Electromagnetic fuel injector linear motor and pump

Abstract

The invention is a linear electromagnetic motor which operates to reciprocate a pump plunger within a central pump barrel. The motor has a ferromagnetic armature annularly connected to the pump plunger, located in an annular space in the motor core about the pump plunger. The armature is itself annularly surrounded by a permanent polarizing ring magnet located between two motor drive coils. The motor operates by switching the polarizing magnetic flux of the ring magnet by a control magnetic flux created by electric current in the motor drive coils. On its backward end, the pump plunger is biased by a spring in the direction of its forward stroke. However, when the armature is latched by the magnet at its backward stroke location (distance A=0), the strength of the magnet overcomes the bias in this spring. As soon as the control magnetic flux changes, the magnetic latch at the backward stroke location is released, and the spring bias plus the magnetic attraction in the forward stroke direction act to quickly accelerate the armature and the pump plunger in the forward stroke direction at high speed and force. Before the end of its forward stroke, the pump plunger contacts a check slug whose location is mechanically adjusted to create a desired volume of fuel to be delivered. The contact of the check slug with the plunger suddenly seals off a volume of fuel existing within the voids of a spray valve. The pump plunger can be said to have crashed into the fuel, whose pressure builds rapidly as a result. When the fuel pressure reaches the set pressure of a relief valve it escapes as a spray into an engine headspace until the plunger reaches its mechanical end-stop.