Variable valve drive for a reciprocating piston internal combustion engine

Abstract

The present invention provides a variable valve drive for a reciprocating piston internal combustion engine, having an intake valve. For each intake valve having the same function, the variable valve drive has: the valve opening being pre-given respectively by a cam of a camshaft, and being selectively cut off or switched to another reciprocating motion process by means of a switchable valve push rod through the movement of a switching pin guided in the valve push rod bore. The switching pin of the valve push rod is connected via a spring tongue configured as a leaf spring to a push strip configured as a track, the push strip being arranged parallel to the camshaft and being longitudinally movable by means of a linear actuator against the restoring force of a spring element. The upper ends of the spring tongues are each bent as tabs and fastened to the push strip by means of a first fastening element, and the lower ends of the spring tongues are abutted against the outer end walls of the respective switching pins. The upper ends of the spring tongues have additional fastening elements for fastening them to the push strip, the additional fastening elements being configured as clamps.

Description

Technical Field

[0001] The invention relates to a variable valve drive for a reciprocating piston internal combustion engine, which has at least one functionally identical intake valve for each cylinder. The variable valve drive has the following features for each functionally identical intake valve: the valve opening is pre-given by at least one cam of the camshaft, and by means of a switchable valve push rod, it can be selectively cut off or switched to another reciprocating motion process by the movement of a switching pin guided in the hole of the valve push rod. The switching pin of the valve push rod is connected to a push plate strip configured as a track via a spring tongue configured as a leaf spring. The push plate strip is arranged parallel to the camshaft and can be longitudinally moved against the restoring force of a spring element by means of a linear actuator. And the upper end portions of the spring tongues are respectively bent as tabs and fastened to the push plate strip by means of a first fastening element, and the lower end portions of the spring tongues are abutted against the outer end walls of the respective switching pins. Background Art

[0002] This type of valve drive is known from DE102018103961A1. In this design, the spring tongue is connected to the push plate strip by means of a clinch connection. It has been shown that the fastening of the spring tongue or the tab of the spring tongue on the push plate strip at the fastening site is not sufficient to ensure that the spring tongue is permanently fastened to the push plate strip, even when the fastening site is a solder joint. Due to the intermittent load at the lower end portion of the spring tongue, the fastening site will break. Summary of the Invention

[0003] The object of the invention is to provide a variable valve drive in which the respective spring tongues are permanently and simply fastened to the push plate strip.

[0004] According to the invention, this object is achieved in that the upper end portion of the spring tongue has a further fastening element for fastening it to the push plate strip, and the further fastening element is configured as a clamp.

[0005] By means of the further fastening element, the movement of the spring tongue or the tab on the push plate strip is prevented or reduced to an extent that ensures the permanent fastening of the spring tongue to the push plate strip.

[0006] In a design of the invention, it is proposed that the clamp is constructed and arranged in such a way that it resists the pivoting or lifting of the spring tongue from the push plate strip at the fastening element.

[0007] According to an improved embodiment of the present invention, a clamp is obtained in the following manner, namely, the spring tongue has a tab section which, in the assembled state of the spring tongue, extends substantially parallel to the tab but on the other side of the push bar, and in this case, together with the tab, it bows and clamps the push bar on its longitudinal side and is oriented from there towards the end wall of the switching pin.

[0008] The spring tongue is preferably made of spring steel and generates a pressing force between the tab and the tab section.

[0009] Since, in the unassembled state of the spring tongue, the distance between the tab and the tab section is less than or exactly equal to the thickness of the push bar, tensioning of the spring tongue on the push bar is achieved. "Thickness" is understood as the distance between the upper and lower sides of the push bar. The width of the tab section is substantially equivalent to the width of the tab here, so that the entire pressing force of the spring tongue is effective.

[0010] Finally, it is proposed that, when viewed in the longitudinal direction of the push bar, the clamp is constructed as a spring clip that surrounds and clamps the push bar by spring force at least on one side of the tab. Spring clips can also be provided on both sides of the tab. Description of the Drawings

[0011] The present invention is described in the drawings:

[0012] · Figure 1 A cross-sectional view through the push bar is shown, which has a spring tongue fastened thereto;

[0013] · Figure 2 The spring tongue according to Figure 1 is shown without the push bar;

[0014] · Figure 3 A perspective view of the spring tongue with a spring clip on the push bar is shown;

[0015] · Figure 4 A cross-sectional view through the push bar according to Figure 3 is shown while observing the spring tongue; and

[0016] · Figure 5 A perspective view of the spring tongue fastened to the push bar by an engagement connection between the push bar and the spring tongue and the spring clip is shown. Detailed Description of the Embodiment

[0017] In Figures 1 to 5 the push bar labeled with reference numeral 1 is shown in detail. The push bar is supported and guided (not shown) parallel to the camshaft of a reciprocating piston internal combustion engine. The push bar is arranged near a valve push rod, which is also not shown, so that the longitudinal movement of the push bar 1 can be transmitted to the end wall of the switching pin on the valve push rod by means of the spring tongue 2.

[0018] The spring tongue 2 has a tab 3 each, which is bent and arranged on the side of the push strip 1 and fastened to the push strip 1. The fastening can be achieved in any known manner by means of a snap connection 6 (see below), by welding, riveting, etc.

[0019] As can be seen from Figure 1 and Figure 2 it can be seen that the spring tongue 2 also has a tab section 4, which is arranged beside the tab 3 and is constructed in such a way that the tab section surrounds the push strip 1 by means of a pressing force ( Figure 1 ). To ensure a permanent pressing force, the spring tongue 2 is made of spring steel. Then, an arm of the spring tongue 2 is connected to the tab section 4 and guides up to the switching pin.

[0020] According to Figures 3 to 5 , the spring tongue 2 has, in addition to the tab 3, a spring clip 5, which is fastened to the tab 3 and is preferably integrally formed with the tab. The spring clip 5 is constructed in such a way that it surrounds the push strip 1 by means of a spring force in a manner similar to the tab section 4.

[0021] Figure 5 A perspective view from the lower end of the spring tongue 2 is shown. It can be seen here that, in addition to the spring clip 5, the spring tongue 2 is connected to the push strip 1 by means of a so-called snap connection 6, which is the main fastening part.

[0022] By means of Figure 1 and 2 the tab section 4 in

[0023] List of reference numerals

[0024] 1) Push strip

[0025] 2) Spring tongue

[0026] 3) Tab

[0027] 4) Tab section

[0028] 5) Spring clip

[0029] 6) Snap connection

Claims

1. A variable valve drive for a reciprocating piston internal combustion engine, the variable valve drive having at least one functionally identical charge exchange valve for each cylinder, wherein, The variable valve drive has the following features for each functionally identical intake valve: The valve opening is respectively preset by at least one cam of the camshaft, and by means of a switchable valve push rod, it can be selectively cut off or switched to another reciprocating motion process by the movement of a switching pin guided in the hole of the valve push rod. The switching pin of the valve push rod is connected to a push strip (1) constructed as a guide rail via a spring tongue (2) constructed as a leaf spring. The push strip is arranged parallel to the camshaft and can be longitudinally moved by means of a linear actuator against the restoring force of a spring element. And the upper end parts of the spring tongues (2) are respectively bent as tabs (3) and fastened to the push strip (1) by means of a first fastening element, and the lower end parts of the spring tongues are abutted against the outer end walls of the respective switching pins. It is characterized in that the upper end parts of the spring tongues (2) have additional fastening elements for fastening them to the push strip (1), and the additional fastening elements are constructed as clamps.

2. The variable valve train according to claim 1, characterized in that, The clamp is constructed and arranged such that it resists the spring tongue (2) from pivoting or lifting from the push strip (1) at its first fastening element.

3. The variable valve train according to claim 1 or 2, characterized in that, The clamp is obtained in such a way that the spring tongue (2) has a tab section (4), in the assembled state of the spring tongue (2), the tab section is substantially parallel to the tab (3) but extends on the other side of the push strip (1), and here, the tab section and the tab (3) together bow and clamp the push strip (1) on one of its longitudinal sides and are directed from this longitudinal side to the end wall of the switching pin.

4. The variable valve train according to claim 1, characterized in that, The spring tongue (2) is made of spring steel.

5. The variable valve drive according to claim 3, characterized in that, In the unassembled state of the spring tongue (2), the distance between the tab (3) and the tab section (4) is less than or exactly equal to the thickness of the push strip (1).

6. The variable valve train according to claim 1 or 2, characterized in that, Viewed in the longitudinal direction of the push strip (1), the clamp is constructed as a spring clip (5) that surrounds and presses the push strip (1) by means of spring force at least on one side of the tab (3).

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