CROSS REFERENCE TO THE RELATED APPLICATIONS

This application is the national phase entry of International Application No. PCT/CN2020/106688, filed on Aug. 4, 2020, which is based upon and claims priority to Chinese Patent Application No. 202010697629.1, filed on Jul. 20, 2020, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to the field of vehicle gearboxes, and in particular, to a power-split hydro-mechanical hybrid transmission system with an automatic adjustment function.

BACKGROUND

The hydro-mechanical hybrid transmission adopts hydraulic transmission for startup, hydro-mechanical transmission for operation, and mechanical transmission for transfer to adapt to different working conditions. The hydro-mechanical transmission is mainly divided into two modes: power split and power convergence. The power split mode is implemented by arranging a 2K-H planetary gear mechanism on the front side and is mainly suitable for low-power transmission systems, while the power convergence mode is implemented by arranging a 2K-H planetary gear mechanism on the rear side and is mainly suitable for high-power transmission systems.

The conventional hydraulic speed regulation is mainly implemented by volume, that is, the displacement of a variable displacement pump is controlled for speed regulation. It is difficult for an engine serving as a power source to meet the requirements on both power and fuel economy; and if a motor is adopted for speed regulation, it is difficult to meet the requirements on traction power of the high-power transmission system typically adopting the power convergence mode, while it is one of the feasible solutions to improve the performance of the low-power transmission system typically adopting the power split mode.

The current research mainly focuses on the safe and reliable performance and the energy conservation and emission reduction characteristics of vehicle transmission systems, but only a few applications are made in terms of hydro-mechanical hybrid transmission. A hydraulic transmission mechanism taking safety, reliability, and energy utilization into account can greatly improve the performance of the hydro-mechanical hybrid transmission system.

SUMMARY

To eliminate the defects in the prior art, the present invention provides a power-split hydro-mechanical hybrid transmission system with an automatic adjustment function, which enables multi-mode continuously variable transmission and has energy reuse and emergency support functions.

The present invention achieves the above objective through the following technical solution.

A power-split hydro-mechanical hybrid transmission system with an automatic adjustment function includes an input member, a hydraulic transmission mechanism, a split mechanism, a convergence mechanism, an output member, a clutch assembly, and a brake assembly, wherein the clutch assembly connects the input member to an input end of the split mechanism, connects an output end of the split mechanism to an input end of the hydraulic transmission mechanism and an input end of the convergence mechanism, and connects an output end of the hydraulic transmission mechanism to the output member; an output end of the convergence mechanism is connected to the output member; and the clutch assembly and the brake assembly provide a continuous transmission ratio between the input member and the output member.

Further, transmission modes including hydraulic transmission, hydro-mechanical transmission, and mechanical transmission are provided between the input member and the output member by adjusting a displacement ratio of the hydraulic transmission mechanism and selectively controlling engagement of the clutch assembly and the brake assembly.

Further, the split mechanism includes a split mechanism-ring gear, a split mechanism-planet carrier, and a split mechanism-sun gear, wherein the split mechanism-ring gear is connected to the input member;

the convergence mechanism includes a convergence mechanism-common ring gear, a convergence mechanism-small sun gear, a convergence mechanism-large sun gear, a convergence mechanism-short planet carrier, and a convergence mechanism-long planet carrier, wherein the convergence mechanism-short planet carrier is connected to the convergence mechanism-long planet carrier, and the convergence mechanism-long planet carrier is connected to the output member; the convergence mechanism-common ring gear, the convergence mechanism-small sun gear, and the convergence mechanism-short planet carrier form a planetary gear train, while the convergence mechanism-common ring gear, the convergence mechanism-large sun gear, and the convergence mechanism-long planet carrier form another planetary gear train;

the clutch assembly includes a clutch C1and a clutch C2, wherein the clutch C1is used for selectively connecting the split mechanism-sun gear to the input end of the hydraulic transmission mechanism to achieve synchronous rotation, and the clutch C2is used for selectively connecting the output end of the hydraulic transmission mechanism to the output member to achieve synchronous rotation; the brake assembly includes a brake B1, wherein the brake B1is used for selectively connecting the split mechanism-planet carrier to a fixed member;

the clutch C1, the clutch C2, and the brake B1are engaged to provide forward or reverse hydraulic transmission between the input member and the output member.

Further, the clutch assembly further includes a clutch C3, a clutch C4, and a clutch C5, wherein the clutch C3is used for selectively connecting the split mechanism-planet carrier to the convergence mechanism-large sun gear to achieve synchronous rotation, the clutch C4is used for selectively connecting the convergence mechanism-small sun gear to the convergence mechanism-large sun gear to achieve synchronous rotation, and the clutch C5is used for selectively connecting the split mechanism-ring gear to the split mechanism-planet carrier to achieve synchronous rotation; the brake assembly further includes a brake B2and a brake B3, wherein the brake B2is used for selectively connecting the convergence mechanism-small sun gear to a fixed member, and the brake B3is used for selectively connecting the convergence mechanism-common ring gear to a fixed member;

the clutch C3, the clutch C5, and the brake B3are engaged to provide reverse mechanical transmission between the input member and the output member; the clutch C3, the clutch C5, and the brake B2are engaged or the clutch C3, the clutch C4, and the clutch C5are engaged to provide different forward mechanical transmissions between the input member and the output member.

Further, the clutch C1, the clutch C2, the clutch C3, and the brake B3are engaged to provide reverse hydro-mechanical transmission between the input member and the output member;

the clutch C1, the clutch C2, the clutch C3, and the brake B2are engaged or the clutch C1, the clutch C2, the clutch C3, and the clutch C4are engaged to provide different forward hydro-mechanical transmissions between the input member and the output member.

Further, the hydraulic transmission mechanism includes a variable displacement pump, an oil replenishing system, a solenoid directional valve V3, a proportional throttle valve V8, a safety valve group, a three-position four-way proportional directional valve V9, a high-pressure accumulator A1, a low-pressure accumulator A2, an emergency valve V10, and a pump/motor mechanism, wherein an input end of the variable displacement pump is connected to the output end of the split mechanism through the clutch C1, an output end of the pump/motor mechanism is connected to the output member through the clutch C2, the variable displacement pump is used for driving the pump/motor mechanism, the solenoid directional valve V3for one-way flow of oil is disposed on a high-pressure hydraulic pipe between an oil outlet of the variable displacement pump and an oil inlet of the pump/motor mechanism; the proportional throttle valve V8is disposed on a low-pressure hydraulic pipe between an oil inlet of the variable displacement pump and an oil outlet of the pump/motor mechanism; the proportional directional valve V9is connected in parallel between the low-pressure hydraulic pipe and the high-pressure hydraulic pipe; the high-pressure accumulator A1and the low-pressure accumulator A2are both connected to the proportional directional valve V9;

the low-pressure hydraulic pipe and the high-pressure hydraulic pipe share the safety valve group for pressure adjustment of the pipes; the oil replenishing system is used for replenishing hydraulic oil in the low-pressure hydraulic pipe and/or the high-pressure hydraulic pipe.

Further, when the output member decelerates, the clutch C2is engaged, and braking energy of the output member is transmitted to the pump/motor mechanism; the pump/motor mechanism works as a hydraulic pump; the solenoid directional valve V3is controlled to be powered on, preventing the oil from flowing back to the variable displacement pump; the proportional throttle valve V8is controlled to reduce port opening, thereby increasing pressure at the oil outlet of the pump/motor mechanism; the proportional directional valve V9is controlled to make the low-pressure accumulator A2communicated with the oil inlet of the pump/motor mechanism to replenish oil; and the proportional directional valve V9is controlled to make the high-pressure accumulator A1communicated with the oil outlet of the pump/motor mechanism to store energy.

Further, when the output member accelerates, the pump/motor mechanism works as a hydraulic pump; the solenoid directional valve V3is controlled to be powered on, preventing the oil from flowing back to the variable displacement pump; the proportional directional valve V9is controlled to make the low-pressure accumulator A2communicated with the oil outlet of the pump/motor mechanism; the proportional directional valve V9is controlled to make the high-pressure accumulator A1communicated with the oil inlet of the pump/motor mechanism; the pump/motor mechanism is driven by the high-pressure accumulator A1alone or by both the high-pressure accumulator A1and the variable displacement pump; and the low-pressure accumulator A2is used for recovering residual energy.

Further, the emergency valve V10is further connected in parallel between the low-pressure hydraulic pipe and the high-pressure hydraulic pipe; the emergency valve V10is controlled to cut off power transmitted from the variable displacement pump, or switch power to be stored by the pump/motor mechanism, or release power stored in the high-pressure accumulator A1and the low-pressure accumulator A2.

The present invention has the following beneficial effects:

1. The power-split hydro-mechanical hybrid transmission system with an automatic adjustment function of the present invention adopts hydraulic transmission, hydro-mechanical transmission, and mechanical transmission to adapt to different working conditions.

2. According to the power-split hydro-mechanical hybrid transmission system with an automatic adjustment function of the present invention, the displacement of the variable displacement pump is controlled to adjust the displacement ratio of the hydraulic transmission mechanism, a frequency converter is controlled to regulate the motor speed, and the corresponding clutch assembly and brake assembly are engaged or disengaged to improve various transmission modes in forward and reverse gears.

3. According to the power-split hydro-mechanical hybrid transmission system with an automatic adjustment function of the present invention, the main power source consisting of various types of valves, the frequency converter, and the motor, the auxiliary power source consisting of the accumulators, and the variable displacement pump are combined to provide a highly reliable and multi-degree-of-freedom transmission system.

