阅读说明：本技术 一种电-机械-液压混合储能单元 (Electricity-machinery-hydraulic pressure hybrid energy storage unit ) 是由 王峰 林梓畅 徐兵 于 2021-09-02 设计创作，主要内容包括：本发明公开了一种电-机械-液压混合储能单元。本发明的蓄电池通过电机控制器与电机电连接,电机的输出轴与液压泵马达的输出轴同轴连接,液压泵马达的输出轴还与飞轮的输出轴同轴连接,液压泵马达与液压蓄能器之间通过三通油管相连通,液压泵马达的第一进出油口与液压油箱连通,液压泵马达的第二进出油口与液压蓄能器的进出油口分别与三通油管的第一连接口和第二连接口相连通,三通油管的第三连接口作为混合储能单元的进出油口。本发明通过液压泵马达完成机械能与液压能的互相转化,通过液压蓄能器提供短时间的大功率液压能充放。与传统的液压蓄能器储能相比,可实现高功率密度和高能量密度的混合储能。(The invention discloses an electric-mechanical-hydraulic hybrid energy storage unit. The storage battery is electrically connected with the motor through the motor controller, an output shaft of the motor is coaxially connected with an output shaft of a hydraulic pump motor, the output shaft of the hydraulic pump motor is also coaxially connected with an output shaft of the flywheel, the hydraulic pump motor is communicated with the hydraulic energy accumulator through a three-way oil pipe, a first oil inlet and outlet of the hydraulic pump motor is communicated with a hydraulic oil tank, a second oil inlet and outlet of the hydraulic pump motor and an oil inlet and outlet of the hydraulic energy accumulator are respectively communicated with a first connecting port and a second connecting port of the three-way oil pipe, and a third connecting port of the three-way oil pipe is used as an oil inlet and outlet of the hybrid energy storage unit. The hydraulic pump motor finishes the mutual conversion of mechanical energy and hydraulic energy, and the hydraulic accumulator provides high-power hydraulic energy charging and discharging in a short time. Compared with the traditional hydraulic accumulator energy storage, the hybrid energy storage with high power density and high energy density can be realized.)

1. An electro-mechanical-hydraulic hybrid energy storage unit, characterized by: the device comprises a flywheel (1), a storage battery (2), a motor controller (3), a motor (4), a hydraulic pump motor (5), a hydraulic oil tank (6) and a hydraulic energy accumulator (7);

the storage battery (2) is electrically connected with the motor (4) through the motor controller (3), the output shaft of the motor (4) is coaxially connected with the output shaft of the hydraulic pump motor (5), the output shaft of the hydraulic pump motor (5) is also coaxially connected with the output shaft of the flywheel (1), the hydraulic pump motor (5) is communicated with the hydraulic energy accumulator (7) through a three-way oil pipe, a first oil inlet and outlet of the hydraulic pump motor (5) is communicated with the hydraulic oil tank (6), a second oil inlet and outlet of the hydraulic pump motor (5) is communicated with a first connecting port and a second connecting port of the three-way oil pipe respectively, and a third connecting port of the three-way oil pipe is used as an oil inlet and outlet of the hybrid energy storage unit.

2. An electro-mechanical-hydraulic hybrid energy storage unit according to claim 1, characterized in that: the hydraulic pump motor (5) is driven by the motor, the hydraulic pump motor (5) is used as an electro-hydrostatic pump, and the flow of the hybrid energy storage unit, the hydraulic energy accumulator (7) and the electro-hydrostatic pump meet the following relationship:

Q＝Q_a+Q_p

wherein Q is the flow of the oil inlet and the oil outlet of the hybrid energy storage unit, and Q_aIs the flow of the hydraulic accumulator (7), Q_pIs the flow rate of the electro-hydrostatic pump.

3. An electro-mechanical-hydraulic hybrid energy storage unit according to claim 1, characterized in that: the hydraulic pump motor (5) is used as an electrostatic liquid pump, and the power of the hybrid energy storage unit, the power of the hydraulic energy accumulator (7) and the power of the electrostatic liquid pump meet the following relation:

P＝P_a+P_p+P_f

wherein P is the power of the hybrid energy storage unit, P_aFor the power of the hydraulic accumulator (7), P_pFor the power of an electro-static liquid pump, P_fIs the power of the flywheel (1).

4. An electro-mechanical-hydraulic hybrid energy storage unit according to claim 1, characterized in that: the hydraulic pump motor is a single hydraulic pump motor or a combination of two or more hydraulic pump motors.

5. An electro-mechanical-hydraulic hybrid energy storage unit according to claim 1, characterized in that: the hydraulic circuit of the hydraulic pump motor (5) is a closed hydraulic circuit or an open hydraulic circuit.

6. An electro-mechanical-hydraulic hybrid energy storage unit according to claim 1, characterized in that: the storage battery (2) is a battery pack or a super capacitor.

7. An electro-mechanical-hydraulic hybrid energy storage unit according to claim 1, characterized in that: the flywheel (1) is directly connected to an output shaft of the hydraulic pump motor (5) or is connected to the output shaft of the hydraulic pump motor through a clutch or a transmission mechanism.

8. An electro-mechanical-hydraulic hybrid energy storage unit according to claim 1, characterized in that: the motor (4) is directly connected with an output shaft of the hydraulic pump motor (5) or is connected with the output shaft of the hydraulic pump motor through a clutch or a transmission mechanism.

9. An electro-mechanical-hydraulic hybrid energy storage unit according to claim 1, characterized in that: the hydraulic accumulator (7) is a combination of more than two hydraulic accumulators or a single hydraulic accumulator.

Technical Field

The invention relates to a hydraulic energy storage unit, in particular to an electric-mechanical-hydraulic hybrid energy storage unit.

Background

The hydraulic energy storage unit is widely applied to the fields of engineering machinery, vehicles, ocean energy utilization and the like, wherein the most common hydraulic energy storage unit is a hydraulic energy accumulator which has high power density but has the following defects: 1) the energy density is low, the energy storage capacity is small, and the long-time energy release can not be realized; 2) the output hydraulic pressure of the hydraulic accumulator is quickly reduced to be below the pressure required by the system along with the release of the stored energy, so that the working stability of the system is influenced; 3) the energy charging of the energy storage system depends on the main power source, and when the energy storage state is low, a part of power needs to be distributed to charge the energy storage device, so that the power output of a load end can be influenced. The electro-hydrostatic pump can be driven by the motor to work under a pumping working condition, or work under a motor working condition to reversely drag the motor to work as a generator to perform mutual conversion on hydraulic energy and electric energy. The electric energy storage method has higher energy density but lower power density, cannot provide high-power energy charging and discharging, and the hydraulic energy accumulator and the flywheel have higher power density and can provide instantaneous high-power charging and discharging but lower energy density.

Disclosure of Invention

In view of the above problems in the art, the present invention provides an electro-mechanical-hydraulic hybrid energy storage unit, which combines energy storage of a flywheel with high power density, energy storage of a hydraulic accumulator, and an electric drive system with high energy density to realize a hybrid energy storage unit with high energy density and high power density.

The technical scheme adopted by the invention is as follows:

the invention comprises a flywheel, a storage battery, a motor controller, a motor, a hydraulic pump motor, a hydraulic oil tank and a hydraulic accumulator;

the battery passes through the machine controller and is connected with the motor electricity, the output shaft of motor and hydraulic pump motor's output shaft coaxial coupling, hydraulic pump motor's output shaft still with the output shaft coaxial coupling of flywheel, be linked together through tee bend oil pipe between hydraulic pump motor and the hydraulic energy storage ware, hydraulic pump motor is provided with two business turn over hydraulic fluid ports, hydraulic pump motor's first business turn over hydraulic fluid port passes through oil pipe and hydraulic tank intercommunication, hydraulic pump motor's second business turn over hydraulic fluid port and hydraulic energy storage ware business turn over hydraulic fluid port respectively with tee bend oil pipe's first connector and second connector be linked together, tee bend oil pipe's third connector is as mixing energy storage unit's first business turn over hydraulic fluid port, hydraulic pump motor's first business turn over hydraulic fluid port is as or not as mixing energy storage unit's second business turn over hydraulic fluid port.

The hydraulic pump motor is driven by the motor and serves as an electro-hydrostatic pump, and the flow of the hybrid energy storage unit and the flow of the hydraulic energy accumulator and the electro-hydrostatic pump meet the following relationship:

Q＝Q_a+Q_p

wherein Q is the flow of the oil inlet and the oil outlet of the hybrid energy storage unit, and Q_aFlow rate for hydraulic accumulators, Q_pIs the flow rate of the electro-hydrostatic pump.

The hydraulic pump motor is used as an electrostatic liquid pump, and the power of the hybrid energy storage unit and the power of the hydraulic energy accumulator and the electrostatic liquid pump meet the following relationship:

P＝P_a+P_p+P_f

wherein P is the power of the hybrid energy storage unit, P_aFor power of hydraulic accumulators, P_pFor the power of an electro-static liquid pump, P_fIs the power of the flywheel.

The hydraulic pump motor is a single hydraulic pump motor or a combination of two or more hydraulic pump motors.

The hydraulic circuit of the hydraulic pump motor is a closed hydraulic circuit or an open hydraulic circuit.

The storage battery is a battery pack or a super capacitor.

The flywheel is directly connected to the output shaft of the hydraulic pump motor or connected to the output shaft of the hydraulic pump motor through a clutch or a transmission mechanism.

The motor is directly connected with the output shaft of the hydraulic pump motor or connected with the output shaft of the hydraulic pump motor through a clutch or a transmission mechanism.

The hydraulic accumulator is a combination of more than two hydraulic accumulators or a single hydraulic accumulator.

The flywheel is connected to the shaft of the electro-hydrostatic pump, when small-power charging and discharging are carried out, electric energy and hydraulic energy are mainly converted by the motor, and the speed of the flywheel only has small fluctuation; when high-power charging and discharging are carried out, mechanical energy and hydraulic energy are mainly converted by the flywheel, and the speed of the flywheel has large fluctuation.

The flywheel provides high-power energy charging and discharging in a short time, and the electro-hydrostatic pump provides long-time low-power energy charging and discharging so as to meet the requirements of the energy storage system under different working conditions. When a large amount of energy needs to be absorbed in a short time, the flywheel can directly absorb high-power energy and release the energy when needed, or the flywheel can be used as a buffer to temporarily store the high-power energy, and then the motor generates electricity with low power and converts the electricity into electric energy to be stored; when the speed of the flywheel is low, the motor can accelerate the flywheel with low power for a long time, and the flywheel can be released once when the system needs high-power discharging.

The hydraulic accumulator provides high-power energy charging and discharging in a short time, and the electro-hydrostatic pump provides long-time low-power energy charging and discharging so as to meet the requirements on the energy storage system under different working conditions. When the energy storage state of the hydraulic energy accumulator is low, the electro-hydrostatic pump can charge the hydraulic energy accumulator and release the energy at one time when the system needs high-power energy release. In addition, in the energy discharging process of the energy accumulator, the electro-hydrostatic pump can work in an auxiliary mode, the upper limit of the charging and discharging power of the energy storage unit is improved, and meanwhile the pressure reduction speed of the energy accumulator is slowed down.

The invention has the beneficial effects that:

the electric energy storage has high energy density, and the flywheel energy storage and the hydraulic energy storage have high power density but lower energy density. The flywheel is connected to the output shaft of the motor and drives the hydraulic pump motor to rotate, and the outlet of the hydraulic pump motor is connected with the hydraulic accumulator in parallel. The motor provides low-power long-time mechanical energy for charging and discharging, the flywheel provides short-time high-power mechanical energy for charging and discharging, the hydraulic pump motor completes mutual conversion of mechanical energy and hydraulic energy, and the hydraulic accumulator provides short-time high-power hydraulic energy for charging and discharging. The integrated design can reduce the volume of the energy storage unit and is conveniently integrated into the design of a hydraulic system. Compared with the traditional hydraulic accumulator energy storage, the hybrid energy storage with high power density and high energy density can be realized.

Drawings

Fig. 1 is a schematic diagram of an electro-mechanical-hydraulic hybrid energy storage unit.

Fig. 2 is a schematic diagram of a series hydraulic hybrid system of the present invention for wheel drive of a wheel loader.

Fig. 3 is a schematic diagram of a front parallel hybrid system of the gearbox for wheel type driving of the wheel loader.

Fig. 4 is a schematic diagram of the rear parallel hybrid system of the gearbox for wheel type driving of the wheel loader according to the invention.

FIG. 5 is a schematic diagram of a front parallel hybrid transmission system of the present invention when used in a truck powertrain.

FIG. 6 is a schematic diagram of a transmission rear parallel hybrid system of the present invention when used in a truck powertrain.

In the figure: 1. the system comprises a flywheel, 2, a storage battery, 3, a motor controller, 4, a motor, 5, a hydraulic pump motor, 6, a hydraulic oil tank, 7, a hydraulic accumulator, 8, a hydraulic motor, 9, a vehicle main speed reducer, 10, an engine, 11, a hydraulic torque converter, 12, a gearbox, 13, a meshing gear pair, 14, a first clutch, 15, a second clutch, 16 and an engine hydraulic pump.

Detailed Description

The invention is described in further detail below with reference to the figures and the embodiments.

As shown in fig. 1, the present invention includes a flywheel 1, a storage battery 2, a motor controller 3, a motor 4, a hydraulic pump motor 5, a hydraulic oil tank 6, and a hydraulic accumulator 7;

the storage battery 2 is electrically connected with the motor 4 through the motor controller 3, the output shaft of the motor 4 is coaxially connected with the output shaft of the hydraulic pump motor 5, the output shaft of the hydraulic pump motor 5 is also coaxially connected with the output shaft of the flywheel 1, the hydraulic pump motor 5 is communicated with the hydraulic accumulator 7 through a three-way oil pipe, the hydraulic pump motor 5 is provided with two oil inlet and outlet ports, a first oil inlet and outlet port of the hydraulic pump motor 5 is communicated with the hydraulic oil tank 6 through an oil pipe, a second oil inlet and outlet port of the hydraulic pump motor 5 and an oil inlet and outlet port of the hydraulic accumulator 7 are respectively communicated with a first connecting port and a second connecting port of the three-way oil pipe, a third connecting port of the three-way oil pipe is used as a first oil inlet and outlet port of the hybrid energy storage unit, in specific implementation, the first oil inlet and outlet port of the hydraulic pump motor 5 is used as or not used as a second oil inlet and outlet port of the hybrid energy storage unit.

The hydraulic pump motor 5 is used as an electro-hydrostatic pump, and the flow of the hybrid energy storage unit, the hydraulic accumulator 7 and the electro-hydrostatic pump satisfy the following relationship:

Q＝Q_a+Q_p

wherein Q is the flow of the oil inlet and the oil outlet of the hybrid energy storage unit, and Q_aFor the flow of the hydraulic accumulator 7, Q_pIs the flow rate of the electro-hydrostatic pump.

The hydraulic pump motor 5 is used as an electrostatic liquid pump, and the power of the hybrid energy storage unit and the power of the hydraulic energy accumulator 7 and the electrostatic liquid pump satisfy the following relations:

P＝P_a+P_p+P_f

wherein P is the power of the hybrid energy storage unit, P_aFor the power of the hydraulic accumulator 7, P_pFor the power of an electro-static liquid pump, P_fIs the power of the flywheel 1.

The hydraulic pump motor is a single hydraulic pump motor or a combination of two or more hydraulic pump motors.

The hydraulic circuit of the hydraulic pump motor 5 is either a closed hydraulic circuit or an open hydraulic circuit.

The hydraulic pump motor 5 is a variable displacement hydraulic pump motor.

The storage battery 2 is a battery pack or a super capacitor.

The flywheel 1 is connected to the output shaft of the hydraulic pump motor 5 directly or through a clutch or a transmission mechanism.

The motor 4 is directly connected with the output shaft of the hydraulic pump motor 5 or connected with the output shaft of the hydraulic pump motor 5 through a clutch or a transmission mechanism.

The hydraulic accumulator 7 is a combination of two or more hydraulic accumulators or a single hydraulic accumulator.

The flywheel is connected to the shaft of the electro-hydrostatic pump, when small-power charging and discharging are carried out, electric energy and hydraulic energy are mainly converted by the motor, and the speed of the flywheel only has small fluctuation; when high-power charging and discharging are carried out, mechanical energy and hydraulic energy are mainly converted by the flywheel, and the speed of the flywheel has large fluctuation.

The flywheel is connected to a shaft of the electro-static liquid pump, low-power long-time hydraulic energy charging and discharging is provided through the electro-static liquid pump, and short-time high-power hydraulic energy charging and discharging is provided through the flywheel. When a large amount of energy needs to be absorbed in a short time, the flywheel can directly absorb high-power energy and release the energy when needed, or the flywheel can be used as a buffer to temporarily store the high-power energy, and then the motor generates electricity with low power and converts the electricity into electric energy to be stored; when the speed of the flywheel is low, the motor can accelerate the flywheel with low power for a long time, and the flywheel can be released once when the system needs high-power discharging.

The hydraulic accumulator provides high-power energy charging and discharging in a short time, and the electro-hydrostatic pump provides long-time low-power energy charging and discharging so as to meet the requirements on the energy storage system under different working conditions. When the energy storage state of the hydraulic energy accumulator is low, the electro-hydrostatic pump can charge the hydraulic energy accumulator and release the energy at one time when the system needs high-power energy release. In addition, in the energy discharging process of the energy accumulator, the electro-hydrostatic pump can work in an auxiliary mode, the upper limit of the charging and discharging power of the energy storage unit is improved, and meanwhile the pressure reduction speed of the energy accumulator is slowed down.

The embodiment of the invention used for different power systems and the implementation working process thereof are as follows:

example 1

Fig. 2 is a schematic diagram of a series hydraulic hybrid system for a wheel loader travel drive of the present invention. The wheel loader is widely applied engineering machinery, a common hydrostatic transmission system for walking and driving of small and medium-sized wheel loaders is applied to the hydrostatic transmission system of the wheel loader.

The hydrostatic transmission system comprises an engine hydraulic pump 16, a hydraulic motor 8, a vehicle main speed reducer 9 and an engine 10, an output shaft of the engine 10 is coaxially connected with an output shaft of the engine hydraulic pump 16, two oil inlet and outlet ports of the engine hydraulic pump 16 are respectively communicated with two oil inlet and outlet ports of the hydraulic motor 8, the engine hydraulic pump 16 and the hydraulic motor 8 form a hydrostatic transmission loop, the output shaft of the hydraulic motor 8 is connected with the vehicle main speed reducer 9 through a transmission shaft, and an oil pipe connected between the engine hydraulic pump 16 and the hydraulic motor 8 is communicated with a first oil inlet and outlet port of the electro-hydraulic hybrid energy storage unit. The hydraulic circuit of the hydraulic pump motor 5 of the electro-hydraulic hybrid energy storage unit in this embodiment is an open hydraulic circuit.

The main power source is an engine 10, a main hydraulic pump 16 is driven, a hydraulic motor 8 is driven through a hydrostatic transmission circuit, the hydraulic motor 8 drives a vehicle main speed reducer 9, and finally the vehicle main speed reducer 9 drives vehicle wheels to run. The parallel hybrid energy storage unit can ensure that the hydraulic pressure of the hydrostatic transmission loop is in a relatively stable level on one hand by controlling the hydraulic pressure of the oil inlet and the oil outlet and the flow of the oil inlet and the oil outlet, and reduce system vibration caused by sudden pressure change; on the other hand, the power matching of the engine and the load can be adjusted through energy charging and discharging, the problem that the power matching of the engine and the load is poor when the load speed changes too fast so that the working condition of the engine is worsened is solved, and the main power source can work stably. Meanwhile, the hybrid energy storage unit can recover braking energy and provide auxiliary power, and the engine works in a higher efficiency range in a mode of energy storage and reutilization.

Example 2

Fig. 3 is a schematic diagram of a front parallel hybrid system of a gearbox for a wheel loader travel drive according to the present invention. For medium and large wheel loaders, the common drive train is hydrodynamic drive + gear shifting.

The power transmission system comprises a hydraulic motor 8, a vehicle main speed reducer 9, an engine 10, a hydraulic torque converter 11, a gearbox 12 and a meshing gear pair 13;

two oil inlets and outlets of the hydraulic motor 8 are respectively communicated with a first oil inlet and outlet of the electro-hydraulic hybrid energy storage unit and the hydraulic oil tank 6, and hydraulic loops of the hydraulic pump motor 5 and the hydraulic motor 8 are open hydraulic loops. The hydraulic pump motor 5 and the hydraulic motor 8 constitute a hydrostatic transmission circuit.

Two gears of the meshing gear pair 13 are meshed to form a gear pair, an output shaft of the hydraulic motor 8 is coaxially connected with one gear of the meshing gear pair 13, the other gear of the meshing gear pair 13 is respectively coaxially connected with an output shaft of the hydraulic torque converter 11 and an input shaft of the gearbox 12, the hydraulic torque converter 11 and the gearbox 12 are respectively arranged on two sides of the meshing gear pair 13, the input shaft of the hydraulic torque converter 11 is coaxially connected with an output shaft of the engine 10, the output shaft of the gearbox 12 is coaxially connected with the vehicle main speed reducer 9, and the output shaft of the hydraulic torque converter 11 and the input shaft of the gearbox 12 which are coaxially connected with the meshing gear pair 13 are both used as transmission shafts of the power transmission system.

The hydraulic energy of the electric-mechanical-hydraulic hybrid energy storage unit can be converted into mechanical energy through the hydraulic motor 8 and be collected into the main power transmission shaft, and the redundant mechanical energy output by the engine 10 can be converted into hydraulic energy and stored in the energy storage unit. On one hand, the working point of the engine can be adjusted to a high-efficiency working area through the storage and release of energy, the fuel economy is improved, and the exhaust emission is reduced; on the other hand, the hydraulic motors 8 connected in parallel can be used as auxiliary power, and can play a role in starting, stopping, accelerating, decelerating and other working conditions by utilizing the characteristics of quick response and high power density of the hydraulic power, so that the power performance and the manipulation performance of the wheel loader are improved.

Example 3

Fig. 4 is a schematic diagram of the rear parallel hybrid system of the gearbox for the wheel loader travel drive of the present invention. The main difference from embodiment 2 is that the position of the hydraulic motor 8 connected in parallel to the main drive shaft is different, and the operating conditions are also different. Compared with the parallel hybrid before the gearbox, the rotating speed of the parallel after the gearbox is lower and the torque requirement is higher, the rotating speed of the hydraulic motor 8 is lower.

The power transmission system comprises a hydraulic motor 8, a vehicle main speed reducer 9, an engine 10, a hydraulic torque converter 11, a gearbox 12 and a meshing gear pair 13;

two oil inlets and outlets of the hydraulic motor 8 are respectively communicated with a first oil inlet and outlet of the electro-hydraulic hybrid energy storage unit and the hydraulic oil tank 6, and hydraulic loops of the hydraulic pump motor 5 and the hydraulic motor 8 are open hydraulic loops. The hydraulic pump motor 5 and the hydraulic motor 8 constitute a hydrostatic transmission circuit.

Two gears of the meshing gear pair 13 are meshed to form a gear pair, an output shaft of the hydraulic motor 8 is coaxially connected with one gear of the meshing gear pair 13, the other gear of the meshing gear pair 13 is respectively coaxially connected with an output shaft of the gearbox 12 and a connecting shaft of the vehicle main reducer 9, the vehicle main reducer 9 and the gearbox 12 are respectively arranged on two sides of the meshing gear pair 13, the engine 10 is coaxially connected with an input shaft of the gearbox 12 through a hydraulic torque converter 11, and the output shaft of the gearbox 12 and the connecting shaft of the vehicle main reducer 9 which are coaxially connected with the meshing gear pair 13 are both used as transmission shafts of a power transmission system.

The hydraulic energy of the electric-mechanical-hydraulic hybrid energy storage unit can be converted into mechanical energy through the hydraulic motor 8 and be collected into the main power transmission shaft, and the redundant mechanical energy output by the engine 10 can be converted into hydraulic energy and stored in the hybrid energy storage unit. Likewise, on the one hand, by storing and releasing energy, the engine operating point can be adjusted to a high-efficiency operating region, fuel economy is improved, and exhaust emission is reduced; on the other hand, the hydraulic motors 8 connected in parallel can be used as auxiliary power, and can play a role in starting, stopping, accelerating, decelerating and other working conditions by utilizing the characteristics of quick response and high power density of the hydraulic power, so that the power performance and the manipulation performance of the wheel loader are improved.

Example 4

FIG. 5 is a schematic diagram of a front parallel hybrid transmission system of the present invention when used in a truck powertrain. Heavy-duty trucks also have a high demand on power performance, and particularly under the working conditions of starting, braking, ascending and the like, a power system needs to adapt to the low-speed working condition and the high-speed working condition of long-distance transportation at the same time, and the demands on an engine and a gearbox are high. Meanwhile, a large amount of braking energy is wasted when the truck is in a long-distance downhill, and an auxiliary heat dissipation device of a brake pad needs to be assembled.

The truck power system comprises a hydraulic motor 8, a vehicle final drive 9, an engine 10, a gearbox 12, a meshing gear pair 13, a first clutch 14 and a second clutch 15;

two oil inlets and outlets of the hydraulic motor 8 are respectively communicated with a first oil inlet and outlet of the electro-hydraulic hybrid energy storage unit and the hydraulic oil tank 6, and hydraulic loops of the hydraulic pump motor 5 and the hydraulic motor 8 are open hydraulic loops. The hydraulic pump motor 5 and the hydraulic motor 8 constitute a hydrostatic transmission circuit.

Two gears of the meshing gear pair 13 are meshed to form a gear pair, an output shaft of the hydraulic motor 8 is coaxially connected with one gear of the meshing gear pair 13 through a second clutch 15, the other gear of the meshing gear pair 13 is respectively coaxially connected with an input shaft of the gearbox 12 and an output shaft of the first clutch 14, the first clutch 14 and the gearbox 12 are respectively arranged on two sides of the meshing gear pair 13, the engine 10 is coaxially connected with the input shaft of the first clutch 14, and the output shaft of the gearbox 12 is coaxially connected with the main speed reducer 9 of the vehicle; the input shaft of the transmission case 12 and the output shaft of the first clutch 14, which are coaxially connected to the meshing gear pair 13, both serve as transmission shafts of the power transmission system.

On one hand, under the low-speed working conditions of starting and stopping, accelerating and decelerating, ascending and the like, the second clutch 15 is connected, the parallel hydraulic motor 8 provides auxiliary power, the power performance and the operation performance of the truck are improved by utilizing the quick response and high power density characteristics of the hydraulic power, and under the high-speed working condition, the second clutch 15 is disconnected, so that the work of an engine is not influenced; on the other hand, under the working conditions of braking, long-distance downhill and the like, the second clutch 15 is switched on, braking energy is recovered while braking force is provided, mechanical energy on the transmission shaft is converted and stored into the electric-mechanical-hydraulic hybrid energy storage unit through the hydraulic motor 8, and the mechanical energy is released under the working conditions of auxiliary starting and the like, so that the energy efficiency is improved, and meanwhile, the heat generated by braking is reduced.

Example 5

FIG. 6 is a schematic diagram of a transmission rear parallel hybrid system of the present invention when used in a truck powertrain. The main difference from embodiment 4 is that the position of the hydraulic motor 8 connected in parallel to the main drive shaft is different, and the operating conditions are also different. Compared with the parallel hybrid operation before the gearbox, the rotating speed of the hydraulic motor 8 is lower and the torque requirement is higher.

The truck power system comprises a hydraulic motor 8, a vehicle final drive 9, an engine 10, a gearbox 12, a meshing gear pair 13, a first clutch 14 and a second clutch 15;

two oil inlets and outlets of the hydraulic motor 8 are respectively communicated with a first oil inlet and outlet of the electro-hydraulic hybrid energy storage unit and the hydraulic oil tank 6, and hydraulic loops of the hydraulic pump motor 5 and the hydraulic motor 8 are open hydraulic loops. The hydraulic pump motor 5 and the hydraulic motor 8 constitute a hydrostatic transmission circuit.

Two gears of the meshing gear pair 13 are meshed to form a gear pair, an output shaft of the hydraulic motor 8 is coaxially connected with one gear of the meshing gear pair 13 through a second clutch 15, the other gear of the meshing gear pair 13 is respectively and coaxially connected with an output shaft of the gearbox 12 and a connecting shaft of the vehicle main reducer 9, the vehicle main reducer 9 and the gearbox 12 are respectively arranged on two sides of the meshing gear pair 13, the engine 10 is coaxially connected with an input shaft of the gearbox 12 through a first clutch 14, and the output shaft of the gearbox 12 and the connecting shaft of the vehicle main reducer 9 which are coaxially connected with the meshing gear pair 13 are both used as transmission shafts of the power transmission system.

Similarly, on one hand, when the truck is in low-speed working conditions such as start-stop, acceleration and deceleration, uphill and the like, the second clutch 15 is connected, the parallel hydraulic motor 8 provides auxiliary power, the power performance and the handling performance of the truck are improved by utilizing the characteristics of quick response and high power density of the hydraulic power, and the second clutch 15 is disconnected under the high-speed working condition without influencing the work of an engine; on the other hand, under the working conditions of braking, long-distance downhill and the like, the second clutch 15 is switched on, braking energy is recovered while braking force is provided, mechanical energy on the transmission shaft is converted and stored into the electric-mechanical-hydraulic hybrid energy storage unit through the hydraulic motor 8, and the mechanical energy is released under the working conditions of auxiliary starting and the like, so that the energy efficiency is improved, and meanwhile, the heat generated by braking is reduced.