Magnetic system for controlling the operating mode of an overrunning coupling assembly and overrunning coupling and magnetic control assembly having same

A magnetic system for controlling the operating mode of an overrunning coupling assembly is provided. The system includes a ferromagnetic or magnetic element received within a pocket in an uncoupling position and is movable outwardly from the pocket to a coupling position. The element controls the operating mode of the coupling assembly. An armature is connected to the element to move the element between the coupling and uncoupling positions. A magnetic field sensor is disposed adjacent and stationary with respect to the element for sensing magnetic flux to produce an output signal which is based on the position of the element. A variable magnetic field is generated in response to movement of the element between the coupling and uncoupling positions.

OVERVIEW

Coupling assemblies such as clutches are used in a wide variety of applications to selectively couple power from a first rotatable driving member, such as a driving disk or plate, to a second, independently rotatable driven member, such as a driven disk or plate. In one known variety of clutches, commonly referred to as “one-way” or “overrunning” clutches, the clutch engages to mechanically couple the driving member to the driven member only when the driving member rotates in a first direction relative to the driven member. Once so engaged, the clutch will release or decouple the driven member from the driving member only when the driving member rotates in a second, opposite direction relative to the driven member. Further, the clutch otherwise permits the driving member to freely rotate in the second direction relative to the driven member. Such “freewheeling” of the driving member in the second direction relative to the driven member is also known as the “overrunning” condition.

One type of one-way clutch includes coaxial driving and driven plates having generally planar clutch faces in closely spaced, juxtaposed relationship. A plurality of recesses or pockets is formed in the face of the driving plate at angularly spaced locations about the axis, and a strut or pawl is disposed in each of the pockets. Multiple recesses or notches are formed in the face of the driven plate and are engageable with one or more of the struts when the driving plate is rotating in a first direction. When the driving plate rotates in a second direction opposite the first direction, the struts disengage the notches, thereby allowing freewheeling motion of the driving plate with respect to the driven plate.

When the driving plate reverses direction from the second direction to the first direction, the driving plate typically rotates relative to the driven plate until the clutch engages. As the amount of relative rotation increases, the potential for an engagement noise also increases.

Controllable or selectable one-way clutches (i.e., OWCs) are a departure from traditional one-way clutch designs. Selectable OWCs add a second set of locking members in combination with a slide plate. The additional set of locking members plus the slide plate adds multiple functions to the OWC. Depending on the needs of the design, controllable OWCs are capable of producing a mechanical connection between rotating or stationary shafts in one or both directions. Also, depending on the design, OWCs are capable of overrunning in one or both directions. A controllable OWC contains an externally controlled selection or control mechanism. Movement of this selection mechanism can be between two or more positions which correspond to different operating modes.

A properly designed controllable OWC can have near-zero parasitic losses in the “off” state. It can also be activated by electro-mechanics and does not have either the complexity or parasitic losses of a hydraulic pump and valves.

In a powershift transmission, tip-in clunk is one of most difficult challenges due to absence of a torque converter. When the driver tips-in, i.e., depresses the accelerator pedal following a coast condition, gear shift harshness and noise, called clunk, are heard and felt in the passenger compartment due to the mechanical linkage, without a fluid coupling, between the engine and powershift transmission input. Tip-in clunk is especially acute in a parking-lot maneuver, in which a vehicle coasting at low speed is then accelerated in order to maneuver into a parking space.

In order to achieve good shift quality and to eliminate tip-in clunk, a powershift transmission should employ a control strategy that is different from that of a conventional automatic transmission. The control system should address the unique operating characteristics of a powershift transmission and include remedial steps to avoid the objectionable harshness yet not interfere with driver expectations and performance requirements of the powershift transmission. There is a need to eliminate shift harshness and noise associated with tip-in clunk in a powershift transmission.

For purposes of this disclosure, the term “coupling” should be interpreted to include clutches or brakes wherein one of the plates is drivably connected to a torque delivery element of a transmission and the other plate is drivably connected to another torque delivery element or is anchored and held stationary with respect to a transmission housing. The terms “coupling”, “clutch” and “brake” may be used interchangeably.

A pocket plate may be provided with angularly disposed recesses or pockets about the axis of the one-way clutch. The pockets are formed in the planar surface of the pocket plate. Each pocket receives a torque transmitting strut, one end of which engages an anchor point in a pocket of the pocket plate. An opposite edge of the strut, which may hereafter be referred to as an active edge, is movable from a position within the pocket to a position in which the active edge extends outwardly from the planar surface of the pocket plate. The struts may be biased away from the pocket plate by individual springs.

A notch plate may be formed with a plurality of recesses or notches located approximately on the radius of the pockets of the pocket plate. The notches are formed in the planar surface of the notch plate.

Another example of an overrunning planar clutch is disclosed in U.S. Pat. No. 5,597,057.

U.S. Pat. No. 6,854,577 discloses a sound-dampened, one-way clutch including a plastic/steel pair of struts to dampen engagement clunk. The plastic strut is slightly longer than the steel strut. This pattern can be doubled to dual engaging. This approach has had some success. However, the dampening function stopped when the plastic parts became exposed to hot oil over a period of time.

Metal injection molding (MIM) is a metalworking process where finely-powdered metal is mixed with a measured amount of binder material to comprise a ‘feedstock’ capable of being handled by plastic processing equipment through a process known as injection mold forming. The molding process allows complex parts to be shaped in a single operation and in high volume. End products are commonly component items used in various industries and applications. The nature of MIM feedstock flow is defined by a science called rheology. Current equipment capability requires processing to stay limited to products that can be molded using typical volumes of 100 grams or less per “shot” into the mold. Rheology does allow this “shot” to be distributed into multiple cavities, thus becoming cost-effective for small, intricate, high-volume products which would otherwise be quite expensive to produce by alternate or classic methods. The variety of metals capable of implementation within MIM feedstock are referred to as powder metallurgy, and these contain the same alloying constituents found in industry standards for common and exotic metal applications. Subsequent conditioning operations are performed on the molded shape, where the binder material is removed and the metal particles are coalesced into the desired state for the metal alloy.

As used herein, the term “sensor” is used to describe a circuit or assembly that includes a sensing element and other components. In particular, as used herein, the term “magnetic field sensor” is used to describe a circuit or assembly that includes a magnetic field sensing element and electronics coupled to the magnetic field sensing element.

As used herein, the term “magnetic field sensing element” is used to describe a variety of electronic elements that can sense a magnetic field. The magnetic field sensing elements can be, but are not limited to, Hall effect elements, magnetoresistance elements, or magnetotransistors. As is known, there are different types of Hall effect elements, for example, a planar Hall element, a vertical Hall element, and a circular vertical Hall (CVH) element. As is also known, there are different types of magnetoresistance elements, for example, a giant magnetoresistance (GMC) element, an anisotropic magnetoresistance element (AMR), a tunneling magnetoresistance (TMR) element, an Indium antimonide (InSb) sensor, and a magnetic tunnel junction (MTJ).

As is known, some of the above-described magnetic field sensing elements tend to have an axis of maximum sensitivity parallel to a substrate that supports the magnetic field sensing element, and others of the above-described magnetic field sensing elements tend to have an axis of maximum sensitivity perpendicular to a substrate that supports the magnetic field sensing element. In particular, planar Hall elements tend to have axes of sensitivity perpendicular to a substrate, while magnetoresistance elements and vertical Hall elements (including circular vertical Hall (CVH) sensing element) tend to have axes of sensitivity parallel to a substrate.

Magnetic field sensors are used in a variety of applications, including, but not limited to, an angle sensor that senses an angle of a direction of a magnetic field, a current sensor that senses a magnetic field generated by a current carried by a current-carrying conductor, a magnetic switch that senses the proximity of a ferromagnetic object, a rotation detector that senses passing ferromagnetic articles, for example, magnetic domains of a ring magnet, and a magnetic field sensor that senses a magnetic field density of a magnetic field.

Modern automotive vehicles employ an engine transmission system having gears of different sizes to transfer power produced by the vehicle's engine to the vehicle's wheels based on the speed at which the vehicle is traveling. The engine transmission system typically includes a clutch mechanism which may engage and disengage these gears. The clutch mechanism may be operated manually by the vehicle's driver, or automatically by the vehicle itself based on the speed at which the driver wishes to operate the vehicle.

In automatic transmission vehicles, a need arises for the vehicle to sense the position of the clutch for smooth, effective shifts between gears in the transmission and for overall effective transmission control. Therefore, a clutch-position sensing component for sensing the linear position of the clutch may be used by automatic transmission vehicles to facilitate gear shifting and transmission control.

Current clutch-position sensing components utilize magnetic sensors. One advantage to using magnetic sensors is that the sensor need not be in physical contact with the object being sensed, thereby avoiding mechanical wear between the sensor and the object. However, actual linear clutch measurement accuracy may be compromised when the sensor is not in physical contact with the sensed object because of a necessary gap or tolerance that exists between the sensor and the object. Moreover, current sensing systems addressing this problem use coils and certain application-specific integrated circuits which are relatively expensive.

U.S. Pat. No. 8,324,890 discloses a transmission clutch position sensor which includes two Hall sensors located at opposite ends of a flux concentrator outside the casing of the transmission to sense a magnetic field generated by a magnet attached to the clutch piston. To reduce sensitivity to magnet-to-sensor gap tolerances, a ratio of the voltage of one Hall sensor to the sum of the voltages from both Hall sensors is used to correlate to the piston and, hence, clutch position.

SUMMARY OF EXAMPLE EMBODIMENTS

An object of at least one embodiment of the present invention is to provide a magnetic control system for controlling the operating mode of an overrunning coupling assembly and an overrunning coupling and magnetic control assembly having such a system.

In carrying out the above object and other objects of at least one embodiment of the present invention, a magnetic system for controlling the operating mode of an overrunning coupling assembly is provided. The assembly includes a coupling member having a first coupling face and a coupling subassembly having a second coupling face with a pocket defining a load-bearing shoulder. The coupling faces are in close-spaced opposition with one another. At least one of the coupling member and the coupling subassembly is mounted for rotation about a rotary axis. The system includes a ferromagnetic or magnetic element received within the pocket in an uncoupling position and movable outwardly from the pocket to a coupling position characterized by abutting engagement of the element with the load-bearing shoulder. The element controls the operating mode of the coupling assembly. An electromagnetic source includes at least one excitation coil. A reciprocating armature is arranged concentrically relative to the at least one excitation coil and is axially movable when the at least one excitation coil is supplied with current. The armature is connected to the element to move the element between the coupling and uncoupling positions. A magnetic field sensor is disposed adjacent and stationary with respect to the element for sensing magnetic flux to produce an output signal which is based on the position of the element. A variable magnetic field is generated in response to movement of the element between the coupling and uncoupling positions.

The sensor may include a magnetic field sensing element.

The sensor may be back-biased wherein the element is a ferromagnetic element.

The element may be a locking element which controls the operating mode of the coupling assembly.

The locking element may be an injection molded strut.

The system may further include a return biasing member to urge the armature to a return position which corresponds to the uncoupling position of the element.

The coupling faces may be oriented to face axially.

The pocket may have a T-shape.

The element may include at least one projecting leg portion which provides an attachment location for a leading end of the armature.

Each leg portion may have an aperture, wherein the system may further include a pivot pin received within each aperture to allow rotational movement of the element in response to reciprocating movement of the armature and wherein the leading end of the armature may be connected to the element via the pivot pin.

Each aperture may be an oblong aperture to receive the pivot pin to allow both rotation and translational movement of the element in response to reciprocating movement of the armature.

The coupling assembly may be a clutch assembly and the coupling faces may be clutch faces.

Further in carrying out the above object and other objects of at least one embodiment of the present invention, an overrunning coupling and magnetic control assembly is provided. The assembly includes a coupling member having a first coupling face and a coupling subassembly having a second coupling face with a pocket defining a load-bearing shoulder. The coupling faces are in close-spaced opposition with one another. At least one of the coupling member and the coupling subassembly is mounted for rotation about a rotary axis. A ferromagnetic or magnetic element is received within the pocket in an uncoupling position and is movable outwardly from the pocket to a coupling position characterized by abutting engagement of the element with the load-bearing shoulder. The element controls the operating mode of the coupling assembly. An electromagnetic source includes at least one excitation coil. A reciprocating armature is arranged concentrically relative to the at least one excitation coil and is axially movable when the at least one excitation coil is supplied with current. The armature is connected to the element to move the element between the coupling and uncoupling positions. A magnetic field sensor is disposed adjacent and stationary with respect to the element for sensing magnetic flux to produce an output signal which is based on the position of the element. A variable magnetic field is generated in response to movement of the element between the coupling and uncoupling positions.

The sensor may include a magnetic field sensing element.

The sensor may be back-biased wherein the element is a ferromagnetic element.

The element may be a locking element such as an injection molded strut.

The assembly may further include a return biasing member to urge the armature to a return position which corresponds to the uncoupling position of the element.

The coupling faces may be oriented to face axially.

The pocket may have a T-shape.

The element may include at least one projecting leg portion which provides an attachment location for a leading end of the armature.

Each leg portion may have an aperture. The assembly may further include a pivot pin received within each aperture to allow rotational movement of the element in response to reciprocating movement of the armature. The leading end of the armature may be connected to the element via the pivot pin.

Each aperture may be an oblong aperture to receive the pivot pin to allow both rotation and translational movement of the element in response to reciprocating movement of the armature.

The coupling member may be a clutch member and the coupling faces may be clutch faces.

DETAILED DESCRIPTION

Referring now toFIG. 3, there is illustrated a planar, controllable coupling assembly, generally indicated at11. The assembly11includes a first coupling member, generally indicated at10, a notch plate or member, generally indicated at12, and an electromechanical apparatus, generally indicated at15. The coupling assembly11may be a ratcheting, one-way clutch assembly. The second member12includes a second coupling face16in closed-spaced opposition with an outer coupling face14of a housing part13of the apparatus15when the members10and12are assembled and held together by a locking or snap ring18. At least one of the members10and12is mounted for rotation about a common rotational axis.

The outer coupling face14of the housing part13has a single, T-shaped recess or pocket22, as best shown inFIG. 2. The recess22defines a load-bearing first shoulder24. The second coupling face16of the notch plate12has a plurality of recesses or notches (not shown but well known in the art). Each notch of the notches defines a load-bearing second shoulder.

Referring toFIGS. 1-3, the electromechanical apparatus15may include a locking strut or element, generally included at26, disposed between the coupling faces14and16of the housing part13and the member12, respectively, when the members10and12are assembled and held together.

The element26may comprise a ferromagnetic locking element or strut movable between first and second positions. The first position (phantom lines inFIG. 3) is characterized by abutting engagement of the locking element26with a load-bearing shoulder (not shown) of the member12and the shoulder24of the pocket22formed in an end wall28of the housing part13. The second position (solid lines inFIG. 3) is characterized by non-abutting engagement of the locking element26with a load-bearing shoulder of at least one of the member12and the end wall28.

The electromechanical apparatus15includes the housing part13which has a closed axial end including the end wall28. The end wall28has the outer coupling face14with the single pocket22which defines the load-bearing shoulder24which is in communication with an inner face29of the end wall28. The housing part13may be a metal (such as aluminum) injection molded (MIM) part.

The apparatus15also includes an electromagnetic source, generally indicated at31, including at least one excitation coil33which is at least partially surrounded by a skirt of the housing part13.

The element or strut26is shown as being received within the pocket22in its refracted, uncoupling position inFIG. 3. The strut26is movable outwardly from the pocket22to an extended, coupling position (phantom lines inFIG. 3) characterized by abutting engagement of the strut26with a load-bearing shoulder of the notch plate12and the shoulder24.

The apparatus15also includes a reciprocating armature, generally indicated at35, arranged concentrically relative to the at least one excitation coil33and is axially movable when the at least one excitation coil33is supplied with current. The coil33is wound about a tube45between plates43and47. The plate43abuts against the surface29. The armature35extends through a hole46formed through the plate43and is connected at its leading end37to the element26to move the element26between its coupling and uncoupling positions. The armature35also extends through an aperture38formed through the tube45. The opposite end36of the armature35has a locking ring30(FIG. 1) which limits movement of the armature35in the aperture38towards the plate12by abutting against the lower surface of the tube45but allows the armature35to extend below the lower surface of the tube45.

The element26is pivotally connected to the leading end37of the armature35wherein the armature35pivotally moves the element26within the pocket22in response to reciprocating movement of the armature35.

The apparatus15also preferably includes a return spring41, which extends between the plate43and a shoulder in the outer surface of the tube45, to return the armature35and the tube45to their home position when the coil33is de-energized, thereby returning the element26to its uncoupling position. The apparatus also includes a spring34which urges the armature35to move the element26towards its coupling position. In other words, the biasing member, the spring41, urges the armature35via the tube45to a return position which corresponds to its uncoupling position of the element26while the biasing member or spring34urges the armature35and connected element26to its coupled position and opposes any force in the opposite direction.

The housing part13and/or the plate47preferably has holes to allow oil to circulate within the housing part13. Preferably, the at least one coil33, the housing part13, the tube45and the armature35comprise a low profile solenoid. The locking element26may be a metal (such as aluminum) injection molded (i.e. MIM) strut.

The housing part13has at least one apertured attachment flange49to attach the apparatus15to the coupling member10(corresponding aperture not shown) of the coupling assembly11.

The element26includes at least one and, preferably, two projecting leg portions51which provide an attachment location for the leading end37of the armature35. Each leg portion51has an aperture53. The apparatus15further comprises a pivot pin55received within each aperture53to allow rotational movement of the element26in response to reciprocating movement of the armature35wherein the leading end37of the armature35is connected to the element26via the pivot pin55.

Preferably, each aperture53is an oblong aperture which receives the pivot pin55to allow both rotation and translational movement of the element26in response to reciprocating movement of the armature35. Each locking strut26may comprise any suitable rigid material such as ferrous metal, (i.e. steel).

FIGS. 1,2and3show a magnetic field sensor or device, generally indicated at100. The device100may be a Hall-effect sensor which senses position of the strut26. The strut26may carry or support a rare-earth, automotive grade, magnet or pellet (not shown) which may be embedded in a hole formed in the outer surface of the strut26. In that case, the strut26is a non-ferrous strut such as an aluminum strut. Alternatively, and preferably, the strut26is a ferromagnetic strut.

The device100typically has three wires108(input, output and ground) and provides an industry standard, push-pull voltage output based on position of the strut26in the pocket22. The device100accurately detects the position of the strut26with a single output (i.e., voltage output). The device100is preferably mounted adjacent to and below the pocket22and the wires108extend through an aperture109formed in the plate43and through an aperture110formed through the side wall or skirt of the housing part13. The wires108are coupled to a solenoid controller (FIG. 3) which, in turn, is coupled to a main controller and to a coil drive circuit which supplies drive signals to the coil33in response to control signals from the solenoid controller. The device100may be held in place by fasteners or by an adhesive so that an upper surface of the device100is in close proximity to the bottom surface of the strut26in the uncoupling position of the strut26.

The sensor100is typically back-biased when the strut26is ferromagnetic and typically includes a Hall sensor or sensing element mounted on a circuit board114on which other electronics or components are mounted, as is well-known in the art. The sensor100is preferably back-biased in that it includes a rare-earth magnet112which creates a magnetic flux or field which varies as the strut26moves. The sensor100may comprise a back-biased, Hall Effect device available from Allegro Microsystems.

In other words, the device100is preferably a back-biased device wherein the device includes a rare earth pellet or magnet whose magnetic field varies as the strut26moves towards and away from its uncoupled position. The variable magnetic field is sensed by the magnetic sensing element of the device100.

The output signal from the device100is a feedback signal which is received by the solenoid controller which, in turn, provides a control signal to the circuit which, in turn, provides drive control signals to control current flow to the coil73. By providing feedback, the resulting closed-loop control system has improved sensitivity, accuracy and repeatability.

The electromechanical apparatus15of the exemplary clutch assembly11may be carried by a driving member of the clutch assembly11or a driven member of the assembly11. Moreover, the strut26of the exemplary clutches assemblies may have any suitable configuration depending on whether the assembly is a planar coupling assembly as shown herein or a rocker coupling assembly (not shown). Also, each strut or rocker (in a radial coupling assembly) may have a middle portion that is thicker than each end portion of the strut or rocker.