Positioning screw for a roller tappet

Abstract

The present invention relates to positioning screws for a tappet of an internal combustion engine, in particular a roller tappet, and to methods for positioning a tappet of an internal combustion engine. Accordingly, a positioning screw (10) for a tappet (12) of an internal combustion engine is proposed, comprising a first section (18) which is elongated and defines a longitudinal axis (10A) of the positioning screw (10), wherein the first section (18) is designed to be at least partially received in a through-bore (20) of a crankcase (16) in the assembled state. The positioning screw (10) further comprises a second section (22) which is designed to engage with a recess (24) of the tappet (12) in the assembled state of the positioning screw (10) and in the received state of the tappet (12) in the crankcase (16).The second section (22) is designed with a radial offset to the longitudinal axis (10A).

Description

Technical field

[0001] The present invention relates to a positioning screw for a tappet of an internal combustion engine, in particular a roller tappet, and a method for positioning a tappet of an internal combustion engine. State of the art

[0002] In internal combustion engines, for example with a Miller combustion process, tappets are typically used to open valves. These tappets engage with a respective cam of a camshaft and thus enable the actuation of the respective valve. Tappets can be flat tappets or roller tappets, in particular, which provide a translational movement due to the rotation of the respective cam. During operation, however, it is important to prevent the tappet from twisting relative to the cam, especially since this can lead to significant damage to the cam surface, such as pitting or so-called "Pitting" can lead to.

[0003] To minimize adverse cam wear, a positioning screw can be provided for the tappet, which can significantly reduce potential twisting of the tappet around its longitudinal axis and on the cam base circle. In other words, such a positioning screw allows for very small potential twisting. It has been found that the smaller this potential twisting, the smaller the stress on the cam surface and the tappet contact area, especially on the roller of a roller tappet.

[0004] In the case of a roller tappet, the potential twist is primarily defined by the groove width in the roller tappet and the diameter at the tip of the positioning screw. The position tolerance of the corresponding bore in the crankcase for both the positioning screw and the roller tappet itself plays a significant role. However, it was recognized in this case that this position tolerance is often not further optimizable or that doing so would involve considerable expense and time. However, such optimizations are still significantly limited in terms of manufacturing technology and do not allow for individual adjustment of the position during assembly. Description of the invention

[0005] Based on the known prior art, it is an object of the present invention to provide an improved positioning screw for a tappet of an internal combustion engine and a corresponding method.

[0006] The problem is solved by a positioning screw having the features of claim 1. Advantageous further developments emerge from the subclaims, the description and the figures.

[0007] Accordingly, a positioning screw for a tappet of an internal combustion engine is proposed, comprising a first section which is elongated and defines a longitudinal axis of the positioning screw. The first section is designed to be at least partially received in a through-bore of a crankcase in the assembled state. The positioning screw further comprises a second section which is designed to engage with a recess in the tappet in the assembled state of the positioning screw and in the received state of the tappet in the crankcase. According to the invention, the second section is designed with a radial offset to the longitudinal axis.

[0008] Because the positioning screw has a second section which engages with the recess, in particular a groove, opening or bore of the tappet and is in particular received therein, the position of the tappet can be adjusted by means of the corresponding translational movement by rotating the positioning screw. In this way, it can be ensured that sufficient contact is provided between the tappet and a cam of a crankshaft. The position can also be adjusted in a force-controlled manner based on a predetermined torque, for example in the range between 1 Nm and 10 Nm, so that it can advantageously be ensured that no excessive force is exerted on the tappet or the cam during contact. Accordingly, the risk of increased wear or impairment of the functionality of the tappet can also be minimized.

[0009] In other words, by rotating the positioning screw, an optimal angular position can be set, allowing any positional tolerances between the tappet and a cam to be compensated for in a simple yet precise manner in the translational direction. The adjustment can be virtually stepless and / or, preferably, with an accuracy of approximately one degree.

[0010] Both the first section and the second section are preferably formed from a metal or metal alloy, and in particular as a solid material. This can provide improved stability of the positioning screw. Likewise, the first section and the second section are preferably formed in one piece or from one part and / or monolithically.

[0011] Although the positioning screw can be designed for various types of tappets, it is preferably designed for a roller tappet. Especially with roller tappets, rotation around its own axis can occur more frequently if the contact is inadequate, leading to a blockage of the roller and potentially serious damage.

[0012] The second section can preferably extend from an end region of the first section in the longitudinal direction and / or in the radial direction. For example, the second section can be designed as an eccentric and extend substantially or exclusively in the longitudinal direction or can also have a radial extension and thus an inclined orientation with respect to the first section. The second section can thus form a tip of the positioning screw, which can be rotated within a radius by means of a rotation of the positioning screw about the longitudinal axis and can accordingly effect an adjustment of the positioning of the plunger. The first section and second section are furthermore preferably arranged adjacent to one another, wherein the extension of the second section can be provided directly from the end region of the first section, for example from an end face and / or on the circumference of the first section.

[0013] A radial extent of the second section, starting from the longitudinal axis, can be greater than a radial extent of the first section. The second section, for example in the form of an eccentric, can be designed, for example, as a projection which extends from the end region of the first section and, due to the offset from the longitudinal axis, is not arranged concentrically with the first section, but rather protrudes radially therefrom. As a result, there is an asymmetry in the adjacent region between the first section and the second section, so that the second section can form a step and / or an inclined region with the first section in longitudinal section. In cross-section, the second section and the first section are accordingly arranged so as to only partially overlap one another.

[0014] With such a design, material costs can be significantly reduced, even if the first section and the second section are preferably formed from a solid material.

[0015] Alternatively, it can also be provided that a cross-section of the second section completely overlaps with a cross-section of the first section. In such a configuration, a particularly robust positioning screw can be provided in order, for example, to be able to better compensate for any leverage effects in the positioning screw when an eccentric is engaged. In this respect, full-surface, material-to-material contact between the second section and the first section can also be ensured, thereby possibly providing greater load-bearing capacity for the second section. Furthermore, with such a configuration, insertion into a corresponding bore in the crankcase can be made easier.

[0016] The second section preferably defines a free end and / or a tip of the positioning screw. In other words, the first section and the second section are preferably arranged adjacent to one another, but no further section is provided at the opposite end region of the second section, so that the second section is exposed and can thus advantageously be received in a recess such as a groove or bore in the tappet. The second section preferably forms a tip of the positioning screw.

[0017] The first section can be pin-shaped and / or cylindrical and / or have a circular cross-section. Likewise, the second section can also be pin-shaped and / or cylindrical and / or have a circular cross-section.

[0018] In other words, the first section and / or the second section, preferably both sections, can preferably be designed as an elongated body and substantially in a screw shape, wherein the second section is preferably either (fully) integrated in the cross-section of the first section or the latter is arranged with an at least partial radial offset from the cross-section of the first section. In the latter case, a predetermined overlap is thus provided due to the extension of the second section relative to and / or from the first section, which overlap can be predetermined, for example, based on the required load-bearing capacity or load-carrying capacity and / or stability. The offset from the longitudinal axis can be selected such that no significant lateral or rotational movement of the plunger is provided when the angular position of the positioning screw is adjusted.Preferably, the offset to the longitudinal axis and / or a radial extension of the second section relative to the longitudinal axis is between one tenth of a millimeter and ten tenths of a millimeter, preferably between one tenth of a millimeter and five tenths of a millimeter.

[0019] In order to ensure a more stable adjustment of the positioning screw, the first section preferably has an external thread, wherein a radial extension of the second section starting from the longitudinal axis is preferably smaller than a radial extension of the external thread.

[0020] The external thread allows the positioning screw to engage with a corresponding receptacle in the crankcase, preferably an internal thread, which facilitates adjustment of the angular position of the positioning screw and supports the bearing of the tappet. The thread also prevents accidental lateral sliding of the positioning screw and decoupling from the tappet.

[0021] Furthermore, the smaller radial extension of the second section can facilitate insertion of the second section through a bore or opening in the crankcase. This is because the greatest possible distance between a point on the circumference of the second section and a point on the circumference of the first section in the radial direction can always be smaller than the total diameter provided by the thread and the first section.

[0022] To further facilitate the insertion of the positioning screw, the first section can have a stop which is designed to engage with a wall of the crankcase when the positioning screw is at least partially assembled. The wall of the crankcase can be formed, for example, by a wall surface in a recess or bore in the outer wall, so that the stop is partially received in such a bore during insertion and can, for example, be brought into engagement with a corresponding edge. In this way, it can be easily ensured that the positioning screw is the correct length, for example by tightening it, inserting it, or screwing it in as far as it will go. The positioning screw can then be turned back one turn, for example, to compensate for the position tolerances.

[0023] The first section can have a receptacle for a fastening means in a region longitudinally opposite the second section, which receptacle is arranged such that the fastening means engages with a wall of the crankcase when received. Such a receptacle can, for example, also be provided as a thread, wherein the fastening means is preferably a nut. The receptacle or the thread is preferably arranged such that a further external thread on the first section, which preferably engages with an internal thread in the crankcase and is provided for inserting and / or supporting the positioning screw, lies between the receptacle and the second section. The receptacle thus preferably forms an external thread at the end region, so that the positioning screw can be fastened or fixed in particular to an external wall of the crankcase.This last thread outside the crankcase can then be used for a nut, for example, which can be tightened when the positioning screw is in the correct angular position.

[0024] The above-mentioned object is further achieved by a method for positioning a tappet of an internal combustion engine having the features of claim 11. Accordingly, a method for positioning a tappet of an internal combustion engine is proposed, comprising the steps: Providing a positioning screw according to the invention; positioning the tappet on an opening ramp or closing ramp of a cam of the internal combustion engine and rotating the positioning screw into a through-bore of the tappet to a first position with a predetermined torque; positioning the tappet on the respective other ramp of the cam and rotating the positioning screw into the through-bore of the tappet to a second position with the predetermined torque; tightening the positioning screw in a third position between the first position and the second position.

[0025] The positioning screw can be inserted into a bore in the crankcase and, using a thread, inserted into a corresponding recess or groove on the tappet using the appropriate screwing motion. To find the correct angular position of the positioning screw, the roller tappet is positioned on the opening or closing ramp of the cam by rotating the crankshaft. With the crankshaft in this position, the positioning screw is turned in one direction until a specified torque is reached. This angular position can be marked, for example, with a pin.As explained above, the torque, for example in the range between 1 Nm and 10 Nm, ensures that the adjustment of the position can take place in a force-controlled manner, so that it can advantageously be ensured that no excessive force is exerted on the plunger or the cam during contact and, at the same time, it is ensured that sufficient and / or intended contact is provided.

[0026] This process is repeated by turning the positioning screw in the other direction or with the tappet positioned on the other ramp of the cam, and a mark can be made accordingly. The positioning screw can then be tightened firmly in a third position, preferably in the center of the marked area.

[0027] In this way, position tolerance compensation of the tappet relative to the respective cam can not only be made easier, but also with considerably greater accuracy, so that optimal contact between the tappet, for example a roller of a roller tappet, and the corresponding cam can be provided and internal rotation of the tappet can be avoided as far as possible. Short description of the characters

[0028] Preferred further embodiments of the invention are explained in more detail by the following description of the figures. In the figures: Figure 1 a schematic sectional view of a portion of a crankcase of an internal combustion engine with a received roller tappet and an advantageous embodiment of an inserted positioning screw according to the invention; Figure 2Aa cross-section of the positioning screw according to the invention in a plan view in the longitudinal direction or at the adjacent region of the first section and the second section according to an embodiment; and Figure 2B a cross-section of the positioning screw according to the invention in a plan view in the direction of the longitudinal direction or at the adjacent region of the first section and the second section according to a further embodiment. Detailed description of preferred embodiments

[0029] Preferred embodiments are described below with reference to the figures. Identical, similar, or equivalent elements in the various figures are provided with identical reference numerals, and a repeated description of these elements is partially omitted to avoid redundancies.

[0030] In Figure 11 schematically shows an advantageous embodiment of a positioning screw 10 according to the invention in an assembled state. The positioning screw 10 is shown in a state in which it fixes a tappet 12 in a receptacle 14 of a section of a crankcase 16 of an internal combustion engine. The positioning screw 10 has a first section 18, which is cylindrical or pin-shaped and extends as an elongated body, such that the first section 18 defines a longitudinal axis 10A of the positioning screw 10. The first section 18 is at least partially inserted into a bore 20 in the crankcase 16, such that the positioning screw 10 provides a connection between the tappet 12 and the crankcase 16.

[0031] Adjacent to the first section 18, a second section 22 of the positioning screw 10 is provided, which in this case extends longitudinally from an end region of the first section 18. As shown, the second section 22 is exemplary designed as an eccentric with a radial offset from the longitudinal axis 10A, wherein in the present example a radial extension of the second section 22 starting from the longitudinal axis 10A is greater than a radial extension of the first section 18. In order to hold the tappet 12 in a predetermined position relative to the crankcase 16, the second section 22 is received in a recess 24, in particular a groove in the tappet 12, wherein a rotation or an adjustment of the angular position of the positioning screw 10 due to the second section 22 enables a height adjustment of the tappet 12 in order to compensate for position tolerances.

[0032] By adjusting the height or the translational movement of the roller tappet 12 due to a rotation of the positioning screw 10, a contact of the roller of the roller tappet 12 to the track of a cam 26 is optimized accordingly, so that, on the one hand, a predetermined guide for the roller tappet 12 is provided by a corresponding rotation of the camshaft 28 and, on the other hand, a twisting of the roller tappet 12 is largely avoided by the improved contact.

[0033] In order to adjust the angular position of the positioning screw 10, the first section 18 in the present example has an external thread 30, which engages with an internal thread in the bore 20 of the crankcase 16. In this way, the external thread 30 also provides a bearing for the tappet 12. The first section 18 also has a stop 32, which engages with an edge or wall surface of the bore 20 when the positioning screw 10 is fully inserted or screwed into the crankcase 16 or into the bore 20. In this way, it can be ensured that the positioning screw 10 is positioned correctly in length and that the second section 22, which preferably forms a tip of the positioning screw 10, is correspondingly received in the recess 24.The positioning screw 10 can then be turned, for example, by half a turn to allow any necessary height adjustment of the plunger 12.

[0034] Furthermore, the first section 18 comprises a receptacle for a fastening means 34, which is shown here in the form of a nut. The receptacle is arranged at an end region of the first section 18 longitudinally opposite the second section 22 and, when the positioning screw 10 is inserted, is located outside the crankcase 16. Once the height of the tappet 12 has been sufficiently adjusted, the positioning screw 10 is tightened accordingly using the nut.

[0035] In order to rotate the positioning screw 10, an actuating element 36 can also be provided at the outer end, for example in the form of a recess for inserting a screwdriver.

[0036] In the Figures 2A and 2B alternative embodiments of the positioning screw 10 according to the invention are shown in a cross-section and a plan view in the direction of the longitudinal axis 10A. In both embodiments, the second section 22 is arranged as an eccentric with a radial offset to the longitudinal axis 10A and, in the present case, without optional inclination in the radial direction. Figure 2A However, the second section 22 is arranged with a partial offset to the cross section of the first section 18, so that a radial extension of the second section 22 starting from the longitudinal axis 10A is greater than a radial extension of the first section 18. In Figure 2BHowever, a cross-section of the second section 22 is arranged to completely overlap a cross-section of the first section 18. Due to the asymmetry in both embodiments, or rather the non-concentric arrangement of the second section 22 and the first section 18, a change in the height position of the plunger 12 can be achieved by rotating the positioning screw 10, which is essentially determined by the offset of the second section 22 relative to the longitudinal axis 10A.

[0037] Where applicable, all individual features shown in the embodiments may be combined and / or exchanged with one another without departing from the scope of the invention. List of reference symbols

[0038] 10Positioning screw 10A Longitudinal axis 12 Tappet 14 Receptacle 16 Crankcase 18First section 20Through hole 22Second section 24Recess 26Cam 28Camshaft 30External thread 32Stop 34Fastener 36Actuator

Claims

1. Positioning screw (10) for a tappet (12) of an internal combustion engine, in particular a gas engine, comprising a first section (18) which is elongated and defines a longitudinal axis (10A) of the positioning screw (10), wherein the first section (18) is designed to be received at least partially in a through-bore (20) of a crankcase (16) in the assembled state, and a second section (22) which is designed to engage with a recess (24) of the tappet (12) in the assembled state of the positioning screw (10) and in the received state of the tappet (12) in the crankcase (16), wherein the second section (22) is designed with a radial offset to the longitudinal axis (10A).

2. Positioning screw (10) according to claim 1, wherein the second portion (22) extends from an end region of the first portion (18) in the longitudinal direction and / or in the radial direction.

3. Positioning screw (10) according to claim 1 or 2, wherein a radial extension of the second portion (22) starting from the longitudinal axis (10A) is greater than a radial extension of the first portion (18).

4. Positioning screw (10) according to claim 1 or 2, wherein a cross section of the second portion (22) completely overlaps with a cross section of the first portion (18).

5. Positioning screw (10) according to one of the preceding claims, wherein the second portion (22) defines a free end and / or a tip of the positioning screw (10).

6. Positioning screw (10) according to one of the preceding claims, wherein the first portion (18) is pin-shaped and / or cylindrical and / or has a circular cross-section.

7. Positioning screw (10) according to one of the preceding claims, wherein the second portion (22) is pin-shaped and / or cylindrical and / or has a circular cross-section.

8. Positioning screw (10) according to one of the preceding claims, wherein the first portion (18) has an external thread (30) and wherein a radial extension of the second portion (22) starting from the longitudinal axis (10A) is smaller than a radial extension of the external thread (30).

9. Positioning screw (10) according to one of the preceding claims, wherein the first portion (18) has a stop (32) which is designed to engage with a wall of the crankcase (16) in the at least partially assembled state of the positioning screw (10).

10. Positioning screw (10) according to one of the preceding claims, wherein the first section (18) has, in a region longitudinally opposite the second section (22), a receptacle for a fastening means (34), which is arranged such that the fastening means (34) engages with a wall of the crankcase (16) in the received state.

11. A method for positioning a tappet of an internal combustion engine, comprising the steps of: - providing a positioning screw according to one of the preceding claims; - positioning the tappet on an opening ramp or closing ramp of a cam of the internal combustion engine and turning the positioning screw into a through-bore of the tappet to a first position with a predetermined torque; - positioning the tappet on the respective other ramp of the cam and turning the positioning screw into the through-bore of the tappet to a second position with the predetermined torque; - tightening the positioning screw in a third position between the first position and the second position.

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