DE20315735U1 - Axial position sensing device for piston in hydraulic clutch in motor vehicle, has flux-conducting element extending over range of relative axial positions of permanent magnet - Google Patents

Abstract

A magnetic signaling element (18) is arranged on one component, while a magnetic flux sensitive sensor (20) is arranged on another component. The sensor is provided with a fixed, flux-conducting element (22) which extends at least over the range of axial relative positions of the signaling element with respect to the sensor. The signal element is a permanent magnet, such as an annular magnet. The sensor is a Hall sensor. The flux-conducting element comprises sheet metal such as dynamo sheet.

Description

The invention relates to a Device for sensing the axial position of one of two relative components movable relative to one another with respect to the other component according to the preamble of Protection claim 1. In particular, the invention relates to a Device for sensing the axial position of a piston with respect to a cylinder housing Master or slave cylinders for a hydraulic clutch control for motor vehicles, how they are used en masse in the automotive industry.

A conventional hydraulic clutch control for motor vehicles has connected to an expansion tank filled with hydraulic fluid Master cylinder, for example, via a clutch pedal or an electric motor drive can be operated. The master cylinder is over a pressure line hydraulically connected to a slave cylinder, so that the by depressing the clutch pedal or shifting electromotive of the master cylinder piston in the master cylinder generated pressure over the Liquid column in the Pressure line is transferable to the slave cylinder. As a result becomes the release bearing the clutch over an actuating force is applied to the slave cylinder piston, um over a release mechanism the clutch pressure plate from the clutch drive plate and thus to separate the engine from the gearbox of the motor vehicle. Also are hydraulic clutch actuation known where the release mechanism the coupling of an actuating or slave cylinder operatively connected to it actuated can, in turn, be over a hydraulic servo circuit is controlled.

In the case of such hydraulic clutch actuations for motor vehicles, it has already been proposed in the prior art to sense the position of the piston of the master or slave cylinder by means of suitable mechanical, electrical or magnetic devices (for example US 4,705,151 . DE 41 20 643 A1 ) to indirectly infer the position of the clutch pressure plate. On the one hand, such a sensation enables a statement to be made about the wear condition of the clutch. On the other hand, the engagement or disengagement state of the clutch can be determined, so that, for example in the case of automated friction clutches, the clutch actuation can be controlled automatically to the desired extent. Finally, the results of the sensing can also be used for safety precautions in the operation of the motor vehicle, for example that the motor vehicle can only be started when the clutch pedal is depressed.

In this context, the DE 199 15 832 A1 a master cylinder, which has a piston arranged longitudinally displaceably in a housing. An annular groove is formed on the piston and is used to hold an annular magnet. On the housing of the master cylinder there is a receiving part in which two Hall switches, an associated evaluation electronics and a connection contact part are arranged. By means of the Hall switch, the position of the ring magnet and thus the position of the piston are detected through the wall of the cylinder housing, whereupon the corresponding switching signal is processed by the evaluation electronics and then released to the outside via the connection contact part for further processing.

The one described there, a ring magnet and position transmitter comprising two Hall switches is only in able to detect the respective end positions of the piston. Intermediate positions or the way of the piston, however, cannot who captured the but what is required if, for example, an exact statement about the wear state the clutch or automatic control of the Disengagement or engagement movement should be done.

The same applies to that from the DE 100 53 995 A1 known position transmitter on a tandem master cylinder of a motor vehicle brake system, which has a housing-side Hall element which interacts with a piston-side magnetic metal pin in order to emit a signal, for example, for actuating a brake light at a specific piston position.

Finally, the generic article "Non-contact, wear-free displacement sensors in clutch and brake systems" by Houben, Hans; Marto, Arno; Wagner, Klaus; Gebert, Stefan and Wöhner, Steffen in ATZ 12/2002, year 104 , Pages 1076 to 1081, a sensor device for clutch cylinders in particular is known, which has a magnetic flux-sensitive sensor arranged in the form of a Hall sensor on the cylinder housing, which cooperates with a magnetic signal element arranged on the piston in the form of a rod-shaped permanent magnet in order to adjust the axial relative position of the permanent magnet to the Hall sensor and thus to detect that of the piston to the cylinder housing.

The sensor device disclosed there is able to detect any position of the piston with respect to the cylinder housing or the path of the piston. According to this prior art, however, a long bar magnet is to be provided for this purpose, which extends over the entire area to be detected from axial relative positions of the piston to the cylinder housing through the piston. This requires a relatively large axial installation space in the piston for accommodating the bar magnet, which can also lead to an undesirable increase in the overall length of the cylinder. In addition, the mechanical stability of the bar magnet must be given special attention so that it does not break, for example, when the bar magnet is installed in the piston. Already so furthermore, the bar magnet must not be made too thin. A thicker design of the bar magnet, on the other hand, undesirably increases the radial space for accommodating the bar magnet in the piston, not to mention the associated higher costs for the bar magnet, which are also undesirable in view of the mass use of such sensor devices.

The invention is in contrast Task based, if possible simply constructed device for sensing the axial position one of two components that can be moved relative to one another with respect to the other component, in particular a piston with respect to a cylinder housing of an encoder or slave cylinder for a hydraulic clutch control for motor vehicles to create, by means of which device with the smallest possible space requirement for the Device any axial relative positions between those involved Components or their relative travel can / can be detected.

This task is covered by the protection claim 1 specified features solved. Advantageous or appropriate further training The invention is the subject of claims 2 to 15.

According to the invention in a device for Sensing the axial position of one of two relative to each other movable components with respect to the another component, in particular a piston with respect to a cylinder housing Master or slave cylinders for a hydraulic clutch control for motor vehicles, which device a magnetic signal element arranged on the one component and at least one magnetic flux sensitive sensor arranged on the other component has, by means of which the axial relative position of the magnetic Signal element for magnetic flux sensitive Detectable sensor is sensitive to magnetic flux Sensor at least one regarding of the magnetic flux sensitive Sensor's fixed flow guide assigned, which is at least on the other component Area to be detected from relative axial positions of the magnetic Signal element for magnetic flux sensitive Sensor extends.

The sensor assigned to the magnetic flux sensitive in terms of of the magnetic flux sensitive Sensor immobile flow guide the sensor device according to the invention serves as a bundle the field lines of the magnetic field of the magnetic signal element, so that relatively high field strengths H in the flow guide result. In other words, it occurs in the flow guide a concentration of the magnetic flux Φ, its density, i.e. the magnetic flux density B by means of the magnetic flux sensitive Sensor can be sensed. The closer the magnetic signal element when moving along the flow guide at a measuring point Flow guide comes where the magnetic flux density B in the flow guide by means of the magnetic flux sensitive sensor is sensed, the higher is the sensed magnetic flux density B.

If, for example, a Hall sensor with a Hall element made of silicon, for example, is used as a sensor sensitive to magnetic flux, which is preferred because the associated evaluation electronics can be integrated in the semiconductor production in a simple and therefore inexpensive manner, the magnetic signal element bundled by the flux guide element results from the magnetic signal element on the Hall element through which an electrical current flows to deflect the charge carriers in the Hall element. This displacement of the charge carriers in the Hall element creates potential differences on the current profile through the Hall element parallel electrodes, at which these potential differences can be tapped as a transverse or Hall voltage U _H. At a constant current I of the current flowing through the Hall element, this Hall voltage U _H is directly proportional to the magnetic flux density B in the flux guide element.

From the above it follows that at the sensor device according to the invention by means of of the magnetic flux sensitive Sensor's magnetic flux density B in the flow guide can be sensed, which in turn is a measure of the axial distance between the magnetic signal element and the magnetic flux sensitive sensor, So that the axial relative positions of the magnetic signal element to the magnetic flux sensitive Sensor continuously detected can be or, in other words, here a detection of the relative path possible with only a few components. The configuration according to the invention allows this the sensor device the use of a compared to the generic state technology small magnets that have a very short axial length can and not over the entire range of axial relative positions to be recorded must extend between the components involved. Those in the generic class long bar magnets provided for by the technology are dispensable as a result, so that too the associated disadvantages can be avoided.

The fact that, in the sensor device according to the invention, the flux guide element on the other component extends at least over the area to be detected from axial relative positions of the magnetic signal element to the sensor sensitive to magnetic flux is conducive to obtaining clear sensor signals. This is because there is thus always an axial overlap of the signal element and flux guide element in the measuring range of the sensor device, which in a simple manner prevents such a change of sign of the detected magnetic field that would occur if the magnetic signal element in the measuring range of the sensor device relative to the magnetflu ß sensitive sensor could move in the axial direction beyond the Flußleit element. In other words, in the sensor device according to the invention, the desired measuring range no longer determines the length of the magnet, as in the generic state of the art, but rather the length of the, among other things, much less expensive flux guide element. As a result, the sensor device according to the invention also opens up fields of application which were previously usually reserved for complex coil-bound, that is to say inductively operating sensor devices, the embodiment of the sensor device according to the invention having the additional advantage that axial relative movements of the signal element to the sensor are reliably detected even at high movement speeds can be.

Another advantage of the sensor device according to the invention can finally be seen in the fact that, in contrast to the generic sensor device with its long bar magnet, it can also be used reliably working on piston-cylinder arrangements, the pistons of which with respect to the cylinder housing depending on the axial piston position by one certain angular amount with respect to the longitudinal axis of the cylinder housing tilted, such as in the DE 43 31 241 A1 described by the applicant.

Basically are for the magnetic Any magnet is conceivable, such as an electromagnet. However, an embodiment is preferred in which the magnetic signal element is a permanent magnet that advantageously no energy supply to build up a magnetic field needed. The permanent magnet is preferably one very compact ring magnet. Other magnet geometries, e.g. a small cuboid or cube-shaped magnet, but are also in accordance with the respective installation requirements conceivable.

In principle, for those sensitive to magnetic flux Sensor any sensor can be used which, as the name suggests, is able to the magnetic flux in the flux guide or a change the same. So could For example, magnetoresistive sensors can also be used. Is preferred however, the use of Hall sensors, which the ones already mentioned above Have advantages. Such Hall sensors are nowadays also programmable Form relatively inexpensive available in the stores. Programmable Hall sensors can in an advantageous manner according to the respective requirements linearization and / or temperature compensation on one Carry out characteristic curve, can be easily adapted to a wide variety of interfaces, yes, possibly even have a teaching function, so that the path characteristic e.g. with regard to the definition of the start and end points, the slope and the reinforcement the signals are optimally adapted to the respective application can.

In an advantageous embodiment the sensor device according to the invention can the flow guide a sheet metal section made of a suitable magnetizable material, like a ferromagnetic dynamo section. In addition to space advantages, which is a sheet metal section, i.e. one in the direction of its thickness Latitude and longitude direction a sheet metal section has a much smaller section of material still the advantage that he according to the respective requirements in terms of geometry the components adapted can be whose relative movement is to be recorded. For example in the preferred here, although not limiting the invention Field of application of the invention, namely the sensing of the axial Position of a piston in relation to of a cylinder housing a master or slave cylinder for hydraulic clutch actuation for motor vehicles, the flow guide in a simple manner by bending the sheet metal section of the curvature of the cylinder housing or the piston, which in turn means in particular that only a small installation space is required for the Sensor device conducive is.

Basically, it is conceivable that the flow guide for example, extends in a direction that matches the direction the axial relative movement of the one component with respect to the other component includes a predetermined angle. Prefers However, an embodiment of the sensor device according to the invention is shown in which is the flow guide essentially in the direction of the axial relative movement of the one Component related of the other component, i.e. lies in the direction of movement, because on the one hand the radial installation space requirement of the sensor device minimized. On the other hand, with such training the evaluation of the sensor device by means of the magnetic flux sensitive Sensor received, for the magnetic flux density B in the flow guide representative Signals easier.

If the magnetic flux sensitive Sensor on the associated flow guide is applied, preferably flat is present, there is a very good level for the flux density B in the flux guide representative Expected signal. Nevertheless, the magnetic flux sensitive Sensor but also according to the respective installation requirements from the flow guide be arranged at a distance, the distance with respect to a flawless signal evaluation should be as small as possible.

The magnetic flux sensitive sensor can advantageously rest on one of the longitudinal ends of the flux guide element on a longitudinal surface of the flux guide element. The end arrangement of the magnetic flux sensitive sensor on the flux guide element has the advantage that the course of the magnetic flux density B in the flux guide element and thus for the relative movement of the magnetic signal element to the flux guide representative signal over the way with an axial approach of the magnetic signal element's to the magnetic flux sensitive sensor steadily increases or decreases when the magnetic signal element moves away from the magnetic flux sensitive sensor in the axial direction, so that the signal is easy to evaluate. With approximately a central arrangement of the magnetic flux sensitive sensor with respect to the flux guide element, which would also be possible in principle, when evaluating the signal it would have to be taken into account in a suitable manner from which side the magnetic signal element approaches the magnetic flux sensitive sensor or to which side the magnetic one approaches Signal element removed from the magnetic flux sensitive sensor, which would complicate the signal evaluation.

As an alternative to an end support of the magnetic flux sensitive Sensor on the flow guide could the magnetic flux sensitive Sensor also useful on a longitudinal side face of the flow guide concern where this is desirable in view of the available space or is required.

In another alternative the sensor device according to the invention can be provided that the flux guide longitudinal is divided into two sections, between which the magnetic flux sensitive Sensor inserted is what makes the magnetic flux sensitive Sensor advantageously directly in the concentrated in the flow guide magnetic flux. Is the magnetic flux sensitive Accordingly, the sensor in the main flow or Area of highest field strength in the flow control element, so this is getting one for the magnetic flux density B in the flow guide representative Signals of high signal strength conducive. Appropriately here also the two sections of the flux guide element each for magnetic flux sensitive Taper the sensor.

If for certain technical applications redundancy of the sensor signals is desirable or necessary is, can two sensitive to magnetic flux Sensors may be provided. With regard to the above, with an end arrangement of the magnetic flux sensitive sensor on the flux guide associated advantages, the arrangement can be compact required Installation space not taken or only slightly enlarged in this way be that the a magnetic flux sensitive sensor at one longitudinal end of the flux guide is while the other sensitive to magnetic flux Sensor at the other longitudinal end of the flow guide is arranged. in principle but is also a parallel arrangement of the two sensitive to magnetic flux Sensors at one end of the flow guide conceivable.

You can also use two flow control elements be provided, which run essentially parallel to each other and between which the magnetic flux sensitive sensor is inserted. In this embodiment of the sensor device, the sensed is for the magnetic one flux density B representative in the flow guide elements Signal compared to a version with only one flow guide weaker. Ensure the two flow control elements but advantageously for a linearization of the over the relative path of the magnetic signal element to the magnetic flux sensitive Sensor applied signal, which simplifies the evaluation of the signal.

In a preferred application of the sensor device according to the invention, the magnetic signal element, preferably a ring magnet, can be attached to a piston of a master or slave cylinder for a hydraulic clutch actuation for motor vehicles, as is known, for example, from DE 202 08 568 U1 is known to the applicant and has already proven itself in series production, while the magnetic flux sensitive sensor with the associated flux guide element is attached to a cylinder housing of the master or slave cylinder. In principle, the arrangement could also be reversed, with the magnetic signal element on the cylinder housing and the magnetic flux sensitive sensor together with the associated flow guide element on the piston. The latter arrangement could, however, again lead to space problems on the piston. In addition, the signal of the magnetic flux-sensitive sensor would have to be discharged from the piston and a power supply to the magnetic-flux-sensitive sensor on the piston would have to be ensured, which would require an essentially undesired line routing to the piston as the moving component.

Finally, in this preferred application of the sensor device according to the invention, the sensor sensitive to magnetic flux and the associated flux guiding element can advantageously be accommodated in a common sensor housing which, as is the case, for example, with DE 201 16 818 U1 the applicant describes - can be attached to the cylinder housing of the master or slave cylinder at a predetermined location.

The invention is illustrated below preferred embodiments with reference to the attached partially schematic drawings explained in more detail. Show •

1 a broken longitudinal sectional view of a master cylinder and a cylinder housing master cylinder for a hydraulic clutch actuation for motor vehicles, on which a device according to the invention for sensing the axial position of the piston with respect to the cylinder housing is mounted, which has a piston-side magnetic signal element and a cylinder-side magnetic flux sensitive sensor with an associated Flow guide element includes

2 a sectional view of the master cylinder 1 according to the section line II-II in 1 .

3 a perspective view of the master cylinder according to 1 .

4 a diagram of the sensor device according to the 1 to 3 , in which the magnetic flux density B [mT] is plotted in the flux guide element over the path s [mm] of the magnetic signal element, which it can travel relative to the magnetic flux sensitive sensor, the magnetic flux sensitive sensor being arranged at the measuring point 41.5 mm on the flux guide element, um to detect the magnetic flux caused therein by the magnetic field of the magnetic signal element,

5 a schematic representation of the sensor device according to the 1 to 3 with a diagram in which an output voltage U output by the magnetic-flux-sensitive sensor is plotted over the path s covered by the magnetic signal element relative to the magnetic-flux-sensitive sensor, which the magnetic-flux-sensitive sensor from the course of the magnetic flux density B according to 4 can win

6 a broken view of the magnetic field of the magnetic signal element of the sensor device according to the 1 to 5 which illustrates how the flux guide element associated with the magnetic flux sensitive sensor bundles the field lines of the magnetic field of the magnetic signal element,

7 a schematic representation of a sensor device according to a further embodiment of the invention with associated voltage-path curve (U = f (s)), the representation of the 5 corresponds,

8th a schematic representation of a variant of the sensor device according to 7 with the associated voltage-path curve (U = f (s)), whereby the representation is again that of 5 corresponds, and

9 a basic representation of a sensor device according to yet another embodiment of the invention with the associated voltage-path curve (U = f (s)), the representation again that of 5 equivalent.

The 1 to 3 show an exemplary master cylinder for a possible application of the present invention 10 for a hydraulic clutch actuation for motor vehicles, the piston shown here in its basic position 12 which is longitudinally displaceable in a cylinder housing 14 is included. With 16 is generally a sensor device for sensing the axial position of the piston 12 regarding the cylinder housing 14 numbered the one here on the piston 12 arranged magnetic signal element in the form of an annular permanent magnet, or ring magnet for short 18 , as well as one here on the cylinder housing l4 arranged magnetic flux sensitive sensor in the form of a Hall sensor 20 has, by means of which the axial relative position of the ring magnet 18 to the Hall sensor 20 can be detected in a manner yet to be described. It is essential that, as will also be explained in more detail below, the Hall sensor 20 at least one regarding the Hall sensor 20 fixed flow guide 22 is assigned, which is located on the cylinder housing 14 at least over the range of axial relative positions of the ring magnet to be detected 18 to the Hall sensor 20 extends.

Like especially that 1 and 3 show, has in the illustrated embodiment made of a non-ferrous metal such as an aluminum alloy cylinder housing 14 at his in 1 left end a pressure connection 24 over which the master cylinder 10 can be connected to a slave cylinder (not shown). The cylinder housing 14 is also like that 2 and 3 it can be seen in the longitudinal direction essentially centrally with two fastening flanges formed on opposite sides 26 for mounting on a pedal bracket (not shown) and one in the 1 and 2 Follow-up connection shown below 28 Mistake. Via the overflow connection 28 can the master cylinder 10 be connected to a trailing tank (not shown). The run-on connection 28 has a trailing channel 30 that in a pressure equalization hole 32 and a trailing hole 34 empties.

On the in the 1 and 2 upper side shows the cylinder housing 14 a flat support surface 36 for a sensor housing made of plastic 38 in which, among other things, the Hall sensor 20 and the associated flow guide 22 are accommodated. On the contact surface 36 of the cylinder housing 14 is the sensor housing 38 in the in the 1 to 3 shown assembled state of the sensor device 16 flat. The attachment of the sensor housing 38 on the cylinder housing 14 takes place in the in the 1 to 3 illustrated embodiment at a predetermined location of the cylinder housing 14 by means of screws 40 , which in associated threaded holes (not shown) of the cylinder housing 14 are screwed in and fastening flanges 42 of the sensor housing 38 reach through and reach behind. The sensor housing could be an alternative to this mounting 38 also by means of a snap connection to the cylinder housing 14 be locked, as in the DE 201 16 818 U1 the applicant is described in detail, to which reference is hereby expressly made.

On the in 1 the right end has the cylinder housing 14 a flange section 44 with a radial groove on the outer circumference 46 that of attaching an elastomeric protective cap 48 serves. This in 3 right end of the bellows-shaped protective cap 48 is on a pressure pin 50 set that on the in 3 right side firmly with a push pin head 52 is connected, which is a connecting eye 54 for connection to a clutch pedal (not shown). This in 1 left end of the pressure pin 50 is with egg ball head 56 provided, over which the pressure pin 50 can be swiveled but is resistant to tension and compression with the plastic piston 12 connected is.

The one in a cylindrical blind hole 58 of the cylinder housing 14 pistons with longitudinal displacement 12 is by means of a slotted stop disc 60 in the cylinder housing 14 secured, which in turn by means of a locking ring 62 on a paragraph 64 of the cylinder housing 14 is attached. The stop disc 60 works with one on the pressure pin 50 provided train stop 66 as well as one on the pressure pin 50 attached pressure stop (not shown) together to increase the stroke of the piston 12 in the cylinder housing 14 to limit.

The piston 12 has two substantially cylindrical sections in the illustrated embodiment 68 . 70 that have a connecting section 72 are interconnected. Each of the cylindrical sections 68 . 70 is on the outer circumference with a radial groove 74 . 76 provided, of which the in 1 left radial groove 74 the inclusion of a primary sealing element 78 in the form of an elastomeric grooving, while in the 1 right radial groove 76 a secondary sealing element 80 - Also in the form of an elastomeric grooving - is included. In 1 are the sealing elements 78 respectively. 80 shown in the undeformed state to simplify the illustration. The primary sealing element 78 delimits one with the pressure connection in a manner known per se 24 communicating pressure room 82 in the cylinder housing 14 while a between the outer circumference of the piston 12 and the wall of the blind hole 58 provided trailing space 84 in a manner known per se from the primary sealing element 78 in 1 to the left and the secondary sealing element 80 in 1 is limited to the right.

The connecting section 72 of the piston 12 is finally adjacent to the cylindrical section 68 with a cross hole 86 provided, one through the cylindrical section 68 longitudinal bore extending therethrough 88 empties. On the in 1 left side of the longitudinal bore 88 a central suction valve known per se closes 90 on whose elastomeric valve body 92 by means of an end face of the piston on the pressure chamber side 12 attached, also made of plastic retaining cap 94 Movable in the axial direction on the piston 12 is held. The holding cap 94 also serves to secure the ring magnet without play 18 on the piston 12 as it is in the DE 202 08 568 U1 the applicant is described in detail on the hereby regarding the design and function of the retaining cap 94 and the central suction valve 90 explicit reference is made.

In the filled state of the master cylinder, which is mounted in the hydraulic clutch control 10 the pressure room communicates 82 in the in 1 shown basic position of the piston 12 via the pressure compensation hole 32 and the wake channel 30 with the overflow tank (not shown) as well as over the suction valve 90 who have favourited Longitudinal Hole 88 and the cross hole 86 with the trailing room 84 , The trailing room 84 itself is over the trailing hole 34 and the wake channel 30 connected to the hold tank. Now the piston 12 over that on the bolt head 52 Articulated clutch pedal (not shown) in the cylinder housing 14 into, ie, into 1 shifted to the left, the primary sealing element runs over 78 the pressure compensation hole 32 and thus interrupts the hydraulic connection between the pressure chamber 82 and the trailing tank. Through the in the pressure room 82 the valve body builds up pressure 92 of the suction valve 90 against the piston 12 pressed and thus prevents the hydraulic fluid from flowing out through the longitudinal bore 88 and the cross hole 86 in the trailing room 84 which is now over the trailing bore 34 and the pressure equalization hole 32 is connected to the hold tank. The one in the pressure room 82 setting pressure is via the pressure connection 24 and the liquid column between the master cylinder 10 and the one at the pressure connection 24 Transfer connected slave cylinder (not shown) to apply a disengagement force to the dry friction clutch (not shown) operatively connected to the slave cylinder. The axial movement of the piston 12 is by sensing the over the holding cap 94 on the piston 12 attached ring magnet 18 by means of the on the cylinder housing 14 fixed, the Hall sensor 20 and the associated flow guide 22 comprehensive sensor arrangement through the wall of the cylinder housing 14 detectable therethrough, as will be described in more detail below.

If the clutch is released, the restoring force of the clutch turns the liquid column into the master cylinder 10 moved back. Hurries, as can be caused, for example, by a return spring (not shown) on the clutch pedal, which is then on the pressure pin 50 pulled pistons 12 of the master cylinder 10 this backflow movement occurs in the pressure chamber 82 of the master cylinder 10 and a negative pressure in the line system to the slave cylinder. As a result of the pressure difference then between the two sides of the valve body 92 of the suction valve 90 prevails, the axially displaceable valve body lifts 92 from the piston 12 and opens the longitudinal hole 88 in the piston 12 , In the pressure room 82 Hydraulic fluid then flows from the trailing space 84 over the cross hole 86 and the longitudinal bore 88 in the piston 12 , Once the pressure difference between the two sides of the valve body 92 is balanced, the unnecessary amount of the hydraulic fluid that has flowed in through the now open again, ie from the primary sealing element 78 in 1 pressure equalization hole moved to the right 32 back into the expansion tank.

More details of the Hall sensor 20 and the associated flow guide 22 comprehensive sensor arrangement of the sensor device 16 are especially the 1 and 2 refer to. Accordingly, the sensor housing 38 a substantially L-shaped cross section, with a substantially cuboid base section 96 and stick to the basic section 96 subsequent connecting section 98 , The basic section 96 of the sensor housing 38 lies flat on the contact surface 36 of the cylinder housing 14 and serves to protect the Hall sensor 20 including the associated flow guide 22 , The opposite of the basic section 96 by means of a rib 99 supported connecting section 98 of the sensor housing 38 has a known plug socket 100 in which a plug (not shown) can be fastened by means of a snap connection in order to supply the sensor arrangement with current and to derive sensor signals from the sensor arrangement.

As the 1 and 2 further show, it is in the illustrated embodiment, the flux guide 22 around a flat sheet metal section, seen in plan view, made of a suitable magnetizable material, such as a ferromagnetic dynamo sheet section. The flow guide 22 lies with his in the 1 and 2 lower longitudinal surface 102 flat on a floor wall 104 of the basic section 96 of the sensor housing 38 and is attached to it in a suitable manner - in the illustrated embodiment by means of an adhesive connection (adhesive beads 106 in 2 ) - attached. Here, the arrangement is such that the flux guide 22 essentially in the direction of the axial relative movement of the piston 12 regarding the cylinder housing 14 extends or, in other words, essentially in the direction of the central axis of the blind bore 58 in the cylinder housing 14 and is parallel to it.

The Hall sensor 20 is due to the flow guide assigned to it 22 on. More specifically, the Hall sensor is located 20 in the embodiment shown here on the in 1 right longitudinal end of the flow guide 22 on the in the 1 and 2 upper longitudinal surface 108 of the flow guide 22 on, and just outside the area to be detected of axial relative positions of the ring magnet 18 to the Hall sensor 20 , It should be recalled here that the piston 12 in the in 1 shown basic position already in 1 has taken the rightmost position. The Hall sensor is useful 20 towards the flow guide 22 or aligned across it. Since the structure and function of Hall sensors are generally known and have already been described in the introduction to the description, insofar as this is necessary for an understanding of the present invention, further explanations are unnecessary here.

In the 1 and 2 is above the Hall sensor 20 an electrically connected to it, also in the sensor housing 38 integrated evaluation electronics 110 schematically indicated, which serves, on the one hand, the Hall sensor 20 to supply with power and the other from the Hall sensor 20 given, for the magnetic flux B in the flux guide 22 and thus the axial position of the piston 12 regarding the cylinder housing 14 prepare representative signals. On the evaluation electronics 110 are, after all, plug tabs 112 connected, which is in the connector 100 at the connection section 98 of the sensor housing 38 extend in to allow external power supply and external signal delivery.

In 4 is for those with reference to the 1 to 3 described sensor device 16 the course of the magnetic flux density B in the flux guide 22 in mT (milli-Tesla) over the path s of the piston 12 or the ring magnet attached to it 18 plotted in mm using the Hall sensor 20 can be detected if this is at a measuring point at 41.5 mm on the flux guide 22 is arranged. It can be seen that by means of the Hall sensor 20 detected magnetic flux density B steadily increases the closer the ring magnet 18 the Hall sensor 20 comes and the ring magnet keeps falling 18 from the Hall sensor 20 away. The characteristic of the magnetic flux density B does not have an exactly linear course over the path s. However, the course of the magnetic flux density B over the path s can easily be determined by means of the evaluation electronics 110 be linearized so that the sensor device 16 one of the way s of the piston 12 or the ring magnet attached to it 18 linearly dependent signal voltage U is able to deliver, as in 5 is shown. The 5 also illustrates the direction of magnetization of the ring magnet 18 , with the south pole S on one end face and the north pole N on the other end face of the ring magnet 18 ,

In 6 is finally for the referring to the 1 to 5 described sensor device 16 the magnetic field of the ring magnet 18 for a specific relative position of the ring magnet 18 to the Hall sensor 20 shown. It can be clearly seen that there is a quasi-bundling of the lower longitudinal surface 102 and the top longitudinal surface 108 into the flow guide 22 incoming field lines of the magnetic field of the ring magnet 18 in the flow guide 22 comes, so that there are relatively high field strengths H in the flux guide 22 result. The thus in the Flußleitelement 22 Concentrated magnetic flux can, as a result, be easily by means of the on the flux guide 22 arranged Hall sensor 20 be recorded.

Although in the above embodiment, the use of the sensor device 16 exemplary of a piston-cylinder arrangement with a "classic" piston 12 has been described, the two sealing elements cooperating with a housing-side tread 78 . 80 is for the subject man can be seen that the sensor device 16 can of course also be used in a so-called "stem piston", in which a housing-fixed (secondary) sealing element interacts with a running surface provided on the piston skirt, while a (primary) sealing element attached to the piston head interacts with a housing-side running surface. This could be the ring magnet 18 can also be attached to the piston head with a retaining cap.

The sensor device is also used 16 possible with a so-called "plunger" in which two or more sealing elements (not shown) fixed to the housing cooperate with a running surface (not shown) provided on the piston, as is shown, for example, in FIG DE 100 28 673 A1 the applicant is described. Here is on the cylinder housing according to the DE 100 28 673 A1 additionally a holder for the sensor housing 38 to be provided, for example as in the DE 201 16 818 U1 disclosed to the applicant. As for the "plunger" version, the fastening of the ring magnet 18 on the piston, can in turn refer to the DE 202 08 568 U1 the applicant (see there the 10 to 14 ), to which express reference is hereby made.

Although with reference to the 1 to 6 described embodiment of the evaluation electronics 110 than from the Hall sensor 20 separate part has been described, the evaluation electronics - as already mentioned at the beginning - can also be integrated in the Hall sensor. In this case, only a circuit board for attaching the Hall sensor and for power supply and signal derivation to / from the Hall sensor is required.

The 7 to 9 show further embodiments of the sensor device 16 which are to be described below only insofar as they differ from those with reference to the 1 to 6 described embodiment differ, the same or corresponding parts are provided with the same reference numerals. With regard to the operating principle, these exemplary embodiments do not differ from the exemplary embodiment according to FIGS 1 to 6 ,

According to 7 is the flow guide 22 in the longitudinal direction in two sections 114 . 116 divided between which the Hall sensor 20 is inserted. This is the hall sensor 20 directly in the in the flow guide 22 concentrated magnetic flux, which is the signal strength of the from the Hall sensor 20 emitted signal compared to the embodiment according to the 1 to 6 elevated. In one in 8th illustrated variant of this embodiment, the sections taper 114 . 116 of the flow guide 22 each to the Hall sensor 20 or are towards the Hall sensor 20 beveled.

In the embodiment according to 9 are two flow control elements 22 . 22 ' provided that run substantially parallel to each other and between which the Hall sensor 20 is inserted. That with this sensor arrangement from the Hall sensor 20 detected, for the magnetic flux density B and thus the relative position of the ring magnet 18 to the Hall sensor 20 representative signal has a curve plotted over the path s which is substantially more linear than that in 4 shown course, albeit the signal compared to a sensor arrangement with only one flux guide 22 has a lower signal strength.

In 9 Finally, a variant of the sensor arrangement is shown with dashed lines, in which two Hall sensors are used to obtain redundancy of the sensor signals 20 . 20 ' are provided, one of which is a Hall sensor 20 at a longitudinal end of the flow guide 22 is arranged while the other Hall sensor 20 ' at the other longitudinal end of the flow guide 22 is arranged. This variant of the sensor arrangement can also be used with only one flow guide element 22 be equipped.

Although in the embodiments described above, the flow guide 22 each made of the same material or, if necessary, in one piece from one material, a laminate made of possibly different materials can also be used as the flow guide element in accordance with the respective requirements.

It becomes a device for sensing the axial position of one of two movable relative to each other Components related of the other component, in particular a piston with respect to a cylinder housing Master or slave cylinders for a hydraulic clutch control for motor vehicles discloses which device is arranged on the one component magnetic signal element and at least one on the other component arranged magnetic flux sensitive Has sensor, by means of which the axial relative position of the signal element detectable to the sensor is. According to the invention Sensor at least one regarding of the sensor fixed flux guide assigned, which is at least on the other component Area to be detected from relative axial positions of the signal element extends to the sensor. The result is a simply constructed sensor device created by means of any axial with a small space requirement Relative positions between the components involved or their relative path detected can / can become.

10

Geberzylinder

12

Kolben

14

Zylindergehäuse

16

Sensorvorrichtung

18

Ringmagnet

20, 20'

Hallsensor

22, 22'

Flußleitelement

24

Druckanschluß

26

Befestigungsflansch

28

Nachlaufanschluß

30

Nachlaufkanal

32

Druckausgleichsbohrung

34

Nachlaufbohrung

36

Auflagefläche

38

Sensorgehäuse

40

Schraube

42

Befestigungsflansch

44

Flanschabschnitt

46

Radialnut

48

Schutzkappe

50

Druckbolzen

52

Druckbolzenkopf

54

Anschlußauge

56

Kugelkopf

58

Sackbohrung

60

Anschlagscheibe

62

Sicherungsring

64

Absatz

66

Zuganschlag

68

zylindrischer Abschnitt

70

zylindrischer Abschnitt

72

Verbindungsabschnitt

74

Radialnut

76

Radialnut

78

Primärdichtelement

80

Sekundärdichtelement

82

Druckraum

84

Nachlaufraum

86

Querbohrung

88

Längsbohrung

90

Nachsaugventil

92

Ventilkörper

94

Haltekappe

96

Grundabschnitt

98

Verbindungsabschnitt

99

Rippe

100

Steckerfassung

102

untere Längsfläche

104

Bodenwand

106

Klebstoffraupe

108

obere Längsfläche

110

Auswerteelektronik

112

Steckerzunge

114

Abschnitt

116

Abschnitt

LIST OF REFERENCE NUMBERS

10

Master cylinder

12

piston

14

cylinder housing

16

sensor device

18

ring magnet

20, 20 '

Hall sensor

22, 22 '

flux guide

24

pressure connection

26

mounting flange

28

running connection

30

running channel

32

Pressure compensating bore

34

replenishing bore

36

bearing surface

38

sensor housing

40

screw

42

mounting flange

44

flange

46

radial groove

48

protective cap

50

pushpin

52

Thrust bolt head

54

connecting eye

56

ball head

58

blind hole

60

stop disc

62

circlip

64

paragraph

66

cable stop

68

cylindrical section

70

cylindrical section

72

connecting portion

74

radial groove

76

radial groove

78

Primary sealing element

80

Secondary sealing element

82

pressure chamber

84

supply chamber

86

cross hole

88

longitudinal bore

90

cavitation valve

92

valve body

94

retaining cap

96

base portion

98

connecting portion

99

rib

100

plug socket

102

lower longitudinal surface

104

bottom wall

106

adhesive bead

108

upper longitudinal surface

110

evaluation

112

plug tongue

114

section

116

section

Claims (15)

Contraption ( 16 ) for sensing the axial position of one of two components that can be moved relative to one another with respect to the other component, in particular a piston ( 12 ) regarding a cylinder housing ( 14 ) of a master or slave cylinder ( 10 ) for a hydraulic clutch actuation for motor vehicles, with a magnetic signal element arranged on the one component ( 18 ) and at least one magnetic flux sensitive sensor arranged on the other component ( 20 . 20 ' ), by means of which the axial relative position of the signal element ( 18 ) to the sensor ( 20 . 20 ' ) can be detected, characterized in that the sensor ( 20 . 20 ' ) at least one regarding the sensor ( 20 . 20 ' ) fixed flow guide ( 22 . 22 ' ) is assigned, which is located on the other component at least over the area to be detected of axial relative positions of the signal element ( 18 ) to the sensor ( 20 . 20 ' ) extends. Contraption ( 16 ) according to claim 1, characterized in that the magnetic signal element is a permanent magnet, preferably a ring magnet ( 18 ) acts. Contraption ( 16 ) according to claim 1 or 2, characterized in that the magnetic flux sensitive sensor is a Hall sensor ( 20 . 20 ' ) acts. Contraption ( 16 ) according to one of the preceding claims, characterized in that the flow guide element ( 22 . 22 ' ) consists of a sheet metal section made of a suitable magnetizable material, such as a dynamo sheet section. Contraption ( 16 ) according to one of the preceding claims, characterized in that the flow guide element ( 22 . 22 ' ) extends essentially in the direction of the axial relative movement of one component with respect to the other component. Contraption ( 16 ) according to one of the preceding claims, characterized in that the magnetic flux sensitive sensor ( 20 . 20 ' ) on the assigned flow guide element ( 22 . 22 ' ) is present. Contraption ( 16 ) according to claim 6, characterized in that the magnetic flux sensitive sensor ( 20 . 20 ' ) on one of the longitudinal ends of the flow guide element ( 22 ) on a longitudinal surface ( 108 ) of the flow guide element ( 22 ) rests. Apparatus according to claim 6, characterized in that the magnetic flux sensitive Sensor on one end face of the flow guide is applied. Contraption ( 16 ) according to claim 6, thereby ge indicates that the flow guide element ( 22 ) in the longitudinal direction in two sections ( 114 . 116 ) is divided between which the magnetic flux sensitive sensor ( 20 ) is inserted. Contraption ( 16 ) according to claim 9, characterized in that the sections ( 114 . 116 ) of the flow guide element ( 22 ) each to the magnetic flux sensitive sensor ( 20 ) rejuvenate. Contraption ( 16 ) according to one of Claims 1 to 6, characterized in that two sensors sensitive to magnetic flux ( 20 . 20 ' ) are provided. Contraption ( 16 ) according to Claim 11, characterized in that the one sensor sensitive to magnetic flux ( 20 ) at one longitudinal end of the flow guide element ( 22 ) is arranged while the other sensor sensitive to magnetic flux ( 20 ' ) at the other longitudinal end of the flow guide element ( 22 ) is arranged. Contraption ( 16 ) according to one of claims 1 to 6, characterized in that two flow guide elements ( 22 . 22 ' ) are provided which run essentially parallel to each other and between which the magnetic flux sensitive sensor ( 20 . 20 ' ) is inserted. Contraption ( 16 ) according to one of the preceding claims, characterized in that the magnetic signal element ( 18 ) on a piston ( 12 ) of a master or slave cylinder ( 10 ) for a hydraulic clutch actuation for motor vehicles, while the magnetic flux sensitive sensor ( 20 ) with the associated flow guide ( 22 ) on a cylinder housing ( 14 ) of the master or slave cylinder ( 10 ) is attached. Contraption ( 16 ) according to claim 14, characterized in that the magnetic flux sensitive sensor ( 20 ) and the associated flow guide ( 22 ) in a sensor housing ( 38 ) are housed, which at a predetermined location on the cylinder housing ( 14 ) of the master or slave cylinder ( 10 ) is attached.