Rotational coupling device for bimodal selective output

A rotational coupling device drives an output synchronous with either of two inputs. The device includes a hub disposed about an axis and an output member supported on the hub for rotation about the axis. First and second input members disposed about the hub are configured to rotate in first and second rotational directions and at first and second speeds, respectively, with at least one of the directions and speeds differing. A clutch member is disposed axially between the input members and coupled to the output member. An electromagnet is on an opposite side of the second input member relative to the clutch member. When the electromagnet is deenergized, the clutch member engages the first input member and the output member rotates with the first input member. When the electromagnet is energized, the clutch member engages the second input member and the output member rotates with the second input member.

BACKGROUND OF THE INVENTION

a. Field of the Invention

This disclosure relates to a rotational coupling device. In particular, the disclosure relates to a rotational coupling device that enables transfer of torque to an output member from either of two input members to drive the output member in different rotational directions and/or at different speeds.

b. Background Art

Rotational coupling devices such as clutches and brakes are used to control transfer of torque between rotational bodies. One conventional application for a rotational coupling device is the transfer of a driving torque to a fan used in cooling a vehicle or another apparatus. For example, puller fans are often used to pull cooler air through a vehicle's radiator to assist in cooling components of the vehicle. By reversing the direction of rotation of the fan, the same fan can also be used to expel heat from the vehicle and/or to expel contaminants (e.g., plant debris) from the vehicle's radiator. Conventional rotational coupling devices used with cooling fans are only capable of transferring rotational torque to drive the fan in one rotational direction. Reversing the direction of the fan therefore requires a separate structure such as a motor. Another conventional application for a rotational coupling device is to transfer a driving torque from a vehicle engine to an alternator or other vehicle accessory. It is desirable, however, to be able to drive the alternator or other accessories at different speeds (e.g., at a higher speed when the vehicle is idling and at a lower speed when the vehicle is in motion) and many conventional rotational coupling devices are only capable of driving the alternator or accessory at one speed.

The inventors herein have recognized a need for a rotational coupling device that will minimize and/or eliminate one or more of the above-identified deficiencies.

BRIEF SUMMARY OF THE INVENTION

This disclosure relates to a rotational coupling device. In particular, the disclosure relates to a rotational coupling device that enables transfer of torque to an output member from either of two input members to drive the output member in different rotational directions and/or at different speeds.

A rotational coupling device in accordance with one embodiment of the invention includes a hub disposed about an axis and an output member supported on the hub for rotation relative to the hub about the axis. The device further includes a first input member disposed about the hub and configured to rotate relative to the hub in a first rotational direction and at a first speed. The device further includes a second input member disposed about the hub and configured to rotate relative to the hub in a second rotational direction and at a second speed. At least one of the second rotational direction and the second speed is different from a corresponding one of the first rotational direction and the first speed. The device further includes a clutch member disposed axially between the first and second input members and coupled to the output member. The device further includes an electromagnet disposed on an opposite side of the second input member relative to the clutch member. In the absence of energizing the electromagnet, the clutch member engages the first input member so that the output member rotates with the first input member. Energizing the electromagnet causes the clutch member to engage the second input member so that the output member rotates with the second input member.

A rotational coupling device in accordance with another embodiment of the invention includes a hub disposed about an axis and an output member supported on the hub for rotation relative to the hub about the axis. The device further includes a first input member disposed about the hub and configured to rotate relative to the hub in a first rotational direction and at a first speed. The device further includes a second input member disposed about the hub and configured to rotate relative to the hub in a second rotational direction and at a second speed. At least one of the second rotational direction and the second speed is different from a corresponding one of the first rotational direction and the first speed. The device further includes a clutch member disposed axially between the first and second input members. The clutch member is coupled to the output member for rotation therewith, but axially movable relative to the output member. The device further includes a spring biasing the clutch member towards the first input member. The device further includes an electromagnet disposed on an opposite side of the second input member relative to the clutch member. In the absence of energizing the electromagnet, the clutch member engages the first input member so that the output member rotates with the first input member. Energizing the electromagnet causes the clutch member to engage the second input member so that the output member rotates with the second input member.

A rotational coupling device in accordance with another embodiment of the invention includes a hub disposed about an axis, a first bearing disposed about the hub and an output member supported on the first bearing for rotation relative to the hub about the axis. The device further includes a second bearing disposed about the output member and a first input member disposed about the hub and supported on the second bearing. The first input member is configured to rotate relative to the hub in a first rotational direction and at a first speed. The device further includes a third bearing disposed about the hub and a second input member disposed about the hub and supported on the third bearing. The second input member is configured to rotate relative to the hub in a second rotational direction and at a second speed. At least one of the second rotational direction and the second speed is different from a corresponding one of the first rotational direction and the first speed. The device further includes a clutch member disposed axially between the first and second input members and coupled to the output member. The device further includes an electromagnet disposed on an opposite side of the second input member relative to the clutch member. In the absence of energizing the electromagnet, the clutch member engages the first input member so that the output member rotates with the first input member. Energizing the electromagnet causes the clutch member to engage the second input member so that the output member rotates with the second input member.

A rotational coupling device in accordance with the present disclosure is advantageous relative to conventional coupling devices. In particular, the disclosed coupling device enables transfer of torque from either of two input members to the output member so that the output member may be driven in different rotational directions and/or at different speeds. When used to drive a cooling fan, for example, the device can result in rotation of the fan in either direction to cool vehicle components and to expel heat or contaminants from the vehicle without the use of an additional motor or similar structure. When used to drive an alternator or other vehicle accessory, for example, the device can drive the alternator or accessory at different speeds during vehicle idling and motion.

The foregoing and other aspects, features, details, utilities, and advantages of the invention will be apparent from reading the following detailed description and claims, and from reviewing the accompanying drawings illustrating features of this invention by way of example.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the drawings wherein like reference numerals are used to identify identical components in the various views,FIG. 1illustrates a rotational coupling device10in accordance with one embodiment of the invention. Device10functions as a clutch to selectively transfer torque from an engine, electric motor or other conventional power source. Device10also functions as a brake when torque is not being transferred. Device10may be provided for use in a vehicle. In one embodiment, device10is provided for use in a skid steer loader and, in particular, to control rotation of a cooling fan in the skid steer loader. In another embodiment, device10is provided to drive a vehicle alternator or another vehicle accessory at different speeds (e.g., during vehicle idling and motion). It will be understood by those of ordinary skill in the art, however, that device10may be used in a wide variety of applications requiring a clutch and/or brake. Device10may include a hub12, an output member14, bearings16,18,20, input members22,24, a clutch member26, means, such as one or more pins28for coupling clutch member26to output member14, means, such as one or more springs30for biasing clutch member26in one direction, and means, such as electromagnet32, for urging clutch member26in the opposite direction. Device10may be provided as a assembled product for use in various applications.

Hub12provides structural support for and orients the other components of device10. Hub12may be made from conventional metals and metal alloys. Hub12may be disposed about, and centered about, an axis34that serves as a rotational axis for various components of device10. In the illustrated embodiment, hub12includes two members36,38that are generally circular in cross section with member38disposed about member36intermediate the axial ends of member36. It should be understood, however, that hub12may alternatively comprise a unitary structure. Member36may define an axially extending through bore40configured to receive a fastener42such as a bolt through which hub12may be secured to a stationary structure and fixed against rotation. In accordance with one aspect of the disclosed embodiment, final assembly of device10may be accomplished using a single fastener42. Member38is disposed axially between bearings16and18and is configured to retain and position bearings16,18. A spacer44may be disposed between the head of fastener42and one end of member36and may define a shoulder opposite member38to retain and position bearing18on hub12. Similarly, electromagnet32may define a shoulder opposite member38to retain and position bearing16on hub12. In accordance with one aspect of the disclosed embodiment, hub12eliminates the need for brackets or other supporting structure for the other components of device10.

Output member14is provided to transfer torque to a driven device such as a cooling fan in a vehicle cooling system or to a vehicle alternator or another accessory. Member14may be made from conventional metals and metal alloys. Member14may be disposed about, and centered about, axis34. Member14is disposed at one end of hub12and is supported on hub12for rotation relative to hub12about axis34by bearing18. Member14may define a plurality of threaded bores46in one axial end of member14configured to receive pins28for a purpose described below. In the illustrated embodiment, member14is coupled to a fan coupling48and defines one or more bores50formed in an opposite axial end of member14that are configured to receive fasteners52that couple output member14and coupling48. It should be understood that member14and coupling48could alternatively be formed as a unitary structure. Further, it should be understood that member14could be formed as, or coupled to, a shaft, gear, pulley or other mechanism through which torque may be transferred to a driven device. Member14may be shaped to define one or more shoulders used to retain and position bearings18,20. In the illustrated embodiment, member14defines radially inner and outer shoulders at one axial end that oppose corresponding shoulders formed in coupling46.

Bearings16,18,20are provided to support members of device10and to allow rotation of members of device10relative to other members of device10. Bearings16,18,20may comprise roller bearings or another conventional bearing. Bearing16is disposed proximate on end of hub12and disposed radially between hub12and input member24thereby permitting input member24to rotate relative to hub12. Bearing18is axially spaced from bearing16and is disposed proximate the opposite end of hub12. Bearing18is disposed radially between hub12and output member14thereby permitting output member14to rotate relative to hub12. Bearing20is disposed radially between output member14and input member22thereby permitting input member22to rotate relative to output member14. Bearings18,20may be radially aligned with bearing20disposed radially outwardly of bearing18. In accordance with one advantage of disclosed embodiment, loads resulting from engagement of clutch member26with input member22may be shared among bearings18,20, without any load on bearing16, and axial loads may be accommodated without the use of a thrust bearing. Similarly, loads resulting from engagement of clutch member26with input member24are shared among bearings16,18,20. The axially spaced arrangement of bearings16,18and the location of bearing18proximate the interface of output member14and the fan or other driven device also reduces loads on bearing16resulting from the cantilevered position of the driven device.

Input member22is provided to transfer torque from a driving member to output member14and, as a result, a driven device. Input member22may comprise a pulley driven by a belt coupled to an engine or another source of torque. In one embodiment, member22is driven by an engine accessory belt. Member22is disposed about hub12and is configured to rotate in one rotational direction and at one rotational speed. Member12may be supported on output member14by bearing20and may be disposed radially outwardly of output member14. Member22may be centered about, and configured for rotation about, axis34. In accordance with one aspect of the present teachings discussed in more detail below, member22may define a tapered engagement surface54configured for engagement with clutch member26.

Input member24is also provided to transfer torque from a driving member to output member14and, as a result, a driven device. Input member24may likewise comprise a pulley driven by a belt coupled to an engine or another source of torque. Member24is disposed about hub12and is also configured to rotate in one rotational direction and at one rotational speed. In accordance with aspects of the present teachings, at least one of the rotational direction and rotational speed of input member24may vary relative to the corresponding rotational direction and rotational speed of input member22such that members22,24may, for example, rotate in opposite rotational direction and/or at different speeds. Member24may be centered about, and configured for rotation about, axis34. Member24may be supported on hub12by bearing16for rotation relative to hub12. Member24may be made from metals and metal alloys. Member24includes a radially extending wall56and two axially extending, radially spaced walls58,60at either end of wall56. Walls58,60form radially inner and outer poles and form part of an electromagnetic circuit including electromagnet32, input member24and clutch member26. Wall56defines radially extending, radially spaced surfaces62,64configured for selective frictional engagement with clutch member26. Wall56may include one or more slots66configured to guide the path of magnetic flux between electromagnet32, input member24and clutch member26. These slots66may be formed as one or more radially spaced rows of circumferentially spaced, banana shaped slots.

Clutch member26is provided to couple output member14to either of input members22,24in order to transfer a driving torque from one of input members22,24to output member14and drive output member14in different rotational directions and/or at different speeds. Clutch member26may be annular in shape and may be disposed about, and centered about, axis34. Member26is disposed axially between input members22,24. Member26may include two portions68,70that are proximate to and adjacent to input members24,22, respectively. Portion68may be supported on pins28extending from output member14and may be coupled to output member14for rotation with output member14through pins28. Portion68defines bores72sized to receive pins28and springs30. The diameter of each bore72varies to define a spring seat against which one end of a corresponding spring30is disposed. Portion70is disposed about portion68and supports a friction lining74on a radially outer surface. In accordance with one aspect of the present teachings, portion70of member26—and particularly friction lining74in the illustrated embodiment—tapers and defines a tapered engagement surface76configured for engagement with surface54in input member22. The tapered engagement surfaces54,76enable multiplication of the input torque from input member22. Member26, and particularly portion68of member26, defines radially extending, radially spaced engagement surfaces78,80at an opposite axial end configured for selective frictional engagement with surfaces62,64in input member24. When electromagnet32is deenergized, clutch member26is biased away from input member24by springs30as discussed hereinbelow creating an air gap82between clutch member26and input member24. Portions68,70may be coupled to one another in such a way that the positions of portions68,70relative to one another along axis34may be adjusted to modify gap82without removing device10(or only certain components) from its location within a vehicle or other application environment. The relatively large engagement surfaces62,64,78,80of input member24and clutch member26reduces wear and/or the requirements for any friction materials that may be affixed to input member24and clutch member26thereby improving the cycle life of device10.

Pins28provides a means for coupling clutch member26to output member14. Pins28extend axially from one axial end of output member14into clutch member26. Pins28rotate with output member14and are fixed against axial movement relative to output member14. Pins28are received within bores72of clutch member26such that clutch member26is coupled for rotation with pins28and output member14, but is axially movable relative to pins28and output member14. Alternatively, a spline or key/keyway engagement could be provided between clutch member26and output member14to rotatably couple members14,26but allow for axial movement of member26relative member14. Each pin28includes a head84and a shank86. Head84is disposed at one longitudinal end of pin28and defines a spring seat for spring30. Shank86extends axially from head84and terminates in a threaded portion configured to be received within bore46in output member14.

Springs30provide a means for biasing clutch member26in one direction (to the right inFIG. 1). Each springs30is disposed about a shank86of a corresponding pin28between spring seats formed in the head84of pin28and a shoulder formed by the reduction in diameter in bore72. Because the axial position of pin28is fixed relative to output member14, spring30urges clutch member26towards input member22to rotatably couple input member22to output member14and drive output member14in one rotational direction.

Electromagnet32provides a means for urging clutch member26in one axial direction in order to disengage clutch member26from input member22and engage input member24. Electromagnet32is supported on hub12and is disposed on an opposite side of input member24relative to clutch member26. Electromagnet32is disposed about, and may be centered about, axis34. Electromagnet32includes a field shell88and a conductor90. Field shell88may be annular in shape with an inner diameter sized to receive hub12such that field shell88is supported on hub12. Field shell88includes a radially extending wall92and two radially spaced, axially extending walls94,96that together define a recess configured to receive conductor90. Walls94,96also form radially inner and outer poles and form part of an electromagnetic circuit including electromagnet32, input member24and clutch member26. Walls94,96are radially aligned with and proximate to walls58,60in input member24. Wall92may further define a radially outer flange (not shown) configured to receive one or more fasteners such that wall92functions as a bracket used to mount device10to another structure. Conductor90is provided to create an electromagnetic circuit among field shell88, input member24and clutch member26in order to cause clutch member26to move in one axial direction (to the left inFIG. 1) and into frictional engagement with input member24in order to couple output member14to input member24for rotation therewith. Conductor90may comprise a conventional copper coil although other conventional conductors may alternatively be used. Conductor90is disposed within field shell88radially between walls94,96. Leads from conductor90may be routed through openings in field shell88for connection to a power source and to a grounding member98into which fastener42may be inserted. In this manner, the leads are located in a stationary component and away from rotating components including the driven device coupled to output member14and the driving devices (e.g., belts) coupled to input members22,24.

In operation, in the absence of energizing electromagnet32, springs30urge clutch member26in one axial direction (to the right inFIG. 1) and into engagement with input member22to couple clutch member26—and, as a result, output member14—to input member22for rotation therewith. In this manner, output member14may be driven in one rotational direction and/or at one rotational speed. In one potential application, output member14may be coupled to a cooling fan in a vehicle and the rotational coupling of output member14with input member22drives the fan to provide cooling to vehicle system components. In another potential application, output member14may be coupled to an alternator or other vehicle accessory and the rotational coupling of output member14with input member22drives the alternator or accessory at a first speed. When electromagnet32is energized, an electromagnetic circuit is formed between field shell88, input member24, and clutch member26. This circuit urges clutch member26in an opposite axial direction (to the left inFIG. 1)—overcoming the biasing force of spring30—and into engagement with input member24to couple clutch member26—and, as a result, output member14—to input member24for rotation therewith. In this manner, output member14may be driven in a different rotational direction and/or at a different speed. In one potential application, the rotational coupling of output member14with input member24enables reverse rotation of a cooling fan to expel heat from a vehicle and/or contaminants from the radiator in a vehicle. In another potential application, the rotational coupling of output member14with input member24enables device10to drive an alternator or another vehicle at a different speed.

A rotational coupling device10in accordance with the present disclosure is advantageous relative to conventional coupling devices. In particular, the disclosed coupling device enables transfer of torque from either of two input members22,24to the output member14so that the output member14may be driven in different rotational directions and/or at different speeds. When used to drive a cooling fan, for example, the device10can result in rotation of the fan in either direction to cool vehicle components and to expel heat or contaminants from the vehicle without the use of an additional motor or similar structure. When used to drive an alternator or other vehicle accessory, for example, the device10can drive the alternator or accessory at different speeds during vehicle idling and motion.

While the invention has been shown and described with reference to one or more particular embodiments thereof, it will be understood by those of skill in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.