Active hydropneumatic suspension system

An active hydropneumatic suspension system for controlling the motion and or position of a mass having a first motion and supported relative to a movable reference having a second motion independent of the first motion and the arms being isolatable from the movable reference and subject to external force to produce a relative motion between the mass and movable reference in different frequency bands comprising:

• support means including a series arranged hydropneumatic spring for producing a predetermined force to support the mass, servopump and hydropneumatic accumulator for receiving fluid from said hydropneumatic spring to isolate the mass from the movable reference;
• a control system including detectors for sensing the first motion of the mass and the second motion of the movable reference and the relative motion of the mass and the movable reference and operative to control the velocity of the servopump to transfer fluid energy between the hydropneumatic spring and the accumulator by transferring equal and opposite flow of energy from said hydropneumatic spring to said hydropneumatic accumulator substantially equal to the flow of energy caused by motion of said movable reference to adjust the force supporting the mass so as to maintain the predetermined force of the hydropneumatic spring and to transmit substantially zero dynamic force to the mass by the second motion of the moveable reference thereby to increase to increase the isolation of the mass from the motion of the movable reference in one or more frequency bands and to improve the equilibration of the mass relative to the movable reference in one or more other frequency bands.

An active hydropneumatic suspension system for controlling the motion and/or position of a mass having a first motion and supported relative to a movable reference having a second motion independent of the first motion and the mass being isolatable from the movable reference and subject to external force to produce a relative motion between the mass and the movable reference is different frequency bands comprising:

• support means including a series arranged hydropneumatic spring for producing a predetermined force to support the mass, servopump and hydropneumatic accumulator for receiving fluid from said hydropneumatic spring to isolate the mass from the movable reference;
• said servopump having a fixed displacement and a variable velocity and the hydropneumatic accumulator varying in oil volume in accordance with the operation of said servopump for isolating and stabilizing the mass with respect to the movable reference;
• a control system including detectors for sensing the motion of the mass, of the movable reference and the relative motion of the mass and the movable reference and including means for controlling the velocity of the servopump to transfer fluid energy between the hydropneumatic spring and the hydropneumatic accumulator by transferring equal and opposite flow of energy from said hydropneumatic spring to said hydropneumatic accumulator substantially equal to the flow of energy caused by motion of said movable reference to adjust the force supporting the mass so as to maintain the predetermined force of the hydropneumatic spring and to transmit substantially zero dynamic force to the mass by the second motion of the movable reference thereby to increase to both the isolation of the mass from the second motion of the movable reference and the stabilization of the mass when subject to external force in one or more of the different frequency bands and to improve the equilibration of the mass relative to the reference in one or more other of the different frequency bands.

An active hydropneumatic suspension system for controlling the motion and/or position of a mass having a first motion and relative to a movable reference having a second motion independent of the first motion and the mass being isolatable from the movable reference and subject to external force to produce a relative motion between the mass and the movable reference in different frequency bands comprising:

• a hydropneumatic spring including means defining a volume of pressure gas acting on a volume of pressure fluid to resiliently support said mass relative to said movable reference with a predetermined force;
• a servopump including means defining a servomotor and a fixed displacement pump;
• a hydropneumatic accumulator including means defining a volume of pressure gas acting on a volume of pressure fluid to resiliently equilibrate said servopump;
• said servopump having a variable velocity and the hydropneumatic accumulator varying in oil volume in accordance with the operation of said servopump for isolating and stabilizing the mass with respect to the movable reference;
• said hydropneumatic spring, servopump and hydropneumatic accumulator series arranged and said servopump operative to transfer fluid energy between said hydropneumatic spring and said hydropneumatic accumulator in a direction and at a rate proportional to the velocity of said servopump;
• and
• a control system including detectors for sensing the first motion of the mass, the second motion of the movable reference and the relative motion of the mass relative to the movable reference and operative to control the velocity of the servopump by transferring equal and opposite flow of energy from said hydropneumatic spring to said hydropneumatic accumulator substantially equal to the flow of energy caused by motion of said movable reference to adjust the force supporting the mass so as to maintain the predetermined force of the hydropneumatic spring and to transmit substantially zero dynamic force to the mass by the second motion of the movable reference to maintain both the isolation of the mass from the motion of the movable reference and the stabilization of the mass when subject to external force in one or more of the different frequency bands and to maintain the equilibration of the mass relative to the movable reference in one or more other of the difference frequency bands.

An active hydropneumatic suspension system in a vehicle for controlling the motion and or position of the vehicle's sprung mass having a first motion relative to the motion of the unsprung mass having a second motion independent of the first motion and the mass being isolatable from the movable reference of a roadwheel and subject to external force comprising:

• a passive hydropneumatic suspension system constituting the sole spring support for the sprung mass, the passive hydropneumatic suspension system including a single acting hydraulic actuator with a volume of fluid to apply a vertical force to said vehicle, said force reacted through a roadwheel to ground and a first hydropneumatic accumulator including means defining a volume of pressure gas acting on a volume of pressure fluid, said volume of pressure fluid connected to the volume of pressure fluid in said single acting hydraulic actuator to resiliently support the sprung mass relative to the unsprung mass,
• a servopump including means defining a servomotor and a fixed displacement pump;
• a second hydropneumatic accumulator including means defining a volume of pressure gas acting on a volume of pressure fluid;
• equilibration means to direct the pressure of said second hydropneumatic accumulator to equilibrate said servopump;
• first and second fluid conduits series connecting said passive suspension system, servopump and said second hydropneumatic accumulator and said servopump operating to transfer fluid energy between said passive hydropneumatic suspension system and said second hydropneumatic accumulator in a direction and at a rate proportional to the velocity of said servopump for isolating and stabilizing the sprung mass with respect to the unsprung mass at high and low frequencies of movement between the sprung mass and the unsprung mass;
• and
• a control system including detectors for sensing the motion of the sprung mass, the motion of the unsprung mass and the motion of the sprung mass relative to the unsprung mass and operative to control the velocity of said servopump to adjust the vertical force of the single acting hydraulic actuator supporting the sprung mass to improve the equilibration of the sprung mass relative to the unsprung mass at said low frequencies, to improve the isolation of the sprung mass relative to the motion of the unsprung mass at said high frequencies, and to improve the stabilization of the sprung mass when subject to external force in a band of the high and low frequencies.

An active hydropneumatic suspension system for controlling the motion and/or position of the sprung mass of a vehicle relative to the motion of the unsprung mass of roadwheels and subject to external force comprising:

• hydraulic device means;
• said hydraulic device means including a plurality of single acting hydraulic actuators supporting vehicle corners;
• a first hydropneumatic accumulator and a fluid damper;
• a first fluid conduit connecting said first accumulator and said fluid damper, said fluid damper operative to absorb fluid energy and convert it to heat energy as a function of the fluid flow rate through said damper;
• a mode selection valve;
• a second fluid conduit connecting said fluid damper and said mode selection valve, and interconnecting said fluid damper and said mode selection valve to that plurality of actuators which support one corner of the vehicle;
• said first accumulator, said fluid damper, and said actuators in combination defining a passive hydropneumatic suspension system having a first volume of pressure fluid supporting the vehicle relative to a plurality of roadwheels;
• a servopump;
• a third fluid conduit connecting said mode selection valve and said servopump;
• a second hydropneumatic accumulator having a second volume of pressure fluid to equilibrate said servopump;
• a fourth fluid conduit connecting said servopump and said second hydropneumatic accumulator;
• electrical means defining a power supply and a control system and said servopump operative when said mode selection valve interconnects said second fluid conduit and said third fluid conduit to transfer fluid energy between said passive suspension system and said second hydropneumatic accumulator, through said second conduit, said mode selection valve, said third conduit, and said fourth conduit at a rate and in a direction proportional to the velocity of said servopump;
• said power supply operative to provide electrical energy required for the operation of said control system, and said control system including means responsive to sensed operating conditions to control the velocity of said servopump to actively control the rate of change of position of said vehicle relative to said plurality roadwheels at low frequencies and to actively control the rate of change of force acting on said vehicle at higher frequencies.