DE3540780C2 - - Google Patents

Description

The invention relates to a fuel injector for Injection internal combustion engines according to the preamble of Claim 1.

It is known to use direct injection engines Two-fuel operation to reduce the ignition fuel share after its injection into the combustion chamber second fuel, called main fuel, in the Inject combustion chamber. It can be z. B. at the ignition fuel for diesel fuel and the Main fuel is alcohol fuel its combustion more environmentally friendly exhaust gases than with the combustion of diesel fuel. However the alcohol fuels have a relatively high ignition temperature, which is why the inflammation of the alcohol fuel by that of diesel fuel must be directed.  

For the injection of ignition and main fuel in direct injection engines are different types sprayers known. Doing so will burn of the ignitable ignition fuel the temperature in the Combustion chamber above the ignition temperature of the ignition unwilling main fuel raised.

From DE-OS 32 43 176, of which the preamble of Claim 1 is a fuel known injection nozzle, the first one from the pressure of the Ignition fuel controlled valve needle for ignition fuel and a second also from the pressure of the Ignition fuel controlled valve needle for the main has fuel. Both valve needles protrude Spray holes in connection with the combustion chamber. Everyone Valve needle is assigned to a control chamber that with the supply line for ignition fuel is connected. In addition, the second valve needle is another Collection chamber assigned to the supply line for Main fuel is connected. The timing The two valve needles are controlled in this way the pressure of the ignition fuel that first the first Valve needle opens and ignition fuel in the combustion chamber is injected; if the pressure of the Ignition fuel, the second valve needle is opened and main fuel from the plenum into the combustor injected space. The main force injection Accordingly, the substance becomes that of the ignition fuel accompanied. Towards the end of the injection phase it closes first the second and a short time later the first Valve needle. With this injector throughout the main fuel injection process ignition fuel also injected into the combustion chamber, whereby the proportion of ignition fuel is relatively high.  

In addition, an injection device according to DE-OS 29 24 128 known, which is also a first valve needle for ignition fuel and a second valve needle for Main fuel has. The control of the two Valve needles are made by the pressure of the main fuel. This is done in a pilot injection ignition fuel at the beginning of the cylinder Injection phase via a differential piston, which from Pressure of the main fuel is moved from the front injection cylinder out over the control chamber of the first valve needle injected into the combustion chamber. The second valve needle is then passed through the further increasing pressure of the main fuel ge opens, and it gets main fuel into the combustion chamber sprayed. So with this injector the ignition fuel only in front of the head fuel injected. The amount of ignition fuel is constant because it is determined by the size of the Pre-injection cylinder measured fuel quantity be is true, however, in terms of performance depending on different need for ignition fuel is disadvantageous.

The invention has for its object a Injection device for injection fuel machines create, in which the proportion of ignition fuel per Injection cycle in relation to the main fuel percentage is low and also adapts depending on the operation.

This object is achieved by a force fabric injection nozzle with the in the hallmark of the patent claims 1 listed features solved.  

The injection device according to the invention has the two valve needles, which are the injection of the control both fuels, an interruption valve on. It is one of the main fuel controllable valve that controls the fuel path of the Zünd shut off fuel. If the break valve is not it is in its open position, in which it is biased by a biasing force and in which it is not the fluid path of the ignition fuel interrupts. Control by the main fuel takes place in such a way that when the second valve needle is open the pressure of the head injected into the combustion chamber fuel to control the break valve, the then takes its closed position, is used. The interrupter valve in turn interrupts here through the ignition fuel injection essentially for the time when the main fuel in the Combustion chamber is injected.

Shortly after the start of the main fuel injection the cut-off valve interrupts the ignition fuel feed inside the injector. This interruption happens with a certain time delay, so that for a short time both ignition and Main fuel to be injected into the combustion chamber. In this transition phase, the one already inflamed conducts Ignition fuel the combustion of the be in the combustion chamber sensitive and until the end of the injection cycle in the Combustion chamber injected main fuel. Against At the end of the injection phase, the pressure in the ignition drops fuel line again, so that the second Valve needle closes. The break valve takes then with a certain time delay its initial state due to the preload  again. During this delay time, the Pressure in the ignition fuel line is already below the Opening pressure of the first valve needle dropped so that towards the end of the injection phase, no more ignition fuel gets into the combustion chamber.

In the injection device according to the invention Ignition fuel only at the beginning of an injection cycle and essentially before the main fuel in the Injected combustion chamber, being an ignition aid for the Main fuel is used. The amount of injected Ignition fuel depends on it. a. from the speed speed of pressure build-up of the ignition fuel at one Injection process from. A change in operations conditions of the engine with regard to the speed on the delivery rate of the injection pump for the Ignition fuel and also has a time changing pressure build-up of the ignition fuel on spraying result. With the so changing Pressure build-up also changes the time span within which addresses the second valve needle, and thus the Amount of ignition fuel until the interruption of the Ignition fuel injection into the combustion chamber has been injected. Thus the amount of ignition fuel depending on the operating speed adjusted and it can over the entire speed and Load range of the engine a large amount of Ignition fuel saved and by main fuel to be replaced, safely igniting the head fuel is always guaranteed.

Advantageous embodiments of the invention can be take from the subclaims.  

This is an advantageous development of the invention given by the features according to claim 2. Since the Valve needle through the ignition fuel injection Blocking the narrow spray hole for the ignition fuel interrupts, the needle can act as a needle valve formed break valve and this in total their dimensions are made small so that the mass to be moved is low.

Another advantageous embodiment of the invention is characterized by the features according to claim 3. If during the main fuel injection the sub is activated, the valve presses needle against their valve seat surface, causing the two Sections of the spray hole for the ignition fuel be separated from each other by the valve needle. Through this type of interaction of the interrupter valve and the spray hole is achieved that Dead volume within the spray hole as low as is possible.

Another advantageous embodiment of the invention arises with the features according to claim 4. Here the interrupter valve speaks only when the valve is open second valve needle, the pressure of the by the Spray hole in the combustion chamber main injected fuel through the pressure hole on the control surface of the interruption valve acts, whereby this the Ignition fuel injection stops. The main force The material is fed at constant pressure. The Activation of the interrupter valve is done indirectly by the second valve needle, over which the main one fuel injection takes place, controlled. Fall with it Control and main fuel injection together.  

In the injection nozzle according to the invention for Main fuel injection time the injection interrupted by ignition fuel. The ignition fuel is therefore only used to ignite the main fuel Start the injection phase in the combustion chamber sprayed. So that the ignition fuel portion be reduced. The per injection phase in the combustion The amount of ignition fuel injected is not con constant and depends on the engine to deliver Power.

Below is a reference to the figures Embodiment of the invention explained in more detail.

Show it:

Fig. 1 shows a longitudinal section through the injection nozzle and

Fig. 2 is a plan view of the nozzle body from the direction of arrows II-II of Fig. 1 to illustrate the supply and distribution of the ignition and main fuel in the injector.

According to FIG. 1, the injection nozzle consists of an axially divided nozzle body 10 a , b and a holding body 11 abutting the nozzle body 10 a , b above it. The nozzle body 10 a , b and the holding body 11 are spanned by a nozzle clamping nut 12 provided with an inner cone. The two parts 10 a and 10 b of the nozzle body are fixed relative to each other by dowel pins 14 a , 14 b in the axial direction. In the part 10 of the nozzle body b is a first fuel-controlled valve needle 16 for the pilot fuel. For this purpose, the part 10 b of the nozzle body, a blind bore 15 b, the valve needle is in the sixteenth The needle in its upper part 16 b has a diameter which is equal to that of the blind bore 15 b . The lower part 16 a of the needle has a smaller diameter than the upper part 16 b . Via a pressure bolt 20 , the valve needle 16 is loaded by a spring 18 , the opening pressure being adjustable via a pressure adjusting disk (not shown).

The ignition fuel supply line is connected to a supply channel 22 leading through the holding body 11 . To the feed channel 22 , the fuel path of the ignition fuel is connected within the nozzle body. This consists of a pressure channel 24 , which is located in part 10 b of the nozzle body and opens into the control chamber 26 of the first valve needle 16 , which is formed by widening the blind bore 15 b and the transition region from the upper part 16 b in the pressure bore 15 b located valve needle 16 encloses the lower part 16 a . The peripheral surface of the valve needle 16 in the transition area from the upper part 16 b to the lower part 16 a corresponds to a pressure shoulder 28 of the first valve needle 16 , which is enclosed by the control chamber 26 . The fuel path is to attribute further extending from the control chamber 26 of up to be closed by the valve needle 16 blind hole 30 of the first valve needle 16 extending annular channel 24 a, which results as the annular gap between the blind hole 15 b and the valve needle 16, as well as from the valve seat 36 of the first valve needle 16 from the spray bore 34 leading into the combustion chamber 32 .

The first valve needle 16 presses against the valve seat 36 due to the force of the spring 18 and thus blocks the spray bore 34 . The pressure of the pilot fuel located in the pressure channel 24 acts within the control chamber 26 on the pressure shoulder 28 of the first valve needle 16 and opens the pressure upon reaching of the opening, so that the valve needle 16 opens the injection hole 34th

In addition, the injection nozzle in part 10 a of the nozzle body has a second fuel-controlled valve needle 38 . For this purpose, in part 10 a of the nozzle body there is a blind bore 15 a , which consists of an upper and a lower section, the upper section being larger in diameter than the lower section. The valve needle 38 inserted into the blind bore 15 a has an upper part 38 c , a middle part 38 b and a lower part 38 a , which tapers to the end. The diameter of the upper part 38 c and the diameter of the middle part 38 b corresponds to the diameter of the upper section or middle section of the blind hole 15 a , while the diameter of the lower part 38 a is smaller than the diameter of the lower section of the blind hole 15 a is. A control chamber 40 of the second valve needle 38 is designed like the control chamber 26 of the first valve needle 16 and encloses a peripheral surface of the valve needle acting as a pressure shoulder 44 of the second valve needle 38 in the transition region from its upper part 38 c to its central part 38 b . The control chamber 40 of this valve needle is connected via a pressure channel 42 according to FIG. 2 with an annular channel 43 , which connects the pressure channels 24 and 42 and to which the inlet channel 22 for ignition fuel leads. The pressure channel 42 is located in part 10 a of the nozzle body and ends in the control chamber 40 . The pressure of the ignition fuel reaching the control chamber 40 via the pressure channel 42 acts on the pressure shoulder 44 of the second valve needle 38 and raises it against the force of a spring 46 loading the second valve needle 38 , the tension of which is brought to the valve needle 38 via a pressure pin 48 and is adjustable via a (not shown) pressure adjusting disc. The control of the second valve needle 38 is carried out just like that of the first valve needle 16 by the pressure of the ignition fuel.

In addition to the control chamber 40 of the second valve needle is assigned a need in the fuel path for the main fuel collecting chamber 50 38, like the control chamber 40 is formed and is arranged downstream of the control chamber 40th The collecting chamber 50 encloses the valve needle 38 inserted into the blind bore 15 a in the transition region from the central part 38 b to the lower part 38 a . The (not shown) main fuel supply line is via an inlet channel 52 , which leads through the holding body 11 , with the main fuel path formed in the nozzle body, which runs in part 10 a of the nozzle body and extends as a supply channel 54 to the collecting chamber 50 , from this as an annular channel 54 a to the closable by the second valve needle 38 blind hole 56 , the annular channel 54 a as an annular gap between the blind hole 15 a and the lower part 38 a of the valve needle 38 results and from the blind hole 56 in the form of two or more spray bores 58 a , 58 b opens into the combustion chamber 32 .

When the second valve needle 38 is open, the main fuel passes through the supply channel 54 , the collecting chamber 50 , the annular channel 54 a , the blind hole 56 and the spray bores 58 a , b into the combustion chamber 32 . The main fuel has a pressure suitable for injection, which can be lower than the pressure of the ignition fuel required to control the two valve needles 16 and 38 .

Between the spray bores 58 a and 58 b of the second valve needle 38 and the spray bore 34 of the first valve needle 16 , a fuel-controlled needle valve is arranged transversely, which acts as an interrupter valve 59 and interrupts the injection of the ignition fuel during the main fuel injection. The needle valve has a valve needle 60 , at the end of which points to the blind hole 56 of the second valve needle 38 there is a control piston 62 which is guided in a bore 64 drilled in part 10 a of the nozzle body. The bore 64 is connected to the blind hole 56 of the second valve needle 38 via a pressure bore 66 . The tapered end of the valve needle 60 is laterally movable into the Spritzboh tion 34 for the ignition fuel. The spray hole 34 for the ignition fuel is divided into two sections 34 a , 34 b , of which the first section 34 a leads from the valve seat 36 for the first valve needle 16 to the valve seat 72 of the needle valve. The second section 34 b extends from the valve seat 72 to the combustion chamber 32 . Instead of only one second part of the channel 34 b, as shown in Fig. 1, a plurality of second sections are possible which open in difference directions union into the combustion space 32. When the valve needle 60 of the needle valve moves in the direction of its blind hole 61 , the spray hole for the ignition fuel is blocked by the valve needle 60 pressing against the valve seat 72 .

In the idle state, the needle valve is biased in the opening direction by a spring 68 . The spring 68 engages with its one end on a disk 70 which is located between the control piston 62 and the valve needle 60 and is fixedly connected to the latter. With its other end, the spring 68 is supported against the end face of a machined cylindrical cavity 69 in part 10 b of the nozzle body, which is directly connected to the bore 64 . The longitudinal axis of the cylindrical cavity 69 and the bore 64 coincide with the longitudinal axis of the valve needle 60 . With the help of a arranged between the spring 68 and the disk 70 pressure adjusting disk 71 , the tension of the spring 68 and thereby the response characteristic of the interrupter valve can be changed and adapted to the special requirements of an engine.

Due to the high pressure of the ignition fuel in the spray bore 34 when the first valve needle 16 is open, a small part of the ignition fuel passes along the valve needle 60 of the needle valve into the cylindrical cavity 69 . The cavity 69 is connected to the combustion chamber 32 via a bore 74 . The portion of the ignition fuel which reaches the cavity 69 as a leakage liquid can be discharged into the combustion chamber 32 via the bore 74 . The valve needle 60 of the needle valve and the control piston 62 of the needle valve are thus lubricated by the ignition fuel.

Ignition and main fuel injection during an injection cycle are described below. The increasing pressure of the ignition fuel at the beginning of the injection phase acts on the pressure shoulder 28 of the first valve needle 16 for the ignition fuel and opens it. Valve needle 60 of interrupter valve 59, which is in its rest position, does not block spray bore 34 for the ignition fuel, so that it is injected into combustion chamber 32 . Shortly after the opening of the first valve needle 16 , the further increasing pressure of the ignition fuel also opens the second valve needle 38 , which is set to a higher opening pressure. About the feed channel 54 , the ring channel 54 a and the blind hole 56 now passes through the spray holes 58 a , b main fuel in the combustion chamber 32nd Main fuel also passes through the pressure bore 66 into the part 67 of the bore 64 in which the control piston 62 of the interrupter valve 59 moves. The pressure of the main fuel thus acts on the acting as a control surface of the interrupter valve 59 end of the control piston 62, thereby being moved against the force of the spring 68 cut-off valve 59, and thereby the valve needle 60 of the breaker is pressed valve 59 against its valve seat 72 and thus blocks the spray hole 34 for the ignition fuel. Thus, despite the first valve needle 16 being opened, no ignition fuel is then injected into the combustion chamber 32 .

During this phase, only main fuel enters combustion chamber 32 . This can reduce the amount of ignition fuel per injection cycle. Only in a short transition phase from the beginning of the main fuel injection to the complete closure of the spray hole 34 through the valve needle 60 of the interrupter valve 59 both types of fuel get into the combustion chamber. The ignition fuel already injected into the combustion chamber 32 ignites the main fuel, the combustion of which is maintained until the end of the injection cycle with the main fuel injected further into the combustion chamber 32 . At the end of the injection phase dropping pressure of the ignition fuel first closes the second valve needle 38 , whereby the valve needle 60 of the interrupter valve 59 with the pressure of the main fuel now falling in the pocket hole 56 of the second valve needle 38 moves back to its starting position due to the spring 68 . Before this takes place, however, with a certain time delay Ver, so that the pressure of the ignition fuel has already dropped to below the opening pressure for the first valve needle 16 and thus no ignition fuel gets into the combustion chamber 32 towards the end of the injection phase. The time delay with which the movement of the valve needle 60 begins in its starting position is achieved in that the diameter of the cylinder 64 in which the control piston 62 of the interrupter valve 59 moves is substantially larger than the diameter of the pressure bore 66 , which results in a Throttling effect occurs when valve needle 60 is moved back.

With the help of the injection nozzle, the amount of ignition fuel per injection cycle can be reduced, thus saving ignition fuel. However, the amount of ignition fuel injected per one injection cycle is not constant, but rather depends on the instantaneous output required by the engine depending on the engine speed. A reliable ignition of the main fuel by the ignition fuel is made possible over the entire speed range of the engine, since both fuels are injected at the same time in a short period of time, the ignition fuel already in the combustion chamber at the start of the main fuel injection igniting the main fuel. Then the ignition fuel injection via the interrupter valve 59 is interrupted until the end of the injection phase by the main fuel which is still injected. In this way, a substantial amount of ignition fuel can be replaced by main fuel in all engine speed and load ranges, with a gentle main fuel ignition always taking place.

Finally, it should also be mentioned that the ratio of the injected fuel quantities during the cold start phase of the engine can be varied in a simple manner with the aid of the injection nozzle described. The engine operated at normal operating temperatures with ignition and main fuel can namely be operated almost exclusively with ignition fuel during the cold start by a throttle arranged in the fuel path of the main fuel, not shown, the pressure of the main fuel depending on a reference temperature can be that the break valve no longer interrupts the ignition fuel injection when the second valve needle is open. This ensures that almost exclusively ignition fuel enters the combustion chamber during the entire injection process and - due to the throttling in the main fuel path - the amount of main fuel per injection process is reduced. As soon as the engine temperature exceeds the reference value, the throttling effect in the main fuel path is canceled, so that the pressure of the main fuel is now sufficient to actuate the cut-off valve in such a way that no ignition fuel gets into the combustion chamber during the injection of the main fuel.

Claims (6)

1.Fuel injector for auto-ignition A dual-fuel injection internal combustion engine, with a fuel path formed in a nozzle body for an ignitable main fuel and a fuel path for an ignitable ignition fuel, one controlled by the pressure of the latter, arranged in the fuel path of the ignition fuel and at the same time entering the combustion chamber Internal combustion engine-controlling, with a needle seat cooperating first valve needle and also if controlled by the pressure of the ignition fuel, arranged in the path of the main fuel and thus controlling the entry of main fuel into the combustion chamber of the internal combustion engine, interacting with a needle seat, second valve needle, the injection of the ignition and the main fuel is controlled in such a way that the pilot fuel is controlled by separate injection holes that are assigned to the respective fuel path in such a way that with each injection cycle the ignition fuel is in front of the main fuel in the combustion chamber to arrive, characterized in that in the ge of the first valve needle ( 16 ) controlled fuel path of the ignition fuel a controlled by the pressure of the main fuel break valve ( 59 ) is arranged, which is biased in the opening direction by a biasing force and in its from the pressure of the main fuel against the biasing force causes the ignition fuel injection interrupts. 2. Fuel injection nozzle according to claim 1, characterized in that the interrupter valve ( 59 ) is designed as a needle valve, the valve needle ( 60 ) by blocking the needle seat of the first valve needle ( 16 ) downstream injection bore ( 34 ) interrupts the ignition fuel injection. 3. Fuel injection nozzle according to claim 2, characterized in that the spray bore ( 34 ) by the arrangement of the valve needle ( 60 ) of the interrupter valve ( 59 ) is divided into two sections ( 34 a , 34 b ), the needle-side ends in a valve seat ( 72 ) for the valve needle ( 60 ) which interacts with this in the closed position of the interrupter valve ( 59 ). 4. Fuel injection nozzle according to one of claims 1 to 3, characterized in that the pressure applied to the interrupter valve ( 59 ) by the main fuel via a pressure bore ( 66 ), seen in the spray direction behind the needle seat for the second valve needle ( 38 ) from the fuel path branches off for the main fuel. 5. Fuel injection nozzle according to one of claims 1 to 4, characterized in that the sub-breaker valve ( 59 ) between the spray bores ( 34 ; 58 a , 58 b ) of the two valve needles ( 16 , 38 ) and is arranged transversely to the latter. 6. Fuel injection nozzle according to one of claims 1 to 5, characterized in that the pre-tensioning force for the interrupter valve ( 59 ) is effected by a spring ( 68 ) and can be changed by a pressure adjusting disc ( 71 ).