CN101654060A - Mechanic and hydraulic hybrid type power transmission system and control method - Google Patents

Abstract

The invention relates to a machine-hydraulic hybrid power transmission system and a control method. The transmission system is characterized in that a hydraulic pump/motor (12) is rigidly connected between the internal combustion engine (2) and the clutch (11), and the high-pressure oil port of the hydraulic pump/motor (12) is connected with the two-position three-way valve A (4) , and is connected with the high-pressure accumulator (5) through the hydraulic control check valve (7); the low-pressure oil port of the hydraulic pump/motor (12) is connected with the low-pressure accumulator (13); the hydraulic pump/motor (12) also The two-position three-way valve B (8) is connected to the hydraulic control check valve (7); the pressure sensor (6) of the high-pressure accumulator (5), the brake pedal position sensor (15), the accelerator pedal position sensor (16 ) and the internal combustion engine starter key position sensor (17) are connected to the hybrid power control unit (9) through cables; the hybrid power control unit (9) is connected to the hydraulic pump/motor (12) through the pump/motor displacement electro-hydraulic control device (14) . The device has the advantages of simple structure, convenient operation and low cost, and can be used for rebuilding existing vehicles or for new vehicles.

Description

A machine-hydraulic hybrid power transmission system and control method

technical field

The invention provides a machine-hydraulic hybrid power transmission system and a control method, and specifically relates to energy utilization, conversion and storage of motor vehicle power and transmission systems. The purpose of the invention is to realize the energy saving and emission reduction of motor vehicles.

Background technique

With the rapid growth of the number of motor vehicles, oil consumption is increasing year by year, and the tail gas emitted by motor vehicles has caused serious air pollution. Studies have shown that for vehicles powered by internal combustion engines, only 15-25% of the fuel energy is used to drive the vehicle, and the rest of the fuel energy is consumed by rolling resistance, wind resistance, acceleration, and braking during vehicle driving. In order to reduce energy consumption and emissions of motor vehicles, traditional methods include improving the efficiency of the internal combustion engine, improving the efficiency of the drive train, reducing the total weight of the vehicle, and adopting a body with low wind resistance. The above energy-saving measures for motor vehicles need to pay huge development and production costs, and even have to sacrifice the safety and driving performance of the vehicle. Hydrogen fuel cell vehicles have high energy utilization efficiency and zero emissions, and the long-term prospects are promising. Fuel cell vehicles cannot be commercialized in the near future. Battery-driven electric vehicles have high energy utilization efficiency and zero emissions, and the technology is relatively mature, but technical indicators such as battery cost, weight, energy density, power density, driving range, life, and charging time have not yet made significant progress. Under such circumstances, it is difficult to fully realize the industrialization of battery-driven electric vehicles and can only operate in specific areas. After years of research, the vehicle industry has reached a consensus that before oil resources are exhausted, vehicles driven by internal combustion engines will still be the mainstream, and zero-emission vehicles driven by hydrogen fuel cells and batteries are the ultimate goal. The emission reduction solution is the hybrid technology of internal combustion engine and battery. The internal combustion engine-battery-electric motor/generator deep hybrid system recovers vehicle braking energy through the generator, uses the electric motor to start and assist the internal combustion engine to accelerate, and keeps the internal combustion engine in a high-efficiency working area all the time. Compared with traditional pure gasoline vehicles, electromechanical hybrid vehicles save energy. The goal of oil 30-50% has become one of the most promising energy-saving technologies for vehicle power systems.

However, there are some disadvantages in the battery-generator braking energy recovery system adopted by the current electromechanical hybrid (internal combustion engine-battery-generator/electric motor) powered vehicle. Due to the inherent charging and discharging characteristics of the battery, its power density is low, and it is impossible to store or release a large amount of energy in a short time. Therefore, when the braking time of the vehicle is very short and the braking energy density is extremely high, it is difficult for the battery-generator type braking energy recovery system to effectively recover the huge kinetic energy generated at the moment of braking, resulting in low braking energy recovery efficiency. . However, vehicles such as buses and taxis that often operate in cities need to be started and braked frequently. The efficiency of internal combustion engines is extremely low, and the requirements for brakes are extremely high. It can be seen that the structure is simpler, the power density is higher, and the cost is lower. The hydraulic accumulator-hydraulic pump/motor braking energy recovery technology suitable for frequent braking and starting of vehicles has emerged as the times require. Since there is no mutual conversion between chemical energy and mechanical energy in the energy conversion process in the hydraulic accumulator-hydraulic pump/motor brake energy recovery system, its conversion speed is fast. In addition, due to the high power density of the accumulator, this enables the hydraulic accumulator-hydraulic pump/motor braking energy recovery system to recover braking energy more effectively and quickly. Therefore, the machine-hydraulic hybrid (internal combustion engine-hydraulic accumulator-hydraulic pump/motor) powered vehicle with a hydraulic accumulator-hydraulic pump/motor brake energy recovery system is another energy-saving vehicle suitable for driving in urban conditions. Environmentally friendly vehicles are attracting more and more attention.

Contents of the invention

The invention proposes a mechanical-hydraulic hybrid power transmission system and a control method aiming at the deficiencies in energy utilization and emission of traditional internal combustion engines and the complexity and high cost of electromechanical hybrid power systems. According to the actual operating conditions of the vehicle, the machine-hydraulic hybrid power transmission system of the present invention optimizes the operating conditions of the internal combustion engine, adopts the hydraulic pump/motor to recover braking energy, uses the hydraulic pump/motor to start the internal combustion engine and drives the vehicle, and adopts Controlled flameout of internal combustion engines and other technical means can achieve relatively large energy saving and emission reduction of motor vehicles.

The purpose of the present invention is to realize the optimization of the vehicle power system through the mixing of machine and fluid according to the load characteristics of the vehicle and the power characteristics of the internal combustion engine. The system is simple in structure, easy to modify, and easy to operate. Under the condition of ensuring the power and comfort of the vehicle, the internal combustion engine can often work in the high-efficiency and low-emission area, and can realize the shutdown of the internal combustion engine, the optimization of the working conditions of the internal combustion engine, and the recovery of braking energy. It is easy to retrofit by simply installing a hydraulic pump/motor before the vehicle clutch.

The core idea of the present invention is to adopt the hydraulic pump/motor to start the internal combustion engine and drive the vehicle to start. At low speed and low load, the internal combustion engine can save energy and reduce emissions by adopting internal combustion engine condition optimization, hydraulic pump/motor energy storage and internal combustion engine controlled flameout. It is driven by pure internal combustion engine at medium and high speeds. When braking, a hydraulic pump/motor is used to recover braking energy. The hydraulic pump/motor, clutch, transmission and hybrid electronic control unit are used to realize the high efficiency and low emission of the mechanical-hydraulic hybrid system.

A machine-hydraulic hybrid power transmission system of the present invention includes an internal combustion engine electronic control unit 1, an internal combustion engine 2, a starter motor 3, a transmission 10, a clutch 11, and an internal combustion engine starter key position sensor 17; it is characterized in that it also includes a two-position three-way valve A4, high-pressure accumulator 5, pressure sensor 6, hydraulic control check valve 7, two-position three-way valve B8, hybrid electric control unit 9, hydraulic pump/motor 12, low-pressure accumulator 13, pump/motor displacement Electro-hydraulic control device 14, brake pedal position sensor 15, accelerator pedal position sensor 16; a hydraulic pump/motor 12 is rigidly connected between the internal combustion engine 2 and the clutch 11, the high-pressure oil port of the hydraulic pump/motor 12 is connected to the two-position three The through valve A4 is connected, and is connected with the high-pressure accumulator 5 through the hydraulic control check valve 7; the low-pressure oil port of the hydraulic pump/motor 12 is connected with the low-pressure accumulator 13; the hydraulic pump/motor 12 is also connected through the two-position three-way valve B8 is connected with the hydraulic control check valve 7; the pressure sensor 6 of the high-pressure accumulator 5, the brake pedal position sensor 15, the accelerator pedal position sensor 16 and the internal combustion engine starter key position sensor 17 are connected to the hybrid power control unit 9 through cables; The power control unit 9 is connected to a hydraulic pump/motor 12 through a pump/motor displacement electro-hydraulic control device 14 .

Both the high-pressure accumulator 5 and the low-pressure accumulator 13 are common bladder accumulators, one side of the air bladder is filled with nitrogen, and the other side is filled with hydraulic oil. The pressure upper limit range of the high-pressure accumulator 5 is 25-40Mpa, the pressure lower limit range of the high-pressure accumulator 5 is 10-15Mpa, and the pressure range of the low-pressure accumulator 13 is 0.1-0.5Mpa. The pressure regulator sets the pressure limit.

When the two-position three-way valve B8 is in p1 and the two-position three-way valve A4 is in the connected state of p4, the high-pressure oil from the high-pressure accumulator 5 flows to the hydraulic control check valve 7 through the two-position three-way valve B8, so that the hydraulic control single Open to the valve 7 in the opposite direction, so that the high-pressure oil from the high-pressure accumulator 5 flows into the hydraulic pump/motor 12 through the two-position three-way valve A4, and drives the hydraulic pump/motor to rotate; when the two-position three-way valve B8 is in the disconnected state of p2 , the hydraulic control check valve 7 is reversely closed. When the two-position three-way valve A4 is in the unloading position of p3, the hydraulic pump/motor 12 is in the unloading state; when the two-position three-way valve A4 is in the on-state of p4 and the two-position three-way valve B8 is in the off-state of p2, the vehicle inertia passes through the transmission 10. The clutch 11 drives the hydraulic pump/motor 12 to rotate, and the pumped high-pressure oil enters the high-pressure accumulator 5 through the hydraulic control check valve 7 for storage. The hybrid electric control unit 9 receives the pressure signal g from the high-pressure accumulator pressure sensor 6, the brake pedal position signal a, the accelerator pedal position signal b, the internal combustion engine start key signal c, and the internal combustion engine state signal h from the internal combustion engine electronic control unit 1 . The hybrid electric control unit 9 sends the starter motor control signal j, the hydraulic pump/motor control signal d, the two-position three-way valve A4 control signal e, the two-position three-way valve B8 control signal f and the internal combustion engine control signal i to realize the electric motor of the internal combustion engine or Hydraulic pump/motor starting, internal combustion engine-hydraulic hybrid acceleration, hydraulic pump/motor recovery of braking energy, hydraulic pump/motor utilization of braking energy, internal combustion engine automatic flameout and start, etc.

The working mechanism of the device of the present invention is:

1) The clutch 11 is used to realize the power connection or disconnection of the hydraulic pump/motor 12 and the transmission 10 .

2) The hydraulic pump/motor 12 is rigidly connected to the power output shaft of the internal combustion engine 2 . When the internal combustion engine rotates, the hydraulic pump/motor rotates accordingly. By adjusting the swash plate angle of the hydraulic pump/motor, the hydraulic pump/motor can operate under load (the swash plate angle is greater than zero) or without load (the swash plate angle is equal to zero).

3) When the hydraulic pump/motor 12 is used to recover braking energy or the hydraulic pump/motor drives the vehicle, the internal combustion engine 2 rotates following the hydraulic pump/motor. In order to reduce the pump energy consumed by the internal combustion engine following the rotation, instructions are sent through the hybrid electric control unit 9 To the internal combustion engine electronic control unit 1, drive the variable valve timing mechanism and close the intake and exhaust valves at the same time, so that the piston becomes a gas spring. When the internal combustion engine is required to work, the hybrid electric control unit 9 sends an instruction to the internal combustion engine electronic control unit 1 to restore the timing of the intake and exhaust valves to the normal value.

4) The airbag accumulator is used to store hydraulic oil. A high-pressure accumulator 5 is used to store high-pressure oil pumped out by the hydraulic pump/motor 12 , and a low-pressure accumulator 13 is used to store low-pressure return oil from the hydraulic pump/motor 12 .

5) When the motor vehicle brakes or the internal combustion engine 2 is running under load, the hydraulic pump/motor 12 is in the hydraulic pump working condition, and the hydraulic pump/motor 12 converts the braking energy of the motor vehicle into high-pressure oil and stores it in the high-pressure accumulator 5, realizing Recovery of braking energy; when the motor vehicle starts, the hydraulic pump/motor 12 is in the hydraulic motor working condition, the high-pressure oil stored in the high-pressure accumulator 5 drives the hydraulic pump/motor 12 to rotate, and the power is realized through the clutch 11 and the transmission 10 output.

6) The hybrid electric control unit 9 controls the two-position three-way valve B8 to be in the connected state p1 by sending the control signal f of the two-position three-way valve B8 to realize the reverse opening of the hydraulic control check valve 7 and controls the two-position three-way valve B8 In the disconnected state p2, the liquid control check valve 7 is closed.

7) The hybrid electric control unit 9 controls the two-position three-way valve A4 to be in the on-state p4 by sending the two-position three-way valve A4 control signal e, so that the hydraulic pump/motor 12 pumps oil to high pressure through the hydraulic control check valve 7 The accumulator 5 or the hybrid electric control unit 9 realizes the reverse opening of the hydraulic control check valve 7, so that the high-pressure oil stored in the high-pressure accumulator 5 can be used to drive the hydraulic pump/motor 12 to rotate and output torque. The initial or default position of the 2/3-way valve A4 is p3, and the initial or default position of the 2/3-way valve B8 is p2.

This device adopts the following control strategy to realize the efficient operation of the machine-hydraulic hybrid power system. When the internal combustion engine 2 is started, the hydraulic pump/motor 12 is used to drag the internal combustion engine 2 to more than 800rpm to achieve efficient starting. If the oil pressure of the high pressure accumulator 5 is lower than the pressure upper limit range, the conventional electric motor 3 is used to start. When the vehicle is hydraulically started, the hydraulic pump/motor 12 is used to drive the vehicle until the vehicle speed reaches the third gear. After the transmission can be directly engaged in third gear, it is converted into the internal combustion engine 2 alone or the machine-hydraulic hybrid power to drive the vehicle; if the oil pressure of the high-pressure accumulator 5 is under pressure In the lower limit range, the internal combustion engine 2 is used to independently drive the vehicle to start. In the low-speed, low-load driving condition of the vehicle, the hybrid electric control unit 9 sends instructions to the internal combustion engine electronic control unit 1 to optimize the internal combustion engine 2 to a high-efficiency working area, and the excess internal combustion engine energy drives the hydraulic pump/motor 12 low-pressure accumulators The low-pressure oil in 13 is pumped to the high-pressure accumulator 5 for storage. When the oil pressure in the high-pressure accumulator 5 reaches the pressure upper limit range, the hybrid power electronic control unit 9 sends the internal combustion engine control signal i to the internal combustion engine electronic control unit 1 to shut down The internal combustion engine 2 and the hybrid electric control unit 9 issue control commands f, e, d to make the hydraulic pump/motor 12 in the motor working condition, the two-position three-way valve A4 is in the on state p4, and the two-position three-way valve B8 is in the on state p1, the hydraulic oil stored in the high-pressure accumulator 5 drives the hydraulic pump/motor 12 to drive the vehicle through the clutch 11 and the transmission 10; The motor 12 starts the internal combustion engine 2, and so on. When the vehicle is running at a medium or high speed, the internal combustion engine 2 alone or in combination with the hydraulic pump/motor 12 drives the vehicle to travel. When the brake pedal is depressed, during the free stroke stage of the brake pedal, the hybrid electric control unit 9 issues a control command to make the hydraulic pump/motor 12 in the pump working condition, and the two-position three-way valve A4 is in the on-state p4, The two-position three-way valve B8 is in the disconnected state p2, and the hydraulic energy recovery of braking energy is realized through the hydraulic pump/motor 12 .

The energy saving and emission reduction effects of the present invention are reflected in:

The rotational speed of the internal combustion engine and the speed of the vehicle with the mechanical-hydraulic hybrid system are no longer at a fixed speed ratio, so that the internal combustion engine can often work in a high-efficiency and low-emission area. In the low-speed and low-load condition of the vehicle, the use of controlled flameout of the internal combustion engine, recovery of braking energy by the hydraulic pump/motor and starting of the internal combustion engine by the hydraulic pump/motor can greatly improve the thermal efficiency of the internal combustion engine and reduce emissions. When the vehicle is parked, the internal combustion engine is turned off to save fuel or the internal combustion engine is in the lowest fuel consumption working area, the transmission is in the neutral position, and the excess internal combustion engine output power is used to drive the hydraulic pump/motor to pump the low-pressure oil in the low-pressure accumulator into the high-pressure accumulator Stored so that the hydraulic pump/motor can be used again to start the internal combustion engine or drive the vehicle off the ground. By controlling the flameout of the internal combustion engine and making the internal combustion engine often operate in the low fuel consumption area, the emission can be greatly reduced while saving fuel.

internal combustion engine start

Turn the vehicle key to the starting ignition position, the clutch 11 is combined, and the transmission 10 is in neutral. The hybrid electric control unit 9 receives the internal combustion engine start key signal c and the high-pressure accumulator pressure signal g, and if it is determined that the pressure in the high-pressure accumulator 5 is lower than the lower pressure range, it sends out a starter motor control signal j, which is driven by the starter motor 3 The flywheel rotates to realize the starting of the electric motor of the internal combustion engine; if it is determined that the pressure in the high-pressure accumulator 5 is at or higher than the lower pressure limit range, the hybrid electric control unit 9 sends a control command d to the pump/motor displacement electro-hydraulic control device 14 to make the hydraulic pressure The pump/motor 12 is in the motor working condition, and the control commands e and f are issued to make the two-position three-way valve A4 in the on state p4, the two-position three-way valve B8 in the on state p1, and the hydraulic pressure stored in the high-pressure accumulator 5 The oil drives the hydraulic pump/motor 12 to rotate at a high speed to realize the starting of the hydraulic pump/motor of the internal combustion engine. When starting the motor, the internal combustion engine can only be dragged to about 250rpm to start ignition. At this time, the fuel injection volume of the internal combustion engine is more than 2-5 times the normal amount, and the mixture gas is too thick, resulting in high fuel consumption and emissions; Drag the internal combustion engine above 800rpm and start to ignite. At this time, the fuel injection quantity of the internal combustion engine is about 1 times the normal amount, and the mixture gas is near the theoretical air-fuel ratio, which can greatly reduce the starting fuel consumption and efficiently convert the internal combustion engine emissions through the catalytic converter.

The hybrid electric control unit 9 receives the internal combustion engine start key signal c and the high-pressure accumulator pressure signal g. If it is determined that the pressure in the high-pressure accumulator 5 reaches the pressure upper limit range, the internal combustion engine 2 will not start, and the accelerator pedal position signal will be received. After b, the hydraulic pump/motor 12 is used to directly drive the vehicle to start.

vehicle start

Vehicle starting is divided into two working conditions: internal combustion engine starting and hydraulic pump/motor starting. The hybrid electronic control unit 9 determines that the vehicle is in the starting state according to the start key signal c and the accelerator pedal position signal b. If the internal combustion engine 2 is in working condition when the vehicle is started, the internal combustion engine power is used to start the vehicle;

internal combustion engine power start

When the vehicle starts, the hand brake is released, the clutch 11 is combined, and the transmission 10 is put into first gear. The power of the internal combustion engine 2 is transmitted to the differential, half shafts and wheels through the hydraulic pump/motor 12, the clutch 11 and the transmission 10, so as to realize the starting of the vehicle driven by the internal combustion engine. At this time, the hybrid electric control unit 9 sends a control command d to the pump/motor displacement electro-hydraulic control device 14 so that the swash plate angle of the hydraulic pump/motor 12 is zero degrees and is in an unloaded state.

Hydraulic pump/motor powered starting

When the vehicle starts, the hand brake is released, the clutch 11 is combined, and the transmission 10 is put into first gear. The hybrid electric control unit 9 judges that the oil pressure in the high-pressure accumulator 5 reaches the pressure upper limit range according to the signal g from the oil pressure sensor 6, and then sends a control command d to the pump/motor displacement electro-hydraulic control device 14 to make the hydraulic pump/motor The motor 12 is in the motor mode and determines the increase rate of the swash plate angle according to the change rate of the accelerator pedal position signal b. The power of the hydraulic pump/motor is transmitted to the differential, half shaft and wheels through the clutch 11 and the transmission 10, so as to realize the smooth hydraulic pressure of the vehicle. The pump/motor starts.

Vehicle running at low speed and low load

In the low-speed, low-load driving condition of the vehicle, the hybrid electric control unit 9 sends instructions to the internal combustion engine electronic control unit 1 to optimize the internal combustion engine 2 to a high-efficiency working area, and the excess internal combustion engine energy drives the hydraulic pump/motor 12 low-pressure accumulators The low-pressure oil in 13 is pumped into the high-pressure accumulator 5 for storage, and when the oil pressure of the high-pressure accumulator 5 reaches the pressure upper limit range, the internal combustion engine 2 is closed. The hybrid electric control unit 9 issues control commands f, e, d to make the hydraulic pump/motor 12 in the motor working condition, the two-position three-way valve A4 is in the on-state p4, the two-position three-way valve B8 is in the on-state p1, and stored The hydraulic oil in the high-pressure accumulator 5 drives the hydraulic pump/motor 12 to drive the vehicle through the clutch 11 and the transmission 10; Start the internal combustion engine 2, and so on.

vehicle speeding up

Vehicle acceleration is divided into two working conditions: internal combustion engine acceleration and internal combustion engine and hydraulic pump/motor hybrid acceleration. The hybrid electronic control unit 9 determines that the vehicle is in an accelerating state according to the accelerator pedal position signal b. When the vehicle accelerates, the oil pressure in the high-pressure accumulator 15 is in the range of the lower pressure limit, then the internal combustion engine power is used to accelerate the vehicle, and the power of the internal combustion engine 2 is transmitted to the differential through the hydraulic pump/motor 12, clutch 11 and transmission 10 in an unloaded state. transmission, half shafts and wheels to accelerate the internal combustion engine of the vehicle. If the oil pressure in the high-pressure accumulator 5 reaches the pressure upper limit range, the internal combustion engine and the hydraulic pump/motor hybrid power are used to accelerate. The hybrid electric control unit 9 sends a control command d to the pump/motor displacement electro-hydraulic control device 14 to make the hydraulic pump/motor 12 in motor mode and determines the increase rate of the swash plate angle according to the change rate of the accelerator pedal position signal b. At this time, the power of the internal combustion engine 2 and the hydraulic pump/motor 12 is transmitted to the differential, the axle shaft and the wheels through the clutch 11 and the transmission 10, so as to realize the hybrid acceleration of the internal combustion engine and the hydraulic pump/motor of the vehicle. As the vehicle accelerates, the transmission can gradually shift into a higher gear.

Vehicle driving at high speed

When the vehicle is running at a medium-high speed, the internal combustion engine 2 alone or in combination with the hydraulic pump/motor 12 drives the vehicle, and the control process is similar to 3.5.4.

Vehicle slows down

Vehicle deceleration is divided into three working conditions: coasting, slow deceleration (frequent slow braking in congested urban areas) and fast deceleration (sudden braking). The hybrid electric control unit 9 judges that the vehicle is in a deceleration state according to the brake pedal position signal a and the accelerator pedal position signal b, and judges that the vehicle is in a slow deceleration or fast deceleration state according to the acceleration of the brake pedal position signal. When the vehicle is in the coasting state, both the accelerator pedal and the brake pedal are released. At this time, the driving kinetic energy of the vehicle should be used to achieve the longest possible coasting distance, and the hydraulic system does not recover the coasting energy. When the vehicle is in the state of slow deceleration, release the accelerator pedal and slowly step on the brake pedal. During the free travel stage of the brake pedal, use the hydraulic system to recover the kinetic energy of the vehicle to realize the initial deceleration of the vehicle. If the required deceleration intensity is still not reached, Then, in the working stroke of the pedal, the vehicle is braked more quickly through the mechanical braking system of the vehicle. When the vehicle is in a state of rapid deceleration, it is necessary to quickly decelerate or even stop the vehicle. At this time, the brake pedal must be stepped on quickly, so that the brake pedal can quickly enter the working stroke to realize rapid braking of the vehicle. During the free stroke of the braking process, hydraulic pressure The pump/motor adopts a large swash plate angle to quickly recover the braking energy and together with the mechanical braking system, realize quick braking and stopping.

vehicle taxiing

During the coasting phase of the vehicle, both the brake pedal and the accelerator pedal are released. The hybrid electronic control unit 9 determines that the vehicle is in a coasting state according to the brake pedal position signal a and the accelerator pedal position signal b. The hybrid electric control unit 9 sends a control command d to the pump/motor displacement electro-hydraulic control device 14 so that the swash plate angle of the hydraulic pump/motor 12 is zero degrees, and the pump/motor is in the overflow unloading state, and sends a control command e to make the two-position The three-way valve A4 is in the p3 unloading position. During taxiing, the flameout of the internal combustion engine can be manually or electronically controlled to save fuel.

Vehicle slows down

During the slow deceleration stage of the vehicle, the accelerator pedal is released, and the brake pedal is slowly stepped on. The hybrid electric control unit 9 determines that the vehicle is in a slow deceleration state according to the rate of change of the brake pedal position signal a. During the free travel of the brake pedal, the hydraulic pump/motor is used to recover the driving kinetic energy of the vehicle. The hybrid electric control unit 9 sends a control command d to the pump/motor displacement electro-hydraulic control device 14 to make the hydraulic pump/motor 12 in pumping mode and determines the increase rate of the swash plate angle according to the change rate of the brake pedal position signal a. At this time, the kinetic energy of the vehicle drives the hydraulic pump/motor 12 to rotate through the transmission 10 and the clutch 11. After pressurizing the low-pressure oil stored in the low-pressure accumulator 13, it is pumped into the high-pressure accumulator 5 through the hydraulic control check valve 7. Realize hydraulic energy recovery of braking energy.

vehicle deceleration

During the rapid deceleration stage of the vehicle, the accelerator pedal is in a released state, and the brake pedal is quickly stepped on. The hybrid electronic control unit 9 determines that the vehicle is in a fast deceleration state according to the rate of change of the brake pedal position signal a. The hybrid electric control unit 9 sends a control command d to the pump/motor displacement electro-hydraulic control device 14 to make the hydraulic pump/motor 12 in pumping mode and determines the increase rate of the swash plate angle according to the change rate of the brake pedal position signal a. During the braking free travel during the fast deceleration phase of the vehicle, the hydraulic pump/motor adopts a large swash plate angle to quickly recover the braking energy and together with the mechanical braking system, realize rapid braking and parking.

vehicle parking

When the vehicle brakes to stop, the accelerator pedal is in the state of release, the brake pedal is in the state of release or depression, and the transmission is in neutral. The hybrid electric control unit 9 judges that the vehicle is in a stopped state according to the brake pedal position signal a, the accelerator pedal position signal b and the vehicle speed signal contained in the internal combustion engine state signal h sent from the internal combustion engine electronic control unit 1 to the hybrid electric control unit 9 . If the hybrid electric control unit 9 receives the pressure sensor signal g of the high-pressure accumulator 5 and determines that the oil pressure reaches the pressure upper limit range, it will send a flameout command to the internal combustion engine electronic control unit 1 to cause the internal combustion engine to be flamed out. Otherwise, the hybrid electric control unit 9 sends instructions to the internal combustion engine electronic control unit 1 to optimize the internal combustion engine 2 to the high-efficiency working area, and the energy of the internal combustion engine is stored in the high-pressure accumulator 5 through the hydraulic pump/motor. When the high-pressure accumulator 5 When the oil pressure reaches the pressure upper limit range, the internal combustion engine 2 is turned off.

Description of drawings

1, the internal combustion engine electric control unit among the figure 1 structure of the present invention; 2, internal combustion engine; 3, starter motor; 4, two-position three-way valve A; 5, high pressure accumulator; 6, pressure sensor; 7 Hydraulic control check valve; 8. Two-position three-way valve B; 9. Hybrid electric control unit; 10. Transmission; 11. Clutch; 12. Hydraulic pump/motor; 13. Low-pressure accumulator; 14. Pump/motor Displacement electro-hydraulic control device; 15. Brake pedal position sensor; 16. Accelerator pedal position sensor; 17. Internal combustion engine starting key position sensor; a. Brake pedal position signal; b. Accelerator pedal position signal; c. Internal combustion engine starting key Position signal; d, hydraulic pump/motor control signal; e, two-position three-way valve A4 control signal; f, two-position three-way valve B8 control signal; g, high pressure accumulator 5 pressure signal; h, from the internal combustion engine electric control Internal combustion engine status signal of unit 1; i, internal combustion engine control signal; j, starter motor control signal. p3 two-position three-way valve A4 unloading position; p4 two-position three-way valve A4 on position; p1 two-position three-way valve B8 on position; p2 two-position three-way valve B8 off position;

Detailed ways

Based on a kind of mechanical-hydraulic hybrid power transmission system and control method proposed by the present invention, a 1.6L sedan equipped with a manual transmission and reaching the national 4 emission standard has been refitted, and the displacement of the hydraulic pump/motor adopted is 56mL/rpm, Speed range 0-3000rpm, rated power 45KW. The refitted vehicle was tested for fuel consumption in accordance with the national standard GB/T19233-2003 "Test Method for Fuel Consumption of Light Vehicles", and for emission testing in accordance with the national standard GB18352.3-2005 "Limits and Measurement Methods of Pollutant Emissions for Light Vehicles". The test results show that the refitted car can save 30% fuel than the original car in urban working conditions, and is equivalent to the original car in suburban working conditions. Comprehensive urban and suburban working conditions, compared with the original car, the refitted car saves 17% of fuel, reduces _CO2 emissions by 16.6%, _NOx emissions by 14.3%, CO by 45.4%, and HC 53.2%.

The test results of the above-mentioned whole vehicle show that adopting the mechanical-hydraulic hybrid power transmission system provided by the present invention can realize relatively large energy-saving and emission reduction of motor vehicles, and this technology will provide an effective technical approach for motor vehicles to achieve higher energy-saving standards .

Claims (2)

1. A machine-hydraulic hybrid power transmission system comprising an internal combustion engine electronic control unit (1), an internal combustion engine (2), a starter motor (3), a transmission (10), a clutch (11), and an internal combustion engine starter key position sensor (17); It is characterized in that it also includes two-position three-way valve A (4), high-pressure accumulator (5), pressure sensor (6), hydraulic control check valve (7), two-position three-way valve B (8), mixing Power electronic control unit (9), hydraulic pump/motor (12), low-pressure accumulator (13), pump/motor displacement electro-hydraulic control device (14), brake pedal position sensor (15), accelerator pedal position sensor (16); a hydraulic pump/motor (12) is rigidly connected between the internal combustion engine (2) and the clutch (11), and the high-pressure oil port of the hydraulic pump/motor (12) is connected with the two-position three-way valve A (4) , and is connected with the high-pressure accumulator (5) through the hydraulic control check valve (7); the low-pressure oil port of the hydraulic pump/motor (12) is connected with the low-pressure accumulator (13); the hydraulic pump/motor (12) also The two-position three-way valve B (8) is connected to the hydraulic control check valve (7); the pressure sensor (6) of the high-pressure accumulator (5), the brake pedal position sensor (15), the accelerator pedal position sensor (16 ) and the internal combustion engine starter key position sensor (17) are connected to the hybrid power control unit (9) through cables; the hybrid power control unit (9) is connected to the hydraulic pump/motor (12) through the pump/motor displacement electro-hydraulic control device (14) . 2. The control method of a mechanical-hydraulic hybrid transmission system according to claim 1, characterized in that the hybrid control unit (9) sends a control signal (f) of the two-position three-way valve B (8) to make the two-position When the three-way valve B (8) is in the on position, and the two-position three-way valve A (4) control signal (e) is sent to make the two-position three-way valve A (4) in the on position, at this time the pressure from the high-pressure accumulator The high-pressure oil in (5) flows to the hydraulic control check valve (7) through the two-position three-way valve B (8), so that the hydraulic control check valve (7) is reversely opened, resulting in the high pressure from the high-pressure accumulator (5) The oil flows into the hydraulic pump/motor (12) through the two-position three-way valve A (4), drives the hydraulic pump/motor (12) to work according to the working conditions of the motor, and the power of the hydraulic pump/motor (12) is transmitted to the transmission through the clutch (11) (10) driving the vehicle; When the two-position three-way valve B (8) is in the disconnected position, the hydraulic control check valve (7) is reversely closed, and the high-pressure oil stored in the high-pressure accumulator (5) cannot flow into the hydraulic pump/motor (12); When the two-position three-way valve A (4) is in the unloading position, the hydraulic pump/motor (12) is in the unloading state; the hybrid power control unit (9) sends the two-position three-way valve B (8) control signal (f) to make the two When the one-position three-way valve B (8) is in the off position, and the two-position three-way valve A (4) control signal (e) is sent to make the two-position three-way valve A (4) in the on position, the inertial kinetic energy of the vehicle passes through the transmission ( 10), the clutch (11) drives the hydraulic pump/motor (12) to rotate, drives the hydraulic pump/motor (12) to work according to the pump working conditions, and the pumped high-pressure oil passes through the two-position three-way valve A (4) and the hydraulic control unit The valve (7) enters the high-pressure accumulator (5) for storage; the hybrid power control unit (9) receives the pressure signal (g) from the high-pressure accumulator pressure sensor (6), the accelerator pedal position signal (a), the brake Pedal position signal (b), internal combustion engine start key signal (c) and internal combustion engine status signal (h) from internal combustion engine electronic control unit (1), send motor start control signal (j), hydraulic pump/motor control signal (d), Two-position three-way valve A (4) control signal (e), two-position three-way valve B (8) control signal (f) and internal combustion engine control signal (i).

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