Resetable battery drain limitation circuit with improved latching relay

A device for limiting current drain from a battery connected to a starter motor and electrical accessories in an engine powered vehicle or the like, the device comprising:

• low voltage detection means for detecting a battery voltage lower than a threshold voltage level;
• interrupting means, responsive to the low voltage detection means, for disconnecting the flow of current from the battery to the starter motor and accessories when the battery voltage is below the threshold voltage;
• reset means for reconnecting the flow of current from said battery to said starter motor and said accessories;
• and
• means for guarding against inadvertent failure of a human operator to reactivate said battery drain limitation device following activation of said reset means, said guarding means further comprising means for reactivating said battery drain limitation device upon activation of said reset means and means for delaying operation of said interrupting means for a preset period of time, said preset period being sufficient to allow starting said engine, said guarding means being usable to operate said accessories in an emergency for said preset period of time.

In an engine powered vehicle or equipment having a battery operated electric starter motor and other electrical accessories, a battery drain limitation device, comprising:

• detection means for determining the existence of a battery drain condition;
• interrupting means, responsive to said detection means, for disconnecting the flow of current from said battery when a battery drain condition is detected;
• reset means for reconnecting the flow of current from said battery to said starter motor and said accessories;
• and
• means for guarding against inadvertent failure of a human operator to reactivate said battery drain limitation device following activation of said reset means, said guarding means further comprising means for reactivating said battery drain limitation device upon activation of said reset means and means for delaying operation of said interrupting means for a preset period of time, said preset period being sufficient to allow starting said engine, said guarding means being usable to operate said accessories in an emergency for said preset period of time.

In an engine powered vehicle or equipment having a battery operated electric starter motor and other electrical accessories, a battery drain limitation device, comprising:

• detection means for determining the existence of a battery drain condition;
• interrupting means, responsive to said detection means, for disconnecting the flow of current from said battery when a battery drain condition is detected, wherein said disconnection protects said battery against current drain from said starter motor and accessories;
• reset means for reconnecting the flow of current from said battery to said starter motor and said accessories;
• delay means for pausing a preset amount of time between detection of said battery drain condition and operation of said interrupting means, said preset amount of time being sufficient to allow starting of said engine;
• and
• reactivation means for reconnecting said battery drain limitation device upon activation of said reset means, said reactivation means in combination with said delay means being usable to operate said accessories in an emergency, said reactivation means providing protection against draining of said battery by inadvertent failure of a human operator to reconnect said battery drain limitation device following activation of said reset means.

A latching relay, comprising:

• a housing containing front and rear annular coils, axially separated by a tubular collar, the housing including front and rear end plates, the collar having a front portion proximate the front coil and a main portion integral with the front portion, the front portion defining an opening with an internal diameter that is larger than that of the main portion, whereby an internal annular shoulder is formed at the juncture between the front and main portions;
• a front plunger slidably disposed between first and second axial positions within the interior of the front coil and the collar, the front plunger including an anterior surface bearing an actuation member that is extensible through an aperture in the front end plate, and a posterior portion defining an axial cavity;
• a rear plunger slidably disposed within the interior of the rear coil and the collar, the rear plunger including an extension member dimensioned and located so as to be insertable into the cavity and axially movable between first and second axial positions therein;
• first biasing means for biasing the front plunger away from the front end plate and toward the rear plunger;
• second biasing means for biasing the rear plunger away from the rear end plate and toward the front plunger;
• and
• latching means, carried in the front plunger so as to be radially movable with respect to the cavity between an inner radial position in which the latching means engage the main portion of the collar, and an outer radial position in which the latching means engage the front portion of the collar and the annular shoulder therein;
• wherein the extension member includes camming means for moving the latching means to the outer radial position when the front plunger is moved toward the front end plate against the force of the first biasing means by the energization of the front coil and the rear plunger is moved by the second biasing means to move the extension member from its first position to its second position within the cavity;
• and
• wherein the latching means move to the inner radial position as the extension member is moved from its second position to its first position when the rear plunger is moved toward the rear end plate against the force of the second biasing means by the energization of the rear coil and the front plunger is moved toward the rear plunger by the first biasing means.

A latching relay, comprising:

• a tubular housing having a front end and a rear end;
• front and rear annular coils axially disposed in the housing, and axially separated by a tubular collar having an interior surface;
• means forming a detent on the interior surface of the collar;
• a front plunger slidably disposed between first and second axial positions within the interior of the front coil and the collar, the front plunger including an anterior surface bearing an elongate actuation arm extensible through the front end of the housing, and a posterior portion defining an axial cavity;
• a rear plunger slidably disposed within the interior of the rear coil and the collar, the rear plunger including an extension member dimensioned and located so as to be insertable into the cavity and axially movable between first and second axial positions therein;
• first biasing means for biasing the front plunger away from the front end of the housing and toward the rear plunger;
• second biasing means for biasing the rear plunger away from the rear end of the housing and toward the front plunger;
• and
• latching means, carried in the front plunger so as to be radially movable with respect to the cavity between an inner radial position in which the latching means engage the interior surface of the collar at a point spaced from the detent thereon, and an outer radial position in which the latching means engage the interior surface of the collar at the detent thereon;
• wherein the extension member includes camming means for moving the latching means to the outer radial position when the front plunger is moved toward the front end of the housing against the force of the first biasing means by the energization of the front coil and the rear plunger is moved by the second biasing means to move the extension member from its first position to its second position within the cavity;
• and
• wherein the latching means move to the inner radial position as the extension member is moved from its second position to its first position when the rear plunger is moved toward the rear end of the housing against the force of the second biasing means by the energization of the rear coil and the front plunger is moved toward the rear plunger by the first biasing means.

In an engine powered vehicle or equipment having a battery operated electric starter motor and other electrical accessories, said battery having a threshold voltage level below which there may not be enough energy in said battery to operate said electric starter motor to start said engine, a battery drain limitation device, comprising:

• a first detection means for determining a low voltage condition on said battery, said low voltage condition being a battery voltage at or below said threshold voltage level;
• a second detection means for determining whether said engine is running;
• interrupting means, responsive to said first and second detection means, for disconnecting the flow of current from said battery when said low voltage condition is detected and when said engine is not running;
• reset means for reconnecting the flow of current from said battery to said starter motor and said accessories;
• and
• means for guarding against inadvertent failure of a human operator to reactivate said battery drain limitation device following activation of said reset means, said guarding means further comprising means for reactivating said battery drain limitation device upon activation of said reset means and means for delaying operation of said interrupting means for a preset-period of time, said preset period being sufficient to allow starting said engine, said guarding means being usable to operate said accessories in an emergency for said preset period of time;
• wherein said first detection means comprises means for setting a stable reference voltage, means for measuring the voltage of said battery relative to said threshold voltage level, said measuring means having a first output voltage, said first output voltage being equal to said stable reference voltage when said battery voltage falls to said threshold level, and first voltage comparing means for determining when said first output voltage is equal to said stable reference voltage,
• wherein said first voltage comparing means comprises first and second inputs and an output, said first voltage comparing means switching its output from low to high when said measuring means outputs said threshold reference voltage to said first input while said stable reference voltage is being applied to said second input via said isolating resistor,
• wherein said interrupting means comprises timing means, first electronic switching means, and relay means,
• wherein said timing means comprises a charging resistor, a timing capacitor and an output, said charging resistor being connected to the output of said first voltage comparing means, said timing capacitor being connected in series with said charging resistor from the output of said first voltage comparing means to ground, and said output being the junction between said charging resistor and said timing capacitor,
• wherein said first electronic switching means comprises a second voltage comparing means, having first and second inputs and an output, first triggering means, means for isolating said output of said second voltage comparing means from said first triggering means, and a first electronic switch, said first input being connected to said output of said timing means and said second input being connected to said stable reference voltage, said output switching state when the output of said timing means exceeds said stable reference voltage, said isolating means having an input and an output and a reset, said input being connected to said output of said second voltage comparing means, said first triggering means having an input and an output, said input being connected to the output of said isolating means, wherein said isolating means, in response to the switched output state of said second voltage comparing means, in turn switches its output to a high state, wherein said first triggering means, in response to the switched output state of said isolating means, outputs a signal which closes said first electronic switch, said first electronic switch thereby connecting a circuit from ground to said relay means,
• wherein said relay means comprise first and second relay coils, contacts and a positive latching means, said relay coils each having upper and lower ends, said first relay coil being activated to unlatch said latching means and open said contacts when said first electronic switch closes, said second relay coil being activated to latch said latching means and close said contacts responsive to said reset means,
• wherein said reset means comprises means for discharging said timing capacitor and means for resetting said isolating means.