MXPA00002519A - Connecting rod for a hermetic refrigerating compressor - Google Patents

Abstract

The invention concerns a connecting rod for a hermetic refrigerating compressor, in which the connecting rod forms the mechanical connection between a crank and a piston. The purpose of the invention is to reduce wear in the crank bearing of the compressor with simple means. This is obtained by reducing compressive stresses in the connecting rod by making a cut-out in the connecting rod near the crank bearing. The cut-out causes deflection of compressive stresses, so that they are distributed over a larger share of the crank bearing surface. Also the outer shape of the connecting rod is adapted, so that also here the compressive stresses are distributed over a larger bearing surface. This reduces the wear on the crank bearing of the compressor and increases the life.

Description

Connecting rod for an airtight relieving compressor DESCRIPTION OF THE INVENTION The invention concerns a connecting rod for a hermetic refrigeration compressor, in which an axis is connected to a piston by means of a crankshaft and a connecting rod, the piston makes a forward and backward movement, the connecting rod is connected to the crankshaft by means of a first support and to the piston by means of a link, the connecting rod consists of means to prevent the direct transfer of the compressive tension between the common movement center of the crankshaft and the connecting rod and the common movement center of the connecting rod and the piston. The North American Patent no. No. 2,846,897 concerns a connecting rod for a combustion engine, in which the crankshaft support comprises two halves assembled with screws. The connecting rod consists of two flanges that extend longitudinally assembled with a central flange. In its transition to the crankshaft support the central flange has an arched opening limited on both sides by the flanges extending longitudinally. DE 32 38 489 A1 also concerns a connecting rod for a combustion engine with a crankshaft support comprising a roller support, the REF .: 32792 problem to be solved is to ensure the distribution of the compressive tension on several rollers. This problem is solved in that the connection between the supports of the rod is formed by two tabs, which are mutually connected by a bridge, the openings made between the tabs and the bridge. Thus, it is obtained that the compressive stresses are not transferred directly between the centers of movement of the connecting rod, and that the stresses are distributed among several rollers. It is also described that the support ring is elastic. However, an elastic support ring will produce pressures, when it is not supported by the flanges. Thus, the forces will be concentrated in the eyelashes, and the compressive tensions between the eyelashes will be substantially reduced. The problem is solved in that with the two tabs the tensions can, in the worst case, run through two rollers. In both aforementioned documents, the compressive stresses run in the tabs, which are tangentially connected with the supports. Thus, there will scarcely be any direct transfer of compressive stresses between the centers of motion, and the load on the supports on the direct connection line is very small. This provides an increased load of the supports in other parts of the support circumference, where the increase in use can cause a reduction in life. Figure 1 shows a simulated computer calculation of compressive stresses on a crankshaft support, which is connected to the piston rod support by means of tangentially arranged flanges. It is the purpose of the invention to increase the life of the connecting rod for a hermetic refrigeration compressor using only simple means. This task can be solved with a connecting rod as described in the introduction, where the connecting rod is provided with a cut, the cut is placed at a distance to the supporting surface of the first support, the distance becomes from 15 ° 0 to 30% of the diameter of the first support, the ratio between the area of the first opening of the support and the area of the cut is 0.1% at D o * This provides an equal distribution of compressive stress over a larger portion of the support surface, which results in reduced wear of the crankshaft support of the connecting rod. Only an adaptation of the place and size of the cut will provide an optimal solution. If it is overcompensated, a fall - it may occur in the line of direct connection between the centers of movement "of the connecting rod, and at the same time two new concentrations of tension can occur that provide problems of use. Advantageously, the invention can be made so that The largest cross-sectional measure of the cut is 5% to 15% of the inside diameter of the first support of the connecting rod, this will provide a release of the compressive stresses without causing the formation of new maximum pressure points with a distance to the plane of symmetry. Advantageously, the outer contour of the rod around the cut is formed by a first concave line, which extends in a second convex line. Thus, compressive stresses can run along the outside of the connecting rod without deviating from the sharp edges. Advantageously, the material surrounding the cut, facing the outer contour, is thicker than the larger transverse measure of the cut. Thus, compressive stresses can be distributed over a greater angle. Advantageously, the cut is arranged at a distance from the circumference of the first support, where the distance is larger than the larger transverse measurement. Thus, compressive stresses are allowed to act directly under the inner hole. Advantageously, the convex line of the outer contour forms an angle a with the outer ring of the first support. Thus, the conditions of production are considered, if the connecting rod has to be made as a sintered workpiece. The angle may also necessarily be exterior with respect to the location in a hermetic compressor. Advantageously, the cut is arranged in the rod in a position displaced to one of the sides in relation to the line of direct connection between the centers of the supports. Thus, a reduction of the maximum point of the compressive stresses can be obtained. A friction in the bearings of the connecting rod can cause a displacement of the compressive stresses from the line of symmetry of the connecting rod in the direction of the edge of the connecting rod. To ensure a reduction of compressive stresses, the optimal arrangement and the shape of the cut can be calculated to move in relation to the line of symmetry. The outer shape of the connecting rod can also be optimized in such a way that the sides of the connecting rod deviate from each other. In the following, the invention is explained based on the following drawings: Figure 1 shows a curve calculated in a computer of the compressive tension of the state of the art. Figure 2 a top view of the connecting rod. Figure 3 a cross section of the connecting rod. 4 shows a section of a connecting rod for a hermetic compressor of the state of the art. Figure 5 a section of a connecting rod with a changed outer contour. Figure 6 a section of a connecting rod with a changed outer contour and a cut that is transverse. Figure 7 radial load curves for Figures 4, 5 and 6. Figure 8 a top view of a connecting rod, the cut is shown as an ellipse displaced from the line of symmetry of the connecting rod. Figure 9 shows a cross section of the connecting rod of Figure 8. Figure 1 shows a computer simulated graph of the radial stresses, recorded through a connecting rod as described in DE 32 38 489 Al. Since the connecting rod is symmetrical, the Calculation of the computer is done with an increasing angle of the plane of symmetry of the connecting rod. Thus, the curve only shows compressive stresses on one side of the common connection line of the rotating points. Figure 1 clearly shows that the maximum compressive stresses are displaced at 40 ° in relation to the plane of symmetry of the connecting rod. Figure 1 shows a clear overcompensation, when the radial tension has been reduced to approximately 10% in areas around the plane of symmetry, considering that the curve has a maximum of 40 °, and as here the curve is symmetric around 0 °, it seems that two new maximum points of radial tension occur. Figure 2 shows a connecting rod 1 for a hermetic refrigeration compressor. The connecting rod has a first support 2, forming a support together with the crankshaft, the connecting rod and the crankshaft has a common movement center 4. The connecting rod also has a second support 3 that forms the link for a piston (not shown), a common motion center 5 exists between the link and the connecting rod. The connecting rod is shown with a cut that is transverse 6, shown therein as a circular hole. The outer contours comprise a first concave line 7 extending in a convex line 8 also shown. Furthermore, it is shown that the cut that is transverse 6 is placed in the symmetry line 9 of the connecting rod. In the transition in the support 2, the convex line 8 forms an angle a.

Figure 3 shows a cross section of Figure 2 along the plane of symmetry 9. It appears that from Figure 3 the cut 6 is formed by a circular hole that is transverse. Figure 4 shows a section of a connecting rod for a hermetic refrigeration compressor according to the state of the art. Figure 5 shows a section similar to that in Figure 4, the outer contours of the connecting rod have been corrected by the first concave line 7, which extends in a convex line 9, ending at an angle a against the outer surface of the support. Figure 6 also shows a section of a connecting rod with the same outer contours as in Figure 5, with a cut that is transverse 6 therein. Figure 7 shows the curves 10, 11 and 12, which have been computed in the computer in the same way as the curve in Figure 1. Curve 10 corresponds to a connecting rod as shown in Figure 4, considering that the curve 11 corresponds to a connecting rod as shown in Figure 5, and curve 12 corresponds to the connecting rod shown in Figure 6. The practical use of a connecting rod as shown in Figures 4 and 7, curve 10, will cause the wear on the surface of the crankshaft support 2 (Figure 2), where the line of direct connection between the two centers of movement crosses the support surface. In Figure 7, the maximum radial tension is expressed to have the value 1. In curve 11, which corresponds to Figure 5, this value has been reduced to approximately 0.93, and curve 12 shows a further reduction, ie to 0.64 when the connecting rod is used as shown in Figure 6. The height of curve 12 has been reduced, and at the same time it has moved outwards, so that the radial charges in the support are distributed in a relatively larger portion of the supporting circumference. Thus, compressive stresses are distributed over a larger portion of the supporting circumference, and wear of the support in the connecting line between the common movement centers of the connecting rod is prevented. Figures 8 and 9 show an alternative embodiment with a cut 13 shown as an ellipse displaced from the line of symmetry of the connecting rod. The frictional forces of the connecting rod supports can act on the longitudinal compressive tensions of the connecting rod in a way that they extend in a displaced position from the connection line of the movement centers. Thus, an asymmetric arrangement of the cut may be desirable. An alternative embodiment with the same effect can be obtained with a cut that is not transverse, and particularly, if the rod is produced by sintering means, it can be done with a cut without being transverse. In addition, the desired effect can be obtained with cuts from both sides with a wall between the cuts. The invention can also be made with several cuts from both sides.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects or products to which it refers.

Claims (8)

1. Having described the invention as above, the content of the following claims is claimed as property: 1. A connecting rod for a hermetic refrigeration compressor, wherein an axle is connected to a reciprocating piston by means of a crankshaft and a connecting rod, the connecting rod it comprises a first support for the connection to the crankshaft, a link for the connection to the piston, and an intermediate portion connecting the first support and the link, the connecting rod has means to prevent the direct transfer of the compressive tension between the common movement center of the crankshaft and the connecting rod and the common movement center of the connecting rod and the piston, the connecting rod also has a cut in the intermediate portion, characterized in that the intermediate portion has a solid structure with a substantially uniform thickness, the cut is placed at a distance to the supporting surface of the first support, the distance becomes 15% to 30% of the diameter of the first support , and the relationship between the area of the cut and the area of the first opening of the support is 0.1% at
2. * J or • 2. The connecting rod according to claim 1, characterized in that the largest transverse measure of the cut is 5% to 15% of the internal diameter of the first support of the rod.
3. 3. The connecting rod according to one of claims 1 or 2, characterized in that the outer contour of the rod around the cut is formed by a first concave line, which extends in a second concave line.
4. 4. The connecting rod according to one of claims 1 to 3, characterized in that the material surrounding the cut that faces the outer contour is of greater thickness than the larger transversal measurement of the cut.
5. 5. The connecting rod according to one of claims 1 to 4, characterized in that the cut is placed at a distance from the circumference of the first support, where the distance is greater than the transverse measurement greater than the cut.
6. 6. The connecting rod according to claim 3, characterized in that the convex line of the outer contour forms an angle a with the outer ring of the first support.
7. 7. The connecting rod according to claim 6, characterized in that the angle a is between 90 and 180 degrees.
8. 8. The connecting rod according to one of claims 1 to 7, characterized in that the cut is placed in the rod in a position displaced to one of the sides in relation to the line of direct connection between the centers of the supports. Connecting rod for a hermetic refrigeration compressor SUMMARY OF THE INVENTION The invention concerns a connecting rod for a hermetic refrigeration compressor, wherein the connecting rod forms the mechanical connection between a crankshaft and a piston. The purpose of the invention is to reduce wear on the compressor crankshaft support with simple means. This is obtained by reducing the compressive stresses in the connecting rod by making a cut in the connecting rod near the crankshaft support. The cut causes the deviation of the compressive stresses, so that they are distributed over a larger portion of the crankshaft support surface. The outer shape of the connecting rod is also adapted, so that here also the compressive stresses are distributed on a crankshaft support surface. This reduces wear on the compressor crankshaft holder and increases its life.