CN113323933A - Pressure difference matching type bidirectional large-flow hydraulic control device - Google Patents
Pressure difference matching type bidirectional large-flow hydraulic control device Download PDFInfo
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- CN113323933A CN113323933A CN202110557111.2A CN202110557111A CN113323933A CN 113323933 A CN113323933 A CN 113323933A CN 202110557111 A CN202110557111 A CN 202110557111A CN 113323933 A CN113323933 A CN 113323933A
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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
- F15B13/021—Valves for interconnecting the fluid chambers of an actuator
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
- F04B49/06—Control using electricity
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
- F04B49/22—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00 by means of 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
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/027—Check valves
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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Abstract
The invention discloses a pressure difference matching type bidirectional large-flow hydraulic control device. The system mainly comprises a servo motor, a miniature bidirectional gear pump, a controller, a two-position two-way electromagnetic valve and a differential pressure matching type bidirectional flow control valve; the oil inlet and outlet of the miniature bidirectional gear pump are connected with different oil cavities of the control unit, the oil inlet and outlet of the miniature gear pump are controlled by a two-position two-way electromagnetic valve, and the bidirectional gear pump generates controllable micro flow and generates controllable pressure difference by flowing through a throttling channel. The invention can ensure low cost, reliability, convenient and stable control, environmental protection, insensitivity to oil temperature and cleanliness and effective guarantee of the position and speed requirements of large flow when used for accurately controlling large flow.
Description
Technical Field
The invention belongs to a hydraulic control system in the technical field of hydraulic control, and particularly relates to a bidirectional large-flow control system based on a differential pressure matching type flow control valve.
Background
The hydraulic transmission system is widely used for various electromechanical equipment, and the hydraulic valve is a core element for controlling the pressure, flow and direction of liquid in the hydraulic system, and has important influence on the performance, reliability and economy of the hydraulic system. The flow valve adjusts the flow rate by changing the opening degree of a throttle valve port, so as to control the movement speed of load equipment, and is one of three types of hydraulic valves. In the control of many high power systems, flow control valves are required to be able to control large flows accurately and quickly. The traditional large-flow control valve is generally designed into a multi-stage valve form, namely a pilot valve is used for controlling the pressure difference at two ends of a main valve and controlling the movement of a main valve core, so that the large flow is controlled through the main valve core. Therefore, in the multi-stage control valve, displacement control of the pilot valve core to the main valve core is realized in various inter-stage feedback modes, and then flow regulation is finished through the main valve port on the main valve core, so that a larger flow control grade is realized. The problems brought by the control mode are that the requirement on the overall manufacturing precision of the valve is high, the control mode is complex, and the requirement on the cleanliness of system oil of the valve is also high, so that the overall cost of the valve is high, and the use occasion of the valve is limited.
With the increasing demands of flow valves on the aspects of reliability, leakage, opening and closing dynamic characteristics, load adaptability and the like, especially under the condition of large flow, the advantages of various existing large-flow control valves and feedback modes thereof are integrated, the defects that the existing large-flow proportional valve and servo valve are high in cost and difficult to control, and limitations on the aspects of reliability, valve core displacement control precision or response speed and the like are overcome, a novel large-flow control valve or control device is explored and developed based on an innovative flow control mode, and the method is imperative to a large-flow hydraulic control system.
Disclosure of Invention
In order to solve the problems in the background art, the invention provides a pressure difference matching type bidirectional large-flow hydraulic control device, which can ensure low cost, reliability, convenient and stable control, environmental friendliness and insensitivity to the temperature and cleanliness of oil liquid when used for accurately controlling large flow, and can effectively ensure the position and speed requirements of large flow.
The invention creatively realizes the bidirectional large-flow control by using a small-flow device by utilizing the pressure difference matching relation between different throttling ports on the same valve core. The device integrates the function of a hydraulic lock, utilizes a miniature servo motor to drive a miniature gear pump to carry out digital control on part of oil paths of the large-flow control device, generates controllable pressure difference by accurately controlling the flow of hydraulic oil passing through a given throttling channel, and accurately controls the flow in a main oil path in a pressure matching mode. Therefore, the accurate control of bidirectional large flow with small input power is realized.
The technical scheme adopted by the invention is as follows:
pressure difference matching type bidirectional large-flow hydraulic control unit
The system mainly comprises a servo motor, a miniature bidirectional gear pump, a controller, a two-position two-way electromagnetic valve and a differential pressure matching type bidirectional flow control valve;
the pressure difference matching type bidirectional flow control valve comprises a valve body, an upper cavity and a lower cavity which are respectively arranged at the upper part and the lower part in the valve body, the upper cavity and the lower cavity are directly and coaxially communicated, and the inner diameter of the upper cavity at the upper part is larger than that of the lower cavity at the lower part, so that a step is formed between the upper cavity and the lower cavity; a top oil port is formed in the top end of the valve body at the top of the upper cavity, a bottom oil port is formed in the bottom end of the valve body at the bottom of the lower cavity, and a middle oil port and a hydraulic oil port are formed in the side wall of the valve body between the upper cavity and the lower cavity;
the control shaft of the miniature bidirectional gear pump is connected with the servo motor, the servo motor is electrically connected with the controller, one oil port of the miniature bidirectional gear pump is connected with the top oil port of the differential pressure matching type bidirectional flow control valve, and the other oil port of the miniature bidirectional gear pump is connected with the middle oil port of the differential pressure matching type bidirectional flow control valve through the two-position two-way electromagnetic valve;
an upper piston is arranged in an upper cavity of the bidirectional flow control valve, the upper piston divides the upper cavity into an upper oil cavity positioned above and a lower oil cavity positioned below, an annular groove is formed in the inner wall of the middle of the upper cavity and serves as an upper undercut groove, the upper oil cavity and the upper undercut groove are kept communicated through an upper valve body inner oil channel arranged in the valve body, and an upper spring is connected between the upper piston and the inner top surface of the upper cavity; a lower piston is arranged in a lower cavity of the bidirectional flow control valve, the lower piston divides the lower cavity into a lower upper oil cavity positioned above and a lower oil cavity positioned below, an annular groove is formed in the inner wall of the middle of the lower cavity and serves as a lower cutting groove, the lower upper oil cavity and the lower cutting groove are kept communicated through a lower valve body inner oil passage arranged in the valve body, and a lower spring is connected between the lower piston and the inner bottom surface of the lower cavity; the elasticity of the upper spring is greater than that of the lower spring; an intermediate cone valve is fixedly connected between the upper piston and the lower piston, and the conical surface of the intermediate cone valve is used for being matched and connected with the step surface between the upper cavity and the lower cavity in the valve body.
The outer edges of the bottom surfaces of the upper piston and the lower piston are both provided with a notch groove as a throttling groove; the throttling groove of the upper piston and the upper sinking groove are always communicated, and the throttling groove of the upper piston and the sinking groove are always communicated.
The axial groove width of the upper undercut groove is smaller than the actual contact thickness between the upper piston and the inner wall of the upper cavity, and the axial groove width of the undercut groove is smaller than the actual contact thickness between the lower piston and the inner wall of the lower cavity.
The top oil port and the middle oil port are used as internal flow ports of the hydraulic large-flow control unit, the hydraulic oil port and the bottom oil port are used as external flow ports of the hydraulic large-flow control unit, the hydraulic oil port is connected with a hydraulic load, and the bottom oil port is connected with an oil tank; the flow between the tank and the hydraulic load is greater than the operating flow of the bidirectional gear pump.
An upper throttling channel is formed between the throttling groove on the bottom surface of the upper piston and the lower edge of the upper sink cutting groove, and a lower throttling channel is formed between the throttling groove on the bottom surface of the lower piston and the lower edge of the lower sink cutting groove; the upper piston, the lower piston and the middle cone valve are coaxially connected to form a valve core, and the valve core moves up and down in the upper cavity and the lower cavity along the axial direction to drive the upper throttling channel and the lower throttling channel to increase and decrease, so that the adjustment and control of the flow rate are realized.
When the middle cone valve is in matched contact sealing with the step surfaces between the upper cavity and the lower cavity, the upper throttling channel and the lower throttling channel keep flowing and have the minimum throttling area; as the middle cone valve rises, the upper throttling channel and the lower throttling channel are continuously increased.
Secondly, a pressure difference matching type bidirectional large-flow hydraulic control method:
A) when high-pressure oil enters the bottom oil port, the hydraulic oil port is connected with the low-pressure oil way, the high-pressure oil enters the lower oil cavity of the lower part, the valve core is pushed to move upwards, the middle cone valve is opened, and the lower oil cavity of the upper part is communicated with the upper oil cavity of the lower part; meanwhile, the controller opens the two-position two-way electromagnetic valve, controls the two-way gear pump to pump hydraulic oil into the upper oil chamber from the lower oil chamber at the upper part at a smaller flow rate, increases the oil pressure in the upper oil chamber at the upper part, and increases the downward pressure difference borne by the upper piston, and because the area of the upper piston is larger than that of the lower piston, the change amount of the pressure difference force of the upper piston is faster, so that the valve core is simultaneously borne by the thrust of upward high-pressure oil and downward pressure brought by the suction of the two-way gear pump 17; the rotating speed, namely the flow rate, of the bidirectional gear pump is adjusted, so that the upward differential pressure force borne by the lower piston and the downward differential pressure force borne by the upper piston are balanced, namely the valve core reaches a balance position, and the balance position is determined by the flow rate required by a system;
at the moment, the flow from the bottom oil port to the hydraulic oil port is positively controlled by the miniature bidirectional gear pump, namely the flow discharged by the bidirectional gear pump is increased, the downward differential pressure force exerted on the upper piston is increased, the upward differential pressure force exerted on the lower piston is unchanged, the valve core can descend and reach the position where the differential pressure force is balanced again, the throttling area of the upper throttling channel is reduced, the throttling area of the lower throttling channel is synchronously reduced, and therefore the flow of the system overflowing is also reduced;
or realizing reverse control according to the reverse direction of the forward control;
B) when the hydraulic oil port feeds high-pressure oil, the bottom oil port is connected with a low-pressure oil way; when the two-position two-way electromagnetic valve is opened by the controller and the bidirectional gear pump is controlled to pump hydraulic oil into the upper oil cavity from the upper part at a lower flow rate; in the process, the oil pressure in the upper oil cavity of the upper part is reduced by the suction of the bidirectional gear pump, the pressure in the lower oil cavity of the upper part is unchanged, so that the upper piston is subjected to upward differential pressure, and the upward differential pressure applied to the upper piston is increased quickly because the area of the upper piston is larger than that of the lower piston;
when the rotation speed of the bidirectional gear pump is fast enough and the flow rate is large enough, the pressure difference force borne by the upper piston is larger than that borne by the middle cone valve, the valve core is pushed to move upwards, the middle cone valve is opened, and the communication between the upper oil cavity and the lower oil cavity is opened; the rotating speed, namely the flow rate, of the bidirectional gear pump is adjusted, so that the differential pressure force exerted on the upper piston and the lower piston of the valve core is balanced, and finally the valve core reaches a balance position; at the moment, oil flows through the lower upper oil cavity, the oil duct and the undercut groove from the hydraulic oil port, and then flows into the bottom oil port through the lower throttling channel and the lower oil cavity;
at this moment, the flow from the hydraulic oil port to the bottom oil port is positively controlled by a miniature bidirectional gear pump: the flow discharged by the bidirectional gear pump is increased, the upward differential pressure force borne by the upper piston is increased, the valve core is lifted, the throttling area of the upper throttling channel is increased, the throttling area of the lower throttling channel is synchronously increased, and therefore the flow of the system overflowing is also increased;
or the reverse control is implemented in the reverse direction of the above-described forward control.
Said B) is replaced by the following C):
C) a second two-position two-way electromagnetic valve is added in the oil circuit of the system, one oil port of the second two-position two-way electromagnetic valve is connected between the bidirectional gear pump and the oil circuit of the two-position two-way electromagnetic valve, and the other oil port is connected with the bottom oil port of the bidirectional flow control valve;
when high-pressure oil enters from the hydraulic oil port, the bottom oil port is connected with the low-pressure oil way, when the hydraulic oil port starts, the upper and lower pressures applied to the upper piston are equal due to the communication between the upper throttling channel on the upper piston and the oil way in the upper valve body, the middle cone valve is pressed on the step of the valve body under the pressure of the high-pressure oil at the hydraulic oil port, the controller closes the two-position two-way electromagnetic valve, opens the second two-position two-way electromagnetic valve, and controls the bidirectional gear pump to pump the hydraulic oil out of the upper oil cavity at the upper part at a smaller flow rate and into the lower oil cavity at the lower part at the same time; in the process, the oil pressure in the upper oil cavity of the upper part is reduced by the suction of the bidirectional gear pump, the pressure in the lower oil cavity of the upper part is unchanged, so that the upward differential pressure force applied to the upper piston is increased quickly because the area of the upper piston is larger than that of the lower piston;
when the rotation speed of the bidirectional gear pump is fast enough and the flow rate is large enough, the pressure difference force borne by the upper piston is larger than that borne by the middle cone valve, the valve core is pushed to move upwards, the middle cone valve is opened, and the communication between the upper oil cavity and the lower oil cavity is opened; the rotation speed, namely the flow rate, of the bidirectional gear pump is adjusted, and finally the differential pressure force exerted on the upper piston and the lower piston of the valve core is balanced, so that the valve core reaches a balance position; oil flows from the hydraulic oil port through the lower upper oil cavity, the oil duct and the undercut groove, and then flows into the bottom oil port through the lower throttling channel and the lower oil cavity.
At this moment, the flow from the hydraulic oil port to the bottom oil port is positively controlled by a miniature bidirectional gear pump: the flow discharged by the bidirectional gear pump is increased, the upward differential pressure force borne by the upper piston is increased, the valve core is lifted, the throttling area of the upper throttling channel is increased, and the throttling area of the lower throttling channel is synchronously increased, so that the flow of the system overflowing from the oil port to the oil port is also increased;
or the reverse control is implemented in the reverse direction of the above-described forward control.
Therefore, the purpose of accurately controlling the large flow from the hydraulic oil port to the bottom oil port by accurately controlling the micro flow discharged by the micro gear pump is achieved.
The oil inlet and outlet of the bidirectional miniature gear pump are respectively connected with different oil cavities of the control unit, the oil inlet and outlet of the miniature gear pump are controlled by a two-position two-way electromagnetic valve, and controllable micro flow generated by the bidirectional gear pump flows through a throttling channel and controllable pressure difference is generated at two ends of the throttling channel; the miniature servo motor is connected with the bidirectional gear pump.
When no control signal is input, the flow control device is equivalent to a simple hydraulic one-way valve and is used for stopping the flow of hydraulic oil from the middle oil port to the bottom oil port. When the proportional control valve is used for accurately controlling the large flow, the proportional control valve can completely replace the traditional proportional control valve to realize the accurate control of the flow, so that the movement speed of the controlled oil cylinder is accurately controlled.
The control device is opened only when pressure oil needs to be supplied, and therefore, the energy utilization efficiency is high. Meanwhile, the control mode is digital control, the flow of the miniature quantitative pump is controlled by the miniature servo motor, the flow of the main oil way is controlled by a large amplification factor, and the control is convenient and reliable.
The pressure difference matching type bidirectional flow control valve is characterized in that: the opening degree of a throttling channel on a piston in a valve core is always synchronous through the size of machining, and the throttling area is in a certain proportion, so that the flow of hydraulic oil entering and exiting the oil cylinder and the flow discharged by the miniature gear pump are in a fixed proportional relation, and the valve is completely controllable. Namely: the flow of the hydraulic oil in and out of the whole flow control device is controlled by controlling the miniature bidirectional gear pump to suck out or pump the hydraulic oil into different oil cavities in the differential pressure matching type bidirectional flow control valve, and the flow control device is hardly influenced by the outside.
Therefore, compared with the prior art, the invention has the beneficial effects that:
1. the flow control system based on the differential pressure matching type bidirectional flow control valve has low cost, is stable and reliable, can abandon the original servo or proportional valve for controlling the flow, and greatly reduces the cost of the hydraulic control system;
2. the flow control system based on the pressure difference matching type bidirectional flow control valve reduces the requirements of a flow feedback link, thereby not only reducing the processing difficulty, but also reducing the requirements on the cleanliness of hydraulic oil and the influence on the oil temperature;
3. compared with the traditional hydraulic servo system based on a proportional valve or a servo valve, the flow control system of the differential pressure matching type bidirectional flow control valve provided by the invention can effectively control the flow in the hydraulic system, the control method is greatly simplified, and the flow of hydraulic oil entering and exiting the oil cylinder can be accurately controlled only by controlling the rotating speed of a servo motor in the system.
4. The flow control system based on the pressure difference matching type bidirectional flow control valve belongs to a volume type control system (pump control system), and compared with a proportional valve or a servo valve, the flow control system can effectively improve the energy efficiency of a hydraulic control system and reduce the heat productivity of the system.
In summary, the digitally controlled hydraulic flow control unit of the present invention can ensure low cost, reliability, convenient and stable control, environment-friendly use, insensitivity to oil temperature and cleanliness, and can effectively ensure the position and speed requirements of the operation of the execution unit in the high flow hydraulic system, even when used for the accurate control of the high flow.
Drawings
FIG. 1 is a schematic structural diagram of a first operating state of a pressure differential matching type bidirectional flow control device according to the present invention;
FIG. 2 is a schematic structural diagram of a pressure-difference-matching bidirectional flow control device of the present invention in a second operating state;
FIG. 3 is a schematic structural diagram of a pressure differential matching type bidirectional flow control device of the present invention in a third operating state;
FIG. 4 is a schematic structural view of the pressure-difference-matching bidirectional flow control device of the present invention in a fourth operating state;
fig. 5 is a schematic structural view of the pressure-difference-matching bidirectional flow control device in a fifth working state.
In the figure: the hydraulic oil-gas mixing device comprises an upper spring 1, an upper oil cavity 2, an upper undercut groove 3, an upper piston 4, an upper throttling channel 5, a hydraulic oil port 6, an upper lower oil cavity 7, a middle cone valve 8, a lower oil cavity 9, an undercut groove 10, a lower piston 11, a lower throttling channel 12, a bottom oil port 13, a lower spring 14, a two-position two-way electromagnetic valve 16, a miniature two-way gear pump 17, a servo motor 18, a controller 19, a differential pressure matching type two-way flow control valve 20, a top oil port 21, a middle oil port 22, an upper valve body oil duct 23, a lower valve body oil duct 24, a lower oil cavity 25 and a second two-position two-way electromagnetic valve 15.
Detailed Description
The above and further features and advantages of the present invention will become apparent from the following more particular description of the invention, as illustrated in the accompanying drawings.
As shown in fig. 1, a schematic diagram of a two-way flow control valve and a flow control device based on differential pressure matching according to an embodiment of the present invention is mainly composed of a digital control type servo motor 18, a micro two-way gear pump 17, a controller 19, a two-position two-way solenoid valve 16, and a two-way flow control valve 20 based on differential pressure matching;
the pressure difference matching type bidirectional flow control valve 20 comprises a valve body, an upper cavity and a lower cavity which are respectively arranged in the valve body up and down, the valve body is hollow, the upper cavity and the lower cavity are directly and coaxially communicated, and the inner diameter of the upper cavity at the upper part is larger than that of the upper cavity at the lower part, so that a step is formed between the upper cavity and the lower cavity; a top oil port 21 is formed in the top end of the valve body at the top of the upper cavity, a bottom oil port 13 is formed in the bottom end of the valve body at the bottom of the lower cavity, a middle oil port 22 and a hydraulic oil port 6 are formed in the side wall of the valve body between the upper cavity and the lower cavity, and the middle oil port 22 and the hydraulic oil port 6 can be symmetrically arranged on two sides;
the control shaft of the bidirectional gear pump 17 is connected with a servo motor 18, the servo motor 18 is electrically connected with a controller 19, the servo motor 18 is a low-power motor and is connected with the miniature bidirectional gear pump 17, and the controller 19 sends an instruction to control the rotating speed of the servo motor 18 so as to control the flow of the miniature bidirectional gear pump 17. One oil port of the bidirectional gear pump 17 is connected with a top oil port 21 of a differential pressure matching type bidirectional flow control valve 20, and the other oil port of the bidirectional gear pump 17 is connected with a middle oil port 22 through a two-position two-way electromagnetic valve 16;
the miniature bidirectional gear pump is driven by a digital control type servo motor or a direct current speed regulating motor; the two-position two-way electromagnetic valve is used for connecting an oil port of the control micro gear pump to different oil cavities of the differential pressure matching type bidirectional flow control valve; the servo motor is connected with the bidirectional gear pump.
An upper piston 4 is arranged in an upper cavity of the bidirectional flow control valve 20, the upper cavity is divided into an upper oil cavity 2 at the upper part above the upper piston 4 and an upper oil cavity 7 at the lower part of the upper piston 4 by the upper piston 4, an annular groove is formed in the inner wall of the middle part of the upper cavity to serve as an upper undercut groove 3, the upper oil cavity 2 and the upper undercut groove 3 are always kept communicated through an upper valve body oil channel 23 arranged in the valve body, an upper spring 1 is connected between the upper piston 4 and the inner top surface of the upper cavity, and the inner top surface of the upper cavity is the inner top surface of the upper oil cavity 2; a lower piston 11 is arranged in a lower cavity of the bidirectional flow control valve 20, the lower piston 11 divides the lower cavity into a lower upper oil cavity 9 positioned above the lower piston 11 and a lower oil cavity 25 positioned below the lower piston 11, an annular groove is formed in the inner wall of the middle part of the lower cavity to serve as a lower sink cutting groove 10, the lower upper oil cavity 9 and the lower sink cutting groove 10 are always kept communicated through a lower valve body inner oil channel 24 arranged in the valve body, a lower spring 14 is connected between the lower piston 11 and the inner bottom surface of the lower cavity, and the inner top surface of the lower cavity is the inner top surface of the lower oil cavity 25; an intermediate cone valve 8 is fixedly connected between the upper piston 4 and the lower piston 11, the upper piston 4 is coaxially and fixedly connected with the lower piston 11 and the intermediate cone valve 8, and the peripheral bottom surface of the intermediate cone valve 8 is used for being matched and connected with a step surface between the upper cavity and the lower cavity to form sealing; the upper piston 4, the lower piston 11 and the middle cone valve 8 are coaxially connected to form a valve core of an oil cavity.
The outer edges of the bottom surfaces of the upper piston 4 and the lower piston 11 are both provided with a notch groove as a throttling groove, the size is ensured by machining, so that the upper throttling groove and the lower throttling groove are always synchronously opened and are used as variable throttling channels, and the throttling areas are always kept in the same proportion in the moving process of the valve core; the throttling groove of the upper piston 4 and the upper undercut groove 3 are always communicated, and the throttling groove of the lower piston 11 and the lower undercut groove 10 are always communicated.
The axial groove width of the upper undercut groove 3 is smaller than the actual contact thickness between the upper piston 4 and the inner wall of the upper cavity, and the axial groove width of the lower undercut groove 10 is smaller than the actual contact thickness between the lower piston 11 and the inner wall of the lower cavity.
The top oil port 21 and the middle oil port 22 are used as internal flow ports of the hydraulic large-flow control unit, the hydraulic oil port 6 and the bottom oil port 13 are used as external flow ports of the hydraulic large-flow control unit, the hydraulic oil port 6 is connected with a hydraulic load, the hydraulic load is usually one of the cavities of a hydraulic cylinder, and the bottom oil port 13 is connected with an oil tank; the flow between the tank and the hydraulic load is much greater than the working flow of the bidirectional gear pump 17.
A hydraulic oil port 6 of the differential pressure matching type bidirectional flow control valve is an oil outlet and is connected with a controlled hydraulic cylinder or other oil paths; the bottom oil port 13 of the bidirectional flow control valve 20 is an oil inlet and is connected with an oil supply circuit or an oil tank; but also can be exchanged, the hydraulic oil port 6 is an oil inlet, and the bottom oil port 13 is an oil outlet.
The middle oil port and the bottom oil port of the differential pressure matching type flow control valve can be used as oil inlets or oil outlets of the flow control valve, and bidirectional flow control is achieved.
An upper throttling channel 5 is formed between the throttling groove on the bottom surface of the upper piston 4 and the lower edge of the upper undercut groove 3, and a lower throttling channel 12 is formed between the throttling groove on the bottom surface of the lower piston 11 and the lower edge of the lower undercut groove 10; the upper piston 4, the lower piston 11 and the middle cone valve 8 are coaxially connected to form a valve core, and the valve core moves up and down in the upper cavity and the lower cavity along the axial direction to drive the upper throttling channel 5 and the lower throttling channel 12 to increase and decrease, so that the flow regulation and control are realized. The upper throttling channel 5 and the lower throttling channel 12 change in the same direction, i.e. the upper throttling channel 5 increases, the lower throttling channel 12 also increases and vice versa. Thus, synchronous opening of the throttle is ensured, the throttle area synchronously changes along with the displacement of the valve core, but the ratio of the throttle areas on the upper piston and the lower piston is kept unchanged.
In specific implementation, the two-position two-way electromagnetic valve 16 is electrically connected to the controller 19, and the controller 19 drives the two-position two-way electromagnetic valve 16 to be switched on and off.
The oil inlet and outlet of the bidirectional miniature gear pump are respectively connected with different oil cavities of the flow control unit, the on-off of the oil inlet and outlet of the miniature gear pump is controlled by a two-position two-way electromagnetic valve, and the controllable micro flow generated by the bidirectional gear pump flows through a V-shaped throttling channel on a valve core piston and generates controllable pressure difference at two ends of the valve core piston.
The positions of a middle conical valve core of the valve core in the differential pressure matching type flow control valve, a V-shaped groove on the piston, a sink-cut groove on the valve body and a step must be strictly matched, and a throttling channel on the piston only has a small throttling area for transmitting hydraulic oil pressure before the valve core of the conical valve is lifted. Specifically, when the middle cone valve 8 is in fit contact with and sealed with the step surfaces between the upper cavity and the lower cavity, the upper throttling channel 5 and the lower throttling channel 12 are kept in circulation, and the throttling area is the smallest; as the intermediate cone valve 8 rises, the upper throttle passage 5 and the lower throttle passage 12 increase continuously.
The specific throttling groove is a V-shaped throttling groove, or can be arranged in a semi-arc shape or a rhombic shape and other shapes.
The flow rate of the liquid flowing through the flow control unit is determined by the pressure difference of a V-shaped throttling channel on the lower piston in the valve core in the flow control valve and the opening degree of the V-shaped throttling channel. The throttling pressure difference and the position opening degree on the lower piston of the valve core of the pressure difference matching type flow control valve are determined by digital signals for controlling the rotating speed and the direction of the servo motor and the flow of the miniature bidirectional gear pump.
The miniature bidirectional gear pump can also be set as a unidirectional gear pump combined with an electromagnetic directional valve to realize bidirectional flow output.
The bidirectional gear pump 17 is a miniature small flow rate metering pump for providing a precisely controllable control flow rate.
The servo motor 18 is a low-power motor, the low power means that the power of the motor is only used for pushing the valve core to move, the motor is connected with the bidirectional gear pump 17, and the controller 19 sends an instruction to control the rotating speed.
The invention controls the structure of large flow by the structure of small flow, the small flow means that the flow for controlling the movement and the position of the valve core is very small, the large flow means that the whole flow of the outflow and inflow flow control valve is very large, and the digital accurate control under the hydraulic large flow is realized.
The pressure difference of the piston is the difference of the pressures received between the upper end surface and the lower end surface. The differential pressure force is the difference of the thrust force caused by the difference of the pressure above and below the piston, i.e. the pressure difference is multiplied by the corresponding area of the piston
Referring to fig. 1, the first operating state:
when the system is in a standby state, no control instruction is sent from the controller 19, the servo motor 18 and the bidirectional gear pump 17 are in the standby state, the two-position two-way electromagnetic valve 16 is not communicated, at the moment, no pressure oil is supplied to the bottom oil port 13 of the bidirectional flow control valve 20, the pressure is zero, the hydraulic oil port 6 of the bidirectional flow control valve 20 is connected with a load, which can be a certain cavity of an oil cylinder, so that the pressure generated by the load exists; in an initial state, the throttling channels on the upper piston 4 and the lower piston 11 of the valve core have micro throttling areas which are communicated with each other and used for transmitting the pressure of hydraulic oil; the oil pressure in the upper chamber 2 above the upper piston 4 is therefore equal to the oil pressure in the upper lower chamber 7 below the upper piston 4 and to the pressure generated by the load, the upper piston 4 being unstressed; meanwhile, the pressure of the lower upper oil chamber 9 above the lower piston 11 is equal to that of the lower oil chamber 25 below the lower piston, and the pressure is zero; therefore, the middle cone valve 8 is acted by the pressure difference between the upper lower oil chamber 7 and the lower upper oil chamber 9 to form downward pressure, and tightly presses on the step surface in the valve body to form reliable sealing, so that the flow of hydraulic oil from the hydraulic oil port 6 to the bottom oil port 13 is cut off, and the hydraulic cylinder is locked in a one-way mode.
Or when the pressure oil is supplied to the bottom oil port 13 and the hydraulic oil port 6, the pressure is zero; at this time, because the spring force of the upper spring 1 is greater than that of the lower spring 14, the intermediate cone valve 8 is also pressed on the step surface in the valve body by the spring force, and reliable sealing is formed.
The two-way flow control valve 20 now operates like a hydraulic check valve.
Referring to fig. 2, the second operating state:
when the bottom port 13 of the two-way flow control valve 20 has high-pressure hydraulic oil and the hydraulic port 6 has low-pressure hydraulic oil, but it is necessary to stop the flow of the pressure oil from the bottom port 13 to the hydraulic port 6:
at the moment, a control instruction is sent out from a controller 19 to enable a two-position two-way electromagnetic valve 16 to be communicated, a servo motor 18 drives a two-way gear pump 17 to pump oil in an upper lower oil cavity 7 of a two-way flow control valve 20 into an upper oil cavity 2 at the upper part according to a specified rotating speed, and then the oil returns to the lower oil cavity 7 at the upper part through an upper oil passage 23 in the upper valve body, an upper undercut groove 3 and an upper throttling passage 5 below an upper piston 4 in sequence, in the process, the oil pressure in the upper oil cavity 2 at the upper part is increased, the pressure of the lower oil cavity 7 at the upper part is not changed to be equal to the pressure of an oil port 6, and the downward differential pressure force borne by the upper piston 4 is increased; because the throttling channel on the lower piston 11 has a small throttling area for communicating hydraulic oil pressure, the oil pressure in the lower upper oil cavity 9 is larger and equal to the pressure at the bottom oil port 13, the upper-lower pressure difference of the lower piston 11 is zero, and the upper piston 11 is not stressed; while the intermediate cone valve 8 is subjected to an upward differential pressure; however, because the acting area of the upper piston 4 is larger and the acting area of the intermediate cone valve 8 is smaller, the downward pressure applied to the upper piston is larger under the same pressure difference. At this time, by adjusting the rotation speed, i.e. the flow rate, of the bidirectional gear pump 17, the hydraulic oil is continuously pumped into the upper oil chamber 2, when the downward differential pressure force applied to the upper piston 4 is large enough to exceed the upward differential pressure force applied to the intermediate cone valve 8, the differential pressure force applied to the valve core is made downward comprehensively, i.e. the intermediate cone valve 8 and the step surface are tightly pressed and sealed, and the oil flow between the upper oil chamber 7 and the lower oil chamber 9 is blocked.
Thus, the pressure applied to the piston 4 generated by the small flow discharged from the bidirectional gear pump 17 after flowing through the throttle channel is large enough to overcome the force applied to the middle cone valve 8 by the pressure of the bottom oil port 13 of the bidirectional flow control valve 20, and the cone valve portion in the middle of the valve core of the flow control valve 20 is always closed, i.e. the state shown in fig. 2, so as to stop the flow of the hydraulic oil from the oil port 13 to the oil port 6.
Referring to fig. 3, the operating state three:
when the bottom oil port 13 of the bidirectional flow control valve 20 has high-pressure oil, the hydraulic oil port 6 is connected with a low-pressure oil way, and the flow from the bottom oil port 13 to the hydraulic oil port 6 needs to be accurately controlled;
at the beginning, the throttling channels on the upper piston 4 and the lower piston 11 of the valve core have small throttling areas which are communicated for transmitting hydraulic oil pressure, and the oil pressure in the upper oil cavity 2 at the upper part of the upper piston 4 is equal to the oil pressure in the lower oil cavity 7 at the upper part and is equal to the oil pressure of a low-pressure oil circuit; the oil pressure in the lower upper oil chamber 9 of the lower piston 11 is equal to the oil pressure in the lower oil chamber 25, and is equal to the high-pressure oil line pressure; therefore, the upper surface and the lower surface of the middle cone valve 8 form a pressure difference, and the pressure difference force is upward, so that the valve core is driven to move upward, and the middle cone valve 8 is separated from the step surface; the upper oil chamber 7 and the lower oil chamber 9 are communicated;
meanwhile, the controller 19 controls the two-position two-way electromagnetic valve 16 to be communicated, controls the rotating speed of the two-way gear pump 17 by adopting closed-loop control, and simultaneously acquires flow information required by the oil outlet 6 or running speed information of a corresponding oil cylinder; the oil in the upper lower oil chamber 7 is pumped into the upper oil chamber 2 through a bidirectional gear pump 17 and then returns to the upper lower oil chamber 7 through an upper valve body oil passage 23, an upper undercut groove 3 and an upper throttling channel 5 below an upper piston 4 in sequence; by controlling the rotating speed of the bidirectional gear pump 17, the oil pressure in the upper oil cavity 2 is increased by continuous pumping, and the pressure of the lower oil cavity 7 is unchanged because the lower oil cavity is communicated with the hydraulic oil port 6, so that the pressure difference of the upper piston 4 under pressing is increased; since the area of the upper piston 4 is larger than that of the lower piston 11, the same pressure difference changes, and the change amount of the pressure difference force of the upper piston is larger; therefore, the flow discharged by the bidirectional gear pump 17 is controlled to generate a pressure difference force acting on the upper piston 4 after flowing through the throttling channel, so that the upward pressure difference force acting on the lower piston 11 can be just balanced, namely the two forces are kept equal, namely the pressures acting on the upper piston and the lower piston are just balanced, the middle cone valve 8 is separated from the step surface, the upper lower oil chamber 7 and the lower upper oil chamber 9 are communicated and stay at a certain balanced position, and the balanced position is determined by the flow required by the system, namely the running speed required by the oil cylinder; the flow from the bottom port 13 to the hydraulic port 6 is also balanced.
At this time, the flow rate from the bottom port 13 to the hydraulic port 6 is controlled by the micro bidirectional gear pump 17: that is, the flow discharged by the bidirectional gear pump 17 is increased, the downward differential pressure force borne by the upper piston 4 is increased, and the upward differential pressure force borne by the lower piston 11 is unchanged, so that the valve core is lowered, the throttling area of the upper throttling channel 5 is reduced, the throttling area of the lower throttling channel 12 is synchronously reduced, and the flow of the whole system device is also reduced; and vice versa.
The throttle areas of the two throttle channels can have a large proportional relation, so that the large flow from the oil port 13 to the oil port 6 can be accurately controlled by controlling the discharge flow of the miniature gear pump; the pressure difference between two ends of the upper piston 4 is controlled by the miniature bidirectional gear pump 17 to accurately control the position of the valve core, and the opening of the throttling channel of the valve core is controlled, so that the large flow flowing through the whole system is controlled.
Referring to fig. 4, the operating state is four: based on the same differential pressure matching manner.
When the pressure of the hydraulic port 6 of the bidirectional flow control valve 20 is greater than the pressure of the bottom port 13 and the flow from the hydraulic port 6 to the bottom port 13 needs to be accurately controlled;
at the beginning, the throttling channels on the upper piston 4 and the lower piston 11 of the valve core have small throttling areas which are communicated for transmitting hydraulic oil pressure, and the oil pressure in the upper oil cavity 2 at the upper part of the upper piston 4 is equal to the oil pressure in the lower oil cavity 7 at the upper part and is equal to the oil pressure of a high-pressure oil path; the oil pressure in the lower upper oil chamber 9 of the lower piston 11 is equal to the oil pressure in the lower oil chamber 25, and is equal to the low-pressure oil line pressure; therefore, the upper surface and the lower surface of the middle cone valve 8 form a pressure difference, and the pressure difference is downward, so that the middle cone valve 8 compresses the step surface of the valve body;
meanwhile, the controller 19 still adopts a closed-loop control mode to control the two-position two-way electromagnetic valve 16 to be opened for communication, and simultaneously acquires flow information required by the oil port 6 or running speed information of a corresponding oil cylinder; the flow discharged by the miniature gear pump 17 is controlled by a servo motor 18, and oil in the upper oil cavity 2 is sucked and pumped into the upper oil cavity 7; during this process, the oil pressure in the upper oil chamber 2 is lowered; because the oil pressure of the oil port 6 is high under the load pressure, that is, the pressure of the upper lower oil chamber 7 is high and constant, the upper piston 4 is subjected to an upward differential pressure in the process of reducing the oil pressure of the upper oil chamber 2, and when the differential pressure is large enough, the valve core is pushed to move upwards, the intermediate cone valve 8 is separated from the step surface, and the communication between the upper lower oil chamber 7 and the lower upper oil chamber 9 is opened.
After the middle cone valve 8 is separated from the step surface, oil in the upper lower oil chamber 7 enters the lower upper oil chamber 9, so that the oil pressure in the lower upper oil chamber 9 is greater than the oil pressure in the lower oil chamber 25, and the lower piston 11 can bear a downward differential pressure; the upper piston 4 is always subjected to an upward differential pressure because the oil pressure in the upper lower chamber 7 is relatively high due to the pumping action of the gear pump 17 on the upper chamber 2. Finally, through the flow of controlling miniature gear pump 17 exhaust for the downward differential pressure that lower piston 11 received and the upward differential pressure that upper piston 4 received are balanced, and according to the functioning speed of system's hydro-cylinder demand, the case can finally stay in certain balanced position, and hydraulic pressure hydraulic fluid port 6 also can reach the balance to the flow of bottom hydraulic fluid port 13.
At this time, the flow rate from the hydraulic port 6 to the bottom port 13 is controlled by the micro bidirectional gear pump 17: namely, the flow discharged by the bidirectional gear pump 17 is increased, the upward pressure difference borne by the upper piston 4 is increased, the downward pressure difference borne by the lower piston 11 is unchanged, the valve core is pushed to rise, the throttling area of the upper throttling channel 5 is increased, the throttling area of the lower throttling channel 12 is synchronously increased, and the flow of the whole system device is also increased; and vice versa.
Therefore, by accurately controlling the minute flow rate discharged from the micro gear pump 17, the large flow rate from the hydraulic port 6 to the bottom port 13 can be accurately controlled.
Referring to fig. 5, the operation state is five: compared with the state of working state 4, a two-position two-way electromagnetic valve is added
A second two-position two-way electromagnetic valve (15) is added in the oil circuit of the system, one oil port of the second two-position two-way electromagnetic valve (15) is connected between the two-way gear pump (17) and the oil circuit of the two-position two-way electromagnetic valve (16), and the other oil port is connected with a bottom oil port (13) of the two-way flow control valve (20);
when the pressure of the hydraulic port 6 of the bidirectional flow control valve 20 is greater than the pressure of the bottom port 13 and the flow from the hydraulic port 6 to the bottom port 13 needs to be accurately controlled;
at the beginning, the throttling channels on the upper piston 4 and the lower piston 11 of the valve core have small throttling areas which are communicated for transmitting hydraulic oil pressure, and the oil pressure in the upper oil cavity 2 at the upper part of the upper piston 4 is equal to the oil pressure in the lower oil cavity 7 at the upper part and is equal to the oil pressure of a high-pressure oil path; the oil pressure in the lower upper oil chamber 9 of the lower piston 11 is equal to the oil pressure in the lower oil chamber 25, and is equal to the low-pressure oil line pressure; therefore, the upper surface and the lower surface of the middle cone valve 8 form a pressure difference, and the pressure difference is downward, so that the middle cone valve 8 compresses the step surface of the valve body;
meanwhile, the controller 19 still adopts a closed-loop control mode to control the two-position two-way electromagnetic valve 16 to be stopped, open the second two-position two-way electromagnetic valve 15 to be communicated, and simultaneously acquire flow information required by the oil port 6 or running speed information of the corresponding oil cylinder; the flow discharged by the miniature gear pump 17 is controlled by the servo motor 18, and the oil in the upper oil cavity 2 is pumped into the lower oil cavity 25; during this process, the oil pressure in the upper oil chamber 2 is lowered; because the oil pressure of the oil port 6 is high under the load pressure, that is, the pressure of the upper lower oil chamber 7 is high and constant, the upper piston 4 is subjected to an upward differential pressure in the process of reducing the oil pressure of the upper oil chamber 2, and when the differential pressure is large enough, the valve core is pushed to move upwards, the intermediate cone valve 8 is separated from the step surface, and the communication between the upper lower oil chamber 7 and the lower upper oil chamber 9 is opened.
After the middle cone valve 8 is separated from the step surface, oil in the upper lower oil chamber 7 enters the lower upper oil chamber 9, so that the oil pressure in the lower upper oil chamber 9 is greater than the oil pressure in the lower oil chamber 25, and the lower piston 11 can bear a downward differential pressure; the upper piston 4 is always subjected to an upward differential pressure because the oil pressure in the upper lower chamber 7 is relatively high due to the pumping action of the gear pump 17 on the upper chamber 2. Finally, through the flow of controlling miniature gear pump 17 exhaust for the downward differential pressure that lower piston 11 received and the upward differential pressure that upper piston 4 received are balanced, and according to the functioning speed of system's hydro-cylinder demand, the case can finally stay in certain balanced position, and hydraulic pressure hydraulic fluid port 6 also can reach the balance to the flow of bottom hydraulic fluid port 13.
At this time, the flow rate from the hydraulic port 6 to the bottom port 13 is controlled by the micro bidirectional gear pump 17: namely, the flow discharged by the bidirectional gear pump 17 is increased, the upward pressure difference borne by the upper piston 4 is increased, the downward pressure difference borne by the lower piston 11 is unchanged, the valve core is pushed to rise, the throttling area of the upper throttling channel 5 is increased, the throttling area of the lower throttling channel 12 is synchronously increased, and the flow of the whole system device is also increased; and vice versa.
Therefore, by accurately controlling the minute flow rate discharged from the micro gear pump 17, the large flow rate from the hydraulic port 6 to the bottom port 13 can be accurately controlled.
The above-mentioned embodiments are provided to further explain the objects, technical solutions and advantages of the present invention in detail, and it should be understood that the above-mentioned embodiments are only examples of the present invention and are not intended to limit the scope of the present invention. It should be understood that any modifications, equivalents, improvements and the like, which come within the spirit and principle of the invention, may occur to those skilled in the art and are intended to be included within the scope of the invention.
Claims (7)
1. A pressure difference matching type bidirectional large-flow hydraulic control unit is characterized in that,
mainly comprises a servo motor (18), a miniature bidirectional gear pump (17), a controller (19), a two-position two-way electromagnetic valve (16) and a differential pressure matching type bidirectional flow control valve (20); the pressure difference matching type bidirectional flow control valve (20) comprises a valve body, an upper cavity and a lower cavity which are respectively arranged at the upper part and the lower part in the valve body, the upper cavity and the lower cavity are directly and coaxially communicated, and the inner diameter of the upper cavity at the upper part is larger than that of the lower cavity at the lower part, so that a step is formed between the upper cavity and the lower cavity; a top oil port (21) is formed in the top end of the valve body at the top of the upper cavity, a bottom oil port (13) is formed in the bottom end of the valve body at the bottom of the lower cavity, and a middle oil port (22) and a hydraulic oil port (6) are formed in the side wall of the valve body between the upper cavity and the lower cavity; a control shaft of the miniature bidirectional gear pump (17) is connected with a servo motor (18), the servo motor (18) is electrically connected with a controller (19), one oil port of the miniature bidirectional gear pump (17) is connected with a top oil port (21) of the differential pressure matching type bidirectional flow control valve (20), and the other oil port of the miniature bidirectional gear pump (17) is connected with a middle oil port (22) of the differential pressure matching type bidirectional flow control valve (20) through a two-position two-way electromagnetic valve (16);
an upper piston (4) is arranged in an upper cavity of the bidirectional flow control valve (20), the upper cavity is divided into an upper oil cavity (2) located above and a lower upper oil cavity (7) located below by the upper piston (4), an annular groove serving as an upper undercut groove (3) is formed in the inner wall of the middle of the upper cavity, the upper oil cavity (2) and the upper undercut groove (3) are kept communicated through an upper valve body inner oil channel (23) arranged inside a valve body, and an upper spring (1) is connected between the upper piston (4) and the inner top surface of the upper cavity; a lower piston (11) is arranged in a lower cavity of the bidirectional flow control valve (20), the lower piston (11) divides the lower cavity into a lower upper oil cavity (9) positioned above and a lower oil cavity (25) positioned below, an annular groove is formed in the inner wall of the middle part of the lower cavity and serves as a lower sinking groove (10), the lower upper oil cavity (9) and the sinking groove (10) are kept communicated through a lower valve body inner oil channel (24) arranged in the valve body, and a lower spring (14) is connected between the lower piston (11) and the inner bottom surface of the lower cavity; the elasticity of the upper spring (1) is larger than that of the lower spring (14); an intermediate cone valve (8) is fixedly connected between the upper piston (4) and the lower piston (11), and the conical surface of the intermediate cone valve (8) is matched and connected with the step surface between the upper cavity and the lower cavity in the valve body.
2. The pressure difference matching type bidirectional large-flow hydraulic control unit according to claim 1, characterized in that: the outer edges of the bottom surfaces of the upper piston (4) and the lower piston (11) are both provided with a gap groove as a throttling groove; the throttling groove of the upper piston (4) is always communicated with the upper sink cutting groove (3), and the throttling groove of the lower piston (11) is always communicated with the sink cutting groove (10).
3. The pressure difference matching type bidirectional large-flow hydraulic control unit according to claim 2, characterized in that: the upper sinking groove (3) is smaller than the thickness of the upper piston (4) actually contacting with the inner wall of the upper cavity along the axial groove width, and the sinking groove (10) is smaller than the thickness of the lower piston (11) actually contacting with the inner wall of the lower cavity along the axial groove width.
4. The pressure difference matching type bidirectional large-flow hydraulic control unit according to claim 1, characterized in that: the hydraulic control system is characterized in that the top oil port (21) and the middle oil port (22) are used as internal flow ports of the hydraulic high-flow control unit, the hydraulic oil port (6) and the bottom oil port (13) are used as external flow ports of the hydraulic high-flow control unit, the hydraulic oil port (6) is connected with a load, and the bottom oil port (13) is connected with an oil tank; the flow rate between the oil tank and the hydraulic load is greater than the working flow rate of the bidirectional gear pump (17).
5. The pressure difference matching type bidirectional large-flow hydraulic control unit according to claim 1, characterized in that: an upper throttling channel (5) is formed between the throttling groove on the bottom surface of the upper piston (4) and the lower edge of the upper sink groove (3), and a lower throttling channel (12) is formed between the throttling groove on the bottom surface of the lower piston (11) and the lower edge of the lower sink groove (10); the upper piston (4), the lower piston (11) and the middle cone valve (8) are coaxially connected to form a valve core, and the valve core moves up and down in the upper cavity and the lower cavity along the axial direction to drive the upper throttling channel (5) and the lower throttling channel (12) to increase and decrease, so that the flow regulation and control are realized.
6. The pressure difference matching type bidirectional large-flow hydraulic control method applied to any one of claims 1 to 5 is characterized in that:
A) when high-pressure oil enters the bottom oil port (13), the hydraulic oil port (6) is connected with a low-pressure oil way, the high-pressure oil enters the lower oil cavity (25) of the lower part, the valve core is pushed to move upwards, the middle cone valve (8) is opened, and the lower oil cavity (7) of the upper part is communicated with the upper oil cavity (9) of the lower part; meanwhile, the controller (19) opens the two-position two-way electromagnetic valve (16), controls the two-way gear pump (17) to pump hydraulic oil into the upper oil cavity (2) from the lower oil cavity (7) of the upper part, increases the oil pressure in the upper oil cavity (2) of the upper part, and increases the downward differential pressure applied to the upper piston (4), so that the valve core is applied with the thrust of upward high-pressure oil and downward pressure brought by the suction of the two-way gear pump (17); the rotating speed of the bidirectional gear pump is adjusted, so that the upward differential pressure force borne by the lower piston (11) and the downward differential pressure force borne by the upper piston (4) are balanced, namely the valve core reaches a balance position, and the balance position is determined by the flow required by the system;
at the moment, the flow from the bottom oil port (13) to the hydraulic oil port (6) is positively controlled by the miniature bidirectional gear pump (17), namely the flow discharged by the bidirectional gear pump (17) is increased, the downward differential pressure force borne by the upper piston (4) is increased, the upward differential pressure force borne by the lower piston (11) is unchanged, the valve core can descend and reach the position where the differential pressure force is balanced again, the throttling area of the upper throttling channel (5) is reduced, the throttling area of the lower throttling channel (12) is synchronously reduced, and therefore the overflowing flow of the system is also reduced;
or realizing reverse control according to the reverse direction of the forward control;
B) when the hydraulic oil port (6) enters high-pressure oil, the bottom oil port (13) is connected with a low-pressure oil way; initially, the pressure difference between the upper lower oil chamber (7) and the lower upper oil chamber (9) enables the middle cone valve (8) to be subjected to downward pressure difference force, and when the controller (19) opens the two-position two-way electromagnetic valve (16) and controls the two-way gear pump (17) to pump hydraulic oil into the upper lower oil chamber (7) from the upper oil chamber (2); during the process, the oil pressure in the upper oil chamber (2) is reduced by the suction of the bidirectional gear pump (17), and the pressure in the lower oil chamber (7) is unchanged, so that the upper piston (4) is subjected to upward differential pressure;
when the rotating speed of the bidirectional gear pump (17) is fast enough and the flow rate is large enough, the pressure difference force borne by the upper piston (4) is larger than that borne by the middle cone valve (8), the valve core is pushed to move upwards, the middle cone valve (8) is opened, and the communication between the upper lower oil cavity (7) and the lower upper oil cavity (9) is opened; the rotating speed of the bidirectional gear pump (17) is adjusted, so that the differential pressure force exerted on the upper piston and the lower piston of the valve core is balanced, and finally the valve core reaches a balance position; at the moment, oil flows through the lower upper oil cavity (9), the oil duct (24) and the undercut groove (10) from the hydraulic oil port (6), and then flows into the bottom oil port (13) through the lower throttling channel (12) and the lower oil cavity (25);
at this time, the flow rate from the hydraulic oil port (6) to the bottom oil port (13) is positively controlled by a micro bidirectional gear pump (17): namely, the flow discharged by the bidirectional gear pump (17) is increased, the upward differential pressure force applied to the upper piston (4) is increased, the valve core is lifted, the throttling area of the upper throttling channel (5) is increased, the throttling area of the lower throttling channel (12) is synchronously increased, and therefore the flow of the overflowing system is also increased;
or the reverse control is implemented in the reverse direction of the above-described forward control.
7. The pressure difference matching type bidirectional large-flow hydraulic control method according to claim 6, characterized in that: said B) is replaced by the following C):
C) a second two-position two-way electromagnetic valve (15) is added in the oil circuit of the system, one oil port of the second two-position two-way electromagnetic valve (15) is connected between the bidirectional gear pump (17) and the oil circuit of the two-position two-way electromagnetic valve (16), and the other oil port is connected with a bottom oil port (13) of a bidirectional flow control valve (20);
when high-pressure oil enters the hydraulic oil port (6), the bottom oil port (13) is connected with a low-pressure oil way, initially, the pressure difference between the upper lower oil cavity (7) and the lower upper oil cavity (9) enables the middle cone valve (8) to be subjected to downward pressure difference force, at the moment, the controller (19) closes the two-position two-way electromagnetic valve (16), opens the second two-position two-way electromagnetic valve (15), and controls the bidirectional gear pump (17) to pump the hydraulic oil away from the upper oil cavity (2) and into the lower oil cavity (25); during the process, the pumping of the bidirectional gear pump (17) reduces the oil pressure in the upper oil chamber (2), but the pressure in the lower oil chamber (7) is not changed, so that the upper piston (4) is subjected to upward differential pressure;
when the rotating speed of the bidirectional gear pump (17) is fast enough/the flow rate is large enough, so that the differential pressure force borne by the upper piston (4) is larger than that borne by the middle cone valve (8), the valve core is pushed to move upwards, the middle cone valve (8) is opened, and the communication between the upper lower oil cavity (7) and the lower upper oil cavity (9) is opened; the rotating speed, namely the flow rate, of the bidirectional gear pump (17) is adjusted, and finally the differential pressure force borne by the upper piston and the lower piston of the valve core is balanced, so that the valve core reaches a balance position; oil flows through the lower upper oil cavity (9), the oil duct (24) and the undercut groove (10) from the hydraulic oil port (6), and then flows into the bottom oil port 13 through the lower throttling channel (12) and the lower oil cavity (25).
At this time, the flow rate from the hydraulic oil port (6) to the bottom oil port (13) is positively controlled by a micro bidirectional gear pump (17): namely, the flow discharged by the bidirectional gear pump (17) is increased, the upward differential pressure force borne by the upper piston (4) is increased, the valve core is lifted, the throttling area of the upper throttling channel (5) is increased, and the throttling area of the lower throttling channel (12) is synchronously increased, so that the overflowing flow from the oil port (6) to the oil port (13) of the system is also increased;
or the reverse control is implemented in the reverse direction of the above-described forward control.
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| CN107120324A (en) * | 2017-04-24 | 2017-09-01 | 登派液压技术（上海）有限公司 | Gear pump control hydraulic control system of bender |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113819273A (en) * | 2021-09-29 | 2021-12-21 | 太原理工大学 | Novel proportional reversing valve |
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| CN113323933B (en) | 2023-07-18 |
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