JP3994872B2 - Fuel injection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel injection device, and more particularly to a fuel injection device for liquefied gas fuel applied to an engine using liquefied gas as fuel.
[0002]
[Prior art]
In vehicle engines, there has been a social demand to use fuel instead of oil due to the recent growing interest in environmental issues. For example, diesel oil generally uses light oil as the fuel, but uses liquefied gas fuel such as dimethyl ether or liquefied natural gas (LPG) in consideration of fuel vaporization, combustibility, emission, etc. Has been proposed.
[0003]
As a fuel injection device for liquefied gas fuel, a common rail fuel injection device for diesel engines is generally applicable. A high pressure supply pump is connected to the fuel tank storing the liquefied gas fuel through a fuel supply pipe. The high-pressure supply pump is driven to rotate by the engine and discharges high-pressure fuel to the common rail. The high-pressure fuel is accumulated in the common rail to a pressure corresponding to a predetermined fuel injection pressure, and then injected from the injector. A feed pump is attached to the outlet side of the fuel tank.
[0004]
Since the liquefied gas fuel has a high saturated vapor pressure (for example, about 3 MPa at 90 ° C. for dimethyl ether), the fuel supply pressure to the high-pressure supply pump needs to be supplied at a predetermined pressure higher than that of light oil. For this reason, the feed pump sets the predetermined fuel supply pressure to about 2.5 to 3 MPa.
[0005]
Further, since the liquefied gas fuel has poor lubricity, the high-pressure supply pump to be used is a conventional high-pressure supply pump for light oil fuel having an oil lubrication structure instead of a fuel lubrication structure (Patent Document 1, etc.). In the conventional high-pressure supply pump disclosed in Patent Document 1, the fuel supplied by the feed pump is taken into a gallery chamber formed between the pump housing and the cylinder. The fuel in the gallery chamber is sealed by a sealing member such as an O-ring.
[0006]
[Patent Document 1]
JP-A 64-73166
[0007]
[Problems to be solved by the invention]
In the configuration according to the prior art, the liquefied gas fuel can be maintained in a liquid state by the predetermined fuel supply pressure during engine operation. However, when the engine is stopped, the predetermined fuel supply pressure cannot be maintained and decreases. Therefore, when the pressure of the supplied fuel falls below the saturated vapor pressure, a part of the fuel changes from liquid to gas. In general, no O-ring is resistant to both liquid and gas against liquefied gas fuel. In a conventional high-pressure pump, that is, a fuel injection device, a liquid can be sealed. However, in the case of gas, there is a problem that the gas leaks outside through the O-ring.
[0008]
The present invention has been made in view of such circumstances. Accordingly, an object of the present invention is to provide a fuel injection device capable of preventing leakage of liquefied gas fuel to the outside after the engine is stopped.
[0009]
[Means for Solving the Problems]
  According to claim 1 of the present invention, a cylinder that forms a gallery chamber between the pump housing and a plunger that is slidably accommodated in the cylinder is provided. In a fuel injection apparatus that compresses and discharges a guided fuel to a high pressure, a first seal that is resistant to liquid so as to surround the gallery chamber is provided between a pump housing and a cylinder that define the gallery chamber. A member is provided, and a second seal member that is resistant to gas is provided at a position opposite to the gallery chamber with the first seal member interposed therebetween.And
And between the 1st seal member and the 2nd seal member, it arrange | positions at the upper end part side of a pump housing, and covers the part of the said cylinder which protrudes from an upper end part, Between a shield member and a cylinder The gas reservoir is provided with a third seal member that is resistant to gas and is partitioned by a shielding member, a pump housing, and a cylinder.
[0010]
As a result, in the case where a part of the fuel changes from liquid to gas after the engine stops, even if the first seal member has insufficient resistance to gas, it is temporarily stored before high-pressure compression by the plunger. Of the fuel in the gallery chamber, the fuel changed from liquid to gas can be hermetically sealed by the second seal member.
[0015]
  MoreOf the present inventionAs claimed in claim 1The shielding member is disposed between the first sealing member and the second sealing member on the upper end side of the pump housing and covers a part of the cylinder protruding from the upper end portion, and between the shielding member and the cylinder. A gas reservoir is provided that includes a third seal member that is disposed and is resistant to gas, and is defined by a shielding member, a pump housing, and a cylinder.
[0016]
Accordingly, when it is desired to collect the gas leaked from the first seal member on the upper end side of the pump housing, the gas is disposed between the shielding member that covers a part of the cylinder and the shielding member and the cylinder. The leaked gas can be collected by the third seal member having resistance.
[0017]
  Of the present inventionClaim 2According to the present invention, the shielding member is provided with the leak recovery unit that guides the gas stored in the gas reservoir to the outside.
[0018]
Thereby, even if a part of the fuel becomes gas from the liquid and leaks from the first seal member, the gas can be stored in the gas reservoir, and the fuel in the gas state stored in the gas reservoir Can be returned to the fuel tank, for example, via the leak recovery section.
[0019]
  Of the present inventionClaim 3According toClaim 1 or claim 2The fuel injection device described inAnd as the fuelIn a fuel injection device for liquefied gas fuel that uses liquefied gas fuel,Gas reservoirA compressor is connected between the fuel tank and the fuel tank via a purge tank.
[0020]
As a result, even if a part of the fuel changes from liquid to gas after the engine is stopped, the fuel in the gaseous state collected in the gas reservoir can be decompressed or depressurized in the purge tank, and purged. The gaseous fuel that has been depressurized in the tank can be liquefied by using a compressor. As a result, by returning the fuel liquefied by the compressor to the fuel tank, it is possible to inject fuel as liquefied gas fuel.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
A specific embodiment of a fuel injection device of the present invention will be described with reference to the drawings.
[0022]
(First embodiment)
FIG. 1 is a cross-sectional view illustrating the configuration of the fuel injection device according to the present embodiment. FIG. 4 is a configuration diagram showing a schematic configuration of one example of the fuel injection device for liquefied gas fuel to which the fuel injection device according to the present embodiment is applied.
[0023]
As shown in FIG. 1, the fuel injection device is a device that discharges high-pressure fuel that accumulates pressure on a common rail (see FIG. 4) in a pressure-accumulation fuel injection system as a diesel engine fuel injection system (hereinafter referred to as a high-pressure pump). 3 is provided. The high-pressure pump 3 includes a pump housing 10 that holds each part, a camshaft 12 that is rotationally driven by an engine, a plunger 14 that is reciprocated by a plurality of cams 13 formed on the camshaft 12, and the plunger. A plurality of pump elements made up of a substantially cylindrical cylinder 15 that slidably holds 14 and an electromagnetic valve 30 screwed and fixed to the cylinder 15 at a position facing the upper end surface of the plunger.
[0024]
A cylinder 15 is mounted in the pump housing 10, and a plunger 14 is fitted in the cylinder 15 so as to be reciprocating and slidable. The plunger 14 has a substantially cylindrical shape. Note that leads such as notches are not provided at all on the outer peripheral surface of the plunger 14. A pump chamber 16 is formed by the upper end surface of the plunger 14, the inner peripheral surface of the cylinder 15, and the electromagnetic valve 30. A feed hole (not shown) communicating with the pump chamber is opened on the inner periphery of the cylinder 15. Furthermore, this feed hole is opened in the inner periphery of the gallery chamber 19 arrange | positioned at the outer peripheral side of a cylinder. A discharge hole 18 is opened above the inner peripheral surface where the feed hole is opened.
[0025]
The gallery chamber 19 is formed between the pump housing 10 and the cylinder 15 and constitutes a fuel reservoir. Low-pressure fuel is supplied to the gallery chamber 19 from a feed pump as a low-pressure supply pump (not shown) through the introduction pipe 60. The gallery chamber 19 is provided so as to be located at a corresponding portion between the inner peripheral surface of the pump housing 10 and the outer peripheral surface of the cylinder 15, and a hollow portion having a concave cross section is formed on the outer peripheral surface of the cylinder 15. Is provided. Further, the gallery chamber 19 is provided with a communication hole (not shown) in the lateral direction (substantially perpendicular to the paper surface of FIG. 1) so as to straddle the plurality of cylinders 15.
[0026]
A discharge valve 20 is attached to the cylinder 15, and the discharge valve 20 communicates with the pump chamber 16 through a discharge hole 18. The fuel pressurized in the pump chamber 16 pushes the valve body 21 of the discharge valve 20 against the biasing force of the return spring 22. As a result, the pressurized high pressure fuel is pumped into a common rail (not shown).
[0027]
An annular plate-shaped lower spring washer 24 is connected to the lower end of the plunger 14. Opposing to the lower spring washer 24, an annular plate-like upper spring washer 25 is disposed at the lower end of the cylinder 15. A plunger spring 26 is stretched between the lower spring washer 24 and the upper spring washer 25. The plunger spring 26 always urges the plunger 14 in a direction in which it retreats (downward movement in FIG. 1 among reciprocating movements). The lower spring washer 24 is engaged with the tappet 27. The tappet 27 is slidably inserted into the pump housing 10. The tappet 27 supports the cam roller 28 in a rotatable manner. The cam roller 28 is in sliding contact with the cam 13. Thereby, when the cam 13 is rotated by the rotation of the camshaft 12, the tappet 27 is reciprocated in the vertical direction in FIG. As a result, such movement of the tappet 27 is transmitted to the plunger 14 via the lower spring washer 24, and the plunger 14 reciprocates in the cylinder 15. The reciprocating stroke of the plunger 14 is determined by the height difference of the cam 13. Therefore, when the plunger 14 reciprocates in the cylinder 15, the outer circumferential surface of the plunger 14 opens and closes the feed hole, and the period in which the outer circumferential surface of the plunger 15 does not block the feed hole is stored in the gallery chamber 19. The low-pressure fuel is supplied to the pump chamber 16 through the feed hole.
[0028]
An electromagnetic valve 30 is screwed and fixed to the cylinder 15 at a position facing the upper end surface of the plunger 14. As shown in FIG. 1, one end of the electromagnetic valve 30 opens into the pump chamber 16. Further, the other end is subjected to the urging force of the spring 35 by the magnetic force of the solenoid 32 generated by energizing the coil 32 (not shown) via the terminal 33 and the body 32 formed with the low pressure passage 31 communicating with the low pressure side. Accordingly, the armature 36 sucked upward in FIG. 1 and the low pressure passage 31 communicate with each other by moving together with the armature 36 and detaching from the seat portion 37 formed at the opening to the pump chamber 16. A mushroom-like valve element 38 is provided as an outer valve to be shut off. The valve body 38 receives the fuel pressure in the pump chamber 16 as a pressing force in the valve closing direction. The solenoid valve 30 is energized at a predetermined timing after the outer peripheral surface of the plunger 14 closes the feed hole, so that the valve body 38 is seated on the seat portion 37 to set the pressurization start timing of the plunger 14. It is possible. The discharge amount to the common rail can be changed by controlling the energization timing to the electromagnetic valve 30. The low pressure passage 31 is configured to communicate with the gallery chamber 19.
[0029]
In order to control the solenoid valve 30, a rotating disk (not shown) having a number of protrusions corresponding to the number of engine cylinders is mounted coaxially with the camshaft 12, and is a known electromagnetic pickup facing the protrusion. A cam angle sensor (not shown) is arranged. Each time the protrusion passes near the cam angle sensor, a signal is sent to a control means (hereinafter referred to as ECU) (not shown). Further, a pair of disks and a cylinder discrimination sensor (not shown) are similarly attached to the camshaft 12 coaxially. This disc (hereinafter referred to as a cylinder discriminating disc) is formed with one projection, and therefore the ECU receives one signal per revolution from the cylinder discrimination sensor. From the signals of the cylinder discrimination sensor and the cam angle sensor, the ECU can accurately receive the bottom dead center signal of the specific cylinder of the pump 3 corresponding to the engine. Note that information such as the engine speed and load related to the engine operating state is input to the ECU from, for example, an engine speed sensor (not shown) or a load sensor (not shown). Then, the ECU outputs a control signal to an injector (not shown) so that the optimal injection timing and injection amount determined according to the engine state determined by these signals. At the same time, the ECU outputs a control signal to the electromagnetic valve 30 of the high-pressure supply pump 3 so that the fuel injection pressure is optimized according to the load and the rotational speed.
[0030]
Here, a liquefied gas fuel such as dimethyl ether (DME) or liquefied natural gas (LPG) is used as the fuel used in the present embodiment. Since the liquefied gas fuel has poor lubricity, the cam chamber 29 through which the camshaft 12 is inserted has an oil lubrication structure in which lubricating oil is stored so that the lubricating oil adheres to or is immersed in the cam 13. .
[0031]
The liquefied gas fuel has a relatively high saturated vapor pressure. For example, in the case of dimethyl ether, when the temperature is 90 ° C., the saturated vapor pressure reaches about 3 MPa. The vapor pressure characteristic of dimethyl ether gradually increases as the temperature rises to about 0.5 MPa at 0 ° C. and about 1 MPa at 40 ° C.
[0032]
Hereinafter, the liquefied gas described in the present embodiment is dimethyl ether (DME). Therefore, the pressure of the low pressure fuel supplied to the gallery chamber 19 of the high pressure supply pump 3 by the feed pump is set to a predetermined fuel supply pressure in the range of about 2.5 to 3 MPa. As a result, the low pressure fuel can be set substantially higher than the saturated vapor pressure by the predetermined fuel supply pressure, so that dimethyl ether can be maintained in a liquid state.
[0033]
However, in the case of a vehicle engine, for example, when the engine is stopped, the ignition key is turned off and the engine is stopped. Since the high pressure supply pump 3 is rotationally driven by the engine, when the engine is stopped, the operation of compressing the low pressure fuel to the high pressure by the reciprocating motion of the plunger 14 of the high pressure supply pump 3 is also stopped. Regardless of whether the feed pump is an electric pump driven by energization or is driven to rotate by the engine, if the ignition key is turned off and the power supply from the battery power supply is stopped, the low pressure fuel is supplied to the predetermined fuel. The supply to the gallery chamber 19 is stopped at the supply pressure.
[0034]
When the outer peripheral surface of the plunger 14 closes the feed hole, that is, when the plunger 14 is in the pressure feeding process, the gallery chamber 19 has a predetermined fuel supply pressure immediately before the feed pump stops. When the plunger 14 is pumped and the solenoid valve 30 is opened, the high pressure fuel in the pump chamber immediately before the solenoid valve 30 is opened is returned to the gallery chamber 19 via the low pressure passage 31. In some cases, the fuel pressure in the gallery chamber 19 temporarily becomes higher than a predetermined fuel supply pressure.
[0035]
When the outer peripheral surface of the plunger 14 does not block the feed hole, that is, when the plunger 14 is in the suction process, the gallery chamber 19 communicates with the pump chamber. It becomes a predetermined fuel supply pressure immediately before the feed pump stops. At this time, the discharge valve 20 is closed by the urging force of the return spring 22 and therefore does not communicate with the common rail side.
[0036]
Thus, regardless of whether the feed hole is blocked or not, immediately after the engine is stopped, the fuel pressure in the gallery chamber 19 is the predetermined fuel supply pressure immediately before the feed pump stops. However, since the feed pump generally does not have a check valve, the fuel pressure in the gallery chamber 19 may gradually decrease. Even when a check valve is arranged in the middle of the fuel passage from the fuel tank via the feed pump to the gallery chamber 19, for example, when the engine is stopped, the feed pump is stopped by turning off the ignition key. There may be a difference between the timing and the timing when the high-pressure supply pump 3 is stopped by the rotational drive of the engine. For example, the feed pump may stop when the plunger 14 closes the feed hole, and then the high-pressure pump 3, that is, the plunger 14 may stop without closing the feed hole. In this case, the fuel pressure in the gallery chamber 19 decreases by the amount of fuel guided from the gallery chamber 19 into the pump chamber 16.
[0037]
On the other hand, in this embodiment, as shown in FIG. 1, the pump housing 10 that partitions the gallery chamber 19 and the cylinder 15 are resistant to liquid so as to surround the gallery chamber 19. First seal members 41 and 42 are provided. Furthermore, a second seal member 43 that is resistant to gas is provided at a position opposite to the gallery chamber 19 side with the first seal member 42 interposed therebetween. The second seal member 43 is disposed between the pump housing 10 and the cylinder 15 similarly to the first seal member. Accordingly, the first seal members 41 and 42 are formed of a material having insufficient resistance to the gas. For example, even if the gas may pass through the first seal member, the gallery chamber 19 may be used. It is possible to hermetically seal the fuel that has changed from liquid to gas among the fuels inside by the second seal member.
[0038]
In addition, as a kind of 1st sealing member and 2nd sealing member, as long as cross-sectional shapes, such as an O-ring or a square ring, have a shape suitable for a seal | sticker, what kind of thing may be sufficient. Hereinafter, the first seal members 41 and 42, the second seal member, and the third seal member, which will be described later, will be described as O-rings.
[0039]
Furthermore, as materials for the first O-rings 41 and 42 and the second O-ring 43, for example, both of them may be made of nitrile rubber, and the first seal members 41 and 42 and The second seal member 43 has a different composition for forming nitrile rubber. That is, the first O-rings 41 and 42 use nitrile rubber prepared by adjusting the nitrile rubber to a composition suitable for airtightness of the liquid of dimethyl ether as a fuel, that is, resistant to the liquid. The second O-ring 43 uses nitrile rubber adjusted to a composition suitable for gas tightness, that is, resistant to gas. Note that the rubber material itself may be changed such that the first O-rings 41 and 42 are fluororubber and the second O-ring 43 is nitrile rubber.
[0040]
Here, a second seal member 43 that is resistant to gas is provided at a position opposite to the gallery chamber 19 side with at least one of the first O-rings 41 and 42 interposed therebetween. Any may be used. As shown in FIG. 1, when the lower part of the cylinder 15 is inserted and assembled in the pump housing 10, it is preferable to arrange the second O-ring 43 on the upper end side of the pump housing 10. As a result, the second O-ring is disposed downstream of the O-ring 42 on the side of the first O-rings 41 and 42 whose downstream side is open to the atmosphere, so that the dimethyl ether in the gaseous state is efficiently airtight. It is possible to hold it.
[0041]
Furthermore, in the present embodiment, as shown in FIG. 1, a gas reservoir 51 defined by the pump housing 10 and the cylinder 15 is provided between the first O-ring 42 and the second O-ring 43. It has been. As a result, a space having a relatively large volume can be formed between the first O-ring 42 and the second O-ring 43. As a result, when a relatively small amount of gas leaks through the first O-ring 42, the gas can be decompressed. As a result, as a characteristic of the O-ring used for the second O-ring 43, there is a ripple effect that makes it possible to use an inexpensive O-ring having a relatively low limit pressure resistance.
[0042]
Furthermore, in this embodiment, the gas reservoir 51 is connected to the gas passage 52 as shown in FIG. Further, the gas passage 52 is connected to a leak recovery unit 53 that can be connected to external piping. That is, the gas reservoir 51 communicates with the leak recovery unit 53. As a result, even if a part of the dimethyl ether as the fuel is changed from liquid to gas and leaks from the first O-ring 42, the gas can be stored in the gas reservoir 51 and stored in the gas reservoir 51. It is possible to return the gaseous dimethyl ether to the fuel tank via the leak recovery unit 53.
[0043]
Furthermore, it is preferable that the gas passage 52 and the leak recovery part 53 are formed in the cylinder 15. Thereby, as shown in FIG. 1, when the upper part of the cylinder 15 protrudes from the upper end part of the pump housing 10, it is easy to secure the thick part of the cylinder 15 that forms the gas passage 52 and the leak recovery part 53. As a result, productivity can be improved. In addition, when the thick part which forms the leak collection part 53 in the pump housing 10 can be ensured, the leak collection part 53 may be formed in the pump housing 10.
[0044]
An embodiment in which the high-pressure supply pump 3 described above is applied to a fuel injection device for liquefied gas fuel using dimethyl ether as fuel will be described with reference to FIG. In FIG. 4, 2 is a feed pump, 3 is a high-pressure supply pump, and 4 is a common rail. Since these have been described in the above embodiment, description thereof will be omitted.
[0045]
The fuel tank 1 stores dimethyl ether in a saturated vapor pressure state or a liquefied state. A feed pump 2 is attached to the outlet of the fuel tank 1. Note that the feed pump 2 may be installed in the fuel tank 1. Hereinafter, the feed pump 2 will be described as an electric type driven by a motor or the like.
[0046]
The feed pump 2 is connected to the high-pressure supply pump 3 and supplies low-pressure fuel to the gallery 19 through the introduction pipe 60. Next, the high pressure supply pump 3 is connected to the common rail 4 through the discharge valve 20 via the high pressure fuel injection pipe. In the common rail 4, high-pressure fuel discharged by the high-pressure supply pump 3 is accumulated at a so-called common rail pressure corresponding to a predetermined fuel injection pressure. An injector 5 attached to each cylinder of the engine is connected to the common rail 4 via a high-pressure fuel pipe. The injector 5 is supplied with high-pressure fuel having a common rail pressure accumulated in the common rail 4 and injects the fuel into the combustion chamber of the cylinder.
[0047]
Here, in the present embodiment, as shown in FIG. 4, the gaseous dimethyl ether stored in the leak recovery unit 53 of the high-pressure supply pump 3 is returned to the fuel tank 1. Further, a compressor 7 is connected between the leak recovery unit 53 and the fuel tank 1 via a purging tank 6. This purging tank 6 functions as a pressure release storage tank.
[0048]
As a result, even if part of the fuel changes from liquid to gas after the engine is stopped, the fuel in the gaseous state collected in the gas reservoir 51 can be decompressed, that is, depressurized by the purge tank 6. Further, the gaseous fuel depressurized by the purge tank 6 can be liquefied by using the compressor 7. As a result, by returning the fuel liquefied by the compressor 7 to the fuel tank 1 again, it is possible to inject the fuel as liquefied gas fuel without wasteful use such as being discharged outside.
[0049]
(Second Embodiment)
Hereinafter, other embodiments to which the present invention is applied will be described. In the following embodiments, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and description thereof will not be repeated.
[0050]
In the second embodiment, the space of the gas reservoir 51 described in the first embodiment is replaced with a stepped portion 10 a formed in the pump housing 10, as shown in FIG. You may form by the formed groove part 15a. FIG. 2 is a cross-sectional view illustrating the configuration of the fuel injection device according to the present embodiment. Also by this, the same effect as that of the first embodiment can be obtained.
[0051]
(Third embodiment)
In the third embodiment, when it is desired to collect the gas leaked from the first O-ring 42 on the upper end side of the pump housing 10, as shown in FIG. 3, the shielding member 55 and the gas are resistant to the gas. The third O-rings 44 and 45 are provided. FIG. 3 is a cross-sectional view illustrating the configuration of the fuel injection device according to the present embodiment.
[0052]
As shown in FIG. 3, the shielding member 55 is configured to cover a part of the cylinder 15 protruding from the upper end portion of the pump housing 10. One end of the shielding member 55 is disposed on the upper end side of the pump housing 10. A second O-ring 43 is disposed between one end of the shielding member 55 and the upper end portion of the pump housing 10. On the other hand, the other end of the shielding member 55 is disposed on the outer peripheral side of the upper portion of the cylinder 15. Third O-rings 44 and 45 are disposed between the other end of the shielding member 55 and the outer periphery of the upper portion of the cylinder 15. Thereby, the gas reservoir 51 defined by the shielding member 55, the upper end of the pump housing 10, and the outer periphery of the upper portion of the cylinder 15 can be formed.
[0053]
Thereby, the shielding member 55 that covers a part of the cylinder 15, and the third O-rings 44 and 45 that are disposed between the shielding member 55 and the outer periphery of the upper portion of the cylinder 15 and are resistant to gas, It is possible to collect the gaseous fuel that has leaked from the first O-ring.
[0054]
The gas reservoir 51 constitutes a space for storing gaseous fuel disposed between the first O-ring 42 and the second O-ring 43. Thereby, the storage space which has a comparatively big volume is securable.
[0055]
Furthermore, in this embodiment, as shown in FIG. 3, it is preferable that the shielding member 55 includes a piping portion 55a that can be connected to the outside. Thereby, the fuel in the gas state stored in the gas reservoir 51 can be returned to the fuel tank 1 via the piping 55a.
[0056]
The pipe 55a constitutes a leak recovery unit that can be connected to the outside such as a fuel tank.
[0057]
In the present embodiment described above, the structure of the high-pressure supply pump 3 is such that the element composed of the plurality of plungers 14 and the cylinder 15 described in the present embodiment is arranged in the extending direction of the camshaft 12 corresponding to the cam 13. Not only those that can be distributed to a plurality of cylinders by a single plunger and cylinder, but any other pressure-applying member such as a cam that reciprocally moves the plunger and compresses fuel at high pressure can be used. It may be the structure.
[0058]
In the fuel injection device for liquefied gas fuel described in this embodiment, when the fuel is collected in the gas reservoir 51 and returned to the fuel tank 1 through the leak recovery unit 53, the compressor 7 compresses and compresses the fuel in the gaseous state. However, the configuration in which the fuel is liquefied by cooling the gaseous fuel using a cooler may be used.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a configuration of a fuel injection device according to a first embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a configuration of a fuel injection device according to a second embodiment.
FIG. 3 is a cross-sectional view illustrating a configuration of a fuel injection device according to a third embodiment.
FIG. 4 is a configuration diagram showing a schematic configuration of a fuel injection device for liquefied gas fuel to which the fuel injection device of the present invention is applied.
[Explanation of symbols]
1 Fuel tank
2 Feed pump (low pressure supply pump)
3 High-pressure supply pump
4 Common rail
5 Injector
6 Purge tank
7 Compressor
10 Pump housing
10a Stepped part
14 Plunger
15 cylinders
15a Groove
16 Pump room
19 Gallery room
41, 42 First O-ring (first seal member)
43 2nd O-ring (second seal member)
44, 45 Third O-ring (third seal member)
51 Gas reservoir
52 Gas passage
53 Leak recovery section
55 Shielding member
55a Piping section (leak recovery section)

Claims (3)

A cylinder that forms a gallery chamber between the pump housing and a plunger that is slidably accommodated in the cylinder. The fuel guided from the gallery chamber to the cylinder by the reciprocating movement of the plunger is pressurized. In a fuel injection device that compresses and discharges
Between the pump housing and the cylinder that partitions the gallery chamber, a first seal member that is resistant to liquid is provided so as to surround the gallery chamber, and
A second seal member having resistance to gas is provided at a position opposite to the gallery chamber side with the first seal member interposed therebetween ,
And between the said 1st sealing member and the said 2nd sealing member, the shielding member which is arrange | positioned at the upper end part side of the said pump housing, covers a part of said cylinder which protrudes from the said upper end part, and the said shielding A third seal member disposed between the member and the cylinder and having resistance to gas; and a gas reservoir section defined by the shielding member, the pump housing, and the cylinder is provided. A fuel injection device characterized by the above. 2. The fuel injection device according to claim 1, wherein the shielding member is provided with a leak recovery unit that guides the gas stored in the gas reservoir to the outside . The fuel injection device according to claim 1 or 2, wherein a liquefied gas fuel is used as the fuel.
A fuel injector for liquefied gas fuel, wherein a compressor is connected between the gas reservoir and the fuel tank via a purge tank .

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