Source: http://www.google.com/patents/US6302080?dq=5,915,131
Timestamp: 2015-07-30 02:54:27
Document Index: 530020587

Matched Legal Cases: ['art 50', 'art 50', 'art 50', 'art 50', 'art 50', 'art 50', 'art 56', 'art 50', 'art 50', 'art 80', 'art 80']

Patent US6302080 - Fuel injection system having pre-injection and main injection - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inAdvanced Patent SearchPatentsThe angle of fuel spray at the time of pre-injection is set to a wider angle of spray and the angle of fuel spray at the time of main injection is set to a narrower angle of spray. The pre-injection timing is set so that when fuel spray after the pre-injection is diffused in a cylinder and stratified,...http://www.google.com/patents/US6302080?utm_source=gb-gplus-sharePatent US6302080 - Fuel injection system having pre-injection and main injectionAdvanced Patent SearchPublication numberUS6302080 B1Publication typeGrantApplication numberUS 09/352,197Publication dateOct 16, 2001Filing dateJul 13, 1999Priority dateJul 31, 1998Fee statusPaidAlso published asUS6644269, US20010039935Publication number09352197, 352197, US 6302080 B1, US 6302080B1, US-B1-6302080, US6302080 B1, US6302080B1InventorsMasaaki Kato, Toshiyuki Yoda, Kenji DateOriginal AssigneeDenso CorporationExport CitationBiBTeX, EndNote, RefManPatent Citations (9), Non-Patent Citations (2), Referenced by (21), Classifications (34), Legal Events (5) External Links: USPTO, USPTO Assignment, EspacenetFuel injection system having pre-injection and main injection
US 6302080 B1Abstract
fuel injector for directly injecting fuel into a cylinder of an internal combustion engine; and control means for executing an injection of the fuel from the fuel injector by a pre-injection and a main injection per cycle of the internal combustion engine, wherein the control means controls the fuel injector so that the fuel injected by the pre-injection is formed into a stratified spray of uniform mixture concentration in a predetermined zone in the cylinder at an ignition timing after the pre-injection, and the fuel injected by the main injection passes through the stratified spray zone formed by the pre-injection and burns with an un-used air remaining in a zone in the cylinder other than the predetermined zone; and wherein the pre-injection and the main-injection are separated by a non-injection interval. 2. A fuel injection system according to claim 1, wherein the fuel injector is constructed so that the angle of fuel spray formed by the fuel injection can be adjusted, and
the control means controls quantity and timing of fuel injection of the fuel injector so that the angle of fuel spray is wider at the time of pre-injection and the angle of fuel spray is narrower at the time of main injection. 3. A fuel injection system according to claim 1, wherein the control means controls fuel injection quantity and fuel injection timing at the time of the pre-injection in accordance with operating conditions of the internal combustion engine so that the fuel spray stratified by the pre-injection is on a lean side in an inflammable mixture limit and cool-flame burned.
a nozzle body having a nozzle hole for injecting fuel; a needle which is slidably provided in the axial direction in the nozzle body and opens and closes the nozzle hole; means for lifting the needle in stages according to a balance between a fuel pressure which biases the needle in a valve opening direction and a biasing force of a plurality of biasing means which urge the needle in a valve closing direction; and a fuel passage which is provided between the needle and the nozzle body and by which a rate of injection and spray conditions of a fuel to be injected are changed according to a lift of the needle. 7. A fuel injection system according to claim 6, further comprising:
first biasing means for biasing the needle in a valve closing direction and second biasing means for biasing the needle in a valve closing direction when the lift of the needle is larger than a first lift. 8. A fuel injection system according to claim 1, wherein the fuel injector includes:
a nozzle body having a valve seat member upstream of a nozzle hole; a needle which is supported by the nozzle body slidably and reciprocally and has a contact part which can seat on the valve seat member, for interrupting and permitting the flow of a fuel by making the contact part unseated and seated on the valve seat member; a first swirl flow generating chamber formed in the nozzle body, for generating a swirl flow of a fuel; and a first swirl flow generating part which is provided around the needle and has an outer wall in which a first fuel inlet passage communicated with the first swirl flow generating chamber is formed, wherein the outer surface of the first swirl flow generating part in which the first fuel inlet passage is formed faces the inner surface of the nozzle body in which the valve seat member is formed. 9. A fuel injection system according to claim 8, wherein the inside diameter of the first swirl flow generating chamber in the nozzle body is smaller than the outside diameter of the first swirl flow generating part in which the first fuel inlet passage is formed.
a second swirl flow generating chamber which is formed in the nozzle body upstream of the first swirl flow generating chamber, for generating a swirl flow of a fuel; and a second swirl flow generating part which is provided on the outer surface of the needle upstream of the first swirl flow generating part and has an outer wall or an inner wall in which a second fuel inlet passage communicated with the second swirl flow generating chamber is formed. 11. A fuel injection system according to claim 1, further comprising a fuel accumulation chamber for accumulating fuel therein, said fuel accumulation chamber being connected to said fuel injector.
Specifically, the injector 3 is comprised of a nozzle body 33 in which a needle 31 is housed movably and an injector body 35 having therein a driving system for opening and closing the injector 3 by displacing the needle 31 by using the high pressure fuel in the common rail 5. In the nozzle body 33, a fuel chamber 33 a for temporarily storing the high pressure fuel supplied from the common rail 5, fuel path 33 c for leading the high pressure fuel in the fuel chamber 33 a to a nozzle hole 33 b, and a needle insertion hole 33 d into which the needle 31 can be inserted from the side opposite to the fuel path 33 c of the fuel chamber 33 a and which slidably supports the inserted needle 31 coaxially with the fuel path 33 c. The tip on the side of the fuel chamber 33 a of the needle 31 is formed in a taper shape so as to interrupt a flow of the fuel from the fuel chamber 33 a into the fuel path 33 c (and to the nozzle hole 33 b) by being in contact with the opening on the fuel chamber 33 a side of the fuel path 33 c. From the center of the tip, a guide part 50 for swirling the high pressure fuel supplied through the fuel path 33 c to the nozzle hole 33 b is projectingly provided.
A rod 39 for connecting the needle 31 and the piston 37 is provided between the needle 31 and the piston 37, which extends in the center of the first hole 35 a. On the inner wall of the first hole 35 a, a hollow regulation plate 35 c is provided. The regulation plate 35 c comes into contact with the rear end of the needle 31 when the needle 31 moves backward, that is, when the needle 31 frees the fuel path 33 c extending from the fuel chamber 33 a to the nozzle hole 33 b to allow the fuel to be injected from the nozzle hole 33 b), thereby checking the backward movement of the needle 31 and regulating the maximum opening area of the path of the high pressure fuel injected from the nozzle hole 33 b. Further, on the second hole 35 b side rearward of the regulation plate 35 c of the first hole 35 a, a coil-shaped first spring 41 a whose one end is in contact with a stepped part extending from the first hole 35 a to the second hole 35 b is provided.
The rod 39 has a flange 39 a which is in contact with the other end of the first spring 41 a in a some midpoint of the backward movement of the needle 31 until the rear end of the needle 31 comes into contact with the regulation plate 35 c,and temporarily checks the backward movement of the needle 31 by the biasing force of the first spring 41 a. The side opposite to the first hole 35 a of the second hole 35 b is communicated with a control chamber 46 in which the fuel pressure is controlled by a three-position valve 43 and a one-way orifice 45. The end face on the opposite side of the rod 39 of the piston 37 receives the force of biasing the needle 31 toward the fuel path 33 c from a coil-shaped second spring 41 b provided in the control chamber 46. The second spring 41 b has a diameter smaller than that of the first spring 41 a and generates a biasing force smaller than that of the first spring 41 a. The three-position valve 43 is provided in the fuel path extending from the common rail 5 to fuel tank 47. In the normal times when an electric current is not supplied to a solenoid 43 a, a valve body 43 b closes the port on the fuel tank 47 side to lead the high pressure fuel from the common rail 5 to the control chamber 46 via the one-way orifice 45. When the current is supplied to the solenoid 43 a, the valve body 43 b is moved to the port on the common rail 5 side to close the port and the one-way orifice 45 and the fuel tank 47 are communicated with each other, thereby decreasing the fuel pressure in the control chamber 46.
The one-way orifice 45 comprises: fuel paths 45 a and 45 b of two channels each communicating the port on the one-way orifice 45 side of the three-position valve 43 and the control chamber 46; a nonreturn valve 48 which is provided in one, 45 a, of the fuel paths, permits the fuel flowing from the three-position valve 43 into the second hole 35 b side, and checks the flow of the fuel in the opposite direction; and a throttle 49 which is provided for the other fuel path 45 b and restricts the quantity of fuel flowing through the fuel path 45 b. As shown in FIG. 2A, the guide part 50 is constructed slidably in the fuel path 33 c. In the center of the side wall of the guide part 50, an oblique groove 52 to swirl the high pressure fuel flowing through the fuel path 33 c to the nozzle hole 33 b is formed.
In a fuel injector shown as a comparative example, as shown in FIG. 2B, a part from the center of the guide part 50 in which the oblique groove 52 is formed to the tip which comes into contact with the inner wall of the nozzle hole 33 b is formed to have a taper face 54 whose diameter gradually decreases toward the tip, thereby creating an almost constant swirl flow irrespective of a needle lift amount. In the injector 3 of the embodiment, however, as shown in FIG. 2A, the part from the center of the guide part 50, in which the oblique groove 52 is formed, to the tip which comes into contact with the inner wall of the nozzle hole 33 b is formed in a cylindrical shape along the center axis of the guide part 50, thereby forming a swirl chamber 58 defined by the outer wall of a cylindrical part 56 and the inner wall of the fuel path 33 c. Consequently, in the injector 3 of the embodiment, the shape of the swirl chamber 58 (specifically, height (h) along the axial direction) changes according to the needle lift amount. When the height (h) of the swirl chamber 58 changes, the fuel flow from the oblique groove 52, having a velocity vector in the oblique direction changes the ratio between an axial velocity component of the guide part 50 and a circumferential velocity component of the swirl chamber 58 of the velocity vector. The change is caused by a variation in a radial rectification in fuel outlet part through which the fuel flows from the oblique groove 52 to the nozzle hole 33 b side and a variation in the fuel inertia according to a swirl chamber volume. The variations occur at a height (ho) of the swirl chamber 58. The change in the velocity direction component ratio appears as a change in the angle of spray of the fuel injected from the nozzle hole 33 b. In the injector 3 of the embodiment constructed as described above, when no current, that is no driving pulse DP, is supplied to the solenoid 43 a of the three-position valve 43, the high pressure fuel in the common rail 5 flows via the three-position valve 3 and the one-way orifice 45 into the control chamber 46. As a result, the piston 47, rod 39 and needle 31 are energized to the nozzle hole 33 b side by the high pressure fuel flowed in the control chamber 46 and the taper face of the needle 31 comes into contact with the opening on the fuel chamber 33 a side of the fuel path 33 c to thereby close the fuel path 33 c, so that the injector 3 enters fuel stop state.
At the time of the movement, since the biasing force of the second spring 41 b is applied only to the piston 37 in the beginning, the elements quickly move backward. When the movement amount (needle lift amount) L reaches a predetermined amount (L1 shown in FIG. 1) and the flange 39 a comes into contact with the first spring 41, the movement of the elements is temporarily stopped by the biasing force of the first spring 41 a. At this time, the height (h) of the swirl chamber 58 becomes a height (ho+L1) obtained by adding the needle lift amount L1 to the height ho in the initial state where the nozzle hole 33 b is closed. In this state, however, the volume of the swirl chamber 58 is small and the fuel inertia is small, so that the circumferential velocity component of the fuel flowing from the oblique groove 52 of the guide part 50 to the nozzle hole 33 b side is strongly maintained and the angle of spray of the fuel injected from the nozzle hole 33 b becomes a wider angle al of spray (FIG. 3).
That is, in the injector 70, the needle 74 opens or closes the opening part extending from a fuel chamber 76 a on an injector body 76 side formed around the needle 74 to fuel path 78 a on a nozzle body 78 side, thereby enabling the flow of the high pressure fuel supplied from a common rail (not shown) via the fuel chamber 76 a to the fuel path 78 a on the nozzle body side 78 to be adjusted. The needle 74 is mounted in the opening part of the fuel path 78 a by the biasing force of a coil-shaped spring 79 built in the injector body 76 to check the flow of the fuel to the fuel path 78 a. When the current is supplied to the solenoid 72 provided thereabout, the needle 74 is moved in the direction of freeing the opening part of the fuel path 78 a by the magnetic force generated by the solenoid 72 in accordance with the amount of the supply of the current. A rod 74 a projected from the needle 74 is housed in the fuel path 78 a of the nozzle body 78 and a guide part 80 constructed in a manner similar to the first embodiment is provided at the tip of the rod 74 a. According to the injector 70 shown in FIG. 13, therefore, as shown in FIG. 14, the needle lift amount (and moreover the height of a swirl chamber 82 formed by the guide part 80) is adjusted by a driving pulse current supplied to the solenoid 72 and the angle α of spray of the fuel injected from a nozzle hole 78 b of the nozzle body 78 can be accordingly changed.
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