US3716185A - Taximeter drive with constant time drive speed - Google Patents

Abstract

THE FARE REPRESENTING SHAFT OF A TAXIMETER IS DRIVEN BY ONE-WAY CLUTCHES FROM DISTANCE AND TIME DRIVE MEANS. WHILE THE DISTANCE DRIVE MEANS DRIVE THE SHAFT AT VARYING SPEEDS, THE TIME DRIVE MEANS HAS A MOTOR WHICH ROTATES AT A CONTINUOUSLY CONSTANT SPEED SO THAT UNDESIRED SIMULTANEOUS DRIVING OF THE SHAFT BY BOTH DRIVE MEANS, CAN TAKE PLACE ONLY MOMENTARILY WHEN, DURING DRIVING OF THE SHAFT BY THE DISTANCE DRIVE MEANS, THE VARYING SPEED OF THE SHAFT IS MOMENTARILY EQUAL TO THE CONSTANT SPEED AT WHICH THE TIME DRIVE MEANS DRIVES THE SHAFT.

D R A W I N G

Description

Feb. 13, 1973 H. KELCH Erm. 35716.185

TAXIMETER DRIVE wITH CONSTANT TIME DRIVE SPEED Filed April 30. 1971 2 Sheets-Shet 1 MV1-Wrap Fen-13,1913 .EmH mL 1,116,135

' TAXIMETER Dmym WITH CONSTANT TIME DRIVE SPEED med April so. '19717 j zfsmets-sheet a' United States Patent O 3,716,185 TAXIMETER DRIVE WITH CONSTANT TIME DRIVE SPEED Heinz Kelch, Buchenherg, and Eduard Schuh, Villingen, Germany, assignors to Kienzle Apparate GmbH, Villingen, Germany Filed Apr. 30, 1971, Ser. No. 138,955 Claims priority, application Germany, May 2, 1970, P 21 598.9 Int. Cl. C07b 13/00 U.S. Cl. 235-- R 5 Claims ABSTRACT OF THE DISCLOSURE The fare representing shaft of ya taximeter is driven by one-way clutches from distance and time drive means. While the distance drive means drive the shaft at varying speeds, the time drive means has a motor which rotates at a continuously constant speed so that undesired simultaneous driving of the shaft by both drive means, can take place only momentarily when, during driving of the shaft by the distance drive means, the varying speed of the shaft is momentarily equal to the constant speed at which the time drive means drives the shaft.

BACKGROUND `OF THE INVENTION The present invention is concerned with an improvement of taximeters of the type in which overrunning oneway clutches, controlled by the speed of the car and by the time, drive a common shaft whose position represents the fare charged to a customer.

The distance travelled by the taxicab, and the Waiting times are added and determines the indicated fare. The distance Idrive is connected by reduction gearing and a oneway clutch with the common shaft, and shifts the indicating means to the next unit :according to the selected rate or tariff by which the price for the unit of distance travelled is determined. In the same manner, the time drive means act through transmission means and `a one-way clutch on the common shaft, and cause indications of yan increased fare `depending on the time elapsed. Due to the provision of the overrunning one-Way clutches, only the faster motion of the two motions transmitted from the distance drive and from the time drive, acts on the cornmon shaft to turn the same to the next following fare indicating position. The rates for travelled distance, and for waiting time periods, are in a certain relation to each other so that fbelow a certain limit speed, at a standstill or slow movement of the taxicab, only the time rate is bein-g charged. Above the limit speed, only travelled distances are chargedand indicated. The limit speed is determined in accordance with local conditions, and depends on the rates charged for travelling and waiting. Accordingly, a taximeter must switch at the limit speed from a condition at which the common shaft is driven by the distance drive, to a condition at which the common shaft is driven from the time drive, Iand must assume the higher speed of the two speeds which would be caused by the distance drive or bythe time drive, respectively.

Conventional taximeters rely on clockworks for the time drive means, or an equivalent pulsating time drive with an electromagnet is used.

The clockworks used las timing devices for taximeters, are conventional clockworks with an escapement mechanism so that an intermittent pulsating motion is transmitted to the common shaft. Consequently, the time drive has a motion phase during which the common shaft is driven, followed by an interval in which no drive motion is transmitted to the common shaft. During the interval in which no motion is transmitted from the time drive,

3,716,185 Patented Feb. 13, 1973 "ice the distance drive will drive the common shaft, even fbelow the limit speed, which falsifies the result represented by the common shaft. It is possible that, below the limit speed, the common shaft causes an indication of time elapsed, and distance travelled, which is incorrect, since below the limit speed, the indication only represent the elapsed time.

Similar considerations are true for speeds above the limit speed, because the amplitude peaks of the timing pulses extend into the upper speed region where only the -distance drive means should rbe effective. During a peak amplitude of the pulse of thetiming drive means, a phase of the timing pulse is added to the speed of the distance drive means, which has an accelerating effect so that the speed at which the common shaft is driven is too high, and not only based on the distance travelled by the taxicab, as intended.

Furthermore, when escapement regulators are used for the clockwork, a change of the rate charged for certain time unit, causes the problem to maintain an exact timing operation of the timing drive, while the driving force is maintained constant. A change of the time drive rate requires `also an adjustment of the transmission ratio between the escapement mechanism and the common shaft, which causes also a variation of the force acting on the escapement wheel. The consequence is that the regulating device has a tendency to lag or to recoil.

The German Auslegeschrift 1,206,188 discloses another taximeter drive arrangement. \An electromagnet is fed with the constant series of pulses, and is used as time time drive means connected with the common shaft. This time drives also intermittently drives the common shaft,f

and the result is that in the entire range, the driving movement of the time drive is faster during the pulse phase than the rotary motion which is applied by the distance drive to the common shaft, depending on the speed of travel of the taxicab. The result is again an addition of time and distance values during the entire range of operations. In order to prevent this faulty operation, or for compensating errors due to this faulty operation, an additional lost-motion coupling -has been provided between the timing means and the common shaft. During movement of the taxicab, when the distance drive is effective, a slotted disc gains during intervals between motions of the time drive for a certain distance. If a faster driving motion pulse occurs, a pin moves in the slot of the slotted disc in a lost-motion movement, and only a part of the pulse motion has a driving effect on the common shaft. The construction has the disadvantage that it is difficult to tind the correct length of the slot, particularly if a number of different rates of the taximeter is provided. The lost motion coupling can compensate the unavoidable errors only approximately.

It has been proposed to use a synchronous motor for the timing drive, but the rotor of the synchronous motor is substantially a stepping motor operating at the frequency of the voltage source, and the current has a sinusoidal fluctuation which permits the transition from distance drive to time drive, and vice versa, over the entire range of the amplitude of the sinusoidal fluctuation, which also results in incorrect fare indications, which cannot be corrected in any manner.

SUMMARY OF THE INVENTION It is one object of the invention to overcome the disadvantages and faulty operation of taximeters according to the prior art, and to provide a taximeter drive.

which accurately responds to the distance drive or to the time drive.

Another object of the invention is to provide a taximeter drive in which the .fare representing shaft is driven by the distance drive above a continuously constant limit speed, and by the time drive at the limit constant speed, and can only momentarily be driven by the time and distance drive simultaneously.

Another object of the invention is to momentarily shift a taximeter drive from operation by the timing drive to operation by the distance drive, and vice versa.

With these objects in view, the present invention provides a motor rotating continuously at constant rotary speed, and acting through a transmission and a one-way clutch on the fare representing shaft of the taximeter at a constant speed, as long as the speed of the common shaft is equal, or below, a predetermined speed.

In the preferred embodiment of the invention, the timing drive means include a direct current motor, which has no commutator, and is electronically regulated to a constant speed.

A taximeter drive according to the invention comprises a fare indicating shaft; distance drive means including a rst one-way clutch for driving the shaft in one direction at a varying speed depending on the travelled distance; and time drive means including a second oneway clutch for driving the shaft in the same direction, a constant speed motor operating at a continuously constant uniform speed, and transmission means connecting the constant speed motor with the second one-way clutch for rotating the shaft at a predetermined constant speed.

-As a result, the shaft is driven by the distance drive means at varying speeds above the predetermined constant speed by the time drive means at the predetermined speed, and simultaneously by the distance and time drive means only momentarily when the shaft is momentarily driven by the distance drive means at a speed equal to the predetermined constant speed.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specic embodiments when read in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a perspective, partially exploded, view illustrating a taximeter drive according to an embodiment of the invention; and

FIG. 2 is a diagram illustrating graphically the speed of a fare representing shaft of the embodiment of FIG. 1 during control by distance and time drive means.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring first to FIG. 1, a fare representing shaft 1 carries a stepping cam 6 cooperating with the roller 7 mounted on a pivot 8 on a lever 9 which is supported by a pivot 10I for angular movement with a pawl 12 cooperating with a ratchet wheel 13 secured to the shaft 14 of a fare indicating number wheel 15. During each revolution of fare representing shaft 1, ratchet wheel 13 will be shifted one step, and the number wheel 15 will be correspondingly turned a step to represent the next following monetary unit. A spring 11, secured to a stationary point urges lever 9 with roller 8 into engagement with the stepping cam 6.

The fare representing shaft 1 is connected by oneway clutches 2 and 3 with time drive means 4, and distance drive means 5, respectively. While one-way clutch 3 is illustrated in the normal operational position, oneway clutch 2 is illustrated in an exploded condition in which the outer casing member 19, which is secured by a pin to shaft 1, is spaced from the inner gear 1S.

The one-way clutches 2 and 3 are of conventional construction, and permit rotation of shaft 1 only in counterclockwise direction, and in such a manner that the distance drive means 5 and the time drive means 4 do not interfere with each other, and overrunning is possible.

As shown for one-way clutch 2, the cam 16 is secured by screw 17 with a gear 18, and is mounted on shaft 1 for free rotation. A cylindrical cage 19, which is secured by a pin or screw 20 with the fare representing shaft 1, envelops the cam 16 in the assembled condition in which one-way clutch 3 is shown. The clutch is engaged in one direction of rotation when rollers 21, biassed by springs 22, jam in wedge-shaped spaces between the inner surface of the cage 19, and the outer peripheral cam surface of cam 16. When rollers 21 are forced into the narrower portion of the wedge-shaped spaces, a slippage free engagement of the clutch is obtained. Springs 22 are held in position by a spring cage 23. Each gear 18 has a peripheral set of gear teeth, only partially shown. The one-way clutch 3 is constructed in the same manner as the one-way clutch 2.

Gear 18 of one-way clutch 2 meshes with a gear 24 connected by shaft 25 with another gear 26 meshing with a gear 27 secured to shaft 29 which also carries a gear 28 meshing with a gear 30 whose shaft 31 is connected with a worm gear 32 meshing with a worm spindle 33 on the shaft 34 of a motor 35.

Motor 35 is a direct current motor (U.S. Pat. 3,475,- 668) which has no commutator, and whose rotary speed is automatically controlled by an electronic circuit 35a regulator so that the rotor and shaft 34 of motor 35 rotate at an absolutely constant speed which may be selected by adjusting means, and is then automatically maintained by the electronic regulating means. Construction of the motor is not an object of the invention, however, it is required that in accordance with the invention, the rotary speed of motor 35 is absolutely constant and has no fluctuations or variations of any sort.

The distance drive has a flexible shaft 36 which is connected for rotation with a moving part of the taxicab, for example with a wheel. The number of rotations of the wheel, which depends on the distance travelled by the taxicab, is directly transmitted to a transmission 37 whose output shaft 38 drives gear 40 of the one-way clutch 3 by a gear 39, In the transmission 37, the rotary input speed of shaft 36 is transformed at a ratio dependent on the required speed of the fare representing shaft 1 for indicating monetary units on number wheel 15.

Both the time drive means 4 and the distance drive means 5 act through one-way clutches 2 and 3, respectively, on the fare representing shaft 1, and the arrangement is such that shaft 1 is rotated at the greater speed of the two speeds of the time drive means 4 and distance drive 5.

The manner and sequence in which the fare representing shaft 1 is operated either by the time drive means 4 or the distance drive means 5, will be best understood with reference to the diagram of FIG. 2 whose abscissa represents time units, and indicates a time t during which the taxicab is operated. The ordinate represents units of speed, for example revolutions per minute.

The speed of the time drive means 4 transmitted to the gear 18 of the respective one-way clutch 2 is represented by the broken line a, and starts with a short acceleration from the point A to the point B, whereupon the speed of the time drive means is maintained absolutely constant due to the provision of the constant speed motor 35 until at the end of the trip, the motion of the time drive S is stopped between the points O and P.

The second graph b, which is shown in dash and dot lines, represents the speed of rotation of gear 40 of the distance drive means 3. The taximeter is accelerated from the point C to the point D where graph b intersects with graph a, further accelerated to the point E, maintained at constant speed until the point F is reached, reduced in speed until point G is reached, where, for example,

the speed may be maintained constant to the point H, whereupon the speed is again reduced to the point J where the speed is maintained constant at the level of the limit speed BO at which gear 18 of the time drive means operates, whereupon the speed of the gear 40 is further reduced to the speed L, then maintained at the same speed to the point M, and finally reduced to a standstill at the point N.

The full line graph c represents the speed of the fare representing shaft 1. Due to the provision of the oneway clutches Z and 3, shaft 1 rotates at the higher speed of the two speeds transmitted to shaft 1. Consequently, shaft 1 will accelerate between the points A and B due to the action of the time drive means 4, and the effective one-way clutch 2, and then rotate at the constant speed of the time drive means due to the fact that the graph a represents a higher speed in the region BD than the graph b represents in the region C to D.

Since the speed of shaft 1 obtained by the distance drive means between the points D and J is greater than the speed which could be obtained by the time drive means between'the points D and I the speed of the shaft is represented by the graph c along the points D, E, F, G, H, I.

In the region between the point J and the point K, graph c happens to coincide with the corresponding portion of graph a', which means that the distance drive happens to operate at a constant speed, and furthermore at the predetermined limit speed represented by graph a. In this region J, K, both drives are eiective to drive fare representing shaft 1, and both one-way clutches 2 and 3 may be engaged. However, when the speed of the taximeter and ofthe distance drive is further reduced along the points K, L, M, N, so that the distance drive means would drive shaft 1 at a lower speed than the time drive means between'the points K and O, the one-way clutch 3 is disengaged, `and the one-way clutch 2 of the time drive means is effective to operate the fare representing shaft 1 at the limit speed.

Clutch 2 of the time drive means 4 is engaged between the points A and D, and between the points J and P.

Clutch 3 of `the distance drive means is engaged bctween the points D and l, and I, K, respectively. It will be seen that at the point D, one of the one-way clutches is engaged, and the other is released. The shifting of the clutches takes place momentarily so that the time drive means and distance drive means do not operate simul taneously, except in the region .l to K where, entirely coincidentally, the speed of the distance drive means was not only equal to the speed of the time drive means, but also constant for the distance J-K.

The graphs of FIG. 2 clearly show that the time drive operations and the distance drive operations are clearly separated. For example, when the speed of the one-way clutch 3 is slightly higher than the speed of the one-way clutch 2 in the same region G, H, distance drive 5 clearly operates shaft 1 through one-way clutch 3. In the region L-M, where the limit .speed obtained by time drive 4 and one-way clutch 2 is higher than the speed of the gear 40 of the one-way clutch 3, only the time drive 5 rotates shaft 1.

The arrangement of the invention eliminates the difficulties of the prior art in which a pulsating time drive has to be changed to a continuously moving distance drive. This is not lpossible since the varying motion of the distance drive may intersect with the timing pulses during the entire amplitude peak of the same, and render the mutual shifting between two drive components partly elfective during the entire time pulse amplitude. In ac cordance with the prior art, no means are known for compensating faulty measuring due to this cause with the precision at which the apparatus of the invention operates.

-Even the use of a synchronous motor for the time drive means, does not have the advantages of the time drive means of the present invention provided with a motor electronically regulated to a continuous constant speed. This is due to the fact that the sinusoidal variation of the characteristic of the synchronous motor cannot -be completely eliminated, since it is exclusively dependent on the frequency of the voltage source. A synchronous motor used for the timing drive of a taximeter, and particularly used for maintaining a precise shifting between the time drive means and the distance drive means at the point of intersection with the limit speed, is hardly better suited than conventional stepping motors.

The time drive means of the invention provided with the constant speed motor has the advantage that due to a favorable characteristic of the torque, the time units of the entire range of rates are covered, while for the same purpose, mechanical clockworks require several different escapement regulators and mechanical force accumulators, such as a wound up spring.

The motor used in accordance with the invention in the taximeter drive, operates at a very low noise level, and particularly the ticking, unavoidable in a mechanical clockwork, and the noise produced by winding up of the force accumulator, are eliminated. Since the motor drive does not require servicing, the drive of the invention is expected to operate without trouble for a long span of life.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of taximeter time and distance drives differing from the types described above.

While the invention has been illustrated and described as embodied in the time drive means for a taximeter having a constant speed regulated direct current motor, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gistof the present invention that others can by applying current knowledge readily adapt it for various applications with omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this inven- A tion and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims..

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

We claim:

1. Taximeter drive comprising, in combination, a fare indicating shaft; distance drive means including a rst one-way clutch for driving said shaft in one direction at a varying speed depending on the travelled distance; and time drive means including a second one-way clutch for driving said shaft in said one direction, a constant speeld motor, operating at a non-fluctuating continuously constant and uniform speed, and transmission means connecting said constant speed motor with said second oneway clutch for rotating said shaft at a predetermined constant speed in said one direction so that said shaft is driven by said distance drive means at varying speeds above said predetermined constant speed, by said time drive means at said predetermined speed, and simultaneously by said distance and time drive means only momentarily when said shaft is momentarily driven by said distance drive means at a speed equal to said predetermined constant speed.

2. Taximeter drive as claimed in claim 1 wherein said constant speed motor is a direct current motor.

3. Taximeter drive as claimed in claim 1 wherein said motor includes electronic circuit means for maintaining the rotary speed of said motor constant at said predetermined speed.

7 8 4. Taximeter drive as claimed in claim 1 wherein said 3,286,917 11/ 1966 Kelch 23S-30 R constant speed motor is a commutator-less direct current 3,295,756 1/1967 Kelch et al 23S- 30 R motor.

S. Taxirneter drive as claimed in claim 1 wherein said OTHER REFERENCES second one-way clutch includes a first part continuously 5 Fitzgerald, A E' & Higginbotham, D E Basic Elec. rotated at said predetermined constant speed, and a second ical Engineering, McGraw-Hill, 2nd Ed., 1957, pp.

part connected with said shaft. 241, 242

R f C1 d Oberg, E. & Jones, F. D., Machinerys Handbook,

e emes e The Industrial Press, 16th Ed., 1959, p. 2020. UNITED STATES PATENTS 10 2,698,132 12/1954 Pombriand 23S-3o R RICHARD B- WILKINSON Primary Examiner 3,163,357 12/ 1964 Kelch et a1. 23S-30 R S. A. WAL, Assistant Examiner

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