US 3577625 A
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United States Patent App]. No. Filed Patented Assignee PROCESS AND MECHANISM FOR SETTING IGNITION DISTRIBUTOR CEN'I'RIFUGAL ADVANCE Primary Examiner-Francis S. Husar Assistant Examiner-l. R. Bilinsky Attorneys-John R. Faulkner and Glenn S. Arendsen ABSTRACT: Tabs determining the amount of centrifugal advance are adjusted during distributor rotation at various speeds by applying appropriate hammer blows to a mechanism 11 Claims 4 Drawing Figs rotating with the distributor shaft assembly. The hammer US. Cl 29/4071', blows are applied to concentric anvil members projecting 29/2031, 324/16, 73/118 from the top of the mechanism and are transmitted by mem- Int. Cl F02p 17/00 bers located within the mechanism to pins positioned adjacent Field of Search 29/203 (P), the tabs. A photoelectric system senses the amount of advance 407, 593; 73/540, 118, (inquired); 324/ 1.6, at various rotating speeds and automatically controls the ap- (lnquired, 15, 28 plication of the hammer blows.
LIFT M EC H A94 HA/MMER ACTUATIN G 24 Q" CIR cu T i j /3/ t L- 1 w i i I l Ai'z I I 1 L I l DRIVE MOTOR |----LELECT-RON1C C|RCU|T]- J BACKGROUND OF THE INVENTION Modern ignition distributors use a combination of centrifugal and pneumatic advancing systems to matchignition timing to engine requirements throughout the entire speed range. Centrifugal advance is achieved by building the distributor shaft assembly intwo parts, one driven directly by the engine and the second driven through weights mounted on the first part. Movement of the weights under the influence of centrifugal forces moves the second part relative to the first as a function of engine speed.
Recently legislated exhaust ignition standards have necessitated more careful control over ignition timing. Where tab settings previously could be made according to a mechanical standard and the completed shaft assembly merely checked to insure that centrifugal advance was within a relatively wide range, it has become necessary to position the tabs on each individual distributor to conform the centrifugal advance to individual distributor characteristics.
SUMMARY OF THE INVENTION This invention provides a system for bending the tabs into the proper position while the distributor shaft assembly is rotating at any predetermined speed. Variations from the I desired advance are sensed automatically and the tabs areadthe rotationalaxis of the shaft assembly, and a pin movably by the anvil is positioned adjacent one side of the tab. An electric or hydraulic motor rotates the shaft assembly and housing at a predetermined speed. The relative position of the two parts of the shaft assembly is measured by a sensingsystem and the signals from the sensing system are applied to a hammer positioned above the anvil. If the two parts of the shaft assembly are not at a predetermined relative position, the signals actuate the hammer to apply impacts to the anvil. These impacts are transmitted to the pin which contacts the tab and bends the tab to the desired position. Distributor rotational speed .then can be varied to check conformance of the centrifugal advance to the specified values at all other rotational speeds.
Distributor shaft assemblies generally contain one tab for adjusting centrifugal advance at low rotational speeds and a second tab for adjusting advance at higher speeds. A second anvil concentric with the first anvil then is mounted in the housing and a second pin positioned adjacent the high-speed tab is contacted by the second anvil. Each tab is adjusted at its own predetermined set speed. After both tabs are adjusted, the distributor is checked for conformance to specification at all other rotational speeds.
A photoelectric system can be used conveniently to sense BRIEF DESCRIPTION OF THE DRAWINGS FIG. 'I is a perspective view of the mechanisms used to carry out this invention. The FIG. shows the housing positioned on a shaft assembly, a hammer mechanism containing concentric hammers positioned above the housing, and the light source and photoelectric cell needed to sense the position of the upper part of the shaft assembly. v
FIG. 2 is a perspective of a conventional distributor shaft assembly showing the advancing weights, springs controlling the weights, and tabs controlling the springs.
FIG. 3 is a sectioned elevation of the housing mounted on A the distributor shaft assembly. The FIG. shows the relative positions of the tabs, pins andanvils. Reset pins capable of bending the tabs in the opposite direction also are shown.
FIG. 4 is a schematic of a photoelectric system capable of sensing the relative positions of the shaft parts and automatically applying hammer blows to achieve the desired positionmg,
DETAILED DESCRIPTION The conventional distributor shaft assembly shown in FIG. 2 comprises a lower part 10 made up a shaft 12 having a plate 14 rigidly fastened thereto at an intermediate location. Shaft 12 projects a short distance above plate 14 and the shaft assembly upper part indicated generally by numeral I6 comprises a slightly larger shaft 18 fitting slidably around the projection of shaft I2. A cam 20 for the breaker points is mounted at an intermediate location on shaft 18 and a notch 22 for receiving a distributor rotor (not shown) is cut into the top of shaft 18. The bottom of shaft I8 is fastened rigidly to a plate 24 that is positioned slidably on the upper surface of plate 14.
:Plate 24 contains two cutouts 26and 28 on diagonally opposite sides of shaft 18. Weight members 30 and 32 are fastened rotatably to plate 14 by pins 34 and 36 and are mounted in respective cutouts 26 and 28. Outer surfaces 38 and 49 of respective weight members 30 and 32 have a predetermined contour that bears against the corresponding surfaces of respective cutouts26 and 28. When the shaft assembly is rotating in the direction of arrow 42, centrifugal forces acting on weights 30 and 32move surfaces 38 and 40 into contact with plate 24. Such contact urges relative movement of plate 24 in the direction of arrow 44, which advances the ignition timing.
A spring 46 has one eye hooked to a post 48 fastened to plate 24 and the other eye hooked to a bendable tab 50 made integrally with plate 14. Similarly, a spring 52 has one eye hooked to a post 54 fastened to plate 24 and the other eye hooked to bendable tab 56 of plate 14. Spring 46 has a relatively low spring rate and resists relative movement of plate 24 in the direction of arrow 44 at low rotational speeds. Spring 52 has a relatively high spring rate but is anchored loosely to post 54 so it does not come into play until some relative movement of plate 24 has occurred The positions of tabs 50 and 56 thus determine the centrifugal advance characteristics of the distributor.
the relative positions of the two parts of the shaft assemblies.
The photoelectric system comprises a light reflector placed in the notch intended for positioning the distributor rotor on the second part of the shaft assembly. A light source is aimed at the reflector through a slot in the side of the housing and a photoelectric device is positioned to receive reflections from the reflector once each revolution. The signal from the photoelectric device and a signal representative of the rotational position of the lower shaft part are applied to electronic circuitry that compares the relative timing of the signals. If the timing varies from a predetermined standard, an output signal is applied to an electrically actuated hammer that applies impacts to the appropriate anvil. Extremely high accuracy can be attained with the photoelectric system since mechanical connections with the second part of the shaft assembly are not required. In place of the auxiliary reflector, a small reflecting pad can be formed on the second part of the shaft assembly.
Turning to FIGS. 1, 3 and 4, the shaft assembly of FIG. 2 is mounted in a support pedestal 60 where shaft 12 is engaged by a drive motor 62. A housing 64 for the tab-bending mechanism has a skirt 65 on its lower end that positions the housing on plate 14. The springs, weights, and tabs of the shaft assembly fit within the space surrounded by skirt 65 and the shaft assembly upper part 16 projects into a cavity 66 formed in the lower part of housing 64. A larger cavity 67 is formed in the upper part of housing 64. Housing 64 rotates with the lower part of the shaft assembly and can be driven through 'contact with appropriate shoulders on plate 14 such as one-end and slides in the lower part of housing 64; Surrounding rod 76 is a compressive spring 78 that-urges crossmember 72 to an upward position. A rod 80 contacts theother side of crossmernber-"IZ and extends downward into the lower part of housing 64. A concentric compressive spring 82 also surrounds rod 80. Springs 78 and 82 combine to keep crossmember 72 perpendicular to the rotational axis of the housing. The lower end of rod 80 has an angled face 82 that is positioned at one end of a lateral passage 84 drilled into housing 64 just above skirt 65.
Mounted slidably in passage 84. is a rod 86 that has a tapered face 88 on its inner end contacting face 82. A pin'90 fastened to rod 86 projects downward through a slot in the bottom of housing 64 and terminates adjacent the inner side of table 56. A compressive spring 92 bears against the end of rod 86 and is held in place by a plug 94.
A rod 96 having a surrounding spring 98 is connected to crossmember 74'and projects downwardly to. housing 64 in a manner similar to rod 80. The guide rod for crossmember 74 has been removed for clarity. Near the bottom of housing 64, a tapered face on the end of rod 96 contacts the tapered face of a horizontal rod (not shown) similar to rod 86. A pin 100 projects through a-slot in the bottom of housing 64 from the horizontal rod and is positioned adjacent the inside surface of tab 50. I
Reset pins 102 and 104 project radially through skirt 65 of the housing and terminate near the outer surfaces of pins 50 and'56 respectively. Compressive spring 106 and 108 urge respective pins 102 and 104 radially outward. Small collars 110 and 112 fastened to respective pins 102 and 104 near the outer ends thereof serve as stops limiting maximum inward movement of the reset pins.
An impacting mechanism 120 is mounted above housing 64. Mechanism 120 contains an inner hammer 122 positioned above anvil 69 and a concentric outer hammer 124'positioned above anvil 70.
Referring primarily to FIGS. 1 and 4, a light source 126 is mounted adjacent housing 64 at the approximate level of a horizontal slot 128 cut into the side of the housing. Slot 128 is at the approximate height of the upper portion of cavity 66. A cap 129 having reflecting surface 130 is mounted on the notch 22 of the upper part of the shaft assembly, and a photoelectric cell 131 is positioned at the same height as slot 128. Cell 131 is aimed at the slot where it will receive light reflected from light source 126 by reflecting surface 130.
Coupled to drive motor 62 and photoelectric cell 131 is an electronic circuit 132 capable'ofdetermining the timing of a signal received from the photoelectric cell relative to a signal received from the drive motor. Circuit132 in turn is coupled via an output lead 133 to a circuit 134 capable of actuating hammer 124 and via an output lead 135 to a similarcircuit (not shown) capable of actuating hammer 122.
During distributor shaft assembly, tabs 50 and 56 are positioned inan attitude inclined inwardly from but reasonably close to the anticipated final attitude. The shaft assembly is mounted in the pedestal and the housing is'mounted on the shaft assembly. Motor 62 drives shaft 12 at the speed of the low speed set point, usually about 300-600 r.p.m. Signals from photocell 131 and signals from the motor representing the position of the lower part of the shaft assembly are compared in circuitry 132, and an output is applied to the circuitcontrolling hammer 122 if the signals vary from the predetermined standard. Hammer 122 applies appropriate impacts to anvil 69, and the impacts are transmitted via crossmember 74, rod 96 and pin 100 to tab 50. When tab 50 has been bent to the position producing the desired amount of advance, circuit 132 automatically stops producing an output signal.
Motor 62 then is operated at the higher set point and the process is repeated using hammer 124 to position tab 56 properly. If the tabs are angled too far outward at the beginning of the settings, motor 62 is stopped and the equipment operator presses reset pins 102 and 104 to bend the tabs inward. The setting process then is repeated to achieve the proper settings. After the settings have been made, the shaft assembly can be rotated at other speeds to check its conformance on the visual display 139 to specification throughout the anticipated speed range.
In place of the auxiliary cap 129, a reflecting surface can be machined on shaft 18. Other position sensing systems actuated mechanically from cam 20 can be used in place of the photoelectric system. A visual display of the relative positions can be provided for an operator who manually applies the impacts. Such a visual display is useful particularly in checking conformance of the distributor to a specification after the'tabs have been set. Hammers 122 and 124 can be actuated pneumatically or hydraulically if desired. A movable cam can be located adjacent the exterior ends of reset pins 102 and 104v where the cam will act through the pins to bend the tabs inward if necessary.
Thus this invention sets the amount of centrifugal advance for each individual ignition distributor rapidly and accurately. The system senses the relative position of the two parts of the distributor shaft assembly at any rotational speed and adjusts the relative position while the shaft is rotating at that speed.
1. A process for bending into position a tab controlling the amount of centrifugal advance in an ignition distributor comprising:
mounting a housing on a rotatable distributor shaft assembly containing said tab, said distributor shaft assembly including a directly rotatable portion and a portion rotatable by said directly rotatable portion through centrifugal means responsive to rotational speed, said housing including an impact receiving means located concentric withthe rotational axis of said shaft assembly and a pin means contacted by said impact receiving means, said pin means positioned adjacent said tab,
rotating said shaft assembly and said housing,
sensing the relative positions of the portions of the distributor shaft assembly, and
applying impacts to said impact-receiving means to move said pin means against said tab to bend the tab to the desired position. I
2. The process of claim 1 comprising sensing the amount of centrifugal advance photoelectrically by reflecting light off a reflecting means located on said distributor shaft assembly.
3. The process of claim 2 in which said directly rotatable portion of the distributor shaft assembly is a lower portion and tion to said lower portion to determine the amount of centrifu gal advance.
4. The process of claim 3 in which said distributor shaft assembly contains a first tab controlling the amount of centrifugal advance at low rotational speeds and a second tab for adjusting the amount of centrifugal advance at higher rotational speeds, said process comprising rotating said shaft assembly at a low set speed and adjusting the amount of centrifugal advance at said low speed by bending said first tab, and sequentially rotating said shaft at a-higher speed and adjusting the amount of centrifugal advance at said higher speed by bending said second tab.
5. The process of claim 4 comprising sequentially varying the rotational speed through a predetermined speed range including both .of said set speeds and displaying visually the amount of centrifugal advance at each speed of said speed range.-
6. A mechanism for adjusting a tab controlling the amount of centrifugal advance of an ignition distributor having means for. rotating a distributor shaft assembly containing a base plate, at least one pivotahle counterweight mounted on said base plate, spring means determining the amount of movemechanism comprising:
ment of said counterweight under the influence of centrifugal a housing mounted on said shaft assembly for rotation with said base plate,
pin means within said housing positioned adjacent said bendable tab,
impact-receiving means at the top of said housing on the rotational axis of said shaft assembly, and
trolling'the amount of advance at different rotational speeds comprising a second pin means within said housing positioned adjacent said bendable tab, a second impact-receiving means at the top of said housing, said second impact-receiving means being concentric with the first impact-receiving means, and impact-transmitting members within said housing for transmitting impacts from said second impact receiving means to said second pin means.
10. A process for bending into position a tab controlling the impact transmitting members within said housing for t an l0 amount of centrifugal advance in an ignition distributor committing impacts to said pin means to move the pin means into contact with said tab and exert a bending force on said tab.
7. The mechanism of claim 6 in which said distributor shaft assembly includes an upper portion rotatable by said counterweight relative to' said base plate so the position of said upper portion relative. to said base plate represents the amount of centrifugal advance at any rotational speed of said shaft assembly, said mechanism comprising hammer means positioned above said impact-receiving means for applying impacts to said impact-receiving means, photoelectric means for reflecting a light beam from a reflecting means on said upper portion, and electronic means for determining the timing of a signal from said photoelectric means relative to a signal representative of said base plate, said electronic means generating a signal for actuating said hammer means when said timing varies from a predetermined value.
8. The mechanism of claim 7 comprising a reset pin for bending said tab in a direction opposite to the direction of bending by said pin means.
9. The mechanism of claim 8 for adjusting the centrifugal advance of a distributor shaft assembly having two tabs conprising:
mounting a housing on a rotatable distributor shaft assembly containing said tab, said distributor shaft assembly including a first portion and a second portion movable relative to said first portion by centrifugal means, said centrifugal means responding to shaft assembly rotation to produce centrifugal advance of said second portion relative to said first'portion, said housing including an impact-receiving means located concentrically with the rotational axis of said shaft assembly, and a pin means contacted by said impact receiving means, said pin means positioned adjacent said tab,
rotating said shaft assembly and said housing,
sensing the centrifugal advance of the second portion, and
applying impacts to said impact'receiving means to move said pinmeans against said tab to bend the tab to the desired position.
11. The process of claim 10 comprising sensing the amount of centrifugal advance photoelectrically by reflecting light off a reflecting means located on said second portion of the distributor shaft assembly.