DE102018103241A1 - Actuator for actuating a friction clutch - Google Patents

Abstract

The invention relates to an actuator (1) for actuating a friction clutch, at least comprising a housing (2), a piston (4) movable in the housing (2) along an axial direction (3) and at least one between the housing (2) and the piston (4) a sealing surface (5) forming seal (6); wherein on the piston (4) a magnetic device (7) with at least one magnet (8) is fixed, wherein on the housing (2) a sensor (9) for measuring a magnetic field of the at least one magnet (8) is arranged, wherein the at least one magnet (8) is movable along a region (10) of a wall (11) of the housing (2), the region (10) constantly moving from the sealing surface (3) during operation of the actuator (1) in the axial direction (3). 5) is arranged at a distance.

Description

The present invention relates to an actuator, in particular an actuator for actuating a friction clutch, which serves to interrupt a flow of torque from a drive motor to a drive train of a motor vehicle.

To actuate friction clutches, such as single-disc dry clutches or double clutches, actuators are used for engagement and / or disengagement. An actuator may, for example, be a master cylinder or slave cylinder of an actuating device of the friction clutch. From the DE 10 2015 223 972 A1 For example, a master cylinder with a piston axially displaceably mounted in a housing known piston, wherein the piston builds upon actuation in a pressure chamber formed by the housing and piston pressure. The master cylinder has a sensor with a sensor arranged in the housing and a magnet attached to the piston for determining the position of the piston in the housing. The magnet is a neodynium-iron-boron, SmCo, AlNiCo or ferrite magnet, which is connected to the piston at a side of the piston pointing in the direction of the pressure chamber. The seals acting between the piston and the housing are arranged on the piston.

In the meantime, actuators are also known in which the seals can be arranged differently.

The object of the invention is at least partially to solve the problems described with reference to the prior art and in particular to provide an actuator for actuating a friction clutch, wherein a magnet in the smallest possible distance (along a radial direction) to one in the housing arranged sensor can be arranged.

This object is achieved with an actuator according to the features of the independent claim. Further advantageous embodiments of the invention are specified in the dependent formulated claims. It should be noted that the features listed individually in the dependent claims can be combined in a technologically meaningful manner and define further embodiments of the invention. In addition, the features specified in the claims are specified and explained in more detail in the description, wherein further preferred embodiments of the invention are shown.

The invention relates to an actuator for actuating a friction clutch, at least comprising a housing, a piston movable in the housing along an axial direction, and at least one seal forming a sealing surface between the housing and the piston. A magnet device with at least one magnet is attached to the piston, wherein a sensor for measuring a magnetic field of the at least one magnet is arranged on the housing. The at least one magnet is movable along a region of a wall of the housing, wherein the region is constantly spaced from the sealing surface in the axial direction during operation of the actuator.

The friction clutch is in particular a single-disc dry clutch or a double clutch. Such friction clutches are used to interrupt a torque flow from a drive motor to a drive train of a motor vehicle. The friction clutch can be engaged and / or disengaged by an actuator in order to activate and / or deactivate a torque flow from a drive motor to a drive train of the motor vehicle.

The actuator may in particular be a master cylinder connected to a clutch pedal, for example, or a slave cylinder. The slave cylinder can be connected directly to the friction clutch. The actuator has a housing, which is preferably at least partially made of plastic and / or metal. In the housing, a piston is arranged movable. In the case of a master cylinder can be constructed by means of the piston, a pressure in a pressure chamber for a hydraulic fluid through which a piston of a slave cylinder is movable via a hydraulic line. In the case of a slave cylinder, the piston may act directly or indirectly on the friction clutch to actuate the friction clutch.

The piston has a magnetic device, in particular releasably connected to the piston, for. B. via a plug connection is connected. The magnetic device or the piston in particular has a centering property relative to the housing, so that the magnetic device is as permanently as possible unchanged and coaxial with the piston in the housing along the axial direction movable.

The magnetic device comprises at least one first magnet and possibly also a second magnet, which may be, for example, neodynium-iron-boron magnets or SmCo, AlNiCo or ferrite magnets. The first magnet and possibly the second magnet are in particular part of a sensor device which serves to detect a position or a travel of the piston in the housing of the actuator.

The first magnet and the second magnet are in a moving direction (axial direction) of the Piston, spaced at a distance from each other. The distance is preferably 2 mm [millimeters] to 15 mm, preferably 3 mm to 7 mm. The first magnet and / or second magnet preferably have a length (in the axial direction of 5 mm to 10 mm, preferably 7 mm, a height (in a radial direction) of 5 mm to 10 mm, preferably 6 mm, and a width (in a circumferential direction) of 2 mm to 10 mm, preferably 7 mm.

To measure the magnetic field or the magnetic flux density of the magnetic field of the first magnet and possibly of the second magnet, in particular a Hall sensor is arranged as a sensor on the housing. Such a Hall sensor uses the so-called Hall effect for measuring magnetic fields. By a displacement of the first magnet and possibly the second magnet with the piston along the axial direction can be detected by the Hall sensor correlating therewith a change of the magnetic field in the region of the Hall sensor. This change causes a change in the Hall voltage.

In particular, the at least one (or each) magnet is arranged in a radial direction at a distance from the sensor.

The at least one magnet is in particular annular, cylindrical, cuboidal or ring segment-shaped.

In the present case, it is proposed that the at least one magnet is movable along a region of a wall of the housing, wherein the region is constantly spaced from the sealing surface in the axial direction during operation of the actuator. Ie. in particular, that the region (regardless of the position of the piston) does not contact a seal of the actuator or forms a sealing surface therewith.

In particular, only a single seal between the piston and the housing is provided.

In particular, the at least one (or the only) seal is disposed in the housing and the piston is movable relative to the seal along the axial direction.

Thus, the sealing surface between the piston and housing is formed in particular by a sealing lip of the seal and an outer circumferential surface of the piston.

This arrangement of the seal makes it possible for the at least one magnet to be arranged in a radial direction on the outside of the piston or on the circumferential surface of the piston forming the sealing surface. Thus, a distance between the magnet and the sensor can be further reduced.

In an assembly of the actuator, at least the magnetic device can already be arranged in the pressure chamber within the housing without contacting the at least one seal and thus widening and possibly damaging it.

The sealing element (the seal) has, in particular, an outer primary sealing lip on a side of the sealing element facing the pressure chamber. On a side facing away from the pressure chamber side of the sealing element, the sealing element has in particular an outer secondary sealing structure. The outer secondary seal structure may overhang the outer primary seal lip in a radially outward direction. According to the invention, a stop structure is provided on the sealing element between the outer primary sealing lip and the outer secondary sealing structure. The abutment structure is formed by one or more protrusions formed on the sealing element and intended to abut against the housing. The stop structure represents a defined stop for the sealing element when installed in the master cylinder and is used for Maßeinstellung. Furthermore, the stop structure also allows a division of the contact pressures of the sealing element against the housing. In this case, this division can be influenced by the number and shape of the projections. As material for the sealing element all conventional elastomers come into question.

In one embodiment, the sealing element (seal) has an inner primary sealing lip facing the pressure space and adjacent to the piston. The inner primary sealing lip and the outer primary sealing lip are mainly used to seal a supply for hydraulic fluid (pressure medium), can be compensated for the losses of hydraulic fluid against the pressure chamber or close when in the pressure chamber, an overpressure is built up, ie if Piston is introduced into the pressure chamber. For this purpose, the piston presses the inner primary sealing lip radially outward upon introduction into the pressure chamber, and as a result of the resulting elastic deformation of the sealing element, the outer primary sealing lip is pressed against the housing and thus closes the provided in the region of the sealing element supply for hydraulic fluid. This cooperation of the piston with the sealing element is particularly supported in one embodiment in that the piston has a chamfer on the side facing the pressure chamber, more precisely in the region which is to come into contact with the inner primary sealing lip. By the movement of the piston in the direction of the pressure chamber, preferably a piston with a chamfer as just mentioned, so the inner and the outer primary sealing lip can be prestressed in the manner just described, resulting in a closure of the supply of hydraulic fluid. The inner primary sealing lip is pressed against the piston, in a piston with bevel against the chamfer, thereby sealing in the region of the piston or the chamfer from the pressure chamber.

It is also advantageous if the piston in the front region receives a structure which allows a fluid exchange in the end stop. For example, one or more grooves may be formed on an end face of the piston. In one embodiment, the sealing element on the side facing away from the pressure chamber side of the sealing element has an inner secondary sealing structure which is adjacent to the piston. The inner secondary sealing structure, like the outer secondary sealing structure, serves to permanently seal portions of the master cylinder against the pressure space. On the other hand, it is the primary task of the primary sealing lips to release or close the supply of hydraulic fluid as a function of the piston position. Inner and outer secondary sealing structure may be formed, for example, in O-ring geometry. In one embodiment of the master cylinder, at least one recess is provided on a side of the sealing element facing the housing. The at least one recess ensures a better venting, in particular despite manufacturing tolerances. Likewise, the at least one recess ensures improved flow of the hydraulic fluid to be fed into the pressure chamber. In one embodiment, at least one radial bore is introduced into the sealing element. The bore extends from a location between the outer primary seal lip and the outer secondary seal structure to a location between the inner primary seal lip and the inner secondary seal structure.

Such a seal (referred to there as a sealing element) and their arrangement in an actuator is from the post-published DE 10 2017 113 623 A1 known.

Another such seal (referred to therein as a sealing element) and their arrangement in an actuator is from the post-published DE 10 2017 119 644 A1 known.

Preferably, the magnetic device is releasably connected to the piston, for. B. via a clip connection (eg., Ball / dome, possibly with slotted dome), a screw, via a press fit.

Alternatively or additionally, the magnetic device may also be permanently connected to the piston, z. B. via an adhesive bond, welded joint, etc.

In particular, the magnetic device is connected without play to the piston. The play-free connection enables the most accurate possible evaluation of the magnetic field detected by the sensor.

According to a preferred embodiment, the magnet device is secured during a displacement along the axial direction by a guide device against rotation in a circumferential direction relative to the housing.

In particular, the guide device is formed by at least one elevation pointing inward in a radial direction or in the radial direction pointing outward (for example a groove) of the wall.

According to a particularly preferred embodiment, at least one of the magnetic device and the at least one magnet is arranged in a radial direction further outward than the piston. In particular, so the distance between the magnet and the sensor can be reduced.

The at least one magnet may consist of a magnetizable plastic. In particular, the magnet is designed as an injection molded part.

Preferably, the magnetic device and the at least one magnet are made in one piece, in particular as an injection molded part.

It is further proposed an actuator for a friction clutch, comprising at least the actuator already described and at least one of the group master cylinder and slave cylinder, wherein the actuator is connected via pressure lines for exchanging a pressure medium and for actuating the friction clutch with the master cylinder or slave cylinder.

In particular, the actuating device comprises at least one master cylinder or a slave cylinder, which is designed as an actuator.

The comments on the actuator apply equally to the actuator and vice versa.

By way of precaution, it should be noted that the numerical terms used here ("first", "second",...) Primarily (only) serve to distinguish a plurality of similar objects, variables or processes, ie in particular no dependence and / or order of these objects, quantities or mandate processes to one another. Should a dependency and / or order be required, then this is explicitly stated here or it obviously results for the person skilled in the art when studying the concretely described embodiment.

• 1 zeigt einen Aktuator 1 im Längsschnitt in einer perspektivischen Ansicht.

The invention and the technical environment will be explained in more detail with reference to the figure. It should be noted that the invention should not be limited by the embodiment shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figure and to combine them with other components and findings from the present description. In particular, it should be noted that the figure and in particular the illustrated proportions are only schematic.

• 1 shows an actuator 1 in longitudinal section in a perspective view.

The actuating device 16 here is a master cylinder 17 that as an actuator 1 is executed and via a pressure line 19 with a slave cylinder 18 is connected to actuate a friction clutch. The actuator 1 has a housing 2 and one in the housing 2 movable piston 4 on and exactly one between the housing 2 and the piston 4 a sealing surface 5 training seal 6 , The piston 4 is in the case 2 along an axial direction 3 movable. On the piston 4 is a magnetic device 7 arranged, wherein the magnetic device 7 two magnets 8th which is in the axial direction 3 are arranged at a distance from each other. On the case 2 is a (Hall) sensor 9 for measuring the magnetic field of the magnets 8th arranged, being between the sensor 9 and the two magnets 8th in the radial direction 14 an air gap is formed. The magnets 8th are in the radial direction 14 at a distance 21 from the sensor 9 arranged.

The magnet 8th are along an area 10 a wall 11 of the housing 2 movable, the area being 10 during operation of the actuator 1 in the axial direction 3 constantly from the sealing surface 5 spaced apart. The area 10 thus contacted regardless of the position of the piston 4 no seal 6 of the actuator 1 or forms with this no sealing surface 5 ,

The only seal 6 is in the case 2 arranged and the piston 4 is opposite the seal 6 along the axial direction 3 movable. This will be the sealing surface 5 between pistons 4 and housing 2 through a sealing lip of the seal 6 and an outer peripheral surface of the piston 4 educated.

This arrangement of the seal 6 allows the magnets 8th in a radial direction 14 outside of the piston 4 or from the sealing surface 5 forming peripheral surface of the piston 4 can be arranged. This can be a distance 21 between magnets 8th and sensor 9 in the radial direction 14 be further reduced.

When mounting the actuator 1 can the magnetic device 7 So already in the pressure chamber and thus beyond the seal 6 inside the case 2 be arranged without the seal 6 through the magnet device or the magnets 8th will be contacted.

The magnetic device 7 is with the piston 4 via a clip connection, here ball (on the piston) and dome (on the magnetic device 7 ) detachably connected.

The magnetic device 7 is during a displacement along the axial direction 3 by a guide device 12 against rotation in a circumferential direction 13 opposite the housing 2 secured. The management device 12 is through, in a radial direction 14 outward facing depression 14 (a groove) of the wall 11 formed, in which are the magnets 8th and the magnetic device 7 extend. Opposite the circumferential direction 13 form magnetic device 7 and deepening 15 Stops off, so that a rotation of the magnetic device relative to the housing 2 not possible.

Recognizable are the magnetic device 7 and the magnets 8th in the radial direction 14 farther out than the piston 4 arranged. This can be the distance 21 between magnets 8th and sensor 9 be reduced.

LIST OF REFERENCE NUMBERS

1

actuator

2

casing

3

axial direction

4

piston

5

sealing surface

6

poetry

7

magnetic device

8th

magnet

9

sensor

10

Area

11

wall

12

guide means

13

circumferentially

14

radial direction

15

deepening

16

actuator

17

Master cylinder

18

slave cylinder

19

pressure line

20

print media

21

distance

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102015223972 A1 [0002]
• DE 102017113623 A1 [0024]
• DE 102017119644 A1 [0025]

Claims (10)

Actuator (1) for actuating a friction clutch, at least comprising a housing (2), a piston (4) which can move in the housing (2) along an axial direction (3) and at least one between the housing (2) and the piston (4 ) a sealing surface (5) forming seal (6); wherein on the piston (4) a magnetic device (7) with at least one magnet (8) is fixed, wherein on the housing (2) a sensor (9) for measuring a magnetic field of the at least one magnet (8) is arranged, wherein the at least one magnet (8) is movable along a region (10) of a wall (11) of the housing (2), the region (10) constantly moving from the sealing surface (3) during operation of the actuator (1) in the axial direction (3). 5) is arranged at a distance. Actuator (1) to Claim 1 in that the seal (6) is arranged in the housing (2) and the piston (4) is movable relative to the seal (6) along the axial direction (3). Actuator (1) according to one of the preceding claims, wherein the magnetic device (7) is releasably connected to the piston (4). Actuator (1) according to one of the preceding claims, wherein the magnetic device (7) is connected without play to the piston (4). Actuator (1) according to one of the preceding claims, wherein the magnetic device (7) during a displacement along the axial direction (3) by a guide device (12) against rotation in a circumferential direction (13) relative to the housing (2) is secured. Actuator (1) to Claim 5 wherein the guide means (12) by at least one, in a radial direction (14) inwardly facing elevation or in the radial direction (14) outwardly facing recess (15) of the wall (11) is formed. Actuator (1) according to one of the preceding claims, wherein at least one of the magnetic means (7) and the at least one magnet (8) in a radial direction (14) is arranged further outwardly than the piston (4). Actuator (1) according to one of the preceding claims, wherein the at least one magnet (8) consists of a magnetizable plastic. Actuator (1) to Claim 8 , wherein the magnetic device (7) and the at least one magnet (8) are made in one piece. Actuating device (16) for a friction clutch, comprising at least one actuator (1) according to one of Claims 1 to 9 and at least one of the group of master cylinder (17) and slave cylinder (18), wherein the actuator (1) via pressure lines (19) for exchanging a pressure medium (20) and for actuating the friction clutch with the master cylinder (17) or slave cylinder (18). connected is.

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