Digital multi-point electronic load weigh system

Details Digital multi-point electronic load weigh system Digital multi-point electronic load weigh system

2003-01-08

2004-11-23

Siconolfi, Robert A. (Department: 3683)

Fluid-pressure and analogous brake systems

Load control

Responsive to fluid pressure spring

C303S022100, C303S009690, C303S020000

Reexamination Certificate

active

06820944

ABSTRACT:

FIELD OF THE INVENTION
The invention generally relates to a system for controlling the brakes of a railcar. More particularly, the invention pertains to a brake control unit capable of being used with many different types of electropneumatic brake control systems for controlling the brakes on one or more trucks of a railcar. Still more particularly, the invention pertains to a device that electronically compensates for the weight of the load borne by a railcar truck in formulating the braking effort to be applied to the wheels of that truck.
BACKGROUND OF THE INVENTION
A typical passenger transit or subway type train includes a locomotive, a plurality of railcars and several trainlines. The trainlines include both pneumatic and electrical lines most of which run from the locomotive to the last railcar in the train. The main reservoir equalization (MRE) pipe is one such pneumatic trainline. It consists of a series of individual pipe lengths. Secured to the underside of each railcar, one such pipe length connects via a coupler to another such pipe length secured to a neighboring railcar. The MRE pipe is thus essentially one long continuous pipe that runs from the locomotive to the last railcar. Charged by air compressors, which may be located throughout the train, it is the MRE pipe that serves to supply air to the various reservoirs, such as the supply reservoir, located on each railcar in the train.
One pneumatic trainline of particular importance to passenger transit and subway type trains is the brake pipe. It is used to convey to each railcar in the train an emergency brake signal when an emergency condition arises. Of similar importance is the brake control trainline that is used to carry the brake command to each railcar in the train as discussed below. Contained within a protective conduit along with other electrical trainlines, the brake control trainline is similarly formed from individual conduits connected in series.
A locomotive for a passenger transit or a subway type train typically has an electropneumatic brake control system such as the RT-5 Brake Control System produced by the Westinghouse Air Brake Technology Company (WABTEC). Adapted or configured to fit the needs of various passenger transit authorities, each of the RT-5 style systems currently in service feature a master controller by which a train operator can direct the overall braking and propulsive efforts for the entire train.
The master controller in the locomotive houses a handle, a computer and various other related components. The handle can be moved longitudinally anywhere along its range of motion and into any one of several designated positions. By moving the handle into the appropriate position, a train operator can initiate, maintain or halt braking or propulsion of the train. For example, from a position in which the train is currently being propelled, moving the handle to what is referred to as the full service position causes a service application of the brakes. Similarly, when moved to the emergency position, the operator can initiate an even faster type of braking referred to as an emergency application of the brakes. There are other positions for the handle whose purposes are beyond the scope of the present invention described and claimed below.
Based on the positions of the handle, the computer of the master controller can ascertain whether, and to what degree, the overall braking or propulsive effort of the train should be reduced or increased. A keyboard may also be used to permit the operator greater access to the brake equipment, allowing, for example, input of set-up parameters. Other known components may also be used to provide various other signals to the computer.
Based on the inputs it receives and the software that dictates its operation, the master controller essentially controls the overall operation of the brakes. For service braking, the master controller formulates the brake command appropriate to current conditions and conveys it along the brake control trainline to each of the railcars in the train. Through its brake command, the master controller can order any action from a release of brakes to a service application of the brakes or any degree of brake application in between those two extremes.
For emergency braking, a push-button type emergency valve in the locomotive can be used to affect a drop in brake pipe pressure to an emergency level using both pneumatic and electrical means simultaneously. When push-actuated, the emergency valve provides a path for the brake pipe to vent directly to atmosphere. It also simultaneously deenergizes an emergency trainline thereby deenergizing one or more emergency magnet valves to further vent the brake pipe.
Alternatively, when directed by the master controller, an emergency brake control valve on the locomotive could be used to decrease brake pipe pressure to the emergency level. By reducing the brake pipe pressure to the emergency level, whether initiated from the locomotive or from any other point in the train, this sends an emergency brake signal along the brake pipe to all other railcars in the train.
On passenger transit and subway type trains, the brake pipe is typically operated according to a binary logic scheme. Normal operating pressure for the brake pipe during non-emergency situations ranges from 130 to 150 psi, the pressure to which it is charged via the MRE pipe. The transition point, or emergency level, lies at approximately 90 psi. A pressure of 90 psi or below indicates an emergency. It is this lower pressure range that constitutes the emergency brake signal.
Each passenger transit railcar typically includes an electronic controller and two trucks, with each truck typically having two axles. In response to the brake command received from the master controller in the locomotive, the electronic controller controls the operation of both trucks on the railcar. The electronic controller, however, has two central processing units (CPUs). Along with its associated interface equipment, each CPU controls the brake equipment of one truck independently of the other truck. It does so based on the brake command and various other inputs specific to the truck that it controls.
The brake equipment for a truck includes a pneumatic control unit and one or more pneumatically operated brake cylinders. Shown in
FIG. 1
, the pneumatic control unit typically houses an application magnet valve (AMV), a release magnet valve (RMV), a relay valve, an emergency transfer valve (ETV), a variable load valve (VLV) and an air spring pressure transducer. Used to convert the pressure received from a load sensing system on the truck, the air spring transducer provides a feedback signal indicative of the load borne by the truck.
The relay valve typically takes the form of a J-1 relay valve or similar type valve. It is an air piloted device whose construction and operation are well known in the brake control art. It features a control port connected to the ETV, a supply port supplied by the supply reservoir, an output port from which air can be directed from the supply reservoir to the brake cylinder(s), and an exhaust port from which to vent the brake cylinder(s) to atmosphere. The pressure of the air impinging upon its control port and the pressure of the air that the relay valve delivers to the brake cylinders will be approximately equal, though the air delivered by the latter will be in much greater quantity than that received by the former.
During non-emergency operation of the pneumatic control unit (i.e., when brake pipe pressure lies above the transition point), the ETV assumes an access state in which it connects the control port to both the AMV and RMV. The AMV when opened then allows air from the supply reservoir via the VLV to reach the control port. The RMV when opened allows whatever pressure that impinges on the control port to be vented to atmosphere.
By selectively controlling the opening and closing of the AMV and RMV when the ETV is switched to the access state, the electronic controller can control the magnitude of the pressure

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