Electromagnetic latching switch

#The present invention concerns switches and, more particularly, the present invention concerns a magnetic latching switch.

#Electrical switches have many applications. For example, switches have been used in interlock circuits for lawn and garden tractors and similar vehicles, automobile car doors, refrigerator doors, and home appliances. One type of switch is a momentary switch that includes an actuator that is automatically returned to a normal position. The actuator may be returned to the normal position by a biasing member, such as a spring or a dome contact. In the normal position, two terminals of the switch are in a first state (either open or closed). The actuator can be moved to an actuated position by imparting a force on the actuator. For example, the actuator of a pushbutton switch with a normally extended actuator can be depressed by a user's finger or it can be positioned such that closing a door or sitting on a seat moves the actuator from the normal, extended position to an actuated, depressed position. When the actuator is in the second position, the terminals of the switch are in a second state (closed if the terminals were open in the fist state or open if the terminals were closed in the first state). When the force is removed from the actuator, the actuator automatically returns to the normal position.

#Another type of switch is a sustained action switch. A two position sustained action switch includes an actuator that is moveable between two positions. The first position corresponds to a first state of the switch terminals and the second position corresponds to a second state of the switch terminals. The actuator can be moved from the first position to the second position by imparting a force on the actuator. The actuator remains in the second position until a second force is applied to the switch actuator to return the actuator to the first position.

#FIG. 1 is a view of an electromagnetic latching switch with an actuator biased to a normal position;

#FIG. 2 is a view taken along the plane indicated by lines 2—2 in FIG. 1;

#FIG. 3 is a view similar to the view of FIG. 1 with an actuator in an actuated position;

#The present disclosure is directed to a magnetic latching switch 10. The magnetic latching switch 10 includes a pair of switch terminals 12, a switch actuator 14, an electromagnet 16, a biasing member 18, and a switch contact 20. The switch actuator 14 is manually moveable from a first position (FIGS. 1 and 2) where the switch terminals 12 are in a first state to a second position (FIGS. 3 and 4) where the switch terminals are in a second state. In the embodiments illustrated by FIGS. 1–8, the terminals 12 are electrically isolated (FIG. 2) in the first state and are bridged (FIG. 4) by the contact 20 in the second state. It should be readily apparent that the magnetic latching switch could be configured such that the terminals 12 are bridged by the contact 20 in the first state and are isolated in the second state. The electromagnet 16 selectively applies a magnetic field. Applying the magnetic field with the electromagnet when the switch actuator is in the second position maintains the switch actuator in the second position. The biasing member 18, illustrated as a spring in the Figures, is coupled to the switch actuator such that the biasing member automatically returns the switch actuator 14 from the second position to the first position when the magnetic field is removed.

#The magnetic latching switches 10 illustrated by FIGS. 1–6 and 9–13 selectively operate in a momentary switch mode or a sustained action switch mode. The magnetic latching switches operate as a momentary switch when the electromagnet of the switch is not energized and operates as a sustained action switch when the electromagnet is energized. Energization and de-energization of the electromagnet is independent of the position of the switch actuator. In the embodiments illustrated by FIGS. 1–8, the electromagnet is selectively energized by closing an external switch 22 that couples terminals 24 of the electromagnet 16 to a source 26 of electrical energy, such as a battery.

#FIGS. 1–4 illustrate operation of an electromagnetic switch 10 when the switch 22 is open and the electromagnet is thus not energized. The switch actuator 14 is selectively moveable by a user from a first position to a second position. In the embodiment illustrated by FIGS. 1–4, the contact 20 electrically bridges the first and second switch terminals 12 when the switch actuator is in the second position. The switch terminals are electrically isolated when the switch actuator is in the first position. The biasing member 18 is coupled to the switch actuator 14, such that the switch actuator is biased to the first position. The biasing member 18 automatically returns the switch actuator 14 from the second position to the first position when the user is not applying force to the switch actuator and the switch 22 is open.