Hydrodynamic clutch device with a dividing wall between a hydrodynamic circuit and a residual circuit

A hydrodynamic clutch device is formed with a hydrodynamic circuit comprising at least an impeller and turbine wheel and with a residual circuit in which is provided at least a lockup clutch for fixing the turbine wheel relative to a drive. The residual circuit is supplied, via a hydraulic supply system, with switchable pressure medium lines for controlling the lockup clutch. The hydrodynamic circuit is at least substantially isolated from the residual circuit by a dividing wall and is at least partially filled with a medium whose density exceeds that of the medium used for supplying the residual circuit.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention is directed to a hydrodynamic clutch device with a 
hydrodynamic circuit including a turbine wheel and an impeller wheel and a 
residual circuit including a lockup clutch for selectively fixing the 
turbine wheel relative to a drive. 
2. Description of the Related Art 
A hydrodynamic clutch device in the form of a torque converter, whose 
hydrodynamic circuit comprises an impeller, turbine and stator, is known 
from German reference DE 41 21 586 Al, particularly from FIG. 1 and the 
associated part of the specification. Apart from this hydrodynamic 
circuit, the clutch housing further comprises a lockup clutch which is 
provided for fixing the turbine wheel relative to a drive, e.g., the 
crankshaft of an internal combustion engine, and which is supplied via a 
hydraulic supply system with switchable pressure medium lines for 
controlling the lockup clutch. A torsional vibration damper acting between 
the lockup clutch and the turbine wheel is also provided. 
In hydrodynamic clutch devices of this type, the hydrodynamic circuit is 
bridged increasingly earlier for reasons pertaining to wear and, as the 
case may be, is utilized purely as a starting element. Since many drives, 
particularly internal combustion engines, generate relatively large 
torsional vibrations at comparatively low speeds, the earlier bridging 
times require that these torsional vibrations at low speeds must be 
compensated in the torsional vibration damper, so that torsional vibration 
dampers of increasingly larger volume are used. In view of the fact that 
the lockup clutch offers only very little leeway in terms of design for 
gaining axial installation space, a large torsional vibration damper can 
be carried out only at the expense of the axial extension of the 
hydrodynamic circuit. This results in hydrodynamic circuits which are 
increasingly narrower in the axial direction which leads to a reduced 
through-flow cross section between the other and inner torus and to 
decreased throughput, thereby reducing the starting torque of the torque 
converter. One solution is to axially flatten the construction of the 
inner torus. However, in conjunction with the axially narrow construction 
of the outer torus, this would produce flow problems between the 
individual running wheels, such as partial reflux and dead zones for flow, 
reducing the efficiency of the hydrodynamic circuit. Therefore, this 
solution increases starting torque at the cost of reduced efficiency. 
In torque converters, the starting torque may also be influenced by the 
blade angle of the running wheels. However, an adjustment of the blade 
angles also affects the starting transmission ratio, which can have 
negative consequences depending on the intended use of the torque 
converter. 
A further solution for increasing the starting torque is to increase the 
diameter of the hydrodynamic circuit, so that, as a result of the 
dependence of the pump torque on the outer diameter of the hydrodynamic 
circuit as D.sup.5, the starting torque of the pump can be appreciably 
increased by only a slight increase in diameter. However, the increased 
inertia in the running wheels and the greater radial installation space 
requirement of even a slight increase in diameter are disadvantageously 
noticeable. 
Hydraulic clutches which have narrower axial dimensions owing to the 
absence of the stator wheel and which also usually have a hydrodynamic 
circuit with a comparatively small cross section may be used as an 
alternative to torque converters. Compared with a torque converter, 
hydraulic clutches of this type have the disadvantage that there is no 
starting gear multiplication due to the absence of the stator. Further, 
the starting torque in hydraulic clutches of the type mentioned above is 
small, especially when the hydrodynamic circuit has a small cross section 
because of the small diameter ratio between the outer and inner diameter 
of the impeller and turbine. 
SUMMARY OF THE INVENTION 
It is the object of the invention to provide a hydrodynamic clutch device 
in the most economical design possible such that a high starting torque is 
achieved without the problems of the prior art. 
The object is met according to an embodiment of the invention by a 
hydrodynamic clutch device connectable to a drive, comprising a 
hydrodynamic circuit comprising an impeller wheel connectable with the 
drive and rotatably mounted about an axis of rotation and a turbine wheel 
rotatably mounted about said axis of rotation, said hydrodynamic circuit 
being filled with a first medium having a first density, a residual 
circuit comprising a lockup clutch having a plurality of clutch components 
operatively connected for selectively fixing said turbine wheel to a 
component connected with said impeller wheel, a hydraulic supply system 
having switchable pressure medium lines operatively connected to said 
residual circuit for supplying a second medium to said residual circuit 
for controlling said lockup clutch, wherein a density of said first medium 
exceeds a density of said second medium, and a dividing wall arranged for 
substantially isolating said hydrodynamic circuit from said residual 
circuit. 
According to the invention, the starting torque of the hydrodynamic circuit 
and its clutch device may be increased by using a medium of higher 
density. However, suitable media for this purpose are either expensive, 
result in increased wear with respect to the lockup clutch such, for 
example, as when the elevated density is achieved through the addition of 
solid particles of very high density to a carrier fluid, or may cause 
undesirable behaviour of the clutch device with respect to coefficient of 
friction, cooling and lubrication. Accordingly, the clutch device using 
the medium of higher density must be constructed to ensure that the 
higher-density medium is used only at the location in the clutch device 
where it achieves a beneficial effect, i.e., only in the area of the 
hydrodynamic circuit, while a suitable inexpensive medium flows through 
the residual circuit of the clutch device having the lockup clutch and, 
where appropriate, a torsional vibration damper. Accordingly, the clutch 
device of the present invention is divided into two circuits by a dividing 
wall which is fastened to a structural component part of the clutch such, 
for example, as the clutch housing and which contacts, via a seal, a 
second structural component part of the clutch such, for example, as a 
structural component part of the turbine wheel which is movable relative 
to the first structural component part of the clutch. This arrangement has 
the following results: 
A space is formed in the clutch device which houses the hydrodynamic 
circuit and is filled with a medium of higher density. Both the dividing 
wall and the seal are constructed such that the medium cannot exit the 
space under any circumstances. In this manner, a relatively small quantity 
of higher-density medium is sufficient for increasing the starting torque 
of the clutch device, so that costs for this medium are kept low. 
Since the higher-density medium is not exchanged, but always remains inside 
the space receiving the hydrodynamic circuit, this medium may be easily be 
formed by introducing solid particles of high density into an optional 
carrier fluid. Graphite powder is particularly suitable as solid particles 
because it has a lubricating effect in addition to a density-elevating 
effect. 
During the operation of the hydrodynamic circuit, the higher-density medium 
may become heated as a result of slippage. However, this heating is not 
critical because a conventional medium, e.g., mineral oil, flows through 
the residual circuit in a manner typical of hydrodynamic clutch devices. 
This medium flows from a hydraulic supply system and is returned to this 
supply system after flowing through the residual circuit. When flowing 
through the residual circuit, this medium is also guided along the side of 
the dividing wall remote of the hydrodynamic circuit and therefore 
conducts heat that has been transferred from the higher-density medium to 
the dividing wall out of the clutch device. This arrangement effectively 
prevents an overheating of the hydrodynamic circuit. A constant feed of 
fresh medium in the residual circuit is always ensured because, for 
example, the adjustment of the lockup clutch in a determined position is 
carried out depending on the pressure ratios within the residual circuit. 
Because the hydrodynamic circuit is sealed, a slight heating of the 
higher-density medium in the hydrodynamic circuit results in a pressure 
increase in the corresponding space. To compensate for this pressure 
increase, the dividing wall may be constructed as a diaphragm-like 
element, so that the dividing wall counters a rise in pressure through 
natural deformation. Alternatively, when a more rigid dividing wall is 
used the seal is constructed in such a way that it substantially prevents 
a rise in pressure in the hydrodynamic circuit. For this purpose, for 
example, sealing elements of the seal may be arranged so as to be movable. 
The movement of the sealing elements provides for a change in volume of 
the space receiving the hydrodynamic circuit through their movement 
relative to the dividing wall. Another possible seal enables a deliberate 
leakage flow of viscous medium between the two circuits. Since the 
hydrodynamic circuit has a comparatively small volume, even a small 
leakage flow is sufficient for a pressure compensation. Such pressure 
compensation is useful because, for example, during operation of the 
hydrodynamic circuit the medium located therein is thrown radially outward 
due to centrifugal force, so that a vacuum can develop in the radial inner 
area, which solves the problem of cavitation. Therefore, an excessive 
pressure drop in the radial inner area of the hydrodynamic circuit must be 
avoided under all circumstances. 
Returning to the subject of the permeability of the seal for a small 
leakage flow of viscous medium, it is noted that the medium of higher 
density must on no account exit from the hydrodynamic circuit. Therefore, 
the seal is constructed in such a way that when the clutch device is at a 
standstill the force of gravity acting on the medium present in the 
hydrodynamic circuit is not sufficient to push the higher-density medium 
past the seal into the residual circuit. The seal should permit a leakage 
flow only when there is a determined pressure difference between the two 
circuits, wherein an overpressure is built up in the residual circuit due 
to the constant feed of hydraulic fluid. A vacuum in the radial inner area 
of the hydrodynamic circuit coincides with the overpressure in the 
residual circuit because, as was already explained, the higher-density 
medium in the hydrodynamic circuit is thrown radially outward as a result 
of centrifugal force during operation of the clutch device. Due to the 
resulting pressure difference on either side of the seal, medium is sucked 
out of the residual circuit into the hydrodynamic circuit via the seal. 
This medium remains on the radial inner side because of its lower density 
in comparison with the medium already located in the hydrodynamic circuit 
and accordingly serves as buffer fluid. Conversely, a thermally induced 
overpressure in the hydrodynamic circuit results in that the 
above-mentioned buffer fluid, that is, the lower-density medium, is pushed 
back into the residual circuit via the seal. Accordingly, exclusively 
lower-density medium flows through the seal as residual leakage. 
Suitable seals for operation of the type described above may, for example, 
comprise easily deformable elastomer seals or seals with at least one 
spring-loaded sealing means, i.e., sliding ring seals. Since the seal may 
assume the function of pressure compensation in the hydrodynamic circuit, 
the seal may reasonably act as a valve element. Of course, an additional 
valve element may also be used as an alternative to a dividing wall acting 
as a diaphragm-like element or a pressure-compensating seal. 
The medium of higher density used in the hydrodynamic circuit may be formed 
not only by the addition of solid particles of high density to a carrier 
fluid, but also by special fluids such as high-density oils such, for 
example, as polyglycol and silicone oil. 
It is noted by way of addition that the solution according to the 
invention, namely, filling a sealed hydrodynamic circuit with a medium of 
higher density, can be applied in a torque converter whose hydrodynamic 
circuit has a stator as well as in a hydraulic clutch with a hydrodynamic 
circuit not having a stator. 
The various features of novelty which characterize the invention are 
pointed out with particularity in the claims annexed to an forming a part 
of the disclosure. For a better understanding of the invention, its 
operating advantages, and specific objects attained by its use, reference 
should be had to the drawing and descriptive matter in which there are 
illustrated and described preferred embodiments of the invention.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
A hydrodynamic clutch element shown in FIG. 1 is a torque converter 200 
with a clutch housing 1 which has a radial flange 3 on a side of the 
hydrodynamic clutch element facing a drive 7, e.g., the crankshaft 9 of an 
internal combustion engine. The radial flange 3 has a bearing journal 5 in 
the area of a center axis 4 which is insertable in a corresponding recess 
of the crankshaft 9. The radial flange 3 is fixedly connected with an 
impeller shell 11 which includes an impeller hub 13 connected on a 
radially inner end of the impeller shell and extending in the direction of 
the power output connection, e.g., a transmission. The impeller shell 11 
is constructed with a vane arrangement 15 to form an impeller wheel 17. 
This impeller wheel 17 cooperates with a turbine wheel 23 having a turbine 
shell 19 and a vane arrangement 21 fastened thereto. A radially inner end 
of the turbine shell 19 forms a turbine base 24 which is in an operative 
connection via a toothing 27 with a turbine hub 25. A driven shaft 62 
which is typically a transmission input shaft is operatively connected to 
the turbine base 24 via the turbine hub 25. 
A stator wheel 31 is arranged axially between the impeller wheel 17 and 
turbine wheel 23 and, together with the two above-mentioned wheels 17 and 
23, forms a hydrodynamic circuit 32. The stator wheel 31 has a stator 
wheel hub 29 which receives a vane arrangement 33 and has a guide 39 for 
each spring-loaded sealing means 37 in axial recesses. The spring loaded 
sealing means 37 is part of a seal 34 formed as a sliding ring seal 35. 
One of the spring-loaded sealing means 37 axially contacts the impeller 
shell 11 and the other axially contacts the turbine base 24 of the turbine 
shell 19, thereby scaling the hydrodynamic circuit 32 on the radial inner 
side. 
The stator wheel hub 29 of the stator wheel 31 is arranged on a freewheel 
41 which is axially fixed between the impeller shell 11 and the turbine 
shell 19 via axial bearings 43 and is supported via a toothing at a 
freewheel support 60 which extends radially inside of the impeller hub 13. 
The freewheel support 60 and the impeller hub 13 enclose an annular 
channel 66. The freewheel support 60 in turn encloses the driven shaft 62 
while forming an annular channel 68 therebetween. The two annular channels 
66 and 68 act as a pressure medium line 69. The driven shaft 62 has a 
center bore 64 which acts as a pressure medium line 65. These two pressure 
medium lines 65 and 69 are connected, via a switching valve 70, with a 
supply reservoir 72 for viscous medium. A pump 74 is associated with this 
supply reservoir 72 for delivery of the viscous medium to one of the 
pressure lines 65 and 69, depending on the position of the switching valve 
70. The supply reservoir 72 is usually filled with a medium 106 of 
relatively low density such, for example, as mineral oil. 
Returning to the construction design of the torque converter 200, a side of 
the turbine hub 25 facing the radial flange 3 contacts the radial flange 3 
via an axial bearing 76 having radial grooves 78 on both sides. Further, 
the turbine hub 25 has a circumferential surface for receiving a piston 82 
of a lockup clutch 84. A radially outer area of the piston 82 carries a 
friction facing 86 which can be brought into contact with a friction 
surface 88 at the adjacent radial flange 3 of the clutch housing 1. A 
first chamber 80 remains axially between the piston 82 and the radial 
flange 3, while a second chamber 110 is provided on the side of the piston 
82 facing the hydrodynamic circuit 32. The piston 82 is axially 
displaceably arranged on the turbine hub 25. 
A torsional vibration damper 90 is provided at the side of the piston 82 
facing the hydrodynamic circuit 32. An input part 92 of the torsional 
vibration damper 90 includes two cover plates which are connected by 
riveting 95 with the piston 82. The input part 92 abuts one end of 
circumferential springs 97 which are supported at the other end at a hub 
disk 99. A radially inner area of the hub disk 99 is connected with a yoke 
102 via a tooth engagement 100 and cooperates with this yoke 102 as an 
output part 103 of the torsional vibration damper 90. The yoke 102 is 
fastened to a radial projection 105 of the turbine hub 25 and, via the 
rest of the torsional vibration damper 90, provides for a rotational 
connection of the piston 82 with the turbine hub 23, which rotational 
connection is elastic in the circumferential direction. 
A dividing wall 53 is fastened axially between the torsional vibration 
damper 90 and the turbine wheel 23 at a radial outer side of the clutch 
housing 1, i.e., at the impeller shell 11, via a weld 55. The dividing 
wall 53 divides a space 54 in which the hydrodynamic circuit 32 operates 
from a residual circuit 108 receiving the lockup clutch 84 and torsional 
vibration damper 90. The dividing wall 53 according to FIG. 1 has a very 
small cross section in the axial direction and acts as a diaphragm-like 
element 57 due to its axially elastic behavior. The dividing wall 53 
includes a bend 58 in the radial inner area. A radially inner side of the 
bend 58 contacts a holder 45 via a seal 49. The holder 45 is fastened to 
the turbine base 24 and acts as a clutch component 47 whose movement 
coincides with that of the turbine wheel 23. The dividing wall 53 is 
movable relative to the turbine wheel 23. As is shown in FIG. 1, the seal 
49 may be constructed as an elastomer seal 51 which is clamped in radially 
between the bend 58 of the dividing wall 53 and the holder 45 by natural 
deformation. As an alternative, FIG. 1a shows that the seal 49 may also be 
constructed as a sliding ring seal 35 with spring-loaded sealing means 37 
When the switching valve 70 is positioned such that the medium 106 
comprising mineral oil from the reservoir 72 flows under pressure through 
the pressure medium line 65, that is, the center bore 64 of the driven 
shaft 62, the medium 106 flows via the free end of the driven shaft 62 and 
the radial channels 78 in the axial bearing 76 into the first chamber 80 
axially between the radial flange 3 and the piston 82. In this 
arrangement, an overpressure is formed in the first chamber 80 relative to 
the second chamber 110 at the opposite side of the piston 82 thereby 
urging the piston 82 toward the hydrodynamic circuit 32 so that the 
friction facing 86 at the piston 82 at least substantially releases the 
friction surface 88 at the radial flange 3. In this position, movements 
introduced from the drive 7 are accordingly transmitted via the 
hydrodynamic circuit 32 to the turbine hub 25 and from the latter to the 
driven shaft 62. However, as soon as the position of the switching valve 
70 is moved into its other position, the medium 106 flows under pressure 
into the pressure medium line 69. In this position, the medium 106 passes 
from the supply reservoir 72 via the toothing 27 between the turbine base 
24 and turbine hub 25 into the second chamber 110 and simultaneously flows 
out of the first chamber 80 via the radial channels 78 of the axial 
bearing 76 and the pressure medium line 65 back into the supply reservoir 
72. Accordingly, an overpressure is formed in the second chamber 110 so 
that the friction facing 86 at the piston 82 is brought into an operative 
connection with the friction surface 88 at the radial flange 3. 
Consequently, regardless of the position of the switching valve 70, an 
overpressure is always formed via the medium 106 in one of the first and 
second chambers 80, 110 located within the residual circuit 108. In 
contrast, the space 54 and, in this connection, particularly the 
hydrodynamic circuit 32 is filled with a medium 104 comprising a higher 
density than that of medium 106. Referring to FIG. 1b, instead of the 
higher density of medium 104 a higher density may also be achieved by 
adding high-density solid particles 112 to a carrier fluid 111. The higher 
density fluid of medium 104 may, for example, comprise polyglycol or 
silicone oil. The carrier fluid 111 may also comprise a higher density 
fluid with additional solid particles 112 for an even higher density. 
The seal 49 between the dividing wall 53 and the clutch component 47 and at 
least one additional seal 34 associated with the seal 49 effectively 
prevent the higher-density medium 104 from exiting the space 54 when the 
clutch housing 1 is stationary. The gravitational force acting on the 
medium 104 in this operating state is not sufficient for overcoming the 
seal 49 or the additional seal 34. 
During rotation of the clutch housing 1 about the center axis 4, the medium 
104 of higher density is thrown radially outward due to centrifugal force 
thereby creating a vacuum in the radial inner area of the hydrodynamic 
circuit 32. At the same time, an overpressure occurs in the residual 
circuit 108 due to the pressure acting on the residual circuit 108 via the 
pump 74 and the medium 106 as described above. The overpressure in the 
residual circuit 108 and the vacuum pressure on the other side of the seal 
49 and the additional seals 34 causes a small leakage flow of medium 106 
to pass from the residual circuit 108 into the hydrodynamic circuit 32. 
The medium 106 which passes into the hydrodynamic circuit 32 is 
distributed radially inside of the medium 104 because of its lower density 
compared with medium 104. That is, the medium 104 is centrifuged radially 
outward relative to medium 106. Therefore, the medium 106 acts as a buffer 
fluid between the hydrodynamic circuit 32 and the residual circuit 108 in 
the radial inner area of the hydrodynamic circuit 32. 
When a relatively large slip occurs in the hydrodynamic circuit 32 between 
the impeller wheel 17 and the turbine wheel 23, the higher-density medium 
104 may heat up slightly, causing a discernible rise in pressure in the 
hydrodynamic circuit 32 and accordingly in the space 54. As soon as the 
rise in pressure causes an overpressure in the hydrodynamic circuit 32 
relative to the residual circuit 108, the medium 106 acting as buffer 
fluid is guided back again into the residual circuit 108 via the seal 49 
and seal 34 as a leakage. The overpressure in the hydrodynamic circuit 32 
is reduced by this leakage flow. A further reduction of the overpressure 
in the hydrodynamic circuit may be achieved by constructing the dividing 
wall 53 as a diaphragm-like element 57 capable of increasing the space 54 
by axial deformation and causing a relaxing of pressure. However, the seal 
49 may also be constructed as an elastomer seal 51 that is axially 
movable, so that a respective position of this elastomer seal 51 depends 
on the pressure difference between the hydrodynamic circuit 32 and the 
residual circuit 108 and is adjusted accordingly. A displacement of the 
seal 49 therefore causes a change in volume in the space 54 and 
accordingly a balancing of pressure in the hydrodynamic circuit 32. The 
seal 49 may also act as a pressure-compensating valve element 130. While 
the seal 49 may accordingly be stationary when using a dividing wall 53 as 
a diaphragm-like element 57, the alternative embodiment including a 
movable seal 49b in the construction according to FIG. 3 has a thicker and 
therefore dimensionally more stable dividing wall 53b. In the construction 
according to FIG. 3, the seal 49b is also advantageously formed with a 
spring-loaded sealing means 37b based on the arrangement of FIG. 1a, 
because this arrangement enables a precise adjustable leakage flow. 
Returning to the problem of the heating of the higher-density medium 104 
due to a large slip between the impeller wheel 17 and the turbine wheel 
23, an efficient cooling is achieved in that fresh and therefore cooled 
medium 106 constantly flows against the side of the dividing wall 53 
facing the residual circuit 108, thereby conducting heat away from the 
hydrodynamic circuit 32. 
FIG. 2 shows another embodiment of the hydraulic clutch device according to 
the present invention, like elements include the same reference number as 
FIG. 1 embodiment with a suffix "a". In contrast to the embodiment form in 
FIG. 1, FIG. 2 shows a hydraulic clutch device comprising a hydraulic 
clutch 200a having only an impeller wheel 17a and turbine wheel 23a but no 
stator wheel. To achieve good performance, a hydrodynamic circuit 32a 
formed by the impeller wheel 17a and the turbine wheel 23a is arranged in 
a radially outer circumferential area of a clutch housing 1a and encloses 
a torsional vibration damper 90a arranged in the radial center area of the 
clutch housing 1a. An input part 92a of the torsional vibration damper 90a 
is in a rotation connection via a toothing 128a with a disk or plate 124a 
arranged axially between a radial flange 3a of the clutch housing 1a and a 
piston 82a of a lockup clutch 84a. The plate 124a and carries friction 
facings 126a on both sides which may be brought into contact with the 
corresponding friction surfaces of the radial flange 3a and piston 82a. 
Pressure is supplied to a chamber 80a located axially between the radial 
flange 3a and piston 82a via through-grooves 123a radially between the 
bearing journal 5a and the driven shaft 62a and via a passage 138a. The 
driven shaft 62a has a through-bore 114a which supplies space 80a with 
medium 106a via through-groove 123a and passage 138a for lifting off the 
piston 82a away from the clutch housing 1a, and canceling the frictional 
connection between the piston 82a and the clutch housing 1a. The medium 
106a introduced into the residual circuit 108a flows through a space 110a 
radially inward and travels via radial grooves 125a in an axial bearing 
43a located axially between the turbine hub 25a and radial flange 3a 
radially inward via a radial passage 117a in the driven shaft 62a into a 
pocket bore hole 116a. The pocket bore hole 116a and an annular channel 
118a enclosing the driven shaft 62 together comprise a pressure medium 
line 69. The through-hole 114a is a pressure medium line 65a. Accordingly, 
the first and second chambers 80a and 110a of the residual circuit 108a 
receive medium 106a from a reservoir 72 (see FIG. 1) via the pressure 
medium lines 65 and 69. 
In the embodiment of FIG. 2, the hydrodynamic circuit 32a is also filled 
with a medium 104a of higher density than the medium 106a and is separated 
from the residual circuit 108a by a dividing wall 53a formed as a 
diaphragm-like element 57a. The seal 49a may comprise a stationary 
elastomer seal 51a due to the axial elasticity of the dividing wall 53a. 
FIG. 3 shows a further embodiment of a hydrodynamic clutch device 200b in 
which elements which correspond to similar elements in FIGS. 1 and 2 have 
the same reference number with a suffix "b". In FIG. 3, a dividing wall 
53b is dimensionally stable, so that, as was already mentioned, seals 49b 
may comprise either axially movable elastomer seals 51b or seals with 
spring-loaded scaling means 37b. In either case, since the dividing wall 
53b lacks the possibility of pressure compensation through its own 
deformation, the seal 49b acts as a valve element 130b between the 
hydrodynamic circuit 32b and the residual circuit 108b. In connection with 
this embodiment form, it should also be noted that the dividing wall 53b 
which is fixedly connected via a weld 55b with the clutch housing 1b in 
the radial outer area of the clutch housing 1b, is also in a meshed 
engagement by meshing 129 with the piston 82b to secure the piston 82b 
against rotation in its circumferential area. Further, it should be 
mentioned that the plate 124b is connected with the input part 92b of the 
torsional vibration damper 90b so as to be fixed with respect to rotation 
relative to it. The output part 103b of the torsional vibration damper 90b 
is connected, via a toothing, with the turbine hub 25b so as to be fixed 
with respect to rotation relative to it. 
FIG. 4 shows yet further embodiment of hydrodynamic clutch device 200c in 
which elements which correspond to similar elements in FIGS. 1, 2 and 3 
have the same reference number with a suffix "c". FIG. 4 shows the 
construction of the hydrodynamic circuit 32c in the radial center area of 
a clutch housing 1c. While this is disadvantageous for the torque 
absorption of this circuit 32c compared with the embodiments according to 
FIG. 2 or 3, it is acceptable particularly when the hydrodynamic circuit 
32c is loaded only briefly, for example, when starting, and is otherwise 
driven with a closed lockup clutch 84c while bypassing the hydrodynamic 
circuit 32c. The advantage of the construction according to FIG. 4 is that 
the torsional vibration damper 90c is shifted radially outward, so that a 
very large spring volume is achieved and torsional vibrations may be 
effectively cushioned when the lockup clutch 84c is closed. In the present 
case, the input part 92c of the torsional vibration damper 90c is 
connected, via a toothing 128c, with the plate 124c of the lockup clutch 
84c, while the output part 103c engages, via a toothing 136c, at the 
turbine base 24c of the turbine wheel 23c so as to be fixed with respect 
to rotation relative to it. Further, the turbine base 24c receives two 
elastomer seals 51c of seal 49c. One of the elastomer seals 51c contacts 
the impeller hub 11 and the other elastomer seal 51c contacts a bend 58c 
at the radially inner end of the dividing wall 53c between the 
hydrodynamic circuit 32c and the residual circuit 108c. The dividing wall 
53c is also constructed as a diaphragm-like element 57c again in this case 
and can accordingly provide for pressure compensation. Consequently, it is 
possible to use stationary elastomer seals 51c in the seal 49c. 
The invention is not limited by the embodiments described above which are 
presented as examples only but can be modified in various ways within the 
scope of protection defined by the appended patent claims.