GB2256505A

GB2256505A - Device for fault storage in vehicle control equipment

Info

Publication number: GB2256505A
Application number: GB9212001A
Authority: GB
Inventors: Ruediger Jautelat; Alwin Lutz; Walter Scharfe; Rainer Sommer
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1991-06-07
Filing date: 1992-06-05
Publication date: 1992-12-09
Anticipated expiration: 2012-06-05
Also published as: DE4118692C2; DE4118692A1; GB9212001D0; JP3107454B2; GB2256505B; JPH05157667A

Description

1 2 2 -165 'I, DEVICE FOR FAULT STORAGE IN VEHICLE CONTROL EQUIPMENT The

present invention relates to a device for fault storage in vehicle control equipment. Such control equipment can be, for example, a single control device, which is the only one in the motor vehicle or which operates independently of other control devices in respect of fault storage, or it can be a combination of several control devices with common fault storage. In the following, for the sake of simplicity only a single control device is discussed and it is assumed that it serves for control of the operating sequences of an internal combustion engine. However, it will be evident from the

description that the content of stored fault information is of no consequence, so that the control device can be that used for control of other functional elements in a vehicle, for example brakes, adjustable suspension, transmission and safety equipment.

Conventionally, a fault is entered into a fault storage device 15 when the fault has lasted for more than a preset time span. This time span typically amounts to a few seconds and its actual duration is dependent on the respective fault. Test sequences can be performed for significantly more than 100 different faults in present-day vehicle electronic systems. The fault storage device, however, does not contain storage space for all theoretically possible faults, since it is improbable that all these faults occur before the vehicle is taken to a service centre. Storage space is present, for example, for 20 to 30 faults. A single time counter serves for the measurement of the time span within which a fault is present. Typically, a second fault occurring during the presence of a first fault can be attended to only when the time span for the first fault is no longer being measured by the time counter, wither because the fault has disappeared or because the preset time span for this fault has been exceeded. Another variant consists in restarting the counter on the occurrence of each fault and, on elapsing of the last set time span, entering into the fault storage device all faults still present at this instant.

It has been proposed in a prior patent application (DE-A-40 40 927) to provide a time counter storage space for each fault in the fault storage device and to register whether or not the counter has run down. Fault information is entered into the fault storage device on the occurrence of a fault and a time span predetermined for this fault is set in the time counter storage space. At the same time, it is registered in the fault storage device that the time counter has not yet run down. This information is used for blocking the access to this fault storage space in such a manner that the fault is evaluated as such. Subsequently, the time counter is decremented. As soon as it has run down, the respective information is changed appropriately so that the fault is now permanently recorded as capable of being called up. There remains a need for a fault storage device in vehicle control equipment which needs little storage space, but permits individual treatment of faults occurring at the same time. 25' According to the present invention there is provided a device for fault storage in vehicle control equipment, comprising fault time counting means for detecting the time span for which a fault lasts, the counting means comprising m time counters, and fault storage means for storage of information relating to n faults, the storage means being arranged to record a fault as permanently capable of being called up when it has lasted for longer than a predetermined test time span respective to the fault, wherein m is greater than 1 and less than n.

The number m of the time counters is preferably selected so that it corresponds to the greatest number of faults which could typically occur at the same time in operation of a vehicle. It is to be noted in this case that states similar to faults briefly occur in transient operation states of vehicle equipment. The time spans associated with the individual faults are chosen so that an entry into the fault storage device takes place for only such faults which, because the respective time span is exceeded, can be actually classified as permanent faults and not as temporary faults during short, transient time spans.

In a practical application, 120 faults could, for example, be monitored; space is present in the fault storage device for 30 faults and the fault time span in the fault time counting means can at any time be monitored simultaneously for four faults. Thus, all faults which realistically may simultaneously occur can betreated individually without a time counter space for an individual fault having to be present for each region in the fault storage device.

An association should preferably be created between a time counter and the fault which the counter counts the time. One possibility for such association consists in that each time counter comprises a time storage space and a fault recognition storage space. The fault recognition is typically a fault number. Seven bits are needed for the distinction of 120 faults, eight bits already above 127 faults and also one byte in each case in view of the byte addressability of typical storage devices. In the case of four time counters, the fault recognition storage device thus needs four bytes or 32 bits.

Another possibility for the storage of the association consists in that each time counter comprises a time span storage and the fault storage device for each fault comprises a storage space for a time counter number. When four time counters are present, two bits are sufficient for the distinction of these four time counters. Sixty bits must then be held ready for a total of 30 storable faults. In spite of the bit number being increased, this arrangement may be more advantageous, since different bitoriented evaluated bytes, which are not yet fully utilised, can be present in the fault storage device, so that the two bits for the time counter number can be accommodated without requiring additional storage space.

Embodiments of the present invention will now be more particularly described with reference to the accompanying drawings, in which:

Fig. 1 is a block diagram of a fault storage device in control equipment of a motor vehicle; Fig. 2 is a block diagram of a first form of fault time counting means in the device; Fig. 3 is a block diagram of a second form of fault time counting means in the device; and Fig. 4 is a block diagram of a third form of fault time counting means and fault storage means in the device.

Referring now to the drawings there is shown in Fig. 1 a fault storage device, in the form of a randomly accessibly memory unit 10, in control equipment (not illustrated) of a motor vehicle. The RAM unit 10 comprises inter alia a region which serves as fault storage 5 device 11 and a region which acts as fault time counting equipment 12. A first variant 12. 1 of a fault time counting equipment is illustrated in more detail in Fig. 2. The equipment comprises four time counters Z1 to Z4, each with a respective time storage space and fault recognition storage space. Time spans T1, T2 and T4 are stored 10 in the time storage spaces and associated fault numbers, denoted by FN1, FN2 and FN4, in the recognition storage spaces. The numbering of the time spans and fault numbers indicates the sequence in which such data entered the counting equipment 12.1. This is also recognisable from the time spans shown in Fig. 2. The time span T1 amounts to only one second, thus has nearly run down from an initially set value of, for example, five seconds, whilst the time span T4 amounting to four seconds is still relatively long, thus has either just been set or has already run down somewhat starting from a time span of, for example, a six seconds. The third data item in the sequence of entry, thus time span T3 and a fault number FN3, have already been erased, for example because the associated fault disappeared again shortly after its occurrence.

If, starting from the storage state of the counting equipment 12.1 as shown in Fig. 2, a new fault appears, an initialised time counter is looked for. In the case of Fig. 2, this is the time counter Z3. Values T5 and FN5 are then entered in the counter Z3.

Which counter becomes free next, depends on which faults last or which of them disappears again before the time span set on its occurrence has elapsed. If all faults endure, starting out from the state according to Fig. 2, the time span in the time counter Z1 runs down first, which is thereupon initialised and accordingly is available for reception of new data.

It is disadvantageous in the storage organisation shown in Fig. 2 that the fault time counting equipment 12.1 must be examined in order to identify a free time counter on the occurrence of each fault. If all counters are running and none is free, all of the counters must be interrogated before this state is recognised.

This disadvantage does not exist in the counter organisation shown in Fig. 3. The fault time counting equipment 12.2, which is illustrated in Fig. 3, comprises a counter indicator storage region P as well as four time counters Z1 to Z4, which operate in corresponding manner to those described with reference to Fig. 2. The address of the first free time counter i filed in the storage region P; in the case of the illustrated example, the filed address is that of the counter Z4. The address is assumed with a width of 2 bytes. the time storage space and the fault recognition storage space in each time counter respectively comprise 1 byte.

With this storage organisation, it is necessary that whenever one of the time counters has run down, the contents of the time counters of higher number are transferred on each occasion into the next lower time counter. The address stored in the storage region P is then decremented by one address value, here 2 bytes. Because of this organisation, the time spans T1, T2 and T4 follow one after the other in successive counters in the counting equipment 12.2, whereas the sequence was T1, T4 and T2 in the equipment 12.1 according to the sequence in which a free counter was found during the respective 5 occurrence of a fault.

As long as a fault is present, the time span in the associated time span storage space must be decremented. The association between a respective fault and the associated time span is given in the fault time counting equipment 12.1 and 12.2 in that each time counter comprises both a time span storage space and a fault recognition storage space.

Another form of association between faults and time described by reference to Fig. 4. In this embodiment, counting equipment 12.3 comprises time counters each respective time span storage space. Four time counters again present; the occupation of the counters with time same as for the counting equipment 12.1 shown in Fig. 2.

The fault storage device 11, also illustrated in Fig. 4, comprises n storage regions F1 to Fn for n faults (n = 30). Each fault storage region is four bytes wide, wherein a fault number is stored in the first byte, fault type data are stored in the second byte and data concerning first and second operating magnitudes, for example rotational speed and load on the occurrence of a fault, for example a short-circuit in the connections of an air mass meter, are stored in the two further bytes. The fault type byte is bit-oriented, i.e. individual bits each communicate respective information data. In spans is now a fault time with only a Z1 to Z4 are spans is the the illustrated example, the state of the first bit indicates whether the test time has run down or not. The second and third bits indicate the counter number in the fault time counting equipment 12.3. The fourth bit indicates whether the fault is present in the actual operating cycle or not, the fifth bit indicates whether a warning lamp must light up or not for this fault, and the sixth, seventh and eighth bits each give respective further items of data.

As soon as a fault occurs in the case of the fault organisation according to Fig. 4, it is entered, in the fault storage device 11, in the next region following the already occupied regions and it is checked whether a time counter is free in the fault time counting equipment 12.3. In the illustrated example, this condition is fulfilled for the counter Z3. The test time span, which is respective to the type of fault that has just arisen and which is read out from a table, is then entered into this counter, the counter number is registered in the bits 2 and 3 in the fault type byte and the first bit is reset, whereby it is indicated that the test time is still running. As long as it is reset, the entered fault cannot yet be called up as such by fault routines. If the fault disappears before the set time span has elapsed, the fault entry is erased and the fault counter Z3 initialised, i.e. set to the value zero. If the test span thereagainst elapses, the first fault type bit is set, whereby the entered fault is able to be called up by all routines. The associated counter, here the counter Z3, is initialised at the same time by this elapsing, i.e. it stands at the value zero.

If the embodiment of Fig. 4 is modified according to that of Fig. 3, i e. an address indicator is added to the fault time counting equipment 12.3, then, whenever a counter becomes free and values must be transferred out of counters of higher number into the respective next lower time counter, the counter number recorded in the fault type byte must also be corrected correspondingly.

In the described embodiments, it has been presumed that the fault time counting equipment is provided in the RAM of a control equipment. A register arrangement, which is provided especially, can also be used, for example.

The fault time counting equipment need not necessarily comprise four time counters, but the number of the time counters must be so chosen that the test time spans for the typical total number of simultaneously occurring faults can be monitored individually. The typical total number of simultaneously arising faults depends parti-cularly on the number of faults monitored altogether and the sensitivity during monitoring. It will always be significantly smaller than the number of faults for which storage spaces are provided in the fault storage device.

It is assumed in the embodiment of Fig. 4 that information is stored in four bytes for each fault. However, a greater orlesser number of items of information can be stored for each fault. The content and the quantity of information data do not matter in the present case, only that a smaller number m of fault time counters is present for a larger number of n of storable faults. This device has the advantage that the respectively associated test time spans can be monitored separately for all simultaneously occurring faults without requiring as many time counters to be present as faults to be stored.

Claims

1. A device for fault storage in vehicle control equipment, comprising fault time counting means for detecting the time span for which a fault lasts, the counting means comprising m time counters, and fault storage means for storage of information relating to n faults, the storage means being arranged to record a fault as permanently capable of being called up when it has lasted for longer than a predetermined test time span respective to the fault, wherein m is greater than 1 and less than n.

2. A device as claimed in claim 1, wherein each time counter comprises a time span store and a fault recognition store.

3. A device as claimed in claim 1, wherein each time counter comprises a time span store andthe fault storage means comprises a store for a time counter number for each fault.

4. A device as claimed in any one of the preceding claims, wherein the counting means comprises a store for storage of the address of the first free one of the counters.

5. A device substantially as hereinbefore described with reierence to Figs. 1 and 2 of the accompanying drawings.

6. A device substantially as hereinbefore described with reference to Figs. 1 and 3 of the accompanying drawings.

7. A device substantially as hereinbefore described with reference to Figs. 1 and 4 of the accompanying drawings.