Systems and methods for retarding the speed of a railcar

Abstract

A system for retarding a railcar. The system includes a brake and an actuator that moves the brake between a closed position in which the brake slows the railcar and an open position in which the brake does not slow the railcar. The system further includes a hydraulic circuit through which a hydraulic fluid flows between the actuator, a pump, and a reservoir. A variable speed motor drives the pump to supply the hydraulic fluid from the reservoir to the actuator. The variable speed motor is operable at a plurality of speeds between fully-on and fully-off states. A control system determines a speed setting within the plurality of speeds for operating the variable speed motor based on a pressure of the hydraulic fluid in the hydraulic circuit, the speed setting being determined such that the pressure is sufficient for operating the actuator.

What is claimed is: 
     
         1 . A system for retarding a railcar, the system comprising:
 a brake;   an actuator that moves the brake between a closed position in which the brake slows the railcar and an open position in which the brake does not slow the railcar;   a hydraulic circuit through which a hydraulic fluid flows between the actuator, a pump, and a reservoir;   a variable speed motor that drives the pump to supply the hydraulic fluid from the reservoir to the actuator, the variable speed motor being operable at a plurality of speeds between fully-on and fully-off states; and   a control system that determines a speed setting within the plurality of speeds for operating the variable speed motor based on a pressure of the hydraulic fluid in the hydraulic circuit, the speed setting being determined such that the pressure is sufficient for operating the actuator.   
     
     
         2 . The system according to  claim 1 , further comprising a pressure sensor fluidly coupled within the hydraulic circuit and configured to measure the pressure of the hydraulic fluid therein. 
     
     
         3 . The system according to  claim 2 , wherein the control system compares the pressure of the hydraulic fluid in the hydraulic circuit to a table stored in memory for determining the speed setting for operating the motor. 
     
     
         4 . The system according to  claim 2 , wherein the control system compares the pressure of the hydraulic fluid to an upper setpoint for determining the speed setting, and wherein when the pressure of the hydraulic fluid is below the upper setpoint the control system is configured to determine the speed setting inversely proportionally to changes in the pressure of the hydraulic fluid. 
     
     
         5 . The system according to  claim 2 , wherein the control system compares the pressure of the hydraulic fluid to an upper setpoint for determining the speed setting, wherein the speed setting is greater when the pressure is below the upper setpoint than when the pressure is above the upper setpoint, and wherein the speed setting remains non-zero when the pressure is above the upper setpoint such that the hydraulic fluid continues to flow through the hydraulic circuit. 
     
     
         6 . The system according to  claim 1 , further comprising a fluid quality sensor operatively coupled within the hydraulic circuit and configured to compare a quality measurement of the hydraulic fluid as measured by the fluid quality sensor to a threshold, wherein the control system is configured to provide a notification when the quality measurement exceeds the threshold. 
     
     
         7 . The system according to  claim 6 , wherein the quality measurement comprises a type of particulate present within the hydraulic fluid, and wherein the notification is based at least in part on the type of particular present within the hydraulic fluid. 
     
     
         8 . The system according to  claim 7 , wherein the notification includes a recommended action based on the type of particular present to bring the quality measurement below the threshold. 
     
     
         9 . The system according to  claim 6 , wherein the control system permits a user to manually change the notification, and wherein the control system records when the notification is manually changed. 
     
     
         10 . The system according to  claim 1 , further comprising an accumulator fluidly coupled to the pump, wherein the pump charges the accumulator, and wherein the accumulator is configured to provide powered movement of the brake to the closed position when the pump is de-energized. 
     
     
         11 . The system according to  claim 1 , wherein the control system and the hydraulic circuit are configured to provide a non-powered movement of the brake from the closed position to the open position without the hydraulic fluid being forced from the actuator and without the hydraulic fluid being supplied to the actuator such that the actuator is in a relaxed position in which the hydraulic fluid from the actuator is given a free path back to the reservoir. 
     
     
         12 . The system according to  claim 1 , wherein the pump is configured to supply the hydraulic fluid to one end of the actuator to provide a powered movement of the brake to the closed position and to an opposite end of the actuator to provide a powered movement of the brake to the open position. 
     
     
         13 . The system according to  claim 1 , wherein the control system controls the speed setting of the variable speed motor by adjusting a frequency of voltage delivered thereto. 
     
     
         14 . The system according to  claim 1 , wherein the variable speed motor is a brushless AC induction motor. 
     
     
         15 . The system according to  claim 1 , wherein the control system is further configured to control the variable speed motor so as to not exceed at least one of a maximum current, maximum voltage, maximum speed, and maximum rate of speed change. 
     
     
         16 . A method for slowing a railcar, the method comprising:
 configuring a brake to slow the railcar when in a closed position and to not slow the railcar when in an open position;   configuring an actuator to move the brake into and between the closed position and the open position;   fluidly coupling the actuator, a reservoir, and a pump to form a hydraulic circuit, the pump being driven by a variable speed motor operable at a plurality of speeds between fully-on and fully-off states to supply hydraulic fluid from the reservoir to the actuator;   controlling the speed setting of the variable speed motor based on a pressure of the hydraulic fluid in the hydraulic circuit such that the pressure is sufficient to operate the actuator; and   operating the actuator to move the brake into the closed position to slow the railcar.   
     
     
         17 . The method according to  claim 16 , further comprising determining the pressure of the hydraulic fluid via a pressure sensor fluidly coupled within the hydraulic circuit. 
     
     
         18 . The method according to  claim 17 , wherein the pressure measured by the pressure sensor is distinct from a braking pressure applied by the brake. 
     
     
         19 . The method according to  claim 16 , further comprising fluidly coupling an accumulator within the hydraulic circuit such that the pump charges the accumulator and the accumulator is configured to provide a powered movement of the brake to the closed position when the pump is de-energized. 
     
     
         20 . A system for controlling a railcar moving along a set of rails, the system comprising:
 a member configured to selectively contact wheels of the railcar;   an actuator that moves the member between a closed position in which the member contacts the wheels of the railcar and an open position in which the member does not contact the wheels of the railcar;   a hydraulic circuit through which a hydraulic fluid flows between the actuator, a pump, and a reservoir;   a variable speed motor that drives the pump to supply the hydraulic fluid from the reservoir to the actuator, the variable speed motor being operable at a plurality of speeds between fully-on and fully-off states;   a pressure sensor configured to measure a pressure of the hydraulic fluid in the hydraulic circuit; and   a control system that determines a speed setting within the plurality of speeds for operating the variable speed motor based on the pressure of the hydraulic fluid in the hydraulic circuit, the speed setting being determined such that the pressure is sufficient for operating the actuator.