Vehicle speed control method, device, equipment and readable storage medium

Abstract

The present invention provides a vehicle speed control method, device, equipment and readable storage medium, the method comprising: if the opening value of the vehicle brake pedal changes from large to small, and when the opening value is less than a first threshold, the vehicle speed is collected and set as the target speed; when the first speed difference between the actual vehicle speed and the target speed is greater than a second threshold, the target braking torque of the retarder is determined according to the target speed; auxiliary braking is performed according to the target braking torque of the retarder to control the vehicle speed. Through the present invention, during the vehicle braking process, there is no need to add other electronic control logic or sensors to the braking system, and auxiliary braking only needs to be performed through the braking torque of the retarder to achieve vehicle speed control and avoid wear on the brake shoe.

Description

Technical Field

[0001] The present invention relates to the field of automobile technology, and in particular to a vehicle speed control method, device, equipment and a readable storage medium. Background Art

[0002] When the vehicle is going downhill, it is necessary to slow down or drive at a constant speed. The conventional method is to generate braking force through brake friction. However, this braking method also has its shortcomings. The brakes can easily generate high temperatures due to long-term use, resulting in brake failure and vehicle brake failure. In order to prevent excessive brake involvement, the electronically controlled brake EBS or the EBI function in ESC (brake system and retarder integrated) are also used to integrate the auxiliary braking function with the conventional braking function. Because the hydraulic auxiliary brake intervenes gently, the downhill braking process is more comfortable, while protecting the service brakes and reducing shoe wear.

[0003] However, in the braking method combining the auxiliary braking function with the conventional braking function, in addition to the braking system itself, other electronic control logic or sensors are added during the vehicle braking process, and wear on the shoe is inevitable. Summary of the invention

[0004] The main purpose of the present invention is to provide a vehicle speed control method, device, equipment and readable storage medium, aiming at achieving vehicle speed control and avoiding wear on brake shoes by using the braking torque of the retarder during vehicle braking without adding other electronic control logic or sensors to the braking system.

[0005] In a first aspect, the present invention provides a vehicle speed control method, the vehicle speed control method comprising:

[0006] If the opening value of the vehicle brake pedal changes from large to small, and when the opening value is less than a first threshold, the vehicle speed is collected and set as the target speed;

[0007] When a first speed difference between the actual vehicle speed and the target vehicle speed is greater than a second threshold, determining a target braking torque of the retarder according to the target vehicle speed;

[0008] Auxiliary braking is performed according to the target braking torque of the retarder to control the vehicle speed.

[0009] Optionally, the step of determining a target braking torque of the retarder according to the target vehicle speed includes:

[0010] Substituting the target vehicle speed into the first formula, the first formula is:

[0011]

[0012] Wherein, a', b', c', d', e', f', g', h' and i' are constants; V0 is the target speed; m is the weight of the vehicle; g is the acceleration due to gravity; is the slope angle; n e is the engine speed; i e is the gearbox ratio;

[0013] Substituting the target vehicle speed into the second formula, the second formula is:

[0014]

[0015] Where, j' is a constant; r is the tire radius; i0 is the drive axle speed ratio;

[0016] Solve the first and second formulas together to get n e 、i e Multiple solutions of ;

[0017] Substituting multiple groups of solutions into the third formula respectively, the braking torque of multiple retarders is obtained. The third formula is:

[0018]

[0019] Among them, T he is the braking torque of the retarder;

[0020] With the maximum T he is the target braking torque of the retarder.

[0021] Optionally, the step of performing auxiliary braking according to the target braking torque of the retarder to control the vehicle speed includes:

[0022] Determining a target engine speed and a target gearbox speed ratio according to a target braking torque of the retarder;

[0023] Determining a target transmission shaft speed according to the target engine speed and the target gearbox speed ratio;

[0024] According to the target transmission shaft speed, the engine is controlled to reach the target engine speed, and the transmission is controlled to reach the target transmission speed ratio, so as to control the vehicle speed.

[0025] Optionally, after the step of determining a target engine speed and a target gearbox speed ratio according to the target braking torque of the retarder, the method further comprises:

[0026] detecting whether the target engine speed is greater than a third threshold;

[0027] If the target engine speed is not greater than the third threshold, the step of determining the target transmission shaft speed according to the target engine speed and the target gearbox speed ratio is performed;

[0028] If the target engine speed is greater than a third threshold, an alarm is output.

[0029] Optionally, after the step of performing auxiliary braking according to the target braking torque of the retarder to control the vehicle speed, the method further includes:

[0030] Determining a theoretical deceleration time according to the actual vehicle speed, the target vehicle speed, the target engine speed and the target gearbox speed ratio;

[0031] Adding a preset time to the theoretical deceleration time to obtain a target deceleration time;

[0032] When the control time reaches the target deceleration time, obtaining a new actual vehicle speed, and detecting whether a second speed difference between the new actual vehicle speed and the target vehicle speed is less than a fourth threshold, wherein the control time is the time for performing auxiliary braking;

[0033] If the second speed difference is not less than a fourth threshold value, the step of performing auxiliary braking according to the target braking torque of the retarder is suspended, and an alarm is output.

[0034] Optionally, after the step of performing auxiliary braking according to the target braking torque of the retarder to control the vehicle speed, the method further includes:

[0035] Collect the temperature of the retarder;

[0036] detecting whether the temperature of the retarder is greater than a fifth threshold;

[0037] If the temperature of the retarder is greater than a fifth threshold, the step of performing auxiliary braking according to the target braking torque of the retarder is suspended, and an alarm is output.

[0038] In a second aspect, the present invention further provides a vehicle speed control device, the vehicle speed control device comprising:

[0039] A first determination module is used to collect the vehicle speed and set it as the target speed if the opening value of the vehicle brake pedal changes from large to small and when the opening value is less than a first threshold;

[0040] A second determination module, configured to determine a target braking torque of the retarder according to the target vehicle speed when a first speed difference between the actual vehicle speed and the target vehicle speed is greater than a second threshold;

[0041] The control module is used to perform auxiliary braking according to the target braking torque of the retarder to control the vehicle speed.

[0042] In a third aspect, the present invention also provides a vehicle speed control device, comprising a processor, a memory, and a vehicle speed control program stored in the memory and executable by the processor, wherein when the vehicle speed control program is executed by the processor, the steps of the vehicle speed control method as described above are implemented.

[0043] In a fourth aspect, the present invention further provides a readable storage medium, on which a vehicle speed control program is stored, wherein when the vehicle speed control program is executed by a processor, the steps of the vehicle speed control method as described above are implemented.

[0044] In the present invention, if the opening value of the vehicle brake pedal changes from large to small, and when the opening value is less than a first threshold, the vehicle speed is collected and set as the target speed; when the first speed difference between the actual vehicle speed and the target speed is greater than a second threshold, the target braking torque of the retarder is determined according to the target speed; auxiliary braking is performed according to the target braking torque of the retarder to control the vehicle speed. Through the present invention, during the vehicle braking process, there is no need to add other electronic control logic or sensors to the braking system, and auxiliary braking only needs to be performed through the braking torque of the retarder to achieve vehicle speed control and avoid wear on the brake shoe. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a flow chart of a first embodiment of a vehicle speed control method of the present invention;

[0046] Figure 2 It is a schematic diagram of a curve showing the relationship between the braking torque and the transmission shaft speed of a test retarder in one embodiment of the present invention;

[0047] Figure 3 A schematic diagram of a flow chart of auxiliary braking according to the target braking torque of the retarder in one embodiment of the present invention

[0048] Figure 4 It is a flow chart of a second embodiment of a vehicle speed control method of the present invention;

[0049] Figure 5 It is a schematic diagram of the functional modules of the vehicle speed control device involved in the embodiment of the present invention;

[0050] Figure 6 It is a schematic diagram of the hardware structure of the vehicle speed control device involved in the embodiment of the present invention.

[0051] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0052] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0053] In a first aspect, an embodiment of the present invention provides a vehicle speed control method.

[0054] Reference Figure 1 , Figure 1 FIG. 1 is a flow chart of the first embodiment of the vehicle speed control method of the present invention. Figure 1 As shown, in one embodiment, the vehicle speed control method includes:

[0055] Step S10, if the opening value of the vehicle brake pedal changes from large to small, and when the opening value is less than a first threshold, the vehicle speed is collected and set as the target speed;

[0056] In this embodiment, when the opening value of the brake pedal changes from large to small, it is detected whether the opening value of the brake pedal is less than the first threshold value; if the opening value of the brake pedal is less than the first threshold value, the target speed of the vehicle is further determined. For example, in this embodiment, the first threshold value can be 5%. When the opening value of the brake pedal changes from large to small, it is determined that the user is releasing the brake pedal; if the opening value of the brake pedal is less than 5%, the target speed of the vehicle is determined by recording the current speed of the vehicle, that is, the speed at which the vehicle stabilizes after deceleration. It should be noted that the value "5%" cited in this embodiment is only used to illustrate this embodiment and is not a limiting value.

[0057] Step S20, when a first speed difference between the actual vehicle speed and the target vehicle speed is greater than a second threshold, determining a target braking torque of the retarder according to the target vehicle speed;

[0058] In the present embodiment, whether the first speed difference between the actual speed of the vehicle and the target speed is greater than the second threshold value; when the first speed difference between the actual speed of the vehicle and the target speed is greater than the second threshold value, the target braking torque of the retarder is further determined according to the target speed. For example, in the present embodiment, the first speed difference can be 10km / h, and the second threshold value can be 5km / h. In order to ensure the stability of the vehicle speed, the speed difference between the actual speed of the vehicle and the target speed is more stable at 5km / h. When the speed difference between the actual speed of the vehicle and the target speed is 10km / h greater than the second threshold value 5km / h, the vehicle can determine the target braking torque of the retarder through the target speed. It should be noted that the numerical values ​​"10km / h" and "5km / h" in the present embodiment are only used to illustrate the present embodiment and are not limiting values.

[0059] Furthermore, in one embodiment, the step of determining the target braking torque of the retarder according to the target vehicle speed includes:

[0060] Substituting the target vehicle speed into the first formula, the first formula is:

[0061]

[0062] Wherein, a', b', c', d', e', f', g', h' and i' are constants; V0 is the target speed; m is the weight of the vehicle; g is the acceleration due to gravity; is the slope angle; n e is the engine speed; i e is the gearbox ratio;

[0063] Substituting the target vehicle speed into the second formula, the second formula is:

[0064]

[0065] Where, j' is a constant; r is the tire radius; i0 is the drive axle speed ratio;

[0066] Solve the first and second formulas together to get n e 、i e Multiple solutions of ;

[0067] Substituting multiple groups of solutions into the third formula respectively, the braking torque of multiple retarders is obtained. The third formula is:

[0068]

[0069] Among them, T he is the braking torque of the retarder;

[0070] With the maximum T he is the target braking torque of the retarder.

[0071] In this embodiment, the target braking torque of the retarder is further determined according to the target vehicle speed;

[0072] For example: According to the driving force balance equation:

[0073] W 发 =(W 总 -W 风 -W 滚 ) / (1+η)…………………………………………(Formula 1)

[0074]

[0075] W 总 =F 总 V0…………………………………………(Formula 3)

[0076] Combining Formula 1, Formula 2 and Formula 3, the formula for auxiliary braking power is:

[0077]

[0078] Another formula for auxiliary braking power is:

[0079]

[0080] Among them, W 总 is the total power; V0 is the set vehicle speed; W 风 The air resistance power is 1.95kw; W 滚 =mg*Cr*V0 (m is the vehicle mass, g is the acceleration of gravity, Cr is the rolling resistance coefficient, which is taken as 0.01); W 发 : auxiliary braking power; η: loss efficiency is 0.15; Slope angle.

[0081] The formula for the braking torque of the retarder is:

[0082] T he =λρgD 5 (n e i e ) 2 …………………………………………(Formula 6)

[0083] Among them, T he is the braking torque of the retarder; λ is the braking torque coefficient; ρ is the working fluid density; D is the effective diameter of the circulation circle; n e is the engine speed; i e is the gearbox ratio.

[0084] Combining Formula 3, Formula 4 and Formula 5, we get the following formula:

[0085]

[0086] Reference Figure 2 , Figure 2 FIG. 1 is a schematic diagram of a curve showing the relationship between the braking torque and the transmission shaft speed of a test retarder in one embodiment of the present invention. Figure 2 As shown in the figure, the approximate formula obtained by fitting the retarder characteristic curve is as follows:

[0087]

[0088] Combining Formula 7 and Formula 8, we get the following formula:

[0089]

[0090] According to the tire radius and drive axle speed ratio, the following formula can be obtained:

[0091]

[0092] Among them, i0 is the drive axle speed ratio; r is the tire radius.

[0093] According to the correspondence between the vehicle speed, the engine speed and the gearbox ratio, the vehicle speed range corresponding to each gearbox ratio is further determined, so that when the target speed is a fixed value, fixed values ​​of multiple gearbox ratios can be obtained.

[0094] Solve formula 9 and formula 10 together to get n e 、i e Multiple solutions of ;

[0095] Substitute multiple groups of solutions into the approximate formula obtained by fitting the retarder characteristic curve, that is, formula 8, to obtain the braking torque of multiple retarders;

[0096] With the maximum T he is the target braking torque of the retarder.

[0097] Step S30, performing auxiliary braking according to the target braking torque of the retarder to control the vehicle speed;

[0098] In this embodiment, the vehicle is further subjected to auxiliary braking according to the target braking force of the retarder to control the vehicle speed. For example, the target braking torque of the retarder is calculated, and the braking torque is adjusted by the torque converter in the retarder to perform auxiliary braking on the vehicle, thereby controlling the vehicle speed.

[0099] In one embodiment, referring to Figure 3 , Figure 3 FIG. 1 is a flow chart of auxiliary braking by the target braking torque of the retarder in one embodiment of the present invention. Figure 3 As shown, the vehicle speed control method includes:

[0100] Furthermore, in one embodiment, step S30 includes:

[0101] Step S301, determining a target engine speed and a target gearbox speed ratio according to a target braking torque of the retarder;

[0102] In this embodiment, the target engine speed and the target gearbox speed ratio are further determined according to the target braking torque of the retarder. e 、i e Among the multiple solutions of he is the target braking torque of the retarder, which corresponds to an n e and i e The fixed value of n e The value of is determined as the target engine speed, and i e The value of is determined as the target gearbox ratio.

[0103] Step S302, determining a target transmission shaft speed according to the target engine speed and the target gearbox speed ratio;

[0104] In this embodiment, the target transmission shaft speed is further determined based on the correspondence between the transmission shaft speed, the engine speed and the transmission speed ratio; for example, the transmission shaft speed is the product of the engine speed and the transmission speed ratio, and the target transmission shaft speed is determined based on the target engine speed and the target transmission speed ratio.

[0105] Step S303, according to the target transmission shaft speed, controlling the engine to reach the target engine speed, controlling the transmission to reach the target transmission speed ratio, so as to control the vehicle speed.

[0106] In this embodiment, the target braking torque of the retarder acts on the transmission shaft to control the transmission shaft to reach the target transmission shaft speed, and the transmission shaft further controls the engine to reach the target engine speed, and controls the gearbox to reach the target gearbox speed ratio. For example, the target braking torque of the retarder gives the transmission shaft a reaction force to control the transmission shaft to reach the target transmission shaft speed, and the transmission shaft further controls the engine to reach the target engine speed, and controls the gearbox to reach the target gearbox speed ratio, so as to control the vehicle speed to reach the target vehicle speed.

[0107] Further, in one embodiment, after the step of determining the target engine speed and the target gearbox speed ratio according to the target braking torque of the retarder, the method further includes:

[0108] detecting whether the target engine speed is greater than a third threshold;

[0109] If the target engine speed is not greater than the third threshold, the step of determining the target drive shaft speed according to the target engine speed and the target gearbox speed ratio is executed; if the target engine speed is greater than the third threshold, an alarm is output.

[0110] In this embodiment, according to the determined target engine speed, it is further detected whether the target engine speed is greater than the third threshold; if the target engine speed is not greater than the third threshold, the target transmission shaft speed is further determined; if the target engine speed is greater than the third threshold, an alarm is output, wherein the third threshold is the maximum safe speed of the engine. For example, the third threshold may be 4000rad / min, and the speed of the target engine may be 5000rad / min. When the speed of the target engine is not greater than 4000rad / min, the target transmission shaft is further determined according to the target engine speed and the target gear ratio; if the speed of the target engine is 5000rad / min, which has exceeded the maximum safe speed of the engine of 4000rad / min, an alarm is output, such as the auxiliary brake switch of the vehicle instrument keeps flashing, the retarder braking function is suspended, and the slope of the road ahead is too large or the target vehicle speed is too fast. It should be noted that the values ​​"4000rad / min" and "5000rad / min" in this embodiment are only used to illustrate this embodiment and are not limiting values.

[0111] Further, in one embodiment, referring to Figure 4 , Figure 4 FIG. 2 is a flow chart of the second embodiment of the vehicle speed control method of the present invention. Figure 4 As shown, after step S30, the vehicle speed control method includes:

[0112] Step S40, determining a theoretical deceleration time according to the actual vehicle speed, the target vehicle speed, the target engine speed and the target gearbox speed ratio;

[0113] Step S50, adding a preset duration to the theoretical deceleration duration to obtain a target deceleration duration;

[0114] In this embodiment, in order to ensure that the braking torque of the retarder is effective in assisting braking, the theoretical deceleration time △t can be further determined according to the actual vehicle speed, the target vehicle speed, the target engine speed and the target gearbox ratio, wherein the theoretical deceleration time is the theoretical time for the retarder to control the vehicle speed to reach the target vehicle speed. In fact, there will be a certain error in the process of controlling the vehicle speed, and the theoretical deceleration time plus a preset time can further obtain the target deceleration time. For example, the pressure formula of the engine is:

[0115] F 发 =W 发 / V0=ma……………………(Formula 11)

[0116] Combining Formula 11 and Formula 5, we get the following formula:

[0117]

[0118] According to the actual vehicle speed, the target vehicle speed, the target engine speed and the target gearbox speed ratio, a theoretical deceleration time Δt is further obtained, and the formula is as follows:

[0119]

[0120] At this time, if the theoretical deceleration time is 5s and the preset time is 1s, the two are added to determine the target deceleration time of 6s, that is, the target braking torque of the retarder for auxiliary braking is 6s to control the vehicle speed. The values ​​"5s", "1s" and "6s" in this embodiment are only used to illustrate this embodiment and are not limiting values.

[0121] Step S60, when the control time reaches the target deceleration time, obtaining a new actual vehicle speed, and detecting whether a second speed difference between the new actual vehicle speed and the target vehicle speed is less than a fourth threshold, wherein the control time is the actual time for performing auxiliary braking;

[0122] Step S70: If the second speed difference is not less than a fourth threshold value, the step of performing auxiliary braking according to the target braking torque of the retarder is suspended, and an alarm is output.

[0123] In this embodiment, when the vehicle control duration reaches the target deceleration duration, it is detected whether the second speed difference between the new actual speed of the vehicle and the target speed is less than the fourth threshold value. If the second speed difference is not less than the fourth threshold value, the vehicle suspends the execution of the braking torque of the retarder for auxiliary braking and issues an alarm message. Wherein, the control duration is the duration of the vehicle for auxiliary braking, and the fourth threshold value refers to the range value that is not much different from the target speed. For example, the target speed can be 30km / h, the new actual speed can be 31km / h, and the fourth threshold value can be 0.5km / h. When the control duration of the vehicle reaches 6s, the speed difference between the new actual speed 31km / h and the target speed 30km / h is not less than 0.5km / h, and it is further determined that the vehicle auxiliary braking function fails, and the vehicle suspends the execution of the target braking torque of the retarder for auxiliary braking, and outputs an alarm reminder, such as the auxiliary brake switch of the vehicle instrument keeps flashing, the retarder braking function is suspended, the instrument pop-up window or voice reminder retarder function is limited, the brake pedal is stepped on and other signals. It should be noted that the values ​​"30 km / h", "31 km / h" and "0.5 km / h" in this embodiment are only used to illustrate this embodiment and are not limiting values.

[0124] Furthermore, in one embodiment, after step S30, the method further includes:

[0125] The temperature of the retarder is collected; whether the temperature of the retarder is greater than a fifth threshold is detected; if the temperature of the retarder is greater than the fifth threshold, the step of performing auxiliary braking according to the target braking torque of the retarder is suspended, and an alarm reminder is output.

[0126] In this embodiment, the temperature of the retarder is collected (it can be the temperature of the retarder itself, or the temperature of the liquid or gas around the retarder), and the temperature of the retarder is detected to be greater than the fifth threshold. If the temperature of the retarder is greater than the fifth threshold, it is further determined to suspend the target braking torque of the retarder for auxiliary braking, and output an alarm prompt, wherein the fifth threshold refers to the maximum safe temperature of the retarder. For example, the fifth threshold can be 95°C, and the temperature of the retarder is detected to be greater than 95°C. If the temperature of the retarder is now 100°C and greater than 95°C, it is determined to suspend the target braking torque of the retarder for auxiliary braking, and output an alarm reminder, such as the auxiliary brake switch of the vehicle instrument keeps flashing, the retarder braking function is suspended, and the instrument pop-up window or voice reminds the retarder water temperature is too high, the retarder function is limited, and the brake pedal is stepped on. It should be noted that the values ​​"100°C" and "95°C" in this embodiment are only used to illustrate this embodiment and are not limiting values.

[0127] Furthermore, in one embodiment, after step S30, the method further includes:

[0128] When an auxiliary braking function closing instruction is received, the step of performing auxiliary braking according to the target braking torque of the retarder is suspended.

[0129] In this embodiment, when the vehicle receives an instruction to turn off the auxiliary braking function, it is further determined to suspend the operation of performing auxiliary braking using the target braking torque of the retarder. For example, if the user manually turns off the auxiliary braking switch, the vehicle will no longer perform auxiliary braking using the braking torque of the retarder after receiving the instruction to turn off the auxiliary braking function.

[0130] In a second aspect, an embodiment of the present invention further provides a vehicle speed control device.

[0131] In one embodiment, referring to Figure 5 , Figure 5 FIG. 1 is a schematic diagram of the functional modules of the vehicle speed control device involved in the embodiment of the present invention. Figure 5 As shown, the vehicle speed control device includes:

[0132] A first determination module 10 is used to collect the vehicle speed and set it as the target speed if the opening value of the vehicle brake pedal changes from large to small and when the opening value is less than a first threshold;

[0133] A second determination module 20, configured to determine a target braking torque of the retarder according to the target vehicle speed when a first speed difference between the actual vehicle speed and the target vehicle speed is greater than a second threshold;

[0134] The control module 30 is used to perform auxiliary braking according to the target braking torque of the retarder to control the vehicle speed.

[0135] Further, in one embodiment, the second determining module 20 is specifically configured to:

[0136] Substituting the target vehicle speed into the first formula, the first formula is:

[0137]

[0138] Wherein, a', b', c', d', e', f', g', h' and i' are constants; V0 is the target speed; m is the weight of the vehicle; g is the acceleration due to gravity; is the slope angle; n e is the engine speed; i e is the gearbox ratio;

[0139] Substituting the target vehicle speed into the second formula, the second formula is:

[0140]

[0141] Where, j' is a constant; r is the tire radius; i0 is the drive axle speed ratio;

[0142] Solve the first and second formulas together to get n e 、i e Multiple solutions of ;

[0143] Substituting multiple groups of solutions into the third formula respectively, the braking torque of multiple retarders is obtained. The third formula is:

[0144]

[0145] Among them, T he is the braking torque of the retarder;

[0146] With the maximum T he is the target braking torque of the retarder.

[0147] Furthermore, in one embodiment, the control module 30 is specifically configured to:

[0148] Determining a target engine speed and a target gearbox speed ratio according to a target braking torque of the retarder;

[0149] Determining a target transmission shaft speed according to the target engine speed and the target gearbox speed ratio;

[0150] According to the target transmission shaft speed, the engine is controlled to reach the target engine speed, and the transmission is controlled to reach the target transmission speed ratio, so as to control the vehicle speed.

[0151] Furthermore, in one embodiment, the vehicle speed control device further includes: a first detection module, configured to:

[0152] detecting whether the target engine speed is greater than a third threshold;

[0153] If the target engine speed is not greater than the third threshold, the step of determining the target transmission shaft speed according to the target engine speed and the target gearbox speed ratio is performed;

[0154] If the target engine speed is greater than the third threshold, an alarm is output

[0155] Furthermore, in one embodiment, the second determining module 20 is further configured to:

[0156] Determining a theoretical deceleration time according to the actual vehicle speed, the target vehicle speed, the target engine speed and the target gearbox speed ratio;

[0157] Adding a preset time to the theoretical deceleration time to obtain a target deceleration time;

[0158] When the control time reaches the target deceleration time, obtaining a new actual vehicle speed, and detecting whether a second speed difference between the new actual vehicle speed and the target vehicle speed is less than a fourth threshold, wherein the control time is the time for performing auxiliary braking;

[0159] If the second speed difference is not less than a fourth threshold value, the step of performing auxiliary braking according to the target braking torque of the retarder is suspended, and an alarm is output.

[0160] Furthermore, in one embodiment, the vehicle speed control device further includes: a second detection module, configured to:

[0161] Collect the temperature of the retarder;

[0162] detecting whether the temperature of the retarder is greater than a fifth threshold;

[0163] If the temperature of the retarder is greater than a fifth threshold, the step of performing auxiliary braking according to the target braking torque of the retarder is suspended, and an alarm is output.

[0164] Furthermore, in one embodiment, the control module 30 is also used for:

[0165] When an auxiliary braking function closing instruction is received, the step of performing auxiliary braking according to the target braking torque of the retarder is suspended.

[0166] Among them, the functional implementation of each module in the above-mentioned vehicle speed control device corresponds to the various steps in the above-mentioned vehicle speed control method embodiment, and its functions and implementation processes will not be repeated here one by one.

[0167] In a third aspect, an embodiment of the present invention provides a vehicle speed control device, which may be a device having a data processing function, such as a personal computer (PC), a notebook computer, or a server.

[0168] Reference Figure 6 , Figure 6 Schematic diagram of the hardware structure of the vehicle speed control device involved in the embodiment of the present invention. In the embodiment of the present invention, the vehicle speed control device may include a processor 1001 (e.g., a central processing unit, CPU), a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. Among them, the communication bus 1002 is used to realize the connection and communication between these components; the user interface 1003 may include a display screen (Display), an input unit such as a keyboard (Keyboard); the network interface 1004 may optionally include a standard wired interface, a wireless interface (such as a wireless fidelity WIreless-FIdelity, WI-FI interface); the memory 1005 may be a high-speed random access memory (random access memory, RAM), or a stable memory (non-volatile memory), such as a disk storage, and the memory 1005 may optionally be a storage device independent of the aforementioned processor 1001. Those skilled in the art will understand that Figure 6 The hardware structure shown in the figure does not constitute a limitation of the present invention, and may include more or less components than those shown in the figure, or combine certain components, or arrange the components differently.

[0169] Continue to refer to Figure 6 , Figure 6 The memory 1005 as a computer storage medium may include an operating system, a network communication module, a user interface module, and a vehicle speed control program. The processor 1001 may call the vehicle speed control program stored in the memory 1005 and execute the vehicle speed control method provided in the embodiment of the present invention.

[0170] In a fourth aspect, an embodiment of the present invention further provides a readable storage medium.

[0171] The vehicle speed control program is stored on the readable storage medium of the present invention, wherein when the vehicle speed control program is executed by the processor, the steps of the vehicle speed control method as described above are implemented.

[0172] Among them, the method implemented when the vehicle speed control program is executed can refer to the various embodiments of the vehicle speed control method of the present invention, and will not be repeated here.

[0173] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0174] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0175] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, which is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes a number of instructions for a terminal device to execute the methods described in each embodiment of the present invention.

[0176] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A vehicle speed control method, characterized in that: The vehicle speed control method comprises: If the opening value of the vehicle brake pedal changes from large to small, and when the opening value is less than a first threshold, the vehicle speed is collected and set as the target speed; When a first speed difference between the actual vehicle speed and the target vehicle speed is greater than a second threshold, determining a target braking torque of the retarder according to the target vehicle speed; Performing auxiliary braking according to the target braking torque of the retarder to control the vehicle speed; The step of performing auxiliary braking according to the target braking torque of the retarder to control the vehicle speed includes: Determining a target engine speed and a target gearbox speed ratio according to a target braking torque of the retarder; Determining a target transmission shaft speed according to the target engine speed and the target gearbox speed ratio; According to the target transmission shaft speed, the engine is controlled to reach the target engine speed, and the transmission is controlled to reach the target transmission speed ratio, so as to control the vehicle speed.

2. The vehicle speed control method according to claim 1, characterized in that: The step of determining the target braking torque of the retarder according to the target vehicle speed comprises: Substituting the target vehicle speed into the first formula, the first formula is: Wherein, a', b', c', d', e', f', g', h' and i' are constants; V0 is the target speed; m is the weight of the vehicle; g is the acceleration due to gravity; is the slope angle; n e is the engine speed; i e is the gearbox ratio; Substituting the target vehicle speed into the second formula, the second formula is: Among them, j' is a constant; r is the tire radius; i0 is the drive axle speed ratio; Solve the first and second formulas together to get n e 、i e Multiple solutions of ; Substituting multiple groups of solutions into the third formula respectively, the braking torque of multiple retarders is obtained. The third formula is: Among them, T he is the braking torque of the retarder; With the maximum T he is the target braking torque of the retarder.

3. The vehicle speed control method according to claim 1, characterized in that: After the step of determining the target engine speed and the target gearbox speed ratio according to the target braking torque of the retarder, the method further includes: detecting whether the target engine speed is greater than a third threshold; If the target engine speed is not greater than the third threshold, the step of determining the target transmission shaft speed according to the target engine speed and the target gearbox speed ratio is performed; If the target engine speed is greater than a third threshold, an alarm is output.

4. The vehicle speed control method according to claim 1, characterized in that: After the step of performing auxiliary braking according to the target braking torque of the retarder to control the vehicle speed, the method further includes: Determining a theoretical deceleration time according to the actual vehicle speed, the target vehicle speed, the target engine speed and the target gearbox speed ratio; Adding a preset time to the theoretical deceleration time to obtain a target deceleration time; When the control time reaches the target deceleration time, obtaining a new actual vehicle speed, and detecting whether a second speed difference between the new actual vehicle speed and the target vehicle speed is less than a fourth threshold, wherein the control time is the time for performing auxiliary braking; If the second speed difference is not less than a fourth threshold value, the step of performing auxiliary braking according to the target braking torque of the retarder is suspended, and an alarm is output.

5. The vehicle speed control method according to any one of claims 1 to 4, characterized in that: After the step of performing auxiliary braking according to the target braking torque of the retarder to control the vehicle speed, the method further includes: Collect the temperature of the retarder; detecting whether the temperature of the retarder is greater than a fifth threshold; If the temperature of the retarder is greater than a fifth threshold, the step of performing auxiliary braking according to the target braking torque of the retarder is suspended, and an alarm is output.

6. The vehicle speed control method according to any one of claims 1 to 4, characterized in that: After the step of performing auxiliary braking according to the target braking torque of the retarder to control the vehicle speed, the method further includes: When an auxiliary braking function closing instruction is received, the step of performing auxiliary braking according to the target braking torque of the retarder is suspended.

7. A vehicle speed control device, characterized in that: The vehicle speed control device comprises: A first determination module is used to collect the vehicle speed and set it as the target speed if the opening value of the vehicle brake pedal changes from large to small and when the opening value is less than a first threshold; A second determination module, configured to determine a target braking torque of the retarder according to the target vehicle speed when a first speed difference between the actual vehicle speed and the target vehicle speed is greater than a second threshold; A control module is used to perform auxiliary braking according to the target braking torque of the retarder to control the vehicle speed; including: determining a target engine speed and a target gearbox speed ratio according to the target braking torque of the retarder; determining a target drive shaft speed according to the target engine speed and the target gearbox speed ratio; and controlling the engine to reach the target engine speed and the gearbox to reach the target gearbox speed ratio according to the target drive shaft speed to control the vehicle speed.

8. A vehicle speed control device, characterized in that: The vehicle speed control device includes a processor, a memory, and a vehicle speed control program stored in the memory and executable by the processor, wherein when the vehicle speed control program is executed by the processor, the steps of the vehicle speed control method as described in any one of claims 1 to 6 are implemented.

9. A readable storage medium, characterized in that: The readable storage medium stores a vehicle speed control program, wherein when the vehicle speed control program is executed by a processor, the steps of the vehicle speed control method according to any one of claims 1 to 6 are implemented.

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