Sensor target carrier ring for a piston-cylinder arrangement

Abstract

Sensor target carrier ring (1) for a piston-cylinder assembly (2), wherein the piston-cylinder assembly (2) comprises a hollow cylindrical cylinder (4) designed as a housing (3) and a piston (6) movable in the cylinder (4) along an axial direction (5), wherein a sensor (7) for detecting a sensor target (8) arranged on the housing (3) and the sensor target carrier ring (1) are arranged on the piston (6); wherein the sensor target carrier ring (1) comprises a holder (9) with the sensor target (8), wherein the holder (9) is made of plastic and the sensor target (8) is embedded in the plastic; wherein the sensor target carrier ring (1) comprises a reinforcing ring (10) with at least one fastening element (11), wherein the reinforcing ring (10) is connected to the holder (9) via a plastic deformation of the at least one fastening element (11).

Description

The present invention relates to a sensor target carrier ring for a piston-cylinder assembly. The piston-cylinder assembly is, in particular, a component of a clutch actuation device for a friction clutch. The friction clutch can be actuated (disengaged or engaged) by moving the piston of the piston-cylinder assembly. A piston-cylinder assembly comprises, in particular, a hollow cylindrical cylinder designed as a housing and a piston movable within the cylinder along an axial direction. A sensor (e.g., a Hall sensor) for detecting a sensor target (e.g., a magnet) arranged on the sensor target carrier ring is located on the housing, and the sensor target carrier ring is located on the piston. The sensor target carrier ring includes a holder with the sensor target. A piston-cylinder arrangement is known from EP 1 898 111 A2. Furthermore, a piston-cylinder arrangement is known from the subsequently published DE 10 2016 124 269 A1, wherein the sensor target is received in a holder of the sensor target carrier ring via detent elements. In this arrangement, at least after a certain operating time, play can occur between the detent elements and the sensor target, which can distort the sensor's measured values. High rigidity of the sensor target carrier ring is important to ensure the most stable position possible of the sensor target relative to the sensor. For this purpose, it would be desirable to reinforce the sensor target carrier ring, for example, with a metallic reinforcement ring. Solutions are known in which the reinforcement ring is cast into a plastic, so that the reinforcement ring and the sensor target are integrally connected. However, it can be problematic to arrange the already magnetized sensor target together with the metallic reinforcement ring in a single injection mold. Magnetizing the sensor target after injection molding can have an undesirable effect on the metallic reinforcement ring. Subsequent insertion of the sensor target into the holder, for example, using locking elements, may lead to undesirable play between the locking elements and the sensor target. The sensor target is, for example, a neodymium-iron-boron, SmCo, AlNiCo, or ferrite magnet. The sensor is, for example, a Hall sensor. Furthermore, DE 10 2015 211 831 A1 discloses a release system for a clutch actuation system with a sensor target carrier ring, wherein the sensor target carrier ring comprises a reinforcing ring and a holder, the reinforcing ring being connected to the holder by a plastic deformation of a fastening element. According to that document, the fastening elements are arranged on or formed from the holder. DE 102 42 841 A1 describes a release bearing for a clutch with a magnetic sensor, wherein the magnet is arranged in a holder, the magnet being designed as an insert around which the holder is at least partially formed. The object of the invention is to at least partially solve the problems described with reference to the prior art and in particular to provide a sensor target carrier ring in which the sensor target is securely and without play received and which itself has a high stiffness. This problem is solved with a sensor target carrier ring according to the features of the independent claim. Further advantageous embodiments of the invention are specified in the dependent claims. It should be noted that the features listed individually in the dependent claims can be combined with one another in a technologically meaningful manner and define further embodiments of the invention. In addition, the features specified in the claims are further specified and explained in the description, which also presents further preferred embodiments of the invention. The invention relates to a sensor target carrier ring for a piston-cylinder assembly. The piston-cylinder assembly is, in particular, a component of a clutch actuation device for a friction clutch. The piston-cylinder assembly comprises a hollow cylindrical cylinder designed as a housing and a piston movable along an axial direction within the cylinder. A sensor for detecting a sensor target arranged on the sensor target carrier ring is located on the housing, and the sensor target carrier ring is located on the piston. The sensor target carrier ring includes a holder with the sensor target, wherein the holder is made of plastic and the sensor target is embedded in the plastic. The sensor target carrier ring includes a reinforcing ring with at least one fastening element, wherein the reinforcing ring is connected to the holder by means of a plastic deformation of the at least one fastening element. A friction clutch is typically a single-plate dry clutch or a dual clutch. Such friction clutches serve to interrupt the torque flow from a drive motor to the drivetrain of a motor vehicle. The friction clutch can be engaged and / or disengaged by a clutch actuation device to activate and / or deactivate the torque flow from a drive motor to the drivetrain of the motor vehicle. The clutch actuation device can be, in particular, a master cylinder (for example, connected to a clutch pedal) or a slave cylinder. The slave cylinder can be directly connected to the friction clutch. The piston-cylinder assembly comprises a housing in which a piston is movably arranged. In the case of a master cylinder, the piston can build up pressure in a pressure chamber for a hydraulic fluid, which, via a hydraulic line, moves the piston of a slave cylinder. In the case of a slave cylinder, the piston can act directly or indirectly on the friction clutch to actuate the friction clutch. The piston is firmly connected to the sensor target via the sensor target carrier ring, so that the sensor target can be moved along the axial direction with the piston in the housing in a way that remains as permanently unchanged as possible. The sensor target is, in particular, a magnet, which can be, for example, a neodymium-iron-bore magnet or an SmCo, AlNiCo, or ferrite magnet. The magnet interacts with the sensor so that the position or stroke of the piston within the housing of the piston-cylinder assembly can be detected. The magnet generates a magnetic field, which is detected by the sensor. The sensor's switching point is determined by a threshold value of the measured magnetic flux density. Such a sensor uses the so-called Hall effect to measure magnetic fields. By moving the magnet and piston along the axial direction, the sensor can detect a corresponding change in the magnetic field in its vicinity. This change causes a change in the Hall voltage. However, a change in the Hall voltage can only be determined above a predetermined minimum magnetic flux density. In particular, the holder is designed in a ring shape, with the holder, piston and reinforcing ring arranged coaxially to each other. In particular, the holder and the reinforcement ring each extend in a ring shape, with the sensor target being spaced apart in a radial direction and arranged outside the reinforcement ring. Preferably, the reinforcing ring comprises a metallic material or is made exclusively of a metallic material. In particular, the holder has a receptacle for the at least one fastening element, wherein the receptacle for the at least one fastening element forms a stop against a circumferential direction. Rotation of the holder relative to the reinforcing ring is therefore no longer possible, or at least restricted, at least after the forming of the at least one fastening element. Preferably, the reinforcing ring comprises a plurality of fastening elements spaced apart from one another along a circumferential direction. In particular, the holder comprises a plurality of receptacles, each receptacle preferably interacting with a fastening element. A further method for manufacturing the described sensor target carrier ring is proposed, comprising at least the following steps: a) providing a holder with a sensor target, wherein the holder is made of plastic and the sensor target is embedded in the plastic; b) providing a reinforcement ring; c) arranging the holder and reinforcement ring; d) plastically forming at least one fastening element for connecting the holder and reinforcement ring. Plastic forming includes, in particular, bending the at least one fastening element. In particular, the holder and the reinforcing ring are connected to each other without play according to step d). A further piston-cylinder arrangement is proposed, wherein the piston-cylinder arrangement comprises a hollow cylindrical cylinder designed as a housing, a piston movable in the cylinder along an axial direction, and the sensor target carrier ring already described, which is designed as described and / or manufactured by the described method, wherein a sensor for detecting a sensor target arranged on the sensor target carrier ring is arranged on the housing and the sensor target carrier ring is arranged on the piston. A clutch actuation device for a friction clutch is further proposed, wherein the clutch actuation device comprises the piston-cylinder arrangement already described as well as a release bearing, wherein a friction clutch can be actuated via the release bearing. The statements regarding the sensor target carrier ring apply equally to the piston-cylinder arrangement, the clutch actuation device and the method, and vice versa. It should be noted as a precaution that the numerical terms used here ("first", "second", etc.) primarily serve (only) to distinguish between several similar objects, quantities, or processes, and thus do not necessarily dictate any dependency and / or sequence between these objects, quantities, or processes. Should a dependency and / or sequence be required, this is explicitly stated here, or it will be obvious to a person skilled in the art upon studying the specific configuration described. The invention and its technical context are explained in more detail below with reference to the figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and combine them with other components and findings from the present description and / or figures. It should be noted in particular that the figures, and especially the depicted dimensions, are only schematic. The same reference numerals denote the same objects, so that explanations from other figures can be used as a supplement. The figures show: Fig. 1: a clutch actuation device in a side view with a piston-cylinder arrangement in a first position; Fig. 2: the piston-cylinder arrangement according to Fig. 1 in a side view in a second position; and Fig.Fig. 3: a sensor target carrier ring in a first perspective view; Fig. 4: the sensor target carrier ring according to Fig. 3 in a second perspective view; Fig. 5: holder and reinforcing ring of the sensor target carrier ring according to Fig. 3 and in a perspective view; Fig. 6: the sensor target carrier ring according to Fig. 5 in a perspective view according to step c) of the method; Fig. 7: the sensor target carrier ring according to Fig. 6 in a perspective view according to step d) of the method; Fig. 8: the sensor target carrier ring according to Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. 7 in a perspective view in section; and Fig. 9: the sensor target carrier ring according to Fig. 8 in a side view in section. Fig. 1 shows a clutch actuation device 16 in a side view with a piston-cylinder assembly 2 in a first position. Fig. 2 shows the piston-cylinder assembly 2 from Fig. 1 in a side view in a second position. Figs. 1 and 2 are described together below. The piston-cylinder assembly 2 comprises a hollow cylindrical cylinder 4 designed as a housing 3, a piston 6 movable within the cylinder 4 along an axial direction 5 between a first position (Fig. 1) and a second position (Fig. 2), and a sensor target carrier ring 1. A sensor 7 is arranged on the housing 3 for detecting a sensor target 8 located on the sensor target carrier ring 1, and the sensor target carrier ring 1 is arranged on the piston 6. The clutch actuation device 16 comprises the piston-cylinder arrangement 2 and a release bearing 18, wherein a friction clutch 17 can be actuated via the release bearing 18. Fig. 3 shows a sensor target carrier ring 1 in a first perspective view. Fig. 4 shows the sensor target carrier ring 1 from Fig. 3 in a second perspective view. Figs. 3 and 4 are described together below. The sensor target carrier ring 1 comprises a holder 9 with the sensor target 8, wherein the holder 9 is made of plastic and the sensor target 8 is embedded in the plastic. The sensor target carrier ring 1 comprises a reinforcement ring 10 with a plurality of fastening elements 11, wherein the reinforcement ring 10 is connected to the holder 9 by plastic deformation of the fastening elements 11. The holder 9 is annular in design, with the holder 9, piston 6, and reinforcing ring 1 arranged coaxially to each other. The holder 9 and the reinforcing ring 10 each extend annularly, with the sensor target 8 spaced radially 12 apart and located outside the reinforcing ring 10. The holder 9 has receptacles 13 for each fastening element 11, with each receptacle 13 forming a stop 14 against a circumferential direction 15 for each fastening element 11. Rotation of the holder 9 relative to the reinforcing ring 10 is therefore no longer possible, at least after the fastening elements 11 have been formed. Fig. 5 shows holder 9 and reinforcement ring 10 of the sensor target carrier ring 1 according to Fig. 3 and in a perspective view and according to steps a) and b) of the method. Fig. 6 shows the sensor target carrier ring 1 according to Fig. 5 in a perspective view according to step c) of the method, wherein the fastening elements 11 are arranged in axial direction 5 aligned with the receptacles 13. Fig. 7 shows the sensor target carrier ring 1 according to Fig. 6 in a perspective view according to step d) of the method. In this step, the fastening elements 11 for connecting the holder 9 and the reinforcing ring 10 are plastically deformed. Fig. 8 shows the sensor target carrier ring 1 according to Figs. 3, 4, 5, 6 to 7 in a perspective section. Fig. 9 shows the sensor target carrier ring 1 according to Fig. 8 in a side section. Figs. 8 and 9 are described together below. The sensor target 8 is clearly completely enclosed by the material of the holder 9 and arranged within the holder 9. The reinforcing ring 10 and the holder 9 are connected to each other via the fastening elements 11. Reference symbol list 1 Sensor target carrier ring 2 Piston-cylinder assembly 3 Housing 4 Cylinder 5 Axial direction 6 Piston 7 Sensor 8 Sensor target 9 Holder 10 Reinforcing ring 11 Fastening element 12 Radial direction 13 Receptacle 14 Stop 15 Circumferential direction 16 Clutch actuation device 17 Friction clutch 18 Release bearing

Claims

Sensor target carrier ring (1) for a piston-cylinder assembly (2), wherein the piston-cylinder assembly (2) comprises a hollow cylindrical cylinder (4) designed as a housing (3) and a piston (6) movable in the cylinder (4) along an axial direction (5), wherein a sensor (7) for detecting a sensor target (8) arranged on the housing (3) and the sensor target carrier ring (1) are arranged on the piston (6); wherein the sensor target carrier ring (1) comprises a holder (9) with the sensor target (8), wherein the holder (9) is made of plastic and the sensor target (8) is embedded in the plastic; wherein the sensor target carrier ring (1) comprises a reinforcing ring (10) with at least one fastening element (11), wherein the reinforcing ring (10) is connected to the holder (9) via a plastic deformation of the at least one fastening element (11). Sensor target carrier ring (1) according to claim 1, wherein the holder (9) and the reinforcement ring (10) each extend in a ring shape, wherein the sensor target (8) is spaced apart in a radial direction (12) and is arranged outside of the reinforcement ring (10). Sensor target carrier ring (1) according to one of the preceding claims, wherein the reinforcement ring (10) comprises a metallic material. Sensor target carrier ring (1) according to one of the preceding claims, wherein the holder (9) has a receptacle (13) for the at least one fastening element (11), wherein the receptacle (13) for the at least one fastening element (11) forms a stop (14) against a circumferential direction (15). Sensor target carrier ring (1) according to one of the preceding claims, wherein the reinforcement ring (10) comprises a plurality of fastening elements (11) which are spaced apart from one another along a circumferential direction (15). Method for manufacturing a sensor target carrier ring (1) according to one of the preceding claims, comprising at least the following steps: a) providing a holder (9) with a sensor target (8), wherein the holder (9) is made of plastic and the sensor target (8) is embedded in the plastic; b) providing a reinforcement ring (10); c) arranging the holder (9) and the reinforcement ring (10) relative to each other; d) plastically forming at least one fastening element (11) for connecting the holder (9) and the reinforcement ring (10). Piston-cylinder assembly (2), wherein the piston-cylinder assembly (2) comprises a hollow cylindrical cylinder (4) designed as a housing (3), a piston (6) movable in the cylinder (4) along an axial direction (5), and a sensor target carrier ring (1) designed according to any one of the preceding claims 1 to 5 or manufactured by the method according to claim 6, wherein a sensor (7) for detecting a sensor target (8) arranged on the housing (3) and the sensor target carrier ring (1) are arranged on the piston (6). Clutch actuation device (16) for a friction clutch (17), comprising at least a piston-cylinder arrangement (2) according to claim 7 and a release bearing (18), wherein a friction clutch (17) can be actuated via the release bearing (18).

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