DE2948440A1 - DEVICE FOR DETERMINING THE POSITION OF A MOVABLE COMPONENT RELATIVE TO A FIXED SUPPORT COMPONENT - Google Patents

Description

2948U0

description

The invention relates to a device for determination the position of a movable component relative to a fixed support component.

In particular, the invention relates to a device for determining the position of a movable slide a plastic injection molding machine, a machine tool or a hydraulic press etc., relative to the fixed frame part of the machine.

When carrying out the aforementioned determination of the situation Certain problems need to be resolved which are not limited to the accuracy with which these provisions are made is required, but which also result from the working conditions, under which the device must operate. Such a device can, for example, be significant over the long term Be exposed to vibrations and they often also contribute to Presence of dust and / or liquid lubricant jets work.

At present, optical measuring devices are offered which have photodetector elements (photodiodes, phototransistors etc.), which interact with traces of light. These photodetector elements and the Traces of light are each on two mutually movable

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Uauetetnenlen arranged and work together in such a way that for the respective relative position of the two components developed to each other proportional electrical signals will.

In addition, potentiometric measuring devices are used known, in which the movements of the movable component are transferred to a potentiometer slide and consequently signals are generated whose amplitude is proportional «! to the size of the movements.

The aforementioned optical or potentiometric devices have certain disadvantages that make use not particularly promote in continuous operation in production. So are the electric ones, for example Signal-generating components in motion in both cases (photodiodes etc. or the potentiometer slider), because they are arranged on the movable component. So they are subject to wear and tear and consequently require permanent maintenance, which is made more difficult by the fact that the action pollution or liquid lubricants can change their technical characteristics. About that in addition, the cost of such devices is typically high, so that they are not large-scale can be applied.

The disadvantages set out above become some of the disadvantages avoided in another measuring device, the substantially lor of a differential transforma is formed, its primary and secondary windings

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arranged on a fixed part of the machine are while a ferromagnetic core is moving Component is connected. Diesel 'core couples the transformer windings in such a way that one of the position of the movable component relative to the fixed machine part dependent output signal developed will. In such a case, however, the transformer must have a length twice as long as that is to be measured hub, which leads to the fact that the transformer is extremely bulky, if the hub for example is on the order of a meter or two.

In contrast, the invention is based on the object a device for determining the position of a movable component relative to a feston support component to create which does not have the disadvantages of the known devices described.

The inventive device for determining the Position of a component that is movable relative to a fixed support component is characterized by that a transformer with a ferromagnetic core rigidly connected to the movable component, one primary winding that can be connected to a feed device and one to processing devices connectable secondary winding is provided that the primary and the secondary winding mechanically are rigidly connected to the support component and are arranged coaxially to one another, the windings are designed in the manner of a solenoid so that they have a tubular channel inside them for receiving

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of the movable core so that each position of the movable component relative to the testing component a corresponding coupling factor between the primary and the secondary winding is determined and a voltage signal corresponding to the relative position can be obtained from the secondary coil of the two components is directly proportional to one another.

The invention is described in the following description of a preferred embodiment in conjunction with FIG Drawing explained in more detail, namely shows:

1 shows a sectional view of the sensor element of the device according to the invention;

Fig. 2 is an enlarged perspective partial view of a single unit: of Fig. 1; and

Fig. 3 shows an electrical ^ functional circuit of a device constructed in the manner according to the invention.

Fig. 1 shows a fixed plate 11 and a movable one Plate 12, in a manner not shown on a Support component or a movable slide a Injection molding machine are attached.

The movable plate 12 is displaceable at right angles to the plate and carries a ferromagnetic tubular element 13t which is arranged projecting at right angles on the side of the plate 12 facing the plate 11 and is provided with a longitudinal slot 1 k .

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During the movement of the plate 12 relative to the plate 11, the tubular element slides in a passage. 1 'hole 16 in the plate 11 and in a tubular Component 17 »which is made, for example, of Bakelite and one end of which is not shown Way is attached to the plate 11.

A secondary winding 19 and a primary winding 20 are coaxial around the tubular component 17 wound so that they are coupled to each other and form a transformer 21. The secondary winding is evenly wound from one end to the other of the tubular member 17, while the primary winding 20 from one end of the tubular component from a first section 22, which is in a first Winding sense, for example clockwise, is wound, and one with the section 22 electrically in Has a second section 23 connected in series but wound in the opposite direction of winding.

The secondary winding I9 and the primary winding 20 of the Ti'ansforniators 21 are through the tubular element magnetically coupled, which forms a movable core and can move so that the coupling only between section 22 of primary winding 20 and the corresponding section of the secondary winding iy he follows. In addition, sections 22 and 23 a number of turns, dLe are so designed, Let them in air have two associated magnetic fluxes opposite one another Generate greatness. Shut up, I know

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Section 22 has a winding pitch which compensates for any response irregularity of the transformer 21 and a substantially linear transfer function (movement of the core 13} induced voltage on the secondary winding 19) between the primary winding 20 and the secondary winding 19.

The tubular component 17, the secondary winding 19 and the primary winding 20 are surrounded by a jacket core 2k , which is fastened to the plate 11 with a flange section 25 and is made of ferromagnetic ™ material in order to shield the magnetic flux generated by the transformer 21 from the outside. A screw 27 is screwed into the end wall 26 of the jacket core 2k opposite the flange section 25 and carries an auxiliary magnetic core 28 at one end 23 of the primary winding 2O is aligned, and its position can be axially adjusted by means of the screw 27 in order to obtain a coupling effect between the section 23 and the associated slope of the second winding 19 that can be adjusted over a wide range.

3 shows schematically a functional circuit diagram from which the supply of the transformer 2 1 and the Processing of the electrical signals it generates emerges. From a preferably sinusoidal Vibrations with an output frequency in the order of magnitude of a few KHz generating oscillator 33

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a signal is fed to the terminals 31 and 32 of the primary winding 20. Connections 34 and 35 of the secondary winding 19 are each connected to a first and a second input of a rectifier circuit tuny "} G , the first output of which is connected to ground and the second output of which is connected to the input of an amplifier 371, in particular a DC voltage amplifier, which in turn is equipped with devices for Setting the gain and the zero level of the output signal is provided * The amplifier 37 is also connected to ground and its output is connected to a connection 39, to which the first connection of a DC voltage measuring instrument 40, for example a moving-coil voltineter, is then connected again whose second connection is to earth potential.

The transformer 21, the oscillator 33 »the rectifier circuit 36, the amplifier 37 and the measuring instrument 40 as a whole constitute one device for determining and displaying the position which the movable plate 12 has relative to the fixed plate occupies. The operation of the device 44 is as follows »

The device is calibrated on the one hand so that there is a relationship between the relative positions of the Plates 12 and 11 and the respective DC voltage indicated at connection 39 by measuring instrument 4o. This is done by the fact that the plate 12 so far from

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the plate 11 is pulled away so that the free end of the tubular core 13 is in the through hole 16 of the plate 11 in such a position that it does not cause any magnetic influence on the primary winding 20 and the secondary winding 19 of the transformer 21. These windings are therefore air-coupled, and each signal fed to the primary winding 20 by the oscillator 33 induces two magnetomotive forces of equal and opposite magnitude in the sections 22 and 23 of the primary winding. The flux generated by the primary winding 20 is therefore equal to zero and the instrument kO does not measure an electrical signal at the connections Jk and 35 of the secondary winding 19. If the electrical signal is not exactly zero, the display on the instrument kO can be adjusted to zero by adjusting the axial position of the auxiliary magnetic core 28 by means of the screw 27. As a result, the coupling coefficient between the section 23 of the primary winding 20 and the corresponding section of the secondary winding 19 is changed so that the two magnetomotive forces are fully compensated.

When the plate 12 then approaches the plate 11, the core 13 enters the tubular component 17 and causes a stronger coupling between a portion of portion 22 of primary winding 20 and 14 a corresponding part of the secondary winding iy over the tubular core I3. As a result, the

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The magnetomotive force generated by the section 22 is greater than that of the section 23, so that an alternating current signal is produced at the connections "} k and 35 of the secondary winding 19, the amplitude of which is proportional to the axial section of the core 13 engaging in the tubular component 17. This The signal is rectified in the rectifier scarf 36 and amplified in the amplifier 37 and can be measured via the measuring instrument kO connected to the terminal 39, the scale of the measuring instrument being calibrated directly so that it shows the movement of the plate 12 relative to the plate 11 in millimeters or centimeters, since the portion 22 of the primary winding 20 has a slope which allows a substantially linear transfer function to be obtained between the primary terminals 3I and 32 and the secondary terminals 3k and 35 when the axial position of the tubular core I3 changes, that at the terminal increases 39 voltage that can be removed linearly from zero to a maximum value rt, for example 10 volts, when the movable plate 12 moves from a position of maximum distance to the fixed plate 11 to a position of minimum distance.

A review of the properties of the invention shows that the measuring and display device hk meets the objectives set.

In this connection, if it is assumed that the frequency of the signal generated by the oscillator 33 is at 1 KHz and the plate 12 a speed

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from 1 m / aec. relative to the plate 11, then it is possible to determine the movement of the plate 12 with an accuracy of the order of magnitude of 0.5 mm, which corresponds to the required average accuracy of the machines in which the device kk is to be used.

In comparison to known devices with a differential transformer, the jacket core 2k of the transformer 21 extends in the longitudinal direction only over the length of the stroke to be measured, so that the total length of this known device is reduced to half. In addition to the shielding of the magnetic flux generated by the primary winding 20, the jacket core 2k also acts as a shield against electrical interference which is absorbed by the windings of the transformer 21 and which could then lead to measurement errors. Finally, the jacket core 2k also provides good mechanical protection for the winding of the transformer 21 against impacts to which the transformer can be exposed during normal operation of the machine on which it is arranged.

The tubular core 13 can be made in any length and is usually made of soft iron so that it can be manufactured at low cost. The longitudinal slot 1 k significantly reduces losses due to extraneous or eddy currents introduced in the core and improves the overall efficiency.

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When the change to be measured relative movement in the length of a few tenths of centimeters to several meters, no significant changes of the winding system for the primary winding 20 and secondary winding 19 are of the transformer 21 or the different associated electronic supply and measuring devices required. This is due to the fact that when the length to be measured changes, the diameter and the number of turns of the conductive wires of the winding can be changed so that the same input impedance at the terminals 31 and 32 of the primary winding 20 and at the terminals 3 ^ and 35 of the secondary winding 19 not only have the same output impedance in each case, but also a voltage which, after rectification and amplification, is always in the range between the same minimum value (e.g. 0 V) and the same maximum value (e.g. 10 V), It is therefore possible to use the same type of oscillator, rectifier circuit, amplifier and measuring instrument for each length of movement to be measured with the device hk .

Since the amplifier 37 has an adjustable gain and also with means zuijfcins division its zero level is provided, it is possible to measure a specific movement of, for example 1 m adjusted measuring device to adapt so that it also shorter movement lengths, for example can measure in the order of a 2 m, or that alternatively also a middle part the transfer function for motion in ■ gnawing, for example in the range between: v "cm and 80 cm,

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can be used. By suitably setting the gain of amplifier 37 and compensating its output signal to zero level, it is possible to obtain a DC voltage signal at terminal 39, the magnitude of which is always between the same minimum and maximum values, and the magnitude of which can be read on the measuring instrument kO.

In comparison to optical or potentiometric measuring devices, the fiction s ge measured measuring device hk does not have any electrical signal generating components that are constantly in motion. As a result, there is also no wear that would require special maintenance.

Since the winding system for the primary winding 20 and the secondary winding 19 is essentially the same regardless of the movement length to be sneezed, and since the components of the measuring device hk do not need to be constructed with a high degree of precision, the cost of the measuring device hh is low.

Finally, within the scope of the inventive concept, modifications and developments of the described Embodiment are realized.

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ORIGINAL INSPECTCD

Claims (1)

PATENTANWÄLTE HELBEFl S ZENZ ElEBSfcH WEIi Λ / BMJ ZWINGENBEHB TEL. ΟΒΞ51- 74106 2948U0 S 79Π FRATELLI SANDRETTO SpA, Via E. De Amicis kh, I-1OO97 Regina Margherita, Italy Device for determining the position of a movable Component relative to a stationary one Support component Expectations 1.) Device for determining the position of a relative movable to a fixed support component Permanent finents, characterized in that there is a transformer (21) with one with the movable component (12) rigidly connected ferromagnetic core (il), one that can be connected to a feed device Primary winding (20) and one on processing equipment connectable secondary winding (19) is provided that the primary and the secondary winding (20; 19) mechanically 3tarr with the Trag-chewing element connected and coaxial to each other 0 3 oo 7 a / η · ΐ »7 ORIGINAL INSPECTED 2948U0 are arranged, the windings are designed in the manner of a solenoid so that they are in their Inside a tubular channel (17) for receiving of the movable core (13), whereby each position of the movable component (i2) is relative to the fixed component (11) a corresponding coupling factor between the primary and the secondary winding (20 j 19) and a corresponding voltage signal 1 from the secondary coil (19) obtainable is which of the relative position; the both components are directly proportional to each other. 2. Device according to claim 1, characterized in that the primary winding (20) of the transformer (21) has a first and a second section (22; 23) which are wound in opposite Windungssiim and axially adjacent that the first section (22 ) is wound with a significantly lower winding pitch than the second section (23 ) , and that the movable core (it) can only be introduced into the tubular channel (17) over a first length section corresponding to the axial extent of the first section (12) . 3. Apparatus according to claim 2, characterized gekcmizeiclmet that the first and the second section (22; 23) generate magnetomotive forces in air of the same magnitude, but with opposite signs, and that the voltage signal obtained from the second winding (1 ')) in the is essentially equal to NuIJ when the movable core (13) is outside the first section (22) of the primary winding (20). 0 3 0 0 2 8/05 «? ORDINAL 2948U0 U. Device according to claim 2 or 3, characterized in that a ferromagnetic auxiliary magnetic core is arranged axially adjustable within the tubular channel (17) in a position aligned with the second incline (23) of the primary winding (20). 5. Apparatus according to claim h, characterized in that the movable core (13) has a tubular structure. b. Device according to claim 5 »characterized in that the tubular core (13) has an axially extending core Has slot (14). 7. Device according to one of claims 1 to 6, characterized in that the solenoid-like wound primary and secondary windings (20; 19) are arranged within a tubular ferromagnetic jacket core (2k) . 8. Device according to one of claims 1 to 7, characterized in that the feed device an oscillator circuit for the primary winding (20) (33). '). Device according to Claim 8, characterized in that the oscillator circuit (33) generates an electrical signal at its output with a frequency of the order of magnitude of KHz. 030028 / Ohü7 10. Apparatus according to claim 8 or 9, characterized in that the oscillator (33) generates sinusoidal signals. 11. Device according to one of claims 1 to K), characterized in that the processing devices include a rectifier circuit (36) for that obtained from the secondary winding (1 °) Have voltage signal. 12. The device according to claim 11, characterized in that that the processing devices have an amplifier circuit (37) for direct current signals, which is arranged in series with the output of the rectifier circuit (36) and has adjustment devices for the gain. 13 · Device according to claim 12, characterized in that that the amplifier circuit (37) is provided with devices for setting the voltage level of the output signal. 14. Device (kk) for determining the position of a movable component (12) relative to a fixed support component (11) as described in connection with the accompanying drawings. 030028/0537