BRIEF DESCRIPTION OF THE DRAWINGS
Further features and advantages of the invention emerge from the following figure description.
In the drawing:
FIG. 1 shows an exemplary embodiment of the invention with the mounting position of the piston;
FIG. 2 shows the exemplary embodiment from FIG. 1 with the piston mounted;
FIG. 3 shows an exemplary embodiment of the piston;
FIG. 4 shows the piston from FIG. 3 in a perspective view; and
FIG. 5 shows the mounting of the piston in a sectional illustration.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In FIG. 1, an exemplary embodiment of the invention is shown in the state in which the piston is being mounted and threaded into the associated spherical shell of the drive flange. The drive shaft 1 of the variable capacity axial piston machine has a drive flange 2, on whose end face 3 the pistons 4 are pivotably mounted. For this purpose spherical shells 5 are formed in the end face 3 of the drive flange 2 and accommodate the spherical heads 6 of the displacement pistons 4. The spherical shells 5 go beyond the semisphere. They comprise an angle which is greater than 180° and open towards the pistons with a circular opening 7 which is smaller than the spherical shell diameter.
The mounting of the piston is made possible by the fact that a transverse groove 11 passing through the circular opening 7 is formed and in the example illustrated, as a circumferential groove forms a circular ring around the longitudinal axis of the drive shaft. The specially designed head 6 having the retaining collar 10 is pushed into the spherical shell obliquely in the axial direction through this transverse groove 11. The retaining collar 10 and the groove dimensions are configured in such a way that the mounting of the pistons is possible only with the illustrated highly oblique position of the piston axis in relation to the shaft axis. The angle between the end face 3 of the drive flange 2 and the piston axis can be kept particularly small by the fact that mounting grooves 12 running radially from the shaft axis to the spherical shells 5 are provided in the end face 3 of the drive flange 2, so that an extreme oblique position can be achieved which deviates considerably from the working position of the pistons, in which only smaller oblique positions occur, equivalent to a considerably larger angle between the piston axis and the end face 3.
FIG. 2 corresponds to the illustration of FIG. 1 and shows the piston 4 in the mounted position with the spherical head 6 pushed into the spherical shell 5 and an orientation of the pistons corresponding to their working position. The circumferential transverse groove 11 and the mounting grooves 12 are formed as in FIG. 1. Alternatively, the construction can also be designed such that the mounting grooves 12 run outwards, for example, the pistons 4 assuming a position during the mounting which is not oriented obliquely towards the shaft axis but outwards, obliquely away from the shaft axis.
In FIGS. 3 and 4, the piston 4 with its head 6 is illustrated detail. The piston 4 extends along the piston longitudinal axis 19. The head 6 is basically spherical with a diameter 18 in order to form a spherical joint with the spherical shells in the drive flange. The center of the sphere of the piston head 6 and its vertex 13 lie on the piston longitudinal axis 19. The sphere of the head 6 is in this case not formed as a solid body. To a certain extent, it is reduced to a spherical section 9 at the vertex 13 of the piston 4 and to the retaining collar 10. In the example illustrated the spherical section at the vertex 13 has, in the direction of the piston longitudinal axis, a height of about ⅕ to ¼ of the sphere diameter. A recess 8 is provided between spherical section 9 and retaining collar 10. This recess 8 has a diameter which is smaller than the diameter of the circular opening 7 of the spherical shell and reaches approximately as far as the central plane of the sphere. The retaining collar 10 forms a spherical layer and extends from approximately the central plane of the sphere in the direction of the adjacent piston rod 21 with a spherical layer height of about ⅙ of the sphere diameter. The recess 8 is rotationally symmetrical in relation to the piston longitudinal axis 19. In this way, a circularly cylindrical part with a smaller diameter than the sphere diameter is formed between the spherical section 9 and the retaining collar.
The piston 4 has a longitudinal bore 20 (FIG. 5) with 35 an opening at the vertex 13 of the piston head 6, through which the hydraulic pressure from the cylinder chamber is led to the hydrostatic pressure relief face of the surface of the spherical section 9. In order that the pressure can propagate on the pressure relief face a spiral groove 16 is introduced there which originates from the opening of the longitudinal bore in the vertex 13 of the spherical section 9 and ends in a circumferential groove 14 which limits the pressure area. Following the circumferential groove 14 in the form of a circular ring there is formed a sealing surface 15, likewise in the form of a circular ring.
In FIG. 5, the piston 4 and the relationships as the piston 6 is pushed into the spherical shell 5 of the drive flange are illustrated once more in section. The installation is carried out in the mounting direction 17 at the smallest possible angle α between the end face 3 of the drive flange 2 and the piston longitudinal axis 19 so that a sufficiently large difference from the maximum oblique position occurring during the operation of the axial piston machine is provided. The spherical section 9 can be introduced readily into the spherical shell 5 because of the recess 8 while the retaining collar 10 is threaded through the transverse groove described previously. The result is then an operating angle complementary to the angle α of 90° minus a minus a safety margin of at least 10° so that in the working position during the operation of the axial piston machine the piston is retained securely by the spherical shell going beyond the semisphere.
Patent Application
20070251377
