WO1998038444A1

WO1998038444A1 - Booster device for gear box

Info

Publication number: WO1998038444A1
Application number: PCT/FR1998/000398
Authority: WO
Inventors: Dominique Crasset
Original assignee: Ace Engineering S.A.
Priority date: 1997-02-28
Filing date: 1998-03-02
Publication date: 1998-09-03
Also published as: FR2760263A1; FR2760263B1

Abstract

The invention concerns a gear box booster device in which a barrel (5) controls the displacement of a shift fork (2), comprising an actuator (11) arranged, in a first phase of gear shifting from dead centre, to be positioned by rotation of the barrel for sensing the direction of the displacement of the shifting fork, and in a second phase of said gearshift, to boost the movement required by the barrel upstream of the latter.

Description

ASSISTANCE DEVICE FOR GEARBOX

The present invention relates to an assistance device for a gearbox, and more particularly for a barrel-controlled gearbox.

Such gearboxes are well known, and are used in particular on motorcycles, where the barrel is integrated into the gearbox itself, of which it directly controls the forks. Document WO-A-96/23995 also describes a gearbox control by barrel, but the latter is outside the box and controls it via a linkage and levers.

The aforementioned document also provides assistance between the gear lever and the barrel, that is to say upstream of the latter. This assistance therefore has the effect of facilitating the rotary drive of the barrel by the user.

Such an arrangement generally gives satisfaction. However, the tracks of the barrel which act like cams offer with the pawn which circulates in them a linear contact. This contact is the site of high mechanical stresses, in particular during engagement of the gears, and very particularly when the rotation of the barrel is assisted. In some cases, these constraints prohibit sufficient wear over time.

The present invention aims to overcome these drawbacks. To this end, the subject of the invention is an assistance device for a gearbox in which a barrel controls the movement of a fork, characterized in that it comprises an actuator arranged for, in a first phase of passage from a speed from neutral, be set by the rotation of the barrel in a position for detecting the direction of movement of the fork, and in a second phase of the passage of said speed, assist a movement requested by the barrel downstream of the last.

It is therefore no longer a question here, as in the prior art, of assisting the rotation of the barrel, which leads to increasing the stresses on the track and the follower pin. On the contrary, assistance intervenes in the invention downstream of the barrel, to assist the gear change movement commanded by the latter and thus relieve the forces transmitted from the track to the follower pin. Ultimately, the barrel could be considered only as the control of the actuator, the latter taking over almost all of the efforts necessary for the gear shift movement.

Furthermore, and according to another aspect of the invention, the passage of a gear from the neutral point is carried out according to the invention in two phases. The assistance does not intervene during the first phase, during which the actuator only positions itself according to the direction of rotation of the barrel. It is only during the second phase, during the engagement of the speed where the efforts are the highest, that the assistance intervenes.

In a particular embodiment of the invention, said actuator is a hydraulic cylinder. More particularly, said cylinder may comprise, between its casing and a distributor drawer, a rotating jacket whose rotation is controlled by the control of the barrel.

Also in a particular embodiment, the control of the barrel is a sequential control, for example of the type described in the aforementioned document.

The jacket can in this case be rotated by a pawl control barrel holder.

A track follower pin can be mounted integral with a gear shift fork, said actuator being arranged to assist the movement of said pin and said fork.

In the case of an actuator constituted by a hydraulic cylinder, the pin and the fork can then be integral with the rod of said cylinder.

A particular embodiment of the invention will now be described, by way of nonlimiting example, with reference to the appended schematic drawings in which:

- Figure 1 is a schematic overview of a device according to the invention;

- Figure 2 is an exploded perspective view of the actuator used in the device of Figure 1; - Figures 3A, 6A and 7A are views in longitudinal section, along the lines IMA-IIIA, VIA-VIA and VIIA-VIIA of Figures 3B, 6B and 7B respectively, of the actuator of Figure 2, in different phases Operating; - Figures 4A, 5A and 8A are views in longitudinal section, along the lines IVA-IVA, VA-VA and VIIIA-VIIIA of Figures 4A, 5A and 8A respectively in their middle part and along the lines IVA-IVA, VA - VA and VIU'A-VIIΓA of FIGS. 4A, 5A and 8A respectively in their end parts, of the actuator in FIG. 2, in other operating phases; and

- Figures 3B to 8B are cross-sectional views along lines IIIB-IIIB to VIIIB-VIIIB of Figures 3A to 8A.

The device of FIG. 1 has the function of sequential gear shifting, using a lever 1, of a gearbox of which only the fork 2 of the first and second is shown. Reference may be made, for a more detailed description of such a function, to the document WO-96/23995 cited above.

The assembly constituted by the lever 1, the linkage 3, the pawl holder 4, and the barrel 5 conforms to the state of the art described in the aforementioned document, and will therefore not be described in more detail. It will be observed that the barrel selection track has not been shown, for which it is not necessary to provide assistance (although such assistance may be provided in accordance with the invention), nor d '' possible other passage tracks, associated with other gearbox forks, than track 6 for first and second passage from neutral, associated with fork 2.

This association is made by means of the track follower pin 7, integral with a support 8 of fork 2. The support 8 is itself fixed to the end of the rod 9 of the drawer 10 of the distributor cylinder 1 1 of assistance. The cylinder 1 1 is composed of an outer casing 12, a sleeve 13 rotatably mounted in the casing 12, and of the drawer 10 sliding in the sleeve 13. The sleeve 13 is integral with a pinion 14 meshing with a toothing 15 formed on the pawl holder to control the shirt in rotation. The gear ratio is here 1. The drawer 10 has three shoulders, a central 16 and two lateral

17 and 18 which delimit in the cylinder four chambers 19 to 22 respectively from the end of the jack opposite to the outlet of the rod 9. Two mortises 23 and 24 formed in the extension of one another inside and along a generatrix of the jacket 13, put in communication with the chambers 19 and 20 and, respectively, 21 and 22. The casing 12 has in its iongitudinal median part, in the same cross section, two orifices 25 and 26, angularly spaced, here 90 ° It also has in the plane of symmetry of these orifices 25 and 26, but opposite them, a third orifice 27 II finally has, on either side of the orifice 27 and on the same generator, qu3tπème and fifth orifices 28 and 29.

The openings 25 and 26 are connected by pipes 30 to the high pressure outlet 31 of a hydraulic pump 32, and the openings 27, 28 and 29 are connected by a pipe 33 to the reservoir 34 of the pump.

The jacket 13 has a central circular orifice 35 which, in the angularly neutral position of the jacket, is opposite the orifice 27 of the casing 12, and two oblong orifices 36 and 37 which are opposite screws of the holes 28 and 29 of the casing whatever the angular position of the jacket in the casing. It also has another circular orifice 38 diametrically opposite the orifice 35, between the ends of the mortises 23 and 24.

The operation of this device will now be described with reference to Figures 3 to 8.

Figures 3A and 3B show the actuator in the configuration it is in when the gearbox is in neutral. The fork 2 is in the middle position and the barrel is at the origin of the angular positions.

In this situation, the drawer 10, which is in the middle position in the casing 12 and the jacket 13, obstructs the supply orifices 25 and 26 and the cover 27. On the other hand, the chambers 19 and 22 are in communication with the cover holes 28 and 29 using mortises 23 and 24. The assistance is therefore inactive.

If the user actuates the lever 1 to engage the first gear, the pawl holder 4 rotates and drives the barrel 5 in a certain direction by means of one of its pawls. Via track 6 and pin 7, drawer 10 moves, here to the right. Figures 4A and 4B show the configuration of the actuator after a 30 ° rotation of the barrel. In this configuration, the jacket 13 has rotated 30 ° in the casing 12, which, combined with the translation of the drawer 10, closes the orifices 27 and 29. On the other hand, the orifice 28 remains open, and the orifice 25 or the orifice 26, depending on the direction of rotation of the jacket , is about to open. At this time, assistance is still inactive. For a rotation of the shirt 13 greater than 30 °, and up to 45 °

(Figures 5A and 5B), and an additional movement to the right of the drawer 10, corresponding to the engagement of the first speed, assistance becomes effective due to the supply of the chamber 22 through the orifice 25 or l orifice 26 with which it communicates by the mortise 24. It is observed that the orifice 29 is closed by the drawer 10 and that the orifice 27 is closed by the rotation of the liner 13 in the casing 12. On the other hand, the port 28 is open, which makes it possible to evacuate the hydraulic fluid from chamber 19 during

movement of the drawer 10 to the right, via the mortise 23. When the first gear is engaged, the lever 1 is released and is returned to the middle position by elastic means not shown. The pawl holder 4 and the sleeve 13 return to the original angular position, while the drawer 10 remains in abutment to the right, as shown in FIGS. 6A and 6B. In this configuration, the openings 27 and 28 are open, while the openings 25, 26 and 29 are closed. The assistance therefore produces no effort.

When the user acts again on the lever 1 to disengage the first gear and start to engage the second, it first causes a rotation of 30 ° of the pawl holder 4 and of the sleeve 13, in the same direction as before. Simultaneously, the slide 10 is brought back to the left, passes through its middle position when crossing neutral, and finds itself in the position of FIG. 7A symmetrical to that of FIG. 2A. The chamber 22 is emptied by the cover 27 then by the cover 29 by communication through the mortise 24, while the chamber 19 is filled by the orifice 28 and the mortise 23. The orifices 25 and 26 have been masked throughout this phase so that assistance has remained inactive.

Finally, when the user continues his action on the lever 1 to engage the second speed, the shirt 13 continues its rotation up to 45 ° (FIGS. 8A and 8B) by uncovering the orifice 25 or the orifice 26 and by masking the orifice 27, the orifice 28 remaining closed and the orifice 29 open. The chamber 22 can be emptied through the orifice 29 via the mortise o

24, while the chamber 19 is supplied by the orifice 25 or 26 via the mortise 23. The assistance is therefore effective.

When the user wishes to downshift from second to first, the operation is identical, except for the direction of rotation of the jacket 13 in the casing 12, the other of the orifices 25 or 26 being used.

It can therefore be seen that, in all cases of shifting from neutral, the drawer begins by positioning itself as a function of the direction of movement of the fork, while the assistance remains inactive. It is only at the expiration of this first phase that assistance becomes active, in the direction determined by prepositioning.

It will be observed that the chambers 19 and 22 could be connected by hydraulic pipes to annex chambers of the external jack.

Claims

1- Assistance device for gearbox in which a barrel (5) controls the movement of a fork (2), characterized in that it comprises an actuator (11) arranged for, in a first phase of passage from a speed from neutral, be set by the rotation of the barrel in a position for detecting the direction of movement of the fork, and in a second phase of the passage of said speed, assist a movement requested by the barrel downstream of the last.

2- Device according to claim 1, wherein said actuator is a hydraulic cylinder.

3- Device according to claim 2, wherein said cylinder comprises, between its housing (12) and a distributor drawer (10), a rotating jacket (13) whose rotation is controlled by the control of the barrel.

4- Device according to any one of claims 1 to 3, wherein the control of the barrel is a sequential control.

5- Device according to all of claims 3 and 4, wherein the jacket is rotated by a pawl holder (4) for controlling the barrel.

6- Device according to any one of claims 1 to 5, wherein a pin (7) track follower (6) is integral with said fork, said actuator being arranged to assist the movement of said pin and said fork. 7- Device according to all of claims 2 and 6, wherein the pin and the fork are integral with the rod (9) of said cylinder.