JP6421672B2 - Variable valve system - Google Patents

Description

  The present invention relates to a variable valve system that changes the opening / closing timing of a valve in an internal combustion engine.

  The internal combustion engine includes an intake valve and an exhaust valve. Each valve is opened and closed at an appropriate timing in synchronization with the rotation of the crankshaft of the internal combustion engine. Specifically, when the crankshaft rotates, the camshaft rotates in conjunction with this, and a plurality of cams provided on the camshaft open and close the respective valves.

  Even if the valve opening / closing timing, that is, the crank angle when the valve is opened / closed, is always constant, the internal combustion engine can be operated. However, it is known that the optimal opening / closing timing of the valve is not always the same, and varies depending on the operating condition (rotation speed, torque, etc.) of the internal combustion engine.

  For this reason, a system capable of changing the opening / closing timing of the valve according to the operating state, that is, a variable valve system has been developed and has already been put into practical use. The variable valve system changes the relationship between the rotation angle (crank angle) of the crankshaft and the rotation angle (cam angle) of the camshaft, that is, the camshaft phase, which is the relative rotation angle of the camshaft with respect to the crankshaft. Accordingly, the opening / closing timing of at least one of the intake valve and the exhaust valve is changed (for example, see Patent Document 1 below).

  In the variable valve system, it is necessary to make the cam shaft phase coincide with the target value when performing control for making the valve opening / closing timing appropriate. For this reason, a sensor for measuring the crank angle and a sensor for measuring the cam angle are provided, respectively, and the cam shaft phase at the present time is calculated based on the measured values of these sensors.

Japanese Patent No. 4123127

  In the variable valve system described in Patent Document 1, a sensor for measuring the crank angle is provided as a sensor for measuring the crank angle by counting the number of pulses generated along with the rotation of the crankshaft. It is used. Further, as a sensor for measuring the cam angle, there is used a sensor of a type that counts the number of pulses generated as the cam shaft rotates and thereby measures the cam angle.

  This type of sensor does not directly measure the absolute rotation angle of the cam shaft or the like (absolute value of the cam angle or the like), but measures the amount of change in the cam angle or the like from a specific state. . Therefore, as long as the number of pulses is continuously counted, an absolute value such as a cam angle can be measured.

  However, for example, when the crankshaft rotates in a state where the ignition switch of the vehicle is turned off (a state where no pulse is counted) due to, for example, so-called “pushing”, the ignition switch is subsequently turned on. When is turned on, the absolute value of the cam angle at that time cannot be measured immediately. As a result, when starting the internal combustion engine, the camshaft phase cannot be accurately calculated, and the internal combustion engine may start in a state where the camshaft phase does not match the target value. In that case, abnormal combustion such as pre-ignition occurs because the intake valve and the exhaust valve are opened and closed at inappropriate timing.

  The present invention has been made in view of such problems, and an object thereof is to provide a variable valve system capable of opening and closing a valve at an appropriate timing even immediately after the internal combustion engine is started. .

In order to solve the above-mentioned problems, a variable valve system according to the present invention is a variable valve system that changes the opening / closing timing of a valve in an internal combustion engine, and includes a crank angle measurement unit that measures a rotation angle of a crankshaft of the internal combustion engine; A cam angle measuring unit that measures a rotation angle of a cam shaft that opens and closes a valve in conjunction with the crankshaft, and a control unit that performs control at the start of the internal combustion engine. The cam angle measurement unit is configured as an absolute angle sensor that measures the absolute rotation angle of the cam shaft, and the control unit controls the start time based on the rotation angle of the cam shaft measured by the cam angle measurement unit. To start. The control unit stores a first angle that is the rotation angle of the camshaft when the internal combustion engine was previously stopped, and the second angle that is the rotation angle of the camshaft immediately before the start-time control is started is the first angle. If the angle coincides with the angle, the start-time control is started without waiting for confirmation of the rotation angle of the crankshaft.

  In the variable valve system having such a configuration, the cam angle measuring unit that measures the rotation angle of the cam shaft is configured as an absolute angle sensor that measures the absolute rotation angle of the cam shaft. For this reason, the crank angle can be grasped instantaneously and accurately before the start control is started, regardless of whether or not the crankshaft is rotated while the vehicle is stopped. As a result, the camshaft phase can be matched with the target value within a relatively short time, and the valve can be opened and closed at an appropriate timing.

  According to the present invention, there is provided a variable valve system capable of opening and closing a valve at an appropriate timing even immediately after the internal combustion engine is started.

It is a figure which shows typically the structure of the variable valve system which concerns on 1st Embodiment of this invention. It is a time chart which shows the change of the state of the vehicle carrying the variable valve system of FIG. It is a time chart which shows the change of the state of the vehicle carrying the variable valve system of FIG. It is a flowchart which shows the flow of the process performed by the control part of the variable valve system of FIG. It is a time chart which shows the change of the state of the vehicle carrying the variable valve system which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the flow of the process performed by the control part of the variable valve system which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same constituent elements in the drawings will be denoted by the same reference numerals as much as possible, and redundant description will be omitted.

  The variable valve system 10 according to the first embodiment is mounted on a vehicle including an internal combustion engine (not shown), and is for changing the opening / closing timing of an intake valve in the internal combustion engine. The above configuration is merely an example, and the variable valve system 10 may change the opening / closing timing of the exhaust valve. Further, the opening / closing timings of the intake valve and the exhaust valve may be individually changed.

  The configuration of the vehicle will be described with reference to FIG. In FIG. 1, only the part necessary for explaining the configuration and operation of the variable valve system 10 described later is shown in the vehicle. The vehicle includes a crankshaft 200 that rotates by a driving force of an internal combustion engine, and a camshaft 300 that rotates in conjunction with the crankshaft 200.

  The crankshaft 200 is provided with a pulley 210 and a detection object 230. The pulley 210 is a substantially disk-shaped rotating body, and the crankshaft 200 penetrates the center of the main surface thereof vertically. The pulley 210 is fixed to the crankshaft 200, and when the crankshaft 200 rotates, the pulley 210 also rotates accordingly.

  A timing chain 250 is hung on the outer peripheral surface of the pulley 210. The rotation of the pulley 210, that is, the rotation of the crankshaft 200 is transmitted to the variable valve system 10 (an outer gear 320 described later) via the timing chain 250 and is transmitted to the camshaft 300 via the variable valve system 10.

  The detected object 230 is a substantially disk-shaped rotating body, and the crankshaft 200 penetrates the center of the main surface vertically. The detected body 230 is fixed to the crankshaft 200, and when the crankshaft 200 rotates, the detected body 230 also rotates.

  The detected object 230 is for the crank angle sensor 240 that is a part of the variable valve system 10 to detect the rotation angle of the crankshaft 200 (hereinafter also referred to as “crank angle”). A plurality of protrusions are formed at equal intervals on the outer periphery of the detection object 230. However, the intervals between the protrusions are not all the same, but only one place is different from the others.

  The crank angle sensor 240 is provided so as to face the outer peripheral surface of the detection object 230. When the crankshaft 200 and the detected object 230 rotate, the detected object 230 generates a voltage pulse every time the protrusion of the detected object 230 passes through the vicinity. The pulse, that is, a signal indicating a measured value of the crank angle is input to the control unit 100. The control unit 100 measures the crank angle by counting the pulses.

  When a portion (hereinafter, also referred to as “missing tooth portion”) where the interval between the protrusions formed on the detection object 230 is different from the other passes through the crank angle sensor 240, that is, the interval between pulses that has been constant changes. When this is detected, the control unit 100 recognizes that the crank angle has reached a specific value (for example, 0 °). As described above, the missing tooth portion formed on the outer periphery of the detection object 230 functions as a part for the control unit 100 to recognize (determine) the absolute value of the crank angle.

  The cam shaft 300 is a shaft to which a cam (not shown) for opening and closing the intake valve is attached. The camshaft 300 rotates in conjunction with the rotation of the crankshaft 200, and the intake valve is opened and closed by the cam movement associated therewith.

  The camshaft 300 is provided with an inner gear 310 that is a part of the variable valve system 10 and a detection object 330. The inner gear 310 is a substantially disk-shaped rotating body, and the cam shaft 300 penetrates the center of the main surface thereof vertically. The inner gear 310 is fixed with respect to the cam shaft 300, and when the inner gear 310 rotates, the cam shaft 300 also rotates accordingly. As will be described in detail later, the variable valve system 10 transmits the rotation of the crankshaft 200 to the camshaft 300 via the inner gear 310, thereby rotating the camshaft 300.

  The detected object 330 is a substantially disk-like (but not a perfect circle) rotating body, and the cam shaft 300 penetrates the center of the main surface vertically. The detected body 330 is fixed to the camshaft 300, and when the camshaft 300 rotates, the detected body 330 also rotates.

  The detected object 330 is for the cam angle sensor 340 that is a part of the variable valve system 10 to detect the rotation angle of the cam shaft 300 (hereinafter also referred to as “cam angle”).

  The cam angle sensor 340 is provided so as to face the outer peripheral surface of the detection object 330. The main surface of the detection object 330 is not a perfect circle. For this reason, when the camshaft 300 and the detected object 330 rotate, the gap between the cam angle sensor 340 and the outer peripheral surface of the detected object 330 gradually changes with the rotation.

  The shape of the detection object 330 is set so that the relationship between the rotation angle value (0 ° to 360 °) of the camshaft 300 and the size of the gap is 1: 1. The cam angle sensor 340 is configured as a so-called gap sensor, and outputs a voltage signal corresponding to the size of the gap. That is, the cam angle sensor 340 is a sensor (absolute angle sensor) that can measure the absolute value of the cam angle. The voltage signal, that is, a signal indicating the measured value (absolute value) of the cam angle is input to the control unit 100.

  As described above, when the crankshaft 200 of the internal combustion engine rotates, the rotation is transmitted to the camshaft 300 via the timing chain 250 and the variable valve system 10, thereby rotating the camshaft 300. In a vehicle having such a configuration, the intake valve opening / closing timing, that is, the crank angle when the intake valve is opened / closed, is a relative rotation angle of the cam shaft 300 with respect to the crank shaft 200 (hereinafter referred to as “cam shaft phase”). ”). The variable valve system 10 changes the opening / closing timing of the intake valve by changing the camshaft phase.

  As schematically shown in FIG. 1, the variable valve system 10 includes an inner gear 310, an outer gear 320, a planetary gear 420, a motor 400, a support shaft 410, and a control unit 100. .

  As described above, the inner gear 310 is fixed to the cam shaft 300 and rotates integrally with the cam shaft 300. On the outer peripheral surface of the inner gear 310, external teeth (not shown) that mesh with a planetary gear 420 described later are formed.

  The outer gear 320 is a ring-shaped member that forms part of a sprocket (not shown) that rotates in synchronization with the crankshaft 200. The outer gear 320 is arranged in a state where the central axis thereof coincides with the central axis of the cam shaft 300. A timing chain 250 is hung on the outer peripheral surface of the outer gear 320 (sprocket). For this reason, when the crankshaft 200 and the pulley 210 rotate, the rotation is transmitted to the outer gear 320 via the timing chain 250, and thereby the outer gear 320 rotates. Inner teeth (not shown) that mesh with the planetary gear 420 are formed on the inner peripheral surface of the outer gear 320.

  The planetary gear 420 is a circular gear that is arranged in mesh with both the outer teeth of the inner gear 310 and the inner teeth of the outer gear 320. The planetary gear 420 can be swung in a circular orbit along the outer peripheral surface of the inner gear 310 by a motor 400 and a support shaft 410 described later.

  The motor 400 is a rotating electric machine that operates by receiving power. The motor 400 is for turning the planetary gear 420 along the outer peripheral surface of the inner gear 310. The rotation speed of the motor 400 is controlled by the control unit 100. The motor 400 outputs a pulsed voltage signal to the control unit 100 every time the rotation angle of the rotation shaft (output shaft) changes by a predetermined amount (for example, 10 °). Such a voltage signal is generated by a hall sensor (not shown) built in the motor 400.

  The support shaft 410 is connected to the motor 400 and the planetary gear 420. The support shaft 410 includes a rotating part 411, a connecting part 412, and a support part 413.

  The rotating portion 411 is a portion that is integral with the rotating shaft of the motor 400, and is arranged in a state in which the central axis thereof coincides with the central axis of the cam shaft 300. The connecting part 412 is a part formed so as to extend perpendicularly to the central axis of the rotating part 411 from the end part of the rotating part 411 (the end opposite to the motor 400). The support part 413 is a part formed so as to extend in parallel with the central axis of the rotating part 411 from the end part of the connecting part 412 (the end part opposite to the rotating part 411). The end portion of the support portion 413 (the end portion opposite to the connecting portion 412) is connected to the planetary gear 420. The planetary gear 420 is attached to the end portion of the support portion 413 so as to be rotatable around the central axis of the support portion 413.

  As already described, the rotation speed of the motor 400 is controlled by the control unit 100. When the rotation speed of the motor 400, that is, the turning speed of the planetary gear 420 is the same as the rotation speed of the outer gear 320 (sprocket), the rotation speed of the inner gear 310 and the camshaft 300 is the same as the rotation speed of the outer gear 320. The same. In such a state, the value of the cam shaft phase is constant, so that the opening / closing timing of the intake valve is also always constant.

  On the other hand, when the rotational speed of the motor 400 changes and the turning speed of the planetary gear 420 is different from the rotational speed of the outer gear 320, the camshaft phase changes. As a result, the opening / closing timing of the intake valve changes.

  Thereafter, when the rotational speed of the motor 400 becomes the same as the rotational speed of the outer gear 320 again, the camshaft phase again becomes a constant value (however, a value different from that before the rotational speed of the motor 400 changes), and the intake air The opening / closing timing of the valve becomes constant again. Thus, the rotational speed of the motor 400 is temporarily different from the rotational speed of the outer gear 320 to change the camshaft phase, thereby changing the opening / closing timing of the intake valve. .

  The control unit 100 controls the overall operation of the variable valve system 10 and the operation of the internal combustion engine. The control unit 100 is configured as a computer system including a CPU, a RAM, a ROM, an interface, and the like.

  The control unit 100 controls the rotation speed of the motor 400, thereby matching the camshaft phase with the target value. Specifically, the crank angle is calculated based on the pulse input from the crank angle sensor 240, and the cam angle is calculated based on the voltage signal input from the cam angle sensor 340. Thereafter, the current cam shaft phase is calculated based on the difference between the crank angle and the cam angle. While the calculated camshaft phase is fed back, the rotation speed of the motor 400 is controlled so that the camshaft phase matches the target value.

  The operation of the variable valve system 10 will be described with reference to FIG. In FIG. 2, changes in the state of the vehicle equipped with the variable valve system 10 are shown by five time charts. Of these five time charts, (A) shows the time change of the state (ON or OFF) of the ignition switch provided in the vehicle. (B) shows the time change of the rotational speed of the internal combustion engine. (C) shows the time change of the operating state (ON or OFF) of the control unit 100. (D) shows a change in the value of the camshaft phase calculated by the control unit 100. (E) shows a change in the crank angle measured by the crank angle sensor 240 and calculated by the control unit 100.

  In FIGS. 3 and 5 described later, five time charts are shown as in FIG. In each figure, what is indicated by (A), (B), (C), (D), (E) is the same as that shown in each time chart of FIG. 2 (the state of the ignition switch, etc.). It is.

  FIG. 2 shows a change in the state of the vehicle when the ignition switch is turned ON again at time t30 after the ignition switch is turned OFF from time ON at time t10.

  In a period prior to time t10, the ignition switch is in an ON state (FIG. 2A), and the control unit 100 is also in operation (ON) (FIG. 2C). . The rotational speed of the internal combustion engine (also referred to as the rotational speed of the crankshaft 200) is a substantially constant value SP10 (FIG. 2B). Further, the cam angle phase is controlled to be a target value (value CF10) (FIG. 2D).

  The crank angle is repeatedly increased from the lower limit value CL10 (for example, 0 °) to the upper limit value CL20 (for example, 360 °) (FIG. 2E). Note that the timing at which the crank angle returns from the upper limit value CL20 to the lower limit value CL10 is the timing at which the missing tooth portion of the detected object 230 passes the crank angle sensor 240.

  When the ignition switch is turned off by the driver at time t10, the rotational speed of the internal combustion engine gradually decreases from the value SP10 and finally becomes 0 (FIG. 2 (B)). After time t10, at least until the number of revolutions of the internal combustion engine becomes zero, the control unit 100 remains in operation (FIG. 2 (C)). Meanwhile, measurement of the crank angle by the crank angle sensor 240 and measurement of the cam angle by the cam angle sensor 340 are continuously performed (FIG. 2E). Further, the calculation and control of the cam angle phase based on these are continuously performed (FIG. 2D).

  When the rotational speed of the internal combustion engine becomes 0, the control unit 100 stops its operation and is turned off (time t20). Since the control unit 100 is stopped, the crank angle measurement by the crank angle sensor 240, the cam angle measurement by the cam angle sensor 340, and the time from the time t20 to the time t30 when the ignition switch is turned ON, Neither calculation nor control of the cam angle phase based on these is performed.

  In the example shown in FIG. 2, during the period from time t20 to time t30, the vehicle remains stopped and the crank angle does not change. That is, the crank angle, cam angle, and cam angle phase at time t30 are the same as the crank angle, cam angle, and cam angle phase at time t20, respectively.

  The control unit 100 stores the crank angle and the cam angle when the operating state was previously turned off (time t20). The crank angle and the cam angle stored at time t20 are also referred to as “previous crank angle” and “previous cam angle”, respectively.

  When the ignition switch is turned on at time t30, control unit 100 starts control for starting the internal combustion engine (hereinafter also referred to as “starting time control”). The start-up control includes ignition control for adjusting ignition (ignition timing and ignition energy) in the internal combustion engine, and injection control for adjusting fuel injection. Also included is cam shaft phase control for matching the cam shaft phase to the target value.

  In order to perform the start-up control, the control unit 100 needs to grasp the current crank angle and cam angle. Therefore, in the case of the example shown in FIG. 2, that is, when the crank angle does not change while the vehicle is stopped, the control unit 100 uses the stored previous crank angle as the current crank angle. Use.

  The control unit 100 can quickly grasp the current crank angle without waiting for the missing tooth portion of the detected object 230 to pass through the crank angle sensor 240 and thereby determine the value of the crank angle. As a result, the starting control can be started quickly.

  At time t30, the crank angle, cam angle, and cam shaft phase are immediately calculated. For this reason, the internal combustion engine is started immediately, and its rotational speed increases (FIG. 2 (B)). Similarly to the period before time t10, after time t30, the crank angle repeatedly increases from the lower limit value CL10 to the upper limit value CL20 (FIG. 2E).

  FIG. 3 shows an example in which the crank angle changes during a period from time t20 to time t30 (period in which the vehicle is stopped). Such a change in the crank angle occurs, for example, when a so-called “push” is performed in the vehicle. In the example of FIG. 3, the crank angle at time t20 (ie, the previous crank angle) is the value CL15. Further, the crank angle at time t30 is a value CL16. As the crank angle changes, the cam angle also changes.

  As already described, the cam angle sensor 340 is a sensor (absolute angle sensor) that can measure the absolute value of the cam angle. Therefore, even when the crank angle and the cam angle change while the vehicle is stopped as described above, the cam angle can be measured immediately at time t30. On the other hand, since the crank angle of the crank angle sensor 240 changes while the vehicle is stopped (however, the amount of change is unknown), the previous crank angle cannot be used as the current crank angle.

  Therefore, in the example shown in FIG. 3, the crankshaft 200 is rotated by performing so-called cranking after time t30. When the detected object 230 rotates and the missing tooth portion of the detected object 230 passes near the crank angle sensor 240, the crank angle can be determined at that time. In FIG. 3, the time when the crank angle is determined as described above is shown as time t40. Further, the value of the rotational speed of the internal combustion engine when cranking is being performed is indicated as a value SP05 (FIG. 3B). The value SP05 is a value smaller than the value SP10.

  After time t40, the crank angle and the cam angle are both calculated, and the calculation and control of the cam angle phase is started based on these. In the example shown in FIG. 3D, the cam angle phase (measured value of the cam angle phase at time t40) calculated immediately after the crank angle is determined is a value CF05 that is different from that before stopping. Thereafter, the cam angle phase control is started, so that the cam angle phase immediately changes from the value CF05 to the target value (value CF10).

  After time t40 when the cam angle phase control is started, the control unit 100 starts ignition control and injection control following the cam angle phase control.

  In the period from time t30 when cranking is performed to time t40, the crankshaft 200 is rotating and the actual value of the crank angle is changing. However, the crank angle as the measurement value is not fixed as described above, and the control unit 100 cannot grasp the accurate value. For this reason, FIG. 3E does not show the change in the crank angle (measured value) in the period from time t30 to time t40.

  The specific contents of the processing performed by the control unit 100 in order to realize the operation as shown in FIGS. 2 and 3 will be described with reference to FIG. FIG. 4 is a flowchart showing a flow of processing executed when the vehicle is started.

  In the first step S01, it is determined whether or not the ignition switch is ON. If the ignition switch is OFF, the series of processes shown in FIG. 4 is terminated. If the ignition switch is ON, the process proceeds to step S02.

  In step S02, the cam angle is read. That is, the current cam angle is calculated based on the voltage signal input from the cam angle sensor 340.

  In step S03 following step S02, it is determined whether or not the current cam angle read in step S02 (hereinafter also referred to as “current cam angle”) is the same as the stored previous cam angle. The If the current cam angle is the same as the previous cam angle, the process proceeds to step S04.

  The transition to step S04 means that the crank angle did not change while the vehicle was stopped, as in the example shown in FIG. That is, the current crank angle is the same as the stored previous crank angle.

  For this reason, in step S04, the stored previous crank angle is set as the current crank angle. The control unit 100 quickly grasps the current crank angle without waiting for the missing tooth portion of the detection object 230 to pass through the crank angle sensor 240 and thereby determining the value of the crank angle.

  In step S05 following step S04, start-up control (ignition control, injection control, camshaft phase control) is started. The start-up control in this case has already been described as control performed after time t30 in FIG.

  In step S03, when the current cam angle is different from the previous cam angle, the process proceeds to step S06. The transition to step S06 means that the crank angle has changed as a result of being pushed while the vehicle is stopped, as in the example shown in FIG. That is, the current crank angle is different from the previously stored crank angle.

  Therefore, in step S06, cranking is started to determine the crank angle. In step S07 following step S06, it is determined whether or not the crank angle has been determined. When the crank angle is determined, the process proceeds to step S08. When the crank angle has not been determined, that is, when the missing tooth portion of the detected object 230 has not yet passed through the crank angle sensor 240, the process of step S07 is repeatedly executed.

  After the time of transition to step S08 (time t40 in FIG. 3), both the crank angle and the cam angle are calculated. For this reason, in step S08, the calculation and control of the cam angle phase is started. Thereafter, the process proceeds to step S05, and start-up control (ignition control, injection control, camshaft phase control) is started. The start-up control in this case has already been described as control performed after time t40 in FIG.

  As described above, in the variable valve system 10 according to the first embodiment, the startup control is started based on the measured value of the cam angle sensor 340 that is an absolute angle sensor. When the control unit 100 starts operating, the current cam angle is measured immediately and accurately. For this reason, the intake valve can be opened and closed at an appropriate timing even immediately after the internal combustion engine is started.

  If the stored previous cam angle is lost for some reason (for example, noise), the previous cam angle cannot be read in step S03. In such a case, the process is forcibly shifted from step S03 to step S06, and the processes after step S06 are performed.

  In addition, it is assumed that the previous crank angle and the previous cam angle are not stored when the control unit 100 is stopped, and the process after step S06 is always performed after step S01. It is good.

  A variable valve system (not shown) according to a second embodiment of the present invention will be described. In the second embodiment, the crank angle sensor 240 of the variable valve system 10 shown in FIG. 1 is replaced with an absolute angle sensor similar to the cam angle sensor 340. Specifically, the detected object 230 of the crankshaft 200 is replaced with one having the same configuration as the detected object 330, and the crank angle sensor 240 is replaced with a gap sensor similar to the cam angle sensor 340. The control unit 100 according to the second embodiment calculates the absolute value of the crank angle based on the value of the voltage signal input from the crank angle sensor 240.

  FIG. 5 shows changes in the state of a vehicle equipped with the variable valve system 10 according to the second embodiment. Also in the present embodiment, during the period from time t20 to time t30 when the control unit 100 is OFF, measurement of the crank angle by the crank angle sensor 240, measurement of the cam angle by the cam angle sensor 340, and based on these. Neither calculation nor control of the cam angle phase is performed.

  When the ignition switch is turned on at time t30, the control unit 100 starts the starting control. Also in the present embodiment, in order to perform the start-up control, the control unit 100 needs to grasp the current crank angle and cam angle.

  In the present embodiment, not only the cam angle sensor 340 but also the crank angle sensor 240 is configured as an absolute angle sensor. Therefore, regardless of whether or not the crank angle has changed during the period from time t20 to time t30, an accurate crank angle sensor is measured immediately at time t30 (without waiting for missing teeth to pass by cranking). Is possible.

  Since both the crank angle and the cam angle are calculated after time t30, the calculation and control of the cam angle phase is started based on these. In the example shown in FIG. 5D, the cam angle phase calculated first after time t30 (actual value of the cam angle phase at time t30) is a value CF05 different from that before stopping. Thereafter, the cam angle phase control is started, so that the cam angle phase immediately changes from the value CF05 to the target value (value CF10). The state of the vehicle after the cam angle phase control is started at time t30 is the same as the state of the vehicle after time t30 in FIG. 2 and after time t40 in FIG.

  In order to realize the operation shown in FIG. 5, the specific contents of the processing performed by the control unit 100 will be described with reference to FIG. FIG. 6 is a flowchart showing a flow of processing executed when the vehicle is started.

  In the first step S11, it is determined whether or not the state of the ignition switch is ON. If the ignition switch is OFF, the series of processes shown in FIG. If the ignition switch is on, the process proceeds to step S12.

  In step S12, the crank angle is read out. That is, the current crank angle is calculated based on the voltage signal input from the crank angle sensor 240.

  In step S13 following step S12, the cam angle is read. That is, the current cam angle is calculated based on the voltage signal input from the cam angle sensor 340.

  In step S14 following step S13, start-up control (ignition control, injection control, camshaft phase control) is started. The start-up control in this case has already been described as control performed after time t30 in FIG.

As described above, in the variable valve system 10 according to the second embodiment, the measured value of the crank angle sensor 240, which is an absolute angle sensor, and the measured value of the cam angle sensor 340, which is an absolute angle sensor,
Based on both of these, the starting control is started. When the control unit 100 starts to operate, both the current crank angle and the cam angle are measured immediately and accurately. For this reason, the intake valve can be opened and closed at an appropriate timing even immediately after the internal combustion engine is started.

  In the above, the configuration in which the cam angle phase is changed by the driving force of the motor 400 has been described, but the embodiment of the present invention is not limited to such a configuration. For example, the cam angle phase may be changed not by a rotating electrical machine such as the motor 400 but by an operation of a hydraulic mechanism.

  Further, the absolute angle sensor is not limited to the method of detecting the gap, and may be a method of detecting the rotation angle by other means.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. In other words, those specific examples that have been appropriately modified by those skilled in the art are also included in the scope of the present invention as long as they have the characteristics of the present invention. For example, the elements included in each of the specific examples described above and their arrangement, materials, conditions, shapes, sizes, and the like are not limited to those illustrated, but can be changed as appropriate. Moreover, each element with which each embodiment mentioned above is provided can be combined as long as technically possible, and the combination of these is also included in the scope of the present invention as long as it includes the features of the present invention.

10: Variable valve system 100: Control unit 200: Crank shaft 240: Crank angle sensor 300: Cam shaft 340: Cam angle sensor 400: Motor 410: Support shaft

Claims (7)

A variable valve system that changes the opening and closing timing of a valve in an internal combustion engine,
A crank angle measuring unit (240) for measuring a rotation angle of the crankshaft (200) of the internal combustion engine;
A cam angle measuring unit (340) for measuring a rotation angle of a cam shaft (300) that opens and closes the valve in conjunction with the crank shaft;
A control unit (100) for performing start-up control of the internal combustion engine,
The cam angle measurement unit is configured as an absolute angle sensor that measures an absolute rotation angle of the cam shaft,
The controller is
Based on the rotation angle of the cam shaft measured by the cam angle measuring unit, the control at the start is started ,
The controller is
Storing a first angle which is a rotation angle of the camshaft when the internal combustion engine was previously stopped;
When the second angle, which is the rotation angle of the camshaft immediately before the start time control is started, coincides with the first angle, the start time control is performed without waiting for the determination of the rotation angle of the crankshaft. A variable valve system characterized by starting . 2. The variable valve system according to claim 1 , wherein when the second angle is different from the first angle, the start-time control is started after the rotation angle of the crankshaft is determined. A variable valve system that changes the opening and closing timing of a valve in an internal combustion engine,
A crank angle measuring unit (240) for measuring a rotation angle of the crankshaft (200) of the internal combustion engine;
A cam angle measuring unit (340) for measuring a rotation angle of a cam shaft (300) that opens and closes the valve in conjunction with the crank shaft;
A control unit (100) for performing start-up control of the internal combustion engine,
The cam angle measurement unit is configured as an absolute angle sensor that measures an absolute rotation angle of the cam shaft,
The controller is
Based on the rotation angle of the cam shaft measured by the cam angle measuring unit, the control at the start is started,
The crank angle measurement unit is configured as an absolute angle sensor that measures an absolute rotation angle of the crankshaft,
The controller is
The start-up control is started based on both the rotation angle of the crankshaft measured by the crank angle measurement unit and the rotation angle of the camshaft measured by the cam angle measurement unit. variable valve system that. The variable valve system according to any one of claims 1 to 3 , wherein the start-up control includes ignition control for adjusting ignition in the internal combustion engine. The variable valve system according to any one of claims 1 to 3 , wherein the start-up control includes injection control for adjusting fuel injection in the internal combustion engine. Wherein the start control is characterized in that the relative rotation is the angle camshaft phase of the camshaft relative to the crankshaft includes a camshaft phase control to match the target value, according to claim 1 to 3 The variable valve system according to any one of the above. The cam shaft phase control calculates the cam shaft phase based on both the rotation angle of the crank shaft measured by the crank angle measurement unit and the rotation angle of the cam shaft measured by the cam angle measurement unit. The variable valve system according to claim 6 , wherein the variable valve system is performed by feeding back the calculated camshaft phase.

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