Power compensation hydraulic system, control method, and hydraulic excavator

Abstract

The application discloses a power compensation hydraulic system, a control method and a hydraulic excavator, and has the technical scheme that a power compensation pump and an accumulator are added in the hydraulic system of the excavator; during the low-pressure operation stage of the excavator, the power compensation pump injects hydraulic oil into the accumulator; during the excavation stage, the accumulator injects the hydraulic oil into the large cavity of the bucket rod oil cylinder under high pressure, compensates the power of the high-pressure area, and improves the excavation speed of the bucket rod. The application has the characteristics of power compensation and high excavation efficiency.

Description

Technical Field

[0001] This invention relates to a power-compensated hydraulic system, belonging to the field of excavator hydraulic technology applications. Background Technology

[0002] Currently, most hydraulic excavators use constant power hydraulic systems. During the high-pressure phase, the system enters the constant power zone, and as the system pressure increases, the system flow gradually decreases. As the primary action of the excavator, stick digging slows down under heavy loads because it operates in the constant power zone and the system pressure is high. This can even severely reduce operational performance and affect the overall operating speed. Summary of the Invention

[0003] The present invention aims to overcome the above-mentioned defects and provides a power compensation hydraulic system for hydraulic excavators.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] In a first aspect, the present invention discloses a power-compensated hydraulic system, comprising an accumulator, a boom cylinder, or a portal shuttle valve I, a pressure reducing valve I, a hydraulically controlled directional valve I, a hydraulically controlled directional valve II, a hydraulically controlled directional valve III, a main valve, a main pump, a pressure reducing valve II, a speed regulating valve, or a portal shuttle valve II, a check valve, a hydraulic oil tank, a hydraulic handle, a power-compensating pump, and a hydraulically controlled directional valve IV; the suction port of the power-compensating pump is connected to the hydraulic oil tank; the outlet port of the power-compensating pump is connected to the P port of the hydraulically controlled directional valve IV; the A port of the hydraulically controlled directional valve IV is connected to the inlet port of the accumulator, the inlet port of the check valve, and the inlet port of the pressure reducing valve I, respectively; the B port of the hydraulically controlled directional valve IV is connected to the hydraulic oil tank; the hydraulic control port of the hydraulically controlled directional valve IV is connected to the outlet port of the portal shuttle valve I; the outlet port of the check valve is connected to the inlet port of the speed regulating valve; and the outlet port of the speed regulating valve is connected to the inlet port of the hydraulically controlled directional valve II. The outlet of hydraulic directional valve II is connected to the hydraulic control port of hydraulic directional valve II, the inlet of hydraulic directional valve I, and the hydraulic control port of hydraulic directional valve III, respectively; the outlet of hydraulic directional valve I is connected to the large chamber of the boom cylinder; the outlet of pressure reducing valve I is connected to the inlet A of portal shuttle valve II; or the inlet B of portal shuttle valve II is connected to the outlet of pressure reducing valve II; or the outlet of portal shuttle valve II is connected to the inlet B of portal shuttle valve I; or the inlet A of portal shuttle valve I is connected to the outlet B of hydraulic directional valve III; the hydraulic handle control output port is connected to the hydraulic control port of hydraulic directional valve I, the A port of hydraulic directional valve III, and the pilot oil circuit of the boom large chamber control of the main valve, respectively; the T port of hydraulic directional valve III is connected to the hydraulic oil tank; the main pump inputs hydraulic oil to the large chamber of the boom cylinder through the main valve; the outlet of the main pump is connected to the inlet of pressure reducing valve II.

[0006] In some embodiments, a relief valve is also included, with its outlet connected to a hydraulic oil tank and its inlet connected to a power compensation pump.

[0007] In some embodiments, the hydraulic control directional valve I is a two-position two-way hydraulic control directional valve, which is normally closed; when the output control pressure of the hydraulic handle reaches the maximum control pressure, the hydraulic control port of the hydraulic control directional valve I pushes the valve core of the hydraulic control directional valve I to change position.

[0008] In some embodiments, the hydraulic control directional valve II is a two-position two-way hydraulic control directional valve, which is normally closed; when the hydraulic control port of the hydraulic control directional valve II reaches the set pressure at the outlet, it pushes the valve core of the hydraulic control directional valve II to change position.

[0009] In some embodiments, the hydraulic control directional valve III is a two-position three-way hydraulic control directional valve. The normal position is the right position, with port B and port T connected and port A closed; the left position has port A and port B connected and port T closed. When the hydraulic control port of the hydraulic control directional valve III reaches the set pressure at the outlet of the hydraulic control directional valve II, it pushes the valve core of the hydraulic control directional valve III to change position.

[0010] In some embodiments, the hydraulic control directional valve IV is a two-position three-way hydraulic control directional valve. The normal position of the hydraulic control directional valve IV is the left position, in which port P and port A are connected and port B is closed; the right position is in which port P and port B are connected and port A is closed.

[0011] When the following three conditions are met: 1) the accumulator reaches the set pressure; 2) the output pressure of the main pump reaches the set pressure; and 3) the output control pressure of the hydraulic handle reaches the maximum control pressure and the large chamber pressure of the boom cylinder reaches the set pressure, the valve core of the hydraulic control directional valve IV will switch.

[0012] In some embodiments, the conditions for the large chamber output pressure oil of the boom cylinder are: the output control pressure of the hydraulic handle reaches the maximum control pressure and the pressure of the large chamber of the boom cylinder reaches the set pressure.

[0013] In some embodiments, the hydraulic handle is an excavator pilot handle, which outputs control pressure to simultaneously control the excavator main valve to allow oil to enter the large chamber of the stick cylinder.

[0014] Secondly, the present invention discloses a control method based on the above-mentioned power-compensated hydraulic system:

[0015] In the initial state, the system automatically checks whether the accumulator has reached the set pressure P1, the main pump outlet has reached the set pressure P2, and the hydraulic handle output pressure has reached the set pressure P3. If any one of the three conditions is met, the oil circuit from the power compensation pump to the accumulator is cut off, and the power compensation pump is depressurized; otherwise, the power compensation pump continues to replenish oil to the accumulator. Subsequently, the system automatically checks whether the accumulator pressure is greater than the input pressure of the large chamber of the stick cylinder, whether the input pressure of the large chamber of the stick cylinder has reached the set pressure P4, and whether the hydraulic handle output pressure has reached the set pressure P3. If all three conditions are met simultaneously, the accumulator replenishes oil to the large chamber of the stick cylinder to increase the stick digging speed; otherwise, it returns to the initial state to continue determining whether to replenish oil to the accumulator and whether to replenish oil to the large chamber of the stick cylinder.

[0016] Thirdly, the present invention discloses a hydraulic excavator equipped with the aforementioned power compensation hydraulic system.

[0017] Beneficial effects of this invention:

[0018] Because of the above-mentioned solution, when the excavator is operating at low pressure or low power, the power compensation pump inputs hydraulic oil into the accumulator for storage. When digging reaches high pressure, or when the excavator's stick digging speed slows down, the hydraulic oil stored in the accumulator is input into the large chamber of the stick cylinder to increase the stick digging speed. Furthermore, during high-pressure operation, the hydraulic control directional valve IV switches, and the power compensation pump is in an unloaded state, which does not affect the power output of the excavator's original hydraulic system. Therefore, this invention features power compensation and high digging efficiency. Attached Figure Description

[0019] The accompanying drawings, as part of this invention, are provided to further illustrate the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention, but do not constitute an undue limitation thereof. Clearly, the drawings described below are merely some embodiments, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0020] In the attached diagram:

[0021] Figure 1 This is a schematic diagram of the power compensation hydraulic system of the present invention;

[0022] Figure 2 This is the operating logic diagram of the power compensation hydraulic system of the present invention.

[0023] In the diagram: 1 Accumulator, 2 Boom cylinder, 3 or gate shuttle valve I, 4 Pressure reducing valve I, 5 Hydraulic directional valve I, 6 Hydraulic directional valve II, 7 Hydraulic directional valve III, 8 Main valve, 9 Main pump, 10 Pressure reducing valve II, 11 Speed ​​control valve, 12 or gate shuttle valve II, 13 Check valve, 14 Relief valve, 15 Hydraulic oil tank, 16 Hydraulic handle, 17 Power compensation pump, 18 Hydraulic directional valve IV.

[0024] It should be noted that these accompanying drawings and textual descriptions are not intended to limit the scope of the invention in any way, but rather to illustrate the concept of the invention to those skilled in the art by referring to specific embodiments. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0026] like Figure 1As shown, a power compensation hydraulic system for a hydraulic excavator includes an accumulator 1, a boom cylinder 2, a portal shuttle valve I 3, a pressure reducing valve I 4, a hydraulic directional valve I 5, a hydraulic directional valve II 6, a hydraulic directional valve III 7, a main valve 8, a main pump 9, a pressure reducing valve II 10, a speed regulating valve 11, or a portal shuttle valve II 12, a check valve 13, a relief valve 14, a hydraulic oil tank 15, a hydraulic handle 16, a power compensation pump 17, and a hydraulic directional valve IV 18. The power compensation pump 17 has its suction port connected to the hydraulic oil tank 16; the power compensation pump 17 is connected to the inlet of the relief valve 14 and the P port of the hydraulic directional valve IV 18; the outlet of the relief valve 14 is connected to the hydraulic oil tank 15; the A port of the hydraulic directional valve IV 18 is connected to the inlet of the accumulator 1, the inlet of the check valve 13, and the inlet of the pressure reducing valve I 4; the B port of the hydraulic directional valve IV 18 is connected to the hydraulic oil tank 15; the hydraulic control port of the hydraulic directional valve IV 18 is connected to the outlet of the gate shuttle valve I 3; the outlet of the check valve 13 is connected to the inlet of the speed control valve 11; the outlet of the speed control valve 11 is connected to the inlet of the hydraulic directional valve II 6; and the outlet of the hydraulic directional valve II 6 is connected to the hydraulic control port of the hydraulic directional valve II 6, the inlet of the hydraulic directional valve I 5, and the hydraulic directional valve III 6. The hydraulic control port of valve 7 is connected to the hydraulic control port of hydraulic directional valve I5; the outlet of hydraulic directional valve I5 is connected to the large chamber of boom cylinder 2; the outlet of pressure reducing valve I4 is connected to the inlet A of shuttle valve II12; or the inlet B of shuttle valve II12 is connected to the outlet of pressure reducing valve II10; or the outlet of shuttle valve II12 is connected to the inlet B of shuttle valve I3; or the inlet A of shuttle valve I3 is connected to the outlet B of hydraulic directional valve III7; the hydraulic handle 16 controls the output ports to be connected to the hydraulic control port of hydraulic directional valve I5, the A port of hydraulic directional valve III7, and the boom large chamber control pilot oil circuit of main valve 8; the T port of hydraulic directional valve III7 is connected to hydraulic oil tank 11. The hydraulic excavator main pump 9 inputs hydraulic oil to the large chamber of boom cylinder 2 through main valve 8; the outlet of main pump 9 is connected to the inlet of pressure reducing valve II10.

[0027] Further proposed solution: The hydraulic directional valve Ⅳ18 is a two-position three-way hydraulic directional valve. The normal position of the hydraulic directional valve Ⅳ14 is the left position, where port P and port A are connected and port B is closed; the right position is where port P and port B are connected and port A is closed.

[0028] When the following three conditions are met: 1) the accumulator 1 reaches the set pressure; 2) the output pressure of the main pump 9 reaches the set pressure; 3) the output control pressure of the hydraulic handle 16 reaches the maximum control pressure and the large chamber pressure of the boom cylinder reaches the set pressure, the valve core of the hydraulic control directional valve Ⅳ18 will switch.

[0029] A further solution: The conditions for the output pressure oil of the large chamber of the boom cylinder 2 are: the output control pressure of the hydraulic handle 16 reaches the maximum control pressure and the pressure of the large chamber of the boom cylinder 2 reaches the set pressure.

[0030] A further solution: The hydraulic directional valve I5 is a two-position, two-way hydraulic directional valve, normally closed; when the output control pressure of the hydraulic handle 16 reaches the maximum control pressure, the hydraulic control port of the hydraulic directional valve I5 pushes the valve core of the hydraulic directional valve I5 to change position.

[0031] A further solution: The hydraulic directional valve II6 is a two-position, two-way hydraulic directional valve, normally closed; when the hydraulic control port of the hydraulic directional valve II6 reaches the set pressure at the outlet, it pushes the valve core of the hydraulic directional valve II6 to change position.

[0032] A further proposed solution: The hydraulic directional valve III 7 is a two-position, three-way hydraulic directional valve. In its normal position, it is the right position, with ports B and T connected and port A closed. In the left position, ports A and B are connected, and port T is closed. The hydraulic control port of the hydraulic directional valve III 7 pushes the valve core of the hydraulic directional valve III 7 to change position when the outlet pressure of the hydraulic directional valve II 6 reaches the set pressure.

[0033] A further solution: The hydraulic handle 12 is the excavator pilot handle. In this system, the output control pressure simultaneously controls the excavator main valve to allow oil to enter the large chamber of the boom cylinder 2.

[0034] like Figure 2 As shown, the operating logic of the hydraulic excavator's power compensation hydraulic system is as follows: In the initial state, the system automatically checks whether the accumulator 1 has reached the set pressure P1, whether the main oil circuit (i.e., the outlet of the main pump 9) has reached the set pressure P2, and whether the output pressure of the hydraulic handle 16 has reached the set pressure P3. If any one of the three conditions is met, the oil circuit from the power compensation pump 17 to the accumulator 1 is cut off, and the power compensation pump 17 is depressurized; otherwise, the power compensation pump 17 continues to replenish oil to the accumulator 1. Subsequently, the system automatically checks whether the pressure of the accumulator 1 is greater than the input pressure of the large chamber of the stick cylinder 2, whether the input pressure of the large chamber of the stick cylinder 2 has reached the set pressure P4, and whether the output pressure of the hydraulic handle 16 has reached the set pressure P3. If all three conditions are met simultaneously, the accumulator 1 replenishes oil to the large chamber of the stick cylinder 2 to increase the stick digging speed; otherwise, it returns to the initial state and continues to determine whether to replenish oil to the accumulator 1 and whether to replenish oil to the large chamber of the stick cylinder 2.

[0035] In summary, this invention adds a power compensation pump and an accumulator to the excavator's hydraulic system. During the low-pressure operation phase of the excavator, the power compensation pump injects hydraulic oil into the accumulator. During the digging phase, under high-pressure conditions, the accumulator injects hydraulic oil into the large chamber of the stick cylinder, compensating for the power in the high-pressure zone and increasing the stick's digging speed. This invention features power compensation and high digging efficiency.

[0036] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0037] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features found in other embodiments but not others, combinations of features from different embodiments are also within the scope of protection of this invention and form different embodiments. For example, in the embodiments described above, those skilled in the art can use them in combination based on known technical solutions and the technical problems to be solved by this application.

[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-described technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A power-compensated hydraulic system, characterized in that: Includes accumulator, boom cylinder, or portal shuttle valve I, pressure reducing valve I, hydraulic directional valve I, hydraulic directional valve II, hydraulic directional valve III, main valve, main pump, pressure reducing valve II, speed control valve, or portal shuttle valve II, check valve, hydraulic oil tank, hydraulic handle, power compensation pump, hydraulic directional valve IV; The suction port of the power compensation pump is connected to the hydraulic oil tank; the outlet port of the power compensation pump is connected to the P port of the hydraulic directional valve IV; the A port of the hydraulic directional valve IV is connected to the inlet port of the accumulator, the inlet port of the check valve, and the inlet port of the pressure reducing valve I; the B port of the hydraulic directional valve IV is connected to the hydraulic oil tank; the hydraulic control port of the hydraulic directional valve IV is connected to the outlet port of the gate shuttle valve I; the outlet port of the check valve is connected to the inlet port of the speed control valve; the outlet port of the speed control valve is connected to the inlet port of the hydraulic directional valve II; the outlet ports of the hydraulic directional valve II are connected to the hydraulic control ports of the hydraulic directional valve II. The system includes control ports, the inlet of hydraulic directional valve I, and the hydraulic control port of hydraulic directional valve III; the outlet of hydraulic directional valve I is connected to the large chamber of the boom cylinder; the outlet of pressure reducing valve I is connected to the inlet A of either portal shuttle valve II or the inlet B of portal shuttle valve II is connected to the outlet of pressure reducing valve II; or the outlet of portal shuttle valve II is connected to the inlet B of either portal shuttle valve I or the inlet A of portal shuttle valve I is connected to the outlet B of hydraulic directional valve III; the hydraulic handle control output ports are respectively connected to the hydraulic control port of hydraulic directional valve I, the A port of hydraulic directional valve III, and the pilot control oil circuit of the large chamber of the main valve boom; the T port of hydraulic directional valve III is connected to the hydraulic oil tank; the main pump inputs hydraulic oil to the large chamber of the boom cylinder through the main valve; the outlet of the main pump is connected to the inlet of pressure reducing valve II.

2. The power-compensated hydraulic system according to claim 1, characterized in that: It also includes an overflow valve, whose outlet is connected to the hydraulic oil tank and whose inlet is connected to the power compensation pump.

3. The power-compensated hydraulic system according to claim 1, characterized in that: The hydraulic control directional valve I is a two-position, two-way hydraulic control directional valve, normally closed. When the output control pressure of the hydraulic handle reaches the maximum control pressure, the hydraulic control port of the hydraulic directional valve I pushes the valve core of the hydraulic directional valve I to change position.

4. The power-compensated hydraulic system according to claim 1, characterized in that: The hydraulic control directional valve II is a two-position, two-way hydraulic control directional valve, normally closed. When the hydraulic control port of the hydraulic directional valve II reaches the set pressure at the outlet, it pushes the valve core of the hydraulic directional valve II to change position.

5. A power-compensated hydraulic system according to claim 1, characterized in that: The hydraulic control directional valve III is a two-position three-way hydraulic control directional valve. In its normal position, it is in the right position, with port B and port T connected and port A closed; in the left position, port A and port B are connected and port T is closed. When the hydraulic control port of hydraulic directional valve III reaches the set pressure at the outlet of hydraulic directional valve II, it pushes the valve core of hydraulic directional valve III to change position.

6. A power-compensated hydraulic system according to claim 1, characterized in that: The hydraulic control directional valve IV is a two-position three-way hydraulic control directional valve. The normal position of the hydraulic control directional valve IV is the left position, in which port P and port A are connected and port B is closed; in the right position, port P and port B are connected and port A is closed. When the following three conditions are met: 1) the accumulator reaches the set pressure; 2) the output pressure of the main pump reaches the set pressure; and 3) the output control pressure of the hydraulic handle reaches the maximum control pressure and the large chamber pressure of the boom cylinder reaches the set pressure, the valve core of the hydraulic control directional valve IV will switch.

7. A power-compensated hydraulic system according to claim 1, characterized in that: The conditions for the large chamber output pressure oil of the boom cylinder are: the output control pressure of the hydraulic handle reaches the maximum control pressure and the pressure of the large chamber of the boom cylinder reaches the set pressure.

8. A power-compensated hydraulic system according to claim 1, characterized in that: The hydraulic handle is the excavator pilot handle, and its output control pressure simultaneously controls the excavator main valve to allow oil to enter the large chamber of the stick cylinder.

9. A control method for a power-compensated hydraulic system according to any one of claims 1 to 8, characterized in that: In the initial state, the system automatically checks whether the accumulator has reached the set pressure P1, whether the main pump outlet has reached the set pressure P2, and whether the hydraulic handle output pressure has reached the set pressure P3. If any of the three conditions are met, the oil circuit from the power compensation pump to the accumulator is cut off and the power compensation pump is depressurized; otherwise, the power compensation pump continues to replenish oil to the accumulator. The system then automatically checks whether the accumulator pressure is greater than the input pressure of the large chamber of the stick cylinder, whether the input pressure of the large chamber of the stick cylinder reaches the set pressure P4, and whether the output pressure of the hydraulic handle reaches the set pressure P3. If all three conditions are met, the accumulator replenishes oil to the large chamber of the stick cylinder to increase the stick digging speed; otherwise, it returns to the initial state and continues to determine whether to replenish oil to the accumulator and whether to replenish oil to the large chamber of the stick cylinder.

10. A hydraulic excavator, characterized in that: The system is equipped with the power-compensated hydraulic system as described in any one of claims 1 to 8.

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