US3747848A

US3747848A - Incremental rotational drive

Info

Publication number: US3747848A
Application number: US00202266A
Authority: US
Inventors: D Stothart
Original assignee: Gulf Research and Development Co
Current assignee: Chevron USA Inc
Priority date: 1971-11-26
Filing date: 1971-11-26
Publication date: 1973-07-24
Anticipated expiration: 1990-07-24

Abstract

Means for changing a continuous rotation at a first shaft into an incremental or stepping rotation of a second shaft with some predetermined ratio of length of increment of rotation of the second shaft per rotation of the first shaft, utilizing a scrollshaped cam to drive a racheting arrangement, whereby any partial rotation of the first shaft is inherently stored as a position of the racheting arrangement on the scroll-shaped cam. The motion of the second shaft, directly or via transmission means, can be used to drive some operating member.

Description

United States .Patent- 1 Stothart July 24,1973

[54] INCREMENTAL ROTATIONAL DRIVE 3,344,986 10/1967 Stasenko et 235/94 R 1 1 II I 1 i David Stow-H, Cheswwk, 3,328,523. 3/1323 ifciafiffifii 232/ 512? [73] Assi gnee: GulfResearch & Development 3390,06) 1/1970 f 74/142 companyipittsburgh Pa. 3,504,206 3/1970 Fntsch 74/126 X 1 Filed: w 2 1971 Primary Examiner-Richard B. Wilkinson 21 A L N b: 266 Assistant Examiner-U. Weldon [1 1 pp 0 v Attorney-Meyer Neishloss et al.

[52] US. Cl. 235/94 R, 235/91 R, 235/92 C 57 I ABSTRACT 2; g 'i' 2 Means for changing a continuous rotation at a first 1 e o 235/92 shaft into an incremental or stepping rotation of a second shaft with some predetermined ratio of length of increment of rotation of the second shaft per rotation [56] References Cited of the first shaft, utilizing a scroll-shaped cam to drive UNITED STATES PATENTS a racheting arrangement, whereby any partial rotation 2,712,899 7/ 19 55 Krtous 235/91 R of the first shaft is inherently stored as a position of the 2,714,049 7/1955 Gel'malm- 235/94 R racheting arrangement on the scroll-shaped cam. The v 1;; ls-iood Mal/5:4 motion of the second shaft, directly or via transmission lmmons 3,154,672 10/1964 'Larkin 235/94 R x means can be used to some operatmg member 3,295,756 1/1967 Kelch et al 235/91 R X 14 Claims, 4 Drawing Figures mam-mums SNEU 1 BF 2 Pmmwm w 3.747. 848

sum 2 or 2 FIG 4 FIG 2 I I INCREMENTAL ROTATIONAL DRIVE This application -is related to U. S. Pat. No. 3,598,283; entitled Gasoline Pump Computer, by Ronald L. Krutz and Thomas J. Villella, and also is more specifically related to the divisional application of said patent, co-pending application Ser. No. 120,647, filed March 3, I971 entitled Pulsing Mechanism, by said Krutz and Villella, now U. S. Pat. No. 3,686,507. This application is also related to co-pending Ser. No. 202,446 filed on the same day as this application, entitled Digital Encoder, Especially for Mechanical Counters," by the same inventor as this application. All of the above related inventions are assigned to the same assignee as the present invention.

Generally, the present invention provides means to transform a continuous or an intermittently continuous rotational motion into an incremental or stepping rotational motion. That is, the motion of one shaft which rotates continously is changed in accordance with the teaching of the invention into rotation of a second shaft which is incremental, i.e., sporadic or stepping with the angular length of each" increment of motion of the sec.- ond shaft corresponding to some fixed amount of rotation of the first shaft. Thus, it is necessary to effectually store'the motion of the first shaft in the apparatus of the invention until that first shaft has moved an amount corresponding,'as per the ratio between the shafts, to one increment of motion of the second shaft, and to thereupon index or move the second shaft one whole increment all at once. The rotation of the first shaft may then continue, either constantly or intermittently since the storing feature of the invention accommodates either kind ofmotion equally well, until another incremental motion of the second shaft is required, and so forth. Y

The above identified inventions constitute the environment in which the present invention was developed. In the .above identified parent patent, the circuit requires a predetermined number of electrical pulses per unit volume of gasoline passing through the pump, and the invention can be used to produce 100 electrical pulses per gallon. 100 pulses per gallon was chosen in conjunction with the nature of the parent circuit because the number 100 is decimal and thus easily handled, and produces a commercially acceptable accuracy. The above identified divisional application is directed to an improved pulsing mechanism. The present invention is a conceptually different incremental drive, particularly suited for use as a pulsing mechanism. As

will appear in more detail below, the present invention could be used to produce virtually any number of pulses, or, more generally, any ratio of incremental movements at a second shaft per full rotation of a first shaft.

The present invention is a wholly mechanical means of operating the active member in a circuit, for example, the reed switch in the gasoline pump environment identified above. Because it is wholly mechanical, the invention operates virtually error-free, i.e., no rotation is lost, no spurious pulses are created and no pulses are lost. Because'of this improved accuracy, a gallon of gasoline need not be made to correspondto the relatively large I00 pulses, but instead the invention can be added into existing gasoline pump dispensing computers at a location in such computers wherein each revolution of some shaft, which would be the first or input I which:

shaft, would correspond to a larger quantity of money or of volume dispensed, e.g., l revolution per dime or per dollar'or l revolution per gallon or per tenth of a gallon.

The above identifed divisional application, in summary, comprises an interlock of two electrical reed switches each operated by a separate magnet, both of which magnets are mounted on a single magnet mounting block, and arranged mechanically and electrically in such a way that the one active pulse producing reed switch is enabled by a second reed switch and its associ- I ated magnet for only a small part of a full rotation of the mounting block. Thus the time, as a percentage of a full rotation of the mounting block, during which the system is susceptible to externally induced error, such as spurious pulses created by the electrical systems of vehicles in the area, is reduced. However, in that system, there is still a possibility that the parts could stop in aposition at which the active reed switch is susceptible to externally induced errors. The present invention improves upon that system by mounting a magnet at the output end of the inventions incremental drive so that the reed switch which is operatively cooperable with that magnet does not see" a continuous motion of the magnet at all but rather sees" only quick l80 motions of the magnet, thereby virtually totally eliminating the time, absolutely and not merely as a percentage of rotation, during which the reed switch is not directly under the influence of itsoperating magnet and thus susceptible to externally induced errors.

The above and other advantages of the invention will be pointed out or will become evident in the following detailed description and claims, and in the accompanying drawingalso forming a part of the disclosure, in

FIG. 1 is an end elevational view of an embodiment of the invention as it might be mounted in a gasoline pump computer; v

FIG. 2 is a right side cross-sectional view takenon line 2-2 of FIG. 1; i

FIG. 3 is a left side elevational view taken on line 3-3 of FIG. 1; and' FIG. 4 is a view similar to FIG. 3 showing a second embodiment of the invention.

Referring nowin detail to the drawing, there is shown in FIG. 1 a pair of walls 10 and 12, which may comprise two internal walls-in a conventional gasoline pump me chanical computer, or walls added thereto for mounting the invention, or equivalent means in any other environment in which the invention may be used. A first shaft 14 comprises the input shaft which is to drive the incremental drive mechanism 16 of the present invention. The output or second shaft 18 is to be driven incrementally or sporadically and in some ratio of angular length or increment per rotation of the first shaft 14, all in a manner and for reasonsthat will be developed below. The angular length of rotation of the second 3. Means 25, comprising a conventional suitably anchored flat spring type of pawl, is provided to prevent wheel 24 from turning backwards.

Rotatably mounted in wall 12 is a magnet shaft 26 which carries a pinion 28 which meshes with the gear 22 and which carries a bar magnet 30 at its outer free end, see FIG. 2. A magnet is used at 30 in the embodiment being described, but any other sort of operating member for other applications could be used at the output of the invention. A reed switch 32, of the type set forth in more detail in the two above identified related patent specifications, is mounted on the wall closely spaced to but not touching and operatively cooperable with the magnet 30. The

parts

30 and 32 herein correspond to the

parts

42 and 44 respectively in both said specifications.

In regard to the terms first and second shafts as used herein, it will be appreciated that in this specific embodiment the shaft 26 is in fact the output shaft since it carries the magnet 30 which operates the switch 32. However, more generally, the shaft 18 could be thought of as the second or the output shaft in that it will be driven incrementally and, depending upon the ratios required, could be used directly. Transmission means comprising the gear and

pinion

22 and 28 are provided as a matter of convenience in order to be able to provide more teeth on rachet wheel 24 while producing a relatively large angular rotation of

magnet

30, 180, in response to each rotation of input shaft 14, as will appear below.

The invention comprises means to change the intermittent continuous or continuous rotational motion of shaft 14 into incremental rotational motions of shaft 18. To this end, there is provided an operating bar assembly 34 which comprises a main bar member 36 which is provided with a lower end contactor portion 38 and a rachet operating pawl portion 40. If desired for other applications, suitable anti-friction means such as a yoke mounted roller, could be provided in place of the simple contactor shown. A tension spring 42 is provided between an anchor 44 fixed to wall 10 and a spring pin 46 mounted on bar 36. Spring 42 is disposed at a suitable angle to both bias the contactor 38 against the operating surface of scroll shaped cam 20 and to urge pawl portion 40 into engagement with the teeth of rachet wheel 24. A pair of closely spaced guide pins 48 constrain the motion of bar 36 and a second pair of guide pins 50 defines the limits of motion of pawl portion 40 towards and away from shaft 18. Other guide means, not shown, will be provided to constrain bar assembly 34 to its plane of operation as indicated in FIG. 1. Thus, bar 36 may be thought of as floating in that it has no firm connection anywhere. Pins 48 serve as pivots. The pins 50 are so placed as to stop the bar and to prevent overshoot of the rachet wheel due to inertia.

In the specific embodiment of the invention shown and described,'the shaft 14 was connected to an existing shaft in the mechanical gasoline pump computer such that shaft 14 makes one revolution for each ten cents worth of gasoline dispensed by the pump. Such a shaft, 10 cents per turn, already exists in most conventional pump computers. As shown, rachet 24 has 10 teeth, and the gear 22 and pinion 28 are in a 5 to l ratio. The height 52 of the cam 20, i.e., the change in radius from its largest radius to its smallest radius is substantially equal to the length along each flat 54 of each tooth of rachet wheel 24. Thus, for each revolution of the shaft 14 carrying the cam 20 the bar 36 will be raised by the height of one tooth of wheel 24. The spring 42 moves the pawl 40 from one tooth to the next, and when the cam 20 rotates through the full revolution, the contactor 38 will fall off the high part of the cam and onto the low part of the cam to thereby incrementally move shaft 18, with the aid of spring 42, one-tenth of a revolution per revolution of shaft 14. The cam is undercut slightly, i.e., the height 52 is tilted off the radial, so that the contactor will fall off the cam all at once, and not hang up on the height. This feature is most clearly shown in FIG. 4.

Thus, shaft 18 will move incrementally rotationally in a ratio of l to 10 as shaft 14 moves continuously. Of course, as is evident, this rotation of shaft 18 could be used directly in some other application. In the specific embodiment being described, with reference to FIG. 2, it is desired to incrementally rotate pinion 28 and hence magnet 30 180 for each full rotation of shaft 14. The five to one gear ratio between the

parts

22 and 28 accomplish this goal. The ratio chain is one turn at 14 produces one-tenth of a turn at 18 which produces onehalf of a turn at 26. Thus, the reed switch 32 is operated, in a sure and positive'manner, at the rate of one cycle or one operation per 10 cents worth of gasoline dispensed.

It can be seen that, by the provision of a suitable number of teeth on the rachet 24, each such suitable number corresponding to a suitable height 52 of the operating cam 20, various different ratios between the

shafts

14 and 18 can be achieved. For large changes, on the order of 10:1 or more, it is preferred to use gearing at shaft 14. That is, an output of an increment of angular rotation of any desired length can be made to correspond to a rotation of the input. Various other schemes to further increase the versatility of the invention will present themselves to those skilled in the art. For example, arrangements such as transmission means 22 and 28 can change the ratio; a double or triple or more lobed operating cam in lieu of the cam 20 could be provided; or gearing elewhere. 4

In the above-identified related inventions, the pulsing mechanism is used to produce pulses per gallon, and these pulses are counted to totalize the money value dispensed and the volume dispensed. One of the reasons that 100 pulses per gallon were used rather than 1 pulse per penny or 1 pulse per gallon, is that that circuitry is susceptible to gaining or losing 1 or 2 pulses, and since the relatively large number of 100 pulses per gallon is used, such a relatively minor loss or gain makes an insignificant error. The present invention, wholly mechanical, has virtually no capability of losing a pulse, short of physical breakage of a part, and thus very low ratios of 1 pulse per dime or per penny or per gallon or per large fraction of a gallon can be safely used. Generally, the output can be made to correspond to any unit value of money or of volume. Modifications to the computing circuitry driven by the pulses from reed switch 32 to accommodate such changes are easily within the expertise of those skilled in the art.

The advantage of effectual storage of a partial rotation or motion less than a full turn of shaft 14 is inherent in the mechanical arrangement of the parts as shown. For example, if switch 32 were in a circuit which was maintaining a running total of gallons dispensed, and shaft 14 rotated once per gallon, then any fraction of a gallon dispensed, as between sales to different customers, is inherently stored in the rotational operation of the cam 20 with respect to contactor member 38. Of course, the apparatus, in this example, would have to be such that it did not reset between sales.

Referring now to FIG. 4, there is'shown a second embodiment 16a of the invention. Insofar as possible, parts in FIG. 4 the same as or closely corresponding to parts in FIG. 3 are indicated by the same reference numeral followed by a. The essential difference in the two embodiments l6 and 16a is that the preferred embodiment 16 may be thought of as using a floating operating bar whereas the second embodiment 16a is built around a pivoted operating bar. The floating bar is more versatile in regard'to ease of placement into existing computers. It lends itself readily to workingaround obstacles already existing in the pump computer. Thus, bar 36a is pvioted to wall 10a by a pin 56. A tension spring 58 is locatedbetween a fixed anchor 60 and a spring pin 62 on the bar 36a to urge the bar to the right towards the cam 20a. The shafts 14a and 180 are in a different relationship to each other than the corresponding parts in FIG. 3, but such modifications may be dictated by the particular apparatus being worked with or in any case may be easily adjusted by .those skilledin the art. Intermediate its ends, bar 36a carries a pawl 64 which cooperates with the scroll shaped active surface of the cam 20a to pivot bar 36a on pin 56 between stops 48a. At its upper end, bar 36a carries a pivot 66 to which is mounted an operating finger 68 which cooperates with the teeth on the rachet wheel 24a. A spring 70 is arranged between the parts 36a and 68 to urge the finger 68 into cooperative operation with the rachet wheel 24a.

While the invention has been described in detail above, it is to be understood that this detailed description is by way of example only, and the protection granted is to be limited only within the spirit of the invention and the scope of the following claims.

I claim:

1. Apparatus for converting a continuous or intermittently continuous rotation of a first shaft into an incremental rotation of a second shaft at some predetermined ratio of angular rotation per increment of the second shaft per full rotation of the first shaft, comprising cam means mounted on said first shaft, lever means operated by said cam means, a rachet wheel operated by said lever means, spring means for urging said lever means into contact with both said cam means and said rachet wheel, said rachet wheel having a predetermined number of teeth, transmission means operatively cooperable with said rachet wheel, and a second shaft driven by said transmission means, an operating member mounted on said second shaft, said operating member comprises a bar magnet, and an electrical reed switch operatively cooperable with said bar magnet, wherein said cam means comprises a scroll shaped opcrating surface for cooperation with said lever means having a height between its smallest radius portion and its largest radius portion substantially equal to the length of a flat of a tooth on said rachet wheel, and wherein said cam height isundercut slightly to cause said lever means to move readily from said largest radius portion to said smallest radius portion.

2. The combination of claim 1, wherein said rachet wheel is formed with 10 teeth and wherein said transmission means between said rachet wheel and said magnet is in the ratio of five to one, whereby said sec- 0nd shaft and said bar magnet turn for each full turn of said first shaft.

3. The combination of claim 2, wherein said transmission means comprises a gear connected to said rachet wheel and a pinion on said second shaft'in engagement with said gear.

4. The combination of claim I, said lever means comprising a floating bar having a pawl portion cooperable with said rachet wheel and constrained to motion between said cam means and said rachet wheel by said spring means and a plurality of guide pins.

5. The combination of claim 1, wherein said lever' portion-for urging said finger portion into contact with said-rachet wheel.

6. The combination of claim 1, wherein said first shaft is operatively cooperable with a portion of a mechanical gasoline dispensing pump computer, and wherein said first shaft rotates at the rate of l revolution per some unit money value of gasoline dispensed by said pump, and wherein said reed switch is in a circuit for totalizing the money value of gasoline dispensed by saidpump;

7. The combination of claim 6, wherein said first shaft is a shaft of said computer which rotates at the rate of l revolution per ten cents of money value of gasoline dispensed.

8. The combination of claim 1, wherein said first shaft is operatively cooperable with a portion of a mechanical gasoline dispensing pump computer, and

wherein said first shaft rotates at the rate of l revolution per some unit volume of gasoline dispensed by said pump, and wherein said reed switch is in a circuit for totalizing the volume of gasoline dispensed by said pump.

9. The combination of claim 8, wherein said first shaft is a shaft of said mechanical computer which rotates at the rate of l revolution per gallon of gasoline dispensed by said pump.

10. A method of operating an electrical reed switch from a first shaft at the rate of one cycle of the reed switch per rotation of the first shaft comprising the steps of operating rachet means by 'cam means mounted on said first shaft, operating transmission means by said rachet means, mounting a bar magnet on the output end of said transmission means in operative cooperation with' said reed switch, and selecting the proportions of said cam means and said rachet means and the ratio of said transmission means such that said magnet will turn 180 for each full rotation of said first shaft and only turns said 180 at the completion of each full rotation of said first shaft, and such that motions of said first shaft less than a full revolution are stored, as positions of said rachet means on said cam means.

11. Apparatus for converting a continuous or intermittently continuous rotation of a first shaft into an incremental rotation of a second shaft at some predetermined ratio of angular rotation per increment of the second shaft per-full rotation of the first shaft, comprising cam means mounted on said first shaft, lever means operated by said cam means, a rachet wheel operated. by said lever means, spring means for urging said lever means into contact with both said cam means and said rachet wheel, said rachet wheel having a predetermined number of teeth, transmission means-operatively cooperable with said rachet wheel, a second shaft driven by said transmission means, a bar magnet mounted on said second shaft, an electrical reed switch operatively cooperable with said bar magnet, wherein said first shaft is operatively cooperable with a portion of a mechanical gasoline dispensing pump computer, and wherein said first shaft rotates atthe rate of l revolution per some unit money 'value of gasoline dispensed by said pump, and wherein said reed switch is in a circuit for totalizing the money value of gasoline dispensed by said pump.

12. The combination of claim 11, wherein said first shaft is a shaft of said computer which rotates at the rate of l revolution per 10 cents of money value of gasoline dispensed.

13. Apparatus for converting a continuous or intermittently continuous rotation of a first shaft into an incremental rotation of a second shaft at some predetermined ratio of angluar rotation per increment of the second shaft per full rotation of the first shaft, comprising cam means mounted on said first shaft, lever means operated by said cam means, a rachet wheel operated by said lever means, spring means for urging said lever means into contact with both said cam means and said rachet wheel, said rachet wheel having a predetermined number of teeth, transmission means operatively cooperable with said rachet wheel, a second shaft driven by said transmission means, a bar magnet mounted on said second shaft, an electrical reed switch operatively cooperable with said bar magnet, wherein said first shaft is operatively cooperable with a portion of a mechanical gasoline dispensing pump computer, and wherein said first shaft rotates at the rate of one revolution per some unit volume of gasoline dispensed by said pump, and wherein said reed switch is in a circuit for totalizing the volume of gasoline dispensed by said pump.

14. The combination of claim 13, wherein said first shaft is a shaft of said mechanical computer which rotates at the rateof 1 revolution per gallon of gasoline dispensed by said pump.

Claims

1. Apparatus for converting a continuous or intermittently continuous rotation of a first shaft into an incremental rotation of a second shaft at some predetermined ratio of angular rotation per increment of the second shaft per full rotation of the first shaft, comprising cam means mounted on said first shaft, lever means operated by said cam means, a rachet wheel operated by said lever means, spring means for urging said lever means into contact with both said cam means and said rachet wheel, said rachet wheel having a predetermined number of teeth, transmission means operatively cooperable with said rachet wheel, and a second shaft driven by said transmission means, an operating member mounted on said second shaft, said operating member comprises a bar magnet, and an electrical reed switch operatively cooperable with said bar magnet, wherein said cam means comprises a scroll shaped operating surface for cooperation with said lever means having a height between its smallest radius portion and its largest radius portion substantially equal to the length of a flat of a tooth on said rachet wheel, and wherein said cam height is undercut slightly to cause said lever means to move readily from said largest radius portion to said smallest radius portion.

2. The combination of claim 1, wherein said rachet wheel is formed with 10 teeth and wherein said transmission means between said rachet wheel and said magnet is in the ratio of five to one, whereby said second shaft and said bar magnet turn 180* for each full turn of said first shaft.

3. The combination of claim 2, wherein said transmission means comprises a gear connected to said rachet wheel and a pinion on said second shaft in engagement with said gear.

4. The combination of claim 1, said lever means comprising a floating bar having a pawl portion cooperable with said rachet wheel and constrained to motion between said cam means and said rachet wheel by said spring means and a plurality of guide pins.

5. The combination of claim 1, wherein said lever means comprises a bar pivoted at one end and having a pawl portion cooperable with said cam means and a finger portion cooperable with said rachet wheel, and second spring means between said bar and said finger portion fOr urging said finger portion into contact with said rachet wheel.

6. The combination of claim 1, wherein said first shaft is operatively cooperable with a portion of a mechanical gasoline dispensing pump computer, and wherein said first shaft rotates at the rate of 1 revolution per some unit money value of gasoline dispensed by said pump, and wherein said reed switch is in a circuit for totalizing the money value of gasoline dispensed by said pump.

7. The combination of claim 6, wherein said first shaft is a shaft of said computer which rotates at the rate of 1 revolution per ten cents of money value of gasoline dispensed.

8. The combination of claim 1, wherein said first shaft is operatively cooperable with a portion of a mechanical gasoline dispensing pump computer, and wherein said first shaft rotates at the rate of 1 revolution per some unit volume of gasoline dispensed by said pump, and wherein said reed switch is in a circuit for totalizing the volume of gasoline dispensed by said pump.

9. The combination of claim 8, wherein said first shaft is a shaft of said mechanical computer which rotates at the rate of 1 revolution per gallon of gasoline dispensed by said pump.

10. A method of operating an electrical reed switch from a first shaft at the rate of one cycle of the reed switch per rotation of the first shaft comprising the steps of operating rachet means by cam means mounted on said first shaft, operating transmission means by said rachet means, mounting a bar magnet on the output end of said transmission means in operative cooperation with said reed switch, and selecting the proportions of said cam means and said rachet means and the ratio of said transmission means such that said magnet will turn 180* for each full rotation of said first shaft and only turns said 180* at the completion of each full rotation of said first shaft, and such that motions of said first shaft less than a full revolution are stored as positions of said rachet means on said cam means.

11. Apparatus for converting a continuous or intermittently continuous rotation of a first shaft into an incremental rotation of a second shaft at some predetermined ratio of angular rotation per increment of the second shaft per full rotation of the first shaft, comprising cam means mounted on said first shaft, lever means operated by said cam means, a rachet wheel operated by said lever means, spring means for urging said lever means into contact with both said cam means and said rachet wheel, said rachet wheel having a predetermined number of teeth, transmission means operatively cooperable with said rachet wheel, a second shaft driven by said transmission means, a bar magnet mounted on said second shaft, an electrical reed switch operatively cooperable with said bar magnet, wherein said first shaft is operatively cooperable with a portion of a mechanical gasoline dispensing pump computer, and wherein said first shaft rotates at the rate of 1 revolution per some unit money value of gasoline dispensed by said pump, and wherein said reed switch is in a circuit for totalizing the money value of gasoline dispensed by said pump.

12. The combination of claim 11, wherein said first shaft is a shaft of said computer which rotates at the rate of 1 revolution per 10 cents of money value of gasoline dispensed.

14. The combination of claim 13, wherein said first shaft is a shaft of said mechanical computer which rotates at the rate of 1 revolution per gallon of gasoline dispensed by said pump.