Hydraulic brake master cylinder and hydraulic brake system

Abstract

The hydraulic brake master cylinder and the hydraulic brake system are provided, which comprise a cylinder body provided with a first oil port; a first piston and a second piston which are arranged in the cylinder body to slide in the axial direction; a first pressure cavity and a second pressure cavity which are formed in the cylinder body; and a supplement oil guide part which is arranged on a supplement oil flow path between the first oil port and the second pressure cavity, and comprises a sealing element arranged between the cylinder body and the second piston and a flow passing structure formed on the sealing element, wherein the flow passing structure extends from the side of the sealing element close to the first oil port to the side of the sealing element close to the second pressure cavity. The stability and reliability of the coordinated braking of the foot brake and the hand brake are improved.

Description

Technical Field

[0001] This invention relates to the field of automotive braking technology, and in particular to a hydraulic brake master cylinder and a hydraulic braking system. Background Technology

[0002] Hydraulic braking systems typically need to accommodate foot braking, handbrake braking, and brake force maintenance within a limited installation space. As vehicle braking systems become increasingly integrated, coordinating the pressure transmission path within the master cylinder, and ensuring both reliable sealing and pressure replenishment and maintenance, are key considerations in the structural design of hydraulic brake master cylinders.

[0003] When the foot brake builds up pressure first, followed by the handbrake to compensate, the corresponding pressure chamber in the master cylinder already has foot brake pressure. The handbrake then further compensates for this pressure, increasing braking force. This compensated pressure entering the corresponding pressure chamber may push the corresponding piston in the opposite direction, and as the pressure continues to rise, it may cause a certain degree of retraction of the foot brake-side transmission components. Therefore, it is necessary to further optimize the path of the handbrake-side pressure entering the corresponding pressure chamber, ensuring the compensating pressure capacity while allowing it to enter the chamber in a more controlled manner. This improves the controllability of the handbrake compensation process after the foot brake builds up pressure and enhances the operational stability of the braking system. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a hydraulic brake master cylinder and a hydraulic braking system, which can improve the stability of hydraulic braking.

[0005] This invention provides a hydraulic brake master cylinder, including a cylinder body, which has a first oil port; The first and second pistons are axially slidably disposed within the cylinder body; A first pressure chamber and a second pressure chamber are formed in the cylinder body. The first pressure chamber is located between the first piston and the second piston, and the second pressure chamber is located on the side of the second piston away from the first pressure chamber. The oil replenishment guide is disposed on the oil replenishment flow path between the first oil port and the second pressure chamber. The oil replenishment guide includes a seal disposed between the cylinder and the second piston and a flow passage structure formed on the seal. The flow passage structure extends from the side of the seal near the first oil port to the side of the seal near the second pressure chamber.

[0006] Preferably, it also includes an upstream sealing part, which is disposed between the cylinder body and the second piston, and located between the first oil port and the first pressure chamber, and the upstream sealing part is respectively sealed and cooperated with the cylinder body and the second piston.

[0007] Preferably, the upstream sealing part includes at least two sealing units spaced apart along the axial direction of the second piston, each sealing unit forming a sliding sealing mating surface with the outer periphery of the second piston, and the at least two sealing units are integrally or separately disposed.

[0008] Preferably, the inner wall of the cylinder is provided with an annular mounting groove, which includes a first end wall and a second end wall arranged opposite to each other along the axial direction of the second piston, and a side wall arranged around the second piston in the circumferential direction. The first end wall is located near the first oil port, and the second end wall is located near the second pressure chamber. The sealing element is a lip seal installed in an annular mounting groove. The lip seal includes a connecting base, an inner sealing lip, and an outer elastic sealing lip. The connecting base has a first axial end face on the side near the first oil port, and the first axial end face of the connecting base near the first oil port abuts against the first end wall. The inner sealing lip slides and seals with the outer periphery of the second piston. The outer elastic sealing lip extends from the connecting base toward the second pressure chamber. An outer peripheral flow gap is formed between the outer peripheral surface of the outer elastic sealing lip and the side wall, and an outer flow gap is formed between the free end of the outer elastic sealing lip and the second end wall.

[0009] Preferably, the lip seal is an E-shaped multi-lip seal; The E-shaped multi-lip seal also includes a support lip located between the inner sealing lip and the outer elastic sealing lip, wherein the inner sealing lip, the support lip and the outer elastic sealing lip extend from the connecting base toward the second pressure chamber. An outer lip groove is formed between the outer elastic sealing lip and the support lip, opening towards the second pressure chamber; an inner lip groove is formed between the support lip and the inner sealing lip, opening towards the second pressure chamber. The free end of the supporting lip abuts against the second end wall and can be elastically deflected relative to the second end wall; The free end of the inner sealing lip is spaced apart from the second end wall, and an inner flow gap is formed between the free end of the inner sealing lip and the second end wall.

[0010] Preferably, the flow passage structure includes radial flow channels and multiple axial flow channels; A radial drainage groove is formed on the first axial end face and extends radially along the second piston; Multiple axial flow grooves are formed on the outer peripheral surface of the outer elastic sealing lip and extend along the axial direction of the second piston.

[0011] Preferably, the radial drainage groove extends from the inner periphery of the first axial end face to the outer periphery and communicates with the outer periphery flow gap; Multiple axial flow grooves are arranged circumferentially along the outer elastic sealing lip. The starting end of each axial flow groove near the first oil port is connected to the outer peripheral flow gap. The ending end of each axial flow groove near the second pressure chamber extends to the free end of the outer elastic sealing lip and is connected to the outer lip groove through the outer flow gap.

[0012] Preferably, the plurality of axial flow channels include at least one first axial flow channel and at least one second axial flow channel; The axial distance between the starting end of the first axial flow channel near the first oil port and the first axial end face is the first axial spacing, and the axial distance between the starting end of the second axial flow channel near the first oil port and the first axial end face is the second axial spacing. The first axial spacing is less than the second axial spacing. The termination end of the first axial flow channel near the second pressure chamber and the termination end of the second axial flow channel near the second pressure chamber both extend to the free end of the outer elastic sealing lip.

[0013] Preferably, the second piston has a pressure-replenishing through hole, the inlet of which is located on the outer periphery of the second piston, and the outlet of which is connected to the second pressure chamber. The second piston has a first position and a second position that moves axially relative to the first position; In the first position, the inlet of the pressure-replenishing through hole is opposite to the first oil port, and the first oil port is connected to the second pressure chamber through the pressure-replenishing through hole; In the second position, the inlet of the pressure-replenishing through hole is located on the side of the inner sealing lip near the second pressure chamber, and the inner sealing lip is located between the first oil port and the inlet of the pressure-replenishing through hole.

[0014] The present invention also provides a hydraulic braking system, including the above-described hydraulic brake master cylinder, and further comprising: The foot brake device is connected to the first piston via a transmission mechanism. The handbrake device and the handbrake pump device are connected in a transmission connection, and the handbrake pump device is connected to the first oil port. The second, third, and fourth oil ports are located on the cylinder wall of the cylinder block. The foot brake oil reservoir and the second oil port are connected to the foot brake oil reservoir and the first pressure chamber, respectively. The brake caliper has a third oil port that is connected to the first pressure chamber and the brake caliper, and a fourth oil port that is connected to the second pressure chamber and the brake caliper.

[0015] The beneficial effects of this invention are as follows: by limiting the release of replenishing oil pressure to the first pressure chamber side through the upstream sealing part, the replenishing oil pressure is stably applied to the replenishing oil guide part; by having the first axial flow groove and the second axial flow groove participate in the flow in stages, the replenishing oil flow rate gradually increases with the pressure difference, reducing pressure sudden changes and back thrust risks during replenishing oil; and by limiting the reverse release of pressure oil in the second pressure chamber, the stability and reliability of the coordinated braking of the foot brake and hand brake are improved. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 The diagram shown is a structural schematic of a hydraulic braking system according to an embodiment of the present invention. Figure 2 The diagram shown is a structural schematic of a hydraulic brake master cylinder according to an embodiment of the present invention; Figure 3 The diagram shows a split view of the seal and the second piston in one embodiment of the present invention. Figure 4 The diagram shown is a cross-sectional view of the seal in an annular mounting groove according to an embodiment of the present invention.

[0018] Component designations: 100, Hydraulic brake master cylinder; 10, Cylinder body; 101, Annular mounting groove; 1011, First end wall; 1012, Second end wall; 1013, Side wall; 102, Outer peripheral flow clearance; 103, Outer outer flow clearance; 104, Inner flow clearance; 11, First oil port; 12, Second oil port; 13, Third oil port; 14, Fourth oil port; 20, First piston; 30, Second piston; 301, Pressure compensation through hole; 41, First pressure chamber; 42, ... Two pressure chambers; 51, sealing element; 511, connecting base; 512, inner sealing lip; 513, supporting lip; 514, outer elastic sealing lip; 515, outer lip groove; 516, inner lip groove; 521, radial drainage groove; 5221, first axial flow groove; 5222, second axial flow groove; 60, upstream sealing part; 210, foot brake device; 220, handbrake device; 230, handbrake pump oil device; 240, foot brake oil reservoir; 250, brake caliper. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are all within the scope of protection of this application.

[0020] It should be noted that, in the description of this application, the term "axial" refers to the direction in which the first piston 20 and the second piston 30 reciprocate within the cylinder body 10; "radial" refers to the direction intersecting the axial direction and extending from the axis of the second piston 30 toward its outer periphery; and "circumferential" refers to the direction surrounding the axis of the second piston 30. "The side closer to the first oil port" indicates the side of the corresponding structure facing the first oil port 11 or upstream of the replenishment flow path, and "the side closer to the second pressure chamber" indicates the side of the corresponding structure facing the second pressure chamber 42 or downstream of the replenishment flow path. The above orientational relationships are only used to illustrate the relative positions between the structures and do not limit the installation posture of the hydraulic brake master cylinder 100 in the vehicle.

[0021] This application first provides a hydraulic braking system. The hydraulic braking system includes a hydraulic master cylinder 100 and a brake actuator connected to the hydraulic master cylinder 100. The hydraulic master cylinder 100 outputs hydraulic pressure to the brake actuator to generate braking force. The hydraulic master cylinder 100 can be any of the hydraulic master cylinders described in the following embodiments.

[0022] like Figures 1 to 3 As shown, in some embodiments, the hydraulic brake master cylinder 100 includes a cylinder body 10, a first piston 20, a second piston 30, a first pressure chamber 41, a second pressure chamber 42, and an oil replenishment guide section. The cylinder body 10 has a first oil port 11; the first piston 20 and the second piston 30 are axially slidably disposed within the cylinder body 10; the first pressure chamber 41 and the second pressure chamber 42 are formed within the cylinder body 10, with the first pressure chamber 41 located between the first piston 20 and the second piston 30, and the second pressure chamber 42 located on the side of the second piston 30 opposite to the first pressure chamber 41. The oil replenishment guide section is disposed on the oil replenishment flow path between the first oil port 11 and the second pressure chamber 42. The oil replenishment guide section includes a seal 51 disposed between the cylinder body 10 and the second piston 30, and a flow-through structure formed on the seal 51. The flow-through structure extends from the side of the seal 51 near the first oil port 11 to the side of the seal 51 near the second pressure chamber 42.

[0023] Specifically, a cylinder bore extending axially is formed within the cylinder body 10. A first piston 20 and a second piston 30 are sequentially disposed within the cylinder bore along the axial direction and are capable of reciprocating relative to the inner wall of the cylinder bore. A first pressure chamber 41 is formed by the first piston 20, the second piston 30, and the inner wall of the cylinder bore located between them. A second pressure chamber 42 is formed by the end of the second piston 30 facing away from the first pressure chamber 41 and the corresponding inner wall of the cylinder bore. A first oil port 11 is opened on the cylinder wall of the cylinder body 10 and communicates with the corresponding cylinder bore section on the outer periphery of the second piston 30.

[0024] Furthermore, the seal 51 is disposed around the second piston 30 and located between the first oil port 11 and the second pressure chamber 42. A flow passage structure is formed on the body of the seal 51. The upstream portion of the flow passage structure faces the first oil port 11, and the downstream portion of the flow passage structure faces the second pressure chamber 42, so that the brake fluid entering the upstream side of the seal 51 can cross the axial region where the seal 51 is located along the path formed by the seal 51 itself.

[0025] Optionally, the seal 51 can be an annular seal with one or more elastic lips, or other elastic seals capable of forming a sliding seal between the cylinder 10 and the second piston 30 and carrying the flow passage structure. The flow passage structure can be formed by a continuous groove, or by a combination of interconnected radial grooves, axial grooves, and circumferential grooves. As long as the flow passage structure can extend from the side of the seal 51 near the first oil port 11 to the side of the seal 51 near the second pressure chamber 42, an oil replenishment path can be formed in which the seal 51 itself undertakes the guiding function.

[0026] In one specific embodiment, the foot brake device 210 pushes the first piston 20 to move in the pressure-building direction, compressing the brake fluid in the first pressure chamber 41. The hydraulic pressure in the first pressure chamber 41 pushes the second piston 30 to move in the pressure-building direction, compressing the brake fluid in the second pressure chamber 42. Subsequently, when there is replenishment pressure on the first port 11 side and replenishment is required in the second pressure chamber 42, the brake fluid enters the flow passage structure and flows from the side of the seal 51 near the first port 11 to the side of the seal 51 near the second pressure chamber 42.

[0027] With the above configuration, the key flow passage of the oil replenishment path is integrated into the body of the seal 51. The seal 51 can not only form a sealed separation between the cylinder 10 and the second piston 30, but also limit the oil replenishment path through its own flow passage structure, thereby simplifying the structural correspondence of the oil replenishment path.

[0028] like Figure 2As shown, in some embodiments, the hydraulic brake master cylinder 100 further includes an upstream sealing portion 60. The upstream sealing portion 60 is disposed between the cylinder body 10 and the second piston 30, and is located between the first oil port 11 and the first pressure chamber 41. The upstream sealing portion 60 is in sealing cooperation with the cylinder body 10 and the second piston 30 respectively.

[0029] Specifically, the upstream sealing part 60 is arranged around the second piston 30, with its outer periphery sealingly engaging with the inner wall of the cylinder bore of the cylinder body 10 or a corresponding mounting part, and its inner periphery slidingly sealingly engaging with the outer periphery of the second piston 30. The first oil port 11 is located between the upstream sealing part 60 and the oil replenishment guide part. As a result, the oil replenishment pressure at the first oil port 11 is blocked by the upstream sealing part 60, making it difficult for it to leak to the first pressure chamber 41 along the gap between the second piston 30 and the cylinder body 10.

[0030] Optionally, the upstream sealing part 60 can be installed in an annular groove opened in the inner wall of the cylinder body 10, or it can be held between the cylinder body 10 and the second piston 30 by a pressure ring, shoulder or other axial limiting structure.

[0031] In one specific embodiment, when the handbrake pump 230 outputs brake fluid to the first port 11, the upstream sealing part 60 bears the pressure from the first port 11 side to the first pressure chamber 41 side, and maintains a sealed fit with the cylinder 10 and the second piston 30; the brake fluid at the first port 11 therefore mainly flows toward the replenishment guide part.

[0032] With the above configuration, the upstream sealing part 60 forms an independent sealing boundary between the first oil port 11 and the first pressure chamber 41, so that the oil replenishment pressure at the first oil port 11 can be concentrated on the oil replenishment guide part, reducing the possibility of the oil replenishment pressure being diverted to the first pressure chamber 41 side.

[0033] Continue reading Figure 2 In some embodiments, the upstream sealing portion 60 includes at least two sealing units spaced apart along the axial direction of the second piston 30. Each sealing unit forms a sliding sealing mating surface with the outer periphery of the second piston 30. The at least two sealing units are integrally or separately disposed.

[0034] Specifically, when at least two sealing units are integrally arranged, the upstream sealing portion 60 may include a common annular connecting portion and at least two sub-sealing lips extending from the annular connecting portion toward the outer periphery of the second piston 30. The at least two sub-sealing lips are axially spaced along the second piston 30 and respectively form sliding sealing mating surfaces with the outer periphery of the second piston 30. An annular buffer space is formed between adjacent sub-sealing lips, so that when a small amount of seepage occurs in the sub-sealing lip near the first oil port 11, the sub-sealing lip away from the first oil port 11 can still form a subsequent seal.

[0035] When at least two sealing units are installed separately, each sealing unit is installed at a corresponding mounting position on the inner wall of the cylinder 10, and spaced axially along the second piston 30. Each sealing unit may have an outer peripheral portion that seals with the cylinder 10 and an inner peripheral portion that slides and seals with the second piston 30, with an axial gap maintained between adjacent sealing units. Multiple sealing units may have the same shape, or they may be set separately according to the pressure direction of their respective positions.

[0036] In one specific embodiment, the upstream sealing part 60 adopts an integrally formed double-lip sealing structure. The first sub-sealing lip, which is closer to the first oil port 11, performs the main sealing, while the second sub-sealing lip, which is farther away from the first oil port 11, forms an auxiliary seal. The two sub-sealing lips together restrict the flow of brake fluid at the first oil port 11 to the first pressure chamber 41.

[0037] With the above configuration, at least two axially spaced sealing units form multiple sliding seals between the first oil port 11 and the first pressure chamber 41. Even if one of the seals leaks locally due to wear or transient deformation, the other seal can still continue to limit the release of replenishing oil pressure.

[0038] like Figures 3 to 4 As shown, in some embodiments, the inner wall of the cylinder 10 is provided with an annular mounting groove 101. The annular mounting groove 101 includes a first end wall 1011 and a second end wall 1012 arranged opposite each other along the axial direction of the second piston 30, and a side wall 1013 arranged circumferentially around the second piston 30. The first end wall 1011 is located near the first oil port 11, and the second end wall 1012 is located near the second pressure chamber 42. The sealing member 51 is a lip seal installed in the annular mounting groove 101. The lip seal includes a connecting base 511, an inner sealing lip 512, and an outer elastic sealing lip 514. The connecting base 511 has a first axial end face on the side near the first oil port 11, and the first axial end face abuts against the first end wall 1011. The inner sealing lip 512 slides and seals with the outer periphery of the second piston 30. An outer elastic sealing lip 514 extends from the connecting base 511 toward the second pressure chamber 42. An outer peripheral flow gap 102 is formed at least locally between the outer peripheral surface of the outer elastic sealing lip 514 and the sidewall 1013, and an outer flow gap 103 is formed between the free end of the outer elastic sealing lip 514 and the second endwall 1012. The outer peripheral surface of the outer elastic sealing lip 514 may also have a variable contact area that elastically abuts against the sidewall 1013, so that the effective axial range of the outer peripheral flow gap 102 changes with the elastic deformation of the outer elastic sealing lip 514.

[0039] Specifically, the annular mounting groove 101 is formed in the inner wall of the cylinder bore of the cylinder body 10 and surrounds the second piston 30. The first end wall 1011 and the second end wall 1012 respectively define the axial mounting position of the lip seal, and the side wall 1013 is located between the two and defines the radially outer position of the lip seal. The connecting base 511 is an annular base, and the first axial end face fits against the first end wall 1011, so that the brake fluid reaching the inner peripheral area of ​​the annular mounting groove 101 from the first oil port 11 side needs to flow to the outer peripheral area of ​​the connecting base 511 through the corresponding flow portion formed on the first axial end face.

[0040] Furthermore, the inner sealing lip 512 extends from the connecting base 511 toward the second pressure chamber 42, and its free end elastically presses against the outer periphery of the second piston 30, thereby forming a dynamic sealing boundary between the seal 51 and the second piston 30. The outer elastic sealing lip 514 is located radially outside the inner sealing lip 512, its root is connected to the connecting base 511, and its free end faces the second end wall 1012. The outer peripheral flow gap 102 includes an initial gap portion near the connecting base 511 and communicating with the radial drainage groove 521, and a variable gap portion that is formed or expanded by gradually separating from the side wall 1013 under the action of fluid pressure; the outer flow gap 103 extends between the free end of the outer elastic sealing lip 514 and the second end wall 1012.

[0041] Optionally, the outer elastic sealing lip 514 includes an outer root portion connected to the connecting base 511 and an outer free end portion near the second end wall 1012. The thickness of the outer root portion is greater than the thickness of the outer free end portion. The outer elastic sealing lip 514 can be continuously thinned along its extension direction or can be thinned in segments. The thicker root portion is used to maintain the support stability of the outer elastic sealing lip 514, while the thinner free end is used to enable the outer elastic sealing lip 514 to undergo controlled elastic deformation according to the fluid pressure within the outer peripheral flow gap 102. The outer peripheral surface of the outer elastic sealing lip 514 can also be inclined relative to the axis of the second piston 30, so that the radial dimension of the outer peripheral flow gap 102 varies along the axial direction.

[0042] In one specific embodiment, the first axial end face of the connecting base 511 continuously abuts against the first end wall 1011. An initial gap is maintained between the outer peripheral surface of the outer elastic sealing lip 514 near the connecting base 511 and the side wall 1013, and another section of the outer peripheral surface of the outer elastic sealing lip 514 extending towards the free end forms an elastic abutment with the side wall 1013 with a pre-compression amount. Brake fluid flows from the inner peripheral region of the connecting base 511 to the outer peripheral region and first enters the initial gap; as the replenishment pressure difference increases, the elastic abutment area gradually detaches from the side wall 1013 from the end near the connecting base 511 towards the free end, forming or expanding a variable gap. The brake fluid then flows through the axial flow groove and the outer flow gap 103 to the side of the seal 51 near the second pressure chamber 42.

[0043] With the above configuration, the annular mounting groove 101, the connecting base 511, the inner sealing lip 512 and the outer elastic sealing lip 514 together define the installation position of the seal 51 and the spatial boundary of the oil replenishment flow path; the outer peripheral flow gap 102 and the outer flow gap 103 respectively support the upstream and downstream sections of the flow structure, so that the flow structure can bypass the contact area between the connecting base 511 and the first end wall 1011 and lead the brake fluid to the second pressure chamber 42 side.

[0044] Continue reading Figures 3 to 4 In some embodiments, the lip seal is an E-shaped multi-lip seal. The E-shaped multi-lip seal also includes a support lip 513 located between the inner sealing lip 512 and the outer elastic sealing lip 514. The inner sealing lip 512, support lip 513, and outer elastic sealing lip 514 extend from the connecting base 511 toward the second pressure chamber 42. An outer lip groove 515 opening toward the second pressure chamber 42 is formed between the outer elastic sealing lip 514 and the support lip 513, and an inner lip groove 516 opening toward the second pressure chamber 42 is formed between the support lip 513 and the inner sealing lip 512. The free end of the support lip 513 abuts against the second end wall 1012 and is elastically deflectable relative to the second end wall 1012. The free end of the inner sealing lip 512 is spaced apart from the second end wall 1012, and an inner flow gap 104 is formed between the free end of the inner sealing lip 512 and the second end wall 1012.

[0045] Specifically, the connecting base 511 forms the common root of the E-shaped multi-lip seal, and the outer elastic sealing lip 514, the support lip 513, and the inner sealing lip 512 are arranged radially from the outside to the inside. The outer lip groove 515 is located between the outer elastic sealing lip 514 and the support lip 513, and the inner lip groove 516 is located between the support lip 513 and the inner sealing lip 512. Both the outer lip groove 515 and the inner lip groove 516 open toward the second end wall 1012, but they are separated by the contact area between the support lip 513 and the second end wall 1012 when the free end of the support lip 513 remains in contact.

[0046] Furthermore, the support lip 513 includes a support root connected to the connecting base 511 and a support free end for abutting against the second end wall 1012. The thickness of the support root is greater than the thickness of the support free end, and the thickness of the support lip 513 gradually decreases in the direction toward the free end. At least one surface of the support lip 513 can be inclined relative to the axial direction, so that its deformation mainly occurs near the free end. When the pressure in the outer lip groove 515 is greater than the pressure in the inner lip groove 516 and a corresponding pressure difference condition is reached, the free end of the support lip 513 elastically deflects toward the inner lip groove 516, and a temporary communication gap is formed between the free end of the support lip 513 and the second end wall 1012.

[0047] After the brake fluid enters the outer lip groove 515 through the outer flow gap 103, it acts on the surface of the support lip 513 facing the outer lip groove 515. When the support lip 513 deflects, the brake fluid bypasses the free end of the support lip 513 and enters the inner lip groove 516, then enters the downstream space near the second pressure chamber 42 on the outer periphery of the second piston 30 through the inner flow gap 104 between the free end of the inner sealing lip 512 and the second end wall 1012. When the pressure difference decreases, the support lip 513 returns to its original position due to its elasticity, and its free end re-abuts the second end wall 1012.

[0048] Optionally, both the outer elastic sealing lip 514 and the support lip 513 can gradually thin from the connecting base 511 toward their respective free ends, but the degree of thinning and the thickness of the free ends can differ. The thinning structure of the outer elastic sealing lip 514 is used to improve the elastic compliance of the free end while maintaining root stability; the thinning structure of the support lip 513 is used to form a free end deflection controlled by pressure difference. The degree of thinning of the support lip 513 can be greater than that of the outer elastic sealing lip 514, so that the support lip 513 can bear the pressure difference opening and closing action.

[0049] In one specific embodiment, the free end of the support lip 513 has an axial preload pointing towards the second end wall 1012 under normal conditions, forming an annular contact band. When the pressure in the outer lip groove 515 increases, the support lip 513 first undergoes local bending near its free end. As the pressure difference increases, the communication gap between the free end of the support lip 513 and the second end wall 1012 gradually expands; when the pressure difference decreases, the communication gap gradually shrinks and eventually closes.

[0050] In one feasible material and variation example, the E-shaped multi-lip seal is made of EPDM rubber compatible with non-petroleum-based brake fluids, with a rubber hardness of Shore A 65 to 75. Both the outer elastic sealing lip 514 and the support lip 513 have a cross-section that is thicker at the root and thinner at the free end. The free end of the support lip 513 remains elastically pressed against the second end wall 1012 after being inserted into the annular mounting groove 101. The aforementioned hardness range is only used to illustrate one feasible material selection range; the actual hardness, root thickness, free end thickness, and preload are determined jointly based on the brake fluid type, operating temperature, target replenishment pressure differential, and the dimensions of the annular mounting groove 101.

[0051] To enable the support lip 513 to handle downstream pressure differential opening and closing while the outer elastic sealing lip 514 handles upstream staged flow guidance, the free end bending stiffness of the support lip 513 is set to be less than the overall radial yield stiffness of the variable contact area of ​​the outer elastic sealing lip 514. Thus, after brake fluid is received in the outer lip groove 515, the support lip 513 can locally deflect within the pressure differential range where it effectively participates in the flow no later than the first axial flow groove 5221; the outer elastic sealing lip 514 gradually expands its disengagement range axially as the pressure differential continues to increase. This stiffness relationship can be achieved by adjusting the effective length, root thickness, free end thickness, and installation preload of the two lips respectively.

[0052] With the above configuration, a pressure differential conduction path is formed inside the E-shaped multi-lip seal, consisting of the outer lip groove 515, the free end of the support lip 513, the inner lip groove 516, and the inner flow gap 104. The support lip 513 can remain in contact when the second pressure chamber 42 is pressurized, and can elastically deflect when the second pressure chamber 42 experiences relatively low pressure and the first oil port 11 side has replenishment pressure, thereby continuing to guide the brake fluid delivered by the flow structure to the second pressure chamber 42.

[0053] like Figure 3 and Figure 4 As shown, in some embodiments, the flow passage structure includes a radial flow channel 521 and a plurality of axial flow channels. The radial flow channel 521 is formed on the first axial end face and extends radially along the second piston 30; the plurality of axial flow channels are formed on the outer peripheral surface of the outer elastic sealing lip 514 and extend axially along the second piston 30.

[0054] Specifically, the radial drainage groove 521 is a groove recessed on the first axial end face. When the first axial end face abuts against the first end wall 1011, the groove wall of the radial drainage groove 521 and the first end wall 1011 together form a radial flow channel, allowing the brake fluid to flow between the inner and outer peripheral regions of the connecting base 511. The axial flow groove is a groove recessed on the outer peripheral surface of the outer elastic sealing lip 514, and the groove wall of the axial flow groove and the side wall 1013 of the annular mounting groove 101 together form an axial flow channel.

[0055] Furthermore, the radial drainage groove 521 and the axial flow groove together form a continuous but directionally changing composite flow path. The brake fluid first flows along the radial drainage groove 521 from the inner circumference of the connecting base 511 to the outer circumference, then enters the outer circumferential flow gap 102, and then turns to enter the corresponding axial flow groove, flowing along the outer circumferential surface of the outer elastic sealing lip 514 towards its free end. The radial drainage groove 521 is used to cross the axial contact area between the connecting base 511 and the first end wall 1011, and the axial flow groove is used to cross the axially extending area of ​​the outer elastic sealing lip 514.

[0056] Optionally, the radial drainage groove 521 can be a single groove or multiple grooves spaced circumferentially along the first axial end face. Multiple axial flow grooves can be connected to a single circumferential connecting section or individually connected to their corresponding radial drainage grooves 521. The cross-sections of the radial drainage grooves 521 and the axial flow grooves can be arc-shaped, semi-circular, trapezoidal, rectangular, or V-shaped. A rounded transition is preferably used between the bottom and wall of each groove to reduce local resistance during brake fluid flow and avoid stress concentration at sharp corners.

[0057] In one specific embodiment, four radially spaced drainage grooves 521 are provided on the first axial end face, and eight axially spaced drainage grooves are provided on the outer circumferential surface of the outer elastic sealing lip 514. The outer circumferential end of each radially spaced drainage groove 521 communicates with the outer circumferential drainage gap 102 where at least two axially spaced drainage grooves are located, thereby allowing brake fluid entering from different circumferential positions to be dispersed into multiple axially spaced drainage grooves. The above quantity is merely an example and does not limit the numerical relationship between the radially spaced drainage grooves 521 and the axially spaced drainage grooves.

[0058] The depth of the radial flow channel 521 and the axial flow channel can be from 0.10 mm to 0.40 mm, preferably from 0.15 mm to 0.30 mm; the width can be from 0.30 mm to 1.00 mm, preferably from 0.40 mm to 0.70 mm. The channel depth is used to determine the basic flow cross-section of a single channel and affects the remaining thickness of the lip after slotting, while the channel width is used to determine the flow cross-section of a single channel and the circumferential width of the adjacent unslotted outer peripheral support area. The channel depth and width should be determined based on the oil replenishment flow rate, while ensuring the remaining strength and circumferential continuity of the outer elastic sealing lip 514.

[0059] The total effective flow cross-section of the multiple radial flow channels 521 is not less than the total effective flow cross-section of the axial flow channels at the corresponding stage; the effective flow cross-sections of the outer flow gap 103, the temporary connecting gap formed after the deflection of the support lip 513, and the inner flow gap 104 match the total effective flow cross-section of the axial flow channels to avoid the radial flow channels 521 or the downstream gap becoming fixed throttling bottlenecks. The effective flow cross-section of the pressure-replenishing through-hole 301 is also determined based on the target throughput when all axial flow channels participate in the flow. Here, "matching" does not require that the values ​​of each cross-section be equal, but rather that under the target oil replenishment pressure difference, the addition of the second axial flow channel 5222 can actually increase the effective throughput of the entire oil replenishment flow path.

[0060] With the above configuration, the radial drainage groove 521 and the axial flow groove respectively undertake the functions of radial drainage and axial conveying, so that the flow structure forms a continuous flow path with a clear direction relationship on the body of the seal 51, and the flow position of the brake fluid is dispersed by multiple axial flow grooves.

[0061] Continue reading Figure 3 and Figure 4 In some embodiments, the radial drainage groove 521 extends from the inner periphery of the first axial end face to the outer periphery and communicates with the outer peripheral flow gap 102. Multiple axial flow grooves are spaced circumferentially along the outer elastic sealing lip 514. The starting end of each axial flow groove near the first oil port 11 communicates with the outer peripheral flow gap 102, and the terminating end of each axial flow groove near the second pressure chamber 42 extends to the free end of the outer elastic sealing lip 514 and communicates with the outer lip groove 515 via the outer flow gap 103.

[0062] Specifically, the inner peripheral end of the radial drainage groove 521 opens onto the inner peripheral edge of the first axial end face and faces the annular fluid space between the first oil port 11 and the upstream sealing part 60; the outer peripheral end of the radial drainage groove 521 opens onto the outer peripheral edge of the first axial end face and faces the outer peripheral flow gap 102. Thus, the brake fluid at the first oil port 11 can enter the radial drainage groove 521 from the inner peripheral side of the seal 51, and then enter the outer peripheral flow gap 102 from the outer peripheral end of the radial drainage groove 521.

[0063] The starting end of each axial flow groove is located on the outer peripheral surface of the outer elastic sealing lip 514 near the connecting base 511, and is connected to the outer peripheral flow gap 102; the ending end of each axial flow groove extends axially to the free end of the outer elastic sealing lip 514, so that the axial flow groove forms an outlet facing the outer flow gap 103 at the free end. After the brake fluid flows out from the outlet of the axial flow groove, it enters the outer lip groove 515 through the outer flow gap 103.

[0064] Optionally, multiple axial flow channels can be equidistantly arranged circumferentially, or they can be non-equidistantly arranged according to the force and flow distribution around the annular mounting groove 101. An ungrooved outer circumferential support area is retained between adjacent axial flow channels to maintain the circumferential continuity of the outer elastic sealing lip 514. The terminating end of the axial flow channel can be flush with the free end of the outer elastic sealing lip 514, or it can form a flared section at the free end that opens outwards to the flow gap 103.

[0065] In one specific embodiment, the radial drainage groove 521 extends along the entire radial width of the first axial end face, and the axial flow groove extends along the outer peripheral surface of the outer elastic sealing lip 514 to the free end. During operation, the brake fluid sequentially passes through the "annular space on the side of the first oil port 11—radial drainage groove 521—outer peripheral flow gap 102—axial flow groove—outer flow gap 103—outer lip groove 515", and then the support lip 513 controls whether it continues to enter the inner lip groove 516.

[0066] With the above settings, the oil replenishment path is continuously connected between the upstream side, outer peripheral side and downstream side of the seal 51 to form a complete oil replenishment path.

[0067] like Figure 3 and Figure 4 As shown, in some embodiments, the plurality of axial flow channels include at least one first axial flow channel 5221 and at least one second axial flow channel 5222. The axial distance between the starting end of the first axial flow channel 5221 near the first oil port 11 and the first axial end face is a first axial spacing L1, and the axial distance between the starting end of the second axial flow channel 5222 near the first oil port 11 and the first axial end face is a second axial spacing L2. The first axial spacing L1 is smaller than the second axial spacing L2. The terminating end of the first axial flow channel 5221 near the second pressure chamber 42 and the terminating end of the second axial flow channel 5222 near the second pressure chamber 42 both extend to the free end of the outer elastic sealing lip 514.

[0068] Specifically, the first axial flow channel 5221 and the second axial flow channel 5222 have axially offset upstream starting ends and downstream terminating ends located in the same free end region. Since the first axial distance L1 is smaller than the second axial distance L2, the starting end of the first axial flow channel 5221 is closer to the connecting base 511 and the first axial end face than the starting end of the second axial flow channel 5222; when the terminating ends of both types of channels are located at free ends, the axial length of the first axial flow channel 5221 is greater than the axial length of the second axial flow channel 5222.

[0069] It should be noted that different starting positions and axial lengths can create different flow path lengths and flow resistances. To make the first axial flow channel 5221 and the second axial flow channel 5222 form a more clearly defined hierarchical flow relationship, in a preferred embodiment, an effective flow area that gradually expands axially is formed between the outer peripheral surface of the outer elastic sealing lip 514 and the sidewall 1013, and an intermediate elastic contact area is retained between the starting end of the first axial flow channel 5221 and the starting end of the second axial flow channel 5222.

[0070] Specifically, the peripheral flow gap 102 includes an upstream gap section near the first axial end face and communicating with the radial drainage groove 521, and a variable gap section that can expand axially under fluid pressure. The outer peripheral surface of the outer elastic sealing lip 514 can adopt an inclined tapering structure, with its section near the connecting base 511 first radially contracting inward. As the pressure inside the peripheral flow gap 102 increases, the effective separation boundary between the outer elastic sealing lip 514 and the sidewall 1013 expands towards the free end. The starting end of the first axial flow groove 5221 is located at the position first reached by the effective separation boundary, and the starting end of the second axial flow groove 5222 is located at the position reached after the effective separation boundary.

[0071] The first axial flow channel 5221 and the second axial flow channel 5222 are circumferentially offset, with a continuous ungrooved outer circumferential surface remaining between them. This continuous outer circumferential surface maintains elastic contact with the sidewall 1013 at least before the second axial flow channel 5222 participates in the flow, thereby restricting the brake fluid from flowing directly from the circumferential position of the first axial flow channel 5221 to the starting end of the second axial flow channel 5222. In this embodiment, the outer circumferential flow gap 102 is a flow space formed or expanded by the deformation of the outer elastic sealing lip 514, and it has different effective axial ranges under different pressure differential conditions.

[0072] Under a relatively small replenishment pressure differential, the outer elastic sealing lip 514, near the connecting base 511, first deflects radially inward, and the effective flow area reaches the starting end of the first axial flow groove 5221. After the brake fluid enters the outer peripheral flow gap 102 through the radial guide groove 521, it first enters the first axial flow groove 5221 and flows along the first axial flow groove 5221 towards the free end; at this time, the intermediate elastic abutment area still restricts the brake fluid from entering the starting end of the second axial flow groove 5222.

[0073] As the pressure differential continues to increase, the deflection area of ​​the outer elastic sealing lip 514 expands axially, and the effective flow area crosses the intermediate elastic abutment area and reaches the starting end of the second axial flow channel 5222. The second axial flow channel 5222 thus joins the oil supply path, and the first axial flow channel 5221 and the second axial flow channel 5222 together deliver brake fluid to the outer flow gap 103. When the pressure differential decreases, the outer elastic sealing lip 514 resets in the opposite direction, and the starting end of the second axial flow channel 5222 exits the effective flow area first, followed by the starting end of the first axial flow channel 5221.

[0074] Optionally, the widths of the first axial flow channel 5221 and the second axial flow channel 5222 can be the same, so that the difference between the two types of channels is mainly determined by the starting position; the widths can also be different, with the first axial flow channel 5221 set to a smaller width to form a basic oil replenishment flow, and the second axial flow channel 5222 set to a larger width to increase the oil replenishment flow under a larger pressure differential. The first axial flow channel 5221 and the second axial flow channel 5222 can be alternately arranged circumferentially, and continuous outer peripheral support areas are respectively provided on both sides of the circumference of each first axial flow channel 5221 to maintain the overall support strength of the outer elastic sealing lip 514.

[0075] In one specific embodiment, the first axial spacing L1 is 10% to 25% of the axial length of the outer elastic sealing lip 514, the second axial spacing L2 is 30% to 55% of the axial length, and both the first axial flow groove 5221 and the second axial flow groove 5222 extend to the free end of the outer elastic sealing lip 514.

[0076] Further, the axial distance between the starting ends of the first axial flow channel 5221 and the second axial flow channel 5222 is denoted as G, and the larger channel width of the first axial flow channel 5221 and the second axial flow channel 5222 is denoted as W. In a preferred embodiment, G satisfies W ≤ G ≤ 2W. When G is less than W, the two types of starting ends are too close, and a small deformation of the outer elastic sealing lip 514 may cause the two types of channels to participate in the flow approximately simultaneously; when G is greater than 2W, the second axial flow channel 5222 may only participate in the flow after the outer elastic sealing lip 514 has undergone a large deformation, making the first stage last too long.

[0077] In a specific dimensional example of a hydraulic brake master cylinder 100 with a nominal bore diameter of 19 mm, four radial drainage grooves 521 are provided, each with a depth of 0.20 mm and a width of 0.60 mm; eight axial flow grooves are provided, four of which are first axial flow grooves 5221 and the other four are second axial flow grooves 5222, and they are alternately distributed circumferentially. The first axial flow grooves 5221 have a depth of 0.20 mm and a width of 0.50 mm, and the second axial flow grooves 5222 have a depth of 0.20 mm and a width of 0.60 mm; the first axial spacing L1 is 0.80 mm, and the second axial spacing L2 is 1.60 mm, therefore the axial distance G between the two types of starting ends is 0.80 mm, and satisfies W≤G≤2W. Both types of axial flow grooves extend to the free end of the outer elastic sealing lip 514, and the groove bottom and groove wall adopt a rounded transition.

[0078] Furthermore, the opening pressure difference of the support lip 513 is preferably not higher than the pressure difference at which the first axial flow channel 5221 forms an effective flow passage, or the support lip 513 and the first axial flow channel 5221 form an effective passage approximately simultaneously. Thus, when the first axial flow channel 5221 participates in the flow first, the brake fluid flowing into the outer lip groove 515 can push the support lip 513 to deflect and enter the inner lip groove 516; when the pressure difference further increases, the second axial flow channel 5222 joins in the flow, forming a larger total flow cross section.

[0079] With the above configuration, the first axial flow channel 5221 and the second axial flow channel 5222 not only have different path lengths, but also participate in the flow in stages with the gradual deflection of the outer elastic sealing lip 514 and the cooperation of the middle elastic abutment area. The first axial flow channel 5221 first provides the basic oil replenishment passage, and the second axial flow channel 5222 then increases the oil replenishment flow, so that the oil replenishment flow rate gradually increases with the pressure difference.

[0080] like Figures 2 to 4 As shown, in some embodiments, the second piston 30 has a pressure-replenishing through-hole 301. The inlet of the pressure-replenishing through-hole 301 is located on the outer periphery of the second piston 30, and the outlet of the pressure-replenishing through-hole 301 communicates with the second pressure chamber 42. The second piston 30 has a first position and a second position that moves axially relative to the first position. In the first position, the inlet of the pressure-replenishing through-hole 301 is opposite to the first oil port 11, and the first oil port 11 communicates with the second pressure chamber 42 through the pressure-replenishing through-hole 301. In the second position, the inlet of the pressure-replenishing through-hole 301 is located on the side of the inner sealing lip 512 near the second pressure chamber 42, and the inner sealing lip 512 is located between the first oil port 11 and the inlet of the pressure-replenishing through-hole 301.

[0081] Specifically, the pressure-replenishing through-hole 301 may include a radial section extending from the outer periphery of the second piston 30 toward its interior and an axial section extending from the radial section toward the second pressure chamber 42. The inlet is formed at the outer opening of the radial section, and the outlet is formed at the opening of the axial section toward the second pressure chamber 42. The pressure-replenishing through-hole 301 may also be a single channel extending obliquely relative to the axis of the second piston 30, as long as the inlet is located on the outer periphery of the second piston 30 and the outlet communicates with the second pressure chamber 42.

[0082] When the second piston 30 is in the first position, it is in a non-pressure-building initial position, and the inlet of the pressure-replenishing through-hole 301 is radially opposite to the first oil port 11. The brake fluid at the first oil port 11 can directly enter the inlet and flow into the second pressure chamber 42 through the pressure-replenishing through-hole 301.

[0083] After the second piston 30 moves from the first position to the second position along the pressure-building direction, the inlet of the pressure-replenishing through-hole 301 passes over the inner sealing lip 512 and is located on the side of the inner sealing lip 512 close to the second pressure chamber 42. At this time, the inner sealing lip 512 is located between the first oil port 11 and the inlet and maintains a sliding seal with the outer periphery of the second piston 30. The first oil port 11 can no longer directly enter the inlet along the outer periphery of the second piston 30. The brake fluid at the first oil port 11 needs to pass through the radial drainage groove 521, the outer peripheral flow gap 102, the first axial flow groove 5221 and the second axial flow groove 5222, the outer flow gap 103, the outer lip groove 515, the temporary connecting gap formed by the deflection of the support lip 513, the inner lip groove 516, and the inner flow gap 104 in sequence to reach the inlet located downstream of the inner sealing lip 512, and then enter the second pressure chamber 42 through the pressure-replenishing through-hole 301.

[0084] Optionally, the second position can be a position within the pressure-building stroke of the second piston 30, or it can be a range of positions from when the second piston 30 passes the inner sealing lip 512 to when it reaches the predetermined maximum stroke. The inlet of the pressure-replenishing through-hole 301 can be directly opened on the cylindrical outer circumferential surface of the second piston 30, or it can be opened at the bottom of a local shallow groove on the outer circumference of the second piston 30, which can expand the circumferential receiving range of the inlet.

[0085] In one specific embodiment, when the second piston 30 is in the first position, it forms a normal direct oil replenishment. After the foot brake device 210 drives the second piston 30 into the second position, the inner sealing lip 512 cuts off the direct path from the first oil port 11 to the inlet of the pressure replenishment hole 301. When the second pressure chamber 42 experiences a relatively low pressure and the first oil port 11 has a high oil replenishment pressure, the brake fluid reaches the inlet of the pressure replenishment hole 301 through the composite flow structure of the seal 51 itself and the pressure difference deflection path of the support lip 513, thereby continuing to replenish brake fluid to the second pressure chamber 42 when the second piston 30 is in the pressure-building position.

[0086] With the above configuration, the same pressure-replenishing through-hole 301 can form different oil replenishment paths corresponding to two positions of the second piston 30: in the first position, oil is directly replenished by the first oil port 11, and in the second position, oil is replenished by the oil replenishment guide portion bypassing the inner sealing lip 512. Thus, even after the movement of the second piston 30 causes the direct oil replenishment path to be blocked by the inner sealing lip 512, an oil replenishment path can still be established through the flow structure formed on the seal 51.

[0087] like Figure 1 As shown, in some embodiments, the hydraulic braking system includes the aforementioned hydraulic brake master cylinder 100, and further includes a foot brake device 210, a handbrake device 220, a handbrake pump device 230, a foot brake reservoir 240, and a brake caliper 250. The cylinder body is also provided with a second oil port 12, a third oil port 13, and a fourth oil port 14. The foot brake device 210 is drivenly connected to the first piston 20; the handbrake device 220 is drivenly connected to the handbrake pump device 230, and the handbrake pump device 230 is connected to the first oil port 11. The second oil port 12, the third oil port 13, and the fourth oil port 14 are formed on the cylinder wall of the cylinder body 10; the second oil port 12 is connected to the foot brake reservoir 240 and the first pressure chamber 41, respectively; the third oil port 13 is connected to the first pressure chamber 41 and the brake caliper 250, respectively; and the fourth oil port 14 is connected to the second pressure chamber 42 and the brake caliper 250, respectively.

[0088] Specifically, the foot brake device 210 can be connected to the first piston 20 via a push rod or other transmission component. When the foot brake device 210 is operated, the transmission component pushes the first piston 20 to move in the pressure-building direction. The handbrake device 220 can be a handbrake lever, handbrake pedal, or electronic handbrake actuator. The handbrake device 220 causes the handbrake pump device 230 to pump oil via a mechanical transmission component or an electric drive component. The oil outlet of the handbrake pump device 230 is connected to the first oil port 11 via a pipeline.

[0089] The foot brake reservoir 240 is connected to the first pressure chamber 41 via a pipeline and the second port 12, and is used to replenish the first pressure chamber 41 with brake fluid. The third port 13 connects the first pressure chamber 41 to the corresponding brake caliper 250 via the first brake pipeline, and the fourth port 14 connects the second pressure chamber 42 to the corresponding brake caliper 250 via the second brake pipeline. The brake caliper 250 may include multiple brake calipers respectively installed at different wheels, and the first pressure chamber 41 and the second pressure chamber 42 may be connected to different brake circuits respectively.

[0090] Under normal foot brake operation, the driver operates the foot brake device 210, which pushes the first piston 20 to move in the pressure-building direction. The first piston 20 compresses the brake fluid in the first pressure chamber 41 and outputs hydraulic pressure to the corresponding brake caliper 250 through the third port 13. The hydraulic pressure in the first pressure chamber 41 simultaneously acts on the second piston 30, causing the second piston 30 to move in the pressure-building direction and compress the brake fluid in the second pressure chamber 42. The second pressure chamber 42 outputs hydraulic pressure to the corresponding brake caliper 250 through the fourth port 14.

[0091] When the second piston 30 is in the first position and the handbrake pump 230 outputs brake fluid, the first port 11 is opposite to the inlet of the pressure replenishing hole 301. The brake fluid enters the pressure replenishing hole 301 directly from the first port 11 and then enters the second pressure chamber 42 from the outlet. The hydraulic pressure in the second pressure chamber 42 acts on the corresponding brake caliper 250 through the fourth port 14.

[0092] When the foot brake device 210 applies initial braking and then continues to apply additional handbrake pressure, the first piston 20 and the second piston 30 have already moved along the pressure-building direction. The second piston 30 is in the second position, and the inlet of the pressure-replenishing through-hole 301 is located on the side of the inner sealing lip 512 near the second pressure chamber 42. The inner sealing lip 512 thus cuts off the original oil replenishment path of the first oil port 11 directly entering the pressure-replenishing through-hole 301 through the outer periphery of the second piston 30. At this time, the handbrake device 220 drives the handbrake pump device 230 to pump brake fluid to the first oil port 11. Since the upstream sealing part 60 is located between the first oil port 11 and the first pressure chamber 41, and is sealed and cooperated with the cylinder body 10 and the second piston 30 respectively, the upstream sealing part 60 can limit the brake fluid and replenishment pressure at the first oil port 11 from being released unintended to the first pressure chamber 41 side along the gap between the cylinder body 10 and the second piston 30. This allows the replenishment pressure generated by the handbrake pump 230 to act more concentratedly on the replenishment guide part, and to form a replenishment pressure difference between the first oil port 11 side and the second pressure chamber 42 side.

[0093] Brake fluid at the first port 11 enters the inner circumference of the connecting base 511 and flows to the outer circumferential flow gap 102 via the radial drainage groove 521. When the replenishment pressure difference reaches the first stage condition, the portion of the outer elastic sealing lip 514 near the connecting base 511 first elastically retracts, allowing the effective flow area of ​​the outer circumferential flow gap 102 to reach the starting end of the first axial flow groove 5221. Brake fluid preferentially enters the first axial flow groove 5221 and then enters the outer lip groove 515 via the outer flow gap 103. The support lip 513 elastically deflects under the pressure difference between the outer lip groove 515 and the inner lip groove 516, allowing brake fluid to bypass the free end of the support lip 513 and enter the inner lip groove 516, then sequentially enter the second pressure chamber 42 via the inner flow gap 104 and the pressure replenishment through hole 301.

[0094] During the first stage of oil replenishment, the first axial flow channel 5221 provides an initial oil replenishment path with a limited effective flow cross-section, while the second axial flow channel 5222 has not yet participated in the flow. Therefore, the brake fluid output from the handbrake pump 230 will not enter the second pressure chamber 42 with a large flow rate immediately after the replenishment flow path is formed. This limits the amount of brake fluid entering the second pressure chamber 42 during the initial stage of pressure replenishment, allowing the pressure within the second pressure chamber 42 and the reverse force acting on the second piston 30 to increase more smoothly, reducing the possibility of sudden reverse movement of the second piston 30 and sudden retraction of the foot brake side transmission component.

[0095] As the pressure differential increases further, the effective deflection range of the outer elastic sealing lip 514 continues to expand axially. The effective flow area of ​​the outer peripheral flow gap 102 crosses the intermediate elastic contact area and reaches the starting end of the second axial flow groove 5222, adding a replenishing flow path to the second axial flow groove 5222 on top of the first axial flow groove 5221 already participating in the flow. The brake fluid enters the outer lip groove 515 through the first axial flow groove 5221 and the second axial flow groove 5222, and enters the pressure replenishing through hole 301 along the deflection path of the support lip 513, ultimately replenishing the second pressure chamber 42. The hydraulic pressure in the second pressure chamber 42 is transmitted to the corresponding brake caliper 250 through the fourth oil port 14. Thus, the replenishing guide section can gradually increase the replenishing capacity when the pressure replenishment demand increases, limiting the replenishing flow rate in the initial stage of pressure replenishment while ensuring the brake fluid flow rate required for subsequent handbrake pressure replenishment.

[0096] During the aforementioned oil replenishment process, the first axial flow channel 5221 and the second axial flow channel 5222 do not simultaneously provide full flow capacity when the oil replenishment flow path is formed. Instead, they participate in the flow in stages as the oil replenishment pressure difference increases and the elastic clearance range of the outer elastic sealing lip 514 expands, causing the effective flow cross section of the oil replenishment flow path to gradually expand from the restricted initial flow cross section. As a result, the handbrake-side replenishment pressure can be connected to the second pressure chamber 42 through the oil replenishment path with the flow capacity expanding in stages. While ensuring the handbrake replenishment capacity, this reduces the possibility of a large replenishment flow suddenly entering the second pressure chamber 42 in a short period of time. This allows the pressure in the second pressure chamber 42 and the reverse force acting on the second piston 30 to increase more controllably, thereby reducing the risk of sudden reverse movement of the second piston 30 and sudden retraction of the foot brake-side transmission component. This improves the operational controllability and working stability when the foot brake builds up pressure first and then the handbrake replenishes pressure.

[0097] When the handbrake pumping device 230 stops pumping oil and the oil replenishment pressure difference between the first oil port 11 and the second pressure chamber 42 decreases, the outer elastic sealing lip 514 gradually resets, the second axial flow groove 5222 exits the effective flow state first, and the first axial flow groove 5221 exits the effective flow state later; the support lip 513 resets itself elastically and abuts against the second end wall 1012 again, so that the temporary communication gap between the outer lip groove 515 and the inner lip groove 516 is closed.

[0098] Furthermore, when the pressure in the second pressure chamber 42 is higher than the pressure on the first oil port 11 side, the pressurized oil in the second pressure chamber 42 can enter the pressurized through-hole 301 from the outlet and flow out from the inlet of the pressurized through-hole 301, and then enter the inner lip groove 516 through the inner flow gap 104. The pressurized oil entering the inner lip groove 516 acts on the inner sealing lip 512 and the support lip 513, causing the free end of the inner sealing lip 512 to be further pressed against the outer periphery of the second piston 30, and causing the free end of the support lip 513 to maintain contact with the second end wall 1012. Therefore, the temporary communication gap between the free end of the support lip 513 and the second end wall 1012 remains closed, the inner lip groove 516 and the outer lip groove 515 are isolated from each other, and the pressure oil in the second pressure chamber 42 cannot cross the support lip 513 to enter the outer lip groove 515, and thus cannot flow back to the first oil port 11 in sequence through the outer flow gap 103, the axial flow groove, the outer peripheral flow gap 102 and the radial flow channel 521.

[0099] With the above settings, the support lip 513 has different engagement states under the action of forward oil replenishment pressure difference and reverse pressure build-up pressure difference: when the pressure on the first oil port 11 side is higher than the pressure in the second pressure chamber 42, the free end of the support lip 513 is elastically deflected relative to the second end wall 1012, so that the outer lip groove 515 is connected to the inner lip groove 516; when the pressure in the second pressure chamber 42 is higher than the pressure on the first oil port 11 side, the free end of the support lip 513 remains in contact with the second end wall 1012, so that the outer lip groove 515 is isolated from the inner lip groove 516, so that the oil replenishment flow route is unidirectionally guided from the first oil port 11 to the second pressure chamber 42, and prevents the pressure oil in the second pressure chamber 42 from being released in reverse.

[0100] In summary, this embodiment reduces the risk of unintended leakage of brake fluid and replenishment pressure from the handbrake pump 230 to the first pressure chamber 41 by sealing the flow gap between the first oil port 11 and the first pressure chamber 41 side through the upstream sealing part 60, thus ensuring that the replenishment pressure acts more stably on the replenishment guide part. The radial drainage groove 521, the first axial flow groove 5221, and the second axial flow groove 5222 cooperate with the elastic relief of the outer elastic sealing lip 514 to allow the effective flow cross section of the replenishment flow path to expand in stages with the change of the replenishment pressure difference, and deliver the brake fluid to the second pressure chamber 42 through the pressure difference deflection of the support lip 513. Therefore, when the second piston 30 is in the pressure-building position, it can still replenish oil to the second pressure chamber 42, and reduce the possibility of sudden pressure change in the second pressure chamber 42 caused by a sudden increase in the replenishment flow. This reduces the risk of sudden back thrust to the second piston 30 and the foot brake side transmission component during the handbrake pressure replenishment process, and improves the stability and operational controllability when the foot brake builds up pressure first and then the handbrake replenishes pressure. At the same time, the support lip 513 can also remain in contact with the second end wall 1012 under the action of reverse pressure difference, limiting the reverse release of pressurized oil in the second pressure chamber 42 to the first oil port 11 side.

[0101] The technical features in the above embodiments can be combined with each other without contradiction; any equivalent substitutions or conventional modifications made to the shape, quantity, relative position or connection method of each structure without departing from the concept of this application shall be included within the protection scope of this application.

Claims

1. A hydraulic brake master cylinder, characterized in that, include: The cylinder block has a first oil port; The first piston and the second piston are axially slidably disposed within the cylinder body; A first pressure chamber and a second pressure chamber are formed in the cylinder body. The first pressure chamber is located between the first piston and the second piston, and the second pressure chamber is located on the side of the second piston away from the first pressure chamber. An oil replenishment guide is provided on the oil replenishment flow path between the first oil port and the second pressure chamber. The oil replenishment guide includes a seal provided between the cylinder and the second piston and a flow passage structure formed on the seal. The flow passage structure extends from the side of the seal near the first oil port to the side of the seal near the second pressure chamber.

2. The hydraulic brake master cylinder according to claim 1, characterized in that, It also includes an upstream sealing part, which is disposed between the cylinder body and the second piston, and located between the first oil port and the first pressure chamber. The upstream sealing part is respectively sealed and cooperates with the cylinder body and the second piston.

3. The hydraulic brake master cylinder according to claim 2, characterized in that, The upstream sealing part includes at least two sealing units spaced apart along the axial direction of the second piston. Each sealing unit forms a sliding sealing mating surface with the outer periphery of the second piston. The at least two sealing units are integrally or separately disposed.

4. The hydraulic brake master cylinder according to claim 1, characterized in that, The inner wall of the cylinder is provided with an annular mounting groove. The annular mounting groove includes a first end wall and a second end wall that are arranged opposite each other along the axial direction of the second piston, and a side wall that is arranged around the second piston in the circumferential direction. The first end wall is located near the first oil port, and the second end wall is located near the second pressure chamber. The sealing element is a lip seal installed in the annular mounting groove, and the lip seal includes a connecting base, an inner sealing lip, and an outer elastic sealing lip. The connecting base has a first axial end face on the side near the first oil port, and the first axial end face of the connecting base near the first oil port abuts against the first end wall. The inner sealing lip is in sliding sealing engagement with the outer periphery of the second piston; The outer elastic sealing lip extends from the connecting base toward the second pressure chamber. An outer peripheral flow gap is formed between the outer peripheral surface of the outer elastic sealing lip and the sidewall, and an outer flow gap is formed between the free end of the outer elastic sealing lip and the second endwall.

5. The hydraulic brake master cylinder according to claim 4, characterized in that, The lip seal is an E-shaped multi-lip seal; The E-shaped multi-lip seal also includes a support lip located between the inner sealing lip and the outer elastic sealing lip, wherein the inner sealing lip, the support lip, and the outer elastic sealing lip extend from the connecting base toward the second pressure chamber. An outer lip groove is formed between the outer elastic sealing lip and the supporting lip, opening towards the second pressure chamber; and an inner lip groove is formed between the supporting lip and the inner sealing lip, opening towards the second pressure chamber. The free end of the supporting lip abuts against the second end wall and can be elastically deflected relative to the second end wall; The free end of the inner sealing lip is spaced apart from the second end wall, and an inner flow gap is formed between the free end of the inner sealing lip and the second end wall.

6. The hydraulic brake master cylinder according to claim 5, characterized in that, The flow passage structure includes radial flow channels and multiple axial flow channels; The radial drainage groove is formed on the first axial end face and extends radially along the second piston; Multiple axial flow grooves are formed on the outer peripheral surface of the outer elastic sealing lip and extend along the axial direction of the second piston.

7. The hydraulic brake master cylinder according to claim 6, characterized in that, The radial drainage groove extends from the inner periphery of the first axial end face to the outer periphery and communicates with the outer periphery flow gap; The plurality of axial flow grooves are arranged circumferentially along the outer elastic sealing lip. The starting end of each axial flow groove near the first oil port is connected to the outer peripheral flow gap. The terminating end of each axial flow groove near the second pressure chamber extends to the free end of the outer elastic sealing lip and is connected to the outer lip groove through the outer flow gap.

8. The hydraulic brake master cylinder according to claim 7, characterized in that, The plurality of axial flow channels include at least one first axial flow channel and at least one second axial flow channel; The axial distance between the starting end of the first axial flow groove near the first oil port and the first axial end face is the first axial spacing, and the axial distance between the starting end of the second axial flow groove near the first oil port and the first axial end face is the second axial spacing. The first axial spacing is less than the second axial spacing. The termination end of the first axial flow groove near the second pressure chamber and the termination end of the second axial flow groove near the second pressure chamber both extend to the free end of the outer elastic sealing lip.

9. The hydraulic brake master cylinder according to claim 5, characterized in that, The second piston has a pressure-replenishing through hole, the inlet of which is located on the outer periphery of the second piston, and the outlet of which is connected to the second pressure chamber; The second piston has a first position and a second position that is axially movable relative to the first position; At the first position, the inlet of the pressure-replenishing through hole is opposite to the first oil port, and the first oil port is connected to the second pressure chamber through the pressure-replenishing through hole; In the second position, the inlet of the pressure-replenishing through hole is located on the side of the inner sealing lip near the second pressure chamber, and the inner sealing lip is located between the first oil port and the inlet of the pressure-replenishing through hole.

10. A hydraulic braking system, characterized in that, Including the hydraulic brake master cylinder as described in any one of claims 1 to 9, further comprising: The foot brake device is connected to the first piston via a transmission. A handbrake device and a handbrake pump device, wherein the handbrake device and the handbrake pump device are connected in a transmission connection, and the handbrake pump device is connected to the first oil port; The second, third, and fourth oil ports are located on the cylinder wall of the cylinder body; The foot brake oil reservoir is connected to the foot brake oil reservoir and the first pressure chamber, respectively. The brake caliper has a third oil port that is connected to the first pressure chamber and the brake caliper, and a fourth oil port that is connected to the second pressure chamber and the brake caliper.

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