CN102494127A - Method for implementing quick gear shift for automated mechanical transmission under brake condition - Google Patents

Abstract

The invention discloses a method for fast gear shifting under braking of a mechanical automatic transmission. The driving vehicle first judges whether there is a braking signal, and if there is no braking, the traditional gear shifting rule is executed; Shifting schedule, brake shifting schedule includes the following steps: A. The vehicle is running normally in the original gear, and the engine speed is judged. If the engine speed is greater than the engine idle speed at this time, keep the original gear for normal driving; Speed, enter step B; B. Judging the transmission gear at this time, if the transmission is in the first gear, enter the vehicle start control process; if the transmission gear is greater than the first gear at this time, enter step C; C. Disengage the clutch and calculate the target according to the vehicle speed Gear, shift into the target gear after the brake is released; D. Engage the clutch; the gear shift is completed. The invention reduces the number of gear shifts under braking, can quickly satisfy the driver's driving intention, and successfully realizes the gear shifting function of the mechanical automatic transmission under braking.

Description

A method for quick gear shifting under braking of a mechanical automatic transmission

technical field

The invention relates to the technical field of control of automatic transmissions for automobiles, in particular to a method for shifting gears of a mechanical automatic transmission under braking.

Background technique

The automatic mechanical transmission (AMT) judges the driver's intention according to the opening of the accelerator pedal and the brake signal, and the electronic control unit of the automatic transmission controls the actuator to automatically complete the process of removing gear, selecting gear and engaging gear. AMT has the advantages of high transmission efficiency, good fuel economy, simple structure, and low cost. Since most domestic heavy-duty commercial vehicles are equipped with fixed-shaft mechanical transmissions, AMT has broad development prospects. A large number of mechanical automatic transmissions have been developed in China. Related research. For large vehicles with heavy weight such as heavy commercial vehicles and urban buses, the requirements for comfort are not high. When AMT is used on such vehicles, the impact of shifting gears is small, and at the same time, it can effectively reduce the driver's labor intensity and Therefore, it has been widely used and is very suitable for my country's national conditions.

In recent years, multi-speed is one of the development directions of mechanical automatic transmission, and this trend is more prominent in the field of heavy commercial vehicles. At present, most of the gearboxes used in my country's newly launched medium and heavy commercial vehicles are equipped with 9-speed, 12-speed or even 16-speed transmissions, and the proportion is constantly expanding. Under normal circumstances, vehicles equipped with mechanical automatic transmissions are shifted according to the traditional shift rules formulated by designers and developers. However, in the case of braking, how to quickly realize the shift operation of the mechanical automatic transmission, especially the multi-gear mechanical automatic transmission, reduce the number of shifts, quickly realize the driver's driving intention, and improve the driving safety of the vehicle is worthwhile. researched.

Contents of the invention

In view of this, the purpose of the present invention is to provide a method for fast shifting of a mechanical automatic transmission under braking, which can quickly realize the shifting operation of the mechanical automatic transmission, reduce the number of shifts, and enhance the handling of the car , improving the safety of the vehicle.

The purpose of the present invention is achieved by the following technical solutions:

A method for quickly shifting gears under braking by a mechanical automatic transmission, which is obtained by adding an electronic control unit and an automatic actuator on the basis of a dry clutch and a fixed-shaft gear-type stepped mechanical transmission , which is characterized in that: the electronic control unit judges whether there is a braking signal, if there is no braking signal, the traditional shifting schedule is executed; if there is a braking signal, the braking shifting schedule is executed, and the braking shifting schedule includes The following steps:

Step A: The vehicle runs normally in the original gear, and the electronic control unit obtains the engine speed through the CAN bus. If the engine speed is greater than the engine idle speed at this time, keep the original gear for normal driving; if the engine speed is less than or equal to the idle speed, enter step B;

Step B: Determine the gear position of the transmission at this time. If the transmission is in the first gear, enter the vehicle start control process; if the transmission gear is greater than the first gear at this time, enter step C;

Step C: disengage the clutch, the electronic control unit calculates the target gear according to the vehicle speed, and shift into the target gear after the brake is released;

Step D: Engage the clutch and the gear shift is complete.

The beneficial effects of the present invention are:

1. The shift strategy of the present invention has simple steps, convenient control and easy implementation;

2. The present invention performs braking under normal circumstances, that is, when the engine speed is greater than the engine idle speed, the original gear of the transmission is maintained, and the braking force of the brake and the reverse torque of the engine can be fully utilized to perform braking and deceleration;

3. During emergency braking at high speeds and high gears, the engine speed will drop rapidly. The jump gear downshift control strategy is adopted to reduce the number of gear shifts and avoid insufficient power or even The problem of engine stalling ensures driving safety.

Other advantages, objects and features of the present invention will be set forth in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the investigation and research below, or can be obtained from It is taught in the practice of the present invention. The objects and other advantages of the invention will be realized and attained by the following description and claims.

Description of drawings

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with the accompanying drawings, wherein:

Figure 1 is a schematic diagram of the selection of the braking law during the running of the vehicle;

Fig. 2 is the flowchart of the shifting method under the mechanical automatic transmission braking situation of the present invention;

Fig. 3 is a schematic diagram of a method for determining a target gear position for a brake skip downshift of a mechanical automatic transmission.

Detailed ways

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be understood that the preferred embodiments are only for illustrating the present invention, but not for limiting the protection scope of the present invention.

The electronically controlled mechanical automatic transmission is based on the dry clutch and the fixed shaft gear stepped mechanical transmission with an electronic control system. The control of the accelerator, clutch and gear lever is driven by an electric motor or hydraulically. Thereby realizing the automatic control of gear selection and shifting, making the car an automatic shifting car. The present invention is applied to the shifting operation under the braking condition of the electromechanical automatic transmission. At first, as shown in Figure 1, the traveling vehicle first judges whether there is a braking signal, and if there is no braking, the traditional shifting rule is executed; If there is braking, the brake shifting rule is executed instead, and the braking shifting rule is shown in Figure 2, including the following steps:

Step A: The vehicle is running normally in the original gear. First, determine the engine speed. If the engine speed is greater than the engine idle speed, keep the original gear and drive normally. At this time, make full use of the braking force of the brake and the reverse torque of the engine for braking. Decelerate; if the engine speed is less than or equal to the idle speed, go to step B;

Step B: Determine the gear position of the transmission at this time. If the transmission is in the first gear, enter the vehicle start control process; if the transmission gear is greater than the first gear at this time, enter step C;

Step C: disengage the clutch, calculate the target gear according to the vehicle speed, and shift into the target gear after the brake is released. If there is always braking at this time, the clutch will always be disengaged, and the electronic control unit will always calculate the target gear until the brake is released;

Step D: Engage clutch; shift complete.

Below in conjunction with accompanying drawing 3 illustrates the method for determining the target gear when the mechanical automatic transmission of 12 gears jumps and downshifts.

(

)是当机械式自动变速器处于i挡且发动机转速为怠速转速时车辆所对应的车速，V为车辆当前车速，i为车辆当前挡位，

为目标挡位。执行制动换挡规律时，首先判断当前车速V是否大于当前挡位i下的车速

。若当前车速V大于当前挡位i下的车速

，则目标挡位

等于当前挡位i；若当前车速V小于等于当前挡位i下的车速

，则进一步判断当前挡位i是否大于等于2。若当前挡位i大于等于2，则i自动减1，回到开始继续判断车辆当前车速V是否大于

，依次类推，直至计算出目标挡位

；若当前挡位i小于2，直接判定目标挡位

等于1。在整个制动过程中，随着车速的降低不断执行该换挡规律，直至制动解除。最后机械式自动变速器换入目标挡位，接合离合器，完成换挡。 When the vehicle brakes while driving, the mechanical automatic transmission executes the brake shift schedule.

(

) is the vehicle speed corresponding to the vehicle when the mechanical automatic transmission is in gear i and the engine speed is at idle speed, V is the current speed of the vehicle, i is the current gear of the vehicle,

gear for the target. When executing the brake shift schedule, first judge whether the current vehicle speed V is greater than the vehicle speed in the current gear i

. If the current vehicle speed V is greater than the vehicle speed in the current gear i

, then the target gear

Equal to the current gear i; if the current vehicle speed V is less than or equal to the vehicle speed in the current gear i

, it is further judged whether the current gear i is greater than or equal to 2. If the current gear i is greater than or equal to 2, then i will be automatically decremented by 1, and return to the beginning to continue to judge whether the current speed V of the vehicle is greater than or equal to

, and so on, until the target gear is calculated

; If the current gear i is less than 2, directly determine the target gear

is equal to 1. During the entire braking process, the shifting schedule is continuously executed as the vehicle speed decreases until the brake is released. Finally, the mechanical automatic transmission shifts into the target gear, engages the clutch, and completes the shift.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements, without departing from the spirit and scope of the technical solution, should be included in the scope of the claims of the present invention.

Claims (1)

1. automatic mechanical transmission is realized the method for crash change of speed under the braking situation; Said automatic mechanical transmission is to have on the basis of grade mechanical transmission at dry clutch and fixed axis gear formula; Install ECU and automatic executing agency additional and obtain; It is characterized in that: judge through ECU to have or not brake signal,, carry out traditional schedule if there is not brake signal; If there is brake signal, then carry out the braking schedule, said braking schedule may further comprise the steps:

Steps A: vehicle is with former gear cruising, and ECU obtains engine speed through the CAN bus, if engine speed keeps former gear cruising greater than the engine idle rotating speed at this moment; If engine speed smaller or equal to idling speed, gets into step B;

Step B: ECU is judged transmission gear this moment, if speed changer is in a retaining, gets into the vehicle start control flow; If this moment, transmission gear kept off greater than one, get into step C;

Step C: cut-off clutch, ECU calculates the target gear according to the speed of a motor vehicle, changes to the target gear after the releasing to be braked;

Step D: engaging clutch, gearshift is accomplished.

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