control valve 25 that controls the hydraulic pressure that drives the variable valve timing device 18 and the lock control hydraulic pressure that controls the hydraulic pressure that drives the lock pin 58 of the intermediate lock mechanism 50. Although the control valve 26 is provided separately, in the third embodiment of the present invention shown in FIGS. 8 and 9, the hydraulic control valve function for phase control for controlling the hydraulic pressure for driving the variable valve timing device 70 and the intermediate control valve are provided. A hydraulic control valve 71 that integrates a hydraulic control valve function for lock control that controls the hydraulic pressure that drives the lock pin 58 of the lock mechanism 50 is used.

  Since the configuration of the variable valve timing device 70 of the third embodiment is substantially the same as that of the variable valve timing device 18 described in the first embodiment, the same reference numerals as those in the first embodiment are used for description. Omitted.

  On the other hand, a hydraulic control valve 71 in which a hydraulic control valve function for phase control and a hydraulic control valve function for lock control are integrated is constituted by, for example, an 8-port, 4-position type spool valve. As shown in FIG. 9, according to the control duty of the hydraulic control valve 71, it is divided into four control areas: a lock mode (weak advance angle mode), an advance angle mode, a holding mode, and a retard angle mode.

  In the control region of the lock mode (weak advance angle mode), the lock pin control port of the hydraulic control valve 71 is communicated with the drain port, and the hydraulic pressure in the lock release hydraulic chamber in the lock pin accommodation hole 57 is released. While urging the lock pin 58 in the locking direction (protruding direction) and communicating the retard port to the drain port and releasing the hydraulic pressure of the retard chamber 43, the hydraulic pressure is controlled according to the control duty of the hydraulic control valve 71. By gradually changing the throttle of the oil passage at the advance port of the control valve 71, oil is gradually supplied from the advance port to the advance chamber 42 to drive the actual camshaft phase gradually in the advance direction.

  In the control region of the advance angle mode, the retard control port 71 of the hydraulic control valve 71 is connected to the drain port, and the hydraulic pressure of the retard chamber 43 is released, and the hydraulic control valve 71 is controlled according to the control duty of the hydraulic control valve 71. The actual camshaft phase is advanced by changing the hydraulic pressure supplied to the advance chamber 42 from the advance port.

In the control region of the holding mode, the hydraulic pressures of both the advance chamber 42 and the retard chamber 43 are held so that the actual cam shaft phase does not move.
In the control region of the retard angle mode, the hydraulic control valve 71 is communicated according to the control duty of the hydraulic control valve 71 with the advance port of the hydraulic control valve 71 connected to the drain port and the hydraulic pressure of the advance chamber 42 is released. The actual camshaft phase is retarded by changing the hydraulic pressure supplied to the retard chamber 43 from the retard port.

  In control areas other than the lock mode (retarding mode, holding mode, advance angle mode), the unlocking hydraulic chamber in the lock pin receiving hole 57 is filled with oil to increase the hydraulic pressure of the unlocking hydraulic chamber, The lock pin 58 is extracted from the lock hole 59 by hydraulic pressure, and the lock pin 58 is unlocked.

  In the third embodiment, the control mode is switched in the order of the lock mode (weak advance mode), the advance mode, the holding mode, and the retard mode as the control duty of the hydraulic control valve 71 increases. However, for example, as the control duty of the hydraulic control valve 71 increases, the control mode is switched in the order of the retard angle mode, the holding mode, the advance angle mode, and the lock mode (weak advance angle mode), or Alternatively, the order of the retard angle mode and the advance angle mode may be switched so that the control mode is switched in the order of the lock mode (weak advance angle mode), the retard angle mode, the holding mode, and the advance angle mode. In addition, when the control area in the lock mode (weak advance angle mode) and the control area in the retard angle mode are continuous, in the control area in the lock mode (weak advance angle mode), the lock is released in the lock pin accommodation hole 57. The hydraulic pressure in the hydraulic chamber is released and the lock pin 58 is urged in the locking direction (protruding direction) by the spring 62, and the hydraulic pressure in the advanced chamber 42 is released by connecting the advance port to the drain port. In accordance with the control duty of the control valve 71, the oil passage throttle of the retarding port is changed little by little, and oil is gradually supplied from the retarding port to the retarding chamber 43 to gradually retard the actual camshaft phase. Drive in the direction.

  Also in the third embodiment, similarly to the first embodiment, when the learning of the reference phase is not completed and the learning of the intermediate lock phase is completed, the reference phase is estimated based on the learned value of the intermediate lock phase. Then, the target phase setting range is narrower than when the reference phase learning is completed, and the camshaft phase may be controlled by setting the target phase based on the estimated reference phase value. .

  Alternatively, as in the second embodiment, when the learning of the reference phase (the most retarded angle phase or the most advanced angle phase) is not completed and the learning of the intermediate lock phase is completed, the learning value of the intermediate lock phase The target phase for early warm-up control is set based on the estimated value of the reference phase estimated based on, and the early warm-up control is executed. After the early warm-up control is completed, the camshaft phase is controlled to the reference phase. Then, the reference phase may be learned.

The present invention is not limited to an intake valve variable valve timing control device, and may be applied to an exhaust valve variable valve timing control device.
In addition, the present invention can be implemented with various modifications within a range not departing from the gist, such as the configuration of the variable valve timing devices 18 and 70 and the configuration of the hydraulic control valves 25, 26, and 71 may be appropriately changed. .

It is a schematic block diagram of the whole control system which shows Example 1 of this invention. It is a vertical side view explaining the structure of the variable valve timing apparatus of Example 1, and a hydraulic control circuit. It is a vertical front view of the variable valve timing device of the first embodiment. FIG. 6 is a diagram for explaining a relationship among a target phase settable range after completion of reference phase unlearned according to the first embodiment, a target phase settable range when reference phase is not learned, and a camshaft phase adjustable range. 3 is a flowchart showing a flow of processing of a variable valve timing control routine according to the first embodiment. It is a time chart explaining the example of control at the time of the cold start of the variable valve timing apparatus of Example 2. FIG. 7 is a flowchart showing a flow of processing of a variable valve timing control routine according to a second embodiment. It is a vertical side view explaining the structure of the variable valve timing apparatus of Example 3, and a hydraulic control circuit. (A) is a figure explaining the switching pattern of the advance port, retard port, and lock pin control port of the hydraulic control valve of Example 3, (b) is the lock mode, advance mode, holding mode, and retard mode It is a control characteristic figure of a hydraulic control valve explaining the relation between these four control fields and phase change speed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Crankshaft, 13 ... Timing chain, 14, 15 ... Sprocket, 16 ... Intake camshaft, 17 ... Exhaust camshaft, 18 ... Variable valve timing device, 19 ... Cam angle sensor, 20 ... Crank angle sensor, 21 ... Engine control circuit (camshaft phase control means, intermediate lock phase learning means, reference phase learning means, oil filling control means), 25 ... hydraulic control valve (hydraulic control device) for phase control, 26 ... hydraulic control valve (hydraulic control device) for lock control, 28 ... oil pump, 31 ... housing, 35 ... rotor, 40 ... fluid chamber, 41 ... vane, 42 ... advance chamber, 43 ... retard chamber, 50 ... Intermediate lock mechanism, 58 ... Lock pin, 59 ... Lock hole, 62 ... Spring, 70 ... Variable valve timing device, 71 ... Hydraulic control valve (hydraulic control device)

Claims (5)

A variable valve timing device that adjusts the valve timing by changing the rotational phase of the camshaft relative to the crankshaft of the internal combustion engine (hereinafter referred to as “camshaft phase”), and the camshaft phase is positioned approximately in the middle of the adjustable range. In a variable valve timing control device for an internal combustion engine, comprising: an intermediate lock mechanism that locks at an intermediate lock phase; and a hydraulic control device that controls the hydraulic pressure that drives the variable valve timing device and the lock pin;
Intermediate lock phase learning means for learning the cam shaft phase as the intermediate lock phase when the intermediate lock mechanism determines that the cam shaft phase is locked at the intermediate lock phase;
Reference phase learning means for learning the cam shaft phase as a reference phase when it is determined that the cam shaft phase has reached the most retarded angle phase or the most advanced angle phase of the adjustable range;
Cam shaft phase control means for setting a target phase with reference to the learning value of the reference phase and controlling the cam shaft phase to match the target phase;
When the learning of the reference phase is not completed and the learning of the intermediate lock phase is completed, the cam shaft phase control means estimates the reference phase based on the learning value of the intermediate lock phase, and The camshaft phase is controlled by setting the target phase on the basis of the estimated value of the reference phase, narrowing the settable range of the target phase as compared with the case where learning of the reference phase is completed. A variable valve timing control device for an internal combustion engine.   When setting the target phase based on the estimated value of the reference phase, the cam shaft phase control means sets the target phase settable range by a predetermined amount from each end of the cam shaft phase adjustable range. 2. The variable valve timing control device for an internal combustion engine according to claim 1, wherein the variable valve timing control device is narrowed. Early warm-up control means for performing a predetermined period of early warm-up control for controlling the camshaft phase to the advance side or retard side from the warm-up time at the time of cold start,
If the learning of the reference phase is not completed and the learning of the intermediate lock phase is completed, the early warm-up control means estimates the reference phase estimated based on the learned value of the intermediate lock phase The target phase of the early warm-up control is set with reference to, and the early warm-up control is executed.
3. The variable internal combustion engine according to claim 1, wherein the reference phase learning unit controls the camshaft phase to the reference phase after the early warm-up control and learns the reference phase. 4. Valve timing control device.   The hydraulic control device individually includes a hydraulic control valve for phase control that controls the hydraulic pressure that drives the variable valve timing device, and a hydraulic control valve for lock control that controls the hydraulic pressure that drives the intermediate lock mechanism. The variable valve timing control device for an internal combustion engine according to any one of claims 1 to 3, wherein the variable valve timing control device is configured.   The hydraulic control device integrates a hydraulic control valve function for phase control that controls the hydraulic pressure that drives the variable valve timing device and a hydraulic control valve function for lock control that controls the hydraulic pressure that drives the intermediate lock mechanism. The variable valve timing control device for an internal combustion engine according to any one of claims 1 to 3, wherein the hydraulic control valve is used.

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