DE3512496A1 - Spherical piston for positive-displacement machines - Google Patents

Abstract

The invention relates to a spherical piston for positive-displacement machines, especially for slow-running radial-piston machines in eccentric construction. The object of the invention is to provide a positive-displacement machine for high operating pressures with low wear and a good sealing effect which, utilising the advantages of the spherical piston, increases the service life and the efficiency of the machine. This object is achieved by there being arranged, between the cylinder bore and the surface of the spherical piston facing the cylinder chamber, a moulded sealing ring which is guided in the cylinder bore and whose geometric shape matches the shape of the space forming between the cylinder bore and the surface of the sphere, and by the moulded sealing ring being pressed onto the surface of the sphere via a resilient retaining device.

Description

Kufflel piston for displacement machines

The invention relates to a ball piston for positive displacement machines, especially for hydrostatic, slow-running radial piston machines in eccentric design.

The design of the working piston as a spherical piston for hydrostatic Displacement machines is known. The advantages of the spherical piston are: that the radial dimensions of the displacement machines are kept relatively small and jamming of the ball piston in the cylinder bore is excluded is.

Due to the necessary clearance between the ball piston and However, the cylinder bore and the line contact between the two components are the Beck losses relatively high.

The wear caused by the line contact leads to further wear Leakage losses. For these reasons, the hydraulic machines are generally with Ball piston designed for low working pressures. Is the ball piston as a loose ball realized, the wear can be kept within limits, since side forces are not are present and the ball can rotate as desired.

With E-hydraulic machines for higher working pressures, their ball pistons are rigidly connected to the connecting rod, wear plays a decisive role, because in this version force components from the connecting rod to the guide, d. H. on the line of contact between the ball piston and the cylinder bore, act and also the wear area is fixed locally.

There are already spherical pistons with rigidly connected connecting rods in axial piston machines known by using an inserted spherical expanding piston ring improve sealing and wear behavior.

However, spherical pistons with piston rings are for radial piston machines eccentric design not suitable due to the large deflection of the connecting rod.

The invention has for its object to be rigid with the connecting rod connected spherical pistons, especially for hydrostatic, low-speed radial piston machines in an eccentric design so that while maintaining or

Improvement of the advantages in terms of the technical effort and small construction dimensions the service life and the efficiency of the machine is increased, According to the invention, this object is achieved by the features listed in the claims solved.

The invention is described in more detail below using an exemplary embodiment explained. The drawing shows a section of the spherical piston assembly with the sealing ring.

The ball piston 2 rigidly connected to the connecting rod 1 is in a Cylinder bore 3 guided, to reduce the structural dimensions, the spherical piston 2 is at the front provided with a flat 4. In the center of the flat 4 there is one conical recess 5, the clearance of which is determined by the deflection of the connecting rod 1 will. The fluid is supplied to the not via the recess 5 and a bore 6 illustrated sliding shoe. In the recess 5, a pulling arm 7 is arranged, which is mounted achwenkbar by a -in Cr Kugelkelbenmitte fixzenden bolt 5. The @@@ anchor 7 takes a holder attached with a retaining screw 9 10 on, which is placed on the ball piston 2 by means of a compression spring 11 and in the cylinder bore 3 sliding sealing ring 12 is seated and through the The pressure effect of the fluid and the force of the compression spring 11 counteract the molded sealing ring 12 which seals the spherical piston surface and the cylinder wall. The fluid supply and -Discharge in the cylinder space 13, which is closed pressure-tight by the ZVlinderdeckel 14 is done via channel 15.

The mode of operation of this arrangement is as follows: Located in the cylinder space 13 the working pressure increases, the molded sealing ring guided in the cylinder bore 3 becomes 12 pressed against the surface of the ball piston 2 in a sealing manner. The Sealing ring 12 centering at the same time due to the force relationships present on the ball piston 2, so that the wear between the ball piston 2 and cylinder bore 3 is decreased. Due to the resulting direction of movement of the molded sealing ring 12 to the contact surfaces of the spherical piston 2 and the cylinder bore 3 results a functionally reliable seal, when depressurized or when there is negative pressure in the cylinder chamber 13, the sealing ring 12 becomes through the hold-down device which is under the pressure of the pedal 11 10 held in a stable position, the deflection of the connecting rod 1 and thus the pivoting movement of the spherical piston 2 is via the tie rod 7 and pivoted in the bolt 8 compensated for the hold-down device 10 attached to it, for special applications, z, B, when the stroke movement of the ball piston is relatively small, as is the case with positive displacement machines is the case with zero stroke, it can be advantageous instead of the holding device to arrange a compression spring in the cylinder chamber 13, which is once directly against the sealing ring 12 and on the other hand against the cylinder cover 14 is supported.

Claims (4)

Patent claims 41. Ball pistons for positive displacement machines, in particular for hydrostatic, slow-running radial piston machines in Eszenter design, g e k e n n z e i c h n e t d a d u r c h that between the cylinder bore (3) and the the spherical surface of the spherical piston (2) facing the cylinder space (13) is a sealing ring (12) is arranged, which is guided in the cylinder bore (3) and in its geometric Shape preferably the shape of the space that is formed between the cylinder bore (3) and spherical surface, and that the sealing ring (12) has a resilient Holding device is pressed onto the spherical surface. 2. Ball piston according to claim 1, g e k e n n z e i c h n e t d a d u r c h that the sealing gate ring (12) from one, from the pivoting movement of the ball piston (2) independent, pre-tensioned hold-down device (10) on the EugeloberZ surface is pressed. 3. Ball piston according to claim 1 and 2, g e k e n nz e i c h n e t d a d u r c h that in the center of a flat (4) of the spherical piston (2) one preferably conical recess (5) is incorporated, in which by means of a in the center of the spherical piston fixed bolt (8) a tie rod (7) is pivotally mounted and the under the tension of a compression spring (11) holding the hold-down device (10) by means of a retaining screw (9) is connected to the tie rod (7). 4. Ball piston according to claim 1, g e k e n n z e i c h n e t d a d u r c h that as a resilient holding device in the cylinder space (13), between the molded sealing ring (12) and the cylinder cover (14), a compression spring is arranged.