WO2012070998A1

WO2012070998A1 - Device for manual gearchange in a gearbox of a vehicle

Info

Publication number: WO2012070998A1
Application number: PCT/SE2011/051375
Authority: WO
Inventors: Kenneth Hammarstedt
Original assignee: Scania CV AB
Current assignee: Scania CV AB
Priority date: 2010-11-26
Filing date: 2011-11-16
Publication date: 2012-05-31
Anticipated expiration: 2013-05-26
Also published as: SE536037C2; SE1051244A1

Abstract

The present invention relates to a device for manual gearchange in a gearbox (2) of a vehicle. The vehicle comprises an engine (7), a gear lever (1) for manual gearchange in the gearbox (2), a movement-transmitting mechanism intended to transmit the gearchange movements of the gear lever (1) to the gearbox (2), and a clutch mechanism (8, 35) by which it is possible to disconnect the gearbox (2) from the engine (7). The device comprises a locking means (22) which can be put into a non- locking state in which it allows gearchange movements from the gear lever (1) to be transmitted to the gearbox (2), and into a locking state in which it blocks gearchange movements of the gear lever (1) so that the gear lever (1) cannot move from a current gear position, and an activation device (33, 34) adapted to putting the locking means (22) into a non-locking state at times when the clutch mechanism (8, 35) has disconnected the gearbox (2) from the engine (7), and to putting the locking means (22) into the locking state at times when the clutch mechanism (8, 35) has not disconnected the gearbox (2) from the engine (7).

Description

Device for manual gearchange in a gearbox of a vehicle

BACKGROUND TO THE INVENTION AND PRIOR ART The invention relates to a device for manual gearchange in a gearbox of a vehicle according to the preamble of claim 1.

Many drivers drive vehicles in a very rough way. To effect a gear change, the driver pulls the gear lever out of the current gear position and pushes it into a different gear position without having fully depressed the clutch pedal. Such a mode of driving causes damage and wear on components of the gearbox and particularly on its gearwheels and the components which synchronise the speeds of the shafts in the gearbox which are provided with gearwheels.

US 5,695,029 refers to an automatic gearbox for a vehicle whereby the movement of a gear lever can be blocked in various operating situations. The purpose of such blocking seems to be to prevent the gear lever from being mistakenly moved to inappropriate positions in certain operating situations. The blocking can be

deactivated by pressing a button situated close to the gear lever.

SUMMARY OF THE INVENTION

The object of the present invention is to propose a device which allows only a correct gearchange process to take place when changing gear in a manual gearbox in a vehicle.

The above object is achieved with the device mentioned in the introduction which is characterised by what is indicated in the characterising part of claim 1. The device thus comprises a locking means which locks the gear lever in a gear position until the clutch mechanism has disconnected the gearbox from the engine. This means that it is not possible to pull the gear lever out of one gear in the gearbox and push it into another gear before the gearbox has been acceptably disconnected from the engine. Thus only after complete disconnection of the gearbox from the engine can the gearchange process take place correctly and be effected. The device thus makes it possible to prevent damage and wear caused to components of the gearbox by a driver's incorrect gearchanging behaviour. According to a preferred embodiment of the present invention, the locking means comprises a variable-length force means connected to a component of the movement- transmitting mechanism. A variable- length force means can easily be put into a locking state by being connected to a medium from a pressure medium source. The variable-length force means can be put into a non-locking state by being connected to a medium source at a lower pressure which may be equal to the pressure of the surroundings. The movements of a gear lever are thus transmitted via a movement- transmitting mechanism to the gearchanging components in the gearbox. Blocking of the movement of one of the components of the movement-transmitting mechanism by the variable- length force is usually sufficient to prevent blocking of the gear lever in a current gear position.

According to a preferred embodiment of the present invention, the variable-length force means is connected to a gearshift shaft of the movement-transmitting mechanism in such a way that in the locking state it prevents rotary motion of the gearshift shaft in at least one direction. At times when a gear is being disengaged and another is being engaged, the gearshift shaft performs a rotary motion in the gearbox. Usually, half of the gears are engaged by a clockwise rotary motion of the gearshift shaft from a neutral state, while the other half of the gears are engaged by an anticlockwise rotary motion of the gearshift shaft from the neutral state. Knowing which gear is engaged therefore means that locking of the rotary motion of the gearshift shaft in a rotary direction by the locking means is sufficient to block the gear lever in a current gear position. With advantage, the variable- length force means is connected to the gearshift shaft via a lever arm. This makes it possible for even a moderately powerful force means to cause a relatively large rotary action in order to counteract a rotary motion of the gearshift shaft and block the gear lever in a current gear position. According to another embodiment of the invention, the variable- length force means has a stationary portion connected to a housing which encloses the gearbox. To enable it to block the movement of a component in the movement-transmitting mechanism, it is appropriate that the force means has a stationary fastening. The stationary portion of the force means may with advantage be fastened in a housing which encloses the components of the gearbox, although it is possible for the stationary portion of the force means to be fastened in any stationary component close to the gearbox.

According to a preferred embodiment, the variable-length force means is a pneumatic cylinder. Such a cylinder has a space close to a piston which is connected to a piston rod. The piston rod is itself connected to a component of the movement-transmitting mechanism. When compressed air is supplied to the space, the piston rod is moved by the piston to a position where it blocks said component of the movement-transmitting mechanism. When the space is connected to air at the pressure of the surroundings, blocking of said component of the movement-transmitting mechanism ceases.

Alternatively a hydraulic cylinder may be used. The variable- length force means is with advantage double-acting. If the force means is a pneumatic double-acting cylinder, it will have two spaces on opposite sides of the piston. When compressed air is supplied to one of said spaces, the piston rod is moved by the piston to a first position where it can block the gearshift shaft in a first rotary position. When compressed air is supplied to the opposite space, the piston rod is moved by the piston in an opposite direction to a second position where it can block the gearshift shaft in a second rotary position.

According to another preferred embodiment of the present invention, the activation device is a control unit adapted to receiving information about whether the gearbox is or is not disconnected from the engine and to controlling the activation of the locking means on the basis of this information. The control unit may be a computer unit with suitable software for the purpose. With advantage the control unit is adapted to receiving information from a sensor which monitors the position of a clutch pedal of the clutch mechanism. Said sensor may monitor the position of any desired movable component of the clutch in order to inform the control unit about whether the gearbox is or is not disconnected from the engine. The clutch pedal has to be depressed by the driver to disconnect the gearbox before a gearchange process takes place. In this case said sensor thus monitors when the clutch pedal has been depressed from the initial position. The clutch pedal may be movable between an initial position and a depressed extreme position and the control unit be adapted to controlling the activation of the locking means so that it will be in the locking state until the clutch pedal has moved to a disconnecting position at a predetermined distance from the initial position. For a gearchange process to take place in a desired manner, the gearbox needs to be fully disconnected from the engine. Such is the case when the clutch pedal has moved a specific distance from the initial position. This distance may be example be 80% of the total distance between the initial position and the depressed extreme position. The clutch pedal will not usually need to be fully depressed for the gearbox to be fully disconnected from the engine.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention is described below by way of example with reference to the attached drawings, in which:

Fig. 1 depicts part of a vehicle with a gearbox and an engine and

Fig. 2 depicts a device for manual gearchange according to the present invention.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION Fig. 1 depicts schematically a gear lever 1 for a gearbox 2. The gear lever 1 is arranged to be movable in a conventional way to predetermined gear positions in order to engage various different gears in the gearbox 2. The movements of the gear lever 1 in the vehicle's transverse direction are transmitted via a first movement-transmitting mechanism which comprises a first wire 3. The first wire 3 has an extent from a first lever arm la of the gear lever to a first housing 4 situated in the gearbox 2. The movements of the gear lever 1 in the vehicle's longitudinal direction are transmitted via a second movement-transmitting mechanism which comprises a second wire 5. The second wire 5 has an extent from a lever arm lb of the gear lever to a second housing 6 situated in the gearbox 2. Gearchange movements via the second wire 5 result in engagement/disengagement of the various gears in the gearbox 2. The gearbox 2 is situated in a vehicle which is powered by an engine 7. The vehicle is provided with a schematically depicted clutch 8 situated between an output shaft 7a of the engine 7 and an input shaft 2a of the gearbox.

Fig. 2 depicts the first movement-transmitting mechanism and the second movement- transmitting mechanism close to the gearbox 2. The first movement-transmitting mechanism comprises, after the first wire 3, an arm 9 which has a first end connected to the first wire 3 and a second end adapted to being pivotable about an articulation 10. The arm 9 is provided with a firmly attached forklike means 11. The forklike means 11 has a recess to accommodate a protruding element 12 which is mounted firmly on a gearshift shaft 13. The gearshift shaft 13 is supported for rotation and linear movement in at least two bearings 14 depicted schematically in Fig. 2. When the gear lever 1 is moved sideways between two gear positions, this results in a movement which is propagated via the first wire 3. The wire 3 thus causes the arm 9 to pivot about the bearing point 10. The forklike means 11 is thus rotated and moves the gearshift shaft 13 in an axial direction via the firmly attached protruding element 12. A gearshift 13a here viewed schematically from above is firmly attached to the gearshift shaft 13. The gearshift 13a, which effects engagement and disengagement of gears in the gearbox 2, is arranged to be movable by the first movement-transmitting mechanism in the longitudinal direction of the gearshift shaft 13. The second movement-transmitting mechanism comprises, after the second wire 5, a lever arm 15 situated in a housing 6. The lever arm 15 has a first end firmly connected to the second wire 5, and an intermediate portion supported for pivoting about an articulation 16. The second end of the lever 15 is provided with a recess 17 adapted to accommodating a protruding element 18 which is firmly attached to a cylindrical clutch element 19. The clutch element 19 has at an end surface a coaxial connection to a rod 20. The rod 20 has firmly attached to it an element 20a which is in contact with a means 13b which is itself firmly attached to the gearshift shaft 13. Linear movement of the rod 20 is converted by the element 20a and the means 13b to rotary motion of the gearshift shaft 13. Rotary motion of the gearshift shaft 13 results in corresponding rotary motion of the gearshift 13a and consequent engagement or disengagement of a gear in the gearbox 2. A current gear is disengaged and a different gear is engaged by means of the second movement-transmitting mechanism.

A lever arm 21 has an end attached to the gearshift shaft 13. The lever arm 21 has an opposite end connected articulatably to a movable end portion of a double-acting pneumatic cylinder 22. The double-acting pneumatic cylinder 22 has an opposite stationary end portion articulatably fastened in a housing 23 which encloses the components of the gearbox. The double-acting pneumatic cylinder 22 has a first space 24 and a second space 25 on opposite sides of a movable piston 26. The piston 26 is connected to a piston rod 27. The cylinder's first space 24 is connected to a compressed air source 28 by a line 29. The line 29 comprises a three-way valve 30 by means of which the cylinder's first space 24 can be connected to the compressed air source 28 or to surrounding air. The cylinder's second space 25 is connected to the compressed air source 28 by a line 31. The line 31 comprises a three-way valve 32 by means of which the cylinder's second space 25 can be connected to the compressed air source 28 or to surrounding air. An electrical control unit 33 is adapted to controlling the three-way valves 30, 32. The electrical control unit 33 is adapted to receiving information from a sensor 34 which monitors the position of a clutch pedal 35 which is movable from an initial position 35a to a fully depressed extreme position 35b.

The control unit 33 has suitable access to information about which gear is engaged in the gearbox 2. The gearshift 13a engages in this case odd-numbered gears by clockwise rotary motion of the gearshift shaft 13 from a neutral state, and even- numbered gears by anticlockwise rotary motion of the gearshift shaft 13 from the neutral state. The control unit 33 receives information substantially continuously from the sensor 34 about the position of the clutch pedal 35. When the clutch pedal 35 is in the initial position 35a, the control unit 33 connects one of the cylinder's spaces 24, 25 to the compressed air source 28 and the other space to surrounding air via the three- way valves 30, 32. When the first space 24 is connected to compressed air and the second space 25 to surrounding air, the cylinder will be of maximum length. In this case the gearshift shaft 13 is locked in a clockwise rotary position relative to a neutral state. When the second space 25 is connected to compressed air and the first space to surrounding air, the cylinder will be of minimum length. In this case the gearshift shaft 13 will be in an anticlockwise rotary position relative to the neutral state.

Depending on whether the gear engaged is odd-numbered or even-numbered, compressed air is supplied from the compressed air source to one of the cylinder's spaces 24, 25 when the clutch pedal 35 is in the initial position 35a. To be able to effect a gearchange movement, the driver has to depress the clutch pedal 35 before the blocking of the gear lever 1 ceases. When it receives information from the sensor 34 that the clutch pedal 35 has moved to a predetermined distance from the initial position 35a to a disconnecting position 35c, the control unit 33 will find that the input shaft 2a of the gearbox is fully disconnected from the engine shaft 7a. Said predetermined distance may be about 80% of the distance between the clutch pedal's initial position 35a and its fully depressed extreme position 35b. The control unit 33 will then put the three-way valves 30, 32 into positions such that both of the cylinder's spaces 24, 25 are connected to surrounding air. The gearshift shaft 13 will thus be free to rotate in desired directions. The driver can then move the gear lever 1 from a current gear position to a desired different gear position. The lines 29, 31 are of relatively small diameter. The pressure in the space 24, 25 which is connected to the compressed air source 28 will therefore not drop immediately when it is connected to surrounding air. The result is an initial resistance to the gear lever 1 when it is moved from the current position. However, this initial resistance will decrease relatively quickly when the pressure in the respective space 24, 25 drops. So long as the clutch pedal 35 is depressed, the gear lever 1 can be moved to any desired gear position. When the driver releases the clutch pedal 35 to above said predetermined

disconnecting position 35b, a different gear will have been engaged in the gearbox. The control unit 33 registers which gear has thus been engaged. The control unit 33 then controls the valves 30, 32 so that the compressed air source 28 is connected to the cylinder's space [PAGE 7 LINE 3 READING SINGULAR "utrymme"] 24, 25 at which the cylinder 22 blocks the gear lever 1 in the changed gear position. The invention is in no way restricted to the embodiment described but may be varied freely within the scopes of the claims.

Claims

1. A device for manual gearchange in a gearbox (2) of a vehicle which comprises an engine (7), a gear lever (1) for manual gearchange in the gearbox (2), a movement- transmitting mechanism intended to transmit the gearchange movements of the gear lever (1) to the gearbox (2), and a clutch mechanism (8, 35) by which it is possible to disconnect the gearbox (2) from the engine (7), which device comprises a locking means (22) which can be put into a non-locking state in which it allows gearchange movements from the gear lever (1) to be transmitted to the gearbox (2), and into a locking state in which it blocks gearchange movements of the gear lever (1) so that the gear lever (1) cannot move from a current gear position, and an activation device (33, 34) adapted to putting the locking means (22) into the non- locking state at times when the clutch mechanism (8, 35) has disconnected the gearbox (2) from the engine (7), and to putting the locking means (22) into the locking state at times when the clutch mechanism (8, 35) has not disconnected the gearbox (2) from the engine (7),

characterised in that the locking means comprises a variable-length force means (22) connected to a gearshift shaft (13) of the movement-transmitting mechanism in such a way that in the locking state it prevents rotary movements of the gearshift shaft (13) in at least one direction, and in that the variable-length force means (22) is connected to the gearshift shaft (13) via a lever arm (21).

2. A device according to claim 1, characterised in that the variable-length force means (22) has a stationary portion connected to a housing (23) which encloses the components of the gearbox.

3. A device according to either of claims 1 and 2, characterised in that the variable- length force means is a pneumatic cylinder (22).

4. A device according to claim 3, characterised in that the pneumatic cylinder (22) comprises at least one space (24, 25) which is connectable to a compressed air source when the cylinder is in the locking state, and to surrounding air when the cylinder is in the non- locking state.

5. A device according to any one of the foregoing claims, characterised in that the activation device comprises a control unit (33) adapted to receiving information about whether the gearbox (2) is disconnected from the engine (7), and to controlling the activation of the locking means (22) on the basis of that information.

6. A device according to claim 5, characterised in that the control unit (33) is adapted to receiving information from a sensor (34) which monitors the position of a clutch pedal (35) of the clutch mechanism.

7. A device according to claim 6, characterised in that the clutch pedal (35) is movable between an initial position (35 a) and a depressed extreme position (35b) and that the control unit (33) is adapted to controlling the activation of the locking means so that it will be in the locking state until the clutch pedal (35) is moved to a disconnecting position (35 c) at a predetermined distance from the initial position (35 a).