Patent Application
20050252322
The present invention generally relates to the field of master controllers for railway vehicle use, and more particularly, to master controller mechanical interfaces such as those used on railway propulsion or braking systems.
In modern rapid transit vehicles, such as railway vehicles, the braking and propulsion controls are often effected by a master controller. These master controllers typically include an operator interface, such as a handle, which can be moved from a neutral or coast position to either a propulsion or braking position to provide a control signal throughout the vehicle. Two additional controls are also commonly coupled to the operator interface on a master controller, a key switch and a direction switch. The key switch can be placed in one of several positions, which typically include an off, run, and special charge position. There may be fewer or additional positions, and the name for each position may also differ. The direction switch can either be in a locked position (neutral) or in one of two operational positions (left and right). The key switch is used to allow the master controller to function, and the direction switch is used to select the vehicle's desired direction (forward or reverse).
Recent master controller construction techniques include an operator's interface, such as a handle, which is connected to a cam that operates a series of microswitches or position sensors. These microswitches or sensors, in certain conditions, operate motor control relays. It is desirable, however, to prevent the operation of the key switch or the direction switch in certain configurations of the handle position. Should the switches be operated in an undesired configuration, the vehicle could be turned off without application of the brakes; the direction of the vehicle could be changed while the operator interface (handle) is in a propulsion position; or in the special charge mode (or test mode), the brakes must be applied or an operator or inspector could be injured should the vehicle move. Thus, it is an object of the present invention that undesired operation of the master controller be prevented.
The present invention generally relates to mechanical interlocks. An interlock system is described as applied to a master controller in such a manner as to allow operation of the master controller only in a prearranged configuration. A series of mechanical cam mechanisms are used to lock selected operations of the master controller to prevent undesired user selected configurations.
In one illustrative embodiment of the present invention, a disk cam is affixed to at least one of two user switches. A linear cam follower having a preconfigured surface is then allowed to travel on the surface of the disk cam, causing at least one additional linear roller follower to secure the master controller from entering an undesired configuration.
In some embodiments, multiple switches may be employed and multiple linear roller followers are allowed to travel on the surface of the linear cam follower, increasing the ability to limit operation of the master controller to only those specific conditions where both switches are in predetermined positions.
The invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which:
While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular illustrative embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
The following description should be read with reference to the drawings, in which like elements in different drawings are numbered in like fashion. The drawings, which are not necessarily to scale, depict selected embodiments and are not intended to limit the scope of the invention. Although examples of construction, dimensions, and materials may be illustrated for the various elements, those skilled in the art will recognize that many of the examples provided have suitable alternatives that may be utilized.
Generally, the present invention pertains to mechanical interlocks such as, for example, mechanical interlocks having at least one cam member. The present invention is applicable for use on mechanical interfaces which traditionally use numerous rotary cams to actuate interlocks between interacting controls. An appreciation of various aspects of the present invention will be gained through a discussion of the illustrative embodiments provided below. While the illustrative embodiment discusses the use of the present invention in a rail car application, one skilled in the art will find the invention can be used in any mechanical interlock application.
An operator interface, shown by reference numeral 1, is shown as a handle and commonly used to send a braking, coast, or propulsion signal throughout the vehicle. This operator interface could also take the form of a lever or other object capable of passing motion to the mechanical interlock. More specifically, the operator interface can be placed in any one of the following positions: locked emergency, emergency, full service brake, braking, coast, power, and locked full service brake. As will be explained in detail below, depending on the configuration of the mechanical interlock, any number of these functions may or may not be available to the operator of the vehicle.
Also shown are two switches, a key switch 2, and a direction switch 4. When an operator inserts and turns the key switch 2, it actuates the mechanical interlock so as to allow operation of the direction switch 4 and the operator interface 1 in selected predetermined positions.
Direction switch 4 can typically be placed in either a locked neutral (LN) or a locked any (LA) position, depending on the position of the key switch 2 and the operator interface 1.
Linear cam follower 5 may be manufactured from any material which will provide the strength and wear properties required for the intended application, such as hardened steel. The shape of linear cam follower 5 is chosen for the master controller by developing the linear logic necessary to effectuate the desired interlocking operation. This is easily accomplished by determining the desired Y position of each linear roller follower 8 and 9 for any specific operator control input, including and any incremental position between fully extended and fully retracted, and then by mapping each desired linear cam follower Y position for all X positions of the linear cam. The linear cam is then machined or cut so that the radius causes the linear roller followers 8 and 9 to actuate accordingly.
The linear cam follower 5 is mounted, preferably in bearings, to allow free movement in the X direction. Linear roller followers 7 and 11 are secured on the end of each disk cam 3 and 6, which allows the linear roller followers 7 and 11 to ride or travel on each disk cam 3 and 6. While
When key switch 2 of
The logic for positions of the key switch, directional switch, and allowable operator interface positions can be shown by the following table:
The present invention should not be considered limited to the particular example described above, but rather should be understood to cover all aspects of the invention as fairly set out in the attached claims. Various modifications, equivalent processes, as well as numerous structures to which the present invention can be applicable will be readily apparent to those of skill in the art to which the present invention is directed upon review of the instant specification.
