WO2005068827A1

WO2005068827A1 - Controller controlling electric machine operated to start internal combustion engine

Info

Publication number: WO2005068827A1
Application number: PCT/JP2004/017999
Authority: WO
Inventors: Hiroaki Tabuchi; Mitsukazu Hattori
Original assignee: Toyota Jidosha Kabushiki Kaisha; Denso Corporation
Priority date: 2004-01-19
Filing date: 2004-11-26
Publication date: 2005-07-28
Also published as: CN1906406A; KR100759059B1; EP1709323A1; JP2005201213A; KR20060118590A; JP4166160B2; CN100497934C

Abstract

An ECU executes a program including the steps of: outputting a start command signal to a starter (S100); determining whether an engine has been ignited (S200); if the engine is not ignited (NO at S200), detecting the engine's rate of rotation (S300) and when the engine's rate of rotation attains an upper limit or more (YES at S400), then outputting a stop command signal to the starter (S500); and after the stop command signal has been output to the starter when the engine is inertially rotating before the engine's rate of rotation attains a lower limit or less (NO at S700), continuing a process for igniting the engine, and determining whether the engine has been ignited (S800).

Description

DESCRIPTION

Controller Controlling Electric Machine Operated to Start Internal Combustion Engine

Technical Field The present invention relates generally to electric machines operated to start internal combustion engines mounted on vehicles and particularly to controllers controlling the electric machines.

Background Art Vehicles have mounted thereon an internal combustion engine capable of continuing to operate on kinetic energy generated by itself once it has started operation. To start the engine, however, an air fuel mixture must be intaken and compressed, and the engine accordingly requires external kinetic energy. Accordingly a starter device referred to as a starter motor is introduced. The starter motor has an end provided with a pinion gear (an external gear). Furthermore the engine has a crank shaft having an end provided with a flywheel surrounded by an external gear. The starter motor's pinion gear and the flywheel's external gear are meshed by using a magnet switch and a secondary battery is used to power and thus actuate the starter motor to rotate (or crank) the crank shaft to start the engine. There also exists a starter motor dispensing with such a pinion gear and allowing a pulley for the crank shaft of the engine and that for the rotation shaft of the starter motor to be connected by a belt. To start the engine, a secondary battery powers and thus actuates the starter motor, and the belt transmits power from the pulley for the rotation shaft of the starter motor to that for the crank shaft of the engine to rotate (or crank) the crank shaft to start the engine. For such an engine starter, publications disclose conventional art, as described hereinafter: Japanese Patent Laying-open No. 1-88076 discloses an engine starter controller avoiding deficiency associated with setting a starter motor at a high rate of rotation to early scavenge inflated gas to eliminate poor startability attributed to a fuel leaking from a fuel injected engine's injector, a carburetor, or the like and inflated in an intake pipe at warm start. The engine starter controller allows the starter motor to be linked to the engine via a switching mechanism and includes a temperature sensor detecting the temperature of the engine, and control means receiving an output of the temperature sensor and driven by the engine's temperature to switch the switching mechanism to change a cranking rotation rate to start the engine. In this engine starter controller the control means can be driven by the engine's temperature to change a cranking rotation rate to be an optimal rotation rate to prevent high cranking rotation rate contributing to disadvantageously reduced battery voltage in starting the engine. More specifically, at warm start the control means controls the switching means to provide an increased cranking rotation rate. This immediately scavenges excessively dense air fuel mixture filling the intake pipe and thus provides improved startability. At other start time when the intake pipe is not filled with excessively dense air fuel mixture the control means controls the switching means so that a cranking rotation rate is not increased and reduced battery voltage can thus be avoided. Japanese Patent Laying-open No. 5-133309 discloses an engine starter that prevents excessive burden on a starter motor powered by a battery to start an engine and also prevents excessive discharge from the battery to appropriately start the engine. The engine starter provided with the battery powered and thus operated starter motor operated to start the engine, includes a controller performing a first process halting the starter motor for more than a prescribed period of time when the starter motor is operated for at least a prescribed period of time and the engine still does not reach a prescribed rate of rotation, and a second process setting the engine in unstartable state when the first process is repeated at least a prescribed number of times and the engine still does not reach the prescribed rate of rotation. For this engine starter when the starter motor is operated for a prescribed period of time and the engine still does not reach a prescribed rate of rotation the controller performs a first process to halt the starter motor for more than a prescribed period of time. Conventionally, when a starter motor is operated and despite that the engine has failed to start, the starter motor's operation is stopped and immediately thereafter it is restarted. In contrast, the disclosed controller can prevent the starter motor from experiencing excessive burden and the battery from excessively discharging. When the first process is repeated at least a prescribed number of times and the engine still does not reach the prescribed rate of rotation the controller performs a second process to set the engine in unstartable state. This state exacts checking, repairing, or other similar operation to remove the cause of the failure, and can prevent indiscriminately starting the engine. The engine starter controller disclosed in Japanese Patent Laying-open No. 1-

88076, however, has the following disadvantage: during cranking by the starter motor the engine's oil pump insufficiently functions for example. As such, increasing the cranking rotation rate may impair the engine, the transmission and the like in durability as their gears, bearings and the like are insufficiently lubricated. In such a case, to provide the engine with startability as well as durability the cranking rotation rate by the starter motor must be controlled within a narrow range precisely. It is known, however, that a cranking rotation rate depending on a starter motor significantly varies as it is affected by the battery's availability, the engine's variation in rotation resistance and the like. It is thus difficult to control within the narrow range. Furthermore it invites increased cost to mount a controller controlling a cranking rotation rate depending on a starter motor for such control. The engine starter disclosed in Japanese Patent Laying-open No. 5-133309 has the following disadvantage: when the starter motor is operated for a prescribed period of time and despite that the engine still does not reach a prescribed rate of rotation the controller performs a first process to halt the starter motor for more than a prescribed period of time. Whether the engine may have not reached the prescribed rate of rotation or have completely stopped rotating, the control to start the engine would stop. As such, once the first process has been entered, the engine will not start in spite that it is inertially rotating. As has been described above, higher cranking rotation rates provide improved engine startability for a variety of reasons. Accordingly if cranking by a starter motor is stopped there is a period of time for which the engine rotates inertially at a rate of rotation or higher that allows the engine to start. If during this period of time the control to start the engine is interrupted and the engine is not ignited the engine will not start in spite that the engine rotates at a rate allowing the engine to start.

Disclosure of the Invention The present invention has been made to overcome the above described disadvantages and it contemplates a controller controlling an electric machine operated to start an internal combustion engine that can implement satisfactory startability without incorporating a particular device inviting increased cost. The present controller controls an electric machine operated to start an internal combustion engine. The electric machine receives power from an electricity storage mechanism. The controller includes: a detection portion detecting a rate of rotation of the internal combustion engine; a start detection portion detecting that the internal combustion engine has started; and a control portion interrupting power supplied to the electric machine and also continuing a process for starting the internal combustion engine when the electric machine cranks the internal combustion engine and the internal combustion engine attains at least a predetermined rate of rotation, and the start detection portion nevertheless does not detect that the internal combustion engine has started. In accordance with the present invention the electric machine includes a starter motor, a starter generator and the like (hereinafter simply referred to as a "starter"), and it is mounted on a vehicle and cranks an internal combustion engine via a belt, a gear and/or the like. The starter is powered by a secondary battery corresponding to the electricity storage mechanism. As the starter cranks the engine the detection portion detects an increasing rate of rotation of the engine. The increasing rate of rotation reaches a prescribed rate of rotation, which is an upper limit of the rate of rotation set to protect the durability of the engine, transmission and the like when the air fuel mixture in the combustion chamber of the engine is not ignited and the engine does not start, and the starter cranks. When the upper limit is reached and the start detection portion still does not detect that the engine has started the power supplied to the starter is interrupted. The start detection portion detects for example from a rapidly increased rate of rotation of the engine that the engine has started. Reduced starter energization time can be achieved, and this provides increased life of a sliding portion of a motor brush or the like of the starter, prevents a temporarily reduced output attributed to the starter's self heat generation, and contributes to conserved power. If the power supplied to the starter is interrupted the engine will not immediately stop. More specifically, a flywheel or the like connected to the crank shaft of the engine acts to allow the engine to inertially rotate for a period of time. If the power supplied to the starter is interrupted the control portion still continues a process to start the engine.

More specifically, it continues a process to ignite an air fuel mixture introduced into the engine's combustion chamber. If the engine that is inertially rotating has a prescribed rate of rotation or higher, the engine can be started. By continuing the ignition process for a range of a rate of rotation of the engine as described above, (i.e., a range lower than a predetermined rate of rotation and at least a prescribed rate of rotation allowing the engine to start) the engine can be started if the power supplied to the starter is interrupted. A reduced cranking rotation rate can be provided to prevent a problem in durability of the engine, the transmission and the like attributed to the starter, and furthermore when power supplied to the starter is interrupted and the engine is still, initially rotating, the air fuel mixture in the combustion chamber of the engine can be ignited to start the engine. As a result there can be provided a controller controlling an electric machine operated to start an internal combustion engine that implements satisfactory engine startability without incorporating a particular device inviting increased cost. More preferably the control portion may exert control to continue the process for starting the internal combustion engine when power supplied to the electric machine is interrupted and the internal combustion engine is nevertheless inertially rotating. For example when the power supplied to the starter is interrupted and despite that the engine is still, inertially rotating, the control portion can provide control to continue a process to start (or ignite) the engine. The engine can be started while it is inertially rotating. Still preferably the control portion may exert control to continue the process for starting the internal combustion engine when the internal combustion engine is inertially rotating at at least a predetermined rate of rotation. The prescribed rate of rotation for example includes a minimum rate of rotation required to start the engine and a minimum rate of rotation allowing the engine to be ignited satisfactorily. If the engine is inertially rotating at at least the prescribed rate of rotation the process to start or ignite the engine continues. The engine can thus be stared if the power supplied to the starter is interrupted. Still preferably the process for starting the internal combustion engine is a process for igniting an air fuel mixture in the internal combustion engine. The process to start the engine by igniting an air fuel mixture introduced in the engine's combustion chamber can be continued after the power supplied to the starter is interrupted. The engine can thus be stared even after the power supplied to the starter is interrupted. Brief Description of the Drawings Fig. 1 is a block diagram of control for a vehicle including an ECU, a controller for starter in accordance with an embodiment of the present invention. Fig. 2 is a flowchart illustrating a control configuration of a program run by the Fig. 1 ECU. Fig. 3 represents how an engine's rate of rotation varies with time as a vehicle having the Fig. 1 control is started.

Best Modes for Carrying Out the Invention Hereinafter reference will be made to the drawings to describe an embodiment of the present invention. In the following description, identical components are denoted by identical reference characters and are also identical in name and function. Fig. 1 shows a block diagram of control for a vehicle including an ECU, a controller for a starter in accordance with an embodiment of the present invention. It should be noted that the present invention is not limited to a belt driven starter shown in

Fig. 1. A magnet switch, a pinion gear and/or the like, rather than the belt, may be used. Furthermore, the starter is not limited to a motor for starting an engine and may be a starter generator starting an engine and regeneratively generating power. These are referred to as an electric machine. Furthermore, the vehicle may be a vehicle mounting only an engine, or a hybrid vehicle mounting an engine and a motor generator, a motor for running the vehicle. Alternatively, the vehicle may be a vehicle automatically stopping the engine to prevent idling for example when the vehicle temporarily stops for the red light. As shown in Fig. 1, the vehicle includes an engine 100 serving as an internal combustion engine, a transmission 200 connected to an output shaft of engine 100, a starter 300 starting engine 100, a power supply 400 in the form for example of a secondary battery, a capacitor or similar electricity storage mechanism supplying the starter with power, an electronic control unit (ECU) 500 controlling starter 300, and a starter relay 350 operative in response to a command signal output from ECU 500 to supply and interrupt power provided from power supply 400 to starter 300. ECU 500 receives the engine's rate of rotation from a sensor 600 detecting the engine 100 rate of rotation, and an engine start signal based on a signal for example of an ignition switch operated by the driver of the vehicle. Furthermore, ECU 500 outputs to starter relay 350 a start command signal (to start supplying power from power supply 400 to starter 300), a stop command signal (to stop power supplied from power supply 400 to starter 300) and the like. Starter 300 has a relay 310 and a belt driven starter 320. Relay 310 has a switch terminal 360 connected to starter relay 350 and receiving power when starter relay 350 is closed. When switch terminal 360 receives power, relay 310 closes a path passing power supplied from power supply 400 to belt driven starter 320 and supplies power from power supply 400 to belt driven starter 320. Belt driven starter 320 has a shaft of rotation provided with a pulley 330 for the starter to transmit power via a belt 340 to a pulley 110 for the crank shaft of engine 100. Note that starter 300 and power supply 400 has a sufficient ability to provide cranking to reach a rate of rotation allowing engine 100 to be ignited satisfactorily for the sake of illustration. More specifically, if the power supply 400 availability, the engine 100 variation in rotation resistance and/or the like invite a varied cranking rotation rate it has a sufficiently high lower limit for the sake of illustration. Furthermore, ECU 500 has stored in memory an upper limit of the cranking rotation rate that does not affect engine 100 and transmission 200 in durability when poor lubrication is provided. Furthermore, ECU 500 also has stored in memory a lower limit of the engine's rate of rotation that allows engine 100 to be started when engine 100 is inertially rotating. During cranking when engine 100 is started (or an air fuel mixture introduced into the combustion chamber of engine 100 is ignited) ECU 500 interrupts power supplied to starter 300. It should be noted, however, that if the cranking rotation rate has reached the upper limit and engine 100 has still not been started (or ignited) ECU 500 interrupts power supplied to starter 300, While ECU 500 has thus interrupted power supplied to starter 300, ECU 500 still continues a process to ignite the air fuel mixture in the engine 100 combustion chamber. ECU 500 implements such control by a program. Reference will now be made to the Fig. 2 flowchart to describe a control configuration of the program run by ECU 500. Note that this flowchart illustrates a process performed after ECU 500 has received an engine start signal. At step(S) 100, ECU 500 outputs a start command signal to starter 300. More specifically, ECU 500 outputs the start command signal to starter relay 350, and a relay contact is turned on and power is supplied from power supply 400 via relay 310 to belt driven starter 320. At S200, ECU 500 determines whether the air fuel moisture in the combustion chamber of engine 100 has been ignited. This decision is made for example from a rapidly increased rate of rotation of engine 100 that is detected by engine rotation rate sensor 600 and/or a signal output from a separately provided temperature sensor detecting the temperature of gas exhausted from engine 100. When the air fuel mixture is ignited (YES at S200) the process ends. Otherwise (NO at SI 00) the process moves on to S300. At S300, ECU 500 detects the engine 100 rate of rotation from a signal output from sensor 600. At S400, ECU 500 determines whether the engine 100 rate of rotation attains the upper limit or more stored in the ECU 500 memory, If so (YES at S400) the process moves on to S 500. Otherwise (NO at S400) the process returns to S200. At S500, ECU 500 outputs the stop command signal to starter 300. More specifically, ECU 500 stops outputting the start command signal to starter relay 350. The relay contact is turned off to interrupt power supplied from power supply 400 via relay 310 to belt driven starter 320. At S600, ECU 500 detects the engine 100 rate of rotation from a signal output from sensor 600. At S700, ECU 500 determines whether the engine 100 rate of rotation is the lower limit or less stored in the ECU 500 memory. If so (YES at S700) the process returns to SI 00. Otherwise (NO at S700) the process moves on to S800. At S800, ECU 500 determines whether the engine 100 combustion chamber has the air fuel mixture igmted. If so (YES at S800) the process ends. Otherwise (NO at S800) the process returns to S600. In accordance with the above described configuration and flowchart engine 100 of a vehicle mounting ECU 500 corresponding to a controller for starter 300 operates when the engine starts, as will now be described hereinafter. For example when the vehicle's driver put an ignition switch at the start position, or the control to stop idling is exerted and engine 100 is temporarily stopped, while a condition for temporarily stopping the engine is not established, then ECU 500 receives an engine stop signal. ECU 500 outputs the start command signal to starter relay 350 (S100), power supply 400 supplies belt driven starter 320 with power, power is transmitted from belt driven starter 320 via starter pulley 330, belt 340 and crank shaft pulley 110, and engine 100 is cranked. If engine 100 is not ignited (NO at S200) the engine 100 rate of rotation is detected (S300). If the engine 100 rate of rotation is the upper limit or more (YES at

S400) ECU 500 outputs the stop command signal to starter relay 350 (S500) to stop power supplied from power supply 400 to belt driven starter 320. In this condition, engine 100 is inertially rotating. In this condition, the process to ignite engine 100 still continues until the engine 100 rate of rotation attains the lower limit or less (NO at S700). This condition is shown in Fig. 3. Fig. 3 represents how the engine 100 rate of rotation varies with time when the engine starts. As has been described above, the ECU 500 memory has the upper and lower limits set therein. In cranking when engine 100 ignites with a rate of rotation falling within a range lower than the upper limit (YES at S200) the rate of rotation varies, as indicated in Fig. 3 by a thick dashed line. More specifically, engine 100 ignites and starts before power supplied to starter 300 is interrupted. When engine 100 is unignited and the upper limit is reached (YES at S400) power supplied to starter 300 is interrupted (S500) and the engine 100 rate of rotation gradually decreases as indicated in Fig. 3 by a thin dashed line. Until the rate of rotation drops to the lower limit or less (NO at S700) the engine 100 ignition process continues and, as indicated in Fig. 3 by a thick solid line, engine 100 ignites as it inertially rotates (YES at S800). Note that in Fig. 3 an alternate long and short dashed line indicates how the engine 100 rate of rotation varies when the rate of rotation attains the upper limit or more and power supplied to starter 300 is nonetheless not interrupted. Thus the present starter controller interrupts power supplied to the starter in cranking when the engine starts (or an air fuel mixture introduced into the engine's combustion chamber ignites). If the engine's rate of rotation has reached an upper limit of a cranking rotation rate and despite that the engine is unstarted (or unignited) then power supplied to the starter is interrupted. While the power supplied to the starter is thus interrupted, the process to ignite the air fuel mixture in the engine's combustion chamber still continues. If the power supplied to the starter is interrupted, the engine will not immediately stop and continue to rotate inertially, when the ignition process can be performed to start the engine. This can prevent an excessively increased rate of rotation of the engine attributed to cranking that results in a problem in durability of the engine, transmission and the like. Furthermore, reduced starter energization time can be achieved, and this provides increased life of a sliding portion of a motor brush or the like of the starter, prevents a temporarily reduced output attributed to the starter's self heat generation, and contributes to conserved power. Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.

Claims

1. Controller controlling an electric machine (300) operated to start an internal combustion engine (100), said electric machine (300) receiving power from an electricity storage mechanism (400), comprising: detection means (600) for detecting a rate of rotation of said internal combustion engine (100); start detection means (500) for detecting that said internal combustion engine (100) has started; and control means (500) for interrupting power supplied to said electric machine

(300) and also continuing a process for starting said internal combustion engine (100) when said electric machine (300) cranks said internal combustion engine (100) and said internal combustion engine (100) attains at least a predetermined rate of rotation, and said start detection means nevertheless does not detect that said internal combustion engine ( 100) has started.

2. The controller of claim 1, wherein said control means (500) includes means for control to continue said process for starting said internal combustion engine (100) when said electric machine (300) is interrupted from receiving power and said internal combustion engine (100) is nevertheless inertially rotating.

3. The controller of claim 2, wherein said control means (500) includes means for control to continue said process for starting said internal combustion engine (100) when said internal combustion engine (100) is inertially rotating at at least a predetermined rate of rotation.

4. The controller of any of claims 1-3, wherein said process for starting said internal combustion engine (100) is a process for igniting an air fuel mixture in said internal combustion engine (100).

5. A controller controlling an electric machine (300) operated to start an internal combustion engine (100), said electric machine (300) receiving power from an electricity storage mechanism (400), comprising: a sensor (600) detecting a rate of rotation of said internal combustion engine(lOO); and an electronic control unit (500) exerting control to interrupt power supplied to said electric machine (300) and also continue a process for starting said internal combustion engine (100) when said electric machine (300) cranks said internal combustion engine (100) and said internal combustion engine (100) attains at least a predetermined rate of rotation, and that said internal combustion engine (100) has started is nevertheless not detect.

6. The controller of claim 5, wherein said electronic control unit (500) exerts control to continue said process for starting said internal combustion engine (100) when said electric machine (300) is interrupted from receiving power and said internal combustion engine (100) is nevertheless inertially rotating.

7. The controller of claim 6, wherein said electronic control unit (500) exerts control to continue said process for starting said internal combustion engine (100) when said internal combustion engine (100) is inertially rotating at at least a predetermined rate of rotation.

8. The controller of any of claims 5-7, wherein said process for starting said internal combustion engine (100) is a process for igniting an air fuel mixture in said internal combustion engine (100).