BRAKE SYSTEM FOR A LIGHT RAIL VEHICLE

• US 3,845,991 A
• Filed: 08/31/1973
• Issued: 11/05/1974
• Est. Priority Date: 08/31/1973
• Status: Expired due to Term

• Current Assignee: Knorr Brake Holding Corporation (Knorr-Bremse GmbH)
• Original Assignee: Thomas Engle
• Inventors: Engle, Thomas
• Primary Examiner(s): Reger, Duane A.
• Application Number:
  US05/393,529
• Time in Patent Office: 431 Days
• Field of Search: 303/3,15-18,20,21A,22A
• US Class Current: 303/3
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 2240/30 Parking brake position
• CPC Class Codes: B60L 3/108 whilst braking, i.e. ABS
• CPC Class Codes: B60L 7/006 Dynamic electric braking by reversing current, i.e. plugging
• CPC Class Codes: B60L 7/26 Controlling the braking effect
• CPC Class Codes: B60T 13/44 with two-chamber booster units
• CPC Class Codes: B60T 13/586 the retarders being of the electric type
• CPC Class Codes: B60T 13/665 the systems being specially adapted for transferring two or more command signals, e.g. railway systems B60T13/662 takes precedence
• CPC Class Codes: B60T 13/74 with electrical assistance or drive
• CPC Class Codes: B60T 8/1893 especially adapted for railway vehicles
• CPC Class Codes: B60T 8/3235 Systems specially adapted for rail vehicles
• CPC Class Codes: B61H 5/00 Applications or arrangements of brakes with substantially radial braking surfaces pressed together in axial direction, e.g. disc brakes self-applying brakes B61H11/02; combinations of different types of brakes B61H11/14; discs adapted for mounting on the wheel of a railway vehicle F16D65/124
• CPC Class Codes: F16D 2125/026 Pressure-to-pressure converters, e.g. hydropneumatic
• CPC Class Codes: F16D 55/2245 in which the common actuating member acts on two levers carrying the braking members, e.g. tong-type brakes similar brakes for rail vehicles B61H5/00
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility

Abstract

A brake system for a light rail vehicle having both dynamic and friction braking systems is disclosed. The system has three individual and redundant systems which act independently on each truck. The system uses a dynamic brake means which converts the propulsion motors to brake motors as the prime braking means. The system includes a fluid operated friction brake system with a blending means to supplement the dynamic braking with friction braking as needed to achieve the total braking force required. The system includes an air spring and variable load means to regulate the maximum amount of fluid pressure available for the friction brake means to prevent over application of the friction brakes and skidding of the wheels. The system further includes an independent hand brake means which affects actuation of the friction brake.

Claims

1. A brake system for light rail vehicles comprising a. a dynamic brake for said vehicle, said brake including means for generating variable electric current upon application of the dynamic brake, said means including an impedance to receive at least a portion of the variable current generated by said dynamic brake, b. fluid operated friction brakes for said vehicle, said brakes including means responsive to variations in fluid pressure for actuating said friction brakes, c. electrical control means for energizing said dynamic brake and said fluid operated friction brakes to effect braking of the vehicle, d. fluid pressure control means for providing variations in the fluid pressures applied to said friction brake means, said control means including 1. blending means for adjusting the fluid pressure applied to said friction brakes, said blending means including an electropneumatic transducer which responds to variations in both the electrical current received by said impedance and an electrical current produced by said electric control means, to vary the fluid pressure supplied to said friction brakes, 2. variable load valve means for controlling the fluid pressure supplied to said blending means, said means including an air spring and proportional valve, said valve being responsive to pressure variations in said air spring to vary the fluid pressures supplied to said blending means, and e. a skid controller including detector means for detecting skid condition and a release valve actuated by said controller for venting the fluid pressure supplied to said friction brakes, when said detector means detects a skid condition.

2. variable load means for controlling the fluid pressure supplied to said blending means, said means including an air spring and a variable control valve responsive to pressure in said air spring to vary the fluid pressure supplied to said blending means, e. hand brake control means, said means including a vent valve for reducing the pressure acting on the second fluid motor of said fluid brakes to affect actuation of said spring motor means.

3. A brake system for light rail vehicles as claimed in claim 2 which further comprises a hydraulic motor means between said first fluid motor and said friction brake to provide hydraulic brake pressure to said friction brake to effect actuation thereof.

4. A brake system for light rail vehicles as claimed in claim 3 which further comprises hydraulic slack adjusting means mounted between said hydraulic motor means and said friction brake.

5. A brake system for light rail vehicles as claimed in claim 4 wherein said slack adjusting means comprises a pair of expansible chamber hydraulic devices having first and second working spaces normally isolated from each other by movable reaction elements, said means including a transfer valve means responsive to the movement of said reaction elements to permit flow from said first working space to said second working space when the volume of said second working space is at its minimum.

6. A brake system for light rail vehicles as claimed in claim 2 which further comprises hand brake control means, said means including a vent valve for reducing the pressure acting on said second fluid motor to affect actuation of said spring motor means.

7. A brake system for light rail vehicles as claimed in claim 2 wherein said blending means further comprises a. first and second torque motors, said first torque motor responding to electrical variations in the current received by said impedance, said second torquE motor responding to said electrical current produced by said electric control means, b. proportioning valve means connected between said variable load valve means and said fluid operated friction brakes, said means effective to vary the fluid pressure supplied to said friction brakes, said proportioning valve responding to variations in a pilot fluid pressure, c. transducer means responsive to the sum of the combined outputs of said first and second torque motors to vary the pilot pressure for said proportioning valve.

8. A brake system for light rail vehicles as claimed in claim 7 wherein said proportioning valve further comprises a self-lapping supply and exhaust valve.

9. A brake system for light rail vehicles as claimed in claim 7 wherein said means responsive to said variations and fluid pressure include a. first and second pressure responsive fluid motors, ssid first fluid motor responsive to positive fluid pressure variations from said blending means to actuate said friction brakes, b spring motor means restrained by said second fluid motor, said spring motor being released by reductions in the fluid pressure acting on second said fluid motor, thereby to actuate said friction brakes.

10. A brake system for light rail vehicles comprising a. a dynamic brake for said vehicle, said brake including means for generating variable electric current current upon application of said dynamic brake, said means including an impedance to receive at least one portion of the variable current generated by said means, b. fluid operated friction brakes for said vehicle, said brakes including first and second pressure responsive fluid motors, said first fluid motor being responsive to positive fluid pressure variations to actuate said friction brakes, said brakes also including spring motor means restrained by said second fluid motor, said spring motor being released by reductions in the fluid pressure acting on said second fluid motor, thereby to actuate said friction brakes, c. electrical control means for energizing the dynamic brake and a fluid pressure control means for said friction brakes, to effect the friction braking of the vehicle, d. fluid pressure control means for providing variations in the fluid pressure applied to said friction brakes, said control means including

11. A brake system for light rail vehicles as claimed in claim 10 which further comprises a hydraulic fluid motor means mounted between said first fluid motor and said friction brake to provide hydraulic brake pressure to said friction brake to affect actuation thereof.

12. A brake system for light rail vehicles as claimed in claim 11 which further comprises hydraulic slack adjusting means mounted between said hydraulic fluid motor means and said friction brake.

13. A brake system for light rail vehicles as claimed in claim 10 wherein said blending means further comprises a. first and second torque motors, said first torque motor being responsive to electrical current received by said impedance, said second torque motor being responsive to said electrical current produced by said electrical control means. b. said proportioning valve means connected between said variable load means and said fluid operated friction brakes, said valve means being effective to vary the fluid pressure supplied to said brake means in response to pilot pressure produced by a transducer, c. transducer means responsive to the output of said torque motors and the pressure supplied to said friction brakes to vary the pilot pressure supplied to said proportioning valve.

14. A brake system for light rail vehicles as claimed in claim 13 wherein said proportioning valve comprises a self-lapping supply and exhaust valve.

15. A brake system for light rail vehicles as claimed in claim 2, wherein said electropneumatic transducer is further responsive to the fluid pressure supplied to said friction brake.

16. A brake system for light rail vehicles as claimed in claim 10, wherein said pressure transducer is further responsive to the variable current received by said impedance.