EP0543213B1 - Movable collector or wiper for potentiometer - Google Patents

Abstract

In the case of a movable collector for potentiometers, adjustable resistors and the like, it is proposed to arrange moving individual wiper fingers, consisting of small round wires, parallel to one another in groups or to a wiper finger carrier, and intervals corresponding approximately to the width of the group, so that wear products and dust can be deposited between the wiper finger groups without interfering with operation. <IMAGE>

Description

The invention relates to a movable tap for rotary and linear potentiometers, adjustable rotary resistors and. Like., Preferably for fast moving potentiometers for control and regulation technology according to the preamble of claim 1.

A known tap device of this type (DE-PS 33 40 635) has a grinder made of a one-piece, electrically conductive spring material which merges into a plurality of grinder fingers arranged in parallel in the transition region between the respective resistance or collector path on which it slides.

It is also possible to design such a movable tap or grinder (DE-PS 27 06 760), that with a plurality of grinder fingers arranged parallel to one another and simultaneously grinding on the track and connected at one end to one another in a connection area, a soft-elastic, elastomeric plastic material with high internal friction is applied to at least two mutually opposite sides of the grinder fingers, as a result of which especially in the case of fast-running Potentiometers an effective damping of wiper finger movements is possible. In this way, despite the microscopically considerable bumpiness of the surface areas of resistance and collector tracks on potentiometers on which the wiper fingers slide, comparatively smooth oscillating movements of the wiper fingers can be ensured, so that there is no rocking of vibrations due to the spring properties that are necessarily present in wipers a correspondingly rapid destruction occurs.

In this context, it is also known to arrange the individual wiper fingers close to one another on a preferably resilient carrier part, for example by spot welding on the spring part, which results in a certain mechanical damping of the movements of the individual wiper fingers with respect to one another, because of the adjoining and adjacent surfaces the individual grinder fingers running parallel to each other creates a mechanical friction which, due to the statistical distribution of the grinder finger movement, ensures that on average the individual Grinder fingers are calmed in their vibration behavior. Various embodiments of such grinder finger tapping systems, in which small round wires are dotted parallel to another carrier, can be found, for example, in a PKV 20 brochure from Heraeus with the designation "multi-wire grinder".

Such a movable tap for rotary and linear potentiometers, adjustable resistors and the like. is also known from DE-A-2 047 679. This tap has a resilient intermediate carrier with a large number of individual, adjoining, parallel grinder fingers sliding directly on the resistance track and / or collector track, with a first group of grinder fingers laterally having a gap or a distance approximately in the order of magnitude of the width of the grinder finger group is connected, which in turn is followed by a further group of wiper fingers, so that at least one gap, delimited on both sides by wiper finger groups, is formed in the parallel overall sequence. With this tap, the individual wiper fingers are also designed as small round wires bent at the bottom.

Nevertheless, with such tap systems there is the problem that due to the relative movement between grinder fingers and runway, abrasion or other wear products occur, which are permanently deposited at any point, not least on the grinder fingers, which form a continuous surface due to their directly adjacent structure, so that there may be problems in the intended functional sequence.

Advantages of the invention

The invention solves this problem with the features of claim 1 and creates for the wear products resulting from the relative movement of wiper fingers and runway and the abrasion in that the wiper fingers themselves comprise a predetermined number of wiper fingers closely grouped in the longitudinal direction and that the lateral distance the grinder finger corresponds approximately to the size of such a group of grinder fingers, gaps already in each individual grinder finger, in which the abrasion can be deposited without problems and without disturbing the movable tap. In addition, the tap is significantly improved by such a design of the wiper fingers in that the wiper fingers have better spring behavior.

Studies have shown that this results in considerable improvements in the life of those with the grinder fingers according to the invention equipped potentiometers, with a further advantage that less wiper fingers are effectively required, so that the cost structure improves, since such wiper fingers usually consist of a noble metal.

The advantages of the present invention can be seen both in the known scratch grinder embodiments, in which a bent grinder finger tip slides on the slope, and in skid grinders, in which the grinder fingers rest and slide with the bending radius on the resistance or collector track.

drawing

Fig. 1

eine mögliche Ausführungsform eines Schleifers mit von ihm ausgehenden einzelnen Schleiferfingern, die auf einer zugeordneten Piste (Widerstandsbahn, Kollektorbahn) gleiten, in Seitenansicht und

Fig. 2

den gleichen Schleifer in einer Ansicht von unten entsprechend dem Pfeil F der Fig. 1;

Fig. 3

mehrere nebeneinander liegende einzelne Schleiferfinger-Trägerteile in U-Form in Draufsicht, wobei jeder U-Schenkel zueinander über Abstände getrennte Schleiferfingergruppen lagert und

Fig. 4

zum besseren Verständnis U-förmige Schleiferfingerträger in lediglich doppelt so großem Maßstab, bezogen auf natürliche Größe.

Exemplary embodiments of the invention are shown in the drawing and are explained in more detail in the following description. Show it:

Fig. 1

a possible embodiment of a grinder with it from individual grinder fingers that slide on an associated slope (resistance track, collector track), in side view and

Fig. 2

the same grinder in a view from below according to the arrow F of Fig. 1;

Fig. 3

several side-by-side individual wiper finger support parts in a U-shape in plan view, each U-leg supports separate groups of wiper fingers over distances and

Fig. 4

for better understanding U-shaped grinder finger carriers on a scale that is only twice as large, based on natural size.

Description of the embodiments

3 shows, in large enlargement, each U-shaped intermediate carrier 10a, 10b, 10c, the two legs 11a, 11b of which are each integrally connected to one another via a base web 12 and, in this respect, are also electrically conductively connected to one another, and with grinder fingers 13a, 13b at the ends of the legs , 13c, 13d fastened in a suitable manner, preferably and for example by spot welding.

The procedure is such that the individual wiper fingers 13a, 13b, 13c, 13d, belonging to a wiper area, such a grinder area in the embodiment shown in FIG. 3 can be formed, for example, by each end of each leg 11a, 11b of the U-shaped intermediate carrier, arranged in groups.

In the exemplary embodiment shown, four wiper fingers 13a, 13b, 13c, 13d, for example, are arranged at each leg end, each wiper finger 13a, 13b, 13c, 13d in turn being formed from three directly adjoining individual wiper fingers 14.

In any case, the arrangement of the grinder fingers 13a, 13b, 13c, 13d for each grinder area is such that a number of fingers are arranged adjacent to one another in parallel in mechanical frictional contact, to which group there is a gap, for example the same width as the one mentioned Has wiper finger group; This gap, which is denoted overall by 15 in FIG. 3, is followed by a further group of wiper fingers, preferably with the same number of wiper fingers 14 and immediately, if desired.

This results in a preferred division of wiper fingers for each wiper area, namely by maintaining the desired effect of the mechanical internal damping of the wiper fingers relative to one another, in that the wiper fingers in each group of wiper fingers are dampened in their movement by the mutual frictional contact, while simultaneously following a predetermined one The number of wiper fingers is followed by a larger gap, which serves to absorb wear products and abrasion, but which also ensures that the uncontrolled movements of individual wiper fingers do not affect the entirety of all wiper fingers in a wiper area - precisely because they are in parallel frictional contact lie to each other - but that such uncontrolled movements that may occur are then only limited to the one group of wiper fingers in which they occur. In other words, this means that the remaining groups of wiper fingers continue to maintain perfect contact with the respective runway on which they slide - this also results in an improvement in both the mechanical running properties and the electrical transmission properties of the wiper.

In the illustrated embodiment, each leg end of each U-shaped intermediate carrier has four wiper fingers 13a, 13b, 13c, 13d, which are each formed from three individual wiper fingers 14, so that here one wiper area has a total of twelve individual wiper fingers, but which have corresponding distances between them form with simultaneous group formation.

Such a grinder finger area can be defined as a tapping device for a specific resistance track or collector track, in which case the other leg, which is connected to the first leg via the base of the U-shaped intermediate support, forms a further grinder area which then, accordingly, on an assigned collector track or resistance track slides.

For a potentiometer, only such a U-shaped intermediate carrier can be provided and fastened to a movable tap which, in turn, then slides with its wiper fingers 13a, 13b, 13c, 13d, which in turn comprise a plurality of wiper fingers 14, on the respective leg ends on the resistance track and collector track and so on transfers the potential tapped from the resistance track to the collector track.

However, it is also possible to equip a tap 16, as shown in FIGS. 1 and 2, with, for example, two of the U-shaped intermediate carriers, the legs of which are equipped with the wiper finger carriers arranged in groups, then either on a total of two resistance paths and correspondingly two collector paths slide or use one of the U-shaped intermediate supports in total to tap or contact a respective resistance track and another to tap or contact a corresponding collector track, the electrical connection between the two U-shaped intermediate supports 10a ', 10b' at the tap 16 then takes place in a suitable manner by connecting the two U-shaped intermediate carriers or via the tap 16 itself.

The U-shaped intermediate carrier 10a, 10b ... preferably consists of an electrically conductive, elastic spring material and can be bent as can be seen in the U-shaped intermediate carrier 10 shown in a side view above the intermediate carriers 10a, 10b ... is. From this representation it can also be seen that the respective individual Grinder fingers 14 are attached to the end region of each leg 11a, 11b overlapping it over a predetermined distance.

The illustration in FIG. 3 shows a so-called scratch grinder, in which the grinder slides with the bent end region on the associated runway, that is to say the resistance track or the collector track; the invention is equally suitable for skid grinders in which, in reverse, so to speak, the grinder finger with the bending radius 17 (FIG. 3) slides on the slope.

Since neither the naked eye nor the distances between them can be seen with the naked eye in view of the actual tinyness of the individual wiper fingers, a measurement is deliberately provided in the illustration in FIG. 3 above, which can be seen that, however, only in this exemplary embodiment and thereon The invention is understandably not limited, the total width of a grinder area can be approximately 1.5 mm, the width of each of three grinder fingers 14a, 13b, 13c, 13d forming 0.23 mm and the distance between the individual ones such groups of grinder fingers 14 is 0.2 mm.

Such grinding finger structures can be produced with high precision using suitable automatic machines, and since the wear products and abrasion occurring during the operation of such potentiometers and corresponding systems are also relatively minimal, the gaps provided by the invention are fulfilled between the wiper finger groups of one wiper finger area in an impeccable manner. Fig. 4 shows, in order to stay with the specified orders of magnitude, in each case juxtaposed U-shaped intermediate carriers with gripper fingers pointed at them, on a scale twice as large as in reality, so that one can get an idea of the actual dimensions.

The essential aspects of the present invention are therefore not only the mechanical damping properties which are improved by the formation of the individual wiper fingers, in turn, as groups of even smaller wiper fingers 14, and the possibility of now absorbing wear products without functional disturbances, but also that while maintaining them, they are equally good Tapping properties with a considerable, possibly doubled service life in about half of the previously required grinder fingers is required to ensure the same functions. This also results in considerable cost savings.

Claims (3)

1. A movable pick-off for rotary and linear potentiometers, variable resistors, preferably for rapidly moving potentiometers for automatic control engineering, for transmitting voltages or currents from resistor and/or collector tracks which are moving relative to the pick-off, comprising a flexible subcarrier and a plurality of individual wiper fingers (13a, 13b, 13c, 13d) which slide directly on resistor and/or collector tracks and which are arranged parallel side by side in groups, a gap or space approximately in the order of the width of the wiper finger group laterally adjoining a first group of wiper fingers (13a, 13b, 13c, 13d), the said space in turn being adjoined by another group of wiper fingers (13a, 13b, 13c, 13d), so that there is at least one gap defined on either side by wiper finger groups formed in the whole parallel sequence, characterised in that the wiper fingers (13a, 13b, 13c, 13d) themselves comprise a predetermined number of wiper fingers (15) closely adjoining one another in the longitudinal direction in groups, and in that the lateral spacing of the wiper fingers approximately corresponds to the size of one such group of wiper fingers (15).
2. A movable pick-off according to claim 1, characterised in that the wiper finger groups are carried by the end regions of arms (11a, 11b) of U-shape subcarriers (10a, 10b, 10c) to which they are spot welded in group formation, and in that the U-shape subcarriers are themselves secured to the movable pick-off.
3. A movable pick-off according to claim 1 or 2, characterised in that three wiper fingers (14), located side by side in adjacent mechanical damping contact, form each wiper finger group, and in that four such groups, secured to the end of one subcarrier arm (11a, 11b), form respective wiper regions consisting of four wiper fingers (13a, 13b, 13c, 13d).

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