|Title of Invention||
THROTTLING HOLE TYPE NOZZLE
|Abstract||The invention is relates to the throttle hole type n~e. 1'he noZlle needle of the tiu-ottle hole nozzle is provided with a. cross hole and overlap on second guide on the needle. The cross hole and overlap lengtjl of the second guide helps in achieving the stepped injection. The second guide is so designed that when the n~le needle opens by the amount of the overlap dimension only a . small quantity of fuel is injected into the combustion chamber, and nlrther when the nO'Z2.le needle is opened to the full stroke the main quantity of fuel is :injected into the Combustion chamber, thereby achieving the two stage injection. The two stage injection produces pilot injection an.d followed thereafter by mmn injection with softer combustion with less noise.|
The invention relates to a fuel injection valve nozzle for direct injection engines, generally to hole type nozzles and more specifically to throttle hole nozzles for achieving stepped injection.
According to known art the nozzle needles lifts sharply and descends shai'ply, the injection rate is high at the start of injection due to sharp lifting action of the nozzle needle and accordingly there is no throttling period. The combustion noise of engine is also high.
OBJECT OF THE INVENTION
ft is the object of the invention to achieve softer combustion with less combustion noise in direct injection engines and more specifically in the idling and part-load ranges
It is the another object of the invention to provide a new and improved tiirottle liole no2sle to achieve stepped injection in direct injection engines.
It is the another object of the invention to provide a new and improved throttle hole nozzle having means for achievmg the stepped injection which shows a desirable soft combustion with least noise.
It is the another object of the invention to provide a new and improved throttle hole nozzle with a second guide to achieve stepped injection in direct injection engines.
ft is the another object of the invention to provide a new and improved throttle hole nozzle with a cross hole and overlap in second guide to achieve stepped injection in direct injection engines.
It is the another object of the invention to provide a nevtr and improved throttle hole nozlle with a cross hole and overlap in second guide to achieve controlled stepped ixijection and thereby maintaining the fuel injection rate.
It is the another object of the iiweution to provide a new and improved throttle hole nozzle to obtain an accurate fuel icgection rate in direct injection engine and thereby reducing the combustion noise in the angles.
It is the another object of the invention to provide a new and improved throttle hole nozzle which is easy and simple to manufacture axiA can be used in the ciirrent type of injectors without any change or modiCLcations.
Ihe fuel injection nozzle according to the invention has a nozzle needle with a second g^ide formed therein and is characterized wherein the second guide on the nozde needle provides the pilot injection and achieves di^yed openu^ of the injection valve.
SUMKAHY OF THE INVENTION
The nozzle needle of the throttle hole nozzle is provided with a cross hole and overlap on second guide on the needle. The cross hole and overlap length of the second guide helps in achieving the stepped injection. The second guide is so designed that when the nozzle needle opens by the amount of the overlap , dimension only a small quantity of fuel is injected Into the combustion chamber, and further when the nozzle needle is opened to the full stroke the main quantily of fuel is injected into the Combustion chamber thereby
achievii^ the two stage im*ection. Hie two stage injection produces pilot injection and folloveed thereafter by main injection with softer combustion with less noise.
pgsciopnoy OF nrvEiiTioir WITH WBrmasxc^ TO PRAwnros
Fig 1: ilhistrates the standard hole type nozzle for direct injection engine.
Fig 2 : illustrates cross sectional view of the throttle hole type nozsde of fiiel injection valve wherein the noz^ stroke is equal to zero. It has a nozzle body with nozzle needle guided axially in the guide bore of the nozzb body. Further the needle has a cross hole and overlap in second guide which extended after the pressure chamber.
Fig 3 : ittastrates cross sectional view of the throttle hole type n
Fig 5 : shows the comparison of graphical representation of lift v/s Flow rate ciirve for both throttle hole type nozzle and standard hole type nozzle.
Pig 6 : illustrates the enlarged detaifed view of portion of the cross hole and overlap dimension of the throttte hole type nozzte wherein the said cross hole and overlap portion on the needle acts as a second guide to achieve stepped ixrjection. The said overlap portion has diameter almost equal to the diameter of the guide bore such that the annular gap in between is narrow.
Reference numerate in drmvvingtt:
1. Nozzle Body.
2. 2"^ guide on needle.
3. 2"^^ guide on body.
5. Nosde stroke.
6. Over lap.
7. Cross hole.
8. Standard hole type no2E2le.
9. Throttle hole type nozzle.
10. Stei>ped injection.
11. Flow rate.
13. Over lap dimension,
DESCRIPTIOir OF THE IirVByTIOir
Generally an injection nozzle comprises an injection orifice, a no^e foody for providing fuel to the iniection orifice, a means for carrying ftiel fi-om pressure chamber to nozsde body (1), a displaceable nozzle needle extending through the nozsle body (1) for opening and closing the injection orifice and a means to load the nozzle needle (4) in the closing direction and maintains it in its closed position counter to the highest fiiel pressure in the nozzle body (1) and a means for exerting upon the nozzle needle (4) a force counteracting the no^s^ie, closing m^eexi^ whereby the nozzle needle is displaced in the opening direction. The displaceable nossde needle extending througli the nozzle body can open ecsxA close the injection orifice and a means which loads the nozzle needle in tlie closing direction exiA permits a displacement of nozszle needle \xx the opening direction when fiiel pressure in nozzle body is greater than a specific value. The overlap between the nozzle needle second guide and the second guide oxx nozzle body (3) results in throttling fiaw. IXiring this period the fiiel passes through the cross hole. This results in pilot injection.
During pilot injection, a small quantity is injected into combustion chamber. During the main injection fastest possible opening and closing of
noissie needle such tiiat sufficient fiael quantity is injected into combustion chamber within a short time.
A fuel injection valve witli throttle hole type nossziB (9) for direct injection engines, wherein the said injection valve comprising ;-
a nozzle body (1) with a guide bore and a nozzle needle axiaUy guided in said guide bore forming a first guide valve for controlling the injection of fuel into the combustion chamber;
said guide bore extended to form a pressure chaxaber;
said second guide valve formed with a second guide on said nozzle needle axially ^ded in a second guide in said nozsde body for a predetermined overlap axial length with a very narrow annual gap therein, between^ and a cross hole communicating between the said pressure chamber at one end and said guide bore at the other end;
wherein for axial m.ovement of said no^le needle until said second guide on nozzle needle overlaps the said second guide on nozzle body (3), the fuel flows from pressure chamber to guide bore through the said cross hole thus achieving pilot injection.
wherein for further axial movement of said nozzle needle beyond which the said second guide on nozizle needle is not overlapping the second guide on tJie nozzle body (1) the fuel flows from pressure chamber into guide bore, thus achieving main injection.
Hie principle of valve opening is when the fuel pressure acts upon the nozzle needle with an opening force that acts counter to closing force acting on nozzle needle in the direction of noT^le tip^ then nozzle needle is deflected in the
direction of pressure chamber aiid as a result the injection vaive opens and fuel is injected into the combustion chamber.
During the waive opening of the throttle nozzle vab/B as per the invention having two guide valves first guide valve opens but second guide valve remains closed as long as moveaaaent of nozzle needle does not exceed the predetemiined overlap stroke. The volume of the pressure chamber decreases upon first guide valve opening but the second giiide valve remaining closed, and thereby the fuel is compressed thereby. Thereafter when the movement of the nozzle needle exceeds the overlap stroke the second guide valve also opens and thus compressed ftiel floivs out of the pressure chamber and the delay in first valve opening thus ceases.
Thus the injector has tlie nozzle needle adapted with the said second guide valve and disposed on the nozzle needle (4), and which opens with a delay after the valve opening up to a predetermined overlap stroke. As such in tile pre injection or pilot injection, only a smaller and defined voiutne of fuel via second guide valve is dispersed into the combustion chamber and thereby opening of injection valve is delayed.
The no^e needle and the second guide are embodied as a single unit comx)rising a single body in the present invention.
The delay of valve opening in the present invention is calculated by means of suitable overlap lengtli measurement of the assembly-
WE CLAIM :-
1. A fael injection valve with throttle hole type nozzle (9) for diiect injection engines J wherein the said injection valve comprising :-
a nozzle body (1) with a guide bore and a nozzle needle (4) axially guided in said guide bore, the said nozzle needle forming a first guide "vais^e in the form of encompassing edge for controlling the injection of fuel into the combustion chamber,
said guide bore extended to form a pressure chamber; a second guide formed on said ntxszie needle between said pressure chamber and said guide bore, said second guide comprising a overlap portion of second guide diameter and another portion of needle guide diameter, and a cross hole (7) on the needle (4) communicating between said pressure chaanber at one end and said guide bore at the other end, said overlap portion of said second guide having a diam.eter almost equal to diameter of said guide bore such that annular gap inbetween is very narrow to create a sealing effect and thereby to form a second guide valve»
said second guide valve connecting the said pressure chamber with said second guide bore relating to degree of movement of said no^le needle
wherein for axial movement of said nozzle needle less tlian the predetermined overlap portion, the fuel flows from pressure chamber to guide bore through the said cross hole thus achieving pilot injection*
wherein for further axial movement of said nozzle needle beyond predetermined overlap portion, tlie fuel flows from pressure chamljer into guide bore, thus achieving main injection.
2. A fuel injection valve with throttle hole type nozzle (9) for direct injection
engines as claimed in claim 1, wherein the nozzle needle (4) and second guide
are embodied as a single body,
3. A fuel injection valve with throttle hole type noszle (9) for direct injection engines as claimed in claim 1, wherein the said overlap portion of said second guide has a diameter greater than the given needle diameter of the nozde needle (4) and in almost equal to the diameter of the guide bore.
4. A fuel injection valve with throttle hole type nozzle (9) for direct injection engines as claimed ia claim 1, wherein said overlap portion has a predetermined lengtli.
5. A fuel injection valve with throttle hole type nozzle (9) for direct injection
engines as claimed in claim 1, nvherein said second guide is formed witJh a
cross hole (7) and an overlap portion.
|Indian Patent Application Number||632/CHE/2003|
|PG Journal Number||38/2007|
|Date of Filing||04-Aug-2003|
|Name of Patentee||M/S. ROBERT BOSCH GMBH|
|Applicant Address||STUTTGART, FEUERBACH|
|PCT International Classification Number||F 02 M 55/00|
|PCT International Application Number||N/A|
|PCT International Filing date|