DE102016201514A1 - Variable valve train for a reciprocating internal combustion engine - Google Patents

Abstract

Proposed is a variable valve train (1) for a reciprocating internal combustion engine, with a camshaft (5) which moves at least a part of the gas exchange valves (24) mounted in a housing, in particular a cylinder head head (2) with the interposition of a respective rocker arm (4), wherein each rocker arm (4) rotatably mounted but axially secured on a displaceable sliding axis (3) arranged in the housing, the camshaft (5) per gas exchange valve (24) has at least two cams (7, 8) of different contour and wherein means (9) for shifting the sliding axis (3) in at least two switching position (A, B) are provided, so that each rocker arm (4) in the first switching position under the first and in the second switching position under the second cam (7, 8) , In order to achieve a simple and cost-effective locking in the individual switching positions, the invention proposes that the sliding axis (3) is held in each of its switching position by a locking device (25).

Description

Field of the invention

The invention relates to a variable valve train for a reciprocating internal combustion engine, with a camshaft which moves at least a portion of the mounted in a housing, in particular in a cylinder head gas exchange valves with the interposition of each rocker arm, each rocker arm rotatable, but axially secured on a arranged in the housing , the sliding cam axle is mounted, wherein the camshaft per gas exchange valve at least two cams of different contour and wherein means for shifting the sliding axis are provided in at least two switching position, so that each rocker arm in the first switching position under the first and in the second switching position under the second cam is arranged.

State of the art

A generic valve train goes off 1 of the DE 10 2011 101 871 B1 out. In this case, sitting on a stationary axis rotatably a rocking lever, which runs with his arm over a arranged on a camshaft cam package. The rocker arm is displaceable along the axis between two switching points. For this purpose, it has at its end facing away from the arm on a control pin which engages permanently in a cam groove of a sleeve, which in turn sits on a further shaft with a multi-tooth guide and is rotatable to the adjustment. The adjustment is mainly used for the inlet gas exchange valves to change their stroke.

The aforementioned valve train is not suitable for mass production due to its complex structure. There are ultimately three shafts / axes necessary to illustrate the variability, in particular the formation of the shaft with the multi-tooth guidance is complex and requires additional space, which is often not available in compact-build internal combustion engines, for example. In 1- or 2-cylinder design , In addition, each rocker arm requires a control disk, in which a precise to be produced control contour must be incorporated.

Disclosure of the invention

It is an object of the invention to provide a valve train of the aforementioned type, which is good for a large-scale production and in particular is inexpensive to manufacture.

This object is achieved in that the sliding axis is held in each switching position by a locking device. Advantageous embodiments are given in the claims dependent thereon, which in themselves or in various combinations with each other can represent an aspect of the invention.

The adjustment is mainly used for the inlet gas exchange valves to vary their stroke length, opening duration and the opening and closing time. However, it is also conceivable to provide both inlet and outlet valves with an adjustable sliding axis.

With the present invention, a simple and consisting of a few components locking device is provided which does not require increased switching times for the displacement of the sliding axis. Thus, the proposed solution is also suitable for use in motorcycle engines, preferably, but not exclusively, for a one-cylinder internal combustion engine with a valve train in DOHC-4V design, with an OHC or a 2V valve train is eligible. In the case of, for example, a two-cylinder internal combustion engine, both cylinders can likewise be supplied by the one sliding axis system with the locking device according to the invention. However, it is also conceivable and intended to supply each cylinder with its own sliding axis system.

Preferably, two different cam contours are used for each (inlet) gas exchange valve, wherein one cam contour can cause a large valve lift and the other a small valve lift or even zero lift.

For the invention, it does not matter which cam contour is "activated" in which setting position.

The valve train according to the invention can be subsequently very easily in existing designs of internal combustion engines, which, for example, in the low-priced motorcycle or moped sector (1-2 cylinders / internal combustion engine) for decades are almost unchanged in series, implement. It is only to be expected with a few constructive changes.

A development of the invention provides that the locking device consists of a spring-loaded ball, wherein the ball engages in a recess in the sliding axis. In this case, the sliding axis for each of its switching positions on such a recess. Thus, the locking device is constructed of simple and inexpensive to manufacture components that have little or almost no wear.

The recess can be made as a transverse bore in the sliding axis. It makes sense, the ball-facing outlet opening of the transverse bore kugelkalotten form, so that the spring-loaded ball can snuggle well into this dome.

A particularly simple adjustment of the sliding axis is achieved in that for the displacement of the sliding axis on the camshaft, a control disc is provided with least a Verschiebenutprofil into which a sliding axis transverse penetrating spring-loaded control pin is inserted, which is movable via a stationary actuator, said the Verschiebenutprofil opposite end of the control pin is guided in a slot.

The sliding groove profile for the control pin is, for example, designed as a DS or XS groove known from large-scale sliding cam valve drives, whereby other groove profiles are also possible. In the case of the cams, more than two cams of different contours are also possible. Thus, three or more cams with mutually different cam profiles can be used. In this case, it must then only be ensured that a switching position and thus a recess in the sliding axis is provided for each cam.

The invention is not limited to the specified combination of the features of independent claim 1 with the claims dependent thereon. In addition, there are further possibilities of combining individual features, in particular if they arise from the patent claims, the following description of the exemplary embodiments or directly from the figures. In addition, the reference of the claims to the figures by the use of reference numerals is not intended to limit the scope of the claims to the illustrated embodiment examples.

Short description of the drawing

For further explanation of the invention reference is made to the drawing, in which a preferred embodiment is shown in simplified form. Show it:

1 a longitudinal section through a cylinder head of a single-cylinder, four-valve internal combustion engine at the level of an intake camshaft with a sliding axis and an actuator for shifting the sliding axis,

2 a cross section at the level of a locking device by a cylinder head with two overhead camshafts and a sliding axis.

Detailed description of the drawing

Out 1 is a variable-stroke DOHC valve train 1 a single cylinder 4V motorcycle internal combustion engine, with only one inlet side shown.

In a cylinder head serving as a housing 2 with three bearings 19 is a longitudinally movable sliding axis 3 arranged. It can be seen that two through a central bearing point 19 separated rocker arms 4 on the sliding axis 3 rotatably mounted, but axially via two retaining rings 21 are fixed.

Each rocker arm 4 One is stuck on a camshaft 5 sitting cam group 6 with a small and large lift cam 7 . 8th assigned. The sliding axis 3 is in 1 drawn in its first switching position (right-hand side). Here are the two necessarily widened rocker arm 4 among the big-stroke cams 8th and act without lateral displacement on their underlying gas exchange valves 24 kippfrei a, more precisely, only their valve springs can be seen. At a second switching position of the sliding axis 3 (left stop) run the two rocker arms 4 under her small-lift cams 7 with offset to the gas exchange valves. The high-lift cams 8th turn empty with respect to a lever area corresponding to the right here.

For shifting the sliding axis 3 in the two switching positions are means 9 provided, which are described below. These include a camshaft-proof, separate control disc 10 with an axial displacement groove profile 11 , which is present here as a DS-groove (double S-slot) and in front of the outer (right) bearing point 19 a sprocket 22 opposite, on the camshaft 5 is fixed. Furthermore, this includes the sliding axis 3 radially penetrating control pin 12 to engage with its one end 13 in the move profile 11 (disengaged and immediately before the beginning of the displacement profile 11 drawn). Besides, one is the control disc 10 on the sliding axis 3 diametrically opposite holding block 14 with an electromagnetic actuator 15 this part of the funds 9 , The holding block 14 is how good 1 recognizable, one-piece with the outer, sprocket side bearing 19 executed.

For example. it is provided in further concretization, form the control disk with the sliding groove as a separate ring as a sheet metal ring and subsequently with the camshaft, for example. To be connected by pressing or shrinking. ever according to available space, the skilled person will find a suitable mounting location on the camshaft here. This can, but need not, be located on the sprocket side at the first bearing point of the housing. Alternatively, the control disk can also be formed integrally with the camshaft or present as a structural module thereof.

A switching pin 16 of the actuator 15 , which only needs to be briefly energized for its extension movement, is in permanent contact with another, as a plate-like widening 20 executed end 17 of the tax pin 12 ,

One the control pin 12 comprehensive spring is designed as a helical compression spring and provides only for a return position of the control pin 12 and the switch pin 16 in the actuator. Thus, an unwanted extension of the pins in gegenlaufendem Steuerut profile and switched off energization of the actuator 15 prevented, which must be briefly energized only for its entry into the Verschiebenutprofil. Otherwise, the control pin over frictional force in the sliding groove profile 11 held. However, it can also be provided to keep the actuator fully energized in the shift mode.

The sliding axis 3 is in the area of the holding block 14 stored. It points there parallel to the sliding axis 3 extending slot 18 on. The slot 18 is designed so that the control pin 12 from one to the other switching position with the sliding axis 3 can be moved without the ends of the slot 18 to initiate. However, the contour of the slot is 18 so dimensioned that they serve as anti-rotation of the control pin 12 and thus the sliding axis 3 can work.

In 2 is a cross section through the cylinder head 2 at the height of a locking device 25 shown. Here are the same components with the same reference numerals as in 1 designated.

Unlike the in 1 purely schematically represented cylinder head 2 is in 2 a real cylinder head shown in cross section. He has two overhead camshaft 5 on. Furthermore, here are the bearings 19 designed in two parts for the camshafts. Further, an inlet and an outlet channel 32 . 33 to see as well as a bore 34 for a centrally located injector. The sliding axis 3 is close to the intake camshaft 5 in the cylinder head 2 stored. The actuator 15 is not visible here.

The locking device 25 consists of a stationary spring 26 on a ball 27 , presses, and a spherical cap 28 at each switching position in the sliding axis 3 , The feather 26 and the ball 27 are a bore 29 in the cylinder head 2 arranged. This bore is closed to the outside by a grub screw 30 , about the same time the tension of the spring 26 can be adjusted and thus the force can be adjusted, the shift in a sliding axis 3 to push out of the ball must be overcome from their calotte.

The spherical cap 28 is located at the ball 27 facing the end of a transverse bore 31 in the sliding axis 3 is introduced. Thus, the shift axis is for each shift position 3 a transverse bore 31 provided with kugelkalottenartigem end in a position such that the ball 27 in the individual switching positions in the respective spherical cap 28 can engage.

LIST OF REFERENCE NUMBERS

1

 valve train

2

 cylinder head

3

 sliding axis

4

 rocker

5

 camshaft

6

 cam group

7

 Kleinhubnocken

8th

 Großhubnocken

9

 medium

10

 control disc

11

 Verschiebenutprofil

12

 control pin

13

an end of 12

14

 holding block

15

 actuator

16

 switch Probe

17

other end of 12

18

 Long hole

19

Depository of 3 and 5

20

 widening

21

 circlip

22

 Sprocket

23

Spring from 12

24

 Gas exchange valve

25

 locking

26

 feather

27

 Bullet

28

 spherical cap

29

Bore in 2

30

 grub screw

31

 cross hole

32

 inlet channel

33

 exhaust port

34

 drilling

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011101871 B1 [0002]

Claims (4)

Variable valve train ( 1 ) for a reciprocating internal combustion engine, with a camshaft ( 5 ), which at least a part of the in a housing, in particular a cylinder head ( 2 ), mounted gas exchange valves ( 24 ) with interposition of a rocker arm ( 4 ), each rocker arm ( 4 ) rotatable but axially secured on a sliding sliding axis arranged in the housing ( 3 ) is mounted, wherein the camshaft ( 5 ) per gas exchange valve ( 24 ) at least two cams ( 7 . 8th ) of different contour and wherein means ( 9 ) for shifting the sliding axis ( 3 ) are provided in at least two switching position, so that each rocker arm ( 4 ) in the first switching position under the first and in the second switching position under the second cam ( 7 . 8th ), characterized in that the sliding axis ( 3 ) in each switching position of a locking device ( 25 ) is held. Variable valve drive according to claim 1, characterized in that the locking device ( 25 ) from a spring-loaded ball ( 27 ), the ball ( 27 ) in a recess in the sliding axis ( 3 ) engages. Variable valve drive according to claim 1 or 2, characterized in that the recess as a transverse bore ( 31 ) in the sliding axis ( 3 ) is executed, whose the ball ( 27 ) facing the outlet opening is formed kugelkalottenartig. Variable valve drive according to one of the preceding claims, characterized in that for the displacement of the sliding axis ( 3 ) on the camshaft ( 5 ) a control disk ( 10 ) with at least one displacement profile ( 11 ), in which a the sliding axis ( 3 ) transversely penetrating spring-loaded control pin ( 12 ) which can be inserted via a stationary actuator ( 15 ) is movable, whereby the the Verschiebenutprofil ( 11 ) opposite end ( 17 ) of the control pin ( 12 ) in a slot ( 18 ) is arranged.

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