Magnetic clutch with adjustable slip torque

• US 5,158,279 A
• Filed: 09/30/1991
• Issued: 10/27/1992
• Est. Priority Date: 09/30/1991
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Garavuso, Gerald, Laffey, Kathleen M., Martin, Michael J., Sokac, Russell J., Durfey, Lloyd W.
• Primary Examiner(s): Skaggs, H. Grant
• Assistant Examiner(s): DRUZBICK, CAROL L
• Application Number:
  US07/767,455
• Time in Patent Office: 393 Days
• Field of Search: 271/114, 271/116, 271/121, 271/122, 271/272, 192/84 PM, 192/110 R, 494/29
• US Class Current: 271/272
• CPC Class Codes: B65H 2220/01 indicating an entity as a function of which control, adjustment or change is performed, i.e. input
• CPC Class Codes: B65H 2220/02 indicating an entity which is controlled, adjusted or changed by a control process, i.e. output
• CPC Class Codes: B65H 2220/08 for distinguishing changing an entity in function of another entity purely by mechanical means, i.e. no electronics involved
• CPC Class Codes: B65H 2220/11 indicating that the input or output entities exclusively relate to machine elements
• CPC Class Codes: B65H 2403/70 Clutches; Couplings
• CPC Class Codes: B65H 2404/1374 means for varying longitudinal length
• CPC Class Codes: B65H 2404/165 braking roller
• CPC Class Codes: B65H 2511/212 Rotary position
• CPC Class Codes: B65H 2511/524 Multiple articles, e.g. double feed
• CPC Class Codes: B65H 27/00 Special constructions, e.g. surface features, of feed or guide rollers for webs rollers in general F16C13/00
• CPC Class Codes: B65H 3/5261 Retainers of the roller type, e.g. rollers
• CPC Class Codes: B65H 7/12 responsive to double feed or separation
• CPC Class Codes: F16D 43/21 with friction members slip couplings of the friction type F16D7/02
• CPC Class Codes: H02K 49/104 Magnetic couplings consisting of only two coaxial rotary elements, i.e. the driving element and the driven element
• CPC Class Codes: H02K 49/106 with a radial air gap

Abstract

A magnetic clutch provides an adjustable slip torque. A housing, having an outer surface of a predetermined frictional coefficient, is disposed around a portion of a shaft, and is rotatable relative to the shaft An outer magnetic member is disposed on the inner surface of the housing, and an inner magnetic member is attached to the shaft and disposed within the housing. The slip torque is adjusted by varying the amount of surface area exposure between the inner magnetic member and the outer magnetic member.

Claims

1. A magnetic clutch providing an adjustable slip torque, comprising:

a shaft;

a housing disposed around at least a portion of the shaft, rotatable relative to the shaft, having an outer surface of a predetermined frictional coefficient, and an inner surface;

at least one outer magnetic member, disposed on the inner surface of the housing;

at least one inner magnetic member attached to the shaft, and disposed within the housing, defining a plurality of outwardly-facing discrete areas of ferromagnetic polarity arranged radially relative to the shaft; and

means for varying the amount of surface area exposure between the inner magnetic member and the outer magnetic member, thereby facilitating adjustment of the slip torque between the shaft and the housing, including means for moving the inner magnetic member axially relative to the outer magnetic member.

2. A magnetic clutch as in claim 1, wherein the outer magnetic member defines a plurality of inwardly-facing discrete areas of ferromagnetic polarity arranged radially relative to the shaft.

3. A magnetic clutch as in claim 1, wherein the outer magnetic member defines a central cavity having on an inner surface thereof a plurality of inwardly-facing discrete areas of ferromagnetic polarity arranged radially relative to the shaft, and the inner magnetic member defines a plurality of outwardly-facing discrete areas of ferromagnetic polarity arranged radially relative to the shaft.

4. A magnetic clutch as in claim 3, wherein the housing is axially movable relative to the shaft.

5. A magnetic clutch as in claim 4, further including an external coupling disposed at one end of the shaft external to the housing, the coupling being adapted for maintaining the end of the shaft at a preselected axial position therewithin.

6. A magnetic clutch as in claim 3, further comprising:

at least one end cap, the end cap being threadably mounted at one axial end of the housing for adjustment of the axial position of the end cap relative to the housing, the end cap defining a opening therein; and

a bearing disposed around the opening and around a portion of the shaft, the bearing being adapted to permit rotation of the shaft relative to the housing;

whereby axial adjustment of the end cap causes axial adjustment of the position of the inner magnetic member within the outer magnetic member.

7. A magnetic clutch as in claim 6, further comprising a coil spring disposed within the housing, adapted to urge the housing axially away from the inner magnetic member.

8. A magnetic clutch as in claim 6, including a second opening defined in the end of the housing opposite that of the end cap, the second opening having a second bearing disposed therein, the second bearing permitting axial and rotational relative motion between the shaft and the housing.

9. An apparatus for advancing sheets, comprising:

a rotatable feed roll, having an outer surface of a predetermined frictional coefficient; and

a clutch roll, disposed adjacent to the feed roll and forming a nip therewith for receiving sheets, the clutch roll providing an adjustable slip torque and including

(a) a rotatable shaft,

(b) a housing disposed around a portion of the shaft, rotatable relative to the shaft, having an outer surface of a predetermined frictional coefficient, and an inner surface,

(c) at least one outer magnetic member, disposed on the inner surface of the housing,

(d) at least one inner magnetic member, attached to the shaft and disposed within the housing, and

(e) means for varying the amount of surface area exposure between the outer surface of the inner magnet and the outer magnet, thereby varying the slip torque of the housing relative to the shaft;

whereby the frictional coefficients of the feed roll and the housing of the clutch roll and the slip torque of the clutch roll are related to the frictional coefficient of sheets passing through the nip so that a single sheet passing through the nip will be engaged by the feed roll and the housing of the clutch and multiple sheets passing through the nip will slide relative to each other and cause the housing of the clutch roll to rotate relative to the shaft.

10. An apparatus as in claim 9, wherein at least one of the outer magnetic member and the inner magnetic member of the clutch roll is a permanent magnet.

11. An apparatus as in claim 9, wherein the feed roll drives the clutch roll in a direction consistent with motion of a sheet through the nip.

12. An apparatus as in claim 9, wherein the means in the clutch roll for varying the amount of surface area exposure between the inner magnetic member and the outer magnetic member includes means for moving the inner magnetic member axially relative to the outer magnetic member.

13. An apparatus for advancing sheets, comprising:

a rotatable feed roll, having an outer surface of a predetermined frictional coefficient; and

a clutch roll, disposed adjacent to the feed roll and forming a nip therewith for receiving sheets, the clutch roll providing an adjustable slip torque and including;

(a) a rotatable shaft,

(b) a housing disposed around a portion of the shaft, rotatable relative to the shaft, having an outer surface of a predetermined frictional coefficient, and an inner surface,

(c) at least one outer magnetic member, disposed on the inner surface of the housing defining a central cavity having on an inner surface thereof a plurality of inwardly-facing discrete areas of ferromagnetic polarity arranged radially relative to the shaft,

(d) at least one inner magnetic member, attached to the shaft and disposed within the housing, wherein the inner magnetic member defines a plurality of outwardly-facing discrete areas of ferromagnetic polarity arranged radially relative to the shaft, and

(e) means for varying the amount of surface area exposure between the outer surface of the inner magnet and the outer magnet, thereby varying the slip torque of the housing relative to the shaft;

whereby the frictional coefficients of the feed roll and the housing of the clutch roll and the slip torque of the clutch roll are related to the frictional coefficient of sheets passing through the nip so that a single sheet passing through the nip will be engaged by the feed roll and the housing of the clutch and multiple sheets passing through the nip will slide relative to each other and cause the housing of the clutch roll to rotate relative to the shaft.

14. An apparatus for advancing sheets, comprising:

a rotatable feed roll, having an outer surface of a predetermined frictional coefficient; and

a clutch roll, disposed adjacent to the feed roll and forming a nip therewith for receiving sheets, the clutch roll providing an adjustable slip torque and including;

(a) a rotatable shaft,

(b) a housing disposed around a portion of the shaft, rotatable relative to the shaft, having an outer surface of a predetermined frictional coefficient, and an inner surface,

(c) at least one outer magnetic member, disposed on the inner surface of the housing,

(d) at least one inner magnetic member, attached to the shaft and disposed within the housing, and

(e) means for varying the amount of surface area exposure between the outer surface of the inner magnet and the outer magnet, thereby varying the slip torque of the housing relative to the shaft,

(f) at least one end cap, the end cap being threadably mounted at one axial end of the housing for adjustment of the axial position of the end cap relative to the housing, the end cap defining an opening therein, and

(g) a bearing disposed around the opening and around a portion of the shaft, the bearing being adapted to permit rotation of the shaft relative to the housing, whereby axial adjustment of the end cap causes axial adjustment of the position of the inner magnetic member within the outer magnetic member;

whereby the frictional coefficients of the feed roll and the housing of the clutch roll and the slip torque of the clutch roll are related to the frictional coefficient of sheets passing through the nip so that a single sheet passing through the nip will be engaged by the feed roll and the housing of the clutch and multiple sheets passing through the nip will slide relative to each other and cause the housing of the clutch roll to rotate relative to the shaft.