Piston assembly and master cylinder for brake system

Abstract

The 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 installed on the circumferential side portion of the piston body in a detachable mode, a concave portion extending in the longitudinal direction (X) is formed on the circumferential side portion of the piston body, and the concave portion is provided with a magnet. A through hole which extends in the radial direction of the piston body, penetrates through the piston body and is communicated with the concave part is formed in the piston body, the magnet assembly comprises a magnet, a shell wrapping the outer side of the magnet and a buckle device formed on one main surface, in the thickness direction (Z), of the magnet assembly, and the buckle device extends away from the magnet and is integrated with the shell. The magnet assembly is received in the recess such that the snap means extends through the through bore in the piston body and forms a snap connection with the piston body at a distal end of the snap means remote from the housing.

Description

Technical Field

[0001] 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

[0002] This section provides background information related to the present application but this information does not necessarily constitute prior art.

[0003] The brake master cylinder, also known as the hydraulic brake master cylinder, is the power source of the vehicle braking system. The connection method between the piston and the magnet in the master cylinder of the existing brake system is mainly through fastening connectors such as bolts and nuts. However, this method of connection through fasteners requires the piston to be pre-processed to obtain the connection structure required for the fastener connection, such as an internal thread structure. Therefore, this connection method has high requirements on processing accuracy, is difficult to process, and has high processing costs. In addition, it has strict requirements on the installation process, generally requires special installation tools, consumes manpower, and has high cost-effectiveness. Summary of the invention

[0004] This section provides a general summary of the application, and is not a comprehensive disclosure of its full scope or all of its features.

[0005] The present invention provides a piston assembly, which includes a columnar 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 a longitudinal direction X is formed on the circumferential side of the piston body. A through hole extending through the piston body in a radial direction of the piston body and connected to the recess is formed in the piston body. 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 a 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.

[0006] Compared with the connection method through fastening connectors in the related art, the piston in the master cylinder connected to the pedal in the brake system of the present application is connected to the housing of the magnet directly attached to the piston body through a snap connection device that is formed as one 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 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.

[0007] 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 lateral direction Y perpendicular to the thickness direction Z of the magnet assembly.

[0008] 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.

[0009] In some optional embodiments, the snap-fit ​​device may be formed as a circumferential snap-fit ​​device, which includes two or more circumferential snap-fit ​​pieces that are equally spaced around the longitudinal center axis of the snap-fit ​​device and extend along the thickness direction Z of the magnet assembly.

[0010] 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.

[0011] 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.

[0012] In some optional embodiments, the buckle device may be a straight-arm buckle device, and the straight-arm buckle device may have two straight-arm buckle parts symmetrically arranged relative to the longitudinal center axis of the buckle device.

[0013] In some optional embodiments, two straight arm snap fasteners may be arranged opposite to each other in a direction parallel to the main surface of the magnet assembly, and each straight arm snap fastener includes a protrusion protruding outward away from the longitudinal center axis of the snap fastener at the top end away from the shell.

[0014] According to the piston assembly of the present application, the magnet assembly is firmly joined 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] In some optional embodiments, a protrusion protruding outward away from the magnet may be provided on the outer circumferential 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.

[0019] In some optional embodiments, the protrusions may be formed as a plurality of ribs disposed on the outer circumferential surface of the housing of the magnet assembly along the circumferential direction, and the plurality of ribs extend in the thickness direction Z along the magnet assembly.

[0020] In some optional embodiments, the size of the protrusion from the housing may be set such 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.

[0021] According to the piston assembly of the present application, a convex portion protruding outward away from the magnet is provided on the outer peripheral surface of the two opposite main surfaces of the connection magnet assembly of the housing in the thickness direction Z, 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. On the one hand, the convex portion can assist in positioning the position of the magnet assembly in the recess, and on the other hand, the convex portion 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 being separated from the recess of the piston body.

[0022] 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.

[0023] In the present application, the protrusion of the snapping member of the snapping device is matched with the seat section, arm joint section and protrusion receiving section of the through hole of the recess of the piston body, so as to firmly join the magnet assembly with the piston body. Compared with the situation in the related art where the magnet assembly is arranged on the outside of the piston body through a connecting member, according to the piston assembly of the present application, the entire magnet assembly is accommodated in the recess of the piston body and firmly joined to the piston body, so that the movement of the magnet assembly is completely consistent with that of the piston body, and then the stroke and speed of the piston assembly can be more accurately detected by detecting the movement of the piston assembly.

[0024] 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 accommodating section, respectively.

[0025] 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, the snap device can be prevented from breaking, and the structural reliability of the snap device is improved.

[0026] 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.

[0027] 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 connected to the pedal in the master cylinder of the brake system of the present application is connected to the housing of the magnet directly attached to the piston body through a snap connection device that is formed as one 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, 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.

[0028] The aspects defined above and further aspects of the present application are apparent from the examples of embodiment described hereinafter and are explained with reference to these examples of embodiment. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The features and advantages of the embodiments of the present application will become more easily understood through the following description with reference to the accompanying drawings, which are not drawn to scale and some features are enlarged or reduced to show details of specific components. In the accompanying drawings:

[0030] Figure 1 shows an exploded schematic diagram of a piston assembly according to an exemplary embodiment of the present application;

[0031] Figure 2 A perspective view of a piston assembly according to an exemplary embodiment of the present application is shown;

[0032] Figure 3 shows a top view of a piston assembly according to an exemplary embodiment of the present application;

[0033] Figure 4A and Figure 4B The piston assembly according to an exemplary embodiment of the present application is shown along Figure 3 A cross-sectional view taken along line AA.

[0034] Figure 5 A schematic diagram of a master cylinder for a brake system according to an exemplary embodiment of the present application is shown. DETAILED DESCRIPTION

[0035] The present application will be described in detail below with reference to the accompanying drawings by means 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 in the various drawings to represent the same components.

[0036] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme 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 part of the embodiments of the present application, rather than all of 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 claimed 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 belong to the scope of protection of the present application.

[0037] It should also be pointed out that, for the sake of clarity, not all features of an actual specific implementation are described and shown in the specification and drawings. In addition, in order to avoid unnecessary details that obscure the technical solutions that the present application focuses on, only the layout structures that are closely related to the technical content of the present application are described and shown in the specification and drawings, while other details that are not closely related to the technical content of the present application and are known to those skilled in the art are omitted.

[0038] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings. However, it will be appreciated by those skilled in the art that in the present application, many technical details are proposed in order 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 scheme claimed in the present application can also be implemented. The division of the following embodiments is for the convenience of description, and the specific implementation of the present application should not be construed as any limitation, and the various embodiments can be combined and referenced with each other under the premise of no contradiction.

[0039] It should be noted that the terms "first", "second", etc. in the specification and claims of the present 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 implying relative importance or implicitly indicating the number of indicated technical features. Thus, the features defined as "first" and "second" can expressly 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 present 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 of their variations 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.

[0040] In the description of the present application, “plurality” means two or more than two, unless otherwise clearly and specifically defined.

[0041] 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 referred device or element 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.

[0042] Next, we will refer to Figures 1 to 4B Exemplary embodiments of a piston assembly according to the present application are described in detail.

[0043] like Figure 1 and Figure 2As shown, 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 extending through the piston body 400 along the radial direction of the piston body 400 and communicating with the recess 406 is formed in the piston body 400. The magnet assembly 500 may include a magnet, a shell 501 coated on 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 .

[0044] 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 brake system of the present application is connected to the housing of the magnet directly attached to the piston body by a snap-on 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-on 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.

[0045] In some embodiments, the housing of the magnet assembly is made of a plastic material, so that the housing of the magnet assembly and the buckle structure can be manufactured into an integral structure by molding. The plastic material used to manufacture the housing of the magnet assembly can be any commercially available high-strength plastic material, as long as it can ensure that the buckle device of the manufactured housing has sufficient strength and elasticity, so that the buckle device can be reliably assembled and disassembled during the assembly and disassembly process due to its high strength and high elasticity.

[0046] 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. Figure 1 and Figure 2As shown, 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, which matches the shape of the strip-shaped magnet assembly. However, the shapes of the magnet housing and the recess of the piston body of the present application can also have any other suitable shapes, such as elliptical and polygonal, and the present application does not limit this, as long as the shapes of the magnet housing 501 and the recess 406 of the piston body 400 can be adapted.

[0047] Continue to refer Figure 1 The housing 501 of the magnet assembly 500 is symmetrically provided with recessed portions 502 recessed inwardly from the outer surface of the housing body, for example, on two side portions along the longitudinal direction X, in the longitudinal direction, wherein a step portion 504 is provided at the bottom of the recessed portion 502 in the circumferential direction of the housing of the magnet assembly. In addition, a recessed portion 503 recessed inwardly 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 step portion 504 of the shell 501 of the magnet and the recessed portion 503 arranged 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.

[0048] In particular, if Figure 1 As shown, a notch 407 is provided on both sides of the transverse direction Y of the piston body 400 at a position corresponding to the central part of the longitudinal length of the magnet housing 501 covered with 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 firmly mounted on 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 notch 407 provided on the recess of the piston body without any adverse effect on the tightness of the piston assembly.

[0049] like Figure 2 As shown, 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.

[0050] 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.

[0051] In the piston assembly 40 according to some embodiments of the present application, as Figure 3 as well as Figure 4A and Figure 4B As shown, 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 cantilever arm 602 extending from the base 601 along the thickness direction Z of the magnet assembly 500; and a protrusion 603 provided at the distal end of the cantilever arm 602 away from the housing 501, the protrusion 603 radially protruding outward from the cantilever 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.

[0052] 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. More specifically, in the 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 protrusion protruding radially outward from the cantilever arm portion 602 is engaged with the protrusion receiving section 403 in the through hole of the piston body (to be described in conjunction with the following) Figure 4A and Figure 4B The magnet assembly is securely fixed to the piston body by abutting the magnet assembly (described in detail).

[0053] It should be understood that the buckle structure in the embodiment of the present application can adopt any suitable type of buckle structure, as long as it can achieve the magnet assembly firmly joined to the piston body, and the present application does not limit this. The buckle device of the magnet assembly of the present application can include but is not limited to a circumferential buckle and a straight arm buckle according to the shape of the buckle.

[0054] A person skilled in the art can set the thickness of the base of the snap-fit ​​device, the length and thickness of the cantilever 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 the magnet assembly to be installed.

[0055] In the piston assembly 40 according to some optional embodiments of the present application, as Figure 1 as well as Figure 4A and Figure 4B As shown, the snap-fit ​​device 600 may be formed as a circumferential snap-fit ​​device, which includes two or more circumferential snap-fit ​​members that are equally spaced around the longitudinal center axis of the circumferential snap-fit ​​device and extend along the thickness direction Z of the magnet assembly 500. In some optional embodiments, each circumferential snap-fit ​​member may include a protrusion 603 that protrudes outward away from the longitudinal center axis of the circumferential snap-fit ​​device at the top end of the circumferential snap-fit ​​member away from the housing 501.

[0056] 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 ​​pieces 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 ​​pieces may be arranged opposite to each other in a direction parallel to the main surface of the magnet assembly 500, and each straight-arm snap-fit ​​piece includes a protrusion protruding outward away from the longitudinal center axis of the straight-arm snap-fit ​​device at the top end of the straight-arm snap-fit ​​piece away from the housing 501.

[0057] In some optional embodiments of the present application, according to different types of snap devices, the through hole in the piston body 400 may have different shapes suitable for the protrusion of the snap device to pass through in the cross section perpendicular to the longitudinal extension direction of the through hole. For example, in some optional embodiments, the through hole in the piston body 400 may have a circular shape in the 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 other optional embodiments, the through hole in the piston body 400 may have a square shape in the 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 the piston assembly of other embodiments of the present application, the magnet assembly is firmly engaged with 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.

[0058] In some optional embodiments of the piston assembly 40 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 (e.g. Figure 4A as shown) and the rounded transition portion (as shown Figure 4B shown).

[0059] In the piston assembly 40 according to some optional embodiments of the present application, a convex portion protruding outward away from the magnet may be provided on 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. 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.

[0060] In the piston assembly 40 according to some embodiments of the present application, a continuous annular convex portion surrounding the outer peripheral surface may be provided on the outer peripheral surface of the two opposite main surfaces of the connection magnet assembly 500 of the housing 501 in the thickness direction Z. For example, the outer peripheral surface of the housing of the magnet assembly may have one or more continuous annular convex portions. In other embodiments, a non-continuous annular convex portion may also be formed on the outer peripheral surface of the housing.

[0061] In the piston assembly 40 according to some other embodiments of the present application, a convex portion extending in the thickness direction Z direction 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 convex ribs provided on the outer peripheral surface of the shell 501 of the magnet assembly 500 in the circumferential direction, and the plurality of convex ribs extend in the thickness direction Z along the magnet assembly 500.

[0062] 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 detaching from the recess of the piston body.

[0063] 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.

[0064] 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 substantially the same as the length of the arm engaging section 402 of the through hole of the piston body 400, thereby enabling the magnet assembly to be securely engaged to the piston body by the protrusion of the snap-fit ​​device directly abutting against the protrusion accommodating section of the piston body.

[0065] like Figures 1 to 4B As shown, 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.

[0066] In the present application, the protrusion of the snapping member of the snapping device is matched with the seat section, arm joint section and protrusion receiving section of the through hole of the recess of the piston body, so as to firmly join the magnet assembly with the piston body. Compared with the situation in the related art where the magnet assembly is arranged on the outside of the piston body through a connecting member, according to the piston assembly of the present application, the entire magnet assembly is accommodated in the recess of the piston body and firmly joined to the piston body, so that the movement of the magnet assembly is completely consistent with that of the piston body, and then the stroke and speed of the piston assembly can be more accurately detected by detecting the movement of the piston assembly.

[0067] In some optional embodiments, transition portions may be provided between the seat section 401 of the through hole and the arm joint section 402 and between the arm joint section 402 of the through hole and the protrusion receiving section 403. In some embodiments, the transition portion may include a ramp-shaped transition portion (e.g. Figure 4A as shown) and the rounded transition portion (as shown Figure 4B shown).

[0068] 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, the snap device can be prevented from breaking, and the structural reliability of the snap device is improved. 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 where the clamping device of the automatic installation equipment is positioned in the through hole, the protrusion of the snap device can be smoothly guided into the through hole through 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.

[0069] Another aspect of the present application further provides a master cylinder 10 for a brake 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.

[0070] In some embodiments of the present application, Figure 5 As shown, the piston assembly 40 is installed in the master cylinder body 11 so that the top of the magnet assembly 500 fixedly mounted on the circumferential side of the piston body 400 in a detachable manner faces the Hall sensor 12, so that the Hall sensor 12 can more accurately detect the stroke or speed of the piston assembly.

[0071] 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 connected to the pedal in the master cylinder of the brake system of the present application is connected to the housing of the magnet directly attached to the piston body through a snap connection device that is formed as one 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, 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.

[0072] 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" etc. 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 representations 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 the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0073] 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. Various changes may be made to the exemplary embodiments by those skilled in the art without departing from the scope defined by the claims of the present disclosure.

[0074] It should also be noted that reference signs in the claims should not be construed as limiting the scope of the claims.

[0075] The features mentioned and / or shown in the above description of the exemplary embodiments of the present disclosure may be combined in the same or similar manner into one or more other embodiments, combined with the features in other embodiments or substituted for the corresponding features in other embodiments. The technical solutions obtained by these combinations or substitutions shall also be deemed to be included in the protection scope 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).

Images