US3652011A - Elapsed time recorder - Google Patents

Abstract

An instrument incorporates a stop clock which records the time that elapses between the start of turning of a shaft in a specified direction and the completion of a predetermined number of revolutions in that direction. The clock is started by a ratchet and pawl device so that movement in the reverse direction does not start the clock, and the predetermining counter which may be, for example, a friction member bearing on a screw thread has a starting point which can be locked, as desired to alter the predetermined number of revolutions. The stopping point is always the same so that the predetermining counter in effect counts down from an adjustable start. The instrument is primarily intended for measuring the time for an automobile to cover a fixed distance from a standing start by a simple attachment to a road wheel. The ratchet and pawl feature allows the vehicle to be moved (e.g., for accurate positioning on a starting line) without resetting the timer by using the reverse gear.

Description

United States Patent 1 Mar. 28, 1972 West [54] ELAPSED TIME RECORDER [72] Inventor: Glyn West, 30 Leopold Drive, Sarnia, On-

tario, Canada [22] Filed: Feb. 19, 1969 [21] Appl. No.: 800,443

[30] Foreign Application Priority Data Mar. 1, 1968 Canada ..013,730

[52] US. Cl ..235/l04, 58/152 E, 73/488 51 rm. Cl ..G07c 1/00 [58] Field of Search ..58/229, 345,145, 6, 7,- 145 A, 58/152 E; 235/104,?3/488, 489

[56] References Cited UNITED STATES PATENTS 785,515 3/1905 McMurtry ..235/104 903,793 11/1908 Shipman ..235/104 1,116,282 11/1914 l-Iornig ..235/104- 1. 3,125,884 3/1964 Davies "73/514 FOREIGN PATENTS OR APPLICATIONS 32l,556 11/1929 Great Britain ..235/104 Primary Examiner-James J. Gill Attorney-Stevens, Davis, Miller & Mosher [5 7] ABSTRACT An instrument incorporates a stop clock which records the time that elapses between the start of turning of a shaft in a specified direction and the completion of a predetermined number of revolutions in that direction. The clock is started by a ratchet and pawl device so that movement in the reverse direction does not start the clock, and the predetermining counter which may be, for example, a friction member bearing on a screw thread has a starting point which can be locked, as desired to alter the predetermined number of revolutions. The stopping point is always the same so that the predetermining counter in effect counts down from an adjustable start.

using the reverse gear.

7 Claims, 7 Drawing Figures P'ATENTEDMRze I912 3,652,011

sum 1 OF 4 In venior G l yn Ves+ 3/ WM W P'ATENTinmza 1972 SHEET 2 OF 4 Invenor I Glyn We -lmew PATENTED MAR 2 8 I972 3. 6 52.01 1 sumama H66 Invenior Glyn Wesi PATENTEDMAR28 I972 SHEET u 0F 4 invenor Yn Wes?! Hikam eys This invention relates to elapsed time recorders generally; more particularly this invention is concerned with measuring the time taken for a shaft to perform a predetermined number of revolutions.

In a preferred embodiment of this invention, the apparatus is adapted to measure the time taken by an automobile-to travel over a predetermined distance from a standing start by an instrument and a drive that are easily installed.

In the prior art such devices for the more limited embodiment have required what is termed a fifth wheel which is a trailing wheel behind the vehicle; and such devices usually rely on the inertia of mercury in an electrical switch to start the operation of a timing device at the initial acceleration of the vehicle. While the operation of the fifth wheel has been known for a long time for various vehicle testing purposes, a device for measuring the time to cover a given distance is disclosed in US. Pat. No. 3,125,884 issued Mar. 24, 1964.

I have found that the disadvantages of the prior art elapsed time meters may be overcome by providing a ratchet means on a shaft which rotates at a speed proportional to that of the shaft to be timed; and the pawl means associated with the rachet means starts to move when the shaft begins to rotate in the direction in which timing is desired; this movement starts a timing clock. However, rotation of the shaft in the other direction does not move the pawl means and in that case the clock is not started. The clock runs and the revolutions of the shaft in the desired direction are counted until both clock and counter are stopped simultaneously.

In a preferred embodiment the revolution counter is a device which includes a screw thread integral with the shaft and a spring biased level which releasably engages the screw thread and stops the timing clock mechanically after a predetermined number of revolutions has been completed.

This enables the timing device to be a compact assembly; furthermore, since it relies on rotational movement and not acceleration, the assembly may be used for timing 'a predetermined number of revolutions in applications other than vehicles; another feature which will appear later is that the device may be made completely independent of electricity supply; and therefore the device being portable, is very easily installed or removed.

In the more limited application in the road vehicle the timing device is mounted within the cockpit of the car and driven by means of a flexible drive from a specially adapted grease cap on a front wheel. As is well known, odometers, or distance recorders, are inaccurate when driven by the rear wheels of a car; this inaccuracy is slight for sedan cars, trucks and the like in which the odometer drive is conventionally taken from the output side of the transmission. However, in racing vehicles the slip of the rear wheels leads to gross and altogether unacceptable inaccuracies in distance measurement which has lead to the use of the fifth wheel. This is in the nature of an appendix to the vehicle, and being more or less exposed, has obvious disadvantages. I

I have found that this fifth wheel" may be completely eliminated by the provision of a special drive from the front wheel. This consists of a front wheel grease cap with an adaptor to take the inner driving portion of the flexible cable of the type commonly termed a speedometer drive cable, the outer non-rotating sheath of the cable at the grease cap end being a rigid curved pipe or tube of such a radius as to substantially clear the road wheel or tire and suitably directed by the grease cap adapter. After the point at which the wheel or tire has been cleared the outer non-rotating sheath is the conventional flexible sheath and may be coupled to the elapsed time recorder or a speedometer or other instrument adapted to take a speedometer drive cable.

In the drawings which illustrate an embodiment of the invention;

FIG. 1 shows an exploded view of an elapsed time meter instrument;

FIG. 2 shows a perspective view of that part of the mechanism comprising the movable operating bar and its pawl cooperating with the ratchet on the shaft;

FIG. 3 shows a perspective scrap view of the sub-assembly for urging the movable operating bar so that the pawl engages the ratchet;

FIG. 4 shows a diagrammatic representation of the instrument in a ready to start position;

FIGS. 5 and 6 are similar diagrams of the working portions of the instrument in the running position and at the end of the run respectively;

FIG. 7 shows the details of a drive from a front wheel of an automobile.

' The assembly of the instrument and the interaction of the various parts will be understood best by reference to FIG. 1 which shows a back plate 2 on which the main components are assembled. Front plate 4 is parallel to the back plate and is mounted thereon by means of columns 6. A timing clock 8 having a hand making 1 revolution in seconds and another hand making 1 revolution every second, the latter reading on a dial calibrated in one one-hundredth of a second enables times to be determined accurately. The balance wheel 10 of the timing clock is exposed for reasons explained below and the clock is provided 'with a knob not shown for resetting the hands to zero. A hole 12 in the front plate 4 enables the dial of the clock, 8, to be read.

A shaft 14, having an integral screw thread 16 and a ratchet wheel 18 is rotatably mounted in bearings in pillars 20, 22 which project from back plate 2. These pillars may advantageously incorporate dowels 24, 26 which register in holes 28, 30 to locate front plate 4 relative to the back plate 2.

This threaded shaft is driven at the speed of the shaft which it is desired to time. As shown, a union 32 to receive a flexible speedometer type drive is mounted on block 34 of back plate 2; shaft 14 reaches through pillar 20 and block 34 to accept the squared end of the rotatable inner core of the flexible drive.

The ratchet wheel 18 of the shaft engages a pawl 38 which is mounted on operating bar 40 by screw 42 as illustrated at FIG. 2. This mounting also incorporates a pawl biasing spring 44. The operating bar 40 is stable at two discrete positions; in an upper position it prevents operation of the clock by means of a resilient member 46 which bears gently on the balance wheel 10; in a lower position the resilient member 46 is out of engagement and will permit the clock to run. It will be understood that in the upper position, the pawl 38 has an arcuate rotational freedom relative to the operating bar 40 and spring 44 maintains the pawl in non-driving contact with ratchet wheel 18, when the shaft 14 is rotating in an anticlockwise direction, considered looking along the threaded shaft with the ratchet wheel furthest away from the viewer.

The operating bar, as can be seen best from FIG. 2 incorporate two slots 48, 50 by means of which it is slidably mounted through screws 52, 54 in block 56 of back plate 2.

-The operating bar 40 is normally urged towards the upper position by slide bias spring 58 as illustrated in FIG. 3. However, when the shaft 14 begins to rotate clockwise (observing the rotational convention described above) the pawl 38 operates in driving engagement with the ratchet and moves the operating bar to the lower position. In order to maintain the operating bar in the lower position, the bar 40 is provided with a catch 60 which engages with a latch 62 which is biased by latch spring 64. The latch 62 is reset for subsequent operations by pushbutton 66; this has a tripping flange 68 which disengages the latch 62 from the catch 60 and allows the operat ing bar to resume the upper position. A pushbutton spring, 70, normally holds the tripping flange 68 off latch 62.

A lever 72, which projects through front plate 4, has a bight 74; this bight incorporates a rudimentary thread form which is maintained in contact with screw thread 16 of shaft 14 by means of lever bias spring 76; when the shaft rotates clockwise this lever travels along the slot 78 in front plate 4 from right to left when considered as looking on front plate 4 towards the back plate 2. It will be understood that link 80, moving guide bar 82 and fixed guide bar 84 are conveniences for mounting lever 72 with easy disengagement from thread 16. It will also be observed that if the shaft rotates in an anticlockwise direction when the lever is at the right hand end the bias spring is weak enough to allow the screw thread of the lever bight 74 to jump the shaft threads, 16, without damage to either.

A washer 86, set screw 88 and T-nut (not shown) are located at any predetermined point in slot 78 as shown and form an adjustment whereby a predetermined number of revolutions or distance run (within the range of the thread) may be timed; this starting position is adjustable without disturbing the mechanism for starting the clock. It will be understood that any scale (not shown) to read distance or revolutions run must be attached to the washer 86 and be movable therewith along the slot.

The mechanism for stopping the clock at the termination of the run or the predetermined number of revolutions consists of a reduced diameter 90 in the shaft 14 below the level of the threads, the length and location of the diameter reduction being such as to allow the lever 72 to drop into the recess 92 of the slot 78 in the front plate 4. When lever 72 falls into the reduced diameter 90 and the corresponding front plate recess 92 under the action of lever bias spring 76 it turns bell crank lever 94 about pin 96. This pin is fitted to the back of front plate 4, and also accommodates bell crank bias spring 98 which retains the bell crank in its clockwise position; a stop (not shown) is provided for the bell crank to prevent the bell crank bias spring 98 affecting the lever bight screw thread (74-16) engagement; otherwise bias spring 98 would oppose the action of lever bias spring 76.

It will be seen, from a consideration of FIGS. 2 and 4, that in the normal position the bell crank lever is in its clockwise position and does not affect the timing clock; nor does it affect lever bias spring 76 as it is below the level of slot 78. When the lever 72 reaches the end of the thread it drops into the recess 92 in front plate 4 and turns the bell crank in an anticlockwise sense about its pins 96, anticlockwise again being considered when looking on front plate 4 towards back plate 2. Resilient member 100 then gently engages the balance wheel and stops the clock.

The operation of the timing device as embodied in the drawings may already be evident from the description of the functions of the various parts of the instrument. However, to ensure a complete understanding, the operation will be described from the users point of view below.

The number of revolutions of the shaft or wheel (depending on the application) must first be determined. In the case of a racing car to be timed over one-fourth mile, the overall diameter of the road wheel is measured in feet and the circumference divided into 1320 which is the number of feet in onefourth mile. Thus a 30-inch-diameter wheel will require 1320/(2 V2 Xrr) revolutions to accomplish one-fourth mile 168 revolutions The number of threads per inch of the screw thread 16 will either be available or easily measured. Assuming a thread cut at 80 turns per inch lever 72 must travel 168/80 inches, i.e., 2.10 inches.

With the lever 72 snug against the end of the thread in undercut 90 measure 2.10 inches along slot 78 from the right hand side of the lever and move washer 86 so that it prevents the lever 72 from moving beyond this point. Secure washer 86 in position by screw 88.

Press reset button 66. This releases latch 62 and allows operating bar 40 to move to its upper position and prevents the timing clock from starting because resilient member 46 bears on the balance wheel 10.

Wind up, (or energize if electrically driven) the time clock, and reset the hands to zero. Move the lever 72 against washer 86. The instrument will then be ready to run as shown by the position of levers in FIG. 4.

The car may be reversed to the starting position without affecting the instrument; by virtue of the pawl and ratchet action, 18, 38, the clock is not started and spring 76 allows lever bight threads 74 to ride over shaft threads 16. in the event of inadvertent forward motion, the instrument must be stopped by pressing reset button 66, resetting the clock hands to zero and returning the lever 72 to washer 86.

While running, the position of the components is shown in FIG. 5. 0n starting forward motion, the first fraction of a revolution engages the pawl 38 driving the operating bar 40 to its lower position, thus moving resilient member 46 from the balance wheel 10 and allowing the clock to start. The clock shows that at the instant of illustration, approximately half the time has elapsed, which for constant acceleration would correspond to one-fourth of the distance covered by the road wheels and consequently lever 72.

This movement of clock and lever 72 continues until the lever reaches the shaft undercut 90, when the lever drops into slot recess 92 to establish the component position shown in FIG. 6. The lever is no longer conveyed along the slot 78 and in dropping into the recess turns bell crank lever 94 so that resilient member bears against the balance wheel and stops the clock. Even though the car continues on and the shaft 14 continues to turn, the clock cannot start until the unit is reset as described above.

It will be evident from the foregoing that many changes can be made in the embodiment described. For instance and without limitation, operating bar 40 may be biased by means of a ball spring and detents to be stable at either upper or lower position, but not between then; and other equivalent biasing mechanisms may be used. The reset device may then be an extension of the lower end of the operating bar to be pressed upward for resetting.

Similarly, it is not essential for the shaft to have an undercut as the lever 72 can be arranged to close a switch which operates a relay having a resilient member to stop the balance wheel; continued turning would merely cause the threads in lever bight 74 to jump shaft threads 16 as explained before. Alternatively, such a relay could stop the current to the timing clock which may be electrically driven. Such electrical alternatives would, of course, necessitate electrical connections and therefore mechanical stopping devices are preferred. Moreover, it will be apparent on consideration that lever 72 is not essential although it is highly preferred as being both easily resettable and as an indicator of distance run, therefore the lever 72 and the screw thread 16 are essentially a combination for counting the number of turns of the shaft 14, the washer 86, screw 88 and T-nut adding predetermined feature.

Therefore, other methods of counting the number of revolutions may be used; for example, a counter of the type which gives a signal after a selected number of impulses may be operated by an unthreaded shaft and the signal can be used to stop the timing clock. Such counters are readily available and, as they are standard catalogue items called Predetermining Counters, they need not be described in detail. Also, it will be evident that the shaft 14 may be driven through gearing to allow coarser threads or altered ranges to be used.

It will be evident that resilient members 46 and 100 are essentially devices to transmit commands from the mechanism to the timer. For laboratory type electrical stopclocks driven by alternating current these resilient members would be replaced by micro switches.

Alternatively, a clockwork wound stopwatch may be used. Such watches are available with a wide variety of types of actuation; some have all three operations (that is start, stop and reset) controlled by successively depressing the crown; others have a side button to reset or to stop the watch; others have a serrated slide for controlling one or more operations. Although the many different types of stop latch actuation make it impracticable to illustrate a preferred embodiment it will be obvious to those skilled in the art that the motions of bar 40 and the bell crank lever 94 (or the equivalent actuating means on a predetermining counter) can be used to start, stop and reset a stop watch. The maximum accuracy of one-tenth second obtainable in such a stopwatch will be equal to that of most pawl and ratchet operations.

The flexible drive aspect of this invention which eliminates the fifth wheel will now be described with reference to FIG. 7; this shows a largely conventional cable with a stationary flexible outer sheath 110 and a rotating inner flexible shaft having conventional squared drive ends 112, 114. The termination at end 112 where the drive is screwed into the timing device or other speedometer odometer instrument is entirely conventional. However, at the other end, the flexible outer sheath, 110, terminates considerably before the drive end in a fitting, 116, soldered to the end cap 118. Such a fitting is a standard hardware or plumbers item known as a tube fitting. The remainder of the outer sheath is a rigid inch diameter copper tube 120, which incorporates a right angle curve as shown in FIG. 7. In the embodiment illustrated, a compression type tube fitting has been used, so that nut 122 sealingly couples tube 120 to fitting 116 by means of ferrule 124.

when the drive is ready for installation, the squared drive end 114 projects from the end of tube 120 remote from fitting l 16 and is coupled directly to a square hole in special adaptor 126 welded to a standard automobile front wheel grease cap 128. This brings the remote end of tube 120 into bearing relationship about the adaptor 126, and by cantilever action, holds the other end out from the wheel and prevents it fouling. The squared drive end 114 is retained in the adaptor by a quick release device such as a cotter pin 130. Such an arrangement enables the drive to be easily removed and is preferable to changing grease caps with the attendant risk of getting dirt in the wheel bearings.

Although it has not been specifically explained above, it will be evident to those familiar with automobiles that the provision of the rigid curved tube 120 prevents the flexible cable fouling the tire when the wheels are being turned to effect direction change of the car. Furthermore, the length of the curve or right angle bend will be lessened if the tube is coplanar with turning axis of the wheel, and increased if the tube is in a plane at right angles to the axes both of rotation and turning.

It will also be obvious that various modifications may be made to this part of the apparatus also. The rigid curved tube may be soldered directly to the cable although this may make insertion of the inner core more difficult; the rigid curved tube does not have to extend equivalent to the road wheel outer radius as the flexible portion cannot bend sharply to foul the wheel.

It will be understood that the flexible drive as shown will require mounting on the left front wheel to drive a shaft.l4 (having a conventional right hand thread 16) in the correct direction. However, either wheel may be used by a second union for a speedometer drive (similar to union 32) at the other end of the shaft, that is, mounted on pillar 22.

While there has been shown and described what is at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention as defined by the appended claims.

I claim. 1. An elapsed time recorder instrument suitable for timing a number of revolutions in a predetermined direction of rotation, comprising ashaft,

a timing clock,

a ratchet wheel coupled to said shaft and rotatable in either direction,

a pawl means having a movable mounting, said pawl means being associated with said ratchet wheel,

a movable connecting means connected to said clock mechanism and adapted to start the clock, said pawl means being mounted on said movable connecting means and adapted to move the movable connecting means when the shaft starts to rotate in the predetermined direction but not otherwise, and

an adjustable predetermining counter means coupled to said shaft, said predetermining counter having an operating means actuated after a predetermined number of shaft revolutions, I said operating means being connected to said timing clock so that the operation stops said clock.

2. An instrument as claimed in claim 1 in which said predetennining counter means comprises a shaft having a screw thread and a lever engageable with the screw thread for travel through a length proportional to the number of revolutions to be timed, and

a spring biasing the lever onto the thread so that the lever will move along the thread unless positively constrained.

3. An instrument as claimed in claim 2 in which the adjustment of the predetermining counter comprises:

an adjustable stop positioned so as to determine the commencement of the travel of said lever engageable with the screw thread.

4. An instrument as claimed in claim 1 in which the means connecting said pawl means to said clock is a bar and in which said pawl is mounted on said bar and further comprising:

biasing means to provide a first and second stable position for said bar so that the clock is started upon movement of said bar from one stable position to the second, the subsequent operation of the clock being independent of the second position of said bar.

5. An instrument as claimed in claim 2 in which:

the rotatable shaft having a screw thread has an unthreaded portion at the end corresponding with the termination of the number of revolutions to be timed, the unthreaded portion having a diameter substantially reduced from the root diameter of the thread for a length sufficient to allow said screw thread engaging lever to drop through a substantial distance and further comprising:

a clock stopping lever adapted to engage both the timing device and the screw thread engaging lever when the screw thread engaging lever drops, so as to stop the.timing device.

6. An instrument as claimed in claim 2 in which the adjustable predetermining counter means has a count adjustment means which is adjustable at the beginning of the count, without affecting the ability to allow movement in the reverse direction.

7. An instrument as claimed in claim 1 which is suitable for use with a reversible road vehicle and further comprising:

a flexible cable suitable for connecting said shaft to a vehicle weight bearing wheel hub.

Claims (7)

1. An elapsed time recorder instrument suitable for timing a number of revolutions in a predetermined direction of rotation, comprising a shaft, a timing clock, a ratchet wheel coupled to said shaft and rotatable in either direction, a pawl means having a movable mounting, said pawl means being associated with said ratchet wheel, a movable connecting means connected to said clock mechanism and adapted to start the clock, said pawl means being mounted on said movable connecting means and adapted to move the movable connecting means when the shaft starts to rotate in the predetermined direction but not otherwise, and an adjustable predetermining counter means coupled to said shaft, said predetermining counter having an operating means actuated after a predetermined number of shaft revolutions, said operating means being connected to said timing clock so that the operation stops said clock.

2. An instrument as claimed in claim 1 in which said predetermining counter means comprises a shaft having a screw thread and a lever engageable with the screw thread for travel through a length proportional to the number of revolutions to be timed, and a spring biasing the lever onto the thread so that the lever will move along the thread unless positively constrained.

3. An instrument as claimed in claim 2 in which the adjustment of the predetermining counter comprises: an adjustable stop positioned so as to determine the commencement of the travel of said lever engageable with the screw thread.

4. An instrument as claimed in claim 1 in which the means connecting said pawl means to said clock is a bar and in which said pawl is mounted on said bar and further comprising: biasing means to provide a first and second stable position for said bar so that the clock is started upon movement of said bar from one stable position to the second, the subsequent operation of the clock being independent of the second position of said bar.

5. An instrument as claimed in claim 2 in which: the rotatable shaft having a screw thread has an unthreaded portion at the end corresponding with the termination of the number of revolutions to be timed, the unthreaded portion having a diameter substantially reduced from the root diameter of the thread for a length sufficient to allow said screw thread engaging lever to drop tHrough a substantial distance and further comprising: a clock stopping lever adapted to engage both the timing device and the screw thread engaging lever when the screw thread engaging lever drops, so as to stop the timing device.

6. An instrument as claimed in claim 2 in which the adjustable predetermining counter means has a count adjustment means which is adjustable at the beginning of the count, without affecting the ability to allow movement in the reverse direction.

7. An instrument as claimed in claim 1 which is suitable for use with a reversible road vehicle and further comprising: a flexible cable suitable for connecting said shaft to a vehicle weight bearing wheel hub.

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