JPS6018626Y2 - Glow plug timer for diesel cars - Google Patents

Description

[Detailed description of the invention] The present invention energizes the glow plug for a predetermined time when starting a diesel engine, and stops energizing the glow plug if the voltage applied to the glow plug exceeds a predetermined value after the diesel engine has started. The present invention relates to a glow plug timer for a diesel vehicle that is designed to automatically shut off, thereby facilitating the starting of a diesel engine and preventing disconnection of the glow plug due to overvoltage application.

Typically, a diesel engine is preheated by a glow plug and then started by a starter motor.

Here, the driver determines whether or not the engine can be started based on the glowing state of the glow pilot.

Therefore, errors in judgment occur depending on the surrounding brightness and individual differences, and there are also serious drawbacks.

Therefore, it is conceivable to use a timer to keep the power supply time to the glow plug constant.

However, it is not necessarily practical to maintain a constant energization time to the glow plug even when environmental conditions change, such as in summer, winter, in tropical regions, or in cold regions.

For this reason, it is conceivable to make the time for energizing the glow plug variable in accordance with the water temperature of the radiator that cools the engine.

However, if the power to the glow plug is cut off from the time the starter motor is started, there is a risk that the engine will stop immediately even if it is temporarily started.

Therefore, it is conceivable to continue supplying electricity to the glove lug for a certain period of time even after the engine has started.

However, when the engine starts and the generator outputs electric power, and the voltage applied to the glow plug increases, the glow plug becomes more likely to break.

This invention was devised in view of the above-mentioned problems.The glow plug used to preheat the engine continues to be energized for a certain period of time even after the engine has started, and the generator operates to reduce the voltage applied to the glow plug. If the glow plug rises, the power to the glow plug is immediately cut off.

Hereinafter, preferred embodiments of the glow plug timer for diesel vehicles according to the present invention will be described in detail based on the drawings.

Reference numeral 1 designates a part of the timer, which is composed of a delay circuit 21, a comparison circuit 3, and a first relay 4.

The delay circuit 2 includes a capacitor 20 whose one end is grounded, a resistor 21 connected to the other end of the capacitor 20, and a resistor 21.
The diode 22 is connected in parallel to the diode 22.

The anode side of the diode 22 is connected to the other side of the capacitor 20.

The other end of the resistor 21 is connected to a fixed contact 61 of the key switch 6.

Here, if the resistor 21 is configured with a variable resistor, the delay circuit 2
The activation time limit can be set freely.

Furthermore, if the resistor 21 is replaced by a thermistor that detects the water temperature of the radiator that cools the engine, the operating time period can be changed in accordance with the radiator water temperature.

The key switch 6 is composed of fixed contacts 60, 61, 62 and a movable contact piece 63, and the movable contact piece 63 is grounded via a DC power source 7.

The comparison circuit 3 includes resistors 30 and 31 and a comparator 32.

The resistors 30 and 31 are connected in series and arranged between the fixed contact 61 of the key switch 6 and the ground, and constitute a voltage dividing circuit, the voltage dividing point A of which is connected to the non-inverting input part of the comparator 32. are doing.

A non-inverting input portion of the comparator 32 is connected to the connection point B of the delay circuit 2, that is, to the other side of the capacitor 20.

The output section of the comparator 32 is grounded via the relay coil 40 of the first relay 4.

In the first relay 4, the relay switch 41 is turned on by excitation of the relay coil 40.

One side of the relay switch 41 is grounded via the DC power supply 7, and the other side of the relay switch 41 is grounded via the glow pilot 80 and glow plug 81.

9 is a second relay, which includes a relay coil 90 and a relay switch 91 that is turned on when the relay coil 90 is excited.
It consists of

Relay coil 90 is arranged between fixed contact 62 of key switch 6 and ground.

One side of the relay switch 91 is grounded via the DC power supply 7, and the other side of the relay switch 91 is grounded via the glow plug 81.

Therefore, when the relay switch 41 is turned on, the glow pilot 80 and the glow plug 81 are energized at the same time.

When the relay switch 91 is turned on, only the glow plug 81 is energized.

Reference numeral 5 denotes a voltage detection section, which includes diodes 50 and 51, a Zener diode 52, resistors 53, 54, and 55, and a comparator 56.

The anode of the diode 50 is connected to the connection point between the glow plug 81 and the glow pilot 80, and the cathode of the diode 50 is grounded via resistors 53 and 54.

A voltage dividing circuit is constituted by the resistors 53 and 54, and the voltage dividing point C is connected to the non-inverting input part of the comparator 56, and the output part of the comparator 56 is connected to the connection point of the delay circuit 2 via the diode 51. Connected to B.

The anode of the Zener diode 52 is grounded,
The cathode of the Zener diode 52 is connected together with one of the resistors 55 to the inverting input of the comparator 56.

The other end of the resistor 55 is connected to a fixed contact 61 of the key switch 6.

The voltage detection unit 5 detects when the voltage applied to the glow plug 81 exceeds a predetermined value, and detects the voltage applied to the glow plug 81.
It has the effect of rapidly charging the battery.

In the key switch 6, the fixed contact 60 is in the OFF position, the fixed contact 61 is in the preheating position, and the fixed contact 62 is in the start position.

Since the glow plug timer for diesel vehicles according to the present invention has the above-described structure, it operates as follows.

First, when the movable contact piece 63 of the key switch 6 is in contact with the fixed contact 60, that is, when the key switch 6 is in the OFF position, power is supplied to the timer part 1 and the voltage detection part 5 from the DC power supply 7. It does not work because it is not installed.

Therefore, the first relay 4 and the second relay 9 do not operate, and the glow pilot 80 and glow plug 81 also remain inoperative.

The capacitor 20 is then in an uncharged state.

Next, move the key switch 6 to the preheat position, that is, the key switch 6
When the movable contact piece 63 is brought into contact with the fixed contact 61, the timer part 1 and the voltage detection part 5 are energized, and the capacitor 20 starts charging via the resistor 21.

Here, until the capacitor 20 exceeds a predetermined voltage value, the potential at the connection point B of the delay circuit 2 is lower than the potential at the voltage dividing point A, so the comparator 32 derives an H level output, and the relay coil 40 energized, relay switch 4
1 turns on.

Then, the glow pilot 80 and glow plug 81 are energized to start preheating the engine.

When a predetermined period of time has elapsed and the potential at the connection point B of the delay circuit 2 exceeds the potential at the voltage dividing point A, the comparator 32 outputs an L level output.

Therefore, the relay coil 40 is demagnetized, and the relay switch 4
1 is OFF.

At this time, when the key switch 6 is switched to the start position, the relay coil 90 is energized, the relay switch 91 is turned on, the glow plug 81 continues to be energized, and the starter motor (not shown) is operated to start the engine.

Further, at this time, the charge stored in the capacitor 20 is discharged via the diode 22, resistor 31, 30, etc.

When the key switch 6 is returned to the preheating position, the relay coil 90 is demagnetized and the relay switch g1 is turned off.

At this time, the capacitor 20 starts charging, and the comparator 32 outputs an H level output for a predetermined period of time, and continues to energize the glow plug 81 via the relay 4 of the waistband 1.

Even after the engine has started, the glow plug 81
The purpose of energizing the engine for a predetermined period of time is to ensure that the engine starts completely so that it does not stop midway.

Note that once the engine has started and a predetermined time has elapsed, the potential at the connection point B of the delay circuit 2 exceeds the potential at the voltage dividing point A, so the comparator circuit 3 stops the operation of the first relay 4, and the glow plug 81 Automatically cuts off power to.

By the way, when the engine starts, the generator is activated and the glow plug 81 continues to be energized by the operation of the timer part 1.

Here, if the output voltage of the generator (not shown) increases abnormally, the glow plug 81 is likely to be disconnected due to the application of overvoltage.

However, since the present invention includes the voltage detection section 5, this problem can be solved.

Next, the operation of the voltage detection section 5 will be explained.

When the key switch 6 is switched to the preheating position and the glow plug 81 is energized, the potential at the connection point C of the resistors 53 and 54 is set to be lower than the potential on the cathode side of the Zener diode 52.

Therefore, the output side of the comparator 56 is an L channel, and the voltage detection section 5 does not affect the operation of the delay circuit 2 at all.

However, the output voltage of all generators increases, and glow plug 8
When the voltage applied to the resistors 53 and 54 increases, the potential at the connection point C of the resistors 53 and 54 increases.

Then, when the potential at the connection point C becomes higher than the cathode potential of the Zener diode 52, the comparator 56 outputs an H level output, which is connected to the capacitor 20 via the diode 51.
charge quickly.

As a result, the potential at the connection point B of the delay circuit 2 exceeds the potential at the voltage dividing point A, and the comparator 32 stops the operation of the first relay 4, thereby cutting off the current supply to the glow plug 81. 81 from being disconnected due to overvoltage application.

Since the glow plug timer for diesel vehicles according to the present invention has the above-described structure and operation, it has the following excellent effects.

In other words, it is equipped with a voltage detection section that detects the voltage applied to the glow plug, rapidly charges the time setting capacitor in the timer, and stops the timer operation, so when the engine starts, the output voltage of the generator increases. However, if the voltage applied to the glow plug exceeds a predetermined value, the power to the glow plug can be immediately cut off via a portion of the timer.

Therefore, it is possible to prevent the glow plug from breaking due to overvoltage application.

In addition, since the output of the voltage detection section is connected to the capacitor of a part of the timer, it is possible to prevent the timer from erroneously stopping due to noise, and from erroneously restarting the timer after power is cut off to the glow plug. Since it is connected to the terminal of the glow plug, various effects such as being able to appropriately detect the voltage applied to the glow plug can be achieved.

[Brief explanation of the drawing]

The drawing is an electrical circuit diagram showing a preferred embodiment of the glow plug timer for diesel vehicles according to the present invention. 1... Part of the timer, 2... Delay circuit,
3...Comparison circuit, 4...First relay 5...Voltage detection unit, 6...Key switch, 9...First relay 2 relay, 20...
Capacitor, 21... Resistor, 32, 56...
... Comparator, 80 ... Glow pilot, 81 ... Glow plug.

Claims (1)

[Scope of utility model registration request] When the key switch is switched to the preheating position, the output is turned on to energize the glow plug, and after a predetermined period of time, the output is cut off, and the voltage applied to the glow plug exceeds a predetermined value. A glow plug timer for a diesel vehicle, characterized in that the glow plug timer for a diesel vehicle is equipped with a voltage detection section interposed between the glow plug and a capacitor of a part of the timer to detect this and stop the timer.