Lumber support system for a vehicle seat

Abstract

A lumber support system comprising an air bag disposed behind the upholstery sheet of a vehicle seat, a manual air pump and a valve assembly for controlling the supply of air from the manual air pump into the air bag as well as the discharge of the air contained in the air bag. The valve assembly comprises a valve casing being attached to the vehicle seat and provided with a partition wall partitioning the interior of the valve casing into first and second chambers, an inlet port for allowing the communication of the first chamber with the outlet of the manual air pump, a discharge port for allowing the communication of the first chamber with the exterior of the valve casing, an outlet port allowing the communication of the second chamber with the air bag, a manually operable push button movably supported on the valve casing, a first normally closed valve formed within the first chamber for normally closing to interrupt the communication between the first chamber and the discharge port and adapted to be opened when the push button is depressed manually, and a second normally closed valve formed within the second chamber for normally closing an opening formed on the partition wall to interrupt communication between the first and second chambers therethrough and adapted to be opened when pressurized air is supplied into the first chamber and when the first normally closed valve is opened.