Patent Description:
The present disclosure generally relates to the field of aircraft and, more particularly, to cable cutters for an aircraft hoist.

The helicopter airborne rescue mission may utilize a hoist cable. A typical hoist cable uses stainless steel rope attached to a cable drum of the hoist at one end and a hook at the other. This cable shares the load of rescuers or the rescuing items and the causalities. The cable should withstand being reeled in and reeled out from the hoist drum. Existing hoists include an option for cutting the cable. For instance, during rescue operations the cable may fail due to overload or the cable may be defective, such that it would be desirable to cut the cable "above" the damaged area. Moreover, it may be desirable to cut the cable if the cable gets stuck during a rescue operation. Existing hoist systems currently use an electric squib-based cable cutter for cutting the cable. This electric squib initiator uses explosive materials to generate the force required to cut the cable. That is, the electrical energization of the squib generates pressurized gas that acts on a movable piston that incorporates a cutter knife (a "cutter-piston"). Generation of this force is very fast and the cutter-piston experiences rapid sliding movement such that the cutter knife edge cuts/servers the cable.

Document <CIT> discloses such a cable cutter assembly for a hoist.

The major drawbacks of the above-noted squib-based cable cutter are the regulatory issues because of the explosive material that is utilized. Moreover, this is single shot initiator device and has no built-in test features. This squib-based cable cutter also cannot be shipped as a part of the hoist as it contains explosive. Being an explosive-type initiator, it may be susceptible to inadvertent firing due to mechanically abusive loads as well.

A cable cutter assembly for a hoist is presented herein. Both the configuration of such a cable cutter assembly and the operational characteristics / operation of such a cable cutter assembly are within the scope of this Summary.

One aspect provides a cable cutter assembly as defined by claim <NUM>.

This hoist may be incorporated by an aircraft of any appropriate size, shape, configuration, and/or type and including without limitation a helicopter. The body may include a first pressurized fluid cavity and a first fluid passage that extends from the first pressurized fluid cavity. The armature may include a second fluid passage that is fluidly interconnected with the first fluid passage, and with the armature being movable between a first position and a second position. An air gap may exist between the armature and the body at least when the solenoid/armature is in the first position. A second pressurized fluid cavity may be fluidly interconnected with the first fluid passage (and thereby the first pressurized fluid cavity) by the second fluid passage. The actuator assembly may include at least one outlet port (e.g., a first outlet port). The armature (e.g., a valve seal incorporated by the armature) may engage the first outlet port when the armature is in the first position. Disposing the armature in the second position (e.g., via energizing the coil) may dispose the armature in spaced relation to the first outlet port, fluidly connect the second pressurized fluid cavity with the cutter body cavity, and move the cutter in a cable cutting direction.

Another aspect is embodied by a method of operating an aircraft hoist assembly using the cable cutter as defined by claim <NUM>.

An understanding of the present disclosure may be further facilitated by referring to the following detailed description and claims in connection with the following drawings. Reference to "in accordance with various embodiments" in this Brief Description of the Drawings also applies to the corresponding discussion in the Detailed Description.

An exemplary hoist and hook system <NUM> is shown in <FIG> and is identified by reference numeral <NUM>. The hoist and hook system <NUM> includes a hoist assembly <NUM> that is mechanically coupled to an airframe or aircraft <NUM> (e.g., a helicopter or any other appropriate aircraft). The hoist assembly <NUM> may be coupled directly to the airframe <NUM> or may be mechanically coupled to a boom that in turn is mechanically coupled to the airframe <NUM>. In any case, a cable <NUM> may be wound about a drum within the hoist assembly <NUM> and deployed or retracted based on the rotational direction of the drum. The cable <NUM> may thus hang at various distances from the hoist assembly <NUM> and airframe <NUM>. A hook assembly <NUM> may be coupled to a free end of the cable <NUM> opposite the drum for the hoist assembly <NUM>. The hook assembly <NUM> may hang from the hoist assembly <NUM> on the cable <NUM>. The cable <NUM> and hoist assembly <NUM> may thus swing and/or translate relative to the hoist assembly <NUM> and the airframe <NUM>. The position of the hoist assembly <NUM> may be controlled in part by changing the position of the hoist assembly <NUM> and/or the airframe <NUM>.

A cable cutter assembly that may be used in combination with a hoist (e.g., hoist assembly <NUM> - <FIG>) is illustrated in <FIG>, is identified by reference numeral <NUM>, and extends along a longitudinal axis <NUM> (corresponding with a longitudinal or length dimension for the cable cutter assembly <NUM> and the various components thereof). The cable cutter assembly <NUM> may be used to cut/sever a rope, tether, or cable (hereafter "cable") for a hoist/hoist assembly (e.g., cable <NUM> - <FIG>) for a hoist (e.g., hoist assembly <NUM> - <FIG>) used by an aircraft (e.g., aircraft <NUM> - <FIG>). The cable cutter assembly <NUM> includes what may be characterized as an actuator assembly <NUM> (e.g., in the form of a solenoid; utilizing a coil <NUM> and an armature or plunger <NUM>) and a cutter assembly <NUM>. Generally, the actuator assembly <NUM> includes a pressurized fluid with a valve (e.g., a solenoid valve) that is selectively movable/actuated between closed and open positions. Moving the valve to the open position releases the pressurized fluid to exert a fluid pressure on the cutter assembly <NUM> to in turn move a portion of the cutter assembly <NUM> to engage and cut/sever a cable of any appropriate configuration and formed from any appropriate material or combination of materials (e.g., stainless steel).

The actuator assembly <NUM> may be characterized as including a housing assembly <NUM>. The housing assembly <NUM> may include a first housing section <NUM>, a second housing section <NUM>, and an outlet fitting <NUM> on a distal end of the housing assembly <NUM>. A body or solenoid body <NUM> (e.g., a fixed core) is partially disposed within the housing assembly <NUM>. The solenoid body <NUM> includes a first pressurized fluid cavity <NUM> and a first fluid passage <NUM> that extends from the first pressurized fluid cavity <NUM> at least generally in the direction of the outlet fitting <NUM> (e.g., in the longitudinal dimension). A proximal portion of the solenoid body <NUM> extends proximally of the housing assembly <NUM> (e.g., in the longitudinal dimension). A pressure sensor <NUM> of any appropriate type (e.g., a MEMS device) may be operatively interconnected with the first pressurized fluid cavity <NUM> (e.g., on a portion of the solenoid body <NUM> that is disposed proximally of the housing assembly <NUM>). An appropriate pressurized fluid (e.g., one or more gases, and including air) may be directed into the first pressurized fluid cavity <NUM> through a fill valve <NUM>. The fill valve <NUM> is located on a portion of the solenoid body <NUM> that is disposed proximally of the housing assembly <NUM> to accommodate "re-filling" of the first pressurized fluid cavity <NUM> (or more generally the actuator assembly <NUM>) with a pressurized fluid, for instance after the cable cutter assembly <NUM> has been operated to cut a cable or to address the case of a leakage. A plug <NUM> may be used to retain the pressurized fluid within the first pressurized fluid cavity <NUM> (or more generally within the actuator assembly <NUM>). A coil <NUM> is disposed about at least a portion of the solenoid body <NUM>. The coil <NUM> may be enclosed between the first housing section <NUM> of the housing assembly <NUM> and the solenoid body <NUM>.

The first fluid passage <NUM> for the solenoid body <NUM> may be characterized as including a first longitudinal passage segment or section <NUM>, a second longitudinal passage segment or section <NUM>, and a third longitudinal passage segment or section <NUM>, with the second longitudinal passage segment <NUM> being disposed between the first longitudinal passage segment <NUM> and the third longitudinal passage segment <NUM> (each such longitudinal passage segment having a length that proceeds at least generally in the noted longitudinal dimension and that would coincide with a direction of flow along/through a corresponding longitudinal passage segment). An outer diameter of the first longitudinal passage segment <NUM> may be larger than an outer diameter of the second longitudinal passage segment <NUM>. An outer diameter of the third longitudinal passage segment <NUM> may be larger than an outer diameter of at least one of the first longitudinal passage segment <NUM> and the second longitudinal passage segment <NUM>. <FIG> and <FIG> illustrate the third longitudinal passage segment <NUM> as having a larger outer diameter than both the first longitudinal passage segment <NUM> and the second longitudinal passage segment <NUM>.

An armature or plunger <NUM> is movably interconnected with the solenoid body <NUM> for movement relative to the solenoid body <NUM> along the longitudinal axis <NUM> of the cable cutter assembly <NUM>, with a proximal portion of the armature <NUM> being disposed within the third longitudinal passage segment <NUM> of the solenoid body <NUM>. A spring <NUM> is also disposed within the third longitudinal passage segment <NUM> of the solenoid body <NUM> and biases the armature <NUM> along the longitudinal axis <NUM> in the direction of the outlet fitting <NUM>. A non-magnetic spacer <NUM> may be disposed between a corresponding portion of the armature <NUM> and the coil <NUM>. The armature <NUM> and coil <NUM> may be collectively referred to as a solenoid.

A second fluid passage <NUM> extends through the armature <NUM> and proceeds at least generally along the longitudinal or length dimension of the cable cutter assembly <NUM>. A first longitudinal passage segment <NUM> of the second fluid passage <NUM> (armature <NUM>) extends from the third longitudinal passage segment <NUM> of the first fluid passage <NUM> (solenoid body <NUM>). One or more second longitudinal passage segments <NUM> of the second fluid passage <NUM> extend from its first longitudinal passage segment <NUM> to a second pressurized fluid cavity <NUM> (in diverging relation to the longitudinal axis <NUM> proceed from the third longitudinal passage segment <NUM> of the first fluid passage <NUM> (solenoid body <NUM>) to the second pressurized fluid cavity <NUM>). The second pressurized fluid cavity <NUM> may be defined by the space between a distal section of the armature <NUM> and the housing assembly <NUM> (e.g., the second housing section <NUM>). In any case, the second pressurized fluid cavity <NUM> is fluidly connected with the first pressurized fluid cavity <NUM> by the first fluid passage <NUM> (solenoid body <NUM>) and the second fluid passage <NUM> (armature <NUM>). A common pressurized fluid should thereby be disposed within the first pressurized fluid cavity <NUM>, second pressurized fluid cavity <NUM>, first fluid passage <NUM> (solenoid body <NUM>), and second fluid passage <NUM> (armature <NUM>). The first pressurized fluid cavity <NUM>, second pressurized fluid cavity <NUM>, first fluid passage <NUM> (solenoid body <NUM>), and second fluid passage <NUM> (armature <NUM>) may be characterized as collectively defining a pressurized fluid source for the actuator assembly <NUM>. Moreover, the first pressurized fluid cavity <NUM>, second pressurized fluid cavity <NUM>, first fluid passage <NUM> (solenoid body <NUM>), and second fluid passage <NUM> (armature <NUM>) should be at a common static pressure (e.g., prior to initiating operation of the actuator assembly <NUM>; prior to applying a voltage to/energizing the coil <NUM>).

When the actuator assembly <NUM> or armature <NUM> is in a first or closed position (<FIG>), a distal end of the armature <NUM> (that includes a valve seal <NUM>) engages the outlet fitting <NUM> to block fluid communication of the second pressurized fluid cavity <NUM> with an outlet port <NUM> that extends through the outlet fitting <NUM>. At this time (when the actuator assembly <NUM>/armature <NUM> is in the first/closed position of <FIG>), there is a first air gap <NUM> and a second air gap <NUM> between the armature <NUM> and the solenoid body <NUM>.

When the actuator assembly <NUM> or armature <NUM> is in a second or open position (<FIG>), via operation of the coil <NUM> (when at least a certain voltage is applied to the coil <NUM>; when the coil <NUM> is disposed in an energized state) and a resulting compression of the spring <NUM> by a movement of the armature <NUM> relative to the solenoid body <NUM> away from the outlet fitting <NUM> provided by a magnetic force exerted on the armature <NUM>, the valve seal <NUM> of the armature <NUM> is spaced from the outlet fitting <NUM> to allow pressurized fluid to flow from the second pressurized fluid cavity <NUM> through the outlet port <NUM> of the outlet fitting <NUM>. The size of the first air gap <NUM> and second air gap <NUM> between the armature <NUM> and the solenoid body <NUM> is at least reduced when the actuator assembly <NUM>/armature <NUM> is in the second/open position of <FIG> in comparison to the first/closed position of <FIG>.

Based upon the forgoing, the armature <NUM> may be characterized as being a valve that is movable between a first/closed position (<FIG>) to isolate a pressurized fluid (or to isolate a pressurized fluid source of the actuator assembly <NUM>) from the cutter assembly <NUM>, and a second/open position (<FIG>) to accommodate a flow of pressurized fluid into the cutter assembly <NUM> (or to fluidly connect a pressurized fluid source of the actuator assembly <NUM> with the cutter assembly <NUM>). Movement of the armature <NUM> from the first/closed position of <FIG> to the second/open of <FIG> is realized by operation of the actuator assembly <NUM>, namely by applying at least a certain voltage (e.g., a threshold voltage) to the coil <NUM> (e.g., disposing the coil <NUM> in an energized state) to create a magnetic field that exerts a force on the armature <NUM> to move the armature <NUM> in the above noted manner (e.g., along the longitudinal axis <NUM> in a direction that is away from the outlet fitting <NUM>). When the magnetic field is released (e.g., when the coil <NUM> is returned to a de-energized state), the spring <NUM> moves the armature <NUM>, along the longitudinal axis <NUM> and relative to the solenoid body <NUM>, back to the first/closed position of <FIG>.

The cutter assembly <NUM> may be characterized as being disposed at a distal end of the housing assembly <NUM> and disposed about the outlet fitting <NUM>. The cutter assembly <NUM> includes a cutter body <NUM> having a cutter body cavity <NUM> that is fluidly connected with the outlet port <NUM> of the outlet fitting <NUM>. A cutter or piston <NUM> is movably disposed within the cutter body cavity <NUM>. One or more seals <NUM> (e.g., an O-ring) may be provided between an outer perimeter of the cutter <NUM> and an outer perimeter of the cutter body cavity <NUM> that is defined by the cutter body <NUM>.

At least one latch or shear pin <NUM> may maintain the cutter <NUM> in a fixed position relative to the cutter body <NUM>, where the cutter <NUM> is spaced from an anvil or stopper <NUM> at a distal end of the cutter body cavity <NUM>. A cable <NUM> may extend through the cutter body cavity <NUM> at a location that is between the cutter <NUM> and the anvil <NUM>. The cutter <NUM> may include at least one cutter knife edge <NUM> for cutting through/severing the cable <NUM> in response to operation of the actuator assembly <NUM> to move the cutter <NUM> relative to the cutter body <NUM> and toward the cable <NUM>/anvil <NUM> (after each latch pin <NUM> has been disabled/sheared/ruptured/broken).

When the actuator assembly <NUM>/armature <NUM> is in the first/closed position of <FIG>, the cutter body cavity <NUM> should be fluidly isolated from the second pressurized fluid cavity <NUM>. The existence of a leak from the second pressurized fluid cavity <NUM> into the cutter body cavity <NUM> could adversely affect the ability of the cable cutter assembly <NUM> to cut through/sever the cable <NUM> in the desired manner and/or could result in inadvertent actuation of the cutter <NUM>. In this regard, one or more leak vent fittings <NUM> may be fluidly connectable with the cutter body cavity <NUM>, with each leak vent fitting <NUM> including one or more leak ports <NUM>. This fitting <NUM> may incorporate features to prevent the ingress of media from the external ambience to within the cutter body cavity <NUM>.

Referring now to <FIG>, an elastomeric sleeve <NUM> may be disposed over at least one leak port <NUM> of a leak vent fitting <NUM>. Accumulation of the leaked gas pressure within the cutter body cavity <NUM> will push this sleeve <NUM> radially out (<FIG>) and vent the gas through the narrow passages formed in the elastomeric sleeve <NUM> (these passages "opening" in response to stretching of the sleeve <NUM>). Once the leaked gas is vented to the external ambient, the pressure in the cutter body cavity <NUM> drops and the elastomeric sleeve(s) <NUM> returns back to the original state (<FIG>) to reduce the potential of external media entering the cutter body cavity <NUM> (e.g., by the noted passage(s) in the sleeve <NUM> closing by the noted contraction of the sleeve <NUM>).

Referring back to <FIG>, it again shows the actuator assembly <NUM> using dual air gaps and being in a de-energized state. The actuator assembly <NUM> may be characterized as utilizing a fast-acting type solenoid (at least the coil <NUM> and armature <NUM>) with an inline, normally closed solenoid valve (e.g., the distal end of the armature <NUM> with the valve seal <NUM>). The armature <NUM> is of a flat disc-shaped type and includes the second fluid passage <NUM>. The valving unit or valve seal <NUM> on the distal end of the armature <NUM> is a flat poppet type. For valve leak tightness, the valve seal <NUM> uses a soft valve seal and is retained in a cavity on the distal end of the armature <NUM>.

The solenoid coil <NUM> is again disposed between the solenoid body <NUM> and the housing assembly <NUM>. The working air gaps <NUM>, <NUM> are defined between the body pole faces and the flat faces of the armature <NUM>. The magnetic flux path, when the solenoid coil <NUM> is energized, proceeds about the coil <NUM> (via the body of the armature <NUM>) and passes through the two air gaps <NUM>, <NUM>. As shown, the inlet side of the actuator assembly <NUM> is provided with cavity volume (first pressurized fluid cavity <NUM>) which may be "filled" or loaded with a pressurized fluid (e.g., one or more gases) using the fill valve <NUM> (e.g., of a miniature type) assembled to the extreme inlet side. This cavity fluid pressure may be monitored using the pressure sensor <NUM>, which is attached to the solenoid body <NUM>. The inlet of the fill valve <NUM> may be incorporate a plug <NUM> to provide a leak-tight seal. In the solenoid de-energized state, the valve seal <NUM> is loaded by the solenoid spring force (spring <NUM>) and the unbalanced fluid pressure acting at the valve sealing area. The valve seat is provided within the outlet fitting <NUM>. This way, the valve seal <NUM> is stressed to the seating region in the outlet fitting <NUM>. By suitable seal design, stringent leak tightness may be achieved.

When the solenoid is energized (more specifically, the coil <NUM>), the armature <NUM> along with valve seal <NUM> are moved to solenoid pole face, such that the air gaps <NUM>, <NUM> are reduced to a minimum value. This creates the solenoid valve opening as shown in the <FIG>. Upon the opening of the solenoid valve (e.g., the distal end of the armature <NUM>), the pressurized fluid stored (e.g., pneumatic medium gas) in the first pressurized fluid cavity <NUM>, the first fluid passage <NUM>, the second fluid passage <NUM> and the second pressurized fluid cavity <NUM> gets discharged through the outlet port <NUM> into the cutter body cavity <NUM>.

The downstream portion of the solenoid valve is assembled with the cutter body <NUM>, which houses the cutter/piston <NUM>. The cutter <NUM> may use a radial O ring seal <NUM> and it is latched/secured using at least one latch or shear pin <NUM> in the pre-firing phase. The fluid charging and the gas pressure build up in the cutter body cavity <NUM> replicates the gas pressure built up by the firing of an electric squib-type cable cutter. The pressure acting at the piston O-ring seal <NUM> develops the pressure force. This force value increases and ruptures the corresponding latch/shear pin(s) <NUM>. By this, the cutter <NUM> experiences "snap acceleration" movement toward the cable <NUM>.

Summarizing the foregoing, <FIG> shows the first/closed position for the actuator assembly <NUM>/armature <NUM>, where the valve seal <NUM> of the armature <NUM> engages the outlet fitting <NUM>, preferably such that there is no or only minimal/insignificant leakage from the second pressurized fluid cavity <NUM> into the cutter body cavity <NUM>. The pressure of the pressurized fluid should be constant throughout the first pressurized fluid cavity <NUM>, the first fluid passage <NUM>, the second fluid passage <NUM>, and the second pressurized fluid cavity <NUM>. At this time, the coil <NUM> is not exerting a force on the armature <NUM> (e.g., the coil <NUM> is in a de-energized state), but the spring <NUM> is exerting a force on the armature <NUM> to dispose the valve seal <NUM> in fluid sealing engagement with the outlet fitting <NUM> (e.g., to fluidly isolate the second pressurized fluid cavity <NUM> from the cutter body cavity <NUM>). Moreover, there is a net unbalanced fluid pressure force when the coil <NUM> is in a de-energized state. Taking the entire valve inner cavity, namely the first pressurized fluid cavity <NUM>, the first fluid passage <NUM>, the second fluid passage <NUM>, and the second pressurized fluid cavity <NUM>, the net pressure unbalanced region is in the area equivalent to the outer diameter of the outlet fitting <NUM> (or a seat land, for instance formed from metal and that interfaces with a softer valve seal <NUM>) and that is exposed to fluid pressure. The fluid pressure load in this area aids in disposing the actuator assembly <NUM>/armature <NUM> in the first/closed position (<FIG>). As such, the sum of the spring force (spring <NUM>) and this unbalanced fluid pressure force provides the total closing/sealing force for the actuator assembly <NUM>/armature <NUM>.

Activation of actuator assembly <NUM>, namely by applying at least a certain voltage to the coil <NUM> (e.g., disposing the coil <NUM> in an energized state), creates a magnet field that exerts a magnetic force on the armature <NUM> to move the armature <NUM> along the longitudinal axis <NUM> from the first/closed position of <FIG> into the second/open position of <FIG> (and against the biasing force of the spring <NUM>), such that the valve seal <NUM> (armature <NUM>) is now spaced from the outlet fitting <NUM>. As such, pressurized fluid (within the first pressurized fluid cavity <NUM>, the first fluid passage <NUM>, the second fluid passage <NUM> and the second pressurized fluid cavity <NUM>) may flow from the second pressurized fluid cavity <NUM>, through the outlet port <NUM> of the outlet fitting <NUM>, and into the cutter body cavity <NUM> to exert a fluid pressure on the cutter <NUM> that is directed toward the cable <NUM> and the anvil <NUM>. Once the pressure within the cutter body cavity <NUM> satisfies a certain pressure threshold, each latch pin <NUM> should be disabled/sheared/ruptured/broken to allow the cutter <NUM> to advance in the direction of and to cut/sever the cable <NUM> (e.g., to separate the hook assembly <NUM> from the remainder of the hoist assembly <NUM> and also from the airframe <NUM> - <FIG>).

A variation of the cable cutter assembly <NUM> of <FIG> is illustrated in <FIG> and is identified by reference numeral <NUM>'. Corresponding components between the cable cutter assembly <NUM> and the cable cutter assembly <NUM>' are identified by the same reference numerals. Those corresponding components that differ between the cable cutter assembly <NUM> and the cable cutter assembly <NUM>' are further identified by "single prime" designation with regard to the cable cutter assembly <NUM>' of <FIG>. By way of initial summary, the cable cutter assembly <NUM> (<FIG>) may be characterized as using dual working air gaps, while the cable cutter assembly <NUM>' (<FIG>) may be characterized as using a single air gap. The response time for moving the armature <NUM> from the first/closed position of <FIG> to the second/open position of <FIG> may be faster than the response time for moving the armature <NUM>' from the first/closed position of <FIG> to the second/open position of <FIG>. Otherwise, the cable cutter assembly <NUM>' may be viewed as substantially corresponding with the cable cutter assembly <NUM>'.

The following components of the cable cutter assembly <NUM>' of <FIG> differ (e.g., structurally and/or sizing) from the corresponding component of the cable cutter assembly <NUM> of <FIG>: actuator assembly <NUM>'; housing assembly <NUM>'; first housing section <NUM>'; body or solenoid body <NUM>'; non-magnetic spacer(s) <NUM>'; armature or plunger <NUM>'; and air gap <NUM>'. The cutter assembly <NUM>' of <FIG> also differs from the cutter assembly <NUM> of <FIG>, including in relation to how the cutter assembly <NUM>' is integrated with the actuator assembly <NUM>'. As such, the cutter body <NUM>', cutter body cavity <NUM>', the cutter or piston <NUM>' and cutter knife edge <NUM>' of <FIG> differ (e.g., structurally and/or sizing) from the corresponding component(s) of the cable cutter assembly of <FIG>.

In the de-energized state or condition (<FIG>), the fluid pressure is continuously acting at the valve seal <NUM> (of the armature <NUM>') and the leak tightness (e.g., a hermetic seal) is maintained. By suitable design, the valve seal <NUM> may be fully contained within a metallic cavity on the end of the armature <NUM>' and cold flow of the valve seal <NUM> can be eliminated. By providing appropriate sealing stress, it is possible to achieve seal leak tightness in the range of <NUM>-<NUM> scc/sec of GHe and possible to maintain this leak tightness for long operating periods of <NUM> to <NUM> years, for instance. The specified or the allowed minute gas leak flow can eventually get "filled" in the downstream cutter body cavity <NUM>'. The accumulation of this leaked fluid eventually builds up pressure and could cause inadvertent actuation of the cutter <NUM>'. In order to reduce the potential for inadvertent actuation of the cutter <NUM>', this leaked gas again may be vented to the external ambient using the above-noted leak vent fitting(s) <NUM> (fluidly connected with the cutter body cavity <NUM>') and the corresponding discussion presented above on <FIG>.

The cable cutter assembly <NUM>' operates at least generally in accord with the cable cutter assembly <NUM> of <FIG>. <FIG> shows the first/closed position for the actuator assembly <NUM>'/armature <NUM>', where the valve seal <NUM> of the armature <NUM>' engages the outlet fitting <NUM>', preferably such that there is no or only minimal/insignificant leakage from the second pressurized fluid cavity <NUM> into the cutter body cavity <NUM>'. The pressure of the pressurized fluid should be constant throughout the first pressurized fluid cavity <NUM>, the first fluid passage <NUM>, the second fluid passage <NUM>, and the second pressurized fluid cavity <NUM>. At this time, the coil <NUM> is not exerting a force on the armature <NUM>' (e.g., the coil <NUM> is in a de-energized state), but the spring <NUM> is exerting a force on the armature <NUM>' to dispose the valve seal <NUM> in fluid sealing engagement with the outlet fitting <NUM>' (e.g., to fluidly isolate the second pressurized fluid cavity <NUM> from the cutter body cavity <NUM>').

Activation of actuator assembly <NUM>, namely by applying at least a certain voltage to the coil <NUM> (e.g., disposing the coil <NUM> in an energized state), creates a magnet field that exerts a magnetic force on the armature <NUM>' to move the armature <NUM>' along the longitudinal axis <NUM> from the first/closed position of <FIG> into the second/open position of <FIG> (and against the biasing force of the spring <NUM>), where the valve seal <NUM> (armature <NUM>) is now spaced from the outlet fitting <NUM>'. As such, pressurized fluid (within the first pressurized fluid cavity <NUM>, the first fluid passage <NUM>, the second fluid passage <NUM> and the second pressurized fluid cavity <NUM>) may flow from the second pressurized fluid cavity <NUM>, through the outlet port <NUM> of the outlet fitting <NUM>', and into the cutter body cavity <NUM>' to exert a fluid pressure on the cutter <NUM>' that is directed toward the cable and anvil (not shown in <FIG>, but in accord with <FIG>). Once the pressure within the cutter body cavity <NUM>' satisfies a certain pressure threshold, each latch pin <NUM> should be disabled/sheared/ruptured/broken to allow the cutter <NUM>' to advance in the direction of and to cut/sever the cable (e.g., to separate the hook assembly <NUM> from the remainder of the hoist assembly <NUM> and also from the airframe <NUM> - <FIG>).

<FIG> shows the different sublevel events of the electro-pneumatic (or more generally "fluid") cutting action in a time-based manner for at least the cable cutter assembly <NUM> of <FIG>. Once the electric voltage is applied to the coil <NUM>, the first event is the solenoid valve opening (movement of the armature <NUM> from the <FIG> position to the <FIG> position). The first figure of <FIG> shows the current build up coil <NUM> and the armature/plunger <NUM> movement for valve opening. T<NUM> = the DC voltage application time to the coil <NUM>. T<NUM> = the time at which the coil <NUM> begins to start exerting a pulling force on the armature <NUM> (in a direction that is away from the outlet fitting <NUM>), where the armature <NUM> starts to move, and where the cutter body cavity <NUM> begins getting charged with fluid pressure. Time T<NUM> to T<NUM> defines the electrical time delay of the coil <NUM>. T<NUM> = the time at which solenoid valve opens fully (completion of the movement of the armature <NUM> from the <FIG> position to the <FIG> position). Time T<NUM> to T<NUM> defines the mechanical time delay of the coil <NUM>. Time T<NUM> to T<NUM> (identified as T<NUM> on <FIG>) defines the total time delay or opening response time of the solenoid valve at the specified inlet pressure and the voltage applied.

Once the solenoid valve has opened (where the armature <NUM> has moved from the <FIG> position at least toward the <FIG> position), the pressurized fluid gets discharged to the cutter body cavity <NUM> and the pressure force build-up begins. The second figure of <FIG> shows the fluid pressure build up in the cutter body cavity <NUM>. T<NUM> = the time at which the minimum required fluid pressure force is developed in the cutter body cavity <NUM>, which starts to push and move the cutter/piston <NUM> toward the cable <NUM> and the anvil <NUM>. Time T<NUM> to T<NUM> (identified as T<NUM> on <FIG>) represents the pressurized fluid time delay to reach the actuation pressure within the cutter body cavity <NUM>, where this actuation pressure is sufficient to move the cutter/piston <NUM> toward the cable <NUM> and the anvil <NUM> (e.g., to release the cutter <NUM> by disabling the latch pin(s) <NUM>).

The required magnitude of the above-noted actuation pressure is dependent on the rupturing force of the latch pin(s) <NUM>. A higher actuation pressure (for rupturing the latch pin(s) <NUM>) provides a higher cutting force (for severing the cable <NUM>) and a higher velocity for the cutter/piston <NUM>. That is, the fluid pressure force at which the cutter/piston <NUM> starts to move, along with the associated speed of the cutter/piston <NUM>, is influenced by the latch pin design for its rupturing. The cutting force of the cutter/piston <NUM> is influenced by the actuator design and the latch pin design.

The third figure of <FIG> shows the cutter/piston <NUM> displacement profile with time. Time T<NUM> to T<NUM> (identified as T<NUM> on <FIG>) represents the mechanical time delay for movement of the cutter/piston <NUM>.

T<NUM> = the cutter/piston <NUM> having completed moving to the anvil <NUM> with the required speed and the cutter knife edge <NUM> having hit the cable <NUM>. During this phase, the cutter/piston <NUM> experiences accelerated movement and the cutter knife edge <NUM> of the cutter/piston <NUM> cuts/shears the cable <NUM>. Simultaneously, the pressure force is increasing to induce high energy to the cutter/piston <NUM>. The fourth figure on <FIG> shows the cable cutting physical action time. T<NUM> = the time instant at which cutting of the cable <NUM> is complete. Time T<NUM> to T<NUM> (identified as T<NUM> on <FIG>) represents the time delay for the cutting of the cable <NUM>. Time T<NUM> to T<NUM> (identified as T<NUM> on <FIG>) represents the total time required to cut/sever the cable <NUM> from the time at which the voltage is initially applied to the coil <NUM>.

By suitable design of the solenoid valve, the overall time delay from the instant of voltage application to complete the cable cutting (T<NUM> in <FIG>) may be achieved within <NUM> to <NUM> milliseconds. Compared to a squib-based cable cutter, the actuator assembly <NUM> operates on lower electric current, and the electric power required is much less. By designing for higher DC power, the electric response of the actuator assembly <NUM> can be improved. The actuator assembly <NUM> with dual working airgaps (<FIG>) features fast opening response times. Compared to an electric squib-based cable cutter, the actuator assembly <NUM> may be operated repeatedly, and with at least the potential for reduced maintenance requirements. After each firing, the only expendable typically required is the replacement of the sleeve(s) <NUM> assembled to the leak vent fitting(s) <NUM>. The usage of the above-noted pressure sensor <NUM> facilitates tracking of the fluid pressure (within the first pressurized fluid cavity <NUM>, the first fluid passage <NUM>, the second fluid passage <NUM> and the second pressurized fluid cavity <NUM>) at any time. Using a wireless pressure sensor <NUM> can eliminate associated electric cabling requirements.

Based on the design of at least the cable cutter assembly <NUM> of <FIG>, it is possible to define a minimum threshold pressure within the first pressurized fluid cavity <NUM>, the first fluid passage <NUM>, the second fluid passage <NUM> and the second pressurized fluid cavity <NUM> for the cutting of the cable <NUM> within the minimum required time in the above-noted manner. Due to long service life in the pressurized condition (within the first pressurized fluid cavity <NUM>, the first fluid passage <NUM>, the second fluid passage <NUM> and the second pressurized fluid cavity <NUM>), if the pressure falls below that of the minimum threshold value, the first pressurized fluid cavity <NUM>, the first fluid passage <NUM>, the second fluid passage <NUM> and the second pressurized fluid cavity <NUM> can be "re-pressurized" through the fill valve <NUM>.

An electro-pneumatic design for at least the cable cutter assembly <NUM> may use a fast-acting solenoid valve designed to hold pneumatic pressure with good leak tightness. Upon solenoid energization, pressure is discharged into the cutter body cavity <NUM> where the cutter <NUM> is located. This cavity pressure develops fluid pressure force to accelerate the cutter <NUM> toward the cable <NUM> for cutting/severing the cable <NUM>. The solenoid valve with a stored pressurized fluid (the actuator assembly <NUM>) at least meets the performance of an electric squib-based cable cutter. The actuator assembly <NUM> can be designed for fast response and for the stringent leak tightness. The actuator assembly <NUM> can be used repeatedly and hence this possesses built in test features. Solenoids are highly reliable and cost-effective devices.

The configurations of the cable cutter assemblies <NUM>, <NUM>' can be used for both "new construction" and for retrofits (where the same would replace an electric squib-based cable cutter). For the same amount of gas, usage of higher gas pressure in the first pressurized fluid cavity <NUM>, the first fluid passage <NUM>, the second fluid passage <NUM> and the second pressurized fluid cavity <NUM>, may reduce the volume requirement of one or more of the first pressurized fluid cavity <NUM>, the first fluid passage <NUM>, the second fluid passage <NUM> and the second pressurized fluid cavity <NUM>.

A wireless pressure sensor <NUM> added to the first pressurized fluid cavity <NUM> facilitates tracking of the stored gas pressure data and based on which in-service maintenance may be scheduled. By all these attributes, the cable cutter assemblies <NUM>/<NUM>' possess desired operational reliability features.

Any feature of any other various aspects addressed in this disclosure that is intended to be limited to a "singular" context or the like will be clearly set forth herein by terms such as "only," "single," "limited to," or the like. Merely introducing a feature in accordance with commonly accepted antecedent basis practice does not limit the corresponding feature to the singular. Moreover, any failure to use phrases such as "at least one" also does not limit the corresponding feature to the singular. Use of the phrase "at least substantially," "at least generally," or the like in relation to a particular feature encompasses the corresponding characteristic and insubstantial variations thereof (e.g., indicating that a surface is at least substantially or at least generally flat encompasses the surface actually being flat and insubstantial variations thereof). Finally, a reference of a feature in conjunction with the phrase "in one embodiment" does not limit the use of the feature to a single embodiment.

The foregoing description has been presented for purposes of illustration and description. Furthermore, the description is not intended to limit the invention to the form disclosed herein. Consequently, variations and modifications commensurate with the above teachings, and skill and knowledge of the relevant art, are within the scope of the appended claims. The scope of the disclosure is accordingly to be limited by nothing other than the appended claims.

After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments within the scope of the appended claims.

Claim 1:
A cable cutter assembly for a hoist, comprising:
an actuator assembly (<NUM>), characterized in that it comprises:
at least one pressurized fluid cavity (<NUM>);
a first outlet port (<NUM>);
a solenoid (<NUM>) comprising a coil (<NUM>) and an armature (<NUM>), wherein said armature is movable between a closed position and an open position relative to said first outlet port, wherein said armature engages said first outlet port when in said closed position and is spaced from said first outlet port when and said open position;
a cutter body (<NUM>) comprising a cutter body cavity (<NUM>) fluidly connected with said first outlet port; and
a cutter (<NUM>) disposed within said cutter body cavity;
wherein disposing said armature in said open position fluidly connects said at least one pressurized fluid cavity with said cutter body cavity to move said cutter in a cable cutting direction.