Vibration damper for a motor vehicle suspension

A motor vehicle suspension system for damping vibrations between, for example, the wheels of the motor vehicle and the body of the motor vehicle, can have a vibration damper unit with two fluid chambers therein and separated from one another by a piston unit. In addition, there can be a fluid bypass connecting the two chambers. A shut-off valve device can be disposed between two portions of the fluid connection to separate a high-pressure section and a low-pressure section, and the latter shut-off valve has a shutoff body which can be adjusted by an external control by means of a magnet armature and a magnet coil between a closed and an open position. The high pressure section empties into a central channel, and a first side of the shut-off valve body which is pressurized by the high pressure section can be elastically pressed against a shut-off valve seat by means of a compression spring, whereby the first side of the shut-off valve body is connected by means of an after-throttle to a second side of the shut-off valve body. Within the fluid connection there can be a segment which provides a pressure reduction by means of at least one throttle point in combination with a baffle device which is connected to the throttle point.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention generally relates to a vibration damper for a motor 
vehicle suspension system for damping vibrations between, for example, the 
wheels of the motor vehicle and the body of the motor vehicle. Such a 
vibration damper will generally have two fluid chambers separated from one 
another by a piston unit. In addition, there can be a fluid bypass 
connecting the two chambers. In this regard, a more specific aspect of the 
present invention generally relates to a shut-off valve module for this 
fluid connection. The shut-off valve device has at least one shut-off 
valve which separates a high-pressure section and a low-pressure section 
of the fluid connection. By means of a magnet armature and a magnet coil, 
the shut-off valve can typically have a shutoff body which can be adjusted 
between a closed and an open position by an external control. The high 
pressure section of the fluid connection can empty into a central channel, 
and a first side of the shut-off valve body, which first side can be 
pressurized by the high pressure section, can be elastically pressed 
against a shut-off valve seat by means of a compression spring. In 
addition, the first side of the shut-off valve body can be connected by 
means of an after-throttle to a second side of the shut-of valve body. 
2. Background Information 
One such shut-off valve module of the type described above is disclosed, 
for example, in German Patent No. 41 14 305. In general, for the 
development of an adjustable vibration damper with a shut-off valve 
module, the characteristics to be achieved by the vibration damper are 
specified by the vehicle manufacturer. The components of the conventional 
portion of the vibration damper, and also of the shut-off valve module, 
are then designed on the basis of these characteristics. It has been found 
however, that the vibration damper may generate unacceptable hissing 
noises. 
Even an experienced vibration damper designer can typically be unable to 
determine in advance whether the hissing noises will occur in the finished 
vibration damper. Basic tests have shown that the hissing noises are: 
essentially a function of the flow velocity of the damping medium, but no 
reproducible relationships have been found between the hissing noises and 
the individual components of the vibration damper. In constructing a 
vibration damper, the characteristics of the vibration damper must 
correspond to the needs of the particular vehicle. For this purpose, the 
sizes of the individual components can essentially be determined, but 
there are essentially no available measures for preventing hissing noises. 
OBJECT OF THE INVENTION 
The-object of the present invention is to use the simplest possible means 
to eliminate hissing noises in vibration dampers. 
SUMMARY OF THE INVENTION 
The invention teaches that this object can be achieved if, inside the fluid 
connection, there is a section which provides a pressure reduction by 
means of at least one throttle point in combination with a baffle device 
connected to the throttle point. During the pressure increase, a precise 
path is specified for the damping medium, which path leaves no free space 
for any spraying or foaming that might result in the generation of noise. 
In one particularly advantageous embodiment, the section for providing the 
pressure reduction can be formed by a thimble-like insert that fits into 
the fluid connection. In essence, this thimble-like insert can preferably 
be designed to be retro-fitted into a valve unit. As such, no 
reconstruction measures would typically be required on the finished 
vibration damper. The baffles and throttles can be formed by the 
thimble-like insert, and the thimble-like insert can be provided with at 
least one radial opening, the outlet of which opening can preferably be 
oriented radially toward the wall of the central channel. 
If the pressure decrease within the section for providing pressure 
reduction is insufficient, the present invention teaches that there can be 
at least one additional throttle point connected to the thimble-like 
insert, which throttle point has an offset with respect to the 
after-throttle. The additional throttle point can thereby form an 
additional smoothing or damping chamber, in conjunction with the 
thimble-like insert. 
In an alternative variant, the section for providing the reduction in 
pressure can preferably have a series arrangement of separate throttle 
cross sections, whereby the throttle cross sections can each be offset in 
relation to one another, and at least one throttle cross section can be 
realized inside a throttle plate. A throttle plate can also be inserted 
subsequently, or retro-fitted, as can the thimble-like insert, into an 
already assembled valve unit. It has thereby been determined to be 
particularly advantageous if the series arrangement is located in the 
central channel. 
In accordance with at least one embodiment of the present invention, valve 
units can thereby be pre-assembled, or produced in large quantities, 
without the above-discussed thimble-like insert, or throttle plate 
included therewith. Then, for individual vibration dampers of various 
kinds, tests could preferably be conducted to determine whether each of 
the various vibration dampers would hiss under various operating 
conditions and loads with the valve unit. If a hissing is determined to 
occur for one particular vibration damper under a particular set of 
operating conditions, all of the valve units which will be assembled to 
vibration dampers of that particular model can then be retro-fitted with 
the necessary pressure reducing elements. On the other hand, for vibration 
dampers which are found not make a hissing noise using that particular 
valve unit, no further valve assembly would then be necessary, and the 
pre-assembled valve units could be installed as is. 
The embodiments of the present invention as set forth above, will be 
discussed in more detail herebelow with reference to the accompanying 
drawings. It should be understood that when the word "invention" is used 
in this application, the word "invention" includes "inventions", that is, 
the plural of "invention". By stating "invention", Applicants do not in 
any way admit that the present application does not include more than one 
patentably and non-obviously distinct invention, and maintains the 
possibility that this application may include more than one patentably and 
non-obviously distinct invention. The Applicants hereby assert that the 
disclosure of this application may include more than one invention, and, 
in the event that there is more than one invention, that these inventions 
may be patentable and non-obvious, one with respect to the other. 
One aspect of the invention resides broadly in a vibration damper for a 
suspension of a motor vehicle for damping vibrations between a wheel and a 
frame of a motor vehicle, the vibration damper having an exterior, the 
exterior defining a side of the vibration damper, and the vibration damper 
comprising: a cylinder; the cylinder defining a chamber therewithin; the 
cylinder having a first end and a second end, and the cylinder defining a 
longitudinal dimension between the first end and the second end; apparatus 
for connecting the cylinder to one of: a wheel and a frame of a motor 
vehicle; a piston rod; the piston rod extending along the longitudinal 
dimension and extending through the first end of the cylinder; the piston 
rod having a first end within the cylinder and a second end outside of the 
cylinder; apparatus for connecting the piston rod to the other of: a wheel 
and a frame of a motor vehicle; a piston disposed at the first end of the 
piston rod; the piston dividing the chamber into a first chamber portion 
and a second chamber portion; damping fluid disposed within the first 
chamber portion and the second chamber portion; fluid passage apparatus 
connecting the first chamber portion and the second chamber portion for 
bypassing fluid around the piston; valve apparatus for regulating flow of 
damping fluid through the fluid passage apparatus; and an electromagnet 
for controlling operation of the valve apparatus; the valve apparatus 
being attached to the side of the vibration damper, and the valve 
apparatus comprising: a valve seat; a valve closure member disposed 
adjacent the valve seat for closing against the valve seat; apparatus for 
closing the valve closure member with respect Go the valve seat to 
substantially close the fluid passage apparatus; apparatus for permitting 
opening of the valve closure member with respect to the valve seat to open 
the fluid passage apparatus; the electromagnet comprising apparatus for 
operating at least one of: the apparatus for permitting opening and the 
apparatus for closing; at least one fluid passage portion disposed 
adjacent the valve seat, the at least one fluid passage portion defining a 
longitudinal direction extending away from the valve seat; and apparatus 
disposed in the at least one fluid passage portion for diverting fluid 
flow within the at least one fluid passage portion through at least one 
substantial angle with respect to the longitudinal direction. 
Another aspect of the invention resides broadly in a vibration damper for a 
motor vehicle for damping vibrations between first and second components 
of the motor vehicle, the vibration damper comprising: a cylinder; the 
cylinder defining a chamber therewithin; the cylinder having a first end 
and a second end, and the cylinder-defining a longitudinal dimension 
between the first and second ends thereof; apparatus for connecting the 
cylinder to one of the first and second components of a motor vehicle; a 
piston rod; the piston rod extending along the longitudinal dimension and 
extending through the first end of the cylinder; the piston rod having a 
first end within the first cylinder and a second end outside of the 
cylinder; apparatus for connecting the piston rod to the other of the 
first and second components of a motor vehicle; a piston disposed at the 
first end of the piston rod; the piston dividing the chamber into a first 
chamber portion between the piston and the first end of the cylinder, and 
a second chamber portion between the piston and the second end of the 
cylinder; damping fluid disposed within the first chamber portion and the 
second chamber portion; fluid passage apparatus connecting the first 
chamber portion and the second chamber portion for bypassing damping fluid 
around the piston; and valve apparatus for regulating flow of damping 
fluid through the fluid passage apparatus, the valve apparatus comprising: 
a valve seat; a valve closure member disposed adjacent the valve seat for 
closing against the valve seat; apparatus for permitting movement of the 
valve closure member with respect to the valve seat to substantially close 
the fluid passage apparatus; apparatus for permitting movement of the 
valve closure member with respect to the valve seat to open the fluid 
passage apparatus; at least one fluid passage portion disposed adjacent 
the valve seat, the at least one fluid passage portion defining a 
longitudinal direction extending away from the valve seat; at least a 
substantial portion of the at least one fluid passage portion having a 
cross-sectional dimension substantially transverse to the longitudinal 
direction; at least one throttle apparatus disposed in the at least one 
fluid passage portion for reducing a pressure of damping fluid flowing 
throw the at least one fluid passage portion; and the at least one 
throttle apparatus having an opening therethrough, the opening having a 
cross-sectional dimension, and the cross-sectional dimension of the 
opening being substantially less than the cross-sectional dimension of the 
at least a substantial portion of the at least one fluid passage portion. 
A still further aspect of the invention resides broadly in a kit for 
reducing noise produced by damping fluid moving within a damping valve of 
a vibration damper, the vibration damper comprising: a cylinder; the 
cylinder defining a chamber therewithin; the cylinder having a first end 
and a second end, and the cylinder defining a longitudinal dimension 
between the first and second ends; a piston rod; the piston rod extending 
along the longitudinal dimension and extending through the first end of 
the first cylinder; the piston rod having a first end within the first 
cylinder and a second end outside of the first cylinder; a piston disposed 
at the first end of the piston rod; the piston dividing the chamber into a 
first chamber portion and a second chamber portion; dumping fluid disposed 
within the first chamber portion and the second chamber portion; fluid 
passage apparatus connecting the first chamber portion and second chamber 
portion for bypassing damping fluid around the piston; and the damping 
valve, the damping valve comprising valve apparatus for regulating flow of 
damping fluid through the fluid passage apparatus, the valve apparatus 
comprising: a valve seat; a valve closure member disposed adjacent the 
valve seat for closing against the valve seat; apparatus for permitting 
movement of the valve closure member with respect to the valve seat to 
substantially close the fluid passage apparatus; apparatus for permitting 
movement of the valve closure member with respect to the valve seat to 
open the fluid passage apparatus; at least one fluid passage portion 
disposed adjacent the valve seat, the at least one fluid passage portion 
defining a longitudinal direction extending away from the valve seat, at 
least a substantial portion of the at least one fluid passage portion 
having a cross-sectional dimension substantially transverse to the 
longitudinal direction; and the kit comprising: a member for being 
inserted into the at least one fluid passage portion, the member 
comprising: apparatus for substantially reducing the cross-sectional 
dimension of an additional portion of the at least one fluid passage 
portion.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In FIG. 1, the cylinder of a vibration damper is designated 1, and the 
piston rod is designated 3. The cylinder 1 can typically be closed on one 
end, generally the bottom, by a base 5. The base 5 can generally be 
provided with a connection device 4 for connecting the bottom end of the 
cylinder 1 to, for example, the wheel suspension of a motor vehicle. A 
general depiction of a motor vehicle 100 and vibration damper unit 104 is 
shown in FIG. 4. In FIG. 4, the wheels of the motor vehicle are designated 
as 103, a frame portion as 101, and a suspension system (shown only 
schematically) as 102. 
As shown in FIG. 1, the piston rod 3 typically extends out of the cylinder 
1 through an end of the cylinder 1 opposite to the base 5, i.e. an upper 
end in this depiction. The piston rod 3 can extend through a guide and 
seal unit 7 to thereby provide a seal about the piston rod 3 and seal the 
interior of the vibration damper from the exterior. At the protruding end 
2 of the piston rod 3, there can preferably be a second connection device 
6 for connecting the piston rod 3 to the frame of the motor vehicle, or 
alternatively to another component of the suspension system. 
Inside the cylinder 1, a piston, or piston unit 9 can be fastened to the 
piston rod 3. The piston unit 9 can preferably be provided with a piston 
valve system 11. The lower end of the cylinder 1 can be closed by a base 
plate 13, which base plate 13 can be provided with a base valve system 15. 
The cylinder 1 can be enclosed by a container tube 17. Between the 
container tube 17 and the cylinder 1, an annular space 19 can preferably 
be formed. This annular space 19 essentially provides an equalization 
chamber for the space within the cylinder 1. 
The space inside the cylinder 1 can be divided by the piston unit 9 into a 
first, or lower, work chamber 21a and a second, or upper, work chamber 
21b. The work chambers 21a and 21b can be essentially completely filled 
with hydraulic fluid. The equalization chamber, or annular space 19 can be 
filled up to the level 19a with fluid and above that with gas. The 
expandability of the gas essentially provides volume compensation within 
the cylinders 1 and 17 to compensate for the volume of the piston rod 3 as 
the piston rod 3 is moved into and out of the cylinder 1. 
Inside the equalization chamber 19, an additional cylinder 10 can be 
provided about the cylinder 1 to form a fluid bypass 12 between cylinders 
1 and 10 for bypassing fluid around the piston unit 9 between the work 
chambers 21a and 21b. The fluid bypass 12 can have a first segment, namely 
a high-pressure segment 23, which high-pressure segment 23 can be 
connected by means of a hole 25 of the cylinder 1 with the second work 
chamber 21b. Connected to this high-pressure segment 23 there can 
preferably be a shut-off valve device 27. Further details regarding the 
shut-off valve device 27 are provided herebelow. In the depicted 
embodiment of FIG. 1, the shut-off valve device 27 is shown attached 
laterally to the container tube 17. From this shut-off valve device 27, a 
second segment (not shown here but described later with reference to FIGS. 
2 and 3), namely a low-pressure segment, can extend to the equalization 
chamber 19. 
When the piston rod 3 is moved out of the cylinder 1, in an upward 
direction in FIG. 1, the upper work chamber 21b would be reduced in size. 
An overpressure can thereby form in the upper work chamber 21b. The 
overpressure can be at least partially reduced by the piston valve system 
11, whereby the piston valve system 11 can permit fluid flow therethrough 
and into the lower work chamber 21a. As long as the shut-off valve device 
27 is closed, the valve system 11 provides essentially the sole system for 
permitting fluid flow between chambers 21a and 21b. When the shut-off 
valve device 27 is opened, fluid can then flow from the upper work chamber 
21b, simultaneously through both the valve system 11 into chamber 21a, and 
also through the high pressure segment 23, the shut-off valve device 27, 
the equalization chamber 19 and into lower chamber 21a. The damping 
characteristic of the vibration damper during the movement of the piston 
rod 3 out of the cylinder 1 can therefore essentially be a function of 
whether the shut-off valve device 27 is open or closed. 
When the piston rod 3 moves into the cylinder 1, an overpressure can be 
formed in the lower work chamber 21a. Fluid can then travel from the lower 
work chamber 21a through the piston valve system 11 upward into the upper 
work chamber 21b. The fluid displaced by the increasing piston rod volume 
inside the cylinder 1 can be expelled through the base valve system 15 
into the equalization chamber 19. Since the flow resistance of the piston 
valve system 11 can typically be less than the flow resistance of the base 
valve system 15, an increasing pressure can again occur in the upper work 
chamber 21b. When the shut-off valve device 27 is open, this increasing 
pressure can flow through the high pressure segment 23 into the 
equalization chamber 19. That means that when the shut-off valve device 27 
is open, the vibration damper can also have a softer characteristic when 
the rod 3 is moving into the cylinder, and a harder characteristic when 
the shut-off valve device 27 is closed, i.e. when the piston rod 3 is 
moving out of the cylinder. Because of the flow resistance as discussed 
above, the flow direction through the high-pressure segment 23 of the 
bypass 12 can generally always be the same, regardless of whether the 
piston rod 3 is moving into or out of the cylinder 1. 
An additional component of a vibration damper, as shown in FIG. 1, can 
include an outer cylindrical sleeve 14 attached to the end 2 of the piston 
rod 3. This sleeve 14 can preferably protect the piston rod 3 when the 
piston rod 3 is pulled out of the cylinder 1. 
FIG. 2 shows a cross section of cylinder 1, with the high-pressure segment 
23 of the bypass 12 and the equalization chamber 19. Connected to the 
high-pressure segment 23 there can be a central channel 29, which central 
channel 29 corresponds to the shut-off valve device 27. In the upper end 
of the central channel 29, there can be a shut-off valve seat 31. A 
shut-off valve body, preferably in the form of a rigid shut-off valve 
plate 33, can be in contact with the shut-off valve seat 31. In FIG. 2, 
the shut-off valve plate 33 is shown in its shut-off position, whereby the 
connection between the central channel 29 and the equalization chamber 19 
by means of holes 35 would then essentially be closed. The shut-off valve 
plate 33 can be biased, by means of a coil compression spring 37, toward 
the shut-off valve seat 31. The spring 37 can be supported on a 
separation, or partition plate 39. The plate 33 can preferably move under 
a sufficient pressure acting on surface 33a thereof a distance (a) to abut 
against a blocking member 59a. 
Located in the shut-off valve device 27, concentric to the central channel 
29, there can be a magnet armature 41. This magnet armature 41 can be 
biased downwardly, by a magnet armature prestress spring 43, toward the 
shut-off valve plate 33, and can be pulled upward by a magnet winding 44 
when a current is sent through this magnet winding 44. 
Between the magnet armature 41 and the shut-off valve plate 33, there can 
preferably be an intermediate body module 45, 47. The intermediate body 
module 45, 47 can comprises a control chamber discharge valve body 45 and 
a supplementary discharge valve body 47. 
A passage 41a in the magnet armature 41 connects a spring chamber 41b, 
which spring chamber 41b houses the magnet armature prestress spring 43, 
with a space 49 located between the supplementary discharge valve body 47 
and the shut-off valve plate 33. A passage 47a can be provided in the 
supplementary discharge valve body 47, and a passage 45a can be provided 
by the control chamber discharge valve body 45. Together, the passage 47a 
in the supplementary discharge valve body 47, and the passage 45a of the 
control chamber discharge valve body 45, passage 41a of the magnet 
armature 41, spring chamber 41b and a space 41c located above the magnet 
armature, can form a control chamber 50. 
The underside of the shut-off valve plate 33 is designated 33a, and the 
upper side is designated 33b. The shut-off valve plate 33 is exposed from 
below to the pressure (P) in the central channel 29, i.e. the pressure in 
the upper work chamber 21b, illustrated in FIG. 1, and in the high 
pressure segment 23. 
The shut-off valve plate 33 is located in a basin-shaped insert 51. The 
basin-shaped insert 51 has the hole 35 and has a tube socket 51a, directed 
downwardly in FIG. 2. This tube socket 51a forms the central channel 29 
and is preferably tightly connected, by means of a seal 53, to the first 
segment 23 of the bypass. The basin-shaped insert 51 can be inserted in a 
tube socket 55, which tube socket 55 can be welded to the container 17. 
The space between the basin-shaped insert 51 and the tube socket 55 forms 
a low-pressure segment 23a of the bypass 12. Together, the high-pressure 
segment 23 and the low-pressure segment 23a form the bypass 12. Placed on 
the basin 51 is the separation plate 39, which separation plate 39 can 
form a module together with the iron parts corresponding to the magnet 
winding 44 and the housing parts. 
When the magnet windings 44 are not carrying a current, the control chamber 
discharge valve body 45 can be in the shut-off position, illustrated in 
FIG. 2, wherein a cone 45b of the control chamber valve body 45 rests on a 
ring zone 47b of the supplementary discharge valve body 47, which ring 
zone 47b forms the control chamber discharge valve seat. A coil 
compression spring 57 prestresses, or biases the control chamber discharge 
valve body 45 away from the control chamber discharge seat 47b. The 
control chamber discharge valve body 45 can be guided in a sealed manner 
in a tubular extension 41d of the magnet armature 41. As a result of the 
supplementary closing force generated by the magnet armature bias spring 
43, in the illustrated shut-off position of the control chamber discharge 
valve 45, 47b, the magnet armature 41 can lie on the control chamber 
discharge valve body 45 and hold the valve body in its shut-off position 
against the force of the spring 57. 
The pressure prevailing in the control chamber 50 is essentially 
transmitted to the entire reverse side 45c of the control chamber 
discharge valve body 45 by means of channels 41e formed in the magnet 
armature 41. Since the control chamber discharge valve body 45 presents a 
larger pressurization surface 45c to the pressure (P) in the control 
chamber 50 than does the supplementary discharge valve body 47 in the 
vicinity of the space, or chamber 49, the pressure (P) in the control 
chamber 50 can essentially exert a hydraulic closing force directed 
downward on the intermediate body module 45, 47. In this position, the 
maximum stroke travel (h.sub.s) can essentially be available for the 
magnet armature 41. 
When the magnet winding 44 is energized in response to an opening command 
from the external signal source, the magnet armature 41 can consequently 
be raised from the control chamber discharge valve body 45 so that the 
magnet armature 41 can travel the entire stroke distance (h.sub.s). Then, 
the control chamber discharge valve body 45 can remain in its shut-off 
position when the pressure (P) in the control chamber 50 is greater than a 
predetermined limit value (P.sub.G) of the pressure, since the hydraulic 
closing force exerted by the pressure (P) on the reverse side 45c of the 
control chamber discharge valve body 45 can be greater than the opening 
force exerted by the spring 57 on the control chamber discharge valve body 
45. 
If the pressure (P) in the control chamber 50 is less than the limit value 
(P.sub.G), as a result of the reduction of the pressure in the central 
channel 29, then the control chamber discharge valve body 45, on account 
of the now dominant spring force of the spring 57, can be raised from the 
control chamber discharge valve seat 47b. Damping fluid can then flow 
between the control chamber discharge valve body 45 and the control 
chamber discharge valve seat 47b, through to the equalization chamber 19. 
As a result, the pressure (P) acting on the reverse side 45c can be 
reduced to the extent that the control chamber discharge valve body 45, as 
a result of the force of the spring 57, can be raised completely from the 
control chamber discharge valve seat 47 and the passage 45a can be 
completely opened. At high flow rates, as a result of the pressure 
decrease which can occur at the passage 45a, a force directed toward the 
opening of a supplementary discharge valve (formed by the valve body 47 
and a seat 63) can be exerted on the supplementary discharge valve body 
47, and the supplementary discharge valve 47, 63 opens. The shut-off valve 
33, 31 can then act together with the spring 37 as a standard 
spring-loaded damping valve. 
To eliminate noises caused by fluid flow through the bypass 12, the central 
channel 29 can preferably be provided with a thimble-like insert 65. This 
insert 65, can be fastened by partial deformations 67 of the tube socket 
51. In the insert 65 there can be radial openings 69, and the outlet of 
the openings 69 can be directed toward the wall of the central channel 29. 
Adjacent to the thimble-like insert 65 there can be an additional throttle 
point 71. The throttle point 71 can preferably be configured with an 
extension 71a, in this embodiment a radial extension. The extension 71a 
essentially is provided to prevent the flow, which bypasses, or flows past 
a baffle, from striking the shut-off valve plate 33 directly. 
With the thimble like insert 65 in place, any damping medium flowing under 
high pressure into the central channel 29 would strike an end surface 73 
of the thimble-like insert 65, and would be deflected by the insert 65 
into the radial openings 69. The wall of the central channel 29, together 
with the outer surface of the thimble-like insert 65, forms a smoothing 
chamber 75 which effectively prevents a foaming of the damping medium as 
the damping medium exits from the radial openings 69. 
From the smoothing chamber 75, the damping medium flows via the additional 
throttle point 71 toward the underside 33a of the shut-off valve plate 33. 
A second smoothing chamber 77 can be formed by the additional throttle 
point 71 in connection with the under side 33a of valve plate 33. 
The series connection of the throttle points in connection with the 
smoothing chambers 75, 77 essentially provides a controlled pressure 
decrease, to decrease the pressure to a pressure level which is necessary 
for the desired characteristics. As a result of the smoothing chambers, 
there is a controlled baffling, or deflection of the damping fluid to 
thereby prevent noise. 
The thimble-like insert 65 can also be retro-fitted into a series of 
already assembled vibration dampers, if noises are generated by the 
vibration dampers. For retro-fitting, the valve devices 27 would 
essentially need to be disassembled from the container tube 17, at which 
juncture a thimble-like insert 65 could simply be inserted into the 
central channel 29, and the valve device 27 could be re-attached to the 
container tube 17. 
In one alternative embodiment, as illustrated in FIG. 3, instead of the 
thimble-like insert 65, there can be a throttle plate 79 inserted in the 
central channel 29. The throttle plate 79 can have a throttle opening 81. 
Here again, the throttle openings 71, 81 have a radial or circumferential 
offset for a deflection of the flow path. The distance of the throttle 
plate 79 from the additional throttle point 71 in the tube socket 51, 
together with the wall of the central channel 29, forms the smoothing 
chamber 75. It can then be seen that several smoothing chambers 75 could 
be realized by means of a series arrangement of throttle plates 79. The 
desired damping force characteristics of the vibration damper essentially 
dictate the size of the opening cross sections of the throttles 71, 79, as 
well as the distances between the throttle plates 79 and the distance 
between the outlet of the radial openings 69 of the thimble-like insert 65 
and the wall, as illustrated in FIG. 2. 
In general, the thimble-like insert 65 and throttle plate 79 provide a 
simple device which can be inserted into pre-existing openings of a 
central channel 29 of a valve device 27, to essentially divert the flow of 
damping medium from a substantially straight line. In other words, 
substantially linear flow of damping fluid into contact with the valve 
plate 33 is essentially prevented. 
In the embodiment of FIG. 2, the fluid flow can be diverted through a 
plurality of substantial angles in flowing from the high pressure segment 
23 to the annular space 19. As can be seen, after entering the 
thimble-like insert 65, in a direction towards the plate 33, the fluid 
would be first diverted about 90.degree. and radially outwardly. From this 
flow direction, the fluid would then be diverted about 180.degree. and 
radially inwardly, and then a final diversion of about 90.degree. would 
put the fluid back into its original direction of movement toward the 
plate 33. 
Similarly, in the embodiment of FIG. 3, the fluid would essentially be 
diverted through two maximum angles of about 90.degree. each, and where it 
could be seen that minimum angles of diversion could possibly be two 
angles of about 45.degree. each. 
Each of the two above-discussed embodiments also generally have, in 
addition to changes in flow direction, changes in flow cross-section as a 
result of the various passage portions of different cross section. In FIG. 
3, there are at least the two openings 71 and 81 which have significantly 
smaller cross-sections than the central passage 29 and chamber 75. In this 
respect, the diameter ratios of the opening 71 and 81 with respect to the 
central passage 29 can preferably be about 1:3 and about 4:9, 
respectively, and could also encompass a range of ratios between these two 
values. Similar ratios are also present in FIG. 2, wherein, instead of a 
single opening 81 as in FIG. 3, the embodiment of FIG. 2 has two openings 
69, of a smaller diameter than the opening 81 of FIG. 3. Fluid flowing 
through these restricted openings is therefore going to undergo several 
changes in flow rate and pressure, which when going from a higher pressure 
in a restricted passage to a lower pressure in a wider passage creates a 
smoothing effect in the fluid flow. 
One feature of the invention resides broadly in the shut-off valve device 
between two portions of a fluid connection which connects two fluid 
chambers of a vibration damper to one another, whereby the shut-off valve 
device has at least one shut-off valve which separates a high-pressure 
section and a low-pressure section, and the latter shut-off valve has a 
shutoff body which can be adjusted by an external control by means of a 
magnet armature and a magnet coil between a closed and an open position, 
whereby the high pressure section empties into a central channel, and a 
first side of the shut-off valve body which is pressurized by the high 
pressure section can be elastically pressed against a shut-off valve seat 
by means of a compression spring, whereby the first side of the shut-off 
valve body is connected by means of an after-throttle to a second side of 
the shut-off valve body, characterized by the fact that in the fluid 
connection 23, there is a line segment which has a pressure reduction by 
means of at least one throttle point 67, 71, 81 in combination with a 
baffle device 65, 75, 77, 79 which is connected to the throttle point. 
Another feature of the invention resides broadly in the shut-off valve 
device characterized by the fact that the line segment is formed by a 
thimble-like insert 65. 
Yet another feature of the invention resides broadly in the shut-off valve 
module characterized by the fact that the thimble-like insert 65 has at 
least one radial opening 69, the outlet of which is oriented toward the 
wall of the central channel 29. 
Still another feature of the invention resides broadly in the shut-off 
valve module characterized by the fact that connected to the thimble-like 
insert 65 is at least one additional throttle point 71, which has an 
offset with respect to the after-throttle 61. 
A further feature of the invention resides broadly in the shut-off valve 
module characterized by the fact that the line segment has a series of 
throttle cross sections 71, 81 at some distance from one another, whereby 
the throttle cross sections are each offset from one another, and at least 
one throttle cross section 81 is realized inside a throttle plate 79. 
Another feature of the invention resides broadly in the shut-off valve 
module characterized by the fact that the series is located inside the 
central channel 29. 
Some additional examples of vibration dampers, and the components thereof, 
which could possibly be used in conjunction with components as set forth 
above in the context of the present invention, might be, or are disclosed 
by the following U.S. Pat. No. 5,353,897 to Felix Wossner, entitled 
"Vibration Damper"; U.S. Pat. No. 5,353,898 to Handke et al., entitled 
"Vibration Damper Unit"; U.S. Pat. No. 5,363,945 to Lizell and Vanroye, 
entitled "Control Valve for Shock Absorbers"; U.S. Pat. No. 5,184,703 to 
Wilhelm Van Zeggeren, entitled "Shock Absorber with Piston Valve for 
Adjustable Damping"; U.S. Pat. No. 5,201,388 to Tommy Malm, entitled 
"Shock Absorber"; U.S. Pat. No. 5,248,014 to Masahiro Ashiba; U.S. Pat. 
No. 5,303,804 to Ewald Speiss, entitled "Shock Absorber for Damping 
Courses of Motion of A Vehicle"; U.S. Pat. No. 5,305,860 to Rotharmel 
etal., entitled. "Remote Controlled Vehicle Damper"; and U.S. Pat. No. 
5,332,069 to Murakami, entitled "Shock Absorber". 
The components disclosed in the various publications, disclosed or 
incorporated by reference herein, may be used in the embodiments of the 
present invention, as well as, equivalents thereof. 
All, or substantially all, of the components and methods of the various 
embodiments may be used with at least one embodiment or all of the 
embodiments, if more than one embodiment is described herein. 
The corresponding foreign patent publication applications, namely, Federal 
Republic of Germany Patent Application No. P 44 24 436.3, filed on Jul. 
12, 1994, having inventors Otto Samonil, and DE-OS P 44 24 436.3 and DE-PS 
P 44 24 436.3, any of the documents cited herein, are hereby incorporated 
by reference as if set forth in their entirety herein. 
The details in the patents, patent applications and publications may be 
considered to be incorporable, at applicant's option, into the claims 
during prosecution as further limitations in the claims to patentably 
distinguish any amended claims from any applied prior art. 
The invention as described hereinabove in the context of the preferred 
embodiments is not to be taken as limited to all of the provided details 
thereof, since modifications and variations thereof may be made without 
departing from the spirit and scope of the invention.