Arrangement and method for protection against abnormal currents in a starter motor circuit

Abstract

Arrangement for protection against abnormal currents in a starter motor circuit of a starter motor (1) connected to an internal combustion engine (2) of a motor vehicle (3), the arrangement comprising a device (24) configured to interrupt an abnormal current supplied to the starter motor, the arrangement further comprising - a sensor (13) configured to detect the presence of a starter control signal sent to the starter motor, - an element (17, 35) configured to measure a quantity indicative of the current supplied to the starter motor, and - a control unit configured to determine, on the basis of information from the sensor and the element, that an abnormal current is being supplied to the starter motor (1) under the condition that a current above a minimum level has been detected by measurement by the element (17, 35) and, at the same time, the sensor (13) has detected an absence of the starting control signal, and, if this condition is met, to control the device (24) such that it interrupts the current supplied to the starter motor, the arrangement being configured to be arranged in a motor vehicle (3) having a generator (7) connected in parallel with the starter motor (1), characterized in that the device (24) is configured to interrupt such an abnormal current at a point within a line (18) connecting the starter motor (1) in parallel with the generator (7).

Description

Technical field of the invention

[0001] The present invention relates to an arrangement for protection against abnormal currents in a starter motor circuit of a starter motor connected to an internal combustion engine of a motor vehicle, the arrangement comprising a device configured to interrupt an abnormal current supplied to the starter motor, and to a method for such protection according to the preamble of the appended independent method claim.

[0002] The service life of a starter motor is generally shorter than that of a motor vehicle. This means there is a significant risk of starter motor problems. Common failure modes can result in abnormal currents in the starter motor circuit, any of which can lead to thermal incidents and VOR (Vehicle Off-Road). Therefore, it is desirable to protect the starter motor circuit against such abnormal currents to avoid the potentially serious consequences of such currents. Such failure modes can arise, for example, from welding of the contacts of a connector or short circuits due to overheating or other insulation problems. State of the art

[0003] US 2008 315 683 A1 and US 2005 099 009 A1 disclose arrangements that measure the current flowing to a starter motor in a motor vehicle and interrupt the electrical power supply to the starter motor when a current above a predetermined value is measured.

[0004] DE 10 2013 016 093 B4 discloses a method for controlling a pyro-fuse provided in an electrical line connecting the generator and the starter of a motor vehicle to a battery of the motor vehicle, which pyro-fuse is controlled to disconnect the line when an accident signal indicating an accident in the motor vehicle is present, wherein the pyro-fuse is also controlled to disconnect the line when an overvoltage signal indicating an overvoltage at the generator and / or a switch signal indicating a faulty, permanently closed switching device for supplying current to the starter is present.

[0005] Further prior art related to the present disclosure is provided by document DE 10 2011 081 093 A1. Summary of the invention

[0006] The object of the present invention is to provide an arrangement and a method which, according to the introduction, are improved at least in some embodiments compared to such already known arrangements and methods.

[0007] This object relates to the arrangement which is achieved by providing such an arrangement with the features set out in the characterising part of the appended claim 1.

[0008] Thus, the arrangement is provided with a sensor configured to detect the presence of a starting control signal sent to the starter motor, an element configured to measure a quantity indicative of the current supplied to the starter motor, and a control unit configured to determine, on the basis of information from the sensor and the element, that an abnormal current is being supplied to the starter motor, under the condition that a current above a minimum level has been detected by measurement by the element and the sensor has simultaneously detected the absence of the starting control signal, and if this condition is met, to control the device so as to interrupt the current supplied to the starter motor.

[0009] Accordingly, the arrangement according to the invention interrupts a current supplied to the starter motor when no current is to be supplied to the starter motor because no starter control signal is present. This means that the current is an anomalous current that must be due to some type of fault in the starter motor circuit. This differs from known arrangements of this type, which do not take into account whether a starter control signal is present or not, but only interrupt currents that are above a high level.

[0010] According to the invention, the interruption of the current supplied to the starter motor must occur when current flows to the starter motor despite the absence of such a starting control signal. This must be taken into account when interpreting the definition of the term "current above a minimum level," with the level accordingly set low compared to currents flowing during a failure, but still not zero, to avoid interruption when no failure occurs, but only some type of noise.

[0011] According to one embodiment of the invention, the control unit is configured to consider a current above a minimum level as being measured by the element only if such a current is continuously measured for a predetermined period of time, such as at least 0.1 s. This prevents the device from interrupting the current supplied to the starter motor when a sudden peak current occurs due to noise but without any fault in the starter motor circuit.

[0012] According to the invention, the arrangement is configured to be arranged in a motor vehicle having a generator connected in parallel with the starter motor. Furthermore, the device is configured to interrupt such an abnormal current at a location within a line connecting the starter motor in parallel with the generator. By interrupting an abnormal current supplied to the starter motor circuit in such a position, proper function of the generator can still be maintained.

[0013] According to a further embodiment of the invention, the control unit comprises a first logic element connected to the sensor and configured to send a logic 1 to a logic AND gate as long as the absence of the starter control signal is detected. It comprises a second logic element connected to the magnitude measuring element and configured to send a logic 1 to the AND gate when, as measured by the element, a current supplied to the starter motor is above the minimum level. Furthermore, the device is configured to be triggered by the logic 1 at the output of the AND gate to interrupt an abnormal current supplied to the starter motor. In this way, the control unit ensures that the interruption is only performed when this condition is met and no current is to be supplied to the starter motor.

[0014] According to a further embodiment of the invention, the device comprises a current interruption device arranged in a line connecting the starter motor to an electrical energy source, such as electric batteries, of the motor vehicle and configured to be triggered to interrupt an abnormal current supplied to the starter motor in the line, such as a pyrotechnic interrupter, a circuit breaker or a semiconductor switch, such as a transistor.

[0015] According to a further embodiment of the invention, the arrangement comprises an electrical energy source configured to supply electrical energy to the device to ensure the interruption of such anomalous current in the event of a failure of a connection between the electrical batteries of the motor vehicle and the device. The interruption of such anomalous current supplied to the starter motor can thus be performed without the need for electrical energy provided by the electrical batteries of a motor vehicle.

[0016] According to a further embodiment of the invention, the magnitude measuring element is configured to measure the current in a line for supplying electrical energy to the starter motor, e.g., by shunt measuring a voltage in the line or by a Hall element arranged in the line. This provides a reliable method for determining that an abnormal current is being supplied to the starter motor.

[0017] According to a further embodiment of the invention, the magnitude measuring element is configured to measure the voltage at a location in the starter motor circuit on the supply side of the starter motor with respect to ground as a quantity indicative of the current supplied to the starter motor. This provides another reliable method for determining that an abnormal current is being supplied to the starter motor. Such a supply would then be detected by a voltage at that location that differs from the voltage at that position when no current is supplied to the starter motor.

[0018] The subject matter of the invention relates to the method obtained by providing a method according to the appended independent method claim. The advantages of such a method and its embodiment, which are defined in the dependent method claims, are clearly apparent from the above description of the inventive arrangement.

[0019] The invention also relates to a computer program, a computer program product, an electronic control unit and a motor vehicle according to the claims directed thereto.

[0020] Further advantageous features and advantages of the invention will become apparent from the following description. Short description of the drawings

[0021] With reference to the accompanying drawings, a specific description will now be given of the exemplary embodiments of the invention.

[0022] They show: Fig. 1 is a highly schematic representation essentially showing how a starter motor is connected to an internal combustion engine of a motor vehicle in order to describe the problem to be solved by an arrangement according to the present invention, Fig. 2 is a schematic diagram showing an arrangement according to a first embodiment of the invention, Fig. 3 is a schematic diagram showing part of an arrangement according to a second embodiment of the invention, Fig. 4 is a flowchart showing a method according to an embodiment of the invention, and Fig. 5 a schematic representation of an electronic control unit for implementing a method according to the invention. Detailed description of embodiments of the invention

[0023] Fig. Figure 1 shows, highly schematically, how a starter motor 1 is connected to or integrated into an internal combustion engine 2 in a motor vehicle 3. The electrical energy for operating the starter motor is provided by the motor vehicle's electric batteries 4 by connecting them to their opposite poles 5, 6. It is also shown how a generator 7 is connected in parallel with the starter motor to generate electrical energy for charging the batteries 4 and / or for operating loads, such as headlights, of the vehicle.

[0024] To start the starter motor 1 and thus the engine 2, an ignition lock 8 must be actuated. It is shown how this is done by first closing an ignition switch 11 and then a switch 9, which sends a starter control signal, a so-called 50 signal, to an electronic control unit 10 of the motor vehicle. The electronic control unit 10 is configured to transmit the starter control signal or the so-called 50 signal to the starter motor 1 via a connecting line 12 between the electronic control unit 10 and the starter motor 1, which is required for its starting process. What was described above with reference to Fig. 1 represents a common design in motor vehicles.

[0025] An arrangement and a method according to a first embodiment of the invention are described below with reference also to Fig. 2. The arrangement according to the invention is designed such that a current to the starter motor is interrupted when no current is to flow to the starter motor, i.e. when no S0 signal is present at the input of the starter motor. A voltage above a certain level, such as 3 V, is present on the connecting line 12 between the electronic control unit 10 and the starter motor 1 when the starter control signal (S0 signal) is present. For this purpose, the arrangement comprises a sensor 13 in the form of a voltmeter, which is configured to measure the voltage on the line 12 in order to determine whether or not such a starter control signal is present. The voltmeter is assigned a first logic element 14, which is configured to send a logical 1 to a logical AND gate 15 as long as the absence of such a starter control signal is detected.This also means that a logic 0 is sent to AND gate 15 whenever a voltage above this level is measured by sensor 13. To achieve this, an element 45 compares the value of the measured voltage with the level. However, the signal sent by the first logic element 14 is forwarded to AND gate 15 with a certain delay, e.g., 0.1 s or 0.2 s, so that it is only validated if the presence or absence of the start-up control signal measured by the sensor is continuous for a predetermined period of time. This is indicated by a delay element 16.

[0026] The arrangement according to the invention further comprises an element 17 configured to measure a value indicating the current supplied to the starter motor 1. This is done here by measuring the current in the line 18 for supplying electrical energy to the starter motor 1, for example by a shunt measurement of a voltage in this line or by a Hall element arranged in this line. It is shown how the measured current value can be sent to an amplifier 19 and then on to a second logic element 20. This is configured to send a logic 1 to the AND gate 15 if a current supplied to the starter motor is detected to be above a minimum level. To achieve this, an element 21 compares the value of the current measured by the element 17 with the minimum level, which, for example,20 A, and only sends such a logic 1 on line 46 to the AND gate 15 if it is determined that the current is above the minimum level for a predetermined period of time, such as 0.1 s or 0.2 s, which is indicated by a delay element 22. Accordingly, a logic 1 will be present at the output 23 of the AND gate if a current above the minimum level is supplied to the starter motor and at the same time no start control signal is sent to the starter motor.

[0027] The arrangement also includes a device configured to interrupt an abnormal current supplied to the starter motor, which in this case is a current supplied to the starter motor when no current is to be supplied to it, more precisely when the condition leading to a logic 1 at the output of the AND gate 15 is met. The device 24 includes a current interruption device 25 arranged in the line 18, which connects the starter motor with the electric batteries 4 in a position parallel to the generator 7, so that the connection of the generator to the electric batteries is not interrupted when a current to the starter motor is interrupted. This means here that a pyrotechnic interrupter configured to be triggered by a logic 1 at the output 23 of the AND gate 15 permanently interrupts a current supplied to the starter motor upon such triggering.Other alternatives to such interrupting devices are a circuit breaker or a semiconductor switch controlled by the output signal from the gate 15 to interrupt a current supplied to the starter motor.

[0028] It also shows how the arrangement can be provided with an electrical energy source 26, here in the form of a diode 27 with a capacitor 28 for storing electrical energy. This is configured to supply electrical energy to the device 24 (in fact, all components with reference numerals 13 to 17, 19 to 22, and 45 are supplied with electrical energy via this source, as indicated by their connection to the AND gate 15) in order to ensure the interruption of such anomalous current in the event of a failure of the connection between the motor vehicle's electrical batteries and the device 24.

[0029] Fig. Figure 3 shows schematically how an element configured to measure a quantity indicative of the current supplied to the starter motor can be realized in an arrangement according to a second embodiment of the invention. Fig. Figure 3 shows in simplified form the structure of the connection of the starter motor 1 to an electrical energy source, which is indicated by the two poles 5, 6 connected to electrical batteries. This structure also applies to the Fig. 2. A starter control signal from the electronic control unit 10, present on line 12, closes a relay 30, which closes a main relay 31 to supply electrical energy to the stator 32 of the starter motor and rotate its rotor 33. When a current is supplied to the starter motor, this results in a voltage at a position 34 on the supply side of the starter motor with respect to ground, so that a measurement of this voltage indicates whether or not a current is being supplied to the starter motor. Current can be supplied to the starter motor, for example, if one of the relays 30 or 31 has contacts permanently connected by welding. A voltage measuring element 35 is arranged to measure this voltage at position 34. A second logic element 38, in this case, sends a logic 1 to an AND gate on line 46, as shown in Fig. 2, if a comparison element 36 were to determine that the voltage in position 34 is above a predetermined level, such as 1 V, for a predetermined period of time, such as 0.2 s, as indicated by box 37. It would also be possible to connect such a magnitude measuring element according to the two embodiments shown and its output to an OR gate for sending a logical 1 on to the AND gate when one of the magnitude measuring elements has performed a measurement which results in a logical 1 at its output.

[0030] Fig. 4 shows a flowchart of a method according to an embodiment of the present invention for protecting against abnormal currents in a starter motor circuit of a starter motor connected to an internal combustion engine of a motor vehicle. The method begins with a step S1 for measuring the current supplied to the starter motor. A step S2 for detecting the presence of a starter control signal sent to the starter motor is executed in parallel with step S1. The question "Is current being supplied to the starter motor?" is asked in a step S3, and the question "Is there no starter control signal sent to the starter motor?" is asked in a step S4. In a step S5, the question "Were both questions in steps S3 and S4 answered with yes?" is asked. If the answer to this question is yes, the method continues with a step S6 for interrupting the current supplied to the starter motor.

[0031] A computer program code for implementing a method according to the invention is advantageously comprised in a computer program that can be read into the internal memory of a computer, e.g., the internal memory of an electronic control unit of a motor vehicle. Such a computer program is advantageously provided via a computer program product comprising a computer-readable data storage medium on which the computer program is stored. This data storage medium is, e.g., an optical data storage medium in the form of a CD-ROM disc, a DVD disc, etc., a magnetic data storage medium in the form of a hard disk, a floppy disk, a cassette tape, etc., or a flash memory or a memory of the ROM, PROM, EPROM, or EEPROM type. Fig. Figure 5 shows a highly schematic representation of an electronic control unit 44 having an execution device 40, e.g., a central processing unit (CPU), for executing computer software. The execution device 40 communicates with a memory 41, e.g., of the RAM type, via a data bus 42. The control unit 44 also comprises a non-volatile data storage medium 43, e.g., in the form of a flash memory or a memory of the ROM, PROM, EPROM, or EEPROM type. The execution device 40 communicates with the data storage medium 43 via the data bus 42. The data storage medium 43 contains a computer program with computer program code for carrying out a method according to the invention, e.g., according to the Fig. 4 illustrated embodiment.

[0032] The invention is of course in no way limited to the embodiments described above, since many possibilities for modifying them will be obvious to those skilled in the art without departing from the scope of protection defined in the appended claims.

[0033] Although shown separately in the figures, the sensor and the current measuring element with logic are preferably integrated on a printed circuit board and combined with the current interruption device.

Claims

[1] Arrangement for protection against abnormal currents in a starter motor circuit of a starter motor (1) connected to an internal combustion engine (2) of a motor vehicle (3), the arrangement comprising a device (24) configured to interrupt an abnormal current supplied to the starter motor, the arrangement further comprising - a sensor (13) configured to detect the presence of a starter control signal sent to the starter motor, - an element (17, 35) configured to measure a quantity indicative of the current supplied to the starter motor, and - a control unit configured to determine, on the basis of information from the sensor and the element, that an abnormal current is being supplied to the starter motor (1) under the condition that a current above a minimum level has been detected by measurement by the element (17, 35) and the sensor (13) has simultaneously detected an absence of the starter control signal, and, if this condition is met, to control the device (24) such that it interrupts the current supplied to the starter motor, the arrangement being configured to be arranged in a motor vehicle (3) having a generator (7) connected in parallel with the starter motor (1), characterized by that the device (24) is configured to interrupt such an abnormal current at a point within a line (18) which connects the starter motor (1) in parallel with the generator (7). [2] Arrangement according to claim 1, characterized byin that the control unit is configured to consider a current above a minimum level as being measured by the element (17, 35) only if such a current is measured to be continuously present for a predetermined period of time, such as at least 0.1 s. [3] Arrangement according to one of the preceding claims, characterized byin that the control unit comprises a first logic element (14) connected to the sensor (13) and configured to send a logic 1 to a logic AND gate (15) as long as the absence of the starter control signal is detected, and a second logic element (20, 36) connected to the magnitude measuring element (17, 35) and configured to send a logic 1 to the AND gate (15) when a current supplied to the starter motor (1) above the minimum level is detected by measurement by the element (17, 35), and in that the device (24) is configured to be triggered by a logic 1 at the output (23) of the AND gate in order to interrupt an abnormal current supplied to the starter motor. [4] Arrangement according to one of the preceding claims, characterized byin that the device (24) comprises a current interruption device (25) arranged in a line connecting the starter motor to a source of electrical energy, such as electric batteries (4) of the motor vehicle (3), and configured to be triggered to interrupt an abnormal current supplied to the starter motor in the line, such as a pyrotechnic interrupter, a circuit breaker or a semiconductor switch, such as a transistor. [5] Arrangement according to one of the preceding claims, characterized by in that it comprises an electrical energy source (26) configured to supply electrical energy to the device (24) to ensure the interruption of such anomalous current in the event of failure of a connection between electrical batteries (4) of a motor vehicle (3) and the device (24). [6] Arrangement according to one of the preceding claims, characterized byin that the magnitude measuring element (17) is configured to measure the current in a line (18) for supplying electrical energy to the starter motor (1), for example by a shunt measurement of a voltage in the line or by a Hall element arranged in the line. [7] Arrangement according to one of claims 1 to 5, characterized by in that the magnitude measuring element (35) is configured to measure the voltage at a position (34) in the starter motor circuit on the supply side of a starter motor (1) with respect to ground as a quantity indicative of the current supplied to the starter motor. [8] Method for protection against abnormal currents in a starter motor circuit of a starter motor (1) connected to an internal combustion engine (2) of a motor vehicle (3), comprising the following steps a) detecting the presence of a starter control signal sent to the starter motor, b) measuring a quantity indicating the current supplied to the starter motor, c) determining that an abnormal current is being supplied to the starter motor, provided that the measurement has detected a current above a minimum level and, at the same time, that the starter control signal is absent, and d) interrupting the current supplied to the starter motor when this condition is met, the method being carried out in a motor vehicle (3) having a generator (7) connected in parallel to the starter motor (1), characterized by that in step d) such an abnormal current is interrupted in a position within a line (18) which connects the starter motor (1) in parallel with the generator (7). [9] Method according to claim 8, characterized bythat in step b) a quantity which indicates the current supplied to the starter motor (1) is measured by measuring the current in a line (18) which supplies electrical energy to the starter motor, for example indirectly by a shunt measurement of a voltage or directly by a Hall element. [10] Method according to claim 8, characterized by that in step b) a quantity indicating the current supplied to the starter motor (1) is measured by measuring the voltage with respect to ground at a position (34) in the starter motor circuit on the supply side of the starter motor. [11] Method according to one of claims 8 to 10, characterized by that in step c) it is determined that a current above a minimum level has been detected by the measurement in step b) only if such a current is measured which is continuously present over a predetermined period of time, such as at least 0.1 s. [12] A computer program comprising computer program code for causing a computer to implement a method according to any one of claims 8 to 11 when the computer program is executed by a computer. [13] A computer program product comprising a non-volatile data storage medium which is readable by a computer and on which the program code of a computer program according to claim 12 is stored. [14] Electronic control unit with an execution device (40), a memory (41) connected to the execution device and a non-volatile data storage medium (43) connected to the execution device (40) on which the computer program code of a computer program according to claim 12 is stored. [15] Motor vehicle, in particular a wheeled vehicle such as a lorry or a bus, characterized by that it comprises an electronic control unit (44) according to claim 14.

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