DE2161646A1 - Fluid operated actuator - Google Patents

Description

Applicant's file number: Docket LE 970 015

Fluid operated actuator

In pneumatic and hydraulic actuators where fluid energy is converted into mechanical motion are usually used as transducer elements piston, diaphragm or bellows are used. Particular problems arise here with regard to sealing, costs and service life, with the designs with membranes and bellows are generally cheaper, but in terms of their limited service life Items are often unsatisfactory.

The simplest structure is shown by actuating devices of the above-mentioned types Type with bellows, as these can be made from one piece and, as a bellows, a relatively large change in volume enable. However, the wrinkles are sensitive to prolonged use and eventually become in some places, especially at the outer edges, leaking, so that they have to be replaced. He is also involved in the manufacture of bellows The required manufacturing process is relatively expensive, which affects the price, especially in the case of small versions affects. Their production with uniformly thick wall thicknesses for reliable function also requires special skill

209828/0613

opportunity.

These disadvantages of the known pneumatic or hydraulic actuating devices are according to the invention by Avoid using a substantially tubular sleeve as a transducer element. The invention is characterized by a core part of flat cross-section with one located in the central area, by means of an axial bore in one of the End parts of a recess connected to a pressure line, onto which a flexible cuff is slipped, on the outside of the recess the element to be actuated rests in the area of the recess of the core part.

In the actuating device according to the invention, between the core part and the sleeve in the end parts of the core part a natural sealing connection is produced, which is very simple in terms of production technology by means of a thermal process can be improved. The core part in turn serves as a guide element for the cuff, according to a preferred one Embodiment the sleeve made of thermoplastic Consist of material and in the area of the recess of the core part have a bulge that can be pressed either inwards or outwards can. This training has the advantage that when actuated by supplying pressure medium through the middle part the cuff formed chamber has a substantially constant volume, so that there is a constant stroke for the to be actuated mechanical element results. The cuff is only changed between its two shape states, without that the material is exposed to significant stress.

Another advantage of the actuating device according to the invention is that the sleeve made of thermoplastic material due to its shape relatively large radii of curvature has, so that damage from breaks and cracks and the resulting leaks, as in the case of bellows

209828/0613

Docket LE 970 015

used to appear, are avoided.

Another particular advantage of the actuating device according to the invention results from the possibility of a rational Mass production. A preferred manufacturing process for this is that a the cross section of the core part corresponding rod material is provided with a plurality of recesses and then a thermoplastic sleeve is pulled up, whereupon the bulges are permanently formed in a compression mold with recesses and finally the individual core parts are cut off with the sleeve.

The invention is explained below with reference to the drawings in an exemplary embodiment. Show it:

Fig. 1 is a perspective view of a pneumatic

Actuator;

Fig. 2 is a longitudinal section along the line II-II

Fig. 1;

Fig. 3 is a cross section on the line III-III of Fig.l;

4 shows a diagrammatic individual view of a core part

les;

5 is a diagrammatic detail view of a cuff;

6 to 8 different process steps for production

the actuating device according to FIG. 1 in series production.

The in FIGS. 1 to 3 illustrated pneumatic actuator 10 consists essentially of one in FIG. 4 separately

uocket LL 970 015 209828/0613

core part 20 shown, over which a flexible sleeve 30 (Fig. 5) is made of thermoplastic, i.e. relatively inelastic material. In the middle area of the cuff 30 there is a bulge " 31 is provided, the dimensions of which correspond to a recess 21 in the central part of the core part 20. Corresponding the material for the cuff 30 can be the bulge 31 on the one hand assume the position shown in FIG. 5 and on the other hand the position shown in dashed lines in FIG Part of a chamber 32 is formed. In order to bring the bulge 31 into the latter position, compressed air is to be supplied to one Channel 22 connected to a line 11 at the end of the core part 20. The channel 22 is provided with a longitudinal bore 23 in the Core part 20 connected, which is opened through the recess 21, so that in this area the sleeve 30 by the supplied Compressed air can be "blown out".

According to FIGS. 1 and 2, a support 42 is fastened to the frame 43 by means of a screw 44, on which an actuating arm 40 is pivotably mounted by means of a pin 41. As shown in dashed lines in FIG. 2, the actuating arm 40 is raised by a certain amount by the "inflation" of the cuff 31, the W bulge 31 reproducing a certain volume for the chamber 32 due to the inelastic material of the cuff 30. On the frame 43, e.g. B. attached to the support 42, spring clips 45 are provided for holding the core part 20 on both sides. The upwardly directed inclined inner surfaces 46 of the spring clips 45 allow easy insertion of the core part 20 during assembly.

The shape of the core part 20 is shown in detail in FIG. 4. The two end parts 24 on both sides of the recess 21 have surfaces 25 due to their flattened cross-section the upper and lower side and laterally rounded surfaces 26. The length 27 of the core part 20 is large compared to the width 28, and within this rectangular shape, the recess 21 takes accordingly the dimension of the bulge 31 - a considerable-

Docket LE 970 015 209828/0613

2161648

_ 5 -

part.

The surface 21a of the recess 21 is also the actuating surface 47 of the actuating arm 40 adapted to which the pneumatic actuating force is effective when through the bore 23 compressed air is supplied. The two operating states of the cuff 30 can also be clearly seen from FIG. 3, the change in shape of the cuff 30 being greater than in one case and other case less flattened hose ensures that between the surface 21a of the recess 21 and the actuating surface 47 is always only a smooth layer of the material of the sleeve 30. Because in the unloaded state, the outer areas the bulge 31 of the cuff 30 evade outwardly without the actuating arm 40 hindering this.

The core part 20 can either be cast or machined will. If to simplify the production the hole

23 is formed continuously, the hole 23 must be on the opposite side of the pressure gap supply through a plug 23b be sealed.

The cuff 30 is dimensioned so that they are medium-tight for a Termination can be drawn onto the core part 20, for which the inner dimension approximately with the outer circumference of the end parts 24 of the core part 20 matches. To design the cuff 30 with the bulge 31, as mentioned, a relative is required inelastic material, for which thermoplastic material is particularly suitable. Basically, however, is for the cuff 30, a material of higher elasticity is also conceivable, the chamber 32 due to the supplied compressed air without the fixed volume limitation is formed by the bulge 31. In addition, the seal between the sleeve 30 and the end parts

24 of the core part 20 also by welding, for example at the point 33, by means of heating or by means of an ultrasonic method be improved. The assembly is carried out in a simple manner, initially by slipping the sleeve 30 onto the core part 20

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and then inserting both parts into the spring clips 45 on the frame 43.

The preferred method of mass production of the from the core part 20 and the cuff 30 existing element are shown in FIGS. 6 to 8 shown. Thereafter, according to FIG. 6 from a Rod material with a corresponding cross-section and a longitudinal bore 51 milled out a number of recesses 52 in the required distance and the desired length by means of a milling cutter 60 (The milling cutter 60 can also be used with opposite cutting and rotating directions). After this preprocessing a corresponding thermoplastic sleeve 54 is pushed so that it is on the unprocessed sections 53 between the recesses 52 rests in a medium-tight manner. By means of a compression mold 61 (FIG. 7) with a number of recesses 62 (in the area of the recesses 52) and heating elements 63 are then a firm connection between the sleeve 54 and the unprocessed sections 53 manufactured.

Before being inserted into the compression mold 61, the sleeve 54 can be heated so that it exhibits thermoplastic behavior. To the insertion into the compression mold 61 can then under the action of compressed air supplied through the longitudinal bore 71 or by application the bulges 31 are formed by vacuum in the recesses 62 and maintained by subsequent cooling. According to FIG. 8, a corresponding number of individual elements 55 for assembly in the is then obtained by means of a shear blade 64 pneumatic actuating device 10 according to FIG. 1.

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Claims (1)

PATENT CLAIMS Fluid operated actuator / featured through a core part (20) of flat cross-section with one located in the central area, by means of a axial bore (23) in one of the end parts (24) connected to a pressure line (11) recess (21) on the a flexible cuff (30) is put over, on the outside of which in the region of the recess (21) of the core part (20) the element to be actuated (40) is applied. Actuating device according to claim 1, characterized in that that the sleeve is made of thermoplastic material and in the region of the recess (21) of the Core part (20) has a bulge (31) that can be pressed either outwards or inwards. Actuating device according to claim 1, characterized in that that the element to be actuated as a pivotably mounted actuating arm (40) with a with the shape of the Recess (21) of the core part (20) matching actuating surface (47) is formed. Process for producing the device according to claims 1 and 2, characterized in that one with a central longitudinal bore (51) provided with rod material (50) corresponding to the cross section of the core part (20) a plurality of recesses (21) and then a thermoplastic sleeve (54) is pulled, that then in a mold (61) with recesses (62), the bulges (31) are permanently shaped and finally the individual ones Core parts (20) with sleeve (30) are cut off. Docket L, 970 015 209828/0613