AMT-based national sixth NGE exhaust braking upshift synchronous speed reduction control system and method

Abstract

The invention provides a national sixth NGE exhaust braking upshift synchronous speed reduction control system and method based on an AMT. The system comprises a natural gas engine, and an output shaft of the natural gas engine is connected with an input shaft of the AMT through a clutch; a gas inlet pipe and an exhaust pipe are arranged on the natural gas engine, a tail gas processor is installed on the exhaust pipe, and an exhaust brake valve is arranged on the exhaust pipe between the natural gas engine and the tail gas processor. An ECU is arranged on the natural gas engine, a TCU is arranged on the AMT, and the exhaust brake valve is controlled through the TCU. And the exhaust brake valve is connected with the TCU through a hard wire. According to the method, in the shifting synchronization stage of the commercial vehicle AMT matched with the natural gas engine, the AMT utilizes and controls exhaust braking to rapidly reduce the rotating speed of the engine within a short time, so that the AMT rapidly completes shifting clutch control.

Description

Technical Field

[0001] The present invention belongs to the technical field of engines and relates to a natural gas engine, and in particular to a National VI NGE exhaust brake upshift synchronous speed reduction control system and method based on AMT. Background Art

[0002] Commercial vehicle AMT (Automated Mechanical Transmission) has been launched in large quantities in the Chinese market by 2024, with cumulative domestic sales exceeding 100,000 units. The main matching commercial vehicle engines include diesel engines, NGE (Natural Gas Engine), oil-gas hybrid engines, and methanol engines. Diesel engines have been matched with AMT and put on the market in large quantities since 2019. Since 2022, the continuous rise in diesel prices and the continuous decline in natural gas prices have caused the price difference between the two to be nearly doubled, which directly led to the sales of commercial vehicle AMTs matching diesel engines continuing to decline since 2022, and the sales of commercial vehicle AMTs matching natural gas engines continuing to rise. In 2023 and 2024, natural gas AMT commercial vehicles sold by domestic commercial vehicle manufacturers accounted for more than 70% of the total AMT sales.

[0003] Due to the low diesel price abroad, natural gas engines have not become mainstream competitiveness, and foreign AMTs are rarely matched with natural gas engines. There is not much experience in matching commercial vehicle natural gas engines abroad to learn from. China will also become a pioneer in AMT matching in the commercial vehicle market. In the past three years, many problems have been encountered in the matching of AMT with natural gas engines. Among them, the most important characteristics of commercial vehicle natural gas engines are large torque response delay, poor torque accuracy, and slow torque response. It becomes extremely difficult for external controllers such as TCU to control engine torque and speed. Starting from the problem of matching natural gas engines in the AMT upshift synchronization stage, this patent proposes a control solution that quickly reduces the speed of the natural gas engine in the AMT upshift synchronization stage to increase the shift speed and shorten the shift power interruption time.

[0004] In the earliest domestic National III and National IV diesel electronic control engine stage, exhaust braking was partially used. In the National V stage, most of it was replaced by in-cylinder braking. Only a few diesel engine models retained exhaust braking. In the National VI diesel engine stage, exhaust braking was almost completely replaced by in-cylinder braking due to post-processing layout reasons. However, for natural gas engines, since the post-processing structure is relatively simple, it is easier to arrange exhaust brake valves. Due to the significant characteristics of natural gas engines matched with AMT, the ECU uses a continuous air control solution, which leads to slow engine deceleration, resulting in large AMT shifting delays and power interruptions, which is also one of the main problems causing poor comfort and large shifting delays in domestic natural gas-matched AMT automatic transmissions.

[0005] Due to the technical characteristics of commercial vehicle natural gas engines, factors such as small compression ratio, low calorific value and slow combustion speed determine that the transient torque response of natural gas engines is slower than that of diesel engines. In order to overcome the delay in torque transient response, some commercial vehicle natural gas engine types currently use a continuous gas solution to deal with the torque response delay problem during the AMT synchronous shifting process. This can effectively improve the torque response speed after synchronization is completed, but the disadvantages and problems it brings are also very obvious. That is, continuous gas cannot accurately predict the accuracy deviation of the torque with the friction torque accessory torque, and continuous gas may become a positive torque output. The result is a decrease in engine speed, a slowdown, and even the inability to reduce to the target engine speed for a long time. This has also become a technical difficulty for commercial vehicle natural gas engines to overcome and solve. Summary of the invention

[0006] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a National VI NGE exhaust brake upshift and synchronous speed reduction control system and method based on AMT, so as to solve the technical problem in the prior art that the shifting time needs to be further shortened due to the lack of air in the control system.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0008] A natural gas engine exhaust brake upshift synchronous speed reduction control system based on AMT, the system includes a natural gas engine, the output shaft of the natural gas engine is connected to the input shaft of the AMT through a clutch; the natural gas engine is provided with an intake pipe and an exhaust pipe, and an exhaust gas processor is installed on the exhaust pipe.

[0009] An exhaust brake valve is arranged on the exhaust pipe between the natural gas engine and the exhaust gas processor.

[0010] The present invention also has the following technical features:

[0011] The natural gas engine is provided with an ECU, the AMT is provided with a TCU, and the exhaust brake valve is controlled by the TCU.

[0012] The exhaust brake valve is connected to the TCU via a hard line.

[0013] The natural gas engine adopts the National VI natural gas engine.

[0014] The present invention also protects a natural gas engine exhaust brake upshift synchronous speed reduction control method based on AMT, which adopts the natural gas engine exhaust brake upshift synchronous speed reduction control system based on AMT as described above.

[0015] In this method, the method in which the TCU controls the exhaust brake valve is:

[0016] In the first step, the TCU calculates the speed difference △N between the engine speed N1 and the input shaft speed N2 during the synchronization process, that is, △N=N1-N2, and corrects the slope S1 of the target engine speed according to the size of the speed difference △N, so that when the engine speed is about to reach the target input shaft speed △N≤50rpm, the exhaust brake can release the braking force of the exhaust brake in advance. The TCU controls the opening and closing of the exhaust brake valve through hard wire, and the response delay of the exhaust brake valve is 100ms~200ms on average.

[0017] In the second step, TCU controls the braking torque of the exhaust brake by performing PID closed-loop control calculation through the decrease rate deviation value S between the actual engine speed S2 and the target engine speed S1, that is, S=S2-S1. The result of the closed-loop control is that the size of the braking torque of the exhaust brake controls the speed of the engine speed decrease slope S3.

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

[0019] (I) The present invention provides a commercial vehicle AMT matched with a natural gas engine shift synchronization stage, the AMT uses and controls exhaust braking to quickly reduce the engine speed in a short time, so that the AMT can quickly complete the shift clutch control.

[0020] (II) The system of the present invention installs an exhaust brake butterfly valve mechanism at the front end of the after-treatment of the natural gas engine exhaust pipe. The exhaust brake butterfly valve mechanism is installed at the front end of the after-treatment in order to effectively protect the exhaust gas processor from the influence of the exhaust brake operation. The exhaust brake butterfly valve mechanism is hard-wired to the control unit TCU of the AMT gearbox. The exhaust brake butterfly valve is directly controlled by the TCU to control the opening and closing control force. Therefore, in the upshift synchronization stage, the exhaust brake is used to quickly reduce the engine speed of the natural gas engine when the gas is not cut off, and the speed reduction slope is increased, so that the AMT can quickly complete the clutch synchronous shifting, effectively shorten the shift synchronization time, improve the shift comfort, and reduce the driver's sense of power interruption during shifting.

[0021] (III) Usually, the exhaust brake is connected to the engine ECU to directly accept the control of the engine ECU. However, the biggest disadvantage of this is that the response delay of the exhaust brake controlled by the TCU is greatly increased. Especially in natural gas engines, the torque response hysteresis will bring greater control delay. Therefore, the present invention chooses to connect the exhaust brake directly to the transmission controller TCU for direct control, which can improve the response speed and achieve the control purpose. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the exhaust brake upshift and synchronous speed reduction control system of the natural gas engine based on AMT.

[0023] Figure 2 This is a schematic diagram of the working principle of the engine ECU and the AMT's TCU exchanging information through the bus, and the TCU controlling the exhaust brake through a hard-wired connection.

[0024] Figure 3 It is a schematic diagram of the entire process of AMT automatic transmission upshifting and the stages of TCU controlling exhaust brake intervention. State represents the gear shift synchronization state.

[0025] Figure 4 The control logic and calculation method for the exhaust brake inside the TCU to quickly reduce the engine speed.

[0026] Figure 5 It is a schematic diagram of the slower speed drop slope caused by the continuous gas supply of the natural gas engine, the normal engine speed drop slope, the engine speed drop slope after the TCU controls the exhaust brake to assist in increasing the speed drop slope, and the entire AMT upshift synchronization process.

[0027] The meanings of the numbers in the figure are: 1-natural gas engine, 2-clutch, 3-AMT, 4-intake pipe, 5-exhaust pipe, 6-exhaust gas processor, 7-exhaust brake valve, 8-ECU, 9-TCU, 10-hard line.

[0028] The specific contents of the present invention are further explained in detail below in conjunction with embodiments. DETAILED DESCRIPTION

[0029] It should be noted that, unless otherwise specified, all devices and components in the present invention are devices and components known in the prior art.

[0030] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0031] Example:

[0032] This embodiment provides a natural gas engine exhaust brake upshift synchronous speed reduction control system based on AMT, such as Figure 1 As shown, the system includes a natural gas engine 1, the output shaft of the natural gas engine 1 is connected to the input shaft of the AMT 3 through a clutch 2; an intake pipe 4 and an exhaust pipe 5 are provided on the natural gas engine 1, and an exhaust gas processor 6 is installed on the exhaust pipe 5.

[0033] like Figure 1 As shown, an exhaust brake valve 7 is provided on the exhaust pipe 5 between the natural gas engine 1 and the exhaust gas processor 6 .

[0034] Further, such as Figure 1 As shown, the natural gas engine 1 is provided with an ECU (Electronic Control Unit) 8 , the AMT 3 is provided with a TCU (Telematics Control Unit) 9 , and the exhaust brake valve 7 is controlled by the TCU 9 .

[0035] As a preferred solution of this embodiment, Figure 1 As shown, the exhaust brake valve 7 and the TCU 9 are connected via a hard line 10 .

[0036] As a preferred solution of this embodiment, Figure 1 As shown, the natural gas engine 1 adopts the National VI natural gas engine.

[0037] The working process of the exhaust brake upshift synchronous speed reduction control system of the natural gas engine based on AMT of this embodiment is as follows: Figure 2As shown, the exhaust brake valve 7 is directly controlled by TCU9, and TCU9 and ECU8 of the natural gas engine 1 exchange information through the CAN bus. At the same time, TCU9 obtains the speed N2 information of the input shaft of AMT3 through the input shaft speed sensor, and obtains the engine speed N1 information of the natural gas engine 1 through the CAN line, which is calculated and used in the synchronous exhaust brake control process.

[0038] Embodiment 2:

[0039] This embodiment provides a natural gas engine exhaust brake upshift synchronous speed reduction control method based on AMT. The method adopts the natural gas engine exhaust brake upshift synchronous speed reduction control system based on AMT provided in Example 1.

[0040] In this method, Figure 3 As shown, the entire upshift process of AMT3 is:

[0041] The first step is to enter State = 1 stage. The upshift conditions are met, AMT3 makes an upshift request, and TCU9 sends a target gear position to enter this stage.

[0042] The second step is to enter the State=2 stage, where TCU9 unloads the torque of the natural gas engine 1 through torque-related control, and releases the clutch 2 after the engine torque is cleared to 0. The second stage is completed after the clutch 2 is completely released.

[0043] The third step is to enter the State=3 stage. After the clutch 2 is completely separated, it officially enters the gear shift synchronization stage. First, the gear selection and shifting operation of the target gear is completed. In the speed synchronization stage, TCU9 controls the opening and closing of the exhaust brake valve 7, and TCU9 controls the braking torque, thereby controlling the speed reduction slope of the natural gas engine 1. This stage is completed.

[0044] The fourth step is to enter the State=4 stage. When the speed of the natural gas engine 1 drops to a certain range with the speed difference of the input shaft speed of the AMT3, the clutch 2 is synchronously controlled, and the clutch 2 is controlled from semi-clutch to full-clutch, and this stage is completed.

[0045] The fifth step is to enter State = 5 stage, return the torque of the natural gas engine 1 to the driver's accelerator pedal torque, and the entire AMT3 upshift process is completed. TCU9 controls the exhaust brake valve 7 to intervene and work in the gear shift synchronization stage to quickly meet the speed difference requirements and complete the synchronization stage to shorten the speed control time, thereby speeding up the entire gear shift process.

[0046] In this method, Figure 4 and Figure 5 As shown, the method of TCU9 controlling the exhaust brake valve 7 is:

[0047] In the first step, TCU9 calculates the speed difference △N between the engine speed N1 and the input shaft speed N2 during the synchronization process, that is, △N=N1-N2, and corrects the slope S1 of the target engine speed according to the size of the speed difference △N, so that when the engine speed is about to reach the target input shaft speed △N≤50rpm, the exhaust brake can release the braking force of the exhaust brake in advance. TCU9 controls the opening and closing of the exhaust brake valve 7 through the hard line 10, and the response delay of the exhaust brake valve 7 is 100ms~200ms on average.

[0048] In this step, in order to prevent the residual exhaust brake torque when the clutch 2 is synchronized, if there is a large residual exhaust brake torque during the synchronization stage of the clutch 2, the instantaneous switching of the positive and negative torques of the natural gas engine 1 will cause the transmission system torsional vibration, which is not conducive to the comfort of gear shifting.

[0049] In the second step, TCU9 controls the braking torque of the exhaust brake by performing PID closed-loop control calculation through the decrease rate deviation value S between the actual engine speed S2 and the target engine speed S1, that is, S=S2-S1. The result of the closed-loop control is that the size of the braking torque of the exhaust brake controls the speed of the engine speed decrease slope S3.

[0050] In this step, through repeated closed-loop control, the goal of TCU9 quickly reducing the engine speed through exhaust braking is finally achieved, thus solving the problem of slow engine speed reduction due to continuous gas supply during the synchronization process of the natural gas engine.

Claims

1. A natural gas engine exhaust brake upshift synchronous speed reduction control system based on AMT, the system comprising a natural gas engine (1), the output shaft of the natural gas engine (1) is connected to the input shaft of the AMT (3) through a clutch (2); the natural gas engine (1) is provided with an intake pipe (4) and an exhaust pipe (5), and the exhaust pipe (5) is installed with an exhaust gas processor (6), characterized in that: An exhaust brake valve (7) is provided on the exhaust pipe (5) between the natural gas engine (1) and the exhaust gas processor (6).

2. The exhaust brake upshift synchronous deceleration control system for a natural gas engine based on an AMT as claimed in claim 1, wherein the natural gas engine (1) is provided with an ECU (8), and the AMT (3) is provided with a TCU (9), characterized in that: The exhaust brake valve (7) is controlled by a TCU (9).

3. The exhaust brake upshift synchronous speed reduction control system for a natural gas engine based on an AMT as claimed in claim 2, characterized in that: The exhaust brake valve (7) and the TCU (9) are connected via a hard line (10).

4. The exhaust brake upshift synchronous speed reduction control system for a natural gas engine based on an AMT as claimed in claim 1, characterized in that: The natural gas engine (1) adopts a National VI natural gas engine.

5. A natural gas engine exhaust brake upshift synchronous speed reduction control method based on AMT, characterized in that: The method adopts the AMT-based natural gas engine exhaust brake upshift synchronous speed reduction control system as described in any one of claims 1 to 4.

6. The AMT-based natural gas engine exhaust brake upshift synchronous speed reduction control method according to claim 5, characterized in that: In the method, the TCU (9) controls the exhaust brake valve (7) in the following manner: In the first step, the TCU (9) calculates the speed difference ΔN between the engine speed N1 and the input shaft speed N2 during the synchronization process, i.e., ΔN=N1-N2, and corrects the slope S1 of the target engine speed according to the speed difference ΔN, so that when the engine speed is about to reach the target input shaft speed ΔN≤50rpm, the exhaust brake can release the exhaust brake force in advance. The TCU (9) controls the opening and closing of the exhaust brake valve (7) through the hard line (10), and the response delay of the exhaust brake valve (7) is 100ms to 200ms on average. In the second step, the TCU (9) controls the braking torque of the exhaust brake by performing a PID closed-loop control calculation through a decrease rate deviation value S between the actual engine speed S2 and the target engine speed S1, i.e., S=S2-S1. The result of the closed-loop control is that the magnitude of the braking torque of the exhaust brake controls the speed of the engine speed decrease slope S3.

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