JP2014013041A - Fuel supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel supply system enabling improvement of vaporization accuracy of vaporized fuel supplied from a vaporization chamber to an intake passage and improvement of work efficiency for generating the vaporized fuel.SOLUTION: In a fuel supply system 2-5 for supplying vaporized fuel to an intake passage 29 of an internal combustion engine 10, liquid fuel injected from a sub injector 38 is vaporized in a vaporization chamber 41 and is supplied to the intake passage 29. At this time, remaining liquid fuel that is not vaporized in the vaporization chamber 41 is discharged to a fuel tank chamber 31 through a return passage 66. Liquid level detection means 80 determines a gas-liquid state where fluid in the return passage 66 is gas or liquid at a predetermined first height and at a second height on a side of a lower position than that of the first height. A relief valve 69 communicates or blocks the return passage 66 in accordance with a command from an ECU 100. On the basis of detection information from the liquid level detection means 80, the liquid fuel remaining in the vaporization chamber 41 can be efficiently discharged.

Description

  The present invention relates to a fuel supply device that supplies vaporized fuel to an internal combustion engine.

  Conventionally, in an internal combustion engine in which the start of combustion is controlled by spark ignition, generally, liquid fuel injected and supplied from an injector into a combustion chamber is vaporized and spark ignition is performed. However, particularly when the internal combustion engine is started in the cold state, the injected fuel tends to adhere to the inner wall surface of the low-temperature cylinder, and the fuel vaporization is delayed. As a result, unburned HC (hydrocarbon) tends to increase, and wet components remaining on the wall surface when the internal combustion engine is stopped generate particulate matter and deposits (deposits). This causes a problem that these unburned HC, particulate matter, and the like are discharged from the exhaust port into the atmosphere as emissions (exhaust materials).

  On the other hand, the fuel supply device described in Patent Document 1 is provided with a system for injecting and supplying gaseous fuel evaporated in the fuel tank from the sub-injector separately from the system for supplying and injecting liquid fuel from the main injector. In addition, liquid fuel and gaseous fuel are injected and supplied together when the internal combustion engine is started, thereby suppressing the generation of wet components in the cylinder and reducing emissions.

JP 2003-343365 A

In the prior art described in Patent Document 1, when a part of the gaseous fuel evaporated in the fuel tank is condensed in the middle of the piping until reaching the sub-injector and becomes liquid fuel, the liquid fuel is separated and discharged. There is no means to do. Therefore, the liquid component is mixed with the gaseous fuel to be supplied by injection, and the “vaporization accuracy” of the vaporized fuel is lowered.
In addition, when means for discharging the liquid fuel condensed in the middle of the piping is provided, if the gaseous fuel and the liquid fuel cannot be properly separated, a part of the gaseous fuel is discharged at the same time when the liquid fuel is discharged. Is done. Then, a part of gaseous fuel will be consumed without being used effectively.

In addition, the present applicant has previously filed Japanese Patent Application No. 2010-030325. In the invention according to this application, the “vaporized fuel chamber (vaporized chamber)” that stores the vaporized liquid fuel injected from the “second injection valve (sub-injector)”, and the vaporized fuel chamber and the intake passage A “purge valve” that switches between communication and cutoff is provided, and supply of vaporized fuel from the vaporized fuel chamber to the combustion chamber is controlled by opening and closing the purge valve.
In the invention according to this application, the liquid fuel remaining without being vaporized in the vaporized fuel chamber has the same problem as the problem in the prior art. That is, if the liquid fuel cannot be appropriately separated and discharged from the gaseous fuel, there arises a problem that the vaporization accuracy of the vaporized fuel supplied to the intake passage is lowered. Further, if a part of the vaporized fuel is discharged at the same time when the liquid fuel is discharged from the vaporized fuel chamber, a part of the generated gaseous fuel is consumed without being used effectively. In this case, in order to generate vaporized fuel, for example, a fuel pump pumps up liquid fuel and supplies it to the sub-injector. The ratio of “amount of vaporized fuel supplied to the combustion chamber and used effectively” with respect to the total amount of vaporized fuel generated by the work of this fuel pump or the like is called “work efficiency”. When a part of the vaporized fuel is consumed without being used effectively, work efficiency is lowered.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to appropriately separate liquid fuel remaining in the vaporization chamber from the vaporized fuel and discharge the liquid fuel from the vaporization chamber to the intake passage. An object of the present invention is to provide a fuel supply device that improves the vaporization accuracy of vaporized fuel to be supplied and improves work efficiency for generating vaporized fuel.

The fuel supply device according to any one of claims 1 to 3, wherein the fuel supply device supplies vaporized fuel to an intake passage of an internal combustion engine, and includes a vaporized fuel tank, a vaporized chamber injection valve, a fuel pump, a return passage member, and a liquid discharge valve. And valve opening / closing control means.
The vaporized fuel tank internally forms a vaporization chamber for vaporizing the liquid fuel.
The vaporization chamber injection valve injects liquid fuel into the vaporization chamber.
The fuel pump pumps liquid fuel from a fuel tank chamber in a fuel tank provided on the lower side in the gravity direction of the vaporized fuel tank, and supplies the liquid fuel to the vaporization chamber injection valve.
The return passage member forms a return passage for returning the liquid fuel remaining in the vaporization chamber to the fuel tank chamber by gravity.
The liquid discharge valve communicates or blocks the return passage.
The valve opening / closing control means controls opening / closing of the liquid discharge valve.

The fuel supply device according to claim 1 further includes a liquid level detecting means.
The liquid level detecting means detects whether or not the liquid level in the return passage is within a predetermined range.
And a liquid discharge valve opens and closes based on the information of the liquid level height by a liquid level detection means.

  Specifically, the fuel supply device can appropriately separate the liquid fuel remaining in the vaporization chamber from the vaporized fuel and open the fuel discharge tank by opening the liquid discharge valve. Therefore, the liquid component contained in the vaporized fuel in the vaporization chamber can be reduced, and the vaporization accuracy of the vaporized fuel supplied from the vaporization chamber to the intake passage can be improved.

  More specifically, the fuel supply device opens the liquid discharge valve, discharges the liquid fuel from the vaporization chamber, and then closes the liquid discharge valve as soon as the liquid fuel is completely discharged. Minimize emissions. Thereby, since waste of vaporized fuel is suppressed, work efficiency of a fuel pump or the like for generating vaporized fuel can be improved.

Further, the liquid level detection means is configured to determine whether the fluid in the return passage is a gas or a liquid at a predetermined first height and a second height lower than the first height. judge.
The valve opening / closing control means opens the liquid discharge valve when the liquid level detection means determines that the fluid in the return passage is liquid at the first height, and the fluid in the return passage at the second height. When the liquid level detecting means determines that is a gas, the liquid discharge valve is closed.
Thereby, the liquid fuel remaining in the vaporization chamber can be efficiently discharged based on detection information by various liquid level detection means using the physical property difference between the liquid and the gas.

A fuel supply apparatus according to a second aspect of the present invention includes an internal pressure detection means for detecting the internal pressure of the vaporization chamber in place of the liquid level detection means in the fuel supply apparatus according to the first aspect.
The valve opening / closing control means opens the liquid discharge valve when the internal pressure detection value detected by the internal pressure detection means exceeds a predetermined upper limit threshold, and the internal pressure detection value detected by the internal pressure detection means is less than the predetermined lower limit threshold. When it becomes, the liquid discharge valve is closed.
Thereby, the liquid fuel remaining in the vaporization chamber can be efficiently discharged based on the detection information of the internal pressure detection means.

The fuel supply device according to claim 3 does not include any of the liquid level detection means in the fuel supply device according to claim 1 and the internal pressure detection means in the fuel supply device according to claim 2.
The valve opening / closing control means opens the liquid discharge valve for a predetermined period after the vaporization chamber injection valve injects fuel into the vaporization chamber, and closes the liquid discharge valve after the predetermined period.
Thereby, the liquid fuel remaining in the vaporization chamber can be easily discharged without providing any liquid level detection means and internal pressure detection means.

According to the fourth aspect of the present invention, the vaporized fuel tank is heated by the vaporized fuel tank heating means. Thereby, the production | generation of the vaporization fuel in a vaporization chamber can be accelerated | stimulated.
According to the fifth aspect of the present invention, the fuel supplied to the vaporization chamber injection valve is heated by the fuel heating means. Thereby, the temperature of the liquid fuel injected can be raised and the production | generation of the vaporization fuel in a vaporization chamber can be accelerated | stimulated.

It is a schematic block diagram of the fuel supply apparatus by 1st Embodiment of this invention. (B) is the principal part enlarged view of FIG. 1, (a) is an aa sectional drawing of (b). It is a schematic block diagram of the fuel supply apparatus by 2nd-5th embodiment of this invention. It is a principal part enlarged view of the fuel supply apparatus by 2nd Embodiment of this invention. It is a principal part enlarged view of the fuel supply apparatus by 3rd Embodiment of this invention. It is a principal part enlarged view of the fuel supply apparatus by 4th Embodiment of this invention. It is a principal part enlarged view of the fuel supply apparatus by 5th Embodiment of this invention. It is a schematic block diagram of the fuel supply apparatus by 6th Embodiment of this invention. It is a schematic diagram which shows the vaporization chamber internal pressure change of the fuel supply apparatus by 6th Embodiment of this invention. It is a schematic block diagram of the fuel supply apparatus by 7th Embodiment of this invention.

Hereinafter, a fuel supply device according to an embodiment of the present invention will be described with reference to the drawings. In the following description of the embodiments, substantially the same parts are denoted by the same reference numerals and description thereof is omitted.
Note that the first embodiment corresponds to a reference embodiment.
(First embodiment)
FIG. 1 shows an internal combustion engine system 99 to which the fuel supply apparatus according to the first embodiment of the present invention is applied. The internal combustion engine system 99 is a system that supplies fuel such as gasoline and air to the four-cylinder internal combustion engine 10. FIG. 1 shows a cross section of one of the four cylinders.

The internal combustion engine 10 includes a cylinder block 11, a cylinder head 12, a piston 13, a spark plug 14, and the like. The cylinder block 11 has a cylinder 18 formed in a cylindrical shape, and accommodates the piston 13 so as to be capable of reciprocating inside the cylinder 18. The piston 13 is connected to the crankshaft 17 via a connecting rod 16.
The spark plug 14 sparks the fuel mixture introduced into the combustion chamber 19 when a high voltage for spark discharge is applied according to a command from the ECU (electronic control unit) 100.
A heat exchange member 50 having a heat exchange chamber 51 is provided outside the cylinder block 11. The heat exchange liquid Hw circulates in the heat exchange chamber 51, and the high heat of the cylinder block 11 and the low heat of the heat exchange liquid Hw are heat-exchanged. The heat exchange liquid Hw is, for example, engine cooling water.

  The cylinder head 12 is provided with an intake valve 21 that opens and closes between the intake port 22 and the combustion chamber 19, and an exhaust valve 26 that opens and closes between the exhaust port 27 and the combustion chamber 19. The combustion chamber 19 is a space surrounded by the inner wall surface of the cylinder 18, the cylinder head 12, the intake valve 21, the exhaust valve 26 and the top surface of the piston 13. The combustion chamber 19 communicates with the intake port 22 when the intake valve 21 opens, and communicates with the exhaust port 27 when the exhaust valve 26 opens. The intake port 22 communicates with an intake passage 29, and the exhaust port 27 communicates with an exhaust passage (not shown).

  The intake passage 29 is formed by the intake pipe 28. An air cleaner 23 and a throttle valve 24 are disposed in the intake pipe 28. The air cleaner 23 removes foreign substances in the air sucked into the intake passage 29. The throttle valve 24 adjusts the amount of air sucked.

The fuel tank 30 is provided below the cylinder block 11 in the direction of gravity. Liquid fuel such as gasoline is stored in the fuel tank chamber 31 inside the fuel tank 30.
The fuel pump 33 pumps up the liquid fuel in the fuel tank chamber 31 via the fuel passage 32 formed by the fuel passage member 320. On the discharge side of the fuel pump 33, the fuel passage branches into a fuel passage 34 formed by the fuel passage member 340 and a branch passage 35 formed by the branch passage member 350.

The fuel passage 34 communicates with the suction side of the high-pressure fuel pump 36. The high pressure fuel pump 36 pressurizes the liquid fuel supplied from the fuel pump 33 and supplies it to the main injector 37. The main injector 37 injects and supplies high pressure fuel to the combustion chamber 19.
The branch passage 35 communicates with a sub-injector 38 constituting the fuel supply device 1.

Next, the fuel supply device 1 will be described. The fuel supply device 1 supplies the vaporized fuel generated in the vaporization chamber 41 to the intake passage 29 via the vaporized fuel passage 93 and the purge valve 95, and the liquid fuel remaining without being vaporized in the vaporization chamber 41. Then, the fuel is discharged into the fuel tank chamber 31 via the return passages 62 and 64.
The fuel supply device 1 includes a vaporized fuel tank 40 forming a vaporization chamber 41, a sub-injector 38 as a “vaporization chamber injection valve”, a fuel pump 33, return passage members 61 and 63, a float valve device 70, and the like.

The vaporized fuel tank 40 is a pressure vessel that forms a vaporization chamber 41 therein. The vaporized fuel tank 40 is provided with a contact wall 43, which is one side wall, in contact with the heat exchange member 50 outside the cylinder block 11. The vaporized fuel tank 40 is heated by the heat exchange member 50 heated through the cylinder block 11 by the combustion of fuel in the combustion chamber 19. The heat exchange member 50 corresponds to a “vaporized fuel tank heating unit” recited in the claims.
A temperature sensor 53 is provided on the inner wall 52 of the heat exchange chamber 51 adjacent to the vaporized fuel tank 40. The temperature detection value detected by the temperature sensor 53 is output to the ECU 100.

  A sub-injector 38 is provided on the side wall 44 facing the contact wall 43 of the vaporized fuel tank 40. The sub-injector 38 injects the liquid fuel supplied from the fuel pump 33 via the branch passage 35 toward the contact wall 43. The liquid fuel injected from the sub-injector 38 is vaporized in the vaporization chamber 41 heated by the heat of the heat exchange member 50.

A heating chamber 57 is formed on the radially outer side of the branch passage member 350. The heating chamber 57 communicates with the heat exchange chamber 51 via a heating passage 56 formed by the heating passage member 55. The heat exchange liquid Hw in the heat exchange chamber 51 warmed by the cylinder block 11 flows into the heating chamber 57 via the heating passage 56, so that the liquid fuel supplied to the sub-injector 38 through the branch passage 35. Heated. The heat exchange liquid Hw corresponds to “fuel heating means” described in the claims.
Further, a check valve 39 is provided in the branch passage 35 on the fuel pump 33 side from the heating chamber 57. The check valve 39 prevents the heated liquid fuel from flowing back to the fuel pump 33 side.

  The fuel vaporized in the vaporization chamber 41 is introduced into the vaporized fuel passage 93 from the vaporized fuel passage side communication portion 46 provided in the upper portion of the vaporization chamber 41. The vaporized fuel passage 93 is formed by the vaporized fuel passage member 930 and communicates the vaporization chamber 41 and the intake passage 29. A purge valve 95 provided in the vaporized fuel passage 93 switches communication and cutoff between the vaporization chamber 41 and the intake passage 29. When the purge valve 95 is opened, the vaporized fuel is supplied to the combustion chamber 19 together with the intake air via the intake passage 29 and the intake port 22.

For example, the purge valve 95 is closed by a command from the ECU 100 after a period corresponding to a predetermined number of combustions has elapsed. That is, after a predetermined number of combustions are completed, fuel is supplied to the combustion chamber 19 by injection from the main injector 37. The number of combustions until the purge valve 95 is closed is determined based on the capacity of the vaporized fuel tank 40.
Here, the ECU 100 controls fuel injection of the main injector 37 and the sub-injector 38, opening / closing of the purge valve 95, and the like based on input information such as the accelerator opening and the engine speed. In FIG. 1, a part of the control line input / output to / from ECU 100 is omitted in order to avoid complication.

  A protective wall 48 that prevents liquid fuel injected from the sub-injector 38 from directly flowing into the vaporized fuel passage 93 is provided in the vicinity of the vaporized fuel passage side communication portion 46. The protective wall 48 is provided so as to be inclined from the upper part of the contact wall 43 toward the injection hole of the sub-injector 38 so as to substantially follow the injection shape from the sub-injector 38. The vaporized fuel flows into the vaporized fuel passage side communication portion 46 through a gap 49 formed between the side wall 44 and the protective wall 48.

  A return passage side communication portion 47 that communicates with the upper return passage 62 is provided below the vaporized fuel tank 41. The liquid fuel remaining without being vaporized in the vaporization chamber 41 is collected by gravity under the vaporization chamber 41 and is discharged from the return passage side communication portion 47 to the float valve device 70 via the upper return passage 62. The float valve device 70 communicates with the fuel tank chamber 31 in the fuel tank 30 via the lower return passage 64. The upper return passage 62 is formed by the upper return passage member 61, and the lower return passage 64 is formed by the lower return passage member 63.

  Next, the float valve device 70 will be described in detail with reference to FIG. The float valve device 70 includes a housing 71, a float 72, a fuel pressure cylinder 73, and the like.

  The housing 71 forms a float chamber 71a inside. An inlet 71b communicating with the upper return passage 62 is provided at the upper part of the float chamber 71a. A discharge port 71c protruding from the bottom 71e is provided at the lower part of the float chamber 71a. The float chamber 71a communicates with the lower return passage 64 via the discharge port 71c. The upper end surface of the discharge port 71c forms an annular valve seat 71d on which a hollow spherical float 72 can be seated.

  The liquid fuel Lq that has flowed into the float chamber 71a from the vaporization chamber 41 accumulates at the bottom 71e of the float chamber 71a. Here, when the inflow port 71b is opened to the atmosphere and the discharge port 71c is closed, if the liquid level is lower than a predetermined height, the float 72 cannot obtain buoyancy and cannot float. On the other hand, when the liquid level is higher than a predetermined height, the float 72 floats by obtaining the buoyancy Fu. If the predetermined liquid level height at this time is “switching height L0”, whether the liquid level is lower or higher than the switching height L0 can be detected by the behavior of the float 72.

  Further, as a general rule, when the liquid level is lower than the switching height L0, the float 72 is seated on the valve seat 71d, closes the discharge port 71c, and blocks the discharge of the liquid fuel Lq. When the liquid level is higher than the switching height L0, the buoyancy Fu separates the valve seat 71d, opens the discharge port 71c, and allows the liquid fuel Lq to be discharged.

However, when the inflow port 71b communicates with the vaporization chamber 71b, the discharge port 71c communicates with the fuel tank 71c, and the float chamber 71a becomes a “closed space”, an adsorption force Fd due to a differential pressure is formed above and below the float 72. Occurs and the float 72 is adsorbed to the valve seat 71d.
That is, the internal pressure of the upper return passage 62 and the space above the float 72 is equal to the vaporization chamber internal pressure Pch, and the internal pressure of the lower return passage 64 below the float 72 is equal to the fuel tank indoor pressure Pta. The vaporization chamber internal pressure Pch is larger than the fuel tank indoor pressure Pta. Therefore, if the inner diameter of the lower return passage 64 is D, the suction force Fd calculated by the equation (1) acts downward on the top and bottom of the float 72.
^{Fd = πD 2/4 × (} Pch-Pta) ··· Equation (1)

In this case, in order for the float 72 to float against the adsorption force Fd, the volume of the float 72 must be increased so that a large buoyancy Fu can be obtained. However, in reality, it is difficult to increase the volume of the float 72 due to space limitations of the float chamber 71a.
Therefore, the float valve device 70 includes an edge 74. The edge 74 is formed integrally with the fuel pressure cylinder 73 and enters a wedge shape between the float 72 and the valve seat 71d as the fuel pressure cylinder 73 reciprocates.

  The fuel pressure cylinder 73 is accommodated in a cylinder chamber 71f provided in the housing 71 in a substantially horizontal direction so as to be reciprocally movable. A fuel pressure introduction hole 71g for introducing the fuel injection pressure of the sub-injector 38 is formed at one end of the cylinder chamber 71f. The fuel pressure cylinder 73 is driven forward by the fuel injection pressure. In addition, a pressure release hole 71h for releasing the pressure generated by the movement of the fuel pressure cylinder 73 is formed at the other end of the cylinder chamber 71f, and a spring for biasing the fuel pressure cylinder 73 to the return side. 75 is provided. When the fuel injection pressure is not introduced into the fuel pressure introduction hole 71g, the fuel pressure cylinder 73 moves to the return side.

(Function)
Next, the operation of the fuel supply device 1 of the first embodiment will be described.
In the internal combustion engine system 99, fuel is supplied to the combustion chamber 19 by two systems. In one system, high-pressure fuel pumped from the fuel tank chamber 31 by the fuel pump 33 and pressurized by the high-pressure fuel pump 36 is injected from the main injector 37 into the combustion chamber 19. In the other system, the vaporized fuel generated by the fuel supply device 1 is introduced into the intake passage 29 via the vaporized fuel passage 93 and supplied to the combustion chamber 19 together with the intake air. The fuel supply device 1 injects the liquid fuel pumped up from the fuel tank chamber 31 by the fuel pump 33 from the sub-injector 38 to the vaporization chamber 41, vaporizes and stores the fuel in the vaporization chamber 41.

  The internal combustion engine system 99 opens the purge valve 95 of the vaporized fuel passage 93 when the internal combustion engine is started, and supplies the vaporized fuel to the combustion chamber 19. Thereby, the wet component in the cylinder 18 is suppressed and emission is reduced. Moreover, since the internal pressure of the vaporization chamber 41 is higher than the atmospheric pressure due to the vapor pressure of the vaporized fuel, oxygen in the intake air is prevented from being mixed into the vaporized fuel. Therefore, the generation of deposits due to the oxidation of HC in the vaporized fuel is suppressed.

  Further, of the liquid fuel injected from the sub-injector 38, the liquid fuel remaining without being vaporized in the vaporization chamber 41 flows into the float chamber 71a of the float valve device 70 via the upper return passage 62. When the sub-injector 38 does not inject fuel, the float 72 accommodated in the float chamber 71a is seated on the valve seat 71d by the adsorption force Fd generated by the differential pressure between the vaporization chamber internal pressure Pch and the fuel tank internal pressure Pta.

  When the fuel injection of the sub-injector 38 is started, the fuel injection pressure is introduced from the fuel pressure introduction hole 71g into the cylinder chamber 71f, and the fuel pressure cylinder 73 moves forward. Accordingly, an edge 74 formed integrally with the fuel pressure cylinder 73 enters a wedge shape between the float 72 and the valve seat 71d. Thereby, the edge 74 separates the floating 72 from the valve seat 71d and closes the discharge port 71c. For this reason, the suction force Fd does not act on the float 72. Further, the liquid fuel flowed in from the vaporizing chamber 41 raises the liquid level in the float chamber 71a above the switching height L0, and the float 72 floats with the buoyancy Fu.

  When the fuel injection of the sub-injector 38 is finished, the fuel pressure cylinder 73 is moved to the return side by the urging force of the spring 75, and the edge 74 opens the discharge port 71c accordingly. Then, the liquid fuel in the float chamber 71a is discharged from the discharge port 71c to the fuel tank chamber 31 via the lower return passage 64, and the liquid level in the float chamber 71a is lowered below the switching height L0. Further, since the suction force Fd acts on the float 72, the float 72 is seated on the valve seat 71d. Therefore, the vaporized fuel in the vaporization chamber 41 is not discharged simultaneously with the liquid fuel.

(effect)
With the above configuration, the fuel supply device 1 according to the first embodiment has the following effects.
(1) In the float valve device 70 as the liquid level detection means and the liquid discharge valve, the float 72 as the valve body has a liquid level height in the float chamber 71a from the switching height L0 due to the liquid fuel flowing from the vaporization chamber 41. When it gets higher, it opens. Thereby, the liquid fuel remaining in the vaporization chamber 41 can be appropriately separated and discharged from the discharge port 71 c of the float valve device 70 to the fuel tank chamber 31 via the lower return passage 64. Therefore, the liquid component contained in the vaporized fuel in the vaporization chamber 41 can be reduced, and the vaporization accuracy of the vaporized fuel supplied from the vaporization chamber to the intake passage 29 can be improved.

  (2) The float 72 is closed when the liquid fuel from the vaporization chamber 41 is discharged from the discharge port 71c and the liquid level in the float chamber 71a becomes lower than the switching height L0, thereby discharging the vaporized fuel. Minimize. Thereby, since waste of vaporized fuel is suppressed, work efficiency for generating vaporized fuel can be improved. Here, the work for generating the vaporized fuel includes, in addition to the work of the fuel pump 33, the work of the heat exchange member 50 as the vaporization chamber heating means and the heat exchange liquid Hw as the fuel heating means.

  (3) By using the float 72 as the liquid level detection means, the configuration of the fuel supply device 1 that is simple and has a low possibility of failure is realized. Further, since the float 72 also serves as the valve body of the liquid discharge valve, an independent liquid discharge valve is not necessary, and the number of parts and the manufacturing cost of the fuel supply device 1 can be reduced.

  (4) The float valve device 70 includes an edge 74 as a detaching means for forcibly separating the float 72 seated on the valve seat 71d from the valve seat 71d under the action of the adsorption force Fd. Thereby, the float valve device 70 can be opened and closed without increasing the volume of the float 72.

  (5) The fuel pressure cylinder 73 provided with the edge 74 as detachment means is driven by the fuel injection pressure of the sub-injector 38. Since the liquid level of the float chamber 71a rises when the sub-injector 38 injects liquid fuel into the vaporization chamber 41, the float 72 is driven by driving the edge 74 using the fuel injection pressure of the sub-injector 38. The timing at which the fuel is separated is synchronized with the fuel injection timing of the sub-injector 38, so that the liquid fuel can be discharged efficiently. Further, it is not necessary to provide another driving means.

  (6) Since the vaporized fuel tank 40 is provided in contact with the heat exchange member 50, the vaporization chamber 41 is heated by the heat of the heat exchange chamber 51, so that the generation of vaporized fuel in the vaporization chamber 41 can be promoted. it can. The sub-injector 38 injects liquid fuel toward the contact wall 43 which is provided on the side wall 44 facing the contact wall 43 and is heated. Therefore, the liquid fuel injected from the sub injector 38 can be efficiently vaporized.

  (7) The heat exchange liquid Hw heated by the heat of the cylinder block 11 flows into the heating chamber 57 formed on the radially outer side of the branch passage member 350, and is supplied to the sub injector 38 through the branch passage 35. The liquid fuel is heated. Thereby, the temperature of the liquid fuel injected can be raised and the production | generation of the vaporization fuel in the vaporization chamber 41 can be accelerated | stimulated.

(Second to fifth embodiments)
Then, 2nd-5th embodiment of this invention is described based on FIGS.
As shown in FIG. 3, the fuel supply devices 2 to 5 of the second to fifth embodiments include independent liquid level detection means 80 instead of the float valve device 70 in the fuel supply device 1 of the first embodiment, and A relief valve 69 as a “liquid discharge valve” is provided, and an ECU 100 as a “valve opening / closing control means” is further provided.

The liquid level detection means 80 is provided inside the return passage 66 or is provided across the inside and outside of the return passage 66. The liquid level detection means 80 determines whether the fluid in the return passage 66 is a gas or a liquid at a predetermined first height L1 and a second height L2 that is lower than the first height L1. Determine the gas-liquid state. Thereby, the liquid level detection means 80 detects whether the height of the liquid level is within a predetermined range.
In the second to fifth embodiments, the form of the liquid level detecting means 80 is different.

  The relief valve 69 is provided in the middle of the return passage 66 and communicates or blocks the return passage 66 in accordance with a command from the ECU 100. By opening the relief valve 69, the fuel in the vaporization chamber 41 is discharged to the fuel tank chamber 31 by gravity via the return passage 66. Further, the fuel discharge is stopped by closing the relief valve 69.

(Second Embodiment)
As shown in FIG. 4, the liquid level detection means 802 of the second embodiment includes two sets of heaters 771 and 772, thermocouples 781 and 782, and thermoelectrometers 791 and 792 having the same specifications.
The thermocouples 781 and 782 are, for example, K thermocouples. The height of the temperature measuring junction of the first thermocouple 781 is set to the first height L1, and the height of the temperature measuring contact of the second thermocouple 782 is set to the second height L2 which is lower than the first height L1. Is set. The heaters 771 and 772 are, for example, rod-shaped cartridge heaters or sheath heaters. The first heater 771 is provided near the temperature measuring contact of the first thermocouple 781, and the second heater 772 is provided near the temperature measuring contact of the second thermocouple 782. The distance between the first heater 771 and the temperature measuring contact of the first thermocouple 781 is substantially equal to the distance between the second heater 772 and the temperature measuring contact of the second thermocouple 782. First thermoelectromotive force meter 791 and second thermoelectromotive force meter 792 detect the temperature of the temperature measuring junction from the thermoelectromotive forces of first thermocouple 781 and second thermocouple 782, respectively.

  The first heater 771 and the second heater 772 are supplied with the same electric power and generate heat. Here, the thermal conductivity of the liquid is about 10 times larger than the thermal conductivity of the gas. Therefore, when the temperature measuring contacts of the thermocouples 781 and 782 are in the liquid Lq, the amount of heat Q conducted with the heat generated by the heater is large, and the detected temperature of the thermocouple rapidly increases. On the other hand, when the temperature measuring contacts of the thermocouples 781 and 782 are in the gas Vp, the amount of heat Q conducted with the heat generated by the heater is small, and the detected temperature of the thermocouple rises slowly. Therefore, the gas-liquid state of the first height L1 and the second height L2 can be determined based on the detection values of the thermoelectromotive force meters 791 and 792.

  The ECU 100 opens the relief valve 69 when the liquid level detecting means 802 detects the liquid Lq at the first height L1. Then, the liquid fuel is discharged and the liquid level Lf is lowered. Further, the ECU 100 closes the relief valve 69 when the liquid level detecting means 802 detects the gas Vp at the second height L2. Then, the discharge of liquid fuel is stopped. Thereafter, the liquid fuel in the vaporization chamber 41 flows into the return passage 66, and the liquid level Lf gradually rises. When the liquid level Lf reaches the first height L1 again, the ECU 100 opens the relief valve 69. In this way, the liquid level Lf is controlled so as to be maintained between the first height L1 and the second height L2.

(Third embodiment)
As shown in FIG. 5, the liquid level detection means 803 of the third embodiment includes two sets of light sources 811 and 812 and light quantity sensors 821 and 822 having the same specifications. The return passage member 67 is formed of a light transmission member.
The light sources 811 and 812 are, for example, LEDs. The first light source 811 and the first light quantity sensor 821 are provided on the opposite sides of the return passage 66 and at the first height L1. The second light source 812 and the second light amount sensor 822 are provided on the opposite sides of the return passage 66 and at a second height L2 that is lower than the first height L1.
The light emitted by the first light source 811 and the second light source 812 enters perpendicularly to the axis of the return path 66, and part of the light is transmitted to the opposite side. The first light amount sensor 821 and the second light amount sensor 822 detect the amount of transmitted light.

  The first light source 811 and the second light source 812 emit equivalent amounts of light. Here, the light transmittance of the liquid is smaller than the light transmittance of the gas. Therefore, when the light passes through the liquid Lq, the light amount sensors 821 and 822 detect a small amount of light, and when the light passes through the gas Vp, the light amount sensors 821 and 822 detect a large amount of light. Therefore, the gas-liquid state of the first height L1 and the second height L2 can be determined from the detection values of the light quantity sensors 821 and 822.

  As in the second embodiment, the ECU 100 opens and closes the relief valve 69 depending on the height of the liquid level Lf. Thereby, it controls so that the liquid level Lf is maintained between 1st height L1 and 2nd height L2.

(Fourth embodiment)
As shown in FIG. 6, the liquid level detecting means 804 of the fourth embodiment is composed of two sets of light sources 811 and 812 having the same specifications, light quantity sensors 821 and 822, reflecting mirrors 831 and 832, and optical fibers 841 and 842. The
The optical fibers 841 and 842 are inserted into the return passage 66 from the fuel tank chamber 31 side. The distal end portion of the first optical fiber 841 is set to the first height L1, and the distal end portion of the second optical fiber 842 is set to the second height L2 that is lower than the first height L1.
Light emitted from the first light source 811 and the second light source 812 is reflected by the reflecting mirrors 831 and 832 and propagates through the cores (cores) of the first optical fiber 841 and the second optical fiber 842.

  The first light source 811 and the second light source 812 emit equivalent amounts of light. Here, the refractive index of light in the liquid is larger than the refractive index of light in the gas. Further, the refractive index of light in the optical fibers 841 and 842 that are solid is close to the refractive index of light in the liquid. Therefore, light is transmitted when the tip portions 851 and 852 of the optical fibers 841 and 851 are in the liquid Lq, and light is reflected when the tip portions 851 and 852 are in the gas Vp. The light quantity sensors 821 and 822 detect the quantity of reflected light. Therefore, the gas-liquid state of the first height L1 and the second height L2 can be determined from the detection values of the light quantity sensors 821 and 822.

  As in the second embodiment, the ECU 100 opens and closes the relief valve 69 depending on the height of the liquid level Lf. Thereby, it controls so that the liquid level Lf is maintained between 1st height L1 and 2nd height L2.

(Fifth embodiment)
As shown in FIG. 7, the liquid level detecting means 805 of the fifth embodiment includes two electrodes 861 and 862, an AC voltage source 87, a resistor 88 having a resistance value R, and three voltmeters 891 and 892. 893.
The electrodes 861 and 862 are, for example, copper plates. The electrodes 861 and 862 are installed in parallel in the return passage 66 at a certain distance. The AC voltage source 87 applies an AC voltage between the electrodes 861 and 862.

The voltmeters 891, 892, and 893 measure the power supply voltage Vo, the voltage Vr across the resistor 88, and the capacitance voltage Vc across the electrodes 861 and 862, respectively. The ECU 100 calculates the capacitance Cp between the electrodes 861 and 862 from these measured values using the following equations (2) and (3) (impedance measurement method). In addition, f in Formula (2) is an alternating current frequency.
Cp = Vv / (4πf · R · Vc ² ) (2)
Vv = {(− Vo + Vc + Vr) (Vo−Vc + Vr) (Vo + Vc−Vr)
(Vo + Vc + Vr)} ^1/2 Formula (3)

  Here, since the dielectric constant of the liquid is larger than the dielectric constant of the light of the gas, the height at which the liquid Lq comes into contact with the electrodes 861 and 862, that is, the higher the liquid level Lf, the larger the capacitance Cp. The lower the capacitance, the smaller the capacitance Cp. Therefore, based on the detection values of the voltmeters 891 to 893, the height of the liquid level Lf can be calculated in the range from the first height L1 to the second height L2.

  As in the second embodiment, the ECU 100 opens and closes the relief valve 69 depending on the height of the liquid level Lf. Thereby, it controls so that the liquid level Lf is maintained between 1st height L1 and 2nd height L2.

(Effects of the second to fifth embodiments)
In the above second to fifth embodiments, the liquid fuel remaining in the vaporization chamber 41 can be efficiently discharged based on detection information by various liquid level detection means using the physical property difference between the liquid and the gas. it can.

(Sixth embodiment)
Next, a sixth embodiment of the present invention will be described with reference to FIGS.
The fuel supply device 6 of the sixth embodiment includes a pressure sensor 90 as “internal pressure detection means” instead of the liquid level detection means 802 to 805 of the fuel supply devices 2 to 5 of the second to fifth embodiments. The pressure sensor 90 is provided in the vaporized fuel tank 40, detects the internal pressure of the vaporization chamber 41, and outputs it to the ECU 100. Further, the fuel supply device 6 of the sixth embodiment is provided with a relief valve 69 in the return passage 66 as in the fuel supply devices 2 to 5 of the second to fifth embodiments.

When the sub-injector 38 injects fuel into the gas chamber 41, the vaporization chamber internal pressure Pch rises and exceeds the upper threshold Pvo at time t0. Then, based on the detection signal from the pressure sensor 90, the ECU 100 opens the relief valve 69. Therefore, liquid fuel containing heavy liquid HC starts to be discharged to the return passage 66.
At this time, some time is required from the start of the discharge of the liquid fuel to the completion of the discharge due to the viscous resistance of the liquid pipe. During the discharge of the liquid fuel, while the liquid fuel remains in the vaporization chamber 41, the vaporization chamber internal pressure Pch is maintained at a substantially constant value due to the vapor pressure of the liquid fuel.

When the discharge of the liquid fuel is completed at time t1, the gas starts to be discharged from the vaporization chamber 41. Here, since the gas pipe viscous resistance is small, the vaporization chamber internal pressure Pch rapidly decreases.
When the vaporization chamber internal pressure Pch becomes less than the lower limit threshold Pvc at time t2, based on the detection signal from the pressure sensor 90, the ECU 100 considers that the liquid has been completely discharged and closes the relief valve 69.

  Thereby, the liquid fuel remaining in the vaporization chamber 41 can be efficiently discharged based on the detection information of the pressure sensor 90 as the internal pressure detecting means.

(Seventh embodiment)
Next, a seventh embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 10, the fuel supply device 7 of the seventh embodiment is the same as that of the sixth embodiment except that the pressure sensor is not provided. The ECU 100 opens the relief valve 69 at the same time as the fuel injection of the sub-injector 38 is completed, and the liquid fuel is discharged to the return passage 66. Here, the time from the end of the fuel injection to the completion of the liquid fuel discharge is measured many times, and the effective discharge time at which the liquid discharge is completed with a high probability is obtained from the data distribution. For example, if a value obtained by adding three times the standard deviation to the average value of the discharge time is defined as the effective discharge time, the liquid discharge is completed with a probability of 99.7% within the effective discharge time. Therefore, by closing the relief valve 69 after the effective discharge time from the end of fuel injection, the liquid fuel remaining in the vaporization chamber 41 can be discharged almost certainly.

  Thus, the liquid fuel remaining in the vaporization chamber 41 can be easily discharged without providing any liquid level detection means and internal pressure detection means.

(Other embodiments)
(A) In the first embodiment, the fuel pressure cylinder 73 is driven by the fuel injection pressure of the sub-injector 38. However, the cylinder may be driven by a fuel pressure other than the fuel injection pressure, or a hydraulic pressure such as hydraulic oil, and the edge as the detachment means may be operated. Or you may use the drive means by electromagnetic drive force, such as a solenoid. In this case, control by ECU becomes easy.

(A) In the second to fifth embodiments, the liquid level detection means 802 to 805 determine the gas-liquid state at two locations of the first height L1 and the second height L2 in the return passage 66. However, the liquid level detection means may determine the gas-liquid state at three or more heights.
For example, the gas-liquid state at the third height slightly higher than the second height is determined, and when the fluid is determined to be gas at the third height, the valve opening degree of the liquid discharge valve is reduced, and the discharge speed is You may control to slow down. As a result, from the first height to the third height, the liquid fuel can be discharged efficiently by increasing the discharge speed. In addition, by reducing the discharge speed from the third height to the second height, it is possible to prevent the discharge of gaseous fuel due to the delay in valve closing timing, and to further improve the separation accuracy between liquid fuel and gaseous fuel. Can do.

  (C) In the above embodiment, the vaporized fuel tank 40 is heated by the heat exchange member 50 adjacent to the cylinder block 11, and the fuel flowing through the branch passage 35 is heated by the heat exchange liquid Hw in the heating chamber 57. However, the vaporized fuel tank and fuel may be heated using other heat sources.

  As mentioned above, this invention is not limited to such embodiment, In the range which does not deviate from the meaning of invention, it can implement with a various form.

2, 3, 4, 5, 6, 7 ... fuel supply device,
10: Internal combustion engine,
11 ・ ・ ・ Cylinder block,
29 ・ ・ ・ Intake passage,
30 ... Fuel tank,
31 ... Fuel tank chamber,
32, 34 ... fuel passage,
33 ... Fuel pump,
35 ... branch passage,
36 ・ ・ ・ High pressure fuel pump,
37 ・ ・ ・ Main injector,
38... Sub-injector (vaporization chamber injection valve),
40 ・ ・ ・ Vaporized fuel tank,
41 ・ ・ ・ Vaporization chamber,
50 ・ ・ ・ Heat exchange member (vaporized fuel tank heating means),
65, 67 ... return passage member,
66 ... return path,
69 ・ ・ ・ Relief valve (liquid discharge valve),
80, 802, 803, 804, 805 ... Liquid level detection means,
90... Pressure sensor (internal pressure detecting means)
93 ... vaporized fuel passage,
99 ・ ・ ・ Internal combustion engine system,
100 ... ECU (valve opening / closing control means),
Hw ... heat exchange liquid (fuel heating means),
L1 ... first height,
L2 ... second height,
Lq ... liquid, liquid fuel,
Vp ... Gas, vaporized fuel,
Pch: Evaporation chamber internal pressure,
Pta: Fuel tank pressure,
Pvo ... upper threshold,
Pvc ... lower limit threshold.

Claims (5)

A fuel supply device (2, 3, 4, 5) for supplying vaporized fuel to an intake passage (29) of an internal combustion engine (10),
A vaporized fuel tank (40) that internally forms a vaporization chamber (41) for vaporizing liquid fuel;
A vaporization chamber injection valve (38) for injecting liquid fuel into the vaporization chamber;
A fuel pump (33) for pumping liquid fuel from a fuel tank chamber (31) in a fuel tank (30) provided on the lower side in the gravity direction of the vaporized fuel tank and supplying the liquid fuel to the vaporization chamber injection valve;
Return passage members (65, 67) forming return passages (66) for returning liquid fuel remaining in the vaporization chamber to the fuel tank chamber by gravity;
Liquid level detection means (80, 802, 803, 804, 805) for detecting whether the liquid level in the return passage is within a predetermined range;
A liquid discharge valve (69) that opens and closes based on detection information of the liquid level by the liquid level detection means, and that communicates or blocks the return passage;
Valve opening / closing control means (100) for controlling opening / closing of the liquid discharge valve;
With
The liquid level detection means is a gas-liquid state whether the fluid in the return passage is a gas or a liquid at a predetermined first height and a second height lower than the first height. Determine
The valve opening / closing control means includes
When the liquid level detection means determines that the fluid in the return passage is liquid at the first height, the liquid discharge valve is opened,
The fuel supply device, wherein the liquid discharge valve is closed when the liquid level detecting means determines that the fluid in the return passage is a gas at the second height. A fuel supply device (6) for supplying vaporized fuel to an intake passage (29) of an internal combustion engine (10),
A vaporized fuel tank (40) that internally forms a vaporization chamber (41) for vaporizing liquid fuel;
A vaporization chamber injection valve (38) for injecting liquid fuel into the vaporization chamber;
A fuel pump (33) for pumping liquid fuel from a fuel tank chamber (31) in a fuel tank (30) provided on the lower side in the gravity direction of the vaporized fuel tank and supplying the liquid fuel to the vaporization chamber injection valve;
A return passage member (65) forming a return passage (66) for returning liquid fuel remaining in the vaporization chamber to the fuel tank chamber by gravity;
An internal pressure detecting means (90) for detecting an internal pressure of the vaporizing chamber;
A liquid discharge valve (69) for communicating or blocking the return passage;
Valve opening / closing control means (100) for controlling opening / closing of the liquid discharge valve;
With
The valve opening / closing control means includes
When the internal pressure detection value detected by the internal pressure detection means exceeds a predetermined upper threshold, the liquid discharge valve is opened,
The fuel supply device, wherein the liquid discharge valve is closed when an internal pressure detection value detected by the internal pressure detection means becomes less than a predetermined lower limit threshold value. A fuel supply device (7) for supplying vaporized fuel to an intake passage (29) of an internal combustion engine (10),
A vaporized fuel tank (40) that internally forms a vaporization chamber (41) for vaporizing liquid fuel;
A vaporization chamber injection valve (38) for injecting liquid fuel into the vaporization chamber;
A fuel pump (33) for pumping liquid fuel from a fuel tank chamber (31) in a fuel tank (30) provided on the lower side in the gravity direction of the vaporized fuel tank and supplying the liquid fuel to the vaporization chamber injection valve;
A return passage member (65) forming a return passage (66) for returning liquid fuel remaining in the vaporization chamber to the fuel tank chamber by gravity;
A liquid discharge valve (69) for communicating or blocking the return passage;
Valve opening / closing control means (100) for controlling opening / closing of the liquid discharge valve;
With
The valve opening / closing control means includes
The fuel supply apparatus, wherein the vaporization chamber injection valve opens the liquid discharge valve for a predetermined period after injecting fuel into the vaporization chamber, and closes the liquid discharge valve after the predetermined period has elapsed.   The fuel supply apparatus according to any one of claims 1 to 3, wherein the vaporized fuel tank is heated by vaporized fuel tank heating means (50).   The fuel supply apparatus according to any one of claims 1 to 4, wherein the fuel supplied to the vaporization chamber injection valve is heated by a fuel heating means (Hw).

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