DE102021121173A1 - Valve train for an internal combustion engine, internal combustion engine and motorcycle - Google Patents

Abstract

The invention relates to a valve drive (10) for an internal combustion engine, having at least two valve actuating elements (11, 12) and set up to actuate at least one valve actuating element (11, 12).

Description

The invention relates to valve trains for an internal combustion engine, set up to carry out an actuation of at least one valve actuation element. In addition, the invention relates to internal combustion engines having such a valve train and motorcycles having a valve train designed in this way and/or an internal combustion engine designed in this way.

In order to operate internal combustion engines efficiently, it is known to use valve trains in which both the valve lift and the valve opening duration can be adjusted. The purposeful use of changing valve lifts and valve control times should on the one hand use or set the engine’s speed-dependent power development and torque development and its idling behavior as effectively as possible, and on the other hand fuel consumption and exhaust emissions should be minimized. By means of a variable valve drive, for example, the intake timing can be changed, for example set to “late intake closing” in order to achieve stable idling behavior at reduced engine speeds and increased performance at high engine speeds, or set to “early intake closing” to increase engine performance at medium engine speeds to increase speeds.

Various concepts with camshaft controls that use different cam profiles, camshaft adjustments and/or cam follower adjustments have been developed as variable valve controls or valve drives. Furthermore, valve drives that can be actuated electromagnetically or electrohydraulically have been proposed. In the case of valve trains with two camshaft controls, better emission behavior can also be achieved by independently adjusting the exhaust camshaft.

Against this background, it is an object of the invention to improve a valve train for an internal combustion engine, an internal combustion engine and/or a motorcycle. In particular, a valve train for an internal combustion engine is to be improved in order to enable weight savings on the internal combustion engine.

This object is achieved by a valve train having the features of claim 1, an internal combustion engine having the features of claim 10 and a motorcycle having the features of claim 12. The dependent claims relate to developments of the invention.

According to a first aspect, a valve train for an internal combustion engine, in particular for a reciprocating piston engine of an internal combustion engine, is specified, having at least two valve actuating elements and set up to actuate at least one valve actuating element from a plane between the valve actuating elements. In particular, the valve drive is set up to actuate the at least two, in particular all, valve actuating elements, it being possible for the valve actuating elements to be actuated at the same time. A compact arrangement can be created by an actuation between the valve actuation elements, which leads to a saving in installation space and thus enables a weight reduction of the valve train or of the internal combustion engine.

In particular, the valve train for valve actuation is designed for a single-cylinder cylinder head. In this case, a cylinder opens out on one side in a crankshaft housing of an internal combustion engine and is closed or can be closed on the other side by at least one valve. This at least one valve can be actuated or opened and/or closed by means of a valve actuating element of the valve drive.

The valve train is set up to control valve control times and/or to generate a predetermined valve lift on the at least one associated valve in order to control a gas exchange in a cylinder. The gas exchange can take place, particularly in four-stroke engines, by at least one inlet valve and at least one outlet valve on a cylinder head, which seal off a combustion chamber of the cylinder and release fresh gas and exhaust gas separately.

The invention is based, among other things, on the idea of arranging an actuation plane, from which at least one valve actuation element of a valve train is actuated, in such a way that actuation can take place within a region that is described by components of the valve train. For this purpose it is provided that the actuation takes place in a plane between the valve actuation elements. This plane can have a surface normal that is parallel to an axis connecting the connecting elements, and/or the plane can have the same distance at each of its points from both connecting elements. By actuation in this plane, components required for actuation can be arranged in a space-saving manner. A cylinder and in particular a cylinder head in which the valve train can be arranged can therefore have a reduced volume, which makes it possible to save weight in the internal combustion engine.

In one embodiment, the actuation may occur on an axis between the valve actuation members that connects the valve actuation members together. As a result, the area of installation space occupied by the valve train can be used in an optimized manner; in particular, additional installation space for accommodating actuating components outside of the valve activation elements can be dispensed with, as a result of which a geometrically compact design of the valve train is made possible.

In one embodiment, the valve train has an actuating device, with the actuating device being arranged in a plane between the valve actuating elements. The actuating device is designed to actuate at least one of the valve actuating elements in order to effect a predetermined valve lift on a valve and/or to control a control time of the valve. By arranging the actuating device in one plane between the valve actuating elements, an optimized use of the installation space of the valve train can be made possible. In addition, actuation by the actuation device can take place in this plane, as a result of which a transmission path or deflection of an actuation movement can be shortened or even eliminated. Thus, components for actuation can be saved and the weight of the internal combustion engine can be reduced.

In one embodiment of the valve train, each valve actuating element is associated with a valve of an internal combustion engine. In particular, the valve actuating element is spatially assigned to the valve in such a way that the valve actuating element lies essentially in one plane with the valve. In addition, the valve actuating element can be arranged in a stroke direction of the associated valve in order to be able to bring about the most direct possible actuation of the valve. The valve actuating element can be set up to actuate a valve pneumatically, hydraulically, electromechanically or magnetically.

In some embodiments, the valve actuator is mechanically connected to a valve such that the valve is operable by the valve actuator to open and close the valve and/or control valve lift. For this purpose, a positive connection, in particular by means of a pickup, can be provided between the valve actuating element and the valve in order to transmit a movement, in particular an opening, a closing and/or a valve lift, to the valve or to effect it on the valve. For example, the valve can be opened by means of a pickup or cam follower in the form of a tappet, rocker arm or rocker arm. Closing of the valve can take place or at least be supported by means of a spring on the valve, in particular by means of a helical spring, torsion bar spring and/or gas spring, and/or via a desmodromic actuation.

In one embodiment, a cylinder of an internal combustion engine can have two intake valves and two exhaust valves, with each intake valve and/or each exhaust valve being assigned a valve actuating element of the valve train. In this case, the intake valves and the exhaust valves can each be arranged in one plane, with the intake valves and the exhaust valves being arranged opposite one another in relation to a central longitudinal axis of the cylinder. The information described herein regarding the spatial arrangement of the valves relates to a valve center axis of the respective valve, which essentially follows a stroke direction of the valve. The intake valves and/or the exhaust valves can be designed as valves arranged parallel to one another (in a row), in particular overhead valves, or the intake valves and/or exhaust valves hanging in the cylinder head can form an angle to one another (V-shaped valve arrangement). Compared to a cylinder head with valves hanging in parallel, this results in a more favorable shape of the combustion chamber and larger valve diameters can be used.

In one embodiment of the valve train, each valve actuation element is assigned to an intake valve. As a result, the control time of the intake valve can be adjusted by the valve actuation element in order to achieve the most efficient cylinder filling possible in all engine speed ranges. This allows an increase in the efficiency of the internal combustion engine and can have an effect as a gain in power and torque and as a fuel saving.

In one embodiment of the valve train, each valve actuation element is assigned to an outlet valve. As a result, the control time of the exhaust valve can be adjusted by the valve actuating element in order to bring about a greater "valve overlap", in which case, in particular, an exhaust valve and an intake valve can be open at the same time. The maximum power of the internal combustion engine at high speeds can be optimized by means of an extended valve overlap. Such an embodiment can also be used to optimize gas flows, for example exhaust gases can be drawn in again in a targeted manner.

In a further embodiment, the valve train is dependent on an internal combustion engine designed in such a way that each valve of the internal combustion engine is assigned a valve actuating element in order to improve the adaptability of control times of the valves of the internal combustion engine.

In one embodiment of the valve train, at least one valve actuation element is set up to provide at least two different actuation profiles for a valve. An actuation profile is characterized by a predetermined opening time and a predetermined closing time of a valve and, in particular, by a specific valve lift curve, which can be brought about by the valve actuating element on the valve. The valve drive is set up in particular to change or switch over from a first actuation profile to a second actuation profile for the valve by actuating the valve actuating element, in particular an actuation by means of the actuating device, and thus to change a control time or a valve lift on the valve.

In one embodiment, the at least one valve actuator includes a cam piece, the cam piece being configured to rotate about its own axis. A rotation can be a complete rotation, in particular a sequence of complete rotations, or a partial rotation, in particular within a predetermined angular range. The cam piece has at least one cam contour, with a size of the cam piece or a radial elevation of the cam piece controlling a travel or a valve lift of a valve and a sharpness of the cam piece or a cam profile controlling an opening time and a closing time in order to provide an actuation profile. In order to provide at least two actuation profiles, the cam piece can have at least two different cam contours, or the valve actuation element has at least two cam pieces, each with different cam contours. In this case, the different cam contours can be arranged adjacent to one another, in particular adjacent to one another.

By providing different actuation profiles, the efficiency of the internal combustion engine can be increased as a function of a speed, with a radially smaller cam contour being activated at idle or at a low speed of an internal combustion engine, and a radially larger cam contour being activated at full load.

In one embodiment of the valve train, at least one valve actuating element can be displaced axially by means of an actuating device. In particular, the valve actuation element can be displaced axially with respect to an axis which connects the valve actuation elements. The axis can be formed by a shaft, in particular a camshaft, on which the at least one valve actuating element can be arranged in a laterally displaceable manner. In this case, the, in particular all, valve actuating element/s can be designed as a cam piece with at least one cam contour.

The actuating device can be set up to move the valve actuating element axially from a first position, in which, for example, a first cam contour is activated or can be tapped, into a second position, in which the second cam contour is activated. For example, the actuating element can act laterally, in particular on a flank, of a valve actuating element in order to bring about an axial displacement. As a result, switching between two actuation profiles of the valve actuation element can be brought about, in order thus to enable the power of the internal combustion engine to be adjusted. Such an actuation of the valve actuation element in the form of an axial displacement enables an individualized activation of a predetermined control time and/or valve curve on a valve.

In one embodiment, the valve drive has a camshaft that can be displaced axially by means of an actuating device. The camshaft can be designed to rotate about its own axis, it being possible for the camshaft to be driven by the crankshaft, in particular at half the speed of the crankshaft. The at least two valve actuation elements can be arranged on the camshaft, and in particular each can be designed as at least one cam piece, in particular as described herein. The valve actuation elements are in particular arranged on the camshaft in such a way that they undergo a movement together with it, in particular a rotation and/or an axial displacement. As a result, several, in particular all, valve actuation elements can be actuated simultaneously. For example, the actuation device can act on the camshaft between the valve actuation elements in order to bring about an axial displacement. As a result, it is possible to save on actuation components of the valve train and to make actuation with a small space requirement possible.

In one embodiment of the valve drive, an actuating device has a cam switching element on a camshaft and the cam switching element is arranged, in particular in a rotationally fixed manner, between the valve actuating elements on the camshaft. The cam switching element can for example, have at least one helical groove in order to bring about an axial displacement of at least one valve actuating element and/or the camshaft. Actuation of the valve actuation element by means of the cam switching element can enable reliable actuation with a space-saving arrangement between the valve actuation elements.

In one embodiment of the valve drive, an actuating device has an actuator which is set up to actuate the cam switching element. In particular, the actuator can be designed to interact with the cam switching element in such a way that an axial displacement of at least one valve actuating element and/or the camshaft is brought about. In particular as a function of the speed and/or load of the internal combustion engine, the actuator can engage in the cam switching element and thus cause the at least one valve actuating element to be actuated. For this purpose, the actuator can engage, for example, in a spiral groove of a rotatable cam switching element and thus bring about an axial displacement of the camshaft and/or the valve actuating element from a first position into a second position.

In a further embodiment, the actuator can be set up to actuate a valve actuating element directly. The actuator can be reset mechanically via a throwback ramp, for example on the cam switching element or the valve actuating element. A shift can be completed after one revolution of the camshaft.

In one embodiment of the valve train, an actuating device is set up to be arranged inside a cylinder head cover of an internal combustion engine. The actuating device, in particular an actuator of the actuating device, can be arranged or fixed on a bearing bridge of a camshaft, on a cylinder head cover or on a cylinder wall. This compact arrangement of the actuating device allows a radial circumference of a cylinder head to be reduced, which makes it possible to save weight on the internal combustion engine.

According to a further aspect, an internal combustion engine is provided which has at least one valve train as described herein. The internal combustion engine can be designed as a single-cylinder engine, as a two-cylinder boxer engine, as a two-cylinder V engine or as a three-cylinder W engine.

In particular, a saving in installation space made possible by the valve train in the radial direction of the cylinder head cover makes it possible to have smaller dimensions for the cylinder head and thereby achieve a reduction in the weight of the internal combustion engine.

In a further embodiment of the internal combustion engine, an actuating device for the valve train is arranged within a cylinder head cover. In this case, the actuating device is arranged in particular in a plane between the valve actuating elements and can be arranged or fixed on a bearing bridge of a camshaft, on a cylinder head cover or a cylinder wall.

According to a further aspect, a motorcycle is specified, having at least one valve train described herein and/or at least one internal combustion engine described herein. Such a motor vehicle can enable efficient operation, in particular by saving weight.

• 1 zeigt einen Ventiltrieb gemäß einer beispielhaften Ausführung der vorliegenden Offenbarung einer Brennkraftmaschine in einer schematischen Ansicht.
• 2 zeigt den Ventiltrieb aus 1 gemäß der beispielhaften Ausführung der vorliegenden Offenbarung in einer weiteren schematischen Ansicht.
• 3 zeigt den Ventiltrieb aus 1 gemäß der beispielhaften Ausführung der vorliegenden Offenbarung in einer weiteren schematischen Ansicht.

Further advantages and application possibilities of the invention result from the following description in connection with the figures.

• 1 shows a valve train according to an exemplary embodiment of the present disclosure of an internal combustion engine in a schematic view.
• 2 shows the valve train 1 according to the exemplary embodiment of the present disclosure in another schematic view.
• 3 shows the valve train 1 according to the exemplary embodiment of the present disclosure in another schematic view.

1 shows a valve train 10 for an internal combustion engine according to a first embodiment in a plan view, the valve train 10 being set up to carry out an actuation of at least one valve actuating element 11, 12 from a plane E between the valve actuating elements 11, 12. The valve drive 10 has two valve actuating elements 11, 12 which are arranged on a first camshaft 13 in a rotationally fixed manner. The first camshaft 13 and a second exhaust-side camshaft 63 can be driven and rotated by means of a drive 60 .

An actuating device 14 has a cam switching element 15 which is arranged in a rotationally fixed manner on the camshaft 13, the cam switching element 15, which is designed as a switching worm, between the Valve operating elements 11, 12 is arranged. In addition, the actuating device 14 has an actuator 16 which is set up to actuate the cam switching element 15 . For this purpose, the actuator 16 has an actuator pin 26 , which can be actuated in particular electromagnetically, and which is set up to dip into a first spiral-shaped displacement groove 25 of a cam switching element 15 .

When the camshaft 13 rotates about its own axis 23, an axial displacement of the cam switching element 15 along the axis 23 can thus be brought about by interaction with the actuator 16. As a result, in a 1 illustrated first position activates a first cam contour 111, 121 of the valve actuation elements 11, 12 designed as cam pieces and thus a first actuation profile. A stroke movement with a predetermined valve control time and/or a predetermined valve lift can thus be brought about or transmitted to two associated intake valves 51, 52 of a cylinder 50.

Actuation of the cam switching element 15 by means of the actuator 16 at a second displacement groove 35 can result in an axial displacement of the valve actuating elements 11, 12 into a second position, here in the left direction in relation to the plane E. As a result, second cam contours 112, 122 and thus a second actuation profile can be activated in order to actuate the intake valves 51, 52 and to bring about a predetermined lift curve for them. Exhaust valves 53, 54 of the cylinder 50 can be actuated by means of the second camshaft 63 and cam pieces 61, 62 arranged thereon.

Through the proposed actuation of the valve actuation elements 11, 12 from a plane E between the valve actuation elements 11, 12, a compact arrangement of the valve train 10 can be created. In particular, an arrangement of the actuating device 14 in such a plane E enables an optimized use of installation space and a compact design of a cylinder head cover of an internal combustion engine that at least partially encloses the valve train. In addition, an ignition device 70 can be arranged at an angle, in particular in a plane between the inlet valves 51, 52 and the outlet valves 53, 54, in order to promote a space-saving design of the proposed valve train 10.

2 shows a sectional view AA of the valve train 10 1 . A cylinder 50 of an internal combustion engine, not shown in detail, has two inlet valves 51, 52 arranged parallel to one another, by means of which the cylinder 50 can be closed or closed. The valve drive 10 has two valve actuating elements 11, 12 which are arranged on a camshaft 13 of the valve drive 10 in a lifting direction of the valves 51, 52. The valve actuating elements 11, 12 are each connected to the valves 51, 52 by means of a pickup 511, 521 in order to adapt an actuating profile provided by a cam contour 111, 112, 121, 122 of the valve actuating element 11, 12, in particular in the form of a valve lift curve, to the respective Valve 51, 52 to be transferred.

The cam switching element 15 is arranged on the camshaft 13 between the two valve actuating elements 11 , 12 and can be actuated by means of an actuator 16 of an actuating device 14 . In the present exemplary embodiment, the actuator 16 of the actuating device 14 is arranged in the plane E, with the plane E describing a plane of symmetry of the inlet valves 51, 52. The cam switching element 15 can be displaced along the axis 23 of the camshaft 13 by means of the actuator 16, as a result of which the camshaft 13 or the valve actuating elements 11, 12 are actuated or axially displaced. The valve drive 10 is of compact design due to the arrangement, in particular in the middle, of the actuating device 14 between the valve actuating elements 11, 12. Arranging the ignition unit 70 at an angle to the plane E can promote this compactness.

3 FIG. 12 shows a view of the exemplary embodiment of a valve train 10. FIG 1 in a schematic representation. A drive 60 is set up to drive a first camshaft 13 and a second camshaft 63 . A rotation of the camshafts 13, 63 is converted into a lateral stroke movement on the valves 51, 52, 53, 54 by means of the cam pieces 11, 12, 61, 62 arranged in a rotationally fixed manner on the camshafts 13, 63. The cam pieces 11, 12 of the first camshaft 13 can be actuated by means of an actuating device 14 which is arranged in a plane between the cam pieces 11, 12. For this purpose, the actuating device 14 of this exemplary embodiment has a cam switching element 15 arranged in a rotationally fixed manner on the camshaft 13 and an actuator 16 for actuating this cam switching element 15 .

In a further exemplary embodiment, an actuating device 14 can be provided for the second camshaft 63 in order to enable actuation of switchable valve actuating elements on the second camshaft and thus to provide different actuating profiles for exhaust valves 53, 54 of the internal combustion engine.

An ignition device 70 of the internal combustion engine is between the drive 70 and the actuator transmission device 14, in particular at an angle, arranged.

Reference List

10

valve train

11, 12

valve actuator

13

camshaft

14

actuating device

15

cam switching element

16

actuator

23

axis

25, 35

shift groove

26

actuator pin

50

cylinder

51, 52

intake valve

53, 54

outlet valve

511, 521

customer

60

drive

61, 62

cam piece

63

second camshaft

70

ignition device

111, 121

first cam contour

112, 122

second cam contour

E

level

Claims (12)

Valve train (10) for an internal combustion engine, having at least two valve actuating elements (11, 12) and set up to carry out an actuation of at least one valve actuating element (11, 12) from a plane (E) between the valve actuating elements (11, 12). Valve train (10) after claim 1 , Having an actuating device (14), wherein the actuating device (14) is arranged in a plane (E) between the valve actuating elements (11, 12). Valve train (10) according to one of the preceding claims, wherein each valve actuating element (11, 12) is associated with a valve (51, 52, 53, 54) of an internal combustion engine. Valve train (10) according to one of the preceding claims, wherein at least one valve actuating element (11, 12) is set up to provide at least two different actuating profiles for a valve (51, 52, 53, 54). Valve drive (10) according to one of the preceding claims, wherein at least one valve actuating element (11, 12) can be displaced axially by means of an actuating device (14). Valve drive (10) according to one of the preceding claims, having a camshaft (13) which can be displaced axially by means of an actuating device (14). Valve drive (10) according to one of the preceding claims, wherein an actuating device (14) has a cam switching element (15) on a camshaft (13) and the cam switching element (15) is arranged between the valve actuating elements (11, 12) on the camshaft (13). . Valve train (10) after claim 7 wherein an actuating device (14) has an actuator (16) which is set up to actuate the cam switching element (15). Valve train (10) according to one of the preceding claims, wherein an actuating device (14) is set up to be arranged within a cylinder head cover of an internal combustion engine. Internal combustion engine, having at least one valve train (10) according to one of the preceding claims. internal combustion engine claim 10 , Having an actuating device (14) of the valve train (10) which is arranged within a cylinder head cover. Motorcycle, having at least one valve train (10) according to one of Claims 1 until 9 and/or at least one internal combustion engine claim 10 or 11 .

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