LU92959B1

LU92959B1 - Fluid flow limiter

Info

Publication number: LU92959B1
Application number: LU92959A
Authority: LU
Inventors: Philippe Schmitz; Stephan Sellen
Original assignee: Luxembourg Patent Co
Priority date: 2016-01-26
Filing date: 2016-01-26
Publication date: 2017-08-07
Also published as: WO2017129628A1

Abstract

The invention is directed to a flow limiter (2) for a fluid, comprising an element (14) movable along a longitudinal axis (10) of said element and with at least one fluid passage (20) extending through said element (14) parallel to the longitudinal axis (10), with an inlet (201) and an outlet (202); a flow limiting surface (24) configured for cooperating with a seat (26); and at least one flow constraining section (22) arranged in the at least one fluid passage (20) and configured for converting the flow into a biasing force for moving the flow limiting surface (24) towards the seat (26) in order to reduce and/or close the flow. The at least one flow constraining section (22) is located at the outlet(s) (202) of the at least one fluid passage (20) and is configured for radially deviating the flow from said passage(s) (20). (fig. 1) 92959

Description

FLUID FLOW LIMITER

Technical field [0001] The invention is directed to fluid flow limiters, in particular for compressed gas.

Background art [0002] Prior art patent document published US 2008/0006330 A1 discloses a throttle mechanism for water. The mechanism comprises a hollow main body, a movable sleeve received in the body, and a screw engaging the body for securing the sleeve in the body. The sleeve comprises a restricted hole forming the inlet of a passage for the fluid. The sleeve is held in a distant position from a seat in the body by means of a spring. The outlet of the passage is radial and formed between the seat and the front surface of the sleeve vis-à-vis of the seat. In that position of the sleeve, the fluid can flow through the inlet, the passage in the sleeve and the outlet. When the flow increases, the force exerted by the fluid on the sleeve at the inlet with the restricted passage moves the sleeve towards the bottom of the body so that the cross-section of the outlet between the seat and the front surface of the sleeve diminishes and thereby reduces the flow. This flow limiter is essentially designed for water, i.e. for liquids. Indeed, for applications with gases, the restricted hole would need to be of a smaller size. This would however result in an important pressure drop which is not desirable. In addition, the body of that flow limiter is of a complicated design that increases the production cost.

[0003] Prior art patent document published CN 102182850 A discloses also a flow limiter for water. It comprises essentially an outer sleeve and a movable element received in the sleeve and a threaded ring for securing the movable element in the outer sleeve. The movable element comprises a through passage for the water and a sidewall. It comprises also holes provided radially in the sidewall. It comprises also a conical external surface that is configured for cooperating with a seat surface of the outer sleeve. A spring holds the movable element in a position where the conical surface is distant from the seat surface. During operation, water can flow centrally through the movable element and laterally through the radial holes and the passage between the conical surface and the corresponding seat of the outer sleeve. When the flow increases, the somewhat restricted central passage in the movable element induces a force on the movable element that tends to move it in a downstream direction. Such a movement of the element has for effect to reduce the cross-section between the conical surface and the corresponding seat. A reduction of that cross-section has for effect to reduce the total flow, resulting in a flow limitation. That flow limiter does not however permit a total shut-off of the flow passage.

[0004] Prior art patent document published CN 103591317 A discloses also a flow limiter. It consists essentially of a movable closure head supported by a central rod that is slidably supported by a support. A spring urges the head distant from a seat. When fluid, like water, is flowing along the head and through the seat, the deviation of the fluid around the head generates a closing force on the head. This latter can therefore move towards the seat so as to reduce the cross-section of the fluid passage between the head and the seat, thereby reducing or even shutting-off the flow. This construction of flow limiter is however bulky in the axial direction due essentially to the presence of the spring on the opposite side of the movable head.

Summary of invention

Technical Problem [0005] The invention has for technical problem to provide a flow limiter that overcomes at least one of the drawbacks of the prior art, more particularly of the cited prior art. More particularly, the invention has for technical problem to provide a flow limiter that is compact, reliable, of a simple construction and producing minimal pressure drop.

Technical solution [0006] The invention is directed to a flow limiter for a fluid, comprising: an element movable along a longitudinal axis of said element and with at least one fluid passage extending through said element parallel to the longitudinal axis, with an inlet and an outlet; a flow limiting surface configured for cooperating with a seat; at least one flow constraining section arranged in the at least one fluid passage and configured for converting the flow into a biasing force for moving the flow limiting surface towards the seat in order to reduce and/or close the flow; wherein the at least one flow constraining section is located at the outlet(s) of the at least one fluid passage and is configured for radially deviating the flow from said passage(s).

[0007] According to a preferred embodiment, the flow limiting surface is located at an end of the movable element, downstream of the outlet(s) of the at least one fluid passage, so that the flow from said outlet(s) to said surface follows a curved pathway.

[0008] According to a preferred embodiment, the flow limiting surface is diskshaped and preferably generally perpendicular to the longitudinal axis of the movable element.

[0009] According to a preferred embodiment, the at least one flow constraining section comprises a flow deviation surface that extends perpendicularly to the longitudinal axis of the movable element, or extends radially with an angle of less of 30° with a perpendicular to the longitudinal axis of the movable element.

[0010] According to a preferred embodiment, the movable element is cylindershaped, preferably with a shoulder against which a spring slip over said element can abut.

[0011] According to a preferred embodiment, at least one flow constraining section comprises several sections distributed around the movable element.

[0012] According to a preferred embodiment, the at least one fluid passage comprises several passages extending parallel to the longitudinal axis, each of said passages intersecting one of the flow constraining sections.

[0013] According to a preferred embodiment, the movable element comprises a main portion with an external cylindrical guiding surface and an end portion with a reduced cross-section, said portion comprising a front face forming the flow limiting surface.

[0014] According to a preferred embodiment, the several fluid passages extend into the end portion with reduced cross-section of the movable element.

[0015] According to a preferred embodiment, the several fluid passages are formed by cylindrical holes intersecting partially the end portion with reduced cross-section and partially the main portion of the movable element, said intersections forming the outlets of the passages.

[0016] According to a preferred embodiment, the end portion with reduced cross-section is cylindrical with a diameter Di, and each of the several fluid passages extends at a distance x from the longitudinal axis of the element, where x<Di/2.

[0017] According to a preferred embodiment, the several fluid passages are formed by cylindrical holes of a diameter D2 and axially extending beyond the main portion into the end portion with reduced cross-section by a distance y, where y<Tr.D2/4.

[0018] According to a preferred embodiment, it further comprises a spring that can be slip over the movable element so as to abut against a shoulder of said element.

[0019] According to a preferred embodiment, it further comprises a screw of a diameter that is equal or larger to the diameter of the element, said screw providing a through hole so as to serve as securing screw for the movable element.

[0020] According to a preferred embodiment, it further comprises a body with a passage for the fluid, a seat around said passage and a bore in said passage, said bore slidingly receiving the movable element.

Advantages of the invention [0021] The invention is particularly interesting in that it provides a compact, simple and efficient design. The passage(s) can be drill holes in the body of the movable element. The movable element can then be guided by its external surface. The flow constraining portions located at the outlets of the passages in the movable element provide an interesting flow deviation effect that optimizes the resulting closing force for a given pressure drop. Said differently, this design reduces the pressure drop for a given flow where the limiter closes.

Brief description of the drawings [0022] Figure 1 is a cross-sectional view of a flow limiter according to the invention, the flow limiter being in an open position.

[0023] Figure 2 is a perspective view of the movable element of the flow limiter of figure 1.

[0024] Figure 3 is a cross-sectional view of the flow limiter of figure 1, the flow limiter being in a closed position.

Description of an embodiment [0025] Figures 1 to 3 illustrate an embodiment of the invention. Figures 1 and 3 are cross-sectional views of the flow limiter, figure 1 illustrating the limiter in an open state and figure 3 illustrating the limiter in a closed state. Figure 2 is a perspective view of the movable element of the flow limiter.

[0026] The flow limiter 2 comprises a body 4 with a passage for a fluid like compressed gas, the passage forming an inlet 6 and an outlet 8 of the flow limiter. The passage extends along a longitudinal axis 10 along which a bore 12 is machined. For instance the bore 12 comprises first and second portions 121 and 122, respectively, which house a movable element 14 of the flow limiter. The bore 12 comprises also third and fourth portions 123 and 124, respectively, which house a securing screw 16 holding the movable element 14 is the bore portions 121 and 122.

[0027] The securing screw 16 comprises a through-hole 161 allowing the fluid to flow from the inlet 6 to the movable element 14 and the outlet 8. It can also comprise a shoulder 162 resting on a corresponding shoulder portion between the third and fourth portions 123 and 124, respectively, of the bore 12. It can also comprise an external thread 163 engaging a female thread on the third bore portion 123. The through-hole 161 can be shaped with a hexagon profile allowing a rotational engagement of a tool, like an Allen key, for tightening the screw in its securing position.

[0028] The movable element 14 is slidably received in the bore portions 121 and 122. A compression helical spring encircles the movable element 14 and abuts against a shoulder of said element so as to exert a resilient force that biases the element against the securing screw 16, corresponding to an open position as illustrated in figure 1.

[0029] The movable element 14 comprises four passages 20 extending parallel to the longitudinal axis 10 of the bore 12 and of said element 14. For instance, these passages are cylindrical, i.e. straight and with a circular cross-section, and can be formed as drill-holes. As is apparent in both figures 1 and 2, the movable element 14 is generally cylindrical with a main portion 141 and an end portion 142 with a reduced diameter. The movable element 14 comprises also a shoulder 143 on which the spring 18 rests. The passages 20 are configured so as to intersect the outer surface of the end portion 142 with a reduced diameter. Each passage 20 comprises an inlet 201 on the inlet side of the element and an outlet 202 on the end portion 142.

[0030] With reference to figure 1, the movable element 14 comprises flow constraining sections 22 at the outlet 202 of the passages 20. These sections 22 force the flows in the passages 20 to change their direction from axial to radial towards the first bore portion 121. This deviation generates a force on the element 14 by application of the conservation of the linear momentum of the fluid. Each of the flow constraining sections comprises a flow deviation surface that extends perpendicularly to the longitudinal axis of the movable element. That surface can also extend radially with an angle of less of 30° with a perpendicular to the longitudinal axis of the movable element.

[0031] The movable element 14, more specifically its end portion 142 with a reduced diameter comprises an end face 24 forming a flow limiting surface that is configured for cooperating with the seat 26 around the outlet passage 8. In the open configuration that is illustrated in figure 1, the surface 24 is distant from the seat 26 and thereby allows the fluid to flow to the outlet passage 8.

[0032] In operation, when the fluid flows from the passage inlet 6 to the passage outlet 8, it flows through the passages 20 and is deviated at the bottom of said passages 20, in the flow constraining sections 22. This deviation produces a force on the element 14 that is oriented towards the seat 26. This force results from the principle of conservation of the fluid momentum. When the flow increases, the resulting force exerted by the fluid on the element 14 increases and moves it against the resilient force of the spring 18, thereby reducing the cross-section of the fluid passage between the surface 24 and the seat 26. The flow might then be limited and can then reach a level where the resulting force on the element is equilibrated with the resilient force of the spring 18. When the flow reaches an upper limit, the resulting force is great enough to compensate the resilient force of the spring and moves the element 14 towards the seat 26 until it contacts said seat. The flow is then shut-off and the fluid pressure is exerted against the element 14 over a cross-section that corresponds to the surface 24. The element 14 is then held in a closed position against the resilient force of the spring by the static pressure of the fluid. This situation is illustrated in figure 3.

[0033] With reference to figure 1, in order that the fluid flow generates a satisfactory force on the element in the flow constraining sections 22, it can be advantageous that the portion of flow in the passages 20 that collides with, and is deviated by, the end surface of the passages 20 is larger than the portion of said flow that can, at least in theory, pass by that surface. If x is the distance of the axis of the passages 20 to the longitudinal axis 10 and if Di is the diameter of the end portion 142, this advantageous geometry can be expressed as follows:

[0034] Still with reference to figure 1, the flow constraining sections 22 can not only deviate the fluid but also form a flow restriction. To that end, the cross-section of the passage outlets 202 can be less than the cross-section of the passages 20. This means that if D2 is the diameter of the passages 20 and y is the height of the passage outlets 2Ο2, the cross-section of said outlets can be approximated to a rectangle whose width is D2 and whose height is y. It results then which can be simplified as

[0035] The above approximation of the cross-section of said outlets to a rectangle whose width is D2 and whose height is y is particularly true when x=Di/2.

[0036] The material of the movable element and/or of the securing screw can be metal, like steel, stainless steel or brass.

[0037] The flow limiter that has been described can be integrated into the body of a valve, a flow regulator or any device that controls a flow of fluid. It can also be built as a standalone device to be fluidly connected to a fluid installation, e.g. comprising pipes, conduits, valve(s) and flow regulator(s).

Claims

A flow restrictor (2) for a fluid, comprising: a member (14) movable along a longitudinal axis (10) of said member and with - at least one fluid passage (20) extending through said element (14) parallel to the longitudinal axis (10), with an inlet (201) and an outlet (202); a flow restricting surface (24) configured to cooperate with a seat (26); at least one flow restriction section (22) disposed in the at least one fluid passage (20) and configured to convert the flow into a biasing force to move the at least one flow restricting surface ( 24) to the seat (26) to reduce and / or close the flow; characterized in that the at least one flow restriction section (22) is located at or at the outlets (202) of said at least one fluid passage (20) and is configured to radially deflect the flow from said said passage (s) (20).

Flow restrictor (2) according to claim 1, characterized in that the flow restricting surface (24) is located at one end of the movable element (14), downstream of the outlet (s) (202). ) of the at least one fluid passage (20), so that the flow of said at least one outlet (202) to said surface (24) follows a curved path.

Flow restrictor (2) according to any one of claims 1 and 2, characterized in that the at least one flow-limiting surface (24) is disk-shaped and preferably substantially perpendicular to the axis. longitudinal member (10) of the movable member (14).

Flow restrictor (2) according to one of Claims 1 to 3, characterized in that the at least one flow restricting section (22) comprises a flow deflecting surface which extends perpendicular to the longitudinal axis (10) of the movable member (14), or extends radially at an angle of less than 30 ° with a perpendicular to the longitudinal axis (10) of the movable member (14).

Flow limiter (2) according to one of Claims 1 to 4, characterized in that the movable element (14) is cylinder-shaped, preferably with a shoulder (143) against which a spring (18) ) threaded on said element (14) can abut.

Flow restrictor (2) according to claim 5, characterized in that the at least one flow restriction section (22) comprises a plurality of sections distributed around the movable element (14).

Flow limiter (2) according to any one of claims 1 to 6, characterized in that the at least one fluid passage comprises a plurality of passages (20) parallel to the longitudinal axis (10), each of said passages ( 20) intersecting one of the flow restricting sections (22).

The flow restrictor (2) according to claim 7, characterized in that the movable member (14) comprises a main portion (141) with a cylindrical outer guide surface and an end portion (142) with a section cross section, said portion (142) comprising a front face forming the flow restricting surface (24).

Flow restrictor (2) according to claim 8, characterized in that the plurality of fluid passages (20) extend into the reduced section end portion (142) of the movable member (14).

Flow restrictor (2) according to claim 8, characterized in that the plurality of fluid passages (20) are formed by cylindrical holes partially intersecting the reduced section end portion (142) and partially the main portion ( 141) of the element (14), said intersections forming the outlet orifices (202) of the passages.

Flow restrictor (2) according to one of Claims 8 to 10, characterized in that the reduced-section end portion (142) is cylindrical with a diameter Di and each of the plurality of fluid passages (20). ) extends at a distance x from the longitudinal axis (10) of the element (14), where x ^ Di / 2.

Flow restrictor (2) according to one of Claims 8 to 11, characterized in that the plurality of fluid passages (20) are formed by cylindrical holes of diameter D2 and extend axially beyond the main portion (141) of the member (14) in the reduced cross-section end portion (142) of said member (14) over a distance y, where y <TT.D2 / 4.

Flow restrictor (2) according to any one of claims 1 to 12, characterized in that it further comprises a spring (18) which can be threaded onto the movable member (14) so as to abut against a shoulder (143) of said element (14).

14. A flow restrictor (2) according to any one of claims 1 to 13, characterized in that it further comprises a screw (16) of a diameter which is equal to or greater than the diameter of the element. mobile (14), said screw (16) comprising a through hole (161) so as to serve as a fixing screw for the movable member (14).

Flow restrictor (2) according to any one of claims 1 to 14, characterized in that it further comprises a body (4) with a passage (6, 8) for the fluid, a seat ( 26) around said passage (8) and a bore (12) in said passage, said bore slidably receiving the movable member (14).