CA1040509A - Hydrodynamic torque converters - Google Patents

Abstract

ABSTRACT OF DISCLOSURE

This invention relates to hydrodynamic torque converters and to torque converter blade systems. A
torque converter in accordance with the invention is particularly suitable for transmissions for vehicles where a more or less distinct top speed is required even when direct drive is not used and where it is important to avoid the simultaneous existence of high torque absorption and low efficiency at high speed ratios.
The blade system is characterised by a range of ratios for the radii of the outlet and inlet edges of pump, turbine and guide blades as well as a range of angles .alpha., .beta., ? and ? as herein defined on pages 20 and 21 of the Specification and set out in a tabular form on page 23 of the Specification.

Description

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' . .This invcntion relates to hydrodynalllic torque - converters and especially to a torque converter blade ~:~ system ~hich afIords improved input torque and effi.ciency characteristics when compared with known torque converter blade systems The torque converter of the invention - is particularly suitable for use in transmissions for .~ vehicles, where a more or less distinct top speed is - ~ . required even when direct drive is not used and where j - it is important to avoid the simultaneous e~is-tence of :~ high torque absorption and low cfficiency at high speed ra.tios, The invention is a:lso applicable to very :I.arge . torque converters in which a one-~Yay c'lulch cannot bc .. used for releasing a ring of guide blades but, never-: j theless, necessitating the use of a lock-up clu-tch ~ Where the use of a one-way clutch on the guide ring is '~ advisable, the characteristic features of a torque ;~ oonverter according to the inven-tion are such that -the :
free wheel operates under especial].y favourable conditions : It is characteristic of hydrodynamic torque COII-:~. ' verters that the exten-t to which the input torque is ~ ~ 'increased or multlplied by the converter is greatest at/o.r~t~3 .'. to stall condition, that is, with the p~mlp member op~r-ating and with the twrbine member standing still. As the .: speed (n2)of the turbine member rises from zero relative to. the speed (nl) of the pump the torque multipli~atiol3 . usually referred to as the torque ratio, decreases, and :.~1 . ' .

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at some value of the ratio n2/nl less than unity, the value of the output torque falls to that of the input torque. When this point, con~only referred to as the shift point, is reached the apparatus no longel functions as a torque multiplying device and,if the speed of the turbine rne~ber is increased to produce a higher value of -' n2~ 1 than that at the shift point, the output torque falls to a value less than that of the input torque, so that the apparatus has no utility. Thus the useful ra~ge of a hydrodynamic torque converter is ilormally between stall and shift point.
Generally speaking torque converters fall into one o~ two main types, namely a 1 1/2-stage type or a 2-stage type In the 1 1/2-stage type the torque con-verter blade system has only one ring of pump blades, ~'- ' one ring of turbine blades and one ring of guide blades whereas the 2-stage type has one ring of pump blades~ two rings of turbine blades Wi't}'l one intermediate ring of guide ''-blades. However, many variants.of these two main type .i . .
; of to'rque converter blade systems have been proposed including blade systems having a divided guide blade 'ring and/or large nwllbers o~ rings of turbine blades and/or'rings of guide blades and even a divided pump ring ' The present invention is particularly but not `' : I .

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1 ~ ~)4~SQ9 exciusiYe~y dirccted to a torque converter blade systcm of thc l l/2-stage type wherein the ring oE guide blades is located in the torque converter working chamber in a position (considered rela-tive to the direction of fluicl flow within the ~rorking chamber) immediately before the inle-t of the pump blades. The working chamber may be formed with many different cross-sectional shapes such as circular, half-circular, or pear-shaped, etc.~
A torque converter blade system according to the invention influences the fluid circulation in the blade system by virtue of novel and specific blade shape so that, when the so-called shift~point is reached, the circulation of *luid in the blade system rapidly di~nini.she~.
~apid diminution of the fluid circula-tion results in not only a reduction in the torque absorption but also a simultaneous reduction :in the e~ficiency thereby avoiding, ." ..
when the torque converter lS running above the shift point, a high torque absorption and low efficiency since under such running conditions mechanical energy is simply converted into heat.
One known method of avoiding the above is the use of a free wheel on the guide vane shaf-t so that, when the pump and turbine are rotated at the same speed, there is no force crcating flui.d circulation within the working chamber. The.torque absorption of the blade system is, therefore, low and depends primarily on the torque necessary ~ .
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. ~ to ~Irive the frec wheel. At speed ra-tios bet~Yeen the ~:~ shi~t point and n2/nl = 1 the guide blades are free , ~ wheeling and the torque converter operates as a coupling : with the torque absorption related to n1 and to (n2/n1)~
; . The existence of a free wheel in the torque convertcr invariabl~ causes problems because it is required to ; function normally, whilst running in oil,both during connection . and ~hen free-wheeling at high speed Moreover, the free .. .
.j wheel is located in a space co~pletely filled with oil having .
. a viscosity which may vary over a wide range due pri~arily . to the variatlon in temperature ~ithin the working chamber. .
: A wide variation in the viscosity cons:ideral)ly reduces the safely li.mits of the frictioll force required to locl~ thc : free wheel. The temperatu:re o~ the fluid in the working chamber .:
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: : may be within the range -4iOC up to ~k50C, and in spite of :' such a wide temperature range it is not unusual -for di~er-: ent oils between SAE 5 and SAE 20 or even SAE 30 to be used .. The blade system of the present invention provides apar-t.
. fro~ speci~ic new char~ctcristics, an extre1uely hi.gh peal~
. efficiency in relation to the stall torque ratio ob-tained . as well as provid:ing favourable input torque characteristics .
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.: The blade system o-~ the invention allolYs a torque :~ converter incorporating a lock-up clutch to also include ^, a stationary ring o~ guide blades without producing .

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iL(~4~S~9 excessi.ve losses in direct drive In -fact sucll a converter only produces abo~lt 2% losses considered in re].ation to full input power at stall and nl maximum l.rhereas a loss of the order o~ 1% can be expected when the ring o-f guide biades is.mounted on a free wheel Simultaneously, it should be borne in mind that the free wheel is the weal~est point in such torque converters in that it is the only component ~r~ich causes trouble.
Tpus elimination o~ the free wheel, even in the normal power range ~or heavy duty service is of utmost interest, and more particular].y in cases where the torque converter incl~udes the power saving lock-up clutch in conjlmction with a mu]ti-step gear box.
Furthermore, relatively large torque converters require large ~ree wheels which are not generally available o~f-the.-shel~ and must, therefore, be~ e~e made~thereby increasing the cost of the torque converter. In such applications the loss of an extra 1% in direct drive when elimina.ting the free wheel is less important, especially when a manufacturer or user can completcly ignore the cost and avai.lability o-f the free wheel uni-ts.
In applications where a ~ree whcel is desirablc, the conditions, under which the free wheel operates are improved, because -the normal drag torque o-f the free wheel using a blade system according to the invenlion ls sufficient to . .' ,' J

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~ 9 reduce the speed ol rotation of the ring of guide blades to 25% Of the speed of the rings of -the pump and the turbine blades. Thus,-the loss is in fact lower than the normal percentage loss and, simultaneously, wear on the free wheel is reduced by virtue of the reduction in relative speeds.
In applications where a torque converter according to the invention with or without direct drive i~s combined with a ~echanical gear box, a transmission is obtained which does not necessarily require automatic shifts because there is no possibility to run at high speed ratios with low efficiency and high torque absorption. Insuch cases it is not necessary to effect a shirt into a higher gear at a distinct point It does not mal;ter, thereforc~ if the drlver eEfects a shif-t too late because a labe ~hift will neither create overheatlng or increased fuel consumption In fact, for an application, where direct drive will not be used, there is obtained for the first time not only a distinct top speed in each gear but also the advantage that driving undcr unacceptable conclitions is not possible SUMM~RY OF T~ INVENTION
~ ccorcling to tile present invention -the abo~re Ieatures are a¢hieved by a blade system of such a form that (abo~re a certain speed ratio which is only a little higher than the shift point and for speed ratios higher than this value) different quantities of circulation of fluid through the blade system produce practically no change in the direction of fluid flow through the guide blades 1~hereby, at loclc-up, l 7 ~ .'' ' ' ''' .'' ' " ',.
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. .,. :, ~4~S~!9 where the pump and the turbine rotate at the same speed, the guide blades may rotate slowly or be stationary -thereby reducing agitation of the worlcing fluid because -the drag torque of the guide blades will not, ol i-tsèlf, con-tribute to but will counteract fluid circulati~n. When the guide blades are stationary in conditions above the shift point, the guide blades operate to balance the pumping e-ffect of the pump blades relative to the turbine blades in such a way that a low fluid circulation prevails through the blade system, s~ as to achieve a low torque absorption.
It is important that the fluid circulation is achieved within a small change of speed ratio and the test diagrams hereinafter described show that this is the case. The reason is that the inLet direction to the guide b:lade changes quickly in the range close to the shift point, since with a constant fluid quantity (which is counteracted by reduction in fluid circulation) the quantity of fluid circulated drops quickly due -to the shape of the blade system according to the invention to values giving a torque absorption of the pump as shown in ~igures 2 and 3.
Description of the Drawings.
The invention wil:l be descrLbed by way of example with reference to the accompanying drawings in which:-Figure 1 is a cross-section of a torque converter having a ring of stationary guide blades and a blade system according to the inven-tion;

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~ - ~ Figures 2 ancl ~ are graphs sllowing the performance i of the torque converter according to Figure 1 and Wi th ,1 ~ the blade sys-tem construc-ted and arranged for a rela-tively : :.
high torque absorption characteristic;
Figures 3 and 3A are graphs showing the perIormance o~ the torque converter according to Figure 1 and with .
, the blade system constructed and arranged for a low ' torque absorption charac-teristic;
Figure 4 is a cross-section of a torque converter ~hich is similar to the torque converter of Figure 1 but modi~ied to inclucle a lock-up clutch and a releasable turbine torquc transmitting member as disclosed in our , Britisll Patent No. 1~41~1,6~
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; Fi~ures 5 and 5A arc ~rnphs showing the per~ormance '!`: of the torque converter o~ Figure 4 having the blade system o~ the invention with a ring of guide blades ~ounted on a one-way free wheel, , Figures 6 and 6A are graphs showing thc same per~ormance curves as in Figure 5 but for a torque converter having a low torque absorp-tion;
Figure 7 S}IOWS a torque convcrter which is the same as that of Fig~re 4 e~cept that the ring of guide blades is not mounted on a free wheel even though the converter ,~, has a lock-up clutch. With this blade syste~ the torque absorption of the torque converter has the same perform-.~ , . .
~ ance characteristics as shown in Figure 5 and 5A.

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1 Figure 8 shows grapllically the losses experienced .. 3 ` in a torque converter having tlle blade system of the . ~ . .
~¦ invention when in dircct drive I'irstly with and secondly without free wheel for the ring o~ guide blades.
, Figure 9 is a cross-section of the working chamber, ., in ~Yhich the blade sys-tem is mounted. I-lowever, the shape of ~he cross-section itself is not essential for carrying out ¦ the invention. The blade system in question, however, ~;l is ~avourable in itsel:E and ~as mounted in such a wor~ing cha~ber for the purpose of tests, the results of which ~ tests are included in this specification.
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Figures lOA, 10~ and lOC show diagramlllatioal:Ly the blade shapes and their location in the rcspective blade ~-~ rings and partlcularLy diEferent blade angles and the , ~ r~ tq~/e-radius given in the~b~e inc:luded hereinaEter.
J Figures llA and llB show a preferred shape of a ¦ turbine and a guide blade respectively.
,.1 i Figurc 12 shows -the shape o:E a pump b]ade for a ;~, blade system having a high torque absorption withou-t f adversely influencing the specific performance ;characteristics shown in the ~igures 2, 3, 5, 6 and 8.
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T11e torque converter o:f`l~igure l includes a so--calletl l.l/2-stage blade system in its simplest form il and as previously mentioned ~Iowever, when the torque~
converter is fitted with a blade system according to .~ the invention, the specific characteristics represented graphically in Figures 2, 2a, 3 and 3a are obtained.
In ~igure l reference 2 is a stationary abutment to which a guide blade hub 4 is attached and on which a part 6 of a rotatable casing is mounted on a bearing 8, The rotatable casing part 6 also has a fron-t part .. 12 an.d, -from the~drawing, it will be seen that a ring :.
;, of pUlllp bla~les iS carried by the part 6 whereas the ~uide blade hub 1~ carries a rlng of gu:ide b].ades 16.
The inner ends of the pu~lp antl gl1ide blades are supported - lr~ o? ~n o~ ~ ~ r es~a e c 7~ i v ~ J
on side rings~ which form a part o~ an inner core. The stationary abut~ent 2 is journalled through a bearing 22 onto~a turbine shaft 24 and, in turn, the shaft 24 is also ~.ournalled in -the front part 12 of the rotatable casing by a plane bearing 26.
turbi.ne hllb 28 carrying the turbine blades 30 which are associated with an inner core part ~2 is also carried . on the turbine shaft 24.
Circulation of working -fluid and maintenance of the pressure thereo-f in th~ working chamber is accomplished bet~Yeen channels 34 and 44 in the stationary abutment 2, ' .,1' . 11 .~ ~
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via channels 36, 38 and 40 in the turbine shaft 24, and via return passages formed between the parts 2, 4 and the parts 28, 24. Circulation of the fluid through the working chamber may be from channel 34 to channel 44 or vice versa. The rotatable casing 6, 12 is normally driven by a fly-wheel 46 via an axially slidable, torsionally and substantially stiff coupling 48. The actual form of blades in the blade system according to the invention is shown in Figures lOA, lOB and lOC, for pump blades 14, turbine blades 30 and guide blades 16 respectively.
Figure 2A shows the stall torque ration (STR) of a torque converter having a blade system designed for a relatively high torque absorption with the pump blades having their outlet edges disposed on a fairly large diameter and with the outlet in radial or positive direction relative to the pump movement.
It will be observed from Figure 2 that a shift point of n2/nl =
0.835 is achieved and that at a shift point of 0.865 the torque absorption (M) has fallen to a value which is about 5-6% of the torque absorption at stall. At a shift point slightly above 0.9 it will be seen that the torque absorption has fallen to 1.4%
of the torque absorption at stall and less than 2% of the torque absorption at maximum efficiency. It is to be noted that, even if the torque oonverter is Eitted with a free , ~

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wheel, the torqllo absorption will be at least half this val~e at 1 : 1 in speed ratio l?urther, it is to be noted that the peak efficiency of the blade syste1n is,in its machined forlu or dye-cast ~orl~ above 90/0 eYen ~or a small blade system having a diameter of below 250mm.
Further, for the high torque absorption in question a fairly high stall torque ratio for this type of torque converter of about 2 3 is achieved and further,that the stall torque ratio is very stable for diflerent input speeds (Figure 2~). A further advantage ~of the systcm is that the primary torque developed below the shift point is favourable having a relatively high ratio bet~een :
torque at maxilllum point and torque a-t shift point of abou~ 1.5~ and is cspccially s~litable ~or aQhieving ~laximu~
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acceleration in norma~S4_u4~Y4 vehicl~ application.
Figure 3 sho~s that for the blade syste~l in question but ~or a lower torqu~ absorption the same high peak efficiency and stall torque ratio is obtained and that the specific characteristlcs of the torque absorption and efficiency above a certain point is still achieved.
On bo-th graphs it is seen that the efficien~y stays above 70% until the torque absorption has dropped to a very low value.
When a torque converter according to Figure 1 having a blade system providing the characteristics of Figures

2 and 3 is used in, for instance, a lift truck, two :' . , -' ~ ' , . , .
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; ~ di~ferent and i~uportant features will be achieved when `- compared wi-th e~isting torque converters of the ~; simple 1.1/2-stage type without free wheel. The two ., features are a distinct top speed for a certain engine speed and the impossibility to operate under part load at such a high speed ratio that the mechanical energy is nearly all converted into heat. The last ~ entioned feature has the advantage that transmission :
will ~nly require a very small cooling capacity thereby reducing the fuel consumption and fulfilling, without extra arrangements, the limited top speed requirement.
This, as Illentioned above, is achieved without a free !l wheel lor the ring of guide blades.
Figure ~ ShOlYS a torque converter and blade systcm ; similar to that of ~igure 1 but modified to include an ' ~n 1)'5' ~f~ " 3,83~ Y/!3 B arrangemen-t (described in~ t ~ ) allowing lock-up of the turbine shaft to the rotatable casing and,less importan-t in this specific case, the ; possibility of releasing the ring o~ turbine blades from the turbine shaft. Such a release possibility enables , .... .
a positive neutral to be obtained and thereby renders unnecessary any other types of disconnection on the secondary side for most fields of application. In the embodiment of Figure ~ a stationary abutment, here designated 102~ has a tubular extension 104 on which a guide blade hub 106 and a free whcel 108 are moullted thereby allowing the guide blade hub (and conse(luently . . ' " ~ .
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~l,04~)5Q9 the guide blades) to rotate ln the same direction of rotation as the rotatable casing 6, but not allowing rotation in the opposite direction. The bladed components, the inner core, the bearings and the shafts are constructed and mounted ln the same way as in :
the embodiment of Figure 1. The modification inc].udes an exten-~ sion 110 carried by the turbine shaft 24 and to which a ring of .~ turbine blades 112 can be connected and disconnected by a conical . friction clutch 114. Connection and disconnection of the clutch -114 is accomplished by establishing a pressure differential on opposite sides of radial extension 110 in accordance with my U.S. ~. -Patent No. 3,831,463. Another cone clutch 116 can be operated in a similar way for connecting the turbine shaft 24 to the rotatable casing 6/12A. If the turbine shaft is connected to the casing and if the ring of turbine blades 112 is connected to the turbine shaft, the whole blade system will rotate. However, due to the construction and form of the blade system according to the inven~
tion, the ring of guide blades 16 wi].l not rotate at the same :
speed or even practically the same speed as the pump blades or the turbine blades because, even at much lower speeds, it will not significantly agitate circulation of fluid through the blade sys-tem and therefore it will rotate at a considerably lower speed.
Rotation of the ring of guide blades at such speeds . , .

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reduces tlle wear on the free wllcei and/or rela-tively speakillg allows the free ~heel to operate under a higller conllection force on the blocks in the free wheel which is highly - desirable olYlng to the ~idc varia-tion in oil viscosi-ty and without causing wear. Thus the blade system of the in-vention has given the designer a wider scope for better design ancl at the same time reduced wear of the free ~heel.
Fi~ures 5 and ~A show ~lle per~ormance obtained for ., .
a high torque absorption transmission according to l~igure

4 having a blade system according to the invention and with the ring of guide blades mounted on a one-way free whec].
Wh~lco~par~d l~ith ~igure 2, Figure ~ indicates an e~tension o~ the hydraulic torque converter Lield, lYhcre the torq~le converter operates as a coupling. This coupling action, however, due to rapidly falling torque absorption, is not very useful and, for the majority of applications, a lock-up clutch is required. In such circumstances the free wheel avoids, when compared with normal blade systems, the torque absorption of the blade system ~ se at sl)eed j ratio 1 : 1.
When compared with known torque converter transmissions - thi~ particular embodiment havillg a ~ree wheel has the advantage tha-t the differential speed l~ill be low because the guide blades ~ill have a high slip relative to the pump and the turbine blades when the converter is in direct drive.
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4~54;~9 Fi~ures G and 6A sho~Y performance graphs similar to Figures 5 and 5~ but for a torque converter having low torque absorption. It will be observed that different torque absorptions do not essentially change the type of performance and, as described, the virtue of the blade , system according to the invention used in conjunction with arrangements giving the performances indicated in . ,.
Figurcs 5/5A and 6/6A is that5~in direct drive~ the ring ; of guide blades rotates at an essentially lower speed than would be the case in a locked-up torque converter, thereby reducing wear on the free l~heel and allowing - higher spring action for connection of the free wheel.
Figure 7 shows a torque converter which is the same ~31 as that;~f ~igure ~ except that the Lree wheel is omittcd, When this torque converter is in direct drive then the speed ratio is always 1 : 1 and the loss received by having the guide vane stationary, even when the t-urbine is rotating with the turbine shaft, is very low. As mentioned previously, this saves the use of the free wheel in large units and for small units it omits a troubleso~e mechanical part. It also affords new featw es -if~ for instance, the unit is moun-ted in a lift truck ;- because you can have a top speed of the truck when hydraulic drive is used. Thus a speed range is available which is c~;f,o~5 suitable for normal working~and, when direct drive is `~ connected, a higher top speed is available for transporting , . . .
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One advantage of this embodiment is that it is now possible without incurring excessive losses to produce a torque converter whicll can operate in direct drive with~
stationary ring of guide blades Figure 8 shows the torque absorption o~ -the torquc converters accordin~ to ~igures ~ and 7 at and helow the direct drivc condition, These graphs show that for most applications, especially for large vehicles, omission of the free wheel for the guide blades is justified whereas for smaller vehicles with high speed engines, ~ostly running in direct drive, the free wheel may be included.
Point 2 and the line 2 show dcvelop~ent of the torque absorption at and below n2/nl = 1.0 for -the torque converter of the invention having a stationary guide vane. ~his means at n2/nl = 1.0, the direct drive may be connected without free wheel.
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Point 1 shows the torque ab~orption at and below n2/n = 1 .o for known torque converters having a known blade system with the ring of guide blades mounted on a free ,, . ~
~ wheel.

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when a torque conYer-ter with the bladc system accor~ing to the invention has a free ~heel. ~
The difference between points 1 and 3 depends on whetller or not the ring of guide blades is allo~ed a considerable drag relative to the pump and the turbine blades without increasing the torque absorption. This diagram indicates why, in some cases, the torque ,~
; characteristic of the blade system of the invention renders a rree wheel;unnecessary, even in direct drive and why, in other case~s wllen using a free t~heel and direct dr:ive3 both thQ running conditlons or the free wheel are improved , .
and the losses in direct drive ale diminished in relation to known forms of torque converters. To obtain a good understanding of the influence on fuel consumption it is necessary to divide the percentage losses at maximum power the percentage average load of the engine for the application under consideration. This means that for an application with high average load, the extra loss when omitting the free whee] is of minor importance, whereas for an application, using a high speed and having a relatively low average load, the extra loss in question will be of considerable importance. For instance a torque converter for an industrial application can omit the free wlleel if using the blade system of the invention with a locl~~up clutch connected.

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Figure 9 s~ows the cross-sectional shaI)e of the . ~; . . . .
"`3 torque convertcr workillg challlber, in which by application of the blade system of the invention the.perforlllance ~i graphs of Fi.g-ures 2, 2A, 3, 3~, 5,5A, 6,6A and 8 are obtained. The cross-sectional shape of the workillg -chamber, howe~rer, is not essential for achieving the objects of the invention. However, the cross-sectional ~ shape shown combines the features of the invention ~ith `~ . advantageous features for fabrication and it is, there-~ore, of value that the performance is achieved with this particular cross-section. ~:
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. ; ~. r~'igures 10~, lOB and lOC show, schematically pump l~i~ turbine 30 and gui.de blades 16 bearing reIer-ences relating to characteristic dimensions and angular .
. relationships concerning disposition of the blades in . their blade rings. In these Figures, the radii bearing . relerence R2 etc. relate to radii bearing the same refer-~ ences in Figure 9. In -these Figures-- ..
;~ ~ (alpha) indi.ca-tes the inlet ang].e of the several blades and b the minimu~ dlstance between adjacent blades in the same blade ring, Considered slightly ., , .. .
diflerently, b is the narrowest or throat portion of the low channels formed between adjacent blades Considered ~`t' - geometricaliy, c~ is that angle formed bet~een a tangent . . ~ , ~ dra~n to a circle of radius b struck from a centre located ~ i , , , - ,:
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.~ on the inlet edge of the blade, and another tangent ~ ' drawn at the said centre and to a circle containing :
all the inlet edges of a ring o~ blades, for exalllple, , a circle of radius R3 for the pllm]p blades.
, ~ ~beta) is that angle between a chord CH drawn ", and a ra,dial line RE (Figure 10~). -,.~ ~ (gamma) is that angle s-u'btended at the axis of . rotation X of -the blade system by inlet edges Iiand Ii~
. of the ri,ng of turbine blades shown in Figure lOB.
. ~ (delta) is a measure o~ the curva-ture or . angular de.v:Lation between the in'l.et and outlet of each .~ . ' , blade an,d is the angle formed at the :interseotion o~
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centrc lines drawn through the in:Let ancl outlet etlges'of ~' a blad,e.
Z is the number of blades in a particular blade ring.
. ~0 is the pitch oI the in].et edges oI a ring of ~ blades, As an approximation, ~ ~ consicdered as a ,j ~ circum~erential dimension o~ a circle o~ radius R5 (Figure lOB) is equal to the chorcl Ii ~ Iii and Sin c~ (Calculated) = b ' ~nd o< = ~ (calcula-ted) ~ ~
2 ~' , . ',~ .
~ Figures llA and llB show a preferred cross sec-tional '' .~ . ' shape ~or the turbille and guide blades respectivel~ cach ~l blade having a curved inlet of radius represented by ., ~ ' .

' ' ." ' . .: . . .: .
.. . . . .. . . .. . .

:- , ' ' "' ' ' : .
' ~ ' ' ' ' ~ : .

` 1~4~5q~
re~erence r and a tapered or bevellecl outlet edge.
In these Figures the maximum length and width of the blades are indicated as a and c respectively, Figure 12 shows a pump blade in cross-section having a length a and a breadth c and inlet and outlet edges of radius r. Although reference r has been used for nose radii.in Figures llA, llB and 12, the actual dimension of the radius for the respective blades i5 no-t necessarily the same, Further Figures llA, llB and 12 ~ust be viewed in conjunction ~rith Figures lOA, lOB and lOC showing the angular relationship of the b:lades. Usc of the pump blade of ~igure 12 affords the torque abs.orption Ms oharacteristic o~ Figures 2,3,5 and 6 in Yhlch the continuolls line~ ~ e/~
represents the highest Ms and the dotted line represents the lo~Yest Ms, Where yet higher and lower Ms values are required, certain changes to the inlet and outlet portions of the pump blade should be made. Such changas would not, however, change the advantageous characteristics o~ a blade system according to t,he invention.
The following table shows the ranges of ang:les 0~, and ~ and a ratio Ro/Ri (namely the ratio of the radii of -the outlet and inlet edges)~r~ the pump, turbine and guide blades of the blade system hereindescribed, '~ , ' . ' , ' :

' ;~ ~ ' ' ' '~-1 . . . ,:
Y
~ .,. ' ' :. ,, .' " , ' . , ' ` `' ' ', ' ' .~,- ,,, '' 104~5Cg . T A 1~ L E

. ' Rat l o ~ ~ ~. .. . _ _ . . R o/R i o~ ~ ~) , . . . _ . __ _ . . _ _ . .
. Blade max min max min max min max min max lUi 11 . . ____ - .... _ .... _____ . - __ _ Guide .1,27 1.10 o ~ o 42 25 15 5 ~0 110 .~ _ . .. . _ . _ .. .~
. Pump 1,70 1.4~ 110 70 25 10 20 12 ~10 -30~
.
Turbine 0.6 0. 5 35 1~ 22 8 18~ lU~ t,0~ lU~

.' . . . . . . .
. . ,~. ' " ' ,.
' . . ..
. ..
. . , ' ' ' ' ,,"
. .
.
. ' ~ .
. . ' ,. ..
, . ?, .
. , , ' . ''' ,.i ' , ....
~' ' .
..
: , ... .. .
i .

, ~ , ' - ; - ~ ,

Claims (14)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED
AS FOLLOWS:

1. A hydrodynamic torque converter comprising a rotatable casing enclosing a closed circuit for circulation of a work-ing fluid defined by a torroidal working chamber having an annular core therein, the closed circuit including in cross-section an outflow section, an inflow section and radial inner and radial outer transition regions connecting the inflow and outflow sections, a blade system located within the working chamber and including a ring of pump blades, a ring of guide blades, and a ring of turbine blades, the blades of the blade system being generally radially dis-posed within the working chamber in accordance with the parameters set out in the following table, in which Ro/Ri is the ratio of the outlet and inlet radii for the res-pective rings of blades, .alpha. (alpha) is the inlet angle of the blades,.beta. (beta) is that angle formed between a chord drawn for a blade and a radial line drawn from the centre of rotation of the system and the outermost edge of the blade, ? (gamma) is the angle subtended at the centre of rotation of the blade system by the innermost edges of two adjacent blades, ? (delta) is a measure of the curvature of the blade, and in which the radii of the outermost edges of the pump (R3) and turbine (R4) blades are at least 85%
of the maximum, radius of the torroidal working chamber.

T A B L E

2. A torque converter according to Claim 1 wherein the ring of pump blades is fixedly mounted against rotation in either direction and including a lock-up clutch.

3. A torque converter according to Claim 1 wherein the ring of guide blades is rotationally fixed relative to a stationary abutment.

4. A torque converter according to Claim 1 wherein the ring of guide blades is mounted on a free wheel carried by a stationary abutment.

5. A torque converter according to Claim 1 wherein the ring of turbine blades is rotationally fixedly carried by a turbine shaft constituting an output for the converter.

6. A torque converter according to Claim 4 wherein the -free wheel includes a spring member having a connecting spring force providing a slip torque between 0.5 and 1% of torque converter, torque absorption at maximum efficiency point so as to reduce the slip speed.

7. A torque converter according to Claim 1 in which the blades of the said turbine ring have an inlet radius of about .3% of the length of the blade and the blades of the said guide ring have a nose radius about 13% of the length of the blade.

8. A torque converter according to Claim 1 having a blade system, wherein the value of .beta. (beta) for the pump, turbine and guide blades fall within the ranges of 20°, 16°, 22°, 12°
39° 29° respectively.

9. A torque converter according to Claim 1 wherein the value of .alpha. for the pump, turbine and guide blades fall within the ranges 86°, 83°, 25°, 14°, 31°, 24° respectively.

10. A torque converter according to Claim 1 wherein the radial positions of outlet of the pump, inlet of the turbine and outlet of the blades fall within the ranges 85%
85-96%, 50-65% considered as percentages of the maximum diameter of the torroidal working chamber.

11. A torque converter according to Claim 1 wherein the value of (delta) for the pump, turbine and guide blades fall within the ranges +10-°-30°, 80°-100°, 40°-80°, respectively.

12. A torque converter according to Claim 1 wherein the torroidal working chamber has axial extension less than 50%
of the maximum diameter thereof.

13. A torque converter according to Claim 1 including a lock-up clutch and means for selectively releasing the ring of turbine blades from an extension of a secondary output shaft.

14. A torque converter according to Claim 1 in which the Ro/Ri ratio for the pump, the turbine and the guide blades fall within the ranges 1.7 - 1.45; 0.6 - 0.5; 1.2-1.1, respectively.