CONNECTING ROD FOR INTERNAL COMBUSTION ENGINE WITH ECCENTRICAL ELEMENT ADJUSTMENT ARRANGEMENT FOR ADJUSTING AN EFFECTIVE CONNECTING ROD LENGTH

Abstract

A connecting rod for an internal combustion engine with an eccentrical element adjustment arrangement for adjusting an effective connecting rod length, the eccentrical element adjustment arrangement including at least one ball joint including a ball head that is arranged at a support rod and supported in a ball head receiver of a piston, wherein the ball head is secured at its outer surface in the ball head receiver by safety devices against sliding out of the ball head receiver, and wherein the safety devices are configured as a one-piece or a multi-piece annular safety element which is arranged in the piston at least partially bonded or form locking.

Claims

1. A connecting rod for an internal combustion engine with an eccentrical element adjustment arrangement for adjusting an effective connecting rod length, the eccentrical element adjustment arrangement comprising: at least one bail joint including a ball head that is arranged at a support rod and supported in a ball head receiver of a piston, wherein the ball head is secured at its outer surface in the ball head receiver by safety devices against sliding out of the bail head receiver, and wherein the safety devices are configured as a one-piece or a multi-piece annular safety element which is arranged in the piston at least partially bonded or form locking.

2. The connecting rod according to claim 1, wherein the safety element is configured in two components and includes a safety ring and an attachment ring.

3. The connecting rod according to claim 2, wherein the attache gent ring is pressed or welded into the piston.

4. The connecting rod according to claim 2, wherein the safety ring is configured axially slotted.

5. The connecting rod according to claim 2, wherein the safety ring includes a radially inward cambered contact surface for the ball head.

6. The connecting rod according to claim 1, wherein the safety element is configured as a one piece safety ring.

7. A connecting rod according to claim 6, wherein the safety ring is pressed or welded into the piston.

8. The connecting rod according to claim 6, wherein the safety ring includes an annular radially inward cambered contact surface for the ball head.

9. The connecting rod according to claim 1, wherein the support rod is configured as an assembled support rod made from at least two components, wherein the support rod includes a rod element with a joint element and with a piston connector, wherein the joint element and the piston connector are arranged at opposite ends of the rod element, wherein the rod element is connected with the joint element or with the piston connector by a welding method and the piston connector is configured as a ball head,

10. The connecting rod according to claim 9, wherein the joint element is configured as a ball.

11. The connecting rod according to claim 9, wherein the joint element is configured as a sleeve whose longitudinal axis is configured perpendicular to a longitudinal axis of the rod element, in particular wherein the joint element includes an impressed bearing bushing.

12. The connecting rod according to claim 9, wherein the rod element is configured as a tube.

13. The connecting rod according to claim 9, wherein a cross section of the rod element is configured polygonal.

14. A connecting rod according to claim 9, wherein the rod element is configured integrally in one piece together with the joint element.

15. A variable compression internal combustion engine comprising: at least one connecting rod according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Further advantages can be derived from the subsequent drawing description. The drawing illustrate an embodiment of the invention. The drawings, the description and the claims include several features in combination. A person skilled in the art will advantageously view the features also individually and will combine them into additional useful combinations, wherein:

[0035] FIG. 1 illustrates a connecting rod with two ball joints in a longitudinal sectional view;

[0036] FIG. 2 illustrates a support rod with a piston according to a first embodiment of a connecting rod according to the invention in a side view;

[0037] FIG. 3 illustrates the support rod according to FIG. 2 in a longitudinal sectional view of the sectional plane A-A;

[0038] FIG. 4 illustrates a support rod with a piston according to another embodiment of a connecting rod according to the invention in a top view;

[0039] FIG. 5 illustrates the support rod according to FIG. 4 in a longitudinal sectional view of the sectional plane A-A;

[0040] FIG. 6 illustrates the support rod according to FIG. 4 in a longitudinal sectional view in the sectional plane B-B;

[0041] FIG. 7 illustrates a support rod with two balls according to another embodiment in an isometric view; and

[0042] FIG. 8 illustrates the support rod according to FIG. 7 in a longitudinal sectional view,

DETAILED DESCRIPTION OF THE INVENTION

[0043] In the drawing figures identical or like components are designated with identical reference numerals. The drawing figures merely illustrate exemplary embodiments and do not limit the spirit and scope of the invention.

[0044] FIG. 1 illustrates a schematic view of an exemplary connecting rod 1 for a variable compression internal combustion engine with an eccentrical element 2 for adjusting an effective connecting rod length which is defined as a distance of a center axis of a crank bearing eye 12 from the center axis of the bore hole of an eccentrical element 4. The eccentrical element adjustment arrangement 2 includes an eccentrical element 4 that cooperates with a one-piece or multi-piece eccentrical element lever 3 in which a non-illustrated wrist pin of a cylinder piston is receivable. An adjustment travel of the eccentrical element adjustment arrangement 2 is adjustable by a mechanical or hydraulic switch valve 5.

[0045] A rotation of the adjustable eccentrical element adjustment arrangement 2 is initiated by an impact of high mass forces (at low compression .sub.low) and gas load forces (at high compression .sub.high) of the internal combustion engine that impact the eccentrical element adjustment arrangement 2 during an operating stroke of the internal combustion engine. During the operating stroke (operating cycle) effective directions of torques that impact the eccentrical element adjustment arrangement 2 change continuously. The rotating movement or adjustment movement is supported by one or plural pistons 6, 7 that are loaded with hydraulic fluid, in particular with motor oil, and that are integrated in the connecting rod 1 or the pistons 6,7 prevent a resetting of the eccentrical element adjustment arrangement 2 due to varying force effective directions of forces impacting the eccentrical element adjustment arrangement 2.

[0046] The pistons 6, 7 are respectively moveably supported in a cylinder bore hole 8, 9 of a hydraulic cylinder 14, 15 of the connecting rod 1 and connected with support rods 10, 11 which are in turn pivotably connected with the eccentrical element lever 3. In an exemplary manner the support rods 10, 11 of the eccentrical element adjustment arrangement 2 are connected by cylindrical rollers 46, 47 with the eccentrical element lever 3.

[0047] The connecting rod 1 includes the crank bearing eye 12 for connecting the connecting rod 1 with a crank shaft of an internal combustion engine and a wrist pin bearing eye 13 for connecting the connecting rod 1 with the cylinder piston of the internal combustion engine.

[0048] The pistons 6, 7 are moveably arranged in cylinders 14, 15 formed by the cylinder bore holes 8, 9, configured as hydraulic chambers and loaded through inlets 16, 17 from the crank bearing eye 12 with hydraulic fluid, e.g., motor oil, through the check valves 18, 19. Thus, the check valves prevent a backflow of the hydraulic fluid from the hydraulic chambers 14, 15 back into the inlets 16, 17, but they facilitate a pulling of hydraulic fluid into the hydraulic chambers 14, 15.

[0049] The hydraulic chambers 14, 15 are furthermore connected through non-illustrated drains with the switch valve 5 which can be configured as a hydraulic valve or as a mechanical valve and which is connected with the crank bearing eye 12 through a drain conduit 22.

[0050] It is evident that the connecting rod 1 includes a connecting rod body and a connecting rod cover attached thereto.

[0051] A groove 23 is provided on a circumference of the crank bearing eye 12 in the portion of the connecting rod body 20 wherein inlets 16, 17 and the drain conduit 22 lead into the groove. Since the groove 2 is only arranged on a portion of the crank bearing eye 12 the load bearing capability of the bearing in the crank bearing eye is only impaired by a minimum amount.

[0052] The configuration of the described connecting rod 1 is only represented in an exemplary manner and the eccentrical element lever connection according to the invention can also be used in other variants of the connecting rod with an eccentrical element adjustment arrangement. Thus is possible for example to arrange the switch valve 5 in the portion of the connecting rod cover 21. Furthermore the described check valves 18, 10 can be provided integrated in the switch valve 5. Also the hydraulic supply of the hydraulic chambers 14, 15 can deviate from the described embodiment.

[0053] FIGS. 2-6 include support rods 10 in two embodiments of the connecting rod 1 according to the invention. As a matter of principle the supports rods 10, 11 and the pistons 6, 7 are configured identical and merely differ in diameter. Therefore the support rod 10 is respectively illustrated and described in an exemplary manner.

[0054] FIGS. 2 and 3 illustrate the support rod 10 according to a first embodiment. FIGS. 4-6 illustrate a second embodiment. The support rod 10 respectively includes a ball joint 24 and a ball head 26 that is arranged at the support rod 10, wherein the ball head is supported in a ball head receiver 25 of the piston 6. The ball head 26 is secured at its outer surface in the ball head receiver 25 by safety devices against sliding out of the ball head receiver 25.

[0055] The ball head receiver 25 includes a cambered base element that is adapted to the outer contour of the ball head 26 and on which the ball head 26 can slide to facilitate tilting the support rod 10.

[0056] A one piece or multi piece safety element is configured as a safety device according to the invention wherein the safety element is at least partially bonded or arranged in a form locking manner in the piston 6, 7.

[0057] The first embodiment is evident from FIG. 3 wherein the safety element is configured in two components and includes a safety ring 27 and an attachment ring 28.

[0058] The safety ring 27 can be configured for example from metal or from a synthetic material. The configuration can be configured in one piece, flexible or in two pieces.

[0059] The safety ring 27 can additionally include a contour shaped as an annular radially inward cambered contact surface 33 for the ball head 26, wherein the contour provides a contact area for the support rod 10 in order to reduce the Hertz surface pressure.

[0060] The safety ring 27 can be configured axially slotted in an alternative embodiment in order to be able to run the safety ring over the support rod 10 by slight expansion during assembly.

[0061] The attachment ring 28 is configured from metal and provided pressed or welded into the piston 6 in order to individually adjust the axial clearance of the support rod 10. The attachment ring 28 can be slotted or it has an inner diameter in a particularly advantageous embodiment wherein the inner diameter is greater than the ball diameter of the support rod 10 so that the attachment ring can be configured unslotted. The attachment ring can be welded e.g., at the free edge 35 of the piston 6,

[0062] According to a second embodiment that is illustrated in FlGS. 4-6 the safety element is configured as a one piece safety ring 29 as illustrated in FIGS. 4-6.

[0063] Furthermore the support rod 10 is not provided in one piece in FIG. 5 but configured as an assembled support rod and includes the components joint element 30, rod element 31 and piston connector element 32, wherein the piston connector element 32 is configured as a ball head 26. The components joint element 30, rod element 31 and piston connector 32 are connected with each other by a welding method.

[0064] Generally the support rod 10 can be configured as an assembled support rod with at least two components and the components joint element 30, rod element 31 and piston connector 32 or the components rod element 31 with integrated joint element 30 and piston connector 32 or the components rod element 31 with integrated piston connector 32 and joint element 30, wherein at least two of the components are connected with each other by a welding method. Advantageously the piston connector 32 is configured as a ball head 26 in order to facilitate easy tilting of the support rod 10 relative to the piston 6.

[0065] The joint element 30 is configured as a sleeve whose longitudinal axis is configured orthogonal to the longitudinal axis of the rod element 31. In particular the joint element 30 includes a pressed in bearing bushing. Alternatively, however, it is also possible that the joint element is configured as a ball.

[0066] The rod element 31 can be advantageously configured as a tube which has rather high bending stiffness for a rather low weight. Alternative also a rod element with a polygonal cross section or with another profile for a surface moment of inertia that is optimized for bending stiffness can be used. Furthermore the rod element 31 with the joint element 30 can be integrally configured in one piece in an advantageous embodiment.

[0067] Before welding the ball 32 down advantageously the safety ring 29 is pushed over the support rod 10. Thus, the unslotted safety ring 29 that is pressed into the piston 6 or welded to the piston 6 can be configured in a simple and more cost effective manner with reduced tolerances. The safety ring 29 can be welded e.g. to the free edge 35 of the piston 6.

[0068] Alternatively it is also possible that the safety ring 29 is provided slotted but flexible. Then the safety ring 29 can also be slid over an assembled support rod 10 and can apply from an inside against the ball head receiver 25 of the piston 6 when the safety ring 29 is sized accordingly and can be fixated at this location e.g. by welding.

[0069] Also the safety ring 29 advantageously has a contour with an annular radially inward cambered contact surface 34 for the ball head 26, wherein the contact surface provides a contact area with the support rod 10 in order to reduce the Hertz surface pressure,

[0070] As another embodiment illustrated in FIGS. 7 and 8 the support rod 10 includes a ball for a link element 30 as well as for a piston connector 32 which is connected with the respective ends of a rod element 31. This variant can be produced particularly well in combination with a one piece eccentrical element lever 3 that has been produced by a metal injection molding (MIM) method or by a fine casting method. Advantageously standard elements like hardened balls can be used for the joint element 24 and for the piston connector 26 and rods or tubes can be used for the rod element 25.