A MAGNET HOLDER AND STROKE SENSOR WITH THE MAGNET HOLDER

Abstract

A magnet holder for a stroke sensor in which the stroke sensor comprises a magneto-resistive sensor with a magnet and is configured to sense a linear displacement of a plunger in a cylindrical body of a plunger/cylinder arrangement. The magnet holder includes a sleeve enveloping the plunger; a mounting for the magnet radially protruding from the sleeve; and a cover for closing the sleeve on one side comprising an opening for allowing the linear displacement of the plunger. The sleeve and the cover move relative to each other, when the plunger performs the linear displacement in the cylindrical body.

Claims

1-12. (canceled)

13. A magnet holder for a stroke sensor, including a magneto-resistive sensor with a magnet and being configured to sense a linear displacement of a plunger in a cylindrical body of a plunger/cylinder arrangement, comprising: a sleeve enveloping the plunger; a mounting for the magnet radially protruding from the sleeve; and a cover for closing the sleeve on one side comprising an opening for allowing the linear displacement of the plunger, wherein the sleeve and the cover move relative to each other, when the plunger performs the linear displacement in the cylindrical body.

14. The magnet holder of claim 13, wherein the plunger/cylinder arrangement further comprises a piston configured to move together with the plunger inside the cylindrical body, and wherein the sleeve is formed to envelope at least an upper portion of the piston.

15. The magnet holder of claim 13, wherein the plunger is able to perform the linear displacement and/or a rotation relative to the cylindrical body, and wherein the mounting is configured to provide a rotational interlock between the sleeve and the cylindrical body, while allowing the linear displacement within the cylindrical body.

16. The magnet holder of claim 14, wherein the sleeve is adapted to perform the linear displacement together with the plunger and/or the piston.

17. A stroke sensor, comprising: a magneto-resistive sensor with a magnet to sense a linear displacement of a plunger in a cylindrical body of a plunger/cylinder arrangement; and a magnet holder magnet holder, including: a sleeve enveloping the plunger; a mounting for the magnet radially protruding from the sleeve; and a cover for closing the sleeve on one side comprising an opening for allowing the linear displacement of the plunger, wherein the sleeve and the cover move relative to each other, when the plunger performs the linear displacement in the cylindrical body.

18. The stroke sensor of claim 17, further comprising: a chamber arranged at a side portion of the cylindrical body sealed from an interior space of the cylindrical body; and a removable side cover providing a closure for the chamber, wherein the magneto-resistive sensor is arranged together with its magnet inside the chamber.

19. The stroke sensor of claim 18, further comprising: a printed circuit board attached to the removable side cover and adapted to hold the magneto-resistive sensor in the chamber.

20. The stroke sensor of claim 18, wherein the cover is adapted to close the cylindrical body and the chamber.

21. A plunger/cylinder arrangement for a brake system of a vehicle, comprising: a plunger; a cylindrical body within which the plunger is able to perform a linear displacement; and a stroke sensor to generate a sensor signal based/depending on the linear displacement; wherein the stroke sensor includes: a magneto-resistive sensor with a magnet to sense a linear displacement of a plunger in a cylindrical body of a plunger/cylinder arrangement; and a magnet holder magnet holder, including: a sleeve enveloping the plunger; a mounting for the magnet radially protruding from the sleeve; and a cover for closing the sleeve on one side comprising an opening for allowing the linear displacement of the plunger, wherein the sleeve and the cover move relative to each other, when the plunger performs the linear displacement in the cylindrical body.

22. The plunger/cylinder arrangement of claim 21, wherein the cylindrical body includes an axial slot for receiving part of the mounting to provide an axial guidance for the sleeve while preventing relative rotations between the sleeve and the cylindrical body.

23. The plunger/cylinder arrangement of claim 21, further comprising: a piston to move in at least one direction together with the plunger inside the cylindrical body, wherein the sleeve is adapted to slide inside the cylindrical body and to encircle at least an upper portion of piston; and a sealing between a lower portion of the piston and the cylindrical body to seal the chamber from an interior space of the cylindrical body.

24. A vehicle, comprising: a plunger/cylinder arrangement for a brake system of the vehicle, including: a plunger; a cylindrical body within which the plunger is able to perform a linear displacement; and a stroke sensor to generate a sensor signal based/depending on the linear displacement; wherein the stroke sensor includes: a magneto-resistive sensor with a magnet to sense a linear displacement of a plunger in a cylindrical body of a plunger/cylinder arrangement; and a magnet holder magnet holder, including: a sleeve enveloping the plunger; a mounting for the magnet radially protruding from the sleeve; and a cover for closing the sleeve on one side comprising an opening for allowing the linear displacement of the plunger, wherein the sleeve and the cover move relative to each other, when the plunger performs the linear displacement in the cylindrical body.

25. The stroke sensor of claim 17, wherein the magneto-resistive sensor includes a Hall sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG. 1A and FIG. 1B depicts a magnet holder with a stroke sensor for a plunger/cylinder arrangement system according to an embodiment of the present invention.

[0021] FIG. 2 shows a cross-section view of the stroke sensor of FIG. 1A or FIG. 1B along the cross-sectional line A-A.

DETAILED DESCRIPTION

[0022] FIG. 1A and FIG. 1B depict a magnet holder with a stroke sensor for a plunger/cylinder arrangement. The stroke sensor comprises a magneto-resistive sensor 210 with a magnet 220 and the plunger/cylinder arrangement comprises a plunger 310 and a cylindrical body 320 that can move relative to each other along the axial direction M (linear displacement). The magnet holder comprises a sleeve 110 encircling the plunger 310, a mounting 120 for the magnet 220 protruding radially outward from the sleeve 110, and a cover 130 for closing the sleeve 110 on one side. The cover 130 has an opening 135 for allowing the linear displacement of the plunger 310 therethrough. More precisely, the plunger 310 may comprise a plunger rod 312 extending through the opening 135 and a piston part 314 (broadened portion) arranged in an interior space 322 of the cylindrical body 320. The sleeve 110 and the cover 130 move relative to each other, when the plunger 310 performs the linear displacement M through the interior space 322 of the cylindrical body 320.

[0023] In the embodiment of FIG. 1A, the plunger 310 abuts to a piston 330 to push the piston 330 upon the linear displacement M. The plunger/cylinder arrangement may further include at least one spring (not shown in FIG. 1A) to provide a bias force pressing the piston 330 to the plunger 310 (in FIG. 1A upward). It is also possible that the piston 330 couples to the plunger 310 via other coupling elements (e.g. a snap or click connection). The plunger 310 couples likewise to the sleeve 110 preventing a relative displacement of the sleeve 110 and the plunger 310 in the axial direction M. The sleeve 110 may be coupled to the piston 330 rather than to the plunger 310. However, the plunger 310 and the sleeve 110 may rotate relative to each other about the axial direction M. This coupling may be implemented by groove/pin coupling 115 involving e.g. protrusions or a protruding ring extending radially inwards from the sleeve 110 and corresponding recesses or grooves formed at an outer circumference of the plunger 310 or of the piston 330 (or its broadened portion). It may also be implemented the other way around, i.e. the groove/recess is formed in the sleeve 110 and the protrusion(s) on the plunger 310.

[0024] The embodiment depicted in FIG. 1B differs from the embodiment in FIG. 1A only in that the groove/pin coupling 115 involves now the sleeve 110 and the piston 330 (not the plunger). All other components may be arranged in the same way.

[0025] The mounting 120 for the magnet 220 extends radially outwards from the sleeve 110 such that the magnet 220 is held within a chamber 230 separate from the interior space 322 of the cylindrical body 320. The chamber 230 is formed at a side portion of the cylindrical body 320 and is covered by a removable side cover 240. The magneto-resistive sensor 210 is arranged together with the magnet 220 inside the chamber 230, which is sealed from the interior space 322 of the cylindrical body 320 by a sealing arrangement/structure 340 (e.g. a sealing ring). The magneto-resistive sensor 210 may be arranged on a printed circuit board 250 that in turn may be attached to the removable side cover 240 of the chamber 230.

[0026] The cover 130 is adapted to provide a closure for the cylindrical body 320 and the sleeve 110 and/or the chamber 230. The cover 130 is mounted on the cylindrical body 320 and comprises the opening 135 through which the piston rod 312 extends and moves along the linear direction M. Optional sealing elements 137 may be formed between the cover 130 and the piston 310 to provide a sealing during the linear motion M (displacement).

[0027] FIG. 2 shows a cross-sectional view along the cross-sectional line A-A through the piston 330, the sleeve 110, the cylindrical body 320, the magnet 220, and the side cover 240 with the circuit board 250.

[0028] As it is apparent from the cross-sectional view, the sleeve 110 extends through a slot 325 of the cylindrical body 320. This engagement provides a rotational fixation of the sleeve 110 relative to the cylindrical body 320 so that the sleeve 110 is prevented from rotating relative to the cylindrical body 320. As a result, the magnet 120 has to remain at the same angular position in FIG. 2 (the axial displacement M is perpendicular to the drawing plane in FIG. 2). Thus, sensor signals generated by the magneto-resistive element 210 remains in the linear operation range (the linearity is maintained).

[0029] Advantageous aspects of embodiments can be summarized as follows:

[0030] The described arrangement provides a stroke sensor based, e.g., on Hall effect technology for the purpose to provide electrical signal proportional to a stroke of the plunger 310. The sensor is sensitive to magnetic field variation therefore a permanent magnet 220 is placed near the core element of the sensor (e.g. a Hall chip 210), and properly guided to allow a variation of the magnetic field density once the plunger 310 is actuated. Any other direction of movement of the magnet 220 that differs from the direction of the plunger 310 would cause a deviation in the linearity of the sensor signal.

[0031] The plunger 310 and the piston 330 are sliding inside an upper (cylindrical) body 320 together with the sleeve 110 that act as magnet holder (the sleeve 110 and the mounting 120 can be one integral part). The sleeve 110 envelops both the plunger 310 and piston 330 and is open for easy assembly, the opening is opposite oriented with respect to the magnet 220. The magnet holder embraces also the cover 130 and slides on it for the complete stroke of the plunger 310. The sleeve 110 cannot rotate as the magnet seat (mounting 220) moves inside a slot 325 of the upper body 320.

[0032] The magnet holder is configured to deliver three functions: [0033] allow smooth sliding of the plunger 110 and Piston 330 inside the upper body 320; [0034] clamp the magnet 220, move it together with the plunger 310 and avoid transversal movement despite any possible rotation of the plunger 310; [0035] protect the chamber 230, where both the printed circuit board 250 and the magnet 220 are placed.

[0036] The description and drawings merely illustrate the principles of the disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the disclosure and are included within its scope.

[0037] Furthermore, while each embodiment may stand on its own as a separate example, it is to be noted that in other embodiments the defined features can be combined differently, i.e. a particular feature described in one embodiment may also be realized in other embodiments. Such combinations are covered by the disclosure herein unless it is stated that a specific combination is not intended.

THE LIST OF REFERENCE SIGNS IS AS FOLLOWS

[0038] 110 sleeve [0039] 115 protrusion/pin with recess [0040] 120 mounting (support) for the magnet [0041] 130 cover [0042] 135 opening in cover [0043] 137 sealing [0044] 210 magneto-resistive sensor (e.g. Hall sensor) [0045] 220 magnet [0046] 230 chamber [0047] 240 removable side cover [0048] 250 printed circuit board [0049] 310 plunger [0050] 312 plunger rod [0051] 314 piston part of the plunger [0052] 320 cylindrical body [0053] 322 interior space [0054] 325 slot, gap, split-like opening [0055] 330 piston [0056] 340 sealing [0057] M linear displacement