JPS6235905Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a glow plug timer for diesel vehicles.

Conventionally, in diesel vehicles, drivers have judged whether or not the engine can be started by visually observing the glow plug pilot, which is activated when the glow plug is activated. Therefore, there are individual differences in this judgment, which may cause the engine to start less smoothly or cause unnecessary power consumption. Furthermore, there is a drawback that the switch for operating the glow plug may be forgotten to be turned off or turned on again.

Therefore, in order to eliminate these drawbacks, the outside air temperature or radiator water temperature, etc., were detected using several sensors with different operating points, and the glow plug was energized for a predetermined period of time depending on which sensor was activated. Although a device has been developed, it has drawbacks such as the timer's operating time being inappropriate and the cost being high due to the use of two or three sensors.
Furthermore, since the glow plug's operation is controlled by a timer, there is a risk that the glow plug may be unnecessarily energized even after the engine has started. By the way, the startability of a diesel engine generally worsens when the outside temperature or the temperature of the engine itself is low.
The related radiator water temperature is detected, and as the temperature gets lower, the engine preheating time using the glow plug is increased. However, the startability of the diesel engine has a characteristic that when the outside air temperature or the temperature of the engine itself falls below a predetermined temperature, the startability of the diesel engine hardly changes even if the engine is preheated for a longer time than a predetermined time. Conventionally, this characteristic was ignored, so there was a risk of wasting power by preheating for a longer time than necessary.

The pilot lamp was also used to check whether the engine was being preheated by the glow plug, which lights up when the ignition switch is turned on and turns off when the engine preheating time is over. However, at high temperatures, there is little time for the engine to warm up, so the pilot lamp only lights up momentarily when the ignition switch is turned on.
There is a drawback in that it is difficult for the driver to determine whether the lighting is due to the end of the engine preheating time or an abnormality in the device.

This invention was devised in order to eliminate the above-mentioned drawbacks.The water temperature of the radiator is detected by a single thermistor, and accordingly, the glow plug is energized for a certain period of time, and as soon as the engine starts, the glow plug is energized. It is configured to cut off electricity. In addition, by setting the upper and lower limits of the engine preheating time, it will not preheat for an unnecessarily long time at low temperatures, and it will preheat for a predetermined amount of time after the ignition switch is turned on at high temperatures, thereby saving power. To provide a glow plug timer for a diesel vehicle that achieves this and prevents a driver from misrecognizing it.

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

1 is a preamplifier, and an operational amplifier 10 and resistors 11 to 17 constitute a DC amplifier. In the preamplifier 1, a resistor 12 is connected between the inverting input section and the output section of the operational amplifier 10, and the inverting input is grounded via resistors 11 and 17.

The connection point between the resistors 11 and 17 is connected to the output section of the constant voltage circuit 2 via a thermistor 18 connected between terminals a and b.

Resistors 13 and 14 and resistors 15 and 16 are connected in series between terminal a and the ground.
The connection point between resistors 3 and 14 is connected to the non-inverting input section of operational amplifier 10, and the connection point between resistors 15 and 16 is connected to the output section of operational amplifier 10.

Therefore, when the thermistor 18 detects that the radiator water temperature is extremely low, for example, below -20°C, that is, when the inverting input voltage of the operational amplifier 10 is extremely low, the preamplifier 1 closes the resistor 1.
6 and a resistance element (not shown) inside the operational amplifier 10 sets the upper limit value of the output voltage. Furthermore, when the thermistor 18 of the preamplifier 1 detects that the radiator water temperature is extremely high, for example, +30°C or more,
That is, when the inverted input voltage of the operational amplifier 10 is extremely high, the lower limit value of the output voltage is set by the voltage divider circuit consisting of the resistor 15 and a resistance element (not shown) inside the operational amplifier 10. Therefore, within the above upper and lower limits, the output voltage of the preamplifier 1 decreases as the radiator water temperature rises, and the time limit of the timer circuit 3, which will be described later, is set.

3 is a timer circuit, and includes a capacitor 30 and a diode 31 connected in parallel, one of which is grounded, and a resistor 32, one of which is connected to the other of the capacitor 30 and the other to terminal a; a comparator 34 having an inverting input connected to the output of the integrating circuit and a non-inverting input connected to the output of the preamplifier 1 via a resistor 33;
It is made up of. The diode 31 has its cathode connected to the terminal a.

The timer circuit 3 operates with a slight time limit even when the output voltage of the preamplifier 1 is low, and operates so that the time limit operation becomes longer as the output voltage of the preamplifier 1 increases.

Reference numeral 4 denotes a drive circuit, which includes an operational amplifier 40 that operates as a buffer amplifier, and a relay 42 whose operation is controlled via a transistor 41 that operates based on an output signal derived from the operational amplifier 40.

The operational amplifier 40 has a resistor 43 connected between the non-inverting input section and the output section, and the non-inverting input section is grounded via a resistor 44.

Further, the transistor 41 has its emitter grounded, its base grounded via a resistor 45, and connected via a resistor 46 to the output section of the operational amplifier 40.

In the relay 42, a relay coil 47 has one end connected to the collector of the transistor 41, and the other end connected to one of the capacitors 23 and the diode 2.
4 and one of the resistors 21.

The other end of the capacitor 23 is grounded, and the other end of the resistor 21 is grounded via a Zener diode 22. The anode side of the Zener diode 22 is grounded.

The anode side of the diode 24 is connected to the terminal c and also to the terminal d via a relay contact 48 activated by excitation of the relay coil 47.

Terminal c is connected via an ignition switch 100 to the other side of a DC power supply 101 whose one end is grounded, and is also grounded via a relay switch 102 and a glow plug 103.

104 is a relay coil, which is connected in parallel with the pilot lamp 105 and has a terminal d.
and ground.

A relay 106 is configured by a relay coil 104 and a relay contact 102.

Reference numeral 5 denotes a reset signal generating circuit, which is constructed so that when the regulator switch 6 connected to the terminal e is activated, it derives a reset signal and stops the operation of the drive circuit 4.

50 is a resistor, one of which is connected to the terminal a, and the other is grounded via a resistor 51 and connected to the inverting input section of the operational amplifier 52.

The non-inverting input part of the operational amplifier 52 is grounded via a resistor 53 and a capacitor 54 connected in parallel, and a resistor 55 and a diode 5 connected in series.
6 to the terminal e, and via a resistor 57 to the output section of the operational amplifier 52.

58 is a resistor, one of which is connected to terminal a and the other is grounded through a resistor 59, and connected to the inverting input of the operational amplifier 40 in the drive circuit 4, and connected to the reset signal generating circuit 5 through a diode 60. It is connected to the output section of the operational amplifier 52.

The diode 60 has its cathode connected to the inverting input of the operational amplifier 40, and the diode 56
connects the anode to terminal e.

Terminal e is grounded via regulator switch 6 and connected via pilot lamp 7 to terminal c.

The regulator switch 6 is normally closed, but is configured to open when the engine is operated.

Note that the operational amplifier 34 in the timer circuit 3
The output part of the operational amplifier 40 in the drive circuit 4 is connected to the non-inverting input part of the operational amplifier 40 through a resistor 49.

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 ignition switch 100 is OFF, the engine (not shown) is stopped, the relay 42 is not activated, the relay 106 is not activated, and the glow plug 103 is not energized.

At this time, the thermistor 18 has a resistance value that corresponds to the radiator water temperature. Furthermore, when the engine is stopped, regulator switch 6
It's on. Further, in the timer circuit 3, the capacitors 30 and 54 are in an uncharged state.

In this state, I will now turn on the ignition switch 100.
When turned on, operational amplifiers 10, 34, 52, and 40 start operating.

The preamplifier 1 derives an output voltage according to the resistance value of the thermistor 18, in other words, the radiator water temperature.

At this time, the capacitor 30 in the timer circuit 3 starts charging.

By the way, the preamplifier 1 is set so that even when the radiator water temperature is extremely low, the potential of the non-inverting input part of the operational amplifier 34 is slightly higher than the potential of the inverting input part when the capacitor 30 is in an uncharged state or starts charging. Therefore, the timer circuit 3 always derives an H level output potential at the same time as the start of operation.

As a result, the operational amplifier 40 also derives an H level output signal, turns on the transistor 41, energizes the relay coil 47, and turns on the relay contact 48. Therefore, the relay coil 104 is energized, turning on the relay contact 102, and the glow plug 103 is energized.

If the thermistor 18 is a negative characteristic thermistor, the potential at the terminal b will be high if the radiator water temperature is high. Preamplifier 1 therefore derives a low output voltage.

Therefore, the potential difference between the inverting input part and the non-inverting input part of the operational amplifier 34 becomes small, and as the charging voltage of the capacitor 30 increases, the operational amplifier 34
The potential at the inverting input of the circuit quickly exceeds the potential at the non-inverting input. As a result, the potential of the output section of the operational amplifier 34, which is the output section of the timer circuit 3, becomes L.
As a result, the potential at the output section of the operational amplifier 40 in the drive circuit 4 also becomes the L level, turning off the transistor 41. Therefore, the relays 42 and 106 are deactivated, and the glow plug 103
Stop energizing.

Pilot lamp 105 is relay coil 104
is energized when energized.

By the way, since the regulator switch 6 is in the ON state when the engine is not started, the capacitor 54 in the reset signal generating circuit 5 is in an uncharged state. Since the potential at the inverting input part of the operational amplifier 52 is biased by the output voltage of the voltage dividing circuit of the resistors 50 and 51, the potential at the output part of the operational amplifier 52 at this time is at L level. When the engine starts, the regulator switch 6 is turned off, the capacitor 54 is charged, and the operational amplifier 52 outputs an H level output signal.

Therefore, the drive circuit 4 is connected to the reset signal generation circuit 5.
When the timer circuit 3 derives an H level output signal or when the timer circuit 3 derives an L level output signal, the glow plug 103 is operated to stop being energized.

Here, when the radiator water temperature is low, the resistance value of the thermistor 18 increases, so the potential at the terminal b decreases and the potential at the output section of the preamplifier 1 increases.
As a result, the operating time limit of the timer circuit 3 becomes longer. In other words, when the radiator water temperature is high, the glow plug 103 is energized and heated for a short time, and when the radiator water temperature is low, it is energized and heated for a long time.
Moreover, since a thermistor is used, the operation time of the timer circuit 3 is, for example, 5 seconds to 5 seconds when the radiator water temperature is in the range of -20° to 30°, as shown in Figure 2.
Can be varied continuously within a range of 30 seconds. According to the present invention, the glow plug 103 can be operated for an appropriate amount of time to start the engine.

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

The radiator water temperature is continuously detected by a thermistor, and the glow plug is activated only at the most suitable time to start the engine via a timer circuit and drive circuit that operate only for a time corresponding to the radiator water temperature. Glow plugs can be activated. In addition, by interposing resistors between the output section of the operational amplifier in the preamplifier, the positive electrode side of the DC power supply, and the negative electrode side of the DC power supply, and setting upper and lower limits for the output of the preamplifier, upper and lower limits of the engine preheating time can be set. Since the value can be set, it is possible to save power by not preheating for an unnecessarily long time at low temperatures, and at high temperatures, it is possible to preheat for a predetermined time after turning on the ignition switch to prevent the operator from detecting equipment malfunctions. Misidentification can be prevented.

In addition, only one thermistor is required, which reduces the number of assembly steps. Furthermore, since it is equipped with a reset signal generation circuit that is linked to the operation of the regulator switch, the glow plug operation can be stopped immediately after the engine starts, so that no power is wasted. Furthermore, since the preamplifier, timer circuit, and drive circuit are configured to include operational amplifiers, strict and proper operation can be achieved.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing a preferred embodiment of the glow plug timer for diesel vehicles according to the present invention, and FIG. 2 is a characteristic diagram showing the energization time t to the glow plug with respect to the radiator water temperature. 1...Preamplifier, 18...Thermistor, 3...
...Timer circuit, 4...Drive circuit, 5...Reset signal generation circuit, 6...Regulator switch,
100... Ignition switch, 103... Glow plug, 10, 34, 40, 52... Operational amplifier.

Claims (1)

[Scope of utility model registration request] It consists of a thermistor that detects the radiator water temperature, a resistor and an operational amplifier to derive an output voltage according to the radiator water temperature detected by the thermistor, and the positive electrode side of the DC power supply, the negative electrode side of the DC power supply, and the output section of the operational amplifier. A preamplifier that sets the upper and lower limits of the output voltage by a voltage divider circuit consisting of a resistor interposed between the two and a resistor element inside the operational amplifier, and a capacitor that starts charging when the ignition switch is turned on. A timer circuit that derives a pulse output with a width corresponding to the output voltage from the preamplifier and operates the timer; a reset signal generation circuit that is provided on the output side of the timer circuit and that derives a reset signal when the regulator switch is activated; The reset signal stops the operation and turns on the drive circuit that controls power supply to the glow plug and the ignition switch.
1. A glow plug timer for a diesel vehicle, comprising: a glow plug that starts operating when the timer circuit has elapsed and stops operating when the timer circuit derives an output after a certain period of time.