An AMT heavy-duty truck starting control method and system

Abstract

The present invention discloses a starting control method and system for an AMT heavy-duty truck, which sets the target engine speed and the target clutch speed; determines the speed difference according to the target clutch speed and the actual engine speed; respectively determines the FF basic torque and the PI torque based on the speed difference; determines the target clutch torque according to the FF basic torque and the PI partial torque, and controls the target clutch displacement according to the target clutch torque until the engine speed and the input shaft speed are synchronized to achieve starting control. The present invention can adjust the engagement and separation of the clutch and their rates in real time according to the driver's throttle operation and the engine speed fluctuation during the starting process, which can not only ensure the starting smoothness but also meet the driver's demand for rapid starting.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle control, and particularly relates to a starting control method and system for an AMT heavy-duty truck. Background Technique

[0002] Compared with the traditional manual transmission (MT), the automated mechanical transmission (AMT) has the advantages of simple operation, intelligent shifting, and taking into account both power and fuel consumption. Compared with the automatic transmission (AT), it has the advantages of strong power, high transmission efficiency, fuel saving, low price, and low maintenance cost. It has become the main development direction of future commercial vehicle transmissions and is also an effective way to solve problems such as fuel consumption of commercial vehicles, component wear reduction, and driving safety improvement. Due to the complex external driving environment of commercial vehicles, diverse subjective intentions of drivers, and the fact that the vehicle is a time-varying, non-linear system with multiple inputs and outputs and many external interference factors, the development difficulty of AMT control strategies has increased. Among them, the starting control strategy is one of the core technologies and also one of the difficulties. Starting control needs to consider both starting smoothness and starting speed. In addition, clutch slip friction will occur during the starting process. While the vehicle starts smoothly, it is also necessary to prevent the clutch from reducing its service life due to excessive wear and high temperature.

[0003] An existing starting control method for AMT vehicles determines the target engagement position of the clutch according to the change, magnitude of the accelerator pedal, and engine speed, and makes corresponding modifications to the target position of the clutch according to the change in jerk to ensure that the target engagement rate is controlled in different regions during the clutch engagement stroke, and the target engagement rate is corrected. Step 1: Before starting, confirm the slip friction interval of the vehicle according to the first operation of the clutch; Step 2: Analyze the accelerator pedal from the slip friction interval to determine whether the driver has an acceleration request; Step 3: When an acceleration request is detected, determine the target engagement position of the clutch according to the change, magnitude of the accelerator pedal, and engine speed, and establish a one-dimensional table of jerk and clutch change; Step 4: Make corresponding modifications to the target position of the clutch according to the change in jerk to ensure that the target engagement rate is controlled in different regions during the clutch engagement stroke; Step 5: Correct the target engagement rate according to the rotational speed difference between the driving shaft and the driven shaft of the clutch, the accelerator pedal, and the engine speed. In principle, this method can improve the smoothness of starting control, but during the discrete difference calculation of jerk in the control, the error is large and the signal is easily mixed with noise. If not handled well, it will instead affect the smoothness of starting, and the implementation difficulty is relatively large.

[0004] Another existing starting control method for AMT vehicles adopts the following steps: a. Start the engine, engage the starting gear, and the electronically controlled mechanical automatic transmission (AMT) controls the engine to maintain an idle state, and gently step on the accelerator to send a starting signal; b. After receiving the starting signal, control the power source to drive the clutch to the semi-engaged point; c. The AMT controls the engine speed to be 650 - 1300 rpm, and detects whether the output shaft speed is greater than 50 rpm; d. The AMT controls the engine torque limit to gradually increase from 40% to 100%, and at the same time controls the power source to drive the clutch to gradually engage, detects whether the clutch slip rate is less than 5%, and whether the output shaft speed is greater than 120 rpm; e. The AMT stops controlling the engine, and the vehicle starting process ends. However, the working condition adaptability of this control method is poor, the power loss is large when the driver accelerates suddenly or starts on a slope, and there are few dynamic corrections of the control process parameters, making it difficult to well follow the driver's active pedal demand. Summary of the Invention

[0005] The purpose of the present invention is to solve the deficiencies existing in the above background technology and provide a starting control method and system for an AMT heavy-duty truck.

[0006] The technical solution adopted by the present invention is: a starting control method for an AMT heavy-duty truck, setting the engine target speed and the clutch target speed;

[0007] Determine the speed difference according to the clutch target speed and the actual engine speed;

[0008] Based on the speed difference, respectively determine the FF base torque and the PI torque;

[0009] Determine the clutch target torque according to the FF base torque and the PI partial torque, and control the clutch target displacement according to the clutch target torque to achieve starting control

[0010] Further, after setting the engine target speed, determine the engine speed slope according to the vehicle load, slope, and atmospheric pressure parameters to control the starting smoothness of the engine speed.

[0011] Further, when the engine has smoke limit, limit the clutch engagement rate and increase the engine target speed.

[0012] Further, the clutch target speed is determined by throttle, air pressure, slope, and vehicle mass parameters.

[0013] Further, after setting the clutch target speed, determine the clutch speed slope according to the throttle opening to make the clutch target speed change smoothly.

[0014] Further, the FF base torque is obtained by looking up a table according to the rotational speed difference and the throttle opening.

[0015] Further, the clutch target torque is the sum of the FF base torque and the PI part torque.

[0016] Furthermore, after determining the clutch target torque, slope limiting is performed on the clutch target torque, and then the clutch target displacement is determined by looking up a table according to the clutch torque transmission characteristic parameters.

[0017] An AMT heavy-duty truck starting control method includes

[0018] An engine control module for controlling the engine speed according to the set engine target speed;

[0019] A rotational speed difference module for determining the rotational speed difference according to the clutch target speed and the actual engine speed;

[0020] An FF module for determining the FF base torque according to the rotational speed difference;

[0021] A PI module for performing PI control according to the rotational speed difference to determine the PI part torque;

[0022] A clutch target torque module for determining the clutch target torque according to the FF base torque and the PI part torque;

[0023] A torque slope limiting module for performing slope limiting on the clutch target torque;

[0024] A torque-to-displacement module for converting the clutch target torque into the clutch target displacement by looking up a table according to the clutch torque transmission characteristic parameters.

[0025] Further, the clutch target torque is the sum of the FF base torque and the PI part torque.

[0026] The beneficial effects of the present invention are as follows: In the starting stage of the present invention, the engine and the clutch are controlled. The clutch control adopts a control method based on FF+PI. This control method can adjust the engagement and separation of the clutch and its rate in real time according to the driver's throttle operation and the engine speed fluctuation during the starting process, which can not only ensure the starting smoothness but also meet the driver's rapid starting requirement. Description of the Drawings

[0027] Figure 1 is the schematic diagram of the starting control of the present invention.

[0028] Figure 2 is the schematic diagram of the clutch control of the present invention. Detailed Embodiments

[0029] The following further describes the specific embodiments of the present invention in conjunction with the accompanying drawings. It should be noted here that the description of these embodiments is used to help understand the present invention, but does not limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] In the case of using "including", "having", and "containing" described in this specification, unless otherwise used, it may also have another part or other parts, and the terms used can generally be singular but can also represent plural forms.

[0031] In addition, when constructing components, although there is no explicit description thereof, it can be understood that there must be a certain error range.

[0032] The features of the various embodiments of the present invention can be partially or fully combined or spliced with each other, and can be implemented in various different configurations as can be fully understood by those skilled in the art. The embodiments of the present invention can be implemented independently of each other, or can be implemented together in a mutually dependent relationship.

[0033] As Figure 1 shown, the present invention provides a starting control method for an AMT heavy-duty truck that comprehensively considers vehicle operating conditions and driver requirements, which involves engine control and clutch control, and the clutch control adopts a control method based on FF+PI.

[0034] 1. Engine control.

[0035] During the starting stage, the engine speed is controlled. A target engine speed is given, and the calculation of the target engine speed size adopts multi-parameter calculation. First, the throttle input reflects the driver's demand, so the throttle parameter is used as the main control parameter for calculating the target speed. The engine speed has a great impact on the starting smoothness, starting speed, and starting ability. The higher the engine speed, the more unfavorable it is for clutch slip friction, and the greater the impact on the clutch life. Therefore, it is necessary to set the weights of the corresponding parameters according to parameters such as vehicle load, slope, and atmospheric pressure, and adjust the target engine speed.

[0036] When the engine reaches the smoke limit, the torque capacity drops severely, which will affect the starting, especially the starting on a slope with a large resistance. In severe cases, the starting fails due to insufficient engine torque. Therefore, when the engine reaches the smoke limit, the target engine speed should be increased to avoid the engine speed being dragged down by lifting the engine speed.

[0037] 2. Clutch control

[0038] During the starting stage, the clutch control adopts a control method based on FF+PI, and the basic principle is as Figure 2 shown.

[0039] 2.1. Set the target speed of the clutch:

[0040] Based on the engine idle speed, make addition corrections according to the throttle, air pressure, ramp, and mass to determine the target speed of the clutch. To make the target speed change smoothly, perform slope control on the clutch requested speed. The slope size is affected by the throttle opening. The larger the throttle, the larger the slope.

[0041] 2.2. Calculate the speed difference

[0042] Calculate the difference between the target speed of the clutch after slope limitation and the current actual engine speed as the speed difference. This speed difference is the basis for setting the torque by FF+PI control.

[0043] 2.3. Calculate the FF basic torque

[0044] The size of the FF basic torque value determines the starting response speed and starting smoothness at the initial stage of starting. Look up the table according to the speed difference and throttle size to obtain the size of the FF basic torque. The smaller the speed difference and the larger the throttle, the larger the basic torque. Considering the influence of the external environment, correct the FF basic torque value according to the atmospheric pressure, load, and ramp. When the air pressure is lower than 7 bar, the basic torque is reduced by 10%; when the air pressure is lower than 6 bar, the FF basic torque is reduced by 20%; when the load is large and the ramp is large, the FF basic torque is increased by 1-2.5 times. When reversing, higher requirements are placed on smoothness and reversing accuracy, so the basic torque during reversing is appropriately reduced.

[0045] After setting the FF basic torque value, set the change slope of the FF basic torque according to the throttle size. The larger the throttle, the larger the slope. The basic slope is the calibrated value, about 100 NM / S. As the throttle increases, the slope is multiplied by a correction factor of 1-5, that is, the slope increases by 1-5 times. The FF basic torque slope also needs to consider the load and ramp conditions. When the load is large and the ramp is large, the basic torque slope is increased by 1-2 times.

[0046] In addition, the basic torque slope also needs to consider the low adhesion situation. On a low adhesion and slippery road surface, it is necessary to reduce the clutch engagement rate, that is, make a reduction correction to the basic torque slope.

[0047] 2.4. Calculate the PI part torque

[0048] Use PI control to determine the PI part torque. P is the proportional torque and I is the integral torque. The P and I coefficients gradually increase with the increase of the starting time to enhance the influence of PI. According to the throttle size, adjust the size of the I coefficient. Without impact, the larger the I coefficient, the better.

[0049] 2.5. Clutch target torque determination. Apply to the clutch and wait for the engine speed and input value speed to change until they are synchronized.

[0050] The clutch target torque is the sum of the FF base torque and the PI part torque. After determining the clutch target torque, perform slope limitation on the clutch target torque. At the same time, determine the clutch target displacement by looking up the table according to the clutch torque transmission characteristic parameters, and control the clutch until the engine speed and the input shaft speed are synchronized, so as to achieve the starting control of the AMT heavy-duty truck. The clutch torque transmission characteristic parameters are affected by temperature and wear degree.

[0051] When the engine has a smoke limit, limit the clutch engagement rate to within 500 Nm / , to avoid the engine speed being dragged down due to too fast clutch engagement, and at the same time increase the engine target speed to 1.5 - 3 times the original set target speed. Through the control of high engine speed and slow clutch engagement, sacrifice the clutch slip time to ensure a successful start.

[0052] It should be understood that the specific order or hierarchy of steps in the disclosed process is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of the present disclosure. The appended method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0053] The above description includes examples of one or more embodiments. Of course, it is impossible to describe all possible combinations of components or methods for the purpose of describing the above embodiments, but those of ordinary skill in the art should recognize that the various embodiments can be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications, and variations that fall within the scope of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, the manner in which this term is encompassed is similar to the term "including" as interpreted when "including" is used as a transitional word in a claim. In addition, any use of the term "or" in the specification or claims of the present application is intended to mean "non-exclusive or".

[0054] Those skilled in the art can also understand that the various illustrative logical blocks, units, and steps listed in the embodiments of the present invention can be implemented by electronic hardware, computer software, or a combination of both. To clearly show the interchangeability of hardware and software, the above-mentioned various illustrative components, units, and steps have been generally described in terms of their functions. Whether such functions are implemented by hardware or software depends on the specific application and the design requirements of the entire system. Those skilled in the art can use various methods to implement the described functions for each specific application, but such implementation should not be construed as exceeding the scope of protection of the embodiments of the present invention.

[0055] In the embodiments of the present invention, the various illustrative logical blocks or units can be implemented or operated to perform the described functions by a general-purpose processor, a digital signal processor, an application-specific integrated circuit (ASIC), a field-programmable gate array, or other programmable logic devices, discrete gate or transistor logic, discrete hardware components, or any combination of the above designs. The general-purpose processor can be a microprocessor. Optionally, the general-purpose processor can also be any conventional processor, controller, microcontroller, or state machine. The processor can also be implemented by a combination of computing devices, such as a digital signal processor and a microprocessor, multiple microprocessors, one or more microprocessors combined with a digital signal processor core, or any other similar configuration.

[0056] The above is only the preferred embodiment of the present invention and the technical principles applied. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein. Various obvious changes, re-adjustments, combinations with each other, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments. Without departing from the concept of the present invention, more other equivalent embodiments can be included, and the scope of the present invention is determined by the scope of the appended claims. The content not described in detail in this specification belongs to the prior art well-known to those skilled in the art.

Claims

1. A starting control method for an AMT heavy-duty truck, characterized in that: Set the target engine speed and the target clutch speed; Determine the speed difference according to the target clutch speed and the actual engine speed; Based on the speed difference, determine the FF basic torque and the PI part torque respectively, and correct the FF basic torque according to the atmospheric pressure, load and slope; Determine the target clutch torque according to the FF basic torque and the PI part torque, the target clutch torque is the sum of the FF basic torque and the PI part torque, and control the target clutch displacement according to the target clutch torque until the engine speed and the input shaft speed are synchronized to achieve starting control.

2. The starting control method of the AMT heavy-duty truck according to claim 1, characterized in that: After setting the target engine speed, determine the engine speed slope according to the vehicle load, slope and atmospheric pressure parameters to control the starting smoothness of the engine speed.

3. The AMT heavy-duty truck starting control method according to claim 1, wherein: When the engine has smoke limit, limit the clutch engagement rate and increase the target engine speed.

4. The starting control method of the AMT heavy-duty truck according to claim 1, characterized in that: The target clutch speed is determined by throttle, air pressure, slope and vehicle mass parameters.

5. The starting control method for an AMT heavy-duty truck according to claim 1, characterized in that: After setting the target clutch speed, determine the speed slope of the clutch according to the throttle opening to make the target clutch speed change smoothly.

6. The starting control method for an AMT heavy-duty truck according to claim 1, characterized in that: The FF basic torque is obtained by looking up a table according to the speed difference and the throttle size.

7. The starting control method of the AMT heavy-duty truck according to claim 1, wherein: After determining the target clutch torque, perform slope limitation on the target clutch torque, and then determine the target clutch displacement by looking up a table according to the clutch torque transmission characteristic parameters.

8. An AMT heavy-duty truck starting control system, characterized in that: Including An engine control module for controlling the engine speed according to the set target engine speed; A speed difference module for determining the speed difference according to the target clutch speed and the actual engine speed; An FF module for determining the FF basic torque according to the speed difference and correcting the FF basic torque according to the atmospheric pressure, load and slope; A PI module for performing PI control according to the speed difference to determine the PI part torque; A target clutch torque module for determining the target clutch torque according to the FF basic torque and the PI part torque; the target clutch torque is the sum of the FF basic torque and the PI part torque; A torque slope limitation module for performing slope limitation on the target clutch torque; A torque-to-displacement module for converting the target clutch torque into the target clutch displacement by looking up a table according to the clutch torque transmission characteristic parameters.

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