A safe hydraulic braking system, control method and electric concrete mixing truck

Abstract

The application discloses a safe hydraulic braking system, a control method and an electric concrete mixing and transporting vehicle, and belongs to the field of engineering machinery. The system comprises a power supply module, a hydraulic power unit, a brake, a hydraulic control valve, a motor controller and a control unit. The control unit judges based on the drive motor speed signal fed back by the motor controller: when the speed is zero, the hydraulic control valve is controlled to be closed, the brake executes braking on the output shaft of the drive motor under the action of the spring, and the mixing drum is locked; when the speed is not zero, the hydraulic control valve is controlled to be opened, and the hydraulic oil pressure overcomes the spring force to release the braking. The hydraulic power unit comprises a gear pump driven by a motor, an accumulator and a relief valve. The application solves the safety risk that the mixing drum loses control and rotates due to the offset of concrete when the electric mixer loses power or the drive fails through the automatic control logic triggered by the speed signal, and has the characteristics of rapid response, high reliability and failure safety.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery technology, specifically to a hydraulic braking system and control method for a concrete mixer truck. Furthermore, this invention particularly relates to a safety hydraulic braking system for an electric concrete mixer truck, used to prevent uncontrolled rotation of the mixing drum in the event of drive system failure, and a vehicle equipped with this system. Background Technology

[0002] Electric-powered new energy construction machinery is gradually replacing traditional fuel-powered equipment. Electric concrete mixer trucks, due to their advantages such as low noise, zero emissions, and high efficiency, have become an important development direction in the field of ready-mixed concrete transportation. Traditional concrete mixer trucks typically use hydraulic motors to drive the mixing drum. Their advantage lies in the fact that when the engine is off and the hydraulic pump stops supplying oil, the hydraulic system itself has a locking characteristic, which can, to a certain extent, prevent the mixing drum from rotating freely under the biased gravity of the concrete, thus providing a certain degree of safety.

[0003] However, the power transmission path of electric concrete mixer trucks differs fundamentally from that of traditional models. Their mixing drum is typically driven directly by a drive motor via a reducer. This drive method provides excellent maneuverability under normal operating conditions. However, a significant safety hazard exists: when the vehicle's high-voltage system experiences a power outage (e.g., emergency power failure, serious malfunction) or when the drive motor and its controller (motor controller) fail, the power connection and torque control between the drive motor and the mixing drum will completely fail. At this time, the biased gravitational torque generated by the uneven distribution of concrete within the mixing drum becomes the driving torque, causing the mixing drum (which drives the drive motor in the opposite direction via the reducer) to rotate freely. This uncontrolled rotation (which may be forward or reverse) is unpredictable and can easily cause the concrete inside the mixing drum to overflow due to violent agitation, or pose a serious risk of impact and crushing to surrounding personnel and equipment during vehicle loading and unloading operations, posing a significant safety threat.

[0004] While existing technologies have proposed adding auxiliary braking devices, designing an independent safety braking system that is deeply matched to the electrical and control characteristics of the electric mixer truck, operates reliably, responds quickly, and does not rely on the main drive power remains a technical problem that requires in-depth research and optimization in this field. In particular, a system is needed that can automatically and reliably intervene and implement braking the instant the drive motor completely fails (speed signal is zero) to fundamentally eliminate the risk of uncontrolled rotation of the mixing drum. Summary of the Invention

[0005] The technical problem to be solved by this invention is that, in view of the above-mentioned defects of the prior art, this application provides a safe hydraulic braking system for use in an electric concrete mixer truck, comprising:

[0006] The power supply module is used to provide the system with operating power.

[0007] The hydraulic power unit is electrically connected to the power supply module and is used to generate and regulate hydraulic pressure under the drive of electric power.

[0008] The brake, connected to the hydraulic power unit via an oil circuit, is used to brake or release the output shaft of the drive motor on the electric concrete mixer truck according to the state of the system oil pressure. The drive motor is used to drive the mixing drum to rotate.

[0009] A hydraulic control valve is connected between the hydraulic power unit and the oil port of the brake.

[0010] The motor controller is electrically connected to the power supply module and the drive motor, and is used to control the operation of the drive motor and acquire its status signals;

[0011] The control unit is connected to both the motor controller and the hydraulic control valve, and makes the following judgments based on the drive motor speed signal obtained from the motor controller:

[0012] When it is determined that the speed of the drive motor is zero, the hydraulic control valve is controlled to cut off the hydraulic oil circuit to the brake, so that the brake performs braking.

[0013] When it is determined that the speed of the drive motor is not zero, the hydraulic control valve is opened, so that the hydraulic pressure provided by the hydraulic power unit acts on the brake to release the brake.

[0014] Preferably, the brake is a normally closed spring-hydraulic brake, including a brake housing, a brake piston disposed within the brake housing, a spring that applies force to the brake piston, and a locking rod connected to the brake piston; wherein, the spring force drives the locking rod to extend to achieve braking; the hydraulic pressure is used to drive the brake piston to overcome the spring force to retract the locking rod, thereby releasing the brake.

[0015] Preferably, a brake disc is coaxially mounted on the output shaft of the drive motor; a brake pad is provided at the end of the locking rod opposite to the brake disc; when the control unit controls the hydraulic control valve to close, the spring pushes the brake piston and the locking rod, causing the brake pad to press against the end face or circumferential surface of the brake disc, achieving braking through friction; when the hydraulic control valve opens and the system oil pressure is established, the hydraulic pressure drives the brake piston to compress the spring and drive the locking rod to retract, creating a gap between the brake pad and the brake disc, thus releasing the brake.

[0016] Preferably, the hydraulic control valve is a hydraulic solenoid directional valve.

[0017] Preferably, the hydraulic power unit includes a motor, a gear pump driven by the motor, a hydraulic oil tank, and a check valve connected to the output oil line of the gear pump; the oil inlet of the gear pump is connected to the hydraulic oil tank, and the oil outlet is connected to the hydraulic control valve after passing through the check valve.

[0018] Preferably, the hydraulic power unit further includes an accumulator and a relief valve; the accumulator is connected to the pipeline between the check valve and the hydraulic control valve; the inlet of the relief valve is connected to the pipeline between the outlet of the gear pump and the check valve, and the outlet is connected back to the hydraulic oil tank.

[0019] Preferably, the power supply module includes a high-voltage energy storage battery for the vehicle and a DC-DC converter; the output of the high-voltage energy storage battery is connected to the input terminals of the motor controller and the DC-DC converter, respectively; the output terminal of the DC-DC converter supplies power to the hydraulic power unit.

[0020] This application also provides a safe hydraulic braking method for an electric concrete mixer truck, using the aforementioned safe hydraulic braking system, the method comprising:

[0021] Status monitoring steps: The control unit obtains the speed signal of the drive motor in real time through the motor controller;

[0022] Braking judgment and execution steps: When the control unit determines that the speed of the drive motor is zero, it controls the hydraulic control valve to close, cuts off the hydraulic oil circuit to the brake, and causes the brake to perform braking on the drive component under the action of the spring;

[0023] Brake release procedure: When the control unit determines that the speed of the drive motor is not zero, it controls the hydraulic control valve to open, so that the pressure oil provided by the hydraulic power unit enters the brake to overcome the spring force and release the brake.

[0024] This application also provides an electric concrete mixer truck with a safe hydraulic braking system, comprising:

[0025] Vehicle body;

[0026] A mixing drum is installed on the vehicle body;

[0027] A drive motor is used to drive the stirring drum to rotate;

[0028] A speed reducer is connected between the drive motor and the stirring drum;

[0029] As described in the safety hydraulic braking system, the brake is connected to the output shaft of the drive motor for braking.

[0030] The advantages of the technical solution provided in this application compared with the prior art are mainly reflected in the following aspects:

[0031] 1. Intrinsically safe and highly reliable: The system uses the real-time speed of the drive motor as the core of braking judgment and adopts a "normally closed" brake and "power failure braking" hydraulic control logic to ensure that the system can automatically and reliably perform braking at the moment of power interruption for any reason, fundamentally preventing the mixing drum from going out of control.

[0032] 2. Optimized power supply scheme with strong reliability: It creatively utilizes the vehicle's high-voltage energy storage battery to power the independent braking system, avoiding the risk of insufficient power that may result from mixing with the vehicle's low-voltage circuit, and ensuring the reliability of the braking system from the energy source.

[0033] 3. Rapid response and high energy efficiency: By pre-storing pressure in the accumulator, millisecond-level switching of braking states can be achieved. The intelligent pressure closed-loop control logic only activates pressure replenishment when needed, reducing component wear and unnecessary energy consumption.

[0034] 4. High system integration: The braking control logic can be seamlessly integrated into the vehicle's existing controller (VCU) without the need for an additional independent controller, which simplifies the system structure and improves overall reliability. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the safety hydraulic braking system in an electric mixer truck according to Embodiment 1 of the present invention.

[0036] Figure 2 This is a schematic diagram of a hydraulic braking system according to one embodiment of the brake of the present invention.

[0037] Figure 3 This is a flowchart of the pressure adaptive control process of the hydraulic power unit of the present invention.

[0038] Figure 4 This is a safety braking logic diagram of the control unit of the present invention based on the state of the drive motor.

[0039] Explanation of the labels in the diagram:

[0040] 1-Drive motor; 2-Agitator; 3-Brake; 31-Brake housing; 32-Brake piston; 33-Spring; 34-Locking rod; 4-Power supply module; 5-Hydraulic control valve; 6-Motor controller; 7-Control unit; 8-Motor; 9-Gear pump; 10-Hydraulic oil tank; 11-Check valve; 12-Accumulator; 13-Relief valve; 14-High-voltage energy storage battery; 15-DC-CDC converter; 16-Reducer; 17-Pressure sensor; 18-Filter. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the following embodiments are only for explaining the invention and not for limiting it. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0042] Example 1

[0043] This embodiment provides a complete safe hydraulic braking system and its application in an electric concrete mixer truck. The system principle can be found in [reference needed]. Figures 1-4 .

[0044] System overall structure and connection relationship

[0045] The electric concrete mixer truck of this embodiment includes a vehicle body, a mixing drum 2, a drive motor 1, a reducer 16, and the safety hydraulic braking system of the present invention. The output shaft of the drive motor 1 is connected to the rotating mechanism of the mixing drum 2 through the reducer 16, providing it with rotational power. The safety hydraulic braking system mainly includes the following parts:

[0046] Power supply module 4: such as Figure 1 As shown, this embodiment preferably uses an on-board power supply. It includes the vehicle's existing high-voltage energy storage battery 14 and a DC-DC converter 15. The output of the high-voltage energy storage battery 14 (such as a 300V or higher power battery) is divided into two paths: one directly supplies the motor controller 6 to drive the main drive motor 1; the other is connected to the input of the DC-DC converter 15. The DC-DC converter 15 converts the high-voltage DC power into a stable low-voltage DC power (such as 24VDC), which serves as the control and power source for the entire braking system.

[0047] Hydraulic power unit: See Figure 1 and Figure 2 The system includes a motor 8, a gear pump 9, a hydraulic oil tank 10, a check valve 11, an accumulator 12, a relief valve 13, and a pressure sensor 17 (whose signal is connected to the control unit 7). The motor 8 (i.e., the accumulator motor) is driven by a 24V power supply from a DC-DC converter 15. The output shaft of the motor 8 is coaxially connected to the gear pump 9, driving its rotation. The inlet of the gear pump 9 is connected to the hydraulic oil tank 10 through a filter screen, and its outlet pipeline is divided into two paths: one path leads to the system pressure pipeline (port P) via the check valve 11; the other path connects to the inlet of the relief valve 13. The outlet of the relief valve 13 returns to the hydraulic oil tank 10. The accumulator 12 is connected via a branch to the system pressure pipeline after the outlet of the check valve 11. The pressure sensor 17 is installed on this pressure pipeline for real-time monitoring of system pressure. The system pressure pipeline is ultimately connected to the inlet P of the hydraulic control valve 5.

[0048] Brake 3: This embodiment uses a normally closed multi-disc spring hydraulic brake. Brake 3 is fixedly mounted on the non-output end cover of drive motor 1 via a flange. A brake disc is coaxially mounted on the output shaft extension of drive motor 1. Brake 3 internally includes a brake housing, a brake piston, a disc spring assembly, and a locking rod linked to the brake piston. A brake pad is attached to the end of the locking rod. When there is no hydraulic pressure, the preload of the disc spring assembly pushes the brake piston, causing the brake pad to press against the end face of the brake disc, generating a huge braking torque that locks the output shaft; this is the braking state. When hydraulic oil enters from the oil port of brake 3, and the thrust generated by the oil pressure is sufficient to overcome the spring preload, the brake piston is pushed back, causing the brake pad to separate from the brake disc, forming a gap; this is the release state. The oil port of brake 3 is connected to the working oil port of hydraulic control valve 5 via an oil pipe.

[0049] Hydraulic control valve 5: This embodiment uses a two-position three-way (normally closed) hydraulic solenoid directional valve. Its inlet port P is connected to the system pressure pipeline of the hydraulic power unit, the working port A is connected to the oil port of the brake 3, and the return port T is connected back to the hydraulic oil tank 10. When its solenoid is not energized, the valve core is in the closed position under the action of the spring, the P port and the A port are not connected, and the A port and the T port are connected (the brake is depressurized). When its solenoid is energized, the valve core reverses, the P port and the A port are connected, the pressurized oil enters the brake, and at the same time the A port and the T port are disconnected.

[0050] Motor controller 6 and control unit 7: Motor controller 6 is electrically connected to high-voltage energy storage battery 14 and drive motor 1, and is responsible for the vector control of drive motor 1. Control unit 7 can be the vehicle's existing vehicle control unit (VCU). Control unit 7 communicates with motor controller 6 via CAN bus to obtain the precise speed signal of drive motor 1 in real time. At the same time, control unit 7 receives the signal from pressure sensor 17 and outputs control commands to control the energization and de-energization of the electromagnet of hydraulic control valve 5 and motor 8 in hydraulic power unit, respectively. Power supply for control unit 7 is provided by DC-DC converter 15.

[0051] Pressure closed-loop control of the hydraulic power unit (accumulator motor control logic)

[0052] See attached Figure 3 The control unit 7 implements intelligent closed-loop pressure control of the hydraulic power unit, which is crucial for ensuring rapid braking response and high system efficiency and energy saving. Its core control logic focuses on maintaining the pressure within the accumulator 12 within a preset optimal operating range.

[0053] The control unit 7 has a preset upper limit and a lower limit for the target pressure (e.g., an upper limit of 10 MPa and a lower limit of 8 MPa). During system operation, the control unit 7 continuously reads the feedback value (i.e., "sensor pressure") from the pressure sensor 17 and controls the start and stop of the motor 8 (accumulator motor) cyclically according to the following logic:

[0054] Low-pressure compensation trigger: Control unit 7 first determines whether the current sensor pressure is less than or equal to the preset target lower pressure limit. When the result is "yes", it indicates that the accumulator 12 pressure is insufficient, which may affect the rapid release of the brake. At this time, control unit 7 immediately sends a start command to motor 8. Motor 8 drives gear pump 9 to draw oil from hydraulic oil tank 10, and the oil is filtered by filter 18 on the oil suction line. The output pressure oil opens check valve 11, filling the accumulator 12 and system pipelines with fluid, rapidly increasing the system pressure.

[0055] High-pressure protection shutdown: Control unit 7 continuously monitors the pressure. When the sensor pressure reaches or exceeds the preset target pressure limit, it indicates that the accumulator 12 is fully charged and the pressure is sufficient. At this time, control unit 7 cuts off the power supply to motor 8, causing it to stop, gear pump 9 stops working, and the system enters the pressure-holding state.

[0056] Pressure Holding and Circulation: During pressure holding, the pressure will slowly decrease due to minor internal leakage in the hydraulic system. Once the pressure drops to the lower limit again, the control unit 7 will restart the motor 8 to replenish the pressure. This "intermittent oiling" mode ensures that the system pressure is always maintained within the usable range, while minimizing unnecessary operation of the motor 8, achieving energy saving and extending component life. The relief valve 13 is set at a pressure slightly higher than the target pressure limit (e.g., 12 MPa) as a final safety valve to prevent accidental overpressure in the system.

[0057] System overall workflow and safety braking trigger

[0058] Reference Appendix Figure 4 Based on the pressure control described above, the overall operation and safety braking process of the system is as follows:

[0059] System initialization and pressure establishment: After the vehicle is powered on, the control unit 7 performs a self-check. Then, the control unit 7 first activates the aforementioned pressure closed-loop control logic, controlling the motor 8 to operate and pressurize the accumulator 12 until the system pressure reaches the preset operating range. Afterward, the control unit 7 energizes the electromagnet of the hydraulic control valve 5, allowing the pressurized oil in the accumulator 12 to enter the brake 3 through the hydraulic control valve 5, overcoming the spring force and releasing the brake. At this time, the output shaft of the drive motor 1 is in a freely rotating state.

[0060] Normal Operation (Controlled Rotation of the Mixing Drum): With the brake released, the operator controls the motor controller 6 via the operating device, causing the drive motor 1 to rotate. This rotation, through the reducer 16, drives the mixing drum 2 to perform the operation. During this period, the control unit 7 continuously reads the speed signal of the drive motor 1 from the motor controller 6. As long as the speed is not zero (i.e., greater than a near-zero threshold, such as >10 rpm), the control unit 7 keeps the hydraulic control valve 5 open, thereby ensuring that the brake 3 is released. Simultaneously, the pressure closed-loop control logic runs independently in the background to maintain system pressure.

[0061] Fail-safe braking (core protection scenario): When an emergency power outage, high-voltage system failure, or drive system failure occurs, causing the speed of drive motor 1 to drop to zero, the safety logic of control unit 7 is immediately triggered. Control unit 7 sends a "power-off" command to the electromagnet of hydraulic control valve 5. Hydraulic control valve 5 resets to the closed position under the action of its internal spring, cutting off the pressure oil circuit and connecting the oil chamber of brake 3 to the oil tank to relieve pressure. The preload of the disc spring assembly inside brake 3 is quickly released, pushing the brake piston, causing the brake pads to press tightly against the brake disc, generating a huge frictional braking torque, which firmly locks the output shaft of drive motor 1 and the indirectly connected stirring drum 2, preventing them from rotating freely. This process is completely automatic and does not rely on the main drive electric system, achieving intrinsic safety. Even if the motor 8 of the hydraulic power unit stops due to power failure at this time, the pressure oil stored in accumulator 12 is sufficient to support the pressure holding requirement after this brake release, or the system pressure established before the power failure can be directly used to trigger this brake.

[0062] Resumption of operation: When the fault is resolved and a restart is required, the control unit 7 will first ensure that the system pressure is normal, then open the hydraulic control valve 5 to release the brake, and finally allow the drive motor 1 to start.

[0063] Technical advantages of this embodiment

[0064] 1. Dual safety triggering: The system uses the zero speed of the drive motor as the main braking trigger signal, resulting in a direct and rapid response. Simultaneously, the hydraulic system employs a normally closed brake and a directional valve that closes upon power failure, conforming to the "fail-safe" principle.

[0065] 2. Rapid Response and Energy Saving: Independent closed-loop pressure control of the accumulator ensures instantaneous supply of pressurized oil during brake release, achieving millisecond-level response. The intermittent pressure maintenance strategy greatly reduces energy consumption and component wear.

[0066] 3. High integration and reliability: Fully utilizes the vehicle's high-voltage power supply, powered by a DC-DC converter, resulting in strong system independence. The control logic is integrated into the vehicle's VCU, eliminating the need for an additional controller, thus achieving excellent cost-effectiveness and reliability.

[0067] Example 2

[0068] This embodiment provides another implementation method, the main difference from Embodiment 1 being the power supply scheme. In this embodiment, the power supply module 4 of the safety hydraulic braking system does not rely on the vehicle's high-voltage storage battery 14. Instead, it uses an independent, external power supply system, such as an independent 24V battery pack. This external power supply directly powers the motor 8 of the hydraulic power unit, the electromagnet of the hydraulic control valve 5, and the control unit 7. The motor controller 6 is still powered by the vehicle's high-voltage storage battery 14.

[0069] The advantage of this embodiment is that the power supply of the braking system is completely physically isolated from the vehicle's main drive system. Even if a serious fault occurs in the vehicle's high-voltage system, causing a complete power outage, the independent external power supply can still ensure the normal operation of the safety hydraulic braking system and trigger braking action, providing a higher level of safety. Its system composition, working principle, and control logic are exactly the same as those in Embodiment 1.

[0070] Example 3

[0071] This embodiment provides a variation in the mounting position of the brake 3. In the above embodiment, the brake 3 acts directly on the output shaft of the drive motor 1. In this embodiment, the brake 3 can also be mounted on other rotating components that have a fixed transmission ratio with the stirring drum 2 to achieve the same braking purpose. For example:

[0072] Install brake 3 on the input or output shaft of reducer 16.

[0073] Alternatively, in vehicles that use a tow wheel to drive the mixing drum, the brake 3 is mounted on the tow wheel axle that drives the mixing drum to rotate.

[0074] The principle of this embodiment is that as long as the brake 3 can lock a rotating component that is rigidly or transmissionally connected to the mixing drum 2, it can ultimately prevent the mixing drum 2 from rotating. Its control logic remains unchanged. This provides a flexible and safe braking solution for electric mixer trucks with different structural forms.

[0075] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. The present invention and its embodiments have been described above, and this description is not restrictive. The figures shown are only one embodiment of the present invention, and the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structural methods and embodiments without departing from the inventive spirit of the present invention, they should all fall within the scope of protection of the present invention.

Claims

1. A safe hydraulic braking system applied to an electric concrete mixer truck, characterized in that, include: Power supply module (4) is used to provide working power to the system; The hydraulic power unit is electrically connected to the power supply module (4) and is used to generate and regulate hydraulic pressure under the drive of electric energy; The brake (3) is connected to the hydraulic power unit through an oil circuit and is used to brake or release the output shaft of the drive motor (1) on the electric concrete mixer truck according to the state of the system oil pressure. The drive motor (1) is used to drive the mixing drum (2) to rotate. A hydraulic control valve (5) is connected between the hydraulic power unit and the oil port of the brake (3); The motor controller (6) is electrically connected to the power supply module (4) and the drive motor (1) and is used to control the operation of the drive motor (1) and acquire its status signal; The control unit (7) is connected to the motor controller (6) and the hydraulic control valve (5) respectively, and makes the following judgment based on the speed signal of the drive motor (1) obtained from the motor controller (6): When it is determined that the speed of the drive motor (1) is zero, the hydraulic control valve (5) is controlled to cut off the hydraulic oil circuit to the brake (3), so that the brake (3) performs braking. When it is determined that the speed of the drive motor (1) is not zero, the hydraulic control valve (5) is opened so that the hydraulic pressure provided by the hydraulic power unit acts on the brake (3) to release the brake.

2. The safe hydraulic braking system according to claim 1, characterized in that, The brake (3) is a normally closed spring hydraulic brake, including a brake housing (31), a brake piston (32) disposed in the brake housing (31), a spring (33) that applies force to the brake piston (32), and a locking rod (33) connected to the brake piston (32); wherein, the elastic force of the spring (33) drives the locking rod (33) to extend to achieve braking; the hydraulic pressure is used to drive the brake piston (32) to overcome the elastic force of the spring (33) to retract the locking rod (33), thereby releasing the brake.

3. The safe hydraulic braking system according to claim 2, characterized in that, A brake disc is coaxially mounted on the output shaft of the drive motor (1); a brake pad is provided at the end of the locking rod (33) opposite to the brake disc; when the control unit (7) controls the hydraulic control valve (5) to close, the spring (33) pushes the brake piston (32) and the locking rod (33) to press the brake pad against the end face or circumferential surface of the brake disc, and braking is achieved through friction; when the hydraulic control valve (5) is opened and the system oil pressure is established, the hydraulic pressure drives the brake piston (32) to compress the spring (33) and drive the locking rod (33) to retract, so that a gap is formed between the brake pad and the brake disc, and the braking is released.

4. The safe hydraulic braking system according to claim 1, characterized in that, The hydraulic control valve (5) is a hydraulic solenoid directional valve.

5. The safe hydraulic braking system according to claim 1, characterized in that, The hydraulic power unit includes a motor (8), a gear pump (9) driven by the motor (8), a hydraulic oil tank (10), and a check valve (11) connected to the output oil line of the gear pump (9); the oil inlet of the gear pump (9) is connected to the hydraulic oil tank (10), and the oil outlet is connected to the hydraulic control valve (5) after passing through the check valve (11).

6. The safe hydraulic braking system according to claim 5, characterized in that, The hydraulic power unit also includes an accumulator (12) and an overflow valve (13); the accumulator (12) is connected to the pipeline between the check valve (11) and the hydraulic control valve (5); the inlet of the overflow valve (13) is connected to the pipeline between the outlet of the gear pump (9) and the check valve (11), and the outlet is connected back to the hydraulic oil tank (10).

7. The safe hydraulic braking system according to claim 1, characterized in that, The power supply module (4) includes a high-voltage energy storage battery (14) and a DC-DC converter (15) for the vehicle; the output of the high-voltage energy storage battery (14) is connected to the input terminals of the motor controller (6) and the DC-DC converter (15); the output terminal of the DC-DC converter (15) supplies power to the hydraulic power unit.

8. A safe hydraulic braking method for an electric concrete mixer truck, characterized in that, The method of using a safe hydraulic braking system as described in any one of claims 1-7 comprises: Status monitoring steps: The control unit (7) obtains the speed signal of the drive motor (1) in real time through the motor controller (6); Braking judgment and execution steps: When the control unit (7) judges that the speed of the drive motor (1) is zero, it controls the hydraulic control valve (5) to close, cuts off the hydraulic oil circuit to the brake (3), and makes the brake (3) brake the drive component under the action of the spring; Brake release step: When the control unit (7) determines that the speed of the drive motor (1) is not zero, it controls the hydraulic control valve (5) to open, so that the pressure oil provided by the hydraulic power unit enters the brake (3) to overcome the spring force and release the brake.

9. An electric concrete mixer truck with a safe hydraulic braking system, characterized in that, include: Vehicle body; A mixing drum (2) is installed on the vehicle body; A drive motor (1) is used to drive the stirring drum (2) to rotate; A speed reducer (16) is connected between the drive motor (1) and the stirring drum (2); The safety hydraulic braking system according to any one of claims 1-7, wherein the brake (3) is connected to the output shaft of the drive motor (1) for braking it.

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