GB2209854A

GB2209854A - Motor vehicle control

Info

Publication number: GB2209854A
Application number: GB8821581A
Authority: GB
Inventors: Ralf M Bartke
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1987-09-16
Filing date: 1988-09-15
Publication date: 1989-05-24
Anticipated expiration: 2008-09-15
Also published as: DE3731109A1; JPS6490834A; GB2209854B; DE3731109C3; DE3731109C2; GB8821581D0

Description

h 2209854+1 METHOD OF AND EQUIPMENT FOR REPORTING A FAULT CONDITION IN A

MOTOR VEHICLE The present invention relates to a method of and equipment for reporting a fault condition in a motor vehicle.

Warning equipment for this purpose is disclosed in DE-OS 35 10 321.

In the case of that equipment, a diagnosed fault in a technical system of the motor vehicle is signalled in such a manner that a certain operat ional state of the motor vehicle outside the travel operation is varied abnormally, i.e. the idling is modulated. A possibility of power limitation is not provided. The vehicle must also pass over into the operational state of idling in order for the driver to have the fault brought to his attention by the idling speed fluctuation. It is described in DEPS-23 01 354, which concerns equipment for the regulation of the fuel-air ratio 'in an internal combustion engine, that a lean mixture is provided on failure of a control sensor in order to relieve a catalytic converter and the environment. A power drop of the engine is connected therewith. Electronic engine control systems are in general known, for example from G. Kolberg: "Elektronische Motorsteuerung fUr Kraftfahr20 zeuge", Motortechnische Zeitschrift, Stuttgart, 4, 1985. There exists a need for a method of transmitting a clear fault condition report to a vehicle driver, such as to oblige the driver to immediately seek remedial action. According to the present invention there is provided a method of reporting a fault condition in a motor vehicle with an engine controllable in power by the driver of the vehicle, the method comprising the step of modifying a given usual relationship between actual value of - 2 generated or delivered engine power and driver-selected target value of engine power in response to recognition of a fault in a system of the vehicle, the relationship being modified in recognisable manner in at least one range above a target value for engine idling speed.

According to a second aspect of the present invention there is provided equipment for reporting a fault condition in a motor vehicle with an engine controllable in power by the driver of the vehicle, the equipment comprising means to modify a given usual relationship between actual value of generated or delivered engine power and driverselected target value of engine power in response to recognition of a fault in a system of the vehicle, the relationship being modified in recognisable manner in at least one range above a target value for engine idling speed.

A method and equipment embodying the invention may have the advant- age that, on the occurrence of a fault, a fault report takes place through disturbance of the normal operation or travel behaviour of the vehicle, so that the defect does not remain unnoticed. The driver is thus obliged to look for a workshop, but the vehicle can still reach such a workshop under own power. The method is thus particularly suit- able for reporting faults which would otherwise eventually entail complete failure of the vehicle. In advantageous manner, the warning method can be used for emergency travel operation of the motor vehicle, in particular, in the case of failure of or a defect in the exhaust system.

In a preferred example of the method, the relationship is modified in at least part of a range of driver-selectable target v.alues for engine power. For preference, the relationship is so modified as to 1 provide a reduction, for example by substantially 30 percent, in actual value in relation to driver-selected target value in said part of the range of selectable target values. In particular, the relationship can be so modified that the actual value is unchanged by change in the driverselected target value within said part of the range.

The method may also include the preliminary step of driver selection of the target value for engine power by way of an accelerator pedal. In that case, the relationship can be modified by causing travel of the accelerator pedal to be ineffective for variation of the driver selectable target value within a range of such travel. Expediently, said range of travel is substantially 75 percent of the total effective pedal travel starting from rest.

A warning indication can also be provided simultaneously with the step of modifying, the warning indication being, for example, at 15 least one of an optical signal and an acoustic signal.

An example of the method and an embodiment of the equipment will now be more particularly described by way of example only, with refer- ence to the accompanying drawings, in which:

Fig. 1 is a schematic diagram of basic components for use in performance of a method embodying the invention; Fig. 2 is a block schematic diagram of the steps in performing such a method; and Fig. 3 is a diagram showing the relationship of actual value and target value of engine power in performance of the method.

Referring now to the drawings, there is shown equipment associated with a motor vehicle having an internal combustion engine 13. A power - 4 target value generator for the drive energy, in the form of an accelerator pedal 10, is provided for the driver. The mechanical target value (angle-C) is converted by way of a setting resistor 10a into an electrical signal. This signal is fed to electrical regulating equipment 11, which can also detect further parameters such as engine temperature, additional loads, engine rotational speed N and so forth, by way of signal inputs 15.

The regulating equipment 11 provides a control signal for an electrical drive 12, which operates a throttle flap 12a, of the engine 13. Such an arrangement is known from Kolberg op. cit.

The engine control system also comprises a device or diagnostic circuit 11b which, through monitoring, can recognise at least one fault in the technical system of the motor vehicle and/or can receive a fault signal supplied by way of external inputs. In the illustrated embodiment, this device, in the event of a fault, provides an optical signal 14 and/or acoustic signal for the driver. The signal may, however, be omitted. In the method exemplifying and equipment embodying the present invention, however, this device changes the characteristic between preset target value and engine power in significant manner.

The course of such a method is illustrated in Fig. 2. The target value generator 10 is mechanically connected with the setting resistor 10a, which converts the mechanical target value into an electrical one in the form of a voltage. The target value can be fed by way of two switching paths 17 and 18, with respective regulating programs 20 and 21, to the drive 12 of the throttle flap 12a. The diagnosis circuit arrangement 11b functions as described above. In the normal case, i.e. when no fault is present, the circuit 11b with a fault condition I- - 5 recognition stage 11c frees the path 18 to normal regulation (program 21), which by way of the drive 12 actuates the throttle flap 12a. When a fault is ascertained, then instead of the path 18, the path 17 is freed to a modified regulation or control (program 20), which also causes the drive 12 to actuate the throttle flap 12a.

The regulation or control, thus modified, acts in the preferred example of embodiment in the manner shown in Fig. 3, which illustrates engine power (%) plotted against accelerator pedal angle (-C). In place of the relationship desired in the normal case between target value and effect (actual value) at the engine, an idle travel is now present at the start of the target value generator, this idle travel comprising about 75% of the total possible travel and preventing any kind of reaction of the engine. Following thereupon, as far as the end of the travel of the target value generator, there is an approximately linear relationship between the generator angle and engine power, wherein the engine power delivery reaches a maximum of about 30% of the normally possible maximum.

Other power curves are, of course, feasible. For example the idle travel can adjoin the end of the linear part, which then lies 20 at the start, or the curve can be generally step-shaped.

In addition, equipment embodying the invention can be used to provide emergency travel control, for example when the main target value regulation has failed because of a defect. In every case, the driver has his attention drawn to the fault and is obliged to look 25 for a workshop.

The method is equally applicable to motor vehicles with other drive systems, for example, electrical motors. Moreover, the method 1 is not restricted to a target value generator in the form of an accelerator pedal, but is equally applicable to generators of other types, for example a twist grip in the case of two-wheel and three-wheel vehicles, conversion of the target value into an electrical signal also not being necessary. In place of regulation by two paths, it is, of course, also possible to so modify the normal regulation in the fault case so that the same effect results for the driver.

-C

Claims

A method of reporting a fault condition in a motor vehicle with an engine controllable in power by the driver of the vehicle, the method comprising the step of modifying a given usual relationship between actual value of generated or delivered engine power and driver-selected target value of engine power in response to recognition of a fault in a system of the vehicle, the relationship being modified in recognisable manner in at least one range above a target value for engine idling speed.
2. A method as claimed in claim 1, wherein the engine is an internal combustion engine.
3. A method as claimed in either claim 1 or claim 2, wherein the relationship is modified in at least part of a range of driver-selectable target values for engine power.
4. A method as claimed in claim 3, wherein the relationship is so modified as to provide a reduction in actual value in relation to driver- selected target value in said part of the range of selectable target values.
5. A method as claimed in claim 4, wherein the relationship is so modified that the actual value is unchanged by change in the driverselected target value within said part of the range.
6. A method as claimed in any one of the preceding claims, comprising 1 the preliminary step of driver selection of the target value for engine power by way of an accelerator pedal.

z
7. A method as claimed in claim 6, wherein the relationship is modified by causing travel of the accelerator pedal to be ineffective for variat5 ion of the driver selectable target value within a range of such travel.
8. A method as claimed in claim 7, wherein said range of travel is substantially 75 percent of the total effective pedal travel starting from rest.
9. A method as claimed in claim 4, wherein the reduction is by sub10 stantially 30 percent.
10. A method as claimed in any one of the preceding claims, comprising the step of providing a warning indication simultaneously with said step of modifying.
11. A method as claimed in claim 10, wherein the warning indication 15 is at least one of an optical signal and an acoustic signal.
12. A method as claimed in claim 1 and substantially as hereinbefore described with reference to the accompanying drawings.
13. Equipment for reporting a fault condition in a motor vehicle with an engine controllable in power by the driver of the vehicle, the equip20 ment comprising means to modify a given usual relationship between 9 actual value of generated or delivered engine power and driver-selected target value of engine power in response to recognition of a fault in a system of the vehicle, the relationship being modified in recognisable manner in at leas-'L-. one range above a target value for engine idling speed.
14. Equipment as claimed in claim 13, comprising a target value generator controllable by the driver to generate the target value of engine power, the means to modify being arranged to influence the effect of the generated target value.
15. Equipment as claimed in claim 13 and substantially as hereinbefore described with reference to the accompanying drawings.

Published 1988 at The Pater., Wice- Rate House. 6671 High Lonicn 117C1 F. 47P 'F-='her copies nay be ob:air.ed Salles Branch. St Ma7, CrayOrzir.g-,::,-.. Ken, ERS 3R1: Pr.r..e ',y M'j2-plex te--hriqi.:es M_ S Ma-n- Crky. Ken Con 1 87 fro.-. The Patent Office