Override control for a diverter valve

Claim 2

In a vehicle having a servomotor for providing an operational force to activate a power braking system and a pump for providing a supply of air under pressure to operate an emission control system, diverter valve means for directing said supply of air away from said emission control system in response to an operational condition in the engine of said vehicle, the improvement comprising: override control means connected to said diverter valve means and said servomotor for interrupting the supply of air to the emission control system, independently of said operational condition in the engine, and causing the supply of air to be communicated to the servomotor as an operational power supply in response to a sensed braking potential.

Claim 3

In the vehicle, as recited in claim 1, wherein said override control means comprising: a housing having a bore therein, said bore having a first port, a second port, a third port, and a fourth port, said first port and said fourth port being connected to a passageway joining the servomotor to the pump, said second port being connected to the atmosphere, and said third port being connected to the diverter valve means; and shuttle means responsive to the supply of air under pressure communicated to the first and fourth ports for selectively allowing air to freely flow in through the second port and out the third port to provide an operational control for the diverter valve means in a first mode of operation and for allowing air under pressure to flow in through the fourth port and out the third port to nullify the effect of the operational control on the diverter valve means to permit the output supply of air from the pump to be directed into the servomotor in a second mode of operation.

Claim 4

In the vehicle, as recited in claim 2, wherein said shuttle means includes: a first piston located in said bore for separating the first port from the second port to form a sensing chamber therebetween for monitoring the pressure of the air in said passageway; and a second piston connected to said first piston and located in said bore between said fourth port and a wall in the housing separating the second port from the third port, said wall and first piston forming an atmospheric chamber in the bore adjacent the second port, said wall and the housing forming a transition chamber adjacent the third port, said first piston having a larger area exposed to the pressure of the air in said passageway than said second piston to develop a force for seating the second piston on the housing surrounding the fourth ports to maintain said first mode of operation.

Claim 5

In the vehicle, as recited in claim 3, wherein said override control means further includes: flow control means in a first branch passage of said passageway for preventing backflow of the air Under pressure communicated to the fourth port by maintaining a uniform pressure force on said second piston which opposes a varying pressure force on said first piston created by depletion of said air supply in the servomotor.

Claim 6

In the vehicle, as recited in claim 4, wherein said shuttle means further includes: resilient means located in said atmospheric chamber for providing additional opposition to movement of said first piston by the air under pressure in the sensing chamber.

Claim 7

In the vehicle, as recited in claim 5, wherein said housing further includes: a power chamber located between said flow control means and said fourth port for retaining a sufficient quantity of air under pressure to initially establish said second mode of operation.

Claim 8

In the vehicle, as recited in claim 5, wherein said override control means further includes: a restriction located in said passageway adjacent said first branch for controlling the rate at which the air supply under pressure will be communicated to said power chamber.

Claim 9

In the vehicle, as recited in claim 7, wherein said housing further includes: a second branch passage connected to the first port and the second branch passage between said flow control means and said restriction, said first branch passage having a larger sectional area than said second branch passage, said uniform pressure force acting on said second piston upon said depletion of the air supply in the sensing chamber to move said first piston in the bore and force air out the first port into the second branch passage past the flow control means and into the control chamber to aid in seating the second piston on the wall surrounding the second port to establish the second mode of operation.

Claim 10

In the vehicle, as recited in claim 8, wherein said override control means further includes: a storage reservoir located in said passageway for retaining a quantity of the air supply from the pump in said second mode to increase the pressure of the air therein, said restriction allowing the increase in pressure to gradually be communicated to the first and second branch passages, said increase in pressure in the sensing chamber acting on the first piston to move the second piston and seal the fourth port and re-establish the first mode of operation.

Claim 11

In the vehicle, as recited in claim 9, wherein said override control means further includes: float control valve means located on the bottom of said storage reservoir for removing condensation therefrom; and relief valve means attached to said storage reservoir for limiting the pressure of said air from the pump to a predetermined value.

Claim 12

In the vehicle, as recited in claim 10, wherein said override control means further includes: warning means connected to said storage reservoir and said servomotor means for indicating a potential operational pressure differential in the servomotor below a predetermined level to alert an operator of a potential braking deficiency in rapid deceleration.

Claim 13

Override means connected to a diverter valve in an emission control system of a vehicle for directing air under pressure into a reservoir supplying an operational fluid to a servomotor of a power braking system in response to a predetermined fluid pressure therein, said override means comprising: a housing having a control chamber, a transition chamber, an atmospheric chamber, and a sensing chamber located therein, said control chamber and said sensing chamber being connected by a first passageway, said first passageway being connected to a second passageway downstream from said control chamber, said first passageway having a larger sectional area than said second passageway, said second passageway being in communication with the fluid under pressure in the reservoir, said transition chamber being connected to said diverter valve, said control chamber, and said atmospheric chamber; shuttle means having a first face located in said sensing chamber and a second face locateD in said transition chamber, said first face having a larger area than said second face, said fluid under pressure acting on said first face in opposition to said fluid under pressure acting on said second face to prevent communication between said transition chamber and said control chamber and allow air from the atmospheric chamber into the transition chamber; restriction means located in said second passageway for regulating the rate by which the fluid under communication is transmitted to the control chamber and sensing chamber; and flow control means located in said control chamber for preventing backflow into said first passageway to maintain a uniform force on said second face to move the shuttle means and allow air under pressure into the transition chamber by forcing air in the sensing chamber into the control chamber to supply said diverter valve with an operational signal.

Claim 14

Override means connected to a diverter valve in an emission control system of a vehicle for directing air under pressure into a reservoir supplying an operational fluid to a servomotor of a power braking system in response to a predetermined fluid pressure therein, said override means comprising: a housing having a control chamber, a transition chamber, an atmospheric chamber, and a sensing chamber located therein, said control chamber and said sensing chamber being connected by a first passageway, said first passageway being connected to a second passageway downstream from said control chamber, said first passageway having a larger sectional area than said second passageway, said second passageway being in communication with the fluid under pressure in the reservoir, said transition chamber being connected to said diverter valve, said control chamber, and said atmospheric chamber; shuttle means having a first face located in said sensing chamber and a second face locateD in said transition chamber, said first face having a larger area than said second face, said fluid under pressure acting on said first face in opposition to said fluid under pressure acting on said second face to prevent communication between said transition chamber and said control chamber and allow air from the atmospheric chamber into the transition chamber; restriction means located in said second passageway for regulating the rate by which the fluid under communication is transmitted to the control chamber and sensing chamber; and flow control means located in said control chamber for preventing backflow into said first passageway to maintain a uniform force on said second face to move the shuttle means and allow air under pressure into the transition chamber by forcing air in the sensing chamber into the control chamber to supply said diverter valve with an operational signal.