Appeal No. 1998-1503
Application No. 08/676,907
The invention is directed to a circuit for driving an
excitation coil of an electromagnetically driven reciprocating
pump for use in a fuel injection device.
Independent claim 2 is reproduced as follows:
2. A reciprocating pump used as a fuel injection
device, comprising:
an excitation coil which is driven by an excitation
current;
an armature operatively associated with the excitation
coil for operating a fluid-displacement element of the pump;
and
an excitation circuit operative for supplying current
pulses to the excitation coil, the excitation circuit
comprising:
a power transistor in series with the excitation coil and
with a measuring resistor having a side connected to the
transistor;
a comparator having an output and two inputs, the output
being connected to a control input of the transistor;
one input of the comparator being responsive to a
selectively variable reference signal corresponding to a
predetermined target current in the excitation coil; and
the other input of the comparator being connected to the
side of the measuring resistor that is connected to the
transistor and thus being responsive to the actual current
through the excitation coil, so that the comparator compares
the actual current and the target current and operates to
drive the transistor to adjust the actual current to the
-2-
Page: Previous 1 2 3 4 5 6 7 8 9 10 Next
Last modified: November 3, 2007