JP3506035B2 - Engine starter - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine starting device, and more particularly to an engine starting device for driving a starter motor using a battery and a large-capacity capacitor. 2. Description of the Related Art Generally, an engine is started by driving a starter motor with a battery. At this time, a large current flows instantaneously from the battery. Since the battery involves a chemical change in charging and discharging, there is a limit to continuous durability, and frequent starting of the engine shortens the life of the battery. In order to prevent this, a technique of driving a starter motor using a large-capacity capacitor has been proposed. This is because a large-capacity capacitor is suitable for instantaneous energy supply, because the stored energy is small but the internal resistance is small compared to the battery.
In addition, repeated charging / discharging does not involve a chemical change unlike a battery, so that characteristic deterioration is small. [0003] When the engine temperature is low, the viscosity of the engine increases, the friction increases, and a long start is required. In such a case, the engine cannot be started by driving the starter motor with only the large-capacity capacitor. Therefore, current is supplied from the battery to the starter motor in addition to the large-capacity capacitor. JP-A-7-3056
The engine starting device disclosed in Japanese Patent Publication No. 72-72, since the discharge amount decreases when the temperature of the large-capacity capacitor is low, detects the capacitor temperature and uses both the battery and the large-capacity capacitor even when the detected temperature is low. To drive the starter motor. [0004] However, the technology disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-305672 discloses an engine using a battery and a large capacity capacitor in combination when the temperature of the engine or the large capacity capacitor is low. Since starting is performed, there is a problem that the life of the battery is shortened under conditions where the engine is frequently started. Therefore, the present invention solves the above-mentioned problem, and even when the temperature of the engine or the large-capacity capacitor is low,
It is an object of the present invention to provide an engine starting device that starts an engine with a large-capacity capacitor as much as possible and uses a battery in an auxiliary manner. FIG. 1 is a diagram showing the basic configuration of the present invention. An engine starter according to the present invention that achieves the above object provides an engine starter that supplies power from at least one of a battery 1 and a capacitor 2 to a starter motor 3 at the time of engine start. 1 and a voltage detecting means 5 for detecting the voltages of the battery 1 and the capacitor 2 and a voltage detecting means 5 provided between the capacitor 2 and the starter motor 3 for providing a voltage between the capacitor 1 and the starter motor 3. A first opening / closing means 6 for energizing or shutting off, a second opening / closing means 7 provided between the battery 1 and the capacitor 2 for energizing or shutting off between them, and closing the first opening / closing means 6 when starting the engine; It is assumed that the battery voltage detected by the voltage detecting means 5 is higher than the capacitor voltage detected by the voltage detecting means 5. , A control unit 8 for controlling to close the second opening and closing means 7, comprising a control unit 8,
The voltage is detected by the voltage detecting means 5 for a predetermined period after the start of the engine start.
The output battery voltage is detected by the voltage detecting means 5.
When the voltage is higher than the set capacitor voltage, the second opening / closing means 7 is closed.
The control is characterized in that the control of the twisting is prohibited . With the above configuration, a capacitor voltage higher than the battery voltage is applied to the starter motor at the time of starting the engine, and the engine can be rotated at a high rotation speed, thereby improving the startability of the engine . Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 2 is a configuration diagram of an engine starting device according to one embodiment of the present invention. 1, an engine 10 is started by a starter motor 3 via a ring gear (not shown), and a generator 11
0 rotational energy is converted into electric energy. Generator 1
An alternator 13 composed of a rectifier circuit 1 and a rectifier circuit 12 converts an alternating current into a direct current and charges the battery 1 while the engine 10 is operating. The capacitor 2 has a large capacity of the electric double layer, for example, a capacitance of about 100F. An electronic control unit (ECU) 8 comprises a well-known microprocessor, not shown, a CPU for performing arithmetic processing, a ROM as a memory, a RAM, a backup RAM, a clock, and an A / A for converting an analog signal into a digital signal. It comprises a D converter, a D / A converter for converting a digital signal into an analog signal, an input / output interface, and the like, and these are interconnected by a bus line. The ECU 8 is provided between the battery 1 and the capacitor 2 and has a voltage of the battery 1, for example, 12V.
A DC / DC converter 4 as a boosting means for boosting the voltage to 20 V and applying the boosted voltage to the capacitor 2 and a voltage detection circuit 5 for detecting each voltage of the battery 1 and the capacitor 2 are provided. The DC / DC converter 4 will be described later. The voltage detection circuit 5 detects the voltage of the battery 1 and the capacitor 2 by an attenuator (not shown), for example, up to 10
The pressure is reduced to volts, the maximum 10 volt analog signal is converted to a digital signal via an A / D converter, and the CPU reads this signal periodically. The ECU 8 is provided between the capacitor 2 and the starter motor 3 when the engine is started, that is, when an ignition switch (not shown) which is switched to three positions of OFF, ON and START is switched to a start position. Then, the first switch 6 for energizing or shutting off between them is closed, and the electric energy charged in the capacitor 2 is discharged to the starter motor 3. At this time, battery 1
The second switch 7, which is provided between the capacitor 2 and the current supply or cuts off between them, is controlled as follows. That is, the ECU 8 compares the voltage VB of the battery 1 detected by the voltage detection circuit 5 with the voltage VC of the capacitor 2, and when it is determined that VB ≦ VC, the starter motor is controlled only by the capacitor 2 with the second switch 7 opened. Then, when it is determined that VB> VC, the second switch 7 is closed and the starter motor 3 is driven using the battery 1 and the capacitor 2 together. As described above, when the inrush current to the starter motor at the time of starting the engine is large, the starter motor is driven only by the capacitor, and when the cranking is relatively continuous, the battery and the capacitor are used together. Drive the starter motor. FIG. 3 is a time chart showing changes in voltage of the battery and the capacitor at the time of engine start. In FIG. 3, the horizontal axis represents time (seconds), and the vertical axis represents voltage (volts). FIG. 3 shows an example in which a battery voltage of 12 volts is boosted to a capacitor voltage of 15 volts. However,
During the cold start, the viscosity of the engine increases, the friction increases, and the drive time of the starter motor increases. Therefore, the higher the pressure of the condenser is, for example, about 20 volts is better. FIG. 3 shows a state in which the ignition switch is set to the starter position at time t0 and the engine is started, and the time when the ignition switch is turned on at time t10 and the engine start is completed. Changes. Here, starting the engine means driving the starter motor. FIG. 4 is an enlarged view near time t0 in the time chart of FIG. For about 0.1 second after starting the engine with the ignition switch in the starter position at time t0, the capacitor voltage Vc fluctuates due to the rush current from the capacitor to the starter motor, and instantaneously changes from the battery voltage VB. May be lower. Therefore, even if Vc <VB for 0.1 second from t0 to t1, it is prohibited to close the second switch 7 of FIG. After time t1, when the voltage Vc of the capacitor stabilizes, and at time t2 Vc <VB, the second switch 7 is closed. FIG. 5 shows the DC / DC converter 4 shown in FIG.
FIG. It comprises a transformer 51, a field effect transistor (FET) 52 and a rectifier 53. During the operation after the engine is started, a pulse signal is input from the ECU 8 to the DC / DC converter 4 at a predetermined cycle. This pulse signal is released when the voltage of the capacitor 2 detected by the voltage detection circuit 5 exceeds 20 volts so that the capacitor 2 is charged to, for example, 20 volts. The FET 52 is turned on by the input of the pulse signal, and the transformer 5 is turned on.
For example, a voltage of 12 volts of the battery 1 is boosted to a voltage of 20 volts of the capacitor 2 according to a step-up ratio determined by a turn ratio of the primary side coil and the secondary side coil. Rectifier 5
Reference numeral 3 is provided to prevent reverse flow from the capacitor 2 to the secondary coil of the transformer 51. As described above, according to the engine starting apparatus of the present invention, the capacitor voltage is boosted to a voltage higher than the battery voltage, and the capacitor voltage becomes equal to the battery voltage when the engine is started. Until the starter motor is driven only by the capacitor, and when the capacitor voltage becomes lower than the battery voltage, the starter motor is driven by using both the battery and the capacitor. Frequent use of the battery at start-up saves battery life.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a basic configuration diagram of the present invention. FIG. 2 is a configuration diagram of an engine starting device according to an embodiment of the present invention. FIG. 3 is a time chart showing a change in voltage between a battery and a capacitor when the engine is started. FIG. 4 is an enlarged view near time t0 in the time chart of FIG. 3; FIG. 5 is a detailed view of the DC / DC converter 4 shown in FIG. DESCRIPTION OF SYMBOLS 1 ... Battery 2 ... Capacitor 3 ... Starter motor 4 ... Booster means (DC / DC converter) 5 ... Voltage detector 6 ... First opening / closing means 7 ... Second opening / closing means 8 ... Control means (ECU) 10 ... Engine 13 ... Alternator

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F02N 11/08

Claims (1)

(57) An engine starting device for supplying power to a starter motor from at least one of a battery and a capacitor at the time of starting the engine, wherein the battery is provided between the battery and the capacitor. Voltage boosting means for boosting a voltage and applying the voltage to the capacitor; voltage detecting means for detecting voltages of the battery and the capacitor; provided between the capacitor and the starter motor; A first opening / closing means, a second opening / closing means provided between the battery and the capacitor for energizing or shutting off between the first opening / closing means, and a control means for closing the first opening / closing means when the engine is started; Is greater than the capacitor voltage detected by the voltage detecting means. And control means for controlling so as to close the second opening and closing means, the control means for a predetermined period of engine start up, the electric
The battery voltage detected by the pressure detecting means is equal to the voltage
If the voltage is higher than the capacitor voltage detected by the detection means
An engine starting device for prohibiting control of closing the second opening / closing means .