Systems and methods for retarding the speed of a railcar
A system for retarding a railcar having wheels. The system includes a brake and an actuator that moves the brake between a closed position in which the brake contacts the wheels of the railcar and an open position in which the brake does not contact the wheels of the railcar. The system further includes a hydraulic circuit through which a hydraulic fluid flows between the actuator and a reservoir. A first pump is operably connected within the hydraulic circuit and configured to provide the hydraulic fluid to the actuator for operating the brake. A heat exchanger is operably connected within the hydraulic circuit and configured to cool the hydraulic fluid flowing therethrough. A second pump is operably connected within the hydraulic circuit and configured to provide the hydraulic fluid to the heat exchanger. The heat exchanger prevents the hydraulic fluid within the hydraulic fluid from exceeding a target operating temperature.
1 . A system for retarding a railcar having wheels, the system comprising:
a brake and an actuator configured to move the brake between a closed position in which the brake contacts the wheels of the railcar and an open position in which the brake does not contact the wheels of the railcar;
a hydraulic circuit through which a hydraulic fluid flows between the actuator and a reservoir;
a first pump operably connected within the hydraulic circuit and configured to provide the hydraulic fluid to the actuator for operating the brake;
a heat exchanger operably connected within the hydraulic circuit and configured to cool the hydraulic fluid flowing therethrough, wherein the heat exchanger prevents the hydraulic fluid within the hydraulic circuit from exceeding a target operating temperature;
a second pump operably connected within the hydraulic circuit and configured to provide the hydraulic fluid to the heat exchanger;
a motor that operates at least one of the first pump and the second pump, wherein the motor is a variable speed motor operable at a plurality of speeds between fully-on and fully-off states; and
a control system configured to control a displacement of the first pump during operation thereof, wherein the displacement is controllable independently from controlling the variable speed motor.
2 . The system according to claim 1 , wherein the motor is liquid cooled.
3 . The system according to claim 1 , wherein the motor operates the first pump and the second pump simultaneously.
4 . The system according to claim 1 , wherein the motor is controlled via a motor drive, and wherein the motor drive is liquid cooled.
5 . The system according to claim 1 , wherein the variable speed motor is a brushless DC motor.
6 . The system according to claim 1 , wherein the variable speed motor is operable at the plurality of speeds by adjusting a frequency of voltage delivered thereto.
7 . The system according to claim 1 , further comprising a temperature sensor that measure a temperature of the hydraulic fluid within the hydraulic circuit, a valve operatively coupled within the hydraulic circuit and configured to change a flow of the hydraulic circuit to the heat exchanger, wherein the control system is operatively coupled to the valve and configured to control the valve based on the temperature measured by the temperature sensor.
8 . The system according to claim 7 , wherein the control system is configured to compare the temperature measured by the temperature sensor to a lower threshold and to bypass the heat exchanger when the temperature is below the lower threshold.
9 . The system according to claim 1 , wherein the heat exchanger comprises a radiator and a fan.
10 . The system according to claim 9 , wherein the fan is hydraulically operated via the hydraulic fluid flowing through the hydraulic circuit.
11 . The system according to claim 1 , further comprising a coolant system in which a coolant flows through a coolant circuit to cool the motor so as to prevent the motor from overheating.
12 . The system according to claim 11 , wherein the heat exchanger comprises a first radiator and a second radiator, and wherein the first radiator is operatively connected within the hydraulic circuit so as to provide heat exchange for the hydraulic fluid, and wherein the second radiator is operatively connected within the coolant circuit so as to provide heat exchange for the coolant.
13 . The system according to claim 12 , wherein the first pump and the second pump are both operated by the motor.
14 . The system according to claim 12 , further comprising a fan configured to cool both the first radiator and the second radiator.
15 . The system according to claim 11 , wherein the coolant system comprises a pump for circulating the coolant through the coolant circuit, further comprising a temperature sensor that measures a temperature of the coolant within the coolant circuit, wherein the control system is configured for operating the pump based on the temperature of the coolant within the coolant circuit.
16 . The system according to claim 1 , wherein the displacement of the first pump is controllable via a digital directional control valve operatively coupled thereto.
17 . A system for retarding a railcar having wheels, the system comprising:
a brake and an actuator configured to move the brake between a closed position in which the brake contacts the wheels of the railcar and an open position in which the brake does not contact the wheels of the railcar;
a hydraulic circuit through which a hydraulic fluid flows between the actuator and a reservoir;
a first pump operably connected within the hydraulic circuit and configured to provide the hydraulic fluid to the actuator for operating the brake;
a heat exchanger operably connected within the hydraulic circuit and configured to cool the hydraulic fluid flowing therethrough, wherein the heat exchanger prevents the hydraulic fluid within the hydraulic circuit from exceeding a target operating temperature;
a second pump operably connected within the hydraulic circuit and configured to provide the hydraulic fluid to the heat exchanger;
a motor that operates at least one of the first pump and the second pump; and
an enclosure in which the first pump, the second pump, and the motor are situated for protection, wherein the enclosure comprises a housing and a cover separated from the housing, wherein the cover at least partially shades the housing, and wherein the cover is positioned above the housing such that a gap remains therebetween to provide a thermal buffer between the housing and the cover.
18 . The system according to claim 17 , wherein an opening extends through a top of the housing, and wherein the cover is positioned at least over the opening to prevent ingress into the housing from above.
19 . A method for cooling a system for slowing a railcar, the system including a brake that slows the railcar when in a closed position and does not slow the railcar when in an open position, and the system further including an actuator that moves the brake into and between the closed position and the open position, wherein the actuator is fluidly coupled to a reservoir and a pump to form a hydraulic circuit and the pump is operated by a variable speed motor, the method comprising:
measuring a temperature of hydraulic fluid within the hydraulic circuit and comparing the temperature to a threshold;
controlling a valve to cause the hydraulic fluid to flow to a heat exchanger when the temperature of the hydraulic fluid exceeds the threshold, and controlling the valve to cause the hydraulic fluid to bypass the heat exchanger when the temperature of the hydraulic fluid is less than the threshold, wherein the heat exchanger is configured to exchange heat with the hydraulic fluid to prevent the temperature of the hydraulic fluid from exceeding a target operating temperature;
measuring a pressure of the hydraulic fluid within the hydraulic circuit; and
controlling a speed of the variable speed motor and controlling a displacement of the pump during operation thereof based on the pressure of the hydraulic fluid.
20 . A method for cooling a system for slowing a railcar, the system including a brake that slows the railcar when in a closed position and does not slow the railcar when in an open position, and the system further including an actuator that moves the brake into and between the closed position and the open position, the method comprising:
fluidly coupling the actuator, a reservoir, and a pump operated by a variable speed motor to form a hydraulic circuit through which a hydraulic fluid flows;
fluidly coupling the variable speed motor to a coolant circuit through which a coolant flows, wherein the coolant remains fluidly isolated from the hydraulic fluid;
changing a displacement of the pump and a speed of the variable speed motor during operation thereof; and
circulating the coolant through the coolant circuit to prevent the variable speed motor from overheating during operation of the system for slowing the railcar.