A traction force automatic control system and method of an articulated dump truck, and an articulated dump truck

Abstract

The application provides a kind of articulated dump truck traction automatic control method and system, articulated dump truck, the method comprises: judging whether articulated dump truck slip occurs;The slip includes drive axle slip and wheel slip;Vehicle attitude data of articulated dump truck is monitored;Attitude data includes: vehicle steering angle, longitudinal slope and transverse slope inclination of vehicle front frame, transverse slope inclination of rear frame;According to whether articulated dump truck slip occurs, vehicle attitude, on-off button signal, engine speed and driver operation determines whether to enable, keep and release traction force distribution control;The traction force distribution control is executed by controlling brake proportional solenoid valve, power output torque, engine speed and differential lock solenoid valve group.The application can automatically lock and release differential lock according to the slip condition between wheels and drive axle, adjust vehicle traction torque, ensure that each wheel has suitable traction, realize vehicle automatic off-road.

Description

Technical Field

[0001] This invention belongs to the field of driving assistance systems for construction machinery, and can be further classified into the field of electronic control technology for construction machinery chassis. In particular, it relates to an automatic traction control system and method for an articulated dump truck, and the articulated dump truck itself. Background Technology

[0002] Articulated dump trucks feature independent front and rear frames and often employ four-wheel or six-wheel drive, giving them exceptional off-road capabilities. Even so, on wet and slippery surfaces, articulated dump trucks can still experience wheel slippage, vehicle spin, and even become stuck. In such situations, the driver needs to apply the differential lock under specific conditions to prevent slippage and extricate the vehicle. However, if the driver applies the differential lock at the wrong time or depresses the brake or accelerator pedals, it may not only fail to extricate the vehicle but could also cause transmission system malfunctions, accelerate wheel wear, and excessively increase fuel consumption.

[0003] Therefore, there is an urgent need for an automatic traction control method for articulated dump trucks to solve the problem of vehicle slippage in articulated dump trucks. Summary of the Invention

[0004] The purpose of this invention is to provide an automatic traction control method and system for an articulated dump truck, and an articulated dump truck, to solve the above-mentioned problems.

[0005] This invention is implemented according to the following technical solution:

[0006] In a first aspect, the present invention provides an automatic traction control method for an articulated dump truck, the method comprising the following steps: determining whether the articulated dump truck is slipping; the slipping includes drive axle slippage and wheel slippage;

[0007] The vehicle attitude data of the articulated dump truck is monitored; the attitude data includes: vehicle steering angle, longitudinal and transverse slope angles of the front frame, and transverse slope angle of the rear frame.

[0008] The traction distribution control is activated, maintained, and deactivated based on factors such as whether the articulated dump truck slips, vehicle posture, switch button signals, engine speed, retarder activation status, and brake pedal position. The traction distribution control is executed by controlling the brake proportioning solenoid valve, power output torque, engine speed, and differential lock solenoid valve group.

[0009] In one embodiment, drive axle slippage refers to the phenomenon that the rotational speeds of the front drive axle input shaft, rear drive axle input shaft, and gearbox output shaft are inconsistent after removing the influence of rotational angle; wheel slippage refers to the phenomenon that the rotational speeds of the left and right wheels relative to the ground are inconsistent; wheel slippage will cause drive axle slippage as a result.

[0010] In one embodiment, determining whether the articulated dump truck has slipped includes:

[0011] The ratio of the front and rear output shaft speeds of the transfer case, k, is derived from the speed of the gearbox output shaft and the speed of the transfer case output shaft.

[0012] Preset minimum threshold k for transfer case output shaft speed ratio min and maximum threshold k max The threshold compensation variable Δk0 is proportional to the difference in cross slope angle; when the value of k is less than k min -Δk0, or k value greater than k max If +Δk0, it is considered that the drive axle is slipping;

[0013] The output shaft speed of the transfer case needs to be compared with a preset threshold after removing the influence of turning.

[0014] The actual moving speed v of the vehicle is estimated by combining the Global Positioning System (GPS) with inertial measurement. p ;

[0015] The wheel-to-ground speed v is calculated based on the gearbox output speed, the transmission ratios of various vehicle components, and the wheel radius parameters. g ;

[0016] The difference between the ground speed and the estimated actual speed of the vehicle is Δv;

[0017] A preset speed difference threshold Δv1 and a threshold compensation variable Δv0 that is proportional to the difference in cross slope angle are used. When Δv is greater than Δv1 - Δv0, wheel slippage or drive axle slippage is determined.

[0018] In one embodiment, the traction distribution includes transfer case traction distribution and wheel traction distribution;

[0019] The activation conditions for the transfer case traction distribution include: the drive axle slipping, the steering angle being lower than a preset threshold θ1, and the brakes not being activated; or the drive axle slipping, the steering angle being lower than a preset threshold, the brakes being activated, and the vehicle speed being presumed to be lower than a preset threshold; or the transfer case differential lock button being active; or the full differential lock button being active.

[0020] The activation conditions for the wheel traction distribution include: the transfer case differential lock GD being activated; the estimated vehicle speed and the difference between the wheel speed and the ground speed Δv being greater than the threshold Δv1-Δv0, i.e., wheel slippage; or the full differential lock button being active.

[0021] The conditions for maintaining the transfer case traction distribution include: the transfer case differential lock GD being engaged, and the vehicle's longitudinal slope angle i. l Greater than the preset threshold i l0Or the speed difference of the drive axle is still large, (1+β)*(k min -Δk0) <K<(1+β)*(k max +Δk0), where β is a preset proportional parameter;

[0022] The conditions for maintaining the wheel traction distribution include: the inter-wheel differential locks FD, CD, and RD are enabled; the estimated difference between the vehicle speed and the wheel speed relative to the ground Δv is less than the threshold (1-γ)*(Δv1-Δv0); and the full differential lock button is disabled, where γ is a pre-set proportional parameter γ.

[0023] The condition for releasing the traction force distribution is that the condition for maintaining the traction force distribution is no longer met.

[0024] In one embodiment, the switch button signals include: transfer case differential lock switch signal, full differential switch signal, and ATC system switch signal; the maximum operating time of the full differential switch is limited, and the amount of change in its operating time increases or decreases with the change in the difference in the cross slope angle between the front and rear frames.

[0025] In one embodiment, the differential lock solenoid valve group includes: a transfer case differential lock solenoid valve GD and an inter-axle differential lock solenoid valve; the inter-axle differential lock solenoid valve includes: a front axle inter-axle differential lock FD, a first rear axle inter-axle differential lock CD, and an Nth rear axle inter-axle differential lock RD; the transfer case differential lock solenoid valve is located inside the transfer case and is used to lock the differential device of the front and rear output shafts of the transfer case. When the transfer case differential lock is locked, the output speeds of its front and rear output shafts are the same; the activation of the transfer case differential lock takes priority over the inter-axle differential lock, and the deactivation of the inter-axle differential lock takes priority over the transfer case differential lock.

[0026] In one implementation, in the traction distribution execution section, if the vehicle is braking, the traction force is controlled according to the vehicle's slippage, and the transfer case differential lock is activated; at the same time, to avoid vehicle jerking, the transfer case differential lock will not be released until a certain period of time after the vehicle has come to a complete stop; if the vehicle is in driving mode, the system will limit the engine torque during the differential lock holding process to prevent excessive driving force from causing vehicle slippage; if the difference in lateral tilt angle between the front and rear frames of the vehicle is large, the traction control distribution time is extended, and the conditions for releasing the traction control distribution are increased.

[0027] In one embodiment, the method for removing the influence of turning is as follows: the theoretical speed difference during turning is calculated based on the steering angle and the vehicle frame size and layout position, and its influence is eliminated during the slip judgment.

[0028] Secondly, this invention proposes an automatic traction control system for an articulated dump truck, characterized in that: the system includes:

[0029] The vehicle attitude monitoring unit is used to monitor the vehicle attitude of the articulated dump truck; the attitude data includes: vehicle steering angle, longitudinal and transverse slope angles of the front frame, and transverse slope angle of the rear frame.

[0030] The slippage detection unit is used to determine whether the articulated dump truck has slipped; the slippage includes drive axle slippage and wheel slippage;

[0031] The control and judgment unit is used to determine whether to activate, maintain, and deactivate traction distribution control based on the vehicle's attitude, whether slippage has occurred, the status of the switch buttons, the engine speed provided by the engine controller, the retarder activation status provided by the retarder controller, and the brake pedal.

[0032] The traction force distribution execution unit is used to distribute traction force by controlling the brake proportioning solenoid valve, power output torque, engine speed, and differential lock solenoid valve group according to the instructions issued by the control judgment unit.

[0033] Thirdly, the present invention provides an articulated dump truck having independent front and rear frames connected by an articulated body, and the articulated dump truck is equipped with the aforementioned automatic traction control system for articulated dump trucks.

[0034] Beneficial effects of this invention:

[0035] This invention can automatically lock and release the differential lock according to the slippage between the wheels and the drive axle, adjust the vehicle's traction torque, ensure that each wheel has appropriate traction, and realize the vehicle's automatic off-road capability. Attached Figure Description

[0036] The accompanying drawings, as part of this invention, are provided to further illustrate the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation thereof. Clearly, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0037] Figure 1 A flowchart of an automatic traction control method for an articulated dump truck according to an embodiment of the present invention;

[0038] Figure 2 A block diagram of an automatic traction control system for an articulated dump truck according to an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram of an articulated dump truck structure provided in an embodiment of the present invention;

[0040] Figure 4This is a flowchart illustrating the start-up, holding, and release control of the transfer case differential electromagnetic lock and the inter-wheel differential lock according to an embodiment of the present invention.

[0041] Explanation of reference numerals in the attached diagram: E - engine or other power unit; T - transmission; SS - transfer case output shaft speed sensor; AS - articulated body angle sensor; B - brake disc; FD - front axle wheel differential lock; FSA - transfer case front output shaft; G - transfer case; GD - transfer case differential lock; RSA - transfer case rear output shaft; CD - first rear axle wheel differential lock; RD - Nth rear axle wheel differential lock.

[0042] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0044] Reference Figure 1 As shown, the present invention provides a control method for an automatic traction control system, which is applied to an articulated dump truck, and specifically includes the following steps:

[0045] Step S100: Determine whether the articulated dump truck has slipped; the slippage includes drive axle slippage and wheel slippage.

[0046] Drive axle slip refers to the phenomenon where the rotational speeds of the front drive axle input shaft, rear drive axle input shaft, and gearbox output shaft are inconsistent after removing the influence of rotational angle; wheel slip refers to the phenomenon where the rotational speeds of the left and right wheels relative to the ground are inconsistent; wheel slip can lead to drive axle slip.

[0047] In this embodiment of the application, determining whether the articulated dump truck has slipped includes:

[0048] The ratio of the front and rear output shaft speeds of the transfer case, k, is derived from the speed of the gearbox output shaft and the speed of the transfer case output shaft.

[0049] Preset minimum threshold k for transfer case output shaft speed ratio min and maximum threshold k max The threshold compensation variable Δk0 is proportional to the difference in cross slope angle; when the value of k is less than k min -Δk0, or k value greater than k max If +Δk0, it is considered that the drive axle is slipping;

[0050] The output shaft speed of the transfer case needs to be compared with a preset threshold after removing the influence of turning.

[0051] The actual moving speed v of the vehicle is estimated by combining the Global Positioning System (GPS) with inertial measurement. p ;

[0052] The wheel-to-ground speed v is calculated based on the gearbox output speed, the transmission ratios of various vehicle components, and the wheel radius parameters. g ;

[0053] The difference between the ground speed and the estimated actual speed of the vehicle is Δv;

[0054] A preset speed difference threshold Δv1 and a threshold compensation variable Δv0 that is proportional to the difference in cross slope angle are used. When Δv is greater than Δv1 - Δv0, wheel slippage or drive axle slippage is determined.

[0055] It should be noted that wheel slippage can cause drive axle slippage. In rare special cases, both wheels may slip simultaneously but at roughly the same speed. However, since drive axle slippage is not a reliable indicator of wheel slippage or drive axle slippage based solely on vehicle speed difference, it's impossible to distinguish between wheel slippage and drive axle slippage. However, when the transfer case differential lock is engaged, the drive axle speeds become identical, and a speed difference still exists, indicating wheel slippage.

[0056] The transfer case has outputs at both ends and an input at the front. A speed sensor monitors the speed of one output shaft, and the input speed is the same as the output speed of the transmission. The speed of the other output shaft is calculated based on the law of conservation of energy. The output shaft speed ratio of the transfer case needs to be adjusted to remove the influence caused by turning before it can be compared with a preset threshold to determine whether the drive axle is slipping.

[0057] Furthermore, the method to eliminate the influence of turning is to calculate the theoretical speed difference during turning based on the steering angle and the vehicle frame size and layout, and then eliminate its influence when judging slippage.

[0058] Reference Figure 2 As shown, the transfer case output shaft speed n1 is obtained from the transfer case output shaft speed sensor, and then combined with the transmission output shaft speed obtained from the transmission controller, i.e., the transfer case input shaft speed n3. Since the transfer case is a planetary gear mechanism, the other end output shaft speed n2 of the transfer case can be obtained according to formula (1). For ease of demonstration, in this invention, n1 is taken as the rear output shaft speed of the transfer case, and n2 is taken as the front output shaft speed of the transfer case.

[0059] n1+αn2=(1+α)n3 (1)

[0060] Where α is the gear ratio between the transfer case gear ring and the sun gear.

[0061] A single-axis horizontal tilt sensor measures the lateral tilt angle i of the rear frame. rc IMU measures the lateral slope angle i of the front frame. fc and vehicle longitudinal slope angle il The difference in cross slope angle between the front and rear frames Δi c It is obtained from formula (2).

[0062] Δi c -|i rc -i fc | (2)

[0063] The steering angle sensor monitors the vehicle's steering angle θ and presets a minimum threshold k for the transfer case output shaft speed ratio. min Maximum threshold k max The value of Δk0 is related to Δi c The speed ratio k of the front and rear output shafts of the transfer case is proportional to the speed of the transfer case, which is obtained by formula (3).

[0064]

[0065] Among them, L f L is the distance from the physical center point of the articulated joint to the front frame pin to the physical midpoint of the front axle. f This is the distance from the physical center point of the articulated joint's connection to the front frame pin to the physical midpoint of the first rear axle. When the value of k is less than k... min -Δk0, or k value greater than k max If +Δk0, it is considered that the drive axle is slipping.

[0066] In addition, the estimated vehicle speed v is obtained by combining GPS and IMU with Kalman filtering. p The wheel-to-ground speed v is calculated based on parameters such as the gearbox output speed, the transmission ratios of various vehicle components, and the wheel radius. g The preset speed difference threshold Δv1 and Δv0 are threshold compensation variables, and are related to Δi. c It is directly proportional. When Δv is greater than Δv1-Δv0, it is determined that the drive axle is slipping or the wheel is slipping.

[0067] Δv=v g -v p (4)

[0068] Step S200: Monitor the vehicle attitude data of the articulated dump truck; the attitude data includes: vehicle steering angle, longitudinal and transverse slope angles of the front frame, and transverse slope angle of the rear frame.

[0069] In this embodiment, the steering angle of the vehicle attitude monitoring unit is monitored by an angle sensor located at the articulation point. This angle sensor is fixed to the articulation point with the rear frame, and the connecting rod is connected to the front frame. The angle of change of the connecting rod is the vehicle steering angle. The longitudinal slope and lateral slope angle of the front frame of the vehicle attitude monitoring unit are monitored by an inertial measurement unit, and the lateral slope angle of the rear frame is monitored by a single-axis horizontal tilt sensor.

[0070] Step S300: Determine whether to activate, maintain, and deactivate traction force distribution control based on whether the articulated dump truck slips, vehicle posture, switch button signal, engine speed, retarder activation status, and brake pedal; the traction force distribution control is executed by controlling the brake proportional solenoid valve, power output torque, engine speed, and differential lock solenoid valve group.

[0071] In this embodiment, traction distribution includes transfer case traction distribution and wheel traction distribution.

[0072] The activation conditions for transfer case traction distribution include: drive axle slippage, steering angle below a preset threshold θ1, and brakes not activated; or drive axle slippage, steering angle below a preset threshold, brakes activated, and vehicle speed presumed to be below a preset threshold; or transfer case differential lock button active; or full differential lock button active.

[0073] The conditions for activating wheel traction distribution include: the transfer case differential lock GD being activated; the difference between the estimated vehicle speed and the wheel speed relative to the ground Δv being greater than the threshold Δv1-Δv0, i.e., wheel slippage; or the full differential lock button being active.

[0074] Conditions for maintaining transfer case traction distribution: including transfer case differential lock GD being engaged, and vehicle longitudinal slope angle i. l Greater than the preset threshold i l0 ;

[0075] Or the speed difference of the drive axle is still large, (1+β)*(k min -Δk0) <K<(1+β)*(k max +Δk0), where β is a preset proportional parameter.

[0076] Conditions for maintaining wheel traction distribution: inter-wheel differential locks FD, CD, and RD are enabled, the estimated vehicle speed and wheel-to-ground speed difference Δv is less than the threshold (1-γ)*(Δv1-Δv0), and the full differential lock button is disabled, where γ is a pre-set proportional parameter γ.

[0077] Condition for disengaging traction distribution: The conditions for maintaining traction distribution are no longer met.

[0078] Furthermore, the switch button signals include: transfer case differential lock switch signal, full differential switch signal, and ATC system switch signal; the maximum operating time of the full differential switch is limited, and its operating time varies with the difference in the cross slope angle between the front and rear frames.

[0079] Furthermore, the differential lock solenoid valve assembly includes: the transfer case differential lock solenoid valve GD and the inter-axle differential lock solenoid valve;

[0080] The inter-axle differential lock solenoid valve includes: a front axle inter-axle differential lock FD, a first rear axle inter-axle differential lock CD, and an Nth rear axle inter-axle differential lock RD; the transfer case differential lock solenoid valve is located inside the transfer case and is used to lock the differential device of the front and rear output shafts of the transfer case. When the transfer case differential lock is locked, the output speeds of its front and rear output shafts are the same; the activation of the transfer case differential lock takes priority over the inter-axle differential lock, and the deactivation of the inter-axle differential lock takes priority over the transfer case differential lock.

[0081] Furthermore, in the traction distribution execution section, if the vehicle is braking, the traction force is controlled according to the vehicle's slippage, and the transfer case differential lock is activated. At the same time, to avoid vehicle jerking, the transfer case differential lock will not be released until a certain period of time after the vehicle has come to a complete stop. If the vehicle is in driving mode, the system will limit the engine torque during the differential lock holding process to prevent excessive driving force and vehicle slippage. If the difference in lateral tilt angle between the front and rear frames of the vehicle is large, the traction control distribution time is extended, and the conditions for releasing the traction control distribution are increased.

[0082] like Figure 2 As shown, this invention proposes an automatic traction control system for an articulated dump truck. The system includes: a vehicle attitude monitoring unit, a control judgment unit, and a traction force distribution execution unit.

[0083] The vehicle attitude monitoring unit is used to monitor the vehicle attitude of the articulated dump truck; the attitude data includes: vehicle steering angle, longitudinal and transverse slope angles of the front frame, and transverse slope angle of the rear frame.

[0084] The slippage detection unit is used to determine whether the articulated dump truck has slipped; the slippage includes drive axle slippage and wheel slippage;

[0085] Drive axle slip refers to the phenomenon where the rotational speeds of the front drive axle input shaft, rear drive axle input shaft, and transmission output shaft are inconsistent after removing the influence of steering angle. Wheel slip refers to the phenomenon where the rotational speeds of the left and right wheels relative to the ground are inconsistent, and wheel slip generally also leads to drive axle slip. Vehicle turning can cause drive axle slip or wheel slip. The theoretical speed difference during turning is calculated based on the steering angle and the vehicle frame dimensions and layout, and its influence is eliminated during slip detection. Drive axle slip is mainly monitored by the transmission output speed sensor and the transfer case output shaft speed sensor, without needing to detect wheel speed. The estimated vehicle speed can be obtained using GPS and IMU combined with Kalman filtering. Wheel speed relative to the ground is calculated based on parameters such as transmission output speed, transfer case transmission ratio, axle ratio, and wheel radius. The wheel speed relative to the ground is compared with the estimated vehicle speed, and the difference is calculated. When the difference exceeds a preset threshold, vehicle slip is determined. The specific judgment method is described in the embodiment of the automatic traction control method for articulated dump trucks.

[0086] The control and judgment unit is used to determine whether to activate, maintain, and deactivate traction distribution control based on the vehicle's attitude, whether slippage has occurred, the status of the switch buttons, the engine speed provided by the engine controller, the retarder activation status provided by the retarder controller, and the brake pedal.

[0087] The traction force distribution execution unit is used to distribute traction force by controlling the brake proportioning solenoid valve, power output torque, engine speed, and differential lock solenoid valve group according to the instructions issued by the control judgment unit.

[0088] Furthermore, the system determines whether the execution is in place based on feedback from each pressure sensor and displays the execution status on a monitor or instrument.

[0089] It should be noted that the automatic traction control system for the articulated dump truck provided in the above embodiments is only illustrated by the division of the functional modules described above when executing the automatic traction control method for the articulated dump truck. In practical applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the equipment can be divided into different functional modules to complete all or part of the functions described above. In addition, the automatic traction control system for the articulated dump truck provided in the above embodiments and the automatic traction control method embodiments for the articulated dump truck belong to the same concept, and its implementation process is detailed in the automatic traction control method embodiments for the articulated dump truck, which will not be repeated here.

[0090] Reference Figure 3 As shown, in one embodiment, an articulated dump truck is proposed, which includes the control system described above.

[0091] The articulated dump truck has independent front and rear frames connected by an articulation mechanism. Power is supplied by a power unit E, and after speed and torque are changed by a transmission T, the transfer case G distributes the torque to the front output shaft FSA and the rear output shaft RSA. The front output shaft FSA distributes the torque to the left and right wheels of the front axle via a driveshaft and the front axle differential. The rear output shaft RSA distributes the torque to the first rear axle differential and the Nth rear axle differential via a driveshaft, and then distributes it to the left and right wheels of each axle via the differential. Furthermore, the rear axles are directly connected to each other. All rear axle wheels are equipped with brake discs B, providing braking force. This braking force is controlled by an electromagnetic proportional valve in the hydraulic system. The transfer case transmits power to the front and rear drive axles via the front and rear output shafts. Here, "rear drive axle" does not refer to a single drive axle, but rather to one, two, or even more connected drive axles. The articulated dump truck is equipped with a transfer case differential lock solenoid valve GD, a front axle wheel differential lock FD, a first rear axle wheel differential lock CD, and an Nth rear axle wheel differential lock RD. Figure 4The control flowcharts for starting, holding, and releasing the transfer case differential electromagnetic lock and the inter-wheel differential lock are given.

[0092] The following describes the process of activating, maintaining, and deactivating traction distribution control for articulated dump trucks.

[0093] Preset vehicle speed threshold v p0 When drive axle slippage is detected, and the steering angle θ is lower than the preset threshold θ1, and the brakes are not activated; or when drive axle slippage is detected, and the steering angle is lower than the preset threshold θ1, and the brakes are activated, the estimated vehicle speed v is determined. p Below the threshold v p0 If the transfer case differential lock button is active, or the full differential lock button is active, then the transfer case position differential lock (GD) will be activated.

[0094] Preset longitudinal slope angle threshold i l0 The proportional parameter β, when the transfer case differential lock GD is engaged, the vehicle's longitudinal slope angle i l Greater than threshold i l0 , or (1+β)*(k min -Δk0) <K<(1+β)*(k max If +Δk0), the transfer case differential lock GD remains locked; otherwise, the transfer case differential lock GD is released.

[0095] When the transfer case differential lock GD is activated, it is assumed that the difference between the vehicle speed and the wheel speed relative to the ground is greater than the threshold Δv1-Δv0, i.e., wheel slippage; or the full differential lock button is valid; the inter-wheel differential locks FD, CD, and RD are activated.

[0096] The proportional parameter γ is preset. When the inter-wheel differential locks FD, CD, and RD are enabled, the estimated difference between the vehicle speed and the wheel speed relative to the ground Δv is less than the threshold (1-γ)*(Δv1-Δv0), and the full differential lock button is disabled, the inter-wheel differential locks FD, CD, and RD are released. Otherwise, the inter-wheel differential locks FD, CD, and RD are maintained.

[0097] When differential locks GD, FD, CD, and RD are engaged, they limit engine torque and transmission output speed. The maximum torque limit is obtained when the difference between the estimated vehicle speed and the wheel speed relative to the ground is at its minimum and the difference between the front and rear speeds of the drive axle is at its minimum. When the differential lock is disengaged, the maximum torque limit is no longer applied.

[0098] During the activation and deactivation of differential locks GD, FD, CD, and RD, the accelerator pedal is automatically disabled. Braking is applied through the brake proportioning valve, first reducing the engine speed and vehicle speed to the corresponding values. After activation or deactivation, the engine speed and torque are gradually increased, and finally, under the premise of meeting the limit values, the accelerator pedal is returned to control.

[0099] The preset cross slope angle difference threshold is i2, and the maximum effective time for the full differential manual button is t1. When monitoring the cross slope angle difference Δi between the front and rear frames... c If the threshold i2 is not exceeded, the extension time is t1 + Δt, and the value of Δt is related to the tilt angle difference Δi. c Related.

[0100] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0101] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features found in other embodiments but not others, combinations of features from different embodiments are also within the scope of protection of this invention and form different embodiments. For example, in the embodiments described above, those skilled in the art can use them in combination based on known technical solutions and the technical problems to be solved by this application.

[0102] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An automatic traction control method for an articulated dump truck, characterized in that: The method includes: Determine whether the articulated dump truck has experienced slippage; the slippage includes drive axle slippage and wheel slippage; The vehicle attitude data of the articulated dump truck is monitored; the attitude data includes: vehicle steering angle, longitudinal and transverse slope angles of the front frame, and transverse slope angle of the rear frame. The traction distribution control is activated, maintained, and deactivated based on whether the articulated dump truck slips, vehicle posture, switch button signals, engine speed, retarder activation status, and brake activation status. The switch button signals include: transfer case differential lock switch signal, full differential switch signal, and ATC system switch signal. The traction distribution control is executed by controlling the brake proportional solenoid valve, power output torque, engine speed, and differential lock solenoid valve group.

2. The automatic traction control method for an articulated dump truck according to claim 1, characterized in that: The drive axle slip refers to the phenomenon that the rotational speeds of the front drive axle input shaft, the rear drive axle input shaft, and the gearbox output shaft are inconsistent after removing the influence of rotational angle. The wheel slippage refers to the phenomenon that the left and right wheels rotate at different speeds relative to the ground; the wheel slippage will also cause the drive axle to slip.

3. The automatic traction control method for an articulated dump truck according to claim 2, characterized in that: The determination of whether the articulated dump truck has slipped includes: The ratio of the front and rear output shaft speeds of the transfer case, k, is derived from the speed of the gearbox output shaft and the speed of the transfer case output shaft. Preset minimum threshold k for transfer case output shaft speed ratio min and maximum threshold k max The threshold compensation variable Δk0 is proportional to the difference between the cross slope angles of the front and rear frames; when the value of k is less than k min -Δk0, or k value greater than k max If +Δk0, the drive axle is considered to be slipping; the output shaft speed of the transfer case needs to be compared with a preset threshold after removing the influence of turning. The actual moving speed v of the vehicle is estimated by combining the Global Positioning System (GPS) with inertial measurement. p ; The wheel speed relative to the ground, v, is calculated based on the gearbox output speed, the transmission ratios of various vehicle components, and the wheel radius parameters. g ; The difference between the wheel's speed relative to the ground and the estimated actual speed of the vehicle is Δv; The preset speed difference threshold Δv1 and the threshold compensation variable Δv0 are proportional to the difference between the cross slope angles of the front frame and the rear frame. When Δv is greater than Δv1 - Δv0, it is determined that the wheel slips or the drive axle slips.

4. The automatic traction control method for an articulated dump truck according to claim 1, characterized in that: The traction force distribution control includes transfer case traction force distribution control and wheel traction force distribution control; The activation conditions for the transfer case traction force distribution include: detecting drive axle slippage, and the steering angle being lower than a preset steering angle threshold θ1, and the brakes not being activated; Alternatively, the drive axle may slip and the steering angle may be lower than the preset steering angle threshold θ1, in which case the brakes may be activated, and the actual vehicle speed may be lower than the preset actual vehicle speed threshold; or the transfer case differential lock button may be active; or the full differential lock button may be active. The activation conditions for the wheel traction distribution include: the transfer case differential lock GD being activated, and the estimated difference between the vehicle speed and the wheel speed relative to the ground Δv being greater than the threshold Δv1-Δv0, i.e., wheel slippage. Alternatively, the full differential lock button may be active; The conditions for maintaining the transfer case traction distribution include: the transfer case differential lock GD being engaged, and the vehicle's longitudinal slope angle i. l Greater than the preset threshold i l0 ; or the speed ratio of the front and rear output shafts of the transfer case is still within the preset range, (1+β)*( k min Δk0)< k <(1+β)*(k max +Δk0), where β is a preset proportional parameter; The conditions for maintaining the wheel traction distribution are: the inter-wheel differential locks FD, CD, and RD are enabled, the estimated difference between the vehicle speed and the wheel speed relative to the ground Δv is less than the threshold (1-γ)*(Δv1-Δv0), and the full differential lock button is disabled, where γ is a preset proportional parameter; The condition for releasing the traction force distribution is that the condition for maintaining the traction force distribution is no longer met.

5. The automatic traction control method for an articulated dump truck according to claim 1, characterized in that: The switch button signals include: transfer case differential lock switch signal, full differential switch signal, and ATC system switch signal; the maximum operating time of the full differential switch is limited, and its operating time varies with the difference in the cross slope angle between the front and rear frames.

6. The automatic traction control method for an articulated dump truck according to claim 1, characterized in that: The differential lock solenoid valve group includes: transfer case differential lock solenoid valve GD and inter-axle differential lock solenoid valve; The inter-axle differential lock solenoid valve includes: a front axle inter-axle differential lock FD, a first rear axle inter-axle differential lock CD, and an Nth rear axle inter-axle differential lock RD; the transfer case differential lock solenoid valve is located inside the transfer case and is used to lock the differential device of the front and rear output shafts of the transfer case. When the transfer case differential lock is locked, the output speeds of its front and rear output shafts are the same; the activation of the transfer case differential lock takes priority over the inter-axle differential lock, and the deactivation of the inter-axle differential lock takes priority over the transfer case differential lock.

7. The automatic traction control method for an articulated dump truck according to claim 1, characterized in that: In the traction distribution execution section, if the vehicle is braking, the traction force is controlled according to the vehicle's slippage, and the transfer case differential lock is activated; at the same time, in order to avoid the vehicle jerking, the transfer case differential lock will not be released until a certain period of time after the vehicle has come to a complete stop; if the vehicle is in driving mode, the system will limit the engine torque during the differential lock holding process to prevent excessive driving force and vehicle slippage. If the difference in lateral tilt angle between the front and rear frames of the vehicle exceeds the preset lateral tilt angle difference threshold, the traction control distribution time will be extended, and the conditions for releasing the traction control distribution will be increased.

8. The automatic traction control method for an articulated dump truck according to claim 3, characterized in that: The method for removing the effects of turning is as follows: calculate the theoretical speed difference during turning based on the steering angle and the vehicle frame size and layout, and eliminate its effects when judging slippage.

9. An automatic traction control system for an articulated dump truck, characterized in that: The system includes: The vehicle attitude monitoring unit is used to monitor the vehicle attitude of the articulated dump truck; the attitude data includes: vehicle steering angle, longitudinal and transverse slope angles of the front frame, and transverse slope angle of the rear frame. The slippage detection unit is used to determine whether the articulated dump truck has slipped; the slippage includes drive axle slippage and wheel slippage; The control and judgment unit is used to determine whether to activate, maintain, and deactivate traction distribution control based on the vehicle's attitude, whether slippage has occurred, switch button signals, engine speed provided by the engine controller, and retarder activation and brake activation status provided by the retarder controller; the switch button signals include: transfer case differential lock switch signal, full differential switch signal, and ATC system switch signal; The traction force distribution execution unit is used to distribute traction force by controlling the brake proportioning solenoid valve, power output torque, engine speed, and differential lock solenoid valve group according to the instructions issued by the control judgment unit.

10. An articulated dump truck, comprising independent front and rear frames connected by an articulated body, characterized in that: The articulated dump truck is equipped with the automatic traction control system of the articulated dump truck as described in claim 9.

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