Brake compensation control method and system and crane with system

Abstract

The invention discloses a brake compensation control method and system and a crane with the system.According to the brake compensation control method, calibration is carried out according to different axle load states and tire sizes of a real vehicle, and under the conditions that a service brake system is intact, a brake loop fails, brake is abraded and the auxiliary brake capacity is insufficient, the brake compensation control system is calibrated according to the different axle load states and the tire sizes of the real vehicle. Braking compensation strategies are given respectively, so that the braking capacity of the service braking system and the braking capacity of the auxiliary braking system can be better coordinated and controlled, the burden of the service braking system is relieved, the stability of the braking capacity of the whole vehicle is maintained, and the braking safety of the whole vehicle is improved; for a vehicle provided with an anti-lock braking system, deceleration is introduced as a braking system performance index, a compensation strategy is optimized, and the auxiliary braking gear intervening in compensation is controlled more accurately. And for the vehicle provided with the EBS, the braking torque output proportion under the same pedal stroke is adjusted, and when the auxiliary braking capacity is insufficient or an auxiliary braking device breaks down, the service braking capacity is compensated.

Description

Technical Field

[0001] The invention relates to brake control, and in particular to a brake compensation control method and system and a crane having the system. Background Art

[0002] With the development of the construction machinery industry, the travel speed and load capacity of cranes have been greatly improved, which means that the performance of the braking system needs to be safer and more reliable. During driving, the service brake is generally used to slow down or stop the vehicle. The service brake system needs to bear a large amount of heat load. Frequent or long-term braking will cause the temperature of the brake device to rise sharply and the braking capacity will be greatly reduced. If there is a circuit failure or severe wear of the brake lining in the service brake system, its braking capacity will be greatly reduced, endangering driving safety.

[0003] The industry generally uses the braking torque generated by the auxiliary braking system on the vehicle to reduce the vehicle speed, compensate the service braking system, and reduce the burden on the brakes, but the control method is single, and only controls the opening of auxiliary braking at different gears according to the specific brake pedal stroke. Although it has shared the pressure of the service braking system to a certain extent, for vehicles with different axle loads and tire sizes, the same braking compensation strategy often cannot accurately distribute the braking torque. If the degree of auxiliary braking intervention is too low, the ideal braking capacity cannot be achieved, the vehicle braking force is insufficient, and the emergency braking distance is long; if the degree of auxiliary braking intervention is too high, it will cause redundant braking capacity, tire locking, and endanger driving safety.

[0004] CN102029986A wheeled chassis brake control method, system and crane with the control system can coordinate and control the service brake device and the auxiliary brake device, and the auxiliary brake device can automatically participate in the service brake operation and share part of the braking force. The existing technical problems are:

[0005] (1) The auxiliary brake output torque is determined only according to the pedal travel, which cannot accurately match the braking requirements of the actual vehicle under different working conditions (such as road driving, heavy-load transfer, etc.);

[0006] (2) The gearbox retarding braking torque and eddy current retarding braking torque of different gears are set in advance by the program, that is, the auxiliary brake output torque is controlled by a general program, which cannot accurately compensate the torque according to the actual road conditions and the actual vehicle status. If the braking torque used for compensation is too small, it will not reduce the burden of the service brake system, and if it is too large, it will cause redundant braking capacity;

[0007] (3) If a circuit of the service brake system fails, the auxiliary braking torque is output according to the change in pedal travel, which cannot compensate for the braking capacity of the service brake system to a greater extent, which may endanger safety during emergency braking;

[0008] (4) If the brake lining is worn, the auxiliary braking torque is output according to the change in pedal travel, which cannot compensate for the braking capacity of the service brake system to a greater extent, which may endanger safety during emergency braking;

[0009] (5) For vehicles equipped with an anti-lock braking system (ABS), when it is determined that the wheels are locked, all auxiliary braking fails (it may be that the gear setting is unreasonable, and only part of the auxiliary braking needs to be withdrawn). The control accuracy is poor and the auxiliary braking effect cannot be maximized. Summary of the invention

[0010] Purpose of the invention: The first purpose of the present invention is to provide a braking compensation control method that executes different braking compensation strategies according to different working conditions; the second purpose of the present invention is to provide a braking compensation control system; the third purpose of the present invention is to provide a crane with the braking compensation control system.

[0011] Technical solution: A braking compensation control method of the present invention formulates different first braking compensation strategies according to the vehicle's factory tire configuration and different axle load conditions. The first braking compensation strategy performs auxiliary braking gear selection according to the pedal stroke; the corresponding first braking compensation strategy is matched according to the collected vehicle axle load condition, and the auxiliary braking of the corresponding gear is selected according to the collected brake pedal stroke signal.

[0012] Furthermore, the same vehicle model can be equipped with a variety of tire models. For different tire models, corresponding brake compensation strategies are formulated and matched according to the same method.

[0013] Furthermore, it is determined whether the actual system air pressure value reaches the theoretical system air pressure value under the same pedal stroke. If not, auxiliary braking and upshifting are performed until the actual system air pressure value reaches the theoretical system air pressure value; similar operations are performed for other pedal strokes.

[0014] Furthermore, according to the number of disconnected ports of each brake caliper wear detection port detected under the same pedal stroke, the auxiliary brake output of the corresponding gear is controlled. The more ports are disconnected, the higher the gear. Similar operations are performed for other pedal strokes.

[0015] Optionally, a braking compensation control method of the present invention is applied to a vehicle equipped with ABS. A second braking compensation strategy is formulated based on the pedal stroke and deceleration. The greater the pedal stroke, the greater the deceleration. The deceleration is calculated based on the collected wheel speed signal to determine whether the deceleration reaches the deceleration corresponding to the collected brake pedal stroke signal. If not, the first gear auxiliary braking is turned on, the wheel speed signal is collected again, the deceleration is calculated, and it is determined whether the deceleration meets the standard. If it still does not meet the standard, the second gear auxiliary braking is turned on, and so on, until the deceleration meets the standard. Similar operations are performed for other pedal strokes.

[0016] Furthermore, the road adhesion coefficient ψ=(F+F i ) / (G g), where F is the braking force generated by the service brake system, F i is the braking force generated by auxiliary brakes in different gears, i represents the gear number; G is the weight of the vehicle, and g is the acceleration due to gravity;

[0017] Determine whether the deceleration reaches the deceleration corresponding to the pedal stroke. If not, turn on the first gear auxiliary brake. At the same time, determine whether the wheel is locked under the pedal stroke based on the collected brake pedal stroke signal. If not, record the auxiliary brake gear at this time; then make a deceleration judgment. If not, turn on the second gear auxiliary brake, and so on, until the wheel locks, and record the maximum road adhesion coefficient; determine the previous gear before the wheel locks as the highest gear under the pedal stroke; by continuously correcting the road adhesion coefficient, match the braking compensation strategy when the vehicle is driving on different roads.

[0018] Furthermore, if the ABS fails, the above-mentioned braking compensation control method is executed.

[0019] Optionally, a braking compensation control method of the present invention is applied to a vehicle equipped with EBS to execute the above-mentioned braking compensation control method; if within a certain pedal stroke, the corresponding deceleration cannot be achieved after turning on the highest-level auxiliary braking, the EBS intervenes to increase the output braking torque for compensation while keeping the electronically controlled brake pedal stroke unchanged; similar operations are performed for other pedal strokes.

[0020] Furthermore, if the EBS fails, the above-mentioned braking compensation control method is executed.

[0021] A braking compensation control system of the present invention includes a service braking system and an auxiliary braking system, and further includes:

[0022] Information collection system, which obtains brake pedal travel signal and vehicle axle load status;

[0023] The controller matches the first brake compensation strategy according to the vehicle axle load state, and controls the auxiliary braking of the corresponding gear according to the brake pedal travel signal.

[0024] Furthermore, the information collection system also obtains the actual air pressure value of the system in real time; the controller also determines whether the actual air pressure value of the system reaches the theoretical air pressure value of the system under the same pedal stroke. If not, auxiliary braking and upshifting are performed until the actual air pressure value of the system reaches the theoretical air pressure value of the system; similar operations are performed for other pedal strokes.

[0025] Furthermore, the air pressure value collection point is set to be the air outlet of the foot brake valve or the brake air chamber interface on the axle.

[0026] Furthermore, the information collection system also obtains the on and off status of each brake caliper wear detection port in real time; the controller also controls the output of the auxiliary brake of the corresponding gear according to the number of disconnected ports of each brake caliper wear detection port under the same pedal stroke. The more ports are disconnected, the higher the gear; similar operations are performed for other pedal strokes.

[0027] Furthermore, when the brake caliper wear detection port is disconnected, the controller also outputs a signal to light up the brake wear detection light to remind the driver to stop the car and check.

[0028] Furthermore, the auxiliary braking system is equipped with a transmission retarder brake, an eddy current retarder and an engine braking device; when a certain auxiliary braking device fails or reaches a preset safety value, the controller also controls to increase the output gear of other auxiliary braking devices; when a certain auxiliary braking device fails or reaches a preset safety value, the controller also sends an alarm signal and lights up the alarm light, prompting the driver to implement active braking in time.

[0029] Optionally, a braking compensation control system of the present invention includes a service braking system and an auxiliary braking system, and further includes:

[0030] Information collection system, real-time acquisition of wheel speed signals and brake pedal travel signals;

[0031] ABS controller, used to convert real-time wheel speed signals into deceleration;

[0032] The controller determines whether the deceleration reaches the deceleration corresponding to the collected brake pedal travel signal. If not, a signal is sent to turn on the first gear auxiliary brake, and then the deceleration is determined. If it is still not reached, a signal is sent to turn on the second gear auxiliary brake, and so on, until the deceleration reaches the standard; similar operations are performed for other pedal travels.

[0033] Furthermore, the information collection system also obtains the road adhesion coefficient, road adhesion coefficient ψ=(F+F i ) / (G g), where F is the braking force generated by the service brake system, F i is the braking force generated by auxiliary brakes in different gears, i represents the gear number; G is the weight of the vehicle, and g is the acceleration due to gravity;

[0034] The controller also determines whether the deceleration reaches the deceleration corresponding to the pedal stroke. If not, a signal is sent to turn on the first gear auxiliary brake. At the same time, it determines whether the wheel is locked under the pedal stroke based on the collected brake pedal stroke signal. If not, the auxiliary brake gear at this time is recorded; the deceleration is judged again. If not, a signal is sent to turn on the second gear auxiliary brake, and so on, until the wheel is locked, and the maximum road adhesion coefficient is recorded; the gear before the wheel is locked is determined as the highest gear under the pedal stroke; by continuously correcting the road adhesion coefficient, the braking compensation strategy is matched when the vehicle is driving on different roads.

[0035] Furthermore, the auxiliary braking system is equipped with a transmission retarder brake, an eddy current retarder and an engine braking device; if within a certain pedal stroke, the theoretical deceleration cannot be achieved after turning on the highest-level auxiliary braking, the controller controls the continuous output of all auxiliary braking; when a certain auxiliary braking device fails or reaches a preset safety value, the controller also controls the increase of the output gear of other auxiliary braking devices; when a certain auxiliary braking device fails or reaches a preset safety value, the controller also sends an alarm signal and lights up the alarm light, prompting the driver to implement active braking in time.

[0036] Furthermore, if the ABS fails, the controller turns on the ABS fault light according to the acquired ABS fault signal.

[0037] Optionally, a braking compensation control system of the present invention includes a service braking system and an auxiliary braking system, and further includes:

[0038] Information collection system, real-time acquisition of wheel speed signals and brake pedal travel signals;

[0039] The EBS controller converts the real-time wheel speed signal into deceleration;

[0040] The controller determines whether the deceleration reaches the deceleration corresponding to the collected brake pedal stroke signal. If not, a signal is sent to turn on the first gear auxiliary brake, and then the deceleration is determined. If it is still not reached, a signal is sent to turn on the second gear auxiliary brake, and so on, until the deceleration reaches the standard; similar operations are performed for other pedal strokes;

[0041] When the corresponding deceleration cannot be achieved after turning on the highest level auxiliary braking, the EBS controller also outputs a signal to increase the output braking torque of the electronically controlled brake pedal to compensate while maintaining the stroke unchanged.

[0042] Furthermore, if the EBS fails, the controller also lights up the EBS fault light according to the acquired EBS fault signal.

[0043] A crane of the present invention comprises the above-mentioned braking compensation control system.

[0044] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0045] The present invention can better coordinate and control the braking capacity of the service brake system and the auxiliary brake system, calibrate according to the different axle load states and tire sizes of the actual vehicle, and formulate a brake compensation strategy. When the service brake system is intact, the brake circuit fails, the brake is worn, and the auxiliary brake capacity is insufficient, a brake compensation strategy is given respectively, which can not only reduce the burden of the service brake system and maintain the stability of the vehicle's braking capacity, but also greatly improve the safety of the vehicle's braking when the service brake system fails. Specifically:

[0046] When the service brake system is in good condition, the auxiliary brakes of different gears are controlled and output for torque compensation according to different brake pedal travel signals to reduce the burden on the service brake device; when the service brake system circuit fails or the brake lining is worn, the auxiliary brake gear is automatically increased to increase the output braking torque according to the severity of the circuit failure and brake wear, thereby compensating for the braking capacity of the whole vehicle and improving the safety and economy of the vehicle's braking.

[0047] For vehicles equipped with anti-lock braking systems, deceleration is introduced as a braking system performance indicator to optimize the compensation strategy and more accurately control the auxiliary braking gear for intervention compensation.

[0048] For vehicles equipped with EBS, the service braking capacity is compensated by adjusting the braking torque output ratio under the same pedal stroke when the auxiliary braking capacity is insufficient or the auxiliary braking device fails. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a structural schematic diagram of a brake compensation control system for a four-axle crane in an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The present invention will be further described below in conjunction with the accompanying drawings.

[0051] The technical solution of the present invention is described by taking a four-bridge crane as an example. Figure 1The figure shows the structure diagram of the brake compensation control system of a four-axle crane. The brake compensation control system includes a service brake system, an auxiliary brake system, a signal acquisition system, a storage system, a control system, etc., wherein the service brake system provides the vehicle with a driving braking torque; the auxiliary brake system generally includes engine exhaust brake, engine retarding brake, gearbox retarding brake and eddy current retarding brake, etc., which provide auxiliary braking torque for the vehicle; the signal acquisition system is a broad concept, including several related parameter components or elements, such as a collection device for obtaining the vehicle axle load state, a collection device for obtaining the air pressure of the brake system, a collection device for obtaining the brake pedal stroke and the accelerator pedal stroke, and a collection device for obtaining the vehicle wheel speed; the storage system stores the established parameters of the vehicle itself, including the tire radius, the braking force of each axle, and the axle load under different driving conditions; the control system includes a controller for calculating and processing various signals, such as an engine brake device controller, a gearbox retarding device controller, an ABS controller, an EBS controller, etc.

[0052] The following introduces the brake compensation control method in combination with the brake compensation control system.

[0053] Example 1

[0054] 1) The implementation process of the brake compensation system when the service brake system is intact.

[0055] When the service brake system is in good condition, it is calibrated according to the different axle load states and tire sizes of the actual vehicle, and the brake compensation strategy for the vehicle in different states is formulated: for a vehicle with a certain driving state, the service brake torque output by different pedal strokes is also determined accordingly, so the auxiliary brakes of different gears can be controlled to output torque compensation according to different brake pedal stroke signals to reduce the burden on the service brake device. Specifically:

[0056] Before the vehicle leaves the factory, the tire configuration has been determined, so it is calibrated according to the commonly used axle load state formulated in the vehicle overall plan. For example, in the highway driving state, the axle load is less than 12 tons, and the brake compensation strategy 1 can be formulated: when the pedal stroke is 5%L≤i<25%L (L is the total pedal stroke), it is equivalent to the auxiliary brake enabling and selecting the auxiliary brake of the first gear at the same time; when the pedal stroke is 25%L≤i<50%L, it is equivalent to the auxiliary brake enabling and selecting the auxiliary brake of the second gear at the same time; when the pedal stroke is 50%L≤i<75%L, it is equivalent to the auxiliary brake enabling and selecting the auxiliary brake of the third gear at the same time; when the pedal stroke is 75%L≤i<100%L, it is equivalent to the auxiliary brake enabling and selecting the auxiliary brake of the fourth gear at the same time.

[0057] For example, when the vehicle is in a heavy-load driving state (there may be multiple heavy-load driving states), the axle load is 12 to 18 tons, and a second braking compensation strategy may be formulated: when the pedal stroke is 5% L≤i<25% L, it is equivalent to enabling the auxiliary braking and selecting the auxiliary braking of the second gear at the same time; when the pedal stroke is 25% L≤i<50% L, it is equivalent to enabling the auxiliary braking and selecting the auxiliary braking of the third gear at the same time; when the pedal stroke is 50% L≤i<100% L, it is equivalent to enabling the auxiliary braking and selecting the auxiliary braking of the fourth gear at the same time.

[0058] Similarly, different braking compensation strategies can be formulated according to the same method for other axle load conditions and tire configurations (the same vehicle model can be equipped with multiple tire models), which will not be elaborated here.

[0059] During normal driving, when the driver steps on the driving brake pedal, the controller automatically selects the brake compensation strategy based on the actual axle load status of the vehicle collected by the information acquisition system, and at the same time collects the brake pedal travel signal actually stepped on by the driver, and controls the output of the auxiliary brake of the corresponding gear.

[0060] 2) The implementation process of the brake compensation system when the service brake system fails.

[0061] When a fault occurs in the service brake system, it generally manifests as circuit failure and brake wear. Since the probability of circuit failure and brake wear occurring at the same time is small, only the solution to the single fault of circuit failure or brake wear is analyzed.

[0062] 2.1) When the service brake system circuit fails:

[0063] As mentioned above, for a vehicle with a certain driving state, the braking torque that can be output by its service brake system is determined, and the service braking torque that should be output for different pedal strokes is also determined accordingly. The braking torque that can be output and the system air pressure that can be achieved have a corresponding relationship. Assuming that the vehicle's service braking torque is M, and the system air pressure value at this time is C, then the two satisfy M=f(C). Then when the pedal stroke is 5%L≤i<25%L, 25%L≤i<50%L, 50%L≤i<75%L and 75%L≤i<100%L, the service braking torque that should be output in theory is M1, M2, M3 and M4 respectively, and the corresponding air pressure values ​​that can be achieved are C1, C2, C3 and C4 respectively.

[0064] When the vehicle applies service brakes during driving, the braking torque actually output by each pedal stroke is set as M 11 、M 22 、M 33 and M 44 , then the actual pressure values ​​that the corresponding system can reach are C 11 , C 22 , C 33 and C44 , theoretically, the relationship C should be satisfied ii =C i (i=1,2,3,4).

[0065] When the service brake system fails, the system air pressure will decrease, and within the same pedal stroke, there will be C ii <C i (i=1,2,3,4), the output braking torque will also be reduced. Therefore, the output gear of the auxiliary braking system can be controlled by judging whether the actual system air pressure value reaches the theoretical system air pressure value. Specifically:

[0066] Under the condition of 12t axle load, during normal vehicle driving, the controller obtains the actual air pressure value C of the system in real time. ii When the driver steps on the brake pedal 5%L≤i<25%L, the controller obtains the brake pedal travel and controls the opening of the first gear auxiliary brake. The controller determines whether there is C 11 <C1, if it is satisfied, a signal is sent to the auxiliary brake system to output the second gear auxiliary brake; the controller determines again whether there is C 11 <C1, if it is satisfied, a signal is sent to the auxiliary brake system to output the third gear auxiliary brake; and so on, until the actual air pressure value reaches the theoretical air pressure value. The control methods under other pedal travels are similar to this and will not be repeated.

[0067] It should be noted that the setting point of the theoretical air pressure value and the collection point of the actual air pressure value are not fixed, and there are multiple options. For example, the outlet of the foot brake valve can be selected as the air pressure value collection point. The components of this solution are arranged more concentratedly, the cost is lower, but the control accuracy is poor; for another example, the brake air chamber interface on the axle can be selected as the air pressure value collection point. The components of this solution are arranged more dispersedly, the control accuracy is higher, but it will cost more. It should be noted that this example uses the outlet of the foot brake valve as the air pressure value collection point, which is only one of the specific cases. As long as the basic concept of this solution is applied, it is within the scope of protection requested by this application.

[0068] 2.2) When the brakes are worn:

[0069] For chassis using disc brakes, a brake wear detection line is generally configured in the brake caliper. The wear detection line in the brake caliper of each axle is connected to the controller using a port. When braking is applied, if the brake lining is severely worn, the detection line in the caliper will be worn off. The controller also analyzes and calculates the severity of brake wear (single caliper wear or multiple caliper wear) according to the on-off status of different ports to control the output of auxiliary braking torque for different gears. At the same time, the output signal will light up the brake wear detection light to remind the driver to stop and check.

[0070] The braking force applied by the brake on the wheel is determined by the structure of the brake itself and the brake air chamber configured on the brake disc. For multi-axle vehicles, the braking torque of different axle configurations will be different. For example, a four-axle crane has double-caliper discs for the first and second axles, each with four brake calipers applying braking force, and a driving braking torque of 100,000 N·m for each axle. The third and fourth axles have single-caliper discs, each with two brake calipers applying braking force, and a driving braking torque of 50,000 N·m for each axle. The total driving braking torque of the vehicle is 300,000 N·m. If one or more brake linings are severely worn, the magnitude of the lost braking torque can be calculated by obtaining the on-off status of each wear detection port.

[0071] During normal driving, the controller can detect the status of each brake wear detection port in real time. If a brake lining is seriously worn, when the driver steps on the driving brake pedal, the controller controls the start of auxiliary brakes in different gears according to the number of wear detection ports disconnected. For example, in the state of axle load of 12t, when there is no brake wear, the pedal stroke is 5%L≤i<25%L, and the first gear auxiliary brake is started. If one of the brake linings is worn, the controller obtains that one wear detection port is disconnected, and then sends a signal to control the auxiliary brake to automatically rise to the second gear; if two of the brake linings are worn, the controller obtains that two wear detection ports are disconnected, and then sends a signal to control the auxiliary brake to automatically rise to the third gear; if more than three of the brake linings are worn, the controller obtains that more than three wear detection ports are disconnected, and then sends a signal to control the auxiliary brake to automatically rise to the fourth gear, and all auxiliary brakes are started. For pedal strokes in other states, the brake compensation strategy is also specified in this way.

[0072] It should be noted that the 5%L≤i<25%L, 25%L≤i<50%L, 50%L≤i<75%L and 75%L≤i<100%L brake pedal strokes divided in the present invention are only a specific case of this example. In fact, different vehicle models and foot brake valve characteristics can have different gear divisions. As long as the basic concept of this scheme is applied, it is within the scope of protection requested by this application. The first, second, third and fourth gear auxiliary brakes mentioned in the present invention correspond to the first, second, third and fourth gears of the gearbox brake device and the first, second, third and fourth gears of the eddy current brake device, respectively. It should be understood that the above-mentioned gear division is only a specific case of this example. In fact, according to different vehicle models and different gearbox brake and eddy current brake configurations, there can be other different gear divisions (three or five gears, etc.). It is particularly important to explain that the auxiliary braking configuration of the best solution in this example includes a gearbox braking device, an eddy current braking device and an engine braking device. Several auxiliary braking configurations can be selected according to different loads and operating conditions. As long as the basic concept of this solution is applied, it is within the scope of protection requested in this application.

[0073] Transmission retarding braking: The braking force output by the hydraulic retarder installed on the transmission can help the driver control the vehicle speed and share the pressure of the vehicle's main brake system when going down a long slope, allowing the vehicle to pass through the long downhill section stably and safely, thereby improving vehicle operating efficiency, reducing brake wear, and extending tire life.

[0074] Eddy current retarder braking: The braking force is output by the eddy current retarder installed between the gearbox and the drive axle, which can bear 50% to 90% of the braking capacity, which can greatly reduce the wear and high temperature of the wheel brakes, ensure that the brakes are in good working condition, and thus alleviate or avoid safety hazards such as vehicle deviation, make the vehicle brake more stable, and effectively reduce the noise during braking.

[0075] Engine braking: After starting, the operation mode of the engine exhaust valve can be changed, so that the engine becomes an air compressor that absorbs power, and then transmits the deceleration force to the drive wheels. Engine braking can be subdivided into exhaust braking, cylinder braking and retarding braking.

[0076] It should be noted that if a certain auxiliary braking device fails or reaches a preset safety value, the output gear of other auxiliary braking devices will be increased. For example, when the oil temperature of the transmission retarder is greater than the preset safety value, the transmission controller outputs a signal to shut down the transmission retarder, and at the same time outputs an alarm signal to the vehicle controller, and the controller outputs a signal to start a higher-level eddy current brake; for example, when the voltage signal of the eddy current retarder is lower than the safety value or the temperature is higher than the safety value, the eddy current brake will be automatically released, and the controller outputs a signal to start a higher-level transmission brake. When an auxiliary braking device fails or reaches a preset safety value, it will send an alarm signal to the vehicle controller to light up the alarm light on the display, prompting the cab to implement active braking in time (such as stepping on the brake pedal deeply or implementing emergency braking, etc.).

[0077] Example 2

[0078] 3) Implementation process of the brake compensation system for vehicles equipped with ABS.

[0079] This example is applicable to vehicles equipped with an anti-lock braking system (hereinafter referred to as ABS).

[0080] For vehicles equipped with ABS, wheel speed signals can be collected through ABS wheel speed sensors installed on the axle wheels or the main reducer. The wheel speed signals can be further converted into fully emitted braking deceleration (hereinafter referred to as "deceleration"). As we all know, deceleration can be used as an indicator to evaluate the performance of the braking system. For vehicles with certain braking system performance requirements, the deceleration that can be achieved with different pedal strokes should be determined. Then, by calibrating the deceleration values ​​that should be achieved with different pedal strokes to formulate a braking compensation strategy to control the output of the auxiliary brake device gear position, the auxiliary brake device capacity can be used more accurately, and the braking safety performance can be further improved.

[0081] When the service brake system is in good condition, the brake compensation strategy can be calibrated according to the pedal travel and deceleration. For example, when the axle load is 12t and the pedal travel is 5%L≤i<25%L, the brake deceleration should be 2m / s. 2 ; When the pedal travel is 25%L≤i<50%L, the braking deceleration should be 3m / s 2 , pedal travel 50%L≤i<75%L, the braking deceleration should be 4m / s 2 ; When the pedal travel i≥75%L, the braking deceleration should be 5m / s 2 .

[0082] During normal vehicle driving, when the driver steps on the brake pedal 5%L≤i<25%L, the ABS controller obtains and calculates the deceleration based on the wheel speed signal and sends the deceleration to the controller, which determines whether the deceleration reaches 2m / s 2 If it is not reached, a signal is sent to the auxiliary brake device to open the first gear auxiliary brake; the wheel speed sensor collects the wheel speed signal again, the ABS controller obtains the wheel speed signal and calculates the deceleration, and sends the deceleration size to the controller, and the controller again determines whether the deceleration reaches 2m / s 2 If it is not reached, a signal is sent to the auxiliary brake device to open the second gear auxiliary brake, and so on. The implementation process corresponding to other pedal strokes is similar to this and will not be repeated.

[0083] For vehicles equipped with ABS, when the service brake circuit fails or the brake lining is severely worn, there is no need to formulate a brake compensation strategy based on the actual output air pressure value and brake wear detection. Auxiliary brake compensation can be directly used with deceleration as the reference standard.

[0084] It should be noted that when executing the brake compensation strategy, if the theoretical deceleration cannot be achieved after the fourth gear auxiliary brake is turned on within a certain pedal stroke, all auxiliary brakes will continue to be output. If a certain auxiliary brake device fails or reaches a preset safety value, the output gear of other auxiliary brake devices will be increased. For example, when the oil temperature of the transmission retarder is greater than the preset safety value, the transmission controller outputs a signal to shut down the transmission retarder, and at the same time outputs an alarm signal to the vehicle controller, and the controller outputs a signal to turn on the eddy current brake of a higher gear; for example, when the voltage signal of the eddy current retarder is lower than the safety value or the temperature is higher than the safety value, the eddy current brake will be automatically released, and the controller outputs a signal to turn on the transmission brake of a higher gear. When the auxiliary brake device fails or reaches the preset safety value, it will send an alarm signal to the vehicle controller to light up the alarm light on the display, prompting the cab to implement active braking in time (such as stepping on the foot brake pedal deeply or implementing emergency braking, etc.).

[0085] Furthermore, the braking compensation strategy can be matched to the vehicle when driving on different roads by continuously correcting the road adhesion coefficient. It is easy to know that the road adhesion coefficient can be calculated based on the braking force generated by the vehicle and the weight of the vehicle. Assume that the braking force generated by the service brake system is F, and the braking force generated by the auxiliary brakes in different gears is F i (i=1,2,3,4), the vehicle weight is G, and the utilization rate of the adhesion coefficient is ψ, then there exists ψ=(F+F i ) / (G·g). It can be seen that under the premise that the wheels are not locked, when the braking force is maximized, the maximum road adhesion coefficient can be obtained. Since the driving braking force configured by the vehicle when it leaves the factory has been determined, the road adhesion coefficient can be continuously corrected through the self-learning ability of ABS during vehicle calibration to reach the maximum value, thereby determining the size of the auxiliary braking force controlled output. Specifically:

[0086] During normal vehicle driving, when the driver steps on the brake pedal 5%L≤i<25%L, the ABS controller obtains and calculates the deceleration based on the wheel speed signal and sends the deceleration to the controller, which determines whether the deceleration reaches 2m / s 2 If it is not reached, a signal is sent to the auxiliary brake device to open the first gear of auxiliary brake; at the same time, the ABS controller obtains the brake pedal travel and determines whether the wheel is locked under this travel. If not, the auxiliary brake gear position is recorded at this time; the ABS controller obtains and determines again whether the deceleration reaches 2m / s 2, if not, a signal is sent to the auxiliary brake device to turn on the second gear auxiliary brake; at the same time, the ABS controller obtains the brake pedal travel and determines whether the wheel is locked under this travel. If the wheel is locked, it means that the adhesion coefficient utilization has reached the maximum, and the ABS will record the highest road adhesion coefficient; then when the brake pedal travel is 5%L≤i<25%L, the system controller will consider that the first gear auxiliary brake is turned on at the highest; according to ψ=(F+F i ) / (G·g), the system can self-learn the highest gear that can open auxiliary braking within other pedal travel. According to this control method, the vehicle will be greatly reduced from braking and locking, and the braking safety will be improved.

[0087] In particular, if the ABS fails, the controller obtains an ABS fault signal, turns on the ABS fault light, and automatically selects the brake compensation strategy described in sequence number 1) and sequence number 2) for execution.

[0088] Example 3

[0089] 4) Implementation process of brake compensation system for vehicles equipped with ABS

[0090] This example is applicable to vehicles equipped with an electronically controlled braking system (hereinafter referred to as EBS), and the anti-lock braking function is integrated into the EBS.

[0091] For vehicles equipped with an electronically controlled braking system, the electronically controlled brake pedal ratio can be adjusted to compensate for the vehicle's braking capacity when a fault occurs in the service brake circuit, the brake lining is severely worn, or the auxiliary braking capacity is insufficient.

[0092] When the service brake system is in good condition, the brake compensation system automatically controls the output auxiliary brake gear for torque compensation according to the deceleration.

[0093] When the travel brake circuit fails or brake wear occurs, in addition to starting the auxiliary brake for torque compensation, EBS can also be used to increase the driving braking torque. As mentioned above, for the vehicle determined by the plan, the braking force that each axle can provide and the braking force that each auxiliary braking device can provide are determined. In the pneumatic brake system, the braking torque output for different strokes of the brake pedal is also determined. However, for vehicles using EBS, the output braking torque corresponding to different strokes of the electronically controlled brake pedal can be adjusted through the EBS controller. Therefore, the EBS controller can output a signal to increase the output braking torque for compensation while keeping the stroke of the electronically controlled brake pedal unchanged. Specifically:

[0094] For a four-axle crane, the total driving braking torque is 300,000 N·m. When the axle load is 12t and the pedal stroke is 5%L≤i<25%L, the braking torque to be output is 20% of the total braking torque, that is, 60,000 N·m. When the ideal braking performance cannot be achieved after the auxiliary braking device is fully involved, the EBS can control the pedal stroke to remain unchanged and increase the output braking torque to 30% of the total braking torque, that is, 90,000 N·m. When the pedal stroke is 25%L≤i<50%L, the braking torque to be output is 40% of the total braking torque, that is, 120,000 N·m. When the ideal braking performance cannot be achieved after the auxiliary braking device is fully involved, the EBS can control the pedal stroke to remain unchanged and increase the output braking torque to 50% of the total braking torque, that is, 150,000 N·m. The compensation situations under other pedal strokes are similar and will not be repeated.

[0095] It should be noted that the percentage of braking torque corresponding to the brake pedal stroke mentioned in the present invention is only a specific case of this embodiment. In fact, according to the braking force distribution of different vehicle models, the pedal stroke can be divided into other gears, and different pedal strokes and output braking torques can also have different corresponding relationships. As long as the basic concept of this solution is applied, it is within the scope of protection requested in this application.

[0096] For vehicles equipped with EBS, when the driving circuit fails or brake wear occurs, the compensation system is implemented as follows: if the axle load is 12t and the pedal travel is 25%L≤i<50%L, the braking deceleration to be achieved is 3m / s 2 ; The EBS controller obtains and calculates the deceleration based on the wheel speed signal and sends the deceleration to the controller; The controller compares whether the deceleration reaches 3m / s 2 If it is not reached, a signal is sent to the auxiliary brake device to start the first gear auxiliary brake acquisition; after cyclic collection, calculation and judgment, if the deceleration still cannot reach 3m / s after all the auxiliary brakes are turned on 2 At this time, EBS intervenes and adjusts, increasing the output braking torque to 30% of the total braking torque, that is, 90000N·m. The implementation ideas of the brake compensation system under other pedal travels are similar and will not be repeated here.

[0097] Vehicles equipped with EBS can not only compensate for torque when the service brake circuit fails or brake wear occurs, but also compensate when part or all of the auxiliary brake device fails to function normally. It is easy to know that in the auxiliary brake device, when the oil temperature of the transmission retarder brake is greater than the preset safety value, the control signal to the transmission retarder will be shut down, and an alarm signal will be output at the same time; the eddy current retarder will automatically release the eddy current brake and issue an alarm signal when the voltage signal is lower than the safety value or the temperature is higher than the safety value; the engine brake device itself can provide a small braking torque. Therefore, when the torque provided by the auxiliary brake is insufficient, increasing the output braking torque through EBS adjustment will greatly improve braking safety.

[0098] In particular, if the EBS fails, the controller obtains an EBS fault signal, turns on the EBS fault light, and automatically selects the brake compensation strategy described in sequence number 1) and sequence number 2) for execution.

[0099] Example 4

[0100] A crane comprises the aforementioned braking compensation control system.

Claims

1. A braking compensation control method, characterized in that: Different first brake compensation strategies are formulated according to the vehicle's factory tire configuration and different axle load conditions. The first brake compensation strategy performs auxiliary braking gear selection according to the pedal stroke; the corresponding first brake compensation strategy is matched according to the collected vehicle axle load status, and the auxiliary braking of the corresponding gear is selected according to the collected brake pedal travel signal.

2. The brake compensation control method according to claim 1, characterized in that: The same vehicle model can be equipped with a variety of tire models. For different tire models, corresponding brake compensation strategies are formulated and matched according to the same method.

3. The braking compensation control method according to claim 1, characterized in that: Determine whether the actual air pressure value of the system reaches the theoretical air pressure value of the system under the same pedal stroke. If not, perform auxiliary braking to shift up until the actual air pressure value of the system reaches the theoretical air pressure value of the system. The other pedal strokes proceed similarly.

4. The brake compensation control method according to claim 1, characterized in that: According to the number of disconnected ports of each brake caliper wear detection port detected under the same pedal stroke, the auxiliary brake of the corresponding gear is controlled to output. The more the number of disconnected ports is, the higher the gear is. The other pedal strokes proceed similarly.

5. A braking compensation control method, applied to a vehicle equipped with ABS, characterized in that: According to the pedal travel and deceleration, a second brake compensation strategy is formulated. The greater the pedal travel, the greater the deceleration. The deceleration is calculated according to the collected wheel speed signal to determine whether the deceleration reaches the deceleration corresponding to the collected brake pedal travel signal. If not, the first gear auxiliary brake is turned on, the wheel speed signal is collected again, the deceleration is calculated, and it is determined whether the deceleration reaches the standard. If it still does not reach the standard, the second gear auxiliary brake is turned on, and so on, until the deceleration reaches the standard. The other pedal strokes proceed similarly.

6. The braking compensation control method according to claim 5, characterized in that: Road adhesion coefficient ψ=(F+F i ) / (G g), where F is the braking force generated by the service brake system, F i is the braking force generated by auxiliary brakes in different gears, i represents the gear number; G is the weight of the vehicle, and g is the acceleration due to gravity; Determine whether the deceleration reaches the deceleration corresponding to the pedal stroke. If not, turn on the first gear auxiliary brake. At the same time, determine whether the wheel is locked under the pedal stroke based on the collected brake pedal stroke signal. If not, record the auxiliary brake gear at this time; then make a deceleration judgment. If not, turn on the second gear auxiliary brake, and so on, until the wheel locks, and record the maximum road adhesion coefficient; determine the previous gear before the wheel locks as the highest gear under the pedal stroke; by continuously correcting the road adhesion coefficient, match the braking compensation strategy when the vehicle is driving on different roads.

7. The braking compensation control method according to claim 5 or 6, characterized in that: If the ABS fails, the braking compensation control method according to any one of claims 1 to 4 is executed.

8. A braking compensation control method, applied to a vehicle equipped with an EBS, characterized in that: Execute the brake compensation control method described in claim 5 or 6; if within a certain pedal stroke, the corresponding deceleration cannot be achieved after turning on the highest-level auxiliary brake, the EBS intervenes to increase the output braking torque for compensation while keeping the electronic control brake pedal stroke unchanged; similar operations are performed for other pedal strokes.

9. The brake compensation control method according to claim 8, characterized in that: If the EBS fails, the braking compensation control method according to any one of claims 1 to 4 is executed.

10. A brake compensation control system, comprising a service brake system and an auxiliary brake system, characterized in that: Also includes: Information collection system, which obtains brake pedal travel signal and vehicle axle load status; The controller matches the first brake compensation strategy according to the vehicle axle load state, and controls the auxiliary braking of the corresponding gear according to the brake pedal travel signal.

11. The brake compensation control system according to claim 10, characterized in that: The information collection system also obtains the actual air pressure value of the system in real time; the controller also determines whether the actual air pressure value of the system reaches the theoretical air pressure value of the system under the same pedal stroke. If not, auxiliary braking and upshifting are performed until the actual air pressure value of the system reaches the theoretical air pressure value of the system; The other pedal strokes proceed similarly.

12. The brake compensation control system according to claim 11, characterized in that: The air pressure value collection point is set to the air outlet of the foot brake valve or the brake air chamber interface on the axle.

13. The brake compensation control system according to claim 10, characterized in that: The information collection system also obtains the on / off status of each brake caliper wear detection port in real time; the controller also controls the output of the auxiliary brake of the corresponding gear according to the number of disconnected ports of each brake caliper wear detection port under the same pedal stroke. The more ports are disconnected, the higher the gear. The other pedal strokes proceed similarly.

14. The brake compensation control system according to claim 13, characterized in that: When the brake caliper wear detection port is disconnected, the controller also outputs a signal to light up the brake wear detection light to remind the driver to stop and check.

15. The brake compensation control system according to any one of claims 10 to 14, characterized in that: The auxiliary braking system is equipped with a transmission retarder brake, an eddy current retarder and an engine braking device; when a certain auxiliary braking device fails or reaches a preset safety value, the controller also controls to increase the output gear of other auxiliary braking devices; when a certain auxiliary braking device fails or reaches a preset safety value, the controller also sends an alarm signal and lights up the alarm light to prompt the driver to implement active braking in time.

16. A brake compensation control system, comprising a service brake system and an auxiliary brake system, characterized in that: Also includes: Information collection system, real-time acquisition of wheel speed signals and brake pedal travel signals; ABS controller, used to convert real-time wheel speed signals into deceleration; The controller determines whether the deceleration reaches the deceleration corresponding to the collected brake pedal travel signal. If not, a signal is sent to turn on the first gear auxiliary brake, and then the deceleration is determined. If it is still not reached, a signal is sent to turn on the second gear auxiliary brake, and so on, until the deceleration reaches the standard; similar operations are performed for other pedal travels.

17. The brake compensation control system according to claim 16, characterized in that: The information collection system also obtains the road adhesion coefficient, which is ψ = (F + F i ) / (G g), where F is the braking force generated by the service brake system, F i is the braking force generated by auxiliary brakes in different gears, i represents the gear number; G is the weight of the vehicle, and g is the acceleration due to gravity; The controller also determines whether the deceleration reaches the deceleration corresponding to the pedal stroke. If not, a signal is sent to turn on the first gear auxiliary brake. At the same time, it determines whether the wheel is locked under the pedal stroke based on the collected brake pedal stroke signal. If not, the auxiliary brake gear at this time is recorded; the deceleration is judged again. If not, a signal is sent to turn on the second gear auxiliary brake, and so on, until the wheel is locked, and the maximum road adhesion coefficient is recorded; the gear before the wheel is locked is determined as the highest gear under the pedal stroke; by continuously correcting the road adhesion coefficient, the braking compensation strategy is matched when the vehicle is driving on different roads.

18. The brake compensation control system according to claim 16, characterized in that: The auxiliary braking system is equipped with a transmission retarder brake, an eddy current retarder and an engine braking device; if within a certain pedal stroke, the theoretical deceleration cannot be achieved after turning on the highest-level auxiliary braking, the controller controls the continuous output of all auxiliary braking; when a certain auxiliary braking device fails or reaches a preset safety value, the controller also controls to increase the output gear of other auxiliary braking devices; when a certain auxiliary braking device fails or reaches a preset safety value, the controller also sends an alarm signal and lights up the alarm light, prompting the driver to implement active braking in time.

19. The brake compensation control system according to claim 16, characterized in that: If the ABS fails, the controller will light up the ABS fault light based on the ABS fault signal obtained.

20. A brake compensation control system, comprising a service brake system and an auxiliary brake system, characterized in that: Also includes: Information collection system, real-time acquisition of wheel speed signals and brake pedal travel signals; The EBS controller converts the real-time wheel speed signal into deceleration; The controller determines whether the deceleration reaches the deceleration corresponding to the collected brake pedal stroke signal. If not, a signal is sent to turn on the first gear auxiliary brake, and then the deceleration is determined. If it is still not reached, a signal is sent to turn on the second gear auxiliary brake, and so on, until the deceleration reaches the standard; similar operations are performed for other pedal strokes; When the corresponding deceleration cannot be achieved after turning on the highest level auxiliary braking, the EBS controller also outputs a signal to increase the output braking torque of the electronically controlled brake pedal to compensate while maintaining the stroke unchanged.

21. The brake compensation control system according to claim 20, characterized in that: If the EBS fails, the controller will also light up the EBS fault light based on the EBS fault signal obtained.

22. A crane, characterized in that: The invention comprises the braking compensation control system according to any one of claims 10 to 21.

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