DE3213529A1 - Fuel injection nozzle - Google Patents

Description

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1 L 66 P

Applicant ; LUCAS INDUSTRIES LIMITED,

Great King Street, Birmingham, B 19 2XF, England

description of

Invention fuel injector

description

The invention relates to a fuel injector for delivery from fuel to internal combustion engines with internal combustion and pressure ignition, a nozzle housing enclosing a bore, at one of which At the end there is an outlet and near this outlet there is a valve seat with which a valve member which is adjustable in the bore cooperates to create the outlet controlling fuel from an inlet through the outlet; resilient means adjust the valve member in the direction of the valve seat, while on a first surface of the valve member fuel under pressure to act can be brought to lift this against the action of the spring from the seat.

The injection nozzles of internal combustion engines is fueled by means of a Fuel pump supplied. The fuel is under high pressure and the nozzles are connected to the outlet or the delivery side of the pump, mostly via high pressure lines. Will the supply of fuel to a If the nozzle is interrupted, the pressure in the fuel ducts of the pump drops,

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of the lines and the nozzle quickly drop to a residual value. The purpose of this pressure drop is to ensure that the valve member is quickly brought to seat on the valve seat to prevent after-dribbling of fuel through the To prevent outlet of the nozzle. The adjustment of the valve member opposite the valve seat and the cessation of fuel flow create a pressure wave in the fuel column and this pressure wave circulates back to the pump to be reflected back to the nozzle again. Thereby the pressure increase be so high at the nozzle that the valve member is lifted from its seat in order to allow an undesired fuel to escape again. This Phenomenon is known as a second or post-injection and, like after-dripping, is undesirable.

The object of the present invention is to develop a generic Fuel injection nozzle in a simple and expedient manner so that the second or Post-injection is reliably avoided, or the risk of such a second or post-injection is reduced to a minimum.

According to the essential feature of the invention, this object is thereby achieved solved that in a generic fuel injection nozzle, the valve member is divided into two parts in the bore of the nozzle housing relative to each other are movable, the nozzle having means by which it is allowed the fuel under pressure from the inlet towards opposite one another Areas between the two parts of the valve member to act at least when the valve member is in the closed position, further means are provided to the extent of movement of both valve member parts apart to limit and finally being the opposing faces

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of the two valve member parts on which the fuel pressure acts to the valve member parts to cause them to move away from each other, equal in size but larger than that are the former valve member area.

Three exemplary embodiments of the invention are shown below with reference to the drawing in which the three exemplary embodiments are shown as central longitudinal sections are.

According to FIG. 1 of the drawing, the nozzle includes in its entirety 10 designated nozzle housing, the cylindrical outer contour of which is stepped, the housing 10 being assigned to a nozzle holder with the step.

The housing 10 encloses a longitudinal bore 11 which opens into an outlet 12 and which forms a seat 13 in the vicinity of the outlet 12. Near the seat 13 the longitudinal bore 11 is widened to form a first chamber 14, which by means of a flow channel 15 of the nozzle housing 10 with a fuel inlet is connected, which is arranged in the nozzle holder and is connected in the operating state to the outlet of a fuel injection pump.

Within the longitudinal bore 11 there is a valve member, which in its entirety is denoted by 16 and consists of two parts 17, 18. The part 18 is intended to interact with the valve seat 13 and is designed accordingly. If the part .18 is seated on the valve seat 13, fuel will escape from the first chamber 14 through the fuel outlet 12 prevented. The part has an area within the chamber 14 upon which fuel under pressure is applied can act in order to lift the valve member from the valve seat 13 can.

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During operation of the part 17 there is a spring abutment on which

a spring is supported at one end, which according to the task the valve member with Bias on the valve seat 13 presses. In the closed position of the valve, the part 18 of the valve member sits on the valve seat 13 and both parts 16 and touch one another, but include a second chamber 19 which is in communication with the flow channel 15.

During operation, fuel passes through the flow channel under pressure in the chambers 14 and 19 and acts on those in the chamber 19 opposite one another Surfaces of parts 17 and 18 and onto the surface of the valve body in chamber 14. The surfaces of parts 17 and 17 exposed to fuel pressure 18 in the chamber 19 are equal to each other, but greater than that of the fuel pressure exposed surface of the valve member in the chamber 14. The fuel acting under pressure on the surfaces of the part 17 causes the parts 17 and to separate from each other and the extent of the axial movement required for this the parts are limited by a mechanical connection, denoted by 20 is. This mechanical connection first enables the part 17 to move away from the valve seat 13 against the action of the spring. Has this allowed Movement reaches its end, the effect of the fuel pressure in the chamber 14 on the surface of the part 18 lying therein, that both parts Remove 17 and 18 together from valve seat 13. As a result, fuel passes through outlet 12 into the associated internal combustion engine. Is the outflow of Fuel ends and the fuel pressure falls in the flow channel 15, then both parts 17, 18 of the valve member approach the valve seat 13 again, the part 18 finally comes to rest again on the valve seat 13 and an outflow of fuel through the outlet 12 is again prevented. It can

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be that both parts 17 and 18 are together, i.e. touching each other on the valve seat move towards, and this can then be done and ensured, if a narrowed opening 21 is provided in the part of the flow channel 15 leading to the first chamber 14.

After closing the valve by placing the valve member on the A pressure wave will form in the flow channel 15 before the valve seat however, the part 18 of the valve member can move thereby, in order to enable a second injection, the part 17 must move relative to the permissible amount have partly moved 18. This movement of the part 17 absorbs the pressure wave, so that a second injection or post-injection of fuel is prevented. Once the pressure wave has come to an end, part 17 moves back, to get in contact with part 18 again.

In the arrangement of FIG. 2, the mechanical connection 20 is through a H ydraulic connection replaced. Referring to FIG. 2, they correspond to Parts 22, 23 to parts 17, 18 of the above-described arrangement according to Fig.l and they form a piston and cylinder unit, which in their entirety with is designated. In this case, fuel can be introduced into the cylinder provided in part 22 under pressure. The introduction of the fuel into the Cylinder takes place through an opening 25 which initially leads to the flow channel is open, which, however, is brought out of connection with the flow channel 15 when the part 22 has moved a predetermined amount. While the opening 25 is in communication with the flow channel 15, the Fuel pressure in flow channel 15 separates parts 22 and 23 of the

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Valve member from each other, as it is also in the embodiment according to FIG. the case is. If, on the other hand, the opening 25 is covered, no further takes place Relative movement between these two parts and both parts move under the influence of the fuel pressure acting on part 23 together. This allows fuel to flow out through outlet 12 and during the rest of the time Movement of the valve member, a flow channel 26, which is in communication with the cylinder in part 22, is brought into connection with a drainage, which in practice is a chamber in the nozzle holder. The pressure in the cylinder therefore drops and allows the two parts of the valve member to move for as long until they have contact with each other. When the flow of fuel ends, the two parts of the valve member move together into the position shown in FIG. 2 position shown. If a pressure wave occurs in the flow channel 15, the part 22 of the valve member is raised in order to absorb the pressure wave, without a second injection taking place. It should be noted that the areas of the opposing surfaces of the two Portions of the valve member initially exposed to inlet pressure are substantially equal to and larger than the area of the area of the valve member within the chamber 14 are. If the hydraulic connection is created, the areas of the opposing surfaces of the parts of the valve member, which are still exposed to the inlet pressure, that is, the area of the annular step of the part 23 and the area of the annular end face of the part 22, smaller than the surface area within the chamber 14. The two parts therefore move like a single part against the effect the feather.

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Should it be necessary, the flow channel 26 can be dispensed with. ?

ϊ> If in this case both parts of the valve member are under the effect f

the rising pressure separately from each other, they remain from each \

I-other disconnected until the pressure at the fuel inlet towards the end of the fuel supply?

falls off. They then move together against the seat until the opening 35 is I

is reopened. The two parts continue to move against the seat, f

while the part 22 moves against the part 23. ί

In the example of Fig. 3 is a more practical solution to that Formation of the valve according to FIG. 2 is shown. However, it operates in a manner similar to the operation of the solution of Figure 2 when there the flow channel 26 is omitted.

According to FIG. 3, the parts 27, 28 again correspond to the parts 22, 23 of FIG. 2 and they also again form a piston-cylinder unit, the part 27 forming the cylinder 29 and the part 28 forming the piston 30. The cylinder 29 defines a Pair of openings 31, which are in constant communication with the fuel inlet channel 15; stand. In the closed position of the nozzle, the part 27 comes under the action i

the nozzle spring to interact with the part 28 and at the point in time I.

in which this happens, there is a step 33 of the piston 30 in such an I.

Position to the cylinder openings that the annular gap 32 between the cylinder 29 f

and the reduced cross-section of the piston, which is through the step 33 I.

is formed, communicates with the fuel inlet duct, so that the \

End faces of both parts of the valve member the pressure in the fuel inlet channel 15 f

are exposed. The areas of these surfaces are larger than the area of the I.

first surface of the part 28 in the region of the valve seat 13 due to the fact ϊ

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that in the closed position of the nozzle part of the first end faces through the Valve seat is covered against the fuel pressure in the fuel inlet duct.

If the pressure in the fuel inlet channel increases, then, as in the previous examples, part 27 is raised against the action of the spring and the relative movement of the parts against one another continues until the piston shuts off area 32 from the pressure in the fuel inlet channel and a hydraulic connection is created . Both parts then move together against the action of the spring in order to enable the fuel in this example to flow through the outlet openings 34. If the pressure drops, the two move ^: parts against the seat and, when the part 28 comes into contact with the seat, the part 27 continues its movement until it hits the part 28. As in the previous examples, the initial movement of part 27 relative to part 28 serves to absorb the pressure wave or waves that occur after the nozzle is closed. It should be noted that the lifting of the parts together away from the seat is limited to ensure that the hydraulic connection in area 32 is not broken when the parts approach their maximum raised position.

In summary, the invention can be presented again as follows. * The invention relates to a fuel injection nozzle which opens inward and the valve member is divided into two parts 17, 18, which in the axial direction are movable relative to each other. The extent of the relative movements between the two parts is limited by appropriate means 19. On each other * opposite surfaces of the two parts of the valve member can fuel -. act with the pressure prevailing in the fuel inlet 15. Who oppose each other

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overlying surfaces are larger than the fueled surface of the a valve member part 18 which cooperates with the valve seat 13. During the initial delivery of fuel, both valve member parts move relatively to each other while they are thereafter moved as if integrally to allow fuel to pass through the outlet 12. When the flow of fuel ends, come the valve member on the valve seat to rest and then shock waves occurring in the fuel are absorbed by relative movements between the two valve member parts.

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Claims (8)

L 66 P 274 Applicant : LUCAS INDUSTRIES LIMITED, Great King Street, Birmingham, B 19 2XF, England description of Invention fuel injector Claims il./ Fuel injector for supplying fuel to internal combustion engines with internal combustion and pressure ignition, a housing of the nozzle enclosing a bore, one end of which is an outlet and the near this outlet forms a valve seat with which an adjustable in the bore Valve member cooperates to control the outlet of the fuel coming from an inlet, with a spring means on the one hand on the valve member acts to keep the valve member on the valve seat and on the other hand on a surface of the valve member below the fuel coming from the inlet Pressure acts in order to be able to lift the valve member from the valve seat against the action of the spring means, characterized in that the valve member (16; 24; 27.28) is divided into two parts (17.18; 22.23; 27.28), the are movable relative to one another in the bore (11), means being provided are, which allow the fuel from the inlet under pressure on opposite surfaces between the two parts at least to act when the valve member is in the closed position, and wherein further means (20, 24, 30) for limiting the extent of the response both parts are provided apart from one another, and finally the opposing surfaces being equal to and larger than the first-mentioned surface of the valve member are. April 9, 1982 - 2 - 2. Fuel injection nozzle according to claim 1, characterized in that the | Means to limit the extent of the movements of both parts (17, 18) % include a «Vont.il () lin <1tt» (] C>) nuaoinniuior oine mochanioche connection (20). § 3. Fuel injection nozzle according to claim 2, characterized in that between * the fuel inlet (15) and a chamber (14) forming an enlarged * Part of the housing bore (11) a throttle point (21) is provided, wherein | the former valve member area is located within this chamber. | 4. Fuel injection nozzle according to claim 1, characterized in that the Means for limiting the extent of the movement of both parts (22,23; 27,28) of the valve member (24; 27,28) apart, a hydraulic connection include that after a limited relative movement of the two parts of the valve member under the action of the fuel pressure in the fuel inlet (15) comes into effect. 5. Fuel injection nozzle according to claim 4, characterized in that the opposing surfaces are parts of a piston-cylinder unit (24), in which an opening (25) is arranged in the cylinder wall, which in the open position of the valve member (22,23) with an opening in the nozzle housing (10) is in free connection, which in turn with the fuel in-InO (Γ>) vorlnindon int, with both openings separated from each other are when both parts of the valve member approach each other to the hydraulic To create connection. S. L 6 6 P 274 April 9, 1982 - 3 - 6. Fuel injection nozzle according to claim 5, characterized by a flow channel (26) in one of the two parts (22,23) of the valve member with the cylinder is in communication and opens freely into a drainage after the two parts of the valve member have touched each other and around a predetermined amount against the action of the spring together have moved. 7. Fuel injection nozzle according to claim 6, characterized in that the Cylinder of the piston-cylinder unit (24) and the flow channel (26) in which the two parts (22,23) of the valve member (24) are arranged, which is the Valve seat (13) is further away. 8. Fuel injection nozzle according to claim 4, characterized in that the one of the opposing surfaces, which is assigned to the part (28) of the valve member (27, 28) which cooperates with the valve seat (13), one Piston (30) forms slidingly into a cylinder (29) which di <; forms the other of the two opposing surfaces, the cylinder wall having an opening (31) which is continuously connected to the fuel inlet (15) is connected, the piston further having a step between the cylinder wall and an annular space (32) which is in the closed position of the valve member with the opening in the cylinder wall in communication, while this opening is closed by the piston after the two parts of the valve member have covered a predetermined distance relative to one another have to establish a hydraulic connection between them in the annulus. L 66 P 274
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