DE102011114299B4 - Valve train of an internal combustion engine and method for producing a valve train - Google Patents

Abstract

Valve drive (1) of an internal combustion engine, with at least one basic camshaft (2), on which at least one cam carrier (3) is provided which is rotationally fixed and axially displaceable between at least two axial positions and has at least one valve actuation cam (6,7,8,9), the cam carrier (3 ) for axial displacement by means of an actuator, a shift gate (12) is assigned which has a slide track (13) into which a driver of the actuator can be introduced for moving the cam carrier (3), characterized in that the shift gate (12) consists of a The carrier element (18) and an attachment part (19) fastened to the carrier element (18), the carrier element (18) consisting of a base body (21) and a first functional part (22), the first functional part (22) being the slide track ( 13) and the base body (21) surrounds the cam carrier (3) at least partially in the circumferential direction, the base body (21) having at least one longitudinal groove (25), ie e extends through the base body (21) partially in the axial direction and completely in the radial direction.

Description

The invention relates to a valve drive of an internal combustion engine, with at least one basic camshaft, on which at least one cam carrier having valve actuation cams is provided in a rotationally fixed manner and axially displaceable between at least two axial positions, the cam carrier being assigned a shift gate which has a slide track for axial displacement by means of an actuator, into which a driver of the actuator can be introduced for moving the cam carrier. The invention also relates to a method for producing a valve drive.

Valve drives of the type mentioned are known from the prior art. They are used for internal combustion engines in which the working cycle of gas exchange valves of individual cylinders of the internal combustion engine can be influenced to improve the thermodynamic properties. The at least one cam carrier, which can also be referred to as a cam piece, is arranged on the base camshaft in a rotationally fixed and axially displaceable manner. The cam carrier is usually assigned several, that is to say at least two, valve actuation cams. Each of these valve actuation cams has an eccentricity which is used to actuate one of the gas exchange valves of the internal combustion engine at a specific angle of rotation of the basic camshaft. The valve actuating cams accordingly rotate together with the basic camshaft, so that the respective gas exchange valve of the internal combustion engine is actuated at least once per revolution of the basic camshaft by the associated valve actuating cam or its eccentricity. For this purpose, the valve actuation cam preferably interacts with a roller rocker arm of the gas exchange valve in that it comes into abutment contact with the latter.

A plurality of valve actuation cams are preferably provided which can be assigned to different cam groups. The valve actuation cams of a cam group now differ, for example, with regard to the angular position of their eccentricity or the extent of the same in the radial direction (height) and / or in the circumferential direction (length). By axially displacing the cam carrier, it can be brought into at least two, for example into a first and a second, axial position. In the first axial position the gas exchange valve is actuated by a first of the valve actuation cams and in the second axial position by a second of the valve actuation cams which are assigned to the same group of cams. By displacing the cam carrier, the opening time, the opening duration and / or the stroke of the gas exchange valve can thus be selected, in particular as a function of an operating state of the internal combustion engine.

The cam carrier is displaced or shifted in the axial direction with the aid of an actuating device which comprises a shift gate on the cam carrier and a stationary actuator, usually in a cylinder head of the internal combustion engine. The actuator has an extendable driver which can be brought into engagement with a, for example, screw-shaped or spiral-shaped link path of the shift gate. The slide track is provided on the shift gate which is assigned to the cam carrier. For example, the shift gate is on the cam carrier or is operatively connected to it for axial displacement. The slide track is preferably in the form of a radial groove which extends through the circumference of the shift gate, that is to say is designed with an open edge in it.

The shift gate is usually produced by machining from bar material, the gate track in particular being formed by milling. A time-consuming milling process with at least three traversing is provided for each slide track, with a first side surface (first groove flank) being formed on a first run, a second side surface (second groove flank) on a second run and the groove base of the slide track being formed on a third run. It is often necessary to subject the shift gate to a subsequent heat treatment in order to increase its surface hardness also in the area of the gate tracks. Steel is often used as the material for the shift gate. However, this requires a high weight. For example, from the prior art DE 10 2010 004 591 A1 known, which discloses a cam carrier for a valve train of an internal combustion engine. At least one shift gate is provided on this cam carrier for displacement on a basic camshaft of the valve drive. However, the shift gate has the disadvantages mentioned above.

From the prior art, for example, is the document DE 10 2010 060 766 A1 known. This relates to a sliding cam system for use in a valve drive of an internal combustion engine, with at least one multi-stage sliding cam and a shift gate connected to it. It is provided that the shift gate is formed from two interconnected parts, which are designed as formed sheet metal parts, each part of the shift gate having an edge of an adjustment groove of the shift gate.

It is therefore the object of the invention to propose a valve drive of an internal combustion engine which does not have the disadvantages mentioned at the beginning has, but in particular has a shift gate that is simple and inexpensive to manufacture.

This is achieved according to the invention with a valve drive with the features of claim 1. It is provided that the shift gate consists of a carrier element and an add-on part fastened to the carrier element, the carrier element consisting of a base body and a first functional part, the first functional part also forming the slide track and the base body encompassing the cam carrier at least partially in the circumferential direction, wherein the base body has at least one longitudinal groove which partially extends through the base body in the axial direction and completely in the radial direction. Basically, it is provided that the shift gate consists of a carrier element and at least one add-on part fastened to the carrier element. The shift gate is provided as a built-up shift gate and consists of several individual components, namely the carrier element and the at least one attachment. The individual components are designed in such a way that they can be produced simply and inexpensively and can just as easily be assembled. For example, the individual components are produced using a primary molding process, such as casting or sintering. The carrier element and the attachment are to this extent original molded parts, in particular cast parts or sintered parts. The carrier element and the attachment are preferably made of the same material. This is selected in particular in such a way that no post-treatment, for example hardening, is necessary. A further post-processing step, which is necessary with the shift gate known from the prior art, is thus omitted. Either metal, in particular steel or the like, but also plastic can be used as the material. The use of plastic significantly reduces the weight of the shift gate and is therefore preferable.

The carrier element and the attachment are attached to one another by joining when the valve drive is assembled. The embodiment of the shift gate described above offers the advantage that the individual components can be manufactured by casting, which results in a simpler manufacturing process. Finishing or post-processing is also no longer necessary. In addition to metallic materials, plastics can also be used. The latter preferably have impact-resistant properties or are fiber-reinforced. The described reduction in weight also particularly lowers the component load on the valve drive during the axial displacement of the cam carrier. The manufacturing process that can now be implemented means that a high surface quality can be manufactured simply and inexpensively in the area of the slide track. This applies in particular to the groove flanks of the slide track.

A further development of the invention provides that the slide track is formed jointly by the carrier element and the attachment or several attachment parts. The slide track is therefore only created when the attachment is mounted on the carrier element. If several slide tracks are provided, it may be necessary that several add-on parts have to be attached to the carrier element.

A further development of the invention provides that there is a groove base of the slide track on the carrier element and / or the attachment. The slide track is present as a radial groove which is open at the edge in the shift gate and has a groove base which delimits it inward in the radial direction. The groove base is either only on the carrier element, only on the attachment or on both elements at the same time. In the latter case, it is provided that the groove base begins at one of the elements and then passes over to the other of the elements.

The invention provides that the carrier element consists of a base body and a first functional part, the first functional part also forming the link track and the base body at least partially encompassing the cam carrier in the circumferential direction. The base body and the first functional part are preferably made in one piece and made of the same material, so they are not only brought together when the valve drive is assembled, but are present as a unit immediately after their manufacture. However, they have different functionalities. While the base body serves to hold the shift gate on the cam carrier and for this purpose surrounds it at least in some areas in the circumferential direction, the first functional part at least forms the gate track or has it.

The invention also provides that the base body has at least one longitudinal groove which partially extends through the base body in the axial direction and completely in the radial direction. The longitudinal groove serves to make the base body elastic in the radial direction. In particular, it is provided that when the add-on part is mounted on the carrier element, the base body is urged inward by the add-on part in the radial direction, so that it is subsequently held in a clamping manner on the cam carrier.

A further development of the invention provides that the attachment is attached to the base body and the base body has a support surface for the attachment on its outer circumference, which is in full contact with a support surface of the attachment. The support surface of the base body and the support surface of the attachment accordingly correspond to one another after the valve drive has been installed, in particular in order to prevent the attachment from tilting relative to the base body. For this purpose, the two surfaces are in support contact with one another over their entire surface. The support surface can be penetrated by the longitudinal groove described above, so that when the support contact is established, the base body is deformed inward in the radial direction and its connection to the cam carrier is thus established.

A further development of the invention provides that the base body has at least one anti-rotation element which cooperates with a corresponding counter-anti-rotation element of the attachment. The anti-rotation element and the counter-anti-rotation element form an anti-rotation element. This prevents the attachment from being applied to the base body in the wrong orientation during assembly and from changing the orientation when the valve drive is in operation.

A further development of the invention provides that two add-on parts are provided, one of the add-on parts being present as a separating component and another of the add-on parts being present as a second functional part, the second functional part and the separating component also forming a further link path. There are consequently at least two slide tracks, which are present on the shift gate. For this purpose, there is more than one attachment, in particular two attachment parts. The separating component is located adjacent to the first functional part of the carrier element and the second functional part is located on the side of the separating component facing away from the first functional part. The first functional part and the separating component now form the first slide track. Correspondingly, the further link path is at least also formed by the separating component and the second functional part.

A further development of the invention provides that the slide track has an inlet area and an outlet area and the inlet area is on the functional part and the outlet area is on the separating component. The inlet area is that area of the slide track that is passed through first by the actuator of the actuator.

From the inlet area, it reaches the outlet area directly or indirectly, for example via a reversal area or deflection area. This preferably has a ramp which pushes the driver outward in the radial direction, so that the driver is again out of engagement with the slide track after it has passed through it once.

This means that the driver cannot intervene again in the slide track during a subsequent rotation of the base camshaft or the shift gate, but rather that the axial displacement of the cam carrier is completed after the single run through the slide track. If the cam carrier is to be shifted again, the driver of the actuator must accordingly be shifted inward again in the radial direction so that it comes into engagement with the slide track, in particular the inlet area. It is now provided that the inlet area is at least partially on the functional part and the outlet area is at least partially on the separating component. The driver thus first comes into physical contact with the functional part, that is to say either the first or the second functional part, and then with the separating component.

The invention further relates to a method for producing a valve drive, in particular according to the above statements, the valve drive having at least one base camshaft on which at least one cam carrier having valve actuation cams is provided in a rotationally fixed manner and axially displaceable between at least two axial positions, the cam carrier for axial displacement a shift gate is assigned by means of an actuator, which has a gate track into which a driver of an actuator for moving the cam carrier can be introduced. It is provided that the shift gate is assembled from a carrier element and at least one attachment part fastened to the carrier element during assembly of the valve drive, the carrier element consisting of a base body and a first functional part, the first functional part also forming the gate track and the base body the The cam carrier engages around at least regionally in the circumferential direction, the base body having at least one longitudinal groove which partially extends through the base body in the axial direction and completely in the radial direction. In particular, it is provided that first the carrier element is applied to the shift gate, preferably attached, and then the at least one attachment is attached to the carrier element. In this way, as already described above, the base body of the carrier element can be deformed inward in the radial direction so that a secure connection between the shift gate and the cam carrier is also established by fastening the attachment to the carrier element. In addition, there can of course be an anti-rotation device between the cam carrier and the shift gate, which a Rotation of shift gate and cam carrier against each other prevented.

• 1 einen Bereich eines Ventiltriebs einer Brennkraftmaschine, wobei lediglich ein Nockenträger mit Ventilbetätigungsnocken und einer Schaltkulisse dargestellt ist,
• 2 die Schaltkulisse, bestehend aus einem Trägerelement und mehreren Anbauteilen,
• 3 eine Explosionsdarstellung der Schaltkulisse,
• 4 einen Grundkörper des Trägerelements der Schaltkulisse,
• 5 ein erstes Anbauteil der Schaltkulisse, und
• 6 ein zweites Anbauteil der Schaltkulisse.

The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawing, without restricting the invention. Show:

• 1 an area of a valve drive of an internal combustion engine, only one cam carrier with valve actuation cams and a shift gate being shown,
• 2 the shift gate, consisting of a carrier element and several attachments,
• 3 an exploded view of the shift gate,
• 4th a base body of the carrier element of the shift gate,
• 5 a first attachment part of the shift gate, and
• 6th a second attachment part of the shift gate.

The 1 shows a portion of a valve train 1 an internal combustion engine, not shown. The valve train 1 consists of a basic camshaft 2 and a cam carrier that can be moved axially on this 3 . The axial direction is to be understood as a direction which is parallel to a longitudinal axis, not shown here, of the basic camshaft 2 present. The cam carrier 3 has a central recess 4th on which of the basic camshaft 2 is penetrated. In the area of the recess 4th has the cam carrier 3 via an internal toothing 5 , which with an external toothing, not shown, of the basic camshaft 2 cooperates to the cam carrier 3 non-rotatably but axially displaceable on the base camshaft 2 to keep. The cam carrier 3 has multiple valve actuation cams 6th , 7th , 8th and 9 on, the valve operating cams 6th and 7th a cam group 10 and the valve actuation cams 8th and 9 a cam group 11 assigned. Furthermore, the cam carrier has 3 via a shift gate 12 , which is part of an actuator not shown here. With the help of the adjusting device, the cam carrier is 3 on the base camshaft 2 displaceable in the axial direction.

The valve actuation cams 6th , 7th , 8th and 9 serve to actuate gas exchange valves (not shown) of the internal combustion engine. It can be seen that the valve actuation cams shown here 6th , 7th , 8th and 9 are eccentric, the eccentricities at different angular positions or circumferential positions with respect to the cam carrier 3 exist and / or have different extensions in the radial direction and / or circumferential direction. The valve actuation cams act to actuate the gas exchange valves 6th , 7th , 8th and 9 for example with roller rocker arms of the respective gas exchange valve through system contact. The respective valve actuating cams are for each of the roller rocker arms 6th and 7th respectively 8th and 9 the corresponding cam group 10 or 11 assigned. A first of the roller rocker arms is therefore from the valve actuating cam 6th or 7th and another one of the roller finger followers from the valve operating cam 8th or 9 actuated.

Due to the different design of the valve actuation cams 6th and 7th respectively 8th and 9 A corresponding stroke, opening time and / or opening duration of the gas exchange valve is thus established among one another. By moving the cam carrier axially 3 can the roller rocker arm from the valve actuation cam 6th or 7th respectively 8th or 9 of the respective cam group 10 or 11 be operable. The cam carrier 3 is displaced, for example, as a function of an operating state of the internal combustion engine, so that that valve actuation cam is always the one 6th or 7th with the first roller rocker arm or that valve actuation cam 8th or 9 interacts with the second roller rocker arm for its actuation, with which, for example, an optimal efficiency or an optimal performance of the internal combustion engine can be achieved.

The 2 shows a detailed view of the shift gate 12 . This has two slide tracks 13th and 14th on, in which a driver of an actuator of the adjusting device for moving the shift gate 12 and thus also of the cam carrier 3 can intervene. The scenery tracks 13th and 14th each consist of an inlet area 15th respectively 16 and a common run-out area 17th , which seen in the axial direction between the two inlet areas 15th and 16 present.

The 3 shows an exploded view of the shift gate 12 It becomes clear that this consists of a carrier element 18th as well as two attachments 19th and 20th consists. The carrier element 18th consists of a basic body 21st and a first functional part 22nd together. The basic body 21st essentially serves to accommodate a region of the cam carrier 3 like this in the 1 is shown. The first functional part 22nd forms together with the attachment 19th the backdrop track 13th out. In particular, form the first functional part 22nd and the attachment 19th Groove walls 23 from which the backdrop track 13th at least over an area of the circumference of the shift gate 12 limit. Likewise form the base body 21st and the first functional part 22nd each one area of a groove base 24 the slide track 13th . The same applies to the slide track 14th which of the attachments 19th and 20th is formed in an analogous manner. The attachment 19th is insofar as a separating component 19th and the attachment 20th as a second functional part 20th before, the two functional parts 22nd and 20th are formed substantially symmetrically to one another.

It can be clearly seen that the base body has a longitudinal groove 25th has, which partially extends through it in the axial direction and completely in the radial direction. This longitudinal groove 25th serves to the base body 21st to be flexible in the radial direction, so that it can be achieved by attaching the attachments 19th and 20th in the radial direction inwards and thus onto the cam carrier 3 being pushed. In this way there is a clamp connection between the shift gate 12 and the cam carrier 3 manufactured. Between the carrier element 18th and the attachments 19th and 20th is an anti-twist device 26th intended. This consists of one on the main body 21st provided anti-rotation element 27 , which is essentially present as a radial web extending in the axial direction. The anti-rotation element 27 works with anti-rotation counter elements 28 together, which in the present exemplary embodiment are present as radial grooves extending in the axial direction. The anti-rotation element 27 and the anti-rotation counter element 28 are designed in such a way that the attachments can be pushed on 19th and 20th on the carrier element 18th allow, but fix in the circumferential direction with respect to this rotationally fixed.

The basic body 21st has a bearing surface on its outer circumference 29 on. This occurs when assembling the valve train 1 Support surfaces 30th the attachments 19th and 20th fully in support contact. The support surfaces 30th lie on an inner circumference of the attachments 19th and 20th in front. The support surfaces 29 and the support surfaces 30th are designed in such a way that tilting of the attachments 19th and 20th with respect to the carrier element 18th is prevented. For this purpose, the support surfaces point 30th a certain axial extent. Overall, it becomes clear that the shift gate 12 of several individual components, namely the carrier element 18th and the attachments 19th and 20th is formed. The individual components can be made of the same material or made of different materials. In particular, it is provided that the individual components are produced using a primary molding process, in particular casting or sintering. If production by casting is envisaged, the individual components are designed in such a way that they can be easily removed from a casting mold in the axial direction.

The 4th , 5 and 6th each show alternative views of the carrier element 18th , the attachment 19th and the attachment 20th . In this respect, reference is made to the description above.

List of reference symbols

1

Valve train

2

Basic camshaft

3

Cam carrier

4th

Recess

5

Internal gearing

6th

Valve actuation cam

7th

Valve actuation cam

8th

Valve actuation cam

9

Valve actuation cam

10

Cam group

11

Cam group

12th

Shift gate

13

Slide track

14th

Slide track

15th

Inlet area

16

Inlet area

17th

Run-out area

18th

Support element

19th

Attachment, separating component

20th

Attachment, second functional part

21st

Base body

22nd

First functional part

23

Groove wall

24

Groove base

25th

Longitudinal groove

26th

Anti-twist device

27

Anti-rotation element

28

Anti-rotation counter element

29

Support surface

30th

Support surface

Claims (8)

Valve drive (1) of an internal combustion engine, with at least one basic camshaft (2), on which at least one cam carrier (3) is provided which is rotationally fixed and axially displaceable between at least two axial positions and has at least one valve actuation cam (6,7,8,9), the cam carrier (3 ) for axial displacement by means of an actuator, a shift gate (12) is assigned which has a gate track (13) into which a driver of the actuator can be introduced for moving the cam carrier (3), characterized in that the Shift gate (12) consists of a carrier element (18) and an attachment part (19) attached to the carrier element (18), the carrier element (18) consisting of a base body (21) and a first functional part (22), the first functional part (22) also forms the slide track (13) and the base body (21) surrounds the cam carrier (3) at least partially in the circumferential direction, the base body (21) having at least one longitudinal groove (25) which the base body (21) in the axial direction partially and completely engages in the radial direction. Valve train according to Claim 1 , characterized in that the slide track (13) is formed jointly by the carrier element (18) and the attachment (19). Valve drive according to one of the preceding claims, characterized in that there is a groove base (24) of the slide track (13) on the carrier element (18) and / or the attachment (19). Valve drive according to one of the preceding claims, characterized in that the attachment (19) is attached to the base body (21) and the base body (21) has a support surface (29) on its outer circumference for the attachment (19), which has a support surface (30) of the attachment (19) is in support contact over the entire surface. Valve drive according to one of the preceding claims, characterized in that the base body (21) has at least one anti-rotation element (27) which interacts with a corresponding counter-anti-rotation element (28) of the attachment (19). Valve drive according to one of the preceding claims, characterized in that, in addition to the attachment (19), a further attachment (20) is provided, the attachment (19) as a separating component (19) and the additional attachment (20) as a second functional part (20) ) is present, the second functional part (20) and the separating component (19) also forming a further link path (14). Valve train according to Claim 6 , characterized in that the slide track (13) has an inlet area (15) and an outlet area (17) and the inlet area (15) is on the first functional part (22) and the outlet area (17) is on the separating component (19). A method for producing a valve drive (1) which has at least one basic camshaft (2) on which at least one cam carrier (3) is provided which is rotationally fixed and axially displaceable between at least two axial positions and has at least one valve-actuating cam (6,7,8,9), wherein the cam carrier (3) is assigned a shift gate (12) for axial displacement by means of an actuator, which has a gate track (13) into which a driver of the actuator can be inserted for moving the cam carrier (3), characterized in that the shift gate ( 12) when assembling the valve drive (1) from a carrier element (18) and at least one add-on part (19, 20) attached to the carrier element (18), the carrier element (18) being composed of a base body (21) and a first Functional part (22), the first functional part (22) also forming the link path (13) and the base body (21) at least in the circumferential direction the cam carrier (3) s way around, the base body (21) having at least one longitudinal groove (25) which extends through the base body (21) partially in the axial direction and completely in the radial direction.

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