Gearbox

Abstract

The invention is a gearbox that uses the principle of dual-clutch transmissions, but in a highly simplified version that allows for a very large number of gear ratios and eliminates the need for a clutch to change gears. The principle is to alternate the transmission between two elementary transmissions with each rotation of their cycle. This allows for a slight change in the gear ratio of the transmission that does not transmit torque, referred to here as the passive transmission, as opposed to the one that transmits torque, which is called the active transmission. The applications are all those of gearboxes. Abstract figure: Fig. 1

Description

Title of the invention: Gearbox technical field

[0001] The invention is a gearbox. Previous technique

[0002] We know of many documents describing gearboxes, but none resembles the one described below.

[0003] In particular, dual-clutch transmissions are known, which comprise two elementary transmissions, one of which is disengaged while the transmission ratio of the other is changed, but which differ from that according to the present invention in that the transmission of motion into or out of an elementary transmission is done by means of a clutch. Technical problem

[0004] The objective pursued by the present invention is to have, with a very simple and lightweight device, a large number of transmission ratios close to each other, and to avoid having to disengage the transmission at the time of changing the transmission ratio. Brief description of the drawings

[0005] The invention will be well understood, and other objects, advantages and features thereof will become more apparent from the reading of the description which follows, which is illustrated by figures 1 to 4.

[0006] [Fig-1] is a perspective view of a transmission according to the invention, composed of two elementary transmissions, one of which is said to be active because it is connected to the secondary tree 50, and the other is said to be passive because it is disconnected from this secondary tree 50.

[0007] [Fig.2] is a perspective view of the same transmission, the transmission of which was active became passive and vice versa.

[0008] [Fig.3] is a perspective view of one of the elementary transmissions, linking the shaft 10 by a belt or chain 21 to a pinion 22 which supports a rotating arm 23 which drives in rotation a tooth 20. The means of making this tooth circular with center located on the axis of rotation of the intermediate shaft 22 are not represented because there are very many ways of obtaining this circular deformation of a tooth.

[0009] [Fig.4] is a perspective view of the other elementary transmission, which allows see how the rotating arm 33 slides in the intermediate shaft 32, a tooth located at the bottom of this rotating arm cooperating with the teeth of the rotating arm 33 so that only certain positions of this arm are retained when the latter is driven in rotation. Description of the invention

[0010] The invention is a gearbox comprising: - a primary shaft (10) and a secondary shaft (50) comprising a gear set (51), - two transmissions with variable transmission ratios, hereinafter referred to as elementary transmissions, one being said to be active when it ensures the mechanical transmission of the movement from the driving shaft to the driven shaft, and the other being said to be passive otherwise, These two transmissions being put into service alternately, one of said elementary transmissions being able to change its transmission ratio when it is passive, - said elementary transmission, which is passive and capable of changing its transmission ratio on command from an operator or a computer, characterized in that - each of said elementary transmissions includes a so-called secondary gear set (20 for one of the elementary transmissions and 30 for the other) which can cooperate with the gear set (51) of said secondary shaft, - the secondary teeth (20 or 30) of the elementary transmission, which is passive, are separated from the teeth (51) of the shaft (50) before its transmission ratio is modified, - an elementary transmission is provided with a means called a synchronization means such that, following the modification of the transmission ratio of said elementary transmission which is passive, its secondary teeth (20 or 30) are synchronous with the teeth (51) of the secondary shaft (50), said synchronization means having the effect of shifting one or the other of the teeth of said passive transmission by an integer number of teeth, - the secondary teeth (20 or 30) of the elementary transmission which is passive and which has been moved away from the teeth (51) of the shaft (50) is brought closer to said teeth (51) of the shaft (50) when it becomes active again. Detailed description of the invention

[0011] The principle of the present invention is close to that implemented by gearboxes known as "dual-clutch gearboxes", but aims to simplify them and reduce their weight and cost, while allowing a considerable increase in the number of possible transmission ratios.

[0012] The transmission is reversible, the primary shaft and the secondary shaft can both be driving when the other is driven, or driven when the other is driving, and each can include a toothing.

[0013] It comprises two variable transmission ratio transmissions called elementary transmissions, one being said to be active when it ensures the mechanical transmission of the movement from the driving shaft to the driven shaft, and the other being said to be passive in the opposite case.

[0014] These two transmissions are operated alternately, one of the elementary transmissions being able to change its transmission ratio when it is passive, that is, when no force is transmitted by it from the driving shaft to the driven shaft. It can then change its transmission ratio on command from an operator or a computer,

[0015] The originality of the present invention is multifaceted: 1- Each of the said elementary transmissions comprises a secondary gear set that can cooperate with the gear set of the secondary shaft, and optionally a primary gear set that can cooperate with the gear set of the primary shaft 2- The secondary gear of the elementary transmission, which is passive, is separated from the gears of the secondary shaft when it is active, before its transmission ratio is modified. 3- the elementary transmission is equipped with a means called a synchronization means such that, at the end of the modification of the transmission ratio of the elementary transmission which is passive, its secondary teeth are synchronous with the teeth of the secondary shaft, the synchronization means having the effect of shifting one or the other of the teeth of said passive transmission by an integer number of teeth, 4- the secondary teeth of the elementary transmission which is passive and which has been moved away from the teeth of the secondary shaft is brought closer to this teeth when it becomes active again.

[0016] Advantageously, one of the elementary transmissions is active only for less than a part of its 180° rotation.

[0017] Advantageously, the alternation between the two elementary transmissions takes place twice per rotation cycle of the assembly they constitute, each of the two elementary transmissions thus being passive for at least part of the cycle.

[0018] Advantageously, a gear is a flexible drive such as a chain or a synchronous belt, driven in rotation around an axis by a rotating arm whose distance between said axis and the point through which it drives said flexible drive is variable.

[0019] Advantageously, an arm includes a mechanical means such as a notch determining the possible positions of said axis of rotation such as said drive flexible is offset by an integer number of teeth when said arm drives said flexible drive considered.

[0020] The invention also includes the method for modifying the transmission ratio of a gearbox according to the invention, consisting of successively carrying out the following operations: - 1 - disengage at least one of the teeth 20 or 30 from the elementary transmission of the teeth 51 of the shaft 50 when it is active so that it becomes passive, - 2 - to change its transmission ratio while it is passive, - 3 - bring the teeth of the elementary transmission 20 or 30 closer to the teeth 51 of the secondary shaft 50. Applications

[0021] The applications of the present invention are all those of gearboxes.

Claims

Demands

1. Gearbox comprising: - a primary shaft (10) and a secondary shaft (50) including teeth (51), - two transmissions with variable gear ratios, hereinafter referred to as elementary transmissions, one being said to be active when it ensures the mechanical transmission of the movement from the driving shaft to the driven shaft, and the other being said to be passive otherwise, these two transmissions being put into service alternately, one of said elementary transmissions being able to change its gear ratio when it is passive, - said elementary transmission which is passive being able to change its gear ratio on the command of an operator or a computer, characterized in that - each of said elementary transmissions includes a set of teeth called secondary (20 for one of the elementary transmissions and 30 for the other) being able to cooperate with the teeth (51) of said secondary shaft,- the secondary teeth (20 or 30) of the passive elementary transmission are moved away from the teeth (51) of the shaft (50) before its transmission ratio is modified; - an elementary transmission is equipped with a means called a synchronization means such that, after the modification of the transmission ratio of said passive elementary transmission, its secondary teeth (20 or 30) are synchronous with the teeth (51) of the secondary shaft (50), said synchronization means having the effect of shifting one or the other of the teeth of said passive transmission by an integer number of teeth; - the secondary teeth (20 or 30) of the passive elementary transmission, which have been moved away from the teeth (51) of the shaft (50), are brought closer to said teeth (51) of the shaft (50) when it becomes active again.

2. Gearbox according to claim 1 characterized in that one of said elementary transmissions is active only for less than a part of its 180° rotation.

3. Gearbox according to claim 2 characterized in that the alternation between the two elementary transmissions takes place twice per rotation cycle of the assembly they constitute, each of the two elementary transmissions thus being passive during at least part of the cycle.

4. Gearbox according to any one of the preceding claims characterized in that a toothing is a flexible drive such as a synchronous chain or belt, driven in rotation about an axis by a rotating arm whose distance between said axis and the point through which it drives said flexible drive is variable.

5. Gearbox according to claim 4 characterized in that said arm comprises a mechanical means such as a notch determining the possible positions of said axis of rotation such that said flexible drive is offset by an integer number of teeth when said arm drives said flexible drive considered.

6. A method for modifying the transmission ratio of a gearbox comprising - a primary shaft (10) and a secondary shaft (50) including teeth (51), - two transmissions with variable transmission ratios, hereinafter referred to as elementary transmissions, one being said to be active when it ensures the mechanical transmission of the motion from the driving shaft to the driven shaft, and the other being said to be passive otherwise, these two transmissions being put into operation alternately, one of said elementary transmissions being able to change its transmission ratio when it is passive, each of said elementary transmissions including a set of teeth called secondary (20 or 30) being able to cooperate with the teeth (51) of said secondary shaft (50), one elementary transmission being provided with a means called a synchronization means such that, following the modification of the transmission ratio of said elementary transmission which is passive,its secondary teeth (20 or 30) be synchronous with the teeth (51) of the secondary shaft (50), said synchronization means having the effect of shifting one or the other of the teeth of said passive transmission by an integer number of teeth, characterized in that said modification of the transmission ratio consists of successively carrying out the following operations: - 1 - disengage at least one of the transmission teeth elementary which is passive of the teeth (51) of the tree (50) - 2 - modify its transmission ratio, - 3 - bring the teeth of the elementary transmission which has been moved away from the teeth (51) of the shaft (50).

Images