Hybrid hydraulic system and aerial lift

Abstract

The application discloses a kind of hybrid hydraulic system and aerial work platform, comprising: engine, motor and gear pump, engine and motor can be separated and can be connected, gear pump is connected with motor;High-pressure oil circuit, which is connected with the discharge port of gear pump;Proportional valve, its oil inlet is connected with high-pressure oil circuit;Pilot operated directional control valve, the oil inlet of pilot operated directional control valve is connected with high-pressure oil circuit, and the oil return of pilot operated directional control valve is connected with low-pressure oil return circuit;Control oil circuit, which is arranged between the control oil port of pilot operated directional control valve and the working oil port of proportional valve, control oil circuit is provided with check valve, and the oil inlet of check valve is connected with the working oil port of proportional valve;Switch valve, which is arranged between high-pressure oil circuit and the oil inlet of pilot operated directional control valve, when engine is not working, switch valve is closed;When engine works, switch valve is opened.Influence electric mode is not reduced under diesel mode, and the outlet pressure of gear pump is reduced, energy loss is reduced, power generation rate is improved, and the service life of gear pump is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydraulic systems, and more particularly to a hybrid hydraulic system. In addition, the present application also relates to an aerial work platform including the above-mentioned hybrid hydraulic system. BACKGROUND

[0002] In order to respond to the development mainstream of energy saving and environmental protection, and to adapt to the demand of complex working conditions, hybrid aerial work platforms appear in the market. The hybrid aerial work platform adopts a gear pump hydraulic system with dual power of engine and motor, that is, the engine and the motor are connected in series through a clutch, the motor is connected with the gear pump, and the gear pump is driven to rotate by the rotation of the motor, thereby providing a power oil source for the entire hydraulic system. The hybrid aerial work platform has two working modes, namely electric mode and diesel mode, and the two working modes are controlled and switched by a swing switch (or a knob switch) on the control panel.

[0003] When the hybrid aerial work platform is in electric mode, the engine and the motor are disconnected, the motor rotates under the power supply of the battery, and in turn drives the gear pump to rotate to supply hydraulic oil; at this time, the speed of each actuator in the hydraulic system is controlled by the motor speed, that is, by controlling the motor speed, the flow rate output by the gear pump is controlled, and in turn the speed of each actuator is controlled.

[0004] When the hybrid aerial work platform is in diesel mode, the engine and the motor are coupled and connected through the clutch, at this time, the motor is used as a generator, the engine is used as a power source, drives the generator (motor) to generate electricity, and drives the gear pump to rotate to supply hydraulic oil; under this working condition, since the engine rotates at a fixed speed, the flow rate output by the gear pump at a fixed speed is fixed, and since the flow rates required by each actuator are inconsistent, only the flow rate output by the gear pump can be the maximum required flow rate. This makes the flow rate output by the gear pump greater than the actual demand flow rate of some actuators, and the excess flow rate forms a high pressure overflow, which on the one hand makes the gear pump work in a high pressure state for a long time, resulting in a significant reduction in the service life of the gear pump; on the other hand, since the power required to drive the gear pump to rotate is proportional to the outlet pressure of the gear pump, when the outlet pressure of the gear pump is large, a lot of power is wasted; further, since the engine rotates at a fixed speed when the hybrid aerial work platform is in diesel mode, the excess power is used for the generator (motor) to generate electricity, and since the gear pump causes a lot of energy waste, the efficiency of the engine for power generation is very low.

[0005] To sum up, how to provide a kind of hybrid hydraulic system, while not affecting the working condition of aerial work platform in electric mode, reduce the outlet pressure of gear pump of aerial work platform in diesel mode, is the urgent problem of the present field skilled personnel. SUMMARY

[0006] Therefore, the purpose of the present application is to provide a kind of hybrid hydraulic system, which can reduce the outlet pressure of gear pump in diesel mode, while not affecting the normal operation of electric mode, so as to reduce energy loss, improve power generation rate, and prolong the service life of gear pump.

[0007] Another purpose of the present application is to provide a kind of aerial work platform comprising the above-mentioned hybrid hydraulic system, which has small energy loss, high power generation rate and long service life of gear pump.

[0008] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0009] A kind of hybrid hydraulic system, comprising:

[0010] Engine, motor and gear pump, the engine is separable and connectable with the motor, the gear pump is connected with the motor;

[0011] High pressure oil circuit, which is connected with the discharge port of the gear pump;

[0012] Proportional valve, the oil inlet of which is connected with the high pressure oil circuit;

[0013] Pilot operated directional control valve, the oil inlet of which is connected with the high pressure oil circuit, and the oil return port of which is connected with low pressure oil return circuit;

[0014] Control oil circuit, which is arranged between the control oil port of the pilot operated directional control valve and the working oil port of the proportional valve, and is provided with a check valve, the oil inlet of which is connected with the working oil port of the proportional valve;

[0015] Switch valve, which is arranged between the high pressure oil circuit and the oil inlet of the pilot operated directional control valve, and is closed when the engine is not working, and is opened when the engine is working.

[0016] Preferably, it further comprises a flow valve, which is arranged between the control oil circuit and the low pressure oil return circuit.

[0017] Preferably, the proportional valve, the check valve, the pilot operated directional control valve and the switch valve are integrated in the same valve block.

[0018] Preferably, the working oil port of the proportional valve is connected with a load directional control valve, and the working oil port of the load directional control valve is connected with an actuator.

[0019] Preferably, the load reversing valve comprises a three-position five-way reversing valve or a two-position three-way reversing valve.

[0020] Preferably, the number of the proportional valves is at least two.

[0021] Preferably, the number of the load reversing valves connected to the working oil port of a single proportional valve is one or two.

[0022] Preferably, a safety overflow valve is further arranged between the high-pressure oil circuit and the low-pressure return oil circuit.

[0023] Preferably, the on-off valve is an electromagnetic valve.

[0024] The aerial work platform comprises a hybrid hydraulic system.

[0025] In the electric mode, the engine is separated from the motor, and the engine is in a non-working state. At this time, the motor works under the condition of battery power supply, and the motor drives the gear pump to rotate to supply hydraulic oil to the high-pressure oil circuit. In this working condition, the on-off valve is closed, so that the high-pressure oil circuit is not communicated with the hydraulic control reversing valve; at the same time, the opening of the proportional valve is in the maximum state, and the rotation speed of the motor is controlled to control the action speed of each actuator, that is, the maximum efficiency of the motor output is provided to the hydraulic system to drive the action of each actuator.

[0026] In the diesel mode, the engine is connected with the motor, and the motor is used as a generator. The engine works to drive the gear pump to rotate, and the remaining power of the engine is used to charge the battery of the motor (generator). In this working mode, the on-off valve is opened, so that the high-pressure oil circuit is communicated with the hydraulic control reversing valve, so that the hydraulic oil in the high-pressure oil circuit can flow to the hydraulic control reversing valve; at the same time, the opening size of the proportional valve is controlled by the current size of the proportional valve, so that the opening size of the proportional valve is controlled by controlling the current size of the proportional valve, that is, the flow of the proportional valve is controlled, so as to control the action speed of the actuator corresponding to the proportional valve; at this time, since the working oil port of the proportional valve is communicated with the control oil port of the hydraulic control reversing valve through the control oil circuit, under the action of the one-way valve, the hydraulic oil flowing out of the working oil port of the proportional valve is introduced into the control oil port of the hydraulic control reversing valve, so that one side of the hydraulic control reversing valve is the hydraulic oil of the high-pressure oil circuit, and the other side is the hydraulic oil of the working oil port of the proportional valve. At this time, the excess flow of the hydraulic oil of the high-pressure oil circuit minus the hydraulic oil of the proportional valve can be discharged to the low-pressure return oil circuit through the return port of the hydraulic control reversing valve. Under the condition of neglecting the pressure loss such as pipeline pressure loss, the pressure P of the discharge port of the gear pump is equal to the load pressure P fRoughly equal. Compared to existing technologies, it effectively reduces energy loss and increases the power output P of the engine's power generation section. m This makes the entire system more energy-efficient. Furthermore, since the pressure P at the outlet of the gear pump is approximately equal to the actual load pressure, the gears of the gear pump can be prevented from operating under high pressure for extended periods, thereby extending the service life of the gear pump.

[0027] The aerial work platform provided by this invention includes the aforementioned hybrid hydraulic system and has the same beneficial effects. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0029] Figure 1 The control principle diagram of the hybrid hydraulic system provided in a specific embodiment of the present invention is shown.

[0030] Figure 1 The accompanying figure labels are as follows:

[0031] 1 is the engine, 2 is the electric motor, 3 is the clutch, 4 is the gear pump, 5 is the high-pressure oil circuit, 6 is the proportional valve, 7 is the hydraulic directional valve, 8 is the control oil circuit, 9 is the low-pressure return oil circuit, 10 is the on / off valve, 11 is the check valve, 12 is the flow valve, 13 is the load directional valve, 14 is the safety relief valve, and 15 is the actuator functional valve group. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] The core of this invention is to provide a hybrid hydraulic system that reduces the outlet pressure of the gear pump in diesel mode without affecting the normal operation in electric mode. Therefore, it reduces energy loss, increases power generation efficiency, and extends the service life of the gear pump. Another core aspect of this invention is to provide an aerial work platform vehicle incorporating the aforementioned hybrid hydraulic system, which features low energy loss, high power generation efficiency, and a long service life for the gear pump.

[0034] Please refer to Figure 1The control principle diagram of the hybrid hydraulic system provided by the embodiment of the present application.

[0035] The present application provides a hybrid hydraulic system, which comprises an engine 1, an electric motor 2, a gear pump 4, a high-pressure oil circuit 5, a low-pressure return oil circuit 9, a control oil circuit 8, a proportional valve 6, a check valve 11, a hydraulic control reversing valve 7 and a switch valve 10.

[0036] Specifically, the engine 1 is connected with the electric motor 2, and the electric motor 2 is connected with the gear pump 4. It should be noted that the engine 1 and the electric motor 2 can be connected and disconnected to realize the switching between the electric mode and the diesel mode. Preferably, the engine 1 and the electric motor 2 are connected through a clutch 3. When the clutch 3 is coupled, the engine 1 and the electric motor 2 are connected; when the clutch 3 is disconnected, the engine 1 and the electric motor 2 are disconnected.

[0037] The high-pressure oil circuit 5 is connected with the discharge port of the gear pump 4, and the gear pump 4 provides hydraulic oil for the whole hybrid hydraulic system. The hydraulic oil provided by the gear pump 4 is delivered to each load circuit through the high-pressure oil circuit 5. The oil inlet of the proportional valve 6 and the oil inlet of the hydraulic control reversing valve 7 are connected with the high-pressure oil circuit 5, respectively. The low-pressure return oil circuit 9 is preferably connected with an oil tank for pressure relief and oil return. The control oil circuit 8 is arranged between the working oil port of the proportional valve 6 and the control oil port of the hydraulic control reversing valve 7. The control oil circuit 8 is provided with the check valve 11. The oil inlet of the check valve 11 is connected with the working oil port of the proportional valve 6, that is, the hydraulic oil can only flow from the working oil port of the proportional valve 6 to the hydraulic control reversing valve 7 through the control oil circuit 8, and cannot flow reversely. The oil return port of the hydraulic control reversing valve 7 is connected with the low-pressure return oil circuit 9. The switch valve 10 is arranged between the high-pressure oil circuit 5 and the oil inlet of the hydraulic control reversing valve 7, and is used for controlling the opening and closing of the oil circuit between the high-pressure oil circuit 5 and the hydraulic control reversing valve 7. When the engine 1 is not working, the switch valve 10 is closed; when the engine 1 is working, the switch valve 10 is opened.

[0038] It can be understood that when the hybrid hydraulic system is in the electric mode, the engine 1 is separated from the electric motor 2, and the engine 1 is in the non-working state. At this time, the electric motor 2 works under the condition of battery power supply, and the gear pump 4 is driven by the electric motor 2 to rotate to supply hydraulic oil to the high-pressure oil circuit 5. Under this working condition, the switch valve 10 is closed, so that the high-pressure oil circuit 5 and the hydraulic control reversing valve 7 are not connected; at the same time, the opening of the proportional valve 6 is in the maximum state. By controlling the rotating speed of the electric motor 2, the action speed of each actuator is controlled, that is, the maximum efficiency of the power output by the electric motor 2 is provided to the hydraulic system to drive the action of each actuator.

[0039] When the hybrid hydraulic system needs to be in the diesel mode, the engine 1 is connected with the motor 2, at this time, the motor 2 is used as a generator, works by the engine 1, drives the gear pump 4 to rotate through the motor 2, at the same time, the remaining power of the engine 1 is used to charge the battery of the motor 2 (generator). In this working mode, the switch valve 10 is opened, so that the high-pressure oil way 5 is communicated with the hydraulic control reversing valve 7, thus, the hydraulic oil of the high-pressure oil way 5 can flow to the hydraulic control reversing valve 7; at the same time, the opening size of the proportional valve 6 is controlled by the current size of the proportional valve 6, so as to control the opening size of the proportional valve 6 by controlling the current size of the proportional valve 6, that is, control the flow of the proportional valve 6, so as to control the action speed of the actuator corresponding to the proportional valve 6; at this time, since the working oil port of the proportional valve 6 is communicated with the control oil port of the hydraulic control reversing valve 7 through the control oil way 8, thus, under the action of the one-way valve 11, the hydraulic oil flowing out of the working oil port of the proportional valve 6 is introduced into the control oil port of the hydraulic control reversing valve 7, so that one side of the hydraulic control reversing valve 7 is the hydraulic oil of the high-pressure oil way 5, and the other side is the hydraulic oil of the working oil port of the proportional valve 6, at this time, the excess flow of the hydraulic oil of the high-pressure oil way 5 can be discharged to the low-pressure return oil way 9 through the return oil port of the hydraulic control reversing valve 7.

[0040] The person skilled in the art can understand that, in the diesel mode, the power P required to drive the gear pump 4 to rotate is proportional to the pressure P of the discharge port of the gear pump 4 and the flow Q of the discharge port of the gear pump 4. P That is:

[0041]

[0042] Wherein, Q is the flow of the discharge port of the gear pump 4, P is the pressure of the discharge port of the gear pump 4, and η is the efficiency of the gear pump 4. Since the engine 1 rotates at a constant speed in the diesel mode, that is, the speed n of the engine 1 is constant, and the displacement V of the gear pump 4 is constant, thus, the flow Q of the discharge port of the gear pump 4 is constant, wherein Q=n*V. At the same time, η is constant. Therefore, the power P required to drive the gear pump 4 to rotate is proportional to the pressure P of the discharge port of the gear pump 4 and the flow Q of the discharge port of the gear pump 4. P .

[0043] From the above content, it can be seen that, in the diesel mode, the switch valve 10 is opened, so that the hydraulic control reversing valve 7 is communicated with the high-pressure oil way 5, at the same time, the hydraulic oil of the working oil port of the proportional valve 6 flows into the control oil port of the hydraulic control reversing valve 7 through the control oil way 8 under the action of the one-way valve 11, that is, the actual load pressure is fed back to the hydraulic control reversing valve 7 through the control oil way 8, thus, the excess flow of the gear pump 4 except the load required flow can be discharged to the low-pressure return oil way 9 through the hydraulic control reversing valve 7. It can be seen that, in the case of ignoring the pressure loss such as pipeline pressure loss, the pressure P of the discharge port of the gear pump 4 is approximately equal to the load pressure P f , that is, P≈Pf Therefore, the power P required to drive the gear pump 4 to rotate can be approximately considered as P :

[0044]

[0045] Compared with the prior art, in the diesel mode, the pressure relief is not performed by the hydraulic control reversing valve 7, but by the overflow valve, that is, the gear pump 4 discharges the hydraulic oil at the maximum required flow of the load, so that the flow discharged from the discharge port of the gear pump 4 is greater than the actual flow required by some actuators, which causes the excess flow to form a pressure build-up at the discharge port of the gear pump 4, and when the pressure rises to the set value of the overflow valve, the overflow valve is opened to discharge the excess flow to the low-pressure return oil circuit 9. Therefore, it can be known that the pressure P at the discharge port of the gear pump 4 is much greater than the pressure P required by the actual load f , so that the energy loss is large.

[0046] It can be seen that the hybrid hydraulic system provided by the present application effectively reduces the energy loss.

[0047] In addition, since in the diesel mode, the excess power of the engine 1 is used to charge the motor 2 (used as a generator), the power provided by the engine 1 for the part of generating electricity for the motor 2 (generator) is referred to as P m in the present application. m =(P W -P P )*η w . Wherein P W is the total power output by the engine 1, P P is the power required to drive the gear pump 4 to rotate in the power output by the engine 1 as described above, and η w is the transmission efficiency. As described above, the hybrid hydraulic system provided by the present application effectively reduces the power P required to drive the gear pump 4 to rotate P , so that the power P used for generating electricity by the engine 1 is correspondingly increased m , so that the entire system is more energy-saving.

[0048] Further, since the pressure P at the discharge port of the gear pump 4 is approximately equal to the actual load pressure, the gears of the gear pump 4 can be prevented from working in a high-pressure state for a long time, so that the service life of the gear pump 4 can be improved. Moreover, it is known that when the overflow valve is opened in a high-pressure overflow state, the oil temperature of the hydraulic system will rapidly rise, and therefore, the hybrid hydraulic system provided by the present application also effectively avoids the oil temperature rise phenomenon caused by the long-time opening of the overflow valve, and avoids the adverse effects of the hydraulic oil temperature rise on the hydraulic system.

[0049] In addition, in order to make the control oil circuit 8 return to the initial state after each time the actuator stops, avoid the pressure in the control oil circuit 8, and affect the next load operation, on the basis of the above embodiment, a flow valve 12 is arranged between the control oil circuit 8 and the low-pressure return oil circuit 9. That is, when the actuator stops, the pressure in the control oil circuit 8 can be discharged from the flow valve 12 to the low-pressure return oil circuit 9, so that the control oil circuit 8 returns to the initial state, thereby ensuring the normal operation of the hydraulic control reversing valve 7.

[0050] In consideration of the convenience of installation, on the basis of the above embodiment, the proportional valve 6, the check valve 11, the hydraulic control reversing valve 7, and the on-off valve 10 are integrated into the same valve block to form an actuator function valve group 15.

[0051] That is, the proportional valve 6, the check valve 11, the hydraulic control reversing valve 7, and the on-off valve 10 are integrated into one whole valve group in the embodiment, which facilitates one-time installation. At the same time, through the joint use of the on-off valve 10, the hydraulic control reversing valve 7, and the control oil circuit 8 for load feedback, the versatility of the electric mode and the diesel mode in the same valve group can be realized.

[0052] It should be noted that when the hybrid hydraulic system further includes the flow valve 12, the flow valve 12, the proportional valve 6, the check valve 11, the hydraulic control reversing valve 7, and the on-off valve 10 can also be integrated into one whole valve group.

[0053] In order to control the direction of the actuator, on the basis of the above embodiment, as shown in FIG. 6, a load reversing valve 13 is connected to the working oil port of the proportional valve 6, and the control oil port of the load reversing valve 13 is connected to the actuator. Figure 1

[0054] That is, in the embodiment, the hydraulic oil flowing out of the proportional valve 6 enters the load reversing valve 13, and the direction of the actuator is controlled by switching the load reversing valve 13, so as to flexibly adjust the operation of the load.

[0055] It should be noted that the specific type of the load reversing valve 13 is not limited in the embodiment, and preferably, on the basis of the above embodiment, the load reversing valve 13 includes a three-position five-way reversing valve or a two-position three-way reversing valve.

[0056] In addition, in each of the above embodiments, the specific number of the proportional valve 6 is not limited, and preferably, on the basis of the above embodiment, the number of the proportional valve 6 is at least two. For example, the number of the proportional valve 6 can be preferably four.

[0057] It can be understood that the more the number of the proportional valve 6 is, the more the corresponding actuators are, and the independent movement of multiple actuators can be realized.

[0058] ​Furthermore, based on the above embodiments, the number of load directional valves 13 connected to the working port of a single proportional valve 6 is one or two.

[0059] In other words, in this embodiment, the switching of an actuator can be achieved by one load switching valve 13 or by two load switching valves 13.

[0060] like Figure 1 As shown, the working port of a proportional valve 6 can be connected to a three-position five-way directional valve, and the working port of a proportional valve 6 can also be connected to two two-position three-way directional valves.

[0061] Furthermore, considering safety, in addition to the above embodiments, a safety relief valve 14 is also provided between the high-pressure oil circuit 5 and the low-pressure return oil circuit 9.

[0062] That is, when the pressure at the outlet of gear pump 4 rises to the set value of safety relief valve 14, safety relief valve 14 opens to relieve pressure and ensure the safety of the hybrid hydraulic system.

[0063] It should be noted that the specific type of the switching valve 10 is not limited in the above embodiments. Preferably, the switching valve 10 is a solenoid valve, that is, the solenoid valve is opened or closed by controlling whether the solenoid valve is energized. That is, in electric mode, the solenoid valve is not energized; in diesel mode, the solenoid valve is energized and opened.

[0064] Furthermore, the load reversing valve 13 and the safety relief valve 14 can also be integrated into the same valve block formed by the proportional valve 6, the hydraulic reversing valve 7, the on / off valve 10, and the flow valve 12.

[0065] In addition to the hybrid hydraulic system described above, the present invention also provides an aerial work platform vehicle that includes the hybrid hydraulic system disclosed in the above embodiments. The structure of other parts of the aerial work platform vehicle is described in the prior art and will not be repeated here.

[0066] The aerial work platform is characterized by employing a hybrid hydraulic system disclosed in any of the above embodiments, in order to reduce energy loss, increase power generation efficiency, and extend the service life of the gear pump 4.

[0067] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0068] The above describes the hybrid hydraulic system and aerial work vehicle provided by the application in detail. The principles and implementation manners of the application are described by using specific examples, and the above description of the examples is only used to help understand the method of the application and the core idea thereof. It should be noted that, for those skilled in the art, some improvements and modifications can be made to the application without departing from the principles of the application, and these improvements and modifications also fall within the protection scope of the claims of the application.

Claims

1. A hybrid hydraulic system, characterized by, It comprises: an engine (1), an electric motor (2) and a gear pump (4), the engine (1) being separable and connectable with the electric motor (2), the gear pump (4) being connected with the electric motor (2); a high-pressure oil circuit (5) connected with the discharge port of the gear pump (4); a proportional valve (6) with an oil inlet connected with the high-pressure oil circuit (5); a hydraulic control reversing valve (7) with an oil inlet connected with the high-pressure oil circuit (5) and an oil return port connected with a low-pressure oil return circuit (9); a control oil circuit (8) provided between the control oil port of the hydraulic control reversing valve (7) and the working oil port of the proportional valve (6), the control oil circuit (8) being provided with a check valve (11) with an oil inlet connected with the working oil port of the proportional valve (6); a switch valve (10) provided between the high-pressure oil circuit (5) and the oil inlet of the hydraulic control reversing valve (7), the switch valve (10) being closed when the engine (1) is not working and being opened when the engine (1) is working; when the hybrid hydraulic system is in the electric mode, the engine (1) is in the non-working state, the switch valve (10) is closed, the high-pressure oil circuit (5) is not connected with the hydraulic control reversing valve (7), the opening of the proportional valve (6) is in the maximum state, and the speed of the action of each actuator is controlled by controlling the rotating speed of the electric motor (2); when the hybrid hydraulic system is in the diesel mode, the engine (1) is working, the switch valve (10) is opened, the high-pressure oil circuit (5) is connected with the hydraulic control reversing valve (7), the opening size of the proportional valve (6) is controlled by controlling the current size of the proportional valve (6), the hydraulic oil flowing out of the working oil port of the proportional valve (6) is introduced into the control oil port of the hydraulic control reversing valve (7) under the action of the check valve (11), one side of the hydraulic control reversing valve (7) is the hydraulic oil of the high-pressure oil circuit (5), the other side is the working oil port hydraulic oil of the proportional valve (6), and the excess flow of the hydraulic oil of the high-pressure oil circuit (5) is discharged to the low-pressure oil return circuit (9) through the oil return port of the hydraulic control reversing valve (7).

2. The hybrid hydraulic system of claim 1, wherein, It further comprises a flow valve (12) provided between the control oil circuit (8) and the low-pressure oil return circuit (9).

3. The hybrid hydraulic system of claim 1 or 2, wherein, The proportional valve (6), the check valve (11), the hydraulic control reversing valve (7) and the switch valve (10) are integrated in the same valve block.

4. The hybrid hydraulic system of claim 3, wherein, The control oil port of the proportional valve (6) is connected with a load reversing valve (13), and the control oil port of the load reversing valve (13) is connected with an actuator.

5. The hybrid hydraulic system of claim 4, wherein, The load reversing valve (13) comprises a three-position five-way reversing valve or a two-position three-way reversing valve.

6. The hybrid hydraulic system of claim 4, wherein, The number of the proportional valves (6) is at least two.

7. The hybrid hydraulic system of claim 6, wherein, The number of the load reversing valves (13) connected with the working oil port of a single proportional valve (6) is one or two.

8. The hybrid hydraulic system of claim 3, wherein, A safety overflow valve (14) is further included between the high-pressure oil passage (5) and the low-pressure oil return passage (9).

9. The hybrid hydraulic system of claim 3, wherein, The on-off valve (10) is an electromagnetic valve.

10. An aerial device comprising a hybrid hydraulic system, characterized in that, The hybrid hydraulic system is the hybrid hydraulic system according to any one of claims 1-9.

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