Braking system, control method thereof, and crane

Abstract

The application discloses a brake system, a control method thereof and a crane, wherein an air outlet 1 of a foot brake valve is connected with a control port of a rear axle foot relay valve through a reversing switch 1, another air outlet of the reversing switch 1 is connected with a proportional electromagnetic valve group air inlet P; an air outlet 2 of the foot brake valve is connected with a control port of a front axle foot relay valve through a reversing switch 2, another air outlet of the reversing switch 2 is connected with the proportional electromagnetic valve group air inlet P; an air outlet A of a proportional electromagnetic valve 1 is connected with the control port of the front axle foot relay valve, and an air outlet A of a proportional electromagnetic valve 2 is connected with the control port of the rear axle foot relay valve; a brake control unit controls the opening degree of the proportional electromagnetic valve according to the detection values of a brake pedal angle sensor and a temperature sensor, so that the axle with a relatively lower temperature of the front axle and the rear axle obtains greater braking force. According to the application, the braking force of the front axle and the rear axle is distributed according to the temperature of the brake, the temperature rising difference of the brakes of the front axle and the rear axle can be effectively reduced, and the risk of the brake appearing heat recession can be reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to construction machinery, in particular to a brake system, a control method thereof and a crane. BACKGROUND

[0002] Heavy engineering vehicles, such as cranes, need to use the main brake for a long time when driving on long downhill sections or steep sections, which causes the brake temperature to rise rapidly, resulting in thermal recession phenomenon, and the braking capacity is significantly reduced, which seriously threatens the driving safety of the vehicle.

[0003] To improve the downhill braking performance of the vehicle, current vehicles are mostly equipped with retarders or engine auxiliary braking functions, wherein the retarders include hydraulic retarders, electric eddy current retarders, and the engine auxiliary braking includes engine exhaust braking, in-cylinder retardation and other auxiliary braking functions. The braking capacity of the hydraulic retarder is greatly affected by the engine speed, and when the speed is low, the braking effect is not ideal. The electric eddy current retarder is large in size and heavy in mass, which affects the economy of the vehicle, and the rotor temperature greatly affects the braking capacity. The exhaust braking is also greatly affected by the engine speed, and when the speed is low, the braking power is small and the braking effect is not ideal; when the speed is high, the initial braking speed is large and the braking effect is also not ideal. In addition, for vehicles with different front and rear axle braking forms, such as front disc and rear drum type vehicles, due to the influence of factors such as brake braking capacity and heat dissipation form, the temperature rise of the front and rear axle brakes is greatly different. In summary, for long downhill sections or steep sections, the auxiliary braking effect is not ideal. Therefore, the driver will frequently use the service brake system, and in this case, the thermal recession phenomenon is easy to occur, which significantly reduces the braking capacity of the vehicle.

[0004] CN113788407B discloses a control method, a controller and a crane for a crane, which uses a hydraulic drive system to provide braking force for the hydraulic drive axle in time, but cannot realize the distribution of different axle braking forces, and the thermal recession phenomenon is easy to occur on long downhill sections. SUMMARY

[0005] The purpose of the present application is to solve the problem that the auxiliary braking effect is not ideal when the current crane drives on long downhill sections or steep sections, and the driver frequently uses the service brake system, resulting in thermal recession phenomenon of the brake. The present application provides a brake system that can reasonably distribute the front and rear axle braking forces and reduce the risk of brake thermal recession phenomenon. The second purpose of the present application is to provide a control method of the brake system. The third purpose of the present application is to provide a crane comprising the brake system.

[0006] Technical solution: The brake system disclosed by the application comprises a foot brake valve, a reversing switch 1, a reversing switch 2, a front axle foot relay valve, a rear axle foot relay valve, an air reservoir 1, an air reservoir 2, a brake control unit, a proportional electromagnetic valve group, a temperature sensor, a brake pedal angle sensor and an auxiliary brake switch, the proportional electromagnetic valve group comprises a proportional electromagnetic valve 1 and a proportional electromagnetic valve 2, wherein the brake pedal angle sensor is used for detecting the brake pedal angle, and the temperature sensor is used for detecting the front and rear axle brake temperatures.

[0007] The air outlet 1 of the foot brake valve is connected to the control port of the rear axle foot relay valve through the reversing switch 1, the other air outlet of the reversing switch 1 is connected to the air inlet P of the proportional electromagnetic valve group, the air outlets of the rear axle foot relay valve are connected to the left and right service brake air chambers respectively, the air reservoir 1 is connected to the air inlet of the rear axle foot relay valve, and the rear axle service brake system is supplied with air.

[0008] The air outlet 2 of the foot brake valve is connected to the control port of the front axle foot relay valve through the reversing switch 2, the other air outlet of the reversing switch 2 is connected to the air inlet P of the proportional electromagnetic valve group, the air outlets of the front axle foot relay valve are connected to the left and right service brake air chambers respectively, the air reservoir 2 is connected to the air inlet of the front axle foot relay valve, and the front axle service brake system is supplied with air.

[0009] The air outlet A of the proportional electromagnetic valve 1 is connected to the control port of the front axle foot relay valve, and the air outlet A of the proportional electromagnetic valve 2 is connected to the control port of the rear axle foot relay valve.

[0010] The brake control unit is connected to the proportional electromagnetic valve group, the temperature sensor, the auxiliary brake switch and the brake pedal angle sensor, is used for controlling the opening degree of the proportional electromagnetic valve 1 and the proportional electromagnetic valve 2 according to the sensor detection value, and makes the axle with a relatively lower temperature of the front and rear axles obtain greater braking force.

[0011] Further, the proportional electromagnetic valve 1 and the proportional electromagnetic valve 2 are normally open proportional electromagnetic valves.

[0012] Further, the reversing switch 1 and the reversing switch 2 are replaced by normally open electromagnetic valves.

[0013] The control method of the brake system disclosed by the application comprises the following steps.

[0014] On a downhill section, the auxiliary brake switch is turned on, and the exhaust brake / retarder starts to act; meanwhile, the air outlets of the reversing switch 1 and the reversing switch 2 are switched to be connected to the air inlet P of the proportional electromagnetic valve group; when the vehicle speed is too large, the brake pedal is stepped on, and the brake control unit starts to work; at this time, the gas reaches the air inlet P of the normally open proportional electromagnetic valve group through the reversing switch 1 and the reversing switch 2 from the air outlet 1 and the air outlet 2 of the foot brake valve respectively.

[0015] The brake control unit calculates the brake force F of the system under the current brake pedal opening degree according to the detected brake pedal angle signal θ, and calculates the front and rear axle brake force distribution coefficients K1 and K2 in combination with the front and rear axle brake temperature signals, and transmits the electric signals to the normally open proportional electromagnetic valve group, and the proportional electromagnetic valve 1 and the proportional electromagnetic valve 2 adjust the valve opening degree according to the electric signals to control the size of the front and rear axle brake force, so that the axle with relatively lower temperature obtains greater brake force.

[0016] Further, the brake force F calculation formula is:

[0017] F=P(θ)·S

[0018] Wherein, P(θ) is the output port air pressure value when the brake pedal angle is θ, MPa; S is the air pressure action area, mm 2 .

[0019] Further, the front and rear axle brake force distribution coefficients K1 and K2 calculation formula is:

[0020]

[0021] Wherein, T1 is the front axle brake temperature, T2 is the rear axle brake temperature, ℃; T0 is the brake temperature threshold, ℃.

[0022] Further, during the braking process, when the brake control unit detects that the brake temperature is greater than the threshold T0, a prompt signal is sent to the driver to stop and cool down.

[0023] Further, when the brake control unit detects that the brake pedal is in the full braking state, the brake control unit does not participate in the work, at this time, the proportional electromagnetic valve 1 and the proportional electromagnetic valve 2 cannot be electrified, and are kept in the full opening state.

[0024] Further, all brake actions are ended when the accelerator pedal is stepped on or the auxiliary brake switch is turned off.

[0025] The crane comprises the brake system.

[0026] Beneficial effects: compared with the prior art, the present application has the following remarkable advantages: the present application distributes the front and rear axle brake force according to the brake temperature, so that the brake force is more reasonably distributed, and the temperature rise difference of the front and rear axle brakes can be effectively reduced, and the risk of brake heat recession is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the brake system provided by the embodiment of the present application;

[0028] Figure 2 It is a control method block diagram of the brake system provided by the embodiment of the present application. DETAILED DESCRIPTION

[0029] The application will be further described below with reference to the accompanying drawings.

[0030] As Figure 1 shown, a brake system provided by an embodiment of the application includes a foot brake valve, a reversing switch 1, a reversing switch 2, a front axle foot relay valve, a rear axle foot relay valve, an air reservoir 1, an air reservoir 2, a brake control unit, a proportional electromagnetic valve set, a temperature sensor a, a brake pedal angle sensor, and an auxiliary brake switch, the proportional electromagnetic valve set including a proportional electromagnetic valve 1 and a proportional electromagnetic valve 2; wherein the brake pedal angle sensor is configured to detect a brake pedal angle, and the temperature sensor a is configured to detect front and rear axle brake temperatures.

[0031] An outlet 1 (I port) of the foot brake valve is connected to a control port (4 port) of the rear axle foot relay valve through the reversing switch 1, another outlet (A2) of the reversing switch 1 is connected to a proportional electromagnetic valve set inlet P, an outlet (2 port) of the rear axle foot relay valve is connected to left and right service brake air chambers respectively, the air reservoir 1 is connected to an inlet (1 port) of the rear axle foot relay valve to supply air to a rear axle service brake system.

[0032] An outlet 2 (II port) of the foot brake valve is connected to a control port (4 port) of the front axle foot relay valve through the reversing switch 2, another outlet (A2) of the reversing switch 2 is also connected to the proportional electromagnetic valve set inlet P, an outlet (2 port) of the front axle foot relay valve is connected to left and right service brake air chambers respectively, the air reservoir 2 is connected to an inlet (1 port) of the front axle foot relay valve to supply air to a front axle service brake system.

[0033] An outlet A of the proportional electromagnetic valve 1 is connected to the control port (4 port) of the front axle foot relay valve, and an outlet A of the proportional electromagnetic valve 2 is connected to the control port (4 port) of the rear axle foot relay valve.

[0034] The brake control unit is connected to the proportional electromagnetic valve set, the temperature sensor a, the auxiliary brake switch, and the brake pedal angle sensor respectively, and is configured to control the opening degree of the proportional electromagnetic valve 1 and the proportional electromagnetic valve 2 according to the sensor detection values, so that the axle with a relatively lower temperature among the front and rear axles obtains a greater braking force.

[0035] Figure 1 The P port of the reversing switch is an inlet, the A1 port is an outlet 1, and the A2 port is an outlet 2.

[0036] In this embodiment, the proportional electromagnetic valve 1 and the proportional electromagnetic valve 2 are normally open proportional electromagnetic valves. The reversing switch 1 and the reversing switch 2 can be replaced by normally open electromagnetic valves, i.e., the normally open electromagnetic valves are directly arranged between the foot brake valve and the foot relay valve.

[0037] As Figure 2As shown, the embodiment of the application also provides a control method of the brake system described in the embodiment of the application, comprising:

[0038] After the vehicle enters the downhill section, the driver opens the auxiliary brake switch, the exhaust brake / retarder starts to act, and the vehicle travels at a constant speed or slows down; at the same time, the exhaust outlets of the reversing switch 1 and the reversing switch 2 are switched from A1 to A2 by A2; if the vehicle is in an accelerating state and the exhaust brake / retarder alone works unsatisfactorily due to a large slope of the section where the vehicle is located, the driver starts to step on the brake pedal to brake when the vehicle speed is too large, and the brake control unit starts to work; at this time, the gas reaches the inlet P of the normally open proportional electromagnetic valve group through the exhaust outlets A2 of the corresponding reversing switches from the I port and the II port of the foot brake valve respectively.

[0039] The brake control unit calculates the brake force F of the system at the current brake pedal opening degree according to the detected brake pedal angle signal θ, and calculates the front and rear axle brake force distribution coefficients K1 and K2 in combination with the front and rear axle brake temperature signals, and transmits the electrical signals to the normally open proportional electromagnetic valve group. At this time, the proportional electromagnetic valve 1 and the proportional electromagnetic valve 2 adjust the valve opening degree according to the electrical signals, so as to control the size of the front and rear axle brake force, and make the axle with relatively lower temperature obtain greater brake force.

[0040] Specifically, the brake force F calculation formula is:

[0041] F=P(θ)·S

[0042] Wherein, P(θ) is the output port gas pressure value when the brake pedal angle is θ, MPa; S is the gas pressure action area, mm 2 .

[0043] The front and rear axle brake force distribution coefficients K1 and K2 calculation formula is:

[0044]

[0045] Wherein, T1 is the front axle brake temperature, T2 is the rear axle brake temperature, ℃; T0 is the brake temperature threshold, ℃.

[0046] During the braking process, when the brake control unit detects that the brake temperature is greater than the threshold T0, a prompt signal is sent to the driver to stop and cool down.

[0047] When the brake control unit detects that the brake pedal is in a full braking state, the brake control unit does not participate in the work, and at this time the proportional electromagnetic valve 1 and the proportional electromagnetic valve 2 cannot be electrified and are kept in a fully open state.

[0048] All brake actions end when the accelerator pedal is stepped on or the auxiliary brake switch is turned off.

[0049] The embodiment of the application also provides a crane comprising the brake system.

[0050] In conclusion, the application adds a proportional electromagnetic control valve and other devices on the basis of the auxiliary brake scheme, feeds back temperature, auxiliary brake switch signals, brake pedal angle signals and other signals to the brake control unit, and gives real-time brake force to cooperate with the auxiliary brake.

Claims

1. A method for controlling a braking system, characterized in that: The braking system includes a foot brake valve, a reversing switch 1, a reversing switch 2, a front axle foot relay valve, a rear axle foot relay valve, an air reservoir 1, an air reservoir 2, a brake control unit, a proportional solenoid valve group, a temperature sensor, a brake pedal angle sensor, and an auxiliary brake switch. The proportional solenoid valve group includes proportional solenoid valve 1 and proportional solenoid valve 2. The brake pedal angle sensor is used to detect the brake pedal angle, and the temperature sensor is used to detect the temperature of the front and rear axle brakes. The air outlet 1 of the foot brake valve is connected to the control port of the rear axle foot relay valve via a reversing switch 1. The other air outlet of the reversing switch 1 is connected to the air inlet P of the proportional solenoid valve group. The air outlet of the rear axle foot relay valve is connected to the left and right service brake air chambers respectively. The air reservoir 1 is connected to the air inlet of the rear axle foot relay valve to supply air to the rear axle service brake system. The air outlet 2 of the foot brake valve is connected to the control port of the front axle foot relay valve via a reversing switch 2. The other air outlet of the reversing switch 2 is connected to the air inlet P of the proportional solenoid valve group. The air outlet of the front axle foot relay valve is connected to the left and right service brake air chambers respectively. The air reservoir 2 is connected to the air inlet of the front axle foot relay valve to supply air to the front axle service brake system. The air outlet A of the proportional solenoid valve 1 is connected to the control port of the relay valve of the front axle leg, and the air outlet A of the proportional solenoid valve 2 is connected to the control port of the relay valve of the rear axle leg; The brake control unit is connected to the proportional solenoid valve group, temperature sensor, auxiliary brake switch and brake pedal angle sensor respectively, and is used to control the opening of proportional solenoid valve 1 and proportional solenoid valve 2 according to the sensor detection value, so that the axle with relatively low temperature on the front and rear axles can obtain greater braking force; Proportional solenoid valve 1 and proportional solenoid valve 2 are normally open proportional solenoid valves; The control method of the braking system includes: On a downhill road, turn on the auxiliary brake switch, and the exhaust brake / retardation brake begins to operate. At the same time, the outlet ports of reversing switch 1 and reversing switch 2 are switched to connect with the inlet port P of the proportional solenoid valve group. When the vehicle speed is too high, step on the brake pedal, and the brake control unit starts to operate. At this time, the gas flows from the outlet ports 1 and 2 of the foot brake valve through reversing switch 1 and reversing switch 2 respectively to the inlet port P of the normally open proportional solenoid valve group. The brake control unit calculates the system's braking force F based on the detected brake pedal angle signal θ at the current brake pedal opening. It also calculates the front and rear axle braking force distribution coefficients K1 and K2 based on the front and rear axle brake temperature signals. These coefficients are then transmitted via electrical signals to the normally open proportional solenoid valve group. Proportional solenoid valves 1 and 2 adjust the valve openings based on the electrical signals to control the braking force on the front and rear axles, ensuring that the axle with the relatively lower temperature receives greater braking force. Calculation formula for front and rear axle braking force distribution coefficients K1 and K2: Wherein, T1 is the front axle brake temperature, T2 is the rear axle brake temperature, ℃; T0 is the brake temperature threshold, ℃.

2. The method for controlling a braking system according to claim 1, wherein: Braking force F calculation formula: F=P(θ)·S Where P(θ) is the output pressure value when the brake pedal angle is θ, MPa; S is the area where the pressure acts, mm 2 .

3. The control method of the braking system according to claim 1, characterized in that: During braking, when the brake control unit detects that the brake temperature is greater than the threshold value T0, it sends a prompt signal to the driver to stop the vehicle for cooling.

4. The method for controlling a braking system according to claim 1, wherein: When the brake control unit detects that the brake pedal is in full braking state, the brake control unit does not participate in the work. At this time, the proportional solenoid valve 1 and the proportional solenoid valve 2 are not energized and both remain in the fully open state.

5. The method for controlling a braking system according to any one of claims 1 to 4, characterized in that: All braking actions end when the accelerator pedal is depressed or the auxiliary brake switch is turned off.

6. The method for controlling a braking system according to claim 1, wherein: Reversing switch 1 and reversing switch 2 are replaced by normally open solenoid valves.

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