Sliding cam arrangement for variable actuation of gas exchange valves of an internal combustion engine

Abstract

Sliding cam arrangement for variable actuation of gas exchange valves of an internal combustion engine with a camshaft (6) having toothed areas (10) with external teeth (12), wherein the toothed areas (10) each engage with internal teeth (14) of a cam carrier (16), characterized in that the ratio of base circle radius R2 of the cam carrier (16) to tip circle radius R1 of the teeth (12) of the camshaft (6) is R2 / R1 = 1.33.

Description

[0001] The invention relates to a sliding cam arrangement for the variable actuation of gas exchange valves of an internal combustion engine with a camshaft, which has toothed areas with external teeth, wherein the toothed areas each engage with internal teeth of a cam carrier.

[0002] Such sliding cam arrangements are well known in the prior art. For example, DE 10 2008 035 935 A1 discloses a sliding cam arrangement comprising a camshaft with toothed sections, each featuring a cam carrier with two cams that engage with a corresponding gas exchange valve. Actuators are provided to shift the respective cam carriers. These actuators, via drive lugs and grooves on the cam carriers, enable axial movement of the cam carriers. In the automotive sector, optimizing installation space and weight, particularly with regard to increasing engine efficiency, is playing an increasingly important role. Against this backdrop, efforts to optimize camshaft arrangements have focused primarily on material optimization and improvement.Nevertheless, it has become apparent that existing sliding cam arrangements, particularly with regard to the negative effects of the moment of inertia of the cam carriers, have a considerable need for improvement.

[0003] The object of the invention is therefore to provide a sliding cam arrangement that provides improved dynamic behavior in a cost-effective and assembly-oriented manner.

[0004] This problem is solved by ensuring that the ratio of the base circle radius R2 of the cam carrier to the tip circle radius R1 of the camshaft's toothing (R2 / R1) is less than 1.55. This significantly improves the inertia behavior of the sliding cam assembly. Furthermore, the actuators require less power to move the respective cam carriers, resulting in a reduction in installation space and cost savings for the actuators as well. Even a potentially larger diameter camshaft, due to the need to maintain specified clearances in the cylinder head to the gas exchange valves, does not negatively impact the overall performance of the inventive sliding cam assembly. A ratio of R2 to R1 in the range of 1.2 to 1.55 has proven particularly advantageous.

[0005] The invention is explained in more detail below with reference to a drawing, which shows:

[0006] Fig. 1 A top view of a sliding cam assembly for part of a six-cylinder V-engine,

[0007] Fig. 2 a sectional view through a sliding cam arrangement in the area of ​​a cam carrier according to the prior art, and

[0008] Fig. 3 a section through a sliding arrangement according to the invention in the area of ​​a cam carrier.

[0009] Fig. Figure 1 shows a top view of a sliding cam assembly 2 for a series of a six-cylinder V-engine, of which three cylinders are shown here 4 are shown. On a camshaft 6 are in a known way between camps 8 Gear areas 10 provided for, which has an external toothing 12 (see here) Fig. 2 and Fig. 3) and each with internal teeth 14 a cam carrier 16in engagement. In the present embodiment, a cam carrier is provided for two gas inlet valves (not shown) and has grooves. 18 , which come with tow vehicles 20 of an actuator 22 interact in such a way that the respective cam carriers 16 in the axial direction on the camshaft 6 are movable. Each cam carrier 16 It also features a pair of cams 24 , 26 with cams 28 , 30 each of which can be engaged with the associated gas exchange valve and therefore cause a different stroke characteristic of the gas exchange valve. For the sake of completeness, it should also be noted that this refers to the one with reference number 32 designated component around a sprocket for driving the camshaft 6 it.

[0010] Fig. Figure 2 now shows a sectional view through a sliding cam arrangement. 2 According to the state of the art. The camshaft is clearly visible here. 6 , on which the cam carrier 16 with the cam 30 The camshaft has external teeth. 12 , which are connected to the internal teeth 14 of the cam carrier 16 is undergoing intervention. With 34 The tip circle of the gear teeth is shown. In a sliding cam arrangement according to the prior art, the ratio of R2 (base circle radius) to R1 (tip circle radius of the gear teeth) is generally > 1.5, in particular 1.6 to 1.8. It should be clear that R1 is the radius from the center of the camshaft. 6 to the tip circle of the external gearing 12 and with R2 the radius from the center of the camshaft 6 to the base circle of the cam carrier 16 is designated.

[0011] Fig.Figure 3 now shows the ratio of R2 to R1 in the sliding cam arrangement according to the invention. 2 Here, the ratio is < 1.55 with a matching base circle radius R2, and 1.33 in the exemplary embodiment. Although the camshaft has a greater weight due to the increased diameter, the entire sliding cam assembly possesses 2 a significantly more favorable dynamic behavior, achieved through the modified cam carriers 16 A significant weight saving was achieved. It should be clear that where the installation space and engine-specific situation allow, the camshaft 6 It can of course also be made with a smaller diameter, whereby even greater weight optimization can be achieved while maintaining the ratio R2 to R1. QUOTES INCLUDED IN THE DESCRIPTION

[0012] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0013] DE 102008035935 A1

[0002]

Claims

[1] Sliding cam arrangement for variable actuation of gas exchange valves of an internal combustion engine with one camshaft ( 6 ), the gear teeth ( 10 ) with an external toothing ( 12 ) exhibits, wherein the gear teeth ( 10 ) each with internal teeth ( 14 ) of a cam carrier ( 16 ) are in intervention, characterized by that the ratio of the base circle radius R2 of the cam carrier ( 16 ) to the pitch circle radius R1 of the gear teeth ( 12 ) the camshaft ( 6 ) R2 / R1 < 1.

55. [2] Sliding cam arrangement according to claim 1, characterized by that the ratio R2 / R1 is in the range of 1.2 to 1.55.

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