Apparatus and method for driving and controlling electric consumers, in particular heat plugs

An apparatus for driving and testing at least two glow plugs of a diesel engine, the apparatus comprising:

• a voltage supply;
• a plurality of semiconductor switches for switching on and off corresponding ones of the glow plugs;
• measuring resistor means connected in series with said voltage supply and said glow plugs;
• a microprocessor for driving said semiconductor switches in a time displaced manner one after the other;
• detection means for detecting a voltage across said measuring resistor means to detect currents flowing through said glow plugs wherein the currents are utilized for detecting the presence of an open circuit or a short circuit;
• and,
• said microprocessor including means electrically connected to said switches for driving said switches in a time displaced manner so as to cause the sum of the currents flowing through all of said glow plugs to provide a quasi-steadystate current rise as said switches are driven into their conductive state.

An apparatus for driving and testing at least two glow plugs of a diesel engine, the apparatus comprising:

• a voltage supply;
• a plurality of semiconductor switches for switching on and off corresponding ones of the glow plugs;
• measuring resistor means connected in series with said voltage supply and said glow plugs;
• a microprocessor for driving said semiconductor switches in a time displaced manner one after the other;
• detection means for detecting a voltage across said measuring resistor means to detect currents flowing through said glow plugs wherein the currents are utilized for detecting the presence of an open circuit or a short circuit;
• and,
• said microprocessor including means for determining an instantaneous electrical energy of an individual glow plug from said detected currents and for individually shortening or lengthening the switched-on duration of each of the glow plugs for adjusting a predetermined power of the glow plugs.

An apparatus for driving and testing at least two glow plugs of a diesel engine, the apparatus comprising:

• a voltage supply;
• a plurality of semiconductor switches for switching on and off corresponding ones of the glow plugs;
• measuring resistor means connected in series with said voltage supply and said glow plugs;
• a microprocessor for driving said semiconductor switches in a time displaced manner one after the other;
• detection means for detecting a voltage across said measuring resistor means to detect currents flowing through said glow plugs wherein the currents are utilized for detecting the presence of an open circuit or a short circuit;
• said microprocessor including an electronic, multistage switching circuit for driving said semiconductor switches;
• and,
• said multistage switching circuit being a shift register.