A multi-pump hydraulic system for an electric loader and an electric loader

Abstract

The application discloses a kind of multi-pump hydraulic systems and electric loader for electric loader, it is related to electric engineering machinery technical field, including control valve, variable pump and constant delivery pump, control valve includes respectively connecting and driving swing boom oil cylinder, bucket oil cylinder and steering oil cylinder swing boom work link, bucket work link and steering work link;The output end of variable pump is connected with the oil inlet of swing boom work link in one way, is connected with the oil inlet of bucket work link by first flow amplification valve in one way, is connected with oil tank by cut-off valve in one way;The output end of constant delivery pump is connected with the oil inlet of swing boom work link by first flow amplification valve in one way, is connected with the oil inlet of bucket work link in one way, is connected with the oil inlet of steering work link in one way.The application realizes the confluence, shunt and decoupling of each work link by flow amplification valve, can solve the technical problems that a lot of throttling loss exists in traditional loader, engine power waste etc..

Description

[0001] This invention relates to the field of electric engineering machinery technology, and in particular to a multi-pump hydraulic system for an electric loader and an electric loader. Background Technology

[0002] As a core piece of equipment in engineering construction, the precise coordination of the hydraulic system and control valves of medium-tonnage loaders is crucial to ensuring efficient and stable operation. In the research and development and manufacturing of medium-tonnage loaders, the technological evolution of hydraulic systems and control valves has always revolved around core demands such as improving operational efficiency, reducing energy consumption, and optimizing the user experience.

[0003] In the context of traditional technology, loaders often employ fixed displacement pumps or simple dual-pump combined systems. The steering pump is primarily responsible for supplying oil to the steering cylinders via the steering control valve to control vehicle steering, while the work pump is primarily responsible for supplying oil to the boom and bucket cylinders via the work control valve to control the loading operation of the working device. This system architecture has significant limitations. When the flow required by the actuators (such as the boom and bucket) is less than the pump's rated flow, the excess hydraulic oil can only return to the oil tank through the relief valve, resulting in significant throttling losses and heat. Furthermore, under combined action conditions (lifting + bucket retraction), the flow distribution between the circuits is often not intelligent enough, easily leading to wasted engine power or sluggish operation. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-pump hydraulic system for electric loaders and an electric loader, solving the technical problems of large throttling losses and wasted engine power in traditional loaders.

[0005] To achieve the above objectives, the present invention is implemented using the following technical solution: In a first aspect, the present invention provides a multi-pump hydraulic system for an electric loader, comprising: Control valves, including boom working link, bucket working link and steering working link, which are respectively connected to and drive boom cylinder, bucket cylinder and steering cylinder; The variable pump has one output end connected to the oil inlet of the boom working link, another output end connected to the oil inlet of the bucket working link via the first flow amplification valve, and a third output end connected to the oil tank via the shut-off valve. A fixed displacement pump has one output end connected to the oil inlet of the boom working link via a first flow amplification valve, another output end connected to the oil inlet of the bucket working link, and a third output end connected to the oil inlet of the steering working link.

[0006] Optionally, the control shut-off valve and the first flow amplification valve are in the operating position; The variable pump flow rate enters the oil inlet of the boom working link; The flow rate from the fixed displacement pump enters the oil inlet of the boom working link through the first flow amplification valve, and merges with the flow rate from the variable displacement pump. If the boom working link is in its first working position, the confluenced oil enters the large chamber of the boom cylinder through the first working oil port of the boom working link, and the oil in the small chamber of the boom cylinder returns to the oil tank through the second working oil port and the return oil port of the boom working link, thus completing the boom lifting and confluence action. If the boom working link is in its second working position, the confluence oil enters the small chamber of the boom cylinder through the second working port of the boom working link, and the oil in the large chamber of the boom cylinder returns to the oil tank through the first working port and return port of the boom working link, thus completing the boom lowering and confluence action.

[0007] Optionally, the oil inlet of the boom working link is connected to the shut-off end of the first check valve. When the boom rises and merges or descends and merges, the flow rates of the variable pump and the fixed pump merge at the open end of the first check valve.

[0008] Optionally, the variable pump and fixed displacement pump are controlled to idle, and the idle flow of the variable pump and fixed displacement pump is returned to the oil tank through the shut-off valve; The boom working link is controlled to be in its third working position, and the first and second working oil ports of the boom working link are connected. Under the influence of gravity, the oil in the large chamber of the boom cylinder enters the small chamber of the boom cylinder through the first and second working ports of the boom working link, completing the complete regeneration and descent of the boom.

[0009] Optionally, the boom working link has a second return oil port. When the boom working link is in its third working position, both its first working oil port and its second working oil port are connected to the second return oil port. The second return port is connected to the open end of the second check valve, and the closed end of the second check valve is connected to the oil tank. When the boom is fully regenerated and falls, the excess oil in the large chamber of the boom cylinder relative to its small chamber returns to the oil tank through the second return port and the second check valve.

[0010] Optionally, the control shut-off valve and the first flow amplification valve are in the operating position; The flow rate from the variable pump enters the inlet of the bucket working link via the first flow amplification valve; The flow rate from the fixed displacement pump enters the oil inlet of the bucket working assembly and merges with the flow rate from the variable displacement pump. If the bucket working link is in its first working position, the combined oil enters the large chamber of the bucket cylinder through the first working oil port of the bucket working link, and the oil in the small chamber of the bucket cylinder returns to the oil tank through the second working oil port and the return oil port of the bucket working link, thus completing the bucket retraction and merging action. If the bucket working link is in its second working position, the confluenced oil enters the small chamber of the bucket cylinder through the second working port of the bucket working link, and the oil in the large chamber of the bucket cylinder returns to the oil tank through the first working port and return port of the bucket working link, thus completing the bucket tipping and confluence action.

[0011] Optionally, the variable pump is controlled to idle, and the idle flow of the variable pump returns to the oil tank through a shut-off valve; The flow rate from the fixed displacement pump enters the oil inlet of the steering linkage; If the steering linkage is in the first working position, the flow rate of the fixed displacement pump enters the steering cylinder through the first working port of the steering linkage. After working, the oil returns to the oil tank through the second working port and the return port of the steering linkage, completing the left turn action. If the steering linkage is in the second working position, the flow rate of the fixed displacement pump enters the steering cylinder through the second working port of the steering linkage. After operation, the oil returns to the oil tank through the first working port and the return port of the steering linkage, completing the right turn action.

[0012] Optionally, a second flow amplification valve may also be included. The output end of the variable pump is connected to the oil inlet of the bucket working assembly via a first flow amplification valve; The output of the metering pump is connected to the oil inlet of the boom working assembly via a second flow amplification valve and a first flow amplification valve, and also connected to the oil inlet of the bucket working assembly via a second flow amplification valve.

[0013] Optionally, pilot solenoid valves are connected to the boom working link, the bucket working link, and the steering working link; the oil inlet of the pilot solenoid valve is connected to the output end of the pilot pump, and the oil return port is connected to the oil tank.

[0014] Secondly, the present invention provides an electric loader, including the multi-pump hydraulic system for an electric loader as described above.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: This invention provides a multi-pump hydraulic system and an electric loader, employing a multi-pump hydraulic system architecture to meet the application requirements of medium-tonnage loaders. The steering, bucket, and boom are integrated into a single unit, simplifying the overall piping layout. The main valve features dual-pump inlet: a variable displacement pump supplies oil to the boom and bucket, while a fixed displacement pump supplies oil to the steering and bucket. This allows for separate supply of oil to the boom and bucket by the variable displacement and fixed displacement pumps, respectively. The variable displacement pumps are connected in parallel, and a logic valve decouples the loads of the boom and bucket. The fixed displacement pumps are connected in a series-parallel composite layout, with the steering and bucket pumps connected in parallel. The hydraulic system incorporates a logic valve to decouple steering from bucket load, and a series hydraulic circuit for steering and bucket operation to prioritize steering. A variable displacement pump enables combined adjustment and control of motor and pump displacement, while a fixed displacement pump reduces costs. The variable and fixed displacement pumps are configured with varying displacements, with the fixed displacement pump having a smaller displacement to meet steering requirements. The variable displacement pump selection depends on the fixed displacement pump, and the combined flow of the variable and fixed displacement pumps meets the maximum flow requirements of the superstructure. A fully regenerative boom lowering design includes an independent regeneration hydraulic passage and back pressure valve. During full boom lowering, the large chamber is replenished with oil, and the main pump does not supply oil, reducing losses. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the multi-pump hydraulic system for an electric loader provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the multi-pump hydraulic system for electric loaders provided in Embodiment 2 of the present invention; The diagram is marked as follows: 1. Control valve; 101. Boom working link; 102. Bucket working link; 103. Steering working link; 2. Variable displacement pump; 3. Fixed displacement pump; 4. Boom cylinder; 5. Bucket cylinder; 6. Steering cylinder; 7. Shut-off valve; 8. First flow amplifier valve; 9. Second flow amplifier valve; 10. First check valve; 11. Second check valve; 12. Third check valve; 13. Fourth check valve; 14. Oil tank; 15. Pilot pump. Detailed Implementation

[0017] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0018] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are used only for the convenience of describing the invention and simplifying the description, 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, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] Example 1

[0021] like Figure 1 As shown, this embodiment of the invention provides a multi-pump hydraulic system for an electric loader, including a control valve 1, a variable displacement pump 2, and a fixed displacement pump 3. The control valve 1 includes a boom working link 101, a bucket working link 102, and a steering working link 103, which are respectively connected to the boom cylinder 4, the bucket cylinder 5, and the steering cylinder 6. The output end of the variable displacement pump 2 is connected to the oil inlet of the boom working link 101, the oil inlet of the bucket working link 102 via a first flow amplification valve 8, and the oil tank 14 via a shut-off valve 7. The input end of the variable displacement pump 2 is connected to the oil tank 14. The output end of the fixed displacement pump 3 is connected to the oil inlet of the boom working link 101 via the first flow amplification valve 8, the oil inlet of the bucket working link 102, and the oil inlet of the steering working link 103. The input end of the fixed displacement pump 3 is connected to the oil tank 14.

[0022] In other alternative embodiments, the boom working link 101, bucket working link 102, and steering working link 103 are equipped with through-flow channels. The flow direction of the through-flow channels in the boom working link 101 and bucket working link 102 is the same as the flow direction of the variable pump, and the flow direction of the through-flow channel in the steering working link 103 is the same as the flow direction of the fixed displacement pump. The through-flow channels are used to deliver the upstream oil "unchanged" to the next working link, while allowing the current working link to draw oil from this main channel as needed through the valve core.

[0023] Based on the through-flow channel, the output end of the variable pump 2 is connected to the oil inlet of the boom working link 101 in one way, the oil inlet of the bucket working link 102 in another way via the first flow amplification valve 8, and the oil tank 14 in another way via the through-flow channel of the boom working link 101, the through-flow channel of the bucket working link 102, and the shut-off valve 7; the output end of the fixed displacement pump 3 is connected to the oil inlet of the boom working link 101 in one way via the through-flow channel of the steering working link 103 and the first flow amplification valve 8, the oil inlet of the bucket working link 102 in another way via the through-flow channel of the steering working link 103, and the oil inlet of the steering working link 103 in yet another way.

[0024] In other alternative embodiments, pilot solenoid valves are connected to the boom coupling 101, bucket coupling 102, and steering coupling 103; the inlet of the pilot solenoid valve is connected to the output of the pilot pump 15, and the return port is connected to the oil tank 14. The pilot solenoid valves are used to control the working positions of the boom coupling 101, bucket coupling 102, and steering coupling 103.

[0025] The working principle of the multi-pump hydraulic system for electric loaders provided in this embodiment of the invention is as follows: (1) Idle: In the idle state, the bucket working coupling 102, the steering working coupling 103, the first flow amplification valve 8, and the shut-off valve 7 are all in the neutral position, and the boom working coupling 101 is in the idle position, that is, the first working oil port and the second working oil port of the boom working coupling 101 are locked, the boom cylinder 4 is stopped, and the neutral idle flow provided by the variable pump 2 and the fixed pump 3 cannot enter the actuators (boom cylinder 4, bucket cylinder 5 and steering cylinder 6) to do work, but can only return to the oil tank 14 through the shut-off valve 7.

[0026] (2) Boom raising / lowering confluence: Control the shut-off valve 7 and the first flow amplification valve 8 to be in the working position; The variable pump flow rate enters the oil inlet of boom working link 101; The flow rate from the fixed displacement pump enters the oil inlet of the boom working link 101 through the first flow amplification valve 8, and merges with the flow rate from the variable displacement pump. If the boom working link 101 is in its first working position, the confluence oil enters the large chamber of the boom cylinder 4 through the first working oil port of the boom working link 101, and the oil in the small chamber of the boom cylinder 4 returns to the oil tank 14 through the second working oil port and the return oil port of the boom working link 101, thus completing the boom lifting and confluence action. If the boom working link 101 is in its second working position, the confluence oil enters the small chamber of the boom cylinder 4 through the second working oil port of the boom working link 101, and the oil in the large chamber of the boom cylinder 4 returns to the oil tank 14 through the first working oil port and the return oil port of the boom working link 101, thus completing the boom lowering and confluence action.

[0027] In the boom raising / lowering flow control, the flow rate entering the boom cylinder 4 can be adjusted by adjusting the opening of the first flow amplification valve 8.

[0028] In other alternative embodiments, the oil inlet of the boom working link 101 is connected to the shut-off end of the first check valve 10. During boom raising and lowering flow merging operations, the flow rates of the variable pump and the fixed-displacement pump are merged at the open end of the first check valve 10. The first check valve 10 can protect the variable pump 2 and the fixed-displacement pump 3 from reverse impact and ensure the stability of the merged flow rates of the variable pump and the fixed-displacement pump.

[0029] (3) The boom fully regenerates and falls: The variable pump 2 and the fixed pump 3 are kept in an idle state, and the idle flow of the variable pump 2 and the fixed pump 3 returns to the oil tank 14 through the shut-off valve 7; The boom working link 101 is controlled to be in its third working position, and the first working oil port and the second working oil port of the boom working link 101 are connected. Under the action of gravity, the oil in the large chamber of the boom cylinder 4 enters the small chamber of the boom cylinder 4 through the first and second working oil ports of the boom working link 101. The entire process does not require the variable pump 2 and the fixed pump 3 to provide flow to complete the complete regeneration and descent of the boom.

[0030] In other optional embodiments, the boom working link 101 has a second return port. When the boom working link 101 is in its third working position, both its first working port and second working port are connected to the second return port. The second return port is connected to the conducting end of the second one-way valve 11, and the closing end of the second one-way valve 11 is connected to the oil tank 14. When the boom is fully regenerated and falls, the excess oil in the large chamber of the boom cylinder 4 relative to its small chamber returns to the oil tank 14 through the second return port and the second one-way valve 11.

[0031] The second check valve 11 provides a certain back pressure, which can control the amount of boom regeneration.

[0032] (4) Bucket retraction / tipping bucket merge: Control the shut-off valve 7 and the first flow amplification valve 8 to be in the working position; The flow rate from the variable pump enters the oil inlet of the bucket working link 102 via the first flow amplification valve 8; The flow rate from the fixed displacement pump enters the oil inlet of the bucket working assembly 102 and merges with the flow rate from the variable displacement pump. If the bucket working link 102 is in its first working position, the combined oil enters the large chamber of the bucket cylinder 5 through the first working oil port of the bucket working link 102, and the oil in the small chamber of the bucket cylinder 5 returns to the oil tank 14 through the second working oil port and the return oil port of the bucket working link 102, thus completing the bucket retraction and merging action. If the control bucket working link 102 is in its second working position, the combined oil enters the small cavity of the bucket cylinder 5 through the second working oil port of the bucket working link 102, and the oil in the large cavity of the bucket cylinder 5 returns to the oil tank 14 through the first working oil port and the return oil port of the bucket working link 102, thus completing the bucket tipping and merging action.

[0033] In the bucket retraction / tipping confluence control, the flow rate entering the bucket cylinder 5 can be adjusted by regulating the opening of the first flow amplification valve 8.

[0034] In other alternative embodiments, the oil inlet of the bucket working link 102 is connected to the shut-off end of the third check valve 12. During the bucket's upward or downward flow merging action, the flow rates of the variable pump and the fixed displacement pump are merged at the open end of the third check valve 12. The third check valve 12 can protect the variable pump 2 and the fixed displacement pump 3 from reverse impact and ensure the stability of the merged flow rates of the variable pump and the fixed displacement pump.

[0035] (5) Turn left / right: The variable pump 2 is kept in an idle state, and the idle flow of the variable pump 2 returns to the oil tank 14 through the shut-off valve 7; The flow rate from the fixed displacement pump enters the oil inlet of the steering coupling 103; If the steering linkage 103 is in the first working position, the flow rate of the fixed displacement pump enters the steering cylinder 6 through the first working oil port of the steering linkage 103. After working, the oil returns to the oil tank 14 through the second working oil port and the return oil port of the steering linkage 103, thus completing the left turn action. If the steering linkage 103 is in the second working position, the flow rate of the fixed displacement pump enters the steering cylinder 6 through the second working port of the steering linkage 103. After working, the oil returns to the oil tank 14 through the first working port and the return port of the steering linkage 103, completing the right turn action.

[0036] In other alternative embodiments, the oil inlet of the steering coupling 103 is connected to the shut-off end of the fourth check valve 13 to protect the metering pump 3 from reverse impact.

[0037] (6) Combined boom raising and bucket retraction: Control shut-off valve 7 to be in the working position; The variable pump flow rate enters the oil inlet of boom working link 101; The flow rate from the metering pump enters the oil inlet of the bucket working assembly 102; The boom working link 101 and the bucket working link 102 are both in their first working positions. The variable pump flow rate enters the large chamber of the boom cylinder 4 through the first working port of the boom working link 101, and the oil in the small chamber of the boom cylinder 4 returns to the oil tank 14 through the second working port and the return port of the boom working link 101. The fixed pump flow rate enters the large chamber of the bucket cylinder 5 through the first working port of the bucket working link 102, and the oil in the small chamber of the bucket cylinder 5 returns to the oil tank 14 through the second working port and the return port of the bucket working link 102, thus completing the boom raising + bucket retracting combined action.

[0038] When the boom and bucket operate in combination, the variable displacement pump supplies the flow rate to the boom working link 101, and the fixed displacement pump supplies the flow rate to the bucket working link 102, thus decoupling the boom lifting and bucket retraction combined actions. The working principle of the boom lifting + bucket tipping combined action, the boom lowering + bucket retraction combined action, and the boom lowering + bucket tipping combined action is the same.

[0039] (7) Left turn + boom raising combination: Control shut-off valve 7 to be in the working position; The variable pump flow rate enters the oil inlet of boom working link 101; The flow rate from the fixed displacement pump enters the oil inlet of the steering coupling 103; The boom working link 101 and the steering working link 103 are both in their first working positions. The variable pump flow enters the large chamber of the boom cylinder 4 through the first working port of the boom working link 101. The oil in the small chamber of the boom cylinder 4 returns to the oil tank 14 through the second working port and the return port of the boom working link 101. The fixed pump flow enters the steering cylinder 6 through the first working port of the steering working link 103. After operation, the oil returns to the oil tank 14 through the second working port and the return port of the steering working link 103, completing the left turn + boom raising combined action.

[0040] The working principle of the left turn + boom lowering compound action, the right turn + boom raising compound action, and the right turn + boom lowering compound action is the same.

[0041] (8) Left turn + bucket retraction combination: Control the shut-off valve 7 and the first flow amplification valve 8 to be in the working position; The flow rate from the variable pump enters the oil inlet of the bucket working link 102 via the first flow amplification valve 8; The flow rate from the fixed displacement pump enters the oil inlet of the steering coupling 103; The control bucket working link 102 is in its first working position, the steering working link 103 is in its first working position, the variable pump flow enters the large chamber of the bucket cylinder 5 through the first working oil port of the bucket working link 102, and the oil in the small chamber of the bucket cylinder 5 returns to the oil tank 14 through the second working oil port and the return oil port of the bucket working link 102; the fixed pump flow enters the steering cylinder 6 through the first working oil port of the steering working link 103, and after operation, the oil returns to the oil tank 14 through the second working oil port and the return oil port of the steering working link 103, completing the left turn + bucket retraction combined action.

[0042] The working principles of the left turn + bucket tipping combined action, the right turn + bucket retraction combined action, and the right turn + bucket tipping combined action are the same.

[0043] (9) Left turn + boom lifting + bucket retraction combination: Control the shut-off valve 7 and the first flow amplification valve 8 to be in the working position; A portion of the flow from variable pump 2 enters boom working link 101, while the other portion enters the oil inlet of bucket working link 102 via the first flow amplification valve 8. The flow rate from the fixed displacement pump enters the oil inlet of the steering coupling 103; The boom working coupling 101, bucket working coupling 102, and steering working coupling 103 are all in their first working positions. A portion of the flow from variable pump 2 enters the large chamber of boom cylinder 4 through the first working port of boom coupling 101. The oil in the small chamber of boom cylinder 4 returns to the oil tank 14 through the second working port and return port of boom coupling 101. Another portion of the flow from variable pump 2 enters the large chamber of bucket cylinder 5 through the first working port of bucket coupling 102. The oil in the small chamber of bucket cylinder 5 returns to the oil tank 14 through the second working port and return port of bucket coupling 102. The flow from fixed displacement pump enters the steering cylinder 6 through the first working port of steering coupling 103. After operation, the oil returns to the oil tank 14 through the second working port and return port of steering coupling 103, completing the left turn + boom lifting + bucket retraction combined action. The working principle of the other three combined actions is the same. The flow distribution between boom cylinder 4 and bucket cylinder 5 can be adjusted by regulating the opening of the first flow amplification valve 8.

[0044] Example 2

[0045] like Figure 2 As shown, based on the multi-pump hydraulic system for electric loaders provided in Embodiment 1, this embodiment of the invention adds a second flow amplification valve 9. The output end of the variable pump 2 is connected to the oil inlet of the bucket working link 102 via the first flow amplification valve 8; the output end of the fixed displacement pump 3 is connected to the oil inlet of the boom working link 101 via the second flow amplification valve 9 and the first flow amplification valve 8, and also connected to the oil inlet of the bucket working link 102 via the second flow amplification valve 9.

[0046] Compared with Example 1, the biggest difference in Example 2 is that the steering linkage 103 and the bucket linkage 102 adopt parallel oil circuits.

[0047] The working principle of the multi-pump hydraulic system for electric loaders provided in this embodiment of the invention is as follows: (1) Idle: In the idle state, the bucket working coupling 102, steering working coupling 103, first flow amplification valve 8, second flow amplification valve 9, and shut-off valve 7 are all in the neutral position, and the boom working coupling 101 is in the idle position, that is, the first and second working oil ports of the boom working coupling 101 are locked, the boom cylinder 4 is stopped, and the neutral idle flow provided by the variable pump 2 and the fixed displacement pump 3 cannot enter the actuators (boom cylinder 4, bucket cylinder 5, and steering cylinder 6) to do work, but can only return to the oil tank 14 through the shut-off valve 7.

[0048] (2) Boom raising / lowering confluence: Control the shut-off valve 7, the first flow amplification valve 8, and the second flow amplification valve 9 to be in the working position; The variable pump flow rate enters the oil inlet of boom working link 101; The flow rate from the fixed displacement pump enters the oil inlet of the boom working link 101 through the second flow amplification valve 9 and the first flow amplification valve 8, and merges with the flow rate from the variable displacement pump. If the boom working link 101 is in its first working position, the confluence oil enters the large chamber of the boom cylinder 4 through the first working oil port of the boom working link 101, and the oil in the small chamber of the boom cylinder 4 returns to the oil tank 14 through the second working oil port and the return oil port of the boom working link 101, thus completing the boom lifting and confluence action. If the boom working link 101 is in its second working position, the confluence oil enters the small chamber of the boom cylinder 4 through the second working oil port of the boom working link 101, and the oil in the large chamber of the boom cylinder 4 returns to the oil tank 14 through the first working oil port and the return oil port of the boom working link 101, thus completing the boom lowering and confluence action.

[0049] In the boom raising / lowering flow control, the flow rate entering the boom cylinder 4 can be adjusted by regulating the opening of the first flow amplification valve 8 and the second flow amplification valve 9.

[0050] (3) Boom fully regenerated and dropped: Same as in Example 1.

[0051] (4) Bucket retraction / tipping bucket merge: Control shut-off valve 7, first flow amplification valve 8, and second flow amplification valve 9 to be in the working position; The flow rate from the variable pump enters the oil inlet of the bucket working link 102 via the first flow amplification valve 8; The flow rate from the fixed displacement pump enters the oil inlet of the bucket working link 102 through the second flow amplification valve 9, and merges with the flow rate from the variable displacement pump. If the bucket working link 102 is in its first working position, the combined oil enters the large chamber of the bucket cylinder 5 through the first working oil port of the bucket working link 102, and the oil in the small chamber of the bucket cylinder 5 returns to the oil tank 14 through the second working oil port and the return oil port of the bucket working link 102, thus completing the bucket retraction and merging action. If the control bucket working link 102 is in its second working position, the combined oil enters the small cavity of the bucket cylinder 5 through the second working oil port of the bucket working link 102, and the oil in the large cavity of the bucket cylinder 5 returns to the oil tank 14 through the first working oil port and the return oil port of the bucket working link 102, thus completing the bucket tipping and merging action.

[0052] In the bucket retraction / tipping confluence control, the flow rate entering the bucket cylinder 5 can be adjusted by regulating the opening of the first flow amplification valve 8 and the second flow amplification valve 9.

[0053] (5) Left / right turn: Same as in Example 1.

[0054] (6) Combined boom raising and bucket retraction: Control shut-off valve 7 and second flow amplification valve 9 to be in the working position; The variable pump flow rate enters the oil inlet of boom working link 101; The flow rate from the fixed displacement pump enters the oil inlet of the bucket working link 102 through the second flow amplification valve 9; The boom working link 101 and the bucket working link 102 are both in their first working positions. The variable pump flow rate enters the large chamber of the boom cylinder 4 through the first working port of the boom working link 101, and the oil in the small chamber of the boom cylinder 4 returns to the oil tank 14 through the second working port and the return port of the boom working link 101. The fixed pump flow rate enters the large chamber of the bucket cylinder 5 through the first working port of the bucket working link 102, and the oil in the small chamber of the bucket cylinder 5 returns to the oil tank 14 through the second working port and the return port of the bucket working link 102, thus completing the boom raising + bucket retracting combined action.

[0055] When the boom and bucket operate in combination, the variable displacement pump supplies the flow rate to the boom working link 101, and the fixed displacement pump supplies the flow rate to the bucket working link 102, thus decoupling the boom lifting and bucket retraction combined actions. The working principle of the boom lifting + bucket tipping combined action, the boom lowering + bucket retraction combined action, and the boom lowering + bucket tipping combined action is the same.

[0056] (7) Left turn + boom rise combination: Same as in Example 1.

[0057] (8) Left turn + bucket retraction combination: Same as in Example 1.

[0058] (9) Left turn + boom lifting + bucket retraction combination: Same as in Example 1.

[0059] Example 3

[0060] Based on the multi-pump hydraulic system for electric loaders provided in Embodiment 1 or Embodiment 2, this embodiment of the invention provides an electric loader, including the multi-pump hydraulic system for electric loaders as described above.

[0061] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A multi-pump hydraulic system for an electric loader, characterized in that, include: Control valves, including boom working link, bucket working link and steering working link, which are respectively connected to and drive boom cylinder, bucket cylinder and steering cylinder; The variable pump has one output end connected to the oil inlet of the boom working link, another output end connected to the oil inlet of the bucket working link via the first flow amplification valve, and a third output end connected to the oil tank via the shut-off valve. A fixed displacement pump has one output end connected to the oil inlet of the boom working link via a first flow amplification valve, another output end connected to the oil inlet of the bucket working link, and a third output end connected to the oil inlet of the steering working link.

2. The multi-pump hydraulic system for electric loaders according to claim 1, characterized in that, The control shut-off valve and the first flow amplification valve are in the working position; The variable pump flow rate enters the oil inlet of the boom working link; The flow rate from the fixed displacement pump enters the oil inlet of the boom working link through the first flow amplification valve, and merges with the flow rate from the variable displacement pump. If the boom working link is in its first working position, the confluenced oil enters the large chamber of the boom cylinder through the first working oil port of the boom working link, and the oil in the small chamber of the boom cylinder returns to the oil tank through the second working oil port and the return oil port of the boom working link, thus completing the boom lifting and confluence action. If the boom working link is in its second working position, the confluence oil enters the small chamber of the boom cylinder through the second working port of the boom working link, and the oil in the large chamber of the boom cylinder returns to the oil tank through the first working port and return port of the boom working link, thus completing the boom lowering and confluence action.

3. The multi-pump hydraulic system for electric loaders according to claim 2, characterized in that, The oil inlet of the boom working link is connected to the shut-off end of the first check valve. When the boom rises and merges or descends and merges, the flow rates of the variable pump and the fixed pump merge at the open end of the first check valve.

4. The multi-pump hydraulic system for an electric loader according to claim 1, characterized in that, The variable pump and fixed displacement pump are kept in idle state, and the idle flow of the variable pump and fixed displacement pump is returned to the oil tank through the shut-off valve; The boom working link is controlled to be in its third working position, and the first and second working oil ports of the boom working link are connected. Under the influence of gravity, the oil in the large chamber of the boom cylinder enters the small chamber of the boom cylinder through the first and second working ports of the boom working link, completing the complete regeneration and descent of the boom.

5. The multi-pump hydraulic system for an electric loader according to claim 1, characterized in that, The boom working link has a second return oil port. When the boom working link is in its third working position, both its first working oil port and its second working oil port are connected to the second return oil port. The second return port is connected to the open end of the second check valve, and the closed end of the second check valve is connected to the oil tank. When the boom is fully regenerated and falls, the excess oil in the large chamber of the boom cylinder relative to its small chamber returns to the oil tank through the second return port and the second check valve.

6. The multi-pump hydraulic system for an electric loader according to claim 1, characterized in that, The control shut-off valve and the first flow amplification valve are in the working position; The flow rate from the variable pump enters the inlet of the bucket working link via the first flow amplification valve; The flow rate from the fixed displacement pump enters the oil inlet of the bucket working assembly and merges with the flow rate from the variable displacement pump. If the bucket working link is in its first working position, the combined oil enters the large chamber of the bucket cylinder through the first working oil port of the bucket working link, and the oil in the small chamber of the bucket cylinder returns to the oil tank through the second working oil port and the return oil port of the bucket working link, thus completing the bucket retraction and merging action. If the bucket working link is in its second working position, the confluenced oil enters the small chamber of the bucket cylinder through the second working port of the bucket working link, and the oil in the large chamber of the bucket cylinder returns to the oil tank through the first working port and return port of the bucket working link, thus completing the bucket tipping and confluence action.

7. The multi-pump hydraulic system for an electric loader according to claim 1, characterized in that, The variable pump is kept in idle state, and the idle flow of the variable pump returns to the oil tank through the shut-off valve; The flow rate from the fixed displacement pump enters the oil inlet of the steering linkage; If the steering linkage is in the first working position, the flow rate of the fixed displacement pump enters the steering cylinder through the first working port of the steering linkage. After working, the oil returns to the oil tank through the second working port and the return port of the steering linkage, completing the left turn action. If the steering linkage is in the second working position, the flow rate of the fixed displacement pump enters the steering cylinder through the second working port of the steering linkage. After operation, the oil returns to the oil tank through the first working port and the return port of the steering linkage, completing the right turn action.

8. The multi-pump hydraulic system for an electric loader according to claim 1, characterized in that, It also includes a second flow amplification valve. The output end of the variable pump is connected to the oil inlet of the bucket working assembly via a first flow amplification valve; The output of the metering pump is connected to the oil inlet of the boom working assembly via a second flow amplification valve and a first flow amplification valve, and also connected to the oil inlet of the bucket working assembly via a second flow amplification valve.

9. The multi-pump hydraulic system for an electric loader according to claim 1, characterized in that, Pilot solenoid valves are connected to the boom working link, the bucket working link, and the steering working link; the oil inlet of the pilot solenoid valve is connected to the output end of the pilot pump, and the oil return port is connected to the oil tank.

10. An electric loader, characterized in that, Including the multi-pump hydraulic system for electric loaders as described in any one of claims 1-9.

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