阅读说明：本技术 一种并联式电液混合储能单元 (Parallel 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：本发明公开了一种并联式电液混合储能单元。包括蓄电池、电机控制器、电机、液压泵马达、液压蓄能器和液压油箱。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的同步机械连接,液压泵马达与液压蓄能器之间通过三通油管相连通。蓄电池储能具有高能量密度,液压蓄能器储能具有高功率密度但能量密度较低,本发明将液压蓄能器和电静液泵并联,通过电静液泵提供小功率长时间的液压能充放,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 a parallel-connection type electro-hydraulic hybrid energy storage unit. The hydraulic energy storage device comprises a storage battery, a motor controller, a motor, a hydraulic pump motor, a hydraulic energy accumulator and a hydraulic oil tank. 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, and the hydraulic pump motor is communicated with the hydraulic energy accumulator through a three-way oil pipe. The invention connects the hydraulic accumulator and the electro-hydrostatic pump in parallel, provides low-power long-time hydraulic energy charging and discharging through the electro-hydrostatic pump, and provides short-time high-power hydraulic energy charging and discharging through the hydraulic accumulator. Compared with the traditional hydraulic accumulator energy storage, the hybrid energy storage with high power density and high energy density can be realized.)

1. A parallel-connection type electro-hydraulic hybrid energy storage unit is characterized in that: the hydraulic control system comprises a hydraulic energy accumulator (1), a storage battery (2), a motor controller (3), a motor (4), a hydraulic pump motor (5) and a hydraulic oil tank (6);

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 communicated with the hydraulic energy accumulator (1) 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 with the oil inlet and outlet of the hydraulic energy accumulator (1), and a third connecting port of the three-way oil pipe is used as the oil inlet and outlet of the electro-hydraulic hybrid energy storage unit.

2. A parallel electro-hydraulic hybrid energy storage unit according to claim 1, characterized in that: when the electro-hydraulic hybrid energy storage unit outputs energy, oil output from the hydraulic oil tank (6) is boosted by a hydraulic pump motor (5) driven by a motor (4) and then output from an oil inlet and an oil outlet of the electro-hydraulic hybrid energy storage unit, or oil output from the hydraulic energy accumulator (1) is output from the oil inlet and the oil outlet of the electro-hydraulic hybrid energy storage unit, or the oil output from the hydraulic oil tank (6) and the hydraulic energy accumulator (1) is converged and then output from the oil inlet and the oil outlet of the electro-hydraulic hybrid energy storage unit;

when the electro-hydraulic hybrid energy storage unit stores energy, oil is directly input into the hydraulic energy accumulator (1) from the oil inlet and outlet of the electro-hydraulic hybrid energy storage unit for storage, or the oil is input into the hydraulic oil tank (6) from the oil inlet and outlet of the electro-hydraulic hybrid energy storage unit and then is input into the hydraulic oil pump (5), the hydraulic oil pump (5) drives the motor (4) to generate electricity, the energy is stored into the storage battery (2), or the oil is divided into two parts after passing through the oil inlet and outlet of the electro-hydraulic hybrid energy storage unit and is respectively input into the hydraulic oil tank (6) and the hydraulic energy accumulator (1).

3. A parallel electro-hydraulic hybrid energy storage unit according to claim 1, characterized in that: 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. A parallel electro-hydraulic hybrid energy storage unit according to claim 1, characterized in that: the hydraulic pump motor (5) is used as an electro-hydrostatic pump, and the power of the electro-hydraulic hybrid energy storage unit, the power of the hydraulic energy accumulator (1) and the power of the electro-hydrostatic pump meet 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.

5. A parallel electro-hydraulic hybrid energy storage unit according to claim 1, characterized in that: 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.

6. A parallel electro-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.

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

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

Technical Field

The invention relates to a hydraulic energy storage unit, in particular to a parallel 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 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 high energy density but low power density, and cannot provide high-power energy charging and discharging.

Disclosure of Invention

In order to solve the technical problems, the invention provides a parallel-type electro-hydraulic hybrid energy storage unit which can store and release hydraulic energy, combines energy storage of a hydraulic energy accumulator with high power density and energy storage of a storage battery with high energy density through energy distribution of an electro-static liquid pump and the hydraulic energy accumulator, and is integrated into an energy storage unit for use, so that the electro-hydraulic hybrid energy storage unit with high energy density and high power density is realized.

The technical scheme adopted by the invention is as follows:

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

the battery passes through the machine controller and is connected with the motor electricity, the output shaft of motor and the synchronous mechanical connection of hydraulic pump motor's output shaft, 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's 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 the first business turn over hydraulic fluid port of the mixed energy storage unit of electricity liquid.

When the electro-hydraulic hybrid energy storage unit outputs energy, oil output from the hydraulic oil tank is boosted by a hydraulic pump motor driven by a motor and then output from an oil inlet and an oil outlet of the electro-hydraulic hybrid energy storage unit, or oil output from the hydraulic energy accumulator is output from the oil inlet and the oil outlet of the electro-hydraulic hybrid energy storage unit, or oil output from the hydraulic oil tank and the hydraulic energy accumulator is converged by a three-way oil pipe and then output from the oil inlet and the oil outlet of the electro-hydraulic hybrid energy storage unit;

when the electro-hydraulic hybrid energy storage unit stores energy, oil is directly input into the hydraulic energy accumulator from the oil inlet and outlet of the electro-hydraulic hybrid energy storage unit for storage, or the oil is input into the hydraulic oil tank from the oil inlet and outlet of the electro-hydraulic hybrid energy storage unit and then is input into the hydraulic oil pump through the hydraulic pump motor, the hydraulic pump motor drives the motor to generate electricity, and the energy is stored into the storage battery, or the oil is divided into two parts after passing through the oil inlet and outlet of the electro-hydraulic hybrid energy storage unit and then is respectively input into the hydraulic oil tank and the hydraulic energy accumulator.

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 used as an electro-static liquid pump, and the power of the electro-hydraulic hybrid energy storage unit, the power of the hydraulic energy accumulator and the power of the electro-static liquid pump meet 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.

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

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 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 hydraulic energy accumulator is connected with the electro-hydrostatic pump in parallel, small-power long-time hydraulic energy charging and discharging is provided through the electro-hydrostatic pump, and short-time large-power hydraulic energy charging and discharging is provided through the hydraulic energy accumulator. The electro-hydrostatic pump can charge the hydraulic accumulator and release the energy once when the system needs high-power energy release.

The integrated design of the invention can reduce the volume of the energy storage unit and is convenient to be integrated into the design of the 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.

In addition, in the process of discharging energy from the hydraulic 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, the pressure reduction speed of the hydraulic energy accumulator is reduced, the energy output of the energy storage unit is enabled to be higher and adaptive to the pressure requirement, and the working stability is improved.

Drawings

FIG. 1 is a schematic diagram of a parallel type electro-hydraulic hybrid energy storage unit of the present invention.

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, 15 and 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 storage battery 2, a motor controller 3, an electric motor 4, a hydraulic pump motor 5, and a hydraulic oil tank 6;

the battery 2 is 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 communicated with the hydraulic accumulator 1 through a three-way oil pipe, 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 hydraulic oil tank 6 through an oil pipe, the second oil inlet and outlet port of the hydraulic pump motor 5 and the oil inlet and outlet port of the hydraulic accumulator 1 are respectively communicated with the first connecting port and the second connecting port of the three-way oil pipe, the third connecting port of the three-way oil pipe is used as the first oil inlet and outlet port of the electro-hydraulic hybrid energy storage unit, wherein, the hydraulic pump motor 5 is driven by the motor, and the hydraulic pump motor 5 is used as an electro-static liquid pump. In specific implementation, a first oil inlet and outlet of the hydraulic pump motor 5 is or is not used as a second oil inlet and outlet of the electro-hydraulic hybrid energy storage unit. The oil inlet and outlet of the electro-hydraulic hybrid energy storage unit are communicated with a hydrostatic transmission loop or directly communicated with the oil inlet and outlet of hydraulic actuators such as a hydraulic cylinder and a hydraulic motor.

The electro-hydraulic hybrid energy storage unit can realize the energy output and input storage in the form of high-pressure oil. When the electro-hydraulic hybrid energy storage unit outputs energy in a high-pressure oil form, oil output from the hydraulic oil tank 6 is boosted by the hydraulic pump motor 5 driven by the motor 4 and then output from the oil inlet and outlet of the electro-hydraulic hybrid energy storage unit, or oil output from high-pressure oil stored in the hydraulic energy accumulator 1 is output from the oil inlet and outlet of the electro-hydraulic hybrid energy storage unit, or high-pressure oil output from the hydraulic oil tank 6 and the hydraulic energy accumulator 1 is converged by a three-way oil pipe and then output from the oil inlet and outlet of the electro-hydraulic hybrid energy storage unit;

when the electro-hydraulic hybrid energy storage unit stores energy, high-pressure oil is directly input into the hydraulic energy accumulator 1 from an oil inlet and an oil outlet of the electro-hydraulic hybrid energy storage unit for storage, or the oil is input into the hydraulic oil tank 6 from the oil inlet and the oil outlet of the electro-hydraulic hybrid energy storage unit and then is input into the hydraulic oil pump 5, the hydraulic oil pump 5 drives the motor 4 to generate electricity, the energy is stored into the storage battery 2, or the oil is divided into two parts after passing through the oil inlet and the oil outlet of the electro-hydraulic hybrid energy storage unit and is respectively input into the hydraulic oil tank 6 and the hydraulic energy accumulator 1.

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 power of the electro-hydraulic hybrid energy storage unit, the power of the hydraulic energy accumulator and the power of the electro-hydrostatic pump meet 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_pThe power of the hydraulic pump motor 5, i.e. the electro-static liquid 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 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 a widely used engineering machine, and a common hydrostatic transmission system for walking and driving of small and medium-sized wheel loaders. The hydrostatic transmission system comprises a main hydraulic pump 7, a hydraulic motor 8, a vehicle main speed reducer 9 and an engine 10, wherein an output shaft of the engine 10 is coaxially connected with an output shaft of the 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 the 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, 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 main hydraulic pump 7 and the hydraulic motor 8 is communicated with a first oil inlet and outlet port of an 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 7 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 the vehicle main speed reducer 9 drives vehicle wheels to run. The parallel-type electro-hydraulic 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 and a second oil inlet and outlet of the electro-hydraulic hybrid energy storage unit, and the second oil inlet and outlet of the electro-hydraulic hybrid energy storage unit is not communicated with a hydraulic oil tank, namely, a hydraulic loop of the hydraulic pump motor 5 is a closed hydraulic loop. The hydraulic pump motor 5 and the hydraulic motor 8 form a hydrostatic transmission circuit with an oil passage communicating therewith. 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 parallel type electro-hydraulic hybrid energy storage unit can be converted into mechanical energy through the hydraulic motor 8 and then is gathered into the transmission shaft, and the redundant mechanical energy output by the engine 10 can be converted into the 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 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 and a second oil inlet and outlet of the electro-hydraulic hybrid energy storage unit, and the second oil inlet and outlet of the electro-hydraulic hybrid energy storage unit is not communicated with a hydraulic oil tank, namely, a hydraulic loop of the hydraulic pump motor 5 is a closed hydraulic loop. The hydraulic pump motor 5 and the hydraulic motor 8 form a hydrostatic transmission circuit with an oil passage communicating therewith.

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 parallel type electro-hydraulic hybrid energy storage unit can be converted into mechanical energy through the hydraulic motor 8 and then is gathered into the transmission shaft, and the redundant mechanical energy output by the engine 10 can be converted into the 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 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 and a second oil inlet and outlet of the electro-hydraulic hybrid energy storage unit, and the second oil inlet and outlet of the electro-hydraulic hybrid energy storage unit is not communicated with a hydraulic oil tank, namely, a hydraulic loop of the hydraulic pump motor 5 is a closed hydraulic loop. The hydraulic pump motor 5 and the hydraulic motor 8 form a hydrostatic transmission circuit with an oil passage communicating therewith.

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 parallel-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 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 and a second oil inlet and outlet of the electro-hydraulic hybrid energy storage unit, and the second oil inlet and outlet of the electro-hydraulic hybrid energy storage unit is not communicated with a hydraulic oil tank, namely, a hydraulic loop of the hydraulic pump motor 5 is a closed hydraulic loop. The hydraulic pump motor 5 and the hydraulic motor 8 form a hydrostatic transmission circuit with an oil passage communicating therewith.

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 parallel-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.