Flow control device

A flow control device having a first port, a second port, a third port and the movable member. In a first mode, the movable member seals the second port while allowing fluid flow between the first and third ports, wherein the differential pressure between the first port and third port, during the first mode, is about zero. In the second mode, the movable member seals the first port while allowing fluid flow between the third port and second port, wherein the movable member is adapted to transition from the first mode to the second mode in response to a small change in differential pressure.

BACKGROUND OF THE INVENTION

In pneumatic braking systems for heavy-duty trucks, air is vented from the pneumatic lines to release the service brakes. The lag time between the actual release of a brake pedal and the actual release of the vehicle brakes is referred to as brake release timing. Users desire brake release timing to be as small as possible. To enhance brake release timing, quick release valves are commonly employed. Quick release valves are typically installed in the air brake system at a point between the supply air volume and the delivery air volume. Upon release of the brake pedal, air that was delivered to the brakes is rapidly vented from the quick release valve instead of flowing all the way back to the air supply.

A known type of quick release valve is illustrated inFIG. 1. The valve10includes a housing12having a supply port14, an exhaust port16, and one or more delivery ports18. A flexible, disk-shaped diaphragm20resides in the housing12for sealing the supply port14or the exhaust port16when desired.

In operation, when the driver depresses the brake pedal, air flows into the supply port14causing the diaphragm20to seal against an exhaust seat22. At the same time, the air forces the outer edge of the diaphragm20downward, resulting in air flowing from the supply port14to the delivery ports18. When the driver releases the brake pedal, the air pressure at the supply port14is reduced. The air that had been delivered to the brakes flows back toward the supply port14. The differential pressure across the diaphragm20(i.e. higher pressure in the delivery port than the pressure in the supply port) moves the diaphragm20upward, away from the exhaust seat22, and into engagement with an inlet seat24. As a result, air from the delivery volume vents through the exhaust port16.

In some known quick release valves, a differential pressure occurs across the diaphragm when air flows from the supply port to the delivery ports. This is not desirable because it may result in an unbalanced pressure between the wheels of the vehicle. Furthermore, in some designs, the diaphragm will not establish a seal with the inlet port during brake release as rapidly as desired, especially during low-pressure applications, such as for example 30 psi or less. As a result, some delivered air may flow back into the supply port, thus degrading brake release timing.

SUMMARY

The present invention relates generally to a flow control device. In particular, the present invention relates to a flow control device that moves between a first mode and a second mode in response to a pressure differential across a movable member.

The flow control device may include a first port, a second port, a third port and the movable member. In a first mode, the movable member may seal the second port while allowing fluid flow between the first and third ports, wherein the differential pressure between the first port and third port, during the first mode, is about zero. In the second mode, the movable member may seal the first port while allowing fluid flow between the third port and second port, wherein the movable member is adapted to transition from the first mode to the second mode in response to a small change in differential pressure.

DETAILED DESCRIPTION

While various aspects and concepts of the invention are described and illustrated herein as embodied in combination in the exemplary embodiments, these various aspects and concepts may be realized in many alternative embodiments, either individually or in various combinations and sub-combinations thereof. Unless expressly excluded herein all such combinations and sub-combinations are intended to be within the scope of the present invention. Still further, while various alternative embodiments as to the various aspects and features of the invention, such as alternative materials, structures, configurations, methods, devices, software, hardware, control logic and so on may be described herein, such descriptions are not intended to be a complete or exhaustive list of available alternative embodiments, whether presently known or identified herein as conventional or standard or later developed. Those skilled in the art may readily adopt one or more of the aspects, concepts or features of the invention into additional embodiments within the scope of the present invention even if such embodiments are not expressly disclosed herein. Additionally, even though some features, concepts or aspects of the invention may be described herein as being a preferred arrangement or method, such description is not intended to suggest that such feature is required or necessary unless expressly so stated. Still further, exemplary or representative values and ranges may be included to assist in understanding the present invention however, such values and ranges are not to be construed in a limiting sense and are intended to be critical values or ranges only if so expressly stated.

This application discloses a flow control device having a plurality of ports and a flexible member that is movable in response to differential pressure across the member. In a first mode, the member is in a first position in which the member allows flow between a first and third port while sealing a second port. In a second mode, the member moves to a second position, in which the member seals the first port and allows flow between the second and third ports. The flow device is configured such that when the device is in the first mode, the pressure differential between the first and third ports may be zero. Furthermore, the flexible member is adapted to rapidly transition to the second position when, in the second mode, the pressure differential between the first port and third port is small, such as for example less than 30 psi.

FIG. 2illustrates an exemplary embodiment of the flow control device in accordance with the present invention. In the exemplary embodiment ofFIG. 2, the flow control device is realized as a quick release valve for use in a vehicle air brake system. One of ordinary skill in the art, however, will understand that the concepts disclosed herein are applicable to a variety of flow control devices, such as for example, a double check valve.

The flow control device30includes a housing assembly32having an inlet or supply port34, at least one delivery port36, an exhaust or outlet port38, and a chamber40that interconnects the ports. A movable member42, realized in the form of a diaphragm, resides within the chamber40for selectively sealing one or more ports. A wide variety of configurations for the housing32are possible. The particular configuration of the housing32inFIG. 2is presented for conveniently illustrating of the general arrangement of the ports and the movable member. Other arrangements, however, are possible. From a general perspective of flow control between ports, one of ordinary skill in the art will appreciate that the ports may be interchangeable. For example, the supply port may serve as an exhaust port or a delivery port, the delivery port may serve as a supply port or an exhaust port, and the exhaust port may serve as a supply port or a delivery port.

In the exemplary embodiment ofFIG. 2, the supply port34and the exhaust port38are substantially aligned along a central axis44, though that is not required. The supply port34and the exhaust port38may be formed as a portion of a supply insert46and an exhaust insert48, respectively. The supply port34and exhaust port38, however, may be formed integrally with the housing32or in some other suitable manner.

As shown inFIGS. 3A,3B, and4, the exhaust insert48of the exemplary embodiment ofFIG. 2has a first end portion50and a second end portion52. The exhaust insert48includes a side wall54having a generally cylindrical configuration centered along a central axis56. The side wall54includes generally cylindrical inner and outer side surfaces58,60. The inner side wall surface58defines a flow passage62, including an exhaust opening64at the first end portion50and exhaust port66at the second end portion52.

The inner side surface58includes a first and a second axially extending portion68,70, respectively, connected by a radially extending inner shoulder72. The first axially extending portion68extends from the exhaust opening64to the inner shoulder72. The first axially extending portion68may be configured to receive and engage with a push-to-connect fitting (not shown). The push-to-connect fitting, once inserted into the exhaust opening64, attaches to the inner side surface58. Thus, when the exhaust insert48is installed in the flow control device30, the exhaust insert48functions as a connection point with another flow control device, an air line, or other flow components. The exhaust opening64includes a chamfer74to make inserting the push-to-connect fitting easier.

Referring toFIG. 4, the second end portion52includes an exhaust seat76that circumscribes the exhaust port66. The exhaust seat76is adapted to form a sealing interface with the movable member42(seeFIG. 2) when the movable member engages the seat. The exhaust port66is configured to include a plurality of smaller openings78, which reduces the likelihood that the diaphragm42will extrude into the exhaust port66when the diaphragm and exhaust seat76are in sealing engagement.

The outer side surface60of the exhaust insert48includes a radially extending flange80adjacent the first end portion50. In addition, the outer surface60of the second end portion52has a generally tapered or conical configuration. As shown inFIG. 2, the flange80engages corresponding structure of the housing32when the exhaust insert48is installed to ensure that the exhaust seat76is properly positioned. The tapered second end portion52helps direct air flow from the inlet port34to the delivery ports36.

Referring toFIGS. 5A,5B, and6, the supply insert46has a generally cylindrical configuration with a first end82and a second end84. The second end84includes a plurality of generally round openings86evenly arranged around a central axis88. The openings86, however, may be shaped otherwise or arranged in a manner different than illustrated in the exemplary embodiment. Furthermore, though six openings86are shown inFIG. 5B, any number of openings two or greater is possible.

The openings86are in fluid communication with a central passage90that extends through the supply insert46to the supply port34at the second end84. A plurality of ribs92extend inward toward the central axis88. The ribs92are generally interspersed between the openings86and extend axially along the central passage90to the supply port34. A supply seat94circumscribes the supply port34.

FIGS. 7 and 8illustrate the diaphragm42of the exemplary embodiment ofFIG. 2. The diaphragm42has a generally cylindrical configuration and includes a body portion96and a radially-extending, flexible rim98. The body portion96is configured to extend into the central passage90. Thus, the diameter D1if the body portion96is slightly smaller that the diameter D2of the opening in the central passage90formed radially inward from the ribs92(seeFIG. 6). As a result, the ribs92keep the diaphragm42substantially centered along the axis88.

Referring toFIGS. 7 and 8, the flexible, radially extending rim98includes an inlet or supply side100, an outlet or exhaust side102, and an outer edge104that is feathered or thinner than a radially inner portion of the rim98. The feathered edge104extends radially toward the exhaust side102at an angle Φ. The angle Φ may be any angle 45 degrees or less. In one exemplary embodiment, the angle Φ is between 18 and 24 degrees. The thickness t of the flexible rim98is generally thinner than the thickness of flat diaphragms used in prior known quick release valves, such as for example, the diaphragm20in the valve10ofFIG. 1. The thickness of known flat diaphragms, such as the diaphragm20, is generally about 0.060″. The thickness t of rim98is less than 0.050″. In one embodiment, the thickness t is in the range of about 0.040″ to 0.050″, though thinner is possible. The feathering and thinness improves the overall flexibility of the rim98, or in other words, the rim98is generally more responsive to changes in air pressure than thicker, non-feathered, flat diaphragms.

Those skilled in the art will readily appreciate that the invention may be realized using a variety of materials For example, the diaphragm42may be made of or include a flexible portion made of a variety of elastomeric materials that exhibited sufficient flexibility to perform as described herein. Polymeric materials such as nitrile rubber and fluorocarbon polymers have proven sufficient. The housing assembly32, supply insert46, and the exhaust insert48, may be formed of a variety of materials, including but not limited to, plastic, aluminum, zinc, and steel.

Referring toFIG. 2, the supply insert46and the exhaust insert48are installed within the housing assembly32such that the inserts are substantially aligned along the central axis44, though that is not required. The inserts46,48may attach to the housing assembly32in a variety of ways, such as for example, by a threaded connection, adhesives, an interference fit, or other suitable method. The diaphragm42resides between the inserts46,48in a free floating manner with the body portion96of the diaphragm extending into the central passage90. The radial clearance c between the outer edge of the rim98and an inner surface106of the housing32is configured to be less than about 0.030″. In one embodiment, the clearance c in the range of about 0.015″ to 0.020″. In another embodiment, the clearance c is in the range of 0.005″ to 0.010.″ The tight clearance helps to restrict the amount of delivery air that flows back from the delivery volume into the supply port34, while at the same time providing some clearance for swell of the diaphragm42and dimensional tolerances.

In an installed configuration, the diaphragm42may move between a first position in which the exhaust side102of the rim98engages the exhaust seat76and to a second position in which the supply side100of the rim98engages the supply seat94. In the first position, the supply port34and the delivery ports36are in fluid communication, while the exhaust port38is substantially closed by the diaphragm42. In the second position, the delivery ports36and the exhaust port38are in fluid communication, while the supply port34is closed by the diaphragm42.

In the exemplary embodiment ofFIG. 2, the flow control device is configured as a quick release valve for a vehicle's air brake system. As such, a supply of pressurized air is connected in fluid communication with the supply port34. The delivery ports36are configured to route the pressurized air to the downstream brake components, such as for example, brake chambers. The exhaust port38is configured to vent air from the brake system to atmosphere.

In quick release valves which utilize a flat diaphragm, such as the known example shown inFIG. 1, air pressure on the diaphragm during the air apply mode may cause the flat diaphragm to extrude into the exhaust port. Diaphragm failures or blowouts have been known to result from this. The body portion96of the diaphragm42according to the present invention, however, provides sufficient support to the diaphragm to substantially eliminate the possibility of the diaphragm extruding into the exhaust port38. Thus, in general, the portion of the diaphragm42that seals against the exhaust seat76and covers the exhaust port38is thicker than that radially extending rim98. In one embodiment, the diameter D1of the body portion96is about as wide as the diameter of the exhaust seat76.

FIG. 2illustrates the flow control device in an air apply mode. The air apply mode occurs when a brake application is desired, such as for example, when the user depresses the brake pedal (not shown). Pressurized air enters the supply insert46and flows around the diaphragm body96to the supply port34. The plurality of openings86and radially extending ribs92help to guide or direct the air around the body96. The air pressure causes the exhaust side102of the diaphragm42to seal against an exhaust seat76. Because the diaphragm42is not constrained between the supply seat94and the exhaust seat76(i.e. it is free floating) and the flexible rim98does not contact the supply seat94when the diaphragm42engages the exhaust seat76, air can freely travel from the supply port34to the delivery port36. As a result there is no differential pressure between the supply port34and the delivery port36during the air apply mode. This reduces the possibly of an unbalanced pressure between the wheels of the vehicle.

FIG. 9illustrates the flow control device in an air release mode. When the user releases the brake pedal, air pressure in the supply port34is reduced. As a result, pressurized air that was delivered to the brakes flows back toward the supply port34. The flexible rim98, in response to the differential pressure between the delivery ports36and supply port34, flexes into engagement with the supply seat94. The rim98is more sensitive to changes in differential pressure than the diaphragms in known quick release valves, such as the valve10ofFIG. 1. Thus, even in a low pressure brake application, such as for example, below 30 psi, the rim98flexes and engages the inlet seat94. In one embodiment, the rim98will flex and engage the inlet seat94at a differential pressure from the delivery port36to the supply port34of around 20 psi. As a result, the amount of delivery air that flows back into the supply port is minimized, thus minimizing brake release timing.

At about the same time that the rim98is flexing toward the supply seat94, air pressure from the delivery port36moves the diaphragm42axially away from the exhaust seat76, thus opening the exhaust port38. As a result, air from the delivery volume vents through the exhaust port38.

The action of the diaphragm42as described in reference to the exemplary embodiment ofFIGS. 2-9is equally applicable to provide a double check valve function. As described above, the diaphragm, in response to air pressure changes, moves between a first and second position. In the first position, a first port and a second port are in fluid communication while the diaphragm blocks a third port. In a second position, the diaphragm blocks the first port while the second and third ports are in fluid communication. Thus, if the first and third ports are configured as inlet ports and the second port as a delivery port, then the flow control device containing this configuration would function as a double check valve, allowing flow into the delivery port from whichever inlet port has the higher pressure.