JP6332186B2 - Engine cam phase control device - Google Patents

Description

  The present invention relates to an engine cam phase control device.

  The rotational phase of the camshaft relative to the crankshaft may deviate from the normal state (target rotational phase) depending on the tension of the timing chain that is wound around the crank sprocket and the cam sprocket of the engine.

  Conventionally, a technique for coping with this phase shift problem is known (see, for example, Patent Document 1). In Patent Document 1, the amount of camshaft phase shift is determined based on the detection values of a crank angle sensor that detects the rotation angle (crank angle) of the crankshaft and a cam angle sensor that detects the rotation angle of the camshaft. It is calculated every time the crank angle advances by 180 °, and when the calculated phase deviation exceeds a predetermined value, the camshaft phase is adjusted so that the camshaft phase approaches the normal state by the variable valve timing mechanism (VVT). It is described that the phase is corrected (see FIG. 8 of Patent Document 1).

JP 2002-309994 A

  By the way, the tension of the timing chain changes every moment, and the manner of the change varies depending on the operating state of the engine such as the engine speed and the engine load (torque). However, in the technique described in Patent Document 1, the calculation of the phase shift amount is performed every time the crank angle advances by 180 °, and each time the calculation is performed, only the phase is corrected. The phase shift is intermittent, and the phase shift while the crank angle advances by 180 ° is not eliminated. For this reason, the technique described in Patent Document 1 cannot accurately suppress the phase shift.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an engine cam timing control device capable of accurately suppressing the rotational phase of a cam shaft from deviating from a normal state. To do.

In order to solve the above problems, the present invention is an engine cam phase control device for controlling a rotational phase of a camshaft to which a driving force of a crankshaft constituting an engine is transmitted via an endless transmission member, A tensioner device that presses the endless transmission member, an operating state detecting means that detects the operating state of the engine, a variable valve timing mechanism that changes the rotational phase of the camshaft, and the variable that is set for each operating state of the engine. The cam that is a value for correcting the target control value of the valve timing mechanism and is expected to occur with respect to the target rotation phase of the cam shaft when the variable valve timing mechanism is controlled by the target control value. A storage unit storing a predicted amount of phase shift of the shaft or a correction value set so as to suppress the predicted phase shift, and the operation state detecting means The predicted phase shift amount or correction value corresponding to the engine operating state is read from the storage unit, the correction control value of the variable valve timing mechanism is calculated based on the read expected phase shift amount or correction value, and the correction A control unit that controls the variable valve timing mechanism so as to suppress an anticipated rotational phase shift based on a control value, and the tensioner device uses the hydraulic pressure generated by the supply of hydraulic oil to move the endless transmission member. Provided is an engine cam phase control device , wherein the engine operating state is an engine speed, an engine load, and a temperature of hydraulic oil supplied to the tensioner device. .

According to the present invention, when the variable valve timing mechanism is controlled by the target control value, the expected cam shaft phase shift amount or the expected phase shift is expected to occur with respect to the target rotation phase of the cam shaft. The correction value set so as to be set is set for each engine operating state. Then, the correction control value of the variable valve timing mechanism is calculated based on the predicted phase shift amount or the correction value, and the cam shaft phase control is performed based on the correction control value. It is suppressed in advance. Therefore, according to the present invention, the rotational phase shift of the camshaft can be accurately suppressed regardless of the operating state of the engine.
In particular, since the variable valve timing mechanism is controlled so that the occurrence of a camshaft phase shift is suppressed even if the engine speed, the engine load, and the temperature of the hydraulic fluid of the tensioner device change, the camshaft Can be accurately suppressed.

  In the present invention, it is preferable that the expected phase shift amount or the correction value is set corresponding to a continuous change in the crank angle.

  According to this configuration, the occurrence of a camshaft phase shift is suppressed in advance at all crank angles.

  In the present invention, it further comprises phase shift detection means for detecting a phase shift amount of the cam shaft with respect to the target rotational phase, and the control unit is configured to perform the control based on the phase shift amount detected by the phase shift detection means. It is preferable to control the variable valve timing mechanism so that the phase shift amount of the cam shaft is small.

  According to this configuration, even if the cam shaft phase shift occurs due to the extension of the endless transmission member, the phase shift amount can be reduced.

  As described above, according to the present invention, the occurrence of a rotational phase shift of the cam shaft from the normal state (target rotational phase) can be accurately suppressed.

It is a figure which shows the structure of the cam phase control apparatus of the engine which concerns on embodiment of this invention. It is a figure which shows the driving | running state of the engine in embodiment of this invention three-dimensionally with an engine speed, an engine load, and hydraulic fluid temperature. It is a figure which shows the example of the estimated rotational deviation amount and control value in embodiment of this invention, (a) is the estimated rotational deviation amount when an engine speed is a1, an engine load is b1, and hydraulic oil temperature is c1. (Solid line) and a diagram showing a correction value (dashed line), (b) is an expected rotation deviation amount (solid line) and correction value when the engine speed is a2, the engine load is b2, and the hydraulic oil temperature is c2. It is a figure which shows a dashed-dotted line. It is a flowchart which shows operation | movement of the control part in embodiment of this invention. It is a figure which shows the effect by embodiment of this invention, (a) is a graph which shows the relationship between the crank angle when not controlling step S6 in FIG. 4, and a valve lift, (b) is FIG. It is a graph which shows the relationship between the crank angle at the time of performing control of step S6 in, and valve lift amount. It is a figure which shows the effect by the conventional cam phase control apparatus, (a) is a graph which shows the relationship between the crank angle before performing cam phase control, and valve lift amount, (b) is the conventional cam phase control apparatus. 6 is a graph showing a relationship between a crank angle and a valve lift amount when the control according to FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  The engine cam phase control device 1 according to this embodiment includes an exhaust camshaft 20 and an intake camshaft to which the driving force of the crankshaft 18 is transmitted via a timing chain (corresponding to the “endless transmission member” of the present invention) 14. 21 is a device for controlling the rotational phase of the motor 21.

  The cam phase control device 1 includes a throttle sensor 5, an oil temperature sensor 6, a crank angle sensor 7, a cam angle sensor 8, an ECU (Engine Control Unit) 4, an exhaust side variable valve timing mechanism (hereinafter referred to as "exhaust gas"). Side VVT (Variable Valve Timing system) ”2, an intake side variable valve timing mechanism (hereinafter referred to as“ intake side VVT ”) 3, and a tensioner device 13.

  The accelerator opening sensor 5, the oil temperature sensor 6, the crank angle sensor 7, the intake cam angle sensor 12, the exhaust cam angle sensor 11, and the ECU 4 correspond to the “driving state detection means” of the present invention. The accelerator opening sensor 5, the oil temperature sensor 6, the crank angle sensor 7, the intake cam angle sensor 12, and the exhaust cam angle sensor 11 are connected to an input terminal of the ECU 4.

  The accelerator opening sensor 5 detects the amount of depression of the accelerator pedal by the driver as the accelerator opening. Based on the detected accelerator opening, the amount of air supplied to the combustion chamber of the engine is calculated. Therefore, a throttle opening sensor that detects the throttle opening may be used instead of the accelerator opening sensor 5. The oil temperature sensor 6 detects the temperature of the hydraulic oil supplied to the tensioner device 11. The crank angle sensor 7 detects the rotation angle of the crankshaft 18. The intake cam angle sensor 12 detects the rotation angle of the intake cam shaft 21, and the exhaust cam angle sensor 11 detects the rotation angle of the exhaust cam shaft 20.

  The exhaust side VVT2 is an electric VVT provided on the exhaust camshaft 20, and the exhaust valve is opened and closed by continuously changing the rotational phase of the exhaust camshaft 20 with respect to the crankshaft 18 within a predetermined angular range. Change the timing. The exhaust camshaft 20 and the exhaust side sprocket 15 are connected via the exhaust side VVT2.

  The intake side VVT3 is an electric VVT provided on the intake camshaft 21. By continuously changing the rotational phase of the intake camshaft 21 with respect to the crankshaft 18 within a predetermined angle range, the intake valve is opened and closed. Change the timing. The intake camshaft 21 and the intake side sprocket 16 are connected via the intake side VVT3.

  A crank sprocket 17 is provided on the crankshaft 17. A timing chain 14 is wound around the crank sprocket 17, the exhaust side sprocket 15, and the intake side sprocket 16. The crank sprocket 17 rotates clockwise (clockwise) in FIG. 1, and the timing chain 14 is rotated clockwise with the rotation.

  The ECU 4 is a microcomputer provided with a CPU and a memory 4a composed of ROM, RAM, etc., and the CPU (corresponding to the “control unit” of the present invention) refers to programs and data stored in the memory 4a. A predetermined function is realized by executing various processes.

  The memory 4a stores a correction value (a dashed line L1 in FIGS. 3A and 3B) for correcting a target control value of the exhaust side VVT2 (a target advance amount or a target retard amount of the exhaust cam shaft 20 with respect to the crankshaft 18). Reference value) and a correction value for correcting the target control value of the intake side VVT3 (the target advance amount or the target retard amount of the intake camshaft 21 with respect to the crankshaft 18) (one-dot chain line L1 in FIGS. 3A and 3B) Reference) is stored in advance. The target control value for the exhaust side VVT2 and the target control value for the intake side VVT3 are calculated based on the engine speed and the engine load (torque).

  The correction value for the exhaust-side VVT 2 is a value obtained through experiments or the like, and is set for each operating state of the engine 9. The correction value of the exhaust side VVT2 is set to the target rotation phase of the exhaust camshaft 20 (the target advance amount or the target retard amount of the exhaust camshaft 20 with respect to the crankshaft 18) when the exhaust side VVT2 is controlled by the target control value. On the other hand, it is set to suppress the rotational phase shift of the exhaust camshaft 20 that is expected to occur. This phase shift occurs when the tension of the timing chain 14 changes momentarily according to the engine operating state such as the engine speed and engine load (torque). In the present embodiment, the correction value of the exhaust side VVT2 is an expected phase shift amount of the exhaust camshaft 20 that is expected to occur with respect to the target rotation phase of the exhaust camshaft 20 (solid line in FIGS. 3A and 3B). L2) is the same size and opposite in value. That is, when the correction value of the exhaust side VVT2 is added to the expected phase shift amount of the exhaust camshaft 20, the expected position shift amount is canceled.

  More specifically, the “operation state of the engine 9” in the present embodiment refers to the engine speed, the engine load (torque), and the temperature of hydraulic oil supplied to the tensioner device 13 (hereinafter referred to as “hydraulic oil temperature”). It is. The correction value is a value set in advance using four values of the engine speed [rpm], engine load [N · m], hydraulic oil temperature [° C.], and crank angle [deg] as parameters.

  Specifically, for example, three values (see FIG. 2) of the engine speed a1 [rpm], the engine load b1 [N · m], and the hydraulic oil temperature c1 [° C.] include the crank angle [deg] and One correction pattern (see FIG. 3A) showing the relationship with the correction value [deg] corresponds. As shown in FIG. 3A, the correction value is set corresponding to a continuous change in the crank angle. In the example shown in FIG. 3A, the correction value changes sinusoidally with respect to the continuous change in the crank angle.

  The three values (see FIG. 2) of the engine speed a2 [rpm], the engine load b2 [N · m], and the hydraulic oil temperature c2 [° C.] include the crank angle [deg] and the correction value [deg]. Corresponds to one correction pattern (see FIG. 3B).

  The correction value of the intake side VVT 3 is a value obtained by experiments or the like, and is set for each operating state of the engine 9. The correction value of the intake side VVT3 is set to the target rotation phase of the intake camshaft 21 (the target advance angle amount or the target delay angle amount of the intake camshaft 21 with respect to the crankshaft 18) when the intake side VVT3 is controlled by the target control value. On the other hand, it is set to suppress an expected phase shift of the intake camshaft 21 that is expected to occur. In the present embodiment, the correction value of the intake side VVT 3 is the same in magnitude as the expected phase shift amount of the intake camshaft 21 that is expected to occur with respect to the target rotation phase of the intake camshaft 21, but is opposite in value. is there. That is, if the correction value of the intake side VVT3 is added to the expected phase shift amount of the intake camshaft 21, the expected position shift amount is canceled out.

  The tensioner device 13 presses the timing chain 14 in a section between the crank sprocket 17 and the exhaust side sprocket 15. The tensioner device 13 includes a tensioner arm 10 that is swingably attached to the side surface of the engine 9 in contact with the timing chain 14, and a tensioner body 19 that is an actuator that presses the tension arm 10. The tensioner body 19 is a hydraulic actuator, and the temperature of the hydraulic oil supplied to the actuator is detected by a temperature sensor (not shown) set in the engine hydraulic circuit. This temperature sensor is connected to the ECU 4 via a communication line.

  Next, processing performed by the ECU 4 will be described with reference to FIG.

  First, the ECU 4 detects the rotational phase shift amount of the exhaust camshaft 20 with respect to the target rotational phase of the exhaust camshaft 20 based on the detection value of the exhaust cam angle sensor 11 and based on the detection value of the intake cam angle sensor 12. Thus, the rotational phase shift amount of the intake camshaft 21 with respect to the target rotational phase of the intake camshaft 21 is detected (step S1).

  For example, the rotational phase shift amount can be detected by preliminarily storing the positional relationship between the most retarded angle positions of the exhaust side VVT2 and the intake side VVT3 and the phase of a predetermined camshaft as a reference position in the ECU 4 so that the actual VVT is the maximum. This is done by calculating the positional relationship between the retard position and the camshaft phase and calculating the amount of deviation from the reference position.

  Next, the ECU 4 controls the exhaust side VVT 2 so that the rotational phase shift of the exhaust camshaft 20 becomes small based on the rotational phase shift amount of the exhaust camshaft 20 detected in step S1. Similarly, the ECU 4 controls the intake side VVT 3 so that the rotational phase shift of the intake camshaft 21 becomes small based on the rotational phase shift amount of the intake camshaft 21 detected in step S1 (step S2).

  In the control of step S2, the timing chain 14 is worn and extended due to long-term use of the engine or the like, so that the exhaust camshaft 20 deviates from the target rotational phase of the exhaust camshaft 20, or the intake camshaft In this case, when the rotational phase shift occurs in the intake camshaft 21 with respect to the 21 target rotational phase, the rotational phase shift is controlled afterwards.

  Next, the ECU 4 detects the driving state of the vehicle, that is, three values of the engine speed, the engine load, and the hydraulic oil temperature (step S3). Specifically, the ECU 4 detects the engine speed based on the detection value of the crank angle sensor 7, and calculates the engine load based on the detection value of the crank angle sensor 7 and the detection value of the accelerator opening sensor 5. .

  Next, the ECU 4 calculates a target control value for the exhaust side VVT2 and a target control value for the intake side VVT3 based on the engine speed and the engine load (step S4).

  Next, the ECU 4 reads from the memory 4a a correction pattern of the exhaust side VVT2 (see the one-dot chain line L1 in FIGS. 3A and 3B) corresponding to the detected engine speed, engine load, and hydraulic oil temperature (see FIG. In step S5), a correction control value for the exhaust side VVT2 is calculated by correcting the target control value for the exhaust side VVT2 based on the read correction pattern, and it is predicted that this will occur due to a change in the operating state based on the correction control value. The exhaust side VVT2 is controlled so as to suppress the rotational phase shift (step S6).

  Similarly, the ECU 4 reads out from the memory 4a the correction pattern of the intake side VVT2 (see the one-dot chain line L1 in FIGS. 3A and 3B) corresponding to the detected engine speed, engine load, and hydraulic oil temperature. (Step S5) When the correction control value of the intake side VVT3 is calculated by correcting the target control value of the intake side VVT3 based on the read correction pattern, and the change occurs in the operating state based on the correction control value The intake side VVT3 is controlled so as to suppress the expected rotational phase shift (step S6).

  FIG. 5 is a diagram showing the effect of this embodiment. According to the present embodiment, by performing the control in step S6 in FIG. 4, the rotational phase deviation of the exhaust camshaft 20 and the intake camshaft 21 is substantially zero over the entire range of the crank angle 0 to 720 [deg]. As a result, as shown in FIG. 5B, the valve target lift amount (see the broken line A1) and the actual lift amount (see the solid line A3) over the entire range of the crank angle 0 to 720 [deg]. ) Is almost zero. FIG. 5A is a diagram showing the relationship between the target lift amount of the valve (see the broken line A1) and the actual lift amount (see the solid line A2) when the control of step S6 in FIG. 4 is not performed. . When the control of step S6 is not performed, it can be seen that there is a large deviation between the target lift amount (see the broken line A1) and the actual lift amount (see the solid line A2).

  On the other hand, when the phase correction described in Patent Document 1 is performed, the phase shift correction is performed for an average period of crankshaft rotation, so the rotational phase shift of the camshaft is completely eliminated. As a result, as shown in FIG. 6 (b), the target lift amount of the valve (see the broken line A1) and the actual value over the most part of the crank angle 0 to 720 [deg]. The deviation from the lift amount (see the solid line A4) is not eliminated. FIG. 6A is a graph showing the relationship between the crank angle and the valve lift before the cam phase control described in Patent Document 1.

  As described above, according to the present embodiment, the rotational phase shift of the exhaust camshaft 20 that is expected to occur with respect to the target rotational phase of the exhaust camshaft 20 when the exhaust side VVT2 is controlled with the target control value. Therefore, a correction value for correcting the target control value of the exhaust side VVT2 is set for each operating state of the engine 9. Then, the correction control value of the exhaust side VVT 2 is calculated based on the correction value, and the phase control of the exhaust cam shaft 20 is performed based on the correction control value. It is suppressed. The same applies to the intake camshaft 21. Therefore, according to the present embodiment, the rotational phase shift between the exhaust camshaft 20 and the intake camshaft 21 can be accurately suppressed regardless of the operating state of the engine 9.

  Further, according to the present embodiment, since the correction value is set corresponding to the continuous change of the crank angle, the exhaust camshaft 20 and the intake camshaft 21 may be out of phase at all crank angles. It is suppressed in advance.

  Further, according to the present embodiment, the occurrence of a phase shift between the exhaust camshaft 20 and the intake camshaft 21 is suppressed even when the engine speed, the engine load, and the temperature of the hydraulic fluid of the tensioner device 13 change. The exhaust side VVT2 and the intake side VVT3 are controlled. Therefore, the rotational phase shift of the exhaust camshaft 20 and the intake camshaft 21 can be suppressed with high accuracy.

  Further, according to the present embodiment, even if the exhaust camshaft 20 and the intake camshaft 21 are shifted in phase due to the extension of the timing chain 14, the amount of phase shift can be reduced.

  In the above-described embodiment, the correction value (see the one-dot chain line L1 in FIG. 3) is stored in the memory 4a. Instead, the expected phase shift amount (see the solid line L2 in FIG. 3) is stored in the memory 4a. The phase control may be performed by calculating a correction value based on the expected phase shift amount.

1 Cam Phase Control Device 4 ECU (Control Unit)
4a Memory (storage unit)
9 Engine 11 Tensioner device
14 Timing chain (endless transmission member)
18 Crankshaft 20 Exhaust camshaft 21 Intake camshaft

Claims (3)

A cam phase control device for an engine that controls a rotational phase of a camshaft in which a driving force of a crankshaft constituting an engine is transmitted through an endless transmission member,
A tensioner device for pressing the endless transmission member;
An operating state detecting means for detecting the operating state of the engine;
A variable valve timing mechanism for changing the rotational phase of the camshaft;
A value that is set for each operating state of the engine to correct the target control value of the variable valve timing mechanism, and when the variable valve timing mechanism is controlled by the target control value, the target rotation of the camshaft A storage unit that stores an expected phase shift amount of the camshaft that is expected to occur with respect to a phase or a correction value that is set to suppress the expected phase shift;
An expected phase shift amount or correction value corresponding to the engine operating state detected by the operating state detection means is read from the storage unit, and the variable valve timing mechanism correction control is performed based on the read expected phase shift amount or correction value. A control unit that calculates a value and controls the variable valve timing mechanism so as to suppress an expected rotational phase shift based on the correction control value ;
The tensioner device presses the endless transmission member with hydraulic pressure generated by supplying hydraulic oil,
The engine cam phase control device is characterized in that the operating state of the engine is an engine speed, an engine load, and a temperature of hydraulic oil supplied to the tensioner device.   2. The engine cam phase control device according to claim 1, wherein the rotational phase shift amount or the correction value is set corresponding to a continuous change in a crank angle. A phase shift detecting means for detecting a phase shift amount of the cam shaft with respect to the target rotation phase;
The control unit controls the variable valve timing mechanism so that a phase shift amount of the cam shaft is reduced based on a phase shift amount detected by the phase shift detection unit. The cam phase control device for an engine according to 1 or 2 .

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