GB2259149A

GB2259149A - Making multiple use of a reference mark

Info

Publication number: GB2259149A
Application number: GB9217788A
Authority: GB
Inventors: Werner Jundt; Norbert Miller
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1991-08-24
Filing date: 1992-08-21
Publication date: 1993-03-03
Anticipated expiration: 2012-08-21
Also published as: DE4128158A1; JPH05196477A; GB9217788D0; GB2259149B

Abstract

Multiple use is made of a reference mark 12 or 12' on a disc 10 coupled to an i.c. engine shaft 17, e.g. to detect the type of transmission present in a vehicle fitted with the engine. The disc 10 of Fig. 1 may be used in the case of a motor vehicle having manual transmission, the resultant pulse train being minus one pulse, whereas a disc as in Fig. 2 or 2a and producing an extended pulse as the reference mark is used with a motor vehicle having an automatic transmission. The reference mark is detected in the control unit 15 by measurements and comparison of pulse time intervals, and it is simultaneously evaluated whether the corresponding signal is of a high or low level. Alternatively, the same engine disc may be used in all vehicles, and electric inversion incorporated in or omitted from the pulse waveform generating circuitry in accordance with the type of transmission present. With the device described, it is possible also to differentiate other conditions, for example use of mechanical/electrical throttle control, leaded/unleaded fuel etc. <IMAGE>

Description

2 2 5 914 s

-1DESCRIPTION

A DEVICE FOR THE MULTIPLE USE OF A REFERENCE MARK The invention relates to a device for the multiple use of a reference mark.

For the purpose of detecting the angular position of a rotating part, for example, of a crankshaft or cam shaft of a motor vehicle, a transmitting disc is normally disposed on the rotating shaft, the transmitting disc having angular marks distributed uniformly around its periphery, wherein at least one angular mark or an intermediate space between two angular marks are designed differently as a reference marker.

These angular marks are scanned by a stationary sensor, for example, an inductive sensor, and processed downstream in an evaluating unit into a pulse sequence. This pulse sequence is then evaluated in a control unit, wherein the intervals of time between similar edges of the pulse sequence are measured and are then recognised as a reference mark, when at least one interval of time differs characteristically from at least one of the preceding or subsequent intervals of time.

A device of this type is, for example, known from DE-OS 34 23 664 and after detecting the reference mark facilitates the exact control and regulation, for -2example, of ignition or fuel injection in an internal combustion engine.

As a plurality of information is required to control a modern internal combustion engine, it is necessaryf either to use a plurality of sensors or complicated signal evaluators to obtain additional information.

Information, which is essentially required by the control unit of a motor vehicle, is the information as to whether the vehicle has an automatic or a manual transmission. This information was previously obtained by evaluating the positions of the individual switches and feeding it to the control unit. Therefore, for example, a possibility is quoted in DEOS 37 44 222, with which it can be recognised automatically whether an automatic transmission is present or a manual gear change.

In so doing, the fact is evaluated that, with vehicles having a manual transmission there is a direct connection between the starter switch and the starter relay, whereas with vehicles having an automatic transmission. there is an additional switch between the starter switch and the starter relay, which is closed or opened depending on the position of the selector lever. This additional switch has the effect that with vehicles having an automatic 1 -3transmission, there is, on one edge of the starter switch, a positive potential, when the vehicle is running, whereas at the same point on vehicles having a manual transmission, there is an earth potential. This provides the possibility, by evaluating the level of voltage, to detect at this point whether the vehicle has a manual transmission or an automatic transmission.

Under certain circumstances, however, this evaluation of the value is extremely costly and gives rise to additional costs. Moreover, it is only possible to carry out the evaluation during the startup procedure, so that it is no longer possible to discriminate in the event of interference while the vehicle is travelling.

The object of the invention therefore is to further develop a device for detecting reference marks, which is in any case required in each vehicle, in such a way that it is not only detected when a reference mark appears, but the type of reference mark is also recognised, so that when recognising the type of reference mark, additional information with respect to the motor vehicle is thus supplied, if identical vehicle types are fitted with uniform reference marks.

In accordance with the present invention there is provided a device for the multiple use of a reference -4mark, comprising a transmitting disc having a plurality of similar marks and at least one reference mark, which differs from the remaining marks, connected to a rotating shaft, a sensor, which scans the transmitting disc and produces a pulse sequence, and a control unit evaluating the pulse sequence and detecting the at least one reference mark therefrom, if at least one space between similar pulse edges differs from the remaining spaces, wherein different reference marks are used for two conditions to be detected and the control unit checks which of the two reference marks is present.

This has the advantage that it is possible, almost without any additional costs, to detect a further condition of a motor vehicle.

It is particularly advantageous to use a device in accordance with the invention for detecting the type of transmission used. If, for motor vehicles having a manual change. a transmitting disc is used, for example having markers uniformally disposed about its periphery and whose reference marker is identified as one or two of the marks being omitted, moreover, for motor vehicles having automatic transmission, a transmitting disc is used whose reference mark is elongate in comparison to the other marks or as a disc with punched holes disposed uniformly therethrough, -5but with one hole missing, it is then possible to detect from the signal level detected by the sensor during rotation of the reference mark, which type of transmission is present.

Advantageously, the same transmitting disc can be used for both types of transmission, and for this purpose the normal output signal of the sensor is processed in the control unit for one type of transmission, and for the other type of transmission the inverted output signal of the sensor is processed.

It is particularly advantageous that it is detected as soon as the first reference mark appears, whether an automatic transmission or a manual transmission is present. It is then possible to repeat the detection process after each rotation of the crankshaft, in order to save computer capacity. It is, however, also possible to carry out the detection process only within a range of rotational speed which can be selected.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, in which:

Fig.1 is a highly schematic view of a device for detecting a reference mark of a transmitting disc used for vehicles having manual transmission, constructed in accordance with the present invention; Fig.2 illustrates schematically a further embodiment of the transmitting disc of Fig.1 used for automatic transmissions; Fig.2a illustrates schematically yet a further embodiment of the transmitting discs of Fig-1, used for automatic transmissions; Fig.3a illustrates a signal graph, which is obtained for the transmitting disc of Fig.l; and Fig.3b illustrates a signal graph which is obtained for the transmitting disc of Fig.2 or Figb.2a.

A transmitting disc 10 associated with the rotating shaft 17 of an internal combustion engine, for example a crankshaft or a cam shaft, has a plurality of similar marks 11 and a reference mark 12. The transmitting disc 10 is scanned by a sensor 13, which is connected to a processing unit 14, in which a square wave pulse U14 is produced from the pulses supplied by the sensor 13.

The square wave pulse sequence U14, (which is plotted in Fig. 3 over time T), is fed to a dataprocessing device, normally the control unit 15 having a volatile memory of an internal combustion engine, where it is evaluated.

In so doing, the intervals of time between the appearance of the edges of similar angular marks are -7determined. In Fig. 3, for example, three intervals of time TO, T1, T2 are plotted, wherein the voltage or pulse U14. which is plotted over the time T, is obtained for a transmitting disc, which has the surface form of the transmitting disc 10 which is illustrated in Fig. 1 and which has the markings 11 and a reference mark 12 formed by an elongated gap.

Fig. 3b illustrates the same state of affairs for a transmitting disc as shown in Fig. 2, having a reference mark, which is formed by an extended marking and the same voltage distribution occurs for a punched disc as shown in Fig. 2a, having a hole missing.

The measurements of time for determining the times TO, Tlf T2 etc., which expire in the control unit 15, can be carried out as pure measurements of time. It is equally possible to obtain these intervals of time by counting out a cyclic frequency by means of one or more counters.

The reference marks are always detected if the individual times differ from each other in a way which can be specified. One extremely reliable possibility for detecting reference marks has proven itself in the method known from DE-OS 34 23 664, i.e. to recognise a reference mark. if the condition T2 < Tl>TO is complied with. It is, however, also sufficient to determine the reference mark after the completion of -8Tl> N TO, wherein N is a factor which amounts to approximately 1.2 to 1. 7 and prevents any increases in time as a result of reducing the rotational speed. from leading to reference marks being detected erroneously.

In accordance with the invention. a transmitting disc, as illustrated in Fig. 1, is used in motor vehicles having manual transmission, whereas, with vehicles having an automatic transmission, a transmitting disc as shown in Fig. 2 or 2a is installed. The pulse sequences which are obtained in each case (as plotted in Fig. 3), show that, in the first case (Fig.3a), the pulse sequence U14 has its low value (low-level) when the reference mark appears. whereas in the other case, pulse sequence U14 adopts the high-condition (high-level) when the reference mark appears. The signal level is therefore characteristic for the type of transmission.

This is detected in the control unit 15, in which the gap in the level of the input-port is scanned for the purpose of collecting the pulse sequence of the transmitter. The inquiry can, for example, be made as far as the software is concerned, after the time Tl>N TO.

As an alternative to the above described possible solution, it is possible to manage with one transmitting disc for both types of transmissions, if with the manual transmission, the normal output signal of the sensor is evaluated, whereas if there is an automatic transmission, the inverted signal of the sensor is evaluated. This inverted signal can be obtained at the same time by reversing the poles of the transmitter. Furthermore, it is possible to provide an inverter 16 between the sensor 13 and the data-processing device, or rather control unit 15. The signals are evaluated in the control unit again the same way as when using different transmitting discs.

The first detection, as to which type of transmission is present, occurs when the reference mark first appears. The possibility can be made available to repeat this detection process with each detected reference mark. It is also possible to carry out the process of detecting the transmission only when there is a preset specifiable rotational speed. It is furthermore possible to carry out the process of detecting the transmission during a preset time window.

With the present invention, it is, however, not only possible to detect the type of transmission once, -10but also to detect any variants, wherein in each case it is possible with one reference mark to detect two variants. Examples of such variants are: whether present mechanical throttle control or electrical throttle control (E-Gas) is present; whether it is necessary to have leaded or unleaded fuel; vehicles with or without air conditioning etc. Fundamentally, any binary variants can be detected.

---------------------------------------------------------

Claims

1. A device for the multiple use of a reference mark, comprising a transmitting disc having a plurality of similar marks and at least one reference mark, which differs from the remaining marks, connected to a rotating shaft, a sensor, which scans the transmitting disc and produces a pulse sequence, and a control unit evaluating the pulse sequence and detecting the at least one reference mark therefrom, if at least one space between similar pulse edges differs from the remaining spaces, wherein different reference marks are used for two conditions to be detected and the control unit checks which of the two reference marks is present.

2. A device for the multiple use of a reference mark, comprising a transmitting disc having a plurality of similar marks and at least one reference mark, which differs from the remaining marks, connected to a rotating shaft, a sensor, which scans the transmitting disc and produces a pulse sequence, and a control unit evaluating the pulse sequence and detecting the at least one reference mark therefrom, if at least one space between similar pulse edges differs from the remaining spaces, wherein the same reference mark is provided for the two spaces which are to be differentiated between and for the first -12space to be differentiated. the pulse sequence is evaluated and for the second space to be differentiated, the inverted sensor signal is evaluated and the control unit checks which signal is supplied.

3. A device as claimed in one of the aforementioned claims, in which the input port is additionally scanned for its level for the purpose of acquiring the pulse sequence of a transmitting disc, during the presence of the reference mark.

4. A device as claimed in claim 1, 2 or 3. in which the conditions to be differentiated are a manual transmission or an automatic transmission and that, for a vehicle having manual transmission a reference mark is provided which is formed by at least one missing mark and that for a vehicle having automatic transmission, an extended mark is provided as a reference mark.

5. A device as claimed in claim 4, in which the type of transmission fitted is detected each time the reference marks appears.

6. A device as claimed in claim 4, in which the type of transmission fitted is detected when the reference mark appears for the first time and the type detected is stored in the non-volatile memory of the control unit.

W c

6. A device as claimed in claim 4, in which the type of transmission fitted is detected when the reference mark appears for the first time and the type detected is stored in the volatile memory of the control unit.

13-

7. A device as claimed in claim 1, 2 or 3, in which the conditions to be differentiated are a mechanical throttle control and an electrical throttle control, leaded or unleaded fuel, vehicle with or without air conditioning.

8. A device for the multiple use of a reference mark, constructed substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

1-11-1 Amendments to the claims have been filed as follows space to be differentiated, the pulse sequence is evaluated and for the second space to be differentiated, the inverted sensor signal is evaluated and the control unit cheeks which signal is suD.Plied.

4. A device as claimed in claim 1, 2 or 3, in which the conditions to be differentiated are a manual transmission or an automatic transmission and that, for a vehicle having manual transmission a reference mark is provided which is formed by at least one missing mark and that for a vehicle having automatic transmission, an extended mark is provided as a reference mark.