JP2014098319A - Fuel supply device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel supply device enabled to change fuels that an injector injects.SOLUTION: An injector 30 injects and supplies a gaseous fuel supplied from a high-pressure fuel tank 11 and a liquid fuel supplied from a liquid fuel tank 12 to an engine 2. A fuel passage upstream from a valve seat that a valve body of the injector 30 is seated on and separated from and the liquid fuel tank 12 are linked to each other by a release passage 60. An ECU 70 opens a release valve 61 when a fuel in the fuel passage in the injector is discharged to the liquid fuel tank 12 and closes the release valve 61 when the injector 30 injects and supplies the fuel from a jet hole to the engine 2. A fuel supply device 1 can change the pressure of a gaseous fuel flowing in the fuel passage of the injector 30 and also can change the gaseous fuel and liquid fuel flowing in the fuel passage of the injector 30.

Description

  The present invention relates to a fuel supply device that supplies fuel to an engine that supports a plurality of types of fuel.

Conventionally, a fuel supply device that supplies fuel to a bi-fuel engine that can use two types of fuel or a multi-fuel engine that can use three or more types of fuel is known.
The fuel supply device described in Patent Literature 1 includes a first injector that injects gaseous fuel into an engine and a second injector that injects liquid fuel. When the engine is operating using gaseous fuel, the fuel supply device injects and supplies the liquid fuel to the engine when the temperature of the liquid fuel staying in the second injector is accelerated. Thereby, the fuel supply device suppresses the generation of vapor in the liquid fuel in the second injector.

JP 2006-138295 A

However, since the fuel supply device described in Patent Document 1 includes two injectors, a space for mounting the injectors is increased, the degree of freedom in engine design is restricted, and the manufacturing cost is increased.
Further, the fuel supply device described in Patent Document 1 injects and supplies the liquid fuel to the engine when the temperature of the liquid fuel staying in the second injector is promoted to vaporize. There is concern about the increase.
Furthermore, in the fuel supply device described in Patent Document 1, the pressure of the gaseous fuel supplied from the first injector to the engine is constant, and the gaseous fuel cannot be switched to a pressure adapted to the operating conditions of the engine.
The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel supply device that enables switching of fuel injected by an injector.

The present invention relates to a fuel supply apparatus including an injector for injecting a first fuel supplied from a high-pressure fuel tank, and a fuel passage for an injector and a low-pressure fuel tank that stores a second fuel at a pressure lower than an injection pressure of the first fuel. And the release passage communicates with each other.
Thus, the first fuel supplied to the injector is discharged to the low-pressure fuel tank through the release passage by opening the release valve. For this reason, the pressure of the 1st fuel injected from an injector can be switched.
In addition, if another type of fuel different from the first fuel is supplied to the injector, the fuel injected by the injector can be switched between the first fuel and the other type of fuel. Thus, a plurality of types of fuel can be injected into the engine with a single injector.
Furthermore, if the first fuel discharged to the liquid fuel tank is configured to be supplied to the engine, the consumption amount of the first fuel can be reduced.

1 is a system configuration diagram of a fuel supply device according to a first embodiment of the present invention. It is sectional drawing of the injector with which a fuel supply apparatus is provided. It is sectional drawing of the III-III line of FIG. FIG. 4 is an enlarged view of a portion IV in FIG. 2 and a cross-sectional view taken along line IV-IV in FIG. 3. It is a flowchart of the fuel switching process which a fuel supply apparatus performs. It is operation | movement explanatory drawing of the fuel switching process which a fuel supply apparatus performs. It is operation | movement explanatory drawing of the fuel switching process which a fuel supply apparatus performs. It is operation | movement explanatory drawing of the fuel switching process which a fuel supply apparatus performs. It is operation | movement explanatory drawing of the fuel switching process which a fuel supply apparatus performs. It is a system block diagram of the fuel supply apparatus by 2nd Embodiment of this invention. It is a flowchart of the pressure reduction switching process which a fuel supply apparatus performs.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
A first embodiment of the present invention is shown in FIGS. The fuel supply device 1 according to this embodiment is a two-fuel compatible fuel supply system that supplies fuel to a bi-fuel engine 2 that can use gaseous fuel and liquid fuel.
The engine 2 compresses the mixture of liquid fuel or gaseous fuel and air sucked into the cylinder from the intake passage 5 by reciprocating movement of the piston 4 provided inside the cylinder 3, and the mixture is ignited by the spark plug 6. Is ignited and burned, and exhaust gas is discharged from the exhaust passage 7.

As shown in FIG. 1, the fuel supply device 1 includes a high-pressure fuel tank 11, a liquid fuel tank 12, an injector 30, a release passage 60, an electronic control unit (ECU) 70 as a control means, and the like.
The high-pressure fuel tank 11 is a pressure vessel that stores gaseous fuel such as CNG (Compressed Natural Gas), LNG (Liquefied Natural Gas), or hydrogen. The high-pressure fuel tank 11 stores gaseous fuel at a high pressure (for example, 20 MPa). The gaseous fuel stored in the high-pressure fuel tank 11 is reduced in pressure to a predetermined pressure (for example, 0.3 to 1 MPa) required by the engine 2 by the regulator 15 via the shut-off valve 14 and then the intake air of the engine 2 from the injector 30. Injected into the passage 5.

  The liquid fuel tank 12 is a fuel tank that stores liquid fuel such as gasoline. The liquid fuel tank 12 stores liquid fuel at atmospheric pressure. The liquid fuel stored in the liquid fuel tank 12 is pumped up by the pump 13, raised to the required pressure of the engine 2, and then injected and supplied from the injector 30 to the intake passage 5 of the engine 2.

The liquid fuel tank 12 of the present embodiment corresponds to a “low pressure fuel tank” recited in the claims. That is, the pressure at which the liquid fuel tank 12 stores the liquid fuel is smaller than the injection pressure of the gaseous fuel injected from the injector 30 and the injection pressure of the liquid fuel.
In the present embodiment, the gaseous fuel corresponds to the “first fuel” recited in the claims, and the liquid fuel corresponds to the “second fuel” recited in the claims.

A cylinder fuel pipe 20 is connected to the high-pressure fuel tank 11 and the regulator 15, and a second fuel pipe 22 is connected to the regulator 15 and the fuel switching valve 16. Further, the second fuel pipe 22 is connected to the liquid fuel tank 12 and the fuel switching valve 16, and the third fuel pipe 23 is connected to the fuel switching valve 16 and the injector 30.
The fuel switching valve 16 communicates or shuts off the first fuel pipe 21 and the third fuel pipe 23, and communicates or shuts off the second fuel pipe 22 and the third fuel pipe 23 to supply gas to the injector 30. Switch between fuel and liquid fuel.

  The ECU 70 is provided with a signal E regarding the operating condition of the engine 2, a signal of the cylinder pressure sensor 71 provided in the cylinder fuel pipe 20, a signal of the fuel temperature / fuel pressure sensor 72 provided in the first fuel pipe 21, and a second fuel pipe 22. The fuel temperature / fuel pressure sensor 73 signal, the fuel temperature / fuel pressure sensor 74 signal provided in the release passage 60, and the like are input. Based on these signals, the ECU 70 drives and controls the cutoff valve 14, the regulator 15, the fuel switching valve 16, the injector 30, the release valve 61, the purge valve 83, and the like.

  When the fuel switching valve 16 communicates the first fuel pipe 21 and the third fuel pipe 23 and shuts off the second fuel pipe 22 and the third fuel pipe 23 according to a command from the ECU 70, the liquid fuel tank 12 and the injector 30. The fuel passage 31 is cut off, and the high-pressure fuel tank 11 and the fuel passage 31 of the injector 30 communicate with each other. Therefore, the gaseous fuel depressurized by the regulator 15 from the high-pressure fuel tank 11 through the cylinder fuel pipe 20 is supplied to the injector 30 through the first fuel pipe 21, the fuel switching valve 16, and the third fuel pipe 23.

  On the other hand, when the fuel switching valve 16 shuts off the first fuel pipe 21 and the third fuel pipe 23 and communicates the second fuel pipe 22 and the third fuel pipe 23 in accordance with a command from the ECU 70, the liquid fuel tank 12 The fuel passage 31 of the injector 30 communicates with the high pressure fuel tank 11 and the fuel passage 31 of the injector 30 is blocked. Therefore, the liquid fuel pumped up from the liquid fuel tank 12 by the pump 13 is supplied to the injector 30 through the second fuel pipe 22, the fuel switching valve 16 and the third fuel pipe 23.

  The fuel switching valve 16 may be integrated with the injector 30 or may be integrated with the regulator 15. If the fuel switching valve 16 and the injector 30 are configured integrally, the third fuel pipe 23 can be eliminated. If the fuel switching valve 16 and the regulator 15 are configured integrally, the first fuel pipe 21 can be eliminated. Thereby, the number of parts can be reduced and manufacturing cost can be reduced.

The injector 30 will be described with reference to FIGS.
The injector 30 includes a housing 32, an inlet member 33, a valve seat member 34, a movable nozzle 35, a valve body 36, a movable core 37, a fixed core 38, a release passage member 39, and the like.
The housing 32 is formed in a cylindrical shape, and has a first magnetic part 40, a nonmagnetic part 41, and a second magnetic part 42 from the top in FIG. The nonmagnetic part 41 prevents a short circuit of magnetic flux between the first magnetic part 40 and the second magnetic part 42.

An inlet member 33 is fixed to the end portion of the first magnetic portion 40 opposite to the nonmagnetic portion 41. Gas fuel and liquid fuel are supplied from the inlet member 33 to the inside of the housing 32.
The second magnetic part 42 has a large diameter part 421 and a small diameter part 422. A movable core 37 is accommodated inside the large diameter portion 421. A cylindrical stopper member 43 is fixed to the inside of the small diameter portion 422, and a bottomed cylindrical valve seat member 34 is fixed to the side opposite to the large diameter portion from the stopper member 43. The small diameter portion 422 has a communication hole 423 that communicates in the radial direction between the stopper member 43 and the valve seat member 34. The communication hole 423 communicates the fuel passage 31 inside the small diameter portion 422 and a fuel chamber 391 of a release passage member 39 described later.

The valve seat member 34 has a bottom portion 341 and a cylindrical portion 342 extending from the outer edge of the bottom portion 341 to the side opposite to the stopper member. The bottom portion 341 of the valve seat member 34 has a fuel hole 343 at the center thereof. An elastic portion 363 of a valve body 36 described later can be seated and separated on a valve seat 344 provided around the fuel hole 343 of the bottom portion 341.
A movable nozzle 35, a coil spring 44, and a ring member 45 are provided inside the tube portion 342 of the valve seat member 34. The movable nozzle 35 includes a flange portion 351 that can contact the bottom portion 341 of the valve seat member 34, and a nozzle portion 352 that extends from the flange portion 351 in a cylindrical shape. The flange portion 351 has a plurality of notches 353 on the outer diameter side. The nozzle portion 352 has a plurality of nozzle holes 354 at the tip thereof.
The ring member 45 is fixed to the opening end of the tubular portion 342 of the valve seat member 34. One end of the coil spring 44 abuts on the flange portion 351 of the movable nozzle 35 and the other end abuts on the ring member 45 to urge the movable nozzle 35 toward the bottom side of the valve seat member 34.

The valve body 36 includes a connecting portion 361 connected to the movable core 37, a valve body main body portion 362, and an elastic portion 363. The connecting portion 361 has a passage 364 through which fuel passes.
As shown in FIG. 3, the valve body main part 362 includes a guide part 365 and a notch part 366 that slide with the inner wall of the stopper member 43. Fuel can flow between the notch 366 and the stopper member 43.
As shown in FIG. 4, the valve body main body 362 has a contact surface 367 that can contact the tapered surface 431 of the stopper member 43. When the tapered surface 431 of the stopper member 43 and the contact surface 367 of the valve body main body 362 are in contact with each other, the movement of the valve body 36 in the valve closing direction is restricted.

  The elastic part 363 provided at the tip of the valve body main part 362 is made of, for example, a fluorine-based rubber having excellent low temperature resistance and oil resistance. When the gaseous fuel is injected from the nozzle hole 354, the pressure in the vicinity of the nozzle hole 354 decreases, and the temperature in the vicinity of the gas fuel may be about −30 ° C. to −40 ° C. The elastic portion 363 can be elastically deformed even in such a cryogenic environment, and ensures a sealing property with the valve seat 344.

When the liquid fuel is supplied from the inlet member 33 and the elastic portion 363 of the valve body 36 is separated from the valve seat 344, the flange portion 351 of the movable nozzle 35 is moved to the bottom portion 341 of the valve seat member 34 by the biasing force of the coil spring 44. It is in the state which contacted. At this time, the liquid fuel that has passed through the fuel hole 343 of the valve seat member 34 passes through the inside of the movable nozzle 35 and is injected from the injection hole 354.
On the other hand, when gaseous fuel is supplied from the inlet member 33 and the elastic portion 363 of the valve body 36 separates from the valve seat 344, the differential pressure between the inside and outside of the movable nozzle 35 increases, and the movable nozzle 35 The valve seat member 34 moves to the opposite side to the bottom 341 against the urging force of the coil spring 44. As a result, the flange portion 351 of the movable nozzle 35 and the bottom portion 341 of the valve seat member 34 are separated. Therefore, the gaseous fuel that has passed through the fuel hole 343 of the valve seat member 34 passes through the inside of the nozzle portion 352 and is injected from the injection hole 354, and also passes through the outside of the nozzle portion 352 from the notch 353 of the flange portion 351, thereby causing a ring member Injected from the gap between the nozzle 45 and the nozzle portion 352. Therefore, by providing the movable nozzle 35, the injector 30 can increase the volume when the gaseous fuel is injected, compared with the volume when the liquid fuel is injected.

The movable core 37 is formed in a cylindrical shape from a magnetic material, and is housed inside the nonmagnetic portion 41 and the second magnetic portion 42 so as to be capable of reciprocating in the axial direction.
The movable core 37 has a core main body 371 and a connecting portion 372 extending from the core main body 371 toward the valve seat member.
The core main body 371 of the movable core 37 has a guide portion 373 guided by the inner wall of the second magnetic portion 42 and the inner wall of the nonmagnetic portion 41.
The connecting portion 372 of the movable core 37 is fixed to the connecting portion 361 of the valve body 36. For this reason, the movable core 37 and the valve body 36 move integrally. The movable core 37 has a hole 374 communicating with the axial direction. The hole 374 of the movable core 37 and the passage 364 of the valve body 36 communicate with each other.

The fixed core 38 is formed in a cylindrical shape from a magnetic material, and is fixed to the inside of the nonmagnetic portion 41 and the first magnetic portion 40 on the inlet member side of the movable core 37. The fixed core 38 has an accommodation hole 381 that communicates in the axial direction. An adjusting pipe 46 and a spring 47 are provided inside the accommodation hole 381. The load of the spring 47 is set by adjusting the press-fitting amount of the adjusting pipe 46 into the accommodation hole 381. The adjusting pipe 46 has a hole 461 communicating with the axial direction.
One end of the spring 47 abuts on the adjusting pipe 46 and the other end abuts on the movable core 37 to urge the movable core 37 and the valve body 36 toward the valve seat member.

A coil 48 is wound around the outside of the housing 32 via an insulator (not shown). A cylindrical yoke 49 made of a magnetic material is provided outside the coil 48.
When the coil 48 is energized from the terminal 51 of the connector 50, the coil 48 is excited and magnetic flux is applied to the magnetic circuit formed by the yoke 49, the second magnetic part 42, the movable core 37, the fixed core 38, and the first magnetic part 40. Flows. Thereby, the movable core 37 is magnetically attracted to the fixed core side. For this reason, the elastic part 363 of the valve body 36 separates from the valve seat 344, and fuel is injected.
On the other hand, when the energization of the coil 48 is stopped, the magnetic flux of the magnetic circuit described above disappears, and the movable core 37 moves away from the fixed core 38 by the urging force of the spring 47 and moves to the valve seat member side. Thereby, the elastic part 363 of the valve body 36 is seated on the valve seat 344, and fuel injection stops.

A release passage member 39 is fixed to the outside of the small diameter portion 422 of the second magnetic portion 42. A release pipe 52 is connected to the release passage member 39.
The release passage member 39 has a disk shape, for example, and has a fuel chamber 391 that constitutes the release passage 60 inside. The fuel chamber 391 communicates with the fuel passage 31 between the stopper member 43 and the valve seat member 34 through the communication hole 423 of the small diameter portion 422. That is, the fuel chamber 391 of the release passage member 39 communicates with the fuel passage 31 immediately upstream of the valve seat 344.
The fuel chamber 391 communicates with a passage 521 formed inside the release pipe 52 through an outlet hole 392 provided in the release passage member 39.
That is, the release passage 60 includes the fuel chamber 391 of the release passage member 39, the outlet hole 392, and the passage 521 of the release pipe 52.
The release passage member 39, the release pipe 52, the yoke 49, the coil 48, and the housing 32 are integrally molded with a resin by a molded body 53.

As shown in FIGS. 1 and 4, the release passage 60 has one end communicating with the fuel passage 31 of the injector 30 and the other end communicating with the liquid fuel tank 12.
A release valve 61 is provided in the release passage 60. The release valve 61 is a flow path opening / closing valve, and opens or closes the release passage 60 according to a command from the ECU 70.

The fuel processing means 80 includes a purge passage 81 that connects the liquid fuel tank 12 and the intake passage 5 of the engine 2, a canister 82 provided in the purge passage 81, a purge valve 83, and the like. Inside the canister 82, an adsorbent (not shown) capable of adsorbing evaporated fuel and gaseous fuel evaporated from the liquid fuel is accommodated. The adsorbent is, for example, a carbon-based material such as activated carbon, zeolite, or aluminum phosphate.
The evaporated fuel evaporated from the liquid fuel in the liquid fuel tank and the gaseous fuel discharged from the release passage 60 to the liquid fuel tank 12 pass through the purge passage 81 and are adsorbed by the adsorbent in the canister 82.
When the purge valve 83 is opened by a command from the ECU 70, the evaporated fuel and the gaseous fuel adsorbed by the adsorbent are separated from the adsorbent and released into the intake passage 5 of the engine 2.

Next, the switching process between the gaseous fuel and the liquid fuel by the fuel supply apparatus 1 will be described with reference to the flowchart of FIG. 5 and the operation explanatory diagrams of FIGS. In the flowchart of FIG. 5, “step” is denoted as “S”.
This process starts when the ignition switch of the vehicle is turned on.
In step 1 of FIG. 5, the ECU 70 detects whether or not there is a “fuel injection switching instruction”. This instruction is for the ECU 70 to select fuel according to the operating conditions of the engine 2. Or fuel selection may be performed by a driver | operator's switch operation.
If there is no “fuel injection switching instruction”, the process proceeds to step 2. In step 2, the fuel is not switched, and the process proceeds to step 8, where the currently set gaseous fuel or liquid fuel is injected from the injector 30.

On the other hand, if there is a “fuel injection switching instruction” in step 1, the process proceeds to step 3.
In step 3, the ECU 70 detects whether or not the injector 30 is “injecting fuel”. “During fuel injection” refers to a period in which the valve body 36 of the injector 30 is separated from the valve seat 344 and fuel is being injected from the injector 30.
If “injecting fuel”, the process proceeds to step 4. In step 4, the fuel is not switched, and the process proceeds to step 8, and the currently set gaseous fuel or liquid fuel is injected from the injector 30.

On the other hand, if it is determined in step 3 that “fuel is not being injected”, the process proceeds to step 5.
Here, the case of “not injecting fuel” refers to a period in which the injector 30 does not inject fuel during operation of the engine 2 or a period in which the injector 30 stops fuel injection before starting the engine or after stopping the engine. Say. That is, the case of “not in fuel injection” is a period in which the elastic portion 363 of the valve body 36 of the injector 30 is seated on the valve seat 344, and refers to a period excluding fuel injection.

In the switching process between the gaseous fuel and the liquid fuel, the ECU 70 first opens the release valve 61 in step 5, and then operates the fuel switching valve 16 in step 6.
Here, an operation when the ECU 70 switches from a state in which the injector 30 is injecting liquid fuel to a state in which gaseous fuel is injected will be described with reference to FIGS. 6 and 7.

FIG. 6 shows a state where the injector 30 is injecting liquid fuel.
The ECU 70 communicates the second fuel pipe 22 and the third fuel pipe 23 and shuts off the first fuel pipe 21 and the third fuel pipe 23 by the operation of the fuel switching valve 16. Further, the ECU 70 closes the release valve 61. As a result, the liquid fuel supplied from the liquid fuel tank 12 to the injector 30 is injected and supplied to the intake passage 5 of the engine 2.

FIG. 7 shows an operation when the injector 30 switches from a state in which liquid fuel is injected to a state in which gaseous fuel is injected.
The ECU 70 opens the release valve 61 after the elastic portion 363 of the valve body 36 of the injector 30 is seated on the valve seat 344 or simultaneously with the seating.
When the ECU 70 opens the release valve 61, the fuel passage 31 in the injector and the liquid fuel tank 12 communicate with each other through the release passage 60. Since the pressure in the liquid fuel tank is atmospheric pressure, the fuel pressure in the fuel passage 31 of the injector 30 and the third fuel pipe 23 is rapidly reduced.

  Next, the ECU 70 operates the fuel switching valve 16, shuts off the second fuel pipe 22 and the third fuel pipe 23, and connects the first fuel pipe 21 and the third fuel pipe 23. Further, the ECU 70 opens the shut-off valve 14 and controls the drive of the regulator 15. Thereby, the gaseous fuel supplied from the first fuel pipe 21 to the third fuel pipe 23 pushes the liquid fuel in the fuel passages of the third fuel pipe 23 and the injector 30 to the release passage 60, and the third fuel pipe 23 and The fuel in the fuel passage 31 of the injector 30 is switched from liquid fuel to gaseous fuel.

In step 7 of FIG. 5, when the process for switching between the gaseous fuel and the liquid fuel is completed, or when it is time to start fuel injection during engine startup or engine operation, the ECU 70 closes the release valve 61. . That is, the ECU 70 closes the release valve 61 before the valve body 36 of the injector 30 is separated from the valve seat 344 or simultaneously with the separation.
Next, the process proceeds to step 8 where fuel injection is performed from the injector 30.

If it is time to inject fuel before the switching process between gaseous fuel and liquid fuel is completed, the ECU 70 once closes the release valve 61 in step 7 and injects fuel in step 8. In the case of the next “not in fuel injection”, the processing from step 5 to step 7 is executed again.
Whether or not the switching process between the gaseous fuel and the liquid fuel is completed can be determined by the fact that the pressure of the gaseous fuel decompressed by the regulator 15 and the fuel pressure of the release passage 60 become the same. This determination is made, for example, by comparing the output signal of the fuel temperature / fuel pressure sensor 72 provided in the first fuel pipe 21 with the output signal of the fuel temperature / fuel pressure sensor 74 provided in the release passage 60.
In addition, in order to detect the completion of the fuel switching process, the ECU 70 is previously notified of the number of times the processing of Step 5 to Step 8 is repeated or the opening time of the release valve 61 according to the rotational speed of the engine 2 and the fuel pressure. It may be memorized.

Next, the operation when the injector 30 is switched from the state injecting gaseous fuel to the state injecting liquid fuel will be described.
As shown in FIG. 5, when there is a “fuel injection switching instruction” (S1: YES) and “no fuel injection is in progress” (S3: NO), the ECU 70 executes the processing from step 5 to step 8 described above.

FIG. 8 shows a state where the injector 30 is injecting gaseous fuel.
The ECU 70 communicates the first fuel pipe 21 and the third fuel pipe 23 with the operation of the fuel switching valve 16, and shuts off the second fuel pipe 22 and the third fuel pipe 23. Further, the ECU 70 closes the release valve 61. Thereby, the gaseous fuel supplied from the high-pressure fuel tank 11 to the injector 30 is injected and supplied to the intake passage 5 of the engine 2.

FIG. 9 shows the operation when the injector 30 is switched from the state in which the gaseous fuel is injected to the state in which the liquid fuel is injected.
The ECU 70 opens the release valve 61 after the elastic portion 363 of the valve body 36 of the injector 30 is seated on the valve seat 344 or simultaneously with the seating. As a result, the fuel pressure in the fuel passage 31 of the injector 30 and the third fuel pipe 23 is rapidly reduced.

Next, the ECU 70 operates the fuel switching valve 16, shuts off the first fuel pipe 21 and the third fuel pipe 23, and connects the second fuel pipe 22 and the third fuel pipe 23. Thereby, the liquid fuel supplied from the second fuel pipe 22 to the third fuel pipe 23 pushes the gaseous fuel in the fuel passage of the third fuel pipe 23 and the injector 30 to the release passage 60, and the third fuel pipe 23 The fuel in the fuel passage 31 is switched from gaseous fuel to liquid fuel.
When the ECU 70 closes the release valve 61 in step 7, the process proceeds to step 8, and liquid fuel is injected from the injector 30 as shown in FIG.

The first embodiment has the following operational effects.
(1) In the first embodiment, when the fuel injected from the injector 30 is switched, the gaseous fuel or liquid fuel in the fuel passage 31 in the injector passes through the release passage 60 to the liquid fuel tank 12 in which the liquid fuel is stored. Released. Accordingly, it is possible to instantaneously switch between the gaseous fuel and the liquid fuel and to inject them by one injector 30. Accordingly, the space for mounting the injector 30 on the engine 2 can be reduced, and the degree of freedom in engine design can be increased. Moreover, the manufacturing cost of the fuel supply apparatus 1 can be reduced by using one injector 30.

(2) In the first embodiment, when the fuel to be injected from the injector 30 is switched, the fuel released from the release passage 60 to the liquid fuel tank 12 is purged to the intake passage 5 of the engine 2 by the fuel processing means 80, and the engine Used for driving. Therefore, consumption of liquid fuel and gaseous fuel can be reduced.

(3) In the first embodiment, the release passage 60 has one end communicating with the fuel passage 31 immediately upstream of the valve seat 344 and the other end communicating with the liquid fuel tank 12. Thereby, when the release valve 61 is opened, the fuel before switching does not stay in the vicinity of the valve seat 344 in the injector, and the fuel in the injector can be quickly discharged to the release passage 60.

(4) In the first embodiment, the ECU 70 performs the switching operation of the fuel switching valve 16 after opening the release valve 61. Thus, since the fuel switching valve 16 is switched after the fuel pressure in the fuel passage 31 is reduced, it is possible to prevent the fuel in the third fuel pipe 23 from flowing back through the fuel switching valve 16.

(5) In the first embodiment, the ECU 70 closes the release valve 61 when the fuel pressure supplied to the injector 30 by the fuel switching process and the fuel pressure in the release passage 60 become the same. Thereby, ECU70 can detect that the switch of the fuel of the fuel path 31 in an injector was completed.

(Second Embodiment)
A second embodiment of the present invention is shown in FIGS. In the second embodiment, components substantially the same as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.
The fuel supply device 10 according to the second embodiment includes a first injector 301 that injects gaseous fuel and a second injector 302 that injects liquid fuel. The fuel supply device 10 of the second embodiment includes a gaseous fuel control ECU 701 that controls a gaseous fuel system from the high-pressure fuel tank 11 to the first injector 301, and a liquid fuel system from the liquid fuel tank 12 to the second injector 302. And a liquid fuel control ECU 702 for controlling the above. Note that the gas fuel control ECU 701 and the liquid fuel control ECU 702 may be configured integrally.
Further, the fuel supply device 10 of the second embodiment does not include a fuel switching valve.

The gaseous fuel stored in the high-pressure fuel tank 11 is reduced to a predetermined pressure required by the engine 2 by the regulator 151 through the shutoff valve 14 and the cylinder fuel pipe 20, and passes through the fourth fuel pipe 24 to the first injector 301. To be supplied.
The liquid fuel stored in the liquid fuel tank 12 is pumped up by the pump 13, is increased to the required pressure of the engine 2, and is supplied to the second injector 302 through the fifth fuel pipe 25.

In the second embodiment, the regulator 151 is a variable fuel pressure regulator 151 that can adjust the pressure reduction amount of the gaseous fuel supplied from the high-pressure fuel tank 11 to the first injector 301.
The variable fuel pressure regulator 151 includes a valve for opening and closing the flow path when the gaseous fuel flowing through the flow path provided therein reaches a predetermined pressure, and an actuator capable of changing the valve closing pressure of the valve. The variable fuel pressure regulator 151 changes the pressure of the gaseous fuel supplied to the first injector 301 by changing the valve closing pressure of the valve with an actuator. The valve provided in the variable fuel pressure regulator 151 is, for example, a diaphragm valve.

The release passage 601 has one end communicating with the fuel passage of the first injector 301 and the other end communicating with the liquid fuel tank 12.
A release valve 61 provided in the release passage 601 opens or closes the release passage 601 according to a command from the gaseous fuel control ECU 701. The gaseous fuel control ECU 701 opens the release valve 61 when the fuel pressure of the gaseous fuel injected by the first injector 301 is lowered according to the operating conditions of the engine 2.
In the second embodiment, the release passage 601 is not limited to one end communicating with the fuel passage of the first injector 301, but the fourth fuel pipe 24 connecting the regulator 151 and the first injector 301, or the first Any fuel passage in one injector may be communicated with any position. This is because if the fuel passage is in the fourth fuel pipe 24 or the first injector, the pressure of the gaseous fuel supplied from the regulator 151 to the first injector 301 can be quickly reduced.

Next, the decompression switching process of the gaseous fuel of the fuel supply device 10 according to the second embodiment will be described with reference to the flowchart of FIG.
In the flowchart of FIG. 11, “step” is expressed as “S”.
This process starts when the ignition switch of the vehicle is turned on. This process may be started when gaseous fuel is injected and supplied to the engine by the gaseous fuel system.
In step 11 of FIG. 11, the gaseous fuel control ECU 701 detects whether there is a “fuel decompression switching instruction” for the gaseous fuel injected from the first injector 301. This instruction is for the gaseous fuel control ECU 701 to select the injected fuel pressure according to the operating conditions of the engine 2. If there is no “fuel pressure reduction switching instruction”, the process proceeds to step 12. In step 12, the fuel is not depressurized, and the process proceeds to step 18, where the gaseous fuel having the currently set pressure is injected from the first injector 301.

On the other hand, if there is a “fuel decompression switching instruction” in step 11, the process proceeds to step 13.
In step 13, the gaseous fuel control ECU 701 detects whether or not the first injector 301 is “injecting fuel”. “During fuel injection” means a period in which the elastic portion of the valve body of the first injector 301 is separated from the valve seat and gaseous fuel is injected from the first injector 301.
If “injecting fuel”, the process proceeds to step 14. In step 14, the fuel is not depressurized, and the process proceeds to step 18, where the gaseous fuel having the currently set pressure is injected from the first injector 301.

On the other hand, if it is determined in step 13 that “fuel is not being injected”, the process proceeds to step 15.
Here, the case where “the fuel is not being injected” refers to a period when the first injector 301 is not injecting gaseous fuel during operation of the engine 2, or before the engine is started or after the engine is stopped. This is the period during which the injection is stopped.

In the gas fuel decompression switching process, the gas fuel control ECU 701 opens the release valve 61 in step 15. As a result, the fuel passage in the first injector and the liquid fuel tank 12 communicate with each other through the release passage 601. Since the pressure in the liquid fuel tank is atmospheric pressure, the fuel passage of the first injector 301 and the gaseous fuel in the fourth fuel pipe 24 are rapidly decompressed.
Next, the gas fuel control ECU 701 lowers the set pressure of the regulator 151 to the target value in step 16. Thereby, the gaseous fuel decompressed to the target value is supplied to the first injector 301. Note that step 15 and step 16 may be performed at the same time as long as the gaseous fuel does not flow back through the regulator 151 and the operation of the regulator 151 is not hindered.

In step 17, when the gas fuel decompression switching process ends, or when it is time to start fuel injection when the engine is started or during engine operation, the gaseous fuel control ECU 701 closes the release valve 61. That is, the gaseous fuel control ECU 701 closes the release valve 61 before or simultaneously with the release of the valve body of the first injector 301 from the valve seat.
Next, the process proceeds to step 18 where fuel injection is performed from the first injector 301.

If it is time to perform fuel injection before the end of the gas fuel decompression switching process, the gaseous fuel control ECU 701 once closes the release valve 61 in step 17 and fuel injection in step 18. After performing the above, when the next “not injecting fuel”, the processing of step 15 to step 17 is executed again.
Whether or not the depressurization switching process of the gaseous fuel is completed is determined by, for example, the fuel pressure in the release passage 601 detected by the output signal of the fuel temperature / fuel pressure sensor 74 provided in the release passage 601 and the depressurization switching of the gaseous fuel. It can be detected when the target fuel pressure is the same.
In addition, the detection of the end of the decompression switching process of the gaseous fuel is performed by determining the number of times of repeating the process of step 15 to step 18 or the opening time of the release valve 61 according to the rotational speed of the engine 2 and the fuel pressure. It may be stored in advance in the gaseous fuel control ECU 701.

The second embodiment has the following effects.
(1) In the second embodiment, when the gaseous fuel injected by the first injector 301 is depressurized, the gaseous fuel in the first injector is discharged via the release passage 601 to the liquid fuel tank 12 in which the liquid fuel is stored. To do. Thereby, it is possible to depressurize gaseous fuel instantaneously.

(2) In the second embodiment, the gaseous fuel released from the first injector 301 to the liquid fuel tank 12 is purged into the intake passage 5 of the engine 2 by the fuel processing means 80 and can be used for driving the engine. is there. Therefore, consumption of gaseous fuel can be reduced.

(3) In the second embodiment, the gaseous fuel control ECU 701 has the same pressure reduction target pressure detected by the output of the fuel temperature / fuel pressure sensor 74 provided in the release passage 601 and the fuel pressure in the release passage 601. At this time, the release valve 61 is closed. Thereby, gaseous fuel control ECU701 can detect that the decompression switching process of gaseous fuel was complete | finished.

(4) In the second embodiment, the fuel supply device 10 includes a variable fuel pressure regulator 151. Thereby, the fuel pressure injected from the 1st injector 301 can be adjusted appropriately to the pressure which the engine 2 requires, and the consumption of gaseous fuel can be reduced.

(Other embodiments)
(1) In the above-described embodiment, the fuel supply device that supplies fuel to the bi-fuel engine has been described. On the other hand, in other embodiments, the fuel supply device may supply fuel to the multi-fuel engine.
(2) In the above-described embodiment, the fuel supply device including the injector that injects and supplies fuel to the intake passage of the engine has been described. On the other hand, in other embodiments, the injector may inject fuel directly into the cylinder of the engine.

(3) In the above-described embodiment, the second fuel is a liquid fuel, and the first fuel is a gaseous fuel. On the other hand, in another embodiment, on the condition that the pressure at which the low-pressure fuel tank stores the second fuel is smaller than the injection pressure of the first fuel and the injection pressure of the second fuel injected from the injector, Both the first fuel and the second fuel may be gaseous fuel. In this case, both the low pressure fuel tank and the high pressure fuel tank are pressure vessels.
(4) In the above-described embodiment, the fuel temperature / fuel pressure sensor is provided. On the other hand, in other embodiments, only the fuel temperature sensor or only the fuel pressure sensor may be provided as necessary.

(5) In another embodiment, the first embodiment and the second embodiment described above are combined, and in the configuration of the first embodiment described above, the gaseous fuel or liquid injected from the injector according to the demand of the engine It is also possible to depressurize the fuel.
As described above, the present invention is not limited to the above-described embodiment, and can be implemented in various forms within the scope of the invention in addition to combining the plurality of embodiments.

DESCRIPTION OF SYMBOLS 1,10 ... Fuel supply apparatus 11 ... High pressure fuel tank 12 ... Liquid fuel tank (low pressure fuel tank)
31 ... Fuel passage 344 ... Valve seat 36 ... Valve body 354 ... Injection hole 30, 301, 302 ... Injector 60, 601 ... Release passage 61 ... Release valve 70, 701 702 ... Electronic control device (control means)

Claims (13)

A high-pressure fuel tank (11) for storing the first fuel;
A valve body (36) seated and separated from a valve seat (344) provided on an inner wall of a fuel passage (31) to which the first fuel is supplied from the high-pressure fuel tank; An injector (30, 301, 302) for injecting the first fuel from a provided nozzle hole (354);
A low pressure fuel tank (12) for storing the second fuel at a pressure lower than an injection pressure when the injector injects the first fuel;
Release passages (60, 601) communicating the fuel passage upstream of the valve seat of the injector and the low-pressure fuel tank;
A release valve (61) for opening or closing the release passage;
The release valve is opened when the first fuel in the fuel passage of the injector is discharged to the low-pressure fuel tank, and the release valve is closed when the injector injects the first fuel from the injection hole. And a control means (70, 701, 702) that controls the fuel supply device (1, 10).   2. The fuel supply device according to claim 1, wherein a pressure at which the low-pressure fuel tank stores the second fuel is lower than a pressure at which the high-pressure fuel tank stores the first fuel.   The fuel supply apparatus according to claim 1, wherein the first fuel and the second fuel are different types of fuel.   The fuel supply apparatus according to any one of claims 1 to 3, wherein the first fuel is a gaseous fuel and the second fuel is a liquid fuel. The fuel passage of the injector and the high-pressure fuel tank are communicated or blocked, and the fuel passage of the injector and the low-pressure fuel tank are communicated or blocked, and the first fuel supplied to the injector and the first fuel are supplied to the injector. A fuel switching valve (16) for switching between two fuels;
The injector injects the first fuel and the second fuel,
The low-pressure fuel tank stores the second fuel at a pressure lower than an injection pressure when the injector injects the first fuel and lower than an injection pressure when the injector injects the second fuel. Is what
The control means opens a release valve when discharging the first fuel or the second fuel flowing through the fuel passage of the injector to a low-pressure fuel tank, and the injector is configured to open the first fuel or the fuel from the nozzle hole. The fuel supply device (1) according to any one of claims 1 to 4, wherein the release valve is closed when the second fuel is injected.   6. The fuel supply apparatus according to claim 5, wherein one end of the release passage communicates with the fuel passage immediately upstream of the valve seat, and the other end communicates with the low-pressure fuel tank. The control means includes
After the valve body of the injector is seated on the valve seat or simultaneously with the seating, the release valve is opened,
After the release valve is opened, the fuel switching valve is switched,
The fuel supply device according to claim 5 or 6, wherein the release valve is closed before or simultaneously with the valve body of the injector separating from the valve seat.   When the fuel pressure of the first fuel or the second fuel supplied to the injector by the switching operation of the fuel switching valve becomes the same as the fuel pressure of the release passage, the control means Is closed, The fuel supply device according to any one of claims 5 to 7.   5. The fuel supply device according to claim 1, wherein the control unit performs pressure reduction of the first fuel flowing through the fuel passage of the injector by opening the release valve. 6. (10).   The said control means closes the said release valve, when the pressure reduction target pressure of the said 1st fuel supplied to the said injector and the fuel pressure of the said release channel become the same. The fuel supply device described in 1.   The fuel supply device according to claim 9 or 10, further comprising a variable fuel pressure regulator (151) capable of adjusting a pressure reduction amount of the first fuel supplied from the high-pressure fuel tank to the injector.   Fuel processing means (80) for supplying the gaseous fuel discharged from the release passage to the low-pressure fuel tank and the evaporated fuel evaporated from the liquid fuel to an intake passage of an engine to which the injector supplies fuel from the low-pressure fuel tank. The fuel supply device according to any one of claims 4 to 11, further comprising: The fuel processing means includes
A canister (82) having an adsorbent that adsorbs the gaseous fuel discharged from the release passage to the low-pressure fuel tank and the evaporated fuel evaporated from the liquid fuel;
A purge passage (81) connecting the intake passage and the canister of the engine for supplying fuel by the injector;
The purge valve (83) provided in the purge passage and discharging the gaseous fuel and the evaporated fuel adsorbed by the adsorbent of the canister to the intake passage. Fuel supply system.

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