Measuring and testing – Volume or rate of flow – Using differential pressure
Reexamination Certificate
1999-07-07
2003-09-16
Patel, Harshad (Department: 2855)
Measuring and testing
Volume or rate of flow
Using differential pressure
C073S861530
Reexamination Certificate
active
06619138
ABSTRACT:
FIELD OF THE INVENTION
The invention generally relates to flow adapter mechanisms of the type used to measure the rate at which air flows into the brake pipe of a locomotive. More particularly, the invention pertains to a dynamic flow adapter that is capable of dynamically varying the flow of air through the adapter according to the magnitude of the flow rate it is used to measure. Still more particularly, the dynamic flow adapter (i) employs for low to medium flow rates a primary orifice in a primary passage through which air flows to provide highly accurate measurements of flow rate and (ii) also opens for higher flow rates, to the extent determined by the magnitude of the flow rate, a dynamic flow valve disposed in a supplemental passage so as to assure that a sufficient quantity of air can be provided to the brake equipment of the train when the brake pipe must be quickly charged.
BACKGROUND OF THE INVENTION
The following background information is provided to assist the reader to understand the environment in which the invention will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless specifically stated otherwise in this document.
A freight train typically includes a plurality of locomotives, a plurality of railcars and a pneumatic trainline known as the brake pipe. A conventional freight train has its locomotives connected in series to form what is referred to as a locomotive consist. Alternatively, another type of freight train has its locomotives strategically positioned throughout the train so as to distribute more evenly the propulsive and braking power along its length. A train with its locomotives distributed in this way is said to operate in a mode of operation referred to as either distributed power operation or multiple unit service. The locomotives of a multiple unit freight train are equipped, collectively, with special equipment known as a Remote Multiple Unit (RMU) control system. Before discussing the specific aspects of conventional and multiple unit freight trains to which the invention relates, more elementary aspects of train operation are introduced to aid the reader in understanding the preferred use(s) to which the invention will be put.
The brake pipe is the means by which service and emergency brake commands are pneumatically conveyed from the brake control system in the lead locomotive to each of the vehicles in the train. The brake pipe is essentially one long continuous tube that runs from the lead locomotive to the last railcar. The brake pipe is actually composed of a series of interconnected pipe lengths, with one pipe length secured to the underside of each vehicle. The brake pipe is formed by connecting each pipe length via a coupler to another such pipe length on an adjacent vehicle.
It is to the brake pipe that the pneumatic brake equipment on each railcar interconnects via a branch pipe. The pneumatic brake equipment typically includes an auxiliary reservoir, an emergency reservoir, one or more brake cylinders and at least one brake control valve such as an ADB, ABDX or ABDW type valve made by the Westinghouse Air Brake Company (WABCO). Under conditions known in the brake control art, each brake control valve charges its two reservoirs with the pressurized air it receives from the brake pipe. It is the pressure level within the brake pipe that determines whether a brake control valve will indeed charge its reservoirs or deliver pressurized air previously stored in one or both of its reservoirs to the brake cylinders. When so pressurized, each brake cylinder converts the pressurized air its receives from its brake control valve to mechanical force. From the brake cylinders this force is transmitted by mechanical linkage to the brake shoes. The magnitude of the force applied to the wheels and/or disc brakes of the railcar is directly proportional to the pressure built up in the brake cylinders. Forced against the wheels and/or disc brakes, the brake shoes are used to slow and/or stop the rotation of the wheels. It is thus the pressure level in the brake pipe that determines whether and to what extent the railcar brakes will be applied.
In addition to the brake pipe, a locomotive has its own pneumatic trainlines including a main reservoir equalizing (MRE) pipe, an independent application and release (IAR) pipe, and an actuating pipe. Within a locomotive consist, the MRE, actuating and IAR pipes of each locomotive connect to the MRE, actuating and IAR pipes of the adjacent locomotives. The MRE pipe is used to equalize the pressure between the main reservoirs of each locomotive in the consist. Air stored in the main reservoir of a locomotive is used to charge the brake pipe to a normal operating pressure of approximately 90 psi when the brakes are released. It is the pressure within the IAR pipe that controls the delivery of pressurized air to, and thus the operation of, the brakes of the locomotive(s) in the freight train.
A locomotive has a brake control system such as any one of the various EPIC® Brake Equipment Systems produced by WABCO. An EPIC® brake control system generally includes a cab station unit, a keyboard, a display, a locomotive interface unit (LIU), a brake control computer and a pneumatic operating unit. The cab station unit generates various signals including those representing the positions of the automatic and independent brake handles, and through its cab control computer conveys commands corresponding thereto to the brake control computer. By moving the independent brake handle, the train engineer can order the brakes to be applied and released only on the locomotive(s). By moving the automatic brake handle, the train engineer can order the brakes to be applied and released not only on the locomotive(s) but also on all railcars in the train. The level to which the brake pipe pressure is reduced or increased, and thus the amount of braking power exerted by the brakes, corresponds to the position of the automatic brake handle.
The keyboard also permits access to the brake equipment, allowing, for example, the train engineer to select whether the locomotive will be set in the LEAD CUT-IN, LEAD CUT-OUT or TRAIL mode of operation. By viewing the display, the train engineer can monitor the operation of the brake equipment. The LIU connects power and certain electrical trainlines to the brake equipment and provides various known input and control signals to the brake control computer. Operating according to its programming code and the inputs it receives, the brake control computer governs the overall operation of the brakes. According to commands received from the brake control computer, it is the pneumatic operating unit that controls the pressures in the various reservoirs and in the pneumatic trainlines so as to control the brakes.
The pneumatic operating unit features a laminate to which the brake control computer and the various pneumatically and electropneumatically operated devices mount. The laminate contains numerous ports and internal passages. Through these ports and internal passages, the laminate interconnects these devices to each other and to branch pipes that carry air from or to the various storage tanks such as the equalizing reservoir and to the actuating pipe, the MRE pipe, the IAR pipe, the brake pipe, the brake cylinders and various other pipes on the train.
Among the various devices mounted to the laminate are an independent application and release (IAR) control portion, a brake cylinder (BC) control portion, and a brake pipe (BP) control portion. These control portions are primarily controlled by the brake control computer. The IAR control portion features pneumatic logic circuitry along with solenoid operated valves by which the pressure in both the actuating and IAR pipes can be controlled. The BC control portion also features pneumatic logic circuitry along with solenoid operated valves by which the pressure in the brake cylinders on the locomotive can be controlled. The BC control portion controls the pressure in the locomotive bra
Kettle, Jr. Paul J.
Klemanski Richard S.
James Ray & Associates
Patel Harshad
Westinghouse Air Brake Technologies Corporation
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