Patent Description:
Bi-stable solenoids typically include a wire coil arranged around a moveable armature. When a current is applied to the wire coil, a magnetic field is generated that can then actuate (i.e., move) the moveable armature from a first position to a second position. In general, an armature within a bi-stable solenoid is moveable between two stable positions. For example, a current may be applied to the wire coil in a first direction with a magnitude sufficient to actuate an armature from a first position to a second position. The armature may remain in the second position until a current is applied to the wire coil in a second direction with a magnitude sufficient to actuate the armature from the second position back to the first position. Again, the armature may remain in the first position until the current is applied to the wire coil in the first direction with a sufficient magnitude.

<CIT> discloses an electromagnet which may operate a small pneumatic valve. The electromagnet is in the form of a pot magnet with a remanent magnet gripped between a root portion the electromagnet core, and pole member having a pole face and shoulders tapering toward the pole face, which are arranged for co-operation with shoulders of a retaining member which may be part of a coil former. The former is held in the pot by a guide ring in an annular top wall of the magnet, which has a raised portion surrounding the hollow armature that is biased away from the core by a spring, and contains one end of an actuating rod guided in the ring. A compression spring is interposed between the end of the rod and a plug in the end of the armature, to enable the armature to start to move downwards before the rod moves.

<CIT> discloses an actuator having an armature plate urged to a stable position by a spring and which may be held in another stable position by a permanent magnet. Application of an appropriate current pulse to a coil within the actuator reduces the flux flow through and the magnetic force on the armature sufficiently to release the armature to the former stable position under the influence of the spring. Two magnetic circuits, one of which includes a non-working air gap, are employed, the non-working air gap serving to maintain a flux path, of a predetermined maximum reluctance, for the permanent magnet when the armature plate is in the former stable position.

<CIT> discloses a controllable coupling assembly and a coupling member for use in the assembly. The member includes a first coupling face oriented to face axially along a rotational axis and has a set of locking formations angularly-spaced about the axis. The member also includes a second coupling face having a reverse pocket which receives a reverse locking element. The pocket defines a first load-bearing surface adapted for abutting engagement with a load-bearing surface of the reverse locking element. The second coupling face is oriented to face radially with respect to the axis. Each of the set of locking formations defines a second load-bearing surface adapted for abutting engagement with a load-bearing surface of a forward locking element.

<CIT> discloses permanent magnet latching solenoid with a central passage carrying a reciprocating armature which has a magnetically permeable bushing press-fit in each end of a bobbin. The outer ends of the bushings define the outer ends of the bore. A separate preformed magnetically permeable frame surrounds the bobbin and includes end wall portions that abut the outer ends of the bushings. The bobbin assembly is inserted laterally into the frame, with the ends of the bushings against the ends of the frame. Openings in the end walls of the frame accommodate free passage of an operator rod element which is affixed to the armature.

<CIT> discloses a bistable solenoid with a permanent magnet arranged between two coil bays. A sleeve is provided around a pin to exert forces of the moving armature on the pin. To this end, a spring is provided between the pin and the sleeve. This enables the pin to move relative to the sleeve and the armature. This ensures that the armature can move between the two stable positions even if an obstacle blocks the motion of the pin.

The present disclosure provides a bi-stable solenoid according to claim <NUM> that includes an internally disposed spring, which allows for the bi-stable solenoid to enter a tooth butt, or intermediate position where a pin can engage a tooth of a gear, and remain biased toward an extended position.

In one aspect, the present invention provides a bi-stable solenoid comprising a housing, a wire coil, a permanent magnet, an armature, a pin, and a spring. The wire coil and the permanent magnet are arranged within the housing. The armature is slidably arranged within the housing and is moveable between a first armature position and a second armature position. The pin at least partially extends out of the housing and is slidably engaged by the armature. The spring is biased between the armature and the pin. When the pin encounters an intermediate position between a retracted position and an extended position due to the pin engaging an obstruction, the spring is configured to maintain a biasing force on the pin until the obstruction is removed. The pin is slidably engaged by the armature such that when the pin is prevented from displacing to the extended position by the obstruction, the armature is allowed to shift from the first armature position to the second armature position.

In an embodiment, a bi-stable solenoid is provided comprising a housing, a wire coil arranged within the housing, a permanent magnet arranged within the housing, and an armature slidably arranged within the housing and moveable between a first armature position and a second armature position. The bi-stable solenoid further includes a pin at least partially extending out of the housing and slidably engaged by the armature. The pin is moveable between an extended position and a retracted position. The bi-stable solenoid further includes a spring that is biased between the armature and the pin. When the armature is moved from the first armature position to the second armature position, the spring applies a force onto a pin, thereby biasing the pin toward the extended position, and when the armature is moved from the first armature position to the second armature position and the pin encounters an obstruction, the spring continues to bias the pin toward the extended position until the obstruction is removed and the pin is allowed to move to the extended position.

The foregoing and other aspects and advantages of the invention will appear from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention, however, and reference is made therefore to the claims and herein for interpreting the scope of the invention.

<FIG> shows a gear system <NUM> according to one aspect of the present disclosure. The gear system <NUM> can include a housing <NUM> enveloping a gear <NUM>, one or more of rocker arms <NUM>, and one or more bi-stable solenoids <NUM>. In the illustrated non-limiting example, the gear system <NUM> includes a pair of rocker arms <NUM> and a corresponding pair of bi-stable solenoids <NUM> configured to actuate the rocker arms <NUM>, as will be described. In some non-limiting examples, the gear system <NUM> may be arranged within a transmission on a vehicle. In other non-limiting examples, the gear system <NUM> may be arranged in an application requiring selective rotational control of a gear.

The gear <NUM> can be rotatably mounted within the housing <NUM>. The pair of rocker arms <NUM> can be rotatably mounted within the housing <NUM>. The rocker arms <NUM> can be configured to engage and disengage the gear <NUM> to selectively prevent or allow rotation of the gear <NUM> in either of the clockwise or counter-clockwise directions.

The pair of bi-stable solenoids <NUM> each include a pin <NUM> configured to interact with a corresponding one of the rocker arms <NUM>. The pins <NUM> are selectively moveable via energization of the corresponding bi-stable solenoid <NUM>. Actuation of the pins <NUM> can correspondingly actuate the rocker arms <NUM> to selectively engage and disengage the gear <NUM>.

Referring now to <FIG>, one of the bi-stables solenoids <NUM> is illustrated. It should be appreciated that the bi-stable solenoids <NUM> can be substantially identical. The bi-stable solenoid <NUM> includes a housing <NUM> at least partially enveloping a first pole piece <NUM>, a bobbin <NUM>, a second pole piece <NUM>, a permanent magnet <NUM>, an armature <NUM>, and a spring <NUM>. In some non-limiting examples, the housing <NUM> can define a generally hollow cylindrical shape and can include a first surface <NUM> and a generally open second end <NUM>. The housing <NUM> can be coupled to a mounting flange <NUM> proximate the open second end <NUM>. The mounting flange <NUM> can at least partially cover the open second end <NUM>, thereby creating an enclosed chamber within the housing <NUM>. The mounting flange <NUM> can be coupled to the housing <NUM>, for example, to fix the bi-stable solenoid <NUM> relative to the gear <NUM>.

The first pole piece <NUM> can be fabricated from a magnetic material (e.g., magnetic steel, iron, nickel, etc.). The first pole piece <NUM> can be disposed at least partially within the housing <NUM> and can extend at least partially through to the first surface <NUM>. The first pole piece <NUM> can include a first armature-receiving portion <NUM> and a first pin-engaging aperture <NUM>. The first armature-receiving portion <NUM> can be disposed at a first end <NUM> of the first pole piece <NUM>, and can include a first armature-receiving recess <NUM> configured to receive the armature <NUM>. The first pin-engaging aperture <NUM> can extend through a second end <NUM> of the first pole piece <NUM>, and can be configured to slidably receive the pin <NUM> therethrough.

The bobbin <NUM> can define a first bobbin portion <NUM> that can be arranged adjacent to the first surface <NUM> of the housing <NUM>. The first bobbin portion <NUM> can define a generally annular shape, and can surround at least a portion of the first pole piece <NUM>. A first coil bay <NUM> of a wire coil <NUM> may be wound around the first bobbin portion <NUM>. The second bobbin portion <NUM> can be arranged adjacent to the mounting flange <NUM> within the housing <NUM>. The second bobbin portion <NUM> can define a generally annular shape, and can surround at least a portion of the second pole piece <NUM>. A second coil bay <NUM> of the wire coil <NUM> may be wound around the second bobbin portion <NUM>.

The second pole piece <NUM> can be fabricated from a magnetic material (e.g., magnetic steel, iron, nickel, etc.). The second pole piece <NUM> can be disposed partially within the housing <NUM> and spaced axially apart from the first pole piece <NUM>. The second pole piece <NUM> can extend at least partially through and be coupled to the mounting flange <NUM>. The second pole piece <NUM> can include a second armature-receiving portion <NUM>, a second pin-engaging aperture <NUM>, and a hollow cylindrical portion <NUM>. The second armature-receiving portion <NUM> can be disposed at a first end <NUM> of the second pole piece <NUM>, and can include a second armature-receiving recess <NUM> configured to receive the armature <NUM>. The second pin-engaging aperture <NUM> can extend through a second end <NUM> of the second pole piece <NUM>, and can be configured to slidably receive the pin <NUM> therethrough. The hollow cylindrical portion <NUM> can extend between the second armature-receiving portion <NUM> and the second end <NUM> of the second pole piece <NUM>.

The permanent magnet <NUM> can define a generally annular shape and is disposed within the housing <NUM> between the second bobbin portion <NUM> and the first bobbin portion <NUM>. The annular shape of the permanent magnet <NUM> enables the armature <NUM> to extend therethrough.

The armature <NUM> can be fabricated from a magnetic material (e.g., magnetic steel, iron, nickel, etc.). The armature <NUM> can include a first portion <NUM>, a second portion <NUM>, and a central aperture <NUM>. During operation, the first portion <NUM> can be configured to engage the first armature-receiving recess <NUM> of the first pole piece <NUM>, and the second portion <NUM> can be configured to engage the second armature-receiving recess <NUM> of the second pole piece <NUM>. The second portion <NUM> of the armature <NUM> can additionally include a spring-receiving recess <NUM> configured to engage the spring <NUM>. The central aperture <NUM> can be configured to slidably receive the pin <NUM> therethrough, as will be described herein.

The pin <NUM> can slidably extend through the first pole piece <NUM>, the armature <NUM>, and the second pole piece <NUM>. The pin <NUM> can slidably engage the second pin-engaging aperture <NUM> of the second pole piece <NUM>, the central aperture <NUM> of the armature <NUM>, and the first pin-engaging aperture <NUM> of the first pole piece <NUM>. The pin <NUM> can include a shoulder <NUM> and a snap ring recess <NUM> arranged on opposing sides of the armature <NUM>. The shoulder <NUM> can extend radially outward from the pin <NUM> and can be sized such that an outer diameter of the shoulder <NUM> is larger than the inner diameter of the central aperture <NUM>. The snap ring recess <NUM> can receive a snap ring <NUM>, which can snap into the snap ring recess <NUM>, thereby fixing the snap ring <NUM> relative to the pin <NUM>. The snap ring <NUM> can be sized such that an outer diameter of the snap ring <NUM> is larger than a diameter of the spring <NUM>. The snap ring recess <NUM> can be axially separated from the shoulder <NUM>, such that the armature <NUM> is arranged between the shoulder <NUM> and the snap ring <NUM>.

In some non-limiting examples, the bi-stable solenoid <NUM> may include a second snap ring <NUM> coupled to the pin <NUM> on an axially opposing side of the armature <NUM> (see, e.g., <FIG>) than the snap ring <NUM>, rather than the shoulder <NUM>. In some non-limiting examples, the bi-stable solenoid <NUM> may include another shoulder arranged on an axially opposing side of the armature <NUM> than shoulder <NUM>, rather than the snap ring <NUM>. In any case, the pin <NUM> is designed to include mechanical structures on axially opposing sides of the armature <NUM> to limit the axial displacement of the pin <NUM> and to provide a structure against which the spring <NUM> may bias the pin <NUM> relative to the armature <NUM>.

The spring <NUM> can envelop a portion of the pin <NUM> between the snap ring <NUM> and the spring receiving recess <NUM> of the armature <NUM>. The spring <NUM> can be biased between the spring receiving recess <NUM> and the first snap ring <NUM>. When assembled, the spring <NUM> may bias the pin <NUM> in an axial direction away from the armature <NUM> (i.e., in an downward direction from the perspective of <FIG>).

One non-limiting example of the operation of the bi-stable solenoid <NUM> within the gear system <NUM> will be described below with reference to <FIG>. It should be appreciated that the described operation of the bi-stable solenoid <NUM> can be adapted to any system that includes a suitable gear. In operation, the wire coil <NUM> of the bi-stable solenoid <NUM> may be selectively energized, i.e., supplied with a current in a desired direction at a predetermined magnitude. In response to the current being applied to the wire coil <NUM>, the armature <NUM> can move between two stable positions depending on the direction of the current applied to the wire coil <NUM>. In the illustrated non-limiting example, the armature <NUM> may be moveable between a first armature position (see, e.g., <FIG>) where the armature <NUM> contacts the first armature-receiving recess <NUM> of the first pole piece <NUM> and a second armature position (see, e.g., <FIG>) where the armature <NUM> contacts the second armature-receiving recess <NUM> of the second pole piece <NUM>.

In some non-limiting examples, the armature <NUM> may be in the first armature position and the wire coil <NUM> of the bi-stable solenoid <NUM> may be energized with a current in a first direction. The armature <NUM> may then fully shift (i.e., actuate) to the second armature position and the wire coil <NUM> may be de-energized (i.e., the current is removed). The armature <NUM> will remain in the second armature position until the wire coil <NUM> is energized with a current in a second direction opposite to the first direction. The armature <NUM> may then fully shift back to the first armature position and the wire coil <NUM> may be de-energized. In this way, the operation of the bi-stable solenoid <NUM> may require a reduced energy input because the wire coil <NUM> is not required to be continuously energized.

Due to the interactions between the shoulder <NUM>, the armature <NUM>, the spring <NUM>, and the snap ring <NUM>, the movement of the armature <NUM> may influence a position of the pin <NUM>. For example, during operation, the pin <NUM> may be moved between a retracted position (see, e.g., <FIG>) and an extended position (see, e.g., <FIG>), in response to movement of the armature <NUM> between the first armature position and the second armature position. In some instances, the pin <NUM> may encounter an intermediate position (see, e.g., <FIG>) where the pin <NUM> is temporarily prevented from fully extending from the retracted position to the extended position due to an obstruction. As will be described, the design and properties of the bi-stable solenoid <NUM> enable the pin <NUM> to encounter the intermediate position and eventually reach the desired extended position without requiring energization of the wire coil <NUM>.

In some non-limiting examples, movement of the pin <NUM> between the extended position and the retracted position may inhibit or allow the gear <NUM> to rotate in a desired direction. As shown in <FIG> and <FIG>, if it is desired to prevent rotation of the gear <NUM> in a desired direction, current can be selectively applied to the wire coil <NUM> to move the pin <NUM> into the extended position (see, e.g., <FIG>). To move the pin <NUM> into the extended position from the retracted position, a current in the first direction may be applied to the wire coil <NUM> to shift the armature <NUM> to the second armature position. As the armature <NUM> moves from the first armature position to the second armature position, the spring <NUM> may be compressed and force the snap ring <NUM>, and thereby the pin <NUM>, to displace in a first axial direction <NUM> (e.g., downward from the perspective of <FIG> and <FIG>). The pin <NUM> can be allowed to displace in the first axial direction <NUM> until the shoulder <NUM> engages the armature <NUM>.

As the pin <NUM> is displaced to the extended position, an actuation end <NUM> of the pin <NUM> engages the rocker arm <NUM> and displaces the rocker arm <NUM> into engagement with a portion of the gear <NUM>. If the rocker arm <NUM> does not contact one of the gear teeth <NUM> as the pin <NUM> displaces to the extended position, the rocker arm <NUM> is displaced into contact with the gear <NUM> in a space between adjacent gear teeth <NUM>. In this illustrated position of <FIG>, the rocker arm <NUM> is configured to prevent the gear <NUM> from rotating in a given direction. For example, in the illustrated non-limiting example of <FIG>, the gear <NUM> is prevented from rotating in a counter-clockwise direction.

In the illustrated non-limiting example of <FIG>, the rocker arms <NUM> can be arranged such that one rocker arm <NUM> selectively prevents rotation of the gear <NUM> in the clockwise direction (e.g., the rocker arm <NUM> on the right) and the other rocker arm <NUM> prevents rotation of the gear <NUM> in the counter-clockwise direction (e.g., the rocker arm <NUM> on the left). As such, if both rocker arms <NUM> are actuated into the locked position, the gear <NUM> can be prevented rotation in both the clockwise and counter clockwise directions simultaneously.

With continued reference to <FIG> and <FIG>, if it is desired to permit rotation of the gear <NUM> in a desired direction, current can be selectively applied to the wire coil <NUM> to move the pin <NUM> into the retracted position (see, e.g., <FIG>). To move the pin <NUM> into the retracted position from the extended position, a current in the second direction may be applied to the wire coil <NUM> to shift the armature <NUM> to the first armature position. As the armature <NUM> moves from the second armature position to the first armature position, the armature <NUM> may displace the pin <NUM> therewith due to the engagement between the armature <NUM> and the shoulder <NUM>. That is, the pin <NUM> can be displaced in a second axial direction <NUM> (e.g., upward from the perspective of <FIG>) until the armature <NUM> reaches the second armature position.

As the pin <NUM> is displaced to the retracted position, the actuation end <NUM> of the pin <NUM> can be displaced away from the gear <NUM>, which allows a rocker arm spring <NUM> to bias the rocker arm <NUM> out of engagement with the gear <NUM> and permits the gear <NUM> to rotate.

Turning to <FIG>, in some instances during operation, as the pin <NUM> is displaced from the retracted position to the extended position, the rocker arm <NUM> can engage a gear tooth <NUM> rather than fully extend into the space between adjacent gear teeth <NUM>. When the rocker arm <NUM> engages a gear tooth <NUM>, the pin <NUM> can be in an intermediate position, as illustrated in <FIG>. In the intermediate position, the pin <NUM> is inhibited from fully displacing to the extended position; however, the design of the bi-stable solenoid and, specifically, the use of the spring <NUM> allow the armature <NUM> to fully shift to the second armature position even through the pin <NUM> is prevented from fully displacing to the extended position. Since the armature <NUM> displaces to the second armature position, the spring <NUM> is compressed applies a biasing force on the snap ring <NUM> and thereby onto the pin <NUM>. As such, in the intermediate position, the spring <NUM> provides a biasing force on the pin <NUM> until the gear <NUM> rotates and the rocker arm <NUM> is allowed to displace into the space between adjacent gear teeth <NUM>, which allows the pin <NUM> to displace to the extended position.

The use of the spring <NUM> within the bi-stable solenoid <NUM> allows the pin <NUM> to encounter the intermediate position and ensure that the pin <NUM> inevitably reaches the extended position, without requiring the wire coil <NUM> to be energized. This functionality can allow the armature <NUM> to reach the second armature position even when the pin <NUM> encounters the intermediate position, which maintains the bi-stable functionality of the solenoid <NUM> and reduces the power consumption.

Within this specification embodiments have been described in a way which enables a clear and concise specification to be written, but it is intended and will be appreciated that embodiments may be variously combined or separated without parting from the invention. For example, it will be appreciated that all preferred features described herein are applicable to all aspects of the invention described herein.

Thus, while the invention has been described in connection with particular embodiments and examples, the invention is only limited by the claims attached hereto.

Claim 1:
A bi-stable solenoid (<NUM>) comprising:
a housing (<NUM>);
a wire coil (<NUM>) including a first coil bay (<NUM>) and a second coil bay (<NUM>) arranged within the housing (<NUM>);
a permanent magnet (<NUM>) arranged within the housing (<NUM>);
an armature (<NUM>) slidably arranged within the housing (<NUM>) and moveable between a first armature position and a second armature position;
a pin (<NUM>) at least partially extending out of the housing (<NUM>) and slidably engaged by the armature (<NUM>); and
a spring (<NUM>) biased between the armature (<NUM>) and the pin (<NUM>),
wherein the pin (<NUM>) is adapted to encounter an intermediate position between a retracted position and an extended position upon engaging an obstruction, the spring (<NUM>) is configured to maintain a biasing force on the pin (<NUM>) until the obstruction is removed, and
wherein the pin (<NUM>) is slidably engaged by the armature (<NUM>) such that when the pin (<NUM>) is prevented from displacing to the extended position by the obstruction, the armature (<NUM>) is allowed to shift from the first armature position to the second armature position.