Power-assisted braking device for braking

Abstract

The invention discloses a power-assisted braking device for braking in the technical field of vehicle braking, a first one-way valve is arranged on a cylinder body, a front variable cavity of the first one-way valve is communicated with an oil port of an oil tank in a one-way mode, a conical shaft sleeve which is arranged on a plug body and used for ejecting the first one-way valve is combined, and when the braking force reaches the maximum, the first one-way valve is opened; and when the first one-way valve is jacked open, the pressure oil in the front variable cavity flows back to the oil tank through the first one-way valve. The first one-way valve is mounted on the cylinder body, production and assembly difficulty is lowered, and maintenance and replacement are facilitated. The large cavity and the small cavity are formed in the cylinder body, the diameter of the large cavity is larger than that of the small cavity, when the first one-way valve is ejected open, the extrusion force of the piston on hydraulic oil in the small cavity can be increased in a multiplied mode, the good power-assisted braking effect is achieved, and the brake cylinder is suitable for large machines.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle braking, and in particular to a power-assisted braking device for braking. Background Art

[0002] At present, oil brakes are commonly used in vehicle braking devices, which use hydraulic oil to transmit braking force. When braking, the piston will squeeze the pressure oil in the cylinder into the oil circuit of the brake pad, so that the brake pad approaches and fits tightly against the brake disc, thus achieving a braking effect.

[0003] The force for the axial movement of the piston in the cylinder body comes from the driver's foot force and the pressure of the oil pump connected to the cylinder body. The hydraulic oil of the oil pump is pumped into the space behind the piston, forming a strong forward pressure on the piston, which is the main force driving the piston to move.

[0004] In the above-mentioned power-assisted braking device, the pressure generated by the hydraulic oil from the oil pump may be sufficient for general small vehicles, but the power-assisted braking effect for large machinery does not meet expectations; and when the brake pad is close to the brake disc and the braking force reaches the maximum, the above-mentioned power-assisted braking device allows the hydraulic oil to flow back to the oil tank through a one-way valve arranged in the piston. On the one hand, it is difficult to produce, and on the other hand, it is not convenient for replacement and maintenance. Summary of the invention

[0005] The purpose of the present invention is to provide a power-assisted braking device for braking, so as to solve the technical problems that in the existing power-assisted braking device, the pressure generated by the hydraulic oil from the oil pump cannot achieve the expected effect on the power-assisted braking of large machinery, and the power-assisted braking device allows the hydraulic oil to flow back to the oil tank through a one-way valve arranged in the piston when the braking force reaches the maximum, which is difficult to produce on the one hand and inconvenient to replace and repair on the other hand.

[0006] In order to solve the above technical problems, the present invention specifically provides a power-assisted brake device for braking, including a cylinder body, wherein a small cavity and a large cavity which are interconnected and distributed along the axial direction are arranged in the cylinder body, the diameter of the large cavity is larger than the diameter of the small cavity, and the position of the cylinder body corresponding to the large cavity is respectively provided with a tank oil port connected to the oil tank and an oil pump oil port connected to the oil pump, a branch connected to the large cavity is also arranged on the side of the tank oil port close to the small cavity, and a first one-way valve which is unidirectionally connected to the tank oil port is installed in the branch, and a brake oil port connected to a brake actuator is arranged on the side of the cylinder body away from the small cavity;

[0007] A piston is arranged in the cylinder body, a plug head of the piston is located in the small cavity, and an outer wall of the plug head is arranged on a plug head sealing ring, a front variable cavity and a rear variable cavity are respectively formed between the front and rear ends of the plug body of the piston and the cylinder body, a hole connecting the small cavity and the front variable cavity is arranged in the plug head, and a second one-way valve that conducts one-way to the small cavity is arranged in the hole;

[0008] A reversing valve core is arranged in the piston, a valve core inner cavity connected to the rear variable cavity is arranged at the center of the reversing valve core, an oil port and a sealing ring are arranged on the reversing valve core and the piston, and the reversing valve core can move axially to control the rear variable cavity to be connected to the oil port of the oil pump, so that the oil pump assists the movement of the piston to provide brake assistance, or the rear variable cavity is connected to the oil port of the oil tank, so that the pressure oil in the rear variable cavity flows back to the oil tank to relieve pressure;

[0009] The piston can move toward the front variable chamber to block the connection between the oil tank port and the front variable chamber, and pressurize the pressure oil in the front variable chamber into the small chamber to bring the brake pad close to the brake disc; the plug body is located at one end of the front variable chamber and is externally sleeved with a conical sleeve for pushing open the first one-way valve, so that when the braking force of the piston reaches the maximum, the pressure oil in the front variable chamber can flow back to the oil tank through the first one-way valve.

[0010] As a preferred solution of the present invention, the outer edge of the piston is sequentially provided with a first piston oil port, a first piston sealing ring, a second piston oil port, a second piston sealing ring, a third piston oil port and a third piston sealing ring in a direction away from the small cavity, each piston sealing ring is installed on the outward raised ring of the piston and is in close contact with the inner wall of the cylinder body, each piston oil port is used to connect the large cavity with the inner cavity of the piston, and the rear variable cavity is formed between the third piston sealing ring and the tail end of the cylinder body;

[0011] A reversing valve core capable of axial movement is arranged in the inner cavity of the piston, and the end of the reversing valve core away from the small cavity passes through the tail end of the cylinder body and is sealed with the cylinder body through a fourth valve core sealing ring, and a first valve core sealing ring, a first valve core oil port, a second valve core sealing ring, a third valve core sealing ring, a second valve core oil port and a third valve core oil port are sequentially arranged on the upper edge of the reversing valve core in a direction away from the small cavity, and the third valve core oil port is connected to the rear variable cavity.

[0012] As a preferred solution of the present invention, a piston spring is provided inside the piston sleeve in the front variable cavity, one end of the piston spring is sleeved on the plug body, and the other end is sleeved on a positioning ring extending from the separation surface of the large cavity and the small cavity toward the large cavity, and the conical sleeve is displaced outside the piston spring;

[0013] The positioning ring is provided with a positioning ring oil port for connecting the large cavity and the small cavity;

[0014] A reversing spring is arranged between one end of the reversing valve core close to the small cavity and the piston.

[0015] As a preferred solution of the present invention, a plug neck is further provided between the plug head and the plug body, the diameter of the plug neck is smaller than the diameter of the plug head and the diameter of the small cavity, and a channel connecting the front variable cavity and the small cavity is provided on the plug neck.

[0016] As a preferred solution of the present invention, an exhaust port is provided on the cylinder body at a position corresponding to the small cavity, a vent plug is installed in the exhaust port, the vent plug and the exhaust port are both stepped, and a sealing ring is provided outside the end of the vent plug with a smaller diameter.

[0017] As a preferred solution of the present invention, the first one-way valve includes a valve core with its head extending into the large cavity, a compression spring located at the tail of the valve core, and a sealing valve stem threadedly connected to the cylinder body for constraining the compression spring.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides a first one-way valve on the cylinder body for one-way communication between the front variable cavity and the oil port of the oil tank, and in combination with the conical sleeve provided on the plug body for pushing open the first one-way valve, when the braking force reaches the maximum, the first one-way valve is pushed open, and the pressure oil in the front variable cavity flows back to the oil tank through the first one-way valve. The first one-way valve is installed on the cylinder body, which reduces the difficulty of production and assembly, and is convenient for maintenance and replacement.

[0020] A large cavity and a small cavity are arranged in the cylinder body, and the diameter of the large cavity is larger than that of the small cavity. When the first one-way valve is pushed open, the squeezing force of the piston on the hydraulic oil in the small cavity can be increased several times, which has a good boost braking effect and is suitable for large machinery. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0022] Figure 1 It is a structural schematic diagram of the initial state of the braking device in an embodiment of the present invention;

[0023] Figure 2It is a schematic diagram of the structure of the brake device, brake disc and caliper in an embodiment of the present invention;

[0024] Figure 3 This is a schematic diagram of the structure when the reversing valve core just moves to the left end of the piston in an embodiment of the present invention;

[0025] Figure 4 It is a structural schematic diagram of the first piston sealing ring in the embodiment of the present invention when it is about to seal the oil tank oil port;

[0026] Figure 5 It is a structural schematic diagram of the first piston sealing ring in the embodiment of the present invention when it passes over the oil tank oil port;

[0027] Figure 6 It is the theoretical model for unassisted braking;

[0028] Figure 7 It is a structural schematic diagram of the tapered sleeve just contacting the first one-way valve in the embodiment of the present invention;

[0029] Figure 8 It is a schematic diagram of the structure when the conical sleeve pushes open the first one-way valve in the embodiment of the present invention;

[0030] Fig. 9 Theoretical model for power-assisted braking;

[0031] Fig.10 It is a structural schematic diagram of the piston in the embodiment of the present invention when it moves to the leftmost end;

[0032] Fig.11 It is a structural schematic diagram of the case where the piston moves to the leftmost end and the reversing valve core is reset to the right in an embodiment of the present invention.

[0033] The numbers in the figure represent the following:

[0034] 1-cylinder body, 2-small chamber, 3-large chamber, 4-tank oil port, 5-oil pump oil port, 6-branch, 7-first one-way valve, 8-brake oil port, 9-piston, 10-front variable chamber, 11-rear variable chamber, 12-second one-way valve, 13-reversing valve core, 14-valve core cavity, 15-conical sleeve, 16-first piston oil port, 17-first piston seal ring, 18-second piston oil port, 19-second piston seal ring, 20-third piston Plug oil port, 21-third piston sealing ring, 22-raised ring, 23-fourth valve core sealing ring, 24-first valve core sealing ring, 25-first valve core oil port, 26-second valve core sealing ring, 27-third valve core sealing ring, 28-second valve core oil port, 29-third valve core oil port, 30-piston spring, 31-positioning ring, 32-positioning ring oil port, 33-reversing spring, 34-plug head, 35-plug body, 36-plug neck, 37-bleed plug. DETAILED DESCRIPTION

[0035] 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.

[0036] The present invention specifically provides a power-assisted braking device for braking, the present invention specifically provides a power-assisted braking device for braking, comprising a cylinder body 1, wherein the cylinder body 1 is provided with a small cavity 2 and a large cavity 3 which are interconnected and distributed along the axial direction, wherein the diameter of the large cavity 3 is larger than the diameter of the small cavity 2, wherein the cylinder body 1 is provided with a tank oil port 4 connected to the oil tank and an oil pump oil port 5 connected to the oil pump at positions corresponding to the large cavity 3, wherein the tank oil port 4 is also provided with a branch 6 connected to the large cavity 3 on a side close to the small cavity 2, and a first one-way valve 7 which is unidirectionally connected to the tank oil port 4 is installed in the branch 6, and the cylinder body 1 is provided with a brake oil port 8 connected to a brake actuator on a side away from the small cavity 2;

[0037] A piston 9 is arranged in the cylinder body 1, a plug head 34 of the piston 9 is located in the small cavity 2, and an outer wall of the plug head 34 is arranged on a sealing ring of the plug head 34, a front variable cavity 10 and a rear variable cavity 11 are respectively formed between the front and rear ends of the plug body 35 of the piston 9 and the cylinder body 1, a hole connecting the small cavity 2 and the front variable cavity 10 is arranged in the plug head 34, and a second one-way valve 12 that conducts one-way to the small cavity 2 is arranged in the hole;

[0038] A reversing valve core 13 is provided in the piston 9, and a valve core inner cavity 14 communicating with the rear variable cavity 11 is provided at the center of the reversing valve core 13. Oil ports and sealing rings are provided on the reversing valve core 13 and the piston 9. The reversing valve core 13 can move axially to control the communication between the rear variable cavity 11 and the oil pump oil port 5, so that the oil pump assists the movement of the piston 9 to provide brake assistance, or the rear variable cavity 11 is connected to the oil tank oil port 4, so that the pressure oil in the rear variable cavity 11 flows back to the oil tank to relieve pressure;

[0039] The piston 9 can move toward the front variable chamber 10 to block the connection between the oil tank oil port 4 and the front variable chamber 10, and pressurize the pressure oil in the front variable chamber 10 into the small chamber 2 to make the brake pad close to the brake disc; the plug body 35 is located at one end of the front variable chamber 10 and is externally sleeved with a conical sleeve 15 for pushing open the first one-way valve 7, so that when the braking force of the piston 9 reaches the maximum, the pressure oil in the front variable chamber 10 can flow back to the oil tank through the first one-way valve 7.

[0040] In summary, the present invention is provided with a first one-way valve 7 on the cylinder body 1 for one-way communication between the front variable cavity 10 and the oil tank oil port 4, and in combination with the conical sleeve 15 provided on the plug body 35 for pushing open the first one-way valve 7, when the braking force reaches the maximum, the first one-way valve 7 is pushed open, and the pressure oil in the front variable cavity 10 flows back to the oil tank through the first one-way valve 7. The first one-way valve 7 is installed on the cylinder body, which reduces the difficulty of production and assembly, and is convenient for maintenance and replacement.

[0041] The present invention arranges a large chamber 3 and a small chamber 2 in the cylinder body 1. The diameter of the large chamber 3 is larger than the diameter of the small chamber 2. When the first one-way valve 7 is pushed open, the squeezing force of the piston on the hydraulic oil in the small chamber 2 can be increased several times, which has a good boost braking effect and is suitable for large machinery.

[0042] Furthermore, the outer edge of the piston 9 is provided with a first piston oil port 16, a first piston sealing ring 17, a second piston oil port 18, a second piston sealing ring 19, a third piston oil port 20 and a third piston sealing ring 21 in sequence in the direction away from the small cavity 2. Each piston sealing ring is installed on the outward raised ring 22 of the piston 9 and is in close contact with the inner wall of the cylinder body 1. Each piston oil port is used to connect the large cavity 3 with the inner cavity of the piston 9. The rear variable cavity 11 is formed between the third piston sealing ring 21 and the tail end of the cylinder body 1.

[0043] A reversing valve core 13 capable of axial movement is arranged in the inner cavity of the piston 9, and the end of the reversing valve core 13 away from the small cavity 2 passes through the tail end of the cylinder body 1 and is sealed with the cylinder body 1 through a fourth valve core sealing ring 23, and a first valve core sealing ring 24, a first valve core oil port 25, a second valve core sealing ring 26, a third valve core sealing ring 27, a second valve core oil port 28 and a third valve core oil port 29 are sequentially arranged on the upper edge of the reversing valve core 13 in the direction away from the small cavity 2, and the third valve core oil port 29 is connected to the rear variable cavity 11.

[0044] Furthermore, a piston spring 30 is provided in the front variable cavity 10 and outside the piston 9, one end of the piston spring 30 is sleeved on the plug body 35, and the other end is sleeved on a positioning ring 31 extending toward the direction of the large cavity 3 on the separation surface between the large cavity 3 and the small cavity 2, and the tapered sleeve 15 is displaced outside the piston spring 30;

[0045] The positioning ring 31 is provided with a positioning ring oil port 32 for connecting the large chamber 3 and the small chamber 2; when the piston 9 just starts to move forward, the first piston sealing ring 17 has not yet blocked the oil tank oil port 4 and the front variable chamber 10, the pressure in the front variable chamber 10 is very small, and the second one-way valve 12 is not opened. The piston positioning ring oil port 32 is used to connect the front variable chamber 10 and the small chamber 2, so that the pressure oil in the front variable chamber 10 can enter the small chamber 2, so that the small chamber 2 and the brake pad oil circuit are filled with hydraulic oil, so that the brake pad is close to the brake disc.

[0046] A reversing spring 33 is provided between the end of the reversing valve core 13 close to the small chamber 2 and the piston 9 .

[0047] Furthermore, a plug neck 36 is provided between the plug head 34 and the plug body 35 , the diameter of the plug neck 36 is smaller than the diameter of the plug head 34 and the diameter of the small cavity 2 , and a channel connecting the front variable cavity 10 and the small cavity 2 is provided on the plug neck 36 .

[0048] As a preferred solution of the present invention, an exhaust port is provided on the cylinder body 1 at a position corresponding to the small cavity 2, and a vent plug 37 is installed in the exhaust port. The vent plug 37 and the exhaust port are both stepped, and a sealing ring is provided outside the end of the vent plug 37 with a smaller diameter.

[0049] Furthermore, the first one-way valve 7 includes a valve core with its head extending into the large cavity 3, a compression spring located at the tail of the valve core, and a sealing valve stem threadedly connected to the cylinder body 1 for constraining the compression spring.

[0050] During operation, depending on the position of the reversing valve, there are non-power-assisted braking mode and power-assisted braking mode, and the power-assisted braking mode is the sequel to the non-power-assisted braking mode.

[0051] The working process of the brake device in the non-assist mode is described in detail below.

[0052] like Figure 1 As shown, the brake device is in an initial state, at which time the oil tank oil hole, the large chamber 3, the first piston 9 oil hole, the valve core chamber, the first valve core oil hole, the second piston 9 oil hole, the second valve core oil hole, the third valve core oil hole and the variable chamber are all connected to each other or indirectly.

[0053] At this time, the reversing valve core 13 and the piston 9 are in a balanced state / stationary state, and the small chamber 2 and the brake caliper oil chamber are filled with hydraulic oil. Figure 5 shown.

[0054] like Figure 3As shown, when the foot is on the brake pedal, the pedal transmits force to the reversing valve core 13, and the reversing valve core 13 moves left to the left end of the piston 9 (thereafter the reversing valve core 13 and the piston 9 are relatively stationary), the reversing spring 33 is compressed, the first valve core sealing ring 24 blocks the first piston oil port 16, the second valve core sealing ring 26 blocks the second piston oil port 18, and the third valve core sealing ring 27 passes over the third piston oil port 20, so that the third piston oil port 20, the oil pump oil port 5, the second valve core oil port 28, the third valve core oil port 29 and the variable volume cavity are connected, and the pressure oil from the oil pump is transmitted to the variable volume cavity at the right end of the cylinder body 1, forming a leftward pressure, which pushes the piston 9 to move leftward together with the pedal force. At this time, the oil in the small cavity 2 tends to move leftward (but has not moved yet).

[0055] Figure 4 and Figure 5 It is shown that the piston 9 continues to move to the left until the first piston seal ring 17 passes over the oil tank port 4, so that the oil tank port 4 is disconnected from the large chamber 3. At this time, the space where the piston spring 30 is located forms a closed chamber. As the piston 9 continues to move to the left, the oil in the chamber enters the small chamber 2 through the second one-way valve 12. When the friction plate on the brake caliper is in close contact with the brake disc on the wheel drum, the piston 9 and the reversing valve core 13 move to the left, and the actual effect is hydraulic transmission.

[0056] At this time, the theoretical model of hydraulic transmission is as follows Figure 6 As shown, it belongs to the non-assistance mode, and the specific principles are as follows:

[0057] according to Figure 6 Theoretical model, the equilibrium equation can be obtained:

[0058] P1A1+P3A3=P2A2 (1)

[0059] Here P2 should also include the pedal force. The pedal force F is relatively small and actually does not exceed 20N, so it is ignored in the above formula.

[0060] D = 2d;

[0061] D-diameter of piston A2, i.e. diameter of large chamber 3;

[0062] d-the diameter of piston A1, i.e. the diameter of small chamber 2;

[0063]

[0064] Substituting the calculated areas of A1, A2 and A3 into formula (1) yields:

[0065]

[0066] P1+3P3=4P2 (2)

[0067] from Figure 6 It can be seen that at this time, it is in the hydraulic transmission stage P1≈P3 (by Fig. 9 It can be seen that P1 and P3 are connected through a one-way valve, and the opening pressure of the one-way valve is very small (0.035MPa).

[0068] That is, equation (2) can be changed to 4P1=4P2, then P1=P2. This state means that when the oil tank port is sealed, there is oil pressure in the A3 chamber (small chamber 2), and this pressure is equal to the pressure of the oil pump.

[0069] The working process of the power-assist mode is as follows.

[0070] Figure 7 It means that when the piston 9 continues to move to the left, the conical sleeve 15 hits the head of the first one-way valve 7, but the first one-way valve 7 is not opened, it is still in the unassisted state. The theoretical mode is Figure 6 same.

[0071] like Figure 8 As shown, when the tapered sleeve 15 hits the first one-way valve 7 and pushes it open, the oil tank port 4 is connected to the large chamber 3 through the branch 6. At this time, P3=0, and the pressure of the brake left chamber oil P1>P3, so the second one-way valve 12 is closed.

[0072] At this time, the theoretical model is Fig. 9 When the piston 9 continues to move to the left, the pressurized liquid in the small chamber 2 is compressed and expanded, that is, it follows the following rule.

[0073] Liquid volume compressibility κ:

[0074]

[0075] κ—Liquid volume compressibility (m 2 / N);

[0076] K—Liquid bulk elastic modulus (N / m 2 );

[0077] V. — Initial volume of the enclosed volume (m 3 );

[0078] ΔV—Compression of the enclosed volume after being compressed (m 3 );

[0079] ΔP—Gauge pressure of the hydraulic oil in the sealed chamber after pressurization (N / m 2 );

[0080] Transform (3) into

[0081] Because Δp=P 液 -p. (5)

[0082] p. —Initial liquid pressure of the sealed chamber (N / m 2 ), the initial pressure is atmospheric pressure, that is, the gauge pressure is 0N / m 2 .

[0083] P 液 —The pressure after the sealed cavity expands is Fig. 9 P1(N / m 2 )

[0084] So Δp=P 液 -p. =P 液 -0=P 液 (6) Substituting (6) into (4) we get

[0085] The value of K is generally between (0.7-1.4)×10 3 MPa (See "Hydraulic Transmission", edited by Wang Jiwei from Southeast University, published by China Machinery Press, 2nd edition, January 2013, p11).

[0086] Assume K = 1.0 × 10 3 Mpa, the volume of the oil is compressed

[0087] but

[0088] This means that when the volume of the hydraulic oil is compressed by 1 / 100, the oil pressure in the closed volume can rise to 10Mpa.

[0089] D = 2d

[0090] Depend on Fig. 9 It can be seen that the force on the brake piston 9 should satisfy the equilibrium relationship P1A1=P2A2(8)

[0091]

[0092] P1=4P2 (9)

[0093] That is, the hydraulic pressure P1 on the brake disc is 4 times the oil supply pressure P2 of the oil pump, and there is a force amplification ratio relationship between them.

[0094] Fig.10 Indicated in Figure 8 On the basis of this, the reversing valve core 13 and the piston 9 move to the left under the combined action of the variable volume chamber and the pedal force, and the piston spring 30 is compressed to the limit position.

[0095] Fig.11It means that after the tractor is braked, the foot releases the pedal, and the reversing valve core 13 moves rightward under the action of the reversing spring 33, and returns to the initial relative position of the reversing valve core 13 and the piston 9. At this time, the space where the piston spring 30 is located, the first piston oil port 16, the valve core cavity, the first valve core oil port 25, the third valve core oil port 29 and the variable volume cavity are connected, and the third valve core sealing ring 27 passes over the third piston oil port 20 backward, disconnecting the third piston oil port 20 from the second valve core oil port 28, replenishing oil to the space where the piston spring 30 is located, and the variable volume cavity quickly releases pressure, and the piston spring 30 automatically pushes the piston 9 to the right to reset.

[0096] The piston spring 30 automatically pushes the piston 9 and the reversing valve core 13 to move rightward together and return to the initial state, completing the entire working cycle of the braking function. Figure 1 shown.

[0097] The power-assisted braking device of the present invention has an initial non-power-assisted braking mode and a later power-assisted braking mode through the arrangement of the piston 9, the reversing valve core 13, and each oil port, i.e., each sealing ring. The power-assisted braking mode is a subsequent mode of the non-power-assisted braking mode and is suitable for braking of large tractors.

[0098] The above embodiments are only exemplary embodiments of the present application and are not intended to limit the present application. The protection scope of the present application is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present application within the essence and protection scope of the present application, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present application.

Claims

1. A power-assisted braking device for braking, characterized in that: The invention comprises a cylinder body (1), wherein a small cavity (2) and a large cavity (3) which are interconnected and distributed along the axial direction are arranged in the cylinder body (1), wherein the diameter of the large cavity (3) is larger than the diameter of the small cavity (2), wherein the cylinder body (1) is respectively provided with a tank oil port (4) connected to the oil tank and a pump oil port (5) connected to the oil pump at positions corresponding to the large cavity (3), wherein a branch (6) connected to the large cavity (3) is also arranged on the side of the tank oil port (4) close to the small cavity (2), and a first one-way valve (7) which is unidirectionally connected to the tank oil port (4) is installed in the branch (6), and a brake oil port (8) connected to a brake actuator is arranged on the side of the cylinder body (1) away from the small cavity (2); A piston (9) is arranged in the cylinder body (1), a plug head (34) of the piston (9) is located in the small cavity (2), and an outer wall of the plug head (34) is arranged on a plug head (34) sealing ring, a front variable cavity (10) and a rear variable cavity (11) are respectively formed between the front and rear ends of the plug body (35) of the piston (9) and the cylinder body (1), a hole connecting the small cavity (2) and the front variable cavity (10) is arranged in the plug head (34), and a second one-way valve (12) that conducts one-way to the small cavity (2) is arranged in the hole; A reversing valve core (13) is arranged in the piston (9), and a valve core inner cavity (14) communicating with the rear variable cavity (11) is arranged at the center of the reversing valve core (13). Oil ports and sealing rings are arranged on the reversing valve core (13) and the piston (9). The reversing valve core (13) can move axially to control the communication between the rear variable cavity (11) and the oil pump oil port (5), so that the oil pump assists the movement of the piston (9) to provide braking assistance, or the communication between the rear variable cavity (11) and the oil tank oil port (4), so that the pressure oil in the rear variable cavity (11) flows back to the oil tank to release pressure; The piston (9) is capable of moving toward the front variable chamber (10) to block the connection between the oil tank port (4) and the front variable chamber (10), and to press the pressure oil in the front variable chamber (10) into the small chamber (2) to bring the brake pad closer to the brake disc; the plug body (35) is located at one end of the front variable chamber (10) and is externally sleeved with a conical sleeve (15) for pushing open the first one-way valve (7), so that when the braking force of the piston (9) reaches a maximum, the pressure oil in the front variable chamber (10) flows back to the oil tank through the first one-way valve (7).

2. A power-assisted braking device for braking according to claim 1, characterized in that: The outer edge of the piston (9) is provided with a first piston oil port (16), a first piston sealing ring (17), a second piston oil port (18), a second piston sealing ring (19), a third piston oil port (20) and a third piston sealing ring (21) in sequence in a direction away from the small cavity (2). Each piston sealing ring is mounted on a protruding ring (22) facing outward of the piston (9) and is in close contact with the inner wall of the cylinder body (1). Each piston oil port is used to connect the large cavity (3) with the inner cavity of the piston (9). The rear variable cavity (11) is formed between the third piston sealing ring (21) and the rear end of the cylinder body (1); A reversing valve core (13) capable of axial movement is arranged in the inner cavity of the piston (9); the end of the reversing valve core (13) away from the small cavity (2) passes through the rear end of the cylinder body (1) and is sealed with the cylinder body (1) through a fourth valve core sealing ring (23); a first valve core sealing ring (24), a first valve core oil port (25), a second valve core sealing ring (26), a third valve core sealing ring (27), a second valve core oil port (28) and a third valve core oil port (29) are arranged in sequence on the upper edge of the reversing valve core (13) in a direction away from the small cavity (2); the third valve core oil port (29) is connected to the rear variable cavity (11).

3. A power-assisted braking device for braking according to claim 1, characterized in that: A piston spring (30) is provided in the front variable cavity (10) and outside the piston (9); one end of the piston spring (30) is sleeved on the plug body (35), and the other end is sleeved on a positioning ring (31) extending toward the direction of the large cavity (3) from the separation surface of the large cavity (3) and the small cavity (2); and the conical sleeve (15) is displaced outside the piston spring (30); The positioning ring (31) is provided with a positioning ring oil port (32) for connecting the large cavity (3) and the small cavity (2); A reversing spring (33) is arranged between one end of the reversing valve core (13) close to the small chamber (2) and the piston (9).

4. A power-assisted braking device for braking according to claim 1, characterized in that: A plug neck (36) is also provided between the plug head (34) and the plug body (35); the diameter of the plug neck (36) is smaller than the diameter of the plug head (34) and the diameter of the small cavity (2); and a channel connecting the front variable cavity (10) and the small cavity (2) is provided on the plug neck (36).

5. The power-assisted braking device for braking according to claim 1, characterized in that: An exhaust port is arranged on the cylinder body (1) at a position corresponding to the small chamber (2), and an air vent plug (37) is installed in the exhaust port. The air vent plug (37) and the exhaust port are both stepped, and a sealing ring is arranged outside the end of the air vent plug (37) with a smaller diameter.

6. The power-assisted braking device for braking according to claim 1, characterized in that: The first one-way valve (7) comprises a valve core with its head extending into the large cavity (3), a compression spring located at the tail of the valve core, and a sealing valve stem threadedly connected to the cylinder body (1) for constraining the compression spring.

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