WO2003039903A1

WO2003039903A1 - Apparatus and method preventing start of a vehicle in too high a gear

Info

Publication number: WO2003039903A1
Application number: PCT/SE2002/001973
Authority: WO
Inventors: Bo Warmenius
Original assignee: Scania Cv Ab (Publ)
Priority date: 2001-11-05
Filing date: 2002-10-31
Publication date: 2003-05-15
Also published as: SE518530C2; SE0103656D0; SE0103656L; DE10297417T5

Abstract

The present invention relates to an arrangement and a method for preventing a vehicle being set in motion in too high a gear. The vehicle incorporates an engine (1) with an acceleration control (11) for regulating the engine’s power, a gearbox (5) with a gear control (12) for initiating the engagement of a desired gear in the gearbox (5), and a clutch (3) which is arranged in a connection between the engine (1) and the gearbox (5). The arrangement incorporates a control unit (15) which is designed to receive information concerning the vehicle’s speed, the position of the clutch and the gear engaged in the gearbox (5) and to initiate limitation of the engine’s power in situations where the vehicle’s speed is not over a specified speed level, the clutch (3) is in an unconnected position and a gear which is not acceptable for setting the vehicle in motion is engaged in the gearbox (5).

Description

Apparatus and method preventing start of a vehicle in too high a gear

BACKGROUND TO THE INVENTION, AND STATE OF THE ART

The invention relates to an arrangement and a method for preventing a vehicle being set in motion in too high a gear, according to the preambles of claims 1 and 8.

Being set in motion means here the opening stage of a vehicle's acceleration from a substantially standstill situation. A problem of heavy vehicles with manually operated gears is that certain drivers choose, for reasons of convenience, to engage too high a gear when setting the vehicle in motion. Being set in motion in too high a gear leads, particularly on heavy vehicles which are heavily laden, to considerable wear of the vehicle's clutch. The replacement of worn clutches and the loss of revenue during the time when a working vehicle cannot be used represent a relatively large cost.

SUMMARY OF THE INVENTION

The object of the present invention is to provide an arrangement and a method which make it substantially impossible or at least substantially difficult for a vehicle of the kind mentioned in the introduction to be set in motion in too high a gear and which thus prevent or at least substantially reduce the risk of unnecessary wear of the vehicle's clutch.

The objects stated above are achieved with the arrangement mentioned in the introduction which is characterised by what is indicated in the characterising part of claim 1. For the control unit to limit the power delivered by the engine thus requires that the vehicle be substantially at a standstill, that the clutch be in an unconnected position and that a gear which is not acceptable for setting the vehicle in motion has been engaged in the gearbox. If all of these conditions are fulfilled, the control unit will appropriately limit the engine's power irrespective of the acceleration control position adopted by the driver. The engine power will be limited to such a low value that the vehicle cannot normally be set in motion in the gear engaged. The control unit is preferably a computer which incorporates suitable software for receiving said information and for initiating such limitation of the engine's power. All heavy vehicles incorporate by law some kind of speed limiting device intended to limit the vehicle's maximum speed. Such speed limiting devices usually limit the engine's power by reducing the fuel supply to the engine. The control unit may with advantage utilise the vehicle's existing speed limiting device in order to limit the engine's power to a level which is low enough to prevent the vehicle being set in motion in normal circumstances. A driver using a vehicle equipped with an arrangement according to the present invention will therefore learn not to try to set the vehicle in motion in too high a gear. The damaging practice of setting vehicles in motion in gears which are too high will thus be effectively prevented and the driver will learn to select a correct gear for setting the vehicle in motion. Unnecessary wear of the vehicle's clutch, leading to considerably shortening of clutch service life, will thus be prevented.

According to a preferred embodiment ofthe invention, said speed level is 4 km/h. As limitation of the vehicle's speed is only intended when the vehicle is being set in motion, it is appropriate to define a maximum speed level from which the vehicle may be designated to be set in motion. Such a speed level is preferably about 3 to 4 km/h. The control unit is preferably designed to limit the engine's power at the time of setting the vehicle in motion with respect to all existing gears intended for forward motion other than the gear which has the lowest transmission ratio. Engine power guaranteed to allow the vehicle to be set in motion is thus only available when the vehicle is set in motion in the very lowest gear.

According to another preferred embodiment of the present invention, the control unit is designed to limit the engine's power to the engine's idling power. The control unit thus limits the engine power to the engine's idling power whatever the accelerator control position. In certain situations it will nevertheless be possible to set the vehicle in motion by means of the idling power, e.g. when the vehicle is totally unladen or on a downhill gradient. Setting the vehicle in motion in such circumstances involves no appreciable clutch wear.

According to another preferred embodiment ofthe present invention, the arrangement incorporates a first sensor intended to detect the vehicle's speed. Such a speed-detecting first sensor may for example detect the rotation speed of a suitable component of the vehicle's driveline. The first sensor is designed to send to the control unit a signal concerning the magnitude of the vehicle's speed. Any existing speed-detecting equipment of the vehicle may possibly be used. When the control unit receives information about the prevailing speed, it determines whether the prevailing speed exceeds the intended speed level or not. If the prevailing speed exceeds said level, the speed is too high for it to be possible for subsequent acceleration to be interpreted as the vehicle being set in motion, in which case the control unit does not initiate any limitation of the engine power. The arrangement may incorporate a second sensor designed to detect whether an acceptable gear for setting the vehicle in motion is engaged in the gearbox. Such a second sensor may be of relatively simple design and incorporate a circuit-breaker which is so positioned as to be activated by the gear lever or by a suitable movable part within the gearbox when an acceptable gear is engaged. Such a breaker then sends a signal to the control unit to the effect that an acceptable gear for setting the vehicle in motion is engaged in the gearbox. If such a signal is received, the control unit does not initiate any engine power limitation. If on the contrary no such signal is received, then either no gear has been engaged in the gearbox or a gear which is unacceptable for setting the vehicle in motion has been engaged in the gearbox. Alternatively, any existing sensor which detects the gear lever position may possibly be used for enabling the vehicle to change gear. Finally, the arrangement may incorporate a third sensor designed to detect the position of the clutch. In cases where a clutch pedal is used for operating the clutch, the sensor may incorporate a breaker which is activated when the clutch pedal is in its fully released position corresponding to the fully applied position of the clutch. Such a breaker then sends a signal to the control unit when the clutch is in its fully applied position. If no such signal is received, the clutch is in a more or less unconnected position, which is one of the requirements for the control unit to limit the engine power.

The invention also relates to a method for enabling limitation of the power delivered by an engine for operation of a vehicle of the kind mentioned in the introduction. The method is characterised by steps according to the characterising part of claim 8. These steps require that the vehicle's speed be so low that subsequent acceleration of the vehicle is definable as setting it in motion, that the clutch be in an at least partly unconnected position and that a gear which is not acceptable for setting the vehicle in motion be engaged in the gearbox. All of these three requirements have thus to be fulfilled in order to define a state in which the vehicle is deemed to be being set in motion in too high a gear. If such a state is defined, the power delivered by the engine will thus be limited to a level such as to prevent any normal setting in motion of the vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below by way of examples with reference to the attached drawing in which:

Fig. 1 depicts schematically a vehicle with an arrangement according to the present invention and Fig. 2 depicts schematically a method according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

Fig. 1 schematically depicts selected parts of a vehicle. The vehicle is powered by an engine 1 which may be a combustion engine such as a diesel engine. The engine 1 drives, via an output shaft 2 and a clutch 3, an input shaft 4 to a stepped gearbox 5. The gearbox 5 incorporates a number of shafts with a varying transmission ratio. The gearbox 5 has an output shaft 6 extending from it which engages with a final portion of the vehicle's driveline. The final portion of the driveline incorporates a universal shaft 7, a final gear 8 and driveshafts 9 which are connected to the vehicle's powered wheels 10.

The vehicle incorporates a number of controls by means by which the driver operates the vehicle. For the initiation of a desired engine power, the engine 1 is connected to an acceleration control in the form of an accelerator pedal 11. For the initiation of the engagement of a desired gear in the gearbox 5, the gearbox 5 is connected to a gear control in the form of a gear lever 12. The clutch 3 is manoeuvrable by means of a clutch pedal 13 between a fully applied position in which it creates a substantially rigid connection between the engine 1 and the gearbox 5, and an unconnected position in which it allows at least partial disconnection of the engine 1 from the gearbox 5. A first sensor 14 is designed to detect a parameter which is related to the vehicle's speed. The first sensor 14 detects in the embodiment depicted the speed of the gearbox output shaft 6. The first sensor 14 sends to a control unit 15 a signal concerning the rotation speed of the shaft 6, which is thus related to the vehicle's speed. The sensor 14 is preferably incorporated in the vehicle's normal speed detection equipment. The control unit 15 incorporates a computer with suitable software for receiving information from a number of sensors and for initiating a limited engine power when the vehicle is deemed to be being set in motion with an unacceptable gear engaged in the gearbox 5. The control unit 15 also incorporates stored information concerning a predetermined speed level which represents an upper limit from which any subsequent acceleration of the vehicle is definable as the latter being set in motion. Such a speed level is preferably 3 to 4 km/h. The control unit 15 is designed to receive information concerning the vehicle's prevailing speed frequently enough to enable it to determine substantially continuously whether the prevailing speed exceeds the specified speed level. A second sensor 16 is designed to detect the position of the clutch 3. Such a second sensor 16 may be of relatively simple design and incorporate a breaker which is activated when the clutch pedal 13 is in its fully released position. When the clutch pedal 13 is in its fully released position, the second sensor 16 sends to the control unit 15 a signal to the effect that the clutch 3 is in a fully applied position. The clutch 3 thus creates a rigid connection between the engine 1 and the gearbox 5. A third sensor 17 is designed to detect whether an acceptable gear is engaged in the gearbox 5. The third sensor 17 may also be of relatively simple design and incorporate a breaker which is so positioned as to be activated by a gear lever 12 or by a suitable movable part in the gearbox 5, such as a gearshift bar, when an acceptable gear is engaged. Such a breaker then sends a signal to the control unit 15 when an acceptable gear for setting the vehicle in motion is engaged in the gearbox. A fourth sensor 18 is designed to detect the position of the accelerator pedal 11. A signal with information about the position of the accelerator pedal 11 is sent substantially continuously to the control unit 15. During normal operation of the vehicle, the control unit 15 thus initiates the provision to the engine 1 of a fuel supply which is related to the position of the accelerator pedal 11.

When wishing to set the vehicle in motion, the driver depresses the clutch pedal 13. The clutch 3 disconnects the engine 1 from the driveline, followed by the engine 1 being started up. Thereafter the driver uses the gear lever 12 to engage a desired gear in the gearbox 5. The control unit 15 receives information from the first sensor 14 about the vehicle's prevailing speed. The control unit 15 compares the prevailing vehicle speed with a reference value concerning the stored speed level, which in this case is 4 km/h. The control unit 15 determines that the prevailing vehicle speed is not greater than the stored speed level. The control unit 15 also receives information by means of a signal from the second sensor 16 if the clutch pedal 13 is in its fully released position. If no such signal is received, the control unit finds that the clutch is in an unconnected position. Finally, the control unit 15 receives information by means of a signal from the third sensor 17 if an acceptable gear for setting the vehicle in motion is engaged. If no such signal is received, the control unit 15 finds that no acceptable gear for setting the vehicle in motion has been engaged in the gearbox 5.

If the vehicle's speed is below 4 km/h and the clutch pedal 13 is in an unconnected position and a gear is engaged in the gearbox 5, the control unit 15 will find that this is a situation of setting the vehicle in motion. If the driver has engaged a gear which is acceptable for setting the vehicle in motion, which in most cases will be a reverse gear or the lowest gear for forward motion of the vehicle, the third sensor 17 sends a signal to the control unit 15. The control unit 15 is thus informed that an acceptable gear for setting the vehicle in motion has been engaged in the gearbox 5, and signals received from the fourth sensor 18 concerning the position of the accelerator pedal 11 are transmitted in a conventional manner to a fuel control means, here exemplified by a fuel pump 19, for the supply to the engine 1 of a quantity of fuel which corresponds to the position of the accelerator pedal 11. In this case the process of setting the vehicle in motion will be entirely conventional. If on the contrary the driver has engaged a gear which is not acceptable for setting the vehicle in motion, the control unit 15 receives no signal from the third sensor 17 to the effect that an acceptable gear has been engaged. The vehicle's speed being below 4 km/h, the clutch pedal 13 being in an unconnected position and no acceptable gear having been engaged in the gearbox 5 constitute fulfilment of all the requirements for the control unit 15 to find that the situation is an attempt to set the vehicle in motion in an unacceptable gear. Signals received by the control unit 15 from the fourth sensor 18 concerning the position of the accelerator pedal 11 will then be disregarded and the control unit 15 will limit the amount of fuel delivered by the fuel pump 19 to a value which corresponds to the idling speed of the engine 1. When the driver releases the clutch pedal 13 to set the vehicle in motion, the idling power of the engine 1 is in most situations insufficient for setting the vehicle in motion, or at least so low that the vehicle can in practice not be set in motion in a manner acceptable to the driver. A driver aware that the vehicle is equipped with an arrangement as above will of course avoid engaging too high a gear when attempting to set the vehicle in motion. Attempts to set vehicles in motion in too high gears are thus effectively prevented. Preventing vehicles being set in motion in too high gears eliminates unnecessary clutch wear which would otherwise cause unnecessary shortening of clutch service life.

Fig. 2 depicts a schematic flowchart of a method according to the present invention. The method applies to setting a vehicle in motion and begins with step a, which receives information concerning the vehicle's speed and determines whether the vehicle's speed is not over a specified speed level. The speed level is selected to be so low that any subsequent acceleration of the vehicle is definable as setting the vehicle in motion. In the embodiment depicted, the speed level is set at 4 km/h. If the vehicle's speed is over 4 km/h, no limitation of engine power is applied and the process illustrated in the flowchart starts again. If the vehicle's speed is not over 4 km/h, the process continues. The method's next step b receives information concerning the position of the clutch and determines whether the clutch 3 is in an unconnected position. If the clutch is in a fully applied position, no limitation of engine power is effected and the process starts again. If on the contrary the clutch is in a neutral position, it may be found that the situation may be a setting in motion of the vehicle and the process will continue. The method proceeds thereafter with step c which receives information about the gear engaged in the gearbox and determines whether a gear acceptable for setting the vehicle in motion is engaged in the gearbox 5. If such is the case, there will of course be no limitation of engine power and the vehicle will be allowed to be set in motion conventionally with power applied according to the position of the accelerator pedal 11. If on the contrary an unacceptable gear has been engaged in the gearbox 5, all the criteria for the situation of an attempt to set the vehicle in motion in an unacceptable gear are fulfilled. The result in this case at step dis a limitation of the engine power and the speed of the engine 1 will remain at idling speed whatever the position of the accelerator pedal. 11. The engine power will thus be limited to the idling power. In most situations it is impossible to set the vehicle in motion by means of the idling power, although this may be possible with a vehicle which is unladen or on a downhill gradient. For engine power limitation to be possible, the determinations referred to above concerning the vehicle's speed, the position of the clutch and the gear engaged in the gearbox must be ascertainable substantially simultaneously.

The invention is in no way limited to the embodiment described but may be varied freely within the scopes of the claims. Fig. 1 depicts an accelerator pedal 11 whose position is transmitted by electrical signals from a sensor 18 to an electrically controlled fuel pump 19 or similar fuel injection means, via the control unit 15. In this case the control unit 15 can easily limit the engine power by a suitable control signal to the fuel pump 19. The invention is also applicable in vehicles in which the accelerator pedal is connected mechanically to a fuel pump. In such cases the control unit 15 may, for example, act upon the compressed air cylinders incorporated in the existing speed limiters of many vehicles so that the compression cylinders are controlled so that the engine is supplied with a quantity of fuel such as to provide only idling power if the vehicle is set in motion in too high a gear. The sequence of the three different stages a-c in Fig. 2 may substantially be varied as desired. What is essential is that the three different factors be fulfilled at substantially the same time. In the embodiment described, the engine power is limited to what corresponds to idling power, but in other embodiments of the invention the power may be limited to other levels, although nevertheless to such low levels as in practice not to allow the vehicle to be set in motion in the gear concerned. In alternative embodiments, more than one gear may be also deemed acceptable for setting the vehicle in motion, in which case setting in motion takes place with no engine power reduction when any of these gears is selected.

Claims

1. An arrangement for preventing a vehicle from being set in motion in too high a gear, which vehicle incorporates an engine (1) which is connected to an acceleration control (11) for regulating the engine's power, a gearbox (5) which is connected to a gear control (12) for initiating the engagement of a desired gear in the gearbox (5), and a clutch (3) which in a fully applied position is designed to create a substantially rigid connection between the engine (1) and the gearbox (5) and in an unconnected position allows relative movements between the engine (1) and the gearbox (5), characterised in that the arrangement incorporates a control unit (15) which is designed to receive information concerning the vehicle's speed, the position of the clutch and the gear engaged in the gearbox (5) and to initiate limitation of the power ofthe engine (1) when the vehicle's speed is not over a specified speed level, the clutch (3) is in an unconnected position and a gear which is not acceptable for setting the vehicle in motion is engaged in the gearbox (5).

2. An arrangement according to claim 1, characterised in that said speed level is 4 km/h.

3. An arrangement according to claim 1 or 2, characterised in that the control unit (15) is designed to limit the engine's power with respect to all existing gears intended for forward motion other than the gear which has the lowest transmission ratio.

4. An arrangement according to any one of the foregoing claims, characterised in that the control unit (15) is designed to limit the engine's power to the engine's idling power.

5. An arrangement according to any one of the foregoing claims, characterised in that a first sensor (14) is designed to detect a parameter which is related to the vehicle's speed.

6. An arrangement according to any one of the foregoing claims, characterised in that a second sensor (17) is designed to detect whether an acceptable gear for setting the vehicle in motion is engaged in the gearbox (15).

7. An arrangement according to any one of the foregoing claims, characterised in that a third sensor (16) is designed to detect the position of the clutch.

8. A method for preventing a vehicle from being set in motion in too high a gear, which 5 vehicle incorporates an engine (1) which is connected to an acceleration control (11) for regulating the engine's power, a gearbox (5) which is connected to a gear control (12) for initiating the engagement of a desired gear in the gearbox (5), and a clutch (3) which in a fully applied position is designed to create a substantially rigid connection between the engine (1) and the gearbox (5) and in an unconnected position allows relative movements 10 between the engine (1) and the gearbox (5), characterised in that the method comprises the following steps: a) determining whether the vehicle's speed is not over a specified speed level, b) determining whether the clutch (3) is in an unconnected position, c) determining whether a gear which is not acceptable for setting the vehicle in motion 15 is engaged in the gearbox (5) and d) limiting the engine's power if the determinations indicated above are fulfilled.

9. A method according to claim 8, characterised in that it limits the engine's power if the vehicle's speed is not over 4 km/h.

20

10. A method according to claim 8 or 9, characterised in that it limits the engine's power with respect to all existing gears intended for forward motion other than the gear which has the lowest transmission ratio.

25 11. A method according to any one of the foregoing claims 8-10, characterised in that it limits the engine's power to the engine's idling power.