Adjustment system for an injection pump, internal combustion engine and method for operating an internal combustion engine

Abstract

An adjustment system (1) for an injection pump (2) of an internal combustion engine (10) comprises an input-side transmission element (4), in particular a gear, driven by the crankshaft of the internal combustion engine (10), and a three-shaft transmission (3) actuated by the input-side transmission element (4), wherein the latter further comprises an adjustment shaft (8) as an input-side shaft and an output-side shaft (9) provided for coupling with the injection pump (2), and wherein a drive unit (13) exists for driving the adjustment shaft (8), which comprises a reduction gear (15), for example in the form of a wave gear.

Description

[0001] The invention relates to an adjustment system for an injection pump of an internal combustion engine, in particular an engine designed for the combustion of methanol and diesel fuel. Furthermore, the invention relates to an internal combustion engine, in particular a diesel engine, and to a method for operating an internal combustion engine that simultaneously burns two different fuels.

[0002] AT 361 255 B relates to a device for adjusting the injection timing of an injection pump in diesel engines. In particular, the device according to AT 361 255 B is intended for diesel engines in which each engine cylinder has its own injection pump-nozzle unit. In this configuration, the injection pump is driven by a camshaft via rocker arms. According to the teaching of AT 361 255 B, the rocker arm's pivot axis is fixed to a pivoting lever, with an adjusting element acting on the injection timing adjuster at one end of the pivoting lever.

[0003] German patent DE 1 213 666 B discloses a device for automatically adjusting the injection timing of a fuel injection pump for internal combustion engines. To change the injection timing, a control piston, actuated by a fluid control pressure dependent on the engine speed, is provided and is movable within a control cylinder. According to DE 1 213 666 B, changes in fuel viscosity should have no effect on the control mechanism.

[0004] Another injection timing adjuster is described in EP 1 167 723 B1. This adjuster also operates with a movable adjusting piston. EP 1 167 723 B1 describes in detail a sealing arrangement that includes a sealing element supported by a working piston.

[0005] DE 10 2022 133 656 A1 deals with the operation of an ammonia combustion engine. A known operating method is assumed in which a different fuel is used to ignite the ammonia. The operating method according to DE 10 2022 133 656 A1 aims to establish a predetermined molar ratio of ammonia to nitrogen oxides in the exhaust gas stream, regardless of the current operating point of the ammonia combustion engine.

[0006] Another internal combustion engine that burns ammonia is described in DE 11 2011 101 487 T5. In this case, too, a desired ratio of ammonia to nitrogen oxides is to be achieved through suitable control.

[0007] From WO 93 / 05 289 A2, an engine designed as a diesel engine is known, which is designed for the combustion of methanol. The engine according to WO 93 / 05 289 A2 operates with both a Roots supercharger and a turbocharger, and is equipped with intercooling.

[0008] DE 36 31 733 A1 discloses an adjustment system for an injection pump with a planetary gear as a three-shaft transmission. DE 102 05 034 A1 discloses a camshaft adjuster with a planetary gear, which is further developed in DE 10 2005 018 956 A1 and, in addition to a floating adjustment shaft, also has a planetary gear, which can be designed as a double planetary gear. DE 10 2008 050 826 A1 integrates a second reduction stage into an adjustment device for setting a variable compression ratio of an internal combustion engine.

[0009] The invention is based on the objective of providing methods of fuel injection that are more advanced than the prior art, particularly for large engines that can burn methanol, among other things.

[0010] This problem is solved according to the invention by an adjustment system for an injection pump of an internal combustion engine having a crankshaft, in particular a reciprocating piston engine, having the features of claim 1. According to claim 8, the engine equipped with the adjustment system is an internal combustion engine which is configured for the simultaneous combustion of different fuels. Furthermore, the problem is solved by a method for operating an internal combustion engine designed according to claim 10. The embodiments and advantages of the invention explained below in connection with the operating method also apply mutatis mutandis to the devices, i.e., the adjustment system and the entire internal combustion engine, and vice versa.

[0011] The adjustment system according to the application comprises an input-side transmission element, for example in the form of a gear or a sprocket, driven by the crankshaft of the internal combustion engine. In each case, the input-side transmission element actuates a three-shaft transmission. The three-shaft transmission further comprises an adjustment shaft as a second input-side shaft. The output-side shaft of the three-shaft transmission is a shaft intended for coupling with an injection pump. A drive unit, comprising a reduction gear, is provided for driving the aforementioned adjustment shaft. The adjustment unit thus comprises at least two transmissions in total.

[0012] By combining these transmissions, which provide for the actuation of an adjusting shaft of a three-shaft transmission via a reduction gear, a particularly favorable ratio can be achieved between the torque required by an actuator operating the reduction gear and the torque introduced into the output shaft, i.e., the torque with which the injection pump is activated. The adjusting shaft can be a shaft that does not rotate as long as the injection timing is not being adjusted.

[0013] For example, a further three-shaft gearbox is provided as a reduction gearbox, with the adjusting shaft located on its output side. This further three-shaft gearbox can, for example, be designed as a planetary gearbox. Alternatively, the further three-shaft gearbox can be a wave gear. Wave gears are characterized by a compact design and a high reduction ratio and operate with a flexible toothed gear element, which can, for example, be designed as a flex ring, i.e., a toothed ring without inwardly or outwardly projecting extensions. Variants of a toothed, elastically compliant gear element can also be used, which describe a hat or collar shape, i.e., have a radially outwardly directed flange. The use of a cup-shaped flexible toothed gear element is also possible.

[0014] Wave gears, which can be used without conceptual changes in the adjustment system according to the application, are used, for example, as actuators for electromechanical camshaft adjusters or as gearboxes for industrial robots. In this context, reference is made to documents DE 10 2016 219 943 A1, DE 10 2017 111 035 B3, WO 2005 / 080 767 A1 and DE 10 2018 132 400 A1. In the present case, the reduction gear, particularly in the form of a wave gear, can be designed as a self-locking gear. This means that the angular position of the adjusting shaft remains unchanged when no torque is applied to the reduction gear on the input side.

[0015] Instead of a three-shaft gearbox with the adjusting shaft on the output side, a worm gearbox can also be used at the corresponding point in the adjusting system. Worm gearboxes are characterized by a high gear ratio in a single gear stage and, at the same time, by a high power density, with the possibility of self-locking. In principle, an actuator with a worm gearbox is known, for example, from DE 27 27 293 A1.

[0016] The three-shaft transmission, actuated by the input-side transmission element driven directly or indirectly by the crankshaft, is specifically designed as a planetary gear set. Here, the input-side transmission element can, for example, interact directly with a ring gear of the planetary gear set, while the adjusting shaft, actuated via the reduction gear, is rotationally fixed to a sun gear of the planetary gear set. The planet carrier of the planetary gear set can be rotationally fixed to the shaft that actuates the injection pump. The injection pump is, for example, designed as a mechanical inline injection pump.

[0017] Regarding the interaction of the input-side transmission element with the three-shaft transmission, on the output side of which the injection pump is located, a wide variety of transmission principles are possible. For example, the input-side transmission element drives an element, in particular a ring gear, of the three-shaft transmission via a belt or chain drive. Similarly, the input-side transmission element and the aforementioned element of the three-shaft transmission can, for example, form a spur gear transmission.

[0018] Regardless of the type of gears used in the adjustment system, the three-shaft transmission actuated by the input-side transmission element can be configured to adjust the output-side shaft by at least 24 degrees. For example, the output-side shaft, i.e., the shaft that actuates the injection pump, has an adjustment range of 30 degrees. Generally, the reduction gear belonging to the adjustment system allows for the addition of an adjustment angle and thus stepless adjustment of the injection timing. When the reduction gear is not actuated, the three-shaft transmission, which is driven by the crankshaft of the internal combustion engine, provides a fixed gear ratio, in particular a 1:2 ratio – from an input-side speed, namely crankshaft speed, to half that speed.

[0019] An internal combustion engine configured according to claim 8, comprising an adjustment system configured according to claim 1, is designed for the simultaneous combustion of different fuels, wherein the adjustment system allows the dependence of the injection timing of exactly one of the different fuels on the crankshaft angle to be varied. In particular, the internal combustion engine is designed for the combustion of diesel fuel and methanol, wherein the injection pump in question is a diesel injection pump. Here, the diesel fuel is used to ignite the methanol. The mixing ratio of methanol to diesel can, for example, be 98:2. Operation of the internal combustion engine with ammonia and diesel is also possible.

[0020] The patented method for operating an internal combustion engine generally assumes that the engine simultaneously burns a fuel of the first type and a fuel of the second type, with the fuel of the second type being ignited by means of the fuel of the first type. This implies that the quantity of the fuel of the second type can be significantly greater than the quantity of the fuel of the first type.

[0021] To vary the interval between the injection of the primary fuel and the supply of the secondary fuel, a combination of two reduction gears is used. This interval can be expressed in degrees of crankshaft angle. Within this gear combination, a first reduction gear, designed as a three-shaft gear, has a first input element driven by the crankshaft of the internal combustion engine. The same three-shaft gear also has an electrically driven variable-pitch shaft as its second input element. Furthermore, there is an output shaft, i.e., a third shaft, of the three-shaft gear, which actuates an injection pump that delivers the primary fuel. A second reduction gear, in particular a worm gear, actuates the variable-pitch shaft of the first reduction gear, i.e., the three-shaft gear.Regarding the design of the second reduction gear, reference is made to the explanations concerning the device as applied for in the application.

[0022] An embodiment of the invention is explained in more detail below with reference to a drawing. The drawing shows, in schematic form: Fig. 1. An adjustment system for an injection pump of an internal combustion engine, namely a diesel engine that can be operated predominantly with methanol, Fig. 2 an unclaimed comparative example in which a diesel injection pump is operated in a simplified manner.

[0023] Unless otherwise stated, the following explanations refer to both the exemplary embodiment and the unclaimed comparative example. Corresponding or essentially equivalent parts are marked with the same reference numerals in both figures.

[0024] The internal combustion engine designated 10 is a marine diesel engine comprising an injection pump 2 in the form of a mechanical in-line injection pump for injecting diesel fuel. A coupling element, generally designated 6, is rotationally fixed to the crankshaft (not shown) of the internal combustion engine 10. A shaft 5, on which an input-side gear element 4 is located, rotates together with the coupling element 6. In the arrangements according to the Fig. 1 and Fig. 2. The input-side transmission element 4 is a gear which can be mounted directly on the crankshaft. This means that the shaft 5 can be in the form of the crankshaft, in which case the coupling element 6 for driving the transmission element 4 is not required.

[0025] In the exemplary embodiment, a connection is made between the input-side gear element 4 and the injection pump 2. Fig. 1 an adjustment system 1 and in the comparative example according to Fig. 2 a gear 16 is engaged. In both cases, the input-side gear element 4 is part of a spur gear transmission. The second element of the spur gear transmission, directly interacting with the input-side gear element 4, is, in the case of Fig. 1 a first input-side element 7 of a three-shaft transmission 3 and in the case of Fig. 2 the aforementioned gear 16 is provided.

[0026] The three-shaft gearbox 3, which is one of several gearboxes of the adjustment system 1, is, as shown from Fig.The planetary gear set 3, as shown in Figure 1, is designed as a planetary gear set. The first input element 7 of the planetary gear set 3 is its ring gear. The second input element of the planetary gear set 3 is an adjusting shaft 8, which is rigidly connected to the sun gear 17 of the planetary gear set 3 or is directly provided by the sun gear 17. The planet gears 11 of the planetary gear set 3, which mesh with both the internal teeth of the ring gear 7 and the external teeth of the sun gear 17 of the planetary gear set 3, are mounted on a planet carrier 12. The planet carrier 12 is non-rotatably connected to an output shaft 9 of the planetary gear set 3. The injection pump 2 is actuated by means of the output shaft 9.Optional compensating couplings within the adjustment system 1 or at interfaces between the adjustment system 1 and other components of the internal combustion engine 10 are not shown.

[0027] As long as the injection timing is not to be adjusted, the sun gear 17 remains in a constant angular position. Rotation of the adjusting shaft 8, and thus also of the sun gear 17, is possible with the aid of an electromechanical drive unit, designated 13. The drive unit 13 comprises an electric motor 14 and a reduction gear 15 actuated by it, which in this case is designed as a worm gear. Compared to a single-stage spur gear or a conventional planetary gear, the reduction gear 15 is characterized by an extremely high reduction ratio, for example, 1:30 or 1:60 or more. Alternatively, a wave gear can be used as the reduction gear 15, which represents a second three-shaft gear of the adjusting system 1 and comprises an elastic toothed gear element in a manner known in principle.

[0028] The output shaft of the reduction gear 15 is either identical to or rotationally fixed to the adjusting shaft 8. In this embodiment, the adjusting range of the adjusting shaft 8 is 30 degrees. Reference symbol list 1 adjustment system 2 Injection pump 3 three-shaft gears, planetary gears 4 input-side gear element 5 wave 6 coupling element 7. First input-side element of the planetary gear set, ring gear 8 second input-side element, adjusting shaft 9 output shaft of the planetary gear 10 Internal combustion engine 11 planetary gear 12 planetary carriers 13 Drive unit 14 Electric motor 15 Reduction gears, worm gears 16 gear 17 Sun wheel

Claims

[1] Adjustment system (1) for an injection pump (2) of an internal combustion engine (10) having a crankshaft, with an input-side transmission element (4) driven by the crankshaft of the internal combustion engine (10), and with a three-shaft transmission (3) actuated by the input-side transmission element (4), wherein the latter further comprises an adjustment shaft (8) as an input-side shaft and an output-side shaft (9) provided for coupling with the injection pump (2), and wherein a drive unit (13) exists for driving the adjustment shaft (8), which includes a reduction gear (15). [2] Adjustment system (1) according to claim 1, characterized by , that a further three-shaft gearbox is provided as a reduction gearbox (15). [3] Adjustment system (1) according to claim 1, characterized by , that a worm gear is provided as the reduction gear (15). [4] Adjustment system (1) according to any one of claims 1 to 3, characterized by, that the three-shaft gear (3) actuated by the input-side gear element (4) is a planetary gear. [5] Adjustment system (1) according to claim 4, characterized by , that the input-side gear element (4) interacts directly with a ring gear (7) of the planetary gear (3) and the adjusting shaft (8) is coupled non-rotatably to a sun gear (17) of the planetary gear (3). [6] Adjustment system (1) according to any one of claims 1 to 5, characterized by , that the reduction gear (15) is designed as a self-locking gear. [7] Adjustment system (1) according to any one of claims 1 to 6, characterized by , that the three-shaft transmission (3) actuated by the input-side transmission element (4) is designed to adjust the output-side shaft (9) by at least 24 degrees. [8] Internal combustion engine (10) configured for the simultaneous combustion of different fuels, comprising an adjustment system (1) designed according to claim 1, with which the injection timing of exactly one of the fuels can be adjusted. [9] Internal combustion engine (10) according to claim 8, characterized by , that it is intended for the combustion of diesel fuel as well as methanol, the injection pump (2) being a diesel injection pump. [10] Method for operating an internal combustion engine (10) which simultaneously burns a fuel of the first type and a fuel of the second type, wherein the fuel of the second type is ignited with the aid of the fuel of the first type, and wherein a combination of two reduction gears (3, 15) is used to vary the distance between the injection of the fuel of the first type and the supply of the fuel of the second type, within which a first reduction gear, namely a three-shaft gear (3), comprises a first input-side element (4) driven by a crankshaft of the internal combustion engine (10), and an electrically driven adjusting shaft (8) as a second input-side element, and an output-side shaft (9) which actuates an injection pump (2) supplying the fuel of the first type, as a third element, while the adjusting shaft (8) is actuated via a second reduction gear (15).

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