Intermediate gear shift arm

Abstract

The invention relates to a device (1) for the internal actuation of a gearbox, comprising a main shaft (1) mounted so as to be slidable through a housing (3, 4), the main shaft (1) having a lateral extension (2) capable of acting on an intermediate arm (14) designed to guide a gear shift fork (8), the intermediate longitudinal member (14) being mounted so as to be translatable relative to the housing (3, 4).

Description

[Technical field]

[0001] The present invention relates to an actuation device for selecting and changing gears in a vehicle gearbox, in particular a semi-automatic gearbox.

[0002] The invention aims to provide an internal gearbox actuator which is particularly accurate in positioning. [Background technology]

[0003] Actuating devices are known which allow the selection and changing of gears using an actuator in a gearbox. Such devices usually have a fork used to change the gear, which is moved in translation by a selector finger via an elongated interface. For design reasons, the fork may be moved away from the selector finger. Since the risk of deformation of the interface increases with its length, it is known to reduce this risk by using a support element fixed to the casing of the gearbox, which absorbs the forces applied to the interface via a pivot connection between the support element and the interface.

[0004] However, this solution results in inaccurate positioning of the forks and reverses the direction of movement of the forks relative to the selector fingers, which is undesirable in a semi-automatic gearbox. Summary of the Invention

[0005] The present invention aims to overcome at least some of the above mentioned drawbacks and to propose a more compact actuator with improved accuracy and reliability.

[0006] The present invention therefore relates to an internal gearbox actuation device comprising a main shaft slidably mounted through a casing and including a lateral extension designed to act on an intermediate arm used to move a gear shift fork, the intermediate longitudinal member being mounted for translation relative to the casing.

[0007] In one embodiment, the gear shift fork is disposed on the second shaft.

[0008] According to one embodiment, the intermediate longitudinal member is attached to a third shaft.

[0009] Preferably, a third shaft is slidably mounted through the casing and the intermediate longitudinal member is fixed to the third shaft.

[0010] The lateral extension of the main shaft may be designed to cooperate with a slot in the intermediate arm.

[0011] Advantageously, the intermediate longitudinal member has a slot designed to cooperate with a projection from the gear shift fork.

[0012] For example, the protrusion from the fork has a rectangular cross section.

[0013] Preferably, at least one of the first, second and third shafts is slidably mounted in a bearing mounted in the casing.

[0014] Advantageously, an anti-rotation device is provided to limit the angular deviation of the intermediate arm.

[0015] In one embodiment, the anti-rotation device comprises a translation guide means for the intermediate arm.

[0016] The invention will be further described with reference to embodiments illustrated in the accompanying drawings, given as non-limiting examples. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 illustrates a gearbox actuator according to the prior art. [Diagram 2] 1 is a perspective view of an embodiment of an actuator; [Diagram 3] FIG. 3 is another perspective view of the actuator of FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] FIG. 1 shows an internal gearbox actuation device described in patent application FR3026808A1. This device has several actuation elements for enabling gear shifting, in particular a main shaft A1 slidably mounted in a casing C0 and including a lateral extension D0 designed to act on an intermediate arm B0 designed to move a gear shift fork F0, which intermediate arm B0 is mounted rotatably relative to the casing C0 about a pivot connection P0 on a support element S0 provided on the casing C0. The pivot P0 is provided to absorb the forces exerted on the intermediate arm B0 when the finger D0 rotates the arm B0 to move the fork F0. As shown, the direction of translational movement of the fork F0 is opposite to that of the finger D0. Moreover, in this device misalignment of the pivot P0 and the finger D0 relative to the casing C0 accumulates, which leads to unwanted rotation of the arm B0 about the pivot P0 and thus to inaccurate positioning of the fork F0. These problems necessitate the use of tighter manufacturing tolerances for the actuators, and especially precise position sensors.

[0019] 2 and 3 show an embodiment of an actuating device according to the invention, which is provided in a gearbox for the internal control of gear shifting and is designed to cooperate with a casing 3, 4 of the gearbox.

[0020] The "casing" refers in particular to the structural part of the gearbox, including one or two members in which the actuating device is assembled. Thus, each shaft slidably mounted through the casing 3, 4 may be mounted through one or more members of the casing 3, 4.

[0021] The device comprises a main shaft 1 slidably mounted through at least one member of the casing 3 , 4 , and a second shaft 7 including a gear shift fork 8 .

[0022] Unlike the prior art, the intermediate arm 14 is mounted for translation relative to the casings 3, 4. Said arm transmits to the forks 8 the translational movement of the lateral extension 1 which is rigidly connected to the main shaft 1.

[0023] In one embodiment, the fork 8 may be translationally guided by the second shaft 7 .

[0024] A second shaft 7 is slidably mounted through the casings 3, 4 and a fork 8 is connected to the second shaft 7 so as to be unable to move in translation.

[0025] The longitudinal member 14 may also be translationally guided by a third shaft 15 .

[0026] When the longitudinal member 14 transmits the translational movement of the shaft 1 to the fork 7, the third shaft 15 absorbs the forces, in particular the shear forces, applied to the longitudinal member 14.

[0027] A third shaft 15 is slidably mounted through the casings 3, 4 and the longitudinal member 14 is fixed to the third shaft 15 by the hub 13 of the arm 14 assembled to the shaft 15, for example by a hoop or pin.

[0028] The main shaft, the second shaft and the third shaft are cylindrical extensions which at least partially traverse the elements of the casing 3, 4. Said shafts are made from a material which includes aluminium.

[0029] The main shaft 1 includes a lateral extension 2 designed to cooperate with a slot 14a of the arm 14. The lateral extension 2 is, for example, a finger 2 of circular or square cross section extending approximately perpendicularly to the main shaft 1.

[0030] The longitudinal member 14 may have a slot 14b designed to cooperate with a projection 12 from the gear shift fork 8. Thus, the fork 8 is connected to the arm 14 when the projection 12 cooperates with the slot 14b, and is decoupled from the arm 14 when it does not.

[0031] Nevertheless, other types of parts may be used to prevent rotation of the arm 14 without departing from the scope of the invention. In particular, the projection 12, the rod 18 and the lateral extension 19 may have a flat or rectangular cross section.

[0032] The main shaft 1, the second shaft 7 or the third shaft 15 are slidably mounted relative to the casings 3, 4, for example via bearings 10, 11, 17 mounted in or fixed to the casings 3, 4. The third shaft 15 can be fixed to the casing 3, 4, in which case the longitudinal member 14 is slidably mounted relative to the third shaft 15.

[0033] The bearings 10, 11, 17 are, for example, split rings made from a material including metal, with an inner lining made from polytetrafluoroethylene (PTFE).

[0034] As shown in Figure 3, an anti-rotation device is provided to limit the angular displacement of the arm 14 about the third shaft 15. Said device comprises a translational guide for the arm 14, such as a rod 18 connected to the casings 3, 4 and passing through an annular shaft 16 provided on the longitudinal member 14.

[0035] The clearance between the shaft and the bearings, particularly the clearance defined by the diameter of the rod 18 and the tube 16, must be large enough to allow the longitudinal member 14 to slide freely, yet small enough to limit the angular play of the longitudinal member 14.

[0036] For shafts 1, 7, 15, 18 with diameters between 10 mm and 18 mm (f7 fit), the manufacturing tolerances are substantial at around 9 μm.

[0037] Each ring 10, 11, 16, 17 may have a seat with a cross section of 12 mm to 20 mm (H7 fit) mounted on the casing 3, 4. For each seat the manufacturing tolerance is substantially around 15 μm.

[0038] After being fitted into the casings 3 and 4, the sliding clearances of the shafts 1, 7, 15, and 18 at the rings 10, 11, 16, and 17 are 6 μm to 128 μm.

[0039] Consequently, when changing gears, the forces transmitted to the arm 14, which is rigidly connected to the third shaft 15, are absorbed by the ring 17, which helps to limit the forces on the shaft 15 and therefore its deformation. This actuation device therefore helps to improve the positioning accuracy of the fork and thus to achieve more precise control of the gear shifting.

Claims

1. An internal gearbox actuator comprising a main shaft (1) slidably mounted through a casing (3, 4) and including a lateral extension (2) designed to act on an intermediate longitudinal member (14), which is an intermediate arm used to move a gear shift fork (8), 1. A device according to claim 1, wherein the intermediate longitudinal member (14) is mounted for translation in the axial direction of the main shaft (1) relative to the casing (3, 4), the intermediate longitudinal member (14) having a slot (14b) designed to cooperate with a projection (12) from the gear shift fork (8), the gear shift fork (8) being connected to the intermediate longitudinal member (14) when the projection (12) cooperates with the slot (14b) and being separated from the intermediate longitudinal member (14) otherwise.

2. 2. The device according to claim 1, wherein the gear shift fork (8) is arranged on a second shaft (7).

3. 3. Apparatus according to claim 1 or 2, wherein the intermediate longitudinal member (14) is attached to a third shaft (15).

4. 4. The device according to claim 3, wherein the third shaft (15) is slidably mounted through the casing (3, 4) and the intermediate longitudinal member (14) is fixed to the third shaft (15).

5. 5. The device according to any one of claims 1 to 4, wherein the lateral extension (2) of the main shaft (1) is designed to cooperate with a slot (14a) of the intermediate longitudinal member (14).

6. 6. The device according to claim 1, wherein the protrusion (12) has a rectangular cross section.

7. 7. Apparatus according to any one of claims 1 to 6, wherein at least one of the main, second and third shafts (1, 7, 15) is slidably mounted in a bearing (10) mounted in the casing (3, 4).

8. 8. Apparatus according to any one of the preceding claims, comprising an anti-rotation device (16) designed to limit angular misalignment of the intermediate longitudinal member (14).

9. 9. Apparatus according to claim 8, wherein the anti-rotation device comprises translational guide means (18) for the intermediate longitudinal member (14).

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