FR2532995A1 - PUMP EQUIPPED WITH A PISTON AND A SLIDING RING - Google Patents

Abstract

THIS PUMP IS OF THE TYPE IN WHICH THE PISTON IS ISOLATED FROM THE CRANKSHAFT CHAMBER BY A SLIDING SEALING SEAL WHICH LIES AGAINST THE PUMP CYLINDER. ACCORDING TO THE INVENTION, PUMP 1 INCLUDES AN OSCILLATING PISTON 2, IN PARTICULAR ONE OF A SINGLE PIECE WITH THE CONNECTING ROD 4, WHICH PRESENTS A SEALING SLEEVE 11, WHILE A SEALING MEMBRANE 13 IS INTERPOSED BETWEEN THIS SLEEVE 11 AND CHAMBER 12 OF THE CRANKSHAFT.

Description

Pump fitted with a piston and a sliding annular seal.

  The invention relates to a pump, the piston of which is hermetically isolated from the crankcase by means of a sliding seal which bears against the cylinder of the pump. Pumps of this kind are known, for example in the form of plunger pumps The separation between the

  delivery chamber and pump crankcase

  pe is usually ensured by seals

  ity sliding annular Pumps of this kind still have many drawbacks For example, there is a risk of pollution of the fluid to be pumped by the lubricant or by lubricant vapors Furthermore, there is the risk that, for example, the fluid to pumping, which can be aggressive, penetrates into the region of the lubricated drive members. In this regard, it is the lubricant of the bearing

  the piston pin which is particularly endangered.

  joust the fact that the spans of the piston pin are

  close to the discharge chamber and, therefore, can

  may also be exposed to overheating In addition, the sliding ring seals used

  in these plunger pumps do not offer a seal-

absolute ity.

  Furthermore, oscillating piston pumps such as that described in US Pat. No. 3,961,869 are known. In these pumps, the piston and the connecting rod are in one piece.

  piston therefore accompanies the oscillating movement of the connecting rod.

  Oscillating piston pumps of this kind certainly avoid the use of a piston pin and the problems associated therewith. However, in this case there is also no entirely sealed separation between the

  discharge and the crankcase or between this

  bre and the lubricated parts of the pump; on the contrary, the formation of a tight seal on the oscillating pistons is problematic because of the oscillating movement of the piston which

has just been mentioned.

  Separation between pump volumes entering

  in contact with the fluid to be pumped and the crankcase-

  brequin, etc, is particularly important in the case of "dry piston machines" This expression is understood

  pumps or compressors in which the moving parts

  those that come into contact with the fluid to be pumped do not have to be lubricated, so that the fluid to be pumped does not risk absorbing small amounts of lubricant or equivalent. To obtain a compressor for gaseous fluid or a pump for liquid fluids in which or in which the fluid to be discharged is prevented from reaching the mechanism to

  connecting rod-crank, we used until now

  Stocks with buttstock drive Here, the piston and the rod

  corresponding piston only describe linear movements

  alternative areas and the rod is sealed in isolation by a cable gland However, this embodiment still has great drawbacks, in particular the drawbacks specific to cable glands The cable gland

  does not provide complete tightness and requires monitoring

  launches and constant maintenance Furthermore, if the pump

  remains idle for a long time, the packing of the cable gland

  than to adhere to the piston rod of the pump to the point of

  cause damage during start-up.

  In addition, pumps or compressors fitted with a drive

  stock are expensive, both in construction and in operation; usually they cannot be used

  only as slow machines and in practice they are only used

  only for large machines When studying

  such compressors or butt pumps intended for work-

  ler with dry piston, one must also choose accordingly the materials to be used for the cylinder liner, the piston rings, etc., so that one is limited, in this

  which concerns the choice of materials, by the risk of re-

  action between the materials and the fluid to be pumped.

  The problem therefore arises of creating a pump of the

  aforementioned kind in which the fluid to be discharged is her-

  metrically isolated from the crankshaft chamber or equivalent with watertight seal while maintaining a construction method

  simple and, to a large extent, avoiding the disadvantages

nients of pumps already known.

  At the same time, the pump must in particular be

  also able to work in a dry piston machine. The solution according to the invention consists in particular

  in the fact that in a pump with a sealed piston

  tically isolated from the crankshaft chamber by a gasket

  sliding sealing structure which bears against the pump piston, by the fact that an oscillating piston is provided which carries a sealing sleeve as a seal

  waterproofing and by the fact that in addition, a mem-

  sealing brane is provided between this sealing sleeve

  chequity and the crankshaft chamber Certainly already known are diaphragm pumps for gaseous or vapor phase fluids which comprise one or, in particular, two membranes (see patent application of R Fo A DE-AS 25 02 566) However, in the case of diaphragm pumps, the length of the stroke

  of the p 9 mpe as well as the value of the discharge pressure

  are limited If, any other conditions (e.g.

  full delivery volume, rotation speed) remaining equal

  we want to push back a given quantity of fluid, we can certainly get this result by increasing the diameter

  of the discharge chamber, with a limited stroke in con-

  sequence However, this entails the disadvantage that the pump must have dimensions which are all the greater, the more the bearings have to bear pressures

  and therefore the pump is relatively cost-effective.

teuse and subject to wear.

  On the contrary, in the case of the subject of the invention, it is possible to avoid, on the one hand, the drawbacks of butt-driven pumps, on the other hand, the risk of dilution of the lubricant present in the piston pumps diver and ultimately the disadvantages or limitations of

  diaphragm pumps This pump can also be used

  so well for the delivery of liquids as for that of gases, in particular when the fluids to be driven back are aggressive In these constructions, one can use for the

  sealing sleeve and, if necessary, for the mem-

  sealing brane, materials with high resistance

  tance to chemicals and oxidation, such as polytetrafluorethylene One can also obtain a dry running safety of the oscillating piston so that, on the one hand, there is no risk of pollution of the fluid discharged by the lubricant and, on the other hand, destruction

  lubricant in the connecting rod-crank mechanism of the pump

  pe Thanks to the sealing membrane, the separation between the pump components which come into contact with the medium to be pumped and the area of the mechanical drive of the pump is absolutely free of leaks and is practically not exposed. significant wear The pump according to the invention therefore combines the essential advantages of pumps of the type already known without being affected by the serious drawbacks of these pumps. In particular, relatively small pumps can also be constructed having a piston diameter.

  reduced and in which the bearing load is not

  not too big This favors obtaining a long longevity. An important improvement of the invention consists

  in that the intermediate chamber between the

  seal ity 6 ity and the waterproofing membrane is connected

  In this way, the fluid to be discharged

  The leaking part along the sealing sleeve can thus be evacuated from the intermediate chamber.

  of a liquid fluid, this fluid can be evacuated in this way

  lesson by simple means A preferred form of realization

  tion of the invention is that the intermediate chamber

  diaire is connected to the suction pipe of the pump by a drain pipe In this way, there is no pumped fluid lost or rejected in the free atmosphere but on the contrary, the fluid is automatically reinjected in

the repressed current.

  The aforementioned drain line or recycling, for example in the suction line of the pump, is ensured by the fact that it cannot accumulate between the

  sealing sleeve, on the one hand, and the waterproofing membrane

  on the other hand, a quantity of fluid to be discharged such that a pressure is established in this space. Indeed, this pressure could reduce the tightness of the sealing sleeve.

  Another advantageous embodiment of the pump

  pe is that the waterproofing membrane is suitable

  the stroke of the piston, preferably thanks to a narrow width

  larger dial of its assembly area For example, in the case of a large stroke of the oscillating piston, the diameter of the freely movable region of the sealing membrane can be greater than the diameter of the cylinder In this way, we can prevent the waterproofing membrane from having to

  undergo unwanted dilations or other constraints a-

nalogues.

  It is advantageous, especially when the pump is working

  value with an overpressure of supply in the suction pipe, that the oscillating piston presents a support flange for the waterproofing membrane The pressure of the fluid to be pumped which acts on the waterproofing membrane is then

  supported by this support flange.

  Another advantageous improvement of the invention

  consists of a combination of the pump presenting

  aforementioned characteristics, in which, in the case of a sealing cuff which comprises a cuff part

  extending approximately radially and which is at least partly

  partially held by the actual piston part of the piston

  oscillating tone as well as a lip region which is supported at

  tight seal against the cylinder wall, the thickness of pa-

  king of the roughly stretched portion of the cuff

  dialing being greater than the wall thickness of the

  sealing sleeve lip region In this form-

  construction, the oscillating piston still benefits

  secure guidance, even when the lip region is already thin

  through wear This reduces the risk of damage to the

  pump cylinder and overload of the diaphragm.

  chéit 6 Furthermore, according to another characteristic avan-

  tagger of the invention, the free internal width of the pump cylinder is of slightly reduced diameter

  in the middle region of the piston stroke, compara-

  tiver'ent to the maximum cylinder diameter.

  In this way, the slot that the sealing cuff-

  ity must cover without support can be slightly reduced in the area of the steepest inclination of the pump piston The tightness on the sealing sleeve is improved by the same amount, so that the efficiency of the pump is also improved and that the risk of overloading the

  waterproofing membrane is reduced.

  The invention is described below in more detail

  about several examples of realization and in ref 6-

  Reference to the drawing, drawn on variable scales and in the-

  which: Figure 1 is a side view with partial section of a pump comprising an oscillating piston, a sealing sleeve and a sealing membrane; Figure 2 is a view similar to Figure 1 on which

  a support flange has been provided for the waterproofing membrane

cheeness;

  Figure 3 shows a sealing sleeve in form

  cup me; Figure 4 is a partial elevational view, in part

  in section, similar to FIG. 1, comprising a sleeve of

  slightly modified sealing compared to FIG. 2; and Figure 5 represents, in a very diagrammatic form,

  a slightly choked diabolo pump cylinder.

  A pump, designated as a whole by the reference

  (1) comprises a piston-rod (2) This is understood to mean

  pressure the fact that the piston part proper (3) and the connecting rod (4) are made in one piece This connecting rod

  swivels, by its eye (5), on the eccentric (6) of the vi-

  lebrequin rotating around the axis (7) (see in particular Figure 1) The oscillating piston therefore accompanies the oscillating movement of the connecting rod (4) As a result, it can occur in particular in the central region (8) of the

  stroke (H) of the oscillating piston (2) (see in particular fig.

  gures 1, 4 and 5), leaks between the part

  piston (3) and the wall (9) of the cylinder (10) of the pump.

  In the case of the pump (1), it is now seen, on the oscillating piston (2), as a sliding seal, a sealing sleeve (11) and, in addition, a diaphragm d seal (13) is additionally mounted between

  this sealing sleeve (11) and the chamber (i 2) of the vi-

  lebrequin The fluid to be pumped which still passes through the leaks between the sealing sleeve (11) and the wall (9) of the cylinder (10) of the pump is isolated with certainty from the chamber (12) of the crankshaft by this membrane- sealing

  (13) In this way, we are certain that the fluid to

  ler, which can be, for example, an aggressive fluid, does not risk

  that no deteriorating the lubrication of the vile chamber-

  brequin The pump (1) can thus also be used as a "dry piston" pump, that is to say that the fluid to be pumped does not come into contact with the lubricant which is necessary

  for pump operation The sealing membrane

  tee (13) is tight 6 e with tight seal on the piston part (3) of the oscillating piston (2) in its r 6 central region (14) For this purpose, the rod (15) of the piston has a support base

  (16) which protrudes from the fixing stud (17) intended to receive

  see a lower clamp (18) Above the

  lower clamping piece (18) is the

  seal (11) in the form of a cup, which is fixed by

  on the swing piston (2) by means of a clamp

  upper rage (19) The clamping parts (18) and (19) form

  to a certain extent the piston part (3) These parts

  these (18) and (19) are assembled to the piston rod (15) at

  using a screw (21) which is accessible through the chamber

  pump discharge bre (20) (1) As can be

  see particularly well in Figures 1 and 2; the mem-

  sealing brane 6 ity (13) is fixed to the crankcase (23) or to an equivalent part 6 of the pump by its outer edge (22) This part of the pump can also be constituted, for example, by the cylinder (10) of the pump,

  as shown in Figure 4 In this case, the membrane of-

  sealing (13) is mounted near the sealing sleeve

  sealing (11) This has the advantage that the movements that the sealing membrane (13) must perform to follow the movements of the piston part (3), do not impose stresses detrimental to the membrane. sealing (13) which is usually very flexible The intermediate chamber (25) which is located between the sealing sleeve (11) and the sealing membrane (13) and which is closed laterally by the wall (9) of the cylinder, is provided with a drain pipe (24) which leads outside through the cylinder (10) of the pump Si, for example

  in the case of a pump (1) delivering a liquid, a small

  te quantity of liquid to be returned reaches the intermediate chamber (25) by leaks along the sealing sleeve (11), this liquid does not accumulate in this chamber and does not deteriorate the sealing but this liquid

  leak can flow through the drain pipe (24) This drain

  Lement can flow, for example, in the vacuum tank

  ration or in the free atmosphere In the case where it is a question of compressing air or equivalent gases which do not pollute the environment, one can proceed in a similar way with gaseous fluids However, a particularly

  advantageous embodiment of the invention consists in connecting

  from the drain pipe (24) to the suction pipe

  (28) of the pump (1) via a return line

  cycling (27), as shown schematically in Figure 1 In this way, the liquid or the leaking gas which enters the intermediate chamber (25) is sucked into

  this chamber and returned to the pump discharge circuit.

  As already described above, the parts above

  lower and lower piston (19) and (18) respectively

  can be dismantled by operating through the discharge chamber -

  ment (20) It is the same for the sealing sleeve (11) and, after having disassembled the cylinder (10) from the pump, the sealing membrane (13) can also be removed towards the delivery chamber ( 20) and replaced In this way, the drive can be replaced relatively easily and without dismantling the drive, in particular the sealing sleeve 6

  (11) which constitutes a wearing part.

  In FIG. 1, it can be seen, by the representation in broken lines (13 ′) of the sealing membrane (13), that the radial width of this membrane, in its loose connection areas (29), which is between the cylinder (10) of the pump and the oscillating piston (2), is greater than that which corresponds to the geometrical distance separating

  the fixing zones (30) and (31) of the waterproofing membrane

  it 6 (13) on the pump cylinder (10) and the piston os-

  cillant (2) respectively As a consequence, the dimensions

  of the waterproofing membrane 6 it 6 (13) are not only suitable

  tees at the stroke (H) of the oscillating piston (2), but

  to some extent poses an "excess" of

  loose connection (29) on the waterproofing membrane (13).

  In this way, its stress is kept at a low value.

their.

  The pump (1) can be used for both

  liquid flow only for gas discharge If there is already a supply overpressure in the suction line (28) and that, consequently, there is already a

  slightly higher pressure in the intermediate chamber 6 di-

  area (25), it is advantageous if the oscillating piston (2) has

  sede a support flange (32) for the waterproofing membrane

ity (13) (Figure 2).

  The pump (1) can be fitted with a sealing sleeve

  sheaity (11), in which the wall thickness (S) of the re-

  annular lip region (33) which is pressed against the wall (9) of the cylinder (10) of the pump with a gasket has the same thickness as the portion (34) of the cuff which extends radially and which is tightened between the lower and upper clamping parts (18,19) of the piston part (3) A

  such a one-piece sealing sleeve (11) which pre-

  feels substantially the same wall thickness, is represented by 6

  shown in Figure 3 Figure 4 instead shows a

  embodiment of a sealing sleeve (11 a) 6 small

  In this case, the thickness (d) of the part

  tie (34) of the cuff which is oriented radially is greater than the thickness (b) of the lip region (33) In this way, the risk of undesirable bending of the radial part (34) of the cuff located in the region of the slot (Sp) between the wall (9) of the cylinder (10) of the pump: on the one hand, and the outer edge of the lower clamping piece (18), on the other hand, is reduced even

  when there is an overpressure in the chamber

  intermediate bre (25) and a discharge pressure of

  much higher in the discharge chamber (20)

  pit of the relatively thick embodiment of the radial portion (34) of the cuff, the lip region (33)

  which is thin, still applies to watertight seal

  che against the wall (9) of the cylinder (10) of the pump, like a self-sealing lip Figure 5 shows how we can reduce the width of the slot (Sp) that the part

  (34) of the cuff which is oriented radially, must

  check by the fact that the free diameter (D 3) of the cylinder (10) of the pump is produced in the central region (8) of the

  stroke (H) of the piston with a reduced diameter (D 3 ') compared to

  tively the maximum diameter (D 3) of the cylinder The inclination of the oscillating piston (2) and the length of the stroke (H) in Figure 5 are shown strongly exaggerated for the

clarity of representation.

  The above characteristics (thickening of the

  radial part (34) of the cuff and reduction of the window

  te by the diabolo shape of the cylinder (10) of the pump) as-

  not only increased durability of handling

  sealing seal (11), but also a reduction in

  risk of the oscillating piston causing damage

  tion of the pump cylinder after wear, in particular

  on the lip region (33) of the sealing sleeve (11).

  Thanks to the formation of an effectively tight seal on the sealing sleeve (11) and the long service life of this sleeve, the sealing membrane (13) is also less stressed 6 e and the pump (1) has a better

  efficiency In this measurement, we also obtain a com-

  advantageous combination of effects between the particular form

  for making the sealing lip 6 (11 a) and making it

  particular truction of the pump (1), fitted with its oscillating piston (2), its 6 anch 6 sleeve cuff (11) and its

6 waterproofing membrane (13).

  All the features described above and

  diqu 6 es in the claims should be considered 6 es

  as essential for the invention both in isolation and

in all combinations.

Claims (8)

- CLAIMS -   1 Pump whose piston is hermetically isolated from the   crankshaft chamber by a sliding seal   health which leans against the pump cylinder, characteristic   risée in that the pump (1) has an oscillating piston (2) which is provided with a sealing sleeve (11) in qualit 6 of sliding sealing packing, and in that a membrane   sealing (13) is provided between this sealing sleeve-   ity and the chamber (12) of the crankshaft.   2 Pump according to claim 1, characterized in that   that the sealing membrane (13) is fixed to the piss part   tone proper (3) or to another equivalent part of the piston oscillating by its central region and fixed to the crankshaft housing or to an equivalent part (10, 23) of the   pump by its outer edge (22).   3 Pump according to one of claims 1 and 2, charac-   characterized in that the intermediate chamber (25) located between the sealing sleeve (11) and the sealing membrane   (13) is connected to a drain pipe (24), preferably   at the suction line (28) of the pump (1).   4 Oscillating piston pump according to one of the claims   1 to 3, characterized in that the sealing sleeve   tee (11) and the waterproofing membrane (13) can or can be disassembled and replaced by acting through the pump discharge (1).   Pump according to one of claims 1 to 4, character-   in that the sealing membrane (13) is adapted to   the stroke (H) of the piston (2) of the pump, advantageously thanks to   this to an enlargement of the radial width of its area of loose connection (29).   6 Pump according to one of claims 1 to 5, character-   in that the oscillating piston (2) has an adhesive   support ridge (32) intended to give support to the diaphragm sealing (13).   7 Pump according to one of claims 1 to 6, character-   in that the sealing membrane (13) is mounted at   near the sealing sleeve (11).   8 Pump according to one of claims i to 7, compre-   having at least one sealing sleeve which comprises a sleeve portion extending approximately radially and which is partially held by the piston part proper, as well as a lip region which bears with a seal against the cylinder wall, characterized in that the wall thickness (d) of the portion (34) of the sleeve extending   Almost radially is greater than the thickness of pa-   king (b) of the lip region (33) of the sealing cuff tee (11).   9 Pump according to one of claims i to 8, charac-   terized in that the free width (diameter D 3) of the cylinder   dre (10) of the pump has a slightly reduced diameter (D 3 ')   duit with respect to the maximum diameter (D 3) of the cylinder in   the central region (35) of the stroke (H) of the piston,   a measure that adapts to the movement of the eye lation of the oscillating piston (2).