CN113757200B - Hydraulic system, engineering machinery and control method of hydraulic system - Google Patents
Hydraulic system, engineering machinery and control method of hydraulic system Download PDFInfo
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- CN113757200B CN113757200B CN202111015781.8A CN202111015781A CN113757200B CN 113757200 B CN113757200 B CN 113757200B CN 202111015781 A CN202111015781 A CN 202111015781A CN 113757200 B CN113757200 B CN 113757200B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/08—Servomotor systems without provision for follow-up action; Circuits therefor with only one servomotor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/025—Pressure reducing valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B19/00—Testing; Calibrating; Fault detection or monitoring; Simulation or modelling of fluid-pressure systems or apparatus not otherwise provided for
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B21/00—Common features of fluid actuator systems; Fluid-pressure actuator systems or details thereof, not covered by any other group of this subclass
- F15B21/08—Servomotor systems incorporating electrically operated control means
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- General Engineering & Computer Science (AREA)
- Fluid-Pressure Circuits (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
Abstract
The embodiment of the invention provides a hydraulic system, engineering machinery and a control method thereof, wherein the hydraulic system comprises the following components: the system comprises a hydraulic oil tank, an electric proportional pump, a multi-way valve assembly, a main oil supply pipeline, a bypass overflow pipeline, a detection device and a controller; the detection device is used for detecting the unit flow overflowed by the three-way flow valve or the pressure on a bypass overflow pipe positioned behind the three-way flow valve; the controller is respectively electrically connected with the electric proportional pump, the multi-path working unit and the detection device, and controls the electric proportional pump according to the detection result of the detection device. According to the hydraulic system provided by the invention, the three-way flow valve is used for introducing a feedback mechanism, detecting the state of oil flowing through the bypass overflow pipeline in real time, and controlling the flow of the electric proportional pump according to the detection result so as to meet the system requirement value and have a small amount of surplus, and the flow is matched with the system requirement by using the least heating value. In addition, in the control mode, all mechanisms in the hydraulic system are in a pressure standby state at any time, so that the response speed of the hydraulic system is effectively improved.
Description
Technical Field
The invention relates to the field of hydraulic pressure, in particular to a hydraulic system, engineering machinery and a control method thereof.
Background
Currently, the arm support multi-way valve of the concrete pump truck has two types, namely PSL and PSV. The PSV multiway valve is matched with a load sensitive variable pump and is generally used for a long-arm frame pump truck. The PSL multiplex valve typically matches a fixed displacement pump for a short arm frame pump truck. Because the PSV multiway valve does not respond fast to the load sensitive variable pump flow regulation response characteristic with the electric proportioning pump, the electric proportioning pump is now being popularized on long-arm pump trucks to match the PSL multiway valve configuration.
The displacement of the electric proportional pump needs to be adjusted when the electric proportional pump is matched with the PSL multi-way valve, and the requirements of the arm support multi-way valve are met at any time. If the oil supply of the oil pump is too small, the boom can be retracted and unfolded slowly, and if the oil supply of the oil pump is too large, the system overflows and heats.
The existing regulating method mainly converts the current value (given by a remote controller) of each linkage proportional valve of the arm support multi-way valve into the flow demand of each linkage valve core. And feeding back the flow requirement of each link to the controller, and summing to obtain the total flow required by the arm support multi-way valve. And outputting proper current to the electric proportional oil pump by the controller according to the corresponding relation between the control current value and the displacement of the electric proportional oil pump, so that the oil pump supplies proper flow to the arm support multi-way valve. However, the current value and the valve core opening degree of the arm support multi-way valve are not consistent, and the current value and the flow cannot be in one-to-one correspondence. The error between the actual demand flow and the calculated flow of the arm support multi-way valve is larger. The current value of the electric proportional oil pump and the displacement of the oil pump are not completely in linear relation, and the flow error output by the oil pump is larger through the given oil pump current value, so that the oil pump is excessively large in flow and the system is heated, or the boom with excessively small oil pump flow acts slowly.
Disclosure of Invention
The embodiment of the invention provides a hydraulic system, engineering machinery and a control method thereof, which are used for solving the problems that the actual demand flow, calculated flow and output flow errors of a multi-way valve of an arm support of the existing hydraulic system are large, so that the system heats due to the overlarge flow of an oil pump or the action of the arm support with the overlarge flow of the oil pump is slow.
An embodiment of the present invention provides a hydraulic system including:
a hydraulic oil tank;
the oil inlet of the electric proportional pump is communicated with the hydraulic oil tank;
the oil inlets of the main oil supply pipeline and the bypass overflow pipeline are respectively connected with the oil outlets of the electric proportional pumps, and the oil outlets of the bypass overflow pipeline are connected with the hydraulic oil tank;
the multi-way valve assembly comprises a multi-way working link and a three-way flow valve, the multi-way working link is respectively communicated with the main oil supply pipeline, and the three-way flow valve is connected in series on a bypass overflow pipeline;
detecting means for detecting a unit flow rate overflowed from the three-way flow valve or a pressure on the bypass overflow pipe located after the three-way flow valve;
and the controller is respectively and electrically connected with the electric proportional pump, the multi-path working unit and the detection device, and controls the electric proportional pump according to the detection result of the detection device.
According to the hydraulic system of the embodiment of the invention, a damping hole is arranged on the bypass overflow pipe behind the three-way flow valve, and the detection device is a pressure detection device which is used for detecting the pressure on the pipeline between the damping hole and the three-way flow valve.
According to the hydraulic system of one embodiment of the invention, the detection device is a flow detection device, and the flow detection device is used for detecting the unit flow of the three-way flow valve.
According to the hydraulic system of the embodiment of the invention, a damping hole is arranged on the bypass overflow pipe behind the three-way flow valve, and two ends of the damping hole are connected with the bypass overflow valve in parallel.
According to the hydraulic system of one embodiment of the invention, a bypass electromagnetic valve is arranged in the bypass overflow pipeline, and a spring cavity of the three-way flow valve is communicated with an oil return spring cavity of each working link through the bypass electromagnetic valve so as to be communicated with the hydraulic oil tank.
According to a hydraulic system of one embodiment of the present invention, the hydraulic system further includes: the main overflow valve, the pilot filter and the pilot pressure reducing valve;
an oil inlet of the main overflow valve is communicated with an oil outlet of the electric proportional pump, and an oil outlet of the main overflow valve is communicated with the hydraulic oil tank; the oil inlet of the pilot relief valve is connected to a pipeline between the oil inlet of the main overflow valve and the oil outlet of the electric proportional pump through the pilot filter, the oil outlet of the pilot relief valve is communicated with the oil inlet spring cavity of the multi-path working unit, and the oil return port of the pilot relief valve is communicated with the hydraulic oil tank.
According to a hydraulic system of one embodiment of the present invention, the hydraulic system further includes: an oil absorption filter and a high pressure filter; an oil inlet of the electric proportional pump is connected with the hydraulic oil tank through the oil suction filter; and an oil outlet of the electric proportional pump is connected with the high-pressure filter.
The embodiment of the invention also provides a control method of the hydraulic system, which comprises the following steps:
predicting total flow requirements required by all working units according to the current of each working unit, and controlling the opening of the electric proportional pump according to the total flow requirements;
detecting unit flow overflowed by a three-way flow valve of the bypass overflow pipeline or a pressure value on the bypass overflow pipeline after the three-way flow valve;
and adjusting the opening degree of the electric proportional pump according to the unit flow or the pressure value.
According to the control method of the hydraulic system of one embodiment of the invention, the specific step of adjusting the opening degree of the electric proportional pump according to the unit flow rate or the pressure value comprises the following steps:
judging whether the unit flow or pressure value is in a preset range or not;
if the unit flow or the pressure value is judged to reach the upper threshold value, controlling to reduce the opening of the electric proportional pump; and if the unit flow or the pressure value reaches the lower threshold value, controlling to increase the opening of the electric proportional pump.
The hydraulic system, the engineering machinery and the control method thereof provided by the embodiment of the invention are provided with a hydraulic oil tank, an electric proportional pump, a multi-way valve assembly, a main oil supply pipeline, a bypass overflow pipeline, a detection device and a controller, a feedback mechanism is introduced by using a three-way flow valve, the oil liquid state flowing through the bypass overflow pipeline is detected in real time, and the flow of the electric proportional pump is controlled according to the detection result, so that the system requirement value is met, a small amount of surplus exists, and the flow is matched with the system requirement by using the minimum heating value. In addition, by the control mode, all mechanisms in the hydraulic system are in a pressure standby state at any time, so that the response speed of the hydraulic system can be effectively improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a hydraulic system according to an embodiment of the present invention;
FIG. 2 is a flow chart of a method of controlling a hydraulic system according to an embodiment of the present invention;
reference numerals:
1. a hydraulic oil tank; 11. A high pressure filter; 12. An electric proportional pump;
13. an oil absorption filter; 2. A main oil supply line; 21. A main overflow valve;
22. a pilot filter; 23. A pilot pressure reducing valve; 3. A bypass overflow line;
31. a three-way flow valve; 32. A pressure detection device; 33. A damping hole;
34. a bypass overflow valve; 35. A bypass solenoid valve; 4. A first work linkage;
5. a second work linkage; 6. A back pressure valve.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
An embodiment of the present invention proposes a hydraulic system, as shown in fig. 1, including: the hydraulic oil tank 1, the electric proportioning pump 12, the main oil supply pipeline 2, the bypass overflow pipeline 3, the multi-way valve assembly, the detection device and the controller.
The hydraulic oil tank 1 is used for supplying oil to a hydraulic system and is provided with an oil outlet and an oil return port. The oil inlet of the electric proportional pump 12 is communicated with the hydraulic oil tank 1; the oil inlets of the main oil supply pipeline 2 and the bypass overflow pipeline 3 are respectively connected with the oil outlets of the electric proportional pump 12, and the oil outlets of the bypass overflow pipeline 3 are connected with the hydraulic oil tank 1; the multi-way valve assembly comprises a multi-way working link and a three-way flow valve 31, wherein the multi-way working link is respectively communicated with the main oil supply pipeline 2, and the three-way flow valve 31 is connected in series on the bypass overflow pipeline 3; the detection device is used for detecting the unit flow overflowed by the three-way flow valve 31 or the pressure on the bypass overflow pipeline 3 positioned behind the three-way flow valve 31. The three-way flow valve 31 is used for guiding the surplus oil back to the hydraulic oil tank 1 when the flow rate in the oil path exceeds the actual demand flow rate of the multi-way working link. The controller is respectively and electrically connected with the electric proportioning pump 12, the multi-path working unit and the detection device, and controls the electric proportioning pump 12 according to the detection result of the detection device.
In this embodiment, as shown in fig. 1, when the hydraulic system works, the controller predicts the total flow requirement required by all working units according to the current of each working unit, and controls the electric proportional pump 12 according to the total flow requirement, and gives the electric proportional pump 12 a preliminary current value, so that the flow provided by the electric proportional pump 12 can be quickly matched to the vicinity of the requirement value of the hydraulic system. Then the oil flowing through the bypass overflow pipe 3 is detected, and the electric proportional pump 12 is finely adjusted according to the detected unit flow or pressure value.
For example, if the detection device detects that the back pressure value is 0 or less than the lower limit of the preset range, it is considered that no excessive flow of the electric proportional pump 12 overflows from the three-way flow valve 31, and at this time, the controller increases the current of the electric proportional pump 12 and increases the output of the oil until the three-way flow valve 31 has a certain excessive flow (the back pressure value generated by detecting the overflow flow of the three-way flow valve is determined). If the back pressure value generated by the surplus flow of the three-way flow valve 31 is detected to be too high and exceeds the upper limit of the preset range, the flow supplied by the electric proportional pump 12 is considered to be too high and exceeds the system requirement, and at the moment, the controller adjusts the current of the electric proportional pump 12 to be small and reduces the flow output of the electric proportional pump 12. Thus, the flow rate of the electric proportional pump 12 is controlled to meet the requirement value of the system and a small amount of margin is provided, so that the electric proportional pump 12 can be matched with the requirement of the system with the least heating value. In addition, in the control mode, the electric proportional pump 12 is in a pressure standby state at any time, so that the response speed of the hydraulic system can be effectively improved.
The hydraulic system provided by the embodiment of the invention is provided with a hydraulic oil tank, an electric proportional pump, a multi-way valve assembly, a main oil supply pipeline, a bypass overflow pipeline, a detection device and a controller, wherein a feedback mechanism is introduced by using a three-way flow valve, the state of oil flowing through the bypass overflow pipeline 3 is detected in real time, and the flow of the electric proportional pump 12 is controlled according to the detection result, so that the system requirement value is met, a small amount of surplus exists, and the flow is matched with the system requirement by using the minimum heating value. In addition, by the control mode, all mechanisms in the hydraulic system are in a pressure standby state at any time, so that the response speed of the hydraulic system can be effectively improved.
As shown in fig. 1, a damping hole 33 is provided on the bypass overflow pipe 3 behind the three-way flow valve 31, the detecting device is a pressure detecting device 32, and the pressure detecting device 32 is used for detecting the pressure on the pipe between the damping hole 33 and the three-way flow valve 31.
At this time, the pressure detecting device 32 monitors the pressure at the front end of the damping hole in real time, and if the back pressure value detected by the pressure detecting device 32 is 0 or less than the lower limit of the preset range, it is considered that no excessive flow of the electric proportional pump 12 overflows from the three-way flow valve 31, and at this time, the electric proportional pump 12 is increased in current, so that the output of the oil is increased until the three-way flow valve 31 has a certain excessive flow (the back pressure value generated by detecting the overflow flow of the three-way flow valve is determined). If the back pressure value generated by the surplus flow of the three-way flow valve 31 is detected to be too high and exceeds the upper limit of the preset range, the flow supplied by the electric proportional pump 12 is considered to be too high and exceeds the system requirement, and at the moment, the current of the electric proportional pump 12 is adjusted to be small, so that the flow output of the electric proportional pump 12 is reduced. Thus, the flow rate of the electric proportional pump 12 is controlled to meet the requirement value of the system and a small amount of margin is provided, so that the electric proportional pump 12 can be matched with the requirement of the system with the least heating value.
Alternatively, in other embodiments of the present application, the detection device is a flow detection device for detecting a unit flow rate of the three-way flow valve 31. The variation of the unit flow is used to control the operation of the hydraulic system.
Meanwhile, a bypass overflow valve 34 can be connected in parallel at two ends of the damping hole 33. The bypass relief valve 34 is used to define the highest pressure at the front end of the orifice 33 to ensure that the three-way flow valve 31 will normally vent even in the event of a failure of the detection device or system.
For convenient installation, the detection device and the damping hole 33 can be embedded into the three-way flow valve 31 during actual installation.
As shown in fig. 1, a bypass solenoid valve 35 is provided in the bypass relief line 3, and the spring chamber of the three-way flow valve 31 communicates with the return spring chamber of each working unit via the bypass solenoid valve 35, and further communicates with the hydraulic tank 1.
For example, in the present embodiment, a first work order 4 and a second work order 5 are provided. The first working link 4 and the second working link 5 are both used for controlling the arm support to act. The spring chamber of the three-way flow valve 31 is simultaneously communicated with the oil return spring chamber of the first working unit 4 and the oil return spring chamber of the second working unit 5 through the bypass electromagnetic valve 35, and is further communicated with the hydraulic oil tank 1.
When the first working unit 4 and the second working unit 5 are operated, the electric proportion and the flow characteristic of each unit are firstly obtained, the total flow required by the working unit is estimated approximately, then the electric proportion pump 12 is given a preliminary current value according to the electric proportion flow characteristic of the electric proportion pump 12, so that the flow provided by the electric proportion pump 12 can be quickly matched to the vicinity of the demand value of the system, then the current of the electric proportion pump 12 is finely adjusted according to the pressure value of the front end of the damping hole 33 on the oil return path of the three-way flow valve, the flow of the electric proportion pump 12 is corrected, and the problem that the system is heated due to excessive surplus flow of the electric proportion pump 12 or the boom is too slow due to too little flow provided by the oil pump is avoided. The oil flowing through the first working link 4 and the second working link 5 finally flows back to the hydraulic oil tank 1 through the back pressure valve 6 from the oil return ends of the working links.
In this embodiment, the hydraulic system further includes: a main relief valve 21, a pilot filter 22 and a pilot relief valve 23.
Wherein, the oil inlet of the main overflow valve 21 is communicated with the oil outlet of the electric proportional pump 11, the oil outlet of the main overflow valve 21 is communicated with the hydraulic oil tank 1, and the main overflow valve 21 is used for guiding oil back to the hydraulic oil tank 1 when the pressure in the oil path exceeds a preset value, for example, when the pressure exceeds 37 MPA. An oil inlet of the pilot relief valve 23 is connected to a pipeline between an oil inlet of the main overflow valve 21 and an oil outlet of the electric proportional pump 11 through a pilot filter 22, the oil outlet of the pilot relief valve 23 is communicated with an oil inlet spring cavity of the multi-path working link, and an oil return port of the pilot relief valve 23 is communicated with the hydraulic oil tank 1. The pilot filter 22 is used for filtering oil, and the pilot relief valve 23 is used for adjusting the pressure of the filtered oil to avoid the excessive pressure in the control oil path.
In the working process, the electric proportional pump 12 guides the oil in the hydraulic oil tank 1 into the oil inlet spring cavity of the multi-path working unit through the pilot filter 22 and the pilot pressure reducing valve 23, so that the opening degree of valve cores of all the working units is adjusted, the oil entering the multi-path working unit can enter the arm support oil cylinder, and the action of the arm support is adjusted.
As shown in fig. 1, the filter is provided with two, an oil suction filter 13 and a high pressure filter 11, respectively. The oil inlet of the electric proportional pump 12 is connected with the hydraulic oil tank 1 through an oil suction filter 13; the oil outlet of the electric proportioning pump 12 is connected with the high-pressure filter 11.
The oil suction filter 13 is used for protecting the electric proportioning pump 12 and other hydraulic components so as to avoid sucking in pollution impurities and effectively control the cleanliness of the hydraulic system. The high-pressure filter 11 is used to filter impurities in a high-pressure environment.
In the working process, the electric proportional pump 12 guides the oil in the hydraulic oil tank 1 into the oil suction filter 13 through the oil outlet and then enters the oil pump, and the oil boosted by the oil pump is filtered by the high-pressure filter and enters the system.
The invention also provides engineering machinery, such as a pump truck or a crane and other engineering vehicles. As shown in fig. 1, the construction machine includes the hydraulic system described above. The specific structure can be described with reference to fig. 1, and is not described herein.
When the engineering machinery works, the controller predicts total flow requirements required by all working units according to the current of each working unit, and controls the electric proportional pump 12 according to the total flow requirements to supply the electric proportional pump 12 with a preliminary current value, so that the flow provided by the electric proportional pump 12 can be quickly matched to the vicinity of the requirement value of the hydraulic system. Then the oil flowing through the bypass overflow pipe 3 is detected, and the electric proportional pump 12 is finely adjusted according to the detected unit flow or pressure value. If the back pressure value detected by the detection device is 0 or less than the lower limit of the preset range, it is considered that no excessive flow of the electric proportional pump 12 overflows from the three-way flow valve 31, and at this time, the electric proportional pump 12 current is increased to increase the output of the oil until the three-way flow valve 31 has a certain excessive flow (the back pressure value generated by the overflow flow of the three-way flow valve is detected to determine). If the back pressure value generated by the surplus flow of the three-way flow valve 31 is detected to be too high and exceeds the upper limit of the preset range, the flow supplied by the electric proportional pump 12 is considered to be too high and exceeds the system requirement, and at the moment, the current of the electric proportional pump 12 is adjusted to be small, so that the flow output of the electric proportional pump 12 is reduced. Thus, the flow rate of the electric proportional pump 12 is controlled to meet the requirement value of the system and a small amount of margin is provided, so that the electric proportional pump 12 can be matched with the requirement of the system with the least heating value. In addition, in the control mode, the electric proportional pump 12 is in a pressure standby state at any time, so that the response speed of the hydraulic system can be effectively improved.
The engineering machinery provided by the embodiment of the invention is provided with the hydraulic system, a feedback mechanism is introduced by utilizing a three-way flow valve, the oil liquid state flowing through the bypass overflow pipeline 3 is detected in real time, and the flow of the electric proportional pump 12 is controlled according to the detection result, so that the system requirement value is met, a small amount of surplus exists, and the flow is matched with the system requirement by the minimum heating value. In addition, by the control mode, all mechanisms in the hydraulic system are in a pressure standby state at any time, so that the response speed of the hydraulic system can be effectively improved.
The invention also provides a control method of the hydraulic system, which is used for controlling the hydraulic system.
As shown in fig. 2, the control method of the hydraulic system includes the steps of:
step S201: predicting total flow requirements required by all working units according to the current of each working unit, and controlling the opening of the electric proportional pump according to the total flow requirements;
step S202: detecting unit flow overflowed by a three-way flow valve of a bypass overflow pipeline or a pressure value on a bypass overflow pipeline positioned behind the three-way flow valve;
step S203: and adjusting the opening degree of the electric proportional pump according to the unit flow or the pressure value.
When the hydraulic system works, the controller predicts total flow requirements required by all working units according to the current of each working unit, and controls the electric proportional pump 12 according to the total flow requirements to supply the preliminary current value of the electric proportional pump 12, so that the flow provided by the electric proportional pump 12 can be quickly matched to the vicinity of the required value of the hydraulic system. Then the oil flowing through the bypass overflow pipe 3 is detected, and the electric proportional pump 12 is finely adjusted according to the detected unit flow or pressure value.
In the control process, the controller judges whether the unit flow or the pressure value is in a preset range; if the unit flow or the pressure value is judged to reach the upper threshold value, controlling to reduce the opening of the electric proportional pump 12; if it is determined that the unit flow rate or the pressure value reaches the lower threshold value, the opening degree of the electric proportional pump 12 is controlled to be increased.
For example, if the detection device detects that the back pressure value is 0 or less than the lower limit of the preset range, it is considered that no excessive flow of the electric proportional pump 12 overflows from the three-way flow valve 31, and at this time, the controller increases the current of the electric proportional pump 12 and increases the output of the oil until the three-way flow valve 31 has a certain excessive flow (the back pressure value generated by detecting the overflow flow of the three-way flow valve is determined). If the back pressure value generated by the surplus flow of the three-way flow valve 31 is detected to be too high and exceeds the upper limit of the preset range, the flow supplied by the electric proportional pump 12 is considered to be too high and exceeds the system requirement, and at the moment, the controller adjusts the current of the electric proportional pump 12 to be small and reduces the flow output of the electric proportional pump 12. Thus, the flow rate of the electric proportional pump 12 is controlled to meet the requirement value of the system and a small amount of margin is provided, so that the electric proportional pump 12 can be matched with the requirement of the system with the least heating value. In addition, in the control mode, the electric proportional pump 12 is in a pressure standby state at any time, so that the response speed of the hydraulic system can be effectively improved.
According to the control method of the hydraulic system provided by the embodiment of the invention, a feedback mechanism is introduced by utilizing the three-way flow valve 31, the oil liquid state flowing through the bypass overflow pipeline 3 is detected in real time, and the flow of the electric proportional pump 12 is controlled according to the detection result, so that the system requirement value is met, a small amount of surplus exists, and the flow is matched with the system requirement by using the minimum heating value. In addition, by the control mode, all mechanisms in the hydraulic system are in a pressure standby state at any time, so that the response speed of the hydraulic system can be effectively improved.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. A hydraulic system, comprising:
a hydraulic oil tank;
the oil inlet of the electric proportional pump is communicated with the hydraulic oil tank;
the oil inlets of the main oil supply pipeline and the bypass overflow pipeline are respectively connected with the oil outlets of the electric proportional pumps, and the oil outlets of the bypass overflow pipeline are connected with the hydraulic oil tank;
the multi-way valve assembly comprises a multi-way working link and a three-way flow valve, the multi-way working link is respectively communicated with the main oil supply pipeline, and the three-way flow valve is connected in series on a bypass overflow pipeline;
detecting means for detecting a unit flow rate overflowed from the three-way flow valve or a pressure on the bypass overflow pipe located after the three-way flow valve;
and the controller is respectively and electrically connected with the electric proportional pump, the multi-path working unit and the detection device, and controls the electric proportional pump according to the detection result of the detection device.
2. The hydraulic system of claim 1, wherein a damping orifice is provided in the bypass return line after the three-way flow valve, and the detecting device is a pressure detecting device for detecting a pressure in the line between the damping orifice and the three-way flow valve.
3. The hydraulic system of claim 1, wherein the detection device is a flow detection device for detecting a unit flow of the three-way flow valve.
4. The hydraulic system of claim 1, wherein a damping orifice is provided in the bypass overflow line after the three-way flow valve, and two ends of the damping orifice are connected in parallel with a bypass overflow valve.
5. The hydraulic system of claim 1, wherein a bypass solenoid valve is disposed in the bypass relief line, and a spring chamber of the three-way flow valve communicates with the return spring chamber of the multiplex work train via the bypass solenoid valve to communicate with the hydraulic tank.
6. The hydraulic system of claim 1, further comprising: the main overflow valve, the pilot filter and the pilot pressure reducing valve;
an oil inlet of the main overflow valve is communicated with an oil outlet of the electric proportional pump, and an oil outlet of the main overflow valve is communicated with the hydraulic oil tank; the oil inlet of the pilot relief valve is connected to a pipeline between the oil inlet of the main overflow valve and the oil outlet of the electric proportional pump through the pilot filter, the oil outlet of the pilot relief valve is communicated with the oil inlet spring cavity of the multi-path working unit, and the oil return port of the pilot relief valve is communicated with the hydraulic oil tank.
7. The hydraulic system of claim 1, further comprising: an oil absorption filter and a high pressure filter; an oil inlet of the electric proportional pump is connected with the hydraulic oil tank through the oil suction filter; and an oil outlet of the electric proportional pump is connected with the high-pressure filter.
8. A construction machine, comprising: the hydraulic system of any one of claims 1-7.
9. A control method of a hydraulic system according to any one of claims 1 to 7, characterized by comprising the steps of:
predicting total flow requirements required by all working units according to the current of each working unit, and controlling the opening of the electric proportional pump according to the total flow requirements;
detecting unit flow overflowed by a three-way flow valve of the bypass overflow pipeline or a pressure value on the bypass overflow pipeline after the three-way flow valve;
and adjusting the opening degree of the electric proportional pump according to the unit flow rate or the pressure value.
10. The method of controlling a hydraulic system according to claim 9, wherein the specific step of adjusting the opening degree of the electric proportional pump according to the unit flow rate or the pressure value includes:
judging whether the unit flow or the pressure value is in a preset range or not;
if judging that the unit flow or the pressure value reaches the upper threshold value, controlling to reduce the opening of the electric proportional pump; and if the unit flow rate or the pressure value reaches the lower threshold value, controlling to increase the opening of the electric proportional pump.
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