US3721780A - Limit switch assembly including rotatable cam with longitudinally guided indexing nut and cam longitudinal displacement means - Google Patents

Limit switch assembly including rotatable cam with longitudinally guided indexing nut and cam longitudinal displacement means Download PDF

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Publication number
US3721780A
US3721780A US00140192A US3721780DA US3721780A US 3721780 A US3721780 A US 3721780A US 00140192 A US00140192 A US 00140192A US 3721780D A US3721780D A US 3721780DA US 3721780 A US3721780 A US 3721780A
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US
United States
Prior art keywords
lead screw
cam body
indexing nut
indexing
rotation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00140192A
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English (en)
Inventor
R Kelly
D Ward
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Borg Warner Corp
Original Assignee
Borg Warner Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
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Publication of US3721780A publication Critical patent/US3721780A/en
Assigned to BORG-WARNER CORPORATION, A DE CORP. reassignment BORG-WARNER CORPORATION, A DE CORP. ASSIGNMENT OF ASSIGNORS INTEREST. EFFECTIVE AS OF DEC. 31, 1987 Assignors: BORG-WARNER AUTOMOTIVE, INC., A DE CORP.
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05G—CONTROL DEVICES OR SYSTEMS INSOFAR AS CHARACTERISED BY MECHANICAL FEATURES ONLY
    • G05G15/00—Mechanical devices for initiating a movement automatically due to a specific cause
    • G05G15/04—Mechanical devices for initiating a movement automatically due to a specific cause due to distance or angle travelled by a member
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q15/00—Automatic control or regulation of feed movement, cutting velocity or position of tool or work
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23Q—DETAILS, COMPONENTS, OR ACCESSORIES FOR MACHINE TOOLS, e.g. ARRANGEMENTS FOR COPYING OR CONTROLLING; MACHINE TOOLS IN GENERAL CHARACTERISED BY THE CONSTRUCTION OF PARTICULAR DETAILS OR COMPONENTS; COMBINATIONS OR ASSOCIATIONS OF METAL-WORKING MACHINES, NOT DIRECTED TO A PARTICULAR RESULT
    • B23Q15/00—Automatic control or regulation of feed movement, cutting velocity or position of tool or work
    • B23Q15/20—Automatic control or regulation of feed movement, cutting velocity or position of tool or work before or after the tool acts upon the workpiece
    • B23Q15/22—Control or regulation of position of tool or workpiece
    • B23Q15/26—Control or regulation of position of tool or workpiece of angular position
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H25/00—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms
    • F16H25/18—Gearings comprising primarily only cams, cam-followers and screw-and-nut mechanisms for conveying or interconverting oscillating or reciprocating motions
    • F16H25/20—Screw mechanisms
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B19/00—Programme-control systems
    • G05B19/02—Programme-control systems electric
    • G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
    • G05B19/06—Programme control other than numerical control, i.e. in sequence controllers or logic controllers using cams, discs, rods, drums or the like
    • G05B19/063—Programme control other than numerical control, i.e. in sequence controllers or logic controllers using cams, discs, rods, drums or the like for sequential programme-control without delivering a reference value

Definitions

  • a switch assembly provides position signals from a series of switches as a function of motor shaft rotation.
  • a lead screw rotated as a function of motor shaft rotation, includes an exterior threaded surface and a plurality of longitudinal slots.
  • An indexing nut rides on the lead screw, but the indexing nut is restrained against rotation.
  • a rotatable cam body has a plurality of drive tangs which extend into the lead screw slots, to afford rotation of the cam body in accordance with lead screw rotation.
  • a bearing with a pair of snap rings translates the longitudinal movement of the indexing nut into a corresponding longitudinal displacement of the cam body.
  • the cam has a lobe positioned to contact and selectively actuate the extending portions of a series of switches as the cam body is rotated and displaced lengthwise.
  • the switch assembly of this invention is useful for providing control signals as a function of angular motion to indicate length of longitudinal displacement derived from the angular motion, for example, when a motor drives a carriage or other unit.
  • the switch assembly includes a lead screw, which has a first portion positioned to receive rotational drive similar to the angular rotation of the motor shaft.
  • the lead screw includes a second portion, which is threaded on its exterior, and the threads are interrupted to define at least one longitudinal slot.
  • An indexing nut is provided, and has a threaded bore portion dimensioned to receive the exterior threads of the lead screw. Means is provided to prevent rotation of the indexing nut as it is displaced longitudinally by rotation of the lead screw.
  • this means included a pin extending from the indexing nut into a guide slot provided in the switch body.
  • a cam body is provided with at least one interior tang portion extending into the longitudinal slot of the lead screw.
  • the cam body also includes an exterior lobe.
  • Means is also provided to effect longitudinal displacement of the cam body as a function of the longitudinal displacement of the indexing nut.
  • this means included a bearing and a pair of end pins, one pin in the indexing nut and one in the cam body, so that the longitudinal motion is transferred while the cam body is rotated.
  • a plurality of switches are provided, with their actuating portions extending adjacent the path of travel of the lobe on the cam body. In this way selective actuation of the switches is provided by the cam lobe as it is moved along its path of travel. Control signals are provided to regulate associated equipment as the lead screw is rotated in accordance with angular motion of a motor shaft or any other rotational signal.
  • FIG. 1 is a block diagram indicating the employment of this invention in a larger system
  • FIG. 2 is a side view, partly in section and partly broken away, illustrating details of the switch assembly of this invention.
  • FIG. 1 depicts a motor control arrangement in which the switch assembly of this invention is useful.
  • a motor 11 is energized over line 12, relay 13, and power input line 14.
  • motor 11 provides mechanical power to a load (not shown) over a shaft 15, and the angular motion of shaft 15 is translated over shaft extension 16, flexible coupling 17, and shaft 18 to switch assembly 10.
  • shafts l5 and 16 can be the same component, or a pulley, sprocket arrangement, or other system can be utilized to drive input shaft 18 of the switch assembly as a function of the rotation of motor shaft 15.
  • Switch assembly 10 has a plurality of output conductors 20, shown gathered into a single cable 21, to transfer position-indicating control signals to a control circuit 22, which also includes a knob 23 or other arrangement for pre-setting a desired location signal. Responsive to coincidence between the preset location signal received over knob 23 and the instantaneous position signal on cable 21, control circuit 22 provides an output signal over conductor 24 to activate relay 13 and interrupt energization of motor 11.
  • control circuit 22 provides an output signal over conductor 24 to activate relay 13 and interrupt energization of motor 11.
  • Other system configurations will be suggested to those skilled in this art.
  • the present invention resides principally in the construction of switch assembly 10, to receive a mechanical input signal denoting angular movement over shaft 18, and provide output control signals over conductors 20 to afford a precise indication of the input shaft displacement.
  • switch assembly 10 includes a cup-shaped housing 25 and a cover plate 26, affixed to housing 25 by a pair of fastening screws 27. Only one fastening screw is visible in FIG. 2.
  • a lead screw 28 has a first portion 18 extending through a bore of cover plate 26 to receive rotational drive which is a function of the angular displacement of motor shaft 15.
  • Lead screw 28 also includes a threaded portion 30, and at least one cam drive slot 31 which extends along the body of the lead screw and interrupts the threads. In a preferred embodiment four slots 31 were provided at intervals around the lead screw.
  • the right end portion of lead screw assembly 28 includes a reduceddiameter end 50, received in a bearing 51 which in turn is snuggly fitted into a bore in the end of housing 25.
  • a washer 52 and a nut 53 are provided to secure the right end of the lead screw assembly in position.
  • the other end of the lead screw assembly, where it enters cover plate 26, is received in another bearing 54.
  • indexing nut 32 has its bore portion tapped for mating engagement with lead screw threads 30, so that ordinarily the indexing nut would turn freely on the lead screw.
  • an indexing pin 33 has one end anchored in indexing nut 32 as shown, and the other end of pin 33 is received in a guide slot 34 defined in the interior surface of housing 25. Accordingly pin 33 and slot 34 cooperate to prevent rotation of the indexing nut; with rotation of lead screw assembly 28, indexing nut 32 is displaced longitudinally.
  • a cam body 35 is provided with at least one exterior lobe 36.
  • the cam body is generally C-shaped (in section) as shown, and includes at least one tang or spline 37, sized to fit in longitudinal slot 31 of the lead screw assembly 28. In a preferred embodiment four tangs were provided, one tang being indexed in each of the four slots 31. Accordingly cam body 35 is rotated by angular movement ofthe lead screw assembly.
  • a bearing 38 is disposed between cam body 35 and indexing nut 32.
  • the interior surface of bearing 38 is received against a shoulder portion of nut 32 and held in place by a snap ring 40.
  • the outer portion of bearing 38 is similarly received in a cut-down portion of cam body 35 and held by a snap ring 41.
  • bearing 38 cooperates with snap rings 40, 41 to provide a longitudinal displacement of cam body 35 as a function of longitudinal displacement of indexing nut 32.
  • cam body 35 is both rotated and moved longitudinally.
  • cam lobe 36 describes a spiral path of travel to sequentially engage the actuator portions 42 of each switch unit 43 as the lobe passes adjacent that switch unit.
  • the control signal signifying shaft position is provided by displacement of the actuator. If desired this mechanical signal can be utilized for example, as a control signal for a fluid valve.
  • switch 43 is of the type which provides an electrical signal at a pair of contacts 44, 45 to which the conductors shown generally as lines 20 in FIG. 1 can be attached.
  • a pair of mounting plates 46 is provided; only one plate is visible in FIG. 2.
  • Each switch mounting plate 46 is affixed by screws (not shown) within housing 25.
  • a mounting screw 47 and spring 48 are provided so that the position of each switch can be simply and swiftly adjusted.
  • the switch assembly By providing the combination of lead screw, nonrotating indexing nut, and a cam body which moves both longitudinally and rotationally, the switch assembly signals the carriage location with a high degree of accuracy.
  • accuracy of the order of 4% was achieved to signal the carriage position.
  • accuracies of the order of 0.1 percent can be achieved.
  • the switch assembly of this invention has few parts, and is readily assembled and installed.
  • the indexing cam can provide a signal for both directions of rotation.
  • the cam must have equal approach and fall-off slope angles with approximately 3.6 of switch actuation cam rotation angle to provide an accuracy of 0.1 percent in 3,600 degrees of total input shaft rotation.
  • a switch assembly for providing control signals as a function of angular motion comprising:
  • a lead screw having a first portion positioned to receive rotational drive, and a second portion which is both threaded and defines at least one longitudinal slot;
  • an indexing nut having a threaded bore portion dimensioned to receive the exterior threads of the lead screw
  • cam body spaced from the indexing nut, including at least one interior tang portion extending into the longitudinal slot of the lead screw, and having at least one exterior lobe;
  • a plurality of switches disposed adjacent the path of travel of the lobe on the cam body, for selective actuation by the lobe to provide the control signals as the lead screw is rotated.
  • a switch assembly as claimed in claim 1, in which the means for preventing rotation of the indexing nut includes a guide slot in the switch assembly, and an indexing pin, having one end received in the indexing nut and the other end extending into the guide slot, thus to prevent rotation of the indexing nut as it is driven by rotation of the lead screw.
  • a switch assembly as claimed in claim 1, in which the means for effecting longitudinal displacement of the cam body includes a bearing, positioned between the cam body and the indexing nut, and a pair of snap rings, to assist in translating the longitudinal motion of the indexing nut to the cam body.
  • a switch assembly for providing control signals to de-energize a motor responsive to a preassigned rotational displacement of the motor shaft, comprising:
  • a lead screw having a first portion positioned to receive rotational drive as a function of motor shaft rotation, and a second portion which is both threaded and defines a plurality of longitudinal slots;
  • an indexing nut having a threaded bore portion dimensioned to receive the exterior threads of the lead screw
  • a cam body including a plurality of interior tangs exa plurality of electro-mechanical switches having tending into the respective longitudinal SlOtS Of the their respective actuator portions disposed adlead screw, and having at least one exterior lobe; means, including a bearing having its inner portion received in the indexing nut and its outer portion 5 received in the cam body, for translating longitu- Slgnals. as the lead Screw. ls rotated m acdinal displacement of the indexing nut into loncordance wlth motor Shaft rotation gitudinal displacement of the cam body; and

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • General Engineering & Computer Science (AREA)
  • Transmission Devices (AREA)
US00140192A 1971-05-04 1971-05-04 Limit switch assembly including rotatable cam with longitudinally guided indexing nut and cam longitudinal displacement means Expired - Lifetime US3721780A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US14019271A 1971-05-04 1971-05-04

Publications (1)

Publication Number Publication Date
US3721780A true US3721780A (en) 1973-03-20

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Application Number Title Priority Date Filing Date
US00140192A Expired - Lifetime US3721780A (en) 1971-05-04 1971-05-04 Limit switch assembly including rotatable cam with longitudinally guided indexing nut and cam longitudinal displacement means

Country Status (8)

Country Link
US (1) US3721780A (it)
AT (1) AT315950B (it)
CA (1) CA946890A (it)
DE (1) DE2221385C3 (it)
FR (1) FR2135298A1 (it)
GB (1) GB1335649A (it)
IT (1) IT955211B (it)
NL (1) NL7205503A (it)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2841250A1 (de) * 1978-09-11 1980-04-17 Semenov Programmschaltgeraet
US4644113A (en) * 1985-10-09 1987-02-17 Huang L D Electric safety device
US5506377A (en) * 1993-10-12 1996-04-09 Emerson Electric Co. Limit switch carrier assembly
US20130059684A1 (en) * 2010-05-26 2013-03-07 Toyota Jidosha Kabushiki Kaisha Belt type continuously variable transmission
CN105195786A (zh) * 2015-11-11 2015-12-30 自贡德沃机械制造有限公司 曲轴油孔钻孔装置
CN106298302A (zh) * 2016-10-25 2017-01-04 中国电建集团成都勘测设计研究院有限公司 行程限位开关装置

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19634308A1 (de) * 1996-08-24 1998-02-26 Roemheld A Gmbh & Co Kg Wegmeßsystem für Lineareinheiten
DE102005057227B4 (de) * 2005-11-29 2011-07-21 PIRAS Metalltechnik GmbH & Co. KG, 95163 Vorrichtung zur Erzeugung einer Linearbewegung

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2951920A (en) * 1957-07-15 1960-09-06 Vemco Products Inc Rotary limit switch
US3462563A (en) * 1968-01-08 1969-08-19 Superior Electric Co Tap changing mechanism with scotch yoke actuator
US3523599A (en) * 1969-07-15 1970-08-11 King Of Prussia Research & Dev Linear actuator with torque control

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2951920A (en) * 1957-07-15 1960-09-06 Vemco Products Inc Rotary limit switch
US3462563A (en) * 1968-01-08 1969-08-19 Superior Electric Co Tap changing mechanism with scotch yoke actuator
US3523599A (en) * 1969-07-15 1970-08-11 King Of Prussia Research & Dev Linear actuator with torque control

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2841250A1 (de) * 1978-09-11 1980-04-17 Semenov Programmschaltgeraet
US4241245A (en) * 1978-09-11 1980-12-23 Pevzner Volf S Programmed switching device
US4644113A (en) * 1985-10-09 1987-02-17 Huang L D Electric safety device
US5506377A (en) * 1993-10-12 1996-04-09 Emerson Electric Co. Limit switch carrier assembly
US20130059684A1 (en) * 2010-05-26 2013-03-07 Toyota Jidosha Kabushiki Kaisha Belt type continuously variable transmission
US8888617B2 (en) * 2010-05-26 2014-11-18 Toyota Jidosha Kabushiki Kaisha Belt type continuously variable transmission
CN105195786A (zh) * 2015-11-11 2015-12-30 自贡德沃机械制造有限公司 曲轴油孔钻孔装置
CN106298302A (zh) * 2016-10-25 2017-01-04 中国电建集团成都勘测设计研究院有限公司 行程限位开关装置

Also Published As

Publication number Publication date
CA946890A (en) 1974-05-07
FR2135298A1 (it) 1972-12-15
IT955211B (it) 1973-09-29
AT315950B (de) 1974-06-25
DE2221385A1 (de) 1972-11-16
GB1335649A (en) 1973-10-31
DE2221385B2 (de) 1974-01-31
NL7205503A (it) 1972-11-07
DE2221385C3 (de) 1974-08-29

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Legal Events

Date Code Title Description
AS Assignment

Owner name: BORG-WARNER CORPORATION, A DE CORP.

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. EFFECTIVE AS OF DEC. 31, 1987;ASSIGNOR:BORG-WARNER AUTOMOTIVE, INC., A DE CORP.;REEL/FRAME:005287/0001

Effective date: 19881122