Crankshaft for an inline two-cylinder engine

Abstract

Crankshaft (1) for a parallel two-cylinder engine (10), comprising a first crankpin (2) and a second crankpin (3), wherein there is an offset angle (100) between the first crankpin (2) and the second crankpin (3) which is greater than 90° and less than 180°.

Description

[0001] The present invention relates to a crankshaft for an inline two-cylinder engine. The invention further relates to an inline two-cylinder engine comprising such a crankshaft. Finally, the invention relates to a motorcycle comprising such an inline two-cylinder engine.

[0002] Various two-cylinder motorcycle engines are known from current technology. Motorcycle engines must meet a multitude of requirements. Firstly, an engine is a load-bearing component. Therefore, there is only minimal damping between the engine and the motorcycle frame, making smooth, vibration-free operation essential. Furthermore, the engine sound is an important aspect of motorcycles. The sound of a V-twin engine is often used as a benchmark in this regard.

[0003] Furthermore, parallel twin-cylinder engines that can be used to power a motorcycle are known from the prior art. Such engines usually have a crankshaft. 1 , as in Fig. 1 shown, on. The crankshaft 1 includes two outer shaft journals 5 as well as a central shaft pin 4 for the crankshaft bearing 1 in crankshaft bearings. Furthermore, the crankshaft 1 a first crankpin 2 and a second crankpin 3 up. The first crankpin is involved. 2 and the second crankpin 3 The cylinders are arranged in parallel. If the inline two-cylinder engine operates according to the four-stroke cycle, it is specifically designed that the firing interval between the two cylinders is set at 360°. However, with such a crankshaft, a complex compensation system for engine vibrations generated by masses rotating in the same direction is often necessary.

[0004] To avoid such vibrations, it is also known from the prior art to use crankpins 2 , 3 to arrange them offset from one another. It is particularly known to arrange the first crankpin in this way. 2 offset by 180° from the second crankpin 3 to attach. In this way, a counter-rotation is created by the crankpins. 2 , 3 driven pistons, thereby achieving vibration compensation. This allows for very low vibration operation. However, the opposing masses of the crankshaft lead to 1 and the driven piston to a tilting moment as well as a pivoting moment, which is perceived by a motorcycle rider as a disturbing vibration, just like vibrations.

[0005] Finally, it is known that the first crankpin 2 at 90° to the second crankpin 3to offset the firing order, thereby achieving, in particular, the firing interval of a V2 engine with a 90° cylinder angle. This has particular advantages in terms of the engine's sound. However, the vibration behavior is affected here due to the irregular mass distribution of the crankshaft. 1 very disadvantageous, so compensatory measures must be taken, as otherwise a motorcycle rider would perceive disturbing vibrations.

[0006] The object of the invention is to provide a crankshaft for an inline two-cylinder engine which, with simple and cost-effective manufacture and assembly, enables low-vibration and acoustically pleasing operation of the inline two-cylinder engine, especially in four-stroke operation.

[0007] This problem is solved by the features of the independent claim. The dependent claims contain preferred embodiments of the invention.

[0008] The solution is achieved by a crankshaft for a parallel-twin engine, featuring a first crankpin for actuating the first piston and a second crankpin for actuating the second piston. The crankshaft is designed with an offset angle between the first and second crankpins, greater than 90° and less than 180°. Surprisingly, this arrangement has been shown to significantly reduce the proportions of free inertial forces and free inertial moments in a parallel-twin engine equipped with this crankshaft. This, in turn, reduces vibrations transmitted from the engine to the frame, particularly that of a motorcycle. This leads to improved comfort and a reduction in the effort and costs associated with measures required to enhance comfort.The reduced vibration tendency of the inline twin-cylinder engine equipped with such a crankshaft relieves stress on the connection points between the engine and frame. This simplifies the design of the engine, the frame, and the connections themselves. Thus, both complexity and cost are reduced. However, a person skilled in the art would expect increased vibration of the inline twin-cylinder engine with a crankpin offset in the described area, since vibrations due to the oscillating and rotating masses of the 90° crankpin offset are superimposed on the tilting and pivoting moments of the 180° crankpin offset. For these reasons, crankpin offsets in the aforementioned areas have been avoided in the prior art.

[0009] In an advantageous embodiment of the invention, the offset angle is greater than 100°, in particular greater than 110°, preferably greater than 120°, and most preferably greater than 130°. Alternatively or additionally, the offset angle is less than 170°, in particular less than 160°, more preferably less than 150°, and most preferably less than 140°. With an offset angle in these ranges, an inline two-cylinder engine equipped with such a crankshaft exhibits excellent vibration characteristics. This reduces the additional effort required to minimize the contributions of free inertial forces and free inertial moments. These free inertial forces and free inertial moments would otherwise be responsible for vibrations of the inline two-cylinder engine, which in turn would be transmitted to a support frame and thus perceived as disturbing vibrations by a rider sitting on the support frame.

[0010] A crankshaft offset angle of 135° is particularly preferred. At this angle, vibrations are minimal, resulting in very low-vibration operation of a parallel twin-cylinder engine equipped with this design. Simultaneously, the engine's sound is optimized, as it produces a sound nearly identical to that of a V-twin engine with a 90° cylinder angle. Thus, this crankshaft design allows for a parallel twin-cylinder engine that meets both high acoustic and comfort requirements.

[0011] In a preferred embodiment, the crankshaft has three journals. The journals serve to support the crankshaft in crankshaft bearings. The crankshaft bearings are advantageously plain bearings, in particular hydrodynamic plain bearings. In a particularly preferred embodiment of the invention, the crankshaft has exactly three journals.

[0012] Advantageously, the crankshaft has a central journal located between the first and second crankpins. In particular, the first and second crankpins are directly connected to the central journal. The central journal serves to support the crankshaft in the crankshaft bearing, which can be a plain bearing, especially a hydrodynamic plain bearing. Most preferably, the crankshaft has exactly one central journal, which simplifies the bearing arrangement.

[0013] It is also preferably provided that the crankshaft has two outer journals. One outer journal is located on the side of the second crankpin opposite the first, and the other outer journal is located on the side of the first crankpin opposite the second. Thus, the first and second crankpins, and especially the intermediate journal, are situated between the two outer journals. The outer journals allow the crankshaft to be supported in crankshaft bearings, which are plain bearings, particularly hydrodynamic plain bearings. It is particularly advantageous for the crankshaft to have exactly two outer journals, which simplifies the bearing arrangement.

[0014] The invention further relates to an inline two-cylinder engine having a crankshaft as described above. In particular, the inline two-cylinder engine is a gasoline engine. Such an inline two-cylinder engine has, on the one hand, an acoustically pleasing sound, and on the other hand, very low-vibration operation.

[0015] The inline two-cylinder engine preferably has a maximum of one balance shaft for damping vibrations. The balance shaft is connected to the crankshaft, particularly via a gearbox, allowing it to be driven by the crankshaft. The balance shaft preferably includes eccentrically arranged counterweights, so that the rotation of these counterweights dampens vibrations generated by the rotation of the crankshaft and the movement of the pistons driven by the crankshaft. This optimizes the vibration behavior of the inline two-cylinder engine. Since a maximum of one balance shaft is required, the inline two-cylinder engine is very simple and inexpensive to manufacture.

[0016] The inline two-cylinder engine is preferably a four-stroke engine, operating in particular according to the Otto cycle. It is provided that the inline two-cylinder engine has a first firing interval and a second firing interval. The first firing interval is, in particular, the interval between which a cylinder associated with the first crankpin and a cylinder associated with the second crankpin fire. The second firing interval is, in particular, the interval between which the cylinder associated with the second crankpin and the cylinder associated with the first crankpin fire. It is preferably provided that the first firing interval is advantageously less than 270°, in particular less than 260°, more preferably less than 250°, more preferably less than 240°, and more preferably less than 230°.It is also provided that the first firing interval is advantageously greater than 180°, in particular greater than 190°, preferably greater than 200°, and especially preferably greater than 210°, and particularly preferably greater than 220°. The second firing interval is advantageously less than 540°, in particular less than 530°, preferably less than 520°, and particularly preferably less than 510°, and particularly preferably less than 500°. Furthermore, it is provided that the second firing interval is advantageously greater than 450°, in particular greater than 460°, preferably greater than 470°, and particularly preferably greater than 480°, and particularly preferably greater than 490°. It is particularly advantageous that the first firing interval is 225° and the second firing interval is 495°. With such a firing interval, low-vibration operation of the inline two-cylinder engine is achieved, while simultaneously producing a visually appealing sound.In particular, by controlling injection timing and ignition timing using an electronic control system, fine adjustments can also be made during the operation of the inline two-cylinder engine, so that a balance can be struck between a comfortable running of the inline two-cylinder engine and an acoustically pleasing sound.

[0017] Finally, the invention relates to a motorcycle comprising a crankshaft, as previously described, and / or an inline two-cylinder engine, as previously described. Due to its low-vibration operation and the acoustically pleasing sound of the inline two-cylinder engine, it is ideally suited for use in a motorcycle. On the one hand, the reduced vibrations make connecting the motorcycle's frame to the inline two-cylinder engine very simple and cost-effective. At the same time, it offers the characteristic, appealing sound of a motorcycle. Thus, the motorcycle combines increased comfort with enhanced riding pleasure.

[0018] Further details, features and advantages of the invention will become apparent from the following description and the figures. These show:

[0019] Fig. 1 a schematic illustration of a crankshaft from the prior art,

[0020] Fig. 2 a schematic illustration of a crankshaft according to an embodiment of the invention,

[0021] Fig. 3 a schematic illustration of an inline two-cylinder engine according to an embodiment of the invention, and

[0022] Fig. 4 a schematic illustration of a motorcycle according to an embodiment of the invention.

[0023] Fig. Figure 1 schematically shows a crankshaft 1 according to the state of the art. The crankshaft 1 next to the first crankpin 2 and the second crankpin 3 a central shaft 4 on, which is between the first crankpin 2 and the second crankpin 3 is arranged. Furthermore, it is located on the opposite side of the first crankpin. 2 and the second crankpin 3 an external shaft 5 arranged. Thus, the crankshaft 1three bearing points, as there is one on each shaft journal 4 , 5 the crankshaft 1 It can be mounted on a crankshaft bearing. The crankshaft bearing is in particular a plain bearing, especially preferably a hydrodynamic plain bearing.

[0024] The in Fig. 1 shown crankshaft 1 is therefore suitable for use in an inline two-cylinder engine 10 (cf.) Fig. 3) trained. The first crankpin is 2 parallel to the second crankpin 3 aligned.

[0025] Fig. Figure 2 schematically shows a crankshaft 1 according to an embodiment of the invention. The crankshaft has 1 Basically the same structure as in Fig. 1 shown, on. Only the first crankpin is 2 to the second crankpin 3 offset. Thus, there is a gap between the first crankpin. 2 and the second crankpin 3an offset angle 100 present. The arrangement of the outer shaft journals remains unchanged. 5 and the central shaft pin 4 identical as in Fig. 1. Thus, this also applies to the crankshaft. 1 According to the embodiment of the invention, it is provided that three bearing points, in particular exactly three bearing points, are present, since the crankshaft 1 both on the outer shaft journals 5 as well as at the center shaft pivots 4 can be connected to a crankshaft bearing to secure the crankshaft 1 to be stored. The crankshaft 1 According to the embodiment of the invention, it is therefore also designed for use in an inline two-cylinder engine.

[0026] The offset angle 100is greater than 90°, advantageously greater than 100°, in particular greater than 110°, preferably greater than 120°, and most preferably greater than 130°. Likewise, the offset angle is less than 180°, advantageously less than 170°, in particular less than 160°, preferably less than 150°, and most preferably less than 140°. In the Fig. In the embodiment shown in 2, the offset angle has a value of 135°. Such a crankshaft 1 with the offset angle 100 between the first crankpin 2 and the second crankpin 3 is a straight two-cylinder engine 10 Can be manufactured with optimized vibration behavior. Such an inline two-cylinder engine 10 is in Fig. 3 shown. This shows next to the crankshaft 1 a first cylinder 11 as well as a second cylinder 12 up. In the first cylinder 11 is a first piston 6arranged, which is from the first crankpin 2 is driven, while in the second cylinder 12 one of the second crankpins 3 driven second piston 7 is arranged.

[0027] The inline two-cylinder engine 10 It is, in particular, a four-stroke engine, preferably operated using the Otto cycle. The inline two-cylinder engine features... 10 a first firing interval and a second firing interval. The first firing interval is the interval between the ignition of the first cylinder. 11 and an ignition of the second cylinder 12 The second firing interval is the interval between the ignition of the second cylinder. 12 and the ignition of the first cylinder 11 lies.

[0028] By using the crankshaft made of Fig. 2 is a first ignition interval less than 270°, in particular less than 260°, preferably less than 250°, particularly preferably less than 240°, particularly preferably less than 230° and greater than 180°, in particular greater than 190°, preferably greater than 200°, particularly preferably greater than 210°, particularly preferably greater than 220°. The second ignition interval is less than 540°, in particular less than 530°, preferably less than 520°, particularly preferably less than 510°, particularly preferably less than 500° and greater than 450°, in particular greater than 460°, preferably greater than 470°, particularly preferably greater than 480°, particularly preferably greater than 490°. In the Fig. In the embodiment shown in Figure 3, the first firing interval is 225°, while the second firing interval is 495°. This is achieved in particular by the offset angle. 100 the crankshaft 1 of 135° reached.

[0029] Such a firing interval results in an optimal acoustic sound from the parallel twin-cylinder engine. 10 given. At the same time, the offset angle is 100 a vibration of the inline two-cylinder engine of 135° 10 reduced. Therefore, the inline two-cylinder engine is suitable. 10 optimally suited for use in a motorcycle.

[0030] Fig. 4 shows a motorcycle 20 according to an embodiment of the invention. The motorcycle 20 features a support frame 9 as well as the one in Fig. 3 shown inline two-cylinder engine 10 on.

[0031] Through the crankshaft 1 A significant reduction in the proportions of free inertial forces and free inertial moments is achieved, thereby also reducing the forces and moments exerted by the inline two-cylinder engine. 10 on the support frame 9 of the motorcycle 20Transfers are minimized. This results in both the support frame 9 as well as the internal combustion engine 10 and also existing connection points for connecting the inline two-cylinder engine 10 to the support frame 9 They are very easy and inexpensive to manufacture and assemble. Due to the reduced vibration inherent in the inline two-cylinder engine. 10 in operation are the requirements for damping between support frames 9 and inline two-cylinder engine 10 reduced. This results in a very rigid connection for the inline two-cylinder engine. 10 to the support frame 9 enabled, which allows the inline two-cylinder engine 10 optimally a load-bearing element within the supporting frame 9 may be.

[0032] To optimize the vibration behavior of the inline two-cylinder engine 10 It is advantageous to have a maximum of one balance shaft.8 present. The balance shaft 8 is via a gearbox 13 with the crankshaft 1 connected, thereby the balance shaft 8 with the crankshaft 1 rotates. The balance shaft 8 features eccentrically arranged balancing masses (not shown) which are activated by the rotation of the balance shaft 8 generate counter-vibrations so that the vibrations caused by the crankshaft 1 as well as the pistons 6 , 7 can be generated, compensated for, or dampened.

[0033] While prior art requires at least two balance shafts to at least approximately compensate for the vibration behavior of an internal combustion engine, in particular an inline two-cylinder engine, the inline two-cylinder engine according to the invention requires no such compensation. 10 only one balance shaft at most 8provided for. Nevertheless, even in the inline two-cylinder engine according to the invention, vibrations are avoided or at least dampened to such an extent that they are not perceptible to a driver of a vehicle equipped with the inline two-cylinder engine. 10 equipped motorcycle 20 They are no longer perceived as disruptive. Therefore, the design and assembly effort of the inline two-cylinder engine is reduced. 10 reduced.

[0034] A crankshaft arrangement 1 , as in Fig. Figure 2 shows that this has significant disadvantages for the person skilled in the art, since vibrations occur in this area due to an uneven arrangement of the first crankpin. 2 and the second crankpin 3 at an offset angle 100 from 90° with tilting moments and swiveling moments superimposed at an offset angle 100 of 180° are formed. Thus, the offset angle according to the invention is formed 100Vibration angles greater than 90° and less than 180° were avoided in the prior art because large and therefore detrimental vibrations were expected. Surprisingly, however, it has been shown that the vibration behavior of the inline two-cylinder engine is significantly reduced precisely in this range. 10 occurs. Furthermore, such an offset angle leads to 100 to an acoustically pleasing sound from the parallel twin-cylinder engine 10 The inline two-cylinder engine according to the invention 10 as well as the crankshaft according to the invention 1 This resolves a long-standing conflict of objectives in the design of motorcycles between comfortable operation and acoustically pleasing sound. Reference symbol list 1 Crankshaft 2 First crankpin 3 Second crankpin 4 center shafts 5 external shaft journals 6 First piston 7 Second piston 8 Balance shaft 9 support frames 10 inline two-cylinder engine 11 First cylinder 12 Second cylinder 20 Motorcycle 100 offset angles

Claims

[1] Crankshaft ( 1 ) for an inline two-cylinder engine ( 10 ), comprising a first crankpin ( 2 ) and a second crankpin ( 3 ), wherein between the first crankpin ( 2 ) and the second crankpin ( 3 ) an offset angle ( 100 ) is present, which is greater than 90° and less than 180°. [2] Crankshaft ( 1 ) according to claim 1, characterized by that the offset angle ( 100 ) greater than 100°, in particular greater than 110°, preferably greater than 120°, particularly preferably greater than 130°, and / or less than 170°, in particular less than 160°, preferably less than 150°, particularly preferably less than 140°. [3] Crankshaft ( 1 ) according to any of the preceding claims, characterized by that the offset angle ( 100 ) 135°. [4] Crankshaft ( 1 ) according to one of the preceding claims, characterized by three shaft journals (4 , 5 ) for the bearing of the crankshaft ( 1 ) in crankshaft bearings. [5] Crankshaft ( 1 ) according to one of the preceding claims, characterized by a central shaft journal ( 4 ), which is between the first crankpin ( 2 ) and the second crankpin ( 3 ) is arranged and which provides a bearing for the crankshaft ( 1 ) in crankshaft bearings. [6] Crankshaft ( 1 ) according to one of the preceding claims, characterized by two external shaft journals ( 5 ), each with an outer shaft journal ( 5 ) on one of the first crankpins ( 2 ) opposite side of the second crankpin ( 3 ) and on one of the second crankpins ( 3 ) opposite side of the first crankpin ( 2 ) is arranged, and wherein the outer shaft journals ( 5 ) a crankshaft bearing ( 1) in crankshaft bearings. [7] Inline two-cylinder engine ( 10 ) comprising a crankshaft ( 1 ) according to any of the preceding claims. [8] Inline two-cylinder engine ( 10 ) according to claim 7, characterized by a maximum of one balance shaft ( 8 ) to balance rotating mass forces. [9] Inline two-cylinder engine ( 10 ) according to claim 7 or 8, characterized by that the inline two-cylinder engine ( 10) is a four-stroke engine, wherein a first firing interval is less than 270°, in particular less than 260°, preferably less than 250°, particularly preferably less than 240°, in particular particularly preferably less than 230°, and greater than 180°, in particular greater than 190°, preferably greater than 200°, in particular preferably greater than 210°, in particular particularly preferably greater than 220°, and a second firing interval is less than 540°, in particular less than 530°, preferably less than 520°, in particular particularly preferably less than 510°, in particular particularly preferably less than 500°, and greater than 450°, in particular greater than 460°, preferably greater than 470°, in particular preferably greater than 480°, in particular particularly preferably greater than 490°, and wherein the first firing interval is particularly advantageously 225° and the second firing interval is particularly advantageously 495°. [10] Motorcycle ( 20 ) comprising a crankshaft ( 1) according to one of claims 1 to 6 and / or an inline two-cylinder engine ( 10 ) according to one of claims 7 to 9.

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