Pressurized fluid, is commonly utilized for powering a variety of fluid operated systems, particularly on vehicles, such as, but not limited to, work machines such as tractors and the like. Such systems can include, but are not limited to, a transmission, a brake system, and a steering control system. Mechanical regulators, including pressure regulator valves, have long been utilized for regulating the pressure of fluid utilized by such systems. More recently, electrically controlled pressure regulator valves have been used. Advantages of electrically controlled regulators include a precise ability to respond to changing conditions, programmability, reliability, cost and light weight. However, with electrically controlled devices, a disadvantage is that there is the possibility of loss or interruption of electrical power, and/or failure or malfunction of the electrical components or devices. To overcome such an occurrence, it would be advantageous to provide a manner of at least limited operation of the regulator, for delivery of regulated fluid flow at some minimum regulated pressure to the using system or systems, particularly more critical systems, such as the transmission, brakes, and steering.
Accordingly, what is sought is an electrically controlled pilot operated pressure regulator valve apparatus providing at least one of the advantages, and overcoming at least one of the disadvantages, problems, and/or shortcomings, set forth above.
USPTO Backgrounds
USPTO Backgrounds