JP2003328910A - Engine starting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an engine starting device wherein simplification of a device, cut back of waste power consumption and high quietness are realized. <P>SOLUTION: When a physical quantity supposed that starting torque exceeds a given level is detected, the torque-number of revolutions characteristics of a starter 2 are varied to the low torque side by a given level. This constitution improves durability and reliability of the starter 2 and a torque transfer mechanism, reduces size and weight, decreases the generation of noise and vibration during starting, and suppresses consumption of a battery. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine starting device.

[0002]

2. Description of the Related Art In theory, any type of electric motor can be adopted as a conventional engine starting device.
The method of using a series winding field coil with a large starting torque as a starter motor (DC series winding motor or DC compound winding motor) is particularly suitable, and the DC series winding motor with the largest starting torque is used as a starter motor, and the generated torque is The most widely adopted method is to transmit the torque to the crankshaft of the engine through a torque transmission mechanism consisting of a belt and pulley mechanism.

There is also known a system in which an engine starting and a subsequent power generation are simultaneously performed by using a generator motor composed of a synchronous machine (brushless DC motor). Also in this generator-motor, it is preferable that most of the field flux is generated by the field current in order to suppress the generated voltage (electromotive force) at high speed. Therefore, as a starter motor, a field winding type synchronous machine is used. Adoption is considered preferred.

As a conventional control in the above-mentioned starter motor, it is general to start and stop the magnet switch by connecting and disconnecting a magnet switch by an ignition switch or an engine automatic start command.

[0005]

It has been found that such a conventional engine starter has the following problems.

First, it is necessary to set the torque-rotational speed characteristics of the starter motor so that the engine can be driven even under the assumed worst condition.

The load torque seen from the starter motor becomes the largest immediately after the starter motor is energized until the engine gets over the first top dead center, that is, in the low rotation range. At this time, the starter motor is within the allowable range. It is necessary to design so that the generated torque (its worst value) can be generated so as to exceed the load torque by a predetermined level even under the worst condition.

The worst condition within the allowable range is, in particular, the minimum level of the battery voltage within the allowable range and the maximum level of the motor temperature within the allowable range (the motor resistance becomes maximum and the torque decreases). This is the case. However, when the starter motor designed in this way is driven under the best conditions, the generated torque becomes an excessively large value, greatly exceeding the worst value. The best condition is particularly when the battery voltage is at the maximum level within the allowable range and the motor temperature is at the minimum level within the allowable range (motor resistance is minimized and torque increases). Therefore, the torque transmission mechanism is required to endure the excessive value of the generated torque without any problem. Therefore, the torque transmission mechanism has the strength and durability to transmit the excessive generated torque without any problem over time. Need to be designed.

However, the torque-rotational speed characteristic of the starter motor has a substantially hyperbolic shape, and it becomes very steep especially in a DC series-wound motor often used as a starter motor. Torque) fluctuates greatly due to the above-mentioned fluctuations in the battery voltage and the motor temperature, and this fluctuation is particularly noticeable in a DC series motor.

For this reason, conventionally, the strength and durability of a torque transmission mechanism such as a gear or a belt / pulley mechanism for transmitting the torque generated by a starter motor is designed to withstand the above-mentioned excessive value of the generated torque (starting torque). Since it was necessary, the size of the torque transmission mechanism was increased and the manufacturing cost was increased. In addition, the output of an excessively large generated torque, which is not essential by the starter motor, causes a problem that the battery is wasted and the noise and vibration are undesirably increased. In particular, this problem has become more important in an idle stop vehicle that requires frequent starter motor activation.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an engine starting device which is simple and realizes a reduction in useless power consumption, and which is rich in quietness.

[0012]

An engine starter according to the present invention comprises a starter motor for starting an engine, a detection means for detecting a physical quantity that affects a starting torque of the starter motor, and the starter motor based on the physical quantity. And a torque control unit for changing the torque-rotation speed characteristic of the motor, and when the physical quantity that the starting torque is assumed to exceed a predetermined level is detected, the torque-rotation speed characteristic is changed to a low torque side, or The torque-rotational speed characteristic is changed to a high torque side when the physical quantity assumed to cause the starting torque to fall below a predetermined level is detected.

That is, the engine starter of the present invention is
When the operating environment of the engine starter is assumed to increase the starting torque of the starter motor excessively, the torque-rotational speed characteristic of the starter motor is changed to the low torque side. Can be prevented from excessively increasing, and as a result, the torque transmission mechanism for transmitting the torque of the starter motor to the engine can be reduced in size and weight and simplified without lowering its durability. At the same time, it is possible to reduce noise and vibration at the time of starting the engine due to generation of an excessive starting torque, and suppress battery consumption.

Further, the engine starter of the present invention makes the torque-rotational speed characteristic of the starter motor on the high torque side (torque change) when the operating environment of the engine starter is assumed to excessively reduce the starting torque of the starter motor. It means the side that increases the torque (including the change from the low torque characteristic to the normal torque characteristic) to increase the torque.Therefore, depending on the operating environment, the starting torque of the starter motor is excessively reduced when starting the engine, which hinders starting. As a result, it is not necessary to unnecessarily excessively increase the torque of the starter motor except when the starting torque is abnormally reduced. And simplification can be achieved without reducing its durability, and an excessive starting torque is generated. Noise at the time of starting the engine due to, it is possible to realize the reduction and suppression of battery consumption of vibration.

More specifically, as described above, the normal starter motor has a torque-rotational speed characteristic of a substantially hyperbolic shape, and has the largest torque at startup (referred to as startup torque).
When the torque-rotational speed characteristic slightly changes due to fluctuations in operating environment, particularly temperature and battery voltage, this starting torque changes greatly. Naturally, the starter motor is required to generate the required starting torque even in the worst operating environment in which the starting torque is significantly reduced, so various starter motors that affect the torque-rotational speed characteristic that constitutes the operating environment are referred to here. If the parameters (physical quantities) change to the torque increasing side, respectively, the starting torque will greatly increase due to their synergistic effect.

In most cases at the time of starting, the operating environment rarely becomes the above-mentioned worst environment, and as a result, the starter motor has to be started with an almost excessive starting torque at the time of normal starting, and the vehicle is quiet. Performance, useless battery power consumption, and increase in strength of the torque transmission mechanism and the starter motor.

As described above, the problem can be solved by the present invention which prevents the excessive starting torque or the excessive starting torque by adjusting the torque-rotational speed characteristic according to the operating environment.

In a preferred mode, the torque control means changes the torque-rotation speed characteristic so that the starting torque approaches a predetermined starting torque target value based on the physical quantity. Particularly preferably, the torque control means, on the basis of the physical quantity, that is, the detected operating environment, indicates that the torque-rotation speed characteristic is on the low torque side (the side that reduces the torque, when the assumed starting torque is excessive, and indicates the normal torque characteristic). From the state to the low torque characteristic) and when the assumed starting torque is too small, the torque-rotation speed characteristic is high torque side (meaning the side that increases the torque). (Including changes to)).
Thereby, the above effect can be obtained.

In a preferred embodiment, the physical quantity has a correlation with at least one of motor temperature, engine temperature, battery temperature, battery voltage and battery output,
The above effects can be achieved well.

To explain further, an increase in motor temperature shifts the torque-rotational speed characteristic to a low torque side due to an increase in winding electrical resistance. Since a large current flows at the time of starting, an increase in the electric resistance of the winding causes a remarkable decrease in the armature current and field current of the motor and a non-negligible decrease in the starting torque. Since the engine temperature generally has a positive correlation with the motor temperature, the same effect as the above is obtained. When the battery voltage drops due to a decrease in battery capacity or deterioration over time, the increase in internal resistance of the battery causes a significant decrease in the armature current and field current of the starter motor, and a non-negligible decrease in starting torque. These problems can be solved by this aspect.

In a preferred mode, the torque-rotational speed characteristic is changed to a low torque side when the motor temperature is estimated to be a predetermined level or lower, and the torque-rotation is changed when the motor temperature is estimated to be a predetermined level or higher. The numerical characteristics are changed to the high torque side (including the normal side as described above).

In a preferred mode, the torque control means changes the torque-rotation speed characteristic to a low torque side when the battery output is estimated to be above a predetermined level, and the battery output is estimated to be below a predetermined level. In this case, the torque-rotational speed characteristic is changed to the high torque side (including the normal side as described above).

In a preferred mode, when the engine load torque is estimated to be equal to or higher than a predetermined level, the torque-rotational speed characteristic is changed to a high torque side (including the normal side as described above), The torque-rotational speed characteristic is changed to a low torque side when it is estimated to be below a predetermined level.

In the above aspect in which the torque-rotational speed characteristic is changed based on the engine temperature, the torque control means is such that the engine temperature is equal to or lower than a second predetermined level lower than the predetermined level or higher than the predetermined level. When it is estimated that the third predetermined level or higher, the torque-rotational speed characteristic is changed to a high torque side. This makes it possible to shift the torque-rotational speed characteristic of the starter motor to a high torque side when the engine has a large friction resistance and a large starting torque is required for starting the engine in cold weather. It is possible to surely start the engine, and it is possible to prevent the starting torque from becoming excessive at other times. The engine temperature can also be estimated from the motor temperature.

In a preferred mode, the torque control means changes the torque-rotational speed characteristic before starting the starter motor based on the physical quantity detected before starting the engine. This makes it possible to change the starting torque immediately after the starter motor is started.Because this change is completed before the starter motor is started, the circuit components for changing the torque-rotational speed characteristics are switched before power is supplied. Since the operation is performed, it is possible to prevent the consumption of the abnormal voltage or the like.

In a preferred mode, the torque control means ends or reduces the shift of the torque-rotational speed characteristic to the low torque side before the cranking of the engine ends. As a result, it is possible to reliably prevent the above-mentioned excessive increase in the starting torque, and increase the torque generated by the starter motor during the subsequent cranking period (even if the starting torque is increased smaller than the starting torque, there is no problem in specification). As a result, a quick engine start can be realized.

When the torque-rotational speed characteristic is shifted to the low torque side, the torque control means determines the end timing based on the detected state of the engine starting system. As a result, it is possible to perform optimum control according to the above-mentioned state of the engine starting system (for example, motor temperature, engine temperature, battery voltage, motor current).

In a preferred mode, the torque control means changes the torque-rotational speed characteristic based on the physical quantity detected during starting of the engine, so that not only the starting torque but also the engine rotational speed during cranking. The acceleration characteristics of can also be controlled to an ideal state. As this physical quantity, for example, the armature current and / or field current of the starter motor, which can be easily detected, can be adopted.

In a preferred mode, the starter motor comprises a DC electric motor having a series winding. As described above, the DC direct-winding motor has a steep torque-rotational speed characteristic, and since the change in the starting torque due to the change in the operating environment is large, the above effect is large.

In a preferred mode, the starter motor is switched between two stages of high torque side or normal torque side and low torque side.

Aspects other than those described above will be described in the following embodiments.

[0032]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of an engine starting device of the present invention will be described with reference to the following examples.

[0033]

(Embodiment 1) (Circuit configuration) FIG. 1 shows an engine starting system, 1 is an engine, 2 is a starter, 3 is a belt, 4 is a crankshaft pulley, 5 is a starter pulley, 6 is an idle stop ECU, and 7 is an engine. The ECU and 8 are batteries.

The starter 2 includes a starter motor composed of a DC series-wound electric motor, and a starter control circuit for controlling the starter motor. This control circuit is an idle stop E.
The starter motor is controlled based on the starter control signal output by the CU 6.

The belt 3 connects the crankshaft pulley 4 and the starter pulley 5 together to form a torque transmission mechanism.

The idle stop ECU 6 is an engine EC
The above-mentioned starter control signal is formed based on a signal input from U7 or a brake ECU (not shown), and
Idle stop operation of engine 1, that is, engine 1
It controls the automatic stop and restart of. The idle stop control itself performed by the idle stop ECU 6 is not the subject matter of the present invention, and thus a detailed description thereof will be omitted.

The starter 2 is shown in FIG.

In this embodiment, the starter 2 is composed of a starter motor 21, preferably a DC series winding motor, a magnet switch 22, and a starting current cut relay 23, and the magnet switch 22 and the starting current cut relay 23 are described above. The starter control circuit. The starting current cut relay 23 has a configuration in which a normally open contact 231 and a resistor 232 are connected in parallel.

To explain this operation, the idle stop ECU 6 preferably starts the startup current cut relay 23 before closing the magnet switch 22 at startup on the high torque side.
, The starter current immediately after starting the starter motor 21 by closing the magnet switch 22 is supplied to the starter motor 21 without being cut, and the starter motor 21 realizes a torque-rotational speed characteristic having a large starting torque. . On the contrary, the idle stop ECU 6 preferably uses the magnet switch 22 at the time of starting on the low torque side.
Before opening the starter current cut relay 23, the magnet switch 22 is closed and the starter motor 2 is closed.
The starting current immediately after starting 1 is the starting current cut relay 2
Limited by the voltage drop across resistor 232 of No. 3, the starter motor 21 achieves a torque-speed characteristic with a small starting torque. In the above aspect, the starter motor 21
Is not limited to the DC series-wound motor, and the limitation of the armature current is not limited to the above-mentioned starting current cut relay 23, and a known method can be adopted.

The effect of using the above-mentioned armature current limiting method will be described with reference to FIG.

SH indicated by a chain double-dashed line indicates a torque-rotational speed characteristic when the armature current is not limited in a state where the operating environment fluctuates to the high torque side. The starting torque of the torque-rotational speed characteristic SH becomes TH, which is significantly higher than the required starting torque Tm required for starting the engine, and therefore is not actually used.

SH 'indicated by the solid line shows the torque-rotational speed characteristic when the armature current is limited in the state where the operating environment fluctuates to the high torque side. The starting torque of the torque-rotational speed characteristic SH 'becomes TH', and the excess torque that exceeds the required starting torque Tm necessary for starting the engine can be significantly reduced.

Further, in the mode shown in FIG. 3, when the engine 1 starts cranking and the required torque and the torque of the torque-rotational speed characteristic SH have decreased to the starting torque TH '(and / or the torque-rotational speed). (At the stage when the torque on the number characteristic TH 'has decreased to the substantially required starting torque Tm), the limitation of the armature current is terminated and the torque-revolution speed characteristic SH' returns to the torque-revolution speed characteristic SH.
That is, the armature current limiting state is returned to the armature current non-limiting state.

As a result, the acceleration force during cranking can be improved and the engine starting time can be shortened while maintaining the torque generated by the starter motor 21 at a level not exceeding TH '. As a result, the engine can be restarted particularly quickly after the idling stop, and the driver who starts the vehicle can be prevented from feeling uncomfortable.

SL indicated by the solid line shows the torque-rotational speed characteristic when the armature current is not limited when the operating environment fluctuates toward the low torque side. The starting torque of the torque-rotational speed characteristic SL is TL, which is set higher than the required starting torque Tm necessary for starting the engine.

SL 'indicated by a two-dot chain line shows a torque-rotational speed characteristic when the armature current is limited in a state where the operating environment fluctuates to the low torque side. Since the starting torque TL 'of the torque-rotational speed characteristic SL' is lower than the necessary starting torque Tm required for starting the engine, it is not actually used.

That is, in FIG. 3, by limiting the armature current from immediately after the start of the engine 1 to a certain period during cranking in a state where the operating environment fluctuates to the high torque side, an originally excessive torque is generated. It can be reduced within a range that does not hinder the engine starting, and thus the above-described various operational effects can be achieved.

The state in which the operating environment fluctuates to the high torque side means a state in which the motor temperature is low and the battery output is high, and the state in which the operating environment fluctuates to the low torque side. Means that the motor temperature is high and the battery output is low. Detection of battery output may be by battery voltage, for example. Of course, either the motor temperature or the battery output may be monitored to determine whether to limit the armature current.

[0049]

Second Embodiment Another mode of the starter 2 shown in FIG. 1 is shown in FIG. However, circuit elements having the same main function as the circuit elements of FIG. 2 may be denoted by the same reference numerals.

In this embodiment, the starter 2 comprises a starter motor 21, a magnet switch 22, and a field coil switching relay 24.
2 and the field coil switching relay 24 constitute the starter control circuit described above. The starter motor 21 including a DC series-wound electric motor includes a first field coil 214, a second field two coil 215, and an armature coil (armature) 213, and the first field coil 214 and the second field two coil. Coil 2
15 has the same number of turns, but this number of turns does not have to match.

In this embodiment, the field coil switching relay 24
Is driven to switch between the series connection and the parallel connection of the field coils 214 and 215. The field coil switching relay 24 includes a normally closed contact relay 241 and a switching relay 242.

When the idle stop ECU 6 does not energize the coil of the field coil switching relay 24, the two movable contacts of the field coil switching relay 24 are in the positions shown in FIG. 3, and the field coils 214 and 215 are connected in parallel. It is in a state. As a result, the armature current is transmitted to the field coil 21.
The field current is substantially halved and the torque-rotational speed characteristic shifts to the low torque side. Conversely, when the idle stop ECU 6 energizes the coil of the field coil switching relay 24, the field coil switching relay 24
The four movable contacts are shifted to the positions opposite to those in FIG. 4, and the field coils 214 and 215 are connected in series. This allows
The armature current flows through both field coils 214 in series, the field current is approximately doubled, and the torque-rotation speed characteristic shifts to the high torque side.

The effect of using the above field coil switching system will be described with reference to FIG.

SH indicated by a chain double-dashed line represents a torque-rotational speed characteristic when the field coils are connected in series in a state where the operating environment fluctuates toward the high torque side. The starting torque of the torque-rotational speed characteristic SH becomes TH, which is significantly higher than the required starting torque Tm required for starting the engine, and therefore is not actually used.

SH 'shown by the solid line shows the torque-rotational speed characteristic when the field coils are connected in series in a state where the operating environment fluctuates toward the high torque side. The starting torque of the torque-rotational speed characteristic SH 'becomes TH', and the excess torque that exceeds the required starting torque Tm necessary for starting the engine can be significantly reduced.

As a result, the excessive starting torque can be reduced while maintaining the torque generated by the starter motor 21 at a level necessary and sufficient for starting the engine.

SL indicated by the solid line represents the torque-rotational speed characteristic when the field coils are connected in series in a state where the operating environment fluctuates toward the low torque side. The starting torque of the torque-rotational speed characteristic SL is TL, which is set higher than the required starting torque Tm necessary for starting the engine.

If the field coils are connected in parallel while the operating environment fluctuates toward the low torque side, the starting torque will be lower than the required starting torque Tm required for starting the engine, so the torque is not actually used. The rotation speed characteristic is not shown.

That is, in FIG. 5, by limiting the armature current immediately after the engine 1 is started in a state where the operating environment fluctuates to the high torque side, an originally excessive torque does not hinder the engine starting. It can be reduced within the range, whereby the above-described various operational effects can be achieved. Of course, also in this case, the return from the parallel connection of the field coils to the series connection can be performed in the middle of the cranking, but it is not realistic because the inductance of the field coils is large.

The state in which the operating environment fluctuates toward the high torque side means a state in which the motor temperature is low and the battery output is high, and the state in which the operating environment fluctuates toward the low torque side. Means that the motor temperature is high and the battery output is low. Detection of battery output may be by battery voltage, for example. Of course, in this case, either the motor temperature or the battery output may be monitored to determine whether to switch the field coil.

[0061]

Third Embodiment Another embodiment of the starter 2 is shown in FIG.

FIG. 6 shows an engine starting device, 21 is a starter motor consisting of a direct current winding motor, 22 is a magnet switch, 25 is a relay, 26 is an ignition switch, 6 is an idle stop ECU, 8 is a battery, and 9 is a battery.
Is a short circuit relay. The starter motor 21 is a field coil 21 that constitutes a series winding field winding with the intermediate tap 10.
4, 215 and an armature coil (armature) 213 are connected in series. When the pair of contacts of the short-circuit relay 9 is turned on, the field coil 214 is short-circuited.

The operation will be described. When the ignition switch 26 is turned on and the relay 25 is closed, the magnet switch 22 is closed and the starter motor 21 is energized from the battery 8, and the starter motor 21 is normally activated by the high torque-rotational speed characteristic. It Further, the idle stop ECU 6 determines whether or not the engine can be automatically stopped and the automatic restart after that based on an input signal from a sensor or the like.
By energizing the magnet switch 22, the starter motor 21 is activated by the low torque-revolution speed characteristic.

Further, if the idle stop ECU 6 determines that the operating environment shifts the torque-rotational speed characteristic of the starter motor 21 to the high torque side by the external input,
After closing the short circuit relay 9, the magnet switch 22 is closed. As a result, the field coil 214 is short-circuited, the field magnetic flux of the starter motor 21 is significantly reduced, the torque-rotational speed characteristic shifts to the low torque side, and it is possible to avoid engine start due to excessive torque.

A modification of the circuit of FIG. 6 is shown in FIG.

In this modification, the short circuit relay 9 of FIG. 1 is replaced with a short circuit transistor 90 and a flywheel diode D. Other circuit configurations are the same as those in FIG. If the engine automatic restart is determined, the idle stop ECU 6 closes the magnet switch 22 and starts the DC series-wound motor 21.

The above effect is achieved by closing the short-circuit transistor 90 when it is determined that the operating environment shifts the torque-rotational speed characteristic to the high torque side and opening the short-circuit transistor 90 when it is determined otherwise. Can play.

(Control Mode) Next, the idle stop EC
An example of control operation at the time of automatic engine restart performed by U6 will be described below with reference to the flowchart shown in FIG.

First, it is determined whether the engine is automatically stopped by the eco-run (100), and if the engine is automatically stopped, it is determined whether the engine automatic restart condition is satisfied (102). The data is read from the engine ECU 7 or the sensor (104).

Next, it is judged whether the torque of the starter motor 21 is excessive or not based on the judgment result of the operating environment (106). When it is judged that the torque is excessive, the torque-rotational speed characteristic of the starter motor 21 is determined. Shift to the low torque side (108). The shift of the torque-rotational speed characteristic may be performed by using the method of each of the above-described embodiments. In addition,
The torque-rotation speed characteristic of the starter motor 21 is initially set to the high torque side.

In this embodiment, the motor temperature, the engine temperature, and the battery voltage are used as the operating environment data, the engine temperature is, for example, 0 to 100 ° C., the motor temperature is, for example, 50 ° C. or less, and the battery voltage is Is greater than or equal to a predetermined threshold value, it is determined that the torque is excessive. That is, it is considered that the lubricating oil viscosity of the engine 1 is high when the engine temperature detected by the radiator cooling water temperature is lower than 0 ° C. and the required torque at the time of engine start is large, and when the motor temperature is 100 ° C. or less, the electric power of the motor winding is reduced. It is considered that the torque generated by the motor is increasing due to the decrease in resistance, and when the engine temperature is 100 ° C or higher, the lubricating oil viscosity is low and the lubricating oil leaks downward from the piston surface. It is assumed that the required torque of is increased. That is, in this embodiment, it is determined that the torque is excessive when the engine temperature is 0 to 100 ° C., the motor temperature is 50 ° C. or lower, and the battery voltage is equal to or higher than a predetermined threshold value.

In addition, in the above, the logical product of each condition is used as the determination condition, but the logical sum of the above conditions may be used as the determination condition.

In addition, the battery temperature may be detected, and when the battery temperature is within a predetermined range, for example, 20 to 50 ° C., the torque excess side may be set. It is well known that battery output drops at low and high temperatures.

In addition, since the battery temperature and the motor temperature have a correlation, the motor temperature may be estimated from the battery temperature and vice versa. Further, it may be determined whether the torque is on the excessive side (high torque side) based on a part or all of the states of the motor temperature, the engine temperature, the battery voltage, and the battery temperature.

Next, the magnet switch 22 is turned on (110) for a predetermined time (at least during cranking).
The process waits until the time passes (112), and when the time passes, the torque-rotational speed characteristic of the starter motor 21 is returned to the high torque side (114). If the torque-rotational speed characteristic is not shifted to the low torque side, step 114 may be ignored. Further, instead of waiting for a predetermined time in step 112, the torque-rotation speed characteristic may be returned to the high torque side when the engine speed exceeds the predetermined rotation speed.

Next, the engine waits until the engine speed exceeds a predetermined value (116), and when it exceeds, the starter 2 is returned to the initial state on the assumption that the engine start is completed (11).
8).

By doing so, the above-mentioned effects can be obtained. (Modification) The torque-rotational speed characteristic of the starter motor 21 may be changed by another known method. Also,
The operation of canceling the armature current limitation during cranking or switching the field coils in series is performed after a predetermined time set from the start of energization, when the current is below a predetermined value or when the rotation speed is a predetermined value. You may go when it exceeds. Further, in the above-described embodiment, the automatic engine restart after the idle stop is described, but it may be performed at the manual start by turning on the ignition switch. Alternatively, two starters 2 may be provided to drive both when high starting torque is required.

Further, the torque-rotational speed characteristic may be freely changed according to the operating environment by PWM controlling the armature current of the starter motor or the like. In this case, it is preferable to adjust the torque-rotational speed characteristic so as to approach an appropriate starting torque target value in view of the driving environment.

Further, the operating environment data, for example, the state of the engine starting system (for example, the motor temperature, the engine temperature, the battery voltage, the motor current) is used to determine the point of time at which the torque-rotation speed characteristic returns to the high torque side during cranking. May be used. Alternatively, the magnitude of the current supplied to the starter motor 21 and its waveform may be directly monitored to adjust the magnitude to an appropriate level. Further, the return time point may be determined based on the rate of increase in engine speed. The motor temperature can also be indirectly estimated based on data such as the engine water temperature and the time elapsed since the previous start. After this return operation, when it is determined that the current is excessive (the torque is excessive), the torque-rotational speed characteristic may be shifted to the low torque side again. After the torque-rotational speed characteristic is shifted to the low torque side and started, the torque-rotational speed characteristic may be returned to the original state if the increase rate of the engine rotational speed is small. As a matter of course, the information from various sensors mounted on the vehicle can be used as the driving environment data. It goes without saying that the starter 2 can be connected to the engine 1 through a torque transmission mechanism other than the belt / pulley mechanism.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an engine starting circuit system according to a first embodiment.

FIG. 2 is a circuit diagram showing the starter shown in FIG.

FIG. 3 is a torque-rotational speed characteristic diagram showing the characteristics of the starter shown in FIG.

FIG. 4 is a circuit diagram showing a starter according to a second embodiment.

5 is a torque-rotational speed characteristic diagram showing the characteristics of the starter shown in FIG.

FIG. 6 is a circuit diagram showing a starter according to a third embodiment.

FIG. 7 is a circuit diagram showing a modification of the starter of the third embodiment.

FIG. 8 is a flowchart showing an engine automatic restart control operation.

[Explanation of symbols]

1 engine 2 starters 3 belts 6 Idle stop ECU (control means)

Continued front page    (72) Inventor Masahiko Nagata             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO

Claims (14)

[Claims] 1. A starter motor for starting an engine, a detection means for detecting a physical quantity that affects a starting torque of the starter motor, and a control means for changing a torque-rotational speed characteristic of the starter motor based on the physical quantity. The control means changes the torque-rotational speed characteristic to a low torque side when the physical quantity that the starting torque is assumed to exceed a predetermined level is detected, or the starting torque is a predetermined level. An engine starting device, wherein the torque-rotational speed characteristic is changed to a high torque side when the physical quantity that is assumed to be below is detected. 2. The engine starting device according to claim 1, wherein the torque control means changes the torque-rotational speed characteristic so that the starting torque approaches a predetermined starting torque target value based on the physical quantity. Engine starter. 3. The engine starting device according to claim 1, wherein the physical quantity has a correlation with at least one of a motor temperature, an engine temperature, a battery temperature, a battery voltage, and a battery output. 4. The engine starter according to claim 3, wherein the torque control means changes the torque-rotational speed characteristic to a low torque side when the motor temperature is estimated to be equal to or lower than a predetermined level. Is estimated to be equal to or higher than a predetermined level, the engine starter for changing the torque-rotational speed characteristic to a high torque side. 5. The engine starter according to claim 3, wherein the torque control means changes the torque-rotational speed characteristic to a low torque side when the battery output is estimated to be a predetermined level or higher, and the battery output. The engine starting device for changing the torque-rotational speed characteristic to the high torque side when the engine is estimated to be below a predetermined level. 6. The engine starting device according to claim 3, wherein the torque control means changes the torque-rotation speed characteristic to a high torque side when the load torque of the engine is estimated to be equal to or higher than a predetermined level. An engine starting device for changing the torque-rotational speed characteristic to a low torque side when the load torque of the engine is estimated to be below a predetermined level. 7. The engine starter according to claim 6, wherein the torque control means is a third predetermined value at which the engine temperature is lower than the second predetermined level lower than the predetermined level or higher than the predetermined level. An engine starting device that changes the torque-rotational speed characteristic to a high torque side when it is estimated to be at or above a level. 8. The engine starting device according to claim 1, wherein the torque control means changes the torque-rotational speed characteristic before starting the starter motor based on the physical quantity detected before starting the engine. Engine starter. 9. The engine starting device according to claim 8, wherein the torque control means ends or reduces the shift of the torque-rotational speed characteristic to the low torque side before the end of cranking of the engine. 10. The engine starter according to claim 9, wherein the torque control means determines the end timing based on the detected state of the engine start system. 11. The engine starting device according to claim 1, wherein the torque control means changes the torque-rotational speed characteristic based on the physical quantity detected during starting of the engine. 12. The engine starter according to claim 11, wherein the physical quantity is an armature current of the starter motor and / or
Or an engine starting device consisting of a field current. 13. The engine starting device according to claim 1, wherein the starter motor is a DC motor having a series winding. 14. The engine starting device according to claim 1, wherein the starter motor is switched between a high torque side or a normal side and a low torque side.