JPH0660617B2 - Starting motor protection device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a starting device for an internal combustion engine using a permanent magnet field type DC electric motor, and more particularly to a protection device against excessive rotation of the electric motor in such a device.

[Background of the Invention]

As is well known, internal combustion engines such as gasoline engines require a starter, a so-called starter.Therefore, in general, a starter motor composed of a DC motor is provided, and the starter motor is a system in which the engine is rotated only at the time of starting. Has been adopted.

In such a starter, in order to enable the engine to be started by a relatively small motor, the motor and the engine are connected via a rotation transmission mechanism having a considerably large reduction ratio. Therefore, when the engine starts to start completely and the engine starts to generate torque by itself, even if the engine is at idle speed, the starter motor will rotate at an excessive speed, which may cause damage. Cause

Therefore, in general, a magnet switch is provided so that the gear meshes only when the ignition switch (also called a key switch) is operated to the start position at the time of starting, and an overrunning clutch is provided so that the starter motor does not overrotate. I am trying.

However, if the operation of the magnet switch mechanism or the overrunning clutch is abnormal, and the rotation transmission state is maintained between the starter motor and the engine even after the complete explosion of the engine, the starter motor is destroyed in a short time.

Therefore, a device in which a centrifugal switch is provided on the starter motor to detect that the starter motor is over-rotating and protect the starter motor is disclosed in, for example, Japanese Patent Laid-Open No. 49-95045.
It is proposed by the official gazette.

However, such a conventional device has a drawback that an extra device such as a centrifugal switch for detecting an excessive rotation of the starter motor is required, and the cost is likely to increase.

[Object of the Invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to detect abnormal over-rotation of a starter motor easily and with almost no additional device, and to reliably protect the starter motor at low cost. The present invention provides a protection device for a starter motor.

[Outline of Invention]

To achieve this object, the present invention uses a permanent magnet field type DC electric motor as a starter motor, detects the terminal voltage of this DC electric motor when the ignition switch is in the ignition position, and reaches a predetermined value or more. When it does, it is judged that it is in an abnormal overspeed state and an alarm is issued.

Example of Invention

Hereinafter, embodiments of the starting motor protection device according to the present invention will be described in detail with reference to the illustrated embodiments.

The figure is an embodiment of the present invention, in which 1 is a power supply battery, 2 is an ignition switch, 3 is a starter, 4 is a voltage comparison circuit, 5 is a logic circuit, 6 and 7 are diodes, 8 is a transistor, 9 is an alarm device.

The power supply battery 1 is, for example, a 12 [V] on-vehicle battery, and is used as a power supply for various electric vehicle components other than the starter drive.

The ignition switch 2 is also called a key switch, and it is operated by a dedicated key to turn off the ignition and IG.
It is well known that the engine ignition system is powered in the IG position and the starter is powered in the S position.

The starter 3 is a DC motor 3 having a permanent magnet field 31.
0, a magnet switch 32, and a magnet switch contact 33, which are also well known.

Voltage comparator circuit 4 comprises a comparator 40, the positive input to the positive terminal of the DC motor 30 and respectively connected to the negative input to the positive terminal of the battery 1, towards the terminal voltage V _M of the DC motor 30 is a battery, It serves to generate an output A that goes high only when it goes above a voltage V _{B of} 1.

The logic circuit 5 is composed of an inverter 50 and an AND gate 51, and one of its input terminals has a terminal voltage V of the DC motor 30.
_M , and the magnet switch 32 at the other input end
Voltage _{V C} is supplied to the terminal, the voltage V with respect to the voltage _{V M
It} serves to generate an output B that goes high when _C goes below a predetermined value.

The diodes 6 and 7 perform an OR operation with respect to the inputs of the signals A and B, and serve to bring the base of the transistor 8 to the high level when either of the signals A and B goes to the high level.

The transistor 8 conducts when the ignition switch 2 is operated to the IG position and the base becomes a high level while in that state, and operates a warning device 9 including a buzzer, a display lamp and the like.

Next, the operation of this embodiment will be described.

First, when the engine is started, the ignition switch 2 is operated to move it from the OFF position to the IG position, and then to the S position, a current flows from the battery 1 to the magnet switch 32, and a gear engagement (not shown) is performed. When the mechanism operates, and then the contact 33 is closed, the DC motor 30 generates the original torque and rotationally drives the engine.

Then, after entering this state, if the engine is started (complete explosion), the ignition switch 2 is returned from the S position to the IG position, the circuit for the magnet switch 32 is turned off, the contact 33 is opened, and the electric motor 30 is opened.
Also stop.

The above operation is the same as that of the conventional starter.

Next, the operation of the voltage comparison circuit 4 and the logic circuit 5 during the operation of the starter will be described.

First, looking at the voltage comparison circuit 4, the voltage comparator 40
The voltage V _{B of the} battery 1 supplied to one input is maintained at a substantially constant voltage, for example, 12 [V]. on the other hand,
Looking at the voltage V _M which is the + input, this voltage V _M
M becomes almost equal to the voltage V _B when the ignition switch 2 is operated to the S position and the contact 33 is closed.
When the contact 33 is open, V _B > V _M. Furthermore the ignition switch 2 is returned to the IG position, after the motor 30 is stopped and the voltage V _M becomes zero, of course, the state of V _B> V _M does not change.

Therefore, as long as the starter 3 operates normally, the output A of the voltage comparison circuit 4 is kept at the low level and the alarm device 9 does not operate.

However, even if some abnormality occurs and the engine is started, the ignition switch 2 is returned to the IG position and the contact 33 is opened, but the power transmission between the electric motor 30 and the engine is not separated. , The electric motor 30 is reversely driven by the engine and becomes in the over-rotation state.

Then, since this electric motor 30 is of a so-called permanent magnet field type including the permanent magnet field 31, it immediately operates as a generator when a negative torque state is reached, and its rotation speed exceeds the rated value. Then, the terminal voltage V _M becomes higher than the voltage V _{B of the} battery 1, and V _B <V _M.

Therefore, in this state, the output A of the voltage comparison circuit 4 becomes high level, and this is given to the base of the transistor 8 via the diode 6, so that the transistor 8
Is turned on, and the alarm device 9 operates to give an alarm.

Therefore, if a person operating the ignition switch 2, such as a driver of a car, returns the ignition switch 2 to the OFF position in response to the operation of the alarm device 9, the engine is stopped and the electric motor 30 is in an abnormal overspeed state. It is possible to prevent the destruction.

Next, regarding the logic circuit 5, this circuit 5 outputs the output B when the contact 33 is not opened even though the ignition switch 2 is returned from the S position to the IG position due to some abnormality such as welding. It is for setting the high level and for issuing an alarm. And gate 51
Since the lower side of the input of which the voltage V _C applied through inverter 50, since the ignition switch 2 is voltage V _C is equal to the battery voltage V _B as long as the S position, the output B is at a high level It cannot be. On the other hand, contact 33
Is closed and the ignition switch 2 is not in the S position, both inputs of the AND gate 51 become high level, and only then the output B becomes high level.

Therefore, according to the present embodiment, even if the starter motor does not have a special over-rotation detecting means such as a centrifugal switch and is simply added to a simple electronic circuit, even if the electric motor is abnormally over-rotated due to an overrun phenomenon. , Or even if the contact of the magnet switch is welded by the arc,
Since it is possible to accurately alert the driver of the abnormal state, it is possible to prevent damage to the starter motor.

〔The invention's effect〕

According to the present invention, when the electric motor is abnormally over-rotated,
Alternatively, a simple protective device for the starting motor that can give an appropriate alarm even when the contact of the magnet switch has not returned to the off state and can prevent damage to the motor in advance. It can be provided in a circuit configuration.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a starting motor protection device according to the present invention. 1 ... Battery for power supply, 2 ... Ignition switch, 3 ... Starter, 4 ... Voltage comparison circuit, 5 ... Logic circuit, 6,7 ... Diode, 8 ... Transistor, 9
…… Alarm, 30 …… Permanent magnet field type DC motor, 31
...... Permanent magnet field, 32 …… Magnet switch, 33
...... Contact, 40 ...... Voltage comparator, 50 …… Inverter,
51 …… And gate.

Claims (1)

[Claims] 1. A starter motor protection device for issuing an alarm in response to a voltage generated when a permanent magnet field type starter motor overruns, wherein the protection device protects the motor from a battery terminal voltage (V _B ). A voltage comparison circuit that outputs when the terminal voltage (V _M ) becomes high, and an output when the terminal voltage (V _M ) of the motor becomes higher than the terminal voltage (V _C ) on the power supply side of the solenoid coil of the magnet switch. And a switching transistor that activates an alarm when an output from either the voltage comparison circuit or the logic circuit is output.