摘要:
A circuit for neutralizing very fast current fluctuations in a power consumer circuit, such as an integrated circuit having a pair of input or output conductors includes a bipolar transistor 17 whose collector is connected via a parallel connection of a semiconductor diode and a resistor to one of the conductors. The emitter of the transistor is grounded and the base is connected to the other conductor. Another parallel connection of a diode and a resistor is connected between the two conductors to bias the transistor to a preset current when a standard current of a constant magnitude flows through the consumer circuit. If current surges or breaks occur in the standard current, the preset current flowing through the collector resistor undergoes corresponding changes and a compensating current is very fast loaded to the conductors through the capacitance of the barrier layer of the p-n junction of the collector diode to neutralize the changes of the standard current.
摘要:
The voltage developed by a primary winding of an ignition coil is supplied to a voltage divider for furnishing an analog signal of reduced amplitude for evaluation on an analog basis, which reduced amplitude analog signal is averaged by a capacitor connected between the voltage divider tap and ground. The capacitor eliminates the undesired effect of voltage spikes, but is not large enough to interfere with the measurement of voltages exceeding the ignition-initiating primary winding voltage value. The same reduced primary winding voltage is supplied through an input resistor to one input of a differential amplifier connected to operate as a switch having hysteresis and having a reference voltage applied to it such that the output will be the provision of a steady voltage having a duration corresponding to the spark discharge duration, for subsequent digital evaluation. The tap of the voltage divider that provides the analog output voltage for the system is subjected to a clamping action provided by another voltage divider of low ohm value connected across a 5-volt source and having its tap connected to the tap of the first mentioned voltage divider by a diode, so that primary winding voltages above the spark-initiating voltage will be measured on a reduced scale, while the differential amplifier and other integrated circuits are prevented from having overvoltages applied to them. The circuit is therefore suited for economical manufacture in so-called hybrid technology.
摘要:
In a known ignition system, the emitter-collector circuit of the ignition transistor is connected in series with the primary winding of the ignition coil and with a precision resistor. When the voltage across the latter exceeds a predetermined value, an auxiliary transistor is switched to a conductive state. The emitter-collector circuit of the auxiliary transistor is connected to the base of the ignition transistor and, when conductive, prevents further increases of current through the primary winding of the ignition coil. To protect this circuit, a series circuit including two Zener diodes is connected between the base and collector of the ignition transistor. Further, a voltage divider is connected in parallel with the emitter-collector circuit of the ignition transistor and an additional resistor is connected between the base and the emitter thereof. When overvoltages across the primary winding cause breakdown of the Zener diodes, the current through the Zener diodes is blocked from the emitter-collector circuit of the auxiliary transistor either by a diode or by a blocking transistor having an emitter-collector circuit connected in parallel with the base-emitter circuit of the auxiliary transistor. The blocking transistor is maintained in the conductive state blocking the auxiliary transistor throughout the application time of an externally applied blocking signal which is adapted to maintain the ignition transistor in the blocked state.
摘要:
A switch connected in series with the ignition coil is "on" and "off," respectively, in the presence and absence of a pulse furnished by a pulse generator operating in synchronism with the crankshaft of the engine. If the pulse width of the pulses is too small for the current in the ignition coil to reach the minimum value required for ignition, the closing time of the series switch is advanced, while if the pulse width is too long, causing excess heat dissipation in the coil, the closing time of the switch is retarded. To accomplish this, a first digital counter counts downwards for a predetermined time and upwards for a time period in which the current in the ignition coil exceeds a predetermined current. Upon interruption of the current in the coil, the then-present value in the first digital counter is transferred to a second digital counter. The second counter then counts down at a predetermined rate until a predetermined count is reached. At this time, the series switch is switched to the conductive state.
摘要:
A switching transistor (7, 9) is serially connected with the primary (5) of an ignition coil; current flow therethrough is controlled from an a-c signal generator (16) with respect to an ON threshold level (Ue) to store electromagnetic energy, and an OFF threshold level (Ua) to generate a spark; a variable conductivity circuit (26) controlled from a sensing resistor (8) modifies the response level of the threshold switch (13) with respect to the null or cross-over level of the applied signal. To prevent excessive current flow under idle-speed conditions, in accordance with the invention, the ON threshold level, at least, of the switch is shifted by introducing an auxiliary bias voltage derived from an auxiliary capacitor (36) and connected (37, 38) by the signal source through a diode (38) which prevents application of an auxiliary bias voltage to the threshold switch (13) under extremely low, e.g. starting conditions, permits application of the additional bias voltage providing for shift of the ON response level (Ue) under idling conditions, but again loses control as the speed continues to increase, and control by the variable conductivity circuit takes over.
摘要:
A transistor switch connected in series with the primary winding of the ignition coil permits and blocks current flow through the coil when in a conductive and non-conductive state respectively. Normally, the switch is "on" and "off" respectively in the presence and absence of an ignition current pulse furnished in synchronism with the rotation of the crankshaft of the engine. For increasing speeds, the time the switch is "on" prior to the ignition time is increased by switching it to the conductive state when the charge on a control capacitor reaches a predetermined charge. The charge on the control capacitor is changed in a first direction following receipt of each ignition signal. The rate of change of charge depends upon the resistance of the emitter-collector circuit of a first control transistor. The latter is, in turn, determined by the charge on an integrator capacitor which varies with changes in engine speed. When the charge on the control capacitor reaches a predetermined charge, the output transistor switch to the conductive state allowing current flow in the ignition coil.
摘要:
Oscillations which would normally occur when the current in the primary winding of an ignition coil is limited to a predetermined value prior to ignition are suppressed by use of a feedback resistor. Specifically, the basic circuit consists of the primary winding of the ignition coil connected in series with a Darlington transistor configuration which, in turn, is connected in series with a measuring resistor, at a common point. The input of the current control system is connected to the common point through an additional resistor, while the output of the control circuit is connected to the input base of the Darlington configuration. Oscillations which might otherwise occur are suppressed by the use of a feedback resistor connected between the input and output lines of the control circuit.
摘要:
The voltage across a capacitor is changed in a first direction while the current in the primary winding of the ignition coil increases to a predetermined value less than the value required for ignition and is thereafter changed in a second direction until ignition takes place. The voltage across the capacitor is applied to the inverting input of a difference amplifier constituting a threshold stage controlling the initiation and termination of current flow through the ignition coil. The two changes are symmetrical when the engine speed remains constant. The residual voltage across the capacitor at the end of the second change is maintained until the start of the next subsequent first change, so that the time at which the threshold stage switches in, that is the time at which primary current starts to flow in the ignition coil changes as a function of the residual voltage in the capacitor.
摘要:
When the current through the primary winding of an ignition coil of an ignition system in an internal combustion engine has increased to a predetermined value, base current for a power transistor connected in series with the coil is shunted away, causing a rise in voltage across the primary winding. When the voltage rise across the primary winding has reached a maximum allowable value less than the value required to cause the generation of a spark, the transistor is switched back to the fully conductive state. This cycle is repeated during the time the transistor would normally be conductive and terminates at the ignition time, that is at the time the transistor is blocked by the ignition timing circuit of the internal combustion engine to create the spark.
摘要:
An internal combustion engine is comprised of at least one engine cylinder, devices for introducing a combustion mixture into the cylinder, and an electrical igniting element operative for igniting the combustion mixture in the cylinder once per ignition cycle. An ignition transformer has a secondary winding connected across the igniting element, and also has a primary winding. A flow of current is established through the primary winding. An electronic switch is connected in the current path of the primary winding to control the flow of current through the primary winding. A triggering unit generates a train of crankshaft-synchronized triggering signals. A monostable control circuit has a trigger input for receipt of such triggering signals, and is operative when triggered into the unstable state for rendering and maintaining the electronic switch nonconductive for the duration of the unstable state, so as to interrupt the flow of current through the primary winding and induce across the secondary winding a voltage surge causing the igniting element to ignite the combustion mixture in the engine cylinder. When the monostable control circuit reverts to its stable state, it renders and maintains the electronic switch conductive for the duration of the stable state, whereby to establish a build-up of current flow in the primary winding in preparation for the next interruption of current flow. The monostable control circuit includes a timing stage operative for automatically .[.increasing.]. .Iadd.decreasing .Iaddend.the ratio of the duration of the unstable state to the duration of the ignition cycle with increasing engine speed within a predetermined range of engine speeds.