Note: Descriptions are shown in the official language in which they were submitted.
202 1 332
REVFRSE INSTALLATION TYPE YARIABLE DAMPING FO~CE SHOCK
ABSORBER YARIABLE OF DAMPING CHARACTERISTICS BOTH FOR
BOUNDING AND REBOUNDING STROKE MOTIONS
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates generally to a
variable damping force shock absorber for an automotive
vehicle. More specifically, the invention relates to a
reverse installation type shock absorber designed to be
connected to a suspension member, such as suspension arm,
suspension link or so forth, at the lower end of a piston
rod and for variation of damping characteristics depending
upon piston stroke.
Description of the Back~round Art
Such reverse installation type shock absorber has
been disclosed in Japanese Patent First (unexamined)
Publication No. 58-97334, for- e~ample. The shown shock
absorber is designed for installation between a vehicular
body and a suspension member which rotatably supports a
vehicular wheel, in reversed manner to the usual shock
absorber. The shock absorber includes a cylinder tube, a
piston thrustingly or slidingly disposed within the internal
space of the cylinder tube, and a strut tube thrustingly and
slidingly supporting the cylinder tube. The top end of the
cylinder tube is connected to a vehicular body. On the
other hand, a piston rod extends downwardly from the bottom
of cylinder tube for connection with the suspension member.
Such prior proposed reverse installation type
shock absorber is defective in some aspects. For instance,
the prior proposed shock absorber is so designed as to
permit fluid flow from an upper fluid chamber to a lower
fluid chamber via a ~redetermined bounding stroke fluid path
and from the upper fluid chamber to an annular reservoir
- 2 ~ 202133~
chamber defined between the cylinder tube and the strut
tube. For this, when flow restriction magnitude for the
fluid from from the upper fluid chamber and to the lower
fluid chamber cannot be great enough to provide
satisfactorily high damping characteristics due to possibly
caused cavitation. As a result, variation range of the
damping characteristics is strictly limited. Since the
cylinder tube and the strut tube may be subiect force
transversely to the axis thereof. For this reason, the
cylinder tube may be required not only high precision level
in production for assuring smooth motion of the piston but
also sufficiently high strength for resisting against the
transverse force. This clearly cause high cost in
production.
SU~MARY OF THE INVENTION
Therefore, it is an object of the present
invention to provide a reverse installation type shock
absorber which can solve the drawbacks in the prior art as
set forth above.
Another objects of the present invention is to
provide a reverse installation type shock absorber which is
variable of damping characteristics both for bounding and
rebounding motion.
ZS
_ - 3 - 202 1 332
According to one aspect of the invention, a
reverse installed type variable damping force shock absorber
for an automotive suspension system, comprises:
an inner cylinder filled with a working fluid;
an outer cylinder coaxially housing therein the
inner cylinder and connected to a vehicular body for
vertical movement according to vertical motion of the
vehicular body, the outer cYIinder defining a space between
the inner cylinder, the space forming a reservoir chamber
and a communication chamber which is separated from the
reservoir chamber;
a piston disposed within t~e interior space of the
inner cylinder for defining therein first and second fluid
chambers; the piston being connected to a suspension member
rotatably supporting a vehicular wheel via a piston rod for
vertical movement with the vehicular wheel;
a first fluid path means for establishing fluid
communication between the first fluid chamber and the second
fluid chamber via the communication chamber;
a second fluid path means for establishing fluid
cammunication betwe,en the second fluid chamber and the
reservoir chamber via the communication chamber;
/
- 202 1 332
a first damping force generating means disposed in
the first path for generating damping force against bounding
mode relative displacement between the vehicular body and
the vehicular wheel; and
a second damping force generating means disposed
in the second fluid path means for generating damping force
against rebounding mode relative displacement between the
vehicular body and the vehicular wheel.
Preferably, the shock absorber may further
comprise a third fluid path means for establishing fluid
communication between the first fluid chamber and the
reservoir chamber by passing the first and second fluid path
means, a first variable throttling means disposed in the
third fluid path means and externally operable for adjusting
flow restriction magnitude. Also, the shock absorber may
further comprise a fourth fluid path means for establishing
fluid communication between the first and second fluid
chambers, and a second variable throttling means disposed
in the fourth fluid path means and externally operable for
adjusting flow restriction magnitude.
The first and second flow restriction means may be
operative for providing different damping characteristics
for bounding and rebounding mode relative motions of the
vehicular body and the vehicular body. Each of the first
and second flow restriction means may be switchable between
harder damping mode and softer damping mode so that harder
damping characteristics is obtained for bounding mode
relative motion when damping characteristics for rebounding
mode motion is set in softer characteristics and vis-a-vis.
The flow restriction means are so cooperated as to further
establish softer damping characteristics both for bounding
and rebounding mode relative motions of the vehicular body
and the vehicular whe,el.
BRIEF DESCRIPTION OF TH~ DRAWINGS
_ 5 _ 2021332
The present invention will be understood more
fully from the detailed description given herebelow and from
the accompanying drawings of the preferred embodiments of
the invention, which, however, should not be taken to limit
the invention to the specific embodiment or embodiments, but
are for explanation and understanding only.
In the drawings:
Fig. 1 is a section of the preferred embodiment of
a reverse installation type shock absorber according to the
invention, which section is used for discussion of overview
of the shock absorber according to the invention;
Fig. 2 is an enlarged section of the major part of
the first embodiment of the shock absorber of Fig. 1, in
which is shown a piston and a bottom valve employed in the
first embodiment of the shock absorber;
Fig. 3 is an enlarged section of the major part of
the first embodiment of the shock absorber, in which is show
a top valve employed on the first embodiment of the shock
absorber of Fig. 2;
Fig. 4 is a further enlarged section taken along
line ~ - ~ of Fig. 3;
Fig. 5 is also further enlarged section taken
along line V - V of Fig. 3:
Fig. 6 is a diagrammatical illustration showing
fluid path formed in the preferred embodiment of the shock
absorber;
Fig. 7 is a diagrammatical illustration showing a
modified fluid path to be applicable for the preferred
embodiment of the shock absorber of Fig. 2;
Fig. 8 is a section showing a modified
construction of the top valve to be employed for
establishing the fluid flow path of Fig. 7;
Fig. 9 is,a section showing another embodiment of
a top valve assembly to be employed in the preferred
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embodiment of the variable damping force shock absorber
according to the invention;
Figs. 10 to 12 are cross section respectively
taken along X - X , X I - X I and X ~ - X ~ of Fig. 9;
Figs. 13 and 14 are chart showing damping
characteristics relative to the bounding and rebounding
motions at various mode in the shock absorber employing the
top valve of Fig. 9;
Fig. 15 is a section showing a modification of the
top valve assembly of Fig. 9;
Figs. 16 to 18 are cross section respectively
taken along X - X , X I - X I and X ~ - X ~ showing
modification of the top valve assembly of Fig. 9;
Figs. 19, 20 and 21 are chart showing damping
characteristics relative to the bounding and rebounding
motions at various mode in the shock absorber employing the
top valve of Fig. 9;
Figs. 22 to 24 are cross section respectively
taken along X - X , X I - X I and X ~ - X ~ showing
another modification of the top valve assembly of Fig. 9;
and
Figs. 25 and 29 are chart showing damping
characteristics relative to the bounding and rebounding
motions at various mode in the shock absorber employing the
top valve of Fig. 9.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to the drawings, particularly to
Fig. 1, the preferred embodiment of a shock absorber,
according to the present invention, is designed for reverse
installation by connecting the lower end of a piston rod 22
to a knuckle spindle 10 and the top end of an outer tube 24
to a vehicular body (not shown). The shock absorber
includes a cylinder tube 26 which is generally formed into
upper and lower end opened cylindrical configuration. A
~ 7 ~ 232133~
bottom fitting guide assembly 30 is fitted onto the bottom
end opening of the cylinder tube 26. On the other hand, a
top valve assembly 40 is fitted onto the top end opening of
the cylinder tube 26. The cylinder tube 26 thus formed is
filled with a working fluid and is coaxially disposed in the
interior space of the outer tube 24. On the other hand, the
outer tube 24 is coaxially arranged with a strut tube 28.
A piston assembly 50 is thrustingly and slidingly
disposed within the interior space of the cylinder tube 26
for separating into an upper fluid chamber 262 and a lower
fluid chamber 264. The piston assembly 50 is rigidly fitted
onto the upper end of the piston rod 22 for movement
therewith according to movement of the knuckle spindle 10
relative to the vehicular body. The piston rod 22 extends
downwardly through the bottom valve assembly 30 and
connected to the knuckle spindle On the other hand, the top
valve assembly 40 is connected to the lower end of a
cylindrical support 60 which is, i~ turn, rigidly connected
to an actuator casing 62. With the shown construction, the
cylinder tube 26 with the top valve assembly 40 and the
bottom fitting guide assembly 30 are movable with the outer
tube 24 according to vertical movement of the vehicular body
relative to the knuckle spindle 10. In order to assist
thrusting movement of the outer tube 24 relative to the
strut tube 28 which is fixed to the knuckle spindle 10,
upper and lower plane bearings 202 and 204 are provided
between the inner periphery of the strut tube 28 and the
outer tube 24.
As can be seen from ~ig. 1, the top valve assembly
40 and the bottom fitting guide assembly 30 have seal rings
402 and 302 which establish sealing contact with the inner
periphery of the outer tube 24-for defining therein enclosed
spaces. An annular ,lower reservoir chamber 266 is defined
between the cylinder tube 26 and the outer cylinder 24.
- 8 - 202i332
Both axial ends of the lower fluid reservoir chamber 266 are
sealingly closed by the seal rings 402 and 302. On the
other hand, an upper fluid reservoir chamber 268is defined
above the upper end of the cylinder tube 26. The upper
fluid reservoir chamber 268 is separated from the lower
fluid reservoir chamber 266 by the upper seal ring 402. As
can be seen, the upper fluid reservoir chamber 268 defines
non-separated liquidous fluid chamber 2682 and gaseous fluid
chamber 2684 which encloses a pressure medium gas, such as
air. Since the pressure medium gas in the gaseous fluid
chamber 2684 is enclosed therein, the upper fluid reservoir
chamber 268 may have pressure accumulating capacity.
As will be discussed later, the lower fluid
reservoir chamber 266 is in fluid communication with the
lower fluid chamber 264 via a fluid path defined through the
bottom valve assembly 30. Similarly, the upper fluid
reservoir chamber 268 is in fluid communication with the
upper fluid chamber 262 via a fluid path defined through the
top valve assembly 40. The fluid path in the top valve
assembly 40 is variable of flow restriction magnitude for
the fluid flow therethrouh by means of a rotary valve 404
which is drivingly connected to an electrically operable
actuator 64 housed within the actuator housing 62 via an
actuator rod 66 extending through the cylindrical support
60. On the other hand, the upper and lower fluid chambers
262 and 264 are in fluid communication with the other via a
fluid path defined through the piston assembly 50.
As seen from Fig. 1, the strut tube 28 is fixed to
the knuckle spindle 10. An end fitting 282 with a bumper
rubber 284 is secured onto the bottom end of the strut tube
28. The lower end of the piston rod 22 is rigidly connected
to the end fitting 282 by means-of a fastening nut 222.
As shown in Fig. 2, the bottom fitting guide
assembly 30 generally comprises an essentially disc shaped
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guide body 302 defining a center opening 304 therethrough,
which center opening receives the piston rod 22. A seal
assembly 306 having an essentially ring shaped retainer 308
and an elastic seal ring 310 are fitted to the lower end of
the guide body 302. The seal ring 310 sealingly contacts
with the outer periphery of the piston rod 22 for
establishing liquid tight seal. For completing liquid tight
seal at the seal ring 310, a pressure reduction seal 312 is
provided on the inner periphery of the center opening 304.
The bottom fitting guide assembly 30 also provided with a
stopper rubber 314 for protecting the guide body 302 from
colliding with the piston assembly 40 during piston
rebounding stroke.
The guide body 302 of the bottom fitting guide
assembly 30 is formed with a fluid path groove 316. The
fluid path groove 316 opens to the lower fluid chamber 264
at one end and to the annular lower fluid reservoir chamber
266 at the other end. Therefore,~the lower fluid chamber
264 and the lower fluid reservoir chamber 266 are in fluid
communication via the fluid path groove 316. The path area
of the fluid path groove 316 is set small enough to restrict
fluid flow therethrough and thus to serve as a fixed
orifice.
On the other hand, the piston assembly 50 includes
a piston body 502, upper and lower disc valves 504 and 506,
washers 508 and 510, and stopper rings 512 and 514. The
components listed hereabove are assembled on the upper end
of the piston rod 22 and fastened thereon by means of a
fastening nut 516.
The piston body 502 defines axially extending
fluid path openings 518 and 520 which are oriented at
radially offset positions to-each other. The fluid path
opening 518 orient,ed at radially inner position will be
hereafter referred to as "inner fluid path opening" and the
202 1 332
-- 10 --
other will be hereafter referred to as "outer fluid path
opening ". The inner fluid path opening 518 opens to inner
annular grooves 522 and 524 respectively defined on the
upper and lower surfaces of the piston body 502. On the
other hand, the lower end of the outer fluid path opening
520 opens to an outer annular groove 526 defined on the
lower surface of the piston body. On the other hand, the
upper end of the outer fluid path opening 520 directly opens
to the upper fluid chamber 262.
The upper disc valve 504 is designed to be
resiliently seated onto inner and outer lands 528 and 530.
The upper disc valve 504 is designed for resi lient
deformation depending upon the pressure difference between
the upper fluid chamber 262 and the inner annular groove 522
for forming a variable path area orifice for permitting
fluid flow from the lower fluid chamber 264 to the upper
fluid chamber 262. On the other hand, the lower disc valve
506 is designed to be resiliently seated onto lands 532, 534
and 536 for resilient deformation depending upon the
pressure difference between the outer annular groove 526 and
the lower fluid chamber 264 for forming variable path area
orifice between the valve seat surface of the land 536 and
the mating surface of the lower disc valve 504. The lower
disc valve 506 is formed of a through opening (not clearly
shown) for permitting the working fluid in the lower fluid
chamber 264 to flow into the inner annular groove 524 during
piston rebounding stroke for establishing fluid flow from
the lower fluid chamber 264 to the upper fluid chamber 262.
As can be appreciated from the discussion
hereabove, the inner fluid path opening 518 serves for
establishing fluid path for fluid flow from the lower fluid
chamber 264 to the upper fluid chamber 262. Therefore, the
upper disc valve 50,4 thus serves for generating damping
force against the piston rebounding motion. Similarly, the
202 1 332
outer fluid path opening 520 serves for establishing fluid
communication from the upper fluid chamber 262 to the lower
fluid chamber 264 in piston bounding stroke. Therefore, the
lower disc valve 506 serves for generating damping force for
piston bounding stroke. Both of the variable path area
orifices defined by the upper and lower disc valves and the
associated lands are provided piston stroke dependency in
varying the fluid flow restriction magnitude and thus vary
damping characteristics. In general, the variation of
damping force is proportional to square of the piston
stroke.
As shown in Fig. 3, the top valve assembly 40
generally comprises upper and lower valve bodies 406 and
408, a retainer 410, a washer 412, a first damping valve
414, a first check valve 416, a washer 418, a retainer 420,
a washer 422, a second damping valve 424, a second check
valve 426, a washer 428 and a retainer 430. The components
listed hereabove are assembled to ~he lower end portion of
the cylindrical support 60 and rigidly secured thereonto by
means of a fastening nut 432. The upper and lower valve
bodies 406 and 408 are assembled to each other for defining
therein an internal chamber 434.
The upper valve body 406 is formed with an annular
groove 436 defined between lands 438 and 440 on the upper
surface thereof, and inner and outer annular grooves 442 and
444 defined between lands 446, 448 and 450 on the lower
surface of the upper valve body 406. An inner axially
extending opening 452 extends between the annular grooves
436 and 442 for fluid communication therewith. A first
skewed opening 454 has upper end directly opening to the
upper fluid reservoir chamber 268 and the lower end opening
to the outer annular groove 444. Similarly, the lower valve
body 408 is formed, with an annular groove 458 defined
between lands 460 and 462 on the upper surface thereof, and
202 1 332
- 12 -
inner and outer annular grooves 464 and 466 defined between
lands 468, 470 and 472 on the lower surface of the upper
valve body 406. An inner axially extending opening 474
extends between the annular grooves 458 and 464 for fluid
communication therewith. A second skewed opening 476 has
upper end directly opening to the upper fluid reservoir
chamber 268 and the lower end opening to the outer annular
groove 468. A third skewed opening 478 is formed through
the lower valve body 408, which has upper end directly
opening to the internal chamber 434 and the lower fluid
reservoir chamber 266.
The first damping valves 414 is provided mating
with the upper surface of the upper valve body 406 and
seated on the planer upper surfaces of the lands 438 and 440
for forming variable orifice therewith. The first check
valve 416 is provided in opposition with the lower surface
of the upper valve body for resiliently seating on the lower
planer surfaces of the lands 446; 448 and 450. The first
check valve 416 is formed with a through opening 4162 for
establishing fluid communication between the inner annular
groove 422 and the internal chamber 434. The first check
valve 416 is provided spring coefficient much smaller than
that of the first damping valve 414 so that the first check
valve may merely serve for establishing one-way fluid flow
from the upper fluid reservoir 268 to the internal chamber
434 of the top valve assembly 40. The second damping valves
424 is provided mating with the upper surface of the lower
valve body 408 and seated on the planer upper surfaces of
the lands 460 and 462 for forming variable orifice
therewith. The second check valve 426 is provided in
opposition with the lower surface of the upper valve body
for resiliently seating on the lower planer surfaces of the
lands 468, 470 and ,472. The second check valve 426 is
formed with a through opening 4164 for establishing fluid
- - 202 1 332
- 13 ~
communication between the inner annular groove 464 and the
annular groove 458. The second check valve 426 is provided
spring coefficient much smaller than that of the first
damping valve 414 so that the second check valve may merely
serve for establishing one-way fluid flow from the upper
fluid reservoir 268 to the upper f`luid chamber 262.
~ n the other hand, the cylindrical support 60
defines an axially opening 68. The rotary valve 404 is
rotatably disposed within the lower end portion of the
axially extending opening 68. The rotary valve 404 is
formed into essentially cylindrical configuration with
closed top , at which the rotary valve is rigidly connected
to the lower end of the actuation rod 66. An internal space
480 of the rotary valve 404 communicates with the upper
fluid chamber 262 via the lower end portion of the axially
extending opening 68. The rotary valve 404 are formed with
two pairs of radially extending openings 482 and 484 which
are oriented to axially offset positions to each other. The
upper pair of the radially extending openings 482 are
oriented at higher elevation than the upper end of the top
valve assembly 40. At the axial position corresponding to
that of the upper pair of radially extending openings 482, a
radial path opening 602 is formed through the peripheral
wall of the cylindrical support 60. The outer end of the
radial path opening 602 opens into the liquidous fluid
chamber 2682 of the upper fluid reservoir chamber 268.
Similarly, the lower pair of the radially extending openings
484 are oriented at lower elevation than the upper end of
the top valve assembly 40. At the axial position
corresponding to that of the lower pair of radially
extending openings 484, a radial path opening 604 is formed
through the peripheral wall of the cylindrical support 60.
The radial path open,ing 604 is in fluid communication with
an axially extending groove 486 which is, in turn, in fluid
202 1 332
-- 14 --
communication with the annular groove 436 of the upper valve
body 406. Therefore, the outer end of the radial path
opening 604 is in fluid communication with the annular
groove 436.
Thrust bushings 488 and 490 are provided at both
axial ends of the rotary valve 404 for facilitating smooth
rotation of thereof. Above the upper thrust bushing 488, a
seal ring 492 is provided for establishing liquid tight
seal.
As shown in Figs. 4 and 5, the pairs of the
radially extending openings 482 and 484 are provided
symmetrically with respect to the center axis. Therefore,
according to the angular position of the rotary valve 404,
the radially extending openings 482 and 484 are selectively
aligned and off-aligned with the radial path openings 602
and 604 for establishing and blocking fluid communication
therethrough. Typically, the rotary valve 404 is driven for
90 so as to place the axes of~the radially extending
openings 482 and 484 in alignment with the axes of the
radial path openings 602 and 604 at a SOFT mode position for
permitting fluid flow therethrough and in perpendicular to
the axes of the radial path openings at a HARD mode position
for blocking fluid communication therethrough.
The operation of the aforementioned shock absorber
in each of bounding mode and rebounding mode of vibration
will be discussed herebelow in order to facilitate better
understanding of the shown embodiment. In order to simplify
the discussion, reference is made to Fig. 6, in which is
explanatorily illustrated schematic diagram showing fluid
flow path to be established in the shown shock absorber.
BOUNDIN~ STROKE
In the bounding stroke, the piston assembly 50
shifts upwardly rel,ative to the cylinder tube 26 or the
outer tube 24 with the cylinder tube 26 shifts downwardly
2021 332
- 15 -
relative to the piston assembly 50. During this bounding
mode motion, the volume of the upper fluid chamber 262 is
compressed and the volume of the lower fluid chamber 264 is
expanded. Therefore, pressure balance between the lower
fluid chamber 264 and the lower fluid reservoir chamber 266
is destroyed to generate fluid flow from the lower fluid
reservoir chamber to the lower fluid chamber as shown by
arrow B1. The fluid flow rate from the lower fluid
reservoir chamber 266 to the lower fluid chamber 264 is
restricted by the limited fluid path area in the fluid path
groove 316. At the same time, the fluid pressure balance
between the upper and lower fluid chambers 262 and 264 is
also destroyed to cause fluid flow from the upper fluid
chamber to the lower fluid chamber across the piston
assembly 50. The higher pressure working fluid in the upper
fluid chamber 262 flows the outer annular groove 526 via the
outer fluid path opening 520. The fluid pressure in the
annular groove 526 causes deformation of the lower disc
valve 506 for forming the variable path area orifice to
permit the fluid flow therethrough, as shown by arrow ~2 of
Fig. 6. At the same time, the increased fluid pressure in
the upper fluid chamber 262 flows into the internal chamber
480 of the rotary valve 404 via the axial opening 68 of the
cylindrical support 60. If the rotary valve 404 is placed
at the angular position as illustrated, the limited flow
rate of fluid flow is permitted to flow into the upper fluid
reservoir 268 via the radially extending opening 482 and the
radial path opening 602, as shown by arrow ~3 in Fig. 6.
Further more, the fluid pressure entering into the annular
groove 458 via the communication opening 4262, the inner
annular groove 464 and the axially extending opening 474,
acts on the second damping valve 424 for causing deformation
to form the variab,le path area orifice for fluid flow
therethrough. Then, the pressurized fluid flowing into
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- 16 -
the internal chamber 434 through the variable path area
orifice formed by deformation of the second damping valve
424 flows into the lower fluid reservoir chamber 266 via the
third sorrowed opening 478, as shown by arrow B4. In
addition, part of the pressurized fluid in the intermediate
chamber 434 flows into the internal chamber 480 via the
communication opening 4162, the axially extending opening
452, thè annular groove 436, the axial groove 486, the
radial path opening 604 and the radially extending opening
484, as shown by arrow B5.
REBOUNDING STROKE
In the rebounding motion, the piston assembly 50
shifts downwardly relative to the cylinder tube 26, or in
the alternative, the outer tube 24 with the cylinder tube 26
shifts upwardly relative to the piston assembly, with
causing compression of volume in the lower fluid chamber
264. In this case, the higher pressure working fluid in the
lower fluid chamber 264 flows into ~the lower fluid reservoir
chamber 266 via the fluid path groove 316, as shown by arrow
Rl in Fig. 6. At the same time, the higher pressure working
fluid flows into the annular groove 522 via the inner
annular groove 524 and the inner fluid path opening 518.
The pressurized fluid in the annular groove 522 is active on
the upper disc valve 504 for causing deformation thereof to
form the variable path area orifice for fluid flow
therethrough, as shown by arrow R2. On the other hand, the
fluid pressure in the upper fluid chamber 262 decreases
according to expansion of the volume thereof. As a result,
the pressure balance between the upper and lower fluid
chambers 268 and 266 and the upper fluid chamber 262 is
destroyed. Therefore, the working fluid in the upper fluid
reservoir chamber 268 flows into the upper fluid chamber 262
via the radial pat,h opening 602, the radially extending
opening 482, the internal chamber 480 and the axial opening
- 17-221332
68, as shown by arrow R3. Furthermore, the working fluid in
the lower fluid reservoir chamber 266 flows into the
internal chamber 434 via the third skewed path 478. Then,
the fluid in the intermediate chamber 434 flows into the
internal chamber 480 via the communication opening 4162, the
annular groove 442, the axial opening 440, the annular
groove 436, the axial groove 486, the radial path opening
604 and the radially extending opening 484, as shown by
arrow R4. Furthermore, the pressurized fluid in the
intermediate chamber 434 is active on the first damping
valve 414 to cause deformation for forming the fluid path as
illustrated by arrow R5.
As will be appreciated herefrom, the first and
second damping valves 414 and 424 serve as principle element
for generating damping force in response to bounding and
rebounding mode of vibration. Namely, the first damping
valve 414 in the route R5 is active for generading damping
force during rebounding mode of vibration. On the other
hand, the second damping valve 424 in the route B4 is active
for bounding stroke of vibration. Therefore, the damping
characteristics of the first and second damping v~alves 414
and 424 are variable depending on the angular position of
the rotary valve 404. Namely, when the rotary valve 404 is
placed in a angular position for aligning the radially
extending openings 482 and 484 with the radial path openings
602 and 604, magnitude of damping force to be generated by
the first and second damping valves 414 and 416 becomes
small for providing softer damping characteristics. In
contrast to this, when the rotary valve 404 is placed in a
angular position for off-aligning the radially extending
openings 482 and 484 with the radial path openings 602 and
604, magnitude of damping force to be generated by the first
and second damping Ivalves 414 and 416 becomes much greater
for providing harder damping characteristics.
202 1 332
-- 18 --
As can be seen herefrom, in ei ther mode of
vibrations, fluid communication between the upper fluid
chamber 266 and the upper and lower fluid reservoir chambers
268 and 266 is established. With the shown construction,
HARD mode and SOFT mode damping characteristics as
illustrated by the solid line in Fig. 7. Variation
magnitude of damping force between the HARD and SOFT modes
becomes much greater than that in the prior art as
illustrated by the broken line in Fig. 7.
Fi g. 8 is a modi fication of the foregoi ng
embodiment of the shock absorber. In the shown
modification, the rotary valve 404 in the former embodiment
has been replaced with a thrusting valve 404' for axial
movement along the axis of the axial opening 68 of the
cylindrical support 60.
Figs. 9, 10, 11 and 12 show another embodiment of
the top valve assembly to be employed in the shown
embodiment of the shock absorber ac-cording to the invention.
The shown embodiment will be discussed utilizing the common
reference numerals for the components essentially common to
the former embodiments.
The shown embodiment is typically differentiated
from the embodiment shown in Fig. 3 in the rotary valve
construction. Namely, in the shown embodiment, the lower
end of the rotary valve 404 is sealingly closed by an end
fitting 4042. Therefore, direct fluid communication between
the internal chamber 434 of the rota-ry valve 404 and the
upper fluid chamber 262 via the axial opening 68 of the
cylindrical support 60 is blocked. In place of this,
another pair of radially extending openings 494 are formed
through the rotary valve 404. The radially extending
openings 494 are oriented at lower elevation than the
radially extending ppening 484. The radially extending
opening 494 is designed to selectively communicate and block
202 1 332
-- 19 --
fluid communication between the internal chamber 434 and a
radial path openings 606 formed through the cylindrical
support 60. The radial path opening 606 are in fluid
communication with the annular groove 458 formed on the
upper surface of the lower valve body 408, via an axially
extending grooves 496.
With the shown embodiment of the top valve
assembly, the radially extending openings 494 and the radial
path opening 606 cooperate to form another fixed orifice as
aligned to each other. In the shown embodiment, the
radially extending openings 4~4 are provided angular offset
from the angular orientation of the of the radially
extending openings 482 and 484 as shown in Figs. 10, 11 and
12.
In the shown embodiment, the radially extending
openings 484 and 494 are aligned in alternative fashion so
that when one of the pairs of openings 484 and 494 are
aligned with the corresponding rad;al path openings 604 and
606, the other pair are placed off-alignment from the
corresponding radial path openings. In the show
embodiment, the angular offset of the radially extending
openings 494 with respect to the radially extending opening
484 is set at approximately 45 . With the shown
embodiment, HARD and SOFT mode selection becomes alternative
as illustrated by Figs. 13 and 14.
Similar adjustment of the damping modes can be
down by the thrusting valve 404', as shown in Fig. 15. In
case of the thrusting valve 404' of Fig. 15, it becomes
possible to vary flow restriction magnitude by adjusting
overlapping magnitude between the radially extending
openings 482, 484 and 494 and the radial path openings 602,
604 and 606.
Though the,lforegoing embodiments are directed to
two way mode, i.e. HARD and SOFT modes, adjustments of the
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202 1 332
- 20 -
damping characteristics of the shock absorber, it may be
possible to provide capability of more than two modes.
Namely, in the example of Figs.16, 17 and 18, respective two
pairs of radially extending openings 4842, 4844 and 4942 and
4944 are provided. respective pairs of radially extending
openings 4844 and 4944 are provided angular shift from the
radially extending orifices 4842 and 4942 in a magnitude of
60 . With the shown arrangement of the radially extending
openings of Figs.16, 17 and 18, three way variable damping
characteristics as shown in Figs. 19, 20 and 21 can be
obtained. On the other hand, in the example of Figs. 22, 23
and 24, respective three pairs of radially extending
openings 4822, 4824, 4826, 4842, 4844, 4846 and 4942, 4944,
4946 are provided. In the shown construction, the pairs of
radially extending openings 4822, 4824 and 4826 are
respectively aligned on radial axes a, r and ~ .
Similarly, the radially extending openings 4842, 4844 and
4846 are respectively aligned on r~dial axes a, ~ and ~ .
Also, the radially extending openings 4942, 4944 and 4946
are respectively aligned on radial axes a , ~ and r . The
radial axes a, ~, r, ~ and ~ are respectively provided
angular shift for 36 . With the shown arrangement of
radially extending openings of Figs. 22, 23 and 24, five way
different damping modes can be established as shown in Figs.
25, 26, 27, 28 and 29. Namely, in the shown position in
Figs. 22, 23 and 24, the radially extending openings 4822,
4842 and 4942 are aligned on the axis a . The damping
characteristics of Fig. 25 is obtained. Similarly, at
respective angular positions aligning the radially extending
openings 4822, 4842 and 4942 on respective of axes ~ and r
. The radial axes a, ~, r , ~ and ~ , the damping
characteristics respectively illustrated in Figs. 26, 27, 28
and 29 can be obtain,ed.
As will be appreciated herefrom, the present
- 21 - 2021332
invention is successfully in providing capability of
adjustment of damping characteristics in both of bounding
and rebounding modes of vibration without causing
cavitation. Therefore, the present invention fulfills all
of the objects and advantages sought therefore.
While the present invention has been discussed in
terms of the preferred embodiments for practically
implementing the invention, the invention can be embodies in
various fashions. Therefore, the invention should be
appreciated to include all possible embodiments and
modifications thereof which are embodied without departing
from the principal of the invention as set out in the
appended claims.
