FR2515754A1 - INSTALLATION BY GAS BEARING OF CONSTRUCTION ELEMENTS MOVING IN RELATION TO EACH OTHER - Google Patents

Abstract

A. GAS BEARING ASSEMBLY OF CONSTRUCTION ELEMENTS MOVING IN RELATION TO ONE ANOTHER. B. CHARACTERIZED IN THAT AT LEAST ONE CONSTRUCTION ELEMENT 1 INCLUDES AT LEAST ONE LEVEL 2 ELEMENT PERMEABLE TO GAS IN POROUS MATTER, GAS 4 CAN BE SENT TO INSIDE 3 OF THE BEARING THROUGH THIS PERMEABLE ELEMENT. C. MOUNTING APPLICABLE TO BEARINGS FOR HIGH AMBIENT TEMPERATURES.

Description

The invention relates to a gas stage mounting of elements of

  construction moving relative to each other, including air bearing mounting for extremely high ambient temperatures. The application of air bearings at high temperatures, most often with temperature gradients, leads, due to the high thermal expansion coefficients of the known materials, to variations in tolerances and consequently to known seizure problems, unstable market or has a sharp decrease in the coefficient of lift, To reduce the coefficients of dilation as well as the tolerances,

  it has often been proposed to use a ceramic material -

  special high compactness for the movable element to be mounted (for example shaft, piston) as well as for the element of

bearing (eg pad).

  In a conventional air bearing arrangement, it is necessary to provide inside the bearing to establish the appropriate air bearing cushions, small air supply holes and air distribution housings or ducts. execution of holes in the ribs

  wanted in ceramics as well as ducts of dis-

  Air tribution is extremely complicated and very expensive.

  It is therefore difficult to sustain from an economic point of view. The object of the invention is to create a gas-bearing arrangement of building elements moving relative to each other, this assembly avoiding the drawbacks mentioned above. In particular, it is necessary to obtain a simple and satisfactory assembly of construction. building elements exposed to conditions

extreme service.

  To this end, the invention relates to an assembly of the above type, characterized in that at least one construction element comprises at least one porous material permeable gas bearing element, the gas being able to be sent inside. from the landing through this element

permeable.

  The bearing element is made up

  Sintered porous ceramic material having a low coefficient of thermal expansion, the conjugate bearing element being made of high compactness ceramic material or metal (or other resistant material). The use of a sintered porous ceramic material makes it unnecessary execution of small air supply holes and air distribution housings that were necessary according to the state of the art The gas brought is

  on the contrary, sent to the interior of the landing

  distributed over the entire porous surface of the bearing, so that there is practically

  without contact with a defined bearing set.

  It is clear that this simplifies the manufacture of the bearing and that we obtain in addition also a

  increase of the capacity of the landing: the dynamic behavior

  In particular, it is considerably improved and a higher coefficient of lift is obtained with reduced gas consumption. The bearing is suitable for low temperatures as well as for very high temperatures (above 1000 ° C), as well as for high speeds. high relative values between building elements moving relative to each other (high rotational speeds of bearing-mounted shafts, high piston travel speeds).

  According to a particular embodiment

  of the invention, in a combined radial and axial bearing, at least one porous ceramic pad having a peripheral collar is provided

  to support the Axial Force.

  More particularly, the radial dimensions of peripheral flanges of opposed bearings (surfaces perpendicular to the axis of the porous bearing) are

  chosen of different size and / or adjustable for corre-

  weight to an axial thrust compensation By l Vaugmen-

  tation or reduction of the bearing surfaces in the axial direction of the bearing,

  unilateral axial thrust on the rotating element.

  Alternatively, the axial compensation can also be effected by biasing with different gas pressures from surfaces perpendicular to the opposite axis of the pad or pads.

  two separate pressure connections.

  It is advisable that the surfaces

  diculaires to the axis have radial slots for

  ensure that the gas cushion of the

  The radial slots have the advantage of being more economical than drilling,

  example in a ceramic material.

Air is advantageously used

  as a gas The air is sent to a pre-

  determined inside the bearing Depending on the case, we can provide air (or gas) hot or cold It is advisable that the gas is sent

  from an outside gas source.

2515 '754

  In the case of a compressor, however, it is advantageous for the gas to be sent inside the bearing from the compression chamber, provided that the piston compressor comprises the porous bearing element. The arrangement according to the invention

  of a non-contact porous bearing arrangement is particularly suitable

  for an aerostatic or aerodynamic air bearing, the bearing elements which are movable relative to one another are constituted, on the one hand, of porous ceramic material and, on the other hand, of ceramic material of high compactness.

  Air bearing is suitable for extreme temperatures.

  high and extremely low in conditions of

  constant or variable temperature at rotational speeds

  and / or with oscillating movements.

  air or gas is applied in front of a porous pad,

  judiciously through an annular chamber.

  The description below and the drawings

  Attached are examples of embodiments of the invention, in which: FIG. 1 shows an air bearing arrangement according to the invention for a ceramic shaft; FIG. 2 represents a combined radial and axial bearing according to the invention for a turbo-compressor; FIG. 3 is a cross-section along the line A-A of the combined radial and axial bearing according to FIG. 2; FIG. 4 represents a mounting by

  air bearing according to the invention of an element of con-

  reciprocating truction, for example a compressor or motor piston; Figure 4a shows another embodiment of an air bearing assembly of a compressor or motor piston; FIG. 5 is an axial section similar to FIG. 4 of a radial air bearing assembly

  according to the invention of a piston.

  The air bearing shown in Figure 1 is provided for a ceramic shaft 7

  performing rotational movements as well as movements

  oscillation elements The ceramic shaft 7 is

  subjected to a relatively large lift (radial) force

  This force is supplied by the outer bearing element 1 in the form of a housing removably fixed by screws 11 on the construction element 1c. In the bearing element 1 is geometrically mounted a porous ceramic gas permeable bearing element 2, this element surrounding the shaft 7 of high compactness ceramic material with a small clearance in fitting L-air is sent, from an external pressure source not shown, by a radial orifice of the bearing element 1, to an annular chamber 9 formed by the elements 1 and 2, this chamber extending axially substantially over the entire length axial of the porous bearing element 2 From

  of the annular chamber 9, the compressed air arrives at

  3 in the bearing (bearing slot) through the pores of the bearing element 2 In operation, this air is evacuated laterally into the atmosphere via axial orifices 6 o The supply air creates a carrier air cushion at the inside 3 of the bearing, so that there is practically no contact between the ceramic shaft 7 and the porous bearing element 2.

  the dynamic behavior of tree 7 in terms of

  compared to the behavior according to the state of the art, and a coefficient of

  higher lift (lower air consumption).

  The shaft 7 made of ceramic material

  high pacity and the porous bearing element 2 of sintered ceramic material have substantially the same (low) coefficient of thermal expansion It is thus possible to have both very low temperatures and very high temperatures up to 10000 C, with guidance of

accurate landing.

  The exemplary embodiment shown in FIG. 2 and FIG. 3, corresponding to a radial and axial bearing assembly, for a turbocharger, comprises a shaft 7 of conventional sintered ceramic material of high compactness. The bearing element 1 surrounding the shaft 7 of ceramic material maintains two porous bearing elements 2 essentially similar to each bearing element 2 comprises

  a peripheral flange 8 directed radially towards the ex-

  These flanges constitute mounting surfaces

perpendicular to the axis.

  In operation, air is sent to

  annular molds 9 by two separate inlet ports 4.

  From there, the air is sent to the bearing interval.

  In each of the two bearing intervals is established a uniform carrier air cushion, as well as on the surfaces

  perpendicular to the axis of the peripheral flanges 8.

  From the interval, the (primary) air is evacuated into the environment by the gas outlets 6 of the bearing element 1 The surfaces perpendicular to the axis of the peripheral flanges 8, have radial slots 5 (Three in number) regularly distributed around the periphery These slots are shown in detail in Figure 3; they serve

to ensure the evacuation of the air.

  It is preferable to carry out a

  compensation for unilateral axial thrust

  reduction or reduction of one of the supporting surfaces

  The axis of the porous bearing element 2 is also compensated for. One-sided axial thrust is also compensated when the individual bearing elements 2

  the air at a different pressure with a predetermined value

  Thus, it is possible to adjust the "hardness" of the carrier air cushion in the radial direction differently and to adjust the unilateral axial thrust accordingly. FIG. 4 shows an air-bearing arrangement for a construction element 7 moving in a reciprocating motion. (for example a piston of a compressor or a motor) The piston 7 is then constituted

  ceramic material of high compactness.

  The cylinder of the piston is formed by the bearing elements 1 of ceramic material of high compactness as well as by the building elements 1a, 1b.

  in the same composition and by the construction element

  When they are mounted, these elements maintain by their shape the porous bearing element 2 ceramic material (ceramic pad) The porous pad 2 then surrounds the piston 7 ceramic material following a

fitting fit with a weak game

  In operation of the piston compressor shown, gas 4 is supplied to the interior 3 of the bearing from the annular chamber 9 and through the

  porous cushion 2 The air is brought into the annular chamber

  9 From 10 (compressed gas) through the bore 4 A carrier air cushion is therefore built in ("Radial air bearing") Air can be removed, for example, without pressure below the piston 7 Due to the throttling effect of the porous ceramic material, the air consumption is relatively low, so that the pressure drop in the annular chamber 9 is of secondary importance. piston 7 shown in Figure 4 is moved downward, the expansion of the air,? At first, without pressure, is prevented because of the low air volume in the pores of the porous pad.

  2, there is a rapid establishment of the air pressure,

  which allows a very high axial stroke frequency of the piston compressor The axial orifices 12, 13 correspond to the intake and discharge of the compressor.

  In the exemplary embodiment of compres-

  According to FIG. 4a, the compressed air leaving the compression chamber 10 arrives via holes 4b of the element of FIG.

  porous bearing 2 in the annular chamber 9.

  The exemplary embodiment shown in FIG. 5 essentially corresponds to the exemplary embodiment according to FIG. 4. The corresponding elements are assigned the same numerical references. By contrast with the embodiment mentioned above, the step-by-step assembly radial air according to Figure 5 comprises a bushing 7 of high compactness sintered ceramic material, while the piston 14 of the compressor, whose base is made of high compactness ceramic material, comprises a porous and sintered cylindrical bearing element 2 which determines the interior of the landing 3 together with the

pad 7.

  In operation, in accordance with the right half of FIG. 5, air 4 coming from an external pressure source, not shown, is sent to the annular chamber 9 via a connection 15 of the crankshaft of the piston 14 of the compressor From from there, the air is conducted inside the bearing 3 through the bearing element 2 made of porous ceramic material. There is a carrier air cushion uniformly arranged on the lateral surface.

  cylindrical piston 14 of the compressor.

  Alternatively, in accordance with the left-hand half of FIG. 5, it is possible to have a direct pressure bias, from the compression chamber 10, through the bore 4. It is thus possible, advantageously, to dispense with 3 C. outdoor supply of hot or cold compressed air 3 <

15754

Claims (10)

  1 Gas-bearing arrangement of building elements moving relative to one another, characterized in that at least one construction element (1) comprises at least one gas-permeable bearing element (2) in porous material, the gas (4) can be sent   inside (3) of the bearing through this permeable element.   2 Assembly according to claim 1, characterized in that the gas-permeable bearing element (2) consists of a sintered porous ceramic material   having a low coefficient of thermal expansion.   3 Assembly according to one of the claims   1 and 2, characterized in that the conjugate bearing element (7) consists of a ceramic material of high compactness or metal.   4 Mounting according to any one of   Claims 1 to 3, characterized in that in a bearing   radial and axial combined, there is provided at least one porous pad (2) of ceramic material comprising a collar   device (8) to serve as support for the axial force.   Circuit arrangement according to Claim 4, characterized in that the radial dimensions of flanges   opposite pad peripherals (8) (perpendicular surfaces   to the axis of the porous bearing) are chosen   different and / or adjustable to correspond to a compensation axial thrust.   6 Assembly according to one of the claims   4 and 5, characterized in that axial thrust compensation is effected by biasing with different gas pressures from perpendicular surfaces.   at the opposite axis of the or pads.   7 Mounting according to any of the   Claims 4 to 6, characterized in that the surfaces   perpendicular to the axis have radial slots (5).   8 Assembly according to any one of   Claims 1 to 7, characterized in that the air is used as a gas -   9 Assembly according to claim 8, characterized in that there is provided an air bearing air bearing. Circuit arrangement according to Claim 8,   characterized in that an aerodynamic air bearing is provided   the bearing elements which are movable relative to one another (2, 7) are constituted, on the one hand, of porous ceramic material and, on the other hand, of ceramic material high compactness.   11 Mounting according to any one of   Claims 1 to 10, characterized in that the gas is   sent to the inside (3) of the landing at a predetermined temperature. 12 Assembly according to any one of   Claims 1 to 11, characterized in that the gas (4) is   sent from an outside gas source.   13 Mounting according to any one of   Claims 1 to 11, characterized in that in a   pressure, the gas is sent inside (3) of the bearing from the compression chamber (10) by holes (4 a) of the piston (14) of the compressor or by holes (4 b) 2.5   of the porous bearing element (2). ORIGINAL   Cabinet BERT, from y ER t YENANT & HERBURGF