WO2013080746A1

WO2013080746A1 - Engine starting device and starting method

Info

Publication number: WO2013080746A1
Application number: PCT/JP2012/078560
Authority: WO
Inventors: 宏泰城吉; 西岡　明; 義秋長澤
Original assignee: 日立オートモティブシステムズ株式会社
Priority date: 2011-11-29
Filing date: 2012-11-05
Publication date: 2013-06-06
Also published as: CN103946537B; JP5761717B2; JP2013113228A; CN103946537A

Abstract

Provided are an engine starting device and a starting method by means of which it is possible to restart an engine as quickly as possible within the allowable range for decreases in battery voltage. A rotation detection sensor (110) detects the rotation speed of a DC motor (105). A control means (109) performs a PWM control for electrification of the DC motor. The control means (109) continuously changes the current-carrying rate (D) of the PWM control on the basis of the rotation speed of the DC motor detected by the rotation detection sensor (110) so that the electric current flowing to the DC motor stays at a preset constant value. Thus, the battery electric current from the start of motor electrification to the completion of engine starting is held at a constant value, said value being a nearly constant electric current value, which is within the allowable battery voltage range and near the allowable value.

Description

Engine starting device and starting method

The present invention relates to an engine starting device and a starting method for starting an engine using a DC motor, and more particularly to an engine starting device and a starting method suitable for restarting an engine with an idle stop system.

Recently, some automobiles are equipped with an idle stop system that temporarily stops the engine when a predetermined condition is satisfied during operation for the purpose of saving energy resources and protecting the environment. This idle stop system automatically stops the engine when the driver stops the vehicle, for example, when waiting for a signal, and then the driver needs to be restarted or the engine needs to be operated. The engine is automatically restarted when When restarting the engine, a so-called pinion extrusion type starter motor is used, and at the start, the pinion is pushed out and meshed with a ring gear directly connected to the engine shaft, and the engine is started by cranking by the starter motor. .

When starting the engine, it is known that a current flows through the battery by energizing the starter motor, and the voltage drops corresponding to the current due to the characteristics of the battery. In an idle stop system that frequently restarts the engine even during operation, an electrical component such as a car navigation system is reset when the voltage decreases. For this reason, a vehicle equipped with a conventional idle stop system is supported by an auxiliary power source or the like, but this leads to deterioration in mountability and cost increase.

On the other hand, conventionally, a resistor is added to the circuit to reduce the inrush current and suppress the battery voltage drop at the start of the engine start, and then the resistor is short-circuited to pass the current and secure the cranking torque. (For example, refer to Patent Document 1).

As another example, when the engine is restarted, the energization of the motor is controlled by the switching element, and the duty ratio is gradually increased by the PWM control to increase the applied voltage of the motor. What is prevented is known (for example, see Patent Document 2).

JP 2004-308645 A JP 2010-106825 A

However, in Patent Document 1 and Patent Document 2, since the battery current is controlled so as to decrease with time, the output torque of the starter motor decreases, engine cranking cannot be performed sufficiently, and engine restart is not possible. It may take a long time to start.

An object of the present invention is to provide an engine starter and a start method that can restart an engine as quickly as possible within an allowable range of a battery voltage drop.

(1) In order to achieve the above object, the present invention provides an engine starter for transmitting the rotational force of a direct current motor to the engine to start the engine, and a rotational speed detecting means for detecting the rotational speed of the direct current motor. And a control means for PWM-controlling energization to the DC motor, the control means preliminarily receiving a current flowing through the DC motor based on the rotational speed of the DC motor detected by the rotational speed detection means. The energization ratio of the PWM control is continuously changed so that the set constant value is obtained, so that the battery current is allowed to be a substantially constant set current value from the start of motor energization to the completion of engine start. The value is kept within a range and a constant value close to the allowable value.
With this configuration, the engine can be restarted as quickly as possible within the allowable range of the battery voltage drop.

(2) In the above (1), preferably, the control means energizes using the fact that the current flowing to the DC motor can be approximated to be proportional to the square of the energization ratio when the energization to the DC motor is PWM controlled. The ratio is determined.

(3) In the above (1), preferably, the rotational speed detection means of the direct current motor detects the rotational speed of the direct current motor indirectly using the rotational speed of the engine.

(4) In the above (3), preferably, the control means is configured such that the rotational speed of the DC motor detected by indirectly using the rotational speed of the engine deviates from the actual rotational speed of the DC motor. The control means is configured to determine that the rotational speed of the DC motor detected by the determination means indirectly using the rotational speed of the engine is the actual rotational speed of the DC motor. When it is determined that there is a divergence, the actual rotational speed of the DC motor is estimated and used for calculation for determining the energization ratio of the PWM control.

(5) In the above (1), preferably, the control means, based on a current flowing in an electric device that uses the battery as a power source other than the DC motor, totals a current flowing in a battery serving as a power source of the vehicle. The current supplied to the DC motor is changed so as to have a predetermined value, and the energization ratio of the PWM control is determined.

(6) In order to achieve the above object, the present invention relates to an engine starting method for starting the engine by transmitting the rotational force of the DC motor to the engine, the rotation of the DC motor detected by the rotational speed detecting means. Based on the number, the energization ratio of the PWM control is continuously changed so that the current flowing through the DC motor becomes a predetermined constant value. Here, from the start of energization of the motor to the completion of engine start. The inter-cell battery current is set to a substantially constant current value, and the battery voltage is also kept within a permissible range and to a constant value close to the permissible value.
With this method, the engine can be restarted as quickly as possible within the allowable range of the battery voltage drop.

According to the present invention, the engine can be restarted as quickly as possible within the allowable range of the battery voltage drop.

It is a lineblock diagram of the engine starting device by one embodiment of the present invention. It is explanatory drawing of the energization signal of PWM control used for the engine starting apparatus by one Embodiment of this invention. It is explanatory drawing of the determination method of the electricity supply ratio D in the engine starting apparatus by one Embodiment of this invention. It is a flowchart which shows the content of the starting method of the engine in the engine starting apparatus by one Embodiment of this invention. 5 is a flowchart showing the contents of a method for estimating the rotational speed of a motor in an engine starter according to an embodiment of the present invention. It is a wave form diagram showing an example of the control state in the engine starting device by one embodiment of the present invention. It is explanatory drawing of the other determination method of the electricity supply ratio D in the engine starting apparatus by one Embodiment of this invention.

Hereinafter, the configuration and operation of an engine starter according to an embodiment of the present invention will be described with reference to FIGS.
First, the configuration of the engine starter according to the present embodiment will be described with reference to FIG.

FIG. 1 is a configuration diagram of an engine starter according to an embodiment of the present invention.

As shown in FIG. 1, the starter 101 is roughly composed of a magnet switch 102, a pinion gear 103, and a motor 105. The motor 105 is a so-called DC motor, and a rotational driving force is generated by applying a DC voltage. The pinion gear 103 moves on the motor rotation shaft when the magnet switch 102 pulls the lever when necessary, and meshes with the ring gear 104 directly connected to the engine shaft. If the pinion gear 103 and the ring gear 104 are engaged, the motor 105 is rotated by energizing the motor 105, and the rotational force of the motor 105 is transmitted to the ring gear 104 through the pinion gear 108 to rotate the engine.

The control device 109 controls the idle stop based on various information such as the brake pedal state and the vehicle speed in addition to the normal fuel injection, ignition and air control (electronic control throttle).

The motor rotation detection sensor 110 detects the rotation of the motor. Information on the detected motor rotation speed is input to the control device 109. Instead of directly detecting the rotation of the motor with a sensor, the engine rotation detection sensor 110A may be used to indirectly detect the rotation speed of the motor using the engine rotation.

The magnet switch 105 is controlled by the control device 109 via the switch 106. For example, a mechanical relay switch can be used as the switch 106. The energization of the motor 105 is also controlled by the control device 109 via the switching element 107. As the switching element 107, for example, a switching element using a semiconductor such as a MOSFET can be used.

Next, with reference to FIG. 2, the energization signal for PWM control used in the engine starter according to the present embodiment will be described.
FIG. 2 is an explanatory diagram of energization signals for PWM control used in the engine starter according to one embodiment of the present invention.

The control device 109 outputs the PWM signal shown in FIG. 2 as an energization signal.

T shown in FIG. 2 is the length of one cycle of PWM control. For example, when the frequency of PWM control is set to 10 KHz, T is 0.1 ms. In this embodiment, the frequency of PWM control is determined so as to be sufficiently faster than the electric time constant of the motor.

TON shown in FIG. 2 is a section in which power is supplied to the motor in one cycle. The energization ratio D is defined as the ratio of the energized section in one cycle as in the following equation (1).

Here, D: energization ratio in PWM control, TON: section [s] where the motor is energized in one period, and T: period length [s].

The energization ratio D is a variable that can be changed between 0.0 and 1.0. The control device 109 controls the energization amount to the motor by changing the energization ratio D.

Next, a method for determining the energization ratio D in the engine starter according to the present embodiment will be described with reference to FIG.
FIG. 3 is an explanatory diagram of a method for determining the energization ratio D in the engine starter according to the embodiment of the present invention.

Fig. 3 shows a simple circuit diagram of the battery and starter. The battery 301 has an internal resistance Rb, and assuming that the initial voltage of the battery is V0, the output voltage Vb of the battery is determined by the following equation (2).

Here, Vb: battery output voltage [V], V0: initial voltage of the battery (voltage when no current flows) [V], Ib: current flowing through the battery [A], Rb: internal resistance of the battery [ Ω].

As can be seen from Equation (2), the battery voltage is determined by the battery current, and if the current can be controlled to a predetermined value, the battery voltage can also be controlled to the predetermined value. Similarly, in the motor unit 302 of FIG. 3, the battery voltage Vb can be expressed by the following expression (3) when wiring, motor internal resistance, switching element resistance, and the like are collectively set as the motor resistance Rm.

Where Vb: battery output voltage [V], Ib: current flowing through the battery [A], Rm: motor resistance (including wiring resistance, internal resistance, switching element resistance) [Ω], Ve: motor rotation Are the counter electromotive voltage [V], ke: motor counter electromotive voltage coefficient [V / rpm], and Nm: motor rotation speed [rpm].

Here, the relationship of the following equation (4) is obtained from the equations (2) and (3).

As can be seen from equation (4), in general, in a DC motor, when the rotational speed Nm is 0, that is, when the energization starts, the current flows most, and when the rotational speed increases, the current decreases. It has been.

Here, in order to control the current to be constant by changing the energization ratio D of the PWM control, the inventors have found that the current can be approximated to the energization ratio by the following equation.

As can be seen from Equation (5), in this embodiment, the current Ib flowing through the battery in the PWM control is proportional to the square of the energization ratio D. In the configuration shown in FIG. 3, since the motor current Im flowing through the motor 302 is equal to the battery current Ib, the current Im flowing through the motor is proportional to the square of the energization ratio D when the energization to the DC motor is PWM controlled. Then it can be approximated. This relationship was theoretically determined through experimental observations by the inventors. However, the equation (5) is an approximation that is established only in a range in which one cycle of PWM can be regarded as being sufficiently fast with respect to the electric time constant of the motor. Indicates that it is determined by a variable. To reversely use this relationship and determine the energization ratio D so that the predetermined battery current Ib is obtained, the equation (5) is transformed into the following equation (6).

According to Equation (6), in the present embodiment, the battery current Ib is set to a predetermined value, and the energization ratio D is continuously determined based on the motor rotation speed Nm. However, when the energization ratio D calculated by the equation (6) exceeds 1.0, the energization ratio is set to 1.0. When incorporating into an actual system, first, an allowable battery current is determined in advance using Equation (2) based on the allowable value of the battery voltage drop. The allowable minimum voltage of the battery is set to 10.5V, for example. Then, a variable other than the motor rotational speed Nm in equation (6) including the battery current value is measured in advance and stored in the control device 109 in advance.

Next, the engine starting method in the engine starting apparatus according to the present embodiment will be described with reference to FIG.
FIG. 4 is a flowchart showing the contents of the engine starting method in the engine starting device according to the embodiment of the present invention.

As shown in FIG. 4, when an engine restart request is generated, in step 401, the control device 109 shown in FIG. 1 connects the starter and the engine. In the case of the pinion extrusion method, the pinion 103 in FIG. 1 is pushed out and meshed with the ring gear 104 directly connected to the engine. If the starter and the engine are in the connected state during the idle stop, and the starter and the engine are already in the connected state when the restart request is generated, step 401 is not necessary.

Next, in step 402, the control device 109 calculates the energization ratio D of the PWM control by the equation (6) using the variable stored in advance and the rotation speed Nm of the motor, and the waveform of the PWM control. Is output. Current starts to flow to the motor by PWM control, and the torque of the motor is transmitted to the engine to start rotation.

Then, the control device 109 continues the calculation in step 402 until the engine start completion condition shown in step 403 is satisfied. The engine start completion condition in step 403 can be determined to be that the engine start has been completed, for example, when the engine rotation has reached a predetermined rotation speed or higher. Until the engine start is completed, the control device 109 detects the motor speed at a constant interval (for example, 2 ms), calculates the energization ratio D, and updates the output. In this way, the battery current is substantially constant from the start of motor energization to the completion of engine start, and thus the set current value. Therefore, the battery voltage is also substantially constant, and the value is within the allowable range and close to the allowable value.

Since the starter and the engine are connected to transmit the rotational force of the motor to the engine until the restart is completed, the motor rotational speed can be indirectly obtained from the engine rotational speed.

After step 401 in FIG. 4, that is, if the starter and the engine are in a connected state, the rotational speed of the motor can be indirectly calculated from the rotational speed of the engine. As shown in FIG. 1, an engine rotation detection sensor 110A that detects the engine speed is provided. Many automobiles are equipped with an engine rotation detection sensor 110A. Therefore, the motor rotation detection sensor 110 is newly installed by calculating the rotation speed of the starter motor indirectly from the detected engine rotation speed. This is no longer necessary, leading to cost reduction. When calculating the motor speed of the starter from the engine speed, for example, the following equation (7) can be used.

Here, Nm: motor rotation speed [rpm], Ne: engine rotation speed [rpm], g: rotation speed conversion coefficient.

The rotational speed conversion coefficient g in Equation (7) can be obtained from the gear ratio between the engine and the motor. Specifically, when connected by a pinion and ring gear, in addition to the gear ratio determined by the number of teeth of the pinion and ring gear, when a reduction mechanism is provided between the motor and the pinion inside the starter, it depends on the reduction ratio of the reduction mechanism. The rotation speed conversion coefficient g can be obtained. The rotational speed conversion coefficient is stored in the control device 109 in advance, and is converted into the motor rotational speed Nm in the control device 109 based on the detected engine rotational speed Ne.

Many starters are provided with a one-way clutch while transmitting torque from the motor to the engine, and transmit torque only from the starter side. Since the clutch is disconnected when the engine starts combustion and the rotation speed becomes faster than the rotation by the starter, the starter rotation speed calculated from the engine rotation speed at this time does not match the actual starter rotation speed.

Here, a method for estimating the motor rotation speed when a difference occurs between the calculated value and the actual motor rotation speed when the motor rotation speed is calculated indirectly from the engine rotation speed will be described.

Many starters are provided with a one-way clutch 108 while transmitting torque from the motor to the engine, and transmit torque only from the starter side. In other words, the engine can be rotated by the rotational force of the motor, but the engine does not rotate the motor. Therefore, the motor speed calculated indirectly from the engine speed is higher than the actual motor speed. May show. At that time, the motor rotation speed is estimated.

Here, the method for estimating the rotational speed of the motor in the engine starter according to the present embodiment will be described with reference to FIG.
FIG. 5 is a flowchart showing the contents of the method for estimating the rotational speed of the motor in the engine starting device according to the embodiment of the present invention.

When the engine speed jumps due to combustion, the clutch is disconnected, and it is assumed that the motor that has become almost unloaded increases in speed with a constant inclination. On the other hand, by setting an upper limit for the increase in the rotation speed for each control cycle, the motor rotation speed is estimated for a sudden increase in engine rotation.

Here, the energization ratio D is calculated using Nm_out, where Nm_out is the estimated rotation speed with respect to the detected rotation speed Nm of the motor. This is repeated for each control cycle, and the calculation result before one control cycle is stored in the control device as Nm_outt-1. Further, ΔN is set in advance as the upper limit of the increase in the motor rotation speed for each control cycle.

In step 501, the control device 109 in FIG. 1 adds the upper limit value ΔN to the estimated motor rotation speed Nm_out−1 to obtain a new estimated motor rotation speed Nm ′. The newly estimated motor rotational speed Nm ′ is considered to be the maximum value that can increase within one control period with respect to the motor rotational speed Nm_outt−1 one period before.

Next, at step 502, the control device 109 compares the detected motor rotation speeds Nm and Nm ′ to determine whether or not a deviation from the actual motor rotation speed has occurred.

If it is determined in step 502 that the determination unit 109A of FIG. 1 does not satisfy Nm ≧ Nm ′, it is determined that there is no difference between the detected value and the actual motor speed, and in step 504, the control device 109 Is used to calculate the energization ratio D by substituting the detected rotational speed Nm as it is for Nm_out.

In Step 502, if Nm ≧ Nm ′, it is determined that there is a difference between the detected value and the actual motor speed. In this case, in step 503, the control device 109 substitutes Nm ′ for Nm_out and uses it for calculation of the energization ratio D.

In this way, when the motor rotational speed is obtained indirectly from the engine rotational speed, the energization ratio D can be calculated correctly even if a deviation from the actual motor rotational speed occurs.

Next, an example of a control state in the engine starter according to the present embodiment will be described with reference to FIG.
FIG. 6 is a waveform diagram showing an example of a control state in the engine starting device according to the embodiment of the present invention.

FIG. 6 shows the engine speed, the energization ratio D output from the control device 109, and the changes in the battery voltage and battery current at the time when the engine starting device of the present embodiment is implemented.

In this example, the energization ratio is calculated using only the engine speed. Since the motor rotational speed is detected indirectly from the engine rotational speed, a section where the estimated motor rotational speed is different from the actual speed and the motor rotational speed is estimated is indicated by a dotted line 603. The estimated motor rotational speed 603 indicates a value obtained by converting the rotational speed of the motor into the rotational speed on the engine shaft with the gear ratio of the motor and the engine. As shown by the battery current 605 at the time of energization, it is almost flat from the start of energization and is kept constant, and is almost in accordance with the set battery current. It can be seen that the battery voltage 604 at the time of energization was also leveled off and the engine was restarted without falling below the allowable minimum voltage.

Next, another method for determining the energization ratio D in the engine starter according to the present embodiment will be described with reference to FIG.
FIG. 7 is an explanatory diagram of another method for determining the energization ratio D in the engine starting device according to the embodiment of the present invention.

Here, a method for appropriately changing the current flowing through the motor in accordance with the power demand of equipment other than the starter motor will be described. Up to now, as shown in the simplified circuit diagram of FIG. 3, the explanation has been made on the assumption that almost all of the current flowing from the battery flows to the motor. However, in actual vehicles, there are electrical devices that carry current in addition to the starter motor. To do.

FIG. 7 shows a simple circuit diagram in the case where there are electrical devices other than the starter. Assuming that the current flowing through the battery 301 is Ib, the current flowing through the motor of the starter 302 is Im, and the current flowing through the electric device 303 other than the motor is Ie, the relationship shown in the following equation (8) is established.

Here, Ib: current flowing through the battery, Im: current flowing through the motor, and Ie: total current flowing through the electrical equipment other than the motor.

As shown in the equation (8), the current Ib flowing through the battery is the sum of the current Im flowing through the motor and the current Ie flowing through the electric device other than the motor. Therefore, from the allowable battery current, the current Ie of the electric device other than the motor. By setting the value obtained by subtracting as the motor current, the battery current is kept constant and allowed to be maintained as a total value. The current Ie flowing through the electrical equipment other than the motor is configured to be recognized directly or indirectly. For example, the current Ie flowing through an electrical device other than a motor is directly measured by a current sensor, or the current normally used by each electrical device other than a motor is individually stored in advance in the control device and used by the electrical device. In the case where the stored current flows, the current flowing indirectly through the electric device other than the motor may be calculated. At this time, the following equation (9) for calculating the energization ratio D to the motor is used.

Even if the current Ie flowing through the electrical equipment other than the motor changes, the current Im flowing through the motor is determined using the equation (8), and the energization ratio D to the motor is calculated using the equation (9). The engine can be kept constant, and the engine can be restarted as quickly as possible while keeping the voltage drop of the battery within an allowable range.

As described above, according to the present embodiment, the battery voltage can be kept substantially constant by determining the energization ratio based on the motor speed and keeping the motor current at an almost constant arbitrary value. By doing so, the battery voltage does not fall below the allowable value when the engine is restarted, and the engine is restarted as quickly as possible.

Also, when calculating the motor speed indirectly from the engine speed, it is not necessary to attach a rotation detection sensor to the starter, leading to cost reduction.

In addition, when detecting the current flowing in electrical equipment that uses a battery as a power source other than the motor and controlling the motor so that the battery current remains constant, the battery voltage drops even if a large current flows in equipment other than the motor. It can be suppressed within an allowable range.

DESCRIPTION OF SYMBOLS 101 ... Starter body 102 ... Magnet switch 103 ... Pinion 104 ... Ring gear 105 ... DC motor 106 ... Switch for energizing magnet switch 107 ... Switching element 108 for energizing motor ... One-

way clutch

109, 109A ...

Control device

110, 110A ... Rotation detection sensor

Claims

An engine starter that transmits the rotational force of a DC motor to the engine to start the engine,
A rotational speed detection means for detecting the rotational speed of the DC motor;
Control means for PWM control of energization to the DC motor,
The control means continuously sets the energization ratio of the PWM control based on the rotation speed of the DC motor detected by the rotation speed detection means so that the current flowing through the DC motor becomes a predetermined constant value. Change to
As a result, the battery current is set to a substantially constant current value from the start of energization of the motor to the completion of engine start, and the battery voltage is also kept within a permissible range and close to a permissible value. apparatus.
The engine starter according to claim 1, wherein
The control means determines an energization ratio using the fact that the current flowing to the DC motor can be approximated to be proportional to the square of the energization ratio when the energization to the DC motor is PWM-controlled. .
The engine starter according to claim 1, wherein
The engine starter characterized in that the DC motor rotation speed detecting means indirectly detects the rotation speed of the DC motor by indirectly using the rotation speed of the engine.
The engine starter according to claim 3,
The control means comprises a judging means for judging that the rotational speed of the DC motor detected by indirectly utilizing the rotational speed of the engine deviates from the actual rotational speed of the DC motor,
When the determination means determines that the rotational speed of the DC motor detected indirectly by using the rotational speed of the engine has deviated from the actual rotational speed of the DC motor. Is an engine starter characterized in that it estimates the actual rotational speed of the DC motor and uses it for the calculation for determining the energization ratio of the PWM control.
The engine starter according to claim 1, wherein
The control means controls the direct current motor so that the current flowing through the battery serving as the power source of the vehicle becomes a predetermined value based on the current flowing through the electric equipment using the battery as a power source other than the direct current motor. An engine starter characterized in that a current to be supplied is changed to determine an energization ratio of the PWM control.
An engine starting method for transmitting the rotational force of a DC motor to the engine and starting the engine,
Based on the rotational speed of the DC motor detected by the rotational speed detection means, the energization ratio of the PWM control is continuously changed so that the current flowing through the DC motor becomes a predetermined constant value.
Here, the battery current is set to a substantially constant current value from the start of motor energization to the completion of the engine start, and the battery voltage is also kept within a permissible range and close to a permissible value. Method.