EP0257028A1 - Infinitely variable speed gear drive - Google Patents

Abstract

An infinitely variable speed gear drive comprises shafts or parts (100, 101, 102, 124) driving or driven, and at least one flexible transmission element which acts between said parts and rotates them during operation. This element has the form of a finished open loop with variable dimensions in order to allow, when necessary, a variation of the transmission ratio between said parts. The flexible transmission elements are chains (104, 104 ') or the like which cooperate with a number of rotating wheels (105, 105', 122, 122 ', 123, 123') or sliding elements, being supported by these. Some wheels (105, 105 ') are connected to one of the shafts or parts (100, 101, 102, 124) so as to drive them, and are provided with teeth. At least one of the toothed wheels (105, 105 ') always mechanically engages a chain. At least some wheels (105, 105 ', 122, 122', 123, 123 ') or sliding elements can move inwards and outwards using an adjustment mechanism (106), in order to to modify the length of the loop and consequently the transmission ratio between said shafts or parts.

Description

INFINITELY VARIABLE SPEED GEAR DRIVE Technical field of the invention

This invention relates to an infinitely variable speed gear drive including driving and driven shafts or parts and at least one transmission element, e.g. in the form of a chain or toothed belt, acting between said parts and being arranged in an open loop with a variable size, one end of which being fixedly attached and the other end being resiliently attached, said element being provided with a plurality of seats intended for the engagement with teeth or cogs, a plurality of rotatable wheels or glide elements being associated with and carrying each transmission element, at least one of said wheels being provided with teeth or cogs for engaging the transmission element and being drivingly connected to one of said shafts or parts, the wheels or glide elements being associated to a respective transmission element being situated in the same plane as the transmission element and at least some of the wheels or glide elements being movable inwards or outwards by means of an adjustment mechanism by which means the transmission ratio between the shafts or parts can be varied.

An infinitely variable speed gear drive or torque converter of this kind can be used in many technical fields, for instance for regulating the rotational speed of machine tools, regulating the speed of conveyers, for wind powered or other power stations, for the power transmission in mobile units or other applications where it for instance is desired to vary the outgoing rotational speed of an electric motor with a constant rotational speed.

State of the art

In the so called variator drives that in practice witherto have been used the torque is in most cases transmitted from the driving to the driven part by means of friction between driving belts and conically surfaces being sidewardly movable. This means that the coefficient of utilisation will be relatively small and that the power that can be transmitted will be severely curtailed. Similar effects will arise in hydrodynamic and hydrostatic transmissions devices due to the friction of the hydraulic fluid. There further exist so called bicycle gears including an endless chain laid in a. loop around segments or not rotatable chain wheels arranged on arms and that can move inwards respectively outwards from a common centre whilst diminishing the size of the chain loop. In these kinds of gears the transmittable torque is relatively small in addition to which the rotational speed will vary during each turn due to the so-called polygon-effect.

Gears of the introductorily mentioned kind are in the patent documentation disclosed by DE-B-1067797 and AT-C-179160. These known gears suffer however from a number of drawbacks. The transmission element is here stationary arranged and the chain wheels, that are included in the gear,roll on the transmission element. This means that the chain wheels will rotate around a common centre together with the adjustment mechanism that controls the movement of the wheels to and from this common centre. As a consequence of this it will be complicated and expensive to create an adjustment mechanism that is adjustable during operation. An example of an attempt to devise a mechanism that is adjustable during operation is shown ia AT-C-179160. The chain wheels are here mounted on screw mechanisms being influenced by a cog gear that normally rotates with the entire device. Drum brakes are associated to the cog gear that brake the cog gear when activated which leads to that the screw mechanism starts to rotate. It is difficult to adjust this mechanism exactly since it is difficult to decide how long braking, time is needed in order to move the chain wheels a certain distance, especially since the rotation of the screw mechanism is stored in a spring mechanism until the chain wheel is unloaded when it is disengaged from the transmission element and the screw mechanism can start to rotate. The use of this particular adjustment mechanism leads also to that the possibilities to drive the chain wheels largely is limited to the endless chain as shown which has the customary drawbacks that are associated to a chain drive.

In DE-B-1037797 an adjustment mechanism is shown that is included in the planetary gearing that is used to drive the chain wheels that roll on the transmission element. It is not at all clear in this patent specification how this adjustment mechanism can be actuated during operation.

A device having some superficial similarities with the above mentioned devices is disclosed in DE-C-633642. This device also includes a transmission element in the form of a finite loop co-operating with a number of wheels. The transmission element does however not seem to be provided with seats for the engagement with teeth or cogs and cannot be considered to form an open loop. The transmission element is intended to be able to drive only one wheel which means that, when the wheel passes the opening in the loop, it must engage one part of the loop before it disengages from the second part. Should the wheel be provided with teeth intended to engage seats in the transmission element, the wheel will be entirely locked when it is in engagement with the second part and can only engage the first part when the pitch, i.e. the distance between the seats, on both sides of the opening co-incide exactly, which not normally is the case in a infinitely variable loop. Since both parts are fixed on a common lock, smaller differences in the pitch cannot be compensated by a limited flexing of the transmission element. The power transmission between the transmission element and the wheels does thus only seem to be possible by means of friction and and the device thus is not of the same kind as the above mentioned devices and does not form a part of the state of the art for the relevanttype of infinitely variable speed gear drives.

Brief description of the inventive concept

The present invention aims to remove the drawbacks of the previously known gears of the introductorily mentioned kind and to unite the infinite variability of variators with the high co-efficient of utilisation of chain- and cog gears. These and other aims of the invention are ,in accordance with the most characterizing of the invention, obtained by the means that the open loop formed by the transmission elements in operation rotates relative to the wheels, that each tooth- or cog-provided wheel entirely is disengaged from one part of the transmission element before engaging the other part when the opening in the loop passes the wheel and that the transmission elements and wheels are arranged in a way that always at least one tooth- or cog-provided wheel is in engagement with at least one transmission element.

In accordance with a preferred embodiment of the invention the transmission element is attached to one of the driving respectively driven parts at two opposite ends, at least one of which being connected to a spring, the end part of said element being connected to the spring being laid over a pulley wheel by which means the part of the said el'ement extending between this pulley wheel and the spring automatically is lengthened respectively shortened by means of the spring in dependence on whether the cog or tooth wheels move inwards respectively outwards from the centre.

Brief description of the attached drawings

In the drawings Fig. 1 is a perspective view that in an extremely simplified and schematic way illustrates the fundamental principle of one embodiment of the invention, Fig. 2 is a side view of a part of a further developed embodiment of a prototype of the invention (see also section II-II in Fig. 3), Fig. 3 is a section III-III in Fig. 2, Fig. 4 a section similar to the one according to Fig. 3, although in reduced scale and showing other parts included in the gear (see also section IV-IV in Fig. 5), Fig. 5 is a section V-V in Fig. 4, Fig. 6 a further such section showing further other parts included in the gear (see also section VI-VI in Fig. 7), Fig. 7 is a section VII-VII in Fig. 6, Fig. 8 is an analogous section illustrating a planetary gearing and a reverse gear mechanism advantageously included in the gear according to the invention, Fig. 9 a section IX-IX in Fig. 8 showing the reversing gear mechanism in question, Fig. 10 a similar section although showing the reversing gear mechanism in an alternative functional position, Fig. 11 is a section XI-XI in Fig. 8 and showing the planetary gearing, and Fig. 12 shows schematically the fundamental principle of a second embodiment of the invention.

It should be pointed out that the sections in Fig. 3, Fig. 4 and the left part of Fig. 6 are sectioned in one and the same part of the prototype in question although showing different components included in the construction. This manner of illustration has been chosen in order to obtain the greatest possible clarity, since there are difficulties to include all components in one and the same drawing. The above mentioned sections thus can be imagined to be superimposed.

Detailed description of the fundamental inventive concept

In Fig. 1 1 denotes the input or driving shaft or part that transmits a torque moment to a driven or output part 2, which can be varied by means of the gear located between said parts , in its entirety denoted with 3. This gear includes as main components on one hand a transmission element 4,in this case in the form of a chain, and on the other hand a number of rotatable cog- or tooth-provided wheels 5,5' ,5" being drivingly connected to the driving shafts, at least one of which always being in mechanical engagement with the chain 4.

In the example shown the number of cog wheels 5 are three. These cog wheels 5 are situated in the same plane as the chain 4 and are movable to and from a common centre by means of an adjustment mechanism ,in its entirety de- noted with 6.

The above-mentioned cog wheels 5 are arranged on first rotatable shafts 7,7',7" having first gears or similar 8, 8 ',8", each of which being in engagement with second gears 9, 9 ',9" on second shafts 10, 10',10", being rotatable ,but stationary in space, and forcibly arranged to rotate with the same rotational speed. In the example shown,this has been realized by the means that the shafts 10 have third gears 11,11',11" being in engagement with a common gear 12 which in turn is torsionalIy rigidly connected to the input shaft 1. In this context it should be pointed out that it does not matter if the shaft 1 is connected to the main gear 12 or to one of the three surrounding gears 11,11',11". It is only essential that the shafts 10, when rotated, are given the same rotational speed independently of where the power is applied.

In the example shown the adjustment mechanism 6 is in the form of a linkage system that, upon movement of one of the first shafts 7,7',7" a distance along the peripheri of the associated second gear 9, forcibly moves the other first shafts an equal distance, in this way ensuring that all first gears and thereby all adjustable cog wheels always are at the same distance from their common centre irrespective of the absolute length of this distance. The linkage system 6 includes a carrier disc 13,13',13" for each cog wheel 5 being swingable around a centre coinciding with the associated second shaft. Each such carrier disc has the purpose to, at an adjustment operation, move the associated first shaft 7,7',7" in a circular path around the second shaft 10,10',10". All carrier discs present are interconnected by means of articulated links 14,14',14" that, when one disc is swung around a second shaft, forcibly swing the other discs in a similar way. In the example shown, the disc 13 is shaped with an extension 15 in the form of a handle by means of which the disc can be manually adjusted between different adjustment positions.

The chain 4 is attached to the driven part 2 at two opposite ends 16, 17,one of which, 16, being connected to a spring 18, which in the example is illustrated by a helical tension spring whose one end is attached to the periphery of the circular disc-formed part 4 whilst its opposite end is attached to a bar 19 extending between two swingable arms and at whose free end the chain 5 is attached. The end part of the chain 5 that is connected to the spring 18 is laid over a pulley wheel 20 that preferably, but not necessarily, is provided with teeth. Thanks to the spring 18 the part 21 of the chain that extends between the pulley wheel and the end 16 will automatically be lengthened respectively shortened in dependence on whether the cog wheels move inwards to, respectively outwards from, the centre.

In Fig. 12 101 denotes an input or driving shaft and 102 an output or driven shaft. The gear is arranged between these and consists in this embodiment of two transmission elements 104,104' in the form of chains. To each chain is associated a tooth- or cog- provided wheel 105,105'. These two cog wheels are mounted on a common shaft 107 that,by means of a gear mechanism 108, 109, is drivingly connected to the input shaft by means of the gear 108 arranged on the shaft 107 and the gear 109 arranged on the input shaft 101, 110. In addition to the cog wheels 105, 105',two freely rotatable pulley or supporting wheels 122,122',123,123' are associated to each chain that, together with the cog wheels 105,105', stretches the open loop formed by the chain. Both sets of wheels are located on an adjustment mechanism 106 by the means of which the wheels can be moved from and to a common centre. The adjustment mechanism is in the form of a linkage system that, by movement of the gear 108 and the shaft 107 along the periphery of the gear 109, forcibly moves the supporting wheels an equal distance.

The linkage system 106 includes a carrier arm 113 intended for the cog wheels 105,105' and which is swingable around the centre of the input shaft 101. The purpose of the carrier arm 113 is to, at an adjustment, move the associated shaft 107 in a circular path around the input shaft 101. The carrier arm 113 is by means of articulated links 114,114',114" articulatedly connected to swingable carrier arms 113',113" whereon shafts are arranged, each carrying pulley or supporting wheels 122,122',123, 123'. When one carrier is swung, the other carrier arms will forcibly be swung in a similar way. In the example shown, the carrier arm 113 is designed with an extension in the form of a handle 115 by the means of which the adjusting mechanism can be adjusted manually between different adjustment positions. The chains 104 and 104' are each attached in two opposite ends 116,116' and

117,117', of which one, 116,116', is connected to a spring 118,118, which in this example is illustrated by a helical tension spring whose one end is attached to the periphery of the circular disc-formed part 120 whilst the opposite end is attached to a bar arranged in a swingable arm and at whose free end the chain 105,105' is attached. The end part of the chain 105,105' being connected to the spring 118,118' is laid over a pulley wheel 120,120'. Thanks to the spring 118,118' the part of the chain 121,121' that extends between the pulley wheel and the end 116,116' will automatically be lengthened or shortened in dependence on whether the cog wheels 105, 105' with the associated pulley wheels moves inwards to respectively outwards from the centre. To ensure that one cog wheel always engages one chain the two chain loops are displaced in relation to each other, in this embodiment preferably at 180°.

The function of the invention

The device according to Fig.1 functions in principle thus that a torque being applied onto the input shaft 1 is transmitted to the stationarily arranged shafts 10,10',10" by means of the gears 12 and 11 in such a way, that these are brought to rotate in a certain transmission ratio decided by the mechanism 6 in that, by means of the gears 9,8, the rotation of the shaft 10 is transmitted to the shafts 7 and the thereon arranged cog- or toothed wheels 5 who in turn pull the chain 4 so that this, by means of the transmission bar 19', brings the part 2 to rotate. If now the handle 15 is swung in a counter-clockwise direction in accordance with Fig 1, the shafts 7,7',7" and the associated gears 8,8',8" will describe part-circular paths around the shaft 10,

10' whilst keeping the engagement between the gears 8-9, 8'-9' and 8 "-9". By this fact follows that also the cog wheels 5, 5',5" will describe a circular path, more specifically in a direction inwards towards their common centre. During this inwards movement the cog wheels 5 will keep their peripheral speed, which means that the chain 4 will drive the part 2 with a rotational speed that is higher than the original one on condition that one and the same load is maintained. In other words, the transmission ratio is reduced between the input and output parts 1 and 2 respectively in proportion to the decreasing distances between the cog wheels 5,5',5". Inversely the transmission ratio will increase when the cog wheels are distanced from each other by swinging the handle 15 in a clockwise direction.

The device according to Fig. 12 functions on the whole in the same way as the device according to Fig 1.

A torque that is applied onto the input shaft 101 is transmitted to the shaft 107 by means of the gears 109 and 108. For a given position of the adjustment mechanism 106 this is transmitted to the driven part 100 in a certain ratio decided by the mechanism 106 in that the the cog wheels 105,105' arranged on the shaft 107 will pull the chains 104, 104' so that these bring the part 100 to rotate by means of the transmission bars 119, 119'. If now the handle 115 is swung in a clockwise direction according to Fig. 12, the shaft 107 with its associated gear 108 will describe a partcircular path around the input shaft 101 whilst keeping the engagement between the gears 108 and 109. From this follows that the cog wheels 105,105' also will describe a circular path, more specifically in an outward direction. By means of the linkage system included in the adjustment mechanism 106 the pulley and supporting wheels 122,122',123,123' will also move outwards in a circular path by which means the length of the loop will increase. Since the peripheral speed of the cog wheels will not change ,the chains 104,104' will drive the part 100 with a rotational speed that is lower than the original one on condition that one and the same load is maintained.

In the embodiments shown in Figs. 1 and 12, the adjustment mechanism 6, 106 is conceived to be manually controllable. The mechanism in question can of course also be modified to work automatically. The handle 15,115 can for instance be conceived to be connected with a spring attached to a fixed point and which always strives to move the handle to one of two opposite end positions and against the action of which the handle and thus also the cog wheels 5,5',5" and 105,105' respectively are movable in dependence of a varying load on the driven or output part 2 and 102 respectively. In this context it should also be emphasized that the part 2,102 also can serve as an input or driving part at the same time that the shaft 1,101 becomes an output or driven part. It should also be pointed out that the described examples only have been given as illustrating examples that can be varied in various respects. In the example shown in Fig. 1 actually not more than two driving cog wheels per chain is needed to ensure that at least one cog wheel is in engagement with the chain. Other elements, that are necessary to stretch the loop formed by the chain, could be glide elements or freely rotatable pulley or supporting wheels. In the example according to Fig. 12 the gear only needs one driving cog wheel per chain and the remaining wheels have been designed as freely rotatable pulley or supporting wheels. In certain more simple fields of use, where the requirements on the size of the transmission ratio and on the size of the transmitted torque are not great, the pulley and supporting wheels can possibly be designed to be stationary and only the driving wheels be designed movable which means that the adjustment mechanism can be very simply designed. Furthermore , other systems for the adjustment of the wheels can be used instead of just a linkage system. The adjustment mechanism can for instance be designed as a central disc surrounded by a rotatable ring being concentrical with and located outside the disc and having link arms being articulatedly attached to both ring and disc and carrying the shafts 7,107 at their ends. If the ring is displaced relative to the disc, the ends of the link arms extending past the articulating points will describe a circular path in the same way as in the earlier described linkage mechanisms. Another conceiveable adjustment mechanism is illustrated below under the designation 38. It is also conceiveable to use other transmissions than gears for the rotation of the shafts 10,110 to the shaft 7,107. In the example illustrated in Fig. 12, a particularly simple solution of the power transmission to the shaft 107 can be arranged in that for instance an electrical, pneumatic or hydraulic motor 124 can be arranged directly on the end of the shaft 107 by which means the motor is moved together with the shaft 107 by the adjustment mechanism 106. It is further conceivable that the shaft 107 is connected directly to the stationary driven or driving shaft 101 and only the pulley or supporting wheels 122, 122',123,123' are arranged to be movable. Other variations are also conceiveable within the scope of the appended claims.

In this context it should be pointed out that the tooth- or cog-provided wheels 5,5',5",105,105', advantagously can be provided with free wheeling hubs, that on one hand ensure a torsionally rigid connection between the shafts 7,107 and the teeth- or cog-provided wheels during the rotation in a driving direction, and on the other hand allows the wheels to idle at the application of a force on the wheels in the opposite direction. By these means it is ensured that the transmission element does not jump off the wheels if the output shaft is made to rotate faster than corresponding to the transmission ratio as adjusted and the rotational speed of the input shaft. It is further ensured that the cogs or teeth of the wheel can remain in a correct engagement with the transmission element independent of varying adjustment distances between adjacent cog wheels. The engagement of the cogs or teeth of the wheels in one part of the transmission element when the wheels pass the opening in the loop formed by the element in question is also facilitated.

Detailed description of the embodiment according to Figs. 2 - 11

The embodiments according to Figs. 2-5 are on the whole a further developed embodiment of the device according to Fig. 1 and are on the whole described in relation thereto. The adjustment mechanism 38 shown in Fig. 3 is of course also applicable to the device according to Fig. 12, the carrier device then for instance being imagined to be swingable around an imagined axis coinciding with the shaft 110 or, if it is used in a device according to Fig. l,around an imagined axis co-inciding for instance with one of the shafts 10 instead of being swingable around an imagined axis co-inciding with the shaft 28.

The embodiment according to Fig. 6-7 illustrates an advantageous embodiment where the gear co-operates with an automatic adjustment mechanism or rotational speed controlling device. It has on the whole been described in connection with the device according to Figs. 2-5 but can of course also be used in the embodiments according to Fig. 1 and 12, for instance by connecting the controlling device directly to the handle 15,115 by means of an suitable transmission mechanism like for instance the rack 54 or that, alternatively, the adjustment mechanism 38 is used.

Figs. 8-11 illustrate an advantageous embodiment where the gear on one hand co-operates with the planetary gearing and on the other hand with a reversing gear mechanism co-operating with the planetary gearing.

Reference is now made to Figs. 2 and 3 in combination with the sections shown in the reduced scale in Figs. 4-7. In order to, by way of introduction, give an orientation in the drawings it should be pointed out that the embodiment of the gear that is shown in Fig. 2-7 and that is in the form of an further developed prototype, is built into a housing including a bottom 22 a roof 23 and four mutually separated partitions 24,25,26 and 27.

It is characteristic for the embodiment shown that it includes two transmission chains instead of one, as shown in Fig. 1, in order to increase the possible ratio of transmission.

In Figs. 3 and 4 28 denotes an input shaft whilst 29 denotes an output shaft. A rotatable ring 30 (Figs. 2 and 3) can be driven by means of two transmission chains 31,31' placed on each side of a central plane through the ring. In Fig. 4 it can be seen how the input shaft 28 is stationary although rotatably journalled in the walls 24,25 and has a gear 32 (corresponding to one of the gears 11 in Fig. 1) that by means of a main gear 33 (12 in Fig. 1) is connected to two further gears being in an analogous way mounted on shafts; 28' being journalled in the walls 24,25. On the inner ends of the shaft 28 gears 34 are torsionally rigidly mounted (corresponding to the gears 9 in Fig. 1). On the opposite side of the ring 30 there is an analogous set of gears 34 A being mounted on shafts 28 A that are journalled in the partition 26 and carry gears 32 A that all are in engagement with a common main gear 33 A.

A gear 35 (8 in Fig. 1) is in engagement with each such gear 34 and is journalled on a shaft 36 that at its one end is connected to the free end of an arm 37 being swingably journalled. around the shaft 28, said shaft 36 being at its opposite end connected to a carrier device generally denoted with 38 (see detail 13 in Fig. 1) in this case being composed by two separated, mutually parallel discs 39,39'. The gear 35 is torsionally rigidly connected to a cog wheel 40(5 in Fig 1) being in mechanical engagement with the chain 31 in question. More specifically, the gear 35 is connected to the cog wheel 40 by means of a free wheeling hub as described above.

With reference to Fig. 3 it should be noted that the carrier device 38 formed by the discs 39,39' is swingably movable around an imagined axis coinciding with the shaft 28. This has however not been realized by means of a concrete shaft. Instead of this,the device 38 is,similar to the middle part of a crankshaft carried by on one hand the shaft 36 and on the other hand by an analogous shaft 36 A at the opposite end, this last-mentioned shafts 36 in turn being carried by an arm 37 A which in similarity with the arm 37 is journalled around the shaft 28 A (see also Fig. 4).

In order to effect the swinging of the carrying device 38 between different adjustment positions of the cog wheels 40, it is provided with a pin 42 being in engagement with a groove 43 (see Fig. 7) in an adjustment wheel 44 being included in an automatically working adjustment mechanism that will be described below. This wheel 44 is localized between the disc 39 and 39' and does not rotate with the ring 30, which incidentally also is the case with the carrier device 38 and the cog wheels 40, the gears 35 and the arms 37. Those last mentioned components thus normally are stationary and only move with a limited angular movement in connection with an adjustment of the transmission ratio.

It should be clear from the above description in combination with Fig. 2 that the arrangement includes three carrier devices 38, 38',38" that each in turn includes two gears 35,35 A located on opposite sides on the central plane of the ring together with thereto associated cog wheels 40,40 A and arms 37,37 A.

The chains 31,31', are as described above, arranged in loops around the cog wheels 40 situated in the same plane and connected to springs 45,45' (18 in Fig. 1) being attached to a common bar 46. In similarity with the embodiment shown in Fig. 1 the chains 31,31' are also laid around pulley wheels 47,47' (20 in Fig. 1).

Reference is now particularly made to Figs. 6 and 7 that illustrate an automatic adjustment mechanism or rotational speed controlling device preferred together with the gear. This controlling device includes a hub part

48 being rotatable by means of one of the shafts 28 A and from which a rotationally symmetrical body projects having a linear or curve-shaped inner contour, or cam guiding device, 49 co-operating with at least two weights, for instance balls 50, that are guided by a guide 51 and arranged to influence a disc part 52 being axially displaceable along the hub part 48 and which by means of a spring 53 normally is kept in a initial position as close to the bottom of the curve-shaped guide 49 as possible. At its free end the disc part 52 is rotatably journalled relative to a rack 54, although immovably connected thereto. The rack 54 is by means of an intermediate gear 55 in engagement with a main gear 56 that in turn by means of a bevel gear drive 57 can effect a rotation of a through-going shaft 58 whereon the adjustment wheel 44 is torsionally rigidly attached. This shaft 58 can possibly also be manually rotatable by means of a crank 59 or similar.

At a comparatively high rotational speed of the hub part 48, due to a comparatively low load on the outgoing or driven shaft of the gear, the weight or balls 50 are pressed outwards towards the peripheral part of the cam guides 49 in question. By these means the disc part 52 is pressed towards the right in Fig. 6 as shown with dash and dot lines, the rack 54 keeping the adjustment wheel in a position wherein the cog-wheels 40 are in positions corresponding to the actual rotational speed, by means of the gears 55,56, the bevel gear drive 57 and the shaft 58. If after this the rotational speed is reduced due to an increasing load on the output shaft in the system,the spring 53 overcomes the centrifugal force exerted by the balls 50, whereby the disc part 52 is allowed to move in direction towards the position shown with continuous lines in Fig. 6. This in turn leads to that the adjustment wheel 44 is rotated a distance corresponding to the actual reduction in rotational speed by which means the carrier devices 38 adjust the cog wheels 40 in the above, in connection with Fig. 1, described way so that the transmission ratio between the input shaft and the output shaft in the system increases, thus compensating the increasing load on the output shaft.

If the automatic rotational speed controlling device is used together with the embodiments according to Fig 1 or 12, the hub-part 48 could for instance be rotated by means of a shaft driven by the output shaft 1,102.

Reference is now made to Figs. 8-11 that illustrate on one hand a planetary gearing co-operating with the gear and on the other hand a reversing gear mechanism cooperating with this planetary gearing. In Fig 8 60 denotes a shaft that in practice is imagined to work with a constant rotational speed, something which can be realized by the means that the shaft by means of gears is connected to the same motor or power source that drives the above described gear. 61 denotes a shaft that works with a rotational speed varying in dependence on the adjustment position of the described gear. The shaft 61 thus is imagined to be connected to the outgoing or driven part of the gear. The shafts 60,61 are interconnected by gears 62,63 of which the last mentioned by means of pins 64 are in engagement with the planetary wheels 65, 65', 65" of an per se known planetary gearing arrangement that additionally includes a sun wheel 66 and a ring wheel 67 provided with an external as well as an internal gear. The shaft 61 is further, by means of the plnetary gearing in Fig. 11 and the reversing gear mechanism in Figs. 9,10, also connected to an output shaft 68 whereon a gear 69 is torsionally rigidly mounted which together with the wheel 67 forms the two main gears of the reversing gear mechanism in question. As best can be seen in Fig. 9 these main wheels 69,67 are separated from each other but arranged to co-operate mutually by means of a pair also cog-provided intermediate wheels 70,71 of which one, 71, is rotatably mounted on a first arm in a form of a handle 72 being swingable relative to the shaft

60. The other intermediate gear 70 is rotatably mounted on a second shaft 73 being swingable relative to the shaft 68 and connected to the first arm 72 by means of an articulated link 74. These two arms 72,73 are swingable between on one hand a first position wherein the intermediate gear 71 simultaneously is in engagement with the two main gears 67,69 as shown in Fig. 9 and by means of said first intermediate gear 71 being brought to rotate in one and the same rotational direction, and,on the other hand, a second position wherein the intermediate gears 70 and 71 as shown in Fig. 10 are in a mutual engagement as well as each being engagement with the main gears. Hereby the main gears 60,69 are made to rotate in opposite rotational directions by means of the two intermediate gears. Shifting of the two intermediate gears between forwards and reverse . is in practice done by means of the arm 72 serving as a handle.

Thanks to the described planetary gear arrangement, the output shaft 68 leading to the consumer can start from zero in both rotational directions, i.e. be in a stationary position in spite of the two shafts 60,61 being driven, by the fact that the planetary wheels 65, 65', 65" roll on the ring wheel 67 without simultaneously pulling this along. If thereafter the rotational speed of the shaft 61 increases, namely by adjustment of the gear described above, and the rotational speed of the shaft 60 at the same time is kept constant, the planetary wheels 65, 65 ',65" will pull the wheels 67 along which by means of the wheel 69 results in a driving of the output shaft 68, irrespective if the reversing gear mechanism is shifted into a forward or a reversing position. The rotation of the output shaft leading to the consumer thus can be continuously varied, from a maximal clockwise rotational speed, to stationary and further on, to maximal counter-clockwise rotational speed.

Advantages of the invention

By means of the gear according to the invention torque can be transmitted in a secure way and with small power losses whilst making possible an infinite variation of the transmission ratio under load. By the particular construction it is obtained that the adjustment mechanism for the gear can be kept simple and light, and be simply influenced by automatic controlling devices which not easily has been possible in the previous art. The embodiment according to Fig 12 in particular has great advantages in this respect as well as when the possibility of varying the location of the input respectively output shafts relatively freely is concerned without any need for complicated power transmissions.

In practice the invention can be applied in a number of technical fields. Thus it can be used for controlling the rotational speed of machine tools and controlling the speed of conveyors, for instance worm conveyors for the feeding of chips or similar into solid fuel furnaces. It can further be used in the connection with wind power or other power stations. Thus the gear can be inserted between on one hand a generator working with a constant rotational speed, and on the other hand, a wind turbine with a variable rotational speed, the operation of the gear being controlled for instance by a tachometer, thyristor and a servo motor for an automatic control of the gear. As has been introductorily mentioned, the gear can also be used for power transmission in mobile units as well as in connection with for instance an electric motor with a constant rotational speed where it is desired to vary the rotational speed of the output shaft.

Possible modifications of the invention

It is evident that the invention is not limited to only the embodiments shown in the drawings and as described. Thus one or several of the shown gear transmissions that are included in the gear can be exchanged against other types of transmissions. The described linkage system can also be modified in different ways and the input respectively the output shafts or parts can of course be varied in a variety of ways in regard of shape as well as of location. It should also be pointed out that the concrete design and location of the described planetary gearing can vary in several ways without leaving the idea of the invention.

In order that the driven or driving cog- or tooth- provided wheels shall have a suitable contactangle with the transmission element the pulley or supporting wheels or glide elements can also be arranged to move in other directions than inwards-outwards at an adjustment of the gear.

A further advantage of the gear according to the invention which is extremely valuable in practice is that it can be constructed by means of cheap standard components for which all data and existing basis of calculations are availabel.

Claims

1. Infinitely variable speed gear drive including driving and driven shafts or parts (1,2,100,101,102,124) and at least one transmission element(4,104,104'), e.g. in the form of a chain or toothed belt, acting between said parts and being arranged in an open loop with a variable size, one end of which being fixedly attached and the other end being resiliently attached, said element being provided with a plurality of seats intended for the engagement with teeth or cogs, a plurality of rotatable wheels or glide elements (5,5',5",105,105',122,122',123, 123') being associated with and carrying each transmission element, at least one of said wheels(5,5',5",105,105') being provided with teeth or cogs for engaging the transmission element and being drivingly connected to one of said shafts or parts (1,2,100,101,102), the wheels or glide elements (5,5',5"), (105,122,123), (105',122',123') being associated to a respective transmission element being situated in the same plane as the transmission element and at least some of the wheels or glide elements being movable inwards or outwards by means of an adjustment mechanism(6,106) by which means the transmission ratio between the shafts or parts (1,2,100, 101,102,124) can be varied, c h a r a c t e r i z e d i n that the open loop formed by the transmission element (4,104,104') in operation rotates relative to the wheels

(5,5',5",105,105',122,122',123,123'),that each tooth-or cog-provided wheel (5,5',5",105,105') is entirely disengaged from one part of the transmission-element before engaging the other part when the opening in the loop passes the wheel and that the transmission elements and wheels are arranged in a way that always at least one tooth-or cog-provided wheel (5,5',5",105,105') is in engagement with at least one transmission element (4,104,104').

2. Gear drive according to claim 1, c h a r a c t e r i z e d i n that at least two tooth- or cog- provided wheels (5,5',5") are associated to the transmission element(4), at least one of which always being in engagement with the transmission element, and that, where appropriate, the remaining elements associated to the transmission element may be glide elements or freely rotatable pulley or supporting wheels.

3. Gear drive according to claim 1, c h a r a ct e r i z e d i n that the number of transmission elements (104, 104') is at least two, that the transmission elements (104, 104') are arranged in a side by side relationship with the openings in the loops formed by the elements(104,104') displaced relative to each other, preferably at 180°, that at least one pair of tooth- or cog-provided wheels(105,105') is arranged on a common shaft(107, each one of said wheels being associated to a transmission element(104,104') each, and that, where appropriate, the remaining elements associated to each transmission element may be glide elements or freely rotatable pulley or supporting wheels (122,122',123,123').

4. Gear drive according to claim 3, c h a r a ct e r i z e d i n that the driving part comprises a motor, preferably electrically, pneumatically or hydraulically actuated, arranged to directly drive the shaft(107) of the cog wheels (105, 105').

5. Gear drive according to any one of the claims 2,3 or 4, c h a r a c t e r i z e d i n that the transmission element(4,104) is attached to one of the driving resp. driven parts (1,2,100,101,102) at two opposite ends( 16,17,116,117), at least one of which being connected to a spring(18,118,118'), the end part of said element being connected to the spring being laid over a pulley wheel ( 20,120,120') by which means the part (21,121,121') of the said element extending between this pulley wheel and the spring(18,118,118') automatically is lengthened respectively shortened by means of the spring in dependence on whether the cog or toothed wheels(5,105) and pulley or supporting wheels move inwards to respectively outwards from the centre.

6. Gear drive according to claims 2 or 3, c h a r a c t e r i z e d i n that the radially adjustable cog wheels (5 ,5',5",105,105') are arranged on first rotatable shafts (7,7',7",107) having first gears(8,8', 8 ",108) each being in engagement with second gears(9,9',9",109) arranged on second shafts (10,10',10",110) being rotatable but arranged stationarily in space and arranged to forcibly rotate with the same rotational speed, e.g. by means of a gear transmission (11,12), and that said first shafts ( 7 ,7',7",107) are interconnected by a linkage system(6,106) being included in the adjustment mechanism and arranged to, upon movement of one of said first shafts a distance along the. periphery of the second gear (9,9',9",109) associated thereto, forcibly move the other shafts an equal distance, thereby ensuring that all first gears(8,108) and thereby all adjustable cog wheels (5,5',5",105,105') always are at the same distance from their common centre irrespective of the absolute length of this distance.

7. Gear drive according to claim 6, c h a r a ct e r i z e d i n that the linkage system(6, 106 ) includes a carrier disc(13,13',13",113,113',113") for each cog wheel (5,5',5",105,105") or each other in- or outwards swingable wheels or glide elements, said discs being swingable around their associated second shaft(10,10', 10", 110) and having the purpose to, at an adjustment operation, move the first shaft (7,7',7",107) in a circular path around the second shaft and that all carrier discs present are mutually connected by articulated links (14,14',14",114,114',114") that, when one disc is swung around a second shaft, forcibly swing the other discs in a similar way.

8. Gear drive according to any one of the preceding claims, c h a r a c t e r i z e d i n that the adjustment mechanism is arranged to cooperate with an automatic rotational speed controlling device ( 48, 49, 50 ) including on one hand a rotatable hub part (.48) with a cam device (49) projecting from the hub and on the other hand one or more weights, e.g., balls or similar(50), being in contact with the inside of the cam device and being arranged to cooperate with a spring-loaded disc part (52) being partially movable along the hub part, more specifically in a way that the weights on one hand under the influence of the centrifugal force are pressed radially outwards along the cam device at increasing rotational speeds at the same time bringing the disc part to move axially in a motion pattern depending on the cam device, and on the other hand return to their inner positions of rest at decreasing rotational speeds, the disc part simultaneously being automatically returned to an initial position by means of the spring(53) in question.

9. Gear drive according to claim 8, c h a r a ct e r i z e d i n that the disc part(52) is connected to a cog track(54) being in engagement with an intermediate gear(55) in turn being engaged with a main gear(55), being arranged to by the means of a bevel .gear drive (57), rotate a shaft (58), possibly being also manually actuable, said shaft being rigidly connected to an adjustment disc (44) having a groove (43) wherein a pin(42) of a carrier device (38) is engaged.

10. Gear drive according to any one of the preceding claims, c h a r a c t e r i z e d i n that the separate, adjustable cog wheel (5 , 40,105) is journalled on a free wheeling hub(41), that on one hand ensures a torsionally rigid connection between the cog wheel and its associated shaft during the rotation of the wheel in a driving direction and on the other hand allows the wheel to idle when the wheel is subjected to a force in the opposite rotational direction, by which means the cogs or teeth of the wheel can remain in a correct engagement with the transmission element(4,31,104) independently of varying adjustment distances between adjacent cog wheels.

11. Gear drive according to claim 2, c h a r a ct e r i z e d i n that the gear drive includes two flexible transmission elements ( 31 , 31') each being in engagement with a plurality of radially adjustable cogwheels (40) and a pair of cog wheels ( 40 , 40A) being connected to a common carrier device (38), each engaging a respective transmission element, and cooperating in such a way that when one wheel moves radially outwards the other wheel simultaneously moves radially inwards.

12. Gear drive according to any one of the preceding claims, c h a r a c t e r i z e d i n that the gear drive is arranged to cooperate with a reversing gear mechanism including first and second shafts ( 60,61) that each are torsionally rigidly connected to cog- or tooth-provided wheels or main wheels (67,69 ) being separated from each other but arranged to cooperate mutually by means of a pair of intermediate wheels (70,71) also provided with cogs teeth, one (71) of said intermediate wheels being rotatably mounted on an arm(72) being suitably handle-resembling and swingable relative to said first shaft(60), the other(70) of said intermediate wheels being rotatably mounted on a second arm(73) being swingable relative to the second shaft (61) and connected to the first arm by means of an articulated link(74), said arms being swingable from on one hand a first position wherein one of the intermediate wheels (71) simultaneously is in engagement with both main wheels (67,69) at the same time that the other intermediate cog wheel (70) is out of engagement with the first intermediate wheel (71) , the two main wheels being made to rotate in one and the same rotational direction, to on the other hand a second position wherein the intermediate wheels (70,71) on one hand are mutually engaged and on the other hand each are in engagement with a respective main wheel (67,69) , the main wheels thus being made to rotate in opposite rotational directions by means of the two intermediate wheels.

13. Gear drive according to any one of the preceding claims, c h a r a c t e r i z e d i n that the gear drive is arranged to cooperate with an input or output power transmission including on one hand two shafts (60, 61) , whereof one(60), works with an essentially constant rotational speed and the second,(61) with a rotational speed that is variable by means of a gear mechanism, and on the other hand a third driven part or output shaft ( 68 ) , that the first shaft ( 60 ) working with constant rotational speed is torsionally rigidly connected to the sun wheel (66) of a planetary gearing whose planetary wheels ( 65, 65', 65" ) are arranged to be driven by a gear (63) being journalled relative to the first shaft (60) and being in engagement with a gear (62) being torsionally rigidly connected to the second shaft(61), and that the ring gear(67) of the gear, possibly by means of a reversing gear mechanism, is drivingly connected (69) to the third output shaft or.part (68).