GB1577352A

GB1577352A - Gudgeon pin

Info

Publication number: GB1577352A
Application number: GB1443877A
Authority: GB
Original assignee: Karl Schmidt GmbH
Current assignee: Karl Schmidt GmbH
Priority date: 1976-04-08
Filing date: 1977-04-05
Publication date: 1980-10-22
Also published as: JPS6027865B2; DE2615212B2; JPS52124564A; BR7702209A; DE2615212A1; FR2347586A1

Description

(54) GUDGEON PIN (71) We, KARL SCHMIDT GmbH, a body corporate organised under the laws of the German Federal Republic, of Christian Schmidt-Strasse 8/12, 7107 Neckarsulm, German Federal Republic, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a gudgeon pin for a piston, particularly for a piston for an internal combustion engine.

A gudgeon pin is a force-transmitting member, which connects a piston to a connecting rod. The forces acting on the piston deflect the latter and result in an oval deformation thereof. The periodic deformation of the pin, consisting of deflection and flattening, stresses the bosses for the pin in horizontal and vertical planes. When the gudgeon pin is dimensioned for adequate strength, the mean bearing load for the bosses for the pins is also tolerable, as a rule.

Because the lubrication is inadequate in most cases, the average bearing load must not exceed 600 kg./cm.2 with aluminium. Nevertheless, the deflection of the pin results in an application of loads to the inner upper portion of the bosses for the pin and these loads may be a multiple of the above mentioned mean value. Very high peak pressures arise particularly as the engine is started, as a rule, and in conjunction with a small clearance between the pin and the boss may result in excessively high stresses due to the oval deformation of the pin.

Extensive investigations have shown that, particularly in diesel engines, the highest stress arises in the piston at the upper inner edge of the hole for the pin.

In order to reduce the peak stresses in that region, it is known, e.g., from W.-D. Ben singer and A. Meyer: "Kolben, Pleuel und Kurbelwelle bei schnellaufenden Verbrennungs - motren", Berlin/Göttingen/Heidel- berg, 1961, page 10, to form the inner end of the gudgeon pin bosses with a radius of 1 mm. or to make the bosses for the pin so elastic in that region that the bosses can substantially conform to the deflection of the gudgeon pin without overstressing the piston material. It has also been proposed to form the inner edge of the bosses for the pin with a taper of 1:100.

It has also been proposed to shrink rightangled reinforcing rings on the outside periphery of the gudgeon pin bosses. As a result, that portion of the bosses on which the reinforcing ring has been shrunk expands less in the operating condition than the remaining portion of the bosses. In order to compnesate for this differential expansion, the bore in the boss is narrower toward the side of the shrunkon ring so that under operating conditions the bores will become cylindrical and assume the function of non-reinforced bores.

A gudgeon pin boss which has a bore that has an oval cross-sectional shape, the minor aixs of which is parallel to the longitudinal axis of the piston has also been proposed.

This design results in a minimum clearance between the pin boss and the pin and in a lower tendency to seize and lower noise.

It has further been proposed to shape the bores in the gudgeon pin bosses to allow for the mechanical and thermal loads applied by the piston pin. Because such a design of the bores in the piston bosses involves a relatively high expenditure, the provision of the bore with an edge which is radiussed circularly is still preferred in practice even though this design deos not minimize the load on the bosses for the pin.

According to the present invention there is provided a gudgeon pin for a piston, wherein the pin is recessed throughout a region which, when the pin is in a position in a piston, extends from the inner edge of each of the gudgeon bosses of the piston to the ajacent inner edge of a connecting rod small end bearing and around the entire periphery or part of the periphery of the pin, each recess having a conical taper in cross section and a depth at a given point which is at least as large as the deflection of the pin will be at the same point when the pin is in use under the design load.

With this design it is possible to arrange for the stresses which arise under maximum load at the apex, particularly adjacent to the upper inner edge of the bosses for the pin, to be distributed as uniformly as possible throughout the length over which the pin engages the boss in the bore thereof.

In order to ensure that the gudgeon pin will not be loaded at the edges, the depth of the recess at a given point is suitably slightly larger than the deflection of the pin will be at the same point. The recess is preferably conically tapered at an angle of 8 to 14'.

As a result of these measures, the stresses in the gudgeon pin bosses and in the connecting rod are kept within a permissible range so that an application of pressure by the edges and resulting cleavages are avoided.

In order to enable the invention to be more readily understood, reference will now be made to the accompanying drawing, which illustrates diagrammatically and by way of example an embodiment thereof, and which is an axial section through a piston.

Referring now to the drawing, there is shown a piston 3 having a gudgeon pin 4 mounted in bores 1 of the gudgeon pin bosses 2. The gudgeon pin 4 has two recesses 6, each of which extends from the inner edge of each boss into the region of the adjacent inner edge of a connecting rod small end bearing 5 and has a conical taper in cross-section, and a depth at a given point which is slightly larger than the deflection of the pin 4 will be at the same point when in use under the design load.

WHAT WE CLAIM IS:- 1. A gudgeon pin for a piston, wherein the pin is recessed throughout a region which, when the pin is in position in a piston, extends from the inner edge of each of the gudgeon bosses of the piston to the adjacent inner edge of a connecting rod small end bearing and around the entire periphery or part of the periphery of the pin, each recess having a conical taper in crosssection and a depth at a given point which is as least as great as the deflection of the pin at the same point will be under the design load.

2. A gudgeon pin as claimed in claim 1, wherein each recess has an angle of taper of 8 to 14'.

3. A gudgeon pin for a piston substantially as hereinbefore described with reference to the accompanying drawing.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. point which is at least as large as the deflection of the pin will be at the same point when the pin is in use under the design load. With this design it is possible to arrange for the stresses which arise under maximum load at the apex, particularly adjacent to the upper inner edge of the bosses for the pin, to be distributed as uniformly as possible throughout the length over which the pin engages the boss in the bore thereof. In order to ensure that the gudgeon pin will not be loaded at the edges, the depth of the recess at a given point is suitably slightly larger than the deflection of the pin will be at the same point. The recess is preferably conically tapered at an angle of 8 to 14'. As a result of these measures, the stresses in the gudgeon pin bosses and in the connecting rod are kept within a permissible range so that an application of pressure by the edges and resulting cleavages are avoided. In order to enable the invention to be more readily understood, reference will now be made to the accompanying drawing, which illustrates diagrammatically and by way of example an embodiment thereof, and which is an axial section through a piston. Referring now to the drawing, there is shown a piston 3 having a gudgeon pin 4 mounted in bores 1 of the gudgeon pin bosses 2. The gudgeon pin 4 has two recesses 6, each of which extends from the inner edge of each boss into the region of the adjacent inner edge of a connecting rod small end bearing 5 and has a conical taper in cross-section, and a depth at a given point which is slightly larger than the deflection of the pin 4 will be at the same point when in use under the design load. WHAT WE CLAIM IS:-

1. A gudgeon pin for a piston, wherein the pin is recessed throughout a region which, when the pin is in position in a piston, extends from the inner edge of each of the gudgeon bosses of the piston to the adjacent inner edge of a connecting rod small end bearing and around the entire periphery or part of the periphery of the pin, each recess having a conical taper in crosssection and a depth at a given point which is as least as great as the deflection of the pin at the same point will be under the design load.