Ratio relay emergency valve system for vehicles

In a brake system for a vehicle system having two sets of brakes, a front set and a rear set of brakes and including a source of fluid pressure, a driver controlled valve, said sets of brakes responsive to fluid pressure from said source via said driver controlled valve, said brake system including a secondary valve having at an input port, a connection to said driver controlled valve and its output port coupled to said rear brakes, and in which said secondary valve means produces an increase in pressure at the output port above the pressure of said input port, the improvement comprises:

• said secondary valve including time delay means for bleeding excess pressure at said outlet port to reduce the pressure at said output port to substantially the pressure at said inlet port after the application of pressure to said inlet port by operation of said driver controlled valve;
• wherein said secondary valve means includes a piston having a first side communicating with said inlet port and a second side communicating with said outlet port;
• said piston defining an orifice therethrough for transfer excess pressure from said outlet port to a point in said system to substantially equalize the pressure at said inlet port;
• said orifice dimensioned to provide restricted flow of fluid from said outlet port side to said inlet port side.

In a brake system for a vehicle system having two sets of brakes, a front set and a rear set of brakes and including a source of fluid pressure, a driver controlled valve, said sets of brakes responsive to fluid pressure from said source via said driver controlled valve, said brake system including a secondary valve having at an input port, a connection to said driver controlled valve and its output part coupled to said rear brakes, and in which said secondary valve means produces an increase in pressure at the output port above the pressure of said input port, the improvement comprises:

• said secondary valve including time delay means for returning excess pressure at said outlet port to reduce the pressure at said output port to substantially increase the pressure at said inlet port after the application of pressure to said inlet port by operation of said driver control valve;
• wherein said secondary valve means includes a piston having a first side communicating with said inlet port and a second side communicating with said outlet port;
• said piston defining an orifice therethrough for transfer excess pressure from said outlet port to a point in said system to substantially equalize the pressure at said inlet port;
• said orifice dimensioned to provide restricted flow of fluid from said outlet port side to said inlet port side;
• including first seal means for sealing the larger area region at said piston to a corresponding larger area region of said cylinder and second seal means for sealing the smaller area of said piston to a corresponding smaller area region of said cylinder and wherein said first and second orifices bypass said second seal means.

A ratio relay emergency valve comprising:

• a valve body including
• an input port for the application of actuating pressure;
• at least one outlet port;
• said body defining a cylinder including a larger area region and smaller area region, said larger area region communicating with said inlet port, said smaller area region communicating with said outlet port;
• a piston having a large area region for travel through the large area region of said cylinder and a smaller area region for travel through said smaller area region to said cylinder;
• whereby the application of actuating pressure to the said inlet port applies a pressure to said outlet port which is an inverse function of the smaller area to the larger area of said cylinder and piston, the improvement wherein:
• the said piston includes a flow restricting orifice communicating between the smaller and larger area portions of said piston whereby upon the application of pressure to the inlet port of said valve provides an initial pressure at the outlet port greater than the pressure at said inlet port followed by substantially equal pressure after a period of time.