Multi-turn angle measurement device

Abstract

The invention relates to a multi-turn angle measurement device for measuring multiple revolutions of a shaft (4), consisting of a first code carrier (31) with an optical single-turn scanning function (34) for detecting the absolute position of the shaft and a second code carrier for measuring the number of revolutions of the shaft (4). A reduction gear (2) is arranged between the first code carrier (31) and the second code carrier, and the second code carrier consists of a number of permanent magnets (22), the position of which is detected by an assembly of Hall sensors (16a-16b) fixed to the housing. Each of the permanent magnets (22) is embedded into the plastic material of the transmission gears (20) of the reduction gear (2).

Claims

1. Multi-turn angle measurement device for measuring multiple revolutions of a shaft (4), consisting of a first code carrier (31) with an optic single-turn scanning function (34) for detecting the absolute position of the shaft and a second code carrier for measuring the number of revolutions of the shaft (4) wherein a reduction gear (2) is arranged between the first code carrier (31) and the second code carrier, and the second code carrier consists of a plurality of permanent magnets (22), the position of which is detected by an assembly of Hall sensors (16a-16c) fixed to the housing, characterized in that each of the permanent magnets (22) is embedded in the plastic material of the transmission gears (20) of the reduction gear (2) and that the respective transmission gear (20) is held on its corresponding axle (19a-b) with a snapping mechanism, wherein a magnetic force exists between the magnetic axle (19a-19b) and the permanent magnet (22).

2. Multi-turn angle measurement device according to claim 1, characterized in that the magnetization of the permanent magnets (22) occurs after they are embedded in the plastic material of the transmission gear (20) in the injection mold.

3. Multi-turn angle measurement device according to claim 1, characterized in that a magnetic force is an axial pretensioning force.

4. Multi-turn angle measurement device according to claim 1, characterized in that only a single conductor plate (7) is present on whose underside the single-turn scanning function (34) and on whose upper side the magnetic multi-turn scanning function are arranged.

5. Multi-turn angle measurement device according to claim 1, characterized in that a two-level design with two conductor plates (7, 35), which are arranged at a reciprocal axial distance, is present.

6. Multi-turn angle measurement device according to claim 5, characterized in that the second conductor plate (35) is arranged above the transmission (2) and the first conductor plate below the transmission (2).

7. Multi-turn angle measurement device according to claim 5, characterized in that the magnetic scanning function is arranged on the second conductor plate (35).

8. Multi-turn angle measurement device according to claim 1, characterized in that an evaluation circuit is provided, which, in a first step, provides a first sensor (37) in which the respective Hall sensor (16) is embedded, and a number of Hall sensors (16) are embedded and thus form a matrix in the sensor (37).

9. Evaluation circuit for a multi-turn angle measurement device according to claim 1, characterized in that the staggered evaluation circuits assigned to the sensors (37) are serially connected in the form of a Daisy chain circuit.

Description

(1) FIG. 1: shows a perspective view of a multi-turn rotary encoder

(2) FIG. 2: shows the side view of the rotary encoder according to FIG. 1

(3) FIG. 3: shows a detailed representation according to detail Ill in FIG. 2

(4) FIG. 4: shows a perspective view of a conductor plate

(5) FIG. 5: shows the perspective view of the conductor plate according to FIG. 4 with the optimal placement of spacer rings

(6) FIG. 6: shows a carrier plate for the reduction transmission

(7) FIG. 7: shows the finished reduction transmission connected to the carrier plate according to FIG. 6

(8) FIG. 8: shows a representation of the assembly of the transmission according to FIGS. 6 and 7 on the conductor plate according to FIG. 5

(9) FIG. 9: shows the finished assembly according to FIG. 8

(10) FIG. 10: shows a local section along the intersection line X-X in FIG. 1

(11) FIG. 11: shows the same local section as FIG. 10 with further details

(12) FIG. 12: shows an embodiment that has been modified from the one in FIG. 11 with a two-level design of the rotary encoder

(13) FIG. 13: shows a functional diagram of an electric evaluation circuit for the multi-turn rotary encoder

(14) FIG. 14: shows a functional diagram for the single-turn evaluation

(15) FIGS. 1 to 3 show a multi-turn rotary encoder 1, which essentially consists of an upper reduction gear 2, whose carrier plate 12 is made from plastic material.

(16) In another design, it may also be provided, however, that this carrier plate 12 is made from light metal pressure casting material.

(17) The reduction gear 2 comprises a central recess 3 through which the free end of a shaft 4 protrudes and whose angle of rotation is to be detected by the multi-turn rotary encoder.

(18) The carrier plate 12 braces itself against a conductor plate 7 located below it by means of axial lugs 5 that are evenly distributed around the circumference. Between them, supports 6, which brace themselves against the upper side of the conductor plate 7, are circumferentially formed on the underside of the carrier plate 12.

(19) The housing 9, which is preferably made from metal, has an annular shape and comprises an upward facing annular flange 8a, which continues in a further annular flange 8b.

(20) The conductor plate 7 is fastened to this annular flange 8b.

(21) On the one front side, a fastening plate 10 with hole-shaped receptacles is provided on the housing 9 so that the housing 9 can be mounted to an associated mounting surface.

(22) FIG. 3 shows the detail of the section from FIG. 2. It can be seen that several components 11 are arranged on the conductor plate 7, which extend in the direction of the underside of the transmission 2 located above it.

(23) A plurality of transmission gears 14, 15 is present, which are described in further detail on the basis of the following drawings.

(24) FIG. 4 shows a perspective view of the conductor plate 7. It can be seen that three Hall sensors 16a, b, and c are offset from each other at a reciprocal distance and combined with the corresponding electronic components, which are all identified with the reference sign 11.

(25) A connector 17 may be arranged on the conductor plate 7 as well.

(26) FIG. 1 also shows that axle receivers 13 are present in the carrier plate 12 for the axles of the transmission, which will be described below, in which the axles are rotatably embedded.

(27) FIG. 5 shows an optional embodiment in comparison with FIG. 10, wherein distance-maintaining spacer rings 18 are provided to keep the distance between the permanent magnets 22 that are embedded in the magnetic transmission gears 14 and the surface of the corresponding Hall sensors 16a, 16b, and 16c, which preferably fully surround the respective Hall sensor and are a little higher in their axial extension than the surface of the respective Hall sensor 16 so as to form a precisely defined distance.

(28) The respective permanent magnet 22 is then mounted on the surface of the spacer ring 18.

(29) It will be shown later, cf. FIG. 10, that the spacer rings 18 may be completely left out as well and a precise distance may be established between the respective permanent magnets 22 and the Hall sensor 16 by other measures according to the independent claim 1, and therefore the friction-increasing spacer rings 18 may be foregone.

(30) FIG. 6 shows the underside of the carrier plate 12. It can be seen that a specified number of the first type of axles 19a is injected into the assigned axle receivers 13, and they are therefore positioned in a rotatably fixed manner so that they cannot be displaced or buckle.

(31) There are shorter axles 19b as well, which are used to position the intermediate rings of the transmission.

(32) FIG. 7 shows the transmission design where a drive gear 21 with a drive pinion 28, which is connected to the shaft 4 in a rotatably fixed manner, cogs (cf. FIG. 11).

(33) The drive gear 21 acts like a gear reduction 1:16 on a transmission gear 20, which itself consists of a drive gear and a gear with a greater diameter.

(34) The greater gear in the transmission gear 20 cogs with a smaller drive pinion, which is not shown in further detail, which is connected to the respective transmission gear 14a, 14b, 14c in a rotatably fixed manner.

(35) This way, a lower drive level 56 (cf. FIG. 10) is formed by the transmission gears 20 acting as connecting links. At a distance 58 from it, there is an upper drive level 57, which is formed by the individual magnetic transmission gears 14a, 14b, 14c.

(36) With respect to FIGS. 6 and 7, it should be added that the axles 19b, which are longer in their axial length, are used to mount the transmission gears 20 while the shorter axles 19a are made from a magnetically conductive material and are used to mount the magnetic transmission gears 14.

(37) This way, a 1:4096 reduction is achieved between the drive gear 21 and the last magnetic transmission gear 14c.

(38) FIGS. 8 and 9 show the particularly easy assembly of the transmission 2 on the conductor plate 7. It can be seen that, in the first embodiment, which works with spacer rings 18, the reduction gear 2 is snapped onto the conductor plate 7 in the direction of the arrow 24. There are retaining lugs 23, which support themselves on the surface of the conductor plate and are screwed together with the same by means of screwing elements that are not shown in further detail. The result is an overall design as shown in FIG. 9.

(39) FIG. 8 also shows the different transmission levels of the gears 14 and 20 in the form of the representation of levels 56 and 57.

(40) FIG. 10 shows the second embodiment where the distance-maintaining spacer rings 18 are not used, but instead, the technical teaching according to the independent claim 1 is used for a precise, play-free mounting of the magnetic transmission gears 14.

(41) FIG. 10 shows an intermediate gear 26, which is mounted in a short axle 19c.

(42) A total of three intermediate gears 26 are present, and the corresponding axle stubs 19c are shown in FIG. 6.

(43) What is important about this embodiment is that the friction-increasing spacer rings 18 are not necessary and a snapping mechanism, which is under a magnetic holding force, is provided.

(44) The axle 19a is mounted in the carrier plate 12 in the overmold 52 in a rotatably fixed and displacement-protected manner and guided along a longer axial length so that it is mounted without any play.

(45) The front free end of the axle 19a is provided with an annular groove, the diameter of which decreases, which engages with a ring set 27 with an increasing diameter in the inner bore of the transmission gear 14.

(46) The transmission gear is therefore placed on the free axle stub so that the annular groove 25 positively engages with the ring set 27 of the transmission 14, thus providing a pivot bearing.

(47) Since such a pivot bearing is always, however, associated with a certain degree of axial play, an axial magnetic pretension is provided.

(48) To this purpose, the permanent magnet 22 embedded in the material of the transmission gear in the area of an overmold 48 now exerts a magnetic force on the axle 19a consisting of magnetic material with its embedding front side in the direction of the arrow 50 so that a tensile force is created that acts in the direction of the arrow 49.

(49) This way, the transmission gear 14 is pulled upward in the direction of the arrow 55 against the axle 19a and, with a respective annual projection arranged on the front side, comes in contact with a respective stop surface in the carrier plate 12.

(50) This results in a play-free, axial displacement safeguard, which, even if the entire assembly has a longer service life, always leads to a constant and unchangeable distance 54 from the Hall sensor 16 below.

(51) In the drawing shown in FIG. 10, the magnetically sensitive surface is only drawn in as a reference line 53 of a Hall sensor 16 that is not realistically shown.

(52) FIG. 11 shows the so-called one-level design of the multi-turn rotary encoder 1 according to the invention. It shows that a drive pinion 28 is connected with the shaft 4 in a rotatably fixed manner, which engages with the drive gear 21 of the transmission 2.

(53) It can also be seen that a disk flange 29 is connected with the shaft 4 in a rotatably fixed manner on which an optically acting code carrier 31 is mounted.

(54) A lighting unit 32 is arranged below the code carrier 31. It directs a beam of light in the direction of the arrow 33 against the underside of the code carrier 31, which is penetrated by this beam of light and which receives the corresponding measurement signal from an optically sensitive single-turn scanner 34.

(55) The single-turn scanner 34 is therefore arranged on the underside of the conductor plate 7 while the corresponding Hall sensors 16a, 16b, 16c are arranged on the upper side of the conductor plate.

(56) The shaft 4 furthermore has a ball bearing 30. Consequently, it is a one-level design because the conductor plate 7 is the only conductor plate used.

(57) In contrast, FIG. 12 shows a multi-turn rotary encoder 1a, which has a two-level design, characterized in that the conductor plate 7 with the components 11 mounted on it is present and that only one single-turn scanning function is present on the underside of the conductor plate, as shown in FIG. 11, while the magnetic scanning has now been moved to the upper side of the transmission 2.

(58) The same parts are identified with the same reference signs. It can be seen that the reduction gear was basically turned by 180 degrees and the permanent magnets 22, which had previously pointed downward, now point upward in the direction of the underside of a further conductor plate 35 forming a cover plate, at the underside of which the Hall sensors 16a, 16b, 16c are arranged.

(59) By arranging two conductor plates 7, 35 opposite each other, a compact design can be achieved as well, and the second conductor plate 35 provides the opportunity to arrange further space-occupying components in the space created in the direction of the reduction gear, which was not possible in the first-referenced embodiment according to FIG. 11.

(60) It may also be provided that the first conductor plate 7 is connected with the second conductor plate 35 via flexible conductor paths, which are not shown in the representation according to FIG. 12.

(61) An intermediate plate 36 may furthermore be provided between the underside of the conductor plate 35 and the upper side of the transmission, which adjusts the defined distance between the conductor plate 35 and the permanent magnets 22 of the transmission 2.

(62) Consequently, the intermediate plate 36 may take over the function of the distance-maintaining rings 18.

(63) Naturally, this embodiment also provides, within the meaning of the description of FIG. 10, that a magnetically pretensioned snapping mechanism is present between the respective axles 19a and the corresponding permanent magnets 22.

(64) In this case, the intermediate plate 36 is not necessary.

(65) FIG. 13 shows a preferred embodiment of an evaluation circuit. What is important here is that each magnetic transmission gear and the permanent magnet 22 embedded in it is associated with a sensor 37a, 37b, 37c.

(66) The sensor consists of a matrix of Hall sensors 16a, 16b, 16c with each Hall sensor essentially consisting of four Hall sensors arranged at a distance from each other.

(67) It is also possible to provide a single Hall sensor instead of a matrix of a plurality of Hall sensors.

(68) What is important about the evaluation circuit according to FIG. 13 is that initially a clock signal is fed in parallel to all sensors 37 via the clock line 39, and the data input 42a at the first sensor is grounded, and now the first reduction stage for the first transmission gear 14a is provided in the first sensor.

(69) The sensors 37a, b, c are therefore arranged in cascading steps 38a, 38b, 38c, and the respective output signal at the data output 41a of the first sensor 37a is transmitted to the first data input 42b of the second step 38b according to the invention.

(70) The data output 41b in the second step 38b is transmitted via the data output line 40b to the input 42c of the third step 38c, and its data output 41c forms a combined data word, which consists of the single-turn data word and the multi-turn data word.

(71) All data words are arranged serially and nested in each other.

(72) The multi-turn code word thus created in the data output line 40c is transmitted in a serial form to the single-turn signal processing 43 in FIG. 14.

(73) The module shown there forms the single-turn position word and forms, together with the multi-turn position, an overall position word at the data output 46, which consists of the single-turn value and the multi-turn value.

(74) A superordinate master, which is not shown in any drawing, requests, via the clock line 45, the issuance of the combined data word from the signal processing 43 on the data output 46.

(75) A memory 44 is present as well, with which the signal processing 43 can be configured.

(76) Overall, the Daisy chain data processing offers the advantage that in the evaluation circuit according to FIGS. 13 and 14, in the region of the sensors 37a, b, c, the digital evaluations take place at the same time. This means that external separate components that require extra work and space are not necessary.

(77) The programming effort is minimized as well because the individual sensors can be programmed with the digital means.

EXPLANATION OF THE DRAWINGS

(78) 1, 1a Multi-turn rotary encoder 2 Reduction gear 3 Recess 4 Shaft 5 Lug 6 Support 7 Conductor plate 8 Annular flange a, b 9 Housing 10 Fastening plate 11 Components (from 7) 12 Carrier plate 13 Axle receiver 14 Magnetic transmission gear 15 Gear 16 Hall sensor a, b, c 17 Connector 18 Spacer ring 19 Axle a, b 20 Transmission gear 21 Drive gear 22 Permanent magnet 23 Retaining lug 24 Direction of the arrow 25 Annular groove 26 Intermediate gear 27 Ring set 28 Drive pinion (from 4) 29 Disk flange 30 Ball bearing 31 Optic code carrier 32 Lighting unit 33 Direction of the arrow 34 Single-turn scanning 35 Conductor plate (second plate) 36 Intermediate plate 37 Sensor a, b, c 38 Step a, b, c 39 Clock line 40 Data output line a, b, c 41 Data output a, b, c 42 Data input a, b, c 43 Signal processing 44 Memory 45 Clock line (field bus) 46 Data output (multi-value) 47 48 Overmolding (from 22) 49 Direction of the arrow 50 Direction of the arrow 51 Stop surface 52 Overmolding 53 Reference line (16) 54 Distance 55 Direction of the arrow 56 Lower drive level (from 2) 57 Upper drive level 58 Distance