This application is based upon and claims the benefit of priority of Japanese Patent Applications No. 2004-302576 filed on Oct. 18, 2004, and No. 2005-222706 filed on Aug. 1, 2005, the contents of which are incorporated herein by reference.
The present invention relates to a gaseous fuel injector to inject a high-pressure gaseous fuel directly into a cylinder of an internal combustion engine.
Current development of the next-generation vehicles places prime importance on clean emission gas and CO2 emission decrease. Conventional liquid fossil fuel combustion has an improvement ceiling to achieve these targets. Gaseous fuels such as gaseous fossil fuel (natural gas, petroleum gas, etc.) and hydrogen gas, which are expected to burn more efficiently, can substitute for the liquid fossil fuel. Then, gaseous fuel engines, which use the above-described gaseous fuels, are under development, and a part of which is coming into actual use.
Conventionally, it is difficult to inject enough amount of gaseous fuel in direct injection engines, because of a small density of the gaseous fuel, to cause a shortage of an output power of the engine. It is possible to inject enough amount of gaseous fuel in spark ignition engines, in which pre-mixture time is relatively long, however the injected gaseous fuel has a relatively small momentum and cannot be mixed enough with intake air, causing issues of unburnt fuel emission and output power shortage. In compression ignition engines, it is further difficult to inject enough amount of gaseous fuel in a short time and to mix the gaseous fuel with intake air, causing issues of unburnt fuel emission and output power shortage.
Thus, various technologies are in studies to solve the output power shortage and to reduce the unburnt fuel emission. For example, a technology for injecting two kinds of fuel is disclosed in JP-2003-232234-A, another technology to operate two fuel injections for one combustion is disclosed in JP-2000-345884-A, and a technology using two fuel injection valves is disclosed in JP-2004-68762-A.
JP-2003-232234-A discloses a fuel supply control apparatus that selectively or simultaneously supplies a liquefied petroleum gas (LPG) and liquid fuel such as gasoline to so-called a “bi-fuel internal combustion engine”. The apparatus has a first fuel supply path to supply LPG and a second fuel supply path to supply the liquid fuel. In switching the engine to a mode driven only with LPG, the apparatus supplies both of LPG and liquid fuel to the engine, so that an air-fuel ratio is prevented from excessive lean not to occur an accidental fire and not to spoil a drivability of the engine and a vehicle.
JP-2000-345884-A discloses a control apparatus for an internal combustion engine that injects gaseous fuel directly into a combustion chamber of an engine. The control apparatus selects a first fuel injection performed only in a compression stroke or a second fuel injection performed both in an induction stroke and in a compression stroke in accordance with a required injection time. That is, the gaseous fuel is injected only in the compression stroke if the required injection time is short. The gaseous fuel is injected not only in the compression stroke but also in the induction stroke by a difference between the required injection time and injection operable time in the compression stroke, to prevent the air induction amount into the combustion chamber from shortage and to prevent a performance of the internal combustion engine from decreasing.
JP-2004-68762-A discloses a fuel supply device provided with a pair of in-cylinder fuel injection valve (or an in-cylinder fuel injection valve and in-intake passage fuel injector) to inject gaseous fuel directly into a cylinder of an engine. A first fuel injection valve has a relatively small injection ratio, and a second fuel injection valve has a relatively large injection ratio. The gaseous fuel is injected from the first fuel injection valve when a requited fuel amount is smaller than a predetermined amount, and injected from the second fuel injection valve when the required fuel amount is larger than the predetermined amount. Thus, intake air charging efficiency is prevented from decreasing when the required fuel amount becomes large, to secure a large output power of the engine.
However, the fuel supply control apparatus disclosed in JP-2003-232234-A is not for an engine that mainly uses gaseous fuel. The bi-fuel injection disclosed in JP-2003-232234-A improves drivability by controlling the injections of LPG and liquid fuel in accordance with a driving condition of the engine. However, a vaporization prevention of LPG increases a driving region driven by liquid fuel. Further, the fuel supply control apparatus requires two large fuel tanks, two fuel supply systems and two fuel injection valves respectively for LPG and liquid fuel. This construction increases dimensions of the fuel supply control apparatus. The fuel supply control apparatus is for injecting LPG in its liquid phase, and JP-2003-232234-A does not disclose an apparatus for injecting a required amount of gaseous fuel in a short time.
The control apparatus disclosed in JP-2000-345884-A is to perform an effective combustion by operating the fuel injection in the compression stroke. The control apparatus does not enable to inject a required amount of gaseous fuel in a short time. When the injection amount is large, the required injection time becomes long and the gaseous fuel is injected also in the induction stroke, and the gaseous fuel with large volume decreases an air intake amount. Thus, an output power increase by the control apparatus is limited, just as preventing the output power from decreasing.
JP-2004-68762-A discloses the fuel injection control by two in-cylinder injection valves having relatively small injection ratio and relatively large injection ratio, however, does not disclose a specific constructions thereof. In the range in which the required fuel injection amount is large, it is possible to inject the gaseous fuel from both of the two in-cylinder fuel injection valves, however, it requires two in-cylinder injection valves and two fuel supply systems to make the construction of the apparatus complex. Further, the apparatus limits an arrangement to promote a mixture of the injected spray, to increase a manufacturing cost.
As described above, under current circumstances, it is difficult to improve an output power and to decrease an unburnt fuel emission simultaneously in the fuel injector that mainly injects high-pressure gaseous fuel. Further, a large amount injection of the gaseous fuel can affect injections in other cylinders of the engine.
The present invention is achieved in view of the above-described issues, and has an object to provide a fuel injector for injecting high-pressure gaseous fuel into a combustion chamber of an internal combustion engine, which has small dimensions and a large output power to inject a large amount of the gaseous fuel and decreases unburnt fuel emission by promoting a mixture with intake air. Another object is to provide a small and practical gaseous fuel injector that can be installed regardless of the constructions and shapes of an intake and discharge valves of the engine, and can inject the gaseous fuel without affecting fuel injections in other cylinders.
The fuel injector has: an inlet port through which the high-pressure gaseous fuel is supplied; an injection hole through which the high-pressure gaseous fuel is injected; a gaseous fuel supply path that extends from the inlet port to the injection hole to flow the high-pressure gaseous fuel therethrough; a needle that opens or closes the injection hole; and an actuator that actuates the needle. The gaseous fuel supply path is provided with a first volume increase portion at which a cross-sectional area of the gaseous fuel supply path rapidly increases as going from the injection hole toward the inlet port.
Other objects, features and advantages of the present invention will be appreciated, as well as methods of operation and the function of the related parts, from a study of the following detailed description, the appended claims, and the drawings, all of which form a part of this application. In the drawings:
A fuel injector according to a first embodiment of the present invention is described in the following referring to
The fuel injector 1 according to the first embodiment is for injecting high-pressure gaseous fuel directly into a cylinder of a multicylinder compression ignition engine. The fuel injector 1 is provided for each cylinder's combustion chamber.
The fuel injector 1 according to the first embodiments uses the operating oil to perform an on/off control of the pressure in the control chamber 2 in addition to the high-pressure gaseous fuel that is injected. A pressure of the operating oil in the control chamber 2 performs a valve-closing operation of the needle 31 as shown in
A basic construction of the fuel injector 1 and the operating oil supply path therein are described referring to
The injector body 5 has a cylindrical shape, and a control piston 52 is slidably installed in a cylinder hole in the injector body 5. The control chamber 2 is formed at an upper end side of the control piston 52. In a cylinder wall of the injector body 5 at a side of the control piston 52 are formed two operating oil passages that extend in an axial direction (vertical direction in
In the nozzle 3, a longitudinal hole, which is formed in the nozzle body 32 in its longitudinal direction, slidably supports a needle 31 having a stepped circumferential face. An upper end portion of the needle 31 is coupled to a lower end portion of the control piston 52 so that the needle 31 and the control piston 52 integrally move with each other. A return spring 53, which is disposed in a spring room 54 formed around an outer circumference of the lower end portion of the control piston 52, urges the needle 31 downward. A lower end of the high-pressure oil passage 22 is communicated with a lubrication passage 34 to supply the operating oil as lubricating oil to a large diameter guide portion 311 of the needle 31. A lower end of the oil return passage 25 is communicated with the spring room 54 to recover the leakage oil from respective portions in the fuel injector 1 and drain the leakage oil out of the oil outflow pipe 26.
The plate member 21 is installed inside the upper end opening of the injector body 5 to block the cylinder hole in which the control piston 52 slides. The control chamber 2 is defined by an upper end face of the control piston 52, an inner circumferential face of the cylinder hole and a depressed portion of the plate member 21 that is formed at a center on a lower end face of the plate member 21. The control chamber 2 is communicated with a high-pressure passage 24 that is branched from the high-pressure oil passage 22 via an inlet aperture 2a at all times. The pressure in the control chamber 2 acts downward on the needle 31 via the control valve 52. The control chamber 2 is communicated also with the oil return passage 25 via an outlet aperture 2b. The electromagnetic valve 6 connects and interrupts the communication between the control chamber 2 and the oil return passage 25 to increase and decrease the pressure in the control chamber 2.
The electromagnetic valve 6 has a solenoid body 61, a cylinder-shaped solenoid 64 installed in the solenoid body 61 and a control valve 63. The control valve 63 has: an armature that has a T-shaped cross-section and faces a lower end face of the solenoid 64; and a ball valve that is supported in a hemispherical depression formed at a leading end portion of the armature. A low-pressure passage 65 is provided around the leading end portion of the armature to communicate the outlet aperture 2b with the oil return passage 25. When the control valve 63 is not energized, a spring 66 that is disposed in the solenoid 64 urges the control valve 63 downward so that the ball valve blocks the outlet aperture 2b of the control chamber 2.
In order to inject a large amount of gaseous fuel having relatively small density in a short time, it is desirable that the gaseous fuel supply path is provided with a plurality of the volume increase portions in which a cross-sectional area of the gaseous fuel supply path rapidly increases. In the first embodiment, a thick-walled portion of the cylinder wall of the injector body 5 has a cavity therein to provide the gaseous fuel supply path between the gas inflow pipe 44 and the high-pressure gas passage 41 with an injector chamber (a second volume increase portion) 43. Further, as described above, the stem 312 of the needle 31 upstream the injection holes 37 and the nozzle body 32 around the stem 312 provide the nozzle chamber 35 therebetween. Furthermore, in order to supply the high-pressure gaseous fuel fast to the nozzle chamber 35, the nozzle body 32 is provided with a plurality of feed passages 36a, 36b that are connected to the high-pressure gas passage 41, so that a large amount of the high-pressure gaseous fuel can be supplied to the nozzle chamber 35.
When a valve-open command by a control unit (not shown) loads a driving current in the solenoid 64 of the electromagnetic valve 6 to lift up the control valve 63 against a spring force of the spring 66, the outlet aperture 2b of the control chamber 2 opens. By the valve-open of the control valve 63, the high-pressure gaseous fuel in the control chamber 2 is discharged via the outlet aperture 2b and the low-pressure passage 65 to the oil return passage 25. The outlet aperture 2b, which regulates a outflow of the high-pressure gaseous fuel from the control chamber 2 to the low-pressure passage 65, has a cross-sectional area larger than that of the inlet aperture 2a, which regulates an inflow of the high-pressure gaseous fuel from the high-pressure passage 24 into the control chamber 2, so that the valve-open of the control valve 63 decreases the pressure in the control chamber 2.
When the pressure in the control chamber 2 decreases, a force to push down the control piston 52 and the needle 31 decreases, and the force of the high-pressure gaseous fuel in the nozzle chamber 35 to push up the needle 31 exceeds a resultant force of the return spring 53 and the operating oil in the control chamber 2 to push down the needle 31. Accordingly, the needle lifts up so that the seat portion 38 moves off the nozzle body 32, and the high-pressure gaseous fuel in the nozzle chamber 35 flows to the sac 39 to be injected out of the injection holes 37 into the combustion chamber of the engine. As described above, by the construction provided with the control chamber 2 that applies backpressure on the needle 31 so that the high-pressure operating oil actuates the control piston 52, a relatively large driving force is generated to actuate the needle 31 speedily.
A detailed construction of the nozzle 3 is described in the following referring to
As described above, the nozzle chamber 35 is provided in a lower half portion of the nozzle body 32, in which an outer diameter of the needle 31 is decreased and an inner diameter 322 of the nozzle body 5 is extended radially outward, to increase a volume of the high-pressure gaseous fuel accumulated therein. Specifically, the inner diameter of the lower half portion of the nozzle body 5 is larger than the inner diameter of the sliding portion 311 of the needle 31. The outer diameter of the stem 312 of the needle 31 is smaller than the maximum outer diameter of the leading end portion of the needle 31 (for example, the outer diameter of the stem 312 is approximately as small as the outer diameter at the seat portion 38).
Further, the needle 31 has a needle chamber hole 315 that is formed in its stem 312 in its longitudinal direction. The nozzle chamber opens to the nozzle chamber 35 at communication holes 313, 314 that are provided at an upper and an lower end portions of the stem 312. Furthermore, the nozzle body 32 may be provided with an additional chamber 321 that is communicated with the upper end portion of the nozzle chamber 35. The needle chamber hole 315 and the additional chamber 321 serve a volume increase of the high-pressure gaseous fuel accumulated in the nozzle 3. Further volume increase means may be incorporated in the nozzle 3 to increase the volume of the high-pressure gaseous fuel accumulated in the nozzle 3.
It is desirable that a total cross-sectional area of the gaseous fuel supply path in the volume increase portion in the nozzle body 32 (a summation of a cross-sectional area of the nozzle chamber 35 and a cross-sectional area of the needle chamber hole 315) is between once to ten times a difference between a cross-sectional area of the stem 312 and the cross-sectional area of the needle chamber hole 315 ((cross-sectional area of the stem 312)−(cross-sectional area of the needle chamber hole 315)). A large volume of the nozzle chamber 35 secures a large amount of the high-pressure gaseous fuel just upstream the injection holes 37. In order to secure an enough amount of the high-pressure gaseous fuel in the fuel injector 1 for each fuel injection, it is desirable that the injector chamber 43, which is provided on the way of the high-pressure gas passage 41, has a large volume on the order of several square centimeters.
In the first embodiment, two feed passages 36a, 36b are formed in the nozzle body 32 to supply the high-pressure gaseous fuel from the high-pressure gas passage 41 to the nozzle chamber 35. The feed passages 36a, 36b are formed at the side of the guide portion 311 of the needle 31 and open to the upper end portion of the nozzle chamber 35. More than two feed passages 36a, 36b are necessary to increase the volume of the high-pressure gaseous fuel in the nozzle body 32 and to allocate large inner diameters for them.
An amount of the high-pressure gaseous fuel that is supplied to the internal combustion engine must have accuracy in accordance with a target amount. The pressure of the high-pressure gaseous fuel in the gaseous fuel supply path in a leading portion region of the injector 1 (especially in the nozzle body 32) is required to be within a specific margin of fluctuation over a time from an injection start to an injection stop. An excessively large fluctuation of the pressure of the high-pressure gaseous fuel occurs an uneven fuel injection amount. In the present invention, the gaseous fuel supply path in the nozzle 3 is provided with the volume increase portion so that the fuel injection amount per one injection in intermittent injections, which repeats injection starts and injection stops, corresponds to the target amount in respective operation ranges. The volume increase portion has dimensions in view of the one injection volume.
The above-described range between once and ten times is determined in view of the conditions below. The injector 1 according to the present invention is for the vehicles of the next generation and has dimensions as follows. As shown in
In the above-described conditions, the minimum ratio (once) in the above-described range is determined to secure a required injection performance to inject the high-pressure gaseous fuel. The maximum ratio (ten times) in the above-described range serves the large volume increase portion, and is determined in view of the limited size and material strength of the components of the injector 1. The range between once and ten times corresponds to a range between 0.2 times and 0.5 times in conventional fuel injectors.
In the nozzle body 32 is formed the lubrication passage 34 at the side of the guide portion 311 of the needle 31 to open to the longitudinal hole in which the guide portion 311 slides. The guide portion 311 is provided with a plurality of lubrication grooves on its outer circumferential face, into which the high-pressure operating oil is supplied from the high-pressure oil passage 22 via the lubrication passage 34 to lubricate sliding surfaces on the guide portion 311 and the nozzle body 32. The high-pressure gaseous fuel in the nozzle body 32 pushes the operating oil, which lubricates the guide portion 311, upward from the guide portion 311 to leak into the spring room 54 in the injector body 5 and to be recovered through the oil return passage 25 to the oil outflow pipe 26.
An example to form the injector chamber 43 in the injector device 1 is described referring to the
Alternative examples to form the injector chamber 43 in the injector device 1 are described referring to the
In the first embodiment, a plurality of the volume increase portions (chambers) provided in the gaseous fuel supply path enable to secure a required injection amount and to keep a large injection pressure. Constructions and functions of respective chambers are described in the following with reference to
At the injection start by a valve-open of the needle 31 shown in
(Pressure wave)=(Gas density)×(Sound velocity)×(Outflow speed) (1)
That is, the pressure wave is transmitted leftward in
(Reflection coefficient)=(A1−A2)/(A1+A2) (2)
That is, the pressure wave that is smaller than the initial pressure is reversed between positive and negative by the nozzle chamber 35 and reflected to the seat portion 38 at a pressure increased from the initial pressure by a product of the formulae (1) and (2). Thus, an actual injection pressure at the injection start time is prevented from decreasing and a high-pressure injection is kept.
A further continuous fuel injection decreases the initial pressure by the injection of the high-pressure gaseous fuel in the nozzle chamber 35. The injector chamber 43 having a large volume and disposed upstream the nozzle chamber 35 continuously supplies the high-pressure gaseous fuel to refills the nozzle chamber 35. Thus, the pressure in the nozzle chamber 35 is prevented from decreasing. The volume of the injector chamber 43 around 2 mm3 or 3 mm3 is enough to obtain the above-described effect, although it depends on a kind of the gaseous fuel and dimensions of the internal combustion engine. For example, in a case that the high-pressure gaseous fuel is a hydrogen fuel supplied at a pressure of 60 MPa and a displacement per one cylinder is 2000 cm3, the volume of the injector chamber 43 around 5 cm3 to 10 cm3 is ordinarily enough to prevent the pressure in the nozzle chamber 35 from decreasing.
The injector chamber 43 is continuously supplied with the high-pressure gaseous fuel from the high-pressure gaseous fuel common rail 46 via the high-pressure gas inflow pipe 44 and the gas supply pipe 47. Thus, the pressure in the injector chamber 43 is also prevented from decreasing. As shown in
(Transmission coefficient)=2A1/(A1+A2) (3)
Thus, without further measure, the pressure wave is transmitted to other cylinders to occur pressure interference to fluctuate the fuel injection in the other cylinders. In the first embodiment, an aperture 45 is provided in the gas supply pipe 47 in a close proximity to the high-pressure gaseous fuel common rail 46. A relation between cross-sectional areas of the gas supply pipe 47 and the aperture 45, and a relation between cross-sectional areas of an open port of the high-pressure gaseous fuel common rail 46 and the aperture 45 are determined in accordance with the above-described formulae (2) and (3). That is, a transmission wave passing through the aperture 45 pursuant to the formula (3) is reflected at the open port of the high-pressure gaseous fuel common rail 46, which is an open-end pursuant to the equation (2). The cross-sectional area of the aperture 45 is determined so that the reflection wave reflected at the open port of cancels the transmission wave transmitted through the aperture 45 again, that is, so that a positive and negative phases of the reflection and transmission wave compound with each other. Thus, the pressure wave is prevented from being transmitted through the high-pressure gaseous common rail 46 to other cylinders. Each of the aperture 45 and other apertures has a length that does not occur a phase contrast between the transmission wave transmitted therethrough and the reflection wave reflected thereat. That is, the length is determined so that ((length of aperture)/(sound speed)) can be negligible to keep the phase contrast at 180 degrees between the transmission and reflection waves, which have reversed phases to each other.
As described above, the high-pressure gas passage in the fuel injector 1 has the volume extension portions (the nozzle chamber 35 and the injector chambers 43), and the high-pressure gas passage outside the fuel injector 1 has the aperture 45 at the close proximity to the high-pressure gaseous fuel common rail 46 that has a large volume. This construction serves both a first effect to inject required amount of the high-pressure gaseous fuel without decreasing the injection pressure from the injection hole 37 and a second effect to absorb the pressure wave that occurs at the seat portion 38 in the fuel injection time so as not to affect fuel injections in other cylinders concurrently. Further, the fuel injector 1 has the control chamber 2 so that the high-pressure operating liquid actuates the needle 31. This construction serves both relatively small dimensions of the fuel injector 1 and large driving force to improve injection control performance.
In
A shape of the injection hole 37 that enables high-speed fuel injection is described in the following referring to
It is better that a rounding radius of the rounded portion 37b is larger than the minimum diameter of the injection hole 37, although the rounding radius may be either smaller than the minimum diameter of the injection hole 37 or larger than the minimum diameter to serve the above-described effect. It is desirable that a tapering angle α of the tapered portion 37c is smaller than 20 degrees, more desirably between 5 degrees and 10 degrees to decrease an injection pressure loss.
As shown in
As shown in
In the second embodiment, a high-pressure gas passage 41 is provided by a clearance between an inner face of the injector body 5 and an outer face of the needle 31. The high-pressure gas passage 41 is communicated via a gas inflow pipe 44 to a high-pressure gaseous fuel common rail (not shown). The high-pressure gas passage 41 has a plurality of injector chambers 434, 435 on its way. A first injector chamber 434 is provided in a cylinder wall of the injector body 5 by extending a width of the high-pressure gas passage 41 downstream the gas inflow pipe 44. A second injector chamber 435 is provided by cylindrically recessing an inner circumferential face of the injector body 5 around the needle 31. In the second embodiment, the needle 31 has two guide portions 311a, 311b. A first guide portion 311a slides in the nozzle body 32 and a second guide portion 311b slides in the injector body 5. Outer circumferences of the guide portions 311a, 311b are chambered at their two sides opposite from each other, so as to provide a first feed passage 361a communicated with the second injector chamber 435 and a second feed passage 361b communicated with a first nozzle chamber 351.
In the second embodiment, a nozzle 3 has a plurality of the nozzle chambers 351, 352 therein. The first nozzle chamber 351 has a construction equivalent to that of the nozzle chamber 35 in the first embodiment. A second nozzle chamber 352 is formed at an upper end portion of the nozzle that adjoins the injector body 5. The second nozzle chambers 352 also serve a spring room installing a spring 53 therein. A leading end of the high-pressure gas passage 41 is communicated with the second nozzle chamber 352, so as to feed the high-pressure gaseous fuel via the first feed passage 361a to the first nozzle chamber 351.
The construction of the fuel injector 1 according to the second embodiment requires no operating oil supply path and no control chamber, so that the construction of the fuel injector 1 is simple. Further, a plurality of the injector chambers 434, 435 and a plurality of the nozzle chambers 351, 352 can be formed in the fuel injector 1, so that an effect to keep the gaseous fuel pressure is improved. The fuel injector 1 has an enough volume to supply a maximum fuel injection amount in a large engine. For example, an injection of 2.5 cm3 of hydrogen fuel at a pressure of 60 MPa corresponds to that of 250 mm3 of light oil from a viewpoint of output energy. In this case, 10 cm3 of the volume of the chamber is enough and a pressure drop occurred by the injection is 15 MPa or smaller. Practically, the pressure drop is limited by the gaseous fuel supply from the high-pressure gaseous fuel common rail 46.
The shape of the chambers such as cylindrical one, rectangular hole, and so on and the number of the chambers may be selected in accordance with demands. It is desirable that the chamber is disposed close to the injection holes 37 of the nozzle 3. The chamber, which is disposed so that the sound speed can travel between the injection holes 37 and the chamber in each injection period, is effective for increasing the fuel injection amount.
By the construction of the fuel injector 1 according to the above-described embodiments that injects the high-pressure gaseous fuel directly into the cylinder of the engine, a plurality of the chambers 315, 321, 35 (351, 352), 43 (431, 43a, 43b, 43c, 434, 435) formed in the injector 1 enables its large output power to inject a large amount of the high-pressure gaseous fuel in a short time. The arrangement of the apertures enables a continuous fuel supply from the high-pressure gaseous common rail (or accumulator) upstream the injector 1 by use of the negative pressure wave that occurs at the injection start to induce the gaseous fuel. Further, the construction to flow the high-pressure gaseous fuel passes through the injection hole at the sound speed enables to inject the gaseous fuel having large pressure and large density and to promote a mixture of the gaseous fuel and the air. The high-speed fuel injection and large amount fuel supply from the chambers with little pressure drop realizes the fuel injector 1 that can inject the high-pressure gaseous fuel in a short time. Accordingly, the fuel injector 1 according to the above-described embodiments enables: a large volume injection because of a small density of the gaseous fuel; and highly diffused injection to mix the gaseous fuel with the air in the combustion chamber with reliability. Thus, the fuel injector 1 according to the above-described embodiments enables both a large output power of the engine and a reduction of unburnt fuel emission.
This description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.
Number | Date | Country | Kind |
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2004-302576 | Oct 2004 | JP | national |
2005-222706 | Aug 2005 | JP | national |