Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H35/00—Switches operated by change of a physical condition
  • H01H35/24—Switches operated by change of fluid pressure, by fluid pressure waves, or by change of fluid flow
  • H01H35/26—Details
  • H01H35/2607—Means for adjustment of "ON" or "OFF" operating pressure
  • H01H35/2614—Means for adjustment of "ON" or "OFF" operating pressure by varying the bias on the pressure sensitive element

Definitions

• the present invention relates to calibration mechanisms of the cam-type such as are used for pressure switches and, more particularly, to an improved configura ⁇ tion of the camshaft and support bracket which simplifies and facilitates assembly of the mechanism.
• the above and other objects of the present inven ⁇ tion are accomplished by the provision of an improved cal ⁇ ibration mechanism for controlling the setting of a spring biased control member which includes a cam follower.
• the calibration mechanism comprises a support means defining a axial bore and a cam assembly including a cam member de ⁇ fining a cam profile and a camshaft adapted to be received in the bore and to permit the cam assembly to be rotatably disposed in an assembled position with the cam member axially-adjacent the support bracket.
• the cam assembly ha a range of rotational orientations, when the cam assembly in the assembled position, in which the cam follower is in following engagement with the cam profile.
• the cam assemb also has an assembly orientation, rotatably displaced from the range of rotational orientations.
• the camshaft has a projection extending radially therefrom, and axially space from the cam member, and the support bracket defines a slot in communication with the bore.
• the slot is circumferentially oriented to receive the projection when the cam assembly is in the assembly orientation and permits the projection to pass axially therethrough as the cam assembly is moved axially to the assembled position.
• the support bracket and slot are configured to permit rotations of the cam assembly, when the cam assembly is in the assembled position, to the range of rotational orienta- tions. In this condition, the projection is out of circum ⁇ ferential alignment with the slot and prevents substantial axial movement of the cam assembly.
• a second embodiment of the invention incorporates an actuator arm having a bore and a slot communicating therewith for receiving the camshaft and projection.
• the actuator arm also defines a radial projection circumfer ⁇ entially and axially aligned with the projection on the cam-' shaft.
• the actuator arm is spring-biased to a predetermined angular position with respect to the support bracket in which the projection on the shaft is disengaged from the projection on the actuator arm and also angularly offset from the actuator arm slot.
• Fig. 3 is a partial view taken along section lines 3-3 of Fig. 1;
• a calibration mechanism mounted on a pressure switch 12.
• the calibration mechanism 10 in- eludes a pivotally mounted lever 14, a cam member 16, a cam ⁇ shaft 18, and a support bracket indicated generally by refer ⁇ ence numeral 20.
• the pressure switch 12, forming no part of this invention, includes a spring-biased plunger 22 slidably received in a bore 24 formed in an upper housing section 26 of pressure switch 12.
• a biasing spring 28 has its upper end reacting against the bottom surface of plunger 22 and its bottom end reacting against the top sur ⁇ face of an actuator member 30.
• a switch blade (not shown) is disposed intermediate the bottom surface of actuator 30 and the top surface of a diaphragm (not shown) .
• the dia ⁇ phragm is responsive to pressures developed by varying water levels.
• a second biasing spring 32 is mounted between upper housing 26 and lever 14 and functions to continuously maintain an upward biasing force -upon the lever 14.
• Lever 14 is pivot- ally mounted at its right end by a fastener 34 having a spherical head 36 which seats against a corresponding spher ⁇ ical follicle 38 having a central opening 40 through which fastener 34 is received.
• a cam follower 42 is formed by the left end of lever 14 and is continuously biased against cam 16 by spring 32 and, during a portion of its pivotal movement, by spring 28.
• a pair of downwardly extending tabs 44 engage the top surface of plunger 22.
• Support bracket 20 includes outer and inner verti ⁇ cal legs 44 and 46, having bores 48 and 50, respectively, which are horizontally aligned and also in line with a cen ⁇ tral longitudinal axis through lever 14.
• Inner vertical leg 46 includes a vertically extending slot 52 having cam follower
• a radially extending projection 56 is formed on camshaft 18 and has a width permitting entry through keyhol slot 54.
• the right transverse edge of projection 56 with respect to Fig. 2 is spaced from the face of cam 16 a prede mined amount in order to establish desired camshaft end pla with respect to bracket 20.
• cam 16, projection 56 and camshaft 18 are in tegrally molded in one piece from a suitable plastic materi This feature of the invention eliminates the need for lubri cating the camshaft and cam member.
• a material found to be particularly suitable is marketed under the trademark "ZYTEL" by ⁇ . I. du Pont de Nemours, Wilmington, Delaware.
• cam member 16 defines first and second radially extending stop surfaces 58 and 60 respectively, which abut the sides of cam follower 42 and function to limit the angular displacement of camshaft 18.
• a circular bead 61 is formed on the transverse face of cam member 16 and provides a bearing surface for contacting against inner leg 46.
• Projection 56 is angularly positione within that portion of the cam profile between stop surface 58 and 60 not contacted by follower 42.
• Keyhole slot 54 aligned with follower 42, remains continuously offset from projection 56.
• camshaft 18 is axially retained in bore 50 with inner vertical leg 46 being captured between projection 56 and cam 16. End play of camshaft 18 can ther fore be determined by establishing the axial space between projection 56 and the face of cam 16 to an amount slightly greater than the thickness of inner vertical leg 46.
• the calibration mechanism is assembled by first aligning projection 56 with keyhole slot 54 and inserting camshaft 18 through bores 50 and 48 of support bracket 20 until projection 56 clears slot 54.
• Support bracket 20 with the camshaft mounted therein is then attached to the upper housing section 26 of the pressure switch.
• Lever 14 is then aligned over plunger 22 and biasing spring 32 so that cam follower 42 extends into slot 52 and engages with the cam profile of cam section 16.
• Fastener 34 is then in- serted through opening 40 in lever 14 and threaded into upper housing section 26.
• Cam follower 42 is now continu ⁇ ously in engagement with cam 16, thereby limiting the total angular displacement of the cam to an angle defined between first and second stop positions 58 and 60.
• actuator arm 62 rotatably mounted on camshaft 64 through a bore 66.
• actuator arm 62 includes a counterbore 68 which terminates in a transverse shoulder 70.
• a slot 72 extends axially through shoulder 70 and permits projection 76 to pass therethrough.
• a projection 74 extends inward radially from bore 68.
• cam ⁇ shaft 64 has a radial projection 76 extending therefrom an amount sufficient to clear bore 68 when the actuator arm is positioned on camshaft 64.
• the actuator arm projection 74 and the camshaft projection 76 are axially aligned.
• Actuator arm 62 is biased in the posi ⁇ tion as shown by Fig. 5 and has a connecting linkage 78 attached to its free end with the other end of the linkage (not shown) connected to an associated appliance control member.
• camshaft 64 can only rotate initially in a counterclock ⁇ wise direction. Continued counterclockwise rotation of cam- shaft 64 results in projection 76 rotating away from slot 72
• cam ⁇ shaft 64 is then effective to rotate actuator arm 62 counterclockwise for the remaining portion of cam displac ment until stop surface 60 abuts follower 42.
• Shoulder 7 prevents projection 76 from passing through keyhole slot (identical to first embodiment) as it rotates past align ⁇ ment therewith.
• the second embodiment of the invention is assembl in a manner identical to that described for the first em ⁇ bodiment wherein projection 76 is aligned with slot 52 in the support bracket and actuator arm 62 is rotated to per mit projection 76 to pass through slot 72.
• the support bracket is then attached to the pressure switch followed assembly of lever 14.

Landscapes

• Physics & Mathematics (AREA)
• Fluid Mechanics (AREA)
• Gears, Cams (AREA)
• Measuring Fluid Pressure (AREA)
• Switches Operated By Changes In Physical Conditions (AREA)
• Valve-Gear Or Valve Arrangements (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=25428545

Family Applications (1)

Country Status (7)

Cited By (1)

Citations (4)

Family Cites Families (3)

• 1979
  • 1979-04-30 WO PCT/US1979/000285 patent/WO1979001143A1/en unknown
  • 1979-04-30 JP JP50090179A patent/JPS55500374A/ja active Pending
  • 1979-05-16 CA CA327,691A patent/CA1108673A/en not_active Expired
  • 1979-05-28 IT IT23053/79A patent/IT1193793B/it active
  • 1979-05-29 ES ES480991A patent/ES8100543A1/es not_active Expired
  • 1979-05-29 AU AU47520/79A patent/AU4752079A/en not_active Abandoned
• 1980
  • 1980-01-03 EP EP79900613A patent/EP0016780A1/en not_active Withdrawn

Patent Citations (4)

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