Electromagnetically energized actuator

#The present invention relates to electromagnetically energized actuators, and more particularly to an electromagnetically energized actuator configured for minimization of plunger friction and plunger impact.

#A conventional pneumatic valve 10 is depicted at FIGS. 1 through 2 in which an electromagnetically energized actuator used to control flow of fuel vapors from a canister to the engine intake manifold. The conventional pneumatic valve 10 includes a housing 12, an electromagnet assembly 14 which includes a solenoid 14a wound on a spool 14b, a brass tube 16 concentrically disposed relative to the spool, a stop 18 fixedly disposed in the tube and composed of a highly permeable material, a plunger 20 reciprocally disposed within the tube and composed of a highly permeable material, a spring 22 of a spring assembly 24 formed at the facing ends 18f, 20f of the stop and the plunger which biases the plunger away from the stop, and a valve seat 26 located on the plunger at an end thereof distal from the aforementioned facing end. The combination of the plunger, the stop, the spring assembly a first plate 32 and a second plate 34, as shown at FIG. 2, constitutes a conventional electromagnetically energized actuator 38.

#When the solenoid is energized, the plunger is magnetically pulled toward the stop, overcoming the biasing by the spring such that the facing end of the plunger moves toward the facing end of the stop, with the consequence that the valve seat is opened. When the solenoid is de-energized, the spring pushes the plunger away from the stop, thereby again closing the valve seat.

#FIG. 1 is a sectional side view of a prior art pneumatic valve.

#FIG. 1A is a schematic diagram of an electrical control circuit for the prior art pneumatic valve of FIG. 1.

#FIG. 2 is a sectional side view of the prior art electromagnetically energized actuator of the pneumatic valve of FIG. 1.

#Referring now to the Drawing, FIGS. 3 through 6 depict an example of an electromagnetically energized actuator 100 according to the present invention. The electromagnetically energized actuator 100 may, for example, be used in a pneumatic valve as depicted at FIGS. 1 and 1A in substitution for the conventional electromagnetically energized actuator thereof (as also shown at FIG. 2), or may be used in other device applications.

#The electromagnetically energized actuator 100 includes a plunger 102, a stop 104, a first plate 106 having a first plate opening 106a, a second plate 108 having a second plate opening 108a, and a polymer tube 110 extending between the first and second plate openings and into which is reciprocally situated the plunger and stationarily situated the stop. The plunger 102, the stop 104, the first plate 106 and the second plate 108 are each composed of highly permeable material (ie., ferromagnetic material). The plunger 102 and the stop 104 are preferably of cylindrical cross-section. A spring 112 of a spring assembly 114 formed at the facing ends 102f, 104f respectively of the stop and the plunger biases the plunger 102 away from the stop 104.

#The first and second plates 106, 108 form part of an electromagnetic circuit which includes a selectively energizable solenoid, as for example the solenoid 14a shown at FIG. 1. With the magnetic circuit so provided, the magnetic flux B from the solenoid (see 14a in FIG. 1) passes through the first plate 106, crosses a compound secondary air gap GS′ between the first plate and the plunger 102, through the plunger, across a primary air gap GP′ to the stop 104, through the stop, and into the second plate 108.