JP4048826B2 - Engine starter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an engine starting device.
[0002]
[Prior art]
Theoretically, any type of electric motor can be used as a conventional engine starter, but there are methods (DC series motor or DC compound motor) that use a series coil having a large starting torque as a starter motor. In particular, a direct current motor having the largest starting torque is used as a starter motor, and the generated torque is transmitted to the engine crankshaft through a torque transmission mechanism including a belt / pulley mechanism.
[0003]
There is also known a system in which engine starting and subsequent power generation are performed simultaneously using a generator motor composed of a synchronous machine (brushless DC motor). In this generator motor as well, it is preferable to generate most of the field flux by the field current in order to suppress the generated voltage (electromotive voltage) at high speed. For this reason, the field winding type synchronous machine is used as a starter motor. Employment is considered suitable.
[0004]
As a conventional control in the above-described starter motor, it is general to start and stop the magnet switch by intermittently switching it with an ignition switch or an engine automatic start command.
[0005]
[Problems to be solved by the invention]
It has been found that such a conventional engine starting device has the following problems.
[0006]
First, it is necessary to set the torque-rotation speed characteristic of the starter motor so that the engine can be driven even under the worst case conditions.
[0007]
The load torque seen from the starter motor is the largest immediately after starting from when the starter motor is energized until the engine goes over the first top dead center, that is, in the low speed range. At this time, the starter motor is in the worst condition within the allowable range. However, it is necessary to be designed so that the generated torque (its worst value) can be generated so as to exceed the load torque by a predetermined level.
[0008]
The worst condition within the allowable range is particularly when the battery voltage is at the minimum level within the allowable range and the motor temperature is at the maximum level within the allowable range (the motor resistance is maximized and the torque is reduced). . However, when the starter motor designed in this way is driven under the best conditions, the generated torque greatly exceeds the worst value and becomes an excessive value. This 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 (the motor resistance is minimized and the torque is increased). Therefore, the torque transmission mechanism must be able to withstand the excessive value of the generated torque without any problem. For this reason, the torque transmission mechanism has strength and durability that can transmit the excessive generated torque without any problem over time. Need to be designed as such.
[0009]
However, the torque-rotation speed characteristic of the starter motor has a substantially hyperbolic shape, and is particularly steep in a DC series motor that is frequently used as a starter motor. Therefore, the start torque (torque at 0 rpm) is included in the torque-rotation speed characteristics. ) Greatly vary due to the above-described variations in battery voltage and motor temperature, and this variation is particularly significant in a DC series motor.
[0010]
For this reason, conventionally, it has been necessary to design the strength and durability of a torque transmission mechanism such as a gear or belt / pulley mechanism for transmitting the generated torque of the starter motor to withstand the above excessive value of the generated torque (starting torque). As a result, the torque transmission mechanism is increased in size and the manufacturing cost is increased. In addition, outputting an excessively generated torque that is not essential for the starter motor also causes problems such as unnecessary battery consumption and an undesirable increase in noise vibration. In particular, this problem has become more important in idle stop vehicles that require frequent starter motor activation.
[0011]
The present invention has been made in view of the above problems, and an object of the present invention is to provide an engine starter that realizes simplification of the device and reduction of wasteful power consumption and is rich in silence.
[0012]
[Means for Solving the Problems]
1st and 2nd below The engine starter according to the present invention includes a starter motor for starting the engine, a detection unit that detects a physical quantity that affects a starting torque of the starter motor, and a torque that changes a torque-rotation speed characteristic of the starter motor based on the physical quantity. Control means, and when the physical quantity that is assumed that the starting torque exceeds a predetermined level is detected, the torque-rotational speed characteristic is changed to a low torque side, or when the starting torque falls below a predetermined level When the assumed physical quantity is detected, the torque-rotational speed characteristic is changed to a high torque side.
[0013]
That is, the engine starter of the present invention changes the torque-rotation speed characteristic of the starter motor to the low torque side when the operating environment of the engine starter is assumed to excessively increase the starting torque of the starter motor. It is possible to prevent the starter motor starting torque from excessively increasing at the start of the engine depending on the environment. As a result, the torque transmission mechanism that transmits the torque of the starter motor to the engine is reduced in size and weight, and its durability is improved. In addition, it is possible to realize reduction of noise and vibration during engine start-up and suppression of battery consumption by generating an excessive starting torque.
[0014]
Further, the engine starter of the present invention has a torque-rotational speed characteristic of the starter motor on the high torque side (torque increase side) when the operating environment of the engine starter is assumed to excessively reduce the starter motor start torque. And the torque is increased by changing from low torque characteristics to normal torque characteristics), and the start torque of the starter motor will decrease excessively when starting the engine due to the operating environment, causing problems in starting. As a result, there is no need to unnecessarily increase the torque of the starter motor except when the start-up torque is abnormally reduced. Can be realized without reducing its durability, and generating excessive starting torque Noise at the time of starting the engine that, it is possible to realize a reduction as well as the suppression of battery consumption of vibration.
[0015]
More specifically, as described above, a normal starter motor has a substantially hyperbolic torque-rotational speed characteristic, and generates the largest torque (referred to as starting torque) at the time of starting, which is caused by fluctuations in the operating environment, particularly temperature and battery voltage. When the torque-rotational speed characteristic changes slightly, the starting torque changes greatly. Naturally, the starter motor is required to generate the necessary starting torque even in the worst operating environment in which the starting torque is greatly reduced. Therefore, the starter motor has various effects that affect the torque-rotational speed characteristics constituting the operating environment. When the parameters (physical quantities) fluctuate toward the torque increasing side, the starting torque is greatly increased due to their synergistic effect.
[0016]
For most of the start-up, the driving environment rarely becomes the above-mentioned worst environment, and as a result, the starter motor must be started with almost excessive start-up torque during normal start-up, resulting in poor vehicle quietness. This leads to wasteful battery power consumption and increased torque transmission mechanism and starter motor strength.
[0017]
In this way, the problem can be solved by the present invention in which the torque-rotational speed characteristic is adjusted according to the driving environment to prevent the starting torque from being excessive or the starting torque being excessively low.
[0018]
In a preferred aspect, 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 means that when the assumed starting torque is excessive based on the physical quantity, that is, the detected operating environment, the torque-rotational speed characteristic is reduced to the low torque side (meaning the side to reduce the torque, and the normal torque characteristic). If the assumed start-up torque is too small, the torque-rotational speed characteristic is set to the high torque side (which means the torque is increased, and the low torque characteristic state is changed to the normal torque characteristic). (Including changes to). Thereby, the above-mentioned effect can be acquired.
[0019]
In the first invention, Since the physical quantity has a correlation with at least one of the motor temperature, the engine temperature, the battery temperature, the battery voltage, and the battery output, the above effect can be realized satisfactorily.
[0020]
More specifically, when the motor temperature increases, the torque-rotational speed characteristic is shifted to the low torque side by increasing the winding electrical resistance. Since a large current flows at the time of start-up, an increase in the winding electric resistance causes a significant decrease in the armature current and field current of the motor and a non-negligible decrease in the start-up torque. Since the engine temperature generally has a positive correlation with the motor temperature, the same effects as described above can be obtained. When the battery voltage decreases due to a decrease in the capacity of the battery or its deterioration over time, the increase in the internal resistance causes a significant decrease in the armature current and field current of the starter motor and a resulting decrease in the starting torque that cannot be ignored. These problems can be solved by this aspect.
[0021]
Furthermore, in the first invention, The torque control means changes the torque-rotation speed characteristic to a low torque side when the battery output is estimated to be equal to or higher than a predetermined level, and the torque-rotation speed characteristic when the battery output is estimated to be lower than a predetermined level. Is changed to the high torque side (including the normal side as described above).
[0022]
In a preferred aspect, the torque control means changes the torque-rotation speed characteristic to a low torque side when the battery output is estimated to be equal to or higher than a predetermined level, and when the battery output is estimated to be lower than the predetermined level. The torque-rotational speed characteristic is changed to the high torque side (including the normal side as described above).
[0026]
In the second invention, The torque control means ends 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-described excessive start torque. In Starter motor generation torque during the subsequent cranking period The As a result, the engine can be started quickly.
[0027]
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 start system. Thereby, optimal control according to the state (for example, motor temperature, engine temperature, battery voltage, motor current) of the above-mentioned engine starting system can be performed.
[0028]
Furthermore, in the second invention, Since the torque control means changes the torque-rotation speed characteristic based on the physical quantity detected during the start of the engine, not only the starting torque but also the acceleration characteristic of the engine speed during cranking is in an ideal state. Can be controlled. As the physical quantity, for example, an armature current and / or a field current of the starter motor that is easy to detect can be used.
[0029]
In a preferred aspect, the starter motor is a DC motor having a series winding. The direct current motor has a steep torque-rotational speed characteristic as described above, and the effect is great because the change in the starting torque due to fluctuations in the operating environment is large.
[0030]
In a preferred aspect, the starter motor is subjected to two-stage switching between a high torque side or a normal torque side and a low torque side.
[0031]
Aspects other than those described above will be described in the following embodiments.
[0032]
BEST MODE FOR CARRYING OUT THE INVENTION
Preferred embodiments of the 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, where 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, 7 is an engine ECU, and 8 is a battery.
[0034]
The starter 2 includes a starter motor composed of a DC series motor and a starter control circuit that controls the starter motor. The control circuit controls the starter motor based on a starter control signal output from the idle stop ECU 6.
[0035]
The belt 3 connects the crankshaft pulley 4 and the starter pulley 5 and constitutes a torque transmission mechanism together with them.
[0036]
The idle stop ECU 6 forms the above-described starter control signal based on signals input from the engine ECU 7 and a brake ECU (not shown), and controls the idle stop operation of the engine 1, that is, the automatic stop and automatic restart of the engine 1. . Since the idling stop control itself performed by the idling stop ECU 6 is not the gist of the present invention, the detailed description thereof is omitted.
[0037]
The starter 2 is shown in FIG.
[0038]
In this aspect, the starter 2 is preferably composed of a starter motor 21 composed of a DC series motor, a magnet switch 22, and a starting current cut relay 23. The magnet switch 22 and the starting current cut relay 23 are the starter control described above. The circuit is configured. The starting current cut relay 23 has a configuration in which a normally open contact 231 and a resistor 232 are connected in parallel.
[0039]
Explaining this operation, the idling stop ECU 6 preferably closes the starting current cut relay 23 before closing the magnet switch 22 when starting on the high torque side, thereby closing the magnet switch 22 and starting the starter motor 21. The starting current immediately after the starter motor 21 is energized 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 opens the starting current cut relay 23 preferably before closing the magnet switch 22 when starting on the low torque side, thereby starting immediately after the magnet switch 22 is closed and the starter motor 21 is started. The current is limited by the voltage drop of the resistor 232 of the starting current cut relay 23, and the starter motor 21 realizes a torque-rotational speed characteristic having a small starting torque. In the above aspect, the starter motor 21 is not limited to a direct current DC motor, and the limitation of the armature current is not limited to the starting current cut relay 23 described above, and a known method can be adopted. .
[0040]
The effect of using the above-described armature current limiting method will be described with reference to FIG.
[0041]
SH indicated by a two-dot chain line indicates a torque-rotational speed characteristic in a case where the armature current is not limited in a state where the operating environment is changed to the high torque side. The starting torque of the torque-rotation speed characteristic SH is TH, which is much higher than the required starting torque Tm required for starting the engine, and is not actually used.
[0042]
SH ′ indicated by a solid line indicates a torque-rotational speed characteristic when the armature current is 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 ′, and it is possible to greatly reduce excess torque that exceeds the necessary starting torque Tm required for engine starting.
[0043]
Further, in the embodiment shown in FIG. 3, when the engine 1 starts cranking and the required torque and the torque-torque speed characteristic SH decrease to the starting torque TH ′ (and / or the torque-rotational speed characteristic TH). When the upper torque is reduced to substantially the required starting torque Tm, the armature current limitation is terminated, and the torque-rotational speed characteristic SH ′ is returned to the torque-rotational speed characteristic SH. That is, the armature current limit state returns to the armature current non-limit state.
[0044]
Thereby, while maintaining the generated torque of the starter motor 21 at a level not exceeding TH ′, the acceleration force during cranking can be improved and the engine start time can be shortened. Thereby, especially the engine restart after an idle stop can be made quick, and it can suppress giving a discomfort to the driver who starts a vehicle.
[0045]
SL indicated by a solid line indicates a torque-rotational speed characteristic when the armature current is not limited in a state where the operating environment fluctuates to the low torque side. The starting torque of the torque-rotation speed characteristic SL is TL, which is set higher than the necessary starting torque Tm necessary for starting the engine.
[0046]
SL ′ indicated by a two-dot chain line indicates a torque-rotational speed characteristic in a case where 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-rotation speed characteristic SL ′ is lower than the required starting torque Tm required for starting the engine, it is not actually used.
[0047]
That is, in FIG. 3, by limiting the armature current from immediately after the engine 1 is started to a certain period during cranking in a state where the operating environment fluctuates to the high torque side, the originally excessive torque is set to start the engine. It reduces within the range which does not produce a trouble, and can show | play the various effect mentioned above by this.
[0048]
The state where the operating environment fluctuates to the high torque side here refers to a state where the motor temperature is low and the battery output is high, and the state where the operating environment fluctuates to the low torque side means that the motor The temperature is high and the battery output is low. The detection of the battery output can be based on the battery voltage, for example. Of course, only the motor temperature or the battery output may be monitored to determine whether to limit the armature current.
[0049]
[Example 2]
Another embodiment of the starter 2 shown in FIG. 1 is shown in FIG. However, the same reference numerals may be given to circuit elements having the same main functions as the circuit elements of FIG.
[0050]
In this aspect, the starter 2 is constituted by a starter motor 21, a magnet switch 22, and a field coil switching relay 24, and the magnet switch 22 and the field coil switching relay 24 constitute the above-described starter control circuit. A starter motor 21 composed of a direct current motor is a first field coil 21. 1 And the second field two coil 21 2 And an armature coil (armature) 213, and the first field coil 21 1 And the second field two coil 21 2 Have equal number of turns, but this number of turns is not required to match.
[0051]
In this embodiment, the field coil switching relay 24 is driven to drive the field coil 21. 1 , 21 2 Switch between serial connection and parallel connection. The field coil switching relay 24 includes a normally closed contact relay 241 and a switching relay 242.
[0052]
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 4 In the position shown in FIG. 1 , 21 2 Are connected in parallel. As a result, the armature current is converted into the both-field coil 21. 1 , 21 2 And the field current is substantially Nearly doubled And
Torque speed characteristics High Shift to the torque side. Conversely, when the idle stop ECU 6 energizes the coil of the field coil switching relay 24, the two movable contacts of the field coil switching relay 24 shift to positions opposite to those in FIG. 1 , 21 2 Are connected in series. As a result, the armature current is converted into the both-field coil 21. 1,212 In series, field current is almost Halved The torque-rotation speed characteristic is Low Shift to the torque side.
[0053]
The effect when the above-described field coil switching method is used will be described with reference to FIG.
[0054]
SH indicated by a two-dot chain line indicates that the field coil is operated with the operating environment fluctuating to the high torque side. common The torque-rotational speed characteristics when connected in a row are shown. The starting torque of the torque-rotation speed characteristic SH is TH, which is much higher than the required starting torque Tm required for starting the engine, and is not actually used.
[0055]
SH ′ indicated by a solid line indicates that the field coil is operated in a state where the operating environment fluctuates to the high torque side. straight The torque-rotational speed characteristics when connected in a row are shown. The starting torque of the torque-rotational speed characteristic SH ′ becomes TH ′, and it is possible to greatly reduce excess torque that exceeds the necessary starting torque Tm required for engine starting.
[0056]
Thereby, the excessive starting torque can be reduced while maintaining the generated torque of the starter motor 21 at a level necessary and sufficient for starting the engine.
[0057]
SL indicated by a solid line indicates that the field coil is operated in a state where the operating environment fluctuates to the low torque side. common The torque-rotational speed characteristics when connected in a row are shown. The starting torque of the torque-rotation speed characteristic SL is TL, which is set higher than the necessary starting torque Tm necessary for starting the engine.
[0058]
With the operating environment fluctuating to the low torque side, straight When connected in a row, the starting torque is lower than the necessary starting torque Tm required for starting the engine, so that it is not actually used. In this case, the torque-rotational speed characteristic is not shown.
[0059]
That is, in FIG. 5, by limiting the armature current immediately after the engine 1 is started in a state where the operating environment has fluctuated to the high torque side, the originally excessive torque is reduced within a range that does not hinder the engine start. Thus, the various functions and effects described above can be achieved. Of course, in this case as well, the return from the parallel connection of the field coils to the serial connection can be performed in the middle of cranking, but this is not practical because the inductance of the field coils is large.
[0060]
The state where the operating environment fluctuates to the high torque side here refers to a state where the motor temperature is low and the battery output is high, and the state where the operating environment fluctuates to the low torque side means that the motor The temperature is high and the battery output is low. The detection of the battery output can be based on the battery voltage, for example. Of course, in this case as well, only the motor temperature or the battery output may be monitored to determine whether to switch the field coil.
[0061]
[Example 3]
Another embodiment of the starter 2 is shown in FIG.
[0062]
FIG. 6 shows an engine starting device, 21 is a starter motor composed of a DC series 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 short-circuit relay. . The starter motor 21 is formed by serially connecting field coils 214 and 215 and an armature coil (armature) 213 constituting a series wound field winding with an intermediate tap 10. When the pair of contacts of the short-circuit relay 9 is turned on, the field coil 214 is short-circuited.
[0063]
To explain the operation, 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 started with a high torque-rotational speed characteristic. In addition, the idle stop ECU 6 determines whether or not the engine can be automatically stopped and then automatically restarted based on an input signal from a sensor or the like, and energizes the magnet switch 22 to start the starter motor 21 with a low torque-rotation speed characteristic. To do.
[0064]
Further, when the idle stop ECU 6 determines that the operating environment has shifted the torque-rotational speed characteristic of the starter motor 21 to the high torque side by an external input, the idle stop ECU 6 closes the short-circuit relay 9 and then closes the magnet switch 22. As a result, the field coil 214 is short-circuited and the field magnetic flux of the starter motor 21 is greatly reduced, the torque-rotational speed characteristic is shifted to the low torque side, and engine start due to excessive torque can be avoided.
[0065]
A modification of the circuit of FIG. 6 is shown in FIG.
[0066]
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. When the engine automatic restart is determined, the idle stop ECU 6 closes the magnet switch 22 and activates the DC series motor 21.
[0067]
If it is determined that the driving environment has shifted the torque-rotation speed characteristic to the high torque side, the short-circuit transistor 90 is closed, and if it is not, the short-circuit transistor 90 is opened to achieve the above effect. it can.
[0068]
(Control mode)
Next, an example of a control operation at the time of engine automatic restart performed by the idle stop ECU 6 will be described below with reference to a flowchart shown in FIG.
[0069]
First, it is determined whether or not the engine is automatically stopped by the eco-run (100). If the engine is automatically stopped, it is determined whether or not the engine automatic restart condition is satisfied (102). Read from the ECU 7 or sensor (104).
[0070]
Next, it is determined whether or not the torque of the starter motor 21 is excessive based on the determination result of the operating environment (106). If it is determined that the torque is excessive, the torque-rotational speed characteristic of the starter motor 21 is reduced to the low torque side. (108). The shift of the torque-rotational speed characteristic may be performed using the method of each embodiment described above. The torque-rotational speed characteristic of the starter motor 21 is initially set on the high torque side.
[0071]
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 predetermined. It is determined that the torque is excessive when the threshold value is exceeded. That is, when the engine temperature detected by the radiator cooling water temperature is less than 0 ° C., it is considered that the lubricating oil viscosity of the engine 1 is high, and the required torque at the time of starting the engine is large. 5 When the temperature is below 0 ° C, it is considered that the torque generated by the motor has increased due to a decrease in the electric resistance of the motor winding. When the engine temperature is above 100 ° C, the viscosity of the lubricating oil is low and the lubricating oil escapes downward from the piston surface. Insufficient lubrication It is assumed that the required torque at the start of the engine increases due to increased friction at the start of the engine. That is, in this embodiment, when the engine temperature is 0 to 100 ° C., the motor temperature is 50 ° C. or less, and the battery voltage is equal to or higher than a predetermined threshold value, the torque excess side is determined.
[0072]
In addition, in the above, the logical product of each condition is used as the determination condition, but the logical sum of each condition may be used as the determination condition.
[0073]
In addition, when the battery temperature is detected and within a predetermined range, for example, 20 to 50 ° C., the torque excess side may be set. It is well known that battery output decreases at low and high temperatures.
[0074]
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 or not the torque is on the excessive side (high torque side) based on the state of a part or all of the motor temperature, the engine temperature, the battery voltage, and the battery temperature.
[0075]
Next, the magnet switch 22 is turned on (110) and waits until a predetermined time (at least during cranking) elapses (112). When the magnet switch 22 elapses, the torque-rotational speed characteristic of the starter motor 21 is returned to the high torque side (114). . Note that step 114 may be ignored if the torque-rotational speed characteristic is not shifted to the low torque side. Further, instead of waiting for a predetermined time in step 112, the torque-rotational speed characteristic may be returned to the high torque side when the engine rotational speed exceeds the predetermined rotational speed.
[0076]
Next, it waits until the engine speed exceeds a predetermined value (116), and when it exceeds, the starter 2 is returned to the initial state assuming that the engine start is completed (118).
[0077]
If it does in this way, the above-mentioned operation effect can be produced.
(Modification)
The torque-rotation speed characteristic of the starter motor 21 may be changed by another known method. The operation of removing the armature current limitation during cranking or switching the field coil in series is performed after a predetermined time from the start of energization. You may perform when exceeding a predetermined value. In the above embodiment, the automatic engine restart after the idle stop has been described. However, the engine may be manually started by turning on the ignition switch. In addition, two starters 2 may be provided, and both may be driven when high starting torque is required.
[0078]
Further, the torque-rotational speed characteristic may be freely changed according to the operating environment by, for example, PWM controlling the armature current of the starter motor. 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.
[0079]
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 return point of the torque-rotation speed characteristic to the high torque side during cranking. Also good. In addition, the magnitude and the waveform of the current supplied to the starter motor 21 may be directly monitored to adjust the magnitude to an appropriate level. Further, the return time point may be determined based on the increase rate of the engine speed. The motor temperature can also be estimated indirectly based on data such as the engine water temperature and the time elapsed since the previous start. After this returning operation, when it is determined that the current is excessive (torque is excessive), the torque-rotational speed characteristic may be shifted again to the low torque side. After the torque-rotation speed characteristic is shifted to the low torque side and starting is started, the torque-rotation speed characteristic may be returned to the original state if the increase rate of the engine speed is small. Of course, information from various sensors mounted on the vehicle can be used as the driving environment data. Of course, the starter 2 can be connected to the engine 1 through a torque transmission mechanism other than the belt / pulley mechanism.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing an engine start circuit system according to a first embodiment.
FIG. 2 is a circuit diagram showing the starter shown in FIG. 1;
3 is a torque-rotation speed characteristic diagram showing characteristics of the starter shown in FIG. 2; FIG.
FIG. 4 is a circuit diagram illustrating a starter according to a second embodiment.
FIG. 5 is a torque-rotational speed characteristic diagram showing characteristics of the starter shown in FIG. 4;
FIG. 6 is a circuit diagram illustrating a starter according to a third embodiment.
FIG. 7 is a circuit diagram showing a modification of the starter according to the third embodiment.
FIG. 8 is a flowchart showing an engine automatic restart control operation.
[Explanation of symbols]
1 engine
2 Starter
3 Belt
6 Idle stop ECU (control means)

Claims (3)

A starter motor for starting the engine;
Detecting means for detecting a physical quantity having a correlation with at least one of a motor temperature, an engine temperature, a battery temperature, a battery voltage, and a battery output and affecting the starting torque of the starter motor;
Torque control means for changing the torque- rotation speed characteristic of the starter motor based on the physical quantity;
With
The torque control means includes
When the physical quantity that is assumed that the starting torque exceeds a predetermined level is detected, the torque-rotational speed characteristic is changed to a low torque side, or the physical quantity that is assumed that the starting torque is lower than a predetermined level. If detected, the torque-rotational speed characteristic is changed to the high torque side ,
When the motor temperature is estimated to be below a predetermined level, the torque-rotational speed characteristic is changed to the low torque side ,
An engine starter characterized by changing the torque-rotational speed characteristic to a high torque side when the motor temperature is estimated to be equal to or higher than a predetermined level . A starter motor for starting the engine;
Detecting means for detecting a physical quantity affecting the starting torque of the starter motor;
Torque control means for changing a torque-rotation speed characteristic of the starter motor based on the physical quantity;
With
The torque control means includes
When the physical quantity that is assumed that the starting torque exceeds a predetermined level is detected, the torque-rotational speed characteristic is changed to a low torque side, or the physical quantity that is assumed that the starting torque is lower than a predetermined level. If detected, the torque-rotational speed characteristic is changed to the high torque side,
Based on the physical quantity detected before the engine is started, the torque-rotational speed characteristic is changed before the starter motor is started ,
Engine starting device, characterized in that that end Ryosu a shift to a low torque side of the torque-rotational speed characteristic before cranking completion of the engine. The engine starting device according to claim 2 ,
The torque control means includes
An engine starter that determines the end timing based on the detected state of the engine start system .

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