EP0279042B1 - Arrangement for protecting relay contacts - Google Patents
Arrangement for protecting relay contacts Download PDFInfo
- Publication number
- EP0279042B1 EP0279042B1 EP19870117879 EP87117879A EP0279042B1 EP 0279042 B1 EP0279042 B1 EP 0279042B1 EP 19870117879 EP19870117879 EP 19870117879 EP 87117879 A EP87117879 A EP 87117879A EP 0279042 B1 EP0279042 B1 EP 0279042B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- switching
- switched
- switching device
- semiconductor module
- glow plug
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02N—STARTING OF COMBUSTION ENGINES; STARTING AIDS FOR SUCH ENGINES, NOT OTHERWISE PROVIDED FOR
- F02N19/00—Starting aids for combustion engines, not otherwise provided for
- F02N19/02—Aiding engine start by thermal means, e.g. using lighted wicks
- F02N19/04—Aiding engine start by thermal means, e.g. using lighted wicks by heating of fluids used in engines
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
- F02P19/00—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition
- F02P19/02—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs
- F02P19/021—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs characterised by power delivery controls
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
- F02P19/00—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition
- F02P19/02—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs
- F02P19/021—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs characterised by power delivery controls
- F02P19/022—Incandescent ignition, e.g. during starting of internal combustion engines; Combination of incandescent and spark ignition electric, e.g. layout of circuits of apparatus having glowing plugs characterised by power delivery controls using intermittent current supply
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
- H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
- H01H9/54—Circuit arrangements not adapted to a particular application of the switching device and for which no provision exists elsewhere
- H01H9/541—Contacts shunted by semiconductor devices
- H01H9/542—Contacts shunted by static switch means
Definitions
- the invention relates to a device for protecting relay contacts, in particular in motor vehicles, with a current source, with an electrical consumer, with a first switching device for connecting the electrical consumer to the current source via a resistor, with a second switching device which is designed as a relay for direct connection of the consumer to the power source and to a time switching device by means of which the first switching device can be switched on before the second switching device.
- Such devices can e.g. B. for heating glow plugs via a heating current, in particular from the starter battery of motor vehicles.
- the glow plugs promote the ignition of the diesel fuel injected into the cold self-igniting internal combustion engine.
- the heating current can reach orders of magnitude up to 300 amperes and larger.
- Such a device is known from DE-OS 29 07 772, which is used as a preheating device for self-igniting internal combustion engines and in which to protect relay contacts and glow plugs, the glow plugs as electrical consumers during a first heating period via a first switching device which is designed as a relay , and connected via a series resistor to the power source and thereby supplied with a correspondingly low heating current. Only after a predetermined period of time from a few seconds to a few minutes is the glow plug directly connected to the power source via a second switching device.
- the known device has disadvantages.
- the glow plugs By supplying the glow plugs with a low heating current during a first heating period, the glow plugs heat up more slowly than in the case of preheating devices which do not have the measures of the previously known device. This means that the waiting time of the machine operator until the self-igniting internal combustion engine can be started increases noticeably compared to preheating devices which have no means for protecting relay contacts. This leads to a loss of comfort when operating the self-igniting internal combustion engine.
- the series resistor is additionally required in the known device.
- Such a series resistor with a correspondingly high load capacity is expensive to procure and takes up space, for. B. in the engine compartment of motor vehicles. This means that the previously known device can only be produced in a complex and expensive manner.
- the invention has for its object to provide a device which is simpler and less expensive to produce than the prior art and which, while protecting relay contacts, enables the electrical consumer to be supplied with the full supply voltage.
- the first switching device is a semiconductor component and in that the resistance is the internal resistance of the switching path of the semiconductor component.
- the first switching device as a semiconductor component, unlike in the prior art, it is not possible for relay contacts of a first switching device to be overloaded because there are no relay contacts.
- the internal resistance of the switching path of the semiconductor component is small compared to the series resistor of the previously known device, so that the time until the glow plug heats up can be shortened considerably compared to the previously known device.
- no additional expensive and space-consuming series resistor is required.
- the device according to the invention also has the advantage that the first period, during which the first switching device is switched on and the second switching device is still switched off, can be reduced to times of the order of 1 ms, inter alia, due to the shorter switching times of the semiconductor component.
- a field-effect transistor in particular a MOS-FET
- MOS-FET MOS-FET
- a bipolar transistor or a so-called gate turn-off thyristor can also be used as a semiconductor component. Gate turn-off thyristors are switching elements whose switching on and off is also possible during the current flow.
- a monitoring device which measures the voltage drop across the internal resistance of the switching path of the semiconductor component and compares it with predetermined threshold values when the first switching device is switched on and the second switching device is switched off, the Monitoring device switches off the switching devices when the value falls below a first threshold value and / or supplies a first error signal to a first display device and / or the monitoring device switches off the switching devices and / or supplies a second error signal to a second display device when a second threshold value is exceeded.
- MOS-FET with an integrated monitoring device, such as is currently freely available, can be used, so that the additional effort for the construction of the monitoring device is low.
- the time switch device and / or the monitoring device can be designed as part of a microcomputer.
- the time switching device in such a way that it switches the switching devices on and off periodically, in particular at a constant frequency and depending on the supply voltage and the glow plug temperature of variable switch-on time, because this measure compensates for supply voltage fluctuations and controls the glow plug temperature It is possible to change the switch-on times of the first and second switching devices.
- this measure when this measure is used, the advantages of the preheating device according to the invention become particularly clear because the frequent switching on and off of the first and second switching devices with frequencies of z. B. 2 Hz, the load on the relay contacts is particularly high.
- the relay contacts can have burned down after only about 8 months of operation of a motor vehicle with a self-igniting internal combustion engine and over 2 million actuations of the relay contacts, so that attempts to start the internal combustion engine are no longer possible, as tests have shown.
- the preheating circuit is a current source (B), which can be designed as a motor vehicle battery, a preheating switch (VS), which can be designed as the first catch of a preheating switch of a motor vehicle, an electrical consumer (V), which is designed as a glow plug and a first switching device, which is designed as a semiconductor component (HL), in particular as a MOS-FET, and a second switching device, which is designed as a relay contact set (RK) of an electromagnetic relay.
- the semiconductor component (HL) and the relay contact set (RK) are connected in parallel in the glow plug circuit.
- the semiconductor component (HL) and the electromagnetic relay (RK, RS) can be switched on and off by a time switch, which is designed as part of a microcomputer (MC).
- the microcomputer (MC) is connected to the power source (B) in a known manner for power supply.
- an NPN driver transistor (TR1) is provided, the base of which can be controlled by the output signal of the microcomputer (MC) and the emitter of which is connected to the negative pole of the current source (B) and its Collector is connected to the positive pole of the power source (B) via the electromagnetic relay coil (RS).
- the semiconductor switch (HL) can also be controlled by the microcomputer (MC) via a voltage doubler circuit (SPV).
- the voltage doubler circuit (SPV) is required because an N-channel MOS-FET is used here as the semiconductor component and the potential at the gate input (G) must always be greater than the potential at the SOURCE- to control the MOS-FET. Port (S).
- the first Zener diode (Z1) and the second Zener diode (Z2) also serve to protect the MOS-FET (HL) and the NPN transistor (TR1).
- the first Zener diode (Z1) protects the NPN transistor (TR1) against overvoltage and is reverse polarity protection.
- the second Zener diode (Z2) serves to limit the voltage at the GATE input compared to the voltage at the SOURCE connection of the MOS-FET (HL). This voltage difference must not exceed a value specified by the design of the MOS-FET.
- the SOURCE connection of the MOS-FET (HL) is thus via the glow plug (V) with the negative coil of the power source (B) and via the DRAIN connection (D) and the preheat switch (VS) is conductively connected to the positive pole of the current source (B).
- the potential or the voltage drop (UDS) at the switching path of the MOS-FET (HL) is tapped between the SOURCE connection (S) and the DRAIN connection (D) and an analog-to-digital converter (ADC), which can also be designed as a comparator.
- the output signal of the analog-to-digital converter (ADC) is sent to the microcomputer (MC) to determine contact actuation, line breaks and short circuits.
- the analog-to-digital converter (ADC) is part of a monitoring device, the other part of which is formed in the microcomputer (MC).
- the monitoring device compares the voltage drop (UDS) across the internal resistance of the switching path of the semiconductor component (HL) with predetermined threshold values when the first switching device, i.e. the MOS-FET (HL), is switched on and the second switching device, i.e. the electromagnetic relay, is switched off is. If the voltage drop (UDS) falls below a first threshold value, the monitoring device switches off the first switching device (HL) and prevents the second switching device (RK) from being switched on and outputs a first error signal to a first display device (FL1), which is shown in FIG simple indicator lamp is shown.
- the monitoring device switches the first switching device (HL) off and prevents the second switching device (RK) from being switched on, and a second error signal is delivered to a second display device (FL2), which is also in 1 is shown as a simple indicator lamp.
- the error signals can also be used to control other devices on the self-igniting internal combustion engine or the motor vehicle.
- the glow plug (VS) is in the open position shown in FIG. 1. Then the entire preheating device according to the invention is de-energized and no potential differences can be measured. If the preheating switch (VS) is now closed, the first switching device (HL) and the second switching device (RK) remain open from this point in time, which is marked with the time zero in FIG. 2, until the point in time (T1) Position so that no current can flow through the glow plug (V). A potential is then measured on the switching path of the semiconductor switch as a voltage drop (UDS) that corresponds to the battery voltage (UB) of the current source (B).
- UDS voltage drop
- the semiconductor switch (HL) is now switched on at time (T1), the current flow from the positive pole of the battery via the glow plug (VS), the switching path of the semiconductor switch (HL) and the glow plug (V) to the negative pole of the current source (B) is made possible .
- the glow plug (V) is in perfect electrical condition, then a small amount (U1) of the total voltage applied drops across the switching path of the semiconductor switch (HL). This voltage drop (U1) can be measured over the entire period (T), which extends from T1 to T2 and in which the semiconductor switch (HL) is switched on and the second switching device (RK) is switched off.
- This voltage drop (U1) is measured by the analog-to-digital converter (ADC) and passed on in a converted form to the microcomputer (MC).
- ADC analog-to-digital converter
- the second switching device (RK) is opened so that the current flows again over the switching path of the semiconductor component (HL). Accordingly, a voltage amount (U1) drops across the switching path of the semiconductor component (HL).
- the semiconductor component (HL) is also switched off. The current flow is interrupted. The entire battery voltage (UB) is now again applied to the switching path of the semiconductor switch (HL).
- the glow plug (V) is not in perfect condition, this can be detected by the monitoring device during the period (T). If the glow plug (V) had a short circuit, the entire voltage (UB) at the switching path of the semiconductor component (HL) would drop during the period (T). This means that the measured voltage drop (UDS) would be above the first threshold value (US1) shown in FIG. 2. This increased voltage drop would be recognized by the monitoring device and a first error signal would be delivered to the first display device (FL1). At the same time, the semiconductor switch (HL) is then switched off in order to prevent the semiconductor components (HL) from being overloaded.
- the preheating device not only protects the relay contacts (RK) easily and inexpensively, but also enables the glow plug circuit to be monitored for short circuits and line interruptions in a simple manner.
- the glow plug (V) can advantageously be switched on and off periodically by the pre-glow device according to the invention.
- This has the advantage that supply voltage fluctuations and the glow plug temperature can be changed by changing the switch-on times. It is particularly advantageous to carry out this periodic switch-on and switch-off with a constant switch-on time and a switch-off time that varies depending on the supply voltage and the glow plug temperature because the clock signal required for this can be provided in a simple manner by using the microcomputer (MC). This means that the switch-on and switch-off process shown in FIG. 2 would be repeated periodically.
- the advantages of the preheating device according to the invention are particularly noticeable because the preheating device according to the invention means that the relay contacts (RK) are hardly noticeable.
- V glow plug
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Electronic Switches (AREA)
- Relay Circuits (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
- Control Of Resistance Heating (AREA)
- Mechanisms For Operating Contacts (AREA)
- Direct Current Feeding And Distribution (AREA)
Description
Die Erfindung betrifft eine Vorrichtung zum Schonen von Relaiskontakten, insbesondere in Kraftfahrzeugen, mit einer Stromquelle, mit einem elektrischen Verbraucher, mit einer ersten Schalteinrichtung zum Verbinden des elektrischen Verbrauchers mit der Stromquelle über einen Widerstand, mit einer zweiten Schalteinrichtung, die als Relais ausgebildet ist zum direkten Verbinden des Verbrauchers mit der Stromquelle und mit einer Zeitschalteinrichtung, durch die die erste Schalteinrichtung vor der zweiten Schalteinrichtung einschaltbar ist.The invention relates to a device for protecting relay contacts, in particular in motor vehicles, with a current source, with an electrical consumer, with a first switching device for connecting the electrical consumer to the current source via a resistor, with a second switching device which is designed as a relay for direct connection of the consumer to the power source and to a time switching device by means of which the first switching device can be switched on before the second switching device.
Solche Vorrichtungen können z. B. zur Aufheizung von Glühkerzen über einen Heizstrom, insbesondere aus der Starterbatterie von Kraftfahrzeugen verwendet werden. Die Glühkerzen fördern die Zündung des in die kalte selbstzündende Brennkraftmaschine eingespritzten Dieselkraftstoffs. Der Heizstrom kann dabei Größenordnungen bis zu 300 Ampere und größer erreichen.Such devices can e.g. B. for heating glow plugs via a heating current, in particular from the starter battery of motor vehicles. The glow plugs promote the ignition of the diesel fuel injected into the cold self-igniting internal combustion engine. The heating current can reach orders of magnitude up to 300 amperes and larger.
Eine derartige Vorrichtung ist aus der DE-OS 29 07 772 vorbekannt, die als Vorglüheinrichtung für selbstzündende Brennkraftmaschinen verwendet wird und bei der zur Schonung von Relaiskontakten und Glühkerzen die Glühkerzen als elektrische Verbraucher während einer ersten Heizperiode über eine erste Schalteinrichtung, die als Relais ausgebildet ist, und über einen Vorwiderstand mit der Stromquelle verbunden und dadurch mit einem entsprechend geringen Heizstrom versorgt werden. Erst nach einer vorgegebenen Zeitdauer von einigen Sekunden bis zu einigen Minuten wird die Glühkerze über eine zweite Schalteinrichtung direkt mit der Stromquelle leitend verbunden.Such a device is known from DE-OS 29 07 772, which is used as a preheating device for self-igniting internal combustion engines and in which to protect relay contacts and glow plugs, the glow plugs as electrical consumers during a first heating period via a first switching device which is designed as a relay , and connected via a series resistor to the power source and thereby supplied with a correspondingly low heating current. Only after a predetermined period of time from a few seconds to a few minutes is the glow plug directly connected to the power source via a second switching device.
Die vorbekannte Vorrichtung hat jedoch Nachteile. Durch die Versorgung der Glühkerzen mit einem geringen Heizstrom während einer ersten Heizperiode heizen sich die Glühkerzen langsamer auf, als bei Vorglüheinrichtungen, die die Maßnahmen der vorbekannten Vorrichtung nicht aufweisen. Das heißt, die Wartezeit des Maschinenbedieners bis zum möglichen Anlassen der selbstzündenden Brennkraftmaschine verlängert sich merklich gegenüber Vorglüheinrichtungen, die keine Mittel zur Schonung von Relaiskontakten aufweisen. Dies führt zu einer Komforteinbuße bei der Bedienung der selbstzündenden Brennkraftmaschine.However, the known device has disadvantages. By supplying the glow plugs with a low heating current during a first heating period, the glow plugs heat up more slowly than in the case of preheating devices which do not have the measures of the previously known device. This means that the waiting time of the machine operator until the self-igniting internal combustion engine can be started increases noticeably compared to preheating devices which have no means for protecting relay contacts. This leads to a loss of comfort when operating the self-igniting internal combustion engine.
Weiterhin ist bei der vorbekannten Vorrichtung der Vorwiderstand zusätzlich erforderlich. Ein solcher Vorwiderstand mit entsprechend hoher Belastbarkeit ist teuer in der Beschaffung und beansprucht einen Bauraum, z. B. im Motorraum von Kraftfahrzeugen. Das heißt, die vorbekannte Vorrichtung ist nur aufwendig und teuer herstellbar.Furthermore, the series resistor is additionally required in the known device. Such a series resistor with a correspondingly high load capacity is expensive to procure and takes up space, for. B. in the engine compartment of motor vehicles. This means that the previously known device can only be produced in a complex and expensive manner.
Die Erfindung hat die Aufgabe, eine Vorrichtung zu schaffen, die gegenüber dem Vorbekannten einfacher und kostengünstiger herstellbar ist und die bei gleichzeitiger Schonung von Relaiskontakten die Versorgung des elektrischen Verbrauchers mit der vollen Versorgungsspannung ermöglicht.The invention has for its object to provide a device which is simpler and less expensive to produce than the prior art and which, while protecting relay contacts, enables the electrical consumer to be supplied with the full supply voltage.
Diese Aufgabe wird dadurch gelöst, daß die erste Schalteinrichtung ein Halbleiter-Bauelement ist und daß der Widerstand der Innenwiderstand der Schaltstrecke des Halbleiter-Bauelements ist.This object is achieved in that the first switching device is a semiconductor component and in that the resistance is the internal resistance of the switching path of the semiconductor component.
Durch die Ausbildung der ersten Schalteinrichtung als Halbleiter-Bauelement ist es, anders als beim Vorbekannten, nicht möglich, daß Relaiskontakte einer ersten Schalteinrichtung überbelastet werden, weil keine Relaiskontakte vorhanden sind. Der Innenwiderstand der Schaltstrecke des Halbleiter-Bauelements ist verglichen mit dem Vorwiderstand der vorbekannten Vorrichtung klein, so daß die Zeitdauer bis zur Aufheizung der Glühkerze gegenüber dem Vorbekannten wesentlich verkürzt werden kann. Es ist, anders als beim Vorbekannten, kein zusätzlicher teurer und platzbeanspruchender Vorwiderstand erforderlich. Bei Anwendung dieser Maßnahme ist dennoch die Schonung der Relaiskontakte der zweiten Schalteinrichtung sichergestellt, weil beim Schließen der Relaiskontakte kein Lichtbogen gebildet wird.By designing the first switching device as a semiconductor component, unlike in the prior art, it is not possible for relay contacts of a first switching device to be overloaded because there are no relay contacts. The internal resistance of the switching path of the semiconductor component is small compared to the series resistor of the previously known device, so that the time until the glow plug heats up can be shortened considerably compared to the previously known device. In contrast to the prior art, no additional expensive and space-consuming series resistor is required. When this measure is used, the protection of the relay contacts of the second switching device is nevertheless ensured, because no arc is formed when the relay contacts are closed.
Die erfindungsgemäße Vorrichtung hat weiterhin den Vorteil, daß unter anderem aufgrund der kürzeren Schaltzeiten des Halbleiter-Bauelements die erste Periode, während der die erste Schalteinrichtung eingeschaltet und die zweite Schalteinrichtung noch ausgeschaltet ist, auf Zeiten von der Größenordnung 1 ms verringert werden können. Dies hat zur Folge, daß z. B. die Zeitdauer bis zur vollständigen Aufheizung der Glühkerze gegenüber dem Vorbekannten zusätzlich verkürzt werden kann und im wesentlichen der Zeitdauer bei ständiger direkter Speisung der Glühkerze aus der Stromquelle entspricht.The device according to the invention also has the advantage that the first period, during which the first switching device is switched on and the second switching device is still switched off, can be reduced to times of the order of 1 ms, inter alia, due to the shorter switching times of the semiconductor component. This has the consequence that z. B. the time to complete heating of the glow plug can be shortened compared to the prior art and essentially corresponds to the time period with constant direct supply of the glow plug from the power source.
Es ist vorteilhaft, als Halbleiter-Bauelement einen Feldeffekt-Transistor, insbesondere einen MOS-FET, zu verwenden, weil der Innenwiderstand der Schaltstrecke genügend klein ist, um die am Feldeffekt-Transistor sich bildende Verlustwärme ohne weitere Hilfsmittel, wie z. B. Kühlkörper, an die Umgebung abzuführen. Man kann auch als Halbleiter-Bauelement einen bipolaren Transistor oder einen sogenannten Gate-Turn-Off-Thyristor verwenden. Gate-Turn-Off-Thyristoren sind dabei Schaltelemente, deren Ein- und Ausschaltung auch während des Stromflusses möglich ist.It is advantageous to use a field-effect transistor, in particular a MOS-FET, as a semiconductor component, because the internal resistance of the switching path is sufficiently small to withstand the heat loss which forms on the field-effect transistor without further aids, such as, for. B. heat sink to dissipate to the environment. A bipolar transistor or a so-called gate turn-off thyristor can also be used as a semiconductor component. Gate turn-off thyristors are switching elements whose switching on and off is also possible during the current flow.
Es ist besonders vorteilhaft, eine Überwachungsvorrichtung vorzusehen, die den Spannungsabfall an dem Innenwiderstand der Schaltstrecke des Halbleiter-Bauelements mißt und mit vorgegebenen Schwellwerten vergleicht, wenn die erste Schalteinrichtung eingeschaltet und die zweite Schalteinrichtung ausgeschaltet ist, wobei die Überwachungseinrichtung bei Unterschreiten eines ersten Schwellwerts die Schalteinrichtungen ausschaltet und/oder ein erstes Fehlersignal an eine erste Anzeigeeinrichtung liefert und/oder die Überwachungseinrichtung beim Überschreiten eines zweiten Schwellwerts die Schalteinrichtungen ausschaltet und/oder ein zweites Fehlersignal an eine zweite Anzeigeeinrichtung liefert. Durch diese Maßnahmen ist die Kontrolle des Heizstromkreises auf Kurzschlüsse und Stromkreisunterbrechungen möglich.It is particularly advantageous to provide a monitoring device which measures the voltage drop across the internal resistance of the switching path of the semiconductor component and compares it with predetermined threshold values when the first switching device is switched on and the second switching device is switched off, the Monitoring device switches off the switching devices when the value falls below a first threshold value and / or supplies a first error signal to a first display device and / or the monitoring device switches off the switching devices and / or supplies a second error signal to a second display device when a second threshold value is exceeded. These measures enable the heating circuit to be checked for short circuits and circuit breaks.
In diesem Fall kann auch ein MOS-FET mit integrierter Überwachungseinrichtung, wie er zur Zeit frei käuflich ist, verwendet werden, so daß der zusätzliche Aufwand für den Aufbau der Überwachungseinrichtung gering ist.In this case, a MOS-FET with an integrated monitoring device, such as is currently freely available, can be used, so that the additional effort for the construction of the monitoring device is low.
Insbesondere zur Verringerung des Schaltungsaufwandes kann man die Zeitschalteinrichtung und/oder die Überwachungseinrichtung als Teil eines Mikrorechners ausbilden.In particular in order to reduce the circuit complexity, the time switch device and / or the monitoring device can be designed as part of a microcomputer.
Um auch zum Ende der Aufheizung der Glühkerzen den Vorteil der Schonung der Relaiskontakte der zweiten Schalteinrichtung zu nutzen, ist es vorteilhaft, die Zeitschalteinrichtung derart auszubilden, daß die zweite Schalteinrichtung vor der ersten Schalteinrichtung ausschalbar ist.In order to use the advantage of protecting the relay contacts of the second switching device at the end of the heating of the glow plugs, it is advantageous to design the time switching device in such a way that the second switching device can be switched off before the first switching device.
Schließlich ist es besonders vorteilhaft, die Zeitschalteinrichtung derart auszubilden, daß sie die Schalteinrichtungen periodisch, insbesondere mit konstanter Frequenz und abhängig von der Versorgungsspannung und der Glühkerzentemperatur veränderlicher Einschaltzeit ein- und ausschaltet, weil mit dieser Maßnahme die Kompensation von Versorgungsspannungsschwankungen und die Steuerung der Glühkerzentemperatur durch Veränderung der Einschaltzeiten der ersten und zweiten Schalteinrichtung möglich ist. Insbesondere bei Anwendung dieser Maßnahme werden die Vorteile der erfindungsgemäßen Vorglüheinrichtung besonders deutlich, weil durch das häufige Ein-und Ausschalten der ersten und zweiten Schalteinrichtungen mit Frequenzen von z. B. 2 Hz die Belastung der Relaiskontakte besonders hoch ist. Ohne die Verwendung der erfindungsgemäßen Vorglüheinrichtung können die Relaiskontakte schon nach ca. 8 Monaten Betriebsdauer eines Kraftfahrzeugs mit selbstzündender Brennkraftmaschine und über 2 Millionen Betätigungen der Relaiskontakte soweit abgebrannt sein, daß ein Anlassen der Brennkraftmaschine nicht mehr möglich ist, wie Versuche gezeigt haben.Finally, it is particularly advantageous to design the time switching device in such a way that it switches the switching devices on and off periodically, in particular at a constant frequency and depending on the supply voltage and the glow plug temperature of variable switch-on time, because this measure compensates for supply voltage fluctuations and controls the glow plug temperature It is possible to change the switch-on times of the first and second switching devices. In particular when this measure is used, the advantages of the preheating device according to the invention become particularly clear because the frequent switching on and off of the first and second switching devices with frequencies of z. B. 2 Hz, the load on the relay contacts is particularly high. Without the use of the preheating device according to the invention, the relay contacts can have burned down after only about 8 months of operation of a motor vehicle with a self-igniting internal combustion engine and over 2 million actuations of the relay contacts, so that attempts to start the internal combustion engine are no longer possible, as tests have shown.
Ein Ausführungsbeispiel des Erfindungsgegenstands ist in den Zeichnungen dargestellt und wird im folgenden näher erläutert.An embodiment of the subject of the invention is shown in the drawings and is explained in more detail below.
Es zeigen
- Figur 1 schematisch eine erfindungsgemäße Vorrichtung, die als Vorglüheinrichtung für selbstzündende Brennkraftmaschinen ausgebildet ist und
- Figur 2 ein Diagramm, in dem der Spannungsabfall am Innenwiderstand des Halbleiter-Bauelements abhängig von den Einschaltzeiten der ersten und zweiten Schalteinrichtung dargestellt ist.
- Figure 1 schematically shows a device according to the invention, which is designed as a preheating device for self-igniting internal combustion engines and
- FIG. 2 shows a diagram in which the voltage drop across the internal resistance of the semiconductor component is shown as a function of the switch-on times of the first and second switching devices.
In der Figur 1 wird der Vorglühstromkreis durch eine Stromquelle (B), die als Kraftfahrzeugbatterie ausgebildet sein kann, einen Vorglühschalter (VS), der als erste Rastung eines Vorglühanlaßschalters eines Kraftfahrzeugs ausgebildet sein kann, einen elektrischen Verbraucher (V), der als Glühkerze ausgebildet ist, und eine erste Schalteinrichtung, die als Halbleiter-Bauelement (HL), insbesondere als MOS-FET ausgebildet ist und eine zweite Schalteinrichtung, die als Relaiskontaktsatz (RK) eines elektromagnetischen Relais ausgebildet ist, gebildet. Das Halbleiter-Bauelement (HL) und der Relaiskontaktsatz (RK) sind dabei in Parallelschaltung in den Glühkerzenstromkreis geschaltet.In Figure 1, the preheating circuit is a current source (B), which can be designed as a motor vehicle battery, a preheating switch (VS), which can be designed as the first catch of a preheating switch of a motor vehicle, an electrical consumer (V), which is designed as a glow plug and a first switching device, which is designed as a semiconductor component (HL), in particular as a MOS-FET, and a second switching device, which is designed as a relay contact set (RK) of an electromagnetic relay. The semiconductor component (HL) and the relay contact set (RK) are connected in parallel in the glow plug circuit.
Das Halbleiter-Bauelement (HL) und das elektromagnetische Relais (RK, RS) sind dabei durch eine Zeitschalteinrichtung ein- und ausschaltbar, die als Teil eines Mikrorechners (MC) ausgebildet ist. Der Mikrorechner (MC) ist in bekannter Art und Weise zur Stromversorgung mit der Stromquelle (B) verbunden. Zur Verstärkung des Steuerstroms des Mikrorechners (MC) und zum Schalten des elektromagnetischen Relais ist ein NPN-Treibertransistor (TR1) vorgesehen, dessen Basis durch das Ausgangssignal des Mikrorechners (MC) steuerbar ist und dessen Emitter mit dem Minuspol der Stromquelle (B) und dessen Kollektor mit dem Pluspol der Stromquelle (B) über die elektromagnetische Relaisspule (RS) verbunden ist.The semiconductor component (HL) and the electromagnetic relay (RK, RS) can be switched on and off by a time switch, which is designed as part of a microcomputer (MC). The microcomputer (MC) is connected to the power source (B) in a known manner for power supply. To amplify the control current of the microcomputer (MC) and to switch the electromagnetic relay, an NPN driver transistor (TR1) is provided, the base of which can be controlled by the output signal of the microcomputer (MC) and the emitter of which is connected to the negative pole of the current source (B) and its Collector is connected to the positive pole of the power source (B) via the electromagnetic relay coil (RS).
Der Halbleiterschalter (HL) ist ebenfalls durch den Mikrorechner (MC) über eine Spannungsverdopplerschaltung (SPV) steuerbar. Die Spannungsverdopplerschaltung (SPV) ist erforderlich, weil als Halbleiter-Bauelement hier ein N-Kanal-MOS-FET verwendet wird und zur Ansteuerung des MOS-FETs das Potential am Gate-Eingang (G) immer größer sein muß als das Potential am SOURCE-Anschluß (S).The semiconductor switch (HL) can also be controlled by the microcomputer (MC) via a voltage doubler circuit (SPV). The voltage doubler circuit (SPV) is required because an N-channel MOS-FET is used here as the semiconductor component and the potential at the gate input (G) must always be greater than the potential at the SOURCE- to control the MOS-FET. Port (S).
Dem Schutz des MOS-FETs (HL) und des NPN-Transistors (TR1) dienen auch die erste Zenerdiode (Z1) und die zweite Zenerdiode (Z2). Die erste Zenerdiode (Z1) schützt den NPN-Transistor (TR1) vor Überspannung und ist ein Verpolungsschutz. Die zweite Zenerdiode (Z2) dient zur Begrenzung der Spannung am GATE-Eingang gegenüber der Spannung am SOURCE-Anschluß des MOS-FETs (HL). Diese Spannungsdifferenz darf einen durch die Bauart des MOS-FETs vorgegebenen Wert nicht überschreiten.The first Zener diode (Z1) and the second Zener diode (Z2) also serve to protect the MOS-FET (HL) and the NPN transistor (TR1). The first Zener diode (Z1) protects the NPN transistor (TR1) against overvoltage and is reverse polarity protection. The second Zener diode (Z2) serves to limit the voltage at the GATE input compared to the voltage at the SOURCE connection of the MOS-FET (HL). This voltage difference must not exceed a value specified by the design of the MOS-FET.
Der SOURCE-Anschluß des MOS-FETs (HL) ist also über die Glühkerze (V) mit dem Minuspul der Stromquelle (B) und über den DRAIN-Anschluß (D) und den Vorglühschalter (VS) mit dem Pluspol der Stromquelle (B) leitend verbunden Das Potential oder der Spannungsabfall (UDS) an der Schaltstrecke des MOS-FETs (HL) wird zwischen SOURCE-Anschluß (S) und DRAIN-Anschluß (D) abgegriffen und einem Analog-Digital-Umsetzer (ADC) zugeführt, der aber auch als Komparator ausgebildet sein kann. Das Ausgangssignal des Analog-Digital-Umsetzers (ADC) wird zur Ermittlung von Kontaktbetätigung, Leitungsunterbrechungen und Kurzschlüssen dem Mikrorechner (MC) zugeleitet. Der Analog-Digital-Umsetzer (ADC) ist Teil einer Überwachungseinrichtung, deren anderer Teil im Mikrorechner (MC) ausgebildet ist.The SOURCE connection of the MOS-FET (HL) is thus via the glow plug (V) with the negative coil of the power source (B) and via the DRAIN connection (D) and the preheat switch (VS) is conductively connected to the positive pole of the current source (B). The potential or the voltage drop (UDS) at the switching path of the MOS-FET (HL) is tapped between the SOURCE connection (S) and the DRAIN connection (D) and an analog-to-digital converter (ADC), which can also be designed as a comparator. The output signal of the analog-to-digital converter (ADC) is sent to the microcomputer (MC) to determine contact actuation, line breaks and short circuits. The analog-to-digital converter (ADC) is part of a monitoring device, the other part of which is formed in the microcomputer (MC).
Die Überwachungseinrichtung vergleicht den Spannungsabfall (UDS) an dem Innenwiderstand der Schaltstrecke des Halbleiter-Bauelements (HL) mit vorgegebenen Schwellwerten, wenn die erste Schalteinrichtung, also der MOS-FET (HL), eingeschaltet und die zweite Schalteinrichung, also das elektromagnetische Relais, ausgeschaltet ist. Unterschreitet der Spannungsabfall (UDS) einen ersten Schwellwert, so schaltet die Überwachungseinrichtung die erste Schalteinrichtung (HL) aus und verhindert das Einschalten der zweiten Schalteinrichtung (RK) und gibt ein erstes Fehlersignal an eine erste Anzeigeeinrichtung (FL1), die in der Figur 1 als einfache Anzeigelampe dargestellt ist. Überschreitet der Spannungsabfall (UDS) einen zweiten Schwellwert, so schaltet die Überwachungseinrichtung die erste Schalteinrichtung (HL) aus und verhindert das Einschalten der zweiten Schalteinrichtung (RK), und es wird ein zweites Fehlersignal an eine zweite Anzeigeeinrichtung (FL2) geliefert, die ebenfalls in der Figur 1 als einfache Anzeigelampe dargestellt ist. Die Fehlersignale können jedoch auch zur Steuerung weiterer Einrichtungen an der selbstzündenden Brennkraftmaschine oder des Kraftfahrzeugs benutzt werden.The monitoring device compares the voltage drop (UDS) across the internal resistance of the switching path of the semiconductor component (HL) with predetermined threshold values when the first switching device, i.e. the MOS-FET (HL), is switched on and the second switching device, i.e. the electromagnetic relay, is switched off is. If the voltage drop (UDS) falls below a first threshold value, the monitoring device switches off the first switching device (HL) and prevents the second switching device (RK) from being switched on and outputs a first error signal to a first display device (FL1), which is shown in FIG simple indicator lamp is shown. If the voltage drop (UDS) exceeds a second threshold value, the monitoring device switches the first switching device (HL) off and prevents the second switching device (RK) from being switched on, and a second error signal is delivered to a second display device (FL2), which is also in 1 is shown as a simple indicator lamp. However, the error signals can also be used to control other devices on the self-igniting internal combustion engine or the motor vehicle.
Die Funktion der erfindungsgemäßen Vorglüheinrichtung nach der Figur 1 wird nun anhand der Figur 2 näher erläutert:The function of the preheating device according to the invention according to FIG. 1 will now be explained in more detail with reference to FIG. 2:
Zu Beginn befindet sich der Vorglühschalter (VS) in der in der Figur 1 dargestellten geöffneten Stellung. Dann ist die gesamte erfindungsgemäße Vorglüheinrichtung stromlos, und es sind keine Potentialunterschiede meßbar. Wird nun der Vorglühschalter (VS) geschlossen, so verbleiben die erste Schalteinrichtung (HL) und die zweite Schalteinrichtung (RK) von diesem Zeitpunkt an, der mit der Zeit Null in der Figur 2 gekennzeichnet ist, bis zum Zeitpunkt (T1) in der geöffneten Stellung, so daß kein Strom durch die Glühkerze (V) fließen kann. An der Schaltstrecke des Halbleiter-Schalters wird dann als Spannungsabfall (UDS) ein Potential gemessen, daß der Batteriespannung (UB) der Stromquelle (B) entspricht.At the beginning, the glow plug (VS) is in the open position shown in FIG. 1. Then the entire preheating device according to the invention is de-energized and no potential differences can be measured. If the preheating switch (VS) is now closed, the first switching device (HL) and the second switching device (RK) remain open from this point in time, which is marked with the time zero in FIG. 2, until the point in time (T1) Position so that no current can flow through the glow plug (V). A potential is then measured on the switching path of the semiconductor switch as a voltage drop (UDS) that corresponds to the battery voltage (UB) of the current source (B).
Wird nun zum Zeitpunkt (T1) der Halbleiterschalter (HL) eingeschaltet, so wird der Stromfluß vom Pluspol der Batterie über den Vorglühschalter (VS), die Schaltstrecke des Halbleiterschalters (HL) und die Glühkerze (V) zum Minuspol der Stromquelle (B) ermöglicht. Ist die Glühkerze (V) in elektrisch einwandfreiem Zustand, so fällt an der Schaltstrecke des Halbleiterschalters (HL) ein geringer Betrag (U1) der gesamten anliegenden Spannung ab. Dieser Spannungsabfall (U1) ist über den gesamten Zeitraum (T), der sich von T1 bis T2 erstreckt und in dem der Halbleiterschalter (HL) eingeschaltet und die zweite Schalteinrichtung (RK) ausgeschaltet ist, meßbar. Dieser Spannungsabfall (U1) wird durch den Analog-Digital-Umsetzer (ADC) gemessen und in umgewandelter Form dem Mikrorechner (MC) weitergegeben.If the semiconductor switch (HL) is now switched on at time (T1), the current flow from the positive pole of the battery via the glow plug (VS), the switching path of the semiconductor switch (HL) and the glow plug (V) to the negative pole of the current source (B) is made possible . If the glow plug (V) is in perfect electrical condition, then a small amount (U1) of the total voltage applied drops across the switching path of the semiconductor switch (HL). This voltage drop (U1) can be measured over the entire period (T), which extends from T1 to T2 and in which the semiconductor switch (HL) is switched on and the second switching device (RK) is switched off. This voltage drop (U1) is measured by the analog-to-digital converter (ADC) and passed on in a converted form to the microcomputer (MC).
Wird nun zum Zeitpunkt (T2) nach Ablauf der Zeitdauer (T) zusätzlich die zweite Schalteinrichtung (RK) eingeschaltet, so ist wegen des geringen Übergangswiderstands zwischen den Relaiskontakten (RK) nur noch ein verschwindend geringer Spannungsabfall (UDS) an der Schaltstrecke des Halbleiterschalters (HL) meßbar.If the second switching device (RK) is also switched on at time (T2) after the time (T) has elapsed, there is only a negligible voltage drop (UDS) on the switching path of the semiconductor switch due to the low contact resistance between the relay contacts (RK) ( HL) measurable.
Zum Zeitpunkt (T3) wird die zweite Schalteinrichtung (RK) geöffnet, so daß der Stromfluß wieder über die Schaltstrecke des Halbleiter-Bauelements (HL) erfolgt. Entsprechend fällt ein Spannungsbetrag (U1) an der Schaltstrecke des Halbleiter-Bauelements (HL) ab. Nach Ablauf der Zeitdauer (T), also zum Zeitpunkt T4 in der Figur 2, wird auch das Halbleiter-Bauelement (HL) ausgeschaltet. Der Stromfluß wird unterbrochen. An der Schaltstrecke des Halbleiterschalters (HL) liegt nun wieder die gesamte Batteriespannung (UB) an.At time (T3), the second switching device (RK) is opened so that the current flows again over the switching path of the semiconductor component (HL). Accordingly, a voltage amount (U1) drops across the switching path of the semiconductor component (HL). After the time period (T) has elapsed, that is to say at time T4 in FIG. 2, the semiconductor component (HL) is also switched off. The current flow is interrupted. The entire battery voltage (UB) is now again applied to the switching path of the semiconductor switch (HL).
Befindet sich die Glühkerze (V) nicht in einwandfreiem Zustand, so kann dies während der Zeitdauer (T) durch die Überwachungseinrichtung erfaßt werden. Weist die Glühkerze (V) einen Kurzschluß auf, so würde während der Zeitdauer (T) die gesamte Spannung (UB) an der Schaltstrecke des Halbleiter-Bauelements (HL) abfallen. Das heißt, der gemessene Spannungsabfall (UDS) würde über dem in der Figur 2 dargestellten ersten Schwellwert (US1) liegen. Dieser erhöhte Spannungsabfall würde durch die Überwachungseinrichtung erkannt und ein erstes Fehlersignal an die erste Anzeigeeinrichtung (FL1) geliefert. Zugleich wird dann der Halbleiterschalter (HL) ausgeschaltet, um eine Überlastung des Halbleiter-Bauelemente (HL) zu verhindern.If the glow plug (V) is not in perfect condition, this can be detected by the monitoring device during the period (T). If the glow plug (V) had a short circuit, the entire voltage (UB) at the switching path of the semiconductor component (HL) would drop during the period (T). This means that the measured voltage drop (UDS) would be above the first threshold value (US1) shown in FIG. 2. This increased voltage drop would be recognized by the monitoring device and a first error signal would be delivered to the first display device (FL1). At the same time, the semiconductor switch (HL) is then switched off in order to prevent the semiconductor components (HL) from being overloaded.
Liegt im Glühkerzenstromkreis oder an der Glühkerze (V) eine Leitungsunterbrechung vor, so würde an der Schaltstrecke des Halbleiter-Bauelements (HL) in der Zeitdauer (T) nur ein verschwindend geringer Spannungsbetrag abfallen. Das heißt, der gemessene Spannungsabfall liegt dann unterhalb der in der Figur 2 dargestellten zweiten Spannungsschwelle (US2). Dieser Sachverhalt wird ebenfalls von der Überwachungseinrichtung ermittelt und führt dazu, daß die Überwachungseinrichtung ein zweites Fehlersignal an die zweite Anzeigeeinrichtung (FL2) liefert.If there is a line interruption in the glow plug circuit or on the glow plug (V), only a negligibly small amount of voltage would drop across the switching path of the semiconductor component (HL) in the time period (T). This means that the measured voltage drop is then below the second voltage threshold (US2) shown in FIG. 2. This fact will likewise determined by the monitoring device and leads to the monitoring device supplying a second error signal to the second display device (FL2).
Es zeigt sich, daß durch die erfindungsgemäße Vorglüheinrichtung nicht nur einfach und kostengünstig die Relaiskontakte (RK) geschont werden können, sondern auch auf einfache Art und Weise eine Überwachung des Glühkerzenstromkreises auf Kurzschlüsse und Leitungsunterbrechungen möglich ist.It turns out that the preheating device according to the invention not only protects the relay contacts (RK) easily and inexpensively, but also enables the glow plug circuit to be monitored for short circuits and line interruptions in a simple manner.
Es ist weiterhin insbesondere aufgrund der kurzen Schaltzeit des Halbleiter-Bauelements (HL) möglich, die Zeitdauer (T) gegenüber dem Vorbekannten auf einen Wert von etwa 1 ms zu verkürzen. Dadurch wird sichergestellt, daß die Zeitdauer bis zum vollständigen Aufheizen der Glühkerzen (V) gegenüber dem Vorbekannten wesentlich verkürzt ist. Dies bedeutet einen großen Komfortgewinn für die Bedienung der selbstzündenden Brennkraftmaschine.It is also possible, in particular because of the short switching time of the semiconductor component (HL), to shorten the time period (T) to a value of approximately 1 ms compared to the prior art. This ensures that the time it takes for the glow plugs (V) to heat up completely to be shortened compared to the prior art. This means a great gain in comfort for the operation of the self-igniting internal combustion engine.
Schließlich kann durch die erfindungsgemäße Vorglüheinrichtung vorteilhaft die Glühkerze (V) periodisch ein- und ausgeschaltet werden. Dies hat den Vorteil, daß Versorgungsspannungsschwankungen und die Glühkerzentemperatur durch Veränderung der Einschaltzeiten verändert werden können. Es ist insbesondere vorteilhaft, diese periodische Ein- und Ausschaltung mit konstanter Einschaltzeit und abhängig von der Versorgungsspannung und der Glühkerzentemperatur veränderlicher Ausschaltzeit durchzuführen, weil durch die Verwendung des Mikrorechners (MC) das dazu erforderliche Taktsignal auf einfache Art und Weise bereitgestellt werden kann. Das heißt, der in der Figur 2 dargestellte Ein- und Ausschaltvorgang würde sich periodisch wiederholen.Finally, the glow plug (V) can advantageously be switched on and off periodically by the pre-glow device according to the invention. This has the advantage that supply voltage fluctuations and the glow plug temperature can be changed by changing the switch-on times. It is particularly advantageous to carry out this periodic switch-on and switch-off with a constant switch-on time and a switch-off time that varies depending on the supply voltage and the glow plug temperature because the clock signal required for this can be provided in a simple manner by using the microcomputer (MC). This means that the switch-on and switch-off process shown in FIG. 2 would be repeated periodically.
Aufgrund der großen Zahl von Schaltvorgängen, die bei einer periodischen Aufheizung der Glühkerze (V) erforderlich sind, machen sich die Vorteile der erfindungsgemäßen Vorglüheinrichtung dann besonders stark bemerkbar, weil durch die erfindungsgemäße Vorglüheinrichtung ein Abbrand der Relaiskontakte (RK) kaum mehr merklich ist.Because of the large number of switching operations that are required for periodic heating of the glow plug (V), the advantages of the preheating device according to the invention are particularly noticeable because the preheating device according to the invention means that the relay contacts (RK) are hardly noticeable.
Statt einer Glühkerze (V) können auch andere elektrische Verbraucher durch die erfindungsgemäße Einrichtung ein- und ausgeschaltet werden.Instead of a glow plug (V), other electrical consumers can also be switched on and off by the device according to the invention.
Claims (9)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19873701838 DE3701838A1 (en) | 1987-01-23 | 1987-01-23 | DEVICE FOR PROTECTING RELAY CONTACTS |
DE3701838 | 1987-01-23 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0279042A1 EP0279042A1 (en) | 1988-08-24 |
EP0279042B1 true EP0279042B1 (en) | 1991-08-07 |
EP0279042B2 EP0279042B2 (en) | 1994-05-25 |
Family
ID=6319328
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19870117879 Expired - Lifetime EP0279042B2 (en) | 1987-01-23 | 1987-12-03 | Arrangement for protecting relay contacts |
Country Status (3)
Country | Link |
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EP (1) | EP0279042B2 (en) |
DE (1) | DE3701838A1 (en) |
ES (1) | ES2024482T5 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4012470A1 (en) * | 1990-04-19 | 1991-10-24 | Hella Kg Hueck & Co | Relay contact protector in car network - is for relay with break and make contacts, conductively coupled to consumer appliance |
DE4244119C1 (en) * | 1992-12-24 | 1994-03-24 | Hella Kg Hueck & Co | Protecting relay contacts against overloading - using controlled switch with switching path in parallel with contacts and monitoring elements for load current circuit |
DE4244116C1 (en) * | 1992-12-24 | 1994-03-24 | Hella Kg Hueck & Co | Protecting relay contacts against overloading - using controllable switch with path in parallel with contacts and electronic control |
DE102005002490A1 (en) * | 2005-01-19 | 2006-07-27 | Hella Kgaa Hueck & Co. | Motor vehicle electrical system switching device, has charging and discharging unit to charge and discharge electrical components of vehicle electrical system and switched before closing or after opening of isolating switch |
Family Cites Families (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3558910A (en) * | 1968-07-19 | 1971-01-26 | Motorola Inc | Relay circuits employing a triac to prevent arcing |
CA1132661A (en) * | 1979-02-14 | 1982-09-28 | Rodney Hayden | Resistive device sensor |
DE2907772A1 (en) * | 1979-02-28 | 1980-09-11 | Vdo Schindling | METHOD AND CIRCUIT FOR PREHEATING A DIESEL ENGINE |
DE2935196A1 (en) * | 1979-08-31 | 1981-03-19 | Robert Bosch Gmbh, 7000 Stuttgart | SAFETY DEVICE FOR ELECTRICAL CONSUMERS IN MOTOR VEHICLES |
US4420784A (en) * | 1981-12-04 | 1983-12-13 | Eaton Corporation | Hybrid D.C. power controller |
JPS58189375U (en) * | 1982-06-14 | 1983-12-16 | 日産自動車株式会社 | Internal combustion engine glow plug control device |
DE3224587A1 (en) * | 1982-07-01 | 1984-01-05 | Bayerische Motoren Werke AG, 8000 München | SWITCHING ARRANGEMENT FOR GLOW PLUGS OF A DIESEL INTERNAL COMBUSTION ENGINE |
YU115584A (en) * | 1984-07-02 | 1987-06-30 | Iskra Sozd Elektro Indus | Circuit for automatic controlled glowing device |
DE3433367A1 (en) * | 1984-09-12 | 1986-03-20 | Robert Bosch Gmbh, 7000 Stuttgart | DEVICE FOR CONTROLLING THE ENERGY SUPPLY TO A HOT PLACE |
US4636907A (en) * | 1985-07-11 | 1987-01-13 | General Electric Company | Arcless circuit interrupter |
DE3608602A1 (en) * | 1986-03-14 | 1987-09-17 | Siemens Ag | Method for the activation of glow plugs in diesel engines |
-
1987
- 1987-01-23 DE DE19873701838 patent/DE3701838A1/en active Granted
- 1987-12-03 EP EP19870117879 patent/EP0279042B2/en not_active Expired - Lifetime
- 1987-12-03 ES ES87117879T patent/ES2024482T5/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
ES2024482T5 (en) | 1995-08-16 |
EP0279042A1 (en) | 1988-08-24 |
ES2024482B3 (en) | 1992-03-01 |
EP0279042B2 (en) | 1994-05-25 |
DE3701838C2 (en) | 1991-08-14 |
DE3701838A1 (en) | 1988-08-04 |
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