This invention refers to a rotary coupling for transmitting electric current and fluid, especially compressed air.

Background Art

Devices of this kind are known, for example from the British patent specifications 1 202 648, 1 349 850, 1 440 866, the German patent specification 848 378, the Swedish patent spe¬ cifications 90 160, 128 275, 175 979 and from the Swiss pa¬ tent specification 397 810.

The disadvantage of these prior devices is that they cannot be adapted in a simple way for use together with an arbi¬ trary number of electric conductors.

Disclosure of Invention

The present invention aims at removing this disadvantage and refers to a rotary coupling which is primarily suitable to be used as a rotatable control handle-for working machines where the number of control lines may vary from one type of machines to another. The control conductors are electrically connected to switches, potentiometers etc. for controlling the working movements of the machine.

Brief Description of Drawings

Fig. 1 shows the rotary coupling according to the invention in ft tiir nπ-noctionnl viow (partially in a front view) and Pig. 2 shows a sectional view along the line II-II in Fig. 1_

Best mode of carrying out the Invention

In Fig. 1 the rotary coupling according to the invention is ^' shown to include an axle ^" 1 which, for example, may be stati nary mounted in a movable part of a working tool. The worki tool may be a small electric hoisting apparatus, for exampl The movable part may be a lifting beam, for example, which movable in elevation and which can be turned in the horizon plane. At the end of the lifting beam the rotary coupling a a pneumatically controlled gripping tool which grips the wo piece to be hoisted are in turn provided. The movements of the hoistin apparatus are controlled by electric motors which are gover by means of controls, such as potentiometers and switches, which have a fixed mounting on a housing 2 which surronds t axle and which is rotatably mounted on the axle by means of roller or ball bearings 3. The advantage of this arrangemen is that the operator can walk round the work piece without releasing the grip on the housing 2 on which the controls a provided. These controls are electrically connected by con¬ ductors, not shown, with current conductors 4, 5, 6 which conventionally include, for example, spring loaded carbons arranged on a holder 7 which is rigidly connected with the housing wall. The end of the axle has a sleeve 8 of insulti material mounted thereon. The sleeve has a through bore 9 coaxial with a through bore 10 in the axle. The sleeve has portion 11 of reduced diameter. This portion has a number o axially extending grooves made therein of which only groove 12 is shown in the drawing. The depth of the groove is less than .the wall thickness of the portion 11. The grooves exte from the end face 13 of the sleeve 8 up towards the axle. A number of through openings 14 connect the bottom surface of the grooves 12 with the bore 9. Alternate electrically con¬ ducting slip rings 15 and spacer rings 16 are threaded on t the portion 11 of the sleeve. Each slip ring has an insulat • electrically conducting connection strip 17 fixed thereto b soldering which is thus received in a respective groove 12.

The free end of each connection strip terminates substantia ly opposite the respective opening 14 and there is electric

ly connected with its own insulated electric conductor 18. The conductors 18 may be assembled into a cable 19 (Fig. 2) which passes through the bores 9, 10. With the arrangement described it is seen that the housing may be turned round the axle any number of revolutions while maintaining electric contact be¬ tween the current conductors 4, 5, 6 and the respective line 18.

Passing through the bores 9, 10 there is a hose 20 for trans¬ mitting a fluid, in the present example compressed air. The hose is threaded on to a nipple 21 and is held in place on the nipple by a clip 22. The nipple has a flange 23 which contacts the end face 13 of the sleeve 8. The nipple is fixed to the sleeve by screws not shown which pass through the flange 23 into threaded bores (not shown) in those portions of the end face of the sleeve which are left between the grooves 12. The • nipple has a throat 24 round which a sleeve 25 having an in¬ terior groove 26 is rotatable and tightly arranged by means of 0-rings 27. The nipple has a central axial bore 28 which terminates in a through radial opening 29 which communicates with the interior groove 26. A tube 30 or corresponding means connects the sleeve 25 with a fluid connection appliance (not shown) fixed to the housing to which appliance a fluid powe¬ red tool, in the present case a compressed-air powered gripp¬ ing tool, may be coupled. It is seen that the above sleeve- -nipple arrangement allows rotation of the housing any number of revolutions while maintaining fluid transmission between the hose 20 and the fluid connection appliance.

A sleeve 31 with an axial slot 32 relieves the cable 19 from tensile stresses. The sleeve has axial through bores the dia- meters of which substantially correspond to the diameters of the cable and hose, respectively. A radial groove 35 is made in the outer surface of the sleeve 31. A stop screw 36 is thre'aded into the wall of the axie and serves to squeeze the sleeve 31 against hose and cable as well as to keep the sleeve 31 in position in the upper portion of the bore 9.

Many varying modifications and variations are allowed within the scope of the basic idea of the invention. For example, more or fewer slip rings (and with these a larger or lesser number of grooves 12) may be provided. It is important for the invention, however, that a suitable number of slip rings and spacer rings can be thread on to the portion 11 of the sleeve, before they are thereupon fixed to the sleeve by mea of a washer 37 or corresponding means, whereupon the conduc¬ tors 18 are connected electrically, for example soldered at the end of the respective connection strip.

Industrial Applicability

The invention may preferably be used as a control handle of a hoisting apparatus. The invention is not restricted to th field of use but may be equally well used in connection wit working tools wherein electrical current and fluid are to b transmitted in a rotary coupling.