JPH02305357A - Fuel system circulation device of diesel engine - Google Patents

Abstract

PURPOSE:To improve starting ability at the time of low temperature by providing a bypass line that is routed around a check valve provided on an intake side of a feed pump, and by placing a pump that is driven at the time of change-over operation of a starting switch to a pre-heat side and to a starting side, in the middle of the line. CONSTITUTION:On a line 13 on the intake side of a feed pump 3 that feeds oil to an injection pump 5 through a filter 4, a check valve 14 that permits only the fuel flow from a water separator 2 side to a feed pump 3 side, is provided. To the line 13, a bypass line 15 is connected, by which upper and lower flowing positions of the check valve 14 are linked together, and in the middle of the line 15, a pump 16 such as electromagnetic pump or electric pump is placed. Electrification of the pump 16 is carried out by means of closing operation of an a-contact 23 that is opened/closed by excitation of a coil 22 of a relay 21, which is excitated by the change-over operation of a starting switch 24 of a diesel engine to a pre-heat side as well as to a starting side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel system circulation device for a diesel engine.

[Prior Art] Generally, the fuel system of a diesel engine includes parts 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 starting the diesel engine, the fuel in the fuel tank 1 is sucked up by the feed pump 3, water in the fuel is removed by the water separator 2, and a plunger or spring (not shown) is placed inside the foot pump 3. After passing through the gear chamber 3a and being filtered by the fuel filter 4), the fuel is sent to the injection pump 5, and is then pressure-regulated in the injection nozzle 6, which is attached to a cylinder head (not shown), via the injection vibrator 7, and then enters the combustion chamber. Injected.

Further, the injection pump 5 is provided with an overflow valve 8 that regulates the pressure of the fuel supplied to the injection pump 5 to a required value, and when the pressure of the fuel exceeds the required value, the overflow valve 8 is closed. It opens and the fuel overflows through the vibe 9 and returns to the fuel tank 1.

In the figure, IO indicates a leakage pipe for returning the fuel that has lubricated the nozzle needle of the injection nozzle 6 to the fuel tank L, 11 indicates an air bleed plug of the fuel filter 4, and 12 indicates a priming pump provided in the feed pump 3. ing.

[Problem to be solved by the invention] However, in a diesel engine equipped with the fuel system as described above, if a car etc. equipped with the diesel engine is left for a long time at low temperatures in winter, the inside of each pipe of the fuel system will be damaged. As the remaining fuel cools down, the viscosity of the fuel increases and is affected by the separation of the wax component in the fuel and mixed air, resulting in poor atomization of the fuel by the injection nozzle 6 during startup, causing the engine to start. There were problems such as defects, an increase in black or white smoke in the exhaust gas, and the generation of odors.

In view of these circumstances, the present invention seeks to provide a fuel system circulation device for a diesel engine that can improve engine startability at low temperatures and reduce black smoke, white smoke, odor, etc. in exhaust gas. It is.

[Means for Solving the Problems] The present invention provides a check valve in the suction side line of the foot pump in the fuel system of a diesel engine that allows only the flow of fuel toward the feed pump, and A bypass line is formed that connects the two downstream positions of the check valve, a pump is provided on the bypass line, and a circuit that supplies power to the pump includes a switch for switching the starting switch of the diesel engine to the pre-heat side and the start side. It is characterized by having an A contact of a relay that is energized by operation, and is also a branch line that branches from a line on the suction side of a feed pump in a diesel engine fuel system and leads to a gear room of the feed pump. a check valve that allows only the flow of fuel toward the gear gallery chamber is provided in the branch line, a pump is provided upstream of the check valve in the branch line, and a circuit supplies power to the pump. , press the diesel engine start switch preφ
It is characterized by providing a relay a contact which is excited by switching operation to the heat side and the star side.

[Function] Therefore, to start the engine, first switch the start switch to the pre-heat side to preheat the engine, then switch the start switch to the start side to start the engine, but during this time, the a contact of the relay is closed and the pump is activated,
The cold fuel in each pipe is forcibly sent to the fuel tank via the feed pump, and the fuel that is almost unaffected by low temperatures inside the fuel tank is circulated, resulting in good fuel atomization at startup. becomes.

When the engine is started, the pump is stopped and the feed pump is activated, and in the case of the former, that is, the pump is installed in the bypass line, the fuel is flowed from the suction side line of the feed pump to the bypass line without being detoured. The fuel is sucked into the feed pump through a valve and sent under pressure to the downstream side.In the case of the latter, that is, the pump is installed in a branch line, the fuel sucked into the gear chamber inside the feed pump from the suction side line of the feed pump is pumped in the opposite direction. The stop valve allows the water to be pumped downstream without flowing back into the branch line.

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

1 and 2 show an embodiment of the present invention, and the fourth
Parts with the same reference numerals as in the figure represent the same parts.

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

As shown in FIG. 2, the pump 16 is driven by the flow of current from a battery (not shown) by the operation of an a contact 23 which is opened and closed by the excitation of 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 and the star 1 side.

Since the configuration is as described above, when starting the engine, the starting switch 24 is first switched to the pre-heat side to preheat the engine, and then the starting switch 24 is switched to the start side to start the engine. 21
The coil 22 is energized, the a contact 23 closes, and the pump 16
is driven.

When the pump 16 is driven, the fuel remaining in each pipe of the fuel system is transferred from the line 13 to the bypass line 15.
The fuel is detoured to the feed pump 3 through a route that flows into the gear chamber 3a inside the feed pump 3, and further flows into the injection pump 5 via the fuel filter 4. The overflow valve 8 is opened by the discharge pressure of the pump 16, and the fuel flows into the overflow pipe. At the same time, the fuel is returned to the fuel tank 1 from the fuel tank 1, and the fuel stored in the fuel tank 1 with almost no effects at low temperatures, such as changes in viscosity or separation of wax components, is circulated, and air is removed from the fuel system at the same time. be exposed.

Therefore, even at low temperatures, the atomization of the fuel injected into the combustion chamber from the injection nozzle 6 when the engine is started by the start switch 24 is good, the engine does not start poorly, and there is no black smoke or white smoke in the exhaust gas. It also prevents an increase in smoke and the generation of odors.

After the engine is started, the start switch 24 is in the neutral state as shown in FIG. It passes through the water separator 2 from the line 13 to the bypass line 15 without taking a detour, passes through the check valve 14, passes through the gear room 3a inside the foot pump 3, is sent to the injection pump 5 via the fuel filter 4, and is sent to the injection nozzle 6. is injected into the combustion chamber.

Moreover, FIG. 3 shows a modification of the fuel system shown in FIG. 1, in which a lid 20 that also serves as a spring seat for a plunger (not shown) built into the feed pump 3 has a
A suction side joint portion 18 of the feed pump 3 to which the outlet side of the check valve 14 is directly connected and to which the line 13 is connected.
A branch line 19 leading to the inlet side of the check valve 14 is connected to the branch line 19, and an electromagnetic pump and an electric pump are installed in the middle of the branch line 19 for pressure-feeding fuel from the suction side joint part 18 side to the check valve 14 side. Pumps 16 such as pumps and trochoid pumps
will be established.

The pump 16, just like in the previous embodiment,
As shown in FIG. 2, a current from a battery (not shown) flows through the operation of the a contact 23, which is opened and closed by the excitation of the coil 22 of the relay 21. The magnet is energized by switching the engine starting switch 24 to the pre-heat side and the start side.

Even in the case of the above modification, when starting the engine,
The pump 16 is driven in conjunction with the switching of the start switch 24 to the pre-heat side and to the start side, and the fuel remaining in each pipe of the fuel system flows from the line 13 through the branch line 19 and is prevented from returning. Port 17 via valve 14
From there, the fuel is fed under pressure through a path that flows into the gear chamber 3a inside the foot pump 3, and further flows into the injection pump 5 through the fuel filter 4. The overflow valve 8 is opened by the discharge pressure of the pump 16, and the fuel flows from the overflow pipe 9. At the same time, the fuel is returned to the fuel tank I, and the fuel stored in the fuel tank 1 and having almost no effects at low temperatures, such as changes in viscosity or separation of wax components, is circulated, and air is also removed from the fuel system.

Therefore, even at low temperatures, the atomization of the fuel injected into the combustion chamber from the injection nozzle 6 when the engine is started by the start switch 24 does not deteriorate, and the engine startability is improved, and black smoke in the exhaust gas is reduced. White smoke, odors, etc. are also reduced.

After the engine is started, the pump 16 is stopped, and the fuel sucked from the fuel tank 1 through the water separator 2 and the line 13 to the feed pump 3 is prevented from flowing back into the branch line 19 by the action of the check valve 14, and the fuel is pumped into the feed pump. The fuel passes through the gear chamber 3a inside the combustion chamber 3, passes through the fuel filter 4 and the injection pump 5, and is injected from the injection nozzle 6 into the combustion chamber.

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

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

[Brief explanation of the drawing]

Fig. 1 is a system explanatory diagram of one embodiment of the present invention, and Fig. 2 is a system diagram of an embodiment of the present invention.
An explanatory diagram of the electric circuit of the pump shown in Fig. 3 (and Fig. 3).
The figure is a system explanatory diagram showing a modification of the fuel system shown in FIG.
FIG. 4 is a system explanatory diagram showing a conventional example. ■ is a fuel tank, 2 is a water separator, 3 is a feed pump, 3a is a gear room, 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 part, 19 is a branch line, 20
is the lid, 21 is the relay, 22 is the coil, 23 is the a contact, 2
4 indicates a starting switch.

Claims (1)

[Scope of Claims] 1) A check valve is provided on the suction side line of the feed pump in the fuel system of the diesel engine to allow only the flow of fuel toward the feed pump, and a check valve in the line is provided. A bypass line connecting upstream and downstream locations is formed, a pump is provided on the bypass line, and the circuit that supplies power to the pump is energized by switching the starting switch of the diesel engine to the pre-heat side and the start side. A fuel system circulation device for a diesel engine, characterized in that a relay a contact point is provided. 2) Form a branch line that branches from the suction side line of the feed pump in the diesel engine fuel system and leads to the gallery chamber of the feed pump, and in the branch line,
A check valve that only allows fuel to flow toward the gallery room is provided, and a pump is provided upstream of the check valve in the branch line, and a circuit that supplies power to the pump is connected to a diesel engine starting switch preamp. - A fuel system circulation device for a diesel engine, characterized in that it is provided with a relay a contact that is energized by a switching operation to the heat side and the start side.