KR20070122214A - External part of a switchable bucket tappet - Google Patents

Abstract

The invention relates to an external part (1) of a switchable bucket tappet, whereby the principle elements thereof, such as the webs (9, 18) and channels (13, 14a) are produced by metal injection moulding (MIM) for forming an individual piece in the vicinity of the end. As a result, the external part (1) can be produced in an economical manner and metal-cutting post-work is essentially unnecessary. Also, a separate sheet metal part for forming hydraulic agent channels is not required.

Description

EXTERNAL PART OF A SWITCHABLE BUCKET TAPPET}

The present invention relates to an outer portion of a switchable valve tappet for a valve train of an engine, comprising a hollow cylindrical outer shroud that is receivable by a guide bore of the cylinder head of the engine by an envelope, the outer shroud being the base as a cam operating surface. Guide bushes limited in front of their cam side by and extending in a direction away from the cam from the inner edge of the base extend with respect to the inner part of the valve tappet, the guard plate with the guide bush having a diameter through the outer part. Connected to the guide bush by a first web extending axially at the bottom of the base, in which the web is equipped with a guide bore for at least sliding connection means, the first web being in the shell of the outer shroud. Hydraulic medium supply bore fed from the first channel starting from the first inlet It is cut in the radial side in the axial direction.

The outer part for the switchable valve tappet is described in DE 43 14 619 A1, in which a plunger is considered a general type. The outer part for the plunger is produced, for example, by extrusion technology or by cutting. It is recognized that inside the outer part an additional plate part is provided as a connecting medium and a hydraulic stroke compensation element for the formation of a hydraulic medium channel for the conduit of the outer part. The plate part shall be consumably welded and sealed there with the inner skin of the outer protective plate of the outer part. Cutting rework of the endothelium is necessary to ensure sealing. Overall the manufacturing cost for the outer part is unnecessarily high, which leads to an unnecessarily high cost in mass production.

It is therefore an object of the present invention to achieve the external part of the form and to eliminate the disadvantages cited.

According to the invention, this object is achieved by manufacturing the outer part in a single piece by means of a metal injection molding method (MIM) or precision casting.

This effectively eliminates the above disadvantages. The outer part is preferably provided as a whole part, such as a web, a channel or the like, by a metal injection molding method or by precision casting.

In the case of the above-described metal injection molding method (MIM), which is well known to those skilled in the art, the freedom of plastic injection molding in component construction is combined with the advantages of powder metallurgy, i.e., wide material selectivity with very small tolerances. Particularly preferably, back cutouts, hollow chambers, screws and the like can be made at one time during the metal injection molding. Those skilled in the art here employ slide techniques and / or core extraction techniques.

Also in the metal injection method, it can be produced by conventional plastic injection molding machine. Cutting rework is omitted or minimized. It is also clear that the outer part is provided without cracking after the injection molding technical completion and contains good rigidity. If desired, a wall thickness of preferably 1 mm or less may be provided, which affects the vibrating valve drive over the entire size of the outer part.

 Basically, in the manufacture of the outer part, a lost core, which can be made of plastic, for example, can also be produced, and the removal of the core also takes place by thermal decomposition and evaporation.

The manufacturing cost is reduced by the cutting reworking step and the removal of the steel sheet part.

In a refinement of the invention an inner part of the switchable tappet is arranged inside the guide bush, and the valve tappet is provided with a hydraulic play compensation device. In order to provide a hydraulic medium, another inlet of the outer sheath of the outer sheath is installed opposite the diameter of the first inlet of the sheath of the outer sheath, through which the hydraulic medium can be guided to the play compensation element. The two inlets face away from the radius of the other web, the first web having the guide bore cut in a plane, preferably at right angles.

In a specific embodiment of the invention a ring portion formed as a stop for at least one lost motion spring may be mounted to the web from below. The outer edge of the ring portion is provided with a collar spaced away from the cam for better guidance of the spring.

According to another preferred configuration of the invention the first channel from the first inlet extends obliquely through the valve tappet together with the connecting means before the guide bore. The other channel can be molded directly into the other web so that the other channel intersects the bore of the guide bush perpendicularly to the axial line of the outer part.

It is preferred when the longitudinal groove is provided in the shell of the outer shroud at each inlet. The longitudinal grooves should be in communication with the conduits which respectively cross the guide bores of the cylinder head. Thus the first and second channels are always under hydraulic medium operation or expensive longitudinal grooves need not be used in the guide bore of the cylinder head.

The hydraulic medium can preferably be guided directly to at least the connecting means and the hydraulic tolerance compensating element, with the removal of the storage space presented in the background. However, it is also possible for each sector type storage space for the hydraulic medium to be provided at the bottom of the base, respectively.

In addition, tabs protruding in the cam direction are provided on the shell of the outer shroud from the front face and at the sides of each inlet. Due to the tab, a sufficiently high sealing clearance for the hydraulic medium guided through the cylinder head is given in the guide bore of the outer part during the immersion movement of the outer part. Therefore, hydraulic medium loss is reduced.

It is also proposed to lower the base of the outer part to the outside of the cam drive face. This has the advantage of, for example, external partial reinforcement. The skilled person can thus install the outlet opening in a suitable, preferably metal injection molding method in the base region of the groove in order to prevent the accumulation of hydraulic medium in the achieved roof shaped groove.

The base of the outer portion can be made cylindrically arcuate in the cam movement direction to produce a smaller diameter of the outer portion. One skilled in the art chooses the width of the recesses created so that in any case the cam contact is implemented in the full width of the body.

Preferably the base of the outer part can be contacted by a large stroke cam extending from both sides of the guide bush.

 Furthermore, the outer part for the switchable valve tappet with the lowered base in the inclined form specified above is provided or contemplated not to be achieved by metal injection molding methods, but by conventional extrusion or extraction techniques or by cutting. can see. A slide set or at least slide known as a connecting medium is provided, the slide set or slide being preferably displaced in one direction by hydraulic medium pressure and in another direction at least by the force of a mechanical spring.

Hereinafter, the present invention is described in more detail with reference to the drawings.

1 is a spatial view of the outer part according to the invention.

2 is a longitudinal sectional view of an outer portion along another web;

3 is another view of the outer part with a separate ring part as a spring system.

4 is a longitudinal sectional view of the outer portion oblique from the bottom in the area of another web;

5 is a ring portion shown in FIG.

1 to 4 show the outer part 1 for the switchable valve tappet, wherein the entire part of the valve tappet is preferably provided by a metal injection molding method (MIM) or alternatively by precision casting. .

The outer part 1 has a hollow cylindrical outer protective plate 2 which can be arranged in the receiving bore of the cylinder head via the outer shell 3. The outer protective plate 2 is bounded at its cam side front face 4 by the base 5 as a cylindrical arcuate cam face in the cam movement direction.

The guide bush 7 extends with the bore 8 in a direction away from the cam from the inner edge 6 of the base 5. Within the bore 8 an internal part of the switchable valve tappet can be arranged. However, the switchable valve tappet may have a hydraulic actuation compensation device but is not required to have it.

The first web 9 extends axially from the bottom of the base 5 in diameter through the outer part 1. The first web 9 has a guide bore 10, in which the connecting means can be arranged hydraulically driven in at least the displacement direction. In this case, as shown in FIG. 3, the guide bore 10 is cut by the first channel 13 for the hydraulic medium on the radial side 11. The first channel starts from the first inlet 14 in the shell of the outer shroud 2 and is integrally manufactured by the metal injection molding method. The first channel 13 extends obliquely in the direction of the guide bore 10 through the outer part 1.

In addition, the first inlet 14 is in flow connection with the longitudinal groove 16 in the shell 3 of the outer shroud 2. Similarly, the second inlet 15 facing in diameter with the first inlet 14 is connected with the other longitudinal groove 17. Each longitudinal groove 16, 17 cutting the guide bore of the cylinder head for the outer part 1 is in communication with a supply bore for the hydraulic medium. Thus, hydraulic medium supply is possible over all stroke stages of the outer part 1.

The second channel 14a shown in FIGS. 2 and 4 starts directly from the second inlet 15 through another web 18. The second inlet 15 is used to join the bore 8 radially inward and to supply the hydraulic medium arranged in the inner part, not shown, to the hydraulic stroke compensation element. The second channel 14a is preferably likewise formed during the metal injection molding process.

On the webs 9, 18 that are "cut" vertically in the plan view, the ring portion 27 as seen in FIG. 5 is arranged so as not to tilt downward. The ring portion 27 has a collar 29 protruding from the outer edge 28, spaced away from the cam (the ring portion can rotate according to FIG. 5). A revolving spring or spring package can be applied to the ring portion 5. The collar 29 is used for centering the resilient spring.

The base 5 shown lowered outside the cam drive plane is another important part of the outer part 1 described herein. Two bow-shaped upper edges 19, 20 of the base 5, which also run through the outer part 1, face equidistantly to the longitudinal central plane (FIG. 1). The upper edge is formed with two concave portions 21 and 22 facing in diameter as the minor guide bush 7 is cut off and dropped into another inclined web 18, for example from FIG. 1. As the "tilt" of the base 5 has the effect of being reinforced to the entire outer part 1, the outer part 1 may in some cases be thinner.

As shown in the other figures, two tabs 23, 24 on the side of each inlet 14, 15 protrude outward through the base 5 in the shell 3. The conduit in the guide bore of the cylinder head is "sealed" in the direction away from the cam during the exchange movement of the outer part 1.

Thus, preferably the channels 13, 14a in which the outer part 1 produced by the metal injection molding method (MIM) are formed in one piece and the webs 9, 18 intersected in the sealed extension are compared with the background art. It is relatively inexpensive. In most cases, additional measures such as grinding rework or welding can be abandoned. It is of course also possible for the inner part which can be extended in the guide bush 7 to be manufactured by metal injection molding.

<Drawing code list>

1: outer part

2: outer shroud

3: outer shell

4: end

5: donation

6: inner edge

7: guide bush

8: bore

9: first web

10: guide bore

11: radial side

12; Supply bore

13: first channel

14: first inlet

14a: second channel

15: second inlet

16: longitudinal groove

17: longitudinal groove

18: other web

19: upper edge

20: upper edge

21: recess

22: recess

23: tab

24: tab

25: lower side

26: lower side

27: ring part

28: outer edge

28: collar

Claims (11)

An outer part (1) of a switchable valve tappet for an engine valve train, having a hollow cylindrical outer shroud (2) which is receivable through the sheath (3) as a guide bore of the cylinder head of the engine, said outer shroud (2) Is limited at its cam side front face 4 by the base 5 as the cam operating surface, and from the inner edge 6 of the base 5, the guide bush 7 extending in a direction away from the cam has a bore ( 8) a protective plate 2 extending with respect to the inner part of the valve tappet, with a guide bush 7 extending in diameter through the outer part 1 and extending axially from the bottom of the base; It is connected to the guide bush 7 by a web 9, in which a guide bore 10 for at least sliding connection means is mounted, the first web 9 being an outer shell of the outer protective plate 2. From the first channel 13 starting from the first inlet in (3) In the outer part 1 of the switchable valve tappet 1 which is axially cut at the radial side 11 of the hydraulic medium supply bore 12 for the hydraulic medium to be fed, The outer part of the switchable valve tappet, which is formed in one piece by a metal injection molding method (MIM) or fine injection. 2. A second channel (14a) integrally connected with the outer portion extends in a circumferential direction with respect to the first channel (13) and the first web (9), and the second channel extends in an outer protective plate ( 2) The outside of the switchable valve tappet, which is started in the second inlet 15 and the bore 8 of the guide bush 7 is cut for the supply of a hydraulic stroke compensating element which can be arranged in the inner part. part. 3. The first and second inlets 14, 15 are arranged opposite in diameter at the outer shroud 2, and the connecting lines of the first and second inlets have a guide bore 10. The outer part of the switchable valve tappet, characterized in that it intersects one web 9 at least approximately at right angles. The method according to claim 1 or 2, wherein when referring to claim 1, the first inlet portion 14 is connected to the longitudinal groove 16 in the shell 3 of the outer shroud, or If cited, the outer part of the switchable valve tappet, characterized in that at least one of the inlets 14, 15 is in communication with the longitudinal grooves 16, 17 in the shell 3 of the outer shroud 2. 4. An outer portion (18) according to claim 3, wherein an outer portion (18) is formed spaced apart in the axial direction of the base (5) and extends in diameter through the outer portion (1) and is integrally connected with the web (18). At or one of the inlets 14, 15 extends radially outward in the peripheral region of the outer part, respectively, and the first channel 13 is obliquely or bent from its first inlet 14. 1 extends from the inlet 14 into the web 9 with the guide bore 10 from the radial side 11, the second channel 14a extending from the second inlet 15 of the other web 18. An outer portion of the switchable valve tappet, which is arranged in a corresponding segment. The outer part 1 is rotatably mounted in the guide bore of the outer part in the cylinder head, so that the other web 18 extends on the base 5 parallel to the cam movement direction. The base 5 has a bow-shaped upper edge 19, 20 extending equidistantly to two longitudinal intermediate faces via the outer part 1, the upper edge opposite the cam onto the other web 18. The outer part of the switchable valve tappet, characterized in that it is inclined in the form of a roof for the formation of two recesses 21, 22 which proceeds to. 7. The bow-shaped upper edges 19, 20 of the recesses 21, 22 comprise a substantially constant spacing in the region of the diameter of the guide bush 7 or slightly intersect the guide bush. Outer part of switchable valve tappet. The tabs 23, 24 according to claim 1, wherein the outer shell 3 of the outer shroud 2 is integrally connected with the outer shell at the periphery where the inlets 14, 15 are arranged. An outer portion of the switchable valve tappet, which extends onto the base (5) by means of. 6. The ring portion 27 extends as a rest stop for the lost motion spring in the lower portions 25, 26 of the webs 9, 18, wherein the ring portion 27 optionally has a ring portion. The outer part of the switchable valve tappet, characterized in that the collar 29 is spaced apart from the outer edge 28 of the cam in the opposite direction. 10. The outer part of the switchable valve tappet according to claim 1, wherein the base (5) has a cylindrical arcuate extension in the cam movement direction. The outer part of the switchable valve tappet according to any one of the preceding claims, characterized in that a substantially constant wall thickness is provided on the outer part (1).

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