JPH045730Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a fuel filter device provided in a fuel supply system of a diesel engine.

BACKGROUND OF THE INVENTION Fuels that are mainly composed of light oil and are used as diesel engine fuels tend to deposit wax at low temperatures, for example, below about -10° C., and this tends to adhere to fuel filter elements and cause clogging. When such a phenomenon occurs, the flow of fuel supplied to the engine is cut off, resulting in inconveniences such as insufficient engine output, stopping, and stalling or stopping of the vehicle.

Therefore, a portion of the fuel that is heated by the mechanical work of the injection pump and overflows from the injection pump is introduced into the supply passage that leads the fuel from the fuel tank to the injection pump, and the temperature of the low-temperature fuel in the supply passage is increased. This prevents wax from precipitating from the fuel and prevents the filter element from clogging.

As an example of a technique for preventing such clogging of filter elements, a technique disclosed in Japanese Patent Application Laid-Open No. 18058/1983 is known. As shown in FIG. 7, this prior art mixes the fuel overflowing from the injection pump 50 with a gas-liquid separator, a heated fuel passage, and a temperature-sensitive valve device that opens and closes the passage depending on the fuel temperature. It is introduced into the valve 51 and further supplied to the upstream side of the filter element 53 via the mixing valve 51 and the conduit 52.

Problems to be Solved by the Invention However, in such a conventional technique, the mixing valve 51 equipped with a temperature-sensitive valve device and the filter element 53 are separate bodies, and both are connected to the conduit 5.
2, when the ambient temperature is extremely low, the heat of the fuel flowing through the conduit 52 is easily removed, the temperature of the fuel supplied to the filter element 53 decreases, and the temperature of the fuel flowing through the conduit 52 decreases.
It has been pointed out that there is a risk that the clogging prevention effect of

The present invention has been devised for the purpose of solving the problems of the prior art.

Means for Solving the Problems That is, the present invention has a filter element installed in a supply passage that supplies fuel to an injection pump, and a part of the fuel that is heated by the injection pump and overflows through the gas-liquid separation device. A heating fuel passage introduced through the heating fuel passage, and a temperature-sensitive valve device interposed in the heating fuel passage to open and close the heating fuel passage,
A fuel filter device for a diesel engine, wherein the heated fuel passage is connected to the upstream side of the filter element, the heated fuel passage and the filter element having the gas-liquid separation device and the temperature-sensitive valve device interposed therein. It is characterized by being integrated.

Effect: The amount of heat released from the fuel supplied to the filter element from the heating fuel passage is reduced.

Example Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a system diagram of a fuel filter device according to an embodiment of the present invention, in which fuel in a fuel tank 1 is filtered through a supply passage 2 by a fuel filter 3 according to the present invention, and then distributed, for example. The fuel is sucked into an injection pump 4 such as a type fuel injection pump. The injection pump 4 is equipped with a feed pump and a pressure regulator, and the fuel sucked by the feed pump is maintained at an appropriate pressure by the pressure regulator and is used to lubricate and cool various moving parts. guided to the pump section.

The fuel sucked into the pump section is distributed under pressure and guided to an injection nozzle 5 disposed in each cylinder of the diesel engine, where it is injected and supplied.

Surplus fuel that is not used for injection and injection pump 4
The fuel inside is returned to the fuel tank 1 through return passages 6a, 6b, 6, and 7, respectively. This overflow fuel is heated and raised in temperature by the mechanical work of the injection pump 4, and the heat is normally radiated in the fuel tank 1.

Reference numeral 8 denotes a gas-liquid separation and non-return device installed in the return passages 6 and 7, and this gas-liquid separation and non-return device 8 is connected to the second
It is attached to the upper cover 9 of the fuel filter 3 shown in the figure, and its details will be explained based on FIGS. 1 and 3.

That is, this gas-liquid separation/return check device 8 includes a lower float chamber 10 recessed in the upper cover 9 of the fuel filter 3, and an upper float fixed to the lower float chamber 10 via a gasket 11. The chamber 12 constitutes a float chamber 13, and a float 14 is housed in the float chamber 13 in a vertically movable manner. And this float chamber 1
A return passage 6 extending from the injection pump 4 is connected to the upper part of the float chamber 1.
One end of a return passage 7 extending from the fuel tank 3 to the fuel tank 1 is connected thereto. And this return passage 7
At the connection part between the float chamber 13 and the float chamber 13, the float chamber 1
A check valve 15 is provided to allow fuel to flow from fuel tank 1 to fuel tank 1 . On the other hand, an outlet port 18 is formed at the bottom of the float chamber 13 , which is connected to an inlet 17 of the fuel filter 3 via a heated fuel passage 16 . When the overflowing fuel from the injection pump 4 flows into the float chamber 13 of the gas-liquid separation/return check device 8 configured in this way, gas-liquid separation is performed here due to the difference in specific gravity.
Only the fuel with bubbles at the top is checked at check valve 1.
5 is pushed open and discharged into the fuel tank 1, and only fuel without air is discharged from the outlet port 18 into the heated fuel passage 16. Float chamber 13
When the amount of fuel stored in the fuel filter 3 falls below a predetermined value, the float 14 descends with the liquid level and closes the outlet port 18, so that fuel containing air will not flow into the fuel filter 3. Therefore, the temperature-sensitive valve device 24, which will be described in detail later, operates properly.

Next, details of the fuel filter will be explained based on FIGS. 1 and 2.

In the figure, a center pipe 20 is disposed in the center of the filter body 19, and a filter element 21 is disposed concentrically with the center pipe 20 between the center pipe 20 and the filter body 19. A supply port 22 connected to the supply passage 2 on the fuel tank 1 side and a discharge port 23 connected to the supply passage 2 on the injection pump 4 side are opened in the top cover 9 connected to the upper end of the filter body 19. and the supply port 22 is connected to the center pipe 20.
On the other hand, the discharge port 23 communicates with the downstream side of the filter element 21. Therefore, the fuel is led from the supply port 22 to the center pipe 20, filtered there from the lower end via the filter element 21, and then led to the injection pump 4 from the discharge port 23, and is then heated. The heated fuel sent through the fuel passage 16 is led to the upstream side of the filter element 21.

Reference numeral 24 denotes a temperature-sensitive valve device, and as shown in FIGS. A valve body 25 accommodated in a reciprocating manner, a coiled shape memory alloy spring 27 that contacts the flange portion 26 of this valve body 25 and biases the valve body 25 in the valve closing direction, and this shape memory alloy spring. 27 and a coil-shaped bias spring 28 that urges the valve body 25 in the valve opening direction. The shape memory alloy spring 27 of this temperature-sensitive valve device 24 acts as a compression spring.
When the ambient temperature or fuel temperature around the temperature-sensitive valve device 24 rises above T ₁ (for example, -10°C), it expands by itself (changes in phase) and compresses the bias spring 28, closing the valve body 25. direction, the temperature is T ₂
When the temperature reaches 40° C., for example, the valve body 25 is pressed against the valve seat 29 to close the valve (see FIG. 6). By this,
The flow of fuel from the heating fuel passage 16 to the supply passage 2 is cut off. On the other hand, this shape memory alloy spring 27
The spring force begins to decrease when the ambient temperature or fuel temperature drops below a predetermined temperature, and the spring force begins to decrease when the temperature reaches T ₂ (e.g. 40
℃), the valve body 25 is compressed by the spring force of the bias spring 28, and the valve body 25 is therefore pressed by the bias spring 28 and starts the valve closing operation. Further, when the temperature further decreases to T ₁ (for example, −10° C.), the valve body 25 becomes almost completely in the open position. As a result, the relatively high temperature fuel in the heated fuel passage 16 is introduced into the supply passage 2 through the inlet 17, mixed with the low temperature fuel in the supply passage 2, and flows into the fuel filter 3. The temperature of the incoming fuel increases. As a result, wax can be prevented from being deposited from the fuel, and the filter element 21 can be prevented from clogging.

As described above, since the temperature-sensitive valve device 24 controls the opening and closing operations by utilizing the shape memory effect of the shape memory alloy spring 27 used therein, the temperature-sensitive valve device 24 controls the opening/closing operation by utilizing the shape memory effect of the shape memory alloy spring 27 used therein. By selecting the transformation temperature of the alloy spring 27 and the spring forces of the shape memory alloy spring 27 and the bias spring 28, a desired operation start position (temperature) can be set. Note that 30 is a fuel passage formed with a notch in the flange portion 26 of the valve body 25, and the fuel flowing into the heated fuel passage 16 from the outlet port 18 flows through this fuel passage 30. Further, 31 is a plug, and this plug 31 is screwed onto the opening end of the heating fuel passage 16 via a seal washer 32 in order to close the opening end of the heating fuel passage 16.

In FIG. 2, 33 is an overflow passage that bypasses the supply port 22 and the discharge port 23 without passing through the filter element 21;
Check valve 34 in overflow passage 33,
35 is interposed. Therefore, when the filter element 21 becomes clogged, the fuel pressure on the supply port 22 side increases and the check valves 34, 35 are opened to guide the fuel flow to the injection pump 4 without being filtered, thereby preventing the engine from stopping. 36 is a manual pump for venting air from the fuel line; 37 is a water separator that separates and stores water based on the difference in specific gravity; 38 is a water level sensor that detects the water level accumulated in the water separator 37 and gives a warning; It's a draining pot.

Moreover, in this embodiment, as shown in FIG. 6, T ₁ =
The alloy composition of the shape memory alloy spring was selected so that the temperature was -10℃ and T ₂ = 40℃, but the selection of the composition of the shape memory alloy spring is not limited to this, depending on the usage environment. T ₁ and T ₂ can be set.

As is particularly clear from FIG. 3, the present embodiment configured as described above includes a gas-liquid separator/return device 8, a heated fuel passage 16 in which a temperature-sensitive valve device 24 is interposed, and a filter element 21. Because they are integrated, it is difficult for the heat of the fuel supplied from the heating fuel passage 16 to the filter element 21 to be lost.
The amount of heat released from the fuel can be reduced. Therefore, according to this embodiment, even when used in an extremely low temperature atmosphere, wax can be prevented from being deposited from the fuel, and the filter element 21 can be prevented from clogging even more effectively.

Effects of the invention As described above, the present invention has a filter element installed in the supply passage that supplies fuel to the injection pump, and a part of the fuel that is heated by the injection pump and overflows through the gas-liquid separation device. The heated fuel passage introduced by the heated fuel passage and the temperature-sensitive valve device installed in the heated fuel passage to open and close the heated fuel passage are integrated. The heat of the supplied fuel is not taken away by low-temperature outside air, etc., and the temperature of the fuel is prevented, making it possible to more effectively prevent clogging of the filter element, further increasing the reliability of this device. can be improved.
In addition, the fuel filter device equipped with the temperature-sensitive valve device can be made smaller and lighter, and the manufacturing cost can be reduced.

[Brief explanation of the drawing]

Fig. 1 is a system diagram of a fuel filter device showing an embodiment of the present invention, Fig. 2 is a sectional view of the same fuel filter,
Figure 3 is an enlarged sectional view along the - line in Figure 2, Figure 4 is an enlarged view of the main part of Figure 3 (when the temperature-sensitive valve device is closed), and Figure 5 is the temperature-sensitive valve device in Figure 4. 6 is a temperature-flow characteristic diagram of a temperature-sensitive valve device, and FIG. 7 is a system diagram of a conventional fuel filter device. 2... Supply passage, 4... Injection pump, 16...
Heating fuel passage, 21...Filter element, 2
4...Temperature-sensitive valve device, 25...Valve body, 27...
Shape memory alloy spring, 28...bias spring.

Claims (1)

[Scope of utility model registration request] A filter element installed in a supply passage that supplies fuel to the injection pump, a heating fuel passage through which a portion of the fuel that is heated by the injection pump and overflows is introduced via a gas-liquid separator, and this heated fuel passage. A fuel filter device for a diesel engine, comprising: a temperature-sensitive valve device interposed in a heated fuel passage to open and close the heated fuel passage; and the heated fuel passage is connected to an upstream side of the filter element. A fuel filter device for a diesel engine, characterized in that a gas-liquid separation device, a heating fuel passage in which a temperature-sensitive valve device is installed, and a filter element are integrated.