GB1565595A - Device for obtaining the correct indicating position of a value indicating roller - Google Patents

Description

(54) DEVICE FOR OBTAINING THE CORRECT INDICATING POSITION OF A VALUE INDICATING ROLLER (71) We, KIENZLE APPARATE GmbH, a German Body Corporate of Villingen Schwenningen, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The invention relates to a device for obtaining the correct indicating position of a value indicating roller in a counter driven by a long gear train, when the counter drive is suddenly stopped, the device being loaded in driving direction to supply a constantly effective resetting torque on the indicating roller in an opposite direction via a brake.

It is known that with counters driven at high speed indicating errors are to be observed which are due to the fact that the indicating rollers-which frequently have a very big diameter so that the moving masses are rather high-throw over the actual indicating position when the drive is suddenly stopped by the stored kinetic energy being released. When there are several gears or other connecting elements between the actual measuring system and the indicating roller the total gear play between the individual gears is added in the driving direction when the driving input is suddenly stopped. This means that the actual indicating roller will be able to move through an additional angle which represents the overthrow error sometimes amounting to several units of the amount to be measured at the indicating rollers.This error is practically unavoidable with any mechanical gearing connections since toothed wheel gearings can only work with optimal effect when a certain gear play is involved.

In order to maintain the indicating error at least within admissable limits it has also already been tried to brake the driving gear by means of a friction brake. This device, however, has the big disadvantage that for higher driving speeds with heavy indicating rollers the braking force has to be increased.

Too much braking on the indicating roller means an inadmissable load on the counter drive.

In the German utility model 1 885 075 a device is shown by means of which the disadvantages of the usual braking can be avoided and a mistake in the indication due to an overswinging of the indicating roller when the drive is suddenly stopped, can be corrected or compensated for. To this end a braking disk is mounted for rotation together with the indicating roller which braking disk cooperates with a braking bracket rotatably mounted on the shaft of the braking disk. From an arm laterally projecting from the bracket mounted on the braking disk shaft the actual braking part or rather the braking jaw is attached by means of an adjustable screw. By means of a pressure spring the braking jaw is pressed radially onto the peripheral plane of the braking disk thereby producing a corresponding friction.A spiral spring influences the braking bracket in a direction opposite to the driving direction and serves to retract the indicating roller through the same angular range which it has been overthrow. The correct indicating position has been reached when all the gear play has been taken away in a direction opposite to the driving direction.

The disadvantages of the known device are to be seen in that due to the arrangement of the braking bracket and due to the spring cooperating with the braking jaw there is a unilateral load on the braking disk so that braking bracket may be tilted on the braking disk shaft. This means after a very short time that the bracket works itself into the drive shaft so that completely different friction and braking moments naturally result therefrom. Also, a high quality material for the mounting bushings has not shown to be satisfactory remedy.

The steadily changing quality of the bearing also modifies the effect of the braking pressure from the braking jaw on the braking disk. The braking pressure is no longer radially applied and as a consequenec there of there is no correct guiding and no correct engagement of the braking jaws with the friction disk. To avoid such malfunctioning it is necessary to exchange the damaged parts which, however, is only possible by a rather expensive mounting and demounting of the whole braking disk shaft.

The present invention preferably provides a braking means which is simple in production and operation which has a better braking quality and which can be designed for subsequent mounting on an old braking disc element without demounting the braking disk shaft and by means of which any unilateral load on the shaft with which it cooperates is avoided, According to the present invention, there is provided a device for obtaining the correct indicating position of a value indicating roller driven by gearing in a counter having a braking disk coupled to the counter drive, the device comprising braking and resetting means adapted for resilient loading during rotation of the roller by frictional engagement with the disk so as to effect partial rotation of the indicating roller in the reverse direction to the normal direction of drive when the drive to the indicating roller is stopped, wherein the braking and resetting means includes an annular or part an- nular jacket carrying friction means to engage with the disk, the jacket being resiliently radially expandable to enable it to be drawn over the braking disc and be retained thereon. Since the braking jacket is elastic it can be mounted on the braking disk without using special tools. Preferably the jacket is part annular so that a piece of the jacket is left open and therefore the braking jacket can be subsequently added to already readily mounted counters with- out any expensive mounting work. This quality, of course, is of essential importance when the parts have to be exchanged in servicing operations so that expensive demounting and mounting work can be avoided.An exactly concentrical and coaxial mounting of the braking jacket with respect to the braking disk is achieved in that there are three braking jaws inserted into the braking jacket which are regularly distributed over the periphery of the braking jacket, which braking jaws are positively kept in a stable position. The braking pressure to be exerted, which may be by pretensioning the braking jacket or by an additional force, is applied uniformly and radially via all braking jaws on the braking disk so that the friction is uniformly distributed.

Since the braking jaws are uniformly distributed about the braking disc the counter driving shaft is loaded by braking or frictional forces of even amount in forward and backward direction.

A constructional embodiment of the present invention will now be described by way of example, with reference to the accompanying drawings, wherein Fig. 1 is a perspective view of a drive shaft for a counter with a braking and resetting device Fig. 2 is a view of the braking element, Fig. 3 is a section through the braking element.

As may be seen from Fig. 1 the drive shaft 1 drives a multiposition counter of which the indicating roller 2 only has been shown.

The indicating roller 2 is the lowest decade of the counter which is continuously driven by an analogue number of revolutions from a measuring or computing device. To this purpose the indicating roller 2 is provided with a toothed rim 3 and is in driving engagement with a toothed wheel 4 which may be coupled by means of an axially effective clutch 5 with the drive shaft 1. It is the purpose of the clutch to release the counter to be reset so that the indicating rollers 2 return to "0" which may be effected by means of a heart cam resetting device attached to the indicating roller 2. The drive shaft 1 itself is monunted in plate 6 of a counter frame at its both ends. The drive shaft 1 is driven by means of a bevel gear 7 connected thereto which is in engagement with another bevel gear, not shown.As in most applications there are a number of intermediate gears connecting the bevel gear 7 with the actual input gear producing a number of revolutions in accordance with the measured values which gears serve to adapt the number of revolutions to the indicating means and which may also serve to adjust recorded volumes to a certain price and so on. Due to this train of gears it is possible that the indicating roller, when the measuring device is suddenly stopped, moves beyond the actual value to be indicated which angular distance is maximally the sum of all the gear play in the gearing. In order to avoid this erroneous indication in the indicating means a braking disk 8 is fixed to the drive shaft 1 for the indicating roller 2 which disk is provided with a peripheral cylindrical plane 9 as a braking surface. The braking disk 8 cooperates with a braking and resetting element which consists essentially of a one piece circular braking jacket 11 having a radially extending lever arm 12. At a hook 16 on this lever arm 12 a spiral spring 13 is applied which delivers a continuously effective resetting torque the spring 13 being fastened on a projection 14 at a crossing traverse 15 between the two plates 6. The lever 12 also cooperates with two stops 17 which serve to limit the angular displacement of the braking jacket 11 which stops are also arranged on the traverse 15.

The braking jacket is made as a part annulus of deformable material so that there is an opening which allows the braking jacket to be drawn over the braking disk.

Between the braking jacket 11 and the peripheral surface 9 of the braking disk 8 there are arranged frictional pads or braking jaws 18 equally distributed over the circumference and of equal quality which jaws apart from producing the necessary friction moment serve to coaxially mount the braking and resetting element 11 on the shaft 1.

To take up the braking jaws 18 the internal surface of the braking jacket 11 is provided with chambers 19 in even distribution so that due to a pretension resulting from its shape the braking jacket and/or an additional auxiliary force produce an evenly distributed braking pressure on the braking disk 8. An advantageous effect is achieved when three braking jaws 18 are evenly distributed over the circumference as may be seen from Fig. 1. As the braking jaws 18 are arranged symmetrically to the lever arm 12 the same frictional conditions substantially are met when the drive shaft 1 is driven in either forward or backward direction. To take up the braking jaws the chambers 19 are like boxes so that the braking jaws must only be loosely inserted therein and are then positively retained without any additional fastening means just by the radial pressure applied on the braking disk 8.

For laterally guiding the braking jacket 11 on the braking disk 8 the braking jacket 11 is provided with radially arranged lugs 20 in the same arrangement as the chambers 19. These lugs simultaneously serve to reinforce those sectors of the braking jacket which carry the braking jaws, thereby supporting the jaws and making sure that their bending radius is maintained and that they rest on the circumferential plane 9 with as much surface as possible. The chambers 19 for the braking jaws 18 are connected to each other by means of elastically deformable arc-shaped links 21. The link 21 which would have to be thought opposite to the lever arm 12 has been omitted. At the free ends 22, 23 hooks 24 are arranged which if so required serve to hang-in a tangentially effective spiral spring 25 or another auxiliary force applying a corresponding draw.

Through the action of the spiral spring 25 the braking jaws apply an esseneially radial pressure on the braking disk surface 9. The braking pressure produces a frictional moment which can be so adjusted that when the driving shaft 1 is moved in recording direction, for example in Fig. 1 in clockwise direction, the resetting torque spring motor is loaded. When the measuring device is suddenly stopped the indicating roller 2 and the whole gear train arranged in between will not be stopped immediately due to the inertia of the moved masses.The value which had been attained at the moment when the measuring device was stopped, however, will be reattained in that the continuously stored resetting torque in the spring becomes effective in that all the gear play which had been transmitted to the indicating device by overthrowing is turned out again causing partial rotation of the indicating roller in the reverse direction to the normal direction of drive. Thus the braking and resetting element 10 serves a friction clutch.

WHAT WE CLAIM IS:- 1. A device for obtaining the correct indicating position of a value indicating roller driven by gearing in a counter having a braking disk coupled to the counter drive, the device comprising braking and resetting means adapted for resilient loading during rotation of the roller by frictional engagement with the disk so as to effect partial rotation of the indicating roller in the reverse direction to the normal direction of drive when the drive to the indicating roller is stopped, wherein the braking and resetting means includes an annular or part annular jacket carrying friction means to engage with the disk, the jacket being resiliently radially expandable to enable it to be drawn over the braking disc and be retained thereon.

2. A drive according to Claim 1, wherein the braking jacket is part annular and is provided with several chambers evenly distributed over its periphery to take up frictional elements for engaging the disk so that due to a pretensioning in the braking jacket and/or a contracting auxiliary force the braking pressure applied is evenly distributed over the periphery of the braking disk.

3. A device according to Claims 1 and 2, wherein the braking jacket has three chambers in arc-shaped arrangement for the frictional elements.

4. A device according to Claim 2, wherein the chambers are in the form of boxes to positively take up the loosely insertable frictional elements.

5. A device according to Claims 1, 2 and 3, wherein the braking jacket is provided with lugs turned from its circumference radially inward and arranged along the chambers for the braking elements which lugs surround the braking disk.

6. A device according to Claim 3, wherein the three chambers for the braking elements are connected with each other via two arcshaped elastically deformable links while one arc part closing the circle is omitted.

7. A device according to Claims 1, 2 and 6, wherein at the free ends of the brak

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. annulus of deformable material so that there is an opening which allows the braking jacket to be drawn over the braking disk. Between the braking jacket 11 and the peripheral surface 9 of the braking disk 8 there are arranged frictional pads or braking jaws 18 equally distributed over the circumference and of equal quality which jaws apart from producing the necessary friction moment serve to coaxially mount the braking and resetting element 11 on the shaft 1. To take up the braking jaws 18 the internal surface of the braking jacket 11 is provided with chambers 19 in even distribution so that due to a pretension resulting from its shape the braking jacket and/or an additional auxiliary force produce an evenly distributed braking pressure on the braking disk 8. An advantageous effect is achieved when three braking jaws 18 are evenly distributed over the circumference as may be seen from Fig. 1. As the braking jaws 18 are arranged symmetrically to the lever arm 12 the same frictional conditions substantially are met when the drive shaft 1 is driven in either forward or backward direction. To take up the braking jaws the chambers 19 are like boxes so that the braking jaws must only be loosely inserted therein and are then positively retained without any additional fastening means just by the radial pressure applied on the braking disk 8. For laterally guiding the braking jacket 11 on the braking disk 8 the braking jacket 11 is provided with radially arranged lugs 20 in the same arrangement as the chambers 19. These lugs simultaneously serve to reinforce those sectors of the braking jacket which carry the braking jaws, thereby supporting the jaws and making sure that their bending radius is maintained and that they rest on the circumferential plane 9 with as much surface as possible. The chambers 19 for the braking jaws 18 are connected to each other by means of elastically deformable arc-shaped links 21. The link 21 which would have to be thought opposite to the lever arm 12 has been omitted. At the free ends 22, 23 hooks 24 are arranged which if so required serve to hang-in a tangentially effective spiral spring 25 or another auxiliary force applying a corresponding draw. Through the action of the spiral spring 25 the braking jaws apply an esseneially radial pressure on the braking disk surface 9. The braking pressure produces a frictional moment which can be so adjusted that when the driving shaft 1 is moved in recording direction, for example in Fig. 1 in clockwise direction, the resetting torque spring motor is loaded. When the measuring device is suddenly stopped the indicating roller 2 and the whole gear train arranged in between will not be stopped immediately due to the inertia of the moved masses.The value which had been attained at the moment when the measuring device was stopped, however, will be reattained in that the continuously stored resetting torque in the spring becomes effective in that all the gear play which had been transmitted to the indicating device by overthrowing is turned out again causing partial rotation of the indicating roller in the reverse direction to the normal direction of drive. Thus the braking and resetting element 10 serves a friction clutch. WHAT WE CLAIM IS:-

1. A device for obtaining the correct indicating position of a value indicating roller driven by gearing in a counter having a braking disk coupled to the counter drive, the device comprising braking and resetting means adapted for resilient loading during rotation of the roller by frictional engagement with the disk so as to effect partial rotation of the indicating roller in the reverse direction to the normal direction of drive when the drive to the indicating roller is stopped, wherein the braking and resetting means includes an annular or part annular jacket carrying friction means to engage with the disk, the jacket being resiliently radially expandable to enable it to be drawn over the braking disc and be retained thereon.

2. A drive according to Claim 1, wherein the braking jacket is part annular and is provided with several chambers evenly distributed over its periphery to take up frictional elements for engaging the disk so that due to a pretensioning in the braking jacket and/or a contracting auxiliary force the braking pressure applied is evenly distributed over the periphery of the braking disk.

3. A device according to Claims 1 and 2, wherein the braking jacket has three chambers in arc-shaped arrangement for the frictional elements.

4. A device according to Claim 2, wherein the chambers are in the form of boxes to positively take up the loosely insertable frictional elements.

5. A device according to Claims 1, 2 and 3, wherein the braking jacket is provided with lugs turned from its circumference radially inward and arranged along the chambers for the braking elements which lugs surround the braking disk.

6. A device according to Claim 3, wherein the three chambers for the braking elements are connected with each other via two arcshaped elastically deformable links while one arc part closing the circle is omitted.

7. A device according to Claims 1, 2 and 6, wherein at the free ends of the brak

ing jacket there are hooks between which a tangentially effective spiral spring may be applied.

8. A device according to Claims 1 and 2, wherein diametrically to the missing part of the braking jacket there is a lever arm projecting radially from the braking jacket at which lever arm a force is effective supplying a resetting torque to rotate the roller in the reverse direction which lever arm can move between two fixed stops limiting the angle of movement of the braking jacket.

9. A device according to Claims 1, 2 and 8, wherein the lever arm is arranged symmetrically to the frictional elements thereby achieving a uniform frictional moment in the two driving directions.

10. A device substantially as described herein with reference to and as illustrated by the accompanying drawings.

11. A device as claimed in Claim 1, substantially as hereinbefore described.