Hydropneumatic type suspension unit of a motor vehicle suspension system

Claim 2

A suspension unit for a wheeled vehicle comprising a first cylinder connected to a body of said vehicle and having a first cylinder chamber filled with pressurized fluid and a cylinder head formed with inlet and outlet passageways, said inlet passageway communicating with a source of pressurized fluid for supplying said first cylinder chamber with pressurized fluid, a first axially slidable piston in said first cylinder chamber, a first piston rod projecting from said first piston and extending externally through one end of said first cylinder opposite to said cylinder head, first regulator means for selectively providing fluid communication between said first cylinder chamber and said inlet passageway and between said first cylinder chamber and said outlet passageway depending upon the fluid volume in said first cylinder chamber, said first regulator means comprising a free piston axially slidable in said first cylinder chamber between said cylinder head and said first piston, and spring means for urging said free piston to a balance and neutral position causing isolation of said first cylinder chamber from said inlet and outlet passageways, said first cylinder chamber arranged to communicate with said inlet passageway when said first cylinder is moved relative to said first piston in one direction tending to shorten said suspension unit and with said outlet passageway when said first cylinder is moved relative to said first piston in the opposite direction tending to lengthen said suspension unit, a second cylinder formed on said first piston rod in alignment with said first cylinder and having a second cylinder chamber filled with pressurized fluid, a sEcond piston axially slidable in the second cylinder chamber, a second piston rod projecting from said second piston and extending externally through one end of said second cylinder and mounted on a wheel supporting means of said vehicle, and second regulator means for regulating the amount of pressurized fluid in the second cylinder chamber to vary the length of said suspension unit and thus the height of the vehicle level.

Claim 3

A suspension unit as claimed in claim 1, further comprising a hydropneumatic spring unit having a casing which is divided by a flexible partition member into a gas chamber filled with gas under pressure and a fluid chamber communicating with said first cylinder chamber through a restrictor.

Claim 4

A suspension unit as claimed in claim 1, in which said first regulator means further comprises a first servo valve for controlling fluid communication between said inlet passageway and said first cylinder chamber, a second servo valve for controlling fluid communication between said outlet passageway and said first cylinder chamber, a first poppet valve cooperating with said free piston to open said first servo valve when said free piston is moved in said one direction, and a second poppet valve cooperating with said free piston to open said second servo valve when said free piston is moved in the opposite direction.

Claim 5

A suspension unit as claimed in claim 1, in which said spring means comprises a first spring for urging said free piston in said one direction, said first spring being provided between said first piston and said free piston, and a second spring for urging said free piston in the opposite direction, said second spring being provided between said cylinder head and said free piston.

Claim 6

A suspension unit as claimed in claim 1, in which said second piston rod is formed with an axial passage extending through said second piston rod through which pressurized fluid is fed formed a source of pressurized fluid into said second cylinder chamber.

Claim 7

A suspension unit as claimed in claim 1, in which said second regulator means comprises a solenoid valve arrangement having a first position to provide fluid communication between the second cylinder chamber and said source of pressurized fluid, a second position to permit exhaust of fluid from said second cylinder chamber and a neutral position to isolate said second cylinder chamber from said source of pressurized fluid while preventing exhaust of fluid therefrom.

Claim 8

A suspension unit as claimed in claim 6, further comprising a vehicle level detection circuit including a contact provided on a side wall of said second cylinder chamber and a plurality of axially spaced contacts provided on said second piston rod, said plurality of axially spaced contacts being arranged to engage in turn said contact on said wall of said second chamber when the vehicle reaches their corresponding predetermined vehicle levels.

Claim 9

A suspension unit as claimed in claim 7, further comprising a vehicle level selection circuit connected to said vehicle level detection circuit and said solenoid valve arrangement, said vehicle level selection circuit being operable to actuate said solenoid valve arrangement so as to contain in the second cylinder chamber the amount of pressurized fluid corresponding to a selected vehicle level.

Claim 10

A suspension unit as claimed in claim 1, further comprising a rebound dampener provided on said first piston to prevent said first piston from abutting on an end wall of said first cylinder.

Claim 11

A suspension unit for a wheeled vehicle comprising a cylinder connected to a body of said vehicle and having a first fluid chamber filled with pressurized fluid, a first piston axially slidable in said first fluid chamber, a first piston rod connected to said first piston and having formed therein a second fluid chamber filled with pressurized fluid, first vehicle level regulating means selectively providing communication between said first fluid chamber and a source of pressurized fluid and between said first fluid chamber and a reservoir in response to variation in the weight and/or load of said vehicle thereby maintaining the effective length of said suspension unit at a substantially constant value independently of the weight and/or load of said vehicle, a second piston axially slidable in said second fluid chamber, a second piston rod connected to said second piston and mounted on a wheel supporting means of said vehicle, and second vehicle level regulating means selectively providing communication between said second fluid chamber and a source of pressurized fluid and between said second fluid chamber and a reservoir thereby varying the effective length of said suspension unit.

Claim 12

A suspension unit for a wheeled vehicle comprising a cylinder connected to a body of said vehicle and having a first fluid chamber filled with pressurized fluid, a first piston axially slidable in said first fluid chamber, a first piston rod connected to said first piston and having formed therein a second fluid chamber filled with pressurized fluid, first vehicle level regulating means selectively providing communication between said first fluid chamber and a source of pressurized fluid and between said first fluid chamber and a reservoir in response to variation in the weight and/or load of said vehicle thereby maintaining the effective length of said suspension unit at a substantially constant value independently of the weight and/or load of said vehicle, a second piston axially slidable in said second fluid chamber, a second piston rod connected to said second piston and mounted on a wheel supporting means of said vehicle, and second vehicle level regulating means selectively providing communication between said second fluid chamber and a source of pressurized fluid and between said second fluid chamber and a reservoir thereby varying the effective length of said suspension unit.

Claim 13

A suspension unit for a wheeled vehicle comprising a first cylinder having a first fluid chamber filled with pressurized fluid and having formed at one end thereof a second cylinder which is in alignment with said first cylinder and which has a second fluid chamber filled with pressurized fluid, a first piston axially slidable in said first fluid chamber, a first piston rod connected to said first piston and mounted on a wheel supporting means of said vehicle, first vehicle level regulating means selectively providing communication between said first fluid chamber and a source of pressurized fluid and between said first fluid chamber and a reservoir in response to variation in the weight and/or load of said vehicle thereby maintaining the effective length of said suspension unit at a substantially constant value independently of the weight and/or load of said vehicle, a second piston axially slidable in said second fluid chamber, a second piston rod connected to said second piston and to a body of said vehicle, and second vehicle level regulating means selectively providing communication between said second fluid chamber and a source of pressurized fluid and between said second fluid chamber and a reservoir thereby varying the effective length of said suspension unit.

Claim 14

A suspension unit for a wheeled vehicle comprising a first cylinder having a first fluid chamber filled with pressurized fluid and having formed at one end thereof a second cylinder which is in alignment with said first cylinder and which has a second fluid chamber filled with pressurized fluid, a first piston axially slidable in said first fluid chamber, a first piston rod connected to said first piston and mounted on a wheel supporting means of said vehicle, first vehicle level regulating means selectively providing communication between said first fluid chamber and a source of pressurized fluid and between said first fluid chamber and a reservoir in response to variation in the weight and/or load of said vehicle thereby maintaining the effective length of said suspension unit at a substantially constant value independently of the weight and/or load of said vehicle, a second piston axially slidable in said second fluid chamber, a second piston rod connected to said second piston and to a body of said vehicle, and second vehicle level regulating means selectively providing communication between said second fluid chamber and a source of pressurized fluid and between said second fluid chamber and a reservoir thereby varying the effective length of said suspension unit.

Claim 15

A suspension unit for a wheeled vehicle comprising a first cylinder having a first cylinder chamber filled with pressurized fluid and a cylinder head formed with inlet and outlet passageways, said inlet passageway communicating with a source of pressurized fluid for supplying said first cylinder chamber with pressurized fluid, a first piston axially slidable in said first cylinder chamber, a first piston rod projecting from said first piston and extending externally through one end of said first cylinder opposite to said cylinder head and mounted on a wheel supporting means of said vehicle, first regulator means for selectively providing fluid communication between said first cylinder chamber and said inlet passageway and between said first cylinder chamber and said outlet passageway depending upon the fluid volume in said first cylinder chamber, said first regulator means comprising a free piston axially slidable in said first cylinder chamber between said cylinder head and said first piston, and spring means for urging said free piston to a balanced and neutral position causing isolation of said first cylinder chamber from said inlet and outlet passageways, said first cylinder chamber arranged to communicate with said inlet passageway when said first cylinder is moved relative to said first piston in one direction tending to shorten said suspension unit and with said outlet passageway when said first cylinder is moved relative to said first piston in the opposite direction tending to lengthen said suspension unit, a second cylinder formed on said cylinder head of said first cylinder in alignment with said first cylinder and having a second cylinder chamber filled with pressurized fluid, a second piston axially slidable in the second cylinder chamber, a second piston rod projecting from said second piston and extending externally through one end of said second cylinder and connected to a body structure of said vehicle, and second regulator means for regulating the amount of pressurized fluid in the second Cylinder chamber to vary the length of said suspension unit and thus the height of the vehicle level.

Claim 16

A suspension unit for a wheeled vehicle comprising a first cylinder having a first cylinder chamber filled with pressurized fluid and a cylinder head formed with inlet and outlet passageways, said inlet passageway communicating with a source of pressurized fluid for supplying said first cylinder chamber with pressurized fluid, a first piston axially slidable in said first cylinder chamber, a first piston rod projecting from said first piston and extending externally through one end of said first cylinder opposite to said cylinder head and mounted on a wheel supporting means of said vehicle, first regulator means for selectively providing fluid communication between said first cylinder chamber and said inlet passageway and between said first cylinder chamber and said outlet passageway depending upon the fluid volume in said first cylinder chamber, said first regulator means comprising a free piston axially slidable in said first cylinder chamber between said cylinder head and said first piston, and spring means for urging said free piston to a balanced and neutral position causing isolation of said first cylinder chamber from said inlet and outlet passageways, said first cylinder chamber arranged to communicate with said inlet passageway when said first cylinder is moved relative to said first piston in one direction tending to shorten said suspension unit and with said outlet passageway when said first cylinder is moved relative to said first piston in the opposite direction tending to lengthen said suspension unit, a second cylinder formed on said cylinder head of said first cylinder in alignment with said first cylinder and having a second cylinder chamber filled with pressurized fluid, a second piston axially slidable in the second cylinder chamber, a second piston rod projecting from said second piston and extending externally through one end of said second cylinder and connected to a body structure of said vehicle, and second regulator means for regulating the amount of pressurized fluid in the second Cylinder chamber to vary the length of said suspension unit and thus the height of the vehicle level.