SHIFT LEVER AND METHOD FOR MANOEUVRING AN AUTOMATIC TRANSMISSION

Abstract: The invention relates to a gear shift (22) for operating an automated transmission (11, 12) for a motor vehicle which comprises a disengagement arrangement (12) positioned in the drive line between the engine (10) and the gearbox (11) of the vehicle. The gearbox can be operated between a neutral position and at least one drive position by operating the gear shift between a corresponding neutral position (N) and at least one corresponding drive position (D). In order to make possible rapid operation of the gearbox, a detector is arranged so as to detect an actuation of the gear shift (22), which detector is connected to operating means (17, 18) for activating the disengagement arrangement (12).

Description: TITLE Shift Lever and Method for Manoeuvring an Automatic Trans- mission. TECHNICAL FIELD The present invention relates to a gear shift for operating an automated transmission for a motor vehicle which comprises a disengagement arrangement positioned in the drive line between the engine and the transmission of the vehicle, which transmission can be operated between a neutral position and at least one drive position by operating the gear shift between a corresponding neutral position and at least one corresponding drive position. The invention also relates to a method for operating an automated transmission. BACKGROUND Automated gearboxes have recently become increasingly common in trucks. Such gearboxes are in principle manual gearboxes in which the gear lever has been replaced by an automation means. This includes both electronics for selection of a new gear and actuators for engaging and disengaging the gears. In a vehicle with an automated gearbox, there is no conventional gear lever in the driver's compartment; instead there is a gear selector with electric change- over switches for detecting the gear position selected. When a gearbox is operated from one gear position to another, the old gear position must first be disengaged from the engagement position. The speed of rotation of the running wheels of the new gear position must then be speed-adapted to one another before these running wheels can be brought together. In manual gearboxes, this speed adaptation is as a rule brought about by synchronizing devices which serve as a brake between clutch sleeve and running wheels. For inter alia reasons of cost, the synchronizing devices are often removed in automated gearboxes. Speed adaptation is then achieved by controlling the speed of rotation of the engine, which means that the clutch does not have to be disengaged on shifting gear when the vehicle is in motion. In order to speed up the speed adaptation on upshifting, when the input shaft system is to be slowed down, unsynchronized automatic gearboxes are . often equipped with what is known as a gearbox brake. The gearbox brake can also be used on starting a stationary vehicle. In this connection, the engine is running, the clutch is not disengaged, and the gear selector is in neutral position, for example after power take-off operation. In this case of application, the input shaft system of the gearbox rotates while the output shaft system is stationary. When the gear selector is moved into a drive position (forward or reverse) , engagement of a gear in order to drive off (that is to say the starting gear) can begin. In this connection, the adaptation of the speed of rotation of the running wheels of the starting gear cannot take place by controlling the engine speed (this would in that case require the engine to be switched off) . Instead, the following procedural steps must be performed: 1. disengagement of the gearbox from the output shaft of the engine, 2. reduction of the speed of rotation of the input shaft system, for example by a gearbox brake, 3. engagement of starting gear when the speed of rotation of the running wheel concerned is sufficiently low. The gearbox brake increases complexity and cost. Removing it, however, means that the speeds of the input shaft system can be reduced only as a consequence of the inner frictional resistance of the gearbox. A period of time of roughly 2 seconds is normally needed in order to bring the speed of rotation down to the desired level in this way in order to make it possible to engage the starting gear. As this time delay takes place after the driver has moved the gear selector into the new position, the delay is experienced as a very negative effect. DISCLOSURE OF THE INVENTION One object of the invention is therefore to produce a control means which makes it possible to use an automated gearbox without a gearbox brake, which does not have the disadvantages described above. To this end, the .control means according to the invention is characterized in that a detector is arranged so as to detect an actuation of the gear shift, which detector is connected to operating means for activating the disengagement arrangement. By virtue of this design of the control means, the disengagement arrangement can be activated more rapidly for reducing the time required for a gear- shifting operation. The method according to the invention is characterized by the steps of detecting an actuation of the gear shift, and of activating the disengagement arrangement in the event of such a detection. Further advantageous variants of the invention emerge from the subclaims. BRIEF DESCRIPTION OF FIGURE The invention will be described in greater detail below with reference to an illustrative embodiment which is shown in the accompanying drawing which shows a schematic block diagram of an internal combustion engine with an automated transmission and a gear shift according to the invention. DESCRIPTION OF ILLUSTRATIVE EMBODIMENT The figure shows schematically a drive line belonging to a vehicle and comprising an engine 10, a gearbox 11 and a clutch 12 positioned between the engine and the gearbox. The gearbox 11 can, for example, be provided with what is known as a split unit which provides two possible gearings from the input shaft to the intermediate shafts. The basic unit of the gearbox can be provided with four forward gears and a reverse gear. The gearbox can also comprise what is known as a range unit which provides another two possible gearings from the main shaft to the output shaft. In total, there are then 16 forward gears, and four reverse gears. The clutch 12 is mechanical and provided with a side 13 connected to the engine 10 and also a disengageable, output side 14 which is connected to the gearbox 11 via an input shaft 15. An output shaft 16 from the gearbox is connected in a known manner to the driving wheels of. the vehicle. Operation of the clutch 12 is effected by means of a control device 17 which is operated by a microcomputer-based control unit 18 via an output 19. Input data to the control unit 18 is received, for example, via a connection 20 to the engine 10, which' provides information about the current engine speed. The control unit 18 also receives information about the current gear position via a connection 21. The connections 20 and 21 are two-way connections, which makes it possible, for example, for the control unit 18 on the one hand to influence the engine speed by activating a suitable arrangement, for example an exhaust brake, and on the other hand to control the gear position of the gearbox as well. The control unit 18 also receives input data from a gear selector 22 via a connection 23. The gear selector 22 is provided with a lever 24 with a neutral position lock 25 and has three possible use positions illustrated in the figure: N for neutral position, D for drive (forward) position and R for reverse. More positions on the selector are possible, as are more knobs. The gear selector 22 is provided with a detector (not shown) which is arranged so as to sense whether the lever 24 is actuated, for example by the lever being moved from the N position. Alternatively, the detector is arranged so as to sense whether the neutral position lock 25 has been pressed in, which takes place before the gear selector can leave the N position. The signal from the detector activates the control device 17 via the connections 19, 23 and also the control unit 18, the clutch 12 being disengaged. The adaptation of the speed of rotation of the running wheels of the gearbox can then take place without delay, either through the effect of the inner rotational resistance of the gearbox, or by using a gearbox brake. On detection of the desired speed of rotation for • engaging a gear having been obtained, the shifting operation takes place automatically via the control unit 18. The gear selector described above therefore makes possible rapid engagement of a starting gear, without the need for a gearbox brake for adapting the speed of rotation of the running wheels of the starting gear. The invention is not to be considered as being limited to^ the illustrative embodiments described above, but a number of further variants and modifications are possible within the scope of the patent claims below.

Claims: PATENT CLAIMS 1. A gear shift (22) for operating an automated transmission (11, 12) for a motor vehicle whic comprises a disengagement arrangement (12) positioned in the drive line between the engine (10) and the gearbox (11) of the vehicle, which gearbox can be operated between a neutral position and at least one drive position by operating the gear shift between a corresponding neutral position (N) and at least one corresponding drive position (D) , characterized in that a detector is arranged so as to detect an actuation of the gear shift (22) , which detector is connected to operating means (17, 18) for activating the disengagement arrangement (12) . 2. The gear shift as claimed in claim 1, characterized in that the detector is adapted to detect a movement of the gear shift (22) from the neutral position (N) . 3. The gear shift as claimed in claim 1, characterized in that the detector is adapted to detect an actuation of a neutral position lock (25) arranged at the gear shift (22) . 4. A method for operating an automated transmission (11, 12) for a motor vehicle which comprises a disengagement arrangement (12) positioned in the drive line between the engine (10) and the gearbox (11) of the vehicle, which gearbox can be operated between a neutral position and at least one drive position by operating a gear shift (22) between a corresponding neutral position (N) and at least one corresponding drive position (D) , characterized by the steps of detecting an actuation of the gear shift (22) , and of activating the disengagement arrangement (12) in the event of such a detection. 5. The method as claimed in claim 4, characterized in that the gearbox (11) is operated so as to go into a drive position when the speed of rotation of associated running wheels is sufficiently low.

Inventors: HEDMAN ANDERS, HEDMAN, ANDERS
Applicants: HEDMAN ANDERS, VOLVO LASTVAGNAR AB, HEDMAN, ANDERS
Application year: 2001
Main classification: B60K41
IPC codes: B60W10, B60W30, F16D48, F16H59, F16H63