JPS59164918A - Moisture detecting alarm of fuel filter for vehicle - Google Patents

Abstract

PURPOSE:To make it possible to clearly display a moisture storage state to a driver, by immediately changing over an alarm lamp from dark to light by abruptly raising a lamp current when a detection current reaches a definite value. CONSTITUTION:When water is successively accumulated in a water sump 14, a water detecting element 13 detects a water accumulated state and a resistance value is successively lowered to generate a detection current corresponding to a water amount and said current is applied to the base of a transistor TR1 while converted to a voltage value by resistors R1, R2. A Zener diode ZD1 and a Zener current limiting resistor R5 are provided to the emitter side of TR1 and arbitrary reference voltage is applied to the emitter side of TR1. TR1 is brought to continuity when the potentials of the base and the emitter of TR1 come to the same potential and, succeedingly, TR2 is also brought to continuity while a power source 16 is supplied to an alarm lamp L to clearly light the same. By this mechanism, a moisture storage state is clearly displayed to a driver.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a moisture detection alarm device that electrically detects when a certain amount of moisture has accumulated in the lower part of a fuel filter and issues an alarm.

Examples of fuel filters conventionally used for vehicles include:
The structure for a diesel engine is shown in FIG. 1. A fuel filter 1 shown as a whole includes a cylindrical filter element 2, a filter case 3 housing this filter element 2, and 1. An intake passage 4a is attached to the upper part and introduces fuel into the outer periphery of the filter element 2, and an outlet passage 4b leads the fuel f+ out from the inner periphery of the filter element 2.
The upper cover 4 is designed so that the fuel introduced from the fuel tank 5 into the filter case 3 is filtered by the filter element 2 and sent out to the engine 6 side. In the figure, 7°8 is the fuel intake hose and intake hose connector that connects the fuel R tank 6 and the upper cover 4, 9 and 10tt--the upper cover 4 and the engine 6 are connected--m a cm hose and the discharge hose connector,
11 is a coil subring 8 that pushes the filter element 2 above the filter case 3; 12 is a drain cock attached to the bottom of the filter case 3; and 13 is a water sensor attached to the drain cock 12. The water sensor 13 is equipped with a water detection element 13aY on its head, and is configured to detect a rise in the water level and display an indication using an alarm lamp or the like.

The normal alarm lamp drive circuit employed in the above device has a circuit configuration as shown in FIGS. 2 and 3.

That is, 14 is a water reservoir, and the water detection element 135
is placed inside the water reservoir 14. I'm here. The resistors Fr, Rt and the capacitor C1π form a delay circuit section, and the transistors TR, , TR, π form an amplifier. The melon is the base current limiting resistor of the transistor TR, and R8 is the emitter current limiting resistor, so that the transistor TR1 acts as a transistor for amplifying the detection current of 13a (13a), and TR increases the alarm output current. It will work as a width transistor. Zl is a surge absorbing star, Dl is a surge absorbing and reverse current prevention diode, and L is a warning lamp. a, b, c,
d is an alarm lamp drive circuit 15 and a power supply 16. Terminals for connecting the alarm lamp L, water reservoir 14, etc. are shown.

The operation of a conventional alarm lamp drive circuit like the above σ is as follows.
) is true.

That is, when primary water is stored in the water reservoir 14, the resistance value of the water detection element 13a decreases, and the detection value according to the amount of water decreases.
When the current is applied to the base of the transistor TR through the base current limiting resistor, the collector current of the transistor TR increases sequentially to the base of the transistor TR. In addition, the conduction of the transistor TR9 starts energizing both ends of the alarm lamp L, turning it on. The capacitor acts as a current-voltage conversion resistor, and together with the capacitor C, it functions as a delay circuit, or in other words, a kind of timer, so that when the alarm lamp L is turned off, there is a delay so that it is clear whether it is lit or not. The VC axis moves so as to

However, in the conventional alarm lamp drive circuit as described above, the amplifier outputs a current that lights up the alarm lamp L in proportion to the magnitude of the detection current of the water detection element that detects moisture in the water reservoir 14. Therefore, as seen in the characteristic diagram of Fig. 4, the lamp current increases gradually based on the increase in the detection current.In other words, the detection current and the lamp current have a substantially linear relative relationship. The disadvantage is that it is difficult to determine the lighting state of the lamp. In other words, when considering the above operation as a phenomenological vc, the F3Aa of the alarm lamp L changes steplessly from "dark" to "bright" as the moisture in the water reservoir 14 rises ◇. Therefore, there is no standard for determining l:Φ in the driver's visual inspection, and on the contrary, the water accumulation situation becomes unclear, causing the driver to feel anxious.

The present invention solves the drawbacks of the conventional fuel filter moisture detection alarm, and provides an alarm signal using an alarm lamp or the like. The purpose is to provide a device that can clearly inform the driver of the moisture accumulation status by clearly outputting a signal, and its gist is that the moisture detection current exceeds a preset value. When the alarm output current is suddenly output Φ
If the alarm device is activated in such a way that moisture has accumulated.
An object of the present invention is to provide a device equipped with circuit means that immediately informs a driver.

Embodiments of the present invention will be described below with reference to the drawings. Fifth
In the circuit configuration π according to the present invention shown in FIGS. That is, 14 is a water reservoir, and the water detection element 13α is arranged in the water reservoir 1417'3. R
□ is a resistor for current-voltage conversion, and a capacitor C
Together with □, it forms a delay circuit. , R+2 is a transistor TR10 base current limiting resistor, and R+2 is a collector current limiting resistor. On the emitter side of the transistor TR, a Zener diode ZD is provided, one end of which is connected to the power supply line, and a Zener current limiting resistor R is provided.
, form a reference voltage generator with A. TR is a transistor for amplifying the alarm output current, and its base is connected to the intermediate portion between the collector current limiting resistor and the base bias resistor of the transistor TR. Z, &! A varistor for surge absorption, D□ is a diode for surge absorption and reverse current prevention, and L is a warning lamp.

α+ b+ C* d indicates a terminal for connecting the alarm lamp drive circuit 17 to the power source 16, the alarm lamp L, the water reservoir 14, and the like.

Figure @6 is a block diagram of the circuit elements shown in Figure 5 above, where the resistor t1 and the circle correspond to the current-voltage converter 18π, and the transistor TR1 corresponds to the voltage comparator 19. , the Zener diode ZD, the resistor, and the Lt reference voltage generator 20, the transistor Tya corresponds to the amplifier 21π, and the surge absorbing varistor Z4 and the diode D correspond to the surge absorber 22vc.

The operation of the alarm lamp drive circuit according to the present invention is as follows. That is, when water accumulates in the water reservoir 14, the water detection element 13α detects this, and its resistance value decreases sequentially to generate a detection current corresponding to the amount of water, and the resistors R, , I (
, [Thus, it is converted into a voltage value and applied to the base of the transistor TR□. On the emitter side of this transistor TR, there is a Zener diode Z connected at one end to the power supply line to obtain a preset constant voltage 1.
D1 and the Zener current limiting resistor, any reference voltage can be applied to the emitter side of the transistor TR□ by selecting the Zener diode ZD1. Therefore, n applied to the base of the transistor TR,
Unless the voltage at
Conversely, when the potentials of the base and emitter of the transistor T1 become the same, the transistor TR becomes conductive and the base ff current of the amplifying transistor TR2 flows. Therefore, the transistor TR1 functions as a comparator between the base side potential and the emitter side potential. On/off control will be performed. Therefore, due to the conduction π of the transistor T, both ends of the power supply 16 and the alarm lamp L are connected through the surge absorbing diode D1, and the alarm lamp L is clearly lit.

Figure @7 is a characteristic diagram showing the relationship between the detection current and the alarm output current, in other words, the lamp current, in the circuit configuration disclosed by the present invention, in which when the detection current reaches a certain value, the lamp current (7 ) Since the rising force 1 is sudden, the warning lamp L immediately switches from "dark" to "bright" π to clearly indicate to the driver the state of water accumulation.

In the present invention described above, the detection current and the reference voltage can be arbitrarily set by selecting the resistor and the Zener diode α], so they are appropriately determined according to the detection criteria for the water stored in the water reservoir 14. It is easy to do. Furthermore, since the reference voltage is generated in an internal circuit, there is an advantage that the detection characteristics are extremely stable without being influenced by external voltage fluctuations. Since the transistor T□ operates as a kind of switching element using the water detection element 13cL and the reference voltage, it is possible to make full use of the good switching characteristics peculiar to the transistor, and eliminates the sensitivity of the conventional slow characteristic change. It is effective to use π to change the characteristics. The driver's warning lamp is "dark"
You can see that the σ has suddenly changed from the state to a high-intensity "bright" state, so you can immediately operate the drain cock of the fuel filter to drain the water.The lighting state of the VC warning lamp is not clear as in the past. Coupled with the advantage of being able to eliminate the feeling of anxiety under certain circumstances, the use of a moisture detection alarm for vehicle fuel filters is highly effective.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing an example of the structure of a vehicle fuel filter, Fig. 2 is a circuit diagram showing a conventional alarm drive means Y,
3 is a block diagram showing the concept of the circuit diagram shown in FIG. 2, FIG. 4 is a characteristic diagram of the circuit shown in FIG. 2, FIG. 5 is a circuit diagram showing the alarm driving means of the present invention, and FIG. 6 is a block diagram showing the concept of the circuit diagram shown in FIG. 5, and FIG. 7 shows a characteristic diagram of the circuit shown in FIG. 5, respectively. 13α...Water detection element, 14...Water reservoir, 1
6...Power supply, 17...Alarm lamp drive circuit, 18.
・・Current-voltage converter, 19...Voltage comparator, 2o・
... Reference voltage generator, 21... Amplifier, 22... Surge absorber.

Claims (1)

[Claims] (1) In a moisture detection alarm device that includes a water reservoir at the bottom of the fuel filter and electrically detects that a certain amount of moisture has accumulated in the water reservoir circle to drive an alarm device,
A water sensor disposed in the water reservoir and configured to detect that a certain amount of water has accumulated; a current-voltage converter configured to convert the detected current of the water sensor into a voltage value; and a current-voltage converter connected to a power source. a reference voltage generator provided to obtain a constant voltage value set in advance; and a voltage comparator that generates an alarm signal by comparing the output of the current-voltage converter and the output from the reference voltage generator. , consisting of an amplifier connected to this voltage 1 comparator and an alarm device driven by the output of the amplifier,
Moisture in a fuel filter for a vehicle, characterized in that when the output voltage of the current-voltage converter exceeds a predetermined voltage, the voltage comparator issues an alarm signal to drive an alarm device. Detection alarm.