Automatic vehicle leveling system having electronic pressure switch control

Claim 2

In an automatic leveling system for maintaining a predetermined height relationship between the sprung and the unsprung masses of a vehicle the combination of: fluid spring means including a control chamber pressurizable to produce a variable uplifting force to supplement the load-carrying capacity of a primary suspension spring and correct for deflection as produced by changes in static loading on the sprung mass, a pressure storage tank, a compressor having an inlet and an outlet, electric motor means for driving said compressor, said compressor outlet being in direct communication with the interior of said storage tank, a height controller responsive to changes in the height relationship between the sprung and unsprung mass, means including said height controller for communicating the interior of said tank with said fluid spring means during a fill phase of operation, means including said height controller for directly communicating said compressor inlet with said fluid spring means during an exhaust phase of operation a source of power, a pressure-responsive start switch connected to said source of power, holding circuit means for connecting said electric motor means to said source of power including a normally open relay-operated switch, said relay-operated switch having a coil energizable to close said switch, start circuit means including said pressure-responsive switch for sensing the pressure in said compressor inlet during the exhaust phase and being conditioned to energize said coil, means to maintain said coil energized to close said relay-operated switch for maintain said motor energized for a time delay period following opening of said pressure switch means to reduce the pressure at said compressor inlet thereby to pressure bias said pressureresponsive switch means to prevent contact chatter therein, and means for shunting said coil to cause said relay-operated switch to open following the predetermined time delay.

Claim 3

In a closed loop leveling system for maintaining a predetermined height relationship between the sprung and unsprung mass of a vehicle the combination of fluid spring means, a height controller responsive to changes in the height relationship between the sprung and the unsprung mass, a single conduit connected between said fluid spring means and said height controller, a pressure storage tank, a pressure switch and delay assembly on said tank, an exhaust conduit connected between said assembly and said height controller, a compressor having an inlet in communication with said assembly and an outlet directly communicating with the interior of said storage tank, said height controller being operative upon an increase in static load on the sprung mass of the vehicle to direct high-pressure fluid from the storage tank to said fluid spring means to support the added static load, said height controller directly communicating said fluid spring means with said exhaust conduit and assembly when static loading is removed from the sprung mass, a pressure-responsive start switch in said assembly sensing pressure in said exhaust conduit and operative in response thereto, an electric motor operatively connected to said compressor to operate said compressor so as to pump down said fluid spring means, a power source, an energization circuit for said electric motor including a hold switch with an energizable coil, means to energize said coil including said pressure start switch when it senses a high pressure in said exhaust conduit, said hold switch coil being connected to said power source on said hold switch during motor energization to maintain a hold circuit from said power source to said motor, means for shunting said coil and operative in response to opening of said pressure start switch to deenergize said coil to open said hold circuit, and timer means for preventing operation of said means for shunting for a delay period following opening of said pressure switch, said pressure switch including a pair of contacts and diaphragm means for operating said contacts open and closed in response to a single pressure, said compressor being operative during the delay period to pump down said exhaust conduit between said assembly and said height controller to establish a pressure on said diaphragm means of a magnitude to bias said contacts positively opened to prevent closing movement or chatter in response to vehicle road movements.

Claim 4

In a closed loop leveling system for maintaining a predetermined height relationship between the sprung and unsprung mass of a vehicle the combination of fluid spring means, a height controller responsive to changes in the height relationship between the sprung and the unsprung mass, a single conduit connected between said fluid spring means and said height controller, a pressure storage tank, a pressure switch and delay assembly on said tank, an exhaust conduit connected between said assembly and said height controller, a compressor having an inlet in communication with said assembly and an outlet directly communicating with the interior of said storage tank, said height controller being operative upon an increase in static load on the sprung mass of the vehicle to direct high-pressure fluid from the storage tank to said fluid spring means to support the added static load, said height controller directly communicating said fluid spring means with said exhaust conduit and assembly when static loading is removed from the sprung mass, a pressure-responsive start switch in said assembly sensing pressure in said exhaust conduit and operative in response thereto, an electric motor operatively connected to said compressor to operate said compressor so as to pump down said fluid spring means, a power source, an energization circuit for said electric motor including a hold switch with an energizable coil, means to energize said coil including said pressure start switch when it senses a high pressure in said exhaust conduit, said hold switch coil being connected to said power source on said hold switch during motor energization to maintain a hold circuit from said power source to said motor, means for shunting said coil and operative in response to opening of said pressure start switch to deenergize said coil to open said hold circuit, and timer means for preventing operation of said means for shunting for a delay period following opening of said pressure switch, said pressure switch including a pair of contacts and diaphragm means for operating said contacts open and closed in response to a single pressure, said compressor being operative during the delay period to pump down said exhaust conduit between said assembly and said height controller to establish a pressure on said diaphragm means of a magnitude to bias said contacts positively opened to prevent closing movement or chatter in response to vehicle road movements.

Claim 5

In an automatic vehicle-leveling system the combination of: fluid spring means for maintaining a predetermined height relationship between the sprung and unsprung mass of the vehicle, a pressure storage tank, a compressor having an outlet in direct communication with the interior of said pressure storage tank and an inlet, means for communicating said compressor inlet with said fluid spring means including a height controller and a pressure-responsive switch means, means for communicating the interior of said tank with said fluid spring means including said height controller, said height controller normally blocking communication to and from said fluid spring means when the vehicle is level, said height controller responding to a first predetermined relative movement between the sprung and unsprung mass to directly communicate the interior of said storage tank with said fluid spring means for producing a supplemental upward resultant force on the sprung mass, said controller being responsive to a second predetermined relative movement between the sprung and unsprung mass to directly communicate said fluid spring means with said pressure-responsive switch means, means for driving said compressor including an electric motor, an energization circuit for said electric motor including a hold switch operative when said fluid spring means are communicated by said height controller with said pressure-responsive switch means to energize said compressor motor so as to draw fluid through said compressor inlet from said fluid spring means, said hold switch having an energizable coil means including said hold switch maintaining said coil energized following motor energization, said electric motor being operative to draw down said fluid spring means to maintain a predetermined height relationship between the sprung and unsprung mass of the vehicle, and time delay means for operating said electric motor for a predetermined time period following return of the sprung and unsprung mass to their predetermined height relationship so as to maintain a predetermined pressure on said pressure-responsive switch means to prevent road induced movements from causing operation thereof during periods when the vehicle is level.

Claim 6

In an automatic vehicle-leveling system the combination of: fluid spring means for maintaining a predetermined height relationship between the sprung and unsprung mass of the vehicle, a pressure storage tank, a compressor having an outlet in direct communication with the interior of said pressure storage tank and an inlet, means for communicating said compressor inlet with said fluid spring means including a height controller and a pressure-responsive switch means, means for communicating the interior of said tank with said fluid spring means including said height controller, said height controller normally blocking communication to and from said fluid spring means when the vehicle is level, said height controller responding to a first predetermined relative movement between the sprung and unsprung mass to directly communicate the interior of said storage tank with said fluid spring means for producing a supplemental upward resultant force on the sprung mass, said controller being responsive to a second predetermined relative movement between the sprung and unsprung mass to directly communicate said fluid spring means with said pressure-responsive switch means, means for driving said compressor including an electric motor, an energization circuit for said electric motor including a hold switch operative when said fluid spring means are communicated by said height controller with said pressure-responsive switch means to energize said compressor motor so as to draw fluid through said compressor inlet from said fluid spring means, said hold switch having an energizable coil means including said hold switch maintaining said coil energized following motor energization, said electric motor being operative to draw down said fluid spring means to maintain a predetermined height relationship between the sprung and unsprung mass of the vehicle, and time delay means for operating said electric motor for a predetermined time period following return of the sprung and unsprung mass to their predetermined height relationship so as to maintain a predetermined pressure on said pressure-responsive switch means to prevent road induced movements from causing operation thereof during periods when the vehicle is level.

Claim 7

In the combination of claim 3, said time delay means including a transistor having its emitter and collector connected in shunt relationship to said coil, and means for producing a predetermined signal on the base of said transistor through means including said hold switch a predetermined time period following leveling.

Claim 8

An automatic vehicle-leveling system for maintaining a predetermined height relationship between the sprung and unsprung mass of a vehicle comprising: fluid spring means pressurizable to correct for changes in the height relationship between the sprung and the unsprung masses, a source of pressure including a compressor having an inlet and an outlet, an electric drive motor for operating said compressor, means for directly communicating the outlet of said compressor with said pressurizable fluid spring means including a height controller for sensing the relative height position between the sprung and unsprung mass, means for communicating the inlet of the said compressor with said fluid spring means including an enclosure having a single-pole, single-throw diaphragm operated switch therein, said height controller including means for preventing fluid flow either to or from said fluid spring means when a desired predetermined height relationship exists between the sprung and unsprung mass, said hEight controller further including means for communicating said fluid spring means with said enclosure when a predetermined static load is removed from the sprung mass, said pressure switch opening and closing at a predetermined fixed pressure point, a relay switch having a coil, first circuit means including said pressure switch for energizing said coil to operate said relay switch, second circuit means responsive to energization of said coil and operation of said relay switch to complete an energization circuit for said electric motor for pumping down said fluid spring means to compensate for reduced static loading thereon, and means responsive to opening of said pressure switch following a predetermined pumpdown to initiate a time delay period wherein said second circuit means is maintained conditioned to energize said electric motor until the pressure in said enclosure is reduced below the pressure required to open said single-pole, single-throw switch thereby to maintain said single-pole, single-throw switch biased against road movements of the vehicle, said second circuit means including means to remove an electric load from said pressure switch thereby allowing it to open without arcing following said predetermined pumpdown.

Claim 9

An automatic vehicle-leveling system for maintaining a predetermined height relationship between the sprung and unsprung mass of a vehicle comprising: fluid spring means pressurizable to correct for changes in the height relationship between the sprung and the unsprung masses, a source of pressure including a compressor having an inlet and an outlet, an electric drive motor for operating said compressor, means for directly communicating the outlet of said compressor with said pressurizable fluid spring means including a height controller for sensing the relative height position between the sprung and unsprung mass, means for communicating the inlet of the said compressor with said fluid spring means including an enclosure having a single-pole, single-throw diaphragm operated switch therein, said height controller including means for preventing fluid flow either to or from said fluid spring means when a desired predetermined height relationship exists between the sprung and unsprung mass, said hEight controller further including means for communicating said fluid spring means with said enclosure when a predetermined static load is removed from the sprung mass, said pressure switch opening and closing at a predetermined fixed pressure point, a relay switch having a coil, first circuit means including said pressure switch for energizing said coil to operate said relay switch, second circuit means responsive to energization of said coil and operation of said relay switch to complete an energization circuit for said electric motor for pumping down said fluid spring means to compensate for reduced static loading thereon, and means responsive to opening of said pressure switch following a predetermined pumpdown to initiate a time delay period wherein said second circuit means is maintained conditioned to energize said electric motor until the pressure in said enclosure is reduced below the pressure required to open said single-pole, single-throw switch thereby to maintain said single-pole, single-throw switch biased against road movements of the vehicle, said second circuit means including means to remove an electric load from said pressure switch thereby allowing it to open without arcing following said predetermined pumpdown.

Claim 10

An automatic vehicle-leveling system for maintaining a predetermined height relationship between the sprung and unsprung mass of a vehicle comprising fluid spring means pressurizable to correct for changes in the static loading on the sprung mass of the vehicle, means including a compressor having an inlet and an outlet for defining a pressure source for the fluid spring means, an electric motor for driving said compressor means for communicating the inlet of said compressor with said fluid spring means, first circuit means including a pressure-sensitive switch means responsive to the pressure level in said fluid spring means responsive to the pressure level in said fluid spring means to energize said compressor for causing it to pump down said fluid spring means so as to correct for removal of static load from the sprung mass of the vehicle, second circuit means for maintaining said motor energized during pumpdown, and third circuit means operative when said pressure switch senses a predetermined pressure to maintain said compressor energized for a predetermined delay period to reduce the level of pressure on said pressure switch means below said predetermined pressure, said pressure switch including means conditioned by said level of pressure below said predetermined pressure to prevent operation of said pressure switch means in response to road movements between the sprung and the unsprung mass of the vehicle.

Claim 11

An automatic vehicle-leveling system for maintaining a predetermined height relationship between the sprung and unsprung mass of a vehicle comprising fluid spring means pressurizable to correct for changes in the static loading on the sprung mass of the vehicle, means including a compressor having an inlet and an outlet for defining a pressure source for the fluid spring means, an electric motor for driving said compressor means for communicating the inlet of said compressor with said fluid spring means, first circuit means including a pressure-sensitive switch means responsive to the pressure level in said fluid spring means responsive to the pressure level in said fluid spring means to energize said compressor for causing it to pump down said fluid spring means so as to correct for removal of static load from the sprung mass of the vehicle, second circuit means for maintaining said motor energized during pumpdown, and third circuit means operative when said pressure switch senses a predetermined pressure to maintain said compressor energized for a predetermined delay period to reduce the level of pressure on said pressure switch means below said predetermined pressure, said pressure switch including means conditioned by said level of pressure below said predetermined pressure to prevent operation of said pressure switch means in response to road movements between the sprung and the unsprung mass of the vehicle.