DE1035412B - Ventilation device for the working cylinder of hydraulic telescopic shock absorbers - Google Patents

Description

The invention relates to a ventilation system for the working cylinder of hydraulic telescopic shock absorbers with a conclusion of the cylinder-forming guide for the piston rod.

The oil used to fill these shock absorbers usually contains a small amount of air. In the In the rest position of the shock absorber, the air separates from the oil and collects in the upper part of the Working cylinder or otherwise under part of the shock absorber, for example under the piston. However, this air cushion that forms has a disadvantageous effect on the operation of the shock absorber, since with the pressure fluctuations in the cylinder as the shock absorber works, the air expands or is compressed. The control valves therefore only open and close with a delay, and liquid slugs set in, which can often be heard as slapping noises. Through appropriate Formation of the individual parts and the arrangement of ventilation holes or the like. Can it is ensured that the air can collect under the upper end of the cylinder, from where it must then be derived. If the shock absorber is arranged vertically, the Air then escape through the gap between the piston rod and its guide. However, as the shock absorbers are often installed in an inclined position, it takes a long time to get the air that comes with the oil forms an emulsion, is squeezed out in this way. It forms at the 'highest point of the cylinder an air bubble which is then no longer in communication with the outlet, d. H. the play between the piston rod and their leadership, stäht.

In order to prevent such air bubble formation, it is known to follow the underside of the guide recess fully conical towards the piston rod. But since the length of these shock absorbers is limited Size is bound, such a conical recess leads to an impermissible shortening of the Guiding the piston rod in the cylinder closure and thus reducing the service life of the shock absorber. The basic angle of this conical recess has therefore been limited to 30 °.

In addition, it has already been proposed that the fully conical recess by several a part of the full cone forming grooves.

Despite these measures, an air bubble still remains when the shock absorber tilts Exceeds cone angle. In the horizontal position, the full size air bubble remains in the cylinder. These disadvantages are eliminated according to the invention in that telescopic shock absorbers with a venting device through an end cap of the working cylinder

for the working cylinder

of hydraulic telescopic shock absorbers

Applicant:

Aria Adrianus De Koning

and Kornelis Korstiaan Karel De Koning,

Oud-Beijerland (Netherlands)

Representative: Dipl.-Ing. E. Rathmann, patent attorney, Frankfurt / M., Neue Mainzer Str. 40-42

Claimed priority: The Netherlands, June 30, 1954

Aria Adrianus De Koning and Kornelis Korstiaan Karel De Koning,

Oud-Beijerland (Netherlands) have been named as the inventor

A venting device is provided on the protruding piston rod, in which the end cap in the part inserted into the working cylinder with opening out at the guide bore of the piston rod Vent holes are provided from one between the cylinder inner wall and the end cap located annulus. In this training, the air present in an airbag is immediately removed from the room at any time suctioned through a fine vent hole between the piston rod and the end cap. the Air suction is therefore more complete than in the known devices and independent of the respective location. In addition, the loss of area in the wall of the end cap is necessary for guidance the piston rod is used, less in the case of ventilation holes than in the case of a fully conical recess or in the case of grooves forming part of such a cone.

The new training is explained in more detail below with reference to the drawing. It shows Fig. 1 an axial section through the upper part of a shock absorber,

Fig. 2 is a cross section along line II-II of Fig. 1.

FIGS. 3 and 4 representations of a second embodiment and corresponding to FIGS. 1 and 2

■■ - ■ ': ■■ V 809 579/259

Fig. 5 and 6 the known design with the conical recess.

The upper ends of the working cylinder 1 and the envelope cylinder 2 of an otherwise known shock absorber are closed by a cap 3 which is screwed into the internal thread 4 of the envelope cylinder 2, for example. A disk 5 held by a threaded ring 6 produces the required seal. In a Axial bore of the cap 3, the piston rod 7 is guided and through sealing rings 8, which are held by a ring nut 9 are held, sealed.

In the known designs (Fig. 5 and 6) that protruding into the working cylinder 1 piece is the Cap 3 provided on the underside with a conical recess or inclined Xuten 10, which as Serve air collection space and the air through the gap 11 between the piston rod 7 and the cap 3 and feed radial bores 12 to the annular space 13 between the two cylinders 1, 2.

Xach the invention (Fig. 1 and 2) engaging in the working cylinder 1 piece of the cap is with an extension 3 a is provided, the diameter of which is smaller than the clear diameter of the cylinder 1. It thus remains between the cylinder 1 and the extension 3 a, an annular space 14, of which a row radial channels 15 are guided to the guide bore of the cap 3. The channels 15 can be to the axis the guide hole can also be inclined.

In the modification according to Figs. 3 and 4, the extension 3 a has the surface of a polygon, with the channels 15 extend from the corners of the polygon.

The air separated from the oil collects in the annular space 14 between the extension 3a and the Wall of the cylinder 1. When the shock absorber is working, the piston rod moves into the working cylinder, a pressure built up, which leads to an oil flow through the gap 11 between the piston rod 7 and the cap hole leads. When the piston rod is withdrawn, there is a gap 11 Pressure drop, so that there is a pressure difference in the channels 15, through which the air from the Annular space 14 is sucked off.

With the new design, the length of the guide of the piston rod 7 in the cap remains unchanged, so that the possible overall height of the cap 3 in this part is fully available for guidance and the surface pressure that occurs when the piston rod 7 is subjected to bending stresses in the Guide gap 11 is smaller than in the known designs.

The air accumulating under the cap 3 in the working cylinder 1 is even when it is horizontal Position of the shock absorber completely dissipated. After the air is discharged, the shock absorber will work with each stroke movement oil under pressure through the channels 15 from all sides to the piston rod and causes good lubrication of the piston rod in the guide, even if when the piston rod is subjected to bending stress, it is pressed against the wall of the guide on one side is, while in the known training in which the oil only in the axial direction after the guide gap reaches, such good lubrication is not guaranteed and the piston rod or the guide bore of the cap is quickly worn.

Claims (3)

Patent claims: 1. Ventilation device for the working cylinder of hydraulic telescopic shock absorbers with piston rod led out through an end cap of the working cylinder, characterized in that that the end cap (3) in the part (3 a) inserted into the working cylinder (1) vent holes (15) opening into the guide hole of the piston rod (7) is that of one located between the cylinder inner wall and the end cap Go out annular space (14). 2. Ventilation device according to claim 1, characterized in that the annular space (14) is narrow and that the vent holes (15) are perpendicular to the axis of the cylinder (1). 3. Ventilation device according to claims 1 and 2, characterized in that the in the Working cylinder (1) inserted part (3 a) of the end cap (3) in cross section the shape of a Has polygons and that the ventilation holes (15) from the corners of this polygon out to the piston rod (7) (Fig. 3 and 4). 1 sheet of drawings 809 579/259 7.58