An AMT gear shifting method in an auxiliary braking condition, a storage medium and a device

Abstract

The application discloses an AMT gear shifting method in an auxiliary braking condition, a storage medium and a device, relates to the fields of brake temperature estimation and auxiliary braking use evaluation, and the method comprises the following steps: when an AMT controller monitors that there is torque of a hydraulic retarder or engine braking, the AMT controller enters an auxiliary braking mode, and it is judged that: if a vehicle auxiliary braking gear has a constant speed function, then the auxiliary braking torque is automatically adjusted according to the change of the vehicle speed to keep the vehicle speed stable; if the auxiliary braking gear is used for auxiliary braking, then an AMT gear shifting interval is determined, and the AMT gear shifting interval is corrected according to braking power; and if an auxiliary braking handle is not opened, then the engine speed is controlled to be in an engine braking normal working speed range, and the engine speed is adjusted in real time according to the hydraulic retarder. According to the application, by selecting a suitable gearbox gear, the braking effect can be ensured, and the use experience of a driver can be prevented from being affected by the excessively high speed and excessively large noise.

Description

Technical Field

[0001] This invention relates to the fields of brake temperature prediction and auxiliary braking usage evaluation, specifically to an AMT shifting method, storage medium, and device for auxiliary braking conditions. Background Technology

[0002] Auxiliary braking includes hydraulic retarders and engine braking. Engine braking effectiveness is generally proportional to engine speed. Hydraulic retarders convert the vehicle's kinetic energy into heat, which is then dissipated through the engine cooling system. If the braking power is high and the engine speed is low, the vehicle's heat dissipation capacity will be poor. When the retarder coolant temperature reaches a certain level, it will limit torque to prevent the vehicle's coolant temperature from overheating and affecting the retarder's braking effect. Higher engine speeds result in better retarder performance. However, higher engine speeds also lead to greater engine noise, which negatively impacts the driver's experience. Therefore, an appropriate engine speed is needed to meet the vehicle's operational requirements.

[0003] Engine braking is typically standard equipment, while a hydraulic retarder is an optional extra depending on user needs. Previously, vehicles generally featured mechanical transmissions, requiring users to adjust transmission speeds according to road conditions to meet vehicle requirements. As user demands increased, the adoption rate of AMT (Automated Mechanical Transmission) gradually rose. AMT typically adjusts engine speed based on retarder torque and engine braking torque. With regulatory requirements, some models are now required to have an EBS (Electronic Brake Control) system. The EBS system has EBI (Electronic Stability Control) functionality; when the brake pedal travel is short, the EBS system requests engine braking and a hydraulic retarder, thereby reducing brake pad wear.

[0004] In practical applications, a small number of manual transmission users do not understand the requirements for using auxiliary braking and do not actively increase the engine speed according to road conditions, thus affecting the effectiveness of auxiliary braking. Meanwhile, existing AMT strategies require adjusting the transmission gears based on the retarder and actual engine torque, failing to distinguish between assisted braking activated by the throttle and EBS. When EBS is activated, both engine braking torque and hydraulic retarder braking torque are relatively high, leading to more downshifts in the AMT and higher engine speeds. Since braking is frequent in real-world driving, each braking action results in significant downshifts, causing considerable noise. Users complain about excessive engine downshifting and noise during braking, leading some to disable the EBI function, thus preventing its use to reduce friction pad wear.

[0005] Engine braking operates under the following conditions: engine speed above 1000 rpm, clutch not engaged, and transmission not in neutral. Higher engine speed results in greater braking power, but also higher engine speed leads to greater engine noise.

[0006] The hydraulic retarder operates at speeds above 10 km / h. However, as speed increases, braking torque gradually increases. At 40 km / h (with a rear axle ratio of 3.42), the retarder torque reaches its maximum. Further speed increases do not change the braking torque, but braking power increases with speed. When the retarder power reaches 450 kW, further speed increases do not change the braking power, but the braking torque response decreases. After use, the retarder's coolant and oil temperatures gradually rise, requiring the engine cooling system to dissipate the heat. If the engine cooling system cannot dissipate the heat in time, the coolant and oil temperatures will reach the retarder's torque-limiting temperature. In this case, the retarder will limit torque, reducing retarder torque and braking power to prevent excessively high coolant and oil temperatures. Excessively high coolant temperatures may damage the engine, and excessively high oil temperatures will reduce the retarder oil replacement interval. If it is necessary to increase the braking power of the retarder, the gearbox can be downshifted, the engine speed increased, the engine water pump and engine fan speed increased, the engine coolant flow rate and the air velocity in the coolant tank increased, thereby increasing the heat dissipation power of the engine cooling system.

[0007] Therefore, how to select the appropriate gearbox gear according to road conditions, that is, to increase the engine speed to ensure the braking effect of engine braking and hydraulic retarder, while controlling the engine speed when the auxiliary braking is small, so as to prevent the engine speed from being too high and causing excessive noise that would affect the driver's experience, is a problem that urgently needs to be solved. Summary of the Invention

[0008] In view of the deficiencies in the existing technology, the purpose of this invention is to provide an AMT shifting method, storage medium and device for auxiliary braking conditions. By selecting the appropriate gearbox gear, the braking effect can be guaranteed, and excessive noise due to high speed can be prevented from affecting the driver's experience.

[0009] To achieve the above objectives, the present invention provides an AMT shifting method under auxiliary braking conditions, specifically including the following steps:

[0010] When the AMT controller detects torque in the hydraulic retarder or engine braking, the AMT controller enters auxiliary braking mode and determines:

[0011] If the vehicle's auxiliary braking gear has a constant speed function, it will automatically adjust the auxiliary braking torque according to changes in vehicle speed to maintain a stable vehicle speed.

[0012] If the auxiliary braking gear is used for auxiliary braking, the AMT shift range is determined and the AMT shift range is adjusted according to the braking power to control the hydraulic retarder at the set temperature.

[0013] If the auxiliary brake lever is not engaged, the engine speed is controlled within the normal operating speed range for engine braking, and the engine speed is adjusted in real time according to the hydraulic retarder.

[0014] Based on the above technical solution, the step of automatically adjusting the auxiliary braking torque according to changes in vehicle speed to maintain stable vehicle speed includes the following specific steps:

[0015] The vehicle is switched to constant speed gear, and when the hydraulic retarder torque is less than 0, a gear shift operation is performed, shifting to the highest gear where the engine speed exceeds the set minimum speed, and then a check is performed to determine whether the hydraulic retarder torque is equal to 0:

[0016] If not, shift to the highest gear where the engine speed exceeds the set maximum speed, then gradually reduce the engine speed until the hydraulic retarder torque is equal to 0, and then exit the auxiliary braking mode.

[0017] If so, then exit the auxiliary braking mode.

[0018] Based on the above technical solution, the specific steps of shifting to the highest gear where the engine speed exceeds the set maximum speed, then gradually reducing the engine speed until the hydraulic retarder torque equals 0, and then exiting the auxiliary braking mode include:

[0019] Determine if the vehicle speed exceeds the speed limit:

[0020] If so, shift to the highest gear where the engine speed exceeds the set maximum speed, then shift to the highest gear where the engine speed exceeds the set minimum speed, and then check again whether the hydraulic retarder torque is equal to 0, and repeat this cycle.

[0021] If not, then determine whether the braking power of the hydraulic retarder exceeds the power limit:

[0022] If the power is greater than the limit, shift to the highest gear where the engine speed exceeds the second set speed, then shift to the highest gear where the engine speed exceeds the set minimum speed, and then check again whether the torque of the hydraulic retarder is equal to 0, and repeat this cycle.

[0023] If the power limit is not exceeded, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds the first set speed, then shift to the highest gear where the engine speed exceeds the set minimum speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the power limit is not exceeded, shift to the highest gear where the engine speed exceeds the set minimum speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle.

[0024] Among them, the maximum speed is set to be greater than the second speed, the second speed is set to be greater than the first speed, and the first speed is set to be greater than the minimum speed.

[0025] Based on the above technical solution, the braking power of the hydraulic retarder is calculated as follows:

[0026]

[0027] Where P represents the braking power of the hydraulic retarder, T represents the torque of the hydraulic retarder, the torque of the hydraulic retarder is equal to the product of the maximum torque of the hydraulic retarder and the percentage of the torque required by the hydraulic retarder, and n represents the speed of the drive shaft.

[0028] Based on the above technical solutions,

[0029] Based on the braking power of the hydraulic retarder, the auxiliary braking of the hydraulic retarder is divided into three levels: level 1, level 2, and level 3.

[0030] The corresponding engine speed is set according to the auxiliary braking gear of the hydraulic retarder;

[0031] The first setting of the hydraulic retarder corresponds to the third and fourth set speeds, and the fourth set speed is greater than the third set speed.

[0032] The hydraulic retarder's second setting corresponds to the fifth and sixth set speeds, with the sixth set speed being greater than the fifth set speed.

[0033] The three speed settings of the hydraulic retarder correspond to the seventh, eighth, and ninth set speeds, with the ninth set speed being greater than the eighth set speed, and the eighth set speed being greater than the seventh set speed.

[0034] Based on the above technical solution, when the hydraulic retarder is in gear 1, the specific steps of adjusting the AMT shift range according to the braking power to control the hydraulic retarder at the set temperature include:

[0035] When the torque of the hydraulic retarder is determined to be less than 0, shift to the highest gear where the engine speed exceeds the third set speed.

[0036] Determine if the torque of the hydraulic retarder is equal to 0:

[0037] If not, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds the fourth set speed, then shift to the highest gear where the engine speed exceeds the third set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the temperature does not exceed the temperature limit, shift to the highest gear where the engine speed exceeds the third set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle.

[0038] If so, then exit the auxiliary braking mode.

[0039] Based on the above technical solution, when the hydraulic retarder is in gear 2, the specific steps of adjusting the AMT shift range according to the braking power to control the hydraulic retarder at the set temperature include:

[0040] When the torque of the hydraulic retarder is determined to be less than 0, shift to the highest gear where the engine speed exceeds the fifth set speed.

[0041] Determine if the torque of the hydraulic retarder is equal to 0:

[0042] If not, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds the sixth set speed, then shift to the highest gear where the engine speed exceeds the fifth set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the temperature does not exceed the temperature limit, shift to the highest gear where the engine speed exceeds the fifth set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle.

[0043] If so, then exit the auxiliary braking mode.

[0044] Based on the above technical solution, when the hydraulic retarder is in gear 3, the step of adjusting the AMT shift range according to the braking power to control the hydraulic retarder at the set temperature includes the following specific steps:

[0045] When the torque of the hydraulic retarder is determined to be less than 0, shift to the highest gear where the engine speed exceeds the seventh set speed.

[0046] Determine if the torque of the hydraulic retarder is equal to 0:

[0047] If not, then determine whether the braking power of the hydraulic retarder exceeds the power limit:

[0048] If the power is greater than the limit, shift to the highest gear where the engine speed exceeds the ninth set speed, then shift to the highest gear where the engine speed exceeds the seventh set speed, and then check whether the torque of the hydraulic retarder is equal to 0 again, and repeat this cycle.

[0049] If the power limit is not exceeded, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds the eighth set speed, then shift to the highest gear where the engine speed exceeds the seventh set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the temperature limit is not exceeded, shift to the highest gear where the engine speed exceeds the seventh set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle.

[0050] Based on the above technical solution, the step of controlling the engine speed to be within the normal operating speed range for engine braking, and adjusting the engine speed in real time according to the hydraulic retarder, includes the following specific steps:

[0051] When the torque of the hydraulic retarder is determined to be less than 0, shift to the highest gear where the engine speed exceeds 1000 rpm;

[0052] Determine if the torque of the hydraulic retarder is equal to 0:

[0053] If not, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds 1250 rpm, then shift to the highest gear where the engine speed exceeds 1000 rpm, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the temperature does not exceed the temperature limit, shift to the highest gear where the engine speed exceeds 1000 rpm, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle.

[0054] If so, then exit the auxiliary braking mode.

[0055] This invention provides an AMT shifting device for auxiliary braking conditions, comprising:

[0056] The judgment module is used to enter the auxiliary braking mode when the AMT controller detects that there is torque in the hydraulic retarder or engine braking. If the vehicle's auxiliary braking gear has a constant speed function, the first execution module is driven to work. If the auxiliary braking gear is used for auxiliary braking, the second execution module is driven to work. If the auxiliary braking lever is not opened, the third execution module is driven to work.

[0057] The first execution module is used to automatically adjust the auxiliary braking torque according to changes in vehicle speed to maintain stable vehicle speed;

[0058] The second execution module is used to determine the AMT shift range and correct the AMT shift range according to the braking power in order to control the hydraulic retarder to be at the set temperature.

[0059] The third execution module is used to control the engine speed within the normal operating speed range of engine braking, and to adjust the engine speed in real time according to the hydraulic retarder.

[0060] Compared with the prior art, the advantages of the present invention are as follows: When the AMT controller detects torque in the hydraulic retarder or engine braking, the AMT controller enters the auxiliary braking mode. If the vehicle's auxiliary braking gear has a constant speed function, the auxiliary braking torque is automatically adjusted according to the vehicle speed to maintain a stable vehicle speed. If the auxiliary braking gear is used for auxiliary braking, the AMT shift range is determined and corrected according to the braking power to control the hydraulic retarder at the set temperature. If the auxiliary braking lever is not open, the engine speed is controlled within the normal operating speed range for engine braking, and the engine speed is adjusted in real time according to the hydraulic retarder. That is, by selecting the appropriate gearbox gear, the engine speed can be increased to ensure the braking effect of engine braking and hydraulic retarder. At the same time, when the auxiliary braking is small, the engine speed is controlled to prevent excessive speed and noise from affecting the driver's experience. Attached Figure Description

[0061] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0062] Figure 1 A schematic diagram of the control principle for auxiliary braking;

[0063] Figure 2 This is a flowchart of an AMT shifting method under auxiliary braking conditions according to an embodiment of the present invention;

[0064] Figure 3 Control flowchart for vehicle auxiliary braking gear with constant speed function;

[0065] Figure 4 This is the control flowchart when the hydraulic retarder is in position 1.

[0066] Figure 5 The control flowchart is shown when the hydraulic retarder is in gear 2.

[0067] Figure 6 The control flowchart is shown when the hydraulic retarder is in position 3.

[0068] Figure 7 Control flowchart for when the auxiliary brake lever is not open;

[0069] Figure 8 A schematic diagram illustrating the auxiliary braking connection principle of a vehicle equipped with AMT;

[0070] Figure 9 This is a schematic diagram of the auxiliary braking connection principle for a vehicle without AMT (Automated Manual Transmission). Detailed Implementation

[0071] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0072] See Figure 1 As shown, regarding auxiliary braking, it's important to first understand that the auxiliary brake lever is connected to the VECU (Vehicle Controller Unit). The VECU sends braking torque requests and a signal indicating whether to maintain a constant speed. When the VECU sends a constant speed request, the retarder controller uses the current vehicle speed as the target speed. As the vehicle speed increases, the hydraulic retarder's braking torque increases; as the vehicle speed decreases, the hydraulic retarder's torque decreases, ensuring the speed difference remains within 3 km / h. When the hydraulic retarder's braking force cannot control the vehicle speed, the retarder controller sends an engine braking torque request to the engine controller, and engine braking will also engage. When the VECU does not have a constant speed request, it sends both engine braking torque and hydraulic retarder braking torque requests, and the hydraulic retarder and engine respond according to the actual conditions.

[0073] Additionally, to reduce wear on the brake pads, when the EBS system's foot valve is depressed, the EBS controller sends braking torque requests to the retarder controller and engine controller. The hydraulic retarder and engine respond to these requests. When both the VECU and EBS request braking torque, the hydraulic retarder and engine brakes will respond to the request with the greater requested torque. If the clutch is depressed and the transmission is in neutral, engine braking will not respond. Engine braking will also not respond when the engine speed is below 1000 rpm. These signals will not affect the hydraulic retarder. If the vehicle speed is too low, the hydraulic retarder will not respond, but engine braking will.

[0074] See Figure 2 As shown in the figure, an AMT shifting method under auxiliary braking conditions provided by an embodiment of the present invention specifically includes the following steps:

[0075] S1: When the AMT controller detects torque in the hydraulic retarder or engine brake, the AMT controller enters the auxiliary braking mode and determines whether the vehicle's auxiliary braking gear has a constant speed function. If the auxiliary braking gear is used for auxiliary braking, the controller will proceed to S2. If the auxiliary braking gear is used for auxiliary braking, the controller will proceed to S3. If the auxiliary braking lever is not open, the controller will proceed to S4.

[0076] S2: Automatically adjusts the auxiliary braking torque according to changes in vehicle speed to maintain stable vehicle speed;

[0077] S3: Determine the AMT shift range and adjust the AMT shift range according to the braking power to control the hydraulic retarder at the set temperature;

[0078] S4: Controls the engine speed within the normal operating speed range for engine braking, and adjusts the engine speed in real time according to the hydraulic retarder.

[0079] In this invention, the auxiliary braking torque is automatically adjusted according to changes in vehicle speed to maintain stable vehicle speed. Specific steps include:

[0080] The vehicle is switched to constant speed gear, and when the hydraulic retarder torque is less than 0, a gear shift operation is performed, shifting to the highest gear where the engine speed exceeds the set minimum speed, and then a check is performed to determine whether the hydraulic retarder torque is equal to 0:

[0081] If not, shift to the highest gear where the engine speed exceeds the set maximum speed, then gradually reduce the engine speed until the hydraulic retarder torque is equal to 0, and then exit the auxiliary braking mode.

[0082] If so, then exit the auxiliary braking mode.

[0083] In this invention, the engine speed is shifted to the highest gear where the engine speed exceeds the set maximum speed, and then the engine speed is gradually reduced until the torque of the hydraulic retarder is equal to 0, and then the auxiliary braking mode is exited. The specific steps include:

[0084] Determine if the vehicle speed exceeds the speed limit:

[0085] If so, shift to the highest gear where the engine speed exceeds the set maximum speed, then shift to the highest gear where the engine speed exceeds the set minimum speed, and then check again whether the hydraulic retarder torque is equal to 0, and repeat this cycle.

[0086] If not, then determine whether the braking power of the hydraulic retarder exceeds the power limit:

[0087] If the power is greater than the limit, shift to the highest gear where the engine speed exceeds the second set speed, then shift to the highest gear where the engine speed exceeds the set minimum speed, and then check again whether the torque of the hydraulic retarder is equal to 0, and repeat this cycle.

[0088] If the power limit is not exceeded, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds the first set speed, then shift to the highest gear where the engine speed exceeds the set minimum speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the power limit is not exceeded, shift to the highest gear where the engine speed exceeds the set minimum speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle.

[0089] Among them, the maximum speed is set to be greater than the second speed, the second speed is set to be greater than the first speed, and the first speed is set to be greater than the minimum speed.

[0090] When the vehicle's auxiliary braking mode has a constant speed function, the auxiliary braking torque automatically adjusts according to vehicle speed changes to maintain a stable speed. First, it shifts to the highest gear where the engine speed exceeds the set minimum speed, ensuring the hydraulic retarder can operate and meeting the engine speed requirements for typical inclines. When the hydraulic retarder's braking power is high, the transmission downshifts to the highest gear exceeding the second set speed. If the auxiliary braking cannot stabilize the speed and the speed exceeds the limit, the transmission downshifts to the highest gear exceeding the set maximum speed. If the braking power is low, but the hydraulic retarder has been used for a long time, the retarder coolant temperature will gradually rise. When the coolant temperature reaches the limit, the transmission downshifts to the highest gear exceeding the first set speed. To ensure the auxiliary braking effect, the engine speed must be increased. This is generally only done when the ambient temperature is very high or the incline is steep and the vehicle speed is very high; such situations are rare and acceptable to users. When the hydraulic retarder has a large braking power, the retarder water temperature rises rapidly. It is necessary to increase the engine speed in advance to prevent the water temperature from becoming too high and the vehicle speed from becoming unstable. In order to prevent the engine speed from rising too high at once, the engine speed can be increased to above the first set speed first to reduce the number of times the speed exceeds the set maximum speed.

[0091] The following combination Figure 3 The process involves shifting to the highest gear where the engine speed exceeds the set maximum speed, then gradually reducing the engine speed until the hydraulic retarder torque equals 0, and then exiting the auxiliary braking mode. Specific instructions will follow.

[0092] S201: Switch the auxiliary braking gear to constant speed gear, then turn to S202;

[0093] S202: Determine if the torque of the hydraulic retarder is less than 0. If not, go to S202; if yes, go to S203.

[0094] S203: Shift to the highest gear where the engine speed exceeds the set minimum speed, then switch to S204;

[0095] S204: Determine if the torque of the hydraulic retarder is equal to 0. If yes, proceed to S205; otherwise, proceed to S206.

[0096] S205, Exit auxiliary braking mode, end;

[0097] S206: Determine if the vehicle speed exceeds the speed limit. If yes, proceed to S207; otherwise, proceed to S208.

[0098] S207: Shift to the highest gear where the engine speed exceeds the set maximum speed, then switch to S203;

[0099] S208: Determine whether the braking power of the hydraulic retarder is greater than the power limit. If yes, proceed to S209; otherwise, proceed to S210.

[0100] S209: Shift to the highest gear where the engine speed exceeds the second set speed, then switch to S203;

[0101] S210: Determine if the water temperature of the hydraulic retarder is greater than the temperature limit. If yes, proceed to S211; otherwise, proceed to S203.

[0102] S211: Shift to the highest gear where the engine speed exceeds the first set speed, then switch to S203.

[0103] In this invention, the braking power of the hydraulic retarder is calculated as follows:

[0104]

[0105] Where P represents the braking power of the hydraulic retarder, T represents the torque of the hydraulic retarder, the torque of the hydraulic retarder is equal to the product of the maximum torque of the hydraulic retarder and the percentage of the torque required by the hydraulic retarder, and n represents the speed of the drive shaft.

[0106] In this invention, based on the braking power of the hydraulic retarder, the auxiliary braking of the hydraulic retarder is divided into three levels: level 1, level 2, and level 3, with the corresponding braking power increasing sequentially.

[0107] The engine speed is set according to the auxiliary braking gear of the hydraulic retarder; gear 1 of the hydraulic retarder corresponds to the third and fourth set speeds, and the fourth set speed is greater than the third set speed; gear 2 of the hydraulic retarder corresponds to the fifth and sixth set speeds, and the sixth set speed is greater than the fifth set speed; gear 3 of the hydraulic retarder corresponds to the seventh, eighth and ninth set speeds, and the ninth set speed is greater than the eighth set speed, and the eighth set speed is greater than the seventh set speed.

[0108] When the vehicle's auxiliary braking gear is used for assisted braking, the braking torque is fixed. In order to ensure that different gears have different assisted braking effects, the AMT shift range is first determined according to the auxiliary braking gear. However, different vehicle speeds result in different braking power and different amounts of heat generated. The shift range is adjusted according to the braking power. As the auxiliary braking works, the hydraulic retarder temperature gradually rises. If the braking power is high and the water temperature is high, the AMT shift range is adjusted to ensure the retarder's effectiveness.

[0109] When the hydraulic retarder is in gear 1 or 2, the braking power is not very high, the user's demand for vehicle deceleration is relatively small, and the engine speed does not need to be too high. When the hydraulic retarder is in gear 3, the braking power will be very high at normal vehicle speed. If the engine speed is low, the hydraulic retarder water temperature will rise quickly to the torque limiting temperature, requiring a higher engine speed. If the vehicle speed is low, the braking power is not very high, and the engine speed can be appropriately reduced.

[0110] In this invention, when the hydraulic retarder is in gear 1, the step of adjusting the AMT shift range according to the braking power to control the hydraulic retarder at a set temperature includes the following steps:

[0111] When the torque of the hydraulic retarder is determined to be less than 0, shift to the highest gear where the engine speed exceeds the third set speed.

[0112] Determine if the torque of the hydraulic retarder is equal to 0:

[0113] If not, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds the fourth set speed, then shift to the highest gear where the engine speed exceeds the third set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the temperature does not exceed the temperature limit, shift to the highest gear where the engine speed exceeds the third set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle.

[0114] If so, then exit the auxiliary braking mode.

[0115] The following combination Figure 4 The following is a detailed explanation of how, when the hydraulic retarder is in gear 1, the AMT shift range is adjusted according to the braking power to control the hydraulic retarder to be at the set temperature.

[0116] S301: Switch the hydraulic retarder to gear 1, then switch to S302;

[0117] S302: Determine if the torque of the hydraulic retarder is less than 0. If not, proceed to S302; if yes, proceed to S303.

[0118] S303: Shift to the highest gear where the engine speed exceeds the third set speed, then switch to S304;

[0119] S304: Determine if the torque of the hydraulic retarder is equal to 0. If yes, proceed to S305; otherwise, proceed to S306.

[0120] S305: Exit auxiliary braking mode, end;

[0121] S306: Determine if the water temperature of the hydraulic retarder is greater than the temperature limit. If yes, proceed to S307; otherwise, proceed to S303.

[0122] S307: Shift to the highest gear where the engine speed exceeds the fourth set speed, then switch to S303.

[0123] In this invention, when the hydraulic retarder is in gear 2, the step of adjusting the AMT shift range according to the braking power to control the hydraulic retarder at a set temperature includes the following specific steps:

[0124] When the torque of the hydraulic retarder is determined to be less than 0, shift to the highest gear where the engine speed exceeds the fifth set speed.

[0125] Determine if the torque of the hydraulic retarder is equal to 0:

[0126] If not, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds the sixth set speed, then shift to the highest gear where the engine speed exceeds the fifth set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the temperature does not exceed the temperature limit, shift to the highest gear where the engine speed exceeds the fifth set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle.

[0127] If so, then exit the auxiliary braking mode.

[0128] The following combination Figure 5 The following is a detailed explanation of how, when the hydraulic retarder is in gear 2, the AMT shift range is adjusted according to the braking power to control the hydraulic retarder to be at the set temperature.

[0129] S311: Switch the hydraulic retarder to gear 2, then switch to S312;

[0130] S312: Determine if the torque of the hydraulic retarder is less than 0. If not, proceed to S312; if yes, proceed to S313.

[0131] S313: Shift to the highest gear where the engine speed exceeds the fifth set speed, then switch to S314;

[0132] S314: Determine if the torque of the hydraulic retarder is equal to 0. If yes, proceed to S315; otherwise, proceed to S316.

[0133] S315: Exit auxiliary braking mode, end;

[0134] S316: Determine if the water temperature of the hydraulic retarder is greater than the temperature limit. If yes, proceed to S317; otherwise, proceed to S313.

[0135] S317: Shift to the highest gear where the engine speed exceeds the sixth set speed, then switch to S313.

[0136] In this invention, when the hydraulic retarder is in gear 3, the step of adjusting the AMT shift range according to the braking power to control the hydraulic retarder at a set temperature includes the following specific steps:

[0137] When the torque of the hydraulic retarder is determined to be less than 0, shift to the highest gear where the engine speed exceeds the seventh set speed.

[0138] Determine if the torque of the hydraulic retarder is equal to 0:

[0139] If not, then determine whether the braking power of the hydraulic retarder exceeds the power limit:

[0140] If the power is greater than the limit, shift to the highest gear where the engine speed exceeds the ninth set speed, then shift to the highest gear where the engine speed exceeds the seventh set speed, and then check again whether the torque of the hydraulic retarder is equal to 0, and repeat this cycle.

[0141] If the power limit is not exceeded, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds the eighth set speed, then shift to the highest gear where the engine speed exceeds the seventh set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the temperature limit is not exceeded, shift to the highest gear where the engine speed exceeds the seventh set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle.

[0142] The following combination Figure 6 The following is a detailed explanation of how the AMT shift range is adjusted according to the braking power when the hydraulic retarder is in gear 3, so as to control the hydraulic retarder to be at the set temperature.

[0143] S321: Switch the hydraulic retarder to gear 3, then turn to S322;

[0144] S322: Determine if the torque of the hydraulic retarder is less than 0. If not, proceed to S322; if yes, proceed to S323.

[0145] S323: Shift to the highest gear where the engine speed exceeds the seventh set speed, then switch to S324;

[0146] S324: Determine if the torque of the hydraulic retarder is equal to 0. If yes, proceed to S325; otherwise, proceed to S326.

[0147] S325: Exit auxiliary braking mode, end;

[0148] S326: Determine whether the braking power of the hydraulic retarder is greater than the power limit. If yes, proceed to S327; otherwise, proceed to S328.

[0149] S327: Shift to the highest gear where the engine speed exceeds the ninth set speed, then switch to S323;

[0150] S328: Determine if the water temperature of the hydraulic retarder is greater than the temperature limit. If yes, proceed to S329; otherwise, proceed to S323.

[0151] S329: Shift to the highest gear where the engine speed exceeds the eighth set speed, then switch to S323.

[0152] In this invention, the engine speed is controlled within the normal operating speed range for engine braking, and the engine speed is adjusted in real time according to the hydraulic retarder. Specific steps include:

[0153] When the torque of the hydraulic retarder is determined to be less than 0, shift to the highest gear where the engine speed exceeds 1000 rpm;

[0154] Determine if the torque of the hydraulic retarder is equal to 0:

[0155] If not, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds 1250 rpm, then shift to the highest gear where the engine speed exceeds 1000 rpm, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the temperature does not exceed the temperature limit, shift to the highest gear where the engine speed exceeds 1000 rpm, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle.

[0156] If so, then exit the auxiliary braking mode.

[0157] When the auxiliary brake lever is not engaged, the AMT does not receive a signal from the auxiliary brake lever but receives a signal from the hydraulic retarder, indicating that the EBS has activated the auxiliary brake. The AMT ensures that the engine speed is above 1000 rpm, and the engine braking can work normally. The braking power of the hydraulic retarder is above 60%, and the engine speed is generally around 1300 rpm (the engine speed varies slightly for different engines). At this time, the engine noise has little impact on the driver.

[0158] The following combination Figure 7 The document provides a detailed explanation of how to control the engine speed within the normal operating speed range for engine braking, and how to adjust the engine speed in real time based on the hydraulic retarder.

[0159] S401: Auxiliary brake gear is not in position, switch to S402;

[0160] S402: Determine if the torque of the hydraulic retarder is less than 0. If not, proceed to S402; if yes, proceed to S403.

[0161] S403: Shift to the highest gear where the engine speed exceeds 1000 rpm, then switch to S404;

[0162] S404: Determine if the torque of the hydraulic retarder is equal to 0. If yes, proceed to S405; otherwise, proceed to S406.

[0163] S405: Exit auxiliary braking mode, end;

[0164] S406: Determine if the water temperature of the hydraulic retarder is greater than the temperature limit. If yes, proceed to S407; otherwise, proceed to S403.

[0165] S407: Shift to the highest gear where the engine speed exceeds 1250 rpm, then switch to S403.

[0166] For vehicles equipped with AMT (Automated Manual Transmission), a schematic diagram of its auxiliary braking connection principle can be found here. Figure 8 As shown.

[0167] In one possible implementation, if the vehicle lacks an AMT (Automated Manual Transmission), it will not automatically shift gears. If the user does not actively downshift, affecting the auxiliary braking effect, and the braking gear and EBI (Electronic Braking System) of the EBS (Electronic Braking System) are engaged, the driver can use other means to achieve their driving objectives based on the actual situation. If the auxiliary braking constant speed setting leads to speeding or frequent need to control speed by applying the brakes, and the VECU (Vehicle Electronic Control Unit) determines that the AMT's auxiliary braking strategy is insufficient, the instrument panel will remind the driver to "downshift to increase engine speed." For vehicles without AMT, a schematic diagram of the auxiliary braking connection principle can be found in [reference needed]. Figure 9 As shown.

[0168] In the AMT shifting method for auxiliary braking conditions according to this invention, when the AMT controller detects torque in the hydraulic retarder or engine braking, the AMT controller enters the auxiliary braking mode. If the vehicle's auxiliary braking gear has a constant speed function, the auxiliary braking torque is automatically adjusted according to vehicle speed changes to maintain stable vehicle speed. If auxiliary braking is used, the AMT shifting range is determined and corrected according to braking power to control the hydraulic retarder at a set temperature. If the auxiliary braking lever is not engaged, the engine speed is controlled within the normal operating speed range for engine braking, and the engine speed is adjusted in real time according to the hydraulic retarder. That is, by selecting a suitable transmission gear, the engine speed can be increased to ensure the braking effect of engine braking and hydraulic retarder. At the same time, when the auxiliary braking is small, the engine speed is controlled to prevent excessive speed and noise from affecting the driver's experience.

[0169] In one possible implementation, the present invention also provides a non-transitory computer-readable storage medium located in a PLC (Programmable Logic Controller) controller. The storage medium stores a computer program that, when executed by a processor, implements the steps of the AMT shifting method under auxiliary braking conditions described below:

[0170] When the AMT controller detects torque in the hydraulic retarder or engine braking, the AMT controller enters auxiliary braking mode and determines:

[0171] If the vehicle's auxiliary braking gear has a constant speed function, it will automatically adjust the auxiliary braking torque according to changes in vehicle speed to maintain a stable vehicle speed.

[0172] If the auxiliary braking gear is used for auxiliary braking, the AMT shift range is determined and the AMT shift range is adjusted according to the braking power to control the hydraulic retarder at the set temperature.

[0173] If the auxiliary brake lever is not engaged, the engine speed is controlled within the normal operating speed range for engine braking, and the engine speed is adjusted in real time according to the hydraulic retarder.

[0174] Storage media may be any combination of one or more computer-readable media. A computer-readable medium may be a computer-readable signal medium or a computer-readable storage medium. Computer-readable storage media may be, for example, but not limited to, electrical, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatuses, or devices, or any combination thereof. More specific examples (a non-exhaustive list) of computer-readable storage media include: electrical connections having one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof. In this document, a computer-readable storage medium may be any tangible medium that contains or stores a program that can be used by or in conjunction with an instruction execution system, apparatus, or device.

[0175] Computer-readable signal media may include data signals propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals may take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. Computer-readable signal media may also be any computer-readable medium other than computer-readable storage media, capable of transmitting, propagating, or transmitting programs for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium may be transmitted using any suitable medium, including but not limited to: wireless, wireline, optical fiber, RF, etc., or any suitable combination thereof.

[0176] Computer program code for performing the operations of this invention can be written in one or more programming languages ​​or a combination thereof, including object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages—such as the "C" language or similar programming languages. The program code can be executed entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the user's computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0177] An embodiment of the present invention provides an AMT shifting device for auxiliary braking conditions, comprising a judgment module, a first execution module, a second execution module and a third execution module.

[0178] The judgment module is used to activate the AMT controller's auxiliary braking mode when the AMT controller detects torque in the hydraulic retarder or engine braking. If the vehicle's auxiliary braking gear has a constant speed function, it drives the first execution module to work; if the auxiliary braking gear is used for auxiliary braking, it drives the second execution module to work; if the auxiliary braking lever is not engaged, it drives the third execution module to work. The first execution module is used to automatically adjust the auxiliary braking torque according to changes in vehicle speed to maintain stable vehicle speed. The second execution module is used to determine the AMT shift range and correct the AMT shift range according to the braking power to control the hydraulic retarder at the set temperature. The third execution module is used to control the engine speed within the normal operating speed range for engine braking and adjust the engine speed in real time according to the hydraulic retarder.

[0179] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

[0180] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

Claims

1. An AMT shifting method under auxiliary braking conditions, characterized in that, Specifically, the following steps are included: When the AMT controller detects torque in the hydraulic retarder or engine braking, the AMT controller enters auxiliary braking mode and determines: If the vehicle's auxiliary braking gear has a constant speed function, it will automatically adjust the auxiliary braking torque according to changes in vehicle speed to maintain a stable vehicle speed. If the auxiliary braking gear is used for auxiliary braking, the AMT shift range is determined and the AMT shift range is adjusted according to the braking power to control the hydraulic retarder at the set temperature. If the auxiliary brake lever is not engaged, the engine speed is controlled within the normal operating speed range of engine braking, and the engine speed is adjusted in real time according to the hydraulic retarder. The specific steps include controlling the engine speed to be within the normal operating speed range for engine braking, and adjusting the engine speed in real time according to the hydraulic retarder: When the torque of the hydraulic retarder is determined to be less than 0, shift to the highest gear where the engine speed exceeds 1000 rpm; Determine if the torque of the hydraulic retarder is equal to 0: If not, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds 1250 rpm, then shift to the highest gear where the engine speed exceeds 1000 rpm, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the temperature does not exceed the temperature limit, shift to the highest gear where the engine speed exceeds 1000 rpm, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If so, then exit the auxiliary braking mode.

2. The AMT shifting method under auxiliary braking conditions as described in claim 1, characterized in that, The method of automatically adjusting the auxiliary braking torque according to changes in vehicle speed to maintain stable vehicle speed includes the following steps: The vehicle is switched to constant speed gear, and when the hydraulic retarder torque is less than 0, a gear shift operation is performed, shifting to the highest gear where the engine speed exceeds the set minimum speed, and then a check is performed to determine whether the hydraulic retarder torque is equal to 0: If not, shift to the highest gear where the engine speed exceeds the set maximum speed, then gradually reduce the engine speed until the hydraulic retarder torque is equal to 0, and then exit the auxiliary braking mode. If so, then exit the auxiliary braking mode.

3. The AMT shifting method under auxiliary braking conditions as described in claim 2, characterized in that, The process involves shifting to the highest gear where the engine speed exceeds the set maximum speed, then gradually reducing the engine speed until the hydraulic retarder torque equals 0, and then exiting the auxiliary braking mode. Specific steps include: Determine if the vehicle speed exceeds the speed limit: If so, shift to the highest gear where the engine speed exceeds the set maximum speed, then shift to the highest gear where the engine speed exceeds the set minimum speed, and then check again whether the hydraulic retarder torque is equal to 0, and repeat this cycle. If not, then determine whether the braking power of the hydraulic retarder exceeds the power limit: If the power is greater than the limit, shift to the highest gear where the engine speed exceeds the second set speed, then shift to the highest gear where the engine speed exceeds the set minimum speed, and then check again whether the torque of the hydraulic retarder is equal to 0, and repeat this cycle. If the power limit is not exceeded, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds the first set speed, then shift to the highest gear where the engine speed exceeds the set minimum speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the power limit is not exceeded, shift to the highest gear where the engine speed exceeds the set minimum speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. Among them, the maximum speed is set to be greater than the second speed, the second speed is set to be greater than the first speed, and the first speed is set to be greater than the minimum speed.

4. The AMT shifting method under auxiliary braking conditions as described in claim 3, characterized in that, The braking power of the hydraulic retarder is calculated as follows: in, Indicates the braking power of the hydraulic retarder. This represents the torque of the hydraulic retarder. The torque of the hydraulic retarder is equal to the product of the maximum torque of the hydraulic retarder and the percentage of the torque required by the hydraulic retarder. This indicates the rotational speed of the drive shaft.

5. The AMT shifting method under auxiliary braking conditions as described in claim 1, characterized in that: Based on the braking power of the hydraulic retarder, the auxiliary braking of the hydraulic retarder is divided into three levels: level 1, level 2, and level 3. The corresponding engine speed is set according to the auxiliary braking gear of the hydraulic retarder; The first setting of the hydraulic retarder corresponds to the third and fourth set speeds, and the fourth set speed is greater than the third set speed. The hydraulic retarder's second setting corresponds to the fifth and sixth set speeds, with the sixth set speed being greater than the fifth set speed. The three speed settings of the hydraulic retarder correspond to the seventh, eighth, and ninth set speeds, with the ninth set speed being greater than the eighth set speed, and the eighth set speed being greater than the seventh set speed.

6. The AMT shifting method under auxiliary braking conditions as described in claim 4, characterized in that, When the hydraulic retarder is in gear 1, the steps of adjusting the AMT shift range according to the braking power to control the hydraulic retarder at the set temperature include: When the torque of the hydraulic retarder is determined to be less than 0, shift to the highest gear where the engine speed exceeds the third set speed. Determine if the torque of the hydraulic retarder is equal to 0: If not, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds the fourth set speed, then shift to the highest gear where the engine speed exceeds the third set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the temperature does not exceed the temperature limit, shift to the highest gear where the engine speed exceeds the third set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If so, then exit the auxiliary braking mode.

7. The AMT shifting method under auxiliary braking conditions as described in claim 4, characterized in that, When the hydraulic retarder is in gear 2, the AMT shift range is adjusted according to the braking power to control the hydraulic retarder at the set temperature. Specific steps include: When the torque of the hydraulic retarder is determined to be less than 0, shift to the highest gear where the engine speed exceeds the fifth set speed. Determine if the torque of the hydraulic retarder is equal to 0: If not, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds the sixth set speed, then shift to the highest gear where the engine speed exceeds the fifth set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the temperature does not exceed the temperature limit, shift to the highest gear where the engine speed exceeds the fifth set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If so, then exit the auxiliary braking mode.

8. The AMT shifting method under auxiliary braking conditions as described in claim 4, characterized in that, When the hydraulic retarder is in gear 3, the AMT shift range is adjusted according to the braking power to control the hydraulic retarder at the set temperature. Specific steps include: When the torque of the hydraulic retarder is determined to be less than 0, shift to the highest gear where the engine speed exceeds the seventh set speed. Determine if the torque of the hydraulic retarder is equal to 0: If not, then determine whether the braking power of the hydraulic retarder exceeds the power limit: If the power is greater than the limit, shift to the highest gear where the engine speed exceeds the ninth set speed, then shift to the highest gear where the engine speed exceeds the seventh set speed, and then check whether the torque of the hydraulic retarder is equal to 0 again, and repeat this cycle. If the power limit is not exceeded, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds the eighth set speed, then shift to the highest gear where the engine speed exceeds the seventh set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the temperature limit is not exceeded, shift to the highest gear where the engine speed exceeds the seventh set speed, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle.

9. An AMT shifting device for auxiliary braking conditions, characterized in that, include: The judgment module is used to enter the auxiliary braking mode when the AMT controller detects that there is torque in the hydraulic retarder or engine braking. If the vehicle's auxiliary braking gear has a constant speed function, the first execution module is driven to work. If the auxiliary braking gear is used for auxiliary braking, the second execution module is driven to work. If the auxiliary braking lever is not opened, the third execution module is driven to work. The first execution module is used to automatically adjust the auxiliary braking torque according to changes in vehicle speed to maintain stable vehicle speed; The second execution module is used to determine the AMT shift range and correct the AMT shift range according to the braking power in order to control the hydraulic retarder to be at the set temperature. The third execution module is used to control the engine speed within the normal operating speed range of engine braking, and to adjust the engine speed in real time according to the hydraulic retarder. The specific steps include controlling the engine speed to be within the normal operating speed range for engine braking, and adjusting the engine speed in real time according to the hydraulic retarder: When the torque of the hydraulic retarder is determined to be less than 0, shift to the highest gear where the engine speed exceeds 1000 rpm; Determine if the torque of the hydraulic retarder is equal to 0: If not, check if the hydraulic retarder coolant temperature exceeds the temperature limit. If it does, shift to the highest gear where the engine speed exceeds 1250 rpm, then shift to the highest gear where the engine speed exceeds 1000 rpm, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If the temperature does not exceed the temperature limit, shift to the highest gear where the engine speed exceeds 1000 rpm, and then check if the hydraulic retarder torque is equal to 0 again, and repeat this cycle. If so, then exit the auxiliary braking mode.

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