JP2003158830A - Idle stop type vehicle drive unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an idle stop type vehicle drive unit capable of improving engine start reliability with a simple structure. SOLUTION: If an engine start is difficult to be performed by driving a starter motor 4 from a low-voltage battery 3 through a first starting switch 7, the first starting switch 7 is turned off, and a second starting switch 8 is turned on to drive the starter motor 4. As a result, even if the capacity of the low-voltage battery 3 is low, the engine start becomes available, thus improving the engine restart reliability of an idle stop type vehicle which often stops an engine during running.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicular generator / motor device.

[0002]

2. Description of the Related Art There is known an idle stop type vehicle drive device for stopping an engine at a stop at an intersection or the like. As an example of this idle stop type vehicle drive device, a system in which a generator motor for transferring power to and from an engine and a starter motor (starter motor) for starting the engine are provided (hereinafter also referred to as a starter motor-generator motor IS device) ) Is known. In this system, a starter motor and its coupling type are designed in a structure that generates a large torque in the engine when the engine is running at a low speed, as in the normal system. Since it is possible to design a structure for driving an air conditioner) into a generator motor and its connection type, it is said that the entire system can be made smaller and lighter than in the case of performing all the above with a single generator motor.

In recent years, mainly to reduce the size of rotary electric machines and reduce resistance power consumption, high-voltage batteries (for example, 36 to 48 V) are used to supply power to large power loads, and small power loads such as control devices are supplied. A two-battery vehicle-mounted power supply device has been proposed in which power is supplied by a low-voltage battery (for example, 12V). In this two-battery vehicle-mounted power supply device, it is preferable that the high-voltage generator supply power to a large-capacity high-voltage battery, and the high-voltage battery transmits low-voltage power to a small-capacity low-voltage battery by a step-down DC-DC converter. .

In the case of combining the starting motor-generator motor type IS device and the two-battery type on-vehicle power supply device, a generator motor for driving a large on-vehicle load such as an air conditioner is driven almost all the time and is connected to a high voltage battery. It is considered preferable to supply power from a low voltage battery to a starter motor that is driven for a short time and is driven at a low speed (small back electromotive force) and a large current.

[0005]

However, in the combination of the starting motor-generator motor type IS device and the two-battery type on-vehicle power supply device described above, the low-voltage battery has a small remaining capacity or the low-voltage battery is defective. If this happens, the engine cannot be started even though the starter motor is energized from the low-voltage battery, and the stored power of the low-voltage battery is further consumed, which adversely affects the operation of the control device.

In this case, it is considered that the engine is driven by the generator motor, but for that purpose, it is necessary to design the generator motor to have a structure and a coupling system capable of outputting a low rotation speed and large torque. However, designing the generator motor with a low rotation speed and large torque output that enables engine start can cause the generated voltage of the generator motor to become extremely large and the battery to be overcharged during high-speed cruise, that is, when the engine speed is high. In order to prevent this, it is necessary to employ a field winding type synchronous machine with a complicated structure to perform demagnetization control, and in order to realize the above low rotation speed and large torque output characteristics, the size of the generator motor becomes significantly large. There was also the problem of being lost.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an idle stop type vehicle drive device which has improved engine starting reliability with a simple structure.

[0008]

An idle stop type vehicle drive apparatus of the first invention is an engine for running a vehicle, a starter motor for driving the engine, an AC generator / motor for exchanging power with the engine, and the AC. A bidirectional inverter for exchanging electric power with the generator motor, a high voltage battery for exchanging high voltage electric power with the bidirectional inverter, a low voltage battery for supplying low voltage electric power for starting the engine to the starter motor, and the starter motor A first start switch provided between the low voltage battery, a second start switch provided between the starter motor and the high voltage battery, and a low capacity of the low voltage battery when starting the engine. If determined or if the start of the engine by the power of the low voltage battery fails,
Switch selecting means for turning off the first start switch and driving the second start switch to drive the starter motor by the electric power of the high voltage battery.

That is, according to the present invention, when the capacity of the low-voltage battery is insufficient, the starter motor is driven again from the high-voltage battery instead of the low-voltage battery before the engine is started or based on the failure of the engine start. Even when the engine is started, the engine can be started, and the reliability of starting the engine can be improved. Originally, driving a starter motor that can be driven by a low-voltage battery by a high-voltage battery does not hinder the engine starting itself, although the torque and heat generation of the starter motor increase.

Thus, the generator motor can be optimally designed so that the generated voltage is optimal for battery charging at least during the high speed cruising at least during the idle period of the engine, so that the generator motor is not unnecessarily increased in size. The redundancy of starting the engine can be improved.

An idle stop type vehicle drive device of a second invention is an engine for driving a vehicle, a starter motor for driving the engine, an AC generator motor for exchanging power with the engine, and an exchange of electric power with the AC generator motor. Between the bidirectional inverter, a high voltage battery for exchanging high voltage power with the bidirectional inverter, a low voltage battery for supplying low voltage power for starting the engine to the starter motor, and between the starter motor and the low voltage battery A first start switch disposed between the two batteries, a DC-DC converter interposed between the batteries to control power transmission from at least the high-voltage battery to the low-voltage battery, and the low-voltage battery has a capacity when starting the engine. When it is determined that there is a shortage, at the same time as turning on the first start switch or prior to it. By driving the DC-DC converter is characterized in that the power transmission from the high voltage battery to the low voltage battery.

That is, according to the present invention, the DC-
Power is transmitted from the high-voltage battery to the low-voltage battery through the DC converter, so engine start can be realized regardless of the low-voltage battery capacity shortage, and even if the low-voltage battery capacity is sufficient, the starter motor will eventually be powered by both batteries. Therefore, the starting current that the low-voltage battery bears can be reduced, and the effects of increasing the battery life, suppressing a drop in the power supply voltage applied to the low-voltage electric load connected to the low-voltage battery, and the like can be achieved.

When the capacity of the low-voltage battery is seriously insufficient, the low-voltage battery may absorb the current transmitted by the high-voltage battery to prevent the engine from starting.
Such a case is extremely rare, because the DC converter is normally operated when the voltage of the low voltage battery falls below a predetermined value. In other words, according to the present invention, if the DC-DC converter eventually needs to transmit the amount of power for engine starting lost by the low-voltage battery from the high-voltage battery to the low-voltage battery, this power transmission can be performed simultaneously with or before the engine start. Then, the capacity of the low-voltage battery is reduced by starting the engine and the loss caused by charging and discharging the low-voltage battery is minimized.

The present invention may be carried out only when it is determined that the low voltage battery is insufficient in capacity when the engine is started.

Accordingly, the generator motor can be optimally designed so that the generated voltage is optimal for battery charging at least during high-speed cruising at least during the idle period of the engine, so that the generator motor is not unnecessarily increased in size. The redundancy of starting the engine can be improved.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The preferred embodiments of the present invention will be described with reference to the following examples.

[0017]

[Embodiment 1] (Overall Configuration) FIG. 1 is a block circuit diagram showing an idle stop type vehicle drive apparatus of this embodiment.

1 is an engine, 2 is a high voltage battery, 3 is a low voltage battery, 4 is a starter motor, 5 is a generator motor consisting of a three-phase synchronous machine, 6 is a three-phase inverter, 7 is a first start switch, and 8 is a second. Start switch, 9 is a controller, 1
Reference numeral 0 is a DC-DC converter, and 11 is a belt.

The high-voltage battery 2 is connected to the three-phase inverter 6 through the high-voltage power supply line LH, and the three-phase inverter 6 performs orthogonal bidirectional power conversion between the high-voltage battery 2 and the generator motor 5. The low voltage battery 3 supplies power to the starter motor 4 through the first start switch 7 and also supplies and receives power to and from a low voltage electric load (not shown) through the low voltage power supply line LL. The second starting switch 8 is a high voltage power line L
H is connected to the high potential side power input terminal of the starter motor 4. The controller 9 controls the first starting switch 7, the second starting switch 8, the three-phase inverter 6, and the DC-DC converter 10. The DC-DC converter 10 is
It is connected to the three-phase inverter 6 through the high-voltage power supply line LH, and the three-phase inverter 6 includes the high-voltage battery 2 and the generator motor 5.
Performs orthogonal bidirectional power conversion between and. The belt 11 connects the generator motor 5 and the crankshaft pulley with each other.
Reference numeral 12 denotes an electromagnetic clutch that connects the engine 1 and the crankshaft pulley, and the electromagnetic clutch 12 is controlled by the controller 9. The belt 11 also drives various auxiliary machines (not shown).

(Basic Operation) The basic operation of the above apparatus will be briefly described below.

When the engine is started, the controller 9 turns on the first start switch 7 to supply power to the starter motor 4 from the low voltage battery 3 and drive the starter motor 4 to start the engine 1.

The controller 9 monitors the voltage of the low voltage battery 3 and drives the DC-DC converter 10 so that the voltage value of the low voltage battery 3 is maintained within a predetermined range.

The generator motor 5 is driven by the engine 1 during traveling to generate electric power, and charges the high voltage battery 2 through the three-phase inverter 6 which substantially rectifies. The controller 9 monitors the voltage of the high-voltage battery 2, and adjusts the generated current by adjusting the phase of the three-phase exciting current flowing through the three-phase armature winding of the generator motor 5 through the three-phase inverter according to the voltage. To do. When the generator motor 5 is of the field winding type, it is natural to control the field current flowing through the field winding instead of the phase control (demagnetization control) of the three-phase excitation current.

The controller 9 releases the electromagnetic clutch 12 when it is necessary to drive an auxiliary machine (not shown) when the engine is stopped by the idle stop, and the generator motor 5 is driven.
Is driven to drive an auxiliary machine (not shown) by the generator motor 5 through the belt 11.

(Emergency Engine Starting Operation 1) Next, the emergency engine starting operation which characterizes this embodiment will be described below.

The controller 9 determines whether or not a cell starter switch (not shown) is turned on (S10).
0) When turned on, the first starting switch 7 is turned on to supply power from the low voltage battery 3 to the starter motor 4 to start the engine. A predetermined time after the first start switch 7 is turned on, it is determined whether the engine start is completed (S1
02), if completed, the first start switch 7 is cut off to end the routine, and if engine start by the starter motor 4 has failed, the three-phase inverter 6 is controlled to electrically operate the generator motor 5, Turn on the electromagnetic clutch 12,
The engine is started by the generator motor 5 (S10
4). After a predetermined time from the start of the electric operation of the generator motor 5, it is determined whether the engine start is completed (S106),
If completed, stop the electric operation of the generator motor 5 (S
108), the routine is ended, and if the engine start by the generator motor 5 has failed, the first start switch 7 is turned off (S110), the second start switch 8 is turned on (S112), and the high voltage battery is turned on. The starter motor 4 is strongly driven by the power supply 2 to start the engine, and a predetermined time after the second start switch 8 is turned on, it is determined whether the engine start is completed (S114). The second start switch 8 is cut off (S116) to end the routine, and if not completed, an engine start failure warning is issued (S118) and the routine ends.

In the above description, the completion of the engine start can be easily confirmed by a signal such as the engine speed as in the conventional case, and therefore the detailed description thereof will be omitted.

(Modification) In the above, the generator motor 5
It is possible to omit the engine starting by. When an engine command is input to the controller 9, the controller 9
If the voltage of the low voltage battery 3 is abnormally low before turning on the first start switch 7, the engine start may be immediately started by the generator motor 5 or the second start switch 8 may be started.

[0029]

Second Embodiment Another embodiment will be described below with reference to FIG.

In this embodiment, the second starting switch 8 shown in FIG. 1 is omitted.

Instead, the first starting switch 7 is turned on to supply electric power from the low voltage battery 3 to the starter motor 4 to start the engine, and at the same time or in advance thereof, D
By operating the C-DC converter 10, the voltage drop of the low voltage battery 3 due to the driving of the starter motor 4 that occurs simultaneously or immediately after is minimized. In this way, the starter motor 4 is essentially the two batteries 2, 3
This is very convenient because the burden current per battery is reduced, the voltage drop and power loss due to the internal resistance of the battery are reduced, and the battery life can be extended.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of an idle stop type vehicle drive device of the present invention.

FIG. 2 is a flowchart showing a control operation of the apparatus of FIG.

FIG. 3 is a circuit diagram showing a second embodiment of an idle stop type vehicle drive device of the present invention.

[Explanation of symbols]

1 engine 2 high voltage battery 3 low voltage battery 4 Starter motor 5 Generator motor (AC generator motor) 6 three-phase inverter 7 First start switch 8 Second start switch 9 controller (switch selection means) 10 DC-DC converter

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) F02N 11/08 F02N 11/08 L 15/00 15/00 E (72) Inventor Hirofumi Kako Kariya city, Aichi prefecture 1-chome, Showa-cho, DENSO Co., Ltd. (72) Inventor Yoshitaka Kiuchi 1-1-chome, Showa-cho, Kariya City, Aichi F-term in DENSO, a stock company (reference) GA01 HF02Z HF19Z 3G093 AA01 AA16 BA21 BA22 CA01 DA12 DB19 DB25 EB00 EC02 FA12 5G060 BA08 DA03 DB08 DB09

Claims (2)

[Claims] 1. A vehicle running engine, a starter motor for driving the engine, an AC generator motor for transferring power to and from the engine, a bidirectional inverter for transferring power to and from the AC generator motor, and the bidirectional inverter. A high-voltage battery that exchanges high-voltage power, a low-voltage battery for supplying low-voltage power for starting the engine to the starter motor, and a first start switch provided between the starter motor and the low-voltage battery. A second start switch provided between the starter motor and the high-voltage battery, and when the low-voltage battery is judged to have insufficient capacity at the time of starting the engine, or when the engine starts due to the electric power of the low-voltage battery. The first start switch is turned off and the second start switch is driven to drive the high voltage battery. Idling stop vehicle driving apparatus characterized by having a switch selecting means for driving the starter motor by the power of. 2. An engine for running a vehicle, a starter motor for driving the engine, an AC generator motor for transferring power to and from the engine, a bidirectional inverter for transferring power to and from the AC generator motor, and the bidirectional inverter. A high-voltage battery that exchanges high-voltage power, a low-voltage battery for supplying low-voltage power for starting the engine to the starter motor, and a first start switch provided between the starter motor and the low-voltage battery. , A DC-D that is interposed between the both batteries and controls power transmission from at least the high-voltage battery to the low-voltage battery
A C converter, and an idle stop characterized in that, at the time of starting the engine, the DC-DC converter is driven at the same time as or prior to turning on the first start switch to transmit power from the high voltage battery to the low voltage battery. Vehicle drive system.