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·埃默斯伯格 D·克诺尔 R·克拉夫特 R·施密德 T·施泰因勒 于 2018-07-12 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,其包括可旋转地支承在第一和第二凸轮轴轴承中的凸轮轴,该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轴曲线的凸轮,通过第一或第二凸轮曲面可经由凸轮从动件操作换气阀,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经由凸轮从动件操作换气阀,所述凸轮轴和凸轮具有彼此固定的位置并且凸轮轴可在第一和第二凸轮轴轴承中轴向移动,所述凸轮轴轴承分别包括凸轮轴轴承座和一个共同的轴承架并且设有润滑剂供应孔,该润滑剂供应孔通入轴承架中的第四润滑剂槽,用于向轴承部位供应润滑剂,在第一凸轮轴轴承座中设有第一润滑剂槽并且在第二凸轮轴轴承座中设有第二润滑剂槽,它们与第四润滑剂槽相对应并且朝向凸轮从动件方向敞开。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。此外,凸轮从动件有利地被间断地润滑。(The invention relates to a valve train for a cylinder head of an internal combustion engine, comprising a camshaft which is rotatably mounted in a first and a second camshaft bearing, which camshaft comprises at least one cam having a first cam curve and a second cam curve different from the first cam curve, by means of which first or second cam curve gas exchange valves can be operated via a cam follower, 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 cam follower by means of the first or second cam curve, the camshaft and the cam having a fixed position relative to one another and the camshaft being axially movable in the first and second camshaft bearing, which camshaft bearings each comprise a bearing block and a common bearing carrier and are provided with a lubricant supply bore which opens into a fourth lubricant groove in the bearing carrier, for supplying lubricant to the bearing points, a first lubricant groove is provided in the first camshaft bearing block and a second lubricant groove is provided in the second camshaft bearing block, which grooves correspond to the fourth lubricant groove and open toward the cam follower. 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. Furthermore, the cam follower is advantageously lubricated intermittently.)

1. Valve train for a cylinder head (1) of an internal combustion engine, comprising a 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), by means of which first or second cam curve (6, 7) gas exchange valves can be operated via a cam follower, a camshaft section (8) being provided, by means of which camshaft section the cam (5) can be moved by an actuator such that gas exchange valves can be operated via a cam follower by means of the first or second cam curve (6, 7), characterized in that the camshaft (4) and the cam (5) have a fixed position relative to one another and in that the camshaft (4) can be moved between the first and second camshaft bearing (2, 2), 3) And the camshaft bearings (2, 3) comprise in each case one camshaft bearing block (2', 3') and one common bearing carrier (13), and are provided with a lubricant supply opening (16) which opens into a fourth lubricant groove (14) in the bearing carrier (13) for supplying lubricant to the bearing points, a first lubricant groove (10) being provided in the first camshaft bearing block (2') and a second lubricant groove (11) being provided in the second camshaft bearing block (3'), which correspond to the fourth lubricant groove (14) and open in the direction of the cam follower.

2. A valve train as claimed in claim 1, characterized in that the fourth lubricant groove (14) has a branching (9) at the transition to the camshaft bearing block (2', 3'), and the camshaft bearing block (2', 3') has a corresponding third lubricant groove (12) which is spaced apart from the second lubricant groove (11) by the displacement stroke of the camshaft (4) and opens out in the direction of the cam follower.

3. A valve train according to claim 1 or 2, characterized in that the camshaft (4) has a fifth lubricant groove (15) which surrounds at least in sections radially on the outside and which corresponds to the second or third lubricant groove (11, 12) depending on the position of the camshaft (4).

4. A valve train as claimed in any one of claims 1 to 3, wherein the cam follower is a sliding drag lever.

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

For background reference is made, for example, to the German published patent application DE 102014220385A 1. From this patent application, a switchable valve train of a reciprocating piston internal combustion engine is known, which comprises at least one lever-like cam follower which is rotatably arranged on a lever shaft and can be moved in the axial direction of the lever shaft. The lever shaft is arranged in the camshaft bearing housing extending parallel to the camshaft. The cam follower cooperating with the valve stem end of the gas exchange valve can be at least indirectly in contact with different cam profiles of at least two cams which are part of at least one cam assembly. The at least one cam follower is fixed in the axial direction in a lever shaft which is arranged in the camshaft bearing housing so as to be displaceable in the longitudinal direction and at least one driver arranged on the lever shaft can engage at least one control contour arranged on the camshaft, which extends obliquely or in a curved manner in the direction of a transverse plane of the camshaft. Since the two rocker arms have to perform a rotational movement relative to the lever shaft, which is caused by the cam or cam arrangement, lubricating oil bores are provided in these rocker arms for merging engine oil into the respective sliding bearings of the rocker arms.

A disadvantage of this known embodiment is the very complicated structural arrangement for the sliding movement of the cam follower.

Furthermore, german patent DE 19611641C 1 discloses a valve drive for an internal combustion engine, having a camshaft with cams for actuating gas exchange valves, wherein at least one cam is provided with a plurality of cam tracks arranged axially one behind the other and is guided on the camshaft in a rotationally fixed but axially displaceable manner and is provided with a lift profile (Hubprofil) acting in the axial direction of the camshaft, which lift profile cooperates with at least one actuating element in order to move the cam axially. The lift contour is formed on the cam and the actuating element has an actuating pin arranged radially to the camshaft, which actuating pin engages or disengages the lift contour in a radially displaceable manner.

Such a valve train of an internal combustion engine allows gas exchange valves to be operated with at least two different lift curves. For this purpose, a cam with a plurality of cam tracks is mounted on the camshaft in a rotationally fixed but axially displaceable manner. The cam has a lift profile, in which the operating device engages and thus moves the cam axially, the switching from one cam track to the other cam track being carried out in the axial direction.

A disadvantage of the known system is that a rolling drag rod (rollenschlephebel) is used to operate the gas exchange valve. However, the rolling tow bar is relatively expensive and rolling bearings can be problematic at high rotational speeds, such as in motorcycle engines.

In order to overcome this disadvantage, a valve drive for an internal combustion engine is proposed in german patent application DE 102016200325 a1, on which the invention is based, having a camshaft with a cavity in the axial direction, which has a cam body for actuating at least one gas exchange valve, which has at least one first and one second axially adjacent cam track with different gas exchange valve lift tracks and is arranged radially in a rotationally fixed but axially displaceable manner around the camshaft, the lift adjustment of the gas exchange valve being effected indirectly via a sliding drag lever (gleitschlephebel). The sliding tow bar is much more robust than the rolling tow bar at very high rotational speeds of the internal combustion engine. The camshaft is rotatably mounted in a camshaft bearing and can be filled with lubricant via a lubricant opening in the camshaft bearing and a first passage in the camshaft and a second passage in the cam body, a third passage being provided in the direction of rotation of the camshaft before a cam disk in the camshaft and a fourth passage being provided in the cam body for discharging lubricant from the cavity in order to intermittently lubricate the sliding drag lever.

Intermittent lubrication is used to specifically lubricate the valve actuating device in a volume-flow-saving manner. The oil is applied only during valve operation and then no longer applied. The sliding cam system cannot ensure reliable oil supply. Furthermore, complex machining is required in the sliding cam system and the highest tolerances need to be maintained in order to avoid disturbing noise during the operation of the internal combustion engine.

Disclosure of Invention

The object of the present invention is to provide a measure which avoids the disadvantages described above.

This object is achieved according to the invention by the characterizing features of claim 1.

Advantageous embodiments of the invention are specified in the dependent claims.

The lubrication of the cam followers, for example of the sliding rocker, is achieved by the embodiment of the valve train according to the invention for the camshaft, which is axially displaceable as a whole.

The embodiment according to claim 2 allows the cam follower to be lubricated irrespective of the position of the camshaft.

The embodiment according to claim 3 allows lubricant-saving intermittent lubrication of the cam follower.

It is particularly preferred that the cam follower is a sliding drag lever according to claim 4.

Drawings

The invention is explained in detail below with reference to the four figures.

FIG. 1 shows a top view of a cylinder head without a cylinder head cover;

FIG. 2 illustrates a bottom view of the bearing frame;

FIG. 3 shows a camshaft shown in three dimensions;

fig. 4 shows a sectional view of a camshaft.

Detailed Description

Fig. 1 shows a top view of a cylinder head 1 of an internal combustion engine without a valve cover and a bearing cover, which is formed by a bearing bracket 13 shown in fig. 2. The valve train has a camshaft 4 which is rotatably mounted in a first camshaft bearing 2 and a second camshaft bearing 3 and which, as shown in fig. 4, comprises at least one cam 5 which has a first cam curve 6 and a second cam curve 7 which is different from the first cam curve 6. In this case, a gas exchange valve, not shown, can be actuated by the first or second cam curve 6, 7 via a cam follower, not shown. In the present exemplary embodiment, the camshaft 4 is provided with two gas exchange valves for a single cylinder of the internal combustion engine. Furthermore, a camshaft section 8, which is shown in fig. 4, is provided, by means of which an actuator, not shown, can displace the cam 5 by means of a pin in such a way that the gas exchange valves can be operated by means of the first or second cam curve 6, 7 via a cam follower.

According to the invention, the camshaft 4 and the cam 5 have a fixed position relative to each other and the camshaft 4 is axially movable in the first and second camshaft bearings 2, 3. Furthermore, the camshaft bearings 2, 3 each comprise a camshaft bearing block 2', 3' and a common bearing block 13, which is shown in fig. 2, in the cylinder head 1 a lubricant supply bore 16 is provided, which opens into a fourth lubricant groove 14 in the bearing block 13 for supplying lubricant to the bearing points, in the first camshaft bearing block 2 'a first lubricant groove 10 is provided and in the second camshaft bearing block 3' a second lubricant groove 11 is provided, which corresponds to the fourth lubricant groove 14 and opens in the direction of the cam follower for supplying lubricant to the cam follower. Furthermore, a third lubricant groove 12 is provided in the second bearing block 3' parallel to the second lubricant groove 11, which is also open toward the cam follower to lubricate the cam follower. The distance between the second lubricant groove 11 and the third lubricant groove 12 corresponds to the travel of the camshaft 4 from the first cam curved surface 6 to the second cam curved surface 7.

Lubricant is supplied to the fourth lubricant groove 14 in the bearing bracket 13 through the lubricant supply hole 16 in the cylinder head and delivered to the bearing site. For lubricating the cam followers, lubricant flows out of the first camshaft bearing block 2 'and the second camshaft bearing block 3'. The outflow of the lubricant is shown by arrows.

Fig. 2 shows the associated bearing bracket 13 for the complete arrangement of the first camshaft bearing 2 and the second camshaft bearing 3. As already explained with reference to fig. 1, the lubricant is supplied through the lubricant supply bore 16 and is conveyed further on the exhaust side on the one hand and on the intake side on the other hand, which is also symbolically illustrated by the arrows. The lubricant in the fourth lubricant groove 14 is supplied to the bearing points in the bearing frame 13, the fourth lubricant groove 14 having a branching 9 in front of at least one of the bearing points 2, 3, so that the fourth lubricant groove 14 corresponds to both the second lubricant groove 11 and the third lubricant groove 12. In the present exemplary embodiment, a fork is used for the two camshaft bearings 2, 3.

Fig. 3 shows a plan view of the sliding camshaft 4 shown in three dimensions. The direction of rotation of the camshaft is shown by the arrow. The camshaft 4 has two cams 5, only one of which is provided with a reference numeral. The cam 5 has a first cam curved surface 6 and a second cam curved surface 7 having lift curves different from each other. The entire camshaft 4 can be moved axially in two positions on the camshaft section 8 by means of an actuator, not shown.

For the purpose of supplying lubricant for lubricating the cam followers, a fifth lubricant groove 15 which is at least partially surrounded in the radial direction is provided in the camshaft 4. If the fifth lubricant groove 15 is circumferential, the cam follower is continuously lubricated. If the fifth lubricant groove only surrounds in sections, the lubricant lubricates the cam follower in an oil-saving, intermittent manner.

Fig. 4 shows a sectional view of the camshaft 4 with the fifth lubricant groove 15. Fig. 4 also shows a cam 5 with a first cam curve 6 and a second cam curve 7. Since the moving mechanism of the camshaft 4 is known in the art, it will not be described in detail here.

A particularly preferred cam follower, not shown, is a sliding drag bar. The valve mechanism according to the present invention may be provided in the cylinder head 1 on both the intake side and the exhaust side.

List of reference numerals

1 Cylinder head

2 first camshaft bearing

2' first camshaft bearing seat

3 second camshaft bearing

3' second camshaft bearing seat

4 cam shaft

5 cam

6 first cam curved surface

7 second cam curve

8 camshaft section

9 bifurcation part

10 first lubricant sump

11 second lubricant groove

12 third lubricant sump

13 bearing bracket

14 fourth lubricant sump

15 fifth lubricant sump

16 lubricant supply hole