Note: Descriptions are shown in the official language in which they were submitted.
lO~S933
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The invention relates to a variable power transmission
device for motor vehicles fitted with a multi-stage mechanical
gear change.
Conventionally such power transmission devices include
speed-change gear wheels in the form of pinion gears and, in
order to change gears, clutch couplings associated with the
pinion gears are actuated under the control of a gear selector
lever, via a mechanical linkage. The use of synchronization
devices for the clutch couplings has certainly rendered unneces-
sary laborious double-declutching when changing down through the
gears. However, to achieve synchronization of the clutch
couplings, the drive connections need a certain amount of "gear-
change time" and if a driver disregards the "gear-change time"
and "crashes through" the gears, the inevitable result will be
not only rapid wear of the geaxs and synchronization device,
but also early failure or breakdown of the gears and the device.
In the case of vehicle transmissions used in conjunction with
hydrodynamic torque converters, compound gear boxes are known
which are constructed as planetary gearsj assembled from severaI
sets of epicyclic gears. In such a transmission, changing from
one speed to another is carried out with the aid of servo-
actuated brakes and/or couplings by means of which one of three
drive elements is stopped or separate drive elements connected
together. In order to obtain a sufficient number of gear stages,
which is particularly important for heavy trucks and buses and
e~ven more important for ear~h-moving vehicles, this type of
compound gearing is very expensive and cumbersome due to the
number of gear sets required. Further, for satisfactory operation
of gear changes compound gearing requires complicated controls
which increase the likelihood of breakdown, and also requires
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considerable "gear-change time". In addition, fluid pumps
with high output are necessary for the controls because motors
incorporated in such transmissions generally operate with rotary
seals which do not allow high pressures to be used and which
possess inherent high losses due to leakage.
It is therefore, an object of the present invention to
create a power transmlssion device for vehicles fitted with a
multi stage mechanical gear-change which can be used both in
conventional manner without a torque converter and also in
conjunction with a torque converter, with simple and reliable
construction and the least possible loss, and which allows the
shortest possible "gear-change time" both when changing up and
when changing down through the gears.
- According to the present invention there is provided:
A variable power transmission device for motor vehicles fitted
with a multi-stage mechanical gear change wherein the gear change
includes planetary gearing with at least two epicyclic gear
sections of different diameters and with associated drive components
which can be frictionally braked or coupled into a drive line,
each brake or coupling having an associated servo-motor for
actuating the same and each servo-motor having a non-rotatable
housing, a multi-position control valve in circuit with a
pressure fluid system for selectively controlling operation of
indivldual brakes and couplings and a low capacity hiyh pressure
pump for holding the brakes, and couplings, the low cauacity
high pressure pump being connected in circuit between the fluid
system and the control valve and a non-return valve which is
connected in parallel with the low-capacity high pressure pump
and which opens when a servo-motor is filled.
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The use of a planetary gear according to the invention and
including at least two epicyclic gear sections of different
diameter and associated drive components which can be frictionally
br.aked and/or coupled (for which all braking and coupling is
actuated using servo-motors having non-rotatable housings) enables
a transmission to be made having comearatively small overall
dimensions. Furtherm~re, the use of non-rotatable housings
considerably reduces sealing problems in the servo motors thereby
reducing, if not eliminating, the usual leakage losses. This
invention has an advantage in that it allows the servo motors
to be connected through a selectively opening multi-position
control valve to an.existing pressure.fluid system (such as,.
the lubricating medium system of the drive motor or the filling
pump of a hydrodynamic torque converter) which supplies only that
quantity of pressure fluid which is re~uired to fill the servo
motor which is connected at any particular time, whereas a
supplementary high pressure pump produces the holding pressure
necessary for the satisfactory engagement of.the friction-contact-
brakes and.couplings after the fillingtprocess. In this respect
the non-return valve which.is connected is parallel with the
high pressure pump, automatically controls the amount of pressure
fluid required to fill the servo motors, in that it opens against
a counter pressure which remains low during filling and after
filling, shuts off the back-flow of the servo motors which are
provided with the holding pressure by the high pressure pump.
Thus, owing to the use of non-rotatable servo motors and the
consequent easily solved sealing problems permitting low capacity
servo motors to be used, the high pressure pump need only compensate
for small leakage losses. It will, therefore, be appreciated that
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1075933
in th~s way a power transmission.device.is created which is of
simple construction and of compact dimensions and which can
be,used to advantage both in vehicles without automatic trans-'
mission and with automatic transmîs'sions, in particular with a
hydrodynamic torque converter operating without steps. Furt,her,
the pressure .fluid 'control.of the gear change device according
to the in'vention permitstlocation thereof in.many different -,
positions and at the same time allows a manufacturer considerable, ' '
'freedom.for the construction of.the control itself, irrespective
of whether the selection of the speeds is carried out by hand
or depending on different parameters of the power transmission
device, such as the ratio between'the number of revolutions
of the drive input shaft and that of the output shaft, the
turning moment requirement or some other parameter.
It is a feature of this invention that each servo motor
is connected to a pressure-free return duct via its own maximum :
pressure valve which is pre-set to operate at its own individual
and characterlstic opening pressure. ~his feature allows the
establi.shment of the connecting pressure-~on the one hand and
holding pressure on the other hand of each of the servo motors ~'
to be maintained'at an optimum value even with the use of a
common hydraulic system and a common high-pressure,holding
pump for all the servo motors. This facility can be further
improved by incorporating means for individually adjusting the
opening pressure of the maximum pressure valves. Due to tl-e
small capacity of the.high pressure holding pump, the removal
of small amounts of fluid is sufficient for effective pressure
limitation so that the maximum pressure valves can be constructed
correspondingly small.
In many cases, the use of plane,tary gears with drive
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1075933
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components which can be frictionally braked and/or coupled, the
use of a traditional separating coupling can be eliminated
since the function thereof has been assumed by the individual
brakes and coupl'ings. In many instances, however, it may be
desirabie 'for'the brakes and couplings of the planetary gears
to be connected without a load for which, according to another
feature of the invention, a separating coupling is included in
a known way between the drive motor and the planetary gears.
As has already been mentioned, the invention can be applied
advantageously ~o conventional power transmission devices with
the exclusion of a multi-stage mechanical gear changing device.
However, it is a particular feature of the invention that the
planetary gear of the invention is used in conjunction with
a hydrodynamic torque converter and in such a case the torque
converter is arranged between the drive motor and the planetary
gear. In such a case, it may be desirable to connect the brakes
and coupling of the planetary gears when the former are not under
load and this may be achieved using a separating coupling disposed
outside the planetary gears. However~ it is particular~y
advantageous if the torque converter has a releasable torque
transmitting bladed component (e.g. pump or turbine) which
transmits the moment and forms the actual separating coupling.
This releasable pump or turbine component can be connected
or released from an associated shaft in a known way by reversing
the flow of the hydraulic fluid through the torroidal-shaped
working chamber of the torque converter chamber via a friction
coupling. In order to disconnect the converter under normal
driving conditions, an additional direct drive coupling can be
provided for by-passing the converter and coupled expediently '
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, i07S933
to a release device for the torque-transmitting bladed component
in s'uch a way that the torque converter is made inoperative
when the direct drive coupling is imposed, i.e. the circulation
of fluid in the torroidal-shaped converter chamber is brought
to a standstill. This can also be achi$ved by releasing the
torque-transmitting bladed component of the converter at the
desired rotation when the direct coupling is connected.
As already mentioned, the power transmission device according
to the invention is suitable Eor vehicles without automatic
the
transmission, in which therefore,~changing gear is controlled
manually. In such cases, and according to another feature of
the invention, the multi-position control valve can be manually
operated by means of a lever which runs in a slideway, which
preferably includes a neutral position track with'finger-shaped
tracks branching out from it for the individual connecting
positions of the mechanical gear changing device. If desired
and, in conjunction with an additional separating coupling
(which may be in the form of a separate coupling or a releasable
converter impeller component), the lever can further be fitted
wlth a connecting device for operating the separating coupling
-in such a way that this opens when'the lever is in the neutral
position track. This arrangement can be still further improved
when used in conjunction with a hydrodynamic torque converter
which can be by-passed by a direct drive coupling by connecting
in hydraulic drive over part of the finger-shaped tracks adjoining
the ncutral position track, and by connecting in dircct drive
over at least part of these tracks in the subsequent terminal
area. In this arrangement, the positive connection of the
hydrodynamic torque converter at each gear change results in
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1~75933
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a smooth speed change without the hydrodyllamlc torque converter
remaining disconnected for any length of time and thereby
reducing the operational effectiveness.
. In a power transmission device fitted with a manually
operated gear change it may also be desirable, for the optimum
exploitation of the efficiency of the engine, to carry out
automatic changes between two adjacent gears according to the
prevailing driving conditions. This can be achieved by
connecting a.change-over valve to an outlet of the multi-position
: control valve, the change-over valve serving to automatically
change gears between at least the two highest gear positions
under certain driving conditions.
The invention will now be described by way of example with
reference to the.accompanying drawings in which: .
: Figure 1 is an axial section through a drive connection
used in a first embodiment of the invention, showing a one and
a half stage hydrodynamic torque converter connected to a
planetary gearing;
Figure 2 is a diagram showing graphs of the engine speed,
in revolutions per minute and the traction power P of a vehicle
plotted against the vehicle speed in Km per hour for a drive
connection as shown in Figure 1 and in respect of the four
forward speeds obtained therewith;
Figure 3 shows the drive connection of Figure 1 in simplified
form with a hydraulic connecting device for selectively connecting
. individual servo motors Eor thc couplil-g and braking, bo~h ~or
hydraulic drive and direct drive of the hydrodynamic torque
converter, and in this simplification of the invention, the basic
pressure for the control fluid is supplied by the lubricating
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oil system of the internal combustion engine, , -
. Figure 4 is a modified version of the control syste~ of
Figure 3;
Figure 5 shows a further modification of the control
system of Figure 3, and - .
Figure 6 is an axial section taken through a drive connection
suitable for heavy vehicles and including a two-stage hydrodynamic
, torque converter and a planetary gearing.
,~ The drive connection shown in Figure 1 has a.converter
part W and a mechanical drive part M, which are enclosed by
stationary housings Hl and H2 respectively, and which are
rigidly connected to each other. In,this description "front"
, shall ~ean towards the left in Figure 1 and "rear" towards
the right therein.
The housing Hl contains a one and a half stage hydrodynamic
torque converter with a rotatable converter casing 10 which can
be driven via a coupling 12 by the flywheel 14 of. a vehicle
- epgine (not shown), particularly a diesel engine, and is mounted
. at the rear end in a bearing 16 on a hollow shaft 18. The
- converter casing 10 defines a part of the circumferentially outer
boundary of a torroidal-shaped working chamber 20 and supports
a ring of pump blades 22. The outer boundary of the torroidal-
shaped working chamber 20 is completed by a turbine wheel 24
which carries a ring of turbine blades 28 and a guide or reaction
wheel 26 which carries a ring of guide blades 30.
The guide wheel 26 is mountcd on thc hollow shaft 18 via
a freewheel 32 in such a way that the guide wheel 26 can only
rotate in the same direction as the converter casing 10. The
turbine wheel 24 is rotatably mounted on a hollow shaft 34 and
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1075933
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is sealed relative to the hollow shaf~ 18 by a sealing ring 36. -
The hollow shaft 34 carried on-a main drive shaft 40 by a spline .
. connection 38 with the splines on the shaft 34 machined to include
a plurality of. circumferentially extending grooves 38A. The
drive shaft 40 is mounted at the front end in the converter
casing at lOA and at the rear end in the housings Hl, H2 by
means of a'ball bearing 42.
The hollow shaft 34 is mounted for axial movement in the
.central main drive shaft 40 and in the turbine wheel 24 and it
is sealed during axial movement by a seal 44'10cated at the
rear end of the hollow shaft 18. At its front end, the hollow
shaft 34 carries a friction disc 46 having. a conical outer flange
46A, the outer peripheral face serving to co-operate with a
conical insert 48 on casing 10 and the inner peripheral face
thereof serving to co-operate with a conical ring 50 on the
turbine wheel 24. .The conical.ring 50 and the friction disc
46/46A together forms a coupling'F between the turbine wheel
24 and main drive shaft 40, by which the ring of turbine blades
28 can be connected to or released from the main drive shaft 40.
Further, with the conical insert 48 the friction disc 46/46A forms
a direct coupling D between the converter casing 10 and the main
drive shaft 40 when the hydrodynamic torque converter revolves.
Leaf s.prings 52, 54 carried by the converter casing 10 or on
the turbine wheel 24 respectively normaliy serve to centrali~e
'the flange 46A between the conical insert 48 and the conical
ring 50 and .thus keep both couplings F ~ D disengaged. l'hc
setting up of'the couplings.F & D is achieyed by control of the
flow of fluid into and out of the torroidal-shaped working
chamber.20. For this purpose, between the bollow shaft 34 and
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. 1075933
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,,and the central main drive sha~t 40 there is a pressure fluid
channel 56 through which'converter fluid under pressure can be
supplied by.a filling system ~not shown in Figure 1), via a
transverse supply bore 58 and through to the front side (i.e.
left hand side as viewed of Figure 1) of friction disc 46.
In a similar way, between the hollow shaft 34 and the hollow
shaft 18 a channel 60 connects a.supply bore 62 from which
converter, fluid under pressure can be introduced via the axial -
..... ...passages 64 in bearing 66, bel:ween the hollow shaft 34 and the
turbine.wheel 24 to the rear side (i.e. right hand side as
viewed in Figure 1) of the friction disc 46. In the turbine
wheel 24 there is a first maximum pressure valve.68 which opens
into the space formed between the turbine wheel 24 and the
friction disc 46 when a certain pressure is reached in the
converter chamber 20. ~ ,
A second maximum pressure valve 70 is located in th,e
friction disc 46 and opens when a certain pressure is reached
in the space between the turbine whee.l 24 and the friction disc
46, this space being.then connected to the channel 56. The
' hollow shaft 18 has on its outer side'a channel 72 through
which the torroidal-shaped working chamber 2~ can be connected
to a supply 74.'
" ' It will be understood.that when fluid under pressure
is introduced through the supp,ly bore 58 and the channel 56
to the front side of the friction disç 46, a pressure force -,
' will be exerted which presses disc 46 against the turbine wheel t
24 and thus engages the coupling F. When this coupling F
engages, the pressure fluid is prevented from directly flowing
into the space between the converter disc 46 and the turbine wheel , r
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24. The prçssure fluid which is supplied thus flowsaround the
, , periphery of the turblne wheel 24 into the "working chamber 20,
.increases the,pressure in the working'chamber and opens the
maximum pressure valve 68, so that the converter fluid returns
. through the channel 60 and the supply bore 62 to a valve of
. the pressure fluid system which will be later described. If, on
the other hand, the .pressure.fluid is passed through the supply
, bore 62 and the channel 60 into the space between the d.isc
and the turbine wheel 24, it exerts a pressure on the rear side.
,of the friction disc 46 and, by moving the friction disc 46,
forces the direct drive coupling D into engagement. Since in
this.instance the pressure fluid is prevented from flowing
away over the flange '46A of the friction disc 46 into the space
between the disc 46 and the converter casing 10 and onwards to
the channel 56.and the supply bore 58, the-maximum pressure
valve 70 opens when the necessary pressure has been reached.
In this way the valve 70 allows the pressure fluid to flow
away while at the same time maintaining an adequate pressure
difference between the twd sides of the friction disc 46.
The housing H2 is supported in a.~all bearing 76 at the
rear end of a drlve shaft i8, the front end of which is mounted
in an axial bore formed in the central main drive shaft 40. A
two part epicyclic gear unit 80 is rotationally fixed to the
drive shaft 78 at 82, and bears a number of epicyclic gears 84,
of which only one is visible in the plane of the section shown
in F'igure l. Each epicyclic gear 84 has three planet ~ears
.
86, 88, 90 with different diameters and is mounted with roller
, bearings 92, 94 outside the largest planet gear 86 or between
the planet gears 88, 90 in th`e two-part epicyclic unit 80.
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75933
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The ring and sun gears, to be described below,'may be referred
. to generically as "annular gears"~ '
A flange 96 on the end of the main drive shaft 40 is
connected by a spline connection to a drive flange 98 which is
rotationally fixedly connected to cylindrical ring gear 100
which meshes with the larges.t planet gear 86 of the epicyclic
gear unit 80. A cylind~ical sun gear 102 is rotatably and
: axially movable mounted on the drive shaft 78 and has sun .
gear rings 102A, 102B at its ends as shown. The ring gear
102A meshes.at the front end with the larqest planet gear
86 of the epicyclic gears 84 and gear ring 102B meshes at the
rear end with a friction disc 104. The friction disc 104 can be
braked by a servo motor piston 106, which is movable in the
housing H2, against the force of a p~ate spring 108 carried by
a fixed housing insert 109. The epicy.clic unit 80 has a further
. cylindrical sun gear 112 which is mounted to mesh at its front
end.with the middle planet gear 88 of the epicyclic gears and,
at its rear'.end, is rotationally fixed to a friction disc' 114,
which can be firmly braked by a servo-moebr piston 116 against
the effect of a plate spring 118 carried by the above-mentioned s
housing insert 110. A third sun gear 120 meshes over the greater '-
part of its length with the smallest planet gear 90 of the epicyclic
gears 84 and is connected at its rear end to a friction disc
122 which can be braked by a servo-motor piston 124 against
the effect of a plate spring 126 supported on an extension 127 7
of the hous'ing H2. Finally, a further ring gear 130 meshes
radially outwardly with the smallest planet gear 90 of the epicyclic 3
gears 84. The ring gear 130 is formed integrally with a friction
disc 132-which can be firmly braked by a servo-motor piston
.
134 against the effect of a plate spring 136 on a housing insert .
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128.'
The epicyclic unit 80 has an annular member 138 on which a
pressure ring 140 of a disc clutch 142 can be moved between ring
gear 100 and the epicyclic unit 80. In this unit 80, gear 100
i8 the drive annular gear. For engagement of the clutch 142,
there~is a servo-motor piston 144 which is located in the rear
area of the.houding part.tH2 and which acts via a first needle
bearing 146 on the axially movable sun gear 102 and a second
needle bearing 148, together wit'h push rod 150 acting on a movable
pressure ring 152'on the hub'of ~he epicyclic unit 80. When
moved to the left the pressure ring 152 engages a number of
radially extending levers 154'which are pivotally mounted on the
annular member l38 of the epicyclic unit 80 outside its center.
The outer ends of the levers 154 engage-the pressure ring 140 for
the operation of the disc clutch 142; A plate spring 156 located
in the region of the outer ends of the levers 154 is stressed
to.bias the levers 154 into the disengaged direction of the clutch
142 so that,.when the servo-motor piston 144 is not actuated,
the clutch 142 is disengaged and, at the-'same time, the needle
bearings'l46,.148 remain axially loaded.
'It is apparent that upon engagement of the disc clutch 142 by ''
setting the servo-motor piston 144 under pressure, a direct
connection of the main drive shaft 40 and the drive shaft 78
is achieved and this.corresponds to the fourth gear of the
mechanical drive part M formed'by the epicyclic gears. Apart
from this direction gear, a first gear, with the greatest step-down
in the gearing, can be connected by braking the sun gear 120 with
' the aid of the servo-motor 124, a second gear can be connected
.
by braking the sun gear 112 with the aid of the servo-motor 116
and a third gear can be connected by braking the sun gear 102
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107S9J3
with the aid o~ t~he servo motor 10~. If, on the othcr hand,
the annular ring gear 130 is braked.with the aid of the servo,
motor 134, thç epicyclic unit rotates backwards in relation
to the driving ring wheel 100 and reverse drive is obtained
on the.drive shaft 78.
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1075933 .
., ' ' Figure 2 is a diagram showing the development of the
. . .
engine revolutions and the traction of the vehicle at the,wheels,
against the vehicle speed for the four gears designated as I-IV. :
The reduction ratio of the epicyclic gears given by example, are
. Gear I (braking 122/124 engaged): 3.2 : 1
Gear.II (braking 114/11'6 engaged): 1.95 ': 1
Gear III (braking~104/106 engaged): 1.32 : 1
G,ear IV (ciutch 142 engaged) . 1 : 1 (Direct ~r.ive)
. . .
,- l~hen reverse gear is engaged with the aid of the brakes 132, 134
the reduction in this example is 1.8 :1.
Figure 3 shows a first.embodiment for the control of
the different couplings and brakes with the aid of a manually
: -
' operated gear.lever 160 which can be moved from a neutral position
into four forward gear positions for the gears 1, 2, 3, 4 (in
Figure 3)(and correspo~ding to I, II, III, IV in Figure 2) and ~: '
.into the reverse gear position R. A gear lever 160 acting via 5
: a push rod 162 operates a multi-position control valve 164,
which is fed with pressure fluid through a pipe 166.
Pressure fl~id in the embodimen~t of Figure 3 is obtained
from a sump 172 by means of the lubrlcating oil pump 168 of a . `~
motor vehicle engine which is schematically shown and designated ~ :
170. The oil is'sucked out of a sump 172 and is fed 'via a filter . ~-
' 174 and a non-return valve 176. Between the filter 179 and
, the non-return valve 176 a pipe 178 feeds fluid to a high'pres-
sure pump 180 of the relatively small capacity and driven by. ~,
the rotating converter casing 10 of the hydrodynamic torque
- converter. The outlet of the high pressure pump 180 is con-
. nected to the inlet pipe 166 which is connected to the multi-
position control vaLve 164. Between the inlet pipe 178 and the
outlet pipe 166 of the high pressure pump a non-return valve 18? ',
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~ 1175933
opening to the outlet pipe 166 and a maximum pressure valve 184
opening to the inlet pipe 178 are connected in parallel to one
another.
- Leading away from the mulii-position control valve 164
and connecting the pipe 166 (according to the corresponding
position of~the gear lever 160) to the servo-motors 124, 116, 106,
144 and 134, there are five pipes 1, 2, 3, 4 and R, from each of
which a branch pipe leads via an individually adjustable maximum
pressure valve MV to a pressure-free return pipe 186, which returns
to the sump 172. In Figure 3 the five individually adjustable
maximum pressure valves are bracketed together and generally
designated MV for ease of reading the Figure.
In addition to leading to the high pressure pump 180,
the pipe 178, which is under the pressure of the engine lubri-
cating oil pump 168 also leads via a filter 18g to centrally
located pressure inlet of a 5/3 way valve 190 (i.e. a 5 port,
3 position) and to two electromagnetically actuated primary
valves 192,194 Valve 190 is shown in greater detail in
` Canadian Patent No. 1,033,643. When the two primary valves 192,
194 are operated, the pressure fluid which has accumulated at
the appropriate primary valve inlet, is introduced into the
upper or lower control chamber of the 5/3 way valve, thereby
displacing the 5/3 way valve from a central position where it
shuts off the further flow of the pressure fluid into a lower or
upper position respectively. In the lower position of the 5/3
way valve 190, the pressure fluid arriving through the pipe 178
is delivered via a pipe 196 to the connection 58 on the hydro-
dynamic torque converter whereas the connection 62 is connected
via a pipe 198 with the pressure-free pipe 186, so that the
coupling F for the turbine blade ring 28 is engaged. In the upper
position of the 5/3 way valve 190, the connection62 is connected
via the pipe 198 with the pressure
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pipe 178 and on the other hand the connection 58 is connected
via the pipe 196 with the pressure-free pipe 186, so that the
direct coupling D is connected. Correspondingly, in the neutral
position both the couplings F and D are disengaged under the
effect of the leaf springs 52, 54 which centralise the riction
disc 46. ~:
As long as neither of the primary valves 192, 19
is actuated, the flow of power throug.h the hydrodynamic torque .
converter is interrupted. If the upper primary control valve
192 is actuated, then hydraulic drive is connected in by the :
coupling of the turbine blade ring to the.main drive shaft 40,
and by actuating the lower primary control valve 194 direct .
drive connection occurs when the hydrodynamic torque converter
rotates. In Figure 3 designations D and H on lines 196 and 198,
respectively accompanied by arrows indicates the direction of :
- flow of the pressure fluid for direct and hydraulic drive :
respectively.
The actuation of the primary control valves 192 and
194 is accomplished electrically under control of the gear lever
160 via a 3-position switch 200, on which the gear lever 160
acts when moved about its pivotal axis. To assist understanding, ~ :
the portion.of Figure.3 designated X shows the view of the gear .
lever taken in a direction of arrows A-A and perpendicular to . .
its pivotal axis and from the portion-X it will be seen how the .
gear lever 160-is guided in a slideway 202 with a generally
vçrtical neutral position track N, from which finger-shaped,
relatively long tracks 1, 2, 3, 4 corresponding to the four
forward gears and a shorter track R for the reverse gear extend. :
In the neutral position, i.e. as long as the gear lever is . .
located in the neutral position track N, the actuating coils of.
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1075933
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the primary control valves 192, 194 are not energised. When the
gear lever 160 is put a short distance into one of the tracks
.to 4, firstly via line Y the actuating coil of the upper primary
. valve 192 for hydraulic drive is energised, and then upon fu'rther
movement of lever 160 to the right (as in portion X of Figure 3)
line Z is connected to actuate the coil of the lower contrpl
'valve 194 for direct drive. When the lever 160 is put into the
shorter reverse track R only the actuating coil of the upper
primary valve 192 for hydraulic drive can be actuated. .
In addition, the elctro-hydraulic control system shown
also contains a'valve 204 including two valve pistons separated
from each o~her and kept at a predetermined distance by a rod .
rigidly fixed to one piston. The two valve pistons are pressed
towards the left by a compression spring acting on the right-hand
.piston. In this position a pipe 206 connected lnto the supply
74 (Fïgure l) is, in turn, connected to the pressure fluid sump,'
thus forming a direct outlet pipe to the sump for the working'
fluid contai~ed in 'the toroidal-shaped working chamber 20 of the
converter. A pipe 208 which leads from the primary control valve
192 to the upper actuation side of the 5/3 way valve 190 also ' -
leads to the valve 204 at.a position between the two pistons
thereof. In.a similar way the pipe 210 which leads from the
primary control valve 194 to the lower actuation side of the 5/3
. . wa~ valve 190 also leads to the left side of the left actuatin~
piston of the valve 204. This construction enables the valve.204
to be operated so as to interrupt the connection between the
toroidal-shaped working chamber of the converter 20 and the
sump, via the channel 72 and between the connection 74 and the
pipe 206, as well as interrupting the opening of one of the ~'
two valves 192, 194 with the aid of the manual lever 160 and the '.
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3-position switch to.connect the hydraulic drive or the direct
. . , , , , .
dri~e. ' . ' ' '
The electro-hydraulic control shown in .Figure 3
operates as follows. Assuming that the vehicle equipped with .
the drive and the controls shown in Figure 3 is stationary, with
its engine idling and with. the gear lever 160 located in the
neutral position slot N .of the slideway 202. Under these condi-
tions the lubrlcating oil pump 168 is running and supplies not
only the drive motor 170 with oil, but also pressur'izes the pipe '.
178 without the pressure fluid therein, namely oil, being able to. .
flow away. '
If the driver now'wishes.to move his vehicle' in a .
forwa~ds direction he moves the gear lever 160 out of the slot N
downwards to track 1 for gear 1. He thereby connects, via the .'
multi-position control.valve 164, the pipe 166 with servo-motor
124 (Figure .1) for the first gear, which means that the sun gear
120 is firmly braked. This.occurs when all parts of the planetary .
gearing are stationary since the friction disc 46 in the torque ~
converter W is in its central position under the influence of . .
the .two leaf springs 52, 54 and, therefore, both the.coupling F ~ .
and .the direct coupllng D are disengaged.
When the driver moves the gear lever 160 to a position :'
half-way along the track 1 of the slideway 202, the 3-position .
switch'200 closes the contact switch Y leadinq to the actuating
coil of the primary control valve 192 to open this valve. Since `. .
at the inlet side of the.valve 192 pressure builds up from the
pipe 178, this is delivered to the upper actuation side of the ~
5/3 way valve 190 and moves this to the lower position for ~ .-
hydraulic drive. In this condition oil under pressure from the ~ '!
pipe 178 flows through the 5/3 way valve 190 'to pipe 196 and ' ' J,
from-this throuqh connection 58 and channel 56 to the.front side ~ ,
- - ~ , ., ,i
of the frict~on~disc 46, thus engaging the coupling F. Engage-
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. .
ment,of the co~pling F results in the 'closure around the peri-
phery of the friction disc flange 46~, of the space between the
friction disc 4~ and the turbine wheel 24. In addition, the valve
204 also seals off the pressure release of the toroidal-shaped
worklng chamber 20 to,the sump, and pressure builds up in the
working chamber 20 until the maximum pressure valve 68 opens.
~hus, the rnaximum pressure valve 68 opens. Thus, the maximum
pres'sure valve 68, while maintait~ing a certain pressure in the
.
working chamber 20 of the converter, allows the pressure fluid
to flow back to the 5/3 way valve 190 through the channel 60,
the connection 62 and the pipe 198 and on from there through
the pressure-free pipe 186 to the sump 172. With the engagemerlt
of the coupling F the turbine blade ring 28, which is carried
along by the pump blade ring 22, initially'without circulation
of fluid in the working chamber 20, is also braked. This ini-
tiates the circulation of the fluid in the working chamber 20,
and produces a gently increasing turning moment at the turbine
wheel 24, which is transmitted via the main drive shaft 40, the
drive flanges 96 and 98 and the ring geaY 100 to the large
planet gear' 86- of the epicyclic ge'ars 84. Since the small
planet gear 90 of the epicyclic gears 84 is held stationary on
the inner,circumference of the planetary gearing by the firmly
braked-sun gear 120, the turning moment which arises at the ring
gear 100 is further increased at the drive shaft 78 which is
connected to the epicyclic gears 84 and leads to a rapid and ' -~
yet smooth moving off of the vehicle in the selected gear ~
,It is apparent that here the coupling F acts as a
separating cou~?ling, while the brake 122 has the sole function
,of a holdin'g coupling for the sun gear 120. Despite this, the 4
load on,the coupling F is minimal because at the moment when ~'
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~ - . . . .
21-
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coupling takes place, the fluid in the toroidal-shaped working
cha~ber 20'is still stationary and, therefore, there is still
no turning moment produced at the turbine wheel 24.
As soon as the vehicle has started to move, the gear
.can be changed to the next highest gear without first having to
move the gear lever 160 right up to the end of the track 1 and
thereby, by the releasing of coupling F and engaging the direct i
coupling D, connecting the direc~.drive. In practice, connec~ion
of the direct drive in gear 1 is much more likely to be quite
. . unnecessary, so that the track 1 can be made as short as the
reverse track.R to make exclusively hydraulic drive pos-sible.
The change to the next highest gear is carried out by
moving the gear lever 160 back to the neutral position' track N,
thus openi~g thè coupling F once more, and subsequently
switching the multi-position cont'rol valve still further by
moving the gear lever 160 into the next posltion in which the
sun gear 112 is rigidly braked lnstead of the sun gear 120.
A$ with the open'ing of the coupling F., the circulation of the `
flu'id in the toroidal-shaped working cham~er again increases, . '.
engagement of the brake 114 for the sun gear 112 is also achieved
without a load, and with the.entry of the gear lever 160 into
..the track 2 of.the slideway 202 the coupling F is also'engaged,
almost without loead'. In this condition, the circulating flow
once again bu.i'lds.up in the converter chamber 20 and causes the
creation of a turning momc'nt at tlle turbinc wheel 24 whicll is
carried via the coupling F, the main drive shaft 40, thc drivc
flange 98 and the annular ring gear 110 to the planetary gearing
and there transmitted, further increased, to the drive shaft 78.
If, for example, due to the vehicle encountering an
incline or perhaps a speed limitation in local traffic, the drive
~ 22- '
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speed of the vehicle produced at the change-over point of the
converter is not to be further increased, the gear lever 160
can be put into the terminal position in.the track 2 of the
slideway 202 as required, so that the coupling F is disengaged
by closing of the valve 192, and.the di~ect coupling D .is
engaged.in its place by actuation and opening the valve 194.
When the valve 194 is op~ned, the 5/3 way valve 190 is moved into
the upper terminal position and ~he pressure fluid, which builds
.. . . .
up at the inlet of the 5/3 way valve, flows through the pipe 198,
the conn.ection 6.2 and the channel 60 to the rear side of the
friction disc 46 so that the.flange 46A engages the conical
insert 48 of the converter casing 10. The seal thus created
between the friction disc flange 46A and the conical insert 48
prevents flow round the periphery of the friction disc flange
46A and leads to the building-up of pressure on the.rear side
of the friction disc 46 of the appropriate holding force for the
direct coupling D until the ~aximum pressure valve 70 opens and,
while maintaining a sufficiently.great pressure difference,
allows the pressure fluid to flow away th~rough the channel 56
and the connection 58 as well as the pipe 196 to the 5/3 way
valve 190 and further on through the pressure-free pipe 186 to
the sump 172.
If, on the other hand, the vehicle is to be accelerated
further after.reaching the.change-over or shift point in the torque
converter, the gear lever 160 is brought back into the neutral
position track N of the.slideway 202 and the multi-position
control valve 164 is brought into the next position in which the
sun gear 102 is made stationary instead of the sun gear 112.
In this condition the gear lever 160 is moved into the position
.. ~1
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1~75933
.
for hydraulic drive (i.e. into the track 3), the coupllng F is
first opened and then re-engaged so that the smallest ~eduction
.
in the planetary gearing'is introduced into the drive line and
the converter,again increases the turning moment.
A change into gear,IV is carried out in a similar way
but, instead of the braking of the sun gear 102, the direct
coupling clutch 142 in the planetary gearing is actuated. 1~7hen
the direct drive coupling is so actuated and connected, and
the gear lever 160 is in the position 4, the torque converter
again first undertakes multiplication of- the,turning moment
until the shift point is reached, whereupon the gear lever 160
is moved into the terminal position in the track 4 and the dir,ect -
drive coupling D is connected into the drive line. In this posi-
tion the entire drive connection from the converter casing lO,
which forms the input component, up to the drive shaft 78 is
then directly and mechanically connected right through the
transmission and, in this condition the hydrodynamic torque , '
converter and the planetary gearing are disconnected.
The above description of,the c~nnection o all' stages
of the planetary gearing in conjunction with hydraulic drive
in the c~nverter part W is normally only required when partic- ~ ,,
ularly high traction power,is required either for the aceeleration
of the vehicle'with a heavy,load due to the actual load carrled,
or on inclines. With more lightly loaded goods vehicles and
personnel transpor,ters, on the otller hand, one to two of the -~
intermediate gears, such as for example gears I and III, can be
omitted. Consequently, direct drive is only con'nec,ted in the
lower gears if the vehicle is to be driven for a long time in
these gears at correspondingly lower speeds in the most favorable
worki,ng range of the drive motor.
, . ,_- ' . - ,,. ............ , . . . :
.. .-24- .
a
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. It will be self-evident from the foregoing that the
connection,of the reverse gear is carried out in a similar manner. '
Since the reverse gear is connected only for short periods and
over short dist'ances, it is never necessary to engage direct
drive (with consequen~ by-passing of the hydrodynamic torque
converter) so that the track R in the slideway 202 can always
be a relatively short track.
-The'.control.system shown in Figure 4 is differen.t from .
t~hat in Figure 3 only in that, instead of the lubricating oil
. pump of the drive motor, the hydrodynamic torque converter
filling pump (reference 310 in Figure 4), produ.ces the basic
pressure for the control system. The filling pump 310 sucks
fluid out of the sump 312 of the converter. The pressure pipe
of the filling pump 310 corresponds to the pipe 178 in Figure 3 .
and is therefore also given the.reference 178. In other respects
' the control system shown in Figure 4 is'identical to that in
Figure 3, and therefore functions in the same way.
It will be understood that, as long as the multi-
position control valve 164 remains in the neutral position in
which all outlets 1 to 4 and R are closed, that a pressure ,
build-up will occur in the inlet pipe.l66 to this valve due to
operation of the filling pump 310 or operation of the lubricating
oil;pump 168 (Figur.e 3) and the.subsequently connected high
pressure,pump 180 and that the build-up is limited 'to a specific
maximum value.by.the maximum pressure valve 184. ~s soon as the
multi-position control vaIve 164 is switched,to.connect the pipe
166 with one of the controls servos for the brakes or couplings
of.the planetary gearing, the pressure will momentarily drop and t
with the rotation of the high pressure pump 180, the.filling ~i
..
pump 310 or the lubricating oil pump 168, pressure fluid is ~
.- . ii
. ., .,,, :. ............... , ..... . ~
f ' Z S _ _
.
1075933
.. . ... . . . ..
supplied under comparatively low pressure through the non-return .. :
valve 182 directly to the servo-motor to which it is connected.
The so connected servo-motor is, therefore, rapidly filled by
virtue of the high capacity of the filling or lubricating oil .
pump, and the relevant brake or coupling is rapidly engaged with
comparatively low power. As soon as this.filling is.completed
and when, therefore, no further fluid replenishment is required
by the filllng or lubricating oil pump through the.non-return
valve 182 and the pipe'166,.the pressure in the pipe 166 rises
again and aloses the' non-return valve 182. This allows the high
pressure pump 180 to still further increase the pressure in the
pipe 166 and provides the ultimate pressure required to hold . .
the brakes and couplings in engagement.
The level of this pressure is finally individually
limited'by the maximum pressure valves MV associated with
. each individual servo-motor and.the individual valves are ad- -
. .
justed so that the as-sociated.servo-motor operates at the pres-
sure.required to hold the relevant brake or coupling.
The control system as shown in-~Figure S differs from that.
. shown in Figure 4 only in that'the multi-position control valve ~.
'. 164 has four outlets, and the.slideway has only three forward -~
' tracks 1, 2 and 3. In the position 3 the pipe 166 is co~nected
by a pipe 313 to a change-over valve 314 which is constructed as
: a 4/2 way valve, i.e. a 4 port, 2 position valve. The two
" outlets of tlle cl~ange-ovcr valvc 314.le~d to the s.crvo-motors
' 106 and 124 for gears III and IV (Figure'l), and the other
inlet of the valve 314 is connected to the torque converter sump.
.With the switching over of the valve, which can be
,
carried out electrically, hydraulically or pneumatically depending ' ' ~!
on certain parameters such as, for example, the number of
.revolutions of the engine or perhaps the position of the acceler- ' ~ :
. ~-26- . -
iO7S933
.
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ator pedal, in position 3 of the multi-position control valve . . '
164 either the servo-motor 106 is connected to the pressure ..
pipe 166 and the servo-motor 124 released (gear III) or, the
servo-motor 124 is connected to the pressure pipe 166 and the
servo-motor 106 released (gear IV). With the aid of this
.. . . ..
change-over valve the driver can, for example, sometimes be
spared from changing the'position of the gear lever 160 when
a reduction in the speed makes travel in gear III instead of
gear IV desirable with regard to the efficiency of the engine.
Further, at higher travelling speeds, a.higher turning moment
can momentarily be made available by-pressing the accelerator
pedal right down to.produce so-called "kick down".
The description of the control system according to
Figures 3 to 5 is carried out in conj~nction with the drive
connection shown in Figure 1, the torque converter part W of
which contains a one and a half stage hydrodynamic torque con-
verter with release coupling for the turbine and with direct
coupling, which can be connected alternately. It will be
apparent, however, that the control systems shown and described
-can be used in conjunction with other drive.connections which,
for example, have only one mechanical drive in conjunction with
a separating coupling of conventional design, which is open when
the gear lever 160 is in the neutral position track. In this
case, naturally the whole valve complex which is encircled in
dashes in Figures 3, 4 and 5, is replaced by a simple actuation
valve for the separating coup.ling, which can if desired, also be
çhanged electromagnetically by a switch operated by the gear
lever, similar to the 3-position.switch 200.
The control systems shown and described can, however,
r
also easily be adapted to drive connections with other hydro-. 13
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107~933
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dynamic'torque converters, which do not contain any releasable '-
bladed component. Such a drive connection is shown in Figure 6
and, although the mechanical gear M is the same as that of the
drive connection of Figure 1, the torque converter of the
drive shown in Figure 6 contains a two-stage hydrodynamic torque
converter with a direct coupling D between the converter housing
416, which forms'the input component and a maln drive shaft 48
which corresponds to the main drive shaft 40 in Figure 1, A
turbine w~eel 420 having two turbine blade' rings Tl and T2
is non-rotatably carried by the drive shaft 418 and a ring of
guide blades L is disposed between the turbine rings Tl and T2.
The guide ring L is supported on an impeller wheel 422 which,
in turn, is supported on an impeller wheel shaft 424 which is
rotatably mounted in the converter housing and encloses the main
drive shaft 418 as a hollow shaft. A multiple disc brake 426
enables the impeller wheel 422/shaft 424 to be locked with the
non-rotatable housing.
'Due to the lack of a release coupling as well as a
special spearating coupling, in the drivè connection shown in
Figure 6 the braking or coupling of thè individual parts of the
planetary gearing is carried out under load. Thus the brake
and the direct coupling operate not only as holding couplings,
but also as separating couplings or clutches and, consequ~ntly,'
are generally constructed with more braking and coupling discs. .'
~ certain amount of rellcf for these brakes and this coupling
during a change can, however, be achieved by releasing the
impeller wheel brake 416 during the change-over process so that
the hydrodynamic torgue converter does not bear the full turning
moment.
The adaptation of the control systems shown in Figures 3
to 5~can then be achieved in that the gear lever 160 is equipped
' ' ` '-28- -
1075933 :-
with a 3-position switch which in the position H opens a valv.e
.
to connect the servo-mo~or of the impeller wheel brake 426 and .
in the position D opens a further valve through which the front
face of an actuating piston 428 for the direct coupling D formed
as a disc clutch is supplied.
Although the invention has been described in considerable
detail with respect to preferred embodiments thereof, it will
be apparent that the invention is capable.of numerous modifica-
tions and variations apparent to those skilled in the art, without
departing from the spirit and SCQpe of the invention, as defined
in the claims.
'
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