GB2354297A

GB2354297A - A transmission system with a controller which allows push or tow starting of engine

Info

Publication number: GB2354297A
Application number: GB0019938A
Authority: GB
Inventors: Robin John Warren
Original assignee: LuK Lamellen und Kupplungsbau GmbH
Current assignee: LuK Lamellen und Kupplungsbau GmbH
Priority date: 1999-08-31
Filing date: 2000-08-15
Publication date: 2001-03-21
Anticipated expiration: 2020-08-15
Also published as: DE10037544A1; GB0019938D0; GB2354297B

Abstract

A transmission system comprises a multi ratio gearbox 12 with a gear engaging mechanism 25 and a main drive clutch 14 having clutch actuating means 38, 22, 20. The mechanism 25 and the clutch actuating means are controlled by an electronic controller 36. If an engine 10 will not start a sensor 26, after an ignition switch 54 has been turned on, provides a signal to the controller 36 to confirm that the engine 10 is stationary, the engine 10 may then be push/tow started. With gear lever 24 in neutral the vehicle is pushed/towed to a speed V, indicated by sensor 26, in excess of a minimum threshold value V<SB>min</SB> the gear lever is then moved to drive mode whereupon the controller 36 actuates the mechanism 25 to select a gear appropriate to the vehicle speed V and actuates the actuating means to engage the clutch 14. Upon starting the engine 10, or if the engine fails to start, the clutch 14 is disengaged by moving gear lever 24 back to the neutral position.

Description

2354297 AUTOMATED TRANSMISSION SYSTEMS The present invention relates to

automated transmission systems and in particular to fully or semi-automated transmission systems having a clutch, such as a main drive clutch, clutch actuation means, such as an actuator, 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 and a driver-operable drive mode selector allowing a driver to select neutral or a drive mode.

With transmission systems of this type, when starting the vehicle from rest, the clutch is disengaged and a take-up gear selected automatically.

The clutch is then re-engaged as the engine speed increases due to actuation of the accelerator or of the throttle valve, to take-up drive, so that the vehicle may be driven away.

Hitherto with systems of this type, clutch re-engagement is controlled so that the engine speed follows a reference speed, in order to assure a smooth take-up of drive, for example as disclosed in EP0038113; EP0696341 or EP0735957 to the disclosure of which explicit reference is made and whose content is expressly incorporated in the disclosure content of the present application.

With transmission systems of this type, a push or tow start is only possible with difficulty or not at all as re-engagement of the clutch depends on the engine speed.

The purpose of the invention is to provide a system as above, which at least reduces the disadvantages of the state of the prior art.

The present invention provides an automated transmission system with a push or tow start facility.

According to one aspect of the present invention, an automated transmission system comprises a clutch, such as a main drive clutch, clutch actuation means for controlling 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 including means for sensing the state of an ignition circuit of an engine connected to the gearbox via the clutch, means for sensing rotation of the engine, means for sensing the vehicle speed and generating a signal variable with the vehicle speed and means for sensing the position of the drive mode selector; said control means being adapted to cause the gear engaging mechanism to engage a gear ratio which is appropriate for the speed of the vehicle and to cause the clutch actuation means to re-engage the clutch, when the drive mode selector is moved from neutral to a forward drive mode, while the ignition is on, the engine stationary and the vehicle speed above a threshold value.

With the transmission system described above, if the vehicle will not start, due for example to malfunction of the starter motor or starter circuit, it is possible to push start or tow start the engine, by pushing or towing the vehicle at a speed above the threshold value, while the ignition is on and then moving the drive mode selector from a neutral position to a forward drive mode position, to drivingly engage the engine.

The clutch may be disengaged regardless of whether the engine has started or not, by movement of the drive mode selector back to neutral.

Such action will also cause control means to disengage the selected gear.

According to a preferred embodiment of the invention, upon movement of the drive mode selector from neutral to a forward drive mode in accordance with the present invention, the clutch will be re-engaged following a pre-determined profile which will ensure smooth engagement.

If while the vehicle is in motion, the drive mode selector is moved from neutral to a reverse drive mode, the control means will hold the transmission in neutral.

The push/tow start feature of the present invention is preferably inhibited, if faults are detected in any of the components/circuits critical to operation thereof, for example:

the ignition switch circuit; shift lever position switch circuit; gear shift and select actuators; clutch actuators; control and position measurement circuits; or road speed measurement circuits.

Such faults may be recorded on a fault log associated with the control means of the transmission system.

The present invention relates to fully automated transmission systems in which gear changing is under automatic control of the control means or to semi-automated transmission systems in which after take-up from rest, gear changing may be controlled by the driver of the vehicle.

Preferable, in the case of semi-automated or fully automated transmission systems the take-up gear is selected after moving the driver-operated lever. In fully automated transmissions the gear may be selected automatically by a control unit, so that no intervention by the driver is needed to select the gear at least in one operating mode. In shift transmission systems with an automatic clutch, however, the take-up -4 gear is selected manually by moving the driver-operated lever.

An embodiment of the invention is now described with reference to the accompanying drawings, in which:

Figure 1 shows a schematic view of a semi-automated transmission system in accordance with the present invention; and Figure 2 shows a typical profile for clutch re-engagement in accordance with the present invention.

Figure 1 of the accompanying drawings 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 51 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 to the disclosure of which explicit reference is made and whose content is expressly incorporated in the disclosure content of the present application.

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 to the disclosure of which explicit reference is made and whose content is expressly incorporated in the disclosure content of the present application.

In addition to the above mentioned sensors, control unit 36 also receives signals from a vehicle speed sensor 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. 15 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 reverse 20 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 25 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 EP003811 3; EP0696341 or EP0735957 to the disclosure of which explicit reference is made and whose content is expressly incorporated in the disclosure content of the present application, in order to ensure a smooth take-up of drive.

If the engine 10 will not start, due for example to a fault in the starter motor or starter circuit 1 Oa, the engine 10 may be tow started in the following manner:

a. the ignition switch 54 is actuated to turn on the engine ignition and also key-on the transmission system, so that the control unit 36 will disengage the clutch 14; actuation of the ignition switch 54 also provides a signal to the control unit 36, confirming that the ignition is on; b. sensor 26 provides a signal to control unit 36 to confirm that the engine is stationary; C. with the gear lever 24 in the neutral "N" position the vehicle may then be towed to a speed V in excess of a minimum threshold value VMin, typically 8kph, the vehicle speed V being indicated by sensor 52; d. the gear lever 24 is then moved from the neutral "N" position to drive mode "S", whereupon the control unit 36 actuates the gear engaging mechanism 25 to select a gear appropriate to the vehicle speed V and actuates the clutch actuator means 38,22,20 to re engage the clutch 14.

The torque transmitted from the wheels of the vehicle will then turn the engine 10, so that it may be started.

Upon starting of the engine 10, or if the engine 10 fails to start, the clutch 14 may be disengaged by moving the gear lever 24 back from the drive position "S" to the neutral position "N".

Re-engagement of the clutch 14 in the manner described above is controlled by the control unit 36 in accordance with a predefined profile, -8 as illustrated in figure 2, in order to achieve smooth engagement.

As illustrated in figure 2, after gear lever 24 is moved from neutral "N" to drive mode "S" and an appropriate gear has been engaged, the clutch actuator means 38,22,20 under control of control unit 36 initially moves the clutch plates together at a rapid rate, until the clutch plates reach the touch point TP at which torque begins to be transmitted by the clutch 14.

The clutch plates are then moved together at a more gradual rate, until at point T the clutch 14 transmits sufficient torque to drive the engine 10 without slippage, that is when the clutch driven plate speed indicated by sensor 42 is equal to the engine speed indicated by sensor 26.

Upon starting of the engine 10 continued engagement of the clutch 14 may be controlled in known manner in response to increase in engine speed. Alternatively the 'Clutch 14 may be disengaged if the gear lever 24 is moved from drive mode "S" to neutral "N" or if the engine 10 fails to start and the vehicle speed V falls below the threshold value Vmin, The control unit 36 includes a fault log in which codes representative of faults in any of the components or circuits of the transmission system are logged. If there or any faults logged in respect of any of the components/circuits utilised in the tow start facility, then control unit 36 will inhibit the tow start facility.

Various modifications may be made without departing from the invention.

For example while in the above embodiments hydraulic means are used for actuation of the clutch and gear selector 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,to the disclosure of which explicit reference is made and whose content is expressly incorporated in the -9 disclosure content of the present application.

An automated transmission system comprises control means 36 including means for sensing the state of an ignition circuit of an engine 10, a sensor for sensing rotation of the engine 10, a sensor for sensing the vehicle speed and generating a signal variable with the vehicle speed and a sensor for sensing the position of the drive mode selector 24; said control means 36 being designed such that it causes a gear engaging mechanism 25 to engage a gear ratio which is appropriate for the speed of the vehicle, and the clutch actuation means 38,22,20 to re-engage a clutch 14, when the drive mode selector is moved from neutral to a forward drive mode while the ignition is on, the engine is stationary and the vehicle is being pushed or towed with a vehicle speed above a threshold value.

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.

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 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

CLAIMS.

1. An automated transmission system comprising a main drive clutch, clutch actuation means for controlling 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 including means for sensing the state of an ignition circuit of an engine connected to the gearbox via the clutch, means for sensing rotation of the engine, means for sensing the vehicle speed and generating a signal variable with the vehicle speed and means for sensing the position of the drive mode selector; said control means being adapted to cause the gear engaging mechanism to engage a gear ratio which is appropriate for the speed of the vehicle and to cause the clutch actuation means to re-engage the clutch, when the drive mode selector is moved from neutral to a forward drive mode, while the ignition is on, the engine stationary and the vehicle speed above a threshold value.

2. An automated transmission system according to claim 1 in which upon movement of the gear selector from neutral to a forward drive mode the control means is adapted to cause the clutch to be re-engaged following a pre-determined profile.

3. An automated transmission system according to claim 2 in which upon movement of the gear selector from neutral to a forward drive mode the control means is adapted to causes the clutch initially to re-engage at a rapid rate, until the clutch begins to transmit torque, at which point re engagement proceeds at a more gentle rate.

4. An automated transmission system according to any one of the preceding claims in which the control means is adapted to re-engage the clutch to a point at which it will transmit sufficient torque to drive the engine without slippage.

5. An automated transmission system according to any one of the preceding claims in which the control means is adapted to disengage the clutch upon movement of the drive mode selector from a forward drive mode to neutral.

6. An automated transmission system according to any one of the preceding claims in which the control means is adapted to disengage the clutch if the vehicle speed falls below the threshold value.

7. An automated transmission system according to any one of the preceding claims in which the vehicle speed threshold value is of the order of 8kph.

8. An automated transmission system according to any one of the preceding claims in which a fault log is associated with the control means, fault codes in respect of components and circuits relating to operation of the transmission system being stored in the fault log if a fault occurs in a particular component or circuit, the control means being adapted to inhibit re-engagement of the clutch upon movement of the drive mode selector from neutral to a forward drive mode, if a fault code relevant to a critical component or circuit is present in the fault log.

9. An automated transmission system substantially as described herein with reference to, and as shown in, figures 1 and 2 of the accompanying drawings.