JP2010216425A - Fuel supply device for engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce device cost by common use of a pump for supplying fuel in an exhaust pipe such as a HC dosing pump and a pump used for a device for supplying fuel into a cylinder, and improve durability by suppressing rise of fuel pressure at an outlet of the common pump. <P>SOLUTION: When signal commanding air bleed of a passage 10 for supplying fuel into a cylinder is generated, a common pump 60 is operated, a first open close valve 71 is set to an open state, a second open close valve 17 is set to a close state, and fuel is supplied to the passage for supplying fuel into the cylinder from the common pump through a fuel supply passage 70 for air bleed. The common pump generating signal commanding fuel supply into an exhaust pipe 4 is operated, the second open close valve is set to an open state and the first open close valve is set to a close state, and fuel is supplied to the exhaust pipe 4 from the common pump through the passage 20 for supplying fuel into the exhaust pipe. If fuel pressure at a delivery port 60a side of the common pump extremely rises, fuel pressure at a delivery port side of the common pump reaches prescribed relief pressure, and fuel at the delivery port side of the common pump is relieved to a suction port 60b side of the common pump or a fuel tank 5 from a relief valve 180. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an engine fuel supply device, and more particularly to an engine fuel supply device that performs air bleeding in a cylinder fuel supply passage and fuel supply into an exhaust pipe.

(Conventional technology)
FIGS. 14A and 14B each illustrate the configuration of a conventional engine fuel supply apparatus 100.

FIG. 14A shows an in-cylinder fuel supply device 110 that supplies fuel into the cylinder of the engine 2 via the feed pump 1. On the other hand, FIG. 14 (b) shows an HC (hydrocarbon) dosing device 120 that supplies fuel to the exhaust pipe 4 of the engine 2.

  In the in-cylinder fuel supply device 110 shown in FIG. 14A, the fuel in the fuel tank 5 is sucked by the feed pump 1 via the supply path 10a, the prefilter 6, and the supply path 10b. The feed pump 1 boosts the fuel to a predetermined fuel pressure, for example, about 3 to 5 kgf / cm <2>, and discharges the fuel to the supply passage 10c. The fuel boosted by the feed pump 1 is sucked into the supply pump 8 through the supply path 10c, the main filter 7, and the supply path 10d. The supply pump 8 further raises the fuel to a predetermined fuel pressure, for example, about 1000 to 1600 kgf / cm 2 and discharges the fuel to the supply passage 10e. The fuel boosted by the supply pump 8 is supplied into the cylinder of the engine 2 via a supply path 10e and a common rail and an injector (not shown). High-pressure fuel is injected into the cylinder of the engine 2 and the engine 2 is operated. When the fuel overflows in the supply pump 8, the overflowed fuel is discharged to the fuel tank 5 through the overflow fuel discharge path 11.

When so-called "gas shortage", that is, when the engine 2 is running, the fuel in the fuel tank 5 is insufficient and no fuel is supplied to the engine 2, or the prefilter 6 or the main filter 7 is replaced. Sometimes, air (air) may be mixed into the cylinder fuel supply passage 10. When air enters the cylinder fuel supply passage 10, the fuel pressure of the fuel flowing through the cylinder fuel supply passage 10 does not rise to an appropriate value for a long time until the air is completely removed from the cylinder fuel supply passage 10, and the engine 2 becomes unsatisfactory or the engine itself is difficult to start. For this reason, every time the fuel filter is replaced, for example, every time the engine 2 is operated for 500 hours or when the gas runs out, the priming pump 9 is operated to release air, and then the engine 2 is operated. There is a need.

When the switch 12 is turned on, the relay 13 is energized and the priming pump 9 is activated. Since it is necessary to perform air bleeding in a state where the engine 2 is not operated, the priming pump 9 operates while the engine 2 is not operating.

When the priming pump 9 is activated, the fuel in the fuel tank 5 is sucked into the suction port 9b of the priming pump 9 via the supply path 10a, the prefilter 6, the supply path 10b, and the suction fuel supply path 30. The priming pump 9 boosts the fuel to a predetermined fuel pressure suitable for air venting, for example, about 3 to 5 kgf / cm <2>, and discharges the fuel from the discharge port 9a to the air venting fuel supply path 31. The fuel pressurized by the priming pump 9 is pumped to the main filter 7 through the air venting fuel supply passage 31, passes through the supply pump 8, and is discharged to the fuel tank 5 through the overflow fuel discharge passage 11. The fuel boosted by the priming pump 9 is pumped to the main filter 7 through the air venting fuel supply passage 31 and discharged to the fuel tank 5 through the air venting fuel discharge passage 32. As a result, air is extracted from the cylinder fuel supply passage 10.

Next, the HC dosing device 120 shown in FIG.

With the recent tightening of exhaust gas regulations of the engine 2, a diesel particulate filter 14 as an exhaust gas aftertreatment device is provided in the exhaust pipe 4. In the diesel particulate filter 14, particulate matter (PM: particulate matter) in the exhaust gas of the engine 2 is collected, and diffusion of PM to the atmosphere is suppressed.

However, if particulate matter PM is collected by the diesel particulate filter 14 over a long period of time, the pressure loss in the exhaust pipe 4 increases, making it difficult to exhaust the exhaust gas or clogging the filter. The function of the diesel particulate filter 14 is deteriorated. For this reason, for example, every time the engine 2 operates for several tens of hours, it is necessary to remove the particulate matter PM deposited on the diesel particulate filter 14 and regenerate the function of the diesel particulate filter 14. There are various methods for regenerating the diesel particulate filter 14, and one method is an “HC dosing” method.

That is, in order to remove the particulate matter PM deposited on the diesel particulate filter 14, it is only necessary to raise the temperature of the exhaust gas and burn soot in the particulate matter PM clogged in the filter. know. For this purpose, an oxidation catalyst 15 is disposed in the exhaust pipe 4 in front of the diesel particulate filter 14 and fuel is injected into the oxidation catalyst 15 to oxidize the HC (hydrocarbon) in the fuel and the oxidation catalyst 15. This generates heat and raises the temperature of the exhaust gas.

The HC dosing device 120 is provided to supply fuel into the exhaust pipe 4 for regeneration of the diesel particulate filter 14.

Based on the detection signal of the sensor 51, the controller 50 determines that it is time to regenerate the exhaust gas aftertreatment device (hereinafter simply referred to as “regeneration time”), and at that time, the fuel into the exhaust pipe 4 is determined. A signal for commanding the supply is applied to the HC dosing pump 16 and the valves 17 and 19. As a result, the HC dosing pump 16 is activated and the valves 17 and 19 are opened. Since it is necessary to supply the fuel to the exhaust pipe 4 while the engine 2 is operating and exhaust gas is being exhausted, the HC dosing pump 16 operates while the engine 2 is operating.

When the HC dosing pump 16 is activated, the fuel in the fuel tank 5 is sucked into the suction port 16 b of the HC dosing pump 16 through the suction fuel supply passage 41.

The HC dosing pump 16 boosts the fuel to a predetermined fuel pressure suitable for supply into the exhaust pipe, for example, about 7 to 10 kgf / cm @ 2, and discharges the fuel from the discharge port 16a to the supply path 20a. The fuel boosted by the HC dosing pump 16 is injected and supplied into the exhaust pipe 4 through the supply path 20a, the second on-off valve 17, the flow rate control valve 19, the supply path 20b, and the nozzle 21.

(Prior art found in patent literature)
Patent Document 1 below discloses an invention in which a pump dedicated to air venting is provided separately from the feed pump, and this pump is operated to air vent the fuel system of the diesel engine.

  In addition, inventions relating to the above-described HC dosing device are described in Patent Documents 2 and 3 below.

Also, as in the above-described HC dosing device, there is a technique found in Patent Document 4 below as a technique for supplying fuel to the exhaust pipe. In this Patent Document 4, a catalyst for removing NOx in the exhaust gas is provided in the exhaust pipe, and in order to increase the removal rate of NOx by this catalyst, light oil fuel as a reducing agent of the catalyst is placed in the exhaust pipe in a high pressure state. An invention is described in which the fuel is injected and supplied.

JP-A-2-256869 Japanese Patent Publication No. 5-34486 JP 2000-193824 A JP-A-8-68315

  As described above, the HC dosing device 120 is provided independently of the in-cylinder fuel supply device 110, and the HC dosing pump 16 is different from the various pumps 1, 8, 9 used in the in-cylinder fuel supply device 110. It is necessary to prepare a special one separately.

  The present invention has been made in view of such a situation, and the pump for supplying fuel in the exhaust pipe such as the HC dosing pump is also used as the pump used in the cylinder fuel supply device 110, thereby reducing the device cost. This is a problem to be solved.

  Another object of the present invention is to improve the reliability of the dual-purpose pump by avoiding a high fuel pressure on the outlet side of the dual-purpose pump.

The first invention is
A fuel supply device for an engine provided with an in-cylinder fuel supply path for supplying fuel into a cylinder of the engine via a fuel pump, and an exhaust pipe fuel supply path for supplying fuel into the exhaust pipe of the engine,
A dual-purpose pump that is provided separately from the fuel pump and serves both as an air vent for the cylinder fuel supply passage and a fuel supply to the exhaust pipe;
An air venting fuel supply path that communicates the discharge port of the dual-purpose pump and the fuel supply path in the cylinder;
An exhaust pipe fuel supply passage communicating the discharge port of the dual-purpose pump and the exhaust pipe;
A first on-off valve provided on the air venting fuel supply path and opening and closing the air venting fuel supply path;
A second on-off valve provided on the fuel supply path in the exhaust pipe and opening and closing the fuel supply path in the exhaust pipe;
When a signal for commanding air removal from the cylinder fuel supply passage is generated, the dual-purpose pump is operated, the first on-off valve is opened, the second on-off valve is closed, and fuel is discharged from the dual-purpose pump. And supplying the cylinder fuel supply passage through the air vent fuel supply passage,
When a signal for commanding fuel supply into the exhaust pipe is generated, the dual-purpose pump is operated, the second on-off valve is opened, the first on-off valve is closed, and fuel is discharged from the dual-purpose pump. Control means for supplying to the exhaust pipe via the in-pipe fuel supply path;
When the fuel pressure on the discharge port side of the dual-purpose pump reaches the specified relief pressure, a relief valve is provided to relieve the fuel on the discharge port side of the dual-purpose pump to the suction port side of the dual-purpose pump or to the fuel tank. And

The second invention is
A fuel supply device for an engine provided with an in-cylinder fuel supply path for supplying fuel into a cylinder of the engine via a fuel pump, and an exhaust pipe fuel supply path for supplying fuel into the exhaust pipe of the engine,
A dual-purpose pump that is provided separately from the fuel pump and serves both as an air vent for the cylinder fuel supply passage and a fuel supply to the exhaust pipe;
An air venting fuel supply path that communicates the discharge port of the dual-purpose pump and the fuel supply path in the cylinder;
An exhaust pipe fuel supply passage communicating the discharge port of the dual-purpose pump and the exhaust pipe;
A throttle provided on the air supply fuel supply passage;
A first on-off valve provided on the fuel supply path in the exhaust pipe and opening and closing the fuel supply path in the exhaust pipe;
When a signal to command air removal from the in-cylinder fuel supply path is generated, the dual-purpose pump is operated, the first on-off valve is closed, fuel is discharged from the dual-purpose pump, and the throttle on the air supply fuel supply path is Through the cylinder fuel supply path,
When a signal for instructing fuel supply into the exhaust pipe is generated, the dual-purpose pump is operated, the first on-off valve is opened, and the fuel from the dual-purpose pump is supplied to the exhaust pipe through the exhaust pipe fuel supply passage. Control means for supplying to
When the fuel pressure on the discharge port side of the dual-purpose pump reaches the specified relief pressure, a relief valve is provided to relieve the fuel on the discharge port side of the dual-purpose pump to the suction port side of the dual-purpose pump or to the fuel tank. And

The third invention is the first invention,
A first suction fuel supply path that communicates a supply path on the suction port side of the fuel pump and a suction port of the dual-purpose pump among the in-cylinder fuel supply path;
A second suction fuel supply path that communicates a supply path on the discharge port side of the fuel pump and a suction port of the dual-purpose pump among the fuel supply paths in the cylinder;
A first suction on-off valve provided on the first suction fuel supply path and opening and closing the first suction fuel supply path;
A second suction on-off valve provided on the second suction fuel supply path, which opens and closes the second suction fuel supply path;
When a signal to command air removal from the cylinder fuel supply passage is generated, the first suction on-off valve is opened, the second suction on-off valve is closed, and the fuel pump suction side From the first suction fuel supply passage to the fuel suction port of the dual-purpose pump,
When a signal for commanding fuel supply into the exhaust pipe is generated, the second suction on-off valve is opened, the first suction on-off valve is closed, and the fuel pump discharge port side And a control means for sucking the fuel into the suction port of the dual-purpose pump through the two suction fuel supply passages.

A fourth invention is the second invention,
A first suction fuel supply path that communicates a supply path on the suction port side of the fuel pump and a suction port of the dual-purpose pump among the in-cylinder fuel supply path;
A second suction fuel supply path that communicates a supply path on the discharge port side of the fuel pump and a suction port of the dual-purpose pump among the fuel supply paths in the cylinder;
A first suction on-off valve provided on the first suction fuel supply path and opening and closing the first suction fuel supply path;
A second suction on-off valve provided on the second suction fuel supply path, which opens and closes the second suction fuel supply path;
When a signal to command air removal from the cylinder fuel supply passage is generated, the first suction on-off valve is opened, the second suction on-off valve is closed, and the fuel pump suction side From the first suction fuel supply passage to the fuel suction port of the dual-purpose pump,
When a signal for commanding fuel supply into the exhaust pipe is generated, the second suction on-off valve is opened, the first suction on-off valve is closed, and the fuel pump discharge port side And a control means for sucking the fuel into the suction port of the dual-purpose pump through the two suction fuel supply passages.

A fifth invention is the first invention,
The first on-off valve is opened and closed by a fuel pressure signal.

A sixth invention is the first invention,
The first on-off valve is opened and closed by an electrical signal.

A seventh invention is the third invention,
The first on-off valve, the first suction on-off valve, and the second suction on-off valve are opened and closed by an electrical signal.

In an eighth aspect based on the second aspect,
The aperture is a variable aperture.

A ninth invention is the first invention,
A suction fuel supply passage communicating with the suction port of the dual-purpose pump is provided,
Check valve or on-off valve that blocks the flow of fuel from the air venting fuel supply path to the suctioning fuel supply path via the dual-purpose pump in either the air venting fuel supply path or the dual-purpose pump or the suction fuel supply path Is provided.

The tenth invention is the fourth invention,
The first suction on-off valve and the second suction on-off valve are opened and closed by an electrical signal.
The eleventh invention is
A dual-purpose pump that serves as both the air vent for the cylinder fuel supply passage and the fuel supply to the exhaust pipe;
At the time of air bleeding, the fuel is supplied from the dual-purpose pump to the cylinder fuel supply passage while preventing the fuel supply from the dual-purpose pump into the exhaust pipe.
Means for supplying fuel from the dual-purpose pump into the exhaust pipe while preventing or suppressing the supply of fuel from the dual-purpose pump to the cylinder fuel supply path when fuel is supplied to the exhaust pipe;
A fuel supply device for an engine equipped with a relief valve that relieves fuel on the discharge port side of the dual-purpose pump to a lower pressure side than the discharge pressure of the dual-purpose pump when the discharge pressure of the dual-purpose pump reaches a predetermined relief pressure. It is characterized by being.
In a twelfth aspect based on the eleventh aspect,
The low pressure side of the discharge pressure of the dual-purpose pump is a suction port side of the dual-purpose pump or a fuel tank.

In the first invention, as shown in FIG. 1, an engine fuel supply device 100 includes an in-cylinder fuel supply path 10 that supplies fuel into a cylinder of an engine 2 via a fuel pump (feed pump) 1, and a fuel. Is provided in the exhaust pipe 4 of the engine 2.

The dual-purpose pump 60 is provided separately from the fuel pump 1, and serves as both the air vent for the cylinder fuel supply passage 10 and the fuel supply to the exhaust pipe 4.

  The discharge port 60 a of the dual-purpose pump 60 and the in-cylinder fuel supply path 10 are communicated with each other by an air bleeding fuel supply path 70.

  The discharge port 60 a of the dual-purpose pump 60 and the exhaust pipe 4 are communicated with each other through the exhaust pipe fuel supply path 20.

  A first on-off valve 71 is provided on the air vent fuel supply path 70, and the first on-off valve 71 opens and closes the air vent fuel supply path 70.

  A second on-off valve 17 is provided on the exhaust pipe fuel supply path 20, and the second on-off valve 17 opens and closes the exhaust pipe fuel supply path 20.

  When a signal for commanding air removal from the cylinder fuel supply passage 10 is generated, the control means 50 operates the dual-purpose pump 60 to open the first on-off valve 71 and close the second on-off valve 17. Then, the fuel is supplied from the dual-purpose pump 60 to the in-cylinder fuel supply passage 10 via the air bleeding fuel supply passage 70. Further, when a signal for commanding fuel supply into the exhaust pipe 4 is generated, the control means 50 operates the dual-purpose pump 60 to open the second on-off valve 17 and close the first on-off valve 71. Thus, the fuel is supplied from the dual-purpose pump 60 to the exhaust pipe 4 via the fuel supply passage 20 in the exhaust pipe.

Here, when the supply of fuel into the exhaust pipe 4 is started, the fuel pressure in the supply passage 20a on the discharge port 60a side of the dual-purpose pump 60 may become very high. As described above, when the fuel pressure in the supply passage 20a on the discharge port 60a side of the dual-purpose pump 60 is very high when the fuel is supplied into the exhaust pipe 4, the discharge port 60a side of the dual-purpose pump 60 is provided. The fuel pressure reaches the predetermined relief pressure, and the fuel on the discharge port 60a side of the dual-purpose pump 60 is relieved from the relief valve 180 to the suction port 60b side of the dual-purpose pump 60 or to the fuel tank 5. Thereby, the increase in the fuel pressure in the supply path 20a on the discharge port 60a side of the dual-purpose pump 60 can be suppressed. As a result, the durability of the dual-purpose pump 60 is improved.

  As described above, according to the first invention, the dual-purpose pump 60 can be used to release air from the in-cylinder fuel supply passage 10 and to supply fuel into the exhaust pipe 4, thereby reducing the device cost. be able to.

  Moreover, it can avoid that the fuel pressure of the exit side of the combined use pump 60 becomes high pressure, and the reliability of the combined use pump 60 increases.

In the second invention, a throttle 171 is provided on the air supply fuel supply passage 70 instead of the first on-off valve 71. When the throttle 171 is provided, unlike the case where the first opening / closing valve 71 is provided, the opening / closing control by the control means 50 is not required. For this reason, the system which also serves as a pump can be made into a simple structure, and an apparatus cost can be reduced further.

Here, when the filter 7 in the in-cylinder fuel supply path 10 is clogged during operation of the engine 2, the fuel pressure on the discharge port 60a side of the dual-purpose pump 60 communicating with the throttle 171 may become very high. In this way, when the fuel pressure on the discharge port 60a side of the dual-purpose pump 60 is very high during the operation of the engine 2, the fuel pressure on the discharge port 60a side of the dual-purpose pump 60 reaches a predetermined relief pressure, and the relief valve 180 The fuel on the discharge port 60 a side of the dual-purpose pump 60 is relieved to the suction port 60 b side of the dual-purpose pump 60 or the fuel tank 5. Thereby, the increase in the fuel pressure on the discharge port 60a side of the dual-purpose pump 60 can be suppressed. As a result, the durability of the dual-purpose pump 60 is improved.

  As described above, according to the second invention, the cost of the apparatus can be reduced to the same level as or more than that of the first invention, and the dual-purpose pump 60 can be avoided by avoiding a high fuel pressure on the outlet side of the dual-purpose pump 60. Can improve the reliability.

In the third and fourth inventions, the supply passage 10b on the intake port 1b side of the fuel pump (feed pump) 1 and the intake port 60b of the dual-purpose pump 60 in the in-cylinder fuel supply passage 10 are the first intake fuel. The supply path 80 communicates.

  Of the in-cylinder fuel supply path 10, the supply path 10 c on the discharge port 1 a side of the fuel pump 1 and the suction port 60 b of the dual-purpose pump 60 are connected by a second suction fuel supply path 81.

On the first suction fuel supply passage 80, a first suction on-off valve 82 that opens and closes the first suction fuel supply passage 80 is provided.

On the second suction fuel supply passage 81, a second suction on-off valve 83 that opens and closes the second suction fuel supply passage 81 is provided.

When a signal for commanding air removal from the in-cylinder fuel supply passage 10 is generated, the control means 50 opens the first suction on-off valve 82 and closes the second suction on-off valve 83 to close the fuel. Fuel is sucked into the suction port 60 b of the dual-purpose pump 60 from the suction port 1 b side of the pump 1 through the first suction fuel supply path 80. Further, the control means 50 opens the second suction on-off valve 83 and closes the first suction on-off valve 82 when a signal for commanding fuel supply into the exhaust pipe 4 is generated. Thus, the fuel is sucked into the suction port 60 b of the dual-purpose pump 60 from the discharge port 1 a side of the fuel pump 1 through the second suction fuel supply passage 81.

  According to the third and fourth inventions, when fuel is supplied into the exhaust pipe 4, the fuel is sucked into the dual-purpose pump 60 from the discharge port 1 a side of the fuel pump 1, and the fuel enters the exhaust pipe 4. Boost the fuel pressure suitable for fuel supply.

When fuel is supplied into the exhaust pipe 4, the engine 2 is operating and the fuel pump (feed pump) 1 is operating. The dual-purpose pump 60 further boosts the fuel that has already been boosted to a predetermined pressure (about 3 to 5 kgf / cm 2) by the fuel pump 1 to a fuel pressure (about 7 to 10 kgf / cm 2) suitable for fuel supply into the exhaust pipe 4. Therefore, the boosting capability of the dual-purpose pump 60 can be lower than when boosting the fuel whose fuel pressure has not increased.

On the other hand, air removal from the cylinder fuel supply passage 10 is performed mainly when the engine 2 is not in operation. According to the third and fourth inventions, when the air in the cylinder fuel supply passage 10 is vented, the fuel in the fuel tank 5 is sucked into the dual-purpose pump 60 from the suction port 1b side of the fuel pump 1, so that the engine Even when 2 is not operating and the fuel pump 1 is not operating, the fuel can be satisfactorily sucked from the fuel tank 5 on the suction 1b side of the fuel pump 1. However, the fuel pressure (about 4 kgf / cm 2) when the fuel (atmospheric pressure) in the fuel tank 5 is increased by the dual-purpose pump 60 is already increased to a predetermined pressure (about 3 to 5 kgf / cm 2) by the operation of the fuel pump 1. The fuel pressure when the pressurized fuel is further increased (lower than about 7 to 9 kgf / cm 2) is lower than that when the fuel supply passage 10 in the cylinder is originally supplied with fuel into the exhaust pipe 4. Since the fuel pressure is sufficient, the air in the cylinder fuel supply passage 10 can be sufficiently removed.

According to the third and fourth inventions, the boosting capability of the dual-purpose pump 60 can be kept low, and the dual-purpose pump 60 can be downsized.

In the fifth invention, the first on-off valve 71 is opened and closed by a fuel pressure signal.

In the sixth invention, the first on-off valve 71 is opened and closed by an electrical signal.

In the seventh invention, the first on-off valve 71, the first suction on-off valve 82, and the second suction on-off valve 83 are opened and closed by an electrical signal.

The eighth invention is characterized in that the diaphragm 171 is a variable diaphragm.

In the ninth aspect of the invention, the suction fuel supply passage 30 communicating with the suction port 60b of the dual-purpose pump 60 is provided. A check valve 172 (or an open / close valve) is provided in either the air vent fuel supply path 70, the dual-purpose pump 60, or the suction fuel supply path 30. The check valve 172 (or on-off valve) blocks the flow of fuel from the air bleeding fuel supply path 70 to the intake fuel supply path 30 via the dual-purpose pump 60. As a result, while the engine 2 is in operation, the fuel passes through the throttle 171 on the air venting fuel supply passage 70 and passes through the dual-purpose pump 60 and the suction fuel supply passage 30 to the cylinder fuel supply passage 10. Reflux can be prevented.

In the tenth invention, the first suction opening / closing valve 82 and the second suction opening / closing valve 83 are opened / closed by an electric signal.

The eleventh and twelfth inventions are inventions of a superordinate concept of the first invention.

FIG. 1 is a configuration diagram of an engine fuel supply device according to an embodiment, and is a diagram illustrating an operation when air bleeding is performed when the engine is not operating. FIG. 2 is a diagram for explaining the operation of the apparatus shown in FIG. 1 when neither air bleeding nor HC dosing is performed while the engine is running. FIG. 3 is a diagram illustrating an operation when HC dosing is performed while the engine is operating in the apparatus of FIG. FIG. 4 is a configuration diagram when the first on-off valve shown in FIG. 1 is configured by a valve that operates when an electrical command signal is given. FIG. 5 is a configuration diagram of an engine fuel supply apparatus according to an embodiment different from that in FIG. 1, and is a diagram illustrating an operation when air bleeding is performed when the engine is not operating. FIG. 6 is a diagram for explaining the operation of the apparatus shown in FIG. 5 when neither air bleeding nor HC dosing is performed while the engine is running. FIG. 7 is a diagram for explaining the operation when HC dosing is performed while the engine is operating in the apparatus of FIG. FIG. 8 is a configuration diagram when the first on-off valve, the first suction on-off valve, and the second suction on-off valve shown in FIG. 5 are configured by valves that operate when an electric command signal is given. . FIG. 9A is a functional block diagram of the controller. FIGS. 9B and 9C are flowcharts for explaining the operation of the embodiment shown in FIGS. 1, 2 and 3, and FIG. 9B shows the processing accompanying the operation of the switch. FIG. 9C shows a process performed by the controller. FIG. 10 is a diagram corresponding to FIGS. 1A to 3 and is a configuration diagram of an embodiment in which a throttle is provided instead of the first on-off valve. FIG. 11 is a configuration diagram of an embodiment in which the diaphragm in FIG. 10 is a variable diaphragm. FIG. 12 is a diagram corresponding to FIGS. 5, 6, and 7, and is a configuration diagram of an embodiment in which a throttle is provided instead of the first on-off valve. FIG. 13 is a diagram corresponding to FIG. 8 and is a configuration diagram of an embodiment in which a throttle is provided instead of the first on-off valve. FIGS. 14A and 14B are configuration diagrams of the prior art.

  Embodiments of a fuel supply apparatus for an engine according to the present invention will be described below with reference to the drawings.

  FIG. 1A shows a configuration diagram of an engine fuel supply apparatus 100 according to an embodiment.

As shown in FIG. 1 (a), an engine fuel supply apparatus 100 according to the embodiment includes an in-cylinder fuel supply path 10 that supplies fuel into a cylinder of the engine 2 via a feed pump 1, and fuel is supplied to the engine 2. The exhaust pipe fuel supply passage 20 is supplied to the exhaust pipe 4. As the feed pump 1, for example, a trochoid pump is used.

  The in-cylinder fuel supply path 10 communicates the fuel tank 5 and the inside of the cylinder of the engine 2. A fuel tank 5, a pre-filter 6, a feed pump 1, a main filter 7, a supply pump 8 and an engine 2 are arranged in the cylinder fuel supply path 10. The engine 2 is a diesel engine.

The feed pump 1 and the supply pump 8 constitute a fuel pump. The prefilter 6 is a fuel filter including a water separator, and is provided to separate and collect water mixed in the fuel and collect dust mixed in the fuel. The main filter 7 is a fuel filter and is provided for collecting dust mixed in the fuel.

The in-cylinder fuel supply path 10 includes supply paths 10a, 10b, 10c, 10d, and 10e. The fuel tank 5 and the prefilter 6 are communicated with each other through a supply path 10a, the prefilter 6 and the feed pump 1 are communicated with each other through a supply path 10b, and the feed pump 1 and the main filter 7 are communicated with each other through a supply path 10c. 7 and the supply pump 8 are communicated by a supply path 10d, and the supply pump 8 and the engine 2 are communicated by a supply path 10e. The supply pump 8 and the fuel tank 5 are communicated with each other by an overflow fuel discharge path 11. The overflow fuel discharge passage 11 is provided with a check valve 28 that allows only the flow of fuel from the supply pump 8 to the fuel tank 5.

The dual-purpose pump 60 is provided separately from the feed pump 1. The dual-purpose pump 60 is used for both the air venting of the in-cylinder fuel supply passage 10 and the fuel supply to the exhaust pipe 4, that is, HC dosing.

The dual-purpose pump 60 is an electric pump. The switch 12, the relay 13, and the dual-purpose pump 60 are electrically connected. The dual-purpose pump 60 operates when the relay 13 is energized. When the switch 12 is turned on to command air removal from the in-cylinder fuel supply passage 10, a signal for instructing air removal from the cylinder fuel supply passage 10 is generated. This signal is applied to the relay 13 and the relay 13 is energized. The dual-purpose pump 60 is activated by energizing the relay 13.

Air bleeding is performed using the suction fuel supply path 30, the air bleeding fuel supply path 70, the air bleeding fuel discharge path 32, and the overflow fuel discharge path 11.

  The supply passage 10 b and the suction port 60 b of the dual-purpose pump 60 are communicated with each other by a suction fuel supply passage 30. Here, the reason why the fuel is sucked into the dual-purpose pump 60 from the supply passage 10b on the outlet side of the pre-filter 6 is to discharge the clean fuel that has passed through the pre-filter 6 from the dual-purpose pump 60. .

The discharge port 60 a of the dual-purpose pump 60 and the main filter 7 of the in-cylinder fuel supply path 10 are communicated with each other by an air bleeding fuel supply path 70. A first on-off valve 71 is provided on the air vent fuel supply path 70, and the first on-off valve 71 opens and closes the air vent fuel supply path 70. The first on-off valve 71 is a check valve that allows only the flow in the direction from the dual-purpose pump 60 to the main filter 7. In the embodiment, the air vent fuel supply path 70 communicates the discharge port 60a of the dual-purpose pump 60 and the main filter 7 of the in-cylinder fuel supply path 10, but the air vent fuel supply path 70 The discharge port 60a of the dual-purpose pump 60 and the supply passage 10c of the in-cylinder fuel supply passage 10 may communicate with each other, and the air supply fuel supply passage 70 may be connected to the discharge port 60a of the dual-purpose pump 60 and the cylinder. It may communicate with the supply path 10d of the internal fuel supply path 10.

The main filter 7 and the fuel tank 5 are communicated with each other by an air bleeding fuel discharge path 32. A throttle 29 is provided in the air vent fuel discharge path 32.

The fuel in the fuel tank 5 is sucked into the feed pump 1 through the supply path 10a, the prefilter 6, and the supply path 10b. The feed pump 1 boosts the fuel to a predetermined fuel pressure, for example, about 3 to 5 kgf / cm <2>, and discharges the fuel to the supply passage 10c. The fuel boosted by the feed pump 1 is sucked into the supply pump 8 through the supply path 10c, the main filter 7, and the supply path 10d. The supply pump 8 further raises the fuel to a predetermined fuel pressure, for example, about 1000 to 1600 kgf / cm 2 and discharges the fuel to the supply passage 10e. The fuel boosted by the supply pump 8 is supplied into the cylinder of the engine 2 via a supply path 10e and a common rail and an injector (not shown). High-pressure fuel is injected into the cylinder of the engine 2 and the engine 2 is operated. When the fuel overflows in the supply pump 8, the overflowed fuel is discharged to the fuel tank 5 through the overflow fuel discharge path 11.

  An inlet 180b of a relief valve 180 is communicated with the supply passage 20a on the discharge port 60a side of the dual-purpose pump 60, and a relief valve 180 is connected to the suction fuel supply passage 30 on the suction port 60b side of the dual-purpose pump 60. The outlet 180a is in communication. When the fuel pressure on the discharge port 60 a side of the dual-purpose pump 60 reaches a predetermined relief pressure, the relief valve 180 supplies the fuel on the discharge port 60 a side of the dual-purpose pump 60 to the suction fuel supply passage 30 on the suction port 60 b side of the dual-purpose pump 60. Relief.

A diesel particulate filter 14 as an exhaust gas after-treatment device is provided in the exhaust pipe 4 of the engine 2. In the diesel particulate filter 14, particulate matter (PM: particulate matter) in the exhaust gas of the engine 2 is collected, and diffusion of PM to the atmosphere is suppressed.

An oxidation catalyst 15 is disposed upstream of the diesel particulate filter 14 in the exhaust pipe 4. When fuel is injected into the oxidation catalyst 15 (HC dosing), HC (hydrocarbon) in the fuel and the oxidation catalyst 15 undergo an oxidation reaction to generate heat, and the temperature of the exhaust gas rises. When the temperature of the exhaust gas increases, soot in the particulate matter PM clogged with the filter of the diesel particulate filter 14 is combusted, and the function of the diesel particulate filter 14 is regenerated.

The exhaust pipe fuel supply passage 20 is provided to regenerate the diesel particulate filter 14 by supplying fuel into the exhaust pipe 4 (HC dosing).

The exhaust pipe fuel supply path 20 communicates the dual-purpose pump 60 and the exhaust pipe 4.

The dual-purpose pump 60, the second on-off valve 17, the third on-off valve 18, the flow control valve 19, and the nozzle 21 are disposed in the exhaust pipe fuel supply path 20.

The exhaust pipe fuel supply path 20 includes supply paths 20a, 20b, and 20c.

The discharge port 60a of the dual-purpose pump 60 and the second on-off valve 17 are in communication with each other through the supply path 20a. The second on-off valve 17 opens and closes the exhaust pipe fuel supply passage 20 in accordance with an electrical command signal given from the controller 50.

The outlet 17a of the second on-off valve 17, the third on-off valve 18, and the inlet 19b of the flow control valve 19 are communicated with each other through a supply path 20b. The flow control valve 19 and the nozzle 21 are communicated with each other through a supply path 20c. The nozzle 21 is attached to the exhaust pipe 4 and injects fuel into the exhaust pipe 4. The nozzle 21 is provided between the oxidation catalyst 15 and an exhaust manifold (not shown). The nozzle 21 may be provided in the exhaust manifold.

The third on-off valve 18 and the fuel tank 5 are communicated with each other by a fuel discharge path 40. When the fuel overflows at the third on-off valve 18, the overflowed fuel is discharged to the fuel tank 5 through the fuel discharge path 40.

In order to inject the high-pressure fuel onto the oxidation catalyst 15 to promote atomization of the fuel and cause the oxidation reaction between the HC and the oxidation catalyst 15, the fuel pressure required at the time of bleeding from the dual-purpose pump 60 during HC dosing. It is necessary to discharge fuel having a fuel pressure higher than (about 3 to 5 kgf / cm 2), for example, about 7 to 10 kgf / cm 2.

Each valve 17, 18, 19 is composed of an electromagnetic valve that operates by applying an electrical signal. In addition, you may comprise each valve 17, 18, and 19 with the valve | bulb of a hydraulic pilot system which act | operates by giving a hydraulic signal.

The dual-purpose pump 60, the valves 17, 18, 19 and the controller 50 are electrically connected. The controller 50 is electrically connected to the relay 13. When the engine 2 is not in operation, the electrical command signals from the controller 50 to the valves 17, 18, and 19 are turned off, the valves 17, 18, and 19 are closed and supplied from the controller 50 to the relay 13. The electrical command signal for energizing the relay 13 is turned off.

The amount of fuel injected from the nozzle 21 (fuel flow rate per unit time) is determined by the integrated value of the fuel pressure in the supply passage 20b and the time during which fuel is injected from the nozzle 21. For example, the flow control valve 19 is repeatedly turned on (opened) and turned off (closed) at a predetermined duty ratio, and while the flow control valve 19 is turned on (opened), fuel is supplied to the nozzle 21, and fuel is supplied from the nozzle 21. To spray. By accumulating the product of the time during which the flow control valve 19 is turned on (opened) and the fuel pressure at that time, the amount of fuel injected from the nozzle 21 is determined. The sensor 173 detects the fuel pressure in the supply path 20b. A detection signal of the sensor 173 is input to the controller 50. The controller 50 outputs a control signal to the flow control valve 19 based on the detection signal of the sensor 173 so that the injection amount of the fuel injected from the nozzle 21 becomes a desired value, and the opening of the flow control valve 19 is controlled. Control on / off.

  FIG. 1B partially shows a configuration diagram when the function of the flow control valve 19 is incorporated in the nozzle 21. In this case, the sensor 173 is provided in a supply path 20 b ′ that communicates the third on-off valve 18 and the nozzle 21. Based on the detection signal of the sensor 173, the controller 50 outputs a control signal to the nozzle 21 to control the nozzle 21 so that the amount of fuel injected from the nozzle 21 becomes a desired value.

The exhaust pipe 4 is provided with a sensor 51 for detecting the pressure of the exhaust gas of the engine 2 in the exhaust pipe 4 or the pressure difference between the pressure before and after the diesel particulate filter 14. A detection signal of the sensor 51 is input to the controller 50. Based on the detection signal of the sensor 51, the controller 50 determines that the reproduction time has come.

  An outlet 71 a of the first on-off valve 71 configured by a check valve is communicated with a supply path 20 b of an outlet 17 a of the second on-off valve 17 via a fuel pressure signal path 72.

  In the following, the pressure is represented by gauge pressure, the cracking pressure of the first on-off valve 71 is set to 2 kgf / cm2, the discharge pressure of the feed pump 1 is 3 kgf / cm2, and the discharge pressure of the dual-purpose pump 60 is 7 kgf / cm2. It explains as being. In addition, the numerical value of these pressure was illustrated in order to make description easy to understand, and this invention is not limited to these numerical values.

  FIG. 9A is a functional block diagram of the controller 50. FIGS. 9B and 9C are flowcharts for explaining the operation of the embodiment shown in FIGS. 1, 2, and 3, and FIG. 9B shows the processing accompanying the operation of the switch 12. FIG. 9C shows processing performed by the controller 50.

  The operation of the embodiment shown in FIGS. 1, 2 and 3 will be described below with reference to FIGS. 9 (a), 9 (b) and 9 (c). In addition, the black arrow in FIG.1, FIG.2, FIG.3 shows the flow of a fuel. The same applies to the embodiments shown in FIGS. 4, 5, 6, 7, and 8.

(Operation when bleeding air; Fig. 1)
When so-called "gas shortage", that is, when the engine 2 is running, the fuel in the fuel tank 5 is insufficient and no fuel is supplied to the engine 2, or the prefilter 6 or the main filter 7 is replaced. Sometimes, air (air) may be mixed into the cylinder fuel supply passage 10. When air enters the cylinder fuel supply passage 10, the fuel pressure of the fuel flowing through the cylinder fuel supply passage 10 does not rise to an appropriate value for a long time until the air is completely removed from the cylinder fuel supply passage 10, and the engine 2 becomes unsatisfactory or the engine itself is difficult to start. For this reason, it is necessary to release the air periodically every time the fuel filter is replaced, for example, every time the engine 2 is operated for 500 hours, or when the gas runs out, and then to operate the engine 2.

  The operator turns on the switch 12 to release air before the engine 2 is started and when the engine 2 is not in operation (YES in step 101 in FIG. 9B).

When the switch 12 is turned on, a signal for commanding air removal from the in-cylinder fuel supply passage 10 is generated and the relay 13 is energized. The dual-purpose pump 60 is activated by energizing the relay 13. When the dual-purpose pump 60 operates, the fuel in the fuel tank 5 is sucked into the suction port 60b of the dual-purpose pump 60 through the supply path 10a, the prefilter 6, the supply path 10b, and the suction fuel supply path 30. The dual-purpose pump 60 boosts the fuel to 7 kgf / cm 2 and discharges the fuel from the discharge port 60a to the air bleeding fuel supply path 70. Thus, the dual-purpose pump 60 operates while the engine 2 is not operating. The fuel pressure 7 kgf / cm 2 of the fuel discharged from the dual-purpose pump 60 acts on the inlet 71b of the first on-off valve 71 on the air vent fuel supply passage 70 (step 102 in FIG. 9B).

On the other hand, since the engine 2 is not in operation (determined NO in step 201 in FIG. 9C), the electrical command signals for the valves 17, 18, and 19 from the output unit 50c of the controller 50 are turned off. The valves 17, 18, and 19 are closed, and the electrical command signal for energizing the relay 13 that is supplied from the output unit 50 c of the controller 50 to the relay 13 is turned off, and the relay 13 is turned off. (Step 202 in FIG. 9C). However, as described above, the relay 13 is energized by turning on the switch 12 by the operator (step 102 in FIG. 9B).

Since the second on-off valve 17 is closed and the fuel supply path 20 in the exhaust pipe is thereby closed, the fuel discharged from the dual-purpose pump 60 is supplied into the exhaust pipe 4 through the fuel supply path 20 in the exhaust pipe. Is prevented.

Since the second on-off valve 17 is closed (YES at step 103 in FIG. 9B), the supply path 20b of the outlet 17a of the second on-off valve 17 is at atmospheric pressure. This is because, as will be described later, after the fuel is supplied to the exhaust pipe 4 via the supply path 20b, an operation for reducing the pressure in the supply path 20b to atmospheric pressure is performed. Since the supply path 20b of the outlet 17a of the second on-off valve 17 communicates with the outlet 71a of the first on-off valve 71 via the fuel pressure signal path 72, the outlet 71a of the first on-off valve 71 is at atmospheric pressure. It becomes. To open the first on-off valve 71, the fuel pressure acting on the inlet 71b of the first on-off valve 71 is 2 kgf obtained by adding the cracking pressure (2 kgf / cm 2) to the fuel pressure (atmospheric pressure) on the outlet 71a side. However, since the fuel pressure 7 kgf / cm 2 corresponding to the discharge pressure of the dual-purpose pump 60 is currently acting on the inlet 71b of the first on-off valve 71, the first on-off valve 71 Opens. As a result, the fuel pressurized by the dual-purpose pump 60 is pumped to the main filter 7 via the air vent fuel supply passage 70, passes through the supply pump 8, and is discharged to the fuel tank 5 via the overflow fuel discharge passage 11. Is done. The fuel pressurized by the dual-purpose pump 60 is pumped to the main filter 7 via the air vent fuel supply passage 70 and discharged to the fuel tank 5 via the air vent fuel discharge passage 32. As a result, air is extracted from the cylinder fuel supply passage 10 (step 104 in FIG. 9B).

As described above, air removal from the cylinder internal combustion supply passage 10 is performed when the engine 2 is not operating. In addition, according to this embodiment, the air is vented at a high fuel pressure (7 kgf / cm2) suitable for HC dosing, which is higher than the fuel pressure required at the time of air bleeding (about 3 to 5 kgf / cm2). Can be performed in a short time.

(Operation when the engine is running without air bleeding or HC dosing; Fig. 2)
When the operator turns on an engine start key switch (not shown), the engine 2 is started and the engine 2 is operated (determination YES in step 201 in FIG. 9C). As a result, as shown in FIG. 2, the feed pump 1 and the supply pump 8 connected to a crankshaft (not shown) of the engine 2 operate.

When the feed pump 1 operates, the fuel in the fuel tank 5 is sucked into the suction port 1b of the feed pump 1 through the supply path 10a, the prefilter 6, and the supply path 10b. The feed pump 1 boosts the fuel to a fuel pressure of 3 kgf / cm 2 and discharges the fuel from the discharge port 1a to the supply path 10c. The fuel boosted by the feed pump 1 is sucked into the supply pump 8 through the supply path 10c, the main filter 7, and the supply path 10d.

In the controller 50, the detection signal of the sensor 51 is input via the input unit 50a, and the arithmetic processing unit 50b determines whether or not the reproduction time is reached based on the detection signal of the sensor 51. As a result, if it is determined that the regeneration time has not come (NO in step 203 of FIG. 9C), the fuel supply into the exhaust pipe 4 is commanded via the output unit 50c of the controller 50. No signal is generated. For this reason, the electrical command signal for each of the valves 17, 18, and 19 is turned off from the output unit 50 c of the controller 50, the valves 17, 18, and 19 are closed, and the relay unit 13 is connected to the relay 13 from the output unit 50 c of the controller 50. On the other hand, the electric command signal for energizing the relay 13 is turned off, and the relay 13 is deenergized (step 204 in FIG. 9C).

Since the second on-off valve 17 is closed, the supply path 20b of the outlet 17a of the second on-off valve 17 is at atmospheric pressure. This is because, as will be described later, after the fuel is supplied to the exhaust pipe 4 via the supply path 20b, an operation for reducing the pressure in the supply path 20b to atmospheric pressure is performed. Since the supply path 20b of the outlet 17a of the second on-off valve 17 communicates with the outlet 71a of the first on-off valve 71 via the fuel pressure signal path 72, the outlet 71a of the first on-off valve 71 is at atmospheric pressure. It becomes.

When the air in the cylinder fuel supply passage 10 is not vented, the switch 12 is turned off (determination NO in step 101 in FIG. 9B). When the switch 12 is off, no signal for commanding air removal from the cylinder fuel supply passage 10 is generated, and the electrical command signal for energizing the relay 13 is off.

As described above, the electrical command signal for energizing the relay 13 is not applied to the relay 13, and the relay 13 is de-energized. As a result, the dual-purpose pump 60 does not operate.

For this reason, the discharge pressure of the dual-purpose pump 60 is not applied to the inlet 71b of the first open / close valve 71 from the discharge port 60a of the dual-purpose pump 60 via the air venting fuel supply passage 70. The pressure on the inlet 71b side of 71 is atmospheric pressure.

Thus, the pressure acting on the inlet 71b of the first on-off valve 71 is atmospheric pressure, and 2 kgf / cm2 obtained by adding the cracking pressure (2 kgf / cm2) to the atmospheric pressure acts on the outlet 71a side. Therefore, the first on-off valve 71 is closed. Therefore, the engine 2 operates without discharging fuel from the dual-purpose pump 60 to either the air vent fuel supply passage 70 or the exhaust pipe fuel supply passage 20.

(Operation during HC dosing; Fig. 3)
When the operator turns on an engine start key switch (not shown), the engine 2 is started and the engine 2 is operated (determination YES in step 201 in FIG. 9C). As a result, as shown in FIG. 3, the feed pump 1 and the supply pump 8 connected to a crankshaft (not shown) of the engine 2 operate.

When the feed pump 1 operates, the fuel in the fuel tank 5 is sucked into the suction port 1b of the feed pump 1 through the supply path 10a, the prefilter 6, and the supply path 10b. The feed pump 1 boosts the fuel to a fuel pressure of 3 kgf / cm 2 and discharges the fuel from the discharge port 1a to the supply path 10c. The fuel boosted by the feed pump 1 is sucked into the supply pump 8 through the supply path 10c, the main filter 7, and the supply path 10d.

If the controller 50 determines that the regeneration time is reached based on the detection signal from the sensor 51 (YES in step 203 in FIG. 9C), the exhaust pipe is connected via the output 50c of the controller 50. A signal for commanding fuel supply into 4 is generated. As a result, an electrical command signal is output from the output section 50c of the controller 50 to the valves 17 and 19, the valves 17 and 19 are opened, the valve 18 is closed, and the relay section 13 is connected to the relay 13 from the output section 50c of the controller 50. On the other hand, an electrical command signal for energizing the relay 13 is output. As a result, the relay 13 is energized (step 205 in FIG. 9C). The dual-purpose pump 60 is activated by energizing the relay 13. Thus, the dual-purpose pump 60 operates while the engine 2 is operating. When the dual-purpose pump 60 operates, the fuel in the fuel tank 5 is sucked into the suction port 60b of the dual-purpose pump 60 through the supply path 10a, the prefilter 6, the supply path 10b, and the suction fuel supply path 30.

The dual-purpose pump 60 boosts the fuel to a fuel pressure of 7 kgf / cm 2 suitable for supply into the exhaust pipe 4 and discharges the fuel from the discharge port 60a to the supply path 20a. The fuel boosted by the dual-purpose pump 60 is injected and supplied into the exhaust pipe 4 through the supply passage 20a, the second on-off valve 17, the flow rate control valve 19, the supply passage 20b, and the nozzle 21. The opening of the flow rate control valve 19 is on / off controlled so as to obtain a flow rate required for HC dosing, and supplies a required flow rate of fuel to the nozzle 21. As a result, reproduction is performed (step 206 in FIG. 9C). The third on-off valve 18 is changed from the closed state to the open state at the end of the HC dosing so that the pressure in the fuel supply path 20b between the third on-off valve 18 and the flow rate control valve 19 is reduced to atmospheric pressure. To work.

The discharge pressure 7 kgf / cm 2 of the dual-purpose pump 60 also acts on the inlet 71 b of the first on-off valve 71 on the air vent fuel supply passage 70.

On the other hand, it is the regeneration time (YES in step 203 in FIG. 9C), and since the second on-off valve 17 is opened, the supply path 20b of the outlet 17a of the second on-off valve 17 is also used as a dual purpose. The discharge pressure of the pump 60 is 7 kgf / cm2. Since the supply path 20b of the outlet 17a of the second on-off valve 17 communicates with the outlet 71a of the first on-off valve 71 via the fuel pressure signal path 72, the outlet 71a of the first on-off valve 71 is a dual-purpose pump. The discharge pressure is 60 kgf / cm2.

Thus, the pressure acting on the inlet 71b of the first on-off valve 71 is the discharge pressure 7 kgf / cm 2 of the dual-purpose pump 60. Similarly, on the outlet 71a side, the discharge pressure 7 kgf / cm 2 of the dual-purpose pump 60 is increased to the cracking pressure ( Since 9 kgf / cm @ 2 plus 2 kgf / cm @ 2) is acting, the first on-off valve 71 is closed. The first on-off valve 71 is closed, whereby the air vent fuel supply passage 70 is closed. For this reason, the fuel discharged from the dual-purpose pump 60 is prevented from being supplied to the main filter 7 of the cylinder fuel supply passage 10 through the air vent fuel supply passage 70.

Here, when the supply of fuel into the exhaust pipe 4 is started, the fuel pressure in the supply passage 20a on the discharge port 60a side of the dual-purpose pump 60 may become very high. For example, the second on-off valve 17 may open before the opening of the flow control valve 19 is opened. At this time, the fuel pressure in the supply passage 20a on the discharge port 60a side of the dual-purpose pump 60 becomes very high. In this way, when the fuel pressure in the supply passage 20a on the discharge port 60a side of the dual-purpose pump 60 is very high at the time of starting the supply of fuel into the exhaust pipe 4, the discharge port 60a of the dual-purpose pump 60 is greatly increased. The fuel pressure on the side reaches a predetermined relief pressure, and the fuel on the discharge port 60a side of the dual-purpose pump 60 is relieved from the relief valve 180 to the suction port 60b side of the dual-purpose pump 60. Thereby, the increase in the fuel pressure on the discharge port 60a side of the dual-purpose pump 60 can be suppressed. As a result, the durability of the dual-purpose pump 60 is improved. Further, since the fuel is returned to the suction port 60b side of the dual-purpose pump 60, there is an advantage that the clean fuel that has passed through the prefilter 6 can be reused.

Although the fuel is relieved from the relief valve 180 to the suction port 60b side of the dual-purpose pump 60, the fuel may be relieved from the relief valve 180 to the fuel tank 5. When the fuel is relieved from the relief valve 180 to the suction port 60b side of the dual-purpose pump 60, if the fuel contains air, the fuel containing the air will flow between the suction port 60b and the discharge port 60a of the dual-purpose pump 60. There is a possibility that the fuel will not be sucked well when the dual-purpose pump 60 is operated. If the fuel is relieved from the relief valve 180 to the fuel tank 5, the fuel containing air can be discharged into the fuel tank 5 and the fuel can be sucked in well.

  As described above, when the engine 2 is operating, HC dosing is performed and regeneration is performed.

As described above, according to this embodiment, the dual-purpose pump 60 can be used to release air from the in-cylinder fuel supply passage 10 and to supply fuel into the exhaust pipe 4, thereby reducing the apparatus cost. can do. Moreover, it can avoid that the fuel pressure of the exit side of the combined use pump 60 becomes high pressure, and the reliability of the combined use pump 60 increases.

1, 2, and 3, the first opening / closing valve 71 is assumed to be opened / closed by a fuel pressure signal. However, the first opening / closing valve 71 is opened / closed by an electric signal. Implementation is also possible.

FIG. 4 is a diagram corresponding to FIGS. 1A to 3, and shows an embodiment in which the first on-off valve 71 is configured by an electromagnetic valve that opens and closes when an electrical command signal is applied. In FIG. 4, the flow of fuel during HC dosing is indicated by black arrows.

(Operation when bleeding air in Fig. 4)
That is, when the switch 12 is turned on at the time of “air bleeding”, a signal is generated by the switch 12 to command air removal from the in-cylinder fuel supply passage 10. In addition to the first on-off valve 71, the first on-off valve 71 is opened. Further, since the controller 50 does not generate a signal for commanding fuel supply into the exhaust pipe 4, the second on-off valve 17 is closed. For this reason, as in FIG. 1A, HC dosing is not performed, and air removal from the cylinder fuel supply passage 10 is performed.

(Operation when neither air bleeding nor HC dosing in FIG. 4 is performed)
In addition, when the engine is operating without air bleeding or HC dosing, the switch 12 is turned off, and no signal is generated to command air removal from the in-cylinder fuel supply passage 10. Since the signal is not applied to the first on-off valve 71, the first on-off valve 71 is closed. Further, since the controller 50 does not generate a signal for commanding fuel supply into the exhaust pipe 4, the second on-off valve 17 is closed. Therefore, neither air bleeding nor HC dosing is performed as in FIG.

(Operation during HC dosing in FIG. 4)
At the time of “HC dosing”, the switch 12 is turned off, and a signal for commanding air removal from the in-cylinder fuel supply passage 10 is not generated. This signal is applied to the first on-off valve 71 as an electric command signal. Therefore, the first on-off valve 71 is closed. Further, the controller 50 generates a signal for instructing fuel supply into the exhaust pipe 4, and this signal is applied as an electrical command signal to the second on-off valve 17, so that the second on-off valve 17 is opened. Therefore, as in FIG. 3, HC dosing is performed and fuel is supplied into the exhaust pipe 4.

In the apparatus shown in FIG. 1, the fuel pump is uniformly sucked into the dual-purpose pump 60 from the supply passage 10b on the suction port 1b side of the feed pump 1, but the engine 2 is in operation and performs HC dosing. In some cases, the dual-purpose pump 60 may be configured as a small-sized pump having a small boosting capability by allowing the dual-purpose pump 60 to suck fuel from the supply passage 10c on the discharge port 1a side of the feed pump 1.

FIG. 5 shows that when the engine 2 is not in operation and the air is vented, the dual-purpose pump 60 sucks the fuel into the supply passage 10b on the suction port 1b side of the feed pump 1, and the engine 2 is in operation and the HC dosing. In this embodiment, the dual-purpose pump 60 is configured to suck the fuel into the supply passage 10c on the discharge port 1a side of the feed pump 1.

In the following, the same constituent elements as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted as appropriate.

In the embodiment apparatus shown in FIG. 5, the supply passage 10 b on the suction port 1 b side of the feed pump 1 and the suction port 60 b of the dual-purpose pump 60 in the in-cylinder fuel supply passage 10 are defined by the first suction fuel supply passage 80. It is communicated.

  Further, the supply passage 10 c on the discharge port 1 a side of the feed pump 1 in the in-cylinder fuel supply passage 10 and the suction port 60 b of the dual-purpose pump 60 are communicated with each other by a second suction fuel supply passage 81.

On the first suction fuel supply passage 80, a first suction on-off valve 82 that opens and closes the first suction fuel supply passage 80 is provided. The first suction opening / closing valve 82 is constituted by a check valve, and allows only a flow in the direction from the supply passage 10b on the suction port 1b side of the feed pump 1 to the suction port 60b of the dual-purpose pump 60.

On the second suction fuel supply passage 81, a second suction on-off valve 83 that opens and closes the second suction fuel supply passage 81 is provided. The second suction on-off valve 83 is constituted by a pilot check valve, and allows only the flow in the direction from the supply passage 10 c on the discharge port 1 a side of the feed pump 1 to the suction port 60 b of the dual-purpose pump 60.

(Operation when bleeding air; Fig. 5)
The operator turns on the switch 12 in order to release air before the engine 2 is started and when the engine 2 is not in operation.

When the switch 12 is turned on, a signal for commanding air removal from the in-cylinder fuel supply passage 10 is generated and the relay 13 is energized. The dual-purpose pump 60 is activated by energizing the relay 13.

  On the other hand, since the engine 2 is not operating, the feed pump 1 is not operating, fuel is not discharged from the discharge port 1a of the feed pump 1, and the pressure of the supply passage 10c on the discharge port 1a side is atmospheric pressure. The inlet 83b of the second suction on-off valve 83 is at atmospheric pressure. On the other hand, the pressure of the supply passage 10b on the suction port 1b side of the feed pump 1 is atmospheric pressure, and the inlet 82b of the first suction opening / closing valve 82 is similarly atmospheric pressure.

  By the operation of the dual-purpose pump 60, the fuel in the fuel tank 5 is transferred from the supply passage 10b on the suction port 1b side of the feed pump 1 to the suction port 60b of the dual-purpose pump 60 via the first suction fuel supply passage 80. Sucked. The dual-purpose pump 60 boosts the atmospheric pressure fuel to 4 kgf / cm 2 and discharges it to the air vent fuel supply passage 70. The fuel that has passed through the outlet 82a of the first suction opening / closing valve 82 is blocked by the second suction opening / closing valve 83 and is prevented from flowing into the supply passage 10c on the discharge port 1a side of the feed pump 1. The

Thus, when a signal for commanding air removal from the cylinder fuel supply passage 10 is generated, the first suction on-off valve 82 is opened, and the second suction on-off valve 83 is closed, Fuel is sucked into the suction port 60 b of the dual-purpose pump 60 from the suction port 1 b side of the feed pump 1 through the first suction fuel supply path 80. Other operations are the same as those in FIG. 1, and air bleeding is performed.

(Operation when the engine is running without air bleeding or HC dosing; Fig. 6)
When the operator turns on an engine start key switch (not shown), the engine 2 is started and the engine 2 is operated. As a result, as shown in FIG. 6, the feed pump 1 and the supply pump 8 connected to a crankshaft (not shown) of the engine 2 are operated.

When the feed pump 1 operates, the fuel in the fuel tank 5 is sucked into the suction port 1b of the feed pump 1 through the supply path 10a, the prefilter 6, and the supply path 10b. The feed pump 1 boosts the fuel to a fuel pressure of 3 kgf / cm 2 and discharges the fuel from the discharge port 1a to the supply path 10c. The fuel boosted by the feed pump 1 is sucked into the supply pump 8 through the supply path 10c, the main filter 7, and the supply path 10d.

When the controller 50 determines that the regeneration time has not come based on the detection signal of the sensor 51, the controller 50 does not generate a signal for instructing fuel supply into the exhaust pipe 4. For this reason, the electrical command signal from the controller 50 to each of the valves 17, 18, and 19 is turned off, the valves 17, 18, and 19 are closed, and the relay 13 that is supplied from the controller 50 to the relay 13 is turned on. The electrical command signal for energizing is turned off.

When the air is not vented from the cylinder fuel supply passage 10, the switch 12 is turned off. When the switch 12 is off, no signal for commanding air removal from the cylinder fuel supply passage 10 is generated, and the electrical command signal for energizing the relay 13 is off.

As described above, the electrical command signal for energizing the relay 13 is not applied to the relay 13, and the relay 13 is de-energized. As a result, the dual-purpose pump 60 does not operate.

When the feed pump 1 is operated, fuel is discharged from the discharge port 1 a of the feed pump 1, and the fuel pressure in the supply passage 10 c on the discharge port 1 a side becomes 3 kgf / cm 2, and this fuel pressure is the inlet 83 b of the second suction on-off valve 83. Added to the side. On the other hand, the pressure in the supply passage 10b on the suction port 1b side of the feed pump 1 is negative, and the inlet 82b of the first suction on-off valve 82 is similarly negative.

For this reason, the first suction on-off valve 82 is closed and the second suction on-off valve 83 is opened. However, since the dual-purpose pump 60 is not in operation, there is no flow toward the suction port 60b of the dual-purpose pump 60 through the second suction on-off valve 83.

(Operation during HC dosing; Fig. 7)
When the operator turns on an engine start key switch (not shown), the engine 2 is started and the engine 2 is operated. As a result, as shown in FIG. 7, the feed pump 1 and the supply pump 8 connected to a crankshaft (not shown) of the engine 2 operate.

When the controller 50 determines that the regeneration time has come based on the detection signal of the sensor 51, the controller 50 generates a signal for instructing fuel supply into the exhaust pipe 4. As a result, an electrical command signal is output from the controller 50 to the valves 17 and 19, the valves 17 and 19 are opened, the valve 18 is closed, and the relay 13 is energized from the controller 50 to the relay 13. An electrical command signal is output for this purpose. As a result, the relay 13 is energized. The dual-purpose pump 60 is activated by energizing the relay 13. Thus, the dual-purpose pump 60 operates while the engine 2 is operating.

When the feed pump 1 is operated, fuel is discharged from the discharge port 1 a of the feed pump 1, and the fuel pressure in the supply passage 10 c on the discharge port 1 a side becomes 3 kgf / cm 2, and this fuel pressure is the inlet 83 b of the second suction on-off valve 83. Added to the side. On the other hand, the pressure in the supply passage 10b on the suction port 1b side of the feed pump 1 is negative, and the inlet 82b of the first suction on-off valve 82 is similarly negative. For this reason, the first suction on-off valve 82 is closed, the second suction on-off valve 83 is opened, and the fuel pressurized to 3 kgf / cm 2 is supplied from the supply passage 10 c on the discharge port 1 a side of the feed pump 1. Then, the air is sucked into the suction port 60 b of the dual-purpose pump 60 through the second suction fuel supply passage 81. The dual-purpose pump 60 further boosts the fuel whose pressure has been increased to 3 kgf / cm 2 to 7 kgf / cm 2 and discharges it to the fuel supply passage 20 in the exhaust pipe. Note that the inlet 82b of the first suction on-off valve 82 has a negative pressure, and a high pressure (3 kgf / cm 2) acts on the outlet 82a of the first suction on-off valve 82, so that the first suction on-off valve 82 is used. Since the on-off valve 82 is closed, the fuel passes through the first suction on-off valve 82 and is sucked into the combined pump 60, or the fuel that has passed through the second suction on-off valve 83 is used for the first suction. It does not flow through the on-off valve 82 into the supply passage 10b on the suction port 1b side of the feed pump 1.

Thus, when a signal for commanding fuel supply into the exhaust pipe 4 is generated, the second suction on-off valve 83 is opened, and the first suction on-off valve 82 is closed. The fuel is sucked into the suction port 60 b of the dual-purpose pump 60 from the discharge port 1 a side of the feed pump 1 through the second suction fuel supply path 81. Other operations are the same as those in FIG. 3, and HC dosing is performed.

As described above, according to the embodiments shown in FIGS. 5, 6, and 7, when fuel is supplied into the exhaust pipe 4, fuel is sucked into the dual-purpose pump 60 from the discharge port 1 a side of the feed pump 1. Thus, the fuel is boosted to a fuel pressure of 7 kgf / cm 2 suitable for supplying the fuel into the exhaust pipe 4.

When the fuel is supplied into the exhaust pipe 4, the engine 2 is operating and the feed pump 1 is operating. The dual-purpose pump 60 may increase the fuel pressure already increased to about 3 kgf / cm 2 by the feed pump 1 to about 7 kgf / cm 2 suitable for supplying the fuel into the exhaust pipe 4. Compared with the case of boosting the fuel that is not, the dual pump 60 has a lower boosting capability.

On the other hand, air removal from the cylinder fuel supply passage 10 is performed mainly when the engine 2 is not in operation. According to this embodiment, when the air in the cylinder fuel supply passage 10 is vented, the fuel in the fuel tank 5 is sucked into the dual-purpose pump 60 from the suction port 1b side of the feed pump 1, so that the engine 2 is not operated. Even when the feed pump 1 is not operating, the fuel can be satisfactorily sucked from the fuel tank 5 on the suction 1b side of the feed pump 1. However, the fuel pressure 4 kgf / cm 2 when the fuel (atmospheric pressure) in the fuel tank 5 is boosted by the dual-purpose pump 60 is obtained by further boosting the fuel that has already been boosted to the predetermined pressure 3 kgf / cm 2 by the operation of the feed pump 1. Although the fuel pressure is lower than 7 kgf / cm 2 at the time, the air in the cylinder fuel supply passage 10 is originally required to be lower than that in the fuel supply into the exhaust pipe 4. Unplugging can be performed sufficiently.

According to this embodiment, the boosting capability of the dual-purpose pump 60 can be kept low, and the dual-purpose pump 60 can be downsized.

5, 6, and 7, the first suction on-off valve 82 and the second suction on-off valve 83 have been described on the assumption that they are configured as check valves. 82, the second suction on-off valve 83 may be configured as a valve that opens and closes by an electric signal.

FIG. 8 is a diagram corresponding to FIGS. 1A to 3, and an electrical command signal is applied to the first on-off valve 71, the first suction on-off valve 82, and the second suction on-off valve 83. The Example comprised with the solenoid valve which opens and closes is shown.

In FIG. 8, the fuel flow during HC dosing is indicated by black arrows.

(Operation when bleeding air in FIG. 8)
That is, at the time of “air bleeding”, when the switch 12 is turned on and a signal for commanding the air removal from the cylinder fuel supply passage 10 is generated by the switch 12, this command signal from the switch 12 becomes an electric command signal. The first suction on / off valve 82 is given to the first suction on / off valve 82 to open. Further, since the controller 50 does not generate a signal for instructing fuel supply into the exhaust pipe 4, the electrical command signal for the second suction on-off valve 83 is turned off and the second suction on-off valve 83 is closed. become. As a result, fuel is sucked into the suction port 60 b of the dual-purpose pump 60 from the suction port 1 b side of the feed pump 1 through the first suction fuel supply passage 80.

On the other hand, when the switch 12 is turned on and a signal for commanding the air removal from the cylinder fuel supply passage 10 is generated by the switch 12, the command signal is applied from the switch 12 to the first on-off valve 71 as an electrical command signal. Thus, the first on-off valve 71 is opened. Further, since the controller 50 does not generate a signal for instructing fuel supply into the exhaust pipe 4, the second on-off valve 17 is closed. Therefore, as in FIG. 5, HC dosing is not performed, but air removal from the in-cylinder fuel supply path 10 is performed.

(Operation when neither air bleeding nor HC dosing in FIG. 8 is performed)
In addition, when the engine is running with neither air venting nor HC dosing being performed, the switch 12 is turned off, so that a signal for commanding air venting of the in-cylinder fuel supply passage 10 is not generated, and the exhaust pipe 4 enters the exhaust pipe 4. Since the controller 50 does not generate a signal for instructing the fuel supply, the controller 50 closes the first suction on-off valve 82 and closes the second suction on-off valve 83.

On the other hand, a signal for commanding air removal from the cylinder fuel supply passage 10 is not generated, and this signal is not applied to the first on-off valve 71 as an electric command signal, so that the first on-off valve 71 is closed. Further, since the controller 50 does not generate a signal for commanding fuel supply into the exhaust pipe 4, the second on-off valve 17 is closed. Therefore, neither air bleeding nor HC dosing is performed as in FIG.

(Operation during HC dosing in FIG. 8)
During “HC dosing”, since the switch 12 is off, a signal for commanding air removal from the in-cylinder fuel supply passage 10 is not generated, and the electrical command signal for the first suction on-off valve 82 is turned off. Therefore, the first suction on-off valve 82 is closed. Further, since the controller 50 generates a signal for instructing fuel supply into the exhaust pipe 4, an electric command signal is given to the second suction opening / closing valve 83, and the second suction opening / closing valve 83 is Opened. As a result, high fuel pressure fuel is sucked into the suction port 60 b of the dual-purpose pump 60 from the discharge port 1 a side of the feed pump 1 through the second suction fuel supply path 81.

On the other hand, since the switch 12 is turned off, a signal for commanding air removal from the cylinder fuel supply passage 10 is not generated, and this signal is not applied to the first on-off valve 71 as an electric command signal. The on-off valve 71 is closed. Further, a signal for instructing fuel supply into the exhaust pipe 4 is generated by the controller 50, and this signal is applied as an electric command signal to the second on-off valve 17 to open the second on-off valve 17. Therefore, as in FIG. 7, HC dosing is performed, and fuel is supplied into the exhaust pipe 4.

In the above embodiment, the first on-off valve 71 is provided on the air vent fuel supply passage 70 to control the opening / closing of the first on-off valve 71. In addition, it is possible to implement a similar function by providing a diaphragm 171. When the throttle 171 is provided, unlike the case where the first opening / closing valve 71 is provided, the opening / closing control by the controller 50 and the fuel pressure signal path 72 (or electric signal line) are not required. For this reason, the system which also serves as a pump can be made into a simple structure, and an apparatus cost can be reduced further.

FIG. 10 is a diagram corresponding to FIGS. 1A to 3, and the fuel flow during HC dosing is indicated by black arrows. “Operation when bleeding”, “operation when neither bleeding nor HC dosing” and “operation when HC dosing” are shown in FIG. Since it is the same as that described with reference to FIGS. Accordingly, the process of step 103 is omitted in the flowchart of FIG.

However, when the throttle 171 is provided, unlike the case where the first on-off valve 71 is provided, there is a characteristic that the diaphragm 171 is always open. The effect will be described.

As shown in FIG. 10, a throttle 171 is provided on the air bleeding fuel supply path 70. In FIG. 10, the diaphragm 171 uses a fixed diaphragm.

The aperture area of the diaphragm 171 is preferably determined in consideration of the following points.

a) A sufficient amount of fuel is supplied from the dual-purpose pump 60 toward the in-cylinder fuel supply passage 10 toward the cylinder fuel supply passage 10. b) Considering the durability of the dual-use pump 60. To do. That is, when the fuel supply into the exhaust pipe 4 is started, the fuel pressure in the supply path 20a that connects the discharge port 60a of the dual-purpose pump 60 and the second on-off valve 17 in the fuel supply path 20 in the exhaust pipe 4 is reduced. Even in the case where the fuel pressure increases, the fuel in the supply passage 20a flows into the in-cylinder fuel supply passage 10 via the throttle 171 to suppress an increase in the fuel pressure in the supply passage 20a.

c) Considering the performance of the nozzle 21, it is possible to pump fuel of a necessary and sufficient pressure to the nozzle 21. That is, when fuel is supplied into the exhaust pipe 4, some fuel may flow into the cylinder fuel supply path 10 via the throttle 171, and the fuel pressure in the exhaust pipe fuel supply path 20 may be somewhat lowered. Even so, the necessary and sufficient pressure should be fed to the nozzle 21 so that the fuel can be sprayed well so that the atomized fuel can be supplied to the exhaust pipe 4.

A check valve 172 is provided at the discharge port 60 a of the dual-purpose pump 60. The check valve 172 is disposed so as to prevent the flow of fuel from the air vent fuel supply path 70 to the intake fuel supply path 30 via the dual-purpose pump 60.

Note that the check valve 172 is not limited to the discharge port 60 a of the dual-purpose pump 60, and can be disposed at any location of the air bleeding fuel supply path 70, the dual-purpose pump 60, or the suction fuel supply path 30.

(Operation when bleeding air)
When the dual-purpose pump 60 is activated, the fuel with a fuel pressure of 7 kgf / cm 2 discharged from the dual-purpose pump 60 passes through the throttle 171 on the air vent fuel supply passage 70 (step 102 in FIG. 9B).

The fuel pressurized by the dual-purpose pump 60 is pumped to the main filter 7 via the throttle 171 of the air venting fuel supply passage 70, passes through the supply pump 8, and is discharged to the fuel tank 5 via the overflow fuel discharge passage 11. Is done. The fuel boosted by the dual-purpose pump 60 is pumped to the main filter 7 through the throttle 171 of the air venting fuel supply passage 70 and discharged to the fuel tank 5 through the air venting fuel discharge passage 32. Here, since the opening area of the throttle 171 is determined in consideration of the above point a), the air in the cylinder fuel supply path 10 is vented from the dual-purpose pump 60 toward the cylinder fuel supply path 10 side. Therefore, a necessary and sufficient amount of fuel is supplied. As a result, air is extracted from the cylinder fuel supply passage 10 (step 104 in FIG. 9B).

(Operation when the engine is running without air bleeding or HC dosing)
During the operation of the engine 2, fuel may flow into the air bleeding fuel supply path 70 from the in-cylinder fuel supply path 10 through the throttle 171. In contrast, since the check valve 172 is provided, the check valve 172 prevents the flow of fuel from the air bleeding fuel supply path 70 to the intake fuel supply path 30 via the dual-purpose pump 60. As a result, while the engine 2 is in operation, the fuel passes through the throttle 171 on the air venting fuel supply passage 70 and passes through the dual-purpose pump 60 and the suction fuel supply passage 30 to the cylinder fuel supply passage 10. Reflux can be prevented. An on-off valve is provided in place of the check valve 172, and the on-off valve is closed when necessary so that the flow of fuel from the air bleeding fuel supply path 70 to the intake fuel supply path 30 via the dual-purpose pump 60 is reduced. You may make it stop.

Here, if the main filter 7 in the in-cylinder fuel supply passage 10 is clogged during operation of the engine 2, the fuel pressure on the discharge port 60a side of the dual-purpose pump 60 communicating with the throttle 171 may become very high. In this way, when the fuel pressure on the discharge port 60a side of the dual-purpose pump 60 is very high during the operation of the engine 2, the fuel pressure on the discharge port 60a side of the dual-purpose pump 60 reaches a predetermined relief pressure, and the relief valve 180 The fuel on the discharge port 60a side of the dual-purpose pump 60 is relieved to the suction port 60b side of the dual-purpose pump 60. Thereby, the increase in the fuel pressure on the discharge port 60a side of the dual-purpose pump 60 can be suppressed. As a result, the durability of the dual-purpose pump 60 is improved.

The fuel is relieved from the relief valve 180 to the suction port 60b side of the dual-purpose pump 60. In order to cope with the case where air is contained in the fuel, the fuel is removed from the relief valve 180 to the fuel tank. 5 may be reliefd.

  As described above, according to the present embodiment in which the throttle 171 is provided, the cost of the apparatus can be reduced to the same as or more than that in the embodiment in which the first on-off valve 71 is provided, and the main filter 7 is also used due to clogging. The reliability of the dual-purpose pump 60 can be improved by avoiding a high fuel pressure on the outlet side of the pump 60.

(Operation during HC dosing)
While the fuel is supplied to the exhaust pipe 4 via the dual-purpose pump 60, the fuel with the discharge pressure of 7 kgf / cm 2 from the dual-purpose pump 60 is also supplied to the throttle 171 on the air bleeding fuel supply path 70. Here, the opening area of the diaphragm 171 is determined in consideration of the point b). That is, when the fuel supply into the exhaust pipe 4 is started, the fuel pressure in the supply passage 20a may increase greatly exceeding 7 kgf / cm2. For example, the second on-off valve 17 may open before the opening of the flow control valve 19 is opened. At this time, the fuel pressure in the supply passage 20a on the discharge port 60a side of the dual-purpose pump 60 becomes very high. As described above, even when the fuel pressure in the supply passage 20a increases greatly exceeding 7 kgf / cm 2 at the start of the supply of fuel into the exhaust pipe 4 or the like, in this embodiment, in the supply passage 20a. Since the fuel flows into the in-cylinder fuel supply path 10 via the throttle 171, an increase in the fuel pressure in the supply path 20 a can be suppressed. Thereby, the durability of the dual-purpose pump 60 is improved.

In addition, since the opening area of the throttle 171 is determined in consideration of the above point c), when fuel is supplied into the exhaust pipe 4, some fuel is supplied to the cylinder fuel supply passage 10 via the throttle 171. Even if the fuel pressure in the exhaust pipe fuel supply passage 20 is somewhat lowered, a necessary and sufficient pressure is pumped to the nozzle 21 so that the fuel is sprayed well, and the atomized state is maintained. Fuel can be supplied to the exhaust pipe 4.

As described above, according to the present embodiment, even when the fuel pressure in the supply passage 20a of the exhaust pipe fuel supply passage 20 is increased, for example, when fuel supply into the exhaust pipe 4 is started, Since the fuel in the supply path 20a flows into the in-cylinder fuel supply path 10 via the restrictor 171, an increase in the fuel pressure in the supply path 20a can be suppressed. Thereby, the durability of the dual-purpose pump 60 can be improved.

In the embodiment shown in FIG. 10, the case where the diaphragm 171 is configured with a fixed diaphragm has been described. However, the diaphragm 171 may be configured with a variable diaphragm.

FIG. 11 shows an embodiment in which the diaphragm 171 in FIG. 10 is configured with a variable diaphragm. In FIG. 11, the fuel flow at the time of HC dosing is shown by black arrows.

However, unlike the fixed diaphragm, the opening area of the variable diaphragm 171 can be optimally adjusted according to each operation. For example, when air bleeding is desired to be performed quickly, adjustment can be made so that the opening area of the variable throttle 171 is increased only during air bleeding.

  In the present embodiment in which the throttle 171 is provided, various modifications can be made as in the embodiment in which the first on-off valve 71 is provided.

FIG. 12 is a diagram corresponding to FIG. 5, except that a throttle 171 is provided instead of the first on-off valve 71, the fuel pressure signal path 72 is eliminated, and the opening / closing control by the controller 50 is not required. 6 and 7 are the same in configuration and operation, and similarly, the first suction on-off valve 82 and the second suction on-off valve 83 are controlled by the fuel pressure signal, and the dual pump 60 has a small boosting capability. It can be. However, the specific operation by the diaphragm 171 is the same as that described with reference to FIG.

FIG. 13 is a diagram corresponding to FIG. 8, except that a throttle 171 is provided instead of the first on-off valve 71 to eliminate the corresponding electric signal line and the control of the opening / closing by the controller 50 is unnecessary. 8, the first suction on-off valve 82 and the second suction on-off valve 83 are controlled by an electrical command signal, and the dual-purpose pump 60 has a small boosting capability. it can. However, the specific operation by the diaphragm 171 is the same as that described with reference to FIG.
As described above, in the present embodiment, the dual-purpose pump that serves both as the air vent of the in-cylinder fuel supply passage and the fuel supply into the exhaust pipe, and at the time of air venting, while preventing the fuel supply from the dual-purpose pump into the exhaust pipe, When the fuel is supplied from the dual-purpose pump to the cylinder fuel supply passage and fuel is supplied to the exhaust pipe, the fuel supply from the dual-purpose pump to the cylinder fuel supply passage is blocked or suppressed while When the discharge pressure of the dual-purpose pump reaches a predetermined relief pressure, the fuel on the discharge port side of the dual-purpose pump is lower than the discharge pressure of the dual-purpose pump (for example, the suction of the dual-purpose pump). A relief valve for relief on the mouth side or the fuel tank). Therefore, the combined use of the pump can reduce the cost of the apparatus, and the reliability of the dual-purpose pump can be improved by avoiding the fuel pressure on the outlet side of the dual-purpose pump becoming high.

  In the embodiment, the case where the fuel is supplied to the exhaust pipe 4 in order to regenerate the exhaust gas aftertreatment device such as the diesel particulate filter 14 has been described. The present invention is not limited, and can be applied when fuel is supplied to an exhaust gas aftertreatment device provided in the exhaust pipe 4 for an arbitrary purpose. For example, the exhaust pipe 4 is provided with a catalyst for removing NOx in the exhaust gas, and in order to increase the NOx removal rate by this catalyst, light oil fuel as a reducing agent for the catalyst is injected and supplied to the exhaust pipe in a high pressure state. In this case, the present invention may be applied.

  Although not shown, in order to protect the second on-off valve 17 by suppressing the high fuel pressure from being applied to the inlet of the second on-off valve 17, the second on-off valve 17 in the supply passage 20a is protected. A diaphragm may be arranged in the vicinity of the entrance.

  DESCRIPTION OF SYMBOLS 100 Engine fuel supply apparatus 100, 1 Fuel pump (feed pump), 2 engine, 10 In-cylinder fuel supply path 10, 4 Exhaust pipe, 20 Exhaust pipe fuel supply path, 60 Combined pump, 70 Air vent fuel supply path , 71 1st on-off valve, 171 throttle, 172 Check valve, 180 relief valve, 17 2nd on-off valve, 50 controller, 51 sensor, 72 Fuel pressure signal path

Claims (12)

A fuel supply device for an engine provided with an in-cylinder fuel supply path for supplying fuel into a cylinder of the engine via a fuel pump, and an exhaust pipe fuel supply path for supplying fuel into the exhaust pipe of the engine,
A dual-purpose pump that is provided separately from the fuel pump and serves both as an air vent for the cylinder fuel supply passage and a fuel supply to the exhaust pipe;
An air venting fuel supply path that communicates the discharge port of the dual-purpose pump and the fuel supply path in the cylinder;
An exhaust pipe fuel supply passage communicating the discharge port of the dual-purpose pump and the exhaust pipe;
A first on-off valve provided on the air venting fuel supply path and opening and closing the air venting fuel supply path;
A second on-off valve provided on the fuel supply path in the exhaust pipe and opening and closing the fuel supply path in the exhaust pipe;
When a signal for commanding air removal from the cylinder fuel supply passage is generated, the dual-purpose pump is operated, the first on-off valve is opened, the second on-off valve is closed, and fuel is discharged from the dual-purpose pump. And supplying the cylinder fuel supply passage through the air vent fuel supply passage,
When a signal for commanding fuel supply into the exhaust pipe is generated, the dual-purpose pump is operated, the second on-off valve is opened, the first on-off valve is closed, and fuel is discharged from the dual-purpose pump. Control means for supplying to the exhaust pipe via the in-pipe fuel supply path;
When the fuel pressure on the discharge port side of the dual-purpose pump reaches the specified relief pressure, a relief valve is provided to relieve the fuel on the discharge port side of the dual-purpose pump to the suction port side of the dual-purpose pump or to the fuel tank. Engine fuel supply device. A fuel supply device for an engine provided with an in-cylinder fuel supply path for supplying fuel into a cylinder of the engine via a fuel pump, and an exhaust pipe fuel supply path for supplying fuel into the exhaust pipe of the engine,
A dual-purpose pump that is provided separately from the fuel pump and serves both as an air vent for the cylinder fuel supply passage and a fuel supply to the exhaust pipe;
An air venting fuel supply path that communicates the discharge port of the dual-purpose pump and the fuel supply path in the cylinder;
An exhaust pipe fuel supply passage communicating the discharge port of the dual-purpose pump and the exhaust pipe;
A throttle provided on the air supply fuel supply passage;
A first on-off valve provided on the fuel supply path in the exhaust pipe and opening and closing the fuel supply path in the exhaust pipe;
When a signal to command air removal from the in-cylinder fuel supply path is generated, the dual-purpose pump is operated, the first on-off valve is closed, fuel is discharged from the dual-purpose pump, and the throttle on the air supply fuel supply path is Through the cylinder fuel supply path,
When a signal for instructing fuel supply into the exhaust pipe is generated, the dual-purpose pump is operated, the first on-off valve is opened, and the fuel from the dual-purpose pump is supplied to the exhaust pipe through the exhaust pipe fuel supply passage. Control means for supplying to
When the fuel pressure on the discharge port side of the dual-purpose pump reaches the specified relief pressure, a relief valve is provided to relieve the fuel on the discharge port side of the dual-purpose pump to the suction port side of the dual-purpose pump or to the fuel tank. Engine fuel supply device. A first suction fuel supply path that communicates a supply path on the suction port side of the fuel pump and a suction port of the dual-purpose pump among the in-cylinder fuel supply path;
A second suction fuel supply path that communicates a supply path on the discharge port side of the fuel pump and a suction port of the dual-purpose pump among the fuel supply paths in the cylinder;
A first suction on-off valve provided on the first suction fuel supply path and opening and closing the first suction fuel supply path;
A second suction on-off valve provided on the second suction fuel supply path, which opens and closes the second suction fuel supply path;
When a signal to command air removal from the cylinder fuel supply passage is generated, the first suction on-off valve is opened, the second suction on-off valve is closed, and the fuel pump suction side From the first suction fuel supply passage to the fuel suction port of the dual-purpose pump,
When a signal for commanding fuel supply into the exhaust pipe is generated, the second suction on-off valve is opened, the first suction on-off valve is closed, and the fuel pump discharge port side 2. The fuel supply device for an engine according to claim 1, further comprising control means for sucking fuel into the suction port of the dual-purpose pump through two suction fuel supply passages. A first suction fuel supply path that communicates a supply path on the suction port side of the fuel pump and a suction port of the dual-purpose pump among the in-cylinder fuel supply path;
A second suction fuel supply path that communicates a supply path on the discharge port side of the fuel pump and a suction port of the dual-purpose pump among the fuel supply paths in the cylinder;
A first suction on-off valve provided on the first suction fuel supply path and opening and closing the first suction fuel supply path;
A second suction on-off valve provided on the second suction fuel supply path, which opens and closes the second suction fuel supply path;
When a signal to command air removal from the cylinder fuel supply passage is generated, the first suction on-off valve is opened, the second suction on-off valve is closed, and the fuel pump suction side From the first suction fuel supply passage to the fuel suction port of the dual-purpose pump,
When a signal for commanding fuel supply into the exhaust pipe is generated, the second suction on-off valve is opened, the first suction on-off valve is closed, and the fuel pump discharge port side 3. The engine fuel supply device according to claim 2, further comprising a control means for sucking fuel into a suction port of the dual-purpose pump through two suction fuel supply passages. The engine fuel supply device according to claim 1, wherein the first on-off valve is opened and closed by a fuel pressure signal. The engine fuel supply device according to claim 1, wherein the first on-off valve is opened and closed by an electric signal. The engine fuel supply device according to claim 3, wherein the first on-off valve, the first suction on-off valve, and the second suction on-off valve are opened and closed by an electric signal. The engine fuel supply device according to claim 2, wherein the throttle is a variable throttle. A suction fuel supply passage communicating with the suction port of the dual-purpose pump is provided,
Check valve or on-off valve that blocks the flow of fuel from the air venting fuel supply path to the suctioning fuel supply path via the dual-purpose pump in either the air venting fuel supply path or the dual-purpose pump or the suction fuel supply path The fuel supply device for an engine according to claim 1, wherein: The engine fuel supply device according to claim 4, wherein the first suction on-off valve and the second suction on-off valve are opened and closed by an electric signal. A dual-purpose pump that serves as both the air vent for the cylinder fuel supply passage and the fuel supply to the exhaust pipe;
At the time of air bleeding, the fuel is supplied from the dual-purpose pump to the cylinder fuel supply passage while preventing the fuel supply from the dual-purpose pump into the exhaust pipe.
Means for supplying fuel from the dual-purpose pump into the exhaust pipe while preventing or suppressing the supply of fuel from the dual-purpose pump to the cylinder fuel supply path when fuel is supplied to the exhaust pipe;
An engine comprising a relief valve that relieves the fuel on the discharge port side of the dual-purpose pump to a lower pressure side than the discharge pressure of the dual-purpose pump when the discharge pressure of the dual-purpose pump reaches a predetermined relief pressure. Fuel supply system. 12. The engine fuel supply device according to claim 11, wherein the pressure lower than the discharge pressure of the dual-purpose pump is a suction port side or a fuel tank of the dual-purpose pump.

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