CN215927958U - Constant-variable flow-dividing and flow-dividing hydraulic control system and loader - Google Patents
Constant-variable flow-dividing and flow-dividing hydraulic control system and loader Download PDFInfo
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- CN215927958U CN215927958U CN202121443223.7U CN202121443223U CN215927958U CN 215927958 U CN215927958 U CN 215927958U CN 202121443223 U CN202121443223 U CN 202121443223U CN 215927958 U CN215927958 U CN 215927958U
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Abstract
The utility model relates to a hydraulic system, aiming at solving the problems of frequent opening and unstable pressure of an unloading valve in a constant variable on-off flow hydraulic control system of the existing loader, the utility model constructs the constant variable on-off flow hydraulic control system and the loader, wherein the constant variable on-off flow hydraulic control system comprises an adjustable overflow valve with adjustable overflow pressure; two ends of the adjustable overflow valve are respectively connected with a quantitative pressure oil source and a hydraulic oil tank, and the overflow opening pressure of the adjustable overflow valve is slightly lower than the unloading opening preset unloading pressure of the unloading valve bank. When the gear pump is independently used for supplying oil for the multi-way valve rotating bucket, the load rises, the adjustable overflow valve overflows, the unloading valve is not opened, the phenomenon that the pressure rises repeatedly and decreases is avoided, the flow change is stable, different overflow pressures are set through the adjustable overflow valve, and the gear pump is suitable for different working conditions.
Description
Technical Field
The utility model relates to a hydraulic system, in particular to a constant and variable flow dividing and combining hydraulic system and a loader.
Background
The hydraulic system of the working device of the loader usually adopts a fixed variable hydraulic system, namely a fixed displacement pump (such as a gear pump) and a variable displacement pump (such as a plunger pump) are adopted for supplying oil. When the composite operation of the boom lifting action and the bucket retracting action is performed, oil from the variable pump enters the swing arm oil cylinder through a boom linkage main valve in the multi-way valve, and oil from the fixed pump enters the swing arm oil cylinder through the swing arm linkage main valve in the multi-way valve, so that the two pumps are separately supplied with oil, and the respective actions do not interfere with each other.
In the multi-way valve, the maximum pressure value of a quantitative oil inlet oil way connected with a constant delivery pump is regulated by an electric proportional valve connected with the quantitative oil inlet oil way, the maximum pressure value of a variable oil inlet oil way connected with a variable pump is regulated by the pressure cut-off of the variable pump, the maximum system pressure when a rotating bucket joint acts independently is regulated by an LS overflow valve, and the opening and closing of an unloading valve are controlled by a control signal K, so that the oil of the constant delivery pump is controlled to enter an oil cylinder or an oil return tank, and the energy-saving effect is achieved. In the existing hydraulic system, the control logic of an unloading valve control signal K is unclear, the working principle of the unloading valve is unclear, and the pressure adjustment of the system is inconvenient; the problems make the system flow difficult to provide according to the requirement, the phenomena of frequent and uncontrollable opening of the unloading valve, unstable flow supply and pressure pulse are easy to occur, the actual working condition requirement is difficult to meet, and the service life of elements is reduced.
SUMMERY OF THE UTILITY MODEL
The utility model provides a constant-variable on-off fluid control system and a loader, aiming at solving the technical problems that an unloading valve in the conventional constant-variable on-off fluid control system of the loader is likely to be frequently opened and the pressure is unstable, so that the unloading valve is prevented from being frequently opened and closed during unloading, and the pressure is stable.
The technical scheme for realizing the purpose of the utility model is as follows: constructing a fixed-variable and variable-flow dividing and converging hydraulic control system, which comprises a variable pressure oil source, a fixed pressure oil source, a multi-way valve, a first hydraulic actuating element, a second hydraulic actuating element, an unloading valve group and a hydraulic oil tank, wherein the multi-way valve comprises a first joint main valve for controlling the first hydraulic actuating element and a second joint main valve for controlling the second hydraulic actuating element; two confluence oil paths which respectively pass through a first main valve middle oil path and a second main valve middle oil path are arranged between the first main valve oil inlet and the second main valve oil inlet; when the single-action operation is carried out, the first main joint valve and the second main joint valve are both in the middle position, and the middle position confluence oil circuit of the main valve which is not reversed in the first main joint valve and the second main joint valve is communicated, so that the confluence oil supply of the quantitative pressure oil source and the variable pressure oil source is realized. When the two-linkage main valves are operated in a reversing mode, the middle position confluence oil circuit of the two-linkage main valves is cut off, so that the quantitative pressure oil source can supply oil to the second hydraulic execution part through the second-linkage main valves, and the variable pressure oil source supplies oil to the first hydraulic execution part through the first-linkage main valves.
The unloading valve group comprises a one-way valve, an unloading valve and an unloading opening valve; the oil inlet and outlet ends of the one-way valve are respectively connected with an oil inlet and an oil outlet of the unloading valve group; the oil inlet and outlet ends of the unloading valve are respectively connected with an oil inlet and an unloading port of the unloading valve group; and the oil inlet and outlet ends of the unloading opening valve are respectively connected with the oil outlet end of the one-way valve and the hydraulic control end of the unloading valve.
The quantitative pressure oil source is connected with an oil inlet of the unloading valve bank, and an oil outlet of the unloading valve bank is connected with an oil inlet of the second main valve; the unloading port of the unloading valve group is communicated with an oil return oil way communicated with the hydraulic oil tank.
When the pressure of the oil inlet end of the unloading opening valve is higher than the preset unloading pressure, the oil outlet end outputs the preset pressure for opening the unloading valve; when the single-action operation is carried out, when the load on the first hydraulic executing part or the second hydraulic executing part or the load on the first hydraulic executing part during the composite action reaches a preset value, the unloading opening valve leads the pressure to the hydraulic control end of the unloading valve to open the unloading valve, and the oil of the quantitative pressure oil source directly flows back to the hydraulic oil tank through the unloading valve and the oil return oil way to realize the low-pressure unloading.
The multi-way valve is provided with a PS control oil way which sequentially flows through a first main valve middle oil way and a second main valve middle oil way, a PS oil inlet of the PS control oil way is connected with a variable pressure oil source, and a PS oil outlet is connected with a hydraulic control end of the unloading valve. When the first main joint valve and the second main joint valve are both in the middle position, the PS control oil path is communicated by the first main joint valve and the second main joint valve, and a pressure signal from a variable pressure oil source acts on a hydraulic control end of the unloading valve through the PS control oil path, so that the quantitative pressure oil source is unloaded through the unloading valve.
The system also comprises an adjustable overflow valve with adjustable overflow pressure; two ends of the adjustable overflow valve are respectively connected with a quantitative pressure oil source and a hydraulic oil tank, and the overflow opening pressure of the adjustable overflow valve is slightly lower than the unloading opening preset unloading pressure of the unloading valve group. When the quantitative pressure oil source supplies oil for the first hydraulic actuating part independently, the first hydraulic actuating part overflows through the adjustable overflow valve along with the rising of the load, the unloading valve is not opened, the phenomenon that the pressure rises repeatedly and falls is avoided, the flow change is stable, different overflow pressures are set through the adjustable overflow valve, and the first hydraulic actuating part is suitable for different working conditions.
In the above constant variable quantity flow dividing and converging system, the adjustable overflow valve is an electric proportional overflow valve.
In the above constant-variable flow dividing and merging hydraulic control system, the system further comprises an LS overflow valve, an oil inlet end of the LS overflow valve is communicated with a load feedback oil port of the second joint main valve, and an oil outlet end of the LS overflow valve is communicated with an oil return line.
In the constant and variable flow dividing and merging hydraulic system, a main safety valve is arranged between an oil inlet and an oil return circuit of a first main connecting valve in the multi-way valve.
In the constant-variable flow dividing and merging hydraulic control system, a first shuttle valve is arranged in the multi-way valve, two oil inlet ends of the first shuttle valve are respectively connected with a load feedback output port of a first main valve and a load feedback output port of a second main valve, and an oil outlet end of the first shuttle valve is used for being connected with a load feedback input port of a variable pressure oil source.
In the above-mentioned constant-variable flow-dividing and converging hydraulic control system, the variable pressure oil source includes a variable pump having an oil suction port connected to the hydraulic oil tank, and a flow amplifying valve connected to the variable pump, an EF oil port of the flow amplifying valve is connected to an oil inlet of the first united main valve, and a PS oil inlet is connected to a pump port of the variable pump.
In the above-mentioned constant-variable flow-dividing and converging hydraulic control system, the variable pressure oil source further includes a second shuttle valve, two oil inlet ends of the second shuttle valve are respectively connected with the load feedback output port of the flow amplifying valve and the oil outlet end of the first shuttle valve, and the oil outlet end of the second shuttle valve is connected with the load feedback input port of the variable pump. Furthermore, the oil outlet end of the second shuttle valve is connected with the load feedback input port of the variable displacement pump through a one-way damping valve.
The technical scheme for realizing the purpose of the utility model is as follows: a loader is constructed, and is characterized by comprising the constant variable flow-dividing and flow-dividing hydraulic control system, wherein a first hydraulic actuator is a movable arm oil cylinder, and a second hydraulic actuator is a rotating bucket oil cylinder.
Compared with the prior art, in the utility model, when a quantitative pressure oil source independently supplies oil for the first hydraulic actuating element, the first hydraulic actuating element overflows through the adjustable overflow valve along with the rise of the load, the unloading valve is not opened, the phenomenon that the pressure rises and falls repeatedly is avoided, and the flow change is stable.
Drawings
Fig. 1 is a schematic diagram of a fixed variable flow/confluence hydraulic control system of a loader according to the present invention.
Fig. 2 is a schematic diagram of an unloading valve group in the constant variable quantity flow dividing and combining hydraulic control system.
Part names and serial numbers in the figure:
the hydraulic control system comprises a hydraulic oil tank 1, a fixed displacement pump 2, an adjustable overflow valve 3, a variable displacement pump 4, a one-way damping valve 5, a second shuttle valve 6, a flow amplifying valve 7, an unloading valve group 8, a multi-way valve 9, a first main joint valve 91, a second main joint valve 92, a safety valve 93, an oil return oil path 94, a first shuttle valve 95, a PS control oil path 96, a rotary bucket oil cylinder 10, a movable arm oil cylinder 11 and an electric proportion LS overflow valve 12.
Detailed Description
The following description of the embodiments refers to the accompanying drawings.
The main part of the hydraulic control system of the loader in this embodiment is shown in fig. 1, and it mainly includes a hydraulic oil tank 1, a fixed displacement pump 2, a variable displacement pump 4, a flow amplification valve 7, a multi-way valve 9, an unloading valve group 8, a first hydraulic actuator 11, a second hydraulic actuator 10, and the like.
As shown in fig. 2, the unloading valve group 8 includes a check valve 81, an unloading valve 83, and an unloading opening valve 82; the oil inlet and outlet ends of the check valve 81 are respectively connected with an oil inlet P1 and an oil outlet P4 of the unloading valve group; the oil inlet and outlet ends of the unloading valve 83 are respectively connected with an oil inlet P1 and an unloading port T1 of the unloading valve group; the oil inlet and outlet ends of the unloading opening valve 82 are respectively connected with the oil outlet end of the one-way valve 81 and the hydraulic control end of the unloading valve 83. The unloading opening valve 82 is used for setting the opening pressure of the unloading valve 83, when the pressure at the oil outlet P4 of the unloading valve group 8 is greater than the pressure set by the unloading opening valve 82, the unloading opening valve 82 is opened to transmit the pressure to the hydraulic control end of the unloading valve 83, so that the unloading valve 83 is opened, the hydraulic control end of the unloading valve 83 can be opened only by relatively small pressure to realize unloading, and relatively speaking, the unloading opening valve 82 is opened only by relatively large pressure.
As shown in fig. 1, the multi-way valve 9 mainly includes a first main branch valve 91 (i.e., a boom main branch valve), a second main branch valve 92 (i.e., a dump main branch valve), a first shuttle valve 95, a safety valve 93, and the like. The first and second joint main valves 91 and 92 are provided with merging oil paths with middle positions communicated, that is, when at least one of the first and second joint main valves 91 and 92 is at the middle position, the oil inlet P3 of the first joint main valve 91 and the oil inlet P2 of the second joint main valve 92 are communicated with each other, when the first and second joint main valves 91 and 92 are at the direction change position, the merging oil paths are closed, and the oil inlet 93 of the first joint main valve and the oil inlet P2 of the second joint main valve are not communicated with each other.
Two ends of the safety valve 93 are respectively communicated with an oil inlet P3 of the first joint main valve and an oil return path 94, and the safety valve is used for controlling the maximum load pressure on a connecting oil path of the boom cylinder. The maximum safety pressure of the boom linkage path is set by setting the opening pressure of the safety valve 93, and the system pressure of the boom linkage path, which is higher than the turning bucket linkage, can be set by adjusting the pressure of the shut-off valve in the variable pump 4.
The oil inlet end of the first shuttle valve 95 is respectively communicated with the load feedback output ports of the first joint main valve 91 and the second joint main valve 92, and the load pressure output by the load feedback output port of the first joint main valve is compared with the load pressure output by the load feedback output port of the second joint main valve and then output by the oil outlet end of the first shuttle valve 95. The oil inlet end of the electric proportional LS overflow valve 12 is communicated with the load feedback oil port of the second joint main valve 92, the oil outlet end of the electric proportional LS overflow valve 12 is communicated with the oil return oil path 94, and different system pressures of the rotary bucket joint are set by adjusting the electric proportional LS overflow valve 12. And an oil return path 94 of the multi-way valve 9 is communicated with the hydraulic oil tank through a pipeline to realize oil return of the hydraulic control system.
The multi-way valve 9 is provided with a PS control oil path 96 which sequentially flows through a first main valve middle oil path and a second main valve middle oil path, a PS oil inlet of the PS control oil path 96 is connected with a variable pressure oil source, and a PS oil outlet is connected with a hydraulic control end of the unloading valve 83. When both the first and second main valves 91 and 92 are in the neutral position, the PS pilot oil path 96 is opened by the first and second main valves 91 and 92, and a pressure signal from the variable pressure oil source acts on the pilot end of the unloading valve 83 via the PS pilot oil path 96 to open the unloading valve 83, so that the pressure oil from the constant pressure oil source is unloaded by the unloading valve 83. When one of the first and second joint main valves 91 and 92 is at the switch position but not at the neutral position (i.e., bucket retraction or boom raising and lowering operations are performed), the PS control oil path 96 is closed, and the unloading valve 83 cannot be unloaded by a pressure signal from the variable pressure oil source through the PS control oil path 96.
The working oil port P3 of the first joint main valve is connected to the first hydraulic actuator 11 (i.e., a boom cylinder), and controls the first hydraulic actuator 11 to extend and contract to lift a boom. The working oil port of the second linkage main valve 92 is connected with the second hydraulic actuator 10 (namely, a rotating bucket cylinder), and controls the second hydraulic actuator 10 to extend and retract so as to realize the bucket folding and unfolding. The pilot-controlled ends of the first and second main valves 91 and 92 are connected to a pilot valve (not shown), and an operator controls the pilot valve to realize control of a multi-way valve, thereby realizing bucket retraction and boom raising and lowering operations.
The fixed displacement pump 2 is a gear pump and is used as a fixed-displacement pressure oil source, an oil suction port of the fixed displacement pump is connected with the hydraulic oil tank 1, a pump port is connected with an oil inlet P1 of the unloading valve bank 8, an oil outlet P4 of the unloading valve bank is connected with an oil inlet P2 of a second main valve in the multi-way valve 9, and an unloading port T1 of the unloading valve bank 8 is connected with the hydraulic oil tank 1 through an oil return path 94.
The variable pressure oil source comprises a variable pump 4 (such as a plunger pump) and a flow amplifying valve 7. The variable pump 4 is connected with the oil suction port and the hydraulic oil tank 1, and the pump port is connected with the flow amplifying valve 7. The variable pressure oil source is also used as a pressure oil source of a loader steering system, and hydraulic elements (not shown in the figure) such as a steering gear, a steering oil cylinder and the like of the steering system are connected with the flow amplifying valve 7. And a PS oil inlet of the PS control oil path 96 is connected with a pump port of the variable displacement pump 4.
The CF oil port of the flow amplifying valve 7 is connected with a steering hydraulic system, and the EF oil port of the flow amplifying valve is communicated with an oil inlet P3 of a first joint main valve of the multi-way valve 9. The priority valve in the flow amplifying valve 7 preferentially supplies oil to the steering system through the CF oil port, and the surplus flow is output from the EF oil port of the priority valve in the flow amplifying valve 7 to supply oil to the working device.
The LS port (load feedback output port) of the flow amplifying valve 7 is connected to one oil inlet end of the second shuttle valve 6, the other oil inlet end of the second shuttle valve 6 is connected to the oil outlet end of the first shuttle valve 95, and the oil outlet end of the second shuttle valve 6 is connected to the load feedback input port of the variable displacement pump 4. The first and second shuttle valves 95 and 6 compare the bucket load, the boom load, and the steering load, and transmit the maximum load signal to the variable displacement pump 4 to output the flow rate as required.
The adjustable overflow valve 3 is an electric proportional overflow valve, two ends of the adjustable overflow valve 3 are respectively connected with a quantitative pressure oil source (quantitative pump 2) and a hydraulic oil tank, and the overflow opening pressure of the adjustable overflow valve is slightly lower than the unloading opening preset unloading pressure of the unloading valve group. When the metering pump 2 independently supplies oil for the first hydraulic actuating part 11, the first hydraulic actuating part is overflowed by the adjustable overflow valve 3 along with the rising of the load, the unloading valve 83 is not opened, the phenomenon that the pressure rises repeatedly and falls is avoided, the flow change is stable, different overflow pressures are set through the adjustable overflow valve, and the metering pump adapts to different working conditions.
In this embodiment, when the bucket is not being retracted and the boom is being raised and lowered, the first joint main valve 91 and the second joint main valve 92 in the multi-way valve 9 are both in the neutral position, the PS control oil path 96 takes oil from the oil outlet of the variable displacement pump 4 and acts on the hydraulic control end of the unloading valve 83 to open the unloading valve 83, and the pressure oil output by the fixed displacement pump 2 is unloaded to the oil tank by the unloading valve 83 at a low pressure.
When the whole machine is in single action, namely only the single action of lifting a movable arm or only the single action of retracting and releasing a bucket, the main valve of one of the first main valve 91 and the second main valve 92 in the multi-way valve 9 is in the middle position, oil of the variable pump 4 and the fixed displacement pump 2 is converged and enters a movable arm cylinder or a rotating bucket cylinder, when the load is gradually increased, the pressure of an oil inlet of the multi-way valve 9 (the pressure of a port P2 or a port P3, the two oil ports are communicated due to confluence, and the pressure is equal) reaches the opening pressure of the unloading opening valve 82, the unloading opening valve 82 transmits the pressure to the opening end of the unloading valve 83, so that the unloading valve 83 is opened to enable the oil coming from the fixed displacement pump to enter a hydraulic oil tank through the unloading valve, and the unloading of the fixed displacement pump pressure oil is achieved. The pressure oil from the oil inlet P3 of the first joint main valve makes the oil outlet of the unloading valve group 8 (i.e. the oil inlet P2 of the second joint main valve) continuously have pressure to act on the hydraulic control end of the unloading valve through the unloading opening valve 82, so that the unloading valve 83 is in an opening state. Therefore, even if the pressure of the oil inlet P1 of the unloading valve group 8 suddenly drops due to the opening and unloading of the unloading valve, the unloading valve 83 is still kept open, and the unloading valve is prevented from being opened and closed frequently, so that the system pressure is stable. After the unloading valve is opened, the variable pump provides pressure oil alone.
When the combined operation is performed, that is, when the boom raising and lowering operation and the bucket retracting operation are performed simultaneously, the first interlocking main valve 91 and the second interlocking main valve 92 of the multi-way valve 9 are not positioned at the neutral positions, the oil liquid of the fixed displacement pump 2 enters the swing bucket cylinder only through the second interlocking main valve 92 of the multi-way valve, and the oil liquid of the variable displacement pump 4 enters the boom cylinder only through the first interlocking main valve of the multi-way valve. The first joint main valve oil inlet P3 and the second joint main valve oil inlet P2 in the multi-way valve cannot be communicated. When the load of the rotating bucket joint is increased, the oil pressure of the oil inlet P2 of the second main valve joint reaches the opening pressure of the electric proportional overflow valve 3, the oil of the fixed displacement pump overflows from the electric proportional overflow valve, the pressure of the oil inlet P1 of the unloading valve group 8 does not rise any more, the unloading opening valve 82 and the unloading valve in the unloading valve group 8 cannot be opened, the phenomenon that the pressure rises and falls repeatedly is avoided, and the flow change is stable. Different relief pressures are set by the electric proportional relief valve 4.
Claims (9)
1. A constant-variable flow dividing and merging hydraulic control system comprises a variable pressure oil source, a fixed pressure oil source, a multi-way valve, a first hydraulic actuating element, a second hydraulic actuating element, an unloading valve group and a hydraulic oil tank, wherein the multi-way valve comprises a first joint main valve for controlling the first hydraulic actuating element and a second joint main valve for controlling the second hydraulic actuating element; two confluence oil paths which respectively pass through a first main valve middle oil path and a second main valve middle oil path are arranged between the first main valve oil inlet and the second main valve oil inlet; the system is characterized by also comprising an adjustable overflow valve with adjustable overflow pressure;
the unloading valve group comprises a one-way valve, an unloading valve and an unloading opening valve; the oil inlet and outlet ends of the one-way valve are respectively connected with an oil inlet and an oil outlet of the unloading valve group; the oil inlet and outlet ends of the unloading valve are respectively connected with an oil inlet and an unloading port of the unloading valve group; the oil inlet end and the oil outlet end of the unloading opening valve are respectively connected with the oil outlet end of the one-way valve and the hydraulic control end of the unloading valve, and when the pressure of the oil inlet end of the unloading opening valve is higher than the preset unloading pressure, the oil outlet end outputs the preset pressure for opening the unloading valve;
the quantitative pressure oil source is connected with an oil inlet of the unloading valve bank, and an oil outlet of the unloading valve bank is connected with an oil inlet of the second main valve; the unloading port of the unloading valve group is communicated with an oil return oil way communicated with the hydraulic oil tank;
a PS control oil way which sequentially flows through a first main valve middle position oil way and a second main valve middle position oil way is arranged in the multi-way valve, a PS oil inlet of the PS control oil way is connected with a variable pressure oil source, and a PS oil outlet is connected with a hydraulic control end of an unloading valve;
two ends of the adjustable overflow valve are respectively connected with a quantitative pressure oil source and a hydraulic oil tank, and the overflow opening pressure of the adjustable overflow valve is slightly lower than the unloading opening preset unloading pressure of the unloading valve group.
2. The constant-variable flow dividing and combining hydraulic control system according to claim 1, wherein the adjustable overflow valve is an electric proportional overflow valve.
3. The constant-variable flow dividing and combining and converging system according to claim 1, characterized by further comprising an LS overflow valve, wherein an oil inlet end of the LS overflow valve is communicated with a load feedback oil port of the second joint main valve, and an oil outlet end of the LS overflow valve is communicated with an oil return line.
4. The constant-variable flow dividing and combining and converging hydraulic system according to claim 1, wherein a main safety valve is arranged between an oil inlet and an oil return line of a first joint main valve in the multi-way valve.
5. The constant-variable flow dividing and combining liquid control system according to any one of claims 1 to 4, wherein a first shuttle valve is arranged in the multi-way valve, two oil inlet ends of the first shuttle valve are respectively connected with the load feedback output ports of a first joint main valve and a second joint main valve, and an oil outlet end of the first shuttle valve is used for being connected with the load feedback input port of a variable pressure oil source.
6. The constant-variable flow dividing and combining and converging system according to claim 5, wherein the variable pressure oil source comprises a variable pump with an oil suction port connected with the hydraulic oil tank and a flow amplifying valve connected with the variable pump, an EF oil port of the flow amplifying valve is connected with an oil inlet of the first united main valve, and a PS oil inlet is connected with a pump port of the variable pump.
7. The constant-variable flow dividing and combining hydraulic control system according to claim 6, wherein the variable pressure oil source further comprises a second shuttle valve, two oil inlet ends of the second shuttle valve are respectively connected with the load feedback output port of the flow amplifying valve and the oil outlet end of the first shuttle valve, and the oil outlet end of the second shuttle valve is connected with the load feedback input port of the variable pump.
8. The constant-variable flow dividing and combining hydraulic control system according to claim 7, wherein the oil outlet end of the second shuttle valve is connected with the load feedback input port of the variable pump through a one-way damping valve.
9. A loader characterized by having a constant variable converging-diverging fluid control system according to any one of claims 1 to 8.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121443223.7U CN215927958U (en) | 2021-06-28 | 2021-06-28 | Constant-variable flow-dividing and flow-dividing hydraulic control system and loader |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202121443223.7U CN215927958U (en) | 2021-06-28 | 2021-06-28 | Constant-variable flow-dividing and flow-dividing hydraulic control system and loader |
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| CN215927958U true CN215927958U (en) | 2022-03-01 |
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| CN202121443223.7U Active CN215927958U (en) | 2021-06-28 | 2021-06-28 | Constant-variable flow-dividing and flow-dividing hydraulic control system and loader |
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2021
- 2021-06-28 CN CN202121443223.7U patent/CN215927958U/en active Active
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