DE29623537U1 - Angle measuring device - Google Patents

Description

DR. JOHANNES HEIDENHAIN GmbH 20 July 1998

Angle measuring device

The invention relates to an angle measuring device according to the preamble of claim 1.

It is known to mount angle measuring devices rigidly on a mounting surface of a drive device. The fastening is done using screws that pass through a flange of the angle measuring device and are screwed into the mounting surface. This method is labor-intensive and the drill holes in the flange must exactly match the thread in the mounting surface.

In order to avoid these disadvantages, it was proposed in accordance with DE 85 04 407 U1 that the angle measuring device be attached to the drive device using a clamping ring. This clamping ring encloses the two flanges of the angle measuring device and the drive device. The flanges must have the same external diameter and a lot of radial space must be available to operate the clamping ring, which means that its use is very limited.

Couplings are often used between a stator - for example a housing or a mounting flange - and a scanning device of an angle measuring device. Couplings are also used to rigidly connect a housing or mounting flange of the angle measuring device to a housing of a drive device in which the angular position of the rotating shaft is to be measured.

DE 29 06 432 C2 discloses a coupling device between the rotating shafts of an angle measuring device and an object to be measured, as well as between the stators of the angle measuring device and the object to be measured. The shafts are rigidly connected to one another without the possibility of compensation, and the stators are connected to one another via a parallel guide in a flexible but non-rotatable manner. Wobbling movements of the shafts are optimally compensated for by two parallel guides arranged perpendicular to one another, without the shafts and stators being able to rotate against one another. The coupling in the form of at least one parallel guide does not perform any rotary movements. The attachment of the coupling to the object to be measured is not explained.

20

A similar angle measuring device with a coupling between a motor housing and a housing (stator) of an angle measuring device is described in US-PS 4,386,270. The coupling is a bellows coupling, which is screwed axially to the motor housing by means of a mounting flange.

In order to avoid a wobbling movement of the housing (stator) of the angle measuring device, according to DE 32 06 875 C2 and DE 33 01 205 C2, the coupling is arranged inside the angle measuring device. In DE 32 06 875 C2, the coupling consists of an intermediate ring arranged inside the housing of the angle measuring device, which is connected on the one hand to the stationary scanning device via a pair of diametrically arranged springs and on the other hand to the housing of the angle measuring device via a pair of diametrically arranged springs offset by 90°. In DE 33 01 205 C2, the coupling consists of a spring

the bellows, which is arranged coaxially to the encoder shaft and connects the scanning device with the housing of the angle measuring device.

DE 89 15 109 U1 relates to an angle measuring device with a one-piece coupling with four leaf spring arms, each offset by 90° from one another and aligned parallel to the axis of rotation of the shafts. These leaf spring arms form two spring parallelograms arranged perpendicular to one another. Here too, the spring arms of the coupling are screwed axially to a drive unit.

DE 88 12 317 U1 and JP-62-155313 U also relate to angle measuring devices, in which the scanning device is attached to an object via a coupling. Spring plates pointing radially outwards have a common outer mounting ring. In DE 88 12 317 U1 it is proposed to attach the mounting ring to an object via holes and in JP-62-155313 U axial holes in the mounting ring and axial threaded holes in the object are provided for this purpose.

The object of the invention is to create an angle measuring device which is extremely compact and easy to install and which ensures precise coupling.

This object is solved by the features of claim 1.

The advantages achieved with the invention are in particular that the angle measuring device can be installed easily and in a space-saving manner. The radial and in particular the axial manufacturing tolerances of the elements required for assembly can be relatively large. Since the axial assembly position is not already fixed during production, angle measuring devices can be mounted to a drive device in the axial direction without preload using a coupling on the stator. The accuracy of the angle measuring device is thereby increased.

Advantageous embodiments of the invention can be found in the dependent claims.

Embodiments of the invention are illustrated in the drawings.
It shows

5 Figure 1 is a view of an angle measuring device with a

a clutch;

Figure 2 is a perspective view of a coupling;

10 Figure 3 a variant of the coupling;

Figure 4 is a plan view of a coupling with mounting elements

ment;

15 Figure 5 shows a cross-section of the coupling according to Figure 4;

Figure 6 is a plan view of another coupling with a

a mounting element;

20 Figure 7 shows a cross-section of the coupling according to Figure 6;

Figure schematically shows a mounting element with a

clamping element;

25 Figure 9 the clamping element according to Figure 8 in the clamped

ten state;

Figure 10 is a plan view of another embodiment and
30

Figure 11 shows a partial section of the embodiment according to

Figure 10.

An angle measuring device 1 shown in Figure 1 is connected via a coupling 2 35 to the stator 3 of a drive device 4. The shaft 5 of the

Angle measuring device 1 is rigidly coupled to the shaft 5' of the drive device 4. Free ends of axially parallel leaf spring arms 6 and 7 are connected to the stator 10 of the angle measuring device 1 by means of screws, which are visible in Figure 4. A housing 11 encloses the drive device 4 and the angle measuring device 1. The stator 3 of the drive device 4 is, for example, the stationary part of a motor. The stator 10 of the angle measuring device 1 is a stationary part of the angle measuring device, for example a mounting flange, the scanning device or the housing of the angle measuring device. The angular position of the shaft 5 relative to the stationary object 3 is measured by scanning a graduated disk 40 connected to the shaft 5 in a known manner by a scanning unit 41. In the example shown, the scanning unit 41 is rigidly mounted on the housing 42 of the angle measuring device 1 and on the mounting flange 10. The mounting flange 10, the housing 42 and the scanning unit 41 form the stator of the angle measuring device 1. The coupling 2 is provided in order to fasten these parts 10, 42, 41 to the stationary object 3 of the drive device 4 in a torsionally rigid but radially and axially flexible manner.

The coupling 2 shown in Figures 2 and 3 is designed as a single piece as a stamped and bent part and is made of a material with high fatigue strength, e.g. spring steel. The coupling 2 has a flat central area with four leaf spring arms 6, 7; 8, 9 running essentially parallel to the axis of rotation D, two of which (6 and 7 or 8 and 9) are arranged diametrically opposite one another. The leaf spring arms 6, 7, 8, 9 are aligned at least largely parallel to the common axis of rotation D of the parts 1 and 4 to be connected. They are arranged in pairs diametrically opposite one another and parallel to one another and thus form two spring parallelograms arranged perpendicular to one another, which ensure a torsionally rigid but radially flexible connection between the two parts 1 and 4.

The coupling 2 has a central opening 12 in the middle area, which is surrounded by further leaf spring arms 13, 14, 15, 16 in the manner of a framework. These leaf spring arms 13, 14, 15, 16 ensure a

torsionally rigid, but axially flexible connection in the direction of the rotation axis D of the two parts 1 and 4.

The two leaf spring arms 6, 7, 8, 9, which are each diametrically opposed and bent perpendicular to the flat central region 12, are advantageously also lattice-like, but designed as triangles, so that torques acting on the angle measuring device ¹ from the shafts 5, 51 are well absorbed and do not lead to a twisting of both stators 3 and 10.

In two of these opposing leaf spring arms 6, 7 there are two elongated holes 19 each, the longitudinal axes of which run parallel to the axis of rotation D. The elongated holes 19 allow adjustment between the two parts 3, 10 to be coupled when fastening them using screws to the angle measuring device 1.

The other two opposite leaf spring arms 8 and 9 have - as an extension of their base - almost circularly curved leaf spring arms 8a, 8b; 9a, 9b. These leaf spring arms 8a, 8b; 9a, 9b are pre-tensioned radially so that they must be pressed together when inserted into a tube 17 provided on the drive device 4. After insertion into the tube 17, the leaf spring arms 8a, 8b; 9a, 9b spread and the angle measuring device 1 is fixed in the drive unit 4 in a rotationally secure manner by the radially outward-directed portion of the spreading forces. The radial and axial compensating movements and angular misalignment are easily compensated.

If the leaf spring arms 8a, 8b; 9a, 9b are bent radially inwards at their free ends - as shown in Figure 2 - the leaf spring arms 8a, 8b; 9a, 9b can be spread radially with the help of clamping elements 18a.1 in order to increase the contact pressure on the inner casing of the cylindrical tube 17. Such a clamping element is shown schematically in Figure 2 as an axially screwable conical screw 18a.1. In Figure 2, the tube 17 is indicated with a double dot/dash line.

In a manner not shown, a positive connection can be achieved in the tube if the free ends of the leaf spring arms are bent radially outwards. They then engage, for example, in grooves arranged diametrically in the tube which are dimensioned accordingly to prevent rotational movement between the tube and the coupling.

The framework-like design of the leaf spring arms 6, 7, 8, 9 and 13, 14, 15, 16 shown in Figure 2 is not absolutely necessary for the invention. The leaf spring arms can also be designed and arranged, for example, according to DE-89 15 109-U1 or DE-88 12 317-U1. It is important that the coupling 2 is highly torsionally rigid and only allows axial and radial movements between the two parts 3 and 10 to be connected. A coupling in the form of two spring parallelograms arranged perpendicular to one another is particularly advantageous.

The coupling 3 shown in Figure 3 essentially corresponds to the embodiment shown in Figure 2, which is why the explanation of equivalent elements is omitted to avoid repetition.

The crucial difference to the embodiment described in Figure 2 is the design of the extended base of the spring parallelogram 8.3; 9.3. In the present embodiment the leaf spring arms 8a.3, 8b.3; 9a.3, 9b.3 are pre-tensioned inwards and encompass a correspondingly designed mounting projection 17 on the housing of the object to be measured (not shown) from the outside.

Here too, by bending the free ends of the leaf spring arms, a form fit with corresponding grooves in the mounting attachment can be created in a manner not shown, and a clamping element can engage directly on the leaf spring arms for radial clamping.

In the examples in Figures 1 to 3, the mounting element 18.1 and the clamping element 18a.1 are formed by the leaf spring arms 8a, 8b, 9a, 9b themselves.

Figure 4 shows a top view of a coupling 2.4 with a mounting element 18.4. Screws 29, 20, 21, 22 are used to attach the coupling 2.4 to the angle measuring device (not shown), as already indicated in Figure 1. The mounting element 18.4 is designed as a ring element which is essentially circular. The coupling 2.4 is connected to this ring-shaped mounting element 18.4 via further screws 23, 24, 25, 26.

To accommodate the angle measuring device with the mounting element 18.4, the stator 3.4 of the drive unit 4 has a tube 17.4 which has a specific inner diameter which is matched to the outer diameter of the mounting element 18.4.

The pre-assembled angle measuring device/assembly element unit is inserted into the tube 17.4 and the assembly element 18.4 is fixed in the tube 17.4 by means of an expansion body 18a.4 designed as a clamping element. In the exemplary embodiment, the expansion body 18a.4 is designed as a circular segment, which is formed by a detachable section of the assembly element 18.4.

The circular segment 18a.4 has a conical partial bore 18b on its flat section surface facing away from the outer circumference of the assembly element 18.4. The assembly element 18.4 also has a conical partial bore 18d on a surface 18c that is also flat and is opposite the flat section surface of the circular segment 18a.4, which corresponds to the partial bore 18b of the circular segment 18a.4. A conical screw 27, the cone of which corresponds to that of the two corresponding partial bores 18b, 18d, acts as an actuating element with a counter thread 28 that is located in the assembly element 18.4.

When the conical screw 27 is screwed into the counter thread 28 on the mounting element 18.4, the screw 27 slides in the two partial bores 18b, 18d and spreads them so that the circular segment 18a.4 is pushed off the mounting element 18.4 and pressed against the inner surface of the tube 17.4.

This process provides the simplest way to fix the angle measuring device, coupling and mounting element unit in the drive unit 4.

Figure 5 shows a cross section through the device according to Figure 4.

The conical screw 27 and the equally conical partial bores 18b, 18d in the mounting element 18.4 and the circular segment 18a.4 are particularly clearly visible here. The tube 17.4 of the drive unit is shown with double-dot/dash lines.

It is particularly advantageous if the expansion body is part of the assembly element itself, in that this part is connected to the assembly element via a weak point, for example, and can be pressed radially against a radially extending inner or outer surface via an actuating element - for example a conical or eccentrically shaped screw. The assembly element is designed to be so stable that it absorbs the counterforce of the actuating element, so that only the expansion body is deformed and no force acts on the coupling.

Figure 6 shows a top view of another embodiment of the invention. In this example, too, the scanning unit of the angle measuring device (not shown) is coupled radially and axially to the stator 3.6 of a drive device via the coupling 2.6. To easily attach the coupling 2.6 to the angle measuring device, the coupling 2.6 is also provided with an annular mounting element 18.6. To radially clamp this mounting element 18.6 to an inner surface of the tube 17.6, a clamping element in the form of an eccentric screw 18a.6 is provided in the mounting element 18.6. The head of this eccentric screw 18a.6 has an eccentrically running circumferential surface U, which comes into contact with the tube 17.6 when rotated and causes a radial clamping force between the mounting element 18.6 and the stator 3.6. In the example shown, the mounting element 18.6 is pressed with the stop surfaces 30 against an inner wall of the tube 17.6. Figure 7 shows a schematic cross-section of the device according to Figure 6.

Figure 8 shows a schematic illustration of another embodiment for radial clamping of a mounting element 18.8. Instead of the eccentric screw, a countersunk screw 27.8 is used as the actuating element. The conical surface F of the countersunk screw 27.8 acts on a washer 18a.8 when screwed into the mounting element 18.8 and moves it radially outwards, as can be seen in Figure 9. The washer 18a.8 is thus the clamping element which causes a radial clamping of the mounting element 18.8 within the tube 17.8 of the stator 3.8. As already mentioned, here too, a part of the mounting element 18.8 itself can be directly deformed using the countersunk screw 27.8 and cause the clamping.

Figures 10 and 11 show a schematic view of another embodiment. The coupling 2.10 for radial and axial compensation is attached to the ring-shaped mounting element 18.10. At least one radially extending slot 31 is provided in this mounting element 18.10. This slot 31 divides the mounting element 18.10 in such a way that the outer diameter of the mounting element 18.10 can be increased by a clamping element 18a.10 acting in the slot 31. This spreading of the mounting element 18.10 is carried out by two clamping elements 18a.10 arranged one behind the other at a distance in the axial direction. These clamping elements 18a.10 have opposing conical tapered surfaces which are supported on corresponding surfaces of the mounting element 18a.10. One of these clamping elements 18a. In the example shown, one is a screw and the other is a nut. By turning the screw, the two clamping elements 18a. 10 are pulled together, whereby the gap 31 increases due to the wedge effect. The screw can also be referred to as an actuating element. In a manner not shown, the screw can also only be supported in the axial direction on a flat surface, so that only the nut serves as a clamping element. To clarify, a cross-section of the clamping element 18a. 10 in the slot 31 is shown enlarged in Figure 11. Instead of a conical surface, a wedge-shaped surface can also be used.

In the embodiments described so far, the coupling 2 is attached to the angle measuring device 1 using screws. These screws can usually be inserted easily. However, if there are problems with this pre-assembly due to space constraints, it is also possible to provide a mounting element - for example a ring - to which the coupling is attached and which can be non-rotatably connected to the stator of the angle measuring device using the radial clamping according to the invention. A clamping element on the stator side can thereby create a radial clamping between the coupling and the mounting element and/or between the mounting element and the stator. Similarly, a clamping element on the object side can create a radial clamping between the coupling and the mounting element and/or between the mounting element and the stationary object. At which of these locations the clamping according to the invention is used depends on the space available.

It is particularly advantageous to use an annular mounting element 18, as it enables uniform clamping over the circumference. However, an annular mounting element 18 is not absolutely necessary.

In all the examples explained, it is advantageous if the radial clamping provides support in only three areas distributed over the circumference, i.e. if, for example, the mounting element 18.4 touches the tube 17.4 in three areas spaced apart in the circumferential direction. One of these areas should have a line contact (parallel to the axis

D) and a point contact should be made in the other two areas. This ensures that the two parts to be assembled together are clamped parallel to the axis.

The mounting element and the clamping element can also be part of the coupling, as shown for example in Figure 2. The leaf spring arms 8a, 9a, 8b, 9b form the mounting element 18.1 and the clamping element 18a.1. The mounting element and the clamping element can also be an integral part of the stationary object or the stator of the angle measuring device.
35

It is also possible for the coupling to be an integral part of the stator, in particular to be formed in one piece with the sheet metal housing of the angle measuring device. However, the coupling can also be formed in one piece with the stationary object.
5

The assembly according to the invention opens up the possibility of installing the angle measuring device directly inside the flange of a motor, i.e. in the motor bearing plate, without the need for material on the motor to accommodate threaded holes. The provision of a coupling between the stationary object and the stator is particularly advantageous, but not absolutely necessary. According to the invention, the stator (scanning unit) can be connected directly to the stationary object in a radial clamping manner. This is particularly advantageous for built-in rotary encoders in which the carrier of the scanning unit is to be installed in a motor without a housing and indexing disk.

In all embodiments with radial clamping, the clamping can act on an inner or outer circumferential surface. This circumferential surface is a surface that faces towards or away from the axis of rotation.

The axially accessible actuating element 27 or clamping element 18a is advantageously arranged between the outer contour of the angle measuring device 1 and the tube 17. This ensures that the actuating element 27 or clamping element 18a is axially accessible by means of a tool even in the assembled state.

The term radial defines a direction that is at least largely perpendicular to the axis of rotation D.

According to the invention, it is particularly advantageous to be able to arrange all the parts 18 required for mounting the clutch 2 to the stator 3 within the overall length of the clutch 2 itself.

Identical elements and elements with the same effect are provided with the same reference symbol, followed by the figure numbering as an index.

The invention can be used in angle measuring devices in the form of incremental and absolute rotary encoders, multiturns, revolution counters, resolvers and speed measuring devices. The scanning principle of the measuring embodiment can be optical, magnetic, capacitive or inductive.

Claims (17)

DR. JOHANNES HEIDENHAIN GmbH 20 July 1998 Claims 1. Angle measuring device (1) for measuring the angular position between a stationary object (3) and an object (5') that is rotatable relative to it about an axis of rotation (D), in that a measuring embodiment (40) is scanned by a scanning unit (41), wherein the scanning unit (41) is attached to a stator (10) of the angle measuring device (1) and between the stator (10) and the stationary object (3) a mounting element (18) for torsionally rigid attachment of the stator (10) to the stationary object (3) is provided, characterized in that the mounting element (18) has at least one clamping element (18a) for radial clamping between the stator (10) of the angle measuring device device (1) and the stationary object (3), which is arranged between the stator (10) of the angle measuring device (1) and a tubular inner surface (17) of the stationary object (3). 2. Angle measuring device according to claim 1, characterized in that the clamping element (18a) has a radially displaceable clamping surface, and that the clamping element (18a) or an actuating element (27) cooperating with the clamping element (18a) is aligned parallel to the axis of rotation (D) and is designed for clamping in this direction is accessible and operable. 3. Angle measuring device according to claim 1 or 2, characterized in that the stator (10) of the angle measuring device (1) is provided with an interposition of a torsionally rigid, but radially and axially flexible coupling (2) is attached to the stationary object (3), wherein the mounting element (18) is provided with at least one clamping element (18a) for radial clamping between the stator (10) and the coupling (2). 4. Angle measuring device according to claim 3, characterized in that the clamping element (18a) effects a radial clamping between the coupling (2) and the mounting element (18) or between the mounting element (18) and the stator (10). 5. Angle measuring device according to claim 1 or 2, characterized characterized in that the stator (10) of the angle measuring device (1) is attached to the stationary object (3) with the interposition of a torsionally rigid, but radially and axially flexible coupling (2), wherein the mounting element (18) is provided with at least one clamping element (18a) for radial clamping between the stationary object (3) and the coupling (2). 6. Angle measuring device according to claim 5, characterized in that the clamping element (18a) provides a radial clamping between the coupling (2) and the mounting element (18) or between the mounting element (18) and the stationary object (3). 7. Angle measuring device according to one of claims 1 to 6, characterized in that the mounting element (18) is arranged between the stationary object (3) and the stator (10), in particular or an annular body on or in which the clamping element (18a) is molded or attached. 8. Angle measuring device according to one of claims 3 to 6, characterized in that the mounting element (18) is rigidly attached to the coupling (2), in particular screwed on, or the mounting element (18) is integrally formed on the coupling (2). 9. Angle measuring device according to claim 7 or 8, characterized in that the clamping element (18a) is displaceable, rotatable or is deformable to effect a radial clamping between the mounting element (18) and the stationary object (3). 10. Angle measuring device according to claim 7 or 8, characterized in that the diameter of the mounting element (18) can be changed. 11. Angle measuring device according to claim 7 or 8, characterized in that the clamping element (18a) and/or an actuating element (27) has a surface extending obliquely to the axis of rotation (D) (18b, 18d, F), and by axial displacement of the actuating element (27) the clamping element (18a) is displaced radially. 12. Angle measuring device according to claim 11, characterized in that the actuating element (27) or the clamping element (18a) is a screw with a molded conical surface (F) which is mounted in the mounting element (18) so as to be rotatable about an axis parallel to the axis of rotation (D). 13. Angle measuring device according to claim 7 or 8, characterized in that the actuating element (27) or the clamping element (18a) has an eccentric surface (U) and is arranged to be rotatable about an axis parallel to the axis of rotation (D) in the mounting element (18). 14. Angle measuring device according to claim 13, characterized in that the eccentric surface (U) of the rotatable clamping element (18a) can be brought into contact with a surface (17) of the stationary object (3) or the stator (10). 15. Angle measuring device according to one of the preceding claims, characterized in that the coupling (2) consists of two orthogonally arranged parallelograms (6, 7; 8, 9), and each parallelogram (6, 7; 8, 9) consists of blades arranged parallel to one another. springs and at least the leaf springs (8, 9) of a parallelogram have a mounting element (18) for radial clamping on the stationary object (3) or on the stator (10). 16. Angle measuring device according to one of the preceding claims, characterized in that the stationary object (3) has a mounting tube (17), the inner surface of which serves for radial clamping. 17. Angle measuring device according to claim 16, characterized in that the mounting tube (17) is part of a motor (4).