WO2016024996A1 - Brake cylinder limiting valve - Google Patents
Brake cylinder limiting valve Download PDFInfo
- Publication number
- WO2016024996A1 WO2016024996A1 PCT/US2014/051285 US2014051285W WO2016024996A1 WO 2016024996 A1 WO2016024996 A1 WO 2016024996A1 US 2014051285 W US2014051285 W US 2014051285W WO 2016024996 A1 WO2016024996 A1 WO 2016024996A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- brake cylinder
- valve
- pressure
- brake
- cylinder pressure
- Prior art date
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T15/00—Construction arrangement, or operation of valves incorporated in power brake systems and not covered by groups B60T11/00 or B60T13/00
- B60T15/02—Application and release valves
- B60T15/36—Other control devices or valves characterised by definite functions
- B60T15/54—Other control devices or valves characterised by definite functions for controlling exhaust from triple valve or from brake cylinder
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T17/00—Component parts, details, or accessories of power brake systems not covered by groups B60T8/00, B60T13/00 or B60T15/00, or presenting other characteristic features
- B60T17/18—Safety devices; Monitoring
- B60T17/22—Devices for monitoring or checking brake systems; Signal devices
- B60T17/228—Devices for monitoring or checking brake systems; Signal devices for railway vehicles
Definitions
- the present invention relates to rail or freight car brake systems and, more particularly, to a brake cylinder limiting valves for an AAR-type freight car brake that prevents over-pressurization of the brake cylinder.
- Control valves used in freight car brake systems such as the DB-60 control valve manufactured by New York Air Brake Corporation of Watertown, New York, or the AB-type control valves manufactured by Wabtec Corporation of Wilmerding, Pennsylvania, typically supply air pressure to the brake cylinder of a freight car. If the brake cylinder or the plumbing between the control valve and the car has a leak, however, the brake cylinder will not maintain the original set pressure. In addition to brake cylinder leakage, resulting in low brake cylinder pressure, the brake system can leak into the brake cylinder, resulting in high brake cylinder pressure.
- Brake control systems on rail or freight cars that comply with AAR standards are referred to as displacement type system and the brake cylinder pressure is proportional to the size of the auxiliary reservoir and brake cylinder volumes, which are proscribed by AAR regulations and controlled by means of the brake control valve.
- Control of the brake cylinder pressure is in response to modulation of the brake pipe pressure by the train driver.
- these systems are very reliable, they operate in an open loop mode with the brake cylinder pressure being the result of the relationship between auxiliary reservoir and brake pipe pressures.
- a brake failure that results in over-pressurization of the brakes on a car in train is very hazardous and may result in "hot wheels,” which damages the wheels and raises the potential for a subsequent wheel failure and even train derailment.
- the train driver is usually unaware that a car has over-pressurized brakes due, in part, to the length of the train and the number of cars in the train.
- the present invention comprises a brake cylinder limiting valve having a first portion that determined actual brake cylinder pressure and a second portion that determined intended brake cylinder pressure, and then allows for venting of the brake cylinder pressure if the actual brake cylinder pressure exceeds intended brake pipe pressure by a predetermined threshold.
- the intended brake pipe pressure is determined based on a reduction in brake pipe pressure relative to emergency reservoir pressure and the preferred threshold for venting is a brake cylinder pressure that is more than two and one-half times the brake pipe pressure reduction, plus a nominal amount for tolerance.
- the first portion comprises a first chamber in communication with a source of brake cylinder pressure, a second chamber in communication with atmospheric pressure, and a first diaphragm separating the first and second chambers and having a first wetted area, with the diaphragm configured to open a brake cylinder pressure exhaust port against the bias of a spring.
- the second portion comprises a third chamber in communication with a source of brake pressure, a fourth chamber in communication with a source of emergency reservoir pressure, and a second diaphragm separating the third and fourth chambers and having a second wetted area that is greater than the first wetted area by a threshold ratio, where the diaphragm is moveable to impart a second force via a floating pin that also biases the seat into the closed position.
- the brake cylinder pressure in the first chamber will be exhausted when it overcomes the bias force of the spring and any bias force being applied by the second diaphragm.
- the wetted area ratio of the second diaphragm to the first diaphragm is preferably 2.5 to 1, thereby providing for the same ratio of brake pipe pressure reduction to brake cylinder pressure increase required in an AAR compliant braking system.
- the brake cylinder limiting valve may be interconnected to the existing 4-port testing interface of a pipe bracket, or integrated into any number of locations in a conventional brake control valve.
- FIG. 1 is a schematic of a brake cylinder limiting valve according to the present invention
- FIG. 2 is a perspective view of an AAR control valve retrofitted in a first configuration with a brake cylinder limiting valve according to the present invention
- FIG. 3 is a perspective view of an AAR control valve retrofitted in a second configuration with a brake cylinder limiting valve according to the present invention
- FIG. 4 is a perspective view of a brake cylinder limiting valve adaptor according to the present invention for interconnecting to an AAR control valve;
- FIG. 5 is a schematic of a brake control valve showing three alternative locations for the installation of a brake cylinder limiting valve according to the present invention.
- Valve 10 for preventing over- pressurization of a brake cylinder.
- Valve 10 is a 2.5: 1 differential pressure limiting valve which has a first portion that pneumatically determines the intended brake cylinder pressure and a second portion that compares the intended brake cylinder pressure to the actual brake cylinder pressure.
- the 2.5: 1 differential pressure is selected to account for the ratio of brake pipe pressure to brake cylinder pressure required to be in an AAR compliance system.
- a reduction in the brake pipe pressure will cause an increase in brake cylinder pressure which is 2.5 times the brake pipe reduction.
- the brake cylinder pressure is increased by 25 psi.
- valve 10 comprises a first port 12 in fluid communication with a source of brake cylinder pressure BC, a second port 14 in fluid communication with an exhaust EX (atmospheric pressure), a third port 16 in fluid communication with a source of brake pipe pressure BP, and a fourth port 18 in communication with a source of emergency reservoir pressure ER.
- Valve 10 further comprises a first diaphragm 20 separating a first chamber 22 that is in communication with first port 12 from a second chamber 24 that is in communication with second port 14 and exhaust EX.
- a spring 26 biases diaphragm 20 to move a seat 28 positioned thereon to selectively opens and close communication between first port 12 and an exhaust port 30.
- Spring 26 is configured to provide the equivalent biasing force of between 5 and 10 psi.
- a second diaphragm 32 is positioned in valve 10 to separate a third chamber 34 in communication with third port 16 and brake pipe pressure BP from a fourth chamber 36 in communication with fourth port 18 and emergency reservoir pressure ER. Movement of second diaphragm 32 is communicated to first diaphragm 20 via a floating pin 38, thereby allowing a decrease in brake pipe pressure BP to adjust the amount of force necessary to open seat 28.
- the wetted area of second diaphragm 32 separating the emergency reservoir pressure ER chamber 36 and brake pipe pressure BP chamber 34 is selected to be about 2.5 times the wetted area of first diaphragm 22.
- valve 10 will not open seat 28 and vent brake cylinder pressure BC to exhaust port 30 unless brake cylinder pressure BC in chamber 22 exceeds both the bias force of spring 26 and 2.5 times any force applied to diaphragm 20 by pin 38 and diaphragm 32, which is the amount of reduction of brake pipe pressure BP in chamber 34.
- the first portion of valve 10 comprises an actual brake cylinder pressure feedback that is compared against the intended brake pipe pressure as determined by brake pipe pressure.
- valve 10 can determine whether the actual brake cylinder pressure exceeds the intended brake cylinder pressure and exhaust the brake cylinder if it is over pressurized by an amount equal to the bias force of spring 26.
- Exhaust port 30 is preferably connected to the inlet 40 of an exhaust valve 42 having a pilot 44 in communication with brake cylinder pressure BC that acts against a valve spring 46 to selectively connected exhaust port 30 with an exhaust EX.
- Valve spring 46 is configured to provide a biasing force equal to about 20 psi and thus will close exhaust valve 42 if brake cylinder pressure BC falls below about 20 psi.
- Conventional AAR brake systems include a retainer valve that, when manually activated, will bottle up the brake cylinder pressure by sealing the brake cylinder exhaust. This allows the train driver to bottle up the brakes on the cars, and then make a release and recharge of the brake pipe and all of the control valves on the train while the retainer bottles brake cylinder pressure. Retainers are typically used while descending long grades. By AAR standard, the retainer will bottle 20 psi in the high pressure setting. Exhaust cut-off valve 42 thus disables the brake cylinder limiting valve in retainer operations to comply with AAR standards.
- both the emergency and auxiliary reservoirs are pressurized to the brake pipe pressure, usually 90 psi.
- the emergency reservoir pressure is unchanged from the original charge state.
- the brake cylinder limiting valve thus uses the difference between the emergency reservoir pressure and the brake pipe pressure to determine the brake pipe reduction, which is the brake command signal. The brake reduction is thus compared to the actual brake cylinder feedback pressure.
- valve spring 26 has a nominal preload of between about 5 and 10 psi. This preload prevents undesired leakage from the brake cylinder limiting valve 10 in the balanced state, and accommodates tolerance variations of the brake system. If brake cylinder pressure BC increases as a result of any undesired leakage into the brake cylinder, such as from the brake pipe, the auxiliary reservoir, or the emergency reservoir, and does so in an amount equal to or greater than the value of spring 26, first diaphragm 20 will move downwardly, as seen in Fig. 1, thereby opening seat 28 and allowing brake cylinder pressure in chamber 22 to escape out of exhaust port 30.
- FIG. 1 shows a brake cylinder limiting valve 10 having flexible diaphragms
- brake cylinder limiting valve 10 could be implemented using other comparable valve structures, such as a combination of pistons and seals that provide the requisite 2.5 to 1 area ratio between the actual brake cylinder feedback portion and the intended brake cylinder pressure determining portion.
- valve 10 may be provided in a module 50 adapted for interconnection to a single-sided pipe bracket 52 via the existing 4-port interface 54 that is provided for periodic connection to a single car testing device.
- 4-port interface 54 includes conduits that provide for fluid communication to brake pipe pressure BP, auxiliary reservoir pressure AR, emergency reservoir pressure ER, and brake cylinder pressure BC and can thus provide all needed inputs for valve 10.
- module 50 is connected directly to 4-port interface 54 of pipe bracket 52.
- module 53 would have to be removed so that a single car testing device could be connected to 4-port interface 54 for periodic testing of the braking system.
- valve 10 may be incorporated into an module 60 that is attached directly along a first side 66 to 4-port interface 54 and that contains a series of conduits 62 formed therein to provide fluid communication to valve 10 as well as to a corresponding set of ports 64 on a second side 68 that allow a conventional testing device to be attached to module 60 for periodic testing purposes.
- module 60 is shown in Fig. 3 to be attached to 4-port interface 54 with valve 10 above pipe bracket, module 60 could be configured to position valve 10 below pipe bracket 52.
- a test adaptor 70 may be bolted over adaptor 60 to allow for connection to a single car testing device.
- valve 10 may be configured into any portion of a braking system control valve, such as by redesigning the packaging of the control valve, as a module that interfaces to the release valve interface, or as a module fitted between either the service portion and the pipe bracket or the emergency portion and the pipe bracket (or by including valve 10 in any other location that has pneumatic access to brake pipe, emergency reservoir, and brake cylinder pressures).
- valve 10 may be integrated into one of at least three different locations, Alt 1, Alt 2, and Alt 3, respectively, of a control valve 72.
Abstract
Description
Claims
Priority Applications (5)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/US2014/051285 WO2016024996A1 (en) | 2014-08-15 | 2014-08-15 | Brake cylinder limiting valve |
BR112017002552-3A BR112017002552B1 (en) | 2014-08-15 | 2014-08-15 | BRAKE CYLINDER LIMITING VALVE |
CA2957162A CA2957162C (en) | 2014-08-15 | 2014-08-15 | Brake cylinder limiting valve |
CN201480081238.XA CN106573613B (en) | 2014-08-15 | 2014-08-15 | Checking cylinder limit valve |
AU2014403356A AU2014403356B2 (en) | 2014-08-15 | 2014-08-15 | Brake cylinder limiting valve |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/US2014/051285 WO2016024996A1 (en) | 2014-08-15 | 2014-08-15 | Brake cylinder limiting valve |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2016024996A1 true WO2016024996A1 (en) | 2016-02-18 |
Family
ID=51398968
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2014/051285 WO2016024996A1 (en) | 2014-08-15 | 2014-08-15 | Brake cylinder limiting valve |
Country Status (5)
Country | Link |
---|---|
CN (1) | CN106573613B (en) |
AU (1) | AU2014403356B2 (en) |
BR (1) | BR112017002552B1 (en) |
CA (1) | CA2957162C (en) |
WO (1) | WO2016024996A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2017155934A1 (en) * | 2016-03-07 | 2017-09-14 | Westinghouse Air Brake Technologies Corporation | Brake cylinder maintaining valve |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20020038976A1 (en) * | 2000-06-28 | 2002-04-04 | Hart James E. | Apparatus and method for pneumatically controlled graduated brake pressure release for freight train brake system |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6375277B1 (en) * | 2001-05-04 | 2002-04-23 | Westinghouse Air Brake Technologies Corporation | Manual release valve apparatus for ECP brake equipment |
JP5656729B2 (en) * | 2011-04-21 | 2015-01-21 | カヤバ工業株式会社 | Caliper brake device for vehicle |
US9333959B2 (en) * | 2012-04-03 | 2016-05-10 | Wabtec Holding Corp. | Brake cylinder maintaining valve |
-
2014
- 2014-08-15 AU AU2014403356A patent/AU2014403356B2/en active Active
- 2014-08-15 CN CN201480081238.XA patent/CN106573613B/en not_active Expired - Fee Related
- 2014-08-15 WO PCT/US2014/051285 patent/WO2016024996A1/en active Application Filing
- 2014-08-15 CA CA2957162A patent/CA2957162C/en active Active
- 2014-08-15 BR BR112017002552-3A patent/BR112017002552B1/en active IP Right Grant
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20020038976A1 (en) * | 2000-06-28 | 2002-04-04 | Hart James E. | Apparatus and method for pneumatically controlled graduated brake pressure release for freight train brake system |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2017155934A1 (en) * | 2016-03-07 | 2017-09-14 | Westinghouse Air Brake Technologies Corporation | Brake cylinder maintaining valve |
US10946850B2 (en) | 2016-03-07 | 2021-03-16 | Westinghouse Air Brake Technologies Corporation | Brake cylinder maintaining valve |
Also Published As
Publication number | Publication date |
---|---|
CN106573613B (en) | 2019-05-03 |
BR112017002552B1 (en) | 2022-07-19 |
CN106573613A (en) | 2017-04-19 |
BR112017002552A2 (en) | 2017-12-05 |
AU2014403356B2 (en) | 2018-08-09 |
AU2014403356A1 (en) | 2017-02-23 |
CA2957162C (en) | 2019-01-08 |
CA2957162A1 (en) | 2016-02-18 |
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