JPH0419380B2 - - 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.

<Prior Art> In fuels mainly composed of light oil used as fuel for diesel engines, wax precipitates at low temperatures, for example, about -10° C. or lower, and this tends to adhere to fuel filter elements and cause clogging. When this phenomenon occurs, the flow of fuel supplied to the engine is cut off, resulting in inconveniences such as insufficient engine output or stopping, stalling or stopping of the vehicle, and especially poor starting performance at low temperatures. There is a problem.

There are methods disclosed in JP-A-55-46093 and JP-A-60-164657 that attempt to eliminate such inconveniences.

An example of this is shown in FIGS. 5 and 6.

In FIG. 5, fuel in a fuel tank 1 is filtered through a fuel filter 3 through a supply passage 2, and then sucked into an injection pump 4 such as a distribution type fuel injection pump. The injection pump 4 is equipped with a feed pump and a pressure regulator, and the pressure regulator holds the fuel sucked by the feed pump at an appropriate pressure to lubricate and cool each moving part, and also supplies it to the pump part. lead

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

Here, in order to cool itself, the injection pump 4 takes in excess fuel in excess of the fuel required for injection, and this excess fuel is combined with surplus fuel sent to the injection nozzle 5 but not used for injection. is returned to the fuel tank 1 via return passages 6, 7, and 8.

This so-called 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.

As shown in FIG. 6, the gas-liquid separation and backflow prevention device 9 installed in the return passage 8 is equipped with a float chamber 11 having a built-in float 10, so that overflow fuel containing bubbles flows into the float chamber. 11, where gas-liquid separation is performed based on the difference in specific gravity,
Only fuel with bubbles at the top, check valve 1
2 is pushed open and released into the fuel tank 1. In the float chamber 11, when the stored amount of overflow fuel falls below a predetermined value, the float 10 descends with the liquid level and closes the discharge port 13 provided in the bottom wall. As a result, only overflow fuel with no air mixed in is led out from the discharge port 13.

The discharge port 13 of the float chamber 11 is connected to the heating fuel passage 1
4, it is connected to the inlet 3a of the fuel filter 3, and overflow fuel is guided into the fuel filter 3 to heat the fuel.

<Problems to be Solved by the Invention> However, in the conventional diesel engine fuel filter device, as described above, the gas-liquid separation and backflow prevention device 9 is configured completely independently from other devices. For example, since it is separated from the main body of the fuel filter 3, the following problems occur. That is, since each component device is located over a wide area, it is difficult to make the device compact, and installation space is often restricted when mounted on a vehicle, which impedes the ability to make the vehicle compact. Further, the fuel hose 14A, which constitutes the portion of the heating fuel passage 14 that connects the gas-liquid separation/backflow prevention device 9 and the fuel filter 3, has to be made longer. Therefore, the amount of heat radiated from the fuel hose 14A increases, and the overflow fuel is easily cooled while passing through the fuel hose 14A. As a result, even if overflow fuel with a raised temperature is supplied from the injection pump 4, the overflow fuel that has been cooled down to a low temperature will mix with the fuel in the fuel filter 3, and the fuel in the fuel filter 3 will be mixed with the fuel in the fuel filter 3. The original purpose of heating by mixing the heating fuel cannot be sufficiently achieved.
Heat is also dissipated from the main body of the gas-liquid separation and backflow prevention device 9. Furthermore, the total number of component parts is large, and the manufacturing cost is also high.

As described above, the conventional devices have problems in terms of characteristics and installation, and are also disadvantageous in terms of cost.

The present invention has been made in view of these conventional problems, and has a configuration in which a gas-liquid separation and backflow prevention device is integrated with a fuel filter, and by adopting a unique configuration for this integration. The purpose is to provide a configuration that is particularly advantageous in terms of characteristics, installation, and cost.

(Means for solving the problem) For this reason, the present invention includes a fuel filter interposed in the supply passage that supplies fuel to the injection pump,
In a fuel filter device for a diesel engine, the top cover of the fuel filter is provided with a supply port for fuel led from a fuel tank and a discharge port for fuel connected to an injection pump, wherein a space is provided in the top cover, and the space is connected to the top cover. A liquid level responsive member is housed in a float chamber formed by a cover disposed and attached to the upper part of the cavity, and a fuel discharge port communicating with the fuel tank via a backflow prevention means is provided in the upper part of the cover, and an injection A fuel inlet port connected to a heated fuel passage that guides a portion of fuel overflowing from a pump, injection nozzle, etc. to the fuel filter is provided, and the fuel inlet port is provided at the bottom of the float chamber and is opened and closed by the liquid level responsive member. A float indoor fuel discharge port and a temperature-sensitive valve device that detects a temperature of the fuel flowing through the supply port below a predetermined value and causes the fuel flowing out from the float indoor fuel discharge port to flow to the supply port are provided in the upper cover. The configuration is as follows.

<Operation> Fuel supplied from the fuel tank is filtered by a fuel filter and introduced into the injection pump, but when the fuel temperature drops below a certain temperature, wax components in the fuel precipitate, causing clogging of the fuel filter.

In such a case, the temperature-sensitive valve device detects this temperature and opens the valve, and a portion of the fuel overflowing from the injection pump, injection nozzle, etc. is guided to the inlet at the top of the cover via the heated fuel passage. The fuel flows into the float chamber, where gas-liquid separation is performed based on the difference in specific gravity, and only the fuel with bubbles is returned to the fuel tank via the backflow prevention means.

The overflow fuel from which bubbles have been separated in the float chamber is introduced into the fuel filter through the discharge port and the supply port. As a result, the temperature of the fuel introduced into the fuel filter increases, preventing the wax component from being deposited, and clogging the fuel filter.

In this way, the fuel filter incorporates a gas-liquid separation and backflow prevention mechanism that separates gas and liquid based on the difference in specific gravity of overflow fuel, making it possible to significantly reduce the distance between the float chamber and the temperature-sensitive valve device compared to conventional methods. It is possible to prevent overflow fuel from being cooled by heat dissipation during the journey from the float chamber to the temperature-sensitive valve device as much as possible, and the heat released from the gas-liquid separation and backflow prevention mechanism can be Since the fuel is efficiently absorbed into the fuel filter, the heated fuel can be supplied from the float chamber into the fuel filter at a high temperature.

Therefore, the original purpose of warming the fuel in the fuel filter by mixing the heated fuel can be fully achieved.

<Example> Hereinafter, an example of the present invention will be described based on FIGS. 1 to 4.

In FIG. 1, a fuel filter 15 is installed in a supply passage 2 that supplies fuel to an injection pump 4;
It is the same as the conventional one, and includes an injection pump 4 and a heating fuel passage 7A that guides a portion of the fuel overflowing from the injection nozzle 5 to the fuel filter 15.

A gas-liquid separation and backflow prevention device 16, which is installed in the heated fuel passage 7A on the upstream side of a temperature-sensitive valve device to be described later, is integrated with the fuel filter 15.

Here, the structure of the fuel filter 15 will be explained based on FIGS. 2 to 4.

A cylindrical filter element 18 is arranged in the center of the filter body 17 concentrically with a center pipe 19. A supply port 21 connected to the supply passage 2A on the fuel tank 1 side and a discharge port 22 connected to the supply passage 2B on the injection pump 4 side are opened in the top cover 20 connected to the upper end of the filter body 17. 21 is communicated with the center pipe 19, while the discharge port 22 is communicated with the downstream side of the filter element 18.

On the other hand, a cavity 23a is integrally formed in the atsupa cover 20, and the liquid level of the gas-liquid separation/backflow prevention device 16 is located in the float chamber 23 formed by this cavity 23a and a float chamber cover 24 disposed above the cavity 23a. A float 25 as a response member is housed.
The float chamber cover 24 is connected to the fuel tank 1 via a check valve 26 as a backflow prevention means.
a fuel discharge port 27 communicating with the heating fuel passage 7;
A fuel inlet 28 connected to A is provided.
A discharge port 29 having a float valve seat is provided in the bottom wall of the float chamber 23.
is communicated with the fuel passage 30. This fuel passage 30
is provided with a temperature-sensitive valve device 33 that detects that the temperature of the fuel flowing through the supply port 21 is below a predetermined value and causes the fuel flowing out from the discharge port 29 to flow into the supply port 21 . The temperature-sensitive valve device 33 mainly includes a check valve 31, a bimetal 32 for controlling opening and closing of the check valve 31, and a positioning and adjusting means for the bimetal 32.

That is, one end of this fuel passage 30 is communicated with the center pipe 19 together with the supply port 21 via a check valve 31, and the other end is closed by a blind plug 34.

The check valve 31 is pressed and positioned against the inner wall of the fuel passage 30 by the reaction force of a positioning spring 35 disposed within the fuel passage 30. The bimetal 32 is disposed so that its tip can press against and separate from the rod 31a of the check valve 31, and the other end of the bimetal 32 is
It is fixed to the top cover 20 with screws 36. Specifically, a passage 20a is formed in the boss portion 20A of the upper cover 20 to communicate the fuel passage 30 and the center pipe 19, and a stay 37 is fitted into the inner wall of the boss portion 20A and fixed by caulking. The lower end of the bimetal 32 is fixed with a screw 36. Further, an adjustment screw 38 is screwed into the stay 37 so that it can freely move forward and backward, and the position of the bimetal 32 is adjusted by this adjustment screw 38.

In FIG. 2, reference numeral 39 is an overflow passage that bypasses the supply port 21 and the discharge port 22 without passing through the filter element 18, and check valves 40 and 41 are interposed in the overflow passage 39. . Therefore, if the filter element 18 becomes clogged, the fuel pressure on the supply port 21 side increases and the check valves 40,
41 is opened to direct the fuel flow to the injection pump 4 without filtration to prevent the engine from stalling. 42 is a manual pump for venting air from the fuel line; 43 is a water separator that separates and stores water based on the difference in specific gravity; 44
numeral 45 is a water level sensor for sensing and warning the water level accumulated in the water separator 43; and 45 is a drain tank.

Next, the operation of this configuration will be explained.

The fuel sucked up from the fuel tank 1 is filtered by the filter element 18 of the fuel filter 15 and introduced into the injection pump 4 via the supply passage 2B, but when the fuel temperature falls below a certain temperature, wax components in the fuel precipitate. However, the filter element 18 becomes clogged.

In such a case, the temperature-sensitive valve device 33 using the bimetal 32 detects that the temperature of the fuel flowing through the supply port 21 is below a predetermined value, opens the valve, and allows the fuel flowing out from the discharge port 29 to flow into the supply port 21. Thereby, the heated fuel from the injection pump 4 is guided to the inlet 28 via the return passage 7 and the heated fuel passage 7A, and introduced into the float chamber 23. The overflow fuel flows into the float chamber 23, where it undergoes gas-liquid separation based on the difference in specific gravity, and only the fuel with bubbles in the upper part is returned to the fuel tank 1 by pushing open the check valve 26. The overflow fuel from which bubbles have been separated in the float chamber 23 is discharged from the discharge port 2.
9, and is introduced into the center pipe 19 through the open check valve 31 with minimal heat loss. This increases the fuel temperature, prevents the wax component from being deposited, and prevents the filter element 18 from clogging. Further, as the fuel temperature rises, the introduction of overflow fuel for heating the fuel gradually decreases because the opening area of the check valve 31 becomes smaller in accordance with the thermal deformation of the bimetal 32.

Furthermore, if the fuel temperature becomes higher than the set value,
The temperature-sensitive valve device 33 closes to stop the fuel flowing out from the discharge port 29 from flowing into the supply port 21, thereby cutting off the introduction of overflow fuel.

In the manner described above, proper fuel heating is performed.

According to this configuration, a float chamber 23 is provided in the upper cover 20 portion of the fuel filter 15 to house the float 25, and a fuel discharge port 27 communicating with the fuel tank 1 via the check valve 26 is provided in the upper cover 20 portion. , an inlet 28 connected to the heated fuel passage 7A is provided, and a discharge port 29 for the fuel in the float chamber 23, which is opened and closed by the float 25, is provided at the bottom of the float chamber 23, so that overflow fuel can be delivered to the fuel filter 15. Since a gas-liquid separator and backflow prevention device 116 is incorporated, which performs gas-liquid separation based on the difference in specific gravity of , it is possible to prevent the overflow fuel from being cooled by heat dissipation during the journey from the float chamber 23 to the temperature-sensitive valve device 33 as much as possible, and moreover, the heat released from the gas-liquid separation and backflow prevention device 16 is transferred to the fuel filter 15. Since the heated fuel is efficiently absorbed by the float chamber 23, the heated fuel can be supplied into the fuel filter 15 at a high temperature.

Therefore, the original purpose of warming the fuel in the fuel filter 15 by mixing the heated fuel can be fully achieved. By reducing the number of independently configured devices by one, it is no longer necessary to be subject to restrictions on the installation location when mounted on a vehicle, improving ease of mounting on a vehicle, and further reducing the risk of vehicle accidents. Since it is possible to reduce the number of items that can be damaged due to this, it is possible to reduce the frequency of damage caused by fuel system damage and improve safety. Furthermore, since the number of overall components is reduced, it is advantageous in terms of cost.

In particular, since the top cover 20 is provided with a supply port 21 for fuel led from the fuel tank 1, the float chamber 23 and components related to the float chamber 23 are integrally provided in the top cover 20. , float chamber 23 and fuel filter 1
The overflow fuel passage connecting to the supply port 21 of No. 5 can be formed shorter, and the above-mentioned effect of preventing heat dissipation is extremely well exhibited, as well as the effect of simplifying the device is extremely well exhibited. be.

<Effects of the Invention> As explained above, according to the present invention, conventionally,
For example, the gas-liquid separator and backflow prevention device, which was configured independently from other devices and was provided separately from the fuel filter body, has been incorporated into the fuel filter body and is now integrated, allowing leakage from the fuel piping and the device itself. The original purpose of heating the fuel in the fuel filter by mixing it with heating fuel can now be fully achieved, effectively preventing clogging of the fuel filter, and reducing the amount of heat generated at low temperatures. In addition to effectively improving the startability of the engine, many other effects can be obtained, such as improving vehicle mountability, reducing danger in the event of an accident, and reducing costs by reducing overall component parts.

In particular, since the top cover of the fuel filter is provided with a supply port for the fuel led from the fuel tank, by integrally providing the float chamber and components related to the float chamber in the top cover, the float chamber The overflow fuel passage connecting the fuel filter and the supply port of the fuel filter can be formed shorter, and the above-mentioned effect of preventing heat dissipation is extremely well exhibited, as well as the effect of simplifying the device is extremely well exhibited. There is an advantage.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing one embodiment of a filter device according to the present invention, Fig. 2 is a front cross-sectional view of a fuel filter in the same device, Fig. 3 is a side view of the same fuel filter, and Fig. 4 is the same as above. Cross-sectional view of the gas-liquid separation and backflow prevention device part in the fuel filter, No. 5
The figure is a system diagram showing an example of a conventional filter device, and FIG. 6 is a sectional view of a gas-liquid separation and backflow prevention device in the same filter device. DESCRIPTION OF SYMBOLS 1... Fuel tank, 2... Supply passage, 4... Injection pump, 7A... Warming fuel passage, 15... Fuel filter,
16... Gas-liquid separation and backflow prevention device, 21... Supply port,
22...Discharge port, 23...Float chamber, 23a...Vacancy, 24...Cover, 25...Liquid level responsive member (float), 26...Backflow prevention means (check valve), 2
7...Fuel discharge port, 28...Inlet port, 29...Discharge port,
30...Fuel passage, 33...Temperature-sensitive valve device.

Claims (1)

[Claims] 1 A fuel filter 15 is installed in the supply passage 2 for supplying fuel to the injection pump 4, and a top cover 20 of the fuel filter 15 is connected to a fuel supply port 21 led from the fuel tank 1 and the injection pump 4. In the fuel filter device for a diesel engine, the upper cover 20 is provided with a space, and the float chamber is formed by the space and a cover 24 disposed and attached above the space. A liquid level responsive member 25 is housed in 23,
At the top of the cover 24, there is a fuel discharge port 27 that communicates with the fuel tank 1 via a backflow prevention means 26, and a heated fuel that guides a portion of the fuel overflowing from the injection pump 4, injection nozzle 5, etc. to the fuel filter 15. A fuel inlet port 28 connected to the passage 7A is provided, a discharge port 29 for the fuel in the float chamber 23 is provided at the bottom of the float chamber 23 and is opened and closed by the liquid level responsive member 25, and the supply port 21
A temperature-sensitive valve device 33 is formed in the upper cover 20 to detect that the temperature of the fuel flowing through the float chamber 23 is below a predetermined value and to flow the fuel flowing out from the fuel discharge port 29 in the float chamber 23 to the supply port 21. Fuel filter device for diesel engines.