DE102022112943A1 - Valve train component for an at least partially pneumatically operated valve train of an internal combustion engine - Google Patents

Abstract

Valve train component (1) for an at least partially pneumatically operated valve train (2) of an internal combustion engine with an actuating device (3) for opening and/or closing a valve (12). The actuating device (3) comprises a gas pressure spring device (4) with a spring cylinder (14) and a spring piston (34) movably received in a cylinder space (24) of the spring cylinder (14). The spring piston (34) can be coupled to the valve (12), so that the spring piston (34) moves together with the valve (12) when the valve (12) is opened and closed. The spring piston (34) can be moved along a movement path (5) in the cylinder chamber (24). The movement path (5) runs between two dead centers (15, 25). During operation, the movement of the spring piston (34) undergoes a reversal of direction at the dead centers (15, 25). The cylinder space (24) is rotationally symmetrical along the movement path (5) and has a variable diameter (6) at least in sections.

Description

The present invention relates to a valve train component for an at least partially pneumatically actuated valve train of an internal combustion engine with at least one actuating device for opening and/or closing at least one valve of the internal combustion engine. The actuating device comprises at least one gas pressure spring device with a spring cylinder and a spring piston movably received in a cylinder space of the spring cylinder.

With such a valve train component, the gas pressure spring device can be used, for example, as a purely pneumatic valve spring or in combination with a mechanical valve spring. The use of a gas pressure spring device in valve trains fundamentally offers many advantages. However, for reliable and energy-saving operation, it is crucial that the excess pressure present in the gas pressure spring device during operation lasts as long as possible and is not lost through leaks. The gas pressure spring device must therefore be reliably sealed.

From the DE 10 2008 006 777 B4 A valve drive with a gas pressure spring with a pressure chamber for pneumatic reset is known. To seal between the pressure chamber and a pressure piston, a seal is provided, which is either fixed in place in the pressure chamber or fixed in place on the pressure piston. In addition, a shaft of a gas exchange valve has a seal for a valve guide and the pressure piston.

From the EP 2 232 021 B1 a pneumatic valve drive with a gas pressure spring is known, in which seals are arranged between the pressure chamber and the pressure piston and between the pressure chamber and the valve stem.

In contrast, the object of the present invention is to provide a valve train component with an improved gas pressure spring device. In particular, any pressure loss that occurs during operation should be counteracted. Preferably, the solution should be structurally uncomplicated and fail-safe to implement.

This object is achieved by a valve train component with the features of claim 1. Preferred developments of the invention are the subject of the subclaims. Further advantages and features of the present invention emerge from the general description and the description of the exemplary embodiment.

The valve train component according to the invention is for an at least partially pneumatically operated valve train of an internal combustion engine. The valve train component comprises at least one actuating device for opening and/or closing at least one valve of the internal combustion engine. The actuating device comprises at least one gas pressure spring device with a spring cylinder and a spring piston. The spring piston is movably accommodated in a cylinder space of the spring cylinder. The spring piston can be coupled to the valve so that the spring piston moves together with the valve when the valve is opened and closed. The spring piston can be moved along a movement path in the cylinder space. The trajectory runs between two dead centers. During operation, the movement of the spring piston undergoes a reversal of direction at the dead centers. The cylinder space is rotationally symmetrical along the movement path and at least partially designed with a variable diameter. The two dead centers include in particular a first dead center and a second dead center.

The valve train component according to the invention offers many advantages. The cylinder chamber with its variable diameter offers a significant advantage. This achieves a significantly improved seal between the spring piston and the spring cylinder, so that lower pressure losses occur during operation. This allows the energy required to provide the pressure to be saved. In addition, the targeted adjustment of the diameter also enables the friction properties to be improved. Furthermore, a better response behavior of the gas pressure spring device can be achieved.

In a particularly advantageous and preferred embodiment, the variable diameter of the cylinder space is produced by means of surface fine machining and preferably by means of shape honing of an inner wall of the spring cylinder. This enables a particularly reliable and at the same time inexpensive implementation of the invention. In addition to an improved sealing effect, this also results in advantages for the friction and play between the spring piston and the spring cylinder. In particular, the surface finishing is provided at least where the spring piston runs along the inner wall of the cylinder chamber on its path of movement. In particular, the surface finishing takes place on a prepared inner wall of the spring cylinder. In particular, shape honing is carried out using a honing tool whose machining diameter is adjustable and is preferably adjustable during the honing process.

Preferably, the diameter of the cylinder space has a minimum at least at one of the dead centers. This makes the advantages of diameter adjustment particularly effective.

Preferably, a smallest (minimum) diameter of the cylinder space is present at least at a first dead center. In particular, at the first dead center, a working fluid located in the cylinder chamber is subjected to a higher pressure when the spring piston is at the first dead center than when the spring piston is at the second dead center. In other words, when the spring piston is at first dead center, the pressure in the cylinder chamber is at its highest. By arranging the smallest diameter at such a dead center, the optimized diameter has a particularly advantageous effect on the pressure loss.

In particular, the spring piston and the spring cylinder delimit a pressure space. In particular, the pressure chamber is part of the cylinder chamber. In particular, the pressure space is reduced by a movement of the spring piston in the direction of the first dead center and increased by a movement of the spring piston in the direction of the second dead center. In particular, the pressure space is smallest when the spring piston is at first dead center. In particular, the pressure space is largest when the spring piston is at second dead center. In particular, the pressure of the working fluid is greatest when the pressure space is smallest. In particular, the working fluid in the cylinder space is more compressed when the spring piston is at the first dead center than when the spring piston is at the second dead center.

It is advantageous and preferred that the diameter of the cylinder space at the second dead center is equal to or larger than the diameter of the cylinder space at the first dead center. For example, a larger diameter at the second dead center can reduce the friction between the spring piston and the spring cylinder.

It is possible and advantageous for the diameter of the cylinder space to have a maximum between the dead centers. In particular, the cylinder space has a smaller diameter at at least one of the dead centers than in a central area between the dead centers. In particular, the diameter is largest in the central area between the dead centers. The dead centers are then particularly identical in terms of their diameter. In particular, the diameter is then the same size at both dead centers.

It is also possible and advantageous for the diameter of the cylinder space to have a maximum at the second dead center. Then the diameter in the central area is preferably designed to increase at least in sections in the direction of the second dead center.

In an advantageous and preferred development, the diameter changes continuously at least in sections along the movement path. In particular, the cylinder space therefore has rounded bulges and/or constrictions. In particular, a continuous change in the diameter does not mean a constant change in the diameter. The continuous change in diameter particularly describes a curve-like course. The bulge corresponds in particular to a convex enlargement of the cylinder space. This also offers many advantages and enables, for example, a reduction in friction in the area between the dead centers, while a reliable sealing effect is achieved at the dead centers.

It is possible and advantageous for the diameter to change constantly at least in sections along the movement path. In particular, this results in a conical cylinder space at least in sections. It is possible for the cylinder space to be conical along the entire path of movement. It is also possible for the cylinder space to be cylindrical at one or both dead centers and at least partially conical in between. In particular, the conical cylinder space has a minimum diameter at the first dead center.

In an advantageous embodiment, it is possible for the diameter not to change at all along the movement path in sections. In particular, this results in a cylinder space that is cylindrical in sections. A cylindrical design of the cylinder chamber is advantageous, for example, at one or both dead centers. It is also possible that the cylinder space between the dead centers is at least partially cylindrical. Then the cylinder space preferably has a variable diameter at the dead centers.

It is possible that the diameter changes stepwise in sections along the movement path. As a result, at least one edge in particular appears in the cylinder space. It is possible for such an edge to be rounded. In particular, the edge is rounded off with a defined radius.

In particular, (all) changes in diameter are rounded. In particular, the cylinder space is in the direction of movement supply track is at least partially rounded. In particular, the transitions from a cylindrical section to a section with a variable diameter are also rounded. However, angular or step-like transitions can also be provided.

The diameter can change along the movement path at least in sections with different rates of change. Preferably, a transition from one rate of change to another rate of change is harmonious or rounded, so that no edge occurs in the cylinder space.

The cylinder space is designed with a variable diameter at least where the spring piston moves along its path of movement along the inner wall of the spring cylinder. The rotationally symmetrical design of the cylinder space relates in particular to its longitudinal axis. The longitudinal axis of the cylinder space extends in particular in the direction of the movement path of the spring piston. In particular, the gas pressure spring device serves at least to reset the valve after an actuation. In particular, the gas pressure spring device corresponds to a valve spring. In particular, air or compressed air is provided as the working medium.

The spring piston includes in particular a piston body. The spring piston in particular also includes a piston seal. In particular, the piston seal is arranged on the piston body. In addition or as an alternative to the piston seal, a sealing device can be arranged on the spring cylinder, which serves to seal between the spring piston and the spring cylinder.

In particular, the piston seal touches the inner wall of the spring cylinder at dead center when the spring piston is at the end of its path of movement. In the context of the present invention, the diameter of the cylinder space at dead center is understood to mean, in particular, the diameter that the cylinder space has where the spring piston, in particular with its piston seal, rests on the inner wall of the spring cylinder when it is at the end of its path of movement. In particular, the dead center in the context of the present invention therefore also corresponds to a specific part of the spring cylinder.

Further advantages and features of the present invention result from the exemplary embodiments, which are explained below with reference to the accompanying figures.

• 1 eine rein schematische Darstellung einer erfindungsgemäßen Ventiltriebkomponente in einer geschnittenen Seitenansicht; und
• 2a-2h stark schematisierte Detaildarstellungen von Zylinderräumen einer erfindungsgemäßen Ventiltriebkomponente.

Show in the figures:

• 1 a purely schematic representation of a valve train component according to the invention in a sectioned side view; and
• 2a-2h highly schematic detailed representations of cylinder spaces of a valve train component according to the invention.

The 1 shows a valve train component 1 according to the invention, as can be used, for example, for the pneumatic actuation of a valve train 2 of a reciprocating piston engine of a motor vehicle. Of the valve train 2, only a valve stem 22 of a valve 12 is shown here. The valve 12 is opened and/or closed using an actuating device 3, of which only one gas pressure spring device 4 is shown here. The gas pressure spring device 4 serves, for example, as a valve spring to reset the valve 2 after an actuation.

The gas pressure spring device 4 comprises a spring cylinder 14 with a cylinder space 24 formed therein. The cylinder space 24 is designed to be rotationally symmetrical. A spring piston 34 is movably accommodated in the cylinder space 24. The spring piston 34 is coupled to the valve stem 22 via a holding element 32. As a result, the spring piston 34 moves together with the valve 12 when the valve 12 is opened and closed.

The valve stem 22 is sealed to the spring piston 34 with a stem seal 42. In addition, an opening is formed in a bottom of the spring cylinder 14, through which the valve stem 22 extends out of the spring cylinder 14. There the valve stem 22 is sealed to the spring cylinder 14 with a stem seal 52.

During operation, the spring piston 34 moves along a movement path 5 in the cylinder space 24. The movement path 5 extends here between two dead centers 15, 25. At the dead points 15, 25, the movement of the spring piston 34 undergoes a reversal of direction.

During operation, the cylinder chamber 24 is supplied with a working fluid and, for example, compressed air via a spring valve 54. The spring valve 54 closes without further pressure supply. To seal the cylinder chamber 24, the spring piston 34 is here equipped with a piston seal 341, which extends around a rotationally symmetrical piston body 340. The piston seal 141 lies sealingly against an inner wall 44 of the spring cylinder 14.

In the cylinder chamber 24, an undesirable escape of compressed air can occur on the sealing surfaces of the spring piston 34. To counteract this loss is the cylinder space 24 here is formed in sections with a variable diameter 6. The variable diameter 6 has a minimum here at the first dead center 15. As a result, a particularly effective seal is achieved when the pressure in the cylinder chamber 24 is greatest.

When the spring piston 34 moves away from the first dead center 15 and the pressure decreases, a constant diameter 6 is provided here. For this purpose, the cylinder space 24 is cylindrical above the first dead center 15. The transition from the conical to the cylindrical cylinder space 24 can be equipped with an edge (such as in the 2 B shown). The edge 8 can also be rounded (as for example in the 2c shown).

The cylinder chamber 24 in the 1 Valve train component 1 shown can also be equipped with a different geometry if necessary. Alternative and advantageous geometries for the cylinder space 24 are in the 2a until 2h shown as an example. The size ratios shown here for the course of the diameter 6 are purely schematic and in particular not shown to scale and serve for illustration. For example, the one in the 1 shown conical section of the cylinder space 24 can be shorter or longer.

The 2a shows a conical cylinder space 24. The 2 B shows a cylinder space 24, which is cylindrical at the dead centers 15, 25 and conical in between. Edges 8 are formed at the transitions. The edges 8 can also be rounded, such as in the 2c shown. The 2d shows a cylinder space 24 in which the second dead center 25 has a maximum diameter. At the first dead center 15, the cylinder space 24 is cylindrical and has the smallest diameter 6.

The 2e until 2h show cylinder spaces 24 with bulges 7. The cylinder spaces 24 have the minimum diameter 6 at the dead centers 15, 25. In between, the cylinder space 24 is completely or partially equipped with a bulge 7.

The invention presented here enables a significant reduction in compressed air loss during operation of the gas pressure spring device 4. This allows, for example, a compressed air tank to be made smaller or a compressed air pump has to generate less compressed air, so that lower losses occur and energy can be saved. At the same time, the play between spring piston 34 and cylinder chamber 24 influences both the leakage losses and the friction between this sliding pair.

To optimize leakage and friction losses, the valve train component 1 presented here was subjected to surface finishing. For this purpose, the inner wall 44 of the spring cylinder 14 is produced by means of mold honing. The shape honing gives the spring cylinder 14 its rotationally symmetrical shape and the specifically variable diameter 6.

List of reference symbols:

1

Valve train component

2

Valve train

3

Actuating device

4

Gas spring device

5

trajectory

6

diameter

7

bulge

8th

Edge

12

Valve

14

Spring cylinder

15

dead center

22

valve stem

24

Cylinder space

25

dead center

32

Holding element

34

Spring piston

42

Shaft seal

44

inner wall

52

Shaft seal

54

Spring valve

340

Piston body

341

Piston seal

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008006777 B4 [0003]
• EP 2232021 B1 [0004]

Claims (11)

Valve drive component (1) for an at least partially pneumatically operated valve drive (2) of an internal combustion engine with at least one actuating device (3) for opening and/or closing at least one valve (12) of the internal combustion engine, the actuating device (3) having at least one gas pressure spring device (4) with a spring cylinder (14) and a spring piston (34) which is movably accommodated in a cylinder space (24) of the spring cylinder (14), the spring piston (34) being coupled to the valve (12), so that the spring piston (34) is at Opening and closing of the valve (12) moves together with the valve (12), the spring piston (34) being movable along a movement path (5) in the cylinder chamber (24) and the movement path (5) between two dead centers (15, 25 ) runs and the movement of the spring piston (34) undergoes a reversal of direction during operation at the dead centers (15, 25), characterized in that the cylinder space (24) along the movement path (5) is rotationally symmetrical and at least in sections with a variable diameter ( 6) is trained. Valve train component (1) according to the preceding claim, wherein the variable diameter (6) of the cylinder space is produced by means of surface fine machining and preferably by means of shape honing of an inner wall (44) of the spring cylinder (14). Valve train component (1) according to one of the preceding claims, wherein the diameter (6) of the cylinder chamber (24) has a minimum at least at one of the dead centers (15, 25). Valve drive component (1) according to one of the preceding claims, wherein a smallest diameter (6) of the cylinder space (24) is present at least at a first dead center (15) and wherein a working fluid (e.g. air) located in the cylinder space (24) with a higher pressure is applied when the spring piston (34) is at the first dead center (15) than when the spring piston (34) is at the second dead center (25). Valve train component (1) according to one of the preceding claims, wherein the diameter (6) of the cylinder space (24) at the second dead center (25) is equal to or larger than the diameter (6) of the cylinder space (24) at the first dead center (15). Valve train component (1) according to one of the preceding claims, wherein the diameter (6) of the cylinder space (24) has a maximum between the dead centers (15, 25) or wherein the diameter (6) of the cylinder space (24) at the second dead center (25) has a maximum. Valve drive component (1) according to one of the preceding claims, wherein the diameter (6) changes continuously at least in sections along the movement path (5), so that the cylinder chamber (24) has rounded bulges (7). Valve drive component (1) according to one of the preceding claims, wherein the diameter (6) changes constantly at least in sections along the movement path (5), so that a conical cylinder space (24) results at least in sections. Valve drive component (1) according to one of the preceding claims, wherein the diameter (6) does not change at all along the movement path (5) in sections, so that a cylinder space (24) is cylindrical in sections. Valve drive component (1) according to one of the preceding claims, wherein the diameter (6) changes stepwise in sections along the movement path (5), so that at least one edge (8) appears in the cylinder space (24). Valve train component (1) according to the preceding claim, wherein the edge (8) is rounded.

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