FR2822914A1 - Vehicle gearbox comprises primary and secondary shafts with pinions on each shaft which mesh with each other selectively to obtain transmission ratio - Google Patents

Abstract

The gearbox comprises a primary shaft (10) receiving the engine power and a secondary shaft (20) transmitting the power. There are a series of components on the two shafts, a first pinion (1) on the primary shaft and a second component (2) comprising two pinions (2A,2B) on the secondary shaft, the first of which meshes with the primary shaft pinion. There are two following components (3,4,5') comprising two pinions, the first of which meshes with the second pinion of the second component. The last component (5) comprises a pinion meshing with the second pinion (4D) of the previous component (4). Couplings (11,21,22) selectively couple each component to the shaft which carries it. A transmission ratio is obtained by coupling a component on the primary shaft and a component on the secondary shaft.

Description

<Desc / Clms Page number 1>

Transmission for vehicle.

 The invention relates to a gearbox for a vehicle.

 In a conventional manual gearbox, a primary shaft and a secondary shaft are connected in parallel and carry pairs of gears, the first gear being mounted on the primary shaft, the second gear being mounted on the secondary shaft and meshing with the first pinion to form a gear. One of the pinions is rotatably mounted on the shaft, and coupling means make it possible to link said pinion to the shaft on command. The meshing ratio of the gear then determines the ratio of the rotational speeds of the shafts.

 In general, the gearbox has four or five gears with a pair of gears for as many gears, with a set of three additional gears for a reverse gear. In a neutral position, no rotating pinion is coupled to a shaft.

When a gear is selected, only the rotary gear of the gear concerned is coupled to the shaft that carries it.

 If it is desired to add an additional transmission ratio to provide a six-speed gearbox, an additional gear can be added. However, this increases the axial size of the gearbox, which is not always compatible with the constraints

<Desc / Clms Page number 2>

d'implantation d'un groupe motopropulseur dans le compartiment moteur d'un véhicule.

installing a powertrain in the engine compartment of a vehicle.

 To limit the axial size of the gearbox, the document FR 2 790 052 proposes a pinion gear which has a jaw tooth to cause the pinion to be rotatably connected to the shaft which carries it by a synchronizer. Said idler gear comprises a hub and a crown, the two parts being assembled permanently. This technique makes it possible to overcome manufacturing constraints of the pinion in one piece and thus reduce its axial size. The use of such sprockets does not preclude the use of other techniques to further reduce the axial size of the gearbox.

 FR 2 787 162 discloses a gearbox which comprises a primary shaft and two secondary shafts. The primary shaft carries five fixed gears, the first secondary shaft comprises three idle gears meshing with the primary shaft gears, the second secondary shaft comprises three idle gears meshing with gears of the primary shaft, each secondary shaft having in in addition to a pinion meshing with a pinion carried by an output shaft. So one of the fixed gears meshes with two crazy gears. Each of the six idle gears has coupling means to the shaft which carries it, thus to determine six transmission ratios.

 The gearbox shown in document FR 2787 853 comprises two box parts each with a primary shaft and a clutch. Two

<Desc / Clms Page number 3>

arbres secondaires engrènent avec un même arbre de sortie et portent chacun quatre pignons fous. Les deux arbres primaires sont coaxiaux. Un pignon fou coaxial aux deux arbres primaires engrène avec deux pignons fous portés respectivement par chaque arbre secondaire et peut être couplé de manière sélective à l'un ou l'autre des arbres primaires. On obtient ainsi une boîte à six rapports qui peuvent être passés sous charge.

secondary shafts mesh with the same output shaft and each carry four crazy gears. The two primary trees are coaxial. An idler gear coaxial with the two primary shafts meshes with two idle gears carried respectively by each secondary shaft and can be selectively coupled to one or the other of the primary shafts. This gives a six-speed box that can be passed under load.

 Document FR 2 780 761 shows a gearbox with two secondary shafts and two clutches. The first secondary shaft comprises four idler gears, all integral with each other, with means for coupling the gears to the secondary shaft. The primary shaft carries two sets each comprising a clutch and two integral pinions. This transmission also provides six forward gears and a reverse gear, the forward gears can be passed under load.

 All these gearboxes have the disadvantage of having excessive space requirement either axial or radial because of the presence of two secondary trees.

 It is therefore an object of the invention to provide a gearbox having a large number of forward gears with minimal bulk.

 With this objective in view, the subject of the invention is a gearbox for a vehicle comprising a first shaft and a second shaft, one being a

<Desc / Clms Page number 4>

arbre primaire pour recevoir une puissance d'un moteur, l'autre étant un arbre secondaire pour transmettre la puissance, caractérisée en ce qu'elle comporte en outre une série d'éléments de transmission montés rotatifs sur les arbres, disposés alternativement sur le premier et le deuxième arbre, un premier élément monté sur le premier arbre et comportant un pignon, un deuxième élément monté sur le deuxième arbre et comportant deux pignons solidaires dont le premier engrène avec le pignon du premier élément, des éléments suivants comportant deux pignons solidaires dont le premier engrène avec le deuxième pignon de l'élément précédent, le dernier élément comportant un pignon engrenant avec le deuxième pignon de l'élément précédent, des moyens de couplage permettant de coupler sélectivement chaque élément à l'arbre qui le porte, un rapport de transmission étant obtenu en couplant un élément sur l'arbre primaire et un élément sur l'arbre secondaire.

primary shaft for receiving a power from a motor, the other being a secondary shaft for transmitting power, characterized in that it further comprises a series of transmission elements rotatably mounted on the shafts, arranged alternately on the first and the second shaft, a first element mounted on the first shaft and comprising a pinion, a second element mounted on the second shaft and having two integral pinions, the first meshing with the pinion of the first element, the following elements comprising two solidarity pinions including the first meshes with the second gear of the previous element, the last element comprising a pinion meshing with the second gear of the previous element, coupling means for selectively coupling each element to the shaft which carries it, a ratio transmission being obtained by coupling an element on the primary shaft and an element on the secondary shaft re.

 Thanks to the invention, a compact gearbox is obtained. It only has a secondary shaft. In addition, a greater number of transmission ratios is obtained than the number of pairs of gears. Direct gears ratios comprising a pair of gears are obtained by bonding each member that carries the considered pinion to the shaft that carries it. In addition, by coupling to the shafts non-successive elements, the movement is transmitted from the primary shaft to the secondary shaft through a plurality of transmission elements, thus combining transmission ratios. With the same number

<Desc / Clms Page number 5>

d'engrenages, il est donc possible d'obtenir un plus grand nombre de rapports de transmission. Pour un nombre de rapports de transmission donné, l'encombrement axial de la boîte de vitesses est réduit.

of gears, it is therefore possible to obtain a larger number of transmission ratios. For a given number of transmission ratios, the axial size of the gearbox is reduced.

 The coupling means are for example synchronizers. The control of these synchronizers is performed either conventionally by a manual command, or by a robotic control.

 If the transmission has a series of four elements, there are three direct gear ratios and one additional gear by simultaneously coupling the first and fourth gear on their respective shafts - a total of four gears.

We thus obtain a very compact four-speed gearbox.

 In a first embodiment, the gearbox comprises a series of five elements to obtain an arrangement in three transmission ratio pairs, a predetermined opening existing between the elements of each pair of transmission ratios taken in the arrangement.

 Conventionally, the opening between two transmission ratios is defined as being the result of the division of the two transmission ratios.

The opening is chosen greater than one in the increasing order of the speeds of the box.

 Thus, the gearbox has four gears of pairs of gears. The box thus makes it possible to obtain four first transmission ratios

<Desc / Clms Page number 6>

directs déterminés par le rapport des nombres de dents d'engrenages. De plus, en couplant le premier élément sur le premier arbre et le quatrième élément sur le deuxième arbre, on obtient un cinquième rapport de transmission. De même, en couplant le deuxième élément sur le deuxième arbre et le cinquième élément sur le premier arbre, on obtient un sixième rapport de transmission. La boîte de vitesses a ainsi six rapports de transmission avec seulement quatre engrenages et un seul arbre secondaire.

direct determined by the ratio of the number of gear teeth. In addition, by coupling the first element on the first shaft and the fourth element on the second shaft, a fifth transmission ratio is obtained. Likewise, by coupling the second element on the second shaft and the fifth element on the first shaft, a sixth transmission ratio is obtained. The gearbox thus has six gear ratios with only four gears and a single secondary shaft.

 The fifth and sixth transmission ratios are determined by the other transmission ratios. As will be explained later, it is found that the opening between the second and the third ratio is equal to that between the first and the sixth report and that between the fifth and the fourth report.

 Preferably, the transmission ratios of the first pair of the arrangement are assigned respectively to the first and the second speed, the transmission ratios of the second pair of the arrangement are assigned respectively to the third and the fifth speed, the transmission ratios of the third pair of the arrangement are assigned respectively to the fourth and the sixth speed.

 This choice of combinations allows a good staging speeds. Indeed, we obtain a significant opening between the first and the second speed, and a smaller opening between the third, the fourth, the fifth and the sixth speed, when it is desirable to make

<Desc / Clms Page number 7>

fonctionner le moteur dans une plage restreinte de fonctionnement optimisé.

operate the motor within a restricted range of optimized operation.

 In a second embodiment, the gearbox comprises a series of six elements.

- deuxième élément et cinquième élément - troisième et sixième élément. Thus, the gearbox has five gears and thus provides five first direct transmission ratios determined by the ratio of the number of teeth of each gear. In addition, four additional transmission ratios can be obtained by coupling with the shafts of the following elements: first element and fourth element first element and sixth element;

- second element and fifth element - third and sixth element.

 Thus, the gearbox makes it possible to obtain nine different transmission ratios. They are not necessarily all used and, in this case, only those which allow to obtain an interesting staging of the reports are ordered.

la deuxième vitesse par le premier et le quatrième élément ; la troisième vitesse par le deuxième et le troisième élément ; According to a first variant, the speed ratios are obtained by coupling with the shafts of the following elements: the first speed by the first and the second element;

the second gear by the first and the fourth element; the third gear by the second and the third element;

<Desc / Clms Page number 8>

la quatrième vitesse par le deuxième et le cinquième élément ; la cinquième vitesse par le troisième et le quatrième élément ; la sixième vitesse par le cinquième et le sixième élément ; la septième vitesse par le quatrième et le cinquième élément.

the fourth gear by the second and the fifth element; the fifth gear by the third and the fourth element; the sixth speed by the fifth and the sixth element; the seventh gear by the fourth and the fifth element.

 According to a second variant, the speed ratios are obtained by coupling with the shafts of the following elements: the first speed by the second and the third element; the second gear by the second and the fifth element; the third gear by the third and the fourth element; the fourth speed by the third and the sixth element; the fifth gear by the fourth and the fifth element; the sixth speed by the first and the second element; the seventh gear by the fifth and the sixth element.

 For both variants, the primary shaft may be the first shaft and the secondary shaft the second shaft, or vice versa.

<Desc / Clms Page number 9>

En augmentant le nombre d'éléments, on multiplie très rapidement le nombre de rapports disponibles, soit tous utilisables, soit utilisés de manière sélective pour optimiser l'étagement des rapports.

By increasing the number of elements, one multiplies very quickly the number of available reports, either all usable, or used selectively to optimize the staging of the reports.

 The invention will be better understood and other features and advantages will become apparent on reading the description which follows, the description referring to the appended drawings in which: FIG. 1 is a sectional view of a gearbox according to a first embodiment of the invention; Figure 2 is a schematic view of the gearbox according to the first embodiment, in a neutral position; Figures 3 to 8 are schematic views similar to Figure 2, with the various reports engaged; Figure 9 is a schematic view of a gearbox according to a second embodiment of the invention; Figures 10 and 11 are schematic views similar to Figure 9, with different gear engaged.

 The gearbox according to a first embodiment of the invention, shown in Figure 1, comprises a housing 30, a primary shaft 10 rotatably mounted in the housing by means of bearings 40 and a secondary shaft 20 also rotatably mounted. in the crankcase via

<Desc / Clms Page number 10>

roulements 40. L'arbre primaire 10 reçoit le mouvement d'un moteur non montré. L'arbre secondaire 20 transmet le mouvement à la couronne d'un différentiel, non montré, par le pignon de différentiel 24.

Bearings 40. The primary shaft 10 receives the movement of an engine not shown. The secondary shaft 20 transmits the movement to the crown of a differential, not shown, by the differential gear 24.

 Transmission elements are rotatably mounted on the shafts. A first element 1 is carried by the secondary shaft 20 and comprises a pinion. A second element 2 is carried by the primary shaft 10 and comprises a first pinion 2A meshing with the pinion of the first element 1 to form a first gear A, and a second pinion 2B. A third element 3 is carried by the secondary shaft 20 and comprises a first gear 3B meshing with the second gear 2B of the second element 2 to form a second gear B, and a second pinion 3C. A fourth element 4 is carried by the primary shaft 10 and comprises a first pinion 4C meshing with the second pinion 3C of the third element 3 to form a third gear C, and a second pinion 4D. A fifth element 5 is carried by the secondary shaft 20 and has a toothing meshing with the second pinion 4D of the fourth element 4 to form a fourth gear D.

 The secondary shaft 20 comprises a first synchronizer 21 between the first 1 and the third element 3. In a conventional manner, the first synchronizer 21 comprises a flange 213 fixed on the shaft 20, a sliding device 211 two elastic rings 212, 214, for selectively coupling the first 1 or the third 3 element to the secondary shaft 20 or do not couple any of the two elements 1.3. Similarly,

<Desc / Clms Page number 11>

l'arbre primaire 10 comporte un deuxième synchroniseur 11 entre le deuxième 2 et le quatrième élément 4 pour coupler sélectivement lesdits éléments 2,4 à l'arbre primaire 10.

the primary shaft 10 comprises a second synchronizer 11 between the second 2 and the fourth element 4 for selectively coupling said elements 2.4 to the primary shaft 10.

 A third synchronizer 22 is fixed on the secondary shaft next to the fifth element 5 to couple on command said element 5 to the shaft 20.

 Figures 2 to 8 show schematically the gearbox according to the first embodiment. Figure 2 shows a neutral position in which no element is coupled to the shafts by the synchronizers. There is therefore no connection to transmit a movement between the two trees 10,20.

 In a conventional manner, the transmission ratio is the rotational speed of the secondary shaft divided by that of the primary shaft.

In the case of a gear comprising a pair of pinions, it is determined by the number of teeth of the pinion on the primary shaft divided by the number of teeth of the pinion carried by the secondary shaft.

 In FIG. 3, the first synchronizer 21 is shown connected to the first element 1 to symbolize that the first element 1 is coupled to the secondary shaft 20. Similarly, the second synchronizer 11 is shown adjacent to the second element 2 to symbolize that the second element 2 is coupled to the primary shaft 10. Thus, the shafts 10,20 are linked by the first gear A with a ratio RA of transmission determined by the number of teeth of the pinions of the gear A. The elements 1, 2

<Desc / Clms Page number 12>

impliqués dans la transmission sont représentés en traits larges.

involved in the transmission are represented in broad lines.

 Likewise, as shown in FIG. 4, a transmission ratio RB is obtained by coupling the second element 2 on the primary shaft 10 via the second synchronizer 11 and the third element 3 on the secondary shaft 20 by the intermediate of the first synchronizer 21. The transmission ratio RB is determined by the number of teeth of the gears of the second gear B.

 Likewise, as shown in FIG. 5, a transmission ratio RC is obtained by coupling the fourth element 4 on the primary shaft 10 via the second synchronizer 11 and the third element 3 on the secondary shaft 20 by the intermediate of the first synchronizer 21. The transmission ratio RC is determined by the number of teeth of the gears of the third gear C.

 Similarly, as shown in FIG. 6, a transmission ratio RD is obtained by coupling the fourth element 4 on the primary shaft 10 via the second synchronizer 11 and the fifth element 5 on the secondary shaft 20 by the 3. The transmission ratio RD is determined by the number of teeth of the gears of the fourth gear D.

 As shown in FIG. 7, a first additional ratio R1 is obtained by coupling the second element 2 on the primary shaft 10 via the second synchronizer 11 and the fifth element 5 on the secondary shaft 20 via the

<Desc / Clms Page number 13>

troisième synchroniseur 22. Les trois engrenages B, C et D interviennent dans la transmission du mouvement entre l'arbre primaire et l'arbre secondaire 20, le rapport RI de transmission étant déterminé par une combinaison des rapports RB, RC et RD, avec la relation suivante :

third synchronizer 22. The three gears B, C and D intervene in the transmission of motion between the primary shaft and the secondary shaft 20, the transmission ratio RI being determined by a combination of ratios RB, RC and RD, with the following relation:

As shown in FIG. 8, a second additional ratio R2 is obtained by coupling the fourth element 4 on the primary shaft 10 via the second synchronizer 11 and the first element 1 on the secondary shaft 20 via the first synchronizer 21. The three gears A, B and C intervene in the transmission of motion between the primary shaft 10 and the secondary shaft 20, the transmission ratio R2 being determined by a combination of RA, RB and RC ratios, with the following relation:

If we note N followed by the reference of a pinion the number of teeth of said pinion, the transmission ratios are expressed by the relations:

Relations defining RI and R2, we deduce the following equalities:

<Desc / Clms Page number 14>

La constante X détermine une ouverture entre les éléments d'un couple de rapports de transmission défini par les fractions membres des égalités.

The constant X determines an opening between the elements of a pair of transmission ratios defined by the fractions members of equalities.

 To build a gearbox according to the invention, the designer has the choice to determine with which transmission ratios we obtain the speeds, from the first to the sixth. Indeed, there are several different arrangements for assigning speeds to transmission ratios.

 A first step of this choice is to determine between which speeds will the opening X.

Of all the possible combinations, only three combinations are realistic (opening greater than one between the successive speeds). If we denote Di the transmission ratio of the ith speed, the previous equalities can be expressed for the three combinations in the following way:

<Tb>
<tb><SEP> Relations Between <SEP><SEP> Reports
<tb> of <SEP><SEP> transmission of <SEP> speeds
<tb> First <SEP> combination <SEP> D2 <SEP> = <SEP> D4 <SEP> = <SEP> D6 <SEP> = <SEP> X
<tb> D1 <SEP> D3 <SEP> D5
<tb> Second <SEP> combination <SEP> D2 <SEP> = <SEP> D5 <SEP> = <SEP> D6 <SEP> = <SEP> X
<tb> D1 <SEP> D3 <SEP> D4
<tb> Third <SEP> combination <SEP> D4 <SEP> = <SEP> D5 <SEP> = <SEP> D6 <SEP> = <SEP> X
<tb> Dl <SEP> D2 <SEP> D3
<Tb>

The first and the third combination make it possible to obtain constant openings between the successive speeds.

 According to the second combination, given as

<Desc / Clms Page number 15>

for example, the speeds are affected in the following way:

<Tb>
<tb> Speed <SEP> Report <SEP> of <SEP> Linked <SEP> Sprocket <SEP> Linked <SEP> Sprocket
<tb> transmission <SEP> to <SEP> tree <SEP> to <SEP> tree
<tb> primary <SEP> secondary
<tb> First <SEP> R2 <SEP> 0, <SEP> 1704 <SEP> 4 <SEP> 1
<tb> Second <SEP> RA <SEP> 18/47 <SEP> 2 <SEP> 1
<tb> Third <SEP> RC <SEP> 19/33 <SEP> 4 <SEP> 3
<tb> Fourth <SEP> RD <SEP> 19/22 <SEP> 4 <SEP> 5
<tb> Fifth <SEP> RB <SEP> 22/17 <SEP> 2 <SEP> 3
<tb> Sixth <SEP> RI <SEP> 1, <SEP> 9455 <SEP> 2 <SEP> 5
<Tb>

In this example, the opening between the first speed and the second is 2.25, and 1.5 between the following speeds. Such a gearbox corresponds to a current five-speed gearbox to which a sixth overdrive gear would have been added.

 In a second embodiment, shown in FIG. 9, a gearbox according to the invention comprises, as in the first embodiment, the primary shaft 10, the secondary shaft 20 and the first four elements 1 to 4.

 A fifth element 5 is carried by the secondary shaft 20 and comprises a first pinion 5D meshing with the second pinion 4D of the fourth element 4 to form the fourth gear D, and a second pinion 5E. A sixth element 6 is carried by the primary shaft 10 and comprises a pinion meshing with the second pinion 5E of the fifth element 5 'to form a fifth gear E. A

<Desc / Clms Page number 16>

quatrième synchroniseur 12 permet de coupler de manière sélective le sixième élément 6 à l'arbre primaire 10.

fourth synchronizer 12 makes it possible to selectively couple the sixth element 6 to the primary shaft 10.

 As in the first embodiment, five direct transmission ratios are obtained, the fifth transmission ratio RE being obtained by coupling the fifth element 5 'with the secondary shaft 20 and the sixth element 6 with the primary shaft 10 via the synchronizer 12. The first two additional ratios R1 and R2 are also obtained.

A third additional report R3 is obtained by coupling the sixth element 6 on the primary shaft 10 via the fourth synchronizer 12 and the third element 3 on the secondary shaft 20 via the first synchronizer 21, as shown on FIG. 10. The three gears C, D and E intervene in the transmission of the movement between the primary shaft and the secondary shaft 20, the transmission ratio R3 being determined by a combination of the ratios RC, RD and RE, with the following relation:

A fourth additional report R4 is obtained by coupling the sixth element 6 on the primary shaft 10 via the fourth synchronizer 12 and the first element 1 on the secondary shaft 20 via the first synchronizer 21, as shown on Figure 11. The five gears A, B, C, D and E are involved in the

<Desc / Clms Page number 17>

transmission du mouvement entre l'arbre primaire 10 et l'arbre secondaire 20, le rapport R4 de transmission étant déterminé par une combinaison des rapports RA, RB, RC, RD et RE avec la relation suivante :

transmission of motion between the primary shaft 10 and the secondary shaft 20, the transmission ratio R4 being determined by a combination of the ratios RA, RB, RC, RD and RE with the following relation:

All transmission reports are not necessarily used. In the examples that follow, only seven transmission ratios are used.

According to a first variant, given by way of example, the speeds are affected as follows:

<Tb>
<tb> Speed <SEP> Report <SEP> of <SEP> Linked <SEP> Sprocket <SEP> Linked <SEP> Sprocket
<tb> transmission <SEP> to <SEP> tree <SEP> to <SEP> tree
<tb> primary <SEP> secondary
<tb> First <SEP> RA <SEP> 11/43 <SEP> 2 <SEP> 1
<tb> Second <SEP> R2 <SEP> 0, <SEP> 4693 <SEP> 4 <SEP> 1
<tb> Third <SEP> RB <SEP> 31/43 <SEP> 2 <SEP> 3
<tb> Fourth <SEP> RI <SEP> 1, <SEP> 00825 '
<tb> Fifth <SEP> RC <SEP> 41/31 <SEP> 4 <SEP> 3
<tb> Sixth <SEP> RE <SEP> 47/30 <SEP> 6 <SEP> 5 '
<tb> Seventh <SEP> RD <SEP> 37/20 <SEP> 4 <SEP> 5 '
<tb> Report <SEP> no <SEP> R3 <SEP> 1,120 <SEP> 6 <SEP> 3
<tb> used
<tb> Report <SEP> no <SEP> R4 <SEP> 0.397 <SEP> 6 <SEP> 1
<tb> used
<Tb>

According to a second variant, given by way of example, the speeds are affected in the manner

<Desc / Clms Page number 18>

next :

<Tb>
<tb> Speed <SEP> Report <SEP> of <SEP> Linked <SEP> Sprocket <SEP> Linked <SEP> Sprocket
<tb> transmission <SEP> to <SEP> tree <SEP> to <SEP> tree
<tb> primary <SEP> secondary
<tb> First <SEP> RE <SEP> 11/43 <SEP> 6 <SEP> 5 '
<tb> Second <SEP> R3 <SEP> 0, <SEP> 4693 <SEP> 2 <SEP> 5 '
<tb> Third <SEP> RD <SEP> 31/4345 '
<tb> Fourth <SEP> R1 <SEP> 1, <SEP> 008 <SEP> 6 <SEP> 3
<tb> Fifth <SEP> RC <SEP> 41/3143
<tb> Sixth <SEP> RA <SEP> 47/30 <SEP> 2 <SEP> 1
<tb> Seventh <SEP> RB <SEP> 37/2023
<tb> Report <SEP> no <SEP> R2 <SEP> 1,120 <SEP> 4 <SEP> 1
<tb> used
<tb> Report <SEP> no <SEP> R4 <SEP> 0.397 <SEP> 6 <SEP> 1
<tb> used
<Tb>

This second variant has a provision equivalent to the first variant, with a reversal of the primary and secondary shafts.

 According to a third variant, given by way of example, the speeds are affected as follows:

<Desc / Clms Page number 19>

<Tb>
<tb> Speed <SEP> Report <SEP> of <SEP> Linked <SEP> Sprocket <SEP> Linked <SEP> Sprocket
<tb> transmission <SEP> to <SEP> tree <SEP> to <SEP> tree
<tb> primary <SEP> secondary
<tb> First <SEP> RB <SEP> 11/43 <SEP> 2 <SEP> 3
<tb> Second <SEP> RI <SEP> 0, <SEP> 4693 <SEP> 2 <SEP> 5 '
<tb> Third <SEP> RC <SEP> 31/43 <SEP> 4 <SEP> 3
<tb> Fourth <SEP> R3 <SEP> 1, <SEP> 008 <SEP> 6 <SEP> 3
<tb> Fifth <SEP> RD <SEP> 41/31 <SEP> 4 <SEP> 5 '
<tb> Sixth <SEP> RA <SEP> 47/30 <SEP> 2 <SEP> 1
<tb> Seventh <SEP> RE <SEP> 37/20 <SEP> 6 <SEP> 5 '
<tb> Report <SEP> no <SEP> R2 <SEP> 4,4151 <SEP> 4 <SEP> 1
<tb> used
<tb> Report <SEP> no <SEP> R4 <SEP> 6,175 <SEP> 6 <SEP> 1
<tb> used
<Tb>

According to a fourth variant, given by way of example, the speeds are affected as follows:

<Tb>
<tb> Speed <SEP> Report <SEP> of <SEP> Linked <SEP> Sprocket <SEP> Linked <SEP> Sprocket
<tb> transmission <SEP> to <SEP> tree <SEP> to <SEP> tree
<tb> primary <SEP> secondary
<tb> First <SEP> RD <SEP> 11/43 <SEP> 4 <SEP> 5 '
<tb> Second <SEP> R1 <SEP> 0.4693 <SEP> 2 <SEP> 5 '
<tb> Third <SEP> 31/43 <SEP> 4 <SEP> 3
<tb> Fourth <SEP> R3 <SEP> 1,008 <SEP> 6 <SEP> 3
<tb> Fifth <SEP> 3
<tb> Sixth <SEP> RE <SEP> 47/3065 '
<tb> Seventh <SEP> RA <SEP> 37/20 <SEP> 2 <SEP> 1
<tb> Report <SEP> No <SEP> R2 <SEP> 1,008 <SEP> 4 <SEP> 1
<tb> used
<tb> Report <SEP> no <SEP> R4 <SEP> 6,176 <SEP> 6 <SEP> 1
<tb> used
<Tb>

<Desc / Clms Page number 20>

Cette quatrième variante a une disposition équivalente à la troisième variante, avec une inversion des arbres primaire et secondaire.

This fourth variant has a provision equivalent to the third variant, with a reversal of the primary and secondary shafts.

In the four variants, the openings between the successive speeds are as follows:

<Tb>
<tb> Between <SEP> And <SEP> Opening
<tb> First <SEP> Second <SEP> 1, <SEP> 8335
<tb> Second <SEP> Third <SEP> 1.5362
<tb> Third <SEP> Fourth <SEP> 1, <SEP> 3988
<tb> Fourth <SEP> Fifth <SEP> 1,3115
<tb> Fifth <SEP> Sixth <SEP> 1.1846
<tb> Sixth <SEP> Seventh <SEP> 1,1809
<Tb>

The invention is not limited to the embodiments which have been described solely by way of example. A gearbox according to the invention will also include a reverse gear. It may include an even larger number of transmission elements.

Claims (6)

 A vehicle gearbox having a first shaft and a second shaft, one being a primary shaft (10) for receiving power from one engine, the other being a secondary shaft (20) for transmitting power, characterized in that it further comprises a series of rotatably mounted transmission elements on the shafts, arranged alternately on the first (20) and the second shaft (20), a first element (1) mounted on the first shaft ( 20) and comprising a pinion, a second element (2) mounted on the second shaft (10) and having two integral pinions (2A, 2B), the first (2A) meshes with the pinion of the first element (1), elements following (3,4,5 ') having two integral pinions, the first meshes with the second pinion of the previous element, the last element (5,6) comprising a pinion meshing with the second pinion (4D, 5E) of the previous element (4, 51), coupling means (11, 12, 21) , 22) for selectively coupling each element to the shaft which carries it, a transmission ratio being obtained by coupling an element (2, 4,6) on the primary shaft (10) and an element (1,3, 5, 5 ') on the secondary shaft (20).  2. Transmission according to claim 1, characterized in that it comprises a series of five elements (1,2, 3,4, 5) to obtain an arrangement in three transmission ratio pairs (RB, RC; RA , R2, R1, RD), a predetermined opening (X) existing between the elements of <Desc / Clms Page number 22>  each pair of transmission ratios taken in the arrangement.

 Gearbox according to Claim 2, characterized in that the transmission ratios of the first pair of the arrangement are assigned respectively to the first and second speeds, the transmission ratios of the second pair of the arrangement are allocated. at the third and fifth speeds, respectively, the transmission ratios of the third pair of the arrangement are assigned to the fourth and sixth speeds respectively.  4. Gearbox according to claim 1, characterized in that it comprises a series of six elements (1,2, 3,4, 5 ', 6).  5. Gearbox according to claim 4, characterized in that the gear ratios are obtained by coupling with the shafts of the following elements: the first gear by the first (1) and the second element (2);

 the second speed by the first (1) and the fourth element (4); the third speed by the second (2) and the third element (3); the fourth speed by the second (2) and the fifth element (5 '); the fifth speed by the third (3) and the fourth element (4); the sixth gear by the fifth (5 ') and the <Desc / Clms Page number 23>  sixth element (6); the seventh speed by the fourth (4) and the fifth element (5 ').

 Gearbox according to Claim 4, characterized in that the gear ratios are obtained by coupling with the shafts of the following elements: the first gear by the second (2) and the third gear (3); the second speed by the second (2) and the fifth element (5 '); the third speed by the third (3) and the fourth element (4); the fourth speed by the third (3) and the sixth element (6); the fifth speed by the fourth (4) and the fifth element (5 '); the sixth speed by the first (1) and the second element (2); the seventh speed by the fifth (5 ') and the sixth element (6).