Brake master cylinder and linked brake system

Abstract

The application relates to the technical field of braking, in particular to a brake master cylinder and a linkage braking system. The brake master cylinder comprises a pump body, a first piston, a second piston and a piston push rod; the pump body is provided with a piston cavity, a first oil guide hole and a second oil guide hole; the first oil guide hole is communicated with a second chamber, the second oil guide hole is communicated with a third chamber, the first oil guide hole is used for being communicated with a foot brake pump body, and the second oil guide hole is used for being connected with a front brake or a rear brake; the piston push rod is connected with the pump body and is transmissionally connected with the first piston, and the piston push rod is used for driving the first piston to move under the driving action of an external force; wherein the second piston is used for moving in the direction of the second oil guide hole under the driving action of the first piston or the pressure action of the second chamber, so that the front brake or the rear brake brakes. The brake master cylinder can simplify the structure of the linkage braking system and reduce the use cost of the linkage braking system.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of braking, in particular to a brake master cylinder and a linkage braking system. BACKGROUND

[0002] The braking system is an essential safety component of an all-terrain vehicle, including a front brake assembly and a rear brake assembly. Generally, the front and rear brake assemblies are independently actuated, but in order to obtain greater deceleration, some all-terrain vehicles are also equipped with a linkage braking system. In order to meet the braking operation needs of different riders, the all-terrain vehicle braking system should meet the requirements that the front and rear brakes can be independently braked, and the front and rear brakes can be braked in linkage. In order to achieve the above-mentioned braking effect, a three-circuit braking system needs to be set up, that is, the left master cylinder drives the rear brake independently, the right master cylinder drives the front brake independently, and the foot brake master cylinder drives the front and rear brakes to realize linkage braking. In order to realize the three-circuit braking, the prior art adopts the form of connecting a hydraulic valve in the braking system, but such a setting mode not only increases the cost of the braking system, but also leads to a complex structure of the braking system. SUMMARY

[0003] The purpose of the present application is to provide a brake master cylinder which can simplify the structure of the linkage braking system and reduce the use cost of the linkage braking system.

[0004] The embodiment of the present application is implemented as follows:

[0005] A brake master cylinder, comprising a pump body, a first piston, a second piston and a piston push rod;

[0006] The pump body is provided with a piston cavity, a first oil guide hole and a second oil guide hole; the first piston and the second piston are slidably accommodated in the piston cavity along the axis of the piston cavity, and the first piston and the second piston abut; the first piston and the second piston jointly divide the piston cavity into a first chamber, a second chamber and a third chamber; the first chamber is located at one end of the first piston away from the second piston, the second chamber is located at the outer periphery of the second piston, and the second chamber is blocked from the first chamber and the third chamber, and the third chamber is located at one end of the second piston away from the first chamber; the first oil guide hole is in communication with the second chamber, and the second oil guide hole is in communication with the third chamber; the first oil guide hole is used to communicate with the foot brake pump body, and the second oil guide hole is used to connect with the front brake or the rear brake;

[0007] The piston push rod is connected with the pump body and in transmission connection with the first piston, and is used to drive the first piston to move under the driving action of an external force;

[0008] The second piston is used to move towards the direction of the second oil guide hole under the driving action of the first piston or the pressure action of the second chamber, so as to brake the front brake or the rear brake.

[0009] In one embodiment of the present application, the first piston is provided with a mounting groove at one end thereof facing the second piston, and the second piston is provided with a mounting groove at one end thereof facing the first piston.

[0010] In one embodiment of the present application, the brake master cylinder further comprises a first restoring member, which is accommodated in the third chamber and is configured to cause the second piston to have a tendency to move towards the first piston.

[0011] In one embodiment of the present application, the brake master cylinder further comprises a limiting rod, which is connected to the pump body; the first piston is provided with a strip-shaped hole which is in sliding cooperation with the limiting rod; and the limiting rod cooperates with the strip-shaped hole to limit the movement of the first piston.

[0012] In one embodiment of the present application, the pump body further comprises a blocking member; the pump body further comprises an oil pool; the first piston and the second piston are respectively provided with a first oil guide channel and a second oil guide channel, the first oil guide channel and the second oil guide channel are in communication; the first oil guide channel is in communication with the oil pool, and the second oil guide channel is in communication with the third chamber.

[0013] The blocking member is connected to the second piston, and is configured to open or block the second oil guide channel and the third chamber.

[0014] In one embodiment of the present application, the blocking member comprises a piston cover, a movable member and a second restoring member.

[0015] The piston cover is accommodated in the third chamber and is connected to the second piston, and the movable member and the second restoring member are arranged in the piston cover; the second restoring member is configured to cause the movable member to have a tendency to block the second oil guide channel at one end thereof facing the third chamber.

[0016] When the second piston moves towards the third chamber, the movable member is blocked by the hydraulic pressure of the third chamber and the action of the second restoring member.

[0017] When the second piston moves towards the first chamber, the second oil guide channel is opened by the hydraulic pressure of the first chamber or the first restoring member.

[0018] In one embodiment of the present application, the piston cover is provided with a through hole which is in communication with the third chamber.

[0019] In one embodiment of the present application, the movable member comprises a sliding rod; a part of the sliding rod is located in the second oil guide channel and is in slidable cooperation with the second oil guide channel, and the rest of the sliding rod is located in the piston cover and is in abutment with the second restoring member.

[0020] In one embodiment of the present application, the movable member further comprises a sealing member, which is connected to the part of the sliding rod located in the piston cover and is in abutment with the second piston, so as to block the second oil guide channel and the third chamber.

[0021] A linkage braking system, the linkage braking system comprising a front brake, a rear brake, a foot brake pump body and two brake master pumps as described above;

[0022] The second oil guide hole of one of the brake master pumps is in communication with the front brake, and the second oil guide hole of the other brake master pump is in communication with the rear brake;

[0023] The foot brake pump body is in communication with the first oil guide holes of the two brake master pumps.

[0024] The technical scheme of the present application has at least the following beneficial effects:

[0025] The brake master pump comprises a pump body, a first piston, a second piston and a piston push rod; the pump body is provided with a piston cavity, a first oil guide hole and a second oil guide hole; the first piston and the second piston are both slidably accommodated in the piston cavity along the axis of the piston cavity, and the first piston abuts against the second piston; the first piston and the second piston jointly divide the piston cavity into a first chamber, a second chamber and a third chamber; the first chamber is located at one end of the first piston away from the second piston, the second chamber is located at the outer periphery of the second piston, and the second chamber is blocked from the first chamber and the third chamber, and the third chamber is located at one end of the second piston away from the first chamber; the first oil guide hole is in communication with the second chamber, and the second oil guide hole is in communication with the third chamber; the first oil guide hole is used to be in communication with the foot brake pump body, and the second oil guide hole is used to be connected with the front brake or the rear brake; the piston push rod is connected with the pump body and in transmission connection with the first piston, and is used to drive the first piston to move under the driving action of an external force; wherein the second piston is used to move towards the direction of the second oil guide hole under the driving action of the first piston or the pressure action of the second chamber, so as to make the front brake or the rear brake brake.

[0026] Therefore, through the above structural arrangement, the brake master pump can drive the second piston to move in the piston cavity under the action of the piston push rod or the foot brake master pump, and then make the front brake or the rear brake in communication with the third chamber brake; in this way, the structure of the linkage braking system can be simplified, and the use cost of the linkage braking system can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to more clearly illustrate the technical scheme of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0028] Figure 1 The structure of the linkage braking system in the embodiments of the present application is shown in the figure;

[0029] Figure 2 Structure diagram of the brake master cylinder in the embodiment of the present application;

[0030] Figure 3 Structure diagram of the first piston and the second piston in the embodiment of the present application;

[0031] Figure 4 Structure diagram of the connection between the first piston and the second piston in the embodiment of the present application;

[0032] Figure 5 Structure diagram of the connection between the blocking member and the second piston in the embodiment of the present application.

[0033] Figure: 200-Brake linkage system; 210-Front brake; 220-Rear brake; 230-Brake pedal body; 100-Brake master cylinder; 101-First brake master cylinder; 102-Second brake master cylinder; 110-Pump body; 120-First piston; 130-Second piston; 140-Piston push rod; 111-Piston cavity; 112-First oil guide hole; 113-Second oil guide hole; 114-First cavity; 115-Second cavity; 116-Third cavity; 121-Installation slot; 150-First return member; 160-Limiting rod; 122-Strip-shaped hole; 170-Blocking member; 117-Oil pool; 123-First oil guide channel; 131-Second oil guide channel; 171-Piston cover; 172-Movable member; 173-Second return member; 174-Sliding rod; 175-Sealing member. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. The components of the embodiments of the present application described and shown in the drawings herein can be arranged and designed in various different configurations.

[0035] 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 claimed application, but merely represents selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present application.

[0036] It should be noted that: similar numbers and letters represent similar items in the following drawings, therefore, once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings.

[0037] In the description of the embodiments of the present application, it should be noted that the terms "inner", "lower", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0038] In the description of the embodiments of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms "provided", "connected" should be understood broadly, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be mechanically connected, can be directly connected, can be indirectly connected through an intermediate medium, can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0039] Please refer to Figures 1-3 The embodiment provides a linkage brake system 200, the linkage brake system 200 includes a front brake 210, a rear brake 220, a foot brake pump body 230 and two brake master pumps 100;

[0040] Both brake master pumps 100 comprise a pump body 110, a first piston 120, a second piston 130 and a piston push rod 140; the pump body 110 is provided with a piston cavity 111, a first oil guide hole 112 and a second oil guide hole 113; the first piston 120 and the second piston 130 are slidably accommodated in the piston cavity 111 along the axis of the piston cavity 111, and the first piston 120 abuts against the second piston 130; the first piston 120 and the second piston 130 jointly divide the piston cavity 111 into a first chamber 114, a second chamber 115 and a third chamber 116; the first chamber 114 is located at one end of the first piston 120 away from the second piston 130, the second chamber 115 is located at the outer periphery of the second piston 130, and the second chamber 115 is blocked from the first chamber 114 and the third chamber 116, and the third chamber 116 is located at one end of the second piston 130 away from the first chamber 114; the first oil guide hole 112 is in communication with the second chamber 115, and the second oil guide hole 113 is in communication with the third chamber 116; the first oil guide hole 112 is used to communicate with the foot brake pump body 230, and the second oil guide hole 113 is used to connect with the front brake 210 or the rear brake 220; the piston push rod 140 is connected with the pump body 110 and drivingly connected with the first piston 120, and the piston push rod 140 is used to drive the first piston 120 to move under the driving action of an external force; wherein the second piston 130 is used to move towards the direction of the second oil guide hole 113 under the driving action of the first piston 120 or the pressure action of the second chamber 115, so as to brake the front brake 210 or the rear brake 220.

[0041] The second oil guide hole 113 of one of the brake master pumps 100 is in communication with the front brake 210, and the second oil guide hole 113 of the other brake master pump 100 is in communication with the rear brake 220; the foot brake pump body 230 is in communication with the first oil guide holes 112 of the two brake master pumps 100.

[0042] It should be noted that, in the embodiment, since the linkage brake system 200 comprises two brake master pumps 100, one of the brake master pumps 100 is connected with the front brake 210 to control the braking state of the front brake 210, and the other brake master pump 100 is connected with the rear brake 220 to control the braking state of the rear brake 220, based on which, in order to distinguish the two brake master pumps 100, in the following, the brake master pump 100 connected with the front brake 210 is taken as a first brake master pump 101, and the brake master pump 100 connected with the rear brake 220 is taken as a second brake master pump 102.

[0043] Please refer to Figures 1-3 The working principle of the linkage brake system 200 is as follows:

[0044] Since the two brake master pumps 100 each include a pump body 110, a first piston 120, a second piston 130, and a piston push rod 140, and the pump body 110 is provided with a piston cavity 111, a first oil guide hole 112, and a second oil guide hole 113, the first piston 120 and the second piston 130 are slidably accommodated in the piston cavity 111 along the axis of the piston cavity 111, and the first piston 120 abuts against the second piston 130, and the two piston push rods 140 are connected with the pump body 110 and drivingly connected with the first piston 120, and the piston push rod 140 is used to drive the first piston 120 to move under the driving action of an external force; thus, when the piston push rod 140 moves relative to the pump body 110 under the action of the external force, the first piston 120 can be driven to move in the piston cavity 111 along the axis of the piston cavity 111, and since the first piston 120 abuts against the second piston 130, the movement of the first piston 120 can drive the second piston 130 to move synchronously; it should be noted that the external force acting on the piston push rod 140 is the driving force of the hand brake;

[0045] Since the first piston 120 and the second piston 130 are accommodated in the piston cavity 111, the first piston 120 and the second piston 130 also divide the piston cavity 111 into a first chamber 114, a second chamber 115, and a third chamber 116; the first chamber 114 is located at one end of the first piston 120 away from the second piston 130, the second chamber 115 is located at the outer periphery of the second piston 130, and the second chamber 115 is blocked from the first chamber 114 and the second chamber 115, and the third chamber 116 is located at one end of the second piston 130 away from the first chamber 114; the first oil guide hole 112 is in communication with the second chamber 115, the second oil guide hole 113 is in communication with the third chamber 116, the first oil guide hole 112 is used to communicate with the foot brake pump body 230, and the second oil guide hole 113 is used to be connected with the front brake 210 or the rear brake 220; thus, when the piston push rod 140 moves relative to the pump body 110 under the action of the external force, the first piston 120 can be driven to move in the piston cavity 111 along the axis of the piston cavity 111 towards the third chamber 116, thereby being able to press the hydraulic oil in the third chamber 116 into the front brake 210 or the rear brake 220, thereby making the front brake 210 or the rear brake 220 in the braking state; in addition, since the first oil guide hole 112 is in communication with the second chamber 115, and the second chamber 115 is blocked from the first chamber 114 and the second chamber 115, when the hydraulic oil in the foot brake pump body 230 is pumped into the second chamber 115, the second piston 130 can be driven to move along the axis of the piston cavity 111 towards the third chamber 116, thereby being able to press the hydraulic oil in the third chamber 116 into the front brake 210 or the rear brake 220, thereby making the front brake 210 or the rear brake 220 in the braking state; it should be noted that when the hydraulic oil in the foot brake pump body 230 is pumped into the second chamber 115, the foot brake is in the pressure state;

[0046] Therefore, the brake master cylinder 100 can adjust the working state of the front brake 210 or the rear brake 220 according to the working state of the hand brake or the foot brake, and since the linkage brake system 200 in the embodiment adopts the structure in which the second oil guide hole 113 of one brake master cylinder 100 is communicated with the front brake 210 and the second oil guide hole 113 of the other brake master cylinder 100 is communicated with the rear brake 220, and the foot brake pump body 230 is communicated with the first oil guide hole 112 of the two brake master cylinders 100, the hand brake of the front brake 210 and the rear brake 220 can independently control the first brake master cylinder 101 and the second brake master cylinder 102, so that one or both of the front brake 210 and the rear brake 220 is in the braking state, and the foot brake can also pump the hydraulic oil into the second chamber 115 of the first brake master cylinder 101 and the second brake master cylinder 102, so that the front brake 210 and the rear brake 220 are both in the braking state.

[0047] That is, the first brake master cylinder 101 and the second brake master cylinder 102 can simplify the structure of the linkage brake system 200 and reduce the use cost of the linkage brake system 200.

[0048] It should be noted that, in the linkage brake system 200, Figure 1 It can be seen that, in the linkage brake system 200, the front brake 210 and the rear brake 220 are both two, and act on the two front wheels and the two rear wheels, respectively; in addition, in the embodiment, the outer circumferential surface of the first piston 120 and the second piston 130 installed in the piston cavity 111 is provided with a sealing ring or other sealing structure.

[0049] Further, please refer to Figures 1-3 In the embodiment, in order to avoid the situation that the interval between the first piston 120 and the second piston 130 is communicated with the first chamber 114 and the second chamber 115 when the second piston 130 moves relative to the first piston 120 under the hydraulic pressure of the second chamber 115 during the movement of the first piston 120 and the second piston 130 in the piston cavity 111, the end of the first piston 120 facing the second piston 130 is provided with a mounting groove 121, and the end of the second piston 130 facing the first piston 120 is matched with the mounting groove 121. That is, through such a setting mode, when the second piston 130 moves relative to the first piston 120 under the hydraulic pressure of the second chamber 115, part of the second piston 130 remains in the matched state with the mounting groove 121, so that the second chamber 115 can be prevented from being communicated with the first chamber 114 or the third chamber 116.

[0050] In the embodiment, when the handbrake or footbrake of the linkage braking system 200 is in a static state or the external force applied to the handbrake or footbrake disappears, the first piston 120 and the second piston 130 can be restored to the original position to release the braking state of the linkage braking system 200. Therefore, in addition to the hydraulic pressure inside, the brake master cylinder 100 can further include a first restoring member 150 accommodated in the third chamber 116 and used to make the second piston 130 have a tendency to move towards the first piston 120. That is, by arranging the first restoring member 150 in the third chamber 116, when the handbrake or footbrake is in a static state or the external force applied to the handbrake or footbrake disappears, the second piston 130 can be driven to move back to the original position by applying an elastic restoring force to the second piston 130, and the first piston 120 abutting against the second piston 130 can also be driven to move back to the original position.

[0051] Please refer to Figures 1-4 In the embodiment, the first piston 120 and the second piston 130 are movably arranged in the piston chamber 111, and the second chamber 115 is in communication with the footbrake master cylinder. Therefore, in order to limit the movement stroke of the first piston 120 and avoid the movement of the first piston 120 towards the first chamber 114 when the footbrake master cylinder pumps hydraulic oil into the second chamber 115, the brake master cylinder 100 further includes a limiting rod 160 connected with the pump body 110, the first piston 120 is provided with a strip-shaped hole 122 in sliding cooperation with the limiting rod 160, and the limiting rod 160 cooperates with the strip-shaped hole 122 to limit the movement of the first piston 120. Therefore, by such an arrangement, the movement stroke of the first piston 120 can be limited, and when the footbrake master cylinder pumps hydraulic oil into the second chamber 115, the force of the hydraulic oil can act on the second piston 130 to drive the second piston 130 to move, so as to ensure that the footbrake master cylinder can drive the second piston 130 to move when working, and thus the front brake 210 and the rear brake 220 can be braked.

[0052] Further, please refer to Figures 1-5In the embodiment, the internal volume and pressure of the first chamber 114 and the second chamber 115 change during the movement of the first piston 120 and the second piston 130. In order to balance the pressure in the first chamber 114 and the third chamber 116 when the first piston 120 and the second piston 130 are stationary or return to the original position, the pump body 110 further comprises a blocking member 170. The pump body 110 further comprises an oil pool 117. The first piston 120 and the second piston 130 are respectively provided with a first oil guide channel 123 and a second oil guide channel 131. The first oil guide channel 123 and the second oil guide channel 131 are in communication. The first oil guide channel 123 is in communication with the oil pool 117, and the second oil guide channel 131 is in communication with the third chamber 116. The blocking member 170 is connected with the second piston 130, and is used to open or block the communication between the second oil guide channel 131 and the third chamber 116.

[0053] Thus, by the arrangement, when the second piston 130 moves towards the third chamber 116, the blocking member 170 blocks the second oil guide channel 131, so that the pressure in the third chamber 116 rises, and the hydraulic oil is pressed into the front brake 210 or the rear brake 220 to make them in the braking state. When the first piston 120 and the second piston 130 are stationary or return to the original position, i.e., when the second piston 130 moves towards the first chamber 114, the blocking member 170 opens the second oil guide channel 131, so that the first oil guide channel 123 and the second oil guide channel 131 are in communication, and the pressure in the first chamber 114 and the second chamber 115 returns to balance, and the second piston 130 returns to the original position under the restoring force of the first restoring member 150.

[0054] Specifically, the blocking member 170 comprises a piston cover 171, a movable member 172 and a second restoring member 173.

[0055] The piston cover 171 is accommodated in the third chamber 116 and connected with the second piston 130. The movable member 172 and the second restoring member 173 are arranged in the piston cover 171. The second restoring member 173 is used to make the movable member 172 have a tendency to block the second oil guide channel 131 towards the third chamber 116. The piston cover 171 is provided with a through hole in communication with the third chamber 116, so that the interior of the piston cover 171 is in communication with the third chamber 116.

[0056] When the second piston 130 moves towards the third chamber 116, the movable member 172 blocks the second oil guide channel 131 under the hydraulic pressure of the third chamber 116 and the action of the second restoring member 173. When the second piston 130 moves towards the first chamber 114, the second oil guide channel 131 is opened under the hydraulic pressure of the first restoring member 150 or the first chamber 114.

[0057] In the setting of the movable member 172, the movable member 172 comprises a sliding rod 174, a part of the sliding rod 174 is located in the second oil guiding channel 131 and slidably matches with the second oil guiding channel 131, the rest of the sliding rod 174 is located in the piston cover 171 and abuts against the second restoring member 173. It is to be explained that, in order to avoid that the sliding rod 174 located in the second oil guiding channel 131 blocks the second oil guiding channel 131, the part of the sliding rod 174 located in the second oil guiding channel 131 matches with the second oil guiding channel 131 in clearance.

[0058] In addition, in order to avoid the situation that the part of the sliding rod 174 contacting with the second piston 130 leaks in the blocked state, the movable member 172 further comprises a sealing member 175, the sealing member 175 is connected with the part of the sliding rod 174 located in the piston cover 171 to abut against the second piston 130, thereby blocking the second oil guiding channel 131 and the third chamber 116.

[0059] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A brake master cylinder, characterized in that: the brake master cylinder comprises a pump body, a first piston, a second piston and a piston push rod; the pump body is provided with a piston cavity, a first oil guide hole and a second oil guide hole; the first piston and the second piston are slidably accommodated in the piston cavity along the axis of the piston cavity, and the first piston and the second piston abut; the first piston and the second piston jointly divide the piston cavity into a first chamber, a second chamber and a third chamber; the first chamber is located at one end of the first piston away from the second piston, the second chamber is located at the outer periphery of the second piston, and the second chamber is blocked from the first chamber and the third chamber, and the third chamber is located at one end of the second piston away from the first chamber; the first oil guide hole is in communication with the second chamber, and the second oil guide hole is in communication with the third chamber; the first oil guide hole is used to communicate with a foot brake pump body, and the second oil guide hole is used to connect with a front brake or a rear brake; the piston push rod is connected with the pump body and drivingly connected with the first piston, and is used to drive the first piston to move under the driving action of an external force; wherein the second piston is used to move towards the direction of the second oil guide hole under the driving action of the first piston or the pressure action of the second chamber, so that the front brake or the rear brake is braked. 2.A brake master cylinder according to claim 1, characterized in that: the first piston is provided with a mounting groove at one end thereof facing the second piston, and one end of the second piston facing the first piston is matched with the mounting groove. 3.A brake master cylinder according to claim 1, characterized in that: the brake master cylinder further comprises a first restoring member, the first restoring member is accommodated in the third chamber, and is used to make the second piston have a tendency to move towards the direction of the first piston. 4.A brake master cylinder according to claim 1, characterized in that: the brake master cylinder further comprises a limiting rod, the limiting rod is connected with the pump body; the first piston is provided with a strip-shaped hole slidably matched with the limiting rod; the limiting rod and the strip-shaped hole are matched to limit the movement of the first piston. 5.A brake master cylinder according to any one of claims 1-4, characterized in that: the pump body further comprises a blocking member; the pump body further comprises an oil pool; the first piston and the second piston are respectively provided with a first oil guide channel and a second oil guide channel, the first oil guide channel and the second oil guide channel are in communication; the first oil guide channel is in communication with the oil pool, and the second oil guide channel is in communication with the third chamber; the blocking member is connected with the second piston, and is used to make the second oil guide channel in communication with or blocked from the third chamber. 6.A brake master cylinder according to claim 5, characterized in that: the blocking member comprises a piston cover, a movable member and a second restoring member. ​ ​ ​ ​ ​ ​ ​ ​ ​ The piston cover is arranged in the third chamber and connected with the second piston, and the movable element and the second restoring element are arranged in the piston cover; the second restoring element is used to make the movable element have a tendency to block the second oil guide channel at one end of the third chamber; When the second piston moves towards the third chamber, the movable element blocks the second oil guide channel under the action of the hydraulic pressure of the third chamber and the second restoring element; When the second piston moves towards the first chamber, the second oil guide channel is opened under the action of the first restoring element or the hydraulic pressure of the first chamber.

7. The brake master cylinder according to claim 6, characterized in that: The piston cover is provided with a through hole in communication with the third chamber.

8. The brake master cylinder according to claim 6, characterized in that: The movable element comprises a sliding rod, part of the sliding rod is arranged in the second oil guide channel and slidably matched with the second oil guide channel, and the rest of the sliding rod is arranged in the piston cover and abuts against the second restoring element.

9. The brake master cylinder according to claim 8, characterized in that: The movable element further comprises a sealing element connected with the part of the sliding rod arranged in the piston cover to abut against the second piston, thereby blocking the second oil guide channel and the third chamber.

10. A linkage brake system, characterized in that: The linkage brake system comprises a front brake, a rear brake, a foot brake pump body and two brake master cylinders according to any one of claims 1-9; The second oil guide hole of one of the brake master cylinders is in communication with the front brake, and the second oil guide hole of the other brake master cylinder is in communication with the rear brake; The foot brake pump body is in communication with the first oil guide holes of the two brake master cylinders.

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