Patent ID: 6354617
Filing Date: 2002-03-12
Classification: B60G,Y10T

Abstract:
A level control arrangement for a vehicle comprising:a plurality of air springs mounted on said vehicle; a pressurized air source for supplying pressurized air; an air dryer connected to said pressurized air source; valve means for connecting said pressurized air source to said air springs via said air dryer for filling said air springs; a pneumatically controllable first directional valve for connecting said pressurized air source with the atmosphere when a pregiven pumping pressure is exceeded; a venting line providing a path via which said air springs can communicate with the atmosphere for releasing pressurized air thereinto from said air springs; said venting line being lead through said first directional valve and said air dryer; said first directional valve having a pneumatic control input; a control line leading to said pneumatic control input and being connectable to at least one of said air springs so as to permit said pneumatic control input to be charged with pressurized air of said at least one of said air springs; a controllable second directional valve connected in said control line between said first directional valve and said air springs and switchable to connect and disconnect said first directional valve from said air springs; said first directional valve including: a housing; a first piston displaceably mounted in said housing for movement between a first position and a second position and said first piston having a catch formed thereon; a first seat on which said first piston sits when in said first position; a first spring for resiliently biasing said first piston against said first seat in said first position; said first piston being liftable from said first seat against the return force of said first spring when said pneumatic control input is charged with the air pressure of at least one of said air springs; a second seat connectable to the atmosphere; a second piston displaceably mounted in said housing; a second spring for resiliently biasing said second piston against said second seat for blocking a connection to the atmosphere via said second seat; said second piston being operatively connected to said first piston and having an end face chargeable with pressurized air from said pressurized air source and from said venting line; said second piston being lifted from said second seat against the return force of said second spring via said catch when said first piston is lifted from said first seat or by the pressurized air from said pressurized air source when said pressurized air from said pressurized air source exceeds a pregiven pumping pressure and then at least one of said air springs and/or said pressurized air source is connected with the atmosphere; said venting line being guided through said first directional valve separately from said control line; and, said venting line being blocked by said first piston when said first piston is seated on said first valve seat and cleared when said first piston has lifted from said first seat so that air from at least one of said air springs are discharged into the atmosphere.