Patent Application
20090121539
The present disclosure relates to locomotive brake systems and more specifically to a brake pipe vent valve for locomotive brake systems.
A locomotive brake system generally includes a brake valve with brake handles, e.g., an automatic brake handle and an independent brake handle to provide control signals to a brake control valve. The brake control valve controls the brake cylinder and the brake pipe. The brake control valve provides service brake, emergency brake, and release brake signals on the brake pipe. Connected at each end of the locomotive are vent valves which are responsive to an emergency condition in the brake pipe to exhaust the brake pipe and accelerate the transmission of the emergency signal. The brake valve includes an emergency valve which is responsive to the emergency position of the automatic brake handle to also vent the brake pipe. In some systems this is connected directly to the brake pipe or it is connected to the brake control valve to vent the brake pipe. The brake control valves may include a brake pipe vent valve which is responsive to electric signals from the brake valve or other safety valves, e.g., dead man's switch or various penalties to also vent the brake pipe in response to unsafe conditions. The vent valve is only responsive to an emergency condition in the brake pipe. The discussion of the prior art systems will be described with respect to
The present locomotive brake system includes a brake controller operable by an operator, a brake valve and a brake pipe vent valve. The brake controller includes an emergency output port which provides an operator emergency pneumatic signal on the emergency output port when the brake controller is in an emergency position. The brake valve is responsive to brake signals from the brake controller for generating brake signals on a brake pipe.
The brake pipe vent valve includes a housing having brake pipe, emergency input and exhaust ports, and first and second valves. The emergency output port is fluidly connected to the emergency input port and the brake pipe port is connected to the brake pipe. The first valve selectively connects the brake pipe port to the exhaust port when opened in response to an emergency signal on the brake pipe port The second valve selectively connects the brake pipe port to the exhaust port when opened in response to the operator emergency signal on the emergency input port.
The first valve opens is responsive to a greater pressure in a first volume, which is connected to a second volume by a choke, than pressure in the second volume, which is connected to the brake pipe port. The second valve opens is responsive to a smaller pressure in a third volume, which is connected to the emergency input port, than pressure in a fourth volume, which is connected to the brake pipe port.
The first valve opens in response to the second valve being open and also in response to the emergency pressure in the brake pipe. The second valve opens only in response to the operator emergency signal on the emergency input port.
These and other aspects of the present disclosure will become apparent from the following detailed description of the disclosure, when considered in conjunction with accompanying drawings.
One of the brake control systems of the prior art is illustrated in
The emergency vent valve EMRV of
A vent valve VV of the prior art is illustrated in
A later version of the locomotive brake system is illustrated in
Valve 40 is also known as the PVEM in the described patent. Chamber 44 is also connected to a magnetic valve MVEM 52 and a magnetic emergency valve EMV 54 via emergency input pilot port 58. These are under control of the electronic brake valve EBV or other systems within the locomotive. When the electropneumatic valves 52,54 are actuated, they move from the position shown to their second position which connects chamber 44 to exhaust EXH. This causes the PVEM valve 40 to move from the position shown to a second position connecting brake pipe BP to exhaust EXH. Chamber 44 is also connected at port 58 by 56 to the #21 pipe which is connected to the EMRV valve in the EBV as well as to other safety valves within the locomotive. This will also connect chamber 44 to exhaust causing the PVEM valve 40 to move to the position where the brake pipe BP is connected to exhaust EXH. As previously discussed, the PVEM valve 40 is responsive to the signal on port 58 and is not responsive to brake pipe which is only used to charge the chambers 42 and 44.
The vent valve of the present disclosure in a brake system is illustrated in
A detailed structure is illustrated in
As previously discussed, the #21 pipe is pressurized during normal conditions and during an emergency position of the automatic brake valve AB the pressure in the #21 pipe goes to zero. Thus when the automatic brake handle AB is in the emergency position, port 58 and chamber 64 is exhausted and the brake pipe pressure in chamber 62 forces the valve to its second position connecting the brake pipe BP to exhaust EXH. Activation of valves MVEM 52 and EMV 54 will also connect port 58 and chamber 64 to exhaust EXH. When the brake pipe is connected to exhaust, it also reduces the pressure in chamber 32 causing the vent vale 30 to assume its open position also connecting brake pipe BP to exhaust EXH. This parallel connection of the brake pipe to exhaust through the two open valves increase the capacity and therefore further accelerates the depletion of the pressure in the brake pipe accelerating the emergency signal down the brake pipe. The capacity of valve 62 may be equal to the capacity of valve 30 or may be small.
The valve 60 is not responsive to the pressure in the brake pipe and is maintained in the closed position as long as there is pressure in chamber 64 indicating that the automatic brake valve AB is not in the emergency position and neither of emergency valves MVEM 52 and EMV 54 are activated. Thus the valve 30 is responsive to both an emergency signal on the brake pipe as well as the opening of the valve 60 to exhaust whereas the valve 60 is only responsive to the emergency signal on port 58 from the electronic brake valve EBV and brake pipe valve BPV.
An embodiment or implementation of the dual vent valve DDV is illustrated in
The brake pipe port BP is connected through filter 114 to chamber 32 of valve 30. It is also connected to chamber 62 of the valve 60. The emergency input pilot port EP 58 is connected to chamber 64 of valve 60. Body portion 120 maintains spring 68, diaphragm piston 122, spring 130 and valve element 124 in the main housing portion 102. The diaphragm piston 122 is secured between the housing portions 102 and 120. The valve element 124 rests on valve seat 126. Spring 130 provides a loss motion between stem 128 of the piston and the valve element 124.
As can be seen, chamber 32 is responsive to a drop of pressure in the brake pipe port BP or from opening of valve 60. Valve 60 is only responsive to a drop in pressure at the emergency pilot port 58.
Although the present disclosure had been described and illustrated in detail, it is to be clearly understood that this is done by way of illustration and example only and is not to be taken by way of limitation. The scope of the present disclosure is to be limited only by the terms of the appended claims.
