DE102017111086A1 - Hydraulic cylinder with magnetic position measurement, in particular clutch slave cylinder - Google Patents

Abstract

The invention relates to a hydraulic cylinder (1) having a cylinder chamber (21), a cylinder housing (2) and a piston (3) which is at least partially disposed in the cylinder chamber (21) during operation, wherein with the cylinder housing (2) Magnetic field sensitive sensor (63) is connected, characterized in that at least one magnet (6, 61, 62) on or in the piston (3) is arranged, wherein in use by the sensor (63) for determining a position of the piston (3 ) in the cylinder chamber (21) a magnetic field from the magnet (6, 61, 62) can be detected. The invention also relates to a measuring method for detecting a position of a piston (3) in a hydraulic cylinder (1).

Description

This invention relates to a hydraulic cylinder, which is preferably designed as a clutch slave cylinder. The hydraulic cylinder comprises a cylinder chamber, a cylinder housing and a piston. Connected to the cylinder housing is a magnetic field sensitive sensor for measuring the position of the piston in the cylinder. Furthermore, the invention relates to a measuring method for detecting the position of a piston in a clutch slave cylinder.

In order to detect the exact position of the clutch, it is state of the art to attach a measuring system to the hydraulic cylinder. For example, according to the patent EP 1 898 111 B1 a magnet in a guide shoe on the outer diameter of the clutch slave cylinder with radial play, but be guided axially backlash. This ensures a consistent radial distance from the magnet to the sensor. This solution provides a sensor attachment on the outer circumference of the clutch slave cylinder.

In another solution according to the prior art according to the DE 102 42 841 B4 For example, a collar includes a support arm which carries the magnet at its outer radial end. By axial pressure of the release spring, the magnet is guided axially free of play. The sensor is mounted on the outer diameter of the clutch slave cylinder in this approach.

In another state-of-the-art solution from the coupling specialist LuK GmbH & Co. KG, Bühl, a lever is attached to the clutch slave cylinder. On this lever, a magnet holder is mounted, which guides the magnet in a circular path around the sensor. The entire construction is mounted outside the actual cylinder housing.

A disadvantage of the prior art is that hydraulic cylinders, in particular clutch slave cylinder, with measuring function for the piston position according to the prior art due to the cantilevered measuring mechanism are made less compact. In addition, positional errors occur due to wobble that can be induced by the release bearing.

The object is therefore to provide a compact hydraulic cylinder, which includes a measuring function for the position of the piston.

This object is solved by the features of the independent claims. Further advantageous developments are the subject of the dependent claims.

The invention relates to a hydraulic cylinder, wherein at least one magnet is arranged on or in the piston, wherein in operation of the sensor, a magnetic field can be detected by the magnet.

A piston is understood to mean an element which can dip into and out of a cylinder chamber. As a piston is not a portion or element that is connected to the actual piston and protrudes substantially from this.

In such an embodiment of a hydraulic cylinder, the guidance of the piston in the cylinder can be used to guide a magnet with respect to a sensor. There may be as good guidance between the magnet and the sensor as between the piston and the hydraulic cylinder. The magnet is arranged by its arrangement on or in the piston near at least one guide surface. This results in no long lever that generates relative movements between the magnet and sensor relative movements between the piston and the cylinder chamber at a distance from the piston larger relative movements. The magnet is preferably located within a guide surface surrounding the piston on the outside or within its alignment.

Preferably, the magnet is disposed in or on a portion of the piston which is guided on a guide surface. This section is not connected to the guide surface via flexible sections. The portion is also preferably not connected with clearance with a guide abutment surface of the piston, which is guided on the guide surface. The section is preferably arranged near a guide surface. Preferably, the portion comprises a guide opposing surface of the piston. A greater distance from the guide surface causes, for example, wobbling motions of the piston to appear magnified by leverage as relative movement between the magnet and the sensor. This causes measurement errors, because in fact the axial relative position between magnetic field and sensor can shift. Due to a cross-sensitivity of the sensor, an error can also result from changes in the radial relative position between the magnetic field and the sensor. Both take place with wobbling movements of the piston.

By a sensor is meant a sensitive element which may be arranged in a sensor system for the acquisition of measured values. In particular, a sensor is a Hall sensor.

A magnet is preferably designed as a block. Preferably, it is positively in the Piston used. He can also be glued. It is also possible to integrate the magnet as a castable, in particular injection-moldable magnetizable material by casting, in particular injection molding, in a likewise injection-molded piston or a prefabricated metallic piston. After casting, the magnetic material can be magnetized. The magnet can thus be a cohesively integrated into the piston magnet.

Preferably, the guide surface is at the same time a sealing counter surface for a seal of the piston for sealing the cylinder chamber. In this way, the guide surface can be used simultaneously for sealing effect.

Preferably, the magnet is disposed at a location on the piston that is in at least one position of the piston within the cylinder chamber.

As a cylinder chamber also applies a non-pressure medium-filled portion of the cylinder chamber, which may however be filled in another position of the piston with pressure medium. Advantageously, can be achieved by such an arrangement that the magnet can be located far in the direction of the bottom of the cylinder chamber.

Preferably, a magnet is disposed at a location on the piston that is on a non-pressurized side of a seal on the piston,
and / or a magnet is disposed at a location on the piston located on a pressurizable side of the seal on the piston.

In other words, a seal of at least one magnet can be arranged in the direction of a pressurized part of the cylinder chamber and / or a seal can be arranged from at least one magnet in the direction of a non-pressurized part of the cylinder chamber.

In the former option, there is the advantage of being able to position a magnet further in the extension direction of the piston. In the second-mentioned option, there is the advantage of arranging a magnet far in the retraction direction. In particular, in the second option mentioned, the magnet can be arranged in the fully retracted state of the piston near the bottom of the cylinder chamber. This makes it possible to place the sensor further in the direction of the bottom of the cylinder chamber than if all the magnets were arranged on the non-pressurized side of the piston. If the first and the second option are realized, an almost arbitrary distance of the magnets from each other can be realized, while maintaining the advantage of the first option. One or more seals may be disposed between two magnets.

Preferably, two separate seals are arranged on the piston, wherein in particular the seals and / or their sealing points are positioned differently in the axial direction of the piston.

For example, a region lubricated by the pressure medium on the inner surface and on the outer surface of the piston may vary widely in the axial direction. In addition, other elements, such as a magnet, can be placed between the seals. It is also possible to realize a mechanically fixed path past the seals, without having to traverse a seal.

Preferably, the sensor is arranged outside the cylinder chamber and connected to a cylinder housing, wherein a pressure wall of the cylinder housing is adapted to be penetrated by the magnetic field of the magnet in at least one position of the piston, such that the magnetic field from the sensor for measuring the position of the piston is receivable.

When the sensor is located outside the cylinder chamber and the magnetic field is applied through the pressure chamber wall of the cylinder chamber, the signal from the sensor need not be transmitted outward from the cylinder chamber. By connecting the sensor to the cylinder housing, it is meant that the sensor or its sensor housing can be fastened directly to the cylinder housing. Alternatively, it may be mechanically connected to the cylinder housing via one or more intermediate elements or intermediate sections.

Preferably, the piston is designed as an annular piston. An annular piston has an inner and an outer mating surface and an inner and an outer seal. Advantageously, a hydraulic cylinder designed as a clutch slave cylinder can be arranged around a transmission shaft.

In particular, exactly two magnets are arranged on or in the piston at a distance in the axial direction to each other.

Such an arrangement of the magnets allows the formation of a magnetic field between the two magnets, which extends further than would a single magnet do. In this way, the measuring path of the position detecting device can be extended without the need for larger magnets. The position of the piston relative to the cylinder housing becomes preferably determined by the strength and / or direction of the magnetic field measured by the sensor.

Preferably, the piston comprises at least two components, which are separable from one another in the axial direction of the piston, wherein a seal is preferably arranged between the components of the piston in the mounted state.

The subdivision of the piston into two components has the advantage that a seal can be introduced between the components. This can be positively fixed between the two components of the piston. In this way, it is possible to easily change this seal.

Preferably, a portion of the piston, which is arranged further in the direction of a bottom of a cylinder chamber, formed as a holding device for a magnet, wherein the holding device is preferably designed as a retaining ring. In particular, it can also serve as a fastening ring for a seal. In this way, a magnet can be arranged on the pressure side of a seal.

In other words, the invention can be described as follows. A clutch slave cylinder normally includes the components bearing, piston, seal, cylinder housing, release spring and dirt protection ring. When installing a Hall sensor, which is used to measure the position of the piston, between the pressure wall and the release spring of a Kupplungsnehmerzylinders problems may arise in the arrangement of the magnets required for the distance measurement.

By mounting the magnet on the movable piston, the distance measurement can be done directly on a pressure wall of the clutch slave cylinder. This installation location reduces the measurement inaccuracies, since the tumbling motion of the bearing no longer plays a role and play between pistons and guide surfaces of the cylinder chamber less impact. The sensor or its sensor housing can be arranged directly on the pressure wall of the clutch slave cylinder.

In order to improve the position of the magnetic field, which depends on the positions of the magnets on or in the piston relative to the sensor, two individual seals may be provided on the piston, as opposed to mounting a magnet on a conventional piston with a central seal each of which seals one of the annular surfaces of an annular cylinder.

To make the magnetic field stronger and more clearly measurable, two block magnets can be used. These two block magnets preferably have a defined distance from each other. The sensor can be placed as far away from a ferromagnetic release bearing, in particular outside of the pressure wall of the cylinder chamber.

Preferably, a position in the middle between the two magnets with respect to the axial direction in the maximally extended position of the piston on the largest possible distance to the sensitive element. Preferably, the sensor is arranged as far away from the release bearing due to the space required and the influence of the ferromagnetic release bearing on the measurement. To realize this, the position of the magnet on the piston can be adjusted. In the design with a magnet outside the cylinder chamber, the magnet can not be arranged further in the direction of the bottom of the cylinder chamber, since the lower magnet can be applied to the seal at maximum. In order nevertheless to be able to place the magnets according to the requirements, instead of a central seal on the side in the direction of the bottom of the cylinder chamber in a variant of the invention, two seals may be provided on the piston. These may be a seal on the outside and a seal on the inside of the piston.

The piston may be designed in two parts to be able to attach the two-part seal without cohesive fastening between the components of the piston can.

In order to prevent rotation of the components of the piston to each other, a Montageverdrehsicherung is preferably provided. The Montageverdrehsicherung on a component of the piston is designed so that it fits in exactly one rotational position on its counterpart to the other component of the piston. This prevents incorrect assembly and thus misalignment of the magnets to each other.

Preferably, at least one Betriebsverdrehsicherung between the piston and the cylinder housing is provided, in particular at the end of the piston, which is directed away from the bottom of the cylinder chamber. The anti-rotation lock prevents the piston from rotating to the cylinder housing and thus also to the sensor. Here is the Betriebsverdrehsicherung preferably also designed to prevent incorrect installation so that it fits only in a rotational position in the counterpart (Poka Yoke).

At a Betriebverdrehsicherung one or more snap hooks may be provided. These can prevent that from happening Release bearing releases during transport or assembly of the clutch slave cylinder from the clutch slave cylinder.

Another variant provides a seal, which is arranged between the piston and a holding device. From the holding device, the magnet, which is further arranged in the direction of the bottom of the cylinder chamber, are held. In particular, the magnet is fixed by a magnet holder. This holding device, which is preferably designed as a retaining ring, can be anchored with a plurality of press-fit pins in the seal. For receiving the press-fit pins, the fastening device has one hole each. The material of the seal is preferably incompressible, so that the pins are securely fixed in position after assembly. As a material for all seals EPDM is preferably used.

Another variant provides an expansion seal for sealing the piston. A spreading seal is a seal with a recess in the direction of the pressure side, which spreads the seal when pressure is applied and presses against its counter surface.

The expansion seal is preferably arranged between two components of the piston, wherein the component is preferably formed in the direction of the bottom of the cylinder chamber as a retaining ring. Preferably, recesses are provided in the retaining ring, through which the fluid can flow. The fluid forces the seal to seal axially against the piston and radially against the cylinder housing.

In particular, a magnet can be mounted in a holding device. The retaining ring can also serve as a fastening ring for a seal.

By means of injection pins which pass through the seal, a retaining ring can be attached to the piston. The seal has continuous recesses. The seal has sealing points on both surfaces of the annular cylinder chamber. The construction is preferably designed so that the seal is biased in the assembled state between the piston and the retaining ring, so that it seals both against the retaining ring, as well as against the piston.

The invention can be realized in a hydraulic cylinder, whose inner ring is connected to the piston, as well as in a hydraulic cylinder whose piston is connected to the outer ring. The connection between the piston and the bearing ring is preferably free of play in the axial direction of the piston.

In a further aspect of the invention, a measuring method for detecting the position of a piston in a cylinder chamber of a hydraulic cylinder, in particular a clutch slave cylinder, proposed in which for measuring a position of a piston of a hydraulic cylinder, a magnet is arranged on or in the piston and the measurement means a magnetic field, in particular by a pressure wall of the hydraulic cylinder, takes place.

• 1 eine Schnittansicht auf einen Hydraulikzylinder nach dem Stand der Technik;
• 2 eine Schnittansicht eines Hydraulikzylinders gemäß der Erfindung in einer ersten Ausführungsform, wobei die linke Hälfte des dargestellten Hydraulikzylinders den Hydraulikzylinder ausgefahrenen Zustand zeigt, während die rechte Hälfte den Hydraulikzylinder im eingefahrenen Zustand zeigt,
• 3 eine Schnittansicht eines Hydraulikzylinders gemäß der Erfindung in einer zweiten Ausführungsform, wobei die linke Hälfte des dargestellten Hydraulikzylinders den Hydraulikzylinder ausgefahrenen Zustand zeigt, während die rechte Hälfte den Hydraulikzylinder im eingefahrenen Zustand zeigt,
• 4 eine perspektivische Darstellung eines Kolbens des Hydraulikzylinders in der zweiten Ausführungsform;
• 5 einen Schnitt durch einen Kolben des Hydraulikzylinders in der zweiten Ausführungsform;
• 6 einen Schnitt durch einen Kolben des Hydraulikzylinders in einer dritten Ausführungsform;
• 7 einen Schnitt durch einen Kolben des Hydraulikzylinders in einer vierten Ausführungsform und
• 8 einen Schnitt durch einen Befestigungsstift aus 7.

The invention will be explained in more detail by means of embodiments in conjunction with accompanying drawings. Here are shown schematically:

• 1 a sectional view of a hydraulic cylinder according to the prior art;
• 2 5 is a sectional view of a hydraulic cylinder according to the invention in a first embodiment, wherein the left half of the illustrated hydraulic cylinder shows the hydraulic cylinder extended state, while the right half shows the hydraulic cylinder in the retracted state,
• 3 a sectional view of a hydraulic cylinder according to the invention in a second embodiment, wherein the left half of the illustrated hydraulic cylinder shows the hydraulic cylinder extended state, while the right half shows the hydraulic cylinder in the retracted state,
• 4 a perspective view of a piston of the hydraulic cylinder in the second embodiment;
• 5 a section through a piston of the hydraulic cylinder in the second embodiment;
• 6 a section through a piston of the hydraulic cylinder in a third embodiment;
• 7 a section through a piston of the hydraulic cylinder in a fourth embodiment and
• 8th a section through a fixing pin 7 ,

1 shows a section through a hydraulic cylinder 1 , which is a cylinder housing 2 , a piston 3 , a dirt protection ring 4 , an inner ring 10 , Rolling elements 9 and an outer ring 8th includes.

The cylinder housing 2 includes a central tube 24 through which, for example, a transmission shaft can be plugged. The piston 3 is annular and shown in the extended state.

A part of the piston 3 is in an annular cylinder chamber 21 arranged. The piston 3 is opposite the cylinder chamber 21 with a seal 31 sealed. On the cylinder housing 2 is a support arm 22 arranged on which a sensor carrier 23 is arranged with a sensor not explicitly shown.

The sensor is in operative connection with a magnet 6 standing in a magnet holder 43 is arranged. The magnet holder 43 is on a magnet carrier 42 Arranged with the dirt protection ring 4 mechanically connected. When the piston 3 in the cylinder chamber 21 moves, moves with the piston of the inner ring 10 , the dirt protection ring 4 , the magnet carrier 42 and the magnet holder 43 with the magnet 6 , The magnet 6 strokes along a surface of the sensor carrier facing it and generates a measuring signal in the sensor according to its position.

A disadvantage of this arrangement is that the magnetic carrier 42 and the magnet holder 43 cause the magnet to be far from the guide between the piston 3 at the cylinder chamber 21 is removed and thus relative movements between the piston 3 and the cylinder housing 2 translated as a relative movement between the magnet with a big lever 6 and the sensor carrier 23 appear there and cause significant measurement errors.

2 shows a cross section through a hydraulic cylinder 1 , which is designed as a clutch slave cylinder, in a first embodiment.

In the 2 is the hydraulic cylinder 1 shown in half-section on the left side of the center line in the maximally extended state, while it is shown in half section on the right side of the center line in the maximum retracted state.

The hydraulic cylinder 1 includes a cylinder housing 2 with an annular cylinder chamber 21 in which, in the extended state, a small part of an annular piston 3 and retracted state a large part of the piston 3 located.

The piston 3 has two recesses, each containing a magnet 61 respectively. 62 is arranged. The piston 3 acts on an inner ring 10 a release bearing, which the piston force via rolling elements 9 on an outer ring 8th transfers.

On the inner ring 10 there is a dirt protection ring 4 on, which by a release spring 7 against the inner ring 10 is pressed. On the outside of a pressure wall 65 in the area of the cylinder chamber 21 the outer circumference of the cylinder housing 2 is a sensor 63 arranged.

The sensor 63 is inside a sensor housing 65 arranged. The sensor 63 is sensitive to magnetic fields and reacts to magnetic fields of the magnets 61 and 62 , In the maximum extended state of the piston 3 reaches the sensor 63 a weak magnetic field of the magnet 62 from which it can be seen that the piston 3 maximum is extended.

In the maximum retracted state reaches the sensor 63 a field of magnet 61 and depending on the direction of magnetization of the magnets 61 and 62 also the effect of the magnet 62 , This results in a characteristic course of the measured magnetic field along the path of the piston 3 from the maximum extended position to the maximum retracted position, on the basis of which a detection of the position of the piston with respect to the cylinder housing 2 is possible.

A disadvantage of the first embodiment is that the magnetic field of the magnet 62 that the sensor 63 in the maximum extended position of the piston 3 achieved, is relatively weak and therefore can only be detected with reduced accuracy.

In the first embodiment, the piston 3 with an annular seal 31 opposite the cylinder chamber 21 sealed.

The seal 31 has two sealing lips, one of which with the outer guide surface 66 and one with the inner guide surface 67 is in sealing contact. The seal 31 is form-fitting with one end of the piston 3 connected in the direction of the ground 211 the cylinder chamber 21 is directed.

3 shows a second embodiment of a hydraulic cylinder 1 in a cut.

Like in the 2 is the hydraulic cylinder 1 shown in half-section on the left side of the center line in the maximally extended state, while one on the right side of the center line in the maximum retracted state is shown in half section.

3 agrees in many details with the 2 about one. Identical features are designated by the same reference numerals and will not be described separately again. It's up 2 directed.

Unlike the 2 The first embodiment shown is the annular piston 3 in the second embodiment in two components 32 and 33 divided. Near the end of the component 32 of the piston leading to the bottom surface 211 the cylinder chamber 21 is directed, there is a magnet 62 ,

In the extension direction closes to the magnet 62 a sealing ring 312 with sealing effect to the outside. He acts with the guide surface 66 together. To the component 32 of the piston 3 closes off the sealing ring 312 seen in the direction of extension, the component 33 of the piston 3 at. The component 32 and the component 33 overlap each other in the radial direction at their ends facing each other. It has the overlapping portion of the component 32 a larger diameter than the overlapping portion of the component 32 ,

At approximately the same position as the overlap between the component 32 and the component 33 is a sealing ring 311 arranged with sealing effect inside. From the overlap is further in the extension of the magnet 61 arranged.

The sealing ring 311 and the magnet 61 are at the end of the component 33 of the piston, the ground 211 the cylinder chamber 21 is facing. Incidentally, the hydraulic cylinder corresponds 1 the second embodiment of the first embodiment.

More details about the two-piece piston 3 the second embodiment are in the 4 and 5 shown.

4 shows the two-piece piston 3 the second embodiment of the hydraulic cylinder in a perspective view.

In the embodiment shown it is clear that the magnets 61 and 62 not over the entire circumference of the piston 3 but only over a small section of it.

The magnet 61 is in a magnet holder 332 the component 33 arranged the piston. The magnet 62 is in a magnet holder 322 the component 32 arranged the piston.

A magnet holder 322 . 332 can be considered deepening in the particular component 32 . 33 of the piston 3 be designed.

So that the magnets 61 and 62 both reproducible with the in 4 not shown interact sensor, are anti-rotation between the components 32 and 33 of the piston 3 as well as between the component 33 of the piston and the cylinder housing 2 , this in 4 not shown, provided.

At the component 32 of the piston 3 is an anti-rotation tab 321 provided, which form-fitting with a Verdrehsicherungsaussparung 331 the component 33 of the piston 3 can interact. Such is an alignment of the magnets 61 and 62 in the extension direction.

To prevent rotation of the piston relative to the cylinder housing carries the component 33 the piston at its end, the bottom 211 the cylinder chamber 21 turned away, several anti-rotation devices 334 that is radial towards the interior of the piston 3 protrude. You can positively cooperate with grooves in the cylinder housing, whereby a rotation is effected. Next are at the end, which is the floor 211 the cylinder chamber 21 turned away, snap hooks 333 provided by means of which in 4 not shown release bearing on the piston 3 can be clipped on.

5 shows a cross section through the in 4 shown piston.

Identical features are designated by the same reference numerals and will not be explained separately again.

In the 5 is in addition to recognize that the component 32 a sealing ring 311 acting inwards on her to the ground 211 the cylinder chamber 21 bearing directed end.

The sealing ring 311 is preferred between the component 32 and the component 33 of the piston pinched. An overlap area 34 can be designed so that in this a ring land 3432 the component 32 of the piston 3 and a ring pier 3433 the component 33 of the piston are in positive engagement with each other.

For connecting the ring bridges 3432 and 3433 can ratchet teeth on the inner circumference of the larger of the ring lands 3433 and / or on the outer circumference of the smaller of the ring lands 3432 be provided. The piston can be mounted by the ring lands 3432 and 3433 be pushed over each other.

6 shows a piston 3 a third embodiment of the hydraulic cylinder. The piston 3 is two-part with a component 32 and a retaining ring 34 executed.

The retaining ring 34 is at the end of the component 32 of the piston 3 arranged that to the ground 211 the cylinder chamber 21 is directed. Between the retaining ring 34 and the component 32 is an annular seal 31 arranged.

The seal 31 acts in the direction of the interior and in the direction of the exterior of the piston, including a sealing lip 314 . 315 at the seal 31 is arranged.

The retaining ring comprises a magnet holder 343 , The magnet holder 343 holds a magnet 62 ,

A magnet 61 is in the component 32 arranged. By its arrangement on the retaining ring 34 there is a magnet 62 in the magnet holder 343 inside the pressurizable part of the cylinder chamber 21 ,

The retaining ring 34 includes several press-fit pins 341 , The press-fit pins 341 can in blind hole depressions in the seal 31 be pressed. At the end of the press-fit pins 341 there is a thickening 342.

If the thickening 342 in the seal 31 Pressed, this causes the seal 31 in an undercut in the component 32 also thickened and positively in the undercut to the component 32 is attached. By pulling out the press-fit pins 341 out of the seal can the piston 3 in its components 32 and 34 to be shared. The seal can be changed so.

7 shows in a section a two-piece piston 3 a fourth embodiment of the hydraulic cylinder 1 ,

The piston 3 includes a component 32 and a retaining ring 34 , With the retaining ring 34 can a seal 31 at the component 32 be attached.

There is also a magnet holder 343 on the retaining ring 34 arranged, which is a magnet 62 wearing. A magnet 61 is in the component 32 arranged.

The seal 31 is designed as a spreading seal. Through at least one through hole 345 in the retaining ring 34 can fluid out of the cylinder chamber 21 in a cavity 313 the seal 31 reach. By pressure of the fluid is the seal 31 spread apart and an inner sealing lip 314 and an outer sealing lip 315 the seal 31 to the guide surfaces 66 and 67 the cylinder chamber 21 pressed.

8th shows enlarged detail 7 in a cut.

The retaining ring 34 is with ratchet pins 344 provided, which are preferably distributed over its circumference. The ratchet pins 344 carry at their end catches, with which they put in a hole 36 in an end surface, which is the ground 211 the cylinder chamber 21 facing, in the component 32 of the piston 3 can be attached.

By pressing in the locking pins 344 into the component 32 Can be a seal that is between the retaining ring and the component 32 is to be preloaded.

LIST OF REFERENCE NUMBERS

1

Hydraulic cylinder, in particular clutch slave cylinder

2

Housing of the hydraulic cylinder

21

cylinder chamber

211

Bottom of the cylinder chamber

22

Beam

23

sensor support

24

central tube

3

piston

31

Seal, in particular sealing ring

311

Sealing ring with sealing effect inside

312

Sealing ring with sealing effect to the outside

313

cavity

314

Inner sealing lip

315

Outer sealing lip

32

First component of the piston

321

Verdrehsicherungsvorsprung

322

Magnet holder of the first component of the piston

33

Second component of the piston

331

Verdrehsicherungsausnehmung

332

Magnetic holder of the second component of the piston

333

snap hooks

334

anti-rotation

34

retaining ring

341

Insert pin

343

Magnetic holder of the retaining ring

344

Plunger

345

Through Hole

35

overlap area

3532

Ring web of the first component of the piston in the overlap area

3533

Ring web of the second component of the piston in the overlapping area

4

Dirt guard ring

42

projection

43

Magnetic holder

6

magnet

61

First magnet in the piston

62

Second magnet in the piston

63

sensor

64

sensor housing

65

pressure wall

66

Outer guide surface

67

Inner guide surface

7

release spring

8th

outer ring

9

rolling elements

10

inner ring

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

• EP 1898111 B1 [0002]
• DE 10242841 B4 [0003]

Claims (10)

Hydraulic cylinder (1) having a cylinder chamber (21), a cylinder housing (2) and a piston (3) which is at least partially disposed in the cylinder chamber (21) during operation, wherein a magnetic field-sensitive sensor (63) is connected to the cylinder housing (2). is connected, characterized in that at least one magnet (6, 61, 62) is arranged on or in the piston (3), wherein in the operation of the hydraulic cylinder (1) of the sensor (63) for determining a position of the piston (3 ) in the cylinder chamber (21) a magnetic field from the magnet (6, 61, 62) can be detected. Hydraulic cylinder (1) after Claim 1 , characterized in that the guide surface (66, 67) at the same time a sealing counter surface for a seal (31, 311, 312) of the piston (3) for sealing the cylinder chamber (21). Hydraulic cylinder (1) according to one of the preceding claims, characterized in that the magnet (6, 61, 62) is arranged at a position on the piston (3) which in at least one position of the piston (3) within the cylinder chamber ( 21) is located. Hydraulic cylinder (1) according to one of the preceding claims, characterized in that a magnet (6, 61, 62) is arranged at a position on the piston (3) which is located on a permanently pressure-free side of a seal (31, 311, 312 ) is located on the piston (3), and / or a magnet (6, 61, 62) at a location on the piston (3) is arranged on a pressurizable side of the seal (31, 311, 312) on the Piston (3) is located. Hydraulic cylinder (1) according to one of the preceding claims, characterized in that on the piston (3) two separate sealing rings (311, 312) are arranged, each sealingly against one of the guide surfaces (66, 67) of the cylinder chamber (21) In particular, the sealing rings (311, 312) and / or their sealing points are positioned differently in the axial direction of the piston (3). Hydraulic cylinder (1) according to one of the preceding claims, characterized in that the sensor (63) outside the cylinder chamber arranged (21) and with a cylinder housing (2) is connected, wherein a pressure wall (65) of the cylinder housing (2) is arranged to be penetrated by the magnetic field of the magnet (6, 61, 62) in at least one position of the piston (3) such that the magnetic field is receivable by the sensor (63) for measuring the position of the piston (3). Hydraulic cylinder (1) according to one of the preceding claims, characterized in that an anti-twist device is formed between the piston (3) and the cylinder housing (2), in particular in the case of optional multi-parting of the piston (3) an anti-rotation lock between components (32, 33). the piston (3) is arranged, and / or wherein as rotation in particular a positive, axially displaceable engagement of the piston (3) in a recess of the cylinder housing (2) and / or a positive, axially displaceable engagement of the cylinder housing (2) in one Recess of the piston (3) is provided. Hydraulic cylinder (1) according to one of the preceding claims, characterized in that on or in the piston (3) exactly two magnets (61, 62) are arranged at a distance in the axial direction to each other. Hydraulic cylinder (1) according to one of the preceding claims, characterized in that the piston (3) comprises at least two components (32, 33) which are separable from each other in the axial direction (A), preferably between the components (32, 33) in mounted state, a seal (31, 311, 312) is arranged. Hydraulic cylinder (1) after Claim 9 characterized in that a component of the piston (3), which is arranged in the direction of a bottom (211) of the cylinder chamber (21) in the piston (3), as a retaining ring (34) for holding a magnet (62) and / or a seal (31, 311) is formed.

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