EP0989297B1 - Internal combustion piston engine - Google Patents

Description

The invention relates to a reciprocating internal combustion engine with several Cylinders, especially a two-stroke diesel engine.

Internal combustion engines, especially two-stroke diesel engines, are considered Main machine for ship drives but also as stationary systems for Electricity generation applied. These machines have a control shaft (Camshaft), which the fuel pumps are located on Actuate cams, and the gas exchange valves are also operated via them Control shaft via cams and bumpers or operated by cams Pumps, so-called hydraulic bumpers and piston drives actuated. The control shaft itself represents a major constructive Effort because of their length over the entire length of the engine, the large mass of the bearings to be lubricated by oil pressure Reversing mechanism for machines working in both directions of rotation and not least because of the required at least two (to four) Gears (and / or chains) for driving them through the crankshaft. There are also devices for damping torsional vibrations required.

The disadvantages of this design are that, on the one hand, the times for the start of injection, the opening and closing of the gas exchange valves are fixed by the respective cams and on the other hand to variable actuation of the gas exchange valves and / or for a variable The start of injection requires greater design expenditure.

From WO-A-98/11334 is a reciprocating internal combustion engine known in which an electronic Central unit controls the machine and one for each cylinder individual control module hydraulic gas exchange system.

The invention is based on the object Reciprocating piston engine with multiple cylinders while avoiding the to improve the disadvantages mentioned.

The advantages achievable with the invention can be seen in the fact that from the Application of electronic control a cheaper version the machine, a lower fuel consumption, a lower Pollutant emissions, low heating of the components, easier Maintenance and more reliable operation follows. In the further the operation the machine with a speed of less than 25% of the nominal speed improved, especially when driving slowly through narrow waters the continuous operation of the machine through improved concentricity allows.

The invention will now be described with reference to the accompanying drawings explained.

Fig. 1

eine schematische Darstellung einer Ausführungsform einer erfindungsgemässen Zweitakt-Dieselmotor;

Fig. 2

eine schematische Darstellung der Maschine gemäss Fig. 1;

Fig. 3

eine schematische Darstellung einer Ausführung einer Einspritzvorrichtung;

Fig. 4

eine schematische Darstellung eines Gaswechselsystems;

Fig. 5

ein Blockschema der Steuerung für die Maschine;

Fig. 6

eine schematische Darstellung einer anderen Ausführung einer Einspritzvorrichtung und

Fig. 7

eine Einzelheit A in Fig.4.

Show it:

Fig. 1

is a schematic representation of an embodiment of a two-stroke diesel engine according to the invention;

Fig. 2

a schematic representation of the machine according to FIG. 1;

Fig. 3

a schematic representation of an embodiment of an injection device;

Fig. 4

a schematic representation of a gas exchange system;

Fig. 5

a block diagram of the controller for the machine;

Fig. 6

a schematic representation of another embodiment of an injection device and

Fig. 7

a detail A in Fig.4.

Reference is made to FIGS. 1 to 3. Fig. 1 shows a two-stroke - diesel engine e.g. has four cylinders, not shown, and at which the interaction between gas exchange valve movement, Fuel supply and piston position is controlled electronically. The The machine has a first gear wheel 1 and one mounted on the crankshaft second gear 2, which meshes with the first gear. The second gear 2 is available for a mechanical drive for auxiliary energy and can at certain numbers of cylinders to drive the compensation of Second order mass forces are used. The machine contains High pressure pumps 3, preferably variable suction throttle pumps Delivery pressure for the fuel, a pressure regulator actuator 4, accumulators 5 for the fuel, which via pipes 6 with the high pressure pumps in Connect, pressure pumps 7, 107 for control oil and accumulators 8,108 for control oil, which is connected to the pressure pump 107 via a pipe 109 Connected, with only one pump, one accumulator and one Pipeline are shown. The high pressure pump 3 for the fuel driven by the second gear 2 and the pump 107 for the control oil is powered by an auxiliary motor.

As FIG. 2 shows, an injection system 11 is for a cylinder the accumulator 5 as well as the second accumulator 108 in connection stands and a gas exchange system 12 is provided, which with a third Accumulator 8 is connected.

The accumulators 5, 108 are tube-like components with or without Internals. In the case of the accumulators without internals, the Volume storage is preferably based solely on the elasticity of the storing media. At the accumulator 5 for the fuel is a Safety valve 16, the pressure in the accumulator on a fixed The maximum value is limited and a pressure sensor 17 is provided which measures the pressure in Accumulator detects.

The pressure pumps 7, 107 of the accumulator 8, 108 for working oil or control oil and pilot valves 14 each form a hydraulic system Control of the injection system and the gas exchange system, each Pump upstream of a filter 13 and each accumulator 8, 108 with one Pressure sensor 18, 19 is provided. In the inlet and outlet of the hydraulic Control system and in the fuel line between the battery 5 and Injection system 11, valves 40, 41, 42 are installed, which allow the Disconnect the injection system of each cylinder from the engine so that Repairs to the injection system are carried out with the engine running can.

The machine has an electronic control device. To the Determine the speed of the crankshaft and the crank angle Angle encoder 25 slip and mechanical means with the crankshaft backlash-free connected, between the second gear 2 and A gear (not shown) can be provided for angle sensors 25, so that the angle encoders rotate at the motor speed. There are two Reference encoder 26 is provided to ensure synchronism between the Monitor crankshaft and the angle encoder.

The control device contains at least one central unit 21, Control module 22 for each cylinder, a remote control 23 and one Speed controller 24. The central unit 21 and the control modules 22 are over a data bus networked form independent control units with one firmly assigned area of responsibility. The remote control 23 is with the Central unit connected to transmit signals. The pressure sensors 17, 18 and 19 are connected to central unit 21. The central unit 21 is also connected to the Pressure regulator actuator or pressure regulator actuators 4 of the high pressure pumps 3 for fuel and the pressure actuator or pressure actuators High pressure pump or pressure pumps 7 connected for working oil. The Control module 22 is connected to pilot valves 14 of injection system 11 and of the gas exchange system 12 and a measuring system 71 of the Gas exchange system and a measuring system 36 for volumetric Injection connected (Fig. 7).

The central unit 21 contains a memory in which all the engine relevant functions are stored. The control modules included also a memory in which those relating to the cylinder Functions are stored.

The central unit 21 forms the interface of the engine-relevant sensors, the speed controller and the remote control (operator interface) to the Control units of the cylinders. It is also used for regulating the pressures responsible for the various media.

According to the data supplied, the current and the desired operating state of the engine and communicated to the control modules 22 via the bus.

The control modules 22 determine this data in accordance with the Injection time, the injection quantity and the gas exchange control times taking into account the cylinder-specific offsets and dead times. Out For reasons of safety, the central unit 21 is in this embodiment provide redundant form. The failure of a control module 22 is shown in Purchased because, despite the failure of one cylinder, the maintenance is guaranteed.

As a variant with only one central unit 21, this can only the functions as a pressure regulator and as an interface to the operator include. These two functions are with one from the central unit independent, simple backup system. All other data and functions are integrated in each individual control unit 22, with which the Motor both in the event of failure of the central unit 21 and a control unit 22 remains operational.

The injection system 11 described below for each of the four Cylinders e.g. three fuel nozzles 31 and one injector 32 comprises and one or more pilot valves 14 are assigned.

3 shows an embodiment of the injection device 32 in the basic position. The injection device contains a metering piston 34, a valve slide 35 and a displacement sensor system 36 for monitoring the position of the metering piston in order to realize a volumetric injection. The metering piston 34 is designed as a differential piston. The metering piston 34 is arranged in a metering chamber 37, into which a connection channel to the accumulator 5 opens on the one hand and which is connected to a channel 140 on the other hand. This channel connects a chamber 141 and a chamber 142, the length of the channel advantageously being designed to be short in order to keep dynamic pressure differences small and to prevent the valve slide opening automatically. A blind bore 143 opens into the chamber 141. A spring 145 is arranged in the chamber 141, which is supported on the one hand on the valve slide 35 and on the other hand in the chamber 141 and is intended to hold the valve slide in the basic position. A valve seat 38 ^I and two control edges 38 ^II and 38 ^{IV are} formed on the valve slide 35. The valve spool 35 is arranged in the housing and forms gap seals 38 ^III , 38 ^V and 39 with it. The valve spool 35 has a piston 144 which projects into the blind bore. A return duct for fuel branches off into the injection channel and is provided with an orifice 30, so that when the nozzle needle is stuck, no fuel is injected because the fuel flows through the orifice into the unpressurized space.

The pilot valve is designed as a changeover valve and must be one have positive overlap between the switch positions to a The second accumulator 108 is idling when it is stuck To prevent valve pistons.

Furthermore, a unit, not shown, is provided to each cylinder in Dependence of the load and / or the crank angle with lubricant supply.

The function of the injection system is described below. In the basic position of the valve slide 35, fuel flows from the accumulator 5 via the control edge 38 ^{IV of} the valve slide 35 into the metering chamber 37. Because of the area difference, the metering piston 34, which is charged with battery pressure on both sides, runs into its defined end position. The metering piston 34 and the valve slide 35 block the flow of fuel from the accumulator 5 to the fuel nozzles 31 and prevent the accumulator 5 from leaking if, for example, the nozzle needle of a fuel nozzle is stuck. Furthermore, fuel flows via the channel 140 into the chambers 141 and 142, so that the same pressure prevails in these. This has the advantage that the valve slide can only be actuated on the basis of a control command.

The pilot valve 14 is switched by the control module 22, so that control oil from the accumulator 108 reaches the control piston 39 of the valve spool 35 and displaces it. Because of the positive overlap between the valve seat 38 ^I and the control edge 38 ^II, 38 ^IV closes before 38 ^II opens. When the control edge 38 ^II is open, there is a connection between the metering chamber 37 and the fuel nozzles 31. By displacing the valve slide 35, the piston 144 is displaced into the blind bore 143, the braking edge of the movement of the valve slide being initiated by the control edge 147 and in a particularly advantageous manner damping is achieved.

The rear of the metering piston is connected to the accumulator 5 and the pressure in the latter shifts fuel to the fuel nozzle 31 until the fuel volume corresponds to the product of the metering piston area times the metering piston stroke in order to obtain the speed value specified by the speed controller, ie a volumetric fuel metering is realized. The displacement of the metering piston 34 is detected by means of the knife system 36 and the control module 22 switches the pilot valve 14 over, so that in the valve slide 35 the control edge 38 ^II closes first and then the control edge 38 ^IV opens. As a result, the fuel supply to the fuel nozzle 31 is interrupted.

A valve slide 35 is assigned to each fuel nozzle 31, so that the Fuel nozzles for each cylinder controlled independently and all injection options, such as easy Injection - single or multiple interrupted injection - injection times of different lengths at the individual fuel nozzles can also be carried out with cyclic or stochastic swapping (Fig.2). It is advantageous if the fuel nozzle is damped for the nozzle needle is provided. For this purpose there is a chamber 148 and a channel 149 formed in the housing, which connects the chamber with the leak line. The nozzle needle is at the end facing away from the valve seat with a piston 150 provided that protrudes into the chamber. As a low-cost version, a only valve slide 35 all fuel nozzles of an engine cylinder serve. With the system described, these can also be used Heavy and residual oils usual for engines are used.

As shown in FIG. 4, the gas exchange system 12 contains a device 51 with a separating piston 56 and a control piston 52, each one Gas exchange valve 53 are assigned. The separating piston 56 is intended to separate the hydraulic system (working oil) from the lubricating oil circuit and the movement of the outlet valve 53 in the area of the end positions dampen. The pilot valve 14 draws working oil in a switching position from the accumulator 8 and switches the control piston 52 into one of two possible positions in which the gas exchange valve 53 due to a Valve air spring 61 reaches the "closed" position. In doing so, a Drive piston 54 displaced over the valve stem and displaces oil in a pipe 55, which in turn displaces a piston 56 and almost in a defined starting position. The piston 56 in turn displaces working oil via the control piston 52 into the line 57 to one Collection tank. During the time until the next switching of the Gas exchange valve 53 is due to leakage losses and not shown constant ventilation lost oil via a line 58 and check valve 59 refilled and thereby piston 56 completely in brought the defined starting position.

If the pilot valve 14 is placed in the other position, one moves Compression spring 60, the control piston 52 in the other position, so that Working oil can flow through the pilot valve 14, and connects via the control piston 52 the side of the piston 56, that of the pipeline 58 is turned away, with the accumulator 8. The piston 56, the Pipeline and the drive piston 54 flowing working oil opens it Gas exchange valve against the one that is still in the cylinder of the engine Gas pressure and the valve air spring 61.

Because only at the beginning of this movement, in the case of using the Gas exchange valve as an outlet valve, a large force must be present to open against the remaining pressure in the cylinder is the Drive piston 54 is designed as a stepped piston 65, 66. At the beginning of Distance of the valve movement affects the larger piston 65 with its larger cross-sectional area and generates the force that is necessary Open gas exchange valve 53. In the further course of the valve movement A smaller force is sufficient to complete the gas exchange valve 53 To have the stroke carried out. The larger piston 65 moves against you Stop 67, the movement shortly before reaching this stop is braked by a damping, not shown. With this arrangement the piston 65 and 66 is removed from the second accumulator 8 Minimized amount of working oil.

The measuring system 71 contains a step cone 72 and redundant sensors 78 to detect and move the gas exchange valve Generate measurement signal that is sent to the control module 22. The The controller detects whether the gas exchange valve movements meet the setpoints intervenes in the event of incorrect switching and prevents e.g. the next Fuel injection on the cylinder in question. That way ensures that e.g. an n-cylinder engine operated with (n-1) cylinders can be. As FIG. 7 shows, the step cone 72 has a first one conical section 79, an adjacent cylindrical Section 76 and a subsequent second conical section 77 on, the cone angle of the first and second section as possible is chosen large in order to fully utilize the measuring range of the sensors. The first section 79 detects the opening behavior of the valve and enables assess the damping while opening the valve. The second Section 77 records the closing behavior of the valve and enables it Assess damping while closing the valve. With smaller ones Engines with less exhaust valve lift and lower tolerances are also a version with a simple cone, which can cover the whole Valve stroke covers with only one cone section.

If for some reason the gas exchange valve 53 is not quite closes, the stepped piston 65 and 66 is not in its Starting position, i.e. there is too much oil in line 55. If now the piston 56 delivers the full amount of oil, the gas exchange valve would 53 with the air spring 61 undefined at high speed against the Valve guide bush pressed, which could lead to an engine accident. To prevent this, disc springs are provided, which are by Compress the kinetic energy of the mass of the gas exchange valve record and thereby prevent damage to the engine. Not one shown constant ventilation of the system between the pipe 55th and the drive piston 54 and the unavoidable leakage losses ensure that if the hydraulic control fails during the "Open" phase of the gas exchange valve after some time (minutes) closes automatically.

Because the piston 56 separates the hydraulic system from the lubricating oil circuit the risk of contamination of the working oil circuit largely eliminated because when the cylinder is covered, the working oil circuit filled with finely filtered oil does not have to be opened. In the line between the second Accumulator 8 and control piston 52, as well as in the make-up line 58 Check valve 59 and in the drain line 57 are valves 73, 74, 75 built-in, which allow the gas exchange system of each individual Separate cylinders from the engine so that repairs to the Exhaust valve control can be carried out with the engine running.

As shown in FIG. 5, the control device can have two central units 21 have, one as a main unit and the other as a reserve unit is operated. The central units 21 are with each control module 22 and the sensors 25, 26 connected by means of a bus system. The sensors 25, 26 are like this arranged that all at a certain angular position of the crankshaft Encoder signals are checked for their validity via logic. Becomes a If a fault is found, the defective encoder can also be found. each Control unit 22 controls this using the data from central unit 21 Injection system, the gas exchange system, and the start air valves 28. Falls an inlet controller 27, water injection or sequential Piston lubrication is provided, this is also from the Control module 22 controlled. In normal operation, the two share in FIG. 5 illustrated buses the tasks in the sense that the one only for Communication between the modules is used, the other only for transmission the current crankshaft position and the speed. In emergency operation, that is Defective on one of the buses, the engine can also be less accurate can only be operated with the bus intact.

If there is a malfunction or failure of the electronic control, For example, damage to both angle sensors 25, so that the Central unit 21 no longer correctly or the required electrical signals can no longer generate, an emergency system is required to Maintain the operability of the large diesel engine. As Fig.5 shows can do this in the internal combustion engine according to the invention Pulse control shaft 91 are provided, which the electrical Control signals for the pilot units 14 on the duty cycle of the engine generated coordinated. The pulse control shaft 91 is a separate unit that is mechanically connected to the crankshaft of the machine.

6 shows another embodiment of the injection device. The Pressure pump 7, the accumulator 8 and pilot valves 14 form one hydraulic system for controlling the injection and actuating the Gas exchange.

The injection device contains a metering piston 81, a valve slide 82, a control valve 83 and a displacement sensor system 84 for monitoring the position of the metering piston in order to achieve volumetric injection realize. The metering piston is designed as a pressure booster. A Pressure pump 86 pumps the fuel into the pressure booster 81 and that Control valve 83 blocks flow to the injectors.

In the basic position, the valve spool is closed, the pressure booster in the starting position and the control valve closed. The means of Pressure pump in the pressure booster fuel keeps the Pressure booster in the starting position. Is the control spool by the hydraulic system operated with the pilot valve 14a flows under pressure standing control oil in the pressure booster and moves it. The Pressure booster increases the pressure in the fuel to injection pressure. It will noted that for each cylinder one or more Pilot valves 14 or control valves 83 can be provided.

The reciprocating piston internal combustion engine contains an injection system volumetric injection for each cylinder, one or more High pressure pumps to supply fuel, at least one Pressure pump for supplying control medium, one for each Fuel, tax and working oil, which with the pumps as well as with the Gas exchange system communicates with a hydraulic system Organs for controlling the injection and actuation of the gas exchange, one or more angle encoders and a control device with one Central unit and several electronic control modules to the Starting air supply, injection, gas exchange and central lubrication to control.

In normal operation, the machine is controlled purely electronically.

Claims (18)

1. Reciprocating piston combustion engine having a plurality of cylinders, in particular a two stroke diesel engine, including an injection system (11) for the volumetric injection of fuel by means of metering pistons for each cylinder, a gas exchange system (12) for each cylinder, a plurality of pumps (3, 7, 107, 15) for the supply of fuel and control medium, one or more accumulators (15; 8; 108) for fuel and control medium which are in connection with the pumps and with the injection system and/or with the gas exchange system, a hydraulic system with members (14) for controlling the injection and the gas exchange, a lubricating apparatus for each cylinder, one or more angle sensors (25, 26) and a control apparatus with a central unit (21) for the machine as well as an autonomous electronic control module (22) for each cylinder in such a manner that, through the electronic control module (22), the fuel nozzles for the fuel supply can be individually controlled, and the gas exchange can be regulated and the starting air supply can be controlled.
2. Internal combustion engine in accordance with claim 1, in which a high pressure pump (4) is preferably provided with a suction restrictor control for the fuel.
3. Internal combustion engine in accordance with any one of the preceding claims, in which the pump (7) for the working medium is connected to the crankshaft.
4. Internal combustion engine in accordance with any one of the preceding claims, which has an auxiliary drive for the pump (7) for working medium.
5. Internal combustion engine in accordance with any one of the preceding claims, in which accumulators (5, 8, 108) with or without inbuilt members are provided.
6. Internal combustion engine in accordance with any one of the preceding claims, in which a safety valve (16) for the accumulator (5) for fuel is provided in order to hold the pressure in the accumulator to a set maximum value.
7. Internal combustion engine in accordance with any one of the preceding claims, in which respective valves (40, 41, 42; 73, 74, 75) are provided in the forwarding lines for fuel and control medium in order to separate the injection system (11) and the gas exchange valve (13) of each individual cylinder from the engine, with it being possible to actuate the valves manually.
8. Internal combustion engine in accordance with any one of the preceding claims, in which a differential piston (34) or a stepped piston (81) is provided for metering the fuel.
9. Internal combustion engine in accordance with any one of the preceding claims, which has a measurement system in order to regulate the movement of the metering piston (34, 81).
10. Internal combustion engine in accordance with any one of the preceding claims, in which a central lubrication with a pressure regulation is provided.
11. Internal combustion engine in accordance with any one of the preceding claims, in which a clocked central lubrication is provided.
12. Internal combustion engine in accordance with any one of the preceding claims, in which an electrically controllable valve for starting air is provided for each cylinder.
13. Internal combustion engine in accordance with any one of the preceding claims, having a pulse control shaft (23) which is connected to the crankshaft in order to control the machine in the event of a failure of the control apparatus.
14. Internal combustion engine in accordance with any one of the preceding claims, in which a plurality of angle sensors (25) which are arranged on a shaft in order to produce a signal representing the crankshaft angle, and a plurality of reference sensors (26) with a control logic are provided in order to monitor the signal representing the crankshaft angle.
15. Internal combustion engine in accordance with any one of the preceding claims, in which a control module is associated with each cylinder and is connected in a signal transmitting manner to the control apparatus.
16. Internal combustion engine in accordance with any one of the preceding claims, having a measurement system in order to regulate the movement of the gas exchange valve.
17. Internal combustion engine in accordance with any one of the preceding claims, in which an inlet control (27) is provided for each cylinder.
18. Internal combustion engine in accordance with any one of the preceding claims, characterized in that filters (13) are provided which are placed ahead of the pumps (7, 107) for control oil.

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