A car brake master cylinder

Abstract

The present invention provides a master brake cylinder for an automobile, belonging to the field of automobile brake technology, and solves the problem of the prior art master brake cylinder being a split assembly and having poor stability. The present invention comprises a pump body, wherein a movable first piston and a rear axle brake unit arranged below the first piston and capable of controlling the braking of the rear axle of the automobile are provided within the pump body, a force-applying member for pushing the first piston is provided above the first piston, a second piston is provided below the rear axle brake unit, a front axle brake unit for controlling the braking of the front axle of the automobile is provided below the second piston, the first piston can open or close the rear axle brake unit, and the second piston can open or close the front axle brake unit, the pump body is an integrated type, a chassis is integrally formed within the pump body, an assembly body that can be attached to the inner wall of the pump body is provided above the chassis, the first piston and the rear axle brake unit are arranged within the assembly body, and a positioning mechanism is provided on the pump body that can assemble and position the assembly body along the axial direction of the pump body.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile brakes, and in particular relates to an automobile brake master cylinder. Background Art

[0002] In the automobile braking system, the master brake cylinder controls the opening and closing of the air relay valve by controlling the output of compressed gas, thereby controlling the brake cylinder and ultimately controlling the braking action to achieve braking of the vehicle.

[0003] Existing automotive brake master cylinders vary in structure, but all operate on roughly the same principle. They typically ventilate a compressible chamber through an air inlet. The user then steps on a force-applying element, which pushes a piston to compress the chamber. The gas in the chamber then flows to an outlet, thereby controlling a relay valve.

[0004] The master brake cylinder in the existing technology is a split structure, in which the front brake part and the rear brake part are manufactured separately and then assembled together. Therefore, there will inevitably be a small gap at the junction of the two parts. Although this structure can ensure a certain tightness when assembled, after a certain period of use, the gap will increase, which may easily cause some parts in the pump body to be misaligned and skewed, ultimately affecting the braking effect. Summary of the Invention

[0005] The purpose of the present invention is to address the above-mentioned problems existing in the prior art and to propose an integrated automobile brake master cylinder.

[0006] The objectives of the present invention can be achieved through the following technical solutions: A car brake master cylinder, comprising a pump body, wherein the pump body is provided with a movable first piston and a rear axle brake unit arranged below the first piston and capable of controlling the braking of the rear axle of the car, a force-applying member is provided above the first piston and capable of pushing the movable piston, a second piston is provided below the rear axle brake unit, a front axle brake unit capable of controlling the braking of the front axle of the car is provided below the second piston, the first piston can open or close the rear axle brake unit, the second piston can open or close the front axle brake unit, the pump body is one-piece, a chassis is integrally formed within the pump body, an assembly body which can be attached to the inner wall of the pump body is provided above the chassis, the first piston and the rear axle brake unit are arranged within the assembly body, and a positioning mechanism is provided on the pump body which can assemble and position the assembly body along the axial direction of the pump body.

[0007] By designing an integrally formed pump body and chassis and installing an assembly on the chassis, the rear axle brake and the front axle brake are integrated, eliminating the need for splicing and assembling the pump body. Consequently, no assembly gap is created, ensuring a good braking effect even after long-term use. The first piston and the rear axle brake unit are disposed within the assembly, optimizing the internal structure of the pump body. A positioning mechanism is provided on the pump body to position the assembly, ensuring the stability of the assembly and the internal structure of the pump body.

[0008] In the above-mentioned automobile brake master cylinder, the positioning mechanism includes a positioning piece arranged on the assembly and a positioning column arranged on the pump body. The bottom of the positioning piece is tightly attached to the top of the assembly, and the positioning column passes through the pump body and is connected to the positioning piece.

[0009] A positioning piece is provided on the top of the assembly to limit its axial movement along the pump body, and a positioning column is used to fix the positioning piece from one side of the pump body.

[0010] In the above-mentioned automobile brake master cylinder, the positioning member is provided with a limiting portion, the force applying member is provided with a first step, the limiting portion abuts against the first step, and the limiting portion can be pressed against the first step to axially limit the force applying member.

[0011] In the above-mentioned automobile brake master cylinder, the pump body is provided with a limiting structure that can limit the movement of the positioning member along the axial direction of the pump body. By providing the limiting structure to limit the movement of the positioning member, the positioning accuracy of the positioning mechanism is ensured.

[0012] In the aforementioned automotive brake master cylinder, the limiting structure includes a snap-fit ​​groove provided on the pump body and a snap ring provided above the positioning member. The snap ring engages with the snap-fit ​​groove and abuts against the positioning member. The snap ring limits axial movement of the positioning member along the pump body, and the snap-fit ​​groove is configured to engage with the snap ring.

[0013] In the above-mentioned automobile brake master cylinder, the positioning column and the assembly body are detachably connected. By arranging the positioning column and the assembly body in a detachable connection, it is convenient to inspect and replace parts.

[0014] In the above-mentioned automobile brake master cylinder, the second piston is provided with a push rod which can be pushed by the first piston, and the pump body is provided with a first adjustment structure which can adjust the distance between the push rod and the first piston.

[0015] The first adjustment structure is used to adjust the distance between the push rod and the first piston. By changing the distance between the two, the air pressure between the two is changed, thereby adjusting the air pressure difference between the rear axle brake mechanism and the front axle brake mechanism. The sensitivity of the emergency brake can also be adjusted to achieve different braking effects.

[0016] In the above-mentioned automobile brake master cylinder, the first adjustment structure includes a first internal thread arranged on the second piston, a first external thread arranged on the outside of the push rod and matching the first internal thread, and a first force-bearing part arranged on the push rod. The first force-bearing part can be subjected to force to drive the push rod to rotate.

[0017] The second piston is threadedly connected to the push rod by arranging the first internal thread and the first external thread, and the distance between the two can be adjusted by rotation. The first force-bearing part can drive the push rod to rotate under the force of the adjustment tool.

[0018] In the above-mentioned automobile brake master cylinder, a first return spring capable of returning the force applying member to its original position and a second adjustment structure capable of adjusting the deformation degree of the first return spring are provided between the force applying member and the first piston.

[0019] After the user releases the force on the force applying member, the force applying member is reset by the elastic action of the first reset spring. The second adjustment structure can be used to adjust the deformation degree of the first reset spring, that is, to adjust the sensitivity of the force applying member.

[0020] In the above-mentioned automobile brake master cylinder, the second adjustment structure includes an adjusting rod arranged between the first piston and the force-applying member, a second internal thread arranged on the force-applying member, a second external thread arranged on the adjusting rod and matching the second internal thread, and a second force-bearing part arranged on the adjusting rod. The second force-bearing part can be forced to drive the adjusting rod to rotate, a spring seat is provided under the first return spring, and a second step is provided on the adjusting rod that can be against the spring seat.

[0021] By arranging the second internal thread and the second external thread, the adjusting rod is threadedly connected to the force applying member, and the spring seat and the step are abutted against each other, so that the adjusting rod applies force to the spring seat, and the spring seat then applies force to the spring.

[0022] In the aforementioned automotive brake master cylinder, a through hole is provided at the bottom of the pump body for inserting an adjustment tool into the pump body. The through hole facilitates inserting the adjustment tool into the pump body to adjust the distance between the push rod and the first piston in conjunction with the first adjustment structure.

[0023] Compared with the prior art, the present invention integrates the rear axle brake and the front axle brake by designing an integrally formed pump body and chassis and installing an assembly on the chassis. There is no need to splice and assemble the pump body, so no assembly gap is generated, ensuring that the braking effect is still good after long-term use; the first piston and the rear axle brake unit are arranged in the assembly, the internal structure of the pump body is optimized, and the assembly is positioned by arranging a positioning mechanism on the pump body to ensure the stability of the assembly and the internal structure of the pump body; the movement of the positioning part is limited by arranging a limit structure to ensure the positioning accuracy of the positioning mechanism; the positioning column and the assembly are arranged to be detachably connected to facilitate maintenance and replacement of parts; the first adjustment structure is arranged to adjust the sensitivity of the emergency brake to achieve different braking effects; the second adjustment structure is arranged to adjust the sensitivity of the force-applying member, and the user can choose the appropriate force to apply force to the force-applying member. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0025] Figure 2 It is a three-dimensional schematic diagram of the present invention after hiding part of the structure;

[0026] Figure 3 It is a cross-sectional structural diagram of the present invention;

[0027] Figure 4 1 is a schematic diagram of the three-dimensional structure of the push rod of the present invention;

[0028] Figure 5 It is a schematic diagram of the three-dimensional structure of the adjusting rod of the present invention;

[0029] In the figure, 1, pump body; 2, force member; 21, first step; 3, first piston; 4, rear axle brake unit; 41, first valve; 42, first cavity; 43, second cavity; 44, first air inlet; 45, first air outlet; 46, first valve disc; 5, second piston; 6, front axle brake unit; 61, second valve; 62, third cavity; 63, fourth cavity; 64, second air inlet; 65, second air outlet; 66, second valve disc; 7, chassis; 8, assembly; 9, positioning mechanism; 91, positioning member; 911, limiter; 92, fixed Positioning column; 10. Limiting structure; 101. Clamping groove; 102. Snap ring; 11. Push rod; 12. First adjusting structure; 121. First internal thread; 122. First external thread; 123. First force-bearing part; 13. Second adjusting structure; 131. Adjusting rod; 132. Second internal thread; 133. Second external thread; 134. Second force-bearing part; 135. Second step; 14. First return spring; 15. Spring seat; 16. Through hole; 17. Second return spring; 18. Third return spring; 19. Fourth return spring; 20. Fifth return spring. DETAILED DESCRIPTION

[0030] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0031] like Figure 1-5 As shown, the present invention includes a pump body 1, wherein a movable first piston 3 and a rear axle brake unit 4 arranged below the first piston 3 and capable of controlling the rear axle brake of the automobile are provided in the pump body 1, a force-applying member 2 capable of pushing the movable first piston 3 is provided above the first piston 3, a second piston 5 is provided below the rear axle brake unit 4, a front axle brake unit 6 capable of controlling the front axle brake of the automobile is provided below the second piston 5, the first piston 3 can open or close the rear axle brake unit 4, the second piston 5 can open or close the front axle brake unit 6, the pump body 1 is an integrated type, a chassis 7 is integrally formed in the pump body 1, an assembly 8 capable of being attached to the inner wall of the pump body 1 is provided above the chassis 7, the first piston 3 and the rear axle brake unit 4 are arranged in the assembly 8, and a positioning mechanism 9 is provided on the pump body 1 for assembling and positioning the assembly 8 along the axial direction of the pump body 1.

[0032] The rear axle brake unit 4 includes a first valve 41 disposed below the first piston 3, a first chamber 42 disposed between the first piston 3 and the first valve 41, a second chamber 43 disposed within the first valve 41, a first air inlet 44 for admitting gas, and a first air outlet 45 for exhausting gas, disposed on the pump body 1. The first air inlet 44 communicates with the second chamber 43, and the first chamber 42 communicates with the second chamber 43 and the first air outlet 45, respectively. Gas within the first chamber 42 can be squeezed into the first air outlet 45 by the first piston 3. The first air inlet 44 maintains intake and passes gas into the second chamber 43. Gas passes from the second chamber 43 into the first chamber 42. The downward movement of the first piston 3 squeezes the gas within the first chamber 42 into the first air outlet 45. The first air outlet 45 can be connected to a relay valve to control rear axle braking. The first valve 41 is provided with a first valve flap 46 that can be opened by the first piston 3. The first valve flap 46 is provided with a first vent hole (not shown in the figure). A third return spring 18 is provided below the first valve flap 46 to reset it. During normal braking, gas in the second chamber 43 enters the first chamber 42 through the first vent hole. During emergency braking, the first piston 3 can overcome the elastic force of the second return spring 17 to push open the first valve flap 46. Gas in the second chamber 43 can quickly enter the first chamber 42 through the gap between the first valve 41 and the first valve flap 46, and then flow from the first chamber 42 to the first air outlet 45. A second return spring 17 is provided below the first piston 3 to reset it.

[0033] The front axle braking mechanism includes a second valve 61 disposed below the second piston 5, a third chamber 62 disposed between the second piston 5 and the second valve 61, a fourth chamber 63 disposed within the second valve 61, a second air inlet 64 disposed on the pump body 1 for admitting gas, and a second air outlet 65 for discharging gas. The second air inlet 64 communicates with the fourth chamber 63, and the third chamber 62 communicates with the fourth chamber 63 and the second air outlet 65, respectively. The gas within the third chamber 62 can be squeezed to the second air outlet 65 by the second piston 5. The second air inlet 64 maintains intake and passes the gas into the fourth chamber 63, and the gas passes from the fourth chamber 63 into the third chamber 62. The downward movement of the second piston 5 can squeeze the gas within the third chamber 62 to the second air outlet 65. The second air outlet 65 can be connected to a relay valve to control the front axle braking. The second valve 61 is provided with a second valve flap 66 that can be opened by the second piston 5. The second valve flap 66 is provided with a second vent hole (not shown in the figure). A fourth return spring 19 is provided below the second valve flap 66 to reset it. During normal braking, gas in the fourth chamber 63 enters the third chamber 62 through the second vent hole. During emergency braking, the second piston 5 can overcome the elastic force of the third return spring 18 to push open the second valve flap 66. Gas in the fourth chamber 63 can quickly enter the third chamber 62 through the gap between the second valve 61 and the second valve flap 66, and then flow from the third chamber 62 to the second air outlet 65. The second piston 5 is disposed between the chassis 7 and the assembly 8. A fifth return spring 20 is provided between the chassis 7 and the second piston 5 to reset the second piston 5.

[0034] By designing an integrally formed pump body 1 and chassis 7 and installing an assembly 8 on the chassis 7, the rear axle brake and the front axle brake are integrated, and there is no need to splice and assemble the pump body 1, so no assembly gap is generated, ensuring that the braking effect is still good after long-term use; the first piston 3 and the rear axle brake unit 4 are arranged in the assembly 8, the internal structure of the pump body 1 is optimized, and the assembly 8 is positioned by arranging a positioning mechanism 9 on the pump body 1 to ensure the stability of the assembly 8 and the internal structure of the pump body 1.

[0035] The positioning mechanism 9 includes a positioning member 91 provided on the assembly 8 and a positioning column 92 provided on the pump body 1. The bottom of the positioning member 91 is in close contact with the top of the assembly 8, and the positioning column 92 passes through the pump body 1 and is connected to the positioning member 91. By providing the positioning member 91 on the top of the assembly 8, its axial movement along the pump body 1 is limited, and the positioning column 92 is used to fix the positioning member 91 from one side of the pump body 1. A limiting portion 911 is provided on the positioning member 91, and a first step 21 is provided on the force-applying member 2. The limiting portion 911 is against the first step 21. The limiting portion 911 can be pressed against the first step 21 to limit the axial position of the force-applying member 2.

[0036] The pump body 1 is provided with a limiting structure 10 that can limit the axial movement of the positioning member 91 along the pump body 1. By providing the limiting structure 10 to limit the movement of the positioning member 91, the positioning accuracy of the positioning mechanism 9 is ensured. The limiting structure 10 includes a snap-fit ​​groove 101 provided on the pump body 1 and a snap ring 102 provided above the positioning member 91. The snap ring 102 snaps into the snap-fit ​​groove 101 and abuts against the positioning member 91. The snap ring 102 can limit the axial movement of the positioning member 91 along the pump body 1, and the snap-fit ​​groove 101 is used to snap into the snap ring 102.

[0037] The positioning post 92 is detachably connected to the assembly 8. By arranging the positioning post 92 and the assembly 8 to be detachably connected, it is convenient to overhaul and replace parts.

[0038] The second piston 5 is provided with a push rod 11 that can be pushed by the first piston 3. The pump body 1 is provided with a first adjustment structure 12 that can adjust the distance between the push rod 11 and the first piston 3. The first adjustment structure 12 is used to adjust the distance between the push rod 11 and the first piston 3. By changing the distance between the push rod 11 and the first piston 3, the air pressure between the push rod 11 and the first piston 3 is changed. This adjusts the air pressure difference between the rear axle brake mechanism and the front axle brake mechanism, and also adjusts the sensitivity of the emergency brake, thereby achieving different braking effects.

[0039] The first adjustment structure 12 includes a first internal thread 121 provided on the second piston 5, a first external thread 122 provided on the outside of the push rod 11 and matching the first internal thread 121, and a first force-bearing portion 123 provided on the push rod 11. The first force-bearing portion 123 is capable of receiving force to drive the push rod 11 to rotate. By providing the first internal thread 121 and the first external thread 122, the second piston 5 and the push rod 11 are threadedly connected, and the distance between them can be adjusted by rotation. The first force-bearing portion 123 can drive the push rod 11 to rotate under the force of the adjustment tool.

[0040] A first return spring 14 for returning the force-applying member 2 to its original position and a second adjustment structure 13 for adjusting the deformation of the first return spring 14 are provided between the force-applying member 2 and the first piston 3. After the user releases force from the force-applying member 2, the force-applying member 2 is resiliently returned to its original position by the elastic action of the first return spring 14. The second adjustment structure 13 is used to adjust the deformation of the first return spring 14, thereby adjusting the sensitivity of the force-applying member 2.

[0041] The second adjustment structure 13 includes an adjustment rod 131 disposed between the first piston 3 and the force-applying member 2, a second internal thread 132 disposed on the force-applying member 2, a second external thread 133 disposed on the adjustment rod 131 and matching the second internal thread 132, and a second force-bearing portion 134 disposed on the adjustment rod 131. The second force-bearing portion 134 can be forced to drive the adjustment rod 131 to rotate. A spring seat 15 is disposed below the first return spring 14, and a second step 135 is disposed on the adjustment rod 131, which can abut against the spring seat 15. The second internal thread 132 and the second external thread 133 enable the adjustment rod 131 to be threadedly connected to the force-applying member 2, abutting the spring seat 15 against the step, facilitating the adjustment rod 131 to apply force to the spring seat 15, which in turn applies force to the spring.

[0042] The bottom of the pump body 1 is provided with a through hole 16 for an adjusting tool to be inserted into the pump body 1. By providing the through hole 16 at the bottom of the pump body 1, it is convenient to insert the adjusting tool into the pump body 1 to cooperate with the first adjusting structure 12 to adjust the distance between the push rod 11 and the first piston 3.

[0043] The working principle of the present invention is as follows: in the working state, the first air inlet 44 and the second air inlet 64 continuously take in air, and the gas in the first air inlet 44 passes through the second cavity 43 and then passes through the first vent hole on the first valve disc 46 to enter the first cavity 42. When braking slowly, that is, slowly stepping on the force member 2, the force member 2 pushes the first piston 3 to move downward to squeeze the first cavity 42, and the gas in the first cavity 42 is squeezed to the first air outlet 45. The first air outlet 45 is connected to the relay valve to control the braking of the rear axle. The gas in the second air inlet 64 passes through the fourth cavity 63 and then passes through the second vent hole on the second valve disc 66 to enter the third cavity 62. Since the first cavity 42 is squeezed, part of the gas pushes the second piston 5 downward through the push rod 11, and the second piston 5 squeezes the third cavity 62 downward. The gas in the third cavity 62 is squeezed to the second air outlet 65, which is also connected to the relay valve. To control the braking of the front axle, when braking suddenly, that is, stepping on the force-applying member 2 quickly, the force-applying member 2 quickly pushes the first piston 3 downward, and the first piston 3 can quickly press the first valve flap 46 below and open it. The gas in the second chamber 43 can quickly enter the first chamber 42 and be squeezed to the first air outlet 45 by the first piston 3, thereby realizing rapid braking of the rear axle. At the same time, the first piston 3 will also press the push rod 11, driving the push rod 11 to move downward quickly. The downward movement of the push rod 11 drives the second piston 5 to press downward and open the second valve flap 66, and the gas in the fourth chamber 63 can quickly enter the third chamber 62 and be squeezed to the second air outlet 65 by the second piston 5, thereby realizing rapid braking of the front axle. In actual application, the axial position of the push rod 11 and the adjusting rod 131 can be adjusted by using an adjusting tool to extend into the through hole 16 at the bottom of the pump body 1 as needed, so as to change the sensitivity of the force applied by stepping on the force-applying member 2 and the sensitivity of sudden braking.

[0044] The present invention integrates the rear axle brake and the front axle brake by designing an integrally formed pump body 1 and chassis 7, and installing an assembly body 8 on the chassis 7. There is no need to splice and assemble the pump body 1, so no assembly gap is generated, ensuring that the braking effect is still good after long-term use; the first piston 3 and the rear axle brake unit 4 are arranged in the assembly body 8, the internal structure of the pump body 1 is optimized, and the assembly body 8 is positioned by arranging a positioning mechanism 9 on the pump body 1 to ensure the stability of the assembly body 8 and the internal structure of the pump body 1; the movement of the positioning member 91 is limited by arranging a limiting structure 10 to ensure the positioning accuracy of the positioning mechanism 9; the positioning column 92 and the assembly body 8 are arranged to be detachably connected, which is convenient for maintenance and replacement of parts; the first adjustment structure 12 is provided to adjust the sensitivity of the emergency brake to achieve different braking effects; the second adjustment structure 13 is provided to adjust the sensitivity of the force member 2, and the user can choose the appropriate force to apply force to the force member 2.

[0045] The specific embodiments described herein are merely illustrative of the spirit of the present invention. Persons skilled in the art may make various modifications, additions, or substitutions to the described specific embodiments without departing from the spirit of the present invention or exceeding the scope of the appended claims.

Claims

1. A car brake master cylinder, characterized in that: The invention comprises a pump body (1), wherein a movable first piston (3) is provided in the pump body (1), and a rear axle brake unit (4) is provided below the first piston (3) and can control the braking of the rear axle of the automobile. A force-applying member (2) is provided above the first piston (3) and can push the movable rear axle brake unit. A second piston (5) is provided below the rear axle brake unit (4), and a front axle brake unit (6) is provided below the second piston (5) and can control the braking of the front axle of the automobile. The first piston (3) can open or close the rear axle brake. The pump body (1) is an integrated pump body, a chassis (7) is formed integrally in the pump body (1), an assembly body (8) is provided above the chassis (7) and can be attached to the inner wall of the pump body (1), the first piston (3) and the rear axle brake unit (4) are arranged in the assembly body (8), and a positioning mechanism (9) is provided on the pump body (1) for assembling and positioning the assembly body (8) along the axial direction of the pump body (1); A first return spring (14) capable of returning the force-applying member (2) and a second adjustment structure (13) capable of adjusting the deformation degree of the first return spring (14) are provided between the force-applying member (2) and the first piston (3); The second adjustment structure (13) includes an adjustment rod (131) arranged between the first piston (3) and the force-applying member (2), a second internal thread (132) arranged on the force-applying member (2), a second external thread (133) arranged on the adjustment rod (131) and matching the second internal thread (132), and a second force-bearing portion (134) arranged on the adjustment rod (131). The second force-bearing portion (134) can be forced to drive the adjustment rod (131) to rotate. A spring seat (15) is provided below the first return spring (14), and a second step (135) is provided on the adjustment rod (131) that can abut against the spring seat (15).

2. The automobile brake master cylinder according to claim 1, characterized in that: The positioning mechanism (9) includes a positioning member (91) provided on the assembly (8) and a positioning column (92) provided on the pump body (1). The bottom of the positioning member (91) is in close contact with the top of the assembly (8), and the positioning column (92) passes through the pump body (1) and is connected to the positioning member (91).

3. The automobile brake master cylinder according to claim 2, characterized in that: The positioning member (91) is provided with a limiting portion (911), the force applying member (2) is provided with a first step (21), and the limiting portion (911) abuts against the first step (21).

4. The automobile brake master cylinder according to claim 2 or 3, characterized in that: The pump body (1) is provided with a limiting structure (10) capable of limiting the axial movement of the positioning member (91) along the pump body (1). The limiting structure (10) comprises a clamping groove (101) provided on the pump body (1) and a clamping ring (102) provided above the positioning member (91). The clamping ring (102) is clamped with the clamping groove (101), and the clamping ring (102) is abutted against the positioning member (91).

5. The automobile brake master cylinder according to claim 2 or 3, characterized in that: The positioning column (92) is detachably connected to the assembly body (8).

6. The automobile brake master cylinder according to claim 1, 2 or 3, characterized in that: The second piston (5) is provided with a push rod (11) that can be pushed by the first piston (3), and the pump body (1) is provided with a first adjustment structure (12) that can adjust the distance between the push rod (11) and the first piston (3).

7. The automobile brake master cylinder according to claim 6, characterized in that: The first adjustment structure (12) includes a first internal thread (121) provided on the second piston (5), a first external thread (122) provided on the outside of the push rod (11) and matching the first internal thread (121), and a first force-bearing portion (123) provided on the push rod (11). The first force-bearing portion (123) can be forced to drive the push rod (11) to rotate.

8. The automobile brake master cylinder according to claim 1, 2 or 3, characterized in that: The bottom of the pump body (1) is provided with a through hole (16) for allowing an adjusting tool to extend into the interior of the pump body (1).

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