JPH0122935Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application The present invention relates to an air bleed device for a diesel engine, particularly a diesel engine of a constant pressure starting type, in which a fuel pump and a filter are arranged in that order.

(b) Prior art Conventionally, a constant pressure startup type fuel pump and a filter are inserted in that order into a pipe line between a fuel tank and an injection pump, and the air bleed part of the injection pump is connected to the fuel tank through an air bleed pipe. Connected diesel engines are already known.

(c) Problems to be solved by the invention In the above-mentioned known diesel engine, excess fuel from the injection pump continued to flow back into the fuel tank even after air was bled out, so the oil pressure in the pipe leading from the fuel pump to the injection pump was As a result, the fuel pump pumps more fuel than the diesel engine consumes, which increases power consumption and causes the filter to become clogged earlier.In machines that are used for long periods of time, the frequency of filter clogging increases. It was expensive and it was not possible to use an air bleed circuit.

In addition, because the injection pump's air bleed pipe and the injection nozzle's surplus fuel pipe were connected to the fuel tank using separate pipes, the pipeline became complicated, making piping work difficult and costly in a narrow space. I got high.

(d) Means for solving the problem The present invention involves inserting a constant-pressure starting type fuel pump and a filter in that order into a pipe line that sends fuel from a fuel tank to an injection pump, and removing the air from the air bleed part of the injection pump. Connect to the fuel tank with an air bleed pipe,
In a diesel engine in which a discharge port of an injection pump is connected to an injection nozzle, a control valve that is closed by fuel from the injection pump to suppress the outflow of fuel is interposed in the air vent pipe, and the control valve is connected to the air vent pipe. By merging the surplus fuel return pipes of the injection nozzles, the internal pressure is quickly raised in the conduit on the discharge side of the fuel pump after air is removed, and the conduit is simplified, thereby solving the above-mentioned problems.

(d) Function The fuel pump pumps the fuel in the fuel tank to the injection pump through the filter, and immediately after starting, the air in the pipe leading from the strainer and the fuel tank to the injection pump passes through the air bleed pipe. The excess fuel from the injection pump, which is rapidly drained into the fuel tank, is drained into the bleed pipe, which closes the control valve, so that the pressure in the line leading from the fuel tank to the injection pump quickly increases.

Surplus fuel from the injection nozzle passes through the surplus fuel return pipe, joins the air vent pipe at the control valve, and is returned to the fuel tank.

(F) Example The example shown in the drawings will be explained below.
1 is a diesel engine equipped with an injection pump 2 and injection nozzles 3, 3, a fuel tank 4 is connected to the suction port of the injection pump 2 through a pipe 5, and a discharge port of the injection pump 2 is connected to the injection nozzle 3. , 3 through pipes 6, 6.

Further, a fuel pump 7 consisting of a diaphragm type electromagnetic pump and a strainer 8 are inserted in that order into the pipe line 5, and the fuel pump 7 is driven by electric power from a battery 9, and the oil pressure on the discharge side reaches the lower limit pressure. When the pressure goes down, the switch turns on and starts, and when the pressure rises to the upper limit, the switch turns off and stops, and the air bleed part 8a of the strainer 8 communicates with the fuel tank 4 through a return pipe 10.

Further, the air bleed part of the fuel injection pump 2 is connected to the fuel tank 4 through an air bleed pipe 11, and the surplus fuel generated in the injection nozzles 3, 3 is returned to the middle part of the air bleed pipe 11. They are connected by a pipe 12.

A control valve 13 is interposed at a portion of the air vent pipe 11 where the surplus fuel return pipe 12 joins, and the control valve 13 has a cylindrical shape as shown in FIG. Valve seat 1 consisting of a surface
3a, and a spherical valve 14, which is lighter than fuel such as synthetic resin, is inserted inside.

Next, to explain the operation, the fuel pump 7
pressurizes the fuel taken in from the fuel tank 4, the pressurized fuel is leaked through a strainer 8 and then sent to the injection pump 2, which pumps the fuel to the injection nozzles 3, 3.

Immediately after starting, the air in the pipe 5 and the injection pump 2 rapidly flows out from the air vent pipe 11 and is discharged into the fuel tank 4. As a result, the spherical valve 14 floats up along with the liquid level, and finally comes into pressure contact with the valve seat 13a, closing the control valve 13 as shown in FIG. The sent fuel is returned to the fuel tank 4 through the return pipe 10, and the oil pressure increases due to the line resistance of the return pipe 10, and when the upper limit pressure is reached, the fuel pump 7 is stopped.

Also, after the control valve 13 is closed, the injection nozzles 3, 3
The surplus fuel discharged from the valve seat 13a is drained from the thin groove 1 of the valve seat 13a
3b to the fuel tank 4.

FIG. 4 shows another embodiment in which the surplus fuel return pipe 12 is connected to the valve seat 13a of the control valve 13.
Since the valve seat 13a does not have the groove 13b, immediately after the air is discharged, the air is
As shown in the figure, the surplus fuel flows into the valve chamber of the control valve 13 and joins the surplus fuel from the injection pump.
After the control valve 13 is closed, the fuel does not flow into the valve chamber but flows back into the fuel tank 4 as shown in b.

That is, since the control valve 13 closes at the same time as the air removal is completed, the internal pressure of the conduit 5 rises more quickly than in the previously described embodiment, resulting in unnecessary power consumption and strainer 8.
can prevent clogging.

(g) Effects of the invention As described above, the present invention inserts a constant-pressure starting type fuel pump 7 and a filter in that order into the pipe line 5 that sends fuel from the fuel tank 4 to the injection pump 2. In a diesel engine in which an air bleed part is connected to a fuel tank 4 through an air bleed pipe, and a discharge port of an injection pump 2 is connected to an injection nozzle 3, the air bleed pipe is closed by the fuel from the injection pump 2. A control valve 13 for suppressing the outflow of fuel is provided, and the surplus fuel return pipe 12 of the injection nozzle 3 is joined to the control valve 13, so that after air is removed, the discharge side of the constant pressure starting type fuel pump 7 is connected to the control valve 13. The internal pressure of the pipe 5 quickly rises and the fuel pump 7 stops, reducing power consumption and reducing the amount of fuel passing through the strainer to prevent its clogging. The engine can now be used for long periods of time.

In addition, since the surplus fuel return pipe 12 from the injection nozzle 3 is made to join the air return pipe 11 by the control valve 13, the control valve 13 can be used as a joint for joining, and a special joint is created. There is no need to provide one, and there is no need to extend the surplus fuel return pipe 12 to the fuel tank 4, so the piping can be shortened, and as a result, piping can be easily installed in a narrow space and costs can be reduced. .

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention,
Fig. 1 is a fuel piping diagram of a diesel engine, Fig. 2 a and b are cross-sectional views of the control valve, c is a cross-sectional view taken along line A-A in a, and Fig. 3 a and b are other embodiments of the control valve. FIG. 1... Diesel engine, 2... Injection pump,
3...Injection nozzle, 4...Fuel tank, 5...Pipe line, 7...Fuel pump, 8...Strainer, 1
1... Air return pipe, 12... Surplus fuel return pipe, 13... Control valve, 14... Spherical valve.

Claims (1)

[Scope of utility model registration request] A constant pressure startup type fuel pump 7 and a filter are inserted in that order into a pipe line 5 that sends fuel from the fuel tank 4 to the injection pump 2, and the air bleed part of the injection pump 2 is connected to the fuel tank 4 with an air bleed pipe. In a diesel engine in which a discharge port of an injection pump 2 is connected to an injection nozzle 3, a control valve 13 is interposed in the air vent pipe to close the air vent pipe by the fuel from the injection pump 2 to suppress the outflow of fuel. ,
An air bleed device for a diesel engine, characterized in that a surplus fuel return pipe 12 of the injection nozzle 3 is joined to the control valve 13.