Piston assembly and master cylinder for brake system

Abstract

The present invention provides a piston assembly and a master cylinder for a brake system. The piston assembly comprises a cylindrical piston body and a magnet assembly. The magnet assembly is fixedly mounted on a circumferential side portion of the piston body in a detachable manner. A recessed portion extending in a longitudinal direction (X) is formed on the circumferential side portion of the piston body. A through-hole extending through the piston body in a radial direction of the piston body and communicating with the recessed portion is formed in the piston body. The magnet assembly comprises a magnet, a housing for covering an outer side of the magnet, and a snap-fit device formed on a main surface of the magnet assembly in a thickness direction (Z). The snap-fit device extends away from the magnet and is integrally formed with the housing. The magnet assembly is accommodated in the recessed portion, so that the snap-fit device extends through the through-hole in the piston body and forms a snap-fit connection with the piston body at a distal end portion of the snap-fit device away from the housing.

Description

Piston assembly and master cylinder for brake system

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to Chinese patent application number 202311461776.9 filed with the State Intellectual Property Office of China on November 3, 2023, entitled “Piston assembly and master cylinder for a brake system,” the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The present application generally relates to the technical field of brake systems, and in particular to a piston assembly used in a master cylinder in a brake system and a master cylinder including the piston assembly. Background Art

[0004] This section provides background information related to the present application but does not necessarily constitute prior art.

[0005] The brake master cylinder, also known as the hydraulic master cylinder, is the power source of the vehicle's braking system. In existing brake systems, the piston and magnet in the master cylinder are typically connected using fasteners such as bolts and nuts. However, this method of connection via fasteners requires pre-processing of the piston to obtain the required connection structure, such as an internal thread structure. Therefore, this connection method places high demands on machining accuracy, is difficult to manufacture, and is costly. Furthermore, it places stringent requirements on the installation process, generally requiring special installation tools, which is labor-intensive and cost-effective.

[0006] Summary of the Invention

[0007] This section provides a general summary of the application, and is not a comprehensive disclosure of its full scope or all of its features.

[0008] The present invention provides a piston assembly, which includes a cylindrical piston body and a magnet assembly. The magnet assembly is fixedly mounted on the circumferential side of the piston body in a detachable manner. A recess extending along the longitudinal direction X is formed on the circumferential side of the piston body. A through hole is formed in the piston body, extending through the piston body in the radial direction of the piston body and connected to the recess. The magnet assembly includes a magnet, a shell covering the outside of the magnet, and a snap-fit ​​device formed on a main surface of the magnet assembly along the thickness direction Z. The snap-fit ​​device extends away from the magnet and is integrated with the shell. The magnet assembly is accommodated in the recess so that the snap-fit ​​device extends through the through hole in the piston body and forms a snap-fit ​​connection with the piston body at the distal end of the snap-fit ​​device away from the shell.

[0009] Compared with the connection method through fastening connectors in the related art, the piston in the master cylinder connected to the pedal in the braking system of the present application is connected to the housing of the magnet directly attached to the piston body through a snap-fit ​​connection device that is formed as one piece with the housing of the magnet. The magnet assembly can be easily attached to the through hole of the piston body by the operator pressing the snap-fit ​​device on the housing, so that the magnet assembly can be attached to the piston body very conveniently. The operation is very simple and can be quickly installed without any additional installation tools. Therefore, the installation efficiency is significantly improved and the cost is greatly saved. The magnet assembly is installed on the circumferential side of the piston body, so that the distance between the magnet and the Hall sensor is closer, and the magnetic field sensed by the chip is stronger. The sensitivity of the Hall sensor is higher, and the Hall sensor can detect the stroke or speed of the piston assembly more accurately.

[0010] In some optional embodiments, the snap-fit ​​device of the magnet assembly may include: a base connected to the shell of the magnet assembly; a cantilever arm extending from the base along the thickness direction Z of the magnet assembly; and a protrusion arranged at the distal end of the cantilever arm away from the shell, the protrusion protruding radially outward from the cantilever arm along a transverse direction Y perpendicular to the thickness direction Z of the magnet assembly.

[0011] According to the piston assembly of the present application, the snap-fit ​​device formed as one piece with the housing of the magnet assembly is elastically deformed so that the snap-fit ​​device cooperates with the structure of the through hole of the piston body, thereby reliably connecting the magnet assembly to the piston body.

[0012] In some optional embodiments, the snap-fit ​​device may be formed as a circumferential snap-fit ​​device, comprising two or more circumferential snap-fit ​​members equally spaced around the longitudinal center axis of the snap-fit ​​device and extending along the thickness direction Z of the magnet assembly.

[0013] In some optional embodiments, each circumferential snap member may include a protrusion at a top end away from the housing, the protrusion protruding outward away from the longitudinal center axis of the snap device.

[0014] In some optional embodiments, the through hole in the piston body may have a circular shape in a cross section perpendicular to the longitudinal extension direction of the through hole and may have an inner diameter suitable for inserting the circumferential snap-fit ​​device through the through hole.

[0015] In some optional embodiments, the snap-fit ​​device may be a straight-arm snap-fit ​​device, and the straight-arm snap-fit ​​device may have two straight-arm snap-fit ​​parts symmetrically arranged relative to the longitudinal center axis of the snap-fit ​​device.

[0016] In some optional embodiments, the two straight arm latches can be arranged relative to each other in a direction parallel to the main surface of the magnet assembly, and each straight arm latch includes a protrusion at the top end away from the shell that protrudes outward away from the longitudinal center axis of the latch device.

[0017] According to the piston assembly of the present application, the magnet assembly is firmly coupled to the piston body by matching the protrusion of the snap member of the snap device with the structure of the through hole of the recessed portion of the piston body.

[0018] In some optional embodiments, the through hole in the piston body may have a square shape in a cross section perpendicular to the longitudinal extension direction of the through hole and have a size suitable for inserting the straight arm snap device through the through hole.

[0019] In some optional embodiments, a transition portion connected to the housing of the magnet assembly may be provided at the base of the snap-fit ​​device.

[0020] According to the piston assembly of the present application, a transition portion is provided at the base where the snap-fit ​​device is connected to the housing of the magnet assembly, so as to avoid stress concentration and further enhance the structural reliability of the snap-fit ​​device.

[0021] In some optional embodiments, a protrusion protruding outward away from the magnet may be provided on the outer peripheral surfaces of the two opposite main surfaces of the connecting magnet assembly of the shell in the thickness direction Z, and when the magnet assembly is accommodated in the recess, the protrusion abuts against the circumferential side wall of the recess in the piston body.

[0022] In some optional embodiments, the protrusions may be formed as a plurality of ribs disposed on the outer peripheral surface of the housing of the magnet assembly along the circumferential direction, and the plurality of ribs extend along the thickness direction Z of the magnet assembly.

[0023] In some optional embodiments, the size of the protrusion protruding from the housing may be set so that, when the magnet assembly is accommodated in the recess of the piston body, the magnet assembly forms an interference fit with the recess in the circumferential direction.

[0024] According to the piston assembly of the present application, by providing protrusions protruding outwardly away from the magnets on the outer circumferential surfaces of the two opposite main surfaces of the housing connecting the magnet assembly in the thickness direction Z, the magnet assembly forms an interference fit with the recess in the circumferential direction when the magnet assembly is accommodated in the recess of the piston body. On the one hand, the protrusions can assist in positioning the magnet assembly in the recess, and on the other hand, the protrusions can more tightly secure the magnet assembly in the recess of the piston body through the interference fit, so that even when the brake system vibrates strongly, it can be firmly fixed in the recess without falling out of the recess of the piston body.

[0025] In some optional embodiments, the through hole in the piston body may include, in sequence along the radial direction of the piston body: a seat section located at the bottom of the recess for engaging with the base of the snap device; an arm engaging section for engaging with the cantilevered arm of the snap device; and a protrusion accommodating section for cooperating with and accommodating the protrusion of the snap device near the circumferential surface of the piston body opposite to the recess.

[0026] In the present application, the magnet assembly is securely coupled to the piston body by engaging the protrusion of the snap member of the snap device with the seat section, arm engagement section, and protrusion receiving section of the through hole of the recess of the piston body. Compared with the related art in which the magnet assembly is disposed on the outside of the piston body via a connecting member, the piston assembly of the present application accommodates the entire magnet assembly in the recess of the piston body and securely couples the entire magnet assembly to the piston body, so that the movement of the magnet assembly is completely consistent with that of the piston body, thereby enabling more accurate detection of the stroke and speed of the piston assembly by detecting the movement of the piston assembly.

[0027] In some optional embodiments, transition portions may be provided between the seat section of the through hole and the arm engaging section, and between the arm engaging section and the protrusion receiving section, respectively.

[0028] According to the piston assembly of the present application, by providing a transition portion between the seat section of the through hole on the piston body and the arm joint section and between the arm joint section and the protrusion accommodating section, stress concentration in the channel can be avoided. At the same time, the contact area between the snap device and the piston body can be increased, thereby preventing the snap device from breaking and improving the structural reliability of the snap device.

[0029] The present invention also provides a master cylinder for a braking system, which may include: a master cylinder body; a piston assembly accommodated in the master cylinder body; and a Hall sensor arranged on the side wall of the master cylinder body, wherein the piston assembly is a piston assembly according to any of the aforementioned embodiments, and the Hall sensor is configured to detect the stroke or speed of the piston assembly by detecting the position of a magnet on the piston assembly.

[0030] According to the master cylinder for the brake system of the present application, the magnet assembly is installed on the circumferential side of the piston body, so that the distance between the magnet and the Hall sensor is closer, and the magnetic field sensed by the chip is stronger. The sensitivity of the Hall sensor is higher, and the Hall sensor can detect the stroke or speed of the piston assembly more accurately. The piston in the master cylinder of the brake system of the present application, which is connected to the pedal, is connected to the housing of the magnet directly attached to the piston body through a snap connection device that is integrated with the housing of the magnet. The operator can easily attach the magnet assembly to the through hole of the piston body by pressing the snap device on the housing of the magnet assembly, thereby very conveniently attaching the magnet assembly to the piston body. The operation is very simple and can be quickly installed without the need for any additional installation tools. Therefore, the installation efficiency is significantly improved and the cost is greatly saved.

[0031] The aspects defined above and further aspects of the present application are apparent from and will be elucidated with reference to the examples of embodiment to be described hereinafter. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The features and advantages of the embodiments of the present application will become more readily understood through the following description with reference to the accompanying drawings, which are not drawn to scale and in which some features are exaggerated or minimized to show details of particular components.

[0033] FIG1 shows an exploded schematic diagram of a piston assembly according to an exemplary embodiment of the present application;

[0034] FIG2 shows a perspective view of a piston assembly according to an exemplary embodiment of the present application;

[0035] FIG3 shows a top view of a piston assembly according to an exemplary embodiment of the present application;

[0036] 4A and 4B illustrate cross-sectional views of a piston assembly according to an exemplary embodiment of the present application, taken along line AA of FIG. 3 .

[0037] FIG5 shows a schematic diagram of a master cylinder for a brake system according to an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0038] The present application will be described in detail below with reference to the accompanying drawings by way of exemplary embodiments of the present application. It should be noted that the following detailed description of the present application is for illustrative purposes only and is not intended to limit the present application. In addition, the same reference numerals are used throughout the various drawings to represent the same components.

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application.

[0040] It should also be pointed out that, for the sake of clarity, not all features of an actual specific embodiment are described and shown in the specification and drawings. In addition, in order to avoid unnecessary details that obscure the technical solutions focused on by this application, only the arrangement structures closely related to the technical content of this application are described and shown in the specification and drawings, while other details that are not closely related to the technical content of this application and are known to those skilled in the art are omitted.

[0041] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, each embodiment of the present application will be described in detail below with reference to the accompanying drawings. However, it will be understood by those skilled in the art that in each embodiment of the present application, many technical details are proposed to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can be implemented. The division of the following embodiments is for convenience of description and should not constitute any limitation on the specific implementation of the present application. The various embodiments can be combined and referenced with each other under the premise of no contradiction.

[0042] It should be noted that the terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence, and cannot be understood as indicating or suggesting relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined as "first" and "second" can explicitly or implicitly include one or more of the features. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0043] In the description of the present application, “plurality” means two or more, unless otherwise clearly defined.

[0044] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0045] Next, an exemplary embodiment of a piston assembly according to the present application will be described in detail with reference to FIG. 1 to FIG. 4B .

[0046] As shown in Figures 1 and 2, the piston assembly 40 according to some embodiments of the present application may include a cylindrical piston body 400 and a magnet assembly 500, and the magnet assembly 500 may be fixedly mounted on the circumferential side of the piston body 400 in a detachable manner. A recess 406 extending along the longitudinal direction X may be formed on the circumferential side of the piston body 400. A through hole 405 is formed in the piston body 400, extending through the piston body 400 in the radial direction of the piston body 400 and communicating with the recess 406. The magnet assembly 500 may include a magnet, a shell 501 covering the outside of the magnet, and a snap-fit ​​device 600 formed on a main surface of the magnet assembly 500 along the thickness direction Z. The snap-fit ​​device 600 extends away from the magnet and is integrated with the shell 501. The magnet assembly 500 is received in the recess such that the snap-fit ​​device 600 extends through the through hole in the piston body 400 and forms a snap-fit ​​connection with the piston body 400 at a distal end of the snap-fit ​​device 600 away from the housing 501 .

[0047] Compared with the method of connecting by fastening connectors in the related art, the piston in the master cylinder connected to the pedal in the braking system of the present application is connected to the housing of the magnet directly attached to the piston body through a snap-fit ​​connection device that is integrated with the housing of the magnet. The magnet assembly can be easily attached to the through hole of the piston body by the operator (which can be an automatic installation device) pressing the snap-fit ​​device on the housing, so that the magnet assembly is very conveniently attached to the piston body. The operation is very simple and can be quickly installed without any additional installation tools. Therefore, the installation efficiency is significantly improved and the cost is greatly saved. The magnet assembly is installed on the circumferential side of the piston body, so that the distance between the magnet and the Hall sensor is closer and the magnetic field sensed by the chip is stronger. The sensitivity of the Hall sensor is higher and the Hall sensor can detect the stroke or speed of the piston assembly more accurately.

[0048] In some embodiments, the housing of the magnet assembly is made of a plastic material, so that the housing and the snap-fit ​​structure can be molded into a one-piece structure. The plastic material used to make the housing of the magnet assembly can be any commercially available high-strength plastic material, as long as the snap-fit ​​structure of the housing has sufficient strength and elasticity, thereby ensuring that the snap-fit ​​structure can be reliably assembled and disassembled during assembly and disassembly due to its high strength and high elasticity.

[0049] The recess 406 of the piston body of some embodiments of the present application may have a shape that matches the housing of the magnet assembly. As shown in Figures 1 and 2, the recess 406 of the piston body according to the present application has a strip shape extending along the longitudinal direction X in a plane perpendicular to the radial direction of the piston body that matches the shape of the strip-shaped magnet assembly. However, the shape of the magnet housing and the recess of the piston body of the present application may also have any other suitable shape, for example, an elliptical shape or a polygonal shape, and the present application does not impose any restrictions on this, as long as it can ensure that the shapes of the magnet housing 501 and the recess 406 of the piston body 400 can be adapted.

[0050] 1 , the housing 501 of the magnet assembly 500 is symmetrically provided with recessed portions 502 inwardly recessed from the outer surface of the housing body, for example, on both sides along the longitudinal direction X. A step portion 504 is provided at the bottom of the recessed portions 502 in the circumferential direction of the housing of the magnet assembly. Furthermore, a recessed portion 503 inwardly recessed from the outer surface of the housing body is provided at the top of the housing 501 of the magnet assembly 500, for example, at the center of the top and / or on one or both sides of the top along the longitudinal direction X. By arranging the circumferential recessed portion 502 and the stepped portion 504 on the shell 501 of the magnet and the recessed portion 503 on the top of the shell 501, the expected structural features of the magnet assembly 501 including the magnet and the shell can be obtained, and the materials required for manufacturing the magnet and the shell can be reduced. On the one hand, the cost of manufacturing the piston assembly is saved and the weight of the magnet and the shell is reduced, thereby making the piston assembly including the magnet assembly more lightweight. On the other hand, the magnet can be accurately positioned relative to the mold during the injection molding process of the magnet assembly, thereby significantly improving production efficiency.

[0051] In particular, as shown in FIG1 , notches 407 are provided on both sides of the piston body 400 in the transverse direction Y at positions corresponding to the central portion of the longitudinal length of the magnet housing 501 enclosing the magnet in the recess 406 of the piston body, so that the magnet assembly 500 can be clamped by a clamping device of an automatic mounting device (not shown) and the magnet assembly 500 can be easily and securely mounted to the magnet body by applying a predetermined pressure to the housing 501 by a pressure-applying component of the automatic mounting device. After the installation is completed, the clamping device of the automatic mounting device can easily leave the installed piston assembly through the notches 407 provided on the recess of the piston body without any adverse effect on the tightness of the piston assembly.

[0052] As shown in FIG2 , the surface of the top of the housing 501 of the magnet assembly is flush with or lower than the circumferential surface of the piston body when the magnet assembly has been installed in the piston body, thereby ensuring that the piston assembly can move smoothly in the master cylinder body.

[0053] The structural design of the magnet assembly and the piston body in the piston assembly according to the embodiment of the present application facilitates the automated installation of the piston assembly, significantly improves the installation efficiency, and has high cost-effectiveness.

[0054] In the piston assembly 40 according to some embodiments of the present application, as shown in FIG3 and FIG4A and FIG4B , the snap-fit ​​device 600 of the magnet assembly 500 may include: a base 601 connected to the housing 501 of the magnet assembly 500; a cantilevered arm 602 extending from the base 601 along the thickness direction Z of the magnet assembly 500; and a protrusion 603 provided at a distal end of the cantilevered arm 602 away from the housing 501, the protrusion 603 protruding radially outward from the cantilevered arm 602 along a transverse direction Y perpendicular to the thickness direction Z of the magnet assembly 500. In the embodiment of the present application, the thickness direction Z of the magnet assembly 500 is also the longitudinal extension direction of the snap-fit ​​device 600, and the thickness direction Z of the magnet assembly 500 corresponds to the radial direction of the piston body 400 in the assembled state.

[0055] According to the piston assembly of the present application, the snap-fit ​​device formed as an integral part with the housing of the magnet assembly is elastically deformed so that the snap-fit ​​device cooperates with the structure of the through-hole of the piston body, thereby reliably connecting the magnet assembly to the piston body. More specifically, in an embodiment of the present application, the cantilever arm portion 602 of the snap-fit ​​device 600 of the magnet assembly 500 is elastically deformed during installation into the through-hole of the piston body, and after extending through the entire through-hole of the piston body, the magnet assembly is firmly fixed to the piston body by abutting the protrusion protruding radially outward from the cantilever arm portion 602 with the protrusion receiving section 403 in the through-hole of the piston body (to be described below in conjunction with Figures 4A and 4B).

[0056] It should be understood that the snap-fit ​​structure in the embodiments of the present application may adopt any suitable type of snap-fit ​​structure, as long as it can achieve a secure connection between the magnet assembly and the piston body, and the present application does not impose any restrictions thereto. The snap-fit ​​device of the magnet assembly of the present application may include, but is not limited to, a circumferential snap-fit ​​and a straight-arm snap-fit, depending on the shape of the snap-fit ​​member.

[0057] Those skilled in the art can set the thickness of the base of the snap-fit ​​device, the length and thickness of the cantilevered arm of the snap-fit ​​device, and the thickness of the protrusion of the snap-fit ​​device and the inclination angle of the top of the protrusion according to the relevant parameters of the piston body and magnet assembly to be installed.

[0058] In the piston assembly 40 according to some optional embodiments of the present application, as shown in FIG1 and FIG4A and FIG4B , the snap-fit ​​device 600 may be formed as a circumferential snap-fit ​​device, which includes two or more circumferential snap-fit ​​members arranged at equal intervals around the longitudinal center axis of the circumferential snap-fit ​​device and extending along the thickness direction Z of the magnet assembly 500. In some optional embodiments, each circumferential snap-fit ​​member may include a protrusion 603 at a top end of the circumferential snap-fit ​​member away from the housing 501, which protrudes outwardly away from the longitudinal center axis of the circumferential snap-fit ​​device.

[0059] In the piston assembly 40 according to another optional embodiment of the present application, the snap-fit ​​device 600 may be a straight-arm snap-fit ​​device having two straight-arm snap-fit ​​members symmetrically arranged relative to the longitudinal center axis of the straight-arm snap-fit ​​device. In another optional embodiment, the two straight-arm snap-fit ​​members may be arranged opposite each other in a direction parallel to the main surface of the magnet assembly 500, and each straight-arm snap-fit ​​member includes a protrusion at its top end away from the housing 501 that protrudes outwardly away from the longitudinal center axis of the straight-arm snap-fit ​​device.

[0060] In some optional embodiments of the present application, depending on the different types of snap devices, the through hole in the piston body 400 may have different shapes in a cross section perpendicular to the longitudinal extension direction of the through hole that are suitable for the protrusion of the snap device to pass through. For example, in some optional embodiments, the through hole in the piston body 400 may have a circular shape in a cross section perpendicular to the longitudinal extension direction of the through hole and have an inner diameter suitable for the circumferential snap device to be inserted through the through hole. In another optional embodiment, the through hole in the piston body 400 may have a square shape in a cross section perpendicular to the longitudinal extension direction of the through hole and may have a size suitable for the straight arm snap device to be inserted through the through hole. According to another embodiment of the piston assembly of the present application, the magnet assembly is firmly coupled to the piston body by matching the protrusion of the straight arm snap member of the straight arm snap device with the structure of the through hole of the recess of the piston body.

[0061] In the piston assembly 40 according to some optional embodiments of the present application, a transition portion connected to the housing 501 of the magnet assembly 500 may be provided at the base 601 of the snap-fit ​​device 600. According to the piston assembly of the present application, a transition portion is provided at the base where the snap-fit ​​device is connected to the housing of the magnet assembly to avoid stress concentration and further enhance the structural reliability of the snap-fit ​​device. In some embodiments, the transition portion may include a ramp-shaped transition portion (as shown in FIG. 4A ) and a rounded transition portion (as shown in FIG. 4B ).

[0062] In the piston assembly 40 according to some optional embodiments of the present application, protrusions that protrude outward away from the magnet may be provided on the outer circumferential surfaces of the two opposite main surfaces of the connection magnet assembly 500 of the housing 501 in the thickness direction Z. When the magnet assembly 500 is accommodated in the recess, the protrusions abut against the circumferential sidewalls of the recess in the piston body 400.

[0063] In the piston assembly 40 according to some embodiments of the present application, a continuous annular protrusion surrounding the outer circumferential surface of the two opposite main surfaces of the connection magnet assembly 500 of the housing 501 in the thickness direction Z may be provided. For example, the outer circumferential surface of the housing of the magnet assembly may have one or more continuous annular protrusions. In other embodiments, a discontinuous annular protrusion may also be formed on the outer circumferential surface of the housing.

[0064] In the piston assembly 40 according to some other embodiments of the present application, a convex portion extending along the thickness direction Z of the magnet assembly and protruding outward away from the magnet may be provided on the outer peripheral surface of the two opposite main surfaces of the shell 501 connected to the magnet assembly 500 in the thickness direction Z. For example, one or more convex portions may be symmetrically provided along the longitudinal direction X and / or the transverse direction Y on the outer peripheral surface of the shell of the magnet assembly. In some optional embodiments, the convex portion may be formed as a plurality of ribs provided on the outer peripheral surface of the shell 501 of the magnet assembly 500 in the circumferential direction, and the plurality of ribs extend along the magnet assembly 500 in the thickness direction Z.

[0065] In some optional embodiments, the size of the protrusion from the housing 501 can be set so that: when the magnet assembly 500 is accommodated in the recess of the piston body 400, the magnet assembly 500 forms an interference fit with the recess in the circumferential direction. According to the piston assembly of the present application, by providing a protrusion protruding outward away from the magnet on the outer circumferential surface of the two opposite main surfaces of the connecting magnet assembly of the housing in the thickness direction Z, the magnet assembly forms an interference fit with the recess in the circumferential direction when the magnet assembly is accommodated in the recess of the piston body. On the one hand, the protrusion can assist in positioning the position of the magnet assembly in the recess, and on the other hand, the protrusion can fix the magnet assembly more tightly in the recess of the piston body through interference fit, so that even in the case of strong vibration of the brake system, it can be firmly fixed in the recess without falling off the recess of the piston body.

[0066] In some optional embodiments, the through hole in the piston body 400 may include, in sequence along the radial direction of the piston body 400: a seat section 401 located at the bottom of the recess for engaging with the base 601 of the snap device 600; an arm engaging section 402 for engaging with the cantilevered arm 602 of the snap device 600; and a protrusion accommodating section 403 for cooperating with and accommodating the protrusion 603 of the snap device 600 near the circumferential surface of the piston body 400 opposite to the recess.

[0067] In the piston assembly 40 according to some embodiments of the present application, the length of the cantilevered arm 602 of the snap-fit ​​device 600 of the magnet assembly 500 is approximately the same as the length of the arm engaging section 402 of the through hole of the piston body 400, so that the magnet assembly can be firmly coupled to the piston body by the protrusion of the snap-fit ​​device directly abutting the protrusion accommodating section of the piston body.

[0068] As shown in Figures 1 to 4B, a snap-fit ​​device may be provided in the magnet assembly of the piston assembly in some embodiments of the present application. More specifically, the snap-fit ​​device is provided in the central area of ​​the main surface of the magnet assembly (e.g., the lower main surface in contact with the recess of the piston body) to ensure that the snap-fit ​​device can evenly bear the load. In some other embodiments of the present application, two or more snap-fit ​​devices (not shown) are also provided in the magnet assembly of the piston assembly to further enhance the reliable engagement of the magnet assembly with the piston body. More specifically, a plurality of snap-fit ​​devices are symmetrically provided on the lower main surface of the magnet assembly to ensure that the snap-fit ​​device can evenly bear the load. Those skilled in the art will appreciate that in an embodiment in which two or more snap-fit ​​devices are provided, a plurality of through holes corresponding to the plurality of snap-fit ​​devices are correspondingly provided on the piston body.

[0069] In the present application, the magnet assembly is securely coupled to the piston body by engaging the protrusion of the snap member of the snap device with the seat section, arm engagement section, and protrusion receiving section of the through hole of the recess of the piston body. Compared with the related art in which the magnet assembly is disposed on the outside of the piston body via a connecting member, the piston assembly of the present application accommodates the entire magnet assembly in the recess of the piston body and securely couples the entire magnet assembly to the piston body, so that the movement of the magnet assembly is completely consistent with that of the piston body, thereby enabling more accurate detection of the stroke and speed of the piston assembly by detecting the movement of the piston assembly.

[0070] In some optional embodiments, transition portions may be provided between the through-hole seat section 401 and the arm engagement section 402, and between the through-hole arm engagement section 402 and the protrusion receiving section 403. In some embodiments, the transition portions may include a beveled transition portion (as shown in FIG. 4A ) and a rounded transition portion (as shown in FIG. 4B ).

[0071] According to the piston assembly of the present application, by providing a transition portion between the seat section of the through hole on the piston body and the arm joint section, and between the arm joint section and the protrusion accommodating section, stress concentration in the channel can be avoided, and at the same time, the contact area between the snap device and the piston body can be increased, thereby preventing the snap device from breaking and improving the structural reliability of the snap device. On the other hand, by providing a transition portion between the seat section of the through hole on the piston body and the arm joint section, the protrusion of the snap device can be smoothly guided into the through hole during the installation of the magnet assembly. Even if there is some deviation in the position of the clamping device of the automatic installation equipment positioned in the through hole, the protrusion of the snap device can be smoothly guided into the through hole by the transition portion between the seat section of the through hole and the arm joint section, such as the rounded transition portion, thereby avoiding the situation where the snap device is damaged due to positioning deviation.

[0072] Another aspect of the present application further provides a master cylinder 10 for a braking system, which may include: a master cylinder body 11; a piston assembly 40 accommodated in the master cylinder body 11; and a Hall sensor 12 arranged on the side wall of the master cylinder body 11, wherein the piston assembly 40 is a piston assembly described in any of the aforementioned embodiments, and the Hall sensor 12 is configured to detect the stroke or speed of the piston assembly 40 by detecting the position of the magnet in the piston assembly 40.

[0073] In some embodiments of the present application, as shown in Figure 5, the piston assembly 40 is installed in the master cylinder body 11 so that the top of the magnet assembly 500, which is fixedly mounted on the circumferential side of the piston body 400 in a detachable manner, faces the Hall sensor 12, thereby enabling the Hall sensor 12 to more accurately detect the stroke or speed of the piston assembly.

[0074] According to the master cylinder for the brake system of the present application, the magnet assembly is installed on the circumferential side of the piston body, so that the distance between the magnet and the Hall sensor is closer and the magnetic field sensed by the chip is stronger. The sensitivity of the Hall sensor is higher, and the Hall sensor can detect the stroke or speed of the piston assembly more accurately. The piston in the master cylinder of the brake system of the present application, which is connected to the pedal, is connected to the housing of the magnet directly attached to the piston body through a snap connection device that is integrated with the housing of the magnet. The operator can easily attach the magnet assembly to the through hole of the piston body by pressing the snap device on the housing of the magnet assembly, thereby very conveniently attaching the magnet assembly to the piston body. The operation is very simple and can be quickly installed without the need for any additional installation tools. Therefore, the installation efficiency is significantly improved and the cost is greatly saved.

[0075] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "other embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without mutual contradiction.

[0076] Although the present disclosure has been described with reference to exemplary embodiments, it should be understood that the present disclosure is not limited to the specific embodiments described and shown in detail herein. Those skilled in the art may make various changes to the exemplary embodiments without departing from the scope defined by the claims of the present disclosure.

[0077] It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

[0078] The features mentioned and / or illustrated in the above description of the exemplary embodiments of the present disclosure may be incorporated into one or more other embodiments in the same or similar manner, combined with features in other embodiments, or substituted for corresponding features in other embodiments. The technical solutions obtained by such combination or substitution shall also be deemed to be included within the scope of protection of the present disclosure.

Claims

1. A piston assembly, the piston assembly (40) comprising a cylindrical piston body (400) and a magnet assembly (500), wherein the magnet assembly (500) is fixedly mounted on a circumferential side of the piston body (400) in a detachable manner, characterized in that: A recess extending along the longitudinal direction (X) is formed on the circumferential side of the piston body (400), and a through hole extending along the radial direction of the piston body (400) and penetrating the piston body (400) and connected to the recess is formed in the piston body (400). The magnet assembly (500) includes a magnet, a shell covering the outside of the magnet, and a snap-fit ​​device (600) formed on a main surface of the magnet assembly (500) along the thickness direction (Z), the snap-fit ​​device (600) extending away from the magnet and being integrated with the shell, and the magnet assembly (500) is accommodated in the recess so that the snap-fit ​​device (600) extends through the through hole in the piston body (400) and forms a snap-fit ​​connection with the piston body (400) at the distal end of the snap-fit ​​device (600) away from the shell.

2. The piston assembly according to claim 1, characterized in that The snap-fit ​​device (600) of the magnet assembly (500) comprises: a base (601) connected to the shell of the magnet assembly (500); a cantilever arm (602) extending from the base (601) along the thickness direction (Z) of the magnet assembly (500); and a protrusion (603) arranged at the distal end of the cantilever arm (602) away from the shell, wherein the protrusion (603) protrudes radially outward from the cantilever arm (602) along a transverse direction (Y) perpendicular to the thickness direction (Z) of the magnet assembly (500).

3. The piston assembly according to claim 1 or 2, characterized in that: The snap-fit ​​device (600) is formed as a circumferential snap-fit ​​device, comprising two or more circumferential snap-fit ​​pieces which are arranged at equal intervals around the longitudinal center axis of the circumferential snap-fit ​​device and extend along the thickness direction (Z) of the magnet assembly (500).

4. The piston assembly according to claim 3, characterized in that Each circumferential snap-fit ​​member comprises a protrusion (603) at a top end of the circumferential snap-fit ​​member away from the housing, the protrusion protruding outwardly away from the longitudinal center axis of the circumferential snap-fit ​​device.

5. The piston assembly according to claim 4, characterized in that The through hole in the piston body (400) has a circular shape in a cross section perpendicular to the longitudinal extension direction of the through hole and has an inner diameter suitable for the circumferential snap-fit ​​device to be inserted through the through hole.

6. The piston assembly according to claim 1 or 2, characterized in that: The buckle device (600) is a straight-arm buckle device, and the straight-arm buckle device has two straight-arm buckle parts that are symmetrically arranged relative to the longitudinal center axis of the straight-arm buckle device.

7. The piston assembly according to claim 6, characterized in that Two straight arm snap fasteners are arranged opposite to each other in a direction parallel to the main surface of the magnet assembly (500), and each straight arm snap fastener includes a protrusion protruding outward away from the longitudinal center axis of the straight arm snap fastener at the top end of the straight arm snap fastener away from the shell.

8. The piston assembly according to claim 7, characterized in that The through hole in the piston body (400) has a square shape in a cross section perpendicular to the longitudinal extension direction of the through hole and has a size suitable for the straight arm snap-fit ​​device to be inserted through the through hole.

9. The piston assembly according to claim 2, characterized in that: The base (601) of the snap-fit ​​device (600) is provided with a transition portion connected to the shell of the magnet assembly (500).

10. The piston assembly according to claim 1 or 2, characterized in that: A convex portion protruding outward away from the magnet is provided on the outer peripheral surface of two opposite main surfaces of the shell connecting the magnet assembly (500) in the thickness direction (Z), wherein when the magnet assembly (500) is accommodated in the recess, the convex portion abuts against the circumferential side wall of the recess in the piston body (400).

11. The piston assembly according to claim 10, characterized in that The convex portions are formed as a plurality of convex ribs arranged on the outer peripheral surface of the shell of the magnet assembly (500) in a circumferential direction, and the plurality of convex ribs extend in a thickness direction (Z) along the magnet assembly (500).

12. The piston assembly according to claim 10, characterized in that The dimension of the protrusion protruding from the housing is set so that, when the magnet assembly (500) is accommodated in the recess of the piston body (400), the magnet assembly (500) forms an interference fit with the recess in the circumferential direction.

13. The piston assembly according to claim 2, characterized in that The through hole in the piston body (400) includes, in sequence along the radial direction of the piston body (400): a seat section (401) located at the bottom of the recess for engaging with the base (601) of the snap-fit ​​device (600); an arm engaging section (402) for engaging with the cantilevered arm (602) of the snap-fit ​​device (600); and a protrusion accommodating section (403) for cooperating with and accommodating the protrusion (603) of the snap-fit ​​device (600) near the circumferential surface of the piston body (400) opposite to the recess.

14. The piston assembly according to claim 13, characterized in that Transition portions are respectively provided between the seat section (401) of the through hole and the arm engaging section (402) and between the arm engaging section (402) of the through hole and the protrusion accommodating section (403).

15. A master cylinder for a brake system, the master cylinder (10) comprising: A master cylinder body (11); the piston assembly (40) accommodated in the master cylinder body (11); and a Hall sensor (12) arranged on the side wall of the master cylinder body (11), characterized in that the piston assembly (40) is a piston assembly (40) according to any one of claims 1 to 14, and the Hall sensor (12) is configured to detect the stroke or speed of the piston assembly (40) by detecting the position of the magnet in the piston assembly (40).

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