JP4123127B2 - Variable valve timing control device for internal combustion engine - Google Patents

Description

  The present invention relates to a variable valve timing control device that varies the valve timing of an intake valve or an exhaust valve of an internal combustion engine.

In recent years, internal combustion engines mounted on vehicles are increasingly using variable valve timing devices that vary the valve timing of intake valves and exhaust valves for the purpose of improving output, reducing fuel consumption, and reducing exhaust emissions. . Currently, a variable valve timing device that is in practical use varies the rotational phase of the cam shaft with respect to the crankshaft of the internal combustion engine (hereinafter referred to as “camshaft phase”), so that an intake valve or exhaust valve that is driven to open and close by the camshaft. There are many things that change the valve timing of the valve. At this time, as a method of detecting the actual valve timing (actual cam shaft phase), for example, as described in Patent Document 1 (Japanese Patent Laid-Open No. 2001-355462), a crank angle sensor is used for each predetermined crank angle. There are some which calculate the actual valve timing based on the output crank angle signal and the cam angle signal output by the cam angle sensor for each predetermined cam angle.
JP 2001-355462 A (Page 7 etc.)

  However, in the conventional valve timing calculation method, the actual valve timing is calculated during the period from when the previous cam angle signal is output until the next cam angle signal is output (that is, the period during which the cam angle signal is not output). Therefore, even if the actual valve timing changes continuously, the calculated value of the actual valve timing can only be updated step by step, and the variable valve timing control accuracy decreases accordingly. There was a drawback of doing.

  In addition, many of the variable valve timing devices that are currently in practical use use hydraulic pressure as the drive source. However, with this hydraulic drive system, when the engine is cold or when the engine is started, the hydraulic pressure is insufficient or the response of the hydraulic control is low. However, there is a disadvantage that the variable valve timing control accuracy is lowered, and therefore, there is one using a motor as a drive source of the variable valve timing device (for example, see Japanese Utility Model Publication No. 4-105906).

  However, this motor-driven variable valve timing device has a configuration in which the entire motor rotates integrally with a sprocket that is driven to rotate by a crankshaft. Therefore, the inertia weight of the rotating system of the variable valve timing device increases and the variable valve timing device becomes variable. There is a drawback that the durability of the timing device is reduced. Moreover, in order to connect the rotating motor and the external electrical wiring, a sliding contact type connection structure using a brush or the like must be used, which also causes a decrease in durability. Furthermore, the conventional motor-driven variable valve timing apparatus has the disadvantages that the configuration is generally complicated and the cost is high.

  The present invention has been made in consideration of these circumstances. Therefore, the object of the present invention is to meet the demands for improving the durability and reducing the cost of the variable valve timing device, while the cam angle signal is not output. Another object of the present invention is to provide a variable valve timing control device for an internal combustion engine that can calculate an actual valve timing and improve the variable valve timing control accuracy.

In order to achieve the above object, the variable valve timing device used in the invention according to claim 1 has a rotational speed that is 1/2 of the rotational speed of the crankshaft. The cam shaft phase is changed by adjusting the rotation speed of the motor with respect to the rotation speed ) . Specifically, as in claim 2, a first rotating member disposed concentrically with the camshaft and driven to rotate by the rotational driving force of the crankshaft, and a second rotating integrally with the camshaft. And a phase variable member that transmits the rotational force of the first rotating member to the second rotating member and changes the rotational phase of the second rotating member with respect to the first rotating member. A motor arranged concentrically with the camshaft to control the rotational phase of the phase variable member, and when the valve timing is not changed, the rotational speed of the motor matches the rotational speed of the first rotating member. by the variable phase member at a turning rate to match the rotational speed of the first rotary member, a rotational phase difference between the first rotary member and the second rotary member and the status quo Maintain the cam shaft phase When changing the timing is the rotational speed of the motor is varied with respect to the rotational speed of the first rotating member, changes the rotation speed of the phase changing member with respect to the rotational speed of said first rotary member Thus, the cam shaft phase is changed by changing the difference in rotational phase between the first rotating member and the second rotating member.

  In this configuration, since it is not necessary to rotate the entire motor, the inertia weight of the rotating system of the variable valve timing device can be reduced, and the motor and the external electric wiring are directly connected by a fixed connecting means. In general, the durability of the variable valve timing device can be improved. In addition, the configuration of the variable valve timing device is relatively simple, and the demand for cost reduction can be satisfied.

As in the present invention, in the variable valve timing device that changes the valve timing by changing the rotational speed of the motor with respect to the rotational speed that is 1/2 the rotational speed of the crankshaft (= the rotational speed of the first rotating member) . Since the valve timing change amount (cam shaft phase change amount) changes according to the difference between the motor rotation speed and the cam shaft rotation speed, the valve is changed based on the difference between the motor rotation speed and the cam shaft rotation speed. The amount of timing change can be calculated.

Focusing on this point, in the invention according to claim 1, every time the cam angle signal is output from the cam angle sensor, the cam angle signal is output based on the cam angle signal and the crank angle signal output from the crank angle sensor. In addition to calculating the actual valve timing at the time of signal output, the valve timing change amount is calculated based on the difference between the motor rotation speed and a half of the crankshaft rotation speed at a predetermined calculation cycle. In the calculation cycle, the final actual valve timing is calculated based on the actual valve timing when the cam angle signal is output and the valve timing change amount.

  Specifically, as in claim 3, the valve timing change amount per calculation cycle is calculated and the calculated values are integrated, and the integrated value of the valve timing change amount is calculated every time the cam angle signal is output. The final actual valve timing may be obtained by resetting and adding the integrated value of the subsequent valve timing change amount to the calculated value of the actual valve timing when the latest cam angle signal is output.

  As in the present invention, the valve timing change amount calculated based on the difference between the rotation speed of the motor and the rotation speed of the camshaft can be calculated even during a period in which the cam angle signal is not output. If the amount of valve timing change after the latest cam angle signal is output is calculated during the period when the latest cam angle signal is output, the valve timing change amount after that is added to the actual valve timing when the latest cam angle signal is output. Timing can be obtained with high accuracy. This makes it possible to calculate the actual valve timing continuously and accurately even during a period in which the cam angle signal is not output, thereby improving the variable valve timing control accuracy.

  By the way, it is conceivable that the rotational speed of the camshaft used when calculating the valve timing change amount is calculated based on the output period of the cam angle signal. In general, the number of cam angle signals output per camshaft rotation is considered. Therefore, it is difficult to detect the fluctuation of the rotational speed of the camshaft that varies with the explosion stroke of each cylinder from the output period of the cam angle signal. On the other hand, the number of crank angle signals output from the crank angle sensor is much larger than the number of cam angle signals. Therefore, if the crank angle signal is used, the rotational speed of the crankshaft varies with the explosion stroke of each cylinder. Fluctuations can be detected.

Therefore, considering the relationship of the cam shaft rotates one while the crankshaft rotates twice, the rotational speed of the crankshaft is detected based on the output cycle of the crank angle signal of crank angle sensor half of It is better to use a value. In this way, it is possible to calculate the amount of change in valve timing using the camshaft rotation speed, which is more accurate than when detecting the camshaft rotation speed from a small cam angle signal. Can be improved.

During stop of the internal combustion engine, the rotational speed of the camshaft is zero, as in claim 4, during stop of the internal combustion engine, the calculated value of the actual valve timing at the time of stop, subsequent valve timing It is preferable that the final actual valve timing is obtained by adding the integrated value of the change amount, or the final actual valve timing is obtained from the integrated value of the change amount of the valve timing from the reference position. As a result, the actual valve timing can be accurately calculated even when the internal combustion engine is stopped, and the actual valve timing can be controlled to the target value even when the internal combustion engine is stopped. Even when the actual valve timing at the time of stop is unknown, the actual valve timing is calculated from the integrated value of the valve timing change from the mechanical reference position (for example, the most retarded position) or the reference position detected by other means. can do.

Further, in consideration of the fact that the cam angle signal is not output when the cam angle sensor fails, the actual valve timing at the time of the last cam angle signal output before the failure, as described in claim 5 , when the cam angle sensor fails. The final value of the valve timing is added to the calculated value to obtain the final actual valve timing, or the final actual valve timing is obtained from the integrated value of the valve timing change from the reference position. It is good to make it. As a result, even when the cam angle sensor fails, the actual valve timing can be calculated accurately, and the actual valve timing can be controlled to the target value even when the cam angle sensor fails. Even if the actual valve timing before the cam angle sensor failure is unknown, the actual valve timing is calculated by integrating the valve timing variation from the mechanical reference position (for example, the most retarded angle position) or the reference position detected by other means. Timing can be calculated.

By the way, in the first aspect of the invention, the valve timing change amount is calculated based on the difference between the rotation speed of the motor and the half of the rotation speed of the crankshaft . Although the final actual valve timing is calculated based on the actual valve timing, the amount of change in the rotation angle of the motor or data correlated therewith (hereinafter referred to as “motor rotation angle change amount data”) as in claim 6. And calculation of cam shaft rotation angle variation or data correlated therewith (hereinafter referred to as “cam shaft rotation angle variation data”), and motor rotation angle variation data and cam shaft rotation. The valve timing change amount is calculated based on the difference from the angle change amount data, and based on the valve timing change amount and the actual valve timing when the cam angle signal is output. Final specific actual valve timing may be calculated.

Thus, even if the difference between the rotation angle change data of the motor and the rotation angle change data of the cam shaft is used, the difference between the rotation speed of the motor and the rotation speed of the cam shaft is evaluated, Can be calculated. Therefore, even if it is set as Claims 6-8 , the effect similar to the said Claims 1-3 can be acquired.

In this case, as according to claim 9, as the rotation angle change amount data of the motor, may be calculated the variation of the count value of the motor angle signal counter which counts based on the number of output times of the motor angle signal. The amount of change in the count value of the motor angle signal counter is data that accurately reflects the amount of change in the rotation angle of the motor.

Further, as described in claim 10, the amount of change in the count value of the crank angle signal counter that counts based on the number of output of the crank angle signal may be calculated as the amount of change in cam shaft rotation angle. Since the camshaft rotates once while the crankshaft rotates twice, ½ of the crankshaft rotation angle change amount corresponds to the camshaft rotation angle change amount. Therefore, the change amount of the count value of the crank angle signal counter is data that accurately reflects the change amount of the cam shaft rotation angle. According to the tenth aspect of the present invention, the valve timing change amount is calculated using the cam shaft rotation speed change amount data more accurate than the case of calculating the cam shaft rotation speed change amount data from a small cam angle signal. Thus, the calculation accuracy of the actual valve timing can be improved.

Further, in the case of calculating the valve timing variation amount based on a difference between the rotation angle variation data of rotation angle change amount data and the camshaft of the motor is also, as in claim 11, in the internal combustion engine is stopped, stop The final actual valve timing is obtained by adding the integrated value of the subsequent valve timing change to the calculated actual valve timing at the time, or the final actual value is calculated using the integrated value of the valve timing change from the reference position. The valve timing may be obtained. Thus, the same effect as in the fourth aspect can be obtained.

Further, as described in claim 12 , when the cam angle sensor fails, the integrated value of the subsequent valve timing variation is added to the calculated value of the actual valve timing when the last cam angle signal is output before the failure. The actual actual valve timing may be obtained or the final actual valve timing may be obtained from the integrated value of the change amount of the valve timing from the reference position. Thereby, the same effect as in the fifth aspect can be obtained.

  Hereinafter, two embodiments 1 and 2 in which 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. First, a schematic configuration of the entire system will be described with reference to FIG. The engine 11, which is an internal combustion engine, transmits power from the crankshaft 12 to the intake side camshaft 16 and the exhaust side camshaft 17 through the sprockets 14 and 15 by the timing chain 13 (or timing belt). It has become. A motor-driven variable valve timing device 18 is provided on the intake side camshaft 16 side. The variable valve timing device 18 varies the rotational phase (cam shaft phase) of the intake side camshaft 16 with respect to the crankshaft 12, thereby opening and closing the valve of an intake valve (not shown) driven by the intake side camshaft 16. The timing is variable.

  A cam angle sensor 19 that outputs a cam angle signal for each predetermined cam angle is attached to the outer peripheral side of the intake cam shaft 16. On the other hand, a crank angle sensor 20 that outputs a crank angle signal for each predetermined crank angle is attached to the outer peripheral side of the crankshaft 12.

  Next, a schematic configuration of the variable valve timing device 18 will be described with reference to FIG. The variable phase timing mechanism 21 of the variable valve timing device 18 includes an outer gear 22 (first rotating member) with internal teeth disposed concentrically with the intake camshaft 16, and concentrically on the inner peripheral side of the outer gear 22. The inner gear 23 with external teeth (second rotating member) is disposed, and the planetary gear 24 (phase variable member) is disposed between the outer gear 22 and the inner gear 23 and meshes with both. The outer gear 22 is provided so as to rotate integrally with the sprocket 14 that rotates in synchronization with the crankshaft 12, and the inner gear 23 is provided so as to rotate integrally with the intake side camshaft 16. Further, the planetary gear 24 functions to transmit the rotational force of the outer gear 22 to the inner gear 23 by turning around the inner gear 23 in a state of meshing with the outer gear 22 and the inner gear 23, and also to play the inner gear 23. The rotational phase (cam shaft phase) of the inner gear 23 with respect to the outer gear 22 is adjusted by changing the turning speed (revolution speed) of the planetary gear 24 with respect to the rotational speed of 23 (the rotational speed of the intake camshaft 16). ing.

  On the other hand, the engine 11 is provided with a motor 26 for changing the turning speed of the planetary gear 24. The rotation shaft 27 of the motor 26 is arranged coaxially with the intake side cam shaft 16, the outer gear 22 and the inner gear 23, and the rotation shaft 27 of the motor 26 and the support shaft 25 of the planetary gear 24 are connected to extend in the radial direction. It is connected via a member 28. Thus, as the motor 26 rotates, the planetary gear 24 can turn (revolve) on the circular orbit on the outer periphery of the inner gear 23 while rotating (spinning) around the support shaft 25. Further, a motor rotation speed sensor 29 (see FIG. 1) for detecting the rotation speed RM of the motor 26 (the rotation speed of the rotation shaft 27) is attached to the motor 26.

  The variable valve timing device 18 matches the rotation speed RM of the motor 26 with the rotation speed RC of the intake camshaft 16 and matches the revolution speed of the planetary gear 24 with the rotation speed of the inner gear 23 (rotation speed of the outer gear 22). As a result, the current rotational phase difference between the outer gear 22 and the inner gear 23 is maintained, and the current valve timing (cam shaft phase) is maintained.

Then, in the case of advancing the valve timing of the intake valve controls the rotation speed RM of the motor 26 so that the rotational speed RM of the motor 26 becomes faster than the rotation speed RC of the intake camshaft 16, the planetary gears The revolution speed of 24 is made faster than the rotation speed of the inner gear 23. As a result, the rotational phase of the inner gear 23 with respect to the outer gear 22 is advanced, and the valve timing (cam shaft phase) is advanced.

On the other hand, in the case of retarding the valve timing of the intake valve controls the rotation speed RM of the motor 26 so that the rotational speed RM of the motor 26 is slower than the rotation speed RC of the intake camshaft 16, the planetary gears The revolution speed of 24 is made slower than the rotational speed of the inner gear 23. Thereby, the rotation phase of the inner gear 23 with respect to the outer gear 22 is retarded, and the valve timing is retarded.

  Outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as “ECU”) 30. The ECU 30 is mainly composed of a microcomputer, and executes various engine control programs stored in its ROM (storage medium), thereby injecting fuel from a fuel injection valve (not shown) according to the engine operating state. The amount and ignition timing of a spark plug (not shown) are controlled.

  Further, the ECU 30 executes a variable valve timing control program (not shown) to feedback control the variable valve timing device 18 so that the actual valve timing of the intake valve matches the target valve timing.

  At that time, the ECU 30 executes the actual valve timing calculation program shown in FIGS. 3 to 5, and based on the crank angle signal output from the crank angle sensor 20 and the cam angle signal output from the cam angle sensor 19. The actual valve timing VTC at the time of sensor output is calculated, and the valve timing change amount ΔVT is calculated based on the difference between the rotational speed RM of the motor 26 and the rotational speed RC of the intake side camshaft 16 to output the cam angle signal. The final valve timing VT is obtained by adding the subsequent valve timing variation ΔVT to the actual valve timing VTC.

  The actual valve timing calculation program shown in FIGS. 3 to 5 is executed every predetermined time after an ignition switch (not shown) is turned on. When this program is started, first, at step 101, it is determined whether or not the engine is rotating, for example, whether or not the engine rotational speed calculated from the output period of the crank angle signal output from the crank angle sensor 20 is zero. Judge by.

  If it is determined that the engine is rotating, the routine proceeds to step 102, where it is determined whether or not the cam angle sensor 19 is normal based on a failure diagnosis result by a cam angle sensor failure diagnosis program (not shown).

  As a result, if it is determined that the cam angle sensor 19 is normal (no failure), the process proceeds to step 103 to determine whether or not the cam angle signal output from the cam angle sensor 19 has been input.

  When it is determined that the cam angle signal has been input, the routine proceeds to step 104, where the cam angle signal input time Tcam is stored in the memory (not shown) of the ECU 30, and then the routine proceeds to step 105, where The crank angle signal input time Tcrk output from the angle sensor 20 is stored in the memory.

Thereafter, the process proceeds to step 106, and the time difference TVT of the cam angle signal with respect to the crank angle signal is calculated by the following equation.
TVT = Tcrk-Tcam + K
Here, K is a correction amount for correcting a difference in response delay between the cam angle sensor 19 and the crank angle sensor 20.

Then, in the next step 107, using the time difference TVT of the cam angle signal with respect to the crank angle signal, the rotational phase VTB of the cam angle signal with respect to the crank angle signal is calculated by the following equation.
VTB = TVT / T120 x120 ° C A
Here, T120 is the time required for the crankshaft 12 to rotate 120 ° C. A, and is calculated based on the output signal of the crank angle sensor 20.

Thereafter, the process proceeds to step 108 to determine whether or not the valve timing is controlled to the reference position (for example, the most retarded position). If the valve timing is the reference position, the process proceeds to step 109. After learning the rotation phase (cam shaft phase) VTB of the cam angle signal with respect to the current crank angle signal as the reference position (reference cam shaft phase) VTBK of the rotation phase of the intake side cam shaft 16 with respect to the crankshaft 12, step 110 follows. move on.
VTBK = VTB
On the other hand, if it is determined in step 108 that the valve timing is not the reference position, the process proceeds to step 110 without performing the reference position learning process in step 109.

In this step 110, using the rotation phase VTB of the cam angle signal with respect to the current crank angle signal and the reference position VTBK, the rotation phase VTC of the cam angle signal with respect to the reference position VTBK is calculated, and this is calculated as the cam angle signal. The actual valve timing VTC at the time of output is assumed.
VTC = VTB-VTBK

  The processing of these steps 103 to 110 serves as valve timing calculation means at the time of cam angle signal output in the claims, and each time the cam angle signal is input (output), the cam angle signal and the crank angle are processed. The actual valve timing VTC when the cam angle signal is output is calculated based on the signal.

Thereafter, the process proceeds to step 111, and each time the actual valve timing VTC at the time of cam angle signal output is calculated (every cam angle signal is input), both valve timing variations ΔVTH and ΔVTS described later are “0”. Then, the process proceeds to step 119, where the final actual valve timing VT is calculated by the following equation.
VT = VTC + ΔVTH + ΔVTS
When the cam angle signal is input (output), ΔVTH = 0 and ΔVTS = 0 by the reset process in step 111, so that VT = VTC.

On the other hand, if it is determined in step 103 that the cam angle signal is not input, the process proceeds to step 112 in FIG. 4 and the rotational speed RM [rpm] of the motor 26 and the intake camshaft 16 are A rotational speed difference DMC [rpm] with respect to the rotational speed RC [rpm] is calculated.
DMC = RM-RC

In this case, the rotational speed RC of the intake camshaft 16 is a value of the rotational speed of the crankshaft 12 (engine rotational speed) × ½ calculated based on the output period of the crank angle signal output from the crank angle sensor 20. Is used.
Camshaft rotational speed RC = Crankshaft rotational speed × 1/2

Thereafter, the process proceeds to step 113, where the rotational speed difference DMC [rpm] is converted into a rotational difference RVT [rev / s] per second.
RVT = DMC / 60

In the next step 114, the valve timing change amount dVTH per calculation period (execution period of this program) P [s] of the valve timing change amount ΔVTH is calculated by the following equation.
dVTH = RVT / G × 720 ° C. A × P
Here, G is a reduction ratio of the phase variable mechanism 21 and is a ratio between a relative rotation amount of the motor 26 with respect to the intake camshaft 16 and a valve timing change amount (camshaft phase change amount).

Thereafter, the routine proceeds to step 115, where the valve timing change amount dVTH per calculation cycle P is integrated to calculate the valve timing change amount ΔVTH.
ΔVTH = ΔVTH + dVTH

  The processing in these steps 112 to 115 serves as valve timing change amount calculation means in the claims, and integrates the valve timing change amount dVTH per calculation period P during a period when the cam angle signal is not input. Thus, the valve timing change amount ΔVTH after the latest cam angle signal is output is obtained.

  Further, even when it is determined in step 102 in FIG. 3 that the cam angle sensor 19 has failed, the processing of these steps 112 to 115 is executed, so that the cam angle sensor 19 is failed per operation period P. The valve timing change amount dVTH is integrated to obtain the valve timing change amount ΔVTH from the time when the last cam angle signal is output before failure of the cam angle sensor 19 to the present time.

After calculating the valve timing change amount ΔVTH, the process proceeds to step 119 in FIG. 3 to calculate the final actual valve timing VT by the following equation.
VT = VTC + ΔVTH + ΔVTS
When the cam angle sensor 19 fails, ΔVTS = 0, so that VT = VTC + ΔVTH.

On the other hand, if it is determined in step 101 that the engine is stopped, the process proceeds to step 116 in FIG. 5, and only the rotation speed RM [rpm] of the motor 26 is used to determine the rotation difference RVT [rev / s / sec]. ] Is calculated.
RVT = RM / 60

Thereafter, the process proceeds to step 117, where the valve timing change amount dVTS per calculation period (that is, the execution period of this program) P [s] of the valve timing change amount ΔVTS is calculated by the following equation.
dVTS = RVT / G × 720 ° C. A × P
Here, G is a reduction ratio of the phase variable mechanism 21.

Thereafter, the process proceeds to step 118, where the valve timing change amount dVTS per calculation period P is integrated to obtain the valve timing change amount ΔVTS from the last cam angle signal output before the stop to the present time.
ΔVTS = ΔVTS + dVTS
The processing in these steps 116 to 118 also serves as valve timing change amount calculation means in the claims.

After calculating the valve timing change amount ΔVTS, the process proceeds to step 119 in FIG. 3 to calculate the final actual valve timing VT by the following equation.
VT = VTC + ΔVTH + ΔVTS
Since ΔVTH = 0 while the engine is stopped, VT = VTC + ΔVTS.
Note that the processing of the step 119 serves as final valve timing calculation means in the claims.

  With the above processing, every time the cam angle signal is input during engine rotation, the actual valve timing VTC when the cam angle signal is output is calculated based on the cam angle signal and the crank angle signal. When the cam angle signal is input (output), the valve timing change amounts ΔVTH and ΔVTS are reset to 0 by the reset process in step 111, so that the actual valve timing VTC at the time of cam angle signal output is the final value. The actual valve timing VT is obtained.

  On the other hand, during the period in which the cam angle signal is not input, the valve timing change amount dVTH per calculation cycle is calculated and integrated based on the rotational speed difference DMC between the motor 26 and the intake camshaft 16 to obtain the latest cam angle signal. The final actual valve timing VT is obtained by adding the subsequent valve timing variation ΔVTH (the integrated value of dVTH) to the actual valve timing VTC at the time of output. As a result, the actual valve timing VT can be calculated continuously and accurately even during a period in which the cam angle signal is not output, and the variable valve timing control accuracy can be improved.

  Further, when the engine is stopped, the final valve timing change amount ΔVTS is added to the actual valve timing VTC when the last cam angle signal is output before the stop to obtain the final actual valve timing VT. Even when the engine is stopped, the actual valve timing VT can be calculated with high accuracy, and even when the engine is stopped, the actual valve timing VT can be controlled to the target value.

  When the cam angle sensor 19 fails, the final actual valve timing VT is obtained by adding the subsequent valve timing variation ΔVTH to the actual valve timing VTC when the last cam angle signal is output before the failure. Therefore, even when the cam angle sensor 19 fails, the actual valve timing VT can be accurately calculated. Even when the cam angle sensor 19 fails, the actual valve timing VT can be controlled to the target value.

  When the engine is stopped or the cam angle sensor 19 fails, the actual valve timing is calculated from the integrated value of the valve timing change from the mechanical reference position (for example, the most retarded position) or the reference position detected by other means. You may make it do.

Further, the variable valve timing device 18 of the first embodiment includes an outer gear 22 (first rotating member) that is arranged concentrically with the camshaft 16 and is rotationally driven by the rotational driving force of the crankshaft 12, and the camshaft 16. An inner gear 23 (second rotating member) that rotates integrally with the planetary gear 24, and a planetary gear 24 (phase variable) that transmits the rotational force of the outer gear 22 to the inner gear 23 and changes the relative rotational phase between the two gears 22, 23. Member) and a motor 26 for turning the planetary gear 24 along a circular orbit concentric with the camshaft 16. When the valve timing is not changed, the rotational speed of the motor 26 is matched with the rotational speed of the outer gear 22. Te, by matching the rotation speed of the planet gear 24 to the rotational speed of the outer gear member 22, to maintain current the rotational phase difference between outer gear 22 and inner gear 23 The beam axis phase maintained as, when changing the valve timing, the rotational speed of the motor 26 is varied with respect to the rotational speed of the outer gear 22, changing the turning speed of planetary gear 24 with respect to the rotational speed of the outer gear member 22 By doing so, the cam shaft phase is changed by changing the difference in rotational phase between the outer gear 22 and the inner gear 23. In this configuration, since it is not necessary to rotate the entire motor 26, the inertia weight of the rotating system of the variable valve timing device 18 can be reduced, and the motor 26 and external electric wiring can be connected by a fixed connecting means. It can be directly connected, and generally the durability of the variable valve timing device 18 can be improved. In addition, the configuration of the variable valve timing device 18 is relatively simple and can meet the demand for cost reduction.

  Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the motor rotation speed sensor 29 serves as a motor angle sensor that outputs a motor angle signal each time the rotation shaft 27 of the motor 26 rotates by a predetermined rotation angle. Further, the ECU 30 serves as a crank angle signal counter that counts based on the number of output of the crank angle signal, and also serves as a motor angle signal counter that counts based on the number of output of the motor angle signal.

  In the first embodiment, the valve timing change amount ΔVT is calculated based on the difference between the rotational speed RM of the motor 26 and the rotational speed RC of the intake side camshaft 16. The change amount of the count value of the motor angle signal is used as data correlating with the rotation angle change amount, and the change amount of the count value of the crank angle signal is used as data correlating with the rotation angle change amount of the intake side camshaft 16. The valve timing change amount ΔVT is calculated based on the difference between the change amount of the count value of the angle signal and the change amount of the count value of the crank angle signal.

  The actual valve timing calculation program of FIG. 6 to FIG. 8 executed in the second embodiment is the same as the processing of FIG. 4 in the actual valve timing calculation program of FIG. 3 to FIG. 5 described in the first embodiment. 5 is changed to the process of FIG. 8, and the process of FIG. 6 is substantially the same as the process of FIG.

  When this program is started, if it is determined in step 103 in FIG. 6 that the cam angle signal has not been input, the process proceeds to step 201 in FIG. 7, and the count value of the crank angle signal (or the motor angle signal). The count value). Thus, even when the number of output of the crank angle signal per two rotations of the crankshaft 12 (per one rotation of the intake side camshaft 16) and the number of output of the motor angle signal per one rotation of the motor 26 are different, The count value of the crank angle signal per two revolutions of the shaft 12 (per revolution of the intake camshaft 16) and the count value of the motor angle signal per revolution of the motor 26 are set to be the same.

Thereafter, the routine proceeds to step 202, where the change amount ΔCcr of the crank angle signal count value (data correlated with the change amount of the rotation angle of the intake camshaft 16) is calculated by the following equation.
ΔCcr = Ccr (i) −Ccr (i−1)

  Here, Ccr (i) is a count value of the crank angle signal at the current calculation, and Ccr (i-1) is a count value of the crank angle signal at the previous calculation. The process of step 202 serves as a cam shaft rotation angle change amount data calculation means in the claims.

Thereafter, the process proceeds to step 203, and the change amount ΔCmo (data correlated with the rotation angle change amount of the motor 26) of the count value of the motor angle signal is calculated by the following equation.
ΔCmo = Cmo (i) -Cmo (i-1)
Here, Cmo (i) is the count value of the motor angle signal at the current calculation, and Cmo (i-1) is the count value of the motor angle signal at the previous calculation. The processing in step 203 serves as a motor rotation angle change amount data calculation means in the claims.

Thereafter, the process proceeds to step 204, where a difference C between the change amount ΔCmo of the count value of the motor angle signal and the change amount ΔCcr of the count value of the crank angle signal is calculated.
C = ΔCmo−ΔCcr

Thereafter, the process proceeds to step 205, where the difference C between the change amounts of the count values of the motor angle signal and the crank angle signal is converted into the rotation angle change amount D of the motor 26 relative to the intake side camshaft 16 by the following equation.
D = C × D0

  Here, D0 is a conversion coefficient, and corresponds to the rotation angle change amount of the motor 26 with respect to the intake side camshaft 16 when the difference C between the change values of the count values of the motor angle signal and the crank angle signal is 1 count.

In the next step 206, the rotation angle change amount D of the motor 26 relative to the intake camshaft 16 is converted into a valve timing change amount dVTH per calculation cycle (execution cycle of this program) by the following equation.
dVTH = D / G
Here, G is a reduction ratio of the phase variable mechanism 21 and is a ratio between a relative rotation amount of the motor 26 with respect to the intake camshaft 16 and a valve timing change amount (camshaft phase change amount).

Thereafter, the process proceeds to step 207, where the valve timing change amount dVTH per calculation cycle is integrated to obtain the valve timing change amount ΔVTH after the latest cam angle signal is output.
ΔVTH = ΔVTH + dVTH

  In addition, when it is determined in step 102 in FIG. 6 that the cam angle sensor 19 has failed, the processes of steps 201 to 207 are executed, so that the cam angle sensor 19 fails during the operation period. The valve timing change amount dVTH is integrated to obtain the valve timing change amount ΔVTH from the last cam angle signal output before the cam angle sensor 19 failure until the present time.

After calculating the valve timing change amount ΔVTH, the process proceeds to step 119 in FIG. 6 to calculate the final actual valve timing VT by the following equation.
VT = VTC + ΔVTH + ΔVTS
When the cam angle sensor 19 fails, ΔVTS = 0, so that VT = VTC + ΔVTH.

On the other hand, if it is determined in step 101 of FIG. 6 that the engine is stopped, the process proceeds to step 208 of FIG. 8 to calculate the change amount ΔCmo of the count value of the motor angle signal by the following equation.
ΔCmo = Cmo (i) -Cmo (i-1)

Thereafter, the process proceeds to step 209, where the change amount ΔCmo of the count value of the motor angle signal is converted into a rotation angle change amount D of the motor 26 with respect to the intake side camshaft 16 by the following equation.
D = C × D0

In the next step 210, the rotation angle change amount D of the motor 26 with respect to the intake camshaft 16 is converted into a valve timing change amount dVTS per calculation cycle by the following equation.
dVTS = D / G

Thereafter, the process proceeds to step 211, where the valve timing change amount dVTS per calculation cycle is integrated to obtain the valve timing change amount ΔVTS from the last cam angle signal output before the stop to the present time.
ΔVTS = ΔVTS + dVTS

After calculating the valve timing change amount ΔVTS, the process proceeds to step 119 in FIG. 6 to calculate the final actual valve timing VT by the following equation.
VT = VTC + ΔVTH + ΔVTS
Since ΔVTH = 0 while the engine is stopped, VT = VTC + ΔVTS.

  When the engine is stopped or the cam angle sensor 19 fails, the actual valve timing is calculated from the integrated value of the valve timing change from the mechanical reference position (for example, the most retarded position) or the reference position detected by other means. You may make it do.

  With the above processing, in the second embodiment, as shown in the time chart of FIG. 9, every time the cam angle signal is input during engine rotation, the cam angle signal is output based on the cam angle signal and the crank angle signal. The actual valve timing VTC is calculated. When the cam angle signal is input (output), the actual valve timing VTC when the cam angle signal is output becomes the final actual valve timing VT as it is.

  On the other hand, during the period when the cam angle signal is not input, the valve timing change amount dVTH per calculation cycle is calculated based on the difference C (= ΔCmo−ΔCcr) between the change amounts of the count values of the motor angle signal and the crank angle signal. The valve timing change amount ΔVTH is obtained by integrating the dVTH. Then, the final actual valve timing VT is obtained by adding the valve timing change amount ΔVTH to the actual valve timing VTC when the latest cam angle signal is output.

  Even in the case of the second embodiment described above, the same effect as that of the first embodiment can be obtained.

  In the second embodiment, the valve timing change amount ΔVT is calculated based on the difference C between the change amount ΔCmo of the count value of the motor angle signal and the change amount ΔCcr of the count value of the crank angle signal. The rotation angle change amount of the motor 26 is calculated based on the change amount ΔCmo of the count value of the angle signal, and the rotation angle change amount of the intake cam shaft 16 is calculated based on the change amount ΔCcr of the count value of the crank angle signal. The valve timing change amount ΔVT may be calculated based on the difference between the rotation angle change amount of the motor 26 and the rotation angle change amount of the intake camshaft 16.

  Further, the present invention is not limited to the variable valve timing control device for the intake valve, but may be applied to the variable valve timing control device for the exhaust valve. Furthermore, the phase variable mechanism of the variable valve timing device 18 is not limited to the one using the planetary gear mechanism as in the present embodiment, and other types of phase variable mechanisms may be used. Any motor-driven variable valve timing device that varies the valve timing by changing the speed with respect to the rotational speed of the cam shaft may be used.

It is a schematic block diagram of the whole control system in Example 1 of this invention. It is a schematic block diagram of a variable valve timing apparatus. It is a flowchart (the 1) which shows the flow of a process of the actual valve timing calculation program of Example 1. FIG. It is a flowchart (the 2) which shows the flow of a process of the actual valve timing calculation program of Example 1. 6 is a flowchart (No. 3) showing a flow of processing of an actual valve timing calculation program according to the first embodiment. It is a flowchart (the 1) which shows the flow of a process of the actual valve timing calculation program of Example 2. It is a flowchart (the 2) which shows the flow of a process of the actual valve timing calculation program of Example 2. It is a flowchart (the 3) which shows the flow of a process of the actual valve timing calculation program of Example 2. 10 is a time chart illustrating an execution example of the second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Crankshaft, 16 ... Intake side camshaft, 17 ... Exhaust camshaft, 18 ... Variable valve timing device, 19 ... Cam angle sensor, 20 ... Crank angle sensor, 21 ... Phase variable mechanism , 22 ... outer gear (first rotating member), 23 ... inner gear (second rotating member), 24 ... planetary gear (phase variable member), 26 ... motor, 27 ... rotating shaft, 29 ... motor rotation speed sensor (motor) Angle sensor), 30 ECU (valve timing calculation means at cam angle signal output, valve timing change amount calculation means, final valve timing calculation means, motor rotation angle change amount data calculation means, cam shaft rotation angle change amount data calculation means, (Crank angle signal counter, motor angle signal counter)

Claims (12)

A variable valve timing device that changes a valve timing of an intake valve or an exhaust valve driven to open and close by a camshaft by changing a rotational phase of a camshaft with respect to a crankshaft of an internal combustion engine (hereinafter referred to as "camshaft phase"). In what to control
The variable valve timing device is configured to change the camshaft phase by adjusting the rotation speed of a motor with respect to a rotation speed that is 1/2 of the rotation speed of the crankshaft,
A crank angle sensor that outputs a crank angle signal for each predetermined crank angle;
A cam angle sensor that outputs a cam angle signal for each predetermined cam angle;
A cam angle signal output valve timing calculating means for calculating an actual valve timing at the time of cam angle signal output based on the cam angle signal and the crank angle signal each time the cam angle signal is output;
A valve timing change amount calculating means for calculating a valve timing change amount based on a difference between a rotation speed of the motor and a half value of a rotation speed of the crankshaft at a predetermined calculation cycle;
A final valve timing calculating means for calculating a final actual valve timing based on a calculated value of the actual valve timing at the time of outputting the cam angle signal and a calculated value of the valve timing change amount at a predetermined calculation cycle. A variable valve timing control device for an internal combustion engine. The variable valve timing device includes a first rotating member that is arranged concentrically with the camshaft and is rotationally driven by a rotational driving force of the crankshaft, and a second rotating member that rotates integrally with the camshaft. A phase variable member that transmits a rotational force of the first rotating member to the second rotating member and changes a rotational phase of the second rotating member with respect to the first rotating member, and the phase variable member A motor arranged concentrically with the camshaft so as to control the rotational phase of the motor, and when the valve timing is not changed, the rotational speed of the motor is made to coincide with the rotational speed of the first rotating member. , By maintaining the rotational phase difference between the first rotating member and the second rotating member at present, by matching the turning speed of the phase variable member with the rotating speed of the first rotating member, Cam shaft position When the valve timing is changed, the rotational speed of the motor is changed with respect to the rotational speed of the first rotating member, and the turning speed of the phase variable member is changed to the first rotating member. The cam shaft phase is changed by changing a difference in rotational phase between the first rotating member and the second rotating member by changing the rotational speed of the cam shaft. The variable valve timing control device for an internal combustion engine according to claim 1. The valve timing change amount calculating means calculates a valve timing change amount per calculation cycle and integrates the calculated value, and resets the integrated value of the valve timing change amount every time the cam angle signal is output. And means for
The final valve timing calculation means is characterized in that the final actual valve timing is obtained by adding the integrated value of the valve timing change amount thereafter to the calculated value of the actual valve timing when the latest cam angle signal is output. The variable valve timing control device for an internal combustion engine according to claim 1 or 2. Whether the final valve timing calculation means obtains a final actual valve timing by adding an integrated value of the subsequent valve timing change amount to a calculated value of the actual valve timing at the time of stop while the internal combustion engine is stopped. or a variable valve timing control apparatus for an internal combustion engine according to any of claims 1 to 3 and obtaining the final actual valve timing from the reference position in the integrated value of the change amount of the valve timing. The final valve timing calculation means adds the integrated value of the subsequent valve timing change amount to the calculated value of the actual valve timing at the time of output of the last cam angle signal before the failure when the cam angle sensor fails. variable valve of an internal combustion engine according to any of claims 1 to 4, wherein the determination of the final actual valve timing in the integrated value of the specific actual valve Request timing or from a reference position of the valve timing variation Timing control device. A variable valve timing device that changes a valve timing of an intake valve or an exhaust valve driven to open and close by a camshaft by changing a rotational phase of a camshaft with respect to a crankshaft of an internal combustion engine (hereinafter referred to as "camshaft phase"). In what to control
The variable valve timing device is configured to change the camshaft phase by adjusting the rotation speed of a motor with respect to a rotation speed that is 1/2 of the rotation speed of the crankshaft,
A crank angle sensor that outputs a crank angle signal for each predetermined crank angle;
A cam angle sensor that outputs a cam angle signal for each predetermined cam angle;
Motor rotation angle change amount data calculating means for calculating the rotation angle change amount of the motor or data correlated therewith (hereinafter referred to as “motor rotation angle change amount data”);
Cam shaft rotation angle change amount data calculating means for calculating the cam shaft rotation angle change amount or data correlated therewith (hereinafter referred to as “cam shaft rotation angle change amount data”);
A cam angle signal output valve timing calculating means for calculating an actual valve timing at the time of cam angle signal output based on the cam angle signal and the crank angle signal each time the cam angle signal is output;
A valve timing change amount calculating means for calculating a valve timing change amount based on a difference between the rotation angle change data of the motor and the rotation angle change data of the camshaft at a predetermined calculation cycle;
A final valve timing calculating means for calculating a final actual valve timing based on a calculated value of the actual valve timing at the time of outputting the cam angle signal and a calculated value of the valve timing change amount at a predetermined calculation cycle. A variable valve timing control device for an internal combustion engine. The variable valve timing device includes a first rotating member that is arranged concentrically with the camshaft and is rotationally driven by a rotational driving force of the crankshaft, and a second rotating member that rotates integrally with the camshaft. A phase variable member that transmits a rotational force of the first rotating member to the second rotating member and changes a rotational phase of the second rotating member with respect to the first rotating member, and the phase variable member A motor arranged concentrically with the camshaft so as to control the rotational phase of the motor, and when the valve timing is not changed, the rotational speed of the motor is made to coincide with the rotational speed of the first rotating member. , By maintaining the rotational phase difference between the first rotating member and the second rotating member at present, by matching the turning speed of the phase variable member with the rotating speed of the first rotating member, Cam shaft position When the valve timing is changed, the rotational speed of the motor is changed with respect to the rotational speed of the first rotating member, and the turning speed of the phase variable member is changed to the first rotating member. The cam shaft phase is changed by changing a difference in rotational phase between the first rotating member and the second rotating member by changing the rotational speed of the cam shaft. The variable valve timing control device for an internal combustion engine according to claim 6 . The valve timing change amount calculating means calculates a valve timing change amount per calculation cycle and integrates the calculated value, and resets the integrated value of the valve timing change amount every time the cam angle signal is output. And means for
The final valve timing calculation means is characterized in that the final actual valve timing is obtained by adding the integrated value of the valve timing change amount thereafter to the calculated value of the actual valve timing when the latest cam angle signal is output. The variable valve timing control device for an internal combustion engine according to claim 6 or 7 . A motor angle sensor that outputs a motor angle signal each time the motor rotates by a predetermined rotation angle;
The motor rotation angle change amount data calculation means calculates, as the rotation angle change amount data of the motor, a change amount of a count value of a motor angle signal counter that counts based on the number of outputs of the motor angle signal. The variable valve timing control device for an internal combustion engine according to any one of claims 6 to 8 . The cam shaft rotation angle change amount data calculation means calculates a change amount of a count value of a crank angle signal counter that counts based on the number of outputs of the crank angle signal as the cam shaft rotation angle change amount data. 10. A variable valve timing control device for an internal combustion engine according to claim 6 , wherein the variable valve timing control device is an internal combustion engine. Whether the final valve timing calculation means obtains a final actual valve timing by adding an integrated value of the subsequent valve timing change amount to a calculated value of the actual valve timing at the time of stop while the internal combustion engine is stopped. The variable valve timing control apparatus for an internal combustion engine according to any one of claims 6 to 10 , wherein a final actual valve timing is obtained from an integrated value of a change amount of the valve timing from a reference position. The final valve timing calculation means adds the integrated value of the subsequent valve timing change amount to the calculated value of the actual valve timing at the time of output of the last cam angle signal before the failure when the cam angle sensor fails. 12. A variable valve for an internal combustion engine according to claim 6 , wherein a final actual valve timing is obtained or a final actual valve timing is obtained from an integrated value of a change amount of the valve timing from a reference position. Timing control device.

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