A small-step heavy commercial vehicle transmission and its design method

Abstract

The present invention relates to a small-step heavy-duty commercial vehicle transmission and a design method thereof. The transmission is designed based on the research on vehicle operating conditions and standard interpretation in the tractor / truck market segment, and in combination with the physical characteristics and fuel consumption characteristics of heavy-duty diesel engines. The optimal fuel consumption and emission working area of the engine operating speed and load area are determined mainly through the urban, highway and high-speed cycles corresponding to the tractor / truck in the C-WTVC cycle curve. On the premise of ensuring the customer's power (without changing the total speed ratio, etc.) and user usage habits (driving and shifting habits), a 13-speed small-step transmission design scheme with a 7×2 layout structure for tractor / trucks is formulated. After the vehicle powertrain is matched, the engine speed of the tractor / truck can be effectively concentrated in the optimal working area during operation, achieving the purpose of fuel saving and emission reduction. At the same time, the ball stop area of the transmission control handle is redesigned to ensure the driving experience.

Description

Technical Field

[0001] The present invention belongs to the technical field of automotive powertrains, and particularly relates to a small-step heavy commercial vehicle transmission and its design method. Background Art

[0002] The design of heavy commercial vehicle transmissions generally refers to the development and matching design of transmissions based on vehicle power matching, ultimately achieving the optimization of vehicle power performance, fuel economy, emission pollutants, etc.

[0003] In recent years, relevant policies and regulations in the heavy truck industry have been intensively issued. The energy-saving technology and emission upgrade of heavy trucks have accelerated. The fuel consumption limit and emission regulations have affected the vehicle power matching towards energy conservation and low emissions. The third phase of GB30510-2018 issued by the Ministry of Industry and Information Technology requires that the fuel consumption limit be reduced by 15% - 18% on average compared with the second phase, and the main pollutants in the sixth stage of GB17691 are reduced by more than 75% compared with the fifth stage, putting forward new requirements for energy-saving and emission-reduction technologies and the design and matching of vehicle powertrains.

[0004] For some existing models in the heavy truck industry, it is necessary to define and develop the transmission ratio according to the working conditions. After a series of simulations and verifications, on the premise of ensuring power performance, it meets the requirements of regulatory certification and achieves fuel saving and emission reduction. Summary of the Invention

[0005] The present invention provides a small-step heavy commercial vehicle transmission, which is easy for users to operate, can efficiently reduce fuel consumption and emissions, meets the requirements of regulatory certification on the premise of ensuring power performance, achieves fuel saving and emission reduction, brings economic benefits to users, and can meet the national VI emission standards.

[0006] In order to solve the problems in the above background art, the present invention is realized through the following technical solutions:

[0007] A small-step heavy commercial vehicle transmission includes a 12-speed transmission. The first-gear ratio of the 12-speed transmission remains unchanged, the ratios and steps of gears from 2nd to 12th are reduced, and one more gear is added to form a 13-speed transmission.

[0008] The 13-speed transmission is arranged in a 7×2 structure. Its main box is provided with 7 pairs of forward gears, and its auxiliary box is provided with 2 sets of ratios, namely the low-speed area and the high-speed area.

[0009] As a further description of the invention: the first pair of forward gears in the main box of the 13-speed transmission is locked when in the high-speed area and can only be used in the low-speed area.

[0010] As a further illustration of the invention: The gear ranges of the 13-speed transmission are set to eight gears, with four gears symmetrically arranged in the upper and lower parts. Starting from the leftmost side in the upper part, they are: R1 / R2 gear, 1 / 7 gear, 3 / 9 gear, 5 / 11 gear; starting from the leftmost side in the lower part, they are: C gear, 2 / 8 gear, 4 / 10 gear, 6 / 12 gear, and an N gear is set between the 3 / 9 gear and the 4 / 10 gear.

[0011] As a further illustration of the invention: The gear ratio difference between the first gear and the second gear of the 13-speed transmission is 1.45 - 1.5, and a small gear ratio difference of 1.22 - 1.44 is adopted between the remaining gears.

[0012] As a further illustration of the invention: The 13-speed transmission includes two sets of gear ratios, namely the overdrive gear ratio and the direct drive gear ratio. The first gear ratio of the overdrive gear is 12.10, and the first gear ratio of the direct drive gear is 14.94.

[0013] On the premise of ensuring power performance (without changing the first gear ratio) and user usage habits (driving and shifting habits), the present invention combines the optimal fuel-saving and emission zones of the engine speed, and adjusts the gear ratio difference of the transmission for presetting. The present invention is realized through the following technical solutions:

[0014] A design method for a small-ratio difference heavy commercial vehicle transmission includes the following steps:

[0015] Step S1: Optimize the transmission gear ratio;

[0016] Step S2: Adjust the matching of the rear axle gear ratio;

[0017] Step S3: Set the gear ranges;

[0018] Step S4: Compare the simulation results.

[0019] The said step S1 includes the following steps:

[0020] Step S11: Meet the power matching for customer use;

[0021] Step S12: Control the engine operating speed at the working speed and load state of optimal fuel consumption and optimal emissions.

[0022] Compared with the prior art, the present invention has the following beneficial technical effects:

[0023] 1. The present invention is easy for users to operate, can efficiently reduce fuel consumption and emissions, meet the requirements of regulatory certification on the premise of ensuring power performance, achieve fuel saving and emission reduction, bring economic benefits to users, and can meet the national VI emission standards.

[0024] 2. The powertrain configuration of the present invention is optimized and analyzed for the configuration of existing vehicle models, which not only shortens the R & D time of transmission manufacturers but also meets the requirements of reducing fuel consumption and emissions, enhancing the competitiveness of vehicle manufacturers. Description of the Drawings

[0025] Figure 1 It is the C-WTVC cycle working condition diagram of a heavy commercial tractor / truck;

[0026] Figure 2 It is the layout diagram of the operating handle gear range of the 13-speed transmission in the present invention;

[0027] Figure 3 It is the schematic layout diagram of the 13-speed transmission in the present invention;

[0028] Figure 4 It is the distribution diagram of the engine landing points under the C-WTVC working condition of a tractor truck equipped with the original 12-speed transmission;

[0029] Figure 5 It is the distribution diagram of the engine landing points under the C-WTVC working condition of a tractor truck equipped with a 13-speed transmission..

[0030] Description of the Reference Numerals

[0031] 1. Main case; 2. Auxiliary case; 3. Input shaft; 4. Output shaft; 5. Intermediate shaft; 6. Countershaft; 7. C gear; 8. 1 / 7 gear; 9. 2 / 8 gear; 10. 3 / 9 gear; 11. 4 / 10 gear; 12. 5 / 11 gear; 13. 6 / 12 gear; 14. High gear range; 15. Low gear range. Detailed Embodiments

[0032] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention will be described in detail below with reference to the drawings and specific embodiments. It should be noted that, without conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

[0033] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention 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 of the present invention. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0034] In addition, terms such as "horizontal" and "vertical" do not mean that the components are required to be absolutely horizontal or hanging vertically, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0035] In the description of the present invention, it should also be noted that, unless otherwise clearly specified and defined, the terms "set", "installed", "connected", and "connected" 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 can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0036] As Figures 1 to 5 As shown, a small-step heavy commercial vehicle transmission includes a 12-speed transmission. The first-gear speed ratio of the 12-speed transmission remains unchanged, the speed ratios of the 2-12 gears and the step are reduced, and an additional gear is added to form a 13-speed transmission. The 13-speed transmission is arranged in a 7×2 structure. Its main case 1 is provided with 7 pairs of forward gears, and its auxiliary case 2 is provided with 2 sets of speed ratios, namely a low-speed range 15 and a high-speed range 14. The first pair of forward gears of the main case 1 of the 13-speed transmission is locked when in the high-speed range 14 and can only be used in the low-speed range 15.

[0037] Specifically, the gear ranges of the 13-speed transmission are set to eight gears, with four gears symmetrically arranged in the upper and lower parts. Starting from the leftmost side of the upper part, they are: R1 / R2 gear, 1 / 7 gear 8, 3 / 9 gear 10, 5 / 11 gear 12; starting from the leftmost side of the lower part, they are: C gear 7, 2 / 8 gear 9, 4 / 10 gear 11, 6 / 12 gear 13, and an N gear is set between the 3 / 9 gear 10 and the 4 / 10 gear 11.

[0038] The step between the first gear and the second gear of the 13-speed transmission is 1.45-1.5, and the small step of 1.22-1.44 is adopted between the remaining gears. The 13-speed transmission includes two sets of speed ratios, namely an overdrive gear and a direct gear. The first-gear speed ratio of the overdrive gear is 12.10, the speed ratio step of the 2-13 gears is reduced to 1.235, the sub-high gear is a direct gear (speed ratio is 1.0), the highest gear (the 13th gear) is an overdrive gear, the speed ratio is set to 0.81, and the step between the first gear and the second gear is 1.471; the first-gear speed ratio of the direct gear is 14.94, and the highest gear is a direct gear (speed ratio is 1.0).

[0039] This application also includes a design method for a small-step heavy commercial vehicle transmission, which further includes the following steps;

[0040] Step S1: Optimize the transmission ratio. On the premise of meeting the power matching for customer use, control the engine operating speed at the working speed and load state with optimal fuel consumption and optimal emissions. According to the GB27840 C-WTVC cycle curve (see Figure 1 ), for the highway cycle and high-speed cycle corresponding to the towing vehicle, when the vehicle speed is 0 - 88 km / h, the main engine working speed range is n ± 150 rpm;

[0041] Step S2: Adjust the matching of the rear axle ratio. The engine working speed range is reduced by 50 rpm to become n ± 125 rpm ( Figure 5 ), which is more concentrated in the optimal engine working area and is beneficial to reducing fuel consumption;

[0042] Step S3: Set the gear range;

[0043] Step S4: Compare the simulation results. Based on the AVL CRUISE software, establish a new power matching under the same vehicle type and regulatory comprehensive working conditions, and compare it with the simulation results and test results of the original configuration.

[0044] The embodiments given above are the preferred examples for implementing the present invention, and the present invention is not limited to the above embodiments. Any non-essential addition or replacement made by those skilled in the art based on the technical features of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A small-step heavy commercial vehicle transmission, including a 12-speed transmission, characterized in that: The first-gear speed ratio of the 12-speed transmission remains unchanged, the speed ratios and step ratios of gears 2-12 are reduced, and one more gear is added to form a 13-speed transmission; the 13-speed transmission is arranged in a 7x2 structure, with 7 pairs of forward gears in its main box and 2 sets of speed ratios in its auxiliary box, namely the low-speed range and the high-speed range; When the first pair of forward gears in the main box of the 13-speed transmission is in the high-speed range, it is locked and can only be used in the low-speed range; The gear range of the 13-speed transmission is set to eight gears, with four gears symmetrically arranged in the upper and lower parts. Starting from the leftmost in the upper part, they are: R1 / R2, 1 / 7, 3 / 9, 5 / 11; starting from the leftmost in the lower part, they are: C, 2 / 8, 4 / 10, 6 / 12, and N is set between 3 / 9 and 4 / 10; The step ratio between the first gear and the second gear of the 13-speed transmission is 1.45-1.5, and a small step ratio of 1.22-1.44 is adopted between the remaining gears; The 13-speed transmission includes two sets of speed ratios, an overdrive and a direct drive. The first-gear speed ratio of the overdrive is 12.10, and the first-gear speed ratio of the direct drive is 14.

94.

2. A design method for a small-step heavy commercial vehicle transmission, including the small-step heavy commercial vehicle transmission as described in claim 1, characterized in that: It includes the following steps: Step S1: Optimize the transmission speed ratio; Step S2: Adjust the matching of the rear axle speed ratio; Step S3: Set the gear range; Step S4: Compare the simulation results.

3. A design method for a small-step heavy commercial vehicle transmission according to claim 2, characterized in that: Step S1 includes the following steps: Step S11: Meet the power matching for customer use; Step S12: Control the engine operating speed at the working speed and load state of optimal fuel consumption and optimal emissions.

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