CONTROL UNIT FOR THE PILOT LAMPS OF THE INSTRUMENT BOARD OF AN AUTOMOTIVE VEHICLE

Abstract: A control unit for verifying the functionality of the pilot lamps installed on the instrument board of an automotive vehicle is proposed, wherein a central control unit continuously monitors the functional condition of the devices monitored by the pilot lamps and wherein by means of hand-operated actuation means, the functionality of the pilot lamps can be verified also while the car is running.

Description: The present invention relates to a control unit for the pilot lamps installed on the dashboard of an automotive vehicle equipped with an internal combustion engine, in order to display the operating status and the critical conditions of determined devices concerning the drive of the vehicle, wherein said control unit comprises a central control unit operatively connected with the same pilot lamps, and with sensors suitable for detecting the operating status and the critical conditions of said devices. Generally, the instrument boards positioned on the dashboard of the automotive vehicles comprise the displays of several apparatuses, capable of measuring the value of physical quantities concerning the drive of the same vehicle, such as the tachometer, the odometer, and so forth, and a certain number of pilot lamps, which display the operating status of determined pieces of equipment, or critical conditions of physical quantities concerning the drive of the vehicle. When the instrument board of an automotive vehicle is designed, a thorough investigation into the layout, the dimensions, the types of displays to be adopted is required, in order to find out the best solution for realizing and correctly positioning the various displays within the visual field of the driver and enable this latter to find out the information with rapidity and precision, without distracting his attention from the road, and from the traffic conditions. This general criterion is particularly valid for the pilot lamps, because all the operating faults which occur during the vehicle running considerably worry the driver, whose attention, if he finds difficulties in correctly identifying the site of the fault, is distracted from the drive. Due to this reason, the present trend is to concentrate all of the optical pilot lamps in a particular area of the instrument board, in such a way that they are in front of the driver instead of being partly installed on the instrument board, and partly on a separate panel mounted on the dashboard. Furthermore, in several cases the solution is adopted of camouflaging the graphic symbols relevant to the optical pilot lamps, So that they are not normally visible, and become visible only when so needed: either when their efficiency is tested, or when they light up in order to display the operating status of a device, critical conditions, faults, so that the driver's attention is surely called to them exactly when the situation so requires. Usually, a group of optical pilot lamps are directly connected with the respective sensors, whilst a second group of pilot lamps are operatively connected with the respective sensors through a central control unit. The central control unit typically as shown in the publication "Journal de la Société des Ingénieurs de l'Automobile, no.8, Nov. 1984, Paris, pages 92-96 ; M.Claes : Les Centrales de Controle-Veglia-control-" verifies the functionality of the pilot lamps belonging to the second group, by turning them on, when the switchgear driven by the starting-up key is turned on, before the engine is started up; subsequently, during the running of the vehicle, only in case particular operating statuses, critical conditions, or faults, of the devices, occur, the pilot lamps belonging to the first group are directly turned on by the respective sensors, whilst those belonging to the second group are turned on by the central unit. From "Betriebsanleitung BMW 316-323i (pages 2-15)" is also known another unit which is capable of verifying at any time the functionality of control lamps, without any specific mention to the presence of control sensor means. The purpose of the present invention is to improve the systems known from the prior art, in particular as regards their efficiency and reliability. This result is achieved by means of a control unit for the pilot lamps which, as compared to the systems known from the prior art, is capable of verifying at any time the functionality of the same pilot lamps, and which is also capable of analysing the conditions of the sensors by means of a very quick and reliable procedure. According to the invention there is therefore proposed a control unit having the features of claim 1. Therefore, with this solution, the sensors, and hence the devices, relevant to the first group of pilot lamps, are continuously supervised, so that possible anomalies can be quickly signalled to the driver; moreover, the driver can verify that the absense of fault signalling is not due to faults in pilot lamps operation, because whenever he so regards as necessary, he can verify the functionality of the pilot lamps belonging to both pilot lamp groups, even while the vehicle is running. Characteristics and advantages of the present invention are illustrated now by referring to the hereto attached drawings, wherein a preferred form of practical embodiment of the invention is depicted for exemplifying, non-limitative purposes. In Figure 1 the pilot lamp control unit according to the present invention is shown by means of a block diagram; in Figure 2, the value is shown as a function of time, of some signals processed by the control unit of Figure 1; in Figure 3 an instrument board is depicted, the pilot lamps of which are managed by the control unit of Figure 1. In Figure 1, by the reference numeral 10 the block is generally indicated, which is formed by the central control unit, comprising a programmed microprocessor and the interfaces for connection with the external devices. By the reference numeral 11 the arrows are generally indicated, which represent the signals coming from the sensors, not shown in the figures, which are operatively connected with the vehicle devices whose operating status and critical conditions, or any faults, are to be detected by means of the central control unit 10. These are generally the devices which are most difficult to be checked by the driver, and the relevant sensors are, e.g.: the sensor of maximum temperature of engine coolant liquid, the sensor which monitors the level of the same coolant liquid, the sensor of minimum pressure of engine lubricant, the sensor which monitors the level of the same lubricant, the sensor which monitors the level of the liquid of such services as the rear window washer and the headlights washer, the sensor detecting the jamming on of the parking brake, the sensor of the level of the liquid inside the braking system, the sensor of the wear of the brake pads, the sensor of the turning on of the stop lights, the sensors detecting the conditions of opening of the doors and bonnets of the vehicle. The signals 11 are generally of low/high type, because they are generated by sensors formed by switchgears, e.g., of the normally closed type, so that the electrical continuity of the electrical circuit relevant to the same sensor can be verified too. To the central control unit 10 also the signal come, which are represented by the arrows 12, 13, 14, the first one of which comes from the switchgear (not shown) driven by the engine starting-up key in its position of running, or of starting up, and is hence of low/high type; the second one of which comes from an auxiliary switchgear (not shown), manually controlled by the driver, e.g., by means of a pushbutton, and is also of low/high type; and the third one of which is supplied by a device which detects the revolution speed of the engine. From the central control unit 10 the transmission line departs, which is generally indicated by the reference number 15 and is formed by the lines 16, 17, 18, the first of said lines being for the transmission of a clock, the second for the serial transmission of the data relevant to the signals 11, the third for the transmission of a load. The line 15 is connected with the driver represented by the block 19, which is preferably formed by an integrated circuit comprising a shift register 25, a latch 26, and a buffer 27. From the driver 19 the lines depart, which are generally indicated by the reference numeral 20, for the transmission of the signals to the optical pilot lamps installed on the instrument board 21, mounted on the dashboard of the automotive vehicle. Preferably, the graphic symbols of the pilot lamps are normally invisible, and become visible only when said pilot lamps turn on, whether for the check of functionality, and for signalling particular functional statuses or faults to the relevant devices. These pilot lamps, schematically represented by small squares, belong to a first pilot lamp group, generally indicated by the reference number 22, which comprises the pilot lamps corresponding to the sensors operatively connected with the central control unit 10, and to a second pilot lamp group, generally indicated by the reference numeral 23, comprising the pilot lamps directly connected with the respective sensors. These latter sensors, the signals of which are represented by the arrows generally indicated by the reference numeral 24, can be the same actuators of the devices directly controlled by the vehicle driver, and which can be hence directly and immediately checked, such as, e.g., the turning indicators, parking lights, low beams, high beams, fog lights, rear fog lights, emergency lights, rear window heater. These sensors can also be those provided in order to monitor particular functions, such as, e.g., the charging status of the generator of electrical power, the fuel reserve inside the fuel tank. Thus, the lines 20 departing from the driver 19 either transport the signals of actuation of the pilot lamps of both pilot lamp groups 22 and 23, or transport in parallel and simultaneously the drive signals, indicating either normal or abnormal statuses, of the pilot lamps of pilot lamp group 22. When the engine starting-up key is brought to its running position, and the relevant signal 12 comes to the central unit 10, this latter feeds the pilot lamps of both pilot lamp groups 22 and 23 with electrical current, temporarily and for a preestablished time, so that all pilot lamps light up and enable the driver to visually verify their efficiency. At the end of said pre-established time period all pilot lamps are turned off, except those relevant to any possibly turned-on devices, those relevant to all devices under abnormal conditions, and also that relevant to the electrical power generator, if the engine of the vehicle has not been started up yet. The central control unit 10 also turns off the pilot lamp signalling the minimum oil pressure, because it is so prearranged as to consider as normal the situation of pressure absence when engine is stationary. In fact, the central control unit 10 is capable of distinguishing the condition of stationary engine from the condition of running engine, by means of the signal of engine revolution speed 14; only if this signal exceeds a pre-established value of minimum threshold, for a time longer than a predetermined time period, the central control unit 10 assumes that the engine has been started up. After engine is started up, if the generator operates normally, the relevant pilot lamp turns off, and the central unit 10 carries out the verification of the minimum pressure of engine lubricating oil: if the minimum pressure is normal, the relevant pilot lamp remains turned off, whilst in case of an anomaly it is turned on, but only if the anomaly lasts more than a pre-established time period, in order to prevent wrong signallings due to transient changes in lubricant level. By means of the device proposed by the present invention, the functionality of the pilot lamps belonging to the pilot lamp groups 22 and 23 can be verified also while the automotive vehicle is running, by manually switching on the switchgear, the signal of which is represented by the arrow 13. In this case too, the central control unit 10 feeds all the pilot lamps with electical current, while this switchgear is kept closed, enabling the driver to rapidly and reliably check their functionality. The status of the signals 11 relevant to the pilot lamp group 22 is continuously monitored by the central control unit 10, and the data sent to the driver 19 are updated during successive cycles of detection and transmission, as shown in Figure 2. In correspondence of each clock 28 entering the driver 19, to the shift register 25 the data 29 are progressively loaded, which are serially transmitted through the data line 17; such data are either constituted by the signal of excitation of the pilot lamps of both pilot lamp groups 22 and 23 in order to verify their functionality, or by the signals indicative of the functional status of the devices controlled by the pilot lamps of the first pilot lamp group 22. The contents of the shift register 25 are transferred to output when the load 30 turns to high, and is thus stored in the buffer 27 until the following loading, ready to be sent to the pilot lamps belonging to pilot lamp group 22 in parallel, and, in the specific case, also simultaneously, through the lines 20. In Figure 2, shown are: the transmission beginning, at the top; and the transmission end, at the bottom. The period of each detection and transmission cycle can be of the order of hundreds of milliseconds, e.g., 250 milliseconds, and therefore any possible anomalies in the devices checked by the pilot lamps belonging to pilot lamp group 22 can be displayed extremely quickly on the instrument board 21. In the instrument board 21 shown in Figure 3, some instruments are shown, such as the tachometer 31, the revolution indicator 32, the voltmeter 33, the pressure gauge 34, the thermometer 35, the fuel level gauge 36. In the instrument board, also the pilot lamps 22a-22o of pilot lamp group 22, and the pilot lamps 23a-23m of pilot lamp group 23 are shown, as they appear when are turned on, because they are normally invisible.

Claims: Control unit for pilot lamps suitable for displaying the operative status and the critical conditions of determined devices of an automotive vehicle equipped with an internal combustion engine, wherein the above said control unit comprises a central control unit (10) operatively connected with a first group of pilot lamps (22) and with sensors suitable for detecting the operative status and the critical conditions of the devices monitored by the pilot lamps belonging to the above said first pilot lamp group (22), whilst a second group of pilot lamps (23) is directly connected with the relevant sensors, and wherein the central control unit (10) is furthermore operatively connected with first actuation means driven by the engine starting key, the central control unit (10) being also operatively connected with said second group of pilot lamps (23), and with second hand-controlled actuation means for turning on the pilot lamps belonging to both above said pilot lamp groups (22,23) in order to verify their functionality, and wherein the same central control unit (10) is operatively connected with the pilot lamps belonging to both above said pilot lamp groups (22,23) by means of a driver (19) capable of sending excitation signals to the pilot lamps belonging to both said pilot lamp groups (22,23) in the presence of actuation signals coming from said first actuation means, or by said second actuation means, characterised in that said central control unit (10) is capable of continuously detecting, during successive updating cycles having a predetermined period, the functional condition of the sensors, and therefore of the devices monitored by said first group of pilot lamps (22), and is capable of serially sending, during successive transmission cycles having the said predetermined period, the corresponding signals to said driver (19), which transmits them in parallel to the pilot lamps belonging to said first group of pilot lamps (22). Control unit according to claim 1, characterised in that one of the above said sensors is suitable for monitoring the pressure inside the lubricant system of the above said engine, and that the above said central control unit (10) is also operatively connected with detector means detecting the speed of revolution of said engine, in order to distinguish the condition of stationary engine from the condition of running engine, when the same revolution speed exceeds a certain threshold value for a time longer than a predetermined time period, wherein the above said central control unit (10) is so prearranged as to regard as normal the situation of absence of pressure when the engine is stationary. Control unit according to claim 1, characterised in that the above said driver (19) is formed by an integrated circuit comprising a shift register (25), a latch (26), a buffer (27), wherein the above said central control unit (10) is connected with the above said driver (19) by means of a transmission line formed by a line for the transmission of a clock (28), by a line for the serial transmission of the data (29) relevant to the signals coming from the above sensors, and by a line for the transmission of a load (30).

Inventors: GEROSA, ALLESSANDRO, ROGORA, EDOARDO, SUSA, ANDREA, VILLA, EZIO
Applicants: FIAT AUTO S.P.A.
Application year: 1988
Main classification: B60Q11
IPC codes: B60Q11