Torque Control Method and System for Vehicle Engine

Abstract

The present invention provides a torque control method and system for a vehicle engine. The method includes: obtaining the position of the vehicle's accelerator pedal; when the accelerator pedal of the vehicle is released, controlling the clutch to open at a preset first rate and controlling the torque of the engine to drop to a first torque threshold. Moreover, continuously detecting and obtaining the real-time speed of the engine, and when the real-time speed of the engine drops to a preset first speed threshold, controlling the torque of the engine to rise according to the real-time speed of the engine. During the process of the torque of the engine rising, continuously detecting and obtaining the real-time pressure of the clutch, and comparing to obtain the difference between the real-time pressure of the clutch and the target pressure of the clutch; when the difference is less than a preset pressure threshold, controlling the torque of the engine to drop to a preset second torque threshold at a preset second rate. Thus, by controlling the torque of the engine, it is ensured that the deceleration does not suddenly decrease after releasing the accelerator, the deceleration is smoother, and the driving experience is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of dual-clutch automatic transmissions, and particularly to a torque control method and system for a vehicle engine. Background Art

[0002] During the control process of a dual clutch, when the vehicle speed is relatively low, in order to prevent the engine speed from dropping or stalling, or to prevent the vehicle from shaking caused by engine torque fluctuations, the clutch will be in a slip control mode. In the low-speed driving condition, the driver needs to continuously release and press the accelerator pedal to control the vehicle speed. When the driver presses the accelerator pedal, the engine is at a relatively low speed, and at this time, the torque of the engine is insufficient. Therefore, the clutch adopts slip control, that is, enters the starting control. First, the engine speed is increased to a certain target, and then the clutch is engaged to synchronize the current clutch speed with the engine speed. Before the clutch is synchronized, the driver will immediately release the accelerator pedal. At this moment, in order to respond to the driver's demand, the clutch will open at a certain rate. However, due to the mismatch between the engine filter and the opening rate of the Transmission Control Unit (TCU), the engine torque drops too fast, which will cause the engine speed to drop and generate a shaft impact. If the engine filter is too slow, after the clutch opens, the engine speed will soar. Since the clutch and the engine are in a slip friction separation state, after the accelerator pedal is released, the engine returns to the idle control, and the engine speed will drop. If this process is not well controlled, it is easy to generate jerks and noises.

[0003] In the actual control process, when the driver completely releases the accelerator pedal, the engine enters the idle control. Currently, the idle control of the engine only considers the proportional and integral parts in the PID algorithm, lacking the differential part. Therefore, in the actual vehicle performance, as Figure 1 shown, during the process of the engine speed soaring and then dropping, the engine speed is likely to be lower than the clutch speed. At this moment, the clutch has a certain load, which is likely to generate shaft-piercing noises. Then, the clutch increases the clutch torque through closed-loop control to eliminate the speed difference. This process will cause a sudden change in the vehicle deceleration and uneven deceleration, affecting the driving comfort.

[0004] Therefore, in the low-speed driving condition, the driver needs to continuously release and press the accelerator pedal to control the vehicle speed. After the driver releases the accelerator pedal, during the process of the engine returning from a high speed to the clutch speed, the engine speed is likely to be lower than the clutch speed. At this time, the clutch has a certain load, which is likely to generate noises. Then, the clutch needs to increase the clutch torque through closed-loop control to eliminate the speed difference. This process is likely to cause a sudden change in the vehicle deceleration and uneven deceleration, affecting the driving comfort. Summary of the Invention

[0005] The object of the present invention is to solve the problems in the prior art that after the vehicle releases the accelerator pedal, the engine speed will be lower than the clutch speed, resulting in noise, sudden change in deceleration, and uneven deceleration.

[0006] To solve the above problems, an embodiment of the present invention discloses a torque control method for a vehicle engine, including the following steps:

[0007] S1: Obtain the position of the vehicle's accelerator pedal, and determine whether the vehicle's accelerator pedal is released according to the position of the vehicle's accelerator pedal; if so, execute step S2; if not, continue to determine whether the vehicle's accelerator pedal is released;

[0008] S2: Control the clutch to open at a preset first rate, and control the torque of the engine to drop to a first torque threshold;

[0009] S3: Continuously detect and obtain the real-time speed of the engine, and when the real-time speed of the engine drops to a preset first speed threshold, control the torque of the engine to rise according to the real-time speed of the engine;

[0010] S4: During the process of the engine torque rising, continuously detect and obtain the real-time pressure of the clutch, and compare and obtain the difference between the real-time pressure of the clutch and the target pressure of the clutch; when the difference is less than a preset pressure threshold, control the torque of the engine to drop to a preset second torque threshold at a preset second rate.

[0011] Adopting the above solution, after the vehicle's accelerator pedal is released, control the opening of the clutch, and control the torque of the engine to drop to the first torque threshold to reduce the engine speed. Further, in order to prevent the engine speed from being lower than the clutch speed and causing shaft penetration, control the torque of the engine to rise according to the real-time speed of the engine to synchronize the engine speed and the clutch speed. Furthermore, in order to achieve a braking feeling when releasing the accelerator pedal, control the torque of the engine to drop to a preset second torque threshold to make the vehicle generate a stable deceleration. Thus, through step-by-step control, the deceleration will not suddenly decrease after releasing the accelerator pedal, the deceleration is smoother, and the driving experience is improved.

[0012] According to another specific embodiment of the present invention, in step S2 of the torque control method for a vehicle engine disclosed in the embodiment of the present invention, the step of controlling the clutch to open at a preset first rate includes: obtaining the real-time speed of the clutch and the real-time speed of the engine when the vehicle's accelerator pedal is released, and determining the preset first rate according to the difference between the real-time speed of the clutch and the real-time speed of the engine; and the preset first rate changes inversely with the difference.

[0013] Adopting the above solution, by obtaining the real-time rotational speed of the clutch and the real-time rotational speed of the engine when the accelerator pedal of the vehicle is released, and determining the opening rate of the clutch based on the real-time rotational speed of the clutch and the real-time rotational speed of the engine. Thus, the problems that the vehicle decelerates slowly after releasing the accelerator or the clutch opens too quickly, resulting in a sense of jerk, are solved.

[0014] According to another specific embodiment of the present invention, in the torque control method of the vehicle engine disclosed in the embodiment of the present invention, the first torque threshold is the minimum ignition advance angle torque of the engine.

[0015] According to another specific embodiment of the present invention, in the torque control method of the vehicle engine disclosed in the embodiment of the present invention, the following steps are further included before step S3:

[0016] S31: Continuously detect and obtain the real-time torque of the clutch, and when the real-time torque of the clutch reaches a preset third torque threshold, control the torque of the clutch to remain unchanged; where the preset third torque threshold is the semi-engagement point torque of the clutch.

[0017] Adopting the above solution, continuously detect the real-time torque of the clutch, and keep the torque of the clutch unchanged when the real-time torque of the clutch reaches the semi-engagement point torque of the clutch. Thus, it is possible to prevent the vehicle from generating a sense of acceleration under the condition of releasing the accelerator.

[0018] According to another specific embodiment of the present invention, in step S3 of the torque control method of the vehicle engine disclosed in the embodiment of the present invention, the step of controlling the torque of the engine to rise according to the real-time rotational speed of the engine includes: when the real-time rotational speed of the engine is less than a preset first rotational speed threshold, continuously detect and obtain the real-time rotational speed of the engine and the real-time rotational speed of the clutch, and determine the real-time inertial torque of the engine according to the first rotational speed threshold, the real-time rotational speed of the clutch when the real-time rotational speed of the engine is equal to the preset first rotational speed threshold, the real-time rotational speed of the engine, the moment of inertia of the engine, and the change rate of the rotational speed of the engine; and control the torque of the engine to rise according to the real-time inertial torque of the engine; where the real-time inertial torque of the engine is calculated according to the following formula:

[0019]

[0020] Where, T Incr is the real-time inertial torque of the engine; J eng is the moment of inertia of the engine; dN engSpd is the change rate of the rotational speed of the engine; N1 EngSpd is the real-time rotational speed of the engine when the real-time rotational speed of the engine is equal to the preset first rotational speed threshold; N1 ClchSpd is the real-time rotational speed of the clutch when the real-time rotational speed of the engine is equal to the preset first rotational speed threshold; N EngSpdis the real-time speed of the engine; N ClchSpd is the real-time speed of the clutch; r is the tire radius of the vehicle; the change rate of the engine speed is calculated according to the following formula:

[0021]

[0022] wherein, N t+1 is the engine speed at time t + 1; N t is the engine speed at time t; Δt is the time difference from time t + 1 to time t.

[0023] Adopting the above scheme, by calculating the real-time inertial torque of the engine to perform real-time control on the torque of the engine, that is, performing torque increase control on the torque of the engine, the problem of noise generated by the engine speed being lower than the clutch speed and causing a draw-through is solved.

[0024] According to another specific embodiment of the present invention, for the torque control method of the vehicle engine disclosed in the embodiment of the present invention, the preset first speed threshold is 250 rpm.

[0025] According to another specific embodiment of the present invention, for the torque control method of the vehicle engine disclosed in the embodiment of the present invention, before step S4, it further includes:

[0026] S41: Obtain the real-time speed of the engine and the real-time speed of the clutch. When it is determined that both the real-time speed of the engine and the real-time speed of the clutch are less than the preset second speed threshold, enter step S42;

[0027] S42: Continuously detect the real-time speed of the engine and the real-time speed of the clutch, and when the duration that both the real-time speed of the engine and the real-time speed of the clutch are less than the preset second speed threshold is greater than or equal to the preset time threshold, enter step S43;

[0028] S43: Adjust the engine speed according to the real-time speed of the engine and the preset deviation; and control the torque of the clutch to rise to the preset fourth torque threshold.

[0029] Adopting the above scheme, by obtaining the real-time speed of the engine and the real-time speed of the clutch, when the duration that the real-time speed of the engine and the real-time speed of the clutch are less than the second speed threshold is greater than the preset time threshold, adjust the engine speed and control the torque of the clutch to rise. Thus, it is avoided that due to the delay of the hydraulic system, the engine speed drops below the shaft speed and generates noise. And by controlling the engine speed to be adjusted according to the real-time speed of the engine and the preset deviation, it can prevent the engine torque from dropping to a relatively small negative torque and causing the problem of reverse drag braking.

[0030] According to another specific embodiment of the present invention, the preset second rotational speed threshold disclosed in the embodiment of the present invention is 50 rpm; the preset time threshold is 0.1 s; the preset deviation range is 10 rpm to 30 rpm; the preset fourth torque threshold is 10 N·m; the preset pressure threshold is 0.2 bar; the preset second rate range is 50 N·m / S to 100 N·m / S; the preset second torque threshold is the target torque of the engine; and, the formula for the target torque of the engine is:

[0031]

[0032] wherein, M is the vehicle mass, a Tgt is the desired target deceleration; i g is the transmission ratio; i0 is the differential ratio; J Trm is the equivalent inertia of the transmission; J Tire is the inertia of the tire; r is the tire radius; T TgtEng is the target torque of the engine, J Eng is the inertia of the engine flywheel, dn out is the rotational speed change rate of the transmission output shaft; dn Eng is the rotational speed change rate of the engine, f is the rolling resistance coefficient; η is the mechanical efficiency of the transmission; g is the acceleration due to gravity; and, the value range of the desired target deceleration is 0.05g to 0.1g; and, the target pressure of the clutch is determined according to the real-time torque of the clutch.

[0033] According to another specific embodiment of the present invention, in the torque control method of the vehicle engine disclosed in the embodiment of the present invention, in step S4, the step of controlling the torque of the engine to decrease to the preset second torque threshold at a preset second rate further includes: obtaining the real-time torque of the engine, and adjusting the torque of the clutch to rise to the absolute value of the preset second torque threshold according to the absolute value of the real-time torque of the engine; and, after step S4, it further includes:

[0034] S4-1: Control the torque of the engine to remain unchanged at the preset second torque threshold, and control the torque of the clutch to remain unchanged at the absolute value of the preset second torque threshold.

[0035] By adopting the above solution, by controlling the torque of the engine to change to the preset second torque threshold at a preset second rate, and controlling the torque of the clutch to change with the absolute value of the real-time torque of the engine. Thus, a braking feeling is generated when the accelerator pedal is released. Further, when the torque of the engine reaches the target rotational speed of the engine, keeping the torque of the engine unchanged can enable the vehicle to generate a stable braking deceleration, so that the vehicle can decelerate smoothly.

[0036] According to another specific embodiment of the present invention, the embodiment of the present invention also discloses a torque control system for a vehicle engine, which is used to execute the torque control method for the vehicle engine described in the above embodiment. The torque control system for the vehicle engine includes: an information detection module and a control module; the information detection module is connected to the control module; and, the information detection module detects the position of the accelerator pedal of the vehicle; when the accelerator pedal of the vehicle is released, the control module controls the clutch to open at a preset first rate, and controls the torque of the engine to drop to a first torque threshold; the information detection module also continuously detects and obtains the real-time speed of the engine, and when the real-time speed of the engine reaches a preset first speed threshold, the control module receives the real-time speed of the engine and controls the torque of the engine to rise according to the real-time speed of the engine; during the rising process of the torque of the engine, the information detection module also continuously detects and obtains the real-time pressure of the clutch, and compares and obtains the difference between the real-time pressure of the clutch and the target pressure of the clutch; when the difference is less than a preset pressure threshold, the control module controls the torque of the engine to drop to a preset second torque threshold at a preset second rate.

[0037] The beneficial effects of the present invention are:

[0038] The torque control method and system for a vehicle engine provided by the present invention first control the clutch to open at a preset first rate when the accelerator pedal of the vehicle is released, and, control the torque of the engine to drop to a first torque threshold, thereby, making the engine generate negative torque, so that the speed of the engine drops. Further, continuously detect and obtain the real-time speed of the engine, and when the real-time speed of the engine is less than a preset first speed threshold, control the torque of the engine to rise. Thus, preventing the speed of the engine from being lower than the speed of the clutch and generating noise. Furthermore, in order to achieve a braking feeling when releasing the accelerator, control the speed of the engine to drop to a second torque threshold, and, after the torque of the engine drops to the second torque threshold, keep the torque of the engine unchanged, so that the vehicle generates a stable deceleration. Solved the problems of generating shaft penetration noise, sudden change of deceleration, uneven deceleration, and affecting driving comfort caused by the speed of the engine being lower than the speed of the clutch during the deceleration process after releasing the accelerator. Description of the Drawings

[0039] Figure 1 is a schematic diagram of the changes in the engine speed and the clutch speed in the prior art;

[0040] Figure 2 is a schematic flowchart of the torque control method for a vehicle engine provided by an embodiment of the present invention;

[0041] Figure 3 is a schematic diagram of the changes in the engine speed and the clutch speed provided by an embodiment of the present invention;

[0042] Figure 4 It is a schematic diagram showing the changes in the engine speed and the clutch speed when the accelerator is lightly depressed in an embodiment of the present invention;

[0043] Figure 5 It is a graph showing the relationship between the difference in the engine speed and the clutch speed and a preset first rate in an embodiment of the present invention;

[0044] Figure 6 It is a graph showing the relationship between the real-time torque of the clutch and the target pressure of the clutch in an embodiment of the present invention;

[0045] Figure 7 It is a schematic diagram showing the synchronous control process of the engine speed and the clutch speed in an embodiment of the present invention;

[0046] Figure 8 It is a system diagram of the torque control of a vehicle engine in an embodiment of the present invention.

[0047] Reference numerals:

[0048] 1. Information detection module; 2. Control module. Detailed implementation manners

[0049] The following specific embodiments illustrate the implementation manners of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Although the description of the present invention will be introduced in conjunction with preferred embodiments, this does not mean that the features of this invention are limited to this implementation manner. On the contrary, the purpose of introducing the invention in conjunction with the implementation manner is to cover other alternatives or modifications that may be extended based on the claims of the present invention. In order to provide a deep understanding of the present invention, many specific details will be included in the following description. The present invention can also be implemented without these details. In addition, in order to avoid confusing or obscuring the key points of the present invention, some specific details will be omitted in the description. It should be noted that, without conflict, the embodiments and the features in the embodiments of the present invention can be combined with each other.

[0050] It should be noted that in this specification, similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0051] In the description of this embodiment, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "inner", "bottom", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the inventive product is usually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0052] The terms "first", "second", etc. are only used for descriptive distinction and should not be construed as indicating or implying relative importance.

[0053] In the description of this embodiment, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in this embodiment can be understood according to specific circumstances.

[0054] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0055] To solve the problems in the prior art that after the vehicle releases the accelerator pedal, the engine speed is lower than the clutch speed, resulting in noise, sudden deceleration changes, and uneven deceleration. Embodiments of the present invention disclose a torque control method and system for a vehicle engine. Specifically, referring to Figure 2 , the torque control method for a vehicle engine provided by the embodiments of the present invention includes the following steps:

[0056] S1: Obtain the position of the vehicle's accelerator pedal, and determine whether the vehicle's accelerator pedal is released according to the position of the vehicle's accelerator pedal; if so, execute step S2; if not, continue to determine whether the vehicle's accelerator pedal is released.

[0057] S2: Control the clutch to open at a preset first rate, and control the torque of the engine to drop to a first torque threshold.

[0058] S3: Continuously detect and obtain the real-time speed of the engine, and when the real-time speed of the engine drops to a preset first speed threshold, control the torque of the engine to rise according to the real-time speed of the engine.

[0059] S4: During the torque increase process of the engine, continuously detect and obtain the real-time pressure of the clutch, and compare the difference between the real-time pressure of the clutch and the target pressure of the clutch; when the difference is less than a preset pressure threshold, control the torque of the engine to drop to a preset second torque threshold at a preset second rate.

[0060] With the above solution, after the vehicle's accelerator pedal is released, the opening of the clutch is controlled, and the torque of the engine is controlled to decrease to the first torque threshold, so that the engine speed decreases. Further, to prevent the engine speed from being lower than the rotational speed of the clutch's through shaft, the torque of the engine is controlled to increase according to the real-time engine speed, so that the engine speed and the clutch speed are synchronized. Even further, to achieve a braking feeling when releasing the accelerator, the torque of the engine is controlled to decrease to the preset second torque threshold, so that the vehicle generates a stable deceleration. Thus, through step-by-step control, the deceleration does not suddenly decrease after releasing the accelerator, the deceleration is smoother, and the driving experience is improved.

[0061] Specifically, refer to Figure 2-8 to illustrate the method for controlling the torque of the engine provided in this embodiment.

[0062] Before illustrating the method for controlling the torque of the clutch provided in this embodiment, the structure of the dual-clutch transmission system needs to be described. In this embodiment, the dual-clutch transmission system includes an engine, a transmission, and a clutch, and the clutch is arranged between the engine and the transmission. The clutch can cut off or connect the torque transmission between the engine and the transmission. The dual-clutch transmission system in this embodiment has no essential difference from the dual-clutch transmission system in the prior art, and will not be elaborated in this embodiment.

[0063] It is also necessary to describe the changes in the engine speed and the clutch speed after the vehicle's accelerator pedal is released.

[0064] The present invention controls the torque of the engine so that the engine speed gradually approaches the clutch speed until it is synchronized with the clutch speed. Specifically, as Figure 3 shown, the present invention controls the torque of the engine to prevent the engine speed from being lower than the clutch speed and generating through shaft noise, and controls the torque of the engine to smoothly combine the engine speed and the clutch speed, solving the problems of generating noise after releasing the accelerator, causing sudden changes in deceleration, uneven deceleration, and affecting driving comfort.

[0065] Further, as Figure 4 shown, the method for controlling the torque of the vehicle engine of the present invention is applicable to the vehicle during low-speed driving, that is, when the vehicle speed is between 8 km / h and 20 km / h, and the driver needs to continuously release and press the accelerator pedal for following a vehicle. Or the driver changes the vehicle from an accelerating state to a coasting state, from pressing the accelerator to releasing the accelerator. Since the vehicle speed is relatively low, the clutch adopts a starting strategy when pressing the accelerator, that is, the engine speed first increases, and then the engine speed and the clutch speed are gradually synchronized by combining with the clutch speed, which is beneficial to improving power performance and smoothness.

[0066] Next, the control method for the torque of the vehicle engine provided in this embodiment will be described.

[0067] First, perform step S1 to obtain the position of the vehicle's accelerator pedal, and determine whether the vehicle's accelerator pedal is released according to the position of the vehicle's accelerator pedal; if so, perform step S2; if not, continue to determine whether the vehicle's accelerator pedal is released.

[0068] Specifically, obtain the position of the vehicle's accelerator pedal. When the accelerator pedal position is the original state position, the vehicle's accelerator pedal is released. If the pedal position is a non - original state position, the accelerator pedal is not released. If the accelerator pedal is not released, continue to judge until the accelerator pedal position is released and then perform step S2.

[0069] Next, perform step S2 to control the clutch to open at a preset first rate, and control the torque of the engine to drop to a first torque threshold.

[0070] Specifically, when the accelerator pedal is released, the engine speed is relatively high at this time. Control the clutch to open at a preset first rate. And control the torque of the engine to drop to the first torque threshold so that the torque of the engine is negative, thereby reducing the engine speed.

[0071] Further, in step S2, the step of controlling the clutch to open at a preset first rate includes: obtaining the real - time speed of the clutch and the real - time speed of the engine when the vehicle's accelerator pedal is released, and determining the preset first rate according to the difference between the real - time speed of the clutch and the real - time speed of the engine.

[0072] Specifically, as Figure 5 shown, obtain the real - time speed of the clutch and the real - time speed of the engine when the vehicle's accelerator pedal is released, and determine the preset first rate according to the difference between the real - time speed of the clutch and the real - time speed of the engine. As Figure 5 shown, when the difference between the speed of the clutch and the speed of the engine is 2000 rpm, the clutch opens at 100 N·M / S at this time. When the difference between the speed of the clutch and the speed of the engine is 0, the clutch opens at 500 N·M / S at this time. That is to say, the preset first rate changes inversely with the difference.

[0073] Furthermore, the first torque threshold is the minimum ignition - advance - angle torque of the engine.

[0074] Specifically, the ignition advance angle is the angle that the crankshaft turns from when the spark plug starts to ignite to when the piston reaches the top dead center. The larger the ignition advance angle, the greater the output torque; the smaller the ignition advance angle, the smaller the output torque.

[0075] Next, perform step S3, continuously detect and obtain the real-time engine speed. When the real-time engine speed drops to a preset first speed threshold, control the torque of the engine to increase according to the real-time engine speed.

[0076] It should be noted that before performing step S3, step S31 needs to be performed, continuously detect and obtain the real-time torque of the clutch, and when the real-time torque of the clutch reaches a preset third torque threshold, control the torque of the clutch to remain unchanged.

[0077] Specifically, continuously obtain the real-time torque of the clutch, and determine whether the real-time torque of the clutch reaches the preset third torque threshold. If so, control the torque of the clutch to remain unchanged. If not, continue to judge until the real-time torque of the clutch reaches the preset third torque threshold.

[0078] Among them, the preset third torque threshold is the semi-engagement point torque of the clutch. That is to say, in order to prevent the vehicle from having an acceleration feeling under the condition of releasing the accelerator pedal, the semi-engagement point torque of the clutch is selected as the threshold, generally set to 0 N·m.

[0079] It should be noted that the preset third torque threshold can be determined according to actual experience, and this embodiment does not limit it.

[0080] Next, perform step S3. And in step S3, the step of controlling the torque of the engine to increase according to the real-time engine speed includes: when the real-time engine speed is less than the preset first speed threshold, continuously detect and obtain the real-time engine speed and the real-time speed of the clutch, and determine the real-time inertial torque of the engine according to the first speed threshold, the real-time speed of the clutch when the real-time engine speed is equal to the preset first speed threshold, the real-time engine speed, the moment of inertia of the engine, and the change rate of the engine speed.

[0081] Specifically, when the real-time engine speed is less than the preset first speed threshold, obtain the real-time engine speed and the real-time speed of the clutch. And determine the real-time inertial torque of the engine according to the real-time engine speed, the real-time speed of the clutch, the moment of inertia of the engine, and the change rate of the engine speed when the real-time engine speed is equal to the preset first speed threshold.

[0082] And control the torque of the engine to increase according to the real-time inertial torque of the engine.

[0083] That is to say, when the real-time speed of the engine is less than the preset first speed threshold, the torque of the engine is controlled to change according to the real-time inertial torque of the engine. That is, at every moment, a real-time moment of inertia of the engine can be obtained. At each moment, the torque of the engine is the real-time inertial torque of the engine, and the real-time inertial torque of the engine is a value that changes according to the real-time speed of the engine and the real-time speed of the clutch.

[0084] The real-time inertial torque of the engine is calculated according to the following formula:

[0085]

[0086] Wherein, T Incr is the real-time inertial torque of the engine; J eng is the moment of inertia of the engine; dN engSpd is the change rate of the speed of the engine; N1 EngSpd is the real-time speed of the engine when the real-time speed of the engine is equal to the preset first speed threshold; N1 ClchSpd is the real-time speed of the clutch when the real-time speed of the engine is equal to the preset first speed threshold; N EngSpd is the real-time speed of the engine; N ClchSpd is the real-time speed of the clutch; r is the radius of the vehicle tire.

[0087] Specifically, the moment of inertia of the engine can be determined through specific tests or calculated through existing moment of inertia calculation formulas of the engine. For example, by measuring or calculating the moment of inertia of each relevant moving part of the engine with respect to the crankshaft center line and summing them up to obtain the moment of inertia of the engine.

[0088] Moreover, the real-time speed of the engine and the real-time speed of the clutch can be determined by a speed sensor.

[0089] The change rate of the speed of the engine is calculated according to the following formula:

[0090]

[0091] Wherein, N t+1 is the speed of the engine at time t + 1; N t is the speed of the engine at time t; Δt is the time difference from time t + 1 to time t.

[0092] Wherein, the speed of the engine at any moment can be determined by the speed display on the dashboard of the vehicle.

[0093] Furthermore, the preset first speed threshold is 250 rpm. Specifically, the preset first speed threshold is determined according to actual experience. As long as it is ensured that the speed of the engine is not lower than the speed of the clutch.

[0094] Next, perform step S4. During the torque rise process of the engine, continuously detect and obtain the real-time pressure of the clutch, and compare the difference between the real-time pressure of the clutch and the target pressure of the clutch; when the difference is less than the preset pressure threshold, control the torque of the engine to decrease to the preset second torque threshold at the preset second rate.

[0095] Furthermore, before performing step S4, it is also necessary to perform step S41. Obtain the real-time speed of the engine and the real-time speed of the clutch. When it is determined that both the real-time speed of the engine and the real-time speed of the clutch are less than the preset second speed threshold, enter step S42.

[0096] Specifically, when both the real-time speed of the engine and the real-time speed of the clutch are less than the preset second speed threshold, it indicates that the speeds of the engine and the clutch are tending to be synchronized.

[0097] And, the preset second speed threshold is 50 rpm. It should be noted that the preset second speed threshold is determined according to actual experience. It can also be other values, and those skilled in the art can determine the second speed threshold according to actual experience. This embodiment does not limit this.

[0098] Next, perform step S42. Continuously detect the real-time speed of the engine and the real-time speed of the clutch, and when the duration during which both the real-time speed of the engine and the real-time speed of the clutch are less than the preset second speed threshold is greater than or equal to the preset time threshold, enter step S43.

[0099] Specifically, when the real-time speed of the engine and the real-time speed of the clutch are less than 50 rpm, the speeds of the engine and the clutch tend to be synchronized. In order to determine that the real-time speed of the engine and the real-time speed of the clutch are tending to be synchronized, when it is determined that the duration during which the real-time speed of the engine and the real-time speed of the clutch are less than 50 rpm is greater than or equal to the preset time threshold, it is determined that the real-time speed of the engine and the real-time speed of the clutch have been synchronized.

[0100] And, the preset time threshold is 0.1 s. It should be noted that the preset time threshold is generally about 0.1 s, but those skilled in the art can also set other time thresholds, such as 0.2 s, 0.15 s, etc. The preset time threshold can be determined according to actual needs. This embodiment does not limit this.

[0101] Furthermore, perform step S43. Adjust the speed of the engine according to the real-time speed of the engine and the preset deviation; and control the torque of the clutch to rise to the preset fourth torque threshold.

[0102] Specifically, in step S2, after increasing the torque of the engine according to the real-time speed of the engine, the torque of the engine at this time is positive torque. In order to maintain the positive torque of the engine, the engine needs to enter the idle state at this time. However, in the existing idle control of the engine, only the proportional and integral in the PID algorithm are considered, and the differential is not considered. Therefore, there is a certain error. Moreover, due to the delayed response of the hydraulic system, when the speed of the clutch increases, the speed of the engine is lower than the speed of the clutch through the shaft. If the speed of the engine is not controlled, it will cause the engine to drop from the current torque to a relatively small negative torque, resulting in reverse drag braking. Therefore, in this embodiment, the idle speed of the engine is adjusted. This idle speed adjustment is adjusted by adding a preset deviation to the real-time speed of the engine, and the torque of the clutch is controlled to rise to a preset fourth torque threshold.

[0103] Among them, the preset deviation range is 10 rpm to 30 rpm. It should be noted that if the deviation range is too large, it will cause the vehicle to accelerate. Therefore, the deviation range is generally small. Of course, those skilled in the art can also select the deviation range according to actual needs, and this embodiment does not limit this.

[0104] The preset fourth torque threshold is 10 N·m. It should be noted that the preset fourth torque threshold can also be determined according to actual experience, and this embodiment does not limit this.

[0105] Next, step S4 is executed again. During the rising process of the torque of the engine, the real-time pressure of the clutch is continuously detected and obtained, and the difference between the real-time pressure of the clutch and the target pressure of the clutch is compared; when the difference is less than the preset pressure threshold, the torque of the engine is controlled to drop to the preset second torque threshold at the preset second rate.

[0106] Specifically, by obtaining the real-time pressure of the clutch, and when the difference between the real-time pressure of the clutch and the target pressure of the clutch is less than the preset pressure threshold, in order to achieve the braking feeling when releasing the accelerator pedal, the torque of the engine is controlled to drop to the preset second torque threshold at the preset second rate.

[0107] Among them, the target pressure of the clutch is determined according to the real-time torque of the clutch. Specifically, as Figure 6 shown, the target pressure of the clutch corresponds to the real-time torque of the clutch. By obtaining the real-time torque of the clutch, the target pressure of the clutch at this torque can be determined. Therefore, it is necessary to continuously calculate the difference between the real-time pressure of the clutch and the corresponding target pressure of the clutch at any torque of the clutch.

[0108] The preset pressure threshold is 0.2 bar. It should be noted that the preset pressure threshold is determined according to actual experience. Those skilled in the art can determine the preset pressure threshold according to actual needs, and this embodiment does not limit it.

[0109] The preset second rate range is from 50 N·m / S to 100 N·m / S. It should be noted that the preset second rate is achieved through calibration. Those skilled in the art can calibrate it according to actual needs, and this embodiment does not limit it.

[0110] The preset second torque threshold is the target torque of the engine; and, the formula for the target torque of the engine is:

[0111]

[0112] where M is the vehicle mass, a Tgt is the desired target deceleration; i g is the transmission ratio; i0 is the differential ratio; J Trm is the equivalent inertia of the transmission; J Tire is the inertia of the tire; r is the tire radius; T TgtEng is the target torque of the engine, J Eng is the inertia of the engine flywheel, dn out is the rotational speed change rate of the transmission output shaft, dn Eng is the rotational speed change rate of the engine, f is the rolling resistance coefficient; η is the mechanical efficiency of the transmission; g is the acceleration due to gravity;

[0113] where the range of the desired target deceleration is from 0.05g to 0.1g. It should be noted that by only calibrating the desired target deceleration, the target torque of the engine can be determined, and other parameters are known quantities.

[0114] It should also be noted that the target torque of the engine is calculated and converted into the target torque of the engine according to the vehicle dynamics formula. Among them, the vehicle dynamics formula is:

[0115]

[0116] where M is the vehicle mass, a Tgt is the desired target deceleration, i g is the transmission ratio, i0 is the differential ratio, J Trm is the equivalent inertia of the transmission, J Tire is the inertia of the tire, r is the tire radius, T TgtEng is the target torque of the engine, J Eng is the inertia of the engine flywheel, dn out is the rotational speed change rate of the transmission output shaft, dn Engis the engine speed change rate, f is the rolling resistance coefficient, η is the mechanical efficiency of the transmission; g is the acceleration due to gravity, C D is the drag coefficient, A is the frontal area, and V is the vehicle speed.

[0117] Since the vehicle speed is relatively low, the influence of the vehicle speed is ignored. At the same time, it is assumed that the vehicle is driving on a flat road. After further simplification of the above formula, the target torque formula of the engine is obtained.

[0118] Among them, the transmission ratio of the transmission is determined by dividing the number of teeth of the driven gear of the transmission by the number of teeth of the driving gear. The differential ratio is determined by dividing the number of teeth of the driven gear of the differential by the number of teeth of the driving gear.

[0119] The equivalent condition for the equivalent inertia of the transmission is that the kinetic energies are equal. That is, at any moment, the kinetic energy of the equivalent component is equal to the sum of the kinetic energies of all moving components in the machine. Assume that the kinetic energy of the i-th moving component in the engine is E i (i = 1, 2, 3.......n), then the equivalent moment of inertia J satisfies the following formula:

[0120] The inertia of the tire and the inertia of the flywheel of the engine can both be obtained through experiments.

[0121] The mechanical efficiency of the transmission can be taken as 0.98 or 1, or it can also be obtained through formulas or experiments.

[0122] The rolling resistance coefficient can be 0.02 or other values. Those skilled in the art can set it according to the actual situation, and this embodiment does not limit it.

[0123] The speed change rate of the output shaft of the transmission is determined by dividing the difference between the speed of the output shaft of the transmission at time t + 1 and the speed of the output shaft of the transmission at time t by the time difference between t + 1 and t.

[0124] The change rate of the engine speed is determined by dividing the difference between the engine speed at time t + 1 and the engine speed at time t by the time difference between t + 1 and t. Among them, time t is the first moment when the difference between the actual pressure and the target pressure of the clutch is less than the preset pressure threshold, and time t + 1 is the next moment when the difference between the actual pressure and the target pressure of the clutch is less than the preset pressure threshold. It should be noted that the time difference between time t + 1 and time t can be set according to actual needs. That is to say, it can be 0.01m milliseconds or 0.05 milliseconds, etc.

[0125] It should be noted that at this stage, the main purpose is to control the torque of the engine to maintain a stable range without change. That is to say, when the difference between the real-time pressure of the clutch and the target pressure of the clutch is less than the preset pressure difference, both the engine speed and the clutch speed change at a gradually stable rate of change. Therefore, it is possible to obtain the rate of change of the engine speed and the rate of change of the output shaft at any time difference, and the rate of change is a value that tends to be stable.

[0126] It should also be noted that this formula is used to calculate the target torque of the engine, and the torque of the engine is controlled to change to the target torque of the engine at a preset second rate. The purpose is to make the engine speed and the clutch speed more stably combined to enable the vehicle to generate a stable braking deceleration, and all parameter values can be determined according to actual experience.

[0127] Furthermore, the step of controlling the torque of the engine to decrease to a preset second torque threshold at a preset second rate further includes: obtaining the real-time torque of the engine, and adjusting the torque of the clutch to rise to the absolute value of the preset second torque threshold according to the absolute value of the real-time torque of the engine.

[0128] Specifically, the real-time torque of the engine changes to the preset second torque threshold at a preset second rate. At the same time, the torque of the clutch also changes in real time, and it changes according to the absolute value of the real-time torque of the engine.

[0129] Therefore, it will finally change to the absolute value of the target torque of the engine.

[0130] And, after step S4, it further includes S4-1: controlling the torque of the engine to remain unchanged at the preset second torque threshold, and controlling the torque of the clutch to remain unchanged at the absolute value of the preset second torque threshold.

[0131] Specifically, when the real-time torque of the engine reaches the target torque of the engine, the current target torque of the engine is maintained without change. And, the torque of the clutch is maintained to remain unchanged at the absolute value of the preset second torque threshold.

[0132] Thus, a stable braking deceleration is generated for the vehicle.

[0133] It should be noted that the torque of the engine remains unchanged, and the road resistance changes gradually. Therefore, the vehicle will generate a stable deceleration braking. Even on a slope, the target torque of the engine still remains unchanged.

[0134] With the above solution, first, when the accelerator pedal of the vehicle is released, the clutch is controlled to open at a preset first rate, and the torque of the engine is controlled to drop to a first torque threshold. Thus, a negative torque is generated by the engine, causing the engine speed to decrease. Further, the real-time speed of the engine is continuously detected and obtained. When the real-time speed of the engine is less than a preset first speed threshold, the torque of the engine is controlled to increase. Thus, it is prevented that the engine speed is lower than the clutch speed, generating noise. Furthermore, in order to achieve a braking feeling when releasing the accelerator, the engine speed is controlled to drop to a second torque threshold, and after the engine torque drops to the second torque threshold, the engine torque is kept unchanged, causing the vehicle to generate a stable deceleration.

[0135] An embodiment of the present invention also discloses a torque control system for a vehicle engine, which is used to execute the torque control method of the vehicle engine disclosed in the above embodiment.

[0136] As Figure 8 shown, the torque control system of the vehicle engine includes an information detection module 1 and a control module 2.

[0137] The information detection module 1 is connected to the control module 2; and the information detection module 1 detects the position of the accelerator pedal of the vehicle. When the accelerator pedal of the vehicle is released, the control module 2 controls the clutch to open at a preset first rate and controls the torque of the engine to drop to a first torque threshold.

[0138] The information detection module 1 also continuously detects and obtains the real-time speed of the engine. When the real-time speed of the engine reaches a preset first speed threshold, the control module 2 receives the real-time speed of the engine and controls the torque of the engine to increase according to the real-time speed of the engine.

[0139] During the process of the engine torque increasing, the information detection module 1 also continuously detects and obtains the real-time pressure of the clutch, and compares the difference between the real-time pressure of the clutch and the target pressure of the clutch. When the difference is less than a preset pressure threshold, the control module 2 controls the torque of the engine to drop to a preset second torque threshold at a preset second rate.

[0140] Specifically, the information detection module 1 includes a position detector for detecting the position of the accelerator pedal of the vehicle, a speed sensor for collecting the real-time speed of the engine and the real-time speed of the clutch, and a pressure sensor for collecting the real-time pressure of the clutch. A torque calculator is used to calculate the real-time torque of the engine and the real-time torque of the clutch.

[0141] The control module 2 includes a transmission controller, an engine controller, and a clutch controller. The transmission controller is respectively connected to the engine controller and the clutch controller.

[0142] Among them, asFigure 7 As shown, in the first stage, the engine speed is relatively high. At this moment, the transmission controller sends a clutch opening request to the clutch controller. The clutch controller controls the clutch to open at a preset first rate. The transmission controller sends a torque reduction request to the engine controller, and the engine controller controls the engine torque to drop to the first torque threshold. Moreover, the torque calculator continuously calculates the real-time torque of the clutch and sends the real-time torque of the clutch to the transmission controller. When the real-time torque of the clutch is less than the preset third torque threshold, the transmission controller sends a request to the clutch controller, and the clutch controller controls the torque of the clutch to remain unchanged.

[0143] Furthermore, in the second stage, the speed sensor collects the real-time engine speed and sends the real-time engine speed to the transmission controller. When the real-time engine speed is less than the preset first speed threshold, the transmission controller sends a torque increase request to the engine controller, and the engine controller controls the engine torque to increase according to the real-time inertial torque of the engine. At the same time, the speed sensor continuously collects the real-time engine speed and the real-time clutch speed and sends the real-time engine speed and the real-time clutch speed to the transmission controller. When both the real-time engine speed and the real-time clutch speed are less than the preset second speed threshold and the duration is greater than or equal to the preset time threshold, it is determined that the synchronization of the clutch speed and the engine speed is completed.

[0144] Entering the third stage, when both the real-time engine speed and the real-time clutch speed are less than the preset second speed threshold and the duration is greater than or equal to the preset time threshold, the transmission controller sends an idle request to the engine controller, and the engine controller controls the engine speed to change according to the real-time engine speed plus the preset deviation. At the same time, the transmission controller sends a torque increase request to the clutch controller, and the clutch controller controls the torque of the clutch to increase to the preset fourth torque threshold. The pressure collector continuously collects the real-time pressure of the clutch and sends the real-time pressure of the clutch to the transmission controller. When the difference between the real-time pressure of the clutch and the target pressure of the clutch is less than the preset pressure threshold, it is considered that the clutch is in the engaged state with the engine at this moment.

[0145] Entering the fourth stage, when the difference between the real-time pressure of the clutch and the target pressure of the clutch is less than the preset pressure threshold, the transmission controller sends a torque reduction request to the engine controller, and the engine controller controls the engine torque to drop to the preset second torque threshold at a preset second rate. Moreover, the transmission controller sends a torque increase request to the clutch controller, and the clutch controller controls the torque of the clutch to change according to the absolute value of the real-time torque of the engine.

[0146] Entering the fifth stage, when the real-time torque of the engine reaches the preset second torque threshold, the transmission controller sends a maintenance request to the engine controller and the clutch controller. The engine controller controls the torque of the engine to maintain the current torque unchanged, and the clutch controller controls the torque of the clutch to maintain the current torque unchanged, so as to make the vehicle generate a stable braking deceleration.

[0147] Although the present invention has been illustrated and described with reference to certain preferred embodiments thereof, those of ordinary skill in the art should understand that the above content is a further detailed description of the present invention in conjunction with specific embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. Those skilled in the art can make various changes in form and detail, including making several simple deductions or substitutions, without departing from the spirit and scope of the present invention.

Claims

1. A torque control method for a vehicle engine, characterized in that, It includes the following steps: S1: Obtain the position of the vehicle's accelerator pedal, and determine whether the vehicle's accelerator pedal is released according to the position of the vehicle's accelerator pedal; If so, execute step S2; If not, continue to determine whether the vehicle's accelerator pedal is released; S2: Control the clutch to open at a preset first rate, and control the torque of the engine to drop to a first torque threshold; S3: Continuously detect and obtain the real-time speed of the engine. When the real-time speed of the engine drops to a preset first speed threshold, control the torque of the engine to rise according to the real-time speed of the engine, including: When the real-time speed of the engine is less than the preset first speed threshold, continuously detect and obtain the real-time speed of the engine and the real-time speed of the clutch, and determine the real-time inertial torque of the engine according to the first speed threshold, the real-time speed of the clutch when the real-time speed of the engine is equal to the preset first speed threshold, the real-time speed of the engine, the moment of inertia of the engine, and the change rate of the engine speed; and, Control the torque of the engine to rise according to the real-time inertial torque of the engine; where The real-time inertial torque of the engine is calculated according to the following formula: where is the real-time inertial torque of the engine; is the moment of inertia of the engine; is the change rate of the engine speed; is the real-time engine speed when the real-time engine speed is equal to the preset first speed threshold; is the real-time clutch speed when the real-time engine speed is equal to the preset first speed threshold; is the real-time engine speed; is the real-time clutch speed; r is the tire radius of the vehicle; The rate of change of the rotational speed of the engine is calculated according to the following formula: where is the rotational speed of the engine at time t + 1; is the rotational speed of the engine at time t; is the time difference from time t + 1 to time t; S4: During the process of the engine torque rising, continuously detect and obtain the real-time pressure of the clutch, and compare and obtain the difference between the real-time pressure of the clutch and the target pressure of the clutch; when the difference is less than a preset pressure threshold, control the torque of the engine to drop to a preset second torque threshold at a preset second rate.

2. The torque control method for a vehicle engine according to claim 1, characterized in that, In step S2, the step of controlling the clutch to open at a preset first rate includes: Obtain the real-time speed of the clutch and the real-time speed of the engine when the vehicle's accelerator pedal is released, and determine the preset first rate according to the difference between the real-time speed of the clutch and the real-time speed of the engine; and, The preset first rate changes inversely with the difference.

3. The torque control method for a vehicle engine according to claim 2, characterized in that, The first torque threshold is the minimum ignition advance angle torque of the engine.

4. The torque control method for a vehicle engine according to claim 3, characterized in that, Before step S3, the following steps are further included: S31: Continuously detect and obtain the real-time torque of the clutch, and when the real-time torque of the clutch reaches a preset third torque threshold, control the torque of the clutch to remain unchanged; Where The preset third torque threshold is the semi-engagement point torque of the clutch.

5. The torque control method for a vehicle engine according to claim 4, characterized in that, The preset first speed threshold is 250 rpm.

6. The torque control method for a vehicle engine according to claim 5, characterized in that, Before step S4, it also includes: S41: Obtain the real-time speed of the engine and the real-time speed of the clutch, and when it is determined that both the real-time speed of the engine and the real-time speed of the clutch are less than a preset second speed threshold, enter step S42; S42: Continuously detect the real-time speed of the engine and the real-time speed of the clutch, and when the duration during which both the real-time speed of the engine and the real-time speed of the clutch are less than the preset second speed threshold is greater than or equal to a preset time threshold, enter step S43; S43: Adjust the engine speed according to the real-time speed of the engine and a preset deviation; and control the torque of the clutch to rise to a preset fourth torque threshold.

7. The torque control method for a vehicle engine according to claim 6, characterized in that, The preset second speed threshold is 50 rpm; the preset time threshold is 0.1 s; the preset deviation range is 10 rpm to 30 rpm; the preset fourth torque threshold is 10 N·m; the preset pressure threshold is 0.2 bar; the preset second rate range is 50 N·m / s to 100 N·m / s; the preset second torque threshold is the target torque of the engine; and, The target torque formula of the engine is as follows: where M is the vehicle mass, is the desired target deceleration; is the transmission ratio; Differential ratio; is the equivalent inertia of the transmission; is the inertia of the tire; is the tire radius; is the target torque of the engine, is the flywheel inertia of the engine, is the rotational speed change rate of the transmission output shaft; is the rotational speed change rate of the engine, is the rolling resistance coefficient; is the mechanical efficiency of the transmission; g is the acceleration due to gravity; and, the value range of the desired target deceleration is 0.05g to 0.1g; and, the target pressure of the clutch is determined according to the real-time torque of the clutch.

8. The torque control method for a vehicle engine according to claim 7, characterized in that, In step S4, the step of controlling the torque of the engine to decrease to the preset second torque threshold at a preset second rate further includes: Obtain the real-time torque of the engine, and adjust the torque of the clutch to rise to the absolute value of the preset second torque threshold according to the absolute value of the real-time torque of the engine. And, after step S4, it further includes: S4-1: Control the torque of the engine to remain unchanged at the preset second torque threshold, and control the torque of the clutch to remain unchanged at the absolute value of the preset second torque threshold.

9. A torque control system for a vehicle engine, characterized in that, It executes the torque control method of a vehicle engine according to any one of claims 1-8. The torque control system of the vehicle engine includes: an information detection module and a control module; the information detection module is connected to the control module; and, The information detection module detects the position of the accelerator pedal of the vehicle. When the accelerator pedal of the vehicle is released, the control module controls the clutch to open at the preset first rate and controls the torque of the engine to decrease to the first torque threshold. The information detection module also continuously detects and obtains the real-time speed of the engine. When the real-time speed of the engine reaches a preset first speed threshold, the control module receives the real-time speed of the engine and controls the torque of the engine to rise according to the real-time speed of the engine. During the rising process of the torque of the engine, the information detection module also continuously detects and obtains the real-time pressure of the clutch, and compares the difference between the real-time pressure of the clutch and the target pressure of the clutch; when the difference is less than a preset pressure threshold, the control module controls the torque of the engine to decrease to the preset second torque threshold at the preset second rate.

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