JP2019090407A - Fuel injection nozzle and fuel injection method for large diesel engine and large diesel engine - Google Patents

Abstract

To propose a fuel injection nozzle for a large diesel engine.SOLUTION: A fuel injection nozzle includes: a nozzle head (3) having at least one nozzle hole (30); a fuel pipe (4) which may inject a fuel into a pressure chamber (5); a valve element having a valve piston (61) and a nozzle needle (62); and a valve seat (11) which is designed to cooperate with the nozzle needle (62). The fuel injection nozzle is provided with an upper chamber (9), a lower chamber (10), a first supply pipe (21), a first discharge pipe (31), a second supply pipe (22), a second discharge pipe (32), and a first control valve (7) and a second control valve (8). The first control valve (7) and the second control valve (8) alternately operate independently of each other. Further, a fuel injection method and a large diesel engine are proposed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a fuel injection nozzle and a fuel injection method for a large diesel engine according to the preambles of independent claims in each category, and to a large diesel engine.

  Large diesel engines (e.g. vertical sweep, two-stroke large diesel engines) are often used as drive units for ships. Alternatively, the ship is used even while at rest (e.g. driving a large generator to generate electrical energy). These engines typically operate for a significant amount of time in continuous operation, which places high demands on operating safety and availability. As a result, in particular, it is an important criterion for the operator to lengthen the maintenance interval of the working material, reduce the wear, and handle it economically.

  Over the years, the quality of exhaust gases has become increasingly important and has become another major issue. As a result, combustion of diesel oil or other fuels, as well as conventional heavy oil combustion (which is highly contaminated with pollutants), has become a more important issue, especially for large two-stroke diesel engines . For example, compliance with emission thresholds is increasingly difficult, technically more complex, and associated with costs. That is, compliance with the threshold is no longer economically feasible.

  Thus, in practice, engines capable of operating at least two different fuels have long been needed. These may be, for example, two different liquid fuels, or liquid and gaseous fuels. Such engines are usually referred to as multi-fuel engines and it is possible to switch from one fuel to another during operation. Known liquids or gaseous fuels which can alternatively be burned in a large-scale diesel engine with multiple fuels include, in addition to heavy oil, marine diesel oil and diesel oil (specifically alcohols such as methanol or ethanol); Natural gas such as LNG (liquefied natural gas) or emulsions or suspensions are included.

  As an example, an emulsion called Multiphase Superfine Atomized Residue (MSAR) can be mentioned. These are essentially heavy hydrocarbon emulsions (e.g. bitumen, heavy oil etc), or water, and are produced in special processes. Another example is, for example, suspensions made from coal dust and water, which are also used as fuels for large diesel engines.

  A special type of multi-fuel engine is one that is commonly referred to as a "dual fuel engine", which can operate on two different fuels. Gases, for example natural gas such as LNG (liquefied natural gas), burn in gas mode, but suitable liquid fuels, such as diesel and heavy oil, can burn in the same engine in liquid mode

  Within the framework of this application, the term "large diesel engine" can be operated not only by diesel operation characterized by auto-ignition of fuel but also by Otto operation characterized by active ignition of fuel, Or, it also refers to a multi-fuel large engine, a dual fuel engine, and a dual fuel large engine that can be operated in these two mixed forms. The term "large diesel engine" also includes such large engines operable with at least two different fuels, at least one of these different fuels operating the engine in diesel operation. Is suitable.

  Modern large diesel engines are usually fully electronically controlled and typically supply fuel to the cylinders, such as heavy oil or diesel, with a common rail system for fuel injection using an accumulator for the fuel Including. At least one fuel injection nozzle is provided for each cylinder to inject fuel into the combustion chamber of each cylinder. In most cases, several fuel injectors (e.g. two or three) may be provided for each cylinder. Each fuel injection nozzle is connected to this pressure accumulator and comprises a nozzle body and a nozzle head, which usually projects into the combustion chamber of the cylinder. The nozzle head (also called an atomizer) usually comprises several nozzle holes through which fuel is injected into the combustion chamber. In order to initiate or terminate the injection process, the fuel injection nozzle is provided with a movable valve body, which cooperates with the valve seat to open and close the passage to the nozzle hole. In order to start the injection process, the valve body is lifted from the valve seat by a stroke against the force of the spring, and fuel can flow into the nozzle bore by the injection pressure. In order to terminate the injection process, the valve body is in sealing contact with the valve seat and the passage to the nozzle bore is closed.

  The injection process is controlled electronically, for example by applying a current to a solenoid controlled valve, which causes a corresponding stroke movement of the valve body of the fuel injection nozzle. At the end of the injection, the force of the spring pushes back the valve body into sealing contact with the valve seat.

  While injection systems for such large diesel engines have been demonstrated in practice, there is still room for improvement. One of the challenges is the problem of inertia or response time of the injection system. The electrical and electronic signals that cause the start or end of the injection process can be generated as sharp, clear and accurate timing signals, but due to the physical characteristics of the injection system, when actually injecting fuel into the cylinder: When opening or closing the passage between the valve body and the valve seat, both the time and the side slope deviate from the electronic signal. Specifically, there is a problem that the opening and closing of this passage is too slow, that is, the reaction time of the fuel injection nozzle is too long. Such long reaction times can adversely affect the economical, efficient and low emissions operation of large diesel engines. This is especially true when the engine is cold starting or when the engine is operating at low load.

  Several measures have been attempted to reduce these reaction times, ie to shorten the process of opening and closing the passage between the valve seat and the valve body, ie to accelerate, but these measures are often compromised It means only. Since the opening and closing initiated by the control valve is performed via the throttle, specifically the throttle pipe through which the fluid (for example, fuel) flows, the closing is delayed by accelerating the opening, or vice versa. , Which is usually the case.

Starting from this state of the art, the object of the present invention is that the switching time of the fuel injection nozzle is particularly short, ie from the open state (flow connection to the nozzle head is open) to the closed state (nozzle head). It is to propose a fuel injection nozzle for a large diesel engine, in which the switching time to the closed flow connection (and vice versa) is particularly short.
A further object of the invention is to propose a corresponding fuel injection method and a large diesel engine.

  The object of the invention for solving this problem is characterized by the features of the independent claims of the respective category.

  According to the invention, a fuel injection nozzle for a large diesel engine is proposed. A nozzle head having at least one nozzle hole for injecting fuel into a combustion chamber; a fuel pipe capable of injecting fuel into a pressure chamber; and a valve body, a spring mounted and connected to a valve piston and the valve piston A valve body having a nozzle needle and a valve seat designed to cooperate with the nozzle needle, said valve seat being in the open state the flow connection between the pressure chamber and the nozzle head Open by stroke, in the closed state the nozzle needle seals and includes a valve seat cooperating with the valve seat to close the flow connection between the pressure chamber and the nozzle head, limited by the top of the valve piston An upper chamber, and a lower chamber limited by the lower portion of the valve piston, and a first supply pipe connecting the upper chamber and the fuel pipe; A first exhaust pipe connecting the chamber to the first outlet of fuel, a second supply pipe connecting the lower chamber to the fuel pipe, and a second exhaust pipe connecting the lower chamber to the second outlet; A first control valve, in the closed position closing both the second supply pipe and the first discharge pipe, and in the open position the second supply pipe and the first discharge pipe There is further provided a first control valve which opens both, a second control valve, which in the closed position closes the second outlet pipe and in the open position opens the second outlet pipe Control valves are further provided, and the first control valve and the second control valve operate independently and alternately.

  An upper chamber is provided above the valve piston and a lower chamber is provided below the valve piston, and two control valves can control the inflow to and the outflow from the upper and lower chambers. This design achieves a significant reduction of the switching time.

  The term "switching time" refers to both the opening time required for the valve body to be switched from the closed state to the open state and the closing time required for the valve body to be switched from the open state to the closed state. Point to

  Embodiments of the present invention allow the upper part of the valve piston to be released from the pressure of the fuel while at the same time applying pressure to the lower part of the valve piston to switch from the closed state to the open state, significantly shortening the open time. Connect. On the contrary, it is possible to release the pressure from the lower part of the valve piston and switch from the open state to the closed state at the same time as the fuel pressure is applied to the upper part of the valve piston, thereby shortening the closing time significantly.

  According to a preferred embodiment, the first control valve and the second control valve are each designed as a spring-loaded solenoid valve which switches from the closed position to the open position against the force of the spring when an electric current is applied. It is done. For this purpose, the first control valve and the second control valve are preferably designed as monostable switching elements. This means that each control valve has only one stable state, i.e. a closed position. The other state, i.e. the open position, is maintained only while current is applied to the control valve. When no current is applied to the control valve, the control valve is automatically returned to its stable or closed position by spring biasing.

  For practical reasons, the first control valve and the second control valve are preferably each designed as a sliding valve with a valve slide.

  In a preferred embodiment, a third supply pipe is provided connecting the upper chamber to the fuel pipe, and in the closed position the second control valve closes the third supply pipe and in the open position the third supply pipe Open. At this time, when switching from the open state to the closed state by the second control valve, not only the second discharge pipe for releasing the pressure in the lower chamber is opened, but also the third supply pipe is opened. Pressurized fuel can flow further from the pipe through the supply pipe into the upper chamber, so that the pressure rises faster in the upper chamber. This can further shorten the closing time.

  According to a preferred embodiment, the valve piston comprises an upper piston and a lower piston connected to each other hydraulically and / or mechanically by means of a connecting element, the upper piston forming the upper part of the valve piston and the lower part The piston forms the lower part of the valve piston.

  In this design of the valve piston, it is advantageous for structural reasons if the lower piston is designed as a hollow piston and receives a spring, which mounts the valve piston.

  Of course, this design as a hollow piston is not essential, for example it is also possible to design the lower piston as a full piston, ie without a cavity. In such a design, the spring mounting the valve piston is preferably mounted on the upper end surface of the lower piston.

  In the design of a valve piston comprising an upper piston and a lower piston, a compensation pipe is provided to equalize the pressure between the lower part of the upper piston and the upper part of the lower piston, through which the fuel is discharged Is more preferred. This means that as the fuel enters the area between the upper and lower pistons, the compensating pipe prevents pressure build up in this area.

  According to a particularly preferred embodiment, the stroke of the valve body is adjustable, and the flow cross section of the open and open flow connection can be varied between the pressure chamber and the nozzle head. This means that the stroke of the valve body can be adjusted to any value between zero (closed state) and the maximum stroke, the maximum stroke corresponds to the maximum open state, and the pressure chamber and the nozzle head The flow connection between has a maximum flow cross section along the valve seat. This stroke is preferably adjusted by operating the first control valve during the injection process. This adjustment is performed not by a single pulse having a wavelength corresponding to the desired injection time, but by a plurality of short pulses, whereby the second connection pipe and the first discharge pipe are opened for a short time. This may be supported by multiple short term actuations of the second control valve.

  The plurality of short term actuations of the first control valve (and preferably also the second control valve) causes the valve body to float or migrate at an intermediate position between the closed and the maximum open states during the injection process. It will be possible to keep doing. In this way, the open flow cross section of the flow connection between the pressure chamber and the nozzle head can be adjusted along the valve seat to any value between zero and a maximum value. In contrast to the known solutions in which the stroke of the valve body is a constant value, with the fuel injection nozzle according to the invention, a variable stroke of the valve body is realized, ie a change between closed and maximum open state can do.

  This variable stroke of the valve body is advantageous, for example, in part-load operation of a large diesel engine. In particular, the smaller amount of fuel required per injection process compared to full load operation allows the valve body to be operated with smaller strokes, less pressure at lower pressure per time interval Fuel is injected. This is also advantageous as the opening and closing times can be further reduced due to the smaller stroke of the valve body.

  Furthermore, the variable stroke makes it possible to change the stroke between two or more non-zero values during the injection process. For example, during the injection process it is possible to move from the first intermediate position to a second intermediate position (which is different from the first intermediate position) or to move the valve body to the maximum open state.

  This variable stroke of the valve body allows for the initiation of injection to optimally adjust the injection process to the respective operating conditions (e.g., fuel type and characteristics, or load range at which the engine operates). In addition to the and injection periods, it means that other parameters (i.e. the variable stroke of the valve body and hence the variable pressure of the injection) will also be available. In particular, virtually any injection profile can be realized which means a time course of the amount of fuel injected. Pre-injection is also possible. In particular, the variable stroke of the valve body allows optimal injection, which in turn enables particularly economical, efficient, low emissions and wear reduction operation of large diesel engines.

  From a practical point of view, the connecting pipe and the exhaust pipe, where pressurized fuel is injected into the lower chamber or the upper chamber, or fuel is discharged from the lower chamber or the upper chamber, are designed as throttle pipes, respectively It is preferable to throttle the flow of fuel through the pipe. Specifically, the following measures are preferred for this purpose.

  The second supply pipe has a diameter of 50% or less, preferably 25% or less, of the diameter of the fuel pipe.

  The first feed pipe has a diameter smaller than the diameter of the second feed pipe.

  The third feed pipe has a diameter approximately the same as the diameter of the second feed pipe.

  The second discharge pipe has a diameter between the lower chamber and the second control valve and is smaller than the diameter of the second supply pipe.

  These measures can be realized individually or in any combination. It is preferred that all the means described above are realized.

Furthermore, the invention proposes a fuel injection method for a large diesel engine. This method is
Providing a fuel injection nozzle designed according to the invention;
Activating the first control valve to start the injection process;
Activating the first control valve, and optionally optionally a plurality of second control valves, during the injection process.

  As explained above in connection with the fuel injection nozzle according to the invention, the advantageous variable stroke of the valve body during the injection process is achieved by activating the first control valve multiple times, possibly the second control valve. Can be achieved.

  According to a preferred embodiment, the valve body is at least temporarily maintained at an intermediate position between the closed state and the maximum open state during the injection process.

  Furthermore, a large diesel engine, in particular a vertical scavenged two-stroke large diesel engine, is proposed according to the invention, which large diesel engine comprises a fuel injection nozzle designed according to the invention, ie the invention It is operated by the fuel injection method by

  Specifically, this large diesel engine can be designed as a multi-fuel engine capable of operating as at least two different fuels, in particular dual fuel engines, and is operated with liquid fuel, preferably heavy oil or diesel oil Can be switched from liquid mode to gas mode upon actuation, and vice versa.

  Further advantageous measures and embodiments of the invention result from the dependent claims.

  The invention will now be described in more detail with reference to embodiments and the drawings.

1 is a schematic longitudinal sectional view of an embodiment of a fuel injection nozzle according to the present invention.

  Within the framework of the present application, relative location designations such as "lower", "upper", "directly below", "upper" etc. will be understood so that they always refer to the usual position of use.

  FIG. 1 shows a schematic longitudinal sectional view of an embodiment of a fuel injection nozzle for a large diesel engine according to the present invention, the fuel injection nozzle being indicated generally by the reference numeral 1. In particular, the fuel injection nozzle 1 is suitable for a vertical scavenging two-stroke large-sized diesel engine. It will be appreciated that the fuel injection nozzle 1 is also suitable for other large engines, for example a four-stroke large diesel engine or a large engine, and can be operated with other liquid fuels.

  FIG. 1 shows the fuel injection nozzle 1 in its normal operating position.

  Large diesel engines are equipped with a plurality of cylinders, for example 6, 2, 12 or more cylinders, in a manner known per se. Each cylinder is provided with a piston, which is disposed back and forth along the traveling surface of the cylinder between top dead center and bottom dead center, and the upper portion of the piston is a combustion chamber 50 together with a cylinder cover. Limit (Figure 1). Fuel (for example, heavy oil) is injected into the combustion chamber 50 by the fuel injection nozzle 1.

  The fuel injection nozzle 1 is part of an injection system, which is designed, for example, as a common rail injection system. The injection system comprises at least one, but usually several (e.g. two or three) fuel injection nozzles 1 per cylinder, for injecting fuel into the combustion chamber 50 and fuel injection nozzles 1 is usually placed on the cylinder cover

  The structure and individual components of large diesel engines, such as injection systems, gas exchange systems, exhaust systems or turbocharger systems for supplying scavenging or charging air, as well as control and monitoring systems of large diesel engines, are known to those skilled in the art. It is well known and need not be described further here.

  Modern heavy duty diesel engines are fully electronically controlled and monitored. An engine control unit (not shown) controls and monitors all functions of the large diesel engine, for example the operation of the outlet valve for gas exchange or the fuel injection process. These various functions are controlled or regulated by electrical and electronic signals used to control the corresponding components of the engine. In addition, an engine control unit receives information from various detectors, sensors or measuring devices.

  Common rail injection systems that supply fuel (e.g., heavy oil) to the combustion chamber 50 of each cylinder include a pressure accumulator (not shown), also commonly known as an accumulator. This pressure accumulator keeps the fuel under high pressure, which essentially corresponds to the injection pressure at which the fuel is injected into each combustion chamber 50. This pressure accumulator is usually designed as a tubular container extending along all the cylinders of a large diesel engine. High pressure fuel is supplied to the pressure accumulator by one or more fuel pumps. For example, the pressure of the fuel in the pressure accumulator may be 700 to 900 bar, but may be higher or lower. The booster pump (connected to the fuel tank) transfers the fuel to the fuel pump.

  The fuel injection nozzles 1 are each connected to a pressure accumulator via a pressure pipe, and the fuel to which the injection pressure is applied can be transported from the pressure accumulator to the fuel injection nozzle 1. Furthermore, a flow rate limiting valve can be provided between the fuel injection nozzle 1 and the pressure accumulator, which can prevent, for example, unintended continuous injection due to a malfunction.

  An embodiment of the fuel injection nozzle 1 according to the invention and its operation, which is schematically shown in FIG. 1, will now be described in more detail.

  The fuel injection nozzle 1 extends in the radial direction defined by the longitudinal axis L of the fuel injection nozzle 1 and comprises a nozzle body 2 and a nozzle head 3, and the nozzle head 3 is provided at the lower end of the fuel injection nozzle 1 , Is connected to the nozzle body 2. This nozzle head 3 can be designed as a separate part connected to the nozzle body 2. Alternatively, the nozzle head 3 may be an integral part of the nozzle body 2. The nozzle head 3 has at least one nozzle bore 30, generally a plurality of nozzle bores 30, through which fuel can be introduced into the combustion chamber 50 of the cylinder. The fuel injection nozzle 1 is attached to the cylinder cover of the cylinder, for example, so that the nozzle head 3 protrudes into the combustion chamber 50 of the cylinder.

  Preferably, the fuel injection nozzle 1 further comprises a fuel pipe 4, which is designed as a bore in the nozzle body 2. The fuel pipe 4 can be connected to a pressure pipe (not shown), by means of which the fuel injection nozzle 1 is connected to a pressure accumulator (not shown) for fuel and an injection pressure is applied. Fuel flows into the fuel pipe.

  The fuel pipe 4 extends to a pressure chamber 5 in the nozzle body 2, through which the pressurized fuel can be introduced into the pressure chamber 5. The pressure chamber 5 is substantially annular in shape.

  The fuel injection nozzle 1 further includes a valve body 6, which has a valve piston 61 and a nozzle needle 62 connected to the valve piston 61. The nozzle needle 62 is axially disposed below the valve piston 61. The nozzle needle 62 extends in the pressure chamber 5 along the axial direction A. In this embodiment, the valve piston 6 comprises an upper piston 611, a lower piston 612 and a connecting element 613, which connecting element 613 is arranged between the upper piston 611 and the lower piston 612, these two pistons 611, 612 are mechanically connected and / or hydraulically connected or coupled to one another.

  The valve piston 61 has an upper portion 614 and a lower portion 615, which form an axial end surface of the valve piston 61. In the embodiment described herein, the upper piston 611 forms the upper portion 614 of the valve body 61 and the lower piston 612 forms the lower portion 615 of the valve piston 61.

  In the embodiment shown in FIG. 1, the lower piston 612 is designed as a hollow piston, ie with a central recess, into which the connecting element 613 extends. The spring 12 is disposed in this central recess of the lower piston 612 to load or apply pressure to the valve body 6.

  Alternatively, it is of course also possible to design the lower piston 612 as a full piston, ie without a central recess. The lower end portion of the spring 12 preferably rests on the upper portion of the lower piston 612.

  The valve body 6 comprises a valve piston 61 having an upper piston 611, a lower piston 612 and a connection element 613 and a nozzle needle 62, and consists, for example, of several parts. The valve body 6 is movable back and forth in the axial direction A.

  The lower end of the nozzle needle 62 is designed to cooperate with the valve seat 11, which is arranged directly below the pressure chamber 5 and adjacent to the pressure chamber 5. Preferably, the lower end of the nozzle needle 62 is designed like a cone or frustum, and the valve seat 11 is also designed like a cone or frustum so that the nozzle needle 62 and the valve seat 11 seal.

  In the closed state, the nozzle needle 62 is sealed and cooperates with the valve seat 11 so that the flow connection between the pressure chamber 5 and the nozzle head 3 is closed and the fuel reaches the nozzle head 3 from the pressure chamber 5 I can not In the open state, the axial stroke A of the valve body 6 (upwardly as shown) opens the flow connection between the pressure chamber 5 and the nozzle head 3 and allows the nozzle needle 62 and the valve seat 11 to open. Fuel flows from the pressure chamber 5 to the nozzle head 3 and the nozzle hole 30.

  The nozzle needle 62 has a taper 621 in the area located in the pressure chamber 5 so that the fuel under the injection pressure in the pressure chamber 5 can exert an upward force on the valve body 6. The lower piston 612 of the valve body 6 is designed as a hollow piston and arranged such that the spring 12 is received by this lower piston 612 and biases the valve body 6 in the direction of the valve seat 11. This means that the spring 12 exerts a downward force on the valve body 6 and pushes the valve body 6 in the direction of the valve seat 11.

  Furthermore, an upper chamber 9 is provided in the nozzle body 2, which is arranged above the valve piston 61 and limited by the upper portion 614 of the valve piston 61. Furthermore, a lower chamber 10 is also provided in the nozzle body 2, which is arranged below the valve piston 61 and limited by the lower portion 615 of the valve piston 61.

  The fuel injection nozzle 1 includes a first supply pipe 21, a second supply pipe 22, a first discharge pipe 31, and a second discharge pipe 32, and each of these pipes 21, 22, 31, 32 is Preferably, it is designed as a bore in the nozzle body 2.

  The first supply pipe 21 connects the upper chamber 9 and the fuel pipe 4. The second supply pipe 22 connects the lower chamber 10 and the fuel pipe 4. The first exhaust pipe 31 connects the upper chamber 9 and the first outlet 91, and fuel can flow from the upper chamber 9 to the first outlet 91. The second exhaust pipe 32 can connect the lower chamber 10 to the second outlet 92 and allow fuel to flow from the lower chamber 10 to the second outlet 92. The first outlet 91 and the second outlet 92 are connected to a fuel supply (for example, a fuel storage tank) via a recirculation (not shown) so that through these two outlets 91, 92 Outflowing fuel returns to the fuel supply.

  In the embodiment described herein, a third supply pipe 23 is further provided, which is also preferably designed as a bore in the nozzle body 2 and which comprises the upper chamber 9 and the fuel pipe 4. Connecting. The third supply pipe 23 is different from the first supply pipe 21.

  The fuel injection nozzle 1 comprises a first control valve 7 and a second control valve 8 in order to control or regulate the flow of pressurized fuel through the various pipes 21, 22, 23, 31, 32. The two control valves 7, 8 are designed as electronically or electrically controllable switching valves with an open position and a closed position, respectively.

  The two control valves 7, 8 can be operated independently of one another, ie can be switched independently of one another. This means that if the first control valve 7 is in the open position, the second control valve 8 can optionally be in the open or closed position, and if the first control valve 7 is in the closed position: It also means that the second control valve 8 can optionally also be in the open or closed position. Thus, the two control valves 7, 8 can be actuated or switched independently of one another. Regardless of the position of the two control valves 7 or of the control valve 8 (open or closed position), the other control valve 8 or 7 can, as required, be moved back and forth between its open and closed positions. It can be switched. Thus, the first control valve 7 and the second control valve 8 can be actuated or activated independently of one another. Thus, the two control valves 7 and 8 can be switched separately.

  When the first control valve 7 is in the closed position, both the second supply pipe 22 and the first exhaust pipe 31 are closed so that no fuel flows between them. When the first control valve 7 is in the open position, both the second supply pipe 22 and the first discharge pipe 31 are opened, so that the fluid flows through these pipes 22, 31 and the first outlet 91. It can flow through.

  When the second control valve 8 is in the closed position, the second exhaust pipe 32 is closed so that fuel can not flow through the second outlet 92. When the second control valve 8 is in the open position, the second exhaust pipe 32 is open, which allows fuel to flow through the second exhaust pipe 32 to the second exhaust port 92.

  The passage of the third supply pipe 23 is also controlled by the second control valve 8. When the second control valve 8 is in the closed position, the second control valve 8 closes the third supply pipe 23, and the fuel is introduced from the fuel pipe 4 into the upper chamber 9 via the third supply pipe 23. I can not do it. When the second control valve 8 is in the open position, the third supply pipe 23 is open, and fuel can flow from the fuel pipe 4 to the upper chamber 9 through the third supply pipe 23.

  The first control valve 7 and the second control valve 8 are each designed as spring-loaded solenoid valves 7, 8, which have the force of the springs 71, 81 when current is applied. It is preferable to change from the closed position to the open position. It is particularly preferred that the first control valve 7 and the second control valve 8 are each configured as a monostable switching valve. This means that each first control valve 7 or second control valve 8 has only one stable state, ie a closed position. The other state (i.e., the open position) is maintained only while current is applied to the control valve 7 or the control valve 8. If no current is applied to the control valve 7 or the control valve 8, the control valve 7 or 8 automatically returns to its stable or closed position by the biasing of the spring.

  For this purpose, the first control valve 7 and the second control valve 8 are preferably designed as slide valves with a valve slide 72 or a valve slide 82. Each valve slide 72 or valve slide 82 is biased by the spring 71 or 81 in the direction of the closed position. That is, as long as no current is applied to the control valve 7 or the control valve 8, the respective control valve 7 or the control valve 8 is held in its closed position by the respective springs 71 or 81. An electromagnet 73 or electromagnet 83 is provided to move the respective control valve 7 or control valve 8 from the closed position to the open position, and when current is applied to these electromagnets, the respective valve slide 72 or 82 , Thereby switching the respective control valve 7 or control valve 8 from the closed position to the open position and holding the control valve 7 or the control valve 8 in the open position until the application of the control valve 7 or the control valve 8 is stopped.

  The second supply pipe 22 extends from the fuel pipe 4 to the inlet of the first control valve 7 and then from the outlet of the first control valve 7 to the lower chamber 10. The third supply pipe 23 extends from the fuel pipe 4 to the inlet of the second control valve 8 and then from the outlet of the second control valve 8 to the upper chamber 9. The first exhaust pipe 31 extends from the upper chamber 9 to the other inlet of the first control valve 7 and then from the other outlet of the first control valve 7 to the first outlet 91. The second exhaust pipe 32 extends from the lower chamber 10 to another inlet of the second control valve 8 and then from another outlet of the second control valve 8 to the second outlet 92.

  Furthermore, a compensation pipe 41 for pressure compensation is provided between the lower side of the upper piston 611 and the upper side of the lower piston 612. On the other hand, the compensation pipe connects the space directly below the lower portion of the upper piston 611 and the space above the upper portion of the lower piston 612. Meanwhile, the compensation pipe 41 is connected to the third outlet 93. As a result, no pressure is applied to the space directly below the lower portion of the upper piston 611 and the space above the lower piston 612, and no pressure difference occurs between the two spaces.

  Next, the function of the fuel injection nozzle will be described. FIG. 1 shows the fuel injection nozzle 1 or the valve body 6 in a closed state in which injection is not performed. The first control valve 7 and the second control valve 8 are in the closed position. The pressure of the fuel in the fuel pipe 4 is applied to the upper chamber 9 via the first supply pipe 21. Since the first exhaust pipe 31 and the second supply pipe 22 are closed, the fuel may flow out of the upper chamber 9 through the first exhaust pipe 31 and also through the second supply pipe 22. It does not flow into the lower chamber 10.

  The pressure in the pressure chamber 5 is essentially the same as the fuel pipe 4 and this is the injection pressure. Since the pressure in the upper chamber 9 is also the same as the pressure in the fuel pipe 4, the combined force of the spring force by the spring 12 and the force applied by the pressure in the upper chamber 9 of the upper portion 614 of the valve piston 61 is in the pressure chamber 5. Exceeds the combined force of the forces applied to the nozzle needle 62 and the taper 621 by the pressure of the nozzle needle 62 and the force applied to the lower chamber above the lower portion 615 of the valve piston 61. As a result, the nozzle needle 62 of the valve body 6 is pushed into the valve seat 11 and sealed, whereby fuel does not enter the pressure head 5 into the nozzle head 3.

  In order to start the injection process into the combustion chamber 50 of the working cycle of each cylinder, the engine control unit sends a signal to apply an electric current to the electromagnet 73 of the first control valve 7. In doing so, the valve slide 72 of the first control valve 7 is drawn against the force of the spring 71. As a result, the first control valve 7 switches from the closed position to the open position. The second control valve 8 is not actuated (i.e. no current is applied) and remains in the closed position.

  Since the first control valve 7 is in the open position, both of the second supply pipes 22 are open and the pressurized fuel passes from the fuel pipe 4 through the second supply pipe 22 to the lower part. Flows into the chamber 10 and the first exhaust pipe 31 so that fuel flows simultaneously from the upper chamber 9 through the first exhaust pipe 31 to the first outlet 91, thereby releasing the upper chamber 9 from pressure Be done.

  The pressure of the fuel from the fuel pipe 4 is applied to the lower chamber 10 and the pressure in the upper chamber 9 is released, so that the force exerted by the fuel pressurized in the lower chamber 10 on the lower portion 615 of the valve piston 61 The combined force exerted by the fuel in the pressure chamber 5 on the nozzle needle 62 and the taper 621 exceeds the force exerted on the valve piston 61 by the spring 12. As a result, the valve body 6 is lifted in the axial direction A by one stroke, and the nozzle needle 62 is also lifted from the valve seat 11 accordingly. In this open state, the flow connection between the pressure chamber 5 and the nozzle head 3 is open and pressurized fuel flows from the pressure chamber 5 into the nozzle head 3 and through the nozzle bore 30 to the combustion chamber of the cylinder It is injected into 50.

  At the beginning of the injection, the lower chamber 10 is pressurized and at the same time the upper chamber 9 is relieved of pressure, so the opening time is particularly short, ie from the closed state to the open state by the stroke of the valve body 6 Switching is conveniently performed in a very short time.

  In order to end the injection to the combustion chamber 50, the application of the current of the first control valve 7 is stopped. Since no current is supplied to the electromagnet 73 of the first control valve 7, the valve slide 72 is returned to the rest position by the force of the spring 71 of the first control valve 7, whereby the first control valve 7 The open state is switched to the closed state, and both the second supply pipe 22 and the first discharge pipe 31 are closed.

  At the same time, a current is applied to the electromagnet of the second control valve 8 by a signal to the second control valve 8, and the second control valve 8 switches from the closed position to the open position. In the open position, the second control valve 8 opens both second exhaust pipes 32, through which fuel can flow from the lower chamber 10 to the second outlet 92, and the third The supply pipe 23 of the Thereby, the pressurized fuel from the fuel pipe 4 can additionally flow into the upper chamber 9 through the third supply pipe 23.

  As a result, the second control pipe 7 closes the second supply pipe 22 and the first discharge pipe 31, and the second control valve opens the second discharge pipe 32 and the third supply pipe 23. Be done. As a result, on the one hand, the lower part 615 of the valve piston 61 is released from the pressure very quickly because fuel can flow out of the lower chamber 10 through the second exhaust pipe 32. On the other hand, the pressurized piston can flow into the upper chamber 9 from the fuel pipe 4 through both the first supply pipe 21 and the third supply pipe 23, so the valve piston can be very quickly Pressure is applied to the upper portion 614 of 61.

  The pressure increase in the upper chamber 9 and the pressure reduction in the lower chamber 10 simultaneously occur, and additionally, the action of the spring 12 presses the nozzle needle 62 against the valve seat 11 and the force for sealing contact again increases. The valve body 6 switches from the open state to the closed state, and the flow connection between the pressure chamber 5 and the nozzle head 3 is interrupted.

  As the lower chamber 10 is released from pressure and at the same time pressure is applied to the upper chamber 9 to terminate the injection, the closing time is particularly short. That is, the switching from the open state to the closed state caused by the valve body 6 takes place advantageously in a very short time.

  After the injection is completed (that is, immediately after the nozzle needle 62 is closed and sealed and cooperates again with the valve seat 11), the application of the current to the second control valve 8 is ended and returned to the closed state. The second control valve 8 closes both the second discharge pipe 32 and the third supply pipe 23. Primarily, the second control valve 8 functions to release the lower chamber 10 from pressure as soon as possible to accelerate the switch from open to closed, i.e. to reduce the closing time. Optionally, i.e. the presence of the third supply pipe 23, the second control valve 8 also serves to accelerate the pressure amplification in the upper chamber 9 when switching from open to closed is performed. Do.

  In this way, the fuel injection nozzle 1 is characterized in that a very short switching time, that is to say both switching from closed to open and change from open to closed, takes place very quickly. This enables particularly economical and efficient low emissions and low wear operation of large diesel engines.

  In particular, the fuel injection nozzle 1 is suitable for a fuel injection method in which the fuel injection nozzle 1 is operated with the variable stroke of the valve body 6.

  As described above, by operating the first control valve 7 once, the injection process of one operation cycle of the cylinder can be performed. For this purpose, the first control valve 7 is actuated with a single signal or pulse, whereby the start of the signal determines the start of injection and the length of the signal determines the injection duration. At the start of the signal, a current is applied to the electromagnet 73 of the first control valve 7 and at the end of the signal the current application of the electromagnet 73 of the first control valve 7 is ended. As described above, by operating the second control valve 8, the switch from the open state to the closed state can be supported or accelerated.

  However, it is also possible to activate the first control valve 7 several times during the injection process with one signal or pulse each if the individual signals have a length considerably shorter than the desired injection length. In such a multiple actuation of the first control valve 7, the first control valve 7 has to switch back and forth several times between the closed position and the open position during the injection process.

  By means of such multiple actuation or pulsing, the valve body 6 is in a position between the closed state (nozzle needle 62 in sealing contact with the valve seat 11) and the maximum possible stroke of the valve body 6 during the entire injection process. It is possible to move or keep floating. This means that the valve body 6 can be maintained at an intermediate position between the closed state and the maximum open state during the injection process.

  Thus, by actuating the first control valve 7 several times, the stroke of the valve body 6 can be adjusted during the injection process, and the pressure chamber 5 and the nozzle head 3 along the valve seat 11 can be adjusted. The open flow cross section of the flow connection between can be varied.

  It will be appreciated that this floating or migration retention of the valve body 6 at an intermediate position between the closed state and the maximum open state can be supported by appropriate actuation of the second control valve 8.

  The injection process can be optimized as much as possible by this method of operating the valve body 6 with variable strokes. For example, it applies to the current load for operating a large diesel engine, or to the characteristics of a fuel, to mention two examples.

  For example, it is possible to carry out the entire injection process in one stroke of the valve body 6, which corresponds to an intermediate position between the closed state and the maximum open state.

  It is also possible to change the stroke of the valve body during the injection process (i.e. at the start of injection), first adjusting the first stroke of the valve body 6 and then the first stroke during this injection process And the second stroke of the valve body 6 different from

  By actuating the first control valve 7 and optionally the second control valve 8 it is possible to change the stroke of the valve body, so that virtually any injection profile for the injection process can be realized it can. An injection profile refers to the passage of time of the amount of fuel injected during the injection process.

  For example, during the injection process, it is also possible to realize pre-injection or to increase the stroke of the valve body 6 in several steps.

  In order to achieve the desired injection profile or to adjust the desired stroke of the valve body 6, the length of the individual signals and / or the individual at which the first control valve 7 is actuated during the injection process It is possible to adjust the time interval between the signals of to obtain the desired injection profile.

  In order to achieve a particularly good and quick switching of the fuel injection nozzle 1 from the closed state to the open state and vice versa, the various supply and discharge pipes 21, 22, 23, 31, 32 are preferably Each is designed as a bore in the nozzle body 2 and has a throttling effect, the strength of this throttling effect being preferably adjusted by the diameter of the respective pipe 21, 22, 23, 31, 32. Specifically, the following measures may be advantageous with regard to the throttling effect.

  The diameter of the second supply pipe 22 is 50% or less, preferably 25% or less, of the diameter of the fuel pipe 4. The diameter of the second supply pipe 22 corresponds, for example, to about 20% of the diameter of the fuel pipe 4.

  The diameter of the first feed pipe 21 is smaller than the diameter of the second feed pipe 22. The diameter of the first feed pipe 21 is at most 50% of the diameter of the second feed pipe 22.

  The third feed pipe 23 has a diameter at least approximately equal to the diameter of the second feed pipe 22.

  The second discharge pipe 32 has a diameter smaller than the diameter of the second supply pipe 22 in the region between the lower chamber 10 and the second control valve 8. The diameter of the second discharge pipe 32 in the region is about 80% of the diameter of the second supply pipe 22.

  The first discharge pipe 31 and the second discharge pipe 32 have respective regions downstream of the first control valve 7 or the second control valve 8 (ie, each control valve 7, 8 and the first outlet 91). Between, and between the second outlet 92), there should be little or no throttling effect. In these regions, for example, the first exhaust pipe 31 or the second exhaust pipe 32 may have at least the same diameter as the fuel pipe 4.

  Furthermore, it may be advantageous to connect the lower chamber 10 to the fuel pipe 4 via the throttle pipe 42. For this purpose, the throttle pipe 42 should have a much stronger throttling effect than the second exhaust pipe 32. For example, the diameter of the throttle pipe 42 may be up to 50% of the diameter of the second exhaust pipe 32 in the region between the lower chamber 10 and the second control valve 8.

Claims (15)

A fuel injection nozzle for a large diesel engine,
A nozzle head (3) having at least one nozzle hole (30) capable of injecting fuel into the combustion chamber (50);
A fuel pipe (4) capable of injecting fuel into the pressure chamber (5);
A valve body (6) fitted with a spring (12) and having a valve piston (61) and a nozzle needle (62) connected to said valve piston (61);
A valve seat (11) designed to cooperate with the nozzle needle (62), and in the open state the flow connection between the pressure chamber and (5) the nozzle head (3) is the valve Opened by the stroke of the body (6) and in the closed state the nozzle needle (62) seals tightly and cooperates with the valve seat (11), the pressure chamber (5) and the nozzle head (3) Closing the flow connection between the valve seat (11) and
An upper chamber (9) limited by the upper portion (614) of the valve piston (61);
A lower chamber (10) limited by the lower portion (615) of the valve piston (6);
A first supply pipe (21) connecting the upper chamber (9) to the fuel pipe (4);
A first exhaust pipe (31) connecting said upper chamber (9) to a first outlet (91) of fuel;
A second supply pipe (22) connecting the lower chamber (10) to the fuel pipe (4);
A second discharge pipe (32) connecting the lower chamber (10) to a second outlet (92);
A first control valve (7), which in the closed position closes both the second supply pipe (22) and the first discharge pipe (31), and in the open position the second supply There is further provided a first control valve (7) which opens both the pipe (22) and the first discharge pipe (31),
A second control valve (8), which in the closed position closes the second exhaust pipe (32) and in the open position opens the second exhaust pipe (32) (8) is further provided,
A fuel injection nozzle, wherein the first control valve (7) and the second control valve (8) operate independently and alternately.   The first control valve (7) and the second control valve (8) are each configured as a spring-biased solenoid valve, and when a current is applied, the solenoid valve is a spring (71; 81). The fuel injection nozzle according to claim 1, wherein the closed position is switched to the open position against a force.   3. The fuel injection as claimed in claim 1, wherein the first control valve (7) and the second control valve (8) are each designed as a sliding valve with a valve slide (72; 82). nozzle.   A third supply pipe (23) connecting the upper chamber (9) to the fuel pipe (4) is provided, the second control valve (8) being in the closed position the third supply pipe The fuel injection nozzle according to any one of claims 1 to 3, wherein (23) is closed and the third supply pipe (23) is opened in the open position.   The valve piston (61) comprises an upper piston (611) and a lower piston (612) hydraulically and / or mechanically connected to each other by a connecting element (613), the upper piston being the valve 5. The upper part (614) of a piston (61), the lower piston (612) forming the lower part (615) of the valve piston (61) Fuel injection nozzle.   The fuel injection nozzle according to claim 5, wherein the lower piston (612) is designed as a hollow piston and receives the spring (12) on which the valve piston (61) is mounted.   A compensation pipe (41) is provided to equalize the pressure between the lower portion of the upper piston (611) and the upper portion of the lower piston (612), and fuel can be drained through the compensation pipe. The fuel injection nozzle according to any one of claims 5 to 6.   The stroke of the valve body (6) is adjusted so that the flow cross section of the flow connection open in the open state can be changed between the pressure chamber (5) and the nozzle head (3) The fuel injection nozzle according to any one of claims 1 to 7, which is possible.   9. A device according to any one of the preceding claims, characterized in that the second supply pipe (22) has a diameter not exceeding 50%, preferably not exceeding 25%, of the diameter of the fuel pipe (4). Fuel injection nozzle.   The fuel injection nozzle according to any one of the preceding claims, wherein the diameter of the first supply pipe (21) is smaller than the diameter of the second supply pipe (22).   The fuel injection nozzle according to any one of claims 4 to 10, wherein the third supply pipe (23) has a diameter approximately equal to the diameter of the second supply pipe (22).   The second discharge pipe (32) has a diameter between the lower chamber (10) and the second control valve (8), and the diameter of the second discharge pipe is the second The fuel injection nozzle according to any one of claims 1 to 11, which is smaller than the diameter of the supply pipe. A fuel injection method for a large diesel engine,
Providing a fuel injection nozzle (1) designed according to any one of the preceding claims;
Starting an injection process by operating the first control valve (7);
Operating the first control valve (7) and optionally the second control valve (8) multiple times during the injection process.   The fuel injection method according to claim 13, wherein the valve body (6) is at least temporarily held at an intermediate position between the closed state and the maximum open state during the injection process. It is a large diesel engine, especially a vertical scavenged two-stroke large diesel engine,
A heavy duty diesel engine comprising a fuel injection nozzle (1) designed according to any one of the preceding claims or operated according to the fuel injection method according to any one of the claims 13-14. .