Pump-control direct-drive distributed hydraulic system of excavator and control method

Abstract

The invention discloses an excavator pump control direct drive distributed hydraulic system and a control method. A first oil port of a variable hydraulic pump is connected with an oil inlet of a first hydraulic control one-way valve through an oil way, and an oil outlet of the first hydraulic control one-way valve is connected with a rodless cavity through an oil way; the rod cavity is connected with an oil inlet of a second hydraulic control one-way valve through an oil way, and an oil outlet of the second hydraulic control one-way valve is connected with a second oil port of the volume adjustable hydraulic pump through an oil way. A rodless cavity of the hydraulic cylinder is sequentially communicated with an oil inlet of the first one-way valve, an oil outlet of the first one-way valve is sequentially communicated with an oil outlet of the second one-way valve, and an oil inlet of the second one-way valve is sequentially communicated with a rod cavity of the hydraulic cylinder; an oil outlet of the first one-way valve and an oil outlet of the second one-way valve are communicated with a control oil port of the first hydraulic control one-way valve and a control oil port of the second hydraulic control one-way valve through the first reversing valve; the throttling loss of the hydraulic system can be eliminated.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydraulic control of excavators, and in particular relates to a pump-controlled direct-drive distributed hydraulic system and a control method for an excavator. Background Art

[0002] Excavators play an important role in engineering construction and maintain a growth trend. The electrification of excavators continues to accelerate. At present, the configuration commonly used by electric excavators is oil-to-electric mode, that is, the electric motor replaces the engine as the power source. Its hydraulic system still uses a centralized valve-controlled hydraulic system, using a single fixed-displacement pump to provide power to the hydraulic system through a multi-way valve. When performing compound actions, in order to meet the power requirements of different actuators, it is necessary to throttle and control the system pressure through a multi-way valve, resulting in energy loss in the system, resulting in low efficiency and serious heat generation of the entire system.

[0003] With the development of servo motor control technology, the use of hydraulic pumps to directly control actuators has become the direction and development trend for improving the efficiency of hydraulic systems. The pump-controlled direct drive method eliminates the need for a control valve, reduces the throttling loss of the hydraulic system, and avoids control valve failure problems.

[0004] However, the existing technology has not been able to fully realize pump-controlled direct drive (for example, a distributed direct-drive excavator hydraulic system with a servo motor driving a dual variable pump, application number CN201810342465.3), and there is still a small amount of throttling loss in the hydraulic valve; in addition, there are some existing systems (for example, a distributed direct-drive excavator hydraulic system with a motor driving a dual fixed-displacement pump and a dual accumulator, application number CN201810709211.0) in which one actuator is driven by two variable pumps, and the system cost is higher. Summary of the invention

[0005] The purpose of the present invention is to provide an excavator pump-controlled direct-drive distributed hydraulic system and control method, which can eliminate the throttling loss of the hydraulic system and at the same time recover the gravitational potential energy of the excavator to improve the endurance.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: In a first aspect, the present invention provides a pump-controlled direct-drive distributed hydraulic system for an excavator, comprising a hydraulic cylinder for driving a boom, a bucket or a dipper arm and a cylinder drive unit; The oil cylinder drive unit comprises a servo motor and a variable hydraulic pump which are connected in a transmission manner, the servo motor is electrically connected to the energy storage battery, the first oil port of the variable hydraulic pump is connected to the oil inlet of the first hydraulically controlled one-way valve through an oil circuit, the oil outlet of the first hydraulically controlled one-way valve is connected to the rodless chamber of the hydraulic cylinder through an oil circuit; the rod chamber of the hydraulic cylinder is connected to the oil inlet of the second hydraulically controlled one-way valve through an oil circuit, and the oil outlet of the second hydraulically controlled one-way valve is connected to the second oil port of the variable hydraulic pump through an oil circuit; The rodless chamber of the hydraulic cylinder is connected in sequence to the oil inlet of the first one-way valve, the oil outlet of the first one-way valve is connected to the oil outlet of the second one-way valve, and the oil inlet of the second one-way valve is connected to the rod chamber of the hydraulic cylinder; The oil outlet of the first one-way valve and the oil outlet of the second one-way valve are connected to the control oil port of the first hydraulically controlled one-way valve and the control oil port of the second hydraulically controlled one-way valve through the first reversing valve.

[0007] Furthermore, it also includes a third control one-way valve, a fourth control one-way valve and an accumulator; the oil inlet of the third control one-way valve and the oil inlet of the fourth control one-way valve are connected to the accumulator; the first oil port of the variable hydraulic pump is connected to the oil outlet of the third control one-way valve through an oil circuit, and the first oil port of the variable hydraulic pump is connected to the control oil port of the fourth control one-way valve through an oil circuit; the second oil port of the variable hydraulic pump is connected to the oil outlet of the fourth control one-way valve through an oil circuit, and the second oil port of the variable hydraulic pump is connected to the control oil port of the third control one-way valve through an oil circuit.

[0008] Furthermore, the oil outlet of the first hydraulically controlled one-way valve is connected to the oil inlet of the third control one-way valve and the oil inlet of the fourth control one-way valve through the first overflow valve.

[0009] Furthermore, the oil inlet of the second hydraulically controlled one-way valve is connected to the oil inlet of the third control one-way valve and the oil inlet of the fourth control one-way valve through the second overflow valve.

[0010] Furthermore, the oil outlet of the first overflow valve and the oil outlet of the second overflow valve are connected to the control oil port of the first hydraulically controlled one-way valve and the control oil port of the second hydraulically controlled one-way valve through the first reversing valve.

[0011] Furthermore, the first reversing valve is set as a two-position three-way solenoid valve. When the first reversing valve is in the first working position, the oil outlet of the first one-way valve and the oil outlet of the second one-way valve are connected to the control oil port of the first hydraulically controlled one-way valve and the control oil port of the second hydraulically controlled one-way valve; when the first reversing valve is in the second working position, the oil outlet of the first overflow valve and the oil outlet of the second overflow valve are connected to the control oil port of the first hydraulically controlled one-way valve and the control oil port of the second hydraulically controlled one-way valve.

[0012] Furthermore, it also includes a travel drive unit, which is equipped with a high-speed motor, a quantitative hydraulic pump and a travel hydraulic motor; the high-speed motor drives the quantitative hydraulic pump to move; the quantitative hydraulic pump drives the travel hydraulic motor to move, and the travel hydraulic motor drives the travel mechanism of the excavator to move.

[0013] Furthermore, the oil outlet of the quantitative hydraulic pump is connected to the oil inlet of the travel hydraulic motor, and the oil outlet of the travel hydraulic motor is connected to the oil inlet of the quantitative hydraulic pump; the oil inlet of the travel hydraulic motor and the oil outlet of the travel hydraulic motor are connected to the oil tank through a second reversing valve; the second reversing valve is set as a three-position three-way solenoid valve, and when the second reversing valve is in the first position, the oil inlet of the travel hydraulic motor is connected to the oil tank; when the second reversing valve is in the second position, the oil inlet of the travel hydraulic motor and the oil tank, and the oil inlet of the travel hydraulic motor and the oil tank are both disconnected; when the second reversing valve is in the third position, the oil outlet of the travel hydraulic motor is connected to the oil tank.

[0014] Furthermore, a third overflow valve and a cooler are provided on the oil circuit between the second reversing valve and the oil tank.

[0015] Furthermore, the travel drive unit also includes a fourth overflow valve and a fifth overflow valve; the oil outlet of the quantitative hydraulic pump is connected to the oil inlet of the fourth overflow valve, and the oil outlet of the fourth overflow valve is connected to the oil inlet of the quantitative hydraulic pump in sequence; the oil inlet of the quantitative hydraulic pump is connected to the oil inlet of the fifth overflow valve, and the oil outlet of the fifth overflow valve is connected to the oil outlet of the quantitative hydraulic pump in sequence.

[0016] Furthermore, the travel drive unit also includes an oil replenishment pump, the oil inlet of the oil replenishment pump is connected to the oil tank; the oil outlet of the oil replenishment pump is connected to the oil inlet of the third one-way valve and the oil inlet of the fourth one-way valve through an oil circuit; the oil outlet of the third one-way valve is connected to the oil inlet of the travel hydraulic motor, and the oil outlet of the fourth one-way valve is connected to the oil inlet of the quantitative hydraulic pump.

[0017] In a second aspect, the present invention provides a control method for an excavator pump-controlled direct-drive distributed hydraulic system, comprising: When the hydraulic cylinder is in an extended state and the load direction is the same as the movement direction of the hydraulic cylinder, the oil outlet of the first check valve and the oil outlet of the second check valve are controlled by the first reversing valve to connect the control oil outlet of the first hydraulically controlled check valve and the control oil outlet of the second hydraulically controlled check valve, and the high-pressure hydraulic oil in the rod chamber of the hydraulic cylinder enters the control oil outlet of the second hydraulically controlled check valve. The second hydraulically controlled check valve is opened in reverse, and the high-pressure hydraulic oil in the rod chamber of the hydraulic cylinder flows to the variable hydraulic pump. The high-pressure hydraulic oil drives the variable hydraulic pump to move forward to drive the hydraulic oil to flow. The hydraulic oil enters the rodless chamber of the hydraulic cylinder from the first oil outlet of the variable hydraulic pump through the first hydraulically controlled check valve; the variable hydraulic pump drives the servo motor to rotate to generate electricity and stores it in the energy storage battery; When the hydraulic cylinder is in an extended state and the load direction is opposite to the movement direction of the hydraulic cylinder, the servo motor is controlled to drive the variable hydraulic pump to move forward to drive the hydraulic oil to flow, and the hydraulic oil enters the rodless chamber of the hydraulic cylinder from the first oil port of the variable hydraulic pump through the first hydraulically controlled one-way valve; the oil outlet of the first one-way valve is controlled by the first reversing valve to connect the control oil port of the first hydraulically controlled one-way valve and the control oil port of the second hydraulically controlled one-way valve, and the high-pressure hydraulic oil in the rodless chamber of the hydraulic cylinder enters the control oil port of the second hydraulically controlled one-way valve, and the second hydraulically controlled one-way valve is opened in the reverse direction, and the hydraulic oil in the rod chamber of the hydraulic cylinder flows back to the variable hydraulic pump; When the hydraulic cylinder is in a retracted state and the load direction is opposite to the movement direction of the hydraulic cylinder, the servo motor is controlled to drive the variable hydraulic pump to move in the opposite direction to drive the hydraulic oil to flow, and the hydraulic oil enters the rod chamber of the hydraulic cylinder from the second oil port of the variable hydraulic pump through the second hydraulically controlled one-way valve; the oil outlet of the first one-way valve is controlled by the first reversing valve to connect the control oil port of the first hydraulically controlled one-way valve and the control oil port of the second hydraulically controlled one-way valve, and the high-pressure hydraulic oil in the rod chamber of the hydraulic cylinder enters the control oil port of the first hydraulically controlled one-way valve, and the first hydraulically controlled one-way valve is opened in the reverse direction, and the hydraulic oil in the rodless chamber of the hydraulic cylinder flows back to the variable hydraulic pump; When the hydraulic cylinder is in a retracted state and the load direction is the same as the movement direction of the hydraulic cylinder, the oil outlet of the first check valve and the oil outlet of the second check valve are controlled by the first reversing valve to connect the control oil outlet of the first hydraulically controlled check valve and the control oil outlet of the second hydraulically controlled check valve, and the high-pressure hydraulic oil in the rodless cavity of the hydraulic cylinder enters the control oil outlet of the first hydraulically controlled check valve. The first hydraulically controlled check valve opens in reverse, and the high-pressure hydraulic oil in the rodless cavity of the hydraulic cylinder flows to the variable hydraulic pump. The high-pressure hydraulic oil drives the variable hydraulic pump to move in reverse to drive the hydraulic oil to flow. The hydraulic oil enters the rod cavity of the hydraulic cylinder from the second oil outlet of the variable hydraulic pump through the second hydraulically controlled check valve; the variable hydraulic pump drives the servo motor to rotate to generate electricity and stores it in the energy storage battery.

[0018] Furthermore, the excavator pump-controlled direct-drive distributed hydraulic system also includes a third control one-way valve, a fourth control one-way valve and an accumulator; the oil inlet of the third control one-way valve and the oil inlet of the fourth control one-way valve are connected to the accumulator; the first oil port of the variable hydraulic pump is connected to the oil outlet of the third control one-way valve through an oil circuit, and the first oil port of the variable hydraulic pump is connected to the control oil port of the fourth control one-way valve through an oil circuit; the second oil port of the variable hydraulic pump is connected to the oil outlet of the fourth control one-way valve through an oil circuit, and the second oil port of the variable hydraulic pump is connected to the control oil port of the third control one-way valve through an oil circuit; When the hydraulic cylinder is in an extended state and the load direction is the same as the movement direction of the hydraulic cylinder, the high-pressure hydraulic oil at the second oil port of the variable hydraulic pump enters the control oil port of the third hydraulic-controlled one-way valve, the third hydraulic-controlled one-way valve opens in the reverse direction, and the accumulator replenishes the hydraulic oil for the hydraulic cylinder through the third hydraulic-controlled one-way valve; When the hydraulic cylinder is in an extended state and the load direction is opposite to the movement direction of the hydraulic cylinder, the high-pressure hydraulic oil at the first oil port of the variable hydraulic pump enters the control oil port of the fourth hydraulic-controlled one-way valve, the fourth hydraulic-controlled one-way valve opens in the reverse direction, and the accumulator replenishes the hydraulic oil for the hydraulic cylinder through the fourth hydraulic-controlled one-way valve; When the hydraulic cylinder is in a retracted state and the load direction is opposite to the movement direction of the hydraulic cylinder, the high-pressure hydraulic oil at the second oil port of the variable hydraulic pump enters the control oil port of the third hydraulic-controlled one-way valve, and the third hydraulic-controlled one-way valve opens in the reverse direction to replenish the hydraulic oil in the accumulator; When the hydraulic cylinder is in a retracted state and the load direction is the same as the movement direction of the hydraulic cylinder, the high-pressure hydraulic oil at the first oil port of the variable hydraulic pump enters the control oil port of the fourth hydraulically controlled one-way valve, and the fourth hydraulically controlled one-way valve opens in reverse to replenish the hydraulic oil to the accumulator.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The present invention utilizes a pump-controlled hydraulic system to replace a traditional valve-controlled hydraulic system, thereby reducing the throttling loss of the system through the pump-controlled system; a distributed system is used to replace a centralized system, thereby eliminating the throttling loss caused by load differences in the centralized system; a servo motor is used to drive a variable displacement pump, thereby broadening the flow control range of the hydraulic system and reducing the overflow loss of the hydraulic system.

[0020] The present invention can convert the potential energy of the load into electrical energy and store it in a power battery by opening the hydraulically controlled one-way valve, thereby realizing energy recovery of the gravity potential energy of the excavator; the hydraulically controlled one-way valve is turned on during operation, and when the actuator load needs to be maintained, the hydraulically controlled one-way valve can be closed by a control valve to realize the load maintenance function; energy recovery of the gravity potential energy of the excavator can improve endurance. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a structural diagram of an excavator pump-controlled direct-drive distributed hydraulic system provided in this embodiment 1; Figure 2 is a first working condition control principle diagram of the oil cylinder drive unit provided in this embodiment 2; Figure 3 is a second working condition control principle diagram of the oil cylinder drive unit provided in this embodiment 2; Figure 4 is a third working condition control principle diagram of the oil cylinder drive unit provided in the second embodiment; Figure 5is a fourth working condition control principle diagram of the oil cylinder drive unit provided in the second embodiment; Figure 6 This is a control principle diagram of the travel drive unit provided in this embodiment 2.

[0022] In the figure, 01 is the cylinder drive unit, 1 is the servo motor, 2 is the variable hydraulic pump, 3 is the third hydraulically controlled one-way valve, 4 is the first hydraulically controlled one-way valve, 5 is the first reversing valve, 6 is the first overflow valve, 7 is the first one-way valve, 8 is the rodless chamber, 9 is the rod chamber, 10 is the second one-way valve, 11 is the second overflow valve, 12 is the second hydraulically controlled one-way valve, 13 is the accumulator, and 14 is the fourth hydraulically controlled one-way valve; 02 is the travel drive unit, 21 is the fixed displacement hydraulic pump, 22 is the travel hydraulic motor, 23 is the second reversing valve, 24 is the third overflow valve, 25 is the cooler, 26 is the fourth overflow valve, 27 is the fifth overflow valve, 28 is the oil replenishment pump, 29 is the third one-way valve, 210 is the fourth one-way valve, and 211 is the high-speed motor. DETAILED DESCRIPTION

[0023] 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.

[0024] It should be noted that in the description of the present invention, the directions or positional relationships indicated by the terms "front", "rear", "left", "right", "up", "down", "inside", "outside", etc. are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention rather than requiring the present invention to be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. The terms "front", "rear", "left", "right", "up", and "down" used in the description of the present invention refer to the directions in the accompanying drawings, and the terms "inside" and "outside" refer to the directions toward or away from the geometric center of a specific component, respectively.

[0025] Example 1

[0026] like Figure 1 As shown, a pump-controlled direct-drive distributed hydraulic system for an excavator includes a hydraulic cylinder and a cylinder drive unit for driving a boom, a bucket or a dipper rod; The cylinder drive unit 01 includes a servo motor 1 and a variable hydraulic pump 2 which are connected in a transmission manner. The servo motor 1 is electrically connected to an energy storage battery. The first oil port of the variable hydraulic pump 2 is connected to the oil inlet of the first hydraulically controlled one-way valve 4 through an oil circuit. The oil outlet of the first hydraulically controlled one-way valve 4 is connected to the rodless chamber 8 of the hydraulic cylinder through an oil circuit. The rod chamber 9 of the hydraulic cylinder is connected to the oil inlet of the second hydraulically controlled one-way valve 12 through an oil circuit. The oil outlet of the second hydraulically controlled one-way valve 12 is connected to the second oil port of the variable hydraulic pump 2 through an oil circuit. The rodless chamber 8 of the hydraulic cylinder is connected in sequence with the oil inlet of the first one-way valve 7, the oil outlet of the first one-way valve 7 is connected with the oil outlet of the second one-way valve 10, and the oil inlet of the second one-way valve 10 is connected with the rod chamber 9 of the hydraulic cylinder; the oil outlet of the first one-way valve 7 and the oil outlet of the second one-way valve 10 are connected to the control oil port of the first hydraulically controlled one-way valve 4 and the control oil port of the second hydraulically controlled one-way valve 12 through the first reversing valve 5.

[0027] The oil inlet of the third control one-way valve 3 and the oil inlet of the fourth control one-way valve 14 are connected to the accumulator 13; the first oil port of the variable hydraulic pump 2 is connected to the oil outlet of the third control one-way valve 3 through an oil circuit, and the first oil port of the variable hydraulic pump 2 is connected to the control oil port of the fourth control one-way valve 14 through an oil circuit; the second oil port of the variable hydraulic pump 2 is connected to the oil outlet of the fourth control one-way valve 14 through an oil circuit, and the second oil port of the variable hydraulic pump 2 is connected to the control oil port of the third control one-way valve 3 through an oil circuit.

[0028] The oil outlet of the first hydraulically controlled one-way valve 4 is connected to the oil inlet of the third control one-way valve 3 and the oil inlet of the fourth control one-way valve 14 through the first relief valve 6. The oil inlet of the second hydraulically controlled one-way valve 12 is connected to the oil inlet of the third control one-way valve 3 and the oil inlet of the fourth control one-way valve 14 through the second relief valve 11. The oil outlet of the first relief valve 6 and the oil outlet of the second relief valve 11 are connected to the control oil port of the first hydraulically controlled one-way valve 4 and the control oil port of the second hydraulically controlled one-way valve 12 through the first reversing valve 5.

[0029] The first reversing valve 5 is set as a two-position three-way solenoid valve. When the first reversing valve 5 is in the first working position, the oil outlet of the first check valve 7 and the oil outlet of the second check valve 10 are connected to the control oil port of the first hydraulically controlled check valve 4 and the control oil port of the second hydraulically controlled check valve 12; when the first reversing valve 5 is in the second working position, the oil outlet of the first overflow valve 6 and the oil outlet of the second overflow valve 11 are connected to the control oil port of the first hydraulically controlled check valve 4 and the control oil port of the second hydraulically controlled check valve 12.

[0030] The variable hydraulic pump is controlled to drive the hydraulic system actuator to move according to the working conditions. The variable hydraulic pump can also be used as a motor to recover the potential energy of the hydraulic cylinder and drive the servo motor to reverse and generate electricity. Since the excavator's operating hydraulic cylinder is an asymmetric cylinder, the accumulator 13 is connected to the low-pressure circuit of the hydraulic system to replenish and supply oil, so that the oil suction and discharge volume of the variable hydraulic pump are matched with the required flow of the hydraulic cylinder; the first reversing valve 5 and the first check valve 7 and the second check valve 10 ensure the connection and disconnection of the circuit to realize the load holding function of the operating cylinder; the first overflow valve 6 and the second overflow valve 11 are used as safety valves of the cylinder drive unit 01 to ensure system safety.

[0031] The excavator pump-controlled direct-drive distributed hydraulic system also includes a travel drive unit 02, which is equipped with a high-speed motor 211, a fixed-displacement hydraulic pump 21 and a travel hydraulic motor 22; the high-speed motor 211 drives the fixed-displacement hydraulic pump 21 to move; the fixed-displacement hydraulic pump 21 drives the travel hydraulic motor 22 to move, and the travel hydraulic motor 22 drives the travel mechanism of the excavator to move.

[0032] The oil outlet of the quantitative hydraulic pump 21 is connected to the oil inlet of the travel hydraulic motor 22, and the oil outlet of the travel hydraulic motor 22 is connected to the oil inlet of the quantitative hydraulic pump 21; the oil inlet of the travel hydraulic motor 22 and the oil outlet of the travel hydraulic motor 22 are connected to the oil tank through the second reversing valve 23; the second reversing valve 23 is set as a three-position three-way solenoid valve, when the second reversing valve 23 is in the first position, the oil inlet of the travel hydraulic motor 11 is connected to the oil tank; when the second reversing valve 23 is in the second position, the oil inlet of the travel hydraulic motor 11 and the oil tank, and the oil inlet of the travel hydraulic motor 11 and the oil tank are disconnected; when the second reversing valve 23 is in the third position, the oil outlet of the travel hydraulic motor 11 is connected to the oil tank. A third overflow valve 24 and a cooler 25 are provided on the oil path between the second reversing valve 23 and the oil tank.

[0033] The travel drive unit 02 also includes a fourth overflow valve 26 and a fifth overflow valve 27; the oil outlet of the quantitative hydraulic pump 21 is connected to the oil inlet of the fourth overflow valve 26, and the oil outlet of the fourth overflow valve 26 is connected to the oil inlet of the quantitative hydraulic pump 21 in sequence; the oil inlet of the quantitative hydraulic pump 21 is connected to the oil inlet of the fifth overflow valve 27, and the oil outlet of the fifth overflow valve 27 is connected to the oil outlet of the quantitative hydraulic pump 21 in sequence.

[0034] The travel drive unit also includes an oil replenishment pump 28, the oil inlet of the oil replenishment pump 28 is connected to the oil tank; the oil outlet of the oil replenishment pump 28 is connected to the oil inlet of the third one-way valve 29 and the oil inlet of the fourth one-way valve 210 through an oil circuit; the oil outlet of the third one-way valve 29 is connected to the oil inlet of the travel hydraulic motor 22, and the oil outlet of the fourth one-way valve 210 is connected to the oil inlet of the quantitative hydraulic pump 21.

[0035] The travel drive unit drives the quantitative hydraulic pump 21 to drive the travel hydraulic motor 22 through the high-speed motor 211, and the oil replenishment pump 28 replenishes oil for the travel drive unit through the one-way valve. The oil in the travel drive unit passes through the second reversing valve and the cooler and returns to the oil tank for cooling to ensure the continuous operation of the system.

[0036] Example 2

[0037] like Figures 2 to 6As shown, a control method for an excavator pump-controlled direct-drive distributed hydraulic system is applied to the excavator pump-controlled direct-drive distributed hydraulic system described in Example 1. The control method includes: like Figure 2 As shown, when the hydraulic cylinder is in the extended state, and the load direction is the same as the movement direction of the hydraulic cylinder, it is recorded as the hydraulic cylinder is in the first working condition, and the oil outlet of the first check valve 7 and the oil outlet of the second check valve 10 are controlled by the first reversing valve 5 to connect the control oil port of the first hydraulically controlled check valve 4 and the control oil port of the second hydraulically controlled check valve 12, and the high-pressure hydraulic oil in the rod chamber 9 of the hydraulic cylinder enters the control oil port of the second hydraulically controlled check valve 12, and the second hydraulically controlled check valve 12 is opened in reverse, and the high-pressure hydraulic oil in the rod chamber 9 of the hydraulic cylinder flows to the variable hydraulic pump 2, and the high-pressure hydraulic oil drives the variable hydraulic pump 2 to move forward to drive the hydraulic oil to flow, and the hydraulic oil enters the rodless chamber 8 of the hydraulic cylinder from the first oil port of the variable hydraulic pump 2 through the first hydraulically controlled check valve 4; the variable hydraulic pump 2 drives the servo motor 1 to rotate to generate electricity and store it in the energy storage battery; The high-pressure hydraulic oil at the second oil port of the variable hydraulic pump 2 enters the control oil port of the third hydraulically controlled one-way valve 3, the third hydraulically controlled one-way valve 3 opens in the reverse direction, and the accumulator 13 replenishes the hydraulic oil for the hydraulic cylinder through the third hydraulically controlled one-way valve 3.

[0038] like Figure 3 As shown, when the hydraulic cylinder is in the extended state and the load direction is opposite to the movement direction of the hydraulic cylinder, it is recorded as the hydraulic cylinder is in the second working condition, and the servo motor 1 is controlled to drive the variable hydraulic pump 2 to move forward to drive the hydraulic oil to flow, and the hydraulic oil enters the rodless chamber 8 of the hydraulic cylinder after passing through the first hydraulically controlled one-way valve 4 from the first oil port of the variable hydraulic pump 2; the oil outlet of the first one-way valve 7 and the oil outlet of the second one-way valve 10 are controlled by the first reversing valve 5 to connect the control oil port of the first hydraulically controlled one-way valve 4 and the control oil port of the second hydraulically controlled one-way valve 12, and the high-pressure hydraulic oil in the rodless chamber 8 of the hydraulic cylinder enters the control oil port of the second hydraulically controlled one-way valve 12, and the second hydraulically controlled one-way valve 12 is opened in the reverse direction, and the hydraulic oil in the rod chamber 9 of the hydraulic cylinder flows back to the variable hydraulic pump 2; The high-pressure hydraulic oil at the first oil port of the variable hydraulic pump 2 enters the control oil port of the fourth hydraulically controlled one-way valve 14, the fourth hydraulically controlled one-way valve 14 opens in the reverse direction, and the accumulator 13 replenishes the hydraulic oil for the hydraulic cylinder through the fourth hydraulically controlled one-way valve 14.

[0039] like Figure 4As shown, when the hydraulic cylinder is in a retracted state and the load direction is opposite to the movement direction of the hydraulic cylinder, it is recorded as the hydraulic cylinder is in the third working condition, and the servo motor 1 is controlled to drive the variable hydraulic pump 2 to move in the reverse direction to drive the hydraulic oil to flow, and the hydraulic oil enters the rod chamber 9 of the hydraulic cylinder after passing through the second hydraulically controlled one-way valve 12 from the second oil port of the variable hydraulic pump 2; the oil outlet of the first one-way valve 7 and the oil outlet of the second one-way valve 10 are controlled by the first reversing valve 5 to connect the control oil port of the first hydraulically controlled one-way valve 4 and the control oil port of the second hydraulically controlled one-way valve 12, and the high-pressure hydraulic oil in the rod chamber of the hydraulic cylinder enters the control oil port of the first hydraulically controlled one-way valve 4, and the first hydraulically controlled one-way valve 4 is opened in the reverse direction, and the hydraulic oil in the rodless chamber 8 of the hydraulic cylinder flows back to the variable hydraulic pump 2; The high-pressure hydraulic oil at the second oil port of the variable hydraulic pump 2 enters the control oil port of the third hydraulically controlled one-way valve 3 , and the third hydraulically controlled one-way valve 3 opens in the reverse direction to replenish the hydraulic oil in the accumulator 13 .

[0040] like Figure 5 As shown, when the hydraulic cylinder is in a retracted state and the load direction is the same as the movement direction of the hydraulic cylinder, it is recorded as the hydraulic cylinder being in the fourth working condition; the oil outlet of the first check valve 7 and the oil outlet of the second check valve 10 are controlled by the first reversing valve 5 to connect to the control oil port of the first hydraulically controlled check valve 4 and the control oil port of the second hydraulically controlled check valve 12, and the high-pressure hydraulic oil in the rodless chamber 8 of the hydraulic cylinder enters the control oil port of the first hydraulically controlled check valve 4, and the first hydraulically controlled check valve 4 is opened in reverse, and the high-pressure hydraulic oil in the rodless chamber 8 of the hydraulic cylinder flows to the variable hydraulic pump 2, and the high-pressure hydraulic oil drives the variable hydraulic pump 2 to move in reverse to drive the hydraulic oil to flow, and the hydraulic oil enters the rod chamber 9 of the hydraulic cylinder after passing through the second hydraulically controlled check valve 12 from the second oil port of the variable hydraulic pump 2; the variable hydraulic pump 2 drives the servo motor 1 to rotate to generate electricity and store it in the energy storage battery; The high-pressure hydraulic oil at the first oil port of the variable hydraulic pump 2 enters the control oil port of the fourth hydraulically controlled one-way valve 4 , and the fourth hydraulically controlled one-way valve 4 opens in the reverse direction to replenish the hydraulic oil in the accumulator 13 .

[0041] In this embodiment, by opening the hydraulically controlled one-way valve, the potential energy of the load can be converted into electrical energy and stored in the power battery, thereby realizing the energy recovery of the excavator's gravitational potential energy; the hydraulically controlled one-way valve is turned on during operation, and when the actuator needs to maintain the load, the hydraulically controlled one-way valve can be closed by the control valve to realize the load holding function; energy recovery of the excavator's gravitational potential energy improves endurance.

[0042] like Figure 6As shown, the high-speed motor 211 drives the quantitative hydraulic pump 21 to move; the quantitative hydraulic pump 21 drives the travel hydraulic motor 22 to move, and the travel hydraulic motor 22 drives the travel mechanism of the excavator to move; the oil replenishment pump 28 replenishes oil for the travel drive unit through a one-way valve, and the oil in the travel drive unit returns to the oil tank through the second reversing valve and the cooler for cooling. The fourth overflow valve 26 and the fifth overflow valve 27 are used as safety valves of the cylinder drive unit 01 to ensure the continuous operation of the system.

[0043] 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. An excavator pump-controlled direct-drive distributed hydraulic system, characterized in that: It includes a hydraulic cylinder and a cylinder drive unit for driving a boom, a bucket or an arm; The oil cylinder drive unit comprises a servo motor and a variable hydraulic pump which are connected in a transmission manner, the servo motor is electrically connected to the energy storage battery, the first oil port of the variable hydraulic pump is connected to the oil inlet of the first hydraulically controlled one-way valve through an oil circuit, the oil outlet of the first hydraulically controlled one-way valve is connected to the rodless chamber of the hydraulic cylinder through an oil circuit; the rod chamber of the hydraulic cylinder is connected to the oil inlet of the second hydraulically controlled one-way valve through an oil circuit, and the oil outlet of the second hydraulically controlled one-way valve is connected to the second oil port of the variable hydraulic pump through an oil circuit; The rodless chamber of the hydraulic cylinder is connected in sequence to the oil inlet of the first one-way valve, the oil outlet of the first one-way valve is connected to the oil outlet of the second one-way valve, and the oil inlet of the second one-way valve is connected to the rod chamber of the hydraulic cylinder; The oil outlet of the first one-way valve and the oil outlet of the second one-way valve are connected to the control oil port of the first hydraulically controlled one-way valve and the control oil port of the second hydraulically controlled one-way valve through the first reversing valve.

2. The excavator pump-controlled direct-drive distributed hydraulic system according to claim 1, characterized in that: It also includes a third control check valve, a fourth control check valve and an accumulator; the oil inlet of the third control check valve and the oil inlet of the fourth control check valve are connected to the accumulator; the first oil port of the variable hydraulic pump is connected to the oil outlet of the third control check valve through an oil circuit, and the first oil port of the variable hydraulic pump is connected to the control oil port of the fourth control check valve through an oil circuit; the second oil port of the variable hydraulic pump is connected to the oil outlet of the fourth control check valve through an oil circuit, and the second oil port of the variable hydraulic pump is connected to the control oil port of the third control check valve through an oil circuit.

3. The excavator pump-controlled direct-drive distributed hydraulic system according to claim 2, characterized in that: The oil outlet of the first hydraulically controlled one-way valve is connected to the oil inlet of the third control one-way valve and the oil inlet of the fourth control one-way valve through the first overflow valve.

4. The excavator pump-controlled direct-drive distributed hydraulic system according to claim 3, characterized in that: The oil inlet of the second hydraulically controlled one-way valve is connected to the oil inlet of the third control one-way valve and the oil inlet of the fourth control one-way valve through the second overflow valve.

5. The excavator pump-controlled direct-drive distributed hydraulic system according to claim 4, characterized in that: The oil outlet of the first relief valve and the oil outlet of the second relief valve are connected to the control oil port of the first hydraulically controlled one-way valve and the control oil port of the second hydraulically controlled one-way valve through the first reversing valve.

6. The excavator pump-controlled direct-drive distributed hydraulic system according to claim 5, characterized in that: The first reversing valve is set as a two-position three-way solenoid valve. When the first reversing valve is in the first working position, the oil outlet of the first one-way valve and the oil outlet of the second one-way valve are connected to the control oil port of the first hydraulically controlled one-way valve and the control oil port of the second hydraulically controlled one-way valve; when the first reversing valve is in the second working position, the oil outlet of the first overflow valve and the oil outlet of the second overflow valve are connected to the control oil port of the first hydraulically controlled one-way valve and the control oil port of the second hydraulically controlled one-way valve.

7. The excavator pump-controlled direct-drive distributed hydraulic system according to claim 1, characterized in that: It also includes a travel drive unit, which is equipped with a high-speed motor, a quantitative hydraulic pump and a travel hydraulic motor; the high-speed motor drives the quantitative hydraulic pump to move; the quantitative hydraulic pump drives the travel hydraulic motor to move, and the travel hydraulic motor drives the travel mechanism of the excavator to move.

8. The excavator pump-controlled direct-drive distributed hydraulic system according to claim 7, characterized in that: The oil outlet of the quantitative hydraulic pump is connected with the oil inlet of the travel hydraulic motor, and the oil outlet of the travel hydraulic motor is connected with the oil inlet of the quantitative hydraulic pump; the oil inlet of the travel hydraulic motor and the oil outlet of the travel hydraulic motor are connected to the oil tank through the second reversing valve; the second reversing valve is set as a three-position three-way solenoid valve, and when the second reversing valve is in the first position, the oil inlet of the travel hydraulic motor is connected to the oil tank; when the second reversing valve is in the second position, the oil inlet of the travel hydraulic motor and the oil tank, and the oil inlet of the travel hydraulic motor and the oil tank are disconnected; when the second reversing valve is in the third position, the oil outlet of the travel hydraulic motor is connected to the oil tank.

9. The excavator pump-controlled direct-drive distributed hydraulic system according to claim 8, characterized in that: A third overflow valve and a cooler are provided on the oil circuit between the second reversing valve and the oil tank.

10. The excavator pump-controlled direct-drive distributed hydraulic system according to claim 7, characterized in that: The travel drive unit also includes a fourth overflow valve and a fifth overflow valve; the oil outlet of the quantitative hydraulic pump is connected to the oil inlet of the fourth overflow valve, and the oil outlet of the fourth overflow valve is connected to the oil inlet of the quantitative hydraulic pump in sequence; the oil inlet of the quantitative hydraulic pump is connected to the oil inlet of the fifth overflow valve, and the oil outlet of the fifth overflow valve is connected to the oil outlet of the quantitative hydraulic pump in sequence.

11. The excavator pump-controlled direct-drive distributed hydraulic system according to claim 7, characterized in that: The travel drive unit also includes an oil replenishment pump, the oil inlet of the oil replenishment pump is connected to the oil tank; the oil outlet of the oil replenishment pump is connected to the oil inlet of the third one-way valve and the oil inlet of the fourth one-way valve through an oil circuit; the oil outlet of the third one-way valve is connected to the oil inlet of the travel hydraulic motor, and the oil outlet of the fourth one-way valve is connected to the oil inlet of the quantitative hydraulic pump.

12. The control method of the excavator pump-controlled direct-drive distributed hydraulic system according to any one of claims 1 to 11, characterized in that: include: When the hydraulic cylinder is in an extended state and the load direction is the same as the movement direction of the hydraulic cylinder, the oil outlet of the first check valve and the oil outlet of the second check valve are controlled by the first reversing valve to connect the control oil outlet of the first hydraulically controlled check valve and the control oil outlet of the second hydraulically controlled check valve, and the high-pressure hydraulic oil in the rod chamber of the hydraulic cylinder enters the control oil outlet of the second hydraulically controlled check valve. The second hydraulically controlled check valve is opened in reverse, and the high-pressure hydraulic oil in the rod chamber of the hydraulic cylinder flows to the variable hydraulic pump. The high-pressure hydraulic oil drives the variable hydraulic pump to move forward to drive the hydraulic oil to flow. The hydraulic oil enters the rodless chamber of the hydraulic cylinder from the first oil outlet of the variable hydraulic pump through the first hydraulically controlled check valve; the variable hydraulic pump drives the servo motor to rotate to generate electricity and stores it in the energy storage battery; When the hydraulic cylinder is in an extended state and the load direction is opposite to the movement direction of the hydraulic cylinder, the servo motor is controlled to drive the variable hydraulic pump to move forward to drive the hydraulic oil to flow, and the hydraulic oil enters the rodless chamber of the hydraulic cylinder from the first oil port of the variable hydraulic pump through the first hydraulically controlled one-way valve; the oil outlet of the first one-way valve is controlled by the first reversing valve to connect the control oil port of the first hydraulically controlled one-way valve and the control oil port of the second hydraulically controlled one-way valve, and the high-pressure hydraulic oil in the rodless chamber of the hydraulic cylinder enters the control oil port of the second hydraulically controlled one-way valve, and the second hydraulically controlled one-way valve is opened in the reverse direction, and the hydraulic oil in the rod chamber of the hydraulic cylinder flows back to the variable hydraulic pump; When the hydraulic cylinder is in a retracted state and the load direction is opposite to the movement direction of the hydraulic cylinder, the servo motor is controlled to drive the variable hydraulic pump to move in the opposite direction to drive the hydraulic oil to flow, and the hydraulic oil enters the rod chamber of the hydraulic cylinder from the second oil port of the variable hydraulic pump through the second hydraulically controlled one-way valve; the oil outlet of the first one-way valve is controlled by the first reversing valve to connect the control oil port of the first hydraulically controlled one-way valve and the control oil port of the second hydraulically controlled one-way valve, and the high-pressure hydraulic oil in the rod chamber of the hydraulic cylinder enters the control oil port of the first hydraulically controlled one-way valve, and the first hydraulically controlled one-way valve is opened in the reverse direction, and the hydraulic oil in the rodless chamber of the hydraulic cylinder flows back to the variable hydraulic pump; When the hydraulic cylinder is in a retracted state and the load direction is the same as the movement direction of the hydraulic cylinder, the oil outlet of the first check valve and the oil outlet of the second check valve are controlled by the first reversing valve to connect the control oil outlet of the first hydraulically controlled check valve and the control oil outlet of the second hydraulically controlled check valve, and the high-pressure hydraulic oil in the rodless cavity of the hydraulic cylinder enters the control oil outlet of the first hydraulically controlled check valve. The first hydraulically controlled check valve opens in reverse, and the high-pressure hydraulic oil in the rodless cavity of the hydraulic cylinder flows to the variable hydraulic pump. The high-pressure hydraulic oil drives the variable hydraulic pump to move in reverse to drive the hydraulic oil to flow. The hydraulic oil enters the rod cavity of the hydraulic cylinder from the second oil outlet of the variable hydraulic pump through the second hydraulically controlled check valve; the variable hydraulic pump drives the servo motor to rotate to generate electricity and stores it in the energy storage battery.

13. The control method according to claim 12, characterized in that: The excavator pump-controlled direct-drive distributed hydraulic system also includes a third control check valve, a fourth control check valve and an accumulator; the oil inlet of the third control check valve and the oil inlet of the fourth control check valve are connected to the accumulator; the first oil port of the variable hydraulic pump is connected to the oil outlet of the third control check valve through an oil circuit, and the first oil port of the variable hydraulic pump is connected to the control oil port of the fourth control check valve through an oil circuit; the second oil port of the variable hydraulic pump is connected to the oil outlet of the fourth control check valve through an oil circuit, and the second oil port of the variable hydraulic pump is connected to the control oil port of the third control check valve through an oil circuit; When the hydraulic cylinder is in an extended state and the load direction is the same as the movement direction of the hydraulic cylinder, the high-pressure hydraulic oil at the second oil port of the variable hydraulic pump enters the control oil port of the third hydraulic-controlled one-way valve, the third hydraulic-controlled one-way valve opens in the reverse direction, and the accumulator replenishes the hydraulic oil for the hydraulic cylinder through the third hydraulic-controlled one-way valve; When the hydraulic cylinder is in an extended state and the load direction is opposite to the movement direction of the hydraulic cylinder, the high-pressure hydraulic oil at the first oil port of the variable hydraulic pump enters the control oil port of the fourth hydraulic-controlled one-way valve, the fourth hydraulic-controlled one-way valve opens in the reverse direction, and the accumulator replenishes the hydraulic oil for the hydraulic cylinder through the fourth hydraulic-controlled one-way valve; When the hydraulic cylinder is in a retracted state and the load direction is opposite to the movement direction of the hydraulic cylinder, the high-pressure hydraulic oil at the second oil port of the variable hydraulic pump enters the control oil port of the third hydraulic-controlled one-way valve, and the third hydraulic-controlled one-way valve opens in the reverse direction to replenish the hydraulic oil in the accumulator; When the hydraulic cylinder is in a retracted state and the load direction is the same as the movement direction of the hydraulic cylinder, the high-pressure hydraulic oil at the first oil port of the variable hydraulic pump enters the control oil port of the fourth hydraulically controlled one-way valve, and the fourth hydraulically controlled one-way valve opens in reverse to replenish the hydraulic oil to the accumulator.

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