FR2490771A1 - RETAINING VALVE - Google Patents

Abstract

THE CHECK VALVE INCLUDES A PERFORATED AERODYNAMIC GUIDE BODY 45 AND A VALVE ELEMENT OR AN AERODYNAMIC VALVE BODY 35 LOCATED IN A CAGE 15. IN ITS OPEN POSITION THE VALVE BODY 35 RECEIVES INSIDE AT LEAST PART OF THE BODY OF GUIDANCE 45 ALLOWING FLUID TO FLOW AROUND THE VALVE ELEMENT AND GUIDE BODY. THE GUIDANCE BODY IS FIXED IN THE CAGE BY 40 SPACE SPACERS WHICH EXTEND RADIAL DIRECTION FROM THE GUIDANCE BODY AND ARE ALSO TANGENTIALLY ORIENTED IN RELATION TO IT TO BE ABLE TO ACCOMMODATE THE THERMAL LOAD. A SLEEVE 85 IS ATTACHED TO THE VALVE ELEMENT 35, THIS SLEEVE IS RECEIVED INSIDE A CYLINDER 70 ATTACHED TO THE GUIDE BODY 45. THE CYLINDER IS EQUIPPED WITH A PURGE OPENING 75.

Description

- 1 - The invention generally relates to check valves

  fluid and it relates more particularly to the check valves which are used in the air purge system of the compressor of a turbomachine.

  It is perfectly known in the state of the art

  purge of compressor discharge air from the compression section of a turbo-machine used as propulsion for a jet plane. Air is purged from the compressor to prevent engine pumping during start-up and acceleration, to heat the aircraft part and to heat the wings or other surfaces of the aircraft to prevent systems for purging compressor discharge air

  normally use check valves which

  prevent reverse current in systems which can occur, for example, when air purge systems from multiple motors communicate

  between them and if one of these motors is put out of service.

  Without the check valve preventing current reversal, such a condition could cause the flow of purged air from engines that are in operation to the engine that is out of service, which could interfere with the performance of the equipment. auxiliary heating mentioned above. The check valves used in these air purge systems must be capable of allowing air to pass under pressures of the order

  about 20 bar and having temperatures of approximately

  4300C. Check valves must also be able to close quickly under the conditions

of the current reversal.

  The known check valves used nor-

  improperly in the air purge systems of a compressor were normally of the valve type. However, these valve types have the characteristic of having a minimum bearing surface for the valve element in comparison with the flow surface of the valve. This lack of bearing surface militates against the durability of the valve, causing premature use of the valve seats at

  cause of flutter between valve and seats.

  -2- Examples for a known check valve used in an air purge system of a compressor can be found in United States patent 2,925,825. Although many other valves restraint or single track are known in the state of

  the technique, these valves often have flow paths

  They are slightly shrunk, tortuous or otherwise contribute to an undesirable decrease in the pressure of the fluid flowing through the valve. U.S. Patents 2,927,604 and 2,928,217 show other examples of known check valve construction. U.S. Patent 3,134,394 shows a check valve characterized by lower pressure drop than other check valves mentioned above, but. the check valve of the present invention constitutes a significant improvement over the valve of U.S. Patent 3,134,394 with respect to the characteristics of the pressure drop and the closing speed in the case of 'an inversion

current.

  The present invention provides an improved check valve having a non-tortuous flow path and providing minimal restriction to the current flowing through the valve. The pressure drop of the current passing through the valve is minimized and the valve closes quickly but in a controlled manner under the conditions of the current reversal. The valve element is supported by a large area bearing and the flapping of the valve element thus

  that wear due to the impact of flapping are minimized.

  The check valve of the present invention is provided with an aerodynamically shaped perforated guide body and an aerodynamically shaped valve member or cone arranged inside a cage so that under the conditions of the normal direction of current the valve member and the guide body form a central body mounted by spacers which easily accommodate the thermal load of the valve. The valve body and the valve cage define a passage

  flow with flow section essentially con-

  -3- constant along the valve. Fluid flowing in the normal direction through the valve opens the valve member, which in the open position is disposed around a front face of the guide body. In the case of a reversal of the current flowing through the valve, fluid can penetrate the perforated guide body and acts against a concave surface of the valve body which

  closes quickly under the influence of reverse current, inter-

  thus breaking the current through the valve. An assembly

  attenuation wiring to cylinder and. sleeve is located inside the guide body, the valve body being attached to the cylinder or sleeve so that a relative movement between these elements dampens the movement of the valve body, thereby minimizing oscillation and flapping unwanted from the valve body. The cylinder is purged to reduce the return constant of the cylinder and sleeve assembly to prevent piston rebounding when the valve opens. The bleed opening also reduces the magnitude of the vacuum formed in the cylinder which could oppose the closing of the valve. According to the preferred embodiment, the sleeve is received adjacent to the cylinder, the cylinder and the sleeve forming a large bearing surface accommodating the movement of the valve element of the check valve in order to

  to prevent an unwanted beat or other vibration.

  An embodiment of the invention will now be described with reference to the accompanying drawings, in which: FIG. 1 is a sectional view of the pressure relief valve

restraint of the present invention.

  Figure 2 is a side view of the valve.

  Figure 3 is a view from the other side of the valve

of restraint.

  The check valve of the present invention is designated as a whole by 10 and has a cage 15 having mounting flanges 20 and 25 at its opposite ends so that the valve can be attached to a pair of opposite pipes. Inside the cage there is provided an annular seat 30 with which the valve body or the valve element 35 comes into engagement when the valve closes - 4 - under the conditions of the current reversal (current

  flowing to the right side in Figure 1).

  A guide body 45 of aerodynamic shape which opposes a minimum restriction to the flow current in the normal direction is located in the cage 15 and supported by spacers 40. As best shown in Figure 2, the spacers are provided between the cage and the guide body and extend from the guide cczps radially outward and tangentially

  compared to this one. Such an orientation of the companies

  toises makes it possible to accommodate the thermal load as well as the load resulting from the pressure of the fluid by bending the spacers without overloading the points of attachment of the spacers to the cage and to the guide body. The guide body 45 has (with respect to the normal direction of the current) front and rear faces 50 and 55 connected at 58 in an appropriate manner, for example by welding, brazing or gluing, or by mechanical fixing means, such as rivets or the like. The front face 50 is perforated at 60 while the rear face 55 is perforated at 65, the perforations can easily accommodate fluid flowing in reverse direction through the valve to act on the valve element 35 in order to move it towards the valve seat (see the dashed lines in Figure 1). As shown, the perforations 65 are much smaller than the perforations 60, the perforations 60 and 65 being arranged essentially in the center of the front faces

  and back. These dimensions and this position of the per-

  holes are suitable for a check valve for use in an air bleed system of a compressor of a turbo-machine, but it is obvious that the check valve of the present invention is not limited to these dimensions and at this position of the perforations which depend on the type of fluid flowing through the valve as well as on the temperatures and the pressure of this fluid., The front and rear faces of the guide body are conical or of convergent shape and serve -5- means of attachment for the attenuation cylinder 70 dis-r placed inside the guide body essentially in the center thereof? The cylinder is provided with a purge opening 75 at its rear end and receives a sleeve 85,

  which is essentially contiguous inside the cylinder.

  The cylinder and the sleeve form a damping means or a damper to limit the impact force or the oscillation of the valve element. The bleed opening softens or reduces the return constant of the sleeve and cylinder assembly to prevent rebound of the valve member when the valve opens The bleed opening is also used to draw fluid into inside the cylinder when the valve member is moved to its closed position to militate against the formation of a vacuum inside the cylinder

  who could oppose the closing of the valve.

  The valve element 35 is conical or convergent in shape and is fixed to the end of the sleeve 85 by suitable means, such as for example a bolt 90 with nut 95. According to the preferred embodiment, the cylinder and the sleeve extend practically along the length

  complete with check valve. Because of this character-

  téristique these two elements provide extended bearing surfaces to support the movable valve element which

  limits beat or other vibrations

  valve element.

  The outermost part in the radial direction of the valve element 35 comes to rest tightly

  against seat 30 when the valve is closed (shown

  mixed line). As shown in Figure 1, the valve member 35 has a conical disc. Fluid flowing in the normal direction through the valve acts directly against the external surface or

  convex of the valve element to thereby open the

  pape by forcing the valve element backwards so that the front face of the guide body is partly received inside the valve element. The stream

  flowing in reverse direction is applied by the

  holes 65 and 60 of the guide body against the internal (concave) face of the valve element to move it against the seat 30 in order to close the valve. As best shown in Figure 1, the rear face 55 of the g corpsdage body and the valve element 35 essentially conical, form a central aerodynamic body located inside the valve. This central body and the interior of the cage 15 delimit a passage 100 of which

  the cross-section flow section is essential

  partially uniform between its ends. It is understood that this uniform flow section with the aerodynamic shape of the central body formed by the guide body and the valve member results in a minimum pressure drop through the check valve of the present

invention.

  As a result, the check valve of the present invention has the characteristic of a minimum pressure drop across the valve. Movement in opposite directions of the valve member between the open position and

  and the closed position is damped by the holding mechanism

  Sleeve and cylinder nuation which, due to its arrangement inside the valve, provides extended bearing surfaces for the movement of the valve body. The cylinder bleed opening militates against rebounding of the valve member and preventing it from closing by creating a vacuum inside the cylinder. By their arrangement inside the guide body, the bearing surfaces of the cylinder and of the sleeve are protected against contamination practically along their entire length. The perforations provided in the front and rear faces of the guide body 45 allow

  rapid closing of the valve in the event of a reversal

  current flow. Furthermore, such rapid closing of the valve is further improved by the concave construction of the disc of the valve member, which provides efficient capture of the fluid flowing in reverse. The check valve of the present invention has been shown without control or assistance means of

  all kinds, the operation of the valve being

  -7- controlled only by the direction of flow of the current passing through the valve, but it is obvious that springs, control means or other assistance means can be used if necessary. The invention has just been described above with reference to a preferred embodiment, but it is obvious to specialists that many modifications and variations can be made without departing from the scope of

the invention.

-8-

Claims (7)

CLAIM:   1. Check valve comprising a cage (15) deli-   providing an external wall with a flow passage for a fluid, a seat (30) arranged inside the cage, a valve element (35) located inside the cage and capable of being positioned by the stream of fluid flowing through the valve, this valve member, by applying the flow of fluid flowing in reverse, being held in contact with the seat to close the check valve and, by applying of the pressure of the fluid flowing in the normal direction, being released from the seat to open the check valve, and a perforated guide body (45) located inside the cage and forming with the valve element, under the conditions of the normal flow direction of the fluid, an internal wall of said passage, the perforations (60, 65) making it possible to accommodate the current flowing in reverse direction so as to be able to act against the valve element in order to place it in contact with the valve seat and thereby close the check valve , characterized in that the guide body is mounted inside the cage by several spacers (40) spaced from one another, each of these spacers being disposed between the cage and the guide body and s' extending thereof radially outward and in a tangential direction relative to this guide body.   2. Check valve comprising a cage (15) for-   mant an outer wall of a flow passage for a fluid, a seat (30) disposed inside the cage, a valve element (35) disposed inside the cage and can be positioned in that -this by the flow of fluid passing through the valve, the valve member, by   application of the pressure of the fluid flowing directly   tion, being kept in contact with the seat to close the check valve and, by applying the pressure of the fluid flowing in the normal direction, the valve element being released from the seat to open the   check valve, and a perforated valve body (45) comprising   carrying perforated and aerodynamic front and rear faces (50, 55), this guide body being disposed inside the cage and forming with the valve element under the conditions of the normal direction of flow of the fluid, a internal wall of said flow passage, the perforations (50, 65) accommodating the reverse current for the application of the latter against the valve element in order to move this valve element in contact with its seat to close the valve. restraint, characterized in that the valve element (35) has a conical disc, the current of the fluid flowing in the normal direction through the valve acting against the external face of this valve element to release it from the seat so that the front face (50) of the guide body is received at least partially inside the valve element. 3. Check valve according to claim 1 or 2, characterized in that the valve element (35) and the guide body (45) form an aerodynamic central body   having parts of front and rear surfaces essential- slightly conical.   4. Check valve according to claim 1 or 2, characterized in that the flow passage delimited by the cage (15), the guide body (45) and the valve element (35) has along any its length a section   essentially uniform flow.   5. Check valve according to claim 1 or 2,   characterized by a sleeve (85) fixed to the support element   pope (35) or to the guide body (45) and by a cylinder (70) receiving the sleeve inside, the cylinder being fixed to the guide body (45) or to the valve element (45), the sleeve and the cylinder forming a means   to dampen the oscillations of the valve element.   6. Check valve according to claim 5, characterized in that the cylinder (70) has a bleed opening (75) to limit the pressure of the fluid   enclosed in the cylinder to prevent kickback   valve element when the sleeve moves toward the bleed opening and to allow fluid to enter the cylinder when the sleeve moves away from the opening purge. - 10 -   7. Check valve according to claim 5, characterized in that the sleeve (85) is contiguous inside the cylinder (70), this cylinder and the sleeve forming bearing surfaces by which the valve element ( 35) is supported during its movement by report to headquarters (30).