JP4541719B2 - Vehicle power supply - Google Patents

Description

  The present invention relates to a power supply device for a vehicle having two voltage systems.

  In recent years, in vehicles such as automobiles that use an engine as a drive source, it has been required to increase the battery voltage for the purpose of reducing the size and weight of electrical components, improving efficiency, improving fuel efficiency, and reducing exhaust gas. Yes. When this battery voltage is increased, consideration must be given to the compatibility and durability of in-vehicle electrical components with conventional products. Therefore, in practice, the conventional low voltage system and high voltage A dual power supply system with a grid is embodied.

The voltage system of this dual power supply system is generally provided with a 42V voltage system as a high-voltage voltage system as compared with the conventional 14V voltage system, as disclosed in Patent Document 1, for example. In Patent Document 1, a DC-DC converter for stepping down a 42V output from a generator and supplying it to a conventional 14V load is provided as a voltage controller for a 42V output AC generator without being provided separately from the generator. A function for generating a voltage of 14 V corresponding to a conventional load is incorporated.
JP 2002-95177 A

  By the way, in the vehicle which uses an engine as a drive source, what equips an exhaust system with the electric heating catalyst for the purpose of exhaust gas purification at the time of engine starting is known. This electric heating catalyst is intended to activate the catalyst early by supplying power from a battery in advance and heating the catalyst before starting the engine.

  When electric power is supplied to this electric heating catalyst, in a vehicle of a dual power supply system, electric power is supplied from only one power source or from both power sources. This not only greatly affects the power supply to the device, but the power supply becomes unstable, and there is a risk that activation is delayed because the catalyst is not sufficiently heated.

  Such a problem can be avoided by increasing the power supply capacity. However, in-vehicle electric loads that require a large amount of power include various types of loads in addition to the electric heating catalyst. Increasing the capacity will unnecessarily increase the weight and cost, leading to energy waste.

  The present invention has been made in view of the above circumstances, and provides a power supply device for a vehicle capable of optimizing a power supply mounted on a vehicle having two voltage systems and ensuring stable power supply. It is aimed.

To achieve the above object, a power supply device for a vehicle according to the present invention includes a power supply for a first voltage system and a power supply for a second voltage system having a voltage higher than that of the first voltage system. The power source of the first voltage system is used as the power source of the control device of the vehicle, and the power source of the second voltage system is used as a power source different from the power source of the first voltage system. It is characterized in that it is a common power source for a heater heating type electric heating catalyst that is interposed in an exhaust system and energizes only when the engine is started, and a power steering device that generates a steering assist force when the vehicle is running .

The power supply device for a vehicle according to the present invention uses the power supply of the first voltage system of the two voltage systems as the power supply of the control device of the vehicle, and the power supply of the second voltage system on the high voltage side as the first power supply. as another supply of the supply voltage system, the actual use time as at engine start-up only with such during running after the engine start is shared between that electric heating catalyst and the power steering device different to physicians each other, There is no need to make the power capacity of the both powers in addition, and stable power supply can be ensured while optimizing the on-vehicle power supply.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system configuration diagram showing a power supply system of a vehicle according to an embodiment of the present invention.

  In FIG. 1, reference numerals 1 and 2 denote batteries mounted on a vehicle. In this embodiment, the battery 1 has a nominal voltage of 12V (vehicle operating voltage of 14V), and the battery 2 has a nominal voltage of 36V (12V × 3; vehicle operation). It is a battery of hour voltage 14V × 3 = 42V). Hereinafter, the battery 1 is referred to as a low voltage battery, the battery 2 is referred to as a high voltage battery, the voltage system (first voltage system) of the low voltage battery 1 is a 14V system, and the voltage system of the high voltage battery 2 (second voltage system). ) Is described as 42V system.

  In the present embodiment, the high voltage battery 2 is charged by a motor generator 4 disposed in the engine 3. The motor generator 4 is connected to a crank sprocket 5 of the engine 3 via a belt 6 and connected to a pulley 7 at the end of the rotary shaft. The motor generator 4 is rotated by the engine 3 to generate electric power and drive the engine 3 when the vehicle starts after idling is stopped. Then, restarting is performed, and it is electrically connected to the inverter device 8.

  A 42V line connected to the high voltage battery 2 is connected to a terminal on the 42V side of the inverter device 8, and a load requiring a large amount of power is connected to the 42V line. As a load that requires a large amount of power, there is a starter motor 9 that is used only at the time of the first engine start, and is connected to a 42V wiring via a relay contact (normally open contact) of the relay RY1. In addition, as an electric load that requires a large amount of power but often differs in actual use time, the heater heating type electric heating catalyst 11 interposed in the exhaust pipe 10 of the engine 3 and the driver's steering 12 are operated. On the other hand, there is a power steering device 13 that generates a steering assist force, which is connected to a 42V system wiring via each relay contact (normally open contact) of relays RY2 and RY3.

  In this embodiment, the electric heating catalyst 11 includes a catalyst 11a that purifies the exhaust gas of the engine 3 and a heater 11b that has a honeycomb-shaped passage disposed immediately upstream of the catalyst 11a. When the engine is cold, the heater 11b is energized to heat the exhaust gas passing through the heater 11b, thereby activating the catalyst 11a early. The heater 11b is a normal electric resistance heater. By using a 42V system high voltage power supply, current consumption can be reduced compared to the case of using a conventional 14 system power supply. The cost can be reduced, and the battery voltage drop can be suppressed and the influence on other in-vehicle devices can be avoided.

  Further, in this embodiment, the power steering device 13 includes an electric motor connected to the steering mechanism of the steering 12 and a drive circuit that controls the driving of the electric motor, and assist power is generated by the rotational torque of the electric motor. Is generated. By supplying 42V power to this power steering device 13, not only can the current consumption be reduced compared to the case of using a conventional 14 power supply, but also to other in-vehicle devices caused by a battery voltage drop. It is possible to obtain a larger assist force while avoiding the influence of the above.

  The electric heating catalyst 11 may be a catalyst that supports the surface of a porous conductor and uses the catalyst carrier as an electric resistance heater. Further, the power steering device 13 may generate an assist force using hydraulic pressure generated by an electric pump.

  The electric heating catalyst 11 and the power steering device 13 require electric power only during the cold start of the engine 3 while the latter normally requires electric power during vehicle travel after the engine starts. Therefore, the electric heating catalyst 11 and the power steering device 13 are often used at different times and are rarely used at the same time. Therefore, the electric heating catalyst 11 and the power steering device 13 have a high voltage of 42V. Even if the system power supply is shared, it is not necessary to estimate the power capacity obtained by adding the load capacities, and the power capacity can be optimized.

  From the above, the relay RY3 that connects the high voltage battery 2 and the power steering device 13 can be omitted.

  On the other hand, as a low-voltage 14-system voltage system, a DC-DC converter 14 that converts a 42V voltage into a 14V voltage is connected to the inverter device 8. The low-voltage battery 1 is connected to the wiring connected to the DC-DC converter 14, and low voltage loads (14V) such as various lamps and audio not shown through a relay contact (normally open contact) of the relay RY4. Load) is connected.

  The inverter device 8 and the relays RY1 to RY4 are controlled by an electronic control unit (ECU) 50. The ECU 50 is configured to include peripheral circuits such as a constant voltage circuit and an input / output circuit with a microcomputer at the center. The ECU 50 controls the engine 3, performs idle stop control for automatically stopping and restarting the vehicle, and power steering. Steering assist control via the device 13, control of the motor generator 4 via the inverter device 8, management of the charge / discharge state of the high voltage battery 2, etc.

  In FIG. 1, the ECU 50 is shown as a single unit having a plurality of control functions, but each control function may be distributed to a plurality of units and connected to each other via a communication line. .

  The ECU 50 is operated with a predetermined stabilized constant voltage by supplying a 14V power supply to an internal constant voltage circuit. To the input side of the ECU 50, an ignition switch 15, a starter switch 16, other various switches and signals from various sensors (not shown), a monitor voltage of the high voltage battery 2 (42V system), and the like are input. Further, the output side of the ECU 50 is connected to the inverter device 8, relays RY1 to 4, and other various 14V operation actuators provided in the engine 3. Further, the voltage drop while monitoring the 42V system voltage, etc. An alarm device 17 is connected to issue an alarm to the driver by lighting or sound when an abnormality is detected.

  In the vehicle power supply system configured as described above, when the ignition switch 15 is turned on during vehicle operation, the ON signal from the ignition switch 15 is detected by the ECU 50, and the ECU 50 is based on signals from various sensors. It is determined whether or not it is cold. When the ECU 50 determines that the battery is cold, the relay coil of the relay RY2 connecting the high voltage battery 2 and the heater 11b of the electric heating catalyst 11 is energized to close the relay contact, and the heater 11b is energized and the catalyst 11a is energized. Aim for early activation of.

  At this time, the ECU 50 can simultaneously operate the power steering device 13 by energizing the relay coil of the relay RY3 that connects the high voltage battery 2 and the power steering device 13 and closing the relay contact of the relay RY3. State. That is, normally, the need for steering is low until the engine is started after the ignition switch is turned on, and the electric heating catalyst 11 and the power steering device 13 consume power at the same time even when the power steering device 13 can be energized. Since there is little to do, the relays RY2 and RY3 are simultaneously turned on.

  Note that the ECU 50 monitors the voltage of the high-voltage battery 2, and the voltage of the high-voltage battery 2 is set even if the power steering device 13 is used while the electric heating catalyst 11 is energized. When it is detected that the voltage has dropped below the voltage, the relay RY3 is turned off to take action such as shutting off the power steering device 13, and the alarm device 17 is activated to issue a warning to the driver.

  Thereafter, when the starter switch 16 is turned on, the ON signal of the starter switch 16 is detected by the ECU 50, energizes the relay coil of the relay RY1, closes the relay contact, energizes the starter motor 9, and starts the engine 3. Start. Further, when the set time has elapsed after the electric heating catalyst 11 is energized, or when the catalyst temperature, the exhaust temperature, the cooling water temperature, etc. reach the set temperature, the energization to the relay RY2 is cut off and the relay contact is made. Open and energization of the electric heating catalyst 11 is terminated.

  As described above, in the present embodiment, the power source for the power steering device 13 that particularly requires driving power in the vehicle and the electric heating catalyst 11 that is particularly necessary for catalyst activation at the time of starting the engine is a high voltage. Since the high-voltage battery 2 is shared by the power steering device 13 and the electric heating catalyst 11 that are shared by the battery 2 and rarely used at the same time, the electric power required for the electric heating catalyst 11 and the power steering device 13 It is not necessary to have a power capacity that takes into account the required power at the same time, and stable power supply can be performed while optimizing the power supply.

  Furthermore, since the power source of the electric heating catalyst 11 and the power steering device 13 is a power source different from that of other in-vehicle devices such as the ECU 50, the operation of the other in-vehicle devices is not affected. Reliable and stable vehicle control and its operation can be ensured.

  In this embodiment, the engine 3 on which the motor generator 4 is mounted has been described as an example. However, an alternator is provided instead of the motor generator, and the rectifier output of the alternator is a 42V high voltage battery 2 and an electric heating catalyst 11. In addition to being supplied to the power steering device 13, the power steering device 13 may be supplied to the 14V low voltage battery 1 and each load via the DC-DC converter 14.

The system block diagram which shows the power supply system of the vehicle which concerns on one Embodiment of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Low voltage battery 2 High voltage battery 3 Engine 11 Electric heating catalyst 11a Catalyst 11b Heater 13 Power steering apparatus 50 Electronic control apparatus
Agent Patent Attorney Susumu Ito

Claims (4)

In a power supply device for a vehicle having a power supply of a first voltage system and a power supply of a second voltage system having a higher voltage than the first voltage system,
The power source of the first voltage system is used as the power source of the control device of the vehicle, and the power source of the second voltage system is used as a power source different from the power source of the first voltage system. A power supply device for a vehicle, characterized in that it is used as a common power source for a heater-heating type electric heating catalyst that is interposed between the heater and that is energized only when the engine is started and a power steering device that generates a steering assist force when the vehicle is running .   2. The power supply device for a vehicle according to claim 1, wherein the electric heating catalyst and the power steering device are connected to the second voltage system so that they can be energized simultaneously.   The power source for a vehicle according to claim 1 or 2, wherein the electric heating catalyst includes a catalyst for purifying exhaust gas of the engine and a heater disposed on the upstream side of the catalyst. apparatus.   3. The power supply device for a vehicle according to claim 1, wherein the power steering device is an electric power steering device that generates a steering assist force by an electric motor.

Images