GB2203264A

GB2203264A - Electronic control system for a vehicle propulsion system

Info

Publication number: GB2203264A
Application number: GB08807196A
Authority: GB
Inventors: Gerhard Kirstein
Original assignee: Renk GmbH
Current assignee: Renk GmbH
Priority date: 1987-04-04
Filing date: 1988-03-25
Publication date: 1988-10-12
Anticipated expiration: 2008-03-25
Also published as: DE3711467C2; DE3711467A1; GB8807196D0; GB2203264B; IT8820000A0; IT1217381B

Description

1 1 1 ELECTRONIC CONTROL SYSTEM

SPECIFICATION

0, 3 This invention relates to an electronic control system for a propulsion system, particularly for vehicles, which interacts with pulse-width-modulated components of the propulsion system.

Known systems use only a single microcomputer.

This controls non-pulse-width-modulated components.

In spite of high operational speeds of the known control devices and microcomputer. material time differences arise between the occurrence of a particular operational situation and the point in time at which specific control measures or regulating measures are taken in dependence upon the operational situation.

It is an object of the present invention substantially to reduce the time. delay which occurs between the occurrence of a specific new operational condition and the beginning of a reaction process to be carried out in dependence on that new condition. BY means of the present invention one can thus create to a substantial extent a "real time control". Also, more complex regulation curves can now be realised in acceptable times. Moreover. a certain redundancy is created which permits -the effective use of an integrated diagnostic programme.

In accordance with the present invention there is 30 provided an electronic control system for a propulsion system, particularly for vehicles, which interacts with pulse-width-modulated components of the propulsion system. wherein at least two microcomputers are connected together by data links, wherein one of said microcomputers receives desired valuii inputs providing 2 data for the desired operation of the propulsion system and controls or regulates non-pul se -width- control led components of the propulsion system in dependence thereon, and in which the other or another microcomputer controls or regulates pglse-widthcontrolled components of the propulsion system according to a control code through said one microcomputer.

By this means the other or said another microcomputer is not delayed in its reaction time by the command performance times which are necessary to create the modulation frequency and the pulse width associated therewith.

By this means one achieves a system in which upon the occurrence of a change in the operational conditions, a reaction process is initiated substantially without delay, particularly upon the need for corrective measures as a result of deviations from a desired value.

According to one preferred embodiment of the invention the control of the pulse-width-controlled components takes place in dependence upon changes in rotation per unit. time of a part or parts of the propulsion system after the transfer of the control code.

According to a further preferred feature of the invention one can provide that the pulse-width controlled components are actuated according to a pre programmed temporal control process.

According to another preferred feature of the invention it is provided that the speed of rotation of a part or parts of the propulsion system is measured both by said one microcomputer and also by the other or another microcomputer.

It may be preferable to arrange that the speed of 1 1 1 5.

3 rotation measurement is fed according to different dividing ratios to said one microcomputer and to the other or said another microcomputer. Thereby, the measured frequency which is dependent upon the speed of rotation is transformed according to the dividing ratio to a lower frequencyy which substantially eliminates geometrical deviations, for example with gear wheels, during the period of a measuring process.

Preferably, each microcomputer of the control system of the present invention includes its own error diagnostic circuit for determining faults in the control system itself and in peripheral devices, and status-function codes and error codes are continuously exchanged between the microcomputers by way of the data links.

It is desirable that each microcomputer should include an emergency programme which is effective if faults occur. Such emergency programmes can be arranged so that the propulsion system can run only up to a maximum speed of rotation or only while remaining below a specific operating temperature or the like.

The present invention results in a real reduction in the reaction time of the control device. The solution of this time problem is achieved according to the invention essentially by virtue of the fact that a number of microcomputers are provided which all work contemporaneously but according to different programmes.

Within the framework of the present invention the following terms used herein have the following definitions:

"Propulsion system": Gears; engines and motors, especially internal combustion engines, electric motors, oil engines; turbines.

"Non-pulse-width-control led components": So-called 4 black/white components which each can take up only one or other of two different switched states according to control signals. We are talking &here particularly about proportional valves, stepping motors, servo motors and similar setting components which, under the control of a signal, take up one of several possible fixed operational states.

"Pulse-width-controlled components": Components whose signals controlling them have the form of pulses, the pulse width of which varies according to the signal value. The components take up a particular operational state depending upon the width of the pulse. Such pulse-width-controlled components include for example valves and setting members whose setting value is dependent on the pulse width of the signal controlling it.

The preferred field of utilisation of the electronic control device of the present invention is for propulsion systems of road vehicles. However, such control devices can also be used for the propulsion systems of ships, aircraft and stationary apparatus.

The "desired value inputs" of said one microcomputer include signals from devices with which the propulsion system is used, particularly signals for example from the accelerator pedal, the brake pedal, from gears which are controlled manually, from a pre programmed automatically switchable transmission gear system, and from other like elements which determine the operation of the sy stem.

In order that the invention may be fully understood, one presently preferred embodiment of control system in accordance with the invention will now be described by way of example and with reference to the accompanying drawing which Is a block schematic diagram of the control system.

1 S 1 i The electronic control device shown in the drawing comprises a first microcomputer 2 and a second microcomputer 4 which are connected to each other by data links 6, which form a bi-directional data bus by means of which the two microcomputers can exchange data reciprocally. The first microcomputer 2 is connected to a device, which in the present case is a road vehicle 8, which incorporates a propulsion system 10. From the vehicle 8 there are connections to the first microcomputer 2, namely a connection from a gearchange selector 12 for the pre-programmed switching of the propulsion system 10 by way of a desired value input 14, a connection from an accelerator pedal 16 by way of a desired value input 18. and a connection from a brake pedal 20 by way of a desired value input 22.

Additionally, the microcomputer 2 is connected by means of a signal output 24 to a warning light 26 and by means of a signal output 28 to an indicating instrument on the vehicle 8.

The propulsion system 10 in this embodiment comprises a gear system which is switchable automatically under load and which is designed for an internal combustion engine, electric motor or a turbine. The propulsion system includes at least one non-pulse-width-modulated component 32 controlled by the first microcomputer 2. This can be a magnetic valve. a servo motor or a similar setting element. Preferably, at least one such component 32 is provided for each switchable gear of the propulsion system 10.

Furthermore, the propulsion system 10 includes at least one tachometer 34 which produces a frequency signal dependent upon the measured speed of rotation, with this frequency signal being fed by way of a frequency divider 36 to the first microcomputer 2 and by way of a second frequency divider 38 to the second microcomputer r k 6 4. The first frequency divider 36 divides the frequency by the factor "x" to a first lower frequency, and the second frequency divider 38 divides the frequency by a factor "y" to another lower frequency.

The frequency dependent upon the speed of rotation is consequently fed directly to both microcomputers 2 and 4, and consequently the smallest possible amount of time is lost in the frequency transmission. The two, or more than two, independent frequency inputs can also be used for diagnostic purposes. A temperature sensor 40 and a pressure switch 42 are likewise connected to the first microcomputer 2 and give their operational values of the propulsion system 10. obviously. a plurality of temperature sensors 40 and pressure switches 42 could alternatively be provided. The temperature sensor could be used for the measurement of the temperature of oil which serves for lubrication and cooling in the propulsion system. Furthermore. it could serve for the temperature measurement of other cooling liquids. The pressure switch or switches 42 could serve for the measurement of the oil pressure or for the measurement of cooling liquids and other-pressures.

The tachometer 34, temperature sensor 40 and 25 pressure switch 42 provide real value outputs from the propulsion system. In dependence upon these real values, and In dependence upon the desired values on the desired value inputs 14, 18, 22, the microcomputer 2 controls or regulates the non-pulse-width-modulated components 32 and the second microcomputer 34 controls pulse-width- modulated components 46 of the propulsion system 10. Such pulse-width- modulated components 46 of the propulsion system 10 could be flow valves which open and close to a greater or lesser extent depending upon the width of the pulses.

-1 If 7 The two microcomputers 2 and 4 contain programmes for the mutual transfer of information as to function status, for determining and transmitting information concerning errors or defects, and for operating the whole system in accordance with emergency programmes when faults occur. For this purpose. at least one emergency programme is contained in each microcomputer 2 and 4.

8

Claims

CLAIMS:

1. An electronic control system f or a propulsion system, particularly for vehicles, which interacts with pulse-width-modulated components of the propulsion system, in which at least two microcomputers are connected together by data links, in which one of said microcomputers receives desired value inputs providing data for the desired operation of the propulsion system and controls or regulates non-pulse-width-control led components of the propulsion system in dependence thereon, and in which the other or another microcomputer controls or regulates pulse-widthcontrolled components of the propulsion system according to a control code through said one microcomputer.

2. A control system according to claim 1, in which the control of the pulse-width-controlled components is effected in dependence upon changes in rotation per unit time of a part or parts of the propulsion system after the transfer of the control code.

3. A control system according to claim 1, in which the pulse-widthcontrolled components are actuated according to a pre-programmed temporal control process.

4. A control system according to any preceding claim, in which the speed of rotation of a part or parts of the propulsion system is measured both by said one microcomputer and also by the other or another microcomputer.

5. A control system according to claim 4, in which the measured speeds of rotation are fed to said one microcomputer and to the other or another microcomputer according to different dividing ratios.

1 1 9

6. A control system according to any preceding claim, in which each microcomputer includes its own fault diagnosis circuit for the determination of faults in itself and in peripheral apparatus, and in which status function codes and error codes are exchanged continuously between the microcomputers by way of the data links.

7. A control system according to any preceding claim, in which each microcomputer includes an emergency programme which is effective when faults occur.

8. An electronic control system substantially as hereinbefore described with reference to the accompanying drawing.

PubUBhed 1988 at The Patent Office, State Home, CW 1 Holborn, London WC 1R 4Tp. Further copies may be obtained from The Patent Office. Sales Branch St Mary Cray, orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary, Kent. CO- 1187.