Hydraulic support element for a valve train of an internal combustion engine

Abstract

A hydraulic support element (1) for a valve train of an internal combustion engine, which support element is free of pressure oil connections and which is seated directly in a smooth-walled, unstepped receiving bore (4) of a cylinder head (5) via an outer casing (2) of its housing (3), and in the bore (6) of which a pressure piston (7) is guided with its outer surface (8) which is axially movable relative thereto, said pressure piston projecting with its head (16) serving to support a rocker arm over an edge (9) of the housing (3) and a planar upper side (10) of the cylinder head (5) at least in the opening region of the receiving bore (4), wherein axially below a base (11) of the pressure piston (7) remote from the head, between said base and a housing base (12), there is a high-pressure chamber (13) for hydraulic fluid, which can be supplied with hydraulic fluid via a check valve (14) on the base (11) from a reservoir (15) enclosed by the pressure piston (7),wherein an extension spring (17) located in the high-pressure chamber (13) and supported at the other end against the housing base (12) acts against the bottom (11) of the pressure piston (7), and an extension movement of the pressure piston (7) is limited by stop means (24) extending radially between the pressure piston (7) and the housing (3), wherein for the supply of hydraulic fluid into the storage chamber (15) of the pressure piston (7), a first pre-accumulator (22) for the hydraulic fluid is provided, which is present as a collecting channel (18) for spray oil / oil mist intersecting the top side (10) of the cylinder head (5) as a circumferential annular space in the outer casing (2) of the housing (3), which collecting channel (18) opens into at least one radial passage (20) in the housing (3) via a section (19) lying low on the receiving bore side, wherein a second pre-accumulator (23) is provided for the hydraulic fluid,formed by an annular recess in the bore (6) of the housing (3) and connected via the at least one radial passage (20) in the housing (3) to the first pre-accumulator (22), which second pre-accumulator (23) is in fluid communication with at least one radial opening (21) in the pressure piston (7) to the storage chamber (15) thereof, characterized in that the top side (10) of the cylinder head (5), which is flat at least in the mouth region of the receiving bore (4), is a flat top side (10) of the cylinder head (5), wherein the collecting channel (18) forming the first pre-accumulator (22) is an annular collecting channel (18) in the outer casing (2) of the housing (3), starting from the upper edge (9) thereof, and wherein the stop means (24) limit the extension movement of the pressure piston (7) from the housing (3) in such a way that, at the maximum extension position of the pressure piston (7), its radial opening (21) is further away from the head than the Radial passage (20) in the housing (3).,

Description

[0001] The invention relates to a hydraulic support element for a valve train of an internal combustion engine, which support element is free of pressure oil connection and which is seated directly in a smooth-walled, unstepped receiving bore of a cylinder head via an outer casing of its housing and in whose bore a pressure piston, which is axially movable relative to the pressure piston, is guided with its casing surface, which piston projects with its head serving as a bearing for a rocker arm over an edge of the housing and a flat upper side of the cylinder head, at least in the mouth area of ​​the receiving bore, wherein axially below a base of the pressure piston remote from the head, between the latter and a housing base, there is a high-pressure chamber for hydraulic fluid, which can be supplied with hydraulic fluid via a check valve on the base from a storage chamber enclosed by the pressure piston,wherein an extension spring located in the high-pressure chamber and supported at the other end against the housing bottom acts against the bottom of the pressure piston, and an extension movement of the pressure piston is limited by stop means extending radially between the pressure piston and the housing, wherein a first pre-accumulator for the hydraulic fluid is provided to supply hydraulic fluid into the reservoir of the pressure piston, which first pre-accumulator is provided as a collecting channel for spray oil / oil mist intersecting the top of the cylinder head as a circumferential annular space in the outer casing of the housing, which collecting channel opens into at least one radial passage in the housing via a section lying low on the receiving bore side, wherein a second pre-accumulator for the hydraulic fluid is provided, formed by an annular recess in the bore of the housing and connected to the first pre-accumulator via the at least one radial passage in the housing,which second pre-storage device is in fluid communication with at least one radial opening in the pressure piston to its storage chamber.,

[0002] As part of the further optimization of pressurized oil circuits in internal combustion engines, key words include "reducing oil pump performance" and "downsizing the oil pump," hydraulic support elements are being developed for rocker arm valve trains that are no longer connected to the internal combustion engine's pressurized oil circuit. Such elements, once initially filled, utilize only spray oil or oil mist from the valve control area above the cylinder head for their supply.

[0003] A support element installed in a cylinder head without a pressure oil connection is described in DE 10 2014 214 383 A1. This can be seen, for example, in Fig. 4 in conjunction with Fig. 1, this element protrudes with its head into a trough-shaped recess in the cylinder head. This recess serves as a reservoir. From this, the hydraulic fluid is directed downwards via two collecting channels located diametrically opposite one another on the outer surface of the support element's housing to respective radial passages in the housing.

[0004] It is determined that the required recess for each element requires significant modifications to existing cylinder heads, which significantly increases the cost of the internal combustion engine in mass production. Furthermore, the required recess unnecessarily weakens the cylinder head and poses a risk of collision with the cylinder head's ports. Furthermore, it can be seen (see Fig.2) that due to the relatively low radial passage in the housing and the radial opening in the pressure piston which is located higher in comparison, when the pressure piston is in the extended position shown from the housing (transport stop), the pre-filled storage space in the pressure piston empties to the level of a lower edge of its radial opening.

[0005] JP 2014 - 70 559 A discloses a hydraulically self-contained support element. Its housing, with a funnel-shaped oil collection collar, protrudes above the top of the cylinder head.

[0006] JP 2009 - 19 584 A shows a hydraulic support element, also without an external oil supply, whose pressure piston extends above the top of the cylinder head. The support element is surrounded on the head side by a depression that forms an oil storage pocket.

[0007] Another support element without an external pressure oil supply is shown in DE 10 2016 200 625 A1. In this case, the housing is surrounded by a separate sleeve with oil storage chambers. It is clear that the support element would therefore have to be modified extensively, especially since the cylinder head mounting bore also needs to be enlarged.

[0008] The task is to create a hydraulic support element in a cylinder head that does not require an external pressure oil supply and does not require major modifications to existing designs.

[0009] According to the invention, this object is achieved in that the top side of the cylinder head, which is flat at least in the mouth region of the receiving bore, is a flat top side of the cylinder head, wherein the collecting channel forming the first pre-accumulator is an annular collecting channel in the outer shell of the housing, starting from its upper edge, and wherein the stop means limit the extension movement of the pressure piston from the housing in such a way that, when the pressure piston is in the maximum extension position, its radial opening is further away from the head than the radial passage in the housing.

[0010] This results in a support element installed in a cylinder head that is free of pressure oil connections and does not suffer from the disadvantages mentioned above. In this case, a previously used support element can largely be used without modifying the cylinder head. A pressure oil channel previously present in the cylinder head to the respective support element simply remains as a blind channel. Due to the two pre-accumulators on / in the virtually unchanged support element, it is possible to direct a sufficient quantity of spray oil, etc., into the interior of the component for proper clearance compensation and to store it there. A support element that is also unchanged in terms of its outer diameter can be installed, or its mounting bore in the cylinder head can be left unchanged. At the same time, the pressure piston of the support element should be held in its maximum extended position by a stop device such as an internal snap ring / circlip.According to the invention, the radial opening is located below the high radial passage of the housing, so that a comparatively high column of hydraulic fluid in the support element is prevented from leaking out, which is important, for example, after an initial filling and subsequent transport.

[0011] To increase the volume of both pre-storage units, the wall area surrounding them radially, or one of them, can be made thinner.

[0012] A further measure for improved accumulation of hydraulic fluid in the reservoir of the pressure piston is the subject of a further subclaim. Accordingly, a portion of hydraulic fluid forced from the high-pressure chamber during a high-pressure phase through a leakage gap between the pressure piston and the housing is to be returned directly to the reservoir via a low-lying deflection opening. In a two-part pressure piston, this deflection opening can be located in the area of ​​the overlapping ends of the two axial sections and can be designed, for example, as one or more crown-like openings.

[0013] The invention is evident from the drawing. The single figure shows a longitudinal section through a support element 1 without an external pressure oil supply.

[0014] It can be seen that the support element 1 is seated via an outer shell 2 of its pot-like housing 3 in a blind hole-like, smooth-walled, unstepped receiving bore 4 of the cylinder head 5. A pressure piston 7, which is axially movable within this bore, is guided with its outer surface 8 in a bore 6 of the housing 3. The latter, with its head 16 projecting beyond an edge 9 of the housing 3 and a flat upper side 10 of the cylinder head 5, serves as a one-ended, pivotable mounting of a rocker arm. The housing 3 can also be flush with an upper side 10 of the cylinder head 5 or be slightly lower. If the latter were positioned lower, this would represent yet another oil reservoir (see below).

[0015] A high-pressure chamber 13 for hydraulic fluid is located axially below a base 11 of the pressure piston 7, remote from the head 16, between the base 11 and a housing base 12. This chamber can be supplied with hydraulic fluid via a check valve 14 on the base 11 from a reservoir 15 enclosed by the pressure piston 7 below its head 16.

[0016] The only hydraulic fluid "collected" is spray oil / oil mist from the area above the top side 10 of the cylinder head 5, which then flows under the influence of gravity into the reservoir 15 of the pressure piston 7. For this purpose, an annular collecting channel 18 is provided in the outer casing 2 of the housing 3, starting from its upper edge 9, as the first pre-accumulator 22. The lower section 19 of the collecting channel 18 is connected to a radial passage 20 in the housing 3. From the radial passage 20 (bore), the hydraulic fluid is passed downwards into a second annular pre-accumulator 23 in the bore 6 of the housing 3. The second pre-accumulator 23, in turn, is in fluid communication with a radial opening 21, designed as a bore, in the pressure piston 7, which leads directly into the reservoir 15 of the pressure piston 7.

[0017] An extension spring 17 is installed in the high-pressure chamber 13. This spring is clamped between the base 11 of the pressure piston 7 and the housing base 12. To limit the extension movement of the pressure piston 7 out of the housing 3 (transport lock), the pressure piston 7 has a retaining ring seated in an annular groove in its outer surface 8 as a stop means 24. In the event of a stop, the radial opening 21 of the pressure piston 7 would be located lower than the radial passage 20 in the housing 2.

[0018] The pressure piston 7 consists of two separate components, an upper axial section 27 and a lower axial section 26, which are positioned on top of each other with their faces 29, 28. Deflection openings 25 for the hydraulic fluid are provided between the faces 29, 28. List of reference numbers 1 support element 2 outer jacket 3 housings 4 mounting hole 5 cylinder head 6 Hole 7 pressure pistons 8 Shell surface 9 Edge 10 Top 11 Floor 12 Case back 13 High-pressure room 14 Check valve 15 Storage room 16 heads 17 Ejection spring 18 Collecting channel Section 19 20 Radial passage 21 Radial opening 22 first pre-storage 23 second pre-storage 24 lifting gear, retaining ring 25 Deflection opening 26 lower axial section 27 upper axial section 28 forehead 29 Forehead

Claims

[1] A hydraulic support element (1) for a valve train of an internal combustion engine, which support element is free of pressure oil connections and which is seated directly in a smooth-walled, unstepped receiving bore (4) of a cylinder head (5) via an outer casing (2) of its housing (3), and in the bore (6) of which a pressure piston (7) is guided with its casing surface (8) which is axially movable relative to the housing (3), said pressure piston projecting with its head (16) serving to support a rocker arm over an edge (9) of the housing (3) and over a top surface (10) of the cylinder head (5) which is flat at least in the opening region of the receiving bore (4), wherein axially below a bottom (11) of the pressure piston (7) remote from the head, between the latter and a housing bottom (12), there is a high-pressure chamber (13) for hydraulic fluid, which can be supplied with hydraulic fluid via a check valve (14) on the bottom (11) from a storage chamber (15) enclosed by the pressure piston (7),wherein an extension spring (17) located in the high-pressure chamber (13) and supported at the other end against the housing base (12) acts against the bottom (11) of the pressure piston (7), and an extension movement of the pressure piston (7) is limited by stop means (24) extending radially between the pressure piston (7) and the housing (3), wherein, for the supply of hydraulic fluid into the storage chamber (15) of the pressure piston (7), a first pre-accumulator (22) for the hydraulic fluid is provided, which is present as a collecting channel (18) for spray oil / oil mist intersecting the top side (10) of the cylinder head (5) as a circumferential annular space in the outer casing (2) of the housing (3), which collecting channel (18) opens into at least one radial passage (20) in the housing (3) via a section (19) lying low on the receiving bore side, wherein a second pre-accumulator (23) is provided for the hydraulic fluid,formed by an annular recess in the bore (6) of the housing (3) and connected via the at least one radial passage (20) in the housing (3) to the first pre-accumulator (22), which second pre-accumulator (23) is in fluid communication with at least one radial opening (21) in the pressure piston (7) to its storage chamber (15), , characterized by in that the top side (10) of the cylinder head (5) which is flat at least in the mouth region of the receiving bore (4) is a flat top side (10) of the cylinder head (5), wherein the collecting channel (18) forming the first pre-storage device (22) is an annular collecting channel (18) in the outer casing (2) of the housing (3), starting from the upper edge (9) thereof, and wherein the stop means (24) limit the extension movement of the pressure piston (7) from the housing (3) in such a way that when the pressure piston (7) is in the maximum extension position, its radial opening (21) is further away from the head than the radial passage (20) in the housing (3). [2] Support element according to claim 1, characterized bythat the radial passage (20), measured from the edge (9) of the housing (2), is not deeper than ¼ of a length of the housing (2). [3] Support element according to claim 1, characterized by that at least one radially continuous deflection opening (25) for hydraulic medium is applied in the pressure piston (7), which extends in an axial section between its base (11) and the radial opening (21). [4] Support element according to claim 3, characterized by that the pressure piston (7) is constructed from a lower axial section (26) with the base (11) and a separate upper axial section (27) with the head (16), wherein the at least one deflection opening (25) is located between their superimposed ends (28, 29).

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