JPH07103832B2 - Diesel engine fuel system circulation system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fuel system circulation device for a diesel engine.

[Prior Art] In general, a fuel system of a diesel engine includes components such as a fuel tank 1, a water separator 2, a feed pump 3, a fuel filter 4, an injection pump 5, and an injection nozzle 6 as shown in FIG. It is configured.

During operation after the diesel engine is started, the fuel in the fuel tank 1 is sucked up by the feed pump 3, the water content in the fuel is removed by the water separator 2, and a plunger and spring (not shown) inside the feed pump 3 are arranged. After passing through the gallery chamber 3a and passing through the fuel filter 4, it is sent to the injection pump 5 and is pressure-regulated through the injection pipe 7 by the injection nozzle 6 attached to the cylinder head (not shown) and injected into the combustion chamber. .

Further, the injection pump 5 is provided with an overflow valve 8 for adjusting the pressure of the fuel supplied to the injection pump 5 to a required value. When the pressure of the fuel exceeds the required value, the overflow valve 8 is activated. The fuel is opened and returned to the fuel tank 1 through the overflow pipe 9.

In the figure, 10 is a leakage pipe for returning the fuel that lubricates the nozzle needle of the injection nozzle 6 to the fuel tank 1, 11 is an air vent plug of the fuel filter 4, and 12 is a priming pump provided in the feed pump 3. Shows.

[Problems to be Solved by the Invention] However, in the diesel engine equipped with the fuel system as described above, if a vehicle equipped with the diesel engine is left for a long time at a low temperature in winter, each pipe in the fuel system And the like, the viscosity of the fuel is increased, the wax content in the fuel is separated, and the air is mixed with the mixed air, so that the fuel atomization by the injection nozzle 6 at the start is deteriorated and the engine is started. There were problems such as causing defects, increasing black or white smoke in exhaust gas, and generating odor.

In view of such circumstances, the present invention aims to provide a fuel system circulation device for a diesel engine capable of improving engine startability at low temperatures and reducing black smoke, white smoke, odor, etc. in exhaust gas. Is.

[Means for Solving the Problems] The present invention provides a check valve that allows only the flow of fuel toward the feed pump in the line on the suction side of the feed pump in the fuel system of a diesel engine, and the line is also provided. Forming a bypass line connecting the upstream and downstream positions of the check valve, providing a pump in the bypass line, and switching the diesel engine start switch to the pre-heat side and the start side in the circuit that supplies power to the pump. It is characterized in that an a contact of a relay excited by an operation is provided, and a branch line that branches from a line on the suction side of a feed pump in a fuel system of a diesel engine and leads to a gallery chamber of the feed pump. And a check valve that allows only the flow of fuel toward the gallery chamber is provided in the branch line, and A pump is installed upstream of the check valve in the branch line, and the circuit that supplies power to the pump is connected to the pre-switch of the diesel engine start switch.
It is characterized in that an a contact of a relay is provided which is excited by the switching operation to the heat side and the start side.

[Operation] Therefore, when starting the engine, the start switch is first switched to the pre-heat side to preheat the engine, and then the start switch is switched to the start side to start the engine. When closed, the pump is driven, the cold fuel in each pipe is forcibly pumped to the fuel tank via the feed pump, and the fuel in the fuel tank, which has almost no effect at low temperature, is circulated. The fuel atomization at the time becomes good.

When the engine is started, the pump is stopped, the feed pump is operated, and in the former case, that is, with the pump provided in the bypass line, the fuel is not reversely diverted from the line on the suction side of the feed pump to the bypass line. It is sucked into the feed pump through the valve and pumped to the downstream side,
In the latter case, that is, in the case where a pump is provided in the branch line,
The fuel sucked into the gallery chamber inside the feed pump from the suction side line of the feed pump is pumped to the downstream side by the check valve without flowing back to the branch line.

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

FIG. 1 and FIG. 2 show an embodiment of the present invention and are
The parts denoted by the same reference numerals as those in the figure represent the same things.

As shown in FIG. 1, the line on the suction side of the feed pump 3
A check valve 14 that allows only the flow of fuel from the water separator 2 side to the feed pump 3 side is provided in 13 and a bypass line 15 that connects the upstream and downstream positions of the check valve 14 in the line 13 is formed. A pump 16 such as an electromagnetic pump, an electric pump, or a colloidal pump is provided in the bypass line 15.

The pump 16 includes a coil 22 of a relay 21 as shown in FIG.
By the operation of the a-contact 23 which is opened / closed by the excitation of, the current from a battery (not shown) flows and is driven.

The coil 22 of the relay 21 is excited by the switching operation of the diesel engine starting switch 24 to the pre-heat side or the start side.

With the above-described configuration, when the engine is started, the start switch 24 is first switched to the pre-heat side to preheat the engine, and then the start switch 24 is switched to the start side to start the engine. The coil 22 of 21 is excited, the a-contact 23 is closed, and the pump 16 is driven.

When the pump 16 is driven, the fuel remaining in each pipe of the fuel system is pressure-fed by a route that bypasses the line 13 to the bypass line 15 and flows into the gallery chamber 3a inside the feed pump 3, and further the fuel filter. Flow into the injection pump 5 via 4, the overflow valve 8 is opened by the discharge pressure of the pump 16, fuel is returned from the overflow pipe 9 to the fuel tank 1, and
The fuel that is stored in the fuel tank 1 and has almost no influence at the time of low temperature, that is, the change in the viscosity and the separation of the wax component is circulated, and the air is removed from the fuel system at the same time.

Therefore, even when the temperature is low, atomization of the fuel injected from the injection nozzle 6 into the combustion chamber at the time of engine start by the start switch 24 becomes good, engine start failure does not occur, and black smoke or white in exhaust gas is generated. It also prevents smoke and odors from increasing.

After the engine is started, the start switch 24 is in a neutral state as shown in FIG. 2, so the a contact 23 of the relay 21 is opened and the pump 16 is stopped, and the feed pump 3 sucks up fuel from the fuel tank 1. It passes through the water separator 2 and the line 13 to the bypass line 15 without passing through the check valve, passes through the gallery chamber 3a inside the feed pump 3, is sent to the injection pump 5 through the fuel filter 4, and is injected from the injection nozzle 6. It is injected into the combustion chamber.

Further, FIG. 3 shows a modification of the fuel system shown in FIG. 1, in which a plunger (not shown) incorporated in the feed pump 3 is directly attached to the lid 20 which also serves as a spring seat. The outlet side of the valve 14 is connected, and a branch line 19 leading to the inlet side of the check valve 14 is connected to the suction side joint portion 18 of the feed pump 3 to which the line 13 is connected. , An electromagnetic pump for electric-pressure-feeding fuel from the suction side joint portion 18 side to the check valve 14 side, an electric pump,
A pump 16 such as a trochoid pump is provided.

In the pump 16, as in the case of the above-described embodiment, as shown in FIG. 2, a current from a battery (not shown) flows due to the operation of the a contact 23 which is opened and closed by exciting the coil 22 of the relay 21. The coil 22 of the relay 21 is energized by switching the starting switch 24 of the diesel engine to the pre-heat side or the start side.

Even in the case of the above modification, when the engine is started,
The pump 16 is driven in conjunction with the switching of the start switch 24 to the pre-heat side and the switching to the start side, and the fuel remaining in each pipe of the fuel system flows from the line 13 to the branch line 19 and is non-returned. It is pressure-fed in a path that flows from the port 17 through the valve 14 into the gallery chamber 3a inside the feed pump 3, further flows into the injection pump 5 through the fuel filter 4, and the overflow valve 8 is opened by the discharge pressure of the pump 16. , The fuel is returned from the overflow pipe 9 to the fuel tank 1, and the fuel stored in the fuel tank 1 is circulated with the effect of low temperature, that is, the change of viscosity and the separation of wax component are hardly circulated, and the air is also removed from the fuel system. To be removed.

Therefore, even at low temperatures, atomization of the fuel injected from the injection nozzle 6 into the combustion chamber at the time of engine start by the start switch 24 does not deteriorate, engine startability becomes good, and black smoke in exhaust gas, White smoke and odor are also reduced.

After the engine is started, the pump 16 is stopped, and the fuel sucked up from the fuel tank 1 to the feed pump 3 via the water separator 2 and the line 13 does not flow back to the branch line 19 due to the action of the check valve 14, and the feed pump 3 Three
After passing through the gallery chamber 3a inside, the fuel filter 4,
It is injected into the combustion chamber from the injection nozzle 6 via the injection pump 5.

It should be noted that the fuel system circulation device for the diesel engine of the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made without departing from the scope of the present invention.

[Effects of the Invention] As described above, according to the fuel system circulation device for a diesel engine of the present invention, it is possible to improve the startability of the engine at low temperatures, and at the same time, the black smoke in the exhaust gas,
An excellent effect that white smoke, odor, etc. can be reduced can be obtained.

[Brief description of drawings]

FIG. 1 is a system diagram of one embodiment of the present invention, and FIG.
3 is an explanatory diagram of an electric circuit of the pump shown in FIG. 3 (and FIG. 3).
FIG. 1 is a system explanatory diagram showing a modified example of the fuel system shown in FIG.
FIG. 4 is a system explanatory view showing a conventional example. 1 is a fuel tank, 2 is a water separator, 3 is a feed pump, 3a is a gallery chamber, 4 is a fuel filter, 5 is an injection pump, 6 is an injection nozzle, 8 is an overflow valve, 13 is a line, 14
Is a check valve, 15 is a bypass line, 16 is a pump, 18 is a suction side joint portion, 19 is a branch line, 20 is a lid, 21 is a relay, 22 is a coil, 23 is an a contact, and 24 is a start switch.

Claims (2)

[Claims] 1. A check valve for allowing only a flow of fuel to the feed pump is provided in a line on a suction side of a feed pump in a fuel system of a diesel engine, and a check valve upstream and downstream positions of the line. A bypass line connecting the pumps, a pump is provided in the bypass line, and a circuit for supplying electric power to the pump is provided with a relay that is excited by the switching operation of the diesel engine start switch to the pre-heat side and the start side. A diesel engine fuel system circulation device having an a-contact. 2. A branch line that branches from a line on the suction side of a feed pump in a fuel system of a diesel engine and communicates with a gallery chamber of the feed pump, and in the branch line, only the flow of fuel toward the gallery chamber is formed. In addition to providing a check valve for allowing the above, a pump is provided at a position upstream of the check valve in the branch line, and a circuit for supplying electric power to the pump is switched to a preheat side or a start side of a start switch of a diesel engine. A fuel system circulation device for a diesel engine, which is provided with an a contact of a relay excited by an operation.