Reduction of noise in pneumatic valves

Abstract

A valve (1) according to the invention has: a first piston (2) which is designed to assume at least two positions (P1, P2), a sealing element (3) on which the first piston (2) is seated in a first position (P1); at least two connections (9, 10, 11) which are not fluidically connected to one another when the piston (2) is in the first position (P1), and which are fluidically connected to one another when the first piston (2) is in the second position (P2), wherein a flow deflection device (14) is provided in the flow path between the at least two connections (9, 10, 11). The flow deflection device (14) is used to reduce whistling noises when the valve is vented.

Description

[0001] DESCRIPTION

[0002] Reducing noise in pneumatic valves

[0003] The present invention is concerned with reducing noise in pneumatic valves.

[0004] In pneumatic valves, such as relay valves, a first piston can rest on a sealing element (closed position) and then be moved away from it (open position). There can also be a movable sealing element with two sealing seats operating in parallel, for example.

[0005] In the prior art, for example, document DE 38 27 350 A1 is known, which shows a pneumatic relay valve. This pneumatic relay valve has, in particular, a sealing chamber, and a throttle is provided in the outlet valve, which throttles the corresponding air flow.

[0006] When such a valve opens, noise can be generated by the air flow, for example, when used in pneumatic braking systems. Component tolerances and different opening cross-sections can also cause resonances that exceed the normal noise level many times over.

[0007] Such noises can occur, for example, in the form of a whistling or honking sound. Noise in pneumatic valves is particularly favored by the air flow in narrow gaps with high flow velocities and laminar flow directly behind them. In relay valves in braking systems, noise can occur particularly when valves are moved slowly. In particular, when a piston separates from its valve seat, a whistling sound can occur at the natural frequency of the air column in the piston.

[0008] Noises that occur in a valve during the venting of a brake system are often proportional to the released pressure. Therefore, it is an object of the present invention to provide a valve in which the noise development in the valve, and in particular whistling noises, is reduced.

[0009] This object is achieved by a valve according to claim 1.

[0010] Further advantageous embodiments of the present invention are the subject of the subclaims.

[0011] A valve according to the invention comprises: a first piston adapted to assume at least two positions; a sealing element on which the first piston rests in the first position; and at least two ports that are not fluidically connected to one another when the piston is in the first position, but are fluidically connected to one another when the first piston is in the second position. A flow deflection device is provided in the flow path between the two ports, i.e., in the valve gap.

[0012] Such a flow deflection device prevents laminar flows from occurring in the valve gap, which would otherwise sweep over a surface and cause corresponding noises, in particular whistling noises, due to friction.

[0013] The flow deflection device causes the laminar flow to become swirled, thus creating turbulence. This means that the flow no longer sweeps over surfaces in a laminar pattern and therefore no longer causes loud noises, especially whistling noises.

[0014] The flow deflection device preferably has a plurality of projections. This results in the turbulence of the laminar flow being even more pronounced. Preferably, at least four, preferably at least eight, projections are provided, and the projections form a circle in the flow path.

[0015] The flow deflection device is therefore preferably shaped like a crown with multiple prongs. This ensures that all areas of the laminar flow are covered by corresponding protrusions, and the flow deflection or turbulence is even more effective.

[0016] Preferably, the valve is designed as a pneumatic relay valve, and the first piston is designed as a control piston that is biased in one direction by a first spring element and movable in the opposite direction by pressure in a control chamber. The sealing element is annular, and the side of the piston facing away from the control chamber rests on the sealing element in the first position. A sealing element guide can be provided on the inside of the sealing element, more precisely in a recess in the inside, which guide points upwards over the sealing element in the direction of the first piston and preferably protrudes.

[0017] Preferably, the aforementioned projections are provided on the sealing element guide, more preferably in the area that projects beyond the sealing element toward the first piston. Thus, when the first piston is moved into an open position in which the valve can be vented, the flow runs inward in a ring shape beneath the first piston, with the vent connection provided within the recess of the sealing element or the sealing element guide. Therefore, the flow must always run over the projections; this disrupts the laminar flow and generates turbulence, which can reduce or prevent the whistling noise.

[0018] In another embodiment, the projections are arranged in the region on the sealing element that is radially inside the region in which the piston rests in the first position. In this embodiment, too, the flow is correspondingly swirled by the narrow region between the piston and the sealing element, which can prevent whistling noises. In a further embodiment, the projections are arranged on the underside of the first piston in a region that does not rest on the sealing element in the first position and extends below the sealing element in the first position. The projections of the piston are thus arranged in the recess of the sealing element.This ensures that if there is a gap between the piston and the sealing element, the flow always runs over the projections, which are designed to swirl the flow accordingly and reduce the whistling noise.

[0019] It should be noted that the piston is only moved into the open position so far that the flow in any case passes over the projections, ie is forced through the projections.

[0020] This resulted in a noise level between 5 and 15 dB lower than without the corresponding projections. In particular, this significantly reduced the whistling noise, and the corresponding energy of the whistling noise was thus significantly reduced.

[0021] Preferably, the projections are bevelled on a radially outer surface and thus have an upwardly tapered shape.

[0022] Particularly when the projections are provided on the sealing element guide, this design offers corresponding advantages during assembly, as the sealing element guide can be pushed more easily through the recess of the sealing element, which is then clamped annularly around the sealing element guide. The projections then essentially spread the sealing element open during assembly.

[0023] Preferably, the sealing element is arranged on a second piston, which is pushed upward by a second spring element. A valve seat is provided radially outside the piston, against which the sealing element can be preloaded. The second piston is movable by the movement of the first piston against the preload force of the second spring element. In such an embodiment, a valve with more functions can be provided, since multiple piston positions can be assumed.

[0024] Preferably, the sealing element guide is connected to a vent connection - the valve venting takes place through the sealing element guide, or more precisely through the inside of the sealing element guide.

[0025] In the following, advantageous embodiments of the present invention are described in more detail with reference to the accompanying drawings.

[0026] Fig. 1 shows a schematic sectional view of a valve according to a first embodiment of the present invention.

[0027] Fig. 2 shows a schematic sectional view of a valve according to a second embodiment of the present invention.

[0028] Fig. 3 shows a schematic sectional view of a valve according to a third embodiment of the present invention.

[0029] Fig. 4 shows a detailed view of a sealing element guide with corresponding projections according to a first embodiment of the present invention.

[0030] Fig. 5 shows a sealing element with corresponding projections according to a second embodiment of the present invention.

[0031] Fig. 6 shows a first piston with corresponding projections according to a third embodiment of the present invention.

[0032] Fig. 7 shows a sectional view of a valve according to a first embodiment of the present invention. Fig. 8 shows a sectional view of a valve according to a second embodiment of the present invention.

[0033] Fig. 9 shows a valve according to the invention according to a third embodiment of the present invention in sectional view.

[0034] Fig. 10 shows a detail view of Fig. 7 with the most relevant parts.

[0035] Fig. 11 shows a detail view of Fig. 8 with the most relevant parts.

[0036] Fig. 12 shows a detail view of Fig. 9 with the most relevant parts.

[0037] In Fig. 1 is a schematic sectional view of a valve 1 according to a first

[0038] Embodiment of the present invention is shown. The valve 1 is designed as a relay valve. Here, a first piston 2 is provided, which can be controlled accordingly by a pressure in a control chamber 4, which is connected to a control connection 8. Depending on how the pressure in the control chamber 4 is varied, the first piston 2 moves up or down. In the closed valve position, the first piston 2 sits on a sealing element 3. The sealing element 3 is annular. Within the sealing element 3, a sealing element guide 5 is provided, on which a plurality of projections 15 are provided. The projections 15 project upwards beyond the sealing element 3. Furthermore, the valve 1 has a first working connection 9 and a second working connection 10. At the end of the sealing element guide 5 that faces away from the projection 15, a corresponding vent connection 11 is provided.The first working port 9 opens into a first chamber 12, the second working port 10 opens into a second chamber 13. In a position of the first piston 2, as shown in Fig. 1, the first piston 2 sits on the sealing element 3, and thus the second working port 10 is not connected to the vent port 11. However, if the first piston 2 is moved slightly upwards, a narrow gap (valve gap) is created between the sealing element 3 and the lower end of the first piston 2. Air then moves through this gap from the second chamber 13 to the vent port 11. The air flow, which flows in a ring shape from the outside through the valve gap, must then pass through the projections 15 before it can flow on to the vent port 11.

[0039] Furthermore, the sealing element 3 is provided on a second piston 16. This second piston 16 is preloaded by a second spring element 7. If the first piston 2 is pushed further downward compared to the view in Fig. 1, the second piston 16 and the sealing element 3 seated thereon are displaced further downward, and thus the second piston 16 no longer rests on a valve seat 17 – the first working port 9 and the second working port 10, or the first chamber 12 and the second chamber 13, are thus connected.

[0040] Fig. 3 shows a similar representation to Fig. 1, but a second embodiment of the present invention. The functionality is similar to that in Fig. 1. However, it should be noted here that the projections 15 are not provided on the sealing element guide, but on the sealing element 3, although they are offset radially inward from the area in which the first piston 2 rests on the sealing element 3.

[0041] Fig. 3 shows a similar illustration to Fig. 1, but a third embodiment of the present invention. The valve 1 basically has the same components. It should be noted here that the projections 15 are not provided on the sealing element guide, but on the inside of the first piston 2, from where they extend downwards. However, the projections 15 are offset radially inwards so that they cannot sit on the sealing element 3. If the first piston 2 is moved upwards here, a narrow gap is created between the first piston 2 and the sealing element 3, through which air flows in, but the flow is correspondingly swirled by the projections 15 because the flow has to pass through these projections 15. This correspondingly swirls the flow and reduces the noise.

[0042] Fig. 4 shows a detailed view of the projections 15 on a sealing element guide 5 according to the first embodiment of the present invention. Here, it can be seen that the projections 15 are slightly beveled and taper upwards accordingly. Fig. 5 shows a detailed view of a sealing element 3 according to the second embodiment of the present invention; here, the projections 15 are provided in the area adjacent to a recess 4a of the sealing element. When the flow sweeps over the sealing element 3 from the outside to the inside and finally flows through the recess 4a, it must pass the projections 15 and is swirled by them.

[0043] Fig. 6 shows a detailed view of the first piston 2 according to the third embodiment of the present invention. Here, the projections are arranged inside the first piston 2, but not in the area where the first piston 2 could rest on the sealing element 3 (not shown here).

[0044] Fig. 7 shows a view of a valve 1 according to a first embodiment of the present invention. The main body 2 sits on a sealing element 3. The sealing element 3 is annular, and a sealing element guide 5 is provided inside the sealing element 3. The corresponding projections 15 are provided on the top of the sealing element guide 5.

[0045] Fig. 8 shows a view similar to Fig. 7, but according to the second embodiment of the present invention. The corresponding projections 15 are provided here on the sealing element 3.

[0046] Fig. 9 shows a third embodiment of the present invention, the projections are provided here accordingly on the first piston 2 on the lower side.

[0047] Fig. 10 shows a detail view of Fig. 7. Here it can be seen that the projections 15 are provided on the sealing element guide 5. These protrude upwards above the sealing element 3. In this illustration, the first piston 2 sits on the sealing element 3. Radially further out on the sealing element 3 there is also a valve seat 17 which serves to connect the first chamber and second chamber (not shown here). When the first piston 2 is moved upwards, air flows from the area outside under the lower end of the first piston 2 and passes the projections 15, and then the flow can progress through the sealing element guide 5, and thus pressure can be reduced accordingly.

[0048] Fig. 11 is a fragmentary view of Fig. 8 showing the second embodiment of the present invention. Here, the projections 15 are provided on the sealing element 3, which, however, is offset radially inward from the area where the first piston 2 rests on the sealing element 3. When air flows in from the outside, the air must pass through the projections 15 before flowing downward through the sealing element guide 5.

[0049] Fig. 12 shows a detailed view of Fig. 9. Here, it is shown that the projections 15 are provided at the lower end of the first piston 2—but offset radially inward from the area in which the first piston 2 rests on the sealing element 3. If flow flows radially inward from outside the first piston 2, the flow must also pass the projections 15, where the flow may be swirled, thereby preventing noise generation, particularly whistling noise.

[0050] The present invention is not limited to the embodiments shown above.

[0051] The projections can also have other shapes; a bevel is not necessarily required. For example, they can also be columnar, pyramidal, or trapezoidal.

[0052] LIST OF REFERENCE SYMBOLS

[0053] 1 valve

[0054] 2 first piston

[0055] 3 Sealing element

[0056] 4 control chamber

[0057] 5 Sealing element guide

[0058] 6 first spring element

[0059] 7 second spring element

[0060] 8 Control connection

[0061] 9 first working connection

[0062] 10 second working connection

[0063] 11 Vent connection

[0064] 12 first chamber

[0065] 13 Second Chamber

[0066] 14 Flow deflection device

[0067] 15 lead

[0068] 16 second piston

[0069] 17 Valve seat

Claims

PATENT CLAIMS 1. Valve (1 ), comprising: a first piston (2) which is adapted to assume at least two positions (P1 , P2), a sealing element (3) on which the first piston (2) sits in a first position (P1 ); at least two connections (9, 10, 11 ) which are not fluidically connected to one another when the first piston (2) is in the first position (P1 ) and which are fluidically connected to one another when the first piston (2) is in the second position (P2), wherein a flow deflection device (14) is provided in the flow path between the at least two connections (9, 10, 11 ).

2. Valve (1) according to claim 1, wherein the flow deflection device (14) has a plurality of projections (15).

3. Valve (1) according to claim 2, wherein at least 4, preferably at least 8 projections are provided, and the projections (15) are arranged in a circle in the flow path.

4. Valve (1) according to one of the preceding claims 2 or 3, wherein the valve (1) is designed as a pneumatic relay valve, wherein the first piston (2) is designed as a control piston which is prestressed in one direction by a first spring element (6) and is movable in the opposite direction by pressure in a control chamber (4); wherein the sealing element (3) is annular, and the side of the piston (2) facing away from the control chamber (4) sits on the sealing element (3) in the first position (P1).

5. Valve (1) according to claim 4, wherein a sealing element guide (5) is provided on the inside of the sealing element (4), which preferably projects upwards over the sealing element (3) in the direction of the first piston (2), and the Projections (15) are provided on the sealing element guide (5), more preferably in the region which projects upwards beyond the sealing element (3) in the direction of the first piston (2). Valve (1) according to claim 4, wherein the projections (15) are arranged in the region on the sealing element (3) which is located radially inside the region in which the piston (2) sits in the first position (P1). Valve (1) according to claim 4, wherein the projections (15) are arranged on the underside of the first piston (2) in a region which, in the first position (P1), does not sit on the sealing element (3) and are located in a recess (4a) of the sealing element, and extend below the sealing element (4) in the first position (P1). Valve (1) according to one of claims 2 to 7, wherein the projections (15) are bevelled on their radially outer surface so that they have an upwardly tapered shape.Valve (1) according to one of claims 4 to 8, wherein the sealing element (3) is arranged on a second piston (16) which is pressed against a valve seat (17) by a second spring element (7), wherein the valve seat (17) is provided radially outside the piston (2) and wherein the sealing element (3) can be prestressed against the valve seat (17), wherein the second piston (16) is movable by the movement of the first piston (2) against the prestressing force of the second spring element (7). Valve (1) according to one of claims 4 to 9, wherein the sealing element guide (5) is connected to a vent connection (11).

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