US20140318485A1

US20140318485A1 - Internal combustion engine valve drive adjustment device

Info

Publication number: US20140318485A1
Application number: US14/324,195
Authority: US
Inventors: Thomas Stolk; Alexander von Gaisberg-Helfenberg
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2012-02-21
Filing date: 2014-07-06
Publication date: 2014-10-30
Also published as: EP2817494A1; WO2013124020A1; JP2015507140A; EP2817494B1; DE102012003491A1; CN104136724A

Abstract

In a device for adjusting a valve drive of a motor vehicle internal combustion engine having at least one camshaft provided with first and second cam elements supported in an axially displaceable manner and each having cam tracks for actuating engine valves, the first cam elements have a number of cam tracks for actuating respective valves associated with the first cam elements and a different number of cam tracks for actuating valves associated with the second cam elements.

Description

This is a Continuation-In-Part application of pending international patent application PCT/EP2013/000023 filed Jan. 8, 2013 and claiming the priority of German patent application 10 2012 003 491.1 filed Feb. 21, 2012.

BACKGROUND OF THE INVENTION

The invention relates to a device for adjusting a motor vehicle valve drive having at least one camshaft with at least two cam elements which are axially displaceably supported on the at least one camshaft.
A device for adjusting a motor vehicle valve drive having a camshaft which includes at least two cam elements arranged in an axially displaceable manner, is known for example from DE 10 2007 037 747 A1.
It is the principal object of the present invention to provide a device for adjusting a variable motor vehicle valve drive train which is particularly variable and, at the same time, compact.

SUMMARY OF THE INVENTION

In a device for adjusting a valve drive of a motor vehicle internal combustion engine having at least one camshaft provided with first and second cam elements supported in an axially displaceable manner and each being having cam tracks for actuating engine valves, the first cam elements have a number of cam tracks for actuating respective valves associated with the first cam elements and a different number of cam tracks for actuating valves associated with the second cam elements.
Individual cam elements may thus be designed in a particularly variable manner and with more valve lifts than others, as a result of which the device for adjusting a motor vehicle valve train may have a particularly variable design. It is also possible for example that an additional cam track is a no-lift cam track provided for example for half of the cam elements, which permits an operational shutdown of half of the cylinders for a more economical operation of the engine when not all the cylinders are needed.
A “camshaft” is understood in particular to mean a shaft that is provided for activating multiple valves of a motor vehicle internal combustion engine and for activating a valve of at least one cam track in each case. It is also conceivable for the camshaft to be designed as an intake camshaft and provided for activating intake valves, or it is also possible for the camshaft to be designed as an exhaust camshaft for activating exhaust valves. A “cam element” is understood in particular to mean an element which is mounted on a camshaft in a rotationally fixed manner, and which, for operating a valve, is provided for directly or indirectly acting on the valve in question with at least one lift. The term “in a rotationally fixed manner” is understood in particular to mean a connection that transmits a torque and/or a rotational motion unchanged. The term “axial” is understood in particular to mean axial in relation to a main axis of rotation of the cam element. The term “axially displaceable” is understood in particular to mean that the cam element is displaceable on the camshaft, parallel to the main axis of rotation of the cam element, between at least two working positions. A “cam track” is understood in particular to mean an area of the cam element, extending on the periphery of the cam element, which forms a valve activation curve for activating a valve and/or which defines the valve activation. The term “at least two cam elements” is understood in particular to mean that the device for adjusting a motor vehicle valve train includes at least two cam elements, or also, depending on the number of cylinders in the motor vehicle internal combustion engine, includes three cam elements, four cam elements, five cam elements, six cam elements, eight cam elements, or some other number of cam elements that appears meaningful to one skilled in the art.
It is further proposed that the cam elements arranged in an axially displaceable manner in each case have at least two cam tracks per valve for adjusting a valve lift of at least one valve of a cylinder. The device for adjusting a motor vehicle valve train may thus have a particularly advantageous design. A “valve lift” is understood in particular to mean a movement of the valve which is triggered by the cam tracks of the cam elements, in which the valve preferably lifts from its valve seat and thus opens up a flow cross section. The term “adjusting a valve lift” is understood in particular to mean a switchover between two cam tracks which define an activation of the at least one valve.
It is further proposed that at least one of the cam elements has at least one cam track providing for a valve lift, and a cam track providing for a zero lift.
A particularly advantageous cylinder switching-off function may thus be provided. A “zero lift” is understood in particular to mean that a valve which is activated with zero lift and which over a complete revolution of the cam element has a constant valve lift preferably remains in its valve seat, and a flow cross section of the valve thus remains blocked over the entire period of time in which the zero lift track is engaged. In the process, over a complete revolution of the cam element in question the cam track having a zero lift preferably remains free of contact with the corresponding valve and does not contact it. The valve in question remains inactivated while a cam element having a zero lift is engaged.
It is further proposed that another of the cam elements exclusively has at least one cam track with a valve lift. The cam element in question may thus have a particularly advantageous and compact design, as the result of which the overall device for adjusting a motor vehicle valve train may be compact.
It is further proposed that one of the at least two cam elements has two cam tracks for activating a particular valve and another of the at least two cam elements has three cam tracks for activating a particular valve. The device for adjusting a motor vehicle valve train may thus have a particularly variable design.
It is further proposed that the camshaft includes four axially displaceable cam elements with two cam elements in each case having two cam tracks for activating a valve, and the other two cam elements in each case having three cam tracks for activating a valve. A particularly advantageous device for adjusting a motor vehicle valve train for a four-cylinder internal combustion engine in a motor vehicle may be provided in this way.
It is further proposed that the cam element, which has three cam tracks in each case, has a zero lift track. The cylinder switching-off function may thus be integrated into the device for adjusting a motor vehicle valve train particularly well and in a simple manner.
It is further proposed that the device for adjusting a motor vehicle valve train has a control unit which is provided for switching the at least two cam elements, at least in part, independently of one another. The cam elements may thus be switched in a particularly advantageous manner, and the device for adjusting a motor vehicle valve train may have a particularly variable design. A “control unit” is understood in particular to mean a unit having at least one control device. A “control device” is understood in particular to mean a unit having a processor unit and a memory unit, and having an operating program stored in the memory unit. In principle, the control unit may have multiple interconnected control devices which are preferably provided for communicating with one another via a bus system, in particular a CAN bus system. The term “provided” is understood in particular to mean specially programmed, designed, and/or equipped. The term “switch, at least in part, independently of one another” is understood in particular to mean that a cam element may be switched in an operating state, regardless of whether the other cam elements are switched. For switching the cam elements, this may involve the same actuator, which may switch the cam elements individually and independently of one another. Switching of all cam elements over a period of less than 10 camshaft revolutions is understood in particular to mean dependent switching of the cam elements which is not independent in the sense of separately switchable cam elements.
It is further proposed that the control unit is provided for changing a switching position of at least one of the cam elements and to maintain a switching position of at least one other cam element, in at least one operating state. A cam element may thus be switched independently of the other cam element in a particularly advantageous manner. A “switching position of a cam element” is understood in particular to mean a defined position of the cam element which the cam element assumes after completion of a switching operation, and in which a defined cam track is engaged with the valve in question. The term “change a switching position” is understood in particular to mean that a cam element is switched from one switching position into another switching position. The term “maintain a switching position” is understood in particular to mean that the switching position of the cam element remains the same, and in particular there is no switching into another switching position.
It is further proposed that in at least one operating state at least one of the cam elements is engaged with a cam track which triggers a different valve lift than another of the cam elements. The motor vehicle internal combustion engine may thus be operated in a particularly variable manner.
The invention will become more readily apparent from the following description of a particular embodiment with reference to the accompanying drawings. The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will also advantageously consider the features individually and combine them into further meaningful combinations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic illustration of a device according to the invention for adjusting a motor vehicle valve drive; and

FIG. 2 shows a characteristic map of the device according to the invention for adjusting a motor vehicle valve drive, the characteristic map being divided into various operating ranges.

DESCRIPTION OF A PARTICULAR EMBODIMENT OF THE INVENTION

FIG. 1 shows a device according to the invention for adjusting a motor vehicle valve train. The device for adjusting a motor vehicle valve drive is part of a motor vehicle internal combustion engine 51, not illustrated in detail. The motor vehicle internal combustion engine 51 is part of a motor vehicle, and has four cylinders. In principle, it is also conceivable for the motor vehicle internal combustion engine 51 to have a different number of cylinders that appears meaningful to one skilled in the art. For each cylinder, the motor vehicle internal combustion engine 51 has for example two valves in the form of intake valves, and two valves in the form of exhaust valves. In principle, it is also conceivable for the motor vehicle internal combustion engine 61 to have only one intake valve and one exhaust valve for each cylinder, or some other number of intake and/or exhaust valves that appears meaningful to one skilled in the art. The device for adjusting a motor vehicle valve train has a camshaft 10 in the form of an intake camshaft, which is provided for activating the valves intake valves, and a camshaft 10, not illustrated in greater detail, which is an exhaust camshaft and which is provided for activating the exhaust valves. For reasons of clarity, only the camshaft 10 which is an intake camshaft is described below. In principle, an exhaust camshaft may have essentially the same design as the camshaft 10 described below which is an intake camshaft. The intake camshaft 10 and the exhaust camshaft may act with different lifts on the valves which they activate; the lifts may differ in their maximum lift as well as in a lift characteristic. The camshaft 10 is rotatable supported in a cylinder head of the motor vehicle internal combustion engine 51.
The camshaft 10 includes four cam elements 11, 12, 13, 14 arranged in an axially displaceable manner. The first cam element 11 is associated with a first cylinder and the corresponding valves. The second cam element 12 is associated with a second cylinder and the corresponding valves. The third cam element 13 is associated with a third cylinder and the corresponding valves. The fourth cam element 14 is associated with a fourth cylinder and the corresponding valves. The axially displaceable cam elements 11, 12, 13, 14 are provided for activating and adjusting a valve lift of two valves of a cylinder in each case. The cam elements 11, 12, 13, 14 are connected in a rotationally fixed manner to the camshaft 10 via a positive fit, not illustrated in greater detail. The cam elements 11, 12, 13, 14 are displaceable in an axial direction which extends parallel to a main axis of rotation 36 of the camshaft 10, in principle, it is also conceivable for the cam elements 11, 12, 13, 14 to be connected to the camshaft 10 in some other way that appears meaningful to one skilled in the art.
The number of cam tracks 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 for activating a valve of one of the cam elements 11, 12, 13, 14 and the number of cam tracks 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 for activating a valve of another of the cam elements 11, 12, 13, 14 are different from one another. The first cam element 11, which is arranged in an axially displaceable manner, and the fourth axially displaceable cam element 14 for adjusting a valve lift of a valve of a cylinder in each case have two cam tracks 15, 16, 17, 18, 27, 28, 29, 30 per valve. The first cam element 11 and the fourth element 14 in each case have two first cam tracks 15, 17, 27, 29 and two second cam tracks 16, 18, 28, 30. Each first cam track 15, 17, 27, 29 and each second cam track 16, 18, 28, 30 are associated with the same valve of a cylinder, and have different valve lifts and lift characteristics. The first cam tracks 15, 17, 27, 29 and the second cam tracks 16, 18, 28, 30, which in each case are associated with the same valve of the particular cylinder, are adjacently situated in each case on the corresponding cam element 11, 14. The first cam tracks 15, 17, 27, 29 of the cam elements 11, 14 are provided for a small valve lift. The second cam tracks 16, 18, 28, 30 of the cam elements 11, 14 are provided for a large valve lift. The first cam tracks 15, 17, 27, 29, which are provided for a small valve lift, have a smaller maximum distance from the main axis of rotation 36 of the camshaft 10 than the second cam tracks 16, 18, 28, 30, which are provided for a large lift. The cam elements 11, 14 in each case have a different cross section in an area of the first cam tracks 15, 17, 27, 29 than in an area of the second cam tracks 16, 18, 28, 30.
The second cam element 12 and the third cam element 13 in each case have three cam tracks 19, 20, 21, 22, 23, 24, 25, 26, 31, 32, 33, 34 per valve for adjusting a valve lift of a valve of the associated cylinder. The second cam element 12 and the third cam element 13 in each case have two first cam tracks 19, 21, 23, 25, two second cam tracks 20, 22, 24, 26, and two third cam tracks 31, 32, 33, 34. Each first cam track 19, 21, 23, 25, each second cam track 20, 22, 24, 26, and each third cam track 31, 32, 33, 34 are in each case associated with the same valve of a cylinder, and have different valve lifts and lift characteristics. All three cam tracks 19, 20, 21, 22, 23, 24, 25, 26, 31, 32, 33, 34 are adjacently situated, and in each case adjoin one another directly. The first cam tracks 19, 21, 23, 25 in each case are situated between the third cam tracks 31, 32, 33, 34 and the second cam tracks 20, 22, 24, 26. The first cam tracks 19, 21, 23, 25 of the second cam element 12 and of the third cam element 13 have the same design as the first cam tracks 15, 17, 27, 29 of the first cam element 11 and of the fourth cam element 14, and are provided for a small valve lift. The second cam tracks 20, 22, 24, 26 of the second and third cam elements 12, 13, respectively, have the same design as the second cam tracks 16, 18, 28, 30 of the first and fourth cam elements 11, 14, respectively, and are provided for a large valve lift. The third cam tracks 31, 32, 33, 34 of the second cam element 12 and of the third cam element 13 have a zero lift. The third cam tracks 31, 32, 33, 34 of the second and third cam elements 12, 13, respectively, do not cause activation of the valve over a complete revolution of the cam elements 12, 13. The third cam tracks 31, 32, 33, 34 have a maximum distance from the main axis of rotation 36 of the camshaft 10 that is smaller than that of the first cam tracks 19, 21, 23, 25. The third cam tracks 31, 32, 33, 34 have no contact with the associated valve during a complete revolution of the cam element 12, 13. The third cam tracks 31, 32, 33, 34 of the cam elements 12, 13 do not activate the valves, as the result of which the corresponding cylinder is not charged with a fuel-air mixture, and therefore cannot be ignited. While the third cam tracks 31, 32, 33, 34 of a cam element 12, 13 are engaged, the corresponding cylinder is switched off and generates no drive torque. In principle, it is also conceivable for the third cam tracks 31, 32, 33, 34 to contact the valve, but not to lift the valve from its valve seat.
Other designs of the cam elements 11, 12, 13, 14 are also conceivable in principle. Thus, for example, it is conceivable that only one cam element 11, 12, 13, 14 has a different number of cam tracks 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 than the remaining cam elements 11, 12, 13, 14 of the camshaft 10. In principle, however, it is also conceivable that another number of cam elements 11, 12, 13, 14, which appears meaningful to one skilled in the art, may have a different number of cam tracks 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34. In principle, it is also conceivable for at least one cam element 11, 12, 13, 14 to have only one cam track 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, or a different number of cam tracks 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 which appears meaningful to one skilled in the art, that is greater than three. In principle, it is also conceivable for at least one of the cam elements 11, 12, 13, 14 to have at least two cam tracks 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 in each case for activating a valve in each case, and for another of the at least two cam elements 11, 12, 13, 14 to have at least three cam tracks 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 in each case for activating a valve in each case, whereby none of the cam tracks 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 has a zero lift.
For adjusting the cam elements 11, 12, 13, 14, the device for adjusting a motor vehicle valve train includes an actuator device 37, which for adjusting the valve lift is provided for axially displacing the cam elements of the camshaft 10. The cam tracks 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, which are engaged with the particular valve, are changed by axial displacement of the cam elements 11, 12, 13, 14. The first cam element 11 and the second cam element 12 each have a first switching position and a second switching position. The second cam element 12 and the third cam element 13 have a first switching position, a second switching position, and a third switching position. In the first switching position of one of the cam elements 11, 12, 13, 14, in each case the two first cam tracks 15, 17, 19, 21, 23, 25, 27, 29 of the cam element are engaged, and activate the corresponding valve of the corresponding cylinder. The valves of the cylinders having the small valve lift are activated in the first switching position. In the second switching position of one of the cam elements 11, 12, 13, 14, in each case the two second cam tracks 16, 18, 20, 22, 24, 26, 28, 30 of the cam element 11, 12, 13, 14 are engaged and activate the corresponding valve of the corresponding cylinder. The valves of the cylinders having the large valve lift are activated in the second switching position. The third cam tracks 31, 32, 33, 34 of the second cam element 12 and of the third cam element 13 are engaged in each case in the third switching position. Since the third cam tracks 31, 32, 33, 34 in each case have zero lift and the respective valves remain inactivated, the corresponding cylinders are switched off in a third switching position of the second and third cam elements 12, 13, respectively.
The device for adjusting a motor vehicle valve train includes a control unit 35. The control unit 35 is part of an engine control system. In principle, it is also conceivable for the control unit 35 to be designed as a separate unit. The control unit 35 is provided for switching the at least four cam elements 11, 12, 13, 14 independently of one another. For switching a cam element 11, 12, 13, 14 from one switching position into the other switching position, the control unit 35 transmits an electrical or electronic signal to the actuator device 37, which then switches over the corresponding cam element 11, 12, 13, 14 from one switching position into the other switching position. The control unit 35 is provided to change the switching position of one of the cam elements 11, 12, 13, 14 and to maintain the switching position of another cam element 11, 12, 13, 14, in at least one operating state. As a result, the control unit 35 changes the valve lift of the one cam element 11, 12, 13, 14 from a small to a large valve lift, from a large to a small valve lift, or from one of the valve lifts to a zero lift, whereby the valve lift of the other cam element 11, 12, 13, 14 which is not switched over maintains its previous small valve lift, large valve lift, or zero lift. It is conceivable for the control unit 35 to switch only one cam element 11, 12, 13, 14, two cam elements 11, 12, 13, 14, three cam elements 11, 12, 13, 14, or all four cam elements 11, 12, 13, 14 at least essentially at the same time, in a defined operating state. The actuator device 37 may result in temporal differences, which preferably amount to only up to two camshaft revolutions.
At least one of the four cam elements 11, 12, 13, 14 in at least one operating state is engaged with a cam track 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 which triggers a different valve lift than a cam track 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 that is engaged with another of the four cam elements 11, 12, 13, 14. Various cam elements 11, 12, 13, 14 in an operating state are engaged with cam tracks 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 which for the corresponding valves trigger various valve lifts or zero lift. Thus, for example, in one operating state at least one of the four cam elements 11, 14 is in the first switching position, and thus is engaged with a cam track 15, 17, 27, 29 which triggers a small valve lift, while at least one other of the four cam elements 12, 13 is in the third switching position, i.e., is engaged with the third cam track 31, 32, 33, 34 which triggers a zero lift.
The actuator device 37 includes a central actuator 38 which is provided for switching all four cam elements. In principle, it is also conceivable for the actuator device 37 to include two actuators 38, each of which is provided for switching two of the four cam elements 11, 12, 13, 14. In principle, it is also conceivable that for switching each of the cam elements 11, 12, 13, 14, the actuator device 37 has a separate actuator which in each case switches only one cam element 11, 12, 13, 14 that is associated with it. In principle, any other configuration and/or number of actuators that appears meaningful to one skilled in the art is conceivable in order to switch the cam elements 11, 12, 13, 14. In addition, actuators that switch only one cam element 11, 12, 13, 14 and actuators that switch multiple cam elements 11, 12, 13, 14 may be combined.
As illustrated in FIG. 2, the device for adjusting a motor vehicle valve train has four different operating ranges 39, 40, 41, 42. The speed of the motor vehicle internal combustion engine 51 is plotted on the abscissa 52, and the power of the motor vehicle internal combustion engine 51 is plotted on the ordinate 53 in the diagram in FIG. 2. In principle, it is also conceivable for the device for adjusting a motor vehicle valve train to have some other number of operating ranges 39, 40, 41 42 that appears meaningful to one skilled in the art. The various operating ranges 39, 40, 41, 42 are associated with a power-speed range of the motor vehicle internal combustion engine 51. Below a defined first power 43 and below a defined first speed 44, the motor vehicle internal combustion engine 51 is in a first operating range 39. The first operating range 39 is designed as a central switching-off operating range. Above the defined first power 43 and below a second defined power 45, and above the first defined speed 44 and below a second defined speed 46, the motor vehicle internal combustion engine 51 is in a second operating range 40. The second operating range 40 is likewise designed as a central switching-off operating range. The third operating range 41 is delimited by the second defined power 45, the second defined speed 46, a third defined power 47, and a third defined speed 48. The fourth operating range 42 is delimited by the third defined power 47, the third defined speed 48, a maximum power 49, and a maximum speed 50. The various powers and speeds are defined as a function of the corresponding motor vehicle internal combustion engine 51, and vary over ranges which appear meaningful to one skilled in the art.
The device for adjusting a motor vehicle valve train has a different combination of switching positions of the cam elements 11, 12, 13, 14 in each operating range 39, 40, 41, 42. In the first operating range 39 designed as a central switching-off operating range, the first cam element 11 and the fourth cam element 14 are each in their first switching position, and in each case activate the particular valves having the small valve lift. In the first operating range, the second cam element 12 and the third cam element 13 are each in the third switching position, and activate the particular valves having a zero lift.
In the second operating range 40 designed as a central switching-off operating range, the first cam element 11 and the fourth cam element 14 are each in their second switching position, and in each case activate the particular valves having the large valve lift. In the second operating range 40, the second cam element 12 and the third cam element 13 are in the third switching position, and activate the particular valves having a zero lift For this purpose, during a transition from the first operating range 39 into the second operating range 40, the control (and regulation) unit 35 switches the first cam element 11 and the fourth cam element 14 in each case from the first switching position into the second switching position by means of the actuator device 37, and thus changes the valve lifts of the valves of the first and fourth cylinders which are activated by the first cam element 11 and the fourth cam element 14, respectively, from the small valve lift to the large valve lift.
In the third operating range 41, all four cam elements 11, 12, 13, 14 are switched into the same switching position. In the third operating range 41, the cam elements 11, 12, 13, 14 are each in their first switching position, and in each case activate the particular valves having a small valve lift. For this purpose, during a transition from the second operating range 40 into the third operating range 41, the control (and regulation) unit 35 switches the first cam element 11 and the fourth cam element 14 in each case from the second switching position into the first switching position by means of the actuator device 37, and thus changes the valve lifts of the valves of the first and fourth cylinders which are activated by the first cam element 11 and the fourth cam element 14, respectively, from the large valve lift to the small valve lift. In addition, during the transition from the second operating range 40 into the third operating range 41, the control (and regulation) unit 35 switches the second cam element 12 and the third cam element 13 in each case from the third switching position into the first switching position by means of the actuator device 37, and thus changes the valve lifts of the valves of the second and third cylinders which are activated by the second cam element 12 and the third cam element 13, respectively, from zero lift to the small valve lift.
All four cam elements 11, 12, 13, 14 are switched into the same switching position in the fourth operating range 42. In the fourth operating range 41, all cam elements 11, 12, 13, 14 are in each case switched into their second switching position, and in each case activate the particular valves having a large valve lift. For this purpose, during a transition from the third operating range 41 into the fourth operating range 42, the control (and regulation) unit 35 switches the first cam element 11, the second cam element 12, the third cam element 13, and the fourth cam element 14 in each case from the first switching position into the second switching position by means of the actuator device 37, and thus changes the valve lifts of the valves of the first, second, third, and fourth cylinders which are activated by the first cam element 11, the second cam element 12, the third cam element 13, and the fourth cam element 14, respectively, from the small valve lift to the large valve lift.
In principle, it is likewise conceivable for individual operating ranges 39, 40, 41, 42 to be skipped, in that, for example, switching the corresponding cam element 11, 12, 13, 14 is temporarily skipped and is not carried out until, for example, a transition into the corresponding next operating range 39, 40, 41, 42 or the operating range which follows it. It is conceivable for the control unit 35 to skip individual operating ranges 39, 40, 41, 42 or to skip switching of the corresponding cam elements 11, 12, 13, 14 into the individual operating ranges, based on engine parameters such as load torque or the like.
In principle, of course, any other switching of the cam elements 11, 12, 13, 14 into the various operating ranges 39, 40, 41, 42 is conceivable which appears meaningful to one skilled in the art. Thus, for example, it is conceivable that in the third operating range 41, the first cam element 11 and the fourth cam element 14 are switched into the first switching position, and the second cam element 12 and the third cam element 13 are switched into their second switching position.
The actuator device 37 has mechanical encoding which specifies a defined switching sequence of the cam elements 11, 12, 13, 14. Due to the mechanical encoding of the actuator device 37, a switching sequence of the cam elements 11, 12, 13, 14 is predetermined, and switching of the individual cam elements 11, 12, 13, 14 always follows a set pattern. The individual switching positions of the individual cam elements 11, 12, 13, 14 in the various operating ranges 39, 40, 41, 42 are specified by the mechanical encoding. In a next operating range 39, 40, 41, 42 the switching position of the cam element 11, 12, 13, 14 is always followed by the same switching position. For switching from the one operating range 39, 40, 41, 42 into an adjacent operating range 39, 40, 41, 42, the control (and regulation) unit 35 outputs only one signal for the switching to the actuator device 37, and correct switching of the cam elements 11, 12, 13, 14 is predetermined by the mechanical encoding. Faulty switching or an absence of switching of one of the cam elements 11, 12, 13, 14 is ruled out. Defined switching positions of the cam elements 11, 12, 13, 14 are always present,
The actuator device 37 is provided for switching the cam elements 11, 12, 13, 14 as a function of at least one operating parameter of the motor vehicle internal combustion engine 51. Upon exceeding a defined speed 44, 46, 48 or a defined power 43, 45, 47 of the motor vehicle internal combustion engine 51 which in each case separate two operating ranges 39, 40, 41, 42 from one another, the control unit 35 outputs a signal for switching the appropriate cam elements 11, 12, 13, 14 by means of the actuator device 37.
The above description relates only to the design of the device for adjusting a motor vehicle valve train for a motor vehicle internal combustion engine 51 having four cylinders. A design of the device for adjusting a motor vehicle valve train for a motor vehicle internal combustion engine 51 having a different number of cylinders, for example two cylinders, three cylinders, six cylinders, or eight cylinders, is essentially the same. A different number of cylinders results in an adjusted number of axially displaceable cam elements 11, 12, 13, 14, and thus results in a number of possible combinations of the switching position of the various cam elements 11, 12, 13, 14. Also for a device for adjusting a motor vehicle valve train for a motor vehicle internal combustion engine 51 having more or fewer cylinders, switching of the cam elements 11, 12, 13, 14, individually or in groups, which may be adjusted to the number of cam elements 11, 12, 13, 14 as described above, takes place as described in the exemplary embodiment above. A design of the actuator device 37 and the number and/or configuration of actuators 38 may be provided in a manner that appears meaningful to one skilled in the art.

LIST OF REFERENCE NUMERALS

10 Camshaft
11 Cam element
12 Cam element
13 Cam element
14 Cam element
15 Cam track
16 Cam track
17 Cam track
18 Cam track
19 Cam track
20 Cam track
21 Cam track
22 Cam track
23 Cam track
24 Cam track
25 Cam track
26 Cam track
27 Cam track
28 Cam track
29 Cam track
30 Cam track
31 Cam track
32 Cam track
33 Cam track
34 Cam track
35 Control and/or regulation unit
36 Main axis of rotation
37 Actuator device
38 Actuator
39 Operating range
40 Operating range
41 Operating range
42 Operating range
43 First power
44 First speed
45 Second power
46 Second speed
47 Third power
48 Third speed
49 Maximum power
50 Maximum speed
51 Motor vehicle internal combustion engine
52 Abscissa
53 Ordinate

Claims

What is claimed is:

1. A device for adjusting a motor vehicle valve drive having at least one camshaft (10) provided with at least first and second cam elements (11, 14, 12, 13) arranged on the camshaft in an axially displaceable manner, and having each at least two different cam tracks disposed adjacent one another for actuating a particular valve, the number of cam tracks (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34) for actuating a valve of one of the cam elements (11, 14 i, 12, 13) and the number of cam tracks (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34) for actuating a valve of another of the cam elements (11, 14 i, 12, 13) being different from one another.

2. The device for adjusting a motor vehicle valve drive according to claim 1, wherein the cam elements (11, 12, 13, 14) arranged in an axially displaceable manner in each case have at least two cam tracks (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34) per valve for adjusting a valve lift of at least one valve of a cylinder.

3. The device for adjusting a motor vehicle valve drive according to claim 1, wherein at least one of the cam elements (12, 13) has at least one cam track (19, 20, 21, 22, 23, 24, 25, 26) providing for a valve lift, and has one cam track (31, 32, 33, 34) providing for zero lift.

4. The device for adjusting a motor vehicle valve drive according to claim 3, wherein another of the cam elements (11, 14) has at least one cam track (15, 16, 17, 18, 27, 28, 29, 30) providing for a valve lift and no zero lift cam track.

5. The device for adjusting a motor vehicle valve drive according to claim 1, wherein of the first cam elements (11, 14) each has two cam tracks (15, 16, 17, 18, 27, 28, 29, 30) for activating an associated valve in each case, and of the second elements (12, 13) each has three cam tracks (19, 20, 21, 22, 23, 24, 25, 26, 31, 32, 33, 34) for activating each an associated valve.

6. The device for adjusting a motor vehicle valve drive according to claim 1, wherein the camshaft (10) includes two first and two second axially displaceable cam elements (11, 12, 13, 14), the two first cam elements (11, 14) in each case having two cam tracks for activating a valve, and the two second cam elements (12, 13) in each having three cam tracks for controlling activation of a valve.

7. The device for adjusting a motor vehicle valve drive according to claim 5, wherein the second cam elements (12, 13), which have each three cam tracks (19, 20, 21, 22, 23, 24, 25, 26, 31, 32, 33, 34) for actuating the respective associated valves have each a zero lift cam track (32, 33).

8. The device for adjusting a motor vehicle valve drive according to claim 1, wherein a control unit (35) which is provided for switching the at least the first and second cam elements (11, 12, 13, 14), independently of one another.

9. The device for adjusting a motor vehicle valve drive according to claim 8, wherein the control unit (35) is provided for changing a switching position of at least one of the first and second cam elements (11, 14 i; 12, 13) while maintaining the momentary switching position of the other cam elements (11, 12, 13, 14) in at least one operating state.

10. The device for adjusting a motor vehicle valve drive according to claim wherein, in at least one operating state, at least one of the cam elements (11, 12, 13, 14) has a cam track providing for a valve lift different from that of another of the cam elements (11, 12, 13, 14).