FR2849118A1 - Starter for IC engine of vehicle, has electronic control unit reducing field current of electric motor on identifying that catalytic converter is in inactive state - Google Patents

Abstract

The device has a starter (1) with an electronic control unit (2) that evaluates whether a catalytic converter is in inactive or active state before purifying an exhaust gas in a motor, at the time of starting the motor. The electronic control unit reduces field current of the electric motor through activation circuit (5) to start the motor in a high rate, if the converter is in an inactive state.

Description

ENGINE STARTING DEVICE

  Field of the Invention The present invention relates to an engine starting device intended to start an engine at high speed (revolutions per minute) when a catalytic converter is in an inactive state. BACKGROUND OF THE INVENTION Traditionally, DC motors with series windings, in which a field winding is connected in series with an armature winding, have often been used as electric starter motors in starting devices motor (refer to unexamined Japanese patent publication N 2000-125 579) The output of this type of direct current motor is determined on the basis of the motor launch torque, the lowest rotation speed allowing start the engine etc, so that a sufficient rotation speed can be obtained even in winter (in extremely low temperature conditions).

  However, when the engine is started by the DC motor, when the engine starting speed (starting speed) is low, and the pressure of the intake air which is drawn into the cylinder is therefore low, the fuel is not sufficiently atomized and the quantity of fuel remaining in the intake port increases. Furthermore, at low engine speed, the cylinder pressure is low even when it is compressed by the piston, and the quantity fuel which is not sprayed remaining in the cylinder also increases.

  As the engine speed increases after that, some of the remaining fuel is used for combustion, but as the air / fuel ratio becomes rich, most of the remaining fuel escapes as unburned gas In particular, when A catalytic converter is in an inactive state, for example when the engine is started from a cold state, the remaining fuel can be emitted directly into the atmosphere because the purification performance of the catalytic converter is poor.

  A first possible approach to reducing the amount of fuel remaining would be to reduce the amount of fuel injection, but the amount of fuel remaining is difficult to predict. For this reason, if the amount of fuel injection is simply reduced, the engine start performance may drop, depending on fuel properties.

  The present invention has been devised in view of the above situation and an object of the invention is to provide an engine starting device which can reduce the emissions (HC) emitted into the atmosphere, even when the catalytic converter is in an inactive state. SUMMARY OF THE INVENTION (First aspect of the invention) An engine starting device using at least one starter in accordance with a first aspect of the invention comprises a catalytic converter condition evaluation means intended to evaluate whether a catalytic converter to purify an exhaust gas in the engine is in an inactive state or not and, when the engine is starting, if the catalytic converter is estimated to be in an inactive state, the engine is started at an higher speed than when the catalytic converter 20 is in an active state.

  When the catalytic converter is in an inactive state, if the engine is started at high speed, the engine speed increases compared to that of the normal state (i.e., when the catalytic converter is in the active state), the result is that the amount of fuel remaining in the intake port and the cylinder decreases, and the injected fuel contributes correctly to combustion Consequently, even when the catalytic converter is in an inactive state, the emissions (HC) emitted into the atmosphere can be reduced. 30 (Second aspect of the invention).

  An engine starting device according to a second aspect of the invention comprises a first starter having a power characteristic of the high torque type and a second starter having a power characteristic of the high speed type and when starting the engine , if the catalytic converter is estimated to be in an inactive state, the engine is started using the second starter.

  When the catalytic converter is in an inactive state, if the engine is started at high speed using the second starter, the engine speed increases compared to that of the normal state (i.e. when the pot catalytic is in an active state) As a result, the amount of fuel remaining in the intake port and the cylinder decreases, and the correctly injected fuel contributes to combustion. Consequently, even when the catalytic converter is in an inactive state. , emissions to the atmosphere can be reduced. (Third aspect of the invention) In the engine starting device, the state evaluation means 10 of the catalytic converter evaluates that the catalytic converter is in an inactive state when the temperature of the catalytic converter is lower than a predetermined temperature. .

  In this case, the catalytic converter can be reliably estimated to be in an inactive state since the state of the catalytic converter (active state / inactive state) is evaluated on the basis of the temperature of the catalytic converter itself. Consequently, when the temperature of the catalytic converter is lower than the predetermined temperature, it is estimated that the catalytic converter is in an inactive state, and the emissions can be reduced by starting the engine at a higher speed than when the catalytic converter is in an active state.

  (Fourth aspect of the invention) In the engine starting device, the state evaluation means of the catalytic converter estimates that the catalytic converter is in an inactive state when the oil temperature or the temperature of the The engine coolant is lower than a first predetermined temperature.

  When the oil temperature or the engine coolant temperature is low (lower than the first predetermined temperature), it is estimated that the temperature of the catalytic converter is also low Therefore, in this case, the catalytic converter is believed to be in an inactive state, and emissions can be reduced by starting the engine at a higher speed than when the catalytic converter 35 is in an active state.

  (Fifth aspect of the invention) In the engine starting device, the state evaluation means of the catalytic converter estimates that the catalytic converter is in an inactive state when the engine has been in a stopped state for more of a predetermined time interval. When the time elapsed since the time when the engine was last stopped is long (longer than a predetermined time interval), the temperature of the catalytic converter is considered to be low Therefore, in this case, the catalytic converter is believed to be in an inactive state, and emissions can be reduced by starting the engine at a higher speed than when the catalytic converter is in an active state.

  (Sixth aspect of the invention) The engine starting device is used in an automatic engine stop / start system which automatically controls the stopping and restarting of the engine, and its means for evaluating the state of the engine. catalytic converter considers that the catalytic converter is in an inactive state when the engine is started by actuating an ignition key, but not when the engine is restarted by the automatic engine start / stop system.

  In the system which automatically controls the stopping and restarting of the engine, it is estimated that the catalytic converter is in an active state when the engine is restarted (thanks to an automatic control) On the other hand, when the driver starts the engine by actuating the ignition key, it is estimated that the catalytic converter is in an inactive state For this reason, in this case (when the engine is started by actuating the ignition key), it is estimated that the catalytic converter is in an inactive state, and emissions can be reduced by driving the engine at a higher speed than when the catalytic converter is in an active state.

  (Seventh aspect of the invention) The engine starting device comprises an electric motor control means for controlling an output characteristic of an electric motor provided in the starter, and the electric motor control means changes the power characteristic of the electric motor in a high speed type, thus allowing the motor to be driven at high speed.

  When the engine is driven at high speed by changing the power characteristic (torque-rotational speed) of the engine to a high speed type, the engine speed increases compared to that of the normal state, and therefore the emissions can be reduced.

  (Eighth aspect of the invention) In the motor starting device, the electric motor control means controls the power characteristic of the electric motor into a high speed type by varying the field current of the motor.

  Since the power characteristic of the electric motor 10 can be controlled on the basis of the field current of the electric motor, the motor can be started at high speed by executing a command to vary the field current, thereby toggling the power characteristic of the electric motor into the high speed type. (Ninth aspect of the invention) In the motor starting device, the electric motor has a series winding and a parallel winding, and the electric motor control means includes an activation circuit which can activate the parallel winding 20 such that the field current flowing in the parallel winding is in the opposite direction to the field current flowing in the series winding, where the motor control means reduces the field current of the electric motor by controlling by means of the circuit at least either the intensity of the current or the direction of the current flowing in the parallel winding.

  If the field current of the parallel winding is reduced, a sufficiently high engine speed may not be obtained due to the influence of the magnetic flux produced in the series winding In this case, by activating the parallel winding in such a way that the field current flowing in the parallel winding is in the opposite direction to the field current flowing in the series winding, the influence of the magnetic flux produced in the series winding can be canceled, and a speed of Sufficiently high motor can be obtained As a result, the motor can be driven at high speed.

  (Tenth aspect of the invention) In the motor starting device, the motor control means comprises a 40 field current reduction means making it possible to reduce the field current flowing in a field winding (series winding) of the field. motor, and the motor control means reduces the field current of the electric motor using the field current reduction means. By using the field current reduction means to reduce the field current flowing in the field winding (series winding) of the electric motor, the power characteristic of the motor can be controlled in the high speed type, so that the engine can be started at high speed.

  (Eleventh aspect of the invention) In the engine starting device, the electric motor control means reduces the field current of the electric motor in accordance with the speed of the motor or the starter.

  When the field current is controlled in accordance with the engine or starter speed, the motor can be properly driven at high speed.

  (Twelfth aspect of the invention) In the engine starting device, the electric motor control means reduces the field current of the electric motor in accordance with a position of the crankshaft in the engine. When the field current is controlled in accordance with the position of the engine crankshaft, the engine 25 can be driven more correctly at the speed by reducing the effects of variations in torque / rotational speed associated with the intake-compression-explosion-exhaust times of the piston.

  (Thirteenth aspect of the invention) In the engine starting device, the electric motor control means reduces the field current of the electric motor after a piston reaches a top dead center in any of the cylinders after the engine start.

  After starting the engine, air at substantially atmospheric pressure continues to be compressed in the engine 35 until after a piston has reached top dead center in any of the cylinders Therefore during this period , significant torque is required to start the engine.

  However, once a piston reaches top dead center in any of the cylinders, the engine itself generates a driving force due to the explosion that follows compression, and the significant torque to drive the engine is no longer needed In view of this, before a piston reaches top dead center in any of the cylinders, an increase in the field current changes the power characteristic of the starter to the high torque type , and then, after a piston has reached top dead center in any of the cylinders, a reduction in the field current changes the power characteristic of the starter to the high speed type so that the engine can be properly trained at high speed.

  (Fourteenth aspect of the invention) In the motor starting device, the electric motor control means establishes an electric current value which maximizes the power of the electric motor as a control target value for the field current.

  If the power of the electric motor can be maximized by controlling the field current, the motor can be started at maximum speed, and therefore the emission reduction effect can be maximized.

  (Fifteenth aspect of the invention) In the engine starting device according to any of the eighth to fourteenth aspects, the electric motor control means stops the field current reduction control when the temperature of the oil or the temperature of the engine coolant is lower than a second predetermined temperature which is lower than the first predetermined temperature in order to assess whether the catalytic converter is in an inactive state or not.

  At extremely low temperatures, the viscosity of the engine oil increases, and a higher engine drive torque may be required when starting the engine. Consequently, when the oil temperature or the engine temperature motor coolant is lower than the predetermined temperature (second predetermined temperature) below which a higher motor drive torque is required, the field current reduction control is stopped, and the electric motor is driven with a characteristic of the high torque type so that the engine can be started correctly even 40 at extremely low temperatures.

  (Sixteenth aspect of the invention) In the engine starting device, the engine control means stops reducing the field current when the oil temperature or the engine coolant temperature is higher. high than a third predetermined temperature which is higher than the first predetermined temperature, to assess whether the catalytic converter is in an inactive state or not.

  Under high temperature conditions, for example when the engine is stopped after driving with a heavy load such as uphill driving, and the engine is restarted immediately after that, the cylinder is more tight, which requires a higher engine driving torque when starting the engine Consequently, when the oil temperature or the engine coolant temperature is higher than the predetermined temperature (third predetermined temperature) above which the higher motor drive torque is required, it is stopped to reduce the field current and the electric motor is driven with a characteristic of the high torque type, so that the motor can be started correctly even at extremely high temperatures.

  (Seventeenth aspect of the invention) In the engine starting device, the electric motor control means stops reducing the field current when the engine or starter speed has failed to reach a speed. predetermined.

  When the motor is driven at high speed by reducing the field current of the electric motor, if the engine speed 30 does not rise for any reason, the reduction of the field current is stopped, and the electric motor is driven with a characteristic of the high torque type so that the engine can be started correctly even in an abnormal condition.

  (Eighteenth aspect of the invention) In the engine starting device, the electric motor control means stops reducing the field current when the battery is at a low state of charge.

  When the battery and at a low state of charge, for example when the vehicle has been left for an extended period of time, the power of the starter drops Consequently, when the battery is at low state of charge the field current does not is not reduced, and the electric motor is driven with a characteristic of the high torque type so that the motor can be driven correctly.

  (Nineteenth aspect of the invention) In the motor starting device, a supply means for supplying a field current to the parallel winding is provided separately from a battery, and the motor control means electric stops reducing the field current when the supply means is at a charging stage below a predetermined level.

  A separate power supply (e.g. a capacitor) may be provided to activate the field winding (parallel winding) so as to prevent the battery voltage from falling due to a large current flow to the electric motor when the electric motor field current control In this case, if the separate supply (supply means) is at a state of charge lower than that of the predetermined battery charge level, the magnetic field 20 necessary for the drive engine cannot be worked out.

  In this case, the field current for the parallel winding is not reduced so that the motor can be driven correctly. (Twentieth aspect of the invention) In the engine starting device, the electric motor provided in the starter is a direct current motor. By using a DC motor, the system of the present invention can be realized in a simple manner and at low cost.

  (Twenty-first aspect of the invention) In the engine starting device, the engine is started using the first starter when the oil temperature or the engine coolant temperature is higher. lower than a second predetermined temperature, which is lower than the first predetermined temperature for evaluating whether the catalytic converter is in an inactive state or not. At extremely low temperatures, the viscosity of the engine oil increases, and a higher engine drive torque may be required when starting the engine. Consequently, when the oil temperature or the engine temperature engine coolant is lower than the predetermined temperature (second predetermined temperature) below which a higher engine drive torque is required, the second starter having the power characteristic of the high speed type n ' is not used, but the first starter having the power characteristic of the high torque type is triggered to start the engine. By doing this, the engine can be started correctly even at extremely low temperatures.

  (Twenty-second aspect of the invention) In the engine starting device, the engine is started using the first starter when the oil temperature or the engine coolant temperature is higher than a third predetermined temperature which is higher than the first predetermined temperature for evaluating whether the catalytic converter is in an inactive state or not.

  In high temperature conditions, for example when the engine is stopped after driving with a heavy load such as uphill driving, and the engine is restarted immediately, the cylinder is more tight, which imposes a driving torque of the engine higher when starting the engine Consequently, when the oil temperature or the engine coolant temperature is higher than the predetermined temperature (third predetermined temperature) above which a torque of higher motor drive is required, the second starter having the power characteristic of the high speed type is not used, but the first starter having the power characteristic of the high torque type is triggered to start the engine By doing this, the engine can be started correctly even at extremely low temperatures. (Twenty-third aspect of the invention) In the engine starting device, when the engine has been started using the second starter, if the engine speed or the second starter has failed to reach a predetermined speed , the engine is started by switching from the second starter to the first starter.

  When the engine is started using the second starter having the power characteristic of the high speed type, if the engine rotational speed does not go up due to some failure, the second starter is stopped, and the first starter having the power characteristic of the high torque type is triggered to start the engine. By doing this, the engine can be started correctly even in a faulty state.

  (Twenty-fourth aspect of the invention) In the engine starting device, the engine is started using the first starter when a battery is at a low charge stage.

  When the state of charge of the battery is at a low charge stage, for example when the vehicle has been left for an extended period of time, the second starter having the power characteristic of the high speed type is not used, but the first starter having the power characteristic of the high torque type is triggered to start the engine. By doing this, the engine can be started correctly.

  (Twenty-fifth aspect of the invention) In the engine starting device, when the engine speed is higher than a predetermined speed, the amount of fuel injection is reduced compared to a case where the pot catalytic is in an active state.

  When the engine speed is higher than the predetermined speed, the air / fuel ratio for combustion becomes rich, since the amount of fuel remaining in the intake port and the cylinder decreases As a result, if the same amount of fuel than that in the case of a normal engine start (engine start when the catalytic converter is in an active state) is injected, unburned gas will be emitted Consequently, by reducing the amount of fuel injection compared to that in the normal case, the amount of unburned gas emitted can be reduced, and emissions can therefore be reduced.

  (Twenty-sixth aspect of the invention) In the engine starting device, when the engine speed is higher than the predetermined speed, the amount of fuel injection is reduced according to the air / fuel ratio. By reducing the amount of fuel injection according to the air / fuel ratio, emissions can be further reduced. (Twenty-seventh aspect of the invention) In the engine starting device, a fuel injection is started after it is detected that the pressure of the intake manifold in the engine is less than a predetermined value.

  If the engine intake manifold pressure is high, the fuel is not atomized sufficiently and the air / fuel mixture in the intake port cannot be correctly introduced into the cylinder. For this reason, launching the Fuel injection after detecting that the engine intake manifold pressure is lower than the predetermined value, the amount of unburned gas in the intake port can be reduced, which helps to reduce emissions.

  (Twenty-eighth aspect of the invention) In the engine starting device, the fuel injection is started after it is detected that the engine rotation speed is higher than a predetermined speed.

  If the engine speed is higher than the predetermined speed, the air / fuel mixture of the intake light can be introduced correctly into the cylinder, and the emissions can therefore be reduced.

  (Twenty-ninth aspect of the invention) In the engine starting device, fuel injection is started after it is detected that the total engine speed counted since the engine started has reached a value predetermined.

  If the total engine speed counted since the engine was started is greater than the predetermined value, it is expected that the intake manifold pressure will be sufficiently low. As a result, the air / fuel mixture of the intake light can be introduced correctly into the cylinder, and emissions can therefore be reduced. i

  (Thirtieth aspect of the invention) In the engine starting device, the injection of fuel is started after it is detected that a predetermined time has elapsed since the engine started.

  If the predetermined time has elapsed since the engine started, it is expected that the intake manifold pressure is low enough For this reason, the air / fuel mixture in the intake port can be introduced correctly in the cylinder, and emissions 10 can therefore be reduced. (Thirty-first aspect of the invention) In the starting device

  engine, when starting the engine by driving the engine at high speed, a threshold speed for perfect combustion is changed in accordance with an engine speed.

  When the engine is started at high speed, the engine can continue to be driven beyond the threshold speed for perfect combustion which is used in a normal engine start (engine start when the catalytic converter is in an active state) In view of this, when starting the engine by driving it at a high speed, the threshold speed for perfect combustion is modified in accordance with the engine speed. This ensures correct starting of the engine.

  (Thirty-second aspect of the invention) In the engine starting device, when the engine speed has reached the threshold speed for perfect combustion, the operation of the starter is stopped.

  In the case of a system which automatically starts the starter of the present invention, the engine can be started correctly if the starter drive is stopped when the engine speed has reached the threshold speed for perfect combustion.

  Other characteristics and advantages will be highlighted in the presentation of the embodiments, in relation to the following drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

  Figure 1 is an electrical circuit diagram of an engine starting device.

  FIG. 2 is a diagram representing characteristics 40 of power of the starter.

  FIG. 3 is a flow diagram illustrating the operation of the engine starting device (first embodiment). Figure 4 is a timing diagram for explaining the operation and effect (reduction of HC hydrocarbons) of the embodiment.

  Figure 5 is a flowchart illustrating the operation of the engine starting device (second embodiment). Figure 6 is a flowchart illustrating the operation of the engine starting device (third embodiment). Figure 7 is an electrical circuit diagram of an engine starting device (third embodiment).

  Figure 8 is an electrical circuit diagram of an engine starting device (fourth embodiment). Embodiments of the Invention Embodiments of the present invention will be described below with reference to the drawings.

  (Embodiment 1) Figure 1 is an electrical circuit diagram of an engine starting device.

  The engine starting device A of this embodiment is used in what is called the idling stop system which automatically stops the engine when the vehicle comes to a stop, for example at a crossroads or in a traffic jam, and restarts the engine (not shown) when a prescribed starting condition is satisfied (for example when the driver releases the brake pedal and presses the accelerator pedal) The engine starting device is equipped with a starter 1 for starting the engine and is controlled by an electronic control unit (ECU) 2 (which contains engine control means of the present invention). The starter comprises a direct current motor with compound winding, the rotary output of which is transmitted to the motor to start the motor. The starter 1 can be of the type driven by a pinion which brings the pinion up to meshing with the crown of the motor, or of the belt drive type which transmits the power from starter 1 to the motor by means of a drive belt.

  The DC motor has a series winding 4 5 connected in series with an armature 3, and a parallel winding 6 connected to an activation circuit 5 described below, and is activated by being connected to a vehicle battery 10 by via a starter relay 8 and an electromagnetic switch 9 when an ignition key switch 7 10 is closed (in position ST).

  The activation circuit 5 comprises four control elements 11 (for example MOS type field effect transistors (MOS-FET)) connected in bridge, an input terminal 5a of which is connected to the positive terminal of the vehicle battery 10 via the electromagnetic switch 9, and the other input terminal 5 of which is grounded.

  The ECU 2 controls the field current flowing in the parallel winding 6 by controlling the activation circuit 5 More specifically, the ECU 2 controls the intensity and the direction of the current flowing in the parallel winding 6 (the current can be caused to flow in the opposite direction to the direction of the current in the series winding 4) in accordance with the duty cycle of each control element 11 in the activation circuit 5 As a result, as indicated in FIG. 2 , The power characteristic of the DC motor becomes of the high speed type when the field current decreases, and of the high torque type when the field current increases. Next, the operation of the engine starting device A is described with reference to the flow diagram shown in FIG. 3.

  Step 10: the presence or absence of a start request is checked Here, when a restart request is detected after an automatic engine stop, it is decided that a start request has occurred If the result of the decision is YES, the processing proceeds to the next step 20, but if the result of the decision is NO, the processing is stopped. Step 20: a decision is made as to whether the catalytic converter 40 intended for purifying the exhaust gas is in an inactive state or not The inactive state of the catalytic converter is detected on the basis of the following criteria.

  a) The temperature of the catalytic converter is lower than a predetermined temperature (for example 300 C).

  b) The oil temperature or the engine coolant temperature is lower than a first predetermined temperature (for example 60 C).

  c) The engine has been in a stopped state for more than a predetermined time interval (eg 10 minutes).

  If the result of the decision is NO, the processing proceeds to the next step 30, but if the result of the decision is YES, the processing proceeds to step 60.

  Step 30: the duty cycle of each control element 11 in the activation circuit 5 is controlled (increased) so as to increase the field current flowing in the parallel winding 6.

  Step 40: the starter 1 is activated.

  Step 50: after the execution of a normal motor command, the processing goes to step 140.

  Step 60: the duty cycle of each control element 11 in the activation circuit 5 is controlled (increased) so as to increase the field current flowing in the parallel winding 6.

  Step 70: the starter 1 is activated.

  Step 80: a decision is made as to whether the top dead center is detected in any of the cylinders If the top dead center is detected (the result of the decision is YES), the processing goes to step 90.

  Step 90: the duty cycle of each control element 30 11 in the activation circuit 5 is controlled (decreased) so as to reduce the field current flowing in the parallel winding 6 In this case, the duty cycle of each element The control element 11 can be gradually reduced so as to prevent a shock which can be caused by a sudden variation in the power characteristic of the starter 1.

  Step 100: a decision is made as to whether the engine speed has exceeded a predetermined speed N In this case, the fact that the engine speed has increased to the speed at which a fuel injection can be started is determined by referring to the predetermined speed N When the engine speed has exceeded the predetermined speed N (the result of the decision is YES), the processing goes to step 110.

  Step 110: the amount of fuel injection is reduced compared to that of a normal engine control.

  More specifically, the amount of fuel injection is determined from the current engine speed by referring to a map In step 110, the amount of fuel injection can be controlled based on the air / fuel ratio .

  Step 120: the injection of fuel into the engine is started. Step 130: the threshold speed S for perfect combustion is determined according to the current engine speed by referring to a map.

  Step 140: the decision step 140 is repeated until the current engine speed exceeds the threshold speed S for perfect combustion, determined in step 130 When the threshold speed S for perfect combustion is exceeded (the result of the decision is YES), the processing goes to step 20 150.

  Step 150: the starter 1 is deactivated, after which the processing is stopped.

  (Effect on Embodiment 1) According to this embodiment, when the catalytic converter is in an inactive state, first of all, the engine is driven by controlling the power characteristic of starter 1 to the high torque type (increasing the field current), as shown in Figure 4 (a), and then, after top dead center is reached in any of the 30 cylinders, the power characteristic of starter 1 is controlled to the type at high speed by reducing the field current of the electric motor, thus making it possible to operate the motor correctly at high speed. As a result, the speed of the motor during launch increases compared to the normal case (the case where the pot catalytic is in the active state), as shown in Figure 4 (b), the amount of fuel remaining in the intake port and the cylinder decreases, and the injected fuel contributes correctly to the As a result, even when the catalytic converter is 40 in the inactive state (the purification performance is poor), emissions (HC) emitted into the atmosphere can be reduced (see Figure 4 (c)) .

  In addition, when the engine speed is higher than the predetermined speed N, the air / fuel ratio for combustion becomes rich, since the amount of fuel remaining in the intake port and the cylinder decreases As a result, if the same amount of fuel as in the case of normal engine starting (starting the engine when the catalytic converter is in an active state) is injected, unburned gas will be emitted Consequently, by reducing the amount of fuel injection compared to normal engine control, the amount of unburned gas emitted can be reduced, which further reduces emissions.

  The first embodiment has been described by assuming a case where the engine is restarted after an automatic stop but, even when the engine is started by activation of the starter 1 by actuation of the ignition key 7, the same effect as that obtained in the first embodiment can be obtained by reducing the field current of the electric motor and therefore by driving the motor at a high speed when the catalytic converter is estimated to be in an inactive state In this case, outside the criteria previously provided a) to c) intended to evaluate the inactive state of the catalytic converter, it can be estimated that the catalytic converter is in an inactive state when the engine 25 is started by actuating the ignition key 7.

  (Embodiment 2) Figure 5 is a flowchart illustrating the operation of the engine starting device A. In this embodiment, steps 80/90 and 100 A are performed in place of steps 80 through 100 shown in the flowchart described in the first embodiment Furthermore, the processing (steps 10 to 70 and 110 to 150) is the same as that of the first embodiment (the description will not be repeated here).

  The details of steps 80/90 and 100 A will be described below. Step 80/90: the field current of the electric motor is reduced compared to the normal case (the case where the catalytic converter is in a normal state) More particularly, the field current is determined according to the current engine speed or the starter speed by referring to a map.

  Step 100 A: a decision is made as to whether the pressure of the intake manifold is either equal to or greater than a predetermined value p If the pressure of the intake manifold is higher than the predetermined value p (the result of the decision is NO), processing returns to step 80/90, but if the intake manifold pressure is not higher than the predetermined value p (the result of the decision is 10 YES), processing proceeds to step 110.

  According to the present embodiment, when the field current is reduced according to the engine or starter speed, the engine can be started correctly at high speed.

  In addition, since fuel injection begins after detecting that the engine intake manifold pressure is not higher than the predetermined value p, the air / fuel mixture in the intake port can be introduced correctly in the cylinder, which reduces the amount of unburned gas in the intake port This helps to reduce emissions more reliably.

  In the present embodiment, a decision is made in step 100 OA as to whether the pressure of the intake manifold is not higher than the predetermined value p, but instead, one can take a decision as to whether the total number of revolutions counted since the engine started has reached a predetermined value in order to be able to initiate fuel injection, after the predetermined value has been reached Alternatively, a decision may be taken as to whether a predetermined time has elapsed since the engine started so as to initiate fuel injection after the predetermined time has elapsed.

  In these cases, when it is judged that the pressure of the intake manifold is sufficiently low, the air / fuel mixture in the intake port can be introduced correctly into the cylinder, and therefore the emissions can be reduced.

  (Embodiment 3) Figure 6 is a flowchart illustrating the operation 40 of the motor starting device A This embodiment relates to an example in which the command for the reduction of the field current is stopped, and is changed to the command normal engine.

  The details of the order in accordance with this embodiment will be described below with reference to the organization chart.

  Steps 10 to 70: identical to the corresponding steps of the first embodiment (refer to the description of the first embodiment).

  Step 80: the field current of the electric motor is reduced compared to that of the normal state (i.e. when the catalytic converter is in an active state) More particularly, the field current is determined d 'after the current engine speed or starter speed by referring to a map.

  Step 90: the state of charge of the battery 10 is checked.

  If the state of charge is low (the result of the decision is NO), the command to reduce the field current is stopped, and the processing goes to step 30 to switch to normal motor control If the state load is high (the result of the decision is YES), the processing proceeds to the next step 100.

  Step 100: a decision is made as to whether the engine coolant temperature (or oil temperature) is within a range which is not less than a second temperature predetermined T 1 (for example -10 C) and is not higher than a third predetermined temperature T 2 (for example 100 C) If the result of the decision is NO, that is to say if the temperature is lower at the second predetermined temperature T 1 or 30 higher than the third predetermined temperature T 2, the field current reduction command is stopped, and the processing proceeds to step 30, to switch to normal motor control If the result of the decision is YES, processing proceeds to the next step 110.

  Step 110: a decision is made as to whether the engine speed or the starter speed is lower than a predetermined speed M If the result of the decision is YES, the command to reduce the field current is stopped, and the processing goes to step 30 to switch to normal control of f. engine If the result of the decision is NO, processing proceeds to the next step 120.

  Steps 120 to 170: identical to steps 100 to 150 in the first embodiment (or steps 100 A to 150 in the second embodiment) (reference will be made to the description of the first embodiment).

  The present embodiment, when any of the following conditions a) to d) is satisfied, stops reducing the field current, and switches to normal motor control so that the motor can be started correctly . a) The battery 10 is at a low charge state.

  When the battery 10 is at a low state of charge, for example when the vehicle has been left for an extended period of time, the power of the starter 1 drops Consequently, when the battery 10 is at a low state of charge, the field current is not reduced, and the electric motor is driven with a characteristic of the high torque type so that the motor can be started correctly.

  b) The temperature of the engine coolant is lower than the second predetermined temperature T 1.

  At extremely low temperatures, the viscosity of the engine oil increases, which imposes a higher starting torque of the engine when starting the engine. Consequently, when the temperature of the coolant or the temperature of the motor oil is lower than the second predetermined temperature T 1, below which a higher motor driving torque is required, the field current is not reduced, and the motor is driven with a characteristic of the high torque type so that the motor can be driven properly even at extremely low temperatures.

  c) The temperature of the engine coolant 35 is higher than the third predetermined temperature T 2.

  In high temperature conditions such as when the engine is stopped after driving with a heavy load, for example hill driving, and the engine is immediately restarted, the cylinder is more tight, which imposes a higher torque engine drive when starting the engine As a result, when the coolant temperature or engine oil temperature is higher than the third predetermined temperature T 2 above which a higher torque motor drive is required, the field current is not reduced, and the electric motor is driven with a high torque type characteristic so that the motor can be driven properly even at extremely high temperatures .

  d) The engine speed is lower than the predetermined speed M 10.

  When the motor is driven at high speed by reducing the field current of the electric motor, if the motor speed does not rise (remains below the predetermined speed M) due to a certain failure, the field current is not 15 reduced, and the electric motor is driven with a characteristic of the high torque type so that the motor can be driven correctly even in a defective state. In the electrical circuit diagram represented in FIG. 1, the battery voltage is applied to the activation circuit 5 which controls the field current of the parallel winding 6, but as a variant, as indicated in FIG. 7, a separate power supply 12 (power supply means of the present invention) intended to activate the parallel winding 6 can be used This has the advantage of making it possible to prevent the battery voltage from falling due to a current flow important towards the armature 3 when controlling the field current of the parallel winding 6.

  When the separate power supply 12 (for example a capacitor) is used, if the state of charge of the separate power supply 12 is lower than the required level, the magnetic field necessary to drive the electric motor cannot be developed. In this case, the field current reduction control is stopped, and the electric motor is driven with a characteristic of the high torque type so that the motor can be driven correctly even in a faulty state.

  (Embodiment 4) This embodiment relates to an example in which the field current is controlled in a series winding motor which does not have a parallel winding.

  FIG. 8 is an electrical circuit diagram of a motor starting device B. In the motor starting device B of this embodiment, the electric motor comprises two sets of field windings 4 (series windings), and a normally closed relay 10 13 (means for reducing the field current of the present invention) is provided between the armature 3 and a set of field windings 4 a.

  In this case, when a switch 13b of the normally closed relay 13 is in the closed state, both the field windings 15a 4a and 4b are activated, so that the field current increases and the motor can be driven with a high torque On the other hand, when the switch 13 b is opened by activating a winding 13 a of the normally closed relay 13 under the control of the ECU unit 2, the field current flows 20 only in the other set field windings 14 b As a result, the field current decreases in comparison with the case where the switch 13 b is closed, and the motor can therefore be driven at high speed.

  The engine starting device B of this embodiment provides the same effect as that obtained in the first to third embodiments, i.e. the emissions (HC) can be reduced by reducing the current of field of the electric motor and driving the motor at high speed when the catalytic converter is in an inactive state. The first to fourth embodiments have each dealt with the configuration in which the power characteristic of the single starter 1 is caused to vary, but alternatively, two starters can be used, the first starter having a power characteristic of the high torque type and the second starter having a power characteristic of the high speed type In this case, using the second starter when the catalytic converter is in an inactive state, the engine can be started with a high speed , as 40 in the first to fourth embodiments In addition, when any of the conditions for stopping reducing the field current described in the third embodiment is satisfied, the second starter is stopped and the first starter is tripped to start the high torque engine This ensures reliable engine operation.

Claims (19)

  1 engine starting device for starting an engine using at least one starter, comprising means for evaluating the condition of the catalytic converter, intended for evaluating whether a catalytic converter intended for purifying an exhaust gas in the engine is in an inactive state or not, in which when starting the engine, if the catalytic converter is estimated to be in an inactive state, the engine is started at high speed, compared to the engine speed when the catalytic converter is in a state active.   2 An engine starting device according to claim 15 1, comprising a first starter having a power characteristic of the high torque type and a second starter having a power characteristic of the high speed type, wherein the engine is started at high speed using the second starter.   3. An engine starting device according to claim 1, in which said means for evaluating the state of the catalytic converter estimates that the catalytic converter is in an inactive state when the temperature of the catalytic converter is lower than a predetermined temperature. 4 engine starting device according to claim 30 1, wherein said state evaluation means of the catalytic converter considers that the catalytic converter is in an inactive state when the oil temperature or the temperature of the agent engine cooling is lower than a first predetermined temperature.   An engine starting device according to claim 1, wherein said means for evaluating the state of the catalytic converter considers 40 that the catalytic converter is in an inactive state when the engine has been in a stopped state for more than an interval of predetermined time.   6 engine starting device according to claim 5 1, wherein the engine starting device is used in an automatic engine start / stop system which automatically controls the stopping and restarting of said engine, and wherein said means evaluation of the catalytic converter condition estimates 10 that the catalytic converter is in an inactive state when the engine is started by actuating an ignition key but not when the engine is restarted by the automatic engine start / stop system .   7. An engine starting device according to claim 1, further comprising an electric motor control means intended to control a power characteristic of an electric motor provided in said starter, and in which the electric motor control means controls the The power characteristic of the electric motor is of a high speed type, thus allowing the motor to be started at high speed.   8 A motor starting device according to claim 25 7, wherein said electric motor control means controls the power characteristic of the electric motor to the high speed type by reducing the field current of the electric motor. 9 Motor starting device according to claim 8, wherein said electric motor comprises a series winding and a parallel winding, and said electric motor control means comprises an activation circuit which activates the parallel winding of in such a way that the field current flowing in the parallel winding is in the opposite direction to the field current flowing in the series winding, and the electric motor control means reduces the field current of the electric motor by controlling, by via the activation circuit, at least either the intensity of the current or the direction of the current flowing in said parallel winding.   10 Motor starting device according to claim 8, wherein said electric motor control means comprises a field current reduction means for reducing the field current flowing in a field winding 10 (series winding) of the electric motor , and the electric motor control means reduces the field current of the electric motor using the field current reduction means.   An engine starting device according to claim 8, wherein said electric motor control means reduces the field current of the electric motor in accordance with the number of revolutions of the motor or the starter. The engine starting device according to claim 10, wherein said electric motor control means reduces the field current of the electric motor in accordance with a position of the crankshaft in the motor.   The engine starting device according to claim 12, wherein said electric motor control means reduces the field current of the electric motor after a piston has reached top dead center in any of the cylinders after starting. of the motor.   The motor starting device according to claim 35 8, wherein said electric motor control means establishes an electric current value which maximizes the power of the electric motor as a target control value for the field current.   An engine starting device according to claim 8, wherein said electric motor control means stops the field current reduction control when the oil temperature or an engine coolant temperature is lower that a second predetermined temperature, which is lower than the first predetermined temperature for evaluating whether the catalytic converter is in an inactive state or not.  16 An engine starting device according to claim 8, wherein said electric motor control means stops the field current reduction control when an oil temperature or an engine coolant temperature is higher than a third predetermined temperature, which is higher than the first predetermined temperature for evaluating whether the catalytic converter is in an inactive state or not.   The engine starting device according to claim 8, wherein said electric motor control means stops the field current reduction control when the engine or starter speed has failed to reach a predetermined speed. 18 A motor starting device according to claim 8, wherein said electric motor control means stops the field current reduction control when a battery is in a low charge state.   19 An engine starting device according to claim 35 9, comprising a supply means for passing a field current in the parallel winding, separately from a battery, wherein said electric motor control means stops 40 reducing the field current when the supply means is at a state of charge lower than a predetermined level of charge of the battery.   An engine starting device according to claim 7, wherein said electric motor provided in the starter is a direct current motor.   The engine starting device according to claim 10 2, wherein the engine is started using the first starter when an oil temperature or an engine coolant temperature is lower than a second temperature predetermined temperature which is lower than the first predetermined temperature for evaluating whether the catalytic converter is in an inactive state or not.   22 An engine starting device according to claim 2, in which the engine is started using the first starter when the oil temperature or the engine coolant temperature is higher than a third predetermined temperature, which is higher than the first predetermined temperature for evaluating whether the catalytic converter is in an inactive state or not.   23 The engine starting device according to claim 2, wherein when the engine has been started using the second starter but, if the engine speed or the second starter fails to reach a predetermined speed, the engine is started in tilting from the second starter to the first starter. 24 An engine starting device according to claim 2, wherein the engine is started using the first starter when the state of charge of a battery is low.   An engine starting device according to claim 1, wherein when the engine speed is higher than a predetermined speed, the amount of fuel injection is reduced compared to a case where the catalytic converter is in an active state . 26 An engine starting device according to claim 25, wherein when the engine speed is higher than the predetermined speed, the amount of fuel injection is reduced according to the air / fuel ratio.   27 Engine starting device according to claim 15 1, wherein the injection of fuel is started after it is detected that an intake manifold pressure in the engine is less than a predetermined value.   28 An engine starting device according to claim 1, wherein the injection of fuel is started after it is detected that the engine speed is higher than a predetermined speed. 29. An engine starting device according to claim 1, in which the injection of fuel is started after it is detected that the total number of engine revolutions counted from starting the engine has reached a predetermined value.   An engine starting device according to claim 1, wherein the fuel injection is started after it is detected that a predetermined time has elapsed since an engine started. 31. An engine starting device according to claim 1, in which when starting the engine by driving the engine at high speed, a threshold speed for perfect combustion is modified in accordance with the engine speed.   32. The engine starting device according to claim 31, wherein when the engine speed has reached the threshold speed for perfect combustion, the operation of the starter is stopped.