WO2005042996A1

WO2005042996A1 - Device for braking of a side axle in a gearbox

Info

Publication number: WO2005042996A1
Application number: PCT/SE2004/001479
Authority: WO
Inventors: Dag Nilsson
Original assignee: Scania Cv Ab (Publ)
Priority date: 2003-11-04
Filing date: 2004-10-15
Publication date: 2005-05-12
Also published as: SE524480C2; DE112004002102T5; SE0302891L; SE0302891D0

Abstract

An object of the present invention is to provide a simplified form of braking device in a gearbox, whereby the gearbox comprises a shaft (70) about which two gearwheels (50, 60) for different gears are supported for rotation, and a carrier device (40) arranged between the gearwheels, which carrier device is firmly attached to, for joint rotation with, the shaft and comprises a coupling sleeve (12) which is movable in the direction of the shaft for the generation and disengagement of gears, and first and second braking cone elements (30) arranged adjacent to first and second cone elements adjacent to the respective gearwheels. The braking device is characterised by the coupling sleeve being arranged for movement with a recess along a locking pin (20), which locking pin extends substantially in the direction of the shaft and has its ends arranged hingingly relative to the braking cone elements.

Description

Device for braking of a side axle in a gearbox

Technical field The present invention relates to a device for braking of a countershaft in a gearbox according to the preamble of claim 1. State of the art Fig. 9 illustrates a previously known synchronisation device 10' arranged between two shafts with associated gearwheels 50', 60'. The device comprises a shift sleeve 12' for engagement and disengagement of gears, which shift sleeve, when being manoeuvred towards either of the two gearwheels, carries with it a rigid body 20' firmly attached to cone elements 30', 32' which meet a cone element 54' arranged adjacent to the gearwheel concerned. When the one cone element 32' is moved towards the gearwheel 60', it meets the cone element 54', thereby braking and halting the gearwheel by mutual interaction of the cone elements. Movement of the shift sleeve 12' and the rigid body 20 towards the gearwheel 60' is at the same time hindered by the meeting of the cone elements. When the shift sleeve is subjected to a force which overcomes the braking moment, and to the engagement of a spring-loaded locking element 92' in a recess 24' in the rigid body, the shift sleeve moves further, while the rigid body remains stationary, so that the coupling teeth of the shift sleeve 12', which are in engagement with the coupling teeth of the carrier 40', come into engagement with the coupling teeth of the gearwheel 60'. Spring loading in a synchronisation device entails a certain complication of design. Summary of the invention An object of the present invention is to provide a simplified design of a braking device in a gearbox, whereby the gearbox comprises a shaft about which two gearwheels for different gears are supported for rotation and a carrier device is arranged between the gearwheels, which carrier device is firmly attached to, for joint rotation with, the shaft and comprises a coupling sleeve which is movable in the direction of the shaft for the engagement and disengagement of gears, and first and second braking cone elements arranged adjacent to first and second cone elements of the respective gearwheels. The braking device is characterised by the coupling sleeve being arranged for movement with a recess along a locking pin, which locking pin extends substantially in the direction of the shaft and has its ends arranged hingingly relative to the braking cone elements. The fact that the locking pin is arranged hingingly relative to the braking cone elements means that it can be placed obliquely. This oblique positioning means that at the time of a gearchange it locks the movement of the coupling sleeve so that the coupling sleeve transmits braking force via the locking pin to one of the braking cones. It is particularly appropriate to arrange the braking device between two gearwheels which rotate in mutually opposite directions so that they help to place the locking pin obliquely. hi one embodiment, the middle portion of the locking pin has a belly portion resulting in greater abutment against the coupling sleeve in an oblique state. Brief description of the drawings Fig. 1 depicts a cross-section in a gearbox equipped with a device for braking of a countershaft according to the present invention. Fig. 2 depicts a partial view of the device in Fig. 1 with a coupling sleeve attached to a carrier, and a locking pin arranged relative to two cone elements. Fig.3 depicts a partial view of a gearwheel of a gearchange mechanism arranged in association with one of the cone elements in Fig. 2. Fig.4 illustrates an overall view of two cone elements with three locking pins in accordance with the present invention. Fig. 5 depicts a partial view with a locking pin arranged relative to a cone element. Fig. 6 is a partial view of a section of Fig. 2 which illustrates the function of the invention in the engagement of a gear. Fig. 7 depicts an embodiment of the present invention with a modified locking pin. Fig. 8 illustrates a partial view of the embodiment in Fig. 7 in a section along the centreline of the locking pin. Fig. 9 illustrates a synchronisation device in a gearbox according to the state of the art. Description of preferred embodiments The invention concerns gearboxes in vehicles where the engine is connected, via the clutch and an input shaft, to a countershaft in the gearbox. Gearwheels are firmly attached to the countershaft and are in engagement with gearwheels of the various gears, which latter gearwheels are arranged for rotation about the gearbox shaft. These latter gearwheels thus rotate with the engine. So-called carriers are arranged relative to the main shaft of the gearbox, and the shaft is further connected to one or more driveshafts and further to one or more of the vehicle's road wheels. The carriers are attached firmly about, and rotate with, the gearbox shaft and therefore rotate when the road wheels rotate. Upon engagement of a gear, one of the gearwheels which rotate with the engine is connected to a corresponding carrier so that the engine is thus coupled to the road wheel or the driveshaft/driveshafts of the road wheels. By gear disengagement by means of the clutch pedal, the driver frees the engine from the gearwheels on the countershaft and, by manoeuvring the gear lever, connects a carrier to the gearwheel of the relevant gear. The gearwheel and carrier of the gear concerned may at this stage be rotating at different speeds, so gearboxes are equipped with synchronisation devices which adapt the rotation speeds of the gearwheel and carrier to one another. The present invention takes the form of a simplified synchronisation device which brakes the gearwheel and the carrier relative to one another. Fig. 1 depicts a cross-section in a gearbox equipped with a device 10 for braking a countershaft according to the present invention. Two gearwheels 50, 60 for two different gears are supported for rotation about the gearbox shaft 70. The two gearwheels 50, 60 are connected via two countershaft gearwheels 11, 13 to a countershaft 15 in the gearbox, which countershaft is further connected to the engine. The one gearwheel 60 is part of a crawl gear and is in direct contact with the countershaft gearwheel 13 arranged on the countershaft, while the other gearwheel 50 is part of a reverse gear and is connected, to the countershaft gearwheel 11 arranged on the countershaft, via a further gearwheel (not visible in the cross-section) for change of direction of rotation. A carrier 40 is arranged on the gearbox shaft 70 which is connected to driveshafts of the vehicle's road wheels. A coupling sleeve 12 for the engagement and disengagement of gears is arranged between the gearwheels 50, 60 of the crawl gear and reverse gear and is connected in a conventional manner to a gear lever (not depicted) in the vehicle. The coupling sleeve 12 is movable along a locking pin 20 which is arranged between two braking cone elements 30 adjacent to the two gearwheels 50, 60. Engaging the reverse gear entails the coupling sleeve 12 being moved, as illustrated in the diagram, along the locking pin towards the reverse gear gearwheel 50 so that coupling teeth (14 in Fig. 2) on the coupling sleeve are brought into engagement with coupling teeth (52 in Fig. 3) of the reverse gear. The reverse gear gearwheel 50 with the coupling teeth 52 is thus connected via the coupling teeth of the coupling sleeve 40 to coupling teeth 42 (Fig. 2) arranged on the carrier so that the reverse gear is connected to the gearbox shaft 70 and the engine is thereby connected via the reverse gear to the driveshaft of the road wheels. The function is described more clearly below in connection with Fig. 6. Fig. 2 is a partial view of the coupling sleeve 12, the locking pin 20, the braking cone elements 30 and part of the carrier 40. The coupling sleeve is arranged for axial movement relative to the carrier with teeth 14 in engagement with teeth 42 of the carrier. The locking pin 20 is arranged in a cylindrical recess 17 with insides 16 in the coupling sleeve. The locking pin comprises a cylindrical middle portion 22, cylindrical main portions 26 and spherically rounded end portions 28 arranged relative to the braking cone elements 30 in recesses 34. Between the middle portion 22 and the main portions 26, the locking pin has conical locking flanks 24 which broaden from the narrower middle portion to the thicker end portions. The recess 17 of the coupling sleeve is broadened at its apertures by conical edge portions 18. The diameter of the recess 17 is greater than the diameter of the locking pin's middle portion 22, a fact which combines with the spherical ball-joint shape of the end portions 18 to enable the locking pin to be placed obliquely relative to the gearbox shaft. The diameter of the recess 17 is the same as that of the locking pin's main portions 26, with the result that the obliquely positioned locking pin becomes aligned with the axial direction of the gearbox when the coupling sleeve 12 is moved along the locking pin towards either of the gear's two gearwheels. The carrier 40 is firmly attached to, for joint rotation with, the gearbox shaft by means of internal splines 44. Fig. 3 depicts part of the reverse gear gearwheel 50. The gearwheel is supported by a rolling bearing 56 about the gearbox shaft and is provided with said coupling teeth 52 and a cone element 54 which, upon engagement of the gear, meets and is braked by a cone 32 on the braking cone element 30. Fig. 4 depicts the braking cone elements 30 provided with three locking pins 20. The braking cone elements 30 comprise circular cones 32 arranged symmetrically about the gearbox shaft, which circular cones can meet and brake the cone elements 54 adjacent to the gearwheels of the gears, and hence the countershaft. Three locking pins are arranged in recesses 34 at equal spacings about the circumference of the cone elements 30. Fig. 5 illustrates how a locking pin is arranged in a braking cone element 30. Each end portion of the locking pin has a spherical ball-joint shape arranged in the cone element, and the latter' s side surface facing the gearbox shaft is in the form of an annular cone 32. The transition between the locking pin's main portion and end portion has a chamfered edge portion 27 for abutting against the cone element 30 when the locking pin is positioned obliquely. To illustrate the function of the device, Fig. 6 depicts various stages A-F during gear changing. Fig. 6 depicts a section along the centreline 6-6 in Fig. 2, corresponding to sectional views "from above" of Fig. 1. Fig. 6A depicts the locking pin 20 and the coupling sleeve 12 in a neutral state in which the locking pin's end portions 28 are arranged hingingly relative to the braking cone elements 30. When the engine is running and the clutch is disengaged, the crawl gear gearwheel and the reverse gear gearwheel (Fig. 1) rotate in mutually opposite directions. The braking cone elements 30 are then carried with the respective gearwheels, and the locking pin's end portions 28 follow with the cone elements in the gearwheels 50, 60 in the tangential direction of Fig. 1 so that the locking pin is positioned obliquely (Fig. 6B) relative to the gearbox shaft, which shaft is represented by the centreline 72. The insides 16 of the recess 17 and the shape of the locking pin, with a locking flank 24 arranged between a middle portion 22 and a main portion 26, cooperate to limit this oblique positioning. The coupling sleeve is provided (Fig. 6B) with edge portions 18 on the inside of the apertures of the recess, which edge portions during oblique positioning are arranged to meet the locking pin's locking flanks 24. When gear changing commences, the driver manoeuvring the gear lever causes the coupling sleeve to move along the locking pin towards the gear concerned, as illustrated by an arrow on the coupling sleeve in Fig. 6C. The locking pin's main portion 26 presses against one of the braking cone elements 30. The braking cone element 30 shifts towards the gearwheel to an extent d (illustrated in Fig. 6C) so that the gearwheel 50 (in Fig. 3) concerned is braked by the cone element 30 abutting against the gearwheel's cone element 54. The coupling sleeve moves further along the locking pin so that the inside 16 of the recess (Fig. 6D) meets the locking pin's main portion, resulting in the gearwheel being braked and becoming stationary relative to the coupling sleeve and hence also relative to the carrier 40 (in Figs. 1-2). The inside 16 of the coupling sleeve moves further in during abutment against the locking pin's main portion 26 (Fig. 6E) and the gear is engaged by the coupling sleeve's teeth 14 (see Figs. 1-2) being brought into engagement with the gearwheel's coupling teeth 52 (see Figs. 1 and 3). Fig. 6F depicts a final state (as in Fig. 1) in which the coupling sleeve 12 fully embraces the locking pin's main portion 26 and the reverse gear is engaged. Fig. 7 and Fig. 8 illustrate an embodiment of the invention. A coupling sleeve 12 is arranged about a locking pin 20 between two gearwheels 50, 60. The coupling sleeve is arranged in a carrier 40 which rotates with the gearbox shaft 70. The locking pin is arranged hingingly relative to the braking cone element 30 of each of the two gearwheels, h this embodiment the locking pin's middle portion 22 has a belly portion 23 such that the middle portion extends taperingly from the middle of the locking pin to the main portions. Fig. 8 depicts the locking pin in an oblique position in a section corresponding to that of Fig. 6. In this situation the middle portion abuts, on opposite sides of the belly portion 23, against the insides of the recess, while at the same time the locking flanks abut, at the apertures of the recess, against the recess edge portions 18. The locking pin's main portion has chamfered edges 27 which abut against the braking cone elements 30 at the apertures of the recess 34.

Claims

Claims 1. A device for braking of a countershaft (15) in a gearbox during gear changing, whereby the gearbox comprises a shaft (70) about which two gearwheels (50, 60) for different gears are supported for rotation, and a carrier device (40) arranged between the gearwheels, which carrier device is firmly attached to, for joint rotation with, the shaft and comprises a coupling sleeve (12) which is movable in the direction of the shaft for the engagement and disengagement of gears, and first and second braking cone elements (30) which are arranged adjacent to first and second cone elements (54) of the respective gearwheels c h ar a c t e r i s e d in that the coupling sleeve is arranged for movement with a recess along a locking pin (20), which locking pin extends substantially in the direction of the shaft and has its ends arranged hingingly relative to the braking cone elements.

2. A device for braking of a countershaft according to claim 1, whereby the different gears take the form of a reverse gear (50) and a crawl gear (60) and the two gearwheels rotate in mutually opposite directions.

3. A device for braking of a countershaft according to claim 1, in which the locking pin is further provided with a middle portion (22) and main portions (26) between its ends and the middle portion, and the coupling sleeve is movable along the middle portion and the main portions, and in which the middle portion and the recess (17) in the coupling sleeve allow oblique positioning of the locking pin relative to the shaft.

4. A device for braking of a countershaft according to claim 3, in which the middle of the locking pin has a belly portion (23) and the middle portion narrows from the belly portion to the main portions.

5. A device for braking of a countershaft according to claim 3, in which the middle of the locking pin is provided with two locking flanks (24) between the middle portion and the respective main portions, and the coupling sleeve is arranged to meet and cooperate with one of the locking flanks during gear changing.

6. A device for braking of a countershaft according to claim 5, in which the coupling sleeve and the locking pin are designed so that the coupling sleeve's cooperation with the locking flanks via the locking pin causes a movement (d) of one of the braking cone elements towards the cone element of one of the gearwheels.

7. A device for braking of a countershaft according to claim 1, in which the locking pin's ends have rounded end portions (28).

8. A device for braking of a countershaft according to claim 7, in which the braking cone elements each comprise an annular cone (32) and have recesses (34) for the respective rounded end portions (28).

9. A device for braking of a countershaft according to claim 8, whereby at least three locking pins are arranged in recesses along the circumference of each of the annular cones.