POWER TRANSMISSION SYSTEM WITH AT LEAST ONE ENGAGEMENT COMPONENT AND DIVIDED GEAR WHEELS

Abstract

The present application relates to a divided gear wheel 100, 200, for a power transmission system 1 of an automotive vehicle, to a power transmission system and a method to operate said power transmission system. The power transmission system comprises at least one divided gear wheel that comprises an inner part 130, 230, being engageable with a shaft and an outer part 110, 210, comprising teeth, adapted for torque transmission to another gear wheel. The inner part and the outer part have a common rotational axis, and the inner part is at least partially arranged within the outer part. Further, the inner part is coupled to the outer part by means of at least a set of two elastic elements, so that the inner part is arranged angularly deflectable with respect to the outer part around the common rotational axis. The inner part and the outer part are adapted to rotate with the same angular speed if the elastic elements are fully loaded.

Claims

1. A divided gear wheel (200), for a power transmission system (1) of an automotive vehicle, wherein the divided gear wheel (200) comprises an inner part (230) being engageable with the assigned shaft (10, 20) and an outer part (232) comprising a gear teething suitable for the provided meshed gear wheel, adapted for torque transmission to/from the other gear wheel, wherein the inner part (230) comprises engagement means (231) that are adapted to engage the inner part (230) with the assigned shaft (10, 20), wherein upon engagement, the inner part (230) is torque proof engaged with the assigned shaft (10, 20), wherein the inner part (230) and the outer part (232) have a common rotational axis, wherein the inner part (230) is at least partially arranged within the outer part (232), wherein the inner part (230) is arranged angularly deflectable with respect to the outer part (232) around the common rotational axis, wherein the inner part (230) is coupled to the outer part (232) by means of at least one set of two elastic elements (252, 253, 254, 255) wherein each set of two elastic elements (252, 253, 254, 255) is received within at least one compartment formed by the inner part (230) and the outer part (232), wherein each set of two elastic elements (252, 253, 254, 255) is positioned in a way that, the first elastic element (253, 255) consisting the set of two elastic elements is initially deformed upon deflection of either the inner part (230) or the outer part (232), with the deformation of the second elastic element (252, 254) consisting the set of two elastic elements, following after the completion of the engagement of the inner part (230) with the assigned shaft (10, 20), wherein the first elastic element (253, 255) and the second elastic element (252, 254) consisting the set of two elastic elements of each set of two elastic elements (252, 253, 254, 255) have different spring constants in relation to each other, with the spring constant of the first elastic element (253, 255) being smaller than the spring constant of the second elastic element (252, 254), wherein the inner part (230) comprises at least one inner support (234) and the outer part (232) comprises at least one outer support (233) that support each set of two elastic elements (252, 253, 254, 255), wherein the first elastic element (253, 255) is in constant contact with the inner support (234) and the outer support (233), wherein the inner part (230) and the outer part (232) are adapted to rotate with the same angular speed if each set of two elastic elements (252, 253, 254, 255) is fully loaded under the occurring load.

2. A power transmission system (1), of an automotive vehicle, comprising: an input shaft (10), supporting input gear wheels (100, 200); an output shaft (20), supporting output gear wheels (100, 200), wherein each of the input gear wheels (100, 200) engages with a corresponding output gear wheel (100, 200), thereby defining a gear ratio, wherein at least one of the input gear wheels (100, 200) and/or at least one of the output gear wheels (100, 200) of a gear ratio is a divided gear wheel (200) according to claim 1; and at least one engagement component (320), assigned to at least one of the shafts (10, 20) and to at least one divided gear wheel (200), wherein the at least one engagement component (320) is torque proof engaged with the assigned shaft (10, 20), configured axially movable along the assigned shaft (10, 20), wherein the engagement means (330) of the at least one engagement component (320) are adapted to engage with/disengage from the engagement means (231) of the inner part (230) of the divided gear wheel (200) thereby torque proof fixing/unfixing the inner part (230) with the assigned shaft (10, 20).

3. The power transmission system (1) according to claim 2, wherein the at least one engagement component (320) is arranged concentrically to the assigned shaft (10, 20), and has engagement means (330) adapted to engage with/disengage from the engagement means (231) of the inner part (230) of the divided gear wheel (200), thereby torque proof fixing/unfixing the inner part (230) with the assigned shaft (10, 20), wherein the at least one engagement component (320) is torque proof engaged with the assigned shaft (10, 20) and can slide axially with the help of at least one shifting mechanism (400), guided by guiding means (350) due to the interaction of the guiding means (350) with the corresponding engagement means (360) of the engagement component (320), wherein the corresponding engagement means (360) of the engagement component (320) are shaped with respect to the form of the guiding means (350).

4. The power transmission system (1) according to any of claims 2 to 3, comprises at least one engagement component (320) with the engagement means (330) being adapted to engage with the corresponding engagement means (231) of the inner part (230) of the divided gear wheel (200), wherein the engagement means (330) are provided in accordance to the selected position of the corresponding engagement means (231) of the inner part (230) of the divided gear wheel (200), and have a suitable form in order to deliver the engagement/disengagement.

5. The power transmission system (1) according to any of claims 2 to 4, wherein at least one gear ratio of the power transmission system (1) is defined by two divided gear wheels (200), according to claim 1, where the inner part (230) of the one divided gear wheel (200) is torque proof engaged with the assigned shaft (10,20) and the other inner part (230) of the other divided gear wheel (200) defining a gear ratio is engageable upon interaction with an assigned engagement component (320).

6. The power transmission system (1) according to any of claims 2 to 5, comprises jackshafts with gear wheels, wherein every gear wheel of the at least one jackshaft engages both the input gear wheels (100, 200) and the output gear wheels (100, 200).

7. The power transmission system (1) according to any of claims 2 to 6, further comprising at least one shifting mechanism (400) with a shift actuator, adapted to axially move the at least one engagement component (320), to select/deselect a gear ratio.

8. The power transmission system (1) according to any of claims 2 to 7, further comprising a control unit, position sensors and measuring instruments taking according measurements and providing them to the control unit, which is adapted to command a gear ratio changing action with the provision of respective commands to at least one shifting mechanism (400) after assessing and processing the provided data.

9. A method for operating a power transmission system (1) according to any of claims 2 to 8, the method comprising the following steps: rotating the input shaft (10) and transferring power to the output shaft (20) by means of an initial gear ratio; commanding a gear ratio changing action with the provision of respective commands to at least one shifting mechanism (400), after assessing and processing data in a control unit, from the initial gear ratio to a consecutive gear ratio; axially moving at least one engagement component (320) and thereby engaging the at least one engagement component (320) to the at least one inner part (230) of the at least one divided gear wheel (200) of the consecutive gear ratio, thereby torque proof fixing the at least one divided gear wheel (200) of the consecutive gear ratio with the assigned shaft, axially moving at least one engagement component (320) and thereby disengaging the at least one engagement component (320) from at least one inner part (230) of the at least one divided gear wheel (200) of the initial gear ratio, rotating the input shaft and continuously transferring power to the output shaft during the gear changing action, until the entire power is transferred by means of a new gear ratio.

10. The method according to any of the claims 2 to 9, wherein the form of the guiding means (350) forces the torque proof engaged with the assigned shaft (10,20), engagement component (320) to rotate, when moved axially by the shifting mechanism (400), assisting the engagement between the engagement component (320) and the inner part (230) of the divided gear wheel (200).

11. An automotive vehicle comprising a divided gear wheel (200) according to claim 1 or a power transmission system (1) according to any one of claims 2 to 10.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0073] In the following, preferred embodiments of the present invention are described with respect to the accompanying figures.

[0074] FIG. 1 is a schematic illustration of a section cut of a gear ratio of a power transmission system according to a first embodiment;

[0075] FIG. 2 is a schematic illustration of a section cut of a power transmission system according to a first embodiment;

[0076] FIG. 3 is a schematic perspective exploded view of a dog clutch of a power transmission system according to a first embodiment;

[0077] FIG. 4 is a schematic perspective view of an inner and outer part of a divided gear wheel according to a first embodiment;

[0078] FIG. 5A to C give a schematic illustration of a gear ratio changing action sequence;

[0079] FIG. 6D to F give a schematic illustration of a gear ratio changing action sequence;

[0080] FIG. 7 is a schematic illustration of a power transmission system according to an alternative configuration;

[0081] FIG. 8 is a schematic perspective exploded view of an engagement component, an assigned shaft and divided gear wheel of a power transmission system according to an alternative configuration;

[0082] FIG. 9A to B is a schematic illustration of a power transmission system according to an alternative configuration;

[0083] FIG. 10 is a schematic perspective view of a shifting mechanism of a power transmission system according to the previously mentioned configurations;

[0084] FIG. 11 is a schematic detail illustration of the engagement means of individual parts of a power transmission system according to the previously mentioned configurations;

[0085] FIG. 12 is a schematic detail illustration of the engagement means of individual parts of a power transmission system according to the previously mentioned configurations;

DETAILED DESCRIPTION

[0086] As will become apparent from the following, the present application allows to provide a power transmission system that delivers power smoothly and continuously to the wheels when upshifting, without power losses from friction between clutch disks, due to the absence of clutch disk disengagement/engagement in every gear ratio changing action following the first gear ratio.

[0087] FIG. 1 is a schematic illustration of a gear ratio of a power transmission system 1, defined by a divided gear wheel 200 comprising four spring elements in two spring compartments, supported by the output shaft 20, engaged with a gear wheel 100 supported by the input shaft 10.

[0088] The divided gear wheel 200 is consisted of an outer part 232 and an inner part 230 connected to one another by means of four springs 252, 253, 254, 255. The inner part 230 and the outer part 232 have a common rotational axis, and the inner part 230 is at least partially arranged within the outer part 232. Further since two sets of two elastic elements 252, 253, 254, 255 are adapted to couple the inner part 230 and the outer part 232, the inner part 230 is angularly deflectable with respect to the outer part 232 and vice versa.

[0089] The outer part 232 of the divided gear wheel 200 has a gear teething 215 on its outer circumference, able to transfer rotational force and/or torque. This gear teething 215 is constantly meshing with the gear teething 115 of the gear wheel 100 which is supported by the input shaft 10 and is constantly engaged with the shaft 10.

[0090] The inner part 230 is not constantly engaged with the output shaft 20, but can be torque proof engaged with the shaft only when the engagement means 231 of the inner part 230 interact with the engagement means (teeth) 330 of the engagement component 320 as will be described in further detail later on.

[0091] Both inner part 230 and outer part 232 have two spring supports 233, 234, supporting the four springs 252, 253, 254, 255, which are preferably integrally formed with the outer part 232 or the inner part 230, respectively.

[0092] The four springs 252, 253, 254, 255, are received in spring compartments, formed by the inner part 230 and the outer part 232. In this exemplary illustration, two sets of two elastic elements, housed in two spring compartments, are adapted as elastic elements, distributed around the inner circumference of the outer part 232. Each set of spring elements is consisted by two spring elements and the first spring element 253 is positioned concentrically to the second spring element 252 which has increased diameter in relation to the first spring element 253. In addition the first spring element 253 protrudes out of the second spring element 252 on a front face and the first spring element 253 has a lower spring rate than the second spring element 252. An analogous configuration is adapted for the other set of spring elements, where the “softer” spring element is the 255 and the “stiffer” is the 254. This “softer” spring assists with an easier, smoother engagement/disengagement between the engagement component 320 and the inner part 230 of the divided gear wheel 200, and provides the needed time in order to fully engage/disengage the engagement component 320 and the inner part 230 of the divided gear wheel 200.

[0093] In the presented exemplary configuration, all of the spring elements 252,253,254,255 will compress no matter how the rotating components rotate in relation to each other (clockwise or counterclockwise). Various design approaches can be adapted, always following the basic principle behind the innovation, where the spring elements will be lengthened instead of being compressed. Furthermore additional or fewer sets of elastic elements can be incorporated to the design, with a corresponding redesign of the inner part 230 and the outer part 232.

[0094] The inner part 230, also comprises engagement means 231 on its front face where the engagement means (teeth) 330 of the engagement component 320, engage and thereby torque proof fixing the inner part 230 to the output shaft 20. The engagement means 231 in this exemplary configuration are on the front face of the inner part 230. In another alternative configuration the engagement means 231 can be on the inner circumference of the inner part 230 of the divided gear wheel 200. Furthermore the engagement surfaces between the two components can be angled resulting in smoother, easier disengagement, but in any case both engaging surfaces between the engaging parts will be corresponding to each other. Upon engagement, the inner part 230 and the output shaft 20, will be torque proof engaged. The inner part 230 and the outer part 232 of the divided gear wheel 200, rotate with the same angular velocity, when the springs 252,253,254,255 are fully loaded.

[0095] In the presented configuration, a gear ratio is defined by one divided gear wheel 200 and one gear wheel 100, constantly meshing via gear teeth 215 and 115 respectively. The divided gear wheel 200 is engageable with the output shaft 20, engaged upon engagement with the engagement means (teeth) 330 of the engagement component 320. The engagement means (teeth) 330 are not visible in the presented figure but a more clear view follows in FIGS. 2 and 3. The gear wheel 100 is constantly engaged with the input shaft 10 and power can be transferred from one shaft to the other only when the inner part 230 of the divided gear wheel 200, is engaged with the engagement component 320. Power is transferred via the selected gear ratio, from the moment the engagement component 320 engages to the inner part 230 of the divided gear wheel 200. Even when the softer springs compress, a small amount of power is transferred to the system. The springs 252,253,254,255 do not have to be fully loaded in order to transfer torque, but upon full load, both inner part 230 and outer part 232 of the divided gear wheel 200, rotate with the same angular velocity. It is going without saying that both gear wheels forming a gear ratio can be divided gear wheels, resulting in additional features for the configuration. In this scenario, both gear wheels will be divided gear wheels but again one gear wheel will be constantly engaged with the assigned shaft and the other will be free to rotate when not engaged, transferring power only upon engagement with corresponding engagement means. In other words, the inner part of the free divided gear wheel will be engageable with the shaft and the inner part of the other divided gear wheel forming a gear ratio will be constantly engaged with the assigned shaft.

[0096] FIG. 2 is a schematic illustration of a horizontal section cut of a gear ratio of a power transmission system 1, illustrating two consecutive gear ratios.

[0097] In this depiction, only two consecutive gear ratios are depicted but it is going without saying that the configuration can comprise more than two gear ratios in an analogous layout. In addition all the free divided gear wheels of the configuration, are supported by the output shaft 20. The same goes with the dog clutch 300. In another alternative configuration the free divided gear wheels (and the dog clutches) can alternate to the input shaft 10 and the output shaft 20. In any case and for the presented exemplary layout, as mentioned before, each gear ratio is defined again by a set of a free divided gear wheel and a constantly engaged gear wheel (can be a divided gear wheel as mentioned before).

[0098] From this depiction, the positioning of the dog clutch 300 for the presented configuration, is clearer. The dog clutch 300 is in between the presented divided gear wheels (or gear wheels in general when the engageable gear wheels alternate on the input and output shafts) and is consisted by a dog clutch hub 310 and two engagement components 320 providing the engagement means (teeth) 330 which engage to the inner parts 230.

[0099] The dog clutch hub is constantly engaged with the assigned shaft (in this configuration the assigned shaft is the output shaft 20) and the engagement component 320 are able to slide axially, engaging or disengaging to the according inner part. Both engagement components 320 are torque proof engaged (but can slide axially) to the dog clutch hub 310 and the face of the one engagement component faces the one gear ratio, while the face of the other engagement component faces the other gear ratio. In addition the engagement components 320, have shifting fork grooves 321 on their outer circumferential surface that house the shifting forks 410, that adjust the axial (in relation to the axis of the assigned shaft) position of the engagement components 320, with the help of a shifting mechanism(s).

[0100] As can be seen from this horizontal section cut, gear ratio “a” is selected, since the engagement component 320a is engaged with the inner part 230a. By this engagement the inner part 230a of the divided gear wheel 200a is torque proof engaged with the output shaft 20 (i.e. both output shaft 20 and inner part 230a rotate with the same angular velocity). When springs 252a, 253a, 254a, 255a are fully loaded, both inner part 230a and outer part 232a will rotate with the same angular velocity, and torque transfer will be accomplished exclusively via gear ratio “a” (only one engagement component 320 is engaged with the inner part 230 in the entire configuration, i.e. the gear changing action has been completed).

[0101] As can be seen, when the engagement component 320a is engaged with the inner part 230a and the gear ratio changing action is completed, every other engagement component 320 will be disengaged. During gear ratio changing actions, more than one engagement component 320 might be engaged with the corresponding inner parts 230.

[0102] In this portrayal, the engagement component 320a, is assigned to engage (and is presented as engaged) with the inner part 230a. The engagement takes places with the interaction between the engagement means (teeth) 330a, positioned on the front face of the engagement component 320a and the corresponding engagement means 231a, positioned on the front face of the inner part 230a.

[0103] As a person skilled in the art understands, in order to upshift (change gear from gear ratio “a” to gear ratio “b”), the engagement component 320a will remain engaged with the inner part 230a as the engagement component 320b is moved axially by the corresponding shifting mechanism(s) [the shifting mechanism(s) is controlled by a Central Processing Unit, that after taking account of certain parameters and fed data, commands the shifting mechanism to perform a gear changing action]. When the engagement means (teeth) 330b of the engagement component 320b, initiate to interact with the engagement means 231b of the inner part 230b of the divided gear wheel 200b, the springs 253b and 255b (which are longer and have smaller spring rate in relation to springs 252b and 254b, i.e. springs 252b and 254b are stiffer) will start to compress. At this moment the engagement component 320a is still engaged with the inner part 230a and most of the power is transferred via gear ratio “a” (a relatively small amount of power is transferred from gear ratio “b”, since it is partially engaged with the shaft and the “softer” springs have started to compress). The softer spring elements 253b and 255b, compress initially by the interaction of both inner part 230b and outer part 232b of the divided gear wheel 200b and the compression of the stiffer spring elements 252b and 254b follows. When the stiffer spring elements 252b and 254b compress, the softer spring elements 253b and 255b continue to compress as well, due to the positioning of the four spring elements (252b, 253b, 254b, 255b). As the load being borne by the springs of gear ratio “b” progresses, the load being borne by the springs of gear ratio “a”, decreases, and when the springs of the gear ratio “a” are unloaded, the CPU commands the shifting mechanism(s) to disengage the engagement component 320a. The “softer” springs provide time, so that the engagement component 320, engages completely with the inner part 230 of the divided gear wheel 200.

[0104] In order to downshift (change gear from gear ratio “b” to gear ratio “a”), the general outline is generally the same as descripted above. The engagement component 320b is now engaged with the inner part 230b of the divided gear wheel 200b, and the engagement means (dog clutch ring teeth) 330b interact with the engagement means 231b. According measurements are taken from according sensors and a gear changing action takes place [again with the help of a Central Processing Unit and corresponding shifting mechanism(s)].

[0105] The moment a downshifting action is commanded, a simultaneous command is being given to the engine in order to momentarily interrupt the power, and the disengagement of the engagement component 320b from the inner part 230b initiates, with a simultaneous engagement of the engagement component 320a to the inner part 230a. When the engagement/disengagement has been completed (linear position sensors will assists, by defining the linear position of the engagement components), the engine will continue supplying power depending on the position of the gas pedal (when the engagement/disengagement is completed, the power supply in relation to the accelerator pedal will follow).

[0106] The gear ratios “a” and “b” are exemplary gear ratios. The operation is analogous to any consecutive gear ratio in a power transmission system.

[0107] In both upshifting and downshifting, as previously mentioned, a Central Processing Unit (CPU) is the one that commands the shifting mechanism(s) to move the desired engagement component 320 in order to engage (or disengage) to the corresponding inner part 230 [via the engagement means (teeth) 330] of the divided gear wheel 200. The CPU takes account of different measurements (e.g. engine's revolution, vehicle velocity, selected gear ratio, linear position of the engagement component etc.) from according measuring instruments before commanding the gear changing action. The driver can manually command a gear changing action (for example by pressing a button).

[0108] As can be understood from the above description in both cases (upshifting and downshifting) when the gear changing action is completed, only one inner part 230 is engaged with the assigned shaft (in the presented configuration output shaft 20) via engagement component 320. During the gear changing action, more than one engagement components 320 can at least be partially engaged with their assigned inner parts 230.

[0109] FIG. 3 is a schematic illustration of the components consisted the dog clutch 300 in an exploded perspective layout.

[0110] More specifically the dog clutch 300 is consisted by three main components. The first is the dog clutch hub 310 and the other two are engagement components 320, housed to the hub, opposing to each other (i.e. the face of the one engagement component 320a “meets” the one face of the dog clutch hub and the other face of the other engagement component 320b “meets” the other). The dog clutch hub 310 is constantly engaged with the assigned shaft, for example with splines on the inner circumference as depicted in this view. The engagement components 320 are housed to the dog clutch hub 310, constantly interacting with the dog clutch hub 310 and guided by guiding means 350 which are positioned on the outer circumferential surface of the dog clutch hub 310. By the constant interaction of the engagement components 320 with the dog clutch hub 310, both parts are torque proof engaged and rotate with the same angular velocity. Since the dog clutch hub 310 is constantly engaged with the assigned shaft (i.e. rotates with the same angular velocity), both the assigned shaft, the dog clutch hub 310 and the housed engagement components 320 are torque proof engaged and rotate with the same angular velocity. In addition both engagement components 320 can be moved axially by shifting mechanism(s) resulting in engagement (or disengagement) with the assigned part (inner part of the divided gear wheel). The shifting fork(s) 410 are engaged in a rotationally free manner with the engagement components 320a, 320b.

[0111] In the presented layout the guiding means—channels 350 are presented as linear grooves/splines (it is obvious that can be either protrusions or cavities). In another alternative guiding means—channels 350 can be shaped as helixes (i.e. formed in a shape similar to a helical gear) with a corresponding change in engagement means 360. As a person skilled in the art understands, in that case, engagement components 320, in addition to the axial movement, will also have a rotational one. As a result when the shifting mechanism(s) pulls (or pushes) the corresponding engagement component 320 in order to engage (or disengage), the engagement component will have an additional angular velocity (increasing or decreasing the angular velocity of the engagement component 320 in relation to the angular velocity of the assigned shaft) depending on how fast (or slow) shifting mechanism(s) actuates the engagement component 320 and the helix characteristics, in order to achieve equal angular velocities between the engaging components (i.e. engagement component 320 and inner part 230 of the divided gear wheel 200). By this feature smoother engagement between the engaging components can be achieved since the engaging components will have same (or similar) angular velocities. The guiding means—channels 350 interact with the engagement means 360 of the engagement component 320, allowing axial (or axial and rotational) movement to the engagement component 320 with constant engagement to the dog clutch hub 310.

[0112] Additionally the engaging surfaces 340 can be angled assisting the disengagement (or engagement) of the engagement component 320. It is going again without mentioning that all the changes adapted by the engagement means (teeth) 330 are always made in relation, and with analogous changes, to the engagement means 231 of the inner part 230 of the divided gear 200, resulting in perfect match upon engagement.

[0113] In addition every engagement component 320 has a shifting fork groove 321 that houses the assigned shifting fork 410. The shifting fork 410 is not rotatably connected to the engagement component 320 (i.e. the engagement component 320 can rotate with the shifting fork 410 not following the rotation). The shifting fork protrusion 411 is guided in a way that the shifting fork 410 is axially moved, in relation to the axis of the assigned shaft. Since the shifting fork 410 is attached to the engagement component 320, the two are axially (in relation to the axis of the assigned shaft) moved together.

[0114] FIG. 4 is a schematic illustration of the inner part 230 and the outer part 232 of the divided gear wheel 200 in a perspective layout.

[0115] In this depiction, the engagement means 231 of the inner part 230 of the divided gear wheel 200 can be seen. As mentioned before the engagement means 231 are in accordance with the engagement means (teeth) 330 of the engagement component 320. The engagement means 231 of the inner part 230 are presented as recesses since the engagement means (teeth) 330 of the engagement component 320 have been previously presented as protrusions. In addition the number of recesses and protrusions (or vice versa, or a combination of both in alternative designs) between the two engaging components are in accordance to each other (As a person skilled in the art understands the number of engagement means 231 do not have necessarily be equal with the engagement means (teeth) 330). Furthermore as mentioned before the engaging surfaces are in relation to each other. If, for example, the engaging surfaces 340 of the engagement means (teeth) 330 are perpendicular, in relation to the face of the engagement component 320, the engaging surfaces 241 of the inner part 230 of the divided gear wheel 200 will again be perpendicular in relation to the face of the inner part 230.

[0116] In addition in this exemplary configuration spring support 234 of the inner part 230 of the divided gear wheel 200, is positioned between the two elements consisting spring support 233 of the outer part 232 of the divided gear wheel 200, and as a result the two parts (inner part 230 and outer part 232, do not collide to each other). It is going without saying that other forms for both spring supports 233, 234 can be adopted.

[0117] FIG. 5A to C give a schematic illustration of a gear ratio changing action sequence, using random numbers and random gear ratios. More particularly there is an upshifting gear ratio changing action from gear ratio “a” to gear ratio “b”. For this example a heavy vehicle (e.g. truck), with the following gear ratios: gear ratio “a”=6.05, gear ratio “b”=5.16 are selected and the numbers are integral. It is going without saying that the two gear ratios presented are not the only gear ratios of the automotive power transmission system, but are presented in order to explain the gear changing action.

[0118] In this set of figures two gear ratios (four gear wheels in total) are presented with a dog clutch 300 in between them in accordance to the previously mentioned layouts. The divided gear wheels 200a and 200b are supported by the output shaft 20 and the gear wheels 100a and 100b are supported by the input shaft 10. Each gear ratio is formed by one divided gear wheel 200 and one gear wheel 100, constantly meshing to each other but can transfer torque to the output shaft 20 only when the divided gear wheel 200 is engaged with the output shaft 20 with the help of dog clutch 300 (engagement components 320 are presented as bold lines, one for each gear ratio). As a consequence gear ratio “a” is formed by divided gear wheel 200a and gear wheel 100a and gear ratio “b” by divided gear wheel 200b and gear wheel 100b.

[0119] In FIG. 5A the divided gear wheel 200a is torque proof engaged with the output shaft 20 and gear ratio “a” is selected. At this moment the divided gear wheel 200b is disengaged and rotates, due to the fact that it is meshing with the constantly engaged (to the input shaft) gear wheel 100b. As mentioned before the gear wheels 100a and 100b are constantly engaged with the input shaft 10 and the divided gears 200a and 200b can rotate freely when they are not engaged with the output shaft 20 (with the help of the dog clutch 300), but are torque proof engaged with the output shaft 20 upon engagement. The input shaft 10 rotates, for example, with 1700 revolutions per minute (rpm) and the output shaft 20 rotates with 281 rpm due to the fact that gear ratio “a” is selected (i.e. dog clutch 300 is engaged to gear ratio “a”). Divided gear 200b rotates with 330 rpm, but does not transfer torque to the assigned shaft, since is not engaged with the shaft via an engagement component 320b. The divided gear wheel 200b rotates due to the fact that is constantly meshing with gear wheel 100b, which rotates with 1700 rpm, since is constantly engaged with the input shaft 10.

[0120] Springs 250 are fully loaded in both gear ratios “a” and “b”, but the springs 250a are fully compressed (since gear ratio “a” is selected), and the springs 250b are decompressed (since gear ratio “b” is not engaged with the dog clutch 300). In either case (decompression or fully compression) the springs 250 are fully loaded. The difference between the two conditions is the occurring load that results in the according compression. In the case that the spring 250a is fully compressed, the applied load to the spring is great, resulting in larger deformation/compression. In gear ratio “b” the spring is, again fully loaded, but not compressed due to the fact that the applied load is minimum as a result of the unengaged, free to rotate divided gear wheel. As a person skilled in the art understands, the springs of the unengaged free to rotate divided gear wheel, might compress slightly due to the interaction between the connected (via the springs) components (bearing losses, meshing teeth friction, inertia), but since there is no significant resistance (by the unengaged inner part of the divided gear wheel) the term fully decompressed is used. In addition the term fully loaded or fully compressed is used when the springs have altered their length (lengthened or shortened) under the occurring load and the disfigurement is completed.

[0121] As can be seen in FIG. 5B a gear changing action (from gear ratio “a” to gear ratio “b”) is commanded and after certain processes in the CPU, the engagement component 320b assigned to the divided gear wheel 200b is moved by a shifting mechanism and engages with the inner part 230b. The engagement component 320a assigned to the divided gear wheel 200a is still engaged with the inner part 230a of the divided gear wheel 200a. As a consequences both inner parts 230 of the divided gear wheels 200a and 200b are engaged with the output shaft 20 via their assigned engagement components 320 (e.g. dog clutch rings).

[0122] Now the inner part 230b of the divided gear wheel 200b, rotates with 281 rpm since is now torque proof engaged with the assigned output shaft 20 due to the dog clutch engagement. Since the input rotations from the engine is 1700 rpm and the outer part 232b of the divided gear wheel 200b rotates with 330 rpm, springs 250b inside the divided gear wheel start to compress bearing load.

[0123] As a person skilled in the art understands, as the time passes, the load being borne by the springs 250b inside the divided gear wheel 200b increases and at the same time the load being borne by the springs 250a inside the divided gear wheel 200a decreases.

[0124] At this moment, both inner parts 230a, 230b of the divided gear wheels 200a, 200b are engaged with the output shaft 20, and therefore power is transferred via both gear ratios “a” and “b”. As it is obvious, as the time passes, more power is delivered to the output shaft 20 via gear ratio “b” and less via gear ratio “a”.

[0125] An intermediate moment is presented in FIG. 5B in which, for example, inner part 230b of the divided gear wheel 200b rotates with 281 rpm, outer part 232b of the divided gear wheel 200b rotates with 310 rpm and gear wheel 100b rotates with 1600 rpm. In addition the inner part 230a of the divided gear wheel 200a rotates with 281 rpm and gear wheel 100b rotates with 1600 rpm.

[0126] As can be seen due to the difference in angular velocities between the inner parts 230a, 230b of the divided gear wheels 200a, 200b and the angular velocities between their coupled outer parts 232a, 232b of the divided gear wheels 200a, 200b, springs 250a decompress and springs 250b compress.

[0127] When all of the power from the input shaft 10 is delivered to the output shaft 20 via gear ratio “b” the springs 250a inside the divided gear wheel 200a of gear ratio “a” will be fully decompressed and the disengagement of the inner part 230a of the divided gear wheel 200a can take place.

[0128] In FIG. 5C all of the power is delivered to the output shaft 20 via gear ratio “b”, and as a result springs 250a inside the divided gear wheel 200a are fully decompressed. The CPU is aware of the nearly fully decompressed springs 250a, due to the fact that corresponding position sensors are adapted, and as a consequence, commands a disengagement action to begin, disengaging the inner part 230a of the divided gear wheel 200a.

[0129] Now all of the power is delivered via gear ratio “b”. The inner part 230b and the outer part 232b of the divided gear wheel 200b rotate with 281 rpm. In addition gear wheel 100b rotates with 1450 rpm and so does the gear wheel 100a and the engine. Divided gear wheel 200a is ungagged and therefore free to rotate, rotating with 240 rpm due to the meshing with gear wheel 100a.

[0130] As can be seen from the above the gear changing action is completed and now the power is transferred via gear ratio “b”, with a continuous, smooth, uninterrupted power transfer from gear ratio “a” to gear ratio “b” and with a corresponding “drop” of rpm to the engine (from the initial 1700 to 1450).

[0131] In FIGS. 6D to 6F an example for a gear changing action for a heavy vehicle (e.g. truck) is presented and more specifically a downshifting gear changing action (i.e. from gear ratio “b” to a lower gear ratio “a”).

[0132] The configuration is similar to the one described in FIGS. 5A to 5C.

[0133] As can be seen in FIG. 6D the inner part 230b of the divided gear wheel 200b is engaged with the output shaft 20 and the divided gear wheel 200a is disengaged and as a result free to rotate. As a consequence gear ratio “b” is selected and the output is 271 rpm with an input of 1400 rpm. Both the gear wheels 100a and 100b rotate with 1400 rpm (due to the constant engagement to the input shaft 10).

[0134] Springs 250a are fully decompressed and springs 250b are fully compressed. Inner part 230a and outer part 232a of the divided gear wheel 200a rotate with 231 rpm and inner part 230b and outer part 232b of the divided gear wheel 200b rotate with 271 rpm, due to their meshing with gear wheels 100a and 100b respectively.

[0135] A gear changing action from the selected gear ratio “b” to the previous gear ratio “a” (downshifting) is commanded by the CPU.

[0136] In FIG. 6E the downshifting action has initiated. CPU commands the engine to a power cut (idling). As a result springs 250b inside the divided gear wheel 200b start to decompress and a disengagement command (from the CPU) can initiate, in order to disengage the inner part 230b of the divided gear wheel 200b. As mentioned before CPU acknowledges that the disengagement is completed from the data acquired by the linear position sensors. At the same time an engagement command (from the CPU) can take place, engaging the inner part 230a of the divided gear wheel 200a with the assigned engagement component 320a and power from the engine is resumed, in relation to the position of the gas pedal.

[0137] As a result the inner part 230a of the divided gear wheel 200a rotates with 271 rpm. Since the accelerator pedal is pressed, engine's revolutions increase (input rpm), and as a result the outer part 232a of the divided gear wheel 200a increases its revolutions until reaching 271 rpm. Due to that, springs 250a inside the divided gear wheel 200a begin to compress.

[0138] In FIG. 6F the engagement/disengagement has been completed and now both inner part 230a and outer part 232a of the divided gear wheel 200a rotate with 271 rpm and springs 250a inside the divided gear wheel 200a are compressed. As a consequence the input shaft 10 rotates with 1641 rpm, gear wheels 100a and 100b rotate also with 1641 rpm and both inner part 230b and outer part 232b of the divided gear wheel 200b rotate with 318 rpm with springs 250b inside the divided gear wheel 200b being decompressed. Therefore gear ratio “a” is selected with the divided gear wheel 200a engaged with the assigned output shaft 20 and the divided gear wheel 200b disengaged and as a result free to rotate.

[0139] In FIG. 7 an alternative configuration of a power transmission system 1′ is presented, in which the engagement component 320 is directly supported on the assigned shaft (absence of dog clutch hub) and one engagement component 320 is assigned to multiple divided gear wheels. The axial movement of the engagement component 320 by according shifting mechanism(s), engages (or disengages) the inner part 230 of the divided gear wheels 200, and therefore a gear ratio is selected.

[0140] The main principles behind this alternative configuration is the same as previously described, where a gear ratio is defined by a set of gear wheels in which at least one gear wheel is a divided gear wheel as described above. In every gear ratio one gear wheel is engageable (engaged upon interaction with the engagement component 320) to the assigned shaft and the other is constantly engaged with the assigned shaft (as mentioned before in an alternative configuration both gear wheels consisting a gear ratio can be divided gear wheels with the one divided gear wheel constantly engaged with the assigned shaft and the other engageable, free to rotate when not engaged). As mentioned before the engageable gear wheel can rotate freely, without transferring torque to the assigned shaft when it is not engaged (to the assigned shaft). The engageable gear wheel is the divided gear wheel.

[0141] In this alternative the engagement component 320 is not in between the divided gear wheels but it is, exemplarily, positioned before the gear ratio “b”, as defined by the interaction of gear wheel 100b and divided gear wheel 200b. Output shaft 20 supports output gear wheels 200a, 200b and input shaft 10 supports input gear wheels 100a, 100b. Input gear wheels 100a, 100b are constantly engaged with the assigned input shaft 10 and divided gear wheels 200a, 200b are engaged with the assigned output shaft 20 by interacting with engagement component 320.

[0142] Engagement component 320, is axially pushed (or pulled) by according shifting mechanism(s) (with the assistance of a CPU as previously described) and is guided by guiding means 350, which are integrally formed to the output shaft 20 which are (exemplarily) presented as linear grooves (in yet another alternative the grooves can be helical with an analogous operation as previously described, in the guiding means of the dog clutch hub 310, i.e. additional angular velocity upon axial displacement).

[0143] As can be seen in more detail in FIG. 8, engagement component 320 is consisted by a bushing portion 371 and at least one engagement component arm 380 extending from the bushing portion 371 and, provided at the distal end, corresponding engagement means (teeth) 330, which are adapted to engage with the engagement means 231 of the inner part 230 of the divided gear wheel 200. Engagement component 320 is torque proof engaged with the assigned output shaft 20 (for example with the help of engagement means 360 on the inner circumference of the bushing portion 371) but can be axially moved [by shifting mechanism(s)]. It is guided (due to the interaction with the engagement means 360) by guiding means 350 (linear as presented or helical in an alternative) integrally formed to the output shaft 20 and engagement means (teeth) 330 adapted to engage with the engagement means 231 of the inner part 230 of the divided gear wheel 200.

[0144] As a person skilled in the art understands, the engagement means (teeth) 330 of the engagement component 320, have a length suitable for engaging the inner parts 230. In this alternative for every gear change, a momentarily power interruption from the engine should take place. Alternatively an increased power supply in the shifting mechanism(s) is needed in order to actuate the engagement component (for upshifting or downshifting) as a person skilled in the art understands.

[0145] In addition the engagement means 231 are not positioned on the front face of the inner part 230 of the divided gear wheel 200, but are on the inner circumference of the inner part 230. In this alternative the number of engagement means 231 do not have necessarily be in relation to the engagement means (teeth) 330. For example the number of engagement means 231 provided by the inner part 230 can be greater than the number of engagement means (teeth) 330 provided by the engagement component 320, resulting in an easier engagement between the two components.

[0146] In addition a set of shaft bearings 221 are provided in order to facilitate the rotation of the inner part 230 in relation to the assigned output shaft 20, and are positioned in between the components, one on each side of the divided gear wheel 200. As it is obvious the inner ring of shaft bearings 221 is shaped in accordance to the engagement component 320 in order to permit the movement of the component, by which the engagement of the inner part 230 of the divided gear wheel 200 is achieved.

[0147] In FIG. 9A to B an alternative configuration, similar to the one presented in FIGS. 7 and 8 is presented.

[0148] As can be seen in FIG. 9A the alternative configuration is pretty much alike to the one presented in FIGS. 7 and 8, but in this configuration every gear ratio is consisted by two divided gear wheels 200, 200′, with the divided gear wheel 200 supported by the output shaft 20 and the divided gear wheels 200′ supported by the input shaft 10. Furthermore the divided gear wheel 200′ is provided as a free divided gear wheel and the divided gear wheel 200 is provided as engaged divided gear wheel, with the inner part 230 torque proof engaged with the assigned output shaft 20. As a consequence each gear is consisted by one engageable free to rotate (when is not engaged with the assigned input shaft 10) divided gear wheel and one engaged with the assigned output shaft 20 divided gear wheel 200. In addition the guiding means 350′ are provided as helical guiding means (instead of the previously described linear) with an according modification in the engagement component 320′, that is assigned to the input shaft 10 instead of the output shaft 20 as described in the previous alternative configuration of FIGS. 7 and 8.

[0149] As can be seen the engagement component 320′ is torque proof engaged with the assigned input shaft 10, axially movable and able to be engaged with the inner parts 230′ of the divided gear wheels 200′ depending on the needs. Upon engagement the inner part 230′ of the divided gear wheel 200′ is torque proof engaged with the assigned input shaft 10.

[0150] As a person skilled in the art understands, due to the helical guiding means 350, when the input shaft 10 rotates, an axial (in relation to the main axis of the input shaft 10) force pushes the engagement component 320′ towards the next gear ratio, and therefore assisting with the engagement of the engagement component 320′ and the assigned inner pars 230′ of the divided gear wheels 200′ when upshifting.

[0151] In contrast when we want to downshift the method is similar to the previously described one.

[0152] FIG. 9B depicts a more clear view of the divided gear wheels 200′ of gear ratios “a” and “b” in which the position of the shaft bearings 221′ and the inner part bearings 222′ is clearer. As can be seen shaft bearings 221′ (consisted of a set of bearings, one on each face of the divided gear wheel 200) are positioned between the inner part 230′ of the divided gear wheel 200′ and the assigned input shaft 10, and inner part bearings 222′ between the inner part 230′ and the outer part 232′ of the divided gear wheel 200′. The layout of the divided gear wheels 200 is analogous to the one of divided gear wheels 200′. It is worth mentioning that the inner ring of shaft bearings 221′ is shaped with respect to the shape of engagement component arms 380′ (which are shaped according to the formation of guiding means 350′) and to the engagement means 330′ of the engagement component 320′, in order the engagement component 320′ to be able to pass through the shaft bearings 221′, engaging/disengaging the inner part 230′ of the divided gear wheels 200′.

[0153] FIG. 10 presents an exemplary shifting mechanism 400 with respect to all the previously presented configurations. As can be seen the exemplary shifting mechanism 400 (it is going without saying that other mechanisms can be adapted) is consisted by a step motor 401 that can rotate (in both directions) the worm shaft 402 and a worm wheel 403, meshing with the worm shaft 402. The worm wheel 403 is torque proof engaged to a splined shaft 406 that supports barrel cams 404 (i.e. when the worm wheel rotates, so does the barrel cams due to the fact that it is connected with splines to the splined shaft 406), which axially (in relation to the main axis of the assigned shaft) move the assigned engagement component 320, through the cam groove 405 and the interaction of the shifting fork protrusion 411 with the cam groove 405. The cam groove 405, guides the provided shifting fork protrusion 411, positioned exemplarily on top of the shifting fork 410.

[0154] As a result due to the formation of the cam groove 405, and due to the interaction of the shifting fork protrusion 411 with the cam groove 405, the engagement component 320 can be pushed (or pulled) to (or from) the assigned divided gear wheel 200, depending on the angular position of the barrel cam 404 (and as a consequence the angular position of the worm wheel 403).

[0155] In addition due to the worm drive (i.e. the worm shaft 402 meshes with the worm wheel 403), when the worm shaft 402 rotates, so does the worm wheel 403. In contrast the rotation of the worm wheel 403 is not permitted by the worm shaft 402. This feature secures the engagement component 320 in place (i.e. engaged or disengaged to the assigned inner part 230), even if there are axial (in relation to the main axis of the shaft) forces, forcing the engagement component 320 to disengage.

[0156] As mentioned before every divided gear wheel 200, has an assigned engagement component 320. As a result and since every engagement component 320 has an assigned shifting fork 410, the number of barrel cams 404, depends on the number of the divided gear wheels 200 selected in the power transmission system. In this depiction only two barrel cams 404 are presented but it is going without saying that more can be adapted. Furthermore preferably, each of the even number of gear ratios (i.e. 2.sup.nd, 4.sup.th, 6.sup.th gear ratio etc.) will share a shaft 406 where the barrel cams 404 are housed and as a result one shifting mechanism 400 will be adapted for the even gear ratios. Consequently one other shifting mechanism 400 will be adapted for the odd number of gear ratios (i.e. 1.sup.st, 3.sup.rd, 5.sup.th gear ratio etc.).

[0157] In addition due the splined shaft 406, the barrel cams 404 are provided as axially movable in relation to the main axis of the shaft 406. This feature is provided as a preventive measure in case the engagement means (teeth) 330 of the engagement component 320, do not “match” the engagement means 231 of the inner part 230 of the divided gear wheel 200. In that case although the engagement component 320 is forced to move towards the assigned inner part 230 of the divided gear wheel 200, this movement cannot take place and the provided springs 408 compress. In order for this compression to take place, the one end of springs 408 is on the face of barrel cams 404 and the other end meets the provided, fixed stop rings 407. Therefore even if the engagement means (teeth) 330 of the engagement component 320, do not “match” the engagement means 231 of the inner part 230 of the divided gear wheel 200, springs 408 will compress up till the “match” between the two is allowed. As a person skilled in the art understands when the presented shifting mechanism 400 is adapted, the engagement means 330 are lengthened.

[0158] In FIG. 11 a detail schematic illustration of the engagement between the inner part 230 of the divided gear wheel 200 and the engagement component 320 can be seen. In this demonstration, an exemplary engagement means (teeth) 330 formation can be seen. The engagement means (teeth) 330 of the engagement component 320, are shaped with slightly angled side surfaces resulting in additional axial force that assists with the disengagement of the engaging components. Due to the formation of the sides of the engagement means (teeth) 330 and the corresponding formation of the engagement means 231 of the inner part 230 of the divided gear wheel 200, an axial force (in relation to the shaft) is applied to the engagement component 320, forcing the engagement component 320, away from the assigned inner part 230, assisting with the disengagement.

[0159] As can be seen the engagement means (teeth) 330 are shaped with an 1° negative angle in both sides of the engagement means (teeth). Due to the negative angle the base of the engagement means (teeth) 330 are wider in relation to the top of the engagement means (teeth). The 1° angle is selected randomly and it is going without saying that any suitable inclination can be chosen.

[0160] In FIG. 12 an alternative formation of the engagement means (teeth) 330 is presented. The figure is similar to the previously presented FIG. 11. In this alternative the sides of the engagement means (teeth) 330 are again shaped with a slight angle but the difference in comparison to the previously presented FIG. 11 lays on the fact that the chosen angle is positive, in comparison to the negative one.

[0161] As can be seen the sides of engagement means (teeth) 330 are shaped with an 1° positive angle in both sides of the engagement means (teeth). Again the engagement means 231 of the inner part 230 of the divided gear wheel 200 are shaped accordingly. The positive angle results in a narrower base in relation to the wider top of engagement means (teeth) 330.

[0162] The negative angle chosen for the sides of the engagement means (teeth) 330 (and the according formation of the engagement means 231 of the inner part 230 of the divided gear wheel 200) results in easier disengagement due to the axial force (in relation to the shaft) applied to the engagement component 320. In case a negative angle is selected, a shifting mechanism like the one presented in FIG. 10 is preferably applied in order to prevent the disengagement of the components when not desired. In contrast when a positive angle is selected, the prevention of disengagement is granted by the design.

[0163] It is worth mentioning that jackshaft can be adapted when is needed.

[0164] In addition the springs 252, 253, 254, 255 inside the divided gear wheel 200 act as a “channel” transferring force/and or power from the outer part 232 to the inner part 230 (and vice versa), with a corresponding deformation.

[0165] The above described power transmission systems, comprising at least one input shaft and at least one output shaft with at least one divided gear wheel in every gear ratio and at least one shifting mechanism that temporarily and/or instantaneously engages two different gear ratios, a CPU that commands a gear changing action after accessing and processing fed data from according measuring instruments and sensors, and a method for operating said power transmission system, allows for a continuous power transfer to the wheels during upshifting, minimizing shifting time and reducing power losses due to clutch disk friction.

LIST OF REFERENCE SIGNS

[0166] 1 power transmission system [0167] 10 input shaft [0168] 20 output shaft [0169] 100 gear wheel [0170] 115 gear tooth [0171] 200 divided gear wheel [0172] 215 divided gear wheel tooth [0173] 221 shaft bearings [0174] 222 inner part bearings [0175] 230 inner part [0176] 231 engagement means of inner part [0177] 232 outer part [0178] 233 outer part elastic element (spring) support [0179] 234 inner part elastic element (spring) support [0180] 241 inner part engaging surfaces [0181] 250 elastic element (spring element) [0182] 252 elastic element (spring element) [0183] 253 elastic element (spring element) [0184] 254 elastic element (spring element) [0185] 255 elastic element (spring element) [0186] 300 dog clutch [0187] 310 dog clutch hub [0188] 320 engagement component [0189] 321 shifting fork groove [0190] 330 engagement means (teeth) [0191] 340 engaging surfaces [0192] 350 guiding means [0193] 360 engagement component engagement means [0194] 371 bushing portion [0195] 380 engagement component arms [0196] 400 shifting mechanism [0197] 401 step motor [0198] 402 worm shaft [0199] 403 worm wheel [0200] 404 barrel cam [0201] 405 cam groove [0202] 406 splined shaft for barrel cams [0203] 407 stop ring [0204] 408 barrel cam springs [0205] 410 shifting fork [0206] 411 shifting fork protrusion