internal combustion engine for a motor vehicle as well as motor vehicle

Abstract

The invention relates to an internal combustion engine (4) for a motor vehicle, with at least one combustion chamber to which at least one gas exchange valve (2) is assigned, and with a variable valve train (1) by means of which the gas exchange valve (2), whose stroke can be varied by means of the variable valve train (1), can be actuated. The valve train (1) comprises a camshaft (3) rotatable about a camshaft axis of rotation (ND) with at least one cam (5).An intermediate device (7) is provided, which has a cam follower (8) that rests against an outer contour (6) of the cam (5) during each rotation of the camshaft (3) about the camshaft rotation axis (ND) and can be actuated via the cam follower (8) by means of the outer contour (6) of the cam (5) during each rotation of the camshaft (3) about the camshaft rotation axis (ND), whereby the gas exchange valve (2) can be actuated via the intermediate device (7) by means of the outer contour (6) of the cam (5).

Description

[0001] The invention relates to an internal combustion engine for a motor vehicle according to the preamble of claim 1. Furthermore, the invention relates to a motor vehicle with such an internal combustion engine.

[0002] EP 1 853 797 B1 discloses a variable mechanical valve control system for an internal combustion engine, comprising a rocker arm or rocker arm for adjusting the valve lift and the opening and closing time of at least one intake and / or exhaust valve. EP 1 807 609 B1 discloses a valve train for an internal combustion engine. DE 10 2015 111 056 A1 discloses a method for operating a four-stroke internal combustion engine. DE 10 2005 040 959 A1 discloses a variable-lift valve train. Furthermore, DE 10 2014 013 664 A1 discloses a valve train device for the independent, fully variable adjustment of the opening time of gas exchange valves in an internal combustion engine. DE 10 2011 121 641 A1 discloses a diesel engine. Furthermore, DE 101 40 635 A1 reveals a mechanically adjustable valve stroke adjustment.DE 11 2005 001 955 B4 discloses an internal combustion engine, and DE 10 2020 213 598 A1 discloses a drive system for a motor vehicle. DE 10 2019 133 590 A1 discloses a stroke actuator for a variable-stroke valve train with two working positions.

[0003] The object of the present invention is to create an internal combustion engine for a motor vehicle and a motor vehicle with such an internal combustion engine, so that excessive loads on the internal combustion engine can be avoided.

[0004] This problem is solved according to the invention by an internal combustion engine with the features of claim 1 and by a motor vehicle with the features of claim 7. Advantageous embodiments of the invention are the subject of the dependent claims.

[0005] A first aspect of the invention relates to an internal combustion engine, also referred to as a combustion engine or internal combustion power unit, and preferably designed as a reciprocating piston engine, i.e., a piston engine, for a motor vehicle, also simply referred to as a vehicle. This means that the motor vehicle, preferably designed as a motor vehicle, in particular as a passenger car, in its fully manufactured state, has the internal combustion engine and can be driven by means of the internal combustion engine. The internal combustion engine has at least one combustion chamber in which combustion processes take place during firing operation of the internal combustion engine. This occurs, in particular, such that within each operating cycle of the internal combustion engine, specifically, one of the combustion processes takes place.During the combustion process, a mixture, also known as a fuel-air mixture, is burned in the combustion chamber. This mixture comprises air, also referred to as combustion air or fresh air, and a fuel, preferably liquid or gaseous. The internal combustion engine is preferably a four-stroke engine. Particularly when the internal combustion engine is a reciprocating engine, the combustion chamber is partially bounded by a cylinder, partially by a combustion chamber roof, and partially by a piston that is movably mounted within the cylinder. The cylinder is formed by an engine block, also referred to as an engine housing, which may preferably be a crankcase, and in particular a cylinder crankcase.The combustion chamber roof is formed by another housing element of the internal combustion engine, with the engine block and the housing element being separate components yet connected to each other. For example, the housing element could be a cylinder head. The internal combustion engine has, for example, an output shaft, which could be a crankshaft. The output shaft is rotatable about an output shaft axis relative to the engine block. In particular, the output shaft is rotatably mounted to the engine block. For example, the piston is articulated to the output shaft via a connecting rod, so that translational movements of the piston within the cylinder and relative to the engine block can be converted into rotational movements of the output shaft about the output shaft axis and relative to the engine block.The combustion process drives the piston, which in turn drives the output shaft via the connecting rod, allowing it to rotate around the output shaft's axis of rotation relative to the engine block. In particular, when the internal combustion engine is a reciprocating piston engine, the output shaft is the aforementioned crankshaft. The respective working cycle of the internal combustion engine comprises, for example, a crankshaft angle of 720 degrees, and thus, specifically, two complete revolutions of the output shaft.

[0006] The combustion chamber is equipped with at least one gas exchange valve, which can be either an exhaust or an intake valve. The gas exchange valve is also simply referred to as a valve. Particularly when the gas exchange valve is designed as an intake valve, the combustion air mentioned above can be introduced into the combustion chamber via the gas exchange valve. The combustion process results in exhaust gas from the internal combustion engine. For example, if the gas exchange valve is designed as an exhaust valve, the exhaust gas can be discharged from the combustion chamber via the exhaust valve and, for example, introduced into the exhaust system of the internal combustion engine. The gas exchange valve is associated with a gas channel through which a gas can flow. For example, the gas channel runs within the housing element.In particular, if the gas exchange valve is an intake valve, the gas channel is an intake channel, such that the gas in question is the fresh air or at least includes the fresh air. Thus, the gas can be introduced into the combustion chamber via the gas channel. In particular, if the gas exchange valve is an exhaust valve, the gas channel is an exhaust channel through which the exhaust gas can flow, such that the gas includes the exhaust gas or that the exhaust gas can be discharged from the combustion chamber via the exhaust channel. For example, the gas exchange valve is movable, particularly relative to the housing element and preferably also relative to the engine block, between a closed position and several open positions, particularly translationally. The closed position is an end position of the gas exchange valve, which is moved to this end position but cannot be moved beyond it.The open position is a reversal position of the gas exchange valve, which, for example, moves from the closed position to the open position (or one of the open positions) within each operating cycle. In the open position, the valve reverses direction and then moves back to the closed position. Thus, within each operating cycle, the gas exchange valve moves to the open position but not beyond it. In the closed position, the gas channel is fluidly blocked by the gas exchange valve and therefore fluidly separated from the combustion chamber, preventing gas from flowing from the gas channel into the combustion chamber or vice versa.In its open position, the gas exchange valve releases the gas channel, allowing it to be fluidically connected to the combustion chamber and enabling gas to flow from the gas channel into the combustion chamber and vice versa. During each operating cycle, the gas exchange valve moves from the closed position to the open position by performing a stroke. In other words, the gas exchange valve completes its stroke as it moves from the closed position to the open position. Put another way, the gas exchange valve completes its stroke as it moves from the closed position to the open position, meaning that once the gas exchange valve has moved from the closed position to the open position, it has completed its stroke.

[0007] The internal combustion engine also features a variable valve train, which is also simply referred to as the valve train. The valve train actuates the gas exchange valve, whose stroke is variable via the valve train. By varying the stroke, the respective opening position of the gas exchange valve can be set. In other words, the feature that the stroke of the gas exchange valve is variable, i.e., adjustable, via the variable valve train means that by varying the stroke of the gas exchange valve, different stroke values, and in particular larger than zero, can be set, with each stroke value corresponding to, and in particular precisely, to, a specific opening position.In other words, if a first stroke value is set, and this first stroke value is greater than zero, then the gas exchange valve is moved, or can be moved, by means of the valve train, particularly within the respective operating cycle, from the closed position to, and in particular, a first of the open positions. If a second stroke value is set that is greater than the first stroke value, and in particular greater than zero, then the gas exchange valve is moved, or can be moved, by means of the valve train, particularly within the respective operating cycle, from the closed position to, and in particular, a second of the open positions, where the first open position lies between the second open position and the closed position.If, for example, a third stroke value is set, this leads to or results from the fact that, by means of the valve train, in particular within the respective working cycle, the gas exchange valve is moved or can be moved from the closed position to, in particular, exactly, a third of the open positions, wherein, for example, the third stroke value is greater than zero, greater than the first stroke value and greater than the second stroke value, so that the first open position is then between the closed position and the second open position and the second open position is between the first open position and the third open position and thus between the third open position and the closed position.Furthermore, the variable valve train is designed, for example, to set the stroke of the gas exchange valve to zero, i.e., to set a zero stroke of the gas exchange valve, whereby when the stroke of the gas exchange valve is set to zero, i.e., the zero stroke of the gas exchange valve is set, actuation of the gas exchange valve, i.e., movement of the gas exchange valve from the closed position to one of the open positions and thus opening of the gas exchange valve, is prevented, especially although the output shaft rotates around the output shaft axis relative to the engine block.

[0008] By actuating the gas exchange valve by means of the valve train, the gas exchange valve can be moved or is moved, particularly within the respective working cycle of the internal combustion engine, for example according to a valve lift curve.

[0009] The valve train has a camshaft that can rotate about a camshaft axis, particularly relative to the housing element and also relative to the engine block. For example, the output shaft axis and the camshaft axis run parallel to each other, or, for example, the camshaft axis and the output shaft axis are spaced apart from each other.

[0010] The camshaft has at least one cam by means of which the gas exchange valve can be actuated. The valve train also has an intermediate device which includes a cam follower. During each complete rotation of the camshaft about its axis of rotation, the cam follower rests against an outer contour of the cam, particularly directly, such that the cam follower remains in contact with the outer contour of the cam throughout the entire rotation of the camshaft about its axis of rotation. Thus, the cam follower follows the outer contour of the cam, particularly over the entire complete rotation of the camshaft.For example, the cam follower is a roller rotatably mounted on a base element of the intermediate device, such that, for example, during each rotation of the camshaft, the cam follower rolls along the outer contour of the cam, in particular directly, and thereby bears against the outer contour of the cam, and thus follows the outer contour, in particular directly. The intermediate device can be actuated via the cam follower by means of the outer contour of the cam during each rotation of the camshaft around its axis of rotation, thereby actuating the gas exchange valve via the intermediate device by means of the outer contour of the cam.In other words, during the respective rotation of the camshaft around the camshaft axis, the intermediate device can be actuated by means of the outer contour of the cam, whereby the gas exchange valve can be actuated by means of the intermediate device, so that the gas exchange valve can be actuated by means of the outer contour of the cam and thus moved from the closed position to the respective open position.

[0011] In order to avoid excessive stress on the internal combustion engine and thus excessive wear of the internal combustion engine, the invention provides that the outer contour of the cam has, in particular at least or exactly, an actuation area and, in particular at least or exactly, a first base circle area and, in particular, at least or exactly, a second base circle area. This means that during each complete rotation of the camshaft about the camshaft axis of rotation, the cam follower follows the actuation area, the first base circle area, and the second base circle area, and thus moves, in particular directly, along the actuation area, the first base circle area, and the second base circle area.

[0012] Within the actuation range, each rotation of the camshaft around its axis of rotation triggers the actuation of the intermediate device via the cam follower and the actuation of the gas exchange valve via the intermediate device. This means that when the cam follower follows the actuation range during each complete rotation of the camshaft, i.e., when it moves along the actuation range, the intermediate device is actuated via the cam follower and the gas exchange valve is actuated via the intermediate device. The valve train is thus designed so that, with each rotation of the camshaft, the actuation range actuates the intermediate device via the cam follower and the gas exchange valve via the intermediate device.In other words, the intermediate device can be actuated via the cam follower and the gas exchange valve via the intermediate device by means of the actuating range during each rotation of the camshaft. Put another way, during each rotation of the camshaft, the intermediate device can be actuated via the cam follower by means of the actuating range, resulting in the actuation of the gas exchange valve via the intermediate device.

[0013] In the first basic circle area, which, for example, directly adjoins the actuation area, neither the intermediate device nor the gas exchange valve is actuated during each rotation of the camshaft around its axis of rotation. This means that if, during each rotation of the camshaft, the cam follower follows the first basic circle area, i.e., if the cam follower moves along the first basic circle area, particularly directly, during each rotation of the camshaft, then neither the intermediate device nor the gas exchange valve is actuated.In other words, the valve train is designed so that in the first basic circle area, during each rotation of the camshaft, that is, when the cam follower moves, in particular directly, along the first basic circle area during each rotation of the camshaft, neither the intermediate device nor the gas exchange valve is actuated, thus preventing both actuation of the intermediate device and actuation of the gas exchange valve.

[0014] In the second basic circle area, which, for example, directly adjoins the first basic circle area, so that, for example, the first basic circle area is arranged between the actuation area and the second basic circle area, the intermediate device is actuated via the cam follower during each rotation of the camshaft around the camshaft axis of rotation, while in the second basic circle area, the gas exchange valve is not actuated during each rotation of the camshaft around the camshaft axis of rotation.This means that when the cam follower follows the second basic circle area during each rotation of the camshaft, i.e., when the cam follower moves along the second basic circle, particularly directly, during each rotation of the camshaft, the intermediate device is actuated or can be actuated via the cam follower, but despite this actuating of the intermediate device by means of the second basic circle area, the gas exchange valve is not actuated, so that the gas exchange valve remains in its closed position.In other words, the valve train is designed such that when the cam follower moves along the second base circle during each rotation of the camshaft, particularly when moving directly along the second base circle, the intermediate device is actuated, and thus moves relative to the gas exchange valve, but this does not result in the gas exchange valve being actuated. This has the following advantages: During each rotation of the camshaft, and thus particularly during the first part of the operating cycle of the internal combustion engine, the gas exchange valve can be actuated and thus opened by means of the actuating area.During the same rotation of the camshaft, and thus, for example, within a second part of the respective working cycle that directly follows the first part of the respective working cycle, actuation of the intermediate device and actuation of the gas exchange valve can be avoided by means of the first basic circle area, especially after the gas exchange valve has been actuated by means of the actuation area and has then returned to its closed position, so that the gas exchange valve can remain in its closed position during the second part.During the same rotation of the camshaft, and thus, for example, within a third part of the respective working cycle that directly follows the second part of the respective working cycle, the intermediate device can be actuated and thus moved by means of the second basic circle area, while the gas exchange valve is not actuated, i.e., while the gas exchange valve remains in its closed position.During the entire respective rotation of the camshaft, and thus, for example, during the entire respective working cycle of the internal combustion engine and / or during the first part, the second part, and the third part of the respective working cycle, the cam follower can be in direct contact with the outer contour of the cam and the gas exchange valve can be in direct contact with the intermediate device, so that the invention makes it possible to move the intermediate device by means of the second basic circle area, in particular relative to the gas exchange valve, while actuation of the gas exchange valve is omitted, while the cam follower is in direct contact with the outer contour of the cam and while the gas exchange valve is in contact with the intermediate device.If, for example, during the third part of the operating cycle an irregular combustion occurs, such as knocking in the combustion chamber, resulting in a particularly high and / or unfavorable force from the gas exchange valve acting on the intermediate device, then by allowing the intermediate device to be moved relative to the gas exchange valve by means of the second basic circuit area, without actuating the gas exchange valve, an unfavorable introduction of the force emanating from the gas exchange valve into the valve train, in particular the intermediate device, can be avoided.In other words, by using the second basic circuit area to actuate and thus move the intermediate device without opening the gas exchange valve, an advantageous introduction point can be set at which, or via which, the aforementioned force from the gas exchange valve can be introduced into the valve train, in particular the intermediate device. This prevents excessive stress on the valve train, resulting in particularly low-wear operation.

[0015] The invention is based in particular on the following findings and considerations: In order to achieve particularly fuel-efficient operation of internal combustion engines, modern internal combustion engines, for example those designed as spark-ignition engines, are designed to use variable valve trains and to set reduced valve lifts of the gas exchange valves, especially the intake valves, even under full load operation of the respective internal combustion engine, compared to the geometrically maximum possible lift. In particular, the internal combustion engines are also operated at high loads with reduced and thus very small valve lifts of the gas exchange valves, especially the intake valves, compared to the geometrically maximum possible lift, so that, for example, enrichment-free Miller cycle operation, i.e., enrichment-free operation using the so-called Miller cycle, is possible.It has been found that the very small valve lift at high loads, and especially at full load, can lead to significant stress, if not overload, on components of the valve train due to design constraints. This is particularly true when knocking occurs, i.e., when knocking combustion takes place and acts on the gas exchange valves, especially the intake valves. This can result from the fact that gas forces transmitted through the (especially elastically) closed gas exchange valves act on points in the valve train that are unfavorable with regard to stress on the valve train due to the small valve lift. Components of the valve train thus become significantly more sensitive to irregular combustion such as knocking. A design modification or adaptation of the valve train is very time-consuming and expensive, and not feasible due to the design.The aforementioned problems and disadvantages can be avoided by the invention. Since the valve train is designed as a variable valve train, the intermediate device can be designed or adjusted such that the second basic circle area, which is larger than the first basic circle area, does indeed lead to actuation and thus to a movement of the intermediate device, particularly relative to the gas exchange valve, but despite this actuation of the intermediate device, actuation of the gas exchange valve is prevented. In other words, the intermediate device counteracts or eliminates the actuation of the intermediate device that could be effected or is effected by means of the second basic circle area, and thus prevents actuation of the gas exchange valve, particularly when it is in the closed position, despite the actuation of the intermediate device that could be effected or is effected by means of the second basic circle area.This allows the actuation range to open the gas exchange valve with a very small stroke, enabling particularly fuel-efficient operation of the internal combustion engine. If the cam follower follows the second basic circle range and irregular combustion occurs, forces are advantageously transferred from the gas exchange valve to the intermediate device and the valve train at a specific point, because the second basic circle range actuates the intermediate device but does not actuate the gas exchange valve. This prevents excessive loads on the valve train.Since the outer contour of the cam has the first and second base circle regions, gas forces resulting from knocking combustion, and thus the resulting stress, act on areas of the valve train, thereby giving the valve train and its components advantageous robustness. A further advantage is that the valve train is not pre-stressed by a cam profile or the cam's outer contour in the area of ​​irregular combustion, such as knocking events, and different knocking and pre-ignition times can be accommodated.The first base circle area can remain unaffected by the use of the second base circle area and thus be designed like a conventional base circle of a conventional cam, so that, for example, the invention can be implemented without any influence on homologations and thus, for example, also in existing valve trains, in particular without negatively affecting the fuel consumption and emission behavior of the internal combustion engine.

[0016] Overall, it is evident that the intermediate device is designed to eliminate or control the actuation of the intermediate device caused or achievable by means of the second basic circuit area, so that despite this actuation of the intermediate device, the gas exchange valve is not actuated and thus, in particular, the gas exchange valve remains in its closed position.

[0017] To particularly advantageously avoid excessive stress on the valve train and to implement the invention particularly advantageously and simply, the invention provides that the actuation of the intermediate device, effected by means of the actuating area, comprises pivoting at least one part of the intermediate device, comprising at least the cam follower, about a pivot axis in a first pivoting direction. In particular, the pivot axis runs parallel to the camshaft axis of rotation and, more specifically, parallel to the output shaft axis of rotation, in particular such that the pivot axis is spaced apart from the camshaft axis of rotation and preferably also from the output shaft axis of rotation.It has proven advantageous if the actuation of the intermediate device, effected by means of the second basic circle, includes pivoting at least the part of the intermediate device encompassing the cam follower about the pivot axis in the first pivot direction. This allows the intermediate device to be moved particularly advantageously by means of the second basic circle in such a way that any forces resulting, for example, from knocking events, can be transferred from the gas exchange valve to the intermediate device at a particularly advantageous point. This prevents excessive loads on the intermediate device and thus on the valve train.

[0018] Another embodiment is characterized in that the actuation of the intermediate device, effected by means of the actuation area, includes pivoting at least part of the intermediate device about the pivot axis in the first pivot direction by a first angular amount. It is provided that the actuation of the intermediate device, effected by means of the second base circle area, includes pivoting at least part of the intermediate device about the pivot axis in the first pivot direction by a second angular amount that is smaller than the first. This means that the actuation area and the second base circle area pivot at least part of the intermediate device in the same pivot direction about the pivot axis; however, the actuation area pivots at least part of the intermediate device further or more sharply than the second base circle area.This allows the actuation of the intermediate device, which can be effected or brought about by means of the second basic circuit area, to be advantageously canceled, deleted, destroyed or controlled, so that despite this actuation of the intermediate device, the gas exchange valve is not actuated.

[0019] In the invention, the intermediate device comprises a first intermediate lever, which is pivotable about the pivot axis and has a raceway. The intermediate device also includes a second intermediate lever, for example, designed as a trailing lever, which has a follower element that rests against the raceway, in particular directly against it, and is movable, in particular rollable, along the raceway. This follower element is rotatably mounted, for example, on a base body of the second intermediate lever. The second intermediate lever can be actuated by pivoting the first intermediate lever about the pivot axis via the follower element, thereby actuating the gas exchange valve. The raceway has a section that lies on a circular arc whose center point is on the pivot axis.The characteristic that the track area lies on the aforementioned circular arc means that the track area, in particular, follows the imaginary circular arc precisely. When the intermediate device is actuated by means of the second basic circular area, the subsequent element moves only within the track area along the track. As a result, despite the pivoting of the first intermediate lever about the pivot axis when the intermediate device is actuated by means of the second basic circular area, the second intermediate lever is not actuated, and consequently, the gas exchange valve is not actuated.This means that although the second base circle section pivots the first intermediate lever about the pivot axis, the subsequent element only moves along the track section. Therefore, despite this pivoting of the first intermediate lever, the second intermediate lever is not actuated. Consequently, the gas exchange valve is not actuated and, in particular, remains in its closed position. This allows the stroke of the gas exchange valve to be varied particularly advantageously, and the intermediate device can advantageously cancel its actuation. Thus, despite the actuation of the intermediate device that could be effected or is effected by the second base circle section, the gas exchange valve is not actuated.

[0020] In a particularly advantageous embodiment of the invention, the valve train has an actuating element, for example designed as an eccentric cam, by means of which the intermediate device can be moved relative to the gas exchange valve and relative to the cam in order to vary the stroke of the gas exchange valve, which is also referred to as the valve stroke.

[0021] It has proven particularly advantageous if the intermediate device can be moved relative to the gas exchange valve into at least one position by means of the actuating element, in which, in the actuating range, during the respective rotation of the camshaft about the camshaft axis of rotation, the intermediate device is actuated via the cam follower and the gas exchange valve is actuated via the intermediate device; in the first basic circle range, during the respective rotation of the camshaft about the camshaft axis of rotation, neither the intermediate device nor the gas exchange valve is actuated; and in the second basic circle range, during the respective rotation of the camshaft about the camshaft axis of rotation, the intermediate device is actuated via the cam follower, but the gas exchange valve is not actuated.This allows excessive stress on the valve train to be avoided in a particularly simple and advantageous way.

[0022] It has proven particularly advantageous if at least one position of the intermediate device is a position of the first intermediate lever.

[0023] Finally, for achieving particularly low-wear operation, it has proven especially advantageous if the first base circle lies on an imaginary first circular arc segment, thus following an imaginary first circular arc segment, in particular directly or immediately, whose first center point lies on the camshaft axis of rotation. The second base circle lies on an imaginary second circular arc segment, whose second center point lies on the camshaft axis of rotation. The first circular arc segment has a first radius, and the second circular arc segment has a second radius that is larger than the first radius.This makes it possible to implement in a particularly advantageous way that in the first basic circuit area, the intermediate device and the gas exchange valve are not actuated, and that in the second basic circuit area, the intermediate device is actuated, but the gas exchange valve is not actuated.

[0024] A second aspect of the invention relates to a motor vehicle, also referred to simply as a vehicle, and preferably designed as a motor car, in particular as a passenger car, which has an internal combustion engine according to the first aspect of the invention and can be driven by means of the internal combustion engine. Advantages and advantageous embodiments of the first aspect of the invention are to be regarded as advantages and advantageous embodiments of the second aspect of the invention and vice versa.

[0025] Further details of the invention will become apparent from the following description of a preferred embodiment with the accompanying drawing. The drawing shows: Fig. 1. Partially a schematic perspective view of a valve train of an internal combustion engine for a motor vehicle; Fig. 2. Partially a schematic and perspective underside view of an intermediate lever of the valve train; Fig. 3 a schematic side view of a cam of the valve train; and Fig. 4 A diagram to illustrate the valve train.

[0026] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0027] Fig. Figure 1 shows a partial schematic side view of a valve train 1 of an internal combustion engine, also referred to as a reciprocating piston engine, i.e., a piston-driven engine, of a motor vehicle, which is also simply referred to as a vehicle and can be driven by means of the internal combustion engine. The internal combustion engine has at least one combustion chamber, not visible in the figures, to which at least one in Fig. 1 partially recognizable gas exchange valve 2 is assigned to it. In the embodiment shown in the figures, the gas exchange valve 2, designed as a poppet valve, is configured as an inlet valve. The valve train 1 is a variable valve train by means of which the gas exchange valve 2, whose stroke (also referred to as valve lift) can be varied by means of the variable valve train 1, can be actuated.

[0028] The valve train 1 has a camshaft 3 which is rotatable about a camshaft rotation axis ND, particularly relative to a housing element of the internal combustion engine (not shown in the figures). The internal combustion engine as a whole is designated by 4. Particularly well illustrated by Fig. 1 and Fig. 3 It is evident that the camshaft 3 has at least one cam 5 by means of which the gas exchange valve 2 can be actuated and thereby opened from a Fig. The closed position of the gas exchange valve 2 shown in Figure 1 can be moved into several open positions, different from the closed position and from each other, particularly translationally. For this purpose, the cam 5 has an outer contour 6, which will be explained in more detail below.

[0029] The valve train 1 also includes an intermediate device 7, which has a cam follower 8 that rests against the outer contour 6 of the cam 5, particularly directly, during each complete rotation of the camshaft 3 and thus of the cam 5 about the camshaft's axis of rotation ND. The cam follower 8 rests directly against the outer contour 6 and thus against the cam 5 during the entire complete rotation of the camshaft 3 and thus of the cam 5, and therefore follows the outer contour 6 during the entire rotation of the camshaft 3. As will be explained in more detail below, the cam follower 8 is a component of an intermediate lever 9 of the valve train 1, which is also referred to as the first intermediate lever. The intermediate lever 9 includes the cam follower 8 and a base element 10.In the embodiment shown in the figures, the cam follower 8 is a roller which is rotatably mounted on the base element 10 about a roller axis of rotation RD relative to the base element 10. The roller axis of rotation RD runs parallel to the camshaft axis of rotation ND and is spaced apart from the camshaft axis of rotation ND. Thus, the cam follower 8 rests against the outer contour 6 during the entire complete revolution of the camshaft 3 in such a way that, during each complete revolution of the camshaft 3, the cam follower 8 rolls directly along the outer contour 6 and thus moves along the outer contour 6. The valve train 1 includes a spring element 11, which is designed as a solid body and thus as a mechanical spring.By means of the spring element 11 a spring force can be provided or is provided by means of which the cam follower 8 is held or is held in, in particular direct, support with the outer contour 6, especially during the entire, respective, complete revolution of the camshaft 3.

[0030] During each complete rotation of the camshaft 3 around its axis of rotation ND, the intermediate device 7 can be actuated via the cam follower 8 by means of the outer contour 6 of the cam 5, thereby actuating the gas exchange valve 2 via the intermediate device 7 by means of the outer contour 6 of the cam 5. A second spring element 12, designed as a solid and thus as a mechanical spring, is associated with the gas exchange valve 2. When the gas exchange valve 2 is actuated, and thus during each movement of the gas exchange valve 2 from the closed position to the open position, the spring element 12 is tensioned, thereby providing a spring force by which the gas exchange valve 2 can be moved from the open position back to the closed position.

[0031] The gas exchange valve 2 is actuated, for example, and thus opened to allow air to enter the combustion chamber. This allows a mixture of air and fuel to be formed in the combustion chamber, which can then be combusted, in particular ignited and burned. The internal combustion engine 4 is specifically designed as a spark-ignition engine. After the air has been introduced into the combustion chamber, the gas exchange valve 2 is moved, in particular, back to its closed position and remains in this closed position, particularly while the mixture is burning in the combustion chamber. For example, if the mixture burns in the form of irregular combustion, such as knocking, gas forces can act on the gas exchange valve 2, which can result in, in particular, very high forces acting on the intermediate device 7 and thus on the valve train 1.

[0032] In order to avoid excessive stress on the valve train 1 and thus on the internal combustion engine 4, and therefore to achieve particularly low-wear operation of the internal combustion engine 4, the outer contour 6 of the cam 5 shows how particularly well Fig. As can be seen, in particular, an actuation range BB is defined, in which, during each rotation of the camshaft 3 about the camshaft axis ND, the intermediate device 7 is actuated via the cam follower 8 and the gas exchange valve 2 is actuated via the intermediate device 7. This means that when, during each complete rotation of the camshaft 3 about the camshaft axis ND, the cam follower 8 moves along the actuation range BB, both the intermediate device 7 and the gas exchange valve 2 are actuated, and thus the gas exchange valve 2 is moved from its closed position to one of its open positions, held in the open position, or moved back from the open position to the closed position.

[0033] The outer contour 6 of the cam 5 is in Fig. 3 illustrated by a solid line.

[0034] The outer contour 6 of the cam 5 also has, in this case, exactly two first basic circle areas GB1. Within each of these first basic circle areas GB1, the intermediate device 7 and the gas exchange valve 2 are not actuated during each rotation of the camshaft 3 about the camshaft axis ND. In particular, each basic circle area GB1 is directly adjacent to the actuation area BB. This means that when the cam follower 8 follows the respective basic circle area GB1 during each complete rotation of the camshaft 3 about the camshaft axis ND, i.e., when it moves within this first basic circle area GB1, neither the intermediate device 7 nor the gas exchange valve 2 are actuated.

[0035] Furthermore, the outer contour 6 of the cam 5 has exactly one second basic circle area GB2, in which, during each complete rotation of the camshaft 3 about the camshaft axis of rotation ND, the intermediate device 7 is actuated via the cam follower 8, but the gas exchange valve 2 is not actuated, thus remaining in the closed position. It can be seen that, viewed in the circumferential direction of the cam 5 and thus of the outer contour 6 around the camshaft axis of rotation ND, the respective basic circle area GB1 is arranged between the actuating area BB and the second basic circle area GB2.Between the respective first base circle area GB1 and the second base circle area GB2, a respective transition area UB of the outer contour 6 is arranged, wherein the outer contour 6 transitions from the respective base circle area GB1 to the base circle area GB2 and vice versa via the respective transition area UB. This means that when the cam follower 8 moves along the base circle area GB2 during the respective complete rotation of the camshaft 3 about the camshaft axis ND, thus following the base circle area GB2, the intermediate device 7 is actuated and thus moved at least partially relative to the gas exchange valve 2, but despite this actuation of the intermediate device 7, the gas exchange valve 2 is not actuated, and thus does not move from the closed position to one of the open positions.

[0036] In the embodiment shown in the figures, the respective first base circle region GB1 lies on a respective imaginary first circular arc segment, the respective first center point M1 of which lies on the camshaft axis of rotation ND. The second base circle region GB2 lies on an imaginary second circular arc segment, the second center point M2 of which lies on the camshaft axis of rotation ND and thus coincides with the first center point M1. The respective first circular arc segment has a respective first radius, with the first radii being equal. The first circular arc segments are thus arc segments of the same first circle, whose center point is the center point M1. The second circular arc segment has a second radius larger than the first radius. Thus, the second circular arc segment is a component of an imaginary second circle, whose center point coincides with and is the center point M2.In the respective transition region UB, the outer contour 6 extends, so to speak, from the respective base circle region GB1 or the respective first circular arc segment to the second base circle region GB2 or to the second circular arc segment, such that, while the respective base circle region GB1, GB2 is, in particular, strictly circular, the respective transition region UB is not necessarily circular or, in any case, is not part of an imaginary circle whose center lies on the camshaft rotation axis ND. In particular, the outer contour 6 in the respective transition region UB transitions continuously and / or seamlessly from the respective first base circle region GB1 to the second base circle region GB2, or vice versa.

[0037] Overall, it is evident that the intermediate device 7 is designed or configured to absorb, cancel, destroy, or control the actuation of the intermediate device 7 caused or effectable by means of the second basic circuit area GB2, so that despite this actuation of the intermediate device 7 caused or effectable by means of the basic circuit area GB1, a resulting actuation of the gas exchange valve 2 is prevented, i.e., avoided.

[0038] Recognizable from Fig. The intermediate device 7 comprises the intermediate lever 9 and a rocker arm 13 as a second intermediate lever. The intermediate lever 9 is pivotable about a first pivot axis S1, particularly relative to the aforementioned housing element and thus relative to, for example, a housing-fixed cam 15 of the valve train 1. The pivot axis S1 runs parallel to the camshaft rotation axis ND and parallel to the roller rotation axis RD and is spaced apart from both the camshaft rotation axis ND and the roller rotation axis RD. The intermediate lever 9 is part of the intermediate device 7, a part of which includes the cam follower 8.By means of the outer contour 6, the intermediate lever 9 can be actuated during each complete rotation of the camshaft 3 about the camshaft axis of rotation ND, and thus pivoted about the pivot axis S1 in a pivot direction relative to the housing element and therefore relative to the housing-fixed cam 15, as illustrated by an arrow 16. The characteristic that the cam 15 is housing-fixed means that the cam 15 is immovable relative to the housing element.

[0039] The rocker arm 13 is pivotable about a second pivot axis S2 relative to the housing element, in particular such that the rocker arm 13 can be actuated by actuating the intermediate lever 9, i.e., by pivoting the intermediate lever 9 about the pivot axis S2 and in the pivoting direction, and thus can be pivoted about the pivot axis S2. By pivoting the rocker arm 13 about the pivot axis S2, the gas exchange valve 2 can be actuated.

[0040] The second pivot axis S2 is spaced apart from the first pivot axis S1, as well as from the camshaft rotation axis ND and the roller rotation axis RD, and runs parallel to the pivot axis S1 and, in particular, also parallel to the camshaft rotation axis ND and parallel to the roller rotation axis RD. The rocker arm 13 has a follower element 17, which is designed as a second roller. Furthermore, the rocker arm 13 has a base body 18 on which the follower element 17 is rotatably mounted about a rotation axis DA relative to the base body 18. The intermediate lever 9, in particular the base element 10, has a raceway 22. The follower element 17 rests, in particular directly, against the raceway 22 and can move along the raceway 22.If the intermediate lever 9 is actuated by means of the outer contour 6 and thereby pivoted about the first pivot axis S1 and pivot direction relative to the housing element illustrated here by the arrow 16, the subsequent element 17 can move, in particular directly, along the raceway 22, in particular such that the subsequent element 17 rolls along the raceway 22, in particular directly, while rotating about the axis of rotation DA and relative to the base body 18.

[0041] The track 22 has a track section LB, which lies on an imaginary third circular arc, the third center point M3 of which lies on the pivot axis S1. When the intermediate lever 9 is actuated by means of the actuating area BB, the intermediate lever 9 is pivoted in the pivot direction illustrated by arrow 16 about the first pivot axis S1 by a first angular amount, which is such that the subsequent element 17 moves not only within the track section LB, but beyond the track section LB. Subsequently, the pivoting of the intermediate lever 9 pivots the trailing lever 13 about the second pivot axis S2, thereby actuating the gas exchange valve 2.However, if the intermediate lever 9 is actuated by means of the second base circle area GB2, the intermediate lever 9 is pivoted about the pivot axis S1 in the pivot direction illustrated by arrow 16 by a second angular amount smaller than the first, so that the follower element 17 moves along the raceway 22 only in the raceway area LB. This prevents actuation of the trailing lever 13, so that the trailing lever 13 is not pivoted despite the actuation of the intermediate lever 9 by means of the base circle area GB2. Consequently, the gas exchange valve 2 is not actuated, even though the intermediate lever 9 is actuated and thus pivoted by means of the second base circle area GB2.As a result, the intermediate device 7 is designed or configured to cancel, destroy, absorb, control or counteract the actuation of the intermediate lever 9 that can be effected or effected by means of the second basic circuit area GB2, so that despite this actuation of the intermediate lever 9, actuation of the rocker arm 13 and actuation of the gas exchange valve 2 do not occur.

[0042] The valve train 1 also includes an actuating element 19, which in this case is designed as an eccentric cam. The actuating element 19 is rotatable about an actuating axis BD, particularly relative to the housing element, i.e., pivotable, wherein the actuating element 19, i.e., its outer contour, is eccentric with respect to the actuating axis BD. By rotating the actuating element 19 about the actuating axis BD and relative to the housing element, the stroke of the gas exchange valve 2, also referred to as the valve lift, can be varied. This is because, for example, by rotating the actuating element 19 about the actuating axis BD and relative to the housing element, the position of the pivot axis S1, particularly relative to the pivot axis S2, can be adjusted, i.e., changed or varied.A third roller 20 is rotatably mounted on the intermediate lever 9 about the pivot axis S1 relative to the intermediate lever 9. This roller bears against a corresponding second raceway 21 of the cam 15, in particular directly, and can roll along the raceway 21, in particular directly. By rotating the actuating element 19 about the actuating axis BD and relative to the housing element, the roller 20 can be moved along the raceway 21 such that it rolls along the raceway 21. This allows the pivot axis S1 to be adjusted, i.e., moved, in particular relative to the pivot axis S2. Specifically, the roller 20 bears against the raceway 21 and against the actuating element 19, i.e., against its outer contour. The pivot axes S1 and S2 and the roller rotation axis RD, considered in pairs, are parallel to each other and spaced apart when considered in pairs.A first straight line, passing through the pivot axes S1 and S2, is perpendicular to a second straight line, passing through the roller rotation axis RD, with the second line intersecting the first line at a point located between the pivot axes S1 and S2. This allows the stroke of the gas exchange valve 2 to be varied advantageously and easily.

[0043] Fig. Figure 2 shows a section of the intermediate lever 9, in particular the base element 10, in a schematic and perspective bottom view. It looks especially good from Fig. 2. Career path 22 is recognizable.

[0044] Fig. Figure 4 shows a diagram with a first curve V1. The first curve V1 illustrates a movement of the intermediate lever 9, whose movement is effected or can be effected by the outer contour 6 of the cam 5 during each complete rotation of the camshaft 3 about the camshaft axis ND. A first part of the curve V1, illustrated by T1, shows a first part of the movement of the intermediate lever 9. During or through the first part of the movement of the intermediate lever 9, the intermediate lever 9 actuates the rocker arm 13, thereby actuating the gas exchange valve 2. A second part T2 of the curve V1 illustrates a second part of the movement of the intermediate lever 9. The second part of the movement of the intermediate lever 9 does not result in actuation of the rocker arm 13 and therefore does not result in actuation of the gas exchange valve 2.The first part of the movement of the intermediate lever 9 is effected or brought about by means of the actuation area BB, and the second part of the movement of the intermediate lever 9 is effected or brought about by the second basic circle area GB2. Third parts of the curve V1, located between parts T1 and T2 of the curve V1, illustrate that the intermediate lever 9 does not move, since the cam follower 8 moves along the respective first basic circle area GB1. In other words, the respective first basic circle area GB1 does not lead to a movement or actuation of the intermediate lever 9.

[0045] Recognizable from Fig. 4. Both the actuation area BB and the second base circle area GB2 pivot the intermediate lever 9 in the pivoting direction illustrated by arrow 16 about the first pivot axis S1. The actuation area BB pivots the intermediate lever 9 sufficiently to actuate the rocker arm 13, and consequently, the rocker arm 13 actuates the gas exchange valve 2. The base circle area GB2 pivots the intermediate lever 9 about the pivot axis S1 in the pivoting direction illustrated by arrow 16, but only so slightly that the follower element 17 moves only within the track area LB, i.e., only along the track area LB, but not beyond it. Therefore, actuation of the rocker arm 13 and, consequently, actuation of the gas exchange valve 2 are prevented.

[0046] A second V2 run in Fig. Figure 4 illustrates the forces acting on the gas exchange valve 2. A third part T3 of the curve V2 illustrates that, after the gas exchange valve 2 has returned to its standstill position and the cam follower 8 follows the second basic circle section GB2, an irregular combustion process, characterized in particular by knocking, takes place in the combustion chamber, resulting in particularly high forces acting on the gas exchange valve 2. These forces are now, since the basic circle section GB2 moves the intermediate lever 9 without actuating the gas exchange valve 2, in or on such advantageous, in Fig. The forces are introduced into the intermediate lever 9 at point P1, as described in Figure 2, in such a way as to avoid excessive loads on the intermediate lever 9 and thus on the valve train 1. If the outer contour 6 only had the actuation area BB and the first basic circle area GB1, and thus the second basic circle area GB2 and therefore the actuation of the intermediate lever 9 effected by the second basic circle area GB2 would be omitted, the aforementioned forces would be introduced into the intermediate lever 9 at or in a second point P2 of the intermediate lever 9, different from point P1. Due to a corresponding design of the intermediate lever 9, this would lead to an undesirably high load on the intermediate lever 9, which, however, can be avoided. This is evident from the following: Fig.2. In particular, points P1 and P2 are points, that is, parts of career path 22. Specifically, points P1 and P2 are points, positions, or areas of career path LB and thus of the third arc segment. Reference symbol list 1 Valve train 2 Gas exchange valve 3 camshaft 4 Internal combustion engine 5 cams 6 Outer contour 7 Intermediate facility 8 cam followers 9 intermediate levers 10 Basic Element 11 Spring element 12 spring element 13 rocker arms 15 Backdrop 16 Arrow 17 subsequent element 18 basic shapes 19 Actuating element 20 rolls 21 career 22 career ND camshaft rotation axis BD Actuating rotary axis S1 first pivot axis S2 second pivot axis DA axis of rotation LB Career Area P1 point P2 point BB area of ​​operation GB1 first basic circle area GB2 second basic circle area UB transition area M1 Center M2 center point M3 center point V1 progress V2 progress T1 Part T2 Part T3 Part

Claims

[1] Internal combustion engine (4) for a motor vehicle, comprising at least one combustion chamber to which at least one gas exchange valve (2) is assigned, and comprising a variable valve train (1) by means of which the gas exchange valve (2), the stroke of which can be varied by means of the variable valve train (1), can be actuated, wherein: - the valve train (1) has: ◯ a camshaft (3) rotatable about a camshaft rotation axis (ND) with at least one cam (5); and ◯ an intermediate device (7) which has a cam follower (8) which bears against an outer contour (6) of the cam (5) during each rotation of the camshaft (3) about the camshaft rotation axis (ND) and can be actuated via the cam follower (8) by means of the outer contour (6) of the cam (5) during each rotation of the camshaft (3) about the camshaft rotation axis (ND), whereby the gas exchange valve (2) can be actuated via the intermediate device (7) by means of the outer contour (6) of the cam (5), and - the outer contour (6) of the cam (5) has: ◯ an actuation range (BB) in which, during the respective rotation of the camshaft (3) about the camshaft rotation axis (ND), the intermediate device (7) is actuated via the cam follower (8) and the gas exchange valve (2) is actuated via the intermediate device (7), wherein the actuation of the intermediate device (7) effectable by means of the actuation range (BB) comprises pivoting about a pivot axis (S1) in a pivoting direction at least of a part of the intermediate device comprising at least the cam follower (8); and ◯ a first basic circle area (GB1) in which, during each rotation of the camshaft (3) about the camshaft rotation axis (ND), the intermediate device (7) and the gas exchange valve (2) are not actuated; and - the intermediate device (7) has: ◯ a first intermediate lever (9), which is part of the intermediate device (7) and is pivotable about the pivot axis (S1) and has a raceway (22); and ◯ a second intermediate lever (13) which has a follower element (17) that rests against the track (22) and is movable along the track (22), via which the second intermediate lever (13) can be actuated by pivoting the first intermediate lever (9) about the pivot axis (S1), thereby actuating the gas exchange valve (2); characterized by , that the outer contour (6) of the cam (5) has a second basic circle area (GB2) in which, during the respective rotation of the camshaft (3) about the camshaft rotation axis (ND), the intermediate device (7) is actuated via the cam follower (8) and the gas exchange valve (2) is not actuated, wherein: - the actuation of the intermediate device (7) by means of the second basic circle area (GB2) includes a pivoting about the pivot axis (S1) in the pivoting direction of at least the part of the intermediate device (7) comprising at least the cam follower (8); - the track (22) has a track section (LB) which lies on a circular arc whose center point (M3) lies on the pivot axis (S1); and - when the intermediate device (7) is actuated by means of the second basic circle area (GB2), the subsequent element (17) moves only in the track area (LB) along the track (22), whereby, despite the pivoting of the first intermediate lever (9) about the pivot axis (S1) when the intermediate device (7) is actuated by means of the second basic circle area (GB2), the second intermediate lever (13) is not actuated and the gas exchange valve (2) is not actuated. [2] Internal combustion engine (4) according to claim 1, characterized by , that: - the actuation of the intermediate device (7) effectable by means of the actuation area (BB) comprises the pivoting about the pivot axis (S1) in the pivoting direction of at least the part of the intermediate device (7) by a first angular amount; and - the actuation of the intermediate device (7) by means of the second basic circle area (GB2) includes the pivoting about the pivot axis (S1) in the pivoting direction of at least the part of the intermediate device (7) by a second angular amount which is smaller than the first angular amount. [3] Internal combustion engine (4) according to claim 1 or 2, characterized by , that the valve train (1) comprises an actuating element (19) by means of which the intermediate device (7) can be moved relative to the gas exchange valve (2) and relative to the cam (5) in order to vary the stroke of the gas exchange valve (2). [4] Internal combustion engine (4) according to claim 3, characterized by , that by means of the actuating element (19) the intermediate device (7) can be moved relative to the gas exchange valve (2) into at least one position in which: - in the actuation area (BB) during the respective rotation of the camshaft (3) about the camshaft rotation axis (ND), the actuation of the intermediate device (7) via the cam follower (8) and the actuation of the gas exchange valve (2) via the intermediate device (7) take place; - in the first basic circle area (GB1) during the respective rotation of the camshaft (3) about the camshaft rotation axis (ND), the intermediate device (7) and the gas exchange valve (2) are not actuated; and - in the second basic circle area (GB2) during the respective rotation of the camshaft (3) about the camshaft rotation axis (ND), the intermediate device (7) is actuated via the cam follower (8) and the gas exchange valve (2) is not actuated. [5] Internal combustion engine (4) according to claim 4, characterized by , that at least one position of the intermediate device (7) is a position of the first intermediate lever (9). [6] Internal combustion engine (4) according to any one of the preceding claims, characterized by , that: - the first basic circle area (GB1) lies on a first circular arc segment, the first center point (M1) of which lies on the camshaft rotation axis (ND); - the second base circle area (GB2) lies on a second circular arc segment, the second center point (M2) of which lies on the camshaft rotation axis (ND); - the first arc segment has a first radius; and - the second arc segment has a second radius that is larger than the first radius. [7] Motor vehicle, comprising an internal combustion engine (4) according to any of the preceding claims.

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