Valve train for an internal combustion engine
阅读说明:本技术 用于内燃机的气门机构 (Valve train for an internal combustion engine ) 是由 G·艾默斯伯格 D·克诺尔 R·克拉夫特 R·施密德 T·施泰因勒 于 2018-07-13 设计创作,主要内容包括:本发明涉及一种用于内燃机气缸盖的气门机构,包括可旋转地支承在第一和第二凸轮轴轴承中的第一凸轮轴,该第一凸轮轴包括至少一个具有第一凸轮曲面和不同于第一凸轮曲面的第二凸轮曲面的凸轮,可通过第一或第二凸轮曲面操作换气阀,设置凸轮轴区段,借助该凸轮轴区段可通过执行机构这样移动凸轮,使得可通过第一或第二凸轮曲面操作换气阀,所述第一凸轮轴和凸轮具有彼此固定的位置并且第一凸轮轴可在第一和第二凸轮轴轴承中轴向移动,为凸轮轴设置轴向锁止装置。与现有技术相比,通过根据本发明的气门机构实现了生产成本的显著降低并且避免了不必要的啮合噪音。另外,凸轮轴根据哪个凸轮曲面与换气阀配合作用而轴向锁止。(The invention relates to a valve train for a cylinder head of an internal combustion engine, comprising a first camshaft which is mounted rotatably in a first and a second camshaft bearing and which comprises at least one cam having a first cam curve and a second cam curve different from the first cam curve, gas exchange valves being operable via the first or the second cam curve, a camshaft section being provided, by means of which the cam can be moved by means of an actuator in such a way that the gas exchange valves can be operated via the first or the second cam curve, the first camshaft and the cam having a fixed position relative to one another and the first camshaft being axially movable in the first and the second camshaft bearing, an axial locking device being provided for the camshaft. Compared to the prior art, a significant reduction in production costs and the avoidance of unnecessary meshing noises is achieved by the valve drive according to the invention. In addition, the camshaft is axially locked depending on which cam curve cooperates with the gas exchange valve.)
1. A valve train (1) for a cylinder head of an internal combustion engine, comprising a first camshaft (4) rotatably mounted in a first camshaft bearing (2) and a second camshaft bearing (3), comprising at least one cam (5) having a first cam curve (6) and a second cam curve (7) different from the first cam curve (6), gas exchange valves being operable via the first or second cam curve (6, 7), a camshaft section (8) being provided by means of which the cam (5) can be moved by an actuator (9) such that the gas exchange valves can be operated via the first or second cam curve (6, 7),
characterized in that the first camshaft (4) and the cam (5) have a fixed position relative to each other and the first camshaft (4) is axially displaceable in a first and a second camshaft bearing (2, 3), an axial locking device (10) being provided for the camshaft (4).
2. A valve train as claimed in claim 1, characterized in that the axial locking device (10) has a gate (11) which is radially wound around the camshaft (4) and which has a first and a second gate track (12, 13) which are axially adjacent to one another and in which locking elements (15) which are prestressed by means of spring elements (14) engage.
3. A valve train according to claim 1 or 2, characterized in that the first and second runner tracks (12, 13) are spaced apart from each other by a cylindrical section (24).
4. A valve train according to any of claims 2 or 3, characterized in that the first and second gate tracks (12, 13) form a relative angle α of between 2 ° and 45 ° with the camshaft axis (16), respectively.
5. A valve train according to any one of claims 2 to 4, characterized in that the slide groove (11) is roll-or slide-mounted on the camshaft (4).
6. A valve train according to any of claims 2 to 5, characterized in that the chute (11) has axial grooves on the chute tracks (12, 13) and the cylindrical section (24).
Technical Field
The invention relates to a valve drive for a cylinder head of an internal combustion engine having the features of the preamble of claim 1.
Background
See for example european patent application EP 0595060 a1 for background. From this patent application, a valve drive of an internal combustion engine is known, which has a pretensioned sliding cam that can be moved axially on a camshaft. The sliding cam in the first position can be moved into a second position, in which the sliding cam acts on the intake valve with a first lift profile (Erhebungskurve) and in which the sliding cam acts on the intake valve with a second lift profile. In the first position, the sliding cam bears in a form-fitting manner against a stop of a transmission element connected between the intake valve and the sliding cam, provided that the sliding cam rotates in the stop region by one segment. Upon reaching the base circle of the sliding cam, the sliding cam moves into the second position.
Another example of a sliding cam is known, for example, from german patent application DE 102005006489 a 1. This is a camshaft assembly comprising a base shaft and an axially displaceable but non-rotatably held cam carrier arranged thereon. Cams with a plurality of cam curves are formed on the cam carrier, each cam having a common base circle and different cam curves with different curve profiles from one another. The valve operating devices of the associated cylinders are operated by cams. An actuator is provided for executing a switching process in which the other cam curve of the cam is brought into contact with the valve operating device by axial displacement of the cam carrier on the base shaft.
DE 102004022833 a1 discloses another valve train for an internal combustion engine. The valve mechanism comprises a camshaft with a sliding cam arrangement comprising cam tracks of adjacent cams acting on the valves, which cam tracks have different cam shapes and lift profiles which cooperate with an operating element with a control pin for adjusting the sliding cam arrangement.
Furthermore, reference is made to German patent DE 102009057633B 3. From this patent, a method for producing a combined camshaft, a camshaft basic body and a combined camshaft are known. This patent protects a method for producing a built-up camshaft having at least one cam element arranged on a camshaft base body in a rotationally fixed but axially displaceable manner and at least one cam element arranged on a camshaft base body in a rotationally fixed and axially displaceable manner, comprising the following method steps:
-providing a rod-shaped camshaft base body,
-machining the camshaft base body by:
-surface machining the camshaft basic body in at least one first axial partial section by providing an axially extending outer surface contour,
-the camshaft basic body is surface-machined in at least one second axial partial section, seen in the predetermined threading direction, downstream of the first partial section, by at least regionally enlarging the camshaft basic body to an enlarged outer diameter,
providing a plurality of cam elements having a hub cross section and an inner surface contour extending in the axial direction and correlating with the outer surface contour of the camshaft base body, the smallest inner diameter of the hub cross section being smaller than the largest outer diameter in the second partial section of the camshaft base body;
-mounting a cam element, wherein
The at least one first cam element is inserted onto the camshaft body in the running-in direction beyond the at least one first axial partial section until in front of the enlarged region of the at least one second axial partial section, the inserted cam element being oriented at a precise angle relative to a predetermined reference position of the camshaft base body and being connected to the camshaft base body in a force-fitting manner by a subsequent axial relative movement between the cam element and the camshaft base body, and the camshaft base body is subsequently connected to the camshaft base body in a force-fitting manner, and the at least one first cam element is then inserted into the camshaft base
The at least one second cam element is inserted onto the camshaft base body in the threading direction in an angle-precise manner up to the at least one first partial section and is positioned in a rotationally fixed but axially displaceable manner there.
A disadvantage of the above-described valve train is its complex and expensive production and disturbing acoustic effects based on axial meshing with tolerances during operation of the internal combustion engine.
Disclosure of Invention
The object of the invention is to avoid the disadvantages mentioned above. Another object of the invention is to prevent axial displacement of the camshaft during operation of the internal combustion engine.
This object is achieved by the characterizing features of patent claim 1.
Advantageous embodiments of the invention are specified in the dependent claims.
Due to the integral, axially displaceable camshaft, the production costs are greatly reduced and acoustic problems are avoided because of the lack of axial engagement. Furthermore, the axial locking device proposed makes it possible to minimize the relative movement of the camshaft and the actuator that occurs during operation of the internal combustion engine.
An embodiment of the axial locking device according to claim 2 is a preferred embodiment.
A simple switching of the camshaft and simultaneous locking thereof in the end position can be achieved by means of the embodiment according to claim 3.
The angular range according to
The friction is minimized by means of the embodiment according to
The switching process is significantly simplified and wear is minimized by means of the embodiment according to claim 6.
Drawings
The invention is explained in detail below with reference to embodiments in the five drawings. The attached drawings are as follows:
FIG. 1 shows a top view of a valve train according to the present invention;
fig. 2 shows a plan view of a valve train according to the invention with an axial locking device;
FIG. 3 shows a cross-sectional view of the locking element of the axial locking device;
FIG. 4 shows a cross-sectional view of the axial locking device;
fig. 5 shows a sectional view of a locking element in operative connection with an axial locking device.
Detailed Description
In the following, the same reference numerals are used for the same components in fig. 1 to 5.
Fig. 1 shows a plan view of a valve drive 1 according to the invention for a cylinder head of an internal combustion engine. The cylinder head, which is not labeled, is shown without a valve cover, so that the valve mechanism 1 can be seen. The valve drive 1 is arranged on the intake side and for two cylinders, and has four identically acting gas exchange valves, which are shown in fig. 2.
The valve train 1 according to the invention has a
Furthermore, a camshaft section 8 is provided, into which a non-visible pin of the actuator 9 engages by means of a radially outwardly encircling control groove, so that the
The
In order to reduce the load on the pins of the actuator 9 during operation of the internal combustion engine, according to the invention, an
Fig. 2 shows a plan view of the
Fig. 3 shows a sectional view of the
Fig. 4 shows a sectional view of an
Fig. 5 shows a sectional view of the locking
In a further particularly preferred embodiment, the
The resulting relative movement of the
List of reference numerals
1 valve mechanism
2 first camshaft bearing
3 second camshaft bearing
4 first camshaft
5 cam
6 first cam curved surface
7 second cam curve
8 camshaft section
9 actuator
10 axial locking device
11 chute
12 first chute track
13 second chute track
14 spring element
15 locking element
16 camshaft axis
17 spur gear
18 screw thread connecting piece
19 scavenging valve
20 valve spring
21 bow member
22-cap nut
23 mounting hole
24 cylindrical section
25 rolling bearing
26 travel path
α angle between camshaft axis and chute track
β angle between chute rails
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