JP5948421B2 - Automatic engine stop / restart device - Google Patents

Description

  The present invention relates to an automatic engine stop / restart device.

  In the idle stop system, when the engine is automatically stopped, the engine stop operation is started based on the determination on the system side, not based on the direct operation of the driver. For this reason, a driver | operator's condition may change during an automatic stop, and it may be necessary to operate an engine immediately. The idle stop system is required to restart the engine without feeling a delay in response to the driver's restart request. The most severe condition for satisfying this requirement is when an engine restart request is generated immediately after the automatic stop operation is started. In a system that restarts using a conventional pinion jump-in starter, it is necessary to wait for the engine to come to a complete standstill in order to engage the pinion of the starter with the ring gear of the engine. This is because if the starter is jumped in before the motor is completely stopped and the motor is energized, a very large noise is generated when the biting fails, and the starter and the ring gear are damaged. However, waiting for the engine to come to a complete standstill takes time to restart, and the driver feels dissatisfied. Therefore, in recent years, techniques for restarting the engine by the starter have been developed by various methods even before the engine is completely stopped.

  As an example of the technology developed in recent years, there is JP 2011-144799 A (Patent Document 1). In this publication, when a restart request is generated during the engine rotation descent period immediately after starting the operation to automatically stop the engine, a pinion of the starter is pushed out to a ring gear directly connected to the crankshaft of the engine. A technique for biting and restarting the engine with a starter is described. Japanese Patent Application Laid-Open No. H10-228561 describes that as an operation at that time, the timing for turning on the contact of the starter motor is delayed by a certain time with respect to the operation timing of the means for pushing the pinion. This ensures that the starter pinion and the engine ring gear are engaged with each other in a situation where the rotational speed is changing while the engine rotation is not yet completely stopped. It has been.

  Japanese Patent Laid-Open No. 2012-41859 (Patent Document 2) measures the rotational behavior of the engine after extruding the starter pinion, and whether the pinion and the ring gear are engaged based on the reverse rotation amount of the engine rotation. Techniques for determining the are described. As a result, when the pinion has failed to be bitten, it is possible to recognize this, and it is possible to restart the engine with an operation procedure suitable for each state.

  Furthermore, Japanese Patent Application Laid-Open No. 2012-62760 (Patent Document 3) includes a means for predicting a trajectory of a decrease in engine rotation speed. Based on the predicted trajectory, the starter motor is driven first and then the pinion is turned on. A technique for selecting whether to drive the motor after extruding or pinion is described. Thereby, it is possible to further increase the probability that the engagement between the pinion and the ring gear is successful.

JP 2011-144799 A JP 2012-41859 A JP 2012-62760 A

  When restarting the engine using the starter before the engine is completely stopped, as in the method of Patent Document 1, when a certain interval is to be provided between the pinion extrusion and the motor energization, the time The interval must be set according to the case where it takes time to engage the pinion and the ring gear, and in the time setting that can cover the worst case, the generation of noise during that time is allowed, and sufficient silence is achieved. I can't plan.

  The above problem must be matched to the worst case because the system cannot know whether the starter pinion and the ring gear are engaged. For this reason, it can be said that the technique of determining whether or not the engagement of the pinion and the ring gear is successful by the technique of Patent Document 2 is one of the effective means. However, in the technique of Patent Document 2, since it is known whether or not the meshing is successful at the time when the reverse rotation operation of the engine rotation is completed, it cannot be determined at the previous time, and before the reverse rotation operation is completed. It cannot be used for cases where it is desired to restart the system.

  On the other hand, the method of Patent Document 3 predicts the engine rotation trajectory and uses two types of operation procedures accordingly, increasing the probability of successful engagement of the pinion and the ring gear, which causes noise generated during engagement. It also helps to reduce However, it is difficult to accurately predict the rotation trajectory of the engine, and the rotational behavior varies depending on the state of the engine at that time, so the actual engine rotation is lower than the predicted trajectory. It can happen. At that time, if the starter motor is turned on in accordance with the prediction and the starter is rotated first to engage the pinion, the actual engine rotation speed may be lower than the starter rotation speed. Yeah. In that case, since the motor of the starter is ON, the rotational speed continues to increase, and the rotational speed of the engine is decelerated from the predicted trajectory. In this case, the rotational speed of the starter pinion and the rotational speed of the ring gear are different from each other, and it is difficult for the two to mesh. Such a situation must be avoided because the pinion and the ring gear have a relative rotational speed difference, and an abnormal noise is generated when the pinion and the ring gear are not engaged with each other. Therefore, even when the rotation of the engine is not completely stationary, a method for reducing the generation of noise by causing the pinion and the ring gear to be more reliably engaged is required.

  In order to solve the above problems, for example, the configuration described in the claims is adopted. The present application includes a plurality of means for solving the above-mentioned problems. As an example, the following means is adopted. That is, the engine is automatically stopped and restarted while the engine is running, and at the time of the restart, the starter pinion is pushed out, and the pinion is engaged with the ring gear directly connected to the crankshaft of the engine. However, in the automatic engine stop / restart device for controlling the engine to be restarted by the starter, the rotational speed of the engine is determined, and when the rotational speed is equal to or greater than a threshold value, the starter motor is energized. When the rotational speed is less than or equal to a threshold value, control is performed so that the motor is energized only when the pinion is engaged with the ring gear.

  By using the present invention, when the engine speed is predicted and the pinion is pushed out and engaged with the ring gear, even if the engine speed is lower than predicted, it is below the set threshold. If there is, the motor of the starter is energized only when the pinion is engaged, and the motor is energized when the pinion is not engaged, and the rotation speed of the pinion and the ring gear deviates so that the pinion is engaged. It becomes possible to avoid being lost. As a result, noise generated when the pinion is bitten can be reduced, and it is ensured that the engine can be restarted immediately when the engine needs to be restarted. This eliminates the problem of frequent idle stop operations, so it is possible to increase the frequency of idle stops and further increase the engine fuel consumption if the engine is stopped longer. It becomes possible to reduce.

1 is a configuration diagram of an automatic engine stop / restart device according to a first embodiment of the present invention. FIG. The block diagram of the automatic engine stop restart apparatus in 2nd Example in this invention. The block diagram of the automatic engine stop restart apparatus in the 3rd Example in this invention. The 1st example of the restart operation | movement in the structure of the 1st Example in this invention. The 2nd example of the restart operation | movement in the structure of the 1st Example in this invention. The 3rd example of the restart operation | movement in the structure of the 1st Example in this invention. The 4th example of the restart operation | movement in the structure of the 1st Example in this invention. The 5th example of the restart operation | movement in the structure of the 1st Example in this invention. The example of the restart operation | movement in the structure of the 2nd Example in this invention. The example of the restart operation | movement in the structure of the 3rd Example in this invention. A reference for the crank angle used when predicting the rotational speed of the engine in the present invention. The example of the function used when estimating the rotational speed of the engine in this invention.

  Embodiments will be described below with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of an automatic engine stop / restart device according to a first embodiment of the present invention. The starter 1 is attached to a cylinder block (not shown) of the engine and is connected to the battery 3 by wiring. When the motor 4 is energized, the rotational force is transmitted through the output shaft 5 to rotate the pinion 7 integrally formed with the one-way clutch 6. The ring gear 8 is directly connected to the crankshaft (not shown) of the engine, and the power of the motor 4 is transmitted when the ring gear 8 and the pinion 7 are engaged with each other. When the pinion 7 is meshed, either one or both of the electromagnetic coils 17 and 18 in the mag switch 11 are energized to generate a magnetic attractive force, thereby attracting the plunger 15 and via the shift lever 9. The movement is transmitted to the pinion and pushed forward. When the pinion 7 and the ring gear 8 are disengaged, the energization of the electromagnetic coils 17 and 18 is turned off, and the plunger 15 is returned to the original position by a spring (not shown) in the mag switch 11, and the shift lever 9 is moved. The movement is transmitted to the pinion through the original position. In the present embodiment, the pinion 7 is integrated with the one-way clutch 6, but another configuration is also possible. Further, a speed reducer for amplifying torque may be provided between the motor 4 and the output shaft 5.

  When the movement of the plunger 15 in the mag switch 11 is transmitted to the pinion 7 via the shift lever 9, the movement of the lever is used with the drive spring 10 as a fulcrum. That is, when the fulcrum by the drive spring 10 does not move, the pinion 7 is pushed to the right when the plunger 15 is pulled to the left, and the pinion 7 is pulled to the left when the plunger 15 is pushed to the right. When the pinion 7 is pushed right and meshed with the ring gear 8, the pinion 7 moves to the full stroke in the right direction, and the plunger 15 moves to the left in the full stroke. There is a movable contact 14 on the left side of the plunger 15, and when the plunger makes a full stroke movement in the left direction, the movable contact 14 is also pushed to the left, the fixed contacts 12 and 13 are connected, and the motor is energized. become. The movable contact 14 is applied with a force in the right direction by a spring (not shown). The fixed contacts 12 and 13 are connected only when the movable contact 14 is pushed by the plunger 15, and the contact is connected when the plunger 15 returns to the original position. Is released.

  When engaging the pinion and the ring gear, as a case where the engagement fails, if the end surfaces of the pinion 7 and the ring gear 8 collide and the gear teeth cannot be held between the teeth, the pinion 7 Further, it cannot move to the right, so that the plunger 15 cannot move to the left any more. At this time, when the deflection of the drive spring 10 occurs and the position of the fulcrum shifts to the left, the plunger 15 can move to the left even if the pinion 7 does not move. Since the deflection of the drive spring 10 is generated based on a force for moving the plunger 15 to the left, the deflection amount of the drive spring 10 can be adjusted by a magnetic attractive force with respect to the plunger 15. Therefore, when both the electromagnetic coils 17 and 18 are energized, the magnetic attractive force with respect to the plunger 15 becomes strong, the drive spring 10 bends much, and the amount of movement of the plunger 15 to the right also increases accordingly. When only one of the electromagnetic coils 17 and 18 is energized, the magnetic attraction force is weak accordingly, and the amount of movement of the plunger 15 due to the deflection of the drive spring 10 is also reduced.

  Only when both the electromagnetic coils 17 and 18 are energized, the movable contact 14 is moved by moving the plunger 15 so that the contact can be energized. When only one of the electromagnetic coils 17 and 18 is energized, If the contact is not energized because the movement is small, it is possible to select whether or not the motor 4 is energized in that state in the case where the pinion has failed to engage the ring gear. That is, if only one of the electromagnetic coils 17 and 18 is energized, the motor 4 is energized if the engagement is successful, and the motor 4 is not energized if the engagement fails. On the other hand, when both the electromagnetic coils 17 and 18 are energized, the motor 4 is energized regardless of the success or failure of the biting.

  The operation as described above is made possible by the design of the magnetic attractive force of the mag switch 11, the spring constant of the drive spring 10, and the stroke of the movable contact 14.

  Switching of energization to the electromagnetic coil 17 is performed by a relay switch 19. Similarly, switching of energization to the electromagnetic coil 18 is performed by a relay switch 20. When the energization is cut off by the relay switches 19 and 20 from the state where the electromagnetic coil is energized, a surge voltage may be generated due to the current interruption, and the relay switch may be damaged. Therefore, the diodes 23 and 24 are installed. However, it is possible to take measures against this. That is, when the electromagnetic coils 17 and 18 are energized, a magnetic field is formed around the coil. When the current is cut off and the current flowing through the coil is reduced, the magnetic field is also reduced. An induced electromotive force is generated in a direction that cancels the change. Therefore, the more rapidly the current decreases, the greater the induced electromotive force. Therefore, a surge voltage is generated when power is turned off. If the diode 21 connected to the ground is provided, even if the electromagnetic coil 17 is de-energized, the induced electromotive force that is generated causes a current to flow through the diode 23, and the change in the current of the electromagnetic coil 17 is reduced. Can be prevented. Similarly, when the diode 24 is provided, it is possible to prevent the electromagnetic coil 18 from generating a surge voltage.

  The controller 34 controls all the operations of the starter 1 by directly controlling the relay switches 19 and 20. Further, when the control is performed, the operation is determined by receiving a signal from the engine rotation speed detector 42, information on the crank angle, and information on a restart request.

  FIG. 2 is a diagram showing a configuration of an automatic engine stop / restart device according to the second embodiment of the present invention. Explaining only the difference from the first embodiment, the energization of the electromagnetic coils 17 and 18 is controlled by the semiconductor switch 22. The semiconductor switch 22 also controls the energization of the motor 4. Unlike a mechanical switch, a semiconductor switch can be switched ON / OFF by only the action of a semiconductor. Therefore, the time required for switching ON / OFF is very short and can be switched frequently. Therefore, PWM control can be performed, and the current flowing through the electromagnetic coils 17 and 18 can be controlled by changing the ON / OFF time ratio (= duty). In addition, by providing the diode 25 inside the semiconductor switch 22, it becomes possible to continue to flow the current due to the induced electromotive force to the electromagnetic coil or the motor side even when the semiconductor switch is turned off, and the generation of the surge voltage. Is prevented.

  Since the semiconductor switch is insulated or energized with electrical characteristics, it may remain energized if the characteristics are broken. In order not to cause a serious problem even if such a failure occurs, a mechanical relay switch 21 is provided in series with the semiconductor switch 22, the re-lace switch 21 is turned ON only during normal operation, and otherwise If the relace stitch 21 is turned off, the safety of the system is ensured.

  The control device 34 controls only the semiconductor switch 22 and the re-lace switch 21. When the magnetic attractive force of the mag switch 11 is increased, the duty of the semiconductor switch 19 is increased, and when the magnetic attractive force is decreased, the duty of the semiconductor switch 19 is increased. Lower. That is, when the duty of the semiconductor switch 19 is increased, the time ratio of turning on increases and the current increases, thereby increasing the magnetic attractive force. When the duty is decreased, the time ratio of turning on decreases and the current decreases. As a result, the magnetic attractive force decreases.

  Therefore, when the motor 4 is energized even when the pinion 7 is not engaged with the ring gear 8, the duty of the semiconductor switch 22 is increased, and the pinion 7 is not engaged with the ring gear 8. When operating so that the motor 4 is not energized, the duty of the semiconductor switch 22 is lowered.

  Further, when the motor 4 is energized, the current flows through the semiconductor switch 22. Therefore, the current flowing through the motor 4 can be controlled by adjusting the duty of the semiconductor switch 22. In order to restart the engine by the power of the motor 4, a large torque is required, so that a current flowing through the motor 4 is also large. The battery 3 causes a voltage drop when a large current flows. Some devices (not shown) connected to the battery 3 cannot operate normally when the voltage drops, and the battery voltage drop may cause a problem even if it is temporary. If the current flowing through the motor 4 can be suppressed by the semiconductor switch 22, it is possible to suppress the voltage drop of the battery. As a means for suppressing the current flowing through the motor 4, there is a method of adding an electric resistance. However, it is not preferable to pass a current through the resistor because energy is lost and heat is generated. When PWM control is performed by the semiconductor switch 22, current can be suppressed without energy loss, and energy efficiency can be increased, so that fuel consumption of the engine can be further reduced.

  FIG. 3 is a diagram showing the configuration of an automatic engine stop / restart device according to the third embodiment of the present invention. Explaining only the difference from the first and second embodiments, the current control circuit 26 controls the energization of the electromagnetic coils 17 and 18. A principle circuit diagram of the current control circuit 26 is shown on the lower side of the figure. In this circuit, the operational amplifier 29 detects the voltage generated according to the current flowing through the shunt resistor 27. The voltage detected here is information corresponding to the current to be controlled, and the difference between this information and the target current is taken by the operational amplifier 30 and given to the transistor 28 so that the target current is automatically reached. Circuit configuration. The target current at this time is determined by the controller 34 and is transmitted to the current control circuit 26 by a voltage signal. Although it is the same as that of the second embodiment in that energization is controlled by a transistor, when PWM control is performed as in the second embodiment, when it is performed by open control, a change in resistance value on the load side or a power supply voltage When a change occurs, correction according to the change cannot be performed. On the other hand, when the current control circuit is used, even if the resistance value of the electromagnetic coil changes with temperature or the battery voltage changes, the current flowing at that time is detected and feedback is applied, so the current will be the target value. Automatically controlled. When the currents flowing through the electromagnetic coils 17 and 18 are controlled according to the target values, it is possible to reduce the variation in the magnetic attractive force generated by the currents, which is determined by the balance between the magnetic attractive force and the spring force of the drive spring 10. It becomes possible to stabilize the operation.

  FIG. 4 shows a first example in which the engine is restarted with the configuration of the first embodiment of the present invention. The upper side of the figure is the timing of various operations, and the lower side is a graph showing the time change of the engine speed. The upper and lower figures show the same time. The situation shows the operation after the engine system has decided to stop idling. After the fuel injection is stopped by the idle stop, the engine speed gradually decreases while pulsating. The restart request state shown at the top of the timing diagram is switched from OFF to ON at time t1, indicating that a restart request has occurred at time t1. After time t1 when the restart request is generated, fuel is injected on the combustion control side, and it is prepared to resume combustion. However, since the timing at which the engine can perform fuel injection and combustion is determined, the engine speed continues to decrease until that time. Meanwhile, on the side of the system that controls the starter, the control device 34 continues to predict subsequent changes in the engine speed, and turns on the relay switch 19 at time t2. This switch operation energizes the mag switch 11 by half, generates a magnetic attractive force, and pushes out the pinion 7. The engine speed is predicted in advance when the pinion and the ring gear come into contact with each other by pushing out the pinion 7, and the control device 34 takes the timing and turns on the relay switch 19 so that the speed reaches the target value. Determine the timing. Even after the pinion and the ring gear come into contact, when the engine speed is higher than a predetermined value, the relay switch 20 is turned on so that the magnet switch 11 is fully energized. Thereby, even if the pinion is not biting into the ring gear, the drive spring 10 is deflected, the plunger 15 pushes the movable contact 14, and the motor 4 is energized. The starter pinion rotation number is converted into the synchronized engine rotation number and expressed as "starter rotation number", and the motor contact is turned on after time t3, the starter starts to rotate, The rotational speed gradually increases. At time t4 when the rotation speed of the starter pinion and the rotation speed of the ring gear of the engine approach each other, the gears can naturally engage with each other, and at the same time the pinion is engaged, the engine is driven by the starter (= Cranking) starts and the engine speed starts to increase. Thereafter, when engine combustion starts, the engine speed further increases and becomes higher than the starter speed, and the restart of the engine is completed. In addition, what was shown with the broken line in the graph of an engine speed shows the behavior of the engine when the pinion is not bitten in reference.

  In this case, after starting the push-out of the pinion at time t2, the engine speed started to rise again in the behavior where the engine speed pulsated, so that the speed of the starter and the pinion was away. However, when this is detected and the relay switch 20 is turned on immediately, the rotation of the starter starts and the pinion and the ring gear can be meshed without waiting for the engine speed to drop. This contributes to shortening the time required for starting.

  In order to realize this movement, it is important to appropriately determine that the relay switch 20 is turned on, and at the same time, the control device 34 captures the information of the sensor for detecting the rotation speed of the engine for that purpose. Information on the crank angle is also used, and the engine speed is always predicted from the latest information, and the operation of the relay switch 20 is determined by comparing it with a predetermined threshold value. In addition to the present embodiment, the relay switches 19 and 20 can be operated by switching them.

  FIG. 5 shows a second example in which the engine is restarted with the configuration of the first embodiment of the present invention. In this embodiment, the restart request is generated at a later timing than the previous example. For this reason, the engine speed is close to 0 at time t1 when the restart request is generated. For this reason, the control device 34 turns on the relay switch 19 simultaneously with the restart request. As a result, the pinion is pushed out. However, in this case, the engine speed is low (negative), so the relay switch 20 remains OFF all the time. Even when the relay switch 20 is OFF, the absolute value of the engine rotational speed is low, and the relative rotational speed with the pinion is small, so that the pinion can naturally mesh with the ring gear. As a result, when the pinion bites and moves forward, the plunger of the mag switch that moves by the link mechanism advances to the back, and the contact of the motor is naturally turned on even if the drive spring 10 is not bent. The pinion bites at time t2 and the motor contact is energized at the same time, whereby cranking of the engine starts, and the rotation of the engine and the starter increases synchronously. Thereafter, when the combustion starts, the engine speed increases to the starter speed or higher, and the restart is completed. Also in this figure, the engine speed indicated by a broken line is a reference of the behavior of the engine when the pinion is engaged with the ring gear.

  In this operation, since the relay switch 20 is kept OFF, the motor is not energized before the pinion meshes with the ring gear. If the motor is energized before the pinion meshes with the ring gear in this situation, the rotation speed of the pinion increases while the engine rotation is in the reverse rotation phase. Therefore, it will accelerate in the negative direction. If this happens, the relative rotational speed difference between the pinion and the ring gear increases, and the pinion cannot be bitten. When the pinion and ring gear have a relative speed difference, if the end faces of the gear are kept pressed against each other, abnormal noise is generated and gear wear increases, so this is an operation that should be avoided. Avoiding this is realized by keeping the relay switch 20 OFF. At the same time, since the relay switch 19 is turned on, it is quickly restarted by the natural meshing of the gears.

  FIG. 6 shows a third example in which the engine is restarted with the configuration of the first embodiment of the present invention. In the present embodiment, the restart request for the engine speed and the timing for turning on the relay switch 19 are the same as the example shown in FIG. However, the case where the pinion and the ring gear are not immediately engaged is shown. The reason why it takes time to bite is that the engine speed is large and negative. If the relative rotational speed difference is large, the gears are difficult to bite. Even if the engine rotational speed temporarily becomes a large negative value, it will eventually return to 0, so that the pinion naturally bites into the ring gear at the time t2 when the absolute value in the negative rotation becomes small. As a result, the motor contacts are turned on, cranking starts, and restarting is performed.

  FIG. 7 shows a fourth example in which the engine is restarted with the configuration of the first embodiment of the present invention. The present embodiment shows a case where a restart request is made at the same timing as the embodiment of FIGS. 5 and 6, and as a difference, shows a case where the pinion does not naturally bite into the ring gear. . In order to make the pinion engage with the ring gear, it is necessary not only to press the pinion but also to rotate them relative to each other. Therefore, programming is performed so that the relay switch 20 is turned on after a certain period of time has elapsed after the engine rotation speed becomes equal to or less than a certain value. As a result, it is possible to avoid that the engine rotation is stationary and the starter does not rotate, so that they cannot be engaged with each other.

  FIG. 8 shows a fifth example in which the engine is restarted with the configuration of the first embodiment of the present invention. This operation example is common to the embodiment of FIG. 4 in that a restart request is generated when the engine speed is still high. After the restart request is generated at time t1, the control device 34 continues to predict the engine speed, and turns on the relay switch 19 at time t2, which is an appropriate timing. At this time, the relay switch 20 is also turned on at the same time, and after a short time, the relay switch 20 is turned off. Since the mag switch 11 energized by the relay switches 19 and 20 needs to generate a magnetic attractive force sufficient to push out the pinion 7, a large amount of magnetic flux is generated. When a magnetic flux is generated, a counter electromotive force is generated, so that a full current does not immediately occur, and a certain time is required to reach a steady magnetic attractive force. For this reason, when both the relay switches 19 and 20 are turned on only for a short time, the magnetic attraction force rises quickly, and the start of movement of the pinion can be accelerated. Since the relay switch 20 is energized only for the purpose of speeding up the movement of the pinion, the relay switch 20 is turned off at the timing when the pinion starts to move. Also, if the movement speed of the pinion is too fast, the bounce after colliding with the end face of the ring gear becomes large and it becomes difficult to bite, so the relay switch 19 is turned off for a short time before colliding with the ring gear. . This prevents the pinion from moving too fast and presses the pinion against the ring gear. When the pinion comes into contact with the ring gear and the engine speed is appropriate, it is possible to quickly engage, and the motor is energized at time t3 due to the engagement of the pinion. As a result, cranking is performed and the engine is restarted.

  FIG. 9 shows an example of restarting the engine with the configuration of the second embodiment of the present invention. Since the behavior of the engine and the timing of the restart request are the same as in the example of FIG. 8, the time t2, which is the timing for starting energization of the mag switch, is also the same. However, since the hardware configuration is changed from the relay switch to the semiconductor switch, the operation at time t2 increases the duty of the semiconductor switch from 0 to 100%. The semiconductor switch is completely energized when the duty is 0%, and fully energized when the duty is 100%. Immediately after time t2, full energization is performed to make the pinion start to move faster, but thereafter the duty is once reduced to prevent the pinion moving speed from being increased too much. When the pinion contacts the ring gear, it is programmed to have an intermediate duty. Thereafter, energization of the motor starts when the pinion is bitten at time t3. At this time, the current flowing through the motor is also reduced by the duty set in the semiconductor switch. A DC motor used in a starter generates a large torque when a motor has a low rotational speed and generates a large torque. Generating a large torque is advantageous in terms of shortening the restart time. However, if a large amount of current is consumed, the resulting voltage drop of the battery is large, and other devices sharing the battery are affected. Therefore, when restarting the starter, it is better to reduce the flowing current to some extent, and it is convenient to reduce the current by the semiconductor switch. After that, when the engine starts to rotate, the starter also increases, so the current that flows to the starter starts to decrease.After that, gradually increase the duty of the semiconductor switch to an appropriate current, thereby increasing the torque of the starter. To shorten the restart time.

  FIG. 10 shows an example of restarting the engine with the configuration of the third embodiment of the present invention. Since the engine behavior and the restart request timing are the same as those in the examples of FIGS. 8 and 9, the timing t2 at which energization of the mag switch is started is also the same. In the configuration of the present embodiment, in order to instruct the current control circuit of the target value of the current to be passed through the mag switch, a full energization instruction is issued at time t2. Thereafter, in order to prevent the movement speed of the pinion from increasing too much, the target value of the current is once lowered, and programming is performed so that the target value becomes an intermediate value when the pinion contacts the ring gear. Thereafter, when the pinion is bitten at time t3, the motor begins to be energized and the engine is restarted.

  A method for predicting the behavior of the engine rotation in order to determine the timing for starting energization of the mug switch will be described with reference to FIGS. 11 and 12. In the prediction, information on the measured engine speed and information on the crank angle are used. Based on both pieces of information, the function shown in FIG. 12 is used for prediction. At that time, the crank angle used is determined as shown in FIG. In this description, a three-cylinder engine will be described as an example, but the idea is the same for other cylinders.

  In FIG. 11, when the first cylinder starts from the compression process, the subsequent steps are the expansion process, the exhaust process, and the intake process, and the entire process is repeated from the original state. At the moment when the compression process is completed and the expansion process starts, the piston of the engine has reached top dead center, which is shown as TDC in the figure. In a four-cycle engine, the crank angle is one rotation and one cycle, so a crank angle of 720 ° is one cycle. In the three-cylinder engine, the phase is shifted by an angle obtained by dividing the angle into three equal parts, that is, 240 °. Accordingly, the TDC of the first cylinder, the TDC of the second cylinder, and the TDC of the third cylinder are out of phase by 240 °. In each cylinder, the piston comes to the top dead center as well as the timing of the TDC shown in the figure, but also at the moment when the exhaust process is completed. Here, attention is paid to the TDC at the end of the compression process. When combustion is not performed, the pressure in the cylinder is highest at the TDC instant at the end of the compression process, and the pressure in the cylinder acts as a force to push the piston through before and after that, and governs the rotational behavior of the engine. Therefore, the TDC at the end of the compression process is used as a reference for the crank angle, the crank angle at the TDC is set to 0 °, and the crank angle is expressed by 120 ° before and after. Therefore, after the state where the first cylinder defines the expression of the crank angle has passed, the crank angle is defined with reference to the TDC of the second cylinder, and then circulates as defined by the third cylinder. .

  A function for predicting the behavior of the engine rotation using the crank angle defined in FIG. 11 is as shown in FIG. In the graph shown at the top of FIG. 12, the horizontal axis represents the crank angle, and the vertical axis represents the engine acceleration (= rate of change in rotational speed). In a state where the engine is not combusting, it is assumed that the engine performs the behavior according to the acceleration shown here, and the rotational behavior of the engine is predicted. That is, it is considered that the behavior while the engine is stopped is behavior according to the function of Expression (1). The specific contents of equation (1) are shown in equation (2), and the acceleration of the engine is mainly defined by the crank angle, which is shown in the graph at the top. . In a three-cylinder engine, the same state is repeated every time the crank angle is 240 °, so the function is described using a Fourier series with 240 ° as one cycle. A function other than the Fourier series may be used. The coefficients a1 to a4 and b1 to b4 are constants, and the coefficient a0, which is a steady component, varies depending on the engine speed as shown in Expression (3). In equation (3), the coefficients c and k are positive number constants. That is, when the engine rotation is normal, the steady component of acceleration is negative, and when the engine is reverse rotating, the steady component of acceleration is positive. In the expression (3), the forward rotation and the reverse rotation are connected by a linear function, but it can also be defined by a function having a hysteresis. Also, the coefficients a1 to a4 and b1 to b4 in the equation (2) can be changed depending on the engine speed. The engine speed Ne [rpm] and the crank angle θ [°] are linked by the relationship of the equation (4).

  When the engine speed Ne and the crank angle θ at the time t are known from the information input to the control device, a method for obtaining the engine speed and the crank angle after the time Δt is a function of equations (5) and (6). It becomes. Equation (5) is obtained by integrating the equation (1) with time, and equation (6) is obtained by integrating the equation (4) with time. If the stop behavior of the engine is measured in advance and the coefficients of equations (2) and (3) are determined, equations (5) and (6) can be integrated numerically, and the engine behavior is predicted by the integral calculation. It becomes possible to do. Performing this integral calculation in real-time control is computationally expensive and requires an expensive computer. Therefore, if integral calculation is performed in advance and the results are tabulated, real-time control is performed. Sometimes, referring to the table, a calculation result equivalent to the above integral calculation can be obtained by interpolation calculation of the table. Since this calculation can be solved by giving the engine speed Ne and the crank angle θ to the initial conditions, the calculation using the engine speed Ne, the crank angle θ, and the prediction time Δt as parameters is performed in advance, and the calculation result for them If the control device holds the table as a table, the engine speed behavior can be easily predicted.

DESCRIPTION OF SYMBOLS 1 Starter 3 Battery 4 Motor 5 Output shaft 6 One-way clutch 7 Pinion 8 Ring gear 9 Shift lever 10 Drive spring 11 Mag switch 12, 13 Fixed contact 14 Movable contact 15 Plunger 17, 18 Electromagnetic coil 19, 20, 21 Relay switch 22 Semiconductor Switch 23, 24, 25 Diode 26 Current control circuit 27 Shunt resistor 28 Current control transistor 29, 30 Operational amplifier 34 Controller 42 Engine rotation speed detector

Claims (3)

During engine operation, the engine is automatically stopped and restarted,
In the automatic engine stop / restart device for controlling the restarting of the engine by the starter by pushing out the pinion of the starter at the time of restarting, causing the pinion to engage with the ring gear directly connected to the crankshaft of the engine ,
The rotational speed of the engine is determined, and when the rotational speed is equal to or greater than a threshold value, a control for energizing the starter motor is performed
Wherein when the rotation speed is less than the threshold value, when said pinion is bitten to the ring gear only, have lines control for energizing the motor,
The starter is configured to serve both as a mechanism for pushing out the pinion and a mechanism for controlling energization of the motor,
The mechanism is capable of both control to energize the motor when the pinion is not engaged with the ring gear and control not to energize the motor until the pinion is engaged with the ring gear.
The mechanism operates by moving the movable iron core by the magnetic attraction force of the electromagnetic coil. When the magnetic attraction force is controlled to be weaker than a predetermined value, the motor is energized until the pinion is pushed out a predetermined distance. First, when the magnetic attraction force is controlled to be stronger than a predetermined value, the motor is energized before the pinion is pushed out for the predetermined distance . The automatic engine stop / restart device according to claim 1 ,
The electromagnetic coil is composed of a plurality of coils,
An automatic engine stop / restart device that changes a magnetic attractive force by changing the number of coils to be energized among the plurality of coils. The automatic engine stop / restart device according to claim 1,
In determining the rotational speed, the information related to the engine crank angle and the information related to the engine rotational speed are used, and the information related to the engine rotational speed and the information related to the engine crank angle are combined and pushed out. An automatic engine stop / restart device that estimates an engine rotation speed when the pinion contacts the ring gear and controls the starter based on the engine rotation speed.

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