Servocylinder with an electric piston stroke limiting switch

Details Servocylinder with an electric piston stroke limiting switch Servocylinder with an electric piston stroke limiting switch

1987-10-06

1989-07-04

Garrett, Robert E.

Expansible chamber devices

With inspection window in expansible chamber wall portion

With lock

91 25, 91 42, 310339, 25112906, F01B 2526, F01B 3112

Patent

active

048439517

DESCRIPTION:

BRIEF SUMMARY
PRIOR ART

The invention is based on a servocylinder according to the preamble of claim 1. Arrangements of this kind are already known. They are constructed as single-acting or double-acting cylinders whose pistons can be acted upon by liquids or gases, particularly compressed air. The inlet and outlet of the pressure medium is controlled in such a way that the previous inlet is closed and the outlet is opened when the stroke end position of the piston is reached. Varous possibilities are known for measuring and determining the position of the piston of a servocylinder, particularly that in which the piston end position is reached. But all these known arrangements are relatively expensive, susceptible to interference or inaccurate. Thus, for example, a servocylinder, which is known from DE-PS No. 30 14 331, uses a diaphragm as an end position transmitter, which diaphragm is welded with the front wall of the cylinder and consists of high-grade steel, an actuating member which is carried by the piston is axially aligned with the diaphragm. The deformation of the diaphragm is converted into a position signal by means of a sensing device arranged outside the cylinder space. DE-OS No. 32 21 574 is concerned with a cylinder with an integrated electric signal transmitter which, in one embodiment form, comprises two insulated electric conductors which are held at different electric potentials and contact the piston surface in the stroke end position, the piston surface consisting of a conductive material.


ADVANTAGES OF THE INVENTION

In contrast, the servocylinder, according to the invention, with the characterizing features of claim 1, has the advantage that it detects the end position of the piston without movable parts and with a compact construction. With a tight sealing of the working space, an indication of the end position of the piston is achieved with accurate response time; this also functions in a reliable manner under heavy-duty use conditions, at high pressures and temperatures, and is practically free of wear. Moreover, an external voltage source for indicating the end position of the piston is dispensable. In addition, the aforementioned servocylinder can be further developed as a piezo-hydraulic or piezo-pneumatic regulating element distinguished by large regulating distances, short regulating times and large transmission of force. For this purpose, it is provided that the feed line for a pressure medium acting upon the piston open into the front wall of the cylinder, the feed line being sealed in the stroke end position by means of a portion of the end face of the piston, that the piston be held in its stroke end position by means of a force which is greater than force of the pressure medium acting on the partial surface of the piston, and that a piezoelectric converter, which is connectable with a voltage source, be arranged in the front wall of the cylinder, which converter expands in the displacement direction of the piston when voltage is applied and lifts its end face from the front wall of the cylinder. According to an advantageous embodiment form of the invention, a joint piezoelectric converter is provided for detecting the piston end position and for lifting the piston from the front wall of the cylinder. This converter is advisably constructed as a cylindrical member which is inserted in a borehole of the front wall of the cylinder, which borehole extends in the movement direction of the piston.


DRAWING

An embodiment example of the invention is shown in the drawing and explained in more detail in the following description accompanied by the presentation of other advantages. The drawing shows a schematic presentation of a servocylinder with the respective control devices in a longitudinal section.


DESCRIPTION OF THE EMBODIMENT EXAMPLE

The drawing shows a servocylinder 1 with a piston 2 which is acted upon on both sides, is reciprocated along a linear stroke distance and can be reversed after its end positions are reached. The cylinder 1 is closed on both sides so as to be sealed a

REFERENCES:
patent: 2975119 (1961-03-01), Emmons
patent: 2983922 (1961-05-01), Juilfs
patent: 3027876 (1962-04-01), Strick
patent: 3598506 (1971-10-01), O'Neill
patent: 3758827 (1973-09-01), Schroder et al.
patent: 4584980 (1986-04-01), Weiger et al.
patent: 4610426 (1986-09-01), Brandner
"Piezoelectric Ceramic Transducers", Electronic Design, 9/74.

Affiliated with

Also associated with

Rating

Servocylinder with an electric piston stroke limiting switch does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Servocylinder with an electric piston stroke limiting switch, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Servocylinder with an electric piston stroke limiting switch will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-843970