阅读说明：本技术 一种串联式电液混合储能单元 (Series-type electro-hydraulic hybrid energy storage unit ) 是由 王峰 林梓畅 徐兵 于 2021-09-01 设计创作，主要内容包括：本发明公开了一种串联式电液混合储能单元。本发明包括液压蓄能器、蓄电池、电机控制器、电机和液压泵马达；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步机械连接,液压泵马达的第一进出油口与液压蓄能器的进出油口连通,液压泵马达的第二进出油口作为电液混合储能单元的进出油口,液压泵马达作为电静液泵。本发明一方面,液压蓄能器的油液经液压泵马达调节压力流量后输出,实现了主动的液压能量充放,能更好适应各种工况；另一方面,电静液泵的升压功能使得储能单元在蓄能器压力较低时也可以继续输出能量,增大了蓄能器的可用容积,从而增加了储能单元的能量密度。(The invention discloses a series-type electro-hydraulic hybrid energy storage unit. The invention comprises a hydraulic accumulator, a storage battery, a motor controller, a motor and a hydraulic pump motor; the storage battery is electrically connected with the motor through the motor controller, the output shaft of the motor is mechanically connected with the output shaft of the hydraulic pump motor synchronously, the first oil inlet and outlet of the hydraulic pump motor is communicated with the oil inlet and outlet of the hydraulic accumulator, the second oil inlet and outlet of the hydraulic pump motor serves as the oil inlet and outlet of the electro-hydraulic hybrid energy storage unit, and the hydraulic pump motor serves as an electro-static liquid pump. On one hand, the oil of the hydraulic accumulator is output after the pressure flow is regulated by the hydraulic pump motor, so that the active hydraulic energy charging and discharging is realized, and the hydraulic accumulator can better adapt to various working conditions; on the other hand, the boosting function of the electrostatic liquid pump enables the energy storage unit to continuously output energy when the pressure of the energy accumulator is low, so that the available volume of the energy accumulator is increased, and the energy density of the energy storage unit is increased.)

1. The series-type electro-hydraulic hybrid energy storage unit is characterized in that: the hydraulic pump comprises a hydraulic accumulator (1), a storage battery (2), a motor controller (3), a motor (4) and a hydraulic pump motor (5); the storage battery (2) is electrically connected with the motor (4) through the motor controller (3), an output shaft of the motor (4) is mechanically connected with an output shaft of the hydraulic pump motor (5) synchronously, a first oil inlet and outlet of the hydraulic pump motor (5) is communicated with an oil inlet and outlet of the hydraulic accumulator (1), and a second oil inlet and outlet of the hydraulic pump motor (5) serves as an oil inlet and outlet of the electro-hydraulic hybrid energy storage unit.

2. The series electro-hydraulic hybrid energy storage unit of claim 1, wherein: when the electro-hydraulic hybrid energy storage unit outputs energy, oil output by the hydraulic energy accumulator (1) is boosted or reduced in pressure by a hydraulic pump motor (5) driven by the motor (4) and then is output from an oil inlet and an oil outlet of the electro-hydraulic hybrid energy storage unit;

when the electro-hydraulic hybrid energy storage unit stores energy, oil input from an oil inlet and an oil outlet of the electro-hydraulic hybrid energy storage unit is input into the hydraulic energy accumulator (1) after being subjected to pressure reduction or pressure increase through the hydraulic pump motor (5).

3. The series electro-hydraulic hybrid energy storage unit of claim 1, wherein: the input and output flow of the electro-hydraulic hybrid energy storage unit, the input and output flow of the hydraulic pump motor (5) and the input and output energy of the hydraulic accumulator (1) satisfy the following relations:

Q＝Q_a＝Q_p

wherein Q is the oil inlet and outlet flow of the electro-hydraulic hybrid energy storage unit, and Q_aIs the flow rate of the hydraulic accumulator (1), Q_pThe flow rate of the hydraulic pump motor (5).

4. The series electro-hydraulic hybrid energy storage unit of claim 1, wherein: the hydraulic pump motor (5) is a fixed displacement hydraulic pump motor or an electronic proportional control variable displacement hydraulic pump motor; the hydraulic pump motor (5) is a single hydraulic pump motor or a combination of two or more hydraulic pump motors.

5. The series electro-hydraulic hybrid energy storage unit of claim 1, wherein: the hydraulic accumulator (1) is a combination of more than two hydraulic accumulators or a single hydraulic accumulator.

6. The series electro-hydraulic hybrid energy storage unit of claim 1, wherein: the storage battery (2) is a battery pack or a super capacitor.

7. The series electro-hydraulic hybrid energy storage unit of claim 1, wherein: the hydraulic pump motor (5) is used as an electro-static liquid pump, and the power of the electro-hydraulic hybrid energy storage unit and the power of the hydraulic accumulator and the electro-static liquid pump have the following relations:

P＝P_a+P_p

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

Technical Field

The invention relates to a hydraulic energy storage unit, in particular to a series-type electro-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 energy release time is limited; 2) the output hydraulic pressure of the hydraulic accumulator is related to the energy storage state, and the energy storage and release behavior of the hydraulic accumulator depends on the external pressure and the pressure of the accumulator and cannot be actively regulated; 3) in order to ensure the normal work of the system, the pressure change range of the hydraulic accumulator needs to be limited within a certain range, and the maximum capacity of the hydraulic accumulator cannot be fully utilized during design.

Disclosure of Invention

Aiming at the problems in the technology, the invention provides a series-type electro-hydraulic hybrid energy storage unit which can realize the storage and release of actively controlled hydraulic energy, can control the output flow and pressure of the hybrid energy storage unit through the control of the rotating speed and the steering of a motor, is integrated into an energy storage unit for use, and realizes the electro-hydraulic hybrid energy storage unit capable of controlling the active pressure flow.

The technical scheme adopted by the invention is as follows:

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

the storage battery is electrically connected with the motor through the motor controller, the output shaft of the motor is mechanically connected with the output shaft of the hydraulic pump motor synchronously, the hydraulic pump motor is provided with two oil inlet and outlet ports, a first oil inlet and outlet port of the hydraulic pump motor is communicated with an oil inlet and outlet port of the hydraulic accumulator, and a second oil inlet and outlet port of the hydraulic pump motor is used as an oil inlet and outlet port of the electro-hydraulic hybrid energy storage unit. The oil inlet and outlet of the electro-hydraulic hybrid energy storage unit is communicated with the hydrostatic transmission loop or directly connected with the oil inlet and outlet of hydraulic actuators such as a hydraulic cylinder and a hydraulic motor.

When the electro-hydraulic hybrid energy storage unit outputs energy, oil output by the hydraulic energy accumulator is boosted or reduced in pressure by a hydraulic pump motor driven by a motor and then is output from an oil inlet and an oil outlet of the electro-hydraulic hybrid energy storage unit;

when the electro-hydraulic hybrid energy storage unit stores energy, oil input from an oil inlet and an oil outlet of the electro-hydraulic hybrid energy storage unit is input into the hydraulic energy accumulator after being subjected to pressure reduction or pressure increase through the hydraulic pump motor.

The input and output flow of the electro-hydraulic hybrid energy storage unit, the input and output flow of the hydraulic pump motor and the input and output energy of the hydraulic accumulator satisfy the following relations:

Q＝Q_a＝Q_p

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

The hydraulic pump motor is a fixed displacement hydraulic pump motor or a variable displacement hydraulic pump motor controlled by an electronic proportion; the hydraulic pump motor is a single hydraulic pump motor, or a combination of two or more hydraulic pump motors.

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

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

The hydraulic pump motor is used as an electro-static liquid pump, and the power of the electro-hydraulic hybrid energy storage unit and the power of the hydraulic energy accumulator and the electro-static liquid pump have the following relations:

P＝P_a+P_p

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

On one hand, the oil of the energy accumulator is output after the pressure flow is regulated by the hydraulic pump motor, so that the active hydraulic energy charging and discharging is realized, and the energy accumulator can better adapt to various working conditions; on the other hand, the pressure regulating function of the electrostatic liquid pump enables the energy storage unit to output or store energy at high pressure when the pressure of the energy accumulator is low, the available pressure range of the energy accumulator is enlarged, the available capacity of the energy accumulator is improved, and the energy density of the energy storage unit is increased.

When the energy storage state of the hydraulic energy accumulator is low, the pressure is low, the electro-hydrostatic pump can boost the output flow of the hydraulic energy accumulator to the output pressure required by the hybrid energy storage unit through the energy provided by the storage battery, and the output flow is controlled and adjusted through the rotating speed of the motor; when the energy storage state of the hydraulic energy accumulator is high, the pressure is high, the electro-hydrostatic pump can reduce the output flow of the hydraulic energy accumulator to the output pressure required by the hybrid energy storage unit, redundant energy is stored in the storage battery through electric energy, and the output flow is controlled and adjusted through the rotating speed of the motor.

Similarly, when high-pressure hydraulic oil is stored, when the energy storage state of the hydraulic energy accumulator is low, the pressure is low, the static liquid pump reduces the pressure of the oil liquid input by the hybrid energy storage unit to the pressure of the hydraulic energy accumulator, redundant energy is stored in the storage battery by electric energy, and the output flow is controlled and adjusted by the rotating speed of the motor; when the energy storage state of the hydraulic energy accumulator is high, the pressure is high, the electro-hydrostatic pump utilizes the electric energy provided by the storage battery to boost the pressure of the oil liquid input by the hybrid energy storage unit to the pressure of the hydraulic energy accumulator, and the output flow is controlled and adjusted through the rotating speed of the motor. Therefore, active flow pressure control of the hybrid energy storage unit is realized.

Through active flow pressure regulation, the pressure range of the hydraulic accumulator can be expanded, the pre-charging pressure is reduced, and therefore the available capacity of the accumulator can be expanded. The energy density of the hydraulic accumulator is improved.

The invention has the beneficial effects that:

the charge and discharge of the hydraulic accumulator can not realize active regulation and control, and the energy density is lower. 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 electro-static liquid pump and the hydraulic accumulator are connected in series for use, on one hand, the oil liquid of the hydraulic accumulator is output after the pressure flow is regulated by the hydraulic pump motor, active hydraulic energy charging and discharging are realized, and the hydraulic accumulator can be better suitable for various working conditions; on the other hand, the boosting function of the electrostatic liquid pump enables the energy storage unit to continuously output energy when the pressure of the energy accumulator is low, so that the available volume of the energy accumulator is increased, and the energy density of the energy storage unit is increased.

Drawings

Fig. 1 is a schematic diagram of a series-type electro-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 hydraulic system comprises a hydraulic accumulator, 2, a storage battery, 3, a motor controller, 4, a motor, 5, a hydraulic pump motor, 6, a hydraulic oil tank, 7, a main hydraulic pump, 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 and 15 a second clutch.

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 hydraulic accumulator 1, a battery 2, a motor controller 3, an electric motor 4, and a hydraulic pump motor 5;

the storage battery 2 is electrically connected with the motor 4 through the motor controller 3, the output shaft of the motor 4 is mechanically connected with the output shaft of the hydraulic pump motor 5 synchronously, the hydraulic pump motor 5 is provided with two oil inlet and outlet ports, the first oil inlet and outlet port of the hydraulic pump motor 5 is communicated with the oil inlet and outlet port of the hydraulic accumulator 1, the second oil inlet and outlet port of the hydraulic pump motor 5 serves as the oil inlet and outlet port of the electro-hydraulic hybrid energy storage unit, the hydraulic pump motor 5 is driven by the motor, and the hydraulic pump motor 5 serves as an electro-static liquid pump. In specific implementation, an oil inlet and an oil outlet of the electro-hydraulic hybrid energy storage unit are communicated with a hydrostatic transmission loop or directly connected with oil inlets and oil outlets of hydraulic actuators such as a hydraulic cylinder and a hydraulic motor.

When the electro-hydraulic hybrid energy storage unit outputs energy in a high-pressure oil form, oil output by the hydraulic energy accumulator 1 is boosted or reduced in pressure by a hydraulic pump motor 5 driven by a motor 4 and then is output from an oil inlet and an oil outlet of the electro-hydraulic hybrid energy storage unit;

when the electro-hydraulic hybrid energy storage unit stores energy, oil input from an oil inlet and an oil outlet of the electro-hydraulic hybrid energy storage unit is input into the hydraulic energy accumulator 1 after being subjected to pressure reduction or pressure increase through the hydraulic pump motor 5.

The input and output flow of the electro-hydraulic hybrid energy storage unit, the input and output flow of the hydraulic pump motor 5 and the input and output energy of the hydraulic accumulator 1 satisfy the following relations:

Q＝Q_a＝Q_p

wherein Q is the oil inlet and outlet flow of the electro-hydraulic hybrid energy storage unit, and Q_aIs the flow rate, Q, of the hydraulic accumulator 1_pIs the flow rate of the hydraulic pump motor 5, i.e., the electro-hydrostatic pump.

The hydraulic pump motor 5 is a fixed displacement hydraulic pump motor or an electronic proportional control variable displacement hydraulic pump motor; the hydraulic pump motor 5 is a single hydraulic pump motor, or a combination of two or more hydraulic pump motors.

The hydraulic accumulator 1 is a combination of two or more hydraulic accumulators or a single hydraulic accumulator.

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

The power of the electro-hydraulic hybrid energy storage unit and the power of the hydraulic accumulator and the electro-static liquid pump have the following relations:

P＝P_a+P_p

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

When the energy storage state of the hydraulic energy accumulator is low, the pressure is low, the electric hydrostatic pump can drive the motor through the electric energy provided by the storage battery, the motor drives the hydraulic pump motor to work in a pump state, the output oil of the hydraulic energy accumulator is boosted to the output pressure required by the hybrid energy storage unit, and the output flow is controlled and adjusted through the rotating speed of the motor; when the hydraulic accumulator is in a high energy storage state, the pressure is high, the electro-hydrostatic pump can reduce the output flow of the hydraulic accumulator to the output pressure required by the hybrid energy storage unit, the hydraulic pump motor works in a motor state and in turn drives the motor to serve as a generator to generate electricity, and the redundant energy is stored in the storage battery by electric energy and is controlled and adjusted by the rotating speed of the motor.

Similarly, when high-pressure hydraulic oil is stored, when the energy storage state of the hydraulic energy accumulator is low, the pressure is low, the static liquid pump reduces the pressure of the oil liquid input by the hybrid energy storage unit to the pressure of the hydraulic energy accumulator, the hydraulic pump motor works in a motor state and in turn drives the motor to serve as a generator to generate electricity, redundant energy is stored in the storage battery as electric energy, and the output flow is controlled and adjusted through the rotating speed of the motor; when the energy storage state of the hydraulic energy accumulator is high, the pressure is high, the electro-hydrostatic pump drives the motor by using the electric energy provided by the storage battery, the motor drives the hydraulic pump motor to work in a pump state, the pressure of the oil pressure input by the hybrid energy storage unit is boosted to the pressure of the hydraulic energy accumulator, and the output flow is controlled and adjusted by the rotating speed of the motor. Therefore, active flow pressure control of the hybrid energy storage unit is realized.

Through active flow pressure regulation, the pressure range of the hydraulic accumulator can be expanded, the working pressure and the inflation pressure of the hydraulic accumulator are reduced, and therefore the available capacity of the accumulator can be expanded. The energy density of the hydraulic accumulator is improved.

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 a main hydraulic pump 7, a hydraulic motor 8, a vehicle final drive 9 and an engine 10;

an output shaft of an engine 10 is coaxially connected with an output shaft of a main hydraulic pump 7, two oil inlet and outlet ports of the main hydraulic pump 7 are respectively communicated with two oil inlet and outlet ports of a hydraulic motor 8, the main hydraulic pump 7, the hydraulic motor 8 and an oil circuit communicated with the main hydraulic pump 7 and the hydraulic motor 8 form a hydrostatic transmission loop, an output shaft of the hydraulic motor 8 is coaxially connected with a main speed reducer 9 of a vehicle, and an oil pipe connected between the main hydraulic pump 7 and the hydraulic motor 8 is communicated with the oil inlet and outlet ports of an electro-hydraulic hybrid energy storage unit.

The main power source of the hydrostatic transmission system is an engine 10, drives a main hydraulic pump 7, drives a hydraulic motor 8 through a hydrostatic transmission circuit, and drives vehicle wheels to run through a vehicle main speed reducer 9. The series electro-hydraulic hybrid energy storage unit can ensure that the hydraulic pressure of the hydrostatic transmission loop is in a 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 oil tank 6, 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;

an oil inlet and outlet of the hydraulic motor 8 is communicated with an oil inlet and outlet of the electro-hydraulic hybrid energy storage unit, the other oil inlet and outlet of the hydraulic motor 8 is communicated with the hydraulic oil tank 6, and the energy accumulator 1, the hydraulic pump motor 5, the hydraulic motor 8 and the hydraulic oil tank 6 form a hydrostatic transmission loop. 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 series-connection type electro-hydraulic hybrid energy storage unit can be converted into mechanical energy through the hydraulic motor 8 and then be gathered into the transmission shaft, and the redundant mechanical energy output by the engine 10 can be converted into hydraulic energy and stored in the electro-hydraulic hybrid 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 oil tank 6, 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;

an oil inlet and outlet of the hydraulic motor 8 is communicated with an oil inlet and outlet of the electro-hydraulic hybrid energy storage unit, the other oil inlet and outlet of the hydraulic motor 8 is communicated with the hydraulic oil tank 6, and the energy accumulator 1, the hydraulic pump motor 5, the hydraulic motor 8 and the hydraulic oil tank 6 form a hydrostatic transmission loop.

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 series-connection type electro-hydraulic hybrid energy storage unit can be converted into mechanical energy through the hydraulic motor 8 and then be gathered into the transmission shaft, and the redundant mechanical energy output by the engine 10 can be converted into hydraulic energy and stored in the electro-hydraulic 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 oil tank 6, a hydraulic motor 8, a vehicle main speed reducer 9, an engine 10, a gearbox 12, a meshing gear pair 13, a first clutch 14 and a second clutch 15;

an oil inlet and outlet of the hydraulic motor 8 is communicated with an oil inlet and outlet of the electro-hydraulic hybrid energy storage unit, the other oil inlet and outlet of the hydraulic motor 8 is communicated with the hydraulic oil tank 6, and the energy accumulator 1, the hydraulic pump motor 5, the hydraulic motor 8 and the hydraulic oil tank 6 form a hydrostatic transmission loop.

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 connected, braking energy is recovered while braking force is provided, mechanical energy on the transmission shaft is converted and stored into the series-connection type electro-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 oil tank 6, a hydraulic motor 8, a vehicle main speed reducer 9, an engine 10, a gearbox 12, a meshing gear pair 13, a first clutch 14 and a second clutch 15;

an oil inlet and outlet of the hydraulic motor 8 is communicated with an oil inlet and outlet of the electro-hydraulic hybrid energy storage unit, the other oil inlet and outlet of the hydraulic motor 8 is communicated with the hydraulic oil tank 6, and the energy accumulator 1, the hydraulic pump motor 5, the hydraulic motor 8 and the hydraulic oil tank 6 form a hydrostatic transmission loop.

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 connected, braking energy is recovered while braking force is provided, mechanical energy on the transmission shaft is converted and stored into the series-connection type electro-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.