JP4840613B2 - Rotational state detection device for internal combustion engine - Google Patents

Description

  The present invention relates to an internal-combustion-engine rotational state detection device that has an improved internal-rotation-engine detection method.

  In a general engine control system, for example, as described in Patent Document 1 (Japanese Patent Laid-Open No. 60-240875), a crank angle sensor that outputs a pulse signal at every predetermined crank angle is provided, and the engine is operating. In addition, the engine speed is detected based on the interval (pulse frequency) of the pulse signal of the crank angle sensor.

  During engine operation, the cylinder is discriminated based on the output signals of the crank angle sensor and the cam angle sensor, and the crank angle is detected to control the ignition timing and the fuel injection timing. Until the cranking of the engine by the starter completes the determination of the specific cylinder (that is, until the signal of the predetermined crank angle of the specific cylinder is detected), there is a problem that the cylinder to be initially ignited / injected is unknown.

Therefore, as described in Patent Document 1 (Japanese Patent Application Laid-Open No. 60-240875), the crank angle (engine rotation stop position) detected by the crank angle sensor when the engine rotation is stopped is stored in a memory. When the engine is started, ignition control and fuel injection control are started with reference to the crank angle at the time of engine rotation stop stored in the memory until the signal of the predetermined crank angle of the specific cylinder is first detected. There is something that was made.
JP-A-60-240875 (pages 2 to 3 etc.)

  In recent years, in order to meet the demands for improved startability and improved exhaust emissions at start-up, there is a technology that improves the detection accuracy of the engine rotation stop position, and a technology that improves the engine rotation speed detection accuracy in the extremely low rotation region at the start of startup. It has become necessary.

  Generally, a crank angle sensor used in an engine control system is often an electromagnetic pickup type crank angle sensor in consideration of cost and the like, but this electromagnetic pickup type crank angle sensor is integrated with a crankshaft. Since the induced electromotive force generated with the rotation of the rotating signal rotor is output as a pulse signal, the rotation speed of the signal rotor is very slow. A pulse signal (induced electromotive force) cannot be output. For this reason, in the conventional system that detects the engine rotation speed and the engine rotation stop position based on the pulse signal of the electromagnetic pickup type crank angle sensor, the engine rotation speed and the engine rotation stop position in the extremely low rotation region can be accurately detected. I can't. In addition, the engine rotation reverses due to the compression pressure of the compression stroke just before the engine rotation stops, but the reverse rotation of the engine cannot be detected from the pulse signal of the crank angle sensor. Even with this phenomenon, there has been a problem that the detection error of the engine rotation stop position becomes large.

  In order to solve these drawbacks, there is a Hall sensor type crank angle sensor that uses a Hall sensor to detect the rotational position of the crankshaft instead of the electromagnetic pickup type crank angle sensor. The crank angle sensor of the type has a disadvantage that it is expensive.

  The present invention has been made in consideration of these circumstances. Therefore, the object of the present invention is to detect the rotational state of the internal combustion engine with high accuracy while satisfying the demand for cost reduction. An object of the present invention is to provide an internal combustion engine rotation state detection device capable of improving exhaust emission at the time of starting.

  In recent years, internal combustion engines mounted on vehicles have been increasing in number that employ variable valve timing devices for the purpose of improving output, reducing fuel consumption, reducing exhaust emissions, and the like. Many of these variable valve timing devices change the valve timing of intake valves and exhaust valves that are driven to open and close by the camshaft by changing the rotational phase of the camshaft with respect to the crankshaft (hereinafter referred to as “camshaft phase”). .

The present applicant is researching and developing a newly developed variable valve timing device using a motor as a drive source. This feature of the motor-driven variable valve timing apparatus, the rotation shaft of the drive motor camshaft phase is maintained current by rotating synchronously with the cam shaft during non-driving of the driving motor as a driving source, a driving motor And the cam shaft phase changes by changing the rotational speed of the drive motor with respect to the rotational speed of the cam shaft. In this variable valve timing device, in order to control the rotation speed and amount of the drive motor with high accuracy and to control the valve timing with high accuracy, such as a hall sensor that outputs a motor rotation position signal corresponding to the rotation position of the drive motor. It is necessary to provide a motor rotation position sensor.

Focusing on this point, the rotational state detection device for an internal combustion engine according to claim 1 of the present invention is a motor rotation according to the rotational position of the drive motor in a system equipped with the motor-driven variable valve timing device. A motor rotation position sensor that outputs a position signal is provided, and the rotation stop position of the internal combustion engine is detected based on the motor rotation position signal output from the motor rotation position sensor when the internal combustion engine is stopped and the drive motor is not driven. This is detected by means. Since the motor rotation position sensor can output a motor rotation position signal corresponding to the rotation position of the drive motor even when the rotation of the drive motor (rotation of the internal combustion engine) is stopped, the motor rotation position signal is output while the internal combustion engine is stopped. It is possible to detect the rotation stop position of the internal combustion engine with high accuracy. Further, since the rotation stop position of the internal combustion engine can be detected in a state where the internal combustion engine is stopped, it is not affected by reverse rotation just before the rotation stop of the internal combustion engine.

  In this case, when the internal combustion engine is stopped with the camshaft phase controlled to the most retarded position or the most advanced position as in claim 2, the rotation of the internal combustion engine is stopped based on the motor rotational position signal. The position may be detected. In this way, when the internal combustion engine is stopped with the rotational positional relationship between the rotational shaft of the drive motor and the cam shaft being fixed, the rotational stop position of the internal combustion engine is determined using the motor rotational position signal. Can be detected, and the detection accuracy of the rotation stop position of the internal combustion engine can be further improved.

  Hereinafter, the best mode for carrying out the present invention will be described using the following two Examples 1 and 2.

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 phase variable mechanism 21 of the variable valve timing device 18 includes an outer gear 22 with inner teeth arranged concentrically with the intake side camshaft 16, and an outer gear with outer teeth arranged concentrically on the inner peripheral side of the outer gear 22. An inner gear 23 and a planetary gear 24 disposed between the outer gear 22 and the inner gear 23 and meshing with each other are constituted. 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 drive motor 26 for changing the turning speed of the planetary gear 24. The rotation shaft 27 of the drive 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 drive motor 26 and the support shaft 25 of the planetary gear 24 are arranged in the radial direction. It is connected via an extending connecting member 28. Thus, as the drive motor 26 rotates, the planetary gear 24 can turn (revolve) the circular orbit on the outer periphery of the inner gear 23 while rotating (spinning) around the support shaft 25.

  The variable valve timing device 18 is configured such that when the drive motor 26 is not driven, the rotation shaft 27 of the drive motor 26 rotates in synchronization with the intake side camshaft 16, and the rotation speed RM of the drive motor 26 is set to the intake side. When the revolution speed of the planetary gear 24 matches the rotation speed of the inner gear 23 (the rotation speed of the outer gear 22) in accordance with the rotation speed RC of the camshaft 16, the difference in rotation phase between the outer gear 22 and the inner gear 23 is found. The current state is maintained, and the valve timing (cam shaft phase) is maintained as it is.

  When the valve timing of the intake valve is advanced, the rotational speed RM of the drive motor 26 is made faster than the rotational speed RC of the intake side camshaft 16, and the revolution speed of the planetary gear 24 is set to the rotational speed of the inner gear 23. Be faster. 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, when retarding the valve timing of the intake valve, the rotational speed RM of the drive motor 26 is made slower than the rotational speed RC of the intake side camshaft 16, and the revolution speed of the planetary gear 24 is set to the rotational speed of the inner gear 23. Slower than. Thereby, the rotation phase of the inner gear 23 with respect to the outer gear 22 is retarded, and the valve timing is retarded.

  Next, the configuration of the drive motor 26 will be described with reference to FIG. The drive motor 26 is, for example, a three-phase brushless motor, and the housing 29 of the drive motor 26 includes a substantially bottomed cylindrical case portion 30 and a lid portion 31 that closes the opening of the case portion 30. A substantially cylindrical stator 32 is fixed to the inner peripheral side of the housing 29. In the stator 32, windings 35 of respective phases are wound around a plurality of teeth portions provided on the stator core 33 via insulators 34, and a rotor 36 is rotatably accommodated on the inner peripheral side of the stator 32. Yes.

  The rotor 36 is formed by laminating a plurality of disk-shaped core sheets to form a rotor core 37, and a rotation shaft 27 is fitted into a through hole formed in the central portion of the rotor core 37 to rotate integrally with the rotor core 37. It is supposed to be. The rotary shaft 27 is rotatably supported by bearings 38 and 39 provided on the case portion 30 and the lid portion 31, respectively. A plurality of slit portions 40 are formed in the rotor core 37 at equal angular intervals in the circumferential direction, and permanent magnets 41 are embedded in the respective slit portions 40. Further, fixed plates 42 and 43 made of a non-magnetic material are provided on both end surfaces in the axial direction of the rotor core 37 so that the permanent magnet 41 is prevented from falling off by these fixed plates 42 and 43. .

  The drive motor 26 includes a motor rotation position sensor 44 that outputs a motor rotation position signal corresponding to the rotation position of the drive motor 26 (rotation position of the rotor 36). The motor rotation position sensor 44 includes a ring-shaped sensor magnet 45 and a hall element 46 disposed so as to face the sensor magnet 45. The sensor magnet 45 is fixed to the upper surface of the rotor 36 (fixed plate 43) and rotates integrally with the rotor 36, and the Hall element 46 is fixed to a control circuit board 47 provided on the lid portion 31.

  The motor rotational position sensor 44 changes the magnetic flux density linked to the Hall element 46 in accordance with the rotational position of the sensor magnet 45 that rotates integrally with the rotor 36, so that the Hall element 46 becomes the rotational position of the rotor 36. A corresponding motor rotation position signal is output. The control circuit board 47 rotates the rotor 36 by sequentially switching energization to the windings 35 of each phase of the stator 32 according to the rotational position of the rotor 36 detected based on the motor rotational position signal.

  Outputs of the various sensors described above are input to an engine control circuit (hereinafter referred to as “ECU”) 48. The ECU 48 is mainly composed of a microcomputer, and executes various engine control programs stored in its ROM (storage medium) to thereby inject 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 48 controls the variable valve timing device 18 (drive motor 26) so as to make the actual valve timing of the intake valve coincide with the target valve timing by executing a variable valve timing control program (not shown).

  Further, the ECU 48 executes the engine rotation state detection program shown in FIG. 4 so that when the engine rotation speed NE is greater than or equal to a predetermined value during engine operation, the engine rotation speed is based on the crank angle signal of the crank angle sensor 20. NE is detected, and when the engine rotational speed NE is lower than a predetermined value, the engine rotational speed NE and the engine rotational direction are detected based on the motor rotational position signal of the motor rotational position sensor 44. Further, while the engine is stopped, the engine rotation stop position (rotation stop position of the crankshaft 12) is detected based on the motor rotation position signal of the motor rotation position sensor 44.

  Hereinafter, the processing content of the engine rotation state detection program shown in FIG. 4 executed by the ECU 48 will be described. The engine rotation state detection program shown in FIG. 4 is executed at a predetermined cycle while the ECU 48 is powered on. Even after the ignition switch (not shown) is turned off, the ECU 48 is continuously energized for a while in order to execute this program.

  When this program is started, first, at step 101, the engine speed NE calculation request is turned on, and then the process proceeds to step 102, where whether or not the engine speed NE (for example, the previous detected value) is lower than a predetermined value. Determine. This predetermined value is set to a lower limit value of the engine speed at which the engine speed NE can be accurately calculated based on the crank angle signal of the crank angle sensor 20 or a value slightly higher than that (for example, 100 rpm).

  As a result, when it is determined that the engine rotational speed NE is equal to or higher than the predetermined value, it is determined that the accuracy of calculation of the engine rotational speed NE based on the crank angle signal of the crank angle sensor 20 can be ensured, and step 103 is performed. Then, based on the crank angle signal from the crank angle sensor 20, the engine speed NE is calculated.

  On the other hand, if it is determined in step 102 that the engine speed is lower than the predetermined value, it is determined that the accuracy of calculation of the engine speed NE based on the crank angle signal of the crank angle sensor 20 is reduced, and the step Proceeding to 104, the operation of the variable valve timing device 18 is prohibited, and the power supply to the drive motor 26 is stopped so that the current state of the camshaft phase is maintained. As a result, the intake side camshaft 16 that is rotationally driven by the crankshaft 12 and the rotation shaft 27 of the drive motor 26 rotate in synchronism, so that the rotation state of the drive motor 26 becomes information on the engine rotation state.

  Thereafter, the process proceeds to step 105, where it is determined whether the engine 11 is rotating forward or backward based on the behavior of the motor rotation position signal of the motor rotation position sensor 44, and then the process proceeds to step 106, where the motor rotation position is determined. An engine rotation speed NE is calculated based on a change speed of the motor rotation position signal of the sensor 44 or the like.

  Thereafter, the routine proceeds to step 107, where it is determined whether or not the engine has stopped based on whether or not the engine speed NE has become zero. When the engine speed NE has become zero, it is determined that the engine has been stopped. In step 108, the engine rotation stop position (crank angle) is calculated from the motor rotation stop position based on the motor rotation position signal of the motor rotation position sensor 44 when the engine is stopped. The processing in step 108 serves as stop position detection means in the claims.

  In the motor-driven variable valve timing device 18 according to the first embodiment, a motor rotation position sensor 44 that outputs a motor rotation position signal corresponding to the rotation position of the drive motor 26 is incorporated in the drive motor 26 and is not driven. Sometimes, the rotation shaft 27 of the drive motor 26 rotates in synchronism with the intake side camshaft 16, so that the rotation state of the drive motor 26 becomes information on the engine rotation state.

  Focusing on these points, in the first embodiment, when the energization to the drive motor 26 is stopped and the intake camshaft 16 and the rotation shaft 27 of the drive motor 26 are rotating in synchronization, the motor Since the engine rotation speed NE and the engine rotation direction are detected based on the output signal of the rotation position sensor 44, the engine rotation speed NE and the engine rotation direction (forward rotation / reverse rotation) can be accurately detected. The motor rotation position sensor 44 (a hall sensor composed of a sensor magnet 45 and a hall element 46) changes the motor rotation position signal in accordance with the rotation position of the drive motor 26, so the rotation speed (engine rotation speed) of the drive motor 26 is high. Even in a very low extremely low rotation region, the engine rotation speed NE can be detected with high accuracy from the motor rotation position signal. In addition, since the motor rotational position sensor 44 for the variable valve timing device 18 is also used as the rotational sensor for the engine rotational speed NE, the demand for cost reduction can be satisfied.

  Incidentally, the calculation load of the ECU 48 that calculates the engine rotation speed NE from the output signal of the motor rotation position sensor 44 increases as the engine rotation speed NE (output pulse frequency of the motor rotation position sensor 44) increases.

  In consideration of this point, in the first embodiment, in the rotation region where the rotation speed detection accuracy is ensured by the signal of the crank angle sensor 20, the rotation speed is detected using the signal of the crank angle sensor 20, Since the rotational speed detection is performed using the signal of the motor rotational position sensor 44 only in the rotational region where the rotational speed detection accuracy cannot be ensured by the signal of the crank angle sensor 20, the calculation load of the ECU 48 is reduced. be able to.

  Further, in the first embodiment, the motor rotation position sensor 44 can output a motor rotation position signal corresponding to the rotation position of the drive motor 26 even when the rotation of the drive motor 26 (engine rotation) is stopped. Since the engine rotation stop position is detected based on the motor rotation position signal of the motor rotation position sensor 44 while the engine is stopped, the motor rotation occurs while the engine is stopped without being affected by reverse rotation immediately before the engine rotation stops. The engine rotation stop position can be accurately detected from the position signal.

Next, Embodiment 2 of the present invention will be described with reference to FIG.
In the second embodiment, the cam shaft phase is controlled to the most retarded angle position or the most advanced angle position when the engine speed NE is lower than a predetermined value by executing the engine rotation state detection program shown in FIG. In this state, the engine rotational speed NE and the engine rotational direction are detected based on the signal from the motor rotational position sensor 44. Furthermore, the engine rotation stop position is detected based on the signal from the motor rotation position sensor 44 when the engine is stopped with the camshaft phase controlled to the most retarded angle position or the most advanced angle position.

  In the engine rotation state detection program of FIG. 5 executed in the second embodiment, when it is determined in step 102 that the engine rotation speed is lower than a predetermined value, the process proceeds to step 104a, where the camshaft phase is the most retarded position. Alternatively, by controlling the drive motor 26 of the variable valve timing device 18 so as to reach the most advanced position, the movable portion (not shown) of the variable valve timing device 18 is retarded or advanced on the stopper side (see FIG. (Not shown) to fix the camshaft phase at the most retarded position or the most advanced position. As a result, the rotational speed of the drive motor 26 and the rotational speed of the intake camshaft 16 are forcibly matched, and the rotational positional relationship between the rotational shaft 27 of the drive motor 26 and the camshaft is forcibly fixed. .

  Thereafter, the engine rotation direction is calculated based on the signal from the motor rotation position sensor 44, and the engine rotation speed NE is calculated based on the signal from the motor rotation position sensor 44 (steps 105 and 106). The engine rotation stop position is calculated based on the signal from the motor rotation position sensor 44 that is stopped (steps 107 and 108).

  In the second embodiment described above, the engine rotational speed NE and the engine rotational direction are detected based on the signal of the motor rotational position sensor 44 with the camshaft phase controlled to the most retarded position or the most advanced position. Therefore, the movable portion of the variable valve timing device 18 is pressed against the retard side or the advance side stopper portion to fix the camshaft phase at the most retarded position or the most advanced position, and the rotational speed of the drive motor 26. The engine rotational speed NE and the engine rotational direction can be detected based on the motor rotational position signal in a state where the rotational speed of the intake camshaft 16 is forcibly matched, and the detection accuracy of the engine rotational speed NE and the engine rotational direction is detected. Can be further improved.

  Further, when the engine 11 is stopped with the camshaft phase controlled to the most retarded position or the most advanced position, the engine rotation stop position is detected based on the signal of the motor rotation position sensor 44. Therefore, the engine rotation stop position is detected based on the signal of the motor rotation position 44 when the engine 11 is stopped while the rotation position relationship between the rotation shaft 27 of the drive motor 26 and the cam shaft is forcibly fixed. This can further improve the detection accuracy of the engine rotation stop position.

In the first and second embodiments, the engine rotation speed NE is detected based on the signal from the motor rotation position sensor 44 when the engine rotation speed NE is lower than a predetermined value. The engine rotational speed NE may be detected based on a signal from the motor rotational position sensor 44.
Further, the motor rotational position sensor 44 may be substituted when the crank angle sensor 20 fails.

  Further, the present invention is not limited to the variable valve timing device 18 for the intake valve, but may be applied to a variable valve timing 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. A motor-driven variable in which the camshaft phase is maintained by rotating the rotating shaft in synchronization with the camshaft, and the camshaft phase changes by changing the rotational speed of the drive motor relative to the rotational speed of the camshaft. Any valve timing device 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 longitudinal cross-sectional view of a drive motor. It is a flowchart which shows the flow of a process of the engine rotation state detection program of Example 1. FIG. It is a flowchart which shows the flow of a process of the engine rotation state detection program of Example 2.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 12 ... Crankshaft, 16 ... Intake side camshaft, 18 ... Variable valve timing device, 20 ... Crank angle sensor, 21 ... Phase variable mechanism, 22 ... Outer gear, 23 ... Inner gear, 24 ... Planet Gear, 26 ... Drive motor, 27 ... Rotating shaft, 32 ... Stator, 36 ... Rotor, 41 ... Permanent magnet, 44 ... Motor rotation position sensor, 45 ... Sensor magnet, 46 ... Hall element, 48 ... ECU (Stop position detecting means) )

Claims (2)

A variable valve timing device is provided that changes the valve timing of an intake valve or an exhaust valve that is driven to open and close by the camshaft by changing the rotational phase of the camshaft relative to the crankshaft of the internal combustion engine (hereinafter referred to as "camshaft phase"). In the internal combustion engine rotation state detection device,
Said variable valve timing device, the camshaft phase by the rotation shaft of the driving motor during non-driving of the driving motor as a driving source is rotated in synchronization with the cam shaft is maintained current, drives the drive motor The cam shaft phase is changed by changing the rotation speed of the drive motor with respect to the rotation speed of the cam shaft,
A motor rotation position sensor that outputs a motor rotation position signal corresponding to the rotation position of the drive motor;
Stop position detecting means for detecting the rotation stop position of the internal combustion engine based on the motor rotation position signal output from the motor rotation position sensor when the drive motor is not driven while the internal combustion engine is stopped. An internal combustion engine rotation state detection device.   The stop position detecting means stops the rotation of the internal combustion engine based on the motor rotation position signal when the internal combustion engine is stopped with the camshaft phase controlled to the most retarded position or the most advanced position. 2. The rotational state detection device for an internal combustion engine according to claim 1, wherein the position is detected.

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