A two-stage hydraulic power-assisted master cylinder

Abstract

The present invention relates to a two-stage hydraulic power-assisted master cylinder. The cylinder body side is formed with a pressure oil port, a tank oil port, a first oil cup oil port, a first brake oil port, a second oil cup oil port, and a second brake oil port in sequence from rear to front along the axial direction. A power-assisted rod, a power-assisted piston rod, a first-stage piston rod, and a second-stage piston are arranged in sequence from rear to front along the axial direction within the cylinder body. The cylinder body cavity includes a power-assisted chamber, an intermediate chamber, a first master cylinder brake chamber, and a second master cylinder brake chamber. The present invention has a high hydraulic power assist, reducing pedal operating force and improving driver comfort; a large brake displacement, suitable for a wider range of engineering vehicles; and a compact structure, making it easier to install on vehicles.

Description

Technical Field

[0001] The present invention relates to the field of hydraulic engineering, in particular to a dual-stage hydraulic power-assisted master cylinder. Background Art

[0002] In the existing braking systems of engineering machinery vehicles, there are mainly three types:

[0003] Category 1 fully hydraulic brake system: safe, reliable, and comfortable to operate, but high in cost, mainly used in high-end models;

[0004] The second type of gas-assisted braking system: high failure rate, poor comfort, unsafe, high maintenance cost, and requires a separate air source, many components, complex space layout, high noise, poor safety, low temperature and difficulty in exhausting, which can easily lead to brake failure and high maintenance cost;

[0005] The third type of hydraulic power-assisted braking system: safe, reliable, and comfortable to operate. It has low cost and does not require matching charging valves and accumulators, etc. It can be applied to engineering machinery vehicles with low brake displacement and low vehicle tonnage.

[0006] Therefore, for some small-tonnage engineering machinery vehicles, the best braking system matching choice is the hydraulic power-assisted braking system, which can take into account low cost, safety and comfort. The hydraulic power-assisted system can use high-pressure oil power provided by a dedicated oil pump, or it can share the high-pressure oil power provided by the steering pump with the steering system to meet the control performance requirements of different customers.

[0007] There are two types of brake master cylinders: 1. Single-chamber type: suitable for single-circuit brake systems; 2. Dual-chamber type: suitable for dual-circuit brake systems. The present invention is a dual-chamber type;

[0008] The braking effect of the existing brake master cylinder is not ideal in actual application, mainly due to the following reasons:

[0009] 1) Low brake displacement and insufficient braking;

[0010] 2) Low brake pressure and high pedal operating force;

[0011] 3) The structural dimensions are too large, making installation inconvenient. Summary of the Invention

[0012] The present invention aims to solve the above problems and provides a two-stage hydraulic power-assisted master cylinder, which solves the problems of low brake displacement and insufficient braking in the prior art, solves the problems of low brake pressure and large pedal operating force in the prior art, and solves the problems of large structural size and inconvenient installation in the prior art.

[0013] A two-stage hydraulic power-assisted master cylinder comprises: a cylinder body, a power-assisted rod, a power-assisted piston rod, a primary piston rod and a secondary piston; the side surface of the cylinder body is formed with a pressure oil port, a tank oil port, a first oil cup oil port, a first brake oil port, a second oil cup oil port and a second brake oil port in sequence from back to front along the axial direction; the power-assisted rod, the power-assisted piston rod, the primary piston rod and the secondary piston are arranged in sequence from back to front along the axial direction inside the cylinder body; the inner cavity of the cylinder body comprises a power-assisted chamber, an intermediate chamber, a first master cylinder brake chamber and a second master cylinder brake chamber; the power-assisted chamber is located at one end of the power-assisted piston rod close to the power-assisted rod, and the intermediate chamber is located at the end of the power-assisted piston rod close to the primary piston rod one end and is located between the outer side of the first-level piston rod and the inner wall of the cylinder body, the first master cylinder brake chamber is located between the first-level piston rod and the second-level piston, the second master cylinder brake chamber is located between the second-level piston and the end of the cylinder body, the pressure oil port is connected with the power-boosting chamber through a first one-way valve, the first brake oil port is connected with the first master cylinder brake chamber, the second brake oil port is connected with the second master cylinder brake chamber, the first oil cup oil port is connected with the first master cylinder brake chamber through a second one-way valve, the second oil cup oil port is connected with the second master cylinder brake chamber through the position change of the secondary piston, and the tank oil port is connected with the cavity outside the power-boosting piston rod.

[0014] On the basis of the above technical solution, the cylinder body includes a tail end plug, a booster cylinder body, screws and a master cylinder body, the booster cylinder body is fixedly connected to the master cylinder body by screws, the tail end plug is fixedly connected to the end of the master cylinder body away from the booster cylinder body, the booster rod is slidably connected to the booster cylinder body, and the primary piston rod and the secondary piston are respectively slidably connected to the master cylinder body;

[0015] It also includes a fifth spring and an eighth spring, the two ends of the eighth spring are in contact with the tail end plug and the secondary piston respectively, one end of the fifth spring is in contact with the end of the secondary piston, and the other end is fixed to the position of the primary piston rod.

[0016] On the basis of the above technical solution, it also includes a protective sleeve, a retaining ring for the first hole and a retaining ring. The protective sleeve is fixedly connected to the end of the power-assisting cylinder body away from the main cylinder body. The retaining ring for the first hole and the retaining ring are located inside the power-assisting cylinder body to limit the power-assisting rod.

[0017] Based on the above technical solution, the cylinder body also includes a fourth O-ring and a seventh O-ring. The fourth O-ring is located between the power-assisting cylinder body and the main cylinder body to play a sealing role, and the seventh O-ring is located between the main cylinder body and the tail end plug to play a sealing role.

[0018] Based on the above technical solution, the first one-way valve includes a first spring, a second spring, a first steel ball, a positioning cone and a sealing sleeve. The inner cavity of the power-boosting rod is connected to the pressure oil port. The first spring is located inside the inner cavity of the power-boosting rod. The two ends of the first spring are respectively fixedly connected to the inner wall of the power-boosting rod and the first steel ball. The first steel ball is in contact with the sealing sleeve. The sealing sleeve is located inside the inner cavity of the power-boosting rod and is fixedly connected to the power-boosting rod. The positioning cone partially penetrates into the interior of the sealing sleeve. The two ends of the second spring are respectively in contact with the positioning cone and the sealing sleeve. An outer conical surface is formed on the end of the positioning cone away from the sealing sleeve, and the outer conical surface is adapted to the inner conical surface of the inner cavity of the rear end of the power-boosting piston rod.

[0019] Based on the above technical solution, it also includes a combined seal and a first O-ring. The combined seal is mounted on the outside of the power-assisting rod to provide a seal. The first O-ring is mounted on the outside of the power-assisting rod to provide a seal. The combined seal and the first O-ring prevent hydraulic oil from the pressure oil port from overflowing into other chambers. The first O-ring, copper sleeve, sealing washer, and retaining ring are retained in position by a retaining ring in the power-assisting cylinder and the second hole. The power-assisting rod is slidably connected to the first O-ring and copper sleeve.

[0020] On the basis of the above technical solution, it also includes a third O-ring, a guide ring and a booster piston. The booster piston is mounted on the outside of the booster piston rod and fixedly connected to the booster piston rod. The third O-ring and the guide ring are respectively mounted on the outside of the booster piston. The third O-ring is respectively fitted with the booster piston and the booster cylinder body, and the guide ring is respectively fitted with the booster piston and the booster cylinder body.

[0021] Based on the above technical solution, it also includes a first shaft retaining ring and a second O-ring. The first shaft retaining ring is mounted on the outside of the power-boosting piston rod and fixed to the power-boosting piston rod. The two ends of the power-boosting piston are in contact with the first shaft retaining ring and the shaft shoulders of the power-boosting piston rod respectively.

[0022] On the basis of the above technical solution, it also includes a positioning sleeve, a fifth O-ring and a sixth O-ring. The positioning sleeve is located at the connection between the power-boosting cylinder body and the master cylinder body and is pressed and fixed by the power-boosting cylinder body and the master cylinder body. The fifth O-ring is sleeved on the outside of the positioning sleeve and fits with the positioning sleeve and the master cylinder body respectively. The sixth O-ring is located in the annular groove on the inner side of the positioning sleeve and fits with the positioning sleeve and the power-boosting piston rod respectively. The power-boosting piston rod is slidably connected to the positioning sleeve, and the cavity outside the power-boosting piston rod is located between the power-boosting piston and the positioning sleeve.

[0023] Based on the above technical solution, it also includes an annular sleeve, a first piston seal and a fourth spring. The first piston seal is mounted on the outside of the power-boosting piston rod, and the two ends of the first piston seal are in contact with the annular sleeve and the fourth spring respectively. The annular sleeve is mounted on the outside of the power-boosting piston rod and the end thereof is in contact with the power-boosting piston rod. The outer side of the annular sleeve is an arc surface, and the fourth spring is in contact with the power-boosting piston rod.

[0024] Based on the above technical solution, the second one-way valve includes a third spring, an annular sealing sleeve, a second steel ball, a push rod, a flat sealing sleeve, a spring seat, an annular guide, and a ninth spring.

[0025] The third spring, the annular sealing sleeve and the second steel ball are located in the front end inner cavity of the booster piston rod. The two ends of the third spring are in contact with the inner wall of the booster piston rod and the second steel ball respectively. The annular sealing sleeve is fixedly connected to the booster piston rod. The second steel ball is adapted to the annular sealing sleeve.

[0026] The push rod passes through the primary piston rod and partially penetrates into the annular sealing sleeve. The spring seat is located inside the primary piston rod. The end of the fifth spring contacts the spring seat. The spring seat contacts the inner wall of the primary piston rod. The annular guide and the ninth spring are located inside the spring seat. The two ends of the ninth spring contact the inner wall of the spring seat and the annular guide respectively. The planar sealing sleeve is fixed to the annular guide. The end of the planar sealing sleeve is adapted to the inner wall of the end of the primary piston rod.

[0027] The second one-way valve also includes a retaining ring for a third hole, a push rod sleeve, a brass washer and a guide sealing assembly. The guide sealing assembly is located inside the spring seat, and the guide sealing assembly is sleeved on the outside of the annular guide and contacts the annular guide and the spring seat respectively. Both sides of the brass washer contact the retaining ring for the third hole and the guide sealing assembly respectively. The retaining ring for the third hole is fixedly connected to the spring seat, and the end of the push rod away from the second steel ball is fixedly connected to the push rod sleeve.

[0028] On the basis of the above technical solution, it also includes a primary lip seal, a secondary lip seal and a second piston seal. The primary lip seal is fixed and fitted with the master cylinder body. The inner side of the primary lip seal is adapted to the primary piston rod. The inner and outer sides of the secondary lip seal are fitted with the secondary piston and the master cylinder body respectively. The inner and outer sides of the second piston seal are fitted with the secondary piston and the master cylinder body respectively. The outer side of the second piston seal is a curved surface.

[0029] It also includes a secondary annular sleeve and a seventh spring. The secondary annular sleeve is sleeved on the outside of the secondary piston. The secondary annular sleeve and the seventh spring are respectively located on both sides of the second piston seal. The end of the seventh spring away from the second piston seal is in contact with the secondary piston.

[0030] Based on the above technical solution, the first oil cup oil port and the second oil cup oil port, the first oil cup oil port is connected to the front end cavity of the power piston rod through the first oil return port and the first oil return throttle port respectively, the first oil return throttle port is located on the side close to the first brake oil port, and the minimum inner diameter of the first oil return throttle port is smaller than the inner diameter of the first oil return port,

[0031] The second oil cup oil port is connected to the cylinder body cavity through the second oil return port and the second oil return throttle port respectively. The second oil return throttle port is connected to the second master cylinder brake chamber. The minimum inner diameter of the second oil return throttle port is smaller than the second oil return port.

[0032] Based on the above technical solution, the positioning sleeve divides the cavity outside the power-boosting piston rod into a rear end cavity and a front end cavity. The rear end inner cavity of the power-boosting piston rod is connected to the rear end cavity, the rear end cavity is connected to the oil port of the oil tank, and the front end cavity is connected to the oil port of the first oil cup.

[0033] The present invention has the following advantages: 1) large hydraulic power assist, which reduces the operating force of the pedal and improves the driver's operating comfort; 2) large brake displacement, which can meet the needs of more engineering machinery vehicles; 3) small structural size, which is easier to install on the vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only one embodiment of the present invention. Those skilled in the art can also derive other implementation drawings based on the provided drawings without inventive effort.

[0035] Figure 1 : Hydraulic principle diagram of the present invention;

[0036] Figure 2 : Schematic diagram of the three-dimensional structure of the present invention;

[0037] Figure 3 : A schematic diagram of a left-side sectional structure of the present invention in its initial state;

[0038] Figure 4 : A schematic diagram of the left side cross-sectional structure of the present invention in the pressure-building state;

[0039] Figure 5 : A schematic diagram of the left side cross-sectional structure of the present invention in the maximum displacement state;

[0040] Figure 6 : Figure 3 A partial enlarged view of point A in the middle;

[0041] Figure 7 : Figure 3 A partial enlarged view of point B in the middle;

[0042] Figure 8 : Figure 3 A partial enlarged view of point C in the middle;

[0043] In the figure, 1, protective sleeve; 2, retaining ring for the first hole; 3, retaining ring; 4, combined seal; 5, first O-ring; 6, copper sleeve; 7, sealing gasket; 8, booster rod; 9, first spring; 10, limit ring; 11, 1. Retaining ring for second hole; 2. Second spring; 3. First steel ball; 4. Positioning cone; 5. Wire retaining ring; 6. Retaining ring for first shaft; 7. Seal sleeve; 8. Second O-ring; 9. Third O-ring; 10. Guide ring; 11. Fourth O-ring; 12. Positioning sleeve; 13. Fifth O-ring; 14. Sixth O-ring; 15. Booster piston; 16. Booster piston rod; 17. Third spring; 18. Annular sleeve; 19. First piston seal; 20. Fourth spring; 21. First lip seal; 22. Annular seal sleeve; 23. Second steel ball; 24. Push rod; 25. Planar seal sleeve; 26. Spring seat; 27. First piston rod; 28. Brass washer; 29. ​​Guide seal assembly; 30. Fourth spring; 31. First lip seal; 32. Annular seal sleeve; 33. Second steel ball; 34. Push rod; 35. Planar seal sleeve; 36. Spring seat; 37. First piston rod; 38. Retaining ring for third hole; 39. Push rod sleeve; 40. Brass washer; 41. Guide seal assembly; 42. Annular guide; 43. , ninth spring; 44, fifth spring; 45, secondary lip seal; 46, sixth spring; 47, secondary piston; 48, second piston seal; 49, secondary annular sleeve; 50, seventh spring; 51, eighth spring; 52, seventh O-ring; 53, tail end plug; 54, power-assisting cylinder body; 55, screw; 56, master cylinder body; 001, power-assisting chamber; 101, first master cylinder brake chamber; 102, first return oil port; 103, first return oil throttle port; 110, intermediate chamber; 201, second master cylinder brake chamber; 202, second return oil port; 203, second return oil throttle port; P, pressure oil port; T, tank oil port; R1, first oil cup oil port; R2, second oil cup oil port; B1, brake oil port; B2, brake oil port. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to the accompanying drawings and examples:

[0045] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0046] In the description of the present invention, it should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0047] In the description of the present invention, it should be understood that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0048] Example 1:

[0049] like Figures 1 to 8 As shown, this embodiment provides a two-stage hydraulic power-assisted master cylinder, including: a cylinder body, a power-assisted rod 8, a power-assisted piston rod 26, a primary piston rod 37 and a secondary piston 47. The side surface of the cylinder body is formed with a pressure oil port P, a tank oil port T, a first oil cup oil port R1, a first brake oil port B1, a second oil cup oil port R2 and a second brake oil port B2 in sequence along the axial direction from back to front. The power-assisted rod 8, the power-assisted piston rod 26, the primary piston rod 37 and the secondary piston 47 are arranged in sequence along the axial direction from back to front inside the cylinder body. The inner cavity of the cylinder body includes a power-assisted chamber 001, an intermediate chamber 110, a first master cylinder brake chamber 101 and a second master cylinder brake chamber 201. The power-assisted chamber 001 is located at the end of the power-assisted piston rod 26 close to the power-assisted rod 8, and the intermediate chamber 110 is located at the end of the power-assisted piston rod 26 close to the power-assisted rod Near one end of the first-level piston rod 37 and located between the outer side of the first-level piston rod 37 and the inner wall of the cylinder body, the first master cylinder brake chamber 101 is located between the first-level piston rod 37 and the second-level piston 47, and the second master cylinder brake chamber 201 is located between the second-level piston 47 and the end of the cylinder body. The pressure oil port P is connected to the power-boosting chamber 001 through a first one-way valve, the first brake oil port B1 is connected to the first master cylinder brake chamber 101, and the second brake oil port B2 is connected to the second master cylinder brake chamber 201. The first oil cup oil port R1 is connected to the first master cylinder brake chamber 101 through a second one-way valve, and the second oil cup oil port R2 is connected to the second master cylinder brake chamber 201 through the position change of the second piston 47, and the oil tank oil port T is connected to the cavity outside the power-boosting piston rod 26.

[0050] Based on the above technical solution, the cylinder body includes a tail plug 53, a booster cylinder body 54, a screw 55, and a master cylinder body 56. The booster cylinder body 54 is fixedly connected to the master cylinder body 56 via the screw 55. The tail plug 53 is fixedly connected to the end of the master cylinder body 56 away from the booster cylinder body 54. The booster rod 8 is slidably connected to the booster cylinder body 54. The primary piston rod 37 and the secondary piston 47 are respectively slidably connected to the master cylinder body 56. The axial through hole of the tail plug 53 can also be connected to a brake. When the tail plug 53 is not required to be connected to a brake, the axial through hole is sealed with a seal (not shown).

[0051] It also includes a fifth spring 44 and an eighth spring 51 , the two ends of the eighth spring 51 are in contact with the tail end plug 53 and the secondary piston 47 respectively, one end of the fifth spring 44 is in contact with the end of the secondary piston 47 , and the other end is fixed in position with the primary piston rod 37 .

[0052] On the basis of the above technical solution, it also includes a protective sleeve 1, a first hole retaining ring 2 and a retaining ring 3. The protective sleeve 1 is fixedly connected to the end of the power-assisting cylinder body 54 away from the main cylinder body 56. The first hole retaining ring 2 and the retaining ring 3 are located inside the power-assisting cylinder body 54, and play a role in limiting the power-assisting rod 8.

[0053] Based on the above technical solution, the cylinder body also includes a fourth O-ring 21 and a seventh O-ring 52. The fourth O-ring 21 is located between the power-assisting cylinder body 54 and the master cylinder body 56 to play a sealing role, and the seventh O-ring 52 is located between the master cylinder body 56 and the tail end plug 53 to play a sealing role.

[0054] Based on the above technical solution, the first one-way valve includes a first spring 9, a second spring 12, a first steel ball 13, a positioning cone 14 and a sealing sleeve 17. The inner cavity of the power-boosting rod 8 is connected to the pressure oil port P. The first spring 9 is located inside the inner cavity of the power-boosting rod 8. The two ends of the first spring 9 are respectively fixedly connected to the inner wall of the power-boosting rod 8 and the first steel ball 13. The first steel ball 13 is in contact with the sealing sleeve 17. The sealing sleeve 17 is located inside the inner cavity of the power-boosting rod 8 and is fixedly connected to the power-boosting rod 8. The positioning cone 14 partially penetrates into the sealing sleeve 17. The two ends of the second spring 12 are respectively in contact with the positioning cone 14 and the sealing sleeve 17. The end of the positioning cone 14 away from the sealing sleeve 17 is formed with an outer conical surface, and the outer conical surface is adapted to the inner conical surface of the inner cavity of the rear end of the power-boosting piston rod 26.

[0055] Based on the above technical solution, it also includes a combined seal 4 and a first O-ring 5. The combined seal 4 is mounted on the outside of the booster rod 8 to provide a seal. The first O-ring 5 is mounted on the outside of the booster rod 8 to provide a seal. The combined seal 4 and the first O-ring 5 prevent hydraulic oil from the pressure oil port P from overflowing into other chambers. The first O-ring 5, copper sleeve 6, sealing washer 7, and retaining ring 10 are retained in position by a retaining ring 11 between the booster cylinder 54 and the second hole. The booster rod 8 is slidably connected to the first O-ring 5 and copper sleeve 6.

[0056] On the basis of the above technical solution, it also includes a third O-ring 19, a guide ring 20 and a booster piston 25. The booster piston 25 is sleeved on the outside of the booster piston rod 26 and fixedly connected to the booster piston rod 26. The third O-ring 19 and the guide ring 20 are respectively sleeved on the outside of the booster piston 25. The third O-ring 19 is respectively fitted with the booster piston 25 and the booster cylinder body 54. The guide ring 20 is respectively fitted with the booster piston 25 and the booster cylinder body 54.

[0057] On the basis of the above technical solution, it also includes a first shaft retaining ring 16 and a second O-ring 18. The first shaft retaining ring 16 is sleeved on the outside of the booster piston rod 26 and fixed to the booster piston rod 26. The two ends of the booster piston 25 are in contact with the shaft shoulders of the first shaft retaining ring 16 and the booster piston rod 26 respectively.

[0058] On the basis of the above technical solution, it also includes a positioning sleeve 22, a fifth O-ring 23 and a sixth O-ring 24. The positioning sleeve 22 is located at the connection between the power-boosting cylinder body 54 and the master cylinder body 56 and is pressed and fixed by the power-boosting cylinder body 54 and the master cylinder body 56. The fifth O-ring 23 is sleeved on the outside of the positioning sleeve 22 and fits with the positioning sleeve 22 and the master cylinder body 56 respectively. The sixth O-ring 24 is located in the annular groove on the inner side of the positioning sleeve 22 and fits with the positioning sleeve 22 and the power-boosting piston rod 26 respectively. The power-boosting piston rod 26 is slidably connected to the positioning sleeve 22. The cavity outside the power-boosting piston rod 26 is located between the power-boosting piston 25 and the positioning sleeve 22.

[0059] On the basis of the above technical solution, it also includes an annular sleeve 28, a first piston seal 29 and a fourth spring 30. The first piston seal 29 is sleeved on the outside of the booster piston rod 26, and the two ends of the first piston seal 29 are in contact with the annular sleeve 28 and the fourth spring 30 respectively. The annular sleeve 28 is sleeved on the outside of the booster piston rod 26 and the end thereof is in contact with the booster piston rod 26. The outer side of the annular sleeve 28 is an arc surface, and the fourth spring 30 is in contact with the booster piston rod 26.

[0060] Based on the above technical solution, the second one-way valve includes a third spring 27, an annular sealing sleeve 32, a second steel ball 33, a push rod 34, a flat sealing sleeve 35, a spring seat 36, an annular guide 42, and a ninth spring 43.

[0061] The third spring 27, the annular sealing sleeve 32 and the second steel ball 33 are located in the front end cavity of the booster piston rod 26. The two ends of the third spring 27 are in contact with the inner wall of the booster piston rod 26 and the second steel ball 33 respectively. The annular sealing sleeve 32 is fixedly connected to the booster piston rod 26. The second steel ball 33 is adapted to the annular sealing sleeve 32.

[0062] The push rod 34 passes through the primary piston rod 37 and partially penetrates into the annular sealing sleeve 32. The spring seat 36 is located inside the primary piston rod 37. The end of the fifth spring 44 contacts the spring seat 36. The spring seat 36 contacts the inner wall of the primary piston rod 37. The annular guide 42 and the ninth spring 43 are located inside the spring seat 36. The two ends of the ninth spring 43 contact the inner wall of the spring seat 36 and the annular guide 42 respectively. The planar sealing sleeve 35 is fixed to the annular guide 42. The end of the planar sealing sleeve 35 is adapted to the inner wall of the end of the primary piston rod 37.

[0063] The second one-way valve also includes a third hole retaining ring 38, a push rod sleeve 39, a brass washer 40 and a guide sealing assembly 41. The guide sealing assembly 41 is located inside the spring seat 36. The guide sealing assembly 41 is sleeved on the outside of the annular guide 42 and contacts the annular guide 42 and the spring seat 36 respectively. The two sides of the brass washer 40 contact the third hole retaining ring 38 and the guide sealing assembly 41 respectively. The third hole retaining ring 38 is fixedly connected to the spring seat 36. The end of the push rod 34 away from the second steel ball 33 is fixedly connected to the push rod sleeve 39.

[0064] On the basis of the above technical solution, the invention further includes a primary lip seal 31, a secondary lip seal 45 and a second piston seal 48. The primary lip seal 31 is fixed to and fits with the master cylinder body 56. The inner side of the primary lip seal 31 is adapted to the primary piston rod 37. The inner and outer sides of the secondary lip seal 45 fit with the secondary piston 47 and the master cylinder body 56 respectively. The inner and outer sides of the second piston seal 48 fit with the secondary piston 47 and the master cylinder body 56 respectively. The outer side of the second piston seal 48 is a curved surface.

[0065] It also includes a secondary annular sleeve 49 and a seventh spring 50. The secondary annular sleeve 49 is sleeved on the outside of the secondary piston 47. The secondary annular sleeve 49 and the seventh spring 50 are respectively located on both sides of the second piston seal 48. The end of the seventh spring 50 away from the second piston seal 48 is in contact with the secondary piston 47.

[0066] On the basis of the above technical solution, the first oil cup oil port R1 and the second oil cup oil port R2, the first oil cup oil port R1 is connected to the front end cavity of the power piston rod 26 through the first return oil port 102 and the first return oil throttle port 103 respectively, the first return oil throttle port 103 is located on the side close to the first brake oil port B1, and the minimum inner diameter of the first return oil throttle port 103 is smaller than the inner diameter of the first return oil port 102,

[0067] The second oil cup oil port R2 is connected to the cylinder body cavity through the second oil return port 202 and the second oil return throttle port 203 respectively. The second oil return throttle port 203 is connected to the second master cylinder brake chamber 201. The minimum inner diameter of the second oil return throttle port 203 is smaller than the second oil return port 202.

[0068] Based on the above technical solution, the positioning sleeve 22 divides the cavity outside the power-boosting piston rod 26 into a rear end cavity and a front end cavity. The rear end inner cavity of the power-boosting piston rod 26 is connected to the rear end cavity, the rear end cavity is connected to the oil tank port T, and the front end cavity is connected to the first oil cup oil port R1.

[0069] Working principle:

[0070] The pressure port P connects to an accumulator or hydraulic pump, the tank port T connects to the hydraulic tank, the first and second oil cup ports R1 and R2 connect to the oil cups, and the first and second brake ports B1 and B2 connect to the brakes. Due to the use of an intermediate chamber, the displacement of the first brake port B1 is greater than that of the second brake port B2, allowing it to accommodate brakes of different displacements on the vehicle's front and rear axles.

[0071] Initial state:

[0072] Hydraulic oil from pressure port P flows through booster rod 8 and into its inner cavity, where it is blocked by the first check valve. This generates a leftward force on booster rod 8: F = p*π*(d1² - d2²) / 4. Booster rod 8 is a stepped shaft with a diameter of d1 at its larger end and d2 at its smaller end. This hydraulic pressure forces the rear end of booster rod 8 into contact with retaining ring 3.

[0073] The right end of the eighth spring 51 abuts the inner end surface of the tail-end plug 53. The left end of the eighth spring 51 pushes the left end of the secondary piston 47 against the inner limit stop of the master cylinder body 5. Initially, the spring force of the eighth spring 51 is greater than the spring force of the fifth spring 44. The right end of the fifth spring 44 abuts the secondary piston 47, while the left end abuts the stop of the serial spring seat 36. Its spring force pushes the spring seat 36 against the inner end surface of the primary piston rod 37, and its spring force pushes the left end surface of the primary piston rod 37 against the right end surface of the booster piston rod 26. At this point, the left end of the booster piston 25 abuts the second hole retaining ring 11.

[0074] Under the action of the first spring 9, the first steel ball 13 fits against the sealing sleeve 17 to cut off the pressure at the pressure oil port P. In the initial state, the first steel ball 13 and the sealing sleeve 17 fit together. The positioning cone 14 and the booster piston rod 26 fit together to cut off the connection between the pressure oil port P and the tank port T. In the initial state, the positioning cone 14 and the booster piston rod 26 do not fit together.

[0075] In the initial state, under the action of the spring force of the third spring 27 , the second steel ball 33 is attached to the annular sealing sleeve 32 to cut off the oil connecting the first oil cup oil port R1 and the intermediate chamber 110 .

[0076] The first oil cup port R1 communicates with the intermediate chamber 110 and the first master cylinder brake chamber 101 via the first oil return port 102 and the first oil return throttle port 103. Initially, only the first oil return port 102 is connected to the inner chamber at the front end of the booster piston rod 26. Under atmospheric pressure, hydraulic oil from the oil cup is injected into these two chambers.

[0077] The second oil cup port R2 communicates with the secondary master cylinder brake chamber 201 via the second oil return port 202 and the second oil return throttle port 203. Initially, only the second oil return throttle port 203 communicates with the secondary master cylinder brake chamber 201. Under atmospheric pressure, hydraulic oil from the oil cup is injected into the secondary master cylinder brake chamber 201.

[0078] The flat sealing sleeve 35 (rubber piece) is sleeved on the annular guide 42 . Under the spring force of the ninth spring 43 , the flat sealing sleeve 35 is pressed against the inner end surface of the first-stage piston rod 37 for sealing in the initial state.

[0079] Pressure buildup status:

[0080] When the pedal is stepped on, the pedal push rod 56 moves forward, driving the positioning cone 14 to move forward until it cuts into the inner conical surface of the booster piston rod 26. The front end of the pedal push rod 56 is inserted into the groove at the rear end of the booster rod 8. Figures 3 to 5 As the booster rod 8 continues to move forward, its front end faces contact the rear end faces of the booster piston rod 26. The reaction force pushes the positioning cone 14 backward, pushing the steel ball 13 away from the sealing sleeve 17. A gap now forms between the steel ball 13 and the sealing sleeve 17, allowing the pressurized oil from the pressure port P to flow into the booster chamber 001. At this point, the positioning cone 14 and the booster piston rod 26 are in close contact and sealed, and the pressurized oil entering the pressure port P acts on the booster chamber 001, generating a boosting thrust of: F = p*π*(d² - d1²) / 4, where d is the diameter of the booster piston 25 and d1 is the diameter of the larger end of the booster rod 8.

[0081] As the pedal push rod 56 moves forward, the booster piston 25 moves forward under the action of the thrust generated by stepping on the pedal and the hydraulic boost force, while pushing the primary piston rod 37 forward, causing the first piston seal 29 to pass over the first return oil throttle port 103.

[0082] The intermediate chamber 110 forms a closed space with the interior of the primary master cylinder brake chamber 101 and the brake at the first brake oil port B1. During pressure buildup, as the pedal push rod 56 moves forward, hydraulic oil is first pushed into the brake piston chamber. Once the piston chamber is filled, the pressure in this chamber (piston chamber) begins to rise. Initially, the intermediate chamber 110 is connected to the primary master cylinder brake chamber 101 (via the gap between the primary piston rod 37 and the master cylinder body 56). Once the piston chamber is filled, the pressure in the intermediate chamber 110 and the primary master cylinder brake chamber 101 increases as a whole.

[0083] In the initial state, the primary piston rod 37 has not yet engaged with the primary lip seal 31. As the pedal push rod 56 continues to move forward, the primary piston rod 37 and the primary lip seal 31 are fully engaged, forming a seal. At this point, the intermediate chamber 110 is isolated from the primary master cylinder brake chamber 101, and the intermediate chamber 110 is sealed. As the pedal push rod 56 continues to move forward, the pressure in the intermediate chamber 110 increases, and the forward thrust of the annular guide 42 exceeds the spring force of the ninth spring 43, causing the flat seal 35 to separate from the inner end surface of the primary piston rod 37. The oil in the intermediate chamber 110 (via the through-hole in the sidewall of the spring seat 36) is again connected to the primary master cylinder brake chamber 101, thereby increasing the displacement output from the first brake oil port B1. As the oil pressure within the primary master cylinder brake chamber 101 increases, reaching a set value, the force acting on the push rod 34 becomes greater than the spring force of the third spring 27. This forces the push rod 34 to push the second steel ball 33 away from the annular seal 32. The pressurized oil in the intermediate chamber 110 flows through the gap between the second steel ball 33 and the annular seal 32 into the first oil cup opening R1 and into the oil cup. As the pedal push rod 56 continues to move forward, the oil pressure within the primary master cylinder brake chamber 101 continues to rise to the desired braking pressure.

[0084] As the pedal push rod 56 moves forward, the fifth spring 44 continues to compress, simultaneously increasing the pressure within the primary master cylinder brake chamber 101. When the combined force (thrust and hydraulic boost) exceeds the force of the eighth spring 51, the secondary piston 47 is pushed forward. The secondary lip seal 45, mounted within the sealing groove of the secondary piston 47, prevents the pressurized oil in the primary master cylinder brake chamber 101 from leaking into the second oil cup port R2. The second piston seal 48, mounted within the sealing groove at the right end of the secondary piston 47, is fitted with the seventh spring 50 to ensure contact with the secondary piston 47. As the secondary piston 47 moves forward, the second piston seal 48 passes over the second return oil throttle 203 of the second oil cup port R2, creating a closed chamber within the secondary master cylinder brake chamber 201 and the brake connected thereto. The oil first fills the brake piston chamber connected to brake port B2. Once the chamber is filled, the pressure gradually increases to the desired braking pressure.

[0085] Maximum displacement state:

[0086] like Figure 5 As shown, the seventh spring 50 contacts the tail end plug, and the pedal push rod 56 cannot move forward. At this time, the maximum displacement is reached.

[0087] Resetting the brake master cylinder:

[0088] After the vehicle is braked, the driver releases the pedal, and the booster rod 8 returns to its initial position. Due to the different areas of the booster rods 8 on both sides of the pressure oil port P, the pressure of the hydraulic oil causes the booster rod 8 to move backward. After the positioning cone 14 contacts the wire retaining ring 15, the positioning cone 14 is driven backward by the wire retaining ring 15, causing the sealing surface between the positioning cone 14 and the booster piston rod 26 to disengage. The booster hydraulic oil in the booster chamber 001 communicates with the oil tank port T from the rear end inner cavity of the booster piston rod 26, and the pressure in the booster chamber 001 drops to 0. Under the thrust of the eighth spring 51 and the fifth spring 44, the booster piston 25, the first piston rod 37, and the second piston 47 move to the left and return to their initial state; one braking operation is completed.

[0089] The present invention has been described above by way of examples, but the present invention is not limited to the above specific embodiments. Any changes or modifications based on the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A two-stage hydraulic power-assisted master cylinder, characterized in that: include: A cylinder body, a booster rod (8), a booster piston rod (26), a primary piston rod (37) and a secondary piston (47); the cylinder body side surface is formed with a pressure oil port (P), a tank oil port (T), a first oil cup oil port (R1), a first brake oil port (B1), a second oil cup oil port (R2) and a second brake oil port (B2) in sequence along the axial direction from back to front; the booster rod (8), the booster piston rod (26), the primary piston rod (37) and the secondary piston (47) are arranged in sequence along the axial direction from back to front inside the cylinder body; the inner cavity of the cylinder body includes a booster chamber (001), an intermediate chamber (110), a first master cylinder brake chamber (101) and a second master cylinder brake chamber (201); the booster chamber (001) is located at one end of the booster piston rod (26) close to the booster rod (8); the intermediate chamber (110) is located at the end of the booster piston rod (26) close to the primary piston rod (37) ) and is located between the outer side of the first piston rod (37) and the inner wall of the cylinder body, the first master cylinder brake chamber (101) is located between the first piston rod (37) and the second piston (47), the second master cylinder brake chamber (201) is located between the second piston (47) and the end of the cylinder body, the pressure oil port (P) is connected to the power-assisting chamber (001) through a first one-way valve, the first brake oil port (B1) is connected to the first master cylinder brake chamber (101), the second brake oil port (B2) is connected to the second master cylinder brake chamber (201), the first oil cup oil port (R1) is connected to the first master cylinder brake chamber (101) through a second one-way valve, the second oil cup oil port (R2) is connected to the second master cylinder brake chamber (201) through the position change of the second piston (47), and the oil tank oil port (T) is connected to the cavity outside the power-assisting piston rod (26); It also includes a fifth spring (44) and an eighth spring (51), wherein both ends of the eighth spring (51) are in contact with the tail end plug (53) and the secondary piston (47), respectively; one end of the fifth spring (44) is in contact with the end of the secondary piston (47), and the other end is fixed in position with the primary piston rod (37); The second one-way valve comprises a third spring (27), an annular sealing sleeve (32), a second steel ball (33), a push rod (34), a planar sealing sleeve (35), a spring seat (36), an annular guide (42) and a ninth spring (43). The third spring (27), the annular sealing sleeve (32) and the second steel ball (33) are located in the front end inner cavity of the booster piston rod (26). The two ends of the third spring (27) are in contact with the inner wall of the booster piston rod (26) and the second steel ball (33) respectively. The annular sealing sleeve (32) is fixedly connected to the booster piston rod (26). The second steel ball (33) is adapted to the annular sealing sleeve (32). The push rod (34) passes through the primary piston rod (37) and partially penetrates the inside of the annular sealing sleeve (32); the spring seat (36) is located inside the primary piston rod (37); the end of the fifth spring (44) contacts the spring seat (36); the spring seat (36) contacts the inner wall of the primary piston rod (37); the annular guide (42) and the ninth spring (43) are located inside the spring seat (36); the two ends of the ninth spring (43) contact the inner wall of the spring seat (36) and the annular guide (42) respectively; the planar sealing sleeve (35) is fixed to the annular guide (42); the end of the planar sealing sleeve (35) is adapted to the inner wall of the end of the primary piston rod (37); The second one-way valve further comprises a third hole retaining ring (38), a push rod sleeve (39), a brass washer (40) and a guide sealing assembly (41), wherein the guide sealing assembly (41) is located inside the spring seat (36), the guide sealing assembly (41) is sleeved on the outside of the annular guide (42) and contacts the annular guide (42) and the spring seat (36) respectively, the two sides of the brass washer (40) contact the third hole retaining ring (38) and the guide sealing assembly (41) respectively, the third hole retaining ring (38) is fixedly connected to the spring seat (36), and the end of the push rod (34) away from the second steel ball (33) is fixedly connected to the push rod sleeve (39).

2. The dual-stage hydraulic power-assisted master cylinder according to claim 1, characterized in that: The cylinder body comprises a tail end plug (53), a booster cylinder body (54), a screw (55) and a master cylinder body (56); the booster cylinder body (54) is fixedly connected to the master cylinder body (56) via the screw (55); the tail end plug (53) is fixedly connected to one end of the master cylinder body (56) away from the booster cylinder body (54); the booster rod (8) is slidably connected to the booster cylinder body (54); and the primary piston rod (37) and the secondary piston (47) are respectively slidably connected to the master cylinder body (56).

3. The dual-stage hydraulic power-assisted master cylinder according to claim 2, characterized in that: The first one-way valve comprises a first spring (9), a second spring (12), a first steel ball (13), a positioning cone (14) and a sealing sleeve (17). The inner cavity of the booster rod (8) is connected to the pressure oil port (P). The first spring (9) is located inside the inner cavity of the booster rod (8). The two ends of the first spring (9) are fixedly connected to the inner wall of the booster rod (8) and the first steel ball (13) respectively. The first steel ball (13) contacts the sealing sleeve (17). The sealing sleeve (17) is located inside the inner cavity of the booster rod (8) and is fixedly connected to the booster rod (8). The positioning cone (14) partially penetrates into the sealing sleeve (17). The two ends of the second spring (12) are respectively in contact with the positioning cone (14) and the sealing sleeve (17). An outer conical surface is formed on the end of the positioning cone (14) away from the sealing sleeve (17). The outer conical surface is adapted to the inner conical surface of the inner cavity of the rear end of the booster piston rod (26).

4. The dual-stage hydraulic power-assisted master cylinder according to claim 3, characterized in that: It also includes a third O-ring (19), a guide ring (20) and a booster piston (25), wherein the booster piston (25) is sleeved on the outside of the booster piston rod (26) and is fixedly connected to the booster piston rod (26), the third O-ring (19) and the guide ring (20) are sleeved on the outside of the booster piston (25), the third O-ring (19) is respectively fitted with the booster piston (25) and the booster cylinder (54), and the guide ring (20) is respectively fitted with the booster piston (25) and the booster cylinder (54).

5. The dual-stage hydraulic power-assisted master cylinder according to claim 4, characterized in that: The utility model further comprises a positioning sleeve (22), a fifth O-ring (23) and a sixth O-ring (24), wherein the positioning sleeve (22) is located at the connection between the booster cylinder body (54) and the master cylinder body (56) and is pressed and fixed by the booster cylinder body (54) and the master cylinder body (56), the fifth O-ring (23) is sleeved on the outside of the positioning sleeve (22) and fits with the positioning sleeve (22) and the master cylinder body (56) respectively, the sixth O-ring (24) is located in the annular groove on the inside of the positioning sleeve (22) and fits with the positioning sleeve (22) and the booster piston rod (26) respectively, the booster piston rod (26) is slidably connected to the positioning sleeve (22), and the cavity outside the booster piston rod (26) is located between the booster piston (25) and the positioning sleeve (22).

6. The dual-stage hydraulic power-assisted master cylinder according to claim 5, characterized in that: The invention also includes an annular sleeve (28), a first piston seal (29) and a fourth spring (30), wherein the first piston seal (29) is sleeved on the outside of the booster piston rod (26), and the two ends of the first piston seal (29) are in contact with the annular sleeve (28) and the fourth spring (30) respectively. The annular sleeve (28) is sleeved on the outside of the booster piston rod (26) and the end thereof is in contact with the booster piston rod (26), the outer side of the annular sleeve (28) is an arc surface, and the fourth spring (30) is in contact with the booster piston rod (26).

7. The dual-stage hydraulic power-assisted master cylinder according to claim 1, characterized in that: It also includes a primary lip seal (31), a secondary lip seal (45) and a second piston seal (48), wherein the primary lip seal (31) is fixed to and fitted with the main cylinder body (56), the inner side of the primary lip seal (31) is adapted to the primary piston rod (37), the inner and outer sides of the secondary lip seal (45) are fitted with the secondary piston (47) and the main cylinder body (56), the inner and outer sides of the second piston seal (48) are fitted with the secondary piston (47) and the main cylinder body (56), and the outer side of the second piston seal (48) is an arc surface; The utility model further comprises a secondary annular sleeve (49) and a seventh spring (50), wherein the secondary annular sleeve (49) is sleeved on the outside of the secondary piston (47), the secondary annular sleeve (49) and the seventh spring (50) are respectively located on both sides of the second piston seal (48), and the end of the seventh spring (50) away from the second piston seal (48) contacts the secondary piston (47).

8. The dual-stage hydraulic power-assisted master cylinder according to claim 1, characterized in that: The first oil cup oil port (R1) and the second oil cup oil port (R2) are connected to the front end cavity of the booster piston rod (26) through the first oil return port (102) and the first oil return throttle port (103), respectively. The first oil return throttle port (103) is located on the side close to the first brake oil port (B1). The minimum inner diameter of the first oil return throttle port (103) is smaller than the inner diameter of the first oil return port (102). The second oil cup oil port (R2) is connected to the inner cavity of the cylinder body through the second oil return port (202) and the second oil return throttle port (203), the second oil return throttle port (203) is connected to the second master cylinder brake chamber (201), and the minimum inner diameter of the second oil return throttle port (203) is smaller than the second oil return port (202).

9. The dual-stage hydraulic power-assisted master cylinder according to claim 5, characterized in that: The positioning sleeve (22) divides the cavity outside the booster piston rod (26) into a rear end cavity and a front end cavity. The rear end inner cavity of the booster piston rod (26) is connected to the rear end cavity, the rear end cavity is connected to the oil tank port (T), and the front end cavity is connected to the first oil cup port (R1).

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