DE1173682B - Precision inclination scale for the continuous weighing of a load that changes over time, registered on a recording device - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Boarding school Kl .: G Ol g

German KL: 42 f - 25/02

Number: 1173 682

File number: St 7841IX c / 42 f

Filing date: February 27, 1954

Opening day: July 9, 1964

The invention relates to a precision inclination balance for continuous use on a recording device registering weighing of a load that changes over time with one carried by the balance beam electrical transmitter element, which at a predetermined deflection of the balance beam over electrical switching devices controls the putting on and off of shift weights.

In normal precision or chemical balances, it is known to have hand-operated devices to be provided for placing and removing weights. Such devices can be cams or similar parts which are arranged on spindles, which can be opened by turning knobs or Slices are operated to add or remove one or more weights to thereby return the balance beam to its inclination range after a load change, the exceeds this range has occurred.

In large weighing devices it is also known to use the movement of the beam to initiate the application or removal of weights; such arrangements, which assume that the balance beam performs a work in the device through its movement, however unsuitable for use with precision balances.

For continuous weighing processes with precision balances two different ways of working have been used so far. The first is the weighing range limited to the area given only by a deflection or a deflection of the bar is. In the second method, the area is expanded by applying a fine chain or is removed, whereby the bar is always returned to its insertion area, after he has reached the predetermined limit of his movement. Both methods have disadvantages, and the first because of the very limited available area and the second because of one continuously operating device this arrangement has the tendency to deflect over an area, which corresponds to the weight of a chain link, and also because the area of such a link Balance can only be obtained with a simultaneous loss of accuracy, since chain weight and Accuracy are related to each other.

With the precision inclination balance, the disadvantages listed above are now avoided by that according to the invention one carried in a known manner by the balance beam and the recording device controlling follow-up device when the limits of the inclination range are reached

Precision inclination balance for continuous,
on a recording device
registering weighing of a timed
changing load

Applicant:

Stanton Instruments Limited, London

Representative:

Dipl.-Ing. H. Görtz, patent attorney,

Frankfurt / M., Schneckenhofstr. 27

Named as inventor:

Frederick Arthur Claridge, Morden, Surrey,

Normal Frank Hinton, Upper Norwood, London, Robert John Whitcroft,

West Norwood, London (Great Britain)

Claimed priority:

Great Britain February 27, 1953 (5592) -

Balance and the limits of the recording device via contacts that put on or off the switching weights. takes off in such a way that the switching weights each switch to that of the previous limit opposite limit of the inclination area and the recording device takes place.

A great advantage of such a scale is that it allows slight changes in weight over time, how they can be measured with a precision balance, e.g. B. the moisture absorption to a substance within a predetermined period of time, without any retroactive effects register, with the balance working as a tilt balance most of the time. If the However, when the balance reaches the upper or lower limit of its inclination range, contact is made a shift weight added or removed, the size of this inclination range between the two limit positions on the one hand and the size of the additional weight on the other hand matched are, so that by adding or removing a weight the scales always from one

409 629/100

Limit position of the inclination area goes into the other. This allows a particularly clear registration.

The principle of the well-known shift weight scales with automatic activation of the weights, whereby the switching on and removal of the weights already with a relatively minor emigration of the Balance from the loading position would have the disadvantage for such continuous weighing that

Fig. 1 is a schematic representation of the whole Systems,

F i g. 2 shows a rear view of the device for applying the weights,

F i g. 3 is a side view of the FIG. 2 device shown,

Fig. 4 is a section along the line IV-IV of Fig. 2,

F i g. 5 is a circuit diagram of the electrical front control mechanism practically continuously in operation for io directions,
to add correspondingly smaller weights or in the case of the arrangement shown in FIG

to take away. the follow-up device consists of a condenser,

There are already scales with tracking devices, an electrode 1 fixed on the balance beam 2 known, the trailing drives feel each one is mounted so that they pound themselves with him usually the position of one moves into a certain position 15, while the other electrode 3 is attached in this way Well-rehearsed scales from a counting or printing is that they are under the action of a servo motor 4 to operate the plant. _ be moved towards or away from electrode 1

Nor is it new to the scales. The electrodes are electrically connected to a beams the movable plates of one connected in an elek- device 5, which reacts to changes in the tric oscillating or bridge circuit lying Kon- 20 capacity responds and the servo motor 4 in such To connect the capacitor and which controls by deflections of the way that with a movement of the balance beam caused changes in the electric bar and electrode 1, electrode 3 Quantities by means of electrical measuring instruments to move away that the capacitance between the electrodes Display or register, with one of the returned to its original value Balance beam controlled tracking device with a 25. The electrode 3 therefore follows the movement of the Recording device is coupled. Because normal bar, and the angular movement of the servo motor wise weighing orders of magnitude more accurate than one is thus proportional to the movement of the weighing bucket-like Determining electrical quantities comes kens. The servo motor is arranged so that it Befür Precision weighing such a method is not actuated in limit switch 6, which, as will be considered below. Furthermore, the required calibration 30 is written there, a device 7 for applying of the instrument by the slightest changes and weights and also the spring of a rain in the electrical resonant circuit, such as B. low registration device 8 drive.

mechanical changes to the capacitor or by the in the F i g. 2, 3 and 4 shown device

Resistance changes due to temperature changes - to apply the weights is on a frame wrestling made worthless. One in this known 35 10 mounted, on which a base plate 11 is attached. Device further disclosed engaging or disengaging. The device includes arms 12 for application Taking weights is said to be by means of polarized re-weights, two of which are groups of four lais take place, which are again provided for inaccuracies poor. Each of these arms is up leads, since such relays by no means a so clearly a fixed shaft 13 articulated behind the have a fixed point of use, as it is for the pre-4 ° base plate 11, namely opposite of opening weighing would be absolutely necessary. openings through which the arms protrude. the

Finally, it is also with weighing devices that the front ends of the arms are provided with hooks 14 knows, provided a follower device for actuating a receptacle of weights, while the Arrange registration device and weight rear ends with sensing elements 15 provided are automatic at a predetermined deflection of 45. The arms are divided by two groups 16.17 To switch on the scales. In such devices is actuated by four cam disks, one each however, the scale cam disk is provided for each arm during the connection process. the locked, while group 16 is rotatably mounted on a spindle 18 in the scales according to the invention the connection and removal of shift weights and the other group on a socket 19 through can be done without the balance being locked 5 ° which the spindle goes through. Any cam disc will. is designed in such a way that when it is rotated it

In the scales according to the invention, the appropriate arm can be raised or dropped, with the Control of the tracking device on different arm in its lowered position the weight, which Wise cause, for example, the one plate is attached to the hook 14, on the balance beam Arrange a capacitor on the balance beam, put 55 on it and in its raised position the weight while the other plate is lifted from the beam by a servomotor. Each group of arms bears is moved away. Here, the weights compared with the servomotor, e.g. B. in the ratio 1: 2: 2: 5, and the group-bound Plate operated in such a way that they are the cam disks arranged with the pen-wise so from the balance beam connected continuously lags, d. that is, formed that with one complete revolution the the capacitance between the two electrodes un- 60 weights are applied in combinations that Pay attention to the movements of the balance beam, a total weight between 1 and 10 units remains. Which give cooperating with the servo motor. A hand operated device of this Plate moves accordingly in accordance with the general type known from precision balances, with the movement of the beam, with the angular The second group of four arms and cam position the servomotor of the migration of the ball 65 can be used to set a second set kens is proportional. The invention is based on the weight of the z. B. ten times the value of the Drawings explained using an exemplary embodiment. first sentence has to muster; in the present In the drawings it represents a special case, however, it is used to explain how

described below to counteract the first set of weights.

The spindle 18 and the group of cam disks 16 are via a gear 20, 21 of a Electric motor 22 driven, which is preferably designed as a synchronous motor. The engine drives too a disk 23 over the gear 21, the edge of which can be seen through an opening in the base plate 11 and which is labeled in such a way that it shows the value of the weights placed on it.

The sleeve 19 and the group 17 of cam disks are driven by an electric motor 24 via a gear 25, 26 driven, and an indicator disc is also provided to indicate the value of the weights, which are placed on or lifted off from this group of cam disks.

Furthermore, two further cam disks 27 and 28 are provided on the spindle 18; the disk 27 is used for return, this disc with a Cam for actuating a microswitch 29 is provided, while the disc 28 is a self-holding Is a cam disk which has ten cams for actuating the microswitch 30. In a similar way it is the sleeve 19 is provided with a return cam 31 and a self-retaining cam 32, which work together with microswitches 33 and 34.

In the case of the one shown in FIG. 5, the device is fed by a power source, which for the sake of simplicity is indicated here as a battery 38, although in practice part or the entire system is operated from an AC power source, since it is desirable, that the drive motors 22 and 24 are synchronous motors. The battery lines lead via a main switch 39 and via a line 40 to one end point of a double-pole two-way switch 41. When the switch is turned to the left, the device is ready for operation and in such a position that the weights are automatically changed as required can. If the switch 41 is set to the right, then the device for placing the weights is operated so that it reaches an end or rest position in which all the weights of a group are either lifted from the balance beam or placed on it. When the switch 41 is in this position, one terminal of the battery is connected to the microswitches 29 and 33 via the conductor 40 and the conductors 42 α and 42 b. Since the feedback cam disk 27 and with it the group 16 of the cam disks are already in their end position, the cam of the disk 27 has opened the microswitch 29 and no further actuation takes place. The cam disk 31 and with it the group 17 of cam disks are not in their end or rest position, and the switch 33 is closed, so that the motor 24 with the battery 38 via the lines 40 and 42 b, the switch 33 and the line 43 is connected. The motor will then drive the cam disks until the switch 33 is opened by the cam of the disk 31 in the end position.

If the switch 41 is now turned to the left into its operating position, the battery is connected via the line 40, the switch 41 and a line 44 to the switches 6 influenced by the servomotor. These switches are operated from the servomotor by the spring arm 54 of the registration instrument 8, but they can just as easily be operated from another part of the servo system. The operation takes place so that the switch 6 a is closed when the pen reaches its maximum position, and the switch 6 b is closed when the pen is in its minimum position. It is assumed that as a result of a change in weight of the object being weighed, the pen reaches its maximum position and the switch 6 a is closed. The motor 22 is energized to drive the group 16 of cams so that weights are lifted in increments of 100 units corresponding to the area of the recording device until the pen is returned to the registration surface, whereupon the motor is stopped. Likewise, when the pen reaches its minimum position, the motor 24 is switched on to drive the group 17 of cams, whereby weights, again according to the recording area, are incrementally added until the pen is again within the scale.

This process is achieved in the following way:

When the switch 6 a is closed, the battery 38 is connected to the working winding of a relay 45 via the line 40, the switch 41, the line 44, the switch 6 a, the line 46 and the line 47. When the relay is energized, it closes its contacts 45 a and 45 b. When the contact 45 α is closed, the motor 22 is connected to the battery, via lines 47 and 48, while the closing of the contact 45 b has the consequence that the microswitch 30 is placed parallel to the servo switch 6 a . The purpose of this latter connection is to achieve that the motor is only stopped when the cams are in the predetermined position. As soon as the balance beam has been returned to a position that is within the sensitivity range by adding weights, and the pen of the recording instrument is on the effective part of the writing strip, the servo switch 6a is opened and the relay 45 is switched off . However, as soon as the motor 22 moves its group 16 of cam disks, the microswitch 30 is closed by the cam disk 28, so that the circuit is completed via the contact 45 b , which is used to hold the relay, even if the switch 6 a is opened. The motor therefore continues to run - until the next cam of the cam disk 28 opens the microswitch 30. If the switch 6 a has been opened, the relay will now drop out and the motor 22 will come to a standstill. This circuit thus ensures that the motor only stops when the microswitch 30 is opened by the cam disk 28, and this disk is arranged so that this can only occur when the arms for applying the weights which are controlled by the cam disks 16 stand either all the way up or all the way down so that they and the weights they carry cannot hinder the balance beam when swinging.

The motor 24 and the cam discs 31, 32 and 17 work in exactly the same way under the control of the servo switch 6 b and the relay 49, since the circuit is formed in the same way.

In the device described, both sets of weights and the object to be weighed are the same Effective end of the balance beam, and therefore add the motor 24 and the group of cams 17 weights added if the weight of the item is beyond the sensitivity range of the Balance beam goes out while the motor 22 and group of cams 16 remove weights, when the weight of the object falls below the sensitivity range of the balance beam. at Another embodiment can put the two sets of weights on opposite ends of the beam act. It can be seen that the same result with only one motor and one group of cams and weights could be obtained if the motor were made reversible. In the In practice, however, such an arrangement is more complicated to manufacture and also more expensive.

It is also clear that the number and size of the weights of each set of weights as well as the number of sets of weights can be changed. For example, there can be more or less than four weights in each set be present, and the weights do not need to be in the ratio 1: 2: 2: 5, but rather ratios of 1: 1: 2: 5, 1: 2: 3: 5 and 1: 3: 9: 27 e.g. B. can be used. It can also more than one set of weights may be provided for each direction, the sets e.g. B. as decadic sentences are arranged, and it can also be effective all sentences in the same direction. Such changes are based on the particular purpose for which the balance is to be used, and the necessary changes are known to those skilled in the art.

Other changes in the structure and construction of the system can also be made, without departing from the scope of the invention. While it z. B. is useful for synchronous motors Use the drive for the groups of cam disks, as this results in a constant actuation time is achieved, other types of motors can be used successfully. The cams can can also be given a shape that differs from the shape shown, and it is particularly possible the cam disks 27 and 31 with a notch in place of the cam for opening the microswitches 29 and 33 to be provided in the rest position of the groups of cam disks.

While the arrangement according to the invention for automatic weighing are used in the sense can that the device comes into operation after the application of a load to the Adjusting weights until equilibrium is achieved, this is the main application of the invention continuous weighing or the continuous registration of the weighing process. In this operating mode the balance is balanced after a load is applied and the device it then takes over to keep the balance beam within its sensitivity range, too when there are changes in the weight of the load. By adding or removing weights on your own every time the balance beam approaches or reaches the end of its range, can the range of the recorded weight change extended to the full capacity of the scale and this change can be read on suitably attached display dials, controlled by the device. When continuously registering the weighing process, off the number of swings of the bar can be closed, how often the quill pen crosses the border of the recording strip has reached.

Claims (4)

Patent claims: 1. Precision inclination balance for the continuous weighing of a load that changes over time, registered on a recording device, with an electrical transmitter element carried by the balance beam, which controls the putting on and off of switching weights at a predetermined deflection of the balance beam via electrical switching devices, characterized in that one in on The tracking device (3) carried by the balance beam (2) and controlling the recording device (8) in a known manner, when the limits of the inclination range of the scales and the limits of the recording device are reached via contacts (6 a, 6 b) , places or lifts the switching weights in such a way that that the switching weights each switch to the limit of the inclination area and the recording device which is opposite to the present limit. 2. Precision inclination balance according to claim 1, characterized in that the electrical device For switching on and off the switching weights of motors with constant speed, preferably Synchronous motors (22, 24), is controllable in such a way that the switching on and off of the shift weights synchronously with the movement of the Balance beam (2) takes place. 3. Precision inclination balance according to claims 1 and 2, characterized in that a Motor (22) the weight connection and the other motor (24) the weight loss when it is reached controls the respective limit deflections of the balance beam. 4. Precision inclination balance according to claim 1, characterized in that the tracking device consists of a capacitor, one of which is in a known manner on the balance beam fixed plate (1) of the other, via a servo motor (4) to a constant plate spacing adjustable plate faces. Considered publications:
German patent specifications No. 513 487, 513 966,
603119, 662 892; French Patent No. 816 908;
Swiss patent specification No. 262 590. For this purpose 2 sheets of drawings 409 629/100 6.64 © Bundesdruckerei Berlin