JP2017002820A - Engine start control device and engine start control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress slip of a belt by performing optimal engine start control with a motor generator and a starter, improve durability of the belt and optimize output performance of the motor generator and starter, and thereby attain improve durability and attain downsizing.SOLUTION: An engine start control device includes: a first electric motor that is always connected to an engine by a belt, and performs cranking by generating driving torque in engine start; a second electric motor that is connected to the engine by a gear in engine start, and performs cranking by generating auxiliary torque; and a start controller that cranks the engine by using the first electric motor and the second electric motor. The start controller, when the relative rotational speed difference between a rotational speed of the engine derived during cranking with both electric motors and a rotational speed of the first electric motor is equal to or more than a determination value, adjusts driving torque of the first electric motor so as to decrease it.SELECTED DRAWING: Figure 1

Description

  The present invention relates to engine start control of a vehicle equipped with a motor generator having a power generation function and a motor function at engine start, and a starter that assists the motor generator at engine start and cranks the engine. TECHNICAL FIELD The present invention relates to an engine start control device and an engine start control method for reducing the load of each motor generator and starter by optimally using a motor generator and a starter at the time of engine start, and reducing the cost of the motor generator, the motor generator inverter, and the starter. It is.

  A motor generator having a power generation function and an engine start function and a starter that cranks the engine when the engine is started are installed, and the engine is automatically stopped according to a set condition, and the engine is restarted by a restart request. A vehicle equipped with an idling stop function has been well known.

  In this type of vehicle, a motor generator linked to the engine is used to convert engine output into generated power, and the motor generator and starter are used separately or in combination depending on the situation, and the engine is started. (For example, refer to Patent Document 1).

  That is, during normal operation, the battery is charged from the motor generator by the rotational output of the engine, and when the engine is started, drive torque is supplied to the motor generator and the starter by battery power.

  For example, in the engine start control device described in Patent Document 1, based on at least one of information related to engine temperature and information related to auxiliary equipment, and information such as torque necessary for cranking the engine, It is specified that the engine is started by selecting one of cranking by a motor generator, cranking by a starter, and cranking by both a motor generator and a starter.

  Further, in the engine start control device described in Patent Document 1, the slip state of the belt (hereinafter referred to as belt slip) is determined after engine cranking starts, and the start control device detects the belt after engine cranking starts. A control method for selecting one of the cranking by the motor generator and the cranking by the starter based on the slip of the engine and cranking the engine until the start is completed is specified.

JP 2014-134130 A

However, the prior art has the following problems.
In the conventional engine start control device, the engine is started by a starter under a predetermined condition, and is restarted by a motor generator under another predetermined condition. Further, under predetermined conditions other than these, the engine is started by both the motor generator and the starter.

  When starting the engine by the control as described above, the starter is stopped when there is no slip of the belt. For this reason, for example, when the starter is stopped in a low rotation region where the friction torque of the engine is large, there is a concern that the belt may slip again as the starter stops. If the belt is slipping, the engine must be started only with the starter. That is, a rotational performance having a driving torque and a rotational speed equivalent to those of a starter mounted on a vehicle of a type not equipped with a motor generator is required. As a result, functions and sizes equivalent to those mounted on a vehicle of a type not equipped with a motor generator are required, and there is a problem that the engine start control device becomes large in combination with the motor generator.

  The present invention has been made to solve the above-described problems, and by performing optimal engine start control using a motor generator and a starter in combination, belt slippage is suppressed and belt durability is improved. An object of the present invention is to obtain an engine start control device and an engine start control method capable of optimizing the output performance of the motor generator and the starter and improving durability and downsizing.

  An engine start control device according to the present invention includes a first electric motor that is always connected to an engine by a belt and generates a driving torque at the time of starting the engine to perform cranking, and is connected to the engine by a gear at the time of starting the engine. A second motor that performs cranking by generating an engine, a start controller that uses both the first motor and the second motor to crank the engine at the time of engine start, and an engine speed detection that detects the engine speed And an engine start control device having a first motor rotation speed detector for detecting the rotation speed of the first motor, wherein the start controller is an engine detected by the engine rotation speed detector during combined cranking. The relative rotational speed difference between the rotational speed of the motor and the rotational speed of the first motor detected by the first motor rotational speed detector is derived. , The relative rotational speed difference is the greater than the first determination rotation speed difference is used to adjust the direction of lowering the driving torque of the first electric motor.

  In addition, the engine start control method according to the present invention includes a first electric motor that is always connected to the engine by a belt and generates a driving torque when starting the engine to perform cranking, and is connected to the engine by a gear when starting the engine. A second electric motor that cranks by generating auxiliary torque, a start controller that uses the first electric motor and the second electric motor together to crank the engine when the engine is started, and an engine rotation that detects the rotational speed of the engine An engine start control method executed by an engine start control device having a speed detector and a first motor rotation speed detector for detecting a rotation speed of a first motor, wherein the engine controls the engine with respect to the engine. A first step for determining whether or not a start request has occurred, and an engine start request is generated by the first step. Is determined by the engine speed detector after the combined cranking is started by the second step, and the combined cranking of the engine is started by the second step. The third step of deriving the relative rotational speed difference between the rotational speed of the engine and the rotational speed of the first motor detected by the first motor rotational speed detector, and the relative rotational speed difference derived in the third step are And a fourth step of adjusting the driving torque of the first electric motor to be lowered when the difference is larger than the first determination rotational speed difference.

  According to the present invention, the belt slip is detected by comparing the rotational speeds of the engine and the motor generator (first electric motor) during combined cranking. It is determined that the first electric motor) generates a driving torque exceeding the transmission capability of the belt, and the belt slip can be reduced by reducing the driving torque. As a result, optimal engine start control using both the motor generator and starter controls belt slippage, improves belt durability, and optimizes motor generator and starter output performance. An engine start control device and an engine start control method capable of realizing improvement and downsizing can be obtained.

It is a block diagram which shows schematic structure of the vehicle carrying the engine start control apparatus which concerns on Embodiment 1 of this invention. It is a flowchart which shows the flow of combined start control performed in the start controller by Embodiment 1 of this invention. It is a flowchart which shows the flow of combined starting control performed in the starting controller by Embodiment 2 of this invention. It is a flowchart which shows the flow of combined start control performed in the start controller by Embodiment 3 of this invention. It is a flowchart which shows the flow of combined start control performed in the start controller by Embodiment 4 of this invention.

  Hereinafter, preferred embodiments of an engine start control device and an engine start control method of the present invention will be described with reference to the drawings.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a schematic configuration of a vehicle equipped with an engine start control device according to Embodiment 1 of the present invention. In FIG. 1, the engine 1 is driven and controlled by an engine control device (hereinafter referred to as an engine ECU) 6 that controls the engine 1, which includes a function of determining whether to stop the engine at idling or to restart the engine.

  For example, a motor generator 2 as a first electric motor is always connected to the crankshaft 11 of the engine 1 via a belt 12. Further, for example, the pinion 31 serving as an auxiliary torque output portion of the starter 3 as the second electric motor transmits the auxiliary torque to the ring gear 13 integrated with the crankshaft 11. The starter 3 is attached to the ring gear 13 in a detachable state. In the following description, the drive torque output from the starter 3 will be referred to as auxiliary torque.

  An inverter 21 that functions as a power source for the motor generator 2 is connected to the motor generator 2. Further, the inverter 21 is connected to the battery 4 and a motor generator control circuit (hereinafter referred to as an MG control circuit) 22 that controls power generation and driving of the motor generator 2.

  The starter 3 includes an electromagnetic switch 32 having an electrical contact opening / closing function for supplying power to the starter 3. The electromagnetic switch 32 is connected to the battery 4.

  The MG control circuit 22 and the excitation terminal 32a of the electromagnetic switch 32 are respectively connected to the engine start control device 5 that performs control at the time of engine start. Hereinafter, the engine start control device 5 will be described as a start controller 5.

  The start controller 5 is connected to the engine ECU 6 and has a start control means for the engine 1. The start controller 5 can also be configured to be built in the engine ECU 6.

  Further, the engine 1 is provided with a crank angle sensor 14 for detecting the rotation angle of the crankshaft. The crank angle signal is transmitted to the engine EUC 6 and via the engine ECU 6 or directly, the start controller 5. Sent to.

  Here, as the engine rotation speed detector, for example, a method of deriving the rotation speed of the crankshaft of the engine 1 by calculating the output signal of the crank angle sensor 14 can be employed.

  Next, the function of the motor generator 2 will be described. The motor generator 2 has two functions: a generator function and a motor function. When functioning as a generator, the engine 1 is in an operating state, and is controlled by the MG control circuit 22 in a state in which the engine 1 is constantly rotating from the crankshaft 11 via the belt 12 by the driving torque of the engine 1. The generated power is rectified by the inverter 21 to charge the battery 4.

  Further, when functioning as a motor, it is a case where driving torque is supplied to the engine 1, and the power of the battery 4 is used and is supplied as power via an inverter 21 controlled by the MG control circuit 22 and is driven as a motor. Is done. Further, the driving torque is transmitted to the crankshaft 11 via the belt 12, and the engine 1 is driven.

  The motor generator 2 stops the function of the motor and starts the function of the generator after the start of the engine 1 is completed. In addition, when driving torque is supplied to the engine 1, there are two types, that is, when the engine 1 is started and when torque assist is performed to supplement the generated torque of the engine 1.

  Here, as the motor generator rotational speed detector that is the first electric motor rotational speed detector, for example, by calculating from information such as a current frequency for driving the motor generator 2 in the inverter 21, the rotational speed of the motor generator 2 is calculated. It is possible to adopt a method for deriving.

  Next, the function of the starter 3 will be described. The starter 3 is used when starting the engine. When a voltage is applied to the excitation terminal 32a of the electromagnetic switch 32, the electrical contact of the electromagnetic switch 32 is closed, and power is supplied to the motor unit of the starter 3, The pinion 31 moves to the ring gear 13 side. Then, when the ring gear 13 and the pinion 31 mesh with each other, auxiliary torque generated in the motor portion of the starter 3 is transmitted to the crankshaft 11 to drive the engine 1.

  The output shaft of the motor unit and the pinion moving body including the pinion 31 are related by a helical spline having an angle at which a propulsive force is generated from the stationary position to the ring gear 13 side when the motor unit is driven to rotate. Are combined.

  When the auxiliary torque of the starter 3 becomes unnecessary on the engine 1 side, the application of the voltage at the excitation terminal 32a is canceled. As a result, the state in which the pinion 31 is engaged with the ring gear 13 is eliminated, and the electrical contact of the electromagnetic switch 32 is opened, so that power is not supplied to the motor portion of the starter 3.

  The motor generator 2 functions as a motor driven by the MG control circuit 22 and the inverter 21 when the engine is started. The drive torque is transmitted from the motor generator 2 to the engine 1 by the belt 12. In this case, there is a concern that the belt 12 may slip when the temperature is low or the driving torque is large.

  Next, a series of operations by the start controller 5 in the first embodiment will be described. FIG. 2 is a flowchart showing the flow of the combined start control that is executed in the start controller 5 according to the first embodiment of the present invention.

  In step S110, the start controller 5 determines whether or not there is an engine start request for starting the engine 1 based on an operation state signal indicating the operation state of the engine and the vehicle input to the engine ECU 6. .

  If the result of determination in step S110 is that there is no engine start request (NO), the start controller 5 maintains the state and waits until there is an engine start request. On the other hand, if the result of determination in step S110 is that there is an engine start request (YES), processing proceeds to step S111.

  In step S111, the start controller 5 drives the electromagnetic switch 32 to close the electrical contact. As a result, when the motor circuit is energized, current is supplied to the motor unit of the starter 3, auxiliary torque is generated in the motor unit, and the starter 3 is started.

  Further, by driving the electromagnetic switch 32 to close the electrical contact, the pinion 31 moves to a position where it engages with the ring gear 13. As a result, the auxiliary torque of the motor unit is transmitted to the crankshaft 11 via the meshed pinion 31 and the ring gear 13, and the engine 1 is driven to rotate. Then, fuel injection is started.

  Further, in step S <b> 111, the start controller 5 supplies power to the motor generator 2 through the inverter 21 controlled by the MG control circuit 22 using the power of the battery 4. As a result, the motor generator 2 is driven as a motor and drives the engine 1 by transmitting driving torque to the crankshaft 11 via the belt 12.

  After starting the engine, the engine ECU 6 determines the rotational speed of the engine 1, that is, the rotational speed of the ring gear 13, based on the current crank angle and the cycle of the crank angle signal obtained from the crank angle signal from the crank angle sensor 14. Is calculated and monitored.

  The start controller 5 starts the combined cranking by the starter 3 and the motor generator 2 in step S111, and then monitors the current crank angle in step S112, and the rotational speed of the engine 1 near the top dead center is It is determined whether or not the rotation speed is equal to or higher than a predetermined rotation speed set for determination.

  Here, in the first embodiment, when the predetermined rotation speed is, for example, the rotation speed of the starter 3 when the crank angle of the engine 1 is top dead center, the start controller 5 determines in step S112. Then, it is determined whether or not the rotational speed of the engine 1 at the top dead center is equal to or higher than the rotational speed of the starter 3 at that time.

  At this time, the rotation speed of the engine 1 and the rotation speed of the starter 3 are compared with each other in consideration of the correlation between the rotation speed depending on the number of teeth of the ring gear 13 and the number of teeth of the pinion 31.

  If the result of determination in step S112 is that the rotational speed of the engine 1 at the top dead center is equal to or higher than the rotational speed of the starter 3 at that time (YES), the routine proceeds to step S113, where the start controller 5 The starter 3 is stopped. That is, the state in which the pinion 31 is engaged with the ring gear 13 is eliminated, and the electrical contact of the electromagnetic switch 32 is opened, so that the power supply to the motor unit of the starter 3 is stopped.

  After the starter 3 is stopped, in step S114, the start controller 5 determines whether or not the engine 1 has completely exploded, that is, whether or not the engine 1 has been started. If the result of determination in step S114 is that engine 1 has not been started (NO), start controller 5 maintains the state and waits until it is determined that engine 1 has been started.

  On the other hand, if the result of determination in step S114 is that the engine 1 has completely exploded (YES), the routine proceeds to step S115. In step S115, the start controller 5 stops the power supply to the motor generator 2 by the MG control circuit 22 and stops the function of the motor.

  On the other hand, as a result of the determination in the previous step S112, if the rotational speed of the engine 1 at the top dead center is not equal to or higher than the rotational speed of the starter 3 at that time (NO), the process proceeds to step S123 and the start controller 5 Determines whether or not the engine 1 has completely exploded, that is, whether or not the engine 1 has been started.

  If the result of determination in step S123 is that the engine 1 has not been started (NO), the process returns to step S112, and the start controller 5 determines the rotational speed of the engine 1 at top dead center and the starter 3 at that time. Are compared, and it is determined whether or not the rotational speed of the engine 1 at the top dead center is equal to or higher than the rotational speed of the starter 3 at that time.

  On the other hand, if the result of determination in step S123 is that the engine 1 has completely exploded (YES), the routine proceeds to step S124. In step S124, the start controller 5 stops the starter 3, further stops the power supply to the motor generator 2 by the MG control circuit 22, and stops the function of the motor.

  By these series of processes, the combined start control by the motor generator 2 and the starter 3 in the engine start is completed.

According to the start controller 5 configured as described above, the following features can be realized.
(Feature 1) If the rotational speed near the top dead center where the rotational speed of the engine 1 drops during combined cranking is equal to or higher than a predetermined rotational speed at which the auxiliary torque of the starter 3 is not effective, it can be determined that the starter 3 can be stopped. .

  In particular, by setting the predetermined rotation speed as the rotation speed of the starter 3 when the crank angle of the engine 1 is at the top dead center, it can be determined that the starter 3 is unnecessary for starting the engine at a time equal to or higher than the predetermined rotation speed. In other words. Since it can be determined that the cranking is performed only by the driving torque of the motor generator 2, the starter 3 can be stopped.

As a result, according to the first embodiment, the following two effects can be obtained.
(Effect 1) Since the starter can be stopped quickly, the use time of the starter can be shortened. As a result, deterioration of the starter is suppressed, and the effect of improving the durability of the starter is obtained.

(Effect 2) In the engine complete explosion rotation range, the driving torque of the motor generator is working. As a result, the auxiliary torque by the starter is not required, so that the starter can be set to low rotation and small output specifications, and the effect of downsizing can be obtained.

  In the first embodiment described above, the predetermined rotation speed is described as the rotation speed of the starter 3 when the crank angle of the engine 1 is top dead center. In this case, the rotation speed of the starter 3 may be used by measuring the actual rotation speed of the starter 3. However, when the actual rotation speed of the starter 3 is measured and used, a rotation sensor for measuring the rotation speed of the starter 3 is separately required.

  Therefore, the following method for obtaining the rotation speed of the starter 3 without using a rotation sensor for measuring the rotation speed of the starter 3 may be employed. In this method, according to the characteristics of the starter 3, the starter rotation speed is set in advance as a starter rotation speed map every predetermined time starting from the start point of the starter 3. Then, the rotation speed of the starter 3 when the crank angle of the engine 1 is at the top dead center can be derived by complementation from data of a preset starter rotation speed map.

  In the existing system, the rotational speeds of the engine 1 and the motor generator 2 can be monitored, but the rotational speed of the starter 3 cannot be monitored. For this reason, by preparing in advance a rotation speed map corresponding to the time from activation, it is not necessary to add a rotation sensor, and the effect of reducing the cost of the system can be obtained.

  Furthermore, the starter rotation speed map can be a plurality of map data corresponding to each predetermined temperature at a temperature related to the engine 1 such as an engine water temperature or an engine oil temperature. By using a plurality of map data in this manner, appropriate data can be set in consideration of changes in the characteristics of the starter 3 due to temperature changes and changes in the friction torque of the engine 1, and more accurate control is possible. A possible effect is obtained.

Embodiment 2. FIG.
In the first embodiment, the case where the predetermined rotation speed is the rotation speed of the starter 3 at that time has been described. On the other hand, in the second embodiment, a case will be described in which the predetermined rotational speed is set to a predetermined constant rotational speed.

  FIG. 3 is a flowchart showing the flow of the combined start control that is executed in the start controller 5 according to the second embodiment of the present invention. Compared with the flowchart of FIG. 2 in the first embodiment, the flowchart of FIG. 3 in the second embodiment differs in that the processing content of step S112 is different and that steps S123 and S124 are unnecessary. . Therefore, these differences will be mainly described below.

  In step S112 of FIG. 3 in the second embodiment, the start controller 5 monitors the current crank angle and determines whether or not the rotational speed of the engine 1 near the top dead center is equal to or higher than a predetermined rotational speed. To do.

  Here, in the second embodiment, when the predetermined rotational speed is set to, for example, a no-load rotational speed obtained from the characteristics of the starter 3, the start controller 5 at the top dead center in step S112. It is determined whether or not the rotational speed of the engine 1 is equal to or higher than the no-load rotational speed of the starter 3.

  At this time, the rotation speed of the engine 1 and the rotation speed of the starter 3 are compared with each other in consideration of the correlation between the rotation speed depending on the number of teeth of the ring gear 13 and the number of teeth of the pinion 31.

  As a result of the determination in step S112, when the rotational speed of the engine 1 at the top dead center is not equal to or higher than a predetermined rotational speed set in advance (NO), the rotational speed of the engine 1 at the top dead center is determined in advance. The state is maintained and waits until the speed reaches or exceeds a predetermined rotation speed.

  On the other hand, as a result of the determination in step S112, if the rotational speed of the engine 1 at the top dead center is equal to or higher than a predetermined rotational speed set in advance (YES), the process proceeds to step S113, and the previous embodiment 1 will be performed, and a description thereof will be omitted.

According to the start controller 5 configured as described above, the following features can be realized.
(Characteristic 1) By setting the predetermined rotation speed to be equal to or higher than the no-load rotation speed of the starter 3, that is, higher than the rotation speed at which the starter 3 cannot generate auxiliary torque, whether or not the starter 3 is unnecessary for starting the engine at that time. Can be determined. In other words, since it can be determined that the cranking is performed only by the driving torque of the motor generator 2, the starter 3 may be stopped.

As a result, according to the second embodiment, the following three effects can be obtained.
(Effect 1) Since the starter can be stopped quickly, the use time of the starter can be shortened. As a result, deterioration of the starter is suppressed, and the effect of improving the durability of the starter is obtained.

(Effect 2) In the engine complete explosion rotation range, the driving torque of the motor generator is working. As a result, the auxiliary torque by the starter is not required, so that the starter can be set to low rotation and small output specifications, and the effect of downsizing can be obtained.

(Effect 3) Furthermore, the rotational speed of the engine 1 at the top dead center can be compared with a constant value that is the no-load rotational speed of the starter. As a result, the control is simplified, the effect of improving controllability is obtained, and the need for adding a rotation sensor is eliminated, so that the cost of the system can be reduced.

  The predetermined rotational speed that is the no-load rotational speed of the starter can be a plurality of data corresponding to each predetermined temperature in the temperature related to the engine 1, such as the engine water temperature or the engine oil temperature. By using a plurality of data in this way, appropriate data can be set in consideration of changes in the characteristics of the starter 3 due to temperature changes and changes in the friction torque of the engine 1, and more accurate control is possible. The effect becomes.

Embodiment 3 FIG.
In the first and second embodiments, the combined start control including step S112 for determining whether or not the rotational speed of the engine 1 at the top dead center is equal to or higher than the predetermined rotational speed has been described. On the other hand, in the third embodiment, combined start control having a determination step different from step S112 will be described.

  FIG. 4 is a flowchart showing the flow of the combined start control that is executed in the start controller 5 according to the third embodiment of the present invention. Compared with the flowchart of FIG. 2 in the first embodiment, the flowchart of FIG. 4 in the third embodiment is different in that it includes steps S120 and S122 instead of the processes of steps S113 to S115. ing. Therefore, these differences will be mainly described below.

  In step S110, the start controller 5 determines whether or not there is an engine start request for starting the engine 1 based on an operation state signal indicating the operation state of the engine and the vehicle input to the engine ECU 6. .

  If the result of determination in step S110 is that there is no engine start request (NO), the start controller 5 maintains the state and waits until there is an engine start request. On the other hand, if the result of determination in step S110 is that there is an engine start request (YES), processing proceeds to step S111.

  In step S111, the start controller 5 drives the electromagnetic switch 32 to close the electrical contact. As a result, when the motor circuit is energized, current is supplied to the motor unit of the starter 3, auxiliary torque is generated in the motor unit, and the starter 3 is started.

  Further, by driving the electromagnetic switch 32 to close the electrical contact, the pinion 31 moves to a position where it engages with the ring gear 13. As a result, the auxiliary torque of the motor unit is transmitted to the crankshaft 11 via the meshed pinion 31 and the ring gear 13, and the engine 1 is driven to rotate. Then, fuel injection is started.

  Further, in step S <b> 111, the start controller 5 supplies power to the motor generator 2 through the inverter 21 controlled by the MG control circuit 22 using the power of the battery 4. As a result, the motor generator 2 is driven as a motor and drives the engine 1 by transmitting driving torque to the crankshaft 11 via the belt 12.

  After starting the engine, the engine ECU 6 determines the rotational speed of the engine 1, that is, the rotational speed of the ring gear 13, based on the current crank angle and the cycle of the crank angle signal obtained from the crank angle signal from the crank angle sensor 14. Is calculated and monitored.

  The start controller 5 starts the combined cranking by the starter 3 and the motor generator 2 in step S111, and then monitors the rotational speed of the engine 1 and the rotational speed of the motor generator 2 in step S120. Furthermore, the start controller 5 derives a relative rotational speed difference between the rotational speed of the engine 1 and the rotational speed of the motor generator 2, and the derived relative rotational speed difference is a first predetermined rotational speed set for determination. Determine if it is less than or equal to the difference.

  That is, this relative rotational speed difference corresponds to the slip of the belt 12 that always connects the engine 1 and the motor generator 2, and an allowable value for the slip of the belt 12 is preset as a first predetermined rotational speed difference. ing.

  At this time, the rotational speed of the engine 1 and the rotational speed of the motor generator 2 are compared with each other in consideration of the correlation between the rotational speeds of the pulley ratios of the pulleys on which the belt 12 is hung.

  If the result of determination in step S120 is that the relative rotational speed difference is less than or equal to the first predetermined rotational speed difference (YES), the process proceeds to step S123, and the start controller 5 causes the engine 1 to complete explosion. Whether or not the engine 1 has been started is determined.

  On the other hand, if the relative rotational speed difference is not less than or equal to the first predetermined rotational speed difference (NO), the process proceeds to step S122, and the start controller 5 proceeds to step S124 after reducing the drive torque of the motor generator 2. Then, it is determined whether or not the engine 1 has completely exploded.

  It is assumed that the reduction amount of the driving torque of the motor generator 2 in step S122 is reduced according to the relative rotational speed difference, or is reduced using a predetermined torque value set in advance.

  When the reduction amount is reduced according to the relative rotational speed difference, the current torque command value is changed to the torque command value according to the relative rotational speed difference. Further, when the torque is reduced using a predetermined torque value set in advance, the torque command value is changed to a torque command value obtained by subtracting the predetermined torque value from the current torque command value.

  As a result of the determination in step S123, if the engine 1 has not been started (NO), the start controller 5 performs the control from step S120 again until it is determined that the engine 1 has been started. To do.

  On the other hand, if the result of determination in step S123 is that the engine 1 has completely exploded (YES), the routine proceeds to step S124. In step S124, the start controller 5 stops the starter 3. That is, the state in which the pinion 31 is engaged with the ring gear 13 is eliminated, and the electrical contact of the electromagnetic switch 32 is opened, so that the power supply to the motor unit of the starter 3 is stopped. Furthermore, the start controller 5 stops the power supply to the motor generator 2 by the MG control circuit 22 and stops the function of the motor.

  By these series of processes, the combined start control by the motor generator 2 and the starter 3 in the engine start is completed.

According to the start controller 5 configured as described above, the following features can be realized.
(Characteristic 1) By comparing the rotational speeds of the engine 1 and the motor generator 2 during combined cranking, slippage of the belt 12 can be detected. When the belt 12 slips, it can be determined that the motor generator 2 is generating a driving torque that is greater than the transmission capability of the belt 12, and the slip of the belt 12 is reduced by reducing the driving torque. be able to. Therefore, unnecessary power consumption can be suppressed and consumption of mechanical parts such as the belt 12 and the pulley can be suppressed.

(Characteristic 2) The starter 3 is not stopped by the determination of only the slip of the belt 12, but the starter 3 is stopped after a complete explosion determination. As a result, it is possible to prevent the belt 12 from slipping again when the starter 3 is stopped.

(Characteristic 3) Furthermore, if the rotational speed near the top dead center where the rotational speed of the engine 1 drops during combined cranking is equal to or higher than the rotational speed at which the auxiliary torque of the starter 3 is not effective, it can be determined that the starter 3 can be stopped. . That is, since it can be determined that the cranking is performed only by the driving torque of the motor generator 2, the starter 3 can be stopped.

As a result, according to the third embodiment, the following two effects can be obtained.
(Effect 1) Since the starter can be stopped quickly, the use time of the starter can be shortened. As a result, deterioration of the starter is suppressed, and the effect of improving the durability of the starter is obtained.

(Effect 2) The frequency of using the starter until the engine complete explosion decreases, and the driving torque of the motor generator is working in the engine complete explosion rotation range. As a result, the auxiliary torque by the starter is not required, so the starter 3 can be set to a low rotation / small output specification, and the effect of downsizing can be obtained.

  In the third embodiment described above, the control for changing the drive torque command value of motor generator 2 is performed in step S122. However, the same effect can be obtained by the control for directly changing the current of motor generator 2. .

  Further, in determining the relative rotational speed difference, control may be performed based on the rotational speed of the engine 1 and the rotational speed of the motor generator 2 when the load of the engine 1 near the top dead center increases and the rotational speed drops. . In this case, by checking the relative rotational speed difference near the top dead center where the belt 12 is most likely to slip, there is no need to constantly check the relative rotational speed, making it possible to make more efficient determination and controllability. Improvement effect is obtained.

  Further, when the second predetermined rotational speed difference set for determination as a value equal to or smaller than the first predetermined rotational speed difference is used and the relative rotational speed difference is equal to or smaller than the second predetermined rotational speed difference, the engine is started. The controller 5 may determine that there is no slip of the belt 12, stop the starter 3, and perform cranking only with the motor generator 2.

  In this case, by stopping the starter 3 early, the use time of the starter 3 is shortened, so that the deterioration of the starter is suppressed. Furthermore, since the frequency of using the starter until the engine complete explosion is reduced and no auxiliary torque is required in the complete explosion rotation region, the low rotation specification can be achieved. Therefore, the effect of cost reduction by low durability and low rotation specifications can be obtained.

  When the relative rotational speed difference is equal to or smaller than the first predetermined rotational speed difference and the slip of the belt 12 is equal to or smaller than the allowable value, the start controller 5 determines the predetermined torque increase value from the current torque command value. The torque command value may be increased stepwise by performing control to change to a torque command value obtained by adding. At this time, it is desirable to increase the torque command value relatively gently while monitoring the relative rotational speed difference which is the slipping state of the belt 12.

Embodiment 4 FIG.
In the fourth embodiment, it is determined whether or not the rotational speed of the engine 1 near the top dead center is equal to or higher than a predetermined rotational speed with respect to the combined start control for starting the engine in the third embodiment. A case where the control of the first or second embodiment for stopping the starter 3 is added will be described.

  FIG. 5 is a flowchart showing the flow of combined start control that is executed in start controller 5 according to Embodiment 4 of the present invention. The flowchart in FIG. 5 according to the fourth embodiment is configured by combining the flowchart in FIG. 2 in the first embodiment and the flowchart in FIG. 4 in the previous third embodiment and further adding step S121. ing.

  Steps S110 and S111 are the same as those in the third embodiment, and a description thereof will be omitted.

  If the result of determination in step S120 is that the relative rotational speed difference is less than or equal to the first predetermined rotational speed difference (YES), the routine proceeds to step 121 where the start controller 5 determines that the relative rotational speed difference is the second predetermined rotational speed difference. It is determined whether or not the difference in rotation speed is less than or equal to. Here, the second predetermined rotation speed difference is set to be equal to or less than the first predetermined rotation speed difference.

  On the other hand, if the relative rotational speed difference is not equal to or less than the first predetermined rotational speed difference (NO), the process proceeds to step S122, and the start controller 5 reduces the drive torque of the motor generator 2 and then proceeds to step S123. move on.

  If the result of determination in step S121 is that the relative rotational speed difference is less than or equal to the second predetermined rotational speed difference (YES), the routine proceeds to step 112 where the start controller 5 monitors the current crank angle and It is determined whether or not the rotational speed of the engine 1 at the dead center is equal to or higher than a predetermined rotational speed.

  On the other hand, if the result of determination in step S121 is that the relative rotational speed difference is not less than or equal to the second predetermined rotational speed difference (NO), the process proceeds to step S123.

  As a result of the determination in step 112, if the rotational speed of the engine 1 at the top dead center is equal to or higher than the predetermined rotational speed (YES), the process proceeds to step S113, and the start controller 5 stops the starter 3. . That is, the state in which the pinion 31 is engaged with the ring gear 13 is eliminated, and the electrical contact of the electromagnetic switch 32 is opened, so that the power supply to the motor unit of the starter 3 is stopped.

  On the other hand, if the result of determination in step 112 is that the rotational speed of the engine 1 at the top dead center is not equal to or higher than the predetermined rotational speed (NO), the routine proceeds to step S123.

  The start controller 5 stops the starter 3 in step 113, and then determines in step S114 whether or not the engine 1 has completely exploded, that is, whether or not the engine 1 has been started. If the result of determination in step S114 is that engine 1 has not been started (NO), start controller 5 maintains the state and waits until it is determined that engine 1 has been started.

  On the other hand, if the result of determination in step S114 is that the engine 1 has completely exploded (YES), the routine proceeds to step S115. In step S115, the start controller 5 stops the power supply to the motor generator 2 by the MG control circuit 22 and stops the function of the motor.

  On the other hand, when the routine proceeds to step 123, the start controller 5 determines whether or not the engine 1 has completely exploded. As a result of the determination in step S123, if the engine 1 has not been started (NO), the start controller 5 performs the control from step S120 again until it is determined that the engine 1 has been started. To do.

  On the other hand, if the result of determination in step S123 is that the engine 1 has completely exploded (YES), the routine proceeds to step S124. In step S124, the start controller 5 stops the starter 3. That is, the state in which the pinion 31 is engaged with the ring gear 13 is eliminated, and the electrical contact of the electromagnetic switch 32 is opened, so that the power supply to the motor unit of the starter 3 is stopped.

  Furthermore, the start controller 5 stops the power supply to the motor generator 2 by the MG control circuit 22 and stops the function of the motor. By these series of processes, the combined start control by the motor generator 2 and the starter 3 in the engine start is completed.

According to the start controller 5 configured as described above, the following features can be realized.
(Characteristic 1) By comparing the rotational speeds of the engine 1 and the motor generator 2 during combined cranking, slippage of the belt 12 can be detected. When the belt 12 slips, it can be determined that the motor generator 2 is generating a driving torque that is greater than the transmission capability of the belt 12, and the slip of the belt 12 is reduced by reducing the driving torque. be able to. Therefore, unnecessary power consumption can be suppressed and consumption of mechanical parts such as the belt 12 and the pulley can be suppressed.

(Characteristic 2) The starter 3 is not stopped by the determination of only the slip of the belt 12, but the starter 3 is stopped after a complete explosion determination. As a result, it is possible to prevent the belt 12 from slipping again when the starter 3 is stopped.

(Characteristic 3) Further, by comparing the second predetermined rotational speed difference set to a value equal to or smaller than the first predetermined rotational speed difference and the relative rotational speed difference, it is determined that there is little or almost no slip of the belt 12. In addition, it can be determined that the starter 3 can be stopped if the rotational speed near the top dead center where the rotational speed of the engine 1 drops during the combined cranking is equal to or higher than the rotational speed at which the auxiliary torque of the starter 3 is not effective. That is, since it can be determined that the cranking is performed only by the driving torque of the motor generator 2, the starter 3 can be stopped.

As a result, according to the fourth embodiment, the following two effects can be obtained.
(Effect 1) Since the starter can be stopped quickly, the use time of the starter can be shortened. As a result, deterioration of the starter is suppressed, and the effect of improving the durability of the starter is obtained.

(Effect 2) The frequency of using the starter until the engine complete explosion decreases, and the driving torque of the motor generator is working in the engine complete explosion rotation range. As a result, the auxiliary torque by the starter is not required, so the starter 3 can be set to a low rotation / small output specification, and the effect of downsizing can be obtained.

  The second predetermined rotational speed difference may be set to a value smaller than the first predetermined rotational speed difference, and the safety factor against slipping of the belt 12 may be set large, or the first predetermined rotational speed is sufficient. If the safety factor is high, the same value may be used.

  Further, step S112 in FIG. 5 can use step S112 in FIG. 3 in the previous embodiment 2 instead of step S112 in FIG. 2 in the previous embodiment 1.

  In starting the engine 1 in the first to fourth embodiments described above, a specific example of the combined start control means has been described. However, the start controller 5 also includes single start control means for cranking the engine 1 with only the motor generator 2. Therefore, the two start control means, that is, the combined start control means and the single start control means, can be used properly according to predetermined conditions.

  For example, the combined start control is performed when the temperature of the engine 1 such as the engine water temperature or the engine oil temperature is equal to or lower than a predetermined temperature, and when the temperature is higher than the predetermined temperature, the motor generator 2 of the single start control is used. You may use properly so that starting may be implemented.

  Further, in a vehicle equipped with an idling stop function for automatically stopping and restarting the engine 1 according to the state of the vehicle, when the engine 1 is started by the driver's key operation, the combined start control is performed and the idling stop is performed. When the engine 1 is restarted from the stopped state by the above, the engine 1 may be started by the motor generator 2 of the single start control.

  When the two start control means, ie, the combined start control means and the single start control means are controlled to be used according to a predetermined condition, the start control method for the engine 1 includes the combined start control means and the motor adjuster. There are only two independent starting control means in the generator 2. For this reason, the starter 3 does not complete the start of the engine 1 alone. Therefore, it is possible to obtain the effect of downsizing and cost reduction by reducing the output of the starter 3 and the low rotation specification.

  Further, the slip of the belt 12 is likely to occur and the friction torque of the engine 1 is increased. When the engine temperature is equal to or lower than the predetermined temperature, the combined start control is performed, and the slip of the belt 12 is less likely to occur. When the engine temperature is higher than the predetermined temperature, the separate start control may be performed.

  Thus, by properly using the two start control means according to the temperature, the motor generator 2 and the starter 3 do not need to cope with a large friction torque at a low temperature, and the slip of the belt 12 is also suppressed. The Therefore, the effect of reducing the size and cost by reducing the output of the motor generator 2 and the starter 3 and the effect of improving the durability of the belt 12 can be obtained.

  In the combined start control of the engine 1 in the first to fourth embodiments described above, the start controller 5 has been described to start both the starter 3 and the motor generator 2 in step 111. At this time, the motor generator 2 may be started at the same time as the starter 3 is started, or the motor generator 2 may be started before or after the starter 3 is started. Is obtained.

  However, in the initial stage of the start, when the motor generator 2 is started to start cranking and the starter 3 is started with a delay time, the pinion 31 of the starter 3 is meshed with the ring gear 13 which has already started rotating. become. For this reason, it is desirable to start the motor generator 2 at the same time as the starter 3 is started or to start the motor generator 2 with a delay time with respect to the starter 3 being started.

  For example, after cranking is started only with the starter 3 and the rush current generated by starting the starter 3 is settled, or after the first compression process of the engine 1 after the starter 3 is started, Control for starting the motor generator 2 may be employed.

  In this case, it is possible to further suppress the voltage drop by not using the motor generator 2 when the voltage drops. As a result, it is possible to prevent the inverter driving the motor generator 2 and the motor control circuit from being reset due to a voltage drop.

  In addition, the motor generator 2 is not used in a region where the load is greatest at low temperatures, and it is possible not to start from a stopped state. As a result, the driving torque / current can be suppressed, and the effect of suppressing the increase in size of the motor generator 2 and the inverter 21 can be obtained.

  Furthermore, when the starter 3 is stopped in the first to fourth embodiments described above, it is determined whether the piston stroke of the engine 1 is in a stroke region including the stroke region immediately before the bottom dead center to the stroke region immediately after the top dead center. It is possible to predict, determine a time point at which the starter 3 and the engine 1 are to be released, and to release the connection. By executing such a release process, it is possible to suppress the generation of abnormal noise when releasing the connection.

  Furthermore, the starter 3 in the above-described first, second, and fourth embodiments does not rotate to the rotational speed of the complete explosion determination of the engine 1 over the lifetime, and is not rotated from the ring gear side. For this reason, even if the one-way clutch that is normally provided is not provided, the motor unit is not damaged by high rotation. As a result, the cost can be further reduced by eliminating the one-way clutch.

  In the first to fourth embodiments described above, power is supplied to the motor generator 2 and the starter 3 by one battery 4, and the motor generator 2 and the starter 3 are described as a system that is used at the same voltage. Yes. However, the present invention is not limited to such a case. For example, the present invention can be applied to specifications in which the motor generator 2 is used at a higher voltage than the starter 3.

  In the case of such a specification, for example, a step-down DC / DC converter that steps down the voltage of the battery 4 is required between the battery 4 and the starter 3. Further, a separate battery may be connected to each of the motor generator 2 and the starter 3, and the voltage is not particularly limited. In addition, another power source such as a capacitor may be used instead of the battery.

  DESCRIPTION OF SYMBOLS 1 Engine, 2 Motor generator (1st electric motor), 3 Starter (2nd electric motor), 4 Battery, 5 Engine starting control apparatus, 6 Engine control apparatus (engine ECU), 11 Crankshaft, 12 Belt, 13 Ring gear, 14 Crank Angle sensor, 21 inverter, 22 motor generator control circuit (MG control circuit), 31 pinion, 32 electromagnetic switch.

An engine start control device according to the present invention includes a first electric motor that is always connected to an engine by a belt and generates a driving torque at the time of starting the engine to perform cranking; A second motor that performs cranking by generating an engine, a start controller that uses both the first motor and the second motor to crank the engine at the time of engine start, and an engine speed detection that detects the engine speed And an engine start control device having a first motor rotation speed detector for detecting the rotation speed of the first motor, wherein the start controller is an engine detected by the engine rotation speed detector during combined cranking. The relative rotational speed difference between the rotational speed of the motor and the rotational speed of the first motor detected by the first motor rotational speed detector is derived. , The relative rotational speed difference derived in top dead center of the engine is greater than the first determination rotation speed difference is used to adjust the direction of lowering the driving torque of the first electric motor.

In addition, the engine start control method according to the present invention includes a first electric motor that is always connected to the engine by a belt and generates a driving torque when starting the engine to perform cranking, and is connected to the engine by a gear when starting the engine. A second electric motor that cranks by generating auxiliary torque, a start controller that uses the first electric motor and the second electric motor together to crank the engine when the engine is started, and an engine rotation that detects the rotational speed of the engine An engine start control method executed by an engine start control device having a speed detector and a first motor rotation speed detector for detecting a rotation speed of a first motor, wherein the engine controls the engine with respect to the engine. A first step for determining whether or not a start request has occurred, and an engine start request is generated by the first step. Is determined by the engine speed detector after the combined cranking is started by the second step, and the combined cranking of the engine is started by the second step. A third step of deriving a relative rotational speed difference between the rotational speed of the engine and the rotational speed of the first motor detected by the first motor rotational speed detector; and a third step at the top dead center of the engine. When the relative rotational speed difference is larger than the first determination rotational speed difference, there is a fourth step of adjusting the drive torque of the first electric motor to decrease.

Claims (11)

A first electric motor that is always connected to the engine by a belt and generates a driving torque when the engine is started to perform cranking;
A second electric motor connected to the engine by a gear at the time of starting the engine and generating an auxiliary torque to perform cranking;
A start controller for simultaneously cranking the engine by using the first electric motor and the second electric motor at the time of starting the engine;
An engine speed detector for detecting the engine speed;
An engine start control device comprising: a first motor rotation speed detector that detects a rotation speed of the first motor;
The start controller is
A relative rotational speed difference between the rotational speed of the engine detected by the engine rotational speed detector during the combined cranking and the rotational speed of the first motor detected by the first motor rotational speed detector is derived. And
An engine start control device that adjusts the driving torque of the first electric motor to be decreased when the relative rotational speed difference is larger than a first determination rotational speed difference. When the start controller determines that the relative rotational speed difference is larger than the first determination rotational speed difference during the combined cranking, the first motor causes the first motor to generate the drive torque. The engine start control device according to claim 1, wherein the torque command value is changed to a torque command value obtained by subtracting a predetermined subtraction torque amount from the current torque command value. If the start controller determines that the relative rotational speed difference is greater than the first determination rotational speed difference during the combined cranking, the starter controller determines whether the first electric motor is in accordance with the relative rotational speed difference. 2. The engine start control according to claim 1, wherein a subtraction torque amount for reducing a torque command value for generating the drive torque is derived and changed to a torque command value obtained by subtracting the subtraction torque amount from a current torque command value. apparatus. The start controller is
When it is determined that the relative rotational speed difference is larger than the first determination rotational speed difference during the combined cranking, the relative rotational speed difference is smaller than the first determination rotational speed difference. It is determined whether or not the second determination rotational speed difference is less than,
The rotational speed at the top dead center of the engine that is determined by the engine rotational speed detector to determine that the relative rotational speed difference is equal to or less than the second determination rotational speed difference and during the combined cranking. If it determines with these being more than the rotational speed for determination, while releasing the connection with the said engine of the said 2nd electric motor with the said engine, a said 2nd electric motor is stopped. The engine start control device according to Item. 5. The engine start control device according to claim 4, wherein the start controller uses a rotation speed at the crankshaft of the engine corresponding to a no-load rotation speed of the second electric motor as the determination rotation speed. A second motor rotation speed detector for detecting the rotation speed of the second motor;
The engine start control device according to claim 4, wherein the start controller uses a rotation speed of the second motor detected by the second motor rotation speed detector as the determination rotation speed. The start controller is
Having a second motor rotation speed map preliminarily defining the correspondence between the elapsed time and the rotation speed of the second motor, starting from the starting point of the second motor;
The engine start control device according to claim 4, wherein the determination rotational speed is derived from the second motor rotational speed map in accordance with an elapsed time from a start time of the second motor. A first electric motor that is always connected to the engine by a belt and generates a driving torque when the engine is started to perform cranking;
A second electric motor connected to the engine by a gear at the time of starting the engine and generating an auxiliary torque to perform cranking;
A start controller for simultaneously cranking the engine by using the first electric motor and the second electric motor at the time of starting the engine;
An engine speed detector for detecting the engine speed;
An engine start control method executed by an engine start control device having a first motor rotation speed detector for detecting a rotation speed of the first motor,
In the start controller,
A first step of determining whether an engine start request has occurred for the engine;
A second step of using the first electric motor and the second electric motor together to crank the engine together when it is determined that the engine start request has occurred in the first step;
After the combined cranking is started in the second step, the engine rotation speed detected by the engine rotation speed detector, and the rotation speed of the first motor detected by the first motor rotation speed detector. A third step of deriving a relative rotational speed difference of
A fourth step of adjusting the drive torque of the first electric motor in a direction to decrease when the relative rotational speed difference derived in the third step is larger than the first determination rotational speed difference. Control method. In the second step, when it is determined in the first step that the engine start request has occurred,
A condition determination step for determining whether or not a combination start condition set in advance is satisfied;
Combined start control for executing combined start control for cranking the engine by using the first motor and the second motor together when it is determined in the condition determining step that the combined start condition is satisfied. Steps,
9. A single start control step for executing a single start control for cranking the engine with only the first electric motor when it is determined in the condition determination step that the combined start condition is not satisfied. The engine start control method described in 1. The second step further includes a temperature detection step of reading a temperature related to the engine detected by an engine temperature detector,
The condition determining step in the second step determines that the combined start condition is satisfied when the temperature of the engine detected in the temperature detecting step is equal to or lower than a preset temperature. The engine start control method according to claim 9. In the condition determination step in the second step, when applying the combined start control to a vehicle equipped with an idling stop function that automatically stops and restarts the engine according to the state of the vehicle,
When the engine is started by the driver's key operation, it is determined that the combined start condition is satisfied,
The engine start control method according to claim 9 or 10, wherein it is determined that the combined start condition is not satisfied when the engine is restarted from an idle state due to idling stop.

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