Braking method and braking system of commercial vehicle and commercial vehicle

Abstract

The invention provides a braking method and system of a commercial vehicle and the commercial vehicle. The braking method comprises the steps that under the condition that a working mode is a braking mode, the total braking force demand value of the vehicle and the maximum auxiliary braking force value capable of being provided by an auxiliary braking system are calculated according to the current operation working condition of the vehicle; when the total demand value of the braking force is not larger than the maximum auxiliary braking force value, the auxiliary braking system is controlled to conduct braking according to the total demand value of the braking force; and when the total demand value of the braking force is larger than the maximum auxiliary braking force value, the auxiliary braking system is controlled to conduct braking according to the maximum auxiliary braking force value, and a main braking system is controlled to conduct braking according to the difference value between the total demand value of the braking force and the maximum auxiliary braking force value. According to the braking method of the commercial vehicle, the braking effect of the auxiliary braking system can be exerted to the maximum extent so that braking energy can be recycled, and the energy recycling performance of the vehicle can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle braking, and in particular to a braking method for a commercial vehicle. In addition, the present invention also relates to a braking system and a commercial vehicle. Background Art

[0002] In the prior art, commercial vehicles have high performance requirements for the braking system. For example, heavy commercial vehicles require a large total braking force under braking or deceleration conditions due to their large weight and high running speed. If traditional air brakes are used for braking, there will be two disadvantages: first, frequent operation will increase the temperature of friction parts such as brake pads and affect the stability and service life of the braking system; second, the kinetic energy loss caused by braking will affect the driving economy of the vehicle. Summary of the invention

[0003] In view of this, the present invention aims to provide a braking method for a commercial vehicle to improve the braking effect of the vehicle.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0005] A braking method for a commercial vehicle, comprising:

[0006] When the working mode is the braking mode, the total braking force requirement of the vehicle and the maximum auxiliary braking force value that the auxiliary braking system can provide are calculated according to the current operating conditions of the vehicle;

[0007] When the total braking force requirement value is not greater than the maximum auxiliary braking force value, controlling the auxiliary braking system to brake according to the total braking force requirement value;

[0008] When the total braking force requirement value is greater than the maximum auxiliary braking force value, the auxiliary braking system is controlled to brake according to the maximum auxiliary braking force value, and the main braking system is controlled to brake according to the difference between the total braking force requirement value and the maximum auxiliary braking force value.

[0009] Furthermore, the braking method further comprises:

[0010] When the working mode is the gliding mode, the total braking force requirement value of the vehicle is calculated according to the current operating condition of the vehicle; and the auxiliary braking system is controlled to brake according to the total braking force requirement value.

[0011] Furthermore, the braking method further comprises:

[0012] When the working mode is the constant speed downhill mode, the total braking force requirement value of the vehicle is calculated according to the current operating condition of the vehicle; and the auxiliary braking system is controlled to brake according to the total braking force requirement value.

[0013] Further, the auxiliary braking system includes a motor, an engine and a retarder;

[0014] The maximum auxiliary braking force value is the maximum value of the motor braking force value that the motor can provide, the engine braking force value that the engine can provide, and the retarder braking force value that the retarder can provide, or is the sum of the motor braking force value, the engine braking force value, and the retarder braking force value.

[0015] Further, when the maximum auxiliary braking force value is the sum of the motor braking force value, the engine braking force value and the retarder braking force value, the step of controlling the auxiliary braking system to brake according to the total braking force demand value or the step of controlling the auxiliary braking system to brake according to the maximum auxiliary braking force value includes:

[0016] Controlling the motor to brake according to the motor force value, controlling the retarder to brake according to the retarder braking force value, and controlling the engine to brake according to the engine braking force value;

[0017] or,

[0018] When the total braking force requirement value is not greater than the motor braking force value, controlling the motor to brake according to the total braking force requirement value;

[0019] When the total braking force demand value is greater than the motor braking force value, controlling the motor to brake according to the motor braking force value, and controlling the retarder to brake according to the retarder braking force value;

[0020] When the total braking force requirement value is greater than the sum of the motor braking force value and the retarder braking force value, the motor is controlled to brake according to the motor braking force value, the retarder is controlled to brake according to the retarder braking force value, the engine is controlled to brake according to the engine braking force value or to brake according to the difference between the total braking force requirement value, the motor braking force value and the retarder braking force value.

[0021] Furthermore, the step of controlling the motor to brake according to the motor force value includes:

[0022] Control the motor to output negative torque for braking according to the motor force value;

[0023] or,

[0024] The recovery torque is calculated according to the motor motive force value, and the motor is controlled to recover the kinetic energy of the vehicle according to the recovery torque to charge the power battery until the power of the power battery reaches an upper power limit.

[0025] Further, the current operating condition includes a first operating condition, or includes a first operating condition and a second operating condition, the first operating condition includes a current vehicle weight and a current vehicle speed, and the second operating condition includes a current brake pedal opening;

[0026] The step of calculating the total braking force requirement value of the vehicle according to the current operating condition of the vehicle comprises:

[0027] Calculating a total braking force requirement value of the vehicle according to a first operating condition of the vehicle;

[0028] or,

[0029] Calculating a total braking force requirement value of the vehicle according to a first operating condition and a second operating condition of the vehicle;

[0030] The step of calculating the maximum auxiliary braking force value that can be provided by the auxiliary braking system according to the current operating condition of the vehicle comprises:

[0031] Calculating the motor power value that can be provided by the motor according to the state of the power battery and the state of the motor, wherein the state of the power battery includes the upper limit value and the remaining power of the power battery, and the state of the motor includes the working state and motor parameters of the motor;

[0032] Calculating a retarder braking force value that can be provided by the retarder according to the state of the retarder, wherein the state of the retarder includes a working state of the retarder and retarder parameters;

[0033] Calculating an engine braking force value that can be provided by the engine according to the state of the engine, wherein the state of the engine includes an engine operating state and engine parameters;

[0034] The maximum auxiliary braking force value that can be provided by the auxiliary braking system is calculated according to the motor force value, the retarder braking force value and the engine braking force value.

[0035] Furthermore, before the step in which the working mode is the braking mode, the braking method further includes:

[0036] Real-time detection of the accelerator pedal opening, brake pedal opening and first switch state of the vehicle;

[0037] When the accelerator pedal opening is zero and the brake pedal opening is not zero, the working mode is controlled to switch to the braking mode; when the accelerator pedal opening is zero, the brake pedal opening is zero and the first switch state is closed, the working mode is controlled to switch to the gliding mode; when the accelerator pedal opening is zero, the brake pedal opening is zero and the first switch state is open, the working mode is controlled to switch to the constant speed downhill mode.

[0038] Compared with the prior art, the present invention has the following advantages:

[0039] The braking method for commercial vehicles of the present invention calculates the total braking force demand value of the vehicle and the maximum auxiliary braking force value that can be provided by the auxiliary braking system according to the current operating conditions of the vehicle in the braking mode, and then preferentially starts the auxiliary braking system for braking through comparison and judgment, and only when the total braking force demand value is greater than the maximum auxiliary braking force value, the main braking system is started to brake according to the difference between the total braking force demand value and the maximum auxiliary braking force value, thereby maximizing the braking effect of the auxiliary braking system, and while being able to fully recover the braking energy of the vehicle, the braking burden of the main braking system can be reduced, which is beneficial to improving the braking effect of the vehicle.

[0040] In addition, by setting the gliding mode and the constant speed descent mode, in these two modes, the auxiliary braking system is controlled to brake according to the total braking force demand value, which can further reduce the friction loss caused by the main braking system participating in braking and further improve the energy recovery effect of the vehicle; feedback braking is performed in the order of priority of the motor, retarder and engine to provide auxiliary braking force, which can make full use of the electric energy recovery performance of the motor and retarder, thereby further improving the energy recovery efficiency of the braking system.

[0041] Another object of the present invention is to provide a braking system, comprising a control unit, a main braking system and an auxiliary braking system; the control unit obtains the vehicle's accelerator pedal opening, brake pedal opening, and current operating conditions of the vehicle, and controls the main braking system and the auxiliary braking system to brake according to the commercial vehicle braking method described in the present invention.

[0042] At the same time, the present invention also proposes a commercial vehicle, on which the above-mentioned braking system is provided. The braking system and commercial vehicle of the present invention have the technical advantages possessed by the above-mentioned braking method for commercial vehicles. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The accompanying drawings, which constitute part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention. The directional terms such as front and back, up and down, etc. involved therein are only used to indicate relative positional relationships and do not constitute improper limitations on the present invention. In the accompanying drawings:

[0044] Figure 1 This is a schematic diagram of the overall control flow of the braking method for a commercial vehicle according to Embodiment 1 of the present invention;

[0045] Figure 2 This is a schematic diagram of a control flow in a braking mode in a braking method according to Embodiment 1 of the present invention;

[0046] Figure 3 This is a schematic diagram of the control flow in the gliding mode in the braking method according to the first embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of the control flow in the constant speed downhill mode in the braking method according to the first embodiment of the present invention;

[0048] Figure 5 Schematic diagram of the system structure of the braking system described in the second embodiment of the present invention.

[0049] Description of reference numerals:

[0050] 1. Control unit; 10. Vehicle controller; 11. Braking system controller; 12. Engine controller; 13. Retarder controller; 14. Motor controller; 15. Battery management system;

[0051] 20. Main braking system; 22. Engine; 23. Retarder; 24. Motor; 25. Power battery. DETAILED DESCRIPTION

[0052] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0053] In the description of the present invention, unless otherwise clearly defined, the terms "installed", "connected", "connection", and "connector" should be understood in a broad sense. For example, the connection can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, an indirect connection through an intermediate medium, or a communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in combination with specific circumstances.

[0054] In addition, in the embodiments and drawings of the present invention, there may be a situation where the English abbreviations of various control components are used to represent the corresponding control components. The possible English abbreviations and their meanings are listed in detail as follows:

[0055] EBS (Electronic Brake Systems), electronic brake system, also refers to the electronic brake system controller;

[0056] ECU (Electronic Control Unit), electronic control unit, also refers to the engine controller;

[0057] MCU (Micro Control Unit), micro control unit, also refers to the motor controller;

[0058] BMS (Battery Management System), battery management system;

[0059] VCU (Vehicle Control Unit), vehicle control unit.

[0060] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0061] Embodiment 1

[0062] This embodiment relates to a braking method for a commercial vehicle, which is used to control the braking force output of the vehicle's braking system, and can improve the braking effect of the vehicle; an exemplary control process is as follows: Figure 1 , Figure 2 and Figure 3 shown.

[0063] In general, the braking method includes:

[0064] When the working mode is the braking mode, the total braking force requirement of the vehicle and the maximum auxiliary braking force value that the auxiliary braking system can provide are calculated according to the current operating conditions of the vehicle;

[0065] When the total braking force demand value is not greater than the maximum auxiliary braking force value, the auxiliary braking system is controlled to brake according to the total braking force demand value;

[0066] When the total braking force requirement value is greater than the maximum auxiliary braking force value, the auxiliary braking system is controlled to brake according to the maximum auxiliary braking force value, and the main braking system is controlled to brake according to the difference between the total braking force requirement value and the maximum auxiliary braking force value.

[0067] In addition to the above braking modes, the braking method of this embodiment also includes a gliding mode and a constant speed downhill mode; the following braking control strategies are adopted in the above two modes:

[0068] When the working mode is the coasting mode, the total braking force requirement of the vehicle is calculated according to the current operating condition of the vehicle; and the auxiliary braking system is controlled to brake according to the total braking force requirement.

[0069] When the working mode is the constant speed downhill mode, the total braking force requirement of the vehicle is calculated according to the current operating condition of the vehicle; and the auxiliary braking system is controlled to brake according to the total braking force requirement.

[0070] There are of course a variety of methods for switching between the three working modes mentioned above; for example, manual selection; or the vehicle's control system automatically determines and completes the switching between modes based on the driver's operation and the vehicle's driving status.

[0071] like Figure 1 As shown, in this embodiment, before the step in which the working mode is the braking mode, the braking method further includes the following steps:

[0072] Real-time detection of the vehicle's accelerator pedal opening, brake pedal opening and first switch state;

[0073] When the accelerator pedal opening is zero and the brake pedal opening is not zero, the control working mode is switched to the braking mode;

[0074] When the accelerator pedal opening is zero, the brake pedal opening is zero and the first switch state is closed, the control working mode is switched to the gliding mode;

[0075] When the accelerator pedal opening is zero, the brake pedal opening is zero and the first switch state is on, the control working mode is switched to the constant speed downhill mode.

[0076] The first switch mentioned above can be a specially set fixed speed downhill switch, and the driver can change its closed and opened state by manipulating the fixed speed downhill switch. By setting the gliding mode and the fixed speed downhill mode, the auxiliary brake system is controlled to brake according to the total braking force demand value in these two modes, which can further reduce the friction loss caused by the main brake system participating in the braking, and further improve the energy recovery effect of the vehicle.

[0077] Specifically, the control strategy of the constant speed downhill mode of this embodiment is as follows: Figure 4 As shown, when the accelerator pedal opening is zero and the brake pedal opening is zero, the vehicle enters the constant speed downhill mode when the constant speed downhill command issued by the first switch being turned on is received. In the constant speed downhill mode, the preset constant speed value is used as the control target value, and the size of the auxiliary braking force provided by the motor 24, the engine 22 and the retarder 23 is regulated by closed-loop control, and the braking feedback strength of the motor 24, the retarder 23 and the engine 22 is regulated in real time. The setting of the constant speed downhill mode can not only enable the vehicle to cope with the road conditions of long-distance downhill driving well and ensure the stable speed of the vehicle when going downhill, but also can recover energy to the greatest extent, thereby further improving the energy recovery performance of the vehicle.

[0078] The constant speed downhill command is issued by the constant speed downhill switch, and the constant speed value preferably adopts the vehicle speed value when the constant speed downhill mode is turned on. By setting the constant speed downhill switch, the operation is simple, the working mode switching of the braking system can be flexibly controlled by humans, and the appropriate vehicle speed value can be flexibly selected as the target value of the constant speed control during the downhill process.

[0079] Based on the above settings, combined with Figure 2 , Figure 3 and Figure 4 It can be seen that the priority order of providing braking force is: motor 24, retarder 23, engine 22 and air brake of main brake system 20. Figure 3 As shown in , in the gliding mode, when the braking components in the auxiliary braking system can no longer meet the braking needs of the vehicle, the driver can step on the brake pedal to intervene in the main braking system 20; Figure 4 As shown in , in the constant speed downhill mode, when the braking components in the auxiliary braking system can no longer meet the braking needs of the vehicle, the driver can also step on the brake pedal to intervene in the main braking system 20 to ensure driving safety.

[0080] In specific implementation, the main brake system 20 of this embodiment is an air brake system based on the EBS system; the auxiliary brake system includes a combination of three types of feedback brakes, namely, the motor 24, the retarder 23 and the engine 22. Among them, the retarder 23 and the engine 22 can issue a shielding instruction through an external operating switch. Preferably, in addition to the constant speed downhill mode, when the vehicle has an external operating switch and the switch is turned off (shielding instruction is issued), the retarder 23 and the engine 22 do not participate in the auxiliary braking, otherwise they are automatically controlled by the control program.

[0081] Of course, in braking mode and gliding mode, the vehicle is in a deceleration process. Regardless of whether the main braking system is involved in the braking process, when the vehicle stops, the air brake of the main braking system is required to participate in the final braking to stop the vehicle.

[0082] It should be pointed out that the braking method of the present invention is applicable to various types of vehicles, especially heavy commercial vehicles. With the development of new energy technologies, in new energy heavy commercial vehicles, hybrid-based commercial vehicles are equipped with drive motors, which can play an auxiliary braking role through motor feedback; at the same time, such heavy commercial traction vehicles will be equipped with retarders or other auxiliary braking devices, and the prior art lacks good technical solutions for auxiliary braking devices for heavy vehicles. The braking method of the present invention solves the above problems well.

[0083] The various brake components in the auxiliary brake system certainly have various types and configurations. The retarder 23 of the present embodiment can be an electric turbine retarder or a hydraulic retarder; the brake of the engine 22 can be one of an exhaust butterfly valve brake, a deflation brake, and a compression release brake.

[0084] In this embodiment, the vehicle's braking system includes a main braking system 20 in which the main braking force is provided by air brakes; the auxiliary braking system can be composed of at least one of a motor 24, an engine 22 and a retarder 23, and the motor 24, the engine 22 and the retarder 23 can provide auxiliary braking force separately or jointly through feedback.

[0085] like Figure 3 As shown, in order to improve the flexibility of active control of various components in the auxiliary braking system, control switches such as a retarder switch and an engine brake switch that can issue a shielding command can be configured on the vehicle; in this way, the auxiliary braking system of the vehicle can be configured differently according to actual working conditions (such as different configurations such as motor 24+retarder 23+engine 22, motor 24+retarder 23, motor 24+engine 22, etc.).

[0086] In addition, the braking method of this embodiment also includes a shielding instruction for prohibiting the engine 22 and the retarder 23 from providing auxiliary braking force; when the shielding instruction exists, if the main braking force provided by the main braking system 20 cannot meet the difference requirement, a warning is issued.

[0087] Under this configuration condition, if certain working conditions require increasing the auxiliary braking force, but the driver forgets to turn on the retarder switch and the engine brake switch, the main brake system 20 may work for a long time and cause the air brake (mechanical brake) to overheat and cause decay. When this happens, a warning can be issued to manually open the relevant control switch to turn off the shielding instruction, or the working condition can be automatically identified to start the auxiliary braking function of the retarder 23 and the engine 22 to prevent the air brake from overheating and causing decay.

[0088] When the motor 24, the engine 22 and the retarder 23 are respectively used as the above-mentioned auxiliary braking system, for the maximum auxiliary braking force value that can be provided by the auxiliary braking system, the maximum auxiliary braking force value is the maximum value of the motor braking force value that can be provided by the motor 24, the engine braking force value that can be provided by the engine 22 and the retarder braking force value that can be provided by the retarder 23.

[0089] In the case where the auxiliary braking system is composed of the motor 24, the engine 22 and the retarder 23, the maximum auxiliary braking force value is the sum of the motor braking force value, the engine braking force value and the retarder braking force value.

[0090] When the motor 24, the engine 22 and the retarder 23 together form an auxiliary braking system, there are of course multiple arrangements of the braking participation priority of each component in the auxiliary braking system. In this embodiment, when the maximum auxiliary braking force value is the sum of the motor braking force value, the engine braking force value and the retarder braking force value, the step of controlling the auxiliary braking system to brake according to the total braking force demand value or the step of controlling the auxiliary braking system to brake according to the maximum auxiliary braking force value includes the following two optional strategies:

[0091] Strategy 1: Control the motor 24 to brake according to the motor braking force value, control the retarder 23 to brake according to the retarder braking force value, and control the engine 22 to brake according to the engine braking force value.

[0092] Strategy 2:

[0093] When the total braking force demand value is not greater than the motor braking force value, the motor 24 is controlled to brake according to the total braking force demand value;

[0094] When the total braking force demand value is greater than the motor braking force value, the motor 24 is controlled to brake according to the motor braking force value, and the retarder 23 is controlled to brake according to the retarder braking force value;

[0095] When the total braking force demand value is greater than the sum of the motor braking force value and the retarder braking force value, the control motor 24 is controlled to brake according to the motor braking force value, the control retarder 23 is controlled to brake according to the retarder braking force value, and the control engine 22 is controlled to brake according to the engine braking force value or according to the difference between the total braking force demand value, the motor braking force value and the retarder braking force value.

[0096] Specifically, if Figure 2 As shown, in the braking mode, the present embodiment distributes the auxiliary braking force among the motor 24, the engine 22 and the retarder 23 according to the set distribution principle. In the present embodiment, the distribution principle includes: the provision of the auxiliary braking force is preferentially distributed in the order of the motor 24, the retarder 23 and the engine 22. Feedback braking is performed in the order of priority of the motor 24, the retarder 23 and the engine 22 to provide the auxiliary braking force, which can make full use of the electric energy recovery performance of the motor 24 and the retarder 23, thereby further improving the energy recovery efficiency of the braking system.

[0097] When controlling the motor 24 to brake according to the motor force value, the following two control methods can be selectively adopted:

[0098] Method 1: Control the motor 24 to output negative torque for braking according to the motor force value;

[0099] Method 2: Calculate the recovery torque according to the motor force value, and control the motor 24 to recover the kinetic energy of the vehicle according to the recovery torque to charge the power battery until the power of the power battery reaches the upper limit of the power.

[0100] Since the vehicle's power battery has limited power, in scenarios such as going down a long slope or on mountain roads, once the battery power reaches the recovery limit, the motor will no longer be able to provide feedback in the second method described above, and thus the braking effect cannot be exerted through motor feedback; at this time, the motor 24 can be stopped from participating in braking, or the motor 24 can be controlled to brake in the first method described above.

[0101] When calculating the total braking force demand value of the vehicle and the maximum auxiliary braking force value that the auxiliary braking system can provide, relevant data of the vehicle's current operating conditions should be obtained first. The data of the current operating conditions may include the power of the power battery 25, the current vehicle speed, the current vehicle weight, and the status data and parameters of the engine 22, retarder 23 and motor 24.

[0102] In this embodiment, the current operating condition includes a first operating condition, or includes a first operating condition and a second operating condition, wherein the first operating condition includes a current vehicle weight and a current vehicle speed, and the second operating condition includes a current brake pedal opening.

[0103] The total braking force requirement of the vehicle can be calculated using any of the following methods:

[0104] Method 1: Calculate the total braking force requirement of the vehicle according to the first operating condition of the vehicle.

[0105] Method 2: Calculate the total braking force requirement of the vehicle according to the first operating condition and the second operating condition of the vehicle.

[0106] In the coasting mode, the above method 1 can be used for calculation. According to the current vehicle weight and current vehicle speed, based on the mechanical acceleration formula, the braking force required to reduce the vehicle speed from the current vehicle speed to 0 speed within the set coasting time can be calculated, thereby obtaining the total braking force demand value. For example, if the current vehicle weight is T, the current vehicle speed is v, and the set coasting time is t, the total braking force demand value can be estimated using the following formula:

[0107] Total braking force requirement = Tv / t.

[0108] In the constant speed downhill mode, the total braking force required to maintain the current speed can be calculated based on the current vehicle weight and speed, as well as the vehicle's downhill acceleration; and Figure 4 The control steps shown enable the motor 24, the retarder 23 and the engine 22 to participate in braking in sequence.

[0109] Specifically,

[0110] The following steps can be used to calculate the maximum auxiliary braking force that the auxiliary braking system can provide:

[0111] Step 1: Calculate the motor power value that the motor 24 can provide according to the state of the power battery and the state of the motor 24. The state of the power battery includes the upper limit value and remaining power of the power battery, and the state of the motor 24 includes the working state and motor parameters of the motor.

[0112] Step 2: Calculate the retarder braking force value that can be provided by the retarder 23 according to the state of the retarder 23 . The state of the retarder 23 includes the working state of the retarder 23 and the retarder parameters.

[0113] Step 3: Calculate the engine braking force value that can be provided by the engine 22 according to the state of the engine 22, where the state of the engine 22 includes the working state of the engine and the engine parameters;

[0114] Step 4: Calculate the maximum auxiliary braking force value that the auxiliary braking system can provide based on the motor braking force value, the retarder braking force value and the engine braking force value.

[0115] The working state of the motor 24 includes determining whether the function of the motor 24 to charge the power battery is available. When the charging function is available, the charging power of the motor 24 is calculated according to the parameters of the motor 24, and then the motor kinetic force value is calculated. Alternatively, the working state of the motor 24 may also be determining whether the function of the motor 24 to output negative torque is available. When the function of outputting negative torque is available, the magnitude of the negative torque is calculated according to the parameters of the motor 24, and then the motor kinetic force value is obtained.

[0116] Similarly, the retarder braking force value can be obtained through calculation based on the working state of the retarder 23 and the retarder parameters, and the engine braking force value can be obtained through calculation based on the working state of the engine 22 and the engine parameters.

[0117] In addition, in the braking mode, when the main braking system 20 is started, the magnitude of the main braking force provided by the main braking system 20 is determined by the difference between the total braking force demand value and the auxiliary braking force. By obtaining the power of the power battery 25, the current vehicle speed, the state data of the engine 22, the retarder 23 and the motor 24, the magnitude of the auxiliary braking force that can be provided by the auxiliary braking system can be estimated. The part of the auxiliary braking force that is insufficient for the total braking force demand value is all provided by the air brake of the main braking system 20, which can just meet the braking demand of the vehicle, so that the vehicle has a good braking effect. At the same time, it should be pointed out that the control parameters of the engine 22, the retarder 23 and the motor 24 in the auxiliary braking system, such as the feedback force, the retarding force, etc., are all calibrable; by setting the necessary correction algorithm in the method, the relevant parameters are continuously calibrated and corrected during use, and the magnitude of the auxiliary braking force that can be provided by the feedback of the engine 22, the retarder 23 and the motor 24 can be accurately estimated.

[0118] To sum up, the braking method for commercial vehicles of this embodiment calculates the total braking force demand value of the vehicle and the maximum auxiliary braking force value that the auxiliary braking system can provide according to the current operating conditions of the vehicle in the braking mode, and then, through comparison and judgment, preferentially starts the auxiliary braking system for braking, and only when the total braking force demand value is greater than the maximum auxiliary braking force value, starts the main braking system for braking according to the difference between the total braking force demand value and the maximum auxiliary braking force value, thereby maximizing the braking effect of the auxiliary braking system, and can fully recover the braking energy of the vehicle while reducing the braking burden of the main braking system, which is beneficial to improving the braking effect of the vehicle.

[0119] Moreover, in the auxiliary braking system, the feedback from the motor 24, the engine 22 and the retarder 23 provides auxiliary braking force, and energy recovery is performed; in the gliding mode, the auxiliary braking system is started first, with the motor 24 as priority, and the retarder 23 and the engine 22 as supplements, so as to maximize the recovery of energy and replenish electricity to the power battery 25, which is beneficial to improving the energy recovery efficiency of the vehicle.

[0120] Embodiment 2

[0121] This embodiment relates to a braking system and a commercial vehicle equipped with the braking system. The braking system includes a control unit 1, a main braking system 20 and an auxiliary braking system; the control unit 1 is used to obtain status signals of the accelerator pedal, the brake pedal, the power battery 25 and the vehicle operating conditions, and control the braking force output of the main braking system 20 and the auxiliary braking system according to the braking method of the commercial vehicle provided in the first embodiment. An exemplary configuration of the braking system of this embodiment is as follows Figure 5 shown.

[0122] Specifically, the auxiliary braking system includes a motor 24, an engine 22 and a retarder 23, and the control unit 1 includes a motor controller 14 for controlling the regenerative braking of the motor 24, an engine controller 12 for controlling the regenerative braking of the engine 22, and a retarder controller 13 for controlling the regenerative braking of the retarder 23. The braking system controller 11, the engine controller 12, the retarder controller 13, the motor controller 14 and the battery management system 15 are all connected to the vehicle controller 10.

[0123] By adopting the above-mentioned configuration architecture, the existing control elements on the vehicle are fully utilized. The vehicle controller 10, the braking system controller 11, the engine controller 12, the retarder controller 13, the motor controller 14 and the battery management system 15 together constitute the control unit 1 of the braking system. Various data of the vehicle operating conditions can be exchanged with each other through communication between the control elements, and the braking actions of the main braking system 20 and the auxiliary braking system can be coordinated and controlled, so as to well complete the control strategy of the braking method of Example 1, so as to achieve the purpose of improving the vehicle energy recovery performance.

[0124] The braking system and the braking method used in this embodiment are particularly suitable for hybrid heavy-duty commercial vehicles, which can effectively extend the life of the main braking system, and can also recover energy to the maximum extent, thereby improving the economy of the entire vehicle. Moreover, the components involved in the braking system are all mature components, which are convenient for technical implementation and rapid application. By adopting the braking system and the braking method of this embodiment, not only can the efficiency of energy recovery be improved, but also the braking effect and safe driving performance of the vehicle can be improved.

[0125] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A braking method for a commercial vehicle, characterized in that: include: When the working mode is the braking mode, the total braking force requirement of the vehicle and the maximum auxiliary braking force value that the auxiliary braking system can provide are calculated according to the current operating conditions of the vehicle; When the total braking force requirement value is not greater than the maximum auxiliary braking force value, controlling the auxiliary braking system to brake according to the total braking force requirement value; When the total braking force requirement value is greater than the maximum auxiliary braking force value, the auxiliary braking system is controlled to brake according to the maximum auxiliary braking force value, and the main braking system is controlled to brake according to the difference between the total braking force requirement value and the maximum auxiliary braking force value.

2. The commercial vehicle braking method according to claim 1, characterized in that: The braking method further comprises: When the working mode is the coasting mode, calculating the total braking force requirement value of the vehicle according to the current operating condition of the vehicle; The auxiliary brake system is controlled to perform braking according to the total braking force requirement value.

3. The commercial vehicle braking method according to claim 1, characterized in that: The braking method further comprises: When the working mode is a constant speed downhill mode, calculating a total braking force requirement value of the vehicle according to the current operating condition of the vehicle; The auxiliary brake system is controlled to perform braking according to the total braking force requirement value.

4. The commercial vehicle braking method according to any one of claims 1 to 3, characterized in that: The auxiliary braking system comprises a motor (24), an engine (22) and a retarder (23); The maximum auxiliary braking force value is the maximum value of the motor braking force value that can be provided by the motor (24), the engine braking force value that can be provided by the engine (22), and the retarder braking force value that can be provided by the retarder (23), or is the sum of the motor braking force value, the engine braking force value, and the retarder braking force value.

5. The commercial vehicle braking method according to claim 4, characterized in that: When the maximum auxiliary braking force value is the sum of the motor braking force value, the engine braking force value and the retarder braking force value, the step of controlling the auxiliary braking system to brake according to the total braking force demand value or the step of controlling the auxiliary braking system to brake according to the maximum auxiliary braking force value includes: Controlling the motor (24) to brake according to the motor force value, controlling the retarder (23) to brake according to the retarder braking force value, and controlling the engine (22) to brake according to the engine braking force value; or, When the total braking force requirement value is not greater than the motor braking force value, controlling the motor (24) to brake according to the total braking force requirement value; When the total braking force demand value is greater than the motor braking force value, controlling the motor (24) to brake according to the motor braking force value, and controlling the retarder (23) to brake according to the retarder braking force value; When the total braking force requirement value is greater than the sum of the motor braking force value and the retarder braking force value, the motor (24) is controlled to brake according to the motor braking force value, the retarder (23) is controlled to brake according to the retarder braking force value, and the engine (22) is controlled to brake according to the engine braking force value or to brake according to the difference between the total braking force requirement value, the motor braking force value and the retarder braking force value.

6. The commercial vehicle braking method according to claim 5, characterized in that: The step of controlling the motor (24) to brake according to the motor braking force value comprises: Controlling the motor (24) to output negative torque for braking according to the motor force value; or, The recovery torque is calculated according to the motor motive force value, and the motor (24) is controlled to recover the kinetic energy of the vehicle according to the recovery torque to charge the power battery until the power of the power battery reaches an upper power limit.

7. The commercial vehicle braking method according to claim 4, characterized in that: The current operating condition includes a first operating condition, or includes a first operating condition and a second operating condition, wherein the first operating condition includes a current vehicle weight and a current vehicle speed, and the second operating condition includes a current brake pedal opening; The step of calculating the total braking force requirement value of the vehicle according to the current operating condition of the vehicle comprises: Calculating a total braking force requirement value of the vehicle according to a first operating condition of the vehicle; or, Calculating a total braking force requirement value of the vehicle according to a first operating condition and a second operating condition of the vehicle; The step of calculating the maximum auxiliary braking force value that can be provided by the auxiliary braking system according to the current operating condition of the vehicle comprises: Calculating the motor power value that can be provided by the motor (24) according to the state of the power battery and the state of the motor (24), wherein the state of the power battery includes the upper limit value and the remaining power of the power battery, and the state of the motor (24) includes the working state and motor parameters of the motor; Calculating a retarder braking force value that can be provided by the retarder (23) according to the state of the retarder (23), wherein the state of the retarder (23) includes a working state of the retarder (23) and retarder parameters; Calculating an engine braking force value that can be provided by the engine (22) according to a state of the engine (22), wherein the state of the engine (22) includes an engine operating state and engine parameters; The maximum auxiliary braking force value that can be provided by the auxiliary braking system is calculated according to the motor force value, the retarder braking force value and the engine braking force value.

8. The commercial vehicle braking method according to claim 1, characterized in that: Before the step in which the working mode is the braking mode, the braking method further includes: Real-time detection of the accelerator pedal opening, brake pedal opening and first switch state of the vehicle; When the accelerator pedal opening is zero and the brake pedal opening is not zero, controlling the working mode to switch to the braking mode; When the accelerator pedal opening is zero, the brake pedal opening is zero and the first switch state is closed, controlling the working mode to switch to the gliding mode; When the accelerator pedal opening is zero, the brake pedal opening is zero, and the first switch state is on, the working mode is controlled to switch to a constant speed downhill mode.

9. A braking system, characterized in that: It comprises a control unit (1), a main braking system (20) and an auxiliary braking system; The control unit (1) obtains the accelerator pedal opening, brake pedal opening, and current operating condition of the vehicle, and controls the main braking system (20) and the auxiliary braking system to brake according to the braking method for a commercial vehicle according to any one of claims 1 to 8.

10. A commercial vehicle, characterized in that: The commercial vehicle is provided with the brake system according to claim 9.

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