A hydraulic control system for a loader

Abstract

The present invention belongs to the technical field of loaders and discloses a hydraulic control system for a loader. The control system includes a fuel tank, a working pump, a steering pump, a working valve group, an accumulator, an unloading valve group, a first control valve group, a second control valve group, and a third control valve group. The working valve group includes a boom reversing valve and a bucket reversing valve. The working valve group has an oil port P0 connecting the boom reversing valve and the bucket reversing valve. The working pump is connected to the oil port P0. The unloading valve group is used to unload the working pump. The accumulator can be connected and disconnected with the hydraulic control terminals e1 and e2 of the boom reversing valve and the hydraulic control terminals e3 and e4 of the bucket reversing valve via the first control valve group. The accumulator can be connected and disconnected with the unloading valve group via the second control valve group. The accumulator can open the unloading valve group. The steering pump can be connected and disconnected with the oil port P0 via the third control valve group. This system can realize on-demand operation of the working pump and steering pump, achieve sequential system power distribution, have a high degree of electronic control, and are more energy-efficient.

Description

Technical Field

[0001] The present invention relates to the technical field of loaders, and in particular to a hydraulic control system for a loader. Background Art

[0002] Currently, a single-variable hydraulic system for a loader is provided with a working pump and a steering pump. Specifically, the working pump is a gear pump and the steering pump is a plunger pump, which generally uses a load-sensing control and a pressure-compensated control method.

[0003] Existing hydraulic control systems for loaders typically operate in two modes: The steering pump merges with the working pump when the boom reversing valve and / or bucket steering valve are actuated, and the steering pump supplies oil only to the steering system when the boom reversing valve and / or bucket steering valve are inactive. However, in practice, various requirements may arise. For example, when the boom is lowered, neither the working pump nor the steering pump requires oil supply. When the bucket is retracted or tipped, only the steering pump supplies oil to the working system, unloading the working pump. Current systems cannot achieve this on-demand distribution. Summary of the Invention

[0004] The object of the present invention is to provide a loader hydraulic control system that can realize the on-demand operation of the working pump and the steering pump, realize the sequential distribution of the power of the entire hydraulic system, have a high degree of system electronic control, and are more energy-efficient.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] A loader hydraulic control system includes a fuel tank, a working pump, a steering pump, a working valve group, an accumulator, an unloading valve group, a first control valve group, a second control valve group and a third control valve group; wherein,

[0007] The oil inlets of the working pump and the steering pump are connected to the oil tank;

[0008] The working valve group includes a boom reversing valve and a bucket reversing valve. The boom reversing valve has a hydraulic control end e1 and a hydraulic control end e2, and the bucket reversing valve has a hydraulic control end e3 and a hydraulic control end e4. The working valve group has an oil port P0, and the oil port P0 is connected to the oil inlet of the boom reversing valve and the bucket reversing valve;

[0009] The working pump is connected to the oil port P0, and the unloading valve group is provided on the connecting pipeline between the oil outlet of the working pump and the oil port P0, and the unloading valve group is used to unload the working pump;

[0010] The accumulator can be connected to or disconnected from the hydraulic control end e1, the hydraulic control end e2, the hydraulic control end e3, and the hydraulic control end e4 respectively through the first control valve group;

[0011] The accumulator can be connected to or disconnected from the unloading valve group through the second control valve group, and the unloading valve group can be opened when the accumulator is connected to the unloading valve group;

[0012] The steering pump can be connected to or disconnected from the oil port P0 through the third control valve group.

[0013] Preferably, the unloading valve group includes an unloading reversing valve and a relief valve, the oil outlet of the working pump is connected to the oil inlet of the unloading reversing valve and the oil inlet of the relief valve, the oil outlet of the unloading reversing valve is connected to the oil tank, and the oil outlet of the relief valve is connected to the hydraulic control end e5 of the unloading reversing valve and the oil tank;

[0014] The accumulator can be connected to or disconnected from the oil outlet of the unloading reversing valve through the second control valve group.

[0015] Preferably, the unloading valve group further includes a first one-way valve, which is configured to conduct hydraulic oil in a unidirectional direction from the oil inlet of the unloading reversing valve to the oil inlet of the relief valve.

[0016] Preferably, the first control valve group includes a first hydraulic-controlled-end reversing valve, a second hydraulic-controlled-end reversing valve, a third hydraulic-controlled-end reversing valve and a fourth hydraulic-controlled-end reversing valve, and the oil port P0 is connected to the oil inlets of the first hydraulic-controlled-end reversing valve, the second hydraulic-controlled-end reversing valve, the third hydraulic-controlled-end reversing valve and the fourth hydraulic-controlled-end reversing valve, respectively; the oil outlet of the first hydraulic-controlled-end reversing valve is connected to the hydraulic-controlled end e1, the oil outlet of the second hydraulic-controlled-end reversing valve is connected to the hydraulic-controlled end e2, the oil outlet of the third hydraulic-controlled-end reversing valve is connected to the hydraulic-controlled end e3, and the oil outlet of the fourth hydraulic-controlled-end reversing valve is connected to the hydraulic-controlled end e4.

[0017] Preferably, the first hydraulic-controlled-end reversing valve, the second hydraulic-controlled-end reversing valve, the third hydraulic-controlled-end reversing valve and the fourth hydraulic-controlled-end reversing valve are all configured as electromagnetic reversing valves.

[0018] Preferably, the second control valve group includes a first control reversing valve and a second control reversing valve, and the third control valve group includes a third control reversing valve; wherein,

[0019] The accumulator is connected to the oil inlet of the first control reversing valve and the oil inlet of the second control reversing valve, the oil outlet of the first control reversing valve is connected to the hydraulic control end e6 of the third control reversing valve, the oil outlet of the second control reversing valve is connected to the unloading valve group, the oil outlet of the steering pump is connected to the oil inlet of the third control reversing valve, and the oil outlet of the third control reversing valve is connected to the oil port P0.

[0020] Preferably, the invention further comprises a steering gear and a flow amplification valve, wherein the steering pump is configured as a plunger pump, the oil outlet of the steering pump is connected to the steering gear and the flow amplification valve, the steering gear has a first feedback oil port, and the flow amplification valve has a second feedback oil port;

[0021] The third control valve group also includes a shuttle valve, the working oil port B1 of the shuttle valve is connected to the oil outlet of the third control reversing valve, the working oil port B2 of the shuttle valve is connected to the first feedback oil port and the second feedback oil port, and the working oil port B3 of the shuttle valve is connected to the third feedback oil port of the steering pump, and the displacement of the steering pump is adjusted according to the oil amount in the third feedback oil port.

[0022] Preferably, a second one-way valve is provided between the working oil port B3 of the shuttle valve and the third feedback oil port, and the second one-way valve is configured to conduct hydraulic oil in a unidirectional direction from the working oil port B3 to the third feedback oil port.

[0023] Preferably, the first control reversing valve and the second control reversing valve are both configured as electromagnetic reversing valves.

[0024] Preferably, a pressure reducing valve is further included, the accumulator is connected to the oil inlet of the pressure reducing valve, and the oil outlet of the pressure reducing valve is connected to the oil port P0.

[0025] Beneficial effects:

[0026] The loader hydraulic control system provided by the present invention, through the coordinated control of the unloading valve group, the first control valve group, the second control valve group, and the third control valve group, can achieve on-demand operation of the working pump and the steering pump. The first control valve group controls the switching action of the boom reversing valve and the bucket reversing valve, thereby achieving corresponding control of the loader's lifting and the bucket's retraction. The unloading valve group controls whether the working pump is unloaded; the second control valve group controls whether the accumulator's pilot oil controls the opening of the unloading valve group; and the third control valve group controls whether the steering pump is connected to oil port P0, that is, whether the steering pump and the working pump merge. The working pump and steering pump operate on demand, thereby achieving sequential distribution of power for the entire hydraulic system, a high degree of system electronic control, and a more energy-efficient system. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of a loader hydraulic control system provided by the present invention;

[0028] Figure 2 It is a schematic diagram of the unloading valve group provided by the present invention;

[0029] Figure 3 It is a schematic diagram of the working valve group and the first control valve group provided by the present invention;

[0030] Figure 4 It is a schematic diagram of the second control valve group and the third control valve group provided by the present invention.

[0031] In the picture:

[0032] 1. Fuel tank;

[0033] 21. Working pump; 22. Steering pump;

[0034] 31. Boom reversing valve; 32. Bucket reversing valve; 33. Boom cylinder; 34. Bucket cylinder;

[0035] 4. Accumulator;

[0036] 51. Unloading reversing valve; 52. Overflow valve; 53. First check valve;

[0037] 61. First hydraulic-controlled reversing valve; 62. Second hydraulic-controlled reversing valve; 63. Third hydraulic-controlled reversing valve; 64. Fourth hydraulic-controlled reversing valve;

[0038] 71. First control reversing valve; 72. Second control reversing valve;

[0039] 81. Third control reversing valve; 82. Shuttle valve; 83. Second check valve;

[0040] 9. Steering gear;

[0041] 10. Flow amplification valve;

[0042] 11. Pressure reducing valve;

[0043] 12. Braking system;

[0044] 13. Controller; 131. Electric control handle. DETAILED DESCRIPTION

[0045] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0046] In the description of the present invention, unless otherwise expressly specified or limited, the terms "connected," "connected," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention in specific circumstances.

[0047] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly below or obliquely below the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0048] In the description of this embodiment, the terms "upper," "lower," "right," and other orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely for ease of description and simplified operation. They do not indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first" and "second" are used solely for descriptive purposes and have no special meanings.

[0049] This embodiment provides a loader hydraulic control system. Figures 1 to 4 As shown, the loader hydraulic control system includes a fuel tank 1, a working pump 21, a steering pump 22, a working valve group, an accumulator 4, an unloading valve group, a first control valve group, a second control valve group, and a third control valve group. Among them, the oil inlets of the working pump 21 and the steering pump 22 are connected to the fuel tank 1; the working valve group includes a boom reversing valve 31 and a bucket reversing valve 32. The boom reversing valve 31 has a hydraulic control end e1 and a hydraulic control end e2, and the bucket reversing valve 32 has a hydraulic control end e3 and a hydraulic control end e4. The working valve group has an oil port P0, which is connected to the oil inlet of the boom reversing valve 31 and the bucket reversing valve 32; the working pump 21 is connected to the oil port P0, and the unloading valve group is provided between the oil outlet of the working pump 21 and the oil outlet of the bucket reversing valve 32. On the connecting pipeline between the oil port P0, the unloading valve group is used to unload the working pump 21; the accumulator 4 can be connected to or disconnected from the hydraulic control end e1, hydraulic control end e2, hydraulic control end e3 and hydraulic control end e4 respectively through the first control valve group; the accumulator 4 can be connected to or disconnected from the unloading valve group through the second control valve group, and the unloading valve group can be opened when the accumulator 4 is connected to the unloading valve group; the steering pump 22 can be connected to or disconnected from the oil port P0 through the third control valve group.

[0050] Specifically, the two working oil ports of the boom reversing valve 31 are connected to the boom cylinder 33, and the return oil port of the boom reversing valve 31 is connected to the oil tank 1. The boom cylinder 33 is connected to the boom of the loader. The boom reversing valve 31 has a neutral position, a lifting position, a lowering position and a floating position. When the lifting position of the boom reversing valve 31 is in the working position, the hydraulic oil can drive the cylinder rod of the boom cylinder 33 to extend through the boom reversing valve 31, thereby achieving the lifting of the boom; when the lowering position of the boom reversing valve 31 is in the working position, the hydraulic oil can drive the cylinder rod of the boom cylinder 33 to retract through the boom reversing valve 31, thereby achieving the lowering of the boom; when the floating position of the boom reversing valve 31 is in the working position, the boom cylinder 33 remains in a floating state, that is, the boom is floating.

[0051] Specifically, the two working oil ports of the bucket reversing valve 32 are connected to the bucket cylinder 34, and the return oil port of the bucket reversing valve 32 is connected to the oil tank 1. The bucket cylinder 34 is connected to the bucket of the loader. The bucket reversing valve 32 has a neutral position, a dumping position, and a retracted position. When the retracted position of the bucket reversing valve 32 is in the working position, hydraulic oil can drive the cylinder rod of the bucket cylinder 34 to extend through the bucket reversing valve 32, thereby achieving the retraction of the bucket; when the dumping position of the bucket reversing valve 32 is in the working position, hydraulic oil can drive the cylinder rod of the bucket cylinder 34 to retract through the bucket reversing valve 32, thereby achieving the tipping and unloading of the bucket.

[0052] Specifically, the accumulator 4 is a brake accumulator 4 connected to the loader's brake system 12. Accumulator 4 can store hydraulic fluid in the brake system 12 for use as pilot fluid in the hydraulic control system. Accumulator 4 can be connected or disconnected with hydraulic terminals e1, e2, e3, and e4 via a first control valve group. For example, the first control valve group connects accumulator 4 to hydraulic terminal e1, allowing hydraulic fluid from accumulator 4 to be delivered to hydraulic terminal e1, shifting the lift control valve spool to the left, to the lifting position, and into the working position. The first control valve group connects accumulator 4 to hydraulic terminal e2, allowing hydraulic fluid from accumulator 4 to be delivered to hydraulic terminal e2, shifting the lift control valve spool to the right, to the lowering position, and into the working position. Furthermore, hydraulic fluid from accumulator 4 can be further delivered to hydraulic terminal e2, shifting the lift control valve spool to the right, to the floating position, and into the working position. The first control valve group controls accumulator 4 to connect to hydraulic control terminal e3. The hydraulic oil output from accumulator 4 can be delivered to hydraulic control terminal e3, causing the spool of the bucket control valve to move leftward to the bucket-retracting position, which is the working position. The first control valve group controls accumulator 4 to connect to hydraulic control terminal e4. The hydraulic oil output from accumulator 4 can be delivered to hydraulic control terminal e4, causing the spool of the bucket control valve to move rightward to the bucket-dumping position, which is the working position.

[0053] In this embodiment, the loader's hydraulic control system also includes a pressure-reducing valve 11. The accumulator 4 is connected to the oil inlet of the pressure-reducing valve 11. The oil outlet of the pressure-reducing valve 11 is connected or disconnected to the hydraulic control terminals e1, e2, e3, and e4 via the first control valve group. The pressure-reducing valve 11 reduces the high-pressure oil in the accumulator 4 to a certain pressure before it is delivered as pilot oil.

[0054] In this embodiment, the unloading valve group includes an unloading reversing valve 51 and a relief valve 52. The oil outlet of the working pump 21 is connected to the oil inlet of the unloading reversing valve 51 and the oil inlet of the relief valve 52. The oil outlet of the unloading reversing valve 51 is connected to the oil tank 1. The oil outlet of the relief valve 52 is connected to the hydraulic control end e5 of the unloading reversing valve 51 and the oil tank 1. Specifically, the working pump 21 pumps hydraulic oil from the oil tank 1. When the hydraulic oil pressure does not reach the unloading threshold, the unloading reversing valve 51 and the relief valve 52 are both in the closed state. At this time, the hydraulic oil is directly delivered to the working valve group through the oil port P0. When the hydraulic oil pressure reaches the unloading threshold, the hydraulic oil flows to the hydraulic control end of the relief valve 52, pushing the relief valve 52 to reverse and open, allowing the hydraulic oil to reach the hydraulic control end e5 of the unloading reversing valve 51, pushing the unloading reversing valve 51 to reverse and open, so that the hydraulic oil can flow back to the oil tank 1 through the unloading reversing valve 51, thereby unloading the working pump 21. In addition, the accumulator 4 can be connected or disconnected with the oil outlet of the unloading reversing valve 51 through the second control valve group. When the accumulator 4 is connected to the oil outlet of the unloading reversing valve 51 through the second control valve group, it can also unload the pilot oil.

[0055] In this embodiment, the unloading valve assembly further includes a first one-way valve 53, which is configured to unidirectionally direct hydraulic oil from the oil inlet of the unloading reversing valve 51 to the oil inlet of the relief valve 52. The provision of the first one-way valve 53 directs the oil path between the oil inlet of the unloading reversing valve 51 and the oil inlet of the relief valve 52, preventing the hydraulic oil output by the working pump 21 from flowing back toward the unloading reversing valve 51 and thus affecting the unloading pressure of the unloading reversing valve 51.

[0056] In this embodiment, the first control valve group includes a first hydraulic-end reversing valve 61, a second hydraulic-end reversing valve 62, a third hydraulic-end reversing valve 63 and a fourth hydraulic-end reversing valve 64. The oil port P0 is connected to the oil inlets of the first hydraulic-end reversing valve 61, the second hydraulic-end reversing valve 62, the third hydraulic-end reversing valve 63 and the fourth hydraulic-end reversing valve 64, respectively. The oil outlet of the first hydraulic-end reversing valve 61 is connected to the hydraulic-controlled end e1, the oil outlet of the second hydraulic-end reversing valve 62 is connected to the hydraulic-controlled end e2, the oil outlet of the third hydraulic-end reversing valve 63 is connected to the hydraulic-controlled end e3, and the oil outlet of the fourth hydraulic-end reversing valve 64 is connected to the hydraulic-controlled end e4. Specifically, when the first hydraulic-controlled end reversing valve 61 is turned on and the second hydraulic-controlled reversing valve is turned off, the hydraulic oil at the oil port P0 can reach the hydraulic-controlled end e1 of the boom reversing valve 31 through the first pressure-controlled reversing valve, thereby pushing the valve core of the boom reversing valve 31 to the left, so that the boom reversing valve 31 can be switched to the lifting position; when the first hydraulic-controlled end reversing valve 61 is turned off and the second hydraulic-controlled reversing valve is turned on, the hydraulic oil at the oil port P0 can reach the hydraulic-controlled end e2 of the boom reversing valve 31 through the second pressure-controlled reversing valve, thereby pushing the valve core of the boom reversing valve 31 to the right, so that the boom reversing valve 31 can be switched to the lowering position or the floating position. When the third hydraulic-controlled reversing valve 63 is turned on and the fourth hydraulic-controlled reversing valve is turned off, the hydraulic oil at the oil port P0 can reach the hydraulic-controlled end e3 of the bucket reversing valve 32 through the third pressure-controlled reversing valve, thereby pushing the valve core of the bucket reversing valve 32 to the left, so that the bucket reversing valve 32 can be switched to the bucket retracting position; when the third hydraulic-controlled reversing valve 63 is turned off and the fourth hydraulic-controlled reversing valve is turned on, the hydraulic oil at the oil port P0 can reach the hydraulic-controlled end e4 of the bucket reversing valve 32 through the fourth pressure-controlled reversing valve, thereby pushing the valve core of the bucket reversing valve 32 to the right, so that the bucket reversing valve 32 can be switched to the bucket dumping position.

[0057] Exemplarily, the first hydraulic-controlled reversing valve 61, the second hydraulic-controlled reversing valve 62, the third hydraulic-controlled reversing valve 63, and the fourth hydraulic-controlled reversing valve 64 are all configured as solenoid reversing valves. Specifically, the loader hydraulic control system further includes a controller 13, the operating end of which is communicatively connected to an electric control handle 131. The controller 13 is communicatively connected to the first hydraulic-controlled reversing valve 61, the second hydraulic-controlled reversing valve 62, the third hydraulic-controlled reversing valve 63, and the fourth hydraulic-controlled reversing valve 64, respectively. Control instructions are issued by operating the electric control handle 131, and the controller 13 then energizes the electromagnets corresponding to the first hydraulic-controlled reversing valve 61, the second hydraulic-controlled reversing valve 62, the third hydraulic-controlled reversing valve 63, and the fourth hydraulic-controlled reversing valve 64, thereby achieving rapid and reliable reversing control of the first hydraulic-controlled reversing valve 61, the second hydraulic-controlled reversing valve 62, the third hydraulic-controlled reversing valve 63, and the fourth hydraulic-controlled reversing valve 64.

[0058] In this embodiment, the second control valve group includes a first control reversing valve 71 and a second control reversing valve 72 , and the third control valve group includes a third control reversing valve 81 .

[0059] The accumulator 4 is connected to the oil inlet of the first control reversing valve 71 and the oil inlet of the second control reversing valve 72. The oil outlet of the first control reversing valve 71 is connected to the hydraulic control port e6 of the third control reversing valve 81. The oil outlet of the second control reversing valve 72 is connected to the unloading valve group. The oil outlet of the steering pump 22 is connected to the oil inlet of the third control reversing valve 81, and the oil outlet of the third control reversing valve 81 is connected to oil port P0. Specifically, the first control reversing valve 71 is configured to connect and disconnect the pilot oil to the second control valve group, namely, the third control reversing valve 81. Specifically, when the first control reversing valve 71 is open, pilot oil flows through the first control reversing valve 71 to the hydraulic control terminal e6 of the third control reversing valve 81, causing the third control reversing valve 81 to reverse direction, opening the oil path between the oil outlet of the steering pump 22 and oil port P0. This allows the steering pump 22 to pump hydraulic oil from the fuel tank 1 to oil port P0, thereby achieving merging of the steering pump 22 and the working pump 21. Specifically, the second control reversing valve 72 is configured to connect and disconnect the pilot oil with the unloading valve assembly. Specifically, the oil outlet of the second control reversing valve 72 is connected to the hydraulic control terminal e5 of the unloading reversing valve 51. When the second control reversing valve 72 is open, the hydraulic oil in the accumulator 4 can flow through the second control reversing valve 72 to the hydraulic control terminal e5 of the unloading reversing valve 51, forcing the unloading reversing valve 51 to reverse direction, thereby unloading the hydraulic oil in the working pump 21.

[0060] For example, the first control reversing valve 71 and the second control reversing valve 72 are both configured as solenoid reversing valves. Specifically, the controller 13 is in communication with the first control reversing valve 71 and the second control reversing valve 72. Control instructions are issued via an electric control handle 131, which then energizes the corresponding electromagnets of the first and second control reversing valves 71 and 72, thereby achieving fast and reliable switching control of the first and second control reversing valves 71 and 72.

[0061] In this embodiment, the loader hydraulic control system also includes a steering gear 9 and a flow amplification valve 10. The steering pump 22 is configured as a plunger pump. The oil outlet of the steering pump 22 is connected to the steering gear 9 and the flow amplification valve 10. The steering gear 9 has a first feedback port, and the flow amplification valve 10 has a second feedback port. The third control valve group also includes a shuttle valve 82. Its working port B1 is connected to the oil outlet of the third control reversing valve 81. Its working port B2 is connected to the first and second feedback ports. Its working port B3 is connected to the third feedback port of the steering pump 22. The displacement of the steering pump 22 is adjusted based on the oil level in the third feedback port. Specifically, the Ls signal from the flow amplification valve 10 and the Ls signal from the steering gear 9 are connected in series, collectively referred to as the steering system Ls signal. When the machine is in steering mode, the hydraulic oil in the steering gear 9 is fed back to the third feedback port of the steering pump 22 via the working ports B2 and B3 of the shuttle valve 82, controlling the pump's displacement. When the working valve group of the entire machine is operating, that is, when the boom is raised, lowered, the bucket is retracted, or dumped, the hydraulic oil delivered by the working pump 21 is fed back to the third feedback port of the steering pump 22 via the working oil ports B1 and B3 of the shuttle valve 82. At this time, the steering pump 22 operates at maximum displacement. The principle and process of adjusting the displacement of the plunger pump are prior art and are not the focus of this application, so they will not be detailed here.

[0062] In this embodiment, a second check valve 83 is installed between the working oil port B3 and the third feedback oil port of shuttle valve 82. This second check valve 83 is configured to unidirectionally direct hydraulic oil from the working oil port B3 to the third feedback oil port. The provision of this second check valve 83 prevents hydraulic oil from the third feedback oil port from flowing back into shuttle valve 82, ensuring the reliability and effectiveness of this unidirectional flow of hydraulic oil.

[0063] By way of example, the working conditions of the valve group and the oil circuit transmission conditions corresponding to several different working conditions of a loader using the hydraulic control system are described below.

[0064] After the entire machine is started, the boom and bucket remain inactive, meaning the working valve assembly is inoperative. The electronic control handle 131 remains inactive. The first, second, third, and fourth hydraulically controlled reversing valves 61, 62, 63, and 64 are all in neutral position, with no pilot oil entering. The valve cores of the boom reversing valve 31 and the bucket reversing valve 32 are all in neutral. The hydraulic oil pumped by the working pump 21 passes through the unloading reversing valve 51 and returns to the oil tank 1. Since there is no hydraulic oil at the hydraulic control end e6 of the third control reversing valve 81 at this time, the third control reversing valve 81 does not reverse direction, and there is no communication between the steering pump 22 and the oil port P0. Therefore, the steering pump 22 only adjusts its displacement based on the steering system Ls signal feedback to supply oil to the steering gear 9.

[0065] When the boom is lifted, the working pump 21 and the steering pump 22 need to merge to jointly supply oil to the boom reversing valve 31 of the working valve group. The electric control handle 131 communicates with the controller 13, and the controller 13 sends a current signal to the first hydraulic end reversing valve 61 and the first control reversing valve 71, so that the first hydraulic end reversing valve 61 and the first control reversing valve 71 are reversed. Specifically, the first hydraulic end reversing valve 61 switches the oil path from the oil port P0 to the hydraulic end e1 of the boom reversing valve 31. A pilot oil flow route is: accumulator 4, pressure reducing valve 11, first hydraulic end reversing valve 61, hydraulic end e1 of the boom reversing valve 31, pushing the boom reversing valve 31 to reverse, and the boom reversing valve 31 moves left to move the valve core to the lifting position. Another pilot oil flow path passes through the accumulator 4, the pressure reducing valve 11, the first control reversing valve 71, and the hydraulic control terminal e6 of the third control reversing valve 81. This drives the third control reversing valve 81 to reverse direction, thereby opening the oil path between the steering pump 22 and port P0. The hydraulic oil pumped by the working pump 21 flows through the working pump 21, port P0, the boom reversing valve 31, and the rodless cavity of the boom cylinder 33. The hydraulic oil pumped by the steering pump 22 flows through the steering pump 22, the third control reversing valve 81, port P0, the boom reversing valve 31, and the rodless cavity of the boom cylinder 33. The hydraulic oil from the steering pump 22 and the working pump 21 merge to push the rod of the boom cylinder 33 outward.

[0066] It is worth mentioning that if steering is required during lifting, the steering pump 22 will first ensure steering and then merge with the working pump 21.

[0067] It is worth mentioning that when the oil pressure at the oil port P0 reaches the unloading threshold, the hydraulic oil flows to the hydraulic control end of the overflow valve 52, pushing the overflow valve 52 to reverse and conduct, so that the hydraulic oil can reach the hydraulic control end e5 of the unloading reversing valve 51, pushing the unloading reversing valve 51 to reverse and conduct, so that the hydraulic oil can flow back to the oil tank 1 through the unloading reversing valve 51, and unload the working pump 21.

[0068] The above control is used in situations where dual pumps are required to supply oil to the working valve group, such as boom lifting, boom lifting and bucket retraction, and boom lifting and bucket unloading.

[0069] When the boom is lowered (not supporting the vehicle), neither the working pump 21 nor the steering pump 22 needs to supply oil to the working valve group. The rod chamber is replenished with oil through the return oil from the rodless chamber of the boom cylinder 33. The electric control handle 131 communicates with the controller 13, and the controller 13 sends a current signal to the second hydraulic end reversing valve 62 and the second control reversing valve 72, so that the second hydraulic end reversing valve 62 and the second control reversing valve 72 are reversed. Specifically, the second hydraulic end reversing valve 62 switches the oil path from the oil port P0 to the hydraulic end e2 of the boom reversing valve 31. A pilot oil flow route is: accumulator 4, pressure reducing valve 11, second hydraulic end reversing valve 62, hydraulic end e2 of the boom reversing valve 31, pushing the boom reversing valve 31 to reverse, and the boom reversing valve 31 moves to the right to move the valve core to the lowered position. Another pilot oil flow path passes through the accumulator 4, the pressure reducing valve 11, the second control reversing valve 72, and the hydraulic control terminal e5 of the unloading reversing valve 51, pushing the unloading reversing valve 51 to switch to a conductive state. The hydraulic oil pumped by the working pump 21 flows through the working pump 21, the unloading reversing valve 51, and the oil tank 1, achieving hydraulic oil unloading of the working pump 21. Since the hydraulic control terminal e6 of the third control reversing valve 81 is empty at this time, the third control reversing valve 81 does not switch, and there is no conduction between the steering pump 22 and the oil port P0. Therefore, the steering pump 22 only adjusts its displacement based on the steering system Ls signal feedback to supply oil to the steering gear 9.

[0070] When the bucket is retracted, the working pump 21 is unloaded, and the steering pump 22 supplies oil to the bucket reversing valve 32 of the working valve group. The electric control handle 131 communicates with the controller 13, and the controller 13 sends a current signal to the third hydraulic-controlled reversing valve 63, the first control reversing valve 71, and the second control reversing valve 72, causing the third hydraulic-controlled reversing valve 63, the first control reversing valve 71, and the second control reversing valve 72 to reverse. Specifically, the third hydraulic-controlled reversing valve 63 switches the oil path from the oil port P0 to the hydraulic-controlled end e3 of the bucket reversing valve 32. A pilot oil flow path passes through: the accumulator 4, the pressure reducing valve 11, the third hydraulic-controlled reversing valve 63, and the hydraulic-controlled end e3 of the bucket reversing valve 32, pushing the bucket reversing valve 32 to reverse. The bucket reversing valve 32 moves leftward, causing the valve core to move to the retracted position. Another pilot oil flow path passes through the accumulator 4, the pressure-reducing valve 11, the first control reversing valve 71, and the hydraulic control terminal e6 of the third control reversing valve 81, which drives the third control reversing valve 81 to open the oil path between the steering pump 22 and oil port P0. Yet another pilot oil flow path passes through the accumulator 4, the pressure-reducing valve 11, the second control reversing valve 72, and the hydraulic control terminal e5 of the unloading reversing valve 51, which drives the unloading reversing valve 51 to open the oil path. The hydraulic oil pumped by the working pump 21 flows through the working pump 21, the unloading reversing valve 51, and the oil tank 1, unloading the hydraulic oil from the working pump 21. The hydraulic oil pumped by the steering pump 22 flows through the steering pump 22, the third control reversing valve 81, oil port P0, the bucket reversing valve 32, and the rod chamber of the bucket cylinder 34, pushing the rod of the bucket cylinder 34 outward, achieving the bucket retraction action.

[0071] When the bucket dumps and unloads, the working pump 21 is unloaded, and the steering pump 22 supplies oil to the bucket reversing valve 32 of the working valve group. The electric control handle 131 communicates with the controller 13, and the controller 13 sends a current signal to the fourth hydraulic-controlled reversing valve 64, the first control reversing valve 71, and the second control reversing valve 72, causing the fourth hydraulic-controlled reversing valve 64, the first control reversing valve 71, and the second control reversing valve 72 to reverse. Specifically, the fourth hydraulic-controlled reversing valve 64 switches the oil path from the oil port P0 to the hydraulic-controlled end e4 of the bucket reversing valve 32. A pilot oil flow path passes through: the accumulator 4, the pressure reducing valve 11, the fourth hydraulic-controlled reversing valve 64, and the hydraulic-controlled end e4 of the bucket reversing valve 32, pushing the bucket reversing valve 32 to reverse. The bucket reversing valve 32 moves rightward, causing the valve core to move to the dumping position. Another pilot oil flow path passes through the accumulator 4, the pressure-reducing valve 11, the first control reversing valve 71, and the hydraulically controlled terminal e6 of the third control reversing valve 81. This drives the third control reversing valve 81, thereby opening the oil path between the steering pump 22 and port P0. Yet another pilot oil flow path passes through the accumulator 4, the pressure-reducing valve 11, the second control reversing valve 72, and the hydraulically controlled terminal e5 of the unloading reversing valve 51, thereby opening the unloading reversing valve 51. The hydraulic oil pumped by the working pump 21 flows through the working pump 21, the unloading reversing valve 51, and the oil tank 1, thereby unloading the hydraulic oil from the working pump 21. The hydraulic oil pumped by the steering pump 22 flows through: the steering pump 22, the third control reversing valve 81, the oil port P0, the bucket reversing valve 32, and the rodless chamber of the bucket cylinder 34, pushing the cylinder rod of the bucket cylinder 34 to retract, realizing the bucket tipping and unloading action.

[0072] When the boom is lowered and the bucket is retracted, the electric control handle 131 communicates with the controller 13, which sends current signals to the second control-end reversing valve, the third hydraulic-end reversing valve 63, the first control reversing valve 71, and the second control reversing valve 72, causing these valves to switch direction. Specifically, the second hydraulic-end reversing valve 62 switches the oil flow from port P0 to the hydraulic-controlled end e2 of the boom reversing valve 31, while the third hydraulic-end reversing valve 63 switches the oil flow from port P0 to the hydraulic-controlled end e3 of the bucket reversing valve 32. A pilot oil flow path passes through the accumulator 4, the pressure reducing valve 11, the second hydraulic-controlled reversing valve 62, and the hydraulic-controlled end e2 of the boom reversing valve 31, driving the boom reversing valve 31 to reverse direction. This causes the boom reversing valve 31 to shift rightward, causing the valve core to move to the lowered position. Another pilot oil flow path passes through the accumulator 4, the pressure-reducing valve 11, the third hydraulically controlled reversing valve 63, and the hydraulically controlled terminal e3 of the bucket reversing valve 32. This pushes the bucket reversing valve 32 to the left, shifting the valve core to the retracted position. Another pilot oil flow path passes through the accumulator 4, the pressure-reducing valve 11, the first control reversing valve 71, and the hydraulically controlled terminal e6 of the third control reversing valve 81. This pushes the third control reversing valve 81 to open the oil path between the steering pump 22 and port P0. Yet another pilot oil flow path passes through the accumulator 4, the pressure-reducing valve 11, the second control reversing valve 72, and the hydraulically controlled terminal e5 of the unloading reversing valve 51, pushing the unloading reversing valve 51 to open position. The hydraulic oil pumped by the working pump 21 flows through the working pump 21, the unloading reversing valve 51, and the oil tank 1, unloading the hydraulic oil from the working pump 21. One path of the hydraulic oil pumped by the steering pump 22 flows through the steering pump 22, the third control reversing valve 81, the oil port P0, the boom reversing valve 31, and the rodless chamber of the boom cylinder 33, pushing the rod of the boom cylinder 33 to retract and lower the boom. The other path of the hydraulic oil pumped by the steering pump 22 flows through the steering pump 22, the third control reversing valve 81, the oil port P0, the bucket reversing valve 32, and the rod chamber of the bucket cylinder 34, pushing the rod of the bucket cylinder 34 to extend and retract the bucket.

[0073] When the boom is lowered and the bucket is dumping, the electric control handle 131 communicates with the controller 13. The controller 13 sends current signals to the second control-end reversing valve, the fourth hydraulic-end reversing valve 64, the first control reversing valve 71, and the second control reversing valve 72, causing the second control-end reversing valve, the third hydraulic-end reversing valve 63, the first control reversing valve 71, and the second control reversing valve 72 to reverse direction. Specifically, the second hydraulic-end reversing valve 62 reverses the oil flow from port P0 to the hydraulic-controlled end e2 of the boom reversing valve 31, while the fourth hydraulic-controlled reversing valve 64 reverses the oil flow from port P0 to the hydraulic-controlled end e4 of the bucket reversing valve 32. A pilot oil flow path passes through the accumulator 4, the pressure reducing valve 11, the second hydraulic-controlled reversing valve 62, and the hydraulic-controlled end e2 of the boom reversing valve 31, driving the boom reversing valve 31 to reverse direction. The boom reversing valve 31 shifts rightward, causing the valve core to move to the lowered position. Another pilot oil flow path passes through the accumulator 4, the pressure-reducing valve 11, the fourth hydraulically controlled reversing valve 64, and the hydraulically controlled terminal e4 of the bucket reversing valve 32. This pushes the bucket reversing valve 32 in the reverse direction, shifting it rightward and moving the valve core to the tipping position. Another pilot oil flow path passes through the accumulator 4, the pressure-reducing valve 11, the first control reversing valve 71, and the hydraulically controlled terminal e6 of the third control reversing valve 81, pushing the third control reversing valve 81 in the reverse direction, thus opening the oil path between the steering pump 22 and port P0. Yet another pilot oil flow path passes through the accumulator 4, the pressure-reducing valve 11, the second control reversing valve 72, and the hydraulically controlled terminal e5 of the unloading reversing valve 51, pushing the unloading reversing valve 51 in the reverse direction. The hydraulic oil pumped by the working pump 21 flows through the working pump 21, the unloading reversing valve 51, and the oil tank 1, unloading the hydraulic oil from the working pump 21. One path of the hydraulic oil pumped by the steering pump 22 flows through the steering pump 22, the third control reversing valve 81, the oil port P0, the boom reversing valve 31, and the rodless chamber of the boom cylinder 33, pushing the rod of the boom cylinder 33 to retract, thus lowering the boom. Another path of the hydraulic oil pumped by the steering pump 22 flows through the steering pump 22, the third control reversing valve 81, the oil port P0, the bucket reversing valve 32, and the five-rod chamber of the bucket cylinder 34, pushing the rod of the bucket cylinder 34 to retract, thus enabling the bucket to tip and unload.

[0074] When the boom needs to float, the working pump 21 supplies oil to the boom reversing valve 31 of the working valve group, and the steering pump 22 does not supply oil. The electric control handle 131 communicates with the controller 13, and the controller 13 sends a current signal to the second hydraulic end reversing valve 62, so that the second hydraulic end reversing valve 62 and the second control reversing valve 72 are reversed. Specifically, the second hydraulic end reversing valve 62 switches the oil path from the oil port P0 to the hydraulic end e2 of the boom reversing valve 31. A pilot oil flow route is: accumulator 4, pressure reducing valve 11, second hydraulic end reversing valve 62, hydraulic end e2 of the boom reversing valve 31, pushing the boom reversing valve 31 to reverse, and the boom reversing valve 31 moves to the right to move the valve core to the floating position. Since there is no hydraulic oil at the hydraulic control end e6 of the third control reversing valve 81 at this time, the third control reversing valve 81 does not reverse, and there is no conduction between the steering pump 22 and the oil port P0. Therefore, the steering pump 22 only adjusts the displacement of the steering pump 22 according to the steering system Ls signal feedback to supply oil to the steering gear 9.

[0075] It is worth mentioning that although both boom floating and boom lowering require the controller 13 to send a current signal to the second hydraulic-controlled end reversing valve 62, since the valve core of the boom reversing valve 31 needs to be pushed to different working positions, the current signals sent by the controller 13 in these two situations are different.

[0076] When the boom is lowered and supporting the vehicle, the working pump 21 supplies oil to the boom reversing valve 31 of the working valve group, and the steering pump 22 does not supply oil to the working valve group. At this time, the electric control handle 131 communicates with the controller 13, and the controller 13 sends a current signal to the second hydraulic end reversing valve 62, causing the second hydraulic end reversing valve 62 to reverse. Specifically, the second hydraulic end reversing valve 62 reverses the oil path from the oil port P0 to the hydraulic end e2 of the boom reversing valve 31. The pilot oil flows through the route: accumulator 4, pressure reducing valve 11, second hydraulic end reversing valve 62, and hydraulic end e2 of the boom reversing valve 31, pushing the boom reversing valve 31 to reverse, and the boom reversing valve 31 moves to the right, causing the valve core to move to the lowered position. The hydraulic oil pumped by the working pump 21 flows through the working pump 21, oil port P0, the boom reversing valve 31, and the rod chamber of the boom cylinder 33, retracting the rod of the boom cylinder 33. Since there is no hydraulic oil at the hydraulic port e6 of the third control reversing valve 81 at this time, the third control reversing valve 81 does not switch direction, and there is no communication between the steering pump 22 and oil port P0. Therefore, the steering pump 22 only adjusts its displacement based on the steering system Ls signal feedback to supply oil to the steering gear 9.

[0077] When the loader is powered off but not off, and the boom is lowered, the electric control handle 131 communicates with the controller 13, which sends a current signal to the second hydraulically controlled reversing valve 62, causing it to reverse direction. Specifically, the second hydraulically controlled reversing valve 62 switches the oil path from port P0 to the hydraulically controlled end e2 of the boom reversing valve 31. Pilot oil flows through the accumulator 4, the pressure reducing valve 11, the second hydraulically controlled reversing valve 62, and the hydraulically controlled end e2 of the boom reversing valve 31, shifting the boom reversing valve 31. This shifts the valve core to the lowered position, causing the boom reversing valve 31 to shift rightward. The boom cylinder 33 descends due to the weight of the working device, the boom rodless chamber returns oil and replenishes oil to the rod chamber. After descending to the right position, the electric control handle 131 communicates with the controller 13, and the controller 13 stops sending the current signal to the second hydraulic end reversing valve 62, and the second hydraulic end reversing valve 62 loses power.

[0078] In summary, the loader hydraulic control system provided in this embodiment can realize the on-demand operation of the working pump 21 and the steering pump 22 through the coordinated control of the unloading valve group, the first control valve group, the second control valve group, and the third control valve group. The first control valve group is used to control the switching action of the boom reversing valve 31 and the bucket reversing valve 32, thereby realizing corresponding control of the loader lifting and the bucket retraction. The unloading valve group is used to control whether the working pump 21 is unloaded; the second control valve group is used to control whether the pilot oil of the accumulator 4 controls the opening of the unloading valve group; and the third control valve group is used to control whether the steering pump 22 is connected to the oil port P0, that is, whether the steering pump 22 is merged with the working pump 21. The working pump 21 and the steering pump 22 work on demand, thereby realizing the sequential distribution of the power of the entire hydraulic system. The system has a high degree of electronic control and is more energy-efficient.

[0079] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention and are not intended to limit the embodiments of the present invention. A person skilled in the art would be able to make various obvious changes, readjustments, and substitutions without departing from the scope of protection of the present invention. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A loader hydraulic control system, characterized in that: It comprises an oil tank (1), a working pump (21), a steering pump (22), a working valve group, an accumulator (4), an unloading valve group, a first control reversing valve group, a second control valve group and a third control valve group; wherein, The oil inlets of the working pump (21) and the steering pump (22) are connected to the oil tank (1); The working valve group includes a boom reversing valve (31) and a bucket reversing valve (32), the boom reversing valve (31) having a hydraulic control end e1 and a hydraulic control end e2, the bucket reversing valve (32) having a hydraulic control end e3 and a hydraulic control end e4, and the working valve group having an oil port P0, the oil port P0 being connected to the oil inlet of the boom reversing valve (31) and the bucket reversing valve (32); The working pump (21) is connected to the oil port P0, and the unloading valve group is provided on the connecting pipeline between the oil outlet of the working pump (21) and the oil port P0, and the unloading valve group is used to unload the working pump (21); The accumulator (4) can be connected to or disconnected from the hydraulic control end e1, the hydraulic control end e2, the hydraulic control end e3, and the hydraulic control end e4 respectively through the first control reversing valve group; The accumulator (4) can be connected to or disconnected from the unloading valve group through the second control valve group, and the unloading valve group can be opened when the accumulator (4) is connected to the unloading valve group; The steering pump (22) can be connected to or disconnected from the oil port P0 through the third control valve group.

2. The loader hydraulic control system according to claim 1, characterized in that: The unloading valve group comprises an unloading reversing valve (51) and a relief valve (52); the oil outlet of the working pump (21) is connected to the oil inlet of the unloading reversing valve (51) and the oil inlet of the relief valve (52); the oil outlet of the unloading reversing valve (51) is connected to the oil tank (1); and the oil outlet of the relief valve (52) is connected to the hydraulic control end e5 of the unloading reversing valve (51) and the oil tank (1); The accumulator (4) can be connected to or disconnected from the oil outlet of the unloading reversing valve (51) through the second control valve group.

3. The loader hydraulic control system according to claim 2, characterized in that: The unloading valve group further comprises a first one-way valve (53), which is configured to conduct hydraulic oil in a one-way direction from the oil inlet of the unloading reversing valve (51) to the oil inlet of the relief valve (52).

4. The loader hydraulic control system according to claim 1, characterized in that: The first control reversing valve group comprises a first hydraulic-controlled-end reversing valve (61), a second hydraulic-controlled-end reversing valve (62), a third hydraulic-controlled-end reversing valve (63) and a fourth hydraulic-controlled-end reversing valve (64); the accumulator (4) is respectively connected to the oil inlets of the first hydraulic-controlled-end reversing valve (61), the second hydraulic-controlled-end reversing valve (62), the third hydraulic-controlled-end reversing valve (63) and the fourth hydraulic-controlled-end reversing valve (64); the oil outlet of the first hydraulic-controlled-end reversing valve (61) is connected to the hydraulic-controlled end e1, the oil outlet of the second hydraulic-controlled-end reversing valve (62) is connected to the hydraulic-controlled end e2, the oil outlet of the third hydraulic-controlled-end reversing valve (63) is connected to the hydraulic-controlled end e3, and the oil outlet of the fourth hydraulic-controlled-end reversing valve (64) is connected to the hydraulic-controlled end e4.

5. The loader hydraulic control system according to claim 4, characterized in that: The first hydraulic-controlled-end reversing valve (61), the second hydraulic-controlled-end reversing valve (62), the third hydraulic-controlled-end reversing valve (63), and the fourth hydraulic-controlled-end reversing valve (64) are all configured as electromagnetic reversing valves.

6. The loader hydraulic control system according to claim 4, characterized in that: It also includes a pressure reducing valve (11), the accumulator (4) is connected to the oil inlet of the pressure reducing valve (11), and the oil outlet of the pressure reducing valve (11) is respectively connected to the oil inlets of the first hydraulic-controlled end reversing valve (61), the second hydraulic-controlled end reversing valve (62), the third hydraulic-controlled end reversing valve (63), and the fourth hydraulic-controlled end reversing valve (64).

7. The loader hydraulic control system according to claim 1, characterized in that: The second control valve group includes a first control reversing valve (71) and a second control reversing valve (72), and the third control valve group includes a third control reversing valve (81); wherein, The accumulator (4) is connected to the oil inlet of the first control reversing valve (71) and the oil inlet of the second control reversing valve (72); the oil outlet of the first control reversing valve (71) is connected to the hydraulic control end e6 of the third control reversing valve (81); the oil outlet of the second control reversing valve (72) is connected to the unloading valve group; the oil outlet of the steering pump (22) is connected to the oil inlet of the third control reversing valve (81); and the oil outlet of the third control reversing valve (81) is connected to the oil port P0.

8. The loader hydraulic control system according to claim 7, characterized in that: The invention also includes a steering gear (9) and a flow amplification valve (10), wherein the steering pump (22) is configured as a plunger pump, and an oil outlet of the steering pump (22) is connected to the steering gear (9) and the flow amplification valve (10), wherein the steering gear (9) has a first feedback oil port, and the flow amplification valve (10) has a second feedback oil port; The third control valve group further includes a shuttle valve (82), wherein a working oil port B1 of the shuttle valve (82) is connected to an oil outlet of the third control reversing valve (81), a working oil port B2 of the shuttle valve (82) is connected to the first feedback oil port and the second feedback oil port, and a working oil port B3 of the shuttle valve (82) is connected to a third feedback oil port of the steering pump (22), and the displacement of the steering pump (22) is adjusted according to the pressure of the third feedback oil port.

9. The loader hydraulic control system according to claim 8, characterized in that: A second one-way valve (83) is provided between the working oil port B3 of the shuttle valve (82) and the third feedback oil port. The second one-way valve (83) is configured to conduct hydraulic oil in a one-way direction from the working oil port B3 to the third feedback oil port.

10. The loader hydraulic control system according to claim 7, characterized in that: The first control reversing valve (71) and the second control reversing valve (72) are both configured as electromagnetic reversing valves.

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