CN114810696A - Hydraulic system, control method and wheel excavator - Google Patents
Hydraulic system, control method and wheel excavator Download PDFInfo
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- CN114810696A CN114810696A CN202210455928.3A CN202210455928A CN114810696A CN 114810696 A CN114810696 A CN 114810696A CN 202210455928 A CN202210455928 A CN 202210455928A CN 114810696 A CN114810696 A CN 114810696A
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- 238000000034 method Methods 0.000 title claims abstract description 16
- 239000003921 oil Substances 0.000 claims description 135
- 239000010720 hydraulic oil Substances 0.000 claims description 11
- 238000010586 diagram Methods 0.000 description 2
- 238000009412 basement excavation Methods 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
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Classifications
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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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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
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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
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B2013/002—Modular valves, i.e. consisting of an assembly of interchangeable components
- F15B2013/004—Cartridge valves
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- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Mechanical Engineering (AREA)
- Mining & Mineral Resources (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Fluid-Pressure Circuits (AREA)
- Operation Control Of Excavators (AREA)
Abstract
The invention relates to a hydraulic system, aiming at solving the problem that the existing hydraulic system is difficult to be compatible with large flow control and small flow fine control; the hydraulic system, the control method and the wheel type excavator are provided, wherein an oil inlet and a first working oil port of an electro proportional valve in the hydraulic system are correspondingly connected with a pressure oil source and a first oil port of a hydraulic actuating element; an oil inlet and an oil outlet of the switching electromagnet are correspondingly communicated with an oil inlet and a first working oil port of the electro-proportional valve, and the controller outputs electro-proportional valve control current for controlling the opening degree of a valve port from the oil inlet of the electro-proportional valve to the first working oil port according to an operating signal of the operating device; when the operation signal is smaller than or equal to the minimum signal value of the full opening of the valve port, the controller controls the opening and closing electromagnetic valve to be in a cut-off state, otherwise, the opening and closing electromagnetic valve is controlled to be in a conducting state. The invention can be well compatible with the fine operation control of small flow and the high-speed action operation control of large flow.
Description
Technical Field
The present invention relates to a hydraulic system, and more particularly, to a hydraulic system, a control method, and a wheel excavator.
Background
In the field of engineering machinery, hydraulic actuators such as oil cylinders and motors are used for driving related parts, so that the actions of the related parts of the engineering machinery are realized. The hydraulic system for driving and controlling the hydraulic actuator comprises the hydraulic actuator, a control valve for controlling the hydraulic actuator and a pressure oil source for providing pressure oil for the action of the hydraulic actuator. The control valve is connected between the hydraulic actuator and the source of pressurized oil. The control valve adopts electric control or hydraulic control, and a valve core of the control valve usually moves axially to open or close a valve port so as to realize the control of a hydraulic actuator.
Under the condition that pressure oil provided by a pressure oil source is sufficient, the speed of the action of the hydraulic actuator is related to the opening degree of a valve port, the opening degree of the valve port is large, the flow passing through the control valve is large, the action of the hydraulic actuator is rapid, and otherwise, the action of the hydraulic actuator is slow. For the control of a hydraulic actuator requiring a large flow rate, a control valve with a large-diameter valve core is often adopted, and when the control valve with the large-diameter valve core is used for controlling the flow rate, the opening degree of a valve port is changed quickly, so that fine operation is not suitable for being performed. On the engineering machinery, some hydraulic actuators have different requirements under different working conditions, for example, a walking motor of a wheel excavator needs to rotate at a high speed when the hydraulic actuators run on a road, so as to obtain a higher running speed; however, when performing excavation work, the travel motor needs to be operated at a low speed in order to perform fine operation control. Therefore, the contradiction between large flow fast action control and small flow fine operation control often appears on the hydraulic system of the engineering machinery.
Disclosure of Invention
The invention aims to solve the technical problem that large-flow control and small-flow fine control are difficult to be compatible in the conventional hydraulic system, and provides a hydraulic system, a control method and a wheel type excavator, which meet the requirements of large-flow quick action control and small-flow fine control in the hydraulic system.
The technical scheme for realizing the purpose of the invention is as follows: there is provided a hydraulic system for a hydraulic machine,
the hydraulic proportional control system comprises a hydraulic actuator, a pressure oil source, an electric proportional valve, a controller for controlling the electric proportional valve, and an operating device which is connected with the controller and is used for operating the hydraulic actuator; an oil inlet and a first working oil port of the electro-proportional valve are correspondingly connected with a pressure oil source and a first oil port of the hydraulic actuating piece;
the controller outputs an electric proportional valve control current for controlling the opening degree of a valve port between an oil inlet of the electric proportional valve and the first working oil port according to an operation signal of the operation device; the hydraulic control system is characterized by further comprising an opening and closing electromagnetic valve, wherein an oil inlet and an oil outlet of the opening and closing electromagnetic valve are correspondingly communicated with an oil inlet and a first working oil port of the electro-proportional valve, and a control end of the opening and closing electromagnetic valve for controlling the opening and closing of the opening and closing electromagnetic valve is connected with a controller; when the operation signal is smaller than or equal to the minimum signal value of the full opening of the valve port, the controller controls the opening and closing electromagnetic valve to be in a cut-off state, and when the operation signal is larger than the minimum signal value of the full opening of the valve port, the controller controls the opening and closing electromagnetic valve to be in a conducting state.
In the invention, when the operation amplitude of the operating device is smaller, the opening and closing electromagnetic valve is in a closed state, and oil flowing to the hydraulic actuating element is controlled by the electro-proportional valve, so that the fine operation control is more suitable; when the operation amplitude of the operating device is large, and the value of an operation signal (current or voltage) output by the operating device is larger than the minimum signal value of the full-open valve port, the opening-closing electromagnetic valve is in a conducting state, oil can flow to the hydraulic actuating element through the opening-closing electromagnetic valve and the electro-proportional valve, the maximum flow rate flowing to the hydraulic actuating element is greatly increased, and the hydraulic actuating element is suitable for large-flow quick action. Therefore, the invention can be well compatible with the fine operation control of small flow and the high-speed action operation control of large flow.
When the control device is controlled, the control amplitude is effectively increased, the control signal is gradually increased from zero, the control current of the electro-proportional valve output by the controller according to the control signal of the control device is gradually increased, and the valve port between the oil inlet of the electro-proportional valve and the first working oil port is also gradually increased; when the control signal is increased to a certain value, the opening degree of a valve port between the oil inlet of the electro-proportional valve and the first working oil port is increased to the maximum, namely, the valve port is fully opened, and the value of the control signal is the minimum signal value of the fully opened valve port at the moment.
In the hydraulic system, when the operating signal is greater than the minimum signal value of the full opening of the valve port, the controller always outputs the control current of the electro-proportional valve, which enables the valve port of the electro-proportional valve to be fully opened. At the moment, the opening degrees of the valve ports of the electro-proportional valve and the opening and closing electromagnetic valve reach the maximum value, the pressure oil flowing to the hydraulic actuating element changes along with the change of the flow rate of the pressure oil provided by the pressure oil source, and the speed of the hydraulic actuating element can be controlled by controlling the flow rate of the pressure oil source. Further, the pressure oil source comprises a hydraulic pump and a power driving device for driving the hydraulic pump to suck oil from a hydraulic oil tank, a pump port of the hydraulic pump is connected with an oil inlet of the electro-proportional valve, the controller is connected with a control unit of the power driving device, and when the manipulation signal is larger than the minimum valve opening signal value, the controller sends a rotating speed signal to the control unit of the power driving device according to the manipulation signal so that the rotating speed of the power driving device is changed positively and correlatively with the manipulation signal. And controlling the rotating speed of the power driving device, namely controlling the rotating speed of the hydraulic pump according to the control signal, thereby realizing the control of the flow rate of the hydraulic pump.
In the hydraulic system, when the manipulation signal is greater than the minimum signal value of full opening of the valve port, the electric proportional valve control current output by the controller is changed along with the positive correlation of the magnitude of the manipulation signal in the range between Iint and Imax, wherein Imax is the electric proportional valve control current for making the valve port of the electric proportional valve fully open, and Iint is the electric proportional valve control current for making the valve port of the electric proportional valve open to a preset opening degree; the sum of the valve port flow area of the preset opening degree of the electric proportional valve and the valve port flow area when the opening-closing electromagnetic valve is conducted is equal to the valve port flow area when the valve port of the electric proportional valve is fully opened. When the manipulation signal is increased to reach the minimum signal value of the full opening of the valve port, the electro-proportional valve is fully opened, and the control current of the electro-proportional valve is Imax and is the maximum value; if the operation signal is increased slightly, the controller controls the opening of the opening-closing electromagnetic valve, meanwhile, the control current of the electro-proportional valve is reduced to Iint, when the control current of the electro-proportional valve is Iint, the opening degree of a valve port of the electro-proportional valve can only reach a certain preset value, at the moment, the sum of the flow area of the valve port of the electro-proportional valve and the flow area of the valve port of the opening-closing electromagnetic valve is equal to the flow area when the valve port of the electro-proportional valve is fully opened, namely in the hydraulic system, when the operation signal is changed from the minimum signal value equal to the full opening of the valve port to a value slightly larger than the minimum signal value of the full opening of the valve port, the total flow areas of the electro-proportional valve and the opening-closing electromagnetic valve are equal or close, and sudden hydraulic impact is avoided, so that the sudden change of the flow areas is avoided. Similarly, when the operation signal is changed from the minimum signal value larger than the full-opening valve port to the minimum signal value equal to the full-opening valve port, the control current of the electro-proportional valve is also changed from Iint to Imax, namely the electro-proportional valve is increased from the preset value opening degree to full-opening, and meanwhile, the opening and closing electromagnetic valve is also changed from opening to closing, so that violent hydraulic impact caused by sudden change of the flow area is avoided.
In the hydraulic system, when the manipulation signal is smaller than or equal to the minimum signal value of full opening of the valve port, the controller outputs the electro-proportional valve control current which is positively and correlatively changed with the magnitude of the manipulation signal in the range between the zero value and the Imax.
The technical scheme for realizing the purpose of the invention is as follows: the control method of the hydraulic system is characterized in that the hydraulic system comprises an electro-proportional valve, an opening and closing electromagnetic valve, a controller and an operating device, wherein an oil inlet and a first working oil port of the electro-proportional valve are correspondingly connected with a pressure oil source and a first oil port of a hydraulic actuator; the control method comprises the following steps:
the controller outputs an electric proportional valve control current for controlling the opening degree of a valve port of the electric proportional valve according to an operation signal of the operation device;
when the operation signal is smaller than or equal to the minimum signal value of the full opening of the valve port, the controller controls the opening and closing electromagnetic valve to be in a cut-off state, otherwise, the opening and closing electromagnetic valve is controlled to be in a conduction state, namely when the operation signal is larger than the minimum signal value of the full opening of the valve port, the controller controls the opening and closing electromagnetic valve to be in the conduction state.
In the control method of the hydraulic system, the pressure oil source comprises a hydraulic pump and a power driving device for driving the hydraulic pump to suck oil from a hydraulic oil tank, a pump port of the hydraulic pump is connected with an oil inlet of an electro-proportional valve, and the controller is connected with a control unit of the power driving device;
when the operation signal is larger than the minimum valve opening signal value, the controller always outputs the electric proportional valve control current which enables the valve opening of the electric proportional valve to be fully opened, and sends a rotating speed signal to the control unit of the power driving device according to the size of the operation signal so that the rotating speed of the power driving device is changed along with the positive correlation of the size of the operation signal.
In the control method of the hydraulic system, when the manipulation signal is larger than the minimum value of the full-open valve port signal, the controller outputs the electro-proportional valve control current which is in positive correlation with the manipulation signal in the range between Iint and Imax.
In the control method of the hydraulic system, when the manipulation signal is less than or equal to the minimum signal value of full opening of the valve port, the controller outputs the electric proportional valve control current which is in a range between a zero value and a control current value of the electric proportional valve for enabling the valve port of the electric proportional valve to be fully opened and is in positive correlation change with the magnitude of the manipulation signal.
The technical scheme for realizing the purpose of the invention is as follows: the wheel excavator is characterized by comprising the hydraulic system, wherein a first oil port of the hydraulic actuating piece is an advancing oil inlet of the walking motor.
Compared with the prior art, the invention can be well compatible with small-flow fine operation control and large-flow high-speed action operation control.
Drawings
FIG. 1 is a hydraulic schematic of the hydraulic system of the present invention.
Fig. 2 is a block diagram of the control circuit of the hydraulic system of the present invention.
Fig. 3 is a partial hydraulic schematic diagram of a hydraulic system of a wheel excavator according to the present invention.
Part names and serial numbers in the figure:
the hydraulic control system comprises a hydraulic oil tank 10, a double-pump oil supply assembly 20, a hydraulic pump 21, a second hydraulic pump 22, a power driving device 23, a main control valve assembly 30, a pilot-controlled main valve 31, a slewing main valve 32, an arm main valve 33, a dozer main valve 34, a bucket main valve 35, a boom main valve 36, a hydraulic actuator 40, an electric proportional pilot valve 50, an electric proportional pressure reducing valve 51, a first electromagnetic valve 52, a second electromagnetic valve 53, an opening and closing electromagnetic valve 60, a cartridge valve 61, a two-position three-way electromagnetic valve 62, a controller 7 and an operating device 8.
Detailed Description
The following description of the embodiments refers to the accompanying drawings.
The first embodiment.
As shown in fig. 1 and 2, the hydraulic system in the present embodiment includes a hydraulic actuator 40, a pressure oil source, an electro-proportional valve, a controller 7 for controlling the electro-proportional valve, an operating device 8 connected to the controller 7 for operating the hydraulic actuator, an on-off solenoid valve 60, and the like.
The pressure oil source is composed of a hydraulic oil tank 10, a hydraulic pump 21 having an oil suction port connected to the hydraulic oil tank, and a power driving device 23 for driving the hydraulic pump 21 to rotate, the power driving device 23 is an electric motor or a fuel engine, and the flow rate of the hydraulic pump 21 can be adjusted within a certain range by controlling the rotation speed of the hydraulic pump 21 by controlling the rotation speed of the power driving device 23.
The electro proportional valve 3 is composed of a pilot main valve 31 and an electro proportional pilot valve 50, and the electro proportional pilot valve 50 is composed of an electro proportional pressure reducing valve 51, a first electromagnetic valve 52, and a second electromagnetic valve 53. The oil inlet end of the electric proportional pressure reducing valve 51 is connected with a pilot oil source, and the oil outlet end is simultaneously connected with the oil inlet ends of the first electromagnetic valve 52 and the second electromagnetic valve 53; the first solenoid valve 52 and the second solenoid valve 53 are both two-position three-way solenoid valves. The oil outlet ends of the first solenoid valve 52 and the second solenoid valve 53 are correspondingly connected with the left hydraulic control end and the right hydraulic control end of the hydraulic control main valve 31, the oil return ends are both connected with the hydraulic oil tank 10, and the first solenoid valve 52 and the second solenoid valve 53 communicate the oil outlet end of the electro-proportional pressure reducing valve 51 with the corresponding hydraulic control end of the hydraulic control main valve 31 or communicate the hydraulic control end of the hydraulic control main valve with the hydraulic oil tank. The electro-proportional pressure reducing valve 51 outputs pilot pressure oil of a corresponding pressure in accordance with an electro-proportional valve control current applied thereto, and the pilot pressure oil acts on the left end of the pilot main valve 31 through the first electromagnetic valve 52 or acts on the right end of the pilot main valve 31 through the second electromagnetic valve 53, so that the pilot main valve 31 opens a corresponding valve port opening degree in the left position or the right position. The pressure of the pilot pressure oil output by the electro-proportional pressure reducing valve 51, the electro-proportional valve control current, and the valve port opening of the pilot main valve are changed in a positive correlation, that is, the larger the electro-proportional valve control current is, the larger the pressure of the output pilot pressure oil is, and the larger the valve port opening of the pilot main valve corresponding to the function level is.
In this embodiment, the electro-proportional pilot valve 50 may be formed by two electro-proportional pressure reducing valves, and one electro-proportional pressure reducing valve is connected between each of the two pilot ends of the pilot main valve 31 and the pilot pressure oil source.
The pilot-controlled main valve 31 is a three-position valve, an oil inlet end of the pilot-controlled main valve is connected with a pump port of the hydraulic pump 21, an oil return port of the pilot-controlled main valve is connected with the hydraulic oil tank 10, and a first working oil port (a1 port) and a second working oil port (B1 port) are correspondingly connected with a first oil port (a port) and a second oil port (B port) of the hydraulic actuating member. When the electric proportional pressure reducing valve 51 and the first electromagnetic valve 52 are powered on and the pilot-controlled main valve 31 is in the left position, the oil inlet of the pilot-controlled main valve 31 is communicated with the first working oil port (port a 1), the pressure oil output by the hydraulic pump 21 enters the first oil port of the hydraulic motor through the pilot-controlled main valve 31, and the hydraulic motor rotates forward; when the electro-proportional pressure reducing valve 51 and the second electromagnetic valve 53 are energized, and the pilot-controlled main valve 31 is in the right position, the oil inlet of the pilot-controlled main valve 31 is communicated with the second working oil port (port B1), the pressure oil output by the hydraulic pump 21 enters the second oil port of the hydraulic motor through the pilot-controlled main valve 31, and the hydraulic motor rotates reversely. The structure type of the pilot-controlled main valve 31 varies according to the function of the hydraulic actuator 40 connected thereto, for example, when the hydraulic actuator is a hydraulic motor with unidirectional rotation, the pilot-controlled main valve 31 can be simplified as a two-position valve, only one working oil port of the two-position valve is connected to the first oil port of the hydraulic motor, and the second oil port of the hydraulic motor can be directly connected to the oil tank, in which case, the electro-proportional pilot valve 50 also varies accordingly.
The on-off solenoid valve 60 is composed of a cartridge valve 61 and a two-position three-way solenoid valve 62, and the cartridge valve 61 is a two-position two-way valve in a closed/off state or an on/off state. The oil inlet of the cartridge valve 61 is communicated with the oil inlet of the pilot-controlled main valve 31, that is, with the pump port of the hydraulic pump 21. The outlet port of the cartridge valve 61 communicates with the first working port (port a 1) of the pilot-controlled main valve 31, that is, the first port of the hydraulic actuator 40. A first oil port of the two-position three-way electromagnetic valve 62 is connected with a control end of the cartridge valve 61, a second oil port of the two-position three-way electromagnetic valve is connected with an oil inlet of the cartridge valve 61, and a third oil port of the two-position three-way electromagnetic valve is connected with the hydraulic oil tank 10. One of the first oil port is communicated with the second oil port or the third oil port. When the two-position three-way electromagnetic valve 62 is electrified, the first oil port and the third oil port are communicated, and the cartridge valve is opened; when the two-position three-way electromagnetic valve 62 is powered off, the first oil port and the second oil port are communicated, and the cartridge valve 61 is closed and stopped.
As shown in fig. 2, the operation device 8, the two-position three-way solenoid valve of the electro proportional pilot valve 50 and the on-off solenoid valve 60 of the electro proportional valve are connected to the controller 7,
the operating device 8 is used for operating and controlling the hydraulic actuators 40. The control device 8 may be an electric control handle, an operator performs control swing, the electric control handle transmits a corresponding control signal to the controller 7 when swinging, the control signal may be a voltage signal or a current signal, the controller 7 controls the electric proportional pilot valve 50, the opening and closing electromagnetic valve 60 and other devices according to the control signal, for example, when the electric control handle swings forward, the controller makes the first electromagnetic valve 52 electrically conducted according to the control signal output by the electric proportional pilot valve swinging forward, and outputs a corresponding electric proportional valve control current to the electric proportional pressure reducing valve 51 according to the magnitude of the control signal, the hydraulic control main valve 31 is in the left position under the action of pilot pressure oil, the valve port is opened to a corresponding opening degree, the pressure oil output by the hydraulic pump 21 enters the first oil port of the hydraulic motor through the hydraulic control main valve 31, so that the hydraulic motor rotates forward. When the electric control handle swings backwards, the controller 7 makes the second electromagnetic valve 53 electrically conducted according to the manipulation signal output by the electric control handle swinging backwards, and outputs a corresponding electric proportional valve control current to the electric proportional pressure reducing valve 51 according to the magnitude of the manipulation signal, the hydraulic control main valve 31 is in the right position under the action of pilot pressure oil, the valve port is opened to a corresponding opening degree, and the pressure oil output by the hydraulic pump 21 enters the second oil port of the hydraulic motor through the hydraulic control main valve 31, so that the hydraulic motor rotates reversely.
The controller 7 is connected to the power driving device 23 and is capable of sending a rotational speed command to the power driving device 23 to operate the power driving device 23 at a corresponding rotational speed.
In the present embodiment, when the pilot controller 8 operates the pilot main valve 31 in the right position, the controller 7 outputs the electro-proportional valve control current for controlling the electro-proportional pressure reducing valve 51 in accordance with the pilot signal, and the magnitude of the electro-proportional valve control current, the valve port opening degree of the pilot main valve, and the pilot signal output by the controller are in a positive correlation change relationship, that is, the larger the pilot signal is, the larger the electro-proportional valve control current and the valve port opening degree of the pilot main valve are, until the electro-proportional valve control current reaches the maximum value and the valve port of the pilot main valve is fully opened, and in this process, the open-close solenoid valve is in the closed state.
When the pilot device 8 performs the pilot operation such that the pilot valve 31 operates in the left position, the hydraulic system is controlled as follows:
the controller 7 energizes the first solenoid valve 52 in the electro-proportional pilot valve according to the operation signal, and communicates the oil outlet end of the electro-proportional pressure reducing valve 51 with the pilot-controlled left end of the pilot-controlled main valve 31.
When the manipulation signal is smaller than or equal to the minimum signal value of the full opening of the valve port, the controller 7 outputs the proportional valve control current which is in the range of zero value and Imax and is in positive correlation change with the magnitude of the manipulation signal. Imax is the electro proportional valve control current value at which the valve port of the pilot main valve is fully opened. When the pilot signal is equal to or less than the minimum valve port full-open signal value, the controller 7 controls the on-off solenoid valve 60 to be in the closed state, and the pressure oil output from the hydraulic pump 21 flows to the hydraulic actuator only through the pilot main valve 31.
The operation signal is gradually increased from zero, the electric proportional valve control current output by the controller 7 according to the size of the operation signal of the operation device 8 is gradually increased, and the opening degree of a valve port of the hydraulic control main valve is also gradually increased; when the operation signal is increased to a certain value, the opening degree of the valve port of the hydraulic control main valve is increased to the maximum, namely, the valve port is fully opened, and the value of the operation signal is the minimum signal value of the fully opened valve port.
When the pilot signal is greater than the minimum valve port full-open signal value, the controller 7 controls the on-off solenoid valve 60 to be in a conducting state, and the pressure oil output from the hydraulic pump 21 can flow to the hydraulic actuator through the pilot main valve 31 and the on-off solenoid valve 60.
When the operation signal is greater than the minimum valve port opening signal value, the electric proportional valve has two control modes, the first control mode is that the controller always outputs the electric proportional valve control current for fully opening the valve port of the pilot-controlled main valve, the valve port openings of the pilot-controlled main valve and the opening and closing electromagnetic valve reach the maximum value, the pressure oil flowing to the hydraulic actuator changes along with the change of the pressure oil flow provided by the hydraulic pump, and the control on the action speed of the hydraulic actuator 40 can be realized by controlling the flow of the hydraulic pump 21. At this time, the controller 7 may transmit a rotation speed signal to the control unit of the power driving apparatus 23 according to the magnitude of the manipulation signal so that the rotation speed of the power driving apparatus 23 is changed in positive correlation with the magnitude of the manipulation signal. The higher the manipulation signal value output from the manipulation device 8, the higher the rotation speed of the power drive device 23, the higher the flow rate of the pressure oil output from the hydraulic pump 21, and the faster the operation of the hydraulic actuator 40, and the faster the rotation speed if the hydraulic actuator is a hydraulic motor.
When the operation signal is larger than the minimum signal value of the full opening of the valve port, the second control mode of the electro-proportional valve is as follows: when the operation signal is increased from the minimum valve port full-open signal value to a value slightly larger than the minimum valve port full-open signal value, the controller 7 controls the on-off electromagnetic valve 60 to be opened and conducted, and controls the electric proportional valve control current of the electric proportional pressure reducing valve 51 to be reduced from Imax to Iint. The electro-proportional pressure reducing valve 51 outputs corresponding pilot pressure oil under the action of the electro-proportional valve control current Iint to open the valve port of the pilot main valve 31 to a predetermined valve port opening degree; the sum of the valve-port flow area of the predetermined valve-port opening degree of the pilot-controlled main valve 31 and the valve-port flow area when the on-off solenoid valve 60 is on is equal to the valve-port flow area when the valve port of the pilot-controlled main valve 31 is fully open. When the operation signal is increased to reach the minimum signal value of full opening of the valve port, the hydraulic control main valve is fully opened, and the electric proportional valve controls the current to be Imax which is the maximum value; if the operation signal continues to increase slightly, the controller controls the on-off solenoid valve 60 to open, and at the same time, the electric proportional valve control current is reduced to Iint, when the electric proportional valve control current is Iint, the opening degree of the valve port of the hydraulic control main valve can only reach a certain predetermined value, at this time, the sum of the valve port flow area of the hydraulic control main valve and the valve port flow area of the on-off solenoid valve 60 is equal to the flow area when the valve port of the hydraulic control main valve 31 is fully opened, that is, in the hydraulic system, when the operation signal changes from the value equal to the minimum signal value of the full opening of the valve port to a value slightly larger than the minimum signal value of the full opening of the valve port, the total flow areas of the hydraulic control main valve 31 and the on-off solenoid valve 60 are equal or close, and sudden hydraulic impact caused by sudden change of the flow areas is avoided. Similarly, when the operation signal changes from a value slightly larger than the minimum signal value of the full-open valve port to a value equal to the minimum signal value of the full-open valve port, the control current of the electro-proportional valve also changes from Iint to Imax, that is, the opening degree of the hydraulic control main valve is increased from a predetermined value to the full-open state, and the opening and closing electromagnetic valve 60 also changes from the opening state to the closing state, so that the generation of violent hydraulic impact due to sudden change of the flow area is avoided.
In the second control mode, when the pilot signal is greater than the minimum valve port full-open signal value, the controller 7 outputs an electro-proportional valve control current that varies positively with the magnitude of the pilot signal within a range between Iint and Imax, that is, the valve port opening of the pilot-controlled main valve varies positively with the magnitude of the pilot signal within a range between a predetermined valve port opening and full-open, and the larger the pilot signal is, the larger the valve port opening of the pilot-controlled main valve is.
In the present embodiment, when the operation signal is less than or equal to the minimum signal value of the fully open valve port, the pressure oil output by the hydraulic pump 21 can only flow to the hydraulic actuator through the pilot main valve 31, and at this stage, the fine operation control can be performed on the hydraulic actuator 40; when the operation signal is greater than the minimum signal value of the full opening of the valve port, the pressure oil output by the hydraulic pump can flow to the hydraulic executing part through the hydraulic control main valve and the opening and closing electromagnetic valve, the maximum value of the flow is increased, and the hydraulic executing part works in a high-flow high-speed action state, so that the hydraulic system disclosed by the invention is well compatible with small-flow fine operation control and large-flow high-speed action operation control, and meets corresponding requirements.
Example two.
Fig. 3 shows a part of oil passages in a hydraulic system of a wheel excavator. The hydraulic system of the traveling part of the wheel excavator is the hydraulic system of the first embodiment, that is, the hydraulic actuator 40 of the first embodiment is the traveling motor of the excavator, the hydraulic pump 21 and the second hydraulic pump 22 constitute the dual-pump oil supply assembly 20, the pilot main valve 31 is the traveling main valve, and the main control valve assembly 30 is constituted by the pilot main valve 31, the swing main valve 32, the arm main valve 33, the boom main valve 36, the bucket main valve 35, and the dozer main valve 34, wherein the pilot main valve 31, the swing main valve 32, and the arm main valve 33 are supplied with oil by the hydraulic pump 21; the boom linkage main valve 36, the bucket linkage main valve 35, and the dozer linkage main valve 34 are supplied with oil from the second hydraulic pump.
In the hydraulic system, a first oil port of the hydraulic motor is an advancing oil inlet, namely when pressure oil is fed into the first oil port of the hydraulic motor, the hydraulic motor rotates forwards, and the wheel excavator runs forwards; when the second oil port of the hydraulic motor is opened, the hydraulic motor rotates reversely, and the wheel type excavator runs backwards.
In the wheel excavator, when the wheel excavator is controlled to walk, if the operation range of the operating device 8 is small (when the signal value in the groove output by the operating device is smaller than the minimum signal value of the full-open valve port), the flow of the pressure oil flowing to the walking motor is small, and the wheel excavator is suitable for fine operation control, but if the operation range of the operating device is large (when the signal value in the groove output by the operating device is larger than the minimum signal value of the full-open valve port), the flow of the pressure oil flowing to the walking motor is large, so that the wheel excavator is suitable for being driven at a high speed, such as on a road, and meets the requirement of the speed on the road.
On a wheel excavator, the operating device can adopt various forms, such as running by using an electric control handle, controlling the working position of the pilot-controlled main valve according to the swinging direction of the electric control handle, controlling the opening degree of the pilot-controlled main valve and opening and closing of the opening and closing electromagnetic valve according to the swinging amplitude of the electric control handle. The operating device can also be composed of a foot-operated accelerator pedal and a gear handle, the working position of the hydraulic control main valve is controlled according to the gear of the gear handle, the opening degree of the hydraulic control main valve and the opening and closing of the opening and closing electromagnetic valve are controlled according to the amplitude of the foot-operated accelerator pedal, and the rotating speed of the walking motor is controlled.
Claims (10)
1. A hydraulic system comprises a hydraulic actuator, a pressure oil source, an electric proportional valve, a controller for controlling the electric proportional valve, and an operating device connected with the controller and used for operating the hydraulic actuator; an oil inlet and a first working oil port of the electro-proportional valve are correspondingly connected with a pressure oil source and a first oil port of the hydraulic actuating piece;
the controller outputs an electric proportional valve control current for controlling the opening degree of a valve port between an oil inlet of the electric proportional valve and the first working oil port according to an operation signal of the operation device; the hydraulic control system is characterized by further comprising an opening and closing electromagnetic valve, wherein an oil inlet and an oil outlet of the opening and closing electromagnetic valve are correspondingly communicated with an oil inlet and a first working oil port of the electro-proportional valve, and a control end of the opening and closing electromagnetic valve for controlling the opening and closing of the opening and closing electromagnetic valve is connected with a controller; when the operation signal is smaller than or equal to the minimum signal value of the full opening of the valve port, the controller controls the opening and closing electromagnetic valve to be in a cut-off state, and when the operation signal is larger than the minimum signal value of the full opening of the valve port, the controller controls the opening and closing electromagnetic valve to be in a conducting state.
2. The hydraulic system of claim 1, wherein the controller always outputs the electro-proportional valve control current to fully open the electro-proportional valve port when the pilot signal is greater than the valve port fully-open minimum signal value.
3. The hydraulic system of claim 2, wherein the pressure oil source comprises a hydraulic pump and a power driving device for driving the hydraulic pump to suck oil from a hydraulic oil tank, a pump port of the hydraulic pump is connected with an oil inlet of the electric proportional valve, the controller is connected with a control unit of the power driving device, and when the manipulation signal is greater than the minimum signal value of full-open valve port, the controller sends a rotation speed signal to the control unit of the power driving device according to the magnitude of the manipulation signal, so that the rotation speed of the power driving device is changed positively and dependently with the magnitude of the manipulation signal.
4. The hydraulic system according to claim 1, wherein the controller outputs an electro-proportional valve control current that varies with a positive correlation with the magnitude of the manipulation signal in a range between Iint, which is an electro-proportional valve control current that fully opens an electro-proportional valve port, and Imax, which is an electro-proportional valve control current that opens the electro-proportional valve port to a predetermined opening degree, when the manipulation signal is greater than the valve port full-open minimum signal value; the sum of the valve port flow area of the preset opening degree of the electric proportional valve and the valve port flow area when the opening-closing electromagnetic valve is conducted is equal to the valve port flow area when the valve port of the electric proportional valve is fully opened.
5. The hydraulic system of any one of claims 1 to 4, wherein the controller outputs an electro-proportional valve control current that varies positively with the magnitude of the pilot signal in a range between a zero value and Imax when the pilot signal is equal to or less than a valve port full open minimum signal value.
6. The control method of the hydraulic system is characterized in that the hydraulic system comprises an electric proportional valve, an opening and closing electromagnetic valve, a controller and an operating device, wherein an oil inlet and a first working oil port of the electric proportional valve are correspondingly connected with a pressure oil source and a first oil port of a hydraulic actuating element; the control method comprises the following steps:
the controller outputs an electric proportional valve control current for controlling the opening degree of a valve port of the electric proportional valve according to an operation signal of the operation device;
when the operation signal is smaller than or equal to the minimum signal value of the full opening of the valve port, the controller controls the opening and closing electromagnetic valve to be in a cut-off state, otherwise, the opening and closing electromagnetic valve is controlled to be in a conducting state.
7. The hydraulic system control method according to claim 6, characterized in that:
the pressure oil source comprises a hydraulic pump and a power driving device for driving the hydraulic pump to suck oil from a hydraulic oil tank, a pump port of the hydraulic pump is connected with an oil inlet of the electric proportional valve, and the controller is connected with a control unit of the power driving device;
when the operation signal is larger than the minimum valve opening signal value, the controller always outputs the electric proportional valve control current which enables the valve opening of the electric proportional valve to be fully opened, and sends a rotating speed signal to the control unit of the power driving device according to the size of the operation signal so that the rotating speed of the power driving device is changed along with the positive correlation of the size of the operation signal.
8. The control method of the hydraulic system according to claim 6, wherein the controller outputs the electro-proportional valve control current to follow a magnitude of the manipulation signal in a range between Iint, which is an electro-proportional valve control current that fully opens an electro-proportional valve port, and Imax, which is an electro-proportional valve control current that opens the electro-proportional valve port to a predetermined opening, when the manipulation signal is greater than a valve port full-opening minimum signal value; the sum of the valve port flow area of the preset opening of the electric proportional valve and the valve port flow area when the opening-closing electromagnetic valve is conducted is equal to the valve port flow area when the valve port of the electric proportional valve is fully opened.
9. The hydraulic system control method according to any one of claims 6 to 8, characterized in that the controller outputs an electro proportional valve control current that varies positively in correlation with the magnitude of the pilot signal in a range between zero and Imax when the pilot signal is equal to or less than a valve port full open minimum signal value.
10. A wheeled excavator characterized by having the hydraulic system as recited in any one of claims 1 to 5, wherein the first oil port of the hydraulic actuator is a forward oil inlet port of the traveling motor.
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| CN202210455928.3A CN114810696A (en) | 2022-04-28 | 2022-04-28 | Hydraulic system, control method and wheel excavator |
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| JP2002174202A (en) * | 2000-09-29 | 2002-06-21 | Kobelco Contstruction Machinery Ltd | Hydraulic circuit and construction equipment provided with the hydraulic circuit |
| CN103047204A (en) * | 2013-01-05 | 2013-04-17 | 中联重科股份有限公司 | Engineering machinery and hydraulic control operation system and method thereof |
| CN204715450U (en) * | 2015-02-11 | 2015-10-21 | 徐州徐工基础工程机械有限公司 | Subterranean continuous wall hydraulic grab positive flow system |
| CN108884842A (en) * | 2016-03-31 | 2018-11-23 | 株式会社多田野 | Hydraulic system and emergency operating method |
| CN109563853A (en) * | 2016-11-16 | 2019-04-02 | 日立建机株式会社 | Work machine |
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2022
- 2022-04-28 CN CN202210455928.3A patent/CN114810696A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2002174202A (en) * | 2000-09-29 | 2002-06-21 | Kobelco Contstruction Machinery Ltd | Hydraulic circuit and construction equipment provided with the hydraulic circuit |
| CN103047204A (en) * | 2013-01-05 | 2013-04-17 | 中联重科股份有限公司 | Engineering machinery and hydraulic control operation system and method thereof |
| CN204715450U (en) * | 2015-02-11 | 2015-10-21 | 徐州徐工基础工程机械有限公司 | Subterranean continuous wall hydraulic grab positive flow system |
| CN108884842A (en) * | 2016-03-31 | 2018-11-23 | 株式会社多田野 | Hydraulic system and emergency operating method |
| CN109563853A (en) * | 2016-11-16 | 2019-04-02 | 日立建机株式会社 | Work machine |
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