Hydraulic support element with a ring filter

Abstract

A hydraulic support element for a variable valve train of an internal combustion engine, which has a cylindrical pot-shaped housing and a hollow cylindrical piston guided for movement in this housing and whose inner end is supported by a compression spring on the base wall of the housing. The outer end extends past the housing and is formed as a hemispherical bearing head. The interior is divided into an inner supply pressure space and an outer switching pressure space that are connected by inlet openings in the cylindrical side walls of the housing and the piston with a cylinder head side supply pressure line and by a non-return valve to a high-pressure space enclosed between the inner end of the piston and the base wall of the housing, or to a cylinder head side switching pressure line and also by a central hole formed in the bearing head to a rocker arm side switching pressure channel. To prevent the entry of harmful particles into the supply pressure space and/or the switching pressure space of the piston, the piston has a ring-shaped recess in its cylindrical side wall in the area of the inlet openings on the outside in the radial direction, and a filter element constructed as a ring filter is inserted into the ring-shaped recess of the piston with an axial positive-fit connection.

Claims

1. A hydraulic support element for a variable valve train of an internal combustion engine, the hydraulic support element comprising: a cylindrical pot-shaped housing having a cylindrical side wall and a base wall; a hollow cylindrical piston guided for axial movement in said housing, the hollow cylindrical piston having a cylindrical side wall, an inner end and an outer end, the outer end extends past an outer edge of the housing and is constructed as a hemispherical bearing head; an interior of the hollow cylindrical piston is divided into an inner supply pressure space and an outer switching pressure space, the supply pressure space is connectable via inlet openings in the cylindrical side wall of the housing and the cylindrical side wall of the piston with a supply pressure line on a cylinder head side and is connectable via a non-return valve to a high pressure space enclosed between the inner end of the piston and the base wall of the housing, and the switching pressure space is connectable via inlet openings in the cylindrical side wall of the housing and the cylindrical side wall of the piston with a cylinder head side switching pressure line and also by via a central hole formed in the bearing head with a rocker arm side switching pressure channel, the piston has, in the cylindrical side wall in an area of the inlet openings leading into at least one of the supply pressure space or the switching pressure space, a ring-shaped recess radially on an outside thereof; a compression spring that acts on the inner end of the hollow cylindrical piston and is supported on the base wall of the housing; and, a filter element constructed as a ring filter that is open on a circumferential side is inserted axially with a positive fit connection into the ring-shaped recess of the piston.

2. The support element according to claim 1, wherein the ring filter comprises: a cylindrical filter screen that is open on a circumferential side; a filter frame surrounding the filter screen, the filter frame has two ring-shaped edge connectors that are open on the circumferential side and are arranged on axial outer edges of the filter screen, and two straight edge connectors arranged on circumferential-side ends of the filter screen between the ring-shaped edge connectors; and multiple support connectors arranged within the filter screen distributed on the circumferential side between the ring-shaped edge connectors.

3. The support element according to claim 2, wherein the straight edge connectors of the filter frame lie one above the other so as to be movable in a sliding motion on the circumferential side in an assembled state by an essentially flat radial outer recess on a radial inner one of the two straight edge connectors and also an essentially flat radial inner recess on the radial one of the two straight edge connectors.

4. The support element according to claim 3, wherein a total of the straight edge connectors effective as one common connector and the support connectors of the filter frame is an odd number if a number of relevant inlet openings in the cylindrical side wall of the piston is an even number.

5. The support element according to one of claim 2, wherein the ring-shaped edge connectors of the filter frame are provided with essentially identical radial outer recesses that are arranged diagonally opposite a circumferential partition gap of the ring filter.

6. The support element according to claim 2, further comprising multiple projections extending outward in a radial direction are arranged on an axially inner one of the ring-shaped edge connectors or on an axially outer one of the ring-shaped edge connectors of the filter frame distributed around a circumference, said projections contact an axially outer edge of an inner ring-shaped recess in the cylindrical side wall of the housing when the piston is moved outward in an axial direction.

7. The support element according to claim 6, wherein the projections that extend in the radial direction are constructed as circular segment-shaped bulges of the axially inner or axially outer one of the ring-shaped edge connectors arranged between the straight edge connectors and the support connectors of the filter frame.

8. The support element according to claim 6, wherein the radial projections are constructed as connector tabs formed integrally on the axially inner or axially outer one of the ring-shaped edge connectors axially adjacent to the outer straight edge connector or one of the support connectors of the filter frame.

9. The support element according to claim 2, wherein the filter screen and the filter frame of the ring filter are produced integrally as an injection molded part made from a plastic.

10. The support element according to claim 2, wherein the filter screen of the ring filter is made from a wire or fiber mesh, and the filter screen is injection molded with a plastic for forming the filter frame in an injection molding process.

11. A hydraulic support element for a variable valve train of an internal combustion engine, the hydraulic support element comprising: a cylindrical pot-shaped housing having a cylindrical side wall and a base wall; a hollow cylindrical piston guided for axial movement in said housing, the hollow cylindrical piston having a cylindrical side wall, an inner end and an outer end, the outer end extends past an outer edge of the housing and is constructed as a hemispherical bearing head; an interior of the hollow cylindrical piston includes an inner supply pressure space and an outer switching pressure space that are connectable via respective inlet openings in the cylindrical side wall of the housing and the cylindrical side wall of the piston respectively with a supply pressure line and a cylinder head side switching pressure line, the piston has, in the cylindrical side wall in an area of the inlet openings leading into at least one of the supply pressure space or the switching pressure space, a ring-shaped recess radially on an outside thereof; a compression spring biases the hollow cylindrical piston away from the base wall of the housing; and, a filter element constructed as a ring filter that is open on a circumferential side is inserted axially with a positive fit connection into the ring-shaped recess of the piston.

12. The support element according to claim 11, wherein the ring filter comprises: a cylindrical filter screen that is open on a circumferential side; and, a filter frame surrounding the filter screen, the filter frame has at least one ring-shaped edge connector that is open on the circumferential side and are arranged on axial outer edges of the filter screen.

13. The support element according to claim 12, wherein the ring filter further comprises: at least one straight edge connector arranged on circumferential-side ends of the filter screen.

14. The support element according to claim 13, wherein the ring filter further comprises: at least one support connector arranged within the filter screen on the circumferential side.

15. The support element according to claim 14, wherein a total of the straight edge connectors effective as one common connector and the support connectors of the filter frame is an odd number if a number of relevant inlet openings in the cylindrical side wall of the piston is an even number.

16. The support element according to claim 14, further comprising multiple projections extending outward in a radial direction arranged on the at least one ring-shaped edge connector of the filter frame distributed around a circumference, said projections contact an axially outer edge of an inner ring-shaped recess in the cylindrical side wall of the housing when the piston is moved outward in an axial direction.

17. The support element according to claim 16, wherein the projections are constructed as circular segment-shaped bulges of the at least one ring-shaped edge connector arranged between the straight edge connectors and the support connectors of the filter frame.

18. The support element according to claim 16, wherein the radial projections are constructed as connector tabs formed integrally on the at least one ring-shaped edge connector.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Drawings with two embodiments are provided for further illustrating the invention. Shown in the drawings are:

(2) FIG. 1 a section of a hydraulic support element according to a first embodiment of a filter element in a longitudinal center section,

(3) FIG. 1A a section of the piston of the support element according to FIG. 1 according to the first embodiment of the filter element in a perspective view,

(4) FIG. 1B the filter element according to FIGS. 1 and 1a in a first perspective view,

(5) FIG. 1C the filter element according to FIGS. 1 and 1a in a second perspective view,

(6) FIG. 2 a section of a hydraulic support element according to a second embodiment of a filter element in a longitudinal center section,

(7) FIG. 2A a section of a piston of the support element according to FIG. 2 according to the second embodiment of the filter element in a perspective view,

(8) FIG. 2B the filter element according to FIGS. 2 and 2a in a first perspective view, and

(9) FIG. 2C the filter element according to FIGS. 2 and 2a in a second perspective view.

DETAILED DESCRIPTION

(10) Below, the construction and arrangement of a filter element 30, 30 according to the invention is explained using a dual-flow hydraulic support element 2 for a variable valve train of an internal combustion engine in two embodiments. Because the structure and the function of a dual-flow hydraulic support element is known, for example, from DE 103 30 510 A1, the figures and their description are limited to the construction and arrangement of the respective filter element 30, 30.

(11) In FIG. 1, an axial section of a dual-flow hydraulic support element 2 is shown as a longitudinal center section, with this element having a cylindrical pot-shaped housing 4 and a hollow cylindrical piston 16 guided so that it can move axially within this housing. In the cylindrical side wall 6 of the housing 4, an outer ring-shaped recess 8 is formed on the outside in the radial direction, in which two diagonally opposite inlet openings 10 are arranged. In the cylindrical side wall 18 of the piston 16 there is likewise an outer ring-shaped recess 20 on the outside in the radial direction, in which two diagonally opposite inlet openings 22 are arranged. The ring-shaped recesses 8, 20 and the inlet openings 10, 22 in the cylindrical side walls 6, 18 of the housing 4 and the piston 16 are used in the installed state of the support element 2 in a supporting hole of a cylinder head for supplying engine oil from a cylinder head side switching pressure line into a switching pressure space 26 arranged in the interior of the piston 16 on the outside in the axial direction. The switching pressure space 26 is separated by a cylindrical pot-shaped partition element 28 from a supply pressure space 24 arranged in the interior of the piston 16 on the inside in the axial direction.

(12) In the outer ring-shaped recess 20 of the piston 16, a filter element 30 constructed as an open ring filter on the circumferential side is inserted with an axial positive-fit connection. The particles introduced via the cylinder head side switching pressure line with the supplied engine oil are thus held back at the ring filter 30 before entry into the switching pressure space 26, whereby the switching function in the associated rocker arm is guaranteed. Due to the circumferential side open construction of the filter element 30, its assembly on the piston 16 is possible by an elastic widening of the ring filter 30 in a simple way and without the risk of damage to the ring filter 30.

(13) In the perspective view of FIG. 1A, which shows a section of the piston 16 with the assembled ring filter 30, as well as in the perspective views of the ring filter 30 in FIGS. 1B and 1C, the structure of the ring filter 30 can be seen in more detail. Accordingly, the ring filter 30 has a cylindrical filter screen 34 that is open on the circumferential side and a filter frame 36 surrounding the filter screen 34. The filter frame 36 comprises two ring-shaped edge connectors 38, 40 that are arranged on the axial outer edges of the filter screen 34 and are open on the circumferential side, two straight edge connectors 42, 46 that are arranged on the circumferential side ends of the filter screen 34 between the ring-shaped edge connectors 38, 40, and multiple support connectors 50 arranged between the ring-shaped edge connectors 38, 40 distributed on the circumferential side within the filter screen 34.

(14) The radial inner straight edge connector 42 is provided with an essentially flat radial outer recess 44 and the radial outer straight edge connector 46 with an essentially flat radial inner recess 48, so that the straight edge connectors 42, 46 of the filter frame 36 lie one above the other so that they can move in a sliding motion on the circumferential side in the installed state. With the straight edge connectors 42, 46 acting as a common connector and counted as a single connector, as well as the two support connectors 50 of the filter frame 36, the total number of axial connectors is three, whereby it is prevented that after the assembly of the ring filter 30 on the piston 16, an edge connector 42, 46 or support connector 50 is located randomly in front of each of the two inlet opening 22 of the piston 16, whereby the supply of engine oil from the cylinder head side switching pressure line into the switching pressure space 26 would be strongly negatively affected.

(15) The ring-shaped edge connectors 38, 40 of the filter frame 36 are each provided with an essentially identical radial outer recess 52, 54 that are arranged diagonally opposite the circumferential-side partition gap 32 of the ring filter 30. Due to the two recesses 52, 54, the bending stiffness of the ring-shaped edge connectors 38, 40 of the filter frame 36 is significantly reduced there, so that this area of the filter frame 36 functions as a bending hinge, about which the halves of the ring filter 30 are folded during widening movements due to installation.

(16) On the axial inner ring-shaped edge connector 38 of the filter frame 36 there are projections 56 that extend outward in the radial direction and are distributed on the circumferential side and contact an axial outer edge 14 of a radial inner ring-shaped recess 12 in the cylindrical side wall 6 of the housing 4 for an axial displacement of the piston 8 outward in the axial direction. Due to these projections 56 on the filter frame 36 of the ring filter 30, in the not installed state of the support element 2, the piston 16 is prevented from falling out of the housing 4 and thus a polygonal ring made from wire that is typically used as transport protection can be eliminated.

(17) In the first embodiment of the ring filter 30 shown in FIGS. 1 and 1A to 1C, the radial projections 56 are constructed as circular segment-shaped bulges of the inner ring-shaped edge connector 38, which are arranged between the straight edge connectors 42, 64 and the support connectors 50 of the filter frame 36. Due to the arrangement of the bulges 56, the radial outer recess 52 is located in the axial inner ring-shaped edge connector 38 essentially centrally within the relevant bulge 56. In FIG. 1, the support element 2 is shown in the unloaded state, in which the piston 16 is located due to the contact of the bulges 56 of the filter frame 36 on the axial outer edge 14 of the inner ring-shaped recess 12 of the housing 4 in the corresponding stop position.

(18) In FIGS. 2 and 2A to 2C, the same hydraulic support element 2 is shown with a second embodiment of the ring filter 30, in which the radial projections are constructed a connector tabs 58 formed integrally on the inner ring-shaped edge connector 38. For reasons of stability, the connector tabs 58 are each arranged axially adjacent to the outer straight edge connector 46 or one of the support connectors 50 of the filter frame 36 on the inner ring-shaped edge connector 38. Due to the arrangement of the connector tabs 58, the radial outer recess 52 is located in the axial inner ring-shaped edge connector 38 essentially centrally between two connector tabs 58. In FIG. 2, the support element 2 is also shown in the unloaded state, in which the piston 16 is located by the contact of the connector tabs 58 of the filter frame 36 on the axially outer edge 14 of the inner ring-shaped recess 12 of the housing 4 in the corresponding stop position.

(19) The filter screen 34 and the filter frame 36, 36 of the ring filter 30, 30 can be produced integrally from a suitable plastic as an injection molded part. However, it is also possible that the filter screen 34 of the ring filter 30, 30 is made from a wire or fiber mesh, and that a suitable plastic is molded around the filter screen 34 for forming the filter frame 36, 36 in an injection molding process.

LIST OF REFERENCE SYMBOLS

(20) 2 Hydraulic support element 4 Housing 6 Side wall 8 Outer ring-shaped recess 10 Inlet opening 12 Inner ring-shaped recess 14 Outer edge 16 Piston 18 Side wall 20 Outer ring-shaped recess 22 Inlet opening 24 Supply pressure space 26 Switching pressure space 28 Partition element 30, 30 Filter element, ring filter 32 Separating gap 34 Filter screen 36, 36 Filter frame 38, 38 Inner ring-shaped edge connector 40 Outer ring-shaped edge connector 42 Inner straight edge connector 44 Outer recess 46 Outer straight edge connector 48 Inner recess 50 Support connector 52, 52 Recess 54 Recess 56 Radial projection; bulge 58 Radial projection; connector tab