Multi-stage braking hydraulic control system and hydraulic control method thereof
By using a multi-stage braking hydraulic control system, combined with the control of the oil tank assembly, pump set, check valve, accumulator and multiple solenoid valves, the problem of excessive braking force during the lifting and lowering of heavy objects in the energy storage system is solved, and stable and safe braking of the equipment is achieved.
Patent Information
- Application Number
- CN202511137945.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-14
- Publication Date
- 2025-11-04
AI Technical Summary
In the power generation system of energy storage systems, excessive braking force during the lifting and transport of heavy objects can cause equipment slippage, and existing technologies make it difficult to achieve smooth braking.
The hydraulic control system employs multi-stage braking, achieving smooth braking through three-stage braking of the brakes. This includes the combined control of the oil tank assembly, pump group, check valve, accumulator, primary pressure reducing valve, multiple solenoid valves, and secondary pressure reducing valve.
Stable braking of the equipment has been achieved, meeting the braking requirements and ensuring the smoothness and safety of the equipment during multi-stage braking processes.
Smart Images
Figure CN120889787A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of hydraulic control, in particular to a multi-stage braking hydraulic control system and a hydraulic control method thereof. BACKGROUND
[0002] In the power generation system of the energy storage system, there is a need for braking in the lifting and carrying process of the heavy object. At present, the brake is often directly used for braking, which is easy to cause excessive braking force and make the equipment slip. Therefore, how to realize the function of stable braking through multi-stage braking has become a difficult problem to be solved at present. SUMMARY
[0003] The technical problem to be solved by the present application is to provide a multi-stage braking hydraulic control system and a hydraulic control method thereof, which has a simple structure, realizes the function of stable braking through three-stage braking of the brake, thereby ensuring the stability of the equipment and meeting the use requirements of braking.
[0004] To solve the above technical problems, the present application adopts the following technical scheme: a multi-stage braking hydraulic control system, the innovation of which lies in that it comprises an oil tank assembly, a pump group, a one-way valve, an accumulator, a first-stage pressure reducing valve, a brake electromagnetic valve I, a brake electromagnetic valve II, a brake electromagnetic valve III, a brake electromagnetic valve IV and a second electromagnetic valve; the first-stage pressure reducing valve is a three-way pressure reducing valve, the brake electromagnetic valve I and the brake electromagnetic valve II are both two-position four-way electromagnetic valves, and the brake electromagnetic valve III, the brake electromagnetic valve IV and the second electromagnetic valve are all normally open two-position two-way electromagnetic valves; the oil inlet end of the one-way valve is communicated with the oil tank assembly through the pump group, and the oil outlet end thereof is communicated with the accumulator and the oil inlet port P of the first-stage pressure reducing valve through pipelines; the working port A of the first-stage pressure reducing valve is communicated with the oil inlet port P of the brake electromagnetic valve I and the oil inlet port P of the brake electromagnetic valve II through pipelines, and the working port A of the brake electromagnetic valve I is communicated with one end of the brake electromagnetic valve III and one end of the second electromagnetic valve through pipelines, and the other end of the second electromagnetic valve is communicated with the oil port of a brake group I through a pipeline; the working port A of the brake electromagnetic valve II and one end of the brake electromagnetic valve IV are communicated with the oil port of a brake group II through pipelines, and the return oil port T of the brake electromagnetic valve I, the return oil port T of the brake electromagnetic valve II, the other end of the brake electromagnetic valve III, the other end of the brake electromagnetic valve IV and the return oil port T of the first-stage pressure reducing valve are communicated with the oil tank assembly through pipelines.
[0005] Preferably, the pump group can be selected from a gear pump group or a plunger pump group.
[0006] Preferably, a high-pressure filter is further arranged on the pipeline between the pump group and the one-way valve, and the high-pressure filter is used to filter the hydraulic oil pumped out by the pump group.
[0007] Preferably, the overflow valve is selected from a battery overflow valve or an electric proportional overflow valve, one end of which is communicated with the pipeline between the high-pressure filter and the one-way valve, and the other end is communicated with the oil tank assembly through a pipeline, thereby relieving pressure through the overflow valve.
[0008] Preferably, the first electromagnetic valve and the second pressure reducing valve are further included, the second pressure reducing valve is a three-way pressure reducing valve, and the first electromagnetic valve is a normally closed two-position two-way electromagnetic valve; the oil inlet P of the second pressure reducing valve is communicated with the working port A of the brake electromagnetic valve I through a pipeline, the working port A of the second pressure reducing valve is communicated with the oil port of the brake assembly I through a pipeline via the first electromagnetic valve, and the oil return port T of the second pressure reducing valve is communicated with the oil tank assembly through a pipeline.
[0009] Preferably, the working port B of the brake electromagnetic valve I and the working port B of the brake electromagnetic valve II are both sealed and plugged.
[0010] Preferably, the brake assembly I can be one brake, two brakes or multiple brakes, and the brake assembly II can be one brake, two brakes or multiple brakes.
[0011] The hydraulic control method of the multi-stage brake hydraulic control system, the innovation points of which are as follows: (1) primary brake (1.1) first, the brake electromagnetic valve I, the brake electromagnetic valve II, the brake electromagnetic valve III, the brake electromagnetic valve IV, the first electromagnetic valve and the second electromagnetic valve are powered on, at this time, the oil inlet P of the brake electromagnetic valve I is communicated with the working port A thereof, and the working port B thereof is communicated with the oil return port T thereof; the oil inlet P of the brake electromagnetic valve II is communicated with the working port A thereof, and the working port B thereof is communicated with the oil return port T thereof; the brake electromagnetic valve III, the brake electromagnetic valve IV and the second electromagnetic valve are all in the off state, and the first electromagnetic valve is in the closed state; (1.2) then, the pump group is started, the hydraulic oil in the oil tank assembly is pumped out, filtered through the high-pressure filter, and then flows to the oil inlet P of the accumulator and the primary pressure reducing valve, respectively; (1.3) then, the primary pressure reducing valve and the secondary pressure reducing valve are powered on, at this time, the oil inlet P of the primary pressure reducing valve is communicated with the working port A thereof, and the oil inlet P of the secondary pressure reducing valve is communicated with the working port A thereof; (1.4) at this time, the hydraulic oil at the oil inlet P of the primary pressure reducing valve flows to the oil inlet P of the brake electromagnetic valve I and the oil inlet P of the brake electromagnetic valve II through the working port A thereof, respectively; then, the oil inlet P of the brake electromagnetic valve I flows to the brake assembly I through the working port A thereof, the secondary pressure reducing valve and the first electromagnetic valve in sequence, and makes the brake assembly I in the half-braking state; at the same time, the oil inlet P of the brake electromagnetic valve II flows to the brake assembly II through the working port A thereof, and makes the brake assembly II open; (2) Second braking (2.1) First, the brake solenoid valve I, brake solenoid valve III, the first solenoid valve and the second solenoid valve are all de-energized, at this time the inlet P of brake solenoid valve I is communicated with its working port B, and its working port A is communicated with its return port T; brake solenoid valve III and the second solenoid valve are both in the closed state, and the first solenoid valve is in the open state; At the same time, brake solenoid valve II and brake solenoid valve IV are energized, at this time the inlet P of brake solenoid valve II is communicated with its working port A, and its working port B is communicated with its return port T; brake solenoid valve IV is in the open state; (2.2) Then the pump group starts, the hydraulic oil in the oil tank assembly is pumped out, filtered through the high-pressure filter, and then flows to the inlet P of the accumulator and the first pressure reducing valve, respectively; (2.3) Then the first pressure reducing valve is energized, at this time the inlet P of the first pressure reducing valve is communicated with its working port A; (2.4) At this time, the brake group I is affected by the spring, the hydraulic oil in it passes through the second solenoid valve, and then returns to the oil tank assembly through brake solenoid valve I and brake solenoid valve III, respectively, the brake group I is in the brake state, that is, the full braking state; At the same time, the inlet P of brake solenoid valve II flows to brake group II through its working port A, and brake group II is opened; (3) Third braking (3.1) First, the brake solenoid valve I, brake solenoid valve II, brake solenoid valve III, brake solenoid valve IV, the first solenoid valve and the second solenoid valve are all de-energized, at this time the inlet P of brake solenoid valve I is communicated with its working port B, and its working port A is communicated with its return port T; the inlet P of brake solenoid valve II is communicated with its working port B, and its working port A is communicated with its return port T; brake solenoid valve III, brake solenoid valve IV and the second solenoid valve are all in the closed state, and the first solenoid valve is in the open state; (3.2) Then the pump group starts, the hydraulic oil in the oil tank assembly is pumped out, filtered through the high-pressure filter, and then flows to the inlet P of the accumulator and the first pressure reducing valve, respectively; (3.3) Then the first pressure reducing valve is energized, at this time the inlet P of the first pressure reducing valve is communicated with its working port A; (3.4) At this time, the brake group I is affected by the spring, the hydraulic oil in it passes through the second solenoid valve, and then returns to the oil tank assembly through brake solenoid valve I and brake solenoid valve III, respectively, the brake group I is in the brake state, that is, the full braking state; At the same time, the brake group II is affected by the spring, the hydraulic oil in it returns to the oil tank assembly through brake solenoid valve II and brake solenoid valve IV, respectively, the brake group II is in the brake state, that is, the full braking state.
[0012] Preferably, when the hydraulic pressure is higher than a set value, the hydraulic oil is discharged back to the oil tank assembly through the overflow valve.
[0013] The present application has the advantages of simple structure, stable braking function realized by three-stage braking of the brake, stable equipment, and use requirement of braking. BRIEF DESCRIPTION OF DRAWINGS
[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative effort on the basis of these drawings.
[0015] Figure 1 A schematic diagram of a multi-stage braking hydraulic control system of the present application.
[0016] Among them, 1-oil tank assembly; 2-pump group; 3-high pressure filter; 4-overflow valve; 5-accumulator; 6-one-way valve; 7-first-stage pressure reducing valve; 8-brake solenoid valve I; 9-brake solenoid valve II; 10-brake solenoid valve III; 11-brake solenoid valve IV; 12-second-stage pressure reducing valve; 13-first solenoid valve; 14-second solenoid valve; 15-brake group I; 16-brake group II. DETAILED DESCRIPTION
[0017] The technical solutions of the present application will be described clearly and completely in the following specific embodiments.
[0018] A multi-stage braking hydraulic control system of the present application, comprising an oil tank assembly 1, a pump group 2, a one-way valve 6, an accumulator 5, a first-stage pressure reducing valve 7, a brake solenoid valve I 8, a brake solenoid valve II 9, a brake solenoid valve III 10, a brake solenoid valve IV 11, a first solenoid valve 13, a second solenoid valve 14, and a second-stage pressure reducing valve 12; the specific structure is shown in Figure 1 The first-stage pressure reducing valve 7 and the second-stage pressure reducing valve 12 are both three-way pressure reducing valves, the brake solenoid valve I 8 and the brake solenoid valve II 9 are both two-position four-way solenoid valves, the brake solenoid valve III 10, the brake solenoid valve IV 11, and the second solenoid valve 14 are all normally open two-position two-way solenoid valves, and the first solenoid valve 13 is a normally closed two-position two-way solenoid valve; the oil inlet end of the one-way valve 6 is communicated with the oil tank assembly 1 through the pump group 2, and the oil outlet end thereof is communicated with the accumulator 5 and the oil inlet port P of the first-stage pressure reducing valve 7 through pipelines respectively; As Figure 1As shown, the working port A of the primary pressure reducing valve 7 is communicated with the oil inlet port P of the brake electromagnetic valve I 8 and the oil inlet port P of the brake electromagnetic valve II 9 through pipes, respectively, and the working port A of the brake electromagnetic valve I 8 is communicated with the oil inlet port P of the secondary pressure reducing valve 12, one end of the brake electromagnetic valve III 10 and one end of the second electromagnetic valve 14 through pipes, respectively, and the working port A of the secondary pressure reducing valve 12 is communicated with one end of the first electromagnetic valve 13 through a pipe, and the other end of the first electromagnetic valve 13 and the other end of the second electromagnetic valve 14 are communicated with the oil port of the brake group I 15 through pipes, respectively; the working port A of the brake electromagnetic valve II 9 and one end of the brake electromagnetic valve IV 11 are communicated with the oil port of the brake group II 16 through pipes, respectively, and the oil return port T of the brake electromagnetic valve I 8, the oil return port T of the brake electromagnetic valve II 9, the other end of the brake electromagnetic valve III 10, the other end of the brake electromagnetic valve IV 11, the oil return port T of the primary pressure reducing valve 7 and the oil return port T of the secondary pressure reducing valve 12 are communicated with the oil tank assembly 1 through pipes. Among them, the pump group 2 can be selected from a gear pump group 2 or a plunger pump group 2, and the working port B of the brake electromagnetic valve I 8 and the working port B of the brake electromagnetic valve II 9 are sealed and blocked.
[0019] As shown in the figure, Figure 1 , a high-pressure filter 3 is further communicated on the pipe between the pump group 2 and the check valve 6, and the hydraulic oil pumped out by the pump group 2 is filtered through the high-pressure filter 3.
[0020] As shown in the figure, Figure 1 , the overflow valve 4 can be selected from a battery overflow valve 4 or an electric proportional overflow valve 4, and one end thereof is communicated with the pipe between the high-pressure filter 3 and the check valve 6, and the other end thereof is communicated with the oil tank assembly 1 through a pipe, thereby relieving pressure through the overflow valve 4.
[0021] As shown in the figure, Figure 1 , the brake group I 15 can be one brake, two brakes or multiple brakes, and the brake group II 16 can be one brake, two brakes or multiple brakes.
[0022] The hydraulic control method of the multi-stage braking hydraulic control system of the application, as shown in the figure, Figure 1 , comprises the following steps: (1) Primary braking (1.1) First, the brake electromagnetic valve I 8, the brake electromagnetic valve II 9, the brake electromagnetic valve III 10, the brake electromagnetic valve IV 11, the first electromagnetic valve 13 and the second electromagnetic valve 14 are powered on, at this time the oil inlet port P of the brake electromagnetic valve I 8 is communicated with the working port A thereof, and the working port B thereof is communicated with the oil return port T thereof; the oil inlet port P of the brake electromagnetic valve II 9 is communicated with the working port A thereof, and the working port B thereof is communicated with the oil return port T thereof; the brake electromagnetic valve III 10, the brake electromagnetic valve IV 11 and the second electromagnetic valve 14 are in the off state, and the first electromagnetic valve 13 is in the closed state.
[0023] (1.2) Then the pump group 2 starts, the hydraulic oil in the oil tank assembly 1 is pumped out, filtered through the high pressure filter 3, and then flows to the accumulator 5 and the inlet P of the primary pressure reducing valve 7 respectively.
[0024] (1.3) Then the primary pressure reducing valve 7 and the secondary pressure reducing valve 12 are powered on, at this time the inlet P of the primary pressure reducing valve 7 is communicated with the working port A, and the inlet P of the secondary pressure reducing valve 12 is communicated with the working port A.
[0025] (1.4) At this time, the hydraulic oil at the inlet P of the primary pressure reducing valve 7 flows to the inlet P of the brake solenoid valve I 8 and the inlet P of the brake solenoid valve II 9 through the working port A of the primary pressure reducing valve 7 respectively; then the inlet P of the brake solenoid valve I 8 flows to the brake group I 15 through the working port A, the secondary pressure reducing valve 12 and the first electromagnetic valve 13 in turn, and makes the brake group I 15 in the half brake state; at the same time, the inlet P of the brake solenoid valve II 9 flows to the brake group II 16 through the working port A, and makes the brake group II 16 open.
[0026] (2) Secondary brake (2.1) First, the brake solenoid valve I 8, the brake solenoid valve III 10, the first electromagnetic valve 13 and the second electromagnetic valve 14 are all powered off, at this time the inlet P of the brake solenoid valve I 8 is communicated with the working port B, and the working port A is communicated with the return port T; the brake solenoid valve III 10 and the second electromagnetic valve 14 are both in the closed state, and the first electromagnetic valve 13 is in the open state; At the same time, the brake solenoid valve II 9 and the brake solenoid valve IV 11 are powered on, at this time the inlet P of the brake solenoid valve II 9 is communicated with the working port A, and the working port B is communicated with the return port T; the brake solenoid valve IV 11 is in the open state.
[0027] (2.2) Then the pump group 2 starts, the hydraulic oil in the oil tank assembly 1 is pumped out, filtered through the high pressure filter 3, and then flows to the accumulator 5 and the inlet P of the primary pressure reducing valve 7 respectively.
[0028] (2.3) Then the primary pressure reducing valve 7 is powered on, at this time the inlet P of the primary pressure reducing valve 7 is communicated with the working port A.
[0029] (2.4) At this time, the brake group I 15 is affected by the spring, and the hydraulic oil in the brake group I 15 flows back to the oil tank assembly 1 through the second electromagnetic valve 14, the brake solenoid valve I 8 and the brake solenoid valve III 10 respectively, and the brake group I 15 is in the full brake state; At the same time, the inlet P of the brake solenoid valve II 9 flows to the brake group II 16 through the working port A, and makes the brake group II 16 open.
[0030] (3) Three-stage brake (3.1) First, brake solenoid valve I 8, brake solenoid valve II 9, brake solenoid valve III 10, brake solenoid valve IV 11, first solenoid valve 13 and second solenoid valve 14 are all de-energized, at this time the oil inlet P of brake solenoid valve I 8 is communicated with its working port B, and its working port A is communicated with its oil return port T; the oil inlet P of brake solenoid valve II 9 is communicated with its working port B, and its working port A is communicated with its oil return port T; brake solenoid valve III 10, brake solenoid valve IV 11 and second solenoid valve 14 are all in the closed state, and first solenoid valve 13 is in the open state.
[0031] (3.2) Then the pump group 2 starts, the hydraulic oil in the oil tank assembly 1 is pumped out, filtered through the high-pressure filter 3, and then flows to the accumulator 5 and the oil inlet P of the first-stage pressure reducing valve 7 respectively.
[0032] (3.3) Then the first-stage pressure reducing valve 7 is energized, at this time the oil inlet P of the first-stage pressure reducing valve 7 is communicated with its working port A.
[0033] (3.4) At this time, the brake group I 15 is acted on by the spring, the hydraulic oil in it flows back to the oil tank assembly 1 through the second solenoid valve 14, brake solenoid valve I 8 and brake solenoid valve III 10 respectively, the brake group I 15 is in the brake holding state, that is, the full braking state; At the same time, the brake group II 16 is acted on by the spring, the hydraulic oil in it flows back to the oil tank assembly 1 through brake solenoid valve II 9 and brake solenoid valve IV 11 respectively, the brake group II 16 is in the brake holding state, that is, the full braking state.
[0034] When the hydraulic pressure is higher than the set value, the hydraulic oil is discharged back to the oil tank assembly 1 through the overflow valve 4.
[0035] The beneficial effects of the present application are: the present application has simple structure, realizes the function of stable braking through three-stage braking of the brake, thereby ensuring the stability of the equipment, and meeting the use requirements of braking.
[0036] The above-described embodiments are only preferred embodiments of the present application, and do not limit the concept and scope of the present application, and various modifications and improvements to the technical solutions of the present application made by ordinary engineering technicians in the art without departing from the design concept of the present application shall fall within the protection scope of the present application, and the technical content claimed by the present application has been fully recorded in the technical requirements.
Claims
1. A multi-stage braking hydraulic control system, characterized in that: The system includes a fuel tank assembly, a pump unit, a check valve, an accumulator, a primary pressure reducing valve, brake solenoid valve I, brake solenoid valve II, brake solenoid valve III, brake solenoid valve IV, and a second solenoid valve. The primary pressure reducing valve is a three-way valve, and brake solenoid valves I and II are both two-position four-way solenoid valves. Brake solenoid valves III, IV, and the second solenoid valve are normally open two-position two-way solenoid valves. The inlet of the check valve is connected to the fuel tank assembly via the pump unit, and its outlet is connected via pipes to both the accumulator and the inlet P of the primary pressure reducing valve. The working port A of the primary pressure reducing valve is connected via pipes to the brake solenoid valve. The oil inlet P of brake solenoid valve I and the oil inlet P of brake solenoid valve II are connected. The working port A of brake solenoid valve I is connected to one end of brake solenoid valve III and one end of the second solenoid valve through a pipe. The other end of the second solenoid valve is connected to the oil port of brake assembly I through a pipe. The working port A of brake solenoid valve II and one end of brake solenoid valve IV are connected to the oil port of brake assembly II through pipes. The oil return port T of brake solenoid valve I, the oil return port T of brake solenoid valve II, the other end of brake solenoid valve III, the other end of brake solenoid valve IV, and the oil return port T of the first-stage pressure reducing valve are connected to the oil tank assembly through pipes.
2. The hydraulic control system for multi-stage braking according to claim 1, characterized in that: The pump set can be a gear pump set or a plunger pump set.
3. The multi-stage braking hydraulic control system according to claim 1, characterized in that: A high-pressure filter is also connected to the pipeline located between the pump unit and the check valve, and the hydraulic oil pumped out by the pump unit is filtered through the high-pressure filter.
4. The multi-stage braking hydraulic control system according to claim 3, characterized in that: It also includes an overflow valve; the overflow valve can be a battery overflow valve or an electro-proportional overflow valve, and one end of the valve is connected to the pipeline located between the high-pressure filter and the check valve, and the other end is connected to the oil tank assembly through a pipeline, thereby relieving pressure through the overflow valve.
5. A multi-stage braking hydraulic control system according to claim 4, characterized in that: It also includes a first solenoid valve and a second-stage pressure reducing valve; the second-stage pressure reducing valve is a three-way pressure reducing valve, and the first solenoid valve is a normally closed two-position two-way solenoid valve; the oil inlet P of the second-stage pressure reducing valve is connected to the working port A of the brake solenoid valve I through a pipeline, and the working port A of the second-stage pressure reducing valve is connected to the oil port of the brake assembly I through a pipeline via the first solenoid valve, and the oil return port T of the second-stage pressure reducing valve is connected to the oil tank assembly through a pipeline.
6. The hydraulic control system for multi-stage braking according to claim 1, characterized in that: Both the working port B of the brake solenoid valve I and the working port B of the brake solenoid valve II are sealed and plugged.
7. A multi-stage braking hydraulic control system according to claim 1, characterized in that: The brake group I can be one brake, two brakes or more brakes, and the brake group II can be one brake, two brakes or more brakes.
8. The hydraulic control method of a multi-stage braking hydraulic control system according to claim 5, characterized in that... Includes the following steps: (1) First-level braking (1.1) First, brake solenoid valve I, brake solenoid valve II, brake solenoid valve III, brake solenoid valve IV, first solenoid valve and second solenoid valve are all energized. At this time, the oil inlet P of brake solenoid valve I is connected to its working port A, and its working port B is connected to its return port T; the oil inlet P of brake solenoid valve II is connected to its working port A, and its working port B is connected to its return port T; brake solenoid valve III, brake solenoid valve IV and second solenoid valve are all in the open state, and the first solenoid valve is in the closed state. (1.2) Then the pump set starts and pumps out the hydraulic oil in the oil tank assembly. After being filtered by the high pressure filter, it flows to the accumulator and the oil inlet P of the first-stage pressure reducing valve respectively. (1.3) Then both the first-stage pressure reducing valve and the second-stage pressure reducing valve are energized. At this time, the oil inlet P of the first-stage pressure reducing valve is connected to its working port A, and the oil inlet P of the second-stage pressure reducing valve is connected to its working port A. (1.4) At this time, the hydraulic oil at the inlet P of the first-stage pressure reducing valve flows through its working port A to the inlet P of the brake solenoid valve I and the inlet P of the brake solenoid valve II respectively; then the inlet P of the brake solenoid valve I flows through its working port A, the second-stage pressure reducing valve and the first solenoid valve to the brake assembly I in sequence, and puts the brake assembly I in a semi-braking state; at the same time, the inlet P of the brake solenoid valve II flows through its working port A to the brake assembly II, and puts the brake assembly II open. (2) Secondary braking (2.1) First, brake solenoid valve I, brake solenoid valve III, first solenoid valve and second solenoid valve are all de-energized. At this time, the oil inlet P of brake solenoid valve I is connected to its working port B, and its working port A is connected to its return port T; brake solenoid valve III and second solenoid valve are both in the closed state, and first solenoid valve is in the open state. At the same time, both brake solenoid valve II and brake solenoid valve IV are energized. At this time, the oil inlet P of brake solenoid valve II is connected to its working port A, and its working port B is connected to its return port T; brake solenoid valve IV is in the off state. (2.2) Then the pump set starts and pumps out the hydraulic oil in the oil tank assembly. After being filtered by the high-pressure filter, it flows to the accumulator and the oil inlet P of the first-stage pressure reducing valve respectively. (2.3) Then the first-stage pressure reducing valve is energized, and at this time the oil inlet P of the first-stage pressure reducing valve is connected to its working port A; (2.4) At this time, the brake assembly I is under the action of the spring. The hydraulic oil in it passes through the second solenoid valve and then returns to the oil tank assembly through the brake solenoid valve I and the brake solenoid valve III respectively. The brake assembly I is in the holding brake state, that is, the full braking state. At the same time, the oil inlet P of the brake solenoid valve II flows to the brake assembly II through its working port A, and causes the brake assembly II to open. (3) Three-stage braking (3.1) First, brake solenoid valve I, brake solenoid valve II, brake solenoid valve III, brake solenoid valve IV, the first solenoid valve and the second solenoid valve are all de-energized. At this time, the oil inlet P of brake solenoid valve I is connected to its working port B, and its working port A is connected to its return port T; the oil inlet P of brake solenoid valve II is connected to its working port B, and its working port A is connected to its return port T; brake solenoid valve III, brake solenoid valve IV and the second solenoid valve are all in the closed state, and the first solenoid valve is in the open state. (3.2) Then the pump set starts and pumps out the hydraulic oil in the oil tank assembly. After being filtered by the high-pressure filter, it flows to the accumulator and the oil inlet P of the first-stage pressure reducing valve respectively. (3.3) Then the first-stage pressure reducing valve is energized, and at this time the oil inlet P of the first-stage pressure reducing valve is connected to its working port A; (3.4) At this time, the brake assembly I is under the action of the spring. The hydraulic oil in it passes through the second solenoid valve and then returns to the oil tank assembly through the brake solenoid valve I and the brake solenoid valve III respectively. The brake assembly I is in the holding brake state, that is, the full braking state. At the same time, under the action of the spring, the hydraulic oil in brake assembly II returns to the oil tank assembly through brake solenoid valve II and brake solenoid valve IV respectively, and brake assembly II is in the holding brake state, that is, the full braking state.
9. The hydraulic control method of a multi-stage braking hydraulic control system according to claim 8, characterized in that: When the hydraulic pressure is higher than the set value, the hydraulic oil is released back into the oil tank assembly through the relief valve.