Electricity: magnetically operated switches – magnets – and electr – Permanent magnet-actuated switches – Plural magnets
Reexamination Certificate
1999-06-30
2001-01-16
Donovan, Lincoln (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Permanent magnet-actuated switches
Plural magnets
C335S205000
Reexamination Certificate
active
06175290
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to steering column stalk mounted control switches and, more particularly, to contactless steering column mounted control switches for heavy duty vehicles.
BACKGROUND OF THE INVENTION
The operator's compartment of most vehicles, such as Class 8 trucks, generally include control switches that are in communication with a variety of electrical systems. In a current typical system, actuation of the switch produces a relatively high current which is capable of breaking through the resistance of corrosion, oxidation, and contaminants that may have formed on the contacts. However, modern electronic applications, such as computers, do not require high current. Computers generally employ very low current output to activate the switching action of a larger driver circuit. Such driver circuits are used to actuate a variety of systems, such as turn signals or cruise control of the vehicle. Low current switches are much more susceptible to environmental contamination.
Switches currently available for such systems are typically exposed contact switches. Contact switches generally include a lever and attached, plated or unplated, copper contacts that may be directly actuated into and out of physical contact with corresponding contacts of the driver circuit. In a typical arrangement, the lever extends from within a housing disposed within the steering column control stalk of the vehicle. Displacement of the lever causes the lever contact to be displaced into contact with the driver circuit contact located within the housing. Contact between the lever contact and the driver circuit contact results in a closed circuit, thereby actuating the turn signal or some other feature of the vehicle. Although such switches are effective at changing the state of a switch, they are not without their problems.
First, because physical contact between the lever contact and circuit contact is required to close the circuit, and the contacts are exposed to the environment, such switches often suffer high rates of failure. Additionally, reliability is also compromised due to frictional contact and wear on pivoting and detenting features. Debris or corrosion may build up at the contact points between the lever contact and the circuit contact, thereby causing an unintended and undesirable increase in impedance of the switch. Such corrosion also decreases the useful life of the switch. Finally, such switches are relatively expensive to manufacture due to the complexity of the contact arrangements and the need to switch relatively high current.
Thus, there exists a need for a contactless switch that is economical to manufacture, has a high degree of reliability and meets the performance expectations of the end user.
SUMMARY OF THE INVENTION
In accordance with the present invention, a contactless control switch for a vehicle is provided. The contactless switch includes a housing and a pivot assembly disposed within the housing. The contactless switch also includes a switch actuator having first and second ends. The switch actuator is coupled to the pivot assembly for pivoting motion of the switch actuator in response to a force applied to the switch actuator. A contactless switch formed in accordance with the present invention also includes first and second proximity sensors and a first magnet. The proximity sensors are disposed within the housing and the first magnet is fastened to the switch actuator second end. The first magnet may be selectively displaced into and out of close proximity with one of the proximity sensors when the force is applied to the switch actuator.
In accordance with further aspects of this invention, the pivot assembly includes first and second portions. The first portion is supported by the housing for transfer of loads from the switch actuator to the housing, and the second portion is fastened to the switch actuator. The second portion includes a first pivot point about which the switch actuator and second portion pivot to selectively displace the first magnet into close proximity with a predetermined number of the proximity sensors.
In accordance with other aspects of this invention, the second portion further includes a second pivot point about which the switch actuator and second portion pivot to selectively displace the first magnet into close proximity with a predetermined number of the proximity sensors.
In accordance with still other aspects of this invention, the switch actuator pivots about the first and second pivot points along a stroke path, such that the first magnet is selectively reciprocated between the plurality of proximity sensors along a predetermined path.
In accordance with still yet other aspects of this invention, the plurality of proximity sensors are disposed within the housing, and the proximity sensors are reed switches, such that the plurality of proximity sensors are positioned at predetermined angles relative to the path to assure activation of the selected reed switch due to motion of the switch actuator, and assure de-activation of the selected reed switch when the switch actuator is released, thereby minimizing the stroke of the switch actuator. In one embodiment of the present invention, the predetermined angles are oblique angles.
A contactless control switch for a vehicle formed in accordance with the present invention has several advantages over currently available control switches. A switch formed in accordance with the present invention has a longer useful life than contact switches currently available because there is no physical contact between switch actuator components and electrical circuit components. Additionally, because the proximity sensors are positioned within the switch at predetermined angles relative to the path of the switch actuator, such an arrangement minimizes the stroke of the switch actuator, thereby reducing the size of the switch. Further, because the first portion of the pivot assembly is supported by both the switch housing and mounting bracket, loads from the switch actuator are distributed directly to the mounting bracket. Finally, because the second portion of the pivot assembly is disposed within the housing such that it is positioned between the first portion of the switch assembly and the plurality of proximity sensors, such a switch results in a motion anticipated by the end user. Thus, a contactless control switch for a vehicle formed in accordance with the present invention is economical to produce, has a high switching action reliability and produces the customary and anticipated response while changing state of the switch.
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Forsythe Alan K.
Morris John M.
Simmons Charles H.
Thompson Andrew F.
Christensen O'Connor Johnson & Kindness PLLC
Donovan Lincoln
GT Development Corporation
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