A large horsepower tractor acceleration dynamic adjustment method

Abstract

The application discloses a large-horsepower tractor acceleration dynamic adjustment method, which comprises the following steps: controlling the requested vehicle acceleration through a transmission ratio difference; controlling the requested vehicle downshift deceleration during a change in the driving direction; and controlling the requested vehicle downshift deceleration when the vehicle is decelerating or if a foot brake is activated. The final requested acceleration is selected from the above-mentioned several kinds of dynamically adjusted accelerations, so that the impact effect caused by gear shifting is reduced, and the vehicle stability during vehicle driving is greatly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of speed regulation, and particularly relates to a large-horsepower tractor acceleration dynamic regulation method. BACKGROUND

[0002] The drive train of a high-end intelligent large-horsepower tractor adopts a mechanical-hydraulic continuously variable transmission, which is a power coupling of a mechanical flow and a hydraulic flow at a double planetary gear set to realize continuously variable transmission,

[0003] Due to mechanical gear switching, in a certain transmission ratio range, the actual transmission ratio realized by the power coupling of the mechanical flow and the hydraulic flow has a large deviation from the expected transmission ratio, especially when switching from mechanical 1st gear to 2nd gear or from 2nd gear to 1st gear, which will cause a certain impact effect, i.e., the vehicle speed changes sharply, the stability of vehicle driving is poor, and the driver's driving experience is poor. SUMMARY

[0004] The application aims to provide a large-horsepower tractor acceleration dynamic regulation method to overcome the problem of poor stability of vehicle driving of the prior art large-horsepower tractor in various operating environments.

[0005] To solve the above problem, the application adopts the following scheme:

[0006] A large-horsepower tractor acceleration dynamic regulation method comprises the following processes:

[0007] controlling the requested vehicle acceleration through the transmission ratio difference; controlling the requested vehicle downshift deceleration during a change in driving direction; and controlling the requested vehicle downshift deceleration when the vehicle is decelerating or if the foot brake is activated.

[0008] The above several kinds of dynamically regulated accelerations are selected and output as the final requested acceleration. When no shuttle signal is detected, i.e., the driving direction has not changed, the maximum value of the vehicle downshift deceleration controlled when the vehicle is decelerating or if the foot brake is activated and the vehicle acceleration requested through the transmission ratio difference is taken as the final requested acceleration. When the driving direction changes, i.e., the shuttle signal is detected, the maximum value of the vehicle downshift deceleration controlled during the change in driving direction and the vehicle downshift deceleration controlled when the vehicle is decelerating or if the foot brake is activated is taken as the final requested acceleration when the brake signal is detected. When the driving direction changes but the brake signal is not detected, the vehicle downshift deceleration controlled during the change in driving direction is taken as the final requested acceleration.

[0009] Further, the adjustment process of the requested vehicle acceleration through the transmission ratio difference control is that: the difference between the absolute value of the expected transmission ratio and the absolute value of the actual transmission ratio is looked up to obtain the corresponding requested acceleration, and the transmission ratio deviation is controlled to be 0 by adjusting the gear position.

[0010] Further, the difference between the absolute value of the expected transmission ratio and the absolute value of the actual transmission ratio is looked up to obtain the corresponding requested acceleration, and the dynamic saturation threshold is limited.

[0011] Further, in the PTO mode, the upper limit threshold of the requested vehicle acceleration is jointly limited by three functions, and the minimum value of the output values of the three functions is taken as the final upper limit threshold; when not in the PTO mode, the upper limit threshold of the requested vehicle acceleration is jointly limited by two functions, and the minimum value of the output values of the two functions is taken as the final upper limit threshold.

[0012] Further, the three functions in the PTO mode are: a function about the maximum transmission output torque and the vehicle weight, a function about the vehicle reversing operation lever position, and a one-dimensional linear difference function about the PTO expected engine speed set point; the two functions not in the PTO mode are: a function about the maximum transmission output torque and the vehicle weight, and a one-dimensional linear difference function about the actual vehicle speed.

[0013] Further, during the change of the driving direction, the adjustment process of the requested vehicle downshift deceleration is controlled as follows: the reversing lever position is looked up to obtain the corresponding requested acceleration, and the final requested acceleration is obtained by multiplying the vehicle acceleration coefficient.

[0014] Further, the vehicle acceleration coefficient is jointly limited by three functions, and the minimum value of the three functions is taken as the acceleration coefficient, wherein function one is a constant function set to 1 at all vehicle speeds; function two is a one-dimensional linear difference function about the minimum value of the actual vehicle speed and the expected vehicle speed when the reversing shuttle signal is 1, and a one-dimensional linear difference function about the expected vehicle speed when the shuttle signal is 0; function three is that if the expected vehicle speed is zero, the upshift is stopped at the zero crossing point of the requested transmission ratio, that is, the acceleration coefficient is 0, otherwise the acceleration coefficient is 1.

[0015] Further, when the vehicle is decelerating or if the foot brake is activated, the adjustment process of the requested vehicle downshift deceleration is controlled as follows: there are four cases, which are: normal downshift without using the brake when the hand throttle is not activated; downshift using the brake when the hand throttle is not activated; normal downshift without using the brake when the hand throttle is activated; downshift using the brake when the hand throttle is activated.

[0016] Further, when the hand throttle is not activated and normal downshift is not performed using the brake, the vehicle deceleration is a one-dimensional linear difference function with respect to the actual vehicle speed, at this time, the vehicle deceleration is simultaneously limited by a dynamic saturation threshold, the upper limit is a constant 0.

[0017] Further, when the hand throttle is not activated and normal downshift is not performed using the brake, the vehicle deceleration is a one-dimensional linear difference function with respect to the actual vehicle speed, at this time, the vehicle deceleration is simultaneously limited by a dynamic saturation threshold, the upper limit is a constant 0.

[0018] Compared with the prior art, the present application has the following beneficial technical effects:

[0019] The large-horsepower tractor acceleration dynamic adjustment method of the present application dynamically adjusts the requested acceleration for various driving states of the vehicle, respectively designs the vehicle acceleration logic controlled by the transmission ratio difference request, designs the vehicle downshift deceleration logic controlled by the request during the driving direction change, designs the vehicle downshift deceleration logic controlled by the request when the vehicle is decelerating or if the foot brake is activated, finally matches the appropriate vehicle requested acceleration, and limits the vehicle requested acceleration threshold in each state. This method greatly improves the vehicle stability during driving, reduces the impact effect caused by gear shifting, and improves the driving experience of the driver. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The large-horsepower tractor acceleration dynamic adjustment method control logic diagram in the embodiments of the present application. DETAILED DESCRIPTION

[0021] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should be within the scope of protection of the present application.

[0022] The large-horsepower tractor acceleration dynamic adjustment method of the present application includes the following three driving state acceleration dynamic adjustment: vehicle acceleration controlled by the transmission ratio difference request; vehicle downshift deceleration controlled by the request during the driving direction change; vehicle downshift deceleration controlled by the request when the vehicle is decelerating or if the foot brake is activated.

[0023] As Figure 1As shown, the final requested acceleration is the output of the above several dynamic adjustments of the acceleration selection, specifically, when no shuttle signal is detected, i.e. the driving direction has not changed, the maximum value of the vehicle downshift deceleration control request and the vehicle acceleration control request when the vehicle is decelerating or if the foot brake is activated is taken as the final requested acceleration; when the driving direction changes, i.e. the shuttle signal is detected, when the brake signal is detected, the maximum value of the vehicle downshift deceleration control request during the driving direction change and the vehicle downshift deceleration control request when the vehicle is decelerating or if the foot brake is activated is taken as the final requested acceleration; when the driving direction changes but no brake signal is detected, the vehicle downshift deceleration control request during the driving direction change is taken as the final requested acceleration.

[0024] Specifically, the logic design of the vehicle acceleration control requested by the transmission ratio difference value is as follows:

[0025] The difference between the input expected transmission ratio absolute value (where the forward gear transmission ratio value is negative and the reverse gear transmission ratio value is positive) and the actual transmission ratio absolute value is looked up in a table, which is shown in Table 1 of the one-dimensional linear difference function of the transmission ratio control:

[0026] Table 1

[0027]

[0028] If the transmission ratio difference value is greater than 0, the requested acceleration is greater than 0, at which time the gearbox is upshifted until the control transmission ratio deviation gradually becomes 0; similarly, if the transmission ratio difference value is less than 0, the requested acceleration is less than 0, and the gearbox is downshifted until the control transmission ratio deviation is 0, and in the process of the transmission ratio difference value gradually becoming zero, the vehicle requested acceleration gradually changes until it is 0.

[0029] The requested acceleration output after the table lookup is dynamically saturated and limited in the upper and lower ranges, where the determination of the dynamic saturation threshold is divided into two cases: in the PTO mode and not in the PTO mode.

[0030] Specifically, in the PTO mode, the upper limit threshold of the requested vehicle acceleration is limited by three functions, and the minimum value of the output values of the three functions is taken as the final upper limit threshold, the three functions are the function of the requested acceleration with respect to the maximum gearbox output torque and the vehicle weight, the function of the requested acceleration with respect to the vehicle reversing lever position, and the one-dimensional linear difference function of the requested acceleration with respect to the PTO expected engine speed set point.

[0031] Function 1: Function with respect to maximum gearbox output torque and vehicle weight;

[0032] The requested acceleration is equal to the planetary carrier maximum output torque multiplied by the transmission ratio, divided by the tire radius and the vehicle gross weight, the resulting requested acceleration is saturated with a threshold limit, the lower limit is -0.5 m / s2, the upper limit is 5 m / s2.

[0033] Function two: a function of the vehicle reversing lever position, as shown in Table 2

[0034] Table 2

[0035]

[0036] Function three: a one-dimensional linear interpolation function of the PTO desired engine speed setpoint, as shown in Table 3;

[0037] Table 3

[0038]

[0039] When not in PTO mode, the requested vehicle acceleration upper threshold limit is jointly limited by two functions, a function of the maximum gearbox output torque and the vehicle weight and a one-dimensional linear interpolation function of the actual vehicle speed.

[0040] Function one: a function of the maximum gearbox output torque and the vehicle weight, the same as function one in PTO mode, the requested acceleration is equal to the planetary carrier maximum output torque multiplied by the transmission ratio, divided by the tire radius and the vehicle gross weight.

[0041] Function two: a one-dimensional linear interpolation function of the actual vehicle speed, as shown in Table 4;

[0042]

[0043] In both modes, the lower threshold limit of the requested acceleration dynamic saturation threshold is a constant -2.5 m / s2.

[0044] In particular, when the desired transmission ratio is equal to zero and the vehicle speed is less than 50 km / h, the requested acceleration of the transmission ratio control is the minimum value of the output requested acceleration after dynamic saturation threshold limiting and the requested acceleration after function lookup of the reversing lever position, otherwise, the requested acceleration of the transmission ratio control is the output requested acceleration after dynamic saturation threshold limiting.

[0045] Wherein, the function of the reversing lever position is shown in Table 5;

[0046] Table 5

[0047]

[0048] In addition, to ensure vehicle safety, when a braking signal is detected and the vehicle speed is greater than 0.5 km / h, the maximum expected vehicle deceleration is fixed at -5 m / s^2 for rapid downshifting.

[0049] Specifically, during a change of driving direction (reversing direction), the logic design for controlling the vehicle's downshifting and deceleration is as follows:

[0050] The required acceleration is obtained by looking up the table for the position of the directional lever. The obtained required acceleration is multiplied by the vehicle acceleration coefficient to obtain the final required acceleration. The directional lever function is shown in Table 6.

[0051] Table 6

[0052]

[0053] The vehicle acceleration coefficient is constrained by three functions, and the minimum value of the three functions is taken as the acceleration coefficient.

[0054] Function 1 is a constant function that is set to 1 at all vehicle speeds;

[0055] Function 2 is a one-dimensional linear difference function with respect to vehicle speed. By performing edge detection on the shuttle signal, it is set to 1 when the shuttle signal is detected. Since this tractor can achieve power reversal without stopping, the minimum value between the actual vehicle speed and the expected vehicle speed is taken (the expected vehicle speed is not equal to 0, that is, when the accelerator pedal is pressed, the expected vehicle speed at this time is the maximum speed of reverse driving). Then, this value is used to look up the vehicle acceleration for shuttle start, and this value is kept constant during the forward deceleration period, no longer changing with the decrease of vehicle speed. When the actual vehicle speed drops to 0, the reversing shuttle signal is set to 0, and then the expected vehicle speed is directly taken to look up the vehicle acceleration for shuttle start, and this value is kept constant during the reverse acceleration period, no longer changing with the increase of vehicle speed.

[0056] The one-dimensional linear difference function for actual or desired vehicle speed is shown in Table 7. It should be noted that when looking up the table, both actual and desired vehicle speeds are queried using Table 7.

[0057] Table 7

[0058] Vehicle speed (km / h) 0 1 2 5 Acceleration coefficient 0.300 0.300 0.600 1.000

[0059] Function 3 stops upshifting at the point where the requested gear ratio crosses zero if the desired vehicle speed is zero, i.e., the acceleration coefficient is 0; otherwise, the acceleration coefficient is 1.

[0060] To ensure a smooth transition from acceleration to deceleration during the final shuttle period, this invention controls the acceleration rate by increasing the filter constant from 0.0005 to 1. In other words, the final output acceleration requested during the shuttle period is gradually increased from 0 to the target value.

[0061] Similarly, in this state, to ensure vehicle safety, when a braking signal is detected and the vehicle speed is greater than 0.5 km / h, the maximum expected vehicle deceleration of -5 m / s^2 is fixed and a rapid downshift is performed.

[0062] Specifically, the logic design for controlling the vehicle's downshifting deceleration when the vehicle decelerates or if the foot brake is activated is as follows:

[0063] It includes four situations: downshifting normally without using the brake when the hand throttle is not activated; downshifting with the brake when the hand throttle is not activated; downshifting normally without using the brake when the hand throttle is activated; and downshifting with the brake when the hand throttle is activated.

[0064] Scenario 1: When the hand throttle is not activated, normal downshifting is performed without using the brakes;

[0065] When downshifting normally without using the brakes and without manually throttle engaged, the maximum permissible vehicle deceleration is set as a one-dimensional linear difference function of the actual vehicle speed, as shown in Table 8:

[0066] Table 8

[0067]

[0068] The maximum vehicle deceleration set above is also limited by a dynamic saturation threshold, with an upper limit of a fixed value of 0 and a lower limit of the value obtained by looking up the reversing lever position function, as shown in Table 9:

[0069] Table 9

[0070]

[0071] Scenario 2 involves downshifting using the brakes when the hand throttle is not activated;

[0072] When the hand throttle is not activated and a braking signal is detected, the maximum allowable vehicle deceleration is set as a two-dimensional linear difference function of the actual engine speed minus the expected engine speed and the actual vehicle speed, as shown in Table 10.

[0073] Table 10

[0074]

[0075] Scenario 3 is when the hand throttle is activated, and the brake is not used for normal downshifting;

[0076] In manual throttle mode, when a braking signal is detected, the maximum allowable vehicle deceleration is set as a two-dimensional linear difference function of the actual engine speed minus the desired engine speed and the actual vehicle speed, as shown in Table 11.

[0077] Table 11

[0078]

[0079] Scenario 4 involves using the brake to downshift when the hand throttle is activated;

[0080] In manual throttle mode, when no braking signal is detected, the maximum allowable vehicle deceleration is set as a two-dimensional linear difference function of the actual engine speed minus the desired engine speed and the actual vehicle speed, as shown in Table 12.

[0081] Table 12

[0082]

[0083] In summary, this invention selects and outputs the above-mentioned dynamically adjusted accelerations as the final requested acceleration. Specifically, the control logic is as follows: when no shuttle signal is detected, the maximum value of the vehicle downshift deceleration requested during vehicle deceleration or if the foot brake is activated, and the vehicle acceleration requested by the gear ratio difference, is taken as the final requested acceleration. When the driver wants to change the driving direction, i.e., a shuttle signal is detected, the system further determines whether there is a braking signal. If a braking signal is detected, the maximum value of the vehicle downshift deceleration requested during the change of driving direction and the vehicle downshift deceleration requested during vehicle deceleration or if the foot brake is activated, is taken as the final requested acceleration. When the driver wants to change the driving direction, i.e., a shuttle signal is detected, but no braking signal is detected, the vehicle downshift deceleration requested during the change of driving direction is taken as the final requested acceleration.

Claims

1. A method for dynamically adjusting the acceleration of a high-horsepower tractor, characterized in that, Includes the following processes: Control the requested vehicle acceleration by the gear ratio difference; control the requested vehicle downshift deceleration during a change of driving direction; control the requested vehicle downshift deceleration when the vehicle is decelerating or if the foot brake is activated. The system will control the requested vehicle acceleration via the gear ratio difference; control the requested vehicle downshift deceleration during a change in driving direction; and control the requested vehicle downshift deceleration as the final requested acceleration when the vehicle decelerates or, if the foot brake is activated. When no shuttle signal is detected, i.e., the driving direction has not changed, the maximum value of the requested vehicle downshift deceleration during deceleration or, if the foot brake is activated, and the requested vehicle acceleration via the gear ratio difference will be taken as the final requested acceleration. When the driving direction changes, i.e., when a shuttle signal is detected, or when a braking signal is detected, the maximum value of the requested vehicle downshift deceleration during the change in driving direction and the requested vehicle downshift deceleration during deceleration or, if the foot brake is activated, will be taken as the final requested acceleration. When the driving direction changes but no braking signal is detected, the vehicle downshift deceleration requested during the change of driving direction is taken as the final requested acceleration.

2. The method for dynamic acceleration adjustment of a high-horsepower tractor according to claim 1, characterized in that, The dynamic adjustment process of vehicle acceleration requested by controlling the transmission ratio difference is as follows: the difference between the absolute value of the desired transmission ratio and the absolute value of the actual transmission ratio is looked up in a table to obtain the corresponding requested acceleration, and the transmission controls the transmission ratio difference to be 0 by adjusting the gear.

3. The method for dynamic acceleration adjustment of a high-horsepower tractor according to claim 2, characterized in that, The difference between the absolute value of the desired transmission ratio and the absolute value of the actual transmission ratio is used to look up the corresponding requested acceleration and then apply a dynamic saturation threshold limit.

4. The method for dynamic acceleration adjustment of a high-horsepower tractor according to claim 3, characterized in that, In PTO mode, the requested upper limit threshold for vehicle acceleration is constrained by three functions, and the final upper limit threshold is obtained by taking the minimum value of the output of the three functions. When not in PTO mode, the requested upper limit threshold for vehicle acceleration is limited by two functions, and the final upper limit threshold is obtained by taking the minimum value of the output values ​​of the two functions.

5. The method for dynamic acceleration adjustment of a high-horsepower tractor according to claim 4, characterized in that, The three functions in PTO mode are: a function relating to the maximum transmission output torque and vehicle weight, a function relating to the position of the vehicle's steering lever, and a one-dimensional linear difference function relating to the engine speed setpoint expected in PTO. The two functions outside of PTO mode are: a function relating to the maximum transmission output torque and vehicle weight, and a one-dimensional linear difference function relating to the actual vehicle speed.

6. The method for dynamic acceleration adjustment of a high-horsepower tractor according to claim 1, characterized in that, During a change in driving direction, the dynamic adjustment process of the vehicle downshift deceleration requested by the control is as follows: the corresponding requested acceleration is obtained by looking up the position of the steering lever in a table, and the obtained requested acceleration is multiplied by the vehicle acceleration coefficient to obtain the final requested acceleration.

7. The method for dynamic acceleration adjustment of a high-horsepower tractor according to claim 6, characterized in that, The vehicle acceleration coefficient is constrained by three functions, and the minimum value of the three functions is taken as the vehicle acceleration coefficient. Function 1 is a constant function that is set to 1 at all vehicle speeds; Function 2 is a one-dimensional linear difference function of the minimum value of the actual vehicle speed and the desired vehicle speed when the reversing shuttle signal is set to 1, and a one-dimensional linear difference function of the desired vehicle speed when the shuttle signal is set to 0; Function 3 stops upshifting at the zero point of the requested transmission ratio if the desired vehicle speed is zero, that is, the vehicle acceleration coefficient is 0, otherwise the vehicle acceleration coefficient is 1.

8. The method for dynamic acceleration adjustment of a high-horsepower tractor according to claim 1, characterized in that, When the vehicle decelerates or if the foot brake is activated, the dynamic adjustment process of the vehicle downshift deceleration requested by the control includes four situations: when the hand throttle is not activated, normal downshifting is performed without using the brakes; When the hand throttle is not activated, use the brake to downshift; When the hand throttle is activated, downshifting should be performed without using the brakes; When the hand throttle is activated, use the brake to downshift.

9. The method for dynamic acceleration adjustment of a high-horsepower tractor according to claim 8, characterized in that, When the hand throttle is not activated and the brake is not used for normal downshifting, the vehicle's downshift deceleration is a one-dimensional linear difference function of the actual vehicle speed. At this time, the vehicle's downshift deceleration is also limited by a dynamic saturation threshold, with an upper limit of 0.

10. The method for dynamic acceleration adjustment of a high-horsepower tractor according to claim 8, characterized in that, When the hand throttle is not activated and the brake is used for normal downshifting; when the hand throttle is activated and the brake is not used for normal downshifting; when the hand throttle is activated and the brake is used for normal downshifting; The deceleration of a vehicle when downshifting is a two-dimensional linear difference function of the actual engine speed minus the expected engine speed and the actual vehicle speed.

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