Hydraulic systems for construction machinery, hydraulic system control methods, and construction machinery

Abstract

This invention belongs to the field of engineering machinery technology and discloses a hydraulic system for engineering machinery, a hydraulic system control method, and the engineering machinery itself. In the hydraulic system of the engineering machinery, the slewing motor is no longer powered by a hydraulic pump, but instead by a first variable pump and a second variable pump. The first variable pump can only provide power to the slewing motor to ensure sufficient power for the slewing motor. The second variable pump can provide power to the slewing motor or to the working equipment of the engineering machinery according to the actual situation. This can balance the pressure required for slewing and other actions, avoid the problem of large pressure differences between slewing and boom, which would lead to large pressure loss, and avoid the problem of slewing dominating the flow distribution, which would affect the speed of the boom during compound actions.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery technology, and in particular to hydraulic systems for engineering machinery, hydraulic system control methods, and engineering machinery. Background Technology

[0002] During operation, excavators typically require the boom, stick, and bucket to work together, as well as to perform travel and slewing operations. Among these, slewing, as the control action of the upper platform, involves frequent compound movements with the boom, stick, and bucket. Therefore, the energy consumption of the slewing hydraulic system accounts for a relatively high proportion of the excavator's hydraulic system.

[0003] The structure of a hydraulic system for an excavator in the prior art is as follows: Figure 1 As shown, the excavator's hydraulic system includes a hydraulic pump 1000, a boom linkage pilot valve 1001, a swing linkage pilot valve 1002, a flow control valve assembly 1003, a boom control cylinder 1006, and a swing motor 1007. The flow control valve assembly 1003 includes a boom linkage 1004 and a swing linkage 1005. Both the boom linkage 1004 and the swing linkage 1005 are solenoid valves. The boom linkage 1004 is connected to the boom control cylinder 1006, and the swing linkage 1005 is connected to the swing motor 1007. The hydraulic pump 1000 provides power to the entire hydraulic system, the boom linkage pilot valve 1001 controls the boom linkage 1004, and the swing linkage pilot valve 1002 controls the swing linkage 1005. When only the boom movement is controlled, the boom coupling pilot valve 1001 independently controls the boom coupling 1004 so that hydraulic fluid can enter the boom control cylinder 1006 through the boom coupling 1004; when only the slewing action is performed, the slewing coupling pilot valve 1002 independently controls the slewing coupling 1005 so that hydraulic fluid can enter the slewing motor 1007 through the slewing coupling 1005; when the boom and slewing actions are combined, the boom coupling pilot valve 1001 and the slewing coupling pilot valve 1002 need to be manually operated to control the speed of the corresponding action, which is not easy to operate.

[0004] In response, existing technology provides another hydraulic system for excavators, the structural diagram of which is shown below. Figure 2As shown, the excavator's hydraulic system includes a hydraulic pump 2000, a pilot solenoid valve 2001, a flow control valve assembly 2002, a boom control cylinder 2005, and a swing motor 2006. The flow control valve assembly 2002 includes a boom coupling 2003 and a swing coupling 2004. Both the boom coupling 2003 and the swing coupling 2004 are solenoid valves. The boom coupling 2003 is connected to the boom control cylinder 2005, and the swing coupling 2004 is connected to the swing motor 2006. The hydraulic pump 2000 provides power to the entire hydraulic system, and the pilot solenoid valve 2001 simultaneously controls both the boom coupling 2003 and the swing coupling 2004. When only the boom movement is controlled, the pilot solenoid valve 2001 independently controls the boom coupling 2003, allowing hydraulic fluid to enter the boom control cylinder 2005 through the boom coupling 2003. When only the slewing motion is performed, the pilot solenoid valve 2001 independently controls the slewing coupling 2004, allowing hydraulic fluid to enter the slewing motor 2006 through the slewing coupling 2004. When performing combined boom and slewing motions, the pilot solenoid valve 2001 achieves precise control of both boom and slewing motions, distributing flow according to actual needs without manual operation, thus improving the operating experience and work efficiency. However, there are still some problems. On the one hand, under some working conditions, the pressure required for slewing and boom differs significantly. For example, the slewing pressure is low when slewing is stable, while the boom lifting pressure is high, resulting in significant pressure loss between the hydraulic pump and the slewing motor during slewing. On the other hand, in the above actions, the slewing motion has the advantage in flow distribution, which will affect the boom speed during combined actions, leading to slower speed or insufficient lifting height, thus affecting the excavator's operating efficiency. Summary of the Invention

[0005] According to one aspect of the present invention, the present invention provides a hydraulic system for construction machinery to solve the problems in existing excavator hydraulic systems, such as the large pressure difference required for slewing and boom, resulting in large pressure loss, and the fact that slewing motion dominates in flow distribution, affecting the speed of the boom during combined motions.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The hydraulic system of construction machinery includes an oil tank, a hydraulic pump, and a rotary motor. The oil tank is connected to the hydraulic pump, which is used to connect to the hydraulic system of the working equipment.

[0008] The hydraulic system of the engineering machinery also includes:

[0009] The variable pump assembly includes a first variable pump and a second variable pump, both of which are connected to the oil tank.

[0010] A rotary control valve assembly includes a first rotary control valve and a second rotary control valve. The first rotary control valve is used to connect or disconnect the first variable pump from the rotary motor. The second rotary control valve is used to connect the second variable pump only to the rotary motor, only to the hydraulic system of the working equipment, or simultaneously to both the rotary motor and the hydraulic system of the working equipment.

[0011] As a preferred embodiment of the hydraulic system for engineering machinery, the first rotary control valve has a first initial state and a first working state. When the first rotary control valve is in the first working state, the first rotary control valve is used to connect the first variable pump to the rotary motor. When the first rotary control valve is in the first initial state, the first rotary control valve is used to disconnect the first variable pump from the rotary motor.

[0012] The second rotary control valve has a second initial state, a second working state, and a combined state. When the second rotary control valve is in the second initial state, the second variable pump is connected only to the hydraulic system of the working equipment. When the second rotary control valve is in the second working state, the second variable pump is connected only to the rotary motor. When the second rotary control valve is in the combined state, the second variable pump is connected to both the rotary motor and the hydraulic system of the working equipment.

[0013] As a preferred embodiment of the hydraulic system for engineering machinery, the rotary motor has a first inlet and a second inlet. When oil enters through the first inlet and flows out through the second inlet, the rotary motor moves in the forward direction. When oil enters through the second inlet and flows out through the first inlet, the rotary motor moves in the reverse direction.

[0014] The first operating state of the first rotary control valve includes a first forward operating state and a first reverse operating state. When the first rotary control valve is in the first forward operating state, the first rotary control valve is used to connect the first variable pump to the first liquid inlet and the second liquid inlet to the oil tank. When the first rotary control valve is in the first reverse operating state, the first rotary control valve is used to connect the first variable pump to the second liquid inlet and the first liquid inlet to the oil tank.

[0015] The second operating state of the second rotary control valve includes a second forward operating state and a second reverse operating state. When the second rotary control valve is in the second forward operating state, the second rotary control valve is used to connect the second variable pump to the first liquid inlet, and the second liquid inlet is connected to the oil tank. When the second rotary control valve is in the second reverse operating state, the second rotary control valve is used to connect the second variable pump to the second liquid inlet, and the first liquid inlet is connected to the oil tank.

[0016] The second rotary control valve has two combined states: a forward combined state and a reverse combined state. When the second rotary control valve is in the forward combined state, it connects the second variable pump to both the first inlet and the hydraulic system of the working equipment. When the second rotary control valve is in the reverse combined state, it connects the second variable pump to both the second inlet and the hydraulic system of the working equipment.

[0017] As a preferred embodiment of the hydraulic system for engineering machinery, it also includes a pilot valve control pump, a first pilot valve group, and a second pilot valve group. The input end of the pilot valve control pump is connected to the oil tank, and both the first pilot valve group and the second pilot valve group are connected to the output end of the pilot valve control pump. The first pilot valve group is used to change the state of the first rotary control valve, and the second pilot valve group is used to change the state of the second rotary control valve.

[0018] As a preferred embodiment of the hydraulic system for construction machinery, multiple first variable pumps are provided, and multiple first variable pumps are simultaneously connected to the first rotary control valve; and / or...

[0019] Multiple second variable pumps are provided, and multiple second variable pumps are simultaneously connected to the second rotary control valve.

[0020] As a preferred embodiment of the hydraulic system for construction machinery, a first check valve is provided between the output end of the first variable pump and the first rotary control valve. The first check valve is configured to allow hydraulic fluid only to be delivered from the output end of the first variable pump to the first rotary control valve; and / or...

[0021] A second check valve is provided between the output end of the second variable pump and the second rotary control valve. The second check valve is configured to allow oil to be delivered from the output end of the second variable pump to the second rotary control valve only.

[0022] According to another aspect of the present invention, a hydraulic system control method is provided, implemented by the above-described hydraulic system of engineering machinery, wherein the first rotary control valve has a first initial state and a first working state. When the first rotary control valve is in the first working state, the first rotary control valve is used to connect the first variable pump to the rotary motor. When the first rotary control valve is in the first initial state, the first rotary control valve is used to disconnect the first variable pump from the rotary motor.

[0023] The second rotary control valve has a second initial state, a second working state, and a combined state. When the second rotary control valve is in the second initial state, the second variable pump is connected only to the hydraulic system of the working equipment. When the second rotary control valve is in the second working state, the second variable pump is connected only to the rotary motor. When the second rotary control valve is in the combined state, the second variable pump is connected to both the rotary motor and the hydraulic system of the working equipment.

[0024] The hydraulic system control method includes:

[0025] S100: Determine whether the construction machinery has a slewing motion requirement and any working motion requirement, the working motion requirement including boom requirement, bucket requirement, stick requirement and travel requirement;

[0026] If the construction machinery requires a slewing motion or any working motion, then proceed to step S200.

[0027] S200: Open the first variable pump and the second variable pump, control the first rotary control valve to enter the first working state, and control the second rotary control valve to enter the combined state.

[0028] As a preferred solution for the hydraulic system control method, in step S100, if the construction machinery has a rotational motion requirement but no working motion requirement, then step S300 is executed.

[0029] S300: Obtain the target rotation speed and determine the magnitude of the target rotation speed compared to the speed threshold;

[0030] If the target rotational speed is not less than the speed threshold, then the first variable pump and the second variable pump are turned on, the first rotational control valve is controlled to enter the first working state, and the second rotational control valve is controlled to enter the second working state.

[0031] If the target rotational speed is less than the speed threshold, then the first variable pump is turned on and the second variable pump is turned off, and the first rotational control valve is controlled to enter the first working state.

[0032] As a preferred solution for the hydraulic system control method, in step S100, if the construction machinery has no need for rotation but has any need for working action, then step S400 is executed.

[0033] S400: Turn off the first variable pump, turn on the second variable pump, and control the second rotary control valve to enter the second initial state.

[0034] According to another aspect of the present invention, construction machinery is provided, including the aforementioned construction machinery hydraulic system, and further including a chassis, a body movably disposed on the chassis, and working equipment disposed on the body, wherein the rotary motor is used to drive the body to rotate relative to the chassis.

[0035] The beneficial effects of this invention are:

[0036] This invention provides a hydraulic system for construction machinery, including an oil tank, a hydraulic pump, and a rotary motor. The oil tank is connected to the hydraulic pump, which is used to connect to the hydraulic system of the working equipment. The hydraulic system also includes a variable displacement pump assembly and a rotary control valve assembly. The variable displacement pump assembly includes a first variable displacement pump and a second variable displacement pump, both of which are connected to the oil tank. The rotary control valve assembly includes a first rotary control valve and a second rotary control valve. The first rotary control valve is used to connect or disconnect the first variable displacement pump from the rotary motor. When the first variable displacement pump is connected to the rotary motor, it can supply oil to the rotary motor to drive the construction machinery to complete the rotary motion. When the first variable displacement pump is disconnected from the rotary motor, it stops supplying oil to the rotary motor to control the construction machinery to stop the rotary motion. The second rotary control valve is used to connect the second variable pump only to the rotary motor, only to the hydraulic system of the working equipment, or simultaneously to both the rotary motor and the hydraulic system of the working equipment. When the second variable pump is only connected to the rotary motor, it can supply oil to the rotary motor. In this case, both the first and second variable pumps can supply oil to the rotary motor simultaneously. When the second variable pump is only connected to the hydraulic system of the working equipment, it can supply oil to the hydraulic system of the working equipment. In this case, both the hydraulic pump and the second variable pump can supply oil to the hydraulic system of the working equipment simultaneously. When the second variable pump is connected to both the rotary motor and the hydraulic system of the working equipment simultaneously, it can supply oil to both the rotary motor and the hydraulic system of the working equipment simultaneously. In this hydraulic system of the construction machinery, the slewing motor is no longer powered by a hydraulic pump, but by a first variable pump and a second variable pump. The first variable pump can only provide power to the slewing motor to ensure sufficient power for the slewing motor. The second variable pump can provide power to the slewing motor or the working equipment of the construction machinery according to the actual situation. This can balance the pressure required for slewing and other actions, avoid the problem of large pressure differences between slewing and boom, which would lead to large pressure loss, and avoid the problem of slewing dominating the flow distribution, which would affect the speed of the boom during compound actions.

[0037] This invention also provides a hydraulic system control method implemented through the aforementioned hydraulic system of construction machinery. In this method, it is determined whether the construction machinery requires a slewing motion or any other working motion. Working motion requirements include boom, bucket, stick, and travel motions. If the construction machinery requires a slewing motion or any other working motion, the first and second variable pumps are activated, and the first slewing control valve is controlled to enter a first working state to provide power to the slewing motor, ensuring sufficient power for the slewing motor. Simultaneously, the second slewing control valve is controlled to enter a combined state. At this time, the second variable pump can simultaneously supply oil to the slewing motor and the hydraulic system of the working equipment to balance the pressure required for slewing and other actions. This avoids a large pressure difference between the slewing and boom requirements, which could lead to significant pressure loss, and prevents the slewing motion from dominating the flow distribution, thus affecting the boom speed during combined actions.

[0038] This invention also provides construction machinery, including the aforementioned hydraulic system, and further including a chassis, a body movably mounted on the chassis, and working equipment mounted on the body. A slewing motor is used to drive the body to rotate relative to the chassis. In this hydraulic system, the slewing motor is no longer powered by a hydraulic pump, but instead by a first variable pump and a second variable pump. The first variable pump can only power the slewing motor to ensure sufficient power, while the second variable pump can power either the slewing motor or the working equipment of the construction machinery, depending on the actual situation. This balances the pressure required for slewing and other actions, avoiding large pressure differences between slewing and boom operations, which could lead to significant pressure loss, and preventing the slewing action from dominating flow distribution and affecting boom speed during combined actions. Attached Figure Description

[0039] Figure 1 This is a structural schematic diagram of an excavator hydraulic system in the prior art;

[0040] Figure 2 This is a schematic diagram of another hydraulic system for excavators in the prior art;

[0041] Figure 3 This is a schematic diagram of the hydraulic system of engineering machinery in an embodiment of the present invention;

[0042] Figure 4 This is a schematic diagram of the structure of the first rotary control valve and the first pilot valve group in an embodiment of the present invention;

[0043] Figure 5 This is a schematic diagram of the structure of the second rotary control valve and the second pilot valve assembly in an embodiment of the present invention.

[0044] Figure 6This is a flowchart of the hydraulic system control method in an embodiment of the present invention. Figure 1 ;

[0045] Figure 7 This is a flowchart of the hydraulic system control method in an embodiment of the present invention. Figure 2 ;

[0046] Figure 8 This is a flowchart of the hydraulic system control method in an embodiment of the present invention. Figure 3 .

[0047] In the picture:

[0048] 1000. Hydraulic pump; 1001. Boom coupling pilot valve; 1002. Slewing coupling pilot valve; 1003. Flow control valve assembly; 1004. Boom coupling; 1005. Slewing coupling; 1006. Boom control cylinder; 1007. Slewing motor;

[0049] 2000. Hydraulic pump; 2001. Pilot solenoid valve; 2002. Flow control valve assembly; 2003. Boom coupling; 2004. Slewing coupling; 2005. Boom control cylinder; 2006. Slewing motor;

[0050] 11. Slewing motor; 12. Flow control valve assembly; 121. Boom linkage; 122. Stick linkage; 123. Bucket linkage; 124. Travel linkage; 125. Straight travel linkage; 126. Multi-function linkage;

[0051] 2. Hydraulic pump;

[0052] 3. Variable pump unit; 31. First variable pump; 32. Second variable pump;

[0053] 4. Rotary control valve assembly; 41. First rotary control valve; 42. Second rotary control valve;

[0054] 5. Fuel tank;

[0055] 6. Pilot valve controls the pump; 61. First pilot valve group; 611. First pilot solenoid valve; 612. Second pilot solenoid valve; 62. Second pilot valve group; 621. Third pilot solenoid valve; 622. Fourth pilot solenoid valve;

[0056] 71. First check valve; 72. Second check valve;

[0057] 81. Electronic control unit; 82. Electronic control handle. Detailed Implementation

[0058] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0059] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0060] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0061] In the description of this embodiment, the terms "upper," "lower," "left," and "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0062] Example 1

[0063] During operation, excavators typically require the boom, stick, and bucket to work together, as well as travel and slewing. Slewing, as the control action of the upper platform, involves frequent compound movements with the boom, stick, and bucket, resulting in a significant portion of the energy consumption in the excavator's hydraulic system. However, existing excavator hydraulic systems suffer from several problems. First, under certain conditions, the pressure required for slewing and boom operation differs considerably. For example, slewing pressure is low during stable operation, while boom lifting pressure is high, leading to substantial pressure loss between the hydraulic pump and the slewing motor during slewing. Second, slewing dominates flow distribution in these actions, affecting boom speed during compound movements, resulting in slower speeds or insufficient lifting height, thus impacting excavator operating efficiency.

[0064] In response, this embodiment provides a hydraulic system for construction machinery to solve the problems in existing excavator hydraulic systems, such as the large pressure difference between the swing and boom, which leads to large pressure loss, and the fact that the swing motion dominates in flow distribution, affecting the boom speed during combined actions. This system can be used in the field of construction machinery technology, specifically in excavators.

[0065] Reference Figure 3The hydraulic system of the construction machinery includes an oil tank 5, a hydraulic pump 2, and a swing motor 11. The oil tank 5 is connected to the hydraulic pump 2, which is used to connect to the hydraulic system of the working equipment. The hydraulic system of the working equipment includes the hydraulic systems of the boom, stick, bucket, and travel system, used to realize the movement of the boom, stick, and bucket, as well as the travel of the construction machinery. In this embodiment, the hydraulic system of the construction machinery includes a flow control valve group 12, which includes a boom coupling 121, a stick coupling 122, a bucket coupling 123, and a travel coupling 124. The boom coupling 121 connects or disconnects the power transmission path between the hydraulic pump 2 and the boom cylinder; the stick coupling 122 connects or disconnects the power transmission path between the hydraulic pump 2 and the stick cylinder; the bucket coupling 123 connects or disconnects the power transmission path between the hydraulic pump 2 and the bucket cylinder; and the travel coupling 124 connects or disconnects the power transmission path between the hydraulic pump 2 and the travel motor. In this embodiment, two hydraulic pumps 2 are provided, as are two boom couplings 121, two stick couplings 122, two bucket couplings 123, and two travel couplings 124. Furthermore, the flow control valve assembly 12 includes a linear travel coupling 125 and a multi-function coupling 126. The linear travel coupling 125 connects the hydraulic pump 2 to the power transmission path of the tracks and other structures when the construction machinery is traveling in a straight line. The multi-function coupling 126 enables other functions of the construction machinery. In this embodiment, the output end of one hydraulic pump 2 is sequentially connected to one travel coupling 124, one bucket coupling 123, one boom coupling 121, one multi-function coupling 126, and one stick coupling 122; the output end of the other hydraulic pump 2 is sequentially connected to the linear travel coupling 125, another travel coupling 124, another boom coupling 121, another bucket coupling 123, and another stick coupling 122.

[0066] Continue to refer to Figure 3The hydraulic system of the construction machinery also includes a variable pump assembly 3 and a rotary control valve assembly 4. The variable pump assembly 3 includes a first variable pump 31 and a second variable pump 32, both of which are connected to the oil tank 5. The rotary control valve assembly 4 includes a first rotary control valve 41 and a second rotary control valve 42. The first rotary control valve 41 is used to connect or disconnect the first variable pump 31 from the rotary motor 11. When the first variable pump 31 is connected to the rotary motor 11, oil can be supplied to the rotary motor 11 through the oil tank 5 and the first variable pump 31 to drive the construction machinery to complete the rotary action. When the first variable pump 31 is disconnected from the rotary motor 11, the first variable pump 31 stops supplying oil to the rotary motor 11 to control the construction machinery to stop the rotary action. The second rotary control valve 42 is used to connect the second variable pump 32 only to the rotary motor 11, only to the hydraulic system of the working equipment, or simultaneously to both the rotary motor 11 and the hydraulic system of the working equipment. When the second variable pump 32 is only connected to the rotary motor 11, it can supply oil to the rotary motor 11. At this time, both the first variable pump 31 and the second variable pump 32 supply oil to the rotary motor 11. When the second variable pump 32 is only connected to the hydraulic system of the working equipment, it can supply oil to the hydraulic system of the working equipment. At this time, both the hydraulic pump 2 and the second variable pump 32 supply oil to the hydraulic system of the working equipment. When the second variable pump 32 is simultaneously connected to both the rotary motor 11 and the hydraulic system of the working equipment, it can supply oil to both the rotary motor 11 and the hydraulic system of the working equipment. In this hydraulic system of the construction machinery, the slewing motor 11 is no longer powered by a hydraulic pump, but by a first variable pump 31 and a second variable pump 32. The first variable pump 31 can only provide power to the slewing motor 11 to ensure sufficient power for the slewing motor 11. The second variable pump 32 can provide power to the slewing motor 11, the working equipment of the construction machinery, or both, depending on the actual situation. This balances the pressure required for slewing and other actions, avoiding large pressure differences between slewing and boom, which would lead to large pressure loss, and preventing the slewing action from dominating the flow distribution and affecting the boom speed during compound actions.

[0067] Continue to refer to Figure 3The first rotary control valve 41 has a first initial state and a first working state. When the first rotary control valve 41 is in the first working state, it connects the first variable pump 31 to the rotary motor 11, allowing the first variable pump 31 to supply oil to the rotary motor 11 and drive the construction machinery to complete the rotary motion. When the first rotary control valve 41 is in the first initial state, it disconnects the first variable pump 31 from the rotary motor 11, stopping the first variable pump 31 from supplying oil to the rotary motor 11 and controlling the construction machinery to stop its rotary motion. The second rotary control valve 42 has a second initial state, a second working state, and a combined state. When the second rotary control valve 42 is in the second initial state, the second variable pump 32 is only connected to the hydraulic system of the working equipment, allowing it to supply oil to the hydraulic system of the working equipment. In this case, both the hydraulic pump 2 and the second variable pump 32 supply oil to the hydraulic system of the working equipment simultaneously. When the second rotary control valve 42 is in the second operating state, the second variable pump 32 is only connected to the rotary motor 11, and oil can be supplied to the rotary motor 11 through the second variable pump 32. At this time, the first variable pump 31 and the second variable pump 32 simultaneously supply oil to the rotary motor 11. When the second rotary control valve 42 is in the combined state, the second variable pump 32 is simultaneously connected to the rotary motor 11 and the hydraulic system of the working equipment, and oil can be supplied to both the rotary motor 11 and the hydraulic system of the working equipment through the second variable pump 32.

[0068] Continue to refer to Figure 3 The rotary motor 11 has a first inlet and a second inlet. When oil enters through the first inlet and flows out through the second inlet, the rotary motor 11 moves in the forward direction; when oil enters through the second inlet and flows out through the first inlet, the rotary motor 11 moves in the reverse direction. It can be understood that the rotary motor 11 can move in two opposite directions, thereby enabling the engineering machinery to rotate in two directions.

[0069] The first working state of the first rotary control valve 41 includes a first forward working state and a first reverse working state. When the first rotary control valve 41 is in the first forward working state, the first rotary control valve 41 is used to connect the first variable pump 31 to the first liquid inlet and the second liquid inlet to the oil tank 5. At this time, after the oil enters the first rotary control valve 41, it is output to the first liquid inlet. After passing through the rotary motor 11, the oil flows out from the second liquid inlet. In addition, the first rotary control valve 41 connects the second liquid inlet to the oil tank 5 so that the oil flowing out through the second liquid inlet returns to the oil tank 5. When the first rotary control valve 41 is in the first reverse working state, the first rotary control valve 41 is used to connect the first variable pump 31 to the second liquid inlet, and the first liquid inlet is connected to the oil tank 5. At this time, after the oil enters the first rotary control valve 41, it is output to the second liquid inlet. After passing through the rotary motor 11, the oil flows out from the first liquid inlet. In addition, the first liquid inlet and the oil tank 5 are connected through the first rotary control valve 41 so that the oil flowing out of the first liquid inlet returns to the oil tank 5.

[0070] The second working state of the second rotary control valve 42 includes a second forward working state and a second reverse working state. When the second rotary control valve 42 is in the second forward working state, the second rotary control valve 42 is used to connect the second variable pump 32 to the first liquid inlet, and the second liquid inlet is connected to the oil tank 5. At this time, after the oil enters the second rotary control valve 42, it is output to the first liquid inlet. After passing through the rotary motor 11, the oil flows out from the second liquid inlet. In addition, the second liquid inlet and the oil tank 5 are connected through the second rotary control valve 42 so that the oil flowing out through the second liquid inlet returns to the oil tank 5. When the second rotary control valve 42 is in the second reverse working state, the second rotary control valve 42 is used to connect the second variable pump 32 to the second liquid inlet, and the first liquid inlet is connected to the oil tank 5. At this time, after the oil enters the second rotary control valve 42, it is output to the second liquid inlet. After passing through the rotary motor 11, the oil flows out from the first liquid inlet. In addition, the first liquid inlet and the oil tank 5 are connected through the second rotary control valve 42 so that the oil flowing out of the first liquid inlet returns to the oil tank 5.

[0071] The second rotary control valve 42 has two combined states: a forward combined state and a reverse combined state. When the second rotary control valve 42 is in the forward combined state, it connects the second variable pump 32 to both the first inlet and the hydraulic system of the working equipment, so that the oil tank 5 simultaneously supplies oil to both the rotary motor 11 and the hydraulic system of the working equipment, and the rotary motor 11 moves in the forward direction. When the second rotary control valve 42 is in the reverse combined state, it connects the second variable pump 32 to both the second inlet and the hydraulic system of the working equipment, so that the oil tank 5 simultaneously supplies oil to both the rotary motor 11 and the hydraulic system of the working equipment, and the rotary motor 11 moves in the reverse direction.

[0072] Reference Figures 3-5 The hydraulic system of the construction machinery also includes a pilot valve control pump 6, a first pilot valve group 61, and a second pilot valve group 62. The input end of the pilot valve control pump 6 is connected to the oil tank 5. The first pilot valve group 61 and the second pilot valve group 62 are both connected to the output end of the pilot valve control pump 6. The first pilot valve group 61 is used to change the state of the first rotary control valve 41, and the second pilot valve group 62 is used to change the state of the second rotary control valve 42.

[0073] like Figure 4 As shown, the first pilot valve group 61 includes a first pilot solenoid valve 611 and a second pilot solenoid valve 612. The first rotary control valve 41 is a solenoid valve and has left, center, and right positions. When the first rotary control valve 41 is in the right position, it is in a first forward rotation state; when it is in the center position, it is in a first initial state; and when it is in the left position, it is in a first reverse rotation state. The first pilot solenoid valve 611 and the second pilot solenoid valve 612 cooperate to change the valve core position of the first rotary control valve 41, thereby changing the state of the first rotary control valve 41. The first pilot solenoid valve 611 and the second pilot solenoid valve 612 can be controlled by the electronic control unit 81.

[0074] like Figure 5 As shown, the second pilot valve group 62 includes a third pilot solenoid valve 621 and a fourth pilot solenoid valve 622. The second rotary control valve 42 is also a solenoid valve and has a left position, a first combined position, a middle position, a second combined position, and a right position. When the second rotary control valve 42 is in the right position, the second rotary control valve 42 is in the second forward rotation working state; when the second rotary control valve 42 is in the second combined position, the second rotary control valve 42 is in the forward combined state; when the second rotary control valve 42 is in the middle position, the second rotary control valve 42 is in the second initial state; when the second rotary control valve 42 is in the first combined position, the second rotary control valve 42 is in the reverse combined state; when the second rotary control valve 42 is in the left position, the second rotary control valve 42 is in the second reverse rotation working state. The third pilot solenoid valve 621 and the fourth pilot solenoid valve 622 cooperate with each other to change the valve core position of the second rotary control valve 42, thereby changing the state of the second rotary control valve 42. The third pilot solenoid valve 621 and the fourth pilot solenoid valve 622 can also be controlled by the electronic control unit 81.

[0075] Furthermore, in this embodiment, the second rotary control valve 42 is a spool valve. During the adjustment process of the second rotary control valve 42 from the left position to the middle position, the second rotary control valve 42 is located in the first combined position. During the adjustment process of the second rotary control valve 42 from the middle position to the right position, the second rotary control valve 42 is located in the second combined position. In this way, oil can be supplied to the rotary motor 11 and the working hydraulic system at the same time, and flow control distribution can be realized, thereby achieving coordination and efficiency of rotary and other actions.

[0076] Optionally, the electronic control unit 81 is connected to an electronic control handle 82, and the electronic control unit 81 is also connected to the variable pump assembly 3. The driver can issue control commands to the electronic control unit 81 through the electronic control handle 82, so that the electronic control unit 81 can open or close each variable pump in the variable pump assembly 3 and control the power of each variable pump in the variable pump assembly 3. In addition, the electronic control unit 81 can also control the first pilot solenoid valve 611 and the second pilot solenoid valve 612 to indirectly change the valve core position of the first rotary control valve 41, thereby changing the state of the first rotary control valve 41. The electronic control unit 81 can also control the third pilot solenoid valve 621 and the fourth pilot solenoid valve 622 to indirectly change the valve core position of the second rotary control valve 42, thereby changing the state of the second rotary control valve 42.

[0077] Continue to refer to Figure 3 Multiple first variable pumps 31 are provided, and multiple first variable pumps 31 are simultaneously connected to a first rotary control valve 41; and / or multiple second variable pumps 32 are provided, and multiple second variable pumps 32 are simultaneously connected to a second rotary control valve 42. This embodiment exemplarily provides a scheme in which multiple first variable pumps 31 and multiple second variable pumps 32 are provided. By providing multiple first variable pumps 31, the flow rate and pressure of the oil entering the rotary motor 11 can be increased to meet the oil flow rate and pressure requirements of the rotary motor 11. By providing multiple second variable pumps 32, some second variable pumps 32 can provide power to the rotary motor 11 and others can provide power to the working equipment, thereby providing power for the movement of the boom, stick, and bucket of the construction machinery and the movement of the vehicle, thus enabling more precise distribution of hydraulic pressure.

[0078] Continue to refer to Figure 3A first check valve 71 is provided between the output end of the first variable pump 31 and the first rotary control valve 41. The first check valve 71 is configured to allow oil to be delivered from the output end of the first variable pump 31 to the first rotary control valve 41 only; and / or, a second check valve 72 is provided between the output end of the second variable pump 32 and the second rotary control valve 42. The second check valve 72 is configured to allow oil to be delivered from the output end of the second variable pump 32 to the second rotary control valve 42 only. This embodiment exemplarily provides a scheme that simultaneously provides the first check valve 71 and the second check valve 72, which can prevent oil from flowing back to the first variable pump 31 via the first rotary control valve 41 and to the second variable pump 32 via the second rotary control valve 42.

[0079] Example 2

[0080] This embodiment provides a hydraulic system control method, implemented using the hydraulic system of engineering machinery in Embodiment 1, with reference to... Figures 5-7 The hydraulic system control method includes the following steps.

[0081] S100: Determine whether the construction machinery has a slewing motion requirement and any working motion requirement. Working motion requirements include boom requirements, bucket requirements, stick requirements, and travel requirements.

[0082] Whether the construction machinery needs to perform a slewing motion or a working motion can be determined by whether the driver operates the corresponding button on the electronic control handle 82. For example, if the electronic control handle 82 is equipped with a slewing button, the driver will send a command to the electronic control unit 81 and generate a slewing motion requirement after pressing the slewing button.

[0083] In step S100, if the construction machinery has a slewing motion requirement and any working motion requirement, then step S200 is executed; if the construction machinery has a slewing motion requirement but no working motion requirement, then step S300 is executed; if the construction machinery has no slewing motion requirement but has any working motion requirement, then step S400 is executed; if the construction machinery has no slewing motion requirement and no working motion requirement, then step S500 is executed.

[0084] S200: Open the first variable pump 31 and the second variable pump 32, control the first rotary control valve 41 to enter the first working state, and control the second rotary control valve 42 to enter the combined state.

[0085] If the construction machinery requires a slewing motion and any other working motion, it indicates that the slewing motor 11 and the working equipment need to operate simultaneously. Therefore, the first slewing control valve 41 is controlled to enter the first working state, and the second slewing control valve 42 is controlled to enter the combined state, so that the second variable pump 32 can simultaneously supply oil to the hydraulic systems of the slewing motor 11 and the working equipment.

[0086] The electronic control unit 81 indirectly controls the states of the first rotary control valve 41 and the second rotary control valve 42 by controlling the pilot valve control pump 6, the first pilot valve group 61, and the second pilot valve group 62. Specifically, the electronic control unit 81 controls the first pilot solenoid valve 611 and the second pilot solenoid valve 612 to indirectly change the valve core position of the first rotary control valve 41, and the electronic control unit 81 controls the third pilot solenoid valve 621 and the fourth pilot solenoid valve 622 to indirectly change the valve core position of the second rotary control valve 42.

[0087] S300: Obtain the target rotation speed and determine the magnitude of the target rotation speed compared to the speed threshold.

[0088] If the construction machinery requires a slewing motion but has no other working motion required, then the machinery only needs to perform the slewing motion. The operator presses the high-speed slewing button or the low-speed slewing button on the electronic control handle 82. At this time, the electronic control handle 82 sends a corresponding signal to the electronic control unit 81, which automatically reads the preset target slewing speed.

[0089] In step S300, if the target rotational speed is not less than the speed threshold, it indicates that the target rotational speed is high. In this case, both the first variable pump 31 and the second variable pump 32 need to be opened simultaneously. The first rotational control valve 41 is controlled to enter the first working state, and the second rotational control valve 42 is controlled to enter the second working state, so that both the first variable pump 31 and the second variable pump 32 simultaneously provide power to the rotational motor 11. If the target rotational speed is less than the speed threshold, it indicates that the target rotational speed is low. In this case, the first variable pump 31 is opened and the second variable pump 32 is closed. The first rotational control valve 41 is controlled to enter the first working state, and power is provided to the rotational motor 11 only through the first variable pump 31.

[0090] S400: Close the first variable pump 31, open the second variable pump 32, and control the second rotary control valve 42 to enter the second initial state.

[0091] If the construction machinery does not require slewing but has any working action requirement, it means that the construction machinery does not need to slew at this time. Therefore, the first variable pump 31 is turned off and the second variable pump 32 is turned on. The second variable pump 32 provides power for the movement of the boom, stick, and bucket of the construction machinery, as well as the movement of the vehicle.

[0092] In some embodiments, the first variable pump 31 can be controlled to start at low power, and the first rotary control valve 41 can be controlled to enter the first initial state so that the entire oil circuit returns oil at a small flow rate.

[0093] S500: Close the first variable pump 31 and the second variable pump 32, control the first rotary control valve 41 to enter the first initial state, and control the second rotary control valve 42 to enter the second initial state.

[0094] If the construction machinery does not require rotation or any working action, then there is no need to turn on any of the variable pumps in variable pump group 3.

[0095] Example 3

[0096] This embodiment provides construction machinery, including the construction machinery hydraulic system of Embodiment 1, a chassis, a body movably mounted on the chassis, and working equipment mounted on the body. A slewing motor 11 drives the body to rotate relative to the chassis to complete the slewing. Furthermore, the construction machinery also includes a working equipment hydraulic system, with a hydraulic pump 2 connected to the working equipment hydraulic system to provide power to the working equipment. In this construction machinery hydraulic system, the slewing motor 11 is no longer powered by a hydraulic pump, but instead by a first variable pump 31 and a second variable pump 32. The first variable pump 31 can only power the slewing motor 11 to ensure sufficient power. The second variable pump 32 can power the slewing motor 11, the working equipment, or both simultaneously, depending on the actual situation. This balances the pressure required for slewing and other actions, avoiding large pressure differences between slewing and boom operations, which could lead to significant pressure loss, and preventing the boom speed from being affected by the slewing action dominating flow distribution during combined actions.

[0097] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art will be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A hydraulic system for construction machinery, comprising an oil tank (5), a hydraulic pump (2), and a rotary motor (11), wherein the oil tank (5) is connected to the hydraulic pump (2), and the hydraulic pump (2) is used to connect to the hydraulic system of the working equipment; Its features are, The hydraulic system of the engineering machinery also includes: The variable pump assembly (3) includes a first variable pump (31) and a second variable pump (32), both of which are connected to the oil tank (5). The rotary control valve assembly (4) includes a first rotary control valve (41) and a second rotary control valve (42). The first rotary control valve (41) is used to connect or disconnect the first variable pump (31) from the rotary motor (11). The second rotary control valve (42) is used to connect the second variable pump (32) only to the rotary motor (11), or only to the hydraulic system of the working equipment, or simultaneously to the rotary motor (11) and the hydraulic system of the working equipment.

2. The hydraulic system for engineering machinery according to claim 1, characterized in that, The first rotary control valve (41) has a first initial state and a first working state. When the first rotary control valve (41) is in the first working state, the first rotary control valve (41) is used to connect the first variable pump (31) to the rotary motor (11). When the first rotary control valve (41) is in the first initial state, the first rotary control valve (41) is used to disconnect the first variable pump (31) from the rotary motor (11). The second rotary control valve (42) has a second initial state, a second working state, and a combined state. When the second rotary control valve (42) is in the second initial state, the second variable pump (32) is only connected to the hydraulic system of the working equipment. When the second rotary control valve (42) is in the second working state, the second variable pump (32) is only connected to the rotary motor (11). When the second rotary control valve (42) is in the combined state, the second variable pump (32) is connected to both the rotary motor (11) and the hydraulic system of the working equipment.

3. The hydraulic system for engineering machinery according to claim 2, characterized in that, The rotary motor (11) has a first inlet and a second inlet. When the oil enters through the first inlet and flows out through the second inlet, the rotary motor (11) moves in the forward direction. When the oil enters through the second inlet and flows out through the first inlet, the rotary motor (11) moves in the reverse direction. The first working state of the first rotary control valve (41) includes a first forward working state and a first reverse working state. When the first rotary control valve (41) is in the first forward working state, the first rotary control valve (41) is used to connect the first variable pump (31) to the first liquid inlet and the second liquid inlet to the oil tank (5). When the first rotary control valve (41) is in the first reverse working state, the first rotary control valve (41) is used to connect the first variable pump (31) to the second liquid inlet and the first liquid inlet to the oil tank (5). The second working state of the second rotary control valve (42) includes a second forward working state and a second reverse working state. When the second rotary control valve (42) is in the second forward working state, the second rotary control valve (42) is used to connect the second variable pump (32) to the first liquid inlet, and the second liquid inlet is connected to the oil tank (5). When the second rotary control valve (42) is in the second reverse working state, the second rotary control valve (42) is used to connect the second variable pump (32) to the second liquid inlet, and the first liquid inlet is connected to the oil tank (5). The second rotary control valve (42) has two combined states: a forward combined state and a reverse combined state. When the second rotary control valve (42) is in the forward combined state, it is used to connect the second variable pump (32) to the first inlet and the hydraulic system of the working equipment simultaneously. When the second rotary control valve (42) is in the reverse combined state, it is used to connect the second variable pump (32) to the second inlet and the hydraulic system of the working equipment simultaneously.

4. The hydraulic system for engineering machinery according to claim 2, characterized in that, It also includes a pilot valve control pump (6), a first pilot valve group (61), and a second pilot valve group (62). The input end of the pilot valve control pump (6) is connected to the oil tank (5). The first pilot valve group (61) and the second pilot valve group (62) are both connected to the output end of the pilot valve control pump (6). The first pilot valve group (61) is used to change the state of the first rotary control valve (41), and the second pilot valve group (62) is used to change the state of the second rotary control valve (42).

5. The hydraulic system for engineering machinery according to any one of claims 1-4, characterized in that, Multiple first variable pumps (31) are provided, and multiple first variable pumps (31) are simultaneously connected to the first rotary control valve (41); and / or, Multiple second variable pumps (32) are provided, and multiple second variable pumps (32) are simultaneously connected to the second rotary control valve (42).

6. The hydraulic system for engineering machinery according to any one of claims 1-4, characterized in that, A first check valve (71) is provided between the output end of the first variable pump (31) and the first rotary control valve (41). The first check valve (71) is configured to allow oil to be delivered only from the output end of the first variable pump (31) to the first rotary control valve (41); and / or, A second check valve (72) is provided between the output end of the second variable pump (32) and the second rotary control valve (42). The second check valve (72) is configured to allow oil to be delivered from the output end of the second variable pump (32) to the second rotary control valve (42).

7. A hydraulic system control method, characterized in that, In the engineering machinery hydraulic system as described in any one of claims 1-6, the first rotary control valve (41) has a first initial state and a first working state. When the first rotary control valve (41) is in the first working state, the first rotary control valve (41) is used to connect the first variable pump (31) to the rotary motor (11). When the first rotary control valve (41) is in the first initial state, the first rotary control valve (41) is used to disconnect the first variable pump (31) from the rotary motor (11). The second rotary control valve (42) has a second initial state, a second working state, and a combined state. When the second rotary control valve (42) is in the second initial state, the second variable pump (32) is only connected to the hydraulic system of the working equipment. When the second rotary control valve (42) is in the second working state, the second variable pump (32) is only connected to the rotary motor (11). When the second rotary control valve (42) is in the combined state, the second variable pump (32) is simultaneously connected to both the rotary motor (11) and the hydraulic system of the working equipment. The hydraulic system control method includes: S100: Determine whether the construction machinery has a slewing motion requirement and any working motion requirement, the working motion requirement including boom requirement, bucket requirement, stick requirement and travel requirement; If the construction machinery requires a slewing motion or any working motion, then proceed to step S200. S200: Open the first variable pump (31) and the second variable pump (32), control the first rotary control valve (41) to enter the first working state, and control the second rotary control valve (42) to enter the compound state.

8. The hydraulic system control method according to claim 7, characterized in that, In step S100, if the construction machinery has a slewing motion requirement but no working motion requirement, then step S300 is executed. S300: Obtain the target rotation speed and determine the magnitude of the target rotation speed compared to the speed threshold; If the target rotation speed is not less than the speed threshold, then the first variable pump (31) and the second variable pump (32) are turned on, the first rotation control valve (41) is controlled to enter the first working state, and the second rotation control valve (42) is controlled to enter the second working state. If the target rotation speed is less than the speed threshold, the first variable pump (31) is turned on and the second variable pump (32) is turned off, and the first rotation control valve (41) is controlled to enter the first working state.

9. The hydraulic system control method according to claim 7, characterized in that, In step S100, if the construction machinery does not require a slewing motion but has any working motion requirement, then step S400 is executed. S400: Close the first variable pump (31), open the second variable pump (32), and control the second rotary control valve (42) to enter the second initial state.

10. Construction machinery, characterized in that, The hydraulic system for construction machinery as described in any one of claims 1-6 further includes a chassis, a body movably mounted on the chassis, and working equipment mounted on the body, wherein the rotary motor (11) is used to drive the body to rotate relative to the chassis.

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