Double-pull-rod center valve type hydraulic brake master cylinder

Abstract

The invention provides a double-pull-rod center valve type hydraulic brake master cylinder which comprises a cylinder body, a primary piston, a secondary piston, a center valve type device and the like. The center valve type device has the advantages that the center valve type device is high in response speed, the flow direction of brake fluid can be rapidly switched, and the instant braking requirement is met; all parts are tightly matched, stability is good, and braking force is uniform and stable; the sealing spring has small elasticity to avoid damage to the fourth sealing ring and ensure the system reliability; the spring seat and the valve seat are special in structure, so that stable work of the return spring and the pull rod and balanced circulation of brake fluid are facilitated; the connection of the primary piston and the push rod and the annular groove design of the secondary piston provide guarantee for the normal operation of the braking system. In conclusion, the patent technology effectively improves the performance and reliability of the hydraulic brake master cylinder, and provides important guarantee for safe driving of an automobile.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic brake systems, and in particular to a double-pull rod center valve type hydraulic brake master cylinder. Background Art

[0002] The hydraulic brake master cylinder is a key component in the hydraulic brake system. Here are the details about it: 1. Basic structure and composition: Cylinder: The cylinder body is the main part of the master cylinder, usually made of metal materials such as cast iron or aluminum alloy. It has good strength and sealing, and can withstand the pressure of the brake fluid. Inside the cylinder body is a smooth cylindrical cavity for accommodating the brake fluid and the movement of the piston.

[0003] piston: The piston is the part that moves in the cylinder. Its front end is usually connected to the push rod of the brake pedal. When the driver steps on the brake pedal, the push rod pushes the piston to move in the cylinder. The head of the piston has a sealing device, such as a rubber seal, to prevent brake fluid leakage. Moreover, the diameter and stroke design of the piston are determined according to the requirements of the vehicle's braking system, and the piston size of different models will be different.

[0004] Fluid reservoir: The reservoir is connected to the cylinder body and is used to store brake fluid. It usually has a transparent part to facilitate the driver to check the brake fluid level. The brake fluid in the reservoir is connected to the inside of the cylinder body through the compensation hole and the oil inlet hole. When the brake system is working, the brake fluid enters the cylinder body from the reservoir; when the brake system pressure is released, the brake fluid can flow back to the reservoir.

[0005] Oil inlet and outlet: The inlet is used to allow the brake fluid to enter the cylinder from the reservoir, while the outlet is used to transport the brake fluid in the cylinder to the brake line, and then to the brake cylinder of each wheel. The outlet is usually connected to the metal brake line and has good sealing measures to ensure that the brake fluid will not leak under high pressure.

[0006] 2. Working Principle: Braking process: When the driver steps on the brake pedal, the push rod pushes the master cylinder piston forward. The movement of the piston increases the brake fluid pressure in the cylinder. Since the fluid is almost incompressible, the pressure is quickly transmitted to the brake cylinders of each wheel through the brake pipe. In this process, the brake fluid in the master cylinder is pressed into the brake pipe through the oil outlet, and the piston in the brake cylinder pushes the brake shoe or brake caliper under the action of the hydraulic pressure, so that the wheel brake device works, thereby achieving vehicle braking.

[0007] For example, in a disc brake system, brake fluid pressure pushes a piston in the caliper, causing the caliper to clamp against the brake disc, slowing or stopping the wheel's rotation through friction.

[0008] Brake release process: When the driver releases the brake pedal, the master cylinder piston returns to its original position under the action of the return spring. At this time, the pressure in the cylinder body decreases, and the brake fluid in the brake line flows back to the master cylinder under the action of the pressure difference. At the same time, the brake fluid in the reservoir will also be replenished into the cylinder body through the compensation hole to maintain the normal fluid level and pressure balance of the brake fluid in the brake system.

[0009] refer to Figure 1 It is a traditional brake master cylinder, which has the following problems: Each time the master cylinder brakes, the master cup will pass through the oil return hole 100, which affects the service life; secondly, the compensation characteristics of the master cylinder are completed by the master cup, but the characteristic value of the master cup is difficult to control, which affects the response speed of the master cylinder, uneven braking force and other defects. Therefore, although the traditional master cylinder has a simple structure and low cost, it has certain limitations in performance and service life.

[0010] In summary, during the use of the traditional hydraulic brake master cylinder, there are defects such as easy wear of the leather cup, difficult to control the oil replenishment characteristics, slow response speed, uneven braking force, and poor stability. Summary of the invention

[0011] In view of the problems pointed out in the background technology, the present invention proposes a double-pull rod center valve type hydraulic brake master cylinder to solve the above technical problems.

[0012] The technical solution of the present invention is achieved in this way: A double-pull rod center valve type hydraulic brake master cylinder comprises a cylinder body, the cylinder body has an inner cavity with a front end opening, and a primary piston and a secondary piston are arranged in the inner cavity of the cylinder body from front to back. A first sealing ring is provided between the primary piston and the cylinder body; A second sealing ring and a third sealing ring are provided between the secondary piston and the cylinder body, the second sealing ring is located in front of the third sealing ring, a first liquid supply cavity is formed between the secondary sealing ring and the cylinder body, the first liquid supply cavity is located between the second sealing ring and the third sealing ring, a first oil return hole communicating with the first liquid supply cavity is provided on the side wall of the cylinder body, and a first oil inlet hole communicating with the first liquid supply cavity is provided on the front end surface of the secondary piston; A first brake chamber is formed between the primary piston and the secondary piston; A second brake chamber is formed between the secondary piston and the rear end of the cylinder body; A second fluid supply cavity is provided inside the side wall of the rear end of the cylinder body, a second oil return hole communicating with the second fluid supply cavity is provided on the side wall of the cylinder body, and a second oil inlet hole communicating with the second brake cavity is provided on the rear side surface of the inner cavity; A central valve device is provided between the primary piston and the secondary piston, and between the secondary piston and the rear side of the inner cavity; The central valve device comprises a spring seat and a valve seat, a return spring is arranged between the spring seat and the valve seat, the front and rear ends of the return spring are respectively against the spring seat and the valve seat, and also comprises a pull rod connecting the spring seat and the valve seat, the pull rod forms a sliding connection with the spring seat and the valve seat in the front and rear directions, the front end of the pull rod is provided with a first limiting part to prevent the pull rod from escaping from the spring seat, the rear end of the pull rod is provided with a second limiting part to prevent the pull rod from escaping from the valve seat, the rear side of the second limiting part is connected with a fourth sealing ring, a sealing spring is arranged between the second limiting part and the valve seat, and the sealing spring can apply a backward elastic force to the second limiting part; A central valve device between the primary piston and the secondary piston, wherein the spring seat is connected to the primary piston, the valve seat is connected to the secondary piston, and the first oil inlet hole can be closed when the second limiter moves backward. A first moving hole for the pull rod to move forward is provided on the rear side of the primary piston; A central valve type device is provided between the secondary piston and the rear side of the inner cavity, wherein the spring seat is abutted against the secondary piston, the valve seat is abutted against the rear side of the inner cavity, and when the second limiting portion moves backward, the second oil inlet hole can be closed. A second movable hole is provided on the rear side of the secondary piston for the pull rod to move forward.

[0013] The present invention is further configured such that the spring seat is a shell structure that is opened forward, the edge of the front end of the spring seat is provided with a first annular flange, the front end of the return spring abuts against the first flange, the rear end surface of the spring seat is provided with a first through hole that is connected to the interior thereof, the front end of the pull rod extends into the spring seat from the first through hole, the diameter of the first limiting portion is larger than the diameter of the first through hole, and the side wall of the spring seat is provided with a through hole that is connected to the inside and outside thereof.

[0014] The present invention is further configured such that the valve seat is a shell structure that is opened toward the rear, the edge of the rear end of the valve seat is provided with a second annular flange, the rear end of the return spring abuts against the second flange, the front end surface of the valve seat is provided with a second through hole that is connected to the interior thereof, the rear end of the pull rod extends into the valve seat from the second through hole, the diameter of the second limiting portion is larger than the diameter of the second through hole, and the side wall of the valve seat is provided with a through hole that connects the inside and the outside thereof.

[0015] The present invention is further configured such that the first limiting portion is slidably connected to the first movable hole.

[0016] The present invention is further configured such that the second limiting portion is slidably connected to the second movable hole.

[0017] The present invention is further configured such that a first oil outlet hole is provided on the side wall of the first brake chamber.

[0018] The present invention is further configured such that a second oil outlet hole is provided on the side wall of the second brake chamber.

[0019] The present invention is further configured such that an annular groove is provided on the outer side wall of the middle portion of the secondary piston, and the groove is the first liquid supply cavity.

[0020] The present invention is further configured such that the front end of the primary piston is connected to the push rod.

[0021] By adopting the above technical solution, the beneficial effects of the present invention are as follows: The central valve type device has a fast response speed during the braking and releasing process. Through the coordinated action of the spring seat, valve seat, pull rod, sealing spring and return spring, the oil inlet hole can be quickly closed or opened to ensure accurate switching of the flow direction of the brake fluid, thereby quickly building up or releasing the brake pressure to meet the driver's immediate needs for braking operation.

[0022] Good stability. The close fit between the components and the good performance of the seals and springs make the pressure change during braking more stable. During braking, the braking force is uniform and stable, and there will be no fluctuations, which improves driving safety and comfort.

[0023] The elastic force of the sealing spring is designed to be very small, which avoids damage to the fourth sealing ring, extends the service life of the sealing ring, and also ensures the reliability of the braking system.

[0024] The special structural design of the spring seat and valve seat, such as flanges, perforations, and side wall through holes, ensures the stable operation of the return spring and pull rod, and is also conducive to the circulation and pressure balance of the brake fluid, improving the performance of the entire brake system. The connection between the primary piston and the push rod and the design of the annular groove on the secondary piston as the first fluid supply chamber also provide strong guarantees for the normal operation of the brake system. In summary, this patented technology can effectively improve the performance and reliability of the hydraulic brake master cylinder, providing an important guarantee for the safe driving of the car. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0026] Figure 1 It is a structural schematic diagram of the prior art.

[0027] Figure 2 It is a structural schematic diagram of the present invention.

[0028] Figure 3 It is a structural schematic diagram of the central valve device of the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] For reference Figure 1-3 The present invention is described: Embodiment: A double-tie rod center valve type hydraulic brake master cylinder includes a cylinder body 1, which has an inner cavity with a front end opening, providing space for the entire brake master cylinder to install and accommodate other components. The cylinder body is usually made of high-strength metal materials, such as cast iron or aluminum alloy, to ensure that it can withstand the high pressure in the brake system.

[0031] The inner cavity of the cylinder body 1 is provided with a primary piston 2 and a secondary piston 3 from front to back, and both the primary piston 2 and the secondary piston 3 can move forward and backward, and the primary piston 2 and the secondary piston 3 form a sealing match with the side wall of the inner cavity. Both pistons can move forward and backward in the cylinder body, and form a sealing match with the side wall of the inner cavity to ensure that the brake fluid does not leak.

[0032] A first sealing ring 21 is provided between the primary piston 2 and the cylinder body 1 to form a sealing fit. The function of this sealing ring is to prevent the brake fluid from leaking between the primary piston and the cylinder body, ensuring that the pressure of the brake system can be effectively transmitted.

[0033] The second sealing ring 31 and the third sealing ring 32 form a sealing fit between the secondary piston 3 and the cylinder body 1. The second sealing ring 31 is located in front of the third sealing ring 32, and a first liquid supply chamber 33 is formed between the secondary sealing ring and the cylinder body 1. The two sealing rings work together to improve the sealing performance between the secondary piston and the cylinder body. The first liquid supply chamber 33 is located between the second sealing ring 31 and the third sealing ring 32. A first oil return hole 34 communicating with the first liquid supply chamber 33 is provided on the side wall of the cylinder body 1, and a first oil inlet hole 35 communicating with the first liquid supply chamber 33 is provided on the front end face of the secondary piston 3. During the braking process, the brake fluid can enter the first liquid supply chamber through the first oil inlet hole, and when the brake is released, the brake fluid can flow back to the reservoir through the first oil return hole.

[0034] A first brake chamber 22 is formed between the primary piston 2 and the secondary piston 3. During braking, the brake fluid pressure in this chamber increases, thereby driving other components of the brake system to work.

[0035] A second brake chamber 36 is formed between the secondary piston 3 and the rear end of the cylinder body 1. Like the first brake chamber, the second brake chamber is also filled with high-pressure brake fluid during the braking process to achieve braking of the vehicle.

[0036] A second fluid supply chamber 4 is provided inside the side wall of the rear end of the cylinder body 1, a second oil return hole 41 communicating with the second fluid supply chamber 4 is provided on the side wall of the cylinder body 1, and a second oil inlet hole 42 communicating with the second brake chamber 36 is provided on the rear side surface of the inner chamber. Similar to the first fluid supply chamber, the second fluid supply chamber also plays a role in storing and returning brake fluid in the brake system.

[0037] A central valve device is provided between the primary piston 2 and the secondary piston 3, and between the secondary piston 3 and the rear side of the inner cavity.

[0038] The central valve device includes a spring seat 5 and a valve seat 6, between which a return spring 7 is arranged, and the front and rear ends of the return spring 7 are respectively against the spring seat 5 and the valve seat 6. The function of the return spring is to push the central valve device back to the initial position when the brake is released so that the brake fluid can flow back.

[0039] It also includes a pull rod 8 connecting the spring seat 5 and the valve seat 6, which forms a sliding connection with the spring seat 5 and the valve seat 6 in the front and rear directions. The front end of the pull rod 8 is provided with a first limiting portion 81 for preventing the pull rod 8 from escaping from the spring seat 5, and the rear end of the pull rod 8 is provided with a second limiting portion 82 for preventing the pull rod 8 from escaping from the valve seat 6. The rear side of the second limiting portion 82 is connected to a fourth sealing ring 83, and a sealing spring 84 is provided between the second limiting portion 82 and the valve seat 6. The sealing spring 84 can apply a backward elastic force to the second limiting portion 82.

[0040] The central valve device between the primary piston 2 and the secondary piston 3 has a spring seat 5 that is abutted against the primary piston 2, and a valve seat 6 that is abutted against the secondary piston 3. When the second limiting portion 82 moves backward, the fourth sealing ring 83 can close the first oil inlet hole 35. The rear side surface of the primary piston 2 is provided with a first moving hole 85 for the pull rod 8 to move forward.

[0041] The central valve device between the secondary piston 3 and the rear side of the inner cavity has a spring seat 5 that is abutted against the secondary piston 3, and a valve seat 6 that is abutted against the rear side of the inner cavity. When the second limiting portion 82 moves backward, the fourth sealing ring 83 can close the second oil inlet hole 42. A second moving hole 86 is provided on the rear side of the secondary piston 3 for the pull rod 8 to move forward.

[0042] 1. Braking process: Initial state: When not braking, each component is in the initial position, the brake fluid fills the fluid supply chamber, and the pressure in the brake chamber is low.

[0043] The push rod pushes the primary piston: when the primary piston 2 moves forward under the action of the push rod 9, the primary piston begins to compress the brake fluid in the first brake chamber.

[0044] The primary piston pushes the secondary piston: At the same time, the primary piston 2 pushes the secondary piston 3 to move backward through the central valve device. In this process, the return spring 7 is compressed and deformed, and the pull rod 8 enters the corresponding first moving hole 85 or the second moving hole 86.

[0045] The central valve device closes the oil inlet hole: the pressure of the sealing spring 84 is released, acting on the pull rod 8, causing the pull rod 8 to move backward, and the fourth sealing ring 83 closes the corresponding first oil inlet hole 35 and second oil inlet hole 42. At this time, the first brake chamber 22 and the second brake chamber 36 form a closed chamber.

[0046] Building up high pressure to achieve braking: As the primary piston 2 and the secondary piston 3 continue to move backward, high pressure is built up in the first brake chamber 22 and the second brake chamber 36. Then, through the transmission of hydraulic oil, the hydraulic pressure is transmitted to each brake wheel cylinder, so that the wheels are decelerated to a stop, thus achieving the braking of the vehicle.

[0047] (II) Brake release process: Canceling the thrust: When the thrust of the push rod 9 is cancelled, the primary piston 2 and the secondary piston 3 return to their original positions and move forward under the action of the return spring 7.

[0048] The pull rod is tightened and the oil inlet hole is opened: At this time, the pull rod 8 is tightened, the sealing spring 84 is compressed, the fourth sealing ring 83 leaves the first oil inlet hole 35 and the second oil inlet hole 42, and the first oil inlet hole 35 and the second oil inlet hole 42 are opened.

[0049] Brake fluid refluxes, brake release: brake fluid refluxes to the first fluid supply chamber 33 and the second fluid supply chamber 4, and brake release occurs.

[0050] This double tie rod center valve type hydraulic brake master cylinder has the following advantages: 1. Fast response The central valve device has a fast response speed when opening or closing during the process of implementing and releasing the vehicle's brakes. This is because the sliding connection design of the pull rod, spring seat and valve seat, as well as the synergistic effect of the sealing spring and return spring, can quickly close the oil inlet hole and build up the brake pressure when the brake signal appears; when the brake release signal appears, the oil inlet hole can be quickly opened to allow the brake fluid to flow back.

[0051] (ii) Good stability Due to the close fit between the various components and the good performance of the seals and springs, the pressure changes during braking are more stable. During braking, the braking force is uniform and stable, and there will be no fluctuations, which improves driving safety and comfort.

[0052] For example, in emergency braking situations, this brake master cylinder can quickly respond to the driver's braking operation and build up sufficient braking force to stop the vehicle in the shortest possible time. In daily driving, the stability of braking can also ensure smooth deceleration of the vehicle, avoiding vehicle shaking or loss of control caused by uneven braking force.

[0053] Piston movement and spring compression: When braking begins, the primary piston 2 moves forward under the push of the push rod 9. Since the primary piston 2 and the secondary piston 3 are connected through the central valve device, the primary piston 2 will push the secondary piston 3 to move backward. In this process, the return spring 7 in the central valve device is compressed. The two ends of the return spring 7 are respectively against the spring seat 5 and the valve seat 6. As the piston moves, the spring seat 5 and the valve seat 6 approach each other, and the return spring 7 stores elastic potential energy.

[0054] Pull rod movement and oil inlet hole closing: At the same time, the pull rod 8 is slidably connected to the spring seat 5 and the valve seat 6. As the piston moves, the pull rod 8 enters the first moving hole 85 of the primary piston 2 or the second moving hole 86 of the secondary piston 3. At this time, the pressure of the sealing spring 84 is released, and a backward elastic force is applied to the second limiter 82 of the pull rod 8, so that the pull rod 8 moves backward. The fourth sealing ring 83 at the rear end of the pull rod 8 closes the corresponding first oil inlet hole 35 and the second oil inlet hole 42 during the backward movement. In this way, the first brake chamber 22 and the second brake chamber 36 form a closed cavity.

[0055] Establish high-pressure braking: After the oil inlet hole is closed, the primary piston 2 and the secondary piston 3 continue to move. Since the chamber is closed, the brake fluid cannot flow out, and the brake fluid pressure in the first brake chamber 22 and the second brake chamber 36 increases rapidly. This high-pressure brake fluid is transmitted to each brake wheel cylinder through the hydraulic system, so that the wheel brake device works and the vehicle is braked.

[0056] Piston return and tie rod tension: When braking ends and the thrust of push rod 9 is withdrawn, primary piston 2 and secondary piston 3 begin to move forward under the elastic force of return spring 7. As the piston returns, tie rod 8 is tightened, because the distance between spring seat 5 and valve seat 6 increases due to the piston return action, tie rod 8 is pulled back.

[0057] Sealing spring compression and oil inlet opening: At this time, the sealing spring 84 is compressed, and the fourth sealing ring 83 leaves the first oil inlet hole 35 and the second oil inlet hole 42 under the drive of the pull rod 8, so that the first oil inlet hole 35 and the second oil inlet hole 42 are opened.

[0058] Brake fluid reflux: The brake fluid flows back to the first fluid supply chamber 33 and the second fluid supply chamber 4 through the opened oil inlet hole, and the pressure of the entire brake system is restored to the initial state, and the brake is released. This working principle enables the central valve device to quickly and effectively control the flow of brake fluid, realize the functions of braking and brake release, and has a fast response speed and good stability in this process.

[0059] Initial state of the center valve device: In the initial state when the brake system is not working, the spring seat 5 and the valve seat 6 in the central valve device are connected by the return spring 7, and the return spring 7 is in a natural extension state or only bears a small preload to ensure the relative position stability of each component. At this time, the pull rod 8 connects the spring seat 5 and the valve seat 6 and forms a sliding connection with them in the front-to-back direction.

[0060] The first limiting portion 81 at the front end of the pull rod 8 prevents the pull rod 8 from coming out of the spring seat 5, and the second limiting portion 82 at the rear end prevents the pull rod 8 from coming out of the valve seat 6. The fourth sealing ring 83 at the rear side of the second limiting portion 82 does not block the first oil inlet hole 35 and the second oil inlet hole 42, and the oil inlet holes are in an open state, so that the brake fluid can flow normally between the corresponding chambers.

[0061] The pressure in the first brake chamber 22 and the second brake chamber 36 is in a relatively low equilibrium state, and there is no high pressure generated by the braking operation. The brake fluid can flow freely between the first fluid supply chamber 33, the second fluid supply chamber 4, the first brake chamber 22 and the second brake chamber 36, and its fluid level and pressure are maintained by the fluid reservoir of the brake system and the initial settings of the entire system.

[0062] For example, when the vehicle is parked or driving normally without braking, the distribution of brake fluid in each chamber is like an inactivated hydraulic system. The central valve device is like a "standby" device, ready to change its state according to the braking operation to control the flow direction and pressure changes of the brake fluid.

[0063] The elastic force of the sealing spring 84 is very small.

[0064] The main function of the sealing spring 84 is to assist the pull rod 8 to move backward during the braking process, so that the fourth sealing ring 83 can close the oil inlet hole in a timely and accurate manner. The design of its elastic force is very small based on many considerations. First, it can ensure that the sealing spring 84 can play a role at the appropriate time during the braking and brake release process, and will not interfere with the normal operation of other components due to excessive elastic force.

[0065] For example, during braking, when the pull rod 8 needs to move backward to close the oil inlet, a smaller elastic force can ensure that after the piston moves to a certain extent, the sealing spring 84 can smoothly push the pull rod 8 to close the oil inlet. If the elastic force is too large, the oil inlet may be closed prematurely before the piston moves fully, affecting the normal establishment of brake fluid pressure.

[0066] Since the elastic force is very small, the force applied by the sealing spring 84 to the fourth sealing ring 83 during operation is relatively mild. The fourth sealing ring 83 is a key component for sealing the oil inlet hole, and its material is usually elastic materials such as rubber. When the sealing spring 84 pushes the pull rod 8 to close the oil inlet hole, the small elastic force will not cause the fourth sealing ring 83 to be excessively squeezed or rubbed.

[0067] Taking the rubber seal ring as an example, the rubber can produce a good sealing effect when subjected to appropriate pressure, while excessive pressure will cause the rubber to deform excessively, or even crack, wear, etc. The small elastic force of the sealing spring 84 ensures that the fourth seal ring 83 works within a normal displacement range and can return to its original state after the brake is released, and will not be damaged due to frequent braking operations, thereby extending the service life of the fourth seal ring 83 and ensuring the reliability of the brake master cylinder.

[0068] The spring seat 5 is a shell structure that is open to the front. This structural form provides a space basis for the installation and matching of its internal components. The edge of the front end of the spring seat 5 is provided with a first annular flange 51. The front end of the return spring 7 is against the first flange 51. The existence of the first flange 51 provides a stable point of force for the return spring 7. The rear end surface of the spring seat 5 is provided with a first through hole 52 that is connected to the inside. The front end of the pull rod 8 extends into the spring seat 5 from the first through hole 52. The diameter of the first limiting portion 81 is larger than the diameter of the first through hole 52. This design cleverly limits the possibility of the pull rod 8 escaping from the spring seat 5 forward, and plays a limiting role. The side wall of the spring seat 5 is provided with a through hole that connects the inside and outside. The through hole allows the brake fluid to circulate inside and outside the spring seat 5, ensuring that the brake fluid can better balance the pressure and distribute the flow between different chambers in the entire brake master cylinder, which helps to achieve a more stable and efficient braking process.

[0069] The valve seat 6 is a shell structure that opens toward the rear. The edge of the rear end of the valve seat 6 is provided with a second annular flange 61. The rear end of the return spring 7 abuts against the second flange 61. The second flange 61 plays a key supporting role. It cooperates with the first flange 51 at the front end of the spring seat 5 to stably limit the return spring 7 between the two. Whether the return spring 7 is compressed during the braking process or the return spring 7 rebounds and resets after the brake is released, the second flange 61 can provide a solid point of force for the rear end of the return spring 7, ensuring that the return spring 7 is evenly stressed and stable in the axial direction, thereby ensuring that the entire central valve device can operate accurately according to the established workflow, which plays an indispensable role in maintaining the normal performance of the braking system. The front end surface of the valve seat 6 is provided with a second through hole 62 that is connected to the interior thereof. The rear end of the pull rod 8 extends into the valve seat 6 from the second through hole 62. The diameter of the second limiting portion 82 is larger than the diameter of the second through hole 62. Such a design structure effectively prevents the pull rod 8 from falling out of the valve seat 6 backwards, and realizes the limiting function of the rear end of the pull rod 8. A through hole connecting the inside and outside of the valve seat 6 is provided on the side wall thereof, and the through hole enables the brake fluid to flow inside and outside the valve seat 6, thereby helping to achieve reasonable distribution and pressure balance of the brake fluid among different chambers of the entire brake master cylinder.

[0070] The first limit portion 81 is slidably connected to the first moving hole 85. This design is to allow the pull rod 8 to move axially relative to the primary piston 2 flexibly and stably during the operation of the brake system. The size and shape of the first limit portion 81 are adapted to the first moving hole 85, so that the pull rod 8 can slide back and forth smoothly in the hole, and can ensure that there is no excessive shaking or separation during the sliding process. For example, the first limit portion 81 may be a disc-shaped structure with a suitable diameter, and the first moving hole 85 is a matching circular hole, and a small gap is maintained between the two to achieve a good sliding fit effect.

[0071] Similarly, the second stopper 82 is slidably connected to the second moving hole 86. The size and shape of the second stopper 82 are carefully designed to fit closely with the second moving hole 86, and an appropriate gap is maintained between the two to ensure that the rear end of the pull rod 8 can slide smoothly back and forth in the second moving hole 86 of the secondary piston 3. For example, the second stopper 82 may be a flange-like structure, and the second moving hole 86 is a hole shape corresponding thereto, and such a design makes the sliding between them both flexible and reliable.

[0072] A first oil outlet hole 221 is provided on the side wall of the first brake chamber 22. It is an opening structure directly connected to the internal space of the first brake chamber 22. The size of the hole is carefully designed to ensure that the brake fluid can smoothly flow through it to the subsequent brake pipeline during the braking process, and to maintain good sealing in the non-braking state to prevent brake fluid leakage. The position of this oil outlet hole is usually determined according to the layout of the entire brake master cylinder in the vehicle braking system and the optimal path of hydraulic transmission, so as to efficiently transmit the hydraulic pressure generated in the first brake chamber 22.

[0073] A second oil outlet hole 361 is provided on the side wall of the second brake chamber 36. It is also a key structure that is directly connected to the inside of the second brake chamber 36. It is similar to the first oil outlet hole 221, has an adapted aperture, and has high machining accuracy and sealing requirements to ensure that it can function accurately under different working conditions. Its specific position on the side wall also comprehensively considers the hydraulic conduction path of the entire brake system and the overall layout requirements of the vehicle brake, aiming to achieve that the brake fluid can efficiently and accurately flow out of the second brake chamber 36 and be transferred to the corresponding braking part.

[0074] An annular groove 331 is provided on the outer wall of the middle part of the secondary piston 3, and this groove is defined as the first fluid supply chamber 33. It presents an annular shape surrounding the secondary piston 3, and its depth and width and other dimensions are determined according to the overall design requirements of the brake master cylinder and the parameters such as the flow rate and pressure of the brake fluid. The inner and outer walls of the groove have high processing accuracy to ensure a good fit with the piston body and the side wall of the cylinder body 1, which can not only ensure the normal storage and flow of the brake fluid therein, but also maintain reliable sealing performance to prevent the brake fluid from leaking to other areas where it should not appear.

[0075] The front end of the primary piston 2 is connected to the push rod 9 .

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A double-tie rod center valve type hydraulic brake master cylinder, comprising a cylinder body (1), the cylinder body (1) having an inner cavity with a front end opening, a primary piston (2) and a secondary piston (3) being arranged in sequence from front to back in the inner cavity of the cylinder body (1), characterized in that: A first sealing ring (21) is provided between the primary piston (2) and the cylinder body (1); A second sealing ring (31) and a third sealing ring (32) are provided between the secondary piston (3) and the cylinder body (1), the second sealing ring (31) being located in front of the third sealing ring (32), a first liquid supply chamber (33) being formed between the secondary sealing ring and the cylinder body (1), the first liquid supply chamber (33) being located between the second sealing ring (31) and the third sealing ring (32), a first oil return hole (34) communicating with the first liquid supply chamber (33) being provided on the side wall of the cylinder body (1), and a first oil inlet hole (35) communicating with the first liquid supply chamber (33) being provided on the front end surface of the secondary piston (3); A first brake chamber (22) is formed between the primary piston (2) and the secondary piston (3); A second brake chamber (36) is formed between the secondary piston (3) and the rear end of the cylinder body (1); A second liquid supply chamber (4) is provided inside the side wall at the rear end of the cylinder body (1), a second oil return hole (41) communicating with the second liquid supply chamber (4) is provided on the side wall of the cylinder body (1), and a second oil inlet hole (42) communicating with the second brake chamber (36) is provided on the rear side surface of the inner chamber; A central valve device is provided between the primary piston (2) and the secondary piston (3), and between the secondary piston (3) and the rear side of the inner cavity; The central valve device comprises a spring seat (5) and a valve seat (6), a return spring (7) is provided between the spring seat (5) and the valve seat (6), the front and rear ends of the return spring (7) are respectively against the spring seat (5) and the valve seat (6), and also comprises a pull rod (8) connecting the spring seat (5) and the valve seat (6), the pull rod (8) forms a sliding connection with the spring seat (5) and the valve seat (6) in the front and rear directions, the front end of the pull rod (8) is provided with a first limiting portion (81) for preventing the pull rod (8) from escaping from the spring seat (5), the rear end of the pull rod (8) is provided with a second limiting portion (82) for preventing the pull rod (8) from escaping from the valve seat (6), the rear side of the second limiting portion (82) is connected with a fourth sealing ring (83), a sealing spring (84) is provided between the second limiting portion (82) and the valve seat (6), and the sealing spring (84) can apply a backward elastic force to the second limiting portion (82); A central valve device between the primary piston (2) and the secondary piston (3), wherein the spring seat (5) is in contact with the primary piston (2), the valve seat (6) is in contact with the secondary piston (3), and when the second limiting portion (82) moves backward, the fourth sealing ring (83) can close the first oil inlet hole (35), and a first moving hole (85) for the pull rod (8) to move forward is provided on the rear side surface of the primary piston (2); A central valve device is provided between the secondary piston (3) and the rear side surface of the inner cavity, wherein the spring seat (5) is abutted against the secondary piston (3), the valve seat (6) is abutted against the rear side surface of the inner cavity, and when the second limiting portion (82) moves backward, the fourth sealing ring (83) can close the second oil inlet hole (42), and a second moving hole (86) is provided on the rear side surface of the secondary piston (3) for the pull rod (8) to move forward.

2. A double-tie-rod center-valve hydraulic brake master cylinder according to claim 1, characterized in that: The spring seat (5) is a shell structure that is opened forward. The edge of the front end of the spring seat (5) is provided with a first annular flange (51). The front end of the return spring (7) abuts against the first flange (51). The rear end surface of the spring seat (5) is provided with a first through hole (52) that is connected to the interior of the spring seat. The front end of the pull rod (8) extends into the spring seat (5) through the first through hole (52). The diameter of the first limiting portion (81) is larger than the diameter of the first through hole (52). The side wall of the spring seat (5) is provided with a through hole that connects the inside and the outside.

3. The double-tie-rod center-valve hydraulic brake master cylinder according to claim 1, characterized in that: The valve seat (6) is a shell structure that is opened toward the rear. The edge of the rear end of the valve seat (6) is provided with an annular second flange (61). The rear end of the return spring (7) abuts against the second flange (61). The front end surface of the valve seat (6) is provided with a second through hole (62) that is connected to the interior thereof. The rear end of the pull rod (8) extends into the valve seat (6) from the second through hole (62). The diameter of the second limiting portion (82) is larger than the diameter of the second through hole (62). The side wall of the valve seat (6) is provided with a through hole that connects the inside and the outside thereof.

4. The double-tie-rod center-valve hydraulic brake master cylinder according to claim 1, characterized in that: The first limiting portion (81) is slidably connected to the first moving hole (85).

5. The double-tie-rod center-valve hydraulic brake master cylinder according to claim 1, characterized in that: The second limiting portion (82) is slidably connected to the second movable hole (86).

6. The double-tie-rod center-valve hydraulic brake master cylinder according to claim 1, characterized in that: A first oil outlet hole (221) is provided on the side wall of the first brake chamber (22).

7. The double-tie-rod center-valve hydraulic brake master cylinder according to claim 1, characterized in that: A second oil outlet hole (361) is provided on the side wall of the second brake chamber (36).

8. The double-tie-rod center-valve hydraulic brake master cylinder according to claim 1, characterized in that: An annular groove (331) is provided on the outer side wall of the middle portion of the secondary piston (3), and the groove (331) is the first liquid supply chamber (33).

9. The double-tie-rod center-valve hydraulic brake master cylinder according to claim 1, characterized in that: The front end of the primary piston (2) is connected to the push rod (9).

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