Sensor device with compact magnet, especially for coupling devices for commercial vehicles

Abstract

Clutch device (K) for a manual transmission of a commercial vehicle, comprising a sensor device (S), comprising: a magnet (3) which is attached to a piston (2) which can be moved in a piston housing (1); at least two sensors (5a, 5b) which are provided as a cascade in a sensor housing (4) and which are adapted to detect the position of the magnet (3), wherein the sensors (5a, 5b) serve to detect the position of the piston (2), wherein the coupling device further comprises an elastic element (8), which is adapted to press the sensor housing (4) against the piston housing (2).

Description

The present application is concerned with measuring the position of a magnet by a position sensor as applied, for example, to clutch devices for utility vehicles.In commercial vehicles, transmission automation is becoming an increasingly important role, since transmission automation has considerable advantages with regard to fuel consumption and wear minimization compared to manual transmissions.A transmission automation requires, among other things, a clutch actuator with a required position detection so that the current position of the clutch actuator is always detectable.The prior art discloses, for example, the document DE 10 2020 119 185 A1. This document is concerned with a clutch device for a transmission of a commercial vehicle having a clutch actuator, a sensor for detecting the position of the clutch actuator and a sensor stop having a stop surface. The stop surface defines a predetermined position of the sensor in a direction of distance from the clutch actuator. The sensor is held in a fixed position relationship with the sensor stop via an elastic element in the distance direction.Furthermore, the document DE 10 2021 203 731 A1 is known from the prior art. This discloses a displacement measuring device for measuring a position of a piston with respect to a cylinder along an axial direction. The displacement measuring device comprises a first measuring component and a second measuring component, which form a measuring system for measuring a relative position of the first and the second measuring component with respect to one another, which position indicates the position of the piston. The first measurement component is coupled to one of the piston and cylinder parts. The second measurement component is coupled to the other of the piston and cylinder parts. The first measurement component is formed to be movable along the axial direction with respect to the one part of piston and cylinder.A position sensor must detect the position of a working piston, for example a clutch actuator, through an aluminum wall. The sensing magnet can be only a permanent magnet which can be connected to the piston. Various magnetic sensor elements can be used to sense the magnet, for example Hall chips or magnetoinductive sensors (for example based on the PLCD principle). In particular in the case of a clutch actuator, the clutch position, in particular the grinding point, must always be able to be detected very accurately on account of the safety-relevant function of the central release mechanism. The positioning of the displacement sensor therefore plays a considerable role. Due to space reasons, however, only a small, compact magnet can be used--an annular magnet is not necessary for this purpose, for example. Despite this, a precise measurement of the position of the magnet must always be possible.It is therefore an object of the present invention to enable a precise measurement of the position of a displacement sensor, even if only a small, compact magnet can be used.The technical object is achieved by a coupler device with a sensor device according to claim 1.A sensor device according to the invention has: a magnet which is fastened to a piston which is displaceable in a piston housing, and at least two sensors which are provided in a sensor housing as a cascade. The sensors are adapted to detect the position of the magnetIn particular when using small compact magnets, two sensors, for example two Hall sensors, are connected in cascade, so that a more precise and reliable realization of a position sensing is possible, even via a specific displacement of the magnet. A compact transmitter magnet offers space and cost advantages; for this purpose, for example, a smaller amount of rare earths is required, which additionally ensures less environmental pollution.The length of the magnet in the direction of displacement of the piston is 25% to 50% of the maximum displacement of the piston which is to be detected. In other words, the dimension of the magnet in the direction in which the piston is displaced is between one quarter and half of the path which the magnet travels and which is to be detected. The magnet can thus be held compact, yet accurate and precise sensing is possible.A clutch device for a transmission of a commercial vehicle has a sensor device described above. The piston serves as a clutch actuator, the sensor serves for detecting a position of the piston. Thus, the clutch position, in particular the grinding point, can be determined very accurately.Preferably, the coupling device is adapted to detect a movement of the magnet of at least 40 mm. This has the result that even when a small magnet is used, sufficiently accurate position sensing is possible even if a greater displacement, i.e. of 40 mm or more, takes place.Preferably, an elastic element is further provided, which is adapted to press the sensor housing against the piston housing. Thus, a gap between both housings can be adjusted precisely - the position of the sensor housing is then fixed with respect to the piston housing, which increases the accuracy of the position sensing.More preferably, the sensor housing includes at least one first alignment device and the plunger housing includes at least one second alignment device. The at least first alignment device and at least second alignment device are adapted to be engaged with each other. Thus, the sensor housing can be easily positioned on the piston housing. This also increases the accuracy of the position sensing.The sensors are preferably Hall sensors, magnetoresistive sensors, GMR sensors or TMR sensors, further preferably 2D Hall sensors or 3D Hall sensors. Such sensors are particularly well suited for position sensing.Further preferably, at least four sensors are provided in the sensor housing, of which two are arranged in a cascade in each case.In particular for the realization of safety-relevant functions (e.g. ASIL C, corresponding to ISO26262) of a central clutch release, an even more precise position sensing is thus possible.Further preferably, all sensors in the sensor housing can communicate with one another (by means of a corresponding connection, for example by means of cable, bus etc.). This is necessary if a plurality of sensors are used for the position determination of the magnet. Alternatively, a microprocessor can also be present in the sensor housing, which microprocessor is adapted to evaluate signals of all sensors. In this case, the sensors would not have to be connected to one another, but an evaluation is possible directly in the sensor housing. This saves cabling effort outside the sensor housing.The sensor housing further preferably has an electrical interface, preferably a SENT interface or a TBM interface.An SENT interface is common in the commercial vehicle sector, and the SENT protocol is a unidirectional output protocol. Data in safety-relevant fields of application can thus be output at a constant data rate.In a PWM interface, a pure pulse-modulated signal is generated, which is used for information processing.Preferred embodiments of the present invention are explained in more detail below with reference to the enclosed figures. FIG. 1 is a schematic view of a first embodiment of the present invention FIG. 2 is a schematic view of a second embodiment of the present invention FIG. 3 shows a further schematic view, in particular the positioning of the sensor housing on the piston housing. FIG. 4 shows a detail view of a sensor housing from the front. FIG. 5 shows a side view of a sensor housing. FIG. 6 ashows a top view of a sensor housing as it is fastened to a valve housing, wherein here the sensor housing is attached with play with the aid of fastening devices. FIG. 6 bshows a view similar to FIG. 6 a, wherein fixing devices are attached here on the fastening devices so that the sensor housing cannot fall off the valve housing.FIG. 1 shows a schematic view of a sensor device S according to the invention (for example used in a clutch device K). Here, a piston housing 1 can be seen, in which a piston 2 is displaceably mounted. Mounted on the piston 2 is a small, compact magnet 3, in this case a permanent magnet. On the piston housing 1, a second alignment device 7 aand a fourth alignment device 7 bare provided. Engaged therewith are a first alignment device 6a and a third alignment device 6b, respectively, which are connected to a sensor housing 4. Thus, the sensor housing 4 can be fastened to the piston housing 1 accordingly, but is nevertheless detachable. A sensor 5, here for example a Hall sensor, is provided in the sensor housing 4. The movement of the small magnet 3 can thereby be accurately determined. The sensor housing 4 is fastened to a valve housing 9, and an elastic element 8 is stretched therebetween, which presses the sensor housing 4 in the direction of the piston housing 1. The sensor housing 4 is connected to an electronic control unit 10, by means of which the voltage supply and the signal processing are effected.FIG. 2 shows a schematic view of a second embodiment of a sensor device S or coupling device K. Here, two further sensors 5 cand 5 dare provided, these being connected in a second cascade. This serves for even more accurate position sensing. All four sensors 5 a, 5 b, 5 c, 5 dare directly connected to a microprocessor 10, which is provided here directly in the sensor housing 4.FIG. 3 shows a cross-sectional view of a sensor device S or coupling device K according to the invention. details of the fastening of the sensor housing 4 to a further housing, here valve housing 9, are shown in more detail here. Again shown is the piston housing 1, in which the piston 2 is mounted displaceably with the magnet 3.Again shown is the second alignment device 7 aand the fourth alignment device 7 bon the piston housing 1, which are engaged with the first alignment device 6 aand the third alignment device 6 b, respectively, which are connected to a sensor housing 4. Thus, the sensor housing 4 can be fastened to the piston housing 1 accordingly, but is nevertheless detachable.However, the sensor housing 4 is also connected to the valve housing 9. Recesses 12 are present in the sensor housing 4, in each of which recesses a fastening device 11 which is connected to the valve housing 9 can be engaged. With play, fixing devices 13 are furthermore provided on the fastening devices 11 so that the sensor housing 4 cannot fall off the valve housing 9 but is nevertheless mounted thereon with play. A rotation prevention means, consisting of a first rotation prevention section 16 and a second rotation prevention section 17, is schematically indicated here.In FIG. 4, a sensor housing 4 can be seen from the front. On the sensor housing 4 a first projection 4 ais provided, in which the third fastening device 6 bis provided, in this case an elongated hole. The first fastening device 6 ais a bore which is provided with a squeezing rib 14. Furthermore, recesses 12 are also provided, with which the sensor housing can be fastened to a further housing 9 (not shown here). The fixing to the piston is effected by the first fastening device 6 a, here the bore with squeezing ribs 14, and the third fastening device 6 b, here embodied as an elongated hole.FIG. 5 shows a sensor housing 4 from the side. Here, a second projection 15 is also provided, in which an electrical contact 18 is provided. This electrical contact 18 serves, for example, for fastening to the valve housing 9 (not shown here) for the electrical contact of the corresponding connections.In FIG. 6 a) a front view of the sensor housing 4 is shown, which is fastened to the valve housing 9. Here, fastening devices 11 are provided on the valve housing 9, these being in engagement with corresponding recesses 12 of the valve housing 4. Thus, the sensor housing 4 can be fastened to the valve housing 9 with play. Furthermore, the first alignment device 6 a(configured as a bore with squeezing ribs 14) and the third alignment device 6 b(configured as an elongated hole) are shown. This is the fixing to the second alignment device 7 aand the fourth alignment device 7 bto the piston housing 1 (not illustrated here).FIG. 6 b ) furthermore shows that fixing devices 13 are placed on the fastening device 11 (not visible in detail here), so that the sensor housing 4 can no longer fall off the valve housing 9.Despite this, there is play here, i.e. when the valve housing 9 with the sensor housing 4 is displaced in the direction of the piston housing 1 (not shown here), pre-positioning is possible, but there is nevertheless sufficient play that the sensor housing 4 can be placed even more precisely on the piston housing 1 (not shown here).LIST OF REFERENCE CHARACTERSS sensor device K clutch device 1 piston housing 2 piston 3 magnet / permanent magnet 4 sensor housing 4 afirst projection 5 a, 5 b, 5 c, 5 dsensor 6 afirst alignment device 6 bthird alignment device 7 asecond alignment device 7 b fourth alignment device 8 elastic element 9 valve housing 10 electronic control unit / microprocessor 11 fastening device 12 recess 13 fixing device 14 squeezing rib 15 second projection 16 first anti-rotation section (piston) 17 second anti-rotation section (housing) 18 electrical contact / electrical interface

Claims

Clutch device (K) for a gearbox of a commercial vehicle, having a sensor device (S), having: a magnet (3) which is fastened to a piston (2) which is displaceable in a piston housing (1); at least two sensors (5a, 5b) which are provided in a sensor housing (4) as a cascade, which are adapted to detect the position of the magnet (3), the sensors (5a, 5b) serving to detect the position of the piston (2), the clutch device furthermore having an elastic element (8) which is adapted to press the sensor housing (4) against the piston housing (2).Clutch device (K) according to claim 1, wherein the length of the magnet (3) of the sensor device in the displacement direction of the piston (2) is 25% to 50% of the maximum displacement of the piston (2) to be detected.The clutch device (K) according to claim 1, wherein the clutch device is adapted to detect a movement of the magnet (3) of at least 40 mm.Coupling device (K) according to claim 1, wherein the sensor housing (4) comprises at least one first alignment device (6a, 6b), and the piston housing (1) comprises at least one second alignment device (7a, 7b), wherein the at least one first alignment device (6a, 6b) and the at least one second alignment device (7a, 7b) are adapted to be engaged with each other.Clutch device (K) according to one of Claims 1 to 4, wherein the sensors (5a, 5b) are Hall sensors, magnetoresistive sensors, GMR sensors or TMR sensors, preferably 2D Hall sensors or 3D Hall sensors.Clutch device (K) according to one of Claims 1 to 5, wherein at least four sensors (5a, 5b, 5c, 5d) are provided, of which two are each arranged in a cascade.Clutch device (K) according to one of claims 1 to 6, wherein the sensors (5a, 5b; optionally 5c, 5d) are adapted to be able to communicate with each other.Clutch device (K) according to one of Claims 1 to 6, wherein a microprocessor (10) is furthermore provided in the sensor housing (4), which microprocessor is adapted to evaluate signals of the sensors (5a, 5b; optionally 5c, 5d).Clutch device (K) according to one of Claims 1 to 8, wherein the sensor housing has an electrical interface (18), preferably a SENT interface or PWM interface.Clutch device (K) according to one of Claims 1 to 9, wherein the piston (2) serves as a clutch actuator.

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