US1991308A - Blade of pumps or compressors - Google Patents

Description

Fe%. 52 W35. P. ZENS BLADE OF PUMPS OR COMPRESSORS Filed Jan. 18, 1934 5 particularly a gyratory or rotary movement about j Patented Feb. 12, 1935 BLADE or PUMPS on. ooMrREss'ons Pierre Zens, Paris, France Application January 1a, 1934, Serial No. 707,197

. In France January 30, 1933 3 Claims.

This invention relates to improvements in the blades of pumps or compressors of the type in which systems of blades or pistons receive a, variable movement, preferbaly in a cylinder, and,

the longitudinal axis of the latter. The chambers, bounded by the blades and the cylinder owing to the relative angular displacements moving the blades of the various systems'towards and away from each other, have a variable volume so as to ensure the admission and delivery of the fluid through ports obturated and uncovered particularly by the rims of the blades.

The speed of this apparatus is actually limited owing to the important alternate stresses exerted on the blades, thus frequently causing the latter to break in the region of the roots.

The present invention is adapted to remedy this serious inconvenience and secure the attain ing of high speeds of rotation.

The improvements forming the subject-matter a of the present invention, which more, particularly relate to blades rigid with the corresponding hub on a portion only of their length, mainly consists in reinforcing the section of the root of the blade in the region of the hub and in correspondingly diminishing'the overhanging portion.

The portion of the blade corresponding to the hub has a profile which is different from that of the overhanging portion, whilst preferably preserving the same width of rim, this difference being such that the corresponding faces of two adjacent blades of two systems can fit on each other notwithstanding the reinforcement of the hub and without increase of the total volume .of each blade.

The invention further relates to the following points: (a) the longitudinal thrusts are absorbed by abutments situated on the respective shafts of these blades, so that these abutments are subjected only to the relative rotations of the blades. (b) the movable device thus constituted is held by a single member adjusting its position in the cylinder.

A reinforcement at the point of attachment of the blades is thus obtained at the expense of the overhanging portion which serves only for covering the ports without modification of the rim and the distribution, and without creation .of prejudicial space. v

Owing to this reenforcement higher speeds of rotation are permissible. The increase of the moment of inertia of the root enables hubs of small diameters to be used and the angle to be given to the blades then depends only on the speed of admission of the fluid through the ports, by virtue of which they may be givena minimum inertia. Moreover, the use of light alloys can thus be resorted to, even for'the root of the blades and the hub, so that the hub be made in one piece.

.The invention also relates to a special arrange- 'ment of the inlet and exhaust ports, which conblade units of a device comprising two movable units.

Fig. 2 is a perspective view of the other unit combined with that illustrated in Fig. 1.

Fig. 3 is an elevation, in axial longitudinal section of a compressor constructed according to the invention.

Fig. 4 is a section, on a reduced scale, made according to lirieIV-IV of Fig. 3.

Fig. 5 is a section, on a reduced scale, made according to line V--Vof Fig. 3.

Fig. 6 is a diagrammatic view of the form of the. pump blades at their point of closest approach.

The compressor illustrated by way of example only, comprises two units having relative angular displacements. The male unit is constituted as shown inFig. 1; it comprises a shaft 1 andthree blades 2 rigid with this shaft on a portion only of their length. The female unit, illustrated in Fig. 2, is constituted by a tubular shaft 3 and by three blades 4 rigid with this shaft on a portion only of their length. These units are mounted, as indicated in Fig. 3, within a cylinder 5, the shaft 1 being fitted into the tubular shaft 3; means, of any suitable type, are provided for rotatively driving, with a variable movement, the shafts 1 and 3, in order to cause, in the known manner, the volumes of the chambers 6 to vary.

Fig. 1 shows more particularly in perspective view the value of the reinforcement .of the root.

If the blade was traced, in the known manner,

for a blade angle AOB, the root would be ab. If, on either side of A and OB, equal angles aAN=aAM=bBP=bBQ are traced, it will be seen that the root thus obtained'is QN greater the principle of this feature of the'invention to be more clearly understood.

The blades, whether they belong to either of and the blades can the two units, are subjected to equal stresses. If it is not desired to have a too large amount of metal on one of the units and to utilize under the best conditions the available spaces within the cylinder of the machine, it is necessary that all the blades should be similar from one unit to the other. The blades will therefore have equal widths at their periphery. Thus, in Figure 6, AB of the first unit is equal to BC of the second unit.

Whatever may be their shape, the blades must be symmetrical and, when their opposed faces touch each other, from one unit to the other, if OK and CY are their axes of symmetry, one has According to the known methods, the radial plane OB is adopted as junction plane of the blades. In this case, the width of the blades at the root is ab=bc. This width depends on the values of OB and of AB which, to a certain extent, are prescribed; ab or be can be insufiicient for resisting to the stresses under, consideration. In order to remedy this inconvenience, the root of the blades AB might be reinforced, in its portion connected to the hub, by wide fillets P, provided the portions of the blades BC are so shaped as to constitute overhanging portions, as illustrated, that is to say by cutting away their inner edges according to arcs of the circle P superposable on P.

The invention permits the reenforcement of the blades to. the maximumextent at their point of attachment to the hub. It substantially consists in locating the contact planes of the opposite faces of the blades in the theoretical planes Ad, Bd, Be, Ce, the points it and e being the, intersections of the axes OK and OY with the periphery of the hub. a

Under these conditions, it will be seen that the width of the roots of the blades, at the hub, is df, that is to say twice the theoretical width m-b of the known arrangements. The overhanging portions of the blades have for cross section the curvilinear triangles A d B.

This new profile causes the production of a longitudinal thrust of the gases against the blades.

The stresses due to the pressureare exerted on the triangles AMN and BPQ and are counterbalanced but partially by the pressures acting on the ends of the blades.- These thrusts are absorbed by abutments situated between the concentric shafts rigid with each unit. The displacement of the abutmentsis limited to the relative displacement of one shaft relatively to the other; This abutment device, included in the scope of the invention, allows the adjustment of the laterally play or clearance of the entire set of blades in the cylinder by means of a single member, preferably a double abutment combined with the extreme bearing of the inner shaft.

The thrust of the gases or of the fluid tends to drive the blades 2, rigid with the inner shaft 1, in the direction 3.! x, and the blades 4, rigid with the outer shaft 3, in the direction am. The interposition of roller or ball thrust bearings 10 between both shafts 1 and 3, annuls these transs lations and the adjustment of the position of the movable device in the cylinder 51's effected by the adjustment of the double thrust bearing 11 situated at the end of the inner shaft 1, this atUustment,,in the'exa'mple cited, being effected by means of ascrew-thread "provided in; the cylinand 4, instead of being in one piece with the shafts 1 and 3, can be rigidly mounted on the latter, as illustrated, through the medium of the hubs 1' and 3.

It will also be noted, according to the invention, that the inlet or exhaust ports 13 have edges which are oblique relatively'to the edges of the rims of the blades in order to obtain silent working, by regularizing the displacements'of the fluid.

The form of construction described and illustrated is given only by way of indication and not in a limiting sense. All modifications which do not alter in any way the main features above set forth and the desired result remain included in the scope of the present invention.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a pump or compressor having two systems of blades arranged in a cylinder to be subjected to relative angular displacements, each system comprising a hub with blades, carried by this hub and extending beyond the latter in overhanging position, an arrangement wherein the side faces of the blades in the portion attached to the hub as well as in the overhanging portion are not in radial planes of the hub, the faces of the portions attached to the hub forming between them an" angle less than the faces of the overhanging portions.

2. In a pump or compressor having two systems of blades-arranged in a cylinder to be subjected to relative angular displacements, each system comprising a hub with blades carried by this hub and extending beyond the latter in overhanging position, an arrangement wherein the-side faces of the blades in the portion attached to the hub as well as in the overhanging portion, are not in radial planes of the hub, the faces of the portions attached to the hub forming between them an angle less than the faces of the overhanging portions, the angle between the peripheral face and the lateral face of the portion of the blade attached to the hub being in principle the supplement of the corresponding angle of the.

overhanging portion and all the blades being similar so that the opposed faces of two adjacent blades are adapted to fit against each other.

3. In a pump or compressor having two systems of blades arranged in a cylinder to be subjected to relative angular displacements, each system comprising a hub with blades carried by this hub and extending beyond the latter in overhanging position, an arrangement wherein the side faces of the blades, in the portion attached to the hub as well as in the overhanging portion, are not in radial planes passing through the axis of the hub, the faces of the portions attachedto the hub forming between them an angle less than the faces of the overhanging portions, a double thrust bearing interposed between the hub of one of the systems of blades and a shoulder on the shaft of the other system-for absorbing the radial reactions 'of the compressed fluid on thesblades,

thrust bearings at one of the ends of the shaft of one of the systems, means for longitudinally'adjusting the said thrust bearing on the cylinder of the pump or compressor, the cylinder having ports inclined relatively to the peripheral edges of the blades for constituting inlet and exhaust PIERRE ZENS.

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