Hydraulic system, energy recovery method and engineering machinery

Abstract

The invention discloses a hydraulic system, an energy recovery method and engineering machinery. The hydraulic system comprises a front pump, a rear pump and a hydraulic system, wherein the front pump is used for driving a working device I; the rear pump is used for driving the working device II; the front pump and the rear pump are coaxially connected and are in transmission connection with the output end of the motor; the second working device comprises a third reversing valve, an inlet of the third reversing valve is connected with an outlet of the rear pump, and a working oil port of the third reversing valve is connected with a large cavity and a small cavity of a third oil cylinder. When the third oil cylinder retracts under the action of gravity, the rear pump is switched to be in the motor working condition, hydraulic oil in a large cavity of the third oil cylinder enters the rear pump in the motor working condition through the third reversing valve, and the rear pump in the motor working condition is used for driving the front pump and / or the motor. The system has the characteristics of simple structure, short energy recovery path, high energy recovery efficiency, good stability and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of engineering machinery, and in particular relates to a hydraulic system, an energy recovery method and engineering machinery. Background Art

[0002] In the hydraulic system of existing engineering machinery (such as excavators, transfer machines and cranes, etc.), when the cylinder retracts, the high-pressure oil in the rodless chamber of the cylinder can only be lost through the overflow of the safety valve, which not only causes the entire hydraulic system to overheat easily in a high temperature environment, but also increases the fuel consumption of the main machine. The existing hydraulic systems with energy recovery function generally have problems such as complex system structure, long energy recovery path, low energy recovery efficiency and poor stability. Summary of the invention

[0003] In order to solve the deficiencies in the prior art, the present invention provides a hydraulic system, an energy recovery method and engineering machinery, which have the characteristics of simple system structure, short energy recovery path, high energy recovery efficiency and good stability.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is: In a first aspect, a hydraulic system is provided, comprising: a front pump for driving a working device one; a rear pump for driving a working device two; the front pump is coaxially connected to the rear pump and is transmission-connected to the output end of the motor; the working device two comprises a reversing valve three, the inlet of the reversing valve three is connected to the outlet of the rear pump, and the working oil port of the reversing valve three is respectively connected to the large chamber and the small chamber of the oil cylinder three; when the oil cylinder three retracts under the action of gravity, the rear pump switches to a motor operating state, and the hydraulic oil in the three large chambers of the oil cylinder enters the rear pump in the motor operating state through the reversing valve three, and the rear pump in the motor operating state is used to drive the front pump and / or the motor.

[0005] Further, when the output torque of the rear pump in the motor working state is less than the input torque required by the front pump, the rear pump in the motor working state drives the front pump to work together with the motor.

[0006] Furthermore, when the output torque of the rear pump in the motor working state is greater than the input torque required by the front pump, the output torque of the rear pump in the motor working state is used to drive the motor to generate electricity in addition to driving the front pump.

[0007] Furthermore, the rear pump is a two-quadrant plunger pump, and the rear pump is switched to a motor operating mode, specifically: the variable mechanism of the plunger pump drives the swash plate to move, so that the swash plate swing angle changes from a positive direction to a negative direction.

[0008] Furthermore, a safety valve is provided on the hydraulic pipeline between the outlet of the rear pump and the inlet of the reversing valve three.

[0009] Furthermore, the working device 1 includes a reversing valve 1 and a reversing valve 2, the inlets of the reversing valve 1 and the reversing valve 2 are respectively connected to the outlet of the front pump, the working oil port of the reversing valve 1 is respectively connected to the large chamber and the small chamber of the oil cylinder 1, and the working oil port of the reversing valve 2 is respectively connected to the large chamber and the small chamber of the oil cylinder 2.

[0010] Furthermore, it also includes a reversing valve four, the inlet of the reversing valve four is connected to the large chamber of the oil cylinder three, and the outlet of the reversing valve four is connected to the inlet of the working device one.

[0011] In a second aspect, a method for energy recovery of a hydraulic system is provided, wherein the hydraulic system is the hydraulic system described in the first aspect; the method comprises: obtaining operating condition information of cylinder three; in response to the operating condition information of cylinder three being that cylinder three is retracted under the action of gravity, switching the rear pump to a motor operating condition, and at the same time, reversing the reversing valve three to introduce the hydraulic oil in the three large chambers of the cylinder into the rear pump in the motor operating condition through the reversing valve three, for driving the front pump and / or the motor.

[0012] According to a third aspect, there is provided an engineering machine, wherein the engineering machine is equipped with the hydraulic system according to the first aspect.

[0013] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: the present invention is provided by a front pump for driving the working device one; a rear pump for driving the working device two; the front pump is coaxially connected with the rear pump and is transmission-connected with the output end of the motor; the working device two includes a reversing valve three, the inlet of the reversing valve three is connected with the outlet of the rear pump, and the working oil port of the reversing valve three is respectively connected to the large chamber and the small chamber of the oil cylinder three; when the oil cylinder three retracts under the action of gravity, the rear pump switches to the motor working condition, and the hydraulic oil in the three large chambers of the oil cylinder enters the rear pump in the motor working condition through the reversing valve three, and the rear pump in the motor working condition is used to drive the front pump and / or the motor to realize energy recovery, and has the characteristics of simple system structure, short energy recovery path, high energy recovery efficiency, good stability, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 The schematic diagram of a hydraulic system provided by an embodiment of the present invention is Figure 1 ; Figure 2 The schematic diagram of a hydraulic system provided by an embodiment of the present invention is Figure 2 ; In the figure: 1. Motor; 2. Front pump; 3. Rear pump; 4. Reversing valve one; 5. Reversing valve two; 6. Cylinder one; 7. Cylinder two; 8. Cylinder three; 9. Reversing valve three; 10. Safety valve; 11. Reversing valve four. DETAILED DESCRIPTION

[0015] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0016] Embodiment 1 like Figure 1 As shown, a hydraulic system with energy recovery function includes: a front pump 2 for driving a working device 1, and a rear pump 3 for driving a working device 2, wherein the front pump 2 is coaxially connected with the rear pump 3 and is transmission-connected to the output end of the motor 1. The rear pump 3 is a two-quadrant plunger pump, and has two working modes: pump working mode and motor working mode.

[0017] The working device 1 includes a reversing valve 1 4 and a reversing valve 2 5. The inlets of the reversing valve 1 4 and the reversing valve 2 5 are respectively connected to the outlet of the front pump 2. The working oil port of the reversing valve 1 4 is respectively connected to the large chamber and the small chamber of the oil cylinder 1 6. The working oil port of the reversing valve 2 5 is respectively connected to the large chamber and the small chamber of the oil cylinder 2 7.

[0018] The working device 2 includes a reversing valve 3 9, the inlet of the reversing valve 3 9 is connected to the outlet of the rear pump 3, and the working oil port of the reversing valve 3 9 is respectively connected to the large chamber and the small chamber of the oil cylinder 3 8. A safety valve 10 is arranged on the hydraulic pipeline between the outlet of the rear pump 3 and the inlet of the reversing valve 3 9.

[0019] When the oil cylinder three 8 retracts under the action of gravity, the rear pump 3 switches to the motor working state, and the hydraulic oil in the large chamber of the oil cylinder three 8 enters the rear pump 3 in the motor working state through the reversing valve three 9. The rear pump 3 in the motor working state is used to drive the front pump 2 and / or the motor 1, thereby realizing energy recovery and utilization.

[0020] When the system does not start the energy recovery function, the rear pump 3 is in the pump working state; the extension or retraction of the oil cylinder 3 8 is realized by the reversing valve 3 9. When the energy recovery function of the oil cylinder 3 8 needs to be turned on, if the working state of the oil cylinder 3 8 is: retracted under the action of gravity; at this time, the variable mechanism of the rear pump 3 pushes the swash plate to move, so that the swash plate swing angle changes from positive to negative, and at this time, the rear pump 3 switches to the motor working state.

[0021] If the output torque of the rear pump 3 is less than the input torque required by the front pump 2, the rear pump 3 in the motor working state and the motor 1 drive the front pump 2 to work together, and the energy recovery path is (hydraulic potential energy in the large cavity of the oil cylinder 3 8) → (mechanical energy of the front pump 2), and the excess hydraulic potential energy is directly converted into mechanical energy to drive the front pump 2 to work; when the output torque of the rear pump 3 is greater than the input torque required for the front pump 2 to work, the output torque of the rear pump 3 in the motor working state is used to drive the front pump 2 to work, and the remaining part will drag the motor 1, so that the motor 1 switches to the generator working state, and the excess mechanical energy is stored in the form of electrical energy. At this time, part of the hydraulic potential energy when the oil cylinder 3 8 is retracted drives the front pump to work through hydraulic potential energy → mechanical energy, and the remaining part is converted and stored through the conversion path of hydraulic potential energy → mechanical energy → electrical energy. When the front pump 2 is not working or is in an unloaded working state, the hydraulic potential energy of the retracted oil cylinder 3 8 is converted and stored through the conversion path of hydraulic potential energy → mechanical energy → electrical energy.

[0022] When the oil cylinder retracts, the present invention controls the swash plate angle of the rear pump to change from a positive swing angle to a negative swing angle, and then controls the reversing of the reversing valve three, so that the hydraulic potential energy of the oil cylinder three when it retracts under the action of gravity enters the oil outlet of the rear pump through the reversing valve three. At this time, the rear pump switches to the motor working state. If the output torque of the rear pump is less than the input torque required by the front pump, the rear pump drives the front pump to work together with the motor in the motor working state; when the output torque of the rear pump is greater than the input torque required when the front pump works, the rear pump drives the front pump to work and drags the motor to generate electricity; the hydraulic potential energy can be effectively recycled.

[0023] The two energy recovery paths are customized by the mechanical characteristics of the designed hydraulic system. The first priority is to drive the front pump, and then the excess hydraulic energy is converted into electrical energy for storage. This process can automatically realize the selection of two energy recovery paths only through the mechanical structure itself (no additional electronic control system and hydraulic components are required). It has the characteristics of simple energy recovery path, high energy recovery efficiency, high reliability of hydraulic system and low cost.

[0024] Compared with the closed hydraulic system circuit, the present invention does not require an additional oil replenishment circuit to replenish oil to the system, and maintains the inherent advantage of good heat dissipation of the open system. The hydraulic system of the present invention only needs a high-power motor to drive two main pumps to work at the same time, which reduces the number of hydraulic system components and makes the pipeline connection simpler and more time-saving.

[0025] Embodiment 2 Based on the hydraulic system with energy recovery function described in the first embodiment, this embodiment adds a two-position two-way electromagnetic reversing valve (reversing valve 411, such as Figure 2As shown in the figure, the high-pressure oil in the large cavity is regenerated into the cavity of cylinder 1 6 or cylinder 2 7 when cylinder 8 is retracted, thereby realizing the third energy recovery path. The energy transfer route of this path is the hydraulic potential energy when cylinder 3 8 is retracted under the action of gravity → mechanical energy to drive cylinder 1 6 or cylinder 2 7 to move.

[0026] Embodiment 3 Based on the hydraulic system with energy recovery function described in Embodiment 1 and Embodiment 2, this embodiment provides an energy recovery method for a hydraulic system, including: Get the working condition information of cylinder 3 8; In response to the operating condition information of cylinder three 8 that cylinder three 8 retracts under the action of gravity, the rear pump 3 is switched to the motor operating condition. At the same time, the reversing valve three 9 is reversed to introduce the hydraulic oil in the large chamber of cylinder three 8 into the rear pump 3 in the motor operating condition through the reversing valve three 9, so as to drive the front pump 2 and / or the motor 1.

[0027] When the output torque of the rear pump 3 in the motor working state is less than the input torque required by the front pump 2 , the rear pump 3 in the motor working state drives the front pump 2 to work together with the motor 1 .

[0028] When the output torque of the rear pump 3 in the motor working state is greater than the input torque required by the front pump 2, the output torque of the rear pump 3 in the motor working state is used to drive the motor 1 to generate electricity in addition to driving the front pump 2 to work.

[0029] Embodiment 4 Based on the hydraulic system with energy recovery function described in the first and second embodiments, this embodiment provides a construction machinery, wherein the construction machinery is equipped with the hydraulic system with energy recovery function described in the first or second embodiment.

[0030] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A hydraulic system, characterized in that: include: A front pump (2) for driving a working device 1; A rear pump (3) for driving a second working device; The front pump (2) is coaxially connected to the rear pump (3) and is drivingly connected to the output end of the motor (1); The working device 2 comprises a reversing valve 3 (9), the inlet of the reversing valve 3 (9) is connected to the outlet of the rear pump (3), and the working oil port of the reversing valve 3 (9) is respectively connected to the large chamber and the small chamber of the oil cylinder 3 (8); When the oil cylinder three (8) retracts under the action of gravity, the rear pump (3) switches to a motor operating state, and the hydraulic oil in the large chamber of the oil cylinder three (8) enters the rear pump (3) in a motor operating state through the reversing valve three (9). The rear pump (3) in a motor operating state is used to drive the front pump (2) and / or the motor (1).

2. The hydraulic system according to claim 1, characterized in that: When the output torque of the rear pump (3) in the motor working state is less than the input torque required by the front pump (2), the rear pump (3) in the motor working state drives the front pump (2) together with the motor (1) to work.

3. The hydraulic system according to claim 1, characterized in that: When the output torque of the rear pump (3) in the motor working state is greater than the input torque required by the front pump (2), the output torque of the rear pump (3) in the motor working state is used to drive the motor (1) to generate electricity in addition to driving the front pump (2) to work.

4. The hydraulic system according to claim 1, characterized in that: The rear pump (3) is a two-quadrant plunger pump. The rear pump (3) is switched to a motor operating mode, specifically: the variable mechanism of the plunger pump drives the swash plate to move, so that the swash plate swing angle changes from a positive direction to a negative direction.

5. The hydraulic system according to claim 1, characterized in that: A safety valve (10) is provided on the hydraulic pipeline between the outlet of the rear pump (3) and the inlet of the third reversing valve (9).

6. The hydraulic system according to claim 1, characterized in that: The working device 1 comprises a reversing valve 1 (4) and a reversing valve 2 (5). The inlets of the reversing valve 1 (4) and the reversing valve 2 (5) are respectively connected to the outlet of the front pump (2). The working oil port of the reversing valve 1 (4) is respectively connected to the large chamber and the small chamber of the oil cylinder 1 (6). The working oil port of the reversing valve 2 (5) is respectively connected to the large chamber and the small chamber of the oil cylinder 2 (7).

7. The hydraulic system according to claim 1, characterized in that: It also includes a reversing valve four (11), the inlet of the reversing valve four (11) is connected to the large chamber of the oil cylinder three (8), and the outlet of the reversing valve four (11) is connected to the inlet of the working device one.

8. A method for energy recovery of a hydraulic system, characterized in that: The hydraulic system is the hydraulic system according to any one of claims 1 to 7; the method comprises: Obtain the working condition information of cylinder three (8); In response to the operating condition information of the oil cylinder three (8) that the oil cylinder three (8) is retracted under the action of gravity, the rear pump (3) is switched to the motor operating condition. At the same time, the reversing valve three (9) is switched to guide the hydraulic oil in the large chamber of the oil cylinder three (8) through the reversing valve three (9) into the rear pump (3) in the motor operating condition, so as to drive the front pump (2) and / or the motor (1).

9. The energy recovery method of a hydraulic system according to claim 8, characterized in that: When the output torque of the rear pump (3) in the motor working state is less than the input torque required by the front pump (2), the rear pump (3) in the motor working state drives the front pump (2) together with the motor (1) to work; When the output torque of the rear pump (3) in the motor working state is greater than the input torque required by the front pump (2), the output torque of the rear pump (3) in the motor working state is used to drive the motor (1) to generate electricity in addition to driving the front pump (2) to work.

10. An engineering machine, characterized in that: The engineering machinery is equipped with the hydraulic system according to any one of claims 1 to 7.

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