Note : Les revendications sont présentées dans la langue officielle dans laquelle elles ont été soumises.
Claims
1. A suspension system for a wheeled vehicle having a body portion
comprising means for sensing lateral and longitudinal acceleration (18, 20, 22, 24,
26) of said body portion characterized in that,
a digital hydraulic actuator (42, 42A, 57, 200, 310, 450) supports said body
portion from each of said wheels (10, 12, 14, 16), each said actuator (42,
42A, 57, 200, 310, 450) including a plurality of different effective area
actuator sections (60, 62, 64, 68, 70, 72, 74, 208, 210, 212, 214, 314, 316,
318, 338, 340, 342, 344, 314A, 316A, 318A, 338A, 340A, 342A), a first
source of hydraulic fluid at a first pressure (PH), a second source of
hydraulic fluid at a second pressure PL, said second pressure (PL) being
significantly different from said first pressure (PH), valve means (30, 32, 34,
36, 52, 54, 56, 78, 80, 82, 84, 360, 362, 364, 366, 368, 370, 372, 472) for
selectively connecting either one or the other of said first source (PH) and
said second source (PL) to selected of said actuator sections (60, 62, 64, 68,
70, 72, 74, 208, 210, 212, 214, 314, 316, 318, 338, 340, 342, 344, 314A,
316A, 318A, 338A, 340A, 342A) thereby to vary the number of said
actuator sections (60, 62, 64, 68, 70, 72, 74, 208, 210, 212, 214, 314, 316,
318, 338, 340, 342, 344, 314A, 316A, 318A, 338A, 340A, 342A) and thereby
the amount of said effective area of each said actuator (42, 42A, 57, 200,
310, 450) subjected to said first (PH) and said second (PL) pressure sources
to selectively vary the force applied by each said actuator (42, 42A, 57,
200, 310, 450) independent of the extension of said actuator (42, 42A, 57,
200, 310, 450), computer means (28, 382) for controlling said valve means
(30, 32, 34, 36, 52, 54, 56, 78, 80, 82, 84, 360, 362, 364, 366, 368, 370, 372,
472) to adjust the number of said actuator sections (60, 62, 64, 64, 70, 72,
74, 208, 210, 212, 214, 314,316, 318, 338, 340, 342, 344, 314A, 316A, 318A,
338A, 340A, 342A) of each said digital hydraulic actuator (42, 42A, 57,
200, 310, 450) subjected to said first and said second pressures based on
anticipated forces at each said actuator (42, 42A, 57, 200, 310, 450) as
determined by said computer means (28, 382) based on conditions sensed
by said means for sensing lateral and longitudinal acceleration thereby to
maintain said body portion substantially stable.
2. A suspension system as defined in claim 1 further comprising means
to measure (104) the displacement of each said actuator (42, 42A, 57, 200, 310,
450) to provide a signal representing the displacement of each said actuator (42,
42A, 57, 200, 310, 450) to said computer means (28, 382) and said computer
means (28, 382) controlling said valve means (30, 32, 34, 36, 52, 54, 56, 78, 80, 82,
84, 360, 362, 364, 366, 368, 370, 372, 472) to tend to maintain said actuator (42,
42A, 57, 200, 310, 450) in a position wherein said each said actuator (42, 42A, 57,
200, 310, 450) has a preselected degree of extension.
3. A suspension system as defined in claim 2 wherein each said actuator
(42, 42A, 57, 200, 310, 450) is a double acting actuator.
4. A suspension system as defined m claims 1, 2 or 3 wherein hydraulic
actuator (42, 42A, 57, 200 310, 450) comprises a housing (202), a rotor (204)
extending through said housing (202), a plurality of axially extending radially
projecting circumferentially spaced lugs (216, 218, 200 222) on said housing (202)
and defining a plurality of circumferentially extending spaces (208, 210, 212, 214)
therebetween, a pair of circumferentially opposed surfaces (250, 254) on an
adjacent pair of said lugs (216, 218) defining opposite circumferentially spacedends of each of said spaces (208, 210, 212, 214), each of surfaces (250, 254) ofsaid pairs of opposed surfaces (250, 254) of an adjacent pair lugs (216, 218, 220,
222) having different areas, axially extending radially projecting spaced bosses(242, 244, 246) on said rotor (204), each said boss (242, 244, 246) being received
within a different one of said spaces (208, 210, 212, 214) and dividing its
respective said space (208, 210, 212, 214) into a pair of said actuator sections(208A, 208B, 210A, 210B, 212A, 212B) one on each side of said boss (242, 244,
246), each said boss (242, 244, 246) having each of its radial circumferentiallyspaced sides substantially the same area as its adjacent opposed surface of saidlug (216, 218, 220, 222) forming the adjacent circumferential end of said space in
which it is received, said lugs (216, 218, 220, 222) having end faces cooperating
with said rotor (204) and said bosses (242, 244, 246) having surfaces cooperating
with circumferentially extending surfaces of said spaces (208, 210, 212,214) to seal
one said actuator section (208A, 208B, 210A, 210B, 212A, 212B) of said pair of
sections (208A, 208B, 210A, 210B, 212A, 212B) in said space (208, 210, 212, 214)in which said boss (242, 244, 246) is received from the other of said pair of
actuator sections (208A, 208B, 210A, 210B, 212A, 212B), said rotor (204) being
rotatable mounted within said housing (202) so that each boss (242,244, 246) mayrotate within its respective space (208, 210, 212, 214)through a preselected angle
of rotation and said valve means (52, 54, 56, 78, 80, 82, 84) fluid under said first
(PH) or said second (PL) pressure into each of said actuator sections (208A, 208B,
210A, 210B, 212A, 212B).
5. A suspension system as defined in claims 1, 2 or 3 wherein said
digital hydraulic actuator (310, 450) comprises a fixed element (312, 312A), a
driven piston (330, 330A) cooperating with a first cylinder (386, 386A) formed by
said fixed element (312, 312A), said digital actuator (310, 319A) digitally adjusting
the pressure between said fixed element (312, 312A) and said driven piston (330,330A) tending to displace said driven piston (3307 330A) in said first cylinder
(386, 386A), a second cylinder (392, 392A), a hydraulic coupling (388, 388A)
hydraulically connecting said first cylinder (386, 386A) to said second cylinder,
said second cylinder (392, 392A) having a cross sectional area different from said
first cylinder (386, 386A), a working piston (390, 390A) in said second cylinder(392, 392A) adapted to apply a force determined by the ratio of the cross
sectional areas of said first (386, 386A) and second (392, 392A) cylinders.
6. A suspension system as defined in claims 1, 2 or 3 wherein said
digital hydraulic actuator (45) comprising a cylinder (386A), a body member
(312A) having a fixed element (312A) having a chamber (376A, 380A), said fixed
element (312A) cooperating with a piston (330A) in said cylinder (386A), said
fixed element (312A) said digital hydraulic actuator digitally adjusting the
pressure between said fixed element (312A) and said piston (330A), a second
piston (364) dividing said chamber (376A, 380A) into a high pressure chamber
(376A PH) and a low pressure reservoir (380, PL), means for urging said second
piston (364) toward said high pressure reservoir (376A, PH) to generate said
differential in pressure in hydraulic fluid filling said high (376A, PH) and said low
pressure reservoir (380A, PL), said valve means (472) set of valves (472) in said
body member (312A), a first passage means (470) through said body member
(312A) connecting each of said valves (472) to said high pressure (376A, PH)a
second passage means (522) in said body member connecting said low pressure
reservoir (380, PL) to each of said valves (472), individual passages (504, 506, 508,
510, 512, 514) through said body member (312A) connecting each of said actuator
sections (314A, 316A, 318A, 338A, 340A, 342A) with its respective valve (472) ofsaid set of valves (472).
7. A digital hydraulic actuator comprising a fixed member (312, 312A),
a driven member (330, 330A) cooperating with a first cylinder (386, 386A) formedby said fixed member (312, 312a) means to digitally vary the pressure acting
between said fixed member (312, 312A) and said driven member (330, 330A)
tending to displace said driven member (330, 330A) in said first cylinder (386,
386A), characterized in that;
a hydraulic coupling (388, 388A) hydraulically connects said first cylinder
(386, 386A) to said second cylinder (392, 392A), said second cylinder (392,
392A) having a cross sectional area different from said first cylinder (386,
386A), a working piston (390, 390A) in said second cylinder (392, 392A)
adapted to apply a force determined by the ratio of the cross sectional
areas of said first (386, 386A) and second (392, 392A) cylinders.
8. A digital hydraulic actuator as defined in claim 7 wherein said
means to digitally vary the pressure acting between said fixed member (312,
312A) and said driven piston (330, 330A) includes a first set of different crosssectional area piston cavities (314, 316, 318, 314A, 316A, 318A) and a first set of
different cross section area pistons (322, 324, 326, 322A, 324A, 326A) on said
fixed member (312, 312A), a second set of different cross sectional area pistons(332, 334, 336, 332A, 334A, 336A) and a second set of different cross sectional
area piston cavities (338, 340, 342, 344, 338A, 340A, 342A) on said driven piston
(330, 330A), each piston of said second set of pistons (332, 334, 336, 332A, 334A,
336A) being received within said one of said cavities of said first set of piston
cavities (314, 316, 318, 314A, 316A, 318A) and each cavity of said second set ofpiston cavities (338, 340, 342, 344, 338A, 340A, 342A) receiving a piston of said
first set of pistons (322, 324, 326, 322A, 324A, 326A), and means to selectivelyapply fluid (360, 362, 364, 366, 368, 370, 372, 472) under selected pressures (PH,
PL) to each cavity (314, 316, 318, 314A, 316A, 318A, 338, 340, 342, 344, 338A,
340A, 342A) of said first and said second sets of cavities.
9. A digital hydraulic actuator as defined in claim 8 wherein said
means to selectively apply fluid (360, 362, 364, 366, 368, 370, 372, 472) under
selected pressure applies one of a first (PH) or a second (PL) pressure to each of
said cavities (314, 316, 318, 314A, 316A, 318A, 338, 340, 342, 344, 338A, 340A,
342A), said first (PH) and second (PL) pressures being significantly different.
10. A digital hydraulic actuator as defined in claims 7, 8 or 9 said fixedmember has a chamber (376A, 380A, PH, PL), piston element (464) dividing said
chamber (376A, 380A, PH, PL) into a high pressure chamber (376A PH) and a low
pressure reservoir (380A, PL), means for urging (466) said piston (464) toward
said high pressure chamber (374A, PH) to generate a differential in pressure in
hydraulic fluid filling said high (374A, PH) and said low pressure (380A, PL)
reservoirs, set of valves (472) in said fixed member (312A), said set of valves
(472) including one valve (342) for each of said cavities (314A 316A, 318A, 338A,
340A, 342A), a first passage means (370) through said fixed member (312A)
connecting each of said valves (472) to said high pressure chamber (374A, PH),
a second passage means (522) in said fixed member (312A) connecting said low
pressure reservoir (380A, PL) to each of said valves (472), individual passages
through said fixed member (312A) correcting each of said cavities (314A, 316A,
318A, 338A, 340A, 342A) with its respective valve (472) of said set of valves
(472).
11. An actuator assembly as defined in claim 10 wherein said valves
(472) of said set of valves (472) are symmetrically positioned around the
longitudinal axis of said fixed member (312A).
12. An actuator assembly as defined in claim 11 further comprising
means for coupling (388A) said cylinder (386A) to a hydraulic actuator (392A)
to deliver hydraulic fluid under pressure from said cylinder (386A) to one side of
said hydraulic actuator (392A).
13. An assembly as defined in claim 12 wherein said chamber (376A,
380A, PH, PL) and said cylinder (386A) are at axial opposite ends of said fixed
member (312A).
14. An assembly as defined in claim 11, 12 or 13 wherein said first
passage means (370) includes a passage (370) extending substantially along the
longitudinal axis of said fixed member (312A) through a shaft (468) projecting
into said chamber (376A, 380A, PH, PL) and wherein said piston element (464)
surrounds and slides axially along said shaft (468) in sealed relationship thereto.