DE102016212480A1 - Variable valve train of a combustion piston engine - Google Patents

Abstract

The invention relates to a variable valve train (1) of a combustion piston engine having at least two functionally identical gas exchange valves (28, 29) per cylinder whose valve lift is predetermined by at least one primary cam (3, 5) and a secondary cam (4, 6) of a camshaft (2) and by means of a switchable drag lever (7, 8) is selectively transferable, which has a primary lever (9, 12) and a secondary lever (10, 13), wherein the primary lever in each case with the associated primary cam (3, 5) in tap contact, and in which the secondary lever (10, 13) is in each case pivotally mounted on the primary lever (9, 12), is in tap contact with the associated secondary cam (4, 6), and via a coupling element (11, 14) adjustable by an adjusting device (34) ) is coupled to the primary lever (9, 12). According to the invention, it is provided that the coupling elements (11) of the drag levers (7) of a first group of functionally identical gas exchange valves (28) and the coupling elements (14) of the drag levers (8) of a second group of functionally identical gas exchange valves (29) in opposite directions (23, 24) are each adjustable in an actuating position, in which the respective secondary lever (10, 13) with the primary levers (9, 12) are coupled, and that a mechanical adjusting device (34) is provided with a main operating element (40), by its adjustment in opposite actuating directions (45, 46) either the coupling elements (11) of the drag lever (7) of the first gas exchange valve group (28) or the coupling elements (14) of the drag lever (8) of the second gas exchange valve group (29) are adjustable in their operating position.

Description

The invention relates to a variable valve train of a combustion piston engine with at least two functionally identical gas exchange valves per cylinder whose valve lift is predetermined by at least one primary cam and a secondary cam of a camshaft and selectively transferable by means of a respective switchable rocker arm, wherein the rocker arms each have a primary lever and a secondary lever, wherein the primary lever is each end supported on a housing side mounted support member and to the valve stem at least one associated gas exchange valve and interposed therebetween with the associated primary cam in Abgriffkontakt, and in which the rocker arms of the secondary lever is pivotally mounted respectively to the primary lever, with the associated secondary cam is in tap contact, and can be coupled via an adjustable by means of an actuator coupling element with the primary lever.

Switchable valve trains of internal combustion piston engines are known in various designs. Thus, valve trains of individual cylinders or groups of cylinders of a combustion piston engine can be deactivated by switching off the transferable valve lift and, in conjunction with switching off the fuel injection for the cylinders in question, reduce the fuel consumption and the CO ₂ and pollutant emissions of the internal combustion engine in part-load operation. On the other hand, the lift characteristics transmittable by valve trains of intake and / or exhaust valves of a combustion piston engine may be changed by stroke switching and thus adjusted to the current operating state of the internal combustion engine depending on operating parameters such as engine speed and engine load, thereby increasing engine output and torque and the specific fuel consumption of the internal combustion piston engine can be reduced.

In turn-off valve drives are usually two relatively displaceable or rotatable components of a switchable Hubübertragungselementes provided, of which one component with the associated cam of a camshaft and the other component with the valve stem of the associated gas exchange valve is in control connection. Both components can be coupled or decoupled via a coupling element, which is usually designed as a coupling pin. In the coupled state, the valve lift of the associated cam is transmitted to the respective gas exchange valve, in the decoupled state, however, not, so that the gas exchange valve then remains closed. The coupling pin is usually guided axially movable in a bore of a component and displaceable in a coupling bore of the other component. By means of a spring element of the coupling pin is held in a rest position and moved by the application of a force against the restoring force of the spring element in an operating position and held there. In turn-off valve drives, the rest position of the coupling pin usually corresponds to the coupled state of the components of the Hubübertragungselementes and the operating position the decoupled state of the components. The turn-off Hubübertragungselementen may be switchable bucket tappets, roller tappet, rocker arm, drag lever or support elements.

At switchable valve drives at least two relatively displaceable or rotatable components of a switchable Hubübertragungselementes are provided, of which the one component with an associated primary cam of a camshaft with a smaller valve lift and with the valve stem of the associated gas exchange valve and the other component with an associated secondary cam of the camshaft greater valve lift or with an additional stroke in actuating connection. Both components can be coupled or decoupled with one another via a coupling element which is usually designed as a coupling pin. In the decoupled state, the valve lift of the primary cam is transferred to the respective gas exchange valve, in the coupled state, however, the valve lift of the secondary cam is transmitted to the gas exchange valve. Again, the coupling pin is usually guided axially movable in a bore of a component and displaceable in a coupling bore of the other component. By means of a spring element of the coupling pin is held in a rest position and moved by the application of a force against the restoring force of the spring element in an operating position and held there. When switchable valve drives the rest position of the coupling pin usually corresponds to the decoupled state of the components of the Hubübertragungselementes and the operating position of the coupled state of the components. The switchable Hubübertragungselementen are usually switchable tappets, rocker arms or rocker arms.

The adjustment of coupling elements switchable Hubübertragungselemente is usually hydraulically by a leading to pressure chambers of the coupling elements switching pressure line is connected, for example by means of a magnetic switching valve alternately with an oil pressure source or depressurized. A known embodiment of a provided with a hydraulically adjustable coupling pin switchable drag lever, the in a combustion piston engine for Hubabschaltung a gas exchange valve is provided, the DE 10 2006 057 894 A1 be removed. The DE 10 2006 023 772 A1 on the other hand describes a switchable drag lever with a hydraulically adjustable coupling pin, which is provided in a combustion piston engine for Hubumschaltung a gas exchange valve.

If gas exchange valves of a combustion piston engine are selectively switched off or switched over in groups, separate switching pressure lines, each with an associated switching valve, are required for a hydraulic adjustment of the coupling elements. A corresponding hydraulic adjusting device for groupwise selective adjustment of the coupling elements of a variable valve train in a internal combustion piston engine with two intake valves and two exhaust valves per cylinder is for example in the DE 102 12 327 A1 described. The switchable Hubübertragungselemente the valve gear are formed in this case as a switchable bucket tappets.

Since the arrangement of separate hydraulic switching pressure lines in a cylinder head of a Verbrennenkolbenmotors is relatively difficult and expensive due to cramped space, the invention has for its object to propose a variable valve train of a Verbrennungskolbenmotors of the type mentioned with switchable drag levers functionally identical gas exchange valves, the groups with a space-saving adjusting device are selectively switchable.

The solution to this problem is achieved with a variable valve train, which is defined in two alternative embodiments in claims 1 and 5. Further developments are mentioned in the associated dependent claims.

In a first embodiment of the valve train according to the invention is provided in connection with the features of the preamble of claim 1, that the coupling elements of the drag lever of a first group functionally identical gas exchange valves and the coupling elements of the drag lever of a second group of functionally identical gas exchange valves are adjustable in opposite actuating directions in each case in an actuating position, in which the relevant secondary lever are coupled to the primary levers, and that a mechanically effective adjusting device is provided with a main operating element, by the adjustment in opposite directions of actuation, either the coupling elements of the drag lever of the first group of gas exchange valves or the coupling elements of the drag lever of the second group of gas exchange valves their operating position are adjustable.

The invention is based on a known variable valve train of a combustion piston engine having at least two functionally identical gas exchange valves per cylinder. The functionally identical gas exchange valves may be intake valves or exhaust valves. The valve lift of these functionally identical gas exchange valves is in each case predetermined by at least one primary cam and a secondary cam of a camshaft and selectively transferable by means of a switchable cam follower. The switchable rocker arms each have a primary lever and a secondary lever. The primary lever is each end supported on a housing side mounted support member and opposite to the valve stem of at least one associated gas exchange valve, and is therebetween, for example via a rotatably mounted roller or a sliding surface, with the associated primary cam in tap contact. The respective secondary lever is pivotally mounted on the associated primary lever. He is also, for example via a sliding surface, with the associated secondary cam in Abgriffkontakt, and is coupled via an adjustable by an adjusting device coupling element with the primary lever. In the coupled state of the finger lever, the stroke profile of the secondary cam, which usually has a greater lift height than the primary cam or an additional stroke, is transmitted to the associated gas exchange valve. The additional stroke may be, for example, a Nachhub for exhaust gas recirculation or a decompression stroke in the power stroke to increase the engine braking effect.

As an alternative to the usual in the prior art hydraulic switching of the drag lever to allow alternately switching the drag lever of two groups functionally identical gas exchange valves, the coupling elements of the drag lever of the first group functionally identical gas exchange valves and the coupling elements of the drag lever of the second group functionally identical gas exchange valves in opposite directions each adjustable in an actuating position in which the respective secondary levers are coupled to the primary levers. For this purpose, a mechanically effective adjusting device with a main actuating element is provided by the adjustment in opposite directions of actuation, either the coupling elements of the drag lever of the first group of gas exchange valves or the coupling elements of the drag lever of the second group of gas exchange valves are adjustable in their operating position.

By this valve train, the arrangement of separate switching pressure lines within the cylinder head housing and of pressure oil passages in the support elements and the finger levers as well as the use of solenoid valves for Control of the pressures in the switching pressure lines Cost-saving avoided.

In a known embodiment of the finger follower, each with a centrally located primary lever and a frame-shaped secondary lever with the primary lever laterally comprehensive outer levers, the respective coupling element is preferably formed as a coupling pin, which is guided with axially parallel alignment to the camshaft longitudinally displaceable in the primary lever, and on both sides of the outer lever of the secondary lever penetrates in each case an opening. The openings of the drag levers of both groups of gas exchange valves each extend slit-shaped in the respective adjustment direction of the coupling bolt and have a lying in the rest position of the coupling bolt against the stroke direction of the secondary lever recess. Due to said recess, the secondary lever can spring in with the coupling pin located in the rest position relative to the primary lever, so that the stroke profile of the secondary cam is then not transmitted to the valve stem of the associated gas exchange valve.

The drag levers of both groups of functionally identical gas exchange valves can advantageously also be of identical construction, in that the openings in the outer levers of the secondary lever each extend in the form of slots in both actuating directions of the coupling bolts. Although the openings in the outer levers of the secondary lever are used in the actuation position only in one direction in the displacement of the coupling pin, in addition to manufacturing and logistical advantages has the identical design of the drag lever but the significant advantage that it is not confused during assembly of the cylinder head may come from drag levers, and thus a malfunction of the valve train is reliably excluded.

The adjusting device has as a main operating element preferably a rotatable via a controllable drive motor shift shaft, which is arranged axially parallel to the camshaft on the cam levers, and on which a pair of shift levers is arranged for each of the switchable drag levers. The two shift levers comprise the two outer levers of the associated secondary lever in each case on the longitudinal side facing away from the respective adjustment direction of the respective coupling bolt and can be brought into actuating connection with the latter by rotation of the selector shaft in the direction of the relevant coupling bolt. The shift shaft with the shift levers can thus be arranged to save space within the valve cover of the cylinder head.

The second embodiment of the invention relates to a variable valve train of a Verbrennungskolbenmotors with at least two functionally identical gas exchange valves per cylinder, whose valve lift is determined by at least one primary cam and a secondary cam of a camshaft and selectively transferable by means of a switchable cam lever, wherein the cam followers each have a primary lever and a Have secondary lever, wherein the primary lever is each end supported on a housing side mounted support member and opposite to the valve stem of the associated gas exchange valve and therebetween with the associated primary cam in Abgriffkontakt, and is mounted on the rocker arms of the secondary lever each pivotally mounted on the primary lever, with the associated secondary cam is in tap contact, and can be coupled via an adjustable by means of an actuator coupling element with the primary lever.

To solve the technical problem posed is provided in this second embodiment, that the coupling elements of the drag lever of a first group functionally identical gas exchange valves and the coupling elements of the drag lever a second group functionally identical gas exchange valves in the same direction of adjustment in each case an actuating position are adjustable, in which the relevant secondary lever with the Primary levers are coupled, and that a mechanically effective adjusting device is provided with a main operating element, by the stepwise adjustment in the same direction of actuation first the coupling elements of the rocker arms of a group of gas exchange valves and then additionally the coupling elements of the rocker arms of the other group of gas exchange valves are adjustable in their operating position ,

In order to allow a sequential switching of the finger follower of two groups of functionally identical gas exchange valves as an alternative to a hydraulic switching of the finger follower, in this second, alternative embodiment of the invention, the coupling elements of the finger levers of the first group functionally identical gas exchange valves and the coupling elements of the second group functionally identical gas exchange valves in the same direction of adjustment each adjustable in an actuating position, in which the respective secondary levers are coupled to the primary levers. In addition, a mechanically effective adjusting device with a main actuating element is provided for this purpose, by the stepwise adjustment in the same direction of actuation first the coupling elements of the drag lever of a group of gas exchange valves and then additionally the coupling elements of the drag lever of the other group of gas exchange valves are adjustable in their operating position. Also, by this valve gear according to the invention, the arrangement is separate Switching pressure lines within the cylinder head housing as well as pressure oil ducts in the support elements and the rocker arms as well as the use of solenoid valves for controlling the pressures in the switching pressure lines avoided.

In a known arrangement of the finger follower, each with a centrally located primary lever and a frame-shaped secondary lever with the primary lever laterally comprehensive outer levers the respective coupling element is preferably designed as a coupling pin, which is guided with axially parallel alignment to the camshaft longitudinally displaceable in the primary lever, and on both sides of the outer lever of the secondary lever penetrates in each case an opening. The openings of the drag levers of both groups of gas exchange valves each extend slit-shaped in the direction of adjustment of the coupling bolt and have a lying in the rest position of the coupling bolt against the stroke direction of the secondary lever recess.

The adjusting device has as a main operating element preferably rotatable by means of a controllable drive motor switching shaft which is arranged axially parallel to the camshaft on the cam levers, and on which a pair of switching levers is arranged for each of the switchable cam followers. The two shift levers of each drag lever enclose the outer lever of the associated secondary lever circumferentially in groups staggered on the direction of adjustment of the respective coupling bolt remote longitudinal side and can be brought by a graduated rotation of the switching shaft in the direction of the respective coupling bolt with this in control connection. As a result, the shift shaft can be arranged with the shift levers to save space within the valve cover of the cylinder head.

In the case of the two alternative embodiments of the valve drive according to the invention, the coupling bolts of the rocker arms are preferably durable in each case by at least one spring element in its rest position. As a result, the coupling pin in the unactuated state are always in their rest position, in which the secondary levers are decoupled from the primary levers, and they return automatically after loosening the contact with the associated levers of the shift shaft in this back.

According to another embodiment, it is preferably provided that the coupling bolts of the rocker arms each have a radial extension, which engages with play in a central recess of the respective primary lever. As a result, the coupling bolts are axially fixed in the associated drag lever in a simple manner.

The drive motor for rotating the shift shaft is preferably designed as a controllable electric motor. In order to limit the size and power consumption of the drive motor and to simplify its controllability, the drive shaft of the drive motor is preferably via a reduction gear with the shift shaft in drive connection. The reduction gear between the drive motor and the shift shaft may be formed, for example, as a worm gear with a fixedly arranged on the drive shaft of the drive motor worm and a rotatably mounted on the shift shaft worm.

In order to simultaneously effect the switching over of all drag levers of a group of functionally identical gas exchange valves by a rotation of the control shaft, the shift levers are preferably mounted pivotably on the selector shaft and rotationally fixed in each case via at least one torsion spring.

As a result, the coupling pin those drag levers whose associated primary and secondary cams are tapped in the base circle of the primary and secondary levers, immediately shifted to their operating position, whereas the coupling pin of the remaining rocker arm by the torsion springs of the lever only in the direction of adjustment by spring force be biased, and only be moved to the operating position upon reaching the overlap of the basic circuits of primary and secondary cams in the tap by the associated primary and secondary levers.

It is understood in the knowledge of the invention of itself that the spring stiffness of the torsion springs is significantly greater than the spring stiffness of those spring elements by means of which the coupling bolts are held in their rest position or pushed back into this, to ensure the switching of the rocker arms.

In order to achieve a high spring stiffness in conjunction with compact dimensions, the torsion springs are preferably designed as leg springs, one leg of which is respectively supported on the respective shift lever, and whose other leg is respectively supported on the shift shaft and / or upon rotation of the shift shaft an associated stop on the cylinder head of the internal combustion piston engine comes into supporting contact.

Both embodiments of the valve train according to the invention are preferably used in a combustion piston engine having two functionally identical gas exchange valves per cylinder, which are actuated in each case via two separate rocker arms and alternately one of two Groups are assigned selectively switchable gas exchange valves, since the advantage over a hydraulic switching of the cam follower over two closely branched switching pressure lines in the cylinder head is particularly large.

However, the two embodiments of the valve train according to the invention can also be used in a combustion piston engine having two functionally identical gas exchange valves per cylinder, which are each operable via two separate rocker arms or a common drag lever and cylinders are assigned to one of two groups selectively reversible gas exchange valves, even if the advantage over a hydraulic switching of the drag levers over two branched switching pressure lines in the cylinder head in this case is less large.

Also possible is an application of the valve train according to the invention in a combustion piston engine with only one functionally identical gas exchange valve per cylinder, which is actuated in each case via a drag lever and cylinder is associated with one of two groups of selectively switchable gas exchange valves.

To further illustrate the invention, the description is a drawing attached to two embodiments. In these shows

1 1 is a perspective view of a first embodiment of a valve drive according to the invention of a combustion piston engine with two non-switched rocker arms;

1a a non-switched rocker arm of the valve train according to 1 .

1b according to the rocker arm 1a in a longitudinal center section,

2 according to the valve train 1 with a switched first rocker arm,

2a a switched first drag lever of the valve train according to 2 .

3 according to the valve train 1 with a switched second drag lever,

3a a switched second drag lever of the valve train according to 3 .

4 a second embodiment of a valve gear according to the invention of a combustion piston engine with two non-switched rocker arms, and

4a a non-switched rocker arm of the valve train according to 4 ,

In the 1 Pictured first embodiment of a valve train according to the invention 1 a combustion piston engine has a camshaft 2 , two groups of switchable rocker arms 7 . 8th , two groups of functionally identical gas exchange valves 28 . 29 and an actuator 34 for selective switching of the rocker arms 7 . 8th , For better clarity are in 1 but only a gas exchange valve 28 . 29 each group and the associated drag levers 7 . 8th displayed. At the gas exchange valves 28 . 29 These can be either intake valves or exhaust valves.

The camshaft 2 is in drive manner not shown manner with the crankshaft of the internal combustion piston engine and has for each of the gas exchange valves 28 . 29 one central primary cam each 3 . 5 and two axially on both sides next to this primary cam 3 . 5 arranged secondary cams 4 . 6 on. The switchable drag levers 7 . 8th each have a primary lever 9 . 12 and a secondary lever 10 . 13 on, each via an associated coupling element 11 . 14 can be coupled together. In decoupled state of the relevant rocker arm 7 . 8th becomes the stroke course of the respective primary cam 3 . 5 to the relevant gas exchange valve 28 . 29 transfer. In the coupled state of the relevant finger lever 7 . 8th becomes the stroke course of the respective secondary cam 4 . 6 to the relevant gas exchange valve 28 . 29 transfer.

First, the structure of the drag lever 7 . 8th based on 1a and 1b explained in more detail. In the perspective view of 1a and the sectional view of 1b are in just one illustration the rocker arms 7 . 8th both groups of gas exchange valves 28 . 29 represented, since these are designed identical, whereby confusion during assembly of the relevant cylinder head can be avoided.

The rocker arms 7 . 8th each have a centrally located primary lever 9 . 12 and a frame-shaped secondary lever 10 . 13 with two the primary lever 9 . 12 laterally comprehensive outer levers 15 . 16 on. The primary lever 9 . 12 is on each side via a hydraulic support element 32 . 33 on the cylinder head housing, not shown, and opposite to the valve stem 30 . 31 the associated gas exchange valve 28 . 29 supported. In between is the primary lever 9 . 12 via a rotatably mounted roller 17 in tap contact with the associated primary cam 3 . 5 the camshaft 2 , The secondary lever 10 . 13 is pivotally attached to the respective primary lever at the valve end 9 . 12 stored and stands, pressed on at least one trained as a leg spring pressure spring 18 . over at the two outer levers 15 . 16 trained sliding surfaces 19 . 20 with the assigned secondary cams 4 . 6 the camshaft 2 in tap contact.

As a coupling element for coupling the secondary lever 10 . 13 with the primary lever 9 . 12 is in each case a coupling pin 11 . 14 provided, with the axis-parallel alignment with the camshaft 2 longitudinally displaceable in the primary lever 9 . 12 is guided. The coupling pin 11 . 14 penetrates the two outer levers 15 . 16 of the secondary lever 10 . 13 on both sides in each case an opening 21 , Due to the identical design of the drag lever 7 . 8th the openings extend 21 in the outer levers 15 . 16 of the secondary lever 10 . 13 slit-shaped in both longitudinally opposite directions of adjustment 23 . 24 the coupling pin 11 . 14 , In the in 1a and 1b shown rest position of the coupling pin 11 . 14 have the openings 21 one each against the stroke direction of the secondary lever 10 . 13 extending recess 22 on, leaving the secondary lever 10 . 13 without a stroke transmission relative to the primary lever 9 . 12 can spring, so the secondary lever 10 . 13 from the primary lever 9 . 12 is decoupled.

In the function as drag lever 7 the first group of gas exchange valves 28 becomes the relevant secondary lever 10 with the primary lever 9 coupled by the coupling pin 11 from his rest position in the first direction 23 is moved to the outside in its operating position. In the function as drag lever 8th the second group of gas exchange valves 29 becomes the relevant secondary lever 13 with the primary lever 12 coupled by the coupling pin 14 from its rest position in the second direction of adjustment 24 is moved to the inside in its operating position.

The coupling bolts 11 . 14 the rocker arm 7 . 8th are each held by at least one in the figures unrecognizable spring element in its rest position or pushed back into this. In 1b it can be seen that the coupling bolts 11 . 14 the rocker arm 7 . 8th each in a trained as a longitudinal slot guide slot 25 longitudinally movable in the respective primary lever 9 . 12 are guided. In addition, goes out 1b apparent that the coupling bolts 11 . 14 via a centrally formed on this, in this case formed by a ring land radial extension 26 , the spielbehaftet in a central groove-shaped recess 27 in the lead setting 25 of the respective primary lever 9 . 12 engages, axially in the relevant cam follower 7 . 8th are fixed.

The adjusting device 34 for switching the rocker arms 7 . 8th is mechanically effective and includes a drive motor 35 , a shift shaft 40 and on the shift shaft 40 arranged pairs of levers 41 . 42 ; 43 . 44 , The drive motor 35 is preferably designed as a controllable electric motor. The shoot shaft 36 of the drive motor 35 is via a reduction gear 37 with the switching shaft 40 in drive connection. The reduction gear 37 is exemplified as a worm gear, the worm 38 rotatably on the drive shaft 36 of the drive motor 35 is attached, and its worm wheel 39 rotatably on the shift shaft 40 is arranged. The shift shaft 40 is axially parallel to the camshaft 2 above the drag lever 7 . 8th arranged. The shifters 41 . 42 ; 43 . 44 are in pairs over the rocker arms 7 . 8th circumferentially and axially on the shift shaft 40 arranged that these are the outside levers 15 . 16 the associated secondary lever 10 . 13 each on the respective adjustment direction 23 . 24 the relevant coupling bolt 11 . 14 surround the opposite longitudinal side.

Upon rotation of the shift shaft 40 according to the marked first direction of rotation arrow 45 the shifters come 41 . 42 the first group of gas exchange valves 28 in actuating connection with the coupling bolts 11 the associated first drag lever 7 and move the coupling bolts 11 upon further rotation of the switching shaft 40 in their operating position. As a result, in each case the respective secondary lever 10 with the primary lever 9 coupled, and thus the stroke of the associated secondary cam 4 to the relevant gas exchange valve 28 transfer.

By a rotation of the switching shaft 40 in the opposite direction of rotation according to the indicated second direction of rotation arrow 46 the shifters come 43 . 44 the second group of gas exchange valves 29 in actuating connection with the coupling bolts 14 the associated second rocker arm 8th and move the coupling bolts 14 upon further rotation of the switching shaft 40 in their operating position. As a result, in each case the respective secondary lever 13 with the primary lever 12 coupled, and thus the stroke of the associated secondary cam 6 to the relevant gas exchange valve 29 transfer. Thus, the drag levers 7 . 8th of the valve train 1 groupwise alternatively switchable.

The shifters 41 . 42 ; 43 . 44 are each pivotable on the shift shaft 40 stored and each have a torsion spring 47 . 48 ; 49 . 50 elastic on this drehfixiert. As a result, upon rotation of the shift shaft 40 the coupling bolts 11 . 14 those drag levers 7 . 8th , their assigned primary and secondary cams 3 . 4 ; 5 . 6 just in the base circle of the primary and secondary levers 9 . 10 ; 12 . 13 be tapped, immediately moved to their operating position. The coupling bolts 11 . 14 the remaining drag lever 7 . 8th be through the torsion springs 47 . 48 ; 49 . 50 the shifter 41 . 42 ; 43 . 44 initially only in the respective direction of adjustment 23 . 24 biased and only when the overlap of the primary and secondary cams is reached 3 . 4 ; 5 . 6 in the tap by the associated primary and secondary levers 9 . 10 ; 12 . 13 moved to the operating position. The torsion springs 47 . 48 ; 49 . 50 are exemplified as a torsion spring, one leg of each of the respective shift lever 41 . 42 ; 43 . 44 is supported, and the other leg respectively on the shift shaft 40 is supported and / or upon rotation of the shift shaft 40 in the respective direction of rotation 45 . 46 with an associated stop on the cylinder head of the internal combustion piston engine comes into support contact.

In 2 is the valve train 1 of the internal combustion piston engine mapped in an operating state in which the shift shaft 40 the adjusting device 34 through the drive motor 35 so far in the first direction of rotation 45 turned that is the coupling pin 11 the rocker arm 7 the first group of gas exchange valves 28 over the assigned shift lever 41 . 42 are moved to their operating position. As a result, in each case the respective secondary lever 10 with the primary lever 9 coupled so that the stroke course of the associated secondary cam 4 to the relevant gas exchange valve 28 is transmitted. A rocker 7 the first group of gas exchange valves 28 with one in the first direction 23 in the operating position shifted coupling pin 11 is in 2a displayed.

In 3 is the valve train 1 of the internal combustion piston engine mapped in an operating state in which the shift shaft 40 the adjusting device 34 through the drive motor 35 so far in the second direction of rotation 46 turned that is the coupling pin 14 the rocker arm 8th the second group of gas exchange valves 29 over the assigned shift lever 43 . 44 are moved to their operating position. As a result, in each case the respective secondary lever 13 with the primary lever 12 coupled so that the stroke course of the associated secondary cam 6 to the relevant gas exchange valve 29 is transmitted. A rocker 8th the second group of gas exchange valves 29 with one in the second direction of adjustment 24 in the operating position shifted coupling pin 14 is in 3a displayed.

An in 4 shown second embodiment of a valve train according to the invention 1' A combustion piston engine differs from the first embodiment of the valve train 1 according to 1 by slightly different trained drag lever 7 ' . 8th' and by another arrangement, the shift lever 41 ' . 42 ' . 43 ' . 44 ' on the stem 40 the adjusting device 34 ' ,

In the perspective view of 4a are due to their identical design at the same time the rocker arms 7 ' . 8th' both groups of gas exchange valves 28 . 29 shown. With otherwise the same structure of the drag lever 7 ' . 8th' as in the execution of the rocker arms 7 . 8th according to 1a the openings extend 21 ' in the outer levers 15 . 16 of the secondary lever 10 . 13 , starting from the in 4a shown rest position of the coupling pin 11 . 14 , now slit-shaped only in the longitudinal direction outward direction of adjustment 23 the coupling pin 11 . 14 , Both in the function as a drag lever 7 ' the first group of gas exchange valves 28 as well as in function as drag lever 8th' the second group of gas exchange valves 29 becomes the relevant secondary lever 10 . 13 with the primary lever 9 . 12 coupled by the respective coupling pin 11 . 14 from the rest position in the direction of adjustment 23 is moved to the outside in the operating position.

The shifters 41 ' . 42 '; 43 ' . 44 ' the adjusting device 34 ' are now in pairs over the rocker arms 7 ' . 8th' staggered circumferentially groupwise and axially on the shift shaft 40 arranged that these are the two outer levers 15 . 16 the associated secondary lever 10 . 13 each on the direction of adjustment 23 the coupling pin 11 . 14 surround the opposite longitudinal side. In the present case are the rocker arms 7 ' the first group of gas exchange valves 28 associated shift lever 41 ' . 42 ' circumferentially farther away from the respective coupling bolts 11 on the stem 40 arranged as the towing levers 8th' the second group of gas exchange valves 29 associated shift lever 43 ' . 44 ' from the assigned coupling bolts 14 are removed.

As a result, come with a rotation of the shift shaft 40 according to the indicated direction of rotation arrow 45 First, the shift lever 43 ' . 44 ' the second group of gas exchange valves 29 in actuating connection with the coupling bolts 14 the assigned drag lever 8th' and move the coupling bolts 14 upon further rotation of the switching shaft 40 in their operating position. As a result, in each case the respective secondary lever 13 with the primary lever 12 coupled, and thus the stroke of the associated secondary cam 6 to the relevant gas exchange valve 29 transfer.

By a further rotation of the switching shaft 40 in the same direction 45 then come the shifters 41 ' . 42 ' the first group of gas exchange valves 28 in actuating connection with the coupling bolts 11 the assigned drag lever 7 ' and move the coupling bolts 11 upon further rotation of the switching shaft 40 in their operating position, whereby each of the respective secondary lever 10 with the primary lever 9 is coupled, and with it the stroke course of the associated secondary cam 4 to the relevant gas exchange valve 28 is transmitted.

Thus, the drag levers 7 ' . 8th' of the valve train 1' groupwise additively switchable. The shifters 41 ' . 42 '; 43 ' . 44 ' are also each pivotable on the shift shaft 40 stored and in each case a trained as a torsion spring torsion spring 47 ' . 48 '; 49 ' . 50 ' elastic on this drehfixiert.

LIST OF REFERENCE NUMBERS

1

 Valve train (first embodiment)

1'

 Valve train (second embodiment)

2

 camshaft

3

 First primary cam

4

 First secondary cam

5

 Second primary cam

6

 Second secondary cam

7, 7 '

 First drag lever

8, 8 '

 Second cam follower

9

 Primary lever of the first rocker arm

10

 Secondary lever of the first rocker arm

11

 Coupling element, coupling pin of the first rocker arm

12

 Primary lever of the second rocker arm

13

 Secondary lever of the second rocker arm

14

 Coupling element, coupling pin of the second rocker arm

15

 First outside lever

16

 Second outer lever

17

 role

18

 Pressure spring, leg spring

19

 First sliding surface

20

 Second sliding surface

21, 21 '

 opening

22

 recess

23

 First directional arrow, first direction of adjustment

24

 Second directional arrow, second direction of adjustment

25

 Guide slot, longitudinal slot

26

 Radial extension, ring bar on the coupling pin

27

 Central recess

28

 First gas exchange valve

29

 Second gas exchange valve

30

 First valve stem

31

 Second valve stem

32

 First support element

33

 Second support element

34, 34 '

 locking device

35

 Drive motor, electric motor

36

 drive shaft

37

 Reduction gear, worm gear

38

 slug

39

 worm

40

 shift shaft

41, 41 '

 First shift lever

42, 42 '

 First shift lever

43, 43 '

 Second gear lever

44, 44 '

 Second gear lever

45

 First direction of rotation arrow, first direction of rotation

46

 Second direction of rotation arrow, second direction of rotation

47, 47 '

 Torsion spring, leg spring

48, 48 '

 Torsion spring, leg spring

49, 49 '

 Torsion spring, leg spring

50, 50 '

 Torsion spring, leg spring

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 102006057894 A1 [0005]
• DE 102006023772 A1 [0005]
• DE 10212327 A1 [0006]

Claims (10)

Variable valve train ( 1 ) of a combustion piston engine with at least two functionally identical gas exchange valves ( 28 . 29 ) per cylinder, the valve lift of each by at least one primary cam ( 3 . 5 ) and a secondary cam ( 4 . 6 ) a camshaft ( 2 ) and by means of a respective switchable rocker arm ( 7 . 8th ) is selectively transferable, the rocker arms ( 7 . 8th ) each have a primary lever ( 9 . 12 ) and a secondary lever ( 10 . 13 ), wherein the primary lever ( 9 . 12 ) each end to a housing side mounted support member ( 32 . 33 ) and opposite to the valve stem ( 30 . 31 ) at least one associated gas exchange valve ( 28 . 29 ) and in-between with the associated primary cam ( 3 . 5 ) is in tap contact, and in the on the rocker arms ( 7 . 8th ) the secondary lever ( 10 . 13 ) each pivotally on the primary lever ( 9 . 12 ) is mounted, with the associated secondary cam ( 4 . 6 ) is in tap contact, as well as via a by means of an adjusting device ( 34 ) adjustable coupling element ( 11 . 14 ) with the primary lever ( 9 . 12 ) can be coupled, characterized in that the coupling elements ( 11 ) the drag lever ( 7 ) a first group of functionally identical gas exchange valves ( 28 ) and the coupling elements ( 14 ) the drag lever ( 8th ) a second group of functionally identical gas exchange valves ( 29 ) in opposite directions ( 23 . 24 ) are each adjustable in an actuating position, in which the respective secondary lever ( 10 . 13 ) with the associated primary levers ( 9 . 12 ), and in that a mechanically acting adjusting device ( 34 ) with a main operating element ( 40 ) is provided, by its adjustment in opposite directions of actuation ( 45 . 46 ) either the coupling elements ( 11 ) the drag lever ( 7 ) of the first group of gas exchange valves ( 28 ) or the coupling elements ( 14 ) the drag lever ( 8th ) of the second group of gas exchange valves ( 29 ) are adjustable in their operating position. Valve train ( 1 ) according to claim 1, characterized in that in one embodiment the drag levers ( 7 . 8th ) each having a centrally located primary lever ( 9 . 12 ) and a frame-shaped secondary lever ( 10 . 13 ) and with two the primary lever ( 9 . 12 ) lateral outer levers ( 15 . 16 ) the respective coupling element ( 11 . 14 ) is designed as a coupling pin, which with axis-parallel alignment with the camshaft ( 2 ) longitudinally displaceable in the primary lever ( 9 . 12 ) is guided, and which axially on both sides of the two outer lever ( 15 . 16 ) of the secondary lever ( 10 . 13 ) in each case an opening ( 21 ) penetrates, whereby the two openings ( 21 ) the drag lever ( 7 . 8th ) of both groups of gas exchange valves ( 28 . 29 ) each slot-shaped in the respective adjustment direction ( 23 . 24 ) of the coupling bolt ( 11 . 14 ) and one in the rest position of the coupling bolt ( 11 . 14 ) against the stroke direction of the secondary lever ( 10 . 13 ) lying recess ( 22 ) exhibit. Valve train ( 1 ) according to claim 2, characterized in that the drag levers ( 7 . 8th ) of both groups of functionally identical gas exchange valves ( 28 . 29 ) are constructed identically by the openings ( 21 ) in the two outer levers ( 15 . 16 ) of the secondary lever ( 10 . 13 ) each slot-shaped in both directions ( 23 . 24 ) the coupling pin ( 11 . 14 ). Valve train ( 1 ) according to one of claims 1 to 3, characterized in that the adjusting device ( 34 ) as the main actuating element by means of a controllable drive motor ( 35 ) rotatable shaft ( 40 ), that the switching shaft ( 40 ) parallel to the axis of the camshaft ( 2 ) over the rocker arms ( 7 . 8th ) is arranged, and that at the switching shaft ( 40 ) for each of the switchable drag levers ( 7 . 8th ) a pair of levers ( 41 . 42 ; 43 . 44 ) is arranged, which the outer lever ( 15 . 16 ) of the associated secondary lever ( 10 . 13 ) each on the respective adjustment direction ( 23 . 24 ) of the relevant coupling bolt ( 11 . 14 ) facing away from the longitudinal side, and which by a rotation ( 45 . 46 ) of the switching shaft ( 40 ) in the direction of the respective coupling bolt ( 11 . 14 ) Can be brought into Stellverbindung with this. Variable valve train ( 1' ) of a combustion piston engine with at least two functionally identical gas exchange valves ( 28 . 29 ) per cylinder, the valve lift of each by at least one primary cam ( 3 . 5 ) and a secondary cam ( 4 . 6 ) a camshaft ( 2 ) and by means of a switchable rocker arm ( 7 ' . 8th' ) is selectively transferable, the rocker arms ( 7 . 8th ) each have a primary lever ( 9 . 12 ) and one Secondary lever ( 10 . 13 ), wherein the primary lever ( 9 . 12 ) each end to a housing side mounted support member ( 32 . 33 ) and opposite to the valve stem ( 30 . 31 ) at least one associated gas exchange valve ( 28 . 29 ) and in-between with the associated primary cam ( 3 . 5 ) is in tap contact, and in the on the rocker arms ( 7 . 8th ) the secondary lever ( 10 . 13 ) each pivotally on the primary lever ( 9 . 12 ) is mounted, with the associated secondary cam ( 4 . 6 ) is in tap contact, as well as via a by means of an adjusting device ( 34 ' ) adjustable coupling element ( 11 . 14 ) with the primary lever ( 9 . 12 ) can be coupled, characterized in that the coupling elements ( 11 ) the drag lever ( 7 ' ) a first group of functionally identical gas exchange valves ( 28 ) and the coupling elements ( 14 ) the drag lever ( 8th' ) a second group of functionally identical gas exchange valves ( 29 ) in the same direction ( 23 ) are each adjustable in an actuating position, in which the respective secondary lever ( 10 . 13 ) with the primary levers ( 9 . 12 ), and in that a mechanically acting adjusting device ( 34 ' ) with a main operating element ( 40 ) is provided by the stepwise adjustment in the same direction of actuation ( 45 ) first the coupling elements ( 14 ) the drag lever ( 8th' ) of a group of gas exchange valves ( 29 ) and then additionally the coupling elements ( 11 ) the drag lever ( 7 ' ) of the other group of gas exchange valves ( 28 ) are adjustable in their operating position. Valve train ( 1' ) according to claim 5, characterized in that in one embodiment the drag levers ( 7 ' . 8th' ) each having a centrally located primary lever ( 9 . 12 ) and a frame-shaped secondary lever ( 10 . 13 ) and with two the primary lever ( 9 . 12 ) lateral outer levers ( 15 . 16 ) the respective coupling element ( 11 . 14 ) is designed as a coupling pin, which with axis-parallel alignment with the camshaft ( 2 ) longitudinally displaceable in the primary lever ( 9 . 12 ) is guided, and which axially on both sides of the two outer lever ( 15 . 16 ) of the secondary lever ( 10 . 13 ) in each case an opening ( 21 ' ) penetrates, whereby the two openings ( 21 ' ) the drag lever ( 7 ' . 8th' ) of both groups of gas exchange valves ( 28 . 29 ) each slot-shaped in the respective adjustment direction ( 23 ) of the coupling bolt ( 11 . 14 ) and one in the rest position of the coupling bolt ( 11 . 14 ) against the stroke direction of the secondary lever ( 10 . 13 ) lying recess ( 22 ) exhibit. Valve train ( 1' ) according to claim 5 or 6, characterized in that the adjusting device ( 34 ' ) as the main actuating element by means of a controllable drive motor ( 35 ) rotatable shaft ( 40 ), that the switching shaft ( 40 ) parallel to the axis of the camshaft ( 2 ) over the rocker arms ( 7 ' . 8th' ) is arranged, that at the switching shaft ( 40 ) for each of the switchable drag levers ( 7 ' . 8th' ) a pair of levers ( 41 ' . 42 '; 43 ' . 44 ' ) is arranged, which the outer lever ( 15 . 16 ) of the associated secondary lever ( 10 . 13 ) in groups staggered on the direction of adjustment ( 23 ) of the relevant coupling bolt ( 11 . 14 ) facing away from the longitudinal side, and which by a stepped rotation ( 45 ) of the switching shaft ( 40 ) in the direction of the respective coupling bolt ( 11 . 14 ) Can be brought into Stellverbindung with this. Valve train ( 1 . 1' ) according to any one of claims 2 to 4 and 6 or 7 , characterized in that the coupling bolts ( 11 . 14 ) the drag lever ( 7 . 8th ; 7 ' . 8th' ) are each held by at least one spring element in its rest position. Valve train ( 1 . 1' ) according to any one of claims 2 to 4 and 6 to 8th , characterized in that the coupling bolts ( 11 . 14 ) the drag lever ( 7 . 8th ; 7 ' . 8th' ) each have a centrally disposed radial extension ( 26 ), which play in a central recess ( 27 ) of the respective primary lever ( 9 . 12 ) engages, and thereby axially in the respective cam followers ( 7 . 8th ; 7 ' . 8th' ) are fixed. Valve train ( 1' ) according to one of the preceding claims, characterized in that the shift levers ( 41 . 42 . 43 . 44 ; 41 ' . 42 ' . 43 ' . 44 ' ) pivotable on the shift shaft ( 40 ) and in each case via at least one torsion spring ( 47 . 48 . 49 . 50 ; 47 ' . 48 ' . 49 ' . 50 ' ) are torsionally fixed on this drehfestiert that the torsion springs ( 47 . 48 . 49 . 50 ; 47 ' . 48 ' . 49 ' . 50 ' ) are designed as torsion springs, one leg of which in each case at the respective shift lever ( 41 . 42 . 43 . 44 ; 41 ' . 42 ' . 43 ' . 44 ' ) is supported, and the other leg respectively on the shift shaft ( 40 ) or during a rotation ( 45 . 46 ) of the switching shaft ( 40 ) comes into supporting contact with the cylinder head of the internal combustion piston engine.

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