FR2466640A1 - Single-cylinder reciprocating compressed-air motor - has rotary-disc control valve operated by piston rod via springs overcoming detents - Google Patents

Abstract

The single-cylinder reciprocating compressed-air motor has an extension of the piston rod projecting through the cylinder head into a pressure-tight chamber with an air inlet. Coaxial with the extension is a rotary disc valve in the form of an annular flat plate fixed to the cylinder head and a cup-shaped one free to slide over it. A winged sleeve rotated by a pin following a helical groove in the rotationally fixed rod extension operates the movable plate via peripheral springs, overcoming radial detents. This controls flow through a system of passages providing double-acting operation.

Description

The present invention relates to a compressed air engine provided with a cylinder casing and a lifting piston.

The present invention aims to allow the realization of a small compressed air motor of short stroke, provided with the essential reversing valve and of simple and compact construction.

To this end, according to the invention, the compressed air motor is provided with a rotary disc valve of the same axis as the piston, elastically linked in rotation to a propeller prevented from rotating forming with the piston rod a finger arrangement and helical groove. By finger arrangement and helical groove in the broad sense, we mean a non-self-locking thread, which transforms the movement
elevation of the piston rod in a rotational movement of the propeller, which in turn derives the jerky rotary movement of the valve disc, thanks to said elastic rotating connection which acts as a torque accumulator.

An advantageous finger and helical groove arrangement consists, for example, of helical grooves made in the control section of the piston rod and of fingers integral with the propeller and the respective internal ends of which are in engagement with said grooves.

According to another feature of the invention, the piston rod is integral with a diaphragm pump diaphragm and is thus made non-rotary by this fact alone. This arrangement is especially advantageous when the membrane has a diameter much larger than the piston, because with such a ratio, the membrane is sufficiently rigid to be able to withstand the rotational force exerted on the piston rod, during operation of the rotary disc valve.

Suitably, the rotary disc valve is arranged in a compression chamber extending behind the cylinder housing and connected to a compressed air supply, a piston rod control section penetrating inside said chamber. .

The rotary disc valve may consist of a valve disc integral with the front wall of the compression chamber and of a valve disc capable of pivoting between two stops and of engaging in extreme positions. In addition, preferably, the connecting conduits to the cylinder chambers supplied alternately with compressed air and the exhaust conduit passing right through the fixed valve disc, open into the compression chamber. The rotary valve disc has apertures and passage openings cooperating with the opening of said conduits. The rotary valve disc is pressed against the fixed valve disc by the supply air pressure prevailing in the compression chamber.

A space-saving, simple and reliable elastic connection in rotation can be obtained by providing a cylindrical rim for the rotary valve disc and by placing inside said rim, helical springs which circumferentially surround said rim and which bear at one end on the propeller and at the other end on tabs projecting towards the inside of said flange.

 I1 is advantageous to provide, as a rotary marking device, notches formed in the outer surface of the rim of the rotary valve disc and coooperative with balls pressed from the outside by radial springs. The pressure of said springs can be easily adjusted from the outside by means of an adjusting screw.

The invention will be clearly understood in the light of the accompanying drawings.

Figure 1 is an axial section along line I-I of Figure 2 of a compressed air motor according to the invention controlling an incorporated diaphragm pump.

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

FIG. 3 is an axial section along the line III-III in FIG. 2.

The figures show substantially on scale two, an engine according to the invention and its associated pump.

The diaphragm pump has an upper part 1 and a lower part 2 clamping a diaphragm 4 between them by screws 3. The space above the diaphragm 4 has two ventilation openings la. Between the lower part 2 and a suction nozzle 5 screwed below it, an elastic sheet 6 is tightened. This has two notches in the shape of an arc and in this way of the exposed tongues, which rest from the 'interior on bores 7 in the suction nozzle 5 and play the role of inlet valve flap. A radial exhaust nozzle 8, containing a ball valve, is screwed into the lower part 2 (see FIG. 1).

On the upper part 1, a cylinder casing 9 and a cover screwed with two screws 11 rest.

The cylinder casing 9 has a transverse wall and forms, between the latter and the upper part 1, a space in which a piston 12 is able to move in an alternating vertical movement. The piston rod passes through said piston. Its lower section 13 crosses the upper part 1 and is integral with the membrane 4. The upper section 14, said control, crosses the transverse wall and enters the compression chamber ~ 15 contiguous, said chamber being formed by the cover 10 provided with a compressed air inlet 16.

In the compression chamber 15 there is a valve disc 17 concentrically surrounding the control section 14 of the piston rod and being secured to the transverse wall of the cylinder housing by means of a countersunk screw 18. On the disc of valve 17 rests an annular valve disc 19 of L-shaped cross section. Said valve disc 19 is mounted slightly rotatably in the cylinder casing 9 and has a clearance relative to the cover 10. The flat surfaces of the discs valves 17 and 19 resting on each other are polished. A stop 20 (see FIG. 1) passing through the fixed valve disc 17 and projecting with respect to the upper face of the latter, penetrates into a lower recess 21 of the valve disc 19 and limits the rotation thereof to approximately 200.

FIG. 2 shows the device for marking the rotation of said valve disc 19. The cylinder casing 9 has on its outer square perimeter, two bosses 22 arranged diagonally opposite at the top of the chamber 15. In these bosses, are screwed. dies adjusting screws 24 provided with a slot for a screwdriver and locked by a lock nut 23. Pressure springs 25 are supported on said screws and exert pressure on snap-on balls 26 abutting against the outer surface of the cylindrical rim of the valve disc 19. Small positioning notches 27 are provided on said external surface and receive the positioning balls 26.

The rotary valve disc 19 is actuated by means of a double helix 28 integral in rotation with the control section 14 and comprising two radial fingers 29, the inner ends of which each penetrate a helical groove 30 disposed in said control section 14. The FIG. 2 shows two wedge-shaped cleats 31 pressed into two diametrically opposite cylindrical recesses and arranged on the inner edge of the valve disc 19. Between the cleats 31 and each contiguous arm of the propeller 28 are compressed respectively helical springs 32 and 33, fitting the cylindrical rim of the valve disc 19 and whose sliding relative to the propeller and the stoppers 31 is avoided by means of hemispherical studs 34 each arranged on the sides of the stoppers 31 and the arms of the propeller 28. The four springs helical 32 and 33 are identical.

Three conduits, arranged in the cylinder casing 9, pass through the fixed valve disc 17 by bores and terminate in chamber 15, while said bores are placed on the same arc. Despite the exact angular position of these conduits and mouths, which is not particularly shown, the figure shows an outlet conduit 35, a connecting conduit 36 exiting from the lower cylinder chamber (see FIG. 1) as well as a connecting duct 37 exiting from the upper part of the cylinder chamber (see FIG. 3).

The flat face of the valve disc 19 has at the bottom a lumen 38 connecting two mouths and two passage openings not shown.

The operation of the compressed air motor according to the invention is described below. In the position shown, the piston is in its extreme upper position. The position of the valves is such that the chamber 15 is supplied, at its upper part, with compressed air by the arrival of compressed air 16, by means of one of the openings for passage of the rotary valve disc 19 and by means of the connecting duct 37 of the piston 12, while the chamber at its lower part, is connected, by the connecting duct 36, the lumen 38 and the outlet duct 35 with the external atmosphere. The piston 12 then moves downwards. Thus the propeller 28 follows the helical pitch of the groove 30 in the control section 14 of the piston rod and moves, according to FIG. 2, in the clockwise direction. a watch. (In Figure 1, only the groove 30 is visible, and moreover, its layout is not shown in reality). The helical springs 33 therefore relax and the springs 32 are compressed together. A little before the piston 12 reaches its final lower position, the dextrorotatory moment acting on the rotary valve disc 19 is strong enough for it to leave its rest position and suddenly rotate to its other position, causing switching of the control conduit so that the piston 12 is again in an upward movement.

Note that the described application example of the compressed air motor according to the invention to a diaphragm pump is advantageous because the diaphragm 4 prevents rotation of the piston rod. This is advantageous because the membrane, in this case, is stable enough to resist the thrust of the springs. The compressed air motor must have, for other applications, a particular longitudinal duct preventing rotation of the piston rod.

The device shown is advantageous for introducing a fluid from a container into a network of conduits, from which it is removed irregularly. For example, for use in spray paint spraying installations, it is possible to connect to the suction nozzle 5 a tube immersed in a paint drum. The diaphragm pump then supplies a network of ring pipes for several spray guns, each fitted with a high pressure pump. When the guns are out of service, the diaphragm pump remains idle. As soon as a spray gun is actuated, and the paint is removed from the circular pipe, in which the pressure then decreases, the pump starts automatically and allows the said guns to be supplied with the corresponding flow rate.

Claims (7)

RESELL ICAT IONS 1- Compressed air motor fitted with a cylinder casing and a lifting piston, characterized in that it comprises a rotary disc valve (17,19), of the same axis as the piston (12), including the disc rotary (19) is elastically linked in rotation to a propeller (28) which is engaged by a finger arrangement and a helical groove with the piston rod, prevented from rotating. 2- Compressed air motor according to claim 1, characterized in that the rotary disc valve (17, 19) is arranged in a compression chamber (15), extending rearward the cylinder housing (19) and connected at a compressed air inlet (16), compression chamber into which a rear control section (14) of the piston rod enters. 3- Compressed air motor according to claim 2, characterized in that the rotary disc valve comprises a valve disc (17) integral with a front wall of the compression chamber and a valve disc (19) capable of snap into extreme positions and rotate between two stops (20), while connecting ducts (36,37) to the cylinder chambers and the exhaust duct (35) pass through said fixed valve disc (17) and open into said compression chamber (15), the rotary valve disc having lights and passage openings (38) cooperating with the opening of said conduits. 4- Compressed air motor according to claim 3, characterized in that the rotary valve disc (19) has a cylindrical peripheral rim and in that the rotating elastic connection consists of helical springs (32,33) adapted circumferentially to said rim, said springs bearing at one of their ends on said propeller (28) and at the other end on tabs (31) projecting towards the inside of said rim. 5- Compressed air motor according to claim 1, characterized in that said finger arrangement and helical groove comprises helical grooves (30) formed in the control section (14) of the piston rod and of the radial fingers (29 ) provided on a propeller (28) and engaged by their interior ends with said grooves. 6- Compressed air motor according to claim 3, characterized in that it comprises a rotating marking device (24), adjustable as to the elastic pressure which it exerts, provided with balls (26) bearing radially from the outside on the edge of the rotating disc. 7- Compressed air motor according to one of the preceding claims, characterized in that the piston rod (13,14) is integral with a diaphragm (4) of a diaphragm pump and is made non-rotary from this only fact.