JPH0128297Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a circulating fuel supply system for low quality oil engines, mainly diesel engines.

(Prior Art and its Problems) Generally, in diesel engines that use low-quality fuel oil, residual fuel oil in the fuel injection pump cools and solidifies during the engine stop period. Therefore, when the engine is restarted, the hardened residual fuel oil becomes an obstacle, making it impossible to restart the engine smoothly.

Currently, in order to prevent the above-mentioned problems, a system has been developed in which a main fuel return pipe is provided separately from the main fuel pipe, and this main fuel return pipe is connected to the return outlet of the fuel injection pump. That is, a fuel supply system has been developed in which, when the engine is restarted, the residual fuel oil in the injection pump is flushed out into the return main pipe with fresh high-temperature fuel oil. However, since the fuel (supply) main pipe and the fuel return main pipe are provided separately, a large installation space is required. Furthermore, since mounting members such as U-bolts are required for each main pipe, the mounting work is also time-consuming. Moreover, it was necessary to wrap asbestos for insulation around each of the two main pipes, which made the installation work even more time-consuming and the installation space even larger.

The applicant of this application previously developed and applied for a device in which the fuel return side main pipe is inserted into the fuel main pipe as a device to eliminate the above-mentioned problems (Japanese Patent Application No. 1983-
4386, that is, Japanese Patent Application Laid-open No. 58-122357).

Although the above application has not yet been published at the time of filing, by inserting and arranging a small-diameter fuel return side main pipe into the fuel main pipe for supplying low-quality fuel oil, two
The structure has been designed with multiple pipes to save on the work of wrapping asbestos for insulation around each main pipe, and to make the space for installing the main pipes more compact.

However, since the fuel return main pipe located inside the main fuel pipe is fixed to the main pipe by welding,
It is impossible to disassemble both main pipes. This is the reason why the main pipe cannot be cleaned thoroughly. That is, as the engine is used, residues (insoluble components) in the form of sludge or grease accumulate in the main pipe, but it is extremely difficult to sufficiently remove such residues because the double pipe structure cannot be disassembled.

(Purpose of the invention) The present invention is a further improvement of the device of the above-mentioned application, and the fuel return main pipe can be freely attached to and detached from the fuel main pipe by using the fuel return part and threaded joint pipe of the fuel return main pipe. By fixing it to the surface, it is possible to simplify the manufacture of the device and also to make cleaning and inspection of the device easy. The present invention will be explained below based on the drawings.

(Example) In Figure 1, which is a fuel piping system diagram, 1 is 6.
This is a top view of the cylinder diesel engine body, and each cylinder is provided with a fuel injection pump 2. 3 is a fuel tank equipped with a fuel heater 3'. The lower end outlet of the fuel tank 3 is connected to a fuel heater 7 via a tank 5 and an air separator 6.
The outlet of the fuel heater 7 is connected to a fuel feed pump 9 via a first fuel filter 8. Reference numeral 10 denotes a large-diameter circulating fuel main pipe, which extends substantially parallel to the crankshaft (center line 0). Inside this circulating fuel main pipe 10, a small-diameter fuel return main pipe 12 is disposed. Fuel main pipe 10
The left end in FIG. 1 is connected to the discharge part of the feed pump 9 via a second fuel filter 13 and a pressure regulating valve 14, and the right end in FIG. and is connected to the fuel tank 3. For example, six fuel supply parts 17 are formed at intervals in the pipe length direction in the middle of the main fuel pipe 10, and these fuel supply parts 17 are connected to the inlet part 18 of each fuel injection pump 2, while the return side Fuel return portions 19 are formed in the main pipe 12 at intervals in the pipe length direction, and the return portions 19 are connected to a fuel return outlet portion 20 of the fuel injection pump 2 . A discharge portion 22 of the fuel injection pump 2 is connected to a fuel injection nozzle 23 .

Next, a detailed structure of both the main pipes 10 and 12 and a structure for detachably attaching the return side main pipe 12 to the fuel main pipe 10 will be explained. In FIG. 2, by arranging the return side main pipe 12 extending in the length direction of the fuel main pipe 10 within the fuel main pipe 10, the fuel main pipe 10
The interior is divided into two passages. That is, it is divided into a generally annular fuel supply passage 25 formed between the inner peripheral surface of the main fuel pipe 10 and the outer peripheral surface of the return main pipe 12, and a fuel return passage 26 within the return main pipe 12. In other words, both the passages 25 and 26 extend in the pipe length direction, and substantially the entire outer peripheral surface of the return side main pipe 12 is surrounded by the supply passage 25.

First and second flanges 31 and 34 are welded to both lengthwise ends of the main fuel pipe 10, respectively. The first flange 31 is a flange 32 of the fuel supply pipe 32
a by bolts 37, whereby the supply passage 25 communicates with the feed pump 9 (FIG. 1) via the fuel supply pipe 32. The second flange 34 is attached to the flange 38 of the return oil pipe 30 with bolts 39.
However, the outlet flange 40 of the return side main pipe 12 is clamped between the flanges 34 and 38 via a packing 41. Thereby, the return passage 26 communicates with the fuel tank 3 via the return oil pipe 30 and the pressure regulating valve 15 (FIG. 1), while the supply passage 25
The right end in FIG. 2 is closed by an outlet flange 40. The outlet flange 40 is welded to the return main pipe 12.

A nut cover 33 is welded to the left end of the return side main pipe 12 in FIG. 2, and a plug 35 is screwed to the inner peripheral side of the nut cover 33. The plug 35 has an orifice 3 with a small diameter (for example, 3 mmφ to 5 mmφ).
6 is formed. That is, the return passage 26 and the inside of the fuel supply pipe 32 communicate with each other via the orifice 36.

The fuel supply section 17 is formed of a pipe, and is welded downward to the through hole 44 at the lower end of the main fuel pipe 10. The fuel return section 19 is formed of a pipe having a slightly smaller diameter or the same diameter as the pipe of the fuel supply section 17, and is welded downward to the through hole 45 at the lower end of the return side main pipe 12. A female threaded portion 46 is formed on the inner periphery of the fuel return portion 19 .

The fuel return portion 19 is detachably attached to the annular mounting seat 47 of the main fuel pipe 10 by means of a threaded joint pipe (union joint) 48. That is, the joint pipe 4
8 is inserted into the mounting seat 47 from the outside of the main fuel pipe 10 and is screwed onto the fuel return portion 19, and the collar portion 48a of the joint pipe 48 is pressed against the surface of the mounting seat 47 via the packing 50. Thereby, the fuel return portion 19 is fixed to the back surface of the mounting seat 47. Note that the mounting seat 47 is welded to the main fuel pipe 10.

An oil pipe 52 is connected to the lower end portion of the joint pipe 48 by a cap nut 51, and the oil pipe 52 is connected to the fuel return outlet portion 20 of the fuel injection pump 2 (FIG. 1). That is, the fuel return section 19 is connected to the joint pipe 48.
It communicates with the fuel return outlet section 20 of the fuel injection pump 2 via an oil pipe 52 .

As the return side main pipe 12, a pipe having a thinner wall than the fuel main pipe 10 is used. That is, the return side main pipe 12 is housed within the fuel main pipe 10, and the return side main pipe 12 is housed within the fuel main pipe 10.
0, a thin-walled pipe is sufficient. Further, the flow cross-sectional area of the return passage 26, that is, the circular cross-sectional area in FIG. 3, is smaller than the flow cross-sectional area of the supply passage 25, that is, the circular cross-sectional area in FIG. Also, fuel main pipe 1
Asbestos is wrapped around the outer circumference of 0. Note that 57 in FIGS. 2 and 3 is an air vent, and 58 is a plug screwed into the air vent 57.

The fuel main pipe 10, which is provided with the return side main pipe 12 in a detachable manner as described above, has a plurality of supports 54 fixed to the cylinder block 53 as shown in FIG.
is fixed by a plurality of U bolts 55.
In addition, in FIG. 4, 56 is a pump mounting base.

For cleaning and inspection inside the main pipes 10 and 12,
When removing the return side main pipe 12 from the fuel main pipe 10, for example, remove the U bolt 55 shown in FIG. 30 from the flanges 32a and 38. Thereafter, each joint pipe 48 is removed from each fuel return section 19, the return side main pipe 12 is shifted upward in FIG. 2, and the fuel main pipe 10 is pulled out to the right in FIG. 2.

When assembling, the steps can be performed in the reverse order of disassembly.

Next, the effect will be explained. When restarting the engine, first turn off the feed pump 9 (Fig. 1).
Then, the fuel heater 7 and the like are operated to send high-temperature fuel oil from the fuel supply pipe 32 to the supply passage 25. The high temperature fuel oil sent into the supply passage 25 is
While passing through the supply passage 25, the cooled fuel oil in the return passage 26 is warmed from the entire circumference of the return side main pipe 12. A portion of the hot fuel oil from the fuel supply pipe 32 is also injected into the return passage 26 through an orifice 36 (FIG. 2) to directly warm the cooled and solidified residual fuel oil in the return passage 26. The high temperature fuel oil sent into the fuel injection pump 2 from the supply passage 25 is
The cooled and hardened residual fuel oil in the injection pump 2 is warmed up, flushed into the return passage 26, and returned to the fuel tank 3. By circulating the fuel oil in this manner, the engine is warmed up, and the engine is started when the fuel oil is flowing smoothly. Furthermore, in order to completely eliminate the warm-up time, a method is adopted in which the fuel feed pump 9 is always operated even when the engine is stopped to circulate heated fuel.

(Effects of the invention) As explained above, the present invention: (a) forms the fuel return part mounting seat 47 and the fuel supply part 17 on the large diameter fuel main pipe 10 connected to the fuel feed pump 9; A fuel return part 19 having a threaded part 46 is integrally formed in the small diameter fuel return main pipe 12 connected to the tank 3, and (c) the fuel return main pipe 12 is inserted into the fuel main pipe 10, and a threaded joint Return part 19 by pipe 48
(d) Connect the fuel inlet part 18 of the fuel injection pump 2 to the fuel supply part 17, and connect the fuel return outlet part 20 of the fuel injection pump 2 to the mounting seat 47 via the threaded joint pipe 48. It is characterized in that it is connected to the fuel return section 19.
Therefore, there are the following advantages.

That is, since the fuel return side main pipe 12 disposed inside the fuel main pipe 10 is removably fixed to the fuel main pipe via the threaded joint pipe 48 or the like, the return side main pipe 12 can be removed from the fuel main pipe 10 and each main pipe 10 , 12 can be cleaned and inspected independently, and residues accumulated due to use can be easily removed. That is, even though the double pipe structure is adopted, cleaning and inspection can be easily performed, and maintenance is good.

Particularly when the return portion 17 is welded to the return side main pipe 12, welding gas may accumulate in the fuel main pipe 10, but such welding gas can also be easily removed.

Furthermore, similar to the earlier patent application of Utility Model Application No. 57-4386 which adopted the double pipe structure mentioned above, there are also the following advantages.

(1) Since the small-diameter fuel return side main pipe 12 is arranged inside the large-diameter main fuel pipe 10, there is no flow from the fuel feed pump 9 into the fuel main pipe 10 (the annular supply passage 2).
5) The interior of the return side main pipe 12 is heated extremely efficiently from its entire circumference by the high-temperature fuel oil sent to step 5), and the warm-up time of the engine is significantly shortened. Further, since there is no need to wrap asbestos for heat insulation around the return side main pipe 12, the installation work does not take much time.

(2) Since the return side main pipe 12 is built into the fuel main pipe 10, the installation space can be small even though two main pipes 10 and 12 are actually used. Further, only the number of mounting members such as the U-bolts 55 required for one main pipe can be used, further reducing the labor required for the mounting work.

(5) Since the return side main pipe 12 is fixed to the fuel main pipe 10 using the return oil joint pipe 48, there is no need to provide special members (mounting bolts, etc.) for fixing the return side main pipe. That is, the number of parts is small and it is economical.

In addition, in the present invention, a thread is formed in the return part 19, a female thread part is formed in the threaded joint pipe 48,
The joint pipe 48 may be screwed into the return portion 19.

[Brief explanation of the drawing]

Fig. 1 is a fuel piping system diagram of the fuel supply device according to the present invention, Fig. 2 is an enlarged vertical cross-sectional view of the main parts, Fig. 3 is a cross-sectional view of Fig. 2, and Fig. 4 shows the installation state of the main fuel pipe. 2 is a cross-sectional view corresponding to FIG. 2; FIG. 2...Fuel injection pump, 3...Fuel tank, 9
... Fuel feed pump, 10 ... Fuel main pipe, 1
2...Fuel return side main pipe, 17...Fuel supply section, 1
8...Fuel inlet section, 19...Fuel return section, 20...
...Fuel return outlet part, 46...Threaded part, 47...
Return part mounting seat, 48...Threaded joint pipe.

Claims (1)

[Scope of utility model registration request] A fuel return part mounting seat 47 and a fuel supply part 17 are formed in a large diameter fuel main pipe 10 connected to the fuel feed pump 9, and a threaded part 46 is formed in a small diameter fuel return main pipe 12 connected to the fuel tank 3. The return part 19 is integrally formed, and the fuel return side main pipe 12 is inserted into the fuel main pipe 10, and the return part 19 is detachably fixed to the mounting seat 47 by the threaded joint pipe 48, so that the fuel of the fuel injection pump 2 The inlet part 18 is connected to the fuel supply part 17 of the main fuel pipe 10, and the fuel return outlet part 20 of the fuel injection pump 2 is connected to the threaded joint pipe 4.
8. A circulating fuel supply system for a low-quality oil engine, characterized in that it is connected to a fuel return section 19 of a return side main pipe 12 via a fuel pump 8.