DE9010908U1 - Limit switch measuring gear - Google Patents

Description

Limit switch measuring gear

The invention relates to a limit switch measuring gear, in particular for handling and automotive equipment, for limiting the number

of the bypasses of external shafts, with coaxial disks driven by the shaft and a switch which switches at a certain relative position of the disks to each other.

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Mechanical limit switch measuring gears of the generic type have the task of exceeding &iacgr;

a given number of revolutions of a

Wave to cause the shutdown of its drive.

Such devices are used in the handling and automation industry (industrial robots) to control the manipulators and the

&igr; handled tools in case of malfunctions

such as cable breaks and software conditions to protect against collisions and damage that could otherwise be caused by inconsistent

controlled movements 7U. For this purpose, the limit switch measuring gears of the type used by the drive motor a given range of motion is spatially limited. For this purpose, the number of revolutions of the drive motor or the drive shaft driven by it must be limited to a given, but variable, number of revolutions. be limited.

In principle, a personal approach to the

& ■· - 5 -

rotations of the motor with the help of a gear reduction gear and the resulting reduction in the rotational speed of the shaft. However, the accuracy of such an arrangement is very low.

Furthermore, it is known from OE-GBM 89 01 571, which goes back to the same applicant, that by means of a device of the generic type, the number

&lgr; ¹⁰ of the revolutions in one direction. To limit the movement of a freedom

In order to achieve this, a limit switch must be installed in each direction for each end point, i.e.

A total of two are used. 15

On this basis, the invention has set itself the task of creating a limit switch measuring gear with the aid of which a reliable shutdown of the motor with precise switching accuracy at two different switching points can be achieved.

This task is solved according to the invention by three disks (5), (6), (7), of which at least two differ slightly in speed and the switch switches at a certain relative position of two or three disks (5), (6), (7) to each other.

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The core idea of the invention is to drive at least three coaxial disks through the shaft whose number of revolutions is to be measured, whereby the speed of the disks differs slightly. As a result of this arrangement, it can also be observed that after a

With each revolution of the shaft the spatial arrangement of the disks changes and only after a certain number of revolutions, which is determined in its absolute value, does the same relative position of the disks to one another arise through the respectively assigned number of the quotient of the speed ratios of the disks. The smaller the difference in the speed of the disks, the greater the number of revolutions in order to obtain the same relative position of the disks to one another. This will be explained in more detail using two disks whose specific gear ratio to each other is 10(:99. One of the disks then performs 100 and the other 99 revolutions in order to return to the relative position it initially occupied. This relationship applies analogously to a larger number of disks. The invention is based on the assumption that when two of the three disks are in a certain relative position to each other, the switch acting on the drive is activated. The result is that after a large number of revolutions of the shaft, the switch is activated for the first time.

The advantage that can be achieved with this invention is primarily the realization of high ratio of speed increase/reduction and the possibility of creating two different switching points, which allows speed limitation in two directions. Since the switch is switched directly or indirectly by the disk moving at a high speed, a high switching accuracy is achieved. In addition, a frontal placement on the shaft or the

^ Motor possible, so that there is easy access and readjustment from the front

can be easily accomplished. The low construction height facilitates the subsequent integration of the limit switch measuring gear according to the invention into existing systems. The high switching accuracy also means that the switching hysteresis, i.e. the distance between the on/off position, is very small.

The specific structural design, which determines the manner in which the switch is actuated in a certain relative position of the disks, is free within the scope of the invention within wide limits. In principle, both mechanical and optoelectronic triggering of the switch is conceivable. In the former case, switching elements are assigned to each disk, which lead to the triggering of the switch when the disks are in a certain relative position to one another.

For optoelectronic triggering, there is at least one opening in each disc, which passes through the openings when two or more discs are in a certain position relative to each other and is detected by a detector that triggers the switch. In other relative positions of the discs, the light beam is interrupted by one of the discs and the switch is therefore not activated.

In a preferred embodiment, some of the disks have pins that can be moved by cams on the adjacent disk against a restoring force. The movement of the pins by the cams defines the switching point.

With termination of the contact between cam and

Pins the latter return to their original positions.

In a special design, the pins are designed as curved springs with the end pointing outwards.

The spring provides the restoring force and the end pointing outwards is the actual pin that activates the switch.

It is also proposed to use a switching disk into which the pins engage. Since the speed must be limited in two directions, two pins acting at different points can be assigned to one and the same disk, which pivot the disks back and forth.

The advantage is that the force required to move the pin is very low and the switching process, which requires a comparatively high amount of force and corresponds here to the movement of the switching disk, can be carried out with a comparatively low amount of force due to the rotation of the disk. Another advantage is that, with the exception of the switching point, there is complete freewheeling between the two disks, i.e. there is no contact and therefore no wear can occur.

It is advantageous to keep the switch fixed in the on/off position in the usual way, so that overall a bistable behavior is achieved. If a switching disk is used, ball catches can provide stability in the two switching states.

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In order to increase the number of possible revolutions until the switching point is reached, it is recommended to install a reduction gear.

Further details. Features and advantages of the invention can be found in the following description, in which an embodiment of the invention is explained in more detail using the drawing. The drawing shows a perspective view of a limit switch measuring gear according to the invention, via a shaft

(l) the disks (5), (6), (7) are driven via three meshing gears (2), (3), (4), whereby the number of teeth of the gears {2), (3), (4) differs slightly, e.g. by a single tooth, for the same circumference. The result is that in addition to the rotation of the disks (5), (5), (7), these disks (5), (6), (7) also move relative to one another. A pin (8) projects radially from the lower and upper disks (5) and (7), which is moved axially, for example by a cam (not visible here) arranged on the middle disk (6), which presses the pins (8) axially downwards when two disks are in a certain relative position to one another.

The disks (5), (6), (7) are assigned a switch (9) with a pivoting switch disk (10) on the front. When the disks rotate, the pin (S) engages, if it protrudes, into the recesses in the circular

Switch disc (10) and in turn actuates the switch.

The result is a limit switch measuring gear that has a high gear ratio, high switching accuracy, very low switching hysteresis and no contact that is subject to wear.

Claims (9)

.PXyiypr|wwXLT..:: : DipL-Phys. Dr'.'w.PöttneV* European Patent Attorney · Europäischer Patentvertreter · Mandataiie en Brevets Europeans Kaiserstr. 27 · D-8700 Würzburg 1 · P.O. Box 63 23 ·» 0931/145 66 · Fax 0931/1 85 66 PATENT APPLICATIONS 1) Limit switch measuring gear, particularly for hand valves and automation devices, for the control of ,"■■ limit of the rotation of a wave, with coaxial disks driven by the shaft and a switch which switches at a certain relative position to each other, characterized by three rows (5), (6), (7), of which at least _ stePvS .7-iei differ slightly in speed and the switch switches at a certain relative position of two or three discs (5), (6), (7) to each other. 2) Limit switch measuring gear according to claim 1, characterized in that switching elements are arranged on each of the disks (5), (6), (7), two of which actuate the switch (9) at a certain relative position of two disks to each other. 30 3) End switch measuring gear according to one of claims 1 or 2, characterized by openings in each of the discs (5), (6), (7) through which a" certain position A light beam runs from two of the three discs to each other, triggering a switching process. 4) Limit switch measuring gear according to one of claims 1 to 3, characterized in that two of the disks (5), (6), (7) have pins (8) which can be locked by locking on one of the other of the disks (5), (6), (7) are movable against a restoring force. 5) Limit switch measuring gear according to one of claims 1 to 4, characterized in that the pins (8) engage in a switching disk (10) which is rotatable and arranged perpendicular to the disks (5), (6), (7). 6) Limit switch measuring gear, characterized in that the pins (8) are curved springs with an outward-pointing end. 7) Limit switch measuring gear according to one of claims 1 to 6, characterized by a bistable switch (9). 8) Limit switch measuring gear according to one of claims 1 to 7, characterized by two limit switches oriented against each other. 9) Limit switch measuring gear according to one of the claims 1 to 8, characterized by the connection of a reduction gear