Patent Description:
Relays are known in the electrical art as being electromagnetic switches that can receive a control current to operate electrically-isolated electrical contacts to control a separate current path. Therefore, a relay can be used to provide a high degree of electrical isolation between a first circuit (i.e., control circuit) and a second circuit (i.e., load circuit). Moreover, a relay can be used to control a load current (i.e., second circuit) that is significantly larger than the control current (i.e., first circuit). Two known types of relays are conventional relays and latching relays, each having an operating characteristic that can be relevant to a particular application. Therefore, in a manufacturing setting, relays must be procured by specifying the quantities of conventional relays and latching relays that will be required for production of a particular application which uses both types of relays. This can be disadvantageous, particularly when the final circuit application of one or more relays (i.e., conventional or latching) is subject to design changes. Accordingly, there is a need for a system that can control the behavior of an electrical relay having a single design, thereby allowing a particular relay to be programmed to behave as either a conventional relay or as a latching relay. It is cited the patent application <CIT> that discloses an electronic frictional brake system for aircraft that eliminates the need for mechanical components, and allows utilization of a dual input to prevent accidental engagement of the braking system. It is also cited the patent application <CIT> that discloses an optically isolated solid state relay Connecting an external power source to a function selecting input terminal causes the relay to operate as a normally open, normally closed, or latching relay.

The present invention is defined by independent claims.

A method of controlling a behavior of a relay configured for use in electrical circuits that are configured to employ at least one relay, the relay having a first operating mode in which the relay behaves as the conventional relay, and a second operating mode in which the relay behaves as a latching relay, the method comprising:receiving, by a logic controller, a configuration signal comprising either a first behavior signal indicative of the first operating mode or a second behavior signal indicative of the second operating mode receiving, by the logic controller, a power status signal comprising either a powered signal or an unpowerered signal;receiving, by the logic controller, a command signal comprising either a low-to-high signal or a high-to-low signal;generating, by a first pulse generator communicatively coupled to the logic controller, a latching pulse in response to receiving a powered signal input as the power status signal and a low-to-high signal as the command signal input;generating, by a second pulse generator communicatively coupled to the logic controller, an unlatching pulse in response to receiving a powered signal input as the power status signal and a high-to-low signal as the command signal input; andgenerating, by the second pulse generator communicatively coupled to the logic controller, the unlatching pulse in response to receiving the second behavior signal as the configuration signal and the unpowered signal as the power status signal.

A system for controlling a behavior of a relay configured for use in electrical circuits that are configured to employ at least onerelay, the relay having a first operating mode in which the relay behaves as the conventional relay, and a second operating mode in which the relay behaves as a latching relay, the system comprising:a logic controller, configured to receive:a configuration signal input comprising either a first behavior signalindicative of the first operating mode or a second behavior signal indicative of the second operating mode;a power status signal input comprising either a powered signal or anunpowerered signal; anda command signal input comprising either a low-to-high signal or ahigh-to-low signal;a first pulse generator, configured to generate a latching pulse in response toreceiving a powered signal input as the power status signal and a low-to-high signal as the command signal input; anda second pulse generator, configured to generate an unlatching pulse in response to:receiving a powered signal input as the power status signal and a high-to-low signal as the command signal input; orreceiving the second behavior signal as the configuration signal and theunpowered signal as the power status signal.

<FIG> is an electrical schematic diagram of a latching relay of the prior art. Shown in <FIG> are latching relay <NUM>, contactor <NUM>, common contact <NUM>, normally closed contact <NUM>, normally open contact <NUM>, latching control terminal <NUM>, latching coil <NUM>, unlatching control terminal <NUM>, unlatching coil <NUM>, common control terminal <NUM>, and logic state diagram <NUM>. Latching relay <NUM> includes contactor <NUM> which makes electrical contact between common contact <NUM> and either normally closed (NC) contact <NUM> or normally open (NO) contact <NUM>, depending on the condition of latching relay <NUM>, as will be described. When a latching current pulse is applied to latching control terminal <NUM>, latching coil <NUM> is energized thereby drawing contactor <NUM> toward NC contact <NUM>, creating an electrical connection between common contact <NUM> and NC contact <NUM>. Accordingly, latching relay <NUM> is said to be in the latched condition. In the latched condition, there is not an electrical connection between common contact <NUM> and NO contact <NUM>. Latching relay <NUM> is depicted in the latched condition in <FIG>. Latching relay <NUM> transitions to the latched condition during the application of the latching current pulse. Latching relay <NUM> remains in the latched condition after the latching current pulse subsides (i.e., returns to zero). When an unlatching current pulse is applied to unlatching control terminal <NUM>, unlatching coil <NUM> is energized thereby drawing contactor <NUM> toward NO contact <NUM>, creating an electrical connection between common contact <NUM> and NO contact <NUM>. Accordingly, latching relay <NUM> is said to be in the unlatched condition. In the unlatched condition, there is not an electrical connection between common contact <NUM> and NC contact <NUM>. In the illustrated embodiment, common control terminal <NUM> is a ground connection, providing a common signal path for both latching control terminal <NUM> and unlatching control terminal <NUM>.

<FIG> is a logic state diagram for latching relay <NUM> shown in <FIG>. The behavior of latching relay <NUM>, as was described above in regard to <FIG>, is depicted in logic state diagram <NUM>. Latching relay <NUM> can be used when a control system (not shown in <FIG>) generates control pulses that are used to change the condition of latching relay <NUM>. Latching relay <NUM> can be referred to as a bi-stable switch (i.e., having two stable conditions). An advantage of using latching relay <NUM> is that under steady-state conditions (i.e., when not receiving a latching current pulse or an unlatching current pulse), neither latching coil <NUM> nor unlatching coil <NUM> are energized. In some applications, for example, where a power budget is critical, it can be advantageous that latching coil <NUM> and unlatching coil <NUM> remain de-energized during steady-state conditions.

<FIG> is an electrical schematic diagram of a conventional relay of the prior art. Shown in <FIG> are conventional relay <NUM>, contactor <NUM>, common contact <NUM>, normally closed contact <NUM>, normally open contact <NUM>, control terminal <NUM>, control coil <NUM>, and common control terminal <NUM>. Conventional relay <NUM> includes contactor <NUM> which makes electrical contact between common contact <NUM> and normally closed (NC) contact <NUM> or normally open (NO) contact <NUM>, depending on the condition of control coil <NUM>, as will be described. When a control current (i.e., energizing current) is applied to control terminal <NUM>, control coil <NUM> is energized thereby drawing contactor <NUM> toward NO contact <NUM>, creating an electrical connection between common contact <NUM> and NO contact <NUM>. Accordingly, conventional relay <NUM> is said to be in the energized condition. In the energized condition, there is not an electrical connection between common contact <NUM> and NC contact <NUM>. Conventional relay <NUM> remains in the energized condition so long as the control current is applied to control terminal <NUM>. When control terminal <NUM> is de-energized (i.e., the control current is removed), conventional relay <NUM> returns to the de-energized condition. In the de-energized condition, an electrical connection is made between common contact <NUM> and NC contact <NUM>, and the electrical connection between common contact <NUM> and NO contact <NUM> is broken. In a typical embodiment, a mechanical spring (not shown in <FIG>) is compressed by contactor <NUM> when contactor <NUM> is drawn to NO contact <NUM> by control coil <NUM>. Therefore, when control coil <NUM> is de-energized, the mechanical spring forces contactor <NUM> to return to NC contact <NUM>. Conventional relay <NUM> is depicted in the de-energized condition in <FIG>. The de-energized condition can be referred to as the "normal" condition in conventional relay <NUM>, thereby explaining the conventions used in labeling normally closed and normally open contacts (e.g., NC contact <NUM>, NO contact <NUM>). Conventional relay <NUM> can also be referred to as a normal relay. Common control terminal <NUM> is so named because it provides a common (i.e., ground) connection for control coil <NUM>.

<FIG> is a logic state diagram for conventional relay <NUM> shown in <FIG>. The behavior of conventional relay <NUM> as was described above in regard to <FIG> is depicted in logic state diagram <NUM>. Conventional relay <NUM> can be used when a control system (not shown in <FIG>) generates an output current that represents the current that is intended to be supplied to a load. Conventional relay <NUM> can be referred to as a mono-stable switch (i.e., having one stable condition). An advantage of using conventional relay <NUM> is the design simplicity, whereby a control current condition (i.e., on or off) can be used to control a load condition (i.e., on or off). In some applications, for example, where it is desirable that a load remain energized only when a control current is present, it can be advantageous that conventional relay <NUM> return to the normal (i.e., de-energized) condition when the control current is lost.

<FIG> is a schematic block diagram of a relay behavior-changing controller. <FIG> is a logic state diagram for a latching relay connected to the relay behavior-changing controller shown in <FIG>. Shown in <FIG> are controller <NUM>, power status input <NUM>, configuration status input <NUM>, command input <NUM>, configuration logic <NUM>, latching control signal <NUM>, latching pulse generator <NUM>, latching pulse signal <NUM>, unlatching control signal <NUM>, unlatching pulse generator <NUM>, unlatching pulse signal <NUM>, relay system <NUM>, latching coil driver <NUM>, unlatching coil driver <NUM>, configurable relay <NUM>, contactor <NUM>, common contact <NUM>, normally closed contact <NUM>, normally open contact <NUM>, latching control terminal <NUM>, latching coil <NUM>, unlatching control terminal <NUM>, unlatching coil <NUM>, common control terminal <NUM>, and logic state diagram <NUM>. Reference will be made to logic state diagram <NUM> in <FIG> while describing relay system <NUM> in <FIG>. Controller <NUM> can be referred to as a control circuit or as a relay behavior-changing controller. Configuration logic <NUM> within controller <NUM> receives three input signals: power status input <NUM>, configuration status input <NUM>, and command input <NUM>. A description will first be made of the operation of other aspects of control circuit <NUM> within relay system <NUM>. Configuration logic <NUM> (i.e., "config logic") is configured to produce latching control signal <NUM> and unlatching control signal <NUM> when it is desired to latch or unlatch configurable relay <NUM>, respectively. Latching control signal <NUM>, when generated, is input to latching pulse generator <NUM> which in turn provides latching pulse signal <NUM> to latching coil driver <NUM>, thereby delivering a latching current pulse to latching control terminal <NUM> of configurable relay <NUM>. In an similar manner, unlatching control signal <NUM>, when generated, is input to unlatching pulse generator <NUM> which in turn provides unlatching pulse signal <NUM> to unlatching coil driver <NUM>, thereby delivering an unlatching current pulse to unlatching control terminal <NUM> of configurable relay <NUM>. Latching and unlatching pulse generators <NUM>, <NUM> can be referred to as monostable multivibrators or as "one-shots", because they generate an output pulse of a defined duration when triggered, then return to their resting condition. In the illustrated embodiment, configurable relay <NUM> is a latching relay at the component level. A latching relay can also be referred to as a bi-stable relay, as a "keep" relay", and as a "stay" relay, because it keeps (i.e., stays) in a particular condition after being activated by a signal (e.g., latch or unlatch signal).

Configurable relay <NUM> includes contactor <NUM> which makes an electrical contact via contactor <NUM> between common contact <NUM> and either normally closed (NC) contact <NUM> or normally open (NO) contact <NUM>, depending on the condition of configurable relay <NUM>. When a latching current pulse is applied to latching control terminal <NUM>, latching coil <NUM> is energized thereby drawing contactor <NUM> toward NC contact <NUM>, creating an electrical connection between common contact <NUM> and NC contact <NUM>. Accordingly, configurable relay <NUM> can be said to be latched, or in a latched condition. The latched condition can also be referred to as a first condition. When configurable relay <NUM> is latched, there is not an electrical connection between common contact <NUM> and NO contact <NUM>. Configurable relay <NUM> is depicted in the latched (i.e., first) condition in <FIG>. When an unlatching current pulse is applied to unlatching control terminal <NUM>, unlatching coil <NUM> is energized thereby drawing contactor <NUM> toward NO contact <NUM>, creating an electrical connection between common contact <NUM> and NO contact <NUM>. Accordingly, relay <NUM> is said to be in the unlatched condition. The unlatched condition can also be referred to as a second condition. When configurable relay <NUM> is in the unlatched condition, there is not an electrical connection between common contact <NUM> and NC contact <NUM>. In the illustrated embodiment, common control terminal <NUM> is a ground connection, providing a common signal path for both latching control terminal <NUM> and unlatching control terminal <NUM>.

As noted earlier, configurable relay <NUM> includes common contact <NUM> which makes an electrical connection via contactor <NUM> with either NC contact <NUM> or NO contact <NUM>. Configurable relay <NUM> can be described as having a single switching pole, and as being a single-pole double-throw (SPDT) switch. In some embodiments, more than a single switching pole (i.e., pole) of contacts can be used. For example, two switching poles (i.e., two contactors <NUM>) can be connected by a common actuator (not shown in <FIG>), resulting in a double-pole double-throw (DPDT) switch. Typically, each switching pole will have a separate contactor <NUM> that is electrically isolated from the others. A two-pole relay (i.e., DPDT) can be used to control two load circuits (not shown in <FIG>). In an exemplary DPDT embodiment, a first pole can control a load current, and a second pole can control a feedback circuit that provides an indication of the condition of configurable relay <NUM> to a different circuit (not shown in <FIG>). In other embodiments, three or more poles can be used in configurable relay <NUM>. In these other embodiments, configurable relay <NUM> can be referred to as an NPDT switch where N represents the number of switching poles, which can include any number of switching poles. The present disclosure includes any number of switching poles in configurable relay <NUM>. In any of these embodiments, either NC contact <NUM> or NO contact <NUM> can be omitted from one or more switching poles of configurable relay <NUM>. In an exemplary embodiment, configurable relay <NUM> can include a single switching pole having common contact <NUM> and a single other contact (i.e., either NC contact <NUM> or NO contact <NUM>). In this exemplary embodiment, configurable relay <NUM> can be referred to as a single-pole single-throw (SPST) switch.

Referring again to <FIG>, configuration logic <NUM> can receive power status input <NUM>, configuration status input <NUM>, and command input <NUM>, as noted earlier. Power status input is either "powered" or "unpowered" (i.e., loss of power). Configuration status input <NUM> is either "conventional" (i.e., normal) or "latching", depending on the relay type that configurable relay <NUM> is configured to behave as. Providing a "conventional" input at configuration status input <NUM> can be referred to as a first operating condition of configurable relay <NUM>, and providing a "latching" input at configuration status input <NUM> can be referred to as a second operating condition of configurable relay <NUM>. Command input <NUM> is either a "low-to-high" or a "high-to-low" signal transition, as desired to change the condition of configurable relay <NUM>. The behavior of configurable relay <NUM> can be made to function as a latching relay by providing a "latching" input at configuration status input <NUM>. Under the "latching" input condition, an unpowered (i.e., loss of power) input at power status input <NUM> has no effect, and configuration logic <NUM> does not produce any signal output. Accordingly, the position of contactor <NUM> in configurable relay <NUM> does not change when power status input is unpowered (i.e., loss of power), and the configuration of common contact <NUM>, NC contact <NUM>, and NO contact <NUM> remains the same as shown in logic state diagram <NUM>. When control circuit <NUM> is configured for configurable relay <NUM> to emulate the function of a conventional relay (i.e., configuration status input <NUM> is "conventional"), a powered input signal at power status input <NUM> will cause configuration logic <NUM> to generate an output signal at latching control signal <NUM>, thereby directing a latching current pulse to latching coil <NUM>. When the powered input signal is removed at power status input <NUM> (i.e., loss of power), configuration logic <NUM> will generate an output signal at unlatching control signal <NUM>, thereby directing an unlatching current pulse to unlatching coil <NUM>, as described above.

Providing a "latching" input at configuration status input <NUM> will configure control circuit <NUM> to emulate the function of a latching relay (i.e., the second operating condition of configurable relay <NUM>). Accordingly, a "low-to-high" signal at command input <NUM> will cause configuration logic <NUM> to produce latching control signal <NUM>, thereby directing a latching current pulse to latching coil <NUM>, causing configurable relay <NUM> to transition to a latched condition as described above. Similarly, a "high-to-low" signal at command input <NUM> will cause configuration logic <NUM> to produce unlatching control signal <NUM>, thereby directing an unlatching current pulse to unlatching coil <NUM>, causing configurable relay <NUM> to transition to an unlatched condition as described above. In the illustrated embodiment, with a powered input to power status input <NUM> indicating the system is powered, the input signal applied to configuration status input <NUM> has no bearing and the control of configurable relay <NUM> is driven by the input at command input <NUM>. Accordingly, logic state diagram <NUM> provides an asterisk in the Config column (i.e., configuration status input <NUM>) denoting that configuration status input 74is irrelevant. Controller <NUM> of the present embodiment is particularly adapted for a latch-unlatch signal residing on a single input line (i.e., command input <NUM>). In other embodiments, controller <NUM> can be adapted to receive discrete "latch" and "unlatch" signals. Being a latching relay, configurable relay <NUM> requires two commands to function (i.e., latch and unlatch). In contrast, a conventional relay requires only one input (i.e., a voltage applied to a control terminal). The reason a latching relay requires an input command (i.e., a latch or unlatch command) is the internal bi-stable design of the latching relay that requires and allows for the latching relay to remain in an existing state (i.e., latched or unlatched) when power is removed. Accordingly, controller <NUM> allows configurable relay <NUM> (i.e., a latching relay) to emulate the behavior of a conventional relay when configuration status input <NUM> is "normal" (i.e., conventional). In other words, controller <NUM> allows a latching relay to be used as a conventional relay, if so desired. The only condition under which configuration status input <NUM> matters is during the time surrounding a loss of power. At the moment when controller <NUM> detects power is being lost, configuration logic <NUM> uses configuration status input <NUM> to determine in what state to leave configurable relay <NUM> when power is eventually lost (i.e., latched or unlatched). If configuration status input <NUM> is "latching", then configuration logic <NUM> leaves configurable relay <NUM> in its current state (i.e., latched or unlatched). If configuration status input <NUM> is "conventional", then, at the point of power loss, configuration logic <NUM> commands will command configurable relay <NUM> to the NO condition (i.e., unlatched), thereby emulating a conventional relay. The behavior of configurable relay <NUM> can be controlled at any time during the operation of relay system <NUM> by changing the input to configuration status input <NUM> (i.e., from "conventional" to "latching", or from "latching" to "conventional"). Accordingly, configurable relay <NUM> can be said to be reconfigurable "on the fly" during the operation of relay system <NUM>, thereby providing operational flexibility.

Claim 1:
A method of controlling a behavior of a relay configured for use in electrical circuits that are configured to employ at least one relay (<NUM>), the relay having a first operating mode in which the relay behaves as the conventional relay, and a second operating mode in which the relay behaves as a latching relay, the method comprising:
receiving, by a logic controller (<NUM>), a configuration signal (<NUM>) comprising either a first behavior signal indicative of the first operating mode or a second behavior signal indicative of the second operating mode;
receiving, by the logic controller, a power status signal (<NUM>) comprising either a powered signal or an unpowerered signal;
receiving, by the logic controller, a command signal (<NUM>) comprising either a low-to-high signal or a high-to-low signal;
generating, by a first pulse generator (<NUM>) communicatively coupled to the logic controller, a latching pulse in response to receiving a powered signal input as the power status signal and a low-to-high signal as the command signal input;
generating, by a second pulse generator (<NUM>) communicatively coupled to the logic controller, an unlatching pulse in response to receiving a powered signal input as the power status signal and a high-to-low signal as the command signal input; and
generating, by the second pulse generator communicatively coupled to the logic controller, the unlatching pulse in response to receiving the second behavior signal as the configuration signal and the unpowered signal as the power status signal.