JPS62113861A - Fuel filter apparatus - Google Patents

Abstract

PURPOSE:To save the power by detecting the displacement at a movable section occurring in accordance with the pressure variation at the outlet section of a fuel filter so as to decide the clogging of wax and supplying power to a heating apparatus for regenerating the filter only when a filter is clogged with wax. CONSTITUTION:In a fuel filter apparatus where the fuel enters through a fuel inlet section 3 and pass through a filter 2 and discharged through a fuel outlet section 4, the differential pressure between the inlet and outlet sections 3, 4 will increase gradually upon clogging of the filter 2 and the diaphragm 10 of a differential pressure detector 8 is displaced to the right. When said differential pressure reaches a setting level, a reed switch 13 is turned on. While the displacement of the diaphragm 10 is detected as a voltage variation by means of a displacement detector 16 and the detected signal is differentiated by means of a wax clogging decision unit 24. When the variation of said displacement exceeds a predetermined level, it is decided that clogging with wax has occurred then the relays 22, 23 are energized and the power is fed to a heating device 7 for fusing the wax.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel heating type fuel filter device that performs heating only for clogging caused by wax.

[Prior Art] FIG. 2 shows a conventional fuel heating type fuel filter device used in a diesel engine. In FIG. 2, a fuel inlet section 3 is located at the top of a filter case 1 that houses a filter 2.
A fuel outlet section 4 is formed, and a fuel flow path is formed from the inlet section 3 to the outlet section 4 with a filter 2 interposed therebetween.

Further, a heating device 7 is disposed in the middle of the fuel flow path, and the heating device 7 is configured so that it can be energized from electricity a (+V) via a relay contact 101a of a relay 101. When energized, the heating device 7 generates heat. Entrance part 3
A differential pressure detector 8 having a built-in diaphragm 10 having a magnet 1'1 and a reed switch 13 installed so as to act as necessary between the diaphragm 10 and the magnet 11 is provided between the diaphragm 10 and the outlet part 4. It will be done. The reed switch 13 is connected in series with the relay coil 101b of the relay 101 between the power supply (+V) and ground.

According to the above configuration, when the filter 2 is not clogged with wax, the pressure difference between the inlet section 3 and the outlet section 4 is within the allowable range, so the diaphragm 1o is held at a position that keeps the reed switch 13 in the OFF state. be done. but,
When clogging with wax occurs and the pressure difference between the inlet section 3 and the outlet section 4 exceeds a set value, the diaphragm 10 is displaced and the reed switch 13 is turned on by the action of the magnet 11. When reed switch 13 turns on, relay 1
The heating device 7 is energized by the ON operation of 01, and the heat melts the wax adhering to the filter 2 and eliminates clogging.

In diesel engines, semi-solid wax precipitates in the fuel in cold regions during the winter, and this can clog the fuel filter while driving and cause the engine to stop.
This can be prevented by the fuel filter device as described above.

[Problems to be Solved by the Invention] However, clogging that occurs in the filter 2 is not always caused by wax, and clogging may also occur due to, for example, sludge. Even when such clogging occurs, the same effect as described above occurs in the fuel filter device and the heating device 2 generates heat, but the clogging is not cleared because the clogging is caused by sludge. As described above, the conventional fuel filter device has the problem that power is wasted because the heating device 7 is energized even when the fuel filter is clogged with sludge.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fuel filter device in which the heating device is energized only when the filter becomes clogged due to wax in the fuel at low temperatures.

[Means for Solving the Problems] The fuel filter device according to the present invention includes a filter disposed in a fuel flow path between a fuel inlet and a fuel outlet, and a filter that heats the fuel and melts precipitated wax. a pressure detector for detecting a change in the pressure state at the fuel outlet as a change in differential pressure or negative pressure; and a pressure detector for energizing the heating device as necessary based on an output signal of the pressure detector and a switch element that performs the above-mentioned change in pressure, and a displacement detector that includes a movable part that displaces in response to the change in pressure and an element that senses the displacement of this movable part and outputs a displacement signal, and a displacement detector that outputs a displacement signal. A determining means detects the rate of pressure change based on the output signal and determines whether wax is clogged or not, and an output signal of the determining means.

[Function] In the present invention, the displacement detector and the determining device determine whether the filter clogging that has occurred is caused by wax or sludge, and only in the case of clogging by wax, the heating device is energized. I decided to do it.

[Example] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a longitudinal sectional view and an electric circuit diagram showing the configuration of a fuel filter device according to the present invention. The fuel filter device of the present invention focuses on the fact that clogging caused by wax progresses in a shorter time (within one hour) compared to clogging caused by sludge, and based on this characteristic, clogging caused in the filter is caused by wax. It is configured to determine whether the problem is caused by sludge or by sludge.

In Fig. 1, 1 is a bottomed cylindrical filter case;
A filter 2 is provided in the center of the filter case 1, a fuel inlet 3 and a fuel outlet 4 are provided in the upper part, and a level warning switch 5 is provided in the lower part. As shown by the arrow in the figure, the fuel flows into the inlet section 3, passes through the central passage 6 to reach the lower part, passes through the filter 2, moves upward, and flows out from the outlet section 4. Arrows indicate fuel flow paths. Further, the level warning switch 5 is a float level sensor that senses the level of water separated by the filter 2.

A cavity is formed in the fuel flow path between the inlet section 3 and the central passage 6, and a heating device 7 is arranged in this cavity. The heating device 7 includes, for example, a PTC heater (Positive Te
mperature CoefficientTher
m i 5ter (approximately 8) is used.

A differential pressure detector 8 is provided above the filter case 1 . The differential pressure detector 8 has a chamber 9, and a diaphragm 1o is disposed in the center of the chamber 9 to form isolated left and right chambers. The left ventricle communicates with the inlet section 3, and the right ventricle communicates with the outlet section 4.

A support cylinder member 12 having a ring-shaped magnet 11 is attached to the left side of the diaphragm 10 in the figure, and arranged so that a reed switch 13 disposed outside the palm 9 and the magnet 11 interact with each other in a predetermined positional relationship. be done. On the other hand, a slider 15 is attached to the right side of the diaphragm 10 in the figure to change the resistance value of a resistor 14 disposed in the right chamber. The resistor 14 and the slider 15 constitute a displacement detector 16, which detects the displacement of the diaphragm 1o caused by the pressure difference between the inlet section 3 and the outlet section 4.

Next, the configuration of the electric circuit will be explained. , 21 is a power terminal, 2
2 is a first relay, 23 is a second relay, and 24 is a wax clogging detector. Relay 22 is relay coil 22
The relay 23 consists of a relay coil 23a and relay contacts 23b and 23c. Between the power supply terminal 21 and the ground 25, the relay contact 22
b, the relay coil 23a, and the reed switch 13 are connected in series, and a relay contact 23c is connected in parallel to the relay contact 22b. Further, the low pile body 14, the floor mover 15, the wax clogging determiner 24, and the relay coil 22a are connected in series between the power supply terminal 21 and the ground 26. Further, a relay contact 23b and the heating device 7 are connected in series between the power supply terminal 21 and the ground 27.

FIG. 3 shows the circuit configuration of the wax clogging determiner 24.

The wax clogging determiner 24 is configured as a differentiating circuit by connecting an operational amplifier 28, capacitors C, C, and resistors R, R2 as shown.

The operation of the fuel filter device having the above configuration will be explained. When no clogging occurs in filter 2,
The diaphragm 10 in the chamber 9 is in a predetermined position since the pressure difference between the inlet section 3 and the outlet section 4 is normal, and keeps the reed switch 13 in the off state. When the filter 2 becomes clogged, the pressure at the outlet portion 4 gradually decreases below the normal value, so the pressure difference gradually increases, and the diaphragm 10 gradually displaces to the right in the figure. When the clogging progresses further and the pressure difference between the inlet section 3 and the outlet section 4 exceeds a set value, the magnet 11 approaches the position of the reed switch 13 and turns on the reed switch 13.

On the other hand, in the displacement detector 16, when the pressure difference between the inlet section 3 and the outlet section 4 changes as the clogging progresses, and the diaphragm 10 is displaced, this is detected as a change in the voltage at the resistor 14. The signal output from the displacement detector 16 is input to the wax clogging determiner 24. The wax clogging determiner 24 differentiates the signal given from the displacement detector 16, and outputs an output when the differential value is equal to or greater than a set value. That is, when the rate of change in the position of the diaphragm 10 is greater than or equal to the set value, it is determined that the filter 2 is clogged with wax and a pressure difference has occurred. Generally, clogging due to wax generation progresses in a short period of one hour or less, and clogging due to sludge shows almost no change in the clogging state within a short period of one hour or less. Therefore, if the differential pressure detector 8 detects a pressure difference due to the filter 2 being clogged, checking whether the differentiated output of the displacement detector 16 is greater than or equal to the set value will determine whether the clogging is due to wax. , it becomes possible to determine whether it is caused by sludge.

As described above, when the wax clogging detector 24 outputs an output and turns on the relay contact 22b, this relay contact 2
2b and the reed switch 13 which is already in the on state, current flows to turn on the relay 23. relay 2
When the relay contacts 23b and 23c are turned on by the ON operation of 3, the heating bag @7 is energized via the relay contact 23b. When the heating device 7 is energized, the fuel is heated, the wax is melted, and the filter 2 is unclogged. Furthermore, even if the rate of change of the output signal of the displacement detector 16 decreases and the output of the determiner 24 becomes O, the relay contact 23c is connected until the output of the differential pressure detector 8 becomes OFF. During this period, the relay 23 is held in the on state to continue supplying electricity to the heating device 7.

According to the above configuration, when the filter 2 is clogged with sludge, the output of the determiner 24 is held at 0 even if the differential pressure detector 8 outputs an ON output, so that the heating device 7 No electricity is applied.

In addition, in the case of clogging due to sludge, the differential pressure detector 8
It is also possible to configure the lamp on the dash board to be lit on condition that the output of the wax clogging detector 24 is on and the output of the wax clogging determiner 24 is off. According to this configuration, it is possible to notify the user that the filter 2 is due to be replaced due to clogging with sludge.

As another modified embodiment of the present invention, the following 4° configuration is also possible. In order to detect filter clogging, a negative pressure detector that determines the pressure difference between the atmosphere and the outlet section 4 can be used instead of the differential pressure detector 8. Although the voltage change in the resistor 14 is used as the displacement detector 16, it is also possible to use a capacitor instead and use the change in electric capacitance. Furthermore, wax clogging detector 2
4 can also be realized using a computer.

[Effects of the Invention] As is clear from the above description, according to the present invention, it is possible to discriminate between wax clogging and sludge clogging by using the clogging generation characteristics of the fuel heating type fuel filter device for diesel engines. Since the power supply to the heating device is controlled based on the command signal from the determining means, heating can be performed only in the case of wax clogging, and electric power can be used effectively and economical efficiency can be improved. It has the effect of being able to.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a fuel filter device according to the present invention. FIG. 2 is a configuration diagram of a conventional fuel filter device. FIG. 3 is a circuit diagram of the wax clogging detector. [Explanation of symbols] 1...Filter case, 2...Fuel inlet section, 3...Fuel outlet section, 7...Heating device, 8... ... Differential pressure detector, 10 ... Diaphragm, 16 ... Displacement detector, 22 ... First relay, 23 ... Second Relay, 24... Wax clogging detector. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A filter disposed between a fuel inlet and a fuel outlet, a heating device for heating the fuel, a pressure detector for detecting pressure changes at the fuel outlet, and a filter disposed between a fuel inlet and a fuel outlet; A fuel filter device comprising a switch element that energizes the heating device in response to an output signal from a pressure detector, the displacement detection comprising a movable part that displaces in response to the pressure change and an element that senses the displacement of the movable part. a determination means for detecting the rate of pressure change based on the output signal of the displacement detector and determining whether or not the wax is clogged; 1. A fuel filter device comprising a switch element that enables energization.