Push rod of a variable-lift valve train of an internal combustion engine

Abstract

Proposed is a push rod of a variable-lift valve train of an internal combustion engine, an adjusting finger projecting from the push rod, the adjusting finger being used to load a coupling mechanism of a switchable valve train component, the push rod having, on the one hand, a contact surface for an actuator to move the push rod forward and, on the other hand, a carrier plate with a damping strut, the damping strut consisting of a guide bushing fixed in a bore of the carrier plate, the guide bushing being telescopically inserted into a guide cylinder, the guide cylinder projecting beyond a rear wall of the carrier plate by means of a rod section, a helical compression spring being clamped between the rear wall and an annular flange of the rod section, the rod section having a clamping surface on a free end of its front end for bearing on a mating contour of the cylinder head, wherein the bore of the carrier plate has at least two opposite spanner faces, the guide bushing being pressed against the spanner faces via an annular section of its outer shell.

Description

Technical Field

[0001] This invention relates to a pushrod for a variable-lift valve train of an internal combustion engine, from which an adjusting finger extends. The pushrod is used to load coupling mechanisms of switchable valve train components. The pushrod has, on one hand, a contact surface for an actuator to move it forward, and on the other hand, a support plate with a buffer strut to move it backward. The buffer strut is formed by a guide bushing fixedly located in a hole in the support plate. The guide bushing is telescopically inserted into a guide cylinder, which, when viewed in the forward direction, extends from the rear wall of the support plate by means of a rod section surrounded by at least one helical compression spring. The helical compression spring is clamped between the rear wall and an annular flange of the rod section. The rod section has a clamping surface at its free end for support on a mating profile of the cylinder head. Background Technology

[0002] From DE 10 2019 102 765 B3, Figure 4 A buffer strut with a variable-lift valve timing mechanism and a support plate is described, also known as an electronic rocker arm valve timing mechanism. Here, the guide bushing in the hole of the support plate is secured by a separate clip on the front wall of the support plate. Furthermore, the guide cylinder of the buffer strut also has a separate clip on its housing in the section located before the front wall of the support plate, which provides extension restriction for the guide cylinder.

[0003] Also refer to DE 10 2017 101 792 B4. This document provides a general description of a variable lift valve train with a pushrod. Summary of the Invention

[0004] The aim is to design a push rod whose reset unit (a support plate with a buffer strut) requires fewer components and can be easily installed.

[0005] According to the present invention, the objective is achieved as follows: the bore of the bearing plate has at least two opposing wrench faces. The guide bushing is pressed against the wrench face via the annular section of its housing.

[0006] Therefore, the following push rod is provided, which is very easy to install and requires relatively few components in the area of ​​its reset unit. In mass production, this means a significant cost reduction. In particular, exactly two faces are considered as wrench faces in the holes of the support plate, which can also be referred to as bowstring-shaped flattened portions. However, it is conceivable that a large number of two or an odd number of wrench faces are feasible. Corrugated or serrated profiles in the holes are also considered. It is also possible to slot the holes of the support plate if necessary.

[0007] In particular, levers, such as tow bars, are considered as switchable valve train components. This also includes rocker arms or rocker shanks, or support elements for tow bars.

[0008] According to a preferred design, the guide bushing has at least three annular segments on its outer shell: a first annular segment that presses against a hole in the support plate; a second annular segment with a larger diameter, through which the guide bushing rests against the rear wall of the support plate; and a third annular segment recessed relative to the second annular segment, the third annular segment being surrounded by a first end region of the helical compression spring, which is directly supported on the second annular segment. Therefore, the guide bushing has at least three annular segments, wherein the middle annular segment serves as a stop surface for the guide bushing on the support plate and simultaneously as a contact portion for the direct end of at least one helical compression spring.

[0009] According to another improvement, the first annular segment of the guide bushing has a cone on its outer end side, wherein the first annular segment is pressed against the flat portion of the hole in the support plate. The cone serves as an introduction aid for the guide bushing during installation.

[0010] Furthermore, it is proposed that the guide cylinder extend beyond the front wall of the support plate via a hollow end member, and that its outer end side is provided with a radially widened portion, for example, by pressing or flanging. This simplifies the extension limitation of the guide cylinder. Therefore, separate retaining rings and annular grooves are eliminated. If necessary, the widening measure can be completely eliminated, further reducing the cost of the push rod unit.

[0011] Furthermore, the rod section has an annular flange / diameter thickening at its free end front end with a clamping surface. This feature, like the third annular section on the other side of the guide bushing, serves as a guide and prevents bulging of the helical compression spring.

[0012] According to further details, the support plate protrudes from the push rod on one side of the adjusting finger. Here, the support plate can be bent from the push rod as a single piece or exist as a separately assembled component. Alternatively, the support plate can also extend laterally or "upright." The support plate can be located on the front end of the push rod, which, for example, is located away from the actuator. Attached Figure Description

[0013] Regarding the attached image:

[0014] Figure 1 A perspective view of the push rod section with a reset unit (a bearing plate with a buffer support) is shown.

[0015] Figure 2A longitudinal section of a buffer strut with guide bushings is shown;

[0016] Figure 3 The image "from the front" shows the carrier plate with the installed guide bushings.

[0017] Figure 4 A partial longitudinal section view of a guide bushing with a support plate is shown. Detailed Implementation

[0018] from Figure 1 The image shows the end section of the pushrod 1 of a variable-lift valve train for an internal combustion engine. Adjustment fingers 2 are suspended from the pushrod 1, one of which is shown exemplarily. These adjustment fingers 2 are used to load the coupling mechanism (lateral piston) of a switchable trailing rod. Also shown in view is an electric actuator for moving the pushrod 1 forward (in the retraction direction R of the coupling mechanism). V The contact surface 3 of the actuator. The electric actuator can also be placed, for example, on another longitudinal region of the push rod 1.

[0019] A support plate 4 with a buffer support 5 is suspended from the push rod 1 (see...). Figure 3 This is used to move push rod 1 backward (in the extension direction R of the coupling mechanism) when the electronic actuator is deactivated or switched to a low current. R The buffer support 5 is composed of a guide bushing 7, which is pressed into and held in place by a hole 6 in the support plate 4. The guide bushing is telescopically connected to a guide cylinder 8. To achieve compression, the hole 6 in the support plate 4 has two wrench faces 14 facing each other, one above and one below, in the installation position. The guide bushing 7 has three annular sections 15, 17, and 18, wherein the first annular section 15 forms a compression engagement with the wrench face 14 via its outer shell 16 (see...). Figure 3 ).

[0020] On the other hand, the buffer support 5 is formed by a rod segment 11, which extends substantially behind the rear wall 9 of the support plate 4 and is surrounded by a helical compression spring 10. The latter is clamped between the rear wall 9 and the annular flange 12 of the rod segment 11. To better guide the helical compression spring 10, the guide bushing 7 has a third annular segment 18, which is surrounded by a first end region 19 of the helical compression spring 10. The guide bushing 7 rests against the rear wall 9 of the support plate 4 by means of a disc-shaped second annular segment 17, on which the helical compression spring 10 is also directly supported (see...). Figure 4 ).

[0021] In addition, from Figure 2It can be best concluded that the rod section 11 of the buffer support 5, at its free end front end 28 away from the bearing plate 4, has a clamping surface 13 at the annular flange 12 for support on the mating profile of the cylinder head, such as the upright web. A radially widened portion 27 is provided axially forward of the annular flange 12, which also serves to guide the helical compression spring 10.

[0022] As from Figure 2 , 4 It can be concluded that the first annular segment 15 of the guide bushing 7 has a tapered end segment 21 in the direction toward its outer end side 20. The end segment simplifies the insertion of the guide bushing 7 into the hole 6 of the support plate 4 during installation.

[0023] also, Figure 2 As shown, the guide cylinder 8 extends from the front wall 23 of the support plate 4 via a hollow end member 22. Here, its outer end side 24 has a radially widened portion 25, which exists as an annular pressing portion. This measure serves, for example, to limit the extension of the guide cylinder 8 relative to the support plate 4 during the transport and mounting of the push rod 1 to the cylinder head.

[0024] List of reference numerals in the attached diagram:

[0025] 1) Push rod

[0026] 2) Adjustment finger

[0027] 3) Contact surface

[0028] 4) Support plate

[0029] 5) Buffer pillars

[0030] 6) Hole

[0031] 7) Guide bushing

[0032] 8) Guide cylinder

[0033] 9) Posterior wall

[0034] 10) Helical compression spring

[0035] 11) Pole section

[0036] 12) Annular flange

[0037] 13) Clamping surface

[0038] 14) Wrench face

[0039] 15) First ring section

[0040] 16) Outer shell

[0041] 17) Second ring section

[0042] 18) Third ring section

[0043] 19) First end region

[0044] 20) Outer end side

[0045] 21) End section

[0046] 22) End components

[0047] 23) Anterior wall

[0048] 24) Outer end side

[0049] 25) Radial widening section

[0050] 26) Second end region

[0051] 27) Radial widening section

[0052] 28) End front end

[0053] R V Move forward, retract.

[0054] R R backward movement direction

Claims

1. A push rod (1) of a variable lift valve train for an internal combustion engine, wherein adjusting fingers (2) extend from the push rod (1), the adjusting fingers being used to load coupling mechanisms of switchable valve train components, the push rod (1) having, on one hand, a contact surface (3) for an actuator to move the push rod forward (R). V On the other hand, it has a support plate (4) with a buffer support (5) to allow the push rod to move backward (R). R The buffer support (5) is composed of a guide bushing (7) fixedly located in a hole (6) in the bearing plate (4), the guide bushing being telescopically inserted into a guide cylinder (8), the guide cylinder moving forward (R... V The direction of observation is achieved by means of a rod segment (11) extending from the rear wall (9) of the bearing plate (4) surrounded by at least one helical compression spring (10), the helical compression spring (10) being clamped between the rear wall (9) and the annular flange (12) of the rod segment (11), the rod segment (11) having a clamping surface (13) on its free end front end (28) for support on the mating profile of the cylinder head. Its features are, The support plate (4) has at least two opposing wrench faces (14) in the hole (6), and the guide bushing (7) is pressed against the wrench faces via the annular section (15) of its outer shell (16).

2. The push rod according to claim 1, characterized in that, The guide bushing (7) has at least three annular segments (15, 17, 18) on its outer shell (16): a first annular segment (15) that is pressed against the hole (6) of the support plate (4); a second annular segment (17) with a larger diameter, through which the guide bushing (7) rests against the rear wall (9) of the support plate (4); and a third annular segment (18) that is recessed relative to the second annular segment (17), the third annular segment being surrounded by the first end region (19) of the helical compression spring (10), the helical compression spring being directly supported on the second annular segment (17).

3. The push rod according to claim 2, characterized in that, The first annular section (15) of the guide bushing (7) has a tapered end section (21) in the direction toward its outer end side (20).

4. The push rod according to claim 1, characterized in that, The guide cylinder (8) extends from the front wall (23) of the support plate (4) with a hollow end member (22), and its outer end side (24) is provided here via a radially widened portion (25) for restricting the movement of the guide cylinder relative to the support plate (4).

5. The push rod according to claim 4, characterized in that, The radially widened portion (25) exists as a pressing portion.

6. The push rod according to claim 1 or 4, characterized in that, The rod section (11) of the guide cylinder (8) has a radially widened portion (27) in front of the annular flange (12) surrounded by the second end region (26) of the helical compression spring (10).

7. The push rod according to claim 1, characterized in that, The support plate (4) exists as a tab that protrudes orthogonally from the push rod (1) on the side of the adjustment finger (2).

8. The push rod according to any one of claims 1-5, characterized in that, The corresponding switchable valve train components are lever-shaped cam followers or support elements or combinations thereof.

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