Electricity: electrical systems and devices – Control circuits for electromagnetic devices – For relays or solenoids
Reexamination Certificate
1999-10-06
2003-04-08
Jackson, Stephen W. (Department: 2836)
Electricity: electrical systems and devices
Control circuits for electromagnetic devices
For relays or solenoids
C361S152000
Reexamination Certificate
active
06545852
ABSTRACT:
BACKGROUND
1. Field of the Invention
The present invention relates generally to operation of bi-stable and mono-stable magnetic latching mechanisms, and more particularly to a device, method, and system for bi-stable and mono-stable magnetic latching mechanisms in safety related applications such as automotive brake systems and control mechanisms for the power industry, nuclear and conventional, that utilize permanent magnetic latching devices in control and safety systems.
2. Background of the Invention
The new generation of pulse operated magnetic latching devices require a bi-polar pulse in order for the magnetic latching device to operate as intended or designed. This divergence from traditional driving method of constant powered devices has caused or created problems in finding method(s) of effectively operating this generation of magnetic devices, especially units requiring substantial power operating in operationally critical environments. These pulse operated short duty cycle devices generate more ‘switching/change-over force’ than their constant powered counter-parts, but lack the user confidence of the constant powered devices.
Manufacturers and users of these new magnetic latching devices have learned that just providing a pulse to the unit with no position indicator or operations indicator is not sufficient to meet today's safety requirements and provide the operators or other users with the assurance of correct operation. The continuously powered devices, which are being replaced by the new generation of magnetic latching devices, have an inherent built-in safety mechanism and operational confidence lacking in the new magnetic latching designs.
Several manufacturers have attempted to address these problems by adding switches, modifying the magnetic circuitry to cause closure of a magnetic switch at one position, or developing electronics to monitor position by determining induction value of the magnetic assembly or visual indicators.
Another approach used by manufacturers and users is to over drive the magnetic latching mechanism by providing a higher voltage pulse of longer duration than required in order to establish an operating confidence level with the magnetic latching device. This causes heating of the brake or clutch, damage to the winding installation, and excessive power consumption, all of which the design was supposed to overcome.
The automotive environment does not make wide use of bi-polar power drivers that are required to operate these medium to high power driver requirements. (There appear to be no, or at least very few, high power, 30A, Double Pole Double Throw relays for automotive applications.) The industrial environment provides a better source for high power double pole double throw relays than the automotive industry, but lacks an economical method of providing the bi-polar electrical pulse necessary to correctly drive or operate the new generation of magnetic latching devices and mechanisms.
Various sources provide background information relating to different aspects or components of the invention. For example, patents and reference data books provide background information related to the present invention.
The following sources provide information related to peak detectors: (1) National Semiconductor Data Acquisition Databook, Operational Amplifier Databook, Power ICs Databook, and Application Specific Analog Products Databook; (2) Texas Instruments; (3) Fairchild; (4) Encyclopedia of Electronic Circuits, vols. 1-6; (5) Heath/Zenith Continuing Education; Electronic Technology Series; Operational Amplifiers; (6) Electronics Circuit Manual; (7) Linear Technology, 1994 Linear Databook, volume III; and (8) Sourcebook of Electronic Circuits.
Several references, mainly patent documents, provide background information related to position sensors and methods of determining position of an electromechanical device. Generally, these devices range from a modified magnetic circuit that incorporates a magnetic flux sensor to alternating current frequency determination based upon inductive value of the magnetic assembly to physical position indicators.
U.S. Pat. No. 3,089,064 to De Bennetot, entitled Combined Permanent Magnet and Electromagnet, which issued May 7, 1963, shows a Double Pole Double Throw (DPDT) switch controlling the operation of a permanent magnet assembly, which consists of a combination of parallel permanent and electromagnets.
U.S. Pat. No. 3,428,867 to M. C. Becker, entitled Method and Apparatus for Controlling the Useful Magnetornotive Force Of A Permanent Magnet, teaches use of a DPDT switch to control the flow of electrical current in a device using both permanent and electromagnets in a series magnet circuit.
U.S. Pat. No. 3,789,876 to Calvin E. Kempton and Robert H. Reinicke teaches a method of using an alternating current to determine the position of a solenoid armature with any mechanical connections to the armature (solenoid valve with electronic position indicator).
U.S. Pat. No. 4,004,258 to Kurt Arnold teaches a method of modifying the magnetic circuit path to create a flux gap in which a magnetic sensor is used to determine the position of an armature (position indicating latching solenoid).
U.S. Pat. No. 4,059,844 to John W. Stewart demonstrates methods of controlling current to a solenoid (solenoid driver circuit). U.S. Pat. No. 4,262,320 to Lee F. Herron shows a method of operating latching solenoids using an H-switching configuration (H-switch configuration for controlling latching solenoids).
U.S. Pat. No. 4,321,946 to Louis B. Paulos uses a differentiating network to monitor the current flow through a current sensing resistor to control a dual battery driver operating a monostable spring return solenoid to provide visual indicators (armature position monitoring and control device).
U.S. Pat. No. 4,341,241 to Joseph W. Baker uses a mechanical switch to indicate the position of a armature in a valve mechanism (position indicating valve means).
U.S. Pat. No. 4,490,771 to Siefried Huber and Manfred Merkator teaches a method of using an electrical control mechanism to use a portion of the electrical sine wave from a power line to operate a solenoid (control circuit arrangement for an electromagnetically operated power tool).
U.S. Pat. No. 4,620,173 to Robert B. O'Brien shows a method of using magnetic reed switches to show the position of a permanent magnet attached to a solenoid plunger (latching magnetic actuator).
U.S. Pat. No. 4,631,627 to Ronald E. Morgan teaches a method of controlling a relay which operates a motor (impulse operated relay system).
U.S. Pat. No. 4,733,212 to Arthur V. Goodwin, titled Pulse Latching Solenoid, shows a mechanical approach to determining the position of a solenoid armature.
U.S. Pat. No. 4,810,952 to Burton E. Cohen teaches a power delivery method for operating a fastening machine solenoid (circuitry and method for controlling power to fastener machine solenoid).
U.S. Pat. No. 4,810,964 contains a method and apparatus for measuring the distance between a measuring transducer and an opposing surface, particularly with paper pulp equipment.
U.S. Pat. No. 4,950,985 to Thomas Voss et al. teaches a method of determining the position of an armature in a magnetic system by using an alternating current (apparatus for measuring electromagnetic values of a coil, in particular for measuring the position of armature of a coil/armature magnetic system).
U.S. Pat. No. 5,121,018 to Stephen Z. Oldakowski, titled Latching Brake Using Permanent Magnet, teaches the use of parallel electromagnets and permanent magnets in a latching environment to operate a spring applied magnetic release brake operated by a bi-polar pulse.
U.S. Pat. No. 5,632,468 to Ivar Schoenmeyr uses a conventional power supply that rectifies and filters alternating current to provide direct current source of power allowing a solid state switch means to operate a solenoid (Control circuit for solenoid valve).
U.S. Pat. No. 4,970,622 to Josef Bilchl teaches a method of using the slope of the DC charging current energizing an
Bednarek Michael D.
Jackson Stephen W.
Ormanco
Shaw Pittman LLP
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