Suspension strut

Claim 2

In a suspension strut for fitting betwEen unsprung and sprung parts of a vehicle, an automatic level-control device comprising: first and second chambers each containing hydraulic fluid and a pneumatic spring; a pair of pumping elements connected respectively to the unsprung and sprung parts and comprising a pumping chamber communicating with the first chamber through an intake valve assembly and with the second chamber through a delivery valve assembly, and a plunger reciprocable in the pumping chamber to pump hydraulic fluid from the first chamber to the second chamber through said intake and delivery valve assemblies, the plunger having a cylindrical portion of larger diameter, a cylindrical portion of small diameter, and a tapered portion therebetween; a pair of annular compartments arranged end-to-end around the plunger and communicating respectively with the first chamber and with the second chamber, the said pair of compartments comprising a first annular compartment adjacent the pumping chamber and a second annular compartment adjacent the first annular compartment; and a pair of annular seals, comprising a first annular seal located between the pumping chamber and the first compartment, and a second annular seal located between the first compartment and the second compartment, each said annular seal having a diameter engaging tightly the larger diameter portion of the plunger, to seal said larger diameter portion, and to engage the tapered portion loosely to produce an escape of hydraulic fluid therebetween.

Claim 3

A suspension strut according to claim 1 acting as shock absorber and comprising: a cylinder having a cylinder head adjacent the first chamber and carrying said intake valve assembly; an annular partition carrying the first annular seal and the delivery valve assembly, the pumping chamber being contained within the cylinder between the cylinder head and the annular partition means supporting the second annular seal, the first annular compartment being disposed between the annular partition and said supporting means; an annular end closure provided with a third annular seal engaging said larger diameter portion of the plunger tightly, the second compartment being disposed between the second and third annular seals; a passage through the wall of the cylinder to connect the first compartment with the second chamber; and a shock absorber piston carried by the plunger and movable reciprocably in the pumping chamber.

Claim 4

A suspension strut according to claim 2, comprising a constricted orifice to connect the said channel with the first chamber.

Claim 5

A suspension strut according to claim 3, further comprising filter means to filter the hydraulic fluid flowing through the constricted orifice.

Claim 6

A suspension strut according to claim 2, further comprising an annular groove formed internally of the cylinder wall, an annular retaining ring fitted into the annular groove, and a spacer member engaging the annular closure so as to locate the said annular partition against the annular retaining ring.

Claim 7

A suspension strut according to claim 5, wherein an elastic coating covers at least a part of the inner surface of the said annular partition and of the surface thereof adjacent the said annular retaining ring, the coating being bonded to these surfaces, so as to provide the said first seal and to provide sealing between the said annular partition and the wall of the cylinder by squeezing the elastic coating between the annular partition, the retaining ring and the cylinder wall.

Claim 8

A suspension strut according to claim 6, wherein the said part of the inner surface of the annular partition includes an angular re-entrant portion and the part of the elastic coating which covers the said part of the inner surface in its relaxed state has a section in the form of two opposed triangles with a common base.

Claim 9

A suspension strut according to claim 2, wherein at least one channel passes through the said annular partition and includes an enlArgement where it opens into the said first annular compartment and in which the said delivery valve assembly comprises a ball which engages sealingly the enlargement, an annular spring passing inside a bore in the ball, and wherein retention means are provided to attach the annular spring to the annular partition so as to load the ball against the enlargement.

Claim 10

A suspension strut according to claim 8, wherein: the surface of the said annular partition which faces the first compartment includes a recessed sector in which the said enlargement is formed; an arcuate groove is formed in the said surfae externally of the recessed sector; the annular spring is fitted into the arcuate groove; and the retention means act at a position diametrically opposite to the recessed sector so as to hold the annular spring in the arcuate groove.

Claim 11

A suspension strut according to claim 8, wherein the spacer member constitutes a stop acting to restrict the lift of the ball.

Claim 12

A hydropneumatic suspension strut and shock absorber assembly comprising: a cylinder having a cylinder heat and defining a cylinder chamber containing hydraulic fluid; a shock absorber piston reciprocably mounted to slide in the cylinder and having damping valve-controlled passages therethrough for the hydraulic fluid flowing through said passages response to reciprocating of the piston; a piston rod having a cylindrical portion of larger diameter, a tapered portion and a cylindrical portion of smaller diameter having a free end carrying the shock absorber piston; a reservoir chamber adjacent the cylinder head containing hydraulic fluid and a pneumatic spring; a passage in the cylinder head incorporating an intake valve assembly for the intake of hydraulic fluid from said reservoir chamber into said cylinder chamber; an annular partition around the piston rod within the cylinder defining therein a first annular compartment and carrying a first annular seal having a diameter tightly engaging the larger diameter cylindrical portion of the piston rod sealing said larger diameter cylindrical portion and loosely engaging the tapered portion permitting the escape of hydraulic fluid between said tapered portion and said first annular seal; a passage through the annular partition incorporating a delivery valve assembly for the delivery of hydraulic fluid from the cylinder chamber to the first annular compartment; a hydropneumatic chamber containing hydraulic fluid and a pneumatic spring, and a passage connecting said hydropneumatuc chamber to the first compartment; end closure means for the cylinder defining a second annular compartment around the piston rod and carrying a second annular seal between said first and second annular compartments, and a third annular seal beyond said second compartment, said second annular seal having a diameter tightly engaging the larger diameter cylindrical portion of the piston rod sealing said larger diameter cylindrical portion and loosely engaging the tapered portion permitting the escape of hydraulic fluid between said tapered portion and said second annular seal, and said third annular seal being adapted to seal the piston rod tightly; and passage means connecting the second annular compartment to the reservoir chamber.

Claim 13

A hydropneumatic suspension strut and shock absorber assembly comprising: a cylinder having a cylinder heat and defining a cylinder chamber containing hydraulic fluid; a shock absorber piston reciprocably mounted to slide in the cylinder and having damping valve-controlled passages therethrough for the hydraulic fluid flowing through said passages response to reciprocating of the piston; a piston rod having a cylindrical portion of larger diameter, a tapered portion and a cylindrical portion of smaller diameter having a free end carrying the shock absorber piston; a reservoir chamber adjacent the cylinder head containing hydraulic fluid and a pneumatic spring; a passage in the cylinder head incorporating an intake valve assembly for the intake of hydraulic fluid from said reservoir chamber into said cylinder chamber; an annular partition around the piston rod within the cylinder defining therein a first annular compartment and carrying a first annular seal having a diameter tightly engaging the larger diameter cylindrical portion of the piston rod sealing said larger diameter cylindrical portion and loosely engaging the tapered portion permitting the escape of hydraulic fluid between said tapered portion and said first annular seal; a passage through the annular partition incorporating a delivery valve assembly for the delivery of hydraulic fluid from the cylinder chamber to the first annular compartment; a hydropneumatic chamber containing hydraulic fluid and a pneumatic spring, and a passage connecting said hydropneumatuc chamber to the first compartment; end closure means for the cylinder defining a second annular compartment around the piston rod and carrying a second annular seal between said first and second annular compartments, and a third annular seal beyond said second compartment, said second annular seal having a diameter tightly engaging the larger diameter cylindrical portion of the piston rod sealing said larger diameter cylindrical portion and loosely engaging the tapered portion permitting the escape of hydraulic fluid between said tapered portion and said second annular seal, and said third annular seal being adapted to seal the piston rod tightly; and passage means connecting the second annular compartment to the reservoir chamber.