Patent Application
20180093649
The present invention relates to electronic brake valves and, more specifically, to an electronic brake valve having independently adjustable friction and detent torque.
An electronic brake valve (EBV) is the human interface for a computer controlled train braking system and includes a EBV controller having one or more handles that may be moved by the train operator to selectively apply and release the train brakes. The handles may be positioned in a number of predetermined locations that correspond to certain brake applications, e.g., brakes released, full service, or emergency service. The ease with which the handles of a brake controller are moved is referred to as “handle feel” and different railroads often have different preferences for EBV handle feel. Handle feel can be characterized by the amount of force (torque) needed to move the handle between detents (friction torque) and the amount of force needed to move the handle out of a detent (detent torque plus friction torque). The ratio of friction torque to detent torque determines how smoothly and precisely the handle can be moved out of a detent and into a friction zone. Currently, these two types of torque have a fixed ratio for a particular set of components. Thus, in order to set or adjust the amount of torque in a conventional EBV handle, the components must be specifically selected prior to assembly of the controller or replaced in an existing controller to achieve the desired handle feel. As handle torque may change over time due to wear, restoring the originally selected handle feel requires replacement of worn handle components. Accordingly, there is a need in the art for an EBV handle system that has a handle feel that can be easily adjusted, whether at assembly and installation, or at later date, without having to change or replace handle components.
The present invention is a brake controller having independently adjustable friction and detent torques and thus may be adjusted to have a desired handle feel without having to change components of the brake controller. The brake controller has a user handle rotatable into and between a series of predetermined positions, a cam associated with the user handle for rotation therewith, a first spring assembly providing a first biasing force resisting rotation of the cam, and a second spring assembly providing a second biasing force resisting rotation of the cam. The first spring assembly comprises a lever, a roller carried by the lever, and a first spring positioned to provide a first biasing force urging the roller into contact with the cam. The cam includes an outer circumference having a series of divots corresponding to the series of predetermined positions into which the roller may extend when the handle is rotated. A screw associated with the first spring that may be turned to increase or decrease compression of the first spring. The second spring assembly comprises a second spring positioned to provide a second biasing force urging a lateral surface of the cam into a frictional surface. The second spring includes a spring cup that may be rotated to increase or decrease compression of the second spring.
According to the present invention, a brake controller may be adjusted to a desired handle feel by independently adjusting the friction and detect torques of a brake controller. The method of adjusting the handle feel of the brake controller includes changing the detent torque by changing the compression of a first spring that provides a first biasing force resisting the rotation of a cam that is interconnected to and rotatable with a user handle of the brake controller. The first spring preferably urges a roller into engagement with the outer circumference of the cam, which includes a series of divots corresponding to conventional brake handle positions. The friction torque is then adjusted by changing the compression of a second spring that provides a second biasing force resisting the rotation of the cam. The second spring preferably urges a lateral side of the cam into engagement with a frictional surface.
The present invention will be more fully understood and appreciated by reading the following Detailed Description in conjunction with the accompanying drawings, in which:
Referring to the figures, wherein like numerals refer to like parts throughout, there is seen in
Referring to
Referring to
A cam 64 is fixedly attached to shaft 28 on the opposing side of outer plate 26 from handle 22 for co-rotation with handle 22. Cam 64 includes a series of divots 66 formed in its outer circumference that correspond to the established industry brake handle positions, e.g., full service, emergency service, etc. A first spring assembly 68 provides a biasing force against the outer circumference of cam 64 that resists rotation of cam 64. Spring assembly 68 includes a pivoting lever 70 having a detent roller 72 is positioned so that detent roller 72 engages the outer circumference of cam 64 and is biased to fall into divots 66 when rotated by handle 22 into proximity therewith. Lever 70 includes a recess 74 for housing a detent spring 76, seen in
Referring to
The friction torque required to move handle 22 between detent positions is controlled by the coefficient of friction of friction surface 86 and the amount of force pressing cam 64 against friction surface 86. Thus, rotation of hexagonal spring cup 94 can change the friction toque by adjusting the amount of force being applied by spring 96. Similarly, detent torque may be adjusted using adjustment screw 78 to change the amount of force that spring 76 applied to lever 70 and thus the amount of force urging detent roller 72 against the peripheral edge of cam 64 and into any divot 66. As seen in
The kinetic and static coefficient of friction of friction surface 86, in conjunction with the ratio of friction and detent torque, provide for smooth and controllable handle adjustments without any jerking or jumping when movement is initiated by a user. Adjustable controller 10 also avoids the need for railroads or owners of controller 10 to track which particularly components are needed in any controller 10 to achieve the desired handle feel as any controller 10 can be adjusted to meet the desired feel and repaired using the same components as any other controller 10. The design of controller 10 also improves the longevity of controller 10 as the torque generating interfaces, i.e., detent roller 74 and friction disk 84, are specifically designed for generating torque and thus are more robust that the conventional handle components that provide a given amount of torque simply because of their composition and design.
