阅读说明：本技术 一种高效机液耦合式液压变压器 (Efficient mechanical-hydraulic coupling type hydraulic transformer ) 是由 周连佺 张楚 薄晓楠 刘强 瞿炜炜 于 2020-05-13 设计创作，主要内容包括：一种高效机液耦合式液压变压器,包括大流量液压泵/马达(1)、小流量液压泵/马达(2)、一号换向阀(3)、二号换向阀(4)、三号换向阀(5)、四号换向阀(6)和油箱,大流量液压泵/马达(1)和小流量液压泵/马达(2)同轴刚性连接。本发明的机液耦合液压变压器将一部分液压能转换为机械能,再将机械能与液压能耦合实现压力的改变,因此能量传递效率相较以往有很大的提升。机液耦合液压变压器配有四个换向阀,通过换向阀的组合可以使得两个液压泵/马达灵活转变工况,并且还可以将其中一个液压泵/马达换成小排量液压泵/马达而不改变原本功能,使得能量损失与成本都进一步下降,变压效率相较以往液压变压器有很大的提升。(A high-efficiency mechanical-hydraulic coupling type hydraulic transformer comprises a large-flow hydraulic pump/motor (1), a small-flow hydraulic pump/motor (2), a first reversing valve (3), a second reversing valve (4), a third reversing valve (5), a fourth reversing valve (6) and an oil tank, wherein the large-flow hydraulic pump/motor (1) and the small-flow hydraulic pump/motor (2) are coaxially and rigidly connected. The mechanical-hydraulic coupling hydraulic transformer converts a part of hydraulic energy into mechanical energy, and then couples the mechanical energy with the hydraulic energy to change the pressure, so that the energy transfer efficiency is greatly improved compared with the prior art. The mechanical-hydraulic coupling hydraulic transformer is provided with four reversing valves, the two hydraulic pumps/motors can flexibly change working conditions through the combination of the reversing valves, one hydraulic pump/motor can be changed into a small-displacement hydraulic pump/motor without changing the original function, energy loss and cost are further reduced, and transformation efficiency is greatly improved compared with that of the conventional hydraulic transformer.)

1. A high-efficiency mechanical-hydraulic coupling type hydraulic transformer comprises a large-flow hydraulic pump/motor (1), a small-flow hydraulic pump/motor (2), a first reversing valve (3), a second reversing valve (4), a third reversing valve (5), a fourth reversing valve (6) and an oil tank, wherein the large-flow hydraulic pump/motor (1) and the small-flow hydraulic pump/motor (2) are coaxially and rigidly connected;

each reversing valve is provided with three oil ports which are respectively an oil inlet/outlet port P, an oil return port T connected with an oil tank and a working oil port A connected with an execution element, and the working oil port A is communicated with the oil inlet/outlet port P when the reversing valve is electrified; when the reversing valve is powered off, the working oil port A is communicated with the oil return port T;

the oil inlet and outlet of the large-flow hydraulic pump/motor (1) are respectively connected with the working oil port 3A of the first reversing valve (3) and the working oil port 5A of the third reversing valve (5); an oil inlet and an oil outlet of the small-flow hydraulic pump/motor (2) are connected with a working oil port 4A of the second reversing valve (4) and a working oil port 6A of the third reversing valve (6); the oil inlet and outlet P ports of the first reversing valve (3) and the second reversing valve (4) are connected and then connected with a system oil supply (7), and the oil return T port is connected and connected into an oil tank; the third reversing valve (5) and the fourth reversing valve (6) are connected with an oil inlet P port and an oil outlet P port and then connected with a load (8), and an oil return T port is connected and connected into an oil tank;

when the hydraulic transformer is in a boosting working condition, system oil supply (7) simultaneously supplies oil to the large-flow hydraulic pump/motor (1) and the small-flow hydraulic pump/motor (2), one of the large-flow hydraulic pump/motor (1) and the small-flow hydraulic pump/motor (2) is used as a pump working condition to convey hydraulic oil to a load (8), the other one is used as a motor working condition to convert hydraulic energy into mechanical energy, torque is conveyed to the hydraulic pump through a shaft, so that the output pressure of an oil outlet of the hydraulic pump is increased, and the hydraulic transformer realizes a boosting function;

when the hydraulic transformer is in a pressure reduction working condition, the system oil supply (7) only supplies oil to one of the large-flow hydraulic pump/motor (1) and the small-flow hydraulic pump/motor (2) independently, the hydraulic pump/motor supplied with oil is in a motor working condition at the moment, the oil inlet of the other hydraulic pump/motor is connected with the oil tank to serve as a hydraulic pump working condition, the hydraulic pump is connected with the oil outlet of the hydraulic motor and supplies oil to the load (8), the hydraulic motor converts input hydraulic energy into mechanical energy, torque is transmitted to the hydraulic pump through a shaft, the output pressure of the hydraulic pump is the same as the output pressure of the hydraulic motor and supplies oil to the load (8) at the same time, the output pressure is lower than the input pressure at the moment, and the hydraulic transformer.

2. The method of boosting an electromechanically-hydraulically-coupled hydraulic transformer of claim 1, wherein the method is one of:

the pressure and the flow of the oil supply (7) of the metering system are P₀、Q₀(ii) a The pressure and flow rate of the oil supplied to the load (8) by the transformer device are P₃、Q₃(ii) a The pressure and the flow of an oil inlet of the high-flow hydraulic pump/motor (1) are P₁、Q₁Pressure and flow rate of oil outlet is P₁a、Q₁a; the pressure and the flow of an oil inlet of the small-flow hydraulic pump/motor (2) are P₂、Q₂Pressure and flow rate of oil outlet is P₂a、Q₂a；

The method comprises the following steps:

the first reversing valve (3), the second reversing valve (4) and the third reversing valve (5) are powered on, the fourth reversing valve (6) is powered off, the large-flow hydraulic pump/motor (1) is in a hydraulic pump working condition, and the small-flow hydraulic pump/motor (2) is in a hydraulic motor working condition; oil inlets of the large-flow hydraulic pump/motor (1) and the small-flow hydraulic pump/motor (2) are connected, oil is supplied by system oil supply (7), an oil outlet of the large-flow hydraulic pump/motor (1) is connected with a load (8), and an oil outlet of the small-flow hydraulic pump/motor (2) is connected with an oil tank;

oil inlet pressure P of large-flow hydraulic pump/motor (1) and small-flow hydraulic pump/motor (2)₁＝P₀、P₂＝P₀(ii) a Oil outlet pressure P of large-flow hydraulic pump/motor (1) and small-flow hydraulic pump/motor (2)₁a＝P₃、P₂a＝0；

Output torque of small flow hydraulic pump/motor (2)V₂Is the displacement of the small-flow hydraulic pump/motor (2); input torque of large flow hydraulic pump/motor (1)V₁The displacement of the large-flow hydraulic pump/motor (1); the output torque of the small flow hydraulic pump/motor (2) is equal to the input torque of the large flow hydraulic pump/motor (1),then transformation ratio

The second method comprises the following steps:

the first reversing valve (3), the second reversing valve (4) and the fourth reversing valve (6) are powered on, the third reversing valve (5) is powered off, the large-flow hydraulic pump/motor (1) is in a hydraulic motor working condition, and the small-flow hydraulic pump/motor (2) is in a hydraulic pump working condition;

oil is supplied by a system oil supply (7), working oil is supplied by a small-flow hydraulic pump/motor (2), and an oil outlet of a large-flow hydraulic pump/motor (1) is connected with an oil tank; oil inlet pressure P of large-flow hydraulic pump/motor (1) and small-flow hydraulic pump/motor (2)₁＝P₀、P₂＝P₀(ii) a Oil outlet pressure P of large-flow hydraulic pump/motor (1) and small-flow hydraulic pump/motor (2)₁a＝0、P₂a＝P₃；

Output torque of large flow hydraulic pump/motor (1)V₁The displacement of the large-flow hydraulic pump/motor (1); input torque of small flow hydraulic pump/motor (2)V₂Is the displacement of the small-flow hydraulic pump/motor (2); the output torque of the small flow hydraulic pump/motor (2) is equal to the input torque of the large flow hydraulic pump/motor (1),then transformation ratio

3. Method according to claim 2, characterized in that in method one, the maximum displacement of the small flow hydraulic pump/motor (2) is 2/3, i.e. V, of the large flow hydraulic pump/motor (1)_2MAX＝2/3V_1MAXAdjusting the displacement of the large-flow hydraulic pump/motor (1) to V_1MAXWhen V is₂＝0～V_2MAXWhen the transformation ratio lambda is 1-5/3, lambda follows V₂Increasing linearly.

4. Method according to claim 2, characterized in that in the second method, the maximum displacement of the small hydraulic pump/motor (2) is 2/3, i.e. V, of the large hydraulic pump/motor (1)_2MAX＝2/3V_1MAXThe displacement of the small hydraulic pump/motor (2) is adjusted to V_2MAXWhen V is₁＝4/9V_1MAX～V_1MAXWhen λ is 5/3-5/2, λ follows V₁Increasing linearly.

5. Method according to claim 2, characterized in that in the second method, the maximum displacement of the small hydraulic pump/motor (2) is that of the large hydraulic pump/motor (1)2/3, i.e. V_2MAX＝2/3V_1MAXAdjusting the large flow hydraulic pump/motor (1) to V_1MAXWhen V is₂＝V_2MAXWhen the voltage is about 0, the transformation ratio lambda is 5/2 to infinity, and lambda is dependent on V₂The inverse ratio increases.

6. The method for decompressing an electromechanically-hydraulically-coupled hydraulic transformer according to claim 1, characterized in that it is one of the following methods:

the pressure and the flow of the oil supply (7) of the metering system are P₀、Q₀(ii) a The pressure and flow rate of the oil supplied to the load (8) by the transformer device are P₃、Q₃(ii) a The pressure and the flow of an oil inlet of the high-flow hydraulic pump/motor (1) are P₁、Q₁Pressure and flow rate of oil outlet is P₁a、Q₁a; the pressure and the flow of an oil inlet of the small-flow hydraulic pump/motor (2) are P₂、Q₂Pressure and flow rate of oil outlet is P₂a、Q₂a；

The method comprises the following steps:

the first reversing valve (3), the third reversing valve (5) and the fourth reversing valve (6) are powered on, the second reversing valve (4) is powered off, the large-flow hydraulic pump/motor (1) is in a hydraulic motor working condition, and the small-flow hydraulic pump/motor (2) is in a hydraulic pump working condition; oil is conveyed to an oil inlet of a large-flow hydraulic pump/motor (1) by a system oil supply (7), oil outlets of the large-flow hydraulic pump/motor (1) and a small-flow hydraulic pump/motor (2) are connected and supply oil to a load (8) together, and an oil suction port of the small-flow hydraulic pump/motor (2) is connected with an oil tank; oil inlet pressure P of large-flow hydraulic pump/motor (1) and small-flow hydraulic pump/motor (2)₁＝P₀、P₂0; oil outlet pressure P of large-flow hydraulic pump/motor (1) and small-flow hydraulic pump/motor (2)₁a＝P₃、P₂a＝P₃；

Output torque of large flow hydraulic pump/motor (1)V₁The displacement of the large-flow hydraulic pump/motor (1); input torque of small flow hydraulic pump/motor (2)V₂Is the displacement of the small-flow hydraulic pump/motor (2); because the large-flow hydraulic pump/motor (1) and the small-flow hydraulic pump/motor (2) are coaxially connected, the output torque of the large-flow hydraulic pump/motor (1) and the input torque of the small-flow hydraulic pump/motor (2) are equal,then transformation ratio

The second method comprises the following steps:

the second reversing valve (4), the third reversing valve (5) and the fourth reversing valve (6) are powered on, the first reversing valve (3) is powered off, the large-flow hydraulic pump/motor (1) is in a hydraulic pump working condition, and the small-flow hydraulic pump/motor (2) is in a hydraulic motor working condition; oil is conveyed to an oil inlet of a small-flow hydraulic pump/motor (2) by a system oil supply (7), oil outlets of a large-flow hydraulic pump/motor (1) and the small-flow hydraulic pump/motor (2) are connected and supply oil to a load (8) together, and an oil suction port of the large-flow hydraulic pump/motor (1) is connected with an oil tank; oil inlet pressure P of large-flow hydraulic pump/motor (1) and small-flow hydraulic pump/motor (2)₁＝0、P₂＝P₀(ii) a Oil outlet pressure P of large-flow hydraulic pump/motor (1) and small-flow hydraulic pump/motor (2)₁a＝P₃、P₂a＝P₃；

Output torque of small flow hydraulic pump/motor (2)V₂Is the displacement of the small-flow hydraulic pump/motor (2); input torque of large flow hydraulic pump/motor (1)V₂The displacement of the small-flow hydraulic pump (1); output torque of large flow hydraulic pump/motor (1) and small flow hydraulic pump/motor(2) Are equal to each other in the input torque of (c),then transformation ratio

7. Method according to claim 5, characterized in that in method one, the maximum displacement of the small flow hydraulic pump/motor (2) is 2/3, i.e. V, of the large flow hydraulic pump/motor (1)_2MAX＝2/3V_1MAXThe discharge capacity of the large-flow hydraulic pump/motor (1) is adjusted to V_1MAXWhen V is₂＝0～V_2MAXWhen λ is 1-3/5, λ follows V₂The inverse ratio decreases.

8. The method according to claim 5, characterized in that in the second method, the maximum displacement of the small flow hydraulic pump/motor (2) is 2/3 (V) of the large flow hydraulic pump/motor (1)_2MAX＝2/3V_1MAXAdjusting the displacement of the small flow hydraulic pump/motor (2) to V_2MAXWhen V is₁＝4/9V_1MAX～V_1MAXWhen λ is 3/5-2/5, λ follows V₁The inverse ratio decreases.

9. The method according to claim 5, characterized in that in the second method, the maximum displacement of the small flow hydraulic pump/motor (2) is 2/3 (V) of the large flow hydraulic pump/motor (1)_2MAX＝2/3V_1MAXThe discharge capacity of the large-flow hydraulic pump/motor (1) is adjusted to V_1MAXWhen V is₂＝V_2MAXWhen the value is about 0, lambda is 2/5-0, and lambda follows V₂The inverse ratio decreases.

Technical Field

The invention relates to the field of hydraulic transmission, in particular to the field of hydraulic engineering machinery, and particularly relates to a high-efficiency mechanical-hydraulic coupling type hydraulic transformer.

Background

The constant-pressure network secondary regulation technology is a novel hydrostatic transmission technology developed in recent years, and in the secondary regulation hydrostatic transmission, a plurality of unrelated hydraulic elements can obtain energy from a constant-pressure network without loss, so that the flexibility and the efficiency of a hydraulic system are improved, and the recovery and the reutilization of system braking energy and heavy potential energy are realized. The main reason why it has not found widespread use is the lack of a hydraulic element that efficiently transmits hydraulic energy.

As a novel flow and pressure conversion element, the hydraulic transformer can theoretically transmit hydraulic energy without throttling loss. The traditional hydraulic transformer structurally connects two axial plunger pumps with equal displacement and an axial plunger motor together through a rigid shaft, controls the transformation ratio of the transformer by changing the displacement of the pumps and the displacement of the motors, and can change the functions of the pumps and the motors along with the transformation of different working conditions, so that the hydraulic transformer can transform voltage in two directions, and the recovery of system energy is realized.

However, the hydraulic transformer has some problems, mainly low efficiency, and as a hydraulic component aiming at improving the efficiency of a hydraulic system, since the energy is transmitted by two plunger pumps/motors, and the plunger pumps/motors have certain volumetric efficiency and mechanical efficiency loss, the whole hydraulic transformer still has the problems of large leakage amount, large energy loss and the like, so that the hydraulic system does not achieve the expected effect, and is popularized at the present stage.

Disclosure of Invention

The invention provides a hydraulic pressure device, which is characterized in that two different hydraulic pumps/motors with one large flow and one small flow are connected in series, so that inlet and outlet oil paths of the two hydraulic pumps/motors are controlled by an independent reversing valve, the connection of the inlet and outlet oil paths can be freely switched between an oil tank and an oil supply/load, and bidirectional pressurization or decompression is realized.

Specifically, the invention provides a high-efficiency mechanical-hydraulic coupling type hydraulic transformer which comprises a large-flow hydraulic pump/motor, a small-flow hydraulic pump/motor, a first reversing valve, a second reversing valve, a third reversing valve, a fourth reversing valve and an oil tank, wherein the large-flow hydraulic pump/motor and the small-flow hydraulic pump/motor are coaxially and rigidly connected;

each reversing valve is provided with three oil ports which are respectively an oil inlet/outlet port P, an oil return port T connected with an oil tank and a working oil port A connected with an execution element, and the working oil port A is communicated with the oil inlet/outlet port P when the reversing valve is electrified; when the reversing valve is powered off, the working oil port A is communicated with the oil return port T;

the oil inlet and outlet of the large-flow hydraulic pump/motor are respectively connected with the working oil port 3A of the first reversing valve and the working oil port 5A of the third reversing valve; the oil inlet and outlet of the small-flow hydraulic pump/motor are connected with the working oil port 4A of the second reversing valve and the working oil port 6A of the third reversing valve; the oil inlet and outlet P ports of the first reversing valve and the second reversing valve are connected and then connected with a system oil supply, and the oil return T port is connected and connected into an oil tank; the third reversing valve and the fourth reversing valve are connected with an oil inlet P port and then connected with a load, and an oil return T port is connected and connected into an oil tank;

when the hydraulic transformer is in a boosting working condition, the system supplies oil to simultaneously supply oil to the large-flow hydraulic pump/motor and the small-flow hydraulic pump/motor, one of the large-flow hydraulic pump/motor and the small-flow hydraulic pump/motor is used as a pump working condition to convey hydraulic oil to a load, the other one is used as a motor working condition to convert hydraulic energy into mechanical energy, and torque is conveyed to the hydraulic pump through a shaft, so that the output pressure of an oil outlet of the hydraulic pump is increased, and the hydraulic transformer realizes the boosting function;

when the hydraulic transformer is in a pressure reduction working condition, system oil supply only supplies oil to one of a large-flow hydraulic pump/motor and a small-flow hydraulic pump/motor independently, the hydraulic pump/motor supplied with oil is in a motor working condition, an oil inlet of the other hydraulic pump/motor is connected with an oil tank to serve as a hydraulic pump working condition, the hydraulic pump is connected with an oil outlet of the hydraulic motor and supplies oil to a load simultaneously, the hydraulic motor converts input hydraulic energy into mechanical energy, torque is transmitted to the hydraulic pump through a shaft, the output pressure of the hydraulic pump is the same as the output pressure of the hydraulic motor and supplies oil to the load simultaneously, the output pressure is lower than the input pressure, and the hydraulic transformer achieves a pressure reduction function.

The invention also provides a pressurization method of the mechanical-hydraulic coupling type hydraulic transformer, which is one of the following methods:

the pressure and the flow of the oil supply of the metering system are P₀、Q₀(ii) a The pressure and flow of the oil supplied to the load by the transformer device are P₃、Q₃(ii) a High flowThe pressure and the flow of an oil inlet of the hydraulic metering pump/motor are P₁、Q₁Pressure and flow rate of oil outlet is P₁a、Q₁a; the pressure and the flow of an oil inlet of the small-flow hydraulic pump/motor are P₂、Q₂Pressure and flow rate of oil outlet is P₂a、Q₂a；

The method comprises the following steps:

the first reversing valve, the second reversing valve and the third reversing valve are electrified, the fourth reversing valve is not electrified, the large-flow hydraulic pump/motor is under the working condition of a hydraulic pump, and the small-flow hydraulic pump/motor is under the working condition of a hydraulic motor; the oil inlets of the large-flow hydraulic pump/motor and the small-flow hydraulic pump/motor are connected, oil is supplied by a system, the oil outlet of the large-flow hydraulic pump/motor is connected with a load, and the oil outlet of the small-flow hydraulic pump/motor is connected with an oil tank;

oil inlet pressure P of large-flow hydraulic pump/motor and small-flow hydraulic pump/motor₁＝P₀、P₂＝P₀(ii) a Oil outlet pressure P of large-flow hydraulic pump/motor and small-flow hydraulic pump/motor₁a＝P₃、P₂a＝0；

Output torque of small flow hydraulic pump/motorV₂Is the displacement of a small flow hydraulic pump/motor; input torque for high flow hydraulic pump/motorV₁The displacement of a large-flow hydraulic pump/motor; the output torque of the small flow hydraulic pump/motor and the input torque of the large flow hydraulic pump/motor are equal,then transformation ratio

The second method comprises the following steps:

the first reversing valve, the second reversing valve and the fourth reversing valve are electrified, the third reversing valve is not electrified, the large-flow hydraulic pump/motor is in a hydraulic motor working condition, and the small-flow hydraulic pump/motor is in a hydraulic pump working condition;

oil is supplied by a system, working oil is supplied by a small-flow hydraulic pump/motor, and an oil outlet of a large-flow hydraulic pump/motor is connected with an oil tank; oil inlet pressure P of large-flow hydraulic pump/motor and small-flow hydraulic pump/motor₁＝P₀、P₂＝P₀(ii) a Oil outlet pressure P of large-flow hydraulic pump/motor and small-flow hydraulic pump/motor₁a＝0、P₂a＝P₃；

Output torque of high flow hydraulic pump/motorV₁The displacement of a large-flow hydraulic pump/motor; input torque for small flow hydraulic pump/motorV₂Is the displacement of a small flow hydraulic pump/motor; the output torque of the small flow hydraulic pump/motor and the input torque of the large flow hydraulic pump/motor are equal,then transformation ratio

Further, in the first method, the maximum displacement of the small-flow hydraulic pump/motor is 2/3, namely V, of the large-flow hydraulic pump/motor_2MAX＝2/3V_1MAXAdjusting the discharge capacity of the large-flow hydraulic pump/motor to V_1MAXWhen V is₂＝0～V_2MAXWhen the transformation ratio lambda is 1-5/3, lambda follows V₂Increasing linearly.

Further, in the second method, the maximum displacement of the small hydraulic pump/motor is 2/3, namely V, of the large hydraulic pump/motor_2MAX＝2/3V_1MAXAdjusting the displacement of the small hydraulic pump/motor to V_2MAXWhen V is₁＝4/9V_1MAX～V_1MAXWhen λ is 5/3-5/2, λ follows V₁Increasing linearly.

Further, in the second method, the maximum displacement of the small hydraulic pump/motor is 2/3, namely V, of the large hydraulic pump/motor_2MAX＝2/3V_1MAXAdjusting the large flow hydraulic pump/motor to V_1MAXWhen V is₂＝V_2MAXWhen the voltage is about 0, the transformation ratio lambda is 5/2 to infinity, and lambda is dependent on V₂The inverse ratio increases.

The invention also provides a decompression method of the mechanical-hydraulic coupling type hydraulic transformer, which is one of the following methods:

the pressure and the flow of the oil supply of the metering system are P₀、Q₀(ii) a The pressure and flow of the oil supplied to the load by the transformer device are P₃、Q₃(ii) a The pressure and the flow of an oil inlet of the high-flow hydraulic pump/motor are P₁、Q₁Pressure and flow rate of oil outlet is P₁a、Q₁a; the pressure and the flow of an oil inlet of the small-flow hydraulic pump/motor are P₂、Q₂Pressure and flow rate of oil outlet is P₂a、Q₂a；

The method comprises the following steps:

the first reversing valve, the third reversing valve and the fourth reversing valve are electrified, the second reversing valve is not electrified, the large-flow hydraulic pump/motor is in a hydraulic motor working condition, and the small-flow hydraulic pump/motor is in a hydraulic pump working condition; oil is supplied by a system and is conveyed to an oil inlet of a large-flow hydraulic pump/motor, oil outlets of the large-flow hydraulic pump/motor and a small-flow hydraulic pump/motor are connected to supply oil to a load together, and an oil suction port of the small-flow hydraulic pump/motor is connected with an oil tank; oil inlet pressure P of large-flow hydraulic pump/motor and small-flow hydraulic pump/motor₁＝P₀、P₂0; oil outlet pressure P of large-flow hydraulic pump/motor and small-flow hydraulic pump/motor₁a＝P₃、P₂a＝P₃；

Output torque of high flow hydraulic pump/motorV₁Is largeDisplacement of the flow hydraulic pump/motor; input torque for small flow hydraulic pump/motorV₂Is the displacement of a small flow hydraulic pump/motor; because the large-flow hydraulic pump/motor and the small-flow hydraulic pump/motor are coaxially connected, the output torque of the large-flow hydraulic pump/motor and the input torque of the small-flow hydraulic pump/motor are equal,then transformation ratio

The second method comprises the following steps:

the second reversing valve, the third reversing valve and the fourth reversing valve are electrified, the first reversing valve is not electrified, the large-flow hydraulic pump/motor is under the working condition of a hydraulic pump, and the small-flow hydraulic pump/motor is under the working condition of a hydraulic motor; oil is delivered to an oil inlet of a small-flow hydraulic pump/motor by system oil supply, oil outlets of a large-flow hydraulic pump/motor and the small-flow hydraulic pump/motor are connected and supply oil to a load together, and an oil suction port of the large-flow hydraulic pump/motor is connected with an oil tank; oil inlet pressure P of large-flow hydraulic pump/motor and small-flow hydraulic pump/motor₁＝0、P₂＝P₀(ii) a Oil outlet pressure P of large-flow hydraulic pump/motor and small-flow hydraulic pump/motor₁a＝P₃、P₂a＝P₃；

Output torque of small flow hydraulic pump/motorV₂Is the displacement of a small flow hydraulic pump/motor; input torque for high flow hydraulic pump/motorV₂The displacement is the displacement of a small-flow hydraulic pump; the output torque of the large flow hydraulic pump/motor and the input torque of the small flow hydraulic pump/motor are equal,then transformation ratio

Further, in the first method, the maximum displacement of the small-flow hydraulic pump/motor is 2/3, namely V, of the large-flow hydraulic pump/motor_2MAX＝2/3V_1MAXAdjusting the discharge capacity of the large-flow hydraulic pump/motor to V_1MAXWhen V is₂＝0～V_2MAXWhen λ is 1-3/5, λ follows V₂The inverse ratio decreases.

Further, in the second method, the maximum displacement of the small-flow hydraulic pump/motor is 2/3, namely V, of the large-flow hydraulic pump/motor_2MAX＝2/3V_1MAXAdjusting the displacement of the small-flow hydraulic pump/motor to V_2MAXWhen V is₁＝4/9V_1MAX～V_1MAXWhen λ is 3/5-2/5, λ follows V₁The inverse ratio decreases.

Further, in the second method, the maximum displacement of the small-flow hydraulic pump/motor is 2/3, namely V, of the large-flow hydraulic pump/motor_2MAX＝2/3V_1MAXAdjusting the discharge capacity of the large-flow hydraulic pump/motor to V_1MAXWhen V is₂＝V_2MAXWhen the value is about 0, lambda is 2/5-0, and lambda follows V₂The inverse ratio decreases. .

Compared with the prior art, the invention has the beneficial effects that:

the energy transmission of the mechanical-hydraulic coupling hydraulic transformer is different from the traditional mode of hydraulic energy-mechanical energy-hydraulic energy, but converts a part of hydraulic energy into mechanical energy, and then couples the mechanical energy with the hydraulic energy to change the pressure, so that the energy transmission efficiency is greatly improved compared with the prior art. The mechanical-hydraulic coupling hydraulic transformer is provided with four reversing valves, the two hydraulic pumps/motors can flexibly change working conditions through the combination of the reversing valves, one hydraulic pump/motor can be changed into a small-displacement hydraulic pump/motor without changing the original function, energy loss and cost are further reduced, and transformation efficiency is greatly improved compared with that of the conventional hydraulic transformer.

Drawings

FIG. 1 is a schematic diagram of forward transformation of a mechanical-hydraulic coupling hydraulic transformer

FIG. 2 is a schematic diagram of a forward supercharging condition

FIG. 3 is a schematic diagram of two operating conditions of forward supercharging

FIG. 4 is a schematic diagram of a forward pressure reduction operating mode

FIG. 5 is a schematic diagram of two working conditions of forward pressure reduction

In fig. 1: 1. high flow hydraulic pumps/motors; 2. a small flow hydraulic pump/motor; 3. a first reversing valve; 4. a second reversing valve; 5. a third reversing valve; 6. a fourth reversing valve; 7. supplying oil to the system; 8. and (4) loading.

The specific implementation mode is as follows:

the technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.