JPH08121269A - Fuel cooling device - Google Patents

Abstract

PURPOSE: To efficiently cool fuel by means of a small device and to prevent dispersion of fuel in the case of breakage of a cooler or a piping. CONSTITUTION: A fuel tank 4 for supplying fuel to a motor 1 is provided with a fuel supply pipe 6 through which fuel from the fuel tank 4 is fed to the motor 1 by means of a fuel pump 5, while a recirculation pipe 7, which is provided with a cooler 8, for recirculation from the motor 1 to the fuel tank 4 is arranged, and the cooler 8 is arranged at the predetermined interval to an intake part 2b in the front position of an intake filter 2a in an intake path 2, so that the cooler 8 can be cooled by means of intake during operation of the motor 1. In this way, increase in temperature of fuel is suppressed, and the fuel is sucked into the cooler 8 even when the cooler 8 or the vicinity of its piping joint part is damaged and leakage of fuel occurs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cooling device for cooling a fuel supplied to a prime mover such as a construction machine.

[0002]

2. Description of the Related Art Fuel for operating a prime mover is supplied from a fuel tank to a carburetor through a fuel supply pipe. Excess fuel in the carburetor is returned to the fuel tank. I have to. in this way,
The fuel circulates between the fuel tank and the prime mover, during which the temperature of the fuel rises due to the heat of combustion. And
When the fuel reaches a high temperature above a certain level, there is a problem that a so-called vapor lock or forming phenomenon is caused. For this reason, for example, in Japanese Utility Model Laid-Open No. 61-73058, there has been known a structure in which a cooler is provided in a return path from a prime mover of this fuel and the fuel is cooled by the cooler.

[0003]

By the way, in the above-mentioned prior art, although the specific structure of the cooler is not shown, the cooler is formed by a pipe or a container provided with cooling fins. It is common to However, since it is not possible to perform efficient cooling simply by providing cooling fins, it is necessary to use a fan to send cooling air to this cooler. For this reason, the entire fuel cooling system becomes large, and in the event of an accident such as pipe or cooler damage, the entire chamber in which the prime mover is installed may be filled with atomized fuel. is there.

The present invention has been made in view of the above points, and an object of the present invention is to provide a small device configuration.
The purpose is to efficiently cool the fuel and prevent the fuel from scattering even if the cooler or the pipe is damaged.

[0005]

In order to achieve the above object, the present invention provides a prime mover, a fuel tank for supplying fuel to the prime mover, fuel from the fuel tank to the prime mover, and a surplus from the prime mover. And a fuel circulation pipe for circulating the fuel in the fuel tank,
A characteristic is that a cooler is provided in the middle of the fuel circulation pipe and the cooler is arranged at a position facing the intake port of the prime mover.

[0006]

By arranging the cooler provided in the fuel circulation pipe at the intake port of the prime mover, the air flow during intake from this intake port acts as cooling air for the cooler.
Therefore, it is not necessary to provide a separate fan, and the structure of the cooling device can be simplified and downsized. Also, since the air flow that has cooled this cooler is sucked into the prime mover, even if the cooler and the pipes connected to this cooler are damaged and fuel leaks, this fuel is sucked into the prime mover. Therefore, there is no particular danger.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. First, FIGS. 1 to 3 show a first embodiment of the present invention. In FIG. 1, 1 is a prime mover, and this prime mover 1 is provided with an intake passage 2 and an exhaust passage 3. The intake passage 2 is provided with an intake filter 2a, and the exhaust passage 3 is provided with an exhaust muffler 3a. A fuel tank 4 is provided to supply fuel to the prime mover 1, and fuel from the fuel tank 4 is provided with a fuel supply pipe 6 to the prime mover 1 by a fuel pump 5.
Further, a fuel recirculation pipe 7 is provided from the prime mover 1 to the fuel tank 6. Therefore, the fuel supply pipe 6 and the fuel return pipe 7 form a fuel circulation pipe.

Further, in the figure, reference numeral 8 denotes a cooler, which is arranged in the middle of the fuel recirculation pipe 7 and has a cooling fin as is well known. It is arranged at a predetermined interval in the suction portion 2b at the front position of the intake filter 2a in the intake passage 2.

The present embodiment is constructed as described above, and when the prime mover 1 is operated, the fuel pump 5 is activated and the fuel is supplied from the fuel tank 4 to the prime mover 1 through the fuel supply pipe 6. The supplied fuel is vaporized in the vaporizer (not shown) of the prime mover 1 and injected from the fuel injection valve. Then, the excess fuel from the vaporizer is used as the fuel return pipe 7
It is returned to the fuel tank 4 via. When this surplus fuel is returned to the fuel tank 4, the temperature of the fuel in the fuel tank 4 rises due to the combustion heat. Since the fuel is highly volatile, if the fuel temperature rises too much, as shown in FIG. 2, the shaft output of the prime mover 1 will significantly decrease, and if the fuel temperature becomes extremely high, the fuel will There is a problem such as a so-called forming phenomenon, in which a so-called vapor lock phenomenon occurs, which partially becomes a vapor state and stays in a pipe or the like to hinder the fuel supply, or a large amount of bubbles are generated in the fuel tank 4. It will be.

However, since the fuel recirculation pipe 7 is provided with the cooler 8, the fuel that recirculates from the prime mover 1 is cooled by the cooler 8, so that the rise in the fuel temperature is suppressed. The fuel temperature does not rise to the extent that it affects the operation of the prime mover 1. Moreover, in cooling the fuel using the cooler 8, the flow of air due to the suction by the intake passage 2 in the prime mover 1 is used, so that it is not necessary to provide a fan for supplying cooling air. The overall structure of the cooling device can be simplified and made compact.

By the way, if the cooler 8 is disposed so as to face the suction portion 2b of the intake passage 2 of the prime mover 1, the intake efficiency will decrease. However, the relationship between the intake resistance and the shaft output is as shown in FIG. 3, and even if the intake resistance is increased to some extent, the shaft output is not significantly affected. As compared with the increase in the fuel temperature in FIG. 2, the cooler 8 is disposed so as to face the suction portion 2b to cool the fuel efficiently even if the intake efficiency is slightly reduced. Operating efficiency will be good.

Moreover, almost all the flow of air which comes into contact with the cooler 8 is sucked into the intake passage 2,
Even if the cooler 2 and the connection parts of the fuel supply pipe 6 and the fuel return pipe 7 to the cooler 2 are damaged and the fuel flows out,
The fuel thus flowing does not atomize and scatter, and is sucked into the prime mover 1, so that it is possible to prevent a dangerous situation from occurring.

Here, the cooler 8 may be provided on the fuel supply pipe 7 side as shown in FIG. 4, instead of on the fuel return pipe 6 side as shown in FIG.

By the way, when the cooler is arranged opposite to the suction part of the intake passage, the fuel is always cooled by the cooler when the prime mover 1 is operated. For example, in a cold region, the fuel temperature is low. In some cases, there is a risk that the fuel will be chemically deteriorated due to excessive deterioration. In such a case, as shown in FIG. 5, a path passing through the cooler and a path not passing through the cooler may be provided, and the paths may be switched depending on the fuel temperature.

In FIG. 5, members which are the same as or equivalent to those in FIG. 1 are designated by the same reference numerals, and description thereof will be omitted. In addition, in the embodiment of FIG.
Similarly to the above, the cooler 8 is arranged on the fuel supply pipe 6 side, but it goes without saying that the cooler 8 may be arranged on the fuel return pipe 7 side.

A thermometer 10 for measuring the fuel temperature is installed in the fuel tank 4, and a bypass pipe 11 is provided in the middle of the fuel supply pipe 7 to provide a fuel supply path not through the cooler 8. . Then, a portion of the fuel supply pipe 6 on the upstream side of the disposition position of the cooler 8 and the bypass pipe 11
A switching valve 12 of an electromagnetic switching type is provided between and, and the switching valve 12 is always in a state where the fuel supply pipe 7 is opened and the bypass pipe 11 is closed. When the fuel temperature is equal to or lower than a predetermined temperature, the fuel supply pipe 7 is closed and the bypass pipe 11 is opened based on the signal from the thermometer 10.

With such a configuration, the switching valve 12 is always held in the state shown in the drawing, whereby the fuel supply pipe 7 is opened and the bypass pipe 11 is closed, so that the fuel is supplied from the fuel tank 4. The fuel is cooled by the cooler 8 and held so that the fuel temperature does not rise.
However, when it is detected by the thermometer 10 that the temperature has dropped to such an extent that the fuel may be chemically deteriorated, the switching valve 12 is switched based on the signal from the thermometer 10, Since the path from the fuel supply pipe 6 through the cooler 8 is cut off and the bypass pipe 11 is opened, the fuel is supplied to the prime mover 1 without passing through the cooler 8, and the fuel temperature is abnormally lowered. There is nothing to do.

[0018]

As described above, according to the present invention, which is provided with the fuel circulation pipe, a cooler is provided in the middle of the fuel circulation pipe, and the cooler faces the intake port of the prime mover. Since it is arranged at the position, the fuel can be efficiently cooled with a small device structure, and further, even if the cooler or the pipe is damaged, the fuel does not scatter.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a fuel system incorporating a fuel cooling device showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a fuel temperature and a shaft output of a prime mover.

FIG. 3 is a diagram showing a relationship between intake efficiency and a shaft output of a prime mover.

FIG. 4 is a structural explanatory view of a fuel system incorporating a fuel cooling device showing a second embodiment of the present invention.

FIG. 5 is a structural explanatory view of a fuel system incorporating a fuel cooling device showing a third embodiment of the present invention.

[Explanation of symbols]

 1 prime mover 2 intake passage 3 exhaust passage 4 fuel tank 6 fuel supply pipe 7 fuel return pipe 8 cooler 10 thermometer 11 bypass pipe 12 switching valve

Claims (4)

[Claims] 1. A prime mover, a fuel tank for supplying fuel to the prime mover, and a fuel circulation pipe for feeding fuel from the fuel tank to the prime mover and circulating excess fuel from the prime mover to the fuel tank. In the fuel cooling apparatus, a cooler is provided in the middle of the fuel circulation pipe, and the cooler is arranged at a position facing the intake port of the prime mover. 2. The fuel cooling device according to claim 1, wherein the cooler is arranged on a fuel supply side of the fuel circulation pipe. 3. The fuel cooling device according to claim 1, wherein the cooler is arranged on the fuel circulation side of the fuel circulation pipe. 4. The fuel circulation pipe can be switched between a path passing through the cooler and a path not passing through the cooler, and the path is switched according to the temperature in the fuel tank. It has a structure.
The fuel cooling device according to any one of 1.