US20140224199A1

US20140224199A1 - Valve drive train device

Info

Publication number: US20140224199A1
Application number: US14/256,930
Authority: US
Inventors: Thomas Stolk; Alexander von Gaisberg-Helfenberg
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2011-10-21
Filing date: 2014-04-19
Publication date: 2014-08-14
Also published as: JP2014530978A; DE102011116653A1; WO2013056768A1; DE102011116653B4; CN103890327A; EP2769058A1

Abstract

In a valve drive train device for an internal combustion engine of a motor vehicle including at least one cam element which is mounted in a rotationally and axially displaceable manner and is provided for actuating at least one gas exchange valve, and at least one gate element which has at least one switch gate for valve lift switching, the switch gate being provided for converting a rotational movement of the cam element into an axial displacement movement of the cam element, a support element is connected to the cam element in a rotationally fixed manner and has at least one limiting structure for limiting the axial displacement movement of the cam element and the gate element is mounted in a rotationally fixed manner but is axially movable for the valve lift switching,

Description

This is a Continuation-In-Part application of pending international patent application PCT/EP2012/003778 filed Sep. 8, 2012 and claiming the priority of German patent application 10 2011 116 653.3 filed Oct. 21, 2011.

BACKGROUND OF THE INVENTION

The invention relates to a valve drive train device for an internal combustion engine of a motor vehicle.
A valve drive train device, in particular for an internal combustion engine of a motor vehicle, is already known from DE 10 2009 037 270 B4. It includes two cam elements which are each mounted on a camshaft in a rotationally and axially displaceable manner, and are each provided for actuating two gas exchange valves. Each cam element includes a gate element which has two switch gates for valve lift switching, the switch gates being provided for converting a rotational movement of the cam elements into an axial displacement movement of the cam elements. Each cam element further includes a support element which is connected to the cam element in a rotationally fixed manner and has a limiting element that is provided for limiting the axial displacement movement of the respective cam element.
The principal object of the invention is to provide a cost-effective valve drive train device with reliable operation.

SUMMARY OF THE INVENTION

In a valve drive train device for an internal combustion engine of a motor vehicle including at least one cam element which is mounted in a rotationally and axially displaceable manner and is provided for actuating at least one gas exchange valve, and at least one gate element which has at least one switch gate for valve lift switching, the switch gate being provided for converting a rotational movement of the cam element into an axial displacement movement of the cam element, a support element is connected to the cam element in a rotationally fixed manner and has at least one limiting structure for limiting the axial displacement movement of the cam element and the gate element is mounted in a rotationally fixed manner but is axially movable for the valve lift switching.
The design of the valve drive train device, in particular of the gate element and of the cam element, and also the mechanical limiting means of the axial displacement path of the cam element, can thus be structurally simplified, so that in particular manufacturing costs can be reduced. A simple and cost-effective valve drive train device may thus be provided. In addition, in a valve drive train device which has at least two cam elements, an independent axial displacement of the at least two cam elements can be achieved in a particularly simple manner, whereby the axial displacement may take place regardless of an instantaneous angular position.
The term “cam element that is mounted in a rotationally and axially displaceable manner” is understood in particular to mean a cam element that is mounted so as to be rotatable and axially displaceable with respect to a cylinder head or another stationary component of the internal combustion engine. A “gate element that is mounted in a rotationally fixed manner” is understood in particular to mean a gate element that is mounted so as to be rotationally fixed with respect to the cylinder head or the other stationary component of the internal combustion engine. The term “axial” is understood in particular to mean axial with respect to a main axis of rotation of the cam element. The term “valve lift switching” is understood in particular to mean a discrete switching between at least two valve actuating cams with curves which provide for a particular actuation of the at least one gas exchange valve. A “gate element” is understood in particular to mean a component which forms the switch gate and/or an element which forms the at least one switch gate, and which is situated on the component in a rotationally and axially fixed manner. A “switch gate” is understood to mean a unit having at least one gate track which is provided for converting a rotational movement into an axial displacement force, A “gate track” is understood in particular to mean a track for forced guiding of a gate engagement element at least on one side, preferably on both sides. The gate track is preferably designed in the form of a web, in the form of a slot, and/or in the form of a groove. A “gate engagement element” is understood in particular to mean an element which in at least one operating state engages at least partially with the switch gate and/or at least partially encloses the switch gate, and which is therefore preferably in operative connection with the switch gate, thus forcibly guiding the other way around the switch gate. The gate engagement element is preferably designed in the form of a shifting shoe which surrounds the web, in the form of a pin which engages in the slot, and/or in the form of a pin which extends into the groove. The term “connected in a rotationally fixed manner” is understood in particular to mean a connection which transmits a torque and/or a rotational motion unchanged. “Provided” is understood in particular to mean specially designed, equipped, and/or situated.
It is further proposed that the gate element is mounted in an axially displaceable manner for the valve lift switching. The valve lift switching may thus be achieved in a particularly simple manner. The gate element for the valve lift switching is preferably situated so as to be axially displaceable relative to the support element axial. A “gate element that is mounted so as to be axially displaceable” is understood in particular to mean a gate element that is mounted so as to be axially displaceable with respect to the cylinder head or the other stationary component of the internal combustion engine.
Furthermore, it is further proposed that the valve drive train device has at least one gate engagement element which is provided for an operative connection with the at least one switch gate, and which is situated so as to be movable at least essentially perpendicularly with respect to a main axis of rotation of the support element. Particularly advantageous valve lift switching may thus be achieved. An “operative connection” is understood in particular to mean a connection as the result of which the gate engagement element is forcibly guided by the switch gate, “Essentially” is understood in particular to mean a deviation that is no more than 15 degrees, advantageously no more than 5 degrees, and particularly advantageously no more than 2 degrees.
It is further proposed that the support element has at least one opening for providing the limiting element, and the gate engagement element at least partially passes through the at least one opening. Particularly simple limiting of the axial displacement path of the at least one cam element may thus be provided. An “opening” is understood in particular to mean a material void in the support element that is delimited by a material of the support element at least axially, and preferably in the circumferential direction.
In particular, it is advantageous when the at least one opening comprises two axial opening ends, and the gate engagement element for the limiting is provided so that it lies against the corresponding opening end, so that an additional element for limiting the axial displacement movement is not necessary. An “opening end” is understood in particular to mean an axial delimitation of the opening by the material of the support element. The two axial opening ends preferably define an opening width. The two axial opening ends advantageously define a maximum axial displacement path and thus a maximum axial displacement movement of the at least one cam element. “Lying against” is understood in particular to mean directly contacting.
Furthermore, it is advantageous when the gate engagement element is designed for continuously contacting the gate element in a spring-loaded manner, so that a secure operative connection between the gate engagement element and the switch gate may be achieved. “Spring-loaded” is understood in particular to mean that the valve drive train device has at least one spring element which acts on the gate element by means of an elastic force, the elastic force preferably pointing in the direction of the gate element and/or being oriented at least essentially perpendicularly with respect to the main axis of rotation.
It is also advantageous when the at least one cam element forms a guide for the gate engagement element, the guide being provided for at least partially accommodating the gate engagement element. The cam element may thus be axially displaced in a particularly advantageous manner. A “cam element which forms a guide for the gate engagement element” is understood in particular to mean a cam element whose material defines an area in which the gate engagement element is at least partially situated and may preferably move. In this context, “define” is understood in particular to mean surround and/or enclose.
In another embodiment according to the invention, the gate engagement element and the cam element are connected to one another in a rotationally fixed manner, as the result of which a particularly advantageous valve drive train device may be provided.
Furthermore, it is advantageous when the valve drive train device has at least one guide element which is provided for at least partially accommodating the at least one gate engagement element, and which is formed separately from the cam element and at least partially passes through the at least one opening. The service life of the gate engagement element may be prolonged in this way. A “guide element” is understood in particular to mean an element which is at least partially situated in the guide for the cam element, and which preferably at least partially directly surrounds and/or encloses the gate engagement element.
In addition, it is proposed that the valve drive train device has an actuator unit which is provided for displacing the gate element only axially for the valve lift switching. A complicated control, in particular of the at least one gate element, may thus be dispensed with, so that a cost-effective and simple control can be achieved. In addition, the actuator unit, which must be provided solely for displacing the gate element, may have a simple construction and thus, a cost-effective design.
In particular, it is advantageous when the gate engagement element is in the form of a switching pin and/or stop pin, whereby a particularly advantageous gate engagement element may be provided.
In addition, an internal combustion engine having a valve drive train device according to the invention is proposed, as the result of which manufacturing costs for the internal combustion engine may be reduced.
The invention will become more readily apparent from the following description of two exemplary embodiments with reference to the accompanying drawings. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art may also advantageously consider the features individually and combine them into further meaningful combinations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a valve drive train device for an internal combustion engine of a motor vehicle,

FIG. 2 shows an enlarged detail of the valve drive train device, and

FIG. 3 shows an enlarged detail of a valve drive train device having an alternative design.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIGS. 1 and 2 show a valve drive train device for an internal combustion engine of a motor vehicle, an enlarged detail of the valve drive train device being illustrated in FIG. 2. The valve drive train device is designed as a motor vehicle valve drive train device. The motor vehicle is designed as a passenger vehicle
The valve drive train device includes three cam elements 10 a, 11 a, 12 a, each of which has at least one cam 36 a for actuating a gas exchange valve. The cams 36 a in each case include two directly adjacent partial cams 37 a, 38 a which have different cam curvatures. The partial cams 37 a, 38 a may be designed, for example, for a full lift, a partial lift, or a zero lift. For simplicity, only the one cam 36 a is provided with a reference numeral in FIG. 1.
The cam elements 10 a, 11 a, 12 a are rotationally and axially displaceably mounted in a cylinder head of the internal combustion engine, not illustrated in greater detail. A cam follower, not illustrated in greater detail, may be displaced from one of the partial cams 37 a, 38 a to the other of the partial cams 37 a, 38 a by an axial displacement movement 18 a of the cam elements 10 a, 11 a, 12 a with respect to the gas exchange valves. Corresponding to a valve lift for which the appropriate partial cam 37 a, 38 a is provided, the corresponding gas exchange valve is then acted on with a full lift, a partial lift, or a zero lift. The cam elements 10 a, 11 a, 12 a have discrete switch positions that are associated with the individual partial cams 37 a, 38 a.
In principle, the cam elements 10 a, 11 a, 12 a may be provided for an inlet side or an outlet side. The internal combustion engine for which the illustrated valve drive train device is provided includes multiple gas exchange valves per cylinder in each case on the inlet side and/or on the outlet side. The illustrated cam elements 10 a, 11 a, 12 a are each provided for actuating two gas exchange valves which are associated with the same cylinder. The cams 36 a of the respective cam elements 10 a, 11 a, 12 a are each provided for the gas exchange valves of a single cylinder; i.e., in the installed state, each of the cam elements 10 a, 11 a, 12 a is associated with exactly one cylinder of the internal combustion engine and actuates the gas exchange valves situated on the inlet side or the outlet side of the cylinder. The number of cam elements 10 a, 11 a, 12 a thus corresponds to the number of cylinders of the internal combustion engine. The individual cam elements 10 a, 11 a, 12 a are connected to one another in a rotationally fixed but axially displaceable manner with respect to one another, and form a camshaft of the internal combustion engine.
The valve drive train device has a support element 19 a for supporting the cam elements 10 a, 11 a, 12 a, The cam elements 10 a, 11 a, 12 a and the support element 19 a are connected to one another in a rotationally fixed manner. The cam elements 10 a, 11 a, 12 a are supported on the support element 19 a in an axially displaceable manner, and are situated on the support element 19 a so as to be rotationally fixed but axially displaceable. The support element 19 a is situated inside the cam elements 10 a, 11 a, 12 a, and passes through the cam elements 10 a, 11 a, 12 a. The cam elements 10 a, 11 a, 12 a each have a hollow design and enclose the support element 19 a. The cam elements 10 a, 11 a, 12 a and the support element, 19 a are situated coaxially with respect to one another. The cam elements 10 a, 11 a, 12 a and the support element 19 a have a main axis of rotation 25 a about which they rotate during operation of the internal combustion engine. The support element 19 a is designed as a carrier shaft and has a hollow design. The support element 19 a has a tubular design.
In order to axially displace the cam elements 10 a, 11 a, 12 a, the valve drive train device includes a valve lift switching unit 39 a. The valve lift switching unit 39 a has a gate element 13 a which is mounted in a rotationally fixed manner. The gate element 13 a is mounted so as to be axially displaceable with respect to a valve lift switching relative to the support element 19 a The gate element is situated so as to be rotationally fixed but axially displaceable with respect to the valve lift switching relative to the support element 19 a. The gate element 13 a has three switch gates 14 a, 15 a, 16 a for the individual cam elements 10 a, 11 a, 12 a, respectively, for the valve lift switching, and thus for axially displacing the cam elements 10 a, 11 a, 12 a. The switch gates 14 a, 15 a, 16 a convert a rotational movement 17 a of the cam elements 10 a, 11 a, 12 a, respectively, into an axial displacement movement 18 a of the cam elements 10 a, 11 a, 12 a. For the valve lift switching, the gate element 13 a is mounted so as to be axially displaceable relative to the support element 19 a and the cam elements 10 a, 11 a, 12 a, but is rotationally fixed. The gate element 13 a is for the most part radially situated within the support element 19 a, and extends through the support element 19 a. The gate element 13 a is situated inside the cam elements 10 a, 11 a, 12 a. The support element 19 a and the cam elements 10 a, 11 a, 12 a rotate about the gate element 13 a during operation of the internal combustion engine, and enclose the gate element 13 a.
For limiting the axial displacement movement 18 a of the cam elements 10 a, 11 a, 12 a, the support element 19 a has three limiting elements, only two limiting elements 20 a, 21 a being visible on account of the angular position of the support element 19 a in FIG. 1. The limiting element which is not visible is concealed by the gate element 13 a. A limiting element 20 a, 21 a is associated in each case with a cam element 10 a, 11 a, 12 a; i.e., a limiting element 20 a, 21 a in each case limits the axial displacement movement 18 a of a respective corresponding cam element 10 a, 11 a, 12 a. The limiting element 20 a limits the axial displacement movement 18 a of the cam element 10 a, the limiting element 21 a limits the axial displacement movement 18 a of the cam element 11 a, and the limiting element which is not visible limits the axial displacement movement 18 a of the cam element 12 a.
The support element 19 a has openings 26 a, 27 a for providing the limiting elements 20 a, 21 a, respectively Each opening 26 a, 27 a provides a limiting element 20 a, 21 a, respectively. The openings 26 a, 27 a have two axial opening ends 28 a, 29 a and 30 a, 31 a, respectively, whose respective axial distance from one another limits a maximum displacement movement 18 a of the corresponding cam element 10 a, 11 a, 12 a. The axial distance between the opening ends 28 a, 29 a and 30 a, 31 a, respectively, corresponds to the width of the respective opening 26 a. 27 a. The opening ends 28 a, 29 a, 30 a, 31 a are in each case formed by a material of the support element 19 a. The openings 26 a, 27 a are formed by an absence of material of the support element 19 a, and are produced, for example, by drilling, milling, or the like. The openings 26 a, 27 a are situated at a distance from one another in an axial direction and in the circumferential direction. The openings are provided in the support element 19 a in an offset manner with respect to an axial direction and the circumferential direction.
In addition, the valve lift switching unit 39 a includes gate engagement elements 22 a, 23 a, 24 a which are provided for an operative connection with the switch gates 14 a, 15 a, 16 a, respectively, and which are connected to the cam elements 10 a, 11 a, 12 a, respectively. The gate engagement elements 22 a, 23 a, 24 a are connected to a cam element 10 a, 11 a, 12 a, respectively, in a rotationally fixed manner with respect to the main axis of rotation 25 a and are connected so as to be rotatable about the main axis of extension of the gate engagement elements 22 a, 23 a, 24 a perpendicular to the main axis of rotation 25 a The gate engagement element 22 a is associated with the cam element 10 a, the gate engagement element 23 a is associated with the cam element 11 a, and the gate engagement element 24 a is associated with the cam element 12 a, The gate engagement element 24 a is concealed by the gate element 13 a on account of an angular position of the cam element 12 a in FIG. 1, for which reason the gate engagement element 24 a is illustrated by a dashed line. The number of switch gates 14 a, 15 a, 16 a and the number of gate engagement elements 22 a, 23 a, 24 a are equal to the number of cam elements 10 a, 11 a, 12 a. Each of the cam elements 10 a, 11 a, 12 a has exactly one of the gate engagement elements 22 a, 23 a, 24 a. In turn, exactly one of the switch gates 14 a, 15 a, 16 a is associated with the gate engagement elements 22 a, 23 a, 24 a, respectively, and thus also with the cam elements 10 a, 11 a 12 a, respectively. In principle, a design having fewer or more than the three illustrated cam elements 10 a, 11 a, 12 a is conceivable, for example for an in-line engine having four, five, or six cylinders and a corresponding number of cam elements.
The switch gate 14 a and the gate engagement element 22 a which are in operative connection, the switch gate 15 a and the gate engagement element 23 a which are in operative connection, and the switch gate 16 a and the gate engagement element 24 a which are in operative connection are in each case provided for converting the rotational movement 17 a of the corresponding cam element 10 a, 11 a, 12 a about its main axis of rotation 25 a into the axial displacement movement 18 a along the main axis of rotation 25 a. The switch gates 14 a, 15 a, 16 a in each case include two gate tracks for displacing the cam elements 10 a, 11 a, 12 a, respectively. The first gate track is provided for displacing the cam element 10 a, 11 a, 12 a, which is associated with the corresponding switch gate 14 a, 15 a, 16 a, along a first switching direction from the first switch position into the second switch position. The second gate track is provided for displacing the cam element 10 a, 11 a, 12 a, which is associated with the corresponding switch gate 14 a, 15 a, 16 a, along a second switching direction from the second switch position into the first switch position. The switch gates 14 a, 15 a, 16 a each have the same number of gate tracks.
The gate tracks are axially inclined, at least in partial areas. When one of the gate engagement elements 22 a, 23 a, 24 a is meshed with the corresponding switch gate 14 a, 15 a, 16 a, a rotation of the cam element 10 a, 11 a, 12 a about the main axis of rotation 25 a causes a force to act on the cam element 10 a, 11 a, 12 a which results in displacement of the cam element 10 a, 11 a, 12 a along the main axis of rotation 25 a. The gate tracks in connection with the gate engagement elements 22 a, 23 a, 24 a convert a rotational movement of the cam elements into a linear movement. In areas in which the gate element 13 a has the switch gates 14 a, 15 a, 16 a, the gate element 13 a has an outer cylindrical lateral surface 40 a into which the switch gates 14 a, 15 a, 16 a are formed, The gate tracks thus face outwardly. The gate tracks are designed as grooves which are cut into the gate element 13 a. The gate element 13 a is situated in a rotationally fixed but axially displaceable manner with respect to the cylinder head.
The gate element 13 a forms the switch gates 14 a, 15 a, 16 a, and is designed as a switch gate carrier. The gate element 13 a is designed as a gate shaft The gate element 13 a, which forms the switch gates 14 a, 15 a, 16 a together with the gate tracks, is a one-piece design. The gate element 13 a forms the switch gates 14 a, 15 a, 16 a for all the coaxially situated cam elements 10 a, 11 a, 12 a. The gate element 13 a is a cast and/or forged part, and is formed from a single blank. The switch gates 14 a, 15 a, 16 a are subsequently introduced using a metal cutting process, in particular milling. In principle, the gate element 13 a may also be composed of a base shaft and a separate element which forms the switch gates 14 a, 15 a, 16 a and which is situated on the base shaft in a rotationally and displaceably fixed manner. Of course, it is also conceivable for each switch gate 14 a, 15 a, 16 a to be formed by a separate element, which in each case is situated on the base shaft in a rotationally and displaceably fixed manner.
For establishing the operative connection of the gate engagement elements 22 a, 23 a, 24 a with the respective switch gates 14 a, 15 a, 16 a, the gate engagement elements 22 a, 23 a, 24 a extend through a respective opening 26 a, 27 a. The gate engagement element 22 a extends through the opening 26 a, thus contacting the gate element 13 a. The gate engagement element 23 a extends through the opening 27 a, thus contacting the gate element 13 a. The gate engagement element 24 a extends through the opening which is not visible, thus contacting the gate element 13 a, The gate engagement elements 22 a, 23 a, 24 a are in each case situated between the corresponding opening ends 28 a, 29 a, 30 a, 31 a in the axial direction.
For limiting the axial displacement movement 18 a of the cam elements 10 a, 11 a, 12 a, the gate engagement elements 22 a, 23 a, 24 a, respectively, are provided for resting directly against the corresponding opening end 28 a, 29 a, 30 a, 31 a. To prevent the maximum displacement movement 18 a from being exceeded, the gate engagement elements 22 a, 23 a, 24 a strike against the corresponding opening end 28 a, 29 a, 30 a, 31 a, depending on the switching direction, which prevents a further axial displacement movement 18 a of the corresponding cam element 10 a, 11 a, 12 a into the switching direction and thus limits the axial displacement movement 18 a, The gate engagement elements 22 a, 23 a, 24 a are in the form of switch pins and stop pins which are guided on both sides in the gate tracks of the switch gates 14 a, 15 a, 16 a for valve lift switching and for limiting the axial displacement movement 18 a of the cam elements 10 a, 11 a, 12 a toward the corresponding opening end 28 a, 29 a, 30 a, 31 a and thus toward the support element 19 a.
The gate engagement; elements 22 a, 23 a, 24 a are situated on an inner periphery 41 a of the cam elements 10 a, 11 a, 12 a, respectively, and are each situated so as to be movable perpendicularly with respect to the main axis of rotation 25 a of the support element 19 a. The gate engagement elements 22 a, 23 a, 24 a are situated so as to he movable relative to the cam elements 10 a, 11 a, 12 a, respectively, and are movable, relative to the support element 19 a, perpendicularly with respect to the main axis of rotation 25 a of the support element 19 a. The gate engagement elements 22 a, 23 a, 24 a are connected in a rotationally fixed manner to cam elements 10 a, 11 a, 12 a, respectively, with respect to the main axis of rotation 25, and rotatably about the main axis of extension of the gate engagement elements 22 a, 23 a, 24 a perpendicular to the main axis of rotation 25, but may be displaced along their main extension, which extends in the radial direction with respect to the main axis of rotation 25 a. The gate engagement elements have one degree of freedom of motion in the corresponding cam element 10 a, 11 a, 12 a which is situated perpendicularly with respect to the main axis of rotation 25 a.
For accommodating the gate engagement elements 22 a, 23 a, 24 a, the cam elements 10 a, 11 a, 12 a, respectively, form a guide 32 a, 33 a for the corresponding gate engagement element 22 a, 23 a, 24 a. The guide for the gate engagement element 24 a formed by the cam element 12 a is not visible, since it is concealed by the support element 19 a and the gate element 13 a on account of the angular position of the cam element 12 a. The guides 32 a, 33 a are formed by a blind bore in the corresponding cam element 10 a, 11 a, 12 a. The guides 32 a, 33 a are in each case open toward the gate element 13 a, and are formed by a material of the corresponding cam element 10 a, 11 a, 12 a. For achieving the movable arrangement of the gate engagement elements 22 a, 23 a, 24 a and thus for providing the degree of freedom of motion of the gate engagement elements 22 a, 23 a, 24 a, the guides 32 a, 33 a in each case have a main extension that is oriented perpendicularly with respect to the main axis of rotation 25 a. The main extension of the gate engagement elements 22 a, 23 a, 24 a and the main extension of the guides 32 a, 33 a are radial. The material of the cam elements 10 a, 11 a, 12 a in each case directly surrounds the corresponding gate engagement element 22 a, 23 a, 24 a. When a gate engagement element 22 a, 23 a, 24 a rests against an opening end 28 a, 29 a, 30 a, 31 a, the gate engagement element 22 a, 23 a, 24 a transmits a force from the support element 19 a directly to the cam element 10 a, 11 a, 12 a, thus preventing further axial displacement movement 18 a. For limiting the axial displacement movement 18 a, the gate engagement elements 22 a, 23 a, 24 a are in each case provided for directly contacting the support element 19 a and the corresponding cam element 10 a, 11 a, 12 a. The axial displacement movement 18 a of the rotating cam element 10 a, 11 a, 12 a is limited by the rotating gate engagement element 22 a, 23 a, 24 a and the rotating support element 19 a.
To bring the gate engagement elements 22 a, 23 a, 24 a into engagement with the corresponding switch gate 14 a, 15 a, 15 a, the valve drive train device includes a plurality of actuating mechanisms 42 a, 43 a which are provided for automatically (i.e., without control by an actuator provided specifically for this purpose) bringing their associated gate engagement element 22 a, 23 a, respectively, into operative connection with the corresponding switch gate 14 a, 15 a. An actuating mechanism for the gate engagement element 24 a is not visible in the figures. The actuating mechanisms 42 a, 43 a are situated in the corresponding guide 32 a, 33 a for the corresponding cam element 10 a, 11 a, 12 a.
The gate engagement elements 22 a, 23 a, 24 a each are spring-loaded for continuously contacting the gate element 13 a. The actuating mechanisms 42 a, 43 a have a spring element 44 a, 45 a, respectively, which is supported on the associated cam element 10 a, 11 a and which exerts a force that is directed toward the respective gate engagement element 22 a, 23 a in the direction of the gate element 13 a. The spring elements 44 a, 45 a are situated in the corresponding guide 32 a, 33 a, respectively. One end of each spring element 44 a, 45 a rests against the corresponding cam element 10 a, 11 a, 12 a, and the other end of each spring element 44 a, 45 a rests against the corresponding gate engagement element 22 a, 23 a, 24 a. The elastic force is oriented parallel to the main extension of the guides 32 a, 33 a and parallel to the main extension of the gate engagement elements 22 e, 23 a, 24 a. The spring elements 44 a, 45 a press the gate engagement elements 22 a 23 a radially inwardly against the gate element 13 a. In principle, the gate engagement elements 22 a, 23 a, 24 a may be switchable, preferably by means of a control and regulation unit, in order, for example, to selectively axially displace only certain cam elements 10 a, 11 a, 12 a, for example to switch off at least one cylinder. Due to the switchable design of the gate engagement elements 22 a, 23 a, 24 a, the contacting of the gate element 13 a by the gate engagement elements 22 a, 23 a, 24 a may be selectively established. In the switchable design of the gate engagement elements 22 a, 23 a, 24 a, the gate element 13 a may also be mounted in an axially displaceably fixed manner, and thus in a rotationally and displaceably fixed manner.
The gate element 13 a is situated within the cam elements 13 a, 11 a, 12 a so as to be axially displaceable in order to selectively bring the gate engagement elements 22 a, 23 a, 24 a, respectively, into engagement with the corresponding gate track for the first switching direction or into engagement with the gate track for the second switching direction. For the valve lift switching, the valve lift switching unit 39 a has an actuator unit 35 a which only axially displaces the gate element 13 a for the valve lift switching. The actuator unit 35 a includes an individual control actuator 46 a which axially displaces the gate element 13 a for the valve lift switching. The gate element 13 a has two switch positions, which correspond to the switch positions of the cam elements 10 a, 11 a, 12 a.
The valve drive train device also has a drive wheel 47 a which drives the cam elements 10 a, 11 a, 12 a and the support element 19 a. The drive wheel 47 a provides a drive connection of the cam elements 10 a, 11 a, 12 a and the support element 19 a to a crankshaft of the internal combustion engine, not illustrated in greater detail. The drive wheel 47 a is designed as a crankshaft sprocket, and provides a drive connection of the cam elements 10 a, 11 a, 12 a and the support element 19 a to the crankshaft by means of a chain, not illustrated in greater detail. The drive wheel 47 a is a chain wheel. The support element 19 a and the cam element 10 a are connected to the drive wheel 47 a in a rotationally fixed manner. The drive wheel 47 a and the support element 19 a are formed together in one piece. In principle, the drive wheel 47 a may also be designed as a toothed belt wheel which provides a drive connection of the cam elements 10 a, 11 a, 12 a and the support element 19 a to the crankshaft by means of a toothed belt, not illustrated in greater detail. Of course, it is also conceivable for the cam elements 10 a, 11 a, 12 a to be in drive connection with the drive wheel 47 a solely via a rotationally fixed connection to the support element 19 a.
The valve drive train device has bearings 48 a, 49 a, 50 a, 51 a for supporting the drive wheel 47 a, the cam elements 10 a, 11 a, 12 a, and the support element 19 a. The bearings 48 a, 49 a, 50 a, 51 a support the drive wheel 47 a, the cam elements 10 a, 11 a, 12 a, and the support element 19 a on the cylinder head. The bearings are situated at an axial distance from one another.
If the gate element 13 a, starting from an operating state in which all cam elements 10 a, 11 a, 12 a of the valve drive train device are switched into the first switch position, is switched from its first switch position into the second switch position, the gate engagement elements 22 a, 23 a, 24 a of all cam elements 10 a, 11 a, 12 a are situated in axial overlap with a start of the respective gate tracks, which are provided for switching the cam elements 10 a, 11 a, 12 a from the first switch position into the second switch position. During a rotational movement 17 a of the cam elements 10 a, 11 a, 12 a, the gate engagement elements 22 a, 23 a, 24 a therefore engage with the corresponding gate track as soon as a rotational angle of the corresponding cam element 10 a, 11 a, 12 a has passed, i.e., when the start of the gate track in the radial direction is aligned with the gate engagement element 22 a, 23 a, 24 a.
After the valve lift switching, and thus after the corresponding displacement of the cam elements 10 a, 11 a, 12 a, the gate engagement elements 22 a, 23 a, 24 a of all cam elements 10 a, 11 a, 12 a, respectively, are situated in axial overlap with an end of the respective gate tracks, which are provided for switching the cam elements 10 a, 11 a, 12 a from the first switch position into the second switch position. As long as such an axial position of the gate element 13 a remains constant and therefore no axial displacement of the gate element 13 a takes place, the gate engagement elements 22 a, 23 a, 24 a of all cam elements 10 a, 11 a, 12 a are situated in axial overlap with the end of the respective gate track, thus preventing an axial displacement movement 18 a. If the gate element 13 a, starting from an operating state in which all cam elements 10 a, 11 a, 12 a of the valve drive train device are switched into the second switch position, is switched from its second switch position into the first switch position, the gate engagement elements 22 a, 23 a, 24 a of all cam elements 10 a, 11 a, 12 a are situated in axial overlap with a start of the respective gate track, which are provided for switching the cam elements 10 a, 11 a, 12 a from the second switch position into the first switch position, thus displacing the cam elements 10 a, 11 a, 12 a until the cam elements 10 a, 11 a, 12 a are situated in axial overlap with one end of the respective gate tracks, which are provided for switching the cam elements 10 a, 11 a, 12 a from the second switch position into the first switch position.
An angular range over which the particular cam element 10 a, 11 a, 12 a is displaced is defined by a phase position of the respective gate engagement element 22 a, 23 a, 24 a and a phase position of the associated switch gate 14 a, 15 a, 16 a, Since each cam element 10 a, 11 a, 12 a has one of the gate engagement elements 22 a, 23 a, 24 a and is associated with one of the switch gates 14 a, 15 a, 16 a, each of the cam elements 10 a, 11 a, 12 a may be displaced at a separate individual rotational angle. Each cam element 10 a, 11 a, 12 a thus has an individual angular sensitivity.
As soon as the gate element 13 a has been displaced by means of the control actuator 46 a, all cam elements 10 a, 11 a, 12 a, which are coupled to the gate element 13 a, are switched. The individual cam elements 10 a, 11 a, 12 a are automatically, independently displaced according to the switch position of the gate element 13 a as soon as the particular cam element 10 a, 11 a, 12 a has the corresponding rotational angle at which a displacement of the cam element 10 a, 11 a, 12 a is initiated.
FIG. 3 shows a second exemplary embodiment of the invention. The following description is limited essentially to the differences between the exemplary embodiments, wherein reference may be made to the description of the other exemplary embodiment, in particular in FIGS. 1 and 2, for components, features, and functions which remain the same. For distinguishing the exemplary embodiments, the letter “a” in the reference numerals for the exemplary embodiment in FIGS. 1 and 2 is replaced by the letter “b” in the reference numerals for the exemplary embodiment in FIG. 3. With regard to components denoted in the same way, in particular components having the same reference numerals, reference may basically also be made to the drawings and/or the description of the first exemplary embodiment, in particular in FIGS. 1 and 2.
FIG. 3 illustrates an enlarged detail of an alternative design of a valve drive train device for an internal combustion engine of a motor vehicle. In contrast to the preceding exemplary embodiment, the valve drive train device additionally has a guide element 34 b which accommodates a gate engagement element 22 b that is provided for the operative connection with a switch gate 14 b, The guide element 34 b is separate from a cam element 10 b, and partially passes through an opening 26 b, which provides a limiting element 20 b of an axial displacement movement. The guide element is partially situated within the cam element 10 b. The guide element 34 b is situated in a guide 32 b, and is inserted into the guide 32 b. The guide element 34 b is connected to the cam element 10 b in a rotationally fixed manner.
The guide element 34 b extends radially inwardly from the cam element 10 b and thus in the direction of a gate element 13 b. The guide element 34 b prevents the gate engagement element 22 b from directly striking an opening end 28 b and an opening end 29 b. For the limiting, the guide element 34 b rests against the corresponding opening end 28 b, 29 b of a support element 19 b. The guide element 34 b directly surrounds the gate engagement element 22 b and a spring element 44 b. The spring element 44 b at one end rests against the guide element 34 b, and at the other end rests against the gate engagement element 22 b. The spring element is supported on the cam element 10 b by means of the guide element 34 b. The cam element 10 b indirectly surrounds the gate engagement element 22 b. The guide element 34 b is situated between a material of the cam element 10 b and the gate engagement element 22 b, The guide element is provided for limiting the axial displacement movement and for directly contacting the support element 19 b and the cam element lob. The guide element prevents direct contact between the gate engagement element 22 b and the support element 19 b, as well as direct contact between the gate engagement element 22 b and the cam element 10 b. The guide element 34 b is designed as a guide sleeve. The gate engagement element 22 b is in the form of a switching pin.

LISTING OF REFERENCE NUMERALS

10 Cam element
11 Cam element
12 Cam element
13 Gate element
14 Switch gate
15 Switch gate
16 Switch gate
17 Rotational movement
18 Displacement movement
19 Support element
20 Limiting element
21 Limiting element
22 Gate engagement element
23 Gate engagement element
24 Gate engagement element
25 Main axis of rotation
26 Opening
27 Opening
28 Opening end
29 Opening end
30 Opening end
31 Opening end
32 Guide
33 Guide
34 Guide element
35 Actuator unit
36 Cam
37 Partial cam
38 Partial cam
39 Valve lift switching unit
40 Lateral surface
41 Inner periphery
42 Actuating mechanism
43 Actuating mechanism
44 Spring element
45 Spring element
46 Control actuator
47 Drive wheel
48 Bearing
49 Bearing
50 Bearing
51 Bearing

Claims

What is claimed is:

1. A valve drive train device for an internal combustion engine of a motor vehicle, comprising a camshaft with at least one cam element (10 a, 11 a, 12 a; 10 b) which is mounted in a rotationally and axially displaceable manner and is provided for actuating at least one gas exchange valve, and including a gate element (13 a; 13 b) which has at least one switch gate (14 a, 15 a, 16 a; 14 b) for valve lift switching, the switch gate being formed for converting a rotational movement (17 a) of the at least one cam element (10 a, 11 a, 12 a; 10 b) into an axial displacement movement (18 a) of the at least one cam element (10 a, 11 a, 12 a; 10 b), at least one support element (19 a 19 b) which is connected to the at least one cam element (10 a, 11 a, 12 a; 10 b) in a rotationally fixed manner and has at least one limiting structure (20 a, 21 a; 20 b) that is provided for limiting the axial displacement movement (18 a) of the at least one cam element (10 a, 11 a, 12 a; 10 b), the gate element (13 a; 13 b) being mounted in a rotationally fixed but axially movable manner for controlling the valve lift switching.

2. The valve drive train device according to claim 1, wherein at least one gate engagement element (22 a, 23 a, 24 a; 22 b) is provided for an operative connection with the at least one switch gate (14 a, 15 a, 16 a; 14 b), which gate engagement element is situated so as to be movable at least essentially perpendicularly with respect to a main axis of rotation (25 a) of the support element (19 a; 19 b).

3. The valve drive train device according to claim 2, wherein the support element (19 a; 19 b) has at least one opening (26 a, 27 a; 26 b) for forming the limiting structure (20 a, 21 a 20 b), and the gate engagement element (22 a, 23 a, 24 a; 22 b) at least partially passes through the at least one opening (26 a, 27 a; 26 b).

4. The valve drive train device according to claim 3, wherein the at least one opening (26 a, 27 a) has two axial opening ends (28 a, 29 a, 30 a, 31 a) and the gate engagement element (22 a, 23 a, 24 a) for limiting the axial displacement movement is provided to abut the respective opening end (28 a, 29 a, 30 a, 31 a)

5. The valve drive train device according to claim 2, wherein the gate engagement element (22 a, 23 a, 24 a; 22 b) is spring-biased so as to be in continuous contact with the gate element (13 a; 13 b).

6. The valve drive train device according to claim 2, wherein the at least one cam element (10 a, 11 a, 12 a; 10 b) forms a guide structure (32 a. 33 a; 32 b) for the gate engagement element (22 a, 23 a, 24 a; 22 b), the guide structure being provided for at least partially accommodating the gate engagement element (22 a, 23 a, 24 a; 22 b).

7. The valve drive train device according to claim 2, wherein the gate engagement element (22 a, 23 a, 24 a; 22 b) and the cam element (10 a, 11 a, 12 a; 10 b) are connected to one another in a rotationally fixed manner.

8. The valve drive train device according to claim 2, comprising at least one guide element (34 b) which is provided for at least partially accommodating the at least one gate engagement element (22 b), and which is formed separately from the cam element (10 b) and at least partially extends through the at least one opening (26 b).

9. The valve drive train device according to claim 1, comprising an actuator unit (35 a) which is provided for displacing the gate element (13 a; 13 b) only axially for the valve lift switching.