GB2355502A - Transmission controller that automatically disengages a selected gear if a vehicle does not move away - Google Patents

Abstract

A semi-automatic transmission, for a vehicle, comprises a multi-ratio gearbox 12 and a gear engaging mechanism 25 controlled by electronic control means 36. When a gear selector lever 24 is moved from its neutral position N to its drive position S the controller 36 automatically selects a take-up from rest gear, eg first gear, and when accelerator pedal 19 is depressed clutch 14 is engaged and the vehicle moves away from rest. If after a predetermined period, eg 10 seconds, the accelerator 19 is not depressed the controller 36 sounds a warning, eg a buzzer after 7 seconds, automatically disengages the take-up gear and returns the gearbox to neutral. The controller 36 will inhibit disengagement of the take-up gear if a brake 58 is depressed. When the brake 58 is released the above procedure is repeated. In order to re-initiate take-up on starting the gear lever 24 must be returned to the neutral position N. Disengaging the take-up gear prevents a forgetful driver overlooking that a gear is engaged.

Description

2355502 TRANSMISSION SYSTEMS The present invention relates to an automated

or a semi-automated transmission system; said transmission systems having a clutch, for example a main drive clutch, clutch actuation means for controlling the state of engagement of the clutch, a gearbox, for example a multi-ratio gearbox, a gear engaging mechanism for engaging an operative ratio of the gearbox, and a driver-operable drive mode selector allowing a driver to select neutral or a drive mode or gear.

With transmission systems of this type, at take-up from rest, the clutch is disengaged and a take-up gear is selected automatically. The clutch is then engaged as the vehicle throttle is actuated. A transmission system of this type is disclosed in UK Patent No 2302377 the disclosure of which is incorporated herein by reference thereto and whose disclosure content is expressly incorporated in that of the present application.

Typically with such transmission systems, upon starting of the engine the transmission system is activated, for example keyed-on, and the clutch automatically disengaged. Movement of the drive mode selector from neutral to a drive mode, for example "drive" or "reverse", will cause a take-up gear to be automatically selected.

The automatic selection of a take-up gear in this manner presents the problem that if the driver does not, in the short term, take subsequent action to drive away or to abort the take-up procedure by returning the drive mode selector to neutral, he may forget that the transmission is in gear and inadvertently depress the accelerator pedal, causing the vehicle to move when he is not expecting it to do so. The driver could moreover leave the driving seat after engaging a drive mode and possibly be replaced by another driver who is not aware of the state of the -2 transmission system.

A gear indicator is normally provided to indicate the gear engaged, but this may be overlooked.

The purpose of the present invention is to improve a transmission system of the above kind in such a way that the safety-critical situations will be avoided or at least rendered less acute. According to the present application this is achieved by the means described in claim 1.

Advantageous further developments are described in the subordinate claims.

According to one aspect of the present invention a vehicle transmission system or transmission comprises a clutch, for example a main drive clutch, clutch actuation means for controlling the state of engagement of the clutch, a multi-ratio gearbox, a gear engaging mechanism for engaging an operative ratio of the gearbox, a driver-operable drive mode selector allowing the driver to select neutral or a drive mode and an electronic control means to control the clutch actuation means and gear engagement mechanism, the control means initiating take-up from rest upon movement of the drive mode selector from neutral to a drive mode, the control means being adapted to disengage the clutch and, upon initiation of take up from rest, automatically select a take-up gear, the control means automatically disengaging the automatically selected take-up gear, if the vehicle does not move away within a predetermined time period from initiation of take-up from rest.

In accordance with the present invention, if the vehicle does not move within a predetermined time period (typically about 10 seconds) of initiating take-up from rest, the take-up gear is disengaged, thus removing the risk that the vehicle will be inadvertently caused to move.

According to a preferred embodiment of the invention, an audible and/or visual warning may be provided before the end of the predetermined time period, for example 7 seconds after initiation of take-up from rest, to remind the driver that the take-up gear is engaged but that no action has been taken to cause the vehicle to move.

When the take-up gear is automatically disengaged, a further audible and/or visible warning may be given to indicate that the gear box is in neutral while the drive mode selector position indicates that the transmission is in a drive mode. A suitable indication of this state would be to flash a gear indicator display means.

There may of course be circumstances where the driver may not be able to take-up drive within the predetermined period, for example where he is waiting to pull out into traffic. Such situations may be accommodated by inhibiting automatic disengagement of the take-up gear, upon application of the vehicle brake. In such circumstances the predetermined period may be timed from release of the brake or a different predetermined period could be applied from release of the brake.

Where the transmission system has automatically disengaged the automatically selected take-up gear after being timed out, the driver would then have to move the drive mode selector from the a drive mode, back to neutral and back to a drive mode, in order to initiate take-up once again.

Take-up may be initiated by movement of the drive mode selector from neutral to either a forward or reverse drive mode.

An embodiment of the invention is now described, by way of example only, with reference to the accompanying drawing which shows a schematic view of a semi-automatic transmission system in accordance -4 with the present invention.

The accompanying drawing shows an engine 10 with a starter and associated starter circuit 1 Oa which is coupled through the main drive friction clutch 14 to a multi-speed synchromeshed lay shaft-type gearbox 12, via a gearbox input shaft 15. Fuel is supplied to the engine by a throttle 16 which includes a throttle valve 18, operated by accelerator pedal 19. The invention is equally applicable to electronic or mechanical fuel injection petrol or diesel engine.

The clutch 14 is actuated by a release fork 20 which is operated by a hydraulic slave cylinder 22, under the control of a clutch actuator control means 38.

A gear selector lever 24 operates in a gate 50 having two limbs 51 and 52 joined by a cross track 53 extending between the end of limb 52 and intermediate of the ends of limb 51. The gate 50 defines five positions; "R" at the end of limb 52; "N" intermediate of the ends of the cross track 53; "S" at the junction of limb 5 1 with the cross track 53; and " + " and at the extremities of limb 51. In limb 51 the lever 24 is biased to the central "S" position. The "N" position of the selector lever 24 corresponds to neutral; "R" corresponds to selection of reverse gear; "S" corresponds to selection of a forward drive mode; momentary movement of the lever to the " + " position provides a command to cause the gearbox to shift up one gear ratio; and momentary movement of the gear lever 24 to the "-" position provides a command to cause the gearbox to shift down one gear ratio.

The positions of the lever 24 are sensed by a series of sensors, for example micro switches or optical sensors, positioned around the gate 50.

Signals from the sensors are fed to an electronic control unit 36. An output from the control unit 36 controls a gear engaging mechanism 25, which engages the gear ratios of the gearbox 12, in accordance with movement of the selector lever 24 by the vehicle operator. The gear engaging mechanism 25 may, for example, comprise hydraulic rams and solenoid control valves to move selector members to engage and disengage the various gear ratios, for example as disclosed in patent specification W097/0541 0 the disclosure of which is incorporated herein by reference thereto.

In addition to signals from the gear selector lever 24, the control unit 36 receives signals from:

sensor 1 9a indicative of the degree of depression of the accelerator pedal 19; sensor 30 indicative of the degree of opening of the throttle control valve 18; sensor 26 indicative of the engine speed; sensor 42 indicative of the speed of the clutch driven plate; sensor 34 indicative of the clutch slave cylinder position; and sensor 32 indicative of the gear ratio selected.

The control unit 36 utilises the signals from these sensors to control actuation of the clutch 14 during take-up from rest and gear changes, for example as described in patent specifications EP0038113, EP0043660,

EP0059035, EP01 01220 and W092/13208 the disclosures of which are incorporated herein by reference thereto and whose disclosure content is expressly incorporated in that of the present application.

In addition to the above mentioned sensors, control unit 36 also receives signals from an antilock braking system (ABS) sensor system 52, ignition switch 54 and brake switch 56 associated with the main braking system, for example the footbrake 58 of the vehicle.

A buzzer 50 is connected to the control unit 36 to warn/indicate to the vehicle operator as certain operating conditions occur. In addition or in place of the buzzer 50 a flashing warning light or other indicating means may be used. A gear indicator 60 is also provided to indicate the gear ratio selected.

With the system described above, when the vehicle is at rest, starting of the engine 10 by actuation of the ignition switch 54, will key-on the transmission system and the control unit 36 will cause the clutch actuator means 38,22,20 to disengage the clutch 14. Movement of the gear lever 24 from the neutral "N" position to the drive position "S" or rever se position "R" will then cause the control unit 36 to actuate the gear engaging mechanism 25 to engage, respectively, the lowest forward gear ratio (first gear) or reverse gear. Upon depression of the accelerator pedal 19 to drive the vehicle away, the control unit 36 will then cause the clutch actuator means 38,22,20 to re-engage the clutch 14, to take-up the drive. Re-engagement of the clutch 14 in this manner will be controlled by control unit 36, in the manner disclosed, for example, in EP0038113; EP0696341 or EP0735957 the disclosures of which are incorporated herein by reference thereto and whose disclosure content is expressly incorporated in that of the present application, in order to ensure a smooth take-up of drive.

If after 7 seconds have elapsed from initiation of take up, the vehicle has not moved, the buzzer 50 is sounded to warn the driver that the take-up gear is engaged. If after a further 3 seconds the vehicle does not start to move; the driver does not apply the brake 58; or the driver does not abort the take-up from rest procedure; the control unit 36 causes the gear engaging mechanism 25 to automatically disengage the take-up gear and return the gearbox 12 to neutral. Upon disengagement of the take-up gear in this manner the gear indicator 60 is flashed to indicate the discrepancy between the position of gear lever 24, which indicates that the transmission is in the "drive" mode; and the state of the gearbox 12 which is in neutral.

The driver may abort the take-up procedure by; moving the gear lever 26 from the "R" or "S" position back to the "N" position; or by keying-off the transmission system by means of the ignition switch 54.

If the driver applies the vehicle brake 58, either before initiation of the take-up from rest procedure or before 10 seconds have elapsed from initiation of the take-up from rest procedure, automatic disengagement of the take-up gear is inhibited until 10 seconds have elapsed from release of the brake 58, with the take-up gear engaged, if the vehicle has still not moved. The driver may thus maintain the transmission system in the take-up from rest mode for a period of more than 10 seconds, by application of brake 58, when it is his intention to drive away immediately but this is delayed for some reason, for example traffic conditions.

To re-engage a take-up gear after take-up from rest has been automatically aborted in the manner disclosed above, the driver must first return the gear lever 24 to the "N" position and then back to the "S" or "R" position in order the initiate take-up from rest once again.

Various modifications may be made without departing from the present invention. For example while in the above embodiment 10 seconds is allowed for the vehicle to start to move after initiation of start-up from rest, any appropriate period may be selected. Moreover while in the above embodiment an audible warning is given before the take-up gear is 25 disengaged, such a warning is optional.

While in the above embodiment hydraulic means are used for actuation of the clutch and gear engagement mechanism; hydraulic, pneumatic and/or electrical actuators, for example electric motors or solenoids, may be used, for example as disclosed in DE1 9504847; W097/10456 or DE1 9734023, the disclosures of which are incorporated herein by reference thereto and whose disclosure content is expressly incorporated in that of the present application.

The present invention is also applicable to fully automated transmission systems, in which all gear changes are under control of control unit 36 using, for example shift maps corresponding to the ratios of the gearbox 12.

The claims submitted with the application are formulation proposals without prejudice to the attainment of more complete patent protection. The Applicant reserves the right to claim additional combinations of features only disclosed so far in the description and/or the drawings.

Back-references in the subordinate claims relate to further developments of the object of the principal claim by virtue of the features specified in the subordinate claim in each case; they are not to be understood as waivers of the right to self-sufficient, objective protection for the feature combinations of the subordinate claims to which they refer. 20 Since, compared with the state of the art on the priority date, the subordinate claims can constitute individual and independent inventions, the Applicant reserves the right to make use of them as the object of independent claims or distinguishing clarifications. They may also constitute self-sufficient inventions having a design independent of the 25 objects of the preceding subordinate claims.

The example embodiments are not to be understood as limitations of the invention. Rather, within the scope of the present disclosure numerous variants and modifications are possible, in particular such variants, elements and combinations and/or materials which, for example by combination or variation of features, elements or processes described individually in combination with the general description, example embodiments and drawings and the claims, would be accepted by those familiar with the field as a solution of the objectives set and, by combination of such characteristics, would lead to a new object or to new process steps or process step sequences, even so far as they relate to manufacturing, testing and operating processes.

Claims (9)

CLAIMS.

1. A vehicle transmission system comprising a main drive clutch, clutch actuation means for controlling the state of engagement of the clutch, a multi-ratio gearbox, a gear engaging mechanism for engaging an operative ratio of the gearbox, a driver-operable drive mode selector allowing the driver to select neutral or a drive mode and an electronic control means to control the clutch actuation means and gear engagement mechanism, the control means initiating take-up from rest upon movement of the drive mode selector from neutral to a drive mode, the control means being adapted to disengage the clutch and, upon initiation of take up from rest, automatically select a take-up gear, the control means automatically disengaging the automatically selected take-up gear, if the vehicle does not move away within a predetermined time period from initiation of take-up from rest.

2. A vehicle transmission system according to claim 1 in which the predetermined period is of the order of 10 seconds.

3. A vehicle transmission system according to 1 or 2 in which a warning is given before the expiry of the predetermined time period.

4. A vehicle transmission system according to claim 3 in which a warning is given 7 seconds after initiation of take-up from rest if the vehicle has not moved.

5. A vehicle transmission system according to any one of the preceding claims in which automatic disengagement of the take-up gear is inhibited by application of the vehicle brake either before initiation of take up from rest or within the predetermined time period.

6. A vehicle transmission system according to claim 5 in which the takeup gear is automatically disengaged if the vehicle does not move within a predetermined time period of the brake being released.

7. A vehicle transmission system according to any one of the preceding claims in which a warning is given after automatic disengagement of the take-up gear.

8. A vehicle transmission system according to any one of the preceding claims in which the drive mode selector must be moved back to a neutral position and then back to a drive mode in order to re-initiate take-up from rest, after the take-up gear has been automatically disengaged.

9. A vehicle transmission system substantially as described herein with reference to and as shown in the accompanying drawing.