JPS6115257Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a mismatch protection device for a starter motor.

Regarding conventional devices of this type, starting motor protection devices have been devised that issue an alarm in response to the power supply voltage when the starting motor overruns, but the protective action after overrun detection is artificial. Therefore, a typical driver may make a mistake in judgment, and the protection function may not function sufficiently.

This invention was made to improve the above-mentioned drawbacks, and it has the excellent functions described below to protect the starter motor from overrun (overspeed) conditions, and also prevents the ring gear of the engine and the pinion of the starter motor from collapsing. It is an object of the present invention to provide a starting motor protection device that can instantly protect the device even when the end surfaces of the gears rub against each other when the device is started in a meshed state, that is, a so-called gear sluggish phenomenon occurs. An embodiment of this invention shown in FIG. 1 will be described below.

In the figure, 1 is a battery attached to an engine (not shown), 2 is a key switch, 3 is a starter motor,
3a is a connecting terminal for the main contact 4a of the magnetic switch 4 attached to the starting motor 3, 3b is a connecting terminal for energizing the coils 4b and 4c of the magnetic switch 4, and 3c is for connecting the input voltage of the DC motor 5. Terminal 6 for detection is a semiconductor switching element inserted in series between the key switch 2 and the connection terminal 3b, and includes a bipolar transistor,
Power devices such as SCR and V-FET are used and are switched by a control device 7 described below. 8 and 9 are resistors which receive the voltage at the terminal 3c, divide the voltage to about a fraction, and then input it to the voltage follower 10 for impedance conversion to facilitate subsequent signal processing. Reference numeral 11 is a comparator, and 12 and 13 are resistors that hold a voltage corresponding to the output voltage of the battery 1 immediately before the starting motor 3 operates, and divide the voltage supplied to the terminal Vcc in the figure to obtain the set voltage (in the figure). (voltage at point B) is input to the comparator 11 and compared with the output voltage of the voltage follower 10 (voltage at point C in the figure) to generate an output. 14 is a gate circuit of the comparator 11, which receives a line voltage drop pulse due to an inrush current generated when the DC motor 5 operates, and connects the capacitor 1.
5 cuts the DC component, extracts only the pulse signal, triggers the monostable multivibrator 16, and outputs a rectangular wave with a predetermined pulse width (time width). 17 is an inverter, and 18 is a NAND gate, which makes the output of the comparator 11 conductive after a predetermined period of time. With the above circuit configuration, when there is no signal from the comparator 11, no signal is sent out even if the gate function is opened.The output of the NAND gate 18 is connected to the switching element 6 to switch the element 6. Reference numeral 19 denotes a self-holding circuit which holds the NAND gate signal and shuts off the switching element.

The operation of the embodiment configured as described above will be explained using the graph of FIG. 2. When the key switch 2 is closed, the control device 7 makes the switching element 6 conductive and energizes the magnetic switch 4. , the main contact 4a is closed and the main current is applied to the DC motor 5. The voltage waveform at point A at this time is
To explain with a diagram, the above bias causes the pinion (not shown) to connect to the ring gear (not shown) of the engine.
When normal engagement is achieved, a cranking voltage shown by curve D is generated. This voltage drop is mainly caused by the internal resistance of the battery 1, and a certain amount is also added by the DC resistance of the connecting cable. At this time, if a phenomenon occurs in which the pinion and ring gear do not mesh normally and rotate while touching each other at their end faces (gear locking phenomenon), the potential at point A exhibits no-load voltage characteristics as shown by the broken line E, and the monostable multi-function Vibrator 16 setting time Tmsec
After (several tens to hundreds of milliseconds), the voltage at point C becomes higher than the set voltage at point B, and the NAND gate 18 is inverted and the semiconductor switching element 6 is cut off. In the above state, the self-holding circuit 19 prevents the magnetic switch 4 from being energized even if the key switch 2 continues to be closed.
operates, so even if the DC motor is deenergized and the voltage at point A drops again after the protection circuit is activated, the starter motor will not be reenergized. Note that when the engine starts and enters an overrun state, the DC motor 5 becomes equivalent to no-load rotation, and the potential at point A exceeds the potential when the gear is changed. Therefore, the voltage at point C becomes higher than the voltage at point B, and at this time, the set time by monostable multivibrator 16
If Tmsec has elapsed, the NAND gate 18 immediately generates an output L to cut off the switching element 6, and the DC motor 5 is de-energized.

In addition, although the above example is applied to an electromagnetic push type starting motor, it is of course applicable to other pinion engagement type starting motors such as inertial sliding type (Bendix type) and auxiliary rotation type. It is. Further, although the no-load rotation state is determined based on the input voltage of the DC motor, the same effect can be achieved even if the determination is performed using the input current.

As described above, this invention prevents the occurrence of gear change due to misalignment of the starter motor, etc., by configuring a protection circuit to detect the power input terminal voltage in a no-load state and release the energization of the starter motor. Alternatively, when an overrun phenomenon occurs, the energization of the starter motor can be stopped instantaneously and reliably, thereby improving the reliability of the starter motor and providing a low-cost protection device.

[Brief explanation of the drawing]

FIG. 1 is a connection diagram showing an embodiment of this invention, and FIG. 2 is an explanatory diagram of the operation of the protection device of FIG. 1. In the figure, 1 is a battery, 2 is a key switch, 3 is a starting motor, 4 is a magnetic switch, 5 is a DC motor, 6 is a semiconductor switching element, 10 is a voltage follower, 11 is a comparator, 16 is a monostable multivibrator, 18 is a NAND gate, and 19 is a self-holding circuit. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Scope of utility model registration request] a starter motor having a DC motor connected to the battery via a magnetic switch and supplied with operating current; a key switch and switching element for energizing the magnetic switch; and an input terminal of the DC motor. A comparator that compares the voltage corresponding to the voltage with a set voltage corresponding to the battery no-load voltage and generates an output when the voltage becomes higher than the set voltage, and a comparator that is triggered when the DC motor starts and outputs the output of the comparator. and a gate circuit that activates after a predetermined time, the switching element being controlled by the output of the gate circuit to release the energization of the magnetic switch. Protective device.