JP5271226B2 - Engine starter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine starter in a simple constitution which attains exact prevention of belt slip when starting the engine. <P>SOLUTION: An ECU 50 controls a starting torque Tq generated by a motor generator 15 when starting the engine 1 by using starting time ts when an output rotation frequency N of the motor generator 15 reaches a target rotation frequency Nt, and variably controls the starting time ts based on the oil temperature of working fluid of a tensioner 28. Thereby, the belt slip when starting the engine 1 can be exactly prevented in the simple constitution without performing a current feedback control and an adhesion control, etc. for the motor generator 15. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an engine starter that transmits a driving force generated by an electric motor to a crankshaft via a belt when the engine is started.

  In recent years, a so-called idling stop system that stops an engine at idling has been developed as part of a measure for reducing exhaust gas by improving fuel efficiency. In a vehicle that employs such an idling stop system, it is possible to effectively reduce exhaust gas, particularly when traveling in an urban area where start and stop are frequently repeated.

  On the other hand, when the idling stop control is performed, the number of engine starts is significantly increased as compared with the case where the idling stop control is not performed. Therefore, the engine starter used in the idling stop system is required to have high durability, low vibration noise, and the like, and it is difficult to directly apply a gear type starter that assumes only the start at the beginning of traveling. It was. Therefore, this type of engine starting device tends to employ a belt type starter that transmits the rotation of a starter motor (electric motor) to the engine by a belt to start the engine.

  Here, it is common that the generator of the belt type starter is also used as a generator such as an alternator. In such a case, the motor (motor generator) generally has a belt together with other auxiliary machines. To the crank pulley. Therefore, this type of belt system is provided with a tensioner for preventing belt slippage due to rush torque from the electric motor at the time of starting, and a predetermined tension is applied to the belt by this tensioner ( For example, see Patent Document 1).

  In this case, in order to enable starting in a cold state in which engine friction is maximum, the tensioner generally has a tensile force applied when a tensile force acts on the belt by a transmission torque from the electric motor during the cold starting of the engine. Leak-down characteristics (damping characteristics) that can repel forces are set.

JP-A-11-190222

  However, especially in vehicles that employ an idling stop system, it is necessary to frequently start the engine under a wide range of conditions from cold to warm-up, and each start condition such as engine friction and tensioner characteristics is Since it changes between when it is cold and when it is warming up, it may be difficult to accurately prevent belt slip by simply performing uniform starting control based on the time when it is cold.

  To deal with this, for example, it may be possible to prevent belt slip at the start by performing current feedback control, adhesion control, etc. on the motor, but these controls require a current sensor, a high-precision rotation sensor, etc. Therefore, it becomes a factor of cost increase.

  On the other hand, it may be possible to set the damping characteristics of the tensioner to a predetermined value higher than that of the engine when the engine is cold. In such a case, however, the friction of the belt system will increase excessively and fuel consumption will deteriorate. Etc. may be caused.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an engine starter capable of accurately preventing belt slip at the time of start-up with a simple configuration.

  The present invention includes a crank pulley fixed to a crankshaft of an engine, an auxiliary pulley fixed to a rotating shaft of an electric motor, a belt wound around the crank pulley and the auxiliary pulley, and the belt A hydraulic tensioner that applies tension, and a control unit that starts the engine through output control of the electric motor, the control unit until the output rotational speed of the electric motor reaches a target rotational speed when the engine is started. The starting time is variably controlled according to the oil temperature of the tensioner.

  According to the engine starting device of the present invention, belt slip at the time of starting can be accurately prevented with a simple configuration.

Schematic configuration diagram showing the engine starter Characteristic diagram showing the relationship between the hydraulic fluid temperature of the tensioner and the leak-down characteristics Characteristic diagram showing motor control characteristics at engine start Flow chart showing engine start control routine Characteristic chart showing tensioner expansion and contraction characteristics at engine start Schematic configuration diagram showing a modification of the engine belt system

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings relate to an embodiment of the present invention, FIG. 1 is a schematic configuration diagram showing an engine starting device, FIG. 2 is a characteristic diagram showing a relationship between a hydraulic oil temperature of a tensioner and a leak-down characteristic, and FIG. FIG. 4 is a flow chart showing an engine start control routine, FIG. 5 is a characteristic view showing a tensioner expansion / contraction characteristic at the time of engine start, and FIG. 6 is a schematic configuration showing a modification of the engine belt system. FIG.

  An engine 1 shown in FIG. 1 is, for example, a horizontally opposed engine having an idling stop function. The engine body 5 of the engine 1 has a pair of left and right cylinder blocks 6.

  Each cylinder block 6 includes a cylinder 7 and a crankcase half 8 integrally formed on the base side of the cylinder 7. The base end portions of the crankcase half bodies 8 are joined to each other, whereby a crankcase is formed in the center portion of the engine body 5. Moreover, each cylinder 7 is arrange | positioned at the both sides of a crankcase, and the cylinder head 9 is each attached to the top part.

  A crankshaft 10 is rotatably supported at a joint portion of the crankcase half 8 via a bearing (not shown). A crank pulley 11 is fixed to the crankshaft 10 on the front side of the engine body 5. Has been.

  Various auxiliary machines such as a motor generator 15, a power steering oil pump 16, and an air conditioner compressor 17 are disposed on the upper portion of the engine body 5. A motor generator pulley 18, an oil pump pulley 19, and a compressor pulley 20, which are auxiliary pulleys, are respectively fixed to the rotary shafts 15 a to 17 a of the auxiliary machinery 15 to 17, and these are the same plane as the crank pulley 11. It is arranged on the top.

  The pulleys 18 to 20 and the crank pulley 11 constitute a belt system capable of transmitting power to each other by winding a series of belts 21. Thus, when the engine 1 is driven, the engine driving force from the crank pulley 11 is transmitted to the motor generator 15, the power steering oil pump 16, and the air conditioner compressor 17 via the belt 21. On the other hand, when the engine 1 is started, when the motor generator 15 is driven as an electric motor through control from an electronic control unit (ECU) 50 described later, the driving force generated by the motor generator 15 is transmitted via the belt 21 to the crank pulley 11. Is transmitted to.

  Here, in the belt system having such a configuration, an idler pulley 22 is disposed between the motor generator pulley 18 and the oil pump pulley 19. The idler pulley 22 is rotatably supported by the engine body 5 via a bracket (not shown) and is in contact with the belt 21 from the outer surface side. A part of the belt 21 is bent inward by the contact of the idler pulley 22, so that the belt 21 is wound around the motor generator pulley 18 and the oil pump pulley 19.

  An auto tensioner 25 is disposed between the crank pulley 11 and the oil pump pulley 19. In the present embodiment, the auto tensioner 25 is, for example, an arm 26 whose one end is pivotally supported by the power steering oil pump 16 via a pivot 26 a and is pivotally supported on the other end of the arm 26. The belt tensioner pulley 27 is configured to include a hydraulic tensioner 28 having a fixed end connected to the engine body 5 and a free end connected to the middle of the arm 26. The auto tensioner 25 applies a predetermined tension to the belt 21 by urging the belt 21 from the outer surface side via the belt tensioner pulley 27.

  Here, the tensioner 28 of the present embodiment has its leak-down characteristic (damping characteristic) and the like set based on the starting condition in the cold state where the engine friction is maximum. That is, in order to prevent excessive friction or the like from being generated in the belt system due to excessive application of tension to the belt 21, the damping characteristic of the tensioner 28 is set such that the predetermined starting torque Tq0 required at the cold start is set to the motor generator 15 Even when it is generated by the above, the characteristic is set to be necessary and sufficient to prevent belt slip.

  On the other hand, the damping force of the hydraulic tensioner 28 greatly depends on the viscosity of the hydraulic oil sealed inside, and the viscosity of the hydraulic oil decreases as the temperature rises. Therefore, for example, as shown in FIG. 2, the damping force (leakdown time) of the tensioner 28 decreases as the temperature rises. In this case, assuming that when the engine 1 is started with the above-described starting torque Tq0, the leak-down time that guarantees the prevention of belt slip is 3.2 (s / mm), in the example of FIG. When the temperature (oil temperature) T of the tensioner 28 is equal to or higher than 38 ° C., the possibility of occurrence of belt slip increases.

  Therefore, in the present embodiment, the ECU 50 determines the time (start-up time) until the output rotational speed N of the motor generator 15 at the time of starting the engine reaches the target rotational speed Nt according to the oil temperature T of the hydraulic oil inside the tensioner 28. By performing variable control in this way, substantial control of the starting torque Tq is performed, and the occurrence of belt slip is suppressed.

  Specifically, the ECU 50 stores, for example, a cold-time characteristic and a warm-up characteristic as control characteristics for the motor generator 15 at the time of starting the engine, and the ECU 50 stores these control characteristics. Is selectively used according to the oil temperature T to perform start control of the engine 1. In this case, as shown in FIG. 3, for example, as shown in FIG. 3, the ECU 50 takes the output rotation speed N of the motor generator 15 at the start of the engine over a set activation time ts1 (for example, ts1 = 0.5 seconds). A control value for increasing the target rotational speed Nt is mapped and stored. Further, as a warm-up characteristic, for example, as shown in FIG. 3, the ECU 50 sets the output rotation speed N of the motor generator 15 at the time of engine start to a target rotation over a set start time ts2 (for example, ts2 = 1 second). Control values for increasing to several Nt are mapped and stored.

  Here, the oil temperature T can be detected directly using a dedicated thermistor or the like, but it is desirable to estimate it based on the detected temperature on the engine body 5 side in order to simplify the configuration. For example, the oil temperature T can be estimated based on at least one of the engine oil temperature detected by the oil temperature sensor 51 and the engine cooling water temperature detected by the water temperature sensor 52. In the present embodiment, the ECU 50 includes, for example, a map for estimating the oil temperature of the tensioner 28 based on the engine oil temperature, a map for estimating the oil temperature of the tensioner 28 based on the engine cooling water temperature, and the like. For example, the ECU 50 estimates the oil temperature estimated from each map as a high oil temperature T of the tensioner 28 from a high temperature.

  Thus, in this embodiment, ECU50 implement | achieves the function as a control means.

  Next, engine start control executed by the ECU 50 will be described with reference to a flowchart of an engine start control routine shown in FIG. This routine is executed, for example, when it is determined that the engine 1 is started based on a signal from an ignition switch or the like (not shown), or based on a signal from an accelerator pedal sensor or a brake pedal sensor (not shown) when idling is stopped. When the routine is started, the ECU 50 first estimates the oil temperature T of the hydraulic oil in the tensioner 28 in step S101. That is, the ECU 50 estimates the oil temperature of the tensioner 28 from a map or the like based on the engine oil temperature detected by the oil temperature sensor 51, and determines the tensioner 28 from the map or the like based on the engine water temperature detected by the water temperature sensor 52. The oil temperature is estimated, and the oil temperature of these is estimated as the final oil temperature T of the tensioner 28.

  Then, when the process proceeds from step S101 to step S102, the ECU 50 checks whether or not the oil temperature T estimated in step S101 is equal to or lower than a preset threshold value T0. In the present embodiment, for example, the threshold value T0 is set to 38 ° C., and when the ECU 50 determines that the oil temperature T is equal to or lower than the threshold value T0, the process proceeds from step S102 to step S103, and the control characteristics for the motor generator 15 are as follows. After selecting the cold state characteristics, the process proceeds to step S105.

  On the other hand, if it is determined in step S102 that the oil temperature T is higher than the threshold value T0, the ECU 50 proceeds to step S104, selects a warm-up characteristic as a control characteristic for the motor generator 15, and then proceeds to step S105.

  Then, when the process proceeds from step S103 or step S104 to step S105, the ECU 50 performs start control (cranking control) of the engine 1 through output control of the motor generator 15 based on the selected control characteristics, and then exits the routine.

  That is, when the cold state characteristic is selected, the ECU 50 performs control to increase the rotational speed N of the motor generator 15 to the target rotational speed Nt over a relatively short startup time ts1. In this way, by increasing the rotational speed N of the motor generator 15 to the target rotational speed Nt in a short time, a starting torque Tq sufficient to start the engine 1 is generated even in a cold state where the friction of the engine body 5 is high. It becomes possible to make it. Of course, in the cold state, a sufficient damping force with respect to the starting torque Tq is generated by the tensioner 28. Therefore, even when the tension of the belt 21 is increased by the starting torque (rush torque) Tq, the tensioner 28 The reaction force is maintained (see FIG. 5A), and the occurrence of belt slip can be accurately prevented.

  On the other hand, when the warm-up characteristic is selected, the ECU 50 performs control to increase the rotational speed N of the motor generator 15 to the target rotational speed Nt over a longer startup time ts2 than the cold characteristic. Then, by increasing the rotational speed N of the motor generator 15 to the target rotational speed Nt in a relatively long time, the motor generator 15 generates a starting torque Tq that is relatively lower than that in the cold state. At the time of warm-up when the friction on the main body 5 side is low, it is possible to ensure a sufficient starting torque for starting the engine 1. In addition, since the starting torque Tq generated by the motor generator 15 is kept low, the reaction force of the tensioner 28 against the belt 21 is maintained even when the damping force is reduced (see FIG. 5B), and belt slip occurs. Can be accurately prevented. For example, as shown by the alternate long and short dash line in FIG. 5B, when starting control of the engine 1 is performed using the cold characteristics during warm-up, the belt against the thrust (damping force) of the tensioner 28 When the tension of the belt 21 is won, the tensioner 28 is pushed back and the tension of the belt 21 is lowered, belt slip occurs.

  According to such an embodiment, the starting torque Tq generated by the motor generator 15 when the engine 1 is started is controlled using the starting time ts until the output rotational speed N of the motor generator 15 reaches the target rotational speed Nt. Then, the start time ts is variably controlled based on the oil temperature T of the hydraulic oil of the tensioner 28, so that the belt slip at the start-up can be performed with a simple configuration without performing current feedback control or adhesion control for the motor generator 15. Can be accurately prevented. More specifically, focusing on the fact that when the engine 1 is warmed up, the engine friction is reduced while the oil temperature T of the tensioner 28 is high and the damping force is reduced, the startup time ts2 at the time of warming up is cooled. By setting the start time Ts1 longer than the start time ts1 and keeping the start torque Tq generated by the motor generator 15 low, the occurrence of belt slip can be suppressed accurately even during warm-up, and the engine 1 can have good startability. be able to. In other words, belt slip can be prevented accurately and a good startability of the engine 1 can be obtained by simple control that only variably controls the starting time ts of the motor generator 15 during cold and warm-up. Can do.

  In the above-described embodiment, an example in which the idler pulley 22 is disposed between the motor generator pulley 18 and the oil pump pulley 19 and the auto tensioner 25 is disposed between the crank pulley 11 and the oil pump pulley 19. However, these arrangements are not limited to those described above. For example, the idler pulley 22 is moved between the crank pulley 11 and the oil pump pulley 19 as shown in FIG. It is also possible to arrange the tensioner 25 between the motor generator pulley 18 and the oil pump pulley 19.

DESCRIPTION OF SYMBOLS 1 ... Engine 5 ... Engine main body 6 ... Cylinder block 7 ... Cylinder 8 ... Crankcase half body 9 ... Cylinder head 10 ... Crankshaft 11 ... Crank pulley 15 ... Motor generator (electric motor)
16 ... Oil pump for power steering 17 ... Compressor for air conditioner 18 ... Motor generator pulley (auxiliary pulley)
DESCRIPTION OF SYMBOLS 19 ... Oil pump pulley 20 ... Compressor pulley 21 ... Belt 22 ... Idler pulley 25 ... Auto tensioner 26 ... Arm 26a ... Pivot 27 ... Belt tensioner pulley 28 ... Tensioner 50 ... Electronic control unit (control means)
51 ... Oil temperature sensor 52 ... Water temperature sensor

Claims (3)

A crank pulley fixed to the crankshaft of the engine;
An auxiliary pulley fixed to the rotating shaft of the electric motor;
A belt wound around the crank pulley and the auxiliary pulley;
A hydraulic tensioner that applies tension to the belt;
Control means for starting the engine through output control of the electric motor,
The engine starter characterized in that the control means variably controls the start-up time until the output rotational speed of the electric motor reaches the target rotational speed when the engine is started according to the oil temperature of the tensioner.   2. The engine starter according to claim 1, wherein the control unit sets the start-up time when the oil temperature of the tensioner is high as compared to when the oil temperature is low.   3. The engine starter according to claim 1, wherein the control unit estimates an oil temperature of the tensioner based on at least one of an engine oil temperature and an engine coolant temperature. 4.

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