Valve train for an internal combustion engine as well as internal combustion engine
The valve train design allows for easy and reliable adjustment of valve lifts and opening times in internal combustion engines by using a camshaft with a link section and actuator, addressing the complexity and reliability issues of existing systems.
Patent Information
- Application Number
- DE102013111410
- Authority / Receiving Office
- DE · DE
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2013-10-16
- Publication Date
- 2024-12-24
- Estimated Expiration
- 2033-10-16
AI Technical Summary
Existing valve trains for internal combustion engines lack a simple and reliable mechanism to achieve variable valve lifts and opening times using the desmodromic principle, as they often require complex actuation systems or unreliable locking mechanisms.
A valve train design featuring a camshaft with a link section and grooves on its outer surface, actuated by a cooperating mechanism, allowing axial displacement and reliable locking of the camshaft position, enabling variable valve lifts and opening times through interaction with a locking ball and spring element.
Enables easy and reliable adjustment of valve lifts and opening times by axially displacing the camshaft, providing a simple and effective variable valve drive based on the desmodromic principle.
Smart Images
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Abstract
Description
[0001] The invention relates to a valve train for an internal combustion engine according to the preamble of claim 1 and an internal combustion engine with such a valve train.
[0002] In internal combustion engines, variable valve trains are used to optimise the charge movement in the combustion chamber, with which different valve lifts can be set in particular on the gas exchange valves of the internal combustion engine.
[0003] A valve train according to the desmodromic principle for an internal combustion engine according to the preamble of claim 1 is known from EP 0 384 361 B1. Thus, the valve train known from this prior art comprises at least one rotatably mounted camshaft, wherein the or each camshaft has first cams serving as opening cams for opening gas exchange valves of the internal combustion engine, and second cams designed as closing cams for closing the gas exchange valves of the internal combustion engine. The opening cams act on a valve stem of a gas exchange valve via opening rocker arms, and the closing cams act on a valve stem of a gas exchange valve via closing rocker arms, namely in such a way that the opening rocker arms acted by the first cams or the opening cams act on the respective gas exchange valve in the opening direction, and the closing rocker arms acted by the second cams or closing cams act on the respective gas exchange valve in the closing direction.
[0004] Furthermore, it is known from EP 0 384 361 B1 that the first cams or opening cams and the second cams or closing cams have different cam tracks in order to provide a variable valve train with which different valve lifts and different valve opening times can be provided.
[0005] US 5,129,407 A discloses a valve train for an internal combustion engine, wherein the camshaft is mounted in bearings, and wherein a camshaft guide portion with a groove formed on an outer circumferential surface is provided at one end of the camshaft. An actuator cooperating with the camshaft guide portion is provided to effect axial displacement of the camshaft together with the cams.
[0006] DE 101 55 007 A1 discloses a valve train for an engine, which has a rotatably mounted camshaft for actuating gas exchange valves, wherein the camshaft carries first cams which serve to open gas exchange valves, and second cams which serve to close the gas exchange valves.
[0007] DE 10 2008 035 935 A1 and DE 10 2011 101400 A1 each disclose cam pieces mounted axially movably on carrier shafts.
[0008] Based on this, the present invention is based on the object of creating a novel valve train for an internal combustion engine and an internal combustion engine with such a valve train.
[0009] This object is achieved by a valve train for an internal combustion engine according to claim 1.
[0010] Ends of the respective axially displaceable camshafts are guided in bearings. According to the invention, the or each camshaft has a guide section arranged between the bearings arranged at opposite ends of the camshaft, with at least one groove formed on an outer circumferential surface of the respective guide section. An actuator cooperating with the guide section is provided to effect an axial displacement of the respective camshaft together with the cams thereof, and the respective camshaft can be locked in its axial relative position after an axial displacement.
[0011] The present invention proposes a valve train based on the desmodromic principle for an internal combustion engine, wherein the or each camshaft of the valve train, together with the cams thereof, can be displaced simply and reliably in the axial direction, namely via a link section that interacts with an actuator to displace the camshaft in the axial direction to change the valve lift and / or the valve opening times of gas exchange valves of the internal combustion engine. Furthermore, the respective camshaft can be locked in its axial relative position. Such a design allows the provision of a simple and reliable, variable valve train based on the desmodromic principle.
[0012] Each first cam has different cam tracks, with one of the cam tracks of each first cam actuating the respective gas exchange valve to open depending on the axial relative position of the camshaft. Each second cam also has different cam tracks, with one of the cam tracks of each second cam actuating the respective gas exchange valve to close depending on the axial relative position of the camshaft. This allows different valve lifts and / or valve opening times to be provided easily and reliably.
[0013] As already explained, the ends of the respective axially displaceable camshafts are guided in bearings, with a locking ball acted upon by a spring element being integrated into one end of the respective axially displaceable camshaft as a locking element, which interacts with a contour of a bearing piece enclosing this end of the respective camshaft to lock the axial relative position of the respective axially displaceable camshaft. The spring element presses the locking ball of the respective axially displaceable camshaft outwards into one of several grooves in the contour of the bearing piece, depending on the axial relative position of the same. This design allows for simple and reliable locking of the respective camshaft in its axial relative position.
[0014] Preferably, the first cams, the second cams, and the cam follower section are integral components of the respective camshaft. This design is simple and reliable.
[0015] The internal combustion engine according to the invention is defined in claim 6.
[0016] Preferred developments of the invention will become apparent from the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail, without being limited thereto, with reference to the drawings. Herein: Fig. 1 a partially exploded view of an internal combustion engine with a valve train according to the invention; Fig. 2 a detail of the Fig. 1; Fig. 3 is a cross-section showing a valve train according to the invention in a first state thereof; and Fig. 4 a cross-section showing the valve train according to the invention of Fig. 3 in a second state of the same.
[0017] Fig. 1 shows a partially exploded view of an internal combustion engine with a valve train according to the invention based on the desmodromic principle. Fig. The camshaft 1 of the valve train shown in Figure 1 is mounted via bearings 3 in a camshaft housing 2 of the internal combustion engine. Fig. The camshaft 1 shown in Figure 1 is designed as an intake camshaft and serves to control the intake valves of the internal combustion engine. Of the intake valves, Fig. 1 Valve tappet 4, valve plate 5, and engagement elements 6 and 7 for rocker arms 8 and 9 of the valve train are shown. An exhaust camshaft (not shown) is provided to control the exhaust valves of the internal combustion engine. The intake and exhaust valves are gas exchange valves of the internal combustion engine.
[0018] The Fig. The camshaft 1 shown in Fig. 1 comprises first cams 10, which serve to open the intake valves, and second cams 11, which serve to close the intake valves, wherein the first cams 10 are also referred to as opening cams and the second cams 11 are also referred to as closing cams.
[0019] The first cams 10 act via the rocker arms 9 and the engagement elements 7 on the valve tappets 4 of the intake valves in the opening direction, whereas the second cams 11 act via the rocker arms 8 and the engagement elements 6 on the valve tappets 4 of the intake valves in the closing direction thereof.
[0020] To provide a variable valve train with which different valve lifts and preferably different valve opening times can be provided, each first cam 10, which serves as an opening cam, comprises different cam tracks 12, 13. Every second cam 11 also has such different cam tracks 14, 15.
[0021] The entire camshaft 1 is axially displaceable together with the first cams 10 and the second cams 11 in order to adjust an axial relative position of the camshaft 1 and thus of the cams 10, 11 to the intake valves or the rocker arms 8, 9 interacting with the cams 10, 11.
[0022] The Fig. 3 and Fig. 4 show the camshaft 1 of the valve train in different relative positions, in particular the relative position of the first cams 10 serving as opening cams to the rocker arms 9 serving to actuate the respective intake valve.
[0023] In the relative position of the Fig. 3, in which the camshaft 1 is shifted to the right, the rocker arms 9 are in engagement with the cam tracks 12 of the first cams 10. In the relative position of the Fig. 4, however, in which the camshaft 1 is shifted to the left, the rocker arms 9 are in engagement with the cam tracks 13 of the first cams 10.
[0024] Likewise, the relative position of the cam tracks 14, 15 of the second cam 11 serving as closing cams to the rocker arms 8 changes during the axial displacement of the camshaft 1, but this is in Fig. 3 and Fig. 4 not shown to ensure a clear presentation.
[0025] In order to enable the axial displacement of the respective camshaft 1 of the valve train in a simple and reliable manner, the respective camshaft 1 has a link section 16 with at least one groove 17 formed on an outer surface thereof.
[0026] An actuator 18 interacts with the link section 16, namely the groove 17 thereof, wherein the actuator 18 has at least one actuating pin which can be inserted into the groove 17 in the link section 16 in the radial direction in order to axially displace the entire camshaft 1 including its cams 10, 11.
[0027] The first cams 10, the second cams 11 and the cam section 16 are an integral part of the respective camshaft 1.
[0028] The respective camshaft 1 can be locked in its axial relative position after being axially displaced. Thus, a locking element comprising a locking ball 22 acted upon by a spring element 21 is integrated into one end 19 of the camshaft 1, which is mounted on the camshaft housing 2 via a bearing piece 20 and a bearing 3. The locking element comprises a locking ball 22 acted upon by a spring element 21. The spring element 21 tends to radially push the locking ball 22 out of a bore in which the spring element 21 and the locking ball 22 are received in the end 19 of the camshaft 1.
[0029] The locking element, namely the locking ball 22 thereof, interacts with a contour 23 of the bearing piece 20, wherein this contour 23 of the bearing piece 20, viewed in the axial direction, provides several grooves 24 into which the locking ball 22 of the locking element can be pressed depending on the axial relative position of the camshaft 1. Fig. 3 and Fig. 4, that in order to lock the axial relative position of the camshaft 1, the locking ball 22 of the locking element engages in different grooves 24 of the contour 23 of the bearing piece 20.
[0030] The rotary or rotating drive of the Fig. The camshaft 1 shown in Figures 1 to 4 is engaged via a gear 25, which engages the camshaft 1 via an intermediate piece 26. When a pin of the actuator 18 is inserted into a groove 17 of the camshaft section 16, the rotating movement of the camshaft 1 can be converted into an axial displacement of the same. The bearings 3 of the camshaft 1 allow this axial displacement of the camshaft 1. The locking of the camshaft 1 is achieved through the interaction of the locking ball 22 and the grooves 24.
[0031] The present invention therefore provides a variable valve train based on the desmodromic principle, in which the respective camshaft 1 can be reliably and easily axially displaced, namely together with the cams 10, 11 thereof, in order to set different valve lifts and / or opening times on the respective gas exchange valves to be actuated, depending on the axial relative position of the camshaft 1. The axial displacement of the camshaft 1 is achieved by the interaction of a link section 16 with an actuator 18, wherein the link section 16 has at least one groove 17 into which an actuating pin of the actuator 18 can be inserted for the axial displacement of the respective camshaft 1.
[0032] After the axial displacement of the respective camshaft 1, the same can be locked in its axial relative position by the interaction of the locking element and the bearing piece 20.
[0033] The width of the cams 10, 11 is dimensioned such that the rocker arms 7, 8 engage with the respective cam 10, 11 in all axial relative positions of the camshaft 1, namely with a cam track 12, 13 or 14, 15 of the respective cam 10 or 11 adapted to the valve opening time to be set and / or to the valve lift to be set.
Claims
[1] Valve train for an internal combustion engine according to the desmodromic principle, which has at least one rotatably mounted camshaft (1) for actuating gas exchange valves, wherein the or each camshaft (1) carries first cams (10) which serve to open gas exchange valves, and second cams (11) which serve to close the gas exchange valves, wherein each first cam (10) has different cam tracks (12, 13), wherein one of the cam tracks (12, 13) of each first cam (10) actuates the respective gas exchange valve to open depending on the axial relative position of the respective camshaft (1), wherein each second cam (11) has different cam tracks (14, 15), wherein one of the cam tracks (14, 15) of each second cam (11) actuates the respective gas exchange valve to close depending on the axial relative position of the respective camshaft (1), characterized by , that opposite ends of the respective axially displaceable camshaft (1) are guided in bearings (3), the respective camshaft (1) has a link section (16) arranged between the bearings (3) arranged at the opposite ends of the camshaft (1) with at least one groove (17) formed on an outer surface of the respective link section (16), to effect an axial displacement of the respective camshaft (1) together with the cams (10, 11) thereof, an actuator (18) cooperating with the link section (16) is provided, the respective camshaft (1) can be locked in its axial relative position after an axial displacement, a locking ball (22) acted upon by a spring element (21) is integrated into one end (19) of the respective axially displaceable camshaft (1) as a locking element, which ball cooperates with a contour (23) of a bearing piece (20) enclosing this end (19) of the respective camshaft (1) to lock the axial relative position of the respective axially displaceable camshaft (1), the spring element (21) presses the locking ball (22) of the respective axially displaceable camshaft (1) outwards into one of several grooves (24) of the contour (23) of the bearing piece (20) depending on the axial relative position of the same. [2] Valve train according to claim 1, characterized by that the first cams (10) act on the gas exchange valves via first levers (9) in the opening direction and the second cams (11) act on the gas exchange valves via second levers (8) in the closing direction. [3] Valve train according to claim 1 or 2, characterized bythat the first cams (10), the second cams (11) and the link section (16) are an integral part of the respective camshaft (1). [4] Valve train according to one of claims 1 to 3, characterized by that the actuator (8) has at least one pin which can be displaced in the radial direction. [5] Valve train according to claim 4, characterized by that the respective pin for axial displacement of the respective camshaft (1) can be radially inserted into a respective groove (17) of the link section (16). [6] Internal combustion engine with several cylinders, characterized by that it has a valve train according to one of claims 1 to 5 for actuating gas exchange valves of the cylinders.